JP2000280346A - Method for joining polyolefin tube - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve a joining characteristic of a polyolefin pipe even under a disadvantageous operating condition on a site affected by sticking of sand and a stain or the like. SOLUTION: In this joining method, a polyolefin pipe is joined by fusion weld via or without a polyolefin joint. In this case, a cloth having rayon as a main material is impregnated with organic solvent solution of a silicon compound, and the silicon compound is applied onto the fusion welded surface by using the impregnated material; or a tape formed of the silicon compound or a composition containing the silicon compound and polyolefin is allowed to exist on the fusion welded surface; or the silicon compound is transferred onto the fusion welded surface by using a pressure-sensitive adhesive tape to which an adhesive layer containing the silicon compound is provided.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for joining polyolefin tubes.

[0002]

2. Description of the Related Art As a method of joining polyolefin pipes, a method of joining via a polyolefin electrofusion joint (EF joint) or a heat fusion joint (HF joint), butt fusion A method for joining the end faces of a polyolefin pipe to each other is known.

Further, as a method for improving the joining characteristics of a polyolefin tube even under adverse working conditions such as adhesion of sand or dirt, a method of heat-sealing a polyolefin tube in a state where a silicon compound is present on the joining surface. Is known (WO98 / 4692
8). In the conventional embodiment according to this method, just before the fusion bonding process of the polyolefin pipe, the silicon compound is applied to the bonding portion such as the outer surface of the polyolefin pipe and the inner surface of the polyolefin joint by a known method as described below. .
That is, a silicon compound is dissolved in an organic solvent such as acetone or ethanol, and this solution is applied by attaching it to a paper tissue or a paper sheet, or by brushing or spraying.

Normally, the fusion surface needs to be cleaned immediately before the fusion bonding process of the polyolefin tube. Cleaning is performed by spraying acetone or ethanol onto paper tissue or paper sheet, or by impregnating paper tissue or paper sheet with acetone or ethanol and packing them in bottles that can be taken out one by one (a form similar to a so-called wet tissue). ). Therefore, by dissolving the silicon compound in an amount that provides a predetermined concentration in acetone or ethanol in advance, the fused surface can be cleaned and the silicon compound can be applied at the same time.

However, since lint (fine fiber pieces) is generated from paper tissue or paper sheet as a main material, lint remains on the fusion surface after the silicon compound coating step, and complete lint is generated. It may hinder wearing.

When the silicon compound is dissolved in acetone or ethanol in advance, the viscosity of the silicon compound solution is increased by increasing the concentration of the silicon compound solution because acetone and ethanol are rich in volatility, and sufficient cleaning performance is obtained. May not be possible. That is, it takes time to manage the concentration of the solution suitable for cleaning.

Further, if the paper tissue or paper sheet is once impregnated with the solution and left in an unused state, acetone and ethanol are volatilized and sufficient cleaning performance cannot be obtained. At this time, when a solution is further added, the concentration of the silicon compound becomes higher than a predetermined concentration. That is, it is necessary to separately prepare acetone or ethanol to maintain the concentration of the solution.

Further, when the organic solvent solution of the silicon compound is applied by brushing or spraying, it is difficult to uniformly distribute the silicon compound to the fused surface in a required appropriate amount without leaking over the entire surface. It is.

It is an object of the present invention to provide a method for significantly improving the joining characteristics of polyolefin tubes even under adverse operating conditions on site, such as the deposition of sand or dirt.

Another object of the present invention is to provide a method for uniformly dispersing a silicon compound in a required appropriate amount on the surface to be welded, without leaking over the entire surface.

It is another object of the present invention to provide a method in which foreign matter such as lint does not remain on a fusion surface after a step of applying a silicon compound.

Another object of the present invention is to provide a method that does not require concentration control of a silicon compound solution.

Another object of the present invention is to provide a method capable of reducing the chance of foreign matter adhering to a fusion surface.

[0014]

SUMMARY OF THE INVENTION The present invention provides a method for joining polyolefin pipes as described below. 1. With or without a polyolefin fitting,
At the time of joining the polyolefin tube by heat fusion, a silicon compound or a silicon compound and a reaction accelerator are adhered to a cloth mainly made of rayon, and the cloth is used to accelerate the reaction with the silicon compound or the silicon compound on the fusion surface. A method for joining polyolefin pipes, characterized by applying an agent. 2. With or without a polyolefin fitting,
At the time of joining the polyolefin tube by heat fusion, a cloth mainly made of rayon is impregnated with a silicon compound or an organic solvent solution of a silicon compound and a reaction accelerator, and a silicon compound or A method for joining polyolefin tubes, comprising applying a silicon compound and a reaction accelerator in advance. 3. With or without a polyolefin fitting,
When joining the polyolefin tube by heat fusion, cloth,
An organic solvent is impregnated into a paper tissue or paper sheet with a silicon compound or a silicon compound and a reaction accelerator adhered thereto, and the silicon compound or the silicon compound and the reaction accelerator are applied to the fused surface using the impregnated material. A method for joining polyolefin pipes. 4. With or without a polyolefin fitting,
A tape formed from a silicon compound or a silicon compound and a reaction accelerator, or a tape formed from a composition containing a polyolefin in addition to a silicon compound or a silicon compound and a reaction accelerator when the polyolefin tube is joined by heat fusion. Is present on the fused surface. 5. With or without a polyolefin fitting,
When joining the polyolefin pipe by heat fusion, using an adhesive tape provided with an adhesive layer containing a silicon compound or a silicon compound and a reaction accelerator, a silicon compound or a silicon compound and a reaction accelerator on the fusion surface. A method for joining polyolefin pipes, which is performed by transferring. 6. With or without a polyolefin fitting,
When joining the polyolefin pipes by heat fusion, using a heating device coated with a silicon compound or a silicon compound and a reaction accelerator, transferring the silicon compound or the silicon compound and the reaction accelerator to the fusion surface during heating. Characteristic method of joining polyolefin pipes.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION The joint made of polyolefin used in the present invention is not limited to an EF joint, but is an external heat source (heater).
HF joints using the same.

Known polyolefin tubes can also be used.

The silicon compound used in the present invention has a Si—Si bond, a Si—H bond, a Si—O bond or a Si—Si bond in the molecule.
X (X = at least one of a hydroxyl group, an alkoxy group, a halogen atom, an amino group, and an amide group) and Si-R (R = at least one of a hydrocarbon group such as an alkyl group, an alkenyl group, and an aryl group) Compound.

Examples of such a silicon compound are shown below.

1. Polysilane: Polysilane refers to a compound having at least one Si-Si bond in a main skeleton structure of a chemical structure, and a group generally represented by R ^{1 to} R ³ bonded to Si. Examples of such polysilanes include those represented by the following general formulas (1) to (3). General formula (1)

[0020]

Embedded image (Wherein, R ¹ and R ² are the same or different and each represent a hydrogen atom, a halogen atom, a hydroxyl group, an alkyl group having 1 to 20 carbon atoms, an alkenyl group, an aryl group, an alkoxy group, an amino group, an amide group, and a silyl group. M is usually about 20,000 to 10,000, more preferably 2
Linear polysilane and cyclic polysilane represented by the general formula (2):

[0021]

Embedded image (Wherein, R ³ is selected from the group consisting of a hydrogen atom, a halogen atom, a hydroxyl group, an alkyl group having 1 to 20 carbon atoms, an alkenyl group, an aryl group, an alkoxy group, an amino group, an amide group, and a silyl group; n is usually about 4 to 10000,
More preferably about 2 to 100, particularly preferably 2 to 1
A silicone network polymer represented by the general formula (3):

[0022]

Embedded image (Wherein R ^{1 to} R ³ are the same or two or more are different,
Selected from the group consisting of a hydrogen atom, a halogen atom, a hydroxyl group, an alkyl group having 1 to 20 carbon atoms, an alkenyl group, an aryl group, an alkoxy group, an amino group, an amide group, and a silyl group; Is usually about 5 to 10,000, more preferably about 5 to 100, and particularly preferably
(Approximately 5 to 10).

Such a polysilane compound is prepared by using a monomer having each structural unit as a raw material and a) dehalogenating polycondensation of a halosilane in the presence of an alkali metal ("Kipping method", J. Am. Chem. Soc., 110, 124 (198
8), Macromolecules, 23, 3423 (1991)) b) Dehalogenation polycondensation of halosilanes by electrode reduction (J. Ch.
em.Soc., Chem.Commun., 1161 (1990), J. Chem. Soc., Chem.
Commun., 897 (1992)), c) a method of dehydrocondensing hydrosilanes in the presence of a metal catalyst (JP-A-4-334551), a method of anionic polymerization of disilene cross-linked with biphenyl or the like (Macromolecules, 23,4494 (1990)) and ring-opening polymerization of cyclic disilanes.

As the polysilane, a linear polysilane and a cyclic polysilane represented by the general formula (1) are more preferable.

2. Polysiloxane: Polysiloxane is defined as having at least one Si in the main skeleton structure of the chemical structure.
A compound having a -O-Si bond and having a group generally represented by R (R = a hydrocarbon group such as an alkyl group, an alkenyl group, an aryl group) bonded to Si. Examples of such a polysiloxane include the following. General formula (4)

[0026]

Embedded image (Wherein, R ⁴ and R ⁵ are the same or different and each represent a hydrogen atom, a halogen atom, a hydroxyl group, an alkyl group having 1 to 20 carbon atoms, an alkenyl group, an aryl group, an alkoxy group, an amino group, an amide group, and a silyl group. Selected from the group consisting of
At least one of them is a hydrogen atom, a halogen atom, a hydroxyl group, an alkoxy group, an alkenyl group, an amino group or an amide group; m is about 2 to 10,000, more preferably about 2 to 100, and particularly preferably Is about 2 to 10), a linear polysiloxane and a cyclic polysiloxane represented by the general formula (5):

[0027]

Embedded image (Wherein R ⁴ is selected from the group consisting of a hydrogen atom, a halogen atom, a hydroxyl group, an alkyl group having 1 to 20 carbon atoms, an alkenyl group, an aryl group, an alkoxy group, an amino group, an amide group and a silyl group, At least one is a hydrogen atom,
Halogen atom, hydroxyl group, alkoxy group, alkenyl group,
An amino group or an amide group; X is about 4 to 10,000, more preferably about 4 to 100, and particularly preferably about 4 to 10), a network polymer represented by the general formula (6):

[0028]

Embedded image (Wherein, R ^{4 to} R ⁶ represent a hydrogen atom, a halogen atom, a hydroxyl group,
An alkyl group having 1 to 20 carbon atoms, an alkenyl group, an aryl group, an alkoxy group, an amino group, an amide group and a silyl group, at least one of which is a hydrogen atom, a halogen atom, a hydroxyl group, an alkoxy group, An alkenyl group, an amino group or an amide group; x, y and z
Is usually about 5 to 10,000, more preferably 5
About 100, and particularly preferably about 5 to 10), having a Si-O-Si bond as a skeleton.

3. General formula (7) R ⁴ R ⁵ R ⁶ R ⁷ Si (7) (wherein, R ^{4 to} R ⁷ are a hydrogen atom, a halogen atom, a hydroxyl group,
An alkyl group having 1 to 20 carbon atoms, an alkenyl group, an aryl group, an alkoxy group, an amino group and an amide group are selected from the group consisting of a hydrogen atom, an alkyl group having 1 to 20 carbon atoms, an alkenyl group and an aryl group. And at least one of a hydrogen atom, a halogen atom, a hydroxyl group, an alkoxy group, an amino group and an amide group).

Examples of the silicon compound represented by the general formula (7) include vinyltrichlorosilane, vinyltris (β-methoxyethoxy) silane, vinyltriethoxysilane, vinyltrimethoxylan, γ- (methacryloyloxypropyl) trimethoxysilane, β -(3,4-epoxycyclohexyl) ethyltrimethoxysilane, γ-glycidyloxypropyltrimethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, N-β (aminoethyl) γ-aminopropyltrimethoxysilane, N -β (aminoethyl)
γ-aminopropylmethyldiethoxysilane, γ-aminopropyltriethoxysilane, N-phenyl-γ-aminopropyltrimethoxysilane, γ-mercaptopropyltrimethoxysilane, γ-chloropropyltrimethoxysilane, vinyltrichlorosilane, vinyl Trimethoxysilane, vinyltriethoxysilane, tris- (2-methoxyethoxy) vinylsilane, γ-glycidoxypropyltrimethoxysilane, γ- (methacryloxypropyl) trimethoxysilane, γ (2-aminoethyl) aminopropyltrimethoxysilane Preferred are methoxysilane, γ-chloropropyltrimethoxysilane, γ-aminopropyltrimethoxysilane and the like.

The silicon compounds represented by the general formulas (1) to (7) may be used alone or in combination of two or more.

Among these silicon compounds, the polysilane represented by the general formula (1) is most preferred. Also,
When polysiloxane is used, a linear one is preferable, and a peroxide is preferably used in combination as a reaction accelerator shown below.

In the present invention, a reaction accelerator can be used in combination to promote the fusion reaction. As a reaction accelerator, benzoyl peroxide, dichlorobenzoyl peroxide, dicumyl peroxide, di-tert-butyl peroxide, 2,5-dimethyl-2,5-di
(Peroxybenzoate) hexyne-3,1,4-bis (tert-
(Butylperoxyisopropyl) benzene, lauroyl peroxide, tert-butylperacetate, 2,5-dimethyl-2,5-di (tert-butylperoxy) hexyne-3,2,
5-dimethyl-2,5-di (tert-butylperoxy) hexane,
tert-butyl perbenzoate, tert-butyl perphenyl acetate, tert-butyl perisobutyrate, tert-butyl
Peroxides and peresters such as butyl per-tert-octoate, tert-butyl perpivalate, cumyl perpivalate, and tert-butyl perdiethyl acetate; azo compounds such as azobis-isobutyronitrile and dimethylazoisobutyrate And at least one compound such as acetic acid, p-toluenesulfonic acid, and hydrochloric acid; and bases such as pyridine and triethylamine. Among the compounds that generate radicals, dicumyl peroxide, di-tert-butyl peroxide, 2,5-dimethyl-2,
5-di (peroxybenzoate) hexyne-3,2,5-dimethyl-2,5-di (tert-butylperoxy) hexane, 1,4-bis
Dialkyl peroxides such as (tert-butylperoxyisopropyl) benzene are more preferred.

In carrying out the method of the present invention, a predetermined silicon compound or a silicon compound and a reaction accelerator are applied to the outer surface of the polyolefin tube and / or the fusion surface of the inner surface of the polyolefin joint, and then the tube is inserted into the joint. rear,
Heating may be performed according to a conventional method, or a predetermined silicon compound or a silicon compound and a reaction accelerator may be applied to the polyolefin pipe end faces, and the polyolefin pipe end faces may be joined to each other by butt fusion.

The present invention is characterized by a method of applying a silicon compound or a silicon compound and a reaction accelerator to the fused surface. As the method, the following may be mentioned.

(1) A method in which a silicon compound or a silicon compound and a reaction accelerator are adhered to a cloth mainly made of rayon, and the silicon compound or the silicon compound and the reaction accelerator are applied to the fused surface using the cloth. In order to apply the compound or the silicon compound and the reaction accelerator to the fused surface of a polyolefin tube or the like, a cloth mainly made of rayon (preferably, a nonwoven fabric is preferable to a woven fabric from the viewpoint of cost) with a silicon compound or a silicon compound is used. A reaction accelerator can be applied and applied to the fused surface. Rayon is an artificial fiber and has a longer fiber length than pulp.
The amount of lint (fine fiber pieces) generated is smaller than that of pulp-based paper (such as nonwoven fabric). Therefore, there is little possibility that foreign matter is left on the fusion surface, and there is little risk of preventing complete fusion. As a secondary material other than rayon in cloth,
Pulp and the like. The ratio of rayon in the cloth is usually
It is about 50 to 100% by weight, preferably about 100% by weight.

The amount of the silicon compound applied to the fused surface is as follows:
Although not particularly limited, but is usually from 0.001 to 100 g / m ^2, and more preferably about 0.01 to 50 g / m ^2. The amount of the reaction accelerator used is not particularly limited, either.
Usually, it is about 0.1 to 100% by weight of the silicon compound, more preferably about 0.5 to 40%.

(2) A cloth mainly composed of rayon is impregnated with a silicon compound or a solution of a silicon compound and a reaction accelerator in an organic solvent, and the impregnated material is used to bond the silicon compound or the silicon compound and the reaction accelerator to the fused surface. In general, before fusing a polyolefin tube, the fused surface is cleaned with an organic solvent such as acetone or ethanol. By applying a silicon compound or the like with a cloth impregnated with a silicon compound or an organic solvent solution of a silicon compound and a reaction accelerator, the silicon compound and the like can be applied to the fused surface and the fused surface can be cleaned.

The cloth mainly made of rayon is the same as described above.

As the organic solvent, acetone, toluene, xylene, benzene, ethanol, methanol, isopropanol, n-propanol, butanol, tetrahydrofuran, dimethoxyethane, dimethylacetamide, and ethylene glycol conventionally used for wiping the tube surface are used. , Triethylene glycol, tetraethylene glycol and the like can be used.

The ratio of the silicon compound to the solvent is not particularly limited, but is usually about 0.1 to 100 parts by weight, more preferably about 1 to 40 parts by weight, based on 100 parts by weight of the solvent. When using a reaction accelerator, 10 parts by weight of the silicon compound, the solubility of the solvent or less,
It is preferably at most 10 parts by weight, more preferably at most 4 parts by weight.

(3) A cloth, paper tissue or paper sheet having a silicon compound or a silicon compound and a reaction accelerator adhered to an organic solvent is impregnated with the organic solvent. And a method of applying a reaction accelerator. A silicon compound or the like is dissolved in a solvent such as acetone or ethanol, and the solution is impregnated into a cloth (or a paper tissue or a paper sheet) such as a nonwoven fabric mainly composed of rayon. In the case where the silicon compound is applied by using it to clean the fused surface, the solvent (acetone or ethanol) is volatilized during storage of the impregnated cloth, and there is a possibility that sufficient cleaning cannot be performed. On the other hand, in the present method, a predetermined amount of acetone or ethanol is impregnated immediately before the coating operation, so that the coating operation also serves as a cleaning operation before the solvent volatilizes in a large amount. That is, it is not necessary to control the concentration of the solution. In addition, even when once impregnated with the solvent and left unused, the initial state can be reproduced by additionally impregnating the solvent.

The organic solvent is the same as described above.

(4) A tape formed from a silicon compound or a silicon compound and a reaction accelerator, or a tape formed from a silicon compound or a composition containing a silicon compound and a reaction accelerator further containing a polyolefin, Method for Presence According to this method, the silicon compound or the silicon compound and the reaction accelerator can be uniformly distributed on the fused surface in a required appropriate amount in the entire surface without any leakage.

The polyolefin in the composition for forming the tape includes polyethylene, polypropylene, polybutene, polymethylpentene and the like. This polyolefin is preferably of the same type as the polyolefin tube.

The content of the silicon compound in the composition forming the tape is usually about 16 to 99% by weight, preferably about 50 to 95% by weight. When a reaction accelerator is contained, the amount used is usually 0.1 to 1 based on the weight of the silicon compound.
It is about 00%, more preferably about 0.5 to 40%.

In order for the tape to be present on the fusion surface, for example, the tape may be wound around the outer surface of a polyolefin tube. After interposing the tape on the fusion surface in this way,
By heating, the joint is heated and fused via the tape.

(5) A method of transferring the silicon compound or the silicon compound and the reaction accelerator to the fused surface using an adhesive tape provided with an adhesive layer containing the silicon compound or the silicon compound and the reaction accelerator. Surface), a pressure-sensitive adhesive tape provided with a silicon compound or a pressure-sensitive adhesive layer containing a silicon compound and a reaction accelerator is attached to the bonding surface before fusion, and the tape is removed after transferring the silicon compound and the like to the fusion surface. Then, heat fusion may be performed.

According to this method, the silicon compound or the silicon compound and the reaction accelerator can be uniformly distributed in the required appropriate amount on the surface to be fused, without leaking over the entire surface.
Also, by attaching tape in the process of manufacturing polyolefin pipes and polyolefin joints and removing it just before fusion,
It is possible to omit the cleaning work of the fusion surface required before the fusion, and it is possible to reduce the chance of foreign matter adhering to the fusion surface.

As the tape base, those used for ordinary adhesive tapes can be used. For example, paper, plastic film and the like can be mentioned.

As the pressure-sensitive adhesive, a commonly used pressure-sensitive adhesive can be used. For example, natural rubber, SB
Adhesives such as R (styrene butadiene rubber), butyl rubber, acrylic, and vinyl acetate can be used.

The content of the silicon compound in the pressure-sensitive adhesive layer is usually about 16 to 99 parts by weight, preferably about 50 to 95 parts by weight, based on 100 parts by weight of the pressure-sensitive adhesive forming the pressure-sensitive adhesive layer. When a reaction accelerator is contained, the amount used is usually about 0.1 to 100%, more preferably about 0.5 to 40% of the weight of the silicon compound.

(6) A method of transferring the silicon compound or the silicon compound and the reaction accelerator to the fusion surface during heating using a heating device coated with the silicon compound or the silicon compound and the reaction accelerator HF fusion or butt fusion When joining a polyolefin pipe by heating, a silicon compound or a silicon compound and a reaction accelerator are applied to a heater which is a heating device for heating and melting the polyolefin pipe and the like. After transferring the compound or the like, fusion may be performed.

According to this method, since the fusing operation can be performed immediately after the cleaning operation required before the fusing, the chance of foreign matter adhering to the fusing surface can be reduced.

[0055]

According to the present invention, the joining characteristics of the polyolefin pipe are remarkably improved even under adverse working conditions such as adhesion of sand and dirt.

According to the present invention, when the polyolefin pipes are joined by heat-sealing, the chance of foreign matters adhering to the fused surface is reduced, and the silicon compound is applied to the fused surface in a necessary and appropriate amount. It can be uniformly distributed without leaking over the entire surface.

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Hiroyuki Nishimura 4-1-2, Hirano-cho, Chuo-ku, Osaka-shi, Osaka Inside Osaka Gas Co., Ltd. (72) Inventor Yuichiro Yamaguchi 4-chome, Hirano-cho, Chuo-ku, Osaka, Osaka 1-2-2 Inside Osaka Gas Co., Ltd. (72) Inventor Hiroaki Murase 4-1-2 Hirano-cho, Chuo-ku, Osaka-shi, Osaka F-term inside Osaka Gas Co., Ltd. 3H019 GA02 GA06 4F071 AA14 AA14B AA65A AA67A AC16A AG31 CA02 CB01 CB02 CC06 CD02 4F211 AA01 AA03 AB04 AB22 AD12 AD16 AD34 AG08 TA01 TA03 TC11 TD07 TH02 TH22 TH23 TJ30 TN53 TN58 TN60 TN88

Claims (6)

[Claims] When a polyolefin pipe is joined by heating and fusing with or without a polyolefin joint, a silicon compound or a silicon compound and a reaction accelerator are attached to a cloth mainly made of rayon. A method for joining polyolefin pipes, comprising applying a silicon compound or a silicon compound and a reaction accelerator to a fusion surface using a cloth. 2. A method for joining a polyolefin pipe by heating and fusing it with or without a polyolefin joint, wherein a rayon-based cloth is coated with a silicon compound or an organic solvent solution of a silicon compound and a reaction accelerator. A method for joining polyolefin pipes, comprising impregnating a silicon compound or a silicon compound and a reaction accelerator on a fused surface using the impregnated material. 3. A method in which a silicon compound or a silicon compound and a reaction accelerator are attached to a cloth, a paper tissue or a paper sheet when a polyolefin pipe is joined by heating and fusing with or without a polyolefin joint. A silicon compound or a silicon compound and a reaction accelerator are applied to the surface to be fused using the impregnated material. 4. A tape formed from a silicon compound or a silicon compound and a reaction accelerator, or a tape formed from a silicon compound or a silicon compound when a polyolefin pipe is joined by heating and fusing with or without a polyolefin joint. A method for joining polyolefin pipes, wherein a tape formed from a composition further containing a polyolefin in a reaction accelerator is present on a fusion surface. 5. A pressure-sensitive adhesive tape provided with a pressure-sensitive adhesive layer containing a silicon compound or a silicon compound and a reaction accelerator when bonding and joining a polyolefin tube by heating with or without a polyolefin joint. And transferring a silicon compound or a silicon compound and a reaction accelerator to the fusion-bonded surface. 6. A heating device coated with a silicon compound or a silicon compound and a reaction accelerator when heating and bonding a polyolefin tube with or without a polyolefin joint, and the tube is fused during heating. A method for joining a polyolefin pipe, comprising transferring a silicon compound or a silicon compound and a reaction accelerator to a surface.