JP2003277530A - Composite material and its production method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a thermoplastic resin fiber reinforced composite material having a high fiber content and a good impregnation state of a resin by a simple step. <P>SOLUTION: The thermoplastic resin fiber reinforced composite material is obtained by coating a monomer and/or an oligomer of a thermoplastic resin on the surfaces of high strength and high modulus organic fibers, and then polymerizing the monomer and/or the oligomer to effect integration. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fiber-reinforced thermoplastic resin composite material suitable for a wide range of industrial materials such as automobiles, aviation, construction, civil engineering and safety products.

[0002]

2. Description of the Related Art A conventional fiber-reinforced thermoplastic resin composite material (hereinafter referred to as FRTP) is roughly as follows. The injection molded product contained glass fiber, carbon fiber in olefin resin such as polypropylene, polyester resin such as polyethylene terephthalate, polyamide resin such as polyamide 6 in an amount of about 15 to 30 vol% in a short reinforcing fiber having a fiber length of 10 mm or less. The resin pellets are melted and discharged and flowed at a high speed to be molded. A discharge compression-molded product is obtained by melting and extruding the resin pellets, like an injection-molded product, and putting the product into a mold or the like, and compressing the resin pellets to cause them to flow at a relatively high speed. Since the above two molded products have fast resin flow, they can cope with complicated shapes and are widely used for general products. However, in order not to impair its fluidity, the reinforcing fiber has a fiber length of about 10 mm and a fiber content of 30 vol%.
There are limits and extents, and problems remain in mechanical properties such as strength and elastic modulus. In order to avoid this, there is a method in which a mold having a constant temperature is heated to a high temperature at the time of molding and a mold is taken out at a low temperature. However, temperature control is difficult, and the molding cycle becomes long, so that the yield is very poor. The stamping molded product is a swirl mat in which the above-mentioned reinforcing fibers having a fiber length of about 25 to 50 mm are accumulated and chopped mats bonded with a binder or the like or continuous reinforcing fibers are randomly accumulated in a plane and bonded with a binder or the like. The film-like resin is laminated alternately on the resin, heated and melted, and a molding material called a stampable sheet that has been integrated to a certain extent is put into the mold by melting the resin with a far infrared heater or the like, It is obtained by flowing the reinforcing fiber and the resin under high pressure.

This molded product is not suitable for a complicated shape because it is more difficult to flow than the injection molded product and the discharge compression molded product described above, but since the fiber length can be increased, mechanical properties such as strength and elastic modulus are improved. It However, since it is premised that the fiber is made to flow, the fiber content is limited to about 30 vol%. Filament winding molded products are made by continuously adhering a thermoplastic resin to continuous reinforcing fibers, winding a molding material such as mixed fiber while winding it around a cylindrical object called a mandrel, and pressing the molding material in the radial direction of the mandrel as necessary. It is obtained by integrating them. The compression molded product is the above-mentioned stampable sheet or woven or knitted fabric of reinforcing fibers, laminated with a thermoplastic resin film, powder is attached, or fibrous material is used to heat the molding material such as mixed fiber or mixed weave. It is obtained by charging the resin in a mold, melting the resin while applying compression, and then cooling and solidifying the resin. The above two molded products have little resin flow, so it is difficult to handle complicated shapes.
It is suitable for simple flat plates and the like, continuous reinforcing fibers can be applied, and since the fiber content can be close to 60 vol%, it has excellent mechanical properties such as strength and elastic modulus. However, since the melt viscosity of the thermoplastic resin is basically high, it was difficult to achieve a higher fiber content.

In addition to the above-mentioned molding method, Japanese Laid-Open Patent Publication No. 11-510
Japanese Laid-Open Patent Publication No. 863 discloses that an olefin resin, which is considered to be non-polar, is swollen with a solvent and a resin of the same system is entangled therein to improve the adhesiveness. Thus, it is possible to mold FRTP having a high fiber content by infiltrating the resin with a solvent, but the process is complicated and the solvent needs to be recovered, which is substantially difficult. In the case of a fiber-reinforced thermosetting resin composite material (referred to as FRTS) with respect to these FRTPs, the resin is dipped in the reinforced fiber in an uncured state having a low viscosity, so that a molded product having a high fiber content can be obtained. . However, the thermosetting resin is inferior in versatility since secondary molding is impossible after the curing reaction is completed. Moreover, since it is difficult to incinerate and dispose of it, in recent years, it tends to be avoided even in normal use.

[0005]

As described above, the conventional F
RTP is more environmentally friendly than FRTS, and molded products are sent to various fields by various molding methods, but basically thermoplastic resins have high melt viscosity, so it is necessary to include reinforcing fibers. It was difficult to obtain a molded product having a high fiber content.

[0006]

As a result of further studies made by the present inventor, an FRT having a high fiber content in a simple process is obtained.
I found P. That is, the present invention has the following configurations. 1. A composite material characterized by being integrated with the fiber by polymerizing a monomer and / or oligomer of a thermoplastic resin on the surface of the fiber. 2. The composite material according to the first aspect, wherein the volume content of the fibers is 60 vf% or more. 3. 3. The composite material according to the above 1 or 2, wherein the fiber is an organic fiber having high strength and high elastic modulus. 4. A method for producing a composite material, which comprises applying a thermoplastic resin monomer and / or oligomer to a fiber surface, and then polymerizing the same.

The fiber of the present invention is a reinforcing fiber applicable to FRTP, and it is necessary to select a fiber which does not decompose at the melting point or softening point of the thermoplastic resin or at the polymerization temperature or higher. The fibers to be applied include natural fibers such as palm fibers, polynosic fibers such as rayon, metal fibers such as tyranno fibers, glass fibers, basalt fibers, and inorganic fibers such as carbon fibers, but they are required as composite materials. 15cN / dt from the viewpoint of high strength and high elastic modulus
strength of ex or more, elastic modulus of 400 cN / dtex or more,
Furthermore, strength of 20 cN / dtex or more, 500 cN / d
A fiber having an elastic modulus of tex or more is desirable. Further, from the viewpoint of light weight, and from the viewpoint of environmental compatibility, polyethylene terephthalate resin, polypropylene resin, an organic material using a polypropylene resin or the like is preferable, when more lightweight is desired, a polyolefin-based fiber is preferable, and more preferably, High molecular weight polyethylene fibers may be mentioned. If heat resistance, impact resistance, chemical resistance, etc. are required, polyparaphenylene terephthalamide (para-aramid) fiber, polyetherimide fiber, polyphenylene sulfide fiber, polyether ether ketone fiber, etc. can be selected. Polybenzazole fibers such as the developed polyparaphenylenebenzobisthiazole and polyparaphenylenebenzobisoxazole can be applied. Further, for newly developed fibers in the future, for example, a silicon-based polymer material can be applied to the present invention.

To obtain the FRTP of the present invention, it is necessary to coat the fiber with a monomer and / or oligomer of a thermoplastic resin on the surface of the fiber and then polymerize the same. In the case of a solid, there are means such as coating by dissolving it in a solvent or the like, supporting it on a reinforcing fiber by using a binder, or wrapping the fiber with a film after coating the fiber. It is preferable to use a general liquid monomer or oligomer, and it is preferable that it has high fluidity like water at room temperature. The monomer described here is a monomer composed of a single molecule, that is, a monomer, and the oligomer means a polymer having a low degree of polymerization of a dimer or more. The monomers and oligomers are generic terms for a unit substance that produces a polymer by an addition reaction. Among them, the ones that produce the thermoplastic resin described above include butadiene, styrene, acrylonitrile, ethylene, and chloride. Vinyl etc. can be illustrated. In addition, ε-caprolactam and ω-aminocaproic acid are nylon-6, ω-
Hexamethylenediamine and adipic acid are nylon 66,
Methyl methacrylate can be exemplified as that of polymethylmethacrylate. Monomer or oligomer,
Also, the polymerization initiator and the catalyst are appropriately selected according to the thermoplastic resin shown above, but when the monomer or the oligomer volatilizes during the polymerization, the equipment is closed system, the pressure is reduced, etc. Therefore, it is necessary to take measures to avoid the diffusion to the surroundings. Alternatively, it is important to select a high molecular weight monomer or oligomer to avoid volatilization.

Further, it is important to design the product by paying attention to side reaction products in the polymerization reaction when selecting the thermoplastic resin in advance. In addition, polymerization is carried out while impregnating the reinforcing fiber with a mixture of a monomer or an oligomer, a polymerization initiator, and a catalyst, or at a temperature not lower than the reaction initiation temperature after impregnation. In this case, note the reaction rate. Therefore, it is important to determine the molding conditions.

The thermoplastic resin applied to the present invention is nylon 6 or nylon 6 which is generally called crystalline thermoplastic resin.
Examples thereof include polyamide resins represented by 6, polyethylene terephthalate, polyester resins represented by polybutylene terephthalate, polyolefin resins represented by polyethylene and polypropylene, and syndiotactic polystyrene and polyacetal. In addition, polyphenylene sulfide having high heat resistance, polyether ether ketone, liquid crystalline polymer, fluororesin, polyether nitrile and the like can be mentioned. Polyester elastomer obtained by block-copolymerizing the above-mentioned crystalline thermoplastic resin with a soft segment having a molecular weight of 300 to 5,000 such as polyether glycol, polyester glycol and polycarbonate glycol. -, Polyamide elastomers, polyurethane elastomers and other thermoplastic elastic resins are also included.

In addition, examples include polycarbonate, which is generally called amorphous thermoplastic resin, modified polyphenylene ether, polysulfone having high heat resistance, polyether sulfone, polyarylate, polyamideimide, polyetherimide, and thermoplastic polyimide. In addition,
The present invention is suitable for these amorphous thermoplastic resins which are generally said to have a problem in fluidity. It is necessary to select the combination of the reinforcing fiber and the thermoplastic resin according to the purpose, but it is important to select a thermoplastic resin similar to the reinforcing fiber in order to improve the adhesive performance between the reinforcing fiber and the resin and the separation and disposal after use. It is suitable in terms of

[0012]

EXAMPLES Examples of the present invention, and in the text below,
And the evaluation method in the examples will be described. (1) Fiber content rate and void rate of composite material JIS K 7075 "Test method for fiber content rate and void rate of carbon fiber reinforced plastic" and JIS K
7052 "Method for measuring fiber content of glass fiber reinforced plastic", the fiber (volume) content was determined from the fiber supply amount and the FRTP weight ratio and the density. (2) Impregnated state An arbitrarily selected cross section is observed by an optical microscope or the like, and the content of the reinforcing fiber in a state where 50% or more of the peripheral length is in contact with the resin is shown. Here, 70% or more is good, 70 Those less than% were regarded as defective. (Examples 1 to 4) A high molecular weight polyethylene fiber ("Dyneema: SK60" manufactured by Toyobo Co., Ltd.) was wound around a tetrafluoroethylene frame in one direction, and this was used as a monomer, methyl methacrylate, and a reaction initiator α, α'-azobis-isobutylnitrile (6 wph) in a glass container (about 20
After immersing in the mixture at 0 ° C.), it was laid in a flat mold coated with tetrafluoroethylene. After placing a spacer with a thickness of 2 mm, sandwiching it with a flat plate mold coated with tetrafluoroethylene, and sealing the periphery with a quick-drying sealant,
The mixture was heated and compressed on a press molding machine (heating plate temperature 65 ° C.) to polymerize the mixture. In addition, it carried out in the form as shown in FIG. 1 and changed the number of winding of this fiber, and obtained the composite material of Examples 1-4.

(Comparative Examples 1 to 4) High molecular weight polyethylene fibers ("Dyneema: SK60" manufactured by Toyobo Co., Ltd.) were sufficiently opened with an opening bar, and then tetrafluoroethylene was used in the same manner as in Examples 1 to 4. Wrapped around the frame in one direction.
At that time, methyl methacrylate as a monomer and α, α′-azobis-isobutylnitrile (6 wph) as a reaction initiator were used in a glass container (about 20%) as in Examples 1 to 4.
After mixing at 65 ° C. and polymerizing at 65 ° C., the powdered product was applied between the fibers and laid on a flat mold coated with tetrafluoroethylene. Furthermore, a spacer with a thickness of 2 mm is placed, sandwiched between flat plate molds coated with tetrafluoroethylene, and the periphery is sealed with a quick-drying sealant, which is then heated and compressed on a press molding machine (heating plate temperature 110 ° C.) for comparison. Examples 1-4
A composite material of

[0014]

[Table 1]

(Examples 5 to 8) A cloth (plain weave: 15 wefts / 2.54 cm) made of high molecular weight polyethylene fibers ("Dyneema: SK60" manufactured by Toyobo Co., Ltd.) was used in Example 1
~ 4, after dipping in the same mixture (methyl methacrylate as a monomer, α, α'-azobis-isobutylnitrile (6 wph) as a reaction initiator, mixed in a container (about 20 ° C)), tetrafluoro It was laid on a flat mold coated with ethylene. Further, a spacer having a thickness of 2 mm is placed, sandwiched between flat plate molds coated with tetrafluoroethylene, and the periphery is sealed with a quick-drying sealant, and then heated and compressed on a press molding machine (heating plate temperature 65 ° C.), The mixture was polymerized. In addition, by changing the number of laminated layers of the cloth,
A composite material of 8 was obtained.

(Comparative Examples 5-8) As in Examples 5-8, a cloth (plain weave: 15 wefts / two wefts) made of high molecular weight polyethylene fibers ("Dyneema: SK60" manufactured by Toyobo Co., Ltd.).
Polymers similar to Comparative Examples 1 to 4 (54 cm) (methyl methacrylate and α, α′-azobis-isobutylnitrile (6 w
ph) was mixed, and the powder of (polymerization at 65 ° C.) was applied, and the powder was laid on a flat mold coated with tetrafluoroethylene. Furthermore, a spacer with a thickness of 2 mm is placed, sandwiched between flat plate molds coated with tetrafluoroethylene, and the periphery is sealed with a quick-drying sealant, which is then heated and compressed on a press molding machine (heating plate temperature 110 ° C.) for comparison. The composite materials of Examples 5-8 were obtained.

[0017]

[Table 2]

(Example 9) A laminate of fabrics (plain weave: 30 wefts / 2.54 cm) made of polybenzol fiber ("Zylon: AS" manufactured by Toyobo Co., Ltd.) was laminated.
Flat metal coated with tetrafluoroethylene on the same mixture as in Example 8 (methyl methacrylate as a monomer, α, α'-azobis-isobutylnitrile (6 wph) as a reaction initiator, mixed in a container (about 20 ° C)) Laid in a mold. Then, place a spacer with a thickness of 2 mm, sandwich it with a flat metal mold coated with the same tetrafluoroethylene, and seal the periphery with a quick-drying sealant, and then heat and compress it on a press molding machine (heating plate temperature 65 ° C). Then, the mixture was polymerized to obtain a composite material of Example 9.

(Comparative Example 9) In the same manner as in Example 9, a laminate of a fabric (plain weave: 30 wefts / 2.54 cm) made of polybenzol fiber ("Zylon" manufactured by Toyobo Co., Ltd.) was laminated. Powder of polymer (mixing methyl methacrylate and α, α′-azobis-isobutylnitrile (6 wph) and polymerizing at 65 ° C.) was applied in the same manner as in No. 8, and laid on a tetrafluoroethylene-coated flat plate mold. . 2m thick
m spacer was placed, the lid was covered with a flat plate mold coated with tetrafluoroethylene, and the periphery was sealed with a quick-drying sealant, followed by heating and compression on a press molding machine (heating plate temperature 110 ° C.). A composite material of 9 was obtained.

Example 10 A mixture of non-woven fabrics (fineness 14 dtex: basis weight 400 g / m ² ) made of polyester fibers (manufactured by Toyobo Co., Ltd.) was laminated in the same manner as in Example 9 (methyl methacrylate as a monomer). , Α, α'-azobis-isobutylnitrile (6wp as a reaction initiator)
h), after being dipped in a container (mixed in a container (about 20 ° C.)), it was laid in a flat mold coated with tetrafluoroethylene. Further, place a spacer with a thickness of 2 mm, cover with a similar tetrafluoroethylene-coated flat plate mold, and seal the periphery with a quick-drying sealant, then heat on a press molding machine (heating plate temperature 65 ° C). Pressed and polymerized the mixture to obtain the composite material of Example 10.

(Comparative Example 10) As in Example 10, a laminate of non-woven fabric (fineness 14 dtex: basis weight 400 g / m ² ) made of polyester fiber (manufactured by Toyobo Co., Ltd.) was laminated in the same manner as Comparative Examples 5-8. A powder of a polymer (methyl methacrylate and α, α′-azobis-isobutylnitrile (6 wph) were mixed and polymerized at 65 ° C.) was applied, and the powder was laid on a tetrafluoroethylene-coated flat plate mold. 2m thick
m spacer was placed, the lid was covered with a flat plate mold coated with tetrafluoroethylene, and the periphery was sealed with a quick-drying sealant, followed by heating and compression on a press molding machine (heating plate temperature 110 ° C.). Ten composite materials were obtained.

[0022]

[Table 3]

The materials, processing conditions, and evaluation results of Examples 1 to 10 and Comparative Examples 1 to 10 described above are shown in Tables 1 to 3. From Examples 1 to 4 and Comparative Examples 1 to 4 in Table 1, the composite materials of the present invention have a high fiber content, a good impregnation state, and a low void ratio. On the other hand, in the comparative example, it can be seen that as the fiber content increases, the impregnated state deteriorates and only those having a high void ratio can be obtained. From Examples 5 to 8 and Comparative Examples 5 to 8 in Table 2, the composite material of the present invention has a high fiber content even if the morphology of the fibers is changed, the impregnated state is good, and the void content is low. Has been. On the other hand, in the comparative example, it can be seen that as the fiber content increases, the impregnated state deteriorates and the void ratio decreases only as in the previous case. From Examples 9 to 10 and Comparative Examples 9 to 10 in Table 3, the composite material of the present invention has a high fiber content even if the material of the fiber is changed, the impregnation state is good, and the void content is low. Has been. On the other hand, in the comparative example, it can be seen that as the fiber content increases, the impregnated state deteriorates and only those having a high void ratio can be obtained in the same manner as above. Generally, in a composite material, continuity between fibers is required to obtain mechanical properties, and in order to satisfy this, it is important that the resin is impregnated in the fiber bundle. Regarding the impregnated state, when an arbitrarily selected cross section is observed with an optical microscope or the like, and when the content of the reinforcing fiber in a state where 50% or more of the fiber perimeter is in contact with the resin, 70% or more is preferable, and further, Is more preferably 80% or more,
As the fiber content increases, it becomes more difficult for resin to enter between the fibers, and the void ratio increases. However, the FRTP of the present invention has a high fiber content which makes it difficult to impregnate the resin, which is an effect of the present invention. And the porosity is small. From the above results, the composite material of the present invention, in which the monomer and / or oligomer of the thermoplastic resin is applied to the surface of the fiber and then polymerized to be integrated, has a high fiber content and yet has a high mechanical property. Since the impregnated state which influences is good and the void ratio is also low, it can be expected that the capabilities of the reinforcing fiber and the thermoplastic resin of the matrix can be maximized. In the case of unidirectional fiber reinforced type, such FTRP is used as a reinforcing material for reinforcing optical fibers and wire harnesses, such as ropes used in the ocean and lakes, materials such as bicycle spokes and tennis gut, wire materials for geotextile, It can be applied to the line of leisure sports equipment such as yachts, canoes and gliders. Also,
In the case of a two-dimensional reinforced type such as a cloth, it is possible to apply it to various fields such as an impact resistant material and a vibration damping material by utilizing the characteristics of the reinforced fiber. Further, by applying the molding method of the present invention, as long as the morphology of the fiber and the limitation of the mold release allow.
It is possible to correspond to various shapes.

[0024]

EFFECTS OF THE INVENTION According to the present invention, a thermoplastic resin fiber reinforced, which has a high fiber content and a good resin impregnation state, is suitable for a wide range of industrial materials such as automobiles, aviation, construction, civil engineering, and safety products by a simple process. It was possible to obtain a composite material.

[Brief description of drawings]

FIG. 1 is a schematic view showing one form of an embodiment applied to the present invention.

[Explanation of symbols]

1: Tetrafluoroethylene frame, 2: Tetrafluoroethylene coated flat plate mold, 3: Fiber

Front page continuation (51) Int.Cl. ⁷ Identification code FI theme code (reference) B29K 105: 06 C08L 101: 00 C08L 101: 00 B29C 67/14 WF term (reference) 4F072 AB04 AB05 AB06 AB07 AB09 AB10 AB11 AB22 AD04 AD05 AD37 AD42 AD44 AD46 AG03 AH05 AH18 4F205 AB25 AD16 AH17 AH31 AH43 HA08 HA25 HA34 HB01 HC12 HF01 HK03 HK04 4L033 AA05 AB05 AC11 AC15 BA19 CA18

Claims (4)

[Claims] 1. A composite material characterized by being integrated with the fiber by applying a monomer and / or oligomer of a thermoplastic resin to the surface of the fiber and then polymerizing the monomer. 2. The composite material according to claim 1, wherein the volume content of the fibers is 60 vf% or more. 3. The composite material according to claim 1, wherein the fiber is an organic fiber having high strength and high elastic modulus. 4. A method for producing a composite material, which comprises applying a monomer and / or oligomer of a thermoplastic resin to a fiber surface and then polymerizing the same.