JP2668384B2 - Method for producing modified polyethylene resin foam molded article - Google Patents
Method for producing modified polyethylene resin foam molded articleInfo
- Publication number
- JP2668384B2 JP2668384B2 JP63115397A JP11539788A JP2668384B2 JP 2668384 B2 JP2668384 B2 JP 2668384B2 JP 63115397 A JP63115397 A JP 63115397A JP 11539788 A JP11539788 A JP 11539788A JP 2668384 B2 JP2668384 B2 JP 2668384B2
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- Japan
- Prior art keywords
- weight
- parts
- polyethylene resin
- monomer
- vinyl aromatic
- 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.)
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Description
【発明の詳細な説明】 〔産業上の利用分野〕 本発明は改質された無架橋の直鎖状低密度ポリエチレ
ン樹脂発泡成形体の製造方法に関し、更に詳しくは、剛
性及び耐衝撃性の極めて優れた改質ポリエチレン系樹脂
発泡成形体の製造方法に関する。TECHNICAL FIELD The present invention relates to a method for producing a modified non-crosslinked linear low-density polyethylene resin foam-molded article, and more specifically, it has excellent rigidity and impact resistance. The present invention relates to a method for producing an excellent modified polyethylene resin foam molded article.
〔従来技術〕 一般に、ポリエチレン系樹脂の発泡体は弾性が高く、
繰り返しの応力に対しても歪の回復力が大きいという特
徴の他に、耐油性、耐衝撃性に優れるという長所を有し
ており、重要な包装資材として広く利用されている。し
かし、ポリエチレン系樹脂粒子を予備発泡粒子となし、
これを型内成形して発泡成形体を得る場合、ポリエチレ
ンの剛性の低さからその予備発泡粒子や型内成形後の発
泡成形体の収縮がおこりやすく、また得られた発泡成形
体は柔らかく、圧縮強度が低いという短所を有してい
る。[Prior art] In general, polyethylene resin foam has high elasticity,
In addition to the feature that strain recovery is large against repeated stress, it has the advantage of being excellent in oil resistance and impact resistance, and is widely used as an important packaging material. However, polyethylene-based resin particles and pre-expanded particles,
When this is molded in-mold to obtain a foamed molded product, the pre-foamed particles and the foamed molded product after in-mold molding tend to contract due to the low rigidity of polyethylene, and the resulting foamed molded product is soft, It has the disadvantage of low compressive strength.
このような欠点を改良する方法として、ポリエチレン
系樹脂にピニル芳香族モノマーを含浸させて重合を行
い、改質ポリエチレン系樹脂予備発泡粒子を得るという
方法が特公昭45−32623号、同51−46138号、同52−1015
0号、同59−3487号等により提案されている。しかし、
これらの方法ではビニル芳香族単量体のポリエチレン系
樹脂への含浸と重合が同時平行的に行われるため、粒子
表面と内部とで重合反応において不均一性が生じ、その
結果生成粒子の均質性が劣り、またポリエチレン系樹脂
に含浸される前に無視しえない量の該単量体が単独粒子
として重合してしまうという問題がある。As a method of improving such defects, a method of impregnating a polyethylene resin with a pinyl aromatic monomer and polymerizing the resin to obtain modified polyethylene resin pre-expanded particles is disclosed in JP-B-45-32623 and 51-46138. No. 52-1015
Nos. 0, 59-3487 and the like. But,
In these methods, since the impregnation of polyethylene resin with vinyl aromatic monomer and the polymerization are performed in parallel at the same time, non-uniformity occurs in the polymerization reaction between the particle surface and the inside, resulting in the homogeneity of the particles. In addition, there is a problem that a considerable amount of the monomer is polymerized as a single particle before being impregnated with the polyethylene resin.
これらの問題を解決するために特公昭58−53003号、
同58−51009号、同58−51010号では、ビニル系単量体及
び該単量体100重量部に対し0.01〜0.8重量部の重合開始
剤をポリエチレン系樹脂粒子に含浸重合する際、重合開
始剤の分解が実質的におこらない温度で該単量体の80％
以上を含浸させた後、温度を上昇させて重合を行うとい
う方法が開示されている。この方法によれば、含浸工程
と重合工程を分離することにより生成粒子の均質性が向
上し、ビニル系単量体の単独重合体が事実上生成しない
ことが記載されている。To solve these problems, Japanese Patent Publication No. 58-53003,
In No. 58-51009 and No. 58-51010, polymerization is initiated when impregnating and polymerizing 0.01 to 0.8 part by weight of a polymerization initiator with a vinyl-based monomer and 100 parts by weight of the monomer in polyethylene-based resin particles. 80% of the monomer at a temperature at which decomposition of the agent does not substantially occur
A method is disclosed in which, after impregnating the above, the temperature is raised to carry out the polymerization. According to this method, it is described that by separating the impregnation step and the polymerization step, the homogeneity of the produced particles is improved, and a homopolymer of vinyl monomer is practically not produced.
また、特開昭62−59642号には、高密度ポリエチレン
系樹脂粒子にスチレン系単量体を含浸重合する方法が記
載されているが、ゲル分率10〜40％の架橋化した粒子を
用いる必要がある。Further, JP-A-62-59642 describes a method of impregnating and polymerizing a high-density polyethylene resin particle with a styrene monomer, but using a crosslinked particle having a gel fraction of 10 to 40%. There is a need.
上記の如くビニル系単量体をポリエチレン系樹脂粒子
に含浸重合して得られる生成粒子は、ポリエチレン系樹
脂のマトリックス中にビニル系重合体粒子が分散してい
る海島構造を有しているが、前記従来技術による場合
は、架橋化が必要であったり、またビニル系重合体の分
散粒子径が大きく、該生成粒子を予備発泡し、更に加熱
成形して得られる発泡成形体は剛性、耐衝撃性ともに満
足し得るものではない。Particles obtained by impregnating and polymerizing the vinyl-based monomer into the polyethylene-based resin particles as described above have a sea-island structure in which the vinyl-based polymer particles are dispersed in the matrix of the polyethylene-based resin, In the case of the above-mentioned conventional technique, cross-linking is necessary, or the dispersed particle size of the vinyl polymer is large, and the foamed molded product obtained by pre-foaming the generated particles and further heat molding has rigidity and impact resistance. The sex is not satisfactory.
本発明は、ポリエチレン系樹脂本来の性質である耐衝
撃性に優れ、且つ剛性を改良した改質ポリエチレン系樹
脂発泡成形体を製造することを目的とし、無架橋の直鎖
状低密度ポリエチレン樹脂粒子にビニル芳香族単量体を
重合させうる重合開始剤の量を該単量体100重量部に対
し、1.0〜3.0重量部使用して生成粒子中のビニル芳香族
重合体の分散粒子径を小さくすることにより、優れた耐
衝撃性及び剛性を備えた成形品を製造する方法を提供す
るものである。The present invention aims to produce a modified polyethylene resin foamed molded article having excellent impact resistance, which is an inherent property of polyethylene resin, and having improved rigidity, and is a non-crosslinked linear low density polyethylene resin particle. The amount of the polymerization initiator capable of polymerizing the vinyl aromatic monomer to 100 parts by weight of the monomer is 1.0 to 3.0 parts by weight to reduce the dispersed particle diameter of the vinyl aromatic polymer in the produced particles. By doing so, a method for producing a molded article having excellent impact resistance and rigidity is provided.
即ち、本発明は無架橋の直鎖状低密度ポリエチレン樹
脂粒子100重量部、ビニル芳香族単量体５〜300重量部及
び該単量体100重量部に対し1.0〜3.0重量部の重合開始
剤を水性媒体中に分散させ、該単量体の重合が実質的に
おこらない温度に加熱して該単量体を前記ポリエチレン
系樹脂粒子の内部及び表面に含浸せしめた後、上記水性
懸濁液の温度を上昇させて該単量体の重合を行い該ポリ
エチレン系樹脂粒子中に平均粒子径0.05〜0.1μｍのビ
ニル芳香族重合体がミクロ分散した重合体粒子を得、重
合中もしくは重合終了後に前記重合体粒子に揮発性発泡
剤を含浸せしめ発泡させて得た予備発泡粒子を金型内に
充填し加熱融着して発泡成形体を得ることを特徴とする
改質ポリエチレン系樹脂予備発泡粒子の製造方法を内容
とするものである。That is, the present invention comprises 100 parts by weight of non-crosslinked linear low-density polyethylene resin particles, 5 to 300 parts by weight of vinyl aromatic monomer, and 1.0 to 3.0 parts by weight of a polymerization initiator based on 100 parts by weight of the monomer. In an aqueous medium and heated to a temperature at which polymerization of the monomer does not substantially occur to impregnate the inside and the surface of the polyethylene resin particles with the monomer, and then the above aqueous suspension. Polymerization of the monomer is carried out by increasing the temperature of to obtain polymer particles in which the vinyl aromatic polymer having an average particle diameter of 0.05 to 0.1 μm is micro-dispersed in the polyethylene resin particles, and during or after the completion of the polymerization. Modified polyethylene resin pre-expanded particles characterized in that pre-expanded particles obtained by impregnating a volatile foaming agent into the polymer particles and foaming are filled in a mold and heat-sealed to obtain an expanded molded article. The manufacturing method is as follows.
本発明において使用される無架橋の直鎖状低密度ポリ
エチレンは、エチレンとα−オレフィンとの共重合体が
好ましい。α−オレフィンとして例えば１−ブテン、１
−ペンテン、１−ヘキセン、3,3−ジメチル−１−ブテ
ン、４−メチル−１−ペンテン、4,4−ジメチル−１−
ペンテン、１−オクテン等が挙げられる。また、少量の
範囲で、低密度ポリエチレン、高密度ポリエチレン、エ
チレン・プロピレン共重合体、エチレンプロピレン・ブ
テン−１共重合体、エチレン・酢酸ビニル共重合体、エ
チレン−アクリル酸共重合体、エチレン−塩化ビニル共
重合体、これらの２種以上を併用してもよい。The non-crosslinked linear low-density polyethylene used in the present invention is preferably a copolymer of ethylene and α-olefin. As an α-olefin, for example, 1-butene, 1
-Pentene, 1-hexene, 3,3-dimethyl-1-butene, 4-methyl-1-pentene, 4,4-dimethyl-1-
Penten, 1-octene and the like can be mentioned. In a small amount, low density polyethylene, high density polyethylene, ethylene / propylene copolymer, ethylene propylene / butene-1 copolymer, ethylene / vinyl acetate copolymer, ethylene-acrylic acid copolymer, ethylene- You may use together two or more types of vinyl chloride copolymers.
形状はパウダー、ペレット状等の粒子状態であること
が好ましい。その平均粒径は0.05〜5mm程度が好適な範
囲である。0.05mmより小さい場合は発泡剤の逸散が激し
く、5mmを越える大きな粒子を用いた場合は重合時の分
散が困難であり、また成形時の充填性が悪くなるため好
ましくない。The shape is preferably a particle state such as a powder or a pellet. The average particle size is preferably about 0.05 to 5 mm. If it is smaller than 0.05 mm, the foaming agent is apt to be scattered, and if large particles larger than 5 mm are used, it is difficult to disperse it during polymerization and the filling property at the time of molding is deteriorated.
本発明において使用されるビニル芳香族単量体として
は、スチレンの他にメチルスチレン、ジメチルスチレ
ン、エチルスチレン、イソプロピルスチレン、クロルス
チレン等の核置換スチレン、α−メチルスチレン等のα
−置換スチレン等を単独又は２種以上の混合物、あるい
は上記単量体と共重合可能な少量の他の単量体、例えば
アクリロニトリル、アクリル酸エステル、メタクリル酸
エステル、ジビニルベンゼン、マレイン酸モノまたはジ
アルキル、その他との混合物が使用される。Examples of the vinyl aromatic monomer used in the present invention include, in addition to styrene, methylstyrene, dimethylstyrene, ethylstyrene, isopropylstyrene, nuclear-substituted styrene such as chlorostyrene, and α such as α-methylstyrene.
-Substituted styrene or the like alone or in a mixture of two or more kinds, or a small amount of another monomer copolymerizable with the above-mentioned monomer, for example, acrylonitrile, acrylic acid ester, methacrylic acid ester, divinylbenzene, mono- or dialkyl maleate. , And other mixtures are used.
ビニル芳香族単量体の量は、無架橋の直鎖状低密度ポ
リエチレン樹脂100重量部に対して５〜300重量部、好ま
しくは30〜200重量部である。300重量部を越えると、ビ
ニル芳香族単量体が該直鎖状低密度ポリエチレン樹脂に
均一に全部吸収されず、吸収されない単量体が単独で重
合してしまうため好ましくない。また多量にビニル芳香
族単量体を吸収した直鎖状低密度ポリエチレン樹脂は、
直鎖状低密度ポリエチレン特有の性質を失う結果とな
る。一方、ビニル芳香族単量体が５重量部未満では、直
鎖状低密度ポリエチレン樹脂の剛性の改良が十分なされ
ないため好ましくない。The amount of the vinyl aromatic monomer is 5 to 300 parts by weight, preferably 30 to 200 parts by weight, per 100 parts by weight of the non-crosslinked linear low density polyethylene resin. If it exceeds 300 parts by weight, the vinyl aromatic monomer is not uniformly and completely absorbed by the linear low-density polyethylene resin, and the unabsorbed monomer is polymerized by itself, which is not preferable. The linear low-density polyethylene resin that has absorbed a large amount of vinyl aromatic monomer is
This results in the loss of properties inherent in linear low density polyethylene. On the other hand, if the amount of the vinyl aromatic monomer is less than 5 parts by weight, the rigidity of the linear low-density polyethylene resin is not sufficiently improved, which is not preferable.
本発明において用いられる重合開始剤としては、一般
にビニル芳香族単量体の懸濁重合用開始剤として用いら
れているものをそのまま使用できる。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−ブ
チルパーオキサイド、ｔ−ブチルパーオキシベンゾエー
ト、1,1−ビス（ｔ−ブチルパーオキシ）3,3,5−トリメ
チルシクロヘキサン、ｔ−ブチルパーオキサイドイソプ
ロピルカーボネート、2,2−ビス（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等である。これらの重合開始剤
は単独また２種以上併用して用いてもよい。重合開始剤
は油溶性であるべきであり、ビニル芳香族単量体に溶解
させるか、又は重合反応に支障をきたない少量の溶剤、
例えばトルエン等に溶解させてビニル芳香族単量体と同
時又は別々に水性媒体中に添加される。重合開始剤の使
用量は、ビニル芳香族単量体100重量部に対し1.0〜3.0
重量部、好ましくは1.1〜2.0重量部である。1.0重量部
未満では、得られる改質ポリエチレン系樹脂粒子中のビ
ニル芳香族重合体の分散粒子径が大きく、該粒子を予備
発泡し、更に加熱成形して得られる発泡成形体は剛性が
改良されないばかりか、ポリエチレン系樹脂特有の耐衝
撃性が損なわれる。3.0重量部を越えて使用しても、必
要以上にビニル芳香族重合体の分子量が小さくなるため
好ましくない。As the polymerization initiator used in the present invention, those generally used as an initiator for suspension polymerization of a vinyl aromatic monomer can be used as they are. For example, benzoyl peroxide, lauroyl peroxide, t-butyl peroxide, t-butyl peroxybenzoate, 1,1-bis (t-butylperoxy) 3,3,5-trimethylcyclohexane, t-butyl peroxide isopropyl Organic peroxides such as carbonate, 2,2-bis (t-butylperoxy) butane and dicumyl peroxide; and azo compounds such as azoisobutyronitrile and azobisdimethylvaleronitrile. These polymerization initiators may be used alone or in combination of two or more. The polymerization initiator should be oil-soluble, dissolved in a vinyl aromatic monomer, or a small amount of a solvent that does not hinder the polymerization reaction,
For example, it is dissolved in toluene or the like and added to the aqueous medium simultaneously or separately with the vinyl aromatic monomer. The amount of the polymerization initiator used is 1.0 to 3.0 with respect to 100 parts by weight of the vinyl aromatic monomer.
Parts by weight, preferably 1.1 to 2.0 parts by weight. If the amount is less than 1.0 part by weight, the dispersion particle size of the vinyl aromatic polymer in the obtained modified polyethylene resin particles is large, the particles are pre-foamed, and the foam molded product obtained by further heat molding does not have improved rigidity. In addition, the impact resistance peculiar to the polyethylene resin is impaired. Even if it is used in excess of 3.0 parts by weight, the molecular weight of the vinyl aromatic polymer becomes smaller than necessary, which is not preferable.
重合開始剤量を1.0〜3.0重量部にすることによって、
生成重合粒子中のビニル芳香族重合体の分散粒子径を小
さくし、また一定以上の分子量に保つことが可能で、発
泡成形体の剛性及び耐衝撃性を飛躍的に向上させること
ができる。By setting the polymerization initiator amount to 1.0 to 3.0 parts by weight,
It is possible to reduce the dispersed particle size of the vinyl aromatic polymer in the generated polymerized particles and to keep the molecular weight above a certain level, and it is possible to dramatically improve the rigidity and impact resistance of the foamed molded product.
本発明において用いられる懸濁液としては、ポリビニ
ルアルコール、ポリビニルピロリドン、メチルセルロー
ス等の水溶性高分子物質；リン酸カルシウム、ピロリン
酸マグネシウム、酸化マグネシウム等の難溶性無機物
質、その他が使用される。As the suspension used in the present invention, water-soluble polymer substances such as polyvinyl alcohol, polyvinylpyrrolidone, and methyl cellulose; sparingly soluble inorganic substances such as calcium phosphate, magnesium pyrophosphate, magnesium oxide, and the like are used.
ビニル芳香族単量体の含浸は、撹拌下に該単量体の重
合が実質的におこらない条件下で加熱して行われる。含
浸温度は高いほうが含浸促進の点からは好ましいが、重
合開始剤の過早分解によって含浸前のビニル芳香族単量
体が重合してしまうので、適正な温度設定が必要であ
る。重量既知のポリエチレン系樹脂を大量のビニル芳香
族単量体に30分間浸漬した後の重量増加分をその温度で
の飽和含浸量とし、何点かの温度下でこの測定をするこ
とにより、仕込みビニル芳香族単量単量にに対する最適
含浸温度を設定することができる。含浸時間は30分から
３時間程度が好適である。The impregnation with the vinyl aromatic monomer is carried out by heating under stirring under the condition that the polymerization of the monomer does not substantially occur. A higher impregnation temperature is preferable from the viewpoint of promotion of impregnation, but the vinyl aromatic monomer before impregnation is polymerized due to premature decomposition of the polymerization initiator, so it is necessary to set an appropriate temperature. The weight-increased amount of a polyethylene-based resin of known weight after being dipped in a large amount of vinyl aromatic monomer for 30 minutes was used as the saturated impregnation amount at that temperature, and this measurement was performed at several points to prepare the charge. The optimum impregnation temperature can be set for the vinyl aromatic unit amount. The impregnation time is preferably from about 30 minutes to 3 hours.
ビニル芳香族単量体の含浸後、水性懸濁液の温度を再
び上昇させて撹拌下にビニル芳香族単量体の重合を行
う。重合開始剤の分解が十分におこる温度下で、重合時
間は一般に３〜20時間である。After impregnation with the vinyl aromatic monomer, the temperature of the aqueous suspension is raised again, and the vinyl aromatic monomer is polymerized with stirring. The polymerization time is generally 3 to 20 hours at a temperature at which the polymerization initiator is sufficiently decomposed.
本発明において用いられる発泡剤としては、生成した
改質ポリエチレン系樹脂粒子を溶解しないか、又は僅か
に膨潤させるにすぎない性質を持ったもので、常時常圧
で気体もしくは液体のものが用いられる。例えばｎ−プ
ロパン、ｎ−ブタン、イソブタン、ｎ−ペンタン、イソ
ペンタン、ネオペンタン、ｎ−ヘキサン、イソヘキサン
等の樹脂族炭化水素類、シクロブタン、シクロペンタン
等の脂環族炭化水素類、及びメチルクロライド、エチル
クロライド、メチレンクロライド、トリクロロフルオロ
メタン、ジクロロフルオロメタン、ジクロロジフルオロ
メタン、クロロジフルオロメタン、ジクロロテトラフル
オロエタン等のハロゲン化炭化水素類で、これらは単独
又は２種以上混合して用いることができる。The foaming agent used in the present invention has a property that it does not dissolve or slightly swell the produced modified polyethylene resin particles, and a gas or liquid that is always under normal pressure is used. . For example, resin group hydrocarbons such as n-propane, n-butane, isobutane, n-pentane, isopentane, neopentane, n-hexane, isohexane, cycloaliphatic hydrocarbons such as cyclobutane and cyclopentane, and methyl chloride, ethyl Halogenated hydrocarbons such as chloride, methylene chloride, trichlorofluoromethane, dichlorofluoromethane, dichlorodifluoromethane, chlorodifluoromethane, and dichlorotetrafluoroethane, which can be used alone or in combination of two or more.
上記の如くして得られた改質ポリエチレン系樹脂粒子
を予備発泡させる方法としては、公知技術である水蒸気
による方法と西独公開特許公報第2,107,683号、特公昭5
6−1344号等で提案されている方法のどちらを用いても
よい。例えば特公昭56−1344号の方法は、生成粒子を耐
圧容器中で揮発性発泡剤と懸濁剤の存在下で水性媒体中
に分散させ、この状態で加熱し揮発性発泡剤を粒子中に
含浸させた後、揮発性発泡剤の蒸気圧以上の加圧下で該
粒子の軟化温度以上に加熱した状態で該耐圧容器内圧を
一定に保ちながら、該耐圧容器から該粒子を水と共に低
圧域に放出するというものである。As a method for pre-foaming the modified polyethylene resin particles obtained as described above, a method using steam, which is a known technique, and West German Laid-Open Patent Publication No. 2,107,683, JP-B-5
Either of the methods proposed in 6-1344 or the like may be used. For example, in the method of Japanese Examined Patent Publication No. 56-1344, the generated particles are dispersed in an aqueous medium in the presence of a volatile foaming agent and a suspending agent in a pressure resistant container, and heated in this state to add the volatile foaming agent to the particles. After the impregnation, while maintaining the pressure inside the pressure vessel constant while heating the pressure above the softening temperature of the particles under a pressure higher than the vapor pressure of the volatile foaming agent, the pressure vessel moves the particles into a low pressure region together with water. It is to release it.
上記の如くして得られた予備発泡粒子は、閉鎖しうる
が密閉しえない金型内に充填し、加熱融着せしめて発泡
成形体とされる。得られた発泡成形体は、成形体密度19
g/以上でシャルピー衝撃値1.0以上の高い剛性と優れ
た耐衝撃性を有する。The pre-expanded particles obtained as described above are filled in a mold that can be closed but not sealed, and heat-fused to obtain a foamed molded product. The obtained foamed molded article has a molded article density of 19
It has high rigidity with a Charpy impact value of 1.0 or more at g / or more and excellent impact resistance.
本発明は、上述したように、無架橋の直鎖状低密度ポ
リエチレン樹脂粒子を使用し、ビニル芳香族単量体100
重量部に対し該単量体を重合させうる重合開始剤を1.0
〜3.0重量部使用することによって、重合後生成した樹
脂粒子中に存在するビニル芳香族重合体の分散粒子径が
0.05〜0.1μｍと従来法による粒子径の10分の１程度に
までミクロ分散させうる方法であり、当然のことながら
単純ブレンドでは到底達成しえないレベルのものであ
る。The present invention, as described above, uses non-crosslinked linear low-density polyethylene resin particles, the vinyl aromatic monomer 100
A polymerization initiator capable of polymerizing the monomer is used in an amount of 1.0 part by weight.
~ 3.0 parts by weight, the dispersion particle size of the vinyl aromatic polymer present in the resin particles produced after polymerization is
This is a method in which it can be micro-dispersed to 0.05 to 0.1 μm, which is about 1/10 of the particle diameter obtained by the conventional method, which is of course at a level that cannot be achieved by simple blending.
本発明により製造される改質ポリエチレン系樹脂予備
発泡粒子を閉鎖しうるが密閉しえない型内に充填し、加
熱成形して得られる発泡成形体は、従来のビニル芳香族
により改質されたポリエチレン系樹脂発泡成形体に比
べ、より高い剛性と優れた耐衝撃性を有し、緩衝材、包
装材、容器等に好適に用いられる。The foamed molded product obtained by filling the modified polyethylene resin pre-expanded particles produced by the present invention in a mold that can be closed but not sealed and heat-molding the product was modified with a conventional vinyl aromatic compound. It has higher rigidity and superior impact resistance than polyethylene-based resin foam molded articles, and is suitably used for cushioning materials, packaging materials, containers and the like.
以下、実施例により更に詳しく説明するが、本発明は
これらに限定されるものではない。Hereinafter, the present invention will be described in more detail by way of examples, but the present invention is not limited thereto.
実施例１〜５、比較例１〜４ 内容積3.5のオートクレーブに純水400重量部、密度
0.93g/cm2、MFR2.1g/10分の直鎖状低密度ポリエチレン
樹脂粒子（三井石油化学製「ウルトゼックス3021F」）1
00重量部、懸濁液としてα−オレフィンスルフォン酸ソ
ーダ0.1重量部、リン酸三カルシウム３重量部、更に重
合開始剤として第１表に示す量の1,1−ビス（ｔ−ブチ
ルパーオキシ）3,3,5−トリメチルシクロヘキサンを、
第１表に示す量のスチレン単量体に溶解したものを加え
て撹拌し、水性懸濁液とした。Examples 1 to 5, Comparative Examples 1 to 4 400 parts by weight of pure water in an autoclave with an internal volume of 3.5 and a density
0.93 g / cm 2 , MFR 2.1 g / 10 min linear low density polyethylene resin particles (“Ultzex 3021F” manufactured by Mitsui Petrochemical) 1
00 parts by weight, 0.1 part by weight of α-olefin sodium sulfonate as a suspension, 3 parts by weight of tricalcium phosphate, and 1,1-bis (t-butylperoxy) in the amount shown in Table 1 as a polymerization initiator. 3,3,5-trimethylcyclohexane,
What was dissolved in the amount of styrene monomer shown in Table 1 was added and stirred to obtain an aqueous suspension.
次いで、この水性懸濁液を第１表に示すスチレン単量
体及び重合開始剤の含浸温度で１時間保持し、スチレン
単量体及び重合開始剤をポリエチレン樹脂粒子中に含浸
せしめた。Then, this aqueous suspension was kept at the impregnation temperature of the styrene monomer and the polymerization initiator shown in Table 1 for 1 hour to impregnate the polyethylene resin particles with the styrene monomer and the polymerization initiator.
次に、この水性懸濁液の温度を115℃に昇温し、該温
度で４時間保持して重合を完結させた。Next, the temperature of this aqueous suspension was raised to 115 ° C., and the temperature was maintained for 4 hours to complete the polymerization.
70℃まで冷却後、ブタン（ｎ−ブタン75％、イソブタ
ン25％）30重量部を圧入し該温度で１時間保持した後、
冷却して樹脂粒子を取り出し、酸洗、水洗、及び乾燥し
た。After cooling to 70 ° C., 30 parts by weight of butane (n-butane 75%, isobutane 25%) was injected and maintained at the temperature for 1 hour.
After cooling, the resin particles were taken out, washed with acid, washed with water, and dried.
得られた発泡性粒子を水蒸気中で発泡させ、300×170
×40mmの閉鎖しうるが密閉しえない、多数の小孔を有す
る金型に充填し、1.0kgf/cm2の圧力の水蒸気を小孔から
注入し40秒加熱した後、90秒冷却して取り出した。The resulting expandable particles are expanded in steam to give 300 × 170
It is filled in a mold with a large number of small holes that can be closed, but cannot be closed, of 40 mm × 40 mm, and then steam with a pressure of 1.0 kgf / cm 2 is injected through the small holes and heated for 40 seconds, then cooled for 90 seconds. I took it out.
得られた発泡成形体の密度、融着度、圧縮強度、シャ
ルピー衝撃値を第１表に示す。Table 1 shows the density, fusion degree, compressive strength, and Charpy impact value of the obtained foamed molded product.
実施例６〜８、比較例５〜７ 上記重合開始剤の量及びスチレン単量体の量を第１表
に示す如く設定し、重合を完結させるまでは上記実施例
及び比較例と同様に行い、その後、60℃まで冷却してジ
クロロジフルオロメタン50重量部を圧入し再び昇温して
130℃に保持した。次いで、N2にて内圧を30kgf/cm2に保
持しながら容器の一端を開放して発泡を行った。得られ
た予備発泡粒子を実施例、比較例と同様に成形した。得
られた発泡成形体の物性を評価した結果を第１表に示
す。Examples 6 to 8 and Comparative Examples 5 to 7 The amounts of the above polymerization initiator and the amount of styrene monomer were set as shown in Table 1, and the same procedure as in the above Examples and Comparative Examples was conducted until the polymerization was completed. After that, cool to 60 ° C, press in 50 parts by weight of dichlorodifluoromethane, and raise the temperature again.
Hold at 130 ° C. Then, one end of the container was opened to perform foaming while maintaining the internal pressure at 30 kgf / cm 2 with N 2 . The obtained pre-expanded particles were molded in the same manner as in Examples and Comparative Examples. The results of evaluation of the physical properties of the obtained foamed molded product are shown in Table 1.
（註）（１）50％圧縮強度： JIS K 6767法に従って測定した。 (Note) (1) 50% compressive strength: Measured according to JIS K 6767 method.
（２）シャルピー衝撃値： 20×30×150mmの試験片（ノッチなし）でシャルピー
試験器をハンマー重量20kg、ハンマー角度124度、スパ
ン90mmに設定して測定した。(2) Charpy impact value: A Charpy tester with a 20 × 30 × 150 mm test piece (without notch) was set with a hammer weight of 20 kg, a hammer angle of 124 degrees, and a span of 90 mm.
（３）融着度： 成形体を引張りにより破断した時の破断面の破壊状態
で判断した。(3) Fusion degree: Judgment was made based on the fracture state of the fracture surface when the molded body was fractured by pulling.
◎：粒子表面露出が10％未満 ○：粒子表面露出が10〜40％未満 △：粒子表面露出が40〜70％未満 ×：粒子表面露出が70％以上：: Particle surface exposure is less than 10% ○: Particle surface exposure is less than 10 to 40% △: Particle surface exposure is less than 40 to 70% ×: Particle surface exposure is 70% or more
Claims (4)
子100重量部、ビニル芳香族単量体５〜300重量部及び該
単量体100重量部に対し1.0〜3.0重量部の重合開始剤を
水性媒体中に分散させ、該単量体の重合が実質的におこ
らない温度に加熱して該単量体を前記ポリエチレン系樹
脂粒子の内部及び表面に含浸せしめた後、上記水性懸濁
液の温度を上昇させて該単量体の重合を行い該ポリエチ
レン系樹脂粒子中に平均粒子径0.05〜0.1μｍのビニル
芳香族重合体がミクロ分散した重合体粒子を得、重合中
もしくは重合終了後に前記重合体粒子に揮発性発泡剤を
含浸せしめ発泡させて得た予備発泡粒子を金型内に充填
し加熱融着して発泡成形体を得ることを特徴とする改質
ポリエチレン系樹脂発泡成形体の製造方法。1. A non-crosslinked linear low-density polyethylene resin particle of 100 parts by weight, a vinyl aromatic monomer of 5 to 300 parts by weight, and a polymerization initiator of 1.0 to 3.0 parts by weight per 100 parts by weight of said monomer. In an aqueous medium and heated to a temperature at which polymerization of the monomer does not substantially occur to impregnate the inside and the surface of the polyethylene resin particles with the monomer, and then the above aqueous suspension. Polymerization of the monomer is carried out by increasing the temperature of to obtain polymer particles in which the vinyl aromatic polymer having an average particle diameter of 0.05 to 0.1 μm is micro-dispersed in the polyethylene resin particles, and during or after the completion of the polymerization. Modified polyethylene resin foamed molded article characterized in that pre-expanded particles obtained by impregnating a volatile foaming agent into the polymer particles and foaming are filled in a mold and heat-sealed to obtain a foamed molded article. Manufacturing method.
度ポリエチレン樹脂粒子100重量部に対して30〜200重量
部である請求項１記載の製造方法。2. The process according to claim 1, wherein the amount of the vinyl aromatic monomer is 30 to 200 parts by weight based on 100 parts by weight of the non-crosslinked linear low-density polyethylene resin particles.
部に対して1.1〜2.0重量部である請求項１又は２記載の
製造方法。3. The method according to claim 1, wherein the polymerization initiator is 1.1 to 2.0 parts by weight with respect to 100 parts by weight of the vinyl aromatic monomer.
ー衝撃値が1.0以上である請求項１、２又は３記載の製
造方法。4. The method according to claim 1, 2 or 3, wherein the foamed molded article has a density of 19 g / or more and a Charpy impact value of 1.0 or more.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP63115397A JP2668384B2 (en) | 1988-05-12 | 1988-05-12 | Method for producing modified polyethylene resin foam molded article |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP63115397A JP2668384B2 (en) | 1988-05-12 | 1988-05-12 | Method for producing modified polyethylene resin foam molded article |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH01284536A JPH01284536A (en) | 1989-11-15 |
| JP2668384B2 true JP2668384B2 (en) | 1997-10-27 |
Family
ID=14661552
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP63115397A Expired - Lifetime JP2668384B2 (en) | 1988-05-12 | 1988-05-12 | Method for producing modified polyethylene resin foam molded article |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP2668384B2 (en) |
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| JPS6259642A (en) * | 1985-09-09 | 1987-03-16 | Japan Styrene Paper Co Ltd | Pre-expanded particle of modified polyethylene resin and production thereof |
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| JPH01284536A (en) | 1989-11-15 |
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