JP2018145285A - Expandable polystyrene-based resin particle, polystyrene-based pre-expanded particle and expansion-molded body - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an expandable polystyrene-based resin particle that can produce an expansion-molded body in which rubbing noise can be suppressed without applying a large amount of additives and without contaminating pre-expansion machine or molding die.SOLUTION: The problem can be solved by an expandable polystyrene-based resin particle in which the monomer composition is 96.7 pts.wt. or more and 98.8 pts.wt. or less of styrene-based monomer and 1.2 or more and 3.3 pts.wt. or less of polysiloxane-containing macromonomer monomer (the total amount of the styrene-based monomer and the polysiloxane-containing macromonomer monomer is 100 pts.wt.), and in which the polysiloxane-containing macromonomer monomer has a functional group in the side chain, and by copolymerization, the main component of the surface layer portion having a thickness of 30 nm or more and 250 nm or less is polysiloxane.SELECTED DRAWING: None

Description

  The present invention relates to expandable polystyrene resin particles characterized in that the main component of the surface layer portion is polysiloxane. Furthermore, it is related with the polystyrene-type pre-expanded particle | grains and foaming molding which use it.

  Polystyrene foamed molded products are used in a wide variety of applications such as containers, packing materials, architectural civil engineering members, and automobile members because of their light weight and cushioning performance.

  However, a foam molded body made of an expandable polystyrene resin has a problem that an uncomfortable rubbing sound called a cucumber tends to occur when the foam molded bodies are rubbed against each other, another resin member, a steel plate or the like. In particular, in the automobile member field, vibration is likely to be caused by driving on rough roads and the like, and the generation of rubbing noise is a cause of impairing the feeling of use.

  In order to solve such a problem, a foam molded article in which an aliphatic compound or a silicone compound is applied to the surface or kneaded into resin particles is disclosed. For example, Patent Document 1 describes a method for suppressing the generation of rubbing noise in a foamed particle molded body composed of pre-foamed particles of a fatty acid amide and a thermoplastic resin pre-foamed particle having a saturated fatty acid and glycerol monoester attached to the surface.

  Patent Document 2 describes a method of suppressing the generation of rubbing sound with a foamed particle molded body made of foamed particles to which a hydrocarbon wax and dimethylpolysiloxane are adhered.

  However, in these publications, since a large amount of the lubricating component is applied to the surface of the foamed particles, the deterioration of the rubbing noise prevention performance due to the peeling of these components and the contamination of the preliminary foaming machine and the molding die become problems.

  On the other hand, as an example in which a silicone compound is present on the surface of a resin particle, Patent Document 3 describes a method of reducing the aggregation of expanded particles by coating the surface of expandable particles with dimethylpolysiloxane. Patent Document 4 describes a method of uniformly foaming foamed particles by uniformly kneading organosiloxane with expandable polystyrene resin particles to obtain a foamed molded article having excellent mechanical strength and heat insulation. .

  However, when considering the suppression of rubbing noise, the effect cannot be obtained by adding a small amount as described in these patent documents.

  Moreover, it describes in the prior art documents 5-8 as an example of copolymerizing a macromonomer with a styrene-type monomer. However, none of these methods are expected to rub against macromonomers and suppress noise.

JP 2013-100443 A Japanese Patent Laying-Open No. 2015-0117155 JP 2013-142106 A JP 2012-214750 A Japanese Patent Laid-Open No. 08-134252 WO 2006/106653 JP 2008-231175 A JP 2011-246588 A

  In view of the situation as described above, the present invention is a foamable thermoplastic resin capable of obtaining a foamed molded product that can suppress rubbing noise without applying a large amount of an additive and without contaminating a preliminary foaming machine or a molding die. The purpose is to obtain particles.

  As a result of intensive studies, the present inventors have completed the present invention by copolymerizing polysiloxane only on the polystyrene particle surface in order to obtain a foamed molded product capable of suppressing rubbing noise. That is, the present invention is as follows.

  In the first aspect of the present invention, the monomer composition is 96.7 parts by weight or more and 98.8 parts by weight or less of the styrene monomer, and 1.2 parts by weight or more and 3.3 parts by weight or less of the polysiloxane-containing macromonomer monomer. (The total amount of the styrene monomer and the polysiloxane-containing macromonomer monomer is 100 parts by weight), and the polysiloxane-containing macromonomer monomer has a functional group in the side chain and is copolymerized. And the main component of the surface layer part having a thickness of 30 nm to 250 nm is polysiloxane.

  A second aspect of the present invention relates to the expandable polystyrene resin particles according to the first aspect, wherein the functional group is a methacryloyl group.

  A third aspect of the present invention is the expandable polystyrene system according to the first or second aspect, characterized in that the weight average molecular weight determined using GPC as a component soluble in THF is 200,000 or more and 400,000 or less. It relates to resin particles.

  The fourth of the present invention relates to the expandable polystyrene resin particles according to the first to third inventions, wherein the amount of the remaining monomer monomer is 1000 ppm or less.

  According to a fifth aspect of the present invention, the weight average molecular weight determined by using GPC of polysiloxane which is the main chain of the polysiloxane-containing macromonomer is from 20,000 to 500,000. This relates to expandable polystyrene resin particles.

  6th of this invention is related with the polystyrene-type pre-expanded particle characterized by pre-expanding the expandable polystyrene-type resin particle in any one of 1st-5th invention.

  7th of this invention is related with the foaming molding formed by shape | molding the polystyrene-type pre-expanded particle of 6th invention description.

  ADVANTAGE OF THE INVENTION According to this invention, the expandable polystyrene-type resin particle from which the foaming molding which can suppress a rubbing sound can be obtained, without apply | coating an attachment agent in large quantities and without contaminating a preliminary | backup foaming machine and a shaping die.

  The expandable polystyrene resin particles of the present invention have a monomer composition of 96.7 parts by weight or more and 98.8 parts by weight or less of the styrene monomer, and 1.2 to 3.3 parts by weight of the polysiloxane-containing macromonomer monomer. (The total amount of the styrene monomer and the polysiloxane-containing macromonomer monomer is 100 parts by weight), and the polysiloxane-containing macromonomer monomer has a functional group in the side chain and is copolymerized. The main component of the surface layer portion having a thickness of 30 nm or more and 250 nm or less is polysiloxane.

  The monomer composition in the base resin constituting the expandable polystyrene resin particles in the present invention is 96.7 parts by weight or more and 98.8 parts by weight or less of the styrene monomer, and the polysiloxane-containing macromonomer monomer 1. 2 parts by weight or more and 3.3 parts by weight or less (total amount of styrene monomer and polysiloxane-containing macromonomer monomer is 100 parts by weight), more preferably 97.5 parts by weight of styrene monomer The amount is 98.5 parts by weight or less and 1.5 to 2.5 parts by weight of the polysiloxane-containing macromonomer monomer. When the ratio of the polysiloxane-containing monomer component is large, the foaming agent tends to come off, and the foamability and moldability tend to be inferior, making it difficult to obtain a foamed molded article having a beautiful surface. If the polysiloxane-containing monomer component is small, the rubbing noise suppression performance is not sufficiently exhibited.

  As the styrene monomer used in the present invention, for example, styrene derivatives such as styrene, α-methylstyrene, paramethylstyrene, t-butylstyrene, chlorostyrene, and the like can be used. These styrene monomers may be used alone or in combination of two or more. In particular, styrene is preferable from the viewpoint of good foamability and moldability.

  In the present invention, a monomer that can be copolymerized with styrene may be used as the styrenic monomer as long as the effects of the present invention are not impaired. Examples of components that can be copolymerized with styrene include acrylic acid such as methyl acrylate, butyl acrylate, methyl methacrylate, ethyl methacrylate, and cetyl methacrylate, and esters of methacrylic acid, or various types such as acrylonitrile, dimethyl fumarate, and ethyl fumarate. Also included are difunctional monomers such as a monomer, divinylbenzene, and alkylene glycol dimethacrylate. One or more of these copolymerizable components may be used for copolymerization.

  Since these are added to the styrene monomer in the present invention, the total amount of styrene and other monomers must be 96.7 parts by weight or more and 98.8 parts by weight or less.

  The polysiloxane-containing macromonomer monomer used in the present invention has a functional group in the side chain. The functional group is preferably a vinyl group, and more preferably a methacryloyl group.

  Examples of polysiloxane-containing macromonomer monomers include polyorganosiloxanes such as polydimethylsiloxane, polymethylphenylsiloxane, and polydimethylsiloxane-diphenylsiloxane copolymer, and some of the side chain alkyl groups are substituted with hydrogen atoms. Polyorganohydrogensiloxane can be used. Of these, polydimethylsiloxane, polymethylphenylsiloxane, and polydimethylsiloxane-diphenylsiloxane copolymer are preferable, and polydimethylsiloxane is most preferable because it can be easily obtained economically.

  The polysiloxane-containing macromonomer monomer has a functional group in order to copolymerize with the styrene monomer. More preferably, the side chain has at least a plurality of functional groups per molecule.

  A method for obtaining the polysiloxane-containing macromonomer monomer is not particularly limited, and a solution polymerization method, a suspension polymerization method, an emulsion polymerization method, or the like is used.

  For example, a method of polymerizing a cyclic, linear or branched organosiloxane, preferably a cyclic organosiloxane, using a catalyst such as an acid, an alkali, a salt or a fluorine compound can be mentioned. The weight average molecular weight (Mw) in terms of polystyrene of the organosiloxane used for the polymerization is preferably 20,000 or less, more preferably 10,000 or less. In the above method, a method using a silane having a functional group and / or a cyclic, linear or branched organosiloxane having a functional group together with the organosiloxane can be more preferably mentioned.

  Alternatively, the polysiloxane having a polystyrene-equivalent weight average molecular weight (Mw) of preferably 20,000 or more, more preferably 50,000 or more, and more preferably 100,000 or more in a solution, slurry, or emulsion and preferably has a functional group. Examples thereof include a method of equilibrating a silane and / or a cyclic, linear or branched organosiloxane having a functional group in the presence of the same catalyst as described above.

  The production method of the polysiloxane-containing macromonomer can be obtained by, for example, a known emulsion polymerization method described in JP-A No. 2006-291122.

  That is, a cyclic siloxane represented by 1,3,5,7-octamethylcyclotetrasiloxane, and / or a bifunctional silane having a hydrolyzable group such as dimethyldimethoxysilane, methyltriethoxysilane, tetra Trifunctional or higher functional alkoxysilanes such as propyloxysilane, condensates of trifunctional or higher functional silanes such as methyl orthosilicate, and, if necessary, mercaptopropyldimethoxymethylsilane, acryloyloxypropyldimethoxymethylsilane, methacryloyloxypropyldimethoxymethylsilane Polysiloxane-containing macromonomers can be obtained using functional groups such as vinyldimethoxymethylsilane and vinylphenyldimethoxymethylsilane. Among these, methacryloyloxypropyldimethoxymethylsilane is preferable from the viewpoint of copolymerization with a styrene monomer.

  The amount of the functional group used is preferably 0.03 mol% or more and 5 mol% or less, more preferably 0.1 mol% or more and 3 mol% or less in terms of the siloxane unit in the polyorganosiloxane obtained. If the functional group is less than 0.03 mol%, the reactivity with the styrene monomer is low, so that copolymerization tends to be difficult, and if it exceeds 5 mol%, polymerization between polysiloxane-containing macromonomers increases. It tends to be difficult to obtain a copolymer with styrene.

The viscosity of the polysiloxane-containing macromonomer monomer is preferably 700 mm ² / s or more at 25 ° C., more preferably 10,000 mm ² / s or more as the kinematic viscosity. The higher the viscosity is, the longer the siloxane chain is, and therefore, the rubbing sound suppression performance is more likely to be exhibited.

  The molecular weight of the polysiloxane, which is the main chain of the polysiloxane-containing macromonomer monomer, is preferably from 20,000 to 500,000, more preferably from 550,000 to 300,000 in terms of polystyrene-converted weight average molecular weight determined using GPC. preferable. The higher the molecular weight, the longer the siloxane chain, and the more likely it is to exhibit rubbing noise suppression performance. However, if the viscosity is too high, the handling properties will deteriorate and polymerization will become difficult.

  In the present invention, the polysiloxane which is the main component of the surface layer portion having a thickness of 30 nm or more and 250 nm or less is a state in which a polysiloxane component is contained in an amount of 50% by weight or more, preferably 70% by weight or more, more preferably 90% by weight or more.

  If the polysiloxane as the main component is less than 50% by weight, the rubbing sound suppression performance tends to be difficult to be exhibited.

  The polysiloxane-containing monomer may be added at any stage of the polymerization, but in order to allow it to be present on the surface more and to obtain a rubbing noise suppression performance, the polysiloxane-containing monomer is added at the end of the addition of the styrenic monomer. It is preferable to add a monomer.

  The expandable polystyrene resin particles of the present invention preferably have a polystyrene-equivalent weight average molecular weight of 200,000 or more and 400,000 or less, more preferably 250,000 or more and 350,000 or less, as measured by GPC which is a component soluble in THF. If the weight average molecular weight is low, it tends to be inferior in mechanical strength such as compressive strength when used as a member, and if it is high, it is difficult to obtain a molded article having good surface properties. In the present invention, bifunctional monomers such as divinylbenzene and hexanediol di (meth) acrylate can be used for adjusting the molecular weight.

  The expandable polystyrene resin particles of the present invention preferably have a residual monomer monomer amount of 1000 ppm or less. When the monomer component exceeds 1000 ppm, it is not preferable for the medical field, the packaging material field that comes into direct contact with food, or for automobiles and building components, but it tends to hinder the shortening of the cooling time in the cooling process.

  As a method for producing the expandable resin particles of the present invention, a method in which a styrene monomer is polymerized in an aqueous suspension, followed by suspension polymerization, followed by addition and polymerization of a polysiloxane-containing macromonomer monomer, Alternatively, by continuously or intermittently adding a styrene monomer and a polysiloxane-containing monomer to an aqueous suspension containing polystyrene resin particles, the styrene monomer and polysiloxane are added to the polystyrene resin particles. Examples include a so-called seed polymerization method in which a siloxane-containing macromonomer monomer is impregnated and polymerized.

  An aqueous suspension refers to a state in which resin particles and monomer droplets are dispersed in water or an aqueous solution. Water-soluble surfactants and monomers may be dissolved in water. Insoluble dispersants, initiators, chain transfer agents, crosslinking agents, bubble regulators, flame retardants, plasticizers, and the like may be dispersed together.

  The weight ratio of resin to water is preferably 1.0 / 0.6 to 1.0 / 3.0 as the ratio of resin / water to be obtained.

  Examples of the dispersant that can be used for suspension polymerization include poorly water-soluble inorganic salts such as tricalcium phosphate, magnesium pyrophosphate, hydroxyapatite, and kaolin, and water-soluble polymers such as polyvinyl alcohol, methyl cellulose, polyacrylamide, and polyvinyl pyrrolidone. In the case of using a poorly water-soluble inorganic salt, it is effective to use an anionic surfactant such as α-olefin sulfonic acid soda and dodecylbenzene sulfonic acid soda together. These dispersants may be added during the polymerization as required.

  The amount of the dispersant used depends on the type, but the water-insoluble inorganic salt is 0.1 to 3.0 parts by weight with respect to 100 parts by weight of water, and 30 ppm for the anionic surfactant or water-soluble polymer. It is preferably 500 ppm or less.

  In the suspension polymerization of the present invention, it is preferable that after the first stage polymerization is performed and the main reaction is performed, the residual monomer is reduced by the second stage polymerization reaction at a higher temperature than the first stage.

  As the polymerization initiator used in the first stage polymerization, radical generating polymerization initiators generally used for the production of thermoplastic polymers can be used. Typical examples include benzoyl peroxide and lauroyl. Peroxide, t-butyl peroxybenzoate, isopropyl-t-butyl peroxycarbonate, butyl perbenzoate, t-butyl peroxy-2-ethylhexanoate, t-butyl perpivalate, t-butyl peroxyisopropyl Carbonate, di-t-butylperoxyhexahydroterephthalate, 1,1-di (t-butylperoxy) 3,3,5-trimethylcyclohexane, 1,1-bis (t-amylperoxy) -3,3 , 5-trimethylcyclohexane, 1,1-di (t-butylperoxy) cyclohexane Sun, t- butyl peroxy-2-ethylhexyl monocarbonate, and organic peroxides such as azobisisobutyronitrile, an azo compound such as azo-bis-dimethyl valeronitrile. These polymerization initiators may be used alone or in combination of two or more.

  Examples of the blowing agent include aliphatic hydrocarbons that are hydrocarbons having 3 to 5 carbon atoms, such as propane, isobutane, normal butane, isopentane, normal pentane, and neopentane, for example, ozone destruction of difluoroethane, tetrafluoroethane, and the like. Examples thereof include volatile foaming agents such as hydrofluorocarbons having a coefficient of zero. These foaming agents can be used in combination. The amount used is preferably 4 to 10 parts by weight, more preferably 5 to 9 parts by weight, with respect to 100 parts by weight of the polystyrene resin particles. If the amount of the foaming agent is small, it is difficult to obtain the expansion ratio, and if the amount of the foaming agent is large, the resin tends to aggregate in the foaming agent impregnation step.

  As the additive used in the present invention, a solvent, a plasticizer, a bubble regulator, an external additive, a flame retardant, and the like can be used depending on the purpose.

  Examples of the solvent include those having a boiling point of 50 ° C. or higher, and C6 or higher aliphatic hydrocarbons such as toluene, hexane, and heptane, and C6 or higher alicyclic hydrocarbons such as cyclohexane and cyclooctane.

  Examples of the plasticizer include high-boiling plasticizers having a boiling point of 200 ° C. or higher. Examples thereof include vegetable oils such as palm kernel oil, aliphatic esters such as dioctyl adipate and dibutyl sebacate, organic hydrocarbons such as liquid paraffin and cyclohexane.

  Examples of the air conditioner include aliphatic bisamides such as methylene bis stearic acid amide and ethylene bis stearic acid amide, polyethylene wax, and the like.

  Specific examples of the external additive include, for example, fatty acid triglycerides such as lauric acid triglyceride, stearic acid triglyceride, linoleic acid triglyceride, hydroxystearic acid triglyceride, lauric acid diglyceride, stearic acid diglyceride, linoleic acid diglyceride, and lauric acid diglyceride, lauric acid Fatty acid monoglycerides such as monoglyceride, stearic acid monoglyceride, linoleic acid monoglyceride, vegetable oil such as castor oil, soybean oil, olive oil, fatty acid metal salts such as zinc stearate, calcium stearate, magnesium stearate, aluminum stearate, zinc laurate, calcium laurate , Polyoxyethylene cetyl ether, polyoxyethylene oleyl ether Polyoxyethylene stearyl ether, polyoxyethylene laurate, polyoxyethylene palmitate, polyoxyethylene stearate, etc. and nonionic surfactants such as polyoxyethylene oleate and the like. These external additives and attachments may be used alone or in combination of two or more. Among them, stearic acid triglyceride and castor oil are preferable in order to promote the fusion of the foam. These external additives and attachments may be added to the aqueous system when impregnated with the foaming agent, or may be added and coated after dehydration or after drying, regardless of the coating method. A preferable coating method is a method of attaching by drying and coating by mixing and stirring.

  As the flame retardant and flame retardant aid used in the present invention, known and conventional ones can be used.

  Specific examples of the flame retardant include, for example, halogenated aliphatic hydrocarbon compounds such as hexabromocyclododecane, tetrabromobutane, hexabromocyclohexane, tetrabromobisphenol A, tetrabromobisphenol F, 2,4,6-tri Brominated phenols such as bromophenol, tetrabromobisphenol A-bis (2,3-dibromopropyl ether), tetrabromobisphenol A-bis (2,3-dibromo-2-methylpropyl ether), tetrabromobisphenol A- Brominated phenol derivatives such as diglycidyl ether, 2,2-bis [4 ′ (2 ″, 3 ″ -dibromoalkoxy) -3 ′, 5′-dibromophenyl] -propane, brominated styrene / butadiene block copolymers , Brominated random styrene / butadiene copolymer And brominated butadiene / vinyl aromatic hydrocarbon copolymers such as brominated styrene / butadiene graph and copolymers (for example, disclosed in Chemera's EMERALD 3000 and JP 2009-516019) Is mentioned. These flame retardants may be used alone or in combination of two or more.

  Specific examples of flame retardant aids include initiators such as cumene hydroperoxide, dicumyl peroxide, t-butyl hydroperoxide, 2,3-dimethyl-2,3-diphenylbutane, and the like. .

  The obtained expandable polystyrene resin particles can be made into pre-expanded particles by a general pre-expand method. Specifically, it is placed in a container equipped with a stirrer and heated by a heat source such as water vapor to perform preliminary foaming up to a desired foaming ratio.

  Further, the expandable styrene-based pre-expanded particles can be formed into a foam-molded product by a general in-mold molding method. Specifically, it is filled in a mold that can be closed but cannot be sealed, and is heat-sealed with water vapor to obtain a styrene-based foam molded article.

  The styrenic foamed molded product of the present invention was pre-foamed at a foaming ratio of 45 times, and the rubbing noise when molded was evaluated.

  Examples and Comparative Examples are given below, but the present invention is not limited thereby.

<GPC measurement>
After 0.02 g of expandable polystyrene resin particles were dissolved in 20 ml of tetrahydrofuran (hereinafter sometimes abbreviated as “THF”), the gel component was filtered. Subsequently, only a component soluble in THF is subjected to GPC measurement under the following conditions using a gel permeation chromatograph (GPC), and a GPC measurement chart, weight average molecular weight (Mw) and number average molecular weight ( Mn) was obtained. The obtained value is a relative value in terms of polystyrene.
Measuring device: manufactured by Tosoh Corporation, high-speed GPC device HLC-8220
Column used: Tosoh Corporation, SuperHZM-H x 2, SuperH-RC x 2 Column temperature: 40 ° C, mobile phase: THF (tetrahydrofuran)
Flow rate: 0.35 ml / min, injection volume: 10 μl
Detector: RI.

<Measurement of residual styrene>
The expandable polystyrene resin particles are dissolved in methylene chloride (internal standard cyclopentanol) and the amount of residual styrene (ppm) contained in the expandable styrene resin particles is measured under the following conditions using gas chromatography (GC). Quantified.
Measuring apparatus: Gas chromatography GC-2014 manufactured by Shimadzu Corporation
Column: Capillary column (GL Science Rtx-1)
Column temperature conditions: 50 → 80 ° C. (3 ° C./min), then 80 → 180 ° C. temperature increase (10 ° C./min),
Carrier gas: helium.

<Measurement of thickness of polysiloxane layer of expandable polystyrene resin particles>
In order to remove the unreacted polysiloxane-containing macromonomer monomer, 2 g of expandable polystyrene resin particles were weighed and separated into ethanol-insoluble and soluble components. Ethanol insoluble matter was further separated into hexane insoluble matter and soluble matter, and the insoluble matter was used for TEM observation. For the TEM observation, an ultrathin section was prepared for the cross section including the bead surface by an ultramicrotome under freezing conditions, and the thickness of 10 polysiloxane layers in the cross section was measured to calculate an average value.
Frozen ultrathin section preparation (cryo ultra microtome)
Equipment: Leica FC6
Transmission electron microscope (TEM)
Equipment: H-7650 made by Hitachi High-Technologies
Observation conditions: acceleration voltage 100 kV.

<Production of pre-expanded particles>
Expandable polystyrene resin particles classified into a predetermined particle diameter by a sieve are subjected to a bulk magnification of 45 times under a condition of a blowing vapor pressure of 0.09 to 0.12 MPa using a pressure pre-foaming machine “BHP” manufactured by Daikai Kogyo. Then, the mixture was allowed to stand at room temperature for 1 day to obtain pre-expanded particles having a bulk magnification of 45 times.

<Manufacture of foam molding>
The resulting styrene-based pre-expanded particles are molded in-mold with a molding machine “Daisen, KR-57” at a blown vapor pressure of 0.10 MPa, thereby forming a flat plate having a thickness of 50 mm and a length of 400 mm × width of 350 mm. The foamed molded product was obtained.

<Surface property of molded body>
The state of the surface of the foamed molded product was evaluated by visual observation. The larger the numerical value, the more beautiful the surface state with few gaps between particles, and 3 or more expressed with a perfect score of 5 was regarded as acceptable.

5: Gaps are not found 4: Gaps are partly present but are hardly understood 3: Gaps are present in some places, but acceptable as a whole 2: Gaps are conspicuous 1: There are many gaps

<Measurement of static friction coefficient>
A test piece of a single-sided skin having a length of 60 mm, a width of 60 mm, and a thickness of 4 mm was cut out from the obtained foamed molded product using a vertical slicer (manufactured by Sakura Engineering).

  The test piece was stationary for 12 hours in a constant temperature and humidity chamber at a temperature of 23 ° C. and a humidity of 50%. Thereafter, using the surface property tester HEIDON Type: 14FW (manufactured by Shinto Kagaku Co., Ltd.) under the same environment, the specimen is rubbed 10 times with the iron plate under the conditions of a load of 200 g, a reciprocating distance of 50 mm, and a sliding speed of 3000 mm / min. In addition, the average value of the static friction coefficient for each rubbing was obtained.

<Measurement of rubbing sound>
From the obtained foamed molded article, a rectangular parallelepiped test piece having a length of 300 mm, a width of 60 mm, and a thickness of 25 mm was cut out using a vertical slicer (manufactured by Sakura Engineering). Further, a test piece of a triangular prism with double-sided skin having a base of 120 mm, a height of 60 mm, and a thickness of 25 mm was cut out, and both were left in a constant temperature and humidity chamber at a temperature of 23 ° C. and a humidity of 50% for 12 hours. Thereafter, under the same environment, a triangular prism test piece was placed on a rectangular parallelepiped test piece so that the corners hit, and a load of 2000 g was placed on the triangular pyramid test piece. In this state, the test piece was reciprocated 10 times at a speed of 6000 mm / min in a section having a width of 50 mm.

  A wide range and sound pressure of the rubbing sound generated at that time were measured with a microphone. The highest sound pressure in the sound range of 5000 to 20,000 Hz, which humans feel uncomfortable, was accepted as 40 dB or less.

Example 1
<Manufacture of polystyrene resin seed particles>
A reactor equipped with a stirrer was charged with 100 parts by weight of pure water, 0.4 parts by weight of tribasic calcium phosphate, 0.01 parts by weight of sodium dodecylbenzenesulfonate, 0.5 parts by weight of sodium chloride, and 0.1% polyethylene wax as a nucleating agent. After adding 07 parts by weight and stirring to make an aqueous suspension, 0.2 parts by weight of benzoyl peroxide, 1,1-bis (t-butylperoxy) as a polymerization initiator was added to 100 parts by weight of styrene monomer. ) Dissolve 0.2 parts by weight of cyclohexane, add it to the reactor, raise the temperature to 98 ° C., polymerize for 4.5 hours and then cool, take out the contents, dehydrate, dry and screen. Thus, polystyrene resin seed particles having a particle diameter of 0.4 to 0.5 mm were obtained.

<Manufacture of expandable polystyrene resin particles>
In a 6 L autoclave attached to a stirrer, pure water weight 167 parts by weight, tribasic calcium phosphate 0.82 parts by weight, α-olefin sulfonate sodium 0.022 parts by weight, sodium chloride 0.2 parts by weight, t-butylperoxy Stirring was started after charging 0.04 parts by weight of 2-ethylhexyl monocarbonate (10 hours half-life temperature 99 ° C.) and 20 parts by weight of styrene resin seed particles having a particle diameter of 0.4 to 0.5 mm. Subsequently, the temperature was raised to 90 ° C., and then polymerization was performed while charging 0.22 parts by weight of a 30% benzoyl peroxide solution into the reactor over 5 hours and 78.5 parts by weight of styrene monomer over 5 hours and 30 minutes. did. At this time, methacryloyl-containing polysiloxane (methacryloyloxypropyldimethoxymethylsilane content: 2.5% by weight, molecular weight: 200,000) 1.5 at the end of addition of the styrene monomer (5 hours after heating at 90 ° C.) 1.5 Part by weight and 0.075 part by weight of di-t-butylperoxyhexahydroterephthalate were charged over 1 hour and 30 minutes and maintained at 90 ° C. for 30 minutes. Thereafter, the temperature was raised to 120 ° C. and held for 1 hour, then cooled to 98 ° C. and charged with 1.0 part by weight of cyclohexane and 6.5 parts by weight of normal rich butane (normal butane 70%, isobutane 30%). The temperature was raised to ° C. and held for 1.5 hours, and then cooled to 40 ° C. The suspension was taken out, dehydrated, dried, and classified to obtain expandable polystyrene resin particles having a particle size of 0.6 to 1.15 mm.

  The obtained expandable polystyrene resin particles are sieved to obtain expandable polystyrene resin particles having a particle diameter of 0.5 to 1.0 mm, and further with a pressure type pre-foaming machine “BHP-300 (manufactured by Daikai Kogyo)”. Pre-foamed particles having a bulk magnification of 45 times were obtained by pre-foaming. After the pre-expanded particles obtained were cured at room temperature for 1 day, a foamed molded product was obtained with a 300 × 450 × 50 (t) mm size mold using a molding machine “KR-57 (manufactured by Daisen)”. The surface property, static friction coefficient, and rubbing sound of the molded body were evaluated. The evaluation results are shown in Table 1.

(Example 2)
The same as in Example 1 except that 78 parts by weight of styrene monomer, 2.0 parts by weight of methacryloyl-containing polysiloxane and 0.1 part by weight of di-t-butylperoxyhexahydroterephthalate were charged over 2 hours. went. The evaluation results are shown in Table 1.

(Example 3)
Example except that 77.5 parts by weight of styrene monomer, 2.5 parts by weight of methacryloyl-containing polysiloxane and 0.125 parts by weight of di-t-butylperoxyhexahydroterephthalate were charged over 2.5 hours. 1 was performed. The evaluation results are shown in Table 1.

(Example 4)
The same procedure as in Example 1 was conducted except that 77 parts by weight of a styrene monomer, 3 parts by weight of methacryloyl-containing polysiloxane and 0.15 parts by weight of di-t-butylperoxyhexahydroterephthalate were charged over 3 hours. . The evaluation results are shown in Table 1.

(Example 5)
In a 6 L autoclave with a stirrer, 96 parts by weight of water, 0.17 part by weight of tribasic calcium phosphate, 0.048 part by weight of sodium α-olefin sulfonate, brominated butadiene / styrene copolymer ("EMERALD 3000" manufactured by Chemtura Co., Ltd.) as a flame retardant "Brine content 64%) 1.2 parts by weight, 0.2 parts by weight of dicumyl peroxide as a flame retardant aid, 0.1 parts by weight of benzoyl peroxide as a polymerization initiator, t-butylperoxy-2-ethylhexyl mono After charging 0.37 parts by weight of carbonate and 1.4 parts by weight of coconut oil as a plasticizer, 98 parts by weight of styrene was charged, and the temperature was raised to 98 ° C. for polymerization for 5 hours. Subsequently, 2 parts by weight of methacryloyl-containing polysiloxane (methacryloyloxypropyldimethoxymethylsilane content: 2.5% by weight, molecular weight: 200,000) and 0.1 part by weight of di-t-butylperoxyhexahydroterephthalate are taken over 2 hours. Added for further 30 minutes. Furthermore, 1.0 part by weight of cyclohexane and 6.5 parts by weight of normal rich butane (normal butane 70%, isobutane 30%) were added, the temperature was raised to 120 ° C., and impregnation and polymerization were performed for 4 hours. Then, after cooling to 40 ° C., expandable polystyrene resin particles were obtained by washing, dehydrating and drying.

  The obtained expandable polystyrene resin particles are sieved to obtain expandable polystyrene resin particles having a particle diameter of 0.5 to 1.0 mm, and further with a pressure type pre-foaming machine “BHP-300 (manufactured by Daikai Kogyo)”. Pre-foamed particles having a bulk magnification of 45 times were obtained by pre-foaming. After the pre-expanded particles obtained were cured at room temperature for 1 day, a foamed molded product was obtained with a 300 × 450 × 50 (t) mm size mold using a molding machine “KR-57 (manufactured by Daisen)”. The surface property, static friction coefficient, and rubbing sound of the molded body were evaluated. The evaluation results are shown in Table 1.

Example 6
Instead of 78.5 parts by weight of styrene monomer, 73 parts by weight of styrene monomer and 5 parts by weight of butyl acrylate are mixed in advance, and a total of 80 parts by weight of monomer is added over 5 hours and 30 minutes. Then, the same procedure as in Example 1 was carried out except that 2.0 parts by weight of methacryloyl-containing polysiloxane and 0.1 parts by weight of di-t-butylperoxyhexahydroterephthalate were charged over 2 hours. The evaluation results are shown in Table 1.

(Comparative Example 1)
The same procedure as in Example 1 was carried out except that the styrene monomer was changed to 80 parts by weight and no methacryloyl-containing polysiloxane and di-t-butylperoxyhexahydroterephthalate were used. The evaluation results are shown in Table 1.

(Comparative Example 2)
Example 1 was performed except that 79 parts by weight of a styrene monomer, 1 part by weight of a methacryloyl-containing polysiloxane and 0.05 part by weight of di-t-butylperoxyhexahydroterephthalate were charged over 1 hour. . The evaluation results are shown in Table 1.

(Comparative Example 3)
When 76.5 parts by weight of a styrenic monomer, 3.5 parts by weight of methacryloyl-containing polysiloxane and 0.175 parts by weight of di-t-butylperoxyhexahydroterephthalate were charged over 3 hours, the contents aggregated. However, resin particles could not be obtained.

(Comparative Example 4)
3.0 hours by weight of methacrylic dimethylpolysiloxane at both ends (X-22-164B (viscosity 55 mm ² / s (25 ° C.)) and 0.15 parts by weight of di-t-butylperoxyhexahydroterephthalate for 3.0 hours The procedure was the same as in Example 1, except that it was charged over the course of time.

(Comparative Example 5)
2 parts by weight of methacrylic dimethylpolysiloxane having one end (KF-2012 (viscosity 60 mm ² / s (25 ° C.)) and 0.1 part by weight of di-t-butylperoxyhexahydroterephthalate were charged over 2.0 hours. Except for this, the same procedure as in Example 1 was performed.

Claims (7)

The monomer composition is 96.7 parts by weight or more and 98.8 parts by weight or less of the styrene monomer, and 1.2 parts by weight or more and 3.3 parts by weight or less of the polysiloxane-containing macromonomer monomer. The total amount of the polymer and the polysiloxane-containing macromonomer monomer is 100 parts by weight), the polysiloxane-containing macromonomer monomer has a functional group in the side chain, and the thickness is 30 nm to 250 nm by copolymerization. Expandable polystyrene resin particles, characterized in that the main component of the surface layer part is polysiloxane. 2. The expandable polystyrene resin particle according to claim 1, wherein the functional group is a methacryloyl group. 3. The expandable polystyrene resin particles according to claim 1 or 2, wherein the weight average molecular weight determined using GPC as a component soluble in THF is 200,000 or more and 400,000 or less. The expandable polystyrene resin particles according to any one of claims 1 to 3, wherein the amount of the monomer monomer remaining is 1000 ppm or less. The expandable polystyrene according to any one of claims 1 to 4, wherein the weight average molecular weight determined using GPC of polysiloxane which is a main chain of the polysiloxane-containing macromonomer is 20,000 to 500,000. Resin particles. A polystyrene-based pre-expanded particle obtained by pre-expanding the expandable polystyrene-based resin particle according to any one of claims 1 to 5. A foam-molded product obtained by molding the polystyrene-based pre-expanded particles according to claim 6.