JPS5841186B2 - Hatsupou Seikei Tai no Seizou Hohou - Google Patents

Description

【発明の詳細な説明】 本発明はエチレン系合成樹脂予備発泡粒子による発泡成
形体の製造方法の改良に関するものである。DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in a method for producing a foam molded article using pre-expanded particles of ethylene synthetic resin.

さらに詳しくいえば、本発明は予備発泡粒子に発泡用ガ
スを遺漏することなく、芯部まで均質に発泡した構造を
もつ発泡成形体を得る方法に関するものである。More specifically, the present invention relates to a method for obtaining a foam molded article having a structure in which the core portion is uniformly foamed without leaking foaming gas into the pre-expanded particles.

これまで、オレフィン系合成樹脂の予備発泡粒子を用い
型の寸法に忠実な成形体を得るための方法がいくつか提
案されている（例えば、特開昭４７−３４４５８号公報
、特開昭４９−８５１５８号公報、特開昭４９−１２８
０６５号公報参照）。Up to now, several methods have been proposed for obtaining molded articles faithful to the dimensions of the mold using pre-expanded particles of olefinic synthetic resin (for example, Japanese Patent Laid-Open No. 47-34458, Japanese Patent Laid-Open No. 49-1989) Publication No. 85158, Japanese Unexamined Patent Publication No. 49-128
(See Publication No. 065).

これらの方法は、いずれも架橋樹脂の予備発泡粒子に発
泡用ガス（発泡剤ガス、無機ガス）を遺漏した後発泡取
形する技術である。All of these methods are techniques in which foaming gas (foaming agent gas, inorganic gas) is leaked into pre-expanded particles of crosslinked resin, and then foaming is performed.

しかしながら、予備発泡粒子に発泡用ガスを遺漏するこ
とは多大の設備、経費を要する上に、遺漏後の発泡性粒
子を可及的速やかに使用しなげればならないという制限
を受けるためこれを省略することがこの種発泡成形技術
分野における１つの重要な課題となっていた。However, leaking the foaming gas into the pre-expanded particles requires a large amount of equipment and expense, and there is a restriction that the foamable particles after leakage must be used as soon as possible, so this is omitted. This has become an important issue in the field of foam molding technology.

本発明者らは、エチレン系合成樹脂の予備発泡粒子を、
なんら発泡用ガスの遺漏なしに発泡成形し、型の寸法に
忠実な、しかも内部まで均質な発泡成形体を製造する方
法を開発するために鋭意研究を重ねた結果、型成形後の
冷却条件を厳密に制御することにより容易にその目的を
達威しうろことを見出し、この知見に基いて本発明をな
すに至った。The present inventors have developed pre-expanded particles of ethylene-based synthetic resin,
As a result of intensive research to develop a method for foam molding without any leakage of foaming gas, faithful to the dimensions of the mold, and homogeneous inside, the cooling conditions after mold molding have been improved. It was discovered that the objective could be easily achieved through strict control, and based on this knowledge, the present invention was accomplished.

すなわち、本発明は、エチレン系合成樹脂発泡体粒子を
閉鎖型に充填後これに加熱することにより該粒子を膨張
させて型に合致した成形体を得る方法において、架橋し
たエチレン系合成樹脂から成り大気圧に近い内圧を有す
る予備発泡流子を非密閉性閉鎖型内に充填し、加熱して
成形したのち、成形体表面を９０〜４０℃の範囲内の温
度まで急冷し、次いで平均冷却速度０．０１〜０．３°
Ｃ／分で、３時間以上にわたって行う徐冷段階を経て室
温まで冷却することを特徴とする架橋エチレン系樹脂発
泡成形体の製造方法を提供するものである。That is, the present invention provides a method of filling a closed mold with ethylene-based synthetic resin foam particles and heating the same to expand the particles to obtain a molded article that conforms to the mold. After filling a non-sealable closed mold with a pre-foamed fluid having an internal pressure close to atmospheric pressure and molding by heating, the surface of the molded product is rapidly cooled to a temperature within the range of 90 to 40°C, and then the average cooling rate is 0.01~0.3°
The present invention provides a method for producing a crosslinked ethylene-based resin foam molded article, which is characterized by cooling to room temperature through an annealing step performed at C/min for 3 hours or more.

このように、本発明においては所定の予備発泡粒子を非
密閉性閉鎖型例えば有孔閉鎖型に充てんし、加熱して発
泡成形するとともに、その後の成形温度から室温までの
冷却速度を、先ず９０〜４０℃の範囲内の温度まで急冷
し、次いで平均冷却速度０．０１〜０．３℃／分で３時
間以上かげて室温にもたらすように制御することが必要
である。As described above, in the present invention, prescribed pre-expanded particles are filled into a non-sealable closed type, for example, a closed type with holes, and are foam-molded by heating, and the subsequent cooling rate from the molding temperature to room temperature is first controlled at 90°C. It is necessary to control the temperature to be rapidly cooled to a temperature in the range of ˜40° C. and then cool to room temperature at an average cooling rate of 0.01 to 0.3° C./min for 3 hours or more.

この冷却時間の上限は、基材樹脂の軟化温度以上に長時
間滞留することがなげれば特に制限はなく、２４時間、
４８時間という長い時間であってもよいが、作業効率の
点で通常は１０時間以内が選ばれる。The upper limit of this cooling time is not particularly limited as long as it does not stay above the softening temperature of the base resin for a long time.
Although it may be as long as 48 hours, from the point of view of work efficiency, 10 hours or less is usually selected.

このようにして、最初成形温度から９０℃ないし４０℃
の間の温度まで急冷し、次いで前記の冷却条件に従って
徐冷することか必要である。In this way, from the initial molding temperature to 90℃ to 40℃
It is necessary to rapidly cool to a temperature between 1 and 2, followed by slow cooling according to the cooling conditions described above.

この場合でも冷却勾配が３時間未満になる条件を選ぶと
成形体の収縮が著しく、品質のすぐれた製品は得られな
い。Even in this case, if conditions are selected in which the cooling gradient is less than 3 hours, the molded product will shrink significantly and a product of excellent quality will not be obtained.

また、急冷の際成形体の温度を冷却しすぎて、徐冷開始
温度が４０℃よりも低（なると、続けて所定の冷却条件
に従って徐冷しても、すぐに発生している成形体の収縮
を回復させることはできない。In addition, if the temperature of the compact is cooled too much during rapid cooling, and the slow cooling start temperature is lower than 40°C, even if you continue slow cooling according to the predetermined cooling conditions, the temperature of the compact that has been generated immediately Contraction cannot be reversed.

他方、成形体の表面を約９０℃すなわち基材樹脂の軟化
温度よりも高い温度に長時間保持すると外力に対する抵
抗力が低下するため成形体の変形を生じやすくなり好ま
しくない。On the other hand, if the surface of the molded body is kept at about 90° C., that is, a temperature higher than the softening temperature of the base resin for a long period of time, the resistance to external forces will decrease, making the molded body more likely to deform, which is undesirable.

したがって、本発明における急冷後の徐冷開始温度は４
０℃から９０℃の間で選択することが必要である。Therefore, the slow cooling start temperature after rapid cooling in the present invention is 4
It is necessary to choose between 0°C and 90°C.

本発明における徐冷開始温度から室温すなわち徐冷終了
温度に至るまでの平均冷却速度は、０．０１〜０．３℃
／分の範囲内で選択されるが、高温側では冷却温度差を
小さくして多段階に区切って冷却し温度が下がるにつれ
て冷却温度差を大きくしながら冷却するのがよい。In the present invention, the average cooling rate from the slow cooling start temperature to room temperature, that is, the slow cooling end temperature is 0.01 to 0.3°C.
The temperature is preferably selected within the range of /min. On the high temperature side, it is preferable to reduce the cooling temperature difference and perform cooling in multiple stages, and as the temperature decreases, cooling is performed while increasing the cooling temperature difference.

本発明により、なんら発泡用ガスの遺漏なしに品質の良
好な発泡成形体が得られる理由は未だ解明されていない
が、おそら（次の理由によるものと思われる。Although the reason why a foam molded article of good quality can be obtained according to the present invention without any leakage of foaming gas has not yet been elucidated, it is probably due to the following reasons.

すなわち、本発明でみられる予備発泡粒子の型内発泡は
、予備発泡を終了した後に未だ残存するごく少量の発泡
ガス、及び（又は）予備発泡以降に大気から浸透した常
圧に近い気体の、熱膨張に基づく発泡力によるものと考
えられる。That is, the in-mold foaming of the pre-foamed particles seen in the present invention is caused by a very small amount of foaming gas that still remains after the pre-foaming and/or a gas near normal pressure that has permeated from the atmosphere after the pre-foaming. This is thought to be due to foaming power based on thermal expansion.

したがって、これを急冷すると気泡内のガスの体積が急
激に減少し、成形体の収縮をもたらすことになる。Therefore, when this is rapidly cooled, the volume of gas within the bubbles is rapidly reduced, resulting in shrinkage of the molded product.

しかしながら、この冷却過程において、冷却がまだ完了
していない成形体の収縮力や変形力に比べ大きい剛性力
を保つことができれば収縮や変形が起りにくくなるとと
もに大気からの気体の浸透が促進されていっそう収縮力
、変形力が削減されることになる。However, during this cooling process, if a rigidity force that is greater than the shrinkage force and deformation force of the molded body that has not yet been completely cooled can be maintained, shrinkage and deformation will be less likely to occur, and the penetration of gas from the atmosphere will be promoted. Contraction force and deformation force are further reduced.

そして、成形体の冷却がさらに進行すればその剛性力も
増加し、その段階での収縮や変形をそ止することになる
。As the molded body cools further, its rigidity also increases, preventing shrinkage and deformation at that stage.

したがって、このような冷却パターンを繰り返している
限り、発泡用ガスの遺漏のない予備発泡粒子を用いた場
合であっても芯部まで均一に発泡した良質の発泡成形体
が得られる。Therefore, as long as such a cooling pattern is repeated, even when pre-expanded particles without leakage of foaming gas are used, a high-quality foamed molded product that is uniformly foamed to the core can be obtained.

本発明においては、常温に至るまで上記の冷却パターン
を繰り返すが、ここでいう常温は夏期及び冬期において
当然異なってくる。In the present invention, the above-described cooling pattern is repeated until the temperature reaches room temperature, but the room temperature here naturally differs between summer and winter.

しかしながら、原則的に上記の冷却パターンに従う限り
、この程度の温度差は結果にほとんど影響を与えないの
で無視することができる。However, as long as the cooling pattern described above is followed in principle, temperature differences of this magnitude have little effect on the results and can be ignored.

徐冷に際しては大気圧下、減圧下など圧力条件には特に
制限はな（、通常の冷却手段を利用して容易に行うこと
ができるが、連続的に成形体を製造する工業的な生産工
程にあっては、例えばそれぞれの冷却温度に設定したド
ームを段階的に設けてそのドーム内に成形体が必要時間
滞留するようにドーム長及び（又は）、成形体の移動速
度を調節するようにすれば、自動連続的な徐冷が可能に
なり、たいへん便利である。There are no particular restrictions on the pressure conditions for slow cooling, such as atmospheric pressure or reduced pressure (although it can be easily carried out using ordinary cooling means, it is not suitable for industrial production processes that continuously produce molded bodies). For example, domes set to different cooling temperatures may be provided in stages, and the length of the dome and/or the moving speed of the compact may be adjusted so that the compact remains within the dome for the required time. This allows automatic continuous slow cooling, which is very convenient.

本発明でいう架橋したエチレン系合成樹脂の予備発泡粒
子とは、原料樹脂に高、中、低圧法ポリエチレン樹脂及
びエチレン−酢酸ビニル共重合体、エチレン−エチルア
クリレート共重合体、アイオノマー、あるいは上記エチ
レン系樹脂どうしの混合物、あるいは他樹脂との混合物
であってエチレン成分が全樹脂の５０モル％以上の樹脂
を用い、それを架橋度１０〜８０％になるように架橋し
かつ発泡倍率で１５〜３０倍に発泡させた状態の粒子を
いう。In the present invention, the crosslinked pre-expanded particles of ethylene-based synthetic resin refer to raw material resins containing high-, medium-, and low-pressure polyethylene resins, ethylene-vinyl acetate copolymers, ethylene-ethyl acrylate copolymers, ionomers, or the above-mentioned ethylene resins. A mixture of these resins or a mixture with other resins in which the ethylene component is 50 mol% or more of the total resin is used, and it is crosslinked to a degree of crosslinking of 10 to 80% and an expansion ratio of 15 to 80%. Refers to particles that have been expanded 30 times.

この場合、架橋は発泡に先行して行うことが望ましいが
、架橋と発泡をほぼ同時あるいは同じ工程内で実施した
り、発泡の後に架橋する方法を用いることもできる。In this case, it is desirable that the crosslinking be performed prior to the foaming, but it is also possible to perform the crosslinking and foaming almost simultaneously or in the same process, or to perform the crosslinking after the foaming.

これらの選択は、架橋方法や、強調したい工程の特徴に
応じて適宜選ふことかできる。These selections can be made as appropriate depending on the crosslinking method and the characteristics of the process to be emphasized.

架橋の手段としては例えば電離性放射線を樹脂又は発泡
樹脂に照射して均一に架橋させる方法や、ジクミルパー
オキサイド等の有機過酸化物架橋剤、及び多官性モノマ
ー等の架橋促進剤等を適量を樹脂中に含有、分散させ、
加熱して架橋する方法などが用いられる。Crosslinking methods include, for example, irradiating the resin or foamed resin with ionizing radiation to uniformly crosslink it, using an organic peroxide crosslinking agent such as dicumyl peroxide, and a crosslinking accelerator such as a polyfunctional monomer. Contain and disperse an appropriate amount in the resin,
A method of crosslinking by heating is used.

この場合の架橋度とは架橋粒子をトルエン中で９時間煮
沸し残留するゲルの分率を％で表わしたものをいう。The degree of crosslinking in this case refers to the percentage of gel remaining after crosslinked particles are boiled in toluene for 9 hours, expressed as a percentage.

次に発泡の方法には、押出機内で溶融状態にある樹脂内
に揮発性発泡剤を含有せしめこれを大気圧下に押出して
発泡させる方法や、樹脂の粒子に揮発性発泡剤を直接接
触させ樹脂内に発泡剤を含浸させた後加熱して発泡させ
る方法や、水性懸濁状態にある樹脂に揮発性発泡剤を接
触させ、樹脂中に発泡剤を含浸させた後加熱して発泡さ
せる方法などが用いられる。Next, foaming methods include adding a volatile foaming agent to the molten resin in an extruder and extruding it under atmospheric pressure to foam, or bringing the volatile foaming agent into direct contact with the resin particles. A method in which resin is impregnated with a foaming agent and then heated to foam, or a volatile foaming agent is brought into contact with the resin in an aqueous suspension, the resin is impregnated with the foaming agent, and then heated and foamed. etc. are used.

この発泡（予備発泡）工程に用いられる揮発性発泡剤に
は例えば（ノルマル又はイソ）ブタン、プロパンなどの
炭化水素や、ジクロロメタン、ジクロロジフロロメタン
、ジクロロテトラフルオロエタンのような沸点が常温以
下の・・ロゲン化炭化☆☆水素などが用いられる。Volatile blowing agents used in this foaming (pre-foaming) step include hydrocarbons such as (normal or iso)butane and propane, and those with boiling points below room temperature such as dichloromethane, dichlorodifluoromethane and dichlorotetrafluoroethane. ...Rogenated carbide☆☆hydrogen etc. are used.

これらは単独でも、また適宜混合して使用することもで
きる。These can be used alone or in an appropriate mixture.

また、含浸条件によっては、窒素、空気等の不活性ガス
を発泡剤として使用することも可能である。Furthermore, depending on the impregnation conditions, it is also possible to use an inert gas such as nitrogen or air as a blowing agent.

樹脂を予備発泡粒子にするための発泡に必要な発泡剤量
は、目標とする発泡倍率（１５〜３５倍）及び発泡剤の
種類によって変動するが、一般には、樹脂１００重量部
に対し、１０〜３５重量部程度が用いられ、樹脂中に含
有されている状態にあるときに公知の予備発泡機で適温
に加熱され発泡剤としての機能を発揮する。The amount of blowing agent required for foaming the resin into pre-expanded particles varies depending on the target expansion ratio (15 to 35 times) and the type of blowing agent, but in general, it is 10 parts by weight per 100 parts by weight of the resin. About 35 parts by weight is used, and when it is contained in the resin, it is heated to an appropriate temperature in a known pre-foaming machine and functions as a foaming agent.

予備発泡を終えた粒子の大きさは、直径で約２〜１５ｍ
ｍ８度のものが有効でその形状は真球形、球形、擬球形
、正方形、長方形、多面立方体のものが用いられるが、
本発明の場合は、発泡膨張力の余裕が少なく後述する成
形型内の充填密度が、優れた成形体を得るための要因に
なる場合があるので、最も望ましくは真球形の予備発泡
粒子を用い型内の充填度を６０％以上にすることを考慮
すべきである。The size of the particles after pre-foaming is approximately 2 to 15 m in diameter.
An 8 degree m angle is effective, and its shape can be true spherical, spherical, pseudospherical, square, rectangular, or polyhedral cube.
In the case of the present invention, it is most desirable to use perfectly spherical pre-expanded particles, since there is little margin for expansion expansion force and the packing density in the mold, which will be described later, may be a factor in obtaining an excellent molded product. Consideration should be given to a degree of filling in the mold of 60% or more.

ここでいう充填度とは、次式で定義される。The degree of filling here is defined by the following equation.

例えば、この充填度が６０％未満になると得られる成形
体を形式している粒子間に隙間が残ったりあるいは、徐
冷勾配を着るしく長くしなげればならなくなるなどの欠
点がある。For example, if the filling degree is less than 60%, there are disadvantages such as gaps remaining between the particles forming the resulting molded article or the slow cooling gradient having to be made too long.

逆に、大気圧より高いガス圧力で予備発泡粒子を、圧縮
しつつ型内に充填し充填度を８０〜１ｏ。Conversely, the pre-expanded particles are compressed and filled into the mold at a gas pressure higher than atmospheric pressure to a filling degree of 80 to 1°.

％にすることは、上記の欠屯を積極的に改良できるのみ
ならず得られる成形体の諸物性が優れる利点もあり有利
である。% is advantageous because not only can the above-mentioned defect be positively improved, but also the resulting molded product has excellent physical properties.

真球形の予備発泡粒子の製造は、一般には製造が困難と
されているが、本発明では、例えば原料樹脂のＭ、Ｉ
が３〜３５、さらに厳密には、４〜２５のものを選び、
これを通常の非真球形のペレットとし、炭酸マグネシウ
ムなどの無機塩が共存する水性懸濁液中でかくはん加熱
すると、真球形の樹脂粒子が容易に得られるので、これ
を応用すれば真球形の予備発泡粒子も容易に作成するこ
とができる。It is generally considered difficult to manufacture perfectly spherical pre-expanded particles, but in the present invention, for example, M, I
Choose between 3 and 35, more precisely between 4 and 25.
By turning this into normal non-spherical pellets and stirring and heating them in an aqueous suspension containing an inorganic salt such as magnesium carbonate, perfectly spherical resin particles can be easily obtained. Pre-expanded particles can also be easily created.

なお、本発明でいう発泡倍率は単位重量の発泡体が占め
る体積（ｃｃ ）を測定し得た体積と重量（Ｐ）との比
（すなわちＣＣ／７）をもって示す。Note that the expansion ratio in the present invention is expressed as the ratio of the volume (cc) occupied by a unit weight of the foam to the weight (P) (ie, CC/7).

予備発泡粒子は、ただちにあるいは貯蔵輸送等に要する
相当長時間経過した後に、型内に充填される。The pre-expanded particles are filled into the mold either immediately or after a considerable period of time required for storage and transportation.

そして公知り加熱手段で加熱され、前述の徐冷工程を経
て成形体になる。Then, it is heated by a known heating means and becomes a molded body through the above-mentioned slow cooling process.

この際、型としては、多数の／」呼りを有していて閉鎖
し得るが密閉し得ない形式の公知の金型を用いることが
必要である。In this case, it is necessary to use a known mold which has a large number of openings and which can be closed but not hermetically sealed.

また加熱の手段としては加熱した流体、特に水蒸気を用
いるのが熱効率上望ましい。Further, it is preferable to use a heated fluid, particularly water vapor, as a heating means in terms of thermal efficiency.

本発明における冷却及び徐冷は成形体を型から取出して
後及び（又は）取出さないで行うことができるこの場合
の選択は用いる型の有効利用、及び型の種類によって選
ばれるもので、例えば、スチレンビーズ発泡に用いられ
るような重厚な金型を用いるときは型から取出して冷却
及び徐冷を行う方が有効であるが、熱容量の小さい型、
例えば薄肉の金属板で作った金型の内のりに重厚な金型
と二重壁構造にしたものを用いれば、成形体を薄肉の金
型と共に取出し、実質的には薄肉の金型のまま、成形体
を冷却、徐冷することによって本発明の徐冷の効果を一
段と高めることができる。Cooling and slow cooling in the present invention can be carried out after and/or without taking out the molded article from the mold. In this case, the selection is made depending on the effective use of the mold used and the type of mold. For example, When using heavy molds such as those used for styrene bead foaming, it is more effective to remove the mold from the mold and cool and slowly cool it, but molds with small heat capacity,
For example, if you use a mold made of a thin metal plate with a heavy mold and a double wall structure inside, the molded body can be taken out together with the thin mold, and the mold will remain in the thin mold. The effect of the slow cooling of the present invention can be further enhanced by cooling and slow cooling the molded body.

また、急冷の手段としては、一般に発泡ビーズ成形の際
に行われる冷却水や圧縮空気による成形品表面部よりの
冷却が用いられ、徐冷の手段としては例えば恒温槽内に
おいて雰囲気温度を段階的に低下させつつ目的温度まで
到達させる等の方法がとられる。In addition, as a means of rapid cooling, cooling from the surface of the molded product using cooling water or compressed air, which is generally performed during foam bead molding, is used.As a means of slow cooling, for example, the atmospheric temperature is gradually lowered in a constant temperature bath. A method is used to reach the target temperature while lowering the temperature to a certain level.

離型時の温度に制約がある場合には、これらの手段を適
宜組合わせて用いることも可能である。If there is a restriction on the temperature during mold release, it is also possible to use an appropriate combination of these means.

なお、本発明においては、大気圧に近い内圧を有する、
換言すれば実質的に大気圧よりも大きい内圧を保有して
いない予備発泡粒子を成形体にすることができる技術を
完成したものであるから当然内圧が例えば１．２〜５．
０気圧（絶対）に高められている予備発泡粒子を本発明
の方法に利用することもできるし、他方内圧が大気圧以
上１．２気圧（絶対）未満の範囲の高圧側に調整された
予備発泡粒子を本発明の方法に利用するときは、肉厚の
成形体が成形しやすいとか、徐冷所要時間を短縮できる
といった別の利点が生じるので興味がある。In addition, in the present invention, having an internal pressure close to atmospheric pressure,
In other words, since we have completed a technology that allows pre-expanded particles that do not have an internal pressure substantially higher than atmospheric pressure to be made into a molded product, it is natural that the internal pressure is, for example, 1.2 to 5.
Pre-expanded particles that have been raised to 0 atm (absolute) can be used in the method of the present invention, while pre-expanded particles whose internal pressure is adjusted to a high pressure side in the range of atmospheric pressure or more and less than 1.2 atm (absolute) can be used in the method of the present invention. The use of expanded particles in the method of the present invention is interesting because other advantages arise, such as ease of molding into thick-walled molded bodies and the ability to shorten the time required for slow cooling.

しかしながら本発明で予備発泡粒子に発泡用ガスを退部
しなくても成形体が得られるようになったことは、当業
者にとっても驚異であり、画期的なものであるというべ
きである。However, in the present invention, it is surprising even to those skilled in the art that a molded article can be obtained without the need to withdraw the foaming gas from the pre-expanded particles, and it should be called an epoch-making development.

本発明は上述の構成をもつことにより、当該技術分野に
おいて必須の要件とされていた発泡剤ガスの遺漏工程が
省略化され、安価に優れた発泡成形体が提供できるばか
りでなく、不特定多数の成形業者が単に予備発泡粒子の
供給を受けるだけで、特別な保管設備及び発泡剤遺漏等
の設備を要せず、手軽に随時発泡成形ができるといった
卓越した効果を有する。By having the above-described structure, the present invention omits the step of leaking the blowing agent gas, which is an essential requirement in the technical field, and can not only provide an excellent foam molded product at low cost, but also The present invention has an outstanding effect in that a molding company can easily perform foam molding at any time by simply receiving a supply of pre-expanded particles without requiring any special storage equipment or equipment for leaking foaming agent.

次に実施例により本発明をさらに詳細に説明する。Next, the present invention will be explained in more detail with reference to Examples.

なお、各側におけるヒケの評価は、平坦面を形成するよ
うに設計された成形体の長さ１００ｍｍの面に直定規を
当て、その縁と成形体平面との間に生じた間隙の最大長
を求め、次の尺度で評価した。In addition, to evaluate sink marks on each side, apply a straightedge to a 100 mm long surface of a molded product designed to form a flat surface, and measure the maximum length of the gap between the edge and the flat surface of the molded product. was calculated and evaluated using the following scale.

実施例 １ 第１表に示すように、３種類の旭ダウ社製ポリエチレン
樹脂のおのおの１００重量部に対しジクミルパーオキサ
イド０．４重量部を混合し、これを押出機に供給して溶
融混練しジクミルパーオキサイドが分解しない温度下で
押出し切断して、直径１．２ｍｍ、長さ４ｍｒｎの架橋
性樹脂ペレットを作成した。Example 1 As shown in Table 1, 0.4 parts by weight of dicumyl peroxide was mixed with 100 parts by weight of each of three types of polyethylene resin manufactured by Asahi Dow, and this was fed to an extruder and melt-kneaded. A crosslinkable resin pellet having a diameter of 1.2 mm and a length of 4 mrn was prepared by extrusion cutting at a temperature at which dicumyl peroxide did not decompose.

このペレツ）１００重量部に対して炭酸マグネシウム１
．５重量部、水１５０重量部をそれぞれ用意してオート
クレーブに仕込み、１７０℃３０分間かくはんしながら
加熱し、冷却後取出し乾燥したところそれぞれ架橋度が
５２％、４８％、５１％である直径１．５山の真球状の
架橋樹脂粒子が得られた。1 part by weight of magnesium carbonate per 100 parts by weight of these pellets
．． 5 parts by weight and 150 parts by weight of water were prepared, charged into an autoclave, heated at 170°C for 30 minutes with stirring, taken out after cooling, and dried. The degree of crosslinking was 52%, 48%, and 51%, respectively. Five truly spherical crosslinked resin particles were obtained.

この架橋樹脂粒子を耐圧容器に入れ液体のジクロロジフ
ロロメタンと接触させつつｓｏ’ｃで１．０時間かくは
んしたのち冷却して取り出しただちにコンベア一式予備
発泡機に供給し、ｉｏｏ℃の水蒸気で加熱したところそ
れぞれの発泡倍率が２１ｃｃ／ｆ７．１９ＣＣ／Ｐ、２
０ＣＣ／？である３種類の予備発泡粒子が得られた。The cross-linked resin particles were placed in a pressure-resistant container, brought into contact with liquid dichlorodifluoromethane, stirred in SO'C for 1.0 hours, cooled, taken out, immediately fed to a pre-foaming machine with a conveyor, and heated with water vapor at 100°F. As a result, the foaming ratio of each was 21cc/f7.19CC/P, 2
0CC/? Three types of pre-expanded particles were obtained.

このようにして得た粒子について、公知の方法で内圧を
測定したところ、いずれも実質的にＯｋｇ／ｃｒＡ（ゲ
ージ圧）であり大気圧とほとんど同じであることが確認
された。When the internal pressure of the thus obtained particles was measured using a known method, it was confirmed that all of the particles were substantially O kg/crA (gauge pressure), which was almost the same as atmospheric pressure.

この発泡粒子をそれぞれ型内に充填度７０％に充填し、
元圧１．５ ｋｇ／ｃｒＡ （ゲージ圧）、加熱最終時
の圧力０．５ ｋｇ／ｌｙＡ （ゲージ圧）の水蒸気で
加熱戒形した。These foamed particles are each filled into a mold to a filling degree of 70%,
It was heated with steam at an original pressure of 1.5 kg/crA (gauge pressure) and a final pressure of 0.5 kg/lyA (gauge pressure).

この時に用いた成形機は、東洋機械金属社製ＥＣＨＯ−
１２０型であり、用いた金型は内容積で長さ３００ｍｍ
、巾１００ｍｍ、内厚み（最大３０〜最小２０ｍｍ）の
写真図のような形状を持ち壁部に多数の***を持つ閉鎖
型のものである。The molding machine used at this time was ECHO- manufactured by Toyo Kikai Kinzoku Co., Ltd.
120 type, and the mold used has an internal volume and length of 300 mm.
It is a closed type with a width of 100 mm, an inner thickness (maximum 30 to minimum 20 mm), and a shape as shown in the photograph, with many small holes in the wall.

この際の冷却パターンを第１図に示す。The cooling pattern at this time is shown in FIG.

これから明らかなように、Ｂは成形温度を高くしたため
に成形体の温度も高く、いったん、成形機内に存する金
型及び成形品に対して冷却水を吹きつげ成形品表面温度
を９０℃まで急冷した後、この成形品を金型に納めたま
まの状態で成形機より取り出し、雰囲気温度の調整が可
能な恒温室に入れ、■〜■の徐冷条件に従い約６時間余
の時間を要して冷却した。As is clear from this, in B, the temperature of the molded product was high due to the high molding temperature, and once cooling water was blown onto the mold and molded product in the molding machine, the surface temperature of the molded product was rapidly cooled to 90°C. After that, the molded product, still in the mold, was taken out of the molding machine and placed in a constant temperature room where the ambient temperature could be adjusted, and it was cooled for about 6 hours under the slow cooling conditions from ■ to ■. Cooled.

また、Ｃは同様にして成形後８０℃迄急冷しておいて■
〜■の徐冷条件に従い約５時間の時間を要して冷却した
。Similarly, for C, after molding, rapidly cool it to 80℃.
It took about 5 hours to cool down according to the slow cooling conditions of ~■.

さらにＡは同様にして急冷の程度を変更し、それぞれ■
〜■、■〜■、■〜■、■〜■の徐冷条件に従って冷却
したが、特に■〜Ｃ条件のものは、２５時間にも及び長
時間の冷却時間が必要であった。Furthermore, for A, the degree of rapid cooling was changed in the same way, and each
Cooling was carried out according to the slow cooling conditions of ~■, ■~■, ■~■, and ■~■, but especially those under conditions ■~C required a long cooling time of up to 25 hours.

しかしながら得られた成形体は剛性、弾性、気泡分布等
共に優れた発泡体でヒケと呼ばれる収縮現象も認められ
ない商品価値の高いものであった。However, the obtained molded product was a foamed product with excellent rigidity, elasticity, and cell distribution, and had high commercial value with no shrinkage phenomenon called sink marks.

■〜■の冷却パターンにより得られた製品の写真を第３
図に示す。The third photo of the product obtained by the cooling pattern of ■～■
As shown in the figure.

比較例 実施例１で用いたＡの予備発泡粒子を用い成形条件はそ
のままで冷却条件のみを第２図に示すプログラムすなわ
ち、０〜０、＠〜０．０〜０．０〜０に従って冷却させ
た。Comparative Example The pre-expanded particles of A used in Example 1 were used, and the molding conditions were the same, but only the cooling conditions were cooled according to the program shown in FIG. Ta.

得られた成形体はいずれも集綿が著しく商品価値のある
ものは得られなかった。All of the molded products obtained had remarkable cotton collection and were not of any commercial value.

０〜０の冷却パターンで得られた製品の写真を第４図に
示す。A photograph of the product obtained with the 0-0 cooling pattern is shown in FIG.

実施例 ２ 実施例１で用いたＢの発泡倍率１９ＣＣ／Ｐの予備発泡
粒子を耐圧容器に充てんし、８気圧の窒素ガスを充填し
て、予備発泡粒子内の気泡の内圧を１．３気圧にしたこ
の粒子を実施例１と同様に、第１図の冷却プログラム■
〜■に沿って加熱成形し冷却して成形体を得た。Example 2 The pre-expanded particles of B used in Example 1 with an expansion ratio of 19 CC/P were filled into a pressure-resistant container, and nitrogen gas of 8 atm was filled to reduce the internal pressure of the bubbles in the pre-expanded particles to 1.3 atm. As in Example 1, the particles were subjected to the cooling program ■ shown in Figure 1.
A molded article was obtained by hot molding and cooling in accordance with ~■.

この成形体は粒子間の接着に隙間がなく、肉の盛上りが
良好で、平滑な成形体であった。This molded product had no gaps in the adhesion between the particles, had good raised flesh, and was smooth.

【図面の簡単な説明】[Brief explanation of the drawing]

第１図は本発明の冷却勾配の１例を示す冷却パターン、
第２図は比較の冷却勾配の例を示す冷却パターンである
。 第３図は本発明の方法で得られた成形体を第４図は比較
の成形体をそれぞれ示す写真である。FIG. 1 shows a cooling pattern showing one example of the cooling gradient of the present invention.
FIG. 2 is a cooling pattern showing an example of a comparative cooling gradient. FIG. 3 is a photograph showing a molded article obtained by the method of the present invention, and FIG. 4 is a photograph showing a comparative molded article.

Claims (1)

【特許請求の範囲】[Claims] １ エチレン系合成樹脂発泡体粒子を閉鎖型に充填後こ
れを加熱することにより該粒子を膨張させて型に合致し
た成形体を得る方法において、架橋したエチレン系合成
樹脂から成り大気圧に近い内圧を有する予備発泡粒子を
非密閉性閉鎖型内に充填し、加熱して成形したのち、成
形体表面を９０〜４０℃の範囲内の温度まで急冷し、次
いで平均冷却速度０．０１〜０．３℃／分で、３時間以
上にわたって行う徐冷段階を経て室温まで冷却すること
を特徴とする架橋エチレン系樹脂発泡成形体の製造方法
。1 In a method of filling a closed mold with ethylene-based synthetic resin foam particles and then heating the particles to expand the particles to obtain a molded body that conforms to the mold, the foam is made of cross-linked ethylene-based synthetic resin and has an internal pressure close to atmospheric pressure. After filling the pre-expanded particles with a non-sealing closed mold and heating and molding, the surface of the molded product is rapidly cooled to a temperature within the range of 90 to 40°C, and then the average cooling rate is 0.01 to 0. A method for producing a crosslinked ethylene resin foam molded article, which comprises cooling to room temperature through an annealing step performed at 3° C./min for 3 hours or more.