JP6847713B2 - Effervescent polystyrene-based resin particles, polystyrene-based pre-expanded particles and foamed molded products - Google Patents

Description

The present invention relates to effervescent polystyrene-based resin particles characterized in that the main component of the surface layer portion is polysiloxane. Furthermore, the present invention relates to polystyrene-based prefoamed particles and foamed molded products using the same.

Polystyrene-based foam molded products are widely used in containers, packaging materials, building civil engineering materials, automobile materials, etc. due to their light weight and cushioning performance.

However, the foamed molded product made of foamable polystyrene resin has a problem that when the foamed molded products are rubbed against each other, other resin members, steel plates, or the like, an unpleasant rubbing noise called squeaking is likely to occur. In particular, in the field of automobile parts, vibration is likely to occur when traveling on rough roads, and the generation of rubbing noise causes a loss of usability.

In order to solve such a problem, a foam molded product in which an aliphatic compound or a silicone compound is coated on the surface or kneaded with resin particles is disclosed. For example, Patent Document 1 describes a method of suppressing the generation of rubbing noise with a foamed particle molded product composed of fatty acid amide and thermoplastic resin pre-foamed particles in which a monoester of saturated fatty acid and glycerin is adhered to the surface.

Further, Patent Document 2 describes a method of suppressing the generation of rubbing noise with a foamed particle molded body composed of foamed particles to which a hydrocarbon wax and dimethylpolysiloxane are attached.

However, in these publications, since a large amount of lubricating components are applied to the surface of the foamed particles, there are problems such as deterioration of the rubbing noise prevention performance due to peeling of these components and contamination of the pre-foaming machine and the molding die.

On the other hand, as an example of allowing the silicone compound to exist on the surface of the resin particles, Patent Document 3 describes a method of reducing the aggregation of the foamed particles by coating the surface of the foamable particles with dimethylpolysiloxane. Further, Patent Document 4 describes a method of uniformly kneading organosiloxane into foamable polystyrene-based resin particles to homogenize the bubbles of the foamed particles and obtain a foamed molded product having excellent mechanical strength and heat insulating properties. ..

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

Further, Examples of Copolymerizing a Macromonomer with a Styrene-based Monomer are described in Prior Documents 5 to 8. However, none of these methods is expected to have a rubbing sound suppression performance on the macromonomer.

Japanese Unexamined Patent Publication No. 2013-100443 Japanese Unexamined Patent Publication No. 2015-017155 Japanese Unexamined Patent Publication No. 2013-142106 Japanese Unexamined Patent Publication No. 2012-214750 Japanese Unexamined Patent Publication No. 08-134252 WO2006 / 106653 Japanese Unexamined Patent Publication No. 2008-231175 Japanese Unexamined Patent Publication No. 2011-246588

In view of the above circumstances, the present invention provides a foamable thermoplastic resin capable of obtaining a foamed molded product capable of suppressing rubbing noise without applying a large amount of an adhering agent and without contaminating a prefoaming machine or a molding die. The purpose is to obtain particles.

As a result of diligent studies, the present inventors have completed the present invention by copolymerizing polysiloxane only on the surface of polystyrene particles 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-based 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-based 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 present invention relates to effervescent polystyrene-based resin particles having a thickness of 30 nm or more and 250 nm or less, wherein the main component of the surface layer portion is polysiloxane.

The second aspect of the present invention relates to the effervescent polystyrene-based resin particles according to the first invention, wherein the functional group is a methacryloyl group.

The third aspect of the present invention is the foamable polystyrene system according to the first or second invention, wherein the weight average molecular weight determined by using GPC, which is a component soluble in THF, is 200,000 or more and 400,000 or less. Regarding resin particles.

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

A fifth aspect of the present invention is described in the fifth aspect of the present invention, wherein the weight average molecular weight determined by using GPC of polysiloxane, which is the main chain of the polysiloxane-containing macromonomer, is 20,000 or more and 500,000 or less. Regarding foamable polystyrene-based resin particles.

A sixth aspect of the present invention relates to polystyrene-based pre-expanded particles, which are obtained by pre-foaming the effervescent polystyrene-based resin particles according to any one of the first to fifth inventions.

A seventh aspect of the present invention relates to a foamed molded product, which is formed by molding the polystyrene-based prefoamed particles according to the sixth invention.

According to the present invention, it is possible to obtain foamable polystyrene-based resin particles capable of obtaining a foamed molded product capable of suppressing rubbing noise without applying a large amount of an adhering agent and without contaminating a prefoaming machine or a molding die.

The foamable polystyrene-based 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-based monomer, and 1.2 or more and 3.3 parts by weight of the polysiloxane-containing macromonomer monomer. Parts or less (the total amount of the styrene-based 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 is polysiloxane, which has a thickness of 30 nm or more and 250 nm or less.

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

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

In the present invention, a monomer copolymerizable with styrene may be used as the styrene-based monomer as long as the effect of the present invention is not impaired. Examples of the components that can be copolymerized with styrene include esters of acrylic acid and methacrylic acid such as methyl acrylate, butyl acrylate, methyl methacrylate, ethyl methacrylate and cetyl methacrylate, and various simple substances such as acrylonitrile, dimethyl fumarate and ethyl fumarate. It also includes difunctional monomers such as weights, divinylbenzene and alkylene glycol dimethacrylate. One or two or more of these copolymerizable components may be used for copolymerization.

Since these are added to the styrene-based 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, more preferably a methacryloyl group.

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

The polysiloxane-containing macromonomer monomer has a functional group because it copolymerizes with a styrene-based monomer. It is more preferable to have at least a plurality of functional groups per molecule in the side chain.

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

A method for producing a polysiloxane-containing macromonomer can be obtained, for example, by a known emulsion polymerization method described in JP-A-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, and if necessary, methyltriethoxysilane and tetra. Trifunctional or higher alkoxysilanes such as propyloxysilane, condensates of trifunctional or higher silanes such as methyl orthosilicate, and optionally mercaptopropyldimethoxymethylsilane, acryloyloxypropyldimethoxymethylsilane, methacryloyloxypropyldimethoxymethylsilane , Vinyldimethoxymethylsilane, Vinylphenyldimethoxymethylsilane, and other functional groups can be used to obtain polysiloxane-containing macromonomonates. Of these, methacryloyloxypropyldimethoxymethylsilane is preferable from the viewpoint of copolymerization with a styrene-based monomer.

The amount of the functional group to be 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 obtained polyorganosiloxane. If the functional group is less than 0.03 mol%, the reactivity with the styrene-based monomer is low and it tends to be difficult to copolymerize. If it is more than 5 mol%, the polymerization of 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 and more preferably 10,000 mm ² / s or more at 25 ° C. as the kinematic viscosity. The higher the viscosity, the longer the siloxane chain, and the more likely it is that the rubbing noise suppression performance will be exhibited.

The molecular weight of polysiloxane, which is the main chain of the polysiloxane-containing macromonomer monomer, is preferably 20,000 or more and 500,000 or less, and more preferably 55,000 or more and 300,000 or less in terms of polystyrene-equivalent weight average molecular weight obtained by using GPC. preferable. The higher the molecular weight, the longer the siloxane chain, so the rubbing noise suppression performance is likely to be exhibited, but if the viscosity is too high, the handleability deteriorates and polymerization becomes difficult.

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 in the present invention is in a state where the polysiloxane component is contained in an amount of 50% by weight or more, preferably 70% by weight or more, and more preferably. 90% by weight or more.

If the content of polysiloxane, which is the main component, is less than 50% by weight, the rubbing noise suppression performance tends to be difficult to develop.

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

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

The foamable polystyrene-based resin particles of the present invention preferably have a residual monomer monomer amount of 1000 ppm or less. Monomer If 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 the parts of automobiles and buildings, and it tends to hinder the shortening of the cooling time in the cooling process.

As a method for producing the foamable resin particles of the present invention, a method of polymerizing a styrene-based monomer in an aqueous suspension, suspend-polymerizing it, and then adding a polysiloxane-containing macromonomer monomer to polymerize it. Alternatively, by continuously or intermittently adding the styrene-based monomer and the polysiloxane-containing monomer to the aqueous suspension containing the polystyrene-based resin particles, the styrene-based monomer and the poly are added to the polystyrene-based resin particles. Examples thereof include a so-called seed polymerization method in which a siloxane-containing macromonomer monomer is impregnated and polymerized.

The aqueous suspension refers to a state in which resin particles and monomer droplets are dispersed in water or an aqueous solution, and a water-soluble surfactant or monomer may be dissolved in water, or water. Insoluble dispersants, initiators, chain transfer agents, cross-linking agents, bubble modifiers, 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 obtained resin / water ratio.

Examples of the dispersant that can be used for suspension polymerization include poorly water-soluble inorganic salts such as calcium tertiary phosphate, magnesium pyrophosphate, hydroxyapatite, and kaolin, and water-soluble polymers such as polyvinyl alcohol, methyl cellulose, polyacrylamide, and polyvinylpyrrolidone. When a poorly water-soluble inorganic salt is used, it is effective to use an anionic surfactant such as α-olefin sulfonic acid sodium and dodecylbenzene sulfonic acid sodium in combination. These dispersants may be added in the middle of the polymerization if necessary.

The amount of the dispersant used depends on the type, but is 0.1 part by weight or more and 3.0 parts by weight or less with respect to 100 parts by weight of water as a poorly water-soluble inorganic salt, and 30 ppm as an anionic surfactant or water-soluble polymer. More than 500 ppm is preferable.

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

As the polymerization initiator used in the first-stage polymerization, a radical-generating polymerization initiator generally used for producing a thermoplastic polymer can be used, and typical examples thereof are benzoyl peroxide and lauroyl. Peroxide, t-butylperoxybenzoate, isopropyl-t-butylperoxycarbonate, butyl perbenzoate, t-butylperoxy-2-ethylhexanoate, t-butylperpivalate, t-butylperoxyisopropyl 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, t-butylperoxy-2-ethylhexyl monocarbonate, and other organic radicals, azobisisobutyronitrile, azobisdimethyl Examples include azo compounds such as valeronitrile. These polymerization initiators may be used alone or in combination of two or more.

Examples of the foaming agent include propane, isobutane, normal butane, isopentane, normal pentane, neopentane and other aliphatic hydrocarbons having 3 or more and 5 or less carbon atoms, for example, ozone destruction of difluoroethane, tetrafluoroethane and the like. Examples thereof include volatile foaming agents such as hydrocarbons having a coefficient of zero. These foaming agents may be used in combination. The amount used is preferably 4 parts by weight or more and 10 parts by weight or less, and more preferably 5 parts by weight or more and 9 parts by weight or less 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 foaming 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 adjusting agent, 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 examples thereof include 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 plasticizing agent include high boiling point plasticizing agents 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, liquid paraffin, and organic hydrocarbons such as cyclohexane.

Examples of the bubble adjusting agent include aliphatic bisamides such as methylene bisstearic acid amide and ethylene bisstearate amide, and polyethylene wax.

Specific examples of the external preparation include fatty acid triglycerides such as triglyceride laurate, triglyceride stearate, triglyceride linoleic acid, and triglyceride hydroxystearate, diglyceride laurate, diglyceride stearate, and diglyceride linoleic acid, and lauric acid. Fatty acid monoglyceride such as monoglyceride, monoglyceride stearate, monoglyceride linoleic acid, vegetable oil such as castor oil, soybean oil, olive oil, fatty acid metal salt 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, nonionic surfactants such as polyoxyethylene oleate, etc. Can be mentioned. These external additives and attachments may be used alone or in combination of two or more. Of these, triglyceride stearate and castor oil are preferable because they promote the fusion of foams. Further, 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 drying, regardless of the coating method. A preferred coating method is a method of coating by attaching after drying and mixing and stirring.

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

Specific examples of the flame retardant include halogenated aliphatic hydrocarbon compounds such as hexabromocyclododecane, tetrabromobutane, and 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 copolymer , Brobroinated random styrene / butadiene copolymer, brominated butadiene / vinyl aromatic hydrocarbon copolymer such as brominated styrene / butadiene graph and copolymer (for example, EMERALD3000 manufactured by Chemtura, and Special Table 2009-516019). Disclosed in the Gazette) and the like. These flame retardants may be used alone or in combination of two or more.

As a specific example of the flame retardant aid, for example, an initiator such as cumene hydroperoxide, dicumyl peroxide, t-butyl hydroperoxide, 2,3-dimethyl-2,3-diphenylbutane may be used. ..

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

Further, the effervescent styrene-based prefoamed particles can be molded by a general in-mold molding method to obtain a foamed molded product. Specifically, it is filled in a mold that can be closed but cannot be closed, and heat-fused with steam to obtain a styrene-based foam molded product.

The styrene-based 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 thereto.

<GPC measurement>
0.02 g of the foamable polystyrene-based resin particles were dissolved in 20 ml of tetrahydrofuran (hereinafter, may be abbreviated as "THF") with respect to the obtained foamable polystyrene-based resin particles, and then the gel component was filtered. Next, GPC measurement was performed on only the components soluble in THF using a gel permeation chromatograph (GPC) under the following conditions, and the GPC measurement chart, weight average molecular weight (Mw), and number 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: High-speed GPC device HLC-8220 manufactured by Tosoh Corporation
Column used: Tosoh, 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 method for residual styrene>
Effervescent polystyrene resin particles are dissolved in methylene chloride (internal standard cyclopentanol), and the amount of residual styrene (ppm) contained in the effervescent styrene resin particles is determined by using gas chromatography (GC) under the following conditions. Quantified.
Measuring device: Gas chromatography GC-2014 manufactured by Shimadzu Corporation
Column: Capillary column (RL Science Rtx-1)
Column temperature conditions: 50 → 80 ° C. (3 ° C./min), then 80 → 180 ° C. temperature rise (10 ° C./min),
Carrier gas: helium.

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

<Manufacturing of preliminary foamed particles>
Effervescent polystyrene-based resin particles classified into a predetermined particle size by a sieve are blown into a prefoaming machine "Daikai Kogyo, BHP" under the condition of a vapor pressure of 0.09 to 0.12 MPa to a bulk magnification of 45 times. After that, the particles were left at room temperature for 1 day to obtain pre-foamed particles having a bulk ratio of 45 times.

<Manufacturing of foam molding>
The obtained styrene-based prefoamed particles were blown into the mold using a molding machine "Daisen, KR-57" and molded in the mold at a vapor pressure of 0.10 MPa to form a flat plate having a thickness of 50 mm and a length of 400 mm and a width of 350 mm. Foam molded article was obtained.

<Surface property of molded product>
The state of the surface of the foam molded product was evaluated by visual observation. The larger the value, the more beautiful the surface condition with less gaps between the particles, and a score of 3 or more expressed on a scale of 5 was considered acceptable.

5: No gaps are found 4: There are some gaps, but I can hardly understand them 3: There are some gaps, but they are acceptable as a whole 2: The 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 foam molded product using a vertical slicer (manufactured by Sakura Engineering).

The test piece was allowed to stand still in a constant temperature and humidity chamber having a temperature of 23 ° C. and a humidity of 50% for 12 hours. Then, under the same environment, the test piece was rubbed against the iron plate 10 times with a surface tester HEIDON Type: 14FW (manufactured by Shinto Kagaku Co., Ltd.) under the conditions of a load of 200 g, a reciprocating distance of 50 mm, and a sliding speed of 3000 mm / min. The average value of the coefficient of static friction for each rubbing was calculated.

<Measurement of rubbing sound>
A rectangular parallelepiped test piece of a double-sided skin having a length of 300 mm, a width of 60 mm, and a thickness of 25 mm was cut out from the obtained foam molded product using a vertical slicer (manufactured by Sakura Engineering). Further, a test piece of a triangular prism having a 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 allowed to stand in a constant temperature and humidity chamber having a temperature of 23 ° C. and a humidity of 50% for 12 hours. Then, under the same environment, a triangular prism test piece was placed on the rectangular parallelepiped test piece so that the corners touched, and a load of 2000 g was placed on the triangular pyramid test piece. In that state, the test piece was reciprocated 10 times in a section having a width of 50 mm at a speed of 6000 mm / min.

The rubbing sound generated at that time was measured with a sound collecting microphone over a wide range and sound pressure. The highest sound pressure in the range of 5,000 or more and 20,000 Hz or less, which humans feel uncomfortable, was 40 dB or less.

(Example 1)
<Manufacturing of polystyrene resin seed particles>
In a reactor equipped with a stirrer, 100 parts by weight of pure water, 0.4 parts by weight of tricalcium phosphate, 0.01 parts by weight of sodium dodecylbenzenesulfonate, 0.5 parts by weight of sodium chloride, and polyethylene wax as a nucleating agent 0. After adding 07 parts by weight and stirring to form an aqueous suspension, 0.2 parts by weight of benzoyl peroxide and 1,1-bis (t-butylperoxy) were added to 100 parts by weight of the styrene monomer as a polymerization initiator. ) Dissolve 0.2 parts by weight of cyclohexane, add to the reactor, heat to 98 ° C., polymerize for 4.5 hours, cool, take out the contents, dehydrate and dry, and sieve. To obtain polystyrene-based resin seed particles having a particle diameter of 0.4 to 0.5 mm.

<Manufacturing of foamable polystyrene resin particles>
In a 6L autoclave attached to the stirrer, 167 parts by weight of pure water, 0.82 parts by weight of tricalcium phosphate, 0.022 parts by weight of α-olefin sulphonate, 0.2 parts by weight of sodium chloride, t-butylperoxy. After charging 0.04 parts by weight of -2-ethylhexyl monocarbonate (10-hour half-life temperature 99 ° C.) and 20 parts by weight of styrene-based resin seed particles having a particle size of 0.4 to 0.5 mm, stirring was started. Subsequently, after the temperature was raised to 90 ° C., 0.22 parts by weight of a benzoyl peroxide 30% solution was charged in a reactor for 5 hours and 78.5 parts by weight of a styrene monomer was charged in a reactor for polymerization. did. At this time, when the addition of the styrene monomer was completed (5 hours after the temperature was raised to 90 ° C.), the methacryloyl-containing polysiloxane (methacryloyloxypropyldimethoxymethylsilane content: 2.5% by weight, molecular weight: 200,000) was 1.5. 0.075 parts by weight and 0.075 parts by weight of di-t-butylperoxyhexahydroterephthalate were charged over 1 hour and 30 minutes and maintained at 90 ° C. for 30 minutes. Then, the temperature was raised to 120 ° C. and held for 1 hour, then cooled to 98 ° C. to charge 1.0 part by weight of cyclohexane, 6.5 parts by weight of normal rich butane (70% normal butane, 30% isobutane), and 110 parts by weight. 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 effervescent polystyrene resin particles having a particle size of 0.6 to 1.15 mm.

The obtained effervescent polystyrene-based resin particles are sieved to obtain effervescent polystyrene-based resin particles having a particle diameter of 0.5 to 1.0 mm, and further, using a pressurized pre-foaming machine "BHP-300 (manufactured by Daikai Kogyo)" Pre-foamed particles were obtained with a bulk ratio of 45 times. After curing the obtained preliminary foamed particles at room temperature for one day, a foamed molded product was obtained in a mold having a size of 300 × 450 × 50 (t) mm using a molding machine “KR-57 (manufactured by Daisen)”. , The surface properties of the molded product, the coefficient of static friction, and the rubbing noise were evaluated. The evaluation results are shown in Table 1.

(Example 2)
Same as in Example 1 except that 78 parts by weight of a styrene-based monomer, 2.0 parts by weight of polysiloxane containing methacryloyl, 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)
Examples except that 77.5 parts by weight of a styrene-based monomer, 2.5 parts by weight of a polysiloxane containing methacryloyl, and 0.125 parts by weight of di-t-butylperoxyhexahydroterephthalate were charged over 2.5 hours. The same procedure as in 1 was performed. The evaluation results are shown in Table 1.

(Example 4)
The same procedure as in Example 1 was carried out except that 77 parts by weight of a styrene-based monomer, 3 parts by weight of a 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)
96 parts by weight of water, 0.17 parts by weight of tricalcium phosphate, 0.048 parts by weight of sodium α-olefin sulphonate in a 6 L autoclave with a stirrer, brominated butadiene-styrene copolymer as a flame retardant (Cemtura "EMERALD 3000" Bromine content 64%) 1.2 parts by weight, 0.2 parts by weight of dicumyl peroxide as a flame retardant, 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, the temperature was raised to 98 ° C., and polymerization was carried out 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 were applied over 2 hours. Was added, and the mixture was further polymerized for 30 minutes. Further, 1.0 part by weight of cyclohexane and 6.5 parts by weight of normal rich butane (70% normal butane, 30% isobutane) were charged, the temperature was raised to 120 ° C., and the foaming agent was impregnated and polymerized for 4 hours. Then, after cooling to 40 ° C., it was washed, dehydrated, and dried to obtain foamable polystyrene resin particles.

The obtained effervescent polystyrene-based resin particles are sieved to obtain effervescent polystyrene-based resin particles having a particle diameter of 0.5 to 1.0 mm, and further, using a pressurized pre-foaming machine "BHP-300 (manufactured by Daikai Kogyo)" Pre-foamed particles were obtained with a bulk ratio of 45 times. After curing the obtained preliminary foamed particles at room temperature for one day, a foamed molded product was obtained in a mold having a size of 300 × 450 × 50 (t) mm using a molding machine “KR-57 (manufactured by Daisen)”. , The surface properties of the molded product, the coefficient of static friction, and the rubbing noise were evaluated. The evaluation results are shown in Table 1.

(Example 6)
Instead of 78.5 parts by weight of the styrene-based monomer, 73 parts by weight of the styrene monomer and 5 parts by weight of butyl acrylate were mixed in advance, and a total of 80 parts by weight of the monomer was added over 5 hours and 30 minutes. Then, 2.0 parts by weight of polysiloxane containing methacryloyl and 0.1 part by weight of dit-butylperoxyhexahydroterephthalate were charged over 2 hours, and the same procedure as in Example 1 was carried out. 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-based monomer was changed to 80 parts by weight and the methacryloyl-containing polysiloxane and di-t-butylperoxyhexahydroterephthalate were not used. The evaluation results are shown in Table 1.

(Comparative Example 2)
The same procedure as in Example 1 was carried out except that 79 parts by weight of a styrene-based monomer, 1 part by weight of a methacryloyl-containing polysiloxane and 0.05 parts 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 styrene-based monomer, 3.5 parts by weight of a polysiloxane containing methacryloyl, 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 parts by weight of both-terminal methacrylic dimethylpolysiloxane (X-22-164B (viscosity 55 mm ² / s (25 ° C.)) and 0.15 parts by weight of di-t-butylperoxyhexahydroterephthalate for 3.0 hours It was carried out in the same manner as in Example 1 except that it was charged in a sprinkled manner. The evaluation results are shown in Table 1.

(Comparative Example 5)
Two parts by weight of one-ended methacrylic dimethylpolysiloxane (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 the above, the same procedure as in Example 1 was carried out.

Claims (7)

The monomer composition is 96.7 parts by weight or more and 98.8 parts by weight or less of the styrene-based monomer, and 1.2 parts by weight or more and 3.3 parts by weight or less of the polysiloxane-containing macromonomer monomer (styrene-based single amount). The total amount of the body 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 or more and 250 nm or less by copolymerizing. Foamable polystyrene-based resin particles characterized in that the main component of the surface layer portion of the above is polysiloxane. The effervescent polystyrene-based resin particles according to claim 1, wherein the functional group is a methacryloyl group. The foamable polystyrene-based resin particles according to claim 1 or 2, wherein the weight average molecular weight determined by using GPC, which is a component soluble in THF, is 200,000 or more and 400,000 or less. The foamable polystyrene-based resin particles according to any one of claims 1 to 3, wherein the amount of residual monomer monomer is 1000 ppm or less. The effervescent polystyrene according to any one of claims 1 to 4, wherein the weight average molecular weight determined by using GPC of polysiloxane, which is the main chain of the polysiloxane-containing macromonomer, is 20,000 or more and 500,000 or less. System resin particles. The polystyrene-based pre-expanded particles, which are obtained by pre-foaming the effervescent polystyrene-based resin particles according to any one of claims 1 to 5. A foamed molded product obtained by molding the polystyrene-based prefoamed particles according to claim 6.