JP2018175601A - Composite mold and manufacturing method thereof, and seat cushion core material for vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a composite mold made up of a synthetic resin foam particle mold and a reinforced member buried therein by an insert molding, a manufacturing method of the composite mold, and a seat cushion core material for vehicle made up of the composite mold, which shows less warpage and exhibits excellent dimension accuracy.SOLUTION: Provided are a composite mold 10 made up of a synthetic resin foam particle mold 2 and a reinforced member 3 buried therein by an insert molding, a manufacturing method of the composite mold, and a seat cushion core material 1 for vehicle made up of the composite mold 10. The synthetic resin comprising the synthetic resin foam particle mold 2 is a composite resin prepared by an impregnated polymerization of a styrene-based monomer into a polyolefin-based resin. The composite resin contains a composition derived from the styrene-based monomer in an amount of 250 to 500 parts by mass based on 100 parts by mass of composition derived from the polyolefin-based resin.SELECTED DRAWING: Figure 5

Description

  The present invention relates to a composite molded body comprising a synthetic resin foamed particle molded body and a reinforcing member embedded in the molded body, a method for producing the same, and a vehicle seat cushion core material comprising the composite molded body.

  In recent years, as a sheet core material used for a vehicle seat member such as a vehicle seat cushion and a seat back, a composite molded body made of a synthetic resin foamed particle molded body and a reinforcing member embedded in the inside is used. The reinforcing member is, for example, an annular frame member made of metal, and is embedded for attachment to a vehicle body or reinforcement at the time of a collision.

  Such a composite molded body is manufactured, for example, by insert molding. Specifically, first, a reinforcing member is disposed at a predetermined position in a mold, and then synthetic resin foam particles are filled in the mold and heated. As a result, the foamed particles are fused to each other to obtain a synthetic resin foamed particle molded body, and the reinforcing member is embedded and integrated in the molded body.

  In general, since the synthetic resin foam particle molded body causes molding shrinkage after in-mold molding, the shape is stabilized at a size smaller than the mold size. Therefore, when the foamed particle molded body and the reinforcing member are integrally formed by insert molding or the like, the composite molded body is formed after the molding due to the difference in shrinkage ratio between the foamed particle molded body and the reinforcing member. In some cases, warpage occurred. When a composite molded body having such a warp is used as a sheet core material, there is a possibility that the mounting accuracy to a vehicle body may be deteriorated, or a desired performance may not be obtained.

  As a measure for solving these problems, a divided space is provided in the foamed particle molded body so that the annular frame member is exposed, and the divided space causes the foamed particle molded body to contract independently to stabilize its size. A method has been proposed (see, for example, Patent Document 1).

International Publication WO2016 / 152530

  However, according to the proposal of Patent Document 1, since the foamed particle molded body is a completely divided structure, each can be contracted independently, while lacking in the overall sense of unity as a sheet core material, at the time of handling There is a problem that the sheet core material is bent or deformed. Therefore, development of means for reducing the difference in shrinkage rate between the foamed particle molded body and the reinforcing member is desired from a completely different approach.

  The present invention has been made in view of such background, and it is a composite molded body which can exhibit excellent dimensional accuracy with little warpage even when manufactured by insert molding, a method of manufacturing the same, and a vehicle seat cushion core comprising the composite molded body. It is intended to provide materials.

One aspect of the present invention is a composite molded body comprising a synthetic resin foam particle molded body and a reinforcing member embedded by insert molding in the molded body,
The synthetic resin constituting the above synthetic resin foamed particle molded body is a composite resin obtained by impregnating and polymerizing a styrene-based monomer with a polyolefin-based resin,
The composite resin is a composite molded body including a component derived from the styrene-based monomer in a ratio of 250 to 500 parts by mass with respect to 100 parts by mass of the component derived from the polyolefin-based resin.

  Another aspect of the present invention is a vehicle seat cushion core material comprising the above-mentioned composite molded body.

Yet another aspect of the present invention is a method for producing a composite molded body comprising a synthetic resin foam particle molded body and a reinforcing member embedded in the molded body,
A foaming step of obtaining synthetic resin foamed particles by foaming synthetic resin particles having as a base resin a composite resin formed by impregnating and polymerizing a styrene-based monomer with a polyolefin-based resin;
Insert molding in which the synthetic resin foam particles are fused to one another by heating the synthetic resin foam particles in a mold in which the reinforcing member is disposed, to obtain the composite molded body,
A composite molded article, wherein the composite resin of the synthetic resin particles contains a component derived from the styrene-based monomer in a ratio of 250 to 500 parts by mass with respect to 100 parts by mass of the component derived from the polyolefin-based resin It is in the manufacturing method.

  The composite molded body is composed of a synthetic resin foamed particle molded body and a reinforcing member embedded in the molded body by insert molding. Hereinafter, the synthetic resin foamed particle molded body is appropriately referred to as "foamed particle molded body". The foamed particle molded body is composed of a composite resin obtained by impregnating and polymerizing a styrene-based monomer with a polyolefin-based resin. That is, the base resin of the foamed particles is made of the above composite resin. The component derived from the polyolefin resin and the component derived from the styrenic monomer in the composite resin are adjusted within the predetermined range as described above.

  Such a composite molded body has less warpage after in-mold molding and can exhibit excellent dimensional accuracy. Therefore, the seat cushion core material for a vehicle, which is a composite molded body, can obtain desired dimensional accuracy, high attachment accuracy to a vehicle body, and desired performance as a seat cushion.

  The composite molded body is obtained by performing the foaming step and the insert molding step as described above. By adjusting the addition amount of the styrene-based monomer to be impregnated and polymerized in the polyolefin-based resin, as described above, the component derived from the predetermined range of the polyolefin-based resin and the component formed by the polymerization of the styrene-based monomer By performing the foaming step and the insert molding step using synthetic resin particles in which the composite resin is used as the base resin, as described above, the occurrence of warpage of the molded composite can be sufficiently suppressed.

  As described above, according to the present invention, there is provided a composite molded article comprising a synthetic resin foam particle molded article which is less warped and can exhibit excellent dimensional accuracy, and a reinforcing member embedded by insert molding in this molded body, The manufacturing method and the seat cushion core material for vehicles which consist of a composite-molding object can be provided.

The figure which shows the transmission electron micrograph in the center part cross section of the expandable synthetic resin particle used for manufacture of the sample E in an experiment example. The figure which shows the transmission electron micrograph in the center part cross section of the expandable synthetic resin particle used for manufacture of the sample C1 in an experiment example. The figure which shows the transmission electron microscope photograph in center part cross section of the foamable synthetic resin particle used for manufacture of sample C2 in an experiment example. FIG. 1 is a perspective view schematically showing a seat cushion core material for a vehicle according to a first embodiment. Explanatory drawing which shows the embedding state of the reinforcement member in the foaming particle molded body of the seat cushion core material for vehicles in Example 1 by a top view. VI-VI arrow directional cross-sectional view in FIG. Explanatory drawing which shows the measurement position of the displacement amount in the seat cushion core material for vehicles in Example 1 by a top view Explanatory drawing which shows the position of the slit in the seat cushion core material for vehicles in Example 2 by a top view. Explanatory drawing (a) which shows the position of the penetration type | mold slit of the seat cushion core material for vehicles in Example 3 by a top view, b1-b1 arrow directional cross-sectional view in (a). Explanatory drawing (a) which shows the non-penetration type slit position in the seat cushion core material for vehicles in Example 3 with a top view, b2-b2 arrow directional cross-sectional view in (a). Explanatory drawing (a)-(e) which shows each modification of the slit position in the seat cushion core material for vehicles in Example 3 by a top view.

Next, a preferred embodiment of a composite molded body, a method of manufacturing the same, and a seat cushion core material for a vehicle will be described.
The composite molded body has a foamed particle molded body and a reinforcing member. Generally, a foamed particle molded body having a synthetic resin as a base resin shrinks substantially uniformly after molding to cause molding shrinkage in which the size is smaller than the size of a mold. This molding shrinkage appears notably when crystalline thermoplastic resin is used as a base resin. The reinforcing member is usually made of a material different from that of the foamed particle molded body, and is made of a material such as metal or fiber reinforced plastic having high rigidity and relatively small molding shrinkage. When such a reinforcing member is insert-molded in a foamed particle molded body, the foamed particle molded body in the portion in which the reinforcing member is embedded is inhibited from shrinking, and the foamed particle in a portion in which the reinforcing member is not embedded As the body tries to shrink according to the normal rate of shrinkage, unequal shrinkage occurs in the foamed particle compact during shrinkage. Unequal shrinkage is, for example, shrinkage which is relatively unequal to uniform shrinkage when a compact having no reinforcing member shrinks. For example, since the shrinkage force of the foamed particle molded body of the conventional configuration is very strong, when the shrinkage force of the foamed particle molded body exceeds the rigidity of the reinforcing member, the reinforcing member itself is also deformed due to unequal shrinkage, and the composite molded body is warped. Occurs. On the other hand, the present disclosure relates to a composite molded body or the like that can exhibit such dimensional precision with less warpage and includes the following foamed particle molded bodies.

  In the foamed particle molded body, a large number of foamed particles are fused to each other, and the foamed particles are particulate foams having a synthetic resin as a base resin. And the synthetic resin which comprises a foaming particle molded object is a composite resin formed by impregnating and polymerizing a styrene-type monomer to polyolefin resin. This means that each foam particle which comprises a foam particle molded object makes composite resin a base resin.

  In the present specification, the composite resin is a resin obtained by impregnating and polymerizing a styrene-based monomer in a polyolefin-based resin as described above, and a component derived from a polyolefin-based resin and a component derived from a styrene-based monomer It is a contained resin. Usually, the main component of the component derived from the styrenic monomer is a styrenic resin formed by polymerization of the styrenic monomer.

  At the time of the polymerization of the styrene-based monomer, not only the polymerization of the styrene-based monomers, but also the graft polymerization of the styrene-based monomer may occur in the polymer chain constituting the olefin-based resin. In this case, the composite resin not only contains a polyolefin resin component and a polystyrene resin component formed by polymerization of a styrene monomer, but also a polyolefin resin component in which a styrene monomer is graft polymerized ( That is, it contains PO-g-PS component). In addition, crosslinking of the polyolefin resin may occur during polymerization of the styrene monomer. In this case, the composite resin contains, as a polyolefin resin component, a non-crosslinked polyolefin resin and a cross-linked polyolefin resin. Therefore, the composite resin is a concept different from a mixed resin obtained by melt-kneading a polymerized polyolefin resin and a polymerized polystyrene resin.

  The composite resin contains the component derived from the styrenic monomer in a ratio of 250 to 500 parts by mass with respect to 100 parts by mass of the component derived from the polyolefin resin. Even if it exceeds this range or falls below this range, the warpage of the molded composite will increase.

  From the viewpoint that warpage of the composite molded body can be further suppressed, the content of the component derived from the styrene-based monomer relative to 100 parts by mass of the component derived from the polyolefin-based resin is preferably 250 to 400 mass, 250 mass It is even more preferable that it is not less than part and less than 350 parts by mass.

  In addition, since the foamed particle molded body contains the composite resin adjusted to the predetermined composition ratio as described above, the composite molded body has excellent toughness, recoverability of the olefin resin, and excellent rigidity of the styrene resin. Can be combined. Therefore, the composite molded body is suitable for a vehicle member.

  Examples of polyolefin resins include linear low density polyethylene, high density polyethylene, ethylene-vinyl acetate copolymer, ethylene-acrylic acid copolymer, ethylene-acrylic acid alkyl ester copolymer, ethylene-methacrylic acid alkyl ester An ethylene-based resin such as a copolymer can be used. In addition, as the olefin resin, for example, propylene homopolymer (that is, polypropylene), propylene-ethylene copolymer, propylene-1-butene copolymer, propylene-ethylene-1-butene copolymer, propylene-4- A propylene-based resin such as a methyl-1-pentene copolymer can also be used. Moreover, as polyolefin resin, although 1 type of polymers may be sufficient, the mixture of 2 or more types of polymers can also be used.

  From the viewpoint that foamability can be improved and foam particles exhibit excellent in-mold moldability, and from the viewpoint that the composite resin before foaming tends to be a morphology of a bicontinuous structure described later, the polyolefin resin has a linear low density. It is preferable to have polyethylene as a main component. From the viewpoint of further enhancing these effects, the content of the linear low density polyethylene in the polyolefin resin is preferably 50% by mass or more, more preferably 60% by mass or more, and 70% by mass It is more preferable that it is more than.

  Moreover, it is preferable that polyolefin-type resin has linear low density polyethylene as a main component, and content of an ethylene-vinyl acetate copolymer is 5 mass% or less (however, 0 is included). In this case, the composite resin tends to have a bicontinuous structure in which both the polyolefin resin component and the component obtained by polymerizing the styrenic monomer have a continuous phase.

The density of the linear low density polyethylene resin is usually 0.88 to 0.945 g / cm ³ , preferably 0.88 to 0.94 g / cm ³ , more preferably 0.88 to 0.93 g / it is possible cm ^3. The linear low density polyethylene is a copolymer of ethylene and an α-olefin such as 1-butene or 1-hexene, and has a low density as described above.

  The melt mass flow rate (MFR: 190 ° C., load 2.16 kg) of the linear low density polyethylene resin is preferably 0.5 to 4.0 g / 10 min from the viewpoint of foamability, and 1.0 to 3.0 g / l. 10 minutes is more preferable. In addition, MFR of polyolefin resin is a value in the temperature of 190 degreeC, and the conditions of 2.16 kg of loads measured based on JISK7210-1: 2014. Further, as the measuring device, for example, a melt indexer such as model L203 manufactured by Takara Kogyo Co., Ltd. can be used. As the linear low density polyethylene, one using a metallocene polymerization catalyst is preferable.

  It is preferable that melting | fusing point Tm of polyolefin resin is 95 degreeC-115 degreeC. In this case, the polyolefin resin can be sufficiently impregnated with the styrene monomer, and the suspension system can be prevented from being destabilized during the polymerization. More preferably, it is good for Tm of polyolefin resin to be 100-110 ° C.

  The composite resin contains a component derived from a styrenic monomer. The styrenic monomer can include not only styrene but also monomers copolymerizable with styrene. Examples of monomers copolymerizable with styrene include styrene derivatives, other vinyl monomers, and the like. As a styrene derivative, α-methylstyrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, p-ethylstyrene, 2,4-dimethylstyrene, p-methoxystyrene, p-n-butylstyrene, p -T-butylstyrene, o-chlorostyrene, m-chlorostyrene, p-chlorostyrene, 2,4,6-tribromostyrene, divinylbenzene, styrene sulfonic acid, sodium styrene sulfonate and the like. These may be used alone or as a mixture of two or more.

  Also, as other vinyl monomers, acrylic esters such as butyl acrylate, methacrylic esters such as methyl methacrylate, vinyl compounds containing hydroxyl groups such as acrylic acid, methacrylic acid, and hydroxyethyl acrylate, nitriles such as acrylonitrile Group-containing vinyl compounds, organic acid vinyl compounds such as vinyl acetate, olefin compounds such as ethylene and propylene, diene compounds such as butadiene and isoprene, vinyl halide compounds such as vinyl chloride, and vinylidene halide compounds such as vinylidene chloride Maleimide compounds, such as N-phenyl maleimide, etc. are mentioned. These vinyl monomers may be used alone or in combination of two or more.

  From the viewpoint of enhancing the foamability, it is preferable to use styrene alone as the styrene monomer or to use styrene and an acrylic monomer in combination. From the viewpoint of further enhancing the foamability, it is more preferable to use styrene and butyl acrylate as the styrene-based monomer. In this case, the content of the butyl acrylate component in the composite resin is preferably adjusted to 0.5 to 10% by mass, and more preferably adjusted to 1 to 8% by mass, It is further preferable to adjust to 2 to 5% by mass. Further, from the viewpoint of enhancing the heat resistance of the composite molded body, it is preferable to use styrene and methacrylic acid, and styrene and α-methylstyrene in combination. In this case, the content of methacrylic acid and / or α-methylstyrene in the styrenic monomer is preferably 0.5 to 20% by mass.

  The synthetic resin foam particles constituting the synthetic resin foam particle molded body are based on a composite resin having a morphology in which both a component derived from a polyolefin resin and a component obtained by polymerizing a styrenic monomer are a continuous phase. It is preferable to be made of foamed particles obtained by foaming synthetic resin particles to be a material resin. A composite resin having such a bicontinuous morphology is considered to be sufficiently plastically deformed during primary foaming or secondary foaming during in-mold molding. Therefore, it is considered that the contraction force applied to the foamed particle molded body becomes small after the foaming and the molding, and the contraction rate becomes sufficiently small. As a result, it is considered that the occurrence of warpage of the molded composite can be more effectively suppressed.

  In addition, the composite resin preferably contains a dispersion diameter expanding agent. In this case, the composite resin before foaming tends to have a bicontinuous structure. As the dispersion diameter expanding agent, for example, an acrylonitrile-styrene copolymer, a (meth) acrylic acid alkyl ester-styrene copolymer and the like can be used. Preferably, the composite resin is an acrylonitrile-styrene copolymer and a (meth) acrylic acid alkyl ester relative to 100 parts by mass in total of the component derived from the polyolefin resin and the component derived from the styrene monomer. It is preferable to contain 1 to 10 parts by mass of at least one of the styrene copolymers. In this case, the composite resin containing the component derived from the styrenic monomer in a ratio of 250 to 500 parts by mass with respect to 100 parts by mass of the component derived from the polyolefin resin has a more bicontinuous structure before foaming. It becomes easy to become. Therefore, by using synthetic resin particles having such a composite resin as a base resin, warpage after molding of the composite molded body can be further reduced. The content of at least one of an acrylonitrile-styrene copolymer and a (meth) acrylic acid alkyl ester-sthrene copolymer is a total amount of 100 mass of a component derived from a polyolefin resin and a component derived from a styrene monomer. 5 parts by mass or less is more preferable, and 3 parts by mass or less is more preferable.

  The composite molded body is obtained by performing the foaming step and the insert molding step. In the foaming step, first, for example, 100 parts by mass of polyolefin resin particles are impregnated and polymerized with 250 to 500 parts by mass of a styrene-based monomer. Thereby, a synthetic resin particle can be obtained in which a composite resin containing a component derived from a polyolefin resin and a component obtained by polymerizing a styrene monomer is used as a base resin. The polyolefin resin particles are hereinafter referred to as “core particles” as appropriate. In addition, synthetic resin particles having a composite resin as a base resin can also be referred to as composite resin particles.

In order to obtain synthetic resin particles, for example, first, core particles containing a polyolefin resin as a main component are dispersed in a liquid such as an aqueous medium to prepare a dispersion. The core particles may further contain additives such as a cell regulator, a colorant, a flame retardant, a lubricant, an antioxidant, a weathering agent, and a dispersion diameter expanding agent, in addition to the polyolefin resin. The core particle can be produced by blending the above-mentioned additive, which is added as necessary, to the polyolefin resin, and melt-kneading the blend with an extruder or the like and then granulating.
Granulation of core particles can be performed by, for example, a strand cut method, an underwater cut method, a hot cut method or the like.

  As an aqueous medium, for example, deionized water can be used. The core particles are preferably dispersed in an aqueous medium with the suspending agent. In this case, the styrenic monomer can be uniformly suspended in the aqueous medium. As the suspending agent, for example, a particulate inorganic suspending agent such as tricalcium phosphate, hydroxyapatite, magnesium pyrophosphate and the like can be used. For example, organic suspending agents such as polyvinyl alcohol can also be used. Preferably, tricalcium phosphate, hydroxyapatite and magnesium pyrophosphate are preferable. These suspending agents can be used alone or in combination of two or more.

  The amount of the suspending agent used is a solid content of 0. 0 with respect to 100 parts by mass of an aqueous medium of the suspension polymerization system (specifically, all water in the system containing water such as a reaction product-containing slurry). 05-10 mass parts are preferable. More preferably, it is 0.3 to 5 parts by mass.

  To the aqueous medium, a dispersing agent consisting of a surfactant can be added. As surfactant, anionic surfactant, nonionic surfactant, cationic surfactant, amphoteric surfactant etc. can be used, for example. These surfactants can be used alone or in combination of two or more.

  Preferably, an anionic surfactant is used as the surfactant. More preferably, a C8 to C20 alkyl sulfonic acid alkali metal salt is preferable, and a sodium salt is preferable.

  Further, in order to obtain a molded article having better toughness and mechanical strength, it is preferable to add a water-soluble polymerization inhibitor to the aqueous medium. As the water-soluble polymerization inhibitor, for example, sodium nitrite, potassium nitrite, ammonium nitrite, L-ascorbic acid, citric acid and the like can be used. From the viewpoint of reducing the amount of the styrenic resin component in the vicinity of the outermost surface of the synthetic resin particle composed of the composite resin, the amount of the water-soluble polymerization inhibitor added is an aqueous medium (specifically, water such as a reaction product-containing slurry) Preferably, the amount is 0.001 to 0.1 parts by mass, and more preferably 0.005 to 0.06 parts by mass with respect to 100 parts by mass of all water in the system including

  Next, in order to obtain synthetic resin particles, the styrene particles are impregnated into core particles in an aqueous medium and polymerized. The polymerization of the styrenic monomer can be carried out in the presence of a polymerization initiator. In this case, in addition to the polymerization of the styrene-based monomer, the crosslinking of the polyolefin-based resin such as the polyethylene-based resin may occur. Moreover, a crosslinking agent can be used together separately as needed. When using a polymerization initiator and a crosslinking agent, it is preferable to previously dissolve the polymerization initiator and the crosslinking agent in the styrenic monomer.

  As a polymerization initiator, what is used for the suspension polymerization method of a styrene-type monomer can be used. For example, a polymerization initiator which is soluble in a styrenic monomer and has a one-hour half-life temperature of 70 to 140 ° C. can be used. As a polymerization initiator, for example, lauroyl peroxide, t-butylperoxy-2-ethylhexanoate, benzoyl peroxide, hexylperoxyisopropyl carbonate, 1,1-bis-t-butylperoxycyclohexane, t-amyl Organic peroxides such as peroxy-2-ethylhexyl carbonate, t-butylperoxyisopropyl carbonate, hexylperoxybenzoate, t-butylperoxy-2-ethylhexyl carbonate, t-butylperoxybenzoate, dicumyl peroxide and the like It can be used. In addition, as the polymerization initiator, an azo compound such as azobisisobutyronitrile, 1,1′-azobis (cyclohexane-1-carbonitrile) and the like can be used. These polymerization initiators can be used alone or in combination of two or more. Further, from the viewpoint of easily impregnating the styrene-based monomer to the inside of the core particle, a polymerization initiator having a one-hour half-life temperature of 100 to 140 ° C. is preferable, and dicumyl peroxide is preferably used. The polymerization initiator is preferably used in an amount of 0.01 to 3 parts by mass with respect to 100 parts by mass of the styrenic monomer.

  Moreover, as a crosslinking agent, it is preferable to use a 1-hour half-life temperature crosslinking agent of 110-160 degreeC. Specifically, for example, t-butylperoxy-2-ethylhexyl carbonate, t-butylperoxybenzoate, dicumyl peroxide, 2,5-dimethyl-2,5-di (t-butylperoxy) hexane, di- Peroxides such as t-butyl peroxide can be used. The crosslinking agents can be used alone or in combination of two or more. It is preferable that the compounding quantity of a crosslinking agent is 0.1-5 mass parts with respect to 100 mass parts of styrene-type monomers. In addition, the same compound can also be employ | adopted as a polymerization initiator and a crosslinking agent.

  When the core particles are impregnated with the styrene-based monomer and polymerized, the total amount of the styrene-based monomer to be blended is divided, for example, into 2 or more in an aqueous medium in which the core particle is dispersed, and these monomers are different It is preferable to add at timing. Specifically, a part of the total amount of the styrenic monomer to be blended is added to the aqueous medium in which the core particles are dispersed to impregnate and polymerize the styrenic monomer, and then, Furthermore, the remainder of the styrenic monomer to be compounded can be added to the aqueous medium in one or more portions.

  The polymerization initiator can be added to the aqueous medium in the state of being dissolved in the styrenic monomer. As described above, when the styrene-based monomer to be blended is divided into two or more times and added at different timings, the polymerization initiator should be dissolved in the styrene-based monomer added at any timing. The polymerization initiator can be added to each styrenic monomer added at different timings. When the styrenic monomer is divided and added, it is preferable to dissolve a polymerization initiator in at least the styrenic monomer (hereinafter, referred to as "first monomer") to be added first.

  The seed ratio of the styrenic monomer added as the first monomer (that is, the mass ratio of the first monomer to the core particles) is preferably 0.5 or more. In this case, even when the proportion of the styrene-based resin component in the composite resin is high, it is possible to suppress that the addition amount of the second monomer is too large. And the styrenic resin component on the particle surface can be reduced. Moreover, it becomes easy to make the shape of the synthetic resin particle which consists of composite resin more nearly spherically. From the same viewpoint, the seed ratio is more preferably 0.7 or more, further preferably 0.8 or more. The seed ratio is preferably 1.5 or less. In this case, even if the ratio of the component derived from the styrenic monomer in the composite resin is high, the impregnability of the styrenic monomer can be enhanced, and the styrenic monomer can be used as core particles. It can be fully impregnated. In addition, it is possible to further prevent the polymerization of the styrenic monomer before the core particles are sufficiently impregnated, and to further prevent the generation of a lump of resin. From the same viewpoint, the seed ratio of the first monomer is more preferably 1.3 or less, and still more preferably 1.2 or less.

  The impregnation temperature and the polymerization temperature vary depending on the type of the polymerization initiator to be used, but are preferably 60 to 105 ° C., and more preferably 70 to 105 ° C. The crosslinking temperature varies depending on the type of crosslinking agent used, but is preferably 100 to 150 ° C. The impregnation temperature of the styrene-based monomer is a temperature at which the polyolefin-based resin is impregnated with the styrene-based monomer. The polymerization temperature is a temperature at which the polymerization of the styrene-based monomer impregnated in the polyolefin-based resin is allowed to proceed.

  Further, to the styrene-based monomer, a cell regulator, a plasticizer, an oil-soluble polymerization inhibitor, a flame retardant, a colorant, a chain transfer agent and the like can be added.

In the foaming step, synthetic resin particles are foamed. Thereby, synthetic resin foam particles are obtained. In the present specification, synthetic resin foam particles are appropriately referred to as "foam particles". For foaming, conventionally known foaming methods can be applied. Specifically, for example, a synthetic resin particle is dispersed in a dispersion medium such as water in a pressure container together with a foaming agent, and heated to soften the resin particle and impregnate the synthetic resin particle with the foaming agent, and then the synthetic resin is produced. A method (hereinafter, also referred to as a direct foaming method) can be used in which synthetic resin particles are released together with a dispersion medium at a temperature lower than the interior of the container (for example, normal atmospheric pressure) at a temperature higher than the softening temperature of the particles. . Alternatively, for example, a method may be used in which foamable synthetic resin particles containing a foaming agent are taken out from a closed container, and the foamable synthetic resin particles are heated and foamed with a heating medium such as steam. The bulk density of the expanded beads is preferably from 10 to 50 kg / m ^3, more preferably 20~40kg / m ^3.

  In the insert molding step, the foam particles are heated in a mold in which the reinforcing member is disposed. As a result, a large number of foam particles are fused to each other to obtain a foam particle molded body, and the foam particle molded body and the reinforcing member are integrated, and a composite molded body in which the reinforcing member is embedded in the foam particle molded body You can get it. Heating of the foam particles is performed, for example, by introducing steam into the mold.

The apparent density of the foamed particle compact is preferably 10 to 50 kg / m ³ . From the viewpoint of providing a vehicle seat cushion core material excellent in balance between strength and lightness, the apparent density of the foamed particle molded body is more preferably 20 to 40 kg / m ³ . In general, the warpage of the composite molded body tends to be larger as the apparent density of the foamed particle molded body is lower, so that the above-described effect of the warpage suppression is easily exhibited. In addition, a plurality of foamed particle compacts having different apparent densities can be combined to form one foamed particle compact. In this case, the average apparent density of the entire foamed particle compact may be within the above numerical range. In addition, the apparent density used here can be calculated | required by the submergence method which is made to submerge and measure a foaming particle molded object.

  The reinforcing member is not particularly limited as long as it is used as a reinforcing member of a seat cushion core material for a vehicle, for example, a metal reinforcing member made of iron, aluminum, copper or the like, engineering plastic, glass fiber reinforced resin, etc. And the like. Among these, metal is preferable in terms of strength and the like. The shape thereof is preferably linear, tubular, or rod-like, and preferably 2 to 20 mm in diameter.

  Further, the shape of the reinforcing member is not particularly limited as long as it is a shape that functions as attachment to a vehicle body or reinforcement at the time of a collision, but it is preferable that the reinforcing member is embedded along at least one side of the foamed particle molded body It is further preferable to be embedded along at least the longitudinal side of the foamed particle molded body. The length of the reinforcing member is preferably 30% or more and 50% or more when the length of the side of the portion in which the reinforcing member is embedded is 100%. Is more preferred.

  Preferably, the reinforcing member is an annular wire frame member having, for example, a front frame portion, a rear frame portion, and two side frame portions connecting the front frame portion and the rear frame portion. In this case, for example, the vehicle seat cushion core material can be attached to the vehicle body at the front frame portion, and the vehicle seat cushion core material can be attached to the back seat by the rear frame portion. Further, the seat cushion core material for a vehicle can be reinforced by the annular wire frame member. In order to enhance the reinforcing effect, it is preferable that the annular wire frame member be embedded in the peripheral portion of the synthetic resin foam particle molded body.

The reinforcing member may have an exposed portion exposed from the foamed particle molded body. When the reinforcing member is an annular wire frame member and the annular wire frame member is embedded in the peripheral portion of the synthetic resin foam particle molded body, the range covering 50% or more of the reinforcing member is embedded when the total length of the reinforcing member is 100%. It is preferable to be embedded in a range of 70% or more, and more preferable to be embedded in a range of 90% or more.
The term “embedded” means that, when the shape of the reinforcing member is linear, tubular or rod-like, the reinforcing member is surrounded by foamed particle molding in a direction perpendicular to the axial direction of the reinforcing member. Do. In this case, there may be a slight gap between the foamed particle molded body and the reinforcing member. Moreover, exposure means the state in which at least one part of a reinforcement member can be visually recognized from the outside.

  The seat cushion core material for a vehicle, which is a composite molded body, preferably has a slit formed so as to relieve unequal shrinkage during molding shrinkage of the synthetic resin foam particle molded body. That is, it is preferable to have a slit that can reduce unequal contraction. In this case, the warpage of the composite molded body can be further suppressed. for that reason. The seat cushion core material for a vehicle can be further improved in the mounting accuracy to the vehicle body, and can exhibit desired performance more reliably.

  The formation pattern of the slits is not particularly limited as long as the unequal shrinkage can be alleviated as described above, but it will be exemplified in the examples described later. The slits may penetrate through the seat cushion core material for a vehicle in the thickness direction, or may be non-penetrating recessed grooves (that is, bottomed grooves).

[Example of experiment]
In this example, a plurality of foamed particle compacts (Sample E, Sample C1, Sample C2) used for the composite compact are manufactured, and characteristics such as the shrinkage rate are evaluated. In each expanded particle molded body, a large number of expanded particles having a composite resin as a base resin are fused to each other. The composite resin is formed by impregnating and polymerizing a styrene-based monomer to a polyolefin-based resin at a predetermined ratio. Hereinafter, the manufacturing method of each foaming particle | grain molded object is demonstrated.

[1] Production of Sample E (1-1) Production of Core Particles As a polyolefin resin, a linear low density polyethylene (“Nipolone Z 9P51A” manufactured by Tosoh Corporation) was prepared by polymerization using a metallocene polymerization catalyst. Further, as a dispersion diameter expanding agent, acrylonitrile-styrene copolymer ("AS-XGS manufactured by Denki Kagaku Kogyo Co., Ltd., weight average molecular weight: 109,000, acrylonitrile content: 28% by mass, MFR (200 ° C, load) 5 kg): 2.8 g / 10 min) 20 kg of linear low density polyethylene resin and 1 kg of dispersion diameter expanding agent were charged into a Henschel mixer and mixed for 5 minutes to obtain a resin mixture. The resin mixture is called resin a. MFR with a temperature of 190 ° C. and a load of 2.16 kg of resin a is shown in Table 1. In addition, as a Henschel mixer, Mitsui is Using a pond Chemical Engineering Co., Ltd. of the type FM-75E.

  Next, this resin mixture was melt-kneaded at a temperature of 230 to 250 ° C. with an extruder, and cut into an average of 0.5 mg / piece by a cut-in-water method to obtain core particles containing a polyolefin resin. As an extruder, a single-screw extruder with an inner diameter of 50 mm was used.

(1-2) Preparation of foamable synthetic resin particles 1000 g of deionized water was added to an autoclave with an internal volume of 3 L with a stirrer, and 6.0 g of sodium pyrophosphate was further added, and then powdered magnesium nitrate. 12.9 g of hexahydrate was added and stirred at room temperature for 30 minutes. Thus, a magnesium pyrophosphate slurry as a suspending agent was produced. Next, 1.5 g of sodium lauryl sulfonate (10% by mass aqueous solution) as a surfactant, 0.5 g of sodium nitrite as a water-soluble polymerization inhibitor, and 125 g of core particles were added to the suspension.

  Then, 1.29 g of benzoyl peroxide as a polymerization initiator, 2.58 g of t-butylperoxy-2-ethylhexyl monocarbonate, 0.86 g of dicumyl peroxide as a crosslinking agent, 245 g of styrene as a monomer, and acrylic The dissolved product was poured into a suspension in an autoclave while being dissolved in 15 g of butyl acid and stirring at a stirring speed of 500 rpm. As benzoyl peroxide, a water-diluted powder product of Nippon Oil and Fats Co., Ltd. “Nyper BW” was used. As t-butylperoxy-2-ethylhexyl monocarbonate, “Perbutyl E” manufactured by NOF Corporation was used. As the dicumyl peroxide, "Parkmill D" manufactured by NOF Corporation was used.

  Next, after the air in the autoclave was replaced with nitrogen, temperature rising was started, and the temperature was raised to a temperature of 88 ° C. over 1 hour and 30 minutes. After raising the temperature, the temperature was maintained at 88 ° C. for 30 minutes, and then the stirring speed was reduced to 450 rpm. It cooled to 88 degreeC-80 degreeC over 30 minutes, and hold | maintained this polymerization temperature at 80 degreeC for 8 hours. When reaching 80 ° C., 115 g of styrene as a monomer was added to the autoclave over 3 hours.

  Then, the temperature was raised to 125 ° C. over 4 hours, and the temperature was kept at 125 ° C. for 2 hours and 30 minutes. Thereafter, it was cooled to a temperature of 90 ° C. for 1 hour, the stirring speed was lowered to 400 rpm, and maintained at a temperature of 90 ° C. for 3 hours. Then, when the temperature reached 90 ° C., 20 g of cyclohexane and 65 g of butane (specifically, a mixture of about 20% by volume of normal butane and about 80% by volume of isobutane) were added to the autoclave over about 1 hour. Further, the temperature was raised to 105 ° C. over 2 hours, maintained at 105 ° C. for 5 hours as it is, and then cooled to 30 ° C. for about 6 hours.

After cooling, the contents were taken out and nitric acid was added to dissolve magnesium pyrophosphate attached to the surface of the resin particles. Thereafter, the mixture was dewatered and washed by a centrifugal separator, and water attached to the surface was removed by a flash dryer to obtain foamable synthetic resin particles having an average particle diameter d ₆₃ of about 1.6 mm.

  The obtained expandable synthetic resin particles are sieved to take out particles having a diameter of 0.7 to 2.0 mm, and 100 parts by mass of the expandable synthetic resin particles is N, N-bis (2 as an antistatic agent). 0.008 parts by mass of (hydroxyethyl) alkylamine was added, and further coated with a mixture of 0.12 parts by mass of zinc stearate, 0.04 parts by mass of glycerol monostearate and 0.04 parts by mass of glycerol distearate.

  Next, with respect to the expandable synthetic resin particles obtained as described above, the morphology, gel amount, glass transition temperature (Tg) of polystyrene resin, and weight average molecular weight (Mw) of polystyrene resin are set as follows. I examined it. The results are shown in Table 2 below. In Table 2, the above-mentioned polyolefin resin is described as polyethylene resin.

"Morphology"
A sample for observation was cut out from the center of the expandable synthetic resin particles. The observation sample was embedded in an epoxy resin, stained with ruthenium tetraoxide, and then ultra-thin sections were prepared by an ultramicrotome. The ultra-thin sections were placed on a grid, and the morphology of the central cross section of the expandable synthetic resin particles was observed with a transmission electron microscope at a magnification of 10000 and a cross-sectional photograph (that is, a TEM photograph) was taken. As a transmission electron microscope, JEM 1010 manufactured by JEOL Ltd. was used. The results are shown in FIG. In the figure, the dark gray part is a polyolefin resin and the light gray part is a polystyrene resin. The same applies to FIGS. 2 and 3 described later. As shown in FIG. 1, in the foamable synthetic resin particle of this example, the morphology is such that it becomes a bicontinuous structure (that is, a sea-sea structure) in which both the polyolefin resin of the composite resin and the polystyrene resin are continuous phases. It was In addition, in the same figure, the salami-like site | part which exists in the phase (light gray phase) of a polystyrene-type resin is a dispersion diameter expansion agent which consists of an acrylonitrile styrene copolymer.

"Xylene insolubles (gel amount)"
First, about 1.0 g of precisely weighed expandable synthetic resin particles was placed in a 150 mesh wire mesh bag. Next, about 200 ml of xylene was placed in a 200 ml round flask, and a sample of the expandable synthetic resin particles placed in the above-mentioned wire mesh bag was set in a Soxhlet extraction tube. Soxhlet extraction was performed by heating with a mantle heater for 8 hours, and after completion of the extraction, it was cooled by air cooling. Next, about 600 ml of acetone was placed in a 1000 ml beaker, and the acetone was used to wash the sample in the wire gauze removed from the extraction tube after the extraction was completed. Then, after evaporating acetone, the sample was dried for 4 hours in an oven at a temperature of 120.degree. The residual content was defined as gel content, and the ratio of the gel content (mass) to the initial amount of foamable synthetic resin particles (mass) was expressed as a percentage, and this was defined as the gel content (mass%) insoluble in xylene.

"Glass transition temperature (Tg) of polystyrene resin"
First, about 1.0 g of expandable synthetic resin particles was placed in a 150 mesh wire mesh bag. Next, about 200 ml of xylene was placed in a 200 ml round flask, and a sample of the expandable synthetic resin particles placed in the above-mentioned wire mesh bag was set in a Soxhlet extraction tube. Soxhlet extraction was performed by heating with a mantle heater for 8 hours. The xylene solution extracted here was dropped into 600 ml of acetone, decanted and evaporated to dryness under reduced pressure to obtain a polystyrene resin as an acetone-soluble component. Heat flux differential scanning calorimetry was performed on 2 to 4 mg of the obtained polystyrene resin. The heat flux differential scanning calorific value was measured according to JIS K 7121 (1987) using a 2010 type DSC measuring instrument manufactured by TA Instruments. Then, the midpoint glass transition temperature of the DSC curve obtained under the conditions of a heating rate of 10 ° C./min was determined, and this was used as the glass transition temperature (Tg) of the polystyrene resin.

"Weight-average molecular weight of polystyrene resin (Mw)"
First, in the same manner as described above, a polystyrene resin was obtained from the foamable synthetic resin particles as an acetone-soluble component. The weight average molecular weight of the obtained polystyrene resin was measured by gel permeation chromatography (GPC) method (mix gel column for polymer measurement) using polystyrene as a standard substance. Specifically, a measuring device manufactured by Tosoh Corp. (GPC-8020
The measurement can be performed using Model II) under the following measurement conditions: eluent: tetrahydrofuran (THF), flow rate: 2 ml / min, column: TSK-GEL GMH manufactured by Tosoh Corporation. The weight average molecular weight was determined by dissolving a polystyrene resin in tetrahydrofuran, measuring by gel permeation chromatography (GPC), and calibrating with standard polystyrene.

(1-3) Production of Expanded Particles Next, expanded particles were produced using the expandable synthetic resin particles obtained as described above. Specifically, first, the expandable synthetic resin particles obtained as described above were placed in a 30 L normal pressure batch foaming machine, and steam was supplied into the foaming machine. Thereby, the foamable synthetic resin particles were foamed to a bulk density of about 25 kg / m ³ to obtain composite resin foam particles.

The bulk density (kg / m ³ ) of the composite resin foam particles is prepared by preparing a 1 L measuring cylinder, placing the composite resin foam particles up to the 1 L mark line in an empty measuring cylinder, and placing it in the measuring cylinder. It calculated | required by measuring the weight of particle | grains. The bulk density (kg / m ³ ) of the composite resin foam particles was calculated by converting the weight of the foam particles per 1 L of bulk volume obtained by this operation into a unit.

(1-4) Preparation of Foamed Particle Molded Body The foamed particles obtained above were aged at room temperature for 1 day, and then molded into a rectangular solid of 300 mm × 75 mm × 25 mm with a mold for forming a molded body. . As a mold molding machine, VS-500 manufactured by Daisen Industries, Ltd. was used. The mold size is 300 mm × 75 mm × 25 mm as in the case of the molded body. Thus, the foamed particles were respectively molded to obtain a foamed particle molded body having an apparent density of 25 kg / m ³ . The apparent density (unit: kg / m ³ ) of the foamed particle molded body was calculated by dividing the mass of the molded body by the volume of the molded body obtained by the water immersion method. The results are shown in Table 2.

  Next, for the foamed particle molded body, the compressive stress and the contraction rate after 7 days after molding were measured. The results are shown in Table 2.

"Compressive stress"
Test pieces of 50 mm long, 50 mm wide, and 25 mm thickness were cut out from the composite resin foam particle molding, and a compression test was performed using the test pieces according to JIS K 7220 (2006). The compressive stress at 50% compressive strain was taken as 50% compressive stress (MPa).

"Shrinkage rate after molding"
The foamed particle compact immediately after molding was dried at a temperature of 60 ° C. for 3 hours and then left at a temperature of 23 ° C. for 7 days. After that, the dimensional shrinkage was calculated from the following equation. L is the length in the foamed particle compact corresponding to a length of 300 mm in the mold dimension.
Dimension shrinkage rate = (300-L) × 100/300

[2] Production of Sample C1 Sample C1 is an example of a foamed particle molded body having a composition of the composite resin different from that of the sample E.

(2-1) Preparation of core particles Linear low-density polyethylene ("Nipolone Z 9 P 51 A" manufactured by Tosoh Corp., 15 kg of a polymer based on a metallocene catalyst as a polyolefin resin and Tosoh Corp., which is an ethylene-vinyl acetate copolymer) The mixture was charged with Henschel mixer (Mitsui Miike Kako Co., Ltd .; model FM-75E) and mixed for 5 minutes, and the resin mixture of the compound used here was designated as resin b. MFR of resin b (190 ° C., 2.16 kg load) is shown in the following Table 1. Core particles were produced in the same manner as in sample E using this resin mixture.

(2-2) Preparation of Expandable Synthetic Resin Particles First, in the same manner as in the case of sample E, a magnesium pyrophosphate slurry as a suspending agent was prepared in an autoclave with an internal volume of 3 L attached with a stirrer. Next, 1.5 g of sodium lauryl sulfonate (10% by mass aqueous solution) as a surfactant, 0.15 g of sodium nitrite as a water-soluble polymerization inhibitor, and 150 g of core particles were added to the suspension.

  Next, 1.72 g of benzoyl peroxide as a polymerization initiator ("Nyper BW" manufactured by NOF Corp., water-diluted powder product) and 1.29 g of t-butylperoxy-2-ethylhexyl monocarbonate (NOF Corp.) Product "Perbutyl E") and 0.43 g of dicumyl peroxide ("Parkmill D" manufactured by Nippon Oil and Fats Co., Ltd.) as a cross-linking agent are dissolved in 335 g of styrene as a monomer and 15 g of butyl acrylate The mixture was charged into the suspension in the autoclave while being stirred at 500 rpm.

  Next, after the air in the autoclave was replaced with nitrogen, temperature rising was started, and the temperature was raised to a temperature of 87 ° C. over 1 hour and 30 minutes. After raising the temperature, the temperature was maintained at 87 ° C. for 30 minutes, and then the stirring speed was reduced to 450 rpm. The polymerization temperature was maintained at 87 ° C. for 6 hours.

  Then, the temperature was raised to 125 ° C. over 4 hours, and the temperature was kept at 125 ° C. for 2 hours and 30 minutes. Thereafter, it was cooled to a temperature of 90 ° C. for 1 hour, the stirring speed was lowered to 400 rpm, and maintained at a temperature of 90 ° C. for 3 hours. Then, when the temperature reached 90 ° C., 20 g of cyclohexane and 65 g of butane (a mixture of about 20% by volume of normal butane and about 80% by volume of isobutane) were added to the autoclave over about 1 hour as a foaming agent. Further, the temperature was raised to 105 ° C. over 2 hours, maintained at 105 ° C. for 5 hours as it is, and then cooled to 30 ° C. for about 6 hours.

After cooling, the contents were taken out, dewatered and washed in the same manner as in sample E, and expandable synthetic resin particles having an average particle diameter (d ₆₃ ) of about 1.6 mm were obtained. The morphology of the cross section of the central portion of the expandable synthetic resin particles obtained in this example was observed in the same manner as in sample E with a transmission electron microscope at a magnification of 10000 and a cross-sectional photograph was taken. The results are shown in FIG. As shown in FIG. 2, in the foamable synthetic resin particles of this example, the morphology is shown as a sea-island structure in which a discontinuous phase consisting of a polystyrene based resin is dispersed in a continuous phase consisting of a polyolefin based resin of a composite resin. The discontinuous phase is also referred to as the dispersed phase.

  The obtained expandable synthetic resin particles were sieved in the same manner as in sample E, and particles with a diameter of 0.7 to 2.0 mm were taken out. Further, it was coated with an antistatic agent in the same manner as in sample E and was coated with a mixture of zinc stearate, glycerin monostearate and glycerin distearate.

  Using the foamable synthetic resin particles obtained as described above, foam particles were produced in the same manner as in sample E, and a foam particle molded body was produced using the foam particles. With respect to the foamed particles and the foamed particle molded body, the same physical properties as those of the sample E were measured and evaluated. The results are shown in Table 2.

[3] Production of Sample C2 Sample C2 is a foamed particle molded body having a composition of the composite resin different from that of Sample E and Sample C1.
Specifically, first, in the same manner as sample E, core particles using resin a were produced. Further, in the same manner as in sample E, a magnesium pyrophosphate slurry as a suspending agent was prepared in an autoclave with an internal volume of 3 L attached with a stirrer.

  Subsequently, 1.25 g of sodium lauryl sulfonate (10% by mass aqueous solution) as a surfactant, 0.15 g of sodium nitrite as a water-soluble polymerization inhibitor, and 75 g of core particles were added to the suspension.

  Next, 1.715 g of t-butylperoxy-2-ethylhexyl monocarbonate ("Perbutyl E" manufactured by NOF Corporation) as a polymerization initiator was dissolved in the first monomer (styrene-based monomer). Then, the lysate was poured into the suspension in the autoclave while stirring at a stirring speed of 500 rpm. A mixed monomer of 60 g of styrene and 15 g of butyl acrylate was used as the first monomer.

  Then, after the air in the autoclave was replaced with nitrogen, the temperature was raised to 100 ° C. over 1 hour and 30 minutes. After the temperature rise, the temperature was maintained at 100 ° C. for 60 minutes. Thereafter, the stirring speed was lowered to 450 rpm and maintained at a polymerization temperature of 100 ° C. for 7 hours and 30 minutes. Incidentally, 350 g of styrene as a second monomer (a styrenic monomer) was added to the autoclave over 5 hours when 60 minutes had passed since the temperature reached 100 ° C.

  Then, the temperature was raised to 125 ° C. over 2 hours, and the temperature was maintained at 125 ° C. for 5 hours. Thereafter, it was cooled to a temperature of 90 ° C. for 1 hour, the stirring speed was lowered to 400 rpm, and maintained at a temperature of 90 ° C. for 3 hours. Then, when the temperature reaches 90 ° C., 20 g of cyclohexane, 15 g of pentane (a mixture of about 80% by weight of normal pentane and about 20% by weight of isopentane) as an organic physical blowing agent, and butane (about 20% by weight of normal butane, about 80 isobutane) 50 g of a mixture of wt%) was added to the autoclave over about 1 hour. Further, the temperature was raised to 105 ° C. over 2 hours, maintained at 105 ° C. for 5 hours as it is, and then cooled to 30 ° C. for about 6 hours.

After cooling, the contents were taken out and nitric acid was added to dissolve magnesium pyrophosphate attached to the surface of the resin particles. Thereafter, the mixture was dewatered and washed by a centrifuge, and water attached to the surface was removed by a flash dryer to obtain expandable synthetic resin particles having an average particle diameter (d ₆₃ ) of about 1.7 mm. The morphology of the cross section of the central portion of the expandable synthetic resin particles obtained in this example was observed in the same manner as in sample E with a transmission electron microscope at a magnification of 10000 and a cross-sectional photograph was taken. The results are shown in FIG. As shown in FIG. 3, in the foamable synthetic resin particles of this example, the morphology is shown as a sea-island structure in which a non-continuous phase consisting of a polystyrene based resin is dispersed in a continuous phase consisting of a polyolefin based resin of a composite resin. In addition, in the same figure, the salami-like site | part which exists in the phase (light gray phase) of a polystyrene-type resin is a dispersion diameter expansion agent which consists of an acrylonitrile styrene copolymer.

  Further, in the same manner as in sample E, an antistatic agent (N, N-bis (2-hydroxyethyl) alkylamine) is added to the obtained foamable synthetic resin particles, and zinc stearate, glycerin monostearate, And coated with a mixture of glycerine distearate. Thus, expandable synthetic resin particles were produced.

  Using the foamable synthetic resin particles obtained in this example, foam particles and a foam particle molded body were produced in the same manner as in Sample E. With respect to the foamed particles and the foamed particle molded body, the same physical properties as those of the sample E were measured and evaluated. The results are shown in Table 2.

  As is known from Table 2, a sample using, as a base resin, a composite resin containing a component derived from a styrenic monomer in a ratio of 250 to 500 parts by mass with respect to 100 parts by mass of a component derived from a polyolefin resin As for E, it turns out that a contraction rate is greatly small compared with sample C1 and sample C2 from which a styrenic monomer goes out of the above-mentioned range. That is, the foamed particle molded body of sample E is unlikely to change in dimension even if time passes after molding.

  By the way, when sample C1 and sample C2 are compared, the dimensional shrinkage is smaller as the content of the component derived from the styrenic monomer is smaller, so the shrinkage as the content of the component derived from the styrenic monomer is larger Is expected to decrease. However, when the samples C2 and E are compared, the smaller the component derived from the styrenic monomer, the smaller the dimensional shrinkage, which is also significantly smaller. This means that there is a specific composition range for significantly reducing the foamed particle compact. Then, as in sample E, foaming using a composite resin containing a component derived from a styrene-based monomer in a ratio of 250 to 500 parts by mass with respect to 100 parts by mass of a component derived from a polyolefin-based resin as a base resin Particulate compacts, as is known from Table 2, allow the dimensional shrinkage to be significantly reduced.

  Therefore, as shown in Example 1 and Example 2 described below, by making the reinforcing member embedded in the foamed particle molded body of Sample E by insert molding to form a composite molded body, the occurrence of warpage can be suppressed, and the dimensional accuracy can be reduced. High composite moldings can be obtained. Such a composite molded body is suitable, for example, as a seat cushion core material for a vehicle, and can be attached to a vehicle body, a seat back, or the like with high attachment accuracy.

[Examples and Comparative Examples]
Example 1
This example is an example of a cushion core material for a vehicle, which is a composite molded body. First, the core material according to the first embodiment will be described. As illustrated in FIGS. 4 to 6, the vehicle seat cushion core 1 is composed of a composite molded body 10 having a foamed particle molded body 2 and a reinforcing member 3 embedded therein by insert molding. The foamed particle molded body 2 is substantially the same as the sample E produced in Experimental Example 1 except for the shape. The annular reinforcing member 3 embedded in the foamed particle molded body 2 should not be originally shown in FIG. 5, but is shown for convenience of explanation. In practice, the reinforcing member 3 is embedded in the foamed particle molded body 2 as illustrated in FIG.

  The seat cushion core 1 for a vehicle in this example can be used as a cushion core of a rear seat of a car. In the following description, “forward” means the direction of the seat cushion core that corresponds to the front of the vehicle in a state where the seat cushion core is attached to the vehicle. "Backward" means the direction opposite to the above "forward". Further, “sideward” means the direction of the seat cushion core material corresponding to the width direction of the vehicle. Further, the upper surface means the surface on the seat surface side of the seat cushion core material for a vehicle, and the "lower surface" means the surface on the opposite side of the upper surface.

  The foamed particle molded body 2 in the seat cushion core 1 for a vehicle has a long side and a short side, and has a rectangular shape in top view. The rectangular shape means that the whole is rectangular in appearance in top view, and may have a partially recessed portion or a protruding portion.

  A reinforcing member 3 is embedded in the peripheral portion of the foamed particle molded body 2. The reinforcing member 3 is preferably an annular wire frame member. In this case, as shown in FIG. 5, when the seat cushion core 1 for a vehicle is viewed from above, each side and four corners of the seat cushion core 1 for a vehicle can be reinforced. In addition, the whole of the annular reinforcing member 3 may be embedded in the foamed particle molded body 2, but a part of the reinforcing member 3 may be exposed from the foamed particle molded body 2.

  The reinforcing member 3 illustrated in FIG. 5 is made of a metal wire member having a thickness of about 4.5 mm, and has a substantially rectangular ring shape. The maximum length in the longitudinal direction is 1200 mm, and the maximum length in the lateral direction is 550 mm. The reinforcing member 3 has front and rear halves that are different in shape between front and rear halves. When the shape of the reinforcing member 3 is asymmetrical, unequal shrinkage tends to occur in the foamed particle molded body after molding. Hereinafter, the front side portion of the annular frame 3 is also referred to as a front frame portion 31, the rear side portion as a rear frame portion 32, and the side portion as a side frame portion 33.

  In the vicinity of both ends of the front frame portion 31 of the reinforcing member 3, two metal hooks 3a for attachment to the vehicle body are coupled. The rear frame portion 32 of the reinforcing member 3 is coupled with two metal hooks 3b for connecting to the back sheet. The number of hooks 3a and 3b is not particularly limited.

  The dimensions of the foamed particle molded body 2 can be appropriately changed according to the vehicle to be mounted, but generally, the length in the longitudinal direction is adjusted to about 1000 to 1500 mm and the length in the short direction to about 400 to 700 mm. The thickness may be in the range of 5 to 200 mm, and may not necessarily be uniform. The foamed particle molded body 2 is a thick portion having a thickness greater than that of the surroundings, and a thickness having a thickness smaller than that of the surroundings You may have a part. The maximum thickness is 200 mm or less, preferably 150 mm or less. In addition, "thickness" means the length of the up-down direction of the foaming particle molded body in the body which attached the seat cushion core material to the vehicle.

  Next, the manufacturing method of the seat cushion core material for vehicles which consists of a composite-molding object of this example is explained. The seat cushion core material for a vehicle is manufactured by insert molding as follows.

First, foamed particles having a bulk density of 25 kg / m ³ obtained in the same manner as the sample E in the above-mentioned experimental example were prepared. Subsequently, a mold for molding the seat cushion core material for a vehicle was prepared, and the reinforcing member shown in FIG. 5 was disposed in the mold. Next, the foam particles were filled in a mold and heated to further heat the foam particles by supplying steam. Thus, the foamed particles are fused to each other to form a foamed particle molded body, and the foamed particle molded body and the reinforcing member are integrated. After this molded body was released from the mold, it was aged for 24 hours in an atmosphere of 60 ° C. to obtain a vehicle seat cushion core material made of a composite molded body. This core material is Example 1. The obtained core material had a maximum length of 1250 mm in the longitudinal direction, a maximum length of 580 mm in the lateral direction, and a maximum thickness of 80 mm. Further, the apparent density of the foamed particle compact was 25 kg / m ³ .

  As illustrated in FIGS. 4 to 6, in the seat cushion core 1 for a vehicle according to the present embodiment, foam formed by fusion of foam particles using the same composite resin as the sample E described above as a base resin A particle compact 2 is provided, and a reinforcing member 3 is embedded in the periphery of the foamed particle compact 2. Further, the reinforcing member 3 is embedded in the lower surface side of the foamed particle molded body 2. Usually, when the embedded position of the reinforcing member 3 deviates from the center in the thickness direction of the foamed particle molded body 2 to the lower surface side in this way, the lower surface side of the foamed particle molded body 2 is inhibited from shrinking and the upper surface side is molded Since the contraction rate is intended to shrink, unequal contraction appears prominently. On the other hand, the foamed particle molded body 2 similar to the sample E has a very small shrinkage rate after molding as shown in the above-mentioned experimental example. Therefore, the foamed particle molded body 2 in the seat cushion core material 1 of the present example is not easily shrunk after molding, and the difference in shrinkage ratio between the foamed particle molded body 2 and the reinforcing member 3 is reduced. Therefore, it is hard to generate curvature in a seat cushion core material for vehicles, and it can attach to a vehicle body, a seat back, etc. precisely. As a result, the seat cushion core material for vehicles can exhibit desired performance.

  The vehicle seat cushion core material described above is attached to the vehicle body, but a soft synthetic resin foam such as urethane foam is laminated on the upper surface and the side surface of the vehicle seat cushion core material. Furthermore, the seat for a vehicle is formed by covering the outer peripheral surfaces such as the front surface, the side surfaces, and the upper portion of the laminate with a surface material such as woven and knitted fabric, vinyl leather, and leather.

  Soft synthetic resin foam refers to soft foam urethane mainly used as a material for seat cushions, or resin foam different from soft foam urethane and made to be soft by raising the foaming ratio and foaming. Means The use amount of the soft synthetic resin foam can be reduced by using the vehicle seat cushion core material made of the composite molded body as in this example. As a result, it is possible to form a vehicle seat that is excellent in lightness.

  Next, the displacement amount of the seat cushion core material for a vehicle which was left for 7 days in an atmosphere of 23 ° C. after curing was measured. The amount of displacement measured four measurement sites A to D shown in FIG. For measurement, using a measuring jig, the core material was supported at three points Rp in FIG. 7, and displacement amounts from the reference position were measured at the measurement sites A to D, respectively. Specifically, the displacement amount (that is, the warpage width) of each measurement site after 7 days of aging with respect to each measurement site in the vehicle seat cushion core material immediately after molding was determined. The results are shown in Table 3. In addition, when the measurement site | part was displaced upward from the reference position, it was described as "+", and when displaced downward, it was described as "-".

(Example 2)
Next, as illustrated in FIG. 8, the foamed particle molded body 2 and the reinforcing member 3 are formed of the composite molded body 10 having the same shape as in Example 1, and the foamed particle molded body 2 is formed at the time of molding shrinkage. An example of the seat cushion core 1 for a vehicle having the slits 4 formed to reduce unequal shrinkage will be described. In the following description, the same reference numerals as used in the previously described embodiments and the like denote the same components and the like as those in the previously described embodiments unless otherwise indicated.

  The core material 1 of this example is obtained in the same manner as in Example 1 to obtain the composite molded body 10, and immediately after the composite molded body 10 is released from the mold, as shown in FIG. A plurality of slits 4 were formed in The slits 4a and 4b penetrate from the upper surface to the lower surface of the vehicle seat cushion core 1 in the thickness direction and extend in the front-rear direction of the vehicle. The slits 4a and 4b are formed along the extension direction of the side frame portion 33 at a distance d1 of 20 mm inward from the rear portion of the side frame portion 33. Both ends in the extending direction of the slits 4a and 4b are provided at positions at a distance d2 = 20 mm inward from the front frame portion 31 and the rear frame portion 32, respectively. Further, as shown in FIG. 8, the slit 4 c penetrates in the thickness direction from the upper surface to the lower surface of the seat cushion core 1 for a vehicle and extends in the width direction of the vehicle. The slit 4 c is formed along the extending direction of the rear frame portion 32 at a distance d 3 = 100 mm inward from the central portion of the rear frame portion 32. Both ends in the extension direction of the slit 4c are provided at positions 50 mm inward of the slits 4a and 4b.

  After the formation of the slits 4a, 4b and 4c described above, curing was performed at 60 ° C. for 24 hours, and a vehicle seat cushion core 1 consisting of the composite molded body 10 was obtained. Also for the seat cushion core material of the present example, as in Example 1, the displacement amount after 7 days of aging at each measurement site was measured. The results are shown in Table 3.

(Comparative example 1)
A vehicle seat cushion core material similar to that of Example 1 described above was produced using the foamed particles having a bulk density of 25 kg / m ³ obtained in the same manner as the sample C1 in the experimental example. This core material is Comparative Example 1. Also for the core material of this example, as in Example 1, the displacement amount after 7 days of aging at each measurement site was measured. The results are shown in Table 3.

(Comparative example 2)
Using the foam particles having a bulk density of 25 kg / m ³ obtained in the same manner as the sample C 2 in the experimental example, a vehicle seat cushion core material similar to that of the above-mentioned Example 1 was produced. Also for the core material of this example, as in Example 1, the displacement amount after 7 days of aging at each measurement site was measured. The results are shown in Table 3.

(Comparative example 3)
A vehicle seat cushion core material similar to that of the above-described Example 1 was manufactured using foamed particles having a bulk density of 30 kg / m ³ and a polypropylene resin as a base resin. A commercially available product was used as the foamed particles having a polypyrrolene resin as a base resin. Specifically, a pea block manufactured by JSP Corporation was used. Also for the core material of this example, as in Example 1, the displacement amount after 7 days of aging at each measurement site was measured. The results are shown in Table 3.

(Comparison between Example and Comparative Example)
The comparison results of Example 1, Example 2, and Comparative Examples 1 to 3 are as follows.

  As known from Table 3, the seat cushion core materials of Examples 1 and 2 have a smaller warpage width than Comparative Examples 1 to 3. This is because Examples 1 and 2 are provided with the foamed particle molded body having a small shrinkage rate after molding, similarly to the sample E in the experimental example. Therefore, a composite resin containing a component derived from a styrene-based monomer in a ratio of 250 to 500 parts by mass with respect to 100 parts by mass of a component derived from a polyolefin-based resin as a foamed particle molded body of a seat cushion core material for vehicles It turns out that it is suitable to use what makes a base-material resin. In this case, the mounting accuracy to a vehicle body etc. can be improved, and desired performance can be exhibited as a seat cushion core material for a vehicle.

  Further, the vehicle seat cushion core material of the second embodiment has a smaller warpage width than that of the first embodiment. This is because Example 2 has a slit formed to reduce unequal shrinkage during molding shrinkage of the foamed particle molded body. In other words, by forming the slits in the foam particle molded body, it is possible to further suppress the warpage of the vehicle seat cushion core material.

(Example 3)
This example is an example which shows the variation of the slit 4 which can be formed in the foamed particle molded body 2 as illustrated in FIGS. 9 to 11. The slits 4 are formed to reduce unequal shrinkage at the time of molding shrinkage of the foamed particle molded body 2. The slit 4 can be formed, for example, in a portion where the shrinkage force of the foamed particle molded body 2 tends to be large.

  Specifically, for example, the slit 4 can be formed in a portion where the thickness of the foamed particle molded body 2 in which the contraction force tends to be large is large. Further, the slits 4 can be formed in a region close to the reinforcing member 3, and the slits 4 can be formed in the vicinity of the reinforcing member 3 in parallel with the extension direction of the reinforcing member 3. In addition, the slits 4 can be formed in the direction orthogonal to the extension direction of the reinforcing member 3. It is also possible to form a slit 4 which intersects the reinforcement member. The term “parallel” or “orthogonal” referred to here may be parallel or orthogonal as a whole in terms of appearance, and is a concept including those having a slight inclination from strict parallel or orthogonal.

  Preferably, slits 4 extending in the width direction of the vehicle and slits 4 extending in the front-rear direction of the vehicle can be formed. It is also possible to combine a plurality of slits 4.

  The dimensions such as the length, width, and depth of the slit 4 can be adjusted as appropriate. The length of the slit 4 is the length in the extension direction of the slit 4 in the seat surface of the seat cushion core 1 for a vehicle, and is preferably 50 mm or more, and more preferably 100 mm or more. The upper limit thereof is not particularly limited. For example, as illustrated in FIGS. 9A, 10A, and 11E, the seating surface is completely divided from end to end of the foamed particle molded body 2 It is also possible to form slits 4d, 4e, 4m, 4n of length.

  The width of the slit 4 is the length in the direction orthogonal to the extension direction, and is preferably 50 mm or less. Usually, the width of the slit is sufficiently smaller than the length in the extension direction. The lower limit of the width of the slit 4 is about 0.1 mm when the slit is formed by a cutter knife or the like after in-mold molding, and the width of the slit 4 is 10 mm or more when the slit 4 is formed during in-mold molding. It is preferable to

  The slits 4 may penetrate the thickness direction of the foamed particle molded body 2. That is, the slit 4 may penetrate in the thickness direction from the upper surface to the lower surface of the foamed particle molded body 2 of the seat cushion core 1 for a vehicle. Moreover, the slit 4 does not penetrate the foamed particle molded body 2 in the thickness direction, and may be a bottomed groove. That is, the slit is a concept including a through groove and a bottomed groove.

  From the viewpoint of sufficiently reducing the shrinkage and sufficiently suppressing the deformation of the seat cushion core 1 for a vehicle, the slit 4 has a thickness of the foamed particle molded body 3 in the thickness direction of the foamed particle molded body 2 from the upper surface It is preferable to provide about 50% or more of the above, and it is more preferable to provide about 80% or more. From the viewpoint of further suppressing deformation, it is more preferable that the slits 4 penetrate the foamed particle molded body 1.

  Hereinafter, the example of the slit 4 shown in FIGS. 9 to 11 will be described in more detail. In FIGS. 9 to 11, although the annular reinforcing member 3 embedded in the foamed particle molded body 2 should not be originally described, it is indicated by a broken line for convenience of describing the positional relationship with the slit 4. Is shown. In FIGS. 9A, 10A, and 11A to 11E, the upper part in the drawing sheet corresponds to the rear side, and the lower part corresponds to the front side.

  FIGS. 9 (a) and 9 (b) show an example of the slit 4d extending in the front-rear direction of the seat cushion core material for a vehicle. As illustrated in FIG. 9A, the slits 4 d are formed from the front to the back of the foamed particle molded body 2, and divide the foamed particle molded body 2. That is, the slit 4 d is formed from the front end to the rear end of the foamed particle molded body 2. Such a slit 4 d intersects with a pair of sides (that is, the front frame portion 31 and the rear frame portion 32) of the annular reinforcing member 3 extending in parallel with the vehicle width direction. Moreover, as illustrated in FIG. 9 (b), the slits 4 penetrate the foamed particle molded body 2 in the thickness direction.

  FIGS. 10A and 10B show an example of the slit 4 e extending in the front-rear direction of the seat cushion core 1 for a vehicle. The slits 4e are the same as the slits 4d described above in that they extend in the front-rear direction, but they do not penetrate the foamed particle molded body 2 in the thickness direction as illustrated in FIG. 10 (b). That is, the slit 4e is a bottomed groove formed to a predetermined depth from the upper surface. As exemplified in FIGS. 10 (a) and 10 (b), the slits 4e are non-penetrating bottomed grooves even though they are penetrating grooves penetrating the foamed particle molded body 2 in the thickness direction, It is also good.

  As illustrated in FIGS. 9A and 10A, the slits 4d and 4e extending in the front-rear direction of the seat cushion core 1 for a vehicle transmit the contraction force of the foamed particle molded body 2 in the width direction. Can ease things. Thereby, generation | occurrence | production of the curvature of the seat cushion core material 1 for vehicles can be suppressed more. Further, as in the case of the slit 4e illustrated in FIG. 10 (b), when the slit 4 is a bottomed groove, the foamed particle molded body 2 is not divided by the slit 4, so the sense of unity as the core material 1 is lost. Warpage of the core material 1 can be suppressed without.

  11 (a) to 11 (e) show further variations of the slit. In addition, the slit 4 of the shape shown to Fig.11 (a)-(e) may be a penetration type which penetrates the foaming particle molded object 2, and a non-penetration type may be sufficient as it.

FIG. 11 (a) shows an example of a slit 4f extending in the vehicle width direction. Both ends of the slit 4 f in the extension direction do not reach both lateral ends of the foamed particle molded body 2, and are formed inside the both ends. Furthermore, it is formed inside the annular reinforcing member 3 embedded in the foamed particle molded body 2. That is, both ends in the extension direction of the slit 4 f are formed at positions inward of the side frame portion 33 of the reinforcing member 3. The slits 4 are formed in the area on the rear side of the foamed particle molded body 2.
The slit 4 is formed along the rear side (that is, the rear frame portion 32) extending in the vehicle width direction in the annular reinforcing member 3 and is formed in the vicinity of this side and inside (front side) than this side It is done.

  FIG. 11 (b) shows an example of a plurality of slits 4g, 4h, 4i extending in the vehicle width direction. Thus, it is also possible to form a plurality of slits 4. The slits 4g, 4h, 4i are parallel to each other, and are all formed inside the annular reinforcing member 3 embedded in the foamed particle molded body 2. Further, the slits 4g, 4h, 4i are all formed in the area on the rear side of the seat cushion core 1 for a vehicle. The slits 4g and 4h are formed in parallel in the vehicle width direction, and the slits 4i are formed further inside (that is, on the front side) than the slits 4g and 4h. The slit 4i is formed such that the center of the slit 4i is disposed between two slits 4g and 4h located behind the slit 4i.

  FIG. 11C shows an example of the slit 4 j which extends in the vehicle width direction and in which both ends reach the outside of the annular reinforcing member 3. Both ends of the slit 4 j in the extension direction do not extend to both lateral ends of the foamed particle molded body 2, and are formed inside the both ends. However, compared with the slit 4f illustrated in FIG. 11A, the slit 4j is extended in the vehicle width direction at both ends and extends to the outside of the annular reinforcing member 3 embedded in the foamed particle molded body 2 . The slits 4 j are formed in the area on the rear side of the foamed particle molded body 2, and are formed inside the annular reinforcing member 3 in the front-rear direction.

  The seat cushion core 1 for a vehicle has a shape in which the thickness on the front side of the foamed particle molded body 2 is large and the thickness on the rear side is relatively small in order to suppress the submarine phenomenon at the time of collision. May have. The thick portion of the foamed particle molded body 2 has a relatively large contraction force, so that when the reinforcing member 3 is an annular wire frame member, the central portion of the rear frame portion 32 of the reinforcing member 3 is thick. By being pulled forward by the contraction of the part, the reinforcing member 3 is distorted, and as a result, the composite molded body 10 is easily warped. As illustrated in FIGS. 11 (a) to 11 (c), when the slit 4 extending in the width direction is formed in the rear region of the foamed particle molded body 2, the contraction of the foamed particle molded body 2 is transmitted in the front and back direction Can be relaxed. Thereby, generation | occurrence | production of the curvature of the seat cushion core material 1 for vehicles can be suppressed more.

  FIG. 11D shows an example of two slits 4k and 4l extending in the front-rear direction of the seat cushion core 1 for a vehicle. Both ends of the slits 4k and 4l in the extension direction do not reach both ends in the front-rear direction of the foamed particle molded body 2, and are formed inside the both ends. Furthermore, it is formed inside the annular reinforcing member 3 embedded in the foamed particle molded body 2. That is, both ends in the extension direction of the slits 4k and 4l are formed at positions inward of the front frame portion 31 and the rear frame portion 32, respectively. Inside the annular reinforcing member 3, the slits 4 k 4 l are formed along the lateral sides (that is, the side frame portions 33) extending in the front-rear direction of the reinforcing member 3.

  Further, due to the contraction of the foamed particle molded body 2, the central portion of the side frame portion 33 is pulled inward by the foamed particle molded body 2, and the reinforcing member 3 is distorted. As a result, the composite molded body 10 is easily warped. Become. As illustrated in FIG. 11D, when the slits 4k and 4l extending in the front-rear direction are formed laterally, the influence of the contraction force of the foam particle molded body 2 on the side frame portion 33 can be alleviated. Thereby, generation | occurrence | production of the curvature of the seat cushion core material 1 for vehicles can be suppressed more.

  FIG. 11E shows an example of two slits 4m and 4n extending in the front-rear direction and the vehicle width direction and intersecting each other. The slits 4m are formed from the front to the rear of the foamed particle molded body 2 similarly to the slits shown in FIGS. 9A and 10A, and divide the foamed particle molded body 2. That is, the slit 4m is formed from the front end to the rear end of the foamed particle molded body 2. The slits 4 n are formed to extend in the vehicle width direction of the foamed particle molded body 2. Both ends of the slit 4 n reach both lateral ends of the foamed particle molded body 2 to divide the foamed particle molded body 2. The slits 4 n are formed rearward in the front-rear direction. The slit 4m and the slit 4n cross each other.

  As illustrated in FIG. 11E, when two slits 4 extending in the front-rear direction and in the vehicle width direction and intersecting each other are formed, the contraction force of the foamed particle molded body 2 is transmitted in the front-rear direction and the vehicle width direction. Can be relaxed. Thereby, generation | occurrence | production of the curvature of the seat cushion core material 1 for vehicles can be suppressed more.

  As mentioned above, although an Example was described, this invention is not limited to said each Example, A various change is possible in the range which does not deviate from the summary. For example, the formation pattern of the slits is not limited to those shown in the second and third embodiments, and various modifications are possible. Further, as shown in the first and second embodiments, the composite foam having the foamed particle compact and the reinforcing member embedded therein is particularly suitable for a seat cushion core material for a vehicle, for example, a seat back, It can also be used for exterior members for vehicles, interior members for vehicles, and the like.

1 vehicle seat cushion core 10 composite molded body 2 synthetic resin foamed particle molded body 3 reinforcing member 4 slit

Claims (8)

A composite molded body comprising a synthetic resin foamed particle molded body and a reinforcing member embedded by insert molding in the molded body,
The synthetic resin constituting the above synthetic resin foamed particle molded body is a composite resin obtained by impregnating and polymerizing a styrene-based monomer with a polyolefin-based resin,
A composite molded body, wherein the composite resin comprises a component derived from the styrene-based monomer in a ratio of 250 to 500 parts by mass with respect to 100 parts by mass of the component derived from the polyolefin-based resin.   The composite resin according to claim 1, wherein the component derived from the styrene-based monomer is contained in a ratio of 250 parts by mass or more and less than 350 parts by mass with respect to 100 parts by mass of the component derived from the polyolefin-based resin. Composite molded body.   The composite molded article according to claim 1, wherein the polyolefin resin comprises linear low density polyethylene.   The seat cushion core material for vehicles which consists of a compounding object given in any 1 paragraph of Claims 1-3.   The vehicle seat cushion core material according to claim 4, wherein the reinforcing member is an annular wire frame member, and the annular wire frame member is embedded in the peripheral edge portion of the synthetic resin foam particle molded body.   Furthermore, the seat cushion core material for vehicles of Claim 5 which has a slit formed in order to relieve the unequal shrinkage | contraction of the said synthetic resin foam particle molded object. A method for producing a composite molded body comprising a synthetic resin foamed particle molded body and a reinforcing member embedded in the molded body,
A foaming step of obtaining synthetic resin foamed particles by foaming synthetic resin particles having as a base resin a composite resin formed by impregnating and polymerizing a styrene-based monomer with a polyolefin-based resin;
Insert molding in which the synthetic resin foam particles are fused to one another by heating the synthetic resin foam particles in a mold in which the reinforcing member is disposed, to obtain the composite molded body,
A composite molded article, wherein the composite resin of the synthetic resin particles contains a component derived from the styrene-based monomer in a ratio of 250 to 500 parts by mass with respect to 100 parts by mass of the component derived from the polyolefin-based resin Production method.   The composite resin according to claim 7, wherein the composite resin of the synthetic resin particles has a morphology in which both a component derived from the polyolefin resin and a component obtained by polymerizing the styrene monomer are used as a continuous phase. Method of manufacturing a composite molded body.