JPS61213128A - Adhesive method of crosslinked polyolefin article - Google Patents

Abstract

PURPOSE:To offer a method of adhering favorably crosslinked polyolefin articles to each other or that of adhering favorably a polyolefin article which is not crosslinked and the crosslinked polyolefin article to each other, by a method wherein a foamed layer is provided on the surface of an article to be stuck and adhesive treatment is performed on the foam layer. CONSTITUTION:As for a foam of a foamed layer in a surface layer, it is desirable that it is an open cell and when a cell wall is thick, the foam, for example, is kept collapsed with a gold brush. As for the foamed layer, it is obtained by foaming alpha olefin, for example, a homopolymer and copolymer group such as ethylene, propylene, 1-butene, 4-methylpentene-1, the homopolymer and copolymer group of the alpha olefin containing halogen or carbonic acid or its dervative or the polyolefin such as the copolymer group of the alpha olefin and the carbonic acid or its derivative and a crosslinked material of those by making use of a chemical foaming agent and physical foaming agent. As for loadings of a foaming agent, an extent of 0.5-15wt part is appropriate.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for bonding polyolefin articles, such as crosslinked polyolefin pipes, in which one or both of the articles to be bonded have at least a surface layer of crosslinked polyolefin.

[Prior art]

Articles made of non-crosslinked polyolefins can be fused to each other, but if at least one of the articles to be joined is made of a crosslinked polyolefin, the crosslinked polyolefin does not substantially melt and cannot be fused well.

Pipes made of cross-linked polyolefin are superior in heat resistance, mechanical strength, and especially resistance to environmental stress cracking compared to pipes made of non-cross-linked polyolefin, so they are used as gas pipes, water pipes, or hot water pipes. Although it is seen as promising, it has the drawback that it cannot be connected by fusion bonding for the reasons mentioned above. Furthermore, even when an adhesive is used, a specific adhesive is used to heat crosslink, and an adhesive method that allows room temperature bonding is long awaited.

Recently, water-crosslinkable polyolefin pipes have been proposed that are uncrosslinked when the pipes are connected, allowing fusion splicing, and that are crosslinked by moisture in the atmosphere after the pipes are connected. However, in many cases, the surface layer of the pipe is crosslinked due to moisture in the atmosphere during storage, resulting in a problem that the fusion splicability is reduced.

[Problem that the invention seeks to solve]

The present invention provides crosslinked polyolefin articles such as pipes,
The object of the present invention is to provide a method for excellently adhering sheets to each other, or to bonding non-crosslinked polyolefin articles and crosslinked polyolefin articles. In particular, the present invention provides an adhesion method in which the above-mentioned adhesion can also be performed by an adhesion treatment at room temperature.

[Means for solving problems]

In the bonding of polyolefin articles in which one or both of the articles to be bonded have at least a surface layer made of crosslinked polyolefin, the present invention provides a foam layer on the surface of the bonded articles, and performs the bonding treatment using the foam layer. The present invention relates to a method for adhering polyolefin articles, characterized in that:

In the following description, the concept of a crosslinked polyolefin article is not limited to one in which the entire article is made of crosslinked polyolefin, but also includes one in which at least the surface or the vicinity of the area where adhesion is required is made of crosslinked polyolefin.

The bonding method according to the present invention does not require any special operation, but by interposing the adhesive between the objects to be bonded and applying pressure for an appropriate time, the adhesive fills into the bubbles.
It is cured and a strong adhesion is achieved due to its anchoring effect.

Therefore, it is preferable that the cells in the foam layer in the surface layer are open cells. Even in the case of closed cells, if the cell walls are thin, there is no particular problem because the adhesive will penetrate. If it is thick, it is preferable to destroy the air bubbles using a gold brush, for example.

In the present invention, Method B of providing a foam layer on the surface of the article to be bonded includes, for example, a method in which the surface of the crosslinked polyolefin article itself is a foam layer, and a method in which a new crosslinked or non-crosslinked foam layer is formed on the surface of the crosslinked polyolefin article. A method of providing the information is exemplified.

In this case, the foam layer may be an α-olefin, such as ethylene, propylene, butene-L4-methylpentene-1
Polyolefins such as homopolymers and copolymers of α-olefins containing halogens, carboxylic acids or derivatives thereof, or copolymers of α-olefins with carboxylic acids or derivatives thereof, and crosslinked products thereof are conventionally used. Known chemical blowing agents (e.g.
Azodicarbonamide, azobisisobutyronitrile,
Foamed using organic blowing agents such as dinitropentamethylenetetramine and valatoluenesulfonylhydrazine, inorganic blowing agents such as sodium bicarbonate) and physical blowing agents (e.g. nitrogen gas, propane gas, freon gas, argon) can be given. The amount of foaming agent added was 0.
Approximately 5 to 15 parts by weight is appropriate.

In the present invention, examples of methods for providing a foam layer on the crosslinked polyolefin surface layer include the following methods.

(Method 1) A method in which a surface layer consisting of a foam layer is coextruded with a polyolefin layer.

That is, for example, using an apparatus in which two extruders are connected to one head, an article to be bonded from the - extruder, a crosslinked or non-crosslinked polyolefin composition that can be foamed from the second extruder (the blowing agent is , a chemical blowing agent such as the one described above is used) is extruded into a concentric cylindrical shape or a two-layered plate shape,
A method of foaming the discharge die at the tip of the head at a temperature higher than the decomposition temperature of the chemical foaming agent.

(Method 2) A method of injecting a blowing agent into the surface layer of a crosslinkable crosslinked polyolefin resin during extrusion.

That is, for example, in a method of forming a foam layer using one extruder, the above-mentioned physical foaming agent is injected under pressure from a part of the extrusion screw or the outside of the head, and after exiting the head, it is released to normal pressure. A method of foaming.

The adhesive used in the present invention is not particularly limited as long as it has the adhesive strength used for bonding non-crosslinked polyolefins, such as polyurethane adhesives, epoxy adhesives, etc. Examples include adhesives and silicone adhesives that cure at room temperature.

Crosslinked polyolefin articles that can be connected in the present invention include α-olefins, such as homopolymers and copolymers such as ethylene, propylene, butene-1,4-methylpentene-1, halogens, carboxylic acids, or derivatives thereof. Homopolymers and copolymers of α-olefins, or crosslinked copolymers of α-olefins with carboxylic acids or derivatives thereof, such as cross-linked polyethylene, cross-linked polypropylene, cross-linked polybutene-1, cross-linked poly-4-methylpentene-11, cross-linked ethylene- Propylene copolymer, crosslinked ethylene-vinyl acetate copolymer,
Examples include those made of crosslinked ethylene-ethyl acrylate copolymer and crosslinked chlorinated polyethylene. The degree of crosslinking of the polyolefin constituting the article is 90 in terms of gel fraction.
- 100% (wt%; hereinafter, in the description of the present invention, unless otherwise specified, all % and parts shall mean wt% and parts by weight.) may be highly crosslinked,
It may have a low to moderate degree of crosslinking of 90% or less, for example 10 to 90%. These crosslinked polyolefin articles are extrusion heat crosslinked using, for example, polyolefin compositions that include an organic peroxide. A water-crosslinkable polyolefin composition is extruded and then crosslinked with water, or a polyolefin composition containing a sensitive substance sensitive to radiation or ultraviolet rays is extruded and crosslinked by irradiation with radiation or ultraviolet rays. It can be produced by a known method such as, and in the present invention, products produced by any crosslinking method can be used. Particularly preferred are molded articles, especially pipes, made of crosslinked polyethylene having a gel fraction of at least 10%, especially at least 20%, crosslinked by heat crosslinking using organic peroxides or by water crosslinking.

According to the method of the invention, crosslinked polyolefin articles, such as pipes, ronds, and sheets, or non-crosslinked polyolefin articles and crosslinked polyolefin articles can be bonded well. In particular, according to the present invention, bonding of pipes that requires strong adhesion (for example, bonding between pipes, bonding between pipes and joints) can be effectively performed.

[Action/Effect]

According to the present invention, the adhesive is filled into the cells of the surface layer of the crosslinked polyolefin article, which creates an anchoring effect and achieves strong adhesion even when using a cold-adhesive adhesive.

〔Example〕

Examples 1 to 4 and Comparative Examples 1 to 2 Adheres A and B listed in Table 1 were adhered at the dosages listed in Table 1, and the adhesive strength was examined and shown in Table 1. .

The bonding conditions were as follows.

Example 1: Temperature---20℃ Time - 24 hours Insert the pipe into the socket and glue it Example 2: Same as Example 1 Example 3: Temperature---20℃ Pressure-・-・・-0.1kg/cd Time...--24 hours Layer the sheets and apply pressure to adhere them. Example 4: Same as Example 3 Comparative Example 1: Same as Example 1 Comparative Example 2: Same as Example 3 The shape and material of the foam layer are as follows.

(Shape) Example 1: The outermost layer 1III11 thickness of adherend A and the outermost layer lll11 thickness of adherend B were foamed by coextrusion.

Example 2: Same as Example 1 Example 3: The outermost layer of adherend A has a thickness of 0.5fi and
.

The outermost layer Q of adherend B was foamed to a thickness of 5 am using the injection method.

Example 4: The coated surfaces of adherend A and adherend B were each coated at 0.
Coextruded and foamed in 25m5.

Comparative Examples 1 and 2: None (material) Example 1: Same material as adherends A and B, respectively 112.2 parts Azodicarbonamide 2.5 parts Example 2: Same as Example 1 Example 3: Adhered Same material as body A and B respectively 115 part C
CI Fz-CCj! Fz 10 parts Example 4: Same material as adherends A and B 102 parts Azodicarbonamide 3.0 parts Comparative Examples 1 and 2:
The unadhesive strength was determined as follows.

(I method): 50cm on both ends with the socket joint part in the center
A water pressure test sample having a pipe of 100 mL was prepared, and the internal pressure of the pipe was increased at a rate of 5 kg/min to destroy the test sample.

(■ method): Tensile shear adhesive strength JIS K6850),
However, overlap width: 10m + w, length: 30III11° (margin below) (Notes in Table 1) °1: High-density polyethylene 100 parts ρ
(Density) 0.945g/c+J old (Melt Indafukus) 0.8g/10min Dicumyl peroxide 2.2 parts″2: High density polyethylene
100 parts (ρ and old are the same as adherend A) Vinyltrimethoxysilane 2.0 parts Dicumyl peroxide 0.2 parts Di-butyl-tin-dilaurate 0.05 parts 1: Medium density polyethylene
, 100 parts ρ 0.935 g/cd Ml 005 g/10 min Vinyltrimethoxysilane 2.0 parts Dicumyl peroxide 0.2 parts Di-butyl-tin-dilaurate 0.05 parts 84: Polypropylene
100 parts ρ 0.91 g / d T 0.5 g / 10 minutes 3-trimethoxysilylpropyl azide formate 3 parts dicumyl peroxide 0.2 parts di-butyl-tin-dilaurate 0.05 parts"S: chlorinated polyethylene
100 parts Specific gravity 1.15 Old 0.4 g / 10 minutes Chlorine content 32% Antimony dioxide 10 parts Dibasic lead sulfate 1.5 parts Dicumyl peroxide 3.5 parts "&: Ethylene-vinyl acetate copolymer Combined ρ 0.93 g/aJ Old 0.8 g/10 min Vinyl acetate content 15% m?: Modified polyethylene grafted with maleic acid 50 parts Maleic acid content 0.2% ρ 0.93 g/d Ml 4 g/10 Ethylene-ethyl acrylate copolymer 50 parts Ethyl acrylate content 0.4% ρ 0.93 g/c+J Gate 1 1.5 g/10 minutes 08: Ethylene-vinyl acetate copolymer 100 parts Vinyl acetate content 15% ρ 0.93g/d Ml 3g/10min Dicumyl peroxide 2.0 parts 0: Room temperature curing two-component epoxy adhesive; Aica Aibo 7EX58
2C, A / B = 2 / 1 (trade name of Aikanigyo Co., Ltd.) 11f': Room temperature curing flexible epoxy adhesive; Epicor) 828 (trade name of Shell Co., Ltd.) 100 parts by weight and AE
Mixture of 58 parts by weight of R-H-L-220 (trade name of 11!L Kasei Co., Ltd.) 1 day: Room temperature curing urethane adhesive; Unibon 800
0. Main agent/curing agent-1/1 (Sanyo Chemical Co., Ltd. product name) Umbrella 12. Two-component silicone adhesive that cures at room temperature; K
F, 6 T RT V (F'M Chemicals Product Name II, State of Destruction A: Peeling from the adhesive surface B: Destruction of the test piece material (adherent) C: Destruction of the adhesive layer D: Adhesive part water leakage from

Claims (1)

[Claims] When adhering polyolefin articles in which one or both of the articles to be adhered has at least a surface layer made of crosslinked polyolefin, a foam layer is provided on the surface of the article to be adhered, and the adhesive treatment is performed using the foam layer. A method for adhering polyolefin articles.