JP6971743B2 - Method for manufacturing foamable styrene resin particles - Google Patents

Description

The present invention relates to a method for producing foamable styrene resin particles used for in-mold foam molding. More specifically, the present invention relates to a method for producing effervescent styrene resin particles capable of reducing the content of volatile organic components.

Generally, as a method for producing effervescent styrene-based resin particles, a method of polymerizing a commercially available styrene monomer (hereinafter, may be simply referred to as styrene) in an aqueous suspension system to produce resin particles and then impregnating with a foaming agent. Alternatively, a method of melt-kneading a commercially available styrene-based resin with an extruder to produce resin particles and then impregnating with a foaming agent is known. A foam obtained by in-mold foam molding of foamable styrene resin particles produced by such a method (hereinafter, also referred to as a foam molded product) is a lightweight material and is an excellent material as a heat insulating material. Therefore, it has been widely used as a heat insulating material for walls, floors, roofs, etc. of buildings, a core material for tatami mats, an automobile member, and the like.

By the way, the effervescent styrene resin particles generally contain volatile organic components such as ethylbenzene and styrene monomer (hereinafter, may be referred to as VOC). These organic volatile components are discharged into the atmosphere when the pre-foamed particles of the foamable styrene resin particles are produced, and the odor may lead to deterioration of the working environment. Further, when the volatile organic component remains in the foamed molded product obtained by in-mold foam molding, the volatile organic component is discharged into the atmosphere to cure and store the foamed molded product. Odor may be generated in the warehouse inside.
In recent years, with the progress of high airtightness and high heat insulation of houses and automobiles, indoor air pollution due to various volatile organic components, that is, sick house syndrome has become an important problem. In order to solve this sick house syndrome, there is a movement to regulate the amount of organic components in the air in the room. Therefore, it is desirable to reduce the amount of volatile organic components released from the effervescent styrene resin particles as much as possible. Therefore, foamable styrene resin particles having a small amount of VOC are desired.

Here, the main volatile organic components in the effervescent styrene resin particles are styrene and ethylbenzene. Styrene can be reduced by selecting the polymerization conditions and the polymerization initiator in the polymerization reaction contained in the process of producing the effervescent styrene resin particles, but ethylbenzene does not contribute to the polymerization reaction, so that it is contained in the styrene resin. The amount of ethylbenzene remains as it is in the effervescent styrene resin particles. As described above, the amount of ethylbenzene in the effervescent styrene resin particles tends to depend on the amount of ethylbenzene in the styrene resin, and the amount of VOC components (particularly, the amount of styrene) is reduced by the polymerization method. It is difficult to obtain particles.

Further, as a method for producing foamable styrene resin particles using a styrene resin, for example, in Patent Document 1, a styrene resin is melt-kneaded with an extruder, extruded through a die having small holes, and then cut with a cutter. Thus, a production method obtained by suspending the styrene-based resin particles in water after obtaining the styrene-based resin particles and containing a foaming agent is disclosed. Further, in Patent Document 3, a foaming agent is applied to the styrene-based resin particles obtained by absorbing and polymerizing a styrene-based monomer into short-strand-shaped seed particles produced by melt-kneading the styrene-based resin with an extruder. A method for producing foamable styrene resin particles to be impregnated is disclosed. However, the method of Patent Document 1 cannot reduce the VOC contained in the styrene-based resin used, and the method of Patent Document 3 uses polymerization to polymerize the styrene-based resin and ethylbenzene in the styrene-based monomer. Low VOC has not been achieved without being consumed.

As a method for reducing the amount of VOC, for example, in Patent Documents 2 and 4, a styrene resin is melt-kneaded with water by an extruder, degassed and sucked, and then a foaming agent is press-fitted to reduce the VOC of the polystyrene-based extrusion foam insulation. Although a method for producing a material is disclosed, there is no description regarding a method for producing foamable styrene resin particles.
Japanese Unexamined Patent Publication No. 2014-80514 Japanese Unexamined Patent Publication No. 2002-225104 Japanese Unexamined Patent Publication No. 2006-036993 WO2002 / 022723

In view of the above circumstances, it is an object of the present invention to provide a method for producing effervescent styrene resin particles capable of reducing the content of volatile organic components.

As a result of diligent studies, the present inventors have completed the present invention. That is, the present invention is as follows.
(1) 0.01 to 5 parts by weight of water and 0.05 to 0.6 parts by weight of a heat stabilizer are melt-kneaded with 100 parts by weight of a styrene resin in an extruder, and then volatile organic components are put into the extruder. To produce styrene resin particles by suction treatment under the condition of vacuum degree of -0.08 MPaG or less and cylinder temperature of the molten part of 200 ° C to 250 ° C, extruding through a die having small holes, and then cutting with a cutter. A foamable styrene resin comprising a step of suspending the styrene resin particles obtained in the above step in water and impregnating the styrene resin particles with a foaming agent at a temperature of 100 ° C to 120 ° C. How to make particles.
(2) The foamable styrene resin particles of (1), wherein the amount of volatile organic components (total amount of styrene monomer and ethylbenzene) of the styrene resin particles produced in the step of producing the styrene resin particles is less than 200 ppm. Manufacturing method.
(3) The foamability according to (1) or (2), wherein 0.5 parts by weight or more and 3 parts by weight of water are added to 100 parts by weight of the styrene resin in the step of producing the styrene resin particles. A method for producing styrene-based resin particles.
(4) The heat stabilizer is at least one compound selected from the group consisting of hindered amine compounds, phosphorus compounds and epoxy compounds (1) to (3).
). The method for producing effervescent styrene resin particles according to any one of.
(5) The heat stabilizer is a phosphorus-based stabilizer and a hindered amine-based stabilizer. The phosphorus-based stabilizer is 0.025 to 0.3 parts by weight and the hindered amine-based stabilizer is 100 parts by weight based on 100 parts by weight of the styrene resin. The method for producing effervescent styrene resin particles according to any one of (1) to (4), which comprises adding 0.025 to 0.3 parts by weight of the agent.
(6) Any of (1) to (5), wherein the foaming agent is at least one compound selected from the group consisting of normal butane, isobutane, normal pentane, isopentane, cyclopentane and neopentane. The method for producing foamable styrene resin particles according to.
(7) A step of heating the effervescent styrene resin particles produced by the production method according to any one of (1) to (6) and pre-foaming them to obtain pre-foamed particles, and a step of preliminarily obtained in the above step. A method for manufacturing a foamed molded product, comprising a step of filling a foamed particle into a molding cavity and foaming and molding in a mold.

According to the present invention, foamable styrene resin particles having a reduced content of volatile organic components can be produced.

The foamable styrene resin particles of the present invention are obtained by melt-kneading 0.01 to 5 parts by weight of water and 0.05 to 0.6 parts by weight of a heat stabilizer with an extruder against 100 parts by weight of the styrene resin. The volatile organic component was sucked from the inside of the extruder under the conditions of a vacuum degree of -0.08 MPaG or less and a cylinder temperature of 200 ° C. to 250 ° C. of the molten part, extruded through a die having small holes, and then cut with a cutter. A method for producing foamable styrene resin particles, which comprises suspending styrene resin particles in water and impregnating the styrene resin particles with a foaming agent at a temperature of 100 ° C. to 120 ° C. be.

Here, the main volatile organic components in the effervescent styrene resin particles are styrene and ethylbenzene. Styrene can be reduced by selecting the polymerization conditions and the polymerization initiator in the polymerization reaction contained in the process of producing the effervescent styrene resin particles, but ethylbenzene does not contribute to the polymerization reaction, so that it is contained in the styrene resin. The amount of ethylbenzene remains as it is in the effervescent styrene resin particles. As described above, the amount of ethylbenzene in the effervescent styrene resin particles tends to depend on the amount of ethylbenzene in the styrene resin, and the amount of VOC components (particularly, the amount of styrene) is reduced by the polymerization method. It is difficult to obtain particles. Further, in many commercially available styrene-based resins, the total amount of ethylbenzene and styrene exceeds 200 ppm, and it is difficult to reduce ethylbenzene and styrene to 200 ppm or less.

As described above, the present situation is that effervescent styrene resin particles having an amount of volatile organic components of ethylbenzene and styrene of 200 ppm or less have not been obtained.
The styrene-based resin used in the present invention is not only a styrene homopolymer (polystyrene homopolymer), but also other monomers copolymerizable with styrene or derivatives thereof are copolymerized as long as the effects of the present invention are not impaired. May be. Generally, the amount of VOC component (styrene + ethylbenzene) in these styrene-based resins exceeds 200 ppm.

Examples of other monomers copolymerizable with styrene or derivatives thereof include methylstyrene, dimethylstyrene, ethylstyrene, diethylstyrene, isopropylstyrene, bromostyrene, dibromostyrene, tribromostyrene, chlorostyrene, dichlorostyrene, and the like. Styrene derivatives such as trichlorostyrene; polyfunctional vinyl compounds such as divinylbenzene; (meth) acrylic acid ester compounds such as methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, butyl acrylate, butyl methacrylate; (Meta) Vinyl cyanide compounds such as acrylonitrile; Diene compounds such as budadiene or derivatives thereof; unsaturated carboxylic acid anhydrides such as maleic anhydride and itaconic anhydride; N-methylmaleimide, N-butylmaleimide, N-cyclohexyl Examples thereof include N-alkyl substituted maleimide compounds such as maleimide, N-phenylmaleimide, N-4-diphenylmaleimide, N-2-chlorophenylmaleimide, N-4-bromophenylmaleimide and N-1-naphthylmaleimide. These may be used alone or in combination of two or more.

The styrene-based resin used in the present invention is not limited to the styrene homopolymer and / or a copolymer with another monomer copolymerizable with styrene or a derivative thereof, and does not impair the effects of the present invention. In the range, it may be a homopolymer or a blend of the other monomer or derivative with a homopolymer or a copolymer, and for example, diene-based rubber-reinforced polystyrene, acrylic-based rubber-reinforced polystyrene, polyphenylene ether-based resin, and the like may be used. It can also be blended.

Among the styrene-based resins used in the present invention, it is relatively inexpensive, can be foam-molded with low-pressure steam or the like without using a special method, and has an excellent balance of heat insulating properties, flame retardancy, and cushioning properties. Polystyrene homopolymers, styrene-acrylonitrile copolymers and styrene-butyl acrylate copolymers are preferred.

By kneading the water used in the present invention with the styrene-based resin melted in the extruder, the organic volatile components can be efficiently sucked and removed from the extruder. The function of water is that by mixing VOC components (ethylbenzene, styrene) with water, it has a minimum co-boiling point and boils at a temperature lower than the boiling point of water (100 ° C). It can be removed efficiently.

The amount of water added in the present invention is preferably 0.01 parts by weight or more and 5 parts by weight or less, and more preferably 0.5 parts by weight or more and 3 parts by weight or less with respect to 100 parts by weight of the styrene resin. preferable. When the amount of water added is less than 0.01 parts by weight, the effect of azeotrope is small and the amount of VOC component cannot be reduced. The size becomes large, the strands extruded through the die having small holes become unstable, the strands are frequently broken, and the weight variation of the resin particles becomes large.

The heat stabilizer used in the present invention (hereinafter, also referred to as a stabilizer) is a phenol-based antioxidant, a phosphorus-based stabilizer, a nitrogen-based stabilizer, a sulfur-based stabilizer, a lactone-based stabilizer, and a benzotriazole. System stabilizers, hindered amine system stabilizers, etc.

Specific stabilizers include, for example, phosphorus such as tris (2,4-di-t-butylphenyl) phosphite and bis (2,6-t-butyl-4-methylphenyl) -pentaerythritol diphosphite. System stabilizer,
Bis decaneate (2,2,6,6-tetramethyl-4-piperidinyl), bis decaneate (1,2,2,6,6-pentamethyl-4-piperidinyl), bisdecandiate (2,2) 2,6,6-Tetramethyl-1 (octyloxy-4-piperidinyl), tetrakis (2,2,6,6-tetramethyl-4-piperidyl) -1,2,3,4-butanetetracarboxylate, etc. 4-Hydroxy-2,2,6,6-tetramethylpiperidine, 4-hydroxy-1,2,2,6,6-pentamethylpiperidine, or 4-hydroxy-1-octyloxy-2,2,6 , A hindered amine-based stabilizer that is an aliphatic or aromatic carboxylic acid ester of 6-tetramethylpyridine,
Ethylene bis (oxyethylene) bis [3- (5-tert-butyl-4-hydroxy-m-tolyl) propionate], pentaerythritol tetrakis [3- (3,5-di-t-butyl-4-hydroxyphenyl) Propionate] and other phenolic stabilizers.

These may be used alone or in combination of two or more. Among these, in particular, phosphorus-based stabilizers such as tris (2,4-di-t-butylphenyl) phosphite and bis (2,6-t-butyl-4-methylphenyl) -pentaerythritol diphosphite. And bis decanoate (2,2,6,6-tetramethyl-4-piperidinyl), bis decanoate (1,2,2,6,6-pentamethyl-4-piperidinyl), bis decanoate (1,2,2,6,6-pentamethyl-4-piperidinyl) 2,2,6,6-tetramethyl-1 (octyloxy-4-piperidinyl), tetrakis (2,2,6,6-tetramethyl-4-piperidyl) -1,2,3,4-butanetetracarboxyl It is preferable to use a hindered amine-based stabilizer such as lat, because it does not deteriorate the flame retardant performance of the foam and improves the thermal stability of the foam.

The content of the stabilizer in the present invention is preferably 0.025 to 0.3 parts by weight for the phosphorus-based stabilizer and 0. 025 to 0.3 parts by weight is preferable, and when used in combination, the total amount of stabilizer is preferably 0.05 parts by weight to 0.6 parts by weight.

If the total amount of the heat stabilizer is less than 0.05 parts by weight, the styrene resin is decomposed in the extruder and the amount of styrene increases, which is not preferable. If the amount of the heat stabilizer exceeds 0.6 parts by weight, the styrene resin is decomposed. Decomposition of the resin can be suppressed, but in addition to the high cost, the strength of the foamed molded product tends to be weakened due to the plasticizing effect of the polystyrene-based resin by the stabilizer.

In the present invention, additives such as flame retardants, processing aids, antistatic agents, and colorants such as pigments can be contained, if necessary. In particular, flame retardancy is an important property in the building materials and automobile markets.

Specific examples of flame retardant agents include halogenated alicyclic compounds such as hexabromocyclododecane, tetrabromocyclooctane, chloropentabromocyclohexane; hexabromobenzene, pentabromotoluene, ethylenebispentabromodiphenyl, decabromodiphenyl ether, etc. Halogenization of 2,3-dibromopropylpentabromophenyl ether, bis (2,4,6-tribromophenoxy) ethane, tetrabromobisphenol phthalic acid, octabromotrimethylphenyl indane, pentabromobenzyl acrylate, tribromophenylallyl ether, etc. Aroma compounds or derivatives thereof; Tetrabromobisphenol-A, Tetrabromobisphenol-S, Tetrabromobisphenol-F, Tetrabromobisphenol-A-bis (2,3-dibromopropyl ether), Tetrabromobisphenol-S-bis ( 2,3-Dibromopropyl ether), Tetrabromobisphenol-F-bis (2,3-dibromopropyl ether), Tetrabromobisphenol-A-bis (2,3-dibromo-2-methylpropyl ether), Tetrabromobisphenol -S-bis (2,3-dibromo-2-methylpropyl ether), tetrabromobisphenol-F-bis (2,3-dibromo-2-methylpropyl ether), tetrabromobisphenol-A-diallyl ether, tetrabromo Brominated bisphenols and derivatives thereof such as bisphenol-S-diallyl ether, tetrabromobisphenol-F-diallyl ether, brominated styrene, brominated butadiene-vinyl aromatic copolymer, brominated novolak resin allyl ether, brominated. Examples thereof include brominated polymers such as poly (1,3-cycloalkaziene) and brominated poly (4-vinylphenol allyl ether). These substances may be used alone or as a mixture of two or more kinds.

Specific examples of the processing aid include sodium stearate, magnesium stearate, calcium stearate, zinc stearate, barium stearate, liquid paraffin and the like.

The method for producing foamable styrene resin particles of the present invention is as follows: (1) Using an extruder equipped with a suction degassing port, the styrene resin and the above-mentioned compounding agent are melt-kneaded and then cut into particles. The styrene-based resin particles are impregnated with a foaming agent at a temperature of 100 ° C. to 120 ° C. by suspending the resin particles obtained in the extrusion step and (2) the extrusion step in water. It can be distinguished from the foaming agent impregnation step of obtaining the sex styrene resin particles.

(1) Extrusion Step Examples of the extruder having a suction degassing port used in the manufacturing method of the present invention include a single-screw extruder and a twin-screw extruder.
The cylinder temperature at the melted portion of the extruder in the manufacturing method of the present invention may be any temperature as long as the styrene resin melts, and is preferably 200 ° C. or higher and 250 ° C. or lower. It is preferable that the residence time in the extruder from the supply of the styrene resin and various formulations to the end of melt kneading is 7 minutes or less. If the temperature is lower than 200 ° C., the load on the extruder may become large and the extrusion may become unstable, or the dispersibility of the material to be added may deteriorate. On the other hand, if the temperature exceeds 250 ° C. and / or if the residence time in the extruder until the end of fusion and kneading is longer than 7 minutes, the styrene resin itself may be decomposed or the flame retardant itself may be decomposed.

It is preferable to add water by using a press-fitting pump from a portion on the die side of the cylinder after the raw material feed portion of the extruder having a single-screw or twin-screw screw because a predetermined amount is added. When a resin composition obtained by premixing styrene resin with water in a blender is put into an extruder, the raw material supply of the extruder becomes unstable, strand breakage occurs, and styrene resin particles having the same grain weight are obtained. It tends not to be.

It is preferable that the suction / degassing port is provided at a position on the die side of the water press-fitting portion and at least one is provided in the extruder. Further, it is preferable to install a suction degassing port at a place where the styrene resin is melt-kneaded. If a suction port is provided in a place where the mixture is not melt-kneaded, the powder of the compounding agent may be scattered from the suction / degassing port.

The lower the degree of vacuum for suction and degassing, the more the VOC component can be removed, but it is preferably −0.08 MPaG or less, and the VOC component is efficiently sucked and removed. If the lower limit value is described, it is −1.0 MPaG. If it is lower than −1.0 MPaG, it is not preferable from the viewpoint of device load. That is, the range from −1.0 MPa to −0.08 MPaG is preferable. If it is higher than −0.08 MPaG, the suction removal amount of the VOC component amount becomes small.

In the manufacturing method of the present invention, the molten resin melt-kneaded in the extruder is cooled in a water tank having a temperature of 10 ° C. or higher and 40 ° C. or lower, and the strands are cut by a rotary cutter. Then, styrene-based resin particles having a grain weight of 0.3 mg to 1.0 mg are obtained. The diameter of the small holes in the die is preferably 0.2 mm or more and 1.5 mm or less, and more preferably 0.3 mm or more and 1.0 mm or less. Further, a method of granulating styrene resin particles such as underwater cut may be used.

(2) Foaming agent impregnation step Using a pressure-resistant container with a stirring blade, the styrene-based resin particles obtained in the extrusion step are suspended in water together with a dispersant. Examples of the dispersant include commonly used dispersants, for example, poorly water-soluble inorganic salts such as calcium phosphate, hydroxyapatite, and magnesium pyrophosphate. When these poorly water-soluble inorganic salts are used, it is effective to use anionic surfactants such as α-olefin sulphonic acid sodium and dodecylbenzene sulphonic acid sodium in combination because the dispersion stability is increased.

The foaming agent is then added to the suspension. As the foaming agent used in the present invention, at least one selected from the group consisting of propane, isobutane, normal butane, isopentane, normal pentane, and neopentane is used. The amount used is preferably 2 parts by weight or more and 10 parts by weight or less, and more preferably 4 parts by weight or more and 8 parts by weight or less with respect to 100 parts by weight of the styrene resin particles.

After adding the foaming agent, the temperature in the polymerization system is raised to 100 ° C. or higher and 120 ° C. or lower, preferably 110 ° C. or higher and 120 ° C. or lower, and the foaming agent is impregnated into the resin particles for a certain period of time. When the impregnation temperature is less than 100 ° C., the degree of impregnation of the foaming agent into the resin particles is poor, the cell structure of the foamed particles becomes non-uniform, and the appearance of the foamed molded product obtained is impaired. On the other hand, if the temperature exceeds 120 ° C., the impregnation of the foaming agent is improved, but the internal pressure of the polymerizer becomes high, and a polymerizer specification having a pressure resistance of heavy equipment may be required. After the predetermined time of impregnation with the foaming agent is completed, the polymerization temperature is cooled and dried to obtain effervescent styrene resin particles.

The upper limit of the amount of VOC (total of styrene and ethylbenzene) in the effervescent styrene resin particles is 200 ppm or less. The lower limit is practically difficult to be 0 ppm, so if it is intentionally displayed, it is 1 ppm or more.

The foamable styrene resin particles of the present invention 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 prefoamed particles can be molded by a general in-mold molding method to form 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 foam molded product.
Since the amount of VOC in the foamed molded product does not exceed the amount of VOC in the foamable styrene resin particles, by using the foamable styrene resin particles having a VOC content of 200 ppm or less, a low VOC of 200 ppm or less is used. It is possible to manufacture foamed molded bodies such as building materials and automobile interior materials, which are required for the above. However, if the foamed molded product is stored in combination with the foamed molded product having a large amount of VOC, the emitted VOC may be absorbed into the foamed molded product and may exceed 200 ppm, so caution is required. be.

Hereinafter, the present invention will be specifically described with reference to Examples and Comparative Examples, but the present invention is not limited thereto. The examples and comparative examples were evaluated by the following methods.

(Measurement of styrene and ethylbenzene)
The sample was dissolved in methylene chloride (internal standard cyclopentanol), gas chromatography GC-2014 manufactured by Shimadzu Corporation (capillary column: Rtx-1, manufactured by GL Science, column temperature condition: 50 → 80 ° C. (3 ° C./). After min), the amount of styrene-based resin particles, foamable styrene-based resin particles, and the amount of styrene and ethylbenzene contained in the foamed molded product (min), using a temperature rise of 80 → 180 ° C. (10 ° C./min), carrier gas: helium) (min). ppm) was quantified.

(Extrusion stability)
In the extrusion process, those in which the strands obtained through the die were stably taken out without pressure fluctuation during extrusion were marked with ◯, and those not were marked with x.

(Vaporized content)
The effervescent styrene resin particles were heat-treated in an oven at 150 ° C. for 30 minutes, and the weight loss was measured.

(Cell uniformity of foamed particles)
The foamed particles were cut with a cutter, and the cell structures in the surface layer and the center of the foamed particles were observed. If the cell chord lengths of the surface layer and the center are almost the same, they are regarded as uniform and marked with ◯, and if the cell chord lengths are different, they are regarded as non-uniform and marked with x.

In the examples and comparative examples, the following raw materials were used.
<Styrene resin>
(A1) Styrene-based resin [manufactured by PS Japan Corporation, G9401]
(A2) Styrene-based resin [manufactured by PS Japan Corporation, G0002]
(A3) Styrene resin [manufactured by Toyo Styrene Co., Ltd., HRM52N]
The amount of VOC in the styrene resin is shown in Table 1.

<Heat stabilizer>
(B1) Bis (2,6-t-butyl-4-methylphenyl) -pentaerythritol diphosphite [manufactured by ADEKA Corporation, ADEKA STUB PEP-36]
(B2) Tetrakis (2,2,6,6-tetramethyl-4-piperidyl) -1,2,3,4-butanetetracarboxylate [Adeka Stab LA-57, manufactured by ADEKA Corporation]
<Flame retardant>
(C1) Tetrabromobisphenol A-bis (2,3-dibromo-2-methylpropyl) ether [Pyroguard SR-130, manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.]
<Effervescent agent>
(D1) Butane [Mixed butane with normal / iso = 70/30 ratio, manufactured by Iwatani Corp.]

(Example 1)
[Preparation of styrene resin particles]
To 100 parts by weight of the styrene resin (A1), 0.15 parts by weight of the heat stabilizer (B1) and 4 parts by weight of the flame retardant (C1) are added to the blender and blended for 10 minutes to form a resin composition. Got The obtained resin composition is supplied to a twin-screw extruder (TEM-26SX, manufactured by Toshiba Corporation), melt-kneaded in the extruder at a cylinder temperature of the melting part at 240 ° C., and water is pumped by a press-fitting pump. 0.5 part by weight was press-fitted and degassed from the degassing suction port using a vacuum pump (SW-25S, manufactured by Shinko Seiki Co., Ltd.) with a vacuum degree of −0.09 MPaG. A strand-shaped resin extruded at a discharge rate of 200 kg / hour through a die provided with 20 small holes with a diameter of 1.4 mm attached to the tip of the extruder is cooled and solidified in a water tank at 20 ° C. Styrene-based resin particles having a weight of 1.0 mg were obtained. At this time, the temperature of the resin at the tip of the extruder was 248 ° C., and the residence time in the extruder was 3 minutes.
The amount of VOC in the styrene resin particles is shown in Table 2.

[Preparation of effervescent styrene resin particles]
Next, in an autoclave with a stirrer having a volume of 6 L, 200 parts by weight of deionized water, 1 part by weight of tricalcium phosphate, and 0.03 part by weight of sodium dodecylbenzene sulfonate were added to 100 parts by weight of the obtained styrene resin particles. , 1 part by weight of sodium chloride was added and the pressure vessel was sealed. Then, 8 parts by weight of butane (a mixture of 70% normal butane and 30% isobutane) was added as a foaming agent into the pressure vessel over 30 minutes, the temperature was raised to 120 ° C. over 30 minutes, and the mixture was kept as it was for 5 hours. .. After holding, cool to room temperature, take out the resin particles impregnated with the foaming agent from the autoclave, wash with hydrochloric acid, wash with water, dehydrate with a centrifuge, and then use an air flow dryer to remove the moisture adhering to the surface of the resin particles. The particles were dried to obtain effervescent styrene resin particles. The amount of VOC in the effervescent styrene resin particles is shown in Table 2.

[Preparation of preliminary foam particles]
After dry-blending 0.1 part by weight of zinc stearate with 100 parts by weight of the obtained effervescent styrene resin particles, the particles were put into a preliminary foaming machine [BHP-300, manufactured by Daikai Kogyo Co., Ltd.]. Steam of 08 MPa was introduced into a pre-foaming machine and foamed to obtain pre-foamed particles having a foaming ratio of 40 times.

[Preparation of foam molded product]
The obtained preliminary foamed particles were filled in an in-mold molding die (400 mm × 300 mm × thickness 25 mm) attached to a styrofoam molding machine [KR-57, manufactured by Daisen Kogyo Co., Ltd.] and 0.06 MPa. A rectangular parallelepiped styrene-based foam molded product was introduced, left in a drying chamber at a temperature of 40 ° C. for 1 hour, and taken out to room temperature. In the foam molded body taken out from the dryer, in order to prevent absorption of VOC released from other foams, the foam molded body is made of aluminum foil and Saran Wrap manufactured by Asahi Kasei Corporation until the measurement. Wrapped in (registered trademark) and stored at room temperature. The amount of VOC in the foam molded product is shown in Table 2.
(Example 2)
The same operation as in Example 1 was performed except that the amount of water was changed to 1.0 weight. Table 2 shows the evaluation results.
(Example 3)
The same operation as in Example 1 was performed except that the amount of water was changed to 2.0 weight. Table 2 shows the evaluation results.
(Example 4)
The same operation as in Example 3 was performed except that the styrene resin was changed to (A2). Table 2 shows the evaluation results.
(Example 5)
The same operation as in Example 3 was performed except that the styrene resin was changed to (A3). Table 2 shows the evaluation results.
(Example 6)
The same operation as in Example 3 was carried out except that the heat stabilizer was a combined system of 0.15 parts by weight of the heat stabilizer (B1) and 0.05 parts by weight of (B2). Table 2 shows the evaluation results.
(Example 7)
The same operation as in Example 3 was carried out except that the heat stabilizer was a combined system of 0.3 parts by weight of the heat stabilizer (B1) and 0.1 part by weight of (B2). Table 2 shows the evaluation results.
(Example 8)
The same operation as in Example 3 was carried out except that the heat stabilizer (B1) was a combined system of 0.4 parts by weight of the heat stabilizer (B1) and 0.2 parts by weight of (B2). Table 2 shows the evaluation results.
(Example 9)
The same operation as in Example 3 was performed except that the flame retardant (C1) was not added. Table 2 shows the evaluation results.
(Example 10)
The same operation as in Example 3 was performed except that the cylinder temperature of the molten portion was changed to 220 ° C. Table 2 shows the evaluation results.
(Example 11)
The same operation as in Example 3 was performed except that the foaming agent impregnation temperature was changed to 115 ° C. Table 2 shows the evaluation results.
(Example 12)
The same operation as in Example 3 was performed except that the foaming agent impregnation temperature was changed to 105 ° C. Table 2 shows the evaluation results.
(Example 13)
The resin particles prepared in Example 1 were further passed through an extruder twice under the extrusion conditions of Example 1 to prepare resin particles. Then, the foamable resin particles were obtained by the same operation as in Example 1. Table 2 shows the evaluation results.

(Comparative Example 1)
The same operation as in Example 3 was performed except that no water was added. Table 2 shows the evaluation results.
(Comparative Example 2)
The same operation as in Example 4 was performed except that no water was added. Table 2 shows the evaluation results.
(Comparative Example 3)
The same operation as in Example 5 was performed except that no water was added. Table 2 shows the evaluation results.
(Comparative Example 4)
The same operation as in Example 1 was performed except that the amount of water was changed to 6.0 weight. Table 2 shows the evaluation results.
(Comparative Example 5)
The same operation as in Example 3 was performed except that the degree of vacuum at the time of extrusion was changed to 0 MPaG (atmospheric pressure). Table 2 shows the evaluation results.
(Comparative Example 6)
The same operation as in Example 3 was performed except that the degree of vacuum at the time of extrusion was changed to −0.04 MPaG. Table 2 shows the evaluation results.
(Comparative Example 7)
The same operation as in Example 3 was carried out except that the heat stabilizer was not added. Table 2 shows the evaluation results.
(Comparative Example 8)
The same operation as in Example 9 was performed except that no water was added. Table 2 shows the evaluation results.
(Comparative Example 9)
The same operation as in Example 3 was performed except that the cylinder temperature of the molten portion was changed to 260 ° C. Table 2 shows the evaluation results.
(Comparative Example 10)
The same operation as in Example 3 was performed except that the foaming agent impregnation temperature was changed to 98 ° C. Table 2 shows the evaluation results.
(Comparative Example 11)
Commercially available styrene-based effervescent resin particles (manufactured by Kaneka Corporation, LVF) were evaluated. Table 2 shows the evaluation results.

Claims (7)

After melt-kneading 0.01 to 5 parts by weight of water and 0.05 to 0.6 parts by weight of the heat stabilizer with respect to 100 parts by weight of the styrene resin, the volatile organic components are evacuated from the inside of the extruder. A process of producing styrene resin particles by suction treatment under the condition of -0.08 MPaG or less and the cylinder temperature of the molten part at 200 ° C to 250 ° C, extruding through a die having small holes, and then cutting with a cutter.
A step of suspending the styrene-based resin particles obtained in the above step in water and impregnating the styrene-based resin particles with a foaming agent at a temperature of 100 ° C. to 120 ° C.
A method for producing effervescent styrene resin particles. The amount of volatile organic components (total amount of styrene monomer and ethylbenzene) of the styrene-based resin particles produced in the step of producing the styrene-based resin particles is less than 200 ppm.
The method for producing foamable styrene resin particles according to claim 1. In the step of producing the styrene-based resin particles, 0.5 parts by weight or more and 3 parts by weight of water are added to 100 parts by weight of the styrene-based resin.
The method for producing effervescent styrene resin particles according to claim 1 or 2. The heat stabilizer is characterized by being at least one compound selected from the group consisting of hindered amine compounds, phosphorus compounds and epoxy compounds.
The method for producing effervescent styrene resin particles according to any one of claims 1 to 3. The heat stabilizer is a phosphorus-based stabilizer and a hindered amine-based stabilizer.
It is characterized in that 0.025 to 0.3 parts by weight of a phosphorus-based stabilizer and 0.025 to 0.3 parts by weight of a hindered amine-based stabilizer are added to 100 parts by weight of a styrene-based resin.
The method for producing effervescent styrene resin particles according to any one of claims 1 to 4. The foaming agent is characterized by being at least one compound selected from the group consisting of normal butane, isobutane, normal pentane, isopentane, cyclopentane and neopentane.
The method for producing effervescent styrene resin particles according to any one of claims 1 to 5. A step of heating the effervescent styrene-based resin particles produced by the production method according to any one of claims 1 to 6 and pre-foaming them to obtain pre-foamed particles.
A step of filling the molding cavity with the preliminary foamed particles obtained in the above step and foaming molding in the mold.
A method for manufacturing a foam molded article.