JP4725613B2 - Resin composition and molded article, film and fiber comprising the same - Google Patents

Description

  The present invention relates to a resin composition comprising a polylactic acid resin and a polyacetal resin, and having excellent moldability, processability, mechanical properties, heat resistance, and transparency.

  Polylactic acid has a high melting point and is expected to be a biodegradable polymer that is melt-moldable and excellent in practical use. However, polylactic acid has a low crystallization rate, and there is a limit to use it as a molded product after crystallization. For example, in the case of injection molding, not only a long molding cycle time and post-molding heat treatment are required, but there is a large practical problem such as large deformation during molding and heat treatment.

  Polyacetal resin is a resin with excellent balance such as mechanical properties and moldability, and is widely used as an injection-molded product, but it is difficult to process into film or fiber due to its high crystallization speed, It was limited.

  Mixing two or more polymers is widely known as a polymer blend or polymer alloy and is widely used to improve the shortcomings of individual polymers. However, when two polymers are mixed, many are separated into individual phases and therefore tend to exhibit poor properties.

  On the other hand, two kinds of polymers rarely form a uniform amorphous phase. This type is generally described as compatible or miscible and is expected to exhibit excellent properties, but there are few examples.

  As the polymer compatible with polylactic acid, only a few examples such as polyethylene glycol (for example, Non-Patent Document 1) and polymethyl methacrylate (for example, Non-Patent Document 2) are known. Moreover, only a few examples such as polyvinylphenol (for example, Non-Patent Document 3) are known as polymers compatible with polyacetal.

Patent Document 1 discloses a resin composition containing an aliphatic polyester and a small amount of formaldehyde for the purpose of imparting biodegradability to polyacetal. Among them, polylactic acid is used as an example of an aliphatic polyester. Although examples are disclosed, there is no disclosure regarding the compatibility of polylactic acid and polyacetal. In addition, the invention described in the publication mainly aims to impart biodegradability of the polyacetal resin in a composition containing a relatively large amount of polyacetal resin, and thus obtains a composition that makes use of the characteristics of the polyacetal resin in ordinary applications. When trying to do so, the durability is poor, which is not preferable for practical use.
Japanese Patent Laid-Open No. 5-43772 Polymer 37 (26), 5849-5857 (1996) Polymer 39 (26), 6891-6897 (1998) Polymer 33 (4), 760-766 (1992)

  An object of the present invention is to provide a resin composition excellent in moldability, processability, mechanical properties, heat resistance, and transparency.

  The present inventors have found that a polylactic acid resin and a polyacetal resin form a compatible blend, and a resin composition obtained by mixing both has excellent characteristics.

That is, the present invention
1. Of the total lactic acid component of the polylactic acid resin, when the L-form has a total of 100 parts by weight of the polylactic acid resin and polyacetal resin or D-isomer contained 98% or more is contained 98% or more, the polylactic acid resin 60 A resin composition which is a compatible blend of a polylactic acid resin and a polyacetal resin comprising 40 parts by weight and 40 to 60 parts by weight of a polyacetal resin.
2. Of the total lactic acid component of the polylactic acid resin, when the total of the polylactic acid resin containing 98% or more of the L form or 98% or more of the D form and the polyacetal resin is 100 parts by weight, the polylactic acid resin is 40 % by weight. A resin composition which is a compatible blend of a polylactic acid resin and a polyacetal resin, comprising less than 1 part by weight and 1 part by weight or more and a polyacetal resin of more than 60 parts by weight and less than 99 parts by weight.
3. Crystallization temperature during cooling from the polyacetal resin of the resin composition, the resin composition according to 1, which is 4 ° C. or higher temperature lower than the crystallization temperature during cooling of the polyacetal resin alone was used.
4). 3. The resin composition according to 2, wherein the crystallization temperature at the time of temperature reduction derived from the polyacetal resin of the resin composition is lower by 0.5 ° C. or more than the crystallization temperature at the time of temperature decrease of the used polyacetal resin alone.
5. The resin composition according to any one of 1 to 4 , wherein the formaldehyde content in the resin composition is less than 500 ppm with respect to the polyacetal resin.
6). The resin composition according to any one of 1 to 5 , wherein the polyacetal resin is a polyacetal copolymer.
7). 7. The resin composition according to any one of 1 to 6 , wherein a film having a light transmittance of 90% or more and a haze value of 50% or less and 0% or more at a film thickness of 100 μm can be formed.
8). 8. The resin composition according to any one of 1 to 7 , wherein the polylactic acid resin has a weight average molecular weight of 80,000 or more and 280,000 or less.
It is.

  Furthermore, it is a molded article, a film or a fiber comprising any of the resin compositions described above.

  According to the present invention, a resin composition excellent in moldability, workability, mechanical properties, heat resistance, and transparency can be obtained.

  Hereinafter, the present invention will be described in detail.

  The polylactic acid resin used in the present invention is a polymer mainly composed of L-lactic acid and / or D-lactic acid, but may contain other copolymerization components other than lactic acid. Other monomer units include ethylene glycol, propylene glycol, butanediol, heptanediol, hexanediol, octanediol, nonanediol, decanediol, 1,4-cyclohexanedimethanol, neopentyl glycol, glycerin, pentane. Glycol compounds such as erythritol, bisphenol A, polyethylene glycol, polypropylene glycol and polytetramethylene glycol, oxalic acid, adipic acid, sebacic acid, azelaic acid, dodecanedioic acid, malonic acid, glutaric acid, cyclohexanedicarboxylic acid, terephthalic acid , Isophthalic acid, phthalic acid, naphthalenedicarboxylic acid, bis (p-carboxyphenyl) methane, anthracene dicarboxylic acid, 4,4′-diphenyl ether dicarbohydrate Acids, dicarboxylic acids such as 5-sodium sulfoisophthalic acid, 5-tetrabutylphosphonium isophthalic acid, glycolic acid, hydroxypropionic acid, hydroxybutyric acid, hydroxyvaleric acid, hydroxycaproic acid, hydroxybenzoic acid and other hydroxycarboxylic acids, caprolactone, Examples include lactones such as valerolactone, propiolactone, undecalactone, and 1,5-oxepan-2-one. Such a copolymer component is preferably contained in an amount of usually 30 mol% or less, preferably 10 mol% or less, in all monomer components.

In the present invention, in order to obtain a resin composition having particularly high heat resistance, it is preferable to use a polylactic acid resin having a high optical purity of the lactic acid component. Among the total lactic acid components of the polylactic acid resin, those containing 98% or more of L- form or 98% or more of D-form are used . Moreover, the upper limit of the content of L-form or D-form is usually 100% or less.

  As a method for producing the polylactic acid resin, a known polymerization method can be used, and examples thereof include a direct polymerization method from lactic acid and a ring-opening polymerization method via lactide.

  The molecular weight and molecular weight distribution of the polylactic acid resin are not particularly limited as long as it can be substantially molded, but the weight average molecular weight is usually 10,000 or more, preferably 40,000 or more, and further 80,000. It is preferable that it is 280,000 or less. The weight average molecular weight here refers to the molecular weight in terms of polymethyl methacrylate (PMMA) measured by gel permeation chromatography.

  The melting point of the polylactic acid resin is not particularly limited, but is preferably 120 ° C. or higher, and more preferably 150 ° C. or higher.

  The polyacetal resin used in the present invention is a polymer having an oxymethylene unit as a main repeating unit, and even a so-called polyacetal homopolymer obtained by polymerization reaction using formaldehyde or trioxane as a main raw material is mainly composed of an oxymethylene unit. Which may be any so-called polyacetal copolymer containing not more than 15% by weight of oxyalkylene units having 2 to 8 adjacent carbon atoms in the main chain, and also containing other structural units, Any of a block copolymer, a terpolymer, and a crosslinked polymer may be used, and these may be used alone or in combination of two or more.

  Among them, a polyacetal copolymer is preferable, and a polyacetal copolymer containing 2% by weight or less of an oxyalkylene unit having 2 adjacent carbon atoms in the main chain or an oxyalkylene unit having 4 adjacent carbon atoms in the main chain More preferably 5% by weight or less of a polyacetal copolymer containing 1.4% by weight or less and 0.2% by weight or more of an oxyalkylene unit having two adjacent carbon atoms in the main chain or in the main chain Particularly preferred is a polyacetal copolymer containing 3% by weight or more and 0.5% by weight or more of an oxyalkylene unit having 4 adjacent carbon atoms.

  There is no restriction | limiting in particular in the manufacturing method of the polyacetal resin in this invention, It can manufacture by a well-known method. As an example of a typical method for producing a polyacetal homopolymer, high-purity formaldehyde is introduced into an organic solvent containing a basic polymerization catalyst such as an organic amine, an organic or inorganic tin compound, or a metal hydroxide. Examples of the method include polymerizing and filtering the polymer, followed by heating in acetic anhydride in the presence of sodium acetate to acetylate the polymer terminal.

  As a typical method for producing a polyacetal copolymer, a high purity trioxane and a copolymer component such as ethylene oxide or 1,3-dioxolane are introduced into an organic solvent such as cyclohexane to form a boron trifluoride diethyl ether complex. After cationic polymerization using such Lewis acid catalyst, trioxane and copolymerization into a self-cleaning stirrer without using a solvent, or using a manufacturing method by deactivating the catalyst and stabilizing the end groups Examples thereof include a method in which a component and a catalyst are introduced and bulk polymerization is performed, and then an unstable terminal is further decomposed and removed.

  The viscosity of these polymers is not particularly limited as long as it can be used as a molding material, but the melt flow rate (MFR) can be measured by the ASTM D1238 method, and the MFR is in the range of 1.0 to 50 g / 10 min. The thing of 1.5-35 g / 10min is especially preferable.

  The polyacetal resin in the present invention includes 2,2′-methylenebis (4-methyl-6-tert-butylphenol), calcium ricinoleate, cyanoguanazine, hexamethylenebis (3,5-t-butyl-4-hydroxyhydrocyanate ), Melamine-formaldehyde resin, nylon 6/66, nylon 66/610/6, nylon 612/6, tetrakis [methylene (3,5-di-t-butyl-4-hydroxyhydrocyanate)] methane, 1, 6-hexanediol bis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate], triethylene glycol [3- (3,5-di-t-butyl-5-methyl-4- Hydroxyphenyl) propionate] is preferably contained.

  In the resin composition of the present invention, as will be described later, a polylactic acid resin and a polyacetal resin form a compatible compound, thereby obtaining unique characteristics that are not seen in the case of a composition that is not normally compatible. The composition is excellent in moldability, processability, mechanical properties, heat resistance, and transparency, but the particularly effective properties differ depending on the blended composition of polylactic acid and polyacetal resin.

  In a resin composition comprising 60 to 40 parts by weight of polylactic acid resin and 40 to 60 parts by weight of polyacetal resin when the total of the polylactic acid resin and the polyacetal resin is 100 parts by weight, the polylactic acid resin and the polyacetal resin A resin composition having a good balance of these properties can be obtained.

  When the total amount of the polylactic acid resin and the polyacetal resin is 100 parts by weight, in the resin composition formed by blending less than 40 parts by weight of the polylactic acid resin and 1 part by weight or more and less than 99 parts by weight of the polyacetal resin, It is possible to improve the properties of the polyacetal resin, and in particular, it is effective for improving processability and mechanical properties.

  In the case of using a polyacetal resin, it is preferable not to add formaldehyde that has a high possibility of exerting a strong influence on the properties of the composition itself, such as impairing the durability of the composition by promoting the decomposition of the polyacetal. Considering the formaldehyde contained in the polyacetal resin itself, it is preferable to keep it at most less than 500 ppm, more preferably less than 250 ppm, and particularly preferably less than 100 ppm with respect to the polyacetal resin. In order to achieve such a formaldehyde content, as described above, after the polymerization of the polyacetal homopolymer, the polymer terminal is acetylated, or after the polymerization of the polyacetal copolymer, the unstable terminal is decomposed and removed. It is preferable to use a polyacetal resin subjected to the above. The formaldehyde content in the resin composition is determined by stirring 1 g of powder obtained by pulverizing the resin composition in 100 ml of water at 50 ° C. for 6 hours, extracting formaldehyde, and quantifying it by the acetylacetone method. Can be measured.

  The resin composition of the present invention is characterized by comprising a compatible blend of a polylactic acid resin and a polyacetal resin. As used herein, “compatible” is used to describe a mixture of polymers that forms a homogeneous phase within the amorphous phase at the molecular level. When one or both of the formulations forms both a crystalline phase and an amorphous phase, compatible means that the amorphous phase is molecularly mixed.

  The determination of compatibility in a formulation can be made in several ways.

  The most common method for judging the compatibility is a method for judging by the glass transition temperature. In compatible formulations, the glass transition temperature varies from that of each individual and often exhibits a single glass transition temperature. This method can also be used for a blend of a polylactic acid resin and a polyacetal resin. In the resin composition of the present invention, the resin composition exhibits a temperature lower than the glass transition temperature of the polylactic acid resin alone. As a method for measuring the glass transition temperature, any of a method of measuring by a differential scanning calorimeter (DSC) and a method of measuring by a dynamic viscoelasticity test can be used.

  However, since the polyacetal resin is highly crystalline, there is a problem that the glass transition temperature becomes unclear when the content of the polyacetal resin is large. In this case, the crystallization temperature of the polyacetal resin can be used as the compatibility determination. When the polyacetal resin forms a compatible compound with a resin having a slower crystallization rate than the polyacetal resin itself, the crystallization rate of the polyacetal resin is lower than when the polyacetal resin is used alone. This decrease in the crystallization rate can be determined by the crystallization temperature at the time of temperature decrease measured by DSC.

  For example, Polymer 38 (25), 6135-6143 (1997) reported that a blend of poly (3-hydroxybutyrate) and polymethylene oxide (polyacetal), which are aliphatic polyesters, is incompatible. However, in this case, it is shown that the crystallization temperature of polyacetal in the composition measured by DSC is almost the same as the crystallization temperature of polyacetal alone. On the other hand, Polymer 33 (4), 760-766 (1992) reports that polyacetal and polyvinylphenol are compatible. In this case, the crystallization temperature of polyacetal in the composition when the temperature is lowered is It has been shown that this is lower than the crystallization temperature of polyacetal alone.

  In the resin composition of the present invention, the crystallization temperature of the polyacetal resin in the resin composition when the temperature falls is lower than the crystallization temperature of the polyacetal resin alone. The preferred decrease in crystallization temperature depends on the composition. The crystallization temperature tends to decrease as the optical purity of the polylactic acid resin used increases.

  When the total of polylactic acid resin and polyacetal resin is 100 parts by weight, when blending 60 to 40 parts by weight of polylactic acid resin and 40 to 60 parts by weight of polyacetal resin, measured by DSC at a cooling rate of 20 ° C./minute The decrease in the crystallization temperature of the polyacetal resin is preferably 2 ° C. or higher, more preferably 4 ° C. or higher. When the total of the polylactic acid resin and the polyacetal resin is 100 parts by weight, when the polylactic acid resin is less than 40 parts by weight and 1 part by weight or more and more than 60 parts by weight of the polyacetal resin is less than 99 parts by weight, the temperature lowering rate by DSC The decrease in the crystallization temperature of the polyacetal resin measured at 20 ° C./min is preferably 0.2 ° C. or higher, and more preferably 0.5 ° C. or higher.

  Also, when a film is made from a compatible blend, it is optically clear, whereas a film made from an incompatible blend is generally opaque. This method can also be used as a compatibility judgment. However, when both are crystalline resins, such as a blend of polylactic acid resin and polyacetal resin, it may become opaque due to crystallization of one of them, so the film is opaque. However, in the present invention, when the content of polylactic acid is relatively large, the determination of compatibility is effective.

  For example, in the resin composition of the present invention, a film having a light transmittance of 90% to 100% and a haze value of 0% to 50% at a film thickness of 100 μm even when the content of polylactic acid is 60 parts by weight or less. It can be formed, and by quenching to a lower temperature, a substantially transparent film can be obtained even in a region where the content of polylactic acid is low.

  In addition, the substantially transparent film obtained in this way has a feature that it has excellent toughness and post-processability such as stretching because of the large amount of compatibilized polymer. The same applies to other molded articles such as fibers.

  For the present invention, fillers (glass fiber, carbon fiber, natural fiber, organic fiber, ceramic fiber, ceramic beads, asbestos, wollastonite, talc, clay, mica, sericite, as long as the object of the present invention is not impaired. Zeolite, bentonite, dolomite, kaolin, finely divided silicic acid, feldspar powder, potassium titanate, shirasu balloon, calcium carbonate, magnesium carbonate, barium sulfate, calcium oxide, aluminum oxide, titanium oxide, aluminum silicate, silicon oxide, gypsum, Novacurite , Dosonite and clay), stabilizers (antioxidants, ultraviolet absorbers, etc.), lubricants, mold release agents, flame retardants (bromine flame retardants, phosphorus flame retardants, antimony compounds), colorants including dyes and pigments Nucleating agents can be added.

  In contrast to the present invention, other thermoplastic resins (for example, polyethylene, polypropylene, acrylic resin, polyamide, polyphenylene sulfide resin, polyetheretherketone resin, polyester, polysulfone, polyphenylene oxide, polyimide, as long as the object of the present invention is not impaired. , Polyetherimide, etc.) and thermosetting resins (eg phenolic resin, melamine resin, polyester resin, silicone resin, epoxy resin etc.) and soft thermoplastic resins (eg ethylene / glycidyl methacrylate copolymer, polyester elastomer, polyamide elastomer, Ethylene / propylene terpolymer, ethylene / butene-1 copolymer, etc.) and the like.

  The method for producing the composition of the present invention is not particularly limited. For example, after pre-blending a polylactic acid resin, a polyacetal resin and other additives as necessary, at a melting point or higher, uniaxial or biaxial extrusion A method of uniformly melting and kneading with a machine or a method of removing the solvent after mixing in a solution is preferably used.

  The resin composition of the present invention is a compatible composition having unique characteristics, and can be processed into various molded products and used by methods such as injection molding and extrusion molding. As molded products, it can be used as injection molded products, extrusion molded products, blow molded products, films, fibers, sheets, etc., as films and sheets, various films and sheets such as unstretched, uniaxially stretched and biaxially stretched, As fibers, various fibers such as undrawn yarns, drawn yarns, and super-drawn yarns can be used as woven fabrics, knitted fabrics, nonwoven fabrics (spunbond, melt blown, staples), ropes, and nets. Moreover, these articles can be used as electrical / electronic parts, building members, automobile parts, machine parts, daily necessities, and the like.

  Specifically, mobile terminals such as relay cases, coil bobbins, optical pickup chassis, motor cases, notebook computer housings and internal parts, CRT display housings and internal parts, printer housings and internal parts, mobile phones, mobile personal computers, handheld mobiles Housing and internal components, recording media (CD, DVD, PD, FDD, etc.) drive housing and internal components, copier housing and internal components, facsimile housing and internal components, parabolic antennas and other electrical / electronic components Can be mentioned. Furthermore, audio equipment parts such as VTR parts, TV parts, irons, hair dryers, rice cooker parts, microwave oven parts, acoustic parts, video cameras, audio / laser disks (registered trademark) / compact disks, lighting parts, refrigerator parts, Examples include home and office electrical product parts such as air conditioner parts, typewriter parts, and word processor parts. Also, housings and internal parts of electronic musical instruments, home game machines, portable game machines, various gears, various cases, sensors, LEP lamps, connectors, sockets, resistors, relay cases, switches, coil bobbins, capacitors, variable capacitor cases, Optical pickups, oscillators, various terminal boards, transformers, plugs, printed wiring boards, tuners, speakers, microphones, headphones, small motors, magnetic head bases, power modules, semiconductors, liquid crystals, FDD carriages, FDD chassis, motor brush holders , Electrical and electronic parts such as transformer members, coil bobbins, sash doors, blind curtain parts, piping joints, curtain liners, blind parts, gas meter parts, water meter parts, water heater parts, roof panels, Hot walls, adjusters, plastic bundles, ceiling fishing gear, staircases, doors, floors and other building materials, fishing lines, fishing nets, seaweed aquaculture nets, fishing bait bags and other marine products, vegetation nets, vegetation mats, weedproof bags, protection Grass net, curing sheet, slope protection sheet, fly ash holding sheet, drain sheet, water retention sheet, sludge / sludge dewatering bag, concrete formwork and other civil engineering related parts, air flow meter, air pump, thermostat housing, engine mount, ignition hobbin , Ignition case, clutch bobbin, sensor housing, idle speed control valve, vacuum switching valve, ECU housing, vacuum pump case, inhibitor switch, rotation sensor, acceleration sensor, distributor cap, coil base, AB Actuator case, radiator tank top and bottom, cooling fan, fan shroud, engine cover, cylinder head cover, oil cap, oil pan, oil filter, fuel cap, fuel strainer, distributor cap, vapor canister housing, air cleaner housing, Timing belt covers, brake booster parts, various cases, various tubes, various tanks, various hoses, various clips, various valves, various pipes and other automotive underhood parts, torque control levers, safety belt parts, register blades, washer levers, Window regulator handle, knob of window regulator handle, passing light lever, samba Automotive interior parts such as Iser brackets, various motor housings, roof rails, fenders, garnishes, bumpers, door mirror stays, spoilers, hood louvers, wheel covers, wheel caps, grill apron cover frames, lamp reflectors, lamp bezels, door handles, etc. Automotive exterior parts, wire harness connectors, SMJ connectors, PCB connectors, door grommet connectors and other automotive connectors, gears, screws, springs, bearings, levers, key stems, cams, ratchets, rollers, water supply parts, toy parts, fans, Tegs, pipes, cleaning jigs, motor parts, microscopes, binoculars, cameras, watches and other mechanical parts, multi-films, tunnel films, bird protection sheets, vegetation protection nonwoven fabrics, seedlings Pot, vegetation pile, seed string tape, germination sheet, house lining sheet, farm-bi fastener, slow-release fertilizer, root-proof sheet, garden net, insect net, young tree net, printed laminate, fertilizer bag, sample Agricultural materials such as bags, sandbags, beast damage prevention nets, incentive straps, windproof nets, disposable diapers, sanitary wrapping materials, hygiene products such as cotton swabs, towels, and toilet seat wipes, medical non-woven fabrics (stitching reinforcement, adhesion prevention membranes, Prosthetic repair materials), wound dressing materials, wound tape bandages, sticky material base fabric, surgical sutures, fracture reinforcements, medical films and other medical supplies, calendars, stationery, clothing, food packaging films, trays , Blisters, knives, forks, spoons, tubes, plastic cans, pouches, containers, tanks, baskets and other containers, tableware, hot-fill containers, microwave cooking containers cosmetics , Wrap, foam buffer, paper lami, shampoo bottle, beverage bottle, cup, candy packaging, shrink label, lid material, envelope with window, fruit basket, hand tape, easy peel packaging, egg pack, HDD packaging, Compost bags, recording media packaging, shopping bags, containers and packaging such as wrapping films for electrical and electronic parts, natural fiber composites, polo shirts, T-shirts, inners, uniforms, sweaters, socks, ties and other clothing, curtains, Interior items such as chairs, carpets, tablecloths, futons, wallpaper, carrier tapes, print laminates, thermal stencil printing films, release films, porous films, container bags, credit cards, cash cards, ID cards, IC cards, paper, leather, non-woven fabrics, etc. Binder of powder, such as hot melt binder, magnetic material, zinc sulfide, electrode material, optical element, conductive embossed tape, IC tray, golf tee, garbage bag, plastic bag, various nets, toothbrush, stationery, draining net, body Towel, hand towel, tea pack, furoshiki, drain filter, clear file, coat agent, adhesive, bag, chair, table, cooler box, kumade, hose reel, planter, hose nozzle, dining table, desk surface, furniture panel Useful as kitchen cabinets, pen caps, gas lighters, etc.

  EXAMPLES Next, although an Example demonstrates this invention further in detail, these do not limit this invention.

Example 1 and Comparative Example 1
Poly-L lactic acid resin having a D-form content of 1.2%, a weight average molecular weight in terms of PMMA of 160,000, and a melt index value measured at 190 ° C. of 27 g / 10 min and a melting point of 170 ° C. A polyacetal copolymer (Amiras S731 manufactured by Toray Industries, Inc.) was blended at the ratio shown in Table 1, and melt kneaded at a temperature of 210 ° C. and a rotation speed of 50 rpm with a 40 mm diameter single screw extruder to obtain a resin composition. .

  The glass transition temperature (Tg) of the obtained resin composition and the crystallization temperature (Tc) when the polyacetal resin was cooled were measured using a differential scanning calorimeter (DSC) (manufactured by PerkinElmer Co., Ltd.) Measured in minutes. The results are shown in Table 1. Tg decreases as the content of polyacetal resin increases. In addition, Tc decreases with an increase in the content of polylactic acid resin.

  Moreover, the obtained composition was heated at 200 ° C. for 2 minutes, then pressed, and then cooled in ice water to obtain a film having a thickness of 100 μm, and the transparency of the film was judged visually. The results are shown in Table 1. Experiment Nos. 1-1 and 1-7 are comparative data. Moreover, the photograph of the film obtained by experiment No.1-1, 1-2, 1-4, 1-5, 1-7 is shown in FIG. In the figure, the upper left is a film with a polylactic acid / polyacetal composition ratio of 90/10 (Experiment No. 1-2), the middle left is a film with a composition ratio of 70/30 (Experiment No. 1-4), and the lower left is the composition. It is a film having a ratio of 50/50 (Experiment No. 1-5). The upper right is a film of polylactic acid alone (experiment No. 1-1), and the lower right is a film of polyacetal alone (experiment No. 1-7). The film with a composition ratio of 90/10, the film with a composition ratio of 70/30, and the film of polylactic acid alone have a clear base and high transparency, but the remaining films are opaque and the base is not visible. In this method, a transparent film can be obtained up to a polyacetal content of 30%.

  Next, the light transmittance and haze value of the obtained film were determined in accordance with JIS-K6714. T.A. Measurements were made using an R meter. The results are shown in Table 2. A film having a composition ratio of 90/10, a film of 80/20, a film of 70/30, and a film of polylactic acid alone have a light transmittance of 95% or more and a haze value of 10% or less. Further, even in a film having a composition ratio of 50/50 and a film having a ratio of 30/70, the light transmittance is 90% or more and the haze value is 50% or less, whereas the film of polyacetal alone has a light transmittance of 90%. The haze value is 85%.

  Further, the obtained resin composition was injection-molded at a cylinder temperature of 210 ° C. and a mold temperature of 40 ° C., tensile test pieces were obtained, and a tensile test was performed according to ASTM method D638. Further, the degree of deformation of the tensile test piece when it was heated at 140 ° C. for 1 hour was visually observed. The results are shown in Table 3. The resin composition of the present invention has excellent mechanical properties and heat resistance as compared with each resin composition.

Example 2 and Comparative Example 2
Poly-L lactic acid resin having a D-form content of 1.2%, a PMMA equivalent weight average molecular weight of 280,000, a melt index value measured at 190 ° C. of 9 g / 10 min, and a melting point of 170 ° C. A resin composition was obtained in the same manner as in Example 1 except that a polyacetal copolymer (Amiras S761 manufactured by Toray Industries, Inc.) was blended in the ratio shown in Table 4. The Tg of the obtained resin composition and the Tc of the polyacetal resin of the composition were measured in the same manner as in Example 1. The results are shown in Table 4. Experiments 2-1 and 2-5 are comparative data. Similar to Example 1, a decrease in Tg and a decrease in Tc are observed. Further, when the obtained resin composition was melt-spun at a spinning temperature of 210 ° C. and a spinning speed of 1000 m / min, the spinnability was good except for the polyacetal resin alone (2-5), but the polyacetal resin alone Then, thread breakage occurred frequently.

Comparative Example 3
A poly-L lactic acid resin having a D-form content of 8%, a PMMA equivalent weight average molecular weight of 180,000, and a polyacetal copolymer having a melt index value measured at 190 ° C. of 27 g / 10 min and a melting point of 170 ° C. A resin composition was obtained in the same manner as in Example 1 except that (Amiras S731 manufactured by Toray Industries, Inc.) was blended at the ratio shown in Table 5. The Tg of the obtained resin composition and the Tc of the polyacetal resin of the composition were measured in the same manner as in Example 1. The results are shown in Table 5. Experiment Nos. 3-1 and 3-5 are comparative data. Although the fall of Tg and the fall of Tc are seen like Example 1, the grade of a fall is small.

Comparative Example 4
80 parts by weight of poly-L lactic acid resin having a D-form content of 1.2% and a weight-average molecular weight in terms of PMMA of 160,000 and 20 parts by weight of nylon 6 (Toray Milan CM1010) using a single screw extruder of 40 mm diameter Then, melt kneading was performed under the conditions of a temperature of 240 ° C. and a rotation speed of 50 rpm to obtain a resin composition.

  The resulting resin composition had a glass transition temperature (Tg) derived from the poly-L lactic acid resin of 66 ° C. Therefore, it is considered that poly L lactic acid resin and nylon 6 are incompatible. Further, the obtained composition was heated at 230 ° C. for 2 minutes, pressed, and then cooled in ice water to obtain a film having a thickness of 100 μm. The film was opaque, the light transmittance of the film was 69%, and the haze value was 92%.

Comparative Example 5
Polyacetal copolymer (Amiras S731 manufactured by Toray Industries, Inc.) having a melt index value measured at 190 ° C. of 27 g / 10 min and a melting point of 170 ° C. and polymethacrylic acid having a melt index value measured at 230 ° C. of 35 g / 10 min 20 parts by weight of methyl resin (Sumipex LG35 manufactured by Sumitomo Chemical Co., Ltd.) was melt kneaded with a 40 mm diameter single screw extruder under the conditions of a temperature of 200 ° C. and a rotation speed of 50 rpm to obtain a resin composition.

  Tc of the polyacetal resin of the obtained resin composition was 140 ° C. Therefore, it is considered that the polyacetal resin and the polymethyl methacrylate resin are incompatible. The obtained composition was heated at 200 ° C. for 2 minutes, then pressed, and then cooled in ice water to obtain a film having a thickness of 100 μm. The film was opaque, the light transmittance of the film was 59%, and the haze value was 90%.

Example 3
1 g of powder obtained by pulverizing the resin composition obtained by blending the polylactic acid resin and the polyacetal resin obtained in Examples 1 and 2 and Comparative Example 3 was stirred in 50 ml of water at 50 ° C. for 6 hours. Extracted formaldehyde. Table 6 shows the results of quantification of this by the acetylacetone method. The amount of formaldehyde in any composition was less than 250 ppm with respect to the polyacetal resin.

Example 4
The content of D-form is 1.2%, the weight average molecular weight in terms of PMMA is 160 parts by weight, and the melt index value measured at 190 ° C. is 9 g / 10 min and the melting point is 170. 50 parts by weight of polyacetal copolymer (containing 1.5% by weight of oxyalkylene units having two adjacent carbon atoms in the main chain) and 0.001 part by weight of 30% by weight of formalin aqueous solution, 40 mm When melt kneading was performed with a single screw extruder having a temperature of 200 ° C. and a rotation speed of 50 rpm, foaming occurred, but a resin composition having a formaldehyde content of 500 ppm measured in the same manner as in Example 3 was obtained. . However, remarkable foaming accompanied by odor occurred during processing, and the film could not be formed into a molded product, and the characteristics could not be evaluated.

Comparative Example 6
A resin composition having a formaldehyde content of 500 ppm was obtained in the same manner as in Example 4 except that a poly-L lactic acid resin having a D-form content of 8% and a PMMA equivalent weight average molecular weight of 160,000 was used. It was. However, remarkable foaming accompanied by odor occurred during processing, and the film could not be formed into a molded product, and the characteristics could not be evaluated.

2 is a photograph of a film created in Example 1 and Comparative Example 1.

Claims (11)

Of the total lactic acid component of the polylactic acid resin, when the L-form has a total of 100 parts by weight of the polylactic acid resin and polyacetal resin or D-isomer contained 98% or more is contained 98% or more, the polylactic acid resin 60 A resin composition which is a compatible blend of a polylactic acid resin and a polyacetal resin comprising 40 parts by weight and 40 to 60 parts by weight of a polyacetal resin. Of the total lactic acid component of the polylactic acid resin, when the total of the polylactic acid resin containing 98% or more of the L form or 98% or more of the D form and the polyacetal resin is 100 parts by weight, the polylactic acid resin is 40 % by weight. A resin composition which is a compatible blend of a polylactic acid resin and a polyacetal resin, comprising less than 1 part by weight and 1 part by weight or more and polyacetal resin more than 60 parts by weight and less than 99 parts by weight. 2. The resin composition according to claim 1, wherein the crystallization temperature at the time of temperature decrease from the polyacetal resin of the resin composition is 4 ° C. or more lower than the crystallization temperature at the time of temperature decrease of the polyacetal resin used alone. The resin composition according to claim 2, wherein the crystallization temperature at the time of temperature decrease from the polyacetal resin of the resin composition is lower by 0.5 ° C. or more than the crystallization temperature at the time of temperature decrease of the used polyacetal resin alone. The resin composition according to any one of claims 1 to 4 , wherein the formaldehyde content in the resin composition is less than 500 ppm with respect to the polyacetal resin. The resin composition according to any one of claims 1 to 5, the polyacetal resin is characterized in that it is a polyacetal copolymer. The resin composition according to any one of claims 1 to 6 , wherein a film having a light transmittance of 90% or more and a haze value of 50% or less and 0% or more at a film thickness of 100 µm can be formed. The resin composition according to any one of claims 1 to 7 , wherein the polylactic acid resin has a weight average molecular weight of 80,000 or more and 280,000 or less. The molded article which consists of a resin composition in any one of Claims 1-8 . Film comprising the resin composition according to any one of claims 1-8. The fiber which consists of a resin composition in any one of Claims 1-8 .

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