JPS6183277A - Elastic sealant - Google Patents

Abstract

PURPOSE:To provide a two-pack urethane-base elastic sealant with excellent weathering and heat resistance, durability and workability, consisting mainly of polyoxyalkylene or acrylic isocyanate component and containing a specified mixt. as hardener. CONSTITUTION:The elastic sealant consists mainly of (A) polyoxyalkylene isocyanate with terminal isocyanate groups obtained by interaction of polyoxyalkylene polyol and organic diisocyanate or (B) acrylic isocyanate which is alkyl (meth)acrylate based copolyisocyanate having about one isocyanate group on average at the terminal and average one or more isocyanate groups within the molecule and contains, as hardener, a mixt. of (a) polyosyalkylene polyol with a number-average M. W. of 1,000 or higher and (b) low-molecular acrylic copolymer containing average one functional group capable of reacting with an isocanate group at the terminal and average 1.5-4.0 functional groups in the molecule and having a number-average M. W. of 6,000 or higher.

Description

[Detailed description of the invention] [Industrial application field] This invention relates to an elastic sealant with excellent weather resistance.

[Conventional technology]

Sealants filled into the joints of buildings must have elastic properties that allow them to expand and contract in response to thermal changes in the building materials that make up the joints. It is desirable that the material does not contain any scattered substances.

Such a sealant is mainly composed of a prepolymer having an isocyanate group at the molecular end obtained by reacting a polyoxyalkylene polyol with an organic diisocyanate, a polyoxyalkylene polyol or polyamines as a curing agent, and other fillers as necessary. Urethane sealants containing softeners, stabilizers, etc. are used.

However, such conventional urethane sealants have problems in weather resistance, and have the drawback that cracks occur on the sealant surface when exposed outdoors for a long period of time.

On the other hand, recently, acrylic sealants containing a low molecular weight (meth)acrylic acid alkyl ester copolymer having a functional group as a main component have become known. This type of sealant has the advantage of being excellent in weather resistance, durability, heat resistance, etc. However, this acrylic sealant has the disadvantage that it is difficult to adjust the workability of the sealant and the properties of the cured sealant, particularly the elastic properties such as modulus and elongation. That is,
In order to obtain a cured sealant with low modulus and high elongation, it is necessary to increase the molecular weight of the (meth)acrylic acid alkyl ester-based low molecular weight copolymer, but increasing the molecular weight increases the viscosity and reduces workability. Another drawback is that the surface of the cured product may become sticky.

[Problem that the invention seeks to solve]

This invention solves the problem that with acrylic sealants that have excellent weather resistance, it is difficult to adjust the workability, low tackiness and elastic properties of the cured sealant surface, etc., as mentioned above. The objective is to obtain an acrylic elastic sealant that has sufficient elastic properties for filling the joints of objects, has a low adhesive surface on the cured product surface, is weather resistant, and is easy to work with. .

[Means for solving problems]

As a result of intensive research to solve the above problems, the inventors discovered that the main ingredient (isocyanate component) of two-component urethane
It was also discovered that by using a polyoxyalkylene component and an acrylic component in combination as a curing agent (polyol component), an elastic sealant that is useful in the T industry and that solves the above problems can be obtained, and the present invention has been made. I was able to complete it.

That is, the present invention provides a polyoxyalkylene isocyanate component having an isocyanate group at the end of the molecule obtained by reacting a polyoxyalkylene polyol with an organic diisocyanate, or an isocyanate group having an average of about one isocyanate group at the end of the molecule and an arbitrary position within the molecule. The main ingredient is a (meth)acrylic acid alkyl ester-based low molecular weight copolymer isocyanate component (hereinafter referred to as acrylic isocyanate component) having an average of one or more copolymer isocyanates, and has a number average molecular weight of 1,
Polyoxyalkylene polyol with a number average molecular weight of 6,000 or more and has an average of about 1 functional group at the end of the molecule and 1.5 to 4.0 functional groups at any position within the molecule that can react with polyoxyalkylene polyols of 6,000 or more and isocyanate groups. A mixture of (meth)acrylic acid alkyl ester-based low molecular weight copolymer C (hereinafter referred to as (meth)acrylic acid alkyl ester-based low molecular weight copolymer, all of which are abbreviated as acrylic low molecular weight copolymer)) is used as a curing agent. This relates to an elastic sealant.

[Structure and operation of the invention]

As the main ingredient in the elastic sealant of the present invention, a polyoxyalkylene isocyanate component or an acrylic isocyanate component may be used alone, or both may be used as a mixture in any proportion. On the other hand, as a curing agent, a mixture of a polyoxyalkylene polyol and a low molecular weight acrylic copolymer is used.

According to this, the ratio of the polyoxyalkylene component and the acrylic component in the sealant can be changed over a wide range depending on the purpose, and the ratio of the polyoxyalkylene isocyanate component or acrylic isocyanate component of the base agent to the polyoxyalkylene component of the curing agent can be changed over a wide range. By combining the oxyalkylene polyol and the low molecular weight acrylic copolymer, the sealant can have various properties.

The polyoxyalkylene isocyanate component used as the main ingredient can be obtained by reacting an organic diisocyanate with a polyoxyalkylene polyol obtained by polymerizing a polyhydric alcohol and an alkylene oxide. The number average molecular weight of this polyoxyalkylene polyol is preferably about 300 to 6,000.

Examples of the polyhydric alcohol include ethylene glycol, propylene glycol, glycerin, pentaerythritol, and trimethylolpropane, but diols such as ethylene glycol and propylene glycol, and triols such as glycerin are preferably used.

Examples of the above alkylene oxides include propylene oxide, ethylene oxide, butylene oxide, etc., and these may be used alone or in a mixture of two or more.

There are no particular restrictions on the organic diisocyanate used to introduce isocyanate groups into the terminals of this polyoxyalkylene polyol, but diisocyanates that do not cause yellowing of the cured sealant, such as 3-bisisocyanate methylcyclohexane and isophorone diisocyanate; It is preferable to use Others 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate,
Examples include 4,4'-diphenylmethane diisocyanate, xylylene diisocyanate, hexamethylene diisocyanate, and the like.

In addition, the acrylic isocyanate component used as the main ingredient is a) reacted with the isocyanate group in the presence of a polymerization initiator having a functional group capable of reacting with the isocyanate group or a chain transfer agent having a functional group capable of reacting with the isocyanate group. An unsaturated monomer having one functional group that can be
monomer) and b) a trophic mixture (hereinafter referred to as F,
An acrylic polymer having on average about 1 functional group at the end of the molecule and on average 1 or more, usually up to 2 functional groups at any position within the molecule, which can react with the isocyanate group obtained by copolymerizing B monomer. It is obtained by reacting a molecular weight copolymer with an organic diisocyanate.

Polymerization initiators with functional groups that can react with the above-mentioned isocyanate groups include those with carboxyl groups, hydroxyl groups, etc. Specifically, azobiscyanovaleric acid, oxalic acid peroxide, azobiscyanopene Examples include tanol.

In addition, chain transfer agents with functional groups that can react with isocyanate groups include chain transfer agents with carboxyl groups, hydroxyl groups, amino groups, etc., specifically thioglycolic acid, 2-mercap], acetic acid, Examples include 2-mercaptoethanol and 2-aminoethanethiol.

During copolymerization, the above polymerization initiator and the above chain transfer agent may be used together, or either one of them may be used. The amount of these used is such that an average of about one functional group capable of reacting with the isocyanate group derived from the above polymerization initiator or chain transfer agent is introduced into the molecular end of the acrylic low molecular weight copolymer, and this copolymer is 0.3 parts by weight per 100 parts by weight of b monomer so that the average molecular weight of
-20 parts by weight. The reason why an average of about one functional group capable of reacting with an isocyanate group is introduced at the end of the molecule is to obtain good results in the elastic properties of the cured sealant.

Next, the above monomer a is an unsaturated monomer having a carboxyl group, a hydroxyl group, etc., and specifically, acrylic acid,
Examples include methacrylic acid, maleic acid, 2-hydroxyethyl acrylate, and 2-hydroxyethyl methacrylate.

In addition, the above b monomer refers to acrylic acid or methacrylic acid having 2 to 14 carbon atoms, such as ethyl, n-butyl, isobutyl, 1-ethylpropyl, 2-methylpentyl, 2-ethylbutyl, 2-ethylbutyl, etc. 100 to 50% by weight of one or more alkyl esters and other monomers copolymerizable with these, such as vinyl acetate, vinyl propionate, acrylonitrile, methyl methacrylate, styrene, acrylamide. It contains 0 to 50% by weight of 1 and the like. If the amount of this copolymerizable monomer exceeds 50% by weight, the weather resistance will decrease, which is not preferable.

The ratio of the a monomer to the b monomer is determined by taking into account the degree of polymerization and the polymerizability ratio within the range where the amount of the a monomer used is 1/10 to 11,500 mol of the amount of the b monomer used. The acrylic low molecular weight copolymer has at any position within the molecule an average of 1 or more functional groups capable of reacting with the isocyanate group derived from the a monomer, preferably 1.0 to 2. It is determined that 1.8 pieces will be introduced.

The above-mentioned low molecular weight acrylic copolymer is produced by copolymerizing a predetermined amount of a monomer and a monomer b in the presence of a predetermined amount of a polymerization initiator or a chain transfer agent according to a conventional method. It can be obtained by Polymerization is radical polymerization, and conventional polymerization initiators such as henzoyl peroxide and α・α′-azobisisobutyronitrile are used. A conventional initiator is not necessary.

It is preferable to perform bulk copolymerization without using a solvent, and if unreacted monomer remains, it will cause odor during sealant application and eye discoloration after application. Polymerization conditions such as temperature and 2 hours are adjusted so that no residue remains.

An acrylic isocyanate component can be obtained by reacting the acrylic low molecular weight copolymer thus obtained with an organic diisocyanate. As the above-mentioned organic diisocyanate, those exemplified for the polyoxyalkylene isocyanate component can be similarly used. The number average molecular weight of this acrylic isocyanate component is not particularly limited as long as it is liquid, but it is preferably from 1,500 to 6,000.

The polyoxyalkylene polyol, which is one component of the curing agent in the elastic sealant of this invention, is obtained by copolymerizing the same polyhydric alcohol and alkylene oxide as exemplified for the polyoxyalkylene isocyanate component of the main ingredient. It is. The number average molecular weight of this polyoxyalkylene polyol is 1,000 or more, preferably 2,000 to 6,000.

In addition, the acrylic low molecular weight copolymer, which is another component of the curing agent, can be obtained using the same method as the method used to obtain the acrylic low molecular weight copolymer described for the acrylic isocyanate component of the main ingredient. Using a polymerization initiator and/or a chain transfer agent having a functional group capable of reacting with an isocyanate group, and the monomers a and b, an average of about one functional group capable of reacting with an isocyanate group is present at the end of the molecule. The amount of the polymerization initiator or chain transfer agent having the above-mentioned functional group and the monomer a so that it has an average of 1.5 to 4.0, preferably 1.8 to 3.5, at any position in the This can be obtained by adjusting, etc. However, the number average molecular weight of this copolymer is 6,000 or more, preferably 7,000
00 to 25,000.

The reason why the average number of functional groups per molecule contained in the above copolymer is set to a total of 2.5 to 5.0 is that when the number of functional groups is less than 2.5, the surface of the cured sealant This is because if the number exceeds 5.0, the modulus of the cured sealant becomes too high. Furthermore, it is necessary to introduce about one functional group on average at the end of the molecule out of the number of functional groups mentioned above, and this is for the same reason as described for the copolymer in the main ingredient.

The blending ratio of the two components in the curing agent is 10% by weight or more of polyoxyalkylene polyol, usually 20 to 70% by weight.
It is preferable to adjust the amount to % by weight. This is because the acrylic low molecular weight copolymer used in combination with the above polyol has a number average molecular weight i of 16,000 or more and has a high viscosity, but if 10% by weight or more of the above polyol, which has a low viscosity, is mixed, it will be explained later. This is because when various additives are blended, the viscosity of the curing agent blended system can be kept low, resulting in improved workability.

As mentioned above, the polyoxyalkylene polyol in the curing agent in the elastic sealant of this invention has a number average molecular weight of 1,000 or more, and the acrylic low molecular weight copolymer has a number average molecular weight of 6,000 or more. do. This is due to the following reason.

That is, the polyoxyalkylene isocyanate component and the acrylic isocyanate component used as the main ingredients are obtained by reacting an organic diisocyanate with a polyoxyalkylene polyol and a low molecular weight acrylic copolymer, respectively, so they have relatively low molecular weights. The viscosity tends to be higher than that before reaction. Therefore, from the viewpoint of the workability of the sealant, those having a relatively low molecular weight are used as the main ingredients, but these are not preferable from the viewpoint of the properties of the sealant after curing. Therefore, by defining the molecular weight of the curing agent as shown in the following, it is possible to prevent the crosslinking density of the cured sealant from increasing, and to provide the sealant with sufficient elastic properties.

The ratio of the polyoxyalkylene component to the acrylic component in the elastic sealant of this invention can be varied over a wide range depending on the purpose, but usually the acrylic component is 15 to 95% of the total amount of the base agent and curing agent. It is preferable to adjust the amount to % by weight. If the acrylic component in the sealant is too small, the properties of the sealant as an acrylic elastic body will be low and the weather resistance will be poor, which is not preferable. Further, if the amount is too large, the viscosity of the sealant increases and workability decreases, which is not preferable.

In addition, the blending ratio of the base agent and curing agent in the elastic sealant of the present invention is usually such that the amount of functional groups capable of reacting with isocyanate groups in the curing agent is 0.8 to 1.2 equivalents per 1 equivalent of isocyanate groups in the base agent. It is better to make it happen.

The elastic sealant of the present invention can contain fillers and catalysts required for general sealants. Furthermore, pigments, anti-aging agents, anti-mold agents, antioxidants, ultraviolet absorbers, ozone deterioration inhibitors, thixotropic agents, etc. can be added as necessary.

The above-mentioned fillers improve the strength of the cured sealant, and include, for example, calcium carbonate, silica powder, talc, glass powder, titanium oxide, and the like. The amount added is preferably 30 to 200 parts by weight per 100 parts by weight of the curing agent. Therefore, it is undesirable.

Further, as the catalyst, organometallic compounds such as dibutyltin dilaurate, monobutyltin oxide, and dioctyltin dilaurate, and amine derivatives such as triethylenediamine, triethylenetetramine, and diaminodiphenylmethane can be used. These addition amounts are hardening agent 1
The amount is 0.01 to 5 parts by weight based on 0.00 weight.

The elastic sealant of the present invention constructed as described below has the advantage that it has good workability during construction and does not cause eye loss after construction. Furthermore, since the sealant after curing has the characteristics of an acrylic elastic material, it has excellent weather resistance, durability, and heat resistance, and easily follows changes in joint width, preventing cracks from forming orally. Never. Furthermore, the surface of the cured sealant does not become sticky, and therefore there is less staining due to adhesion of dust and the like.

〔Effect of the invention〕

As described above, the elastic sealant of the present invention is a two-component urethane type and has the properties of an acrylic elastic material, so it has significantly improved weather resistance, excellent durability and heat resistance, and has a hardening agent. or as a raw material for the main agent composition.
By using a low-molecular-weight acrylic copolymer that has a specific number of functional groups that can react with isocyanate groups at the end of the molecule and at arbitrary positions within the molecule, and by using this in combination with a polyoxyalkylene component. , low hardness.

It satisfies the characteristics required for architectural sealants, such as low modulus and high elongation.

In addition, in particular, because the curing agent for the main resin is a mixture of the above-mentioned low-molecular-weight acrylic copolymer and a polyoxyalkylene polyol whose viscosity is lower than that, even though the molecular weight of the above-mentioned copolymer is relatively high, The viscosity of the sealant can be easily adjusted without using a solvent, so workability during construction can be improved without degrading the properties of the elastic sealant, and it does not cause eye loss after construction. Furthermore, by setting a relatively large number of functional groups in the copolymer, which is one component of the curing agent, to improve curing properties, the sealant can be used even though the molecular weight of this copolymer is high. There is no need to worry about the surface of the cured product becoming sticky and reducing its staining properties.

〔Example〕

Next, examples of this invention will be described. In the following, parts mean parts by weight. Moreover, the term "molecular weight" means the number average molecular weight, and the term "%" means weight %.

Example 1 100 parts of n-butyl acrylate, 10 parts of acrylonitrile
1.5 parts of acrylic acid, and 1.2 parts of thioglycolic acid.

30% of this blended composition was placed in a four-hole flask, and the contents were heated to 70° C. while stirring and purging the inside of the flask and flask with nitrogen. After replacing with nitrogen for about 60 minutes, α
- When 0.1 part of α'-azobisisobutyronitrile was added, heat generation started immediately. After this heat generation has subsided, 0.2 part of α・α′-azobisisobutyronitrile is added to the remainder of the above-mentioned composition and gradually added to the flask using a dropping funnel over a period of about 3 hours. added. The point at which no heat generation was observed thereafter was defined as the end point of polymerization.

The acrylic low molecular weight copolymer thus obtained has a polymerization rate of 100%, a viscosity of 500 poise (30°C, 2 rpm) measured by a B-type rotational viscometer, and a molecular weight of 10,000.1 molecules measured by vapor pressure osmosis. The number of carboxyl groups per is 2
．． It was 93.

After adding 40 parts of polypropylene glycol (molecular weight 3,000) to 100 parts of this copolymer and mixing uniformly, 130 parts of calcium carbonate, 30 parts of titanium dioxide, and Disparon 360ON (flit Honkasei Honkarai company's polyether ether type) 2 parts of surfactant) and 0.5 part of dibutyltin dilaurate were mixed together in a kneader and then further kneaded with three rolls to obtain a curing agent combination system for the elastic sealant of the present invention.

As a main ingredient, a polyoxyalkylene isocyanate component obtained by reacting a polyoxyalkylene polyol with an organic diisocyanate (Takenate L manufactured by Narita Pharmaceutical Co., Ltd.)
-1032, isocyanate group content 2.85%), and 100 parts of the curing agent compounding system was blended with 40 parts of the main resin so that the curing agent was about 150 parts with respect to 100 parts of the main resin. It was made into a sealant.

Example 2 Acrylic was prepared in the same manner as in Example 1 using a blended composition consisting of 95 parts of n-butyl acrylate, 5 parts of styrene, 1.5 parts of 2-hydroxyethyl acrylate, and 0.6 parts of 2-mercaptoethanol. A low molecular weight copolymer was obtained.

This acrylic low molecular weight copolymer has a polymerization rate of 100% and B
The viscosity measured by a type rotational viscometer was 400 poise (30℃, 2r
pm), and the molecular weight determined by vapor pressure osmosis method was 8,000. The number of hydroxyl groups per molecule was 2.55.

After adding 50 parts of polypropylene glycol (molecular weight 4,000) to 100 parts of this copolymer and mixing uniformly, 150 parts of calcium carbonate, 20 parts of titanium dioxide, 3 parts of Disparon 360ON (mentioned above), and 0.2 parts of triethylenetetramine were added. 1 part and 0.2 part of carbon black were thoroughly kneaded using a kneader with 93 rolls to obtain a curing agent compounding system according to the present invention.

Main ingredients: 95 parts of n-butyl acrylate, 5 parts of styrene.
100 parts of an acrylic low molecular weight copolymer obtained by polymerizing in the same manner as in Example 1 using a blended composition consisting of 3 parts of 2-hydroxyethyl acrylate, and 2 parts of 2-mercaptoethanol were dehydrated. Later, 9 parts of 2,4-tolylene diisocyanate and 0.00 parts of dibutyltin dilaurate.
2 parts and reacted at 80°C for 5 hours to obtain an acrylic isocyanate component (isocyanate group content 2°0
5%) was used. The polymerization rate of the above acrylic low molecular weight copolymer is 100%, and the viscosity measured by a B-type rotational viscometer is 8.
Molecular weight measured by vapor pressure osmosis at 0 poise (30°C, 2 rpm) is 4,200. The number of hydroxyl groups per molecule is 2.08.
Met.

The elastic sealant of the present invention was prepared by blending 100 parts of a curing agent compounding system with 32 parts of the above acrylic isocyanate component so that the curing agent was about 145 parts with respect to 100 parts of the main agent.

Example 3 100 parts of n-butyl acrylate, 15 parts of acrylonitrile
An acrylic low molecular weight copolymer was obtained in the same manner as in Example 1 using a blended composition consisting of:

However, 7zobisci7novaleric acid was used as a polymerization initiator instead of α·α'-azobisisobutyronitrile.

This copolymer had a polymerization rate of 100%, a viscosity of 240 poise (30°C, 2 rpm) measured by a B-type rotational viscometer, and a molecular weight of 7,000 measured by vapor pressure osmosis.The number of carboxyl groups per molecule was 2.80. Ta.

After adding 20 parts of polypropylene glycol (molecular weight 3,000) to 100 parts of this polymer and mixing uniformly, 110 parts of calcium carbonate, 25 parts of titanium dioxide, 1.7 parts of Disparon 360ON (mentioned above), and 0.0 parts of dibutyltin dilaurate. 5 parts were mixed and sufficiently kneaded using a kneader with 13 rolls to obtain a curing agent blended system.

Using the same base ingredient as the base ingredient in Example 2, base ingredient 1
The elastic sealant of the present invention was prepared by blending 100 parts of a curing agent compounding system with 46 parts of this main ingredient so that the curing agent was about 100 parts per 00 parts.

Example 4 An acrylic resin was prepared in the same manner as in Example 1 using a blended composition consisting of 50 parts of n-butyl acrylate, 50 parts of ethyl acrylate, 2 parts of 2-hydroxyethyl acrylate, and 2 parts of 2-mercaptoethylamine. A molecular weight copolymer was obtained.

The copolymer has a polymerization rate of 98.5%, a viscosity of 800 boids (30'C, 2 rpm) measured by a B-type rotational viscometer, and a molecular weight of 13,000 measured by vapor pressure osmosis.The number of hydroxyl groups per molecule is 2. .03 and the number of amine groups was 1.05.

100 parts of polypropylene glycol (molecule i: 12,000) was added to 100 parts of this copolymer and mixed uniformly, followed by 200 parts of calcium carbonate, 30 parts of titanium dioxide, 4 parts of Disparon 360ON (mentioned above), and 0.2 parts of dibutyltin dilaurate. and 0.2 parts of carbon black were thoroughly kneaded using a kneader with 93 rolls to obtain a curing agent blended system.

Polyoxyalkylene obtained by dehydrating 100 parts of polypropylene glycol with a molecular weight of 4,000 as a main ingredient, adding 10 parts of 1,3-bisisocyanate cyclohexane and 0.005 parts of dibutyltin dilaurate, and reacting at 80°C for 5 hours. This invention was prepared by blending 126 parts of the base resin with 100 parts of the curing agent so that the curing agent was approximately 58 parts per 100 parts of the base resin. It was made into an elastic sealant.

Regarding the elastic sealants obtained in Examples 1 to 4 above,
When characteristics were evaluated based on JIS-A-5758, the slump of all sealants was Qmm, and there was no staining property. Furthermore, the extrudability and tensile adhesion properties were as shown in the following table.

Furthermore, when the cured products of the elastic sealants of Examples 1 to 4 were subjected to an outdoor exposure test (6 months), no surface cracks were found in any of them.

As a comparative example, an outdoor exposure test (for 6 months) of the cured product was conducted on a sealant formulated in the same manner as in Example 1 using only polypropylene glycol (molecular weight 3,000) as the curing agent. It was observed that many cracks were formed and the weather resistance was poor.

Claims (1)

[Claims] (1) A polyoxyalkylene isocyanate component having an isocyanate group at the end of the molecule obtained by reacting a polyoxyalkylene polyol with an organic diisocyanate, or an average of about 1 isocyanate group at the end of the molecule and an average of 1 isocyanate group at any position within the molecule. have more than one (meta)
Acrylic acid alkyl ester based low molecular weight copolymer isocyanate component is the main ingredient, polyoxyalkylene polyol with a number average molecular weight of 1,000 or more and an isocyanate group have an average of about 1 functional group at the end of the molecule and any arbitrary group within the molecule. An elastic sealant containing, as a curing agent, a mixture with a (meth)acrylic acid alkyl ester-based low molecular weight copolymer having a number average molecular weight of 6,000 or more and having an average of 1.5 to 4.0 at the position of .