RU2588235C2 - Modified polylactic acid fibres - Google Patents

Abstract

FIELD: chemistry; technological processes.

SUBSTANCE: invention relates to chemical technology of producing biodegradable fibres and concerns modified polylactic acid fibres. Method of producing polylactic acid fibres involves mixing in a melt polylactic acid with polyepoxide modifier and a polymer reinforcing additive to form a thermoplastic composition, wherein reinforcing additive is dispersed in form of domains of discrete phase in a continuous polylactic acid phase; subsequent extrusion of thermoplastic composition at temperature higher than approximately 230 °C, which contributes to reaction of polyepoxide modifier with polylactic acid; and passing reacted composition through extrusion head to form fibre.

EFFECT: invention enables to obtain fibre with good mechanical properties, appearing during and after spinning from melt.

22 cl, 5 dwg, 10 tbl, 55 ex

Description

FIELD OF TECHNOLOGY

Repeatedly made various attempts to obtain non-woven fabrics from biodegradable polymers. Despite the fact that fibers from biodegradable polymers have already been obtained, some problems arose during their use. For example, polylactic acid (PMA; polylactic acid, abbreviated "PLA") is one of the most widely used biodegradable and environmentally friendly (renewable) polymers used to produce nonwoven webs. Unfortunately, due to the high glass transition temperature and low crystallization rate of polylactic acid, a nonwoven fabric made of PMA usually has a low bond flexibility and high roughness. In turn, thermally bonded non-woven fabric made of PMC often has low elongation rates, unacceptable in some applications, for example, in the manufacture of an absorbent product. In addition, despite the fact that polylactic acid can withstand high degrees of elongation, a high elongation energy is required to achieve the degree of crystallization necessary to overcome thermal shrinkage. To overcome these disadvantages, it was proposed the introduction of plasticizers in order to reduce the glass transition temperature and increase bond strength and softness. One commonly used plasticizer is polyethylene glycol. Unfortunately, polyethylene glycol tends to stand out from polylactic acid as a separate phase during aging, especially under conditions of high humidity and elevated temperatures, which impairs the mechanical properties of the resulting fiber over time. The addition of plasticizers also leads to other problems, such as destruction upon spinning (drawing) of the fiber from the melt and a decrease in the strength of the melt and the ability to stretch.

Thus, there is a need to obtain fibers from polylactic acid, which have good elongation parameters, but at the same time have high strength.

SUMMARY OF THE INVENTION

According to one aspect of the present invention, a method for producing fiber from polylactic acid is provided. The method includes melt mixing polylactic acid with a polyepoxide modifier to form a thermoplastic composition, the melt mixing being carried out at a temperature above the melting point of polylactic acid but below a temperature of approximately 230 ° C. The number average molecular weight of the polyepoxide modifier is from about 7500 to about 250,000 grams per mole, and the amount of the polyepoxide modifier is from about 0.01 wt.% To about 10 wt.% By weight of polylactic acid. Then the thermoplastic composition is extruded at a temperature exceeding approximately 230 ° C, which contributes to the reaction of the polyepoxide modifier with polylactic acid. The reacted composition is passed through an extrusion die to obtain fiber.

According to another aspect of the present invention, there is provided a polylactic acid fiber having an average diameter of from about 5 to about 25 micrometers. The fiber includes a thermoplastic composition obtained by the reaction of polylactic acid with a polyepoxide modifier, the polyepoxide modifier comprising a copolymer that contains an epoxide-modified (meth) acrylic monomer component and an olefin monomer component. The glass transition temperature of the fiber is from about 55 ° C to about 65 ° C, the peak elongation at peak load (maximum elongation) is about 50% or more, and its tensile strength is from about 0.75 to about 6 gram-denier (which is approximately 7.35 · 10 ^-3 to 58.8 · 10 ^-3 N denier).

Other features and aspects of the present invention are described in more detail below.

BRIEF DESCRIPTION OF GRAPHIC MATERIALS

A full and detailed description of the present invention, including the best examples of carrying out the invention, proposed for familiarization to a person skilled in the art, is given below in this statement, accompanied by the accompanying graphic materials, in which:

Figure 1 presents a diagram of a method that can be applied to obtain fibers according to one embodiment of the present invention;

Figure 2 presents a TEM (transmission electron microscope) photograph (60 kV, 10,000-fold increase) of the polymer mixture obtained in Example 4, which contains 90 wt.% PLA (PMA, polylactic acid) 6201 D (Natureworks® ) and 10 wt.% ternary copolymer of ethylene, methyl acrylate and glycidyl methacrylate;

Figure 3 presents a TEM photograph (80 kV, 10,000-fold) of the polymer mixture obtained in Example 49, which contains 98.23 wt.% PLA 6201 D (Natureworks®), 2.52 wt.% PP3155 (Exxonmobil) and 0.75 wt.% Lotader® AX8900 (Arkema);

Figure 4 presents a TEM photograph (80 kV, 10,000-fold) of the polymer mixture obtained in Example 50, which contains 89.5 wt.% PLA 6201 D (Natureworks®), 10 wt.% PP3155 (Exxonmobil ) and 0.5 wt.% CESA ™ Extend 8478 (Clariant Corporation); and

Figure 5 presents a TEM photograph (60 kV, 10,000 times) of the polymer mixture obtained in Example 51, which contains 98.5 wt.% PLA 6201 D (Natureworks®) and 1.5 wt.% Lotader ® AX8900 (Arkema).

Repeatedly used in the present description and graphic materials symbols refer to the same or similar features or elements of the invention.

DETAILED DESCRIPTION OF THE EMBODIMENTS OF THE INVENTION

Various embodiments of the invention are presented below, one or more of which are presented in more detail. Each of the examples is provided to explain the invention and does not limit the scope of the invention. Indeed, it will be apparent to those skilled in the art that various modifications and changes may be made to the present invention without departing from the spirit or letter of the invention. For example, features considered or described as part of one embodiment may be included in another embodiment, which in this case forms yet another embodiment. Thus, such modifications and changes are included within the scope of the claims and their equivalents.

Definitions

As used herein, the term “biodegradable” or “biodegradable polymer” generally means a material that is degraded by naturally occurring microorganisms, such as bacteria, fungi and algae; increased ambient temperature; moisture or other environmental factors. The biodegradability of the material can be determined using ASTM 5338.92 test method.

As used herein, the term “fibers” refers to elongated extrudates obtained by passing a polymer through a molding hole, for example, a die (die). Unless otherwise specified, the term “fibers” includes both discrete fibers having a specific length and substantially continuous filaments. For example, the length of such filaments can significantly exceed their diameter, so that the ratio of length to diameter (“aspect ratio”) exceeds approximately 15,000 to 1, and in some cases exceeds approximately 50,000 to 1.

As used herein, the term “one component” refers to fibers made from a single polymer. Of course, this does not preclude the addition of color-adding additives, antistatic properties, lubricating properties, hydrophilicity, the ability to not be wetted by liquids, etc.

Used in the present description, the term "multicomponent" refers to fibers obtained from at least two polymers (for example, to bicomponent fibers), which are obtained by extrusion in different extruders. The polymers are located in distinct areas having a substantially constant location in the cross section of the fibers. The components can be arranged in accordance with any desired configuration, for example, a shell-core configuration, along each other, such as a segmented pie, island-in-the-sea, etc. . Various methods for the preparation of multicomponent fibers are described in US Pat. US 5336552, Strack. et al. and US 6200669, Marmon, et al., the contents of which are fully incorporated into this description by reference for any purpose. Multicomponent fibers having various irregular shapes can also be obtained, for example, the fibers described in US Pat. Nos. 5,277,976 to Hogle. et al., US 5162074. Hills. US 5466410, Hills, US 5069970, Largman, et al. and US 5057368, Largman. et al., the contents of which are fully incorporated into this description by reference for any purpose.

Used in the present description, the term "non-woven fabric" refers to a fabric, the structure of which consists of randomly laid individual fibers, in contrast to the ordered structure of the woven fabric. Non-woven webs include, for example, meltblown webs, meltblown webs (spunbond), carded webs, webs made from wet-formed fibers, webs made from dry-air formed fibers, conformal webs, webs obtained from hydraulically entangled fibers, etc. The density (bulk) of the non-woven fabric may be different, but usually ranges from about 5 grams per square meter ("g / sq.") To 200 g / sq., In some embodiments, from about 10 g / sq. .m. up to about 150 g / m2, and in some embodiments, from about 15 g / m2. up to approximately 100 g / sq.m.

As used herein, the term "melt-blown" web or layer generally refers to a non-woven web obtained by a method in which molten thermoplastic material is extruded through a plurality of small, usually round holes of a capillary die in the form of molten fibers into converging gas streams having a high the speed (for example, air) at which the thinning of the fibers from the molten thermoplastic material occurs, that is, a decrease in their diameter, which can yt reduced to microfiber diameter (microfiber). Then, the fibers obtained by the aerodynamic method from the melt are transported using a high-speed gas stream and placed on the collection surface to form a web of randomly distributed fibers obtained by aerodynamic molding. Such a method is described, for example, in patents US 3849241, Butin, et al., US 4307143, Meitner, et al. and US 4707398, Wisneski. et al., the contents of which are fully incorporated into this description by reference for any purpose. The meltblown fibers can be substantially continuous or discrete, and when deposited on a collection surface, they are usually tacky.

Used in the present description, the term "obtained by high-speed melt spinning (spunbond)" fabric or layer usually refers to a non-woven fabric containing essentially continuous filaments of small diameters. The filaments are obtained by extruding molten thermoplastic material from a variety of small, usually round, capillaries of a die, the diameter of the extrudable filaments then being rapidly reduced by, for example, eductive drawing and / or other well-known melt spinning processes. Obtaining paintings by high-speed melt molding is described and shown, for example, in patents US 4340563, Appel, et al., US 3692618, Dorschner. et al., US 3802817, Matsuki. et al., US 3338992, Kinnev, US 3341394, Kinnev, US 3502763, Hartman, US 3502538, Levy, US 3542615, Dobo, et al. and US 5382400, Pike, et al., the contents of which are fully incorporated into this description by reference for any purpose. Threads obtained by high-speed melt spinning are usually not sticky when deposited on a collection surface. In some cases, the diameters of the melt-spinning filaments can be less than about 40 micrometers and often from about 5 to about 20 micrometers.

Test methods

Melt Flow Rate:

The melt flow rate (English Melt Flow Rate, abbreviated "MFR") is the mass of polymer (in grams) pressed through the holes of an extrusion rheometer (0.0825 in diameter (which is approximately 2 mm)) under a load of 2160 grams , for 10 minutes, usually at 190 ° C or 230 ° C. Unless otherwise indicated, melt flow rate is measured in accordance with the ASTM D1239 test method using a Tinius Olsen extrusion plastometer.

Thermal properties:

The melting point and glass transition temperature can be determined using differential scanning calorimetry (DSC). The calorimeter for differential scanning calorimetry may be a DSC Q100 differential scanning calorimeter equipped with a liquid nitrogen cooling device and UNIVERSAL ANALYSIS 2000 analytical software (version 4.6.6), supplied by T.A. Instruments Inc., New Castle, Delaware. Use tweezers or other tools to prevent direct operator contact with the samples. Samples are placed in an aluminum cup and weighed to the nearest 0.01 milligrams on an analytical balance. A lid is placed on top of the sample material in the cup. Typically, polymer granules are placed directly in a weighing dish, and the fibers are cut to fit them in a weighing dish and lidding.

The differential scanning calorimeter was calibrated using an indium metal reference, and baseline correction was performed as described in the differential scanning calorimeter instruction manual. A sample of material was placed in a differential scanning calorimeter test chamber using an empty cup as a reference. All tests were carried out while purging the test chamber with nitrogen (industrial quality) at a rate of 55 cubic centimeters per minute. The heating and cooling program used in testing samples of polymer granules included 2 test cycles, which began with balancing the chamber at a temperature of -30 ° C, after which the first heating period was performed at a heating rate of 10 ° C per minute to a temperature of 200 ° C, then the sample was equilibrated at 200 ° C for 3 minutes, and then the first cooling period was performed at a cooling rate of 10 ° C per minute to a temperature of -30 ° C, after which balancing was performed e of the sample at -30 ° C for 3 minutes, and then a second heating period was performed at a heating rate of 10 ° C per minute to a temperature of 200 ° C. The heating and cooling program used in testing fiber samples included 1 test cycle, which began with balancing the chamber at -25 ° C, after which the heating period was carried out at a heating rate of 10 ° C per minute to a temperature of 200 ° C , then the sample was equilibrated at 200 ° C for 3 minutes, and then a cooling period was carried out at a cooling rate of 10 ° C per minute to a temperature of -30 ° C. All tests were carried out while purging the test chamber with nitrogen (industrial quality) at a rate of 55 cubic centimeters per minute.

The results were evaluated using the UNIVERSAL ANALYSIS 2000 analytical software, which was used to find and evaluate kinks on the glass transition temperature (Tg) graph, find the endothermic and exothermic peaks, and determine the areas under the peaks on the DSC plots. The glass transition temperature was determined in the region where a distinct change in the slope of the curve was observed, and the melting temperature was determined using an automated calculation of kinks.

Determination of tensile ability:

Individual fiber samples were shortened (for example, trimmed with scissors) to a length of 38 millimeters and placed separately on black velvet fabric. Thus, 10 to 15 fiber samples were collected. Then, the fiber samples were placed in an almost straight state on a rectangular paper frame, the external dimensions of which were 51 millimeters × 51 millimeters, and the inner dimensions were 25 millimeters × 25 millimeters. The ends of each fiber sample were attached to the frame with a working joint, carefully attaching the ends of the fibers to the sides of the frame with adhesive tape. Then, the external, relatively shorter, cross-sectional size of each fiber sample was measured using a traditional, carefully calibrated laboratory microscope mounted at 40x magnification. This fiber cross-sectional size was recorded as the diameter of a single fiber sample. The frame allows you to fix the ends of the fiber samples in the upper and lower clamps of the tensile testing device with a constant speed of stretching, without damaging the fiber samples.

For testing, a tensile testing device with a constant tensile rate and a suitable load sensor were used. A load sensor (e.g., UN) was selected so that the applied load was 10 to 90% of the range of the load scale. A tensile tester (i.e., MTS SYNERGY 200) and load cell are available from MTS Systems Corporation, Eden Prairie, Michigan. Then, the fiber samples in the frame were placed between the clamps of the tensile testing apparatus, workingly fixing the ends of the fibers in the clamps of the tensile testing apparatus. Then, the sides of the paper frame parallel to the length of the fibers were trimmed or otherwise separated so that the force exerted in the tensile testing apparatus was applied only to the fibers. The fibers were then stretched at a stretching speed and a clamp moving speed of 12 inches (approximately 0.3 m) per minute. The data obtained was analyzed using TESTWORKS 4 software supplied by MTS Corporation, with the following test parameters:

Data entered for calculation Test data Break mark drop fifty% Tear sensitivity 90% Extension of a break marker (Break marker elongation) 0.1 inch (approximately 0.25 cm) Threshold breaking load 10 gram power (approximately 98 N) Nominal gage length 1 inch (approximately 2.54 cm) Data collection frequency 10 Hz Non-preload (Slack pre-load) 1 lbf (Ibf, approximately 4.448 N) Denier 9000 m Slope segment length twenty% Density 1.25 g / cm ³ Yield offset 0.20% starting speed 12 in / min (approximately 30 cm / min) Yield segment length 2% Secondary speed 2 inch / min (approximately 5 cm / min)

The values of tensile strength were expressed in gram-force denier. The maximum elongation (% elongation at break) was also measured.

Moisture contents

Moisture content can be determined using the Arizona Instruments Computrac Vapor Pro Moisture Content Analyzer (Model No. 3100) in accordance with ASTM D 7191-05, the contents of which are incorporated herein by reference for all purposes. The test temperature (§X2.1.2) can be 130 ° C, the sample size (§X2.1.1) can be 2 to 4 grams, and the purge time for the vial (§X2.1.4) can be 30 seconds. Additionally, the criteria for completing the test (§X2.1.3) can be defined as the “pre-assessment compliance” mode, which means that the test is completed when satisfactory compliance is achieved with the criteria established by the program (which mathematically calculates the final moisture content value).

INTELLIGENCE. SUMMARY OF THE INVENTION

In General, the present invention relates to a method for producing fibers from polylactic acid, which comprises mixing polylactic acid with a polyepoxide modifier to form a thermoplastic composition, extruding the thermoplastic composition through an extrusion die and then passing the extruded composition through the extrusion die to form a fiber. Not limited to any theory, it can be assumed that the polyepoxide modifier reacts with polylactic acid, which leads to branching of the main polymer chain, which, in turn, increases the strength and stability of the melt during fiber spinning, but does not lead to a significant decrease in temperature glass transition. The branching caused by the reaction can also lead to an increase in molecular weight, which can improve the plastic deformation ability of the fiber and the ability to dissipate energy when a tensile force is applied. To minimize the likelihood of a premature reaction, polylactic acid and the polyepoxide modifier are first mixed at a relatively low temperature (s). However, in order to induce cleavage of the main chain of polylactic acid, relatively high shear rates can be applied during mixing, and this leads to the fact that more hydroxyl and / or carboxylic groups can then react with the polyepoxide modifier. Upon completion of mixing, for extrusion of the mixed composition, a temperature (s) can be chosen at which the composition melts and initiates the reaction of the polyepoxide modifier with hydroxyl and / or carboxylic groups of polylactic acid. The authors of the present invention, it was found that the selective control of the parameters of the method allows to obtain fibers with good mechanical properties, which are manifested both during and after receiving the fiber by spinning from the melt.

Various embodiments of the present invention are described in more detail below.

I. Thermoplastic composition

A. Polylactic acid

Polylactic acid is usually obtained from the monomer units of any isomer of lactic acid, for example, levorotatory lactic acid ("L-lactic acid"), dextrorotatory lactic acid ("D-lactic acid"), meso-lactic acid, or mixtures thereof. Monomeric blocks can also be obtained from the anhydrides of any isomers of lactic acid, which include L-lactide, D-lactide, meso-lactide, or mixtures thereof. It is also possible to use cyclic dimers of said lactic acids and / or lactides. For the polymerization of lactic acid, any known polymerization method, for example, polycondensation or ring opening polymerization, can be used. A small amount of macromolecule chain extender (e.g., diisocyanate derivative, epoxy compound or acid anhydride) may also be used. The polylactic acid may be a homopolymer or a copolymer, for example, a copolymer containing monomeric blocks derived from L-lactic acid and monomeric blocks derived from D-lactic acid. Optionally, the content of one of the monomer units derived from L-lactic acid and the monomer units derived from D-lactic acid is preferably approximately 85 mol%. or more, in some embodiments, the implementation of approximately 90 mol%. or more, and in some embodiments, implementation, approximately 95 mol%. or more. Many polylactic acids, each of which includes monomeric blocks derived from L-lactic acid, and monomeric blocks derived from D-lactic acid, in various ratios, can be mixed with each other in arbitrary proportions. Of course, in order to achieve a certain beneficial effect, for example, to improve processing ability, fiber formation, etc., polylactic acid can also be mixed with other types of polymers (for example, polyolefins, polyesters, etc.).

In one specific embodiment, polylactic acid has the following generalized structure:

One specific embodiment of a suitable polylactic acid polymer that can be used according to the present invention is a commercially available product sold by Biomer, Inc., Krailling, Germany, under the name BIOMER ™ L9000. Other suitable polylactic acid polymers are provided by Natureworks LLC, Minnetonka, Minnesota (NATUREWORKS®) or Mitsui Chemical (LACEA ™). Other suitable types of polylactic acid are described in US 4,797,468; US 5,470,944; US 5,770,682; US 5821327; US 5880254 and US 6326458, the contents of which are fully incorporated into this description by reference for any purpose.

Typical melting points of polylactic acid are from about 140 ° C to about 260 ° C, in some embodiments, from about 150 ° C to about 250 ° C, and in some embodiments, from about 160 ° C to about 220 ° C. A useful property of such polylactic acids is their rapid biodegradation. The glass transition temperature ("T _g ") of polylactic acid can be relatively high, for example, from about 40 ° C to about 80 ° C, in some embodiments, from about 50 ° C to about 80 ° C, and in some embodiments, from about 55 ° C to approximately 65 ° C. As described in more detail above, the melting point and glass transition temperature can be determined by differential scanning calorimetry ("DSC") in accordance with ASTM D-3417.

The number average molecular weight ("M _n ") of polylactic acid is typically from about 40,000 to about 160,000 grams / mol, in some embodiments from about 50,000 to about 140,000 grams / mol, and in some embodiments from about 80,000 to about 120,000 grams / the mole. Similarly, the weight average molecular weight ("M _w ") of the polymer is usually from about 80,000 to about 200,000 grams / mol, in some embodiments from about 100,000 to about 180,000 grams / mol, and in some embodiments from about 110,000 to about 160,000 grams / mol. The ratio of the weight average molecular weight to number average molecular weight ("M _w / M _n "), i.e. the polydispersity index is also relatively low. For example, the polydispersity index is usually from about 1.0 to about 3.0, in some embodiments, from about 1.1 to about 2.0, and in some embodiments, from about 1.2 to about 1.8. The weight average and number average molecular weights can be determined by methods known to those skilled in the art.

Values of effective (apparent) viscosity of polylactic acid, determined at a temperature of 190 ° C and a shear rate of 1000 sec ^-1 , can be from about 50 to about 600 Pascal per second (Pa · s), in some embodiments, from about 100 to about 500 Pa · s, and in some embodiments, from about 200 to about 400 Pa · s. The melt flow rate of polylactic acid (dry matter), determined at a load of 2160 grams and a temperature of 190 ° C, can be from about 0.1 to about 40 grams in 10 minutes, in some embodiments, from about 0.5 to about 20 grams per 10 minutes, and in some embodiments, from about 5 to about 15 grams in 10 minutes.

B. Polyepoxide Modifier

A polyepoxide modifier is a polymer that on average contains at least two oxirane rings in one molecule. Not limited to any theory, it can be assumed that polyepoxide molecules under certain conditions can cause the polymer chain of polylactic acid to grow, which leads to an increase in the melt strength index, but does not significantly reduce the glass transition temperature. Extension of the chain can occur as a result of many different reactions. For example, a modifier may be involved in a nucleophilic ring opening reaction with a terminal carboxyl group of polylactic acid (formation of an ester group) or with a hydroxyl group (formation of an ether group). Adverse reactions involving oxazoline can also occur, leading to the formation of ester fragments. Carrying out such reactions can increase the molecular weight of polylactic acid, which can neutralize the decomposition effect, often observed during melt processing. Despite the desirability of proceeding with the reactions described above with polylactic acid, the inventors of the present invention have found that a too deep reaction can lead to the formation of cross-links between the main chains of polylactic acid. If the cross-linking reactions proceed to a significant degree, the resulting polymer mixture may become brittle, which makes it difficult to stretch it in the form of fibers of the required strength and with the required elongation ability. In this regard, the inventors of the present invention have found that it is particularly preferable to use polyepoxide modifiers having a relatively low degree of functionalization with epoxy groups, where functionalization with epoxy groups is a quantitative characteristic that can be expressed as an "equivalent mass of epoxide." The equivalent mass of the epoxide reflects the amount of polymer that contains one epoxy group, and can be calculated as the ratio of the number average molecular weight of the modifier to the number of epoxy groups in the molecule. The number average molecular weight of the polyepoxide modifier of the present invention is typically from about 7,500 to about 250,000 grams per mole, in some embodiments, from about 15,000 to about 150,000 grams per mole, and in some embodiments, from about 20,000 to 100,000 grams per mole, and the polydispersity is usually from 2.5 to 7. The polyepoxide modifier may contain less than 50, in some embodiments, from 5 to 45, and in some embodiments 15 to 40 epoxy groups. In turn, the equivalent mass of the epoxide may be less than about 15,000 grams per mole, in some embodiments, from about 200 to about 10,000 grams per mole, and in some embodiments, from about 500 to about 7000 grams per mole.

The polyepoxide can be either linear (unbranched) or branched, be a homopolymer or copolymer (e.g., a disordered polymer, graft copolymer, block copolymer, etc.) containing terminal epoxy groups, skeletal oxirane blocks and / or side epoxy groups. The monomers used to produce such polyepoxides may vary. For example, in one specific embodiment, the polyepoxide modifier comprises at least one epoxy functionalized (meth) acrylic monomer component. As used herein, the term “(meth) acrylic” includes acrylic and methacrylic monomers, as well as their salts or esters, such as acrylate and methacrylate monomers. Non-limiting examples of suitable epoxide functionalized (meth) acrylic monomers may include monomers containing 1,2-epoxy groups, for example glycidyl acrylate and glycidyl methacrylate. Other suitable epoxide functionalized monomers include allyl glycidyl ether, glycidyl ethacrylate and glycidyl isoconate.

As indicated above, the polyepoxide usually has a relatively high molecular weight, that is, its addition provides not only the extension of the chain of polylactic acid, but also allows you to achieve the desired morphology of the mixture, as described in more detail below. The melt flow rate of the polymer thus obtained, determined at a load of 2160 grams and a temperature of 190 ° C, is usually in the range of from about 10 to about 200 grams in 10 minutes, in some embodiments, from about 40 to about 150 grams in 10 minutes, and in some embodiments, from about 60 to about 120 grams in 10 minutes.

If necessary, to achieve the desired molecular weight, additional monomers may also be included in the polyepoxide. Such monomers may be different and may include, for example, ester monomers, (meth) acrylic monomers, olefin monomers, amide monomers, etc. For example, in one specific embodiment, the polyepoxide modifier comprises at least one linear or branched α-olefin monomer, for example, a monomer comprising from 2 to 20 carbon atoms, and preferably from 2 to 8 carbon atoms. Specific examples include ethylene, propylene, 1-butene; 3-methyl-1-butene; 3,3-dimethyl-1-butene; 1-pentene; 1-pentene comprising one or more methyl, ethyl or propyl substituents; 1-hexene comprising one or more methyl, ethyl or propyl substituents; 1-heptene comprising one or more methyl, ethyl or propyl substituents; 1-octene comprising one or more methyl, ethyl or propyl substituents; 1-nonene comprising one or more methyl, ethyl or propyl substituents; substituted with ethyl, methyl or two methyl 1-decene; 1-dodecene; and styrene. Particularly preferred α-olefin comonomers are ethylene and propylene.

Another suitable monomer may include an (meth) acrylic monomer not functionalized with epoxide. Examples of such (meth) acrylic monomers may include methyl acrylate, ethyl acrylate, n-propyl acrylate, isopropyl acrylate, n-butyl acrylate, sec-butyl acrylate, isobutyl acrylate, tert-butyl acrylate, n-amyl acrylate, isoamyl acrylate, isobornyl acrylate, 2-isobenyl acrylate, 2-isobenyl acrylate, 2-isobenyl acrylate, 2 ethylhexyl acrylate, n-octyl acrylate, n-decyl acrylate, methyl cyclohexyl acrylate, cyclopentyl acrylate, cyclohexyl acrylate, methyl methacrylate, ethyl methacrylate, 2-hydroxyethyl methacrylate, n-propyl methacrylate, n-butyl methacrylate, isomethyl acrylate, isopropylmethyl acrylate acrylate, n-hexyl methacrylate, izoamilmetakrilat, sec-butyl, tert-butyl methacrylate, 2-ethylbutyl, metiltsiklogeksilmetakrilat, tsinnamilmetakrilat, krotilmetakrilat, cyclohexyl, tsiklopentilmetakrilat, 2-ethoxyethyl methacrylate, isobornyl methacrylate, etc., and combinations thereof.

In one particularly preferred embodiment of the present invention, the polyepoxide modifier is a ternary polymer derived from an epoxide functionalized (meth) acrylic monomer component, an α-olefin monomer component and an epoxy-free (meth) acrylic monomer component. For example, the polyepoxide modifier may be a triple copolymer of ethylene, methyl acrylate and glycidyl methacrylate having the following structure:

where x, y and z are 1 or more.

The polymer can be prepared from epoxy functionalized monomer using a variety of known techniques. For example, a monomer containing polar functional groups can be grafted onto the polymer backbone, whereby a graft copolymer can be obtained. Graft polymerization techniques are well known in the art and are described, for example, in US Pat. No. 5,179,164, the contents of which are incorporated herein by reference for all purposes. In other embodiments, using known methods of free radical polymerization, for example, reactions taking place at high pressure, reactions taking place in the presence of Ziegler-Natta catalyst systems, catalyst systems with one active center (e.g., metallocene catalyst), etc., can copolymerization of a monomer containing functional epoxy groups with another monomer to form a block copolymer or a disordered copolymer.

The relative fraction of the monomer component (s) can be selected so as to achieve a certain balance between the reactivity of the epoxy groups and the melt flow rate. In particular, a high content of epoxy monomer can lead to high reactivity in reactions with polylactic acid, but its too high content can reduce the melt flow rate to such an extent that the use of a polyepoxide modifier will reduce the melt strength of the polymer mixture. Thus, in most embodiments, the epoxide functionalized (meth) acrylic monomer (s) comprises from about 1 wt.% To about 25 wt.%, In some embodiments, from about 2 wt.% To about 20 wt.%, And in some embodiments, from about 4% to about 15% by weight of the copolymer. Similarly, the α-olefin monomer (s) may be from about 55 wt.% To about 95 wt.%, In some embodiments, from about 60 wt.% To about 90 wt.%, And in some embodiments, from about 65 wt. % to about 85% by weight of the copolymer. If other monomer components are used (for example, not containing epoxy functional groups (meth) acrylic monomers), they can be from about 5 wt.% To about 35 wt.%, In some embodiments, from about 8 wt.% To about 30 wt.%, and in some embodiments, from about 10 wt.% to about 25 wt.% by weight of the copolymer. One specific example of a suitable polyepoxide modifier that can be used in the practice of the present invention is a commercially available product sold by Arkema under the name Lotader® AX8950. The melt flow rate of Lotader® AX8950 is from 70 to 100 g / 10 min., The content of glycidyl methacrylate monomer in it is from 7 wt.% To 11 wt.%, The content of methyl acrylate monomer is from 13 wt.% To 17 wt.%, And the content of ethylene monomer is from 72 wt.% to 80 wt.%

In addition to choosing the type and relative content of monomers used to produce the polyepoxide modifier, the total percentage modifier can also be selected to achieve the desired properties. For example, if the level of modification is too low, then the required degree of increase in melt strength and improvement of mechanical properties may not be achieved. However, the authors of the present invention also found that if the level of modification is too high, then the stretching of the fibers can be limited as a result of strong intermolecular interaction (for example, cross-linking) and the formation of a physical network by epoxy functional groups. Thus, the amount of polyepoxide modifier used is typically from about 0.01 wt.% To about 10 wt.%, In some embodiments, from about 0.05 wt.% To about 5 wt.%, In some embodiments, from about 0 , 1 wt.% To about 1.5 wt.%, And in some embodiments, from about 0.2 wt.% To about 0.8 wt.% Of the mass of polylactic acid in the composition. Depending on the type and amount of other components used, the concentration of the polyepoxide modifier in the entire thermoplastic composition may be within the ranges indicated above or be less than the indicated values. For example, in some embodiments, the polyepoxide modifier is from about 0.01 wt.% To about 10 wt.%, In some embodiments, from about 0.05 wt.% To about 5 wt.%, In some embodiments, from about 0.1 wt.% To about 1.5 wt.%, And in some embodiments, from about 0.2 wt.% To about 0.8 wt.% Of the total weight of the composition. Similarly, polylactic acid typically comprises about 70 wt.% Or more, in some embodiments, from about 80 wt.% To about 99 wt.%, And in some embodiments, from about 85 wt.% To about 95 wt.% From mass of the composition.

C. Strengthening additive

Although not necessary, in order to increase the melt strength and stability of the composition during spinning during the production of fibers, the thermoplastic composition according to the present invention may also contain one or more polymer reinforcing additives. One of the beneficial effects of the present invention is that when using such additives, the hydrophobic part of the polyepoxide modifier (e.g., olefin monomer) can also interact with the reinforcing additive to form a substantially homogeneous reinforcing additive compatible with the other nanodispersion components in the polylactic acid matrix. This uniform distribution allows to give the obtained fibers the required mechanical properties.

Due to its polymer structure, the reinforcing additive has a relatively high molecular weight and can contribute to increasing the melt strength and stability of the thermoplastic composition. It is usually required that the polymer reinforcing additive is not miscible with polylactic acid. In this case, the reinforcing additive can be dispersed in the form of discrete phase domains in the continuous phase of polylactic acid. Discrete domains can absorb energy arising from stresses during elongation of the composition during fiber drawing, which increases the overall stiffness and strength of the resulting fibers. Although polymers are typically immiscible, a reinforcing additive may be selected whose solubility parameter is relatively close to the solubility parameter of polylactic acid. Such compliance usually increases interfacial adhesion and improves physical interaction at the boundaries of the discrete and continuous phases and, thus, reduces the likelihood of fracture of the composition under tension. Thus, the ratio of the solubility parameter of polylactic acid to the solubility parameter of the hardening additive is usually from about 0.5 to about 1.5, and in some embodiments, from about 0.8 to about 1.2. For example, the solubility parameter of the polymer reinforcing agent may be from about 15 to about 30 MJ ^1/2 / m ^3/2 , and in some embodiments, from about 18 to about 22 MJ ^1/2 / m ^3/2 , while the solubility parameter of polylactic acid is approximately 20.5 MJ ^1/2 / m ^3/2 . The term “solubility parameter” as used herein means “Hildebrand solubility parameter”, which is equal to the square root of the cohesion energy density and can be calculated from the following equation:

Where:

ΔHv = heat of vaporization

R = universal gas constant

T = Temperature

Vm = Molecular Volume

Hildebrand's solubility parameters for many polymers are given in Solubility Handbook of Plastics, Wyeych (2004), the entire contents of which are incorporated herein by reference.

The choice of polymer reinforcing additives can also provide a certain melt flow rate (or viscosity), which contributes to the adequate retention of the shape of discrete domains. For example, if the melt flow rate of the reinforcing additive is too large, then the flow and distribution of the additive in the continuous phase becomes uncontrollable. In this case, layered or lamellar domains are formed that poorly retain their shape, which are very likely to prematurely collapse during fiber stretching. On the contrary, if the melt flow rate of the reinforcing additive is too small, the additive accumulates, forming very large elliptical domains that are poorly dispersed during mixing. This can lead to an uneven distribution of the hardening additive throughout the mass of the continuous phase. Thus, the ratio of the melt flow rate of the reinforcing additive to the melt flow rate of polylactic acid is usually from about 0.2 to about 8, in some embodiments from about 0.5 to about 6, and in some embodiments, from about 1 to about 5. The melt flow rate of the polymer reinforcing additive, measured at a load of 2160 grams and a temperature of 190 ° C, can be, for example, from about 0.1 to about 250 grams per 10 minutes, in some embodiments, from about 0.5 to about 200 grams in 10 minutes, and in some embodiments, from about 5 to about 150 grams in 10 minutes.

In addition to the above properties, the mechanical characteristics of the polymer reinforcing additives can also be selected in such a way as to provide the desired increase in fiber stiffness. For example, the Young's modulus of elasticity of the reinforcing additive may be relatively lower than the elastic modulus of polylactic acid. For example, the characteristic ratio of the elastic modulus of polylactic acid to the modulus of the reinforcing additive is from about 1 to about 250, in some embodiments, from about 2 to about 100, and in some embodiments, from about 2 to about 50. The elastic modulus of the reinforcing additive may, for example from about 2 to about 500 mega Pascal (MPa), in some embodiments, from about 5 to about 300 MPa, and in some embodiments, wasp estvleniya from about 10 to about 200 MPa. In contrast, the elastic modulus of polylactic acid is usually from about 800 MPa to about 2000 MPa. In addition, the maximum elongation (i.e., percent elongation of the polymer at maximum load) of the polymer reinforcing additive may also exceed the maximum elongation of polylactic acid. For example, the maximum elongation of the polymer reinforcing agent of the present invention may be about 50% or more, in some embodiments, about 100% or more, in some embodiments, from about 100% to about 2000%, and in some embodiments, from about 250% up to about 1500%.

According to the invention, a plurality of polymer additives having the properties described above can be used; however, particularly suitable examples of such polymers may include polyolefins (eg, polyethylene, polypropylene, polybutylene, etc.); polytetrafluoroethylene; polyesters (e.g., reusable polyester, polyethylene terephthalate, etc.); polyvinyl acetates (e.g. polyethylene vinyl acetate, polyvinyl chloride acetate, etc.); polyvinyl alcohols (e.g. polyvinyl alcohol, polyethylene vinyl alcohol), etc .; polyvinyl butyral; acrylic polymers (e.g. polyacrylate, polymethyl acrylate, polymethyl methacrylate, etc.); polyamides (e.g. nylon); polyvinyl chloride; polyvinylidene chloride; polystyrenes; polyurethanes; etc. Suitable polyolefins may, for example, include ethylene polymers (e.g., low density polyethylene ("HDPE"), high density polyethylene ("PVP"), linear low density polyethylene ("LDL"), etc., propylene homopolymers (e.g. syndiotactic, atactic, isotactic, etc.), propylene copolymers, etc.

In one specific embodiment, the polymer is a propylene polymer, for example, a homopolypropylene or a propylene copolymer. The propylene polymer can be, for example, a substantially isotactic polypropylene homopolymer or copolymer containing about 10 wt.% Or less of another monomer, i.e. at least about 90 wt.% propylene. The melting point of such homopolymers can be from about 160 ° C to about 170 ° C.

In another embodiment, the polyolefin may be a copolymer of ethylene or propylene and another α-olefin, such as a C ₃ -C ₂₀ α-olefin or a C ₃ -C ₁₂ α-olefin. Specific examples of suitable α-olefins include 1-butene; 3-methyl-1-butene; 3,3-dimethyl-1-butene; 1-pentene; 1-pentene having one or more methyl, ethyl or propyl substituents; 1-hexene having one or more methyl, ethyl or propyl substituents; 1-heptene having one or more methyl, ethyl or propyl substituents; 1-octene having one or more methyl, ethyl or propyl substituents; 1-nonene having one or more methyl, ethyl or propyl substituents; substituted with ethyl, methyl or two methyl 1-decene; 1-dodecene; and styrene. Particularly preferred α-olefin comonomers are 1-butene, 1-hexene and 1-octene. The content of ethylene or propylene in such copolymers may be from about 60 mol%. to about 99 mol%, in some embodiments, from about 80 mol%. to about 98.5 mol%, and in some embodiments, from about 87 mol%. up to approximately 97.5 mol%. Similarly, the content of α-olefin may be from about 1 mol%. to about 40 mol%, in some embodiments, from about 1.5 mol%. to about 15 mol%, and in some embodiments, from about 2.5 mol%. up to about 13 mol%.

Examples of olefin copolymers suitable for use in accordance with the present invention include ethylene-based copolymers sold by ExxonMobil Chemical Company, Houston, Texas, under the name EXACT ™. Other suitable ethylene copolymers are supplied by Dow Chemical Company, Midland, MI, under the names ENGAGE ™, AFFINITY ™, DOWLEX ™ (linear low density polyethylene, abbreviated as LDL) and ATTANE ™ (ultra low density polyethylene, abbreviated as PSNP). Other suitable ethylene polymers are described in US Pat. No. 4,937,299 to Ewen et al .; US 5218071. Tsutsui et al .; US 5272236, Lai, et al. and US 5278272, Lai, et al., the contents of which are fully incorporated into this description by reference for any purpose. Suitable propylene copolymers are also available from ExxonMobil Chemical Co., [Houston, Texas, under the name VISTAMAXX ™; Atofina Chemicals, Feluy, Belgium, under the name FINA ™ (e.g. 8573); Mitsui Petrochemical Industries, under the name TAFMER ™; and Dow Chemical Co., Midland, MI, under the name VERSIFY ™. Other examples of suitable propylene polymers are described in US Pat. Nos. 6,500,563, Datta, et al .; US 5539056, Yanq, et al. and US 5596052, Resconi. et al., the contents of which are fully incorporated into this description by reference for any purpose.

To obtain olefin copolymers can be applied many known methods. For example, olefin polymers can be prepared using a free radical polymerization catalyst or a coordination catalyst (e.g., Ziegler-Natta catalyst). Preferably, the olefin polymer is prepared using a coordination catalyst with one active site, for example, a metallocene catalyst. Using such a catalytic system, ethylene copolymers are obtained in which the comonomer is randomly distributed along the molecular chain and uniformly distributed over all fractions with different molecular weights. Polyolefins obtained using a metallocene catalyst are described, for example, in patents US 5571619, McAlpin et al .; US 5322728, Davis et al .; US 5472775, Obiieski et al .; US 5,272,236, Lai et al. and US 6090325, Wheat, et al., the contents of which are fully incorporated into this description by reference for any purpose. Examples of metallocene catalysts include bis (n-butylcyclopentadienyl) titanium dichloride, bis (n-butylcyclopentadienyl) zirconium dichloride, scandium bis (cyclopentadienyl) chloride, bis (indenyl) zirconium dichloride, bis (methylcyclopentadienyl) titanium dichloride dichloride cobaltocene, cyclopentadienyl titanium trichloride, ferrocene, hafnocene dichloride, isopropyl (cyclopentadienyl-1-fluorenyl) zirconium dichloride, molybdocene dichloride, nickelocene, niobocene dichloride, rutenocene, titanocene dichloride, chlorofluoride on, zirconocene dichloride, etc. Polymers prepared using metallocene catalysts typically have a narrow range of molecular weights. For example, polymers prepared using metallocene catalysts may have polydispersity coefficients (M _w / M _n ) of less than 4, controlled distribution of short chain branching, and controlled isotacticity.

If a reinforcing additive is used, its amount is usually from about 1 wt.% To about 25 wt.%, In some embodiments, from about 2 wt.% To about 20 wt.%, And in some embodiments, from about 5 wt. % to about 15 wt.% by weight of the thermoplastic composition.

D. Other components

One of the positive aspects of the present invention is the possibility of obtaining satisfactory mechanical properties (for example, elongation) in the absence of traditional plasticizers, such as alkylene glycols (for example, polyethylene glycols, for example, products supplied by Dow Chemical under the name Carbowax ™), alkanediols and alkylene oxides containing one or more hydroxyl groups that react with ester bonds of polylactic acid, causing its hydrolytic decomposition. Other examples of such plasticizers are described in application US 2010/0048082, Topolkaraev. et al., the contents of which are fully incorporated into this description by reference for all purposes. Thus, the thermoplastic composition of the present invention may essentially not contain such plasticizers. However, it should be understood that in some embodiments, the implementation of the present invention can be used plasticizers. However, the amount of plasticizers, if added, is usually less than about 10 wt.%, In some embodiments, from about 0.1 wt.% To about 5 wt.%, And in some embodiments, from about 0.2 wt.% To about 2 wt.% By weight of the thermoplastic composition.

Of course, for many different reasons, other ingredients may be added to the composition. For example, materials that may be added include, but are not limited to, catalysts, pigments, antioxidants, stabilizers, surfactants, paraffins (waxes), flow activators, solid solvents, nucleating agents (e.g. titanium dioxide, calcium carbonate, etc.) etc.), powders and other materials added to increase the processing ability of the thermoplastic composition. If the materials mentioned are used, it is usually preferable that the amounts of such additional ingredients be minimized to ensure optimum compatibility and cost-effectiveness. So, for example, it is usually preferred that the content of such ingredients is less than about 10 wt.%, In some embodiments, less than about 8 wt.%, And in some embodiments, less than about 5 wt.% By weight of the thermoplastic composition.

It should also be understood that other components may be included in the thermoplastic composition. One of the possible components that can be used is an additional biodegradable polyester, including aliphatic polyesters, for example polycaprolactone, polyetheramides, modified polyethylene terephthalate, polylactic acid (PMA) and its copolymers, polylactic acid based triple copolymers, polyglycolic acid, for example polyalkylene carbonates (e.g. , polyethylene carbonate), poly-3-hydroxybutyrate (PHB), poly-3-hydroxyvalerate (PGV), a copolymer of 3-hydroxybutyrate and 4-hydroxybutyrate, copolymers 3-hydroxybutyrate and 3-hydroxyvalerate (PHBV), a copolymer of 3-hydroxybutyrate and 3-hydroxyhexanoate, a copolymer of 3-hydroxybutyrate and 3-hydroxyoctanoate, a copolymer of 3-hydroxybutyrate and 3-hydroxydecanoate, a copolymer of 3-hydroxybutyrate and 3-hydroxyhydroxyate succinate base (salts or esters of succinic acid) (for example, polybutylene succinate, polybutylene succinate adipate, polyethylene succinate, etc.); aliphatic-aromatic ester copolymers (e.g., polybutylene adipate-terephthalate, polyethylene adipate-terephthalate, polyethylene adipate-isophthalate, polybutylene adipate-isophthalate, etc.), etc.

II. Mixing

Pure polylactic acid usually absorbs water from the environment, as a result of which the moisture content in it can be from about 500 to 600 ppm or even more, calculated on the dry weight of the original polylactic acid. The moisture content can be determined by many different methods known in the art, for example, in accordance with ASTM D 7191-05, as described above. Since the presence of water during melt processing can lead to hydrolytic decomposition of polylactic acid and a decrease in its molecular weight, it is sometimes desirable to dry polylactic acid before mixing. For example, for most embodiments, it is desirable for the polylactic acid to have a moisture content of about 200 ppm or less before mixing with the polyepoxide modifier, in some embodiments, from about 1 to about 100 ppm, and in some embodiments, from about 2 to about 80 ppm. Drying of polylactic acid can be carried out, for example, at a temperature of from about 50 ° C to about 100 ° C, and in some embodiments, from about 70 ° C to about 80 ° C.

Mixing the components of the thermoplastic composition can be done using a variety of known techniques. For example, in one embodiment, the supply of raw materials (for example, polylactic acid and polyepoxide modifier) can be performed individually or in combination. For example, the raw materials may first be mixed with each other in a dry state to form a substantially homogeneous dry mixture. Similarly, raw materials can be fed both simultaneously and sequentially to a melt molding apparatus in which dispersing mixing of materials is carried out. Methods of batch and / or continuous melt molding may be used. For example, a mixer / kneading machine, a Banbury mixer, a continuous Farrel mixer, a single screw extruder, a twin screw extruder, a roller mill, etc. can be used to mix materials and melt molding. A particularly suitable melt molding device may be an extruder with two screws rotating in the same direction (for example, an extruder ZSK-30 supplied by Werner & Pfleiderer Corporation, Ramsey, New Jersey, or an extruder Thermo Prism ™ USALAB 16 supplied by Thermo Electron Corp ., Stone, England). Such extruders may include inlets and gas outlets and provide intensive mixing with high distribution and dispersion efficiencies. For example, polylactic acid and the polyepoxide modifier can be sent to the same or different inlets of a twin-screw extruder and mixed in the molten state to form a substantially homogeneous molten mixture. If necessary, other additives (for example, reinforcing additives) can also be introduced into the polymer melt and / or separately introduced into the extruder through holes located in different sections along the length of the extruder. Alternatively, the additives may be mixed with polylactic acid and / or the polyspoxide modifier in advance.

Regardless of the choice of a particular processing method, the raw materials are mixed at high shear / pressure and low temperature, sufficient to ensure sufficient dispersion, but at which there is no noticeable premature reaction of the polyepoxide modifier with polylactic acid. For example, mixing is usually carried out at a temperature above the melting point of polylactic acid, but lower than the temperature, leading to a noticeable initiation of a reaction with polyepoxide modifiers (e.g., approximately 230 ° C), e.g. in some embodiments, from about 180 ° C to about 220 ° C, and in some embodiments, from about 185 ° C to about 215 ° C. Similarly, the apparent shear rate during melt molding may be from about 100 seconds ^-1 to about 10,000 seconds ^-1 , in some embodiments, from about 200 seconds ^-1 to about 5000 seconds ^-1 , and in some embodiments, from about 500 seconds ^-1 to about 1200 seconds ^-1 . The apparent shear rate is determined by equation 4 Q / πR ³ , in which O is the volumetric flow rate ("m ³ / s") of the polymer melt, and R is the radius ("m") of the capillary (for example, the extruder head hole), through which flows the molten polymer. Of course, in order to achieve the required degree of homogeneity, other variable parameters can also be controlled, for example, the residence time of the material in the device during melt molding, which is inversely proportional to the transmission rate of the material.

The inventors of the present invention have found that the selective control of polyepoxide parameters (e.g., activity, molecular weight, etc.) and certain melt mixing conditions results in a morphology that increases the polyepoxide reactivity in reactions with polylactic acid. In particular, the resulting morphology may include many domains of the discrete phase of the polyepoxide modifier distributed in a continuous matrix of polylactic acid. Domains can have many different shapes, for example, elliptical, spherical, cylindrical, etc. However, regardless of the shape, the size of a single domain after mixing is sufficiently small, which provides a large surface area for the subsequent reaction with polylactic acid. For example, the domain size (eg, length) is usually from about 10 to about 1000 nanometers, in some embodiments from about 20 to about 800 nanometers, in some embodiments from about 40 to about 600 nanometers, and in some embodiments from about 50 to about 400 nanometers. Optionally, the reinforcing agent present can also form discrete domains in a polylactic acid matrix. If they form, then such domains are usually larger than the domains formed by polyepoxide. For example, the size (eg, length) of the domains formed by the reinforcing additive may be from about 0.5 μm to about 30 μm, and in some embodiments, from about 1 μm to about 10 μm. Of course, it should also be understood that the domains can be formed by a combination of polyepoxide, a reinforcing additive and / or other components of the mixture.

III. Reaction Procedure

The reaction of the mixture of the polyepoxide modifier and polylactic acid is carried out while the starting polymers are in the molten state ("melt processing"), which minimizes the need for removal of additional solvents and / or solvent. In particular, the mixture may be fed into an extruder (e.g., a single screw extruder), which comprises a rotatable screw mounted in a housing (e.g., a cylindrical housing), which may be heated. The mixture is passed in the direction of the process flow from the supply part to the outlet part under the action of the force created by the rotation of the screw. Such screw extruders are usually divided into three sections along the length of the screw. The first section is a feeding section in which the solid material is captured by the screw. The second section is a melting section in which most of the solid materials are melted. To intensify the melting of the polymer, the screw inside this section usually has a conical shape. The third section is a mixing section, during operation of which the supply of molten material occurs at a constant speed in the extrusion stage. The choice of screw configuration is not particularly critical for the present invention, and the screw may comprise any number and / or any orientation of thread or grooves known in the art.

Before being discharged from the extruder through the extrusion head, the molten polymer can also be passed through one or more nets (“mesh seal or mesh set”) located in the housing, which are optionally reinforced with a distribution grid. In addition to removing contaminants and unmelted solids, the mesh seal / distribution grid assembly helps create backpressure in the housing, which improves melt uniformity and polymer mixing. The pressure in the head can be adjusted by changing the configuration of the mesh seal (number of grids, size of the holes of the grids, etc.). The mesh seal may include, for example, from 2 to 15 grids, in some embodiments, from 3 to 10 grids, and in some embodiments, from 4 to 8 grids. If multiple grids are used, the sizes of the openings of the grids located upstream are usually sufficient to collect only large particles, and the sizes of the holes of the grids located sequentially downstream allow collecting smaller particles. Although it is possible to use grids of various sizes, to create a sufficiently high back pressure in the housing, it is usually desirable that the seal contains at least one grid with holes of a relatively small size. For example, the average width (or diameter) of the mesh openings may be about 100 micrometers or less, in some embodiments, about 75 micrometers or less, and in some embodiments, from about 1 to about 50 micrometers. Preferably, the seal includes a plurality of nets (e.g., 3 or more) with holes of a similar size.

The screw speed can also be selected so as to provide the desired residence time, shear rate, melt processing temperature, etc. For example, the screw speed may be from about 50 to about 200 revolutions per minute ("rpm"), in some embodiments, from about 70 to about 150 rpm, and in some embodiments, from about 80 to about 120 rpm min In this case, temperatures can develop that are higher than the temperatures commonly used for extruding polylactic acid and high enough to initiate a reaction with a polyepoxide modifier, for example, exceeding approximately 230 ° C. For example, one or a plurality of zones can be created in the extruder, in at least one of which a temperature of from about 230 ° C to about 350 ° C is created, in some embodiments, from about 235 ° C to about 300 ° C, and in some embodiments, from about 240 ° C to about 280 ° C.

The melt shear rate and, in turn, the depth of reaction initiation can also be increased by installing one or more distribution and / or dispersion mixing elements in the mixing section of the extruder. Suitable distribution mixing elements for single screw extruders may include, for example, Saxon, Dulmage mixing elements, rotary vane mixers, etc. Similarly, suitable dispersion mixing elements may include mixers including an auger with an additional Blister ring, Leroy / Maddock mixing elements, CRD mixing elements, etc. It is well known in the art that the mixing intensity can be further increased by installing pins (rods) in the device body that crush and reorient the polymer melt, for example, pins installed in the extruders of Buss kneading machines, rotary cavity faucets and vortex mixers with pins engaging (eng. Vortex Intermeshing Pin, abbreviated VIP). Regardless of the type of particular elements selected, the use of one or more mixing elements can create high shear rates of the melt, contributing to the initiation of the desired reaction. Typically, the apparent shear rate during melt processing may be from about 100 seconds ^-1 to about 10,000 seconds ^-1 , in some embodiments, from about 200 seconds ^-1 to about 5000 seconds ^-1 , and in some embodiments, from about 500 seconds ^-1 to about 1200 seconds ^-1 . Of course, to achieve the desired depth of the reaction, you can adjust other parameters, for example, the residence time during processing in the melt, which is inversely proportional to the transmission rate.

The authors of the present invention also found that in order to achieve the desired depth of the reaction, in addition to controlling the shear parameters, it is also possible to control the moisture content in the precursor mixture. Not limited to any theory, it can be assumed that in the reaction of the polyepoxide with polylactic acid, water acts as a catalyst. However, too high a moisture content can lead to the decomposition of polylactic acid and a decrease in its molecular weight. In this regard, it has been found by the present inventors that the moisture content of the precursor mixture can be brought to values of from about 100 to about 500 ppm, in some embodiments, from about 125 to about 400 ppm, and in in some embodiments, from about 150 to about 300 ppm. Such moisture values can be obtained after drying, for example, at a temperature of from about 40 ° C to about 80 ° C, and in some embodiments, from about 50 ° C to about 70 ° C.

Despite the fact that the reacted polylactic acid differs from the starting polymer in some properties, it can nevertheless preserve other properties of the starting polymer. For example, since the thermoplastic composition used to make the fibers typically does not contain a plasticizer, the glass transition temperature (T _g ) of the reacted composition usually remains the same as the glass transition temperature of polylactic acid. That is, the T _{g of the} reacted thermoplastic composition may be from about 50 ° C to about 80 ° C, and in some embodiments, from about 55 ° C to about 65 ° C. The melting temperature of the thermoplastic composition may also be from about 150 ° C to about 250 ° C, and in some embodiments, from about 160 ° C to about 220 ° C.

III. Fiber formation

The fibers obtained from the reacted thermoplastic composition can usually have any desired configuration, examples of which include single-component and multicomponent fibers (for example, shell-core configuration, configuration along each other, configuration of a “segmented cake”, configuration “island in the sea”, etc. d.). In some embodiments, to further increase strength and improve other mechanical properties, the fibers may contain as a component (e.g., bicomponent fibers) or a constituent material (e.g., fibers comprising two constituent substances) one or more additional polymer. For example, the thermoplastic composition may form the sheath / core component of the bicomponent fiber, while the additional polymer may form the core component or vice versa. The additional polymer may be a thermoplastic polymer that is generally not considered biodegradable, for example, a polyolefin, for example, polyethylene, polypropylene, polybutylene, etc .; polytetrafluoroethylene; polyester, for example polyethylene terephthalate, etc .; polyvinyl acetate; polyvinyl chloride acetate; polyvinyl butyral; acrylic polymer, for example, polyacrylate, polymethyl acrylate, polymethyl methacrylate, etc .; polyamide, for example, nylon; polyvinyl chloride; polyvinylidene chloride; polystyrene; polyvinyl alcohol; and polyurethane. However, it is more desirable that the additional polymer be biodegradable, for example, include aliphatic polyesters, for example, polyetheramides, modified polyethylene terephthalate, polyglycolic acid, polyalkylene carbonates (e.g. polyethylene carbonate), polyhydroxyalkanoates (PHA), polyhydroxybutyrates (PHBV) , copolymers of polyhydroxybutyrate and hydroxyvalerate (PHBV) and polycaprolactone, and succinate-based aliphatic polymers (e.g. polybutylene succinate, polybutylene succinate-a Ipat and polyethylene succinate); aromatic polyesters; or other copolymers of aliphatic and aromatic esters.

Any of a variety of methods can be used to produce the fibers of the present invention. For example, the thermoplastic composition described above can be extruded through a die, subjected to rapid cooling, and pulled into a vertical shaft of a fiber drawing apparatus. The reaction of the polyepoxide modifier with polylactic acid can occur when the above steps are performed or before being introduced into the fiber spinning line. After forming, the fibers can be cut, resulting in a staple fiber, the average length of which is from about 3 to about 80 millimeters, in some embodiments, from about 4 to about 65 millimeters, and in some embodiments, from about 5 to about 50 millimeters . The staple fiber can then be introduced into a non-woven fabric known in the art, for example, non-woven carded fabric, non-woven fabric obtained by aerodynamic molding, etc. Fibers can also be deposited on a perforated surface on which they form a non-woven fabric.

So, Figure 1 shows in more detail one example of a method for producing fibers. In this particular embodiment, the pre-blended thermoplastic composition is extruded at a relatively high temperature to initiate a reaction between the epoxy functional groups of the modifier and polylactic acid, and also to form fibers. For example, a mixture of polylactic acid and a polyepoxide modifier is sent to the extruder 12 from the feed hopper 14. The mixture can be sent to the feed hopper 14 using any of the conventional techniques. As described in more detail above, the extruder 12 is heated to a temperature sufficient to extrude the molten polymer and to proceed the reaction between the polyepoxide modifier and polylactic acid. The extruded composition is then passed through a polymer conduit 16 into a die 18. For example, die 18 may include a housing containing a die assembly including a plurality of plates arranged one above the other, in which there are holes in a specific order through which polymer components can flow. The die 18 also includes holes arranged in one or more rows. When polymer is pressed through holes, filaments are formed, forming a curtain (bundle). The method 10 also employs a cooling blower 20 located near the curtain of fibers extracted from the die 18. The air coming from the cooling blower 20 cools the fibers extracted from the die 18. Cooling air can be directed from one side of the curtain of fibers, as shown in FIG. 1, or on both sides of a curtain of fibers.

After cooling, the fibers are pulled into the vertical shaft of the fiber traction device 22. Fiber traction devices or ejectors used in spinning fibers from polymer melts are well known in the art. Suitable fiber traction devices for use in the method of the present invention include an ejector for linear traction of fiber, similar to that described in US Pat. The fiber traction device 22 typically includes a long vertical shaft through which the fibers are pulled by suction air coming in from openings in the sides of the shaft and blown downward through the shaft. The suction air is sent to the fiber drawing device 22 by a heater or blower 24. Under the action of the suction air, the fibers and the surrounding air are transported through the fiber drawing device 22. The action of the gas flow causes the fibers to stretch or reduce their diameter, which increases the degree of orientation of the molecules or crystallinity of the polymers from which the fibers are formed. The fibers are passed through the outlet of the fiber stretcher 22 and stacked on the spinning disk 42. The high strength of the fibers according to the present invention allows the use of high degrees of stretch when implementing the method according to the present invention. The degree of elongation is calculated as the ratio of the linear velocity of the fibers after stretching (for example, the linear velocity of the spinning disk 42 or perforated surface (not shown)) to the linear velocity of the fibers after extrusion. For example, in some embodiments, the degree of traction can be calculated as follows:

Extent = A / B,

Where

A represents the linear speed of the fiber after stretching (i.e., the speed of the spinning disk), which can be directly measured; and

B is the linear velocity of the extruded fiber, which can be calculated as follows:

The linear velocity of the fiber coming from the extruder = C / (25 * π * D * E ² ), where

C is the flow rate through one hole (grams per minute);

D is the polymer melt density (grams per cubic centimeter); and

E is the diameter of the hole (in centimeters) through which the fiber is extruded. In some embodiments, the degree of stretching can range from about 200: 1 to about 7500: 1, in some embodiments, from about 500: 1 to about 6500: 1, and in some embodiments, from about 1000: 1 to about 6000: one.

Specialists in the art should understand that, if necessary, the fibers collected on the spinning disk 42 may optionally be subjected to additional processing and / or transformation (not shown). For example, the collected fibers can be subjected to "cold drawing" at a temperature below their softening temperature until the desired diameter is reached, after which they are corrugated, structured and / or cut into pieces of the required length to form staple fibers.

The inventors of the present invention have found that, regardless of the particular method of fiber formation, fiber elongation significantly increases the longitudinal size of the reacted discrete domains, that is, they usually have a linear elongated shape. The longitudinal dimensions of the extended domains can be approximately 10% or more, in some embodiments, by a value of from about 50% to about 1000%, and in some embodiments, by a size of from about 100% to about 500%, the longitudinal sizes of the domains can be larger than the fibers. The longitudinal size of the domains after stretching the fibers may, for example, be from about 10 microns to about 300 microns, in some embodiments, from about 40 microns to about 250 microns, and in some embodiments, from about 50 microns to about 200 microns. Domains can also have a relatively small thickness and, thus, have a small size in the direction perpendicular to the longitudinal direction (i.e., in the plane of the cross section). For example, the cross-sectional size may be from about 0.02 to about 75 micrometers, in some embodiments, from about 0.1 to about 40 micrometers, and in some embodiments, from 0.4 to about 20 micrometers. With this value, the aspect ratio for the domains (longitudinal to cross-sectional ratio) is from about 3 to about 200, in some embodiments from about 5 to about 100, and in some embodiments from about 5 to about 50.

The presence of such extended domains indicates the ability of the thermoplastic composition to absorb the energy released during the stretching of the fibers. In this case, the composition is not as fragile as a pure polymer, and thus, relaxation can occur when stress is applied, rather than destruction. During relaxation during application of stress, the polymer can continue to function as a supporting element, even after a substantial elongation of the fibers. In this regard, the fibers of the present invention may have an increased “maximum elongation”, i.e. percent fiber elongation at maximum load. For example, the maximum fiber elongation according to the present invention will burn approximately 25% or more, in some embodiments about 30% or more, in some embodiments from about 40% to about 350%, and in some embodiments from about 50% to about 250% Such elongation values can be obtained using fibers having different mean diameters, for example, from about 0.1 to about 50 micrometers in diameter, from about 1 to about 40 micrometers in some embodiments, from about 2 in some embodiments up to about 25 micrometers, and in some embodiments, from about 5 to about 15 micrometers.

Despite the ability to elongate under stress, the fibers of the present invention can also remain relatively strong. One parameter that indicates the relative strength of the fiber according to the present invention is “tensile strength”, which means the tensile strength of the fiber, expressed as the ratio of the applied force to the unit of linear density. For example, the tensile strength of the fibers according to the present invention can be from about 0.75 to about 6.0 gram-force ("g _f ") on denier (which is approximately 7.35 · 10 ^-3 to 58.8 · 10 ^-3 N denier), in some embodiments, from about 1.0 to about 4.5 g _f denier (which is approximately 9.8 · 10 ^-3 to 44.1 · 10 ^-3 N denier), and in some embodiments, from about 1.5 to about 4.0 g _f denier (which is about 14.75 · 10 ^-3 to 39.2 · 10 ^-3 N denier). Depending on the intended use, denier fibers may be different. Typically, fibers are obtained that have denier per thread (i.e., a unit of linear density is equal to a gram weight of 9,000 meters of fiber) of less than about 6, in some embodiments, less than about 3, and in some embodiments, from about 0.5 to about 3.

If necessary, a web with a coherent structure can also be formed from the fibers of the present invention, which is obtained by depositing the fibers randomly on the molding surface (optionally by applying a vacuum) and then bonding the resulting fabric using any known technique. For example, an infinite perforated molding surface may be installed under the fiber traction device onto which fibers coming from the outlet are deposited. A vacuum source can be installed under the molding surface, under the influence of which the fibers are drawn and the non-woven non-woven fabric is formed. After molding, the non-woven fabric can be bonded using any conventional technique, for example, using an adhesive or autogenous bonding (for example, fusion and / or auto-adhesion of fibers without the use of an additional adhesive). Autogenous bonding, for example, can be accomplished by contacting the fibers while they are still in a semi-molten or sticky state, or by simple mixing with polylactic acid (s) used to form the fibers, the tackifying polymer, and / or the solvent. Suitable autogenous bonding techniques may include ultrasonic bonding, thermal bonding, hot air bonding, calendaring, etc. For example, the web may be further bonded or a template may be extruded onto it in a thermomechanical manner, according to which the web is passed between the heated backup roll and the heated embossing roll. Any convex pattern can be applied to the embossing roll, which provides a web with the desired properties or appearance. It is preferable that a convex pattern be applied to the embossing roll defining a plurality of bonding portions that define a bonded region comprising from about 2% to 30% of the total area of the roll. Examples of patterns include, for example, the patterns described in US Pat. No. 3,855,046, Hansen et al., US Pat. No. 5,620,779, Lew et al., US Pat. No. 5,962,112, Havnes et al., US Pat. No. 6,093,665, Savovitz et al., Also in patents. US Pat. No. 4,288,267, Romano et al .; US 390708, US Brown: US 418305, Zander, et al .: US 384508, Zander, et al .; US 384819, Zander, et al .; US 358035, Zander, et al .: and US 315990, Blenke. et al., the contents of which are fully incorporated into this description by reference for any purpose. The pressure between the rolls can be from about 5 to about 2000 psi (which is about 89 to 3.57 · 10 ⁴ kg / m). The pressure between the rolls and the temperature of the rolls are set so as to obtain the desired properties or appearance of the web and maintain a fabric-like texture. As is well known to specialists in this field of technology, the required temperature and pressure can vary widely depending on many factors, non-limiting examples of which include the area of the template bonding, polymer properties, fiber properties and non-woven fabric properties.

In addition to spunbond webs, many other non-woven webs can also be obtained from the thermoplastic composition according to the present invention, for example, meltblown webs, bonded carded webs, wet formed webs, dry-formed webs, conformal webs, webs, hydraulically confused, etc. For example, a thermoplastic composition can be extruded through many small capillaries of a die into a gas stream (for example, air) converging at one point, moving at high speed, resulting in a reduction in fiber diameter. Then, the fibers obtained by the aerodynamic method from the melt are transported using a high-speed gas stream and placed on the collection surface to form a web of randomly distributed fibers obtained by the aerodynamic method. Alternatively, the carded web may be formed from a polymer by transporting fiber bundles obtained from the thermoplastic composition into a bobbin machine in which the fibers are separated. Then the fibers are passed through a carding or carding unit, in which additional separation and alignment of the fibers in the machine (longitudinal) direction is carried out with the formation of a fibrous non-woven fabric oriented in the machine direction. After molding, the non-woven fabric is usually stabilized using one or more known bonding techniques.

If necessary, the nonwoven fabric can also be a composite material containing a combination of fibers from a thermoplastic composition and fibers of other types (for example, staple fibers, threads, etc.). For example, additional synthetic fiber can be introduced, for example, fibers obtained from polyolefins, for example, polyethylene, polypropylene, polybutylene, etc .; polytetrafluoroethylene; polyesters, for example, polyethylene terephthalate, etc .; polyvinyl acetate; polyvinyl chloride acetate; polyvinyl butyral; acrylic polymers, for example polyacrylate, polymethyl acrylate, polymethyl methacrylate, etc .; polyamides, for example, nylon; polyvinyl chloride; polyvinylidene chloride; polystyrene; polyvinyl alcohol; polyurethanes; polylactic acid; etc. If necessary, biodegradable polymers can also be used, for example, polyglycolic acid (eng. Poly (glycolic acid), abbreviated PGA), polylactic acid (eng. Poly (lactic acid), abbreviated PLA), poly-β-malic acid (eng. poly (β-malic acid), abbreviated PMLA), poly-ε-caprolactone (English poly (ε-caprolactone), abbreviated PCL), poly-ρ-dioxanone (English poly (ρ-dioxanone), abbreviated PDS), polybutylene succinate (eng. poly (butylene succinate), abbreviated PBS) and poly-3-hydroxybutyrate (eng. poly (3-hydroxybutyrate), abbreviated as RNB). Some examples of known synthetic fibers include a sheath-core bicomponent fiber sold by KoSa Inc., Charlotte, North Carolina, under the names T-255 and T-256, where both products include a polyolefin sheath, or T-254, whose sheath consists of a low melting point ester copolymer. Other known bicomponent fibers may also be used, which include fibers available from Chisso Corporation, Moriyama, Japan, or Fibervisions LLC, Wilmington, Delaware. Staple fibers made from polylactic acid can also be used, for example, fibers supplied by Far Eastern Textile, Ltd., Taiwan.

The composite material may also contain cellulose fibers, for example, long and medium length cellulose fibers, short and medium length cellulose fibers, or mixtures thereof. One example of suitable fluffy cellulosic fibers of large and medium lengths includes softwood kraft pulp fibers. Softwood kraft pulp fibers are obtained from coniferous trees, non-limiting examples of which include softwood pulp fibers from northern, western and southern regions, which includes mahogany (common pine), Virginian juniper, Canadian spruce, Douglas fir, ordinary spruce , pine (e.g., southern pine), American spruce (e.g., black spruce), bamboo, combinations thereof, etc. For the implementation of the present invention can be used fiber from kraft pulp obtained from soft wood of trees of northern species. One example of commercially available kraft pulp fibers derived from southern tree softwood suitable for use in the present invention includes products sold under the trade name "NF-405" by Weyerhaeuser Company, with offices in Federal Way, Washington . Another example of cellulose suitable for use in accordance with the present invention is bleached sulfate cellulose, mainly containing softwood fibers, supplied by Bowater Corp., with offices in Greenville, SC, under the trade name CoosAbsorb S. According to the present invention also can be applied fibers of small and medium length. One example of suitable short and medium length cellulosic fibers is Kraft pulp fibers obtained from hardwood. Kraft cellulose fibers obtained from hardwood are obtained from deciduous trees, and they include cellulose fibers obtained from tree species, non-limiting examples of which include eucalyptus, maple, birch, aspen, etc. To increase softness, increase brightness, increase opacity and change the porosity of the fabric structure in order to increase its ability to capillary absorption, fibers from eucalyptus kraft cellulose are particularly preferred. Bamboo or cotton fibers may also be used.

Non-woven composite materials can be obtained using a variety of known methods. For example, the nonwoven composite material may be a "coform material" that contains a mixture or stabilized matrix of fibers from a thermoplastic composition and an absorbent material. For example, coform materials can be obtained by a process in which at least one extrusion die for producing fibers is melt-blown aerodynamically from a pipeline through which absorbent materials are added to the web during molding. Non-limiting examples of such absorbent materials may include cellulosic fibers, superabsorbent particles, inorganic and / or organic absorbent materials, processed polymer staple fiber, etc. The relative percentage of absorbent material can fluctuate over a wide range depending on the required characteristics of the nonwoven composite material. For example, the nonwoven composite material may contain from about 1 wt.% To about 60 wt.%, In some embodiments, from 5 wt.% To about 50 wt.%, And in some embodiments, from about 10 wt.% To about 40 wt.% fibers from a thermoplastic composition. Similarly, the nonwoven composite material may contain from about 40 wt.% To about 99 wt.%, In some embodiments, from 50 wt.% To about 95 wt.%, And in some embodiments, from about 60 wt.% To about 90 wt.% absorbing material. Some examples of such coform materials are described in US Pat. No. 4,100,324 to Anderson. et al .; US 5,284,703, Everhart, et al. and US 5350624, Georger, et al., the contents of which are fully incorporated into this description by reference for any purpose.

The present invention also includes the production of nonwoven multilayer materials in which one or more layers are obtained from a thermoplastic composition. For example, a nonwoven fabric comprising one layer may be a spunbond fabric containing a thermoplastic composition, and a nonwoven fabric comprising another layer may comprise a thermoplastic composition, another biodegradable polymer (s) and / or any other polymer (e.g., polyolefin). In one embodiment, the nonwoven laminate comprises an aerodynamic layer located between two spunbond layers to form a spunbond layer / aerodynamic layer / spunbond layer (English spunbond / meltblown / spunbond, abbreviated SMS "). If necessary, the spanbond layer (s) may be formed from a thermoplastic composition. The layer obtained by the aerodynamic method can be formed from a thermoplastic composition, another biodegradable polymer (s) and / or any other polymer (for example, a polyolefin). Various methods for producing multilayer materials such as SMS are described in patents US 4041203, Brock et al .: US 5213881, Timmons. et al .: US 5464688, Timmons. et al .; US 4374888, Bornslaeger: US 5169706, Collier, et al .; and US 4766029, Brock et al., as well as in published patent application US No. 2004/0002273, Fitting, et al., the contents of which are fully incorporated into this description by reference for any purpose. Of course, the nonwoven multilayer material may have a different configuration and include any desired number of layers obtained by the aerodynamic method and obtained by high-speed molding, for example, be a multilayer material comprising: a spunbond layer / aerodynamically obtained layer / aerodynamically obtained layer / spunbond layer (type "SMMS"), or be a multilayer material, including: a spunbond layer / layer obtained by an aerodynamic method (type "SM"), etc. Although the density values of the nonwoven laminate can be tailored specifically for a particular application, these values typically range from about 10 to about 300 grams per square meter ("g / sq."), In some embodiments, from about 25 up to about 200 g / m2, and in some embodiments, from about 40 to about 150 g / m2.

If necessary, in order to impart the required characteristics to the nonwoven fabric or the multilayer material, the nonwoven fabric or the multilayer material can be subjected to various processing. For example, the web may be treated with anti-wetting agents, antistatic agents, surfactants, coloring agents, anti-fog agents, fluorinated chemicals that repel blood or alcohol, lubricants and / or antimicrobial agents. In addition, to increase the filtering efficiency, the web can be subjected to electret processing, which gives the material an electrostatic charge. The charge distribution may include layers of positive or negative charges located on or near the surface of the polymer, or charge clouds located in the mass of the polymer. The charge may also include polarization charges “frozen” in the ordered arrangement of molecular dipoles. Techniques for electret treatment of tissue are well known to specialists in this field of technology. Non-limiting examples of such techniques include heat treatment, contact with a liquid, electron beam irradiation, and corona discharge. In one specific embodiment, the electret treatment is a corona discharge that includes exposing a laminate to a pair of electric fields having opposite polarities. Other methods for producing electret materials are described in US Pat. No. 4,215,668 to Kubik. et al .; US 4,375,718; Wadsworth: US 4,592,815; Nakao; US 4,874,659, Ando; US 5401446, Tsai, et al .; US 5883026, Reader, et al .; US 5908598, Rousseau, et al .; US 6365,088, Knight, et al., The contents of which are fully incorporated into this description by reference for any purpose.

IV. Products

Non-woven fabric can have many uses. For example, a sheet can be inserted into a “medical device”, for example, a dressing gown, surgical sheets, protective masks, hats, surgical hats, shoe covers, sterilization wraps, heated blankets, heating mats (mattresses), etc. Of course, the nonwoven fabric could also be used for the manufacture of various other products. For example, a nonwoven web may be incorporated into an “absorbent article” that can absorb water or other fluids. Non-limiting examples of some absorbent articles include absorbent articles for personal use, for example, diapers (diapers), sweatpants, absorbent underpants, incontinence products, feminine hygiene products (eg, sanitary napkins), bathing suits, sanitary napkins for babies, hygienic hand wipes, etc .; medical absorbent products, for example, clothing, materials to limit the surgical field, underwear, mattress covers, dressings, absorbent sheets and medical napkins; food wipes; clothes handbags etc. Materials and methods suitable for the manufacture of such products are well known to those skilled in the art. For example, absorbent articles typically include a layer substantially impervious to liquid (e.g., an outer shell), a layer permeable to liquid (e.g., a layer adjacent to the body, a layer located on the side of the fluid flow, etc.) and an absorbent the inner layer. For example, in one embodiment, the nonwoven fabric obtained according to the present invention can be used to obtain the outer shell of an absorbent article. If necessary, the nonwoven fabric can be attached to a liquid impermeable film, which can be either permeable or vapor impermeable.

A better understanding of the present invention can be achieved after reading the examples below. In each of the examples below, prior to mixing with the polyepoxide modifier, polylactic acid was dried in a desiccator at a temperature of approximately 77 ° C. Before fiber production, the resulting mixture was also dried in a desiccator at a temperature of 125 ° F to 150 ° F (approximately 51.67 ° C to 65.56 ° C). Example 1

A control fiber of 100% polylactic acid (PMA) was obtained by extruding PLA 6201 D (Natureworks®, melt flow rate of 10 g / 10 min at 190 ° C.) as a fiber. In particular, polylactic acid was fed to an extruder heated to a temperature of 235 ° C. The extruder productivity was 0.4 grams per hole per minute (using a spinneret kit having 16 holes per inch). The melt was extruded through a spinneret assembly, producing continuous fibers, which were then rapidly cooled by air at a temperature of 25 ° C, driven by a blower. Then, the continuous fibers were pulled through the fiber stretcher and sent to the spinning disk at a speed of 2000 meters per minute ("m / min"). The obtained degree of elongation was 1549. The fibers were collected at a speed of 2000 m / min, obtaining the target fiber with a thickness of 15 μm. Then the fibers were transported to a spinning disk at a speed of 3000 meters per minute ("m / min"). The obtained degree of traction was 2324.

Example 2

The ability to form fibers, including 97 wt.% Polylactic acid (PLA 6201 D, Natureworks®) and 3 wt.% Polyepoxide modifier, was investigated. The polyepoxide modifier was a triple copolymer of ethylene, methyl acrylate and glycidyl methacrylate (Sigma-Aldrich Co.), having a melt flow rate of 6 g / 10 min (190 ° C / 2160 g), a glycidyl methacrylate content of 8 wt.%, Methyl acrylate content - 25 wt.% And ethylene content - 67 wt.% The polymers were fed into a twin screw extruder Thermo Prism ™ USALAB 16 (Thermo Electron Corp., Stone, England). The melt temperature in the extruder was 195 ° C. The extruder included 11 zones, respectively numbered 0-10, ranging from the feed hopper to the extrusion head. The polymer containing polylactic acid was mixed dry with the polyepoxide modifier and sent to the feed hole of the extruder (not heated, located up to zone 1 of the extruder) at a speed of 3 pounds per hour (approximately 1.36 kg per hour). The screw speed was 200 rpm. The extrusion head used for extrusion of the polymer had 1 hole (3 mm in diameter). After molding, the extruded polymer was cooled on a belt conveyor cooled by a blower and formed into granules. Then the granules were sent to an extruder, heated to a temperature of 240 ° C. The extruder productivity was 0.4 grams per hole per minute (using a spinneret kit having 16 holes per inch). The melt was extruded through a spinneret assembly, producing continuous fibers, which were then rapidly cooled by air at a temperature of 25 ° C, driven by a blower. Then, the continuous fibers were pulled onto a spinning disk at a speed of 2000 meters per minute. The obtained degree of traction was 1549.

Example 3

The fibers were obtained from a mixture comprising 95 wt.% Polylactic acid (PLA 6201 D, Natureworks®) and 5 wt.% Ternary copolymer of ethylene, methyl acrylate and glycidyl methacrylate (Sigma-Aldrich Co.), as described in Example 2. Then, continuous fibers pulled onto a spinning disk at a speed of 2000 meters per minute. The obtained stretch ratio was 1549. The fibers were also twisted at a speed of 3000 meters per minute, obtaining a stretch ratio of 2324.

Example 4

The fibers were obtained from a mixture comprising 90 wt.% Polylactic acid (PLA 6201 D, Natureworks®) and 10 wt.% Ternary copolymer of ethylene, methyl acrylate and glycidyl methacrylate (Sigma-Aldrich Co.), as described in Example 2, except that the fibers were extruded at 215 ° C and pulled onto a spinning disk at a speed of 500 m / min, obtaining a degree of elongation of 387. Before forming the fibers, the mixture was examined using transmission electron microscopy (TEM). The image of the mixture at a magnification of 10,000 is shown in FIG. As shown, the mixture contains many small domains, presented in the form of darker areas.

Example 5

Granules were obtained from a mixture containing 85 wt.% Polylactic acid (PLA 6201 D, Natureworks®) and 15 wt.% Ternary copolymer of ethylene, methyl acrylate and glycidyl methacrylate (Sigma-Aldrich Co.), as described in Example 2. From the obtained granules did not receive fiber.

Example 6

The fibers were obtained from a mixture comprising 90 wt.% Polylactic acid (PLA 6201 D, Natureworks®) and 10 wt.% Polyepoxide modifier. The polyepoxide modifier was a triple copolymer of ethylene, methyl acrylate and glycidyl methacrylate (Lotader® AX8950, Arkema), having a melt flow rate of 70-100 g / 10 min (190 ° C / 2160 g), a glycidyl methacrylate content of 7 to 11 masses %, a methyl acrylate content of 13 to 17% by mass, and an ethylene content of 72 to 80% by mass. The same recipe was used as in Example 2, except that the fibers were extruded at 210 ° C and pulled onto a spinning disk at a speed of 800 m / min, as a result what got the degree of extension of 620.

Example 7

Granules were obtained from a mixture containing 90 wt.% Polylactic acid (PLA 6201 D, Natureworks®) and 10 wt.% Ternary copolymer of ethylene, methyl acrylate and glycidyl methacrylate (Sigma-Aldrich Co.), as described in Example 2, except that the polymers were mixed with each other at a melt temperature of 235 ° C. No fibers were obtained from the obtained granules.

According to the excerpts of Examples 1-4 and 6, ten (10) samples were obtained, for which tensile and elongation strengths were then determined. The results (averaged) are presented below.

Table 1 Properties of the fibers obtained in examples 1-4 and 6 Example # PMK (wt.%) Epoxy Functionalized Modifier Diameter (μm) Elongation (%) Tensile strength (g / g) Moisture content before spinning (parts per million (ppm)) Melt Flow Index (g / 10 min) mass%

one one hundred - 0 10.31 43.01 4.17 40 2 97 6 3 14.84 123.40 2.19 73 3 95 6 5 14.89 147.13 1.74 59 four 90 6 10 25.54 32.07 1,60 47 6 90 -70-100 10 21.09 41.93 1.93 53

Example 8

The ability of the mixture to form fibers, including 88.7 wt.% Polylactic acid (PLA 6201 D, Natureworks®), 1.5 wt.% Polyepoxide modifier and 9.8 wt.% Hardening additive, was investigated. The polyepoxide modifier was a triple copolymer of ethylene, methyl acrylate and glycidyl methacrylate (Lotader® AX8950, Arkema). The strengthening additive was Vistamaxx ™ 2120 (Exxonmobil), which is a polyolefin copolymer / elastomer having a melt flow rate of 29 g / 10 min (190 ° C, 2160 g) and a density of 0.866 g / cm ³ . The polymers were sent to an extruder with two screws rotating in the same direction (ZSK-30, 30 mm in diameter, 1328 mm long) used for compounding, which was supplied by Werner and Pfleiderer Corporation, Ramsey, New Jersey. The extruder included 14 zones, respectively numbered 1-14, starting from the feed hopper to the extrusion head. The polymers were sent to first cylinder # 1 through a gravity feeder at a total flow rate of 15 pounds per hour (6.8 kg per hour). The extrusion head used for extrusion of the polymer had 3 die holes (with a diameter of 6 millimeters), the distance between which was 4 millimeters. After molding, the extruded polymer was cooled on an air-cooled belt conveyor and formed into pellets using a Conair granulator. The screw speed was 100 rpm. Then the granules were sent to an extruder, heated to a temperature of 220 ° C. The extruder productivity was 0.4 grams per hole per minute (using a spinneret kit having 16 holes per inch). The melt was extruded through a spinneret assembly, producing continuous fibers, which were then rapidly cooled by air at a temperature of 25 ° C, driven by a blower. Then, the continuous fibers were pulled onto a spinning disk at a speed of 1000 meters per minute. The obtained degree of traction was 775.

Example 9

Fibers were obtained as described in Example 8, except that the temperature at which the fibers were extruded was 240 ° C, and the spin speed of the spinning disk was 1000 meters per minute. The obtained degree of traction was 775.

Example 10

Fibers were obtained as described in Example 8, except that the reinforcing additive was Escorene ™ Ultra 7720 (Exxonmobil), which is an ethylene vinyl acetate ("EVA") polymer that has a melt flow rate of 150 g / 10 min and density 0.946 g / cm ^3, when the traction drive of the spinning speed is 700 meters per minute. The resulting degree of traction was 542.

Example 11

Fibers were obtained as described in Example 10, except that the temperature at which the fibers were extruded was 240 ° C and the spinning speed of the spinning disk was 1000 meters per minute. The obtained degree of traction was 775.

Example 12

Fibers were obtained as described in Example 10, except that the temperature at which the fibers were extruded was 230 ° C.

Example 13

Fibers were obtained as described in Example 8, except that the temperature at which the polymers were mixed was 235 ° C, the temperature at which the fibers were extruded was 235 ° C, and the spin speed of the spinning disk was 3000 meters per minute . The obtained degree of traction was 2324.

According to the copybooks of Examples 8-13, ten (10) samples were obtained, for which tensile and elongation strengths were then determined. The results (averaged) are presented below.

Table 2 The properties of the fibers obtained in examples 8-13

Etc. # Hardening additive Pace. mixing (° C) Pace. fiber extrusion (° C) Diameter (μm) Elongation (%) Tensile strength g / g Moisture content before spinning (parts per million) 8 Vistamaxx ™ 2120 185 220 17.21 60.91 1.92 195 9 Vistamaxx ™ 2120 185 240 20.59 119.80 2.03 195 10 Escorene ™ 185 220 25.49 89.47 2.20 85

Ultra 7720 eleven Escorene ™ Ultra 7720 185 240 17.25 65.93 2.00 85 12 Escorene ™ Ultra 7720 185 230 19.17 96.01 1.97 85 13 Vistamaxx ™ 2120 235 235 12.85 83.87 1.99 57

Example 14

The ability of the mixture to form fibers, including 89.6 wt.% Polylactic acid (PLA 6201 D, Natureworks®), 0.5 wt.% Polyepoxide modifier and 9.9 wt.% Hardening additive, was investigated. The polyepoxide modifier was a triple copolymer of ethylene, methyl acrylate and glycidyl methacrylate (Lotader® AX8950, Arkema). The reinforcing additive was Vistamaxx ™ 2120 (Exxonmobil). The polymers were sent to an extruder with two screws rotating in the same direction (ZSK-30, 30 mm in diameter, 1328 mm long) used for compounding, which was supplied by Werner and Pfleiderer Corporation, Ramsey, New Jersey. The extruder included 14 zones, respectively numbered 1-14, starting from the feed hopper to the extrusion head. The polymers were sent to first cylinder # 1 through a gravity feeder at a total flow rate of 15 pounds per hour (6.8 kg per hour). The extrusion head used for extrusion of the polymer had 3 die holes (with a diameter of 6 millimeters), the distance between which was 4 millimeters. After molding, the extruded polymer was cooled on an air-cooled belt conveyor and formed into pellets using a Conair granulator. The screw speed was 100 rpm. Then the granules were sent to an extruder, heated to a temperature of 220 ° C. The extruder productivity was 0.4 grams per hole per minute (using a spinneret kit having 16 holes per inch). The melt was extruded through a spinneret assembly, producing continuous fibers, which were then rapidly cooled by air at a temperature of 25 ° C, driven by a blower. Then, the continuous fibers were pulled onto a spinning disk at a speed of 500 meters per minute. The obtained degree of traction was 387. The collection of fibers was impossible.

Example 15

Fibers were obtained as described in Example 14, except that the temperature at which the fibers were extruded was 225 ° C and the spinning disk speed was 750 m / min. Fiber collection was not possible.

Example 16

Fibers were obtained as described in Example 14, except that the temperature at which the fibers were extruded was 230 ° C and the spinning disk speed was 1500 m / min. Fiber collection was not possible.

Example 17

Fibers were obtained as described in Example 14, except that the temperature at which the fibers were extruded was 235 ° C and the spinning disk speed was 2000 m / min. The fibers were collected at 2000 m / min, and the spinning of the fibers was carried out at a speed of 3000 m / min.

Example 18

Fibers were obtained as described in Example 14, except that the temperature at which the fibers were extruded was 240 ° C and the spinning disk speed was 2000 m / min. The fibers were collected at 2000 m / min, and the spinning of the fibers was carried out at a speed of 3000 m / min.

Example 19

Fibers were obtained as described in Example 14, except that the temperature at which the fibers were extruded was 245 ° C and the spinning disk speed was 2000 m / min. The fibers were collected at 2000 m / min, and the spinning of the fibers was carried out at a speed of 2800 m / min.

Example 20

Fibers were obtained as described in Example 14, except that the temperature at which the fibers were extruded was 250 ° C and the spinning disk speed was 2000 m / min. The fibers were collected at 2000 m / min, and the spinning of the fibers was carried out at a speed of 2900 m / min.

According to the excerpts of Examples 17-20, ten (10) samples were obtained for which tensile and elongation strengths were then determined. The results (averaged) are presented below.

Table 3 The properties of the fibers obtained in examples 17-20 Example # Pace. fiber extrusion (° C) Spinning Disc Speed (m / min) Diameter (μm) Elongation (%) Tensile strength g / g Max. degree of traction Moisture content before spinning (parts per million) 17 235 ° C 2000 15.0 60.6 1.8 2324 133 eighteen 240 ° C 2000 14.7 94.0 2,3 2324 133

19 245 ° C 2000 14.6 95.6 2.2 2169 133 twenty 250 ° C 2000 15,2 101,2 1.7 2246 133

Example 21

The ability of the mixture to form fibers, including 88.7 wt.% Polylactic acid (PLA 6201 D, Natureworks®), 1.5 wt.% Polyepoxide modifier and 9.8 wt.% Hardening additive, was investigated. The polyepoxide modifier was a triple copolymer of ethylene, methyl acrylate and glycidyl methacrylate (Lotader® AX8950, Arkema). The reinforcing additive was Vistamaxx ™ 2120 (Exxonmobil). The polymers were sent to an extruder with two screws rotating in the same direction (ZSK-30, 30 mm in diameter, 1328 mm long) used for compounding, which was supplied by Werner and Pfleiderer Corporation, Ramsey, New Jersey. The extruder included 14 zones, respectively numbered 1-14, starting from the feed hopper to the extrusion head. The polymers were sent to first cylinder # 1 through a gravity feeder at a total flow rate of 15 pounds per hour (6.8 kg per hour). The extrusion head used for extrusion of the polymer had 3 die holes (with a diameter of 6 millimeters), the distance between which was 4 millimeters. After molding, the extruded polymer was cooled on an air-cooled belt conveyor and formed into pellets using a Conair granulator. The screw speed was 100 rpm. Then the granules were sent to an extruder, heated to a temperature of 220 ° C. The extruder productivity was 0.4 grams per hole per minute (using a spinneret kit having 16 holes per inch). The melt was extruded through a spinneret assembly, producing continuous fibers, which were then rapidly cooled by air at a temperature of 25 ° C, driven by a blower. Then, the continuous fibers were pulled onto a spinning disk at a speed of 500 meters per minute. The obtained degree of traction was 387. The collection of fibers was impossible.

Example 22

Fibers were obtained as described in Example 21, except that the temperature at which the fibers were extruded was 225 ° C and the spinning disk speed was 1200 m / min. Fiber collection was not possible.

Example 23

Fibers were obtained as described in Example 21, except that the temperature at which the fibers were extruded was 230 ° C and the spinning disk speed was 2000 m / min. The fibers were collected at 2000 m / min, and the spinning of the fibers was carried out at a speed of 2400 m / min.

Example 24

Fibers were obtained as described in Example 21, except that the temperature at which the fibers were extruded was 235 ° C and the spinning disk speed was 2000 m / min. The fibers were collected at 2000 m / min, and the spinning of the fibers was carried out at a speed of 3000 m / min.

Example 25

Fibers were obtained as described in Example 21, except that the temperature at which the fibers were extruded was 240 ° C and the spinning disk speed was 2000 m / min. The fibers were collected at 2000 m / min, and the spinning of the fibers was carried out at a speed of 3000 m / min.

Example 26

Fibers were obtained as described in Example 21, except that the temperature at which the fibers were extruded was 245 ° C and the spinning disk speed was 2000 m / min. The fibers were collected at 2000 m / min, and the spinning of the fibers was carried out at a speed of 3000 m / min.

Example 27

Fibers were obtained as described in Example 21, except that the temperature at which the fibers were extruded was 250 ° C and the spinning disk speed was 2000 m / min. The fibers were collected at 2000 m / min, and the spinning of the fibers was carried out at a speed of 2800 m / min.

According to the excerpts of Examples 23-27, ten (10) samples were obtained, for which tensile and elongation strengths were then determined. The results (averaged) are presented below.

Table 4 The properties of the fibers obtained in examples 23-27 Example # Pace. fiber extrusion (° C) Spinning Disc Speed (m / min) Diameter (μm) Elongation (%) Tensile strength g / g Max. degree of traction Moisture content before spinning (parts per million) 23 230 ° C 2000 14.7 48.5 1.7 1859 306 24 235 ° C 2000 15.0 64,2 1,6 2324 306 25 240 ° C 2000 15.0 103.1 1.9 2324 306 26 245 ° C 2000 14.7 105,2 1.9 2324 306 27 250 ° C 2000 14.7 101.3 1,6 2169 306

Example 28

The ability of the mixture to form fibers, including 87.8 wt.% Polylactic acid (PLA 6201 D, Natureworks®), 2.4 wt.% Polyepoxide modifier and 9.8 wt.% Hardening additive, was investigated. The polyepoxide modifier was a triple copolymer of ethylene, methyl acrylate and glycidyl methacrylate (Lotader® AX8950, Arkema). The reinforcing additive was Vistamaxx ™ 2120 (Exxonmobil). The polymers were sent to an extruder with two screws rotating in the same direction (ZSK-30, 30 mm in diameter, 1328 mm long) used for compounding, which was supplied by Werner and Pfleiderer Corporation, Ramsey, New Jersey. The extruder included 14 zones, respectively numbered 1-14, starting from the feed hopper to the extrusion head. The polymers were sent to first cylinder # 1 through a gravity feeder at a total flow rate of 15 pounds per hour (6.8 kg per hour). The extrusion head used for extrusion of the polymer had 3 die holes (with a diameter of 6 millimeters), the distance between which was 4 millimeters. After molding, the extruded polymer was cooled on an air-cooled belt conveyor and formed into pellets using a Conair granulator. The screw speed was 100 rpm. Then the granules were sent to an extruder, heated to a temperature of 220 ° C. The extruder productivity was 0.4 grams per hole per minute (using a spinneret kit having 16 holes per inch). The melt was extruded through a spinneret assembly, producing continuous fibers, which were then rapidly cooled by air at a temperature of 25 ° C, driven by a blower. Then, the continuous fibers were pulled onto a spinning disk at a speed of 1300 meters per minute. The obtained degree of traction was 387. The collection of fibers was impossible.

Example 29

Fibers were obtained as described in Example 28, except that the temperature at which the fibers were extruded was 225 ° C and the spinning disk speed was 1500 m / min. Fiber collection was not possible.

Example 30

Fibers were obtained as described in Example 28, except that the temperature at which the fibers were extruded was 230 ° C and the spinning disk speed was 2000 m / min. The fibers were collected at 2000 m / min, and the spinning of the fibers was carried out at a speed of 3000 m / min.

Example 31

Fibers were obtained as described in Example 28, except that the temperature at which the fibers were extruded was 235 ° and the spinning disk speed was 2000 m / min. The fibers were collected at 2000 m / min, and the spinning of the fibers was carried out at a speed of 2900 m / min.

Example 32

Fibers were obtained as described in Example 28, except that the temperature at which the fibers were extruded was 240 ° C and the spinning disk speed was 2000 m / min. The fibers were collected at 2000 m / min, and the spinning of the fibers was carried out at a speed of 3000 m / min.

Example 33

Fibers were obtained as described in Example 28, except that the temperature at which the fibers were extruded was 245 ° C and the spinning disk speed was 2000 m / min. The fibers were collected at 2000 m / min, and the spinning of the fibers was carried out at a speed of 3000 m / min.

Example 34

Fibers were obtained as described in Example 28, except that the temperature at which the fibers were extruded was 250 ° C and the spinning disk speed was 2000 m / min. The fibers were collected at 2000 m / min, and the spinning of the fibers was carried out at a speed of 2800 m / min.

According to the copybooks of Examples 30-34, ten (10) samples were obtained for which tensile and elongation strengths were then determined. The results (averaged) are presented below.

Table 5 Properties of the fibers obtained in examples 30-34 Example # Pace. fiber extrusion (° C) Spinning Disc Speed (m / min) Diameter (μm) Elongation (%) Tensile strength g / g Max. degree of traction Moisture content before spinning (parts per million) thirty 230 ° C 2000 14.5 45.9 1,6 2324 297 31 235 ° C 2000 14.6 70.7 1,6 2246 297 32 240 ° C 2000 13.8 86.8 1.9 2324 297 33 245 ° C 2000 14.2 105.5 1.9 2324 297 34 250 ° C 2000 14.6 95.1 1,6 2169 297

Example 35

The ability of the mixture to form fibers, including 88.7 wt.% Polylactic acid (PLA 6201 D, Natureworks®), 1.5 wt.% Polyepoxide modifier and 9.8 wt.% Hardening additive, was investigated. The polyepoxide modifier was a triple copolymer of ethylene, methyl acrylate and glycidyl methacrylate (Lotader® AX8950, Arkema). The reinforcing additive was Vistamaxx ™ 2120 (Exxonmobil). The polymers were sent to an extruder with two screws rotating in the same direction (ZSK-30, 30 mm in diameter, 1328 mm long) used for compounding, supplied by Wemer and Pfleiderer Corporation, Ramsey, New Jersey. The extruder included 14 zones, respectively numbered 1-14, starting from the feed hopper to the extrusion head. The polymers were sent to first cylinder # 1 through a gravity feeder at a total flow rate of 15 pounds per hour (6.8 kg per hour). The extrusion head used for extrusion of the polymer had 3 die holes (with a diameter of 6 millimeters), the distance between which was 4 millimeters. After molding, the extruded polymer was cooled on an air-cooled belt conveyor and formed into pellets using a Conair granulator. The screw speed was 200 rpm. Then the granules were sent to an extruder, heated to a temperature of 220 ° C. The extruder productivity was 0.4 grams per hole per minute (using a spinneret kit having 16 holes per inch). The melt was extruded through a spinneret assembly, producing continuous fibers, which were then rapidly cooled by air at a temperature of 25 ° C, driven by a blower. Then, the continuous fibers were pulled onto a spinning disk at a speed of 2000 meters per minute. The obtained degree of traction was 1547. The fibers were collected, and then the spinning disk speed was increased to 3000 m / min.

Example 36

Fibers were obtained as described in Example 35, except that the temperature at which the fibers were extruded was 230 ° C and the spinning disk speed was 2000 m / min. The fibers were collected at 2000 m / min, and the spinning of the fibers was carried out at a speed of 3000 m / min.

Example 37

Fibers were obtained as described in Example 35, except that the temperature at which the fibers were extruded was 235 ° C and the spinning disk speed was 2000 m / min. The fibers were collected at 2000 m / min, and the spinning of the fibers was carried out at a speed of 3000 m / min.

Example 38

Fibers were obtained as described in Example 35, except that the temperature at which the fibers were extruded was 240 ° C and the spinning disk speed was 2000 m / min. The fibers were collected at 2000 m / min, and the spinning of the fibers was carried out at a speed of 3000 m / min.

Example 39

Fibers were obtained as described in Example 35, except that the temperature at which the fibers were extruded was 245 ° C and the spinning disk speed was 2000 m / min.

Example 40

Fibers were obtained as described in Example 35, except that the temperature at which the fibers were extruded was 250 ° C and the spinning disk speed was 2000 m / min. The fibers were collected at 2000 m / min, and the spinning of the fibers was carried out at a speed of 3000 m / min.

Example 41

Fibers were obtained as described in Example 35, except that the temperature at which the fibers were extruded was 255 ° and the spinning disk speed was 2000 m / min. The fibers were collected at 2000 m / min, and the spinning of the fibers was carried out at a speed of 3000 m / min.

According to the excerpts of Examples 35-41, ten (10) samples were obtained for which tensile and elongation strengths were then determined. The results (averaged) are presented below.

Table 6 Properties of the fibers obtained in examples 35-41 Example # Pace. fiber extrusion (° C) Spinning Disc Speed (m / min) Diameter (μm) Elongation (%) Tensile strength g / g Max. degree of traction Moisture content before spinning (parts per million) 35 220 ° C 2000 13.85 59.14 1.48 2324 629 36 230 ° C 2000 14.02 81.77 1,50 2324 629 37 235 ° C 2000 14.45 93.85 1,62 2324 473 38 240 ° C 2000 14.75 121.63 1.79 2324 473 39 245 ° C 2000 14.60 125.88 1.94 2324 473 40 250 ° C 2000 14.53 127.68 1.85 2324 217 41 255 ° C 2000 14.70 123.97 1.79 2324 217

Example 42

Also investigated were fibers obtained from a mixture containing 88.7% by weight of polylactic acid (PLA 6201 D, Natureworks®), 9.8% by weight of a reinforcing additive, and 1.5% by weight of a polyepoxide modifier. The polyepoxide modifier was a triple copolymer of ethylene, methyl acrylate and glycidyl methacrylate (Lotader® AX8950, Arkema). The reinforcing additive was PP 3155 (Exxonmobil), a polypropylene homopolymer. The polymers were sent to an extruder with two screws rotating in the same direction (ZSK-30, 30 mm in diameter, 1328 mm long) used for compounding, which was supplied by Werner and Pfleiderer Corporation, Ramsey, New Jersey. The extruder included 14 zones, respectively numbered 1-14, starting from the feed hopper to the extrusion head. The polymers were sent to first cylinder # 1 through a gravity feeder at a total flow rate of 15 pounds per hour (6.8 kg per hour). The extrusion head used for extrusion of the polymer had 3 die holes (with a diameter of 6 millimeters), the distance between which was 4 millimeters. After molding, the extruded polymer was cooled on an air-cooled belt conveyor and formed into pellets using a Conair granulator. The screw speed was 100 rpm. Then the granules were sent to an extruder, heated to a temperature of 230 ° C. The extruder productivity was 0.4 grams per hole per minute (using a spinneret kit having 16 holes per inch). The melt was extruded through a spinneret assembly, producing continuous fibers, which were then rapidly cooled by air at a temperature of 25 ° C, driven by a blower. Then, the continuous fibers were pulled onto a spinning disk at a speed of 2000 meters per minute. The fibers were collected at 2000 m / min, and the spinning of the fibers was carried out at a speed of 3000 m / min.

Example 43

Fibers were obtained as described in Example 42, except that the temperature at which the fibers were extruded was 235 ° C and the spinning disk speed was 2000 m / min. The fibers were collected at 2000 m / min, and the spinning of the fibers was carried out at a speed of 3000 m / min.

Example 44

Fibers were obtained as described in Example 42, except that the temperature at which the fibers were extruded was 240 ° C and the spinning disk speed was 2000 m / min. The fibers were collected at 2000 m / min, and the spinning of the fibers was carried out at a speed of 3000 m / min.

According to the excerpts of Examples 42-44, ten (10) samples were obtained, for which tensile and elongation strengths were then determined. The results (averaged) are presented below.

Table 7 The properties of the fibers obtained in examples 42-44 Etc. # Epoxy functionalized modifier (wt.%) Pace. fiber extrusion (° C) Spinning Disc Speed (m / min) Diameter (μm) Elongation (%) Tensile strength g / g Max. degree of traction Moisture content before spinning (parts per million) 42 1,5 230 ° C 2000 12.80 87.52 2.88 2324 630 43 1,5 235 ° C 2000 12.90 87.65 2.86 2324 630 44 1,5 240 ° C 2000 12.24 88.76 2.98 2324 630

Example 45 The ability of a mixture to form fibers, including 89.25 wt.% Polylactic acid (PLA 6201 D, Natureworks®), 0.75 wt.% Polyepoxide modifier and 10 wt.% Hardening additive, was investigated. The polyepoxide modifier was a triple copolymer of ethylene, methyl acrylate and glycidyl methacrylate (Lotader® AX8900, Arkema). The reinforcing additive was PP 3155 (Exxon-Mobil), a polypropylene homopolymer. The polymers were sent to an extruder with two screws rotating in the same direction (ZSK-30, 30 mm in diameter, 1328 mm long) used for compounding, which was supplied by Werner and Pfleiderer Corporation, Ramsey, New Jersey. The extruder included 14 zones, respectively numbered 1-14, starting from the feed hopper to the extrusion head. The polymers were sent to first cylinder # 1 through a gravity feeder at a total flow rate of 15 pounds per hour (6.8 kg per hour). The extrusion head used for extrusion of the polymer had 3 die holes (with a diameter of 6 millimeters), the distance between which was 4 millimeters. After molding, the extruded polymer was cooled on an air-cooled belt conveyor and formed into pellets using a Conair granulator. The screw speed was 200 rpm. After molding, the extruded polymer was cooled on a belt conveyor cooled by a blower and formed into granules. Then the granules were sent to an extruder, heated to a temperature of 240 ° C. The extruder productivity was 0.4 grams per hole per minute (using a spinneret kit having 16 holes per inch). The melt was extruded through a spinneret assembly, producing continuous fibers, which were then rapidly cooled by air at a temperature of 25 ° C, driven by a blower. Then, the continuous fibers were pulled onto a spinning disk at a speed of 2000 meters per minute. The obtained degree of traction was 1547. The fibers were collected, and then the spinning disk speed was increased to 3000 m / min. Then the performance of the extruder was reduced to 0.28 grams per hole per minute, and the fibers were pulled onto the spinning disk at a speed of 3000 m / min, resulting in a degree of traction of 3320.

Example 46

Fibers were obtained as described in Example 45, except that the temperature at which the fibers were extruded was 245 ° C and the spinning disk speed was 2000 m / min. Fibers were not collected.

Example 47

Fibers were obtained as described in Example 45, except that the temperature at which the fibers were extruded was 250 ° C and the spinning disk speed was 2000 m / min. Fibers were not collected.

Example 48

Fibers were obtained as described in Example 45, except that the concentration of Lotader ™ AX8900 was 0.5% and the spinning disk speed was 2000 m / min. The fibers were collected at 2000 m / min, and spinning was carried out at a speed of 3000 m / min and a productivity of 0.16 grams per hole per minute, resulting in a degree of elongation of 5810.

Example 49

Fibers were obtained as described in Example 45, except that the polypropylene concentration was 2.5% and the spinning disk speed was 2000 m / min. The fibers were collected at 2000 m / min, and spinning was carried out at a speed of 3000 m / min and a productivity of 0.24 grams per hole per minute, resulting in a degree of elongation of 3873. Before forming the fibers, the mixture was examined using transmission electron microscopy ( "TEM"). The image of the mixture at a magnification of 10,000 is shown in FIG. 3. As shown, the mixture contains many domains of Lotader® AX 8900, the size of which is on the order of nanometers, which are represented by small darker areas, as well as many domains formed by polypropylene, whose size is on the order of micrometers, which are represented by large, dark areas.

Example 50

Fibers were obtained as described in Example 45, except that the polyepoxide modifier was CESA ™ Extend 8478 (Clariant Corporation, 10% BASF Joncryl ™ ADR 4368, diluted in Natureworks PLA 6201 D) and the CESA concentration was 0.5 mass .%; the spinning disk speed was 2000 m / min, resulting in a degree of extension of 1549 was obtained. No fibers were collected.

Before forming the fibers, the mixture was examined using transmission electron microscopy ("TEM"). An image of the mixture at a magnification of 10,000 is shown in FIG. 4. As shown, the mixture contains many large domains, presented in the form of darker areas. According to the prescriptions of Examples 45, 48, and 49, ten (10) samples were obtained, for which tensile and elongation strengths were then determined. The results (averaged) are presented below.

Table 8 The properties of the fibers obtained in Examples 45 and 48-49 Example # Epoxy functionalized modifier (wt.%) Pace. fiber extrusion (° C) Spinning Disc Speed (m / min) Diameter (μm) Elongation (%) Tensile strength g / g Max. degree of traction Moisture content before spinning (parts per million) 45 0.75 240 ° C 2000 13,4 98.9 2.2 3320 83 48 0.50 240 ° C 2000 14.3 97.8 2,3 5810 43 49 0.75 240 ° C 2000 14.5 112.0 2.2 3873 332

Example 51 The ability of a mixture to form fibers comprising 98.5 wt.% Polylactic acid (PLA 6201 D, Natureworks®) and 1.5 wt.% Polyepoxide modifier was investigated. The polyepoxide modifier was a triple copolymer of ethylene, methyl acrylate and glycidyl methacrylate (Lotader® AX8900, Arkema). The polymers were sent to an extruder with two screws rotating in the same direction (ZSK-30, 30 mm in diameter, 1328 mm long) used for compounding, which was supplied by Werner and Pfleiderer Corporation, Ramsey, New Jersey. The extruder included 14 zones, respectively numbered 1-14, starting from the feed hopper to the extrusion head. The polymers were sent to first cylinder # 1 through a gravity feeder at a total flow rate of 15 pounds per hour (6.8 kg per hour). The extrusion head used for extrusion of the polymer had 3 die holes (with a diameter of 6 millimeters), the distance between which was 4 millimeters. After molding, the extruded polymer was cooled on an air-cooled belt conveyor and formed into pellets using a Conair granulator. The screw speed was 200 rpm. After molding, the extruded polymer was cooled on a belt conveyor cooled by a blower and formed into granules. Then the granules were sent to an extruder, heated to a temperature of 240 ° C. The extruder productivity was 0.4 grams per hole per minute (using a spinneret kit having 16 holes per inch). The melt was extruded through a spinneret assembly, producing continuous fibers, which were then rapidly cooled by air at a temperature of 25 ° C, driven by a blower. Then, the continuous fibers were pulled onto a spinning disk at a speed of 2000 meters per minute. The obtained degree of traction was 1547. No fibers were collected, but the spinning disk speed was increased to 3000 m / min. Then the performance of the extruder was reduced to 0.28 grams per hole per minute, and the fibers were pulled onto a spinning disk at 3000 m / min, resulting in a degree of traction of 3320.

Before forming the fibers, the mixture was examined using transmission electron microscopy ("TEM"). An image of the mixture at a magnification of 10,000 is shown in FIG. 5. As shown, the mixture contains many domains formed by Lotader® AX 8900, the size of which is in the nanoscale, which are presented in the form of smaller darkened areas.

Example 52

Fibers were obtained as described in Example 51, except that the concentration of Lotader® AX8900 was 0.5% and the spinning disk speed was 2000 m / min. Fibers were collected at 2000 m / min, and spinning was carried out at 3000 m / min and a productivity of 0.16 grams per hole per minute, resulting in a degree of stretching of 5810. Ten (10) samples were obtained according to the recipe of Example 52, for which then determined the tensile strength and elongation. The results (averaged) are presented below.

Table 9 Properties of the fibers obtained in Example 52 Etc. # Poly-epoxy modifier (wt.%) Pace. fiber extrusion (° C) Spinning Disc Speed (m / min) Diameter (μm) Elongation (%) Tensile strength g / g Max. degree of traction Moisture content before spinning (parts per million) 52 0.5 240 ° C 2000 13.6 69,4 2,8 5810 72

Example 53

The possibility of obtaining a spunbond web from fibers obtained from a mixture of 88.7 wt.% Polylactic acid (PLA 6201 D, Natureworks®), 9.8 wt.% PP3155 (Exxon-Mobil) and 1.5 wt.% Polyepoxide modifier was investigated . The polyepoxide modifier was a triple copolymer of ethylene, methyl acrylate and glycidyl methacrylate (Lotader® AX8950, Arkema). The polymers were fed into an extruder with two screws meshed and rotating in the same direction (64 mm, 2240 mm long). The extruder included 8 zones, respectively numbered 1-8, starting from the feed hopper to the extrusion head. The polymers were sent to first cylinder # 1 through a gravity feeder at a total flow rate of 550 pounds per hour (approximately 249.5 kg per hour). The extrusion head used for extrusion of the polymer had 24 die holes (3 mm in diameter). After formation, the extruded polymer was cooled in water and granulated using a Gala Underwater granulator. The screw speed was 350 rpm. Then the granules were sent to an extruder, heated to a temperature of 240 ° C. The extruder productivity was 0.7 grams per hole per minute (holes 0.6 mm in size, using a spinneret kit having 100 holes per inch). The melt was extruded through a spinneret assembly, producing continuous fibers, which were then rapidly cooled by air at a temperature of 25 ° C, driven by a blower. Then, the continuous fibers were stretched mechanically using a fiber stretcher, and wound onto a moving spinning wire at a drawing speed of 4600 meters per minute, resulting in a stretch ratio of 2025. Then, the fibers were thermally bonded using a heated calender shaft to obtain continuous spanbond canvas. The resulting web was wound onto a winding device, and then its properties were examined.

Example 54

Spunbond webs were prepared as described in Example 53, except that the polymer mixture was a plasticized PMA consisting of 92 wt.% Polylactic acid (PLA 6201 D, Natureworks®), 2 wt.% Pluriol WI-285 (BASF ), 2.7 wt.% Carbowax 8000 (Dow) and 3.3 wt.% Fusabond MD-353D (DuPont), and the stretch speed was 3200 m / min, resulting in a stretch ratio of 1410. The resulting webs were wound winding devices for researching their properties.

Example 55

Spunbond webs were prepared as described in Example 53, except that the polymer was 100% (w / w) polylactic acid (PLA 6201 D, Natureworks®), which was not subjected to compounding, and the stretching speed was 3400 m / min ( holes with a size of 0.35 mm, using a spinneret kit having 100 holes per inch), resulting in a degree of extension of 509. The resulting webs were wound on winding devices to conduct studies of their properties.

According to the excerpts of Examples 53-55, ten (10) samples were obtained, for which the tensile and elongation strengths were then determined in the longitudinal (machine) direction (MN) and the transverse direction (PN) of the web. The results (averaged) are presented below. To account for the difference in the density of the webs, the tensile strength values were normalized by density.

Table 10 Properties of the fibers obtained in examples 53-55 Etc. # Type of mixture Density (g / sq.m) Normalized tensile strength in MN (g / (2 ”* g / m2)) Normalized tensile strength in PN (g / (2 ”* g / sq.m)) Elongation in MN (%) Elongation in PN (%) 53 PMK, PP3155, Lotader® AX8950 27.5 284 49 24 44 54 Plasticized PMK 22.0 132 32 eighteen 52 55 100 wt.% PMK 25.0 181 47 four fifteen

Although the invention has been described in detail using specific examples of implementation, after reading the proposed description, specialists in the art should understand that the presented examples of implementation may have equivalents, as well as changes and modifications may be made to them. Accordingly, the scope of the present invention is defined by the appended claims and any equivalents thereof.

Claims (22)

1. A method of obtaining fibers from polylactic acid, including:
melt mixing of polylactic acid with a polyepoxide modifier and a polymer strengthening additive to form a thermoplastic composition, wherein the strengthening additive is dispersed as discrete phase domains in the continuous phase of polylactic acid, melt mixing is carried out at a temperature above the melting temperature of polylactic acid, but below a temperature of approximately approximately 230 ° C, and the number-average molecular weight of the polyepoxide modifier is from about 7500 to pr approximately 250,000 grams per mole, and the amount of polyepoxide modifier is from about 0.01 mass. % to about 10 mass. % by weight of polylactic acid;
subsequent extrusion of the thermoplastic composition at a temperature exceeding approximately 230 ° C, which contributes to the reaction of the polyepoxide modifier with polylactic acid; and
passing the reacted composition through the extrusion die to form a fiber. 2. The method of claim 1, wherein the polyepoxide modifier comprises an epoxide functionalized (meth) acrylic monomer component, for example glycidyl acrylate, glycidyl methacrylate, or a combination thereof. 3. The method according to claim 2, in which the polyepoxide modifier is a copolymer that includes a monomer component based on epoxide functionalized (meth) acrylic acid and an additional monomer component. 4. The method of claim 3, wherein the additional monomer component comprises an α-olefin monomer. 5. The method of claim 4, wherein the copolymer further comprises an (meth) acrylic monomer component that does not contain an epoxy group. 6. The method according to claim 1, in which the polyepoxide modifier is a triple copolymer of ethylene, methacrylate and glycidyl methacrylate. 7. The method of claim 1, wherein the number average molecular weight of the polyepoxide modifier is from about 15,000 to about 150,000 grams per mole. 8. The method of claim 1, wherein the equivalent weight of the epoxide in the polyepoxide modifier is from about 200 to about 10,000 grams per mole. 9. The method according to p. 1, in which polylactic acid is approximately 70 mass. % or more by weight of the thermoplastic composition. 10. The method according to p. 1, in which the melt mixing is carried out at a temperature of from about 180 ° C to about 220 ° C, and the extrusion of the thermoplastic composition is carried out at a temperature of from about 235 ° C to about 300 ° C. 11. The method of claim 1, wherein the glass transition temperature of the thermoplastic composition is from about 55 ° C to about 65 ° C. 12. The method of claim 1, wherein the melt-mixed composition comprises a plurality of discrete domains dispersed in a continuous phase, the discrete domains containing a polyepoxide modifier and the continuous phase containing polylactic acid. 13. The method according to p. 12, in which the size of the domains is from about 10 to about 1000 nanometers. 14. The method according to p. 1, in which the moisture content in polylactic acid before mixing in the melt is from about 1 to about 100 parts per million, and the moisture content in the thermoplastic composition before extrusion is from about 100 to about 500 parts per million . 15. The method according to p. 1, in which the polymer reinforcing additive is a polyolefin. 16. Fiber from polylactic acid obtained by the method according to any one of the preceding paragraphs. 17. A fiber of polylactic acid, the average diameter of which is from about 5 to about 25 micrometers, and the fiber includes a thermoplastic composition obtained by reacting polylactic acid with a polyepoxide modifier, where the polyepoxide modifier includes a copolymer that contains an epoxide-modified (meth) acrylic monomer component and an olefin monomer component, and the glass transition temperature of the fiber is from about 55 ° C to about 65 ° C, and the elongation of the fibers at peak load is approximately 50% or more, and the tensile strength is from about 0.75 to about 6 grams-force per denier. 18. The polylactic acid fiber of claim 16, wherein the fiber elongation at peak load is from about 100% to about 350%, and the tensile strength is from about 1.5 to about 3.5 gram-denier. 19. The fiber from polylactic acid according to claim 16, wherein the thermoplastic composition comprises a plurality of discrete domains dispersed in a continuous phase, the discrete domains containing a polyepoxide modifier and the continuous phase containing polylactic acid. 20. A nonwoven fabric comprising fiber according to any one of paragraphs 16-19. 21. An absorbent product containing a nonwoven fabric according to claim 20. 22. The absorbent article of claim 21, comprising a layer substantially impervious to liquid, a layer permeable to liquid, and an absorbent inner layer.

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