Foamable acrylonitrile-butadiene-styrene resin particles, acrylonitrile-butadiene-styrene foamed resin particles, and acrylonitrile-butadiene-styrene resin foamed molded article

Abstract

To provide foamable acrylonitrile-butadiene-styrene resin particles having superior foaming properties, acrylonitrile-butadiene-styrene foamed resin particles obtained by pre-foaming such foamable resin particles, and an acrylonitrile-butadiene-styrene resin foamed molded article molded from such foamable resin particles or foamed resin particles.SOLUTION: Foamable acrylonitrile-butadiene-styrene resin particles of the present invention contain an acrylonitrile-butadiene-styrene resin and a blowing agent, the acrylonitrile-butadiene-styrene resin having a melt flow rate of 5 g / 10 min to 15 g / 10 min under conditions of a temperature of 220°C and a load of 98 N, and having an expansion ratio SR(A / B) of 1.2 to 3.5, where A is an outer diameter of a resin strand and B is an inner diameter of an orifice at the time of the melt flow rate measurement.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to expandable acrylonitrile-butadiene-styrene resin particles, expandable acrylonitrile-butadiene-styrene resin particles, and foamed acrylonitrile-butadiene-styrene resin molded articles. [Background technology]

[0002] Foamed molded articles are widely used in various applications due to their light weight and excellent thermal insulation and mechanical strength. Among them, in-mold foamed molded articles produced from expandable resin particles are widely used due to their advantages such as the ease of obtaining a desired shape. Such foamed molded articles are composed of a plurality of expandable particles fused together.

[0003] Foamed molded articles of acrylonitrile-butadiene-styrene resin (ABS resin) are used as components for automobiles, home appliances, and the like. Methods for obtaining expandable ABS resin beads have been reported for producing in-mold foamed ABS resin articles (Patent Documents 1 to 3). However, the expandable ABS resin beads obtained by these methods do not have sufficient foaming properties for producing foamed molded articles. Furthermore, the foaming moldability deteriorates over time due to excessive cell miniaturization, resulting in a short storage period (bead life) and making them unsuitable for practical use. A method for producing expanded ABS resin beads has also been reported (Patent Document 4). However, because the beads are already expanded rather than expandable resin beads, they are bulky, which poses transportation problems, such as increased transportation costs and carbon dioxide emissions during transportation. Furthermore, the production process is complicated.

[0004] Furthermore, the amount of plastic waste is increasing year by year. While the majority of plastic waste is disposed of by incineration or landfilling, this has become a major social issue, resulting in environmental pollution, global warming, and a shortage of landfill sites. For this reason, there is a strong social demand for the reuse of plastic waste, and various approaches to recycling plastic waste have been considered, including the enforcement of the Home Appliance Recycling Law. While various recycling methods have been proposed, material recycling, in which plastic waste is reused as plastic components for products, has attracted attention from the perspectives of resource circulation and reducing environmental impact. However, recycled resin foam molded products molded using recycled expandable resin particles molded from recycled foam molded products generally have the problem of lower foam moldability and foam strength compared to resin foam molded products manufactured without using recycled raw materials. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2001-247709 [Patent Document 2] Japanese Patent Application Laid-Open No. 2007-211230 [Patent Document 3] Patent No. 4653321 [Patent Document 4] Japanese Unexamined Patent Publication No. 63-77947 Summary of the Invention [Problem to be solved by the invention]

[0006] The present invention has been made to solve the above-mentioned problems of the prior art, and its main object is to provide expandable acrylonitrile-butadiene-styrene resin particles having excellent expansion properties. It is also an object of the present invention to provide acrylonitrile-butadiene-styrene foamed resin particles obtained by pre-expanding such expandable acrylonitrile-butadiene-styrene resin particles. It is also an object of the present invention to provide an acrylonitrile-butadiene-styrene foamed resin molded article molded from such expandable acrylonitrile-butadiene-styrene resin particles or acrylonitrile-butadiene-styrene foamed resin particles. [Means for solving the problem]

[0007] [1] The expandable acrylonitrile-butadiene-styrene resin particles according to an embodiment of the present invention include an acrylonitrile-butadiene-styrene resin and a blowing agent, The acrylonitrile-butadiene-styrene resin has a melt flow rate of 5 g / 10 min to 15 g / 10 min under conditions of a temperature of 220°C and a load of 98 N, and an expansion ratio SR(A / B) between the outer diameter A of the resin strand and the inner diameter B of the orifice when measuring the melt flow rate is 1.2 to 3.5. [2] In the expandable acrylonitrile-butadiene-styrene resin particles described in [1] above, the acrylonitrile-butadiene-styrene resin may contain recycled acrylonitrile-butadiene-styrene resin. [3] In the expandable acrylonitrile-butadiene-styrene resin particles described in [2] above, the proportion of the recycled acrylonitrile-butadiene-styrene resin in the acrylonitrile-butadiene-styrene resin may be 50% by mass or more and 100% by mass or less. [4] The expandable acrylonitrile-butadiene-styrene-based resin particles according to any one of the above [1] to [3] may be obtained by pressurizing and impregnating the blowing agent into the acrylonitrile-butadiene-styrene-based resin particles (A) containing the acrylonitrile-butadiene-styrene-based resin. [5] In the expandable acrylonitrile-butadiene-styrene resin particles described in [4] above, the acrylonitrile-butadiene-styrene resin particles (A) may be obtained by adding a monomer component (b) containing a styrene monomer to a suspension containing resin raw material particles (a) containing the acrylonitrile-butadiene-styrene resin as a main component, and polymerizing the mixture in the presence of a polymerization initiator. [6] In the expandable acrylonitrile-butadiene-styrene resin particles described in [5] above, the resin raw material particles (a) may contain a low-molecular-weight polyolefin. [7] In the expandable acrylonitrile-butadiene-styrene resin particles described in [6] above, the amount of the low-molecular-weight polyolefin in the resin raw material particles (a) may be 0.05% by mass or more and 5% by mass or less. [8] In the expandable acrylonitrile-butadiene-styrene-based resin particles according to any one of [5] to [7] above, the ratio of the amount of the resin raw material particles (a) to the total amount of the resin raw material particles (a) and the monomer component (b) may be 50% by mass or more and 90% by mass or less. [9] The acrylonitrile-butadiene-styrene-based expanded resin particles according to an embodiment of the present invention are obtained by pre-expanding the expandable acrylonitrile-butadiene-styrene-based resin particles described in any one of [1] to [8] above.

[10] The acrylonitrile-butadiene-styrene resin foam molded article according to the embodiment of the present invention is molded from the acrylonitrile-butadiene-styrene resin foam particles described in [9] above.

[11] The acrylonitrile-butadiene-styrene resin foam molded article according to

[10] above has a density of 0.33 g / cm 3 It may be the following: [Effects of the Invention]

[0008] According to an embodiment of the present invention, it is possible to provide expandable acrylonitrile-butadiene-styrene-based resin particles having excellent expansion properties. It is also possible to provide acrylonitrile-butadiene-styrene-based expanded resin particles obtained by pre-expanding such expandable acrylonitrile-butadiene-styrene-based resin particles. Furthermore, it is also possible to provide an acrylonitrile-butadiene-styrene-based resin foam molded article molded from such expandable acrylonitrile-butadiene-styrene-based resin particles or acrylonitrile-butadiene-styrene-based expanded resin particles. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, embodiments of the present invention will be described, but the present invention is not limited to these embodiments.

[0010] In this specification, the expression "(meth)acrylic" means "acrylic and / or methacrylic", and the expression "(meth)acrylate" means "acrylate and / or methacrylate".

[0011] <<A. Expandable acrylonitrile-butadiene-styrene resin particles>> The expandable acrylonitrile-butadiene-styrene resin particles according to an embodiment of the present invention include an acrylonitrile-butadiene-styrene resin and a blowing agent. In this specification, the acrylonitrile-butadiene-styrene resin may be referred to as an "ABS resin."

[0012] In the expandable acrylonitrile-butadiene-styrene resin particles according to an embodiment of the present invention, the ABS resin serving as the base resin has a melt flow rate (MFR) of 3.0 g / 10 min to 15.0 g / 10 min, preferably 4.0 g / 10 min to 15.0 g / 10 min, and more preferably 5.0 g / 10 min to 15.0 g / 10 min, at a temperature of 220°C and a load of 98 N. If the MFR of the ABS resin is less than 3.0, a sufficient expansion ratio cannot be obtained. On the other hand, if the MFR of the ABS resin exceeds 15.0, the foam is prone to shrinkage, making it difficult to obtain a good foamed molded article.

[0013] In the expandable acrylonitrile-butadiene-styrene resin particles according to an embodiment of the present invention, the ABS resin as the base resin has an expansion ratio SR (A / B) between the outer diameter A of the resin strand and the inner diameter B of the orifice during the above-mentioned MFR measurement of 1.2 to 3.5, preferably 1.3 to 3.5, and more preferably 1.3 to 3.0. If the SR is less than 1.2, the foam tends to shrink. If the SR exceeds 3.5, a sufficient expansion ratio cannot be obtained. Here, the expansion ratio SR is the swell ratio (SR).

[0014] In the expandable acrylonitrile-butadiene-styrene resin particles, high expansion properties can be achieved by adjusting the MFR of the ABS resin within the range of 3.0 to 15.0 and the expansion ratio SR during MFR measurement within the range of 1.2 to 3.5. High expansion properties are, for example, represented by a high expansion ratio. The expansion ratio of the particles can be evaluated from the density of an acrylonitrile-butadiene-styrene resin foam molded from the expandable acrylonitrile-butadiene-styrene resin particles.

[0015] The bulk expansion ratio of the expandable acrylonitrile-butadiene-styrene resin particles is preferably 2.0 to 80.0 times, more preferably 3.0 to 70.0 times, and even more preferably 5.0 to 60.0 times.

[0016] The expandable acrylonitrile-butadiene-styrene resin particles have a particle shape as a whole. Any appropriate shape can be adopted as long as the effects of the present invention are not impaired. Specific examples of such shapes include a spherical shape, a nearly spherical shape, an oval spherical shape (egg-shaped), a cylindrical shape, and a nearly cylindrical shape.

[0017] The average particle size of the expandable acrylonitrile-butadiene-styrene resin particles is preferably 0.3 mm to 3.0 mm, more preferably 0.3 mm to 2.0 mm. The average particle size can be measured in accordance with JIS Z 8815. Specifically, the average particle size is the value measured as a particle size at 50% of the cumulative value from the particle size distribution according to the sieving test of JIS Z 8815.

[0018] ABS resins contain acrylonitrile-based monomers, butadiene-based monomers, and styrene-based monomers as monomer components constituting the ABS resins, i.e., they are resins obtained by polymerizing monomer components including acrylonitrile-based monomers, butadiene-based monomers, and styrene-based monomers.

[0019] In expandable acrylonitrile-butadiene-styrene resin particles (expandable ABS resin particles), the ABS resin may contain recycled ABS resin. The amount of recycled ABS resin relative to the total amount of ABS resin may be 50% or more, 70% or more, 85% or more, or 90% or more. The amount of recycled ABS resin may be, for example, 100% or less. The higher the above ratio, the higher the recycling rate of raw materials and the greater the environmental contribution. The expandable ABS resin particles according to an embodiment of the present invention can exhibit high expansion properties even when a high ratio of recycled materials is used.

[0020] The expandable ABS-based resin particles are obtained, for example, by injecting and impregnating a blowing agent into acrylonitrile-butadiene-styrene-based resin particles (A) containing an ABS-based resin (ABS-based resin particles (A)). The expandable ABS-based resin particles are preferably obtained by injecting and impregnating a blowing agent into ABS-based resin particles (A) obtained by adding a monomer component (b) to a suspension containing resin raw material particles (a) containing an ABS-based resin as the main component and polymerizing the resulting mixture in the presence of a polymerization initiator, in order to more effectively exhibit the effects of the present invention.

[0021] The main component is the component that is contained in the largest amount by mass in the resin raw material particles (a). The amount of ABS resin in the resin raw material particles (a) may be 50% or more, preferably 70% or more, more preferably 80% or more, even more preferably 90% or more, particularly preferably 95% or more, and most preferably 98% or more. The amount of ABS resin in the resin raw material particles (a) is, for example, 100% or less, preferably less than 100%, more preferably 99.5% or less.

[0022] The monomer component (b) preferably contains a styrene-based monomer.

[0023] When the ABS resin contains a recycled ABS resin, any appropriate recycled ABS resin can be used as the material for the resin raw material particles (a) as long as the effects of the present invention are not impaired. Examples of such recycled ABS resins include recycled products such as home appliance components, interior materials for automobiles, play equipment, and building materials.

[0024] The resin raw material particles (a) preferably contain a low-molecular-weight polyolefin. Specifically, the resin raw material particles (a) are preferably particles in which a low-molecular-weight polyolefin is kneaded into an ABS resin. Therefore, the expandable ABS resin particles preferably contain a low-molecular-weight polyolefin. By including a low-molecular-weight polyolefin, expandable acrylonitrile-butadiene-styrene resin particles can be realized that not only have high expansion properties but also have an excellent bead life. Therefore, even after storing the expandable ABS resin particles for a long period of time (e.g., 60 days or more), they can exhibit a high expansion ratio that is not significantly different from that immediately after production.

[0025] The amount of low-molecular-weight polyolefin in the resin raw material particles (a) is preferably 0.05% by mass or more and 5% by mass or less, more preferably 0.10% by mass or more and 3% by mass or less, and even more preferably 0.10% by mass or more and 2% by mass or less. This configuration can achieve a better bead life.

[0026] The low-molecular-weight polyolefin is, for example, an olefin wax having a molecular weight of 300 to 30,000 and a melting point of 40°C to 170°C. Examples of such olefin waxes include low-density polyethylene wax, high-density polyethylene wax, oxidized polyethylene wax, copolymerized polyethylene wax, polypropylene wax, paraffin wax, montan wax, and carnauba wax. These olefin waxes can be either linear or branched. Liquid paraffin can also be used as the low-molecular-weight polyolefin.

[0027] The resin raw material particles (a) are preferably pellets obtained by melt extrusion, which is a method in which a kneaded mixture of raw materials such as an ABS resin or a pulverized used ABS resin and a low-molecular-weight polyolefin is fed to a resin supplying device, melted in the resin supplying device, extruded through small holes in a die attached to the tip of the resin supplying device, and then cooled to obtain pellets.

[0028] The pellets obtained by the melt extrusion method are preferably at least one selected from extruded strand pellets obtained by extruding the kneaded material using an extruder and strand cutting the material; underwater cut pellets obtained by an underwater cutting method in which the kneaded material is extruded using an extruder and simultaneously cut in water; and hot cut pellets obtained by a hot cutting method in which the kneaded material is cut and cooled immediately after emerging from the die of the extruder.

[0029] As the resin raw material particles (a), the pellets obtained by the above-mentioned melt extrusion method may be used as they are, or they may be further melt extruded to form so-called "mini-pellets" in order to obtain smaller pellets.

[0030] The resin raw material particles (a) may contain any suitable resin other than the ABS resin, as long as the effects of the present invention are not impaired. Examples of such other resins include recycled resins such as styrene resins, AS resins, HIPS (high impact polystyrene); polyester resins such as polyethylene terephthalate (PET), polybutylene terephthalate (PBT), and polycarbonate (PC); polyamide resins such as nylon (PA); and polyolefin resins such as polyethylene (linear low-density polyethylene (LLDPE), low-density polyethylene (LDPE), and high-density polyethylene (HDPE)), polypropylene (PP), and EVA (ethylene-vinyl acetate copolymer). The other resins may be one type only, or two or more types may be used.

[0031] The resin raw material particles (a) may contain finely powdered inorganic and / or organic lubricants, which typically function as cell regulators.

[0032] Examples of finely powdered inorganic substances include talc, calcium carbonate, and silica. Here, talc typically refers to a mixture containing silicon oxide and magnesium oxide as main components and containing trace amounts of aluminum oxide, iron oxide, etc.

[0033] The average particle size of the finely powdered inorganic material is preferably 100 μm or less, and more preferably 30 μm or less.

[0034] The content of the fine powder inorganic material is preferably 0.1 to 5% by mass, and more preferably 0.5 to 2% by mass, relative to the resin raw material particles (a).

[0035] Examples of organic lubricants include polyethylene glycol; silicone oils such as dimethylpolysiloxane, methylphenylpolysiloxane, and methylhydrogenpolysiloxane; higher fatty acid bisatomids such as methylene bisstearylamide, ethylene bisstearylamide, and ethylene bisoleic acid amide; and metal salts of higher fatty acids such as zinc stearate, magnesium stearate, and zinc oleate.

[0036] The content of the organic lubricant relative to the resin raw material particles (a) is preferably 0.01% by mass to 2.0% by mass, more preferably 0.02% by mass to 1.8% by mass, and in some cases even more preferably 0.02% by mass to 0.2% by mass, and particularly preferably 0.02% by mass to 0.1% by mass.

[0037] A specific method for incorporating a fine powder inorganic substance and / or organic lubricant into the resin raw material particles (a) includes, for example, a method of kneading the fine powder inorganic substance and / or organic lubricant during extrusion molding. In this case, the kneaded mixture and a cell control agent are preferably mixed in advance, followed by extrusion molding. The kneaded mixture and the cell control agent can be mixed by any appropriate method as long as the effects of the present invention are not impaired. Examples of such methods include mixing using a mixer such as a tumbler, ribbon blender, V blender, Henschel mixer, or Redige mixer.

[0038] The resin raw material particles (a) are preferably heat-melted to adjust their specific gravity. In this process, the specific gravity of the resin raw material particles (a) is preferably adjusted to 0.6 or greater, more preferably 0.9 or greater. If the specific gravity of the resin raw material particles (a) is less than 0.6, the dispersion of the resin raw material particles (a) will be unstable, which may result in the generation of excessively large particles during the subsequent polymerization process, resulting in a reduced yield. The heat-melting of the resin raw material particles (a) can be carried out by any appropriate method as long as it does not impair the effects of the present invention. Examples of such methods include methods using an extruder or a heated roll. The heat-melting is preferably carried out by cooling and solidifying the resulting resin while leaving no or only minimal strain. If strain remains in the resin particles, the strain may be relaxed in the subsequent process, causing shrinkage in the stretching direction, resulting in the resulting expandable ABS resin particles becoming flat rather than spherical. Therefore, heat-melting without stretching using an extruder is preferred. If the resin is melted in a stretched state, distortion may remain in the stretched resin obtained after cooling and solidifying. However, even if distortion remains in the resin due to melting, it can be alleviated by curing the resin for a certain period of time at a temperature above its softening point.

[0039] For the pulverization to obtain the resin raw material particles (a), any pulverizer can be used as long as it does not impair the effects of the present invention. As such a pulverizer, for example, a pulverizer for plastics can be used, and a pulverizer for polystyrene is preferred.

[0040] The resin raw material particles (a) can be sieved as necessary and subjected to melting again using an extruder or the like.

[0041] The shape of the resin raw material particles (a) can be any appropriate shape as long as it is particulate, and examples thereof include cylindrical, spherical, approximately spherical, oval spherical (egg-shaped), etc. In reality, it is difficult to distinguish between spherical and approximately spherical, so in this specification, both are collectively referred to as spherical.

[0042] The average particle size of the resin raw material particles (a) is preferably 0.2 mm to 3.0 mm, more preferably 0.3 mm to 2.5 mm, even more preferably 0.4 mm to 2.0 mm, and particularly preferably 0.5 mm to 1.7 mm. If the average particle size of the resin raw material particles (a) exceeds 3 mm, the shape of the resulting expandable ABS resin particles may be difficult to achieve. If the average particle size of the resin raw material particles (a) is less than 0.2 mm, the average particle size of the resulting expandable ABS resin particles may be too small.

[0043] The L (long side) / D (short side) ratio of the resin raw material particles (a) is preferably 1.0 to 6.0, more preferably 1.0 to 5.0, even more preferably 1.0 to 4.0, particularly preferably 1.0 to 3.0, and most preferably 1.0 to 2.5. If the L (long side) / D (short side) ratio of the resin raw material particles (a) is outside the above range, the shape of the resulting expandable ABS resin particles may be difficult to achieve.

[0044] The resin raw material particles (a) preferably contain less than 1% by mass of particles having an average particle size of 200 μm or less. If the resin raw material particles (a) contain 1% by mass or more of particles having an average particle size of 200 μm or less, the appearance of the expandable ABS resin particles obtained using the resin raw material particles (a) may be deteriorated.

[0045] The MFR of the resin raw material particles (a) is not particularly limited, but is, for example, 10.0 g / 10 min to 40.0 g / 10 min, and preferably 10.0 g / 10 min to 30.0 g / 10 min.

[0046] The expansion ratio SR(A / B) of the outer diameter A of the resin strand to the inner diameter B of the orifice when measuring the MFR of the resin raw material particles (a) is not particularly limited, but is, for example, 1.2 or less, and preferably 1.3 or less.

[0047] In the expandable ABS-based resin particles according to an embodiment of the present invention, even if the resin raw material particles (a) used as the raw material have small MFR and SR, the MFR and SR of the ABS-based resin in the final expandable ABS-based resin particles can be within the above-mentioned ranges.

[0048] As mentioned above, the monomer component (b) preferably includes a styrene-based monomer.

[0049] The styrene-based monomer includes styrene or a styrene derivative. Examples of the styrene derivative include α-methylstyrene, vinyltoluene, chlorostyrene, ethylstyrene, i-propylstyrene, dimethylstyrene, and bromostyrene. The styrene-based monomer may be one type or two or more types. The styrene-based monomer preferably contains at least styrene. The content of styrene relative to the total amount of the styrene-based monomer is preferably 50% by mass or more, more preferably 70% by mass or more, even more preferably 90% by mass or more, and particularly preferably 95% by mass or more.

[0050] The monomer component (b) may further contain a polyfunctional monomer. The polyfunctional monomer may be one type only, or two or more types. The monomer component (b) does not necessarily contain a polyfunctional monomer.

[0051] The content ratio of the polyfunctional monomer to the styrene-based monomer is preferably 0.001 mass % to 0.049 mass %, more preferably 0.003 mass % to 0.045 mass %, even more preferably 0.005 mass % to 0.040 mass %, and particularly preferably 0.007 mass % to 0.035 mass %.

[0052] Specific examples of polyfunctional monomers include divinylbenzenes such as o-divinylbenzene, m-divinylbenzene, and p-divinylbenzene; and alkylene glycol di(meth)acrylates such as ethylene glycol di(meth)acrylate and polyethylene glycol di(meth)acrylate. Specific examples of (meth)acrylic acid ester monomers include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, butyl (meth)acrylate, pentyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, and hexyl (meth)acrylate. Specific examples of maleic acid ester monomers include dimethyl maleate. Specific examples of fumaric acid ester monomers include dimethyl fumarate, diethyl fumarate, and ethyl fumarate.

[0053] Among the polyfunctional monomers, divinylbenzene is preferred in that it can further exert the effects of the present invention. Note that divinylbenzene exists as three positional isomers, i.e., o-divinylbenzene, m-divinylbenzene, and p-divinylbenzene, and in the present invention, divinylbenzene consisting of any combination of these positional isomers can be used.

[0054] The polyfunctional monomer may be added to the suspension separately from the styrene-based monomer or together with the styrene-based monomer. When the polyfunctional monomer is added to the suspension together with the styrene-based monomer, the polyfunctional monomer is typically dissolved in the styrene-based monomer and added.

[0055] During polymerization, the suspension containing the resin raw material particles (a) may contain any suitable vinyl monomer other than the styrene monomer and the polyfunctional monomer. Such vinyl monomers may be one type only or two or more types. Examples of such vinyl monomers include (meth)acrylic acid ester monomers, maleic acid ester monomers, and fumaric acid ester monomers.

[0056] The vinyl monomer may be added to the suspension separately from the styrene-based monomer or together with the styrene-based monomer. When the vinyl monomer is added to the suspension together with the styrene-based monomer, the vinyl monomer is typically dissolved in the styrene-based monomer before addition.

[0057] The ratio of the amount of resin raw material particles (a) to the total amount of resin raw material particles (a) and monomer component (b) is preferably 50% by mass or more, more preferably 60% by mass or more, and even more preferably 70% by mass or more. This configuration further improves bead life. The upper limit of this ratio is, for example, 99% by mass or less, preferably 98% by mass or less, more preferably 95% by mass or less, even more preferably 94% by mass or less, particularly preferably 93% by mass or less, and most preferably 90% by mass or less. The ratio is preferably 50% by mass or more and 90% by mass or less.

[0058] When the ABS resin contains recycled ABS resin, the proportion of the recycled ABS resin relative to the total amount of the resin raw material particles (a) and the monomer component (b) is preferably 50% by mass or more, more preferably 60% by mass or more, and even more preferably 70% by mass or more. The upper limit of this proportion is, for example, 99% by mass or less, preferably 98% by mass or less, more preferably 95% by mass or less, even more preferably 94% by mass or less, particularly preferably 93% by mass or less, and most preferably 90% by mass or less. The higher this proportion, the higher the recycling rate of the raw materials and the greater the environmental contribution.

[0059] As described above, the ABS resin particles (A) are preferably obtained by adding the monomer component (b) to a suspension containing the resin raw material particles (a) and polymerizing the resulting mixture in the presence of a polymerization initiator. Any suitable polymerization method can be employed as long as it does not impair the effects of the present invention. A preferred embodiment of this polymerization method involves dispersing the resin raw material particles (a) as nuclei in an aqueous medium to obtain a suspension, to which the polymerization initiator and the monomer component (b) are added and polymerized.

[0060] When the resin raw material particles (a) are dispersed as nuclei in an aqueous medium to obtain a suspension, any suitable method can be adopted as the method for dispersing the resin raw material particles (a) in the aqueous medium as long as it does not impair the effects of the present invention. As such a dispersion method, dispersion using an apparatus equipped with a stirring blade is preferred.

[0061] When dispersing resin raw material particles (a) as nuclei in an aqueous medium to obtain a suspension, it is preferable to use a dispersant to disperse the resin raw material particles (a) in the aqueous medium. Any appropriate dispersant can be used as long as it can be used in suspension polymerization and does not impair the effects of the present invention. Examples of such dispersants include organic dispersants such as polyvinyl alcohol, polyvinylpyrrolidone, and methylcellulose; and sparingly soluble inorganic salts such as magnesium pyrophosphate and calcium triphosphate. Among these, magnesium pyrophosphate is preferred as the dispersant because it can better demonstrate the effects of the present invention.

[0062] The blending ratio of the dispersant relative to 100 parts by mass of the resin raw material particles (a) is preferably 0.1 to 2 parts by mass, more preferably 0.1 to 1.5 parts by mass, and even more preferably 0.1 to 1.0 part by mass.

[0063] When resin raw material particles (a) are dispersed as nuclei in an aqueous medium to obtain a suspension, it is preferable to use a surfactant to disperse the resin raw material particles (a) in the aqueous medium. Any appropriate surfactant that can be used in suspension polymerization can be used as long as it does not impair the effects of the present invention. Examples of such surfactants include sodium dodecylbenzenesulfonate, sodium alkanesulfonate, sodium alkylsulfonate, sodium alkyldiphenyletherdisulfonate, and sodium α-olefinsulfonate. Among these, sodium dodecylbenzenesulfonate is preferred as the surfactant, as it can further enhance the effects of the present invention.

[0064] The surfactant content per 100 parts by mass of the resin raw material particles (a) is preferably 0.005 to 0.1 parts by mass, more preferably 0.005 to 0.08 parts by mass, and even more preferably 0.005 to 0.06 parts by mass.

[0065] The polymerization initiator may be of only one type, or of two or more types.

[0066] The polymerization initiator is added, for example, by dissolving it in the monomer component (b) or a solvent, preferably by dissolving it in the styrene-based monomer. Examples of the solvent include aromatic hydrocarbons such as ethylbenzene and toluene; and aliphatic hydrocarbons such as heptane and octane. When a solvent is used, it is usually used in an amount of 10% by mass or less relative to the styrene-based monomer.

[0067] The polymerization initiator preferably contains a peroxyalkyl ester-based peroxide having a 10-hour half-life temperature of 65° C. or higher, in that the effects of the present invention can be more effectively exhibited.

[0068] Examples of peroxyalkyl ester peroxides having a 10-hour half-life temperature of 65°C or higher include 1,1,3,3-tetramethylbutylperoxy-2-ethylhexanoate (10-hour half-life temperature = 65.3°C), 2,5-dimethyl-2,5-di(2-ethylhexanoylperoxy)hexane (10-hour half-life temperature = 66.2°C), t-hexylperoxy-2-ethylhexanoate (10-hour half-life temperature = 69.9°C), t-butylperoxy-2-ethylhexanoate (10-hour half-life temperature = 72.1°C), and t-butylperoxybenzoate (10-hour half-life temperature = 104.3°C).

[0069] In addition to the compounds exemplified above, peroxyalkyl ester peroxides having a 10-hour half-life temperature of 65°C or higher include known compounds described in literature such as NOF Corporation's catalog "Organic Peroxides (10th Edition)."

[0070] The amount of peroxyalkyl ester peroxide having a 10-hour half-life temperature of 65°C or higher used is preferably 0.21% by mass to 4.50% by mass, more preferably 0.225% by mass to 3.00% by mass, even more preferably 0.240% by mass to 1.8% by mass, particularly preferably 0.27% by mass to 1.5% by mass, and most preferably 0.3% by mass to 1.2% by mass, relative to the styrene monomer in monomer component (b), in order to further exhibit the effects of the present invention.

[0071] The polymerization initiator preferably contains a peroxyalkyl ester peroxide having a 10-hour half-life temperature of 65° C. to 75° C., in order to further enhance the effects of the present invention. Examples of peroxyalkyl ester peroxides having a 10-hour half-life temperature of 65° C. to 75° C. include 1,1,3,3-tetramethylbutylperoxy-2-ethylhexanoate (10-hour half-life temperature = 65.3° C.), 2,5-dimethyl-2,5-di(2-ethylhexanoylperoxy)hexane (10-hour half-life temperature = 66.2° C.), t-hexylperoxy-2-ethylhexanoate (10-hour half-life temperature = 69.9° C.), and t-butylperoxy-2-ethylhexanoate (10-hour half-life temperature = 72.1° C.).

[0072] The amount of peroxyalkyl ester peroxide having a 10-hour half-life temperature of 65°C to 75°C used is preferably 0.070% by mass to 1.50% by mass, more preferably 0.075% by mass to 1.00% by mass, even more preferably 0.080% by mass to 0.60% by mass, particularly preferably 0.090% by mass to 0.50% by mass, and most preferably 0.1% by mass to 0.40% by mass, relative to the styrene monomer in monomer component (b).

[0073] As the polymerization initiator, a peroxyalkyl ester peroxide having a 10-hour half-life temperature of 65° C. to 75° C. and a peroxyalkyl ester peroxide having a 10-hour half-life temperature of 100° C. to 110° C. are preferably used in combination, in order to further enhance the effects of the present invention. An example of a peroxyalkyl ester peroxide having a 10-hour half-life temperature of 100° C. to 110° C. is t-butyl peroxybenzoate (10-hour half-life temperature: 104.3° C.).

[0074] The amount of peroxyalkyl ester peroxide having a 10-hour half-life temperature of 100°C to 110°C used is preferably 0.14% by mass to 3.0% by mass, more preferably 0.15% by mass to 2.00% by mass, even more preferably 0.16% by mass to 1.2% by mass, particularly preferably 0.18% by mass to 1.00% by mass, and most preferably 0.2% by mass to 0.80% by mass, relative to the styrene monomer in monomer component (b).

[0075] To obtain ABS resin particles (A), the addition temperature when adding the monomer component (b) to the suspension containing the resin raw material particles (a) is preferably 40° C. to 119° C., more preferably 40° C. to 118° C., even more preferably 40° C. to 117° C., particularly preferably 50° C. to 117° C., and most preferably 60° C. to 115° C., in order to further enhance the effects of the present invention. If the addition temperature when adding the styrene monomer to the suspension containing the resin raw material particles (a) is adjusted within the above range, the styrene monomer can be incorporated into the resin raw material particles (a) while maintaining an appropriate hardness, thereby achieving good spheroidization of the ABS resin particles (A), and thereby achieving good spheroidization and excellent moldability of the finally obtained expandable ABS resin particles. If the temperature at which the monomer component (b) is added to the resin raw material particles (a) is too low and outside the above range, the resin raw material particles (a) become too hard, and when the monomer component (b) (typically a styrene-based monomer) is incorporated in this state, the ABS resin particles (A) become difficult to spheroidize, which may result in the final expandable ABS resin particles being difficult to spheroidize and having poor moldability. If the temperature at which the styrene-based monomer is added to the resin raw material particles (a) is too high and outside the above range, the resin raw material particles (a) become too soft, and when the styrene-based monomer is incorporated in this state, the ABS resin particles (A) become difficult to spheroidize, which may result in the final expandable ABS resin particles being difficult to spheroidize and having poor moldability.

[0076] After the monomer component (b) is added to the suspension containing the resin raw material particles (a), the polymerization reaction may be continued at any appropriate temperature for any appropriate time, if necessary.

[0077] The suspension containing the resin raw material particles (a) may contain a cell regulator, such as fatty acid monoamides such as oleic acid amide, stearic acid amide, and hydroxystearic acid amide; and fatty acid bisamides such as methylene bisstearic acid amide and ethylene bisstearic acid amide.

[0078] As described above, the expandable ABS resin particles are obtained by pressurizing and impregnating the ABS resin particles (A) with a blowing agent.

[0079] A typical method for injecting and impregnating the blowing agent is to place the ABS resin particles (A) in a reactor such as an autoclave, and then inject and impregnate the blowing agent.

[0080] The foaming agent may be of one kind or two or more kinds.

[0081] Any suitable blowing agent can be used as long as it does not impair the effects of the present invention. The blowing agent referred to here is preferably a volatile blowing agent. The blowing agent is preferably an organic compound whose boiling point is equal to or lower than the softening point of the ABS resin and which is gaseous or liquid at normal pressure. Specific examples include aliphatic hydrocarbons such as propane, n-butane, isobutane, pentane (n-pentane, isopentane, 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; low-boiling ether compounds such as dimethyl ether, diethyl ether, dipropyl ether, and methyl ethyl ether; and halogen-containing hydrocarbons such as trichloromonofluoromethane and dichlorodifluoromethane. Inorganic gases such as carbon dioxide, nitrogen, and ammonia may also be used as the blowing agent. Among these, in terms of being able to further exhibit the effects of the present invention, the blowing agent is preferably at least one selected from n-butane, isobutane, n-pentane, isopentane, neopentane, cyclopentane, and cyclopentadiene, and more preferably at least one selected from n-butane, isobutane, n-pentane, and isopentane.

[0082] The content of the blowing agent can be appropriately set depending on the purpose, as long as it is an amount sufficient to form acrylonitrile-butadiene-styrene-based expanded resin particles (ABS-based expanded resin particles) and acrylonitrile-butadiene-styrene-based resin foamed molded articles (ABS-based resin foamed molded articles). The content of the blowing agent is preferably 2 to 15 parts by mass when the total amount of the resin raw material particles (a) and the styrene-based monomer in the monomer component (b) is taken as 100 parts by mass.

[0083] The temperature at which the blowing agent is injected into the ABS resin particles (A) is preferably 40°C to 150°C, more preferably 40°C to 140°C, even more preferably 40°C to 130°C, even more preferably 40°C to 123°C, even more preferably 40°C to 110°C, still more preferably 40°C to 105°C, particularly preferably 40°C to 95°C, and most preferably 40°C to 90°C. The temperature at which the blowing agent is injected into the ABS resin particles (A) may be varied within the above range. When the temperature at which the blowing agent is injected into the ABS resin particles (A) is within the above range, the blowing agent can be injected at a low temperature. Injecting the blowing agent at such a low temperature and then raising the temperature prevents the ABS resin particles (A) from being rapidly impregnated with the blowing agent, enabling uniform impregnation. For example, this can reduce areas that shrink and melt when molded into an ABS resin foam. If the temperature at which the blowing agent is injected into the ABS resin particles (A) is too low and outside the above range, the ABS resin particles (A) are not easily impregnated with the blowing agent during injection, and the blowing agent is rapidly impregnated when the temperature is raised, which may result in the ABS resin particles (A) not being uniformly impregnated with the blowing agent, which may easily cause uneven cell formation and surface shrinkage during molding. If the temperature at which the blowing agent is injected into the ABS resin particles (A) is too high and outside the above range, the blowing agent is rapidly impregnated into the ABS resin particles (A) during injection, which may result in the ABS resin particles (A) not being uniformly impregnated with the blowing agent, which may easily cause uneven cell formation and surface shrinkage during molding.

[0084] In one embodiment, the temperature for impregnating the ABS resin particles (A) with the blowing agent is preferably 40°C to 150°C, more preferably 40°C to 140°C, even more preferably 40°C to 130°C, even more preferably 40°C to 123°C, still more preferably 40°C to 110°C, particularly preferably 40°C to 105°C, and most preferably 40°C to 95°C.

[0085] Another embodiment of the impregnation temperature of the ABS resin particles (A) with the blowing agent is preferably a temperature equal to or higher than the temperature at which the blowing agent is injected into the ABS resin particles (A), and is preferably 93°C to 130°C, more preferably 94°C to 129°C, even more preferably 95°C to 128°C, particularly preferably 96°C to 127°C, and most preferably 97°C to 126°C.

[0086] The temperature for impregnating the ABS resin particles (A) with the blowing agent may be varied within the above range. When the impregnation temperature for the ABS resin particles (A) with the blowing agent falls within the above range, combined with the adjustment of the pressure-injection temperature, the ABS resin particles (A) are prevented from being rapidly impregnated with the blowing agent, enabling uniform impregnation. For example, this reduces the number of areas that shrink and melt during molding into an ABS resin foam. If the impregnation temperature for the ABS resin particles (A) is too low and outside the above range, the blowing agent may not penetrate all the way to the center of the ABS resin particles (A), leaving unfoamed areas, potentially preventing the production of a satisfactory molded product. If the impregnation temperature for the ABS resin particles (A) with the blowing agent is too high and outside the above range, the ABS resin particles (A) may be excessively impregnated with the blowing agent, potentially resulting in melting during molding.

[0087] The time for impregnating the ABS resin particles (A) with the blowing agent can be any appropriate time within the range that does not impair the effects of the present invention, and is preferably 1 to 10 hours.

[0088] The expandable ABS resin particles may contain any appropriate other component within the scope of not impairing the effects of the present invention, and such other component may be one kind or two or more kinds.

[0089] The expandable ABS resin particles may contain a flame retardant to enhance flame retardancy, and the flame retardant may be one kind or two or more kinds.

[0090] As the flame retardant, any appropriate flame retardant can be used as long as it does not impair the effects of the present invention. As such a flame retardant, a bromine compound compatible with polystyrene is preferred, and examples thereof include tetrabromoethane, tetrabromocyclooctane, hexabromocyclododecane, hexabromocyclohexane, trisdibromopropylphosphate, tetrabromobisphenol A, tetrabromobisphenol F, 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, 2,2-bis(4-allyloxy-3,5-dibromo)propane, and hexabromobenzene.

[0091] When a flame retardant is used, a flame retardant aid may be used in combination. Examples of the flame retardant aid include cumene hydroperoxide, dicumyl peroxide, t-butyl hydroperoxide, 2,3-dimethyl-2,3-diphenylbutane, and 3,4-dimethyl-3,4-diphenylhexane.

[0092] The total amount of the flame retardant and the flame retardant aid may be any appropriate amount within the range that does not impair the effects of the present invention, and is preferably 0.1 to 15% by mass, more preferably 0.2 to 10% by mass, even more preferably 0.2 to 5% by mass, and particularly preferably 0.2 to 3% by mass, based on the resin raw material particles (a).

[0093] The flame retardant may be added at any appropriate timing as long as the effects of the present invention are not impaired. The flame retardant is preferably added before the blowing agent is injected. By adding the flame retardant before the blowing agent is injected, the flame retardant can be added at a low temperature equivalent to the temperature at which the blowing agent is injected, which allows the resulting expandable ABS resin particles to be well spherical and to exhibit excellent moldability.

[0094] The temperature at which the flame retardant is added is preferably 5°C to 120°C, more preferably 5°C to 118°C, even more preferably 5°C to 115°C, even more preferably 5°C to 113°C, even more preferably 5°C to 110°C, even more preferably 40°C to 89°C, even more preferably 40°C to 87°C, even more preferably 40°C to 85°C, particularly preferably 40°C to 83°C, and most preferably 40°C to 80°C.

[0095] In producing expandable ABS-based resin particles, a partial ester of a higher fatty acid and an alcohol may be used as a cell control agent. That is, the expandable ABS-based resin particles may contain a partial ester of a higher fatty acid and an alcohol. The partial ester of a higher fatty acid and an alcohol may be one type or two or more types. Examples of higher fatty acids include fatty acids having 15 or more carbon atoms, such as palmitic acid, stearic acid, oleic acid, linoleic acid, linolenic acid, and behenic acid, and monoglycerides and diglycerides thereof can be used. Examples of the partial ester of a higher fatty acid and an alcohol include stearic acid monoglyceride and stearic acid diglyceride. The content of the partial ester of a higher fatty acid and an alcohol is preferably 0 to 3.0 parts by mass, more preferably 0.5 to 3.0 parts by mass, per 100 parts by mass of the ABS-based resin particles (A). The partial ester of a higher fatty acid and an alcohol may be added by, for example, adding it together with a blowing agent, or by a commonly used method such as a dry blending method, a masterbatch method, or a melt injection method.

[0096] A foaming aid may be used when producing expandable ABS-based resin particles. That is, the expandable ABS-based resin particles may contain a foaming aid. The foaming aid may be one type or two or more types. Examples of the foaming aid include diisobutyl adipate, toluene, cyclohexane, ethylbenzene, liquid paraffin, and coconut oil.

[0097] When producing expandable ABS-based resin particles, a cell-forming agent may be used. That is, the expandable ABS-based resin particles may contain a cell-forming agent. The cell-forming agent may be one type or two or more types. Examples of the cell-forming agent include fatty acid monoamides such as oleic acid amide, stearic acid amide, and hydroxystearic acid amide; and fatty acid bisamides such as methylene bisstearic acid amide and ethylene bisstearic acid amide.

[0098] The amount of the cell control agent used may be any appropriate amount within the range that does not impair the effects of the present invention, and is preferably 0 to 5.0 parts by mass, more preferably 0.02 to 3.0 parts by mass, even more preferably 0.02 to 2.0 parts by mass, and particularly preferably 0.02 to 1.0 part by mass, relative to 100 parts by mass of the ABS resin particles (A).

[0099] The expandable ABS resin particles may contain a cell regulator such as talc, calcium carbonate, mica, citric acid, sodium bicarbonate, etc. The cell regulator may be one type or two or more types.

[0100] In addition to the above, other additives include, for example, pigments, radiant heat transfer suppressing components, crosslinking agents, plasticizers, stabilizers, fillers, lubricants, colorants, antistatic agents, spreading agents, weather resistance agents, antioxidants, anti-fogging agents, and fragrances.

[0101] The expandable ABS resin particles may be surface-treated, preferably with at least one selected from silicone oil, antistatic agents, fatty acid metal salts, and fusion promoters.

[0102] When the surface treatment of the expandable ABS resin particles is performed with silicone oil, the amount of silicone oil used per 100 parts by mass of the expandable ABS resin particles before the surface treatment is preferably 0.001 to 0.3 parts by mass, more preferably 0.003 to 0.28 parts by mass, even more preferably 0.005 to 0.25 parts by mass, particularly preferably 0.008 to 0.23 parts by mass, and most preferably 0.01 to 0.23 parts by mass. If the amount of silicone oil used is too small outside the above range, for example, when an antistatic agent is used, the affinity with the antistatic agent may be insufficient during pre-foaming, which may result in the generation of static electricity. If the amount of silicone oil used is too large outside the above range, the surface may melt during molding, resulting in a loss of surface properties.

[0103] The silicone oil may be of one type only, or of two or more types.

[0104] As the silicone oil, any suitable silicone oil can be adopted as long as it does not impair the effects of the present invention.In terms of being able to further exhibit the effects of the present invention, as the silicone oil, for example, straight silicone oil such as dimethylpolysiloxane, methylphenylpolysiloxane, methylhydrogenpolysiloxane, etc. can be mentioned, and preferably methylphenylpolysiloxane.

[0105] When the expandable ABS resin particles are surface-treated with an antistatic agent, the amount of the antistatic agent used per 100 parts by mass of the expandable ABS resin particles before the surface treatment is preferably 0.001 to 0.3 parts by mass, more preferably 0.005 to 0.28 parts by mass, even more preferably 0.01 to 0.27 parts by mass, particularly preferably 0.015 to 0.26 parts by mass, and most preferably 0.02 to 0.25 parts by mass. If the amount of the antistatic agent is too small outside the above range, static electricity may be easily generated during pre-expansion. If the amount of the antistatic agent is too large outside the above range, the surface of the ABS resin foam particles or the ABS resin foam molded article may become sticky.

[0106] The antistatic agent may be of one type only, or may be of two or more types.

[0107] Any appropriate antistatic agent may be used as long as it does not impair the effects of the present invention. In order to further enhance the effects of the present invention, the antistatic agent may be at least one selected from a nonionic surfactant and a fatty acid glyceride, and preferably a combination of a nonionic surfactant and a fatty acid glyceride.

[0108] The nonionic surfactant may be one type only, or two or more types may be used.

[0109] As the nonionic surfactant, any appropriate nonionic surfactant may be used as long as it does not impair the effects of the present invention. Examples of nonionic surfactants that can further enhance the effects of the present invention include polyethylene glycol, glycerin, polyoxyethylene alkyl ethers, polyoxyethylene alkyl esters, polyhydric alcohols, and 1-amino-2-hydroxy compounds. Specific examples of polyoxyethylene alkyl ethers include polyoxyethylene cetyl ether, polyoxyethylene oleyl ether, and polyoxyethylene stearyl ether. Specific examples of polyoxyethylene alkyl esters include polyoxyethylene laurate, polyoxyethylene palmitate, polyoxyethylene stearate, and polyoxyethylene oleate. Specific examples of polyhydric alcohols include glycerin and propylene glycol. Specific examples of the 1-amino-2-hydroxy compound include N-hydroxyethyl-N-(2-hydroxyalkyl)amine, 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-hydroxypropyl-N N,N-bis(2-hydroxyethyl)dodecylamine, N,N-bis(2-hydroxyethyl)tetradecylamine, N,N-bis(2-hydroxyethyl)hexadecylamine, N,N-bis(2-hydroxyethyl)octadecylamine, and salts thereof.As the nonionic surfactant, polyethylene glycol is preferred in that it can more effectively exhibit the effects of the present invention.

[0110] When a nonionic surfactant is used as at least a part of the antistatic agent, the amount of the nonionic surfactant used per 100 parts by weight of the expandable ABS resin particles before surface treatment is preferably 0.001 to 2.0 parts by weight, more preferably 0.001 to 1.5 parts by weight, even more preferably 0.001 to 1.0 part by weight, even more preferably 0.001 to 0.5 parts by weight, even more preferably 0.001 to 0.3 parts by weight, even more preferably 0.005 to 0.28 parts by weight, even more preferably 0.01 to 0.27 parts by weight, particularly preferably 0.015 to 0.26 parts by weight, and most preferably 0.02 to 0.25 parts by weight. If the amount of nonionic surfactant is too small, outside the above range, static electricity may be easily generated during pre-expansion. If the amount of nonionic surfactant is too large and outside the above range, the surface of the ABS resin foam particles or the ABS resin foam molded article may become sticky.

[0111] The fatty acid glyceride may be one kind or two or more kinds.

[0112] As the fatty acid glyceride, any appropriate fatty acid glyceride can be used as long as it does not impair the effects of the present invention. Specific examples of the fatty acid glyceride that can further demonstrate the effects of the present invention include stearic acid monoglyceride and linoleic acid monoglyceride. As the fatty acid glyceride, stearic acid monoglyceride is preferred in terms of further demonstrating the effects of the present invention.

[0113] When a fatty acid glyceride is used as at least a part of the antistatic agent, the amount of the fatty acid glyceride relative to 100 parts by mass of the expandable ABS resin particles before surface treatment is preferably 0.001 to 0.3 parts by mass, more preferably 0.005 to 0.28 parts by mass, even more preferably 0.01 to 0.27 parts by mass, particularly preferably 0.015 to 0.26 parts by mass, and most preferably 0.02 to 0.25 parts by mass. If the amount of fatty acid glyceride is too small outside the above range, static electricity may be easily generated during pre-expansion. If the amount of fatty acid glyceride is too large outside the above range, the surface of the ABS resin particles or the ABS resin foam molded article may become sticky.

[0114] When the expandable ABS resin particles are surface-treated with a fatty acid metal salt, the amount of fatty acid metal salt used per 100 parts by mass of the expandable ABS resin particles before the surface treatment is preferably 0.005 to 0.5 parts by mass, more preferably 0.007 to 0.45 parts by mass, even more preferably 0.01 to 0.4 parts by mass, particularly preferably 0.015 to 0.35 parts by mass, and most preferably 0.02 to 0.3 parts by mass. If the amount of fatty acid metal salt is too small outside the above range, blocking may occur frequently during pre-expansion, making it difficult to obtain a good ABS resin foam molded article. If the amount of fatty acid metal salt is too large outside the above range, too much metal salt may be present during pre-expansion, which may increase the likelihood of electrification and static electricity generation, resulting in poor fusion of the molded article.

[0115] The fatty acid metal salt may be of one kind or of two or more kinds.

[0116] As the fatty acid metal salt, any appropriate fatty acid metal salt can be used as long as it does not impair the effects of the present invention. Examples of fatty acid metal salts that can further demonstrate the effects of the present invention include metal stearates and metal laurates. Specific examples of metal stearates include magnesium stearate, calcium stearate, zinc stearate, barium stearate, aluminum stearate, and lithium stearate. Specific examples of metal laurates include zinc laurate and barium laurate. As fatty acid metal salts, magnesium stearate and zinc stearate are preferred in terms of further demonstrating the effects of the present invention.

[0117] When the expandable ABS resin particles are surface-treated with a fusion accelerator, the amount of the fusion accelerator used per 100 parts by mass of the expandable ABS resin particles before the surface treatment is preferably 0.01 to 0.8 parts by mass, more preferably 0.01 to 0.7 parts by mass, even more preferably 0.01 to 0.6 parts by mass, particularly preferably 0.01 to 0.55 parts by mass, and most preferably 0.013 to 0.5 parts by mass. If the amount of the fusion accelerator is too small outside the above range, the fusion properties may decrease during molding, and a good ABS resin foam molded article may not be obtained. If the amount of the fusion accelerator is too large outside the above range, blocking may occur during pre-expansion.

[0118] The fusion promoter may be of one kind or two or more kinds.

[0119] Any appropriate fusion promoter may be used as the fusion promoter as long as it does not impair the effects of the present invention. Examples of fusion promoters that can further demonstrate the effects of the present invention include 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 vegetable oils include hydrogenated castor oil. Specific examples of stearic acid triglyceride and hydroxystearic acid triglyceride are preferred as fusion promoters in that they can further demonstrate the effects of the present invention.

[0120] <<B. Acrylonitrile-butadiene-styrene foam resin particles>> The acrylonitrile-butadiene-styrene-based expanded resin particles (ABS-based expanded resin particles) according to an embodiment of the present invention are obtained by pre-expanding the expandable ABS-based resin particles according to an embodiment of the present invention.

[0121] The ABS-based expanded resin particles preferably have an average cell diameter of 0.01 mm to 1.10 mm, more preferably 0.01 mm to 1.00 mm, even more preferably 0.01 to 0.90 mm, particularly preferably 0.01 mm to 0.80 mm, and most preferably 0.01 mm to 0.70 mm. When the average cell diameter of the ABS-based expanded resin particles is within the above range, blocking during expansion and molding can be more effectively prevented. Furthermore, the ABS-based expanded resin particles can exhibit better fusion properties and surface properties while further suppressing electrostatic charge during expansion and molding, thereby enabling the molding of ABS-based resin foam molded articles with less static electricity. If the average cell diameter of the ABS-based expanded resin particles is less than 0.01 mm, the surface may melt and shrink during molding.

[0122] Pre-expansion involves expanding the expandable ABS-based resin particles according to an embodiment of the present invention to a desired bulk expansion ratio (bulk density) using steam or the like. The bulk density of the ABS-based expandable resin particles is preferably 0.0125 g / cm. 3 ~0.33g / cm 3 or less, more preferably 0.0143 g / cm 3 ~0.20g / cm 3 or less, and more preferably 0.0166 g / cm 3 ~0.10g / cm 3 The bulk expansion ratio of the ABS-based expanded resin particles is preferably 3.0 to 80.0 times, more preferably 5.0 to 70.0 times, and even more preferably 10.0 to 60.0 times. When the bulk density of the ABS-based expanded resin particles is within the above range, blocking during expansion and molding can be more effectively prevented, and further, electrostatic charge during expansion and molding can be further suppressed while exhibiting better fusion properties and surface properties, making it possible to mold an ABS-based resin foam molded article with less static electricity.

[0123] In one representative embodiment, the ABS-based expanded resin particles according to an embodiment of the present invention can be used to form an ABS-based resin foam molded article. In another embodiment, the ABS-based expanded resin particles according to an embodiment of the present invention can be used as is as a cushioning material, a heat insulating material, a concrete aggregate, or the like. When the ABS-based expanded resin particles according to an embodiment of the present invention are used as is, they can preferably be used as a filler in which a large number of ABS-based expanded resin particles are filled into a bag. Such ABS-based expanded resin particles are suitable, for example, for the core material of a cushion (expanded particles filled inside the cushion).

[0124] The ABS-based expandable resin particles according to the embodiment of the present invention can be used as they are for producing an ABS-based resin foam molded article.

[0125] <<C. Acrylonitrile-butadiene-styrene resin foam molded body>> The acrylonitrile-butadiene-styrene-based resin foam molded article (ABS-based resin foam molded article) according to an embodiment of the present invention is an ABS-based resin foam molded article molded from the ABS-based resin foam particles according to an embodiment of the present invention.

[0126] ABS resin foam molded articles typically contain expanded ABS resin particles (hereinafter sometimes simply referred to as "expanded particles") obtained by further expanding ABS resin particles.

[0127] ABS resin foam molded articles are typically made up of a plurality of foam particles fused together.

[0128] The density of the ABS resin foam molded article according to the embodiment of the present invention is preferably 0.0125 g / cm 3 ~0.3g / cm 3 and more preferably 0.0143 g / cm 3 ~0.2g / cm 3 and more preferably 0.0166 g / cm 3 ~0.10g / cm 3 and particularly preferably 0.0166 g / cm 3 ~0.050g / cm 3 is.

[0129] ABS-based resin foam molded articles can typically be produced by placing ABS-based foam resin particles in a mold having a predetermined shape depending on the purpose and performing in-mold foam molding. More specifically, in-mold foam molding involves (i) filling ABS-based foam resin particles into a closed mold having many small holes, (ii) heating and expanding the ABS-based foam resin particles with a heat medium (e.g., pressurized steam) to obtain expanded particles, and (iii) filling the voids between the expanded particles and fusing the expanded particles together to form a single particle. The density of the ABS-based resin foam molded article can be appropriately set depending on the purpose. The density of the ABS-based resin foam molded article can be adjusted, for example, by adjusting the bulk expansion ratio of the ABS-based foam resin particles to be filled in the mold or by adjusting the amount of ABS-based foam resin particles filled in the mold.

[0130] The temperature of heat-induced foaming (substantially the temperature of the heat medium) is preferably 90°C to 150°C, more preferably 110°C to 130°C. The heat-induced foaming time is preferably 5 seconds to 50 seconds, more preferably 10 seconds to 50 seconds. The forming steam pressure of heat-induced foaming (the blowing gauge pressure of the heat medium) is preferably 0.04 MPa to 0.1 MPa, more preferably 0.06 MPa to 0.08 MPa. If the heat-induced foaming is under such conditions, the foamed particles can be well fused to each other.

[0131] If necessary, the ABS-based foamed resin particles may be aged before the formation of the ABS-based resin foamed molded body. The aging temperature of the ABS-based foamed resin particles is preferably 20°C to 60°C. If the aging temperature is too low, an excessively long aging time may be required. If the aging temperature is too high, the foaming agent in the ABS-based foamed resin particles may dissipate and the formability may decrease.

[0132] The ABS-based resin foamed molded body according to the embodiment of the present invention is lightweight, excellent in heat insulation and mechanical strength, and thus is suitably used for automobile interior materials, structural members, transport cushioning materials, heat insulation materials, filling materials, etc.

Examples

[0133] Hereinafter, the present invention will be specifically described by way of examples, but the present invention is not limited to these examples. The measurement methods and evaluation methods for each property are as follows.

[0134] <Measurement of the melt flow rate (MFR) and expansion ratio (SR) of the ABS-based resin> The MFR and SR of the ABS-based resin were measured in accordance with JIS K-7210 at 220°C under a load of 98 N. The SR was calculated by the following method. In accordance with JIS K-7210, an ABS resin was extruded from an orifice with an inner diameter B of 2.09 mm at 220 °C under a load of 98 N, and the MFR was measured. When the extrusion direction of the resin strand obtained at this time was taken as the tip, the outer diameters at five arbitrary positions were measured in the portion 5 mm to 20 mm in the direction opposite to the extrusion direction from the tip, and the average value of these outer diameters was defined as the outer diameter A (mm). Next, with the expansion ratio of the outer diameter A to the inner diameter B of the orifice of 2.09 mm being SR, SR was calculated by the following calculation formula and obtained to the second decimal place. SR = outer diameter A (mm) / 2.09 (mm)

[0135] <Measurement of bulk density of ABS foamed resin particles> The bulk density of the ABS foamed resin particles was measured as follows. After allowing the ABS foamed resin particles to fall naturally into a graduated cylinder as a sample, the bottom of the graduated cylinder was tapped to make the sample volume constant, and the volume and mass were measured and calculated by the following formula. Bulk density (g / cm 3 ) = sample mass (g) / sample volume in graduated cylinder (cm 3 )

[0136] <Measurement of density of ABS resin foamed molded article> The density of the ABS resin foamed molded article was measured such that the dimensions and mass of the test piece had three or more significant figures, and calculated by the following formula. Density (g / cm 3 ) = test piece mass (g) / test piece volume (cm 3 )

[0137] <Evaluation of foam molding property> Using the density of the ABS resin foamed molded article formed from the ABS foamed resin particles obtained by pre-foaming the foaming ABS resin particles, evaluation was performed according to the following criteria. ◎: The density of the foamed molded article is 0.05 g / cm 3 or less. 〇: The density of the foamed molded article is greater than 0.05 g / cm 3 and less than or equal to 0.1 g / cm 3 . ×: Density of foamed molded article is 0.1 g / cm 3 Greater than.

[0138] <Evaluation of bead life of expandable ABS resin particles> For expandable ABS-based resin particles that were evaluated as ⊚ or ◯ in the foam moldability evaluation, a storage test was conducted by leaving the expanded ABS-based resin particles for a period X (maximum 90 days) under normal pressure (1 atmosphere) and a temperature of 15°C after production. The expandability was evaluated for each of the particles immediately after production and after the storage test. To evaluate the expandability, the expandable ABS-based resin particles were pre-expanded by the method described in Example 1 below to obtain ABS-based expanded resin particles, and then the density of an ABS-based resin foam molded article molded by the method described in Example 1 below was measured. The ratio R of the density of the foam molded article using the expandable ABS-based resin particles after the storage test to the density of the foam molded article using the expandable ABS-based resin particles immediately after production was calculated using the following formula. Ratio R (%) = 100 × (density of foam molded product using particles after storage test for period X) / (density of foam molded product using particles immediately after production) The bead life was evaluated according to the following criteria based on the maximum number of days during the period X during which the ratio R [%] was 90% or more. ◎: 90 days 〇: 30 days or more but less than 90 days △: Less than 30 days

[0139] [Example 1] Acrylonitrile-butadiene-styrene resin (recycled acrylonitrile-butadiene-styrene resin) used as a component for home appliances was fed into an extruder and melted at a resin temperature of 225°C. 1% by mass of polyethylene wax (molecular weight 1000) was mixed into the resin and extruded into strands. The strands were then cut into 0.8 mm average diameter, 0.9 mm length pieces to obtain resin raw material particles (a). The MFR of resin raw material particles (a) was 17.2 g / 10 min and the SR was 1.1. Next, 2000 parts by mass of water, 1400 parts by mass of resin raw material particles (a), 6 parts by mass of magnesium pyrophosphate, and 0.3 parts by mass of calcium dodecylbenzenesulfonate were supplied to a pressure-resistant polymerization vessel equipped with a stirrer, and the mixture was heated to 60°C with stirring to prepare a dispersion. Next, 0.9 parts by mass of t-butylperoxy-2-ethylhexanoate and 1.8 parts by mass of t-butylperoxybenzoate were dissolved in 600 parts by mass of styrene monomer, and this styrene monomer solution was all fed into the above dispersion while stirring. 30 minutes after the feed, the temperature was raised to 90°C and polymerization was carried out for 4 hours to grow seed particles of the acrylonitrile-butadiene-styrene resin raw material. Further, the temperature was raised to 125°C and maintained at this temperature for 2 hours to carry out polymerization, yielding acrylonitrile-butadiene-styrene resin particles (A). A portion of the resulting acrylonitrile-butadiene-styrene resin particles (A) was taken out and the MFR and other properties were measured, and the MFR was 9.5 g / 10 min and the SR was 1.45. Subsequently, the temperature was cooled to 90°C, and 180 parts by mass of pentane was injected into the polymerization vessel and maintained for 6 hours to impregnate the acrylonitrile-butadiene-styrene resin particles (A) with pentane. Thereafter, the temperature inside the polymerization vessel was cooled to 30°C to obtain expandable acrylonitrile-butadiene-styrene resin particles (p1).

[0140] After coating the surfaces of the expandable acrylonitrile-butadiene-styrene resin particles (p1) with polyethylene glycol as an antistatic agent, zinc stearate and hydroxystearic acid triglyceride were coated on the surfaces of the expandable acrylonitrile-butadiene-styrene resin particles (p1). The zinc stearate and hydroxystearic acid triglyceride were each adjusted to 0.05% by mass in the expandable acrylonitrile-butadiene-styrene resin particles (p1). The expandable acrylonitrile-butadiene-styrene resin particles were then left in a thermostatic chamber at 13°C for 5 days. The pentane content in the expandable acrylonitrile-butadiene-styrene resin particles (p1) after the exposure was measured by gas chromatography and found to be 6.3% by mass.

[0141] Thereafter, the expandable acrylonitrile-butadiene-styrene resin particles (p1) were heated to a bulk density of 0.02 g / cm 3 The acrylonitrile-butadiene-styrene foamed resin particles (pf1) were then pre-expanded at 20°C for 24 hours.

[0142] Next, the acrylonitrile-butadiene-styrene type foamed resin particles (pf1) were filled into a mold and heated to foam, to obtain a plate-shaped acrylonitrile-butadiene-styrene type foamed resin molded product (1) having a length of 400 mm, a width of 300 mm, and a thickness of 30 mm. The acrylonitrile-butadiene-styrene type foamed resin molded product (1) was aged for 6 hours in a drying chamber at 50°C, and then its density was measured and found to be 0.02 g / cm. 3 The acrylonitrile-butadiene-styrene resin foam molded article (1) had no shrinkage and excellent appearance. The flexural strength of the obtained acrylonitrile-butadiene-styrene resin foam molded article (1) was 0.45 MPa, which was excellent.

[0143] Furthermore, a storage test was carried out on the expandable acrylonitrile-butadiene-styrene resin particles (p1) in an atmosphere at 15°C, and the resin particles after the storage test were used to mold an acrylonitrile-butadiene-styrene resin foam molded article in the same manner as above, to confirm the change in foam moldability over time. As a result, even after a 90-day storage test, the density was 0.02 g / cm 3 The foamed molded article exhibited good foam moldability.

[0144] [Example 2] The same procedure as in Example 1 was carried out, except that the amount of resin raw material particles (a) in the dispersion was changed to 1600 parts by mass, and 0.6 parts by mass of t-butylperoxy-2-ethylhexanoate and 1.2 parts by mass of t-butylperoxybenzoate were dissolved in 400 parts by mass of styrene monomer. Expandable acrylonitrile-butadiene-styrene resin particles (p2), acrylonitrile-butadiene-styrene resin expanded particles (pf2), and acrylonitrile-butadiene-styrene resin foam molded articles (2) were obtained. The MFR of the ABS resin (acrylonitrile-butadiene-styrene resin particles (A)) in the expandable acrylonitrile-butadiene-styrene resin particles (p2) was 12.0 g / 10 min, and the SR was 1.35. The density of the acrylonitrile-butadiene-styrene resin foam molded article (2) was 0.02 g / cm. 3 As in Example 1, the change in foam moldability over time was checked, and it was found that the density was 0.02 g / cm even after a 90-day storage test. 3 The flexural strength of the obtained acrylonitrile-butadiene-styrene resin foam molded article (2) was 0.43 MPa, which was excellent.

[0145] [Example 3] The same procedure as in Example 1 was carried out, except that the amount of resin raw material particles (a) in the dispersion was changed to 1,200 parts by mass, and 1.2 parts by mass of t-butylperoxy-2-ethylhexanoate and 2.4 parts by mass of t-butylperoxybenzoate were dissolved in 800 parts by mass of styrene monomer. Expandable acrylonitrile-butadiene-styrene resin particles (p3), acrylonitrile-butadiene-styrene expanded resin particles (pf3), and acrylonitrile-butadiene-styrene resin foam molded articles (3) were obtained. The MFR of the ABS resin (acrylonitrile-butadiene-styrene resin particles (A)) in the expandable acrylonitrile-butadiene-styrene resin particles (p3) was 9.2 g / 10 min, and the SR was 1.45. The density of the acrylonitrile-butadiene-styrene resin foam molded article (3) was 0.02 g / cm. 3As in Example 1, the change in foam moldability over time was checked, and it was found that the density was 0.02 g / cm even after a 90-day storage test. 3 The flexural strength of the obtained acrylonitrile-butadiene-styrene resin foam molded article (3) was 0.47 MPa, which was excellent.

[0146] [Example 4] The same procedure as in Example 1 was carried out, except that the amount of resin raw material particles (a) in the dispersion was changed to 1,000 parts by mass, and 1.5 parts by mass of t-butylperoxy-2-ethylhexanoate and 3.0 parts by mass of t-butylperoxybenzoate were dissolved in 1,000 parts by mass of styrene monomer. Expandable acrylonitrile-butadiene-styrene resin particles (p4), acrylonitrile-butadiene-styrene resin expanded particles (pf4), and acrylonitrile-butadiene-styrene resin foam molded articles (4) were obtained. The MFR of the ABS resin (acrylonitrile-butadiene-styrene resin particles (A)) in the expandable acrylonitrile-butadiene-styrene resin particles (p4) was 7.0 g / 10 min, and the SR was 2.85. The density of the acrylonitrile-butadiene-styrene resin foam molded article (4) was 0.02 g / cm. 3 As in Example 1, the change in foam moldability over time was checked, and after a 90-day storage test, the density was 0.02 g / cm 3 The resulting acrylonitrile-butadiene-styrene resin foam molded article (4) had an excellent bending strength of 0.48 MPa.

[0147] [Example 5] The same procedure as in Example 1 was repeated, except that instead of dissolving 0.9 parts by weight of t-butylperoxy-2-ethylhexanoate and 1.8 parts by weight of t-butylperoxybenzoate in 600 parts by weight of styrene monomer, 0.6 parts by weight of t-butylperoxy-2-ethylhexanoate and 1.2 parts by weight of t-butylperoxybenzoate were dissolved in 600 parts by weight of styrene monomer. Expandable acrylonitrile-butadiene-styrene resin particles (p5), acrylonitrile-butadiene-styrene resin foam particles (pf5), ​​and acrylonitrile-butadiene-styrene resin foam molded articles (5) were obtained. The MFR of the ABS resin (acrylonitrile-butadiene-styrene resin particles (A)) in the expandable acrylonitrile-butadiene-styrene resin particles (p5) was 9.0 g / 10 min, and the SR was 2.50. The density of the acrylonitrile-butadiene-styrene resin foam molded body (5) is 0.02 g / cm 3 As in Example 1, the change in foam moldability over time was checked, and it was found that the density was 0.02 g / cm even after a 90-day storage test. 3 The flexural strength of the obtained acrylonitrile-butadiene-styrene resin foam molded article (5) was 0.46 MPa, which was excellent.

[0148] [Example 6] The same procedure as in Example 1 was repeated, except that instead of dissolving 0.9 parts by mass of t-butylperoxy-2-ethylhexanoate and 1.8 parts by mass of t-butylperoxybenzoate in 600 parts by mass of styrene monomer, 1.2 parts by mass of t-butylperoxy-2-ethylhexanoate and 2.4 parts by mass of t-butylperoxybenzoate were dissolved in 600 parts by mass of styrene monomer. Expandable acrylonitrile-butadiene-styrene resin particles (p6), acrylonitrile-butadiene-styrene resin foam particles (pf6), and acrylonitrile-butadiene-styrene resin foam molded articles (6) were obtained. The MFR of the ABS resin (acrylonitrile-butadiene-styrene resin particles (A)) in the expandable acrylonitrile-butadiene-styrene resin particles (p6) was 9.9 g / 10 min, and the SR was 1.38. The density of the acrylonitrile-butadiene-styrene resin foam molded body (6) is 0.02 g / cm 3 As in Example 1, the change in foam moldability over time was checked, and it was found that the density was 0.02 g / cm even after a 90-day storage test. 3 The flexural strength of the obtained acrylonitrile-butadiene-styrene resin foam molded article (6) was 0.46 MPa, which was excellent.

[0149] [Example 7] In the preparation of resin raw material particles (a), the amount of polyethylene wax (molecular weight 1000) added to the acrylonitrile-butadiene-styrene resin was changed to 0.5% by mass. The same procedure as in Example 1 was carried out to obtain expandable acrylonitrile-butadiene-styrene resin particles (p7), acrylonitrile-butadiene-styrene expanded resin particles (pf7), and acrylonitrile-butadiene-styrene resin foam molded articles (7). The MFR of the ABS resin (acrylonitrile-butadiene-styrene resin particles (A)) in the expandable acrylonitrile-butadiene-styrene resin particles (p7) was 9.4 g / 10 min, and the SR was 1.46. The density of the acrylonitrile-butadiene-styrene resin foam molded article (7) was 0.02 g / cm. 3As in Example 1, the change in foam moldability over time was checked, and it was found that the density was 0.02 g / cm even after a 90-day storage test. 3 The flexural strength of the obtained acrylonitrile-butadiene-styrene resin foam molded article (7) was 0.45 MPa, which was excellent.

[0150] [Example 8] In the preparation of resin raw material particles (a), the amount of polyethylene wax (molecular weight 1000) added to the acrylonitrile-butadiene-styrene resin was changed to 2.0 mass %. The same procedure as in Example 1 was carried out to obtain expandable acrylonitrile-butadiene-styrene resin particles (p8), acrylonitrile-butadiene-styrene expanded resin particles (pf8), and acrylonitrile-butadiene-styrene resin foam molded article (8). The MFR of the ABS resin (acrylonitrile-butadiene-styrene resin particles (A)) in the expandable acrylonitrile-butadiene-styrene resin particles (p8) was 9.7 g / 10 min, and the SR was 1.44. The density of the acrylonitrile-butadiene-styrene resin foam molded article (8) was 0.02 g / cm. 3 As in Example 1, the change in foam moldability over time was checked, and it was found that the density was 0.02 g / cm even after a 90-day storage test. 3 The flexural strength of the obtained acrylonitrile-butadiene-styrene resin foam molded article (8) was 0.45 MPa, which was excellent.

[0151] [Example 9] In the preparation of resin raw material particles (a), the procedure was carried out in the same manner as in Example 1, except that virgin acrylonitrile-butadiene-styrene resin with an MFR of 20.0 g / 10 min and an SR of 1.11 was used instead of the recycled acrylonitrile-butadiene-styrene resin, which was a recovered product. Expandable acrylonitrile-butadiene-styrene resin particles (p9), acrylonitrile-butadiene-styrene resin expanded particles (pf9), and acrylonitrile-butadiene-styrene resin foam molded articles (9) were obtained. The MFR of the ABS resin (acrylonitrile-butadiene-styrene resin particles (A)) in the expandable acrylonitrile-butadiene-styrene resin particles (p9) was 10.0 g / 10 min and the SR was 1.39. The density of the acrylonitrile-butadiene-styrene resin foam molded article (9) was 0.02 g / cm. 3 As in Example 1, the change in foam moldability over time was checked, and it was found that the density was 0.02 g / cm even after a 90-day storage test. 3 The flexural strength of the obtained acrylonitrile-butadiene-styrene resin foam molded article (9) was 0.47 MPa, which was excellent.

[0152] [Example 10] The same procedure as in Example 1 was carried out except that polyethylene wax (molecular weight 1000) was not added in the preparation of resin raw material particles (a), and expandable acrylonitrile-butadiene-styrene resin particles (p10), acrylonitrile-butadiene-styrene expanded resin particles (pf9), and acrylonitrile-butadiene-styrene resin foam molded article (10) were obtained. The MFR of the ABS resin (acrylonitrile-butadiene-styrene resin particles (A)) in the expandable acrylonitrile-butadiene-styrene resin particles (p10) was 9.2 g / 10 min, and the SR was 1.48. The density of the acrylonitrile-butadiene-styrene resin foam molded article (10) was 0.02 g / cm 3As in Example 1, the change in foam moldability over time was checked, and it was found that the foam moldability had decreased after a 14-day storage test. The flexural strength of the obtained acrylonitrile-butadiene-styrene resin foam molded article (10) was excellent at 0.44 MPa.

[0153] [Example 11] In the preparation of resin raw material particles (a), the amount of polyethylene wax (molecular weight 1000) added to the acrylonitrile-butadiene-styrene resin was changed to 0.3 mass %. The same procedure as in Example 1 was carried out to obtain expandable acrylonitrile-butadiene-styrene resin particles (p11), acrylonitrile-butadiene-styrene expanded resin particles (pf11), and acrylonitrile-butadiene-styrene resin foam molded article (11). The MFR of the ABS resin (acrylonitrile-butadiene-styrene resin particles (A)) in the expandable acrylonitrile-butadiene-styrene resin particles (p11) was 9.2 g / 10 min, and the SR was 1.45. The density of the acrylonitrile-butadiene-styrene resin foam molded article (11) was 0.02 g / cm 3 As in Example 1, the change in foam moldability over time was checked, and it was found that the foam moldability had decreased after a 30-day storage test. The flexural strength of the obtained acrylonitrile-butadiene-styrene resin foam molded article (11) was 0.44 MPa, which was excellent.

[0154] [Comparative Example 1] The procedure of Example 1 was repeated, except that instead of dissolving 0.9 parts by mass of t-butylperoxy-2-ethylhexanoate and 1.8 parts by mass of t-butylperoxybenzoate in 600 parts by mass of styrene monomer, 0.9 parts by mass of benzoyl peroxide and 1.8 parts by mass of t-butylperoxybenzoate were dissolved in 600 parts by mass of styrene monomer. Expandable acrylonitrile-butadiene-styrene resin particles (pC1), acrylonitrile-butadiene-styrene resin expandable particles (pfC1), and acrylonitrile-butadiene-styrene resin foam molded articles (C1) were obtained. The MFR of the ABS resin (acrylonitrile-butadiene-styrene resin particles (A)) in the expandable acrylonitrile-butadiene-styrene resin particles (pC1) was 18.3 g / 10 min, and the SR was 1.12. The density of the foam molded article (C1) was 0.6 g / cm. 3 As a result, a good foamed molded article was not obtained.

[0155] Comparative Example 2 Expandable acrylonitrile-butadiene-styrene resin particles (pC2) were obtained in the same manner as in Example 1, except that instead of dissolving 0.9 parts by mass of t-butylperoxy-2-ethylhexanoate and 1.8 parts by mass of t-butylperoxybenzoate in 600 parts by mass of styrene monomer, 0.4 parts by mass of t-butylperoxy-2-ethylhexanoate and 0.8 parts by mass of t-butylperoxybenzoate were dissolved in 600 parts by mass of styrene monomer, and the polymerization time at 90°C was changed to 8 hours. The MFR of the ABS resin (acrylonitrile-butadiene-styrene resin particles (A)) in the expandable acrylonitrile-butadiene-styrene resin particles (pC2) was 1.2 g / 10 min and SR was 3.82. The density of the expanded molded product (C2) was 0.7 g / cm 3 As a result, a good foamed molded article was not obtained.

[0156] Comparative Example 3 Expandable acrylonitrile-butadiene-styrene-based resin particles (pC3) were obtained in the same manner as in Example 1, except that in the preparation of resin raw material particles (a), polyethylene wax (molecular weight 1000) was not added, the amount of resin raw material particles (a) was 2000 parts by mass, and further, the resin raw material particles (a) were impregnated with pentane without undergoing polymerization while adding a styrene monomer solution (preparation of acrylonitrile-butadiene-styrene-based resin particles (A)). That is, in Comparative Example 3, 2000 parts by mass of water, 2000 parts by mass of resin raw material particles (a) made of recycled acrylonitrile-butadiene-styrene resin, 6 parts by mass of magnesium pyrophosphate, and 0.3 parts by mass of calcium dodecylbenzenesulfonate were stirred at 60 ° C in a pressure-resistant polymerization vessel equipped with a stirrer to obtain a dispersion, and then 180 parts by mass of pentane was pressure-charged into the polymerization vessel at 90 ° C and held for 6 hours to impregnate the resin raw material particles (a) with pentane, and then the polymerization vessel was cooled to 30 ° C to obtain expandable acrylonitrile-butadiene-styrene resin particles (pC3). Polyethylene glycol, zinc stearate, and hydroxystearic acid triglyceride were applied to the surface in the same manner as in Example 1, and after leaving it in a thermostatic chamber at 13 ° C for 5 days, the pentane content was measured by gas chromatography and found to be 6.5% by mass. This was pre-expanded in the same manner as in Example 1, and the bulk density was 0.10 g / cm. 3 The pre-expanded particles were aged at 20°C for 24 hours, and then filled into a mold to attempt to form a foamed molded article by heating and expanding, but no foamed molded article was obtained.

[0157] [Table 1]

[0158] The expandable acrylonitrile-butadiene-styrene resin particles of Examples 1 to 11 had good expansion moldability. Furthermore, Examples 1 to 9 also had good bead life.

[0159] The expandable acrylonitrile-butadiene-styrene resin particles, the expandable acrylonitrile-butadiene-styrene resin particles, and the acrylonitrile-butadiene-styrene resin foamed molded articles according to the embodiments of the present invention can be used in a wide range of applications, such as daily necessities, automobile parts, electrical appliances, and industrial parts.

Claims

1. Contains an acrylonitrile-butadiene-styrene resin and a blowing agent, The acrylonitrile-butadiene-styrene-based resin has a melt flow rate of 5 g / 10 min to 15 g / 10 min under conditions of a temperature of 220°C and a load of 98 N, and an expansion ratio SR(A / B) of an outer diameter A of a resin strand to an inner diameter B of an orifice at the time of measuring the melt flow rate is 1.2 to 3.

5.

2. 2. The expandable acrylonitrile-butadiene-styrene based resin particles according to claim 1, wherein the acrylonitrile-butadiene-styrene based resin comprises recycled acrylonitrile-butadiene-styrene based resin.

3. 3. The expandable acrylonitrile-butadiene-styrene resin particles according to claim 2, wherein the proportion of the amount of the recycled acrylonitrile-butadiene-styrene resin in the acrylonitrile-butadiene-styrene resin is 50% by mass or more and 100% by mass or less.

4. The expandable acrylonitrile-butadiene-styrene type resin particles according to claim 1, which are obtained by pressurizing and impregnating the blowing agent into acrylonitrile-butadiene-styrene type resin particles (A) containing the acrylonitrile-butadiene-styrene type resin.

5. The expandable acrylonitrile-butadiene-styrene type resin particles according to claim 4, wherein the acrylonitrile-butadiene-styrene type resin particles (A) are obtained by adding a monomer component (b) containing a styrene type monomer to a suspension containing resin raw material particles (a) containing the acrylonitrile-butadiene-styrene type resin as a main component, and polymerizing the mixture in the presence of a polymerization initiator.

6. The expandable acrylonitrile-butadiene-styrene resin particles according to claim 5, wherein the resin raw material particles (a) contain a low-molecular-weight polyolefin.

7. The expandable acrylonitrile-butadiene-styrene resin particles according to claim 6, wherein the amount of the low-molecular-weight polyolefin in the resin raw material particles (a) is 0.05% by mass or more and 5% by mass or less.

8. 6. The expandable acrylonitrile-butadiene-styrene-based resin particles according to claim 5, wherein the ratio of the amount of the resin raw material particles (a) to the total amount of the resin raw material particles (a) and the monomer component (b) is 50% by mass or more and 90% by mass or less.

9. 9. Expanded acrylonitrile-butadiene-styrene resin particles obtained by pre-expanding the expandable acrylonitrile-butadiene-styrene resin particles according to claim 1.

10. An acrylonitrile-butadiene-styrene resin foam molded article molded from the acrylonitrile-butadiene-styrene resin foam particles according to claim 9.

11. Density is 0.33 g / cm 3 The acrylonitrile-butadiene-styrene resin foam molded article according to claim 10, which is as follows:

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