JPS598375B2 - Primer composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a primer composition, and particularly to a primer composition for use as a primer when filling joints of concrete, wood, metal, plastic, etc. with a urethane elastic sealant to improve the adhesion of the sealant. The present invention relates to suitable compositions.

Such primer compositions are required to have good adhesion, and for those used outdoors such as in buildings, there is little deterioration over time in terms of heat resistance, weather resistance, durability, etc. It is desired that the function can be maintained for a long period of time. As a primer composition conventionally used for this type of purpose, a urethane-based prepolymer obtained by an addition reaction between an isocyanate compound and a polyol such as polyethylene glycol is known.

However, although this prepolymer is satisfactory in terms of adhesion to some extent, it cannot necessarily be fully satisfied in terms of properties such as heat resistance, weather resistance, and durability, and its properties deteriorate over time under harsh conditions. In some cases, it was inferior, and improvements were desired. The present invention aims to provide a new type of primer composition that is completely different from such conventional urethane-based primers, and its gist is that (a)
) an unsaturated monomer having a functional group capable of reacting with an isocyanate group; and (b) a general formula R, CH2-C-C00R2 (where R7 is hydrogen or a methyl group, and R2 is an alkyl group having 1 to 14 carbon atoms); Indicates the group.

) with an average of 2 to 10 of the above functional groups in one molecule obtained by copolymerizing the unsaturated monomer represented by A low molecular weight acrylic copolymer containing a free isocyanate group is obtained by reacting an organic diisocyanate in an amount equivalent to about twice the functional group in the low molecular weight acrylic copolymer. The purpose is to use an acrylic isocyanate prepolymer. The acrylic isocyanate prepolymer used in the present invention is synthesized by the method described above, preferably has a molecular weight usually in the range of 1,000 to 50,000, and is generally dissolved or dissolved in an organic solvent. Use as a primer in a dispersed state.

Since such an acrylic isocyanate prepolymer has a free isocyanate group in its molecule, it reacts with moisture in the air after application, and increases its molecular weight in linear and network forms to form a film.

This coating is essentially different from existing urethane-based coatings, and not only has good weather resistance, durability, and heat resistance as a polyacrylic coating, but also has good resistance to various adherends. It has been found that when a commercially available urethane sealant is applied on the above coating, it increases the adhesive force between the sealant and the adherend, and also has good results over time. Ivy. The acrylic low molecular weight copolymer used to obtain the acrylic incyanate prepolymer in this invention is an unsaturated monomer (hereinafter referred to as component a monomer) having a functional group that can react with an isocyanate group. ) and the general formula (where R1 represents hydrogen or a methyl group, and R2 represents an alkyl group having 1 to 14 carbon atoms.

) (hereinafter referred to as component b monomer) in the presence of a conventional polymerization initiator and chain transfer agent. It is important that one molecule contains on average 2 to 10 functional groups that can react with the isocyanate groups introduced by the component monomers. Average of 2 to 1 molecule
If the acrylic low molecular weight copolymer has 10 functional groups, the low molecular weight acrylic copolymer has a molecular weight distribution, and the number of functional groups in the low molecular weight copolymer is O, 1, 2, etc.・・・・・・
...It may be n pieces, but it means that 2 to 10 functional groups are included relative to the average molecular weight.

If the number of these functional groups is less than 2, the strength of the coating will be weak or the adhesive function will be poor, and if it is more than 10, gelation may occur during reaction with the isocyanate compound or the final primer obtained. Both methods are unsuitable because the resulting film is hard and brittle. The a component monomer 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 acrylic acid, methacrylic acid, etc. acid, 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, polyethylene glycol acrylate (
methacrylate), polypropylene glycol acrylate (methacrylate), N-methylol acrylamide, N-methylol methacrylamide, N-methylaminoethyl acrylate, N-methylaminoethyl methacrylate, N-Tert-butylaminoethyl acrylate, N-Tert-butylamino Examples include ethyl methacrylate, 2-hydroxypropyl acrylate, and 2-hydroxypropyl methacrylate.

These a-component monomers are preferably used at a molar ratio of 1/5 to 1/500 with respect to the b-component monomer described below, and within this range, the polymerizability ratio of itself and It is determined that an average of 2 to 10 functional groups are introduced into the copolymer molecule, taking into account the degree of polymerization determined by the amounts of the polymerization initiator and chain transfer agent used. The component b monomer to be copolymerized with the component a monomer has the general formula (wherein R1 represents hydrogen or a methyl group, and R2 represents an alkyl group having 1 to 14 carbon atoms.

) 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 methyl, ethyl, n-butyl, isobutyl, 1-ethylpropyl, 1-methylpentyl, 2-
Examples include methylpentyl, 3-methylpentyl, 1-ethylbutyl, 2-ethylbutyl, isooctyl, 2-ethylhexyl, 3,5,5-trimethylhexyl, decyl, and dodecyl.

If an alkyl group having more than 14 carbon atoms is used, problems arise in adhesiveness to sealants and adherends (concrete, wood, etc.). In the present invention, up to about half of the b-component monomers can be replaced with other copolymerizable unsaturated monomers.

Specific examples of copolymerizable unsaturated monomers include vinylpyridine, vinyl ethers, acrylonitrile, methacrylonitrile, methyleneglutaronitrile, N-N-dimethylaminoethyl acrylate, vinyl halides,
Butadiene, chloropyrene, styrene, acrylic acid amide, vinylpyrrolidone, cyclohexyl acrylate,
Glycidyl acrylate, β-ethoxy acrylate,
Vinyl acetate. Examples include sulfoacrylate, mono(2-hydroxyethyl-α-chloroacrylate) acid phosphate, and the like. The type and usage ratio of these unsaturated monomers may be appropriately determined depending on the purpose of use of the primer, but if the ratio of the unsaturated monomers in the total amount of the b component monomer is more than half, the above-mentioned unsaturated monomers as an acrylic brimer Characteristics may be impaired. Polymerization initiators used in this invention include benzoyl peroxide, lauroyl peroxide, methyl ethyl ketone peroxide,
Known polymerization initiators such as azobisisobutyronitrile and azopisvaleronitrile can be used, and are usually used in an amount of 0.01 to 2 parts by weight based on 100 parts by weight of component b monomer.

In addition, the chain transfer agent may be any compound having a large ability to transfer polymer chains during polymerization, and specific examples include carbon tetrachloride, carbon tetrabromide, n-butyl mercaptan, lauryl mercaptan, etc. be able to.

These chain transfer agents are generally used in an amount of 0.3 to 25 parts by weight per 100 parts by weight of the component b monomer. 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 polymerization, or only a portion may be charged at first, and the remaining portion may be gradually added by a dropwise method as the polymerization reaction progresses. It is preferable to add the mixture after the inner bath containing the mixture of polymer 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.

In this polymerization reaction, the use of a chain transfer agent makes it easy to control the polymerization with regard to heat generation and viscosity increase, and the bulk polymerization method that does not use a solvent may be adopted, or the solution polymerization method that uses a solvent as a medium may be used. It may be done by adopting

In the latter method, a solvent such as n-heptane, toluene, benzene, n-hexane, dioxane, methyl ethyl ketone, methyl isobutyl ketone, or ethyl acetate 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.

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 generation occurs. The organic diisocyanate to be reacted with the acrylic low molecular weight copolymer having a functional group polymerized as described above has two free isocyanate groups at any position within the molecule, for example, 4,4'-diphenylmethane diisocyanate. , 3,3'-dimethyl-4,4-diphenylmethane diisocyanate, 4,4'-cyclohexylmethane diisocyanate, toluylene diisocyanate, hexamethylene diisocyanate, xylene diisocyanate, p-phenylene diisocyanate, m-phenylene diisocyanate, 4. Examples include 45-isopropylidene dicyclohexyl isocyanate, and these are used alone or in combination of two or more.

The amount of the organic diisocyanate used is approximately twice the equivalent of the functional group of the low molecular weight acrylic copolymer. The equivalent ratio of the functional groups in the acrylic low molecular weight copolymer to the isocyanate groups in the organic diisocyanate is approximately 1:
2, free isocyanate groups remain in the molecule of the acrylic isocyanate prepolymer product. The reaction between an acrylic low molecular weight copolymer and an organic diisocyanate can be carried out according to a conventional method. For example, a predetermined proportion of an organic diisocyanate is charged into a reactor together with a solvent, and a predetermined proportion of an acrylic low molecular weight copolymer is added to a reactor. If the viscosity of the above-mentioned copolymer is high, the combination may be carried out by diluting it with an appropriate solvent and dropping it dropwise with stirring.

Examples of the solvent used here include toluene, benzene, methyl ethyl ketone, and ethyl acetate. The reaction temperature and reaction time vary depending on the type of functional group, the type of organic diisocyanate, and the type of solvent, but usually the reaction may be carried out at a temperature in the range of room temperature to 150°C for several hours to several tens of hours.

Further, a reaction promoting catalyst can also be used to lower the reaction temperature and shorten the reaction time.

Specific examples thereof include organometallic compounds such as dibutyltin dilaurate, tin octylate, lead octylate, monobutyl toxide, dioctyltin dilaurate, manganese octylate, N-N-dimethylcyclohexylamine, tri-n-butylamine, and tri-n-butylamine. ethylenediamine,
Examples include amine compounds such as N-N-dimethylbenzylamine and 1,8-diazabicyclo[5,4,6]undecene-7, and salts thereof. These reaction promoting catalysts are preferably added in a proportion of 0.01 to 5 parts by weight per 100 parts by weight of the low molecular weight acrylic copolymer. The above-mentioned reaction promoting catalyst also functions as a reaction promoting catalyst when the acrylic isocyanate prepolymer forms a film by reacting with moisture in the air. The acrylic isocyanate prepolymer synthesized in this way is usually in the state of a solution with a solid content of 5 to 60% by weight, depending on the organic solvent added during or after the synthesis, and in some cases the same as above. It is used as a primer in the form of a dispersion having a solid content of .

The above solid content content is determined from the viewpoint of adhesion and workability required for the primer, as well as from the viewpoint of price.If the solid content content is too low, sufficient adhesion cannot be obtained; conversely, if it is too high, If it is too high, the viscosity may increase, which may impair workability or increase costs. In addition to the prepolymer and solvent or dispersion medium as described above, the primer composition of the present invention may contain optional components depending on the purpose of use, if necessary, to the extent that the original purpose is not impaired. can.

These optional components include the reaction accelerating catalyst described above and conventionally known pigments, anti-aging agents, plasticizers, tackifiers and the like. When applying the primer composition of the present invention to, for example, joints in buildings, it is generally sufficient to apply it to the surface of the adherend by means such as spraying or brushing.

When air-dried after this application, the prepolymer increases in molecular weight in the form of lines and networks due to the moisture in the air, forming a film with excellent properties such as adhesion, weather resistance, heat resistance, and durability.
Therefore, by further applying a urethane sealant or the like after forming the above-mentioned film, the adhesion of this sealant to the adherend can be greatly improved and its deterioration over time can be suppressed.

Next, the present invention will be explained in more detail with reference to Examples.
Note that in the following, parts and % mean parts by weight and % by weight, respectively. Example 1 100 parts of n-butyl acrylate, 3.7 parts of 2-hydroxyethyl acrylate and 1 part of n-butyl mercaptan
．． 5 parts of the mixture was mixed, and 30% of this mixture was placed in a 300CC four-bottle flask and heated for 70 minutes under stirring while flowing nitrogen.
Warmed to ℃.

After purging the inside of the flask with nitrogen for about 50 minutes, 0.1 part of α・α″-azobisisobutyronitrile was added. After the heat generation became a little hidden, α・α″ was added to the remaining 70% of the mixture.
A mixture containing 0.2 part of α1-azobisisobutyronitrile was gradually dropped into the flask using a dropping funnel. 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 obtained in this way has a polymerization rate (weighed after heating and drying at 150°C for 30 minutes) of 99.3% and an average molecular weight (by vapor pressure osmosis method) of 1900001 and the number of hydroxyl groups per molecule. (
(calculated from the acetyl value and molecular weight) was 2.6. 50 parts of toluene was added to 100 parts of the thus obtained copolymer and heated to perform azeotropic dehydration. Next, the above copolymer solution was added dropwise to another 300CC four-bottle flask containing 5.5 parts of toluylene diisocyanate and 0.5 parts of dibutyltin dilaurate, and the reaction was carried out at 85°C for 4 hours. Then 100 parts of ethyl acetate was added to prepare the primer composition of the present invention. The isocyanate content of the composition thus obtained (determined by dibutylamine 1
amount) was 0.57%. Example 2 100 parts of butyl acrylate, 30 parts of acrylonitrile,
6.9 parts of Nt-butylaminoethyl methacrylate,
A mixture consisting of 1.8 parts of lauryl mercaptan is prepared.

50 parts of benzene and 30 parts of the above mixture were placed in a 300 CC four-hole flask, and the inside of the flask was purged with nitrogen while stirring, and the inner bath was heated to 70°C. After purging with nitrogen for about 60 minutes, 0.1 part of α·α7-azobisisobutyronitrile was added. After the heat generation due to double polymerization became a little hidden, a mixture obtained by adding 0.2 part of α・α″-azobisisobutyronitrile to the remainder of the mixture was gradually added using a dropping funnel.
It was added slowly into the flask.

The dropping time was 2 hours, and the polymerization was terminated when no heat generation was observed. The acrylic low molecular weight copolymer thus obtained had a polymerization rate of 98.8% and an average molecular weight of 1,100,001, and the number of amino groups per molecule (measured by molecular weight and microkjeldahl method) of 5.3. .

After heating and dehydrating this copolymer solution, 4.4/-
9.7 parts of diphenylmethane diisocyanate and 0.05 part of tin octylate were added and reacted at 80°C for 6 hours. After this reaction, 0.5 part of Irganox 1010 (antiaging agent manufactured by Ciba Kirkey) and ethyl acetate were added. 400 parts were added to form the primer composition of the present invention.

The isocyanate content (as determined by dibutylamine) of this composition was 0.3%. Examples 3 to 6 4 was prepared in the same manner as in Examples 1 and 2 using the component ratios shown in Table 1 below.
A seed acrylic low molecular weight copolymer was obtained.

The polymerization rate, average molecular weight, and number of functional groups per molecule of each copolymer are as shown in the same table. Each of the above acrylic low molecular weight copolymers was dehydrated in the same manner as in Examples 1 and 2, and 100 parts of each of the dehydrated acrylic low molecular weight copolymers and the organic An acrylic isocyanate prepolymer was obtained by reacting the diisocyanate with the catalyst shown in the same table under each reaction condition shown in the same table.

The organic solvents shown in the table were added to the prepolymers thus obtained to obtain four types of primer compositions. The isocyanate content of each composition is shown in the same table. Comparative Examples 1-2 In the same manner as in Examples 1 and 2 using the component ratios shown in Table 3 below, 2
A seed acrylic low molecular weight copolymer was obtained.

The polymerization rate, average molecular weight, and number of functional groups per molecule of each copolymer are as shown in the same table. Each of the above acrylic low molecular weight copolymers was dehydrated in the same manner as in Examples 1 and 2, and 100 parts of each acrylic copolymer after the dehydration treatment was combined with the organic The diisocyanate was reacted with the catalyst shown in the same table under each reaction condition shown in the same table. Through this reaction, the required acrylic isocyanate prepolymer was obtained in Comparative Example 1, but in Comparative Example 2, the prepolymer could not be obtained due to gelation during the reaction.

Regarding Prepolymer 1 of Comparative Example 1, 50 parts of toluene and 70 parts of ethyl acetate were further added as organic solvents to prepare Primer 21 composition. The isocyanate content in this composition was 0.58%. Next, the following tests were conducted to investigate the characteristics of each primer composition of Examples 1 to 6 and Comparative Example 1 described above.

Test-1> Each composition was applied with a brush to the surface of mortar prepared according to JISR52Ol, and the mixture was heated at 20°C and 60% relative humidity for 30 minutes.
Dry for minutes to form a film, and apply JISA5757
Commercially available urethane-based 3-component elastic sealant (
Samples for adhesion tests were prepared by applying Nito Seal A-2000 (trade name, manufactured by Nitto Electric Industry Co., Ltd.), and these samples were tested for tensile strength (Tmax), elongation (E), and failure state.

The results were as shown in Table 5 below. For reference, test results in the case where no primer composition was applied are also listed in the same table as a reference example. Test 1> Using the samples of Examples 1 to 6 prepared in Test-1, tensile test after being left at 80°C for 14 days (heat resistance test), tensile test after being immersed in 50°C hot water for 7 days test(
A tensile test (durability test) after a first class concrete durability test according to JISA5757 was conducted.

The results were as shown in Table 6 below. Test 1> For the primer composition of Example 3, fine sealer No. 1 #200 (7V) manufactured by Japan Additive Industry Co., Ltd. was used as a urethane-based elastic sealant. 1), Showa Sekiyu Asu 2. Uset (Fu 2) manufactured by Falto, Takenate L manufactured by Takeda Pharmaceutical Co., Ltd.
-3001 (7f63) and Nippon Polyurethane Industries Co., Ltd. U-Lite (/F64) 4 types ★ or more tests -11,
As is clear from the above, the primer composition of the present invention has an excellent adhesion function as a primer, and also has excellent heat resistance and
Samples for adhesion tests were prepared in the same manner as in Test-1 using a weather-resistant sealant, and the bowing adhesive strength, elongation, and failure state of each sample were examined by a tensile test.

Claims (1)

[Claims] 1 (a) An unsaturated monomer having a functional group that can react with an isocyanate group; (b) General formula ▲ Numerical formula, chemical formula, table, etc. ▼ (However, R_1 is hydrogen or a methyl group. , R_2 represents an alkyl group having 1 to 14 carbon atoms. ) and, if necessary, other unsaturated monomers that can be copolymerized with the above monomers. An acrylic low molecular weight copolymer having an average of 2 to 10 of the above-mentioned functional groups in one molecule obtained by the above-mentioned method is added with an organic diisocyanate in an amount of about twice the equivalent of the functional groups in this acrylic low molecular weight copolymer. A primer composition whose main component is an acrylic isocyanate prepolymer having free isocyanate groups in the molecule obtained by reacting the acrylic isocyanate prepolymer.