JPH10166465A - Production of fiber reinforced resin foam - Google Patents

Abstract

PROBLEM TO BE SOLVED: To efficiently and easily produce long fiber reinforced resin foam by a relatively simple process even if the cross-sectional shape thereof is complicated. SOLUTION: A foamable and crosslinkable resin compsn. 4 is held to a plurality of fiber bundles 3 consisting of a large number of continuous monofilaments and a fiber reinforced thermoplastic resin sheet 5 is continuously supplied to the peripheries of the fiber bundles while shaped into a hollow member to enclose the resin compsn. 4 and the fiber bundles and the resin compsn. 4 is foamed within the hollow member 5' to shape the hollow member 5' into a desired cross-sectional shape along a prescribing member 26 by the foaming pressure of the resin compsn. and the foamed resin compsn. 4 is crosslinked on the way of shaping or after shaping.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a fiber-reinforced resin foam having a structure in which the surface of a core layer made of a synthetic resin foam is covered with a skin layer made of a fiber-reinforced thermoplastic resin.

[0002]

2. Description of the Related Art Light weight, high specific strength and specific rigidity,
As a resin molded article suitable for use as a building material or the like, conventionally, a fiber reinforced resin foam having a core layer made of a synthetic resin foam and a skin layer made of a fiber reinforced synthetic resin is known.

[0003] As a method for producing such a fiber-reinforced resin foam, a method of tightly filling a phenolic resin foam into a hollow molded article obtained by press-molding a polypropylene prepreg has been conventionally known. Kaihei 7-9597
issue).

[0004]

However, according to the above-mentioned conventional manufacturing method, it is necessary to press-mold the polypropylene prepreg into a desired irregular cross-sectional shape in advance. Since it is difficult to form a complicated cross-sectional shape by molding, there is a problem that a fiber-reinforced resin foam having a complicated cross-sectional shape cannot be obtained. Further, since the skin layer is formed by press molding, there is a disadvantage that it is substantially impossible to obtain a long molded body.

It is an object of the present invention to efficiently and easily produce a long fiber-reinforced resin foam even in a fiber-reinforced resin foam having a complicated cross-sectional shape by a relatively simple process. It is to provide a method that can be manufactured.

[0006]

Means for Solving the Problems In order to achieve the above object, in the method for producing a fiber-reinforced resin foam of the present invention, a foamable and crosslinkable resin composition is applied to a plurality of fiber bundles comprising a large number of continuous monofilaments. And surrounding the fiber bundle holding the composition by supplying one or more fiber-reinforced thermoplastic resin sheets continuously while shaping it into a hollow body, and wrapping the inside of the hollow body. The foamable and crosslinkable resin composition is foamed, and the foaming pressure is used to shape the hollow body into a desired cross-sectional shape along the regulating member, and the foamable and foamed foam is formed during or after the shaping. A method of crosslinking a crosslinkable resin composition is employed.

According to the method of the present invention, while continuously forming a fiber-reinforced thermoplastic resin sheet into a simple hollow body such as a cylindrical shape, a plurality of continuous monofilaments are formed inside the sheet. To expand the foamable and crosslinkable resin composition while wrapping the foamable and crosslinkable resin composition held in the fiber bundle, and to form the hollow body along the regulating member by the foaming pressure. Eventually, the fiber-reinforced resin layer serving as the skin layer and the foamed resin serving as the core material layer are formed into a desired irregular cross-sectional shape by a series of steps. Therefore, it is not necessary to preform only the skin layer by press molding as in the conventional production method, and it is easy to shape a complicated cross-sectional shape, and a long molded product can be easily produced.

Here, in the present invention, the materials and production methods of the fiber reinforced thermoplastic resin sheet, the composition of the foamable and crosslinkable resin composition, the crosslinking method, and the like may be adopted as shown below. it can.

(1) Fiber-reinforced thermoplastic resin sheet (1-1) Thermoplastic resin of fiber-reinforced thermoplastic resin sheet The thermoplastic resin of the fiber-reinforced thermoplastic resin sheet used in the present invention includes polyethylene, polypropylene, and poly- ylene. Examples include vinyl chloride, polystyrene, polyamide, polyethylene terephthalate, polybutylene terephthalate, polycarbonate, polyvinylidene fluoride, polyphenylene sulfide, polyphenylene oxide, polyether sulfone, polyether ether ketone, and polymethyl methacrylate.

Further, copolymers, graft resins and blend resins containing the above-mentioned thermoplastic resin as a main component, for example, chlorinated polyvinyl chloride, ethylene-vinyl chloride copolymer, vinyl acetate-ethylene copolymer, vinyl acetate Vinyl chloride copolymer, urethane-vinyl chloride copolymer, acrylonitrile-butadiene-styrene copolymer, acrylonitrile-styrene copolymer, silane-modified polyethylene, acrylic acid-modified polypropylene, maleic acid-modified polyethylene, and the like can also be used. Further, a thermoplastic elastomer or a crosslinked thermoplastic resin can be used.

[0011] Of the above resins, considering the molding temperature, polyethylene, polypropylene, polyvinyl chloride, polystyrene, chlorinated polyvinyl chloride, and ethylene-polypropylene can be molded at a relatively low temperature of 120 to 250 ° C.
Vinyl chloride copolymer, vinyl acetate-ethylene copolymer,
Preferred are vinyl acetate-vinyl chloride copolymer, urethane-vinyl chloride copolymer, acrylonitrile-butadiene-styrene copolymer, and acrylonitrile-styrene copolymer.

The thermoplastic resin used in the fiber-reinforced thermoplastic resin sheet of the present invention may be used alone or in combination. In addition, organic tin malate polymers such as dibutyltin malate polymer, dibutyltin bis (monoalkylmalate), dibutyltin laurate, and organic tin laurate such as monobutyl fatty acid salt, as long as the physical properties are not impaired,
Heat stabilizers such as dioctyltin sulfide, organic tin mercapto such as dibutyltin 3 mercaptopropionate, lead salts such as tribasic lead sulfate and basic lead sulfite, calcium stearate, and metal soap such as lead stearate;
Lubricants such as fatty acid ester wax, low molecular weight polyethylene wax, metal soap, polyhydric alcohol, aliphatic alcohol and fatty acid amide; processing aids such as acrylic resin and olefin resin; plasticizers such as dibutyl phthalate and dioctyl phthalate; Inhibitors, UV absorbers,
Additives such as modifiers and colorants, and fillers such as talc, mica, calcium carbonate, wood powder, synthetic resin ground powder, and fiber-reinforced synthetic resin ground powder may be blended.

(1-2) Fibers of Fiber-Reinforced Thermoplastic Resin Sheet As the fibers of the fiber-reinforced thermoplastic resin sheet used in the present invention, those which do not melt soften and carbonize due to the heat applied in the production process of the present invention can be used. Specifically, glass fibers, carbon fibers, silicon / titanium / carbon fibers, boron fibers, fine metal fibers, or organic fibers such as aramid fibers, polyester fibers, polyamide fibers, natural fibers such as silk, cotton, hemp, etc. Fibers can be mentioned,
Considering strength and cost, glass fibers and carbon fibers are preferred. The diameter of the filament is 1 to 50 μm, especially 3 to
It is preferably 23 μm. When the diameter of the filament is smaller than 1 μm, the reinforcing effect by the fiber is small.
On the other hand, if it is larger than 50 μm, the contact area between the thermoplastic resin and the fiber is smaller than that of a small-diameter fiber of the same type and the same weight, so that the reinforcing effect by the fiber is small.

The content of fibers in the fiber-reinforced thermoplastic resin sheet used in the present invention is in the range of 5 to 80% by weight, and particularly preferably 10 to 50% by weight. If the fiber content is less than 5%, the reinforcing effect is small, and if it exceeds 80% by weight, the resin binding between the fibers is small, so that the fiber-reinforced thermoplastic resin sheet is rather weak.

The length of the fibers in the fiber-reinforced thermoplastic resin sheet is preferably at least 3 mm, and more preferably continuous fibers. The longer the reinforcing fiber, the stronger the strength of the finally obtained fiber reinforced resin foam, and the smaller the fiber length is less than 3 mm, the smaller the reinforcing effect. In addition, in order to shape the fiber-reinforced thermoplastic resin sheet while extending it, the reinforcing fibers are preferably oriented in the longitudinal direction of the product. That is, it is most preferable that the continuous fibers are oriented in the product longitudinal direction.

(1-3) Thickness of fiber-reinforced thermoplastic resin sheet The thickness of the fiber-reinforced thermoplastic resin sheet used in the present invention is as follows:
0.1 to 10 mm, preferably 0.3 to 2 m
m is more preferable. When the sheet thickness is less than 0.1 mm, the strength of the obtained fiber-reinforced resin foam becomes weak, and when the sheet thickness is more than 10 mm, the effect of weight reduction by the core material layer is lost.

Also, in the manufacturing process, if the thickness of the fiber-reinforced thermoplastic resin sheet is less than 0.1 mm, the strength of the fiber-reinforced thermoplastic resin sheet becomes weak, and the tensile strength required at the time of manufacturing cannot be obtained. If it is thicker, shaping into a hollow body becomes difficult.

(1-4) Method for Producing Fiber-Reinforced Thermoplastic Resin Sheet The method for producing the fiber-reinforced thermoplastic resin sheet used in the present invention is not particularly limited, but the following method can be employed as an example. .

After breaking the continuous reinforcing fiber bundle into filaments and aligning them in one direction, a film made of a thermoplastic resin is overlaid and passed between heated pinch rolls, and the molten thermoplastic resin is placed between the filaments of the reinforcing fibers. It is impregnated and cooled by passing through a cooling roll or the like to obtain a fiber-reinforced thermoplastic resin sheet having a desired thickness.

As another method, a continuous reinforcing fiber bundle which is aligned in one direction is drawn into a tank in which a powdery thermoplastic resin is flowing, and while the reinforcing fibers are broken into filaments, After attaching the thermoplastic resin, a method of passing a heated pinch roll, melting the thermoplastic resin, infiltrating between filaments, cooling with a cooling roll or the like, and obtaining a fiber-reinforced thermoplastic resin sheet may be mentioned. it can.

In order to obtain a fiber-reinforced thermoplastic resin sheet in which fibers are arranged in a random state, the reinforcing fibers to which the powdery thermoplastic resin obtained as described above is adhered are rotated with a rotary cutter. Shredded and dropped on the endless belt, accumulated, pressed another endless belt from above, pressurized while sandwiching between upper and lower endless belts, passed through the heating furnace, and cut between the filaments of the shredded reinforcing fibers. , A molten thermoplastic resin is infiltrated into the resin and then passed through a cooling guide roll to obtain a fiber-reinforced thermoplastic resin sheet having a desired thickness.

The fiber reinforced thermoplastic resin sheet used in the present invention may be a single layer or a laminate of a plurality of layers. (2) Foamable and crosslinkable resin composition The foamable and crosslinkable resin composition used in the present invention may be either a thermosetting resin or a thermoplastic resin, each of which will be described below.

(2-1) When a Thermosetting Resin is Used as the Foamable and Crosslinkable Resin Composition As the crosslinkable resin, one that is blended so as to be crosslinked after or during foaming can be used. . That is, A. Compounded so as to be crosslinked (cured or vulcanized) at a temperature higher than the foaming temperature. Those compounded so as to be crosslinked (cured or vulcanized) by means other than heating can be used.

(2-1-1) Thermosetting Resin of Foamable and Crosslinkable Resin Composition The thermosetting resin used for the foamable and crosslinkable resin composition includes a resin which forms a crosslinked structure by heating. All of the mixtures of the compounds exhibiting foaming properties can be used. Specific examples of the thermosetting resin in this case include an epoxy resin, a phenol resin, an unsaturated polyester resin,
Vinyl ester resin, polyurethane resin, urea resin,
Examples include polyacrylic resin, foamable rubber, diaryl phthalate resin, melamine resin, and polyimide resin.

Among these, phenol resins which can be applied to the process easily because the time during which the resin has an elongational viscosity suitable for foaming (curing reaction time) can be relatively long,
It is more preferable to use a polyurethane resin, a foamable rubber, or the like.

In order to impart foaming properties, an organic decomposition foaming agent such as azodicarbonamide and a physical foaming agent such as Freon, ethanol and methylene chloride may be mixed, or Low molecular weight substances generated during the curing process, such as water vapor of a phenol resin and carbon dioxide of a polyurethane resin using a polyol containing water, can also be used.

Further, in order to optimize bubbles, a foam stabilizer such as polysiloxane-polyoxylen block copolymer, a surfactant, and a foaming agent such as calcium carbonate may be added to the above-mentioned resin.

(2-1-2) Foaming Agent for Foamable and Crosslinkable Resin Composition As the foaming agent used for the foamable and crosslinkable resin composition, decomposition foaming which chemically decomposes by heat to generate gas is used. An agent and a volatile foaming agent utilizing gasification of a volatile liquid can be used. As described above, it is also possible to use water vapor and carbon dioxide, which are low molecular weight substances generated in the curing reaction process.

Examples of the decomposable foaming agent include azodicarbonamide, azobisisobutyronitrile, N, N'-dinitrosopentamethylenetetramine, p, p'-oxybisbenzenesulfonyl human azide, barium azodicarboxylate, Hydrazinotriazine, p-toluenesulfonyl hydrazide, sodium bicarbonate, ammonium carbonate and the like.

Examples of the volatile foaming agent include aliphatic hydrocarbons such as propane, butane, pentane, hexane and heptane; chlorinated aliphatic hydrocarbons such as methyl chloride and methylene dichloride; and 1,1-dichloro-1-fluoro. Ethane, 2,
2-dichloro-1,1,1-trifluoroethane, 1,
Freon gas such as 1,1,2-tetrafluoroethane is exemplified.

Here, the amount of the foaming agent to be added to the resin must be appropriately adjusted because the amount of gas generated varies depending on the foaming agent and the type of reaction.
It is preferable to mix in an amount of 0.5 to 15 parts by weight with respect to 00 parts by weight. If the amount of the foaming agent is too small, a foamed molded product cannot be obtained, and if the amount of the foaming agent is too large, the cells break and the dense cells cannot be obtained. For example, when manufacturing a resin foam having an expansion ratio of 10 times using azodicarbonamide, 5 to 5 parts by weight of the resin is used.
It is appropriate to use 7.5 parts by weight.

(2-1-3) Composition Combined to Crosslink in the Curing Reaction Process As a specific example, the resin was foamed and shaped into a resin that generates a low molecular weight gas before the curing reaction was completed. Thereafter, a method of completing the crosslinking (curing) may be mentioned.

This method includes condensed water in the case of a phenol resin, and carbon dioxide resulting from the reaction of water and isocyanate contained in a polyol in the case of a polyurethane resin.

Further, it is also possible to carry out foaming with the above-mentioned decomposable foaming agent at a temperature lower than the temperature at which the curing reaction is performed, and to further cure (vulcanize). As a method of obtaining a foamable and crosslinkable resin composition, a crosslinkable resin as a main material, a foaming agent,
If necessary, there can be mentioned a method in which auxiliary materials such as a crosslinking aid and other heat stabilizers, lubricants and fillers described above are blended by a mixing device such as a kneader.

In the present invention, the foamable and crosslinkable resin composition thus obtained is preferably in the form of pellets or powder in order to be held in a fiber bundle composed of a large number of continuous monofilaments. In order to uniformly disperse it in the powder, it is particularly preferable to make the powder.

When a two-component resin such as a polyurethane resin is used, the two components are mixed, then sprinkled on a fiber bundle composed of continuous monofilaments, and the fiber bundle is sandwiched between bars or plates, rubbed, etc. Is dispersed uniformly in the fiber bundle.

(2-1-4) Expansion Ratio of Expandable and Crosslinkable Resin Composition The expansion ratio of the expandable and crosslinkable resin composition in the present invention is determined based on the strength and specific gravity required for a manufactured product. Although it is appropriately selected depending on the type of the resin, a range of 1.2 to 20 times is preferable, and a range of 2 to 10 times is particularly preferable. If the expansion ratio is less than 1.2 times, the effect of reducing the weight by foaming is small, and if the expansion ratio exceeds 20 times, the strength becomes very weak.

(2-2) When a Thermoplastic Resin is Used as the Foamable and Crosslinkable Resin Composition As the crosslinkable resin, those which are blended so as to be crosslinked after foaming or while foaming can be used. That is, A. Compounded so as to crosslink at a temperature higher than the foaming temperature. Those compounded so as to be crosslinked by means other than heating can be used.

(2-2-1) Thermoplastic resin of foamable and crosslinkable resin composition The thermoplastic resin used for the foamable and crosslinkable resin composition in the present invention is a fiber-reinforced thermoplastic resin sheet. The same thermoplastic resin as that used can be used, but it is preferable to use a thermoplastic resin that can be heat-fused with the thermoplastic resin used for the fiber-reinforced thermoplastic resin sheet.

Specifically, it is preferable to use the same type of thermoplastic resin (a thermoplastic resin polymerized from the same monomer). As a combination when using different types of thermoplastic resins, for example, polyethylene and polypropylene, polyethylene and vinyl acetate-ethylene copolymer, polyethylene and chlorinated polyethylene, polystyrene and acrylonitrile-butadiene-styrene copolymer, polystyrene and Acrylonitrile-styrene copolymer, polyvinyl chloride and chlorinated polyvinyl chloride, polyvinyl chloride and ethylene-vinyl chloride copolymer, polyvinyl chloride and vinyl acetate-vinyl chloride copolymer, polyvinyl chloride and urethane-vinyl chloride Copolymer, polyvinyl chloride and polymethyl methacrylate, polyvinyl chloride and acrylonitrile-butadiene-styrene copolymer, polybutylene terephthalate and polyethylene terephthalate, acrylonitrile-butadiene-styrene Polymer and an acrylonitrile - styrene copolymer. Further, a combination of a thermoplastic resin and the same type of modified thermoplastic resin can also be used. Examples of this include polyethylene and silane-modified polyethylene, polyethylene and acrylic acid-modified polypropylene, and polyethylene and maleic acid-modified polyethylene.

(2-2-2) Foaming Agent for Foamable and Crosslinkable Resin Composition The foaming agent used for the foamable and crosslinkable thermoplastic resin composition is a decomposition agent which is chemically decomposed by heat to generate gas. A foaming agent and a volatile foaming agent utilizing gasification of a volatile liquid can be used.

Examples of the decomposable foaming agent include azodicarbonamide, azobisisobutyronitrile, N, N'-dinitrosopentamethylenetetramine, p, p'-oxybisbenzenesulfonylhydrazide, barium azodicarboxylate, and trihydra. Dinotriazine, p-toluenesulfonyl hydrazide, sodium bicarbonate, ammonium carbonate and the like.

Examples of the volatile foaming agent include aliphatic hydrocarbons such as propane, butane, pentane, hexane and heptane; chlorinated aliphatic hydrocarbons such as methyl chloride and methylene dichloride; and 1,1-dichloro-1-fluoro. Ethane, 2,
2-dichloro-1,1,1-trifluoroethane, 1,
Freon gas such as 1,1,2-tetrafluoroethane and the like can be mentioned.

The amount of the foaming agent to be mixed with the resin must be appropriately adjusted since the amount of gas generated varies depending on the type of the foaming agent.
It is preferable to mix in a range of 0.5 to 15 parts by weight with respect to 0 parts by weight. If the amount of the foaming agent is too small, a foamed molded article cannot be obtained, and if the amount of the foaming agent is too large, cells break and foam cells cannot be obtained. For example, when producing a thermoplastic resin foam having a foaming ratio of 10 times using azodicarbonamide, the amount is suitably 5-7.5 parts by weight.

(2-2-3) About a resin composition blended so as to be crosslinked at a temperature higher than the foaming temperature As a specific example, an organic peroxide having a decomposition temperature higher than the decomposition temperature of the foaming agent contained is blended. Then, after foaming and shaping, a method of cross-linking by free radicals generated by the decomposition of the organic peroxide may be mentioned.

The method includes dicumyl peroxide,
Dibutyl peroxide and 2,5-dimethyl-2,5-
Organic peroxides such as di (t-butylperoxy) hexane can be used.

If necessary, a crosslinking assistant such as a monomer having a polyfunctional group such as divinylbenzene or triallyl cyanurate or an oxime / nitroso compound such as quinone dioxime or benzoquinone dioxime is used.
Crosslinking may be promoted.

As a combination of a blowing agent and an organic peroxide which can be used in this method, for example, when azodicarbonamide is used as the blowing agent, diisopropylbenzene hydroperoxide or methane hydroperoxide may be used as the organic peroxide. And the like. When sodium bicarbonate is used as the foaming agent, the organic peroxide is preferably dicumyl peroxide or di-t-butyl peroxide.

As a method of obtaining a foamable and crosslinkable resin composition having such a composition, a foaming agent, a peroxide, a crosslinking assistant if necessary, and other additives described above are added to a thermoplastic resin as a main material. A method in which the auxiliary materials such as the heat stabilizer, the lubricant and the filler are mixed with a stirring device such as a mixer or a tumbler can be adopted.

In the present invention, as described above, since the foamable and crosslinkable resin composition is held in a plurality of fiber bundles composed of a large number of continuous monofilaments, the composition is in the form of pellets or powder. Preferably,
In order to disperse uniformly in the filament, it is more preferable to make the powder.

(2-2-4) Regarding a resin composition blended so as to be crosslinked by means other than heating..1 As a specific example, a method of foaming and shaping, followed by crosslinking with an electron beam. No.

Electron beam crosslinking refers to cross-linking by irradiating a shaped fiber reinforced resin foam with an electron beam. When electron beam alone is insufficient for crosslinking (in the case of a degradable resin), The above-mentioned organic peroxides and crosslinking assistants may be blended.

As a method for obtaining such a foamable and crosslinkable resin composition, as in the case of the above-mentioned composition (2-2-3), a foaming agent, an organic peroxide compounded as necessary, It is obtained by blending with the main material or further processing into pellets or the like so that the crosslinking assistant is not decomposed.

(2-2-5) Regarding the resin composition blended so as to be crosslinked by means other than heating..2 As a specific example of the crosslinking method other than the electron beam crosslinking regardless of heating, water is used. A method of foaming a composition using a thermoplastic resin modified to be crosslinkable, shaping the mixture, and then boiling the mixture to carry out crosslinking.

The thermoplastic resin modified to be water-crosslinkable is
This is a thermoplastic resin obtained by heating and kneading an organic peroxide and a silane coupling agent such as vinyltrimethoxysilane and vinyltriethoxysilane into a thermoplastic resin and grafting with silane, and crosslinking by water treatment. Here, the water treatment is a treatment such as humidification, immersion in steam or hot water.

As a method for obtaining such a foamable and crosslinkable resin composition, a water-crosslinkable thermoplastic resin is obtained by blending or processing into a pellet or the like in a state where moisture is controlled so as not to crosslink. Can be

(2-2-6) Expansion ratio of expandable and crosslinkable thermoplastic resin composition The expansion ratio of the expandable and crosslinkable resin composition containing a thermoplastic resin as a main component is required for the product to be manufactured. It is selected as appropriate depending on the strength, specific gravity, type of resin used, etc.
A range of 1.2 to 20 times is preferable, and a range of 2 to 10 times is particularly preferable. When the expansion ratio is less than 1.2 times, the effect of reducing the weight by foaming is poor, and the expansion ratio is 2 times.
If it exceeds 0 times, the strength becomes very weak.

(3) Fiber Bundle Holding Foamable and Crosslinkable Resin Composition In the method of the present invention, the foamable and crosslinkable resin composition is held on a plurality of fiber bundles composed of a large number of continuous monofilaments. The fiber-reinforced thermoplastic resin sheet is guided into a shaped hollow body, but the type of the fiber constituting the holding fiber bundle is not particularly limited, and specifically, the fiber-reinforced thermoplastic resin described above is used. Examples thereof include those equivalent to the reinforcing fibers used for the sheet.

(4) Production of Fiber Reinforced Resin Foam (4-1) Shaping of Fiber Reinforced Thermoplastic Resin Sheet into Hollow Body The “hollow body” as referred to in the present invention refers to the ends of sheets. Are abutted or superimposed, for example, what is shaped into a cylindrical shape with a circular or square cross section, and this `` hollow body '' has a slight gap between the ends of the sheet The state that has occurred is also included.

As a method of shaping the fiber reinforced thermoplastic resin sheet into a hollow body, a method of gradually bending the sheet using a synthetic resin shoe or roll can be used. When shaping into a hollow body, it is preferable to heat the sheet with a far-infrared heater, a hot air blower, or the like to prevent the sheet from cracking or tearing, while shaping the thermoplastic resin in a softened state. Further, as another method of shaping the sheet into a hollow body, a mold provided with a sheet passage having a shape such that the sheet is gradually bent and shaped into the hollow body is used. A method of guiding the sheet into the sheet passage can be adopted.

Here, the above-mentioned softened state is defined as JIS-
A state in which the thermoplastic resin is heated to a temperature equal to or higher than the Vicat softening temperature measured according to K-7206. Generally, it refers to a state in which the thermoplastic resin starts to deform and is heated to a temperature at which the mechanical properties decrease.

The fiber-reinforced thermoplastic resin sheet may be shaped into a hollow body by using only one sheet, or a plurality of sheets may be used to form one hollow body as a whole. You may. When a plurality of sheets are used to form one hollow body, the sheets may be abutted against each other, or the respective ends may be overlapped.

(4-2) A method of supplying a resin composition into a hollow body and a method of foaming when a thermosetting resin is used as the foamable and crosslinkable resin composition. A liquid crosslinkable resin is used. In this case, the liquid mixture composition is dropped on a fiber bundle, sandwiched between bars or plates, uniformly dispersed in the fiber bundle by an operation such as rubbing, and introduced into the hollow body as a resin-adhered fiber bundle.

When a pellet or powdered crosslinkable resin is used, the mixed composition is sprinkled on a fiber bundle, sandwiched between bars or plates, and uniformly rubbed into the fiber bundle by an operation such as rubbing. It is dispersed and introduced into the hollow body as a resin-attached fiber bundle.

As a method of foaming the foamable and crosslinkable resin composition, a method of inserting the composition into a mold heated to a high temperature,
Examples include a method of blowing hot air into the hollow body, and when the mixed composition is in the form of pellets or powder,
When hot air is blown into the inside, the mixed composition scatters and causes unevenness. Therefore, it is preferable to employ a method of inserting the mixed composition into a mold heated to a high temperature.

(4-3) Crosslinking Method of Expanded Crosslinkable Resin Composition When Thermosetting Resin is Used as Foamable and Crosslinkable Resin Composition After foaming, a further curing reaction (crosslinking reaction) is performed. If it is necessary to complete the process, use a heating furnace to heat the shaping mold heated to a high temperature to lengthen the heating time by increasing the length of the shaping mold, or to a temperature below the shaping temperature of the fiber-reinforced thermoplastic resin sheet on the surface. Can be adopted.

(4-4) Supply of resin composition and foaming method when thermoplastic resin is used for foamable and crosslinkable resin composition When thermoplastic resin is used, pellet-like or powder-form mixing A method can be employed in which the composition is sprinkled on a fiber bundle, uniformly dispersed in the fiber bundle by an operation such as rubbing, and introduced into a hollow body as a resin-adhered fiber bundle.

As a method of foaming the resin composition, as in the case of the thermosetting resin, a method of inserting the resin composition into a mold heated to a high temperature, a method of blowing hot air into a hollow body, and the like can be mentioned. When the powder is in the form of pellets or powder, the mixed composition is scattered and causes non-uniformity. Therefore, it is preferable to adopt a method of inserting the mixture into a mold heated to a high temperature.

(4-5) Method of crosslinking foamed crosslinkable resin composition when thermoplastic resin is used as foamable and crosslinkable resin composition: peroxide as described in (2-2-3) above In the method of cross-linking by free radicals generated by decomposition of the resin, the foamable and cross-linkable resin composition is foamed, the hollow body is shaped into a desired cross-sectional shape, and then heated to a temperature at which peroxide is decomposed. Thereby, crosslinking is performed.

In the case where electron beam crosslinking is employed as in (2-2-4), the foamable and crosslinkable resin composition is foamed, and the hollow body is shaped into a desired sectional shape. rear,
Irradiation with an electron beam generates free radicals to effect crosslinking.

Further, in the method of crosslinking using a water-crosslinkable resin as described in the above (2-2-5), the foamable and crosslinkable resin composition is foamed, and the hollow body is formed into a desired sectional shape. After shaping, crosslinking is performed by performing a water treatment.

(4-6) Forming of Hollow Body into Desired Cross-sectional Shape by Foaming Pressure In the present invention, the hollow fiber-reinforced thermoplastic resin sheet is foamable and crosslinked inside. By forming the outer periphery along the regulating member by the foaming pressure of the conductive resin composition, a desired cross-sectional shape is formed. At this time, it is preferable that the fiber-reinforced thermoplastic resin sheet has a softening temperature or higher.

As a method for softening the fiber-reinforced thermoplastic resin sheet, there is a method of heating a regulating member for regulating the outer periphery, that is, a mold or a jig to a temperature higher than the softening temperature of the thermoplastic resin by a heater. Can be

Examples of the method of shaping the hollow body in the softened state include a method in which the hollow body is inserted into a mold and pressed against the inner surface of the mold with the foaming pressure of the foamable and crosslinkable resin composition. When shaping is performed in a mold, the shaping may be assisted by evacuating the inside or using compressed air.

Here, in the present invention, the basis is that the outer periphery of the hollow body is pressed against the regulating member by the foaming pressure generated from the foamable and crosslinkable resin composition.
When only the foaming pressure of the foamable and crosslinkable resin composition is not sufficient to press the hollow body against the regulating member, pressure may be separately applied to the inside of the hollow body. It is preferable to use a regulating member having a structure capable of supplying air to the inside of the hollow body by providing an air pipe through the inside of the regulating member.

When shaping the hollow body into a desired cross-sectional shape by foaming pressure, it is also possible to shape the hollow body while expanding it. That is, it is also possible to shape the molded article so that the outer peripheral length of the molded article is longer than the outer peripheral length of the hollow body.

The cross-sectional shape of the molded product can be arbitrarily selected, but the stretch ratio defined as follows is preferably as small as possible. The stretching ratio is (thickness of the fiber-reinforced thermoplastic resin sheet before spreading) / (thickness of the fiber-reinforced thermoplastic resin sheet after spreading). The stretching of the fiber-reinforced thermoplastic resin sheet depends on the type of the thermoplastic resin, the thickness of the fiber-reinforced thermoplastic resin sheet, and the temperature at the time of spreading, but the thickness of the fiber-reinforced thermoplastic resin layer of the molded product is 0.1 mm or more. It is preferable to set the magnification so that When the thickness is less than 0.1 mm, the strength of the molded article becomes weak, and the fiber-reinforced thermoplastic resin layer (sheet) may be broken during molding.

[0078]

EXAMPLES Examples in which a fiber-reinforced resin foam was actually produced by employing the production method of the present invention will be described below with reference to cited examples.

Example 1 Production of Fiber Reinforced Thermoplastic Resin Sheet As shown in FIG. 1, an apparatus for producing a fiber reinforced thermoplastic resin sheet includes a reinforcing fiber bundle feeding machine 11 and a resin flow tank 12. , A heating pinch roll 13, a cooling pinch roll 14, a take-up roll 15, and a winder 16.

The glass fiber bundle 1 (glass roving, manufactured by Nitto Boseki Co., Ltd., 4
400 tex, a fiber diameter of 23 μm) are drawn together, and the powdered polypropylene 2 (pulverized to a melt flow rate of 30 and an average particle diameter of 100 μm) is drawn into the resin flowing tank 12 flowing by air, and the glass The powdery polypropylene 2 was adhered while the fiber bundle 1 was unwound in filament units. In a state where the glass fiber bundles to which the polypropylene is attached are arranged in a plane, the glass fiber bundles are heated while being pressed to 10 kg / cm ² by a heating pinch roll 13 heated to 220 ° C., and the polypropylene is melted to form a gap between the glass fibers. Infiltrated. Subsequently, it is cooled by a cooling pinch roll 14, trimmed to a width of 100 mm, taken up by a take-off machine 15, and taken out of a 0.4 mm-thick glass fiber reinforced polypropylene sheet (hereinafter, the sheet thus obtained is referred to as a fiber reinforced sheet A). ) Was wound up on a winder 16.

Blending of foamable and crosslinkable resin composition The foamable and crosslinkable resin composition is obtained by pulverizing the polyethylene resin shown in Table 1 to a particle size of about 100 μm, and then adding a blowing agent, an organic peroxide, and a crosslinking aid. The foaming and crosslinkable resin composition obtained in this manner was obtained by mixing the agents in a mixing ratio shown in the same table with a mixer (hereinafter referred to as a powdery resin composition B).

[0082]

[Table 1]

Apparatus for Producing Fiber-Reinforced Resin Foam A production apparatus used in Example 1 is shown in a schematic sectional view in FIG. This apparatus includes a reinforcing fiber bundle feeding machine 21, a fiber reinforced sheet feeding machine 22, a powdery resin spraying device 23,
The main components are a rubbing bar device 24, a preheating mold 25, a shaping mold 26, a heating mold 27, a cooling mold 28, and a product take-up machine 29.

The three reinforcing fiber bundles 3 are fed out from the reinforcing fiber bundle feeding machine 21, each of which is disassembled into filaments and aligned, and the powdery resin 4 is supplied from the powdery resin dispersion device 23 from above. At the same time, the powdered resin 4 is rubbed by the rubbing bar 24 so that the powdered resin 4 is uniformly dispersed between the filaments of the reinforcing fiber bundle 3, and the fiber reinforced thermoplastic resin sheet 5 is formed into a hollow body around the bar. The resin was supplied while being shaped, and the resin-attached fiber bundle 3 'was wrapped by the hollow body 5'. Here, the falling objects of the powdery resin 4 are collected or the fiber reinforced thermoplastic resin sheet 3 is collected.
I dropped it up.

The preheating mold 25 has a passage through which the fiber-reinforced thermoplastic resin sheet 5 passes, and the cross-sectional shape of the sheet passage is U-shaped at an upstream end which is an insertion portion of the sheet 5. As the fiber reinforced thermoplastic resin sheet 5 passes through the preheating mold 25, the sheet 5 has its ends (side edges) projecting toward each other. It is formed into a hollow body 5 ′ having a diameter of 31.8 mm and a perfect circle in cross section.

The cross-sectional shape of the shaping mold 26 is a circle having a diameter of 31.8 mm at a contact portion with the preheating mold 25, which is the upstream end, and gradually deforms toward the downstream side. Thus, the outlet at the downstream end has an irregular shape as shown in FIG. The sectional shapes of the heating mold 27 and the cooling mold 28 are uniform from upstream to downstream, and are the same as the sectional shape of the shaping mold 26 shown in FIG.

Production of Fiber Reinforced Resin Foam A glass fiber bundle (glass roving manufactured by Nitto Boseki Co., Ltd., 4400 tex, fiber diameter 23 μm) was used as the reinforcing fiber bundle 3, and the above-mentioned powdery resin composition was used as the powdery resin 4. B was used. Further, the fiber reinforced sheet A as the fiber reinforced thermoplastic resin sheet 5 was inserted into the preheating mold 25 heated to 200 ° C., and the cylindrical hollow body was gradually formed in a softened state of the resin. After shaping the reinforcing fiber bundle 3 'with the powdered resin composition B attached from the periphery thereof while shaping it into 5', it is introduced into the shaping mold 26 and the heating mold 27 heated to 220 ° C. did.

The powdered resin composition B was mixed with the preheated mold 25
Starts foaming in the hollow body 5 'in the molding die 2
6, the inside of the hollow body 5 ′ is filled, and the foaming pressure generates a foaming pressure enough to press the outer periphery of the hollow body 5 ′ against the shaping mold 26, thereby forming the hollow body 5 ′. Together with the foamed resin therein, it was gradually shaped into a cross-sectionally irregular shape in the shaping mold 26. In the shaping mold 26 and the subsequent heating mold 27, the organic peroxide blended in the composition B was decomposed to crosslink the foamed resin layer made of the composition B.

Thereafter, the whole is cooled by a cooling mold 28, as shown in a schematic sectional view of FIG.
Thus, a fiber-reinforced resin foam 6 in which the periphery of No. 1 was covered with a fiber-reinforced thermoplastic resin layer 62 was obtained.

Example 2 Production of Fiber Reinforced Thermoplastic Resin Sheet The same as in Example 1 was performed.

Formulation of Foamable and Crosslinkable Resin Composition The foamable and crosslinkable resin composition used in Example 2 had the formulation shown in Table 2. However,
These were impact-mixed immediately before being discharged to the reinforcing fiber bundle 3 as described later (hereinafter, the blended composition is referred to as a resin composition C, and the components before blending are referred to as compositions C-1 and C-2. Name).

[0092]

[Table 2]

Apparatus for Producing Fiber Reinforced Resin Foam The apparatus used in Example 2 is almost the same as that shown in FIG.
A discharge injection machine and a discharge nozzle communicating therewith were arranged, and the rest was the same as FIG.

Production of Fiber-Reinforced Resin Foam The reinforcing fiber bundle 3 was the same as in Example 1, and
The composition C in which the compositions C-1 and C-2 were collision-mixed by a discharge injection machine was discharged through a discharge nozzle, and was uniformly dispersed by a rubbing bar 24.

The fiber-reinforced thermoplastic resin sheet 5 was obtained in Example 1.
In the same manner as in the above, a fiber reinforced sheet A is used.
5, the shaping mold 26 and the heating mold 27 are each 20
Heated to 0 ° C., wrapped the reinforcing fiber bundle 3 ′ holding the resin composition C by shaping into a hollow body 5 ′ in the same procedure as in Example 1, and immersing the resin composition in the hollow body 5 ′. C is foamed, the outer periphery of the hollow body 5 ′ is pressed against the shaping mold 26 by the foaming pressure, shaped into the same cross-sectional shape as in Example 1, and heated by the heating mold 27. By cooling with the cooling mold 28, a fiber reinforced resin foam having the same structure as that shown in FIG. 4 was obtained.

<Comparative Example> Production of Fiber Reinforced Thermoplastic Resin Sheet Using the same materials and equipment as in Example 1, a width of 120 mm was used.
Was obtained (hereinafter, referred to as fiber-reinforced sheet D).

Production of foam layer Glass fiber bundle (glass roving 440 manufactured by Nitto Boseki Co., Ltd.)
(0 tex, fiber diameter 23 μm) In a state where three filaments are unraveled into filaments and aligned, from above, [Table 1] of Example 1
The powdered resin composition B having the composition shown in (1) was sprayed and rubbed so that the composition B was uniformly dispersed, and then the shaping mold 26 and the heating mold in FIG. Type 2
7, and introduced into a group of molds having the same cross-sectional shape as the cooling mold 28, foamed, crosslinked, cooled, and have a modified cross-sectional shape equivalent to the mold shape shown in FIG. 3m
Was obtained.

Production of Fiber-Reinforced Resin Foam The fiber-reinforced sheet D obtained in the above was bonded to the outer peripheral surface of the pre-foamed molded article obtained above. That is, the fiber-reinforced sheet D is cut into a length of 3 m, a chlorinated polyethylene adhesive is applied to one surface thereof, and the fiber-reinforced sheet D is adhered along the outer peripheral surface of the pre-foamed molded product, thereby obtaining a material equivalent to that obtained in each example. Thus, a fiber reinforced resin foam having the following structure was obtained.

The operation of laminating the fiber reinforced sheet D to the pre-foamed molded article was extremely difficult because the length was as long as 3 m.

[0100]

As described above, according to the present invention, a plurality of fiber bundles composed of a large number of monofilaments are used as a holding carrier, and a foamable and crosslinkable resin composition is held on the holding carrier.
While the whole is wrapped in a hollow body formed by shaping a fiber reinforced thermoplastic resin sheet, a foamable and crosslinkable resin composition is foamed inside the hollow body, and the hollow body is regulated by the foaming pressure. Since the cross-linkable resin composition foamed during or after the shaping is formed into a desired cross-sectional shape along the member and the foamed cross-linkable resin composition is crosslinked, the fiber reinforced layer can be formed without a conventional preforming step. Since the (skin layer) and the foam layer (core layer) can be formed at once, it is possible to efficiently and easily manufacture a long fiber-reinforced resin foam using a relatively simple process. This is particularly useful when trying to obtain a long molded body having a complicated cross-sectional shape. In addition, since the foamed layer is crosslinked after or during foaming to form a three-dimensional network structure, the resulting fiber-reinforced resin foam has excellent mechanical strength. Further, in the fiber-reinforced resin foam obtained in the present invention, the fiber bundle for holding the foamable and crosslinkable resin composition is in a state of being dispersed in the foamed resin layer, and this fiber bundle is also formed of the fiber-reinforced resin foam. Helps improve the mechanical strength of the body.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of an apparatus for manufacturing a fiber-reinforced thermoplastic resin sheet used in each embodiment of the present invention.

FIG. 2 is a schematic cross-sectional view showing a configuration of an apparatus for manufacturing a fiber-reinforced resin foam used in Example 1 of the present invention.

FIG. 3 is an explanatory view of a vertical cross-sectional shape at an outlet portion of a shaping mold 26 in FIG. 2;

FIG. 4 is a schematic sectional view showing the structure of a fiber-reinforced resin foam obtained in each example of the present invention.

[Explanation of symbols]

 Reference Signs List 3 reinforcing fiber bundle 4 powdery foamable and crosslinkable resin composition 5 fiber-reinforced thermoplastic resin sheet 5 ′ hollow body 6 fiber-reinforced resin foam 61 foamed resin layer 62 fiber-reinforced thermoplastic resin layer 21 reinforcing fiber bundle Feeding machine 22 Fiber reinforced sheet feeding machine 23 Powder resin dispersion device 23 24 Bar rubbing device 24 25 Preheating mold 26 Shaping mold 27 Heating mold 28 Cooling mold 29 Product take-off machine 29

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code FI B29L 23:00

Claims (1)

[Claims] Claims: 1. A foamable and crosslinkable resin composition is held in a plurality of fiber bundles composed of a large number of continuous monofilaments,
One or more fiber-reinforced thermoplastic resin sheets are continuously supplied into the hollow body while being formed into a hollow body, and the fiber bundle holding the composition is wrapped around the sheet, and the foaming is carried out inside the hollow body. The foamable and crosslinkable resin formed by foaming a water-soluble and crosslinkable resin composition, shaping the hollow body into a desired cross-sectional shape along the regulating member by the foaming pressure, and foaming during or after the shaping. A method for producing a fiber-reinforced resin foam, comprising crosslinking a composition.