JP2021134302A - Styrenic resin foam-molded material, expandable styrenic resin particle, pre-expanded styrenic resin particle and production method for expandable styrenic resin particle - Google Patents

Abstract

To provide a styrenic resin foam-molded material high in fusion rate, excellent in mechanical strength and moldability, hardly generating bubble membrane breakage even if foaming and molding are performed in a high-magnification rate, and superior in appearance glossiness such as whiteness, gloss or the like, also to provide expandable styrenic resin particles and pre-expanded styrenic resin particles used for molding the above resin foam-molded material, and further to provide a production method for such expandable styrenic resin particles.SOLUTION: A styrenic resin foam-molded material in the embodiment of this invention is produced by molding an expandable styrenic resin particle. The expandable styrenic resin particle having a weight average molecular weight of 190,000 to 490,000 includes a polystyrene resin and a foaming agent, and is coated by at least one selected from silicones including aliphatic compounds which are liquids at 5°C and phenyl groups in the amount of 0.01-0.3 mass% based on 100 mass% of the expandable styrenic resin particle.SELECTED DRAWING: None

Description

The present invention relates to a method for producing a styrene-based resin foam molded product, a foamable styrene-based resin particle, a pre-foamed styrene-based resin particle, and a foamable styrene-based resin particle.

Since the foam molded product is lightweight and has excellent heat insulating properties and mechanical strength, it is a heat insulating material used for houses and automobiles, a heat insulating material used for building materials, etc., a packing material for transportation such as fish boxes and food containers, and a cushioning material. Widely used for lumber. Among them, in-mold foam molded products manufactured from foamable particles as a raw material are often used because of their advantages such as easy acquisition of a desired shape.

As for the appearance of the foam molded product, high whiteness is often required for the purpose of use thereof, and it is preferable that the foamed molded product is glossy and beautiful.

In general, a surface additive is used on the surface of the effervescent polystyrene-based resin particles as a raw material of the foam molded product in order to promote the fusion thereof (Patent Documents 1 and 2). However, in conventional surface additives, the surface is often excessively plasticized by heat during foaming and molding. Therefore, when foaming and molding at a high magnification, the bubble film is easily torn, and there is a problem that the foaming ratio must be lowered, the whiteness is lowered, and the gloss is impaired.

On the other hand, if the addition of the surface additive to the surface of the foamable polystyrene-based resin particles as a raw material is reduced in order to suppress the decrease in whiteness and gloss, it becomes difficult to fuse in the foamed molded product. , There is a problem that mechanical strength and moldability are lowered.

Japanese Patent No. 6223097 Japanese Unexamined Patent Publication No. 2014-70150

The present invention has been made to solve the above-mentioned conventional problems, and its main purpose is to have a high fusion rate, excellent mechanical strength and moldability, and even if foaming and molding are performed at a high magnification. It is an object of the present invention to provide a styrene-based resin foam molded article, which is less likely to cause bubble film breakage and has excellent appearance beauty such as whiteness and gloss. Another object of the present invention is to provide foamable styrene-based resin particles and pre-foamed styrene-based resin particles that can be used for molding such a styrene-based resin foam molded product. Further, it is an object of the present invention to provide a method for producing such effervescent styrene resin particles.

The styrene resin foam molded article according to the embodiment of the present invention
A styrene resin foam molded product molded from foamable styrene resin particles.
The effervescent styrene resin particles have a weight average molecular weight of 190,000 to 490,000.
The effervescent styrene resin particles contain a polystyrene resin and a foaming agent.
The foamable styrene resin particles are 0.01% by mass with respect to 100% by mass of the foamable styrene resin particles by at least one selected from an aliphatic compound that is liquid at 5 ° C. and a silicone containing a phenyl group. It is coated in an amount of ~ 0.3% by mass.

In one embodiment, the styrene resin foam molded product has a whiteness of 90 to 99.

The foamable styrene resin particles according to the embodiment of the present invention
Foamable styrene resin particles containing a polystyrene resin and a foaming agent.
The weight average molecular weight is 190,000 to 490,000,
By at least one selected from an aliphatic compound that is liquid at 5 ° C. and a silicone containing a phenyl group, in an amount of 0.01% by mass to 0.3% by mass with respect to 100% by mass of the foamable styrene resin particles. It is covered.

The prefoamed styrene resin particles according to the embodiment of the present invention
Pre-foamed styrene-based resin particles obtained by pre-foaming the above-mentioned foamable styrene-based resin particles.
The average cell diameter of the surface layer is 0.04 mm to 0.15 mm.

The method for producing the foamable styrene resin particles according to the embodiment of the present invention is as follows.
A method for producing the above-mentioned foamable styrene resin particles.
The process of polymerizing styrene-based monomers and
The step of impregnating the foaming agent at the same time as or after the polymerization,
A step of adding at least one selected from an aliphatic compound that is liquid at 5 ° C. and a silicone containing a phenyl group, and
including.

According to the embodiment of the present invention, the fusion rate is high, the mechanical strength and moldability are excellent, the bubble film is less likely to break even if foaming and molding are performed at a high magnification, and the appearance such as whiteness and gloss is obtained. It is possible to provide a styrene-based resin foam molded article having excellent beauty. Further, it is possible to provide foamable styrene-based resin particles and pre-foamed styrene-based resin particles that can be used for molding such a styrene-based resin foamed molded product. Furthermore, it is possible to provide a method for producing such effervescent styrene resin particles.

Hereinafter, embodiments of the present invention will be described, but the present invention is not limited to these embodiments.

As used herein, the term "(meth) acrylic" means acrylic and / or methacryl, and the term "(meth) acrylate" means acrylate and / or methacrylate.

A. Styrene-based resin foamed molded product The styrene-based resin foamed molded product according to the embodiment of the present invention is a styrene-based resin foamed molded product molded from foamable styrene-based resin particles. One preferred embodiment is a styrene-based resin foamed molded product formed from pre-foamed styrene-based resin particles obtained by pre-foaming foamable styrene-based resin particles.

The styrene-based resin foam molded product contains foamed styrene-based resin particles (hereinafter, may be simply referred to as “foamed particles”) obtained by further foaming pre-foamed styrene-based resin particles.

The styrene resin foam molded product is typically composed of a plurality of foamed particles fused to each other.

The styrene resin foam molded product according to the embodiment of the present invention is excellent in appearance beauty such as whiteness and luster.

The whiteness of the styrene resin foam molded product is preferably 90 to 99, more preferably 92 to 99, further preferably 94 to 99, particularly preferably 95 to 99, and most preferably 96. ~ 99. If the whiteness of the styrene resin foam molded product is within the above range, the appearance is excellent and it can be used in many applications.

The styrene-based resin foam molded product can be typically produced by charging pre-foamed styrene-based resin particles into a mold having a predetermined shape according to a purpose and performing in-mold foam molding. More specifically, in-mold foam molding involves (i) filling a closed mold having a large number of small pores with pre-foamed styrene-based resin particles, and (ii) preserving with a heat medium (for example, pressurized steam). Includes: heat-foaming the expanded styrene-based resin particles to obtain foamed particles, (iii) filling the voids between the foamed particles by the heat-foaming, and integrating the foamed particles by fusing them to each other. .. The density of the styrene resin foam molded product can be appropriately set according to the purpose. The density of the styrene-based resin foam molded product is determined by, for example, adjusting the bulk foaming ratio of the pre-foamed styrene-based resin particles to be filled in the mold in advance, or the amount of the pre-foamed styrene-based resin particles filled in the mold. It can be adjusted by adjusting.

The temperature of heat foaming (substantially the temperature of the heat medium) is preferably 90 ° C. to 150 ° C., more preferably 110 ° C. to 130 ° C. The heating foaming time is preferably 5 seconds to 50 seconds, more preferably 10 seconds to 50 seconds. The molding vapor pressure of heat foaming (heat medium blowing gauge pressure) is preferably 0.04 MPa to 0.1 MPa, more preferably 0.06 MPa to 0.08 MPa. If the heat foaming is such a condition, the foamed particles can be satisfactorily fused to each other.

If necessary, the pre-foamed styrene-based resin particles may be aged before molding the styrene-based resin foamed molded product. The aging temperature of the prefoamed styrene resin particles is preferably 20 ° C. to 60 ° C. If the aging temperature is too low, an excessively long aging time may be required. If the aging temperature is too high, the foaming agent in the prefoamed styrene resin particles may dissipate and the moldability may decrease.

The bulk foaming ratio of the foamed particles in the styrene resin foamed molded product is preferably 3 to 100 times, more preferably 30 to 90 times, still more preferably 50 to 80 times, and particularly preferably. It is more than 50 times and 75 times or less, and particularly preferably 55 times to 70 times.

B. Foamable Styrene Resin Particles The foamable styrene resin particles forming the styrene resin foamed molded product according to the embodiment of the present invention have a weight average molecular weight of 190,000 to 490,000 and include a polystyrene resin and a foaming agent. An amount of 0.01% by mass to 0.3% by mass with respect to 100% by mass of the foamable styrene resin particles, depending on at least one selected from an aliphatic compound that is liquid at 5 ° C. and a silicone containing a phenyl group. It is covered with. Such specific effervescent styrene resin particles are effervescent styrene resin particles according to the embodiment of the present invention.

The foamable styrene resin particles have the shape of particles as a whole. The average particle size of the foamable styrene resin particles is preferably 0.3 mm to 3.0 mm, more preferably 0.3 mm to 1.7 mm. The average particle size can be measured according to JIS Z 8815. Specifically, the average particle size is a value measured as a particle size of 50% of the integrated value from the particle size distribution by the sieving test of JIS Z 8815. As the shape of the foamable styrene resin particles, any appropriate shape can be adopted as long as the effects of the present invention are not impaired. Specific examples of such a shape include a spherical shape, a substantially spherical shape, an elliptical spherical shape (egg-shaped), a columnar shape, and a substantially cylindrical shape.

The effervescent styrene resin particles have a weight average molecular weight of 190,000 to 490,000. The weight average molecular weight of the effervescent styrene resin particles is preferably 200,000 to 480,000, more preferably 200,000 to 470,000, still more preferably 200,000 to 460,000, and particularly preferably 200,000 to 200,000. It is 450,000. If the weight average molecular weight of the effervescent styrene resin particles is within the above range, the fusion rate is high, the mechanical strength and moldability are excellent, and even if foaming and molding are performed at a high magnification, bubble film breakage occurs. It is possible to provide a styrene-based resin foam molded product that is difficult to handle and has excellent appearance beauty such as whiteness and luster.

The effervescent styrene resin particles are contained in an amount of 0.01% by mass to 100% by mass based on 100% by mass of the effervescent styrene resin particles by at least one selected from an aliphatic compound that is liquid at 5 ° C. and a silicone containing a phenyl group. It is coated in an amount of 0.3% by mass. The coating amount of at least one selected from the aliphatic compound and the silicone containing a phenyl group is preferably 0.01% by mass to 0.25% by mass with respect to 100% by mass of the foamable styrene resin particles. It is more preferably 0.01% by mass to 0.2% by mass, further preferably 0.01% by mass to 0.15% by mass, and particularly preferably 0.01% by mass to 0.1% by mass. .. If the coating amount of at least one selected from the above aliphatic compounds and silicones containing a phenyl group is within the above range, the fusion rate is high, the mechanical strength and moldability are excellent, and foaming and molding can be performed at a high magnification. It is possible to provide a styrene-based resin foamed molded product which is less likely to break the bubble film even if it is carried out and has excellent appearance beauty such as whiteness and luster. In particular, it is possible to provide a styrene resin foam molded article having excellent gloss.

At least one selected from the aliphatic compounds and silicones containing phenyl groups that are liquid at 5 ° C. is any suitable aliphatic compounds and phenyl groups that are liquid at 5 ° C., as long as the effects of the present invention are not impaired. At least one selected from silicones containing the above can be adopted. The aliphatic compound which is liquid at 5 ° C. may be only one kind or two or more kinds. The phenyl group-containing silicone which is liquid at 5 ° C. may be only one kind or two or more kinds.

Aliphatic compounds that are liquid at 5 ° C. include, for example.
(I) Triglyceride, diglyceride, monoglyceride of fatty acid and glycerin containing fatty acid having 6 to 18 carbon atoms as a main component;
(Ii) Fat oils such as palm oil, palm oil, olive oil, flaxseed oil, sesame oil, fish oil and castor oil;
(Iii) Unsaturated fatty acids such as linoleic acid and linolenic acid;
(Iv) A dicarboxylic acid ester such as diisobutyl adipate;
(V) Liquid paraffin;
(Vi) Acetylated monoglyceride such as glycerin diacet monolaurate;
And so on.

The aliphatic hydrocarbon groups of the fatty acid containing a fatty acid having 6 to 18 carbon atoms as a main component, the triglyceride of glycerin, and the fatty acid constituting the diglyceride may be of the same type, or at least two of them are different. It may be.

Specific examples of the triglyceride, diglyceride, and monoglyceride of the fatty acid and glycerin containing the fatty acid having 6 to 18 carbon atoms as the main component in (i) include, for example, caprylic acid triglyceride, capric acid triglyceride, capric acid, and capric acid. Examples thereof include triglycerides of fatty acids and glycerin, 2-ethylhexyl triglyceride, and fatty acid glycerides of glycerin diacetomonolaurate.

Examples of the phenyl group-containing silicone that is liquid at 5 ° C. include methylphenyl silicone.

The "liquid" in at least one selected from the aliphatic compound which is liquid at 5 ° C. and the silicone containing a phenyl group means the concept of "liquid" which can be usually recognized by those skilled in the art. More specifically, for example, as described in the 5th edition of the Iwanami Physics and Chemistry Dictionary (Iwanami Shoten, 8th edition published on December 20, 2004), it is one of the three states (gas, liquid, solid) of matter. The volume compression ratio is about the same as that of a solid, and it is difficult to compress, but the rigidity is zero, there is no static resistance to displacement stress, it behaves as a fluid, and it has a viscous force according to the gradient of the flow, but For mechanical changes that are fast enough, liquids also behave like solids.

The effervescent styrene resin particles are coated with the above coating amount by at least one selected from an aliphatic compound that is liquid at 5 ° C. and a silicone containing a phenyl group, so that the fusion rate is high and the mechanical strength is high. It is possible to provide a styrene-based resin foamed molded product which is excellent in moldability, is less likely to cause bubble film breakage even if foaming and molding are performed at a high magnification, and is excellent in appearance beauty such as whiteness and gloss.

The effervescent styrene resin particles are used in combination with at least one selected from an aliphatic compound that is liquid at 5 ° C. and a silicone containing a phenyl group, and an antiblocking agent (for example, zinc stearate, magnesium stearate, etc.). Powdered metal soap; Inorganic powder such as silica and calcium carbonate; Silicone without phenyl group such as polydimethylsiloxane; etc.) and antistatic agents (for example, polyethylene glycol, N-hydroxyethyl-N-2-hydroxyalkyl) It may be coated with amine, glycerin, propylene glycol, stearic acid monoglyceride, etc.).

The foamable styrene resin particles include a polystyrene resin and a foaming agent.

B-1. Polystyrene-based resin Polystyrene-based resin is a polymer compound containing a styrene-based monomer as a monomer component constituting the polystyrene-based resin. Styrene-based monomers include styrene or styrene derivatives. Examples of the styrene derivative include α-methylstyrene, vinyltoluene, chlorostyrene, ethylstyrene, i-propylstyrene, dimethylstyrene, bromostyrene and the like. The styrene-based monomer may be only one kind or two or more kinds. The styrene-based monomer preferably contains at least styrene. The content ratio of styrene to the total amount of the styrene-based monomer is preferably 50% by mass or more, more preferably 70% by mass or more, further preferably 90% by mass or more, and particularly preferably 95% by mass or more. Is.

The polystyrene-based resin may contain a styrene-based monomer as a main component of the monomer component constituting the polystyrene-based resin, and may be a copolymer of the styrene-based monomer and the copolymerization component. good. A typical example of the copolymerization component is a vinyl monomer. In the present specification, the "main component" means that the content ratio of the component in all the components is preferably 50% by mass or more, more preferably 70% by mass or more, and further preferably 90% by mass or more. , Particularly preferably 95% by mass or more.

Examples of the vinyl monomer include a polyfunctional monomer, a (meth) acrylic acid ester monomer, a maleic acid ester monomer, and a fumaric acid ester monomer. The vinyl monomer may be only one kind or two or more kinds.

Specific examples of the polyfunctional monomer include divinylbenzene such as o-divinylbenzene, m-divinylbenzene, and p-divinylbenzene; and alkylene such as ethylene glycol di (meth) acrylate and polyethylene glycol di (meth) acrylate. Glycoldi (meth) acrylate; and the like. By using the polyfunctional monomer, a branched structure can be imparted to the polystyrene-based resin. The content of the polyfunctional monomer in all the monomer components constituting the polystyrene-based resin is preferably 0% by mass to 0.1% by mass, and more preferably 0.005% by mass to 0.05% by mass. %.

Specific examples of the (meth) acrylic acid ester monomer include methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, and (meth) acrylic acid. Examples thereof include pentyl, 2-ethylhexyl (meth) acrylate, and hexyl (meth) acrylate. Among these (meth) acrylate monomers, butyl acrylate, 2-ethylhexyl acrylate, and ethyl acrylate are preferable, and butyl acrylate is more preferable. By using the (meth) acrylic acid ester monomer, the glass transition temperature (Tg) of the styrene resin can be lowered. The content of the acrylic acid ester monomer in all the monomer components constituting the polystyrene resin is preferably 0% by mass to 4.0% by mass, and more preferably 0.1% by mass to 3.0%. It is mass%.

Examples of the maleic acid ester monomer include dimethyl maleate.

Examples of the fumaric acid ester monomer include dimethyl fumarate, diethyl fumarate, ethyl fumarate and the like.

In one embodiment, the polystyrene-based resin may be a composite resin of a polystyrene-based resin and a polyolefin-based resin. The content ratio of the polystyrene-based resin to the polyolefin-based resin (polystyrene-based resin / polyolefin-based resin: mass ratio) in the composite resin is preferably 50/50 to 90/10, more preferably 60/40 to 85/15. Is. If the content of the polystyrene resin is too small, the foamability and / or molding processability may be insufficient. If the content of polystyrene resin is too high, impact resistance and / or flexibility may be insufficient.

As the polyolefin-based resin, any suitable olefin-based resin can be adopted as long as the effects of the present invention are not impaired. The polyolefin-based resin may be only one type or two or more types. Specific examples include, for example, branched low-density polyethylene, linear low-density polyethylene, medium-density polyethylene, high-density polyethylene, ethylene-vinyl acetate copolymer, ethylene-methyl methacrylate copolymer, and crosslinked products of these polymers. Polyethylene resins such as propylene homopolymers, propylene-vinyl acetate copolymers, ethylene-propylene random copolymers, propylene-1-butene copolymers, ethylene-propylene-butene random copolymers and other polypropylene resins. ; And so on. Among these polyolefin-based resins, ethylene-vinyl acetate copolymer, high-density polyethylene, linear low-density polyethylene, and mixtures thereof are preferable. The low density is preferably 0.91 g / cm ^{3 to} 0.94 g / cm ³ , and more preferably 0.91 g / cm ^{3 to} 0.93 g / cm ³ . High density is preferably ^{0.95g / cm 3 ~0.97g / cm 3} , more preferably ^{0.95g / cm 3 ~0.96g / cm 3} . Medium density is the density between low density and high density.

B-2. Foaming agent The foaming agent may be only one kind or two or more kinds.

As the foaming agent, any suitable foaming agent can be used as long as the effects of the present invention are not impaired. The foaming agent is preferably an organic compound having a boiling point equal to or lower than the softening point of the styrene resin and is gaseous or liquid at normal pressure. Specific examples thereof include aliphatic hydrocarbons such as propane, n-butane, isopentane, pentane (n-pentane, isopentane or neopentane) and n-hexane; alicyclic hydrocarbons such as cyclopentane and cyclopentadiene; acetone. , Ketones such as methyl ethyl ketone; alcohols such as methanol, ethanol and isopropyl alcohol; low boiling ether compounds such as dimethyl ether, diethyl ether, dipropyl ether and methyl ethyl ether; halogen-containing trichloromonofluoromethane, dichlorodifluoromethane and the like Hydrocarbons; etc. Inorganic gas such as carbon dioxide, nitrogen and ammonia may be used as the foaming agent. Among these, an aliphatic hydrocarbon is preferable as the foaming agent. This is because the destruction of the ozone layer can be prevented, and since the foam is quickly replaced with air, the change over time of the foamed molded product can be suppressed. The foaming agent is more preferably propane, n-butane, isobutane, n-pentane, isopentane, or a combination thereof.

The content of the foaming agent in the foamable styrene-based resin particles can be appropriately set according to the purpose as long as it is an amount sufficient to form the pre-foamed styrene-based resin particles and the styrene-based resin foamed molded product. The content of the foaming agent is preferably 2 parts by mass to 16 parts by mass, and more preferably 3 parts by mass to 8 parts by mass with respect to 100 parts by mass of the polystyrene-based resin.

B-3. Other foamable styrene resin particles may contain a foaming aid as well as a foaming agent. Examples of the foaming aid include diisobutyl adipate, toluene, cyclohexane, ethylbenzene, liquid paraffin, coconut oil and the like. The foaming aid may be only one kind or two or more kinds.

The effervescent styrene resin particles may further contain additives. Examples of the additive include a radiant heat transfer inhibitor, a resin other than a styrene resin, a cross-linking agent, a plasticizer, a filler, a flame retardant, a flame retardant aid, a lubricant, a colorant, an antistatic agent, and a spreading agent. Examples include bubble conditioners, weather resistant agents, antistatic agents, antifogging agents, and fragrances. The type, number, combination, content, etc. of additives can be appropriately set according to the purpose. The additive may be only one kind or two or more kinds.

B-4. Method for Producing Foamable Styrene Resin Particles One embodiment of the method for producing foamable styrene resin particles includes a step of polymerizing a styrene-based monomer and a step of impregnating a foaming agent at the same time as or after the polymerization. It comprises the step of adding at least one selected from an aliphatic compound that is liquid at 5 ° C. and a silicone containing a phenyl group.

As a typical method for polymerizing a styrene-based monomer, a suspension polymerization method can be mentioned. In the suspension polymerization method, a polymerization initiator is dissolved in a styrene-based monomer, the temperature is raised in a reaction vessel together with water in which the suspension agent is dispersed, polymerization is carried out, and then the particles are cooled to obtain effervescent styrene-based resin particles. How to get it.

The method of adding the foaming agent during and / or after the completion of the polymerization is called a one-step method. The particles obtained by polymerization without adding a foaming agent are screened, and only the particles in the required particle size range are heated in water in which the suspending agent in the reaction vessel is dispersed, and the foaming agent is added here. The method of impregnating the particles is called a two-step method (post-impregnation method). In addition, small styrene resin particles (seed particles) are put into a reaction vessel containing water in which a suspending agent is dispersed, the temperature is raised, and then the monomer in which the polymerization initiator is dissolved is continuously added. The method of supplying the particles to the reaction vessel, polymerizing them, and growing them to the desired particle size is called a seed polymerization method. In the seed polymerization method, the foaming agent is added during and / or after the completion of the polymerization. Foamable styrene resin particles can be produced by any of the one-step method, the two-step method (post-impregnation method), and the seed polymerization method. Further, either method has an advantage that spherical foamable styrene resin particles can be obtained.

As the polymerization initiator in the polymerization of the styrene-based monomer, any appropriate radical-generating polymerization initiator can be used as long as the effects of the present invention are not impaired. Examples of such a polymerization initiator include benzoyl peroxide, t-butylperoxy-2-ethylhexanoate, t-butylperoxybenzotoate, t-butylperoxy-2-ethylhexyl monocarbonate, and dicumyl. Peroxide, t-butylperoxypivalate, t-butylperoxyisopropyl carbonate, 2,2-t-butylperoxybutane, t-butylperoxy-3,3,5-trimethylhexanoate, di-t -Organic peroxides such as butylperoxyhexaihydroterephthalate; azo compounds such as azobisdimethylvaleronitrile; and the like. These polymerization initiators may be only one kind or two or more kinds.

The polymerization initiator includes a polymerization initiator having a decomposition temperature in the range of 50 to 80 ° C. for obtaining a half-life of 10 hours in order to adjust the molecular weight and reduce the amount of residual monomer, and a polymerization initiator of 10 hours. A polymerization initiator having a decomposition temperature in the range of 80 to 120 ° C. for obtaining a half-life may be used in combination. Since the polymerization initiator needs to be uniformly absorbed by the seed particles, it is preferable to add the polymerization initiator as a liquid substance. When the polymerization initiator is added directly into the aqueous suspension, it becomes difficult for the seed particles to be uniformly absorbed. Therefore, the polymerization initiator is added in a suspended or emulsified state in an aqueous medium, or a small amount of styrene-based simple substance is added. It is desirable to dissolve in the emulsion, add an inorganic suspension stabilizer and / or an anionic surfactant, and add as an aqueous suspension.

As a step of adding at least one selected from an aliphatic compound and a silicone containing a phenyl group which is liquid at 5 ° C., typically, at least one selected from an aliphatic compound and a silicone containing a phenyl group is added. It is applied to the surface of the foamable styrene resin particles obtained by the above polymerization. As a method of adding at least one selected from the aliphatic compound which is liquid at 5 ° C. and the silicone containing a phenyl group, for example, the foamable styrene resin particles obtained by the above polymerization, the aliphatic compound and the phenyl group are added. A method of mixing at least one selected from silicone containing silicone using a mixer such as a tumbler, a ribbon blender, a Nauter mixer, or a stirrer can be mentioned.

In another embodiment of the method for producing foamable styrene resin particles, the foamable styrene resin particles can be produced by a melt extrusion method. In the melt extrusion method, polystyrene resin pellets are supplied to the resin supply device, a foaming agent is press-fitted and kneaded into the polystyrene resin melted in the resin supply device, and the molten resin containing the foaming agent is applied to the tip of the resin supply device. This is a method of extruding from the small holes of the attached die and then cooling to obtain foamable styrene resin particles. The method of extruding directly into the cooling liquid from the small holes of the die, cutting the extruded product with a rotary blade immediately after extruding, and cooling the cut particles in the cooling liquid is called a hot cut method. Strand cutting is a method of extruding the strands into the air from the small holes of the die once, guiding them into the cooling water tank before the strands foam, cooling the strands in the cooling water tank, and then cutting them into columnar particles. It is called the method (cold cut method). Foamable styrene resin particles can be produced by either a hot-cut method or a strand-cut method (cold-cut method). According to the hot-cut method, there is an advantage that substantially spherical foamable styrene resin particles can be obtained.

C. Pre-foamed styrene-based resin particles One preferred embodiment of the styrene-based resin foamed molded product is a styrene-based resin foamed molded product formed from pre-foamed styrene-based resin particles obtained by pre-foaming foamable styrene-based resin particles. be.

The surface layer of the prefoamed styrene resin particles has an average cell diameter of 0.04 mm to 0.15 mm, preferably 0.04 mm to 0.14 mm, more preferably 0.04 mm to 0.13 mm, and particularly. It is preferably 0.04 mm to 0.12 mm, and most preferably 0.04 mm to 0.11 mm. If the average cell diameter of the surface layer of the prefoamed styrene resin particles is within the above range, the fusion rate is high, the mechanical strength and moldability are excellent, and the bubble film breaks even if foaming and molding are performed at a high magnification. It is possible to provide a styrene-based resin foamed molded product that is less likely to occur and has excellent appearance beauty such as whiteness and gloss, and in particular, can provide a styrene-based resin foamed molded product having excellent whiteness.

That is, the pre-foamed styrene-based resin particles according to the embodiment of the present invention are obtained by pre-foaming the foamable styrene-based resin particles according to the above item B. Pre-foaming includes foaming the effervescent styrene resin particles to a desired bulk foaming ratio (bulk density) using steam or the like. The bulk foaming ratio of the prefoamed styrene resin particles is preferably 3 to 100 times, more preferably 30 to 90 times, and further preferably 50 to 70 times. The bulk density is the reciprocal of the bulk foaming ratio. The bulk foaming ratio and bulk density can be obtained, for example, as follows.

W (g) of effervescent styrene resin particles is collected as a measurement sample. This measurement sample is naturally dropped into a graduated cylinder, and the volume V (cm ³ ) of the measurement sample dropped into the graduated cylinder is measured using an apparent density measuring device compliant with JIS K 6911. From the mass and volume of the measurement data, the bulk foaming multiple and bulk density can be obtained based on the following formula.
Bulk foaming multiple (times = cm ³ / g) = volume of measurement sample (V) / mass of measurement sample (W)
Bulk density (g / cm ³ ) = mass of measurement sample (W) / volume of measurement sample (V)

In one typical embodiment, the prefoamed styrene resin particles can be used for molding a styrene resin foamed molded product. In another embodiment, the prefoamed styrene resin particles can be used as they are as a buffer, a heat insulating material, or the like. When the pre-foamed styrene-based resin particles are used as they are, the pre-foamed styrene-based resin particles can preferably be used as a filler in which a large number of pre-foamed styrene-based resin particles are filled in a bag.

Hereinafter, the present invention will be specifically described with reference to Examples, but the present invention is not limited to these Examples. The measurement method and evaluation method for each characteristic are as follows.

<Weight average molecular weight of effervescent styrene resin particles>
The weight average molecular weight means a polystyrene (PS) -equivalent average molecular weight measured by gel permeation chromatography (GPC). Specifically, 3 mg of the sample was added to 10 mL of tetrahydrofuran (THF) and allowed to stand for 72 hours to dissolve (completely dissolved), and the obtained solution was used as a non-aqueous 0.45 μm chromatodisk (13N) manufactured by Kurabo Industries Ltd. ) Was filtered and measured. The average molecular weight of the sample was determined from the calibration curve of standard polystyrene prepared by measuring in advance. The conditions of the chromatograph are as follows.
(Measurement condition)
Equipment used: High-speed GPC equipment, manufactured by Tosoh, HLC-8320GPC EcoSEC system (built-in RI detector)
Guard column: Tosoh, TSKguardcolum SuperHZ-H (4.6 mm ID x 2 cmL) x 1 Column: Tosoh, TSKgel SuperHZM-H (4.6 mm ID x 15 cmL) x 2 Column temperature: 40 ° C.
System temperature: 40 ° C
Mobile phase: Tetrahydrofuran Mobile phase Flow rate: Sample side = 0.175 mL / min, Reference side = 0.175 mL / min Detector: RI detector, sample concentration = 0.3 g / L
Injection volume: 50 μL
Measurement time: 0 to 25 minutes Runtime: 25 minutes Sampling pitch: 200 msec
(Creation of calibration curve)
As a standard polystyrene sample for a calibration curve, the weight average molecular weight of the trade name "TSK standard POLYSTYRENE" manufactured by Tosoh Corporation is 5,480,000, 3,840,000, 355,000, 102,000, 37,900, Standard polystyrene samples of 9,100, 2,630,500 and those having a weight average molecular weight of 1.03 million under the trade name "Shodex STANDARD" manufactured by Showa Denko KK were used.
The method of creating the calibration curve is as follows. The standard polystyrene sample for the calibration curve is group A (with a weight average molecular weight of 1.03 million) and group B (with a weight average molecular weight of 3,840,000, 102,000, 9,100,500). , And Group C (those with a weight average molecular weight of 5,480,000, 355,000, 37,900, 2,630). After weighing 5 mg of group A, it was dissolved in 20 mL of tetrahydrofuran (solution A), group B was also weighed 5 mg to 10 mg each, then dissolved in 50 mL of tetrahydrofuran (solution B), and group C was also weighed 1 mg to 5 mg, respectively. Dissolved in 40 mL of tetrahydrofuran (C solution). For the standard polystyrene calibration curve, 50 μL of each of the prepared A solution, B solution, and C solution is injected, and the calibration curve (third-order formula) is obtained from the retention time obtained after the measurement. It was obtained by preparing with (EcoSEC-WS) and measured using the calibration curve.

<Average cell diameter on the surface of the prefoamed styrene resin particles>
The average cell size was measured according to the test method of ASTM D2842-69. Specifically, from among the pre-foamed styrene-based resin particles foamed at a bulk foaming multiple of 60 times, 10 arbitrarily selected particles are formed on a plane passing near the center of the pre-foamed styrene-based resin particles using a shaving blade. Divide it into two equal parts, and use a scanning electron microscope (manufactured by JOEL, trade name "JSM-6360LV") to divide one of the cut surfaces into two equal parts. The outside was magnified 100 times and photographed.
Next, the photographed image is printed on A4 paper, a straight line with a length of 60 mm is drawn at an arbitrary position, and the average chord length (t) of the bubbles is calculated from the number of bubbles existing on this straight line by the following formula. bottom.
Average string length t (μm) = 60 / (number of bubbles x magnification of photo)
When drawing a straight line, the straight line was made to penetrate as much as possible without making point contact with the bubbles. In addition, when some bubbles come into point contact with each other in a straight line, these bubbles are included in the number of bubbles, and when both ends of the straight line do not penetrate the bubbles and are located inside the bubbles. Also included in the number of bubbles the bubbles where both ends of the straight line are located. Then, the bubble diameter was calculated by the following formula based on the calculated average chord length t.
Average cell diameter (μm) D = t / 0.616
Further, the bubble diameter was calculated at any three points of the captured image in the same manner as described above, and the arithmetic mean value of the bubble diameters for a total of five images was taken as the average bubble diameter of the prefoamed styrene resin particles.

<Measurement of whiteness of styrene resin foam molded product>
The whiteness of the styrene resin foam molded product was measured by the following method. The whiteness was evaluated by color difference measurement based on JIS Z8729-2004 "Color Display Method-L * a * b * Color System". For the measurement, a color difference meter (manufactured by Konica Minolta, model: CR-400) and a standard white plate calibration plate (Y: 94.3, x: 0.3144, y: 0.3208) are used for standard matching. board. Using a calibrated color difference meter, measurements were taken at 20 arbitrary points on the surface of the flat plate-shaped styrene resin foam molded product, and the average value of the lightness L * values was defined as whiteness.
The evaluation was as follows.
93 and above: ◎
90-92: 〇 Less than 90: ×

<Measurement of glossiness of styrene resin foam molded product>
The styrene resin foam molded product obtained in Examples and Comparative Examples was allowed to stand in a constant temperature room set at 24 ° C. for 24 hours. Next, using a gloss meter (Gloss Checker IG-331 manufactured by HORIBA, Ltd.), a 60 ° meter (incident angle 60 °, light receiving angle) was used for any 20 points on the surface of the flat plate-shaped styrene resin foam molded body. The glossiness was measured at 60 °), and the average value was taken as the glossiness.
The evaluation was as follows.
27 or above: ◎
24-26: 〇 Less than 24: ×

<Evaluation of fusion rate of styrene resin foam molded product>
After making a cut line with a depth of about 2 mm with a cutter knife along a straight line connecting the centers of a pair of long sides on the surface of a flat plate-shaped styrene resin foam molded body having a width of 300 mm, a length of 400 mm, and a thickness of 30 mm. The styrene-based resin foam molded product is manually divided into two along the cut line, and the number of particles broken in the particles in an arbitrary range of 100 to 150 with respect to the foamed particles in the fracture surface (a). ) And the number of particles (b) broken at the interface between the particles, and the value obtained by substituting into the equation [(a) / ((a) ten (b))] × 100 is fused. The rate (%) was used.
The evaluation of the cohesiveness was as follows.
90% or more: ◎
80% or more and less than 90%: 〇 Less than 80%: ×

<Comprehensive evaluation>
The three items of whiteness, glossiness, and fusion rate were evaluated under the following conditions.
If all three items are ◎: ◎
If there is no x in 3 items and there is 1 or more ○: 〇 If even one of 3 items has x: ×

[Example 1]
<Manufacturing of foamable styrene resin particles>
To a polymerization vessel with a stirrer having a content of 100 liters, 40,000 parts by mass of water, 100 parts by mass of tricalcium phosphate as a suspension stabilizer, and 3.2 parts by mass of sodium dodecylbenzenesulfonate as an anionic surfactant were supplied and stirred. Then, 40,000 parts by mass of styrene, 102 parts by mass of benzoyl peroxide as a polymerization initiator, and 24 parts by mass of t-butylperoxy-2-ethylhexyl monocarbonate were added, and the temperature was raised to 90 ° C. for polymerization. Then, the temperature was maintained at this temperature for 6 hours, and the temperature was further raised to 125 ° C. and then cooled 2 hours later to obtain styrene resin particles. The obtained styrene-based resin particles were sieved to obtain styrene-based resin particles having a particle diameter of 0.5 mm to 0.71 mm (average particle diameter of 0.63 mm) as seed particles. The rotation speed of stirring was adjusted so that the above particle size could be obtained.
Next, 2150 parts by mass of seed particles, 30 parts by mass of magnesium pyrophosphate, and 1.0 part by mass of sodium dodecylbenzenesulfonate were supplied to a polymerization vessel with an internal volume of 25 liters and heated to 72 ° C. with stirring. Then, a dispersion liquid was prepared. Subsequently, a solution prepared by dissolving 31 parts by mass of benzoyl peroxide and 4 parts by mass of t-butylperoxy-2-ethylhexyl monocarbonate in a monomer mixture of 786 parts by mass of styrene and 137 parts by mass of butyl acrylate was added. , Was supplied into the above dispersion while stirring. Then, after the above solution was completely supplied into the dispersion liquid, it was maintained at 72 ° C. for 60 minutes.
Next, 2346 parts by mass of styrene was constantly supplied while raising the temperature to 87 ° C. in 1 hour, and then 2.2 parts by mass of divinylbenzene was dissolved in 3744 parts by mass of styrene while holding at 87 ° C. for 1 hour and 30 minutes. The monomer mixture was fed constantly and held for an additional 30 minutes.
Then, the temperature was raised to 125 ° C. and held for 30 minutes to react the unreacted monomers. Then, the mixture was cooled to 100 ° C., 92 parts by mass of cyclohexane, 82 parts by mass of diisobutyl adipate, and 640 parts by mass of mixed butane were press-fitted into the polymerization vessel and held for 2 hours, and then the inside of the polymerization vessel was cooled to 25 ° C. Then, effervescent particles (weight average molecular weight: 380,000) were obtained. 0.03 parts by mass of polyethylene glycol, 0.13 parts by mass of zinc stearate, fatty acid triglyceride (85% of fatty acid having 8 carbon atoms (caprylic acid), fatty acid having 10 carbon atoms (10 parts by mass) with respect to 100 parts by mass of the obtained effervescent particles. Caprylic acid) A triglyceride of fatty acid and glycerin having a fatty acid composition of 15%. It is a liquid at 5 ° C.) 0.03 parts by mass was applied to obtain effervescent styrene resin particles (1).
The obtained effervescent styrene resin particles (1) were left in a constant temperature room at 13 ° C. for 5 days. Then, the foamable styrene-based resin particles (1) were heated ^{and pre-foamed to a bulk density of 0.0166 g / cm 3} to obtain pre-foamed styrene-based resin particles (1).
The obtained prefoamed styrene resin particles (1) were aged at 20 ° C. for 24 hours, and then left to stand for 24 hours in a room temperature atmosphere, followed by in-mold foam molding. An ACE-3SP molding machine manufactured by Sekisui Koki Co., Ltd. was used for in-mold foam molding, and foam molding was performed into a flat plate shape having a width of 300 mm, a length of 400 mm, and a thickness of 30 mm. The heating time was 8 seconds for one side, 2 seconds for one side, 5 seconds for both sides, and the molding pressure (steam blowing gauge pressure) was 0.06 MPa. As a result, a styrene resin foam molded product (1) was obtained.
The results are shown in Table 1.

[Example 2]
The effervescent styrene resin particles (2), in the same manner as in Example 1 except that the weight average molecular weight of the effervescent styrene resin particles was adjusted to 300,000 by changing the amount of divinylbenzene to 1.1 parts by mass. Preliminary foamed styrene-based resin particles (2) and styrene-based resin foamed molded product (2) were obtained.
The results are shown in Table 1.

[Example 3]
Foamable styrene-based resin particles (3), pre-foamed styrene-based resin particles (3), styrene-based resin foam molding in the same manner as in Example 1 except that the amount of medium-chain fatty acid triglyceride was changed to 0.01 parts by mass. Body (3) was obtained.
The results are shown in Table 1.

[Example 4]
Foamable styrene resin particles (4), prefoamed styrene resin particles (4), styrene resin foam molding in the same manner as in Example 1 except that the amount of medium-chain fatty acid triglyceride was changed to 0.1 parts by mass. Body (4) was obtained.
The results are shown in Table 1.

[Example 5]
Foamable styrene resin particles (5), prefoamed styrene resin particles (5), styrene resin foam molding in the same manner as in Example 1 except that the amount of medium chain fatty acid triglyceride was changed to 0.3 parts by mass. Body (5) was obtained.
The results are shown in Table 1.

[Example 6]
Styrene-based resin particles (6), pre-foamed styrene-based resin particles (6), styrene-based resin in the same manner as in Example 1 except that the medium-chain fatty acid triglyceride was changed to diisobutyl adipate (liquid at 5 ° C.). A foam molded product (6) was obtained.
The results are shown in Table 1.

[Example 7]
Foamable styrene-based resin particles (7), pre-foamed styrene-based resin particles (7), styrene-based resin foaming in the same manner as in Example 1 except that the medium-chain fatty acid triglyceride was changed to liquid paraffin (liquid at 5 ° C.). A molded body (7) was obtained.
The results are shown in Table 1.

[Example 8]
Foamable styrene resin particles (8), prefoamed styrene resin particles (8), styrene resin in the same manner as in Example 1 except that the medium chain fatty acid triglyceride was changed to methylphenyl silicone (liquid at 5 ° C). A foam molded product (8) was obtained.
The results are shown in Table 1.

[Example 9]
The effervescent styrene resin particles (9), in the same manner as in Example 1 except that the weight average molecular weight of the effervescent styrene resin particles was adjusted to 200,000 by changing the amount of divinylbenzene to 0.3 parts by mass. Preliminary foamed styrene-based resin particles (9) and styrene-based resin foamed molded product (9) were obtained.
The results are shown in Table 1.

[Example 10]
Examples except that the weight average molecular weight of the effervescent styrene-based resin particles was adjusted to 450,000 by changing the amount of divinylbenzene to 2.8 parts by mass and the amount of medium-chain fatty acid triglyceride was changed to 0.1 parts by mass. In the same manner as in 1, foamable styrene resin particles (10), preliminary foamed styrene resin particles (10), and styrene resin foam molded product (10) were obtained.
The results are shown in Table 1.

[Comparative Example 1]
Foamable styrene resin particles (C1), prefoamed styrene resin particles (C1), styrene resin foam molding in the same manner as in Example 1 except that the amount of medium chain fatty acid triglyceride was changed to 0.4% by mass. Body (C1) was obtained.
The results are shown in Table 1.

[Comparative Example 2]
Foamable styrene resin particles (C2), prefoamed styrene resin particles (C2), and styrene resin foamed molded product (C2) were obtained in the same manner as in Example 1 except that the medium chain fatty acid triglyceride was not added. rice field.
The results are shown in Table 1.

[Comparative Example 3]
Effervescent styrene resin particles (C3), preliminary expanded styrene resin particles (C3), styrene resin in the same manner as in Example 1 except that the medium chain fatty acid triglyceride was changed to stearic acid triglyceride (solid at 5 ° C.). A foam molded product (C3) was obtained.
The results are shown in Table 1.

[Comparative Example 4]
The effervescent styrene resin particles (C4) and pre-foaming were carried out in the same manner as in Example 1 except that the weight average molecular weight of the effervescent styrene resin particles was adjusted to 180,000 by changing the amount of divinylbenzene to 0 parts by mass. Styrene-based resin particles (C4) and styrene-based resin foam molded product (C4) were obtained.
The results are shown in Table 1.

[Comparative Example 5]
The effervescent styrene resin particles (C5), in the same manner as in Example 1 except that the weight average molecular weight of the effervescent styrene resin particles was adjusted to 500,000 by changing the amount of divinylbenzene to 3.1 parts by mass. Preliminary foamed styrene-based resin particles (C5) and styrene-based resin foamed molded product (C5) were obtained.
The results are shown in Table 1.

As is clear from Table 1, according to the examples of the present invention, the fusion rate is high, the mechanical strength and moldability are excellent, and even if foaming and molding are performed at a high magnification, bubble film breakage occurs. It is possible to provide a styrene-based resin foam molded product that is difficult to use and has excellent appearance such as whiteness and luster. Further, it is possible to provide foamable styrene-based resin particles and pre-foamed styrene-based resin particles that can be used for molding such a styrene-based resin foamed molded product. Furthermore, it is possible to provide a method for producing such effervescent styrene resin particles.

The foamable styrene resin particles, the preliminary foamed styrene resin particles, and the styrene resin foam molded product according to the embodiment of the present invention are heat insulating materials used for houses and automobiles, heat insulating materials used for building materials, fish boxes, and foods. It is suitably used as a packaging material for transportation such as containers, a cushioning material, and the like. More specifically, the foamable styrene resin particles, the pre-foamed styrene resin particles, and the styrene resin foam molded product are used as a wall heat insulating material, a floor heat insulating material, a roof heat insulating material, an automobile heat insulating material, and a hot water tank. It is preferably used as a heat insulating material for plastics, a heat insulating material for piping, a heat insulating material for a solar system, a heat insulating material for a water heater, a container for foods and industrial products, a packing material for fish and agricultural products, a filling material, a core material for tatami mats, and the like.

Claims (5)

A styrene resin foam molded product molded from foamable styrene resin particles.
The effervescent styrene resin particles have a weight average molecular weight of 190,000 to 490,000.
The effervescent styrene resin particles contain a polystyrene resin and a foaming agent.
The foamable styrene resin particles are 0.01% by mass with respect to 100% by mass of the foamable styrene resin particles by at least one selected from an aliphatic compound that is liquid at 5 ° C. and a silicone containing a phenyl group. Covered with an amount of ~ 0.3% by weight,
Styrene resin foam molded product. The styrene resin foam molded product according to claim 1, wherein the whiteness is 90 to 99. Foamable styrene resin particles containing a polystyrene resin and a foaming agent.
The weight average molecular weight is 190,000 to 490,000,
By at least one selected from an aliphatic compound that is liquid at 5 ° C. and a silicone containing a phenyl group, in an amount of 0.01% by mass to 0.3% by mass with respect to 100% by mass of the foamable styrene resin particles. Covered,
Effervescent styrene resin particles. Pre-expanded styrene-based resin particles obtained by pre-foaming the effervescent styrene-based resin particles according to claim 3.
The average cell diameter of the surface layer is 0.04 mm to 0.15 mm.
Preliminary expanded styrene resin particles. The method for producing foamable styrene resin particles according to claim 3.
The process of polymerizing styrene-based monomers and
The step of impregnating the foaming agent at the same time as or after the polymerization,
A step of adding at least one selected from an aliphatic compound that is liquid at 5 ° C. and a silicone containing a phenyl group, and
including,
A method for producing foamable styrene resin particles.