JPS6076589A - Elastic sealant of one-pack type - Google Patents

Abstract

PURPOSE:An elastic sealant one-pack type curable with water in air, comprising a mixture of a liberated isocyanate group-containing acrylic prepolymer and polyoxyalkylene prepolymer as a main component. CONSTITUTION:(A) 30-80wt% (i) an unsaturated monomer [e.g., (meth)acrylic acid, etc.] containing a functional group capable of reacting with an isocyanate group and (ii) an unsaturated monomer shown by the formula (R1 is H, or methyl; R2 is 2-14C alkyl) is blended with (B) 70-20wt% polyoxyalkylene polyol, the blend is reacted with (C) 1.8-2.3 equivalent organic diisocyanate compound based on the functional group of the component i, to give an isocyanate group-containing prepolymer. 100pts.wt. of the prepolymer is blended with 0.1-10pts.wt. catalyst for promoting a reaction and 30-200pts.wt. filler and dehydrated to give the desired sealant.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention comprises as a main component a mixture of an acrylic prepolymer having free incyanate groups in the molecular pile and a polyoxyalkylene prepolymer having free incyanate groups in the molecule, This invention relates to a one-component elastic sealant that can be cured by moisture in the air.

Sealants filled into the joints of buildings 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. It is desirable that the material does not contain substances that can be dispersed into the atmosphere, such as water or organic solvents, which can cause weight loss.

Conventionally, fillers have been made mainly of prepolymers having isocyanate groups at the molecular ends obtained by reacting polyoxyalkylene polyols with organic diisonoanates.
One-component urethane sealants containing softeners and other ingredients that harden due to moisture in the air are known, but these conventional urethane sealants have problems with weather resistance and cannot be exposed outdoors for long periods of time. However, there was a drawback that cracks formed on the surface of the sealant.

On the other hand, polyacrylic sealants have the advantage of being excellent in weather resistance, durability, and heat resistance, but because of their high viscosity, they are usually non-crosslinked, non-elastic emulsion type or organic solvent type sealants. When this type of sealant is filled into joints, it cannot follow changes in the joint over time due to thermal effects, causing cracks and gaps to grow, and water, organic solvents, etc. to be released into the atmosphere. As a result, the sealant often loses its appearance over time after filling, and does not function satisfactorily as a sealant.

In contrast, solvent-free, cross-linked polyacrylic sealants have recently become known. For example, there may be mentioned a sealant whose main component is an acrylic prepolymer having one free incyanate group in the molecule, which is obtained by introducing an incyanate group into a low molecular weight acrylic copolymer. This type of sealant has excellent weather resistance, colorability, durability, heat resistance, etc., and has excellent elasticity.
There is no problem as mentioned above because it does not contain any substances scattered into the atmosphere.

However, in this type of sealant, the functional groups that contribute to crosslinking in the acrylic prepolymer are located at arbitrary positions, making it difficult to adjust the viscosity of the sealant and the physical properties of the cured sealant, especially modulus and elongation. There is a drawback. For example, in order to make the cured sealant material have low modulus and high elongation, it is necessary to increase the molecular weight of the acrylic prepolymer, but this tends to increase the viscosity of the sealant and reduce workability. On the other hand, when trying to improve workability, the physical properties of the cured sealant tend to deteriorate.

The inventors have developed various elastic sealants with the aim of obtaining elastic sealants that do not have the above-mentioned drawbacks, have sufficient elastic properties, especially low modulus, for filling joints in buildings, etc., and also have excellent weather resistance. As a result of this study, we have come up with this invention.

That is, this invention provides a) an unsaturated monomer having a functional group that reacts with an incyanate group, and b) a general formula % (where R represents hydrogen or a methyl group, and R2 represents a carbon number of 2). An acrylic low molecular weight copolymer obtained by copolymerizing an unsaturated monomer represented by 1 to 14 alkyl groups) and a polyoxyalkylene monomer, or the above component a monomer and the above b. Acrylic low molecular weight copolymers obtained by copolymerizing component monomers in the presence of polyoxyalkylene polyols, graft products of acrylic low molecular weight copolymers and polyoxyalkylene polyols, and polyoxyalkylene polyols. (hereinafter referred to as B mixture), in which the total amount of the a component monomer and the b component monomer is 30 to 80% by weight, and the polyoxyalkylene polyol is 70 to 20% by weight. The organic diincyanate compound is added to the mixture in which the organic diincyanate compound is used in the proportions corresponding to the functional groups capable of reacting with the incyanate groups including the hydroxyl groups of the polyoxyalkylene polyol in the mixture. Isocyanate group is 1.8-2
100 parts by weight of the incyanate group-containing prepolymer obtained by reacting at a ratio of 3 times the equivalent, and 0 parts of the reaction accelerating catalyst.
A liquid type one-component elastic sealant of the present invention is obtained by blending 1 to 10 parts by weight of a filler and 30 to 200 parts by weight of a filler, and dehydrating the mixture. Because the main component is a prepolymer containing a specific proportion of Since the physical properties of the sealant cured product can be easily adjusted, the workability during construction is excellent, and the cured product has the characteristics of low modulus and high elongation.

Either may be used. To obtain the above mixture A,
An acrylic low molecular weight copolymer produced as described below and a polyoxyalkylene polyol may be mixed. In order to obtain mixture B, the acrylic low molecular weight copolymer is polymerized in the presence of a polyoxyalkylene polyol.

In either case, the total amount of the a component monomer and the b component monomer used in the polymerization of the acrylic low molecular weight copolymer is 30 to
80% by weight, polyoxyalkylene polyol from 70%
It is used in a proportion of 20% by weight.

In the above mixture B, since the low molecular weight acrylic copolymer is grafted onto the polyoxyalkylene polyol or partially contained therein, the compatibility between the low molecular weight acrylic copolymer and the polyoxyalkylene polyol in the mixture is low. It has the advantage of being good.

In addition, in the above-mentioned blending ratio when obtaining these mixtures, if the blending ratio of component a monomer and component b monomer is less than 30% by weight, the weather resistance of the sealant will deteriorate; Exceeding this is not preferable because problems such as the cured sealant having a high modulus and no elongation or the sealant having a high viscosity and poor workability occur.

The acrylic low molecular weight copolymer in A mixture ζ is a
] An unsaturated monomer having a functional group capable of reacting with an incyanate group and b) General formula % Formula % (However, R1 represents hydrogen or a methyl group, and R2 represents an alkyl group having 2 to 14 carbon atoms.) It is produced by copolymerizing an unsaturated monomer represented by 1 in the presence of a conventional polymerization initiator and a chain transfer agent, and 3
It usually has an average of 1.8 to 2.5 functional groups per molecule that reacts with incyanate groups introduced by component monomers, and its weight average molecular weight is usually 1.000 to 20,000.
Those within the range of are preferably used.

Having an average of 1.8 to 25 functional groups in one molecule means
The acrylic low molecular weight copolymer has a molecular weight distribution,
and the number of functional groups in this low molecular weight copolymer is 0.1.2
...There may be n pieces, but 1.
This means that 8 to 2.5 functional groups are included.

If the number of C functional groups is too small, the strength of the cured product will be low, and if it is too large, the elongation rate of the cured product will be low.

Furthermore, if the weight average molecular weight of the above-mentioned low molecular weight acrylic copolymer is too low, the modulus of the cured sealant product will be high and elongation will be low, which is undesirable. If this molecular weight is too high, the viscosity of the sealant will be high and workability will be reduced. This is not preferable because it lowers the temperature.

Regarding the acrylic copolymer of mixture B obtained when the above copolymerization is carried out in the presence of a polyoxyalkylene polyol, and the acrylic copolymer in a graft product of an acrylic copolymer and a polyoxyalkylene polyol. Also, it is preferable that the number of functional groups capable of reacting with the incyanate group introduced by the λ component monomer and the weight average molecular weight are within the above ranges.

The three-component monomer used here may be an unsaturated monomer having a functional group such as a carboxyl group, a hydroxyl group, or an amide group that can react with an incyanate group. Specific examples include acrylic acid , methacrylic acid, 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, Bolier 11-col acrylate (methacrylate), polypropylene glycol acrylate (methacrylate), N-methylaminoethyl acrylate, N-methylaminoethyl methacrylate, 2 −
Examples include hydroxypropyl acrylate and 2-hydroxypropyl methacrylate.

These component a monomers are preferably used in a ratio such that the molar ratio of component I monomers to monomers described below is 115 to 11,500, and within this range, the polymerizability ratio of itself and Considering the degree of polymerization determined by the amount of polymerization initiator and chain transfer agent used, an average of 18 to 25
Determine the number of functional groups to be introduced.

The b component monomer to be copolymerized with the above three component monomers is represented by the general formula % (where R1 represents hydrogen or a methyl group, and R2 represents an alkyl group having 2 to 14 carbon atoms). It is an alkyl ester of acrylic acid or methacrylic acid, and one or more of these are used.

The alkyl group (R2) in the above general formula may be branched or unbranched, and specific examples of this alkyl group include ethyl, n-butyl, isobutyl, 1-ethylpropyl, 1-ethylpropyl, Examples include methylpentyl, 2-methylpentyl, 3-methylpentyl, 1-ethylbutyl, 2-ethylbutyl, inoctyl, 3,5,5-trimethylhexyl, decyl, and dodenyl. 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 this invention, up to about half of the component monomers mentioned above can be replaced with other copolymerizable unsaturated monomers. Specific examples of copolymerizable unsaturated monomers include vinyl pyridine, vinyl ethers, acrylonitrile, methacrylate trile, methyl methacrylate,
N,N-dimethylaminoethyl acrylate, vinyl halide, butadiene, chloroprene, styrene, acrylamide, vinylpyrrolidone, cyclohexyl acrylate, glycidyl acrylate, β-ethoxoacrylate, vinyl acetate, mono-(2-hydroxyethyl -α-chloroacrylate) acid phosphate,
Examples include fluoroalkyl acrylate.

The type and proportion of these unsaturated monomers should be appropriately determined depending on the purpose of use of the elastic sealant. Characteristics may be impaired.

As the polymerization initiator used in this invention, known polymerization initiators such as benzoyl peroxide, lauroyl peroxide, methyl ethyl ketone peroxide, azobisin butyconvex nitrile, and azobisvaleronitrile can be used.
Usually, it is used in a proportion of 0.1 to 2 parts by weight per 100 parts by weight of component b monomer.

YuL--J-^*Ω starvation+l +-1prA Any compound that has a large ability to emit a small amount of water and move through the ligature A chain is sufficient, specifically carbon tetrachloride and carbon tetrabromide. , n-butyl mercaptan, lauryl mercaptan, and the like. These chain transfer agents contain 100% of the b component monomer.
It is usually used in a ratio of 0.1 to 15 parts by weight based on parts by weight, and by changing this amount, the molecular weight of the low molecular weight acrylic copolymer can be changed.

Molecular weight can also be adjusted by changing the amount of polymerization initiator, but if, for example, a large amount of polymerization initiator is used to lower the molecular weight, the heat generated by polymerization increases, making it difficult to perform polymerization operations. cause great difficulties. However, when a chain transfer agent is used, heat generation does not become a problem, and low molecular weight acrylic copolymers can be easily produced.

Copolymerization of the a component monomer and the b component monomer may be carried out according to a conventional method. First, a mixture of the a component monomer, the b component monomer, and a chain transfer agent in a predetermined ratio is prepared. into the polymerization tank. Regarding the charging method, the entire amount may be charged at once from the beginning of the polymerization, or only a portion may be initially charged and the remainder may be gradually added by a dropwise method as the polymerization reaction progresses.

The polymerization initiator is used only after the mixture of monomers and chain transfer agent has reached a predetermined polymerization temperature and the air in the polymerization tank has been sufficiently replaced with an inert gas such as nitrogen. It is good to add it.

In this polymerization reaction, the use of a chain transfer agent facilitates polymerization control, so a solvent as a medium is not required.
In particular, if it is desired to use a solvent, a solvent such as fn-hebutane, toluene, n-hexano, dioxane, methyl ethyl ketone, methyl imbutyl ketone, ethyl acetate, ipropanol, etc. may be used.

The polymerization temperature varies depending on the type of monomer and polymerization initiator, but is generally preferably in the range of about 50 to 90°C. If the polymerization temperature becomes too high and generates too much heat, adjust it appropriately by cooling with water or the like.

The polymerization time mainly depends on the polymerization temperature and the type of monomer. The end point of the reaction is determined so that as little unreacted monomer remains as possible and no gelation occurs, but it is usually convenient to set the end point as the point at which no heat is generated.

The polyoxyalkylene polyol used to obtain the A mixture and the B mixture is obtained by polymerizing a polyhydric alcohol and an alkylene oxide. This polyol has a weight average molecular weight of 400 to 4.0.
00 is preferred.

If this molecular weight is too low, the modulus of the cured sealant will increase, which is undesirable. If it is too high, the viscosity of the 7-lunt will increase, resulting in a decrease in workability, which is undesirable.

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.

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

Mixture A consisting of an acrylic copolymer and a polyoxyalkylene polyol obtained as described above or an acrylic copolymer, a graft product of an acrylic copolymer and a polyoxyalkylene polyol, and a polyoxyalkylene polyol By reacting the mixture B with an organic diincyanate compound, an incyanate group-containing prepolymer, which is the main component of the elastic sealant of the present invention, is obtained.

Examples of the organic diincyanate compounds include 4,4'-diphenylmethane diincyanate, 3,3
'-dimethyl-4-diphenylmethane diisocyanate, 4,4'-cyclohexylmethane diisocyanate, toluylene diisocyanate, hexamethylene diysyanate, xylylene diysyanate, P-phenylene diysyanate, m-phenylene diysyanate, Examples include 4,4'-impropylidene dicyclohexyl isocyanate, and these can be used alone or in combination of two or more.

When using this organic diisocyanate compound, the inocyanate group of this compound is 1,8 to 2,3 with respect to the functional group that can react with the incyanate group containing the hydroxyl group of the polyoxyalkylene polyol in the above mixture.
Preferably, the amount is double equivalent. If the amount used is too small, the cured sealant will have insufficient elasticity, and if it is too large, the modulus will be high, which is not preferable.

The above mixture and organic diisocyanate may be reacted according to a conventional method, and the reaction temperature and reaction time vary depending on the type of functional group and the type of organic diisocyanate, 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 addition, in carrying out the above reaction.

It is desirable to dehydrate the above-mentioned mixture in advance by heating under reduced pressure or the like to reduce the water content to 0.05% by weight or less.

The isocyanate group-containing prepolymer obtained as described above has a free incyanate group in the molecule, so it can be cured by moisture in the air, and is the main component of the one-component elastic sealant of the present invention. used as.

The reaction promoting catalyst used in this invention is a catalyst for promoting the reaction between the free incyanate groups in the prepolymer and moisture in the air, and any of the various catalysts commonly used in urethanization reactions can be used. Can be used. Preferred specific examples include organometallic compounds such as dibutyltin dilaurate, tin octylate, lead octylate, monobutyltin oxide, dioctyltin dilaurate, manganese octylate, N,N-dimethylcyclohexylamine, trilobylamine, and triethylenediamine. , 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 0.1 to 10 parts by weight, preferably 0.2 to 5 parts by weight, based on 100 parts by weight of the prepolymer.
It is preferable to add it in parts by weight.

If the amount of the catalyst used is less than 0.1 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 a larger amount of 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 elastic sealant of this invention and improves workability by making the viscosity of the sealant appropriate, and includes, for example, calcium carbonate, silica powder, talc, and glass powder. ,
Magnesia, clay powder, titanium oxide, etc. are preferably used. The addition ratio is 30 to 200 parts by weight, preferably 50 to 150 parts by weight, per 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, and if it exceeds 200 parts by weight, the elongation rate of the cured product will be low, making it difficult to obtain favorable elastic properties. is difficult.

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 thoroughly 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, anti-aging agent, anti-mold agent, antioxidant, ultraviolet absorber, plasticizer, anti-ozonant,
It can be obtained by adding and mixing a tackifier, etc., and finally dehydrating the entire mixture1. The water content of the system should generally be 0.05% by weight or less.

If the water content exceeds 0-05% by weight,
Before the sealant is applied, this water reacts with the incyanate groups in the prepolymer, and the viscosity decreases.
: There is a risk that the f4 animal bifK Tsunaha Hatakekoro Kochisa tri-sized Ren.

In special cases, dehydration treatment can also be carried out using moisture-absorbing or drying agents such as zeolite or silica gel.
In this case, the storage stability of the sealant can be improved without intentionally removing from the formulation these additives that have absorbed water in the system.

Examples of this invention will be described below. In addition, in the following, "part" means part by weight, "ch" means part by weight, "5 molecular weight" and "weight average molecular weight", respectively.

Example 1 100 parts of n-butyl acrylate, 4.5 parts of 2-hydroxyethyl acrylate and 2 parts of n-butyl mercaptan
30% of this mixture was placed in a fourth 200 cc flask and heated to 70°C under stirring while flowing nitrogen.
It was heated to. After purging the inside of the flask with nitrogen for about 50 minutes, 0.1 part of α·α'-azobisin butyronitrile was added. After this heat generation became a little hidden, the remaining 70 g of the above mixture was mixed with α・α′-azobisisobutyronitrile.
．． Add 2 parts to the flask using a dropping funnel.
It was dripped gradually. The dropping time was 1.5 hours, and the polymerization was terminated when no heat generation was observed thereafter.

The acrylic low molecular weight copolymer thus obtained has a solid content (weighed after heating and drying at 150°C for 30 minutes) of 9.
9.2%, viscosity (by B type viscometer) 108 bois,
Molecular weight [by vapor pressure osmosis method] is 5,800. Number of hydroxyl groups per molecule (calculated from acetyl value and molecular weight) is 1.9.
Met.

Molecules i3. o
40 parts of polypropylene glycol were mixed and heated under reduced pressure to sufficiently dehydrate the mixture, then 0.01 part of dibutyltin dilaurate and 89 parts of 2,4-tolylene diincyanate were added thereto, and the mixture was heated at 80°C for 50 parts with stirring. After a period of reaction, a prepolymer having an incyanate group content of 1.9% (as determined by dibutylamine) was obtained.

To 100 parts of this prepolymer, 76 parts of calcium carbonate, 7 parts of titanium dioxide, and 360 parts of Disparon. 5 parts of QN (manufactured by Kusumoto Kasei Co., Ltd.), 0.5 parts of Irganox 1010 (manufactured by Ciba Geigy), and 0.5 parts of dibutyltin dilaurate.
1 part was added. This blended composition was premixed using a kneader, then kneaded using three rolls, and then heated under reduced pressure using a kneader until the water content in the blended composition reached 0.
A one-component elastic sealant according to the present invention was obtained by dehydrating the product to a concentration of 1%.

Example 2 A blended composition consisting of 50 parts of n-butyl acrylate, 50 parts of ethyl acrylate, 6 parts of 2-hydroxyethyl acrylate, and 58 parts of lauryl mercaptan was prepared.

A fourth flask of 300 CC was charged with 11,150 parts of polypropylene glyco-1 having a molecular weight of 4,000, and 30 parts of the above blended composition was added thereto.

The inside of this flask was replaced with nitrogen while stirring, and the inside of the flask was replaced with nitrogen for 70 minutes.
Warmed to ℃. After purging with nitrogen for about 60 minutes, 0.05 parts of azobisisobutyronitrile was added.

Polymerization begins after about 17 minutes and generates heat, but after this heat generation becomes a little hidden, a mixture prepared by adding 0.15 parts of azobisin butyronitrile to the rest of the above-mentioned blended composition is gradually added using a dropping funnel. added into the flask. The dropping time was 3 hours, and the polymerization was terminated when no heat generation was observed.

The reaction composition thus obtained had a viscosity (measured by a B-type viscometer) of 70 voids.

After 100 parts of this reaction composition was sufficiently dehydrated by heating under reduced pressure, 0.01 part of dibutyltin dilaurate was added thereto.
- 8.7 parts of 4-tolylene diisocyanate was added and reacted at 80° C. for 5 hours with stirring to obtain a prepolymer with an incyanate group content of 1.8% (determined by dibutylamine).

100 parts of calcium carbonate to 100 parts of this prepolymer,
17 parts of titanium dioxide, 20 parts of calcium oxide, 5 parts of Disparon 360ON (mentioned above), 0.2 part of dibutyltin dilaurate, and 0.2 part of Carbo/Black were blended. This blended composition was premixed in a kneader, thoroughly kneaded with three rolls, then put back into the kneader and heated under reduced pressure, and dehydrated until the water content in the blended composition became 0.001 cm.+++11+-+h Loro Δ\ to Hie 4mM button F, -
l-211Lt-bu and I.

When the characteristics of the liquid-type elastic sealant obtained in Example 12 were evaluated based on JIS-A-5758, the slump of all 7-lunts was 01lIII.
There was no contamination. Furthermore, the extrudability and tensile adhesion properties were as shown in the following table.

Furthermore, when an outdoor exposure test (for 6 months) of the cured products was conducted on the one-component elastic/-lunt of Example 1.2, no surface cracks were found in any of them.

Patent Applicant Nitto Electric Industries Co., Ltd. Procedural Amendment 1. Case description Japanese Patent Application No. 58-185743 2 Name of the invention One-component elastic sealant 3 Amendment person III Interview with Tani V Patent applicant k Address 1-1-2 Shimohozumi, Ibaraki City, Osaka Prefecture Name B (
396) Nitto Electric Industry Co., Ltd. Representative Kamigata Sanbe 4, Agent Mail! No. 530 Address 4-9-8 Nishitenma, Kita-ku, Osaka (Third Building Annex) 5. Date of amendment order 7. Contents of amendment A. Specification: (1) Page 7, lines 1-2 and page 7, line 6; the words "urethane-based component" have been corrected to read "polyokine alkylene-based component" respectively.

(2) Page 22, line 9; First, we have corrected "weight average molecular weight" to "number average molecular weight."

Claims (1)

[Scope of Claims] +l) a) An unsaturated monomer having a functional group that reacts with an incyanate group, and a compound having the general formula A mixture consisting of a polyoxyalkylene polyol and an acrylic low molecular weight copolymer obtained by copolymerizing an unsaturated monomer represented by A low molecular weight acrylic copolymer obtained by copolymerizing component b monomer in the presence of a polyoxyalkylene polyol, a graft product of a low molecular weight acrylic copolymer and a polyoxyalkylene polyol, and a polyoxyalkylene polyol A mixture consisting of 30 to 80% by weight of the above-mentioned a. % of the organic diisocyanate compound, and the organic diisocyanate compound is added to the functional group capable of reacting with the incyanate group, including the hydroxyl group, of the polyoxyalkylene polyol in the mixture. 01 to 10 parts by weight of a reaction promoting catalyst and 30 to 200 parts by weight of a filler are added to 100 parts by weight of an incyanate group-containing prepolymer obtained by reacting the isocyanate groups at a ratio of 1.8 to 2.3 times equivalent. A one-component elastic sealant made by dehydrating this compound.