JP2002284917A - Expandable styrene-based resin particle - Google Patents
Expandable styrene-based resin particleInfo
- Publication number
- JP2002284917A JP2002284917A JP2001088275A JP2001088275A JP2002284917A JP 2002284917 A JP2002284917 A JP 2002284917A JP 2001088275 A JP2001088275 A JP 2001088275A JP 2001088275 A JP2001088275 A JP 2001088275A JP 2002284917 A JP2002284917 A JP 2002284917A
- Authority
- JP
- Japan
- Prior art keywords
- styrene
- resin particles
- particles
- polymerization
- foamed
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
Abstract
Description
【０００１】[0001]
【産業上の利用分野】本発明は、発泡性スチレン系樹脂
粒子、予備発泡粒子、発泡成形体、断熱材および発泡性
スチレン系樹脂粒子の製造方法に関する。さらに詳しく
は、低密度でありながら、断熱性、外観等に優れたスチ
レン系樹脂発泡成形体が得られる発泡性スチレン系樹脂
粒子、それから得られる予備発泡粒子、発泡成形体、断
熱材および食品用保温材ならびに発泡性スチレン系樹脂
粒子の製造方法に関するものである。本発明のスチレン
系樹脂発泡成形体は、断熱性が求められる建材用断熱材
および食品用保温材等の素材として特に好適である。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an expandable styrene resin particle, a pre-expanded particle, a foam molded article, a heat insulating material, and a method for producing an expandable styrene resin particle. More specifically, expandable styrene-based resin particles from which a styrene-based resin foamed molded article having a low density and excellent heat insulating properties and appearance are obtained, pre-expanded particles obtained therefrom, foamed molded articles, heat-insulating materials, and foodstuffs The present invention relates to a method for producing a heat insulating material and expandable styrene resin particles. The styrenic resin foam molded article of the present invention is particularly suitable as a raw material such as a heat insulating material for building materials and a heat insulating material for food, which requires heat insulating properties.
【０００２】[0002]
【従来の技術】従来のビーズ法によるスチレン系樹脂発
泡成形体は、揮発性発泡剤を１〜１５重量％含有させた
発泡性スチレン系樹脂粒子を、水蒸気等の加熱媒体によ
り軟化点以上に加熱し、独立気泡を有する粒子状の予備
発泡粒子を得た後に、この予備発泡粒子を小さな孔やス
リットを有する閉鎖型金型の中に充填し、水蒸気等で内
部をさらに加熱し、予備発泡粒子が膨張して粒子間の隙
間を埋めながら互いに融着させる、所謂型内成形によっ
て製造されている。2. Description of the Related Art A conventional styrene resin foam molded article obtained by a bead method is obtained by heating expandable styrene resin particles containing a volatile foaming agent in an amount of 1 to 15% by weight to a softening point or higher with a heating medium such as steam. Then, after obtaining particulate pre-expanded particles having closed cells, the pre-expanded particles are filled in a closed mold having small holes and slits, and the inside is further heated with steam or the like to obtain pre-expanded particles. Are expanded and fused together while filling gaps between particles, so-called in-mold molding.
【０００３】このビーズ法によるスチレン系樹脂発泡成
形体は、軽量性（低密度）、形状の自由性およびその独
立気泡による断熱性、耐水性などの諸特性を有すること
から、住宅用などの断熱用建材および魚箱等の食品用保
温材に多く用いられている。近年、このような断熱材
は、より断熱性に優れ、低密度（０．０２ｇ／ｃｍ3以
下）であること等が強く求められるようになってきた。[0003] The foamed styrenic resin molded article by the bead method has various properties such as lightness (low density), freedom of shape, and heat insulation and water resistance due to its closed cells. It is widely used for building materials for food and heat insulation for food such as fish boxes. In recent years, it has been strongly demanded that such a heat insulating material be more excellent in heat insulating properties and have a low density (0.02 g / cm 3 or less).
【０００４】しかしながら、これらの特性、すなわち断
熱性と低密度は互いに相反する関係にあり、一般に発泡
体密度が低くなると熱伝導率が高くなる、すなわち断熱
性が低下することが知られている。例えば、特許庁発行
の「発泡の周知、慣用技術集：５７（１９８２）−１３
３［３３４７］」第８９頁には、発泡倍数が３３倍であ
るポリスチレン粒子を用いたフォームは熱伝導率が約
０．０３ｋｃａｌ／ｍｈ℃であるが、５０倍のものでは
熱伝導率が約０．０３４〜０．０３５ｋｃａｌ／ｍｈ℃
まで上昇することが示されている。[0004] However, these properties, that is, the heat insulation property and the low density are in a mutually contradictory relationship, and it is generally known that as the density of the foam decreases, the thermal conductivity increases, that is, the heat insulation property decreases. For example, "A collection of well-known and commonly used techniques of foaming" published by the Japan Patent Office: 57 (1982) -13
3 [3347] ", p. 89, that a foam using polystyrene particles having an expansion ratio of 33 times has a thermal conductivity of about 0.03 kcal / mh ° C, while a foam using polystyrene particles having a expansion rate of 33 times has a thermal conductivity of about 0.034-0.035 kcal / mh ° C
It is shown to rise up.
【０００５】また、特開昭５６−５０９３５号公報で
は、ポリスチレン等の合成樹脂発泡体は、発泡倍数が２
０〜３０倍（密度０．０３３〜０．０５０ｇ／ｃｍ3）
であるときに熱伝導率が低くなり、発泡体密度が低くな
るに伴って熱伝導率が高くなることが示されている。ま
た、同公報には低密度樹脂発泡体の熱伝導率を低くする
目的で、特定の赤外波長の電磁波を吸収する化学構造を
有し、さらに３００°Ｋでの黒体放射に対して特定の吸
収率を有する添加物を発泡体に含有させることが示され
ている。しかしながら、この方法では添加物を用いるた
め、コストアップになるばかりでなく、発泡成形性に悪
影響を与えるものと考えられる。Japanese Patent Application Laid-Open No. 50935/1981 discloses that a synthetic resin foam such as polystyrene has a foaming multiple of 2 times.
0 to 30 times (density 0.033 to 0.050 g / cm 3 )
It is shown that the thermal conductivity decreases when the thermal conductivity is lower, and the thermal conductivity increases as the foam density decreases. In addition, the publication has a chemical structure that absorbs electromagnetic waves of a specific infrared wavelength for the purpose of lowering the thermal conductivity of the low-density resin foam, and further specifies a black body radiation at 300 ° K. It is disclosed that an additive having an absorption rate of? However, in this method, since an additive is used, not only the cost is increased, but also it is considered that the foam moldability is adversely affected.
【０００６】発泡成形体を低密度にするためには、低密
度の予備発泡粒子を得ることが必要であるが、その目的
で予備発泡粒子をもう一度加熱発泡（多段発泡）させ
る、あるいは高温用予備発泡機を利用する方法等が従来
から知られている。しかしながら、通常のスチレン系樹
脂粒子をこれらの方法で予備発泡粒子としても発泡余力
が小さく、型内で再加熱して成形した場合、成形直後の
段階で収縮、変形を起こすという問題がある。したがっ
て、この収縮、変形を回復させる目的で、いわゆる養生
と呼ばれる操作、すなわち約５０℃で半日程度、乾燥室
に保管する操作が行なわれている。しかしながら、収縮
があまりに大きくなったものは形状回復に長時間を要す
るばかりか、中には回復しないものも発生する。In order to reduce the density of the foamed molded article, it is necessary to obtain low-density pre-expanded particles. For this purpose, the pre-expanded particles are heated again (multi-stage expansion) or pre-expanded for high temperature. A method using a foaming machine and the like have been conventionally known. However, even when ordinary styrene-based resin particles are used as pre-expanded particles by these methods, there is a small expansion capacity, and when they are reheated and molded in a mold, there is a problem that shrinkage and deformation occur immediately after molding. Therefore, for the purpose of recovering the shrinkage and deformation, an operation called curing is performed, that is, an operation of storing in a drying room at about 50 ° C. for about half a day is performed. However, if the shrinkage becomes too large, not only does it take a long time to recover the shape, but some of them do not recover.
【０００７】そこで、スチレン系発泡性樹脂粒子の発泡
性を改良する手段として、特公昭５８−４８５７８号公
報には、基材樹脂として汎用のポリスチレンに代えて、
スチレンにアクリル系樹脂を溶解し、重合して得られた
樹脂を用いることが記載されている。しかしながら、こ
の方法による場合、特殊なアクリル系樹脂を用いなけれ
ばならず、コストアップの原因となる。また、特公昭５
８−５８３７４号公報には、基材樹脂として汎用のポリ
スチレンに代えて、スチレンにアクリル酸エステルもし
くはメタクリル酸エステルを共重合させた樹脂を用いる
ことが記載されている。しかしながら、この方法では樹
脂のガラス転移温度が低下するので耐熱性の低下を招
き、成形時に成形品が融けてその外観が著しく悪くなっ
たり、成形品の機械的強度が劣ったりする問題があっ
た。Therefore, as a means for improving the expandability of the styrene-based expandable resin particles, Japanese Patent Publication No. 58-48578 discloses, instead of general-purpose polystyrene as a base resin,
It describes that a resin obtained by dissolving an acrylic resin in styrene and polymerizing is used. However, according to this method, a special acrylic resin must be used, which causes an increase in cost. In addition, Tokubo Sho 5
Japanese Patent Application Laid-Open No. 8-58374 describes that a resin obtained by copolymerizing styrene with an acrylate or methacrylate is used as a base resin instead of general-purpose polystyrene. However, in this method, the glass transition temperature of the resin is lowered, so that the heat resistance is lowered, and the molded product is melted at the time of molding and the appearance thereof is remarkably deteriorated, or the mechanical strength of the molded product is deteriorated. .
【０００８】また、特開平６−１００７２３号公報に
は、重量平均分子量（Ｍｗ）が１５〜２５万のポリスチ
レンに発泡剤としてイソブタンを含有させ、かつステア
リン酸トリグリセリド等のグリセリン脂肪酸エステルを
含有させることが記載されており、特開平１０−１５６
１号公報には、分子量が３０万〜４０万のポリスチレン
にステアリン酸トリグリセリド等の高級脂肪酸多価エス
テルに、ブタンおよびペンタンを含有させることが記載
されている。しかしながら、前者は樹脂を低分子量化す
ることで高発泡を可能としているが、成形品の強度低下
を避けることはできず、また、後者は比較的高分子量化
（３０万以上）にすることよって強度低下を抑制してい
るが、これによる発泡性の低下や成形品の融着性の低下
を補うため、ブタンに対するペンタンの使用割合が高
く、その結果として成形品の圧縮強度が低下する問題が
ある。JP-A-6-100723 discloses that polystyrene having a weight-average molecular weight (Mw) of 150,000 to 250,000 contains isobutane as a foaming agent and contains glycerin fatty acid esters such as stearic acid triglyceride. And JP-A-10-156.
No. 1 describes that polystyrene having a molecular weight of 300,000 to 400,000 is made to contain butane and pentane in a higher fatty acid polyvalent ester such as stearic acid triglyceride. However, although the former enables high foaming by reducing the molecular weight of the resin, it cannot avoid a decrease in the strength of the molded product, and the latter requires a relatively high molecular weight (300,000 or more). Although the decrease in strength is suppressed, the use ratio of pentane to butane is high to compensate for the decrease in foaming property and the decrease in fusibility of the molded product, resulting in a problem that the compression strength of the molded product is reduced. is there.
【０００９】また、発泡性樹脂粒子の発泡性を改良する
ために、樹脂粒子に、発泡剤以外の溶剤、可塑剤等を含
有させる方法も行われている。しかしながら、溶剤、可
塑剤等の含有量を多くすると、発泡性は向上するが、樹
脂の耐熱性が低下し、成形時の加熱等によって融けが発
生し、成形品の外観が悪くなったり、気泡が破れやすく
なったりして断熱性が低下するという問題があった。In order to improve the expandability of the expandable resin particles, a method of incorporating a solvent other than a foaming agent, a plasticizer, and the like into the resin particles has also been performed. However, when the content of the solvent, the plasticizer, etc. is increased, the foaming property is improved, but the heat resistance of the resin is reduced, and the resin is melted by heating at the time of molding, etc. However, there has been a problem that the heat insulating property is deteriorated due to the breakage of the material.
【００１０】さらに、最近の断熱材に求められる品質と
しては、シックハウス症候群、化学物質過敏症の原因と
考えられている室内空気汚染物質、すなわち、従来の発
泡性スチレン系樹脂粒子の製造に、溶剤、可塑剤として
使用されてきたシクロヘキサン、スチレン、トルエン、
エチルベンゼン、キシレン、ＤＯＰなどの添加量が少な
いもの、できれば添加されていないものが好まれる傾向
にある。しかしながら、これらの物質は発泡性樹脂粒子
の低密度化に必要であり、上記の要求と低密度化を同時
に満足することは困難であった。[0010] Furthermore, the quality required of recent heat insulating materials is sick house syndrome, indoor air pollutants which are considered to be a cause of chemical sensitivity, that is, the conventional method of producing expandable styrene resin particles requires solvent. , Cyclohexane, styrene, toluene, which has been used as a plasticizer,
Ethylenebenzene, xylene, DOP and the like with a small addition amount, and preferably without addition, tend to be preferred. However, these substances are necessary for reducing the density of the expandable resin particles, and it has been difficult to simultaneously satisfy the above requirements and the reduction in density.
【００１１】[0011]
【発明が解決しようとする課題】本発明は、発泡成形体
の低密度化に伴う断熱性低下の問題を解決するものであ
る。熱可塑性樹脂発泡成形体の断熱性については、以前
から検討され、熱伝導率に与える発泡体の因子として、
樹脂量（発泡体密度）、気泡内のガス種、気泡径等が挙
げられている。SUMMARY OF THE INVENTION The present invention is intended to solve the problem of a decrease in heat insulation due to a decrease in the density of a foam molded article. The thermal insulation properties of thermoplastic resin foam moldings have been studied for a long time, and as a factor of the foam giving thermal conductivity,
The amount of resin (foam density), the gas type in the cells, the cell diameter, and the like are listed.
【００１２】本発明のような低密度領域においては樹脂
相における熱伝導の影響は非常に小さい。また、気泡内
のガス種としてはフロン系ガスが有効であることが知ら
れているが、スチレン系樹脂のようなガスバリヤー性に
乏しい樹脂では、経時によってガスが発泡体から逸散
し、空気と置換されて発泡体の断熱性が低くなることが
知られている。また、フロン系ガスは、オゾン層を破壊
するという点で好ましくない。発泡体の気泡径は、断熱
性と関係が深く、輻射熱を遮断するために気泡径を小さ
くすること、すなわち気泡膜による輻射熱の遮断回数を
増やすことが有効であることが知られている。In the low-density region as in the present invention, the effect of heat conduction in the resin phase is very small. It is known that a fluorocarbon-based gas is effective as a gas species in bubbles.However, in a resin having a poor gas barrier property such as a styrene-based resin, the gas escapes from the foam over time and air It is known that the thermal insulation of the foam is reduced by the substitution. Further, chlorofluorocarbon-based gas is not preferable in that it destroys the ozone layer. It is known that the cell diameter of the foam is closely related to the heat insulating property, and that it is effective to reduce the cell diameter in order to cut off radiant heat, that is, to increase the number of cutoffs of radiant heat by the cell membrane.
【００１３】しかしながら、本発明者が詳細に検討した
ところ、低密度領域においては気泡径を小さくしても熱
伝導率は改善されず、予想に反して熱伝導率は高くなる
ことが分かった。そこで、本発明者は気泡を形成する気
泡膜厚に着目し、研究を進めた結果、予備発泡粒子の嵩
密度および発泡成形体の密度が０．０２〜０．００９ｇ
／ｃｍ3において、平均気泡膜厚が０．８〜２．５μｍ
であると、最も優れた断熱性が示されることを見出し
た。However, the present inventor has studied in detail that it has been found that the thermal conductivity is not improved even in the low-density region even if the bubble diameter is reduced, and the thermal conductivity is unexpectedly increased. Therefore, the present inventor paid attention to the cell film thickness forming the cells, and as a result of studying, the bulk density of the pre-expanded particles and the density of the expanded molded article were 0.02 to 0.009 g.
/ Cm 3 , the average bubble film thickness is 0.8 to 2.5 μm
Was found to show the most excellent heat insulating properties.
【００１４】また、従来から気泡膜の状態と断熱性の関
係について、連続気泡率という指標が用いられ、この連
続気泡率が高い、すなわち気泡膜の破れが多い発泡体は
輻射熱の遮断回数の減少から断熱性が低く、強度にも劣
ることが知られていた。しかしながら、本発明者の研究
の結果、連続気泡率は低くても、断熱性が劣る場合があ
り、これについて考察したところ、連続気泡率が低くて
も気泡膜に皺の発生が多い発泡体は断熱性能が低下して
いることが判明した。Conventionally, an index called an open cell ratio has been used for the relationship between the state of the bubble film and the heat insulating property. A foam having a high open cell ratio, that is, a foam having many breaks in the bubble film, has a reduced number of cutoffs of radiant heat. Therefore, it was known that heat insulation was low and strength was poor. However, as a result of the study of the present inventor, even if the open cell ratio is low, the heat insulating property may be inferior. It was found that the heat insulation performance was reduced.
【００１５】すなわち、発泡体の気泡膜の状態を観察す
ることによって、低密度の発泡成形体では気泡膜の状態
が断熱性能に大きく影響すること、また断熱性に優れた
発泡成形体を得るには気泡膜の表面が平滑で張りあるも
のでなければならないことが分かった。気泡膜に皺が発
生する原因としては、充分な発泡性を有しない発泡性ス
チレン系樹脂粒子を高温発泡等で低密度化させること、
あるいは物理的衝撃によること等が考えられる。したが
って、優れた断熱性を有する発泡成形体を得るには、低
密度化に適したスチレン系樹脂を用いる必要がある。That is, by observing the state of the foam film of the foam, it is found that the state of the foam film has a great influence on the heat insulating performance in a low-density foam molded article, and that a foam molded article having excellent heat insulating properties can be obtained. It was found that the surface of the bubble film had to be smooth and taut. The cause of wrinkles in the foam film is to reduce the density of expandable styrene resin particles that do not have sufficient foaming properties by high-temperature foaming or the like,
Alternatively, it may be due to a physical impact. Therefore, in order to obtain a foamed molded article having excellent heat insulating properties, it is necessary to use a styrene-based resin suitable for reducing the density.
【００１６】[0016]
【課題を解決するための手段】そこで、本発明者はスチ
レン系樹脂を低密度化に適したものとするために、基材
となるスチレン系樹脂の特性についても研究を行った。
その結果、重量平均分子量Ｍｗが３０万〜６０万であっ
て、かつメルトフローレート測定時、オリフィスの内径
をＢｍｍ、樹脂ストランドの外径をＡｍｍとしたときの
膨張割合ＳＲ（Ａ／Ｂ）が１．５〜３．０の範囲内に調
整されたスチレン系樹脂は、少ない発泡剤、溶剤、可塑
剤量で充分な発泡性が得られ、断熱材用発泡成形体を得
るのに最適であることを見出した。In order to make the styrenic resin suitable for lowering the density, the present inventor has also studied the characteristics of the styrenic resin as the base material.
As a result, when the weight average molecular weight Mw is 300,000 to 600,000, and the melt flow rate is measured, the expansion ratio SR (A / B) when the inner diameter of the orifice is Bmm and the outer diameter of the resin strand is Amm, The styrene-based resin adjusted within the range of 1.5 to 3.0 provides sufficient foaming properties with a small amount of a foaming agent, a solvent, and a plasticizer, and is most suitable for obtaining a foamed molded article for a heat insulating material. I found that.
【００１７】かくして、本発明によれば、重量平均分子
量Ｍｗが３０万〜６０万であり、かつメルトフロー測定
時、オリフィスの内径をＢｍｍ、樹脂ストランドの外径
をＡｍｍとしたときの膨張割合ＳＲ（Ａ／Ｂ）が１．５
〜３．０であるスチレン系樹脂粒子に発泡剤を含有させ
てなり、嵩密度０．０２〜０．００９ｇ／ｃｍ3に発泡
させたときの平均気泡膜厚が０．８〜２．５μｍである
ことを特徴とする発泡性スチレン系樹脂粒子が提供され
る。Thus, according to the present invention, the expansion ratio SR when the weight average molecular weight Mw is 300,000 to 600,000 and the inner diameter of the orifice is Bmm and the outer diameter of the resin strand is Amm at the time of melt flow measurement. (A / B) is 1.5
Styrene-based resin particles having an average cell thickness of 0.8 to 2.5 μm when foamed to a bulk density of 0.02 to 0.009 g / cm 3. An expandable styrene-based resin particle is provided.
【００１８】また、本発明によれば、上記の発泡性スチ
レン系樹脂粒子を加熱して予備発泡させてなり、嵩密度
が０．０２〜０．００９ｇ／ｃｍ3 、平均気泡膜厚が
０．８〜２．５μｍである予備発泡粒子が提供される。
また、本発明によれば、上記の予備発泡粒子を加熱し、
発泡成形してなるスチレン系樹脂発泡成形体が提供され
る。According to the present invention, the expandable styrenic resin particles are pre-foamed by heating, and have a bulk density of 0.02 to 0.009 g / cm 3 and an average cell thickness of 0.1 to 0.09 g / cm 3 . Pre-expanded particles that are between 8 and 2.5 μm are provided.
Also, according to the present invention, heating the pre-expanded particles,
A styrene resin foam molded article obtained by foam molding is provided.
【００１９】また、本発明によれば、上記のスチレン系
樹脂発泡成形体からなる建築用断熱材および食品用保温
材が提供される。Further, according to the present invention, there are provided a heat insulating material for building and a heat insulating material for food, comprising the above-mentioned styrene resin foam molded article.
【００２０】また、本発明によれば、水性媒体中にスチ
レン系樹脂粒子が分散した懸濁液にスチレン系単量体を
添加してシード重合する際において、重合過程において
推移する重合転化率の最低値が８５〜９４重量％となる
ように制御しながらシード重合してスチレン系樹脂粒子
を製造し、該スチレン系樹脂粒子に発泡剤を含有させる
ことを特徴とする発泡性スチレン系樹脂粒子の製造方法
が提供される。Further, according to the present invention, when a styrene-based monomer is added to a suspension in which styrene-based resin particles are dispersed in an aqueous medium and seed polymerization is performed, the polymerization conversion rate that changes during the polymerization process is obtained. Producing styrene-based resin particles by performing seed polymerization while controlling the minimum value to be 85 to 94% by weight; and adding a foaming agent to the styrene-based resin particles. A manufacturing method is provided.
【００２１】[0021]
【本発明の実施の形態】本発明で用いられるスチレン系
樹脂粒子は、スチレン系単量体を水中に懸濁させて重合
させる、いわゆる懸濁重合法、または水性媒体中にスチ
レン系樹脂粒子（種粒子）を分散させ、これにスチレン
系単量体を連続的または断続的に供給して懸濁重合させ
る、いわゆるシード重合法により製造できる。発泡成形
体に所望の平均気泡膜厚をもたせるためには、シード重
合法により製造するのが好ましい。DETAILED DESCRIPTION OF THE INVENTION The styrene resin particles used in the present invention are prepared by suspending a styrene monomer in water and polymerizing the suspension. The seed particles are dispersed, and a styrene-based monomer is continuously or intermittently supplied thereto to perform suspension polymerization, which is a so-called seed polymerization method. In order to give the foamed molded article a desired average cell thickness, it is preferable to produce the foamed molded article by a seed polymerization method.
【００２２】上記のようにして得られたスチレン系樹脂
粒子は、押出機にてペレット化することで所望の粒度に
調整することができる。シード重合法で使用する種粒子
としては、ポリスチレンを主成分とし、具体的にはスチ
レン単独重合体を５０重量％以上、好ましくは８０重量
％以上含み、スチレンと他の共重合可能な少量のコモノ
マーとの共重合体を含むものが挙げられる。The styrene resin particles obtained as described above can be adjusted to a desired particle size by pelletizing with an extruder. The seed particles used in the seed polymerization method include polystyrene as a main component, specifically, 50% by weight or more, preferably 80% by weight or more of a styrene homopolymer, and a small amount of a copolymerizable monomer with styrene. And a copolymer containing a copolymer of
【００２３】種粒子の使用割合は、重合終了時の重合体
全量に対して、通常、１０〜６０重量％程度、好ましく
は１５〜５０重量％である。種粒子の使用量が１０重量
％を下回ると、スチレン系単量体を供給する際に、重合
体粒子の重合転化率を適正範囲に制御することが難し
く、得られた重合体粒子が高分子化したり、微粉末状重
合体を発生させて製造効率を低下させたりする等、工業
的に好ましくない。また、種粒子の使用量が６０重量％
を上回ると、発泡性、断熱性に優れた発泡成形体が得ら
れ難くなり好ましくない。The use ratio of the seed particles is usually about 10 to 60% by weight, preferably 15 to 50% by weight, based on the total amount of the polymer at the end of the polymerization. If the use amount of the seed particles is less than 10% by weight, it is difficult to control the polymerization conversion of the polymer particles in an appropriate range when supplying the styrene monomer, and the obtained polymer particles are Or the production efficiency is reduced by generating a fine powdery polymer, which is not industrially preferable. The amount of seed particles used is 60% by weight.
If the ratio exceeds the above, it is difficult to obtain a foam molded article having excellent foaming properties and heat insulating properties, which is not preferable.
【００２４】スチレンと他の共重合可能な少量のコモノ
マーとしては、例えば、α−メチルスチレン、アクリロ
ニトリル、メチルメタクリレート等や、多官能性モノマ
ーが挙げられる。なかでも、発泡成形体の気泡に破れや
皺の生成を抑制し、より低い熱伝導率を得るためには、
多官能性モノマーの使用が好ましい。多官能性モノマー
としては、特に限定されず、一般に使用されるジビニル
ベンゼンや、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。特に、ジビニルベンゼンは低コストであ
るため好ましい。なお、ジビニルベンゼンは、ｏ−、ｍ
−またはｐ−ジビニルベンゼンのいずれでもよく、また
それらの混合物でもよい。[0024] Examples of small amounts of copolymerizable comonomers with styrene include α-methylstyrene, acrylonitrile, methyl methacrylate and the like, and polyfunctional monomers. Above all, in order to suppress the generation of tears and wrinkles in the cells of the foam molded article, and to obtain a lower thermal conductivity,
The use of polyfunctional monomers is preferred. The polyfunctional monomer is not particularly limited, and includes generally used divinylbenzene, alkylene glycol dimethacrylate, and the like. In particular, divinylbenzene is preferable because of its low cost. In addition, divinylbenzene is o-, m
-Or p-divinylbenzene, or a mixture thereof.
【００２５】多官能性モノマーの使用量は、スチレン系
単量体に対して、通常、０．０１〜０．０２５ｍｏｌ％
程度であり、０．０１５〜０．０２５ｍｏｌ％が好まし
い。シード重合では、重合開始剤を用いてもよい。重合
開始剤としては、スチレンの懸濁重合で通常用いられて
いるラジカル発生型重合開始剤、例えばベンゾイルパー
オキサイド、ラウリルパーオキサイド、ｔ−ブチルパー
オキサイド、ｔ−ブチルパーオキシピバレート、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、２，２−ｔ−ブチルパーオキシ
ブタン、ｔ−ブチルパーオキシ−３，３，５−トリメチ
ルヘキサノエート、ジ−ｔ−ブチルパーオキシヘキサハ
イドロテレフタレート等の有機過酸化物や、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
のアゾ化合物などが挙げられる。The amount of the polyfunctional monomer is usually 0.01 to 0.025 mol% based on the styrene monomer.
And it is preferably 0.015 to 0.025 mol%. In the seed polymerization, a polymerization initiator may be used. As the polymerization initiator, a radical generation type polymerization initiator usually used in suspension polymerization of styrene, for example, benzoyl peroxide, lauryl peroxide, t-butyl peroxide, t-butylperoxypivalate, t-butyl Peroxyisopropyl carbonate, t-butylperoxyacetate, 2,2-t-butylperoxybutane, t-butylperoxy-3,3,5-trimethylhexanoate, di-t-butylperoxyhexahydroterephthalate And azo compounds such as azobisisobutyronitrile and azobisdimethylvaleronitrile.
【００２６】これらの重合開始剤は、単独で、または２
種以上を組合わせて用いることができる。樹脂粒子の分
子量を調整し、残留単量体の量を減少させるためには、
１０時間の半減期を得るための分解温度が８０〜１２０
℃の範囲にある重合開始剤、例えばｔ−ブチルパーオキ
シベンゾエート、ｔ−ブチルパーオキシピバレート、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、２，２−ｔ−ブチルパーオ
キシブタンなどを２種以上組み合わせて用いるのが好ま
しい。These polymerization initiators can be used alone or
More than one species can be used in combination. In order to adjust the molecular weight of the resin particles and reduce the amount of residual monomer,
The decomposition temperature for obtaining a half-life of 10 hours is 80 to 120.
Polymerization initiators in the range of ° C, such as t-butyl peroxybenzoate, t-butyl peroxypivalate, t
It is preferable to use two or more kinds of -butyl peroxyisopropyl carbonate, t-butyl peroxy acetate, 2,2-t-butyl peroxybutane and the like.
【００２７】シード重合を行う際に、スチレン系単量体
の小滴および種粒子を水性媒体中に分散させるために、
懸濁剤を用いてもよい。懸濁剤としては、従来から懸濁
重合で一般に用いられるポリビニルアルコール、メチル
セルロース、ポリアクリルアミド、ポリビニルピロリド
ン等の水溶性高分子や、第三リン酸カルシウム、ピロリ
ン酸マグネシウム等の難水溶性無機化合物等が挙げられ
る。なお、難水溶性無機化合物を用いる場合には、アニ
オン界面活性剤を併用するのが好ましい。In performing the seed polymerization, in order to disperse the droplets and seed particles of the styrenic monomer in an aqueous medium,
Suspensions may be used. Examples of the suspending agent include water-soluble polymers such as polyvinyl alcohol, methyl cellulose, polyacrylamide, and polyvinylpyrrolidone, which are generally used in suspension polymerization, and poorly water-soluble inorganic compounds such as tricalcium phosphate and magnesium pyrophosphate. Can be When a poorly water-soluble inorganic compound is used, it is preferable to use an anionic surfactant in combination.
【００２８】アニオン界面活性剤としては、例えば脂肪
酸石鹸、Ｎ−アシルアミノ酸またはその塩、アルキルエ
ーテルカルボン酸塩などのカルボン酸塩、アルキルベン
ゼンスルホン酸塩、アルキルナフタレンスルホン酸塩、
ジアルキルスルホコハク酸エステル塩、アルキルスルホ
酢酸塩、α−オレフィンスルホン酸塩などのスルホン酸
塩；高級アルコール硫酸エステル塩、第二級高級アルコ
ール硫酸エステル塩、アルキルエーテル硫酸塩、ポリオ
キシエチレンアルキルフェニルエーテル硫酸塩などの硫
酸エステル塩；アルキルエーテルリン酸エステル塩、ア
ルキルリン酸エステル塩等のリン酸エステル塩などが挙
げられる。Examples of the anionic surfactant include fatty acid soaps, N-acyl amino acids or salts thereof, carboxylate salts such as alkyl ether carboxylate, alkylbenzene sulfonate, alkylnaphthalene sulfonate, and the like.
Sulfonates such as dialkylsulfosuccinates, alkylsulfoacetates and α-olefin sulfonates; higher alcohol sulfates, secondary higher alcohol sulfates, alkyl ether sulfates, polyoxyethylene alkylphenyl ether sulfates Sulfuric acid ester salts such as salts; phosphoric acid ester salts such as alkyl ether phosphoric acid ester salts and alkyl phosphoric acid ester salts;
【００２９】シード重合を行うにあたって、重合温度プ
ログラム、重合開始剤の配分、スチレン系単量体の供給
速度、重合時の重合転化率等を適宜調整することによ
り、スチレン系樹脂粒子の重合過程において推移するス
チレン系樹脂粒子の重合転化率の最低値（最低重合転化
率）を８５〜９４％、より好ましくは８８〜９３％に制
御することができる。なお、本発明における重合転化率
は、以下の式で示される。重合転化率（重量％）＝（Ａ
−Ｂ）×１００／Ａただし、Ａは、分散媒から分離し水
分を除いた未反応の単量体を含んだスチレン系樹脂粒子
の重量（ｇ）であり、Ｂは、上記未反応単量体を含む樹
脂粒子中の未反応単量体の重量（ｇ）である。Ａおよび
Ｂは、例えば、ガスクロマトグラフ等で定量される。In performing the seed polymerization, the polymerization temperature program, the distribution of the polymerization initiator, the supply rate of the styrene-based monomer, the polymerization conversion during the polymerization, and the like are appropriately adjusted so that the polymerization of the styrene-based resin particles can be performed. The lowest value (minimum polymerization conversion) of the changing polymerization conversion rate of the styrene-based resin particles can be controlled to 85 to 94%, more preferably 88 to 93%. The polymerization conversion in the present invention is represented by the following equation. Polymerization conversion (% by weight) = (A
-B) × 100 / A where A is the weight (g) of styrene resin particles containing unreacted monomers separated from the dispersion medium and excluding water, and B is the unreacted monomer It is the weight (g) of the unreacted monomer in the resin particles containing the body. A and B are quantified by, for example, a gas chromatograph.
【００３０】最低重合転化率が８５％を下回ると、スチ
レン系樹脂粒子に分散剤等が混入し、気泡膜厚を調整す
る上で好ましくないばかりか、微細粉末が多くなり生産
性が低下するので好ましくない。また、最低重合転化率
が９４％を上回ると、得られる発泡成形体の気泡が粗大
なものとなり、断熱性および機械的強度などの物性が低
下するので好ましくない。If the minimum polymerization conversion is less than 85%, a dispersant or the like is mixed into the styrene resin particles, which is not only unfavorable in adjusting the bubble film thickness, but also increases the fine powder and lowers the productivity. Not preferred. On the other hand, if the minimum polymerization conversion rate is more than 94%, the foams of the obtained foamed molded article become coarse, and physical properties such as heat insulation and mechanical strength are undesirably reduced.
【００３１】シード重合法では、後に得られる発泡成形
体の平均気泡膜厚を所望の範囲に調整するために、重合
終了５〜１０分前、または重合終了直後に、気泡調整剤
を添加するのが好ましい。気泡調整剤としては、例えば
エチレンビスステアリン酸アマイド等のステアリン酸塩
や、トリグリセリン脂肪酸エステル等が挙げられる。気
泡調整剤の添加割合は、スチレン系樹脂粒子に対して、
通常０．０１〜０．８重量％程度である。In the seed polymerization method, in order to adjust the average cell thickness of the foamed article obtained later to a desired range, a cell regulator is added 5 to 10 minutes before or immediately after the completion of the polymerization. Is preferred. Examples of the cell regulator include stearate salts such as ethylene bisstearic acid amide, and triglycerin fatty acid esters. The addition ratio of the foam adjuster is based on the styrene resin particles.
Usually, it is about 0.01 to 0.8% by weight.
【００３２】シード重合法で得られたスチレン系樹脂粒
子は、所望の粒子径に適宜調整することができる。スチ
レン系樹脂粒子の粒子径は、特に限定されないが、成形
時の金型への充填性等の点で、通常、０．３〜２．０ｍ
ｍ程度であり、好ましくは０．３〜１．４ｍｍ程度であ
る。スチレン系樹脂粒子の重量平均分子量は、ＧＰＣ法
によるスチレン換算重量平均分子量（Ｍｗ）で、３０万
〜６０万である。重量平均分子量が３０万を下回ると成
形体の強度が低下し、６０万を上回ると充分な発泡性を
得ることができず、低密度化が難しい。The styrene resin particles obtained by the seed polymerization method can be appropriately adjusted to a desired particle diameter. The particle diameter of the styrene-based resin particles is not particularly limited, but is usually 0.3 to 2.0 m in terms of filling properties into a mold at the time of molding.
m, and preferably about 0.3 to 1.4 mm. The weight average molecular weight of the styrene resin particles is 300,000 to 600,000 in terms of styrene equivalent weight average molecular weight (Mw) by GPC method. When the weight average molecular weight is less than 300,000, the strength of the molded body is reduced. When the weight average molecular weight is more than 600,000, sufficient foamability cannot be obtained, and it is difficult to reduce the density.
【００３３】スチレン系樹脂粒子は、メルトフローレー
ト測定時、オリフィスの内径をＢｍｍ、樹脂ストランド
の外径をＡｍｍとしたときの膨張割合ＳＲ（Ａ／Ｂ）が
１．５〜３．０である。膨張割合ＳＲが１．５を下回る
と、発泡性が不十分であり、低密度化によって発泡成形
体に収縮が起こり易く、外観が劣ったものとなる。この
場合、発泡成形体を養成しても、収縮の回復性は低い。
また、膨張割合が３．０を上回ると、逆に発泡性が低く
なり、低密度の発泡成形体が得られない。When measuring the melt flow rate, the styrene resin particles have an expansion ratio SR (A / B) of 1.5 to 3.0 when the inner diameter of the orifice is B mm and the outer diameter of the resin strand is A mm. . If the expansion ratio SR is less than 1.5, the foaming properties are insufficient, and the foamed molded article tends to shrink due to the low density, resulting in poor appearance. In this case, even if the foamed molded body is trained, the recovery from shrinkage is low.
On the other hand, if the expansion ratio exceeds 3.0, the foaming property is conversely low, and a low-density foam molded article cannot be obtained.
【００３４】なお、膨張割合（ＳＲ）は次の条件で測定
した。 測定装置：東洋精機製作所製 商品名 メルトインデク
サー 測定温度：２００℃ 荷重重量：５ｋｇｆ オリフィス径：２．０９ｍｍ（Ｂ） 押出後のストランド径 ：Ａ ｍｍ（ストランド先端から
５ｍｍの間で任意の５箇所で測定） 膨張割合（ＳＲ ）＝ Ａ／Ｂ 測定方法：スチレン系樹脂粒子１〜３ｇをあらかじめ２
００℃に加熱したメルトインデクサー内に入れ、３分間
放置する。次に５ｋｇｆの荷重を加え、オリフィス（径
２．０９ｍｍ）からスチレン系樹脂を押し出す。次に、
押し出されたストランドを取り、先端から５ｍｍの間で
ストランド径を１ｍｍ間隔で５個所測定し、その平均値
をＡとする。ＡをＢで除することにより、膨張割合（Ｓ
Ｒ）が算出される。The expansion ratio (SR) was measured under the following conditions. Measuring device: Toyo Seiki Seisakusho Co., Ltd. Melt indexer Measurement temperature: 200 ° C Load weight: 5 kgf Orifice diameter: 2.09 mm (B) Strand diameter after extrusion: A mm (arbitrary 5 points between 5 mm from strand tip) Expansion ratio (SR) = A / B Measurement method: 1 to 3 g of styrene-based resin particles 2
Place in a melt indexer heated to 00 ° C. and leave for 3 minutes. Next, a load of 5 kgf is applied to extrude the styrene resin from the orifice (diameter 2.09 mm). next,
The extruded strand is taken, and the diameter of the strand is measured at 5 points at intervals of 1 mm between 5 mm from the tip, and the average value is set to A. By dividing A by B, the expansion ratio (S
R) is calculated.
【００３５】上記のようにして得られるスチレン系樹脂
粒子に、通常行われる懸濁重合含浸法または後含浸法に
よって発泡剤を含浸させることにより、発泡性スチレン
系樹脂粒子を製造できる。The expandable styrene resin particles can be produced by impregnating the styrene resin particles obtained as described above with a foaming agent by a conventional suspension polymerization impregnation method or post-impregnation method.
【００３６】本発明で用いられる発泡剤としては、一般
の熱可塑性樹脂発泡体の製造に用いられている脂肪族炭
化水素、すなわちプロパン、ブタン、イソブタン、ペン
タン等や、ＨＣＦＣ−１４１ｂ、ＨＣＦＣ−１４２ｂ、
ＨＣＦＣ−１２４、ＨＦＣ−１３４ａ、ＨＦＣ−１５２
ａ等のフロン系発泡剤が挙げられる。なかでも、ブタ
ン、イソブタン、ペンタン等の脂肪族炭化水素が好まし
い。これらの発泡剤はそれぞれ単独で、または２種以上
を組み合わせて用いることができる。Examples of the foaming agent used in the present invention include aliphatic hydrocarbons used in the production of general thermoplastic resin foams, that is, propane, butane, isobutane, pentane, etc., and HCFC-141b, HCFC-142b. ,
HCFC-124, HFC-134a, HFC-152
and a flon-based foaming agent such as a. Among them, aliphatic hydrocarbons such as butane, isobutane and pentane are preferred. These foaming agents can be used alone or in combination of two or more.
【００３７】発泡剤の含有割合は、スチレン系樹脂粒子
に対して、通常、２〜９重量％程度、好ましくは３〜７
重量％である。発泡剤の含有割合が２重量％を下回る
と、発泡成形体の低密度化が難しく、成形時の二次発泡
力を高める効果が得られ難いために、発泡成形体の外観
が劣るので好ましくない。また、発泡剤の含有割合が９
重量％を上回ると、予備発泡粒子の残存ガス調整時間
や、成形サイクルが長くなり易く、その上発泡成形後の
収縮が起こり易くなり好ましくない。The content of the foaming agent is usually about 2 to 9% by weight, preferably 3 to 7% by weight, based on the styrene resin particles.
% By weight. When the content ratio of the foaming agent is less than 2% by weight, it is difficult to reduce the density of the foamed molded article, and it is difficult to obtain the effect of increasing the secondary foaming force at the time of molding. . When the content of the foaming agent is 9
If the content is more than 10% by weight, the time for adjusting the residual gas of the pre-expanded particles and the molding cycle tend to be long, and furthermore, shrinkage after foam molding tends to occur, which is not preferable.
【００３８】スチレン系樹脂粒子には、発泡剤の他に、
一般の発泡性スチレン系樹脂粒子の製造に用いられてい
る溶剤または可塑剤を必要に応じて適宜添加することが
できる。そのような溶剤としては、例えば、スチレン、
トルエン、エチルベンゼン、キシレン等の芳香族有機化
合物や、シクロヘキサン、メチルシクロヘキサン等の環
式脂肪族炭化水素や、酢酸エチル、酢酸ブチル等が挙げ
られる。In the styrene resin particles, besides the foaming agent,
Solvents or plasticizers used in the production of general expandable styrene resin particles can be added as needed. Such solvents include, for example, styrene,
Examples thereof include aromatic organic compounds such as toluene, ethylbenzene, and xylene; cycloaliphatic hydrocarbons such as cyclohexane and methylcyclohexane; and ethyl acetate and butyl acetate.
【００３９】また、可塑剤としては、例えばフタル酸エ
ステル、グリセリンジアセトモノラウレート、グリセリ
ントリステアレート等のグリセリン脂肪酸エステルや、
ジアセチル化モノステアリン酸グリセリド、ジイソブチ
ルアジペート等のアジピン酸エステル等が挙げられる。
これらの溶剤および可塑剤の使用割合は、シックハウス
症候群等の問題からできるだけ少ない方が好ましいが、
それぞれ、スチレン系樹脂粒子に対して、通常、０．１
〜１．５重量％程度、好ましくは０．２〜１．０重量％
である。溶剤または可塑剤の使用割合が０．１重量％を
下回ると充分な可塑効果が得られず、可塑剤を使用する
メリットが少ないので好ましくない。また、溶剤または
可塑剤の使用割合が１．５重量％を上回ると発泡成形時
に収縮および溶けが発生しやすく、気泡膜の破れ、成形
体の外観不良、製造コストのアップ等、好ましくない状
況が発生しやすい。Examples of the plasticizer include glycerin fatty acid esters such as phthalic acid ester, glycerin diacetomonolaurate and glycerin tristearate;
Adipates such as diacetylated monostearic acid glyceride and diisobutyl adipate;
The use ratio of these solvents and plasticizers is preferably as small as possible from problems such as sick house syndrome,
Each is usually 0.1 to styrene resin particles.
About 1.5% by weight, preferably 0.2 to 1.0% by weight
It is. If the use ratio of the solvent or the plasticizer is less than 0.1% by weight, a sufficient plasticizing effect cannot be obtained and the merit of using the plasticizer is small, which is not preferable. On the other hand, if the use ratio of the solvent or the plasticizer exceeds 1.5% by weight, shrinkage and melting are apt to occur during foam molding, and unfavorable situations such as breakage of a bubble film, poor appearance of a molded article, and increased production cost are caused. Likely to happen.
【００４０】溶剤および可塑剤は、通常、スチレン系樹
脂粒子に発泡剤を含浸させるときに添加されるが、発泡
性ポリスチレン系樹脂粒子中に均一に含有させるため
に、スチレン系樹脂粒子の重合段階で添加してもよく、
スチレン系樹脂粒子を押出機等で造粒する際の溶融段階
で添加してもよい。発泡剤、溶剤および可塑剤をスチレ
ン系樹脂粒子に含有させるときの温度は、スチレン系樹
脂粒子の粒子径により適宜選択されるが、通常、６０〜
１２０℃程度、好ましくは７０〜１００℃である。６０
℃を下回ると処理時間が長くなり好ましくない。また、
１２０℃を上回ると、樹脂粒子同士の結合粒が多くなり
好ましくない。The solvent and the plasticizer are usually added when impregnating the styrenic resin particles with the foaming agent. May be added at
The styrene resin particles may be added at the melting stage when granulating with an extruder or the like. The temperature at which the blowing agent, the solvent and the plasticizer are contained in the styrene-based resin particles is appropriately selected depending on the particle size of the styrene-based resin particles.
The temperature is about 120 ° C, preferably 70 to 100 ° C. 60
If the temperature is lower than ℃, the processing time is undesirably long. Also,
When the temperature exceeds 120 ° C., the number of bonded particles between the resin particles increases, which is not preferable.
【００４１】スチレン系樹脂粒子には、従来から発泡性
スチレン系樹脂粒子の製造に使用されているその他の添
加剤を加えてもよい。そのような添加剤としては、例え
ば、発泡セル造核剤、充填剤、滑剤、着色剤等が挙げら
れる。なお、これらの添加剤の使用量は、発泡成形体の
気泡膜厚を薄くさせず、かつ気泡膜が破れやすくならな
い程度に調整される。また、得られる発泡成形体を建材
用断熱材として使用する場合は、成形体表面に難燃剤お
よび難燃助剤を付着させる方法もあるが、発泡成形体に
均一に難燃性を付与するためには、スチレン系単量体の
重合時または発泡剤の含浸時に難燃剤および難燃助剤を
添加するのが好ましい。The styrene resin particles may contain other additives conventionally used for producing expandable styrene resin particles. Examples of such additives include a foam cell nucleating agent, a filler, a lubricant, a coloring agent, and the like. The amount of these additives used is adjusted so that the cell thickness of the foamed molded article is not reduced and the cell membrane is not easily broken. Further, when the obtained foamed molded article is used as a heat insulating material for building materials, there is a method of attaching a flame retardant and a flame retardant auxiliary to the surface of the molded article, but in order to uniformly impart flame retardancy to the foamed molded article. It is preferable to add a flame retardant and a flame retardant aid during the polymerization of the styrene monomer or the impregnation of the blowing agent.
【００４２】難燃剤としては、一般に難燃性スチレン系
樹脂発泡体の製造に用いられているものを使用すること
ができ、具体的にはテトラブロモシクロオクタン、ヘキ
サブロモシクロドデカン、トリスジブロモプロピルホス
フェート、テトラブロモビスフェノールＡ等の有機水素
または塩素系難燃剤が挙げられる。難燃剤の使用割合
は、スチレン系樹脂粒子に対して０．５〜１．５重量％
が好ましい。難燃剤の使用割合が０．５重量％を下回る
と充分な難燃効果が期待できず、また１．５重量％を上
回ると成形性を低下させ易いので好ましくない。As the flame retardant, those generally used for producing a flame-retardant styrenic resin foam can be used, and specific examples thereof include tetrabromocyclooctane, hexabromocyclododecane, trisdibromopropyl phosphate. And organic hydrogen such as tetrabromobisphenol A or a chlorine-based flame retardant. The proportion of the flame retardant used is 0.5 to 1.5% by weight based on the styrene resin particles.
Is preferred. If the use ratio of the flame retardant is less than 0.5% by weight, a sufficient flame retarding effect cannot be expected, and if it exceeds 1.5% by weight, the moldability tends to deteriorate, which is not preferable.
【００４３】また、難燃助剤としては、例えば、ジクミ
ルパーオキサイド等の有機過酸化物が挙げられる。難燃
助剤の添加割合は、スチレン系樹脂粒子に対して０．０
５〜０．５重量％が好ましい。難燃助剤の添加割合が
０．０５重量％を下回ると充分な難燃効果が期待でき
ず、また０．５重量％を上回ると成形性を低下させる要
因となるので好ましくない。Examples of the flame retardant aid include organic peroxides such as dicumyl peroxide. The addition ratio of the flame retardant aid is 0.0
5 to 0.5% by weight is preferred. If the addition ratio of the flame retardant auxiliary is less than 0.05% by weight, a sufficient flame retarding effect cannot be expected, and if it exceeds 0.5% by weight, the moldability is reduced, which is not preferable.
【００４４】発泡性スチレン系樹脂粒子の発泡性の評価
は、次の条件で行った。発泡性スチレン系樹脂粒子を、
発泡槽中でゲージ圧０．７ｋｇｆ／ｃｍ2の蒸気にて加
熱発泡させた。このとき、加熱時間を１、３、４、５分
と変化させ、発泡粒子に収縮が発生する直前の発泡粒子
の嵩密度を測定し、最低発泡嵩密度とした。なお、最低
発泡嵩密度は、発泡粒子１０ｇをメスシリンダーに入れ
て体積を測定し、重量１０ｇを体積で除して嵩密度（ｇ
／ｃｍ3）とすることにより算出される。得られる最低
発泡嵩密度から、発泡性スチレン系樹脂粒子の発泡性
を、表１に示す基準で評価した。The evaluation of the expandability of the expandable styrene resin particles was performed under the following conditions. Expandable styrene resin particles,
The foam was heated and foamed with steam having a gauge pressure of 0.7 kgf / cm 2 in a foaming tank. At this time, the heating time was changed to 1, 3, 4, and 5 minutes, and the bulk density of the foamed particles immediately before shrinkage of the foamed particles was measured, and the result was defined as the minimum foamed bulk density. The minimum foaming bulk density was determined by measuring the volume of 10 g of foamed particles in a measuring cylinder, dividing the weight by 10 g by the volume, and calculating the bulk density (g).
/ Cm 3 ). The expandability of the expandable styrene-based resin particles was evaluated from the obtained minimum expanded bulk density according to the criteria shown in Table 1.
【００４５】上記発泡性スチレン系樹脂粒子を、加熱し
て予備発泡することにより、予備発泡粒子が製造でき
る。予備発泡には、例えば、水蒸気等で発泡する汎用の
ポリスチレン用予備発泡機を用いることができる。予備
発泡粒子は、通常、嵩密度が０．０２〜０．００９ｇ／
ｃｍ3程度であり、好ましくは０．０１６〜０．００９
ｇ／ｃｍ3である。嵩密度が０．０２ｇ／ｃｍ3を上回る
と、発泡成形体の重量が重くなり、コストアップとなっ
て好ましくない。また、嵩密度が０．００９ｇ／ｃｍ3
を下回ると、コストメリットはあるが、発泡成形体に収
縮等が発生しやすく、断熱性が低下するので好ましくな
い。Pre-expanded particles can be produced by heating and pre-expanding the expandable styrene resin particles. For the prefoaming, for example, a general-purpose polystyrene prefoaming machine that foams with steam or the like can be used. The pre-expanded particles usually have a bulk density of 0.02 to 0.009 g /
cm 3 , preferably 0.016 to 0.009
g / cm 3 . If the bulk density exceeds 0.02 g / cm 3 , the weight of the foamed molded article increases, and the cost increases, which is not preferable. Further, the bulk density is 0.009 g / cm 3
When the value is less than the above, there is a cost merit, but it is not preferable because shrinkage or the like is apt to occur in the foamed molded article, and the heat insulating property is reduced.
【００４６】予備発泡粒子は、通常、平均気泡膜厚が
０．８〜２．５μｍ程度であり、好ましくは１．０〜
２．５μｍである。本発明で得られる予備発泡粒子の気
泡膜は皺がなく、滑らかな表面を有する。予備発泡粒子
の平均気泡膜厚は、予備発泡粒子の断面を走査型電子顕
微鏡［Ｓ−３０００Ｎ：（株）日立製作所製］で観察
し、１０個所以上の気泡膜厚を測定し、その平均値を算
出することにより求めた。また、予備発泡粒子の気泡膜
状態は、上記の走査型電子顕微鏡を用いて目視観察し、
表１に示す基準で評価した。The pre-expanded particles usually have an average cell thickness of about 0.8 to 2.5 μm, preferably 1.0 to 2.5 μm.
2.5 μm. The cell membrane of the pre-expanded particles obtained in the present invention has no wrinkles and has a smooth surface. The average cell thickness of the pre-expanded particles is determined by observing the cross section of the pre-expanded particles with a scanning electron microscope [S-3000N: manufactured by Hitachi, Ltd.], measuring the cell thickness at 10 or more locations, and calculating the average value. Was calculated. In addition, the state of the bubble film of the pre-expanded particles is visually observed using the above scanning electron microscope,
The evaluation was performed according to the criteria shown in Table 1.
【００４７】上記のようにして得られる予備発泡粒子
を、加熱して発泡成形することにより、スチレン系樹脂
発泡成形体を製造することができる。具体的には、予備
発泡粒子を成形型内に充填し、水蒸気等で再加熱して、
予備発泡粒子どうしを融着させて、所望の形の発泡成形
体を製造する。発泡成形には、従来から使用されている
発泡スチレン系樹脂用成形機が用いられる。By heating and foaming the pre-expanded particles obtained as described above, a foamed styrene resin article can be produced. Specifically, the pre-expanded particles are filled in a mold, reheated with steam or the like,
The pre-expanded particles are fused together to produce a foam molded article having a desired shape. For the foam molding, a molding machine for a foamed styrene-based resin which has been conventionally used is used.
【００４８】予備発泡粒子を発泡成形する前は、予備発
泡粒子を常圧にて保管する熟成を行ってもよい。熟成に
好適な温度は、通常、２０〜６０℃程度である。熟成温
度が２０℃を下回ると熟成時間が長くなり、６０℃を上
回ると予備発泡粒子中の発泡剤が逸散し、成形性が低下
するので好ましくない。また、熟成時間は、特に限定さ
れず、予備発泡粒子の大きさ等により適宜選択される
が、例えば、熟成温度２０℃では２４時間程度である。Before foaming the pre-expanded particles, the pre-expanded particles may be aged to be stored at normal pressure. The temperature suitable for aging is usually about 20 to 60 ° C. If the aging temperature is lower than 20 ° C., the aging time is prolonged. If the aging temperature is higher than 60 ° C., the blowing agent in the pre-expanded particles escapes, and the moldability is undesirably reduced. The aging time is not particularly limited, and is appropriately selected depending on the size of the pre-expanded particles. For example, at an aging temperature of 20 ° C., about 24 hours.
【００４９】上記のようにして得られる発泡成形体の外
観および断熱性は表１に示す基準で評価した。なお、外
観は発泡成形体を直接目視して評価し、断熱性は発泡成
形体の熱伝導率を測定して評価した。熱伝導率は次の条
件で求めた。 準拠基準：ＪＩＳ Ａー１４１２ 装置：ＡＵＴＯ−Λ ＨＣー０７２［英弘精機（株）
製］ 試験片：（ｗ）２００×（Ｌ）２００×（ｔ）３０（ｍ
ｍ） 測定方法：平板熱流計法（測定温度２０℃）The appearance and heat insulating properties of the foam molded article obtained as described above were evaluated according to the criteria shown in Table 1. The appearance was evaluated by directly observing the foamed molded article, and the heat insulating property was evaluated by measuring the thermal conductivity of the foamed molded article. The thermal conductivity was determined under the following conditions. Compliant standard: JIS A-1412 Equipment: AUTO-Λ HC-072 [Hideki Seiki Co., Ltd.
Test piece: (w) 200 × (L) 200 × (t) 30 (m
m) Measurement method: Flat plate heat flow meter method (measuring temperature 20 ° C)
【００５０】本発明の発泡成形体は、形状を自由に選択
でき、かつ優れた断熱性を有するから、建築用断熱材、
食品用保温剤、魚箱、保冷コンテナー、贈答用保温容器
等に好適に使用される。The foamed molded article of the present invention can be freely selected in shape and has excellent heat insulating properties.
It is suitably used as a food heat insulator, a fish box, a cold container, a gift warming container, and the like.
【００５１】[0051]
【表１】 [Table 1]
【００５２】[0052]
【実施例】以下、本発明を実施例および比較例に基づき
詳細に説明するが、本発明はこれらの実施例により限定
されるものではない。EXAMPLES The present invention will be described in detail below with reference to examples and comparative examples, but the present invention is not limited to these examples.
【００５３】製造例 （懸濁重合によるスチレン樹脂粒子の製造）内容量１０
０Ｌの攪拌機付き重合容器に、水４０．０Ｌ、第三リン
酸カルシウム（懸濁剤）１００ｇおよびドデシルベンゼ
ンスルホン酸カルシウム（界面活性剤）２．０ｇを入
れ、続いて攪拌しながらスチレン４０．０ｋｇ、ベンゾ
イルパーオキサイド（重合開始剤）９６．０ｇ、ｔ−ブ
チルパーオキシベンゾエート（重合開始剤）２８．０ｇ
を添加し、９０℃に昇温して重合温度とした。そしてこ
の温度で６時間保持し、さらに１２５℃に昇温してから
２時間後冷却し、スチレン樹脂粒子（Ａ）を得た。この
スチレン樹脂粒子（Ａ）は、重量平均分子量Ｍｗが１７
万、膨張割合ＳＲが１．２であった。Production Example (Production of Styrene Resin Particles by Suspension Polymerization) Content 10
In a 0 L polymerization vessel equipped with a stirrer, 40.0 L of water, 100 g of tribasic calcium phosphate (suspension agent) and 2.0 g of calcium dodecylbenzenesulfonate (surfactant) were added, followed by stirring with 40.0 kg of styrene and benzoyl. 96.0 g of peroxide (polymerization initiator), 28.0 g of t-butyl peroxybenzoate (polymerization initiator)
Was added, and the temperature was raised to 90 ° C. to obtain the polymerization temperature. Then, the temperature was maintained at this temperature for 6 hours, and the temperature was further raised to 125 ° C., and then cooled after 2 hours to obtain styrene resin particles (A). The styrene resin particles (A) have a weight average molecular weight Mw of 17
The expansion ratio SR was 1.2.
【００５４】実施例１ スチレン樹脂粒子（Ａ）を篩分けして粒子径０．６〜
０．９ｍｍのスチレン樹脂粒子（Ｂ）を得た。内容量５
Ｌの攪拌機付き重合容器に、水２．０Ｌ、スチレン樹脂
粒子（Ｂ）５００ｇ、ピロリン酸マグネシウム（懸濁
剤）６．０ｇおよびドデシルベンゼンスルホン酸カルシ
ウム（界面活性剤）０．３ｇを入れ、攪拌しながら７０
℃に昇温した。次にベンゾイルパーオキサイド（重合開
始剤）４．５ｇ、ｔ−ブチルパーオキシベンゾエート
（重合開始剤）１．１ｇをスチレン２００ｇに溶解し、
重合容器に入れた。３０分後９０℃に昇温し、あらかじ
めジビニルベンゼン（多官能性モノマー）０．３５ｇ
（０．０１４ｍｏｌ％）を溶解したスチレン１３００ｇ
を２時間かけてポンプで一定量づつ重合容器に供給し
た。この際、１０分ごとに重合中のスチレン系樹脂粒子
の重合転化率を測定したところ、最低重合転化率は８７
％であった。スチレンの供給が終了した後、１２５℃に
昇温してから２時間保持した後、冷却してスチレン系樹
脂粒子（Ｃ）を得た。このスチレン系樹脂粒子（Ｃ）
は、Ｍｗが４０万、ＳＲが２．３であった。Example 1 Styrene resin particles (A) were sieved to a particle size of 0.6 to
0.9 mm of styrene resin particles (B) were obtained. Contents 5
2.0 L of water, 500 g of styrene resin particles (B), 6.0 g of magnesium pyrophosphate (suspension agent) and 0.3 g of calcium dodecylbenzenesulfonate (surfactant) are put into a polymerization container equipped with a stirrer L and stirred. While 70
The temperature was raised to ° C. Next, 4.5 g of benzoyl peroxide (polymerization initiator) and 1.1 g of t-butyl peroxybenzoate (polymerization initiator) were dissolved in 200 g of styrene.
It was placed in a polymerization vessel. 30 minutes later, the temperature was raised to 90 ° C., and 0.35 g of divinylbenzene (polyfunctional monomer) was previously obtained.
(0.014 mol%) dissolved 1300 g of styrene
Was supplied to the polymerization vessel in a fixed amount by a pump over 2 hours. At this time, the polymerization conversion rate of the styrene resin particles during polymerization was measured every 10 minutes, and the minimum polymerization conversion rate was 87.
%Met. After the supply of styrene was completed, the temperature was raised to 125 ° C., and the temperature was maintained for 2 hours, followed by cooling to obtain styrene resin particles (C). The styrene resin particles (C)
Had an Mw of 400,000 and an SR of 2.3.
【００５５】内容量５Ｌの攪拌機付き重合容器に、水
２．２Ｌ、スチレン系樹脂粒子（Ｃ）１８００ｇ、ピロ
リン酸マグネシウム（懸濁剤）６．０ｇおよびドデシル
ベンゼンスルホン酸カルシウム（界面活性剤）０．４ｇ
を入れ、攪拌しながら７０℃に昇温した。次いで、テト
ラブロモシクロオクタン（難燃剤）２３．４ｇ、ジクミ
ルパーオキサイド（難燃助剤）５．４ｇ、ジイソブチル
アジペート（可塑剤）１４．４ｇを重合容器内に入れ密
閉し９０℃に昇温した。昇温後、ブタン（発泡剤）１６
２ｇを圧入し６時間保持した。その後３０℃以下まで冷
却し、発泡性スチレン系樹脂粒子を得た。取出した発泡
性スチレン系樹脂粒子を乾燥した後、あらかじめポリエ
チレングリコール（帯電防止剤）、ステアリン脂亜鉛
（結合防止剤）、ヒドロキシステアリン酸トリグリセリ
ド（結合防止剤）を、発泡性スチレン系樹脂粒子に対し
て各０．０５重量％塗布して１３℃の恒温室で５日間管
理した後、発泡剤含有量をガスクロマトグラフィーにて
測定したところ、５．１％であった。次いで、発泡性ス
チレン系樹脂粒子を、ポリスチレン用予備発泡機で嵩密
度０．０１２５ｇ／ｃｍ3に予備発泡した。予備発泡
後、２０℃で２４時間熟成した。得られた予備発泡粒子
を電子顕微鏡にて観察し、気泡膜厚および気泡膜の状態
を確認したところ、平均気泡膜厚は１．５４μｍであ
り、気泡膜の皺は非常に少ないものであった。なお、こ
の予備発泡粒子の電子顕微鏡写真を図１に示す。In a 5 L polymerization vessel equipped with a stirrer, 2.2 L of water, 1800 g of styrene resin particles (C), 6.0 g of magnesium pyrophosphate (suspension) and 0 g of calcium dodecylbenzenesulfonate (surfactant) were added. 0.4g
And the temperature was raised to 70 ° C. while stirring. Next, 23.4 g of tetrabromocyclooctane (flame retardant), 5.4 g of dicumyl peroxide (flame retardant aid), and 14.4 g of diisobutyl adipate (plasticizer) are placed in a polymerization vessel, sealed, and heated to 90 ° C. did. After heating, butane (foaming agent) 16
2 g was injected and held for 6 hours. Thereafter, the mixture was cooled to 30 ° C. or lower to obtain expandable styrene resin particles. After drying the extracted expandable styrene resin particles, the polyethylene glycol (antistatic agent), zinc stearate (binding inhibitor), and hydroxystearic acid triglyceride (antibonding agent) are added to the expandable styrene resin particles in advance. After applying 0.05% by weight of each and controlling in a thermostat at 13 ° C. for 5 days, the content of the blowing agent was measured by gas chromatography and found to be 5.1%. Next, the expandable styrene-based resin particles were prefoamed to a bulk density of 0.0125 g / cm 3 by a prefoaming machine for polystyrene. After prefoaming, aging was performed at 20 ° C. for 24 hours. Observation of the obtained pre-expanded particles with an electron microscope confirmed the cell film thickness and the state of the cell film. The average cell film thickness was 1.54 μm, and the wrinkles of the cell film were very small. . An electron micrograph of the pre-expanded particles is shown in FIG.
【００５６】次に、予備発泡粒子を、発泡スチレン系樹
脂用成形機（積水工機社製 ＡＣＥ−１１ＱＳ）で成形
し、成形品寸法４００×３００×３０（ｍｍ）の板状の
発泡成形体を製造した。この発泡成形体を５０℃の乾燥
室で６時間養成した後発泡体密度を測定したところ、
０．０１２５ｇ／ｃｍ3であった。この発泡成形体は、
収縮もなく、外観も非常に優れたものであった。また、
発泡成形体は、熱伝導率が０．０３４（ｗ／ｍｋ）と低
く、断熱性に非常に優れるものであることが分かった。Next, the pre-expanded particles are molded by a molding machine for foamed styrene resin (ACE-11QS manufactured by Sekisui Koki Co., Ltd.), and a plate-shaped foam molded article having a molded article size of 400 × 300 × 30 (mm) is formed. Was manufactured. After this foam molded body was cultivated for 6 hours in a drying room at 50 ° C., the foam density was measured.
It was 0.0125 g / cm 3 . This foam molded body is
There was no shrinkage and the appearance was very good. Also,
It was found that the foamed molded product had a low thermal conductivity of 0.034 (w / mk) and was very excellent in heat insulation.
【００５７】実施例２ シード重合によりスチレン系樹脂粒子（Ｃ）を製造する
際に添加するジビニルベンゼン量を０．２８ｇ（０．０
１１ｍｏｌ％）とした以外は、実施例１と同様にして発
泡性スチレン系樹脂粒子、予備発泡粒子および発泡成形
体を得た。なお、シード重合によって得られたスチレン
系樹脂粒子は、Ｍｗが３５万、ＳＲが１．６であった。
得られた発泡成形体は、密度が０．０１２７ｇ／ｃｍ3
であり、発泡性、外観ともに非常に良好であった。ま
た、平均気泡膜厚は１．４１μｍであり、熱伝導率は
０．０３３Ｗ／ｍｋであった。Example 2 The amount of divinylbenzene added to produce styrene resin particles (C) by seed polymerization was 0.28 g (0.08 g).
11 mol%) to obtain expandable styrene resin particles, pre-expanded particles, and an expanded molded article in the same manner as in Example 1. The styrene resin particles obtained by seed polymerization had Mw of 350,000 and SR of 1.6.
The obtained foamed molded article has a density of 0.0127 g / cm 3.
And both foamability and appearance were very good. Further, the average bubble film thickness was 1.41 μm, and the thermal conductivity was 0.033 W / mk.
【００５８】実施例３ シード重合によりスチレン系樹脂粒子（Ｃ）を製造する
際に添加するジビニルベンゼン量を０．６ｇ（０．０２
４ｍｏｌ％）とした以外は、実施例１と同様にして発泡
性スチレン系樹脂粒子、予備発泡粒子および発泡成形体
を得た。なお、シード重合によって得られたスチレン系
樹脂粒子は、Ｍｗが５２万、ＳＲが２．４であった。得
られた発泡成形体は、密度が０．０１２８ｇ／ｃｍ3で
あり、発泡性、外観等も良好であった。また、平均気泡
膜厚は１．５５μｍであり、熱伝導率は０．０３１Ｗ／
ｍｋであった。Example 3 The amount of divinylbenzene added to produce styrene resin particles (C) by seed polymerization was 0.6 g (0.02 g).
4 mol%) to obtain expandable styrenic resin particles, pre-expanded particles, and an expanded molded article in the same manner as in Example 1. The styrene resin particles obtained by seed polymerization had an Mw of 520,000 and an SR of 2.4. The obtained foamed molded article had a density of 0.0128 g / cm 3 and also had good foaming properties and appearance. The average bubble thickness was 1.55 μm, and the thermal conductivity was 0.031 W /
mk.
【００５９】比較例１ シード重合によりスチレン系樹脂粒子（Ｃ）を製造する
際に添加するジビニルベンゼン量を０．１４７ｇ（０．
００５９ｍｏｌ％）として、得られるスチレン系樹脂粒
子のＭｗを２８万、ＳＲを１．３とした以外は、実施例
１と同様にして発泡性スチレン系樹脂粒子、予備発泡粒
子および発泡成形体を得た。得られた発泡成形体は、密
度が０．０１６ｇ／ｃｍ3であったが、気泡膜に皺が数
多く見られた。また、平均気泡膜厚は１．２１μｍであ
り、熱伝導率は０．０４５Ｗ／ｍｋであった。ここで得
られた予備発泡粒子の電子顕微鏡写真を図２に示す。Comparative Example 1 The amount of divinylbenzene added when producing styrene resin particles (C) by seed polymerization was 0.147 g (0.
0059 mol%), the expandable styrene resin particles, the pre-expanded particles, and the foamed molded article were obtained in the same manner as in Example 1 except that the Mw of the obtained styrene resin particles was 280,000 and the SR was 1.3. Was. Although the density of the obtained foam molded article was 0.016 g / cm 3 , many wrinkles were observed in the cell membrane. Further, the average bubble film thickness was 1.21 μm, and the thermal conductivity was 0.045 W / mk. FIG. 2 shows an electron micrograph of the pre-expanded particles obtained here.
【００６０】比較例２ シード重合によりスチレン系樹脂粒子（Ｃ）を製造する
際に添加するジビニルベンゼン量を０．７５ｇ（０．０
３ｍｏｌ％）として、得られるスチレン系樹脂粒子のＭ
ｗを６３万、ＳＲを３．７とした以外は、実施例１と同
様にして発泡性スチレン系樹脂粒子、予備発泡粒子およ
び発泡成形体を得た。得られた発泡成形体は、密度が
０．０３３ｇ／ｃｍ3と発泡性に劣り、０．０２ｇ／ｃ
ｍ3を上回る所望の密度の発泡成形体を得ることができ
なかった。Comparative Example 2 The amount of divinylbenzene added when producing styrene resin particles (C) by seed polymerization was 0.75 g (0.05 g).
3 mol%), the M of the resulting styrene resin particles
Except that w was 630,000 and SR was 3.7, expandable styrene-based resin particles, pre-expanded particles, and an expanded molded article were obtained in the same manner as in Example 1. The obtained foamed molded article has a density of 0.033 g / cm 3 , which is inferior in foamability and 0.02 g / c.
A foamed molded article having a desired density exceeding m 3 could not be obtained.
【００６１】比較例３ シード重合によりスチレン系樹脂粒子（Ｃ）を製造する
際に気泡調整剤としてエチレンビスステアリン酸アミド
を０．２重量％添加して、嵩密度０．０１２５ｇ／ｃｍ
3に予備発泡したときの気泡膜厚を０．６５μｍとした
以外は、実施例１と同様にして発泡性スチレン系樹脂粒
子、予備発泡粒子および発泡成形体を得た。得られた予
備発泡粒子は、電子顕微鏡により皺の少ないものである
ことが観察された。しかしながら、この予備発泡粒子を
加熱成形して得られた発泡成形体は、熱伝導率が高く、
断熱性の劣るものであった。Comparative Example 3 In producing styrene resin particles (C) by seed polymerization, 0.2% by weight of ethylene bisstearic acid amide was added as a cell regulator, and the bulk density was 0.0125 g / cm.
In Example 3, expandable styrene-based resin particles, pre-expanded particles, and a foamed molded product were obtained in the same manner as in Example 1, except that the thickness of the cells when pre-expanded was changed to 0.65 μm. The obtained pre-expanded particles were observed by an electron microscope to have less wrinkles. However, the foam molded article obtained by heat molding the pre-expanded particles has a high thermal conductivity,
The insulation was poor.
【００６２】比較例４ シード重合によりスチレン系樹脂粒子（Ｃ）を製造する
際に重合温度およびスチレン系単量体の供給速度を変え
て最低重合転化率を９５％とした以外は、実施例１と同
様にして発泡性スチレン系樹脂粒子、予備発泡粒子およ
び発泡成形体を得た。嵩密度０．０１２５ｇ／ｃｍ3に
予備発泡した予備発泡粒子は、電子顕微鏡により気泡膜
厚が３．０５μｍであり、気泡膜の状態は皺の少ないも
のであることが観察された。しかしながら、この予備発
泡粒子を加熱成形して得られた発泡成形体は、熱伝導率
が高く、断熱性の劣るものであった。以上、各実施例お
よび比較例におけるスチレン系樹脂粒子のＭｗとＳＲ、
および予備発泡粒子の発泡性と平均気泡膜厚、気泡膜状
態、ならびに発泡成形体の外観と熱伝導率の結果を表２
に示す。Comparative Example 4 Example 1 was repeated except that the polymerization temperature and the feed rate of the styrene monomer were changed to a minimum polymerization conversion of 95% when producing the styrene resin particles (C) by seed polymerization. In the same manner as in the above, expandable styrene-based resin particles, pre-expanded particles and expanded molded articles were obtained. The pre-expanded particles pre-expanded to a bulk density of 0.0125 g / cm 3 had a cell thickness of 3.05 μm by electron microscopy, and the state of the cell membrane was observed to be less wrinkled. However, the foamed molded article obtained by heat-molding the pre-expanded particles had high thermal conductivity and poor heat insulation. As described above, Mw and SR of the styrene-based resin particles in each of Examples and Comparative Examples,
Table 2 shows the foaming properties of the pre-expanded particles, the average cell thickness, the cell membrane state, and the appearance and thermal conductivity of the foamed molded article.
Shown in
【００６３】[0063]
【表２】 [Table 2]
【００６４】表２より、比較例１および比較例２では、
ＭｗおよびＳＲの値が本発明の範囲外にあるスチレン系
樹脂粒子を用いたので、比較例１の予備発泡粒子では気
泡膜に皺が多く見られて状態が劣り、比較例２の予備発
泡粒子では発泡性に劣ることが分かる。また、比較例３
では予備発泡粒子の平均気泡膜厚が０．６５μｍと本発
明の範囲を下回り、比較例４では最低重合転化率が９５
重量％と本発明の範囲を超え、予備発泡粒子の平均気泡
膜厚が３．０５μｍと本発明の範囲を超えるので、両比
較例ともに熱伝導率が大きくなり断熱性が低下すること
が分かる。As shown in Table 2, in Comparative Examples 1 and 2,
Since the styrene-based resin particles having Mw and SR values outside the range of the present invention were used, the pre-expanded particles of Comparative Example 1 had many wrinkles in the cell membrane and were inferior in state. It can be seen that the foamability is poor. Comparative Example 3
In Comparative Example 4, the average cell film thickness of the pre-expanded particles was 0.65 μm, which is lower than the range of the present invention.
%, Which exceeds the range of the present invention, and the average cell thickness of the pre-expanded particles is 3.05 μm, which exceeds the range of the present invention.
【００６５】一方、Ｍｗが３０万〜６０万、ＳＲが１．
５〜３．０の範囲にあるスチレン系樹脂粒子を用いた、
発泡性がよく、平均気泡膜厚が０．８〜２．５μｍで、
かつ気泡膜に皺の発生がより少ない実施例１〜３の予備
発泡粒子を加熱成形して得られた発泡成形体は熱伝導率
の小さい断熱性に優れたものである。On the other hand, Mw is 300,000 to 600,000 and SR is 1.
Using styrene resin particles in the range of 5 to 3.0,
Good foaming, average cell thickness of 0.8 to 2.5 μm,
The foamed molded article obtained by heat-molding the pre-expanded particles of Examples 1 to 3 in which wrinkles are less generated in the cell membrane is excellent in heat insulation with small thermal conductivity.
【００６６】[0066]
【発明の効果】本発明の発泡性スチレン系樹脂粒子によ
れば、気泡膜の破れ、皺の発生が非常に少なく、低密度
化しても断熱性に優れ、外観に優れるスチレン系樹脂発
泡成形体を提供することができる。この発泡成形体は、
形状が自由に選択できることから、魚箱、保冷コンテナ
ー、贈答用保温容器等に好適に使用できる。According to the expandable styrene-based resin particles of the present invention, the foamed styrene-based resin molded article having very little breakage and wrinkles of the cell membrane, excellent heat insulating properties even at a low density, and excellent appearance. Can be provided. This foam molded body is
Since the shape can be freely selected, it can be suitably used for a fish box, a cold storage container, a gift warming container and the like.
【図１】気泡膜状態が良好なスチレン系樹脂予備発泡粒
子（実施例１）の拡大断面写真である。FIG. 1 is an enlarged cross-sectional photograph of a styrene-based resin pre-expanded particle (Example 1) having a good bubble film state.
【図２】気泡膜状態が不良なスチレン系樹脂予備発泡粒
子（比較例１）の拡大断面写真である。FIG. 2 is an enlarged cross-sectional photograph of a styrene-based resin pre-expanded particle having a poor cell membrane state (Comparative Example 1).
Claims (8)
あり、かつメルトフロー測定時、オリフィスの内径をＢ
ｍｍ、樹脂ストランドの外径をＡｍｍとしたときの膨張
割合ＳＲ（Ａ／Ｂ）が１．５〜３．０であるスチレン系
樹脂粒子に発泡剤を含有させてなり、嵩密度０．０２〜
０．００９ｇ／ｃｍ3に発泡させたときの平均気泡膜厚
が０．８〜２．５μｍであることを特徴とする発泡性ス
チレン系樹脂粒子。The weight average molecular weight Mw is 300,000 to 600,000, and the inner diameter of the orifice is B when measuring the melt flow.
mm, styrene resin particles having an expansion ratio SR (A / B) of 1.5 to 3.0 when the outer diameter of the resin strand is A mm are made to contain a foaming agent, and have a bulk density of 0.02 to 2.0.
Expandable styrene-based resin particles characterized in that the average cell thickness when expanded to 0.009 g / cm 3 is 0.8 to 2.5 μm.
ーを０．０１〜０．０２５ｍｏｌ％共重合してなる請求
項１に記載の発泡性スチレン系樹脂粒子。2. The expandable styrene resin particles according to claim 1, wherein the styrene resin particles are obtained by copolymerizing 0.01 to 0.025 mol% of a polyfunctional monomer.
ン系樹脂粒子を加熱して予備発泡させてなり、嵩密度が
０．０２〜０．００９ｇ／ｃｍ3 、平均気泡膜厚が０．
８〜２．５μｍである予備発泡粒子。3. The foamable styrenic resin particles according to claim 1 or 2 are pre-foamed by heating, have a bulk density of 0.02 to 0.009 g / cm 3 , and an average cell thickness of 0.
Pre-expanded particles that are between 8 and 2.5 μm.
し、発泡成形してなるスチレン系樹脂発泡成形体。4. A foamed styrene resin article obtained by heating and foaming the pre-expanded particles according to claim 3.
む請求項４に記載のスチレン系樹脂発泡成形体。5. The foamed styrene resin article according to claim 4, wherein the foamed styrene resin article contains a flame retardant.
形体からなる建築用断熱材。6. An architectural heat insulating material comprising the styrene resin foam molded article according to claim 5.
形体からなる食品用保温材。7. A food heat insulating material comprising the foamed styrenic resin product according to claim 4.
した懸濁液にスチレン系単量体を添加してシード重合す
る際において、重合過程において推移する重合転化率の
最低値が８５〜９４重量％となるように制御しながらシ
ード重合してスチレン系樹脂粒子を製造し、該スチレン
系樹脂粒子に発泡剤を含有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方法。8. When seed polymerization is carried out by adding a styrenic monomer to a suspension in which styrenic resin particles are dispersed in an aqueous medium, the lowest polymerization conversion rate in the course of polymerization is from 85 to 94. A method for producing expandable styrene-based resin particles, comprising: producing styrene-based resin particles by performing seed polymerization while controlling the styrene-based resin particles so that the styrene-based resin particles have a weight percent;
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