JP2008069869A - Seal material composition and precoat type seal material - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a seal material composition to be used for precoating a screw portion combining improved constructing efficiency and sealing performance, particularly, initial sealing performance, and to provide a precoat type seal material formed by precoating the screw portion. <P>SOLUTION: The seal material composition to be used for precoating the screw portion comprises (A) reactive liquid resin having cross-linkable reactive groups in molecules and adapted to be cross-linked to form gel hardened material, (B) catalyst and/or hardening agent for cross-linking the (A) component, and (C) water absorbing and swelling component. The precoat type seal material is formed by precoating the screw portion with the seal material composition comprising (A)-(C). A further preferable result is obtained by adding (D) organic resin powder to (A)-(C). <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  TECHNICAL FIELD The present invention relates to a sealing material composition used by pre-coating a threaded portion such as a threaded joint, and a pre-coated sealing material pre-coated on a threaded portion.

  Conventionally, in a pipe such as a water supply pipe or a drain pipe, a joint is used when connecting pipes and pipes, or when connecting pipes such as water heaters and valves. In particular, nipples, sockets, elbows, crosses, union joints, etc. are used as threaded joints that are fastened by screws. Threaded joints are connected by screws, i.e., screwing, and a gap is created in the threaded part, and fluid flowing inside the pipe leaks from this part, so it is necessary to use a sealing material in the threaded part to prevent fluid leakage There is. As a sealing material used for such a screw portion, a solid sealing material such as a sealing tape, a sealing material using a solidifying or curable liquid resin, a sealing material precoated on the screw portion, or the like is used. The sealing material using a solidifying or curable liquid resin is applied to the screw part at the site of use, and the pre-coated sealing material is applied in advance to the screw part and cured. .

  The above-mentioned sealing tape, which is a solid sealing material, is obtained by processing a fluorine resin, a polyethylene resin, or the like into a thin film, and is used by being wound around a screw portion. Since this does not require a special tool or the like for coating, it is excellent in workability. However, in order to exhibit high sealing performance, it is necessary to wrap to a thickness that fills the depth of the screw valley, and the thickness of the sealing material must be increased by increasing the number of windings. Therefore, the screw diameter is increased at the thread portion, and the tightening torque when the threaded joint is fastened to the pipe or the like is increased. For this reason, a fastening tool is required, and special tools are required depending on the types of pipes, water heaters, valves and the like, and there is a drawback that it is difficult to work in a narrow place. Moreover, once the screw joint that was tightened was rotated in the loosening direction, the sealing performance was greatly reduced.

  Further, the sealing material using the above-described solidifying or curable liquid resin is in a liquid state at the time of application, and is solidified or cured after application and fastening. That is, it is applied to a threaded portion of a threaded joint, the threaded joint is fastened to a pipe or the like, and then the sealing material is solidified and hardened to exhibit sealing performance. (The former is solidified and the latter is hardened, and the latter is hardened.) This is a liquid when the screw joint is tightened, so a high tightening torque is required. And has the advantage that it can be tightened relatively easily. Examples of such resins include those obtained by dissolving a rubber component or a plastic component in an organic solvent, moisture curable resins, and heat curable resins. Since the sealing material fills the gaps in the threaded portion and is solidified and hardened, it exhibits high sealing performance. On the other hand, it has a high adhesive force with the threaded portion, so extremely high torque is required when removing the threaded joint. is necessary. In particular, it is difficult to remove things that have passed for a long time since construction, and sometimes the equipment is destroyed. In addition, since it is used by directly applying to the screw part at the site, if the application amount is insufficient or there is uneven application, the sealing performance will not be demonstrated and leakage will occur, There is also a problem that depends on the skill level of the worker.

  The above-mentioned sealing material pre-coated on the threaded part is a form that is pre-applied to the threaded part and solidified or cured, and is constant regardless of the skill level and technical skills of the workers at the pipe fastening site. The sealing property can be exhibited. The seal material to be pre-coated is a material in which a threaded portion is coated with a polyamide resin or an acrylic resin by solvent evaporation, curing, melting, or the like. However, as in the case of the sealing tape described above, in order for the pre-coated resin to be sufficiently filled in the gaps in the screw portion, the thickness of the sealing material by the resin must be increased, and a high tightening torque is required. It has the same disadvantage of being necessary.

  On the other hand, Patent Document 1 discloses a gel-like sealing material. This is a method in which a gel-like sealing material molded in a string shape is wound around a threaded portion of a pipe or a threaded joint and fastened to fill a gap in the threaded portion and exhibit sealing performance. The gel sealant is softer and easier to change the shape than the above-mentioned solidifying, curable sealant, or precoat type sealant, so the tightening torque required for fastening is low and the torque is low when removing. It can be removed. However, since the gel-like sealing material is not bonded to the threaded portion, it peels off from the threaded portion due to the stress generated by the rotation during fastening, or the gel-like sealing material breaks due to the low resin strength. As a result, there is a problem that the sealing performance is deteriorated. In particular, the gel-like sealing material behaves to return to its original state when a tension is applied. In Patent Document 1, using this behavior, the gel-like sealing material is wound while applying tension, and the gel-like sealing material is “returned to the previous state” after fastening, thereby filling the gap of the screw portion. It is said. However, if the gel-like sealing material is ruptured when fastening the threaded joint, it moves so that the tension is restored in both directions from the ruptured portion, and there is a sealing material around the ruptured portion. There was a drawback of disappearing.

Further, Patent Document 2 discloses a watertight precoat type sealing material comprising a combination of a non-reactive sealing material and a water-absorbing swelling resin. However, this requires a high tightening force as described above. Further, although a water-swellable substance is contained, it takes time until the water swells after contact with water, and the sealing effect during that time is low, causing an initial leakage. In addition, the swellable material that gradually swelled flows out together with the leakage of the fluid, and a high sealing effect cannot be expected.
JP 2000-291851 A Japanese Patent Laid-Open No. 5-186863

  An object of the present invention is to solve the problems of the threaded portion seal such as the above-described threaded joint, and to provide a sealing material composition and a precoat type sealing material having excellent workability and sealing performance, particularly initial sealing performance. It is to provide.

  As a result of intensive studies to solve the above-mentioned problems, the present inventors have (A) a reactive liquid resin having a crosslinkable reactive group in the molecule to be a gel-like cured product by crosslinking, (B) the component (A). The present invention has led to the development of a sealing material composition that is pre-coated on a threaded portion comprising a catalyst and / or a curing agent that crosslinks and / or a curing agent and (C) a water-swelling component. Further, the present invention provides a precoat type sealing material in which the sealing material composition comprising the above (A) to (C) is precoated on the screw portion. Furthermore, when (D) organic resin powder is further added to the above (A) to (C), more preferable results are obtained.

  Hereinafter, the present invention will be described in more detail. The component (A) used in the present invention is a reactive liquid resin that has a crosslinkable reactive group in the molecule and becomes a gel-like cured product by crosslinking. The component (A) is liquid before the reaction, that is, before crosslinking, and is cured by the crosslinking reaction of the crosslinkable reactive group to form a gel-like cured product. Here, the gel form referred to in the present invention has a shape retaining property because it is three-dimensionally crosslinked, but is soft and easily deformed when an external force is applied. Specifically, according to JIS K6301 In rubber hardness measurement, the measured value (rubber hardness value) cannot be measured (becomes 0), and the hardness is so low that it is soft. The penetration according to JIS K2220 (1/4 cone, total weight 9.38 g) The tensile strength of JIS K6251 is 0.01 to 1 MPa.

  The component (A) has a reactive group in the molecule, that is, at the molecular end or side chain, and changes from a liquid state to a gel state when the crosslinkable reactive group is crosslinked. Examples of the crosslinkable reactive group include a (meth) acryloyl group, an epoxy group, a hydrolyzable silane, and a vinyl group-containing silane. More specifically, the hydrolyzable silane is a silane having an alkoxy group such as a methoxy group, an ethoxy group or a propoxy group; a silane having an alkenyloxy group such as an isopropenyloxy group or a 1-ethyl-2-methylvinyloxy group. A silane having an amino group such as a dimethylamino group, a diethylamino group, a butylamino group or a cyclohexylamino group; a silane having an aminoxy group such as a dimethylaminoxy group or a diethylaminoxy group; an acetoxy group, an octanoyloxy group or a benzoyloxy group; Silanes having an acyloxy group such as: silanes having a ketoxime group such as a dimethyl ketoxime group, a methyl ethyl ketoxime group, and a diethyl ketoxime group. The vinyl group-containing silane undergoes a hydrosilylation reaction, and is an addition reaction between silicon having a vinyl group and silicon having a hydrogen atom. In this case, the component (A) is a compound having a vinyl group-containing silane as a crosslinkable reactive group, and further requires a compound having a silane having a hydrogen atom.

  The main chain skeleton portion of the component (A) is not particularly limited as long as the cured product exhibits a gel shape, and examples thereof include organopolysiloxane, a polymer polymerized by a polyether bond, and a polymer polymerized by a polyurethane bond. . Among these, organopolysiloxanes having good elongation characteristics and impact absorption, low elastic modulus, low stress and little oil bleed over time are preferable.

  The present invention may contain a plasticizer in addition to the component (A). Preferred plasticizers include dimethylpolysiloxane, phthalic acid ester, adipic acid ester, epoxy, polyester, phosphoric acid, and fatty acid. When organopolysiloxane is selected as the component (A), it is preferable to select dimethylpolysiloxane as the plasticizer.

  The main chain skeleton of the preferred component (A) of the present invention is organopolysiloxane, and the main chain skeleton described in JP-A-6-184257 is particularly preferable. The possible reactive group of component (A) is preferably a (meth) acryloyl group or a vinyl group-containing silane.

  Component (B) of the present invention is a catalyst or a curing agent for causing a crosslinking reaction of the crosslinkable reactive group of component (A) described above. The catalyst itself is a component that does not change itself and promotes the crosslinking reaction, and the curing agent is a component that self-confidently becomes a bond or emits ions or unpaired electrons to crosslink the crosslinkable reactive group. is there. Specifically, when the aforementioned reactive group is a (meth) acryloyl group, an organic peroxide or a photoinitiator can be used as a curing agent. Moreover, when the above-mentioned reactive group is an epoxy group, amines, acid anhydrides, phenols and the like can be used as curing agents. When the reactive group is a hydrolyzable silane, an organometallic compound can be used as a catalyst. Further, when a vinyl group-containing silane is used, an organometallic compound can be used as a catalyst, and a silane compound having a hydrogen atom as a curing agent can be used. is there.

  Exemplifying the examples of the aforementioned curing agents or catalysts in detail, organic peroxides as curing agents for (meth) acryloyl groups are cumene hydroperoxide, t-butyl hydroperoxide, p-pentane hydroperoxide, methyl ethyl ketone peroxide. Hydroperoxides such as oxides, diallyl peroxides such as dicumyl peroxide, t-butylcumyl peroxide, di-t-butyl peroxide, ketone peroxides such as methyl ethyl ketone peroxide, cyclohexane peroxide, and methylcyclohexane peroxide Oxides, diacyl peroxides such as benzoyl peroxide, lauroyl peroxide acetyl peroxide, t-butyl peroxybenzoate, t-butyl peroxyacetate, t-butyl Organic peroxide peroxy esters of peroxy maleate, and the like. About 1 to 10 parts by weight of the curing agent is added to 100 parts by weight of component (A). By using this hardening | curing agent, (A) component can be made into heat sclerosis | hardenability or two-component mixed sclerosis | hardenability.

  The photoinitiator of the (meth) acryloyl group curing agent generates radical species upon irradiation with light, and includes benzophenone, acetophenone, propiophenone, xanthol, fluorin, benzaldehyde, anthraquinone, triphenylamine, carbazole, 3 -Methylacetophenone, 4-methylacetophenone, 3-pentylacetophenone, 4-methoxyacetophenone, 3-bromoacetophenone, p-diacetylbenzene, 3-methoxybenzophenone, 4-allylacetophenone, 4-chloro-4-benzylbenzophenone, 3- Chloroxanthone, 3,9-dichloroxanthone, 3-chloro-8-nonylxanthone, benzoyl, benzoin methyl ether, bis (4-dimethylaminophenyl) ketone, benzylmethoxy Ketal, 2-chlorothioxatone, 2,4,6-trimethylbenzoyldiphenylphosphine oxide, benzyl, camphorquinone, 3-ketocoumarin, anthraquinone, α-naphthyl, acenaphthene, p, p′-dimethoxybenzyl, p, Carbonyl catalysts such as p'-dichlorobenzyl, thioxanthone catalysts such as 2-chlorothioxanthone, 2-methylthioxanthone, 2,4-diethylthioxanthone, 2,4-dimethylthioxanthone, 2,4 , 6-Trimethylbenzoyldiphenylphosphine oxide, bis (2,6-dimethoxybenzoyl) -2,4,4-trimethyl-pentylphosphine oxide, bis (2,6-dichloro-benzoyl) -4'-n-propyl Phenylphosphine oxide, bis ( It can be used such as 6-dimethyl-benzoyl) acylphosphine oxides such as diphenyl phosphine oxide. About 1 to 10 parts by weight of the curing agent is added to 100 parts by weight of component (A). By using this hardening | curing agent, (A) component can be made photocurable.

  Examples of the catalyst in the case where the reactive group is hydrolyzable silane include iron octoate, iron naphthenate, cobalt octoate, cobalt naphthenate, tin octoate, tin naphthenate, lead octoate and lead naphthenate. Alkyl tin ester compounds such as organic acid metal salts, dibutyl tin diacetate, dibutyl tin dilaurate, dibutyl tin dioctoate, etc., metal alcoholates such as tin halide compounds, tin orthoester compounds, tetrabutyl titanate, tetrabutyl zirconate And titanium chelates such as diisopropoxybis (acetylacetonato) titanium and diisopropoxybis (ethylacetoacetate) titanium, and amines such as ethylhydroxylamine, dimethylhydroxylamine and γ-aminopropyltriethoxysilane That. The amount of the moisture curing catalyst used is preferably 0.01 to 10 parts by weight, particularly 0.1 to 5 parts by weight, based on 100 parts of component (A). By using this catalyst, the component (A) can be made moisture curable.

  The catalyst in the case where the reactive group is a vinyl group-containing silane is a platinum group metal, and the platinum group includes platinum, rhodium, ruthenium, palladium, osmium, and iridium. Specifically, chloroplatinic acid, alcohol-modified chloroplatinic acid, coordination compounds of chloroplatinic acid and olefins, vinyl siloxane or acetylene compounds, tetrakis (triphenylphosphine) palladium, chlorotris (triphenylphosphine) rhodium, etc. Can be mentioned. The addition amount of this catalyst is 0.1-500 ppm as a platinum atom with respect to (A) component, Preferably 1-100 ppm is added. By using this catalyst, the component (A) can be made heat curable or two-component mixed curable.

  The water-absorbing swellable component of the component (C) of the present invention is a component that absorbs water and expands its volume when contacted with water. Typically, a water-soluble electrolyte polymer is introduced with a light crosslinking, and may be either a natural water-swelling resin or a synthetic water-swelling resin. Examples of natural water-swellable resins include starch-based acrylonitrile graft polymer hydrolyzate, starch-acrylic acid graft polymer, cellulose-based acrylonitrile graft polymer, crosslinked carboxymethyl cellulose, etc. Other examples include polysaccharides such as hyaluronic acid and agarose, and proteins such as collagen. Examples of the synthetic water-absorbing swellable resin include polyvinyl alcohol-based polyvinyl alcohol cross-linked polymers, acrylic poly (sodium acrylate cross-linked), sodium acrylate-vinyl alcohol copolymers, etc. Examples of other addition polymers such as a certain polyethylene glycol diacrylate cross-linked polymer include maleic anhydride polymers, vinyl pyrrolidone polymers, and other condensation resins.

  By adding this component, when water comes into contact with the precoat-type sealing material, the precoat-type sealing material swells and sealability can be improved. Component (C) is preferably added in an amount of 5 to 50 parts by weight per 100 parts by weight of component (A). If it is less than 5, the sealing performance is lowered, and if it is more than 50 parts by weight, the physical strength of the pre-coated sealing material of the present invention is lowered and the breaking strength is weakened. More preferably, it is 5-30 weight part.

  In the present invention, (D) organic resin powder can be further added to the components (A) to (C). By adding the component (D), the initial water swelling property of the precoat type sealing material of the present invention is improved. Component (D) organic resin powder includes polyethylene resin powder, polypropylene resin powder, nylon resin powder, ethylene-vinyl acetate copolymer (EVA) resin powder, polyester resin powder, powdered polyethylene and EVA copolymer resin powder, and the like. To mention. (D) The average particle diameter of a component is 5-100 micrometers, Preferably it is 5-25 micrometers.

  Here, as a technique related to a sealing material composition for a pipe joint, it is known to add a component similar to the component (D) of the present invention as a galling inhibitor. However, it has not been known that when this component is added to a composition obtained by adding a water-swelling component to a gel-like sealing material, the initial water-swelling property is improved. That is, when this component is added, as soon as water comes into contact with the precoat-type sealing material of the present invention, the volume swells and the threaded portion can be strongly sealed. When this component is not added, for example, when a fluid flows in the pipe at a high pressure, the precoat type sealing material may be compressed by the pressure of the fluid in the pipe, and a flow path may be formed from a thin portion to leak. However, as soon as this component is added, it expands in volume and sufficiently fills the gaps in the threaded portion, so that initial leakage can be prevented without being pushed by the pressure of the fluid in the pipe. In addition, when the water-swelling component of component (C) comes into contact with water and swells, the compatibility with component (A) decreases, and it becomes easy to detach from the precoat type sealing material, but component (D) is added. This can be prevented.

  The component (D) is not necessarily required when the pressure of the fluid flowing in the pipe is not high, but when the pressure of the fluid is high or when it is necessary to maintain the sealing performance for a long time, the component (A) is 100 weight. It is preferable to add 10 to 300 parts by weight with respect to parts.

  The sealing material composition or precoat type sealing material of the present invention essentially comprises the above-mentioned components (A) to (C), but other components can be added as necessary. For example, a stabilizer, a rust preventive agent, a coloring agent, an adhesion imparting agent, an anti-aging agent, a dispersion aid and the like can be mentioned.

  The sealing material composition of the present invention is used by pre-coating the screw portion in advance. Pre-coating is to apply in advance to a threaded portion such as a threaded joint and form a gel-like cured product by crosslinking, and the gel-like cured product becomes the pre-coated sealing material of the present invention. The sealing material composition before crosslinking is in a liquid state and can be easily applied to the entire circumference of the screw portion. The coating method can be applied by a known method such as brush coating, dipping, discharge coating from a nozzle, or flow coating. After application, the sealing material composition is cured by a crosslinking reaction. The curing method is determined by the structure of the component (A), that is, the type of the crosslinkable reactive group. If it is heat curable, it is heated. If it is photocurable, it is irradiated with light. If present, it is cured by curing in the presence of moisture.

  The sealing material composition before crosslinking is in a liquid state and can be easily applied so as to fill the thread valley of the threaded portion. By being cross-linked in this state, the precoat type sealing material becomes a cured product having a high adhesive force (adhesive force) with the surface constituting the screw valley. On the other hand, when the member to which the precoat type sealing material of the present invention is applied is fastened, it is rotated with a high frictional force between the male screw and the female screw. At this time, the precoat type sealing material of the present invention is a gel-like cured product. Therefore, the surface portion is broken and peeled off as it rotates. Even if this portion is thick, the surface is easily peeled off and discharged as a residue from the threaded portion, so that fastening with a low tightening force is possible. Since the precoat type sealing material of the present invention is a gel-like cured product, the stress required for breaking is reduced, and as a result, the axial force required for fastening can be reduced. In addition, as described above when the precoat type sealing material breaks, it is only the surface layer of the precoat sealing material that breaks, and the lower layer portion is firmly in close contact with the screw valley, so that there is no sealing material in the screw portion. Since there is no place, a highly reliable sealing performance is achieved.

  The sealant composition and precoat type sealant used by precoating the threaded portion of the present invention can be applied to the threaded portion of the threaded joint, and the threaded joint can be applied to nipples, sockets, elbows, crosses, etc. it can. The screw joint can be made of either metal or plastic. The fluid flowing through the pipe is preferably an aqueous liquid.

  Since the precoat type sealant obtained by crosslinking the sealant used by precoating the screw part of the present invention is a gel-like cured product, it can be operated with a low torque at the time of fastening and removal, so a tool is used. The work efficiency can be greatly improved. Moreover, the sealing property is good and leakage can be prevented. In particular, when organic resin powder is added, initial leakage when the water pressure is high can be prevented, and highly reliable sealing performance can be exhibited. That is, the present invention can achieve both good sealing performance and workability at the time of fastening and detachment, which could not be achieved conventionally.

  EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples.

Example 1 (Composition 1)
16.3 g of aminopropyldimethoxysilane was added to 2000 g of terminal silanol polydimethylsiloxane having a molecular weight of about 10,000, and the mixture was stirred and reacted at 100 ° C. for 2 hours while being purged with nitrogen. Thereafter, vacuum was applied to remove excess aminopropyltrimethoxysilane to obtain one-terminal aminopolydimethylsiloxane. To 100 g of the obtained reaction product, 0.77 g of 2-isocyanatoethyl methacrylate was added and stirred for 1 hour at 50 ° C. in a nitrogen atmosphere to obtain polydimethylsiloxane having a methacryloyl group at the end. To this, 0.5 g of 1-hydroxycyclohexyl phenyl ketone and 10 g of starch-based water-absorbing swellable powder (Sunwet, Sanyo Chemical Co., Ltd.) were added as a photoinitiator to obtain an ultraviolet curable sealing material composition.

Example 2 (Composition 2)
1 g of cumene hydroperoxide as an organic peroxide, 10 g of starch-based water-absorbing swellable powder (Sunwet manufactured by Sanyo Kasei), polyethylene resin powder (melting point 80) (30 ° C., average particle size 20 μm) was added in an amount of 30 parts by weight to obtain a thermosetting sealant composition.

Example 3 (Composition 3)
70 parts by weight of an organopolysiloxane having a vinyl group bonded directly to a silicon atom at the molecular end with a viscosity of 15 Pa · s at 25 ° C., 30 parts by weight of a trimethylsiloxy-terminated methylhydrogensiloxane-dimethylsiloxane copolymer having a molecular weight of about 2000, plastic 60 parts by weight of a polydimethylsiloxane having a trimethyl group at the end, 0.1 parts by weight of a platinum divinyltetramethyldisiloxane complex, and 10 parts by weight of an acrylic acid polymer-based water-swellable powder (Aquaric CA, manufactured by Nippon Shokubai), 20 Part by weight and 3 parts by weight of an acetylenic alcohol as a storage stabilizer were mixed to obtain a thermosetting sealant composition.

Example 4 (Composition 4)
In addition, 30 parts by weight of polypropylene resin powder (melting point: 140 ° C., average particle size: 20 μm) was added to the sealing agent obtained in Example 3 to obtain a thermosetting sealing agent composition.

Example 5 (Composition 5)
16.3 g of aminopropyldimethoxysilane was added to 2000 g of terminal silanol polydimethylsiloxane having a molecular weight of about 10,000, and the mixture was stirred and reacted at 100 ° C. for 2 hours while being purged with nitrogen. Thereafter, vacuum was applied to remove excess aminopropyltrimethoxysilane to obtain one-terminal aminopolydimethylsiloxane. To 100 g of the resulting reaction product, 2.1 g of 3-isocyanatopropyltriethoxysilane was added and stirred and reacted at 50 ° C. for 1 hour while substituting with nitrogen to obtain an organopolysiloxane having a trimethoxysilane terminal. To this, 0.5 g of dibutyltin octate and 10 g of starch-based water-absorbing swellable powder (Sunwet, Sanyo Chemical Co., Ltd.) were added as a moisture curing catalyst to obtain a moisture curable sealing material composition.

Comparative Example 1 (composition ratio 1)
An ultraviolet curable sealing material composition was obtained in the same procedure as in Example 1 except that starch-based water-absorbing swellable powder (Sunwet, Sanyo Chemical Co., Ltd.) was not added.

Comparative Example 2 (composition ratio 2)
A heat-curable sealant composition was obtained in the same procedure as in Example 4 except that the acrylic acid polymer-based water-swellable powder (AQUALIC CA, manufactured by Nippon Shokubai Co., Ltd.) was not added.

  The following tests were conducted using the compositions 1 to 5, the ratio 1 and the ratio 2 (hereinafter collectively referred to as various sealing material compositions) obtained as described above.

Penetration degree Various sealing material compositions were put in a container, and reactive groups were crosslinked by a suitable curing method to obtain a gel-like cured product. Curing conditions were as follows: heat curing at 120 ° C. for 60 minutes, and ultraviolet irradiation with a high pressure mercury lamp at 3000 mJ / cm 2 (365 nm). The obtained cured product was measured for penetration by a 1/4 cone defined by JIS K2220. However, the penetration of the composition 5 was not measured because it was difficult to obtain a thick cured product because it was moisture curable.

Tensile strength (breaking strength)
Various sealing material compositions were cured into a sheet shape, made into a dumbbell shape, and the tensile strength defined by JIS K6251 was measured.

Workability Various sealing material compositions were applied to the threaded portion of a 25A steel union screw joint and cured under the above conditions. The steel pipe was connected using the union screw joint. In that case, it was marked with ○ when not using a tool, and × when not using a tool. Further, the threaded joint was removed after completing the following sealing performance test. At that time, it was marked with ○ when it could be removed without using a tool, and x when it could not be removed.

Sealing performance Various sealing material compositions were applied to the threaded portion of a 25A union screw joint and cured under the above conditions. A steel pipe was connected using the union screw joint, and water was allowed to flow through the pipe line at 0.2 MPa water pressure. Similarly, the water pressure was 0.8 MPa. The presence or absence of water leakage from the threaded joint and the time of water leakage were measured. These results are shown in Table 1.

Comparative Example 3
The sealing material composition obtained in Example 2 was cured in a string shape to obtain a string-like gel-like cured product. This was uniformly wound around the above-described screw joint to cover the screw portion. This was tested in the same manner as the above workability and sealing performance.

Comparative Example 4
The sealing material composition obtained in Example 4 was cured in a string shape, and a string-like gel-like cured product was obtained. This was uniformly wound around the above-described screw joint to cover the screw portion. This was tested in the same manner as the above workability and sealing performance.

Comparative Example 5
Using a moisture-curing silicone resin, which is a rubber-like cured product, in the same manner as the above workability test, tightening was possible by hand, but after leaving it for 60 minutes, it was removed by hand. It could not be removed.

The sealing material composition used by pre-coating the screw portion of the present invention is applied to the screw portion to be crosslinked, whereby a pre-coated sealing material pre-coated on the screw portion is obtained. The precoat type sealing material of the present invention can be used for threaded joints such as nipples, sockets, elbows, and cloths.

Claims (4)

(A) Reactive liquid resin that has a crosslinkable reactive group in the molecule and becomes a gel-like cured product by crosslinking (B) A catalyst and / or a curing agent (C) that absorbs water swellable components A sealing material composition that is used by pre-coating on a screw part characterized by the above. The sealing material composition used by pre-coating the screw part according to claim 1, wherein (D) an organic resin powder is further added to the (A) to (C). (A) A reactive liquid resin having a reactive group in the molecule and forming a gel-like cured product by crosslinking (B) A catalyst or a curing agent for crosslinking the component (A) or a curing agent (C) a sealing material composition comprising a water-absorbing swellable component A pre-coated sealing material, wherein the screw portion is pre-coated. The precoat-type sealing material according to claim 3, wherein (D) an organic resin powder is further added to the (A) to (C).