JP2007246606A - Expandable polystyrene resin particle, expanded polystyrene resin particle, molded article of expanded polystyrene resin, sliced article of expanded polystyrene resin, and method for preparation of the same - Google Patents

Expandable polystyrene resin particle, expanded polystyrene resin particle, molded article of expanded polystyrene resin, sliced article of expanded polystyrene resin, and method for preparation of the same Download PDF

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JP2007246606A
JP2007246606A JP2006069164A JP2006069164A JP2007246606A JP 2007246606 A JP2007246606 A JP 2007246606A JP 2006069164 A JP2006069164 A JP 2006069164A JP 2006069164 A JP2006069164 A JP 2006069164A JP 2007246606 A JP2007246606 A JP 2007246606A
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polystyrene resin
molecular weight
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JP4837407B2 (en
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Ryosuke Chiumi
良輔 地海
Saburo Fujii
三朗 藤井
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Sekisui Kasei Co Ltd
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Sekisui Plastics Co Ltd
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Abstract

<P>PROBLEM TO BE SOLVED: To provide a sliced article of expanded polystyrene resin free from margin of melt cutting with Nichrome wire in the particle and between the particles, imparting an even and flat cut face, and to provide a suitable material for producing the same. <P>SOLUTION: The invention relates to the sliced article of expanded polystyrene resin obtained by pre-expansion and in-mold expansion of the expandable polystyrene particle and then cutting the expansion molded article by Nichrome wire, wherein the total polystyrene resin particle has 33-50×10<SP>4</SP>of weight average molecular weight, and the expandable polystyrene resin particle has 0.5-5% of molecular weight degradation rate (%) calculated according to the following formula (1), in the formula (X) is a weight average molecular weight of the surface layer of the polystyrene particle, (Y) is a weight average molecular weight of the whole of particle. Formula (1); molecular weight degradation rate (%)=(Y-X)/Y×100. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

本発明は、発泡性ポリスチレン系樹脂粒子、ポリスチレン系樹脂発泡粒子、ポリスチレン系樹脂発泡成形体、ポリスチレン系樹脂発泡体スライス品及びその製造方法に関し、特に、発泡成形体をニクロム線などの電気抵抗加熱線(以下、ニクロム線と記す。)で所望形状にカット(以下、ニクロムカットと記す。)して得られたスライス品のカット面の平滑性、及び融けしろを改善でき、綺麗なカット面を有するポリスチレン系樹脂発泡体スライス品を提供する技術に関する。   TECHNICAL FIELD The present invention relates to expandable polystyrene resin particles, polystyrene resin foam particles, polystyrene resin foam molded products, polystyrene resin foam slices, and a method for producing the same, and in particular, the foam molded products are heated by electric resistance such as nichrome wire. The smoothness and meltability of the cut surface of the sliced product obtained by cutting into a desired shape (hereinafter referred to as nichrome cut) with a wire (hereinafter referred to as nichrome wire) can be improved, and a clean cut surface can be obtained. The present invention relates to a technology for providing a polystyrene resin foam sliced product.

ポリスチレン系樹脂発泡成形体(ブロック)を、スライサー、もしくはニクロム線に通電加熱して使用目的に合った形状にカットし、得られた発泡体スライス品を、例えば建材用のパネル等に使用する用途が増えてきている。この種の用途では、カット面に対する要求品質が高まっている。従来技術では、ニクロムカット面の凹凸が大きいために、見栄えが悪くなり、またアルミ等のパネルを接着して使用する場合に接着強度が不十分であったり、ニクロム線による融けしろが大きいため、歩留まりが悪くなる等の問題があった。
従来、ニクロムカットした時に綺麗なカット面が得られる発泡体を得るために、例えば、特許文献1〜5に開示された技術が提案されている。
The polystyrene resin foam molding (block) is cut into a shape suitable for the intended use by energizing and heating a slicer or nichrome wire, and the resulting foam slice is used for, for example, a panel for building materials Is increasing. In this type of application, the required quality for the cut surface is increasing. In the prior art, since the unevenness of the nichrome cut surface is large, it looks bad, and when bonding and using a panel such as aluminum, the adhesive strength is insufficient, or the melt by the nichrome wire is large, There were problems such as poor yield.
Conventionally, for example, techniques disclosed in Patent Documents 1 to 5 have been proposed in order to obtain a foam that can obtain a clean cut surface when Nichrome is cut.

特許文献1には、ブロック状発泡成形品をスライサー、もしくはニクロム線に通電加熱して使用目的にあった形にカットして使用する場合、綺麗な切断面が得られる発泡体を生じるようなスチレン系重合体粒子を製造することを目的とし、スチレン系重合体粒子を水性媒体中に懸濁させ、この水性懸濁液にスチレン系単量体を添加し60〜100℃の温度条件下で該重合体粒子を該単量体により膨潤、軟化させた後、重合開始剤を添加し、その後発泡剤を加えることを特徴とする発泡性スチレン系重合体粒子の製造方法が開示されている。   Patent Document 1 discloses a styrene that produces a foamed product with a beautiful cut surface when a block-shaped foamed molded product is cut into a shape suitable for the purpose of use by applying heat to a slicer or nichrome wire. In order to produce the polymer particles, the styrene polymer particles are suspended in an aqueous medium, and a styrene monomer is added to the aqueous suspension, and the styrene polymer particles are added at a temperature of 60 to 100 ° C. A method for producing expandable styrenic polymer particles is disclosed in which polymer particles are swollen and softened with the monomer, a polymerization initiator is added, and then a foaming agent is added.

特許文献2には、易揮発性発泡剤を含有する発泡性スチレン系重合体粒子において、上記スチレン系重合体粒子表層部の重量平均分子量が、重合体粒子全体の重量平均分子量より3〜30%高くされていることを特徴とする発泡性スチレン系重合体粒子が開示されている。   In Patent Document 2, in the expandable styrene polymer particles containing a readily volatile foaming agent, the weight average molecular weight of the surface layer portion of the styrene polymer particles is 3 to 30% from the weight average molecular weight of the entire polymer particles. Expandable styrenic polymer particles characterized by being elevated are disclosed.

特許文献3には、樹脂粒子の表面から中心に向かって5等分した表面から1/5までを形成する表面部分を、さらに表面から中心に向かって6等分したときの表面から1/6〜6/6までを形成する部分において、重量平均分子量が表面に向かって低下しないことを特徴とするスチレン系発泡性樹脂粒子が開示され、さらに該文献には、樹脂粒子全体の重量平均分子量(A)に対する、6等分した表面から1/6までを形成する最表面部分aの重量平均分子量(B)の比率(B)/(A)×100(%)が、130以上であることが好ましいことが記載されている。   In Patent Document 3, a surface portion that forms 1/5 from the surface divided into 5 equal parts from the surface of the resin particle toward the center is further divided into 1/6 from the surface when the surface part is further divided into 6 parts from the surface toward the center. A styrene-based expandable resin particle is disclosed in which the weight average molecular weight does not decrease toward the surface in the portion forming ˜6 / 6, and the document further describes the weight average molecular weight ( The ratio (B) / (A) × 100 (%) of the weight average molecular weight (B) of the outermost surface portion a forming from 1 to 6 to the 1/6 surface relative to A) is 130 or more. Preferred is described.

特許文献4には、スチレン系樹脂からなり、粒子最表層部と粒子中心部が低分子量であり、粒子中間部が高分子量である樹脂粒子に易揮発性発泡剤を含浸させてなる発泡性スチレン樹脂粒子及び低分子量スチレン系樹脂粒子及び重合触媒の存在下にスチレン系単量体を重合させて、高分子量スチレン系樹脂からなる粒子中間部表層部及び低分子量スチレン系樹脂粒子からなる最表層を形成し、この重合の途中又はその後に易揮発性発泡剤を含浸する発泡性スチレン系樹脂粒子の製造方法が記載されている。   Patent Document 4 discloses an expandable styrene obtained by impregnating a resin particle having a low molecular weight at the outermost surface layer portion and the particle center portion of the particle, and having a high molecular weight at the middle portion of the particle with an easily volatile foaming agent. Resin particles, low molecular weight styrene resin particles and a styrene monomer in the presence of a polymerization catalyst are polymerized to form a middle layer surface layer portion composed of high molecular weight styrene resin and an outermost layer composed of low molecular weight styrene resin particles. A process for producing expandable styrenic resin particles formed and impregnated with a readily volatile foaming agent during or after the polymerization is described.

特許文献5には、スチレン系樹脂からなり、粒子中心部が低分子量であり、粒子外層部が高分子量である樹脂粒子に易揮発性発泡剤を含浸させてなる発泡性スチレン樹脂粒子及び第1の段階としてスチレン系単量体を重合開始剤の存在下に懸濁重合させ、第2の段階として第1の懸濁重合の途中で、スチレン系単量体を添加して懸濁重合させることを特徴とする発泡性スチレン系樹脂粒子の製造法が開示されている。
特開平9−3235号公報 特開平7−188454号公報 特開2004−137448号公報 特開平8−295756号公報 特開平8−295757号公報
Patent Document 5 discloses a foamable styrene resin particle formed by impregnating a readily volatile foaming agent into a resin particle comprising a styrene-based resin, having a low molecular weight at the center of the particle, and a high molecular weight at the particle outer layer. As a step, suspension polymerization of a styrene monomer in the presence of a polymerization initiator is performed, and as a second step, suspension polymerization is performed by adding a styrene monomer during the first suspension polymerization. A process for producing expandable styrene resin particles is disclosed.
Japanese Patent Laid-Open No. 9-3235 JP-A-7-188454 JP 2004-137448 A JP-A-8-295756 JP-A-8-295757

しかしながら、特許文献1〜5記載の従来技術には、次のような問題がある。
特許文献1記載の従来技術では、ニクロムカット面をピンホールの少ない面にすることはできるが、表層部の分子量が粒子全体の分子量に比べて低下していないため、平滑性については不十分であり、カット面が凹凸になる問題がある。
特許文献2記載の従来技術では、粒子の中心部に比べて表層部の分子量が高いために、ニクロムカット時の融けしろに差が発生し、カット面が凹凸になる問題がある。
特許文献3記載の従来技術は、表層部の分子量が粒子全体の分子量に比べて低下していないため、ニクロムカット時の融けしろに差が発生し、カット面が凹凸になる問題がある。
特許文献4記載の従来技術では、表層部と中心部が低分子量であり、粒子中間部が高分子量であるために、融けしろに差が発生し、カット面が凹凸になる。また、分子量が低いために、歩留まりが悪くなる問題がある。
特許文献5記載の従来技術では、粒子の中心部に比べて表層部の分子量が高いために、ニクロムカット時の融けしろに差が発生し、カット面が凹凸になる問題がある。
これらの原因として、ポリスチレン系樹脂の重量平均分子量の影響及び成形品における発泡粒子の界面の影響(密度の高いスキン層が重なるため、耐熱性が高くなること)等が考えられる。
However, the conventional techniques described in Patent Documents 1 to 5 have the following problems.
In the prior art described in Patent Document 1, the nichrome cut surface can be a surface with few pinholes, but the smoothness is not sufficient because the molecular weight of the surface layer portion is not lower than the molecular weight of the entire particle. There is a problem that the cut surface becomes uneven.
In the prior art described in Patent Document 2, since the molecular weight of the surface layer portion is higher than that of the center portion of the particles, there is a problem that a difference occurs in the melting margin at the time of nichrome cutting and the cut surface becomes uneven.
The conventional technique described in Patent Document 3 has a problem that the molecular weight of the surface layer portion is not lower than the molecular weight of the entire particle, so that a difference occurs in the melting margin at the time of nichrome cutting and the cut surface becomes uneven.
In the prior art described in Patent Document 4, since the surface layer part and the center part have a low molecular weight and the middle part of the particle has a high molecular weight, a difference occurs in the melting margin and the cut surface becomes uneven. Moreover, since the molecular weight is low, there is a problem that the yield is deteriorated.
In the prior art described in Patent Document 5, since the molecular weight of the surface layer portion is higher than that of the center portion of the particle, there is a problem in that a difference occurs in the melting margin at the time of nichrome cutting and the cut surface becomes uneven.
As these causes, the influence of the weight average molecular weight of the polystyrene resin and the influence of the interface of the expanded particles in the molded product (because the skin layers with high density overlap, heat resistance becomes high) and the like are considered.

本発明は、前記事情に鑑みてなされ、ニクロムカット時の融けしろの差が粒子内及び粒子間で無くなり、凹凸がなく平滑なカット面を得ることが可能なポリスチレン系樹脂発泡体スライス品、及びその製造に好適な素材の提供を目的とする。   The present invention has been made in view of the above circumstances, and the difference in meltability at the time of nichrome cutting is eliminated between the particles and between the particles, and a polystyrene-based resin foam slice product capable of obtaining a smooth cut surface without unevenness, and The object is to provide a material suitable for the production.

前記目的を達成するため、本発明は、易揮発性発泡剤を含有する発泡性ポリスチレン系樹脂粒子であって、ポリスチレン系樹脂粒子全体の重量平均分子量が33万〜50万の範囲にあり、かつポリスチレン系樹脂粒子表層部の重量平均分子量を(X)とし、粒子全体の重量平均分子量を(Y)とした時、次式(1)で求められる分子量低下率(%):
分子量低下率(%)=(Y−X)/Y×100 ・・・(1)
が0.5%〜5%の範囲内であることを特徴とする発泡性ポリスチレン系樹脂粒子を提供する。
前記発泡性ポリスチレン系樹脂粒子において、スチレン系単量体、エチルベンゼン、イソプロピルベンゼン、ノルマルプロピルベンゼン、キシレン、トルエンからなる芳香族有機化合物の含有量の総和が2000ppm未満であることが好ましい。
また、前記発泡性ポリスチレン系樹脂粒子において、難燃剤を含有していることが好ましい。
さらに、前記発泡性ポリスチレン系樹脂粒子において、架橋剤を含有していることが好ましい。
In order to achieve the above object, the present invention is an expandable polystyrene resin particle containing a readily volatile foaming agent, wherein the polystyrene resin particle as a whole has a weight average molecular weight in the range of 330,000 to 500,000, and When the weight average molecular weight of the surface layer of the polystyrene-based resin particle is (X) and the weight average molecular weight of the entire particle is (Y), the molecular weight reduction rate (%) obtained by the following formula (1):
Molecular weight reduction rate (%) = (Y−X) / Y × 100 (1)
Is within the range of 0.5% to 5%, and provides expandable polystyrene resin particles.
In the expandable polystyrene resin particles, the total content of aromatic organic compounds composed of styrene monomers, ethylbenzene, isopropylbenzene, normal propylbenzene, xylene, and toluene is preferably less than 2000 ppm.
The expandable polystyrene resin particles preferably contain a flame retardant.
Furthermore, it is preferable that the expandable polystyrene resin particles contain a crosslinking agent.

また本発明は、前記本発明に係る発泡性ポリスチレン系樹脂粒子を加熱し予備発泡させて得られたポリスチレン系樹脂発泡粒子であって、粒子全体の重量平均分子量が33万〜50万の範囲にあり、かつ発泡粒子表層部の重量平均分子量を(X)とし、発泡粒子全体の重量平均分子量を(Y)とした時、次式(1)で求められる分子量低下率(%):
分子量低下率(%)=(Y−X)/Y×100 ・・・(1)
が0.5%〜5%の範囲内であることを特徴とするポリスチレン系樹脂発泡粒子を提供する。
Further, the present invention is a polystyrene resin expanded particle obtained by heating and pre-expanding the expandable polystyrene resin particle according to the present invention, wherein the weight average molecular weight of the entire particle is in the range of 330,000 to 500,000. When the weight average molecular weight of the foamed particle surface layer part is (X) and the weight average molecular weight of the whole foamed particle is (Y), the molecular weight reduction rate (%) calculated by the following formula (1):
Molecular weight reduction rate (%) = (Y−X) / Y × 100 (1)
Is within the range of 0.5% to 5%.

また本発明は、前述した本発明に係るポリスチレン系樹脂発泡粒子を型内発泡成形して得られたポリスチレン系樹脂発泡成形体を製造する。   Moreover, this invention manufactures the polystyrene-type resin foam molding obtained by carrying out in-mold foam molding of the polystyrene-type resin expanded particle which concerns on this invention mentioned above.

また本発明は、前述した本発明に係るポリスチレン系樹脂発泡成形体を電気抵抗加熱線で所望形状にカットして得られたポリスチレン系樹脂発泡体スライス品を提供する。
前記ポリスチレン系樹脂発泡体スライス品において、カット面における亀甲高さが50μm以下であることが好ましい。
前記ポリスチレン系樹脂発泡体スライス品において、カット面における融けしろの量が3%未満であることが好ましい。
The present invention also provides a polystyrene resin foam slice product obtained by cutting the polystyrene resin foam molded article according to the present invention into a desired shape with an electric resistance heating wire.
In the polystyrene resin foam sliced product, the turtle shell height on the cut surface is preferably 50 μm or less.
In the polystyrene resin foam sliced product, it is preferable that the amount of melt on the cut surface is less than 3%.

また本発明は、水性媒体と、ポリスチレン系樹脂核粒子と、スチレン系単量体と、重合開始剤とを反応容器内に入れて加熱反応させ、ポリスチレン系樹脂核粒子の表面に新たにポリスチレン系樹脂層を形成し、易揮発性発泡剤を含浸させて発泡性ポリスチレン系樹脂粒子を得る製造方法であって、粒子全体の重量平均分子量が33万〜50万の範囲にあり、かつ発泡粒子表層部の重量平均分子量を(X)とし、発泡粒子全体の重量平均分子量を(Y)とした時、次式(1)で求められる分子量低下率(%):
分子量低下率(%)=(Y−X)/Y×100 ・・・(1)
が0.5%〜5%の範囲内である発泡性ポリスチレン系樹脂粒子を得ることを特徴とする発泡性ポリスチレン系樹脂粒子の製造方法を提供する。
The present invention also includes an aqueous medium, a polystyrene resin core particle, a styrene monomer, and a polymerization initiator placed in a reaction vessel and subjected to a heat reaction, and a new polystyrene base is formed on the surface of the polystyrene resin core particle. A production method for forming a resin layer and impregnating a readily volatile foaming agent to obtain expandable polystyrene resin particles, wherein the weight average molecular weight of the entire particles is in the range of 330,000 to 500,000, and the surface layer of the expanded particles When the weight average molecular weight of the part is (X) and the weight average molecular weight of the whole expanded particle is (Y), the molecular weight reduction rate (%) obtained by the following formula (1):
Molecular weight reduction rate (%) = (Y−X) / Y × 100 (1)
The present invention provides a method for producing expandable polystyrene resin particles, characterized in that expandable polystyrene resin particles having a content of 0.5% to 5% are obtained.

本発明の発泡性ポリスチレン系樹脂粒子は、易揮発性発泡剤を含有しており、粒子全体の重量平均分子量を33万〜50万の範囲としたことにより、耐熱性が上がり、該樹脂粒子を用いて製造したポリスチレン系樹脂発泡成形体は、ニクロムカットによる融けしろを小さくすることができ、製品の歩留まりを改善することができる。また、粒子表層部分の重量平均分子量を粒子全体の重量平均分子量に対して0.5〜5%低下させた構成としたことによって、該樹脂粒子を用いて製造したポリスチレン系樹脂発泡成形体は、ニクロムカット時の融けしろの差が粒子内及び粒子間で無くなり、凹凸がなく平滑なカット面を得ることができる。
本発明のポリスチレン系樹脂発泡粒子は、前記発泡性ポリスチレン系樹脂粒子を加熱し予備発泡させたものなので、該発泡粒子を用いて製造したポリスチレン系樹脂発泡成形体は、ニクロムカットによる融けしろを小さくすることができ、製品の歩留まりを改善することができ、またニクロムカット時の融けしろの差が粒子内及び粒子間で無くなり、凹凸がなく平滑なカット面を得ることができる。
本発明のポリスチレン系樹脂発泡成形体は、前記ポリスチレン系樹脂発泡粒子を型内発泡成形したものなので、ニクロムカットによる融けしろを小さくすることができ、製品の歩留まりを改善することができ、またニクロムカット時の融けしろの差が粒子内及び粒子間で無くなり、凹凸がなく平滑なカット面を得ることができる。
本発明のポリスチレン系樹脂発泡体スライス品は、前記ポリスチレン系樹脂発泡成形体を所望の形状にニクロムカットしたものなので、ニクロムカットによる融けしろを小さくすることができ、製品の歩留まりを改善することができ、またニクロムカット時の融けしろの差が粒子内及び粒子間で無くなり、凹凸がなく平滑なカット面を得ることができる。
The expandable polystyrene resin particles of the present invention contain a readily volatile foaming agent, and by setting the weight average molecular weight of the entire particles in the range of 330,000 to 500,000, the heat resistance is increased, The polystyrene-based resin foam-molded article produced by using it can reduce the melting margin due to the nichrome cut, and can improve the yield of the product. Moreover, the polystyrene-based resin foam molded article produced using the resin particles by reducing the weight average molecular weight of the particle surface layer portion by 0.5 to 5% with respect to the weight average molecular weight of the entire particles, The difference in melting margin at the time of nichrome cutting is eliminated within and between particles, and a smooth cut surface without irregularities can be obtained.
Since the polystyrene-based resin expanded particles of the present invention are pre-expanded by heating the expandable polystyrene-based resin particles, the polystyrene-based resin foam molded body produced using the expanded particles has a small melting margin due to nichrome cut. Thus, the yield of the product can be improved, and the difference in meltability at the time of nichrome cutting is eliminated between the particles and between the particles, so that a smooth cut surface without irregularities can be obtained.
Since the polystyrene resin foam molded article of the present invention is obtained by in-mold foam molding of the polystyrene resin foam particles, it is possible to reduce the melting margin due to nichrome cut, improve the yield of the product, and nichrome. The difference in meltability at the time of cutting is eliminated between the particles and between the particles, and a smooth cut surface having no irregularities can be obtained.
Since the polystyrene-based resin foam slice of the present invention is obtained by nichrome cutting the polystyrene-based resin foam molding into a desired shape, the melting margin due to nichrome cutting can be reduced, and the yield of products can be improved. In addition, the difference in meltability at the time of cutting nichrome is eliminated between the particles and between the particles, and a smooth cut surface with no irregularities can be obtained.

本発明の発泡性ポリスチレン系樹脂粒子の製造方法は、水性媒体と、ポリスチレン系樹脂核粒子と、スチレン系単量体と、重合開始剤とを反応容器内に入れて加熱反応させ、ポリスチレン系樹脂核粒子の表面に新たにポリスチレン系樹脂層を形成し、易揮発性発泡剤を含浸させて発泡性ポリスチレン系樹脂粒子を製造する際に、粒子全体の重量平均分子量を33万〜50万の範囲とすること、及び粒子表層部分の重量平均分子量を粒子全体の重量平均分子量に対して0.5〜5%低下するように製造することによって、ニクロムカットによる融けしろを小さくすることができ、製品の歩留まりを改善することができ、ニクロムカット時の融けしろの差が粒子内及び粒子間で無くなり、凹凸がなく平滑なカット面を得ることができる、加工特性に優れたポリスチレン系樹脂発泡成形体の製造に適した発泡性ポリスチレン系樹脂粒子を提供できる。   The method for producing expandable polystyrene resin particles according to the present invention includes an aqueous medium, polystyrene resin core particles, a styrene monomer, and a polymerization initiator that are heated and reacted in a reaction vessel. When a polystyrene-based resin layer is newly formed on the surface of the core particle and impregnated with a readily volatile foaming agent to produce expandable polystyrene-based resin particles, the weight average molecular weight of the entire particle is in the range of 330,000 to 500,000. And by making the weight average molecular weight of the particle surface layer portion lower by 0.5 to 5% with respect to the weight average molecular weight of the entire particle, the melting margin due to nichrome cut can be reduced, and the product Yield can be improved, the difference in meltability when cutting nichrome is eliminated between particles and between particles, and a smooth cut surface can be obtained without irregularities. It can provide expandable polystyrene resin particles which are suitable for the manufacture of superior polystyrene type resin foamed molded article.

本発明の発泡性ポリスチレン系樹脂粒子は、易揮発性発泡剤を含有するポリスチレン系樹脂からなる発泡性ポリスチレン系樹脂粒子であって、粒子全体の重量平均分子量が33万〜50万の範囲にあり、かつポリスチレン系樹脂粒子表層部の重量平均分子量を(X)とし、粒子全体の重量平均分子量を(Y)とした時、次式(1)で求められる分子量低下率(%):
分子量低下率(%)=(Y−X)/Y×100 ・・・(1)
が0.5%〜5%の範囲内であることを特徴としている。
The expandable polystyrene resin particles of the present invention are expandable polystyrene resin particles made of a polystyrene resin containing a readily volatile foaming agent, and the weight average molecular weight of the entire particles is in the range of 330,000 to 500,000. And when the weight average molecular weight of the polystyrene resin particle surface layer part is (X) and the weight average molecular weight of the whole particle is (Y), the molecular weight reduction rate (%) calculated by the following formula (1):
Molecular weight reduction rate (%) = (Y−X) / Y × 100 (1)
Is in the range of 0.5% to 5%.

本発明の発泡性ポリスチレン系樹脂粒子を構成するポリスチレン系樹脂としては、例えば、スチレン、α−メチルスチレン、p−メチルスチレン、t−ブチルスチレン等のスチレン系単量体を重合させて得られる樹脂が挙げられる。更に、ポリスチレン系樹脂は、スチレン系単量体と、該スチレン系単量体と共重合可能な他の単量体との共重合体であってもよい。他の単量体としては、ジビニルベンゼンのような多官能性単量体や、(メタ)アクリル酸ブチルのような構造中にベンゼン環を含まない(メタ)アクリル酸アルキルエステル等が例示される。これら他の単量体は、実質的にポリスチレン系樹脂に対して5質量%を超えない範囲で使用してもよい。なお、本明細書では、スチレン及びスチレンと共重合可能な単量体もスチレン系単量体と称している。   Examples of the polystyrene resin constituting the expandable polystyrene resin particles of the present invention include a resin obtained by polymerizing styrene monomers such as styrene, α-methylstyrene, p-methylstyrene, and t-butylstyrene. Is mentioned. Furthermore, the polystyrene resin may be a copolymer of a styrene monomer and another monomer copolymerizable with the styrene monomer. Examples of other monomers include polyfunctional monomers such as divinylbenzene, and (meth) acrylic acid alkyl esters that do not contain a benzene ring in the structure such as butyl (meth) acrylate. . You may use these other monomers in the range which does not exceed 5 mass% substantially with respect to a polystyrene-type resin. In the present specification, styrene and a monomer copolymerizable with styrene are also referred to as a styrene monomer.

本発明の発泡性ポリスチレン系樹脂粒子は、易揮発性発泡剤を含有しており、粒子全体の重量平均分子量が33万〜50万の範囲内であるので、耐熱性が高くなり、該樹脂粒子を用いて製造したポリスチレン系樹脂発泡成形体は、ニクロムカットによる融けしろを小さくすることができ、製品の歩留まりを改善することができる。粒子全体の重量平均分子量が33万未満であると、製造したポリスチレン系樹脂発泡成形体の耐熱性が低くなり、ニクロムカットによる融けしろが大きくなり、カット面の亀甲高さが大きくなって、平滑な面が得られなくなる。また、粒子全体の重量平均分子量が50万を超えると、発泡性が低下し、成形時の発泡粒子同士が融着しにくくなり、発泡成形体の強度が低下する。   The expandable polystyrene resin particles of the present invention contain a readily volatile foaming agent, and the weight average molecular weight of the entire particles is within the range of 330,000 to 500,000. The polystyrene-based resin foam-molded article produced using can reduce the melting margin due to nichrome cut, and can improve the yield of products. If the weight average molecular weight of the whole particle is less than 330,000, the heat resistance of the produced polystyrene resin foam molding is lowered, the melting margin due to nichrome cut is increased, the tortoiseshell height of the cut surface is increased, and smoothness is achieved. A difficult aspect cannot be obtained. Moreover, when the weight average molecular weight of the whole particle | grain exceeds 500,000, foamability will fall, it will become difficult to fuse the foaming particles at the time of shaping | molding, and the intensity | strength of a foaming molding will fall.

本発明の発泡性ポリスチレン系樹脂粒子は、前記式(1)で求められる分子量低下率が0.5%〜5%の範囲内であること、換言すれば、粒子表層部分の重量平均分子量が粒子全体の重量平均分子量に対して0.5〜5%低下した構成としたことによって、該樹脂粒子を用いて製造したポリスチレン系樹脂発泡成形体は、ニクロムカット時の融けしろの差が粒子内及び粒子間で無くなり、凹凸がなく平滑なカット面を得ることができる。前記分子量低下率が0.5%よりも小さいと、得られるポリスチレン系樹脂発泡成形体をニクロムカットした際に、カット面の亀甲高さが大きくなって、平滑な面が得られなくなる。また前記分子量低下率が5%より大きいと、粒子表面の耐熱性が低くなり、やはり得られる発泡成形体のカット面の亀甲高さが大きくなって、平滑な面が得られなくなる。   The expandable polystyrene resin particles of the present invention have a molecular weight reduction rate calculated by the above formula (1) in the range of 0.5% to 5%, in other words, the weight average molecular weight of the particle surface layer portion is a particle. The polystyrene resin foam molded product produced using the resin particles has a difference in meltability during the nichrome cut in the particles and by reducing the 0.5 to 5% of the total weight average molecular weight. A smooth cut surface can be obtained without any irregularity between the particles. When the molecular weight reduction rate is less than 0.5%, when the resulting polystyrene-based resin foam molded article is Nichrome cut, the tortoiseshell height of the cut surface becomes large, and a smooth surface cannot be obtained. On the other hand, if the molecular weight reduction rate is larger than 5%, the heat resistance of the particle surface is lowered, the turtle shell height of the cut surface of the foamed molded product is also increased, and a smooth surface cannot be obtained.

本発明の発泡性ポリスチレン系樹脂粒子の形状や粒径は、特に限定されないが、この樹脂粒子を用いてポリスチレン系樹脂発泡成形体を製造する際に表面状態がよく、機械強度にも優れた成形体が得られることから、球状又は球状に近い形状の粒子が好ましく、また平均粒径が0.3mm〜2mm程度であることが好ましい。   The shape and particle size of the expandable polystyrene resin particles of the present invention are not particularly limited, but when producing a polystyrene resin foam molded article using these resin particles, the surface state is good and the molding is excellent in mechanical strength. Since a body is obtained, particles having a spherical shape or a shape close to a spherical shape are preferable, and the average particle size is preferably about 0.3 mm to 2 mm.

本発明の発泡性ポリスチレン系樹脂粒子には、必要に応じて各種の添加剤を添加してもよい。添加剤としては、難燃剤、発泡核剤、充填剤、可塑剤、着色剤、紫外線吸収剤、酸化防止剤等が挙げられる。
難燃剤としては、ヘキサブロモシクロドデカン、テトラブロモブタン、ヘキサブロモシクロヘキサン等の臭素化脂肪族炭化水素系化合物、テトラブロモビスフェノールA、テトラブロモビスフェノールF、2,4,6−トリブロモフェノール等の臭素化フェノール類、テトラブロモビスフェノールA−ビス(2,3−ジブロモプロピルエーテル)、テトラブロモビスフェノールA−ジグリシジルエーテル等の臭素化フェノール誘導体等が挙げられる。
発泡核剤としては、タルク、珪酸カルシウム、エチレンビスステアリン酸アミド、メタクリル酸エステル系共重合体等が挙げられる。
充填剤としては、合成あるいは天然に産出される二酸化ケイ素等が挙げられる。
可塑剤としては、ジイソブチルアジペート、流動パラフィン、グリセリンジアセトモノラウレート、やし油等が挙げられる。
着色剤としては、カーボンブラック、グラファイト、酸化鉄等が挙げられる。
Various additives may be added to the expandable polystyrene resin particles of the present invention as necessary. Examples of the additive include a flame retardant, a foam nucleating agent, a filler, a plasticizer, a colorant, an ultraviolet absorber, and an antioxidant.
Flame retardants include brominated aliphatic hydrocarbon compounds such as hexabromocyclododecane, tetrabromobutane, hexabromocyclohexane, bromine such as tetrabromobisphenol A, tetrabromobisphenol F, 2,4,6-tribromophenol And brominated phenol derivatives such as tetrabromobisphenol A-bis (2,3-dibromopropyl ether) and tetrabromobisphenol A-diglycidyl ether.
Examples of the foam nucleating agent include talc, calcium silicate, ethylene bis stearamide, and a methacrylic ester copolymer.
Examples of the filler include synthetic or naturally produced silicon dioxide.
Examples of the plasticizer include diisobutyl adipate, liquid paraffin, glycerin diacetomonolaurate, and palm oil.
Examples of the colorant include carbon black, graphite, and iron oxide.

次に、本発明の発泡性ポリスチレン系樹脂粒子の製造方法の一例を説明する。
本例では、次の(A)及び(B)の2つの重合工程を経て、球状の型内発泡成形用ポリスチレン系樹脂粒子を得て、その樹脂粒子に易揮発性発泡剤を含浸させて発泡性ポリスチレン系樹脂粒子を製造する。
(A)反応容器内に分散剤を含む水性媒体を入れ、この中に、スチレン系単量体と、重合開始剤を入れ、必要に応じて前述した添加剤や架橋剤を添加し、加熱、撹拌してスチレン系単量体を重合させ、平均粒径が0.5mm〜0.7mm程度のポリスチレン系樹脂種粒子を形成する懸濁重合工程、
(B)次いで、前記(A)工程で得られたポリスチレン系樹脂種粒子と、重合開始剤と、必要に応じて前述した添加剤や架橋剤とを水性媒体に入れ、加熱、撹拌しながら、スチレン系単量体を滴下し、ポリスチレン系樹脂種粒子表面にスチレン系単量体の重合により生じるポリスチレン系樹脂層を形成し、平均粒径が0.85mm〜1.2mm程度の型内発泡成形用ポリスチレン系樹脂粒子を製造するシード重合工程。
Next, an example of the manufacturing method of the expandable polystyrene resin particle of this invention is demonstrated.
In this example, through the following two polymerization steps (A) and (B), polystyrene resin particles for spherical in-mold foam molding are obtained, and foamed by impregnating the resin particles with a readily volatile foaming agent. -Based polystyrene resin particles are produced.
(A) An aqueous medium containing a dispersant is placed in a reaction vessel, and a styrene monomer and a polymerization initiator are placed therein. If necessary, the additives and cross-linking agents described above are added and heated. Suspension polymerization step of polymerizing the styrene monomer by stirring to form polystyrene resin seed particles having an average particle size of about 0.5 mm to 0.7 mm,
(B) Next, the polystyrene resin seed particles obtained in the step (A), the polymerization initiator, and the additives and cross-linking agents described above as necessary are placed in an aqueous medium, while heating and stirring, Styrene monomer is dropped to form a polystyrene resin layer formed by polymerization of styrene monomer on the surface of polystyrene resin seed particles, and in-mold foam molding with an average particle size of about 0.85 mm to 1.2 mm Seed polymerization process for producing polystyrene resin particles.

なお、本発明の発泡性ポリスチレン系樹脂粒子の製造方法は、前記例示に限定されず、例えば、種粒子を製造するのに(A)懸濁重合工程に代えて、適当な重量平均分子量を持ったポリスチレン系樹脂を押出機に投入し、ダイの細孔から押し出すと同時に水中に導いてカットし、略球状のペレットを得る方法(水中カット法)などによって製造された種粒子を用いることもできる。   In addition, the manufacturing method of the expandable polystyrene resin particle of this invention is not limited to the said illustration, For example, it replaces with (A) suspension polymerization process in order to manufacture a seed particle, and has a suitable weight average molecular weight. It is also possible to use seed particles produced by, for example, introducing a polystyrene resin into an extruder and extruding it through the pores of the die and simultaneously guiding it into water to cut it to obtain a substantially spherical pellet (underwater cutting method). .

前記(A)工程で用いられる分散剤としては、例えば、部分ケン化ポリビニルアルコール、ポリアクリル酸塩、ポリビニルピロリドン、カルボキシメチルセルロース、メチルセルロース等の有機系分散剤、ピロリン酸マグネシウム、ピロリン酸カルシウム、リン酸カルシウム、炭酸カルシウム、リン酸マグネシウム、炭酸マグネシウム、酸化マグネシウム等の無機系分散剤等が挙げられる。この内、無機系分散剤が好ましい。無機系分散剤を用いる場合には、界面活性剤を併用することが好ましい。このような界面活性剤としては、例えば、ドデシルベンゼンスルホン酸ソーダ、α−オレフィンスルホン酸ソーダ等が挙げられる。   Examples of the dispersant used in the step (A) include organic dispersants such as partially saponified polyvinyl alcohol, polyacrylate, polyvinyl pyrrolidone, carboxymethyl cellulose, and methyl cellulose, magnesium pyrophosphate, calcium pyrophosphate, calcium phosphate, and carbonic acid. Examples include inorganic dispersants such as calcium, magnesium phosphate, magnesium carbonate, and magnesium oxide. Of these, inorganic dispersants are preferred. When using an inorganic dispersant, it is preferable to use a surfactant in combination. Examples of such surfactants include dodecylbenzene sulfonic acid soda and α-olefin sulfonic acid soda.

また、重合開始剤としては、スチレン系単量体の重合に汎用されている従来周知の重合開始剤を使用できる。例えば、ベンゾイルパーオキサイド、ラウロイルパーオキサイド、t−アミルパーオキシオクトエート、t−ブチルパーオキシベンゾエート、t−アミルパーオキシベンゾエート、t−ブチルパーオキシビバレート、t−ブチルパーオキシイソプロピルカーボネート、t−ブチルパーオキシアセテート、t−ブチルパーオキシ−3,3,5−トリメチルシクロヘキサノエート、ジ−t−ブチルパーオキシヘキサハイドロテレフタレート、2,2−ジ−t−ブチルパーオキシブタン、ジクミルパーオキサイド等の有機過酸化物、アゾビスイソブチロニトリル、アゾビスジメチルバレロニトリル等のアゾ化合物が挙げられる。なお、重合開始剤は、単独で用いられても併用されてもよい。   Moreover, as a polymerization initiator, a conventionally well-known polymerization initiator widely used for polymerization of styrene monomers can be used. For example, benzoyl peroxide, lauroyl peroxide, t-amyl peroxy octoate, t-butyl peroxybenzoate, t-amyl peroxybenzoate, t-butyl peroxybivalate, t-butyl peroxyisopropyl carbonate, t- Butyl peroxyacetate, t-butylperoxy-3,3,5-trimethylcyclohexanoate, di-t-butylperoxyhexahydroterephthalate, 2,2-di-t-butylperoxybutane, dicumyl peroxide And an azo compound such as azobisisobutyronitrile and azobisdimethylvaleronitrile. In addition, a polymerization initiator may be used independently or may be used together.

また架橋剤を添加する場合、その添加方法としては、例えば、溶剤、可塑剤またはスチレン系単量体に架橋剤を溶解させた上で添加する方法、架橋剤を水に分散させた上で添加する方法等が挙げられる。この内、スチレン系単量体に架橋剤を溶解させた上で添加する方法が好ましい。架橋剤としては、例えばジビニルベンゼン、アルキレングリコールジメタクリレート等が挙げられる。   Moreover, when adding a crosslinking agent, the addition method is, for example, a method in which the crosslinking agent is dissolved in a solvent, a plasticizer or a styrene monomer, and a method in which the crosslinking agent is dispersed in water. And the like. Among these, a method of adding a crosslinking agent after dissolving it in a styrene monomer is preferable. Examples of the crosslinking agent include divinylbenzene and alkylene glycol dimethacrylate.

前記(A)懸濁重合工程及び(B)シード重合工程で用いられる水性媒体としては、水、水と水溶性溶媒(例えば、アルコール)との混合媒体が挙げられる。   Examples of the aqueous medium used in the (A) suspension polymerization step and (B) seed polymerization step include water and a mixed medium of water and a water-soluble solvent (for example, alcohol).

本発明の発泡性ポリスチレン系樹脂粒子は、粒子全体の重量平均分子量を33万〜50万の範囲としたことにより、耐熱性が上がり、該樹脂粒子を用いて製造したポリスチレン系樹脂発泡成形体は、ニクロムカットによる融けしろを小さくすることができ、製品の歩留まりを改善することができる。また、粒子表層部分の重量平均分子量を粒子全体の重量平均分子量に対して0.5〜5%低下させた構成としたことによって、該樹脂粒子を用いて製造したポリスチレン系樹脂発泡成形体は、ニクロムカット時の融けしろの差が粒子内及び粒子間で無くなり、凹凸がなく平滑なカット面を得ることができる。   The expandable polystyrene resin particles of the present invention have an increased heat resistance when the weight average molecular weight of the entire particles is in the range of 330,000 to 500,000, and the polystyrene resin foam molded article produced using the resin particles is Further, it is possible to reduce the melting margin due to the nichrome cut and to improve the product yield. Moreover, the polystyrene-based resin foam molded article produced using the resin particles by reducing the weight average molecular weight of the particle surface layer portion by 0.5 to 5% with respect to the weight average molecular weight of the entire particles, The difference in melting margin at the time of nichrome cutting is eliminated within and between particles, and a smooth cut surface without irregularities can be obtained.

本発明の発泡性ポリスチレン系樹脂粒子に含浸させる易揮発性発泡剤としては、沸点が重合体の軟化温度以下である易揮発性を有する、例えばプロパン、n−ブタン、i−ブタン、n−ペンタン、i−ペンタン、シクロペンタン、炭酸ガス、窒素が挙げられ、これらの発泡剤は、単独もしくは2種以上を併用して用いることができる。易揮発性発泡剤の使用量は、型内発泡成形用ポリスチレン系樹脂粒子100質量部に対して5〜25質量部の範囲とすることが好ましい。   As the readily volatile foaming agent impregnated into the expandable polystyrene resin particles of the present invention, the boiling point is not more than the softening temperature of the polymer, for example, propane, n-butane, i-butane, n-pentane. , I-pentane, cyclopentane, carbon dioxide gas, and nitrogen. These blowing agents can be used alone or in combination of two or more. The amount of the readily volatile foaming agent is preferably in the range of 5 to 25 parts by mass with respect to 100 parts by mass of the polystyrene resin particles for in-mold foam molding.

更に、この発泡性ポリスチレン系樹脂粒子には、発泡助剤を発泡剤と共に用いてもよい。このような発泡助剤としては、例えば、ジイソブチルアジペート、ジアセチル化モノラウレート、やし油等の可塑剤(高沸点溶剤)が挙げられる。この発泡助剤の添加量としては、改質樹脂粒子100質量部に対して0.1〜2.5質量部が好ましい。   Furthermore, you may use a foaming adjuvant with a foaming agent for this expandable polystyrene-type resin particle. Examples of such foaming aids include plasticizers (high-boiling solvents) such as diisobutyl adipate, diacetylated monolaurate, and palm oil. The addition amount of the foaming aid is preferably 0.1 to 2.5 parts by mass with respect to 100 parts by mass of the modified resin particles.

また、発泡性ポリスチレン系樹脂粒子には、結合防止剤、融着促進剤、帯電防止剤、展着剤等の表面処理剤を添加してもよい。
結合防止剤は、改質樹脂粒子を予備発泡させる際の予備発泡粒子同士の合着を防止する役割を果たす。ここで、合着とは、予備発泡粒子の複数個が合一して一体化することをいう。具体例としては、タルク、炭酸カルシウム、ステアリン酸亜鉛、水酸化アルミニウム、エチレンビスステアリン酸アミド、第三リン酸カルシウム、ジメチルポリシロキサン等が挙げられる。
融着促進剤は、予備発泡粒子を二次発泡成形する際の予備発泡粒子同士の融着を促進させる役割を果たす。具体例としては、ステアリン酸、ステアリン酸トリグリセリド、ヒドロキシステアリン酸トリグリセリド、ステアリン酸ソルビタンエステル等が挙げられる。
帯電防止剤としては、ポリオキシエチレンアルキルフェノールエーテル、ステアリン酸モノグリセリド等が挙げられる。展着剤としては、ポリブテン、ポリエチレングリコール
、シリコンオイル等が挙げられる。なお、前記表面処理剤の総添加量は、型内発泡成形用ポリスチレン系樹脂粒子100質量部に対して0.01〜2.0質量部の範囲が好ましい。
In addition, a surface treatment agent such as a binding inhibitor, a fusion accelerator, an antistatic agent, or a spreading agent may be added to the expandable polystyrene resin particles.
The anti-bonding agent plays a role of preventing coalescence of the pre-expanded particles when the modified resin particles are pre-expanded. Here, coalescence means that a plurality of pre-expanded particles are united and integrated. Specific examples include talc, calcium carbonate, zinc stearate, aluminum hydroxide, ethylene bis stearamide, tricalcium phosphate, dimethylpolysiloxane and the like.
The fusion accelerator plays a role of promoting fusion between the pre-foamed particles when the pre-foamed particles are subjected to secondary foam molding. Specific examples include stearic acid, stearic acid triglyceride, hydroxystearic acid triglyceride, sorbitan stearate, and the like.
Examples of the antistatic agent include polyoxyethylene alkylphenol ether and stearic acid monoglyceride. Examples of the spreading agent include polybutene, polyethylene glycol, and silicone oil. The total addition amount of the surface treatment agent is preferably in the range of 0.01 to 2.0 parts by mass with respect to 100 parts by mass of the polystyrene resin particles for in-mold foam molding.

本発明の発泡性ポリスチレン系樹脂粒子には、ポリスチレン系樹脂と易揮発性発泡剤以外に、前述した各種の添加剤を必要に応じて添加することができるが、本発明の発泡性ポリスチレン系樹脂粒子は、スチレン系単量体、エチルベンゼン、イソプロピルベンゼン、ノルマルプロピルベンゼン、キシレン、トルエンからなる芳香族有機化合物の含有量の総和が2000ppm未満であることが好ましい。トルエンからなる芳香族有機化合物の含有量の総和が2000ppm未満とすることで、昨今のシックハウス等の環境問題に対応できるポリスチレン系樹脂発泡成形体を提供できる。より好ましくは1000ppm未満であり、最も好ましくは600ppm未満である。   In addition to the polystyrene resin and the readily volatile foaming agent, the above-mentioned various additives can be added to the expandable polystyrene resin particles of the present invention as necessary, but the expandable polystyrene resin of the present invention. The particles preferably have a total content of aromatic organic compounds composed of styrene monomers, ethylbenzene, isopropylbenzene, normal propylbenzene, xylene, and toluene of less than 2000 ppm. By setting the total content of aromatic organic compounds composed of toluene to less than 2000 ppm, it is possible to provide a polystyrene-based resin foam molded article that can cope with environmental problems such as recent sick houses. More preferably it is less than 1000 ppm, and most preferably less than 600 ppm.

型内発泡成形用ポリスチレン系樹脂粒子に易揮発性発泡剤を含浸させる方法は、発泡剤の種類に応じて適宜変更可能である。例えば、型内発泡成形用ポリスチレン系樹脂粒子が分散している水性媒体中に発泡剤を圧入して、該樹脂粒子中に発泡剤を含浸させる方法、型内発泡成形用ポリスチレン系樹脂粒子を回転混合機に供給し、この回転混合機内に易揮発性発泡剤を圧入して該樹脂粒子に易揮発性発泡剤を含浸させる方法などが挙げられる。なお、型内発泡成形用ポリスチレン系樹脂粒子に易揮発性発泡剤を含浸させる温度は、通常、50〜140℃とすることが好ましい。   The method of impregnating the polystyrene-based resin particles for in-mold foam molding with the easily volatile foaming agent can be appropriately changed according to the type of the foaming agent. For example, a method of injecting a foaming agent into an aqueous medium in which polystyrene resin particles for in-mold foam molding are dispersed, and impregnating the foaming agent into the resin particles, rotating polystyrene resin particles for in-mold foam molding Examples thereof include a method of supplying to a mixer and press-fitting a readily volatile foaming agent into the rotary mixer and impregnating the resin particles with the easily volatile foaming agent. The temperature at which the polystyrene resin particles for in-mold foam molding are impregnated with the easily volatile foaming agent is usually preferably 50 to 140 ° C.

本発明は、前述した発泡性ポリスチレン系樹脂粒子を加熱して予備発泡させて得られたポリスチレン系樹脂発泡粒子(以下、予備発泡粒子と記す。)とその製造方法を提供する。この予備発泡の加熱条件や予備発泡に用いる装置は、従来のポリスチレン系樹脂予備発泡粒子の製造の場合と同等とすることができる。例えば、予備発泡装置内で、水蒸気圧0.01〜0.05MPa程度の雰囲気下で発泡性ポリスチレン系樹脂粒子を加熱することによって得ることができる。加熱温度は一般に70℃〜110℃程度である。   The present invention provides polystyrene resin expanded particles (hereinafter referred to as pre-expanded particles) obtained by heating and pre-expanding the expandable polystyrene resin particles described above, and a method for producing the same. The pre-foaming heating conditions and the apparatus used for the pre-foaming can be the same as those for the production of conventional polystyrene resin pre-foamed particles. For example, it can be obtained by heating expandable polystyrene resin particles in an atmosphere of a water vapor pressure of about 0.01 to 0.05 MPa in a pre-foaming apparatus. The heating temperature is generally about 70 ° C to 110 ° C.

この予備発泡粒子は、0.0125〜0.05g/cmの嵩密度を有する。好ましい嵩密度は、0.015〜0.025g/cmである。嵩密度が0.0125g/cmより小さいと、発泡粒子の独立気泡率が低下して、予備発泡粒子を発泡させて得られる発泡成形体の強度が低下するため好ましくない。一方、嵩密度が0.05g/cmより大きいと、予備発泡粒子を発泡させて得られる発泡成形体の質量が増加するので好ましくない。 The pre-expanded particles have a bulk density of 0.0125 to 0.05 g / cm 3 . A preferred bulk density is 0.015 to 0.025 g / cm 3 . When the bulk density is less than 0.0125 g / cm 3 , the closed cell ratio of the expanded particles is decreased, and the strength of the expanded molded product obtained by foaming the pre-expanded particles is not preferable. On the other hand, if the bulk density is larger than 0.05 g / cm 3 , the mass of the foamed molded product obtained by foaming the pre-expanded particles is not preferable.

予備発泡粒子の形態は、その後の型内発泡成形に影響を与えないものであれば、特に限定されない。例えば、真球状、楕円球状(卵状)、円柱状、角柱状等が挙げられる。この内、成形型のキャビティ内への充填が容易である真球状、楕円球状が好ましい。   The form of the pre-expanded particles is not particularly limited as long as it does not affect the subsequent in-mold foam molding. For example, a true spherical shape, an elliptical spherical shape (egg shape), a cylindrical shape, a prismatic shape, and the like can be given. Of these, a true spherical shape and an elliptical spherical shape, which can be easily filled into the cavity of the mold, are preferable.

本発明の予備発泡粒子は、前述した発泡性ポリスチレン系樹脂粒子を予備発泡させてなるものなので、該予備発泡粒子を用いて製造したポリスチレン系樹脂発泡成形体は、ニクロムカットによる融けしろを小さくすることができ、製品の歩留まりを改善することができ、またニクロムカット時の融けしろの差が粒子内及び粒子間で無くなり、凹凸がなく平滑なカット面を得ることができる。   Since the pre-expanded particles of the present invention are obtained by pre-expanding the above-mentioned expandable polystyrene resin particles, the polystyrene resin foam-molded article produced using the pre-expanded particles reduces the melting margin due to nichrome cut. Thus, the yield of the product can be improved, and the difference in meltability at the time of nichrome cutting is eliminated within and between the particles, so that a smooth cut surface without unevenness can be obtained.

本発明は、前述した予備発泡粒子を型内発泡成形して得られたポリスチレン系樹脂発泡成形体(以下、発泡成形体と記す。)とその製造方法を提供する。
前述した予備発泡粒子を発泡成形体とするには、前述した予備発泡粒子を通常24時間程度保持して熟成させ、その後、予備発泡粒子を成形型のキャビティ内に充填し、加熱して型内発泡成形させ、予備発泡粒子同士を融着一体化させることによって所望形状を有する発泡成形体を得ることができる。この型内発泡成形は、例えば、蒸気圧0.04〜0.1MPa程度の水蒸気を成形型内に導入することによって行うことができる。
The present invention provides a polystyrene resin foam molded article (hereinafter referred to as a foam molded article) obtained by in-mold foam molding of the above-mentioned pre-expanded particles and a method for producing the same.
In order to make the above-mentioned pre-expanded particles into a foam-molded product, the above-mentioned pre-expanded particles are usually held for about 24 hours and aged, and then the pre-expanded particles are filled into the mold cavity and heated to be heated in the mold. A foam-molded article having a desired shape can be obtained by foam-molding and fusing and pre-expanding particles together. This in-mold foam molding can be performed, for example, by introducing water vapor having a vapor pressure of about 0.04 to 0.1 MPa into the mold.

本発明の発泡成形体は、密度が0.0125〜0.05g/cmの範囲内であり、0.015〜0.025g/cmの範囲がより好ましい。該発泡成形体の密度が0.0125g/cmより小さいと、発泡成形体の収縮が発生し、良好な発泡成形体が得られない。また密度が0.05g/cmより大きいと、発泡倍数が低いために、発泡成形体の質量が増加するので好ましくない。 The foamed molded product of the present invention has a density in the range of 0.0125 to 0.05 g / cm 3 , and more preferably in the range of 0.015 to 0.025 g / cm 3 . When the density of the foamed molded product is less than 0.0125 g / cm 3 , shrinkage of the foamed molded product occurs and a good foamed molded product cannot be obtained. On the other hand, if the density is larger than 0.05 g / cm 3 , the expansion ratio is low, and the mass of the foamed molded product increases, which is not preferable.

前述のように得られた発泡成形体は、後述する建材用ブロックカット材(発泡体スライス品)などとして好適に用いられるが、これに限定されず、車輛用バンパーの芯材、ドア内装緩衝材等の車輛用緩衝材、電子部品、各種工業資材、食品等の搬送容器等の各種用途に用いることができる。   The foamed molded body obtained as described above is suitably used as a building material block-cut material (foam sliced product), which will be described later, but is not limited thereto, and is a vehicle bumper core material and door interior cushioning material. It can be used for various applications such as vehicle cushioning materials such as automobiles, electronic parts, various industrial materials, food containers and the like.

本発明の発泡成形体は、前記予備発泡粒子を型内発泡成形したものなので、ニクロムカットによる融けしろを小さくすることができ、製品の歩留まりを改善することができ、またニクロムカット時の融けしろの差が粒子内及び粒子間で無くなり、凹凸がなく平滑なカット面を得ることができる。   Since the foamed molded product of the present invention is obtained by in-mold foam molding of the pre-expanded particles, it is possible to reduce the melting margin due to nichrome cutting, improve the product yield, and the melting margin during nichrome cutting. Difference between the particles and between the particles is eliminated, and a smooth cut surface without irregularities can be obtained.

本発明は、前述した発泡成形体を所望形状にニクロムカットして得られたポリスチレン系樹脂発泡体スライス品(以下、スライス品と記す。)及びその製造方法を提供する。   The present invention provides a polystyrene resin foam sliced product (hereinafter referred to as a sliced product) obtained by nichrome cutting the above-mentioned foamed molded product into a desired shape and a method for producing the same.

発泡成形体をニクロムカットする手法は、ニクロム線などの電気抵抗加熱線に通電、加熱し、それを発泡成形体に近接又は接触せしめ、発泡成形体を所望の形状にカットする従来周知の手法を用いることができる。電気抵抗加熱線は、直線状の他、曲線状、円環状、楕円環状、三角形や四角形などの角環状、円弧状などの様々な形状の線材を単独で、又は同種の線材を多数配列して、又は多種の線材を適宜組み合わせて用いることができ、ニクロムカットして得られたスライス品の形状も、板状に限定されず、様々な形状とすることができる。   The method of cutting the foam molded body with nichrome is the conventional well-known method of cutting the foam molded body into a desired shape by energizing and heating an electric resistance heating wire such as a nichrome wire and bringing it close to or in contact with the foam molded body. Can be used. The electric resistance heating wire is not only linear, but also various shapes such as curved, circular, elliptical, triangular, quadrangular, circular, arc, etc., or a large number of the same kind of wires are arranged. Alternatively, various wire rods can be used in appropriate combination, and the shape of the sliced product obtained by cutting nichrome is not limited to a plate shape, and can be various shapes.

本発明のスライス品は、ニクロムカット面における亀甲高さ(測定方法は後述する。)が50μm以下であることが好ましい。この亀甲高さが50μm以下であれば、ニクロムカット面の凹凸が小さく、綺麗な平滑面に見える。この亀甲高さは、40μm以下であることが好ましく、30μm以下であることがより好ましい。一方、この亀甲高さが50μmを超えると、カット面の凹凸が大きくなり、ザラザラした感じになり、見栄えが悪くなる。また亀甲高さが50μmを超えると、このニクロムカット面に外板などの物品を接着固定する際に、十分な接着強度が得られなくなる。   The sliced product of the present invention preferably has a turtle shell height (measurement method will be described later) on the nichrome cut surface of 50 μm or less. If the turtle shell height is 50 μm or less, the unevenness of the nichrome cut surface is small and the surface looks beautiful and smooth. The turtle shell height is preferably 40 μm or less, and more preferably 30 μm or less. On the other hand, when the turtle shell height exceeds 50 μm, the unevenness of the cut surface becomes large, and it becomes rough and looks bad. If the turtle shell height exceeds 50 μm, sufficient adhesive strength cannot be obtained when an article such as an outer plate is bonded and fixed to the nichrome cut surface.

また、本発明のスライス品は、ニクロムカット面における融けしろ(測定方法は後述する。)の量が3%未満であることが好ましい。この融けしろが3%未満であれば、ニクロムカットによる厚み変化が小さくなり、所定寸法のスライス品を安定して生産でき、また製品の歩留まりを改善することがでる。一方、この融けしろが3%を超えると、製品の歩留まりが悪化する。   The sliced product of the present invention preferably has an amount of melting margin (measurement method will be described later) on the nichrome cut surface of less than 3%. If the melting margin is less than 3%, the thickness change due to the nichrome cut becomes small, and a sliced product having a predetermined dimension can be stably produced, and the yield of the product can be improved. On the other hand, when the margin exceeds 3%, the product yield deteriorates.

本発明のスライス品は、前記ポリスチレン系樹脂発泡成形体を所望の形状にニクロムカットしたものなので、ニクロムカットによる融けしろを小さくすることができ、製品の歩留まりを改善することができ、またニクロムカット時の融けしろの差が粒子内及び粒子間で無くなり、凹凸がなく平滑なカット面を得ることができる。
以下、実施例により本発明の効果を実証する。
Since the sliced product of the present invention is obtained by cutting the polystyrene resin foam molded body into a desired shape with nichrome cut, it is possible to reduce the melting margin due to the nichrome cut, improve the yield of the product, and also cut the nichrome. The difference in melting time is eliminated between the particles and between the particles, and a smooth cut surface without irregularities can be obtained.
Hereinafter, the effects of the present invention will be demonstrated by examples.

(実施例1)
[懸濁重合]
内容積100リットルの攪拌機付オートクレーブにリン酸三カルシウム(大平化学社製)120g、ドデシルベンゼンスルホン酸ソーダ4g、過酸化ベンゾイル(純度75%)140g、t−ブチルパーオキシ−2−エチルヘキシルモノカーボネート30g、イオン交換水40kg及びスチレン単量体40kgを投入した後、100rpmの撹拌下で溶解及び分散させて懸濁液を形成した。
引き続き、攪拌羽を100rpmで撹拌しながらオートクレーブ内の温度を90℃まで昇温した後、90℃で6時間保持した。
その後、さらにオートクレーブ内の温度を120℃まで昇温し、120℃で2時間保持した後、オートクレーブ内の温度を25℃まで冷却し、オートクレーブから内容物を取り出し、脱水・乾燥・分級して粒子径が0.5〜0.7mmで重量平均分子量が30万のスチレン系樹脂粒子を得た。
なお、上記工程で使用の原料及び添加剤は、何れを先に投入しても良い。
また、上記工程で使用の原料及び添加剤は、そのまま投入しても、希釈・溶解して投入してもよい。
Example 1
[Suspension polymerization]
In an autoclave with a stirrer with an internal volume of 100 liters, 120 g of tricalcium phosphate (manufactured by Ohira Chemical Co., Ltd.), 4 g of sodium dodecylbenzenesulfonate, 140 g of benzoyl peroxide (purity 75%), 30 g of t-butylperoxy-2-ethylhexyl monocarbonate Then, 40 kg of ion exchange water and 40 kg of styrene monomer were added, and then dissolved and dispersed under stirring at 100 rpm to form a suspension.
Subsequently, the temperature in the autoclave was raised to 90 ° C. while stirring the stirring blade at 100 rpm, and then held at 90 ° C. for 6 hours.
After that, the temperature inside the autoclave is further raised to 120 ° C. and held at 120 ° C. for 2 hours, then the temperature inside the autoclave is cooled to 25 ° C., the contents are taken out from the autoclave, dehydrated, dried and classified. Styrenic resin particles having a diameter of 0.5 to 0.7 mm and a weight average molecular weight of 300,000 were obtained.
In addition, any of the raw materials and additives used in the above steps may be added first.
Further, the raw materials and additives used in the above steps may be added as they are, or may be diluted and dissolved.

[シード重合]
次いで、100リットルの攪拌機付オートクレーブに純水30kg、ドデシルベンゼンスルホン酸ソーダ4g、ピロリン酸マグネシウム100gを入れ、さらに上記記載の粒子径0.5〜0.7mmで重量平均分子量が30万のポリスチレン核粒子11kg(25質量部)を加えて攪拌し懸濁させた。
次いで、予め用意しておいた乳濁液を75℃に保持した反応器に添加した。この乳濁液は、純水6kg、ドデシルベンゼンスルホン酸ソーダ2g、ピロリン酸マグネシウム20gの分散液に、重合開始剤の過酸化ベンゾイル(純度75%)88g、t−ブチルパーオキシ−2−エチルヘキシルモノカーボネート50gを溶解したスチレン単量体5kgを加え、ホモミキサーで攪拌して乳濁化させたものである。その後、ポリスチレン系樹脂粒子中にスチレン単量体と重合開始剤とがよく吸収されるように30分間保持し、保持した直後からスチレン単量体28kgを165分かけて連続的に滴下した。滴下が終了した時点において、反応器中に添加されたスチレン単量体は33kg即ち75質量部であり、ポリスチレン系樹脂粒子と添加されたスチレン単量体の合計量は100質量部になる。反応器の温度としては、上記75℃で30分間保持した後、0.2℃/分の割合で90℃まで昇温し、その後は90℃を保持した。
次に、スチレン単量体の滴下が終了してから30分後に、1℃/分の割合で120℃まで昇温し、90分間保持した。
[Seed polymerization]
Subsequently, 30 kg of pure water, 4 g of sodium dodecylbenzenesulfonate, and 100 g of magnesium pyrophosphate are placed in a 100 liter autoclave equipped with a stirrer, and further a polystyrene nucleus having a particle size of 0.5 to 0.7 mm and a weight average molecular weight of 300,000 as described above. 11 kg (25 parts by mass) of particles were added and stirred and suspended.
The previously prepared emulsion was then added to the reactor maintained at 75 ° C. This emulsion was prepared by dispersing 88 kg of benzoyl peroxide (purity 75%) as a polymerization initiator in a dispersion of 6 kg of pure water, 2 g of sodium dodecylbenzenesulfonate and 20 g of magnesium pyrophosphate, t-butylperoxy-2-ethylhexyl mono 5 kg of styrene monomer in which 50 g of carbonate is dissolved is added, and the mixture is stirred and emulsified with a homomixer. Thereafter, the polystyrene resin particles were held for 30 minutes so that the styrene monomer and the polymerization initiator were well absorbed, and 28 kg of styrene monomer was continuously dropped over 165 minutes immediately after the holding. When the dropping is completed, the amount of styrene monomer added to the reactor is 33 kg, that is, 75 parts by mass, and the total amount of polystyrene resin particles and added styrene monomer is 100 parts by mass. The reactor temperature was maintained at 75 ° C. for 30 minutes, then increased to 90 ° C. at a rate of 0.2 ° C./min, and then maintained at 90 ° C.
Next, 30 minutes after the completion of dropping of the styrene monomer, the temperature was raised to 120 ° C. at a rate of 1 ° C./min, and held for 90 minutes.

[含浸]
その後1℃/分の割合で90℃まで冷却後、予め調製しておいた乳濁液を反応器に添加した。この乳濁液は、純水2kg、ドデシルベンゼンスルホン酸ソーダ0.8gの分散液に、アジピン酸ジイソブチル(田岡化学工業株式会社製 商品名:DI4A)308gを加え、ホモミキサーで攪拌して乳濁化したものである。
この乳濁液を添加してから30分後に、発泡剤として、ブタン(イソブタン/ノルマルブタン=30/70)2640gとペンタン(イソペンタン/ノルマルペンタン=20/80) 1100gとを窒素加圧してオートクレーブ内に30分間で圧入し、その状態で4時間保持した後、オートクレーブ内の温度を25℃まで冷却し、オートクレーブから内容物を取り出し、脱水・乾燥・分級して粒子径が0.85〜1.2mmで重量平均分子量が34.8万の発泡性ポリスチレン系樹脂粒子を得た。
[Impregnation]
Thereafter, after cooling to 90 ° C. at a rate of 1 ° C./min, an emulsion prepared in advance was added to the reactor. To this emulsion, 308 g of diisobutyl adipate (trade name: DI4A, manufactured by Taoka Chemical Co., Ltd.) was added to a dispersion of 2 kg of pure water and 0.8 g of sodium dodecylbenzenesulfonate, and the mixture was agitated with a homomixer. It has become.
Thirty minutes after the addition of this emulsion, 2640 g of butane (isobutane / normal butane = 30/70) and 1100 g of pentane (isopentane / normal pentane = 20/80) were pressurized with nitrogen in the autoclave. For 30 minutes, and kept in that state for 4 hours. Then, the temperature in the autoclave is cooled to 25 ° C., the contents are taken out from the autoclave, dehydrated, dried, and classified to obtain a particle size of 0.85 to 1. Expandable polystyrene resin particles having a weight average molecular weight of 3480, 2 mm were obtained.

(実施例2)
含浸工程で、発泡剤を圧入する前に、反応器に難燃剤TBCO(第一エフアール社製、商品名ピロガードFR−200)440g及び難燃助剤DCP(日本油脂社製、商品名SP−270)132gを加えた以外は、実施例1と同様の方法で行った。
(Example 2)
In the impregnation step, before the foaming agent is injected, 440 g of flame retardant TBCO (trade name: Piroguard FR-200, manufactured by Daiichi FAR Co., Ltd.) and flame retardant aid DCP (product name: SP-, manufactured by Nippon Oil & Fats Co., Ltd.) 270) Performed in the same manner as in Example 1 except that 132 g was added.

(実施例3)
シード重合工程において、過酸化べンゾイル(純度75%)を120gに変更し、連続で滴下するスチレン単量体に、予めジビニルベンゼン3.3gを加えて溶解させ、含浸工程で発泡剤を圧入する前に、反応器に難燃剤TBCO440g及び難燃助剤DCP132gを加えた以外は、実施例1と同様の方法で行った。
(Example 3)
In the seed polymerization step, benzoyl peroxide (purity 75%) was changed to 120 g, and 3.3 g of divinylbenzene was added in advance to the styrene monomer that was continuously added dropwise, and the blowing agent was injected in the impregnation step. Previously, the same procedure as in Example 1 was performed except that 440 g of flame retardant TBCO and 132 g of flame retardant aid DCP were added to the reactor.

(実施例4)
含浸工程で、過酸化べンゾイル(純度75%)を145gに変更し、連続で滴下するスチレン単量体に予めジビニルベンゼン9.9gを加えて溶解させて135分かけて連続的に滴下し、発泡剤を圧入する前に、反応器に難燃剤TBCO440g及び難燃助剤DCP132gを加えた以外は実施例1と同様の方法で行った。
Example 4
In the impregnation step, benzoyl peroxide (purity 75%) was changed to 145 g, 9.9 g of divinylbenzene was added in advance to the styrene monomer continuously dropped, and dropped continuously over 135 minutes, The same procedure as in Example 1 was performed, except that 440 g of flame retardant TBCO and 132 g of flame retardant aid DCP were added to the reactor before the foaming agent was injected.

(比較例1)
シード重合工程で、重合開始剤の過酸化ベンゾイル(純度75%)を145g、滴下終了温度を108℃とし、75℃から108℃まで0.2℃/分の割合で昇温した以外は、実施例1と同様の方法で行った。
(Comparative Example 1)
In the seed polymerization process, except that the polymerization initiator benzoyl peroxide (purity 75%) was 145 g, the dropping end temperature was 108 ° C., and the temperature was increased from 75 ° C. to 108 ° C. at a rate of 0.2 ° C./min. The same method as in Example 1 was used.

(比較例2)
含浸工程で、発泡剤を圧入する前に、反応器に難燃剤TBCO440g及び難燃助剤DCP132gを加えた以外は、比較例1と同様の方法で行った。
(Comparative Example 2)
In the impregnation step, the same procedure as in Comparative Example 1 was performed except that 440 g of the flame retardant TBCO and 132 g of the flame retardant assistant DCP were added to the reactor before the foaming agent was injected.

(比較例3)
シード重合工程で、過酸化べンゾイル(純度75%)を132gに変更した以外は、実施例2と同様の方法で行った。
(Comparative Example 3)
The same procedure as in Example 2 was performed, except that benzoyl peroxide (purity 75%) was changed to 132 g in the seed polymerization step.

(比較例4)
シード重合工程で、過酸化べンゾイル(純度75%)を160gに変更した以外は、実施例3と同様の方法で行った。
(Comparative Example 4)
The same procedure as in Example 3 was performed except that in the seed polymerization step, benzoyl peroxide (purity 75%) was changed to 160 g.

〔ブレンド工程〕
前述した実施例1〜4、比較例1〜4においてそれぞれ製造した発泡性ポリスチレン系樹脂粒子40kgと、表面処理剤としてのポリエチレングリコール20g及びステアリン酸亜鉛60g、脂肪酸トリグリセライド(理研ビタミン社製 商品名:リケマールVT−50)40g、脂肪酸モノグリセライド(理研ビタミン社製 商品名:リケマールS−100P)20gとをタンブラーミキサーに投入し、30分間撹拌し、各発泡性ポリスチレン系樹脂粒子にそれぞれ表面処理剤を被覆した。
[Blend process]
40 kg of expandable polystyrene resin particles produced in Examples 1 to 4 and Comparative Examples 1 to 4 described above, 20 g of polyethylene glycol as a surface treatment agent and 60 g of zinc stearate, fatty acid triglyceride (manufactured by Riken Vitamin Co., Ltd. 40 g of Riquemar VT-50) and 20 g of fatty acid monoglyceride (trade name: Riquemar S-100P, manufactured by Riken Vitamin Co., Ltd.) were placed in a tumbler mixer, stirred for 30 minutes, and each expandable polystyrene resin particle was coated with a surface treatment agent. did.

〔予備発泡工程〕
前記ブレンド工程後の各発泡性ポリスチレン系樹脂粒子5.8kgを、それぞれ15℃の保冷庫にて48時間保管後、特許庁公報 57(1982)−133〔3347〕周知・慣用技術集(発泡成形)P.39記載の発泡層上面検出器までの容積量が350リットルである円筒型バッチ式加圧予備発泡機に投入し、蒸気により2分間加熱し、実施例1〜4及び比較例1〜4のそれぞれの予備発泡粒子を得た。それぞれの予備発泡粒子の嵩密度は0.0167g/cm、嵩発泡倍数は60倍であった。
発泡粒子の嵩密度と嵩発泡倍数は、次の様にして測定した。
<嵩密度の測定方法>
嵩密度は予備発泡粒子を試料としてメスシリンダー内に自然落下させたのち、メスシリンダーの底をたたいて試料容積を一定にさせ、その容積と質量を測定し次式により算出した。
嵩密度(g/cm)=試料質量(g)/メスシリンダー中の試料容積(cm
<嵩発泡倍数の測定方法>
嵩発泡倍数は予備発泡粒子を試料としてメスシリンダー内に自然落下させたのち、メスシリンダーの底をたたいて試料容積を一定にさせ、その容積と質量を測定し次式により算出した。樹脂比重は、スチレン系樹脂の場合1.0とした。
嵩発泡倍数(倍)=メスシリンダー中の試料容積(ml)/試料質量(g)×樹脂比重
[Pre-foaming process]
5.8 kg of each expandable polystyrene resin particle after the blending process is stored in a refrigerator at 15 ° C. for 48 hours, and then published by JPO Gazette 57 (1982) -133 [3347]. P. No. 39 is introduced into a cylindrical batch type pressure pre-foaming machine having a volume of up to 350 liters up to the foam layer upper surface detector, heated for 2 minutes with steam, and each of Examples 1-4 and Comparative Examples 1-4 The pre-expanded particles were obtained. Each pre-expanded particle had a bulk density of 0.0167 g / cm 3 and a bulk expansion ratio of 60 times.
The bulk density and the bulk expansion ratio of the expanded particles were measured as follows.
<Method for measuring bulk density>
The bulk density was calculated by the following formula after pre-expanded particles were naturally dropped into a graduated cylinder and then the bottom of the graduated cylinder was hit to make the sample volume constant.
Bulk density (g / cm 3 ) = Sample mass (g) / Sample volume in graduated cylinder (cm 3 )
<Measurement method of bulk expansion ratio>
The bulk foaming factor was calculated by the following equation by allowing the pre-expanded particles to fall naturally into the graduated cylinder, then hitting the bottom of the graduated cylinder to make the sample volume constant, measuring the volume and mass. The specific gravity of the resin was 1.0 in the case of styrene resin.
Bulk foam multiple (times) = sample volume (ml) / sample mass (g) x resin specific gravity in graduated cylinder

〔成形工程〕
前記実施例1〜4及び比較例1〜4のそれぞれの予備発泡粒子を室温雰囲気下で24時間放置後、キャビティのサイズ:高さ1840mm、幅930mm、奥行530mmの成形型を有するブロック成形機(笠原工業社製 PEONY‐205DS)を用い、成形型のキャビティ内に前記予備発泡粒子を充填し、0.07MPa(ゲージ圧)の蒸気圧で20秒間加熱し、次いで成形型内圧力が−0.01MPaになるまで冷却し、成形型から離型し、ブロック発泡成形体を得る成形工程を、前記実施例1〜4及び比較例1〜4のそれぞれの予備発泡粒子について実施し、実施例1〜4及び比較例1〜4のそれぞれのブロック発泡成形体を製造した。それぞれのブロック発泡成形体の密度は0.0167g/cm、発泡倍数は60倍であった。その後、それぞれのブロック発泡成形体を、70℃乾燥室に3日間保管した。
発泡成形体の密度と発泡倍数は、次の様にして測定した。
<密度の測定方法>
発泡成形体の密度は試験片(例50×50×25mm)の寸法と質量を有効数字3桁以上になるように測定し、次式により算出した。
密度(g/cm)=試験片質量(g)/試験片体積(cm
<発泡倍数の測定方法>
発泡成形体の発泡倍数は試験片(例50×50×25mm)の寸法と質量を有効数字3桁以上になるように測定し、次式により算出した。樹脂比重は、スチレン系樹脂の場合1.0とした。
発泡倍数(倍)=試験片体積(cm)/試験片質量(g)×樹脂比重
[Molding process]
Each of the pre-expanded particles of Examples 1 to 4 and Comparative Examples 1 to 4 was allowed to stand in a room temperature atmosphere for 24 hours, and then a block molding machine having a mold having a cavity size: height 1840 mm, width 930 mm, depth 530 mm ( PEONY-205DS manufactured by Kasahara Kogyo Co., Ltd.), the pre-expanded particles were filled into the mold cavity, heated at a vapor pressure of 0.07 MPa (gauge pressure) for 20 seconds, and then the pressure in the mold was -0. Cooling to 01 MPa, releasing from the mold, and performing the molding step to obtain a block foamed molded body was performed on each pre-expanded particle of Examples 1-4 and Comparative Examples 1-4, and Examples 1- 4 and Comparative Examples 1 to 4 were produced. The density of each block foam molded article was 0.0167 g / cm 3 , and the expansion ratio was 60 times. Then, each block foaming molding was stored in a 70 degreeC drying room for 3 days.
The density and expansion ratio of the foamed molded product were measured as follows.
<Density measurement method>
The density of the foamed molded product was measured by measuring the size and mass of a test piece (eg, 50 × 50 × 25 mm) so that it was 3 or more significant digits, and was calculated by the following formula.
Density (g / cm 3 ) = Test piece mass (g) / Test piece volume (cm 3 )
<Measurement method of expansion ratio>
The expansion ratio of the foamed molded product was measured by measuring the size and mass of a test piece (example 50 × 50 × 25 mm) so that it was 3 or more significant digits, and was calculated by the following formula. The specific gravity of the resin was 1.0 in the case of styrene resin.
Foaming factor (times) = test piece volume (cm 3 ) / test piece mass (g) × resin specific gravity

〔ニクロムカット工程〕
ブロック成形体の固定側(長さ1840mm、幅930mmの平面)を下にしてニクロムカット機の台に置き、0.4mm径のニクロム線を50mm間隔で平行に10本張設し、ブロック送り速度600mm/分、電流3A/本の条件にてニクロムカットを行い、実施例1〜4及び比較例1〜4のそれぞれの平板形状のスライス品を得た。
[Nichrome cutting process]
Place the block molding on the base of the nichrome cutting machine with the fixed side (length 1840mm, width 930mm plane) down, and stretch ten 0.4mm diameter nichrome wires in parallel at 50mm intervals. Nichrome cutting was performed under the conditions of 600 mm / min and current of 3 A / line to obtain flat plate slices of Examples 1 to 4 and Comparative Examples 1 to 4, respectively.

実施例1〜4及び比較例1〜4のそれぞれの発泡性ポリスチレン系樹脂粒子及び予備発泡粒子を用い、以下の通り重量平均分子量(粒子全体の重量平均分子量、予備発泡粒子の表層部の重量平均分子量)を測定し、得られた値を前述した式(1)に代入して分子量の低下率を算出した。結果を表1に示す。
また、前述したように製造した実施例1〜4及び比較例1〜4のそれぞれの発泡性ポリスチレン樹脂粒子を用い、以下の通り芳香族有機化合物含有量の測定を実施した。
また、前述したように製造した実施例1〜4及び比較例1〜4のそれぞれのブロック成形体について、以下の通り融着率の測定を実施した。
また、前述したように製造した実施例1〜4及び比較例1〜4のそれぞれのスライス品について、ニクロムカット面の亀甲高さの測定、融けしろの評価を実施し、比較した。これらの各項目の測定、評価は、以下の通り実施した。結果を表1にまとめて示す。
Using each of the expandable polystyrene resin particles and pre-expanded particles of Examples 1 to 4 and Comparative Examples 1 to 4, the weight average molecular weight (weight average molecular weight of the entire particle, weight average of the surface layer portion of the pre-expanded particles) (Molecular weight) was measured, and the obtained value was substituted into the above-described formula (1) to calculate the reduction rate of the molecular weight. The results are shown in Table 1.
Moreover, using each expandable polystyrene resin particle of Examples 1-4 and Comparative Examples 1-4 manufactured as mentioned above, the aromatic organic compound content was measured as follows.
Moreover, about each block molded object of Examples 1-4 and Comparative Examples 1-4 manufactured as mentioned above, the fusion rate was measured as follows.
Moreover, about each sliced product of Examples 1-4 and Comparative Examples 1-4 manufactured as mentioned above, the measurement of the turtle shell height of a nichrome cut surface, and evaluation of the melting margin were implemented and compared. Measurement and evaluation of each of these items were performed as follows. The results are summarized in Table 1.

<分子量の測定>
・粒子全体:
実施例1〜4及び比較例1〜4のそれぞれの発泡性ポリスチレン系樹脂粒子を約5mg採取し、このサンプルをテトラヒドロフラン(THF)1mLに浸漬して24時間室温に保管する。非水系0.45μmクロマトディスクで濾過後、Waters社製 HPLC(Detector 484,Pump 510)を用いてポリスチレン換算分子量を測定した。その測定条件は、カラムが昭和電工社製・Shodex GPC K−806L(φ8.0×300mm)2本を用い、カラム温度(40℃)、移動相(THF)、移動相流量(1.2mL/min)、注入・ポンプ温度(室温)、検出(UV254nm)、注入量(50μL)、検量線用標準PS(昭和電工社製(Shodex)分子量1,030,000と東ソー社製分子量5,480,000と3,840,000と355,000と102,000と37,900と9,100と2,630と495)とした。
・表層部
実施例1〜4及び比較例1〜4のそれぞれの予備発泡粒子の直径Dに対して、直径の1/16の位置を剃刀刃にてスライスした。スライス方法の一例として、次の方法で行った(図1参照)。まず直径の1/2の位置を剃刀にて2等分にスライスした。次に半球状の径1/2Dに対して、1/2の位置を剃刀刃にて2等分にスライスした。さらに径1/4Dに対して、1/2の位置を剃刀刃にて2等分にスライスした。最後に径1/8Dに対して、1/2の位置を剃刀刃にてスライスし、径1/16Dのサンプルを得た。この作業をもう半分の半球についても実施した。この作業を測定に必要な5mgが得られるまで繰り返してサンプリングを行い、その後粒子全体に記載した同様の方法にて測定を実施した。
<Measurement of molecular weight>
・ Whole particles:
About 5 mg of each expandable polystyrene resin particle of each of Examples 1 to 4 and Comparative Examples 1 to 4 is collected, and this sample is immersed in 1 mL of tetrahydrofuran (THF) and stored at room temperature for 24 hours. After filtration through a non-aqueous 0.45 μm chromatodisc, the molecular weight in terms of polystyrene was measured using HPLC (Detector 484, Pump 510) manufactured by Waters. The measurement conditions were as follows: two columns, Shodex GPC K-806L (φ8.0 × 300 mm) manufactured by Showa Denko KK, column temperature (40 ° C.), mobile phase (THF), mobile phase flow rate (1.2 mL / min), injection / pump temperature (room temperature), detection (UV254 nm), injection amount (50 μL), standard PS for calibration curve (Showa Denko (Shodex) molecular weight 1,030,000, Tosoh molecular weight 5,480,000, 3,840,000, 355,000 and 102,000 37,900, 9,100, 2,630 and 495).
-Surface layer part With respect to the diameter D of each pre-expanded particle of Examples 1-4 and Comparative Examples 1-4, the position of 1/16 of the diameter was sliced with the razor blade. As an example of the slicing method, the following method was used (see FIG. 1). First, a half position of the diameter was sliced into two equal parts with a razor. Next, with respect to the hemispherical diameter 1 / 2D, a half position was sliced into two equal parts with a razor blade. Furthermore, with respect to the diameter 1 / 4D, the position of 1/2 was sliced into two equal parts with a razor blade. Finally, a half position with respect to the diameter 1 / 8D was sliced with a razor blade to obtain a sample with a diameter 1 / 16D. This was done for the other half of the hemisphere. This operation was repeated until 5 mg necessary for measurement was obtained, and then sampling was performed, and then measurement was performed by the same method described for the entire particle.

<芳香族有機化合物含有量の測定>
発泡性ポリスチレン樹脂粒子1gを精秤し、この精秤した発泡性ポリスチレン樹脂粒子に0.1体積%のシクロペンタノールを含有するジメチルホルムアミド溶液1mLを内部標準液として加えた後、更にジメチルホルムアミド溶液にジメチルホルムアミドを加えて25mLとして測定溶液を作製し、この測定溶液1.8μLを230℃の試料気化室に供給し、下記測定条件にてガスクロマトグラフ(島津製作所製、商品名GC−14A)で検出された各芳香族有機化合物のチャートを得た。そして予め測定しておいた、各芳香族有機化合物の検量線に基づいて、各チャートから芳香族有機化合物量をそれぞれ算出することによって、発泡性ポリスチレン粒子中の芳香族有機化合物量を算出した。
検出器 :FID
カラム :ジーエルサイエンス製 (3mmφ×2.5m)
液相;PEG-20M PT 25%
担体;Chromosorb W AW−DMCS
メッシュ:60/80
カラム温度:100℃
検出器温度:230℃
注入口温度:180℃
キャリアーガス(窒素)
キャリヤーガス流量(40mL/min)
<Measurement of aromatic organic compound content>
1 g of expandable polystyrene resin particles are precisely weighed, and 1 mL of a dimethylformamide solution containing 0.1% by volume of cyclopentanol is added as an internal standard solution to the precisely measured expandable polystyrene resin particles, and then further dimethylformamide solution. Dimethylformamide was added to 25 mL to prepare a measurement solution, 1.8 μL of this measurement solution was supplied to a 230 ° C. sample vaporization chamber, and a gas chromatograph (manufactured by Shimadzu Corporation, trade name GC-14A) under the following measurement conditions. A chart of each detected aromatic organic compound was obtained. The amount of aromatic organic compound in the expandable polystyrene particles was calculated by calculating the amount of aromatic organic compound from each chart based on the calibration curve of each aromatic organic compound measured in advance.
Detector: FID
Column: GL Sciences (3mmφ × 2.5m)
Liquid phase: PEG-20M PT 25%
Carrier: Chromosorb W AW-DMCS
Mesh: 60/80
Column temperature: 100 ° C
Detector temperature: 230 ° C
Inlet temperature: 180 ° C
Carrier gas (nitrogen)
Carrier gas flow rate (40mL / min)

<融着率の測定>
ニクロムカットにより得た下から6枚目のブロック成形体(長さ1840mm、幅930mm、厚さ50mm)の中心に沿ってカッターナイフで深さ約5mmの切り込み線を入れた後、この切り込み線に沿って発泡成形体を手で二分割し(長さ920mm、幅930mm、厚さ50mm)、その破断面における発泡粒子について、100〜150個の任意の範囲について粒子内で破断している粒子の数(a)と粒子どうしの界面で破断している粒子の数(b)とを数え、式[(a)/((a)+(b))]×100に代入して得られた値を融着率(%)とした。融着率70%以上を○、70%未満を×として評価した。
<Measurement of fusion rate>
A cutting line having a depth of about 5 mm was made with a cutter knife along the center of the sixth block molded body (length 1840 mm, width 930 mm, thickness 50 mm) obtained from the nichrome cut. The foamed molded body is divided into two parts by hand (length: 920 mm, width: 930 mm, thickness: 50 mm), and the foamed particles in the fracture surface of the particles that break in the particles in an arbitrary range of 100 to 150 A value obtained by counting the number (a) and the number (b) of particles broken at the interface between the particles and substituting them into the formula [(a) / ((a) + (b))] × 100 Was the fusion rate (%). Evaluation was made with a fusion rate of 70% or more as ◯ and less than 70% as x.

<ニクロムカット面の亀甲高さ>
走査型電子顕微鏡(日本電子社製 JEOL JSM−6360LV)にて、ニクロムカット面を垂直方向に30倍に拡大し、図2に示すように、粒子のくぼみ深さを10粒子について測長し、その平均値を亀甲高さ測定値とした。
判定:
○ :亀甲高さ測定値が50μm以下であり、凹凸がなく表面が平滑で良好である。
× :亀甲高さ測定値が50μmを超えており、凹凸がやや見られ表面の平滑がやや劣る。
××:亀甲高さ測定値が100μmを超えており、凹凸が見られ表面の平滑がかなり劣る。
<Tortoiseshell height of Nichrome cut surface>
With a scanning electron microscope (JEOL JSM-6360LV, manufactured by JEOL Ltd.), the nichrome cut surface was enlarged 30 times in the vertical direction, and as shown in FIG. 2, the indentation depth of the particles was measured for 10 particles, The average value was taken as the measured value of the turtle shell height.
Judgment:
○: Tortoise shell height measurement value is 50 μm or less, no irregularities, smooth and good surface
X: Tortoise shell height measurement value exceeds 50 μm, unevenness is slightly seen and surface smoothness is slightly inferior.
XX: Tortoise shell height measurement value exceeds 100 μm, irregularities are seen and the surface smoothness is considerably inferior.

<融けしろの評価>
ニクロムカットにて得られたスライス品について、下記の評価を行った。
融けしろ(%)=100−得られたスライス品を重ねた高さ(mm)/ニクロムカット前の高さ(530mm)×100
○:3%未満、融けしろの量が少なく良好である。
×:3%以上、融けしろの量が多く、歩留まりが劣る。
として評価した。
<Evaluation of melting margin>
The following evaluation was performed about the sliced product obtained by the nichrome cut.
Melting margin (%) = 100-height (mm) of the obtained sliced product / height before nichrome cutting (530 mm) × 100
○: Less than 3%, good amount of margin for melting.
X: 3% or more, the amount of melting is large, and the yield is inferior.
As evaluated.

Figure 2007246606
Figure 2007246606

表1の結果から、本発明に係る実施例1〜4のスライス品は、融けしろが2.1%以下と小さく、スライス品製造時の歩留まりが高い。また実施例1〜4のスライス品は、ニクロムカット面の亀甲高さが31μm以下と小さく、カット面が平滑で、綺麗な外観であった。
また、表1には記載していないが、実施例1〜4及び比較例1〜4の各発泡性ポリスチレン樹脂粒子について芳香族有機化合物含有量の測定を行った結果、スチレン系単量体、エチルベンゼン、イソプロピルベンゼン、ノルマルプロピルベンゼン、キシレン、トルエンからなる芳香族有機化合物の含有量の総和は500ppm未満であり、安全性が高いことが確認された。
From the results shown in Table 1, the sliced products of Examples 1 to 4 according to the present invention have a small melting margin of 2.1% or less and a high yield when manufacturing the sliced products. In addition, the sliced products of Examples 1 to 4 had a beautiful appearance with a turtle shell height of a nichrome cut surface as small as 31 μm or less, a smooth cut surface.
Moreover, although not described in Table 1, as a result of measuring aromatic organic compound content about each expandable polystyrene resin particle of Examples 1-4 and Comparative Examples 1-4, a styrene-type monomer, The total content of aromatic organic compounds composed of ethylbenzene, isopropylbenzene, normal propylbenzene, xylene, and toluene was less than 500 ppm, confirming high safety.

一方、比較例1は、樹脂粒子全体の重量平均分子量が本発明の範囲以下(30.2万)であり、且つ表層部の分子量低下率が本発明の範囲以下(0.3%)であり、得られたスライス品は耐熱性が低く、融けしろが大きくなり、歩留まりが悪くなった。またニクロムカット面の亀甲高さが72μmとなり、凹凸がやや見られ表面の平滑がやや劣っていた。
また比較例2は、樹脂粒子全体の重量平均分子量が本発明の範囲以下(30.0万)であり、得られたスライス品は耐熱性が低く、融けしろが大きくなり、歩留まりが悪くなった。
また比較例3は、粒子全体の重量平均分子量よりも表層部の重量平均分子量の方が高く(低下率−3.9%)なり、得られたスライス品は、ニクロムカット面の亀甲高さが147μmと大きくなり、カット面は凹凸が明瞭に見られ、表面の平滑がかなり劣っていた。
また比較例4は、表層部の分子量低下率が本発明の範囲以上(7.0%)であり、得られたスライス品は、ニクロムカット面の亀甲高さがやや大きく(59μm)、カット面の平滑性がやや劣っており、且つ発泡粒子同士の融着性が悪く、曲げ強度などの機械強度が劣っていた。
On the other hand, in Comparative Example 1, the weight average molecular weight of the entire resin particles is below the range of the present invention (302,000), and the molecular weight reduction rate of the surface layer portion is below the range of the present invention (0.3%). The sliced product obtained had low heat resistance, increased melting margin, and yield decreased. Further, the turtle shell height of the Nichrome cut surface was 72 μm, and unevenness was slightly seen, and the smoothness of the surface was slightly inferior.
In Comparative Example 2, the weight average molecular weight of the entire resin particles was below the range of the present invention (30 million), and the obtained sliced product had low heat resistance, increased melting margin, and yield decreased. .
Further, in Comparative Example 3, the weight average molecular weight of the surface layer portion is higher than the weight average molecular weight of the whole particle (decrease rate -3.9%), and the obtained sliced product has a turtle shell height of the nichrome cut surface. Unevenness was clearly seen on the cut surface, and the smoothness of the surface was considerably inferior.
Further, in Comparative Example 4, the molecular weight reduction rate of the surface layer portion is not less than the range of the present invention (7.0%), and the obtained sliced product has a slightly large turtle shell height of the nichrome cut surface (59 μm), and the cut surface. The smoothness was slightly inferior, the fusibility between the expanded particles was poor, and the mechanical strength such as bending strength was inferior.

実施例において、予備発泡粒子の表層部をサンプリングする手法を示す平面図である。In an Example, it is a top view which shows the method of sampling the surface layer part of a pre-expanded particle. 実施例において、スライス品の亀甲高さの測定方法を説明するための拡大図である。In an Example, it is an enlarged view for demonstrating the measuring method of the turtle shell height of a sliced product.

Claims (10)

易揮発性発泡剤を含有する発泡性ポリスチレン系樹脂粒子であって、
ポリスチレン系樹脂粒子全体の重量平均分子量が33万〜50万の範囲にあり、かつポリスチレン系樹脂粒子表層部の重量平均分子量を(X)とし、粒子全体の重量平均分子量を(Y)とした時、次式(1)で求められる分子量低下率(%):
分子量低下率(%)=(Y−X)/Y×100 ・・・(1)
が0.5%〜5%の範囲内であることを特徴とする発泡性ポリスチレン系樹脂粒子。
Expandable polystyrene resin particles containing a readily volatile foaming agent,
When the weight average molecular weight of the entire polystyrene resin particle is in the range of 330,000 to 500,000, the weight average molecular weight of the surface layer of the polystyrene resin particle is (X), and the weight average molecular weight of the entire particle is (Y) The molecular weight reduction rate (%) obtained by the following formula (1):
Molecular weight reduction rate (%) = (Y−X) / Y × 100 (1)
Expandable polystyrene resin particles, characterized in that the content is in the range of 0.5% to 5%.
スチレン系単量体、エチルベンゼン、イソプロピルベンゼン、ノルマルプロピルベンゼン、キシレン、トルエンからなる芳香族有機化合物の含有量の総和が2000ppm未満であることを特徴とする請求項1に記載の発泡性ポリスチレン系樹脂粒子。   2. The expandable polystyrene resin according to claim 1, wherein the total content of aromatic organic compounds comprising a styrene monomer, ethylbenzene, isopropylbenzene, normal propylbenzene, xylene, and toluene is less than 2000 ppm. particle. 難燃剤を含有していることを特徴とする請求項1又は2に記載の発泡性ポリスチレン系樹脂粒子。   The expandable polystyrene resin particles according to claim 1 or 2, which contain a flame retardant. 架橋剤を含有していることを特徴とする請求項1〜3のいずれかに記載の発泡性ポリスチレン系樹脂粒子。   The expandable polystyrene resin particles according to any one of claims 1 to 3, further comprising a crosslinking agent. 請求項1〜4のいずれかに記載の発泡性ポリスチレン系樹脂粒子を加熱し予備発泡させて得られたポリスチレン系樹脂発泡粒子であって、
粒子全体の重量平均分子量が33万〜50万の範囲にあり、かつ発泡粒子表層部の重量平均分子量を(X)とし、発泡粒子全体の重量平均分子量を(Y)とした時、次式(1)で求められる分子量低下率(%):
分子量低下率(%)=(Y−X)/Y×100 ・・・(1)
が0.5%〜5%の範囲内であることを特徴とするポリスチレン系樹脂発泡粒子。
A polystyrene-based resin expanded particle obtained by heating and pre-expanding the expandable polystyrene-based resin particle according to claim 1,
When the weight average molecular weight of the entire particle is in the range of 330,000 to 500,000, the weight average molecular weight of the surface portion of the expanded particle is (X), and the weight average molecular weight of the entire expanded particle is (Y), the following formula ( Molecular weight reduction rate obtained in 1) (%):
Molecular weight reduction rate (%) = (Y−X) / Y × 100 (1)
Is within the range of 0.5% to 5%.
請求項5に記載のポリスチレン系樹脂発泡粒子を型内発泡成形して得られたポリスチレン系樹脂発泡成形体。   A polystyrene resin foam molded article obtained by in-mold foam molding of the polystyrene resin foam particles according to claim 5. 請求項6に記載のポリスチレン系樹脂発泡成形体を電気抵抗加熱線で所望形状にカットして得られたポリスチレン系樹脂発泡体スライス品。   A polystyrene resin foam slice obtained by cutting the polystyrene resin foam molded article according to claim 6 into a desired shape with an electric resistance heating wire. カット面における亀甲高さが50μm以下である請求項7に記載のポリスチレン系樹脂発泡体スライス品。   The polystyrene-based resin foam sliced product according to claim 7, wherein the turtle shell height on the cut surface is 50 μm or less. カット面における融けしろの量が3%未満であることを特徴とする請求項7又は8に記載のポリスチレン系樹脂発泡体スライス品。   The polystyrene-based resin foam sliced product according to claim 7 or 8, wherein the amount of margin on the cut surface is less than 3%. 水性媒体と、ポリスチレン系樹脂核粒子と、スチレン系単量体と、重合開始剤とを反応容器内に入れて加熱反応させ、ポリスチレン系樹脂核粒子の表面に新たにポリスチレン系樹脂層を形成し、易揮発性発泡剤を含浸させて発泡性ポリスチレン系樹脂粒子を得る製造方法であって、
粒子全体の重量平均分子量が33万〜50万の範囲にあり、かつ発泡粒子表層部の重量平均分子量を(X)とし、発泡粒子全体の重量平均分子量を(Y)とした時、次式(1)で求められる分子量低下率(%):
分子量低下率(%)=(Y−X)/Y×100 ・・・(1)
が0.5%〜5%の範囲内である発泡性ポリスチレン系樹脂粒子を得ることを特徴とする発泡性ポリスチレン系樹脂粒子の製造方法。
An aqueous medium, a polystyrene resin core particle, a styrene monomer, and a polymerization initiator are placed in a reaction vessel and heated to react to form a new polystyrene resin layer on the surface of the polystyrene resin core particle. , A production method for obtaining expandable polystyrene resin particles by impregnating a readily volatile foaming agent,
When the weight average molecular weight of the entire particle is in the range of 330,000 to 500,000, the weight average molecular weight of the surface portion of the expanded particle is (X), and the weight average molecular weight of the entire expanded particle is (Y), the following formula ( Molecular weight reduction rate obtained in 1) (%):
Molecular weight reduction rate (%) = (Y−X) / Y × 100 (1)
To obtain expandable polystyrene resin particles having a content of 0.5% to 5%.
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