JPS61103978A - One-pack type elastic sealant - Google Patents

Abstract

PURPOSE:The titled sealant having improved weather resistance, etc., comprising an isocyanate prepolymer consisting of a mixture of an isocyanate group- containing polyoxyalkylene prepolymer and a specific acrylic prepolymer, as a main component. CONSTITUTION:100pts.wt. isocyanate prepolymer consisting of (A) a polyoxy alkylene prepolymer obtained by reacting a polyoxyalkylene polyol having >=400 number-average molecular weight with an organic diisocyanate compound and (B) an acrylic prepolymer obtained by reacting (i) an unsaturated monomer having a functional group capable of being reacted with an isocyanate group with (ii) an unsaturated monomer shown by the formula (R1 is H, or methyl; R2 is 2-14C alkyl) in the presence of a polymerization initiator and/or a chain transfer agent is blended with 0.005-10pts.wt. reaction promoting catalyst, and 30-250pts.wt. filler, and the blend is dehydrated, to give the aimed sealant.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] This invention relates to a one-component elastic sealant that can be cured by moisture in the air and is useful for filling joints in buildings.

[Conventional technology]

Sealants filled into the joints of buildings, etc. must have elastic properties that allow them to expand and contract in response to changes in the building materials that make up the joints due to thermal effects, especially low modulus and high elongation. Something with excellent sex is desired.

Conventionally, polymers that can be cured by moisture in the air and are mainly composed of prepolymers with isocyanate groups at the molecular ends obtained by reacting polyoxyalkylene polyols with an organic diisocyanate compound and are blended with fillers, softeners, etc. Although liquid type urethane sealants are known, such conventional urethane sealants have problems in weather resistance and have the disadvantage that cracks occur on the surface of the sealant when exposed outdoors for a long period of time.

In contrast, recently, one-component type prepolymers containing free isocyanate groups in the molecule, which are obtained by introducing isocyanate groups into low-molecular-weight (meth)acrylic acid alkyl ester copolymers, have been developed. Acrylic elastic sealants have become known. This type of sealant has advantages such as excellent weather resistance, durability, heat resistance, and colorability.

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. In other words, in order to make the sealant cured product have low modulus and high elongation, it is necessary to lengthen the molecular chain between the isocyanate groups in the acrylic prepolymer molecule. The molecular weight of the acrylic prepolymer is increased within a range that does not reduce the workability of the acrylic prepolymer, so that the isocyanate group content (% by weight) per molecule is reduced.

However, since the position of the isocyanate group introduced into the acrylic prepolymer is unspecified, it may not be possible to obtain the desired elastic properties even if the molecular weight is increased as described above. If the molecular weight of the acrylic prepolymer is made higher, it is easier to obtain the desired elastic properties, but this is not recommended for sealants.

The viscosity of this product becomes too high, reducing 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 and the low tackiness and elastic properties of the surface of the cured sealant, as described above. The purpose of the present invention is to obtain a one-component elastic sealant that has sufficient elastic properties for filling joints, has a cured product surface with low tackiness, has excellent weather resistance, and has excellent workability.

[Means for solving problems]

As a result of intensive studies to achieve the above object, the inventors found that when a specific polyoxyalkylene prepolymer having a free isocyanate group in the molecule and a specific acrylic prepolymer are used together in a specific ratio, The inventors discovered that it was possible to obtain an industrially useful elastic sealant that solved the above-mentioned problems, and thus completed the present invention.

That is, this invention comprises: A) reacting an organic diisocyanate compound with a polyoxyalkylene polyol having a number average molecular weight of 400 or more at a ratio of 1.8 to 2.3 equivalents of isocyanate groups per equivalent of hydroxyl group in the polyol; Obtained polyoxyalkylene prepolymer 10
~80% by weight, B) a) an unsaturated monomer having a functional group capable of reacting with an isocyanate group, and b) the following general formula;
C) a functional group that can react with isocyanate 5, In the presence of a polymerization initiator and/or chain transfer agent having
Organic diisocyanate is added to an acrylic low molecular weight copolymer that has an average of about 1 functional group at the end of the molecule and 1.6 to 4.0 functional groups at any position within the molecule that can react with the isocyanate group obtained by copolymerization. 90 to 20% by weight of an acrylic prepolymer obtained by reacting a compound at a ratio of 1.8 to 2.3 equivalents of isocyanate groups per equivalent of functional groups capable of reacting with isocyanate groups in the copolymer. To 100 parts by weight of isocyanate brepolymer consisting of,
0.005 to 10 parts by weight of reaction promoting catalyst and 30 to 2 parts by weight of filler
This relates to a one-component elastic sealant prepared by blending 50 parts by weight of the blend with 50 parts by weight and dehydrating this blend.

[Structure and operation of the invention]

The polyoxyalkylene prepolymer comprising the component A of the present invention is prepared by reacting an organic diisocyanate compound with a polyoxyalkylene polyol having a number average molecular weight of 400 or more, preferably 400 to 6,000, as measured by an end group quantitative method. can be obtained. If the number average molecular weight of the polyol is less than 400, it is unsuitable because the cured sealant product has a high modulus and a low elongation.

Furthermore, if the number average molecular weight is too high, the viscosity of the sealant will increase and the workability of the sealant will decrease, which is not preferable.

This polyol is usually obtained by reacting a polyhydric alcohol with an alkylene oxide. Examples of the polyhydric alcohol include ethylene glycol, propylene glycol, glycerin, pentaerythritol, and trimethylolpropane, but preferably diols such as ethylene glycol and propylene glycol,
Triols such as glycerin are used. Further, examples of the alkylene oxide include propylene oxide, ethylene oxide, butylene oxide, etc., and these may be used alone or in a mixed system of two or more types.

The organic diisocyanate compound to be reacted with the polyol is not particularly limited as long as it can introduce an isocyanate group into the polyol.
'-diphenylmethane diisocyanate, 3,3'-dimethyl-4,4'-diphenylmethane diisocyanate, 4,4'-cyclohexylmethane diisocyanate,
These include toluylene diisocyanate, hexamethylene diisocyanate, xylylene diisocyanate, p-phenylene diisocyanate, m-phenylene diisocyanate, isophorone diisocyanate, 1,3-bisisocyanatemethylcyclohexane, 4,4'-isopropylidenecyclohexyl isocyanate, etc. It can be used as a mixture of two or more types.

Among these organic diisocyanate compounds, especially 1
- 3-Bisisocyanate Methylcyclohexane and isophorone diisocyanate are particularly preferred because they provide a cured sealant with excellent non-yellowing properties and excellent heat resistance.

The amount of this organic diisocyanate compound to be used is 1.8 to 2.0% of isocyanate groups per 1 equivalent of hydroxyl group of the polyol.
There should be 3 equivalents, preferably 1.9 to 2.2 equivalents. Thereby, free isocyanate groups corresponding to the number of hydroxyl groups in the polyol can be introduced into the resulting polyoxyalkylene prepolymer.

If the amount used is less than 1.8 equivalents, the resulting polyoxyalkylene prepolymer will have a high molecular weight, resulting in high viscosity, or may gel in some cases. Both methods are unsuitable because the amount of the organic diisocyanate compound involved in the reaction increases, resulting in a higher modulus and lower elongation of the cured sealant.

The above-mentioned polyol and organic diisocyanate compound may be reacted according to a conventional method, and the reaction temperature and reaction time vary depending on the type of residual diisocyanate compound, but usually at a temperature in the range of room temperature to 150°C. The reaction may be allowed to proceed for several hours to several tens of hours. At this time, a catalyst such as dibutyltin dilaurate may be used if necessary.

In carrying out the above reaction, it is desirable to dehydrate the polyol in advance by heating under reduced pressure or the like to reduce its water content to 0.05% by weight or less.

The acrylic prepolymer consisting of component B of this invention is
Organic diisocyanate is added to an acrylic low molecular weight copolymer having an average of about 1 functional group at the end of the molecule and 1.6 to 4.0 functional groups at any position within the molecule that can react with isocyanate groups obtained by the method below. It can be obtained by reacting compounds.

The above acrylic low molecular weight copolymer comprises a) an unsaturated monomer having a functional group capable of reacting with an isocyanate group, and b
) The following general formula; % Formula % (However, R3 represents hydrogen or a methyl group, R2 represents an alkyl group having 2 to 14 carbon atoms) Unsaturated monomer, that is, (meth)acrylic acid alkyl ester and,
C) It is obtained by copolymerization in the presence of a polymerization initiator and/or chain transfer agent having a functional group capable of reacting with an isocyanate group.

The a component used here may be any unsaturated monomer having a functional group such as a carboxyl group, a hydroxyl group, or an amino group that can react with an isocyanate group. Specific examples include (meth)acrylic acid, 2 -Hydroxyethyl (
meth) acrylate, polyethylene glycol (meth)
Acrylate, polypropylene glycol (meth)acrylate, N-methylaminoethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, and the like.

In addition, for the b component #4mer, the alkyl group (R2) in the above general formula may be branched or linear, and specific examples of this alkyl group include ethyl, n
-butyl, isobutyl, 1-ethylpropyl, 1-methylpentyl, 2-methylpentyl, 3-methylpentyl, 1-ethylbutyl, 2-ethylbutyl, isooctyl, 3,5,5-trimethylhexyl, decyl, dodecyl, etc. be able to. If an alkyl group having more than 14 carbon atoms is used, a problem arises in the adhesiveness of the elastic sealant composition to joint materials such as building materials.

In the present invention, up to half of the component monomers mentioned above can be replaced with other copolymerizable unsaturated monomers. Specific examples of other copolymerizable unsaturated monomers include vinyl pyridine, vinyl ethers, (meth)acrylonitrile, methyl (meth)acrylate, N-N-dimethylaminoethyl (meth)acrylate, vinyl halides, Butadiene, chlorobrene, styrene, (meth)acrylic amide, vinylpyrrolidone, cyclohexyl (meth)acrylate, glycidyl (meth)acrylate, β-ethoxy (meth)acrylate, vinyl acetate, mono [2-hydroxyethyl-α-chloro( Examples include meth)acrylate coacid phosphate and fluoroalkyl(meth)acrylate.

The type and proportion of these other unsaturated monomers may be determined as appropriate depending on the purpose of use of the elastic sealant, but b
If the proportion of the component monomer in the total amount is more than half, the above-mentioned properties as an acrylic sealant may be impaired.

Furthermore, as the C component, 2. Either or both of a polymerization initiator having a functional group capable of reacting with an isocyanate group or a chain transfer agent having a functional group capable of reacting with an isocyanate group are used.

Examples of the polymerization initiator include azobiscyanovaleric acid, oxalic acid peroxide, and azobiscyanopentanol, which have a carboxyl group, hydroxyl group, etc. as a functional group that can react with an isocyanate group.

Examples of the chain transfer agent include thioglycolic acid, 2-mercaptoacetic acid, 2-mercaptoethanol, and 2-aminoethanethiol, which have a carboxyl group, hydroxyl group, amino group, etc. as a functional group that can react with an isocyanate group. It will be done.

Regarding the usage ratio of each of the above components, first, the polymerization initiator or chain transfer agent of component C has an average of about 1 functional group per molecule introduced into the terminal of the copolymer molecule that can react with the isocyanate group derived therefrom. Thus, it is generally used in an amount of 0.2 to 10 parts by weight per 100 parts by weight of component b monomer. In addition, the a component monomer is used in a ratio such that the total amount of this and the above C component is 115 to 11,500 molar ratio to the b component monomer, and within this range, the polymerizability ratio of itself and the polymerization Considering the degree of polymerization determined by the amount of initiator and chain transfer agent used, the number of functional groups capable of reacting with the isocyanate group derived from component C at any position within the copolymer molecule is on average 1.6 to 1. 4.0 pieces, preferably 1.7-3
．． In other words, the total amount of the functional groups derived from the C component and the functional groups derived from the C component is on average 2.6 to 5.0 per molecule, preferably 2.7 to 5. 4
．． The number is determined to be five.

The reason why the total number of functional groups per molecule contained in the copolymer is set to be 2.6 to 5.0 on average as described above is that the number of functional groups is set to be relatively large in this way. This is to contribute to the reticulation of the cured sealant product, prevent the surface of the cured product from becoming sticky, and obtain good results in improving stain resistance. When the number of functional groups is less than 2.6, such an effect cannot be expected; on the other hand, when it exceeds 5.0, drawbacks such as an excessively high modulus of the cured sealant product arise. Furthermore, it is necessary to introduce about one functional group on average at the end of the molecule, since good results can be obtained in the elastic properties of the cured sealant.

Copolymerization of the C component monomer and the b component monomer in the presence of the C component may be carried out according to a conventional method. A conventional polymerization initiator and/or chain transfer agent having no functional group capable of reacting with isocyanate groups is used.

For example, in a particularly preferred embodiment of the present invention, a chain transfer agent having a functional group capable of reacting with an isocyanate group in the molecule is used alone as component C; A conventional polymerization initiator without groups is required. Examples include benzoyl peroxide, lauroyl peroxide,
Examples include methyl ethyl ketone peroxide, azobisisobutyronitrile, and azobisvaleronitrile.

It goes without saying that these polymerization initiators contain a small amount of C component.

In addition, in this invention, when a polymerization initiator having a functional group capable of reacting with an isocyanate group in the molecule is used alone as the C component, that is, a chain transfer agent having a functional group capable of reacting with an isocyanate group in the molecule is not used at all. In general, a conventional chain transfer agent that does not belong to component C, that is, does not have a functional group capable of reacting with an isocyanate group in its molecule, is preferably used. Examples include carbon tetrachloride, carbon tetrabromide, n-butyl mercaptan, lauryl mercaptan, and the like. It goes without saying that it can also be used in these cases of chain transfer.

The amounts of the polymerization initiators and chain transfer agents that do not belong to component C as described above are within the normal usage range depending on their respective functions. The amount of the chain transfer agent may be determined as appropriate in the range of 1 to 2 parts by weight, and in the range of 0.1 to 15 parts by weight based on 100 parts by weight of component B monomer, depending on the type and amount of component C.

In such a copolymerization reaction, the use of a chain transfer agent that may or may not belong to component C facilitates polymerization control, so a solvent as a medium is not necessary. However, if particularly desired, n-hebutane , toluene, n-hexane,
Solvents such as dioxane, methyl ethyl ketone, methyl isobutyl ketone, ethyl acetate, and isopropanol may be used. Generally, a suitable polymerization temperature is in the range of about 50 to 95°C.

It has an average of about 1 functional group at the end of the molecule and 1.6 to 4.0 functional groups at any position within the molecule, which can react with the isocyanate i obtained in this way. The acrylic low molecular weight copolymer having an average total number of 2.6 to 5.0 pieces preferably has a number average molecular weight of 4,000 to 2s, ooo, as measured by vapor pressure osmosis. If this molecular weight is too low, the modulus of the cured sealant product will be high and the elongation will be low, which is undesirable. On the other hand, if it is too high, the viscosity of the sealant will be high and workability will be decreased, which is not preferred. 5. Such adjustment of the molecular weight can be easily carried out mainly by changing the type and amount of the chain transfer agent and by setting the polymerization time.

The organic diisocyanate compound is added to the acrylic low molecular weight copolymer obtained by the above method, and the amount of isocyanate groups is 1.8 to 2.3 equivalents, preferably 1.9 to 2.2 equivalents per equivalent of the functional group of the above copolymer. By reacting at a ratio such that acrylic prepolymers have free isocyanate groups introduced into the molecule according to the number of functional groups of the above-mentioned copolymer, it is possible to obtain an acrylic prepolymer. The type of organic diisocyanate compound used here and the reaction operation are exactly the same as in the case of obtaining the polyoxyalkylene prepolymer. The amount of the organic diisocyanate compound to be used is set as described above for the same reason as stated in the case of obtaining the polyoxyalkylene prepolymer.

In this invention, a polyoxyalkylene prepolymer consisting of the above component A and an acrylic prepolymer consisting of the above component B are mixed to form an isocyanate as the main component of a one-component elastic sealant that can be cured by moisture in the air. Prepare the prepolymer. The content of isocyanate groups contained in the prepolymer after this mixing is usually 0.7
It is about 5.5% by weight.

The mixing ratio of the polyoxyfulkylene prepolymer and the acrylic prepolymer is 10 to 80% by weight, preferably 10 to 60% by weight, and 90 to 20% by weight,
The content is preferably 90 to 40% by weight. If the polyoxyalkylene prepolymer exceeds 80% by weight, the weather resistance of the cured sealant will deteriorate; if it is less than 10% by weight, it will be difficult to reduce the viscosity of the sealant, impairing installation workability, or causing the sealant to harden. Both are inappropriate because the elongation of the object becomes small.

In addition, when mixing both of the above prepolymers,
,.

Considering the compatibility of both prepolymers and the curing reactivity due to moisture, for example, depending on the performance of each prepolymer, the mixing ratio may be set to an optimal value within the above range, or the mixture ratio may be set to an optimal value within the above range. It is desirable to take precautions such as using the same type of organic diisocyanate compound.

The reaction promoting catalyst used in this invention is a catalyst for promoting the reaction between the free isocyanate groups in the prepolymer and moisture in the air, and any of the various catalysts commonly used in urethanization reactions can be used. can. Preferred specific examples thereof include organometallic compounds such as dibutyltin dilaurate, tin octylate, lead octylate, monobutyltin oxide, dioctyltin dilaurate, manganese octylate, N-N-dimethylcyclohexylamine, tri-n-butylamine, and tri-n-butylamine. Ethylenediamine, N
-N-dimethylbenzylamine, amine compounds such as 1,8-diazabicyclo[5,4,6]undecene-7, and salts thereof.

These reaction promoting catalysts are used in an amount of 0.005 to 10 parts by weight, preferably 0.0 parts by weight, based on 100 parts by weight of the above prepolymer.
It is preferable to add it in a proportion of 1 to 5 parts by weight. If the amount of the catalyst used is less than 0.005 parts by weight, the effect of promoting the above reaction will not be sufficient. This reaction-promoting effect increases as the amount used increases, but it is almost saturated at about 10 parts by weight, and even if more than 9 parts by weight of the catalyst is added, hardly any increase in the reaction-promoting effect is observed.

The filler used in this invention is one that improves the strength of the one-component elastic sealant of this invention and improves workability by making the viscosity of the sealant appropriate, and includes, for example, calcium carbonate, silica powder, and talc. , glass powder, magnesia, clay powder, titanium oxide, etc. are preferably used.

The addition ratio should be 30 to 250 parts by weight, preferably 50 to 150 parts by weight, based on 100 parts by weight of the prepolymer (if it is less than 30 parts by weight, it will be difficult to obtain a product with the desired strength; If it exceeds 250 parts by weight, the elongation rate of the cured product will be low, making it difficult to obtain preferable elastic properties.

In addition, when blending these fillers, it is preferable to dehydrate in advance by heating under reduced pressure or the like to reduce the water content to 0.1% by weight or less.

The one-component elastic sealant of the present invention is produced by sufficiently mixing a prepolymer, a reaction accelerating catalyst, and a filler in a predetermined proportion in a conventional mixer, and, if necessary, adding pigments such as those used in general sealants. Thixotropic agents, anti-aging agents, anti-mold agents, antioxidants, ultraviolet absorbers, plasticizers, anti-ozonants,
It is obtained by mixing a tackifier, a surfactant, etc. in an amount of 6, and finally dehydrating the entire mixture.

The dehydration treatment can be carried out using a normal dehydration treatment method, such as a reduced pressure heating method (in this case, it is generally desirable to keep the water content of the blended system at 0.05% by weight or less; If there is a large amount of water, the water will react with the isocyanate groups in the prepolymer before the sealant is applied, increasing the viscosity, resulting in poor workability or, in the worst case, hardening.

In special cases, dehydration treatment can also be carried out using hygroscopic or desiccant agents such as zeolite or silica gel; in this case, these additives that have absorbed water in the system must be intentionally removed from the formulation. (However, the storage stability of the sealant can be improved.)

〔Effect of the invention〕

As is clear from the above explanation, in this invention,
By using an isocyanate prepolymer made of a mixture of a specific polyoxyalkylene prepolymer consisting of the A component and a specific acrylic prepolymer consisting of the B component as the main component of the one-component elastic sealant, an acrylic sealant can be obtained. Excellent weather resistance, durability,
In addition to having heat resistance, it is easy to adjust the viscosity of the sealant and the physical properties of the cured sealant.
By using an acrylic isocyanate prepolymer made from a low-molecular-weight acrylic copolymer that has a specific number of functional groups that can react with isocyanate groups at the molecular ends and arbitrary positions within the molecule, low modulus and high In addition to being able to stretch and satisfy the properties required for architectural sealants, it also avoids concerns about the surface of the cured sealant becoming sticky and reducing contamination properties. .

〔Example〕

Examples of this invention will be described below. In addition, in the following, "part" means part by weight, "%" means weight %, and "molecular weight" means number average molecular weight.

Example 1 100 parts of n-butyl acrylate, 5 parts of acrylic acid, and 2 parts of 2-mercaptoacetic acid were mixed, and 30% of the mixture was placed in a four-bottle flask and heated to 60° C. with stirring while passing nitrogen through the mixture. After the inside of the flask was purged with nitrogen for about 60 minutes, 0.1 part of α·α'-azobisisobutyronitrile was added, and heat generation immediately started. After the heat generation became mild, 0.2 part of α·α'-azobisisobutyronitrile was added to the remainder of the above composition and was gradually dropped into the flask using a dropping funnel. The dropping time was approximately 3 hours, and the polymerization was terminated when no heat generation was observed thereafter.

The acrylic low molecular weight copolymer thus obtained had a polymerization rate of 99.5% and a viscosity of 9.0 as measured by a B-type rotational viscometer.
The molecular weight determined by vapor pressure osmosis at 30° C. (30° C., 2 rpm) was 5,000. The number of functional groups capable of reacting with isocyanate groups per molecule was 4.22.

After 100 parts of this low molecular weight copolymer was sufficiently dehydrated by heating under reduced pressure, 0.001 part of dibutyltin dilaurate was added and thoroughly stirred, and then 15.5 parts of 2,4-tolylene diisocyanate was added and stirred. while heating to 70°C. The reaction was completed in about 5 hours and the acrylic prepolymer (
An isocyanate group content of 3.09%) was obtained.

On the other hand, after dehydrating 100 parts of polypropylene glycol with a molecular weight of 5.000 as determined by the end group determination method, 0.001 part of dibutyltin dilaurate was added thereto and thoroughly stirred, and then 2,4-tolylene diisocyanate 7
．． 3 parts were added and heated to 60° C. with stirring. The reaction was completed in about 5 hours, and a polyoxyalkylene prepolymer (isocyanate group content: 1.60%) was obtained.

Mix 30 parts of the above acrylic prepolymer and 70 parts of polyoxyalkylene prepolymer, add 70 parts of calcium carbonate, 30 parts of titanium dioxide, and 0.5 parts of antioxidant (trade name Irganox 1010, manufactured by Ciba Geigy).
1 part and 1-0.1 part of dibutyl tin dilaure. This blended composition is premixed using a kneader, then kneaded using three rolls, then heated under reduced pressure using a kneader, and dehydrated until the water content in the blended composition becomes 0.01%. A liquid type elastic sealant was obtained.

- Example 2 An acrylic low molecular weight copolymer was obtained in the same manner as in Example 1 using 100 parts of 2-ethylhexyl acrylate, 3.0 parts of 2-hydroxyethyl acrylate, and 1 part of 2-aminoethanethiol. . This copolymer has a polymerization rate of 99
．． 4%, viscosity measured by B-type rotational viscometer is 300 boids (3
(0℃, 2 rpm), the molecular weight by vapor pressure osmosis is s, o
oo, the number of functional groups capable of reacting with isocyanate groups per molecule was 3.01.

After thoroughly dehydrating 100 parts of this low molecular weight copolymer by heating under reduced pressure, it was added with 0 parts of dibutyltin dilaurate.
．． 001 parts of 4,4'-diphenylmethane diisocyanate were added and stirred thoroughly, and then 9.82 parts of 4,4'-diphenylmethane diisocyanate were added and heated to 65°C while stirring.

The reaction was completed in about 4 hours, and an acrylic prepolymer (isocyanate group content: 1.43%) was obtained.

On the other hand, after dehydrating 100 parts of polypropylene glycol with a molecular weight of 3.000 as determined by the end group determination method, 17.
5 parts were reacted in the same manner as in Example 1 to form a polyoxyalkylene prepolymer (isocyanate group content: 2
．． 50%).

Mix 80 parts of the above acrylic prepolymer and 20 parts of polyoxyalkylene prepolymer, add 150 parts of calcium carbonate, 20 parts of titanium dioxide, and antioxidant (
Same as in Example 1) 2 parts, dibutyltin dilaurate 0.01 part and carpo t-noblack 0.2 parts
A one-component elastic sealant of the present invention was obtained by blending the following parts and kneading and dehydrating them in the same manner as in Example 1.

Example 3 Acrylic low molecular weight copolymer was prepared in the same manner as in Example 1 using 80 parts of n-butyl acrylate, 20 parts of n-butyl methacrylate, 3.5 parts of methacrylic acid and 1 part of 2-mercaptoethanol. Obtained union. This copolymer has a polymerization rate of 99.
3%, the viscosity measured by a B-type rotational viscometer is 350 boids (30
℃, 2 rpm), molecular weight by vapor pressure osmosis method is 8.20.
The number of functional groups capable of reacting with isocyanate groups per 0.1 molecule was 4.18.

After 100 parts of this low molecular weight copolymer was sufficiently dehydrated by heating under reduced pressure, 0.005 part of dibutyltin dilaurate was added and thoroughly stirred, and then 10.9 parts of 1,3-bisisocyanatomethylcyclohexane was added and stirred. The mixture was heated to 70°C. The reaction was completed in about 5 hours, and an acrylic prepolymer (isocyanate group content: 3.1%) was obtained.

On the other hand, after dehydrating 100 parts of polypropylene glycol with a molecular weight of 4,000 determined by the end group determination method, 1,3-bisisocyanatemethylcyclohexane was added to
1.7 parts were reacted in the same manner as in Example 1 to obtain a polyoxyalkylene prepolymer (isocyanate base t: 2.27%).

Mix 60 parts of the above acrylic prepolymer and 40 parts of polyoxyalkyne prepolymer, add 70 parts of calcium carbonate, 30 parts of titanium dioxide, and 0.5 parts of antioxidant (same as in Example 1). 1 part and 0.1 part of dibutyltin dilaurate were mixed and kneaded and dehydrated in the same manner as in Example 1 to obtain a one-component elastic sealant of the present invention.

When the characteristics of the one-component elastic sealants obtained in Examples 1 to 3 were evaluated based on JIS-A-5758, the slump of all the sealants was O, 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 one-component elastic sealants of Examples 1 to 3 were subjected to an outdoor exposure test (for 6 months), no surface cracks were found in any of them.

Claims (1)

[Claims] (1) A) An organic diisocyanate compound is added to a polyoxyalkylene polyol having a number average molecular weight of 400 or more so that the amount of isocyanate group is 1 per equivalent of hydroxyl group in the polyol.
．． 10 to 80% by weight of a polyoxyalkylene prepolymer obtained by reacting at a ratio of 8 to 2.3 equivalents,
B) a) an unsaturated monomer having a functional group that can react with an isocyanate group, and b) the following general formula; represents an alkyl group having 2 to 14 carbon atoms) in the presence of c) a polymerization initiator and/or chain transfer agent having a functional group capable of reacting with an isocyanate group, An organic diisocyanate is added to an acrylic low molecular weight copolymer that has an average of about 1 functional group at the end of the molecule and 1.6 to 4.0 functional groups at any position within the molecule that can react with the isocyanate group obtained by copolymerization. 90 to 20% by weight of an acrylic prepolymer obtained by reacting a compound at a ratio of 1.8 to 2.3 equivalents of isocyanate groups per equivalent of functional groups capable of reacting with isocyanate groups in the copolymer. 0.005 to 10 parts by weight of a reaction promoting catalyst and 30 parts by weight of a filler to 100 parts by weight of an isocyanate prepolymer consisting of
A one-component elastic sealant prepared by blending the blend with ~250 parts by weight and dehydrating the blend.