JPH0726239A - Adhesive for lining pipe with synthetic resin - Google Patents

Abstract

PURPOSE:To obtain an adhesive which enables a synthetic-resin-lined pipe excellent in resistance to thermal shock to be obtd. even when a metal pipe is lined with a chlorine-contg. resin. CONSTITUTION:This adhesive comprises 100 pts.wt. satd. polyester resin having a carboxyl equivalent of 300-4,000 and a wt.-average mol.wt. of 1,000-6,000, 5-50 pts.wt. epoxy compd., and 1-50 pts.wt. powdered polyolefinic resin having an average particle size of 1-100mum provided that the epoxy compd. contains tri- or tetraepoxy compd. in an amt. of 10mol% or higher based on the sum of the resin and the epoxy compd.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a synthetic resin lining pipe adhesive composition suitable for producing a synthetic resin lining pipe obtained by adhering a synthetic resin pipe to an inner surface of a metal pipe with an adhesive. TECHNICAL FIELD The present invention relates to an adhesive composition for a synthetic resin lining pipe, which makes it possible to obtain a synthetic resin lining pipe having excellent properties.

[0002]

2. Description of the Related Art Conventionally, a synthetic resin lining pipe has been manufactured by a method called an expansion method or a contraction method.

In the swelling method, an adhesive is interposed between the outer peripheral surface of the synthetic resin tube and the inner peripheral surface of the metal tube, and the inside of the synthetic resin tube is swelled by heating and pressurizing to bond the two. (For example, JP-A-56-55227 and JP-A-58-12720). On the other hand, in the diameter reduction method, the diameter of the metal pipe is reduced by a roll or the like with an adhesive agent interposed between the outer peripheral surface of the synthetic resin pipe and the inner peripheral surface of the metal pipe, whereby the outer periphery of the synthetic resin pipe is reduced. The surface and the inner peripheral surface of the metal tube are pressure-bonded to each other.

Incidentally, liquids of various temperatures may pass through the synthetic resin lining pipe depending on the application. In particular, when the synthetic resin lining pipe is used for an application in which the temperature of the liquid passing through changes instantaneously, it is necessary that the synthetic resin lining pipe has excellent thermal shock resistance. Therefore, it is required to use an adhesive having excellent heat resistance and thermal shock resistance as the adhesive for obtaining the synthetic resin lining pipe.

On the other hand, as an adhesive for a synthetic resin lining pipe capable of improving heat resistance as described above, a hot melt type adhesive using a thermoplastic resin such as polyamide or polyester has been proposed (JP-A-56). -55227 publication).

Further, as a synthetic resin lining pipe adhesive, a butadiene-styrene block copolymer elastomer hot-melt adhesive (Japanese Patent Laid-Open No. 50-12720).
Gazette) or an adhesive containing a polyolefin obtained by copolymerizing an unsaturated aliphatic carboxylic acid or an anhydride thereof.

On the other hand, although it has been proposed as a hot melt type adhesive for adhering metals to each other, a carboxyl group-containing polyester resin is mixed with an epoxy resin and a curing agent as an adhesive excellent in heat resistance. ,
Reaction-curable polyester hot-melt adhesives that are heated and crosslinked are known (Adhesive Ag).
e Vol. 33, No. 12, pp. 32-36 (199
0)). Here, an epoxy resin and a carboxyl group-containing saturated polyester resin are pre-reacted at a high temperature for a long time, and a nitrogen-containing compound such as dicyandiand is used as a curing agent for curing the composition. Since this adhesive is a hot-melt type adhesive, it is not necessary to use a solvent, and the heat resistance can be improved as compared with the hot-melt type adhesive made of a thermoplastic resin.

[0008]

However, in the synthetic resin lining pipe obtained by using the conventional adhesive for synthetic resin lining pipe as described above, the durable adhesion between the synthetic resin pipe and the metal pipe is not sufficient. There was a problem. That is, when the obtained synthetic resin lining pipe was repeatedly subjected to the cooling / heating cycle test, there was a problem that the synthetic resin pipe and the metal pipe were liable to be peeled at the bonded portion, and the thermal shock resistance was not sufficient. In particular, when a hot-melt type adhesive made of a thermoplastic resin is used, it is desirable that the viscosity be as low as possible at the lowest temperature in order to obtain the fluidity required for the application of the adhesive, but at the same time the heat resistance decreases. However, it cannot be used for a synthetic resin lining pipe through which a high temperature fluid passes.

Further, when a solvent volatilization type adhesive is used as the adhesive, there are problems that the working environment is contaminated by the organic solvent, and many steps and working spaces for drying the solvent are required. It was

On the other hand, it is considered that the epoxy resin-carboxyl group-containing saturated polyester resin-based hot-melt type adhesive agent for adhering the above-mentioned metals improves the heat resistance of the cured adhesive. However, in order to cure this composition, a nitrogen-containing compound such as dicyandiamide, an imidazole compound or a urea compound must be used as a curing accelerator. Therefore, when the lining resin in the synthetic resin lining tube is made of a chlorine-containing resin, the chlorine-containing resin is deteriorated because the dechlorination reaction and the dehydrochlorination reaction of the chlorine-containing resin are accelerated with heating. there were.

An adhesive system composed of an epoxy resin and a saturated polyester resin containing a carboxyl group is excellent in flexibility near room temperature and a cured product having a high elongation rate can be obtained, but it is low in a high temperature region. Since it breaks at an elongation rate, it is considered that when the synthetic resin lining pipe is subjected to a thermal shock from a high temperature to a low temperature or from a low temperature to a high temperature, peeling is likely to occur at the bonded portion.

It is an object of the present invention to obtain a synthetic resin lining pipe which is excellent in durable adhesiveness, especially in thermal shock resistance, even when lining a metal pipe with a chlorine-containing resin such as vinyl chloride resin. An object of the present invention is to provide an adhesive composition for a synthetic resin lining pipe, which enables the adhesive.

[0013]

Means for Solving the Problems As a result of intensive studies to achieve the above object, the inventors of the present invention have found that an epoxy group-containing compound and a polyolefin resin powder having a specific particle size are used for a specific saturated polyester resin. A synthetic resin lining tube having excellent thermal shock resistance can be obtained by compounding the epoxy group-containing compound having a specific ratio of an epoxy group-containing compound having 3 or 4 epoxy groups in the molecule. Found that an adhesive composition suitable for
The present invention has been accomplished.

That is, the synthetic resin lining pipe adhesive composition according to claim 1 has a carboxyl group equivalent of 30.
0 to 4000 and weight average molecular weight of 1000 to 60
For 100 parts by weight of saturated polyester resin of 00,
5 to 50 parts by weight of an epoxy group-containing compound and 1 to 50 of a polyolefin resin powder having an average particle size of 1 to 100 μm
Part by weight, so that the compound having 3 or 4 epoxy groups in the molecule in the epoxy group-containing compound is 10 mol% or more based on the total of the saturated polyester resin and the epoxy group-containing compound. It is an adhesive composition for synthetic resin lining pipes contained.

The details of the adhesive composition for a synthetic resin lining pipe of the present invention will be described below. The saturated polyester resin used in the adhesive composition of the present invention has a carboxyl group equivalent of 300 to 4000 and a weight average molecular weight of 10
00-6000, and the main chain is essentially (R-COO
-) Is a saturated polyester resin having an ester bond (in the formula, R represents a divalent hydrocarbon group).

The carboxyl group equivalent is less than 300,
When the weight average molecular weight is less than 1000, the cross-linking density of the final cured product becomes high and the elastic modulus of the cured product becomes too high, so that the adhesive stress is likely to occur due to the thermal stress applied to the lining pipe.

On the other hand, when the carboxyl group equivalent is more than 4000 and the weight average molecular weight is more than 6000, the crosslink density becomes too low, the heat resistance of the cured product is lowered, and the heat applied to the lining pipe also causes adhesive peeling. Occurs.

Examples of the epoxy group-containing compound used in the adhesive composition of the present invention include bisphenol type epoxy resin, novolac type epoxy resin, aliphatic epoxy resin, alicyclic epoxy resin, and the like.
They may be used alone or in combination of two or more.

The above-mentioned epoxy group-containing compound is added in order to extend the main chain of the polyester resin and increase the elongation at break of the cured product. The epoxy group-containing compound is 5 to 5 with respect to 100 parts by weight of the saturated polyester resin.
When the content is less than 5 parts by weight, the saturated polyester resin which does not participate in the reaction remains in the system when the content is less than 5 parts by weight, and conversely 50 parts by weight is added.
This is because when the amount is more than parts by weight, the epoxy group-containing compound that does not participate in the reaction remains, and in any case, the heat resistance and water resistance decrease.

The epoxy group-containing compound must be blended in the above proportion, of which 3 or 4 are included in the molecule.
The epoxy group-containing compound having one epoxy group must be contained so as to account for 10 mol% or more in the total resin content. This is because if it is less than 10 mol%, the degree of crosslinking becomes too small and the heat resistance becomes insufficient. The number of moles in this case is calculated based on the weight average molecular weight.

When an epoxy group-containing compound having 5 or more epoxy groups in the molecule is used, the crosslink density becomes too high, and the elastic modulus of the cured product becomes too high.
The thermal shock resistance of the bonded product decreases. Therefore, it is preferable not to include an epoxy group-containing compound having 5 or more epoxy groups in the molecule. Even if the compound containing 5 or more epoxy groups is contained in the molecule, it is preferably suppressed to 1 mol% or less based on the total of the saturated polyester resin and the epoxy group-containing compound.

Examples of the epoxy group-containing compound containing 3 or 4 epoxy groups in the molecule include:
Trimethylolpropane triglycidyl ether, tetrakis (glycidyloxyphenyl) ethane, triglycidyl (trishydroxyethyl) isocyanate, glycerol triglycidyl ether, sorbitol triglycidyl ether, sorbitol tetraglycidyl ether, pentaerythritol triglycidyl ether,
Examples thereof include pentaerythritol tetraglycidyl ether, diglycerol triglycidyl ether, tris (glycidyloxyphenyl) methane, phenol novolac type epoxy resins having a polymerization degree of 3 and 4, cresol novolac type epoxy resins having a polymerization degree of 3 and 4. These epoxy group-containing compounds may be used alone or as a mixture of two or more kinds.

In the adhesive composition of the present invention, the above-mentioned polyolefin resin powder having an average particle size of 1 to 100 μm is blended. The polyolefin resin powder is blended in order to improve the thermal shock resistance. Has been done. Average particle size is 1μ
If it is less than m, the effect of improving the thermal shock resistance cannot be sufficiently obtained, and if it exceeds 100 μm, the cured product becomes brittle, breaks at a low extension rate, and the amount of adhesive applied increases, which is disadvantageous in terms of cost. .

The polyolefin resin powder is blended in a ratio of 1 to 50 parts by weight with respect to 100 parts by weight of the saturated polyester resin. This is because if the amount is more than 10 parts, the cured product becomes too brittle and breaks at a low elongation.

As the above-mentioned polyolefin resin powder,
For example, polyethylene (low density polyethylene, linear low density polyethylene) resin, ethylene-vinyl acetate copolymer resin, polypropylene resin, or a resin obtained by partially modifying these resins, or two or more of these resins. A mixture of

The synthetic resin lining pipe adhesive composition of the present invention comprises the above saturated polyester resin, epoxy group-containing compound and polyolefin resin powder in the above proportions. Known curing accelerators, anti-settling agents, colorants and the like may be added as long as the purpose is not impaired.

As the curing accelerator, chromium (III) hexanoate, chromium (III) pentanoate, chromium (III) butyrate, and chromium (II) 2-ethylhexanoate (II) are used.
I), chromium (III) decanoate, chromium (III) oleate, chromium (III) stearate, chromium (III) toluate, chromium (III) cresolate,
Chromium (III) tricarboxylate compounds such as chromium (III) benzoate, chromium (III) alkyl benzoate, chromium (III) alkoxy benzoate, chromium (III) naphthenate, and chromium (III) alkoxide, di-isopropoxy Bis (acetylacetonate)
Titanium, isopropoxy (2-ethylhexanediolato) titanium, di-n-butoxy-bis (triethanolaminato) titanium, hydroxybis (lactate) titanium, titanium chelate compound, triphenylphosphine, aluminum (III) acetyl Acetonates and the like are included, but are not limited thereto.

[0028]

In the adhesive composition for a synthetic resin lining pipe of the present invention, the epoxy group-containing compound is blended in the above specific saturated polyester resin in the above specific ratio, and 3
The epoxy group-containing compound having 4 or 4 epoxy groups is blended so as to account for 10 mol% or more with respect to the total of the saturated polyester resin and the epoxy group-containing compound. Properties, especially thermal shock resistance.

Further, since the polyolefin resin powder having the above-mentioned specific particle size is blended in the above-mentioned specific ratio, the expansion ratio at high temperature is increased by the polyolefin-based resin powder, which also results in heat resistance. Impact resistance is enhanced.

[0030]

The present invention will be clarified by describing non-limiting examples of the present invention. In the following description, “part” means “part by weight” unless otherwise specified.

Adhesive compositions of formulation examples 1 to 11 shown in Table 1 below were prepared.

[0032]

[Table 1]

Details of the components in Table 1 are as follows. Saturated polyester resin ... Product name by Hughes Company: Dyn
Acoll 8330, average molecular weight 4000, carboxyl group equivalent 2000-3000).

Tactics 742 ... Semi-solid trifunctional epoxy resin compound manufactured by Dow Chemical Japan, epoxy equivalent =
160. Accelerator AMC-2 ... Chromium (III) tricarboxylate (manufactured by Aerojet General Corporation.

FLOWCENS UF-1,5 ... Low density polyethylene, low density polyethylene manufactured by Sumitomo Seika Chemical Co., Ltd., having a medium particle size of about 25 μm and a Vicat softening point of 96 ° C. FLOWCEN UF-80 ... Low-density polyethylene manufactured by Sumitomo Seika Co., Ltd. with a medium particle size of 25 μm and a Vicat softening point of 76 ° C.

Flowback D-5020 ... Medium particle size of about 5
An ethylene-vinyl acetate copolymer manufactured by Sumitomo Seika Co., Ltd., which has a 0 μm and Vicat softening point of 56 ° C. Floblene B-200 ... Sumitomo Seika Chemical Co., Ltd. polypropylene with a medium particle size of about 80 μm and a Vicat softening point of 155 °.

Techpolymer MBX-5 ... Medium particle size of about 5 μ
m cross-linked polymethylmethacrylate manufactured by Sekisui Plastics Co., Ltd. Techpolymer SBX-6 ... Cross-linked polystyrene manufactured by Sekisui Plastics with a medium particle size of about 6 μm.

Shilton AMT-50 ... Medium particle size of about 6 μm
Mizusawa Chemical Industry aluminosilicate. In the above-mentioned formulation examples 1 to 11, the respective components were blended in the above-mentioned predetermined proportions and mixed to prepare.

Using the adhesive compositions of Formulation Examples 1 to 11 obtained as described above, the following Experimental Examples 1 and 2 were carried out to evaluate each adhesive composition. Experimental Example 1 0.5 g of each adhesive of Formulation Examples 1 to 11 was added to 125 mm x 2
Apply to a 5 mm x 1.6 mm mild steel plate and overlay canvas (No. 9) (overlay area is 25 x 100 mm), 1
It was heat-cured at a temperature of 20 ° C. for 40 minutes to obtain an adhesive test piece. Using this adhesive test piece, 90 ° peel strength was measured at 25 ° C. at a pulling speed of 50 mm / min. Also,
The same adhesion test piece was immersed in hot water at 85 ° C for 7 days, dried, and then pulled at 25 ° C at a pulling speed of 50 mm.
The 90 ° peel strength was measured in 1 / min. The results are shown in Table 2 below.

[0040]

[Table 2]

As is clear from Table 2, in the formulation example 6 in which the polyolefin resin powder is not blended and the formulation example 7 in which the blending ratio of the polyolefin resin powder is too low, sufficient peeling strength (adhesive strength) is obtained. Was not obtained, and it was naturally peeled off after immersion in hot water. Similarly, in the blending example 8 in which the blending ratio of the polyolefin-based resin powder was too high, the peel strength after immersion in hot water was remarkably reduced. Furthermore, in the formulation examples 10 and 11 prepared by blending resin powders other than the polyolefin resin powder, the peel strength after immersion in hot water was considerably lowered.

On the other hand, formulation example 1 corresponding to the example
In Nos. 6 to 6, not only the initial peel strength was high, but also the peel strength after immersion in hot water showed a sufficient value. Experimental Example 2 The adhesives of Formulation Examples 1 to 11 were applied to the outer peripheral surface of a chlorinated vinyl chloride resin tube having an outer diameter of 54.4 mm x an inner diameter of 48.4 mm x a length of 300 mm to a thickness of 100 µm. Next, a chlorinated vinyl chloride resin tube coated with an adhesive was used to form an outer diameter of 63.
5mm, thickness 3.5mm and inner diameter 56.5mm inserted into the steel pipe, the outer diameter of the steel pipe is 60.5mm
The diameter was reduced so that Then, the reduced diameter synthetic resin lining steel pipe was put into an oven at 80 ° C., taken out 60 minutes later, and allowed to cool at room temperature to obtain a synthetic resin lining steel pipe.

The synthetic resin-lined steel pipe thus obtained was
A step of immersing in water at 85 ° C. for 5 minutes and immediately after immersing in hot water at 85 ° C. for 5 minutes was defined as one cycle, and after 300 cycles, a cylindrical portion having a length of 2 cm was cut from the end of the synthetic resin lining steel pipe. Then, after drying the cylindrical portion, it is divided into 12 equal parts in the circumferential direction to obtain divided pieces (divided pieces No. 1 to 12 in Table 3 described later), and the shear strength of the adhesive portion of each divided piece is set to 25. At a loading rate of 20 kg /
Measured in seconds. Further, also for the synthetic resin lining steel pipe before the thermal cycle test, to obtain a test piece in the same manner,
Shear strength was measured. The results are shown in Table 3 below.

[0044]

[Table 3]

As is clear from Table 3, Formulation Examples 6-11
Then, there is a portion that is not bonded in the circumferential direction after the number of cooling and heating cycles is 300 cycles, and in the case of using the formulation examples 8 and 10, a portion that is not bonded in the circumferential direction even before the cooling and heating cycle. Was recognized. On the other hand, in the formulation examples 1 to 5 corresponding to the examples, there was almost no variation in the adhesive strength in the circumferential direction before the thermal cycle test, and sufficient adhesive strength was exhibited.
Further, even after 300 cycles of the cooling / heating cycle, the adhesive strength in the circumferential direction does not vary so much.

[0046]

According to the present invention, the above-mentioned specific saturated polyester resin is used as a main component, and the epoxy group-containing compound and the polyolefin resin powder having the above-mentioned specific particle size are blended in the above-mentioned specific ratio. The epoxy group-containing compound contains an epoxy group-containing compound having 3 or 4 epoxy groups in the molecule in an amount of 10 mol% or more based on the total amount of the saturated polyester resin and the epoxy group-containing compound. Therefore, heat-curing and thermal shock resistance of the cured product can be effectively enhanced by heat-crosslinking curing.

In addition, the adhesive composition of the present invention does not accelerate the dechlorination reaction or the dehydrochlorination reaction of the chlorine-containing resin as it is cured by heat crosslinking. Therefore, it becomes possible to provide a heat-resistant adhesive most suitable for applying a synthetic resin lining to a metal tube using a chlorine-containing resin such as a vinyl chloride resin.

Claims (1)

[Claims] 1. The carboxyl group equivalent is 300 to 4000.
And 5 to 50 parts by weight of the epoxy group-containing compound and 100 to 100 parts by weight of the saturated polyester resin having a weight average molecular weight of 1000 to 6000, and an average particle size of 1 to 100 μm.
1 to 50 parts by weight of the polyolefin resin powder of m is mixed, and the compound having 3 or 4 epoxy groups in the molecule in the epoxy group-containing compound is the sum of the saturated polyester resin and the epoxy group-containing compound. To 10 mol%
An adhesive composition for a synthetic resin lining pipe, which is contained as described above.