JP6619713B2 - Expandable styrene resin particles, expanded styrene resin particles and filler - Google Patents

Description

  The present invention provides a foamed styrene resin particle having excellent recoverability against compressive stress, a filler filled with the foamed styrene resin particle in a bag, and usable as a cushioning material or a heat insulating material, and the foamed styrene resin particle. The present invention relates to expandable styrenic resin particles for producing, and a method for producing them.

  Foam molded articles made of styrene-based resins have excellent buffering properties and heat insulation properties, and are easy to mold. Therefore, they are often used as packaging materials and heat insulation materials. In particular, a styrene-based foam molded article molded from foamed resin particles called the bead method is easy to obtain a desired shape, has very low productivity of mill ends, and has excellent characteristics.

  In recent years, an example in which the foamed resin particles are filled in a bag-shaped packing material and used as a cushioning material is increasing, and since the shape is relatively free, it is used as a cushioning material (cushion body or the like). However, as it is used, the initial shape cannot be maintained due to compressive stress or the like, and there is a possibility that the buffering property is lowered.

  As a technique for increasing the elasticity of a foamed resin molded body, a foamed molded body using high impact polystyrene (hereinafter abbreviated as HIPS) in which an elastic body such as butadiene rubber is blended with a polystyrene resin has been proposed.

  Patent Document 1 discloses a method for producing a polystyrene resin foam molded article using a block copolymer of styrene and butadiene as an elastic body. Patent Document 2 discloses a foamed molded article made of a polystyrene-based resin having a predetermined amount of butadiene as an elastic body and having a softening temperature of 100 ° C. or higher. Patent Document 3 discloses a foamed molded body made of a polystyrene resin in which non-oriented rubber particles are blended as an elastic body.

  However, both of the foamed resin molded body blended with the conventional elastic body disclosed in Patent Documents 1 to 3 and the foamed resin particle before molding have a problem that recovery from deformation is insufficient.

  When a block copolymer of styrene and butadiene is used, the copolymer is expensive, which is industrially disadvantageous. When non-oriented rubber particles are used, the rubber particles are deformed. It is difficult to retain the foaming agent due to the difficulty of foaming, and further, until the bubbles inside the pre-foamed particles become uniform as in the foamable polymer composition disclosed in Patent Document 3. There is also a problem that the aging period becomes long.

  On the other hand, Patent Document 4 discloses expandable polystyrene resin particles including a resin dispersion portion made of a polystyrene resin in which polyacrylic acid ester fine particles are dispersed and a surface layer portion made of a polystyrene resin surrounding the resin dispersion portion.

  In Patent Document 5, 7.0 to 80.0 parts by weight of a styrene monomer and an acrylate ester are added to 100 parts by weight of polystyrene resin seed particles in a dispersion obtained by dispersing polystyrene resin seed particles. A first polymerization step of supplying 2.0 to 12.0 parts by mass of a monomer and absorbing and polymerizing these monomers into seed particles to grow polystyrene resin seed particles; A method for producing expandable polystyrene resin particles is disclosed, which includes a second polymerization step in which only a monomer is supplied for polymerization and a step in which a foaming agent is impregnated.

  Patent Document 6 discloses expanded styrene resin particles in which a carbon material is added to improve heat insulation.

Japanese Patent Publication No. 47-17465 Japanese Patent Publication No.47-18428 JP-A-56-67344 JP2011-68817A WO2009 / 096327 Japanese Patent Laid-Open No. 2006-121324

  In Patent Document 4, expandable polystyrene resin particles including a resin dispersion part made of a polystyrene resin in which polyacrylic acid ester fine particles are dispersed and a surface layer part made of a polystyrene resin surrounding the resin dispersion part are pre-foamed. The foam molded body obtained by foam molding is described as having a high degree of fusion between the pre-foamed particles and being excellent in impact resistance. However, the foamed particles obtained by pre-expanding the expandable polystyrene-based resin particles are insufficiently recovered from deformation from the study by the present inventors, and the foamed particles are filled into a bag body as a cushioning material or a heat insulating material. It was found unsuitable for use.

  In Patent Document 5, the foamable particles obtained by the above-described method described in the document can be used to form a foamed resin molded body using a low pressure of water vapor, and the molding time can be shortened. It is believed that there is no improvement in recovery from deformation.

  When using a filler filled with foamed resin particles in a bag as a heat insulating material, the heat insulating material is installed in the building for a long period of time, so it becomes impossible to maintain the initial shape due to compressive stress due to its own weight during use. There is a problem that decreases.

  Accordingly, the present invention provides a foamed styrene resin particle having an excellent recovery rate against compressive stress, a filling material in which the foamed styrene resin particle is filled in a bag, and can be used as a buffer material or a heat insulating material, and the foamed styrene resin. An object of the present invention is to provide expandable styrenic resin particles for producing particles, and a method for producing them.

The present invention firstly
Expandable styrene resin particles containing a styrene resin and a foaming agent,
An acrylic ester polymer, a copolymer of an acrylic ester monomer and a styrene monomer, or the acrylic ester polymer dispersed throughout the expandable styrene resin particles. The present invention relates to an expandable styrenic resin particle characterized by containing fine particles of a mixture with the copolymer.

  The foamable styrene resin particles of the present invention can be foamed to form foamed styrene resin particles having excellent recoverability against compressive stress.

The present invention secondly,
Expanded styrene resin particles containing styrene resin in which bubbles are formed,
In the whole of the expanded styrene resin particles, in the bubble film of the styrene resin surrounding the bubbles, an acrylic ester polymer, a copolymer of an acrylic ester monomer and a styrene monomer, Alternatively, the present invention relates to expanded styrene resin particles, characterized in that fine particles of a mixture of the acrylate ester polymer and the copolymer are present.

  The expanded styrenic resin particles of the present invention have a high recovery force against compressive stress, and can maintain the initial shape, buffering property or heat insulating property over a long period of time.

Third, the present invention
A bag,
The present invention relates to a filler comprising the above-mentioned expanded styrene resin particles of the present invention filled in the bag.

  As described above, the expanded styrene resin particles of the present invention are not easily deformed by compressive stress, and the initial shape, buffering property or heat insulating property can be maintained over a long period of time. The body is unlikely to undergo deformation during use, reduced buffering, or reduced thermal insulation. The filler of the present invention is particularly useful as a cushioning material or a heat insulating material.

Fourth, the present invention
In a dispersion obtained by dispersing styrene resin seed particles in water, an acrylate monomer or a monomer mixture of an acrylate monomer and a styrene monomer is supplied, A monomer or monomer mixture is polymerized in the seed particles, and in the seed particles, an acrylic ester polymer, a copolymer of an acrylic ester monomer and a styrene monomer, Or, forming a microparticle of a mixture of the acrylate ester polymer and the copolymer to form a microparticle-containing styrene resin particle,
Without performing the step of further growing the fine particle-containing styrene resin particles by polymerization after the fine particle formation step, or in the middle of the fine particle formation step, a foaming agent is added to the fine particle-containing styrene resin particles. The present invention relates to a method for producing expandable styrenic resin particles including an impregnation step.

  According to this aspect of the present invention, it is possible to easily produce expandable styrene resin particles that can be formed by foaming expanded styrene resin particles having excellent recoverability against compressive stress.

Fifth, the present invention
The present invention relates to an expandable styrene resin particle produced by the method for producing an expandable styrene resin particle of the present invention.

  The expandable styrenic resin particles of this aspect of the present invention can be expanded to form expanded styrene resin particles having excellent recoverability against compressive stress.

Sixth, the present invention
A method for producing foamed styrene resin particles, comprising a foaming step of foaming the foamable styrene resin particles produced by the method for producing foamable styrene resin particles of the present invention to form foamed styrene resin particles. About.

  According to this aspect of the present invention, it is possible to easily produce expanded styrene resin particles having excellent recoverability against compressive stress.

Seventh, the present invention
The present invention relates to a foamed styrene resin particle produced by the method for producing a foamed styrene resin particle of the present invention.

  The expanded styrene resin particles of this aspect of the present invention are excellent in recoverability against compressive stress.

Eighth, the present invention
The present invention relates to a method for producing a filler, including a filling step of filling a bag with the foamed styrene resin particles produced by the method for producing foamed styrene resin particles of the present invention.

  According to this aspect of the present invention, it is possible to easily produce a filler that is less likely to undergo deformation during use, a decrease in buffering properties, or a decrease in heat insulating properties.

  According to the present invention, the expanded styrene resin particles having excellent recoverability against compressive stress, the filler filled with the expanded styrene resin particles in a bag, and usable as a cushioning material or a heat insulating material, the expanded styrene system Expandable styrenic resin particles for producing resin particles and a method for producing them are provided.

FIG. 1 a is an observation image obtained by photographing the central part of the cross section of the expandable styrene resin particles produced in Example 1 at a magnification of 20,000 times. FIG. 1 b is an observation image obtained by photographing the central part of the cross section of the expandable styrene resin particles produced in Example 1 at a magnification of 5,000 times. FIG. 1 c is an observation image obtained by photographing the surface layer portion of the cross section of the expandable styrenic resin particles produced in Example 1 at a magnification of 5,000 times. Drawing 2 is a mimetic diagram of the section of one embodiment of the filling object of the present invention.

<1. Material>
In the present invention, the styrene resin includes styrene or a styrene derivative alone or a copolymer. Here, examples of the styrene derivative include α-methylstyrene, vinyltoluene, chlorostyrene, ethylstyrene, i-propylstyrene, dimethylstyrene, and bromostyrene. In the present invention, the styrene or styrene derivative in the form of a monomer is referred to as a styrene monomer. Further, the styrene resin may be a copolymer using a vinyl monomer copolymerizable with the styrene monomer, as long as the styrene monomer component is a main component. Examples of the vinyl monomer include divinylbenzene such as o-divinylbenzene, m-divinylbenzene, and p-divinylbenzene, and alkylene glycol di (meth) such as ethylene glycol di (meth) acrylate and polyethylene glycol di (meth) acrylate. Polyfunctional monomers such as acrylates; α-methylstyrene, (meth) acrylonitrile, methyl (meth) acrylates and the like are mentioned, polyfunctional monomers are preferred, ethylene glycol di (meth) acrylate, and n is a polyethylene having 4 to 16 Glycol di (meth) acrylate, divinyl base More preferably Zen, divinylbenzene, ethylene glycol di (meth) acrylate are particularly preferred. The monomer copolymerizable with styrene may be used alone or in combination. The “styrene resin” can also be called “polystyrene resin”.

  The styrenic resin seed particles used as a starting material in the fine particle forming step of the production method of the expandable styrene resin particles (hereinafter sometimes referred to as “expandable resin particles”) of the present invention includes the styrene resin as a main component. Particles which may contain other components. A part of or all of the seed particles may be a styrene resin recovered product. Furthermore, the particle diameter of the seed particles can be appropriately adjusted according to the average particle diameter of the foamable resin particles to be produced. For example, it is preferable to use seed particles having an average particle diameter of about 0.2 to 0.4 mm. The average particle size of the seed particles was a value measured in accordance with JISZ8815 as a particle size with an integrated value of 50% from a particle size distribution according to a sieving test described in JISZ8815. The weight average molecular weight of the styrenic resin forming the seed particles is not particularly limited, but is preferably 150,000 to 700,000, more preferably 200,000 to 500,000.

  In the present invention, an acrylate polymer is a polymer containing one or more acrylate monomers as constituent monomers. Examples of the acrylate monomer include methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, pentyl acrylate, 2-ethylhexyl acrylate, hexyl acrylate, etc. Among these, butyl acrylate, 2-ethylhexyl acrylate and ethyl acrylate are preferred, and butyl acrylate is particularly preferred.

  In the present invention, the copolymer of an acrylate monomer and a styrene monomer comprises a single monomer comprising one or more acrylate monomers and one or more styrene monomers. It is a copolymer contained as a monomer. Each monomer can be selected from the above range. In the copolymer, the ratio of the acrylate monomer to the styrene monomer is not particularly limited, but the styrene resin particles are not compatible with the styrene resin and exist as dispersed fine particles. In order to do this, the styrene monomer is preferably less than 50 parts by weight, more preferably 30 parts by weight or less, more preferably 20 parts by weight or less, with respect to 100 parts by weight of the acrylate monomer. Is preferred.

  In the present invention, an acrylic ester polymer and a mixture of a copolymer of an acrylic ester monomer and a styrene monomer refer to a mixture of the polymer and the copolymer. The mixing ratio is not particularly limited.

  In the present invention, acrylic ester polymer microparticles, acrylic ester monomer and styrene monomer copolymer microparticles, and the mixture microparticles are average particles, respectively. The diameter is preferably in the range of 1 to 500 nm, more preferably 10 to 400 nm, and most preferably 150 to 250 nm. When the average particle diameter of the fine particles is 1 nm or more, the foamed styrene resin particles of the present invention are preferably provided with sufficient impact resistance and recovery from compression. It is preferable that the average particle size of the fine particles is 500 nm or less because the rate of dissipation of the foaming agent from the expandable resin particles of the present invention is sufficiently small.

  In the present invention, the average particle size of the fine particles contained in the expandable resin particles and the expanded styrene resin particles refers to the average particle size measured by the following measurement method. Moreover, the said microparticle should just be a particle | grain containing the said polymer, the said copolymer, or the said mixture, and the structure which includes a styrene resin inside may be sufficient.

<Average particle size of fine particles inside resin particles>
The expandable styrene resin particles and the expanded styrene resin particles (hereinafter referred to as “resin particles”) are embedded in an epoxy resin, the resin particles are cut, and ruthenium tetroxide dyeing is performed on the cross section. Then, the stained surface is made into an ultrathin section and photographed with a transmission electron microscope manufactured by Hitachi, Ltd. The major axis and minor axis of the fine particles are measured, and the average value of the major axis and minor axis is taken as the particle diameter per minute particle. This operation was performed for 30 arbitrary microparticles, and the total average particle size of the microparticles was calculated as the average particle size of the microparticles.

<2. Expandable styrenic resin particles and process for producing the same>
The expandable styrene resin particles of the present invention are
An acrylic ester polymer, a copolymer of an acrylic ester monomer and a styrene monomer, which contains a styrene resin and a foaming agent and is dispersed throughout the expandable styrene resin particles. It contains fine particles of a blend or a mixture of the acrylate polymer and the copolymer.

  The expandable resin particles of the present invention are excellent in resilience against compression and buffering properties when the foamed styrene-based resin particles described later are foamed by the presence of the fine particles dispersed throughout. Expanded styrene resin particles capable of maintaining heat insulation properties can be formed. In FIG. 1a, FIG. 1b and FIG. 1c, the expandable resin particles produced in Example 1 are embedded in an epoxy resin, cut to pass through the center of the expandable resin particles, and ruthenium tetroxide dyeing on the cross section. An observation image obtained by taking a photograph with a transmission electron microscope and making the stained surface an ultrathin section is shown. FIG. 1a is a photograph of the central part of the particle cross section at 20,000 times, FIG. 1b is a photograph of the central part of the particle cross section at 5,000 times, and FIG. It is. In the study of the present inventor, as shown in Comparative Example 3, the foamed resin particles obtained by foaming the foamable resin particles in which the fine particles are dispersed in the central part but not in the surface layer part are: It has been confirmed that resiliency to compression is not sufficient.

  Here, the fine particles are “dispersed throughout the expandable styrene resin particles” as long as the fine particles are dispersed throughout the expandable resin particles. There is no need to disperse the resin particles at a uniform density at a uniform density, and the density may be uneven. More preferably, the resin particles are dispersed at a substantially uniform density without a large unevenness in density. The fact that the fine particles are “dispersed throughout the expandable styrene resin particles” means, for example, on the cross section of the expandable resin particles that has the largest area, the entire cross section More specifically, the fine particles are dispersed. More specifically, when the maximum width of the cross section is D, in the cross section, a circle having a diameter of 0.1D is included in the cross section. In any of the positions, one or more fine particles are present in the circle, and more preferably, the diameter of the circle is 0.05D. More preferably, the density of the microparticles in a spherical portion having a diameter of 0.1D at an arbitrary position enclosed in the expandable resin particles is X, and the density of the entire microparticles of the expandable resin particles is Y. Sometimes X is 0.5Y to 1.5Y, more preferably 0.7Y to 1.3Y, and still more preferably 0.9Y to 1.1Y. Here, the density of the fine particles in the entire expandable resin particles is the ratio of the weight of the fine particles to the total amount of components other than the foaming agent in the entire expandable resin particles, specifically, It refers to the content of fine particles described in the following paragraphs. Similarly, the density of the microparticles in the part is the ratio of the weight of the microparticles contained in the part to the total amount of components other than the foaming agent in the part. More preferably, the diameter of the sphere of the part is 0.05D.

  In the expandable resin particles of the present invention, the content of the fine particles is not particularly limited, but is, for example, 1 to 40% by weight with respect to the total amount of components other than the foaming agent of the expandable resin particles, and more Preferably, it is 5 to 30% by weight. The acrylate polymer and / or the copolymer of the acrylate monomer and the styrene monomer constituting the fine particles has an affinity for a foaming agent containing a hydrocarbon, and is a styrene resin. Therefore, if the content of the microparticles is too large, the holding power of the foaming agent is reduced. However, the foamability of the present invention can be reduced by setting the content of the microparticles to 40% by weight or less or 30% by weight or less. It is possible to sufficiently retain the foaming agent of the resin particles. Moreover, sufficient compression recovery force is realizable by content of the said microparticle with respect to the whole quantity of components other than a foaming agent of the said expandable resin particle being 1 weight% or more or 5 weight% or more.

  The whole amount of the expandable resin particles of the present invention or the total amount of components other than the foaming agent of the spherical portion was heated for 30 minutes by placing the expandable resin particles of the present invention or the spherical portion in a 150 ° C. pyrolysis furnace. It can be measured later by determining the total amount of residue.

  The foaming agent contained in the foamable resin particles in the present invention is not particularly limited as long as it is conventionally used for foaming of styrene-based resins. For example, carbon such as isobutane, n-butane, isopentane, and neopentane. Examples include volatile foaming agents (physical foaming agents) such as aliphatic hydrocarbons having a number of 5 or less, and butane is preferred.

  The content of the foaming agent in the foamable resin particles may be an amount sufficient for the formation of the foamed resin particles, for example, with respect to the total amount of components other than the foaming agent of the foamable resin particles (as described above). 3 to 13% by weight.

  The content of the foaming agent in the expandable resin particles is determined by placing the expandable styrene resin particles in a pyrolysis furnace at 150 ° C. and measuring the amount of hydrocarbon generated in the pyrolysis furnace with a chromatograph. Can do.

  The foamable resin particles can contain a foaming aid together with a foaming agent. As the foaming aid, any foaming aid conventionally used for foamable resin particles can be used without particular limitation. For example, aromatic organic compounds such as styrene, toluene, ethylbenzene, xylene, cyclohexane, etc. And a solvent having a boiling point of 200 ° C. or less under one atmospheric pressure, such as cycloaliphatic hydrocarbons such as methylcyclohexane, ethyl acetate, and butyl acetate.

  Furthermore, in the foamable resin particles, a plasticizer having a boiling point of more than 200 ° C. at one atmospheric pressure, for example, a phthalate ester, is used in order to maintain good foam moldability even when the pressure of water vapor used during heat foaming is low. Further, glycerin fatty acid esters such as glycerin diacetomonolaurate, glycerin tristearate and glycerin diacetomonostearate, adipic acid esters such as diisobutyl adipate, and plasticizers such as coconut oil may be contained.

  The expandable styrenic resin particles of the present invention include an anti-binding agent, a bubble regulator, a cross-linking agent, a filler, a flame retardant, a flame retardant aid, a lubricant, a colorant and the like within a range that does not impair physical properties. Additives may be added, and if powdered metal soaps such as zinc stearate are applied to the surface of the expandable styrene resin particles, the particles may be bonded to each other in the expansion step of the expandable styrene resin particles. This is preferable because the binding can be reduced.

When the expandable styrenic resin particles of the present invention are used for forming expanded resin particles to be filled in a filler to be described later used as a heat insulating material, the heat insulation is further improved within a range that does not impair the physical properties. It is preferable to include a material such as a carbon material. As the carbon material, the carbon material disclosed in JP-A-2006-121324 can be used. Specifically, carbon black, activated carbon, graphite, graphene, coke, carbon nanofiber, mesoporous carbon, glass Carbon materials such as carbon, hard carbon and soft carbon, preferably conductive carbon black such as acetylene black and ketjen black. The carbon material preferably has a specific surface area of 10 to 3000 m ² / g in order to impart sufficient heat insulation. As for content of a carbon material, 0.5-25 mass parts can be illustrated with respect to 100 mass parts of styrene resin, for example. When content is less than 0.5 mass part, heat insulation may not fully be improved. On the other hand, when the content exceeds 25 parts by mass, the foam film may be broken, so that the moldability may be reduced and the heat insulation may be inferior.

  The particle diameter of the expandable styrene resin particles of the present invention can be selected according to the particle diameter of the expanded styrene resin particles to be produced. For example, the particle diameter of the expandable styrene resin particles of the present invention is in the range of 0.2 to 0.6 mm as the average particle diameter. The average particle size was a value measured as a particle size with an integrated value of 50% from the particle size distribution according to the sieving test described in JISZ8815 in accordance with JISZ8815.

The method for producing the expandable styrene resin particles of the present invention will be described below.
In the method for producing expandable styrene resin particles of the present invention, an acrylic ester monomer or an acrylic ester monomer is dispersed in a dispersion in which the above styrene resin seed particles are dispersed in water. A monomer mixture of styrene monomer and polymerizing the monomer or monomer mixture in the seed particles, and in the seed particles, an acrylate polymer, acrylic acid A microparticle-containing styrene resin particle is formed by forming microparticles of a copolymer of an ester monomer and a styrene monomer, or a mixture of the acrylate ester polymer and the copolymer. A microparticle formation process for generating
Without performing a step of further growing the fine particle-containing styrene resin particles by polymerization after the fine particle formation step, or in the middle of the fine particle formation step, a foaming agent is added to the fine particle-containing styrene resin particles. Impregnation, and an impregnation step.

  In the fine particle forming step, water is put into a reaction vessel such as an autoclave, the seed particles are dispersed in the water, and the monomer or the monomer mixture is continuously or intermittently supplied into the water. And an acrylic ester polymer, a copolymer of an acrylic ester monomer and a styrene monomer, or the acrylic ester on the surface and inside of the seed particles in the presence of a polymerization initiator. Microparticles of a mixture of the system polymer and the copolymer are grown.

  The polymerization initiator that can be used in the fine particle forming step is not particularly limited as long as it is conventionally used for the polymerization of acrylate monomers, and for example, benzoyl Peroxide, t-butyl peroxybenzoate, t-butyl peroxy-2-ethylhexanoate, lauryl peroxide, t-butyl peroxide, t-butyl peroxypivalate, t-butyl peroxyisopropyl carbonate, t Organic peroxides such as butyl peroxyacetate, 2,2-t-butylperoxybutane, t-butylperoxy-3,3,5-trimethylhexanoate, di-t-butylperoxyhexahydroterephthalate, Azobisisobutyronitrile, azobisdimethylvaleronitrile, etc. Azo compounds, and the like. Among these polymerization initiators, those having a decomposition temperature of 80 to 120 ° C. for obtaining a half-life of 10 hours are particularly preferable. One type of this polymerization initiator can be used alone, or two or more different types of polymerization initiators can be used in combination.

  Further, in the fine particle forming step, the suspension stabilizer used for dispersing the seed particles and the droplets of the monomer or monomer mixture in the water includes suspension polymerization of a styrene resin. As long as it is used, it can be used without any particular limitation, for example, water-soluble polymers such as polyvinyl alcohol, methylcellulose, polyacrylamide, and polyvinylpyrrolidone, poorly soluble such as tricalcium phosphate, magnesium pyrophosphate, etc. An inorganic compound etc. are mentioned. One type of suspension stabilizer can be used alone, or two or more types of suspension stabilizers can be used in combination.

  When using a poorly soluble inorganic compound as the suspension stabilizer, it is preferable to use an anionic surfactant in combination. Examples of such anionic surfactants include fatty acid soaps, N-acyl amino acids or salts thereof, carboxylates such as alkyl ether carboxylates, alkylbenzene sulfonates, alkyl naphthalene sulfonates, and dialkyl sulfosuccinates. Sulfonates such as alkyl sulfoacetates and α-olefin sulfonates; sulfates such as higher alcohol sulfates, secondary higher alcohol sulfates, alkyl ether sulfates, polyoxyethylene alkylphenyl ether sulfates, etc. Salt; Phosphoric acid ester salts such as alkyl ether phosphoric acid ester salts and alkyl phosphoric acid ester salts. These anionic surfactants can be used alone or in combination of two or more.

  In the fine particle forming step, the amount of the monomer or monomer mixture supplied to water is, for example, 1 to 67 parts by weight, preferably 5 to 45 parts by weight, with respect to 100 parts by weight of the seed particles. Can do. By making the supply amount of the monomer or monomer mixture within this range, in the foamable resin particles to be produced, the content of the fine particles is, for example, with respect to the total amount of components other than the foaming agent. It can be in the range of 1 to 40% by weight, preferably 5 to 30% by weight.

  In the fine particle forming step, when supplying the monomer mixture, the ratio of the acrylate monomer to the styrene monomer in the monomer mixture is It can be set similarly to the ratio of the acrylate monomer and the styrene monomer in the copolymer with the styrene monomer.

  In the fine particle formation step, the monomer or monomer mixture can be supplied in a plurality of steps, and the monomer or monomer mixture supplied in each step is the same. It may be different or different. For example, when performing the process of supplying only an acrylic ester monomer and the process of supplying a monomer mixture of an acrylic ester monomer and a styrene monomer, a foamable resin produced In the particles, fine particles of a mixture of the acrylate polymer and the copolymer are dispersed throughout.

  In the fine particle forming step, after supplying the monomer or monomer mixture in the dispersion, the seed particles are absorbed, and the reaction conditions for polymerization in the seed particles can be adjusted as appropriate. it can. For example, the reaction temperature is 70 to 120 ° C., and the reaction time is 30 to 300 minutes. This condition is particularly suitable for producing fine particle-containing styrene resin particles in which the fine particles are dispersed and contained throughout the styrene resin seed particles.

  In the impregnation step, the fine particle-containing styrenic resin may be formed without performing a step of further growing the fine particle-containing styrenic resin particles by polymerization after the fine particle formation step or in the middle of the fine particle formation step. In this step, the particles are impregnated with a foaming agent. By starting the impregnation step at this point, the foamable resin particles to be produced are in a state in which the fine particles are dispersed throughout the styrenic resin phase. Expanded styrene resin particles having excellent recoverability against stress can be produced.

  Here, “the step of further growing the fine particle-containing styrenic resin particles by polymerization” means that a styrenic monomer is further added and the styrenic polymer is further added to the surface of the fine particle-containing styrenic resin particles. A step of forming and growing a layer is mentioned. As shown in Comparative Example 3, when performing the “step of further growing the fine particle-containing styrenic resin particles by polymerization”, the present inventors substantially put the fine particles on the surface layer portion of the expandable resin particles. It has been found that foamed styrene resin particles obtained by forming a portion not contained in the foam and foaming it have low recoverability against compressive stress. For this reason, when the said impregnation process is performed after the said microparticle formation process, it is preferable to perform the said impregnation process, without performing the process of growing the said microparticle containing styrene-type resin particle further by superposition | polymerization.

  When the impregnation step is performed in the middle of the fine particle forming step, the foaming agent is impregnated in the fine particle-containing styrenic resin particles during the growth of the fine particles.

  The impregnation step is carried out by supplying a foaming agent to the dispersion in a container for performing the microparticle formation step after or during the completion of the microparticle formation step, particularly from the viewpoint that the operation is simple. preferable.

  In the impregnation step, the temperature when impregnating the foaming agent is preferably 60 ° C. or higher, more preferably 70 ° C. or higher from the viewpoint of promoting impregnation and improving production efficiency, and the fine particle-containing styrenic resin particles From the viewpoint of preventing mutual fusion, it is preferably 120 ° C. or lower, more preferably 100 ° C. or lower.

  In the impregnation step, the fine particle-containing styrenic resin particles can be impregnated with the foaming aid together with the foaming agent. The foaming aid is as described above.

  After completion of the impregnation step, the produced resin particles are taken out and, if necessary, washed and dried to obtain expandable styrene resin particles.

  The surface of the expandable styrene resin particles of the present invention is coated with a surface treatment agent such as a fatty acid metal salt, a fatty acid ester, or an antistatic agent, as is usually done for conventional expandable resin particles. It is possible to improve the fluidity and foaming characteristics of the expandable resin particles (beads) by coating the surface treatment agent.

  The expandable styrenic resin particles of the present invention can contain the above various other components in addition to the foaming agent and the fine particles. These other components may be independently contained in the seed particles, or in the fine particle forming step, in addition to the monomer or monomer mixture, supplied to the dispersion. In the impregnation step, in addition to the foaming agent, it may be supplied into the dispersion and absorbed in the seed particles.

<3. Expanded styrene resin particles and process for producing the same>
The expanded styrene resin particles of the present invention (hereinafter sometimes referred to as “expanded resin particles”)
Containing a styrene resin in which bubbles are formed, and
In the whole of the expanded styrene resin particles, in the bubble film of the styrene resin surrounding the bubbles, an acrylic ester polymer, a copolymer of an acrylic ester monomer and a styrene monomer, Alternatively, microparticles of a mixture of the acrylate polymer and the copolymer are present.

  The foamed resin particles of the present invention have high recoverability against compressive stress, and buffer properties and heat insulation properties are maintained for a long period of time. Especially suitable for.

  In the foamed resin particles, a large number of bubbles dispersed in the continuous phase of the styrene resin are formed, and each bubble is surrounded by a cell membrane of the styrene resin.

  In the foamed resin particles of the present invention, the fine particles are present in the cell membrane. The thickness of the bubble film is generally greater than 500 nm. The fine particles are presumed to give the bubble film resistance to compressive stress, but the mechanism is not particularly limited.

  The foamed resin particles of the present invention are characterized in that the fine particles are present in the cell membrane in the whole foamed resin particles. When the fine particles are present in the foamed film in the whole foamed resin particles, the foamed resin particles of the present invention are excellent in recoverability against compression and can maintain buffering properties and heat insulation properties. Here, “in the whole of the foamed resin particles” means that the microparticles are present in the cell membrane. On the cross section of the foamed resin particles, the microparticles are present in the cell membrane as a whole. The fine particles need not be dispersed at a uniform density in each part of the foamed resin particles, and the density may be biased, but more preferably, the density is not greatly biased. Dispersed with a substantially uniform density. For example, on the cross section of the foamed resin particle that has the largest area, the microparticles are present in a dispersed state throughout the bubble film that appears in the cross section. Where the maximum width of the cross section is E, and a circle with a diameter of 0.1E is included in the cross section in any position in the cross section so as to be included in the cross section. 1 or more of the fine particles are present in the bubble film, and more preferably the diameter of the circle is 0.05E. More preferably, when the density of the microparticles in a spherical portion having a diameter of 0.1E at an arbitrary position enclosed in the foamed resin particles is W, and the density of the microparticles in the entire foamed resin particles is Z. , W is 0.5Z to 1.5Z, more preferably 0.7Z to 1.3Z, and still more preferably 0.9Z to 1.1Z. Here, the density of the fine particles in the whole foamed resin particles is a ratio of the weight of the fine particles to the total weight of the foamed resin particles, specifically, the inclusion of the fine particles described in the following paragraphs. Refers to the quantity. Similarly, the density of the microparticles in the part is the ratio of the weight of the microparticles contained in the part to the total weight of the part. More preferably, the diameter of the sphere of the part is 0.05E.

  In the foamed resin particles of the present invention, the content of the fine particles is not particularly limited, but is, for example, 1 to 40% by weight, more preferably 5 to 30% by weight, based on the total amount of the foamed resin particles. is there. By setting the content of the fine particles to 1% by weight or more or 5% by weight or more with respect to the total amount of the foamed resin particles, a sufficient compression recovery force can be realized.

  The particle diameter of the expanded resin particles of the present invention can be selected according to the intended use of the filler. For example, the particle diameter of the foamed resin particles of the present invention is in the range of 0.4 to 5.0 mm as the average particle diameter. The average particle size was a value measured as a particle size with an integrated value of 50% from the particle size distribution according to the sieving test described in JISZ8815 in accordance with JISZ8815.

  The foamed resin particles of the present invention can be produced by foaming the foamable resin particles obtained by the above production method or the foamable resin particles of the present invention. For this reason, the foamed resin particles of the present invention may further contain the above-mentioned other components as components that the foamable resin particles can contain.

Examples of the method for foaming the expandable resin particles obtained by the above production method include a method of heating the expandable resin particles by steam heating or the like using a well-known apparatus and method in the field of foamed resin molding production. . The foamed resin particles formed by this method have an appropriate bulk density according to the intended use, and are preferably in the range of 0.02 to 0.20 g / cm ³ , for example, 0.02 to More preferably within the range of 0.10 g / cm ³ . The bulk density of the foamed resin particles can be measured, for example, by the following method.

<Bulk density of foamed resin particles>
First, Wg was collected from the foamed resin particles as a measurement sample, and this measurement sample was naturally dropped into a graduated cylinder, and the volume Vcm ³ of the measurement sample dropped into the graduated cylinder was measured using an apparent density measuring instrument based on JIS K6911. The bulk density of the foamed resin particles is measured based on the following formula.
Bulk density (g / cm ³ ) = mass of measurement sample (W) / volume of measurement sample (V)

<4. Filled body>
The present invention also provides
A bag,
The present invention relates to a filler comprising the expanded styrene resin particles of the present invention filled in the bag.

  In FIG. 2, one Embodiment of the filler of this invention is shown. The filling body 10 of the present embodiment includes a bag body 1 and a large number of the expanded styrene resin particles 2 of the present invention filled in the bag body 1.

  As described above, the foamed resin particles of the present invention have a high recovery property against compressive stress, and can maintain the original shape and maintain the buffering property and the heat insulating property over a long period of time. For this reason, the filling body of the present invention filled with the foamed resin particles of the present invention is particularly useful as a buffer material or a heat insulating material.

The cushioning material includes cushions, beds, mattresses, pillows, stuffed animals, toys, cushioning materials for packaging, and the like.
The said heat insulating material includes the heat insulating material for houses installed in the wall part and ceiling part of a house.

  As a bag body, it can comprise with the material etc. which were formed with the raw material which has a stretching property, a chemical fiber, or natural fiber (silk, hemp, cotton, etc.). The material having elasticity is a material having elasticity, and for example, spandex (polyurethane elastic yarn) or the like is preferable.

  The bag can be provided with a zipper that can be opened and closed. The bag may have a double structure. Furthermore, it is also possible to adopt a configuration in which a plurality of the above-mentioned fillers are put in one large bag. In this case, the foamed resin particles in the plurality of bags may have different tactile sensations.

[Examples and Comparative Examples]
<Average particle diameter of polyacrylate microparticles inside resin particles>
The expandable styrene resin particles are embedded in an epoxy resin, the expandable styrene resin particles are cut, and ruthenium tetroxide dyeing is performed on the cross section. Then, the stained surface is made into an ultrathin section and photographed with a transmission electron microscope manufactured by Hitachi, Ltd. The major axis and minor axis of the polyacrylate microparticles are measured and averaged to obtain the particle size per microparticle. This operation was performed on 30 arbitrary polyacrylate microparticles, the total average particle size of the microparticles was calculated, and the average particle size of the polyacrylate microparticles was obtained.

<Compression recovery rate of foamed resin particles>
After foaming to a bulk density of 0.033 g / cm ³ using a pre-foaming apparatus, the mixture is aged at 20 ° C. for 24 hours to obtain foamed styrene resin particles (foamed resin particles). Next, a glass graduated cylinder having a capacity of 2000 cc is filled with the foamed resin particles in a range of 1000 cc ± 10 cc. The initial volume is V0. Next, a plastic disc having a diameter difference of 0.3 mm or less from the inner diameter of the measuring flask is placed on the top surface of the filled foamed resin particles. A load is applied uniformly on the plastic disc in an atmosphere of 25 ° C. and a humidity of 50%, and pressure is applied until the volume of the foamed resin particles reaches 500 cc. After being left under the pressure for 24 hours, the load is removed and the volume V of the expanded resin particles is measured after another 6 hours.

The compression recovery rate of the foamed resin particles is measured from the following calculation formula.
Compression recovery rate (%) = V / V0 × 100
The obtained foamed resin particles were evaluated as 回復 (very good) when the recovery rate was 90% or more, ◯ (good) when 85% or more and less than 90%, and x (bad) when less than 85%.

[Example 1]
A polymerization vessel equipped with a stirrer with an internal capacity of 100 liters is supplied with 40000 parts by mass of water, 100 parts by mass of tricalcium phosphate as a suspension stabilizer, and 2.0 parts by mass of calcium dodecylbenzenesulfonate as an anionic surfactant, while stirring. After adding 40000 parts by mass of a monomer and 96.0 parts by mass of benzoyl peroxide and 28.0 parts by mass of t-butylperoxybenzoate as a polymerization initiator, the temperature was raised to 90 ° C. to polymerize. And it hold | maintained at this temperature for 6 hours, and also it cooled after 2 hours, after heating up to 125 degreeC, and obtained the styrene-type resin particle (a).

  The styrene resin particles (a) were sieved to obtain styrene resin particles (b) having a particle diameter of 0.2 to 0.4 mm as seed particles.

  Next, in a polymerization vessel equipped with a stirrer having an internal volume of 5 liters, 2000 parts by mass of water, 2000 parts by mass of the styrene resin particles (b), 6.0 parts by mass of magnesium pyrophosphate as a suspension stabilizer, and an anionic surfactant As the above, 0.3 parts by mass of calcium dodecylbenzenesulfonate was supplied and heated to 70 ° C. while stirring.

  Next, 2.0 parts by mass of benzoyl peroxide and 1.0 part by mass of t-butylperoxybenzoate as polymerization initiators were dissolved in 200 parts by mass of butyl acrylate (hereinafter referred to as “acrylate sample”). ) Was fed into the 5 liter polymerization vessel and absorbed into the seed particles and held at 70 ° C. for 90 minutes. Next, 126 parts by mass of normal pentane as a blowing agent was injected into the polymerization vessel, and then the temperature was raised to 120 ° C. to complete the reaction. After cooling to 30 ° C. or lower, taking out from the polymerization vessel and drying, it was left in a constant temperature room at 13 ° C. for 5 days to obtain expandable styrene resin particles. The average particle diameter of the fine particles of the butyl acrylate polymer inside the obtained expandable styrene resin particles was 210 nm.

  1a, 1b and 1c, the expandable styrenic resin particles produced in Example 1 are embedded in an epoxy resin, cut so as to pass through the center of the expandable resin particles, and ruthenium tetroxide in the cross section. The observation image obtained by dyeing | staining and making a dyeing | staining surface into an ultra-thin section and taking a photograph with a transmission electron microscope is shown. FIG. 1a is a photograph of the central part of the particle cross section at 20,000 times, FIG. 1b is a photograph of the central part of the particle cross section at 5,000 times, and FIG. 1c is an observation image obtained by photographing the surface layer part of the particle cross section at 5,000 times. It is. It was confirmed that the fine particles of the acrylate polymer were dispersed throughout the expandable styrene resin particles.

(Foam)
Subsequently, zinc stearate and hydroxystearic acid triglyceride were coated as surface treatment agents on the surface of the expandable styrene resin particles.

Next, after foaming to a bulk density of 0.033 g / cm ³ using a pre-foaming apparatus, the mixture was aged at 20 ° C. for 24 hours to obtain foamed styrene resin particles (foamed resin particles).

In addition, 500 g of expandable resin particles were put into a polypropylene container having an internal volume of 1 L and stored at 25 ° C. The passage of time capable of foaming with a bulk density of 0.033 g / cm ³ was defined as foaming agent retention. The foaming agent retention of the foamed resin particles of this example was 50 days and was very good. Furthermore, the compression recovery rate of the foamed resin particles was 93%, which was very good. The overall evaluation was also very good (◎).

(Standard for foam retention)
Very good (（): 50 days or more.
Good (O): 40 days or more and less than 50 days.
Defect (x): Less than 40 days.

(Comprehensive evaluation criteria)
Very good (（): Both foaming agent retention and compression recovery are very good (極 め て).
Good (◯): There is no defect (x) in both the foaming agent retention and the compression recovery rate, and either is good (◯).
Defect (x): There is a defect (x) in either foaming agent retention or compression recovery rate.

[Example 2]
Instead of the acrylate sample of Example 1, a polymerization initiator in which 0.5 parts by mass of benzoyl peroxide and 0.25 parts by mass of t-butyl peroxybenzoate were dissolved in 50 parts by mass of butyl acrylate was used. Except that, foamed resin particles were obtained in the same manner as in Example 1.

[Example 3]
In place of the acrylic ester sample of Example 1, 1.0 parts by mass of benzoyl peroxide and 0.5 parts by mass of t-butyl peroxybenzoate as a polymerization initiator were dissolved in 100 parts by mass of butyl acrylate. Except that, foamed resin particles were obtained in the same manner as in Example 1.

[Example 4]
In place of the acrylic ester sample of Example 1, 7.0 parts by mass of benzoyl peroxide and 3.5 parts by mass of t-butylperoxybenzoate as a polymerization initiator were dissolved in 700 parts by mass of butyl acrylate. Except that, foamed resin particles were obtained in the same manner as in Example 1.

[Example 5]
Instead of the acrylate sample of Example 1, a polymerization initiator prepared by dissolving 10.0 parts by mass of benzoyl peroxide and 5.0 parts by mass of t-butyl peroxybenzoate in 1000 parts by mass of butyl acrylate was used. Except that, foamed resin particles were obtained in the same manner as in Example 1.

[Example 6]
Instead of the acrylate sample of Example 1, 2.2 parts by mass of benzoyl peroxide and 1.1 parts by mass of t-butylperoxybenzoate as polymerization initiators were added to 200 parts by mass of butyl acrylate and 20 parts by mass of styrene. Expanded resin particles were obtained in the same manner as in Example 1 except that the dissolved one was used.

[Example 7]
The following operations were performed using styrene resin particles (b) having a particle diameter of 0.2 to 0.4 mm prepared by the method of Example 1 as seed particles.

  In a polymerization vessel equipped with a stirrer having an internal volume of 5 liters, 2000 parts by mass of water, 2000 parts by mass of the styrene resin particles (b), 6.0 parts by mass of magnesium pyrophosphate as a suspension stabilizer, and dodecylbenzene as an anionic surfactant The temperature was raised to 70 ° C. while supplying 0.3 parts by mass of calcium sulfonate and stirring.

  Next, 0.5 parts by mass of benzoyl peroxide and 0.25 parts by mass of t-butyl peroxybenzoate as a polymerization initiator were dissolved in 50 parts by mass of butyl acrylate and supplied to the 5 liter polymerization vessel. Then, it was absorbed into the seed particles and held at 70 ° C. for 90 minutes.

Further, 1.7 parts by mass of benzoyl peroxide and 0.85 parts by mass of t-butylperoxybenzoate as a polymerization initiator were dissolved in 150 parts by mass of butyl acrylate and 20 parts by mass of styrene in the 5 liter polymerization vessel. After feeding, the seed particles were absorbed and held at 70 ° C. for 90 minutes. Next, 126 parts by mass of normal pentane as a blowing agent was injected into the polymerization vessel, and then the temperature was raised to 120 ° C. to complete the reaction. After cooling to 30 ° C. or lower, it was taken out from the polymerization vessel, dried, and left in a thermostatic chamber at 13 ° C. for 5 days to obtain expandable styrene resin particles. The average particle diameter of the butyl acrylate polymer inside the obtained expandable styrene resin particles was 200 nm. Subsequently, after foaming to a bulk density of 0.033 g / cm ³ using a pre-foaming apparatus, the mixture was aged at 20 ° C. for 24 hours to obtain foamed resin particles as in Example 1.

[Example 8]
Expanded resin particles were obtained in the same manner as in Example 1 except that 2-ethylhexyl acrylate was used instead of butyl acrylate.

[Comparative Example 1]
A polymerization vessel equipped with a stirrer with an internal capacity of 100 liters is supplied with 40000 parts by mass of water, 100 parts by mass of tricalcium phosphate as a suspension stabilizer, and 2.0 parts by mass of calcium dodecylbenzenesulfonate as an anionic surfactant, while stirring. After adding 40000 parts by mass of a monomer and 96.0 parts by mass of benzoyl peroxide and 28.0 parts by mass of t-butylperoxybenzoate as a polymerization initiator, the temperature was raised to 90 ° C. to polymerize. And it hold | maintained at this temperature for 6 hours, and also, after heating up to 125 degreeC, it cooled after 2 hours, and obtained the styrene-type resin particle (a).

  The styrene resin particles (a) were sieved to obtain styrene resin particles (b) having a particle diameter of 0.2 to 0.4 mm as seed particles.

  Next, in a polymerization vessel equipped with a stirrer having an internal volume of 5 liters, 2000 parts by mass of water, 2000 parts by mass of the styrene resin particles (b), 6.0 parts by mass of magnesium pyrophosphate as a suspension stabilizer, and an anionic surfactant As a result, 0.3 parts by mass of calcium dodecylbenzenesulfonate was supplied and heated to 60 ° C. with stirring.

  Next, 126 parts by mass of normal pentane as a foaming agent was pressed into the polymerization vessel, and then the temperature was raised to 120 ° C. to complete the reaction.

  After cooling to 30 ° C. or lower, taking out from the polymerization vessel and drying, it was left in a constant temperature room at 13 ° C. for 5 days to obtain expandable styrene resin particles.

(Foam)
Subsequently, zinc stearate and hydroxystearic acid triglyceride were coated as surface treatment agents on the surface of the expandable styrene resin particles.

Next, the foamed resin particles were obtained by foaming to a bulk density of 0.033 g / cm ³ using a pre-foaming device and then aging at 20 ° C. for 24 hours. The obtained foamed resin particles were inferior in recoverability.

[Comparative Example 2]
Instead of the acrylate sample of Example 1, 3.0 parts by mass of benzoyl peroxide and 1.5 parts by mass of t-butylperoxybenzoate as polymerization initiators were added to 200 parts by mass of butyl acrylate and 100 parts by mass of styrene. Expanded resin particles were obtained in the same manner as in Example 1 except that the dissolved one was used. A polymer derived from butyl acrylate could not be observed in the obtained expandable resin particles, and the recoverability was poor.

[Comparative Example 3]
A polymerization vessel equipped with a stirrer with an internal capacity of 100 liters is supplied with 40000 parts by mass of water, 100 parts by mass of tricalcium phosphate as a suspension stabilizer, and 2.0 parts by mass of calcium dodecylbenzenesulfonate as an anionic surfactant, while stirring. After adding 40000 parts by mass of a monomer and 96.0 parts by mass of benzoyl peroxide and 28.0 parts by mass of t-butylperoxybenzoate as a polymerization initiator, the temperature was raised to 90 ° C. to polymerize. And it hold | maintained at this temperature for 6 hours, and also, after heating up to 125 degreeC, it cooled after 2 hours, and obtained the styrene-type resin particle (a).

  The styrene resin particles (a) were sieved to obtain styrene resin particles (b) having a particle diameter of 0.2 to 0.4 mm as seed particles.

  Next, in a polymerization vessel equipped with a stirrer having an internal volume of 5 liters, 2000 parts by mass of water, 500 parts by mass of the styrene resin particles (b), 6.0 parts by mass of magnesium pyrophosphate as a suspension stabilizer, and an anionic surfactant As a result, 0.3 parts by mass of calcium dodecylbenzenesulfonate was supplied and heated to 70 ° C. with stirring.

  Next, 2.0 parts by mass of benzoyl peroxide and 1.0 part by mass of t-butylperoxybenzoate as a polymerization initiator were dissolved in 200 parts by mass of butyl acrylate and supplied to the 5 liter polymerization vessel. Then, it was absorbed into the seed particles and held at 70 ° C. for 90 minutes. Then, while maintaining the polymerization vessel at 90 ° C., 6.0 parts by mass of benzoyl peroxide and 1.5 parts by mass of t-butylperoxybenzoate as a polymerization initiator were dissolved in 1500 g of styrene at a constant rate over 5 hours. The polymerization was carried out in the seed particles while supplying to the polymerization vessel. Next, 126 parts by mass of normal pentane as a blowing agent was injected into the polymerization vessel, and then the temperature was raised to 120 ° C. to complete the reaction. After cooling to 30 ° C. or lower, taking out from the polymerization vessel and drying, it was left in a thermostatic chamber at 13 ° C. for 5 days to obtain expandable styrene resin particles. The average particle diameter of the butyl acrylate polymer inside the obtained expandable styrene resin particles was 210 nm, but the butyl acrylate polymer was radially oriented from the surface of the expandable styrene resin particles toward the center. 15% (ratio with respect to the radius) of the resin particles were localized at the center of the expandable styrene resin particles. The compression recovery rate of the expanded resin particles was 78%, and sufficient recoverability was not obtained.

  1: Bag body, 2: Styrofoam resin particles, 10: Filler

Claims (14)

Expandable styrene resin particles containing a styrene resin and a foaming agent,
The expandable and styrenic dispersed throughout the resin particles, a copolymer of A acrylic acid ester monomer and a styrene monomer, or, the A acrylic ester polymer and said copolymer Expandable styrenic resin particles comprising fine particles of a mixture. The acrylate polymer includes a butyl acrylate polymer,
The expandable styrene resin particle according to claim 1, wherein the acrylate monomer includes butyl acrylate.   The expandable styrene resin according to claim 1 or 2, wherein the content of the fine particles is 5 to 30% by weight with respect to the total amount of the components other than the foaming agent of the expandable styrene resin particles. particle. Expanded styrene resin particles containing styrene resin in which bubbles are formed,
Wherein in the entire foamed styrene resin particles, into bubble film of the styrene-based resin surrounding the bubble, copolymers of A acrylic acid ester monomer and a styrene monomer, or, A acrylic acid ester Expanded styrenic resin particles, wherein fine particles of a mixture of a polymer and the copolymer are present. The acrylate polymer includes a butyl acrylate polymer,
The expanded styrene resin particles according to claim 4, wherein the acrylate monomer includes butyl acrylate.   The expanded styrene resin particles according to claim 4 or 5, wherein the content of the fine particles is 5 to 30% by weight. A bag,
A filler comprising the expanded styrene resin particles according to any one of claims 4 to 6, which is filled in the bag.   The filler according to claim 7, wherein the filler is a cushioning material or a heat insulating material. In a dispersion in which styrene resin seed particles are dispersed in water, an acrylic ester monomer or a monomer mixture of an acrylic ester monomer and a styrene monomer is used as the seed particle. The monomer or monomer mixture is supplied in an amount of 5 to 45 parts by weight with respect to 100 parts by weight, the monomer or monomer mixture is polymerized in the seed particles, and the seed In the particles, an acrylic ester polymer, a copolymer of an acrylic ester monomer and a styrene monomer, or a mixture of the acrylic ester polymer and the copolymer is minute. Forming a particle to produce a microparticle-containing styrenic resin particle;
Without performing a step of further growing the fine particle-containing styrene resin particles by polymerization after the fine particle formation step, or in the middle of the fine particle formation step, a foaming agent is added to the fine particle-containing styrene resin particles. A method for producing expandable styrene resin particles, comprising an impregnation step.   The method for producing expandable styrene resin particles according to claim 9, wherein the acrylate ester monomer includes butyl acrylate. The expandable styrene resin particle manufactured by the manufacturing method of the expandable styrene resin particle of Claim 9 or 10 . Expanded styrene resin particles comprising a foaming step of foaming expandable styrene resin particles produced by the method for producing expandable styrene resin particles according to claim 9 or 10 to form expanded styrene resin particles. Manufacturing method. The expanded styrene resin particle manufactured by the manufacturing method of the expanded styrene resin particle of Claim 12 . The manufacturing method of a filling body including the filling process which fills the bag with the expanded styrene resin particle manufactured by the manufacturing method of the expanded styrene resin particle of Claim 12 .

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