JPS6289738A - Ethylenic resin composition for open-cell foam - Google Patents

Abstract

PURPOSE:The titled composition that is obtained by adding a specific silicone oil and a foaming agent, thus giving foamed products with uniform fine cells despite no additional process of breaking foams under pressure, having good air permeability, water absorption, weather resistance and touch. CONSTITUTION:The objective composition is obtained by adding 1-30pts.wt. of a foaming agent and 0.1-5pts.wt. of a silicone oil represented by R3SiO-(R2 SiO)n-SiR3 (R is alkyl, phenyl, H; n is 1-10,000) to 100pts.wt. of an ethylenic resin. The silicone oil preferably has 100-1,000 as n in the formula.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a composition based on ethylene resin for producing open-cell foam in a single step. More specifically, the present invention relates to a composition for producing an open-cell foam in a single step, comprising an ethylene resin, a blowing agent, and a silicone oil.

The object of the present invention is to provide a composition for ethylene resin open-cell foam that has good air permeability, water absorption, and weather resistance. Because it is a cellular foam, it is more flexible than a closed cell foam, and has a superior texture and feel.The manufacturing method is characterized by:
An open-cell foam can be obtained by a one-stage heating method, and there is no need for a process of bursting the foam by applying pressure. This foam is used as a cushioning material, a heat insulating material, a sound absorbing material, or a p-material for cushions, pillows, mats, winter clothing, carpet linings, balls, toys, supporters, filters, etc.

Currently, foams made of ethylene resin are used as insulation materials, packaging materials,
Although they are used in large quantities as cushioning materials, most of them are closed-cell foams and are not used for applications that require water absorption, breathability, etc. Although some open-cell foams with air permeability can be found, they are limited to those with large cell diameters, rough texture, poor texture, and low commercial value. On the other hand, rubber or polyurethane open-cell foams are rapidly degraded by ultraviolet rays or ozone.

Conventional open-cell foams made of ethylene resin are produced by first producing closed-cell foams and then heating and expanding them. It has no elasticity, it is difficult to break the bubbles uniformly, and the bubble diameter is large. In order to solve this problem, a method was developed in which closed cells were first molded and then broken by pressure, but the process was two-step, the resulting foam was thinner, and the cells became open. However, the bubble membranes overlap and cannot be said to have good water absorption or air permeability. To improve this, Japanese Patent Publication No. 47-31695 proposes a method in which the closed-cell foam is first cooled to a temperature near or below the glass transition temperature, and then compressed to destroy the cell membrane. Although this method has been proposed, in the case of polyethylene, it is necessary to cool it with an expensive refrigerant such as liquid nitrogen, and the equipment becomes expensive.

On the other hand, Japanese Patent Publication No. 55-42100 proposed a one-step pressurizing and hot pressing method in which a fairly large amount of amorphous polypropylene was mixed with polyethylene together with a crosslinking agent as a method for obtaining an open-cell polyethylene foam in a one-step process. However, in this method, it is said that it is preferable to mix 30 to 50% by weight of amorphous polypropylene, and if it is less than 20% by weight, the open cell ratio will be low. Amorphous polypropylene is a by-product during the production of crystalline polypropylene, and it has no use value and has been discarded, so it makes sense to utilize it, but - universally shaped polypropylene is sticky even at room temperature. It is a clay-like substance that uses the properties of clay, and it is difficult to obtain molded products by itself, and it has traditionally been added in small amounts as an extender to low-cost foams, as disclosed in this patent. Mixing in large quantities will adversely affect the mechanical properties and feel of the foam.

The technical content of Japanese Patent Publication No. 54-63172 is to disperse and mix 30 to 300 parts by weight of inorganic powder with 100 parts by weight of polyolefin resin, foam it to form a closed-cell foam, and then deform it to break the foam. It is characterized by

Moreover, in this method, it is said that the communication of air bubbles is made even more effective by subjecting the inorganic powder to a surface treatment that actively reduces the adhesive force between the inorganic material interface and the polymer. In other words, this foam requires mixing a large amount of inorganic material simply to break the foam.

It is easy to imagine that the presence of the inorganic material causes the mechanical properties and tactile sensation of the foam to differ from those of the original polyethylene foam. More importantly, it shows how difficult it is to produce open-cell foams from polyolefins.

The inventors of the present application have conducted intensive studies to solve the many problems contained in these prior art technologies, and have found that (a) a single process as simple as possible, in other words, a separate process for breaking the bubbles; Developed a method for producing open-cell ethylene resin foam that has excellent water absorption, weather resistance, and texture without losing the characteristics of the ethylene resin itself due to large amounts of additives. It is characterized by the fact that by adding a small amount of silicone oil, the diameter of the bubbles before and after breaking can be made fine and highly uniform. 2) For this reason, it is possible to produce not only a batch method in a heating furnace but also an endless method, and e) the composition before foaming can be made into pellets,
The shape is not limited to powder, film, sheet, etc.

That is, in the present invention, 100 parts by weight of ethylene resin, 1 to 10 parts by weight of blowing agent,
% ('However, R is a group selected from an alkyl group, a phenyl group, and hydrogen, and even if all R's are the same group, some R may be another group, n is 1 to 10,
It is an integer of 000. ) silicone oil (l
The present invention relates to an ethylene resin open-cell foam composition having uniform and fine cells, characterized in that 1 to 5 parts by weight of 1L is added.

These features of the present invention will be specifically explained below. The form of the foaming composition does not matter, simply pellets,
It is possible to obtain open-cell foams from powders, films, and sheets, and furthermore, it is also possible to form them continuously on-line. For example, to obtain a thin foam sheet, it can be manufactured by forming it into a thin film and passing it through a heating furnace, and in the case of a thick sheet, it can be manufactured by passing pellets spread in a single layer through a heating furnace. It is also possible to do this, and the productivity can be increased compared to the conventional method of once producing a bulk foam and slicing it. Of course, even if an extruder, Ni-Goo, or other mixing method is used to obtain these compositions, the temperature must be such that the blowing agent does not substantially decompose.

It is also possible to use powdered ethylene resin and mix other additive components in powdered or liquid form to obtain a powdered composition, which is then heated to form an open-cell foam. can.

The foam obtained by this invention has a fine and uniform foam structure. Once this forms closed cells,
It is known that even with many conventional methods for breaking these bubbles, when the cells are closed, fine cells do not become uniform, fine, open cells at the stage of cell breaking. Only a foam containing air cells is obtained. For example, as shown in Example 1, the average bubble diameter is 100 to 2.
It has been impossible to obtain open-cell bodies consisting of microscopic cells of 00 μm size using conventional methods.

One of the features of the present invention is that it provides a weather resistant ft'L foam. For example, even if it is left outdoors for 6 months, it will not change color or deteriorate.

In the present invention, the ethylene resin is a polymer whose main component is ethylene, and includes high-pressure polyethylene, low-pressure low-density polyethylene, and kneaded low-density polyethylene (LLDPE).
), ethylene-vinyl ester copolymer, ethylene-
Refers to alkyl acrylate copolymers, ethylene-propylene copolymers, ethylene-α/olefin copolymers, and others.

The foaming agent used in the present invention has a foaming temperature of 90°
C or higher is desirable. The decomposition temperature can also be adjusted by using a promoter or an auxiliary agent.

Examples include:

Azobisisobutyronitrile, diazocarbonamide (
(with auxiliary agent), P-) luenesulfonyl hydrazide (with auxiliary agent), 44 +-oxybis(benzenesulfonyl hydrazide) (with auxiliary agent), n-hebutane, n-octane, n
-nonane, n-decane.

The silicone oil used in the present invention has the general formula RI 5i
O-(R,SiO)n-8iRm, where R is a group selected from an alkyl group, a phenyl group, and hydrogen, and all R are the same-
group, or some R's may be different groups.

In the above, n is 1 to 10,000, and 100 to
t000 is preferred.

The ratio of each component of the foamable composition of the present invention is shown below.

The blowing agent is 1 to 3 parts by weight per 100 parts by weight of ethylene resin.
ON amount part is required.

If the amount is less than 1 part by weight, there is almost no foaming effect, and if it is more than 3 parts by weight, the amount of decomposed products of the blowing agent that wastefully escapes into the atmosphere during foaming increases, resulting in poor efficiency.

The amount of silicone oil required is Q, 1 to Stt parts. 0
．． If it is less than 1 part by weight, it will not have the effect of providing bubbles with a uniform fine structure, and if it is more than 5 parts by weight, oozing will be noticeable.
Adversely affects the physical properties of the foam.

In the present invention, the composition must contain oxidation stabilizers, ultraviolet stabilizers, inorganic photonic agents, pigments, flame retardants, plasticizers, other additives, other waxes, rubbers, etc. can.

In the present invention, the temperature at which the composition is heated is higher than the temperature required for foaming, and specifically is between about 120 and 250°C.

In the present invention, the foam is cooled after heating.
The structure is fixed.

The cooling temperature is desirably 50°C or less.

Heating methods include heating gas such as electricity, direct or indirect contact with heated metals such as iron or aluminum, external heating using infrared rays, burners, electric heat, etc., as well as internal heating such as high frequency heating. .

Furthermore, depending on the purpose, heating can be performed under normal pressure or under increased pressure. Examples are given below.

Example 1 Ethylene-vinyl acetate copolymer with a melt index of 20 and a vinyl acetate component of 28 polymers (Nippon Unicar fi) 1
00 parts, 10 parts of azodicarbonamide "Celmic CAP149J (foaming temperature 125°C; manufactured by Sankyo Kasei), which contains an auxiliary agent, NUC-silicone oil L-45 (methyl silicone oil manufactured by Nippon Unicar; 10.0OOC8;
n=750) was kneaded in a Banbury mixer at 80° C. for 5 minutes, and then pelletized. The pellets were compression-molded into a sheet with a thickness of 1 nm, placed on a polyester film, placed on an aluminum plate, heated in an open air at 1900 C for 4 minutes, then taken out and allowed to cool.

The obtained foam has a thickness of 7 m, most of which consists of cells with a cell diameter of 100 to 200 μρ, and an apparent density of 0.
It was an open-cell foam with a diameter of 1097 cm.The maximum water absorption amount was 0.739 parts cm.

Comparative Example 1 A foam obtained in the same manner as in Example 1 without using silicone oil had a thickness of 7 fm, rough cells with a cell diameter of 1 to 3 S, and an apparent density of 0.11. /i/crIL”
It was an open cell foam. Maximum water absorption is 0.66E
/cm” and ivy.

Example 2 Melt index 20, ethyl acrylate component 20
NH% of ethylene-ethyl acrylate copolymer (Nippon Unicar 1F!Ioo part), Azocica-bonamide foaming agent [Celmic CAP124J (foaming temperature 13
0°C; Sankyo Kasei) 5 parts, NUC-silicone oil L-45 (Nippon Unicar methyl silicone oil; t
ooocs; n=244) was kneaded in a Banbury mixer at 80° C. for 5 minutes, and then pelletized. The pellets were compression molded into a sheet with a thickness of 2 mm. This sheet was placed on an aluminum plate and heated in an open air at 190°C for 5 minutes, then taken out and left to cool. The obtained foam is 6-5 m thick, consists of cells with a cell diameter of 100-250 μe, and has an apparent density of 11221! /am” continuous energy +!2
It was a molded foam. The maximum water absorption amount was α23y/α1.

Example 3 Melt index α4, density i [L894 ethylene-
To 100 parts of α-olefin copolymer DFDA-1138 (Union Carbide fi), Azocica-bonamide foaming agent [Celgaik CAP501] J (foaming temperature 15
0°C; manufactured by Sankyo Kasei) 10 sound Is, NUC-silicone oil L-45 (methyl silicone oil manufactured by Nippon Unicar;
1000C8; n=244) was kneaded in a Banbury mixer at 125°C for 10 minutes, and then pelletized. The pellets were compression-molded into a sheet with a thickness of 2 mm, placed on an aluminum plate, heated in a Matsufuru furnace at 20° C. for 5 minutes, and then taken out and allowed to cool.

The obtained foam was easily peeled off from the aluminum plate. This foam had a thickness of 8 mm, consisted of cells with a cell diameter of 100 to 300 μm, and had an apparent open-cell foam with a density of 0.2597α1. The maximum water absorption amount was Q, 3411/cm''.

Example 4 A foam was obtained in the same manner as in Example 3, using polyethylene DNDJ-040sR (Nippon Unicar) having a melt index of 25 and a density of α9145 instead of DFDA-1138. This foam has a float of 8m11. Bubble diameter 150~SOOμg, apparent density [L 26 g/l”
It was an open cell foam.

The maximum water absorption amount was 0.521/■1.

Name of agent: Motohiro Kurauchi l)゛・-该L1 Relationship to the famous case for which the procedure sleeve is amended on February 4, 1986 Patent i1 Name of applicant Nippon Unicar Co., Ltd.

Claims (1)

[Scope of Claims] A foamable composition comprising 100 parts by weight of an ethylene resin and 1 to 30 parts by weight of a blowing agent has the general formula R_3SiO-(R_2SiO_n-SiR_3 (where R is an alkyl group, a phenyl group, and hydrogen). It is a selected group, and all R's may be the same group or some R's may be different groups, and n is 1 to 10,000.
is an integer. ) silicone oil 0.1-5
1. An open-cell ethylene resin foam composition having uniform and fine cells, characterized in that the composition contains parts by weight.