JP2020050786A - Foam particle, foam molded body, fiber reinforced composite, and automobile component - Google Patents

Abstract

To provide a foam molded body exhibiting excellent physical property, and a foam particle capable of manufacturing the foam molded body.SOLUTION: There is provided a foam molded body constituted by a substrate resin containing a copolymer of aromatic vinyl, (meth)acrylic acid ester, and unsaturated dicarboxylic acid, constituted by a plurality of foam particles, having small air bubbles with an air bubble diameter of 50 μm or more and less than 300 μm, and large air bubble with an air bubble diameter of 300 μm to 2 mm in a cross section picture photographing an area of 11.9 mmat 30 magnification, in which difference between the average air bubble diameter of the small air bubbles and the average air bubble diameter of the large air bubbles is 1000 μm or more and less than 1500 μm, and the foam particles provide maximum point stress by a flexure test of 1.0 MPa or more to a foam molded body constituted by a fusion body thereof.SELECTED DRAWING: Figure 1

Description

  The present invention relates to expanded particles, expanded molded articles, fiber-reinforced composites, and automotive parts. More specifically, the present invention relates to foamed particles capable of providing a foamed molded article having improved mechanical properties, and a foamed molded article, a fiber-reinforced composite, and an automobile part obtained from the foamed particle.

2. Description of the Related Art In recent years, vehicles such as aircraft, automobiles, and ships have been required to have improved fuel efficiency in order to reduce the impact on the global environment. The flow is getting stronger. As these resin materials, fiber reinforced plastics can be cited, but it is also studied to further reduce the weight and increase the rigidity by partially using a lightweight core material. A polystyrene foam having high compressive strength has been studied as a material used as a lightweight core material.
However, since the polystyrene resin has a low glass transition temperature, its mechanical properties are not sufficient. Therefore, it has been desired to provide a foamed molded article having improved mechanical properties and foamed particles capable of producing the foamed molded article.
Therefore, the applicant of the present application repeated the test on the assumption that the use of another type of resin instead of the polystyrene-based resin would improve the mechanical properties. As a result, he noticed that the use of a copolymer of aromatic vinyl, (meth) acrylic acid ester, and unsaturated dicarboxylic acid as the base resin for the foamed particles could improve the mechanical properties of the foamed molded article to some extent. It has been found that the mechanical properties can be significantly improved by controlling the diameter of the cells constituting the expanded particles while using the base resin (Japanese Patent Application Laid-Open No. 2017-186503: Patent Document 1).

JP 2017-186503 A

However, it is desired to provide a foamed molded article having more excellent mechanical properties than the foamed molded article of Patent Document 1, and a foamed particle capable of producing the foamed molded article.
Therefore, an object of the present invention is to provide a foamed molded article exhibiting excellent mechanical properties and a foamed particle capable of producing the foamed molded article.

  The inventor of the present invention further studied the technique of Patent Document 1, and found that the difference in cell diameter between small bubbles and large cells was larger and within a specific range, whereby a foam molded article obtained from expanded particles was obtained. The present invention has been completed by surprisingly finding that mechanical properties such as the maximum stress in a bending test can be greatly improved.

Thus, according to the present invention, foamed particles composed of a base resin containing a copolymer of an aromatic vinyl, a (meth) acrylic acid ester, and an unsaturated dicarboxylic acid, wherein the foamed particles are 30 times larger in the cross section photograph of an area of 11.9 mm ^2, and a large bubble of the small bubble and less bubble diameter 300 [mu] m or more and 2mm of bubble size less than 50μm or more and 300 [mu] m, an average cell diameter and large bubbles of small bubbles The difference from the average cell diameter of the above is 1000μm or more and less than 1500μm, the foamed particles give a maximum point stress by a bending test of 1.0MPa or more to a foamed molded article formed from the fused body. A foamed particle is provided.
Further, according to the present invention, there is provided a foamed molded product composed of a base resin containing a copolymer of aromatic vinyl, a (meth) acrylate, and an unsaturated dicarboxylic acid, wherein the foamed molded product is In a cross-sectional photograph taken of an area of 11.9 mm ^{2 at} a magnification of 30 times, small bubbles having a bubble diameter of 50 μm or more and less than 300 μm and a bubble diameter of 300 μm or more and 2 mm or less are formed. Wherein the difference between the average cell diameter of the small cells and the average cell diameter of the large cells is 1000 μm or more and less than 1500 μm, and wherein the expanded particles are 1% in the expanded molded article composed of the fused body. A foam molded article characterized by giving a maximum point stress by a bending test of 0.0 MPa or more.
Further, according to the present invention, there is provided a fiber-reinforced composite comprising the above-mentioned foamed molded article and a fiber-reinforced plastic layer laminated and integrated on the surface of the foamed molded article.
Further, according to the present invention, there is provided an automobile part comprising the above-mentioned foamed molded article or fiber-reinforced composite.

ADVANTAGE OF THE INVENTION According to this invention, the foaming molded article which shows excellent mechanical properties, and the foaming particle which can manufacture the foaming molded article can be provided.
Further, in any of the following cases, it is possible to provide a foamed molded article exhibiting more excellent mechanical properties and a foamed particle capable of producing the foamed molded article.
(1) The expanded particles have, in one of them, only one large cell.
(2) Aromatic vinyl is a styrene monomer, (meth) acrylate is (meth) acrylic acid alkyl ester (alkyl group has 1 to 5 carbon atoms), and unsaturated dicarboxylic acid is 2 to 6 carbon atoms. And the copolymer is selected from aliphatic unsaturated dicarboxylic acids, and when the total of the units derived from the aromatic vinyl, the (meth) acrylate ester and the unsaturated dicarboxylic acid is 100 parts by weight, It contains 30 to 80 parts by weight of units derived from vinyl, 8 to 35 parts by weight of units derived from (meth) acrylate, and 10 to 50 parts by weight of units derived from unsaturated dicarboxylic acid.

It is a cross-sectional photograph of the foamed particles and foamed molded products of Examples 1 and 2. 4 is a cross-sectional photograph of the foamed particles and the foamed molded product of Example 3. It is a cross-sectional photograph of the foamed particles and foamed molded products of Examples 4 and 5. It is a cross-sectional photograph of the foamed particles and foamed molded articles of Comparative Examples 1 to 3.

(1) Expanded Particles (1-1) Base Resin The expanded particles are made of a base resin containing a copolymer of aromatic vinyl, (meth) acrylate and unsaturated dicarboxylic acid. The proportion occupied by the copolymer in the base resin is preferably 70% by weight or more, more preferably 85% by weight or more, and may be 100% by weight. Preferably, the copolymer has a glass transition temperature Tg of 115-160C. When Tg is lower than 115 ° C., lamination and integration of the skin material on the surface of the foamed molded article manufactured using the foamed particles may be insufficient, and mechanical properties may be reduced. When the temperature is higher than 160 ° C., the foaming properties of the foamed particles are reduced, and the heat fusion and integration of the foamed particles are insufficient, so that the mechanical properties of the foamed molded article may be reduced. A more preferred Tg is from 120 to 150C.

(A) Aromatic vinyl Aromatic vinyl is an aromatic compound having a substituent consisting of a vinyl group. The number of vinyl groups and the carbon number of the aromatic compound are not particularly limited. Specific aromatic vinyls include styrene, α-methylstyrene, vinyltoluene, ethylstyrene, i-propylstyrene, t-butylstyrene, dimethylstyrene, bromostyrene, chlorostyrene and other styrene-based monofunctional monomers, Divinylbenzene, trivinylbenzene, divinyltoluene, divinylxylene, bis (vinylphenyl) methane, bis (vinylphenyl) ethane, bis (vinylphenyl) propane, bis (vinylphenyl) butane, divinylnaphthalene, divinylanthracene, divinylbiphenyl, Examples include bisphenol A ethylene oxide adduct di (meth) acrylate and bisphenol A propylene oxide adduct di (meth) acrylate. The aromatic vinyls may be used alone or in combination of two or more. Of these, styrene is preferred from the viewpoint of availability.
(B) (Meth) acrylic acid ester The (meth) acrylic acid ester is not particularly limited, and examples thereof include (meth) acrylic acid alkyl esters. The carbon number of the alkyl group in the alkyl (meth) acrylate can be 1 to 5. Specific examples of (meth) acrylate include methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, and butyl (meth) acrylate. The (meth) acrylates may be used alone or in combination of two or more. From the viewpoint of improving the mechanical properties of the foam molded article, methyl (meth) acrylate is preferred, and methyl methacrylate is more preferred.
(C) Unsaturated dicarboxylic acid The unsaturated dicarboxylic acid is not particularly limited, and examples thereof include aliphatic unsaturated dicarboxylic acids having 2 to 6 carbon atoms. Specific examples of unsaturated dicarboxylic acids include maleic acid, itaconic acid, citraconic acid, aconitic acid, and anhydrides thereof. The unsaturated dicarboxylic acids may be used alone or in combination of two or more.

(D) Percentage of units derived from aromatic vinyl, (meth) acrylate and unsaturated dicarboxylic acid The sum of units derived from aromatic vinyl, (meth) acrylate and unsaturated dicarboxylic acid is 100 Assuming that the unit is parts by weight, a unit derived from aromatic vinyl is 30 to 80 parts by weight, a unit derived from (meth) acrylate is 8 to 35 parts by weight, and a unit derived from unsaturated dicarboxylic acid is 10 to 50 parts by weight. It is preferable to include
When the proportion of the unit derived from aromatic vinyl is less than 30 parts by weight, the foaming property of the foamed particles is reduced at the time of foam molding, and the heat-sealing integration of the foamed particles becomes insufficient and the foamed molded article Mechanical properties may be reduced. When this proportion is more than 80 parts by weight, the heat resistance of the foamed molded article may be reduced. This ratio is more preferably from 40 to 75 parts by weight, and even more preferably from 45 to 70 parts by weight.
If the proportion of the unit derived from the (meth) acrylate is less than 8 parts by weight, the mechanical properties of the foamed molded article may be reduced. If this proportion is greater than 35 parts by weight, the foaming properties of the foamed particles during foam molding may be reduced, and the heat fusion and integration of the foamed particles may be insufficient, and the mechanical properties of the foamed molded article may be reduced. is there. This ratio is more preferably from 10 to 33 parts by weight, and even more preferably from 15 to 30 parts by weight.
When the proportion occupied by the unit derived from the unsaturated dicarboxylic acid is less than 10 parts by weight, the heat resistance of the foamed molded article may be reduced. If this proportion is greater than 50 parts by weight, the foaming properties of the foamed particles may be reduced during foam molding, and the thermal fusion and integration of the foamed particles may be insufficient, and the mechanical properties of the foamed molded article may be reduced. is there. This ratio is more preferably from 15 to 40 parts by weight, and even more preferably from 20 to 35 parts by weight.
The amount of the monomer used and the content of the unit derived from the monomer substantially coincide with each other.
The ratio of each component, that is, the ratio of units derived from aromatic vinyl, (meth) acrylate and unsaturated dicarboxylic acid, and the ratio of units derived from other monomers and other resins described below is ¹ It can be defined by the peak height of H-NMR or the area ratio of FT-IR. A specific measuring method will be described in Examples.

(E) Other monomers The base resin may be a further copolymer with components derived from other monomers other than the above three monomers as long as the properties of the present invention are not impaired. Examples of other monomers include (meth) acrylonitrile, dimethyl maleate, diethyl maleate, dimethyl fumarate, diethyl fumarate, ethyl fumarate, (meth) acrylic acid and the like.
The proportion of units derived from other monomers in the base resin is preferably 30% by weight or less, and may be 0% by weight.
(F) Other Resins Other resins may be mixed with the base resin. As another resin, a rubber-modified resin containing a diene rubber-like polymer such as polyolefin resin such as polyethylene and polypropylene, polybutadiene, styrene-butadiene copolymer, and ethylene-propylene-non-conjugated diene three-dimensional copolymer is added. Styrene- (meth) acrylic acid copolymer such as impact polystyrene resin, polycarbonate resin, polyester resin, polyamide resin, polyphenylene ether, acrylonitrile-butadiene-styrene copolymer, acrylonitrile-styrene copolymer, polymethyl methacrylate, etc. Styrene- (meth) acrylate copolymer, aromatic vinyl-unsaturated dicarboxylic acid-unsaturated dicarboxylic acid imide copolymer, and the like.
Among the other resins, the expanded particles preferably contain polymethyl methacrylate. By containing polymethyl methacrylate, the heat-fusibility of the foamed particles is improved, and the foamed particles are more firmly heat-sealed together to form a foamed molded article having more excellent mechanical properties. Obtainable. The content of polymethyl methacrylate in the expanded particles is preferably from 10 to 500 parts by weight, more preferably from 20 to 450 parts by weight, and particularly preferably from 30 to 400 parts by weight based on 100 parts by weight of the copolymer.

It is preferable that the foamed particles contain an acrylic resin as a processing aid. By containing a processing aid, the melt tension (viscoelasticity) at the time of foaming of the resin constituting the foamed particles is set to be suitable for foaming, thereby suppressing the expansion of the foamed particles into open cells and expanding the foamed particles. By improving the properties, the heat fusion between the expanded particles can be further strengthened, and a foam molded article having more excellent mechanical properties can be manufactured. The content of the processing aid in the expanded particles is preferably 0.5 to 5 parts by weight, more preferably 0.5 to 3 parts by weight, based on 100 parts by weight of the copolymer.
The acrylic resin as a processing aid is not particularly limited, and may be a homopolymer of an acrylic monomer or a copolymer of two or more of these, containing 50% by weight or more of an acrylic monomer, and A copolymer of an acrylic monomer and a vinyl monomer copolymerizable with the acrylic monomer may be used. Examples of the acrylic monomer include methyl acrylate, ethyl acrylate, butyl acrylate, methyl methacrylate, ethyl methacrylate, butyl methacrylate, and the like. Examples of the vinyl monomer copolymerizable with the acrylic monomer include α-methylstyrene and acrylonitrile. The weight average molecular weight of the acrylic resin is preferably 1.5 to 6 million, more preferably 2 to 4.5 million, and particularly preferably 2.5 to 4 million. Even if the weight-average molecular weight of the acrylic resin is too low or too high, it is difficult to sufficiently adjust the melt tension (viscoelasticity) of the resin constituting the expanded particles during expansion molding to one suitable for expansion. In some cases, the foamability of the particles cannot be improved.

(G) Aromatic vinyl-unsaturated dicarboxylic acid-unsaturated dicarboxylic acid imide copolymer As the other resin (f), an aromatic vinyl-unsaturated dicarboxylic acid-unsaturated dicarboxylic acid imide copolymer includes: It is preferable from the viewpoint of improving the heat resistance of the foam molded article.
Examples of the aromatic vinyl include, but are not particularly limited to, the compounds exemplified in (a) above. The aromatic vinyls may be used alone or in combination of two or more. Of these, styrene is preferred from the viewpoint of availability.
The unsaturated dicarboxylic acid is not particularly limited, and examples thereof include the compounds exemplified in the above (c). The unsaturated dicarboxylic acids may be used alone or in combination of two or more. From the viewpoint of improving the mechanical properties of the foam molded article, maleic anhydride is preferred.
Examples of the unsaturated dicarboxylic acid imide include, but are not particularly limited to, maleimide monomers such as maleimide, N-methylmaleimide, N-ethylmaleimide, N-cyclohexylmaleimide, N-phenylmaleimide, and N-naphthylmaleimide. . The unsaturated dicarboxylic imide derivatives may be used alone or in combination of two or more. From the viewpoint of improving the heat resistance of the foam molded article, N-phenylmaleimide is preferred.
The proportion of units derived from aromatic vinyl, unsaturated dicarboxylic acid, and unsaturated dicarboxylic acid imide is 20 to 80 parts by weight, assuming that the total of the units derived from the three is 100 parts by weight. And 2 to 30 parts by weight of units derived from unsaturated dicarboxylic acid, and 20 to 80 parts by weight of units derived from unsaturated dicarboxylic acid imide.
When the proportion occupied by the units derived from aromatic vinyl is less than 20 parts by weight, the foaming property of the foamed particles is reduced at the time of foam molding, and the heat-sealing integration of the foamed particles becomes insufficient and the foamed molded article Mechanical properties may be reduced. When this proportion is more than 80 parts by weight, the heat resistance of the foamed molded article may be reduced. This ratio is more preferably from 30 to 75 parts by weight, even more preferably from 50 to 70 parts by weight.
(H) Additives The base resin may contain additives in addition to the resin, if necessary. Additives include plasticizers, flame retardants, flame retardant aids, antistatic agents, spreading agents, foam regulators, fillers, colorants, weathering agents, anti-aging agents, lubricants, anti-fog agents, fragrances, etc. No.

(1-2) Configuration In the cross-sectional photograph of the entire expanded bead obtained by photographing an area of 11.9 mm ^{2 at} a magnification of 30 times, the expanded bead has a small bubble having a bubble diameter of 50 μm or more and less than 300 μm and a bubble having a bubble diameter of 300 μm or more and 2 mm or less. With large bubbles.
In addition, the number of large cells per one foamed particle is not particularly limited, and may be plural. However, if the number is too large, the cell ratio increases, and the mechanical properties of the foamed molded article are reduced. For this reason, it is preferable that the foamed particles have only one large cell in one of them, though it depends on the cell diameter of the large cell.
Further, there is a difference between the average bubble diameter of the small bubbles and the average bubble diameter of the large bubbles of 1000 μm or more and less than 1500 μm. Due to this difference, it is possible to provide foamed particles that give a foamed molded article with improved mechanical properties. Here, the average bubble diameter of the small bubbles is preferably in the range of 30 to 100 μm, and the average bubble diameter of the large bubbles is preferably in the range of 1200 to 1600 μm.
Since the foamed particles give a maximum point stress in a bending test of 1.0 MPa or more to the foamed molded article formed from the fused body, the foamed molded article can provide a foamed molded article having high bending resistance. This range of the maximum point stress can be realized by foamed particles using a specific resin as a base resin and having cells in a specific cell diameter range. The maximum point stress is preferably at least 1.0 MPa, more preferably at least 1.5 MPa.

The outer shape of the foamed particles is not particularly limited as long as a foamed molded article can be produced, and examples thereof include a sphere, a substantially sphere, and a cylinder. The expanded particles preferably have an outer shape represented by an average aspect ratio of 0.7 or more (the upper limit is a true sphere of 1).
The expanded particles preferably have a volume multiple of 30 to 2 times. When the bulk factor is larger than 30 times, the open cell ratio of the foamed particles may increase, and the foamability of the foamed particles may decrease during foaming in foam molding. If it is less than twice, the cells of the foamed particles may be non-uniform, and the foamability of the foamed particles during foam molding may be insufficient. The bulk multiple is more preferably 25 to 3 times, and particularly preferably 20 to 5 times.

(1-3) Production Method As a method for producing expanded particles, a method in which resin particles are impregnated with a blowing agent in a gas phase to obtain expandable particles, and the expandable particles are expanded.
The resin particles can be obtained using a known production method and production equipment. Here, the number of voids described below can be adjusted, for example, by adjusting the amount of a chemical foaming agent or the like added to the resin.
For example, resin particles can be produced by melt-kneading the raw material resin using an extruder and then granulating by extrusion, underwater cut (underwater cut), strand cut, or the like. The temperature, time, pressure, etc., during melt-kneading can be appropriately set according to the raw materials used and the production equipment.
The melt-kneading temperature in the extruder at the time of melt-kneading is a temperature at which the raw material resin is sufficiently softened, preferably from 220 to 280 ° C, more preferably from 240 to 270 ° C. The melt-kneading temperature means the temperature of the melt-kneaded material inside the extruder obtained by measuring the temperature at the center of the flow path of the melt-kneaded material near the extruder head with a thermocouple thermometer.
Large bubbles, which are one of the characteristics of the expanded particles of the present invention, are considered to be derived from voids formed in the central region of the resin particles by rapid cooling from the surroundings during the production of the resin particles. Therefore, in the production of foamed particles, underwater cutting in which rapid cooling control is easy is particularly preferable.
It is preferable that the extruder be supplied with a bubble regulator. Examples of the cell regulator include polytetrafluoroethylene powder, polytetrafluoroethylene powder modified with an acrylic resin, and talc. The amount of the cell regulator is preferably 0.01 to 5 parts by weight based on 100 parts by weight of the resin composition. When the amount of the cell regulator is less than 0.01% by weight, the cells of the expanded particles become coarse, and the appearance of the obtained foamed molded article may be deteriorated. If the amount is more than 5 parts by weight, the closed cells ratio of the foamed particles may be reduced due to foam breaking. The amount of the cell regulator is more preferably 0.05 to 3 parts by weight, and particularly preferably 0.1 to 2 parts by weight.

Next, as a method for producing the expandable particles, there is a method in which the resin particles are gas-phase impregnated with a blowing agent in a sealable container. Examples of the blowing agent include propane, normal butane, isobutane, normal pentane, isopentane, saturated aliphatic hydrocarbons such as hexane, ethers such as dimethyl ether, methyl chloride, 1,1,1,2-tetrafluoroethane, Inorganic gases such as 1-difluoroethane and monochlorodifluoromethane such as chlorofluorocarbons, carbon dioxide, and nitrogen are exemplified. Among them, dimethyl ether, propane, normal butane, isobutane and carbon dioxide are preferred, propane, normal butane, isobutane and carbon dioxide are more preferred, and normal butane, isobutane and carbon dioxide are particularly preferred. The blowing agents may be used alone or in combination of two or more.
If the amount of the foaming agent charged into the container is too small, the foamed particles may not be able to be foamed to a desired foaming ratio. If the amount of the foaming agent is too large, the foaming agent acts as a plasticizer, so that the viscoelasticity of the base resin is too low, so that the foaming property is reduced and good foamed particles may not be obtained. Therefore, the amount of the foaming agent is preferably 0.1 to 5 parts by weight, more preferably 0.2 to 4 parts by weight, and particularly preferably 0.3 to 3 parts by weight based on 100 parts by weight of the raw material resin.
Further, as a method for producing the foamed particles, there is a method in which the foamed particles are heated with a heating medium such as steam in a sealable container. Examples of the heating conditions include a gauge pressure of 0.3 to 0.5 MPa, a temperature of 120 to 159 ° C., and 10 to 180 seconds.
The particle size of the foamed particles can be varied by changing the diameter of a multi-nozzle mold attached to the front end of the extruder.

(2) Foam molded article (2-1) Base resin The base resin constituting the foam molded article is the same as the base resin of the foamed particles.
(2-2) Physical properties The foam molded article is composed of a plurality of foam particles. Each of the foamed particles has small bubbles having a bubble diameter of 50 μm or more and less than 300 μm and large bubbles having a bubble diameter of 300 μm or more and 2 mm or less in a cross-sectional photograph of an area of 11.9 mm ^{2 at} a magnification of 30 times. .
In addition, the number of large cells per one foamed particle is not particularly limited, and may be plural. However, if the number is too large, the cell ratio increases, and the mechanical properties of the foamed molded article are reduced. For this reason, it is preferable that the foamed particles have only one large cell in one of them, though it depends on the cell diameter of the large cell.
Further, there is a difference between the average bubble diameter of the small bubbles and the average bubble diameter of the large bubbles of 1000 μm or more and less than 1500 μm. Due to this difference, it is possible to provide a foamed particle that gives a foamed molded article that is resistant to bending. Here, the average bubble diameter of the small bubbles is preferably in the range of 30 to 100 μm, and the average bubble diameter of the large bubbles is preferably in the range of 1200 to 1800 μm.
Since the foamed particles give a maximum point stress in a bending test of 1.0 MPa or more to the foamed molded article formed from the fused body, the foamed molded article can provide a foamed molded article having high bending resistance. This range of the maximum point stress can be realized by foamed particles using a specific resin as a base resin and having cells in a specific cell diameter range. The maximum point stress is preferably at least 1.0 MPa, more preferably at least 1.5 MPa.

The outer shape of the fused foamed particles is not particularly limited as long as the foamed molded body can be maintained.
The foamed molded article preferably has a multiple of 30 to 2 times. When the multiple is more than 30 times, mechanical properties may be insufficient. If it is less than twice, the advantage of foaming may be reduced due to the increased weight. The multiple is preferably 25 to 3 times, more preferably 20 to 5 times.
Therefore, it is preferable that the foam molded article has a density of 0.058 to 0.23 g / cm ³ (58 to 230 kg / cm ³ ).

The maximum bending point stress per unit density in the foamed molded body is preferably 0.015 MPa / (kg / m ³ ) or more. If the bending maximum point stress is too small, the foam molded article may be easily broken.
The flexural modulus per unit density of the foamed molded product is preferably 0.4 MPa / (kg / m ³ ) or more. If the flexural modulus is too small, the foam molded article may be deformed by the pressure applied when laminating and integrating a skin material such as fiber reinforced plastic on the surface of the foam molded article.
5% compressive stress per unit density in the foam molded article is preferably from 0.008MPa / (kg / m ³⁾ or ^{more, 0.009MPa / (kg / m 3} ) or more is more preferable. If the 5% compression is too small, the foam molded article may be deformed by the pressure applied when laminating and integrating a skin material such as fiber reinforced plastic on the surface of the foam molded article.
The compression elastic modulus per unit density of the foamed molded product is preferably 0.3 MPa / (kg / m ³ ) or more. If the compression modulus is too small, the foam molded article may be deformed by the pressure applied when laminating and integrating a skin material such as fiber reinforced plastic on the surface of the foam molded article.

(2-3) Manufacturing Method As a method for manufacturing a foamed molded article, foamed particles are filled in a cavity of a mold, a heating medium is supplied into the cavity, and the foamed particles are heated and refoamed, and then refoamed. A method of obtaining a foamed molded article by thermally fusing the foamed particles with each other by these foaming pressures. Examples of the heating medium include steam, hot air, hot water, and the like, and steam is preferred.

(2-4) Use The foamed molded article is excellent in lightness, heat resistance, and mechanical properties, and is particularly excellent in load resistance in a high-temperature environment. Therefore, for example, it can be suitably used for parts of transportation equipment such as automobiles, aircraft, railway vehicles, and ships. Examples of automobile parts include parts used near the engine, exterior materials, and the like.
According to the present invention, there is provided an automotive component comprising the foamed molded article of the present invention. Examples of the automotive component include a floor panel, a roof, a hood, a fender, an undercover, a wheel, a steering wheel, and a container. (Housing), hood panel, suspension arm, bumper, sun visor, trunk lid, luggage box, seat, door, cowl, and the like.

A skin material may be laminated and integrated on the surface of the foam molded article to be used as a reinforced composite. When the foamed molded article is a foamed sheet, it is not necessary to be laminated and integrated on both sides of the foamed molded article, and it is sufficient that the skin material is laminated and integrated on at least one of the two surfaces of the foamed molded article. The lamination of the skin material may be determined according to the use of the reinforced composite. Above all, in consideration of the surface hardness and mechanical strength of the reinforced composite, it is preferable that the skin material is laminated and integrated on both surfaces in the thickness direction of the foamed molded product.
The skin material is not particularly limited, and examples thereof include a fiber reinforced plastic, a metal sheet, and a synthetic resin film. Of these, fiber reinforced plastics are preferred. A reinforced composite using fiber reinforced plastic as a skin material is referred to as a fiber reinforced composite.
The reinforcing fibers constituting the fiber-reinforced plastic include inorganic fibers such as glass fiber, carbon fiber, silicon carbide fiber, alumina fiber, Tyranno fiber, basalt fiber, and ceramic fiber; metal fibers such as stainless steel fiber and steel fiber; and aramid. Organic fibers such as fibers, polyethylene fibers, and polyparaphenylenebenzoxadol (PBO) fibers; and boron fibers. The reinforcing fibers may be used alone or in combination of two or more. Among them, carbon fibers, glass fibers and aramid fibers are preferred, and carbon fibers are more preferred. These reinforcing fibers have excellent mechanical properties despite their light weight.

The reinforcing fiber is preferably used as a reinforcing fiber base processed into a desired shape. Examples of the reinforcing fiber base include a woven fabric, a knitted fabric, and a nonwoven fabric using the reinforcing fiber, and a face material formed by binding (sewing) a fiber bundle (strand) in which reinforcing fibers are aligned in one direction with a thread. . Examples of the weaving method of the woven fabric include plain weave, twill weave, and satin weave. Examples of the yarn include a synthetic resin yarn such as a polyamide resin yarn and a polyester resin yarn, and a stitch yarn such as a glass fiber yarn.
The reinforcing fiber base may be used without laminating only one reinforcing fiber base, or may be used as a laminated reinforcing fiber base by laminating a plurality of reinforcing fiber bases. As the laminated reinforcing fiber base material obtained by laminating a plurality of reinforcing fiber base materials, (1) a plurality of one kind of reinforcing fiber base material is prepared, and a laminated reinforcing fiber base material obtained by laminating these reinforcing fiber base materials; 2) A plurality of types of reinforcing fiber base materials are prepared, a laminated reinforcing fiber base material obtained by stacking these reinforcing fiber base materials, and (3) a fiber bundle (strand) in which reinforcing fibers are aligned in one direction are bound with yarn ( A plurality of reinforced fiber substrates are prepared, and the reinforced fiber substrates are overlapped so that the fiber directions of the fiber bundles are directed in different directions. For example, a laminated reinforced fiber base material integrated (sewed) with the above is used.

The fiber-reinforced plastic is obtained by impregnating a reinforcing fiber with a synthetic resin. The reinforcing fibers are bound and integrated by the impregnated synthetic resin.
The method for impregnating the reinforcing fiber with the synthetic resin is not particularly limited, and examples thereof include (1) a method of immersing the reinforcing fiber in the synthetic resin, and (2) a method of applying the synthetic resin to the reinforcing fiber.
As the synthetic resin to be impregnated into the reinforcing fibers, either a thermoplastic resin or a thermosetting resin can be used, and a thermosetting resin is preferably used. The thermosetting resin to be impregnated into the reinforcing fibers is not particularly limited, and may be epoxy resin, unsaturated polyester resin, phenol resin, melamine resin, polyurethane resin, silicone resin, maleimide resin, vinyl ester resin, cyanate ester resin, maleimide. Epoxy resins and vinyl ester resins are preferred because they include a resin obtained by prepolymerizing a resin and a cyanate ester resin, and are excellent in heat resistance, shock absorption or chemical resistance. The thermosetting resin may contain additives such as a curing agent and a curing accelerator. The thermosetting resin may be used alone, or two or more kinds may be used in combination.

The thermoplastic resin to be impregnated into the reinforcing fibers is not particularly limited, and examples thereof include an olefin resin, a polyester resin, a thermoplastic epoxy resin, an amide resin, a thermoplastic polyurethane resin, a sulfide resin, and an acrylic resin. In addition, polyester resins and thermoplastic epoxy resins are preferred because they are excellent in adhesiveness to a foamed molded article or adhesiveness between reinforcing fibers constituting a fiber-reinforced plastic. The thermoplastic resin may be used alone, or two or more kinds may be used in combination.
The thermoplastic epoxy resin is a polymer or copolymer of epoxy compounds having a linear structure, or a copolymer of an epoxy compound and a monomer polymerizable with the epoxy compound. And a copolymer having a linear structure. Specifically, as the thermoplastic epoxy resin, for example, bisphenol A type epoxy resin, bisphenol fluorene type epoxy resin, cresol novolak type epoxy resin, phenol novolak type epoxy resin, cycloaliphatic type epoxy resin, long chain aliphatic type Epoxy resins, glycidyl ester type epoxy resins, glycidylamine type epoxy resins and the like are mentioned, and bisphenol A type epoxy resins and bisphenol fluorene type epoxy resins are preferred. The thermoplastic epoxy resin may be used alone, or two or more kinds may be used in combination.

Examples of the thermoplastic polyurethane resin include a polymer having a linear structure obtained by polymerizing a diol and a diisocyanate. Examples of the diol include ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol, 1,3-butanediol, 1,4-butanediol, and the like. The diols may be used alone or in combination of two or more. Examples of the diisocyanate include an aromatic diisocyanate, an aliphatic diisocyanate and an alicyclic diisocyanate. The diisocyanates may be used alone or in combination of two or more. The thermoplastic polyurethane resin may be used alone, or two or more kinds may be used in combination.
The content of the synthetic resin in the fiber reinforced plastic is preferably from 20 to 70% by weight. When the content is less than 20% by weight, the binding properties between the reinforcing fibers and the adhesiveness between the fiber-reinforced plastic and the foamed molded article become insufficient, and the mechanical properties of the fiber-reinforced plastic and the mechanical strength of the fiber-reinforced composite are reduced. May not be sufficiently improved. If the content is more than 70% by weight, the mechanical properties of the fiber-reinforced plastic may decrease, and the mechanical strength of the fiber-reinforced composite may not be sufficiently improved. The content is more preferably 30 to 60% by weight.
The thickness of the fiber reinforced plastic is preferably 0.02 to 2 mm, more preferably 0.05 to 1 mm. A fiber reinforced plastic having a thickness within this range is excellent in mechanical properties despite its light weight.
Basis weight of the fiber reinforced plastic is preferably ^{50~4000g / m 2, 100~1000g / m} 2 is more preferable. Fiber reinforced plastics having a basis weight within this range are excellent in mechanical properties despite being lightweight.

Next, a method for producing a reinforced composite will be described. The method for producing a reinforced composite body by laminating and integrating a skin material on the surface of a foamed molded article is not particularly limited. For example, (1) laminating and unifying a skin material on the surface of a foamed molded article via an adhesive. (2) Laminating a fiber-reinforced plastic forming material obtained by impregnating a reinforcing fiber with a thermoplastic resin on the surface of a foamed molded article, and using the thermoplastic resin impregnated in the reinforcing fiber as a binder to form a foamed molded article Method of laminating and integrating a fiber-reinforced plastic forming material as a fiber-reinforced plastic on the surface of (3) Laminating a fiber-reinforced plastic forming material in which uncured thermosetting resin is impregnated into reinforcing fibers on the surface of a foamed molded article And a method of laminating and integrating a fiber-reinforced plastic formed by curing the thermosetting resin with the thermosetting resin impregnated in the reinforcing fibers as a binder, on the surface of the foamed molded article; A heated and softened skin material is disposed on the surface of the foam molded body, and the skin material is deformed along the surface of the foam molded body as necessary by pressing the skin material against the surface of the foam molded body. A method of laminating and integrating it on the surface of the foamed molded article, and (5) a method generally applied in molding of fiber reinforced plastic. From the viewpoint that the foamed molded article has excellent mechanical properties such as load resistance under a high temperature environment, the method (4) can also be suitably used.
Examples of the method used for molding the fiber reinforced plastic include an autoclave method, a hand lay-up method, a spray-up method, a PCM (Prepreg Compression Molding) method, an RTM (Resin Transfer Molding) method, and a VaRTM (Vacuum assisted Resin Transfer) method. And the like.

The fiber-reinforced composite thus obtained is excellent in heat resistance, mechanical strength, and lightness. Therefore, it can be used in a wide range of applications such as in the field of transportation equipment such as automobiles, aircraft, railway vehicles, and ships, in the field of home appliances, in the field of information terminals, and in the field of furniture.
For example, fiber-reinforced composites include transport equipment components, transport equipment component parts (especially automotive parts) including structural components constituting the main body of the transport equipment, windmill wings, robot arms, cushioning materials for helmets, It can be suitably used as a transportation container such as an agricultural box, a heat insulation / cooling container, a rotor blade of an industrial helicopter, and a component packing material.
According to the present invention, there is provided an automotive component comprising the fiber-reinforced composite of the present invention. As the automotive component, for example, a floor panel, a roof, a bonnet, a fender, an undercover, a wheel, a steering wheel, Components include a container (housing), a hood panel, a suspension arm, a bumper, a sun visor, a trunk lid, a luggage box, a seat, a door, and a cowl.

  Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited thereto. First, measurement methods and evaluation methods in Examples and Comparative Examples will be described.

(Glass-transition temperature)
The glass transition temperature was measured by a method described in JIS K7121: 1987 "Method for measuring plastic transition temperature". However, sampling methods and temperature conditions were as follows.
Approximately 6 mg of a sample was filled in the bottom of an aluminum measurement container using a differential scanning calorimeter device DSC6220 type (manufactured by SII NanoTechnology Inc.) so that there was no gap. The sample was heated from 30 ° C. to 220 ° C. at a rate of 20 ° C./min under a nitrogen gas flow rate of 20 mL / min. After holding for 10 minutes, the sample was taken out immediately, allowed to cool in an environment of 25 ± 10 ° C., and obtained from a DSC curve obtained when the temperature was raised from 30 ° C. to 220 ° C. at a rate of 20 ° C./min. The glass transition temperature (starting point) was calculated. At this time, alumina is used as a reference material. The glass transition onset temperature was determined from a standard (9.3 "How to determine glass transition temperature").

(Bulk density and bulk multiple)
The bulk density was measured according to JIS K6911: 1995 “General thermosetting plastic test method”. That is, the bulk density was measured using an apparent density measuring device based on JIS K6911, and the bulk density was measured based on the following equation.
Bulk density of expanded particles (kg / m ³ ) = [weight of measuring cylinder containing sample (kg) −weight of measuring cylinder (kg)] / [volume of measuring cylinder (m ³ )]
The bulk multiple was a value obtained by integrating the density of the resin with the reciprocal of the bulk density.

(Bending test: density, maximum point load, stress, displacement and energy)
The load, stress, displacement and energy at the maximum point were measured by a method in accordance with JIS K7221-1: 2006 "Hard foamed plastic-Bending test-Part 1: Determination of deflection characteristics". That is, a rectangular parallelepiped test piece having a length of 20 mm, a width of 25 mm, and a height of 130 mm was cut out from the foam molded article. For the measurement, a Tensilon universal tester (“UCT-10T” manufactured by Orientec) was used. The bending maximum point stress of the bending strength was calculated using a universal testing machine data processing system ("UTPS-237S Ver, 1.00" manufactured by Soft Brain).
The strip-shaped test piece was placed on a support, and the maximum bending stress was measured under the conditions of a load cell of 1000 N, a test speed of 10 mm / min, a jig 5R at the tip of the support, and an opening width of 100 mm. The number of test pieces is 5 or more, and the condition is the same after conditioned in a standard atmosphere of second grade for 16 hours under the symbol “23/50” (temperature 23 ° C., relative humidity 50%) of JIS K 7100: 1999. It was measured under a standard atmosphere. The arithmetic mean value of the maximum bending point stress of each test piece was defined as the maximum bending point stress of the foam molded article.
The maximum bending point stress per unit density was calculated by dividing the maximum bending point stress by the density of the foam molded article.
In addition, the density (kg / m ³ ) of the foamed molded body was determined by the formula (a) / (b) by measuring the weight (a) and the volume (b) of a test piece cut from the foamed molded body.

(Bending test: elastic modulus)
The flexural modulus was measured by a method in accordance with JIS K7221-1: 2006 "Hard foamed plastic-Bending test-Part 1: Determination of deflection characteristics". That is, a rectangular parallelepiped test piece having a length of 20 mm, a width of 25 mm, and a height of 130 mm was cut out from the foam molded article. For the measurement, a Tensilon universal tester (“UCT-10T” manufactured by Orientec) was used. The flexural modulus was calculated using a universal testing machine data processing system ("UTPS-237S Ver, 1.00" manufactured by Soft Brain). The number of test pieces is 5 or more, and the condition is the same after conditioned in a standard atmosphere of second grade for 16 hours under the symbol “23/50” (temperature 23 ° C., relative humidity 50%) of JIS K 7100: 1999. It was measured under a standard atmosphere. The arithmetic mean value of the compressive modulus of each test piece was defined as the flexural modulus of the foam molded article.
The flexural modulus was calculated by the following equation using the straight line at the beginning of the load-deformation curve.
E = Δσ / Δε
E: Flexural modulus (MPa)
Δσ: difference in stress between two points on a straight line (MPa)
Δε: difference in deformation between the same two points (%)
The flexural modulus per unit density was calculated by dividing the flexural modulus by the density of the foam molded article.

(Compression test: density and 5%, 10% and 25% stress)
The 5% compressive stress, 10% compressive stress, and 25% compressive stress of the foamed molded article were measured by the method described in JIS K7220: 2006 “Hard foamed plastics—How to determine compression properties”. That is, using a Tensilon universal testing machine (“UCT-10T” manufactured by Orientec) and a universal testing machine data processing system (“UTPS-237S Ver, 1.00” manufactured by Soft Brain), the specimen size cross section was 50 mm. The compression strength (5% deformation compression stress, 25% deformation compression stress, compression modulus) was measured at a compression rate of 2.5 mm / min with a size of × 50 mm and a thickness of 25 mm. The number of test pieces is 5 or more, and the condition is the same after conditioned in a standard atmosphere of second grade for 16 hours under the symbol “23/50” (temperature 23 ° C., relative humidity 50%) of JIS K 7100: 1999. The measurement was performed under a standard atmosphere. The arithmetic mean values of the compressive strengths (5% deformation compressive stress, 10% deformation compressive stress, 25% deformation compressive stress) of each test piece were respectively calculated as 5% compressive stress, 10% compressive stress, 25% Compressive stress was used.
(5% (10%, 25%) deformation compressive stress)
The 5% (10%, 25%) deformation compressive stress was calculated by the following equation. The conditions in parentheses are conditions for calculating 10% deformation compressive stress and 25% deformation compressive stress.
σ5 (10, 25) = F5 (10, 25) / A ₀
σ5 (10, 25): 5% (10%, 25%) deformation compressive stress (MPa)
F5 (10, 25): Force (N) at 5% (10%, 25%) deformation
A ₀ : initial cross-sectional area of test piece (mm ² )
The 5% deformation compressive stress per unit density was calculated by dividing the 5% deformation compressive stress by the density of the foam molded article.

(Compression test: elastic modulus)
The compression elastic modulus of the foamed molded article was measured by the method described in JIS K7220: 2006 “Hard foamed plastic-Determination of compression characteristics”. That is, using a Tensilon universal testing machine (“UCT-10T” manufactured by Orientec) and a universal testing machine data processing system (“UTPS-237S Ver, 1.00” manufactured by Soft Brain), the specimen size cross section was 50 mm. The compression modulus was measured at a compression rate of 2.5 mm / min with a size of × 50 mm and a thickness of 25 mm. The number of test pieces is 5 or more, and the condition is the same after conditioned in a standard atmosphere of second grade for 16 hours under the symbol “23/50” (temperature 23 ° C., relative humidity 50%) of JIS K 7100: 1999. The measurement was performed under a standard atmosphere. The arithmetic mean value of the compressive modulus of each test piece was defined as the compressive modulus of the foam molded article.
(Compressive modulus)
The compression modulus was calculated by the following equation using the straight line at the beginning of the load-deformation curve.
E = Δσ / Δε
E: compression modulus (MPa)
Δσ: difference in stress between two points on a straight line (MPa)
Δε: difference in deformation between the same two points (%)
Further, the compression elastic modulus per unit density was calculated by dividing the compression elastic modulus by the density of the foam molded article.

(Ratio of resin component of base resin)
( ¹ H-NMR)
The measurement was performed under the following conditions using an ECX400P nuclear magnetic resonance apparatus manufactured by JEOL Ltd.
<Measurement conditions>
・ Measurement mode Single pulse ・ Pulse width 45 ° (6.05μsec)
・ Points 32k
・ Repeat time 7.0 seconds ・ Integration count 128 times ・ Measurement solvent deuterated chloroform ・ Sample concentration about 20mg / 0.6mL
・ Measurement temperature 50 ℃
・ Chemical shift standard chloroform: 7.24ppm
・ Measurement range 20 ppm (-5 ppm to 15 ppm)
・ Window function exponnential (BF: 0.12 Hz)
The composition ratio of the base resin was calculated from the integrated intensity ratio of each signal of the spectrum obtained from the ¹ H-NMR measurement. When a signal presumed to be derived from impurities is observed in each signal region, these contributions were ignored in the calculation.

(FT-IR)
The absorbance ratio (D1780 / D698, D1720 / D698) of the base resin was measured in the following manner.
Surface analysis was performed on each of the 10 randomly selected resin particles by an infrared spectroscopic analysis ATR measurement method to obtain an infrared absorption spectrum. In this analysis, an infrared absorption spectrum in a depth range from the sample surface to several μm (about 2 μm) was obtained. The absorbance ratio (D1780 / D698, D1720 / D698) was calculated from each infrared absorption spectrum, and the arithmetic mean of the calculated absorbance ratio was defined as the absorbance ratio.
The absorbances D1780, D1720 and D698 are obtained by connecting "Smart-iTR" manufactured by Thermo SCIENTIFIC as an ATR accessory to a measuring device sold under the trade name "Fourier transform infrared spectrophotometer Nicolet iS10" from Thermo SCIENTIFIC. It was measured. Infrared spectroscopy ATR measurement was performed under the following conditions.

<Measurement conditions>
-Measuring device: Fourier transform infrared spectrophotometer Nicolet iS10 (manufactured by Thermo SCIENTIFIC) and single reflection horizontal ATR Smart-iTR (manufactured by Thermo SCIENTIFIC)
・ ATR crystal: Diamond with ZnSe lenses, angle = 42 °
・ Measurement method: single ATR method ・ Measurement wave number region: 4000 cm ^{-1 to} 650 cm ^-1
-Wave number dependence of measurement depth: uncorrected-Detector: deuterated triglycine sulfate (DTGS) detector and KBr beam splitter-Resolution: 4 cm ^-1
・ Number of integration: 16 times (same for background measurement)
In the ATR method, since the intensity of the infrared absorption spectrum obtained by the measurement changes depending on the degree of adhesion between the sample and the high refractive index crystal, the degree of adhesion is almost uniform by applying the maximum load applied by the "Smart-iTR" of the ATR accessory. Was measured.
The infrared absorption spectrum obtained under the above conditions was subjected to peak processing as follows to obtain D1780, D1720 and D698, respectively.
The absorbance D1780 at 1780 cm ⁻¹ obtained from the infrared absorption spectrum was defined as the absorbance corresponding to the absorption spectrum derived from the inverse symmetric stretching vibration of two carbonyl groups in maleic anhydride due to C ＝ O.
In the measurement of the absorbance, no peak separation was performed even when another absorption spectrum overlapped at 1780 cm ^-1 . Absorbance D1780 is a straight line connecting the 1920Cm ^-1 and 1620 cm ^-1 as a baseline, and the maximum absorbance between 1810 cm ^-1 and 1745 cm ^-1.

Further, the absorbance D1720 at 1720 cm ^-1 was an absorbance corresponding to an absorption spectrum derived from an antisymmetric stretching vibration due to a carbonyl group C 基 O contained in methyl methacrylate.
In the measurement of the absorbance, peak separation is not performed even when another absorption spectrum is overlapped at 1720 cm ^-1 . Absorbance D1720 is a straight line connecting the 1920Cm ^-1 and 1620 cm ^-1 as a baseline, and the maximum absorbance between 1745 cm ^-1 and 1690 cm ^-1.
The absorbance D698 at 698 cm ^-1 was an absorbance corresponding to an absorption spectrum derived from out-of-plane bending vibration of CH in a monosubstituted benzene ring in styrene.
In the measurement of the absorbance, peak separation was not performed even when another absorption spectrum overlapped at 698 cm ^-1 . Absorbance D698 is a straight line connecting the 1510 cm ^-1 and 810 cm ^-1 as a baseline, and the maximum absorbance between 720 cm ^-1 and 660 cm ^-1.

Styrene, methyl methacrylate, and maleic anhydride ratios (% by weight) were calculated from the absorbance ratios (D1780 / D698, D1720 / D698) based on the calibration curve described below. In addition, the peak processing method used the same method as the above-mentioned resin particle.
As a method of obtaining the composition ratio of styrene and methyl methacrylate from the absorbance ratio, a plurality of types of standard samples were prepared by uniformly mixing a styrene resin and a methyl methacrylate resin at a predetermined composition ratio.
Specifically, a monomer obtained by weighing methyl methacrylate and styrene at a weight ratio of 0/100, 20/80, 40/60, 50/50 and 60/40, respectively, was put into a 10 ml screw vial, Then, 10 parts by weight of 2,2'-azobis (2,4-dimethylvaleronitrile) was added to 100 parts by weight of the monomer to dissolve the monomer. The obtained mixed solution is transferred to a 2 ml sample tube (φ7 mm × 122 mm × 190 mm), and the tube is sealed after purging with nitrogen. Next, this was placed in a water bath set at 65 ° C. and heated for 10 hours to complete the polymerization, and the polymer taken out from the ampule was used as a standard sample.
After the infrared absorption spectrum of each standard sample was obtained by the infrared spectroscopy ATR method, the absorbance ratio (D1780 / D698) was calculated. Then, a calibration curve was drawn by taking the composition ratio (the styrene resin ratio in the standard sample =% by weight) on the vertical axis and the absorbance ratio (D1780 / D698) on the horizontal axis. Based on this calibration curve, the composition ratio of the styrene resin and the methyl methacrylate resin could be determined.

Further, as a standard sample of a styrene resin and a maleic anhydride resin, a 1/1 copolymer of styrene and maleic anhydride (trade name, manufactured by SMA1000 (P) CRAY VALLEY) and a 3/1 copolymer of styrene and maleic anhydride were used. A polymer (SMA3000 (P) CRAY VALLEY) was used.
After obtaining an infrared absorption spectrum of each standard sample by the infrared spectroscopic analysis ATR method, the absorbance ratio (D1720 / D698) was calculated. Then, a calibration curve was drawn by taking the composition ratio (the ratio of styrene resin in the standard sample =% by weight) on the vertical axis and the absorbance ratio (D1720 / D698) on the horizontal axis. Based on this calibration curve, the composition ratio of the styrene resin and the maleic anhydride resin could be determined.
The composition ratios of styrene and methyl methacrylate and styrene and maleic anhydride were determined from the calibration curve. From the respective composition ratios, the composition ratios of the three components of styrene, methyl methacrylate, and maleic anhydride in the resin were determined by the following procedure.
Here, the ratio of each standard sample was set as follows.
Methyl methacrylate: styrene = A: B [1]
Styrene: maleic anhydride = C: D [2]
Since styrene is a common term, the styrene ratio C of [2] was adjusted to the styrene ratio B of [1].
From [2] Styrene: maleic anhydride = C: D
= C × (B / C): D × (B / C)
= B: D × (B / C) [3]
According to [3], the ratio of styrene becomes equal to [1]. Therefore, the abundance ratios of methyl methacrylate, styrene, and maleic anhydride were as follows from [1] and [3].
Methyl methacrylate: styrene: maleic anhydride = A: B: D × (B / C) [4]
From the abundance ratio of [4], the ratio of each component was as follows.
Methyl methacrylate = {A / ((A + B + D × (B / C))} × 100
Styrene = {B / ((A + B + D × (B / C))} × 100
Maleic anhydride = {D × (B / C) / ((A + B + D × (B / C))} × 100

(Bubble number)
The number of bubbles in the foamed particles and foamed foam was measured in the following manner. First, an area of 11.9 mm ² was photographed at a magnification of 30 using a scanning electron microscope (“SU1510” manufactured by Hitachi High-Technologies Corporation). Regarding the expanded particles, the center of the cross section substantially divided into two at the center of the expanded particles was photographed. The photographed image was printed on A4 paper, and the average bubble diameter was calculated for all the bubbles. The bubble diameter was obtained by measuring the major axis and the minor axis of the cell cross section and calculating the arithmetic mean of the minor axis and the major axis. Specifically, on the outer contour line of the bubble cross section, any two points at which the mutual distance is the largest were selected, and the distance between these two points was defined as "the major axis of the bubble". In addition, any two points where the mutual distance is the largest are selected from any two points where a straight line orthogonal to the long diameter of the bubble and the outer contour line of the bubble cross section are selected, and the distance between the two points is set to “ "Short diameter of bubble". The number of individual bubbles was counted on paper for small bubbles having an average bubble diameter of 50 μm or more and less than 300 μm and for large bubbles having a bubble diameter of 300 μm or more and 2 mm or less.
In the same manner as described above, the nine foamed particles and the foamed molded body are cut, respectively, to obtain enlarged photographs. Based on these enlarged photographs, the number of individual bubbles of small bubbles and the individual bubbles of large bubbles are determined in the same manner as described above. The number was calculated. The arithmetic average of the number of 10 individual bubbles was defined as the number of bubbles.

(Average bubble diameter of large and small bubbles)
The average cell diameter of the large cells and the average cell diameter of the small cells were measured by the following methods.
The average cell diameter of the large cells is determined by scanning a scanning electron microscope (“SU1510”, manufactured by Hitachi High-Technologies Corporation) at the center of the cross section of the foamed particles, which is roughly divided into two at the center of the expanded particles, and at an arbitrary cut surface for the molded product. An image of 11.9 mm ² was photographed at a magnification of 30 times. The photographed image was printed on A4 paper, and the bubble diameter was calculated for all the large bubbles. The bubble diameter was obtained by measuring the major axis and the minor axis of the cell cross section and calculating the arithmetic mean of the minor axis and the major axis. Specifically, on the outer contour line of the bubble cross section, any two points at which the mutual distance is the largest were selected, and the distance between these two points was defined as "the major axis of the bubble". In addition, any two points where the mutual distance is the largest are selected from any two points where a straight line orthogonal to the long diameter of the bubble and the outer contour line of the bubble cross section are selected, and the distance between the two points is set to “ "Short diameter of bubble".
Nine expanded particles and the foamed molded article were cut in the same manner as described above, and enlarged photographs were obtained. Based on these enlarged photographs, the average cell diameter of large cells was calculated in the same manner as described above. The arithmetic mean value of the cell diameters of the large cells in the ten photographs was defined as the average cell diameter.
The average cell diameter of the small bubbles is determined by using a scanning electron microscope ("SU1510" manufactured by Hitachi High-Technologies Corporation) at the center of the cross section of the foamed particles at the center and at an arbitrary cut surface of the molded product. Taken.
At this time, the micrograph was taken so as to have a predetermined magnification when printed in a state where two images (a total of four images) were arranged side by side on one landscape A4 sheet. Specifically, when an arbitrary 60 mm straight line parallel to each of the vertical direction (the vertical direction of the image) and the horizontal direction (the horizontal direction of the image) is drawn on the image printed as described above, The magnification with an electron microscope was adjusted so that the number of bubbles existing on an arbitrary straight line was about 10 to 50. Micrographs of a total of two visual fields were taken for each cross-section of the two expanded particles, one for each visual field, and printed on A4 paper as described above.
Three arbitrary straight lines (length: 60 mm) parallel to the vertical and horizontal directions were drawn on each of the two images of the expanded particle cross section, and six arbitrary straight lines were drawn for each direction.
In addition, an arbitrary straight line did not contact large bubbles, and as much as possible, the bubbles were prevented from contacting only at the contact points. If they did, the bubbles were added to the number. The number of bubbles counted for six arbitrary straight lines in each of the vertical direction and the horizontal direction was arithmetically averaged to obtain the number of bubbles in each direction.
The average chord length (t) of the bubbles was calculated from the following formula from the magnification of the image in which the number of bubbles was counted and the number of bubbles.
Average chord length t (mm) = 60 / (number of bubbles x photo magnification)
The magnification of the image was obtained by measuring the scale bar on the photograph up to 1/100 mm using a “Digimatic caliper” manufactured by Mitutoyo Corporation, and calculating the following formula.
Image magnification = actual measured value of scale bar (mm) / display value of scale bar (mm)
And the bubble diameter in each direction was calculated by the following formula.
Bubble diameter D (mm) = t / 0.616
Further, the square root of the product was defined as the average cell diameter of the small cells.
Average bubble diameter of small bubbles (mm) = (D vertical x D horizontal) ^1/2

(Example 1)
(Resin particle manufacturing process)
Styrene-methyl methacrylate-maleic anhydride copolymer (trade name “DENKA RESISTY R-310”, manufactured by Denka Co., Ltd., styrene: 62 parts by weight, methyl methacrylate: 12 parts by weight, maleic anhydride: 26 parts by weight, density 1.15 g / cm ³ ) of 100 parts by weight was supplied at a rate of 10 kg / hr per hour to a single-screw extruder having a diameter of 40 mm and melt-kneaded at 270 ° C. Subsequently, cooling water of about 70 ° C. was supplied from a die hole (five nozzles having a diameter of 0.8 mm arranged) of a die (temperature: 285 ° C., resin pressure at the entrance side: 13 MPa) mounted on the tip of the single screw extruder. The resin particles are extruded into the housed chamber, and the rotary shaft of a rotary blade having six cutting blades is rotated at a rotation speed of 5000 rpm, cut into granules, cooled with the cooling water, and dehydrated and dried to obtain resin particles. Produced. The average particle diameter of the obtained resin particles was 1.2 mm.

(Impregnation step)
After 100 parts by weight of the resin particles were sealed in a pressure vessel and the inside of the pressure vessel was replaced with carbon dioxide gas, carbon dioxide gas was injected to an impregnation pressure (gauge pressure) of 0.7 MPa. It was left still in an environment of 20 ° C., and after 24 hours of impregnation, the pressure inside the pressure vessel was slowly released over 5 minutes. In this way, the resin particles were impregnated with carbon dioxide gas to obtain expandable particles.
(Foaming process)
Immediately after the pressure reduction in the impregnation step, the expandable particles were taken out of the pressure vessel, and then 0.1 parts by weight of ethylenebisstearic acid amide was added and mixed. Thereafter, the impregnated material was foamed with steam in a high-pressure foaming tank while stirring at a foaming temperature of 143 ° C. for 50 seconds using steam. After foaming, drying was performed with a flash dryer to obtain foamed particles. When the bulk density of the obtained expanded particles was measured by the method described above, it was 102 kg / m ³ (expansion ratio: 10 times).
(Molding process)
The obtained foamed particles were allowed to stand at room temperature (23 ° C.) for one day, then sealed in a pressure vessel, and the inside of the pressure vessel was replaced with carbon dioxide gas. It was press-fitted to 5 MPa. It was left still in an environment of 20 ° C., and pressure curing was performed for 8 hours. After taking out, filling a molding die of 30 mm x 300 mm x 400 mm, heating with steam of 0.38 MPa for 20 seconds, and then cooling until the maximum surface pressure of the foamed molded product is reduced to 0.05 MPa. Thus, a foam molded article was obtained.

(Example 2)
In the (foaming step), a foaming density of 74 kg / cm 2 was obtained in the same manner as in Example 1 except that 0.15 parts by weight of ethylenebisstearic acid amide was added and foaming was carried out with stirring at a foaming temperature of 143 ° C. for 55 seconds. As a result, foamed particles having a m ³ (expansion ratio of 15 times) and a foamed molded article were obtained.
Table 1 shows the physical properties of the foamed particles and foamed molded products of Examples 1 and 2 described above.
FIG. 1 shows cross-sectional photographs of the expanded particles and the expanded molded articles of Examples 1 and 2.

  From Table 1, it can be seen that the foamed molded article obtained from the foamed particles having a specific range of cells has excellent mechanical properties.

(Example 3)
(Resin particle manufacturing process)
Styrene-methyl methacrylate-maleic anhydride copolymer (trade name “DENKA RESISTY R-200”, manufactured by Denka Co., Ltd., styrene: 55 parts by weight, methyl methacrylate: 26 parts by weight, maleic anhydride: 19 parts by weight, density 1.16 g / cm ³ ) of 100 parts by weight was supplied at a rate of 10 kg / hr per hour to a single-screw extruder having a diameter of 40 mm and melt-kneaded at 260 ° C. Subsequently, cooling water of about 70 ° C. was supplied from a die hole (five nozzles having a diameter of 0.8 mm) of a die (temperature: 280 ° C., resin pressure at the entrance side: 14 MPa) mounted on the tip of the single screw extruder. The resin particles are extruded into the housed chamber, and the rotary shaft of a rotary blade having six cutting blades is rotated at a rotation speed of 5000 rpm, cut into granules, cooled with the cooling water, and dehydrated and dried to obtain resin particles. Produced. The average particle diameter of the obtained resin particles was 1.2 mm.

(Impregnation step)
After 100 parts by weight of the resin particles were sealed in a pressure vessel and the inside of the pressure vessel was replaced with carbon dioxide gas, carbon dioxide gas was injected to an impregnation pressure (gauge pressure) of 0.7 MPa. It was left still in an environment of 20 ° C., and after 24 hours of impregnation, the pressure inside the pressure vessel was slowly released over 5 minutes. In this way, the resin particles were impregnated with carbon dioxide gas to obtain expandable particles.
(Foaming process)
Immediately after the pressure reduction in the impregnation step, the expandable particles were taken out of the pressure vessel, and then 0.1 parts by weight of ethylenebisstearic acid amide was added and mixed. Thereafter, the impregnated material was foamed with steam in a high-pressure foaming tank while stirring at a foaming temperature of 131 ° C. for 50 seconds using steam. After foaming, drying was performed with a flash dryer to obtain foamed particles. When the bulk density of the obtained expanded particles was measured by the method described above, it was 105 kg / m ³ (expansion ratio: 10 times).
(Molding process)
The obtained foamed particles were allowed to stand at room temperature (23 ° C.) for one day, then sealed in a pressure vessel, and the inside of the pressure vessel was replaced with carbon dioxide gas. It was press-fitted to 5 MPa. It was left still in an environment of 20 ° C., and pressure curing was performed for 8 hours. After taking out, filling a molding die of 30 mm × 300 mm × 400 mm, heating with steam of 0.30 MPa for 20 seconds, and then cooling until the maximum surface pressure of the foamed molded product is reduced to 0.05 MPa. Thus, a foam molded article was obtained.
Table 2 shows the physical properties of the foamed particles and the foamed molded product of Example 3 described above.
FIG. 2 shows a cross-sectional photograph of the expanded particles and the expanded molded article of Example 3.

  From Table 2, it can be seen that the foamed molded article obtained from the foamed particles having the cells in the specific range has excellent mechanical properties.

(Example 4)
(Resin particle manufacturing process)
Styrene-methyl methacrylate-maleic anhydride copolymer (trade name “DENKA RESISTY R-310”, manufactured by Denka Co., Ltd., styrene: 62 parts by weight, methyl methacrylate: 12 parts by weight, maleic anhydride: 26 parts by weight, density 1.15 g / cm ³ ) 100 parts by weight was 85 parts by weight, and the remaining 15 parts by weight was a styrene-maleic anhydride-N-phenylmaleimide copolymer (trade name “DENKA IP MS-NIP”, manufactured by Denka Co., Ltd.) Styrene: 58 parts by weight, maleic anhydride: 4 parts by weight, N-phenylmaleimide: 38 parts by weight, density 1.18 g / cm ³ , glass transition temperature Tg 186 ° C.) The mixture was supplied to a single-screw extruder having a diameter of 40 mm at a ratio and melt-kneaded at 270 ° C. Subsequently, cooling water of about 70 ° C. was supplied from a die hole (five nozzles having a diameter of 0.8 mm arranged) of a die (temperature: 285 ° C., resin pressure at the inlet side: 14 MPa) mounted on the tip of the single screw extruder. The resin particles are extruded into the housed chamber, and the rotary shaft of a rotary blade having six cutting blades is rotated at a rotation speed of 5000 rpm, cut into granules, cooled with the cooling water, and dehydrated and dried to obtain resin particles. Produced. The average particle diameter of the obtained resin particles was 1.2 mm.

(Impregnation step)
After 100 parts by weight of the resin particles were sealed in a pressure vessel and the inside of the pressure vessel was replaced with carbon dioxide gas, carbon dioxide gas was injected to an impregnation pressure (gauge pressure) of 0.7 MPa. It was left still in an environment of 20 ° C., and after 24 hours of impregnation, the pressure inside the pressure vessel was slowly released over 5 minutes. In this way, the resin particles were impregnated with carbon dioxide gas to obtain expandable particles.
(Foaming process)
Immediately after the pressure reduction in the impregnation step, the expandable particles were taken out of the pressure vessel, and then 0.1 parts by weight of ethylenebisstearic acid amide was added and mixed. Thereafter, the impregnated material was foamed with steam in a high-pressure foaming tank while stirring at a foaming temperature of 145 ° C. for 80 seconds using steam. After foaming, drying was performed with a flash dryer to obtain foamed particles. When the bulk density of the obtained expanded particles was measured by the method described above, it was 104 kg / m ³ (expansion ratio: 10 times).
(Molding process)
The obtained foamed particles were allowed to stand at room temperature (23 ° C.) for one day, then sealed in a pressure vessel, and the inside of the pressure vessel was replaced with carbon dioxide gas. It was press-fitted to 5 MPa. It was left still in an environment of 20 ° C., and pressure curing was performed for 8 hours. After taking out, filling in a molding die of 30 mm x 300 mm x 400 mm, heating with 0.45 MPa steam for 20 seconds, and then cooling until the maximum surface pressure of the foamed molded product is reduced to 0.05 MPa. Thus, a foam molded article was obtained.

(Example 5)
In the (foaming step), a foaming density of 72 kg / kg was obtained in the same manner as in Example 6, except that 0.15 parts by weight of ethylenebisstearic acid amide was added and foaming was performed with stirring at a foaming temperature of 145 ° C. for 90 seconds. As a result, foamed particles having a m ³ (expansion ratio of 15 times) and a foamed molded article were obtained.
Table 3 shows the physical properties of the foamed particles and foamed molded products of Examples 4 and 5 above.
FIG. 3 shows cross-sectional photographs of the foamed particles and the foamed molded products of Examples 4 and 5.

  From Table 3, it can be seen that the foamed molded product obtained from the foamed particles having the cells in the specific range has excellent mechanical properties.

(Comparative Example 1)
In the (foaming step), a foaming density of 61 kg / kg was obtained in the same manner as in Example 1 except that 0.15 parts by weight of ethylenebisstearic acid amide was added, and foaming was performed with stirring at a foaming temperature of 143 ° C. for 60 seconds. m ³ (expansion ratio 20 times) expanded particles and expanded molded articles were obtained.

(Comparative Example 2)
In the (foaming step), a foaming density of 52 kg / kg was obtained in the same manner as in Example 3 except that 0.15 parts by weight of ethylenebisstearic acid amide was added, and foaming was performed with stirring at a foaming temperature of 131 ° C. for 70 seconds. m ³ (expansion ratio 20 times) expanded particles and expanded molded articles were obtained.

(Comparative Example 3)
In the (foaming step), a foaming density of 47 kg / kg was obtained in the same manner as in Example 4 except that 0.15 parts by weight of ethylenebisstearic acid amide was added and foaming was performed with stirring at a foaming temperature of 145 ° C. for 100 seconds. m ³ (expansion ratio 20 times) expanded particles and expanded molded articles were obtained.

(Comparative Example 4)
(Resin particle manufacturing process)
Styrene-methyl methacrylate-maleic anhydride copolymer (trade name “DENKA RESISTY KX-406”, manufactured by Denki Kagaku Kogyo KK), styrene: 70 parts by weight, methyl methacrylate: 9 parts by weight, maleic anhydride: 21 parts by weight , A density of 1.15 g / cm ³ ) and 100 parts by weight of talc-containing resin composition were fed to a twin screw extruder having a diameter of 30 mm and melt-kneaded at 254 ° C. Subsequently, the resin composition was extruded from each nozzle of a multi-nozzle mold (20 nozzles each having a diameter of 1.0 mm and arranged in a circle) attached to the front end of the twin-screw extruder. The extruded resin was immediately cooled in a cooling water bath. Then, the cooled strand-shaped resin was sufficiently drained, and cut into small particles using a pelletizer to produce resin particles. The obtained resin particles had a particle length L of 1.3 to 1.8 mm and a particle diameter D of 1.0 to 1.2 mm.

(Impregnation step)
After 100 parts by weight of the resin particles were sealed in a pressure vessel and the inside of the pressure vessel was replaced with carbon dioxide gas, carbon dioxide gas was injected to an impregnation pressure of 1.0 MPa. It was left still in an environment of 20 ° C., and after 24 hours of impregnation, the pressure inside the pressure vessel was slowly released over 5 minutes. In this way, the resin particles were impregnated with carbon dioxide gas to obtain expandable particles.
(Foaming process)
Immediately after the pressure reduction in the impregnation step, the expandable particles were taken out of the pressure vessel, and 0.08 parts by weight of calcium carbonate was added and mixed. Thereafter, the impregnated material was foamed with steam in a high-pressure foaming tank while stirring at a foaming temperature of 136 ° C. for 150 seconds using steam. After foaming, the particles were taken out of the high-pressure foaming tank, and after removing calcium carbonate with a hydrogen chloride aqueous solution, drying was performed with a flash dryer to obtain foamed particles. When the bulk density of the obtained expanded particles was measured by the method described above, it was 104 kg / m ³ . When a cross-sectional photograph of the expanded particles was confirmed, no large bubbles were present.

(Molding process)
After leaving the obtained foamed particles at room temperature (23 ° C.) for one day, they are sealed in a pressure vessel, and the inside of the pressure vessel is replaced with carbon dioxide gas. Then, the carbon dioxide gas is impregnated (gauge pressure) to 0.4 MPa. Pressed. It was left still in an environment of 20 ° C., and pressure curing was performed for 8 hours. After taking out, filling in a molding die of 30 mm x 300 mm x 400 mm, heating with 0.42 MPa steam for 60 seconds, and then cooling until the maximum surface pressure of the foamed molded product is reduced to 0.01 MPa. Thus, a foam molded article was obtained.
Table 4 shows the physical properties of the foamed particles and foamed molded products of Comparative Examples 1 to 4.
FIG. 4 shows cross-sectional photographs of the foamed particles and the foamed molded products of Comparative Examples 1 to 3.

Claims (9)

Expanded particles composed of a base resin containing a copolymer of aromatic vinyl, a (meth) acrylic acid ester and an unsaturated dicarboxylic acid, wherein the expanded particles have an area of 11.9 mm ² at 30 times. In the cross-sectional photograph taken, is provided a small bubble having a bubble diameter of 50 μm or more and less than 300 μm and a large bubble having a bubble diameter of 300 μm or more and 2 mm or less, and the difference between the average bubble diameter of the small bubble and the average bubble diameter of the large bubble Is not less than 1000 μm and less than 1500 μm, and the foamed particles give a foamed molded article composed of the fused body a maximum point stress by a bending test of 1.0 MPa or more.   The foamed particle of claim 1, wherein the foamed particle has, in one of them, only one of the large cells.   The aromatic vinyl is a styrene monomer, the (meth) acrylate is an alkyl (meth) acrylate (the alkyl group has 1 to 5 carbon atoms), and the unsaturated dicarboxylic acid is a 2 to 6 carbon atom. Aliphatic unsaturated dicarboxylic acid, respectively, the copolymer is 100 parts by weight of the total of the units derived from the aromatic vinyl, (meth) acrylic acid ester and unsaturated dicarboxylic acid three, 30 to 80 parts by weight of the unit derived from the aromatic vinyl, 8 to 35 parts by weight of the unit derived from the (meth) acrylate, and 10 to 50 parts by weight of the unit derived from the unsaturated dicarboxylic acid. The expanded particles according to claim 1. An expanded molded article composed of a base resin containing a copolymer of an aromatic vinyl, a (meth) acrylate and an unsaturated dicarboxylic acid, wherein the expanded molded article is composed of a plurality of expanded particles. In the cross-sectional photograph in which the foamed particles have an area of 11.9 mm ^{2 at} a magnification of 30 times, small bubbles having a bubble diameter of 50 μm or more and less than 300 μm and large bubbles having a bubble diameter of 300 μm or more and 2 mm or less are provided. The difference between the average cell diameter of the cells and the average cell diameter of the large cells is not less than 1000 μm and less than 1500 μm, and the expanded particles are the maximum by a bending test of 1.0 MPa or more on a foamed molded article composed of the fused body. A foam molded article characterized by applying a point stress.   The foamed molded article according to claim 4, wherein the foamed particle has, in one of them, only one large cell.   The aromatic vinyl is a styrene monomer, the (meth) acrylate is an alkyl (meth) acrylate (the alkyl group has 1 to 5 carbon atoms), and the unsaturated dicarboxylic acid is a 2 to 6 carbon atom. Aliphatic unsaturated dicarboxylic acid, respectively, the copolymer is 100 parts by weight of the total of the units derived from the aromatic vinyl, (meth) acrylic acid ester and unsaturated dicarboxylic acid three, 30 to 80 parts by weight of the unit derived from the aromatic vinyl, 8 to 35 parts by weight of the unit derived from the (meth) acrylate, and 10 to 50 parts by weight of the unit derived from the unsaturated dicarboxylic acid. The foamed molded article according to claim 4.   A fiber-reinforced composite comprising the foamed molded article according to any one of claims 4 to 6, and a fiber-reinforced plastic layer laminated and integrated on the surface of the foamed molded article.   The fiber-reinforced composite according to claim 7, which is used for a windmill blade, a robot arm, and an automobile part.   An automotive part comprising the foam molded article according to any one of claims 4 to 6 or the fiber reinforced composite according to claim 7.