JPS6351126A - Method for connecting polyolefin tube to tube made of different material - Google Patents

Abstract

PURPOSE:To easily land strongly connect a polyolefin tube to various kinds of tubes, each of which is made of material different from polyolefin by a method wherein the connection between them is done through a polyolefin joint, the connection of which to the polyolefin tube is done with water crosslinkable polyolefin adhesive and the connection of which to the tube made different material is done with adhesive, which is selected from epoxy-based, urethane-based, silicone-based and cyanoacrylate-based adhesives. CONSTITUTION:The bonding connection of a polyolefin tube to a polyolefin joint is done with water crosslinkable polyolefin adhesive. The bonding connection of the polyolefin joint to a tube made of different material is done at normal temperature with at least one kind of adhesive, which is selected from the group consisting of epoxy-based, urethane-based, silicone-based and cyanoacrylate-based adhesives. Thus, the polyolefin tube and the tube made of different material are connected to each other through the polyolefin joint. In addition, the surface of the tube to be connected and made of different material, is polished in advance. On the other hand, the surface of the polyolefin tube is also polished and treated by heating heavily in advance. Said heat treatment is done at a temperature as high as possible and for a period of time as short as possible for preventing the deformation due to heat from occurring. The preferable temperature and period of time for said treatment are 500 deg.C or higher and about 0.5-10 seconds.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for connecting polyolefin pipes such as cross-linked polyethylene pipes to various types of pipes other than polyolefin pipes, such as metal pipes and polyvinyl chloride pipes.

Conventional techniques and solutions 1A polyolefin has excellent chemical resistance and corrosion resistance, and polyolefin pipes are used as factory piping to transport acids and alkaline liquids, such as hot water pipes in buildings. Recently, the number of cases where they are used as gas pipes, water pipes, etc. buried underground has increased. Pipes for each of the above uses have conventionally been metal pipes such as iron pipes and steel pipes, polyvinyl chloride pipes, nylon pipes, and FR pipes.
Since pipes other than polyolefin pipes such as P pipes (hereinafter, cough pipes are referred to as dissimilar pipes) have been used, it has become necessary to connect the newly installed polyolefin pipes and the existing dissimilar pipes.

There are two ways to connect pipes: mechanical connection using metal fittings and adhesive connection using adhesive. It has the disadvantage of high cost. On the other hand, the method of using an adhesive has the problem that, as is well known, polyolefin is a material that is extremely difficult to adhere to, and therefore cannot be adhered with ordinary adhesives or adhesive methods.

The connection method using metal joints has the disadvantage of high cost,
In addition, in view of the fact that a sufficient connection cannot be achieved with the conventional adhesive connection method, the present invention aims to provide a new adhesive connection method between a polyolefin pipe and a different type of pipe. This is an adhesive connection method using an adhesive.

That is, in the present invention, when connecting a polyolefin pipe and a dissimilar pipe using a polyolefin joint, the polyolefin pipe and the polyolefin joint are connected using a water-crosslinkable polyolefin adhesive, and the dissimilar pipe and the polyolefin joint are connected using an epoxy adhesive. At least one selected from the group consisting of urethane-based, urethane-based, silicone-based, and cyanoacrylate-based
This is a method of connecting a polyolefin pipe and a different type of pipe, which is characterized by using a type of adhesive for connection.

A dish polyolefin pipe and a polyolefin joint can be adhesively connected using a water-crosslinkable polyolefin adhesive, and a polyolefin joint and a dissimilar pipe can be connected using an epoxy adhesive,
Adhesive connection can be performed at room temperature using at least one type of adhesive selected from the group consisting of urethane-based, silicone-based, and cyanoacrylate-based adhesives. Therefore, the polyolefin pipe and the different type of pipe are connected via the polyolefin joint. Note that the surfaces of the dissimilar pipes to be connected are polished, and the surfaces of the polyolefin joints to be bonded are polished and then ignited. By using one type of adhesive, both can be bonded more firmly.

In the present invention, the polyolefin that is the constituent material of the polyolefin pipes and polyolefin joints to be connected may be homopolymers or copolymers of α-olefins such as ethylene, propylene, and butene-1, such as high-density polyethylene, density polyethylene, low density polyethylene,
Polyethylenes such as extremely low density polyethylene and linear low density polyethylene, polypropylene, polybutene-1,
Various copolymers of ethylene and various copolymerizing agents other than α-olefins, such as poly-4-methylpentene-1, ethylene-propylene copolymer, ethylene-butene-1 copolymer, etc., such as ethylene-vinyl acetate copolymer Polymers, ethylene-methyl acrylate copolymers, ethylene-ethyl acrylate copolymers, or the above polyolefins are cross-linked to a low or high degree by peroxide cross-linking, irradiation cross-linking, water cross-linking or other methods. Examples include polyolefins.

A polyolefin pipe and a polyolefin joint are connected using an adhesive mainly composed of a water-crosslinkable polyolefin having a hydrolyzable silane group represented by the following general formula (1) in the main chain or side chain. Ru.

(Hereinafter, blank space) -3i-Y ・ ・ ・ ・ ・ (1) Rz Here, Y is a hydrolyzable organic group having 20 or less carbon atoms, and R1 and R2 are each a group Y or a hydrolyzable organic group having 20 or less carbon atoms. It is a saturated batter base.

Examples of the group Y include alkoxy groups such as methoxy, ethoxy and butoxy groups, acyloxy groups such as formyloxy, acetoxy and probionoxy groups, -0N=C(
CH3)z, -0N=C(CHz)CtHs.

-0N=C(C,R5)! oximo groups such as -
NHGHz, -NtlCJs, -Nll(C6H5)
and substituted amino groups such as. Examples of the group R5 and the group R2 include a methyl group, an ethyl group, a propyl group, a tetradecyl group, an octadecyl group, a phenyl group, a benzyl group, a tolyl group, or those exemplified as examples of the group Y above.

The content of the hydrolyzable silane group is preferably about 0.001 to 20% by weight. If it is less than 0.001% by weight,
The adhesive itself has poor water cross-linking properties, resulting in weak adhesive strength. On the other hand, 2
When the amount is more than 0% by weight, the water crosslinking property becomes excessive, resulting in poor handling properties. Therefore, the content of the hydrolyzable silane group is particularly preferably about 0.05 to 5% by weight.

Further, as the water-crosslinkable polyolefin, ASTM
Melt index measured by D-1238 (
Ml) is 0.1 to 20, especially 0. 5 to 5 is preferred. If Ml is less than 0.1, the melt viscosity is too high and the applicability to the adhesive surface is poor (on the other hand, if Ml is less than 2
If it is larger than 0, the mechanical strength of the adhesive itself is weak and the adhesive strength tends to be low.

The water-crosslinkable polyolefin that is the main component of the adhesive used in the present invention is, for example, a mixture of a polyolefin described later, a t1 release radical generator, and an unsaturated organic silane compound represented by the following general formula (2). It is obtained by heating to a high temperature higher than the decomposition temperature of the free radical generator.

R3Ra, IS + Y(1-, 11HH+ (2)
Here, R1 is an unsaturated organic group having 20 or less carbon atoms directly bonded to the Si atom, Y is the same concept as in the above general formula (1), R4 is a saturated organic group or group Y having 20 or less carbon atoms, , , are 0.1 or 2.

As the above-mentioned polyolefin, a homopolymer or copolymer of the α-olefin described above with respect to the polyolefin pipe to be bonded, or a copolymer of an α-olefin with another copolymer agent, etc. can be used. Particularly preferred are those that, in a water-crosslinked state, have a tensile strength equal to or higher than that of the polyolefin constituting the pipe to be bonded (including its crosslinked products).

Preferred polyolefins include: (11 Linear low density polyethylenes.

In particular, it is a copolymer of olefin having 4 to 16 carbon atoms and ethylene, with a density of 0.88 to 0.94 and an Ml of 0.1.
~20 things. Such polyethylene may be made of, for example, at least one olefin having 4 to 16 carbon atoms and ethylene (approximately 1 to 20 parts by weight, preferably 5 to 10 parts by weight, of the olefin per 100 parts by weight of ethylene). Under normal pressure to 20℃ in the presence of catalyst etc.
It is obtained by polymerization reaction under atmospheric pressure, preferably normal pressure to low pressure of about 10 atmospheres. Commercially available products include Mitsubishi Polyethylene LL and H.
20E, F30F, F30H (all manufactured by Mitsubishi Yuka Corporation)
, Urtozesox 202OL, 3010F, 3021F
(all manufactured by Mitsubishi Yuka), DFDA-7540 (manufactured by Union Carbide), NUCG-5651, G5
-650. GR3N-7047, GR3N-7042
(both manufactured by Nippon Unicar Co., Ltd.'!A), Idemitsu polyethylene, 0134H, 0234H (all manufactured by Idemitsu Petrochemical Co., Ltd.), and the like.

(2) High-density polyethylenes.

In particular, those having a density of 0.93 or more, preferably 0.94 or more, and an Ml of 0.1 to 5.

+31 Copolymer of α-olefin with carbon number M of 3 to 10 and ethylene.

In particular, ethylene made with Ziegler catalyst and carbon number 3-1
A copolymer with 0 α-olefin, the α-olefin content is 0.5 to 50% by weight, especially 5 to 30% by weight,
Density 0.85-0.90, later. Commercially available products include Tafmer A-4090, A-4085, P-0180, P
-0480 (all manufactured by Mitsui Petrochemicals), etc.

Examples of free radical generators include dicumyl peroxide, 2,5-dimethyl-2,5-di(1-butylperoxy)hexyne-3,1,3-bis-(1-butylperoxyisopropyl)benzene, etc. Examples include organic peroxide crosslinking agents.

Examples of the unsaturated silane compound represented by the -S formula (2) include vinyltrimethoxysilane and vinyltriethoxysilane.

Specific examples of free radical generators and unsaturated organic silane compounds other than those mentioned above include, for example, Japanese Patent Publication No. 50-126789
Also included are those disclosed in Japanese Patent Publication No. 50-35940.

In order to obtain a water-crosslinkable polyolefin using the above-described polyolefin, a free radical generator, and an unsaturated organic silane compound, the polyolefin and the polyolefin 10
0.01 to 10 parts by weight, preferably 0.01 to 10 parts by weight.
0.05 to 1 part by weight of a free radical generator and 0.05 to 20 parts by weight
The mixture with parts by weight, preferably from 1 to 5 parts by weight, of an unsaturated organosilane compound is heated at a temperature and for a time sufficient to decompose the free radical generator. This heating causes the unsaturated organic silane compound to graft onto the polyolefin and modify it into a water-crosslinkable polyolefin. The heating required for this denaturation is
It varies depending on the decomposition property of the free radical generator used; for example, in the case of dicumyl peroxide, the
20 minutes, 30 seconds to 2 minutes at 200°C.

The water-crosslinkable polyolefin adhesive used in the present invention may optionally contain an agent that promotes the water-crosslinking reaction of the water-crosslinkable polyolefin, such as a silanol condensation catalyst, such as dibutyl-tin-dilaurate.

The water-crosslinkable polyolefin adhesive used in the present invention may be used alone, or may be used in a suitable aqueous solvent such as benzene, toluene, xylene, durene, mezinalene,
Hydrocarbons such as decalin and liquid olefin oligomers,
Other compounds such as tetrahydrofuran, methyl isobutyl ketone, cyclohexanone, trichlorethylene, etc.
? It may be used in the form of a solution or dispersion of the f1 form.

In the present invention, if the surfaces of the polyolefin pipe to be connected and the polyolefin joint are clean and free of dust, oil, etc., no special surface treatment is required, but after the cleaning treatment, the surfaces of the polyolefin pipe and the polyolefin joint are further coated with sandpaper, etc. It is desirable to roughen the surface.

In addition, in order to improve the compatibility between the water-crosslinkable polyolefin adhesive and the object to be adhered, the object to be adhered is heated to a high temperature of at least 100°C or higher, particularly 150 to 250°C, prior to applying the adhesive. At least the melting point of the water-crosslinkable polyolefin in the adhesive is maintained, especially 60 to 2
It is desirable to apply a water-crosslinkable polyolefin adhesive or an organic solvent solution thereof heated to 00°C. Although it is not necessarily necessary to apply the water-crosslinkable polyolefin adhesive to both the polyolefin pipe and the polyolefin joint, it is desirable to apply the above-mentioned heating to both.

Next, a method of connecting the polyolefin joint and different types of pipes will be explained.

As for the different types of pipes, the above-mentioned pipes and various other pipes can be connected, and among them, polyvinyl chloride pipes, metal pipes, especially iron pipes, steel pipes, aluminum pipes, steel pipes, lead pipes, etc. can be connected well.

In the present invention, it is desirable to first perform the following pretreatment on each surface of the dissimilar pipe and the polyolefin joint prior to bonding.

For dissimilar pipes, the surface is polished to remove rust (in the case of metal pipes) and foreign matter from the surface layer and to create irregularities to increase the effective bonding area. For example, it is preferable to uniformly polish the surface of the tube using an abrasive material or polishing means having a particle size of No. 30 to No. 400 specified in JIS-R6001. As the abrasive material, abrasive cloth (JIS-R6521), abrasive paper (
JIS-R6252), abrasive belt (JIS-R625
2), abrasive Jinuku (JIS-R6255), etc. can be used. If the abrasive grain size is finer than No. 400, workability will be poor.
It may be difficult to polish uniformly, and a sufficient effect may not be expected. On the other hand, if the polishing is rougher than 30@3, the dissimilar pipe may be damaged, so care must be taken.

The inner surface of the polyolefin joint is first polished in the same manner as described for the dissimilar pipe. In this case as well, it is preferable to use an abrasive material or polishing means having a particle size of No. 30 to No. 400 according to JIS-R6001.

Next, the polished inner surface of the polyolefin joint is subjected to ignition treatment. A wide range of known methods such as flame treatment and hot air treatment can be applied to this ignition treatment. Gas burners can be used for flame treatment, and hot jets can be used for hot air treatment. When carrying out the ignition treatment, it is desirable to uniformly apply flame or hot air of at least 250°C or higher to the inner surface of the polyolefin for at least 0.1 seconds without burning the surface of the polyolefin to be bonded. Although it depends on the JI, shape, etc. of the polyolefin joint, in order to prevent the polyolefin joint from deforming due to heat, it is preferable to perform it at as high a temperature as possible and in a short time from the viewpoint of workability. A treatment time of about 0.5 to 10 seconds is more preferable.

In the present invention, the above-mentioned pretreated dissimilar pipe and polyolefin joint are then bonded together using the following adhesive. As adhesives, epoxy adhesives, urethane adhesives, silicone adhesives, and cyanoacrylate adhesives may be used alone, or two or more types may be used in combination.

As the epoxy adhesive, a wide variety of conventionally known adhesives can be used, such as those containing a bisphenol A type epoxy resin, an amine curing agent, a polyamide resin or a polysulfide resin curing agent, etc. The bisphenol A type epoxy resin preferably has an epoxy equivalent of 140 to 300 and is liquid at room temperature.

In addition, as amine-based curing agents, aliphatic amines (primary,
(secondary and tertiary), aromatic amines, polyamide amines, and modified products thereof, among which those that are liquid at room temperature are preferred. Conventional fillers, colorants, reactive diluents, etc. can also be added to such epoxy adhesives. The epoxy adhesive is usually used by mixing an epoxy resin and a curing agent immediately before bonding, and after bonding at room temperature, it may be heated at a relatively low temperature of 50 to 60° C. if necessary.

As the urethane adhesive, a wide variety of conventionally known adhesives can be used, such as those blended with polyisocyanate and polyol. The polyisocyanate is preferably one that is liquid at room temperature, and the polyol is preferably a polyol or polyurethane polyol that is liquid at room temperature. Conventional fillers, colorants, curing catalysts, etc. can also be added to such urethane adhesives. Like the epoxy adhesive, the urethane adhesive is used by mixing it with polyisocyanate toboriol immediately before bonding.

As the silicone adhesive, a wide range of conventionally known ones can be used, such as room temperature curing silicone adhesives,
It can be roughly divided into two-component type and one-component type.

The two-component type is a mixture of polysiloxane having an OH terminal (terminally reactive polysiloxane) and a crosslinking agent such as tetraalcodisilane or tetraalkyl titanate. −
The liquid type is mainly composed of polysiloxane containing acetoxy groups (acetic acid generating type), polysiloxane containing alkoxy groups (alcohol generating type), etc., and has a curing catalyst,
Fillers and the like may be added as appropriate.

As the cyanoacrylate adhesive, a wide variety of conventionally known adhesives can be used, including those containing α-cyanoacrylic acid ester as a main component. Examples of the α-cyanoacrylic acid ester include α-cyanoacrylic acid methyl α-ethyl cyanacrylate.

When bonding dissimilar pipes and polyolefin joints to each other using the above adhesive, it is sufficient to apply the above adhesive to one or both of the two to be bonded at room temperature to bring them into contact. Pressure or heating may be applied as appropriate. The optimal amount of adhesive to be applied varies depending on the type of adhesive used, the material to be bonded, the form, etc., and cannot be generalized, but in general, a thickness of about 0.01 to 1 mm is applied to the surface to be bonded. There is no particular restriction on the method of applying the adhesive, and a wide range of commonly used means can be used.

According to the present invention, various types of different types of pipes and polyolefin pipes can be easily and firmly connected. In general, pipes of different types are often used for existing pipes, and in the past, due to the difficulty of connection, pipes of the same type were unavoidably used even if there was some dissatisfaction with the service life of pipes connected to different pipes. However, the present invention makes it possible to employ polyolefin pipes with excellent chemical resistance and corrosion resistance.

EXAMPLES The present invention will now be described in more detail with reference to Examples and Comparative Examples. In the following, parts and % mean parts by weight and % by weight, respectively, unless otherwise specified.

Example 1 0.15 parts of dicumyl peroxide and 2.0 parts of vinyltrimethoxysilane were added to 100 parts of high-density polyethylene with a density of 0.94.5 g/Cm' and a melt intex of 0.2 g/10 minutes. The mixture was mixed, graft-modified for about 2 minutes using an extruder whose temperature was adjusted to 200°C, and then molded into a pipe to obtain a crosslinked polyethylene pipe with a nominal diameter of 32 mA and a degree of crosslinking of 70%. In addition, as a different kind of pipe, a polyvinyl chloride pipe for water supply specified in JIS K6742 was prepared.

The above cross-linked polyethylene pipe and density 0.945g/Cm3
, nominal diameter 32 made of crosslinked polyethylene with a degree of crosslinking of 70%
When connecting a mA socket-type joint, first polish the connecting surfaces of both with 150-grit sandpaper, then heat the inner surface of the joint and the outer surface of the pipe at 230°C for 10 seconds, and then heat to approximately 130°C. The following adhesive was applied, heated again to the same temperature as above, and the pipe was inserted into the joint and connected.

The adhesive used was 0.1 part of dicumyl peroxide and 2.0 parts of vinyltrimethoxysilane per 100 parts of linear polyethylene with a density of 0.929 g/cm' and a melt index of 2.3 g/10 minutes. Mix and heat to 200℃
A water-crosslinkable adhesive (adhesive-1) obtained by grafting modification for about 2 minutes in an extruder whose temperature was adjusted to 100% and then dissolving 10% in xylene was used.

To connect the PVC pipe and the fitting, first sand the connecting surfaces of both with 150-grit sandpaper, then flame-treat the connecting surfaces of the fitting with a torch gas burner for about 5 seconds, and then apply epoxy to both adhesive surfaces. After applying the adhesive, the pipe was inserted into the fitting and connected.

Example 2 Pipe connections were made in exactly the same manner as in Example 1, except that urethane adhesive was used instead of epoxy adhesive.

Example 3 Pipe connections were made in exactly the same manner as in Example 1, except that cyanoacrylate adhesive was used instead of epoxy adhesive.

Example 4 Pipe connections were made in exactly the same manner as in Example 1, except that a steel pipe was used as the dissimilar pipe instead of the polyvinyl chloride pipe.

Example 5 Density 0.945 g/cm", melt index 0.
0.1 part of dicumyl peroxide and 2.0 parts of vinyltrimethoxysilane were mixed with 100 parts of high-density polyethylene of 2 g/10 minutes, and after graft modification for about 2 minutes in an extruder whose temperature was adjusted to 200°C. Adhesive-1 is a water-crosslinkable adhesive (Adhesive-2) obtained by dissolving 10% in xylene.
Pipe connections were made in exactly the same manner as in Example 1, except that a silicon adhesive was used instead of the epoxy adhesive.

Example 6 Pipe connections were made in exactly the same manner as in Example 1, except that an FRP pipe was used as a different type of pipe instead of a polyvinyl chloride pipe.

Example 7 Pipe connections were made in exactly the same manner as in Example 1, except that a nylon pipe was used as the dissimilar pipe instead of the polyvinyl chloride pipe, and a urethane adhesive was used instead of the epoxy adhesive.

Example 8 Pipe connections were made in exactly the same manner as in Example 1, except that polypropylene pipes were used instead of cross-linked polyethylene pipes, steel pipes were used instead of polyvinyl chloride pipes, and cyanoacrylate adhesives were used instead of epoxy adhesives. I did it.

Comparative Example 1 Pipe connections were made in exactly the same manner as in Example 1, except that an adhesive for polyvinyl chloride pipes was used instead of the epoxy adhesive.

Comparative Example 2 An ethylene-vinyl acetate copolymer with a melt index of 20 g/10 minutes and a vinyl acetate content of 20% was added to xylene for 1 hour.
Adhesive (Adhesive-3) obtained by dissolving 5% of adhesive (Adhesive-1)
Pipe connections were made in exactly the same manner as in Example 1, except that steel pipes were used instead of polyvinyl chloride pipes.

Comparative Example 3 A pipe connection was made that differed from Example 4 only in that the inner surface of the joint was not flame treated.

The details of the adhesives other than adhesives-1 to -3 used above are as follows.

Epoxy adhesive: Product name Arteco 3 manufactured by Alpha Giken Co., Ltd.
500 Urethane adhesive: Product name Unibon 800 manufactured by Sanyo Chemical Co., Ltd.
0 Cyanoacrylate adhesive: Trade name Aron Alpha 232 manufactured by Toagosei Co., Ltd. Silicone adhesive: Trade name KE7RTV manufactured by Shin-Etsu Chemical Co., Ltd. Adhesive for polyvinyl chloride pipes: Trade name AV manufactured by Asahi Yokuzai Co., Ltd.
Adhesive 52 Breaking water pressure test: A breaking water pressure test specified in JIS K6774 was carried out on a sample having a length of about 1000 nm in the center and having a connecting part in the center taken from each connecting pipe obtained in Examples 1 to 8 and Comparative Examples 1 to 3. I did it. Note that Examples 1.2.3.7 and Comparative Example 1 were tested at a test temperature of 20°C, while the remaining Examples and Comparative Examples were tested at a test temperature of 80°C.

The results are shown in Table 1.

As is clear from the upper table of Table 1, in the comparative example there was an abnormality in which liquid leaked from the connection part, whereas in all of the examples, the pipe part was destroyed and there was no abnormality in the connection part.

Claims (1)

[Claims] 1. When connecting a polyolefin pipe and a different type of pipe using a polyolefin joint, the polyolefin pipe and the polyolefin joint are connected using a water-crosslinkable polyolefin adhesive, and the different type of pipe and the polyolefin joint are connected using a water-crosslinkable polyolefin adhesive. A method for connecting polyolefin pipes and dissimilar pipes, characterized in that the connection is made using at least one type of adhesive selected from the group consisting of epoxy, urethane, silicone, and cyanoacrylate adhesives. 2. The connection method according to claim 1, wherein the different type of pipe is at least one type selected from the group consisting of a metal pipe, a polyvinyl chloride pipe, an FRP pipe, and a nylon pipe. 3. When connecting dissimilar pipes and polyolefin joints, the surfaces of the dissimilar pipes to be connected are polished, while the surface of the polyolefin joint is polished and then subjected to intense heat treatment, and then adhesive is used to bond the two surfaces together. A connection method according to any one of claims 1 to 2. 4. The water-crosslinkable polyolefin adhesive has the following general formula ▲ Numerical formula, chemical formula, table, etc. ▼ (Here, Y is a hydrolyzable organic group having 20 or less carbon atoms, and R_1 and R_2 are each or a saturated organic group having 20 carbon atoms or less. The connection method described in any of the sections.