JPH10152672A - Method for forming gasket - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for forming a gasket which has no risk of contact surface leakage occurring as a result of the flatting of the gasket layer upon long-term use and can satisfactorily follow the movement of the surface of a flange. SOLUTION: This invention provides a sealing agent composition comprising a reactive prepolymer having at least two (meth)acryloyl groups in the molecule and having a weight-average molecular weight of 10,000-200,000, a (meth)acrylic ester monomer having a glass transition temperature equal to or lower than room temperature, an aerobic curing catalyst and a photocuring catalyst and a method for forming a gasket, comprising applying the above composition to either sealed surface to form a pattern of beads having a thickness of 0.5-20mm, irradiating the coated surface with light in such a suitable dosage that the surface of the applied composition can remain uncured, and its inside can be cured into a rubbery substance to form a gasket having a two-layer structure composed of the surface uncured layer and the inside rubbery elastic layer and pressing the sealed surface against the gasket to anaerobically cure the uncured sealing material.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sealing method for sealing a flange surface using a liquid sealant in an assembling process of automobile parts, electric parts, various mechanical parts and the like. For more information, please refer to the sealing technology, which applies the liquid sealant to the flange surface using an automatic coating machine etc. on the assembly line of the oil pan, transmission case, differential case, etc. of the automobile engine, and assembles it as it is. An object of the present invention is to improve the curing speed, followability to the movement of the flange surface, decomposability, and the like, and to simplify the process management during the line downtime.

[0002]

2. Description of the Related Art Conventionally, as a method of joining and sealing automobile parts, electric parts, and various machine parts on an assembly line, there is a method in which a molded gasket made of rubber, cork, or paper is interposed between sealing surfaces and pressed. A method has been adopted in which a liquid sealing agent is interposed between sealing surfaces to seal. Among them, the method using a molded gasket has problems such as material loss due to punching and high molding processing cost of the gasket,
If the gasket is used for a long time, there is a problem that a set is generated, a bolt tightening torque is reduced, and a leak is generated from a contact surface.

[0003] In particular, in an assembly line for an oil pan, a transmission case, a differential case, a water pump, and the like of an automobile engine, a FIPG (Formed-Foiled) is used in which a liquid sealant is applied to the flange surface by an automatic coating machine or the like and assembled as it is to seal. In-
(Place-Gaskets) sealing technology has become mainstream due to its high productivity, low cost, and reliability of sealing performance. As a sealing material for FIPG, a room-temperature-curable silicone material (silicone RTV), which cures by reacting with moisture in the atmosphere, and an anaerobic liquid sealing agent mainly containing urethane (meth) acrylate are mainly used.

However, silicone RTV has the following problems.

[0005] A firing test is performed on the assembly line of an automobile engine immediately after the engine is assembled. At this point, since the silicone RTV in the flange is not cured, the uncured liquid on the sealing surface with a large clearance is not cured. The so-called low initial pressure resistance, in which the sealant is swept away by the internal pressure to cause leakage, has been a problem. This is a serious problem particularly in a flange structure in which the distance between the fastening bolts is wide, an oil pan having a small thickness of a pressed steel plate, and an oil pan having an arch-like flange shape.

Since silicone RTV reacts with atmospheric moisture and cures only gradually from the surface, it takes a very long time to completely cure the inside of the flange.
When the vehicle travels in an uncured state, leakage may sometimes occur due to movement occurring on the flange surface.

[0007] The flange material of the oil pan is generally made of different materials such as iron and aluminum in many cases. Therefore, the thermal expansion coefficient varies depending on the temperature change of the engine part. Shift occurs,
It is required that the sealing agent layer has high followability. This problem is particularly significant for larger engines. The lateral displacement of the flange surface can be alleviated by increasing the thickness of the gasket, but the initial pressure resistance when the thickness of the gasket is increased is deteriorated. Therefore, the sealing agent itself is required to have a high elongation so as to cope with a lateral displacement.

[0008] SAE, 1986, FEBRUARY24
According to −28, P75-80, a temperature difference of 66 ° C. occurs between the rocker cover and the engine block when starting the engine in the rocker cover having a length of 25.4 cm. It has been described that a deviation of 0.23 mm has occurred. Furthermore, if the engine block is made of aluminum, a shift of 0.46 mm will occur, which is twice as large. That is, at this point, if the gasket layer is hardened firmly and the design is not designed to follow this amount of displacement, the gasket layer will be broken, and interlayer leakage will occur. At present, an oil pan used in a mass-produced vehicle is about 60 cm in a length direction, so that a countermeasure against the lateral displacement is a more serious problem. Similarly, the performance of the gasket agent layer improves as the thickness of the gasket agent layer increases, as well as the decomposability and soundproofing of the flange surface.

When the vibration of the engine block is transmitted to the oil pan, the oil pan reverberates and generates a loud noise. Therefore, a so-called metal touch structure sealing method in which the clearance on the flange surface is reduced is inappropriate from the viewpoint of soundproofing.

When disassembling when required for maintenance or the like, the use of a metal touch seal structure makes it difficult to open the flange surface at the initial stage of disassembly, even if the adhesive strength of the sealant itself is low. In extreme cases, the flange may be deformed.

When the silicone RTV is exposed to the atmosphere, it reacts with the moisture in the air and quickly cures from the surface. Therefore, the tip of the nozzle is hardened during the downtime of the production line, or the surface of the coated bead is hardened. In some cases, poor adhesion may occur due to the skinning, so that the process management of the FIPG sealing operation is troublesome.

In order to solve the above-mentioned various problems, several solutions have hitherto been made. For example, silicone R
FIP to address the problem of initial withstand voltage in TV
The method of making the viscosity of the G sealant extremely high is adopted. However, when manufacturing the sealant, it is difficult to manufacture the sealant, or when applying the sealant to the flange surface,
There is a problem that it is difficult to apply. Further, it is a reality that the initial pressure resistance is not sufficiently satisfied even if a liquid sealant having a viscosity increased to such an extent that there is no problem in production or application work.

Next, in order to improve the internal curability, Japanese Patent Application Laid-Open
JP-A-52955 discloses a deoxime type silicone RTV.
A rapid curing silicone RTV using an oxime silane containing a vinyl group or a phenyl group as a curing agent has been proposed, but it cannot be said to provide sufficient internal curability. Japanese Patent Laid-Open Publication No. Hei 3-50287 proposes a method of applying a two-liquid silicone sealant while mixing two liquids on a part assembly line, but requires an expensive two-liquid mixing apparatus, and the line is stopped. There is a drawback that the process management becomes very complicated because the mixing nozzle part is hardened during the time.

On the other hand, in the case of an anaerobic liquid sealant containing a urethane (meth) acrylate compound as a main component, the hardening does not proceed unless the sealant is completely sandwiched between the flange surfaces and cut off from oxygen in the air. .2mm
There is a problem that the resin is hardened only on the flange surface of not more than 0.05 mm (actually, 0.05 mm or less). For this reason, its use has been limited only to a flat flange surface obtained by finely cutting a casting surface.

Further, the anaerobic liquid sealant needs to come into contact with the metal surface in order to cure, and there is a disadvantage that the anaerobic sealant does not cure on the painted flange surface. Therefore, when used in places where these clearances are large or on painted surfaces, a curing agent containing a reducing agent that promotes the decomposition of organic peroxide and generates radicals on the other flange surface that has not been coated with a sealant in advance A technique of improving curability by applying an accelerating primer is also used.

However, this method also has a problem that when the clearance of the flange is 0.5 mm or more, the catalytic effect of the primer does not penetrate into the inside of the sealant, so that the inside is not completely cured. There is a problem that it increases, and that a highly flammable solvent-based primer must be used in the assembly line.

The inventor of the present invention first irradiates a photocurable and moisture-curable composition having a dual curing function with light, as disclosed in JP-A-6-158024, so that the surface portion is reduced. In the state where it is not cured due to oxygen inhibition, only the inside of the sealing agent coating bead is cured into a rubber shape and then assembled, expressing high initial sealing performance, the surface part is gradually cured by moisture curing, and both flange surfaces A method was proposed to completely prevent leakage of the contact surface by finally bonding to the surface.However, since the surface portion is in a form that is hardened by contact with the moisture in the air, it takes a long time to completely harden the inside of the flange. There is a disadvantage that it takes time, which is not enough for practical use.

On the other hand, Japanese Patent Publication No. 3-32593 discloses a method for solving the problem that a flange having a large clearance, which is a drawback of an anaerobic seal, does not cure (meta).
An anaerobic sealant containing an acrylate ester monomer as a main component is blended with an ultraviolet curing agent, and the sealant is applied on the flange surface and then irradiated with ultraviolet light to partially cure the sealant, thereby forming a gel. A sealing method has been proposed in which, after forming an adhesive surface, the other flange is assembled and anaerobically cured.

However, this method has several problems as described below. First, in the present invention, since a (meth) acrylate ester monomer having a relatively small molecular weight is used, sufficient elongation and good resilience cannot be obtained, and even if the thickness of the sealant layer can be increased, sufficient follow-up can be achieved. I can not expect sex. In a transmission case where the movement of the flange surface is not so large, such an elongation rate is 10%.
Although a sealant of 0% or less can be used satisfactorily, it cannot be used on a non-rigid flange surface such as an oil pan as a sheet metal part unless the sealant has a large elongation of at least 100% or more.

[0020]

In order to solve the above problems, in FIPG sealing technology, a high initial sealing property is developed immediately after assembling. We have invented a method of forming a sealant which can cope with vibration and lateral displacement, does not cause contact surface leakage, and has excellent followability, soundproofing, and decomposability. That is, the present invention relates to (A) a reactive prepolymer having at least two (meth) acryloyl groups in one molecule and having a weight average molecular weight of 10,000 to 200,000; (Meth) acrylate monomers. (C) Anaerobic curing catalyst (D) Photocuring catalyst A liquid sealing composition comprising the above components (A), (B), (C) and (D) is applied on one of the surfaces to be sealed in a range of 0.5 mm to
The liquid sealant composition is applied in a bead shape with an application thickness of 20 mm, and the surface of the liquid sealant composition is left uncured while the inside is irradiated with an appropriate amount of light to cure the rubber-like material. A method for forming a gasket, comprising: forming a gasket having a two-layer structure of an elastic inner layer; and pressing an uncured sealant anaerobically by pressing a surface to be sealed facing the gasket. It is in.

Further, as a preferred embodiment of the present invention, the component (A) is (A-1) an acryl having at least two (meth) acryloyl groups in one molecule and having a weight average molecular weight of 10,000 to 200,000. Rubber or (A-2)
An ethylene-acryl rubber having at least two (meth) acryloyl groups in one molecule and having a weight average molecular weight of 10,000 to 200,000 is more preferable.

According to the method of the present invention, the rubber of the gasket material after curing has a high elongation rate and is excellent in the compression restoring property, so that an excellent initial sealing property and a high ability to follow the movement on the flange surface can be obtained.

Further, by using an acylphosphine oxide-based visible light curing catalyst as the photocuring catalyst of the component (D), the initial cost and running cost of xenon lamps, halogen lamps and near infrared lamps are reduced, and the working environment is reduced. The production cost is low because the visible light lamp light source which has little effect on the human body in the room can be used.
It is possible to realize a production system with high security of the IPG sealing operation. Also, if a visible light curing catalyst is used, even if the amount of the photoinitiator added is increased or excessive light irradiation is performed, only the surface of the sealant applied bead is uncured, and only the inside can be cured well. Therefore, an effect suitable for the gasket forming method of the present invention, which facilitates the process control of the FIPG sealing operation, can be obtained at the same time. In addition, the anaerobic and photocurable sealant composition of the present invention is a one-part composition, and the curing does not progress even if it is exposed to the air during the downtime of the line operation, so that the process control is simple.

Hereinafter, the sealing method will be described with reference to the drawings.
A sealing agent bead is applied on the flange surface to a thickness of 0.5 mm or more, and irradiated with light energy. Fig. 1
The surface of the bead is uncured and only the inside is cured like a rubber. In FIG. 1, 1 is an uncured surface layer, 2 is a rubber-like cured layer, and 3 is a flange. If the thickness of the sealant bead is 0.5 mm or less, particularly 0.2 mm or less, the whole is not cured due to the effect of oxygen inhibition, and is cured by separating the uncured layer and the cured layer as shown in FIG. It is difficult to make it happen. It is preferably applied to a thickness of 0.5 to 20 mm, and the thickness of the uncured layer is generally 0.1 mm or less. 20m
Above m, it becomes difficult to completely cure the bottom of the coating bead by light irradiation, and it is not very practical to harden to a thickness greater than this in view of the followability of the gasket and the soundproofing effect. .

Next, by joining the other flange surface to the sealant bead separated and hardened into two layers and compressing the sealant bead, the initial pressure resistance is immediately exhibited by the repulsive effect of the fixed gasket. This is shown in FIG. Further, the uncured surface sealing agent layer that has contacted the flange surface is blocked from the effect of oxygen inhibition and is in contact with the metal surface, so that it hardens and hardens at room temperature in a short time by anaerobic hardening. As a result, a gasket layer of any thickness is formed to some extent, and since this gasket is firmly adhered to both sides of the flange, there is no fear of leakage at the contact surface, and excellent followability to the movement of the flange surface, long-term use In such a case, the problem of settling of the gasket layer does not matter.

Here, the follow-up performance of the gasket is determined by the elongation of the gasket material and the thickness of the gasket material layer. That is, as the elongation of the gasket material increases and the thickness of the gasket agent layer increases, the performance of following the movement increases.

The method of applying the liquid sealant composition to the flange surface is performed by automatically applying the liquid coating composition to the flange surface at an arbitrary coating thickness from the tip of the application nozzle by an automatic application robot most widely used in the art. Is preferred. At this time, in order to apply the application beat to an arbitrary thickness, the liquid sealant composition has an appropriate thixotropic property,
It is necessary that even if it is applied to a certain thickness, it does not flow. Also, the thickness to be applied is the size of the inner diameter of the application nozzle,
It can be arbitrarily adjusted by the discharge speed of the sealing material and the application speed.

Of course, other commonly used methods such as a stencil coating method and a screen printing method can also be used. However, the stencil method has a problem that the degree of freedom of the shape is small and the productivity is low. Not very suitable. Next, in the screen printing method, the coating thickness is 0.3 mm
There is a problem that the coating is difficult as described above, and it is not suitable for the coating method of the present invention. In addition, it is of course possible to produce the product by applying it manually with a caulking gun or the like, but it is limited to the use places where the number of products is not so large.

The component (A) used in the present invention has a weight average molecular weight of 10,000 to 200,000 and two or more (meth) components per molecule.
As the reactive prepolymer having an elastomer skeleton having an acryloyl group, the prepolymer skeleton has polyether, polyester, polybutadiene, polycarbonate polyisoprene, an acrylic copolymer, an ethylene-acryl copolymer, and the like, and has a terminal or side thereof. Those having a (meth) acryloyl group introduced into the chain can be used.

Among these, oil resistance, low-temperature embrittlement,
A prepolymer having a polyether skeleton in the prepolymer skeleton and introducing (meth) acryloyl groups at both ends via urethane bonds is presently the most practical because of its rubber elasticity as a gasket. As a specific example, a urethane (meth) acrylate prepolymer as disclosed in JP-A-64-112 can be used.

Hereinafter, a specific method for producing a urethane (meth) acrylate prepolymer having a weight average molecular weight of 10,000 or more will be described. It is obtained by mixing and reacting a polyether polyol or the like and an organic diisocyanate in a molar ratio of 1: 1 to 1: 2 in a diluting solvent or in a (meth) acrylate monomer having no active hydrogen group. Obtained by reaction with a (meth) acrylate monomer having sufficient active hydrogen groups to react with all remaining isocyanate groups of the urethane prepolymer.

The component (A-1) used in the present invention has a weight average molecular weight of 10,000 to 200,000 and has at least two or more (meth) acryloyl groups in the molecule.
The acrylic rubber of the present invention can be synthesized in several ways. The following method can be used as a specific example.

First, as a first step, an acrylic rubber having a first reactive group in a side chain is synthesized. However, the acrylic rubber must have at least two or more first reactive groups.

100 parts by weight of a polymerizable (meth) acrylate monomer having a glass transition point of room temperature or lower, a hydroxyl group,
Glycidyl group, 1 to 20 parts by weight of a radical polymerizable monomer having a first reactive group selected from a carboxyl group, and an appropriate amount of a polymerization catalyst are added to a side chain by polymerization in a solution or by an emulsion polymerization method. An acrylic rubber polymer having a first reactive group can be obtained.
The weight average molecular weight of the acrylic rubber polymer having the first reactive group in the side chain is in the range of 10,000 to 200,000. If it is less than 10,000, sufficient elasticity and elongation as a sealant are not exhibited. On the other hand, when it is more than 200,000, when it is dissolved in an acrylic monomer to be liquefied, the operation is difficult, or the amount of the acrylic monomer added is too large, and sufficient heat resistance and rubber strength are not exhibited.

Further, if necessary, acrylic acid, methacrylic acid, acrylonitrile,
A polar monomer such as cyanoethyl acrylate is added in an amount of 0 to 100 parts by weight of a (meth) acrylate monomer;
The copolymerization can be carried out in the range of ２０20 parts by weight. Furthermore, if necessary, when imparting cold resistance, an alkoxyalkyl acrylate having an alkoxy group having 1 to 8 carbon atoms, such as methoxymethyl acrylate, methoxyethyl acrylate, ethoxyethyl acrylate, or butoxyethyl acrylate, is added as necessary. It can also be copolymerized.

Here, as a main component of the acrylic rubber, a polymerizable acrylate monomer having a glass transition point of room temperature or lower or a methacrylate monomer such as ethyl (meth) acrylate or n-propyl ( (Meth) acrylate, isopropyl (meth) acrylate, isobutyl (meth) acrylate, t-butyl (meth) acrylate, n-hexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, n-octyl (meth) acrylate, isooctyl ( Meth) acrylate, isononyl (meth) acrylate, n-decyl (meth) acrylate, isodecyl (meth) acrylate,
n-lauryl (meth) acrylate, 2-methoxyethyl (meth) acrylate, 2-ethoxyethyl (meth)
Acrylate, 2-phenoxyethyl (meth) acrylate, stearyl (meth) acrylate, tridecyl (meth) acrylate, 3-methoxypropyl (meth)
Acrylate and 3,3-methoxymethylpropyl (meth) acrylate. Economics in this,
Ethyl (meth) acrylate and t-butyl (meth) acrylate are particularly preferred from the viewpoint of oil resistance.

Examples of radically polymerizable monomers having a first reactive group in which the first reactive group is a hydroxyl group include 2-hydroxyethyl (meth) acrylate, hydroxypropyl (meth) acrylate, and butanediol mono (meth) acrylate. Examples thereof include acrylate, ethylene glycol (meth) acrylate, and propylene glycol (meth) acrylate, and 2-hydroxyethyl (meth) acrylate is most preferable from the viewpoint of economy.

Examples of radically polymerizable monomers having a first reactive group in which the first reactive group is a glycidyl group include glycidyl (meth) acrylate, EO-modified phthalic acrylate (manufactured by Osaka Organic Synthesis Co .;
Biscoat 2308), EO-modified phthalic methacrylate (manufactured by Kyoeisha Yushi Co., Ltd .; light ester HOmlp),
EO-modified succinic acid (meth) acrylate and the like,
Glycidyl (meth) acrylate is most preferred in terms of economy.

Examples of the radically polymerizable monomer having a first reactive group in which the first reactive group is a carboxyl group include acrylic acid and methacryloxyethyl phthalate. Most preferred.

In the second step, the acrylic rubber having the first reactive group in the side chain synthesized above, the second reactive group and the compound having a (meth) acryloyl group are bonded by a condensation reaction, an addition reaction, or the like. Let it. However, it is necessary to select such that the first reactive group and the second reactive group are reacted by a condensation reaction, an addition reaction, or the like.

For example, when the first reactive group is a hydroxyl group, the second reactive group is preferably an isocyanate group, and when the first reactive group is a glycidyl group, the second reactive group is an isocyanate group and a carboxyl group. Preferably, when the first reactive group is a carboxyl group, an isocyanate or glycidyl group is preferred. These examples are examples in which the reaction is relatively easy to occur, and other examples can be selected.

As described above, the first reactive group and the second reactive group are selected, and the acrylic rubber having the first reactive group is reacted with the second reactive group and the compound having a (meth) acryloyl group. Thereby, a (meth) acryloyl group can be introduced into the side chain of the acrylic rubber, and an acrylic rubber having at least two or more (meth) acryloyl groups in one molecule can be synthesized.

Examples of the compound having a second reactive group and a (meth) acryloyl group include 2-isocyanatoethyl methacrylate, 2-isocyanatoethyl acrylate and 4-isocyanate ethyl acrylate when the second reactive group is an isocyanate group.
-Isocyanate butyl methacrylate, 4-isocyanate butyl acrylate, methacryloyl isocyanate, acryloyl isocyanate and the like.

When the second reactive group is a carboxyl group, acrylic acid, methacrylic acid, 2-methacryloyloxyethyl succinic acid, 2-methacryloyloxyethyl phthalic acid, 2-acryloyloxypropyl hydrogen phthalate, 2-acryloyloxy Examples thereof include propyl hydrogen phthalate, 2-acryloyloxypropyl hexahydrohydrogen phthalate, and 2-acryloyloxypropyl tetrahydrohydrogen phthalate.

When the second reactive group is a glycidyl group, examples thereof include glycidyl methacrylate and glycidyl acrylate.

As a reaction catalyst for reacting the first reactive group and the second reactive group of the acrylic rubber, a tertiary amine or an organometallic compound when a hydroxyl group or a carboxyl group is reacted with an isocyanate group is used. And an organic tin compound such as dibutyltin dilaurate is particularly preferable. Examples of a reaction catalyst for reacting a carboxyl group with a glycidyl group include triethylenediamine, triethylamine, benzylamine, triethanolamine, triisoamylamine and tributylamine.
Quaternary ammonium salts such as quaternary amines, benzyltrimethylammonium chloride, tetraethylammonium chloride, tetrabutylammonium chloride, and tetrabutylammonium bromide; borate esters such as triethyl borate; organic metal salts such as tin octylate; and Cr acetyl acetate Can be used.

The addition amount of these reaction catalysts is 0.1 to 10
It is preferable to use it by adding in the range of weight%. The conditions for the reaction are 50 to 50 with stirring in a stirring vessel.
The reaction is completed under a temperature condition of 200 ° C. for about 1 to 5 hours. Usually, it may be about 1 to 3 hours under a temperature condition of 80 ° C to 150 ° C. When reacting an isocyanate group with a carboxyl group, it is better to carry out the reaction under a nitrogen stream in order to suppress the reaction with moisture in the air.

The third step is to evaporate the solvent when the acrylic rubber is synthesized by the solution polymerization method, and to volatilize the water when the acrylic rubber is synthesized by the emulsion polymerization method (A-1).
An acrylic rubber having two or more (meth) acryloyl groups in one molecule of the component can be obtained.

If the boiling point of the polymerizable (meth) acrylate monomer having a glass transition point of the component (B) of room temperature or lower is higher than that of a solvent in which the boiling point is volatilized or water, the (meth) After adding the acrylate monomer, the solvent or water may be volatilized and removed.

The component (A-2) contains at least 2 in one molecule.
An ethylene-acryl rubber having at least one (meth) acryloyl group and having a weight average molecular weight of 10,000 to 200,000. Here, the ethylene-acrylic rubber is obtained by copolymerizing acrylic acid ester and ethylene as a basic main chain. Therefore, the component (A-2) is obtained by adding ethylene to the first production step of the component (A-1) and polymerizing the same. Specifically, it can be obtained by copolymerizing ethylene, a (meth) acrylate monomer and a radical polymerizable monomer having a first reactive group in the same manner as in (A-1).

The weight average molecular weight of the ethylene-acryl rubber polymer having the first reactive group in the side chain is preferably in the range of 10,000 to 200,000. If it is less than 10,000, sufficient elasticity and elongation as a sealant are not exhibited. On the other hand, when it is more than 200,000, when it is dissolved in an acrylic monomer to be liquefied, the operation is difficult, or the amount of the acrylic monomer added is too large, and sufficient heat resistance and rubber strength are not exhibited.

Further, if necessary, acrylic acid, methacrylic acid, acrylonitrile,
A polar monomer such as cyanoethyl acrylate is added in an amount of 0 to 100 parts by weight of a (meth) acrylate monomer;
The copolymerization can be carried out in the range of ２０20 parts by weight. Furthermore, if necessary, when imparting cold resistance, an alkoxyalkyl acrylate having an alkoxy group having 1 to 8 carbon atoms, such as methoxymethyl acrylate, methoxyethyl acrylate, ethoxyethyl acrylate, or butoxyethyl acrylate, is added as necessary. It can also be copolymerized.

At least one molecule of the component (A-2)
The ethylene-acryl rubber having a weight average molecular weight of 10,000 to 200,000 having at least one (meth) acryloyl group is the component (A-1) in which the first reactive group in the side chain of the ethylene-acryl rubber synthesized above is used. And a compound having a (meth) acryloyl group.

Ethylene-acrylic rubber having a first reactive group and having a weight average molecular weight of 10,000 to 200,000 is commercially produced. For example, ethylene-acrylic rubber in which the first reactive group is a carboxyl group is "V" manufactured by DuPont.
AMAC], an ethylene-acryl rubber in which the first reactive group is a glycidyl group is "Esprene EM" manufactured by Sumitomo Chemical Co., Ltd.
A "and the like.

A polymerizable acrylic ester monomer having a glass transition point of the component (B) used at room temperature or lower,
Alternatively, methacrylic acid ester monomers include ethyl (meth) acrylate, n-propyl (meth) acrylate, isopropyl (meth) acrylate, isobutyl (meth) acrylate, t-butyl (meth) acrylate, and n-hexyl (meth) Acrylate, 2-ethylhexyl (meth) acrylate, n-octyl (meth) acrylate, isooctyl (meth) acrylate, isononyl (meth) acrylate, n-decyl (meth) acrylate, isodecyl (meth) acrylate, n-lauryl (meth) Acrylate, 2-methoxyethyl (meth) acrylate, 2-ethoxyethyl (meth) acrylate, 2-phenoxyethyl (meth) acrylate,
Stearyl (meth) acrylate, tridecyl (meth)
Acrylate, 3-methoxypropyl (meth) acrylate, 3,3-methoxymethylpropyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate,
And hydroxypropyl (meth) acrylate. These polymerizable acrylate monomers having a glass transition point of room temperature or lower may be used singly or as a mixture of any two of them.

The amount of the component (B) added is (A)
It is necessary to dissolve the ingredients and add an amount that can be liquefied,
The blending amount varies depending on the compatibility with the component (A),
If the compounding amount is too large, there is a problem that the heat resistance and rubber physical properties of the liquid sealant after curing are deteriorated. Therefore, the addition amount of the component (B) is 5 to 200 parts by weight based on 100 parts by weight of the component (A).
It is preferable to add in the range of parts by weight.

It is preferable to use an organic peroxide and an anaerobic accelerator as the anaerobic curing catalyst of the component (C). Cumene hydroperoxide as specific examples of the organic peroxide,
Other than hydroperoxides such as t-butyl hydroperoxide and diisopropylbenzene hydroperoxide, there are diacyl peroxides, dialkyl peroxides, ketone peroxides, peroxyesters and the like, and especially cumene hydroperoxide. It is preferable in terms of stability and curing speed.

Examples of the curing accelerator include organic sulfonimides, amines, and organic metal salts. Of these, o-benzoic sulfonimides are preferable as the organic sulfonimides, and diethylamine, triethylamine, and amines as the amines. N, N-dimethylparatoluidine, 1,2,3,4-tetrahydroquinone and the like are preferable, and examples of the organic metal salt include copper chloride and copper octylate.

As the photocuring catalyst of the component (D), acetophenone, which is generally known as an ultraviolet initiator,
Propiophenone, benzophenone, xanthol, fluorein, benzaldehyde, anthraquinone, triphenylamine, carbazole, 3-methylacetophenone, 4-methylacetophenone, 3-pentylacetophenone, 4-methoxyacetophenone, 3-bromoacetophenone, p-diacetyl Benzene, 3-methoxybenzophenone, 4-allylacetophenone, 4-chloro-4-benzylbenzophenone, 3-chloroxanthone, 3,9-dichloroxanthone, 3-chloro8-
Nonyl xanthone, benzoyl, benzoin methyl ether, bis (4-dimethylaminophenyl) ketone,
Benzyl methoxy ketal, 2-chlorothioxatone, 2,4,6-trimethylbenzoyldiphenylphosphine oxide and the like can be used.

As the component (D), in particular, the gasket forming work environment is improved, the cost of the apparatus is further reduced, and furthermore, only the inside of the gasket-coated bead is completely cured while the surface intended for the present invention is uncured. Therefore, it is more desirable to use a visible light curing catalyst. Specific examples of the visible light curing catalyst are shown below. Carbonyl catalysts such as benzyl, camphorquinone, 3-ketocoumarin, anthraquinone, α-naphthyl, acenaphthene, p, p′-dimethoxybenzyl, and p, p′-dichlorobenzyl; Thioxanthone-based catalysts such as 2-chlorothioxanthone, 2-methylthioxanthone, 2,4-diethylthioxanthone and 2,4-dimethylthioxanthone. 2,4,6-trimethylbenzoyldiphenylphosphine oxide, bis (2,6-dimethoxybenzoyl) -2,4,4-trimethyl-pentylphosphine oxide, bis (2
Acylphosphine oxides such as 6-dichloro-benzoyl) -4′-n-propylphenylphosphine oxide and bis (2,6-dimethylbenzoyl) diphenylphosphine oxide.

These initiators may be used alone,
Two or more types may be used in combination. The amount of addition is from 0.05 to 10 parts by weight based on 100 parts by weight of the base resin obtained by mixing the components (A) and (B). In particular, when it is intended to completely cure only the interior while only the surface intended for the present invention is uncured, the amount of the photoinitiator to be used is preferably in the range of 0.1 to 1 part by weight.

However, benzoin butyl ether, 2,
Benzoin-based initiators such as 2'-di-methoxy-2-phenylacetophenone have good surface curability and it is practically difficult to leave an uncured layer.

In a system in which camphorquinone and a tertiary amine are combined, it is sufficiently possible to cure only the surface layer in an uncured state, but if the light irradiation time is not longer than 300 seconds, the inside will not be sufficiently cured. Has problems in line production.

On the other hand, acylphosphine oxides such as 2,4,6-trimethylbenzoyldiphenylphosphine oxide and bis (2,6-dimethoxybenzoyl) -2,4,4-trimethyl-pentylphosphine oxide are The internal curing speed is high, and only the surface layer can be cured sufficiently in an uncured state.

In particular, a mixture of bis (2,6-dimethoxybenzoyl) -2,4,4-trimethyl-pentylphosphine oxide and 2-hydroxy-2-methyl-1-phenylpropan-1-one is preferably a xenon lamp. Not only visible light lamps such as halogen lamps and incandescent lamps, but also ultraviolet lamps such as high-pressure mercury lamps, the surface layer is sufficiently uncured and the interior is cured in a short time.

In the present invention, a tertiary amine can be used, if necessary, to enhance photocurability. Preferred examples of the tertiary amine used in the present invention include triethylamine, triethylamine, tributylamine, N,
N'-diethanolamine, N, N'-dimethyl-P-
Toluidine, N, N′-dimethyl-aniline, N-methyl-diethanolamine, N-methyl-dimethanolamine, N, N ′-(dimethylamino) ethyl-methacrylate, N, N′-dimethylamino-acetophenone,
N, N'-dimethylaminobenzophenone, N, N'-
And diethylamino-benzophenone.

The preferred addition amount of the tertiary amine in the present invention may be a catalyst stoichiometric amount sufficient to give photocurability, and differs depending on the radical polymerizable compound used.
0.1 to 100 parts by weight of the radical polymerizable compound
1.0 part by weight, preferably 0.3 to 0.6 part by weight. If the amount is less than 0.1 part by weight, sufficient sensitivity cannot be obtained, which affects the curing. On the other hand, if the amount is more than 1.0 part by weight, the curing of only the surface proceeds, which strongly affects the curability in the deep part.

In addition, various fillers such as fumed silica and fused silica, plasticizers, and the like may be added to the liquid sealant composition for viscosity adjustment such as imparting thixotropic properties, if necessary. Adhesion-imparting agents such as silane compounds and phosphate esters, isobornyl (meth) acrylate, 2-
Various known acrylate monomers such as hydroxyethyl (meth) acrylate and 2-hydroxypropyl (meth) acrylate, or methacrylate monomers may be blended.

[0069]

【Example】

(Base polymer) A urethane methacrylate polymer (P-1) was synthesized by the following method. 0.19 mol of a diol having an average molecular weight of 2,800 represented by the structural formula of Formula 1 and 0.2 mol of trimethylhexamethylene diisocyanate were mixed in the presence of a polymerization inhibitor butylhydroxytoluene (0.4% by weight). , Based on the weight of this mixture.
01 wt% of dibutyltin dilaurate was mixed as a catalyst, and the mixture was mixed with the same weight of phenoxyethyl acrylate as a diluent and reacted at 70 ° C. for 2 hours.

[0070]

(Equation 1)

Thereafter, 0.4 mol of 2-HEMA was added, and the mixture was further reacted at 70 ° C. for 2 hours to synthesize a urethane methacrylate polymer (P-1). The average molecular weight of this prepolymer was 52,000 as a result of GPC measurement.

A methacrylate polymer (P-2) having an acrylic rubber skeleton was synthesized by the following method. 70 parts by weight of butyl acrylate, 20 parts by weight of acrylonitrile, 5 parts by weight of 2-ethylhexyl methacrylate, and 0.5 part by weight of P-methane hydroperoxide are mixed and polymerized in toluene to give a weight average molecular weight of 70,00.
No. 0 acrylic rubber polymer was obtained.

Further, 1.25 parts by weight of 2-isocyanatoethyl methacrylate and 0.02 parts by weight of dibutyltin dilaurate were added, and 20 parts by weight of isononyl acrylate was added to the product obtained by converting the side chain hydroxyl group to a methacryl group. By evaporating only toluene under heating and reduced pressure, an acrylic rubber polymer (P-2) having a methacryl group in a liquid side chain was synthesized.

A methacrylate polymer (P-3) having an ethylene-acryl rubber skeleton was synthesized by the following method. It has a glycidyl group on the side chain and has a weight average molecular weight of 10
50 parts by weight of 10,000 ethylene-acryl rubber (Esprene MGR4102 EAA-552 manufactured by Sumitomo Chemical Co., Ltd.) is dissolved in 100 parts by weight of phenoxyethyl methacrylate, and 4 parts by weight of methacrylic acid and 1.5 parts by weight of triphenylphosphine are compounded. Then, the mixture was reacted at 90 ° C. for 3 hours to synthesize an ethylene-acryl rubber polymer (P-3) having a methacryl group in a liquid side chain in which a side chain glycidyl group was converted into a methacryl group.

Production of resin acrylate oligomer P-4 for comparative example. Using a diol having a structural average molecular weight of 500 represented by Formula 1, an oligomer was synthesized in the same manner as in the production of P-1. As a result of GPC measurement of this oligomer, the average molecular weight was 9,000.
It was 0. This oligomer was designated as P-4.

Examples 1 to 5 and Comparative Examples 1 to 3 (Study on surface curability depending on the type of photoinitiator) Using the component (A) obtained above, a sealant composition was produced. The formulations and amounts are as shown in Table 1.

[0077]

[Table 1]

However, in the table, IC1700; bis (2,6-dimethoxybenzoyl)
Mixture of -2,4,4-trimethyl-pentylphosphine oxide and 2-hydroxy-2-methyl-1-phenylpropan-1-one IC1800; bis (2,6-dimethoxybenzoyl)
Mixture of -2,4,4-trimethyl-pentylphosphine oxide and 1-hydroxycyclohexylphenyl ketone Lucirin TPO; 2,4,6-trimethylbenzoyldiphenylphosphine oxide DC1173; 2-hydroxy-2-methyl-1-phenylpropane -1-one IC651; 2,2'-dimethoxy-2-phenylacetophenone BIE; benzoin butyl ether DMBI; P-dimethylaminobenzoic acid isoamyl ester (tertiary amine compound).

Each prepared resin was put into a diameter of 32φ × a height of 9 m.
m of a polyethylene container, and was irradiated with 3000 mj / cm ² of ultraviolet light using a UV lamp. Also,
Visible light was irradiated for 60 seconds using a xenon lamp to cure the sealant composition. Then, the cured state of the surface and the bottom of the cured product was confirmed. Table 2 shows the results.

[0080]

[Table 2]

Examples 6 to 8 and Comparative Examples 4 to 6 Further, as shown in Table 3, sealing compositions were formulated. Also,
Comparative Example 6 includes three bond 12 which is a silicone RTV.
88 were used.

[0082]

[Table 3]

The sealant composition obtained above was measured as described below. (Rubber physical properties after curing) Area: 110 × 80 mm, depth 2
of each sealant composition blended in a fluororesin mold having a thickness of 2 mm, and treated with a silicone release agent from above.
A T film was covered, and light irradiation was performed using a 100 W halogen lamp for 2 minutes to form a rubber sheet. The prepared rubber sheet was punched out into a No. 3 dumbbell of JIS-K-6301 (physical test method for vulcanized rubber), and JIS-K-6
The hardness was measured with a type A along with 301, and the elongation and tensile strength were measured. Silicone RTV Three Bond 128
Sample No. 8 was poured into a mold having a depth of 2 mm and cured at room temperature for one week.

(Shearing Adhesive Force and Followability) Size 100 ×
25 × 1.0 mm cold-rolled steel sheet (JIS-G-314)
Each sealant composition was applied to a test piece of 1-SPCC-SB) by providing a weir around the area so as to have an area of 25 × 10 mm and a thickness of 2 mm, and was irradiated with various lamps for 1 minute. Next, another test piece was bonded and left for 48 hours at room temperature, and the shearing adhesive strength was measured at a pull rate of 50.
The measurement was performed at a rate of mm / min. At this time, the amount of deformation (elongation) until the test piece was broken was measured. Silicone RTV Three Bond 1288 was measured after curing at room temperature for one week.

(Initial Sealability) A pressure-resistant container having a shape similar to that of the pressure-resistant test container of JIS-K-6820 has 3
The sealant composition was applied with a bead diameter of mm, and irradiated with light for 60 seconds using various lamps. The average thickness of the bead at that time was 3 mm on average. The other bead surface was put on the hardened bead, adjusted using a spacer so as to have a clearance of 2 mm, and tightened with an M8 bolt with a tightening torque of 100 kgf · cm. Immediately after the fastening, the flange was assembled to a seal test apparatus, and turbine oil was pressurized as a seal medium at a pressure increasing rate of 5 kgf / cm ² every 30 seconds, and the pressure value when a leak occurred was measured. Immediately after the application of silicone RTV Three Bond 1288, the flange was assembled and the measurement was carried out as it was.

(Pressure resistance after 48 hours) The initial sealing test was carried out except that the flange was assembled and left at room temperature for 48 hours.

The results are shown in Table 4.

[0088]

[Table 4]

[0089]

According to the method of forming a gasket using the sealant composition of the present invention, a gasket bead having an arbitrary thickness is formed on a flange and only the surface is in an uncured state, and the inside has an elongation percentage. Since it can be completely cured in a short time at room temperature into an excellent elastomer, excellent initial pressure resistance can be obtained due to the compression and restorability of the gasket immediately after assembly, and the uncured layer on the surface is cured in a short time at room temperature by anaerobic curing. Therefore, when the gasket layer is used for a long period of time, there is no fear of leakage of the contact surface due to settling of the gasket layer, and excellent followability to the movement of the flange surface can be obtained.

Further, since the thickness of the gasket layer can be adjusted to an arbitrary thickness of 0.5 to 20 mm, the thickness of the gasket layer can be freely designed according to the amount of displacement of the flange surface, and the gasket layer is thick. Therefore, an excellent anti-vibration effect can be expected. Also, when the flange surface is disassembled for maintenance or disposal, there is an effect that the flange surface is easily disassembled depending on the initial elongation.

Since the photo-curable and anaerobic curable compositions used in the present invention do not cure for a long time even when exposed to the atmosphere like silicone RTV, the clogging of the tip of the nozzle during the idle time of the line operation is not possible. It is possible to expect an excellent effect on process management that the work can be transferred to the next process without any problem even if the applied work is left uncured or irradiated with light for a long time.

Further, even when the thickness of the gasket is increased, the sealing agent is not broken even in the lateral movement between the flanges due to the excellent followability, and the adhesion to the flange is not impaired. The sealing performance can be demonstrated.

[0093]

[Brief description of the drawings]

FIG. 1 is a diagram in which a sealant used in the present invention is applied to a flange and irradiated with light.

FIG. 2 is a view when a flange is assembled.

[Explanation of symbols]

 1) Uncured surface layer 2) Cured rubber layer 3) Flange

Embedded image

Claims (6)

[Claims] (A) having at least two (meth) acryloyl groups in one molecule and having a weight average molecular weight of 1
(B) a (meth) acrylate monomer having a glass transition point of room temperature or lower. (C) Anaerobic curing catalyst (D) Photocuring catalyst A liquid sealing composition comprising the above components (A), (B), (C) and (D) is applied on one of the surfaces to be sealed in a range of 0.5 mm to
The liquid sealant composition is applied in a bead shape with an application thickness of 20 mm, and the surface of the liquid sealant composition is left uncured while the inside is irradiated with an appropriate amount of light to cure the rubber-like material. A method of forming a gasket, comprising: forming a gasket having a two-layer structure of an elastic inner layer, and anaerobically curing an uncured sealant by pressing a surface to be sealed facing the gasket. 2. The method according to claim 1, wherein the component (A) is (A-1)
Having two or more (meth) acryloyl groups in the molecule,
Acrylic rubber having a weight average molecular weight of 10,000 to 200,000, or (A-2) having at least two (meth) acryloyl groups in one molecule and having a weight average molecular weight of 10,000 to 200,000
The method for forming a gasket according to claim 1, wherein the gasket is 200,000 ethylene-acrylic rubber. 3. The acrylic rubber or ethylene-acrylic rubber of the component (A-1) or (A-2) has a first reactive group, and undergoes a condensation reaction and an addition reaction with the first reactive group. The method for forming a gasket according to claim 2, wherein the gasket is obtained by reacting a second reactive group capable of being bonded with a compound having a (meth) acryloyl group. 4. The method according to claim 1, wherein the first reactive group is a hydroxyl group, a glycidyl group,
The method according to claim 3, wherein the second reactive group is selected from a carboxyl group, and the second reactive group is selected from an isocyanate group, a carboxyl group, and a glycidyl group. 5. The method for forming a gasket according to claim 1, wherein the photo-curing catalyst is a curing catalyst that generates radicals upon irradiation with visible light. 6. The method according to claim 1, wherein the photo-curing catalyst is an acylphosphine oxide-based initiator.