JPH04309589A - Pipe sealant - Google Patents

Abstract

PURPOSE:To obtain a pipe sealant which is excellent in water pressure resistance and capable of reliable liquid-tight sealing of pipe joints regardless of the nonuniformity of the shape of the pipe joints and the variation of the length of the screws. CONSTITUTION:The pipe sealant comprises 100 pts.wt. thermoplastic elastomer comprising a styrene block copolymer, 100-1,000 pts.wt. organic solvent, a highly water-absorptive polymer, 20-200 pts.wt. tackifying resin and 100 pts.wt. or less inorganic filler.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention relates to a pipe sealing agent used to liquid-tightly seal a connection part when connecting metal pipes, etc., and in particular, the present invention relates to a pipe sealing agent used to liquid-tightly seal a connection part when connecting metal pipes, etc. The present invention relates to a pipe sealant that is difficult to cause and has excellent water pressure resistance.

0002

2. Description of the Related Art When installing water pipes or hot water supply pipes, the pipes are often cut depending on the conditions at the construction site and then connected to other pipes using pipe joints. In water pipes and hot water pipes, a large amount of fluid flows inside the pipes. Therefore, it is necessary to provide a liquid-tight seal at the pipe connection, and as a sealing agent to achieve such a liquid-tight seal, vinyl chloride-vinyl acetate copolymer, alkyd resin, or vinyl acetate, organic solvent, inorganic or Pipe sealants containing organic fillers, plasticizers, etc. are known (for example, Japanese Patent Publication No. 59-37035).
.

[0003] Furthermore, a ring made of hard synthetic resin is attached between the outer peripheral surface of the cut end of the pipe and the inner peripheral surface of the pipe joint, and the ring is attached to the outer peripheral surface of the pipe end and the inner peripheral surface of the pipe joint. There is also a known structure that achieves a liquid-tight seal by bringing it into close contact with a surface (for example, Japanese Utility Model Publication No. 12309/1983).

0004

However, in the former pipe sealing agent, the main components, vinyl chloride-vinyl acetate copolymer, alkyd resin, or vinyl acetate, are relatively hard and do not have sufficient elasticity. Therefore, if stress or displacement occurs on the constructed pipe connection due to abnormal water pressure, etc., the sealant may solidify and the coating film formed may crack, or the bond between the coating film and the pipe may crack. Breakages were likely to occur, with the result that fluid could leak from the pipe connections.

[0005] In the latter liquid-tight seal using a ring, the adhesion between the ring and the pipe is ensured only by mechanical contact. Therefore, if the shape of the cut end of the pipe varies during piping work, or the length of the thread formed at the end of the pipe changes, the adhesion between the ring and the pipe may become incomplete. As a result, fluid leakage may also occur at the pipe connections. An object of the present invention is to provide a pipe sealing agent that has excellent water pressure resistance and is capable of reliably liquid-tightly sealing pipe connections regardless of variations in the shape of the end of the pipe or the length of the threaded part. Our goal is to provide the following.

[0006]

[Means for Solving the Problems] As a result of intensive studies aimed at achieving the above-mentioned problems, the inventors of the present application have devised a method for constructing a pipe sealant described below using a thermoplastic elastomer made of a styrene-based block copolymer as a base polymer. For example, the present inventors have discovered that it is possible to obtain a pipe sealant that has excellent water pressure resistance and exhibits excellent liquid-tight sealing properties regardless of variations in the shape of the pipe end or the length of the threaded part, and has thus achieved the present invention. .

That is, the present invention comprises a thermoplastic elastomer made of a styrenic block copolymer, an organic solvent, a super absorbent polymer, a tackifying resin, and an inorganic filler, and 100 parts by weight of the thermoplastic elastomer. For,
100 to 1000 parts by weight of organic solvent, 20 to 1000 parts by weight of tackifying resin
It is characterized by being blended in a ratio of 200 parts by weight or less and 300 parts by weight of the inorganic filler.

The configuration of the present invention will be explained in more detail below. Components to be Blend In the present invention, a thermoplastic elastomer made of a styrene block copolymer is used as the base polymer. Examples of thermoplastic elastomers made of such styrene block copolymers include styrene-butadiene-styrene block copolymers (SBS),
Styrene-isoprene-styrene block copolymer (S
IS) and styrene-ethylene-butylene-styrene block copolymer (SEBS). These block copolymers consist of end blocks made of polystyrene and intermediate blocks made of rubber, and the end blocks made of polystyrene act as physical crosslinking points (domains).
The intermediate block made of rubber exhibits rubber elasticity.

In the present invention, an organic solvent is blended in order to dissolve the thermoplastic elastomer and soluble components. The organic solvent that can be used is not particularly limited as long as it can dissolve the thermoplastic elastomer. Preferred organic solvents include, for example, toluene, xylene, isopropanol, and the like, and one or more of these preferred organic solvents can be used in an appropriate combination. In the present invention, a super absorbent polymer is blended in order to further improve water stopping properties. Superabsorbent polymers that can be used include, for example, polyacrylate-based, starch-acrylate graft polymer-based, vinyl acetate-acrylic acid copolymer-based, isobutylene-maleic acid copolymer-based, polyvinyl alcohol-based, or carboxymethylcellulose-based. Examples of known superabsorbent polymers include.

Furthermore, in the pipe sealing agent of the present invention, a tackifier resin is blended in order to improve the adhesiveness of the thermoplastic elastomer. As the tackifying resin, conventionally known tackifying resins such as rosin ester and terpene resin can be used. Further, in the pipe sealing agent of the present invention, an inorganic filler is added in order to increase the proportion of nonvolatile content and improve sealing performance. Examples of inorganic fillers that can be used include inorganic powders such as talc, calcium carbonate, mica, kaolin, or clay, and bentonite or silica as a thixotropic agent.

Compounding ratio In the pipe sealing agent of the present invention, the organic solvent is contained in an amount of 100 to 1000 parts by weight per 100 parts by weight of the thermoplastic elastomer.
It is blended within the range of parts by weight. The blending ratio of organic solvent is 10
If it is less than 0 parts by weight, the viscosity of the mixture will be high and the application work will be very difficult. If it is more than 1000 parts by weight, the viscosity will be too low and the applied sealant will run or drip. This is because the amount of coating required for a liquid-tight seal cannot be secured.

The superabsorbent polymer is blended in such a proportion that the solidified tube sealant of the present invention has a water absorption expansion coefficient in the range of 30 to 100% by weight. Note that the water absorption expansion coefficient is a value expressed by weight after water absorption/initial weight x 100-100 (%). If the above-mentioned water absorption expansion coefficient is less than 30% by weight, the volumetric expansion will be small and sufficient liquid-tight sealing performance cannot be ensured, and if it exceeds 100% by weight, there is a possibility that excessive sealant will flow into the pipe. increase to an extreme.

The amount of the tackifier resin to be blended varies depending on the type of tackifier resin used, but it is preferably in the range of 20 to 200 parts by weight based on 100 parts by weight of the thermoplastic elastomer. This is because if it is less than 20 parts by weight, sufficient adhesiveness cannot be obtained, and if it exceeds 200 parts by weight, elastomeric properties are lost, resulting in a decrease in cohesive force or an excessive increase in elastic modulus.

The amount of the inorganic filler to be blended is selected within a range that allows the water absorption expansion coefficient of the solidified sealant of the present invention to be within the above-mentioned range. Usually, the inorganic filler is blended in an amount of 300 parts by weight or less with respect to 100 parts by weight of the thermoplastic elastomer. If it exceeds 300 parts by weight, the elastic modulus of the solidified pipe sealant becomes too high, which reduces the ability to follow stress and displacement caused by abnormal water pressure, etc., and also reduces the water absorption expansion coefficient, impairing liquid-tight sealing properties. This is because it will be done.

[0015]

[Function] The pipe sealing agent of the present invention has a certain degree of flexibility because it uses a thermoplastic elastomer made of a styrene block copolymer as a base polymer. Therefore, even if stress or displacement occurs at the constructed pipe connection due to abnormal water pressure, etc., the coating film formed by the solidification of the pipe sealant is unlikely to crack or the bond between the coating film and the pipe is unlikely to break. .

[0016] Also, it contains a super absorbent polymer, which has a structure in which water-soluble polymers having hydrophilic groups such as carboxyl groups are intermolecularly cross-linked, and has a structure of several hundred times its own volume. It is a polymer that absorbs water and swells to form a hydrogel. Even if pressure is applied to the wet hydrogel, the absorbed water will not seep out. In the present invention, by utilizing such properties of the superabsorbent polymer, even if water enters the sealant from the pipe connection part, water absorption expansion prevents further water entry.
This further improves water-stopping properties.

[0017] Furthermore, since an inorganic filler is added,
It is believed that it is possible to further improve the sealing performance by lowering the cohesive force of the thermoplastic elastomer to an appropriate value or by increasing the proportion of nonvolatile matter. Furthermore, by adding various thixotropic agents in addition to inorganic powder as an inorganic filler, it is possible to prevent sedimentation or separation of the inorganic powder and to improve coating workability by imparting thixotropy to the sealant.

[0018]

[Description of Examples] Hereinafter, the present invention will be made clearer by giving examples and comparative examples of the present invention. Examples 1 to 3 By blending the following raw materials in the proportions shown in Table 1,
Pipe sealants of Examples 1 to 3 were prepared.

(1) Thermoplastic elastomer...SBS (manufactured by Shell Chemical Co., Ltd., product name: Kaliflex TR1122)
use. Styrene content is approximately 30% by weight. (2) Super absorbent polymer…sodium polyacrylate (
(manufactured by Arakawa Chemical Co., Ltd., trade name: Arasorb 800F). Average particle size 30-50 μm. Water absorption capacity (deionized water) 150-25
0g/g. (3) Tackifying resin...Terpene resin (manufactured by Yasuhara Chemical Co., Ltd., trade name: YS Resin TO-105). It is an aromatic modified terpene resin with a softening point of 105°C.

(4) Thixotropic agent: Hydrophobic silica (manufactured by Nippon Aerosil Co., Ltd., trade name: R-974). Average particle size approximately 12nm
, specific surface area 170±20 m2/g. (5) Inorganic powder...clay (manufactured by Sanyo Clay Co., Ltd., product name: O
A clay). The average particle size is approximately 15 μm. (6) Organic solvent: A mixture of toluene and isopropanol at a volume ratio of 9:1.

Comparative Examples 1 to 3 Pipe sealants of Comparative Examples 1 to 3 were prepared by blending the above raw materials in the proportions shown in Table 1 below in the same manner as in Examples 1 to 3. In addition, Table 1 also shows the nonvolatile content and water absorption expansion coefficient of each pipe sealant of Examples 1 to 3 and Comparative Examples 1 to 3.

[0022]

[Table 1]

Examples 1-3 prepared as above
A water pressure test of each of the pipe sealants of Comparative Examples 1 to 3 was conducted in the following manner. Water pressure test After forming a male thread on the outer peripheral surface of the connecting end of a steel pipe with a diameter of 5.08 cm (2 inches) and applying the above pipe sealant to the male thread with a brush, immediately attach the male thread to the pipe fitting. It was screwed into the internally threaded portion of the inner circumferential surface with a torque of 1000 kg·cm and left at room temperature for 24 hours. After that, the water pressure inside the steel pipe was increased to 5, 10, 17.5, 35 and 50k.
The liquid-tight sealing property against high water pressure was investigated by increasing the pressure to g/cm2 and observing the presence or absence of water leakage at the connection portion. In addition, for each of the pipe sealants of Examples and Comparative Examples, the above-mentioned connection parts were formed at 20 locations, and the above-mentioned sealing properties were evaluated. The results are shown in Table 2.

[0024]

[Table 2]

In Table 2, the denominator indicates the number of connections, and the numerator indicates the number of connections where no water leakage occurred. As is clear from Table 2, when each of the pipe sealants of Examples 1 to 3 was used, no water leakage occurred at any of the connection parts. On the other hand, in the pipe sealants of Comparative Examples 1 to 3, water leakage occurred at some connection parts as the water pressure increased.

In Examples 1 to 3 above, sodium polyacrylate was used as the water-absorbing polymer, but instead of the sodium polyacrylate, starch-acrylate graft polymer (manufactured by Sanyo Kasei Co., Ltd., trade name) was used. : Sunwet IM-1000MPS, water absorption capacity (deionized water) 1
000g/g, average particle size 20-50μm) or acrylic acid-vinyl alcohol copolymer (manufactured by Sumitomo Chemical Co., Ltd., product name: Sumikagel SP-520, water absorption capacity (deionized water) 6
00 g/g, average particle size 20 μm) may be used.

[0027]

As described above, according to the present invention, a thermoplastic elastomer made of a styrene block copolymer is used as a base, and an organic solvent, a superabsorbent polymer, a tackifying resin, and an inorganic filler are added to the thermoplastic elastomer as described above. Since they are blended in a specific ratio, it is possible to provide a pipe sealing agent with excellent liquid-tight sealing properties. In other words, when using the pipe sealant of the present invention, even if stress or displacement occurs at the pipe connection due to abnormal water pressure, cracks in the solidified sealant or destruction of the adhesive between the sealant and the pipe will not occur. Hard to occur.

In addition, in the conventional example using a ring, it was difficult to achieve a good liquid-tight seal due to variations in the shape of the tube ends and variations in the length of the threaded portion, but in the present invention, the tube sealant is applied to the tube connection portion. Because it achieves a liquid-tight seal by applying it to the pipe and solidifying it, it reliably seals the pipe connection part liquid-tight, regardless of variations in the shape of the pipe end or the length of the threaded part. Can be done.

Claims (1)

[Claims] 1. A thermoplastic elastomer made of a styrenic block copolymer, an organic solvent, a super absorbent polymer, a tackifying resin, and an inorganic filler, and based on 100 parts by weight of the thermoplastic elastomer, organic solvent 100
A pipe sealing agent containing up to 1,000 parts by weight of a tackifying resin, 20 to 200 parts by weight of a tackifying resin, and 300 parts by weight or less of an inorganic filler.