KR20240007288A - Expandable styrene-based resin particles, pre-expanded styrene-based resin particles, and styrene-based resin foam molded articles - Google Patents

Abstract

Provided are expandable styrene-based resin particles with high environmental contribution, which include a styrene-based resin and a resin component containing a resin other than styrene-based resin, and which have excellent mechanical strength in molded articles, and a method for producing the same. Additionally, pre-expanded styrene-based resin particles obtained from such expandable styrene-based resin particles are provided. Additionally, a styrene-based resin foam molded body molded from such expandable styrene-based resin particles or pre-expanded styrene-based resin particles is provided. The expandable styrene-based resin particles according to an embodiment of the present invention include 70% by mass to 99% by mass of a styrene-based resin (A) and 1% by mass to 30% by mass of a resin other than the styrene-based resin (A) (B). Expandable styrene-based resin particles containing a resin component and a volatile foaming agent, wherein 50% by mass or more of the styrene-based resin (A) is a recycled styrene-based resin, and the resin (B) contains an AS resin, The content ratio of the AS resin is 0.001% by mass to 20% by mass with respect to the styrene resin (A).

Description

Expandable styrene-based resin particles, pre-expanded styrene-based resin particles, and styrene-based resin foam molded articles

The present invention relates to expandable styrene resin particles, pre-expanded styrene resin particles, and styrene resin foam molded articles.

Because foam molded bodies are lightweight and have excellent thermal insulation and mechanical strength, they are widely used in insulation materials used in houses and automobiles, insulation materials used in building materials, packaging materials for transportation such as fish crates and food containers, and cushioning materials. Among them, in-mold foam molded products manufactured using expandable particles (typically expandable polystyrene resin particles or pre-foamed styrene resin particles pre-foamed) are widely used for the advantage of being easy to obtain the desired shape. . This foam molded body is composed of a plurality of foamable particles fused together.

Styrene-based resin foam molded products, which are typical foam molded products, have the disadvantage of being vulnerable to impact and being weak to oils and solvents due to the characteristics of styrene-based resins. To overcome these drawbacks, foams made of olefin-based resins such as ethylene-based resins and propylene-based resins, and foams made of polymers of ethylene and styrene have been proposed (for example, patent document 1). However, since the volatile foaming agent impregnated into the expandable olefin resin particles or the expandable ethylene/styrene polymer particles, which serve as raw materials, is prone to dispersion, it is necessary to quickly pre-foam these foams after manufacturing them. There is a problem that the particles need to be stored in a pressurized container, which causes complexity in manufacturing and labor for storage.

Additionally, a foam molded article has been proposed in which a styrene-based resin and a resin other than the styrene-based resin are melted and blended in advance using a kneader such as an extruder, impregnated with a volatile foaming agent, and then foamed. Specifically, a technique has been proposed for a method of producing a foam in which pellets obtained by heat-melting a vinyl aromatic polymer raw material containing a resin other than a styrene resin are impregnated with a foaming agent and foamed (for example, Patent Document 2). However, in this technology, resins other than styrene resins are mixed to adjust the cell diameter of the foam, and the content ratio of resins other than styrene resins in the resin component is small, and mixing resins other than styrene resins is not necessary. It is not related to the improvement of the mechanical properties of the styrene-based resin foam molded product.

Meanwhile, as voices calling for the establishment of a circular society grow louder, in the materials field as well, there is a demand for a shift away from fossil fuels, and the use of bioplastics as a replacement for plastics derived from fossil fuels is attracting attention. . Representative examples of bioplastics include biomass plastics made from biomass and biodegradable plastics not made from biomass. Biomass is an organic compound photosynthesized from carbon dioxide and water, and when used, it becomes carbon dioxide and water again, so-called carbon-neutral renewable energy. In recent years, the commercialization of biomass plastics made from these biomass materials is rapidly progressing, and attempts are being made to produce various resins from biomass materials (for example, patent document 3).

Additionally, the amount of plastic waste is increasing every year. Most of the plastic waste is disposed of by incineration or landfill, but it has become a major social problem such as environmental pollution, global warming, and lack of landfill treatment plants. For this reason, there is a strong social demand for the reuse of plastic waste, and various studies are being conducted on recycling of plastic waste, such as the implementation of the Home Appliance Recycling Act. While various recycling methods have been proposed, material recycling, which reuses plastic waste as a plastic member of products, is attracting attention from the viewpoint of resource circulation and environmental load reduction.

Japanese Patent Publication No. 48-101457 Japanese Patent Publication No. 47-26097 Japanese Patent Publication No. 2019-182528

The present invention was made to solve the above-described conventional problems, and its main purpose is to provide expandable styrene-based resin particles with a high environmental contribution, which include a styrene-based resin and a resin component containing a resin other than styrene-based resin, and to provide foamable styrene-based resin particles for use in molded articles. The object is to provide expandable styrene-based resin particles with excellent mechanical strength and a method for producing the same. Furthermore, the object is to provide pre-expanded styrene-based resin particles obtained from such expandable styrene-based resin particles. Furthermore, the object is to provide a styrene-based resin foam molded body molded from such expandable styrene-based resin particles or pre-expanded styrene-based resin particles.

The expandable styrene-based resin particles according to an embodiment of the present invention include:

Expandable styrene containing a resin component containing 70% to 99% by mass of styrene resin (A) and 1% to 30% by mass of a resin (B) other than the styrene resin (A), and a volatile foaming agent. As a resin particle,

At least 50% by mass of the styrene-based resin (A) is recycled styrene-based resin,

The resin (B) includes AS resin,

The content ratio of the AS resin is 0.001% by mass to 20% by mass with respect to the styrene resin (A).

In one embodiment, the styrene-based resin (A) is polystyrene.

In one embodiment, the resin (B) contains ABS resin.

In one embodiment, the content ratio of the ABS resin is 0.001% by mass to 5% by mass with respect to the styrene resin (A).

In one embodiment, the resin (B) contains PC resin.

In one embodiment, the content ratio of the PC resin is 0.001% by mass to 5% by mass with respect to the styrene resin (A).

The pre-foamed styrene-based resin particles according to an embodiment of the present invention,

Pre-foamed styrene-based resin particles formed by pre-foaming the expandable styrene-based resin particles,

The volume expansion ratio of the pre-expansion is 1.6 times or more and less than 80 times.

The styrene-based resin foam molded body according to the embodiment of the present invention is molded from the above-mentioned expandable styrene-based resin particles.

The styrene-based resin foam molded body according to the embodiment of the present invention is molded from the pre-expanded styrene-based resin particles.

According to the present invention, expandable styrene-based resin particles with high environmental contribution, which include a styrene-based resin and a resin component containing a resin other than styrene-based resin, and which have excellent mechanical strength of molded articles, and a method for producing the same. can be provided. Additionally, pre-expanded styrene-based resin particles obtained from such expandable styrene-based resin particles can be provided. In addition, a styrene-based resin foam molded body molded from such expandable styrene-based resin particles or pre-expanded styrene-based resin particles can be provided.

1 is a schematic cross-sectional view showing an example of an apparatus suitable for producing expandable styrene-based resin particles according to an embodiment of the present invention.

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

In this specification, “(meth)acrylic” means acrylic and/or methacrylic, and “(meth)acrylate” means acrylate and/or methacrylate.

≪≪A. Expandable styrene resin particles≫≫

The expandable styrene-based resin particles according to the embodiment of the present invention have the shape of particles as a whole.

The average particle diameter of the expandable styrene resin particles according to the embodiment of the present invention is preferably 0.3 mm to 3.0 mm, and more preferably 0.3 mm to 2.0 mm. The average particle diameter can be measured based on JIS Z 8815. Specifically, the average particle diameter is a value measured from the particle size distribution according to the sieve test of JIS Z 8815 with the particle diameter at 50% of the integrated value. As the shape of the expandable styrene resin particles, any appropriate shape can be adopted as long as it does not impair the effect of the present invention. Specific examples of such shapes include, for example, a spherical shape, a substantially spherical shape, an elliptical sphere shape (egg shape), a cylindrical shape, a substantially cylindrical shape, etc.

The MFR of the expandable styrene-based resin particles according to the embodiment of the present invention is preferably 2 g/10 min to 20 g/10 min, and more preferably 3 g/10 min to 18 g, since the effect of the present invention can be more expressed. /10min, more preferably 4g/10min to 16g/10min, and particularly preferably 5g/10min to 14g/10min. Meanwhile, the MFR of the expandable styrene resin particles according to the embodiment of the present invention is a value measured under the conditions of 200°C and a load of 5 kg.

The weight average molecular weight of the expandable styrene-based resin particles according to the embodiment of the present invention is preferably 150,000 to 300,000, more preferably 160,000 to 290,000, since the effect of the present invention can be more expressed. , more preferably 170,000 to 280,000, and particularly preferably 180,000 to 270,000.

The expandable styrene-based resin particles according to an embodiment of the present invention include a resin component containing 70% by mass to 99% by mass of a styrene-based resin and 1% by mass to 30% by mass of a resin other than the styrene-based resin, and a volatile foaming agent. As for the expandable styrene-based resin particles, 50% by mass or more of the styrene-based resin is recycled styrene-based resin.

≪A-1. Resin Ingredients≫

The resin component contains 70% by mass to 99% by mass of styrene resin (A) and 1% by mass to 30% by mass of resin (B) other than the styrene resin (A). The resin (B) may be any resin other than the styrene resin (A). For example, it may be a styrene resin other than the styrene resin (A) (for example, AS resin, ABS resin, etc.).

On the other hand, the content ratio of each resin in the resin component can be analyzed by infrared spectroscopy (single reflection type ATR method). Based on the component peaks of the resin obtained by infrared spectroscopy (single reflection type ATR method), the presence or absence and its content ratio can be confirmed. For example, the presence and content rate of polystyrene is based on the peak observed at 700 cm ^-1 , the presence and content rate of AS resin is based on the peak observed at 2240 cm ^-1 , and the presence and content rate of ABS resin are is based on the peak observed at 965 cm ^-1 , and the presence and content ratio of the PC resin can be confirmed based on the peak observed at 1770 cm ^-1 .

Infrared spectroscopy (single reflection type ATR method) can be used for measurement using, for example, the following equipment and conditions.

Measuring device: Fourier transform infrared spectrophotometer “Nicolet iS10” (manufactured by Thermo SCIENTIFIC)

·Single-reflective horizontal shape ATR: Smart-iTR (manufactured by Thermo SCIENTIFIC)

·ATR crystal: Diamond with ZnSe lens, angle=42°

·Measurement method: One-time ATR method

·Measurement wavenumber range: 4000cm ^-1 to 650cm ^-1

·Wavenumber dependence of measurement depth: not corrected

Detector: Deuterated triglycine sulfate (DTGS) detector and KBr beam splitter

·Resolution: 4cm ^-1

・Number of integration: 16 times (same as for background measurement)

＜A-1-1. Styrene-based resin (A)>

The number of styrene-based resins (A) may be one, and two or more types may be used.

The content ratio of the styrene resin (A) in the resin component is typically 70% by mass to 99% by mass, preferably 72% by mass to 98.5% by mass, and more preferably 75% by mass to 98% by mass. , particularly preferably 77% by mass to 98% by mass, and most preferably 80% by mass to 98% by mass. If the content ratio of the styrene resin (A) in the resin component is within the above range, the effects of the present invention can be more exhibited. If the content ratio of the styrene resin (A) in the resin component is too low beyond the above range, there is a risk that the characteristics of the styrene resin (A) may not be sufficiently expressed. If the content ratio of the styrene resin (A) in the resin component is too high beyond the above range, there is a risk that the mechanical properties of the molded article may be poor.

The styrene-based resin (A) contains a styrene-based polymer containing a styrene-based monomer as a monomer component. The content ratio of the styrene polymer in the styrene resin (A) can be any appropriate content ratio within a range that does not impair the effect of the present invention. This content ratio is preferably 30% by mass or more, more preferably 50% by mass or more, further preferably 70% by mass or more, particularly preferably 80% by mass or more, and most preferably 90% by mass or more. It is more than mass%. The upper limit of the content ratio is preferably 100% by mass or less.

Styrenic monomers include styrene or styrene derivatives. Examples of styrene derivatives include α-methylstyrene, vinyltoluene, chlorostyrene, ethylstyrene, i-propylstyrene, dimethylstyrene, and bromostyrene. The number of styrene-based monomers may be one, or two or more types may be used. The styrenic monomer preferably contains at least styrene. The content ratio of styrene relative to the total amount of styrene-based monomers is preferably 50% by mass or more, more preferably 70% by mass or more, further preferably 90% by mass or more, and particularly preferably 95% by mass. That's it.

The styrene-based polymer containing a styrene-based monomer as a monomer component is preferably a styrene-based polymer containing a styrene-based monomer as a main component of the monomer component. Examples of such styrene-based polymers include copolymers of styrene-based monomers and copolymerization components. Representative examples of copolymerization components include vinyl monomers. In this specification, the “main component” means that the content ratio of the component in all components is preferably 50% by mass or more, more preferably 70% by mass or more, further preferably 90% by mass or more, and is particularly preferred. Specifically, it is 95% by mass or more.

Examples of vinyl monomers include polyfunctional monomers, (meth)acrylic acid ester monomers, maleic acid ester monomers, and fumaric acid ester monomers. The number of vinyl monomers may be one, or two or more types may be used.

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

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

Examples of the maleic acid ester monomer include dimethyl maleate.

Examples of fumaric acid ester monomers include dimethyl fumarate, diethyl fumarate, and ethyl fumarate.

The styrene-based resin (A) is preferably polystyrene because it can further express the effects of the present invention.

Typically, 50% by mass or more of the styrene-based resin (A) is recycled styrene-based resin. The content ratio of the recycled styrene resin in the styrene resin is preferably 60% by mass to 100% by mass, more preferably 70% by mass to 100% by mass, and even more preferably 80% by mass to 100% by mass. , particularly preferably 90% by mass to 100% by mass, and most preferably substantially 100% by mass. If the content ratio of the recycled styrene resin in the styrene resin (A) is within the above range, expandable styrene resin particles with high environmental contribution can be provided.

The number of recycled styrene-based resins may be one, or two or more types may be used.

As the recycled styrene-based resin, any suitable recycled styrene-based resin can be employed as long as it does not impair the effects of the present invention. Examples of such recycled styrene-based resins include recycled plastic materials used in foamed styrene (shaped molded products, block molded products, etc.), foamed sheets (tray containers, sheet scrap materials, etc.), and home appliances. As the recycled styrene-based resin, a commercially available product such as “Epsrem” manufactured by Sekisui Chemical Industries, Ltd., may be used.

If the amount of recycled styrene resin used as the styrene resin (A) is small, there is a risk that the environmental contribution will be lowered.

＜A-1-2. Resin (B)>

Resin (B) is a resin other than styrene resin (A). That is, the resin (B) may be a styrene-based resin other than the styrene-based resin (A), for example, AS resin or ABS resin, or may be a resin other than a styrene-based resin other than the styrene-based resin (A), for example. , PC resin, etc. may be used. The number of resins (B) may be one, or two or more types may be used.

The content ratio of the resin (B) in the resin component is typically 1% by mass to 30% by mass, preferably 1.5% by mass to 28% by mass, more preferably 2% by mass to 25% by mass, especially Preferably it is 2 mass % to 23 mass %, and most preferably is 2 mass % to 20 mass %. If the content ratio of resin (B) in the resin component is within the above range, the effect of the present invention can be more expressed. If the content ratio of resin (B) in the resin component is too low beyond the above range, there is a risk that the mechanical properties of the molded article may be poor. If the content ratio of the resin (B) in the resin component is too high outside the above range, the MFR is lowered, the fluidity deteriorates, the discharge hole of the mold becomes easy to block, and the shear heat generation during discharge from the porous die increases. Since it is difficult to cool even after cutting underwater, there is a risk that coalescence may occur due to particle contact and the number of connected particles may increase.

In an embodiment of the present invention, the resin (B) typically includes AS resin.

The content ratio of AS resin is typically 0.001 mass% to 20 mass%, preferably 0.01 mass% to 18 mass%, and more preferably 0.1 mass% to 15 mass%, relative to the styrene resin (A). , more preferably 1% by mass to 12% by mass, particularly preferably 2% by mass to 10% by mass, and most preferably 3% by mass to 8% by mass. If the content ratio of the AS resin is within the above range, the effects of the present invention can be more expressed, and in particular, the mechanical strength of the molded product can be further improved. In addition, when the content ratio of the AS resin is within the above range, the viscosity of the resin component tends to increase, and when producing the expandable styrene-based resin particles according to the embodiment of the present invention, it becomes difficult for the resin particles immediately after cutting to adhere, The number of adhered particles can be reduced and the occurrence of cut defects can be reduced. Additionally, if the AS resin content is within the above range, the heat resistance of the molded product can be improved. Additionally, if the AS resin content is within the above range, the oil resistance of the molded product can be improved.

In an embodiment of the present invention, the resin (B) may contain ABS resin.

The content ratio of the ABS resin is preferably 5 mass% or less, more preferably 0.001 mass% to 5 mass%, and still more preferably 0.01 mass% to 4 mass%, relative to the styrene resin (A), Particularly preferably, it is 0.1 mass% to 3 mass%, and most preferably is 0.5 mass% to 3 mass%. If the content ratio of the ABS resin is within the above range, the elastic modulus of the molded product can be further improved. In addition, when the content ratio of the ABS resin is within the above range, the bending stress of the molded product can be improved and the bending fatigue resistance can be improved.

In an embodiment of the present invention, the resin (B) may contain PC resin (polycarbonate resin).

The content ratio of the PC resin is preferably 5 mass% or less, more preferably 0.001 mass% to 5 mass%, and even more preferably 0.01 mass% to 4 mass%, relative to the styrene resin (A), Particularly preferably, it is 0.1 mass% to 3 mass%, and most preferably is 0.5 mass% to 3 mass%. If the content ratio of the PC resin is within the above range, the impact resistance of the molded product can be further improved.

Resin (B) may contain any suitable other resin as long as it does not impair the effect of the present invention. Examples of such other resins include olefin resins and polyesters.

≪A-2. Volatile foaming agent≫

The number of volatile foaming agents may be one, or two or more types may be used.

In embodiments of the present invention, the volatile blowing agent preferably includes isopentane. By containing isopentane as a volatile foaming agent, the appearance of the molded product can be excellent. This is presumed to be due to the fact that the plasticizing effect of isopentane improves the elongation of the resin component.

The content ratio of isopentane in the volatile blowing agent is preferably 50% by mass to 100% by mass, more preferably 70% by mass to 100% by mass, further preferably 80% by mass to 100% by mass, and even more preferably. Typically, it is 90% by mass to 100% by mass, particularly preferably 95% by mass to 100% by mass, and most preferably substantially 100% by mass.

In embodiments of the present invention, any suitable volatile foaming agent other than isopentane may be used as the volatile foaming agent, as long as it does not impair the effect of the present invention. Such a volatile blowing agent is preferably an organic compound whose boiling point is below the softening point of the styrene resin and is in a gaseous or liquid state at normal pressure. Specific examples include aliphatic hydrocarbons such as propane, n-butane, isobutane, n-pentane, neopentane, and n-hexane; Alicyclic hydrocarbons such as cyclopentane and cyclopentadiene; Ketones such as acetone and methyl ethyl ketone; Alcohols such as methanol, ethanol, and isopropyl alcohol; ether compounds with low boiling points such as dimethyl ether, diethyl ether, dipropyl ether, and methyl ethyl ether; Halogen-containing hydrocarbons such as trichloromonofluoromethane and dichlorodifluoromethane; etc. can be mentioned. As a volatile blowing agent, inorganic gas such as carbon dioxide, nitrogen, or ammonia may be used.

The content of the volatile foaming agent can be appropriately set depending on the purpose, as long as it is sufficient to form the pre-foamed styrene resin particles and the styrene resin foam molded body. The content of the volatile foaming agent is preferably 1.0 parts by mass to 10 parts by mass, more preferably 2.0 parts by mass to 9.0 parts by mass, with respect to 100 parts by mass of the resin component, in that the effect of the present invention can be more expressed. , more preferably 3.0 parts by mass to 8.0 parts by mass, and particularly preferably 4.0 parts by mass to 7.0 parts by mass.

≪A-3. Other Ingredients≫

The expandable styrene-based resin particles according to the embodiment of the present invention may contain a partial ester of a higher fatty acid and an alcohol in order to prevent the volatile foaming agent from being converted to acid. There may be only one type of partial ester of a higher fatty acid and alcohol, or two or more types may be used. Examples of higher fatty acids include fatty acids with 15 or more carbon atoms such as palmitic acid, stearic acid, oleic acid, linoleic acid, linolenic acid, and behenic acid, and monoglycerides, diglycerides, etc. thereof can be used. Partial esters of higher fatty acids and alcohols preferably include stearic acid monoglyceride and stearic acid diglyceride. The content ratio of the partial ester of the higher fatty acid and alcohol is preferably 0 parts by mass to 3 parts by mass, more preferably 0.5 parts by mass to 3.0 parts by mass, with respect to 100 parts by mass of the resin component. As a method of adding the partial ester of a higher fatty acid and alcohol to the resin component, for example, commonly used methods such as dry blend method, masterbatch method, and melt press method can be adopted.

The expandable styrene-based resin particles according to the embodiment of the present invention may contain a foaming auxiliary agent. The number of foaming aids may be one, or two or more types may be used. Examples of foaming aids include diisobutyl adipate, toluene, cyclohexane, ethylbenzene, liquid paraffin, and palm oil.

The expandable styrene resin particles according to the embodiment of the present invention may contain a flame retardant or a flame retardant auxiliary agent. There may be only one type of flame retardant or flame retardant auxiliary agent, or two or more types may be used. Flame retardants include, for example, tetrabromocyclooctane, hexabromocyclododecane, hexabromocyclohexane, trisdibromopropyl phosphate, tetrabromobisphenol A, tetrabromobisphenol F, and tetrabromobisphenol. A-bis(2,3-dibromo-2-methylpropyl ether), tetrabromobisphenol A-bis(2,3-dibromopropyl ether), tetrabromobisphenol A-diglycidyl ether, 2,2-bis[4'(2'',3''-dibromoalkoxy)-3',5'-dibromophenyl]-propane, tris(tribromophenoxy)triazine. there is. Flame retardant auxiliaries include, for example, cumene hydroperoxide, dicumyl peroxide, t-butyl hydroperoxide, 2,3-dimethyl-2,3-diphenylbutane, 3,4-dimethyl-3,4-di. and phenylhexane.

The expandable styrene-based resin particles according to the embodiment of the present invention may contain a foam regulator such as talc, calcium carbonate, mica, citric acid, or sodium bicarbonate. The number of foam regulators may be one, or two or more types may be used.

The expandable styrene resin particles according to the embodiment of the present invention may contain other additives. Such other additives include, for example, pigments, radiation suppressing components, crosslinking agents, plasticizers, stabilizers, fillers, lubricants, colorants, antistatic agents, electrodeposition agents, weathering agents, anti-aging agents, anti-fogging agents, and fragrances. The number of other additives may be one, or two or more types may be used.

≪A-4. Surface treatment ≫

The expandable styrene resin particles according to the embodiment of the present invention may be surface treated. This surface treatment is preferably surface treatment with at least one type selected from silicone oil, antistatic agent, fatty acid metal salt, and fusion accelerator.

When performing surface treatment with silicone oil on the expandable styrene resin particles according to the embodiment of the present invention, the amount of silicone oil used per 100 parts by mass of the expandable styrene resin particles before surface treatment is preferably 0.001 parts by mass. It is 0.3 part by mass, more preferably 0.003 part by mass to 0.28 part by mass, further preferably 0.005 part by mass to 0.25 part by mass, particularly preferably 0.008 part by mass to 0.23 part by mass, and most preferably 0.01 part by mass. parts to 0.23 parts by mass. If the amount of silicone oil used is outside the above range and is too small, for example, when an antistatic agent is used, there is a risk that the affinity with the antistatic agent during pre-foaming may not be sufficient and static electricity may easily be generated. If the amount of silicone oil used is excessively outside the above range, there is a risk that the surface properties may be lost due to melting of the surface during molding.

There may be only one type of silicone oil, or two or more types may be used.

As the silicone oil, any suitable silicone oil can be employed as long as it does not impair the effect of the present invention. In order to further demonstrate the effect of the present invention, examples of silicone oils include straight silicone oils such as dimethylpolysiloxane, methylphenylpolysiloxane, and methylhydrogenpolysiloxane, and methylphenylpolysiloxane is preferable.

When surface treatment with an antistatic agent is performed on the expanded styrene resin particles according to the embodiment of the present invention, the amount of the antistatic agent used per 100 parts by mass of the expandable styrene resin particles before surface treatment is preferably 0.001 parts by mass. It is 0.3 parts by mass, more preferably 0.005 parts by mass to 0.28 parts by mass, still more preferably 0.01 parts by mass to 0.27 parts by mass, particularly preferably 0.015 parts by mass to 0.26 parts by mass, and most preferably 0.02 parts by mass. It ranges from parts by mass to 0.25 parts by mass. If the amount of the antistatic agent is outside the above range and is too small, there is a risk that static electricity may easily be generated during pre-foaming. If the amount of the antistatic agent is excessively outside the above range, there is a risk that the surface of the pre-expanded styrene resin particles or the styrene resin foam molded body may become sticky.

The number of antistatic agents may be one, or two or more types may be used.

As the antistatic agent, any suitable antistatic agent can be employed as long as it does not impair the effect of the present invention. Since the effect of the present invention can be further expressed, the antistatic agent may include at least one selected from non-ionic surfactants and fatty acid glycerides, and a combination of non-ionic surfactants and fatty acid glycerides is preferred. am.

The number of nonionic surfactants may be one, or two or more types may be used.

As the nonionic surfactant, any suitable nonionic surfactant can be employed as long as it does not impair the effect of the present invention. Nonionic surfactants that can further express the effect of the present invention include, for example, polyethylene glycol, glycerin, polyoxyethylene alkyl ether, polyoxyethylene alkyl ester, polyhydric alcohol, 1-amino-2- Hydroxy compounds can be mentioned. Specific examples of polyoxyethylene alkyl ether include polyoxyethylene cetyl ether, polyoxyethylene oleyl ether, and polyoxyethylene stearyl ether. Specific examples of polyoxyethylene alkyl ester include polyoxyethylene laurate, polyoxyethylene palmitate, polyoxyethylene stearate, and polyoxyethylene oleate. Specific examples of polyhydric alcohols include glycerin and propylene glycol. 1-Amino-2-hydroxy compounds specifically include, for example, N-hydroxyethyl-N-(2-hydroxyalkyl)amine and N,N-bis(hydroxyethyl)dodecylamine. , N,N-bis(hydroxyethyl)tetradecylamine, N,N-bis(hydroxyethyl)hexadecylamine, N,N-bis(hydroxyethyl)octadecylamine, N-hydroxyethyl-N -(2-hydroxytetradecyl)amine, N-hydroxyethyl-N-(2-hydroxyhexadecyl)amine, N-hydroxyethyl-N-(2-hydroxyoctadecyl)amine, N-hydride Roxypropyl-N-(2-hydroxytetradecyl)amine, N-hydroxybutyl-N-(2-hydroxytetradecyl)amine, N-hydroxypentyl-N-(2-hydroxytetradecyl)amine , N-hydroxypentyl-N-(2-hydroxyhexadecyl)amine, N-hydroxypentyl-N-(2-hydroxyoctadecyl)amine, N,N-bis(2-hydroxyethyl)dode Silamine, N,N-bis(2-hydroxyethyl)tetradecylamine, N,N-bis(2-hydroxyethyl)hexadecylamine, N,N-bis(2-hydroxyethyl)octadecylamine , and salts thereof. Polyethylene glycol is preferable as a nonionic surfactant because it can further express the effects of the present invention.

When a nonionic surfactant is employed as at least a part of the antistatic agent, the amount of the nonionic surfactant used per 100 parts by mass of the expandable styrene resin particles before surface treatment is preferably 0.001 parts by mass to 0.3 parts by mass. Preferably it is 0.005 parts by mass to 0.28 parts by mass, more preferably 0.01 parts by mass to 0.27 parts by mass, particularly preferably 0.015 parts by mass to 0.26 parts by mass, and most preferably 0.02 parts by mass to 0.25 parts by mass. . If the amount of the nonionic surfactant is outside the above range and is too small, there is a risk that static electricity may easily be generated during pre-foaming. If the amount of the nonionic surfactant is excessively outside the above range, there is a risk that the surface of the pre-expanded styrene resin particles or the styrene resin foam molded body may become sticky.

There may be only one type of fatty acid glyceride, and two or more types may be used.

As the fatty acid glyceride, any suitable fatty acid glyceride can be employed as long as it does not impair the effect of the present invention. Since the effect of the present invention can be further expressed, the fatty acid glyceride specifically includes, for example, stearic acid monoglyceride and linoleic acid monoglyceride. Since the effect of the present invention can be more expressed, stearic acid monoglyceride is preferable as the fatty acid glyceride.

When fatty acid glyceride is employed as at least a part of the antistatic agent, the amount of fatty acid glyceride per 100 parts by mass of expandable styrene resin particles before surface treatment is preferably 0.001 to 0.3 parts by mass, more preferably It is 0.005 part by mass to 0.28 part by mass, more preferably 0.01 part by mass to 0.27 part by mass, particularly preferably 0.015 part by mass to 0.26 part by mass, and most preferably 0.02 part by mass to 0.25 part by mass. If the amount of fatty acid glyceride is outside the above range and is too small, there is a risk that static electricity may easily be generated during pre-foaming. If the amount of fatty acid glyceride is excessively outside the above range, there is a risk that the surface of the pre-expanded styrene resin particles or the styrene resin foam molded body may become sticky.

When surface treatment with a fatty acid metal salt is performed on the expandable styrene resin particles according to the embodiment of the present invention, the amount of fatty acid metal salt used per 100 parts by mass of the expandable styrene resin particles before surface treatment is preferably 0.005 parts by mass. It is -0.5 part by mass, more preferably 0.007 part by mass -0.45 part by mass, still more preferably 0.01 part by mass -0.4 part by mass, especially preferably 0.015 part by mass -0.35 part by mass, and most preferably 0.02 part by mass. It ranges from parts by mass to 0.3 parts by mass. If the amount of the fatty acid metal salt is outside the above range and is too small, blocking may occur during pre-expansion, and there is a risk that a good styrene-based resin foamed molded product may not be obtained. If the amount of the fatty acid metal salt is excessively outside the above range, a large amount of the metal salt is present during pre-foaming, making it easy to charge and generate static electricity, which may worsen the fusion of the molded product.

There may be only one type of fatty acid metal salt, or two or more types may be used.

As the fatty acid metal salt, any suitable fatty acid metal salt can be employed as long as it does not impair the effect of the present invention. In that the effect of the present invention can be further expressed, examples of fatty acid metal salts include stearic acid metal salts and lauric acid metal salts. Specific examples of metal stearate include magnesium stearate, calcium stearate, zinc stearate, barium stearate, aluminum stearate, and lithium stearate. Specific examples of metal laurate salts include zinc laurate and barium laurate. Magnesium stearate and zinc stearate are preferable as fatty acid metal salts in that the effects of the present invention can be further exhibited.

When surface treatment with a fusion accelerator is performed on the expandable styrene resin particles according to the embodiment of the present invention, the amount of the fusion accelerator used per 100 parts by mass of the expandable styrene resin particles before surface treatment is preferably 0.01 parts by mass. -0.8 parts by mass, more preferably 0.01 parts by mass - 0.7 parts by mass, further preferably 0.01 parts by mass - 0.6 parts by mass, especially preferably 0.01 parts by mass - 0.55 parts by mass, and most preferably 0.013 parts by mass. It ranges from parts by mass to 0.5 parts by mass. If the amount of the fusion accelerator is outside the above range and is too small, there is a risk that the fusion property during molding may decrease, making it impossible to obtain a good styrene-based resin foam molded body. If the amount of the fusion accelerator is too much outside the above range, there is a risk of blocking during pre-foaming.

The number of fusion accelerators may be one, or two or more types may be used.

As the fusion accelerator, any suitable fusion accelerator can be employed as long as it does not impair the effect of the present invention. Since the effect of the present invention can be further expressed, fusion accelerators include, for example, fatty acid triglycerides, fatty acid diglycerides, fatty acid monoglycerides, and vegetable oils. Specific examples of fatty acid triglycerides include lauric acid triglyceride, stearic acid triglyceride, linoleic acid triglyceride, and hydroxystearic acid triglyceride. Specific examples of fatty acid diglycerides include lauric acid diglyceride, stearic acid diglyceride, and linoleic acid diglyceride. Specific examples of fatty acid monoglycerides include lauric acid monoglyceride. Specific examples of the vegetable oil include hydrogenated castor oil. Since the effect of the present invention can be further expressed, hydroxystearic acid triglyceride is preferred as the fusion accelerator.

≪A-5. Method for producing expandable styrene-based resin particles≫

The expandable styrene-based resin particles according to the embodiment of the present invention can be manufactured by any appropriate method within the range that does not impair the effect of the present invention. In order to further demonstrate the effect of the present invention, it is preferably obtained by an underwater cutting method in which a resin composition containing a resin component and a volatile foaming agent is extruded from an extruder and simultaneously cut in water.

The method for producing expandable styrene-based resin particles according to an embodiment of the present invention by an underwater cutting method includes, more specifically, 70% by mass to 99% by mass of styrene-based resin and 1% by mass to 30% by mass of styrene. A resin component containing a resin other than the system resin is supplied to an extruder, heated and melted, a volatile foaming agent is injected from the middle of the extruder, the resulting resin composition is extruded into water through a porous die, and cut under water simultaneously with extrusion. It is made of resin particles.

When cutting in water simultaneously with extrusion, the temperature of the water is preferably 15°C to 60°C, and more preferably 20°C to 50°C. If the temperature of the water is lower than 15°C, cooling of the die surface becomes strong, the hole in the die becomes easily clogged, and the pressure inside the die increases, which may make extrusion difficult. If the temperature of the water is higher than 60°C, there is a risk that it may become difficult to suppress foaming. Additionally, if the temperature of the water exceeds 80°C, there is a risk that the resin particles obtained by cutting may easily adhere.

The temperature of the water is preferably 100°C to 200°C lower than the temperature of the resin composition when entering the die. If the temperature difference between the temperature of the water and the temperature of the resin composition is less than 100°C, cooling of the resulting resin particles may become insufficient and it may be difficult to suppress foaming, and the temperature difference between the temperature of the water and the temperature of the resin composition may be 200°C. If it exceeds, there is a risk that the resin particles may be deformed due to the temperature difference between the surface and the inside of the resulting resin particles, and may not have a spherical shape.

In the underwater cutting method, a porous die with 50 to 500 discharge holes is used, and the water pressure is preferably adjusted to 0.10 MPa to 2.00 MPa and the discharge amount is adjusted to 50 kg/hour to 300 kg/hour. In the underwater cutting method, the water pressure corresponds to the resistance force when the resin is extruded from the die into the water, and the discharge amount corresponds to the force in the extrusion direction when the resin composition is extruded from the die into the water. Therefore, in the underwater cutting method, expandable styrene-based resin particles can be satisfactorily manufactured by appropriately adjusting the water pressure and discharge amount. In particular, when using a recycled styrene resin as a resin component, the molecular weight tends to decrease due to the heat history that the recycled styrene resin receives during recycling, and the fluidity tends to increase accordingly, and further, the moisture derived from the recycled raw material tends to increase. Since additives are included in arbitrary amounts, fluidity and viscoelasticity change, making it necessary to strictly adjust the water pressure and discharge amount in the underwater cutting method.

The water pressure in the underwater cutting method is preferably 0.12 MPa to 1.90 MPa, more preferably 0.13 MPa to 1.85 MPa, further preferably 0.15 MPa to 1.80 MPa, and particularly preferably 0.20 MPa to 1.60 MPa. am.

The discharge amount in the underwater cutting method is preferably 60 kg/hour to 280 kg/hour, more preferably 80 kg/hour to 270 kg/hour, and even more preferably 100 kg/hour to 260 kg/hour. time, and is particularly preferably 120 kg/hour to 250 kg/hour.

An example of a device suitable for producing expandable styrene-based resin particles according to an embodiment of the present invention by an underwater cutting method is shown in FIG. 1. This manufacturing apparatus has a raw material supply hopper 11 for injecting resin components upstream of the resin flow direction (direction from left to right in FIG. 1) and a high-pressure pump 13 on the downstream side of the resin flow direction. It is formed to cover the extruder 1 with the foaming agent supply port 12 and the porous die 2 at the ends of the resin flow direction, respectively, and the outlet of the porous die 2, so that the cutter 31 can be rotated therein. In addition to being arranged neatly, there is a cutting room (3) configured to circulate water inside, a water tank (6) and a water supply pump (4) for supplying water to the cutting room (3), and a cutting room (3) inside the cutting room (3). A dehydration dryer (5) that introduces the cut expandable styrene resin particles together with water and separates the water and expandable styrene resin particles, and a container (7) that stores the expandable styrene resin particles separated in the dehydration dryer (5). ) and is composed of.

As the extruder 1, a known extruder used in extrusion molding of a resin composition can be used. Examples of such extruders include single-screw extruders, twin-screw extruders, and tandem extruders. The extruder 1 injects the resin component from the raw material supply hopper 11, heats and kneads it within the extruder 1, and transfers the melted mixture downstream in the resin flow direction. When the molten mixture reaches the volatile foaming agent supply port 12, the volatile foaming agent pumped from the high pressure pump 13 is mixed into the molten mixture. Thereafter, the obtained resin composition is extruded from the porous die 2 into the cutting chamber 3, comes into contact with water, and is cut by the cutter 31 in water. The cut resin composition becomes spherical particles with a substantially uniform particle diameter, and is conveyed from the cutting chamber 3 to the dehydration dryer 5 by a circulating water flow. The expandable styrene resin particles obtained by being separated from water and dried in the dehydration dryer (5) are stored in the container (7), while the water is sent to the water tank (6).

≪≪B. Pre-expanded styrene resin particles≫≫

Pre-foamed styrene-based resin particles are made by pre-foaming expandable styrene-based resin particles.

The pre-expanded styrene-based resin particles have an average cell diameter of preferably 0.04 mm to 1.10 mm, more preferably 0.04 mm to 1.00 mm, further preferably 0.04 mm to 0.90 mm, and particularly preferably 0.04 mm. It is ~0.80mm, and most preferably is 0.04mm~0.70mm. If the average cell diameter of the pre-expanded styrene resin particles is within the above range, blocking during foaming and molding can be further prevented, and in addition, electrification during foaming and molding can be further suppressed, while better fusion properties and surface properties can be achieved. It is possible to provide pre-foamed styrene-based resin particles that exhibit stability and can form a styrene-based resin foam molded body with less static electricity.

That is, the pre-foamed styrene-based resin particles according to the embodiment of the present invention are prepared by pre-foaming the expandable styrene-based resin particles described in item A above. Pre-foaming involves foaming expandable styrene resin particles to a desired volumetric expansion ratio (bulk density) using steam or the like. The volumetric expansion ratio of the pre-foamed styrene resin particles is preferably 1.6 times or more and less than 80 times, more preferably 2 times to 78 times, further preferably 10 times to 75 times, and particularly preferably 15 times. ~72 times. Bulk density is the reciprocal of the volumetric expansion ratio. The volume expansion ratio and bulk density are obtained, for example, as follows. When the volumetric expansion ratio of the pre-foamed styrene resin particles is within the above range, blocking during foaming and molding can be further prevented, and in addition, electrification during foaming and molding can be further suppressed, and better fusion properties can be achieved. It is possible to provide pre-foamed styrene-based resin particles that exhibit surface properties and can be used to mold styrene-based resin foam molded products with less static electricity.

W(g) is collected from expandable styrene resin particles as a measurement sample. This measurement sample is naturally dropped into a measuring cylinder, and the volume V (cm3) of the measurement sample dropped into the measuring cylinder is measured using an apparent density meter based on JIS K 6911. From the mass and volume of the measured sample, the volume expansion multiple and volume density can be calculated based on the following formula.

Volume expansion ratio (time = cm3/g) = Volume of measurement sample (V) / Mass of measurement sample (W)

Bulk density (g/㎤) = Mass of measurement sample (W)/Volume of measurement sample (V)

In one representative embodiment, the pre-expanded styrene-based resin particles can be used for molding a styrene-based resin foam molded body. In another embodiment, the pre-expanded styrene-based resin particles can be used as is as a buffering agent, insulating material, etc. When using the pre-expanded styrene-based resin particles as is, the pre-expanded styrene-based resin particles can preferably be used as a filler in which a plurality of pre-expanded styrene-based resin particles are filled into an encapsulant.

≪≪C. Styrene resin foam molded body≫≫

The styrene-based resin foam molded article according to one embodiment of the present invention is a styrene-based resin foam molded article molded from expandable styrene-based resin particles. A styrene-based resin foam molded article according to another embodiment of the present invention is a styrene-based resin foam molded article molded from pre-expanded styrene-based resin particles obtained by pre-foaming expandable styrene-based resin particles.

The styrene-based resin foam molded body typically contains expanded styrene-based resin particles obtained by further expanding pre-expanded styrene-based resin particles (hereinafter, sometimes simply referred to as “foamed particles”).

A styrene-based resin foamed molded body is typically composed of a plurality of foamed particles fused together.

A styrene-based resin foam molded body can typically be produced by putting pre-expanded styrene-based resin particles into a mold having a predetermined shape according to the purpose and performing in-mold foam molding. More specifically, in-mold foam molding involves (i) filling pre-foamed styrene-based resin particles into a closed mold with a large number of small holes, (ii) pre-foamed styrene-based resin particles using a heat medium (e.g., pressurized water vapor, etc.) This includes obtaining foamed particles by heating and foaming the resin particles, (iii) filling the voids between the foamed particles by heating and foaming, and integrating the foamed particles by fusing them with each other. The density of the styrene resin foam molded body can be appropriately set depending on the purpose. The density of the styrene-based resin foam molded body can be adjusted, for example, by previously adjusting the volumetric expansion ratio of the pre-foamed styrene-based resin particles filled into the mold, or by adjusting the filling amount of the pre-foamed styrene-based resin particles into the mold. .

The temperature of heating foaming (substantially the temperature of the heat medium) is preferably 90°C to 150°C, more preferably 110°C to 130°C. The heating foaming time is preferably 5 seconds to 120 seconds, and more preferably 10 seconds to 80 seconds. The molding vapor pressure (injection gauge pressure of the heat medium) for heating foaming is preferably 0.04 MPa to 0.1 MPa, and more preferably 0.06 MPa to 0.09 MPa. If heated foaming is performed under these conditions, the expanded particles can be favorably fused to each other.

If necessary, the pre-expanded styrene resin particles may be aged before molding the styrene resin foam molded body. The maturation temperature of the pre-expanded styrene resin particles is preferably 20°C to 60°C. If the ripening temperature is too low, an excessively long ripening time may be required. If the aging temperature is too high, the foaming agent in the pre-expanded styrene-based resin particles may disperse and formability may deteriorate.

The volumetric expansion ratio of the expanded particles in the styrene-based resin foam molded body is preferably 1.6 to 80 times, more preferably 2 to 78 times, further preferably 10 to 75 times, especially preferably. In other words, it is 15 to 72 times.

The styrene-based resin foam molded article according to one embodiment of the present invention has excellent mechanical strength, and the 10% compressive stress of the 60 times the foam molded article is preferably 0.06 MPa or more, and more preferably 0.07 MPa to 0.26 MPa. , more preferably 0.08 MPa to 0.25 MPa, and particularly preferably 0.09 MPa to 0.24 MPa.

The styrene-based resin foam molded article according to one embodiment of the present invention has excellent mechanical strength, and the maximum bending stress of the 60-fold foam molded article is preferably 0.11 MPa or more, more preferably 0.12 MPa to 0.35 MPa, More preferably, it is 0.13 MPa to 0.34 MPa, and particularly preferably, it is 0.14 MPa to 0.33 MPa.

≪≪D. Use≫≫

The expandable styrene-based resin particles according to an embodiment of the present invention, the pre-expanded styrene-based resin particles according to an embodiment of the present invention, and the styrene-based resin foam molded body according to an embodiment of the present invention can be employed for any appropriate application. . These uses include, for example, packaging cushioning materials, ice boxes, cushion filling materials, etc., from the viewpoint of making more use of the effects of the present invention.

Example

Hereinafter, the present invention will be specifically described by way of examples, but the present invention is not limited to these examples. Meanwhile, the measurement and evaluation methods for each characteristic are as follows.

＜Evaluation of cemented particle ratio＞

Expandable styrene resin particles that were separated from water and dried in a dehydration dryer were placed in a sieve set with a sieve mesh with a grid spacing of 1.44 mm, and the weight of the particles that did not pass through was measured.

＜Measurement of maximum bending stress＞

Measurement was made based on JIS-A-9511. A molded article measuring 400 mm x 300 mm x 27 mm was prepared, cured for 24 hours in a drying room at a temperature of 40°C, and dried. Three test pieces measuring 75 mm x 300 mm x 27 mm were cut from the molded product, and cured at a temperature of 23°C and a humidity of 50% RH for 24 hours. A bending test jig was mounted on a universal material testing machine (Tensilon UCT-5T), a test piece was set up and down with a surface of 75 mm Then, the maximum point stress (MPa) was calculated. The number of N was set to 3.

＜10% compressive stress measurement＞

Measurement was made based on JIS-A-9511. A molded article measuring 400 mm x 300 mm x 27 mm was prepared, cured for 24 hours in a drying room at a temperature of 40°C, and dried. Five test pieces measuring 50 mm x 50 mm x 27 mm were cut from the molded product, and cured at a temperature of 23°C and a humidity of 50% RH for 24 hours. A compression test jig was mounted on a universal materials testing machine (Tensilon UCT-5T), a test piece was set up and down on a 50 mm x 50 mm surface, a load was applied at a speed of 10 mm/min, and the stress at 10% compression was obtained. (MPa) was calculated. The number of N was set to 5.

＜Evaluation of fusion of molded products＞

A molded article measuring 400 mm x 300 mm x 27 mm was prepared, cured for 24 hours in a drying room at a temperature of 40°C, and dried. A cut of about 2 mm in depth was made in the 400 mm x 300 mm surface of the dried molded product, and the molded product was divided. The foamed particles on the fractured cross section were visually inspected, and the number of broken foamed particles and foamed particles that were not broken by peeling between the particles were counted.

The evaluation criteria were as follows.

◎: Broken expanded particles were 90% or more.

○: Broken expanded particles were 70% or more and less than 90%.

＜Productivity Evaluation＞

As the MFR of the resin decreased (viscosity hardened), the effect on continuous production due to the increase in extruder pressure was determined.

The evaluation criteria were as follows.

○: Pressure 12 MPa or less. It was judged that production was possible without any problems.

△: Pressure 12 to 20 MPa or less. It was determined that strict conditions such as temperature adjustment were necessary for production.

×: Pressure 20 MPa or less. It was determined that extrusion was not possible.

[Example 1]

Recycled styrene-based resin (polystyrene resin recovered from waste home appliances, Sekisui Kaseihin Kanto Co., Ltd., IFS-K, MFR (200°C, 5kgf) = 3.5g/10min): 94% by mass, AS resin (Denka Polymer) Manufactured by GR-AT-R, acrylonitrile-styrene copolymer) (MFR (220°C, 98N) = 13 g/10min, MFR (200°C, 49N) = 1g/10min): 4.0% by mass and ABS resin ( GR-2000, manufactured by Denka Polymer, acrylonitrile-butadiene-styrene copolymer) (MFR (220°C, 98N) = 13g/10min): 1.0% by mass, and PC resin (K-1300Y, manufactured by Teijin, polycarbonate) Resin) (MFR (300°C, 1.2 kg) = 2.8 g/10 min): 1.0% by mass of mixed resin (100% by mass) and talc: 0.7 parts by mass are supplied to a single-screw extruder with a diameter of 100 mm and heated and melted, Isopentane (100%): 5.5 parts by mass as a volatile blowing agent was press-injected into 100 parts by mass of the mixed resin and melt-mixed. Next, the melted resin composition is kneaded and cooled in the extruder, passed through a porous die with extrusion holes ϕ0.5 mm x 312 at a temperature of 181°C, extruded into a cutting chamber filled with water at 70°C, and cut immediately in water. , and dehydrated through a stretching dehydrator to obtain expandable styrene-based resin particles (1) with a bulk density of 0.6 g/cm3 and an average particle diameter of about 1.2 mm.

The extrusion conditions were as follows.

Discharge amount = 146 kg/hour

Screw rotation speed = 70rpm

Extruder pressure=11.6MPa

Gas flow rate = 7.4 kg/hour

Cutter rotation speed = 3000rpm

Water pressure=0.50MPa

With respect to the obtained expandable styrene resin particles (1): 100 parts by mass, zinc stearate: 0.10 parts by mass, stearic acid triglyceride: 0.20 parts by mass, stearic acid monoglyceride: 0.06 parts by mass, and polyethylene glycol: 0.03 parts by mass in a tumbler. It was put into a mixer, stirred for 15 minutes, and the expandable styrene resin particles (1) were surface treated.

The surface-treated expandable styrene-based resin particles (1) were stored in a refrigerator at 15°C for 1 day, then placed in a cylindrical batch foamer with a volume of 25 liters, heated for 300 seconds with steam at a gauge pressure of 0.08 MPa, and preliminarily prepared. Expanded styrene-based resin particles (1) were obtained. The expansion ratio of the pre-expanded styrene resin particles (1) was 70 times.

After leaving the pre-foamed styrene-based resin particles (1) in a room temperature atmosphere for 24 hours, pre-foaming is performed in the cavity of the mold using a molding machine with a mold having a cavity size of 300 mm in height, 400 mm in width, and 27 mm in depth. Styrene-based resin particles (1) are filled, heated for 60 seconds with steam at a gauge pressure of 0.08 MPa, and then cooled until the pressure inside the mold becomes 0.01 MPa, then released from the mold and placed in the mold. A corresponding plate-shaped styrene resin foam molded body (1) was obtained. The expansion ratio of the styrene resin foam molded body (1) was 60 times. Thereafter, the styrene resin foam molded body (1) was dried in a drying room at 30°C.

The obtained styrene resin foam molded body (1) was evaluated.

The results are shown in Table 1.

[Examples 2 to 4]

Except that the resin ratio and various conditions were changed as shown in Table 1, the same procedure as in Example 1 was carried out to produce expandable styrene-based resin particles (2) to (4) and pre-expanded styrene-based resin particles (2) to (4). ) was obtained. The expansion ratio of the pre-expanded styrene resin particles (2) to (4) was each 70 times.

After leaving the pre-expanded styrene-based resin particles (2) to (4) in a room temperature atmosphere for 24 hours, the mold was molded using a molding machine with a cavity size of 300 mm in height, 400 mm in width, and 27 mm in depth. Pre-expanded styrene-based resin particles (2) to (4) are filled in the cavity, heated for 60 seconds with steam at a gauge pressure of 0.08 MPa, and then cooled until the pressure inside the mold becomes 0.01 MPa, and then molded. The mold was released from the mold to obtain plate-shaped styrene resin foam molded bodies (2) to (4) corresponding to the mold. The expansion ratios of the styrene resin foam molded bodies (2) to (4) were each 60 times. Thereafter, the styrene resin foam molded bodies (2) to (4) were dried in a drying room at 30°C.

The obtained styrene-based resin foamed molded bodies (2) to (4) were evaluated.

The results are shown in Table 1.

[Comparative Example 1]

Except that the resin ratio and various conditions were changed as shown in Table 1, the same procedure as in Example 1 was performed to obtain expandable styrene-based resin particles (C1) and pre-expanded styrene-based resin particles (C1). The expansion ratio of the pre-expanded styrene resin particles (C1) was 70 times.

After leaving the pre-foamed styrene-based resin particles (C1) in a room temperature atmosphere for 24 hours, pre-foaming is performed in the cavity of the mold using a molding machine with a mold having a cavity size of 300 mm in height, 400 mm in width, and 27 mm in depth. Styrene-based resin particles (C1) are filled, heated for 60 seconds with steam at a gauge pressure of 0.08 MPa, and then cooled until the pressure inside the mold becomes 0.01 MPa, then released from the mold and placed in the mold. A corresponding plate-shaped styrene resin foam molded body (C1) was obtained. The expansion ratio of the styrene resin foam molded body (C1) was 60 times. Thereafter, the styrene resin foam molded body (C1) was dried in a drying room at 30°C.

The obtained styrene resin foam molded body (C1) was evaluated.

The results are shown in Table 1.

[Comparative Example 2]

Except that the resin ratio and various conditions were changed as shown in Table 1, the same procedure as in Example 1 was performed to obtain expandable styrene-based resin particles (C2) and pre-expanded styrene-based resin particles (C2). The expansion ratio of the pre-expanded styrene resin particles (C2) was each 70 times.

After leaving the pre-foamed styrene-based resin particles (C2) in a room temperature atmosphere for 24 hours, pre-foaming is performed in the cavity of the mold using a molding machine with a mold having a cavity size of 300 mm in height, 400 mm in width, and 27 mm in depth. Styrene-based resin particles (C2) are filled, heated for 60 seconds with steam at a gauge pressure of 0.08 MPa, and then cooled until the pressure inside the mold becomes 0.01 MPa, then released from the mold and placed in the mold. An attempt was made to produce a corresponding plate-shaped styrene resin foam molded body, but the particle diameter was too large and the appearance was defective, making production impossible.

[Comparative Example 3]

An attempt was made to produce expandable styrene-based resin particles in the same manner as in Example 1, except that the resin ratio and various conditions were changed as shown in Table 1, but production was not possible due to the interlock of the extruder being stopped.

[Comparative Example 4]

Except that the volatile blowing agent was changed to n-pentane, the same procedure as in Comparative Example 1 was performed to obtain expandable styrene-based resin particles (C4) and pre-expanded styrene-based resin particles (C4). The expansion ratio of the pre-expanded styrene resin particles (C4) was 50 times.

After leaving the pre-foamed styrene-based resin particles (C4) in a room temperature atmosphere for 24 hours, pre-foaming is performed in the cavity of the mold using a molding machine with a mold having a cavity size of 300 mm in height, 400 mm in width, and 27 mm in depth. Styrene-based resin particles (C4) are filled, heated for 60 seconds with steam at a gauge pressure of 0.08 MPa, and then cooled until the pressure inside the mold becomes 0.01 MPa, then released from the mold and placed in the mold. A corresponding plate-shaped styrene resin foam molded body (C4) was obtained. The expansion ratio of the styrene resin foam molded body (C4) was 40 times. Thereafter, the styrene resin foam molded body (C4) was dried in a drying room at 30°C.

The obtained styrene resin foam molded body (C4) was evaluated.

The results are shown in Table 1.

[Example 5]

With respect to the expandable styrene resin particles (1) obtained in Example 1, the content ratio of each resin in the resin components contained therein was analyzed by infrared spectroscopy (single reflection type ATR method) using the following device. Based on the component peaks of the resin observed by this analysis, the presence or absence of mixtures and their content ratio were confirmed. Meanwhile, the presence and content ratio of polystyrene is based on the peak observed at 700 cm ^-1 , the presence and content ratio of AS resin is based on the peak observed at 2240 cm ^-1 , and the presence and content ratio of ABS resin is 965 Based on the peak observed at cm ^-1 , the presence and content ratio of the PC resin were confirmed based on the peak observed at 1770 cm ^-1 .

Measuring device: Fourier transform infrared spectrophotometer “Nicolet iS10” (manufactured by Thermo SCIENTIFIC)

·Single-reflective horizontal shape ATR: Smart-iTR (manufactured by Thermo SCIENTIFIC)

·ATR crystal: Diamond with ZnSe lens, angle=42°

·Measurement method: One-time ATR method

·Measurement wavenumber range: 4000cm ^-1 to 650cm ^-1

·Wavenumber dependence of measurement depth: not corrected

Detector: Deuterated triglycine sulfate (DTGS) detector and KBr beam splitter

·Resolution: 4cm ^-1

・Number of integration: 16 times (same as for background measurement)

As a result of the measurement, it was found that the resin components contained 94.0% by mass of polystyrene, 4.0% by mass of AS resin, 1.0% by mass of ABS resin, and 1.0% by mass of PC resin.

[Example 6]

For the expandable styrene-based resin particles (2) obtained in Example 2, the content ratio of each resin in the resin component contained therein was confirmed in the same manner as in Example 5.

As a result of the measurement, it was found that the resin components contained 85.0% by mass of polystyrene, 10.0% by mass of AS resin, 2.5% by mass of ABS resin, and 2.5% by mass of PC resin.

[Example 7]

Regarding the expandable styrene-based resin particles (3) obtained in Example 3, the content ratio of each resin in the resin component contained therein was confirmed in the same manner as in Example 5.

As a result of the measurement, it was found that the resin components contained 70.0% by mass of polystyrene, 20.0% by mass of AS resin, 5.0% by mass of ABS resin, and 5.0% by mass of PC resin.

[Example 8]

With respect to the expandable styrene-based resin particles (4) obtained in Example 4, the content ratio of each resin in the resin component contained therein was confirmed in the same manner as in Example 5.

As a result of the measurement, it was found that the resin component contained 98.0% by mass of polystyrene and 2.0% by mass of AS resin.

The expandable styrene-based resin particles, pre-expanded styrene-based resin particles, and styrene-based resin foam molded bodies according to an embodiment of the present invention are used in insulation materials used in houses and automobiles, insulation materials used in building materials, etc., fish boxes, food containers, etc. It is preferably used in packaging materials for transportation, packaging cushioning materials, ice boxes, and cushion filling materials. More specifically, expandable styrene-based resin particles, pre-expanded styrene-based resin particles, and styrene-based resin foamed molded products include wall insulators, floor insulators, roof insulators, automobile insulators, hot water tank insulators, piping insulators, It is preferably used in thermal insulation materials for solar systems, thermal insulation materials for hot water heaters, containers for food and industrial products, packaging materials for fish and agricultural products, fill materials, core materials for tatami mats, packaging cushioning materials, ice boxes, and cushion filling materials.

1 extruder
2 perforated die
3 cutting room
4 water pump
5 Dehydration dryer
6 water tank
7 courage
11 Raw material feeding hopper
12 Volatile foaming agent supply port
13 high pressure pump
31 cutter

Claims (9)

Expandable styrene containing a resin component containing 70% to 99% by mass of styrene resin (A) and 1% to 30% by mass of a resin (B) other than the styrene resin (A), and a volatile foaming agent. As a resin particle,
At least 50% by mass of the styrene-based resin (A) is recycled styrene-based resin,
The resin (B) includes AS resin,
Expandable styrene-based resin particles wherein the content ratio of the AS resin is 0.001% by mass to 20% by mass with respect to the styrene-based resin (A). According to claim 1,
Expandable styrene-based resin particles, wherein the styrene-based resin (A) is polystyrene. The method of claim 1 or 2,
Expandable styrene-based resin particles wherein the resin (B) contains an ABS resin. According to claim 3,
Expandable styrene resin particles wherein the content ratio of the ABS resin is 0.001% by mass to 5% by mass with respect to the styrene resin (A). The method according to any one of claims 1 to 4,
Expandable styrene-based resin particles wherein the resin (B) contains a PC resin. According to claim 5,
Expandable styrene-based resin particles wherein the content ratio of the PC resin is 0.001% by mass to 5% by mass with respect to the styrene-based resin (A). Pre-foamed styrene-based resin particles obtained by pre-foaming the expandable styrene-based resin particles according to any one of claims 1 to 6,
Pre-foamed styrene-based resin particles, wherein the volumetric expansion ratio of the pre-expansion is 1.6 times or more and less than 80 times. A styrene-based resin foam molded body molded from the expandable styrene-based resin particles according to any one of claims 1 to 6. A styrene-based resin foam molded body molded from the pre-expanded styrene-based resin particles of claim 7.

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