JP2012057018A - Fiber-reinforced composite material, method for producing the same, molded product made from composite material, and laminate of molded product made from composite material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide various thermoplastic resin composite materials which especially cause improvement of mechanical properties of a sheet or a thin-walled molded product made from the composite material, and which permit level material recycling.SOLUTION: This composite material which permit level material recycling includes: a thermoplastic resin A; and a resin-fiber of a thermoplastic resin B, wherein the thermoplastic resin A is the same type of resin as the thermoplastic resin B in terms of their repeating molecular chain structures. The resin-fiber of the thermoplastic resin B has a higher processible temperature than that of the thermoplastic resin A. A blending ratio of the resin-fiber of the thermoplastic resin B is ≥1 and ≤50 wt.%. The thermoplastic resins A and B contain no fillers.

Description

  The present invention relates to a thermoplastic resin composite material having high strength and excellent recyclability, a production method thereof, a composite material molded body, and a laminate of the composite material molded body.

  Thin-walled molded products made of tube or sheet-like thermoplastic resins are used in many parts for medical products and other industrial products. There are various types of thermoplastic resins, ranging from general-purpose resins to engineering plastics and super engineering plastics. These can be used from the viewpoint of heat resistance (thermal deformation temperature) realized by, for example, further increasing the interaction between molecular chains. As a result, the mechanical properties of the material are roughly determined depending on the magnitude of the intermolecular interaction of the resin species. Methods for modifying these performances later include compounding with reinforcing materials (compositing) and compounding with other resins (alloying), etc. From the viewpoint of improving mechanical properties, the base material It is necessary to select a stronger or harder component and uniformly disperse it in the base material matrix as an alloy counterpart with a reinforcing material. However, in order to form these composite materials, not only the dispersion of the second component but also the adhesiveness at the interface between the matrix resin and the dispersed phase formed by the second component is required, either of which exists alone It is not an element to do. Inevitably, a component for interfacial adhesion is required as the third component, and the composition of the composite material becomes complicated. In some cases, this adhesive phase fraction may reverse the matrix fraction, resulting in an overturned composition, which is one of the problems in composite formation.

  In these composite materials, fiber fillers such as glass fibers and carbon fibers, plate fillers such as talc, kaolin, mica and clay, some calcium carbonates and glass beads, and glass balloons are used to improve mechanical properties. Spherical fillers are often blended, and most of these are non-organic materials.

  Now, resin materials in general, including these composite materials, are required to meet the demands for building a recycling-oriented society in some form today. Especially, in terms of materials, consideration for material recycling is inevitable. (Non-Patent Document 1). However, since composite materials containing non-organic materials as the second component are essential technologies for improving the adhesion at the organic / non-organic interface, it is possible to separate and recover the organic and non-organic components during recycling. very difficult. In addition, there is a problem of the shape change (destruction) of the filler during recycling, and down material recycling is finally possible.

  Recently, an attempt to obtain a composite material using an organic material having a specific composition or shape as a second component (filler) has been reported. For example, when blended yarn obtained by mixing the resin component of the base material with a part of the organic filler and omitting the adhesive layer as the third component (Patent Document 1) or a specific opening made of a propylene-based resin A composite obtained by laminating a net-like material having a mesh interval of 2 to 8 mm with a film made of a thermoplastic resin having a melting point lower than that of a propylene-based resin (Patent Document 2) or a thermoplastic resin fiber. There is a composite (Patent Document 3) obtained by insert-molding a knitted material into the same kind of thermoplastic resin as the thermoplastic resin. Patent Document 1 also mentions the recyclability of the composite material, and it is said that the shape retention property (fiber length) of the organic filler during recycling is excellent. Although good recyclability is presumed in Patent Document 2, the emphasis is placed on maintaining the shape of the net-like material, and improvement of the mechanical properties of the entire composite is unknown. In Patent Document 3, the improvement in tensile strength and bending rigidity is clearly stated, and good material recyclability is presumed from the configuration, but it is not specifically mentioned.

  On the other hand, the case of using organic fine fibers called nanofibers as a fibrous filler made of resin itself has been studied. In the case of the electrospinning method, which is the most well-known technique for obtaining nanofibers, if a polymer solution with the optimum concentration for spinning can be produced, resin nanofibers with a diameter of several nanometers to several tens of micrometers can be used. It's easy to get.

  As an example of combining nanofibers by electrospinning with a resin, for example, a nanofiber layer is laminated on a fiber layer made of microfiber yarn (diameter of about several hundred μm) obtained by melt spinning. A composite fiber filter (Patent Document 4) and a nonwoven fabric shape such as an assembly of nanofiber nonwoven fabric (composite) (Patent Document 5) formed by simultaneously electrospinning an elastomer component, a hydrophilic component, and an adhesive component. There are examples of application studies in the form of non-sheets such as filters and bandages that are used as they are, but none of them are intended to improve mechanical properties as bulk molded products. On the other hand, as an example of study on the sheet shape, a biodegradable polymer nanofiber made of a biosynthetic biodegradable polymer with a chemical composition with a controlled biodegradation rate was created to improve the biodegradation rate. (Patent Document 6), a composite material obtained by impregnating a resin nanofiber nonwoven fabric by electrospinning with a specific epoxy resin raw material and curing it (Patent Document 7) or an example of a composite with an unsaturated polyester resin ( Non-patent document 2). In the case of Patent Document 6, it is useful as an example studied for the purpose of improving the mechanical properties of plant-derived materials, and in the case of Non-Patent Document 2, the effect on improving the mechanical properties has been verified. No mention is made of the effects in the resin system. As examples of composites with non-organic nanofibers, examples of nanofibers made of metal oxide using a sol-gel method and a resin matrix have been reported. There is no mention of mechanical properties as a material for achieving compatibility. In this system, a silane coupling agent is also required for adhesion between the nanofiber and the resin matrix (Patent Document 8).

JP 2005-298790 A JP 2003-276102 A JP 2008-73938 A JP 2008-95266 A JP-T-2006-501373 JP 2008-223185 A JP 2007-302718 A JP 2008-179752 A

http://www.meti.go.jp/policy/recycle/main/data/research/h16fy/model16-3.html http://www.cit.nihon-u.ac.jp/kenkyu/kouennkai/reference/No_41/1_kikai/1-030.pdf

  In particular, resin fibers made of the same type of resin as the matrix resin are used in order to obtain various thermoplastic resin moldings that have improved mechanical properties in sheet-like and thin-walled moldings and are capable of level material recycling. It is an object of the present invention to provide a reinforced composite material.

  As a result of intensive investigations to achieve the above object, the present inventors have completed the invention shown below.

[1] A composite material composed of thermoplastic resin A and thermoplastic resin B resin fibers,
The thermoplastic resin A and the thermoplastic resin B are the same type of resin in their repeating molecular chain structure,
The resin fiber of the thermoplastic resin B has a higher processable temperature than the thermoplastic resin A,
The compounding ratio of the resin fibers of the thermoplastic resin B is 1 wt% or more, 50 wt% or less,
The thermoplastic resin A and the thermoplastic resin B do not contain a filler, so that a level material recycling is possible.

[2] The composite material according to [1], wherein the resin fiber is formed by electrospinning.

[3] The composite material according to [2], wherein the resin fiber is a nonwoven fabric formed by an electrospinning method.

[4] The thermoplastic resin A is positioned on both sides of the resin fiber, and the thermoplastic resin A is melted and composited at a temperature not lower than the processable temperature of the thermoplastic resin A and not higher than the processable temperature of the thermoplastic resin B. The composite material according to any one of [1] to [3], wherein
The processable temperature in the present invention is a temperature at which the temperature of the thermoplastic resin increases, fluidity appears, the viscosity as a fluid decreases, and processing with a molding machine becomes possible.

[5] A method for producing a composite material comprising a thermoplastic resin A and a resin fiber of a thermoplastic resin B having a higher processable temperature than the thermoplastic resin A, wherein the thermoplastic resin A of [1] And the resin fiber according to any one of [1] to [3], the thermoplastic resin A is positioned on both sides of the resin fiber, and the thermoplastic resin A has a processing temperature or higher, A method for producing a composite material, wherein the thermoplastic resin A is melted and compounded at a temperature lower than a processable temperature of the thermoplastic resin B.

[6] A composite material molded body obtained by molding the composite material according to [4] into a film, a sheet, or a plate.

[7] A composite material obtained by laminating the composite material molded body of [6] above and fusing at a temperature not lower than the processable temperature of the thermoplastic resin A and not higher than the processable temperature of the thermoplastic resin B. A laminate of molded bodies.

The composite material of the present invention can be formed of various thermoplastic resins due to its structure, and can be easily molded because the material is a thermoplastic resin.
Also, since the resin fiber and matrix (thermoplastic resin A) functioning as a reinforcing material are the same type of resin in the repeated molecular chain structure, adhesion between the resin fiber and the matrix is good without using a compatibilizer. Therefore, even when a large deformation is imparted by tensile deformation or the like, interface peeling hardly occurs, and it becomes possible to form a sheet-like molded product or a thin molded product that exhibits high strength.

  Then, by heating the composite material made of the same resin again to a temperature equal to or higher than the melting point of the resin fiber, it is possible to erase all the structure formed as the composite material and repletize it as a uniform resin material. .

  Furthermore, since the resin fiber produced by the electrospinning method can be made into a fiber having a smaller fiber diameter, when used in a composite material, the effect of increasing the matrix reinforcing effect by increasing the specific surface area of the fiber. Can be demonstrated. And when resin-made fiber is made into a nonwoven fabric by the electrospinning method, since a fiber becomes a long fiber, it becomes possible to further improve the breaking strength of a composite material.

Electrospinning concept SEM image of nonwoven fabric made of PA6 nanofibers Appearance of composite sheet Cross-sectional SEM image of composite material

  An embodiment of the present invention will be described in detail as follows.

(Thermoplastic resin)
The thermoplastic resin used for the thermoplastic resin A and the thermoplastic resin B in the present invention is solid in the environment used as a product, and the processing temperature when molding these resins, specifically, the melting point or At a temperature above the softening point, it is a resin having fluidity like a liquid.

  Specifically, polystyrene, polyethylene, ultra high molecular weight polyethylene, polypropylene, α-olefin copolymer, polybutene-1, polymethylpentene, cyclic olefin polymer, ethylene / vinyl acetate copolymer (EVA), ethylene-methacrylic acid copolymer Polymer (EMAA), ionomer, modified polyolefin, polyvinyl chloride, vinylidene chloride resin, ABS resin, AS resin, MBS resin, polystyrene, methacrylic resin, polyvinyl alcohol, EVOH resin. Styrenic block copolymer resin, polyamide resin, polyacetal resin, polycarbonate, modified polyphenylene ether, thermoplastic polyester resin, fluororesin, polyphenylene sulfide, polysulfone, amorphous polyarylate, polyether imide, polyether sulfone, polyether ketones, liquid crystal Polymer, Polyamideimide, Thermoplastic polyimides, Syndio-type polystyrene, Styrenic thermoplastic elastomer contained in thermoplastic elastomer, Polyolefin thermoplastic elastomer, Polyvinyl chloride thermoplastic elastomer, Polyurethane thermoplastic elastomer, Polyester thermoplastic Poly-3-hydroxybuty contained in elastomer, 1,2-polybutadiene thermoplastic elastomer, biodegradable plastic , Polylactic acid, polycaprolactone, polybutylene succinate, poly (butylene succinate / adipate), polyethylene succinate, poly (butylene succinate / carbonate), poly (butylene adipate / terephthalate), poly (ethylene succinate / Terephthalate), poly (butylene succinate / adipate / terephthalate) polyvinyl alcohol, copolymers thereof and alloy materials containing them.

  The plurality of thermoplastic resins constituting the composite material of the present invention are required to belong to the same type in the structure of the repeating unit constituting the molecular chain.

  The same type means that the repeating unit contains characteristic chemical bonds in common, and strong intermolecular interactions such as hydrogen bonding interactions, electrostatic interactions, van der Waals interactions. It means having a characteristic group having an action, p / p stacking, coordination bond, charge transfer interaction, hydrophobic interaction and the like.

  For example, in the case of a polyamide resin having an amide bond, a molecular chain structure such as polyamide 6, polyamide 66, polyamide 11, polyamide 12, polyamide MXD-6, polyamide 610 or polyamide 6/66 or polyamide 6/12 which is a copolymerized polyamide This corresponds to a group of resins that are understood to exhibit similar physicochemical properties by containing amide bonds in common. In the case of the above-mentioned polyamide, products that have already been industrially produced in large quantities are listed, but this is not necessarily limited to this, and there is no problem as long as the resin has an amide bond as a repeating unit in the molecular chain. The same applies to other thermoplastic resins.

  Further, in the case of a resin that is difficult to find a special chemical bond in a repeating unit such as a polyolefin resin, the same type of resin is a resin that does not have such a characteristic group in the repeating unit.

  Next, in the case where the thermoplastic resin is a copolymer, the same type is a monomer type having a chemical bond having the above-mentioned characteristic group in the chemical structure of a plurality of monomer types constituting the copolymer. Resins having a common chemical bond having a characteristic group are of the same type. Even if the molar component ratio of the monomer species having a chemical bond with the characteristic group contained in the copolymer composition is small due to the energy of intermolecular interaction, potential position dependence, direction dependence and medium dependence, In some cases, it may be regarded as a resin.

  In addition, when the thermoplastic resin is a polymer alloy composed of a plurality of resins, in the composition having an alloy structure composed of a sea-island structure, the resins having the same chemical bond having a characteristic group contained in the resin that becomes the sea phase are of the same type. It becomes. On the other hand, when a co-continuous phase structure is formed, a resin having a chemical bond having the characteristic group included in the polymer alloy in consideration of the energy of intermolecular interaction, potential position dependency, and direction dependency. It is necessary to determine which of the species is a resin representative of the thermoplastic resin.

  Finally, when the polymer alloy is completely compatible under the conditions of use, a chemical bond having a characteristic group contained in the resin that has the largest volume fraction among the resin species constituting the polymer alloy is commonly used. The resins they have are of the same type.

  Generally, in order to form a resin composite material, it is essential to ensure the adhesiveness of the constituent component interface. The composite material of the present invention can be regarded as a polymer alloy composed of thermoplastic resins A and B rather than in terms of its structure.

  In this case, a compatibilizing agent is required for chemical bonding between the resins. However, since the composite material of the present invention is the same in terms of chemical structure, no special compatibilizing agent is required. Therefore, there are no components other than the thermoplastic resins A and B that can be called adhesive layers at the interface. Since it is the same kind of material, the formation of the interface is unlikely to occur, and the composite effect is maximized. Moreover, the complicated process of appropriate dispersion | distribution and a process of a compatibilizing agent is unnecessary, and the problem derived from selection of a compatibilizing agent, its usage, etc. does not generate | occur | produce.

  The molecular weight of such a thermoplastic resin is not particularly limited, but it is desirable that the molecular weight be at least enough to stabilize the performance as a resin material. In the case of a molecular weight of the order of an oligomer, the toughness as a material is not expressed, and it is not preferable because it is thermally unstable.

  In addition, since the thermoplastic resin does not contain any shape (spherical, plate-like, fiber-like, needle-like filler, these fillers are solid or tube-like hollow), and the composition filler, Level material recycling is possible. The filler here means a compound that is blended in a large amount for the purpose of improving the mechanical properties, heat resistance and dimensional stability of the composite material, and imparting other functions (flame retardancy, conductivity, magnetism, heat, etc.). Conductivity, piezoelectricity, vibration control, sound insulation, sliding control, interstitial material, anti-blocking, heat insulation, light weight, electromagnetic wave absorption, light scattering, ultraviolet absorption, radiation absorption, infrared radiation, mine / disinfectant, dehydrating agent , Adsorbent, high specific gravity, gas barrier).

  Resin material recycling technology is broadly divided into three types: material recycling, chemical recycling, and thermal recycling. There are also level material recycling and cascade material recycling in the material recycling classification. Among the recycling methods, the level material recycling is the simplest process that requires less energy and requires less energy. After processing waste plastic waste, such as crushing and dissolution, it can be used for similar purposes. Indicates recycling as a material. A normal composite material contains an inorganic material as a reinforcing material. However, since the filler is physically destroyed in the recycling process, the performance is remarkably deteriorated and cannot be used for level material recycling. On the other hand, the composite material of the present invention can be used again as a matrix resin by being melted and integrated by placing it above the melting point of the resin fiber.

(Resin fiber)
The resin fiber in the present invention refers to a fibrous molded body produced using the above-described thermoplastic resin.

  The above-mentioned thermoplastic resin is generally understood by distinguishing between a crystalline resin and an amorphous resin, but in the present invention, at least one of the thermoplastic resins constituting the composite material is a crystalline polymer. It is desirable that the thermoplastic resin constituting the resin fiber is particularly a crystalline resin.

  The crystallinity of crystalline polymers is not necessarily high, and the value varies depending on the measurement method, but some of the crystal parts contained in the resin are physical properties as a resin material. It has a great influence on it. Even with a slight difference in crystallinity, there are many resins that change greatly, such as heat resistance and impact resistance, and conversely, desired performance is often imparted by adjusting the crystallinity. In the present application, when used as the thermoplastic resin B, it is desirable to use a resin having a high crystallinity or a high crystallinity. Further, since the processing temperature varies even with the same material by changing the crystallinity, the composite material of the present invention can be composed of one kind of thermoplastic resin in some cases.

  In order to adjust the crystallinity, it is generally preferable to perform heat treatment for a certain period of time at a temperature equal to or higher than the glass transition temperature of the resin. However, if the resin is hygroscopic, hydrothermal treatment is also an effective means. . The crystallinity adjustment mentioned here includes not only changing the ratio of crystal / amorphous, but also changing the density of crystal parts accompanying rearrangement of polymer chains constituting the crystal.

  The size of the resin fiber is preferably 10 nm or more and preferably 5000 nm or less as an average diameter. When it is smaller than 10 nm, it is not preferable because impregnation of the thermoplastic resin into the fiber becomes difficult during the production of the composite material molded body described later. On the other hand, if it is larger than 5000 nm, there is a tendency that the effect of improving the material properties accompanying compounding tends to be poor, and in addition, it is also known as a composite material because it is also a fiber diameter that can be sufficiently prepared by ordinary melt spinning. is there.

  The length of the resin fiber is not particularly limited. That is, the produced fibrous molded body may be used as it is without being cut, but it is preferable. In the present invention, it is desirable to use a non-woven resin fiber obtained by an electrospinning method described later as it is. Because the obtained nonwoven fabric is made of continuous fibers, and when it is deformed to pull the nonwoven fabric sheet, it is difficult to break due to the entanglement of the fibers, which improves the strength and toughness of the composite material. This is because there is an effect.

  The electrospinning method is preferably used for the production of the resin fibers. As shown in FIG. 1, the electrospinning method is a method of obtaining a non-woven fibrous shaped article by injecting a resin solution between a syringe needle to which a high voltage is applied and a collector. This is characterized in that the diameter of the resin fiber obtained is smaller than that of the fibrous molded body obtained by a known nonwoven fabric production method, and the obtained resin fiber is called nanofiber. Factors affecting the shape of the resulting resin fiber in the electrospinning method include the resin type, molecular weight, solvent type, resin solution concentration, resin solution injection speed (discharge volume per hour), and syringe needle. Diameter, distance between the tip of the syringe needle and the collector, applied voltage, and how to ground the collector. In obtaining the resin fiber of the present invention, there is no particular restriction on the above-mentioned factors, but it is essential to obtain the resin fiber having the above-mentioned average particle diameter by optimizing these factors.

(Production method of composite material)
The production of the composite material of the present invention has the following characteristics. The higher processable temperature of the thermoplastic resin constituting the composite material, that is, the processable temperature (T) obtained as a result of intentional modification by applying a melting point or heat treatment generally obtained as a resin characteristic when compounding a resin made of a fiber and the thermoplastic resin a (processable temperature T _a ° C.) of thermoplastic resin B having a _B ° C.), the production temperature (T _P ° C.) as T _a <T _P < T _B is required. When _TP is lower than T _{A, the} molding itself is not realized because it is lower than the processable temperature of the thermoplastic resin constituting the composite material. If T _P is higher than T _B in the other hand, it does not hold the composite form of the present invention for resin fibers is melted. In such a temperature range, the resin fiber is impregnated with the thermoplastic resin A, and both are physically integrated. At this time, there is no restriction on the production method other than the temperature factor, but it is desirable to melt and mix the resin fiber and the thermoplastic resin in order to form a kind of interfacial adhesive layer corresponding to the compatibilizer described above. Is also possible. In that case, it is preferable to optimize the pressure applied at the time of contact between the two.

  The composite material of the present invention is characterized in that resin fibers made of a thermoplastic resin B are sandwiched from both sides by a resin layer made of a thermoplastic resin A. By forming such a sandwich structure under the molding temperature conditions described above, the resin fiber layer is sufficiently melt impregnated with the thermoplastic resin A, and the thermoplastic resins A and B are sufficiently combined and combined. A material compact is obtained. Furthermore, by laminating this composite material laminate, the material properties can be designed and adjusted in various ways.

  In order to obtain a composite material molded body or a laminate thereof according to the present invention, various manufacturing methods can be applied as long as the molding temperature condition is satisfied. Compression molding, extrusion molding (multi-layer extrusion), injection molding (insert molding) It can be handled by general hot melt processing such as. In addition, there are no restrictions on the thickness of the resin fiber layer and the thermoplastic resin layer, the number of laminations, and the like for the composite. What is necessary is just to use the optimal structure for obtaining the required material physical property.

  In the composite material of the present invention, the amount of the resin fiber layer is preferably 1 wt% or more and 50 wt% or less, and more preferably 5 wt% or more and 30 wt% or less, as long as both physical properties of the material and material recycling are achieved. When the compounding amount of the resin fiber layer is less than 1 wt%, the effect of improving the physical properties by using a composite material is poor. On the other hand, when the amount of resin fibers exceeds 50 wt%, it is difficult to form a state in which the fiber surface is well wetted by the matrix resin in the compounding method using the difference in melting point as in the present invention. Since the interfacial adhesive strength is lowered, it is not preferable in terms of physical properties of the composite material.

  Furthermore, the composite material of the present invention includes a heat stabilizer, a light stabilizer, an antioxidant, a plasticizer, an impact modifier, an antistatic agent, a release agent, and various processing aids as long as the physical properties of the material are not impaired. An agent may be included.

  Since the composite material of the present invention can improve the mechanical properties, heat resistance, and barrier properties of a thin molded product, it can be applied to tube and film applications. Specific examples include catheters, wound dressings, beverage bottles and packaging films. In addition, when a thicker molded product can be obtained by application such as insert molding, it can be applied to various electrical appliance casings, automobile exterior materials, and the like.

  The present invention will be specifically described below with reference to examples and comparative examples. However, the present invention is not limited to the examples.

<Production of resin fiber>
Pellets of polyamide 6 resin (indicated as PA6, melting point: 220 ° C., Unitika A1030BRL) were dried with hot air at 80 ° C. for 8 hours, and then prepared to be a 20 wt% formic acid solution. Electrospinning was performed by placing a separately prepared polyamide 12 (indicated as PA12, melting point: 176 ° C., Rilsan AESN O-TL manufactured by Arkema) (thickness: 100 μm) on an aluminum collector. Specifically, the conditions were an applied voltage of 20 to 22 kV, a syringe needle with a diameter of 25 G, an injection speed of 3 ml / h, and a syringe-collector distance of 8 cm. The SEM observation image of the produced nonwoven fabric made of polyamide resin fibers is shown in FIG. 2 (in the case of polyamide 6: expressed as PA6 nanofiber). The diameter of the obtained non-woven fiber was about 100 to 400 nm, and it was found that the non-woven fiber was made of even finer nanofibers even by an existing non-woven fabric manufacturing method.

<Manufacture of composite materials>
A PA12 film (thickness: 100 μm) was further placed on the PA6 nanofiber produced on the PA12 film, and the whole was pressure-bonded at a processing temperature of 200 ° C. using a vacuum press. Thereafter, the obtained composite material sheet was cooled at 80 ° C. and collected. FIG. 3 shows the appearance of the composite material sheet cut out into a dumbbell shape after the pressure bonding. In SEM observation, it was found that when PA12 was sufficiently melt impregnated into the PA6 nanofiber nonwoven fabric layer (FIG. 4), the molded product was not whitened and a homogeneous sheet was obtained by visual observation.

(Performance evaluation of molded products)
<Confirmation of composition of composite material sheet>
The cross section obtained by dividing the obtained composite material sheet in a state immersed in liquefied nitrogen was observed with FE-SEM, and the thicknesses of the PA12 layer and PA6 nanofiber layer in the SEM image were read.

<Tensile measurement>
A composite material sheet having a thickness of about 200 μm was cut into a small dumbbell shape and subjected to a tensile test at a speed of 100 mm / min.

<Recycling test>
Once formed, the composite material sheet was chopped, put into a twin-screw kneader set at 240 ° C., collected as a strand, and pelletized. The obtained pellet was pressed under reduced pressure at 240 ° C. to prepare a sheet (thickness: 200 μm) made of a recycled material, and tensile measurement was performed again according to the above procedure. Evaluation of recyclability calculated the ratio of the tensile strength of the sheet | seat which consists of recycled materials, and the tensile strength of the thermoplastic resin A independent which comprises a composite material. That is, [tensile strength of recycled resin] / [tensile strength of thermoplastic resin A alone] (%) was calculated. If this value is smaller or larger than 100%, it means that the physical properties of the thermoplastic resin A are greatly lowered during recycling.

[Example 1]
A composite material sheet having a structure in which PA6 nanofibers are sandwiched between PA12 layers from above and below was produced by the above-described method, and the composition of the composite material sheet was confirmed and subjected to tensile measurement and a recycling test. From the change in weight during the formation of PA6 nanofibers, the blended amount of PA6 fibers in the finally obtained composite material was 4.8 wt%.

[Example 2]
Example 1 was followed except that the blended amount of PA6 fiber in the finally obtained composite material was 25 wt%.

[Comparative Example 1]
A PA12 sheet molded according to the thickness of the composite sheet was prepared and subjected to tensile measurement and a recycling test.

[Comparative Example 2]
A composite material sheet having a structure in which a PA6 film (not electrospun) is sandwiched between upper and lower layers by a PA12 layer was prepared by the above-described method, and subjected to composition confirmation, tensile measurement, and a recycling test of the composite material sheet. The weight percentage of the PA6 sheet was 5.7 wt%.

[Comparative Example 3]
Comparative Example 2 was followed except that the blend amount of the PA6 sheet in the finally obtained composite material was 22 wt%.
[Comparative Example 4]
A composite material was obtained according to Example 1 except that the blending amount of PA6 fiber in the finally obtained composite material was 0.8 wt%.
[Comparative Example 5]
A glass-reinforced polyamide 12 (Rilsan AZM30 O T6LD manufactured by Arkema) is mixed with a predetermined amount of PA12 pellets and then melt-kneaded (kneading temperature 240 ° C) to create a resin composition equivalent to a 5% glass fiber reinforced product. (Noted as PA12G5). A composite material of this material and PA6 fiber was prepared according to Example 1. The blending amount of PA6 fiber in the finally obtained composite material was 21 wt%.

  The composition and evaluation results of the composite material sheets obtained in Examples 1 and 2 and Comparative Examples 1 to 5 are collectively shown in Table 1.

  From Table 1, Example 1 shows a large elongation at break of 305% while having a large initial elastic modulus exceeding PA12 (Comparative Example 1), indicating that PA12 could be improved without using a compatibilizer or the like. On the other hand, there is almost no change in physical properties during recycling, and it can be used for level material recycling. In addition, when the amount of PA6 is large (Example 2), the numerical value is higher than the performance of PA12 (Comparative Example 1) because it causes a large change in material properties and the performance of PA6 becomes obvious during recycling. . In the case of this Example 2, since the ratio of PA6 added as a nanofiber layer was higher than that in Example 1, the recyclability defined above showed a high value. In this case, PA12 It is also possible to use as a heat fusion resin as a material close to PA12 by mixing and diluting with recycled material.

  On the other hand, since no significant elongation was observed in Comparative Examples 2 and 3, it was found that the composite effect could not be obtained unless a compatibilizing agent (adhesive layer) was appropriately provided in the simple sheet pressure bonding. Further, only the PA12 raw material sheet of Comparative Example 1 was measured for elastic modulus and elongation according to known material properties, and was judged to be a value that could be sufficiently employed as a Comparative Example. Comparative Example 4 is a case where the blending amount of PA6 fiber is too small, and the recyclability is excellent, but the performance improvement as a composite material was not recognized. Lastly, in Comparative Example 5, which is a glass-reinforced composite material, the glass fiber breakage frequently occurs during recycling in addition to the fact that the elongation at break is small and the tendency to be hard and brittle is increased. It was found that the performance degradation was significant and it was not suitable for level material recycling.

[Comparative Example 6]
Except that the blended amount of PA6 fiber in the finally obtained composite material was 54 wt%, an attempt was made to create a composite material according to Example 1, but the fiber surface was satisfactorily wet with the matrix resin. It was difficult to form a state, and as a result, only a composite material having a weak interfacial adhesive strength was obtained.

The thermoplastic resin composite material of the present invention can be obtained by superimposing the properties of the constituent resin with a simple composition without using a compatibilizer according to the polymer alloy by optimally selecting the combination of raw material resins constituting the thermoplastic resin composite material. It is possible to form a composite material having excellent material characteristics and excellent material recyclability.
Since the composite material of the present invention can improve the mechanical properties, heat resistance, and barrier properties of a thin molded product, it can be applied to tube and film applications. Specific examples include catheters, wound dressings, beverage bottles and packaging films. In addition, when a thicker molded product can be obtained by application such as insert molding, it can be applied to various electrical appliance casings, automobile exterior materials, and the like.

Claims (7)

A composite material composed of thermoplastic resin A and thermoplastic resin B resin fibers,
The thermoplastic resin A and the thermoplastic resin B are the same type of resin in their repeating molecular chain structure,
The resin fiber of the thermoplastic resin B has a higher processable temperature than the thermoplastic resin A,
The compounding ratio of the resin fibers of the thermoplastic resin B is 1 wt% or more, 50 wt% or less,
The thermoplastic resin A and the thermoplastic resin B do not contain a filler, so that a level material recycling is possible. The composite material according to claim 1, wherein the resin fiber is formed by an electrospinning method. The composite material according to claim 2, wherein the resin fiber is a nonwoven fabric formed by an electrospinning method. The thermoplastic resin A is positioned on both sides of the resin fiber, and the thermoplastic resin A is melted and compounded at a temperature not lower than the processable temperature of the thermoplastic resin A and not higher than the processable temperature of the thermoplastic resin B. The composite material according to claim 1, wherein: A method for producing a composite material comprising a thermoplastic resin A and a resin fiber of a thermoplastic resin B having a higher processable temperature than the thermoplastic resin A, wherein the thermoplastic resin A according to claim 1 and the claim are used. Item 4. The resinous fiber according to any one of Items 1 to 3, wherein the thermoplastic resin A is positioned on both sides of the resinous fiber, and the thermoplastic resin is at or above a processable temperature of the thermoplastic resin A. A method for producing a composite material, wherein the thermoplastic resin A is melted and composited at a temperature equal to or lower than the processable temperature of B. A composite material molded body, wherein the composite material according to claim 4 is formed into a film, a sheet, or a plate. A composite material molded body obtained by laminating the composite material molded body according to claim 6 and fusing at a temperature not lower than the processable temperature of the thermoplastic resin A and not higher than the processable temperature of the thermoplastic resin B. Laminated body.