JP3758116B2 - Open cell foam and method for producing the same - Google Patents
Open cell foam and method for producing the same Download PDFInfo
- Publication number
- JP3758116B2 JP3758116B2 JP18899898A JP18899898A JP3758116B2 JP 3758116 B2 JP3758116 B2 JP 3758116B2 JP 18899898 A JP18899898 A JP 18899898A JP 18899898 A JP18899898 A JP 18899898A JP 3758116 B2 JP3758116 B2 JP 3758116B2
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- Prior art keywords
- open
- cell foam
- ethylene
- weight
- propylene
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- Molding Of Porous Articles (AREA)
- Compositions Of Macromolecular Compounds (AREA)
- Processes Of Treating Macromolecular Substances (AREA)
- Manufacture Of Porous Articles, And Recovery And Treatment Of Waste Products (AREA)
- Heating, Cooling, Or Curing Plastics Or The Like In General (AREA)
- Extrusion Moulding Of Plastics Or The Like (AREA)
Description
【0001】
【発明の属する技術分野】
本発明は連続気泡発泡体およびその製造方法に関するものである。
【0002】
【従来の技術】
従来、連続気泡の高発泡スポンジを製造する方法として、あらかじめ押出加硫成形あるいは型加硫成形した独立気泡の発泡体を、通しロールなどにより圧力をかけて気泡を押しつぶし、気泡同士を連続化させることにより連続気泡の高発泡スポンジを製造する方法が知られている。
【0003】
【発明が解決しようとする課題】
しかしながら従来技術においては、コンパウンドの配合に当たって可塑剤を多量に配合するとともに、補強性のない充填材を配合するなど、コンパウンドの粘度を下げる必要があり、加工性および作業性が悪いという問題がある。また、一度発泡させたものをさらに通しロールなどにより圧力をかけて気泡を押しつぶさなければならないため工程が長くなり、経済的に不利である。本発明はこれらの問題点を克服した連続気泡の高発泡体およびその製造方法を提供することを目的とするものである。
【0004】
【課題を解決するための手段】
本発明者は上記の目的を達成するために鋭意検討の結果、ポリマーとして特定のポリマーブレンドを用い、かつ発泡剤を特定の割合で配合したコンパウンドを使用し、混練したコンパウンドをそのまま連続押出加硫成形法により成形することにより、比重が0.25以下の連続気泡の高発泡体が得られることを見出し、本発明を完成するに至った。
【0005】
すなわち本発明の比重が0.25以下の連続気泡の高発泡体は、ポリマーとしてエチレン−プロピレン−ジエン共重合体ゴム(以下、「EPDM」という。)とポリエチレン(以下、「PE」という。)とのポリマーブレンドを用い、かつEPDM100重量部に対して発泡剤20〜60重量部を配合したコンパウンドから連続押出加硫成形法により製造されたものである。
【発明の実施の形態】
【0006】
本発明のコンパウンドに使用するポリマーブレンドの一方の成分であるEPDMは、エチレン、プロピレンおよびジエン化合物からなる共重合体であり、ジエン化合物としては1,4−ヘキサジエン、ジシクロペンタジエン、エチリデンノルボルネンなどがある。EPDMとしてはムーニー粘度(ML1+4 ,100℃)が5〜50であるものを使用することが望ましい。その理由は、ムーニー粘度(ML1+4 ,100℃)が5未満では作業性および加工性に難があり、一方50を超えると気泡構造が独立気泡になりやすいからである。
【0007】
上記ポリマーブレンドの他方の成分としてPEを用いる理由は、PE無添加では気泡構造が独立気泡になりやすく、PEの添加により常温時のコンパウンド粘度は高いが、加硫発泡時の高温で粘度を下げることが可能であるからである。PEの種類としては、エチレンを高圧(500〜7000atm)で重合することにより得られる、密度が0.910〜0.935g/cm3 の低密度ポリエチレンを使用することが好ましい。
【0008】
EPDMとPEのポリマーブレンド(以下、「EPDM/PEブレンド」という。)におけるEPDMとPEとの重量比に特に制限はないが、一般的にはEPDM/PE=100/10〜30とすることが好ましい。
【0009】
本発明のコンパウンドには上記ポリマーブレンドのほか、発泡剤が配合される。発泡剤としては任意のものが使用でき、具体例としては重炭酸ナトリウム、炭酸ナトリウム、重炭酸アンモニウム、炭酸アンモニウムなどの無機発泡剤のほか、有機発泡剤としてジニトロソペンタメチレンテトラミンなどのニトロソ化合物、アゾジカルボンアミド、アゾジカルボン酸金属塩などのアゾ化合物、ベンゼンスルホニルヒドラジド、トルエンスルホニルヒドラジドなどのアジド化合物などを挙げることができる。
【0010】
発泡剤の配合量は、EPDM100重量部に対して20〜60重量部とすることが必要である。その理由は、20重量部未満では比重が高く、独立気泡になりやすいからであり、一方60重量部を超えるとガス抜けが先行して気泡が成長せず、高発泡になりにくいからである。
【0011】
上記コンパウンドには、EPDM/PEブレンドおよび発泡剤のほかに、必要に応じて発泡助剤、加硫剤、加硫促進剤、充填材、酸化防止剤、着色剤などの添加剤を適宜配合することができる。
【0012】
上記コンパウンドは、ムーニー粘度(Vm,125℃)が5〜30で、かつムーニースコーチ(t5)が2〜7分であるものが好ましい。その理由は、ムーニー粘度(Vm,125℃)が5未満では作業性および加工性に難があり、一方30を超えると気泡構造が独立気泡になりやすいからである。またムーニースコーチ(t5)が2分未満ではロール混練時などの作業時に初期加硫が生じて安定した品質を得ることが困難であり、一方7分を超えるとガス抜けが先行して気泡が成長せず、高発泡になりにくいからである。
【0013】
上記コンパウンドの連続押出加硫による成形に当たっては、加硫温度を150〜250℃の範囲に制御することが好ましい。
【0014】
【作用】
連続押出加硫成形と同時に、連続気泡が形成される。
【0015】
【実施例】
以下に実施例および比較例を挙げて、本発明をさらに詳しく説明する。
【0016】
(実施例1)
下記の配合割合の成分を混練して本発明のコンパウンドを調製した。このコンパウンドの未加硫物の物性は、ムーニー粘度(Vm,125℃)が12で、かつムーニースコーチ(t5)は4.4分であった。
【0017】
【0018】
上記コンパウンドを加硫温度230℃で連続押出加硫成形法により成形し、発泡体を得た。この発泡体は気泡構造が連続気泡であり、発泡倍率は23倍、比重は0.05であった。
【0019】
(実施例2)
発泡剤の配合量を50重量部に変えた以外は実施例1と同様にして発泡体を製造した。この発泡体は気泡構造が連続気泡であり、比重は0.09であった。
【0020】
(実施例3)
コンパウンドの未加硫物のムーニースコーチ(t5)を下記のように変化させて加硫系を変量させた以外は実施例1と同様にして発泡体を製造したところ、発泡体の気泡構造はいずれも連続気泡であり、比重は下記のように変化した。
【0021】
t5(分) 3.6 4.4 5.1 5.7 6.9
比重 0.06 0.05 0.05 0.17 0.25
【0022】
(実施例4)
加硫調整しながら温度を下記のように変化させた以外は実施例1と同様にして発泡体を製造したところ、発泡体の気泡構造はいずれも連続気泡であり、比重は下記のように変化した。
【0023】
加硫温度(℃) 150 180 200 220 250
比重 0.13 0.07 0.06 0.05 0.06
【0024】
(比較例)
ポリマーとしてEPDM/PEブレンドに代えてEPDMのみを用いた(すなわちPE無添加)以外は実施例1と同様にして発泡体を製造したところ、発泡体の気泡構造は独立気泡であり、比重は0.19であった。
【0025】
【発明の効果】
以上説明したように本発明によれば、比重が0.25以下の連続気泡の高発泡体を得ることができ、また連続押出加硫成形と同時に連続気泡が形成されるためコスト的にも有利であり、加工性および作業性にも優れている。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an open cell foam and a method for producing the same.
[0002]
[Prior art]
Conventionally, as a method for producing an open-celled high-foam sponge, a closed-cell foam that has been extrusion vulcanized or mold vulcanized in advance is crushed by applying pressure with a threading roll, etc., to make the bubbles continuous. Thus, a method for producing an open-celled highly foamed sponge is known.
[0003]
[Problems to be solved by the invention]
However, in the prior art, it is necessary to reduce the viscosity of the compound by blending a large amount of plasticizer and blending a non-reinforcing filler when blending the compound, resulting in poor workability and workability. . Moreover, since the foamed material must be further passed through to press the bubbles with a roll or the like to crush the bubbles, the process becomes long, which is economically disadvantageous. An object of the present invention is to provide a high-open-cell foam having overcome these problems and a method for producing the same.
[0004]
[Means for Solving the Problems]
As a result of intensive studies to achieve the above object, the present inventor used a specific polymer blend as a polymer and used a compound containing a foaming agent in a specific ratio, and the kneaded compound was continuously extruded and vulcanized as it was. By forming by a forming method, it was found that a high foamed body of open cells having a specific gravity of 0.25 or less was obtained, and the present invention was completed.
[0005]
That is, the open cell high foam of the present invention having a specific gravity of 0.25 or less is ethylene-propylene-diene copolymer rubber (hereinafter referred to as “EPDM”) and polyethylene (hereinafter referred to as “PE”) as polymers. And a compound prepared by blending 20 to 60 parts by weight of a foaming agent with respect to 100 parts by weight of EPDM by a continuous extrusion vulcanization molding method.
DETAILED DESCRIPTION OF THE INVENTION
[0006]
EPDM, which is one component of the polymer blend used in the compound of the present invention, is a copolymer composed of ethylene, propylene, and a diene compound. Examples of the diene compound include 1,4-hexadiene, dicyclopentadiene, and ethylidene norbornene. is there. It is desirable to use EPDM having a Mooney viscosity (ML1 + 4, 100 ° C.) of 5 to 50. The reason is that if the Mooney viscosity (ML1 + 4, 100 ° C.) is less than 5, workability and workability are difficult, while if it exceeds 50, the cell structure tends to become closed cells.
[0007]
The reason why PE is used as the other component of the polymer blend is that, without PE, the cell structure tends to become closed cells, and the addition of PE increases the compound viscosity at room temperature, but lowers the viscosity at high temperatures during vulcanization foaming. Because it is possible. As the kind of PE, it is preferable to use low density polyethylene having a density of 0.910 to 0.935 g / cm <3> obtained by polymerizing ethylene at a high pressure (500 to 7000 atm).
[0008]
The weight ratio of EPDM and PE in a polymer blend of EPDM and PE (hereinafter referred to as “EPDM / PE blend”) is not particularly limited, but in general, EPDM / PE = 100 / 10-30. preferable.
[0009]
In addition to the above polymer blend, a foaming agent is blended in the compound of the present invention. Any foaming agent can be used. Specific examples include inorganic foaming agents such as sodium bicarbonate, sodium carbonate, ammonium bicarbonate and ammonium carbonate, as well as nitroso compounds such as dinitrosopentamethylenetetramine as organic foaming agents, Examples thereof include azo compounds such as azodicarbonamide and azodicarboxylic acid metal salts, and azide compounds such as benzenesulfonyl hydrazide and toluenesulfonyl hydrazide.
[0010]
The blending amount of the foaming agent needs to be 20 to 60 parts by weight with respect to 100 parts by weight of EPDM. The reason is that if it is less than 20 parts by weight, the specific gravity is high and it tends to become closed cells. On the other hand, if it exceeds 60 parts by weight, the gas escapes first and bubbles do not grow, and it is difficult to achieve high foaming.
[0011]
In addition to the EPDM / PE blend and the foaming agent, additives such as a foaming aid, a vulcanizing agent, a vulcanization accelerator, a filler, an antioxidant, and a colorant are appropriately blended with the above compound. be able to.
[0012]
The compound preferably has a Mooney viscosity (Vm, 125 ° C.) of 5 to 30 and a Mooney scorch (t5) of 2 to 7 minutes. The reason is that if the Mooney viscosity (Vm, 125 ° C.) is less than 5, workability and workability are difficult, while if it exceeds 30, the cell structure tends to become closed cells. If Mooney scorch (t5) is less than 2 minutes, initial vulcanization occurs during operations such as roll kneading, and it is difficult to obtain stable quality. On the other hand, if it exceeds 7 minutes, outgassing precedes and bubbles grow. It is because it is hard to become high foaming.
[0013]
In forming the compound by continuous extrusion vulcanization, the vulcanization temperature is preferably controlled in the range of 150 to 250 ° C.
[0014]
[Action]
Simultaneously with continuous extrusion vulcanization, open cells are formed.
[0015]
【Example】
Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples.
[0016]
Example 1
The compound of the present invention was prepared by kneading the following blending ratio components. As for the physical properties of the unvulcanized product of this compound, Mooney viscosity (Vm, 125 ° C.) was 12, and Mooney scorch (t5) was 4.4 minutes.
[0017]
[0018]
The compound was molded by a continuous extrusion vulcanization molding method at a vulcanization temperature of 230 ° C. to obtain a foam. This foam had a cell structure of open cells, the expansion ratio was 23 times, and the specific gravity was 0.05.
[0019]
(Example 2)
A foam was produced in the same manner as in Example 1 except that the blending amount of the foaming agent was changed to 50 parts by weight. This foam had an open cell structure and a specific gravity of 0.09.
[0020]
Example 3
A foam was produced in the same manner as in Example 1 except that the unvulcanized Mooney scorch (t5) of the compound was changed as follows to change the vulcanization system. Was also an open cell, and the specific gravity changed as follows.
[0021]
t5 (minutes) 3.6 4.4 5.1 5.7 6.9
Specific gravity 0.06 0.05 0.05 0.05 0.17 0.25
[0022]
(Example 4)
Except that the temperature was changed as follows while adjusting the vulcanization, a foam was produced in the same manner as in Example 1. As a result, the foam structure of the foam was open cell, and the specific gravity changed as follows. did.
[0023]
Vulcanization temperature (° C) 150 180 200 220 250
Specific gravity 0.13 0.07 0.06 0.05 0.06
[0024]
(Comparative example)
A foam was produced in the same manner as in Example 1 except that only EPDM was used in place of the EPDM / PE blend as the polymer (ie, no PE was added). The foam structure of the foam was closed cells, and the specific gravity was 0. .19.
[0025]
【The invention's effect】
As described above, according to the present invention, it is possible to obtain an open cell high foam having a specific gravity of 0.25 or less, and open cells are formed simultaneously with continuous extrusion vulcanization, which is advantageous in terms of cost. And excellent in workability and workability.
Claims (5)
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP18899898A JP3758116B2 (en) | 1998-07-03 | 1998-07-03 | Open cell foam and method for producing the same |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP18899898A JP3758116B2 (en) | 1998-07-03 | 1998-07-03 | Open cell foam and method for producing the same |
Publications (2)
Publication Number | Publication Date |
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JP2000017094A JP2000017094A (en) | 2000-01-18 |
JP3758116B2 true JP3758116B2 (en) | 2006-03-22 |
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Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
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JP18899898A Expired - Fee Related JP3758116B2 (en) | 1998-07-03 | 1998-07-03 | Open cell foam and method for producing the same |
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JP (1) | JP3758116B2 (en) |
Families Citing this family (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP4667660B2 (en) * | 2001-06-29 | 2011-04-13 | 三井化学株式会社 | Vulcanizable rubber composition |
JP4808502B2 (en) * | 2006-02-01 | 2011-11-02 | 三和化工株式会社 | EPDM open cell body and method for producing the same |
JP5349994B2 (en) * | 2009-02-09 | 2013-11-20 | 三和化工株式会社 | Cosmetic foam and method for producing the same |
-
1998
- 1998-07-03 JP JP18899898A patent/JP3758116B2/en not_active Expired - Fee Related
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JP2000017094A (en) | 2000-01-18 |
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