JPH0784034B2 - Fiber-reinforced resin molding and manufacturing method thereof - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a fiber-reinforced resin molded product and a method for producing the same, and more specifically, a matrix of a thermoplastic resin,
Fiber reinforced resin molding that is composed of a molecular orientation and reinforcing layer of silane crosslinked ultra high molecular weight polyethylene fibers laminated or embedded in this matrix, and that has excellent mechanical properties such as high elastic modulus and high strength, and excellent electrical properties. Regarding the body The present invention also relates to a method of making the same.

(Prior Art) Japanese Patent Application Laid-Open No. 58-171951 discloses a network of ultra-high molecular weight polyethylene fibers or polypropylene fibers, and a polyethylene crystal or polypropylene crystal region having a melting point or an adhesive point higher than that of the polyolefin fibers. At least 3 ° C
A composite structure consisting of a matrix composed of a low polymer is described, and this composite shows an actually measured strength higher than a theoretical estimated value, and the increase in the strength of this composite is caused by the crystallinity of fibers generated during molding. It is also stated that it may be due to certain favorable effects that more than offset the loss.

(Problems to be Solved by the Invention) Stretched fibers of ultra-high molecular weight polyethylene have a high elastic modulus and high tensile strength, but have the inherent drawback of polyethylene, that is, the poor heat resistance.

Generally, it is known that the heat resistance of polyolefin is improved by the molecular orientation of polyethylene or by the cross-linking of polyethylene, but there is a limit to the improvement of heat resistance in this conventional technique, and the melting point of polyethylene is 110 after all. To 140 ° C., which is a fundamentally unavoidable constraint of being in a relatively low range, and as far as the inventors of the present invention know, after exposing a molded body of polyethylene to a temperature of 180 ° C. for 10 minutes, Most of it melts and loses its strength.

Thus, polyolefin fibers are compounded with a matrix of thermoplastic resin at temperatures above their melting point,
Fiber reinforced resin moldings in which polyolefin fibers are present in the composite structure in the original oriented crystallization state have not yet been known.

Therefore, an object of the present invention is to have a composite structure of a matrix of a thermoplastic resin and a reinforcing layer of a polyolefin fiber laminated or embedded therein, in which the polyolefin fiber exists in its original oriented crystalline state. As a result, there is provided a fiber-reinforced resin molded product having a remarkably high elastic modulus and mechanical strength, and a method for producing the same.

Another object of the present invention is to have a composite structure of an olefin resin matrix and a molecular orientation and silane crosslinked ultra high molecular weight polyethylene fiber laminated or embedded in the matrix, and having a high elastic modulus, high strength and impact resistance. Another object of the present invention is to provide a fiber-reinforced resin molded article having excellent mechanical properties such as creep resistance, light weight, and electrical characteristics, and a method for producing the same.

(Means for Solving the Problems) According to the present invention, a matrix of a thermoplastic resin having a melting point or a softening point of 220 ° C. or less, and a molecular orientation and a silane-crosslinked ultrahigh molecular weight polyethylene fiber laminated or embedded in the matrix. The present invention provides a fiber-reinforced resin molded product comprising at least one of the above reinforcing layers, wherein the reinforcing layer substantially has an oriented crystal structure of ultrahigh molecular weight polyethylene fibers.

According to the present invention, a filament of molecularly oriented and silane-crosslinked ultra-high molecular weight polyethylene, or a nonwoven fabric, a woven fabric or a knitted fabric made of this filament is arranged in the plane direction and its end portion is constrained to have a melting point or a softening point. Provided is a method for producing a fiber-reinforced resin molded product, which is characterized in that it is combined with a melt of a thermoplastic resin having a point of 220 ° C. or lower.

(Function) The present invention is formed by combining a molecularly oriented silane crosslinked fiber of ultra high molecular weight polyethylene with a thermoplastic resin having a melting point or a softening point of 220 ° C. or lower under constraint conditions and the resin in a molten state into a composite structure. It is based on the novel finding that the oriented crystal structure of the fiber is substantially retained in the composite structure.

In the present specification, the melting point or softening point of a thermoplastic resin means the melting point uniquely for those having a melting point, and the softening point for those having no melting point.

The reinforcing fiber used in the present invention is produced by molding a product obtained by grafting silanes on ultra-high molecular weight polyethylene, and stretching the molded product to perform silane crosslinking. It has a novel property that the melting point of at least a part of the polymer chains constituting this is remarkably improved under restraint conditions as compared with the original melting point of the raw material ultrahigh molecular weight polyethylene. Note that the restrained condition means that the fiber is not positively tensioned, but the end is fixed to prevent free deformation, or the fiber is wrapped around another object such as a frame. Means

That is, the molecularly oriented silane crosslinked product of the ultrahigh molecular weight polyethylene used in the present invention is generally the original crystal of the ultrahigh molecular weight polyethylene obtained as the main melting peak during the second heating when measured by a differential scanning calorimeter in a restrained state. It has at least two crystal melting peaks (Tp) at a temperature at least 10 ° C higher than the melting temperature (Tm), and the heat of fusion is 40% or more based on the total heat of fusion (Tp) range
High temperature side melting peak (Tp ₁ ) from Tm + 35 ℃ to Tm + 120 ℃
The total amount of heat of fusion based on is 5% or more based on the total amount of heat of fusion.

The melting point of a polymer is associated with the dissolution of crystals in the polymer and is generally measured as an endothermic peak temperature associated with the dissolution of crystals in a differential scanning calorimeter. This endothermic peak temperature is constant if the type of the polymer is determined, and it hardly changes due to subsequent treatment, for example, stretching treatment or cross-linking treatment. Even with the well-known stretching heat treatment, it only moves to a high temperature side of approximately 15 ° C.

FIG. 1 of the accompanying drawings is an endothermic curve in a differential scanning calorimeter of molecularly oriented silane crosslinked filaments (fibers) of ultra high molecular weight polyethylene used in the present invention, and FIG. 2 is a raw material ultra high molecular weight polyethylene. 3 is an endothermic curve of the drawn filament of ultra-high molecular weight polyethylene of FIG. 2 under restrained conditions, and FIG. 4 is a cross-sectional view of ultra-high molecular weight polyethylene of FIG. 3 is an endothermic curve under restrained conditions for the unstretched filaments. For details of raw materials and processing conditions, refer to the examples described later.

From these results, the mere stretched product or silane cross-linked product of ultra-high molecular weight polyethylene shows an endothermic peak associated with crystal melting at about 135 ° C, which is almost the same as that of untreated ultra-high molecular weight polyethylene. In contrast, the peak area (heat of fusion) of the untreated ultra-high-molecular-weight polyethylene is at the position of the melting peak temperature in the stretch-crosslinking battle zone used in the present invention. It can be seen that the small peak remains, but the large peak shifts to a rather high temperature side.

FIG. 5 shows an endothermic curve when the sample of FIG. 1 was applied to a second run (the second temperature increase measurement after performing the measurement of FIG. 1). From the results of FIG. 5, the main peak of crystal melting appears at almost the same temperature as the melting peak temperature of untreated ultra-high molecular weight polyethylene in the case of reheating, and at the time of measurement in FIG. Since the orientation has almost disappeared,
The shift of the endothermic peak to the high temperature side in the sample of FIG.
It shows that it is closely related to the molecular orientation in the fiber.

The reason why the crystal melting temperature shifts to the high temperature side in the oriented crosslinked fiber used in the present invention has not yet been sufficiently clarified, but the present inventors presume the reason as follows. That is, when the silane-grafted ultra-high molecular weight polyethylene is subjected to a stretching operation, the silane-grafted portion selectively becomes an amorphous portion, and the oriented crystal portion is generated through this amorphous portion. Next, when this drawn fiber is crosslinked in the presence of a silanol condensation catalyst, a crosslinked structure is selectively formed in the amorphous part, and both ends of the oriented crystal part are fixed by silane crosslinking. In a normal stretched fiber, crystal melting proceeds from the amorphous part at both ends of the oriented crystal part, whereas in the stretched crosslinked fiber used in the present invention, the amorphous part at both ends of the oriented crystal part is selectively cross-linked to produce heavy polymer. It is considered that the melting temperature of the oriented crystal part is improved because the united chains are hard to move.

In the molecularly oriented silane crosslinked fiber of ultra-high molecular weight polyethylene used in the present invention, not only the fiber form but also the oriented crystal form is maintained even at a temperature higher than the original melting point of the polyethylene. By laminating or embedding in a molten thermoplastic resin under restraint conditions, a fiber-reinforced resin molded product having excellent mechanical properties such as tensile strength, bending strength, elastic modulus, and impact resistance can be obtained. .

(Explanation of Preferred Embodiment) Fiber-Reinforced Resin Molded Body In FIG. 6 showing an example of the fiber-reinforced resin molded body of the present invention, this molded body 1 comprises a thermoplastic resin matrix 2 having a melting point or a softening point of 220 ° C. or less and It consists of a reinforcing layer 3 of molecularly oriented and silane-crosslinked ultra high molecular weight polyethylene fibers embedded in or laminated with the matrix 2. The fiber reinforcing layer 3 may be provided as a single layer or a multilayer including two or more layers. In the specific example shown in FIG. 6, the fiber drop reinforcing layer 3 is completely embedded in the matrix of the thermoplastic resin, and both surfaces 4a, 4b of the molded body are substantially made of the thermoplastic resin, As shown in the specific example of FIG. 7, the fiber reinforcing layer 3 may be present on one or both of the surfaces 4a and 4b or in the vicinity thereof in the form of being integrally laminated with the resin matrix.

In the fiber-reinforced resin-formed product of the present invention, the silane-crosslinked ultrahigh molecular weight polyethylene fibers constituting the fiber-reinforced layer 3 substantially retain their oriented crystal structure. The reinforcing layer 3 is embedded or laminated on the entire surface of the molded body 1 and
At least uniaxially oriented molecular orientation and silane cross-linked ultra high molecular weight polyethylene filament tape,
Alternatively, it is made of a non-woven fabric, a woven fabric or a knitted fabric made of this filament.

The ratio of the fiber reinforced layer and the thermoplastic resin matrix is
Generally, the fiber-reinforced layer is 20 to 80% by volume, especially 40 to 40% by volume, though it varies considerably depending on the use and thickness.
It is desirable to have a proportion such that it accounts for 70% by volume.

When the volume ratio of the fiber reinforced layer is less than the above range,
If tensile strength, bending strength, elastic modulus, impact resistance, creep resistance, etc. are not sufficiently improved by fiber reinforcement, and if the volume ratio exceeds the above range, molding into an integrated fiber-reinforced resin molded product Tends to be difficult.

Reinforcing Layer The molecular orientation and silane-crosslinked ultrahigh molecular weight polyethylene fiber used in the present invention are thermoforming a composition containing an ultrahigh molecular weight polyethylene having an intrinsic viscosity [η] of 5 dl / g or more, a silane compound, a radical initiator and a diluent. Then, the silane compound-grafted ultra-high molecular weight polyethylene molded product is stretched, and a silanol condensation catalyst is impregnated into the stretched molded product of the molded product during or after stretching, and then the stretched molded product is contacted with water. It is manufactured by cross-linking.

Ultra high molecular weight polyethylene (A) is a decalin solvent 135
Intrinsic viscosity at ℃ [η] is 5dl / g or more, preferably 7
To 30 dl / g.

Such ultra-high molecular weight polyethylene is obtained by polymerizing ethylene or ethylene and a small amount of other α-olefins such as propylene, 1-butene, 4-methyl-1-pentene and 1-hexacene by so-called Ziegler polymerization. The polyethylene obtained has a much higher molecular weight.

On the other hand, as the silane compound used for the graft treatment,
Any silane compound that can be grafted and crosslinked can be used, and such a silane compound has both a radically polymerizable organic group and a hydrolyzable organic group, General formula RnSiY _4-n (1) In the formula, R is an organic group containing radically polymerizable ethylenic unsaturation, Y is a hydrolyzable organic group, and n is a number of 1 or 2. It is represented by.

As the radically polymerizable organic group, a vinyl group, an allyl group,
Butenyl group, an ethylenically unsaturated hydrocarbon group such as cyclohexenyl group, an acryloxyalkyl group, an alkyl group containing an ethylenically unsaturated carboxylic acid ester unit such as a methacryloxyalkyl group, and the like, vinyl Groups are preferred. Examples of the hydrolyzable organic group include an alkoxy group and an acyloxy group.

Suitable examples of silane compounds include, but are not limited to, vinyltoluethoxysilane, vinyltrimethoxysilane,
Vinyl tris (methoxyethoxy) silane and the like.

First, silane grafting and molding are performed by thermoforming a composition containing the above-mentioned ultrahigh molecular weight polyethylene, a silane compound, a radical initiator and a diluent by melt extrusion or the like. That is, the radical causes grafting of the silane compound onto the ultrahigh molecular weight polyethylene.

As radical initiators, all radical initiators used in this type of grafting process can be used, such as organic peroxides, organic peresters, tyronitrile, dimethylazoisobutyrate. In order to effectively perform grafting under the melt-kneading condition of ultra high molecular weight polyethylene,
The half-life temperature of the radical initiator is preferably in the range of 100 to 200 ° C.

A diluent is included with the above components to enable melt molding of silane-grafted ultra high molecular weight polyethylene. As such a diluent, a solvent for ultra-high molecular weight polyethylene or various wax-like substances compatible with ultra-high molecular weight polyethylene are used.

The silane compound is 0.1 to 10 parts by weight, particularly 0.2 to 5.0 parts by weight, and the radical initiator is a catalytic amount, generally 0.01 to 3.0 parts by weight, and particularly 0.0 per 100 parts by weight of the ultra high molecular weight polyethylene.
5 to 0.5 parts by weight and diluent 9900 to 33 parts by weight, especially 19
It is preferably used in an amount of 00 to 100 parts by weight.

Melt kneading is generally carried out at a temperature of 150 to 300 ° C., particularly 170 to 270 ° C., and the compounding is carried out by a Henschel mixer,
It may be performed by dry blending using a V-type blender or the like, or may be performed by melt mixing using a single-screw or multi-screw extruder.

The molten mixture is extruded through a rod spinneret and formed into filaments. In this case, the melt extruded from the rod spinneret can be drafted, that is, stretched in a molten state. Extrusion speed of molten resin in die / orifice
The ratio of V ₀ to the winding speed V of the unstretched solidified by cooling can be defined as the draft ratio by the following formula.

Draft ratio = V / V ₀ (2) The draft ratio is usually 3 or more, preferably 6 or more, although it depends on the temperature of the mixture, the molecular weight of the ultrahigh molecular weight polyethylene and the like.

The resulting unstretched filament is stretched. Stretching of the silane-grafted polyethylene filament is generally carried out at a temperature of 40 to 160 ° C, especially 80 to 145 ° C.
As the heat medium for heating and holding the unstretched filament at the above temperature, any of air, water vapor, and liquid medium can be used. However, as a heat medium, a solvent capable of eluting and removing the above-mentioned diluent and having a boiling point higher than the melting point of the molded body composition, specifically decalin, decane, kerosene, etc. When the operation is performed, it is possible to remove the above-mentioned diluent, and it is possible to eliminate the uneven drawing during the drawing and to achieve a high draw ratio.

The stretching operation can be performed in one stage or in multiple stages of two or more stages. Although the draw ratio depends on the desired molecular orientation effect, satisfactory results can be obtained by carrying out the draw operation so that the draw ratio is generally 5 to 80 times, particularly 10 to 50 times.

A silanol condensation catalyst is impregnated into the molded product during or after the stretching, and then the stretched molded product is brought into contact with water to crosslink.

As the silanol condensation catalyst, use can be made of ones known per se, for example, dialkyltin dicarboxylates such as dibutyltin dilaurate, dibutyltin diacetate, dibutyltin dioctoate; organic titanates such as tetrabutyl titanate; lead naphthenate and the like. You can These silanol condensation catalysts can be effectively impregnated into these molded products by bringing them into contact with an unstretched molded product or a stretched molded product while being dissolved in a liquid medium. For example, when the stretching treatment is performed in a liquid medium, by dissolving the silanol condensation catalyst in the stretching liquid medium, it is possible to impregnate the molded product with the silanol condensation catalyst at the same time as the stretching operation. it can.

The amount of the silanol condensation catalyst to be impregnated in the molded product may be a so-called catalytic amount, and it is difficult to directly specify the amount, but in general, it is unstretched or in a liquid medium in contact with the molded product of the stretching agent. 10 to 100% by weight, especially 25 to 75% by weight
A satisfactory result is obtained by adding the silanol condensation catalyst in an amount of 10 and contacting the liquid medium with the filament.

The cross-linking treatment of the stretched molded product is performed by bringing the stretched molded product of the silane-grafted ultrahigh molecular weight polyethylene impregnated with the silanol condensation catalyst into contact with water. As the conditions for the crosslinking treatment, it is advantageous to bring the stretched molded product into contact with water at a temperature of 50 to 130 ° C. for 3 to 24 hours. For this purpose, water is preferably applied to the stretch-molded product in the form of hot water or hot steam. At the time of this cross-linking treatment, the stretched molded article may be placed under restrained conditions to prevent orientation relaxation, or conversely, under unconstrained conditions, some degree of orientation relaxation may occur. .

The mechanical strength such as tensile strength is further improved by further subjecting the stretched molded body to a crosslinking treatment and then a stretching treatment (usually 3 times or less).

The molecular orientation and silane-crosslinked ultra high molecular weight polyethylene fibers used in the present invention have a crystal melting peak (Tp) at a much higher temperature than the crystal melting temperature (Tm) of the ultra high molecular weight polyethylene body under the constraint conditions. It has the surprising feature of showing.

The original crystal melting temperature (Tm) of ultra high molecular weight polyethylene is
It can be determined by a method of completely melting the fiber once and then cooling it to relax the molecular orientation in the molded body and then raising the temperature again, that is, a second run in a so-called differential operation type calorimeter.

As is clear from FIG. 1 described above, the filament used in the present invention has at least two crystal melting peaks (Tp) at a temperature which is at least 10 ° C. higher than the original crystal melting temperature (Tm) of ultrahigh molecular weight polyethylene. And the heat of fusion based on this crystal melting peak (Tp) per total heat of fusion is 40% or more, particularly 60% or more.

In general, the crystalline melting peak (Tp) in the fiber used in the present invention has a high temperature side melting peak (Tp ₁ ) in the temperature range Tm + 35 ° C. to Tm + 120 ° C. and a temperature range Tm + 10 ° C. to Tm + 35 ° C.
It often appears as a low-temperature side peak (Tp ₂ ) in ₂ ), and the melting peak of Tm itself is extremely small.

When the amount of silane grafts on the molded product is small, the melting point at the high temperature side (Tp ₁ ) does not show a clear maximum (peak) on the melting curve, and a broad maximum point (peak) or at the low temperature side (Tp 1) It often appears as a shoulder or tail over the high temperature side of ₂ ) from Tm + 35 ℃ to Tm + 120 ℃.

Also, when the Tm melting peak is extremely small, it may not be visible because it is hidden by the melting peak shoulder of Tp ₁ . If Tm
Even if there is no melting peak of, the function of the ultra high molecular weight polyethylene filament is not hindered. Tm + 35 ℃ ~ Tm
High temperature side melting peak (Tp ₁ ) at + 120 ℃ and temperature range Tm
The low temperature side melting peak (Tp ₂ ) at + 10 ° C. to Tm + 35 ° C. may be further divided into two or more melting peaks depending on the sample preparation conditions and the melting point measurement conditions.

These high crystal melting peaks (Tp ₁ , Tp ₂ ) act to significantly improve the heat resistance of ultra-high molecular weight polyethylene filaments, but contribute to the improvement of the strength retention rate after high temperature thermal history. Is the melting peak on the high temperature side (T
p ₁ ).

Therefore, the total amount of heat of fusion based on the high temperature side melting peak (Tp ₁ ) in the temperature range Tm + 35 ° C. to Tm + 120 ° C. is preferably 5% or more, and particularly 10% or more based on the total amount of heat of fusion.

As long as the sum of the heat of fusion based on the high temperature side melting peak (Tp ₁ ) satisfies the above value, if the high temperature side melting peak (Tp ₁ ) does not appear as a major peak, that is, it is small. Even if an aggregate of peaks or a broad peak is obtained, the heat resistance may be slightly lost, but the creep resistance is excellent.

The degree of molecular orientation in the molded body can be known by an X-ray diffraction method, a birefringence method, a fluorescence polarization method and the like. In the case of the stretched silane cross-linked filament used in the present invention, for example, Yukichi Kure, Kiichiro Kubo: Industrial Chemistry Magazine, Vol. 39, page 992 (1939), the degree of orientation by half width, that is, the formula In the formula, H ° is the half width (°) of the intensity distribution curve along the Debye ring of the strongest paratropic plane on the equator line.

It is desirable from the viewpoint of heat resistance and mechanical properties that the molecular orientation is such that the compounding degree (F) defined by is 0.90 or more, particularly 0.95 or more.

In addition, the grafting amount of silane is 135 ° C.
It can be determined by carrying out an extraction treatment in p-xylene for 4 hours at the above temperature to extract and remove unreacted silane and the contained diluent, and quantify Si by a gravimetric method or an atomic absorption method. The silane graft amount of the fiber used in the present invention is preferably 0.01 to 5% by weight, particularly 0.035 to 3.5% by weight, expressed as Si% by weight based on ultrahigh molecular weight polyethylene, from the viewpoint of heat resistance. That is, when the grafting amount is less than the above range, the crosslinking density is smaller than that of the present invention, while when it is more than the above range, the crystallinity decreases, and the heat resistance is insufficient. Become.

In the molecular orientation-silane cross-linked fiber used in the present invention, since the crystal melting temperature of at least a part of the polymer chains constituting the fiber is shifted to the extremely high temperature side as described above, it is extremely excellent in heat resistance. , The strength retention rate after applying heat history at 160 ℃ for 10 minutes is 80% or more, preferably 180 ℃
The strength retention rate after applying a heat history of 10 minutes at 60% or more, especially 80% or more, and the strength retention rate after applying a heat history of 5 minutes at 200 ° C is 80% or more. That is, it shows surprising heat resistance that cannot be expected from conventional ultra high molecular weight polyethylene.

The filament used in the present invention has a heat-resistant creep property,
For example, under the conditions of load: 30% breaking load, temperature: 70 ° C., an uncrosslinked filament shows an elongation of 50% or more after standing for 1 minute, whereas the filament is 30% or less, further 20% or less, which is extremely excellent. There is.

Further, in the filament used in the present invention, under the condition of load: 50% breaking load, temperature: 70 ° C., the uncrosslinked material undergoes elongation fracture before waiting 1 minute, whereas elongation after standing for 1 minute
Shows 20% or less.

Moreover, since this molded product contains grafted and crosslinked silanes, it has excellent adhesiveness, particularly adhesiveness with various resins, and this fact can be easily understood by referring to the examples described later. Be understood by.

Further, this filament is made of ultra-high molecular weight polyethylene, and since it is effectively imparted with molecular orientation, it has excellent mechanical properties.For example, in the form of a drawn filament, the elastic modulus is 20 GPa or more and 1.2 GPa or more. Indicates tensile strength.

The fineness of the monofilament of the molecularly oriented silane crosslinked filament is not particularly limited, but it is preferably 0.5 to 20 denier, particularly 1 to 10 denier in terms of strength.

This filament is generally used in the form of a multifilament, a multifilament plied yarn, a non-woven fabric, a woven fabric or a knitted fabric made of the same, as a fiber reinforcing layer for a thermoplastic resin.

Polymer Matrix The thermoplastic polymer for the matrix used in the present invention must have a melting point or softening point of 220 ° C. or lower. When the melting point or softening point exceeds 220 ° C., the molecular orientation and the silane-crosslinked ultrahigh molecular weight polyethylene fibers incorporated in the fiber-reinforced resin molded product substantially lose their oriented crystal structure. The thermoplastic polymer for matrix used preferably has a melting point or softening point of 100 to 200 ° C, particularly 150 to 180 ° C.

Suitable examples of such a matrix polymer include low-, medium- or high-density polyethylene, linear low density polyethylene, polypropylene, crystalline propylene-ethylene copolymer, propylene-butene-1 copolymer and ethylene. -Butene-1 copolymer ethylene-propylene-butene-
1 homopolymers or copolymers of crystalline olefins such as copolymers; ethylene / propylene copolymer rubbers, ethylene-propylene-non-co-diene copolymer rubbers, α-olefins such as ethylene, and butadiene An olefin elastomer such as a copolymer with a conjugated diene or a non-conjugated diene such as ethylidene norbornene or dicyclopentadiene; further, ethylene-vinyl acetate copolymer, ethylene-ethyl acrylate copolymer, ethylene-vinyl Examples thereof include copolymers of olefins such as alcohol copolymers, ethylene-vinyl chloride copolymers and ion-crosslinked olefin copolymers, and other ethylenically unsaturated monomers. These olefinic matrix polymers are particularly excellent in thermal adhesiveness to the fiber reinforcing layer.

For the production of the fiber-reinforced resin molded product, it is desirable that the polymer used has a melt flow rate CAS TMD-1238 of 1 g / 10 min or more, particularly 5 g / 10 min or more.

Of course, the thermoplastic polymer that can be used is not limited to those exemplified above, and may be another polymer as long as the melting point or the softening point is within the above range, for example, polystyrene, styrene- Acrylonitrile copolymer, styrene-
Styrene resins such as butadiene copolymer and ABS resin;
Soft vinyl chloride resin Vinylidene chloride-acrylic copolymer, vinylidene chloride-vinyl chloride copolymer, chlorine-containing polymers such as chlorinated polyethylene, chlorinated vinyl resin; polymethyl methacrylate, methyl methacrylate-ethyl acrylate copolymer Acrylic polymer such as coalescing; Nylon-11,
Low melting point polyamides such as nylon-12 and nylon 6 / nylon 66 copolymers; use low melting point or low softening point polyesters such as ethylene / terephthalate / isophthalate copolymer polyesters and ethylene / butylene / terephthalate copolymer polyesters You can also

The thermoplastic polymer matrix used in the present invention may include compounding agents known per se, such as a lubricant or a release agent, an antioxidant, a softening agent or a plasticizer, a filler, a colorant, a foaming agent, and a crosslinking agent. It can be blended according to one or more known formulations.

Manufacturing method The molded body of the present invention is produced by arranging the fiber reinforced layers of the various forms described above in the plane direction and, for example, in a state in which at least the ends thereof are constrained, it is combined with the melt of the thermoplastic resin described above. To be done.

The combination of the fiber-reinforced layer and the melt of the thermoplastic resin is performed by various methods. For example, a preformed thermoplastic resin film or sheet and a fiber reinforcing layer are superposed and the thermoplastic resin is melted because the abandoned crystal structure of the ultra high molecular weight polyethylene fiber in the reinforcing layer is substantially The stack is crimped at the temperature maintained. This pressure bonding operation may be performed by a batch operation or a semi-continuous operation like a hot press, or continuously like a hot roll press. During this crimping operation, it is important that the fiber reinforcing layer has its ends restrained, which means, for example, whether the fibers are pre-wound around the press substrate to restrain the ends,
Alternatively, it can be achieved by applying an appropriate tension to the fiber-reinforced layer during the crimping operation. When the fibers are arranged in the machine longitudinal direction and the direction perpendicular to the machine direction, tension may be applied in both directions so as not to allow free shrinkage of the fibers.

Alternatively, the extruded product of the thermoplastic resin in a molten state and the fiber reinforcing layer may be superposed, and the two may be pressure-bonded to be combined. For example, a thermoplastic resin may be extruded between two fiber-reinforced layers to combine them,
Alternatively, a thermoplastic resin may be extruded on both sides of the single-layer fiber-reinforced layer to integrate them. Of course, a plurality of fiber-reinforced layers and a plurality of thermoplastic resin extrudates may be alternately laminated to perform pressure-bonding integration.

The fiber-reinforced resin molded product according to the present invention is not limited to a two-dimensional shape. For example, a fiber-reinforced layer is annularly arranged in the form of a filament or a nonwoven fabric, woven or knitted product of this filament, and a thermoplastic resin is extruded into an annular shape through a circular die, and both are integrated inside or outside the die. By doing so, a tubular fiber-reinforced resin molding can be obtained.
Further, when the above-mentioned molding method is applied with the electric wire or the optical cable as the core, the sheath of the fiber-reinforced molded body can be formed.

EFFECTS OF THE INVENTION According to the present invention, molecular orientation and silane cross-linked ultra high molecular weight polyethylene fibers are combined with a melt of a thermoplastic polymer under constrained conditions to form a matrix in the polymer. It can be present as a fiber-reinforced layer while substantially retaining the compound crystal structure of the fiber.

Therefore, the excellent tensile properties of the fiber are imparted to this molded product, and because the fiber is silane-modified, it has excellent adhesiveness not only to polyethylene but also to other polymers, Thus, a molded product having a high elastic modulus and high strength can be obtained.

When a polyolefin matrix is used,
It has excellent electrical insulation properties, less inductive loss and superior electrical characteristics compared to a matrix using epoxy resin or unsaturated polyester resin.

(Examples) Next, the present invention will be described more specifically with reference to Examples.
The present invention is not limited to the examples as long as the gist of the present invention is not exceeded.

Example 1 <Preparation of silane crosslinked stretched ultra high molecular weight polyethylene fiber> Grafted and spun ultra high molecular weight polyethylene (intrinsic viscosity [η] = 8.20 dl / g
) Powder: 100 parts by weight of vinyltrimethoxysilane (manufactured by Shin-Etsu Chemical): 10 parts by weight and 2,5-dimethyl-2,5-
Di (tert-butylperoxy) hexane (NOF Corporation:
Product name, Perhexa 25B): After uniformly blending 0.1 part by weight, powder of paraffin wax (made by Nippon Seiro Co., Ltd., product name, Lubax) to 100 parts by weight of ultra high molecular weight polyethylene.
(1266, melting point = 69 ° C.): 370 parts by weight were added and mixed to obtain a mixture. Then, the mixture was melt-kneaded at a preset temperature of 200 ° C. using a screw type extruder (screw diameter = 20 mmφ, L / D = 25), and subsequently the melt was orifice diameter 2 mm.
The silane grafting was completed by spinning from the die. The spun fiber was cooled and solidified with air at room temperature in an air gap of 180 cm to obtain an unstretched ultra high molecular weight polyethylene silane graft fiber. The undrawn yarn had a denier of 800, and the draft ratio during spinning was 36.4. The winding speed at this time was 90 m / min.

Quantification of the amount of silane grafted About 8 g of unstretched graft fiber prepared by the above method
It was dissolved in 200 cc of p-xylene heated and kept at ℃. Then, ultra-high molecular weight polyethylene was precipitated in excess hexane at room temperature to remove paraffin wax and unreacted silane compound. After that, the graft amount determined by the gravimetric method as Si wt% was 0.57 wt%.

Stretching The grafted unstretched fiber spun from the ultra high molecular weight polyethylene mixture by the above method was stretched under the following conditions to obtain oriented stretched fiber. Two-stage drawing was performed in a drawing tank using n-decane as a heating medium using three godet rolls. At this time, the temperature in the first drawing tank was 110 ° C, the temperature in the second drawing tank was 120 ° C, and the effective length of the tank was 50 cm. In drawing, the rotation speed of the first godet roll was set to 0.5 m / min and the rotation speed of the third godet roll was changed to obtain a fiber having a desired draw ratio. Further, the rotation speed of the second godet roll was appropriately selected within a range in which stable stretching was possible. However, the stretching ratio was calculated and calculated from the rotation ratio of the first godet roll and the third godet roll.

The obtained fiber was dried at room temperature under reduced pressure to obtain a stretched ultra high molecular weight polyethylene silane graft fiber.

Impregnation of cross-linking catalyst When the oriented fiber of the silane compound-grafted ultra-high molecular weight polyethylene prepared by the above method is further cross-linked, n-decane and dibutyl tin dilaurate in the same amount as n-decane are used as a heating medium in the second stretching tank. The mixture was used to extract paraffin wax and at the same time to impregnate fibers with dibutyltin dilaurate. The obtained fiber was dried under reduced pressure at room temperature until the smell of decane disappeared.

Crosslinking After this, the fibers were left in boiling water for 12 hours to complete the crosslinking.

Measurement of gel fraction About 0.4 g of the silane-crosslinked stretched ultrahigh molecular weight polyethylene fiber obtained by the above method was placed in an Erlenmeyer flask equipped with a condenser containing 200 ml of paraxylene and stirred in the boiling state for 4 hours. Then insoluble material made of stainless steel 300 m
I passed by the mesh of esh. After drying under reduced pressure at 80 ° C., the weight was measured and the weight of the insoluble matter was determined. The gel fraction was calculated by the following formula.

The gel fraction of the above prepared sample was 51.4%.

The tensile modulus, tensile strength and elongation at break were measured at room temperature (23 ° C) using an Instron universal testing machine type 1123 (manufactured by Instron). The sample length between the clamps was 100 mm and the tensile speed was 100 mm / min. However, the tensile modulus is the initial modulus. The fiber cross-sectional area required for the calculation was obtained by measuring the weight and length of the fiber with the density of polyethylene being 0.96 g / cm ³ .

Table 1 shows the physical properties of the silane-crosslinked stretched ultrahigh molecular weight polyethylene fiber thus obtained.

The crystal melting temperature (Tm) of the ultrahigh molecular weight polyethylene, which is the main melting peak during the second heating, is 132.2.
The ratio of the heat of fusion based on Tp to the heat of fusion of all crystals and the ratio of the heat of fusion based on Tp ₁ to the heat of fusion of all crystals were 73% and 22%, respectively. At this time
The main Tp ₂ is 151.0 ° C and the main Tp ₁ is 2
It was 26.5 ° C.

Evaluation of Creep Properties The creep test was performed using a thermal stress strain measuring device TMA / SS10 (manufactured by Seiko Electronics Co., Ltd.) at a sample length of 1 cm and an ambient temperature of 70 ° C. Eighth result at 30% of breaking load
Shown in the figure. The silane-crosslinked stretched ultrahigh molecular weight polyethylene fiber (Sample-1) prepared in this Example is the stretched ultrahigh molecular weight polyethylene fiber (Sample-2) prepared in Comparative Example 1 described later.
In each case, it can be seen that the creep characteristics are remarkably improved.

At an ambient temperature of 70 ° C, 50% of the breaking load at room temperature
In a creep test conducted under a load equivalent to%, Table 2 shows the elongations 1 minute, 2 minutes, and 3 minutes after the loading.

Strength retention rate after heat history The heat history test was performed by disposing in a gear open (perfect open: manufactured by Tabai Seisakusho). The sample was fixed to both ends of the sample by folding it back to a stainless frame having a plurality of pulleys at both ends and having a length of about 3 m. At this time, both ends of the sample were fixed so that the sample did not sag, and no tension was positively applied to the sample. The results are shown in Table 3.
Shown in.

From Table 3, it can be seen that the silane crosslinked stretched ultra high molecular weight polyethylene fibers used in this example have threatening heat strength retention characteristics.

Measurement of degree of orientation by X-ray diffraction The fiber was wound around a Phillips type holder for 10 to 20 times, one side was separated, and a bundle was used for the measurement. The degree of orientation was obtained by measuring the (110) plane reflection of the polyethylene crystal appearing on the equator line with a diffractometer to obtain the reflection intensity distribution. The calculation followed the method of Kure et al. The degree of orientation thus obtained was 0.955.

<Molding of Fiber Reinforced Resin Molded Body> High density polyethylene powder (intrinsic viscosity [η] = 2.3 dl / g, melting point 127 ° C.) was used as the matrix resin, and the silane crosslinked stretched ultra high molecular weight polyethylene prepared by the above-mentioned method A fiber-reinforced resin molding was obtained by the following method using the fiber as a reinforcing fiber. There is a square space of 150 x 150 mm, and the width of the outer periphery is 15 mm. The stainless steel metal frame with a thickness of 1 mm is wrapped with the above-mentioned silane crosslinked stretched ultra high molecular weight polyethylene fiber in a total of 8 layers in the directions orthogonal to each other. It was At this time, in each layer, the adjacent fibers adhered to each other but did not overlap each other. After that, the above-mentioned high-density polyethylene powder having the same weight as the silane cross-linked stretched ultra high molecular weight polyethylene fiber required for lamination was uniformly placed on the metal frame space laminated surface, and the metal frame was sandwiched between two stainless plates, Then, it was heated at 170 ° C. for 6 minutes with a heating press, and each pressure was applied. At this time, the applied pressure was adjusted to be 50 kg / cm ² . After that, the mixture was cooled with a water-cooled press to complete the molding. Then, the periphery of the central space of the metal frame was cut off to obtain a sample for measuring physical properties.

The obtained sample had a thickness of 1.5 mm and a silane crosslinked stretched ultra high molecular weight fiber content of 50% by volume. The flexural modulus and flexural strength of the sample were measured using an Instron universal tester Model 1123 (manufactured by Instron) at room temperature (23 ° C) according to JIS K691.
1 (ASTM D790). At this time, the test piece sample was prepared by punching the above sample with a rectangular dumbbell for bending test of 50 mm × 25 mm so as to be orthogonal to the fiber. Table 4 shows the bending strength and bending elastic modulus of the obtained sample.

Tensile yield strength and tensile modulus are JIS K6760 (ASTM D638-68
It was measured based on. However, the test piece at this time was prepared by punching the above sample with a JIS No. 2 dumbbell in a direction orthogonal to the fiber. The results are shown in Table 5.

It can be seen that, as compared with Comparative Example 2 which will be described later, the effect as a reinforcing fiber is sufficiently exhibited even after performing high temperature molding that exceeds the common sense of polyethylene fiber.

Example 2 <Molding of Fiber Reinforced Resin Molded Product> Polypropylene powder (intrinsic viscosity [μ] = 2.0 dl / g, melting point = 160 ° C.) was used as the matrix resin, and the method described in Example 1 was used as the reinforcing fiber. Using the prepared silane crosslinked stretched high molecular weight polyethylene fiber, a fiber reinforced resin molded product is molded under the following conditions. The above-mentioned silane-crosslinked stretched ultra high molecular weight polyethylene fibers are alternately wound in a perpendicular direction on a stainless steel frame having a 150 mm × 150 mm square space and a perimeter width of 15 mm and a thickness of 1 mm so as to form a total of 8 layers on the front and back sides. At this time, the adjacent fibers in each layer are in close contact with each other and do not overlap each other. After this, the above-mentioned polypropylene powder of the same weight as the silane crosslinked stretched ultra high molecular weight polyethylene fibers necessary for lamination was placed on the metal frame space part lamination surface, and the metal frame was sandwiched between two stainless steel plates with a heat press. 180
Pressurize and heat at ℃ for 6 minutes. The pressing force at this time is 25 kg
/ cm ² . Then, it is cooled in a water cooling press to complete the molding. The thickness of the obtained fiber reinforced resin molding is 1.5 mm, and the present content of this silane crosslinked stretched high molecular weight polyethylene fiber is 47% by volume. Table 6 shows the flexural modulus and flexural strength of the fiber-reinforced resin molded product measured by the method described in Example 1.

Furthermore, the tensile yield strength measured by the method described in Example 1,
The tensile elastic modulus is shown in Table 7.

Comparative Example 1. Preparation of Ultra High Molecular Weight Polyethylene Stretched Fiber Powder of ultra high molecular weight polyethylene (intrinsic viscosity [η] = 8.20): 100 parts by weight and paraffin wax powder described in Example 1: 320 parts by weight. It was spun by the method described in 1.
At this time, the draft ratio was 25 times and the undrawn yarn fineness was 1000 denier. Then, it was similarly stretched to obtain a stretched fiber. Table 8 shows the physical properties of the obtained fibers.

The melting characteristic curve of this fiber (Sample-2) is shown in FIG.
The original crystal melting temperature Tm obtained as the main melting peak at the second temperature rise is 132.2 ° C, and the ratio of the heat of fusion based on Tp to the total heat of fusion of the crystal and the ratio of the heat of fusion based on Tp ₁ to the heat of total crystal fusion Are 32.1%,
And 1.7%.

The creep characteristics were measured by the method described in the section <Evaluation of creep characteristics> in Example 1. The results are shown in Fig. 8.

Further, in the measurement of creep characteristics (atmosphere temperature = 70 ° C., load = 50% of the breaking load at room temperature) carried out in the same manner as in the method described in Example 1, the sample fractured immediately after the loading. The adhesive strength was measured by the method described in the section <Evaluation of adhesiveness> of Example 1. The results are shown in FIG. 9 together with Example 1.

The strength retention rate after heat history was measured by the method described in the section of <strength retention rate after heat history> in Example 1, but the oven temperature was 180 ° C. Melted.

<Molding of Fiber Reinforced Resin Molded Product> Using the high-density polyethylene powder described in Example 1 as a matrix resin, the method described in Example 1 was used to heat and press at 170 ° C. for 6 minutes with a heating press. The above-mentioned ultrahigh molecular weight polyethylene fiber laminate was embedded in the above-mentioned high-density polyethylene by pressing, and an attempt was made to form a fiber-reinforced resin molded body. After cooling, when the fiber layer inside the molded body was visually observed, the fibers were melted and dispersed as islands. The physical properties of this molded product were the same as those of Sample-C of Comparative Example 2 described later.

Comparative Example 2. The high-density polyethylene powder described in Example 1 was used as the matrix resin, and heated at 170 ° C. in a heat press molding machine.
A high-density polyethylene press-molded product was obtained by heating and pressurizing for 6 minutes and then pressing and cooling again with a cooling press-molding machine. Table 9 shows the flexural strength and flexural modulus measured by the method described in Example 1.

Table 10 shows the tensile yield strength and tensile elastic modulus measured by the method described in Example 1.

Comparative Example 3. Using the polypropylene powder described in Example 2 as a matrix resin, pressurizing and heating at 180 ° C. for 6 minutes in a press molding machine, and then pressing and cooling again in a cooling press molding machine. By doing so, a polypropylene press-molded product was obtained. Flexural strength measured by the method described in Example 1,
The flexural modulus is shown in Table 11.

Also, the tensile yield point strength measured by the method described in Example 1,
Table 12 shows the tensile modulus.

Example 3 <Molding of fiber reinforced resin molding> Nylon 12 powder (relative viscosity =
2.45, melting point = 176 ° C.) and using the silane crosslinked stretched ultra high molecular weight polyethylene fiber prepared by the method described in Example 1 as a reinforcing fiber, a fiber-reinforced resin molded product is obtained by the following method. The above-mentioned silane cross-linked stretched ultra high molecular weight polyethylene fiber is wound around a square stainless steel frame having a 150 mm x 150 mm square space and an outer peripheral width of 15 mm and a thickness of 1 mm so that a total of 8 layers are alternately arranged in the orthogonal direction. . At this time, the adjacent fibers in each layer are in close contact with each other and do not overlap each other. Then, the nylon 12 powder having the same weight as the silane cross-linked stretched ultra high molecular weight polyethylene fiber necessary for lamination was placed on the metal frame lamination surface, and the metal frame was sandwiched between two stainless steel protoss, and the heat press molding machine was used. And pressurize and heat at 195 ° C for 6 minutes. The pressing force at this time is 50 kg / cm ² .
Prior to this, the nylon 12 powder is dried at 105 ° C for 12 hours under a nitrogen atmosphere. Next, the molding is completed by pressurizing and cooling with a water-cooled press molding machine. The thickness of the obtained fiber reinforced resin molding is 1.5 mm, and the content of the silane crosslinked stretched ultra high molecular weight polyethylene fiber is 52% by volume. Table 13 shows the flexural modulus and flexural strength of the outer wire reinforced resin molded product measured by the method described in Example 1.

Further, Table 14 shows the tensile yield strength and the tensile elastic modulus measured by the method described in Example 1.

Comparative Example 4. Nylon 12 powder as described in Example 3 was used as a matrix resin, heated and pressed in a heating press molding machine at 195 ° C. for 6 minutes, and then pressed and cooled again in a cooling press molding machine. 12 press molded products were obtained. The bending strength and bending elastic modulus measured by the method described in Example 1 are shown in Table 15.
Shown in.

In addition, Table 16 shows the tensile yield strength and tensile elastic modulus measured by the method described in Example 1.

[Brief description of drawings]

FIG. 1 shows the endothermic curve of the silane-crosslinked stretched ultrahigh molecular weight polyethylene fiber prepared by the method of Example 1 measured under the restraint conditions in the differential scanning calorimeter at the first temperature rise. FIG. 2 shows the endothermic curve at the first temperature rise of the ultrahigh molecular weight polyethylene powder used in Example 1 molded into a press sheet having a thickness of 100 μ at 200 ° C. FIG. 3 shows the endothermic curve of the ungrafted stretched ultra high molecular weight polyethylene fiber prepared in Comparative Example 1 at the first temperature rise. In FIG. 4, the paraffin wax of the undrawn yarn silane-grafted in Example 1 was extracted with hexane at room temperature, impregnated with dibutyltin dilaurate, and then crosslinked by the method of Example 1 for the first ascent. The endothermic curve at warm temperature is shown. Further, FIG. 5 shows an endothermic curve of the silane crosslinked stretched ultra high molecular weight polyester fiber of FIG. 1 at the time of the second temperature increase (second run). 6 and 7 are schematic views of the molded fiber-reinforced resin molded product (although the number of laminated layers is different from that in the examples). FIG. 8 is a diagram showing the creep property of the stretch-oriented ultrahigh molecular weight polyethylene fibers prepared in Example 1 and Comparative Example 1, which is 70% at a load of 30% of the breaking load measured at room temperature. The results are measured under the atmosphere. FIG. 9 shows the relationship between the embedding length and the pull-out force in the adhesion test of the silane crosslinked stretched ultra high molecular weight polyethylene fiber prepared in Example 1 and the oriented ultra high molecular weight polyethylene fiber prepared in Comparative Example 1. It is a diagram showing.

Claims (5)

[Claims] 1. A thermoplastic polymer matrix having a melting point or a softening point of 220 ° C. or less, and at least one layer of a molecular orientation and a reinforcing layer of silane-crosslinked ultrahigh molecular weight polyethylene fibers laminated or embedded in the matrix. A fiber-reinforced resin molding, wherein the reinforcing layer substantially holds an oriented crystal structure of ultrahigh molecular weight polyethylene fibers. 2. The crystal fusion of the ultrahigh molecular weight polyethylene, which is the molecular orientation and the silane crosslinked ultrahigh molecular weight polyethylene fiber, is determined as a main melting peak at the second temperature rise when measured by a differential scanning calorimeter in a restrained state. It has at least two crystal melting peaks (Tp) at a temperature at least 10 ° C higher than the temperature (Tm), and the heat of fusion based on this crystal melting peak (Tp) is 40% or more and the temperature range Tm + 35. The total amount of heat of fusion based on the melting peak (Tp ₁ ) on the high temperature side at ℃ to Tm + 120 ℃ is 5% of the total heat of fusion
The fiber-reinforced resin molded product according to claim 1, which has the characteristics described above. 3. The fiber-reinforced resin molded product according to claim 1, wherein the thermoplastic polymer is an olefin polymer. 4. The reinforcing layer is laminated or embedded over the entire surface of the molded product, and has a molecular orientation and a silane-crosslinked ultrahigh molecular weight polyethylene filament oriented in at least one axial direction of the molded product, or a nonwoven fabric composed of this filament. The molded article according to claim 1, which is made of a woven fabric or a woven fabric. 5. A filament having molecular orientation and silane cross-linked ultra high molecular weight polyethylene, or a nonwoven fabric, woven fabric or knitted fabric made of this filament is arranged in the plane direction and its end portion is constrained to have a melting point or a softening point. A method for producing a fiber-reinforced resin molded product, which comprises incorporating the thermoplastic resin melt at 220 ° C or lower.