JPH01113469A - Primer - Google Patents

Abstract

PURPOSE:To obtain a primer excellent in adhesion to (aged) concrete, by mixing a specified unsaturated isocyanate with, optionally, a polymerizable monomer, a polymer soluble in this monomer and a curing agent. CONSTITUTION:An unsaturated alcohol (a) obtained from (meth)acrylic acid and a monoepoxy compound (e.g., 2-hydroxypropyl methacrylate) is reacted with a polyisocyanate (e.g., 2,4-tolylene diisocyanate) to obtain an unsaturated isocyanate (A) having a (meth)acryloyl group and an NCO group in the molecule through a urethane bond. 100pts.wt. component A is mixed with, optionally, 5-200 pts.wt. monomer (B) copolymerizable with the (meth)acryloyl group of component A, a polymer soluble in component B, 0.2-5 pts.wt., per 100 pts.wt. in total of components A and B, curing agent which is preferably a redox system containing an organic peroxide (e.g., benzoyl peroxide).

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to the field of civil engineering and construction, and in particular to a primer for maintenance painting of concrete buildings. This invention relates to a primer suitable for concrete painting, which has extremely strong adhesion to surfaces and has practically sufficient adhesion.

Therefore, the purpose of the present invention is to provide a primer that has excellent adhesion to wet concrete or concrete that has deteriorated over time, to prevent deterioration of concrete structures, to establish a reliable coating system, and to improve the aesthetic appearance by coating. It is intended to bring about this.

[Conventional technology]

At present, emulsion-type coatings are mainly used for concrete coatings due to their ease of formulation and application, but they have sufficient adhesion and hardness for practical use, stain resistance, and protection against salt damage. It is no exaggeration to say that there is currently no paint that can maintain these properties, especially when the concrete contains moisture, or even when it is extremely wet.

[Problem that the invention seeks to solve]

Concrete, unlike metal, is a type of porous material.
In reality, there are countless cracks.

Therefore, paints for this purpose are required to have the ability to follow pores and cracks, and if they also need to serve the purpose of preventing salt damage, they must have the ability to prevent the intrusion of chlorine ions, moisture, oxygen, etc. .

Another problem is that the properties of the materials are different between the surface of newly poured concrete and the surface of aged concrete, making it difficult to achieve good paint adhesion, especially when repairing old concrete. There are many things like that.

In this way, the present invention can coat even concrete with pores and cracks with good followability and prevent the intrusion of moisture, oxygen, and other substances, and it also adheres well to old concrete with deteriorated surface that is the target of repair. The aim is to provide a primer with good properties.

[Means and actions for solving the problem] As a result of various studies in order to form a coating film that adheres well to concrete surfaces, especially wet surfaces, and has sufficient durability, the present inventors have discovered the following. What is decisively important is the quality of the primer that impregnates the concrete surface and firmly adheres to the concrete, and the selection of this primer will determine the success or failure of the concrete paint.

Therefore, the present inventors investigated various primer compositions to obtain reliable adhesion, and found that a primer composition consisting mainly of unsaturated isocyanate having a (meth)acryloyl group and an isocyanate group via a urethane bond. It has been found that a primer and, optionally, a polymerizable monomer, a polymer soluble in the polymerizable monomer, and a curing agent are suitable for these purposes.

By applying these primers to the concrete surface and impregnating them, and simultaneously bonding the isocyanate groups and concrete components and polymerizing the unsaturated groups for 4 minutes, it was possible to obtain a coating film that adhered extremely strongly to the concrete. With this finding, we were able to complete the present invention.

The unsaturated isocyanate compound used in the present invention has a (meth)acryloyl group and an isocyanate group in the molecule via a urethane bond, and typically consists of acrylic acid or methacrylic acid and a monoepoxy compound. Examples include unsaturated isocyanates which have a (meth)acryloyl group and an isocyanate group in one molecule via urethane by reacting an unsaturated alcohol obtained by the reaction with a polyvalent isocyanate.

An example is shown by the following reaction.

゛ (2-human u4 diethyl methacrytide)
(2,4-)Rylene Isocyanate) (Unsaturated Isocyanate) In the production of this type of unsaturated isocyanate compound, the reaction molar ratio of unsaturated alcohol and diisocyanate is not necessarily adjusted. The presence of free diisocyanate is permissible, and the presence of free diisocyanate is not necessary.

Although it is convenient to carry out the reaction in a solvent or monomer and use it as is, it is not impossible to synthesize without a solvent.

Suitable examples of unsaturated alcohols used in the synthesis of unsaturated isocyanates include 2-hydroxyethyl (meth)acrylate and 2-hydroxypropyl (meth)acrylate.

In addition, as the polyvalent isocyanate, 2.4 tolylene diisocyanate, 2.4 tolylene diisocyanate and 2
, mixture with 6-tolylene diisocyanate, tolydine diisocyanate, diphenylmethane diisocyanate,
Use is made of phenylene diisocyanate, 1,5-naphthylene diisocyanate, 1,6 hexamethylene diisocyanate, isophorone diisocyanate, xylylene diisocyanate, hydrogenated xylylene diisocyanate.

The primer of the present invention contains unsaturated isocyanate alone,
Although it can be impregnated into concrete or cement-based building materials, it is preferable to apply a radical curing resin thereon and cure it to copolymerize the unsaturated groups of the primer with the top coating resin. , it is possible to achieve the objective by finally curing the impregnated resin.

Furthermore, in order to expand the effects of the present invention and to fully achieve the purpose no matter what kind of paint is used as the top coat, a radical generating catalyst may be used in combination as necessary, and (meth)acryloyl groups may be added in the molecule. It is possible to take measures such as using a mixture of a polymerizable monomer copolymerizable with an unsaturated isocyanate having an isocyanate group, or dissolving the polymer in the polymerizable monomer.

The unsaturated isocyanate of the present invention can be cured by various means.For example, the radical generator may be an azo compound, but the adhesion tends to vary.The photoreaction initiator also shows a similar tendency, and when exposed to sunlight. is practical, but adhesion may not be sufficient on cloudy days or in areas not exposed to sunlight.

As the curing agent of the present invention, a redox system using an organic peroxide is suitable. Examples of these include (a) acyl peroxide - aromatic tertiary amines, (b) hydroperoxide - vanadium, cobalt, copper,
Examples include organic acid salts or chelate compounds of manganese, (c) ketone peroxide-cobalt, organic acid salts or chelate compounds of vanadium, and (c) is especially useful when used in combination with a small amount of styrene. Become.

Examples of organic peroxides include the following types.

(i) Ketone peroxides methyl ethyl ketone peroxide, cyclohexanone peroxide, methyl acetoacetate peroxide, (ii) Hydroperoxides cumene hydroperoxide, paramenthane hydroperoxide, (ii) Diacyl peroxides lauroyl peroxide, Benzoyl peroxide, methalyl peroxide, (iv) peroxyesters t-butylperoxybiparate, t-butylperoxy 2-ethylhexanate, t-butylperoxybenzoate, although these can be used alone, Mixed use is also possible if necessary. However, ketone peroxides and hydroperoxides react with isocyanate groups, rapidly gelling, and sometimes foaming, making it difficult to use them in combination with unsaturated isocyanates and relying on spray painting from separate nozzles. It turns out.

Since diacyl peroxide does not exhibit this phenomenon, any coating system can be employed.

The amount of organic peroxide used is 0.2 to 5 parts by weight per 100 parts by weight of the unsaturated isocyanate and polymerizable monomer.
parts by weight, and a suitable amount is 0.5 to 3 parts by weight.

The polymerizable monomer used in the present invention has the effect of improving adhesion and expanding the stress surface, and is a type that can be copolymerized with the unsaturated bond of unsaturated isocyanate, specifically the (meth)acryloyl group. If so, it is available. Those examples include;
For example, the following types can be mentioned:

Styrene, vinyltoluene, chlorostyrene, methacrylic acid esters (methyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, tert-butyl methacrylate, 2-ethylhexyl methacrylate, benzyl methacrylate, cyclohexyl methacrylate, ethylene glycol dimethacrylate) methacrylate, diethylene glycol dimethacrylate, etc.), acrylic esters (methyl acrylate, ethyl acrylate, butyl acrylate,
2-ethylhexyl acrylate, phenoxyethyl acrylate, cyclohexyl acrylate, trimethylolpropane triacrylate, etc.), acrylonitrile, vinylpyrrolidone.

The proportion of these polymerizable monomers to be used is not particularly limited, but is preferably 5 parts or more and 200 parts or less based on 100 parts by weight of the total amount of the unsaturated isocyanate and the unsaturated silane compound.

This does not mean that using more than 200 parts cannot be used, but there is a tendency for the viscosity to decrease and the effectiveness to decrease somewhat. Moreover, if it is less than 5 parts, there is little point in adding it.

Furthermore, it may be useful to dissolve and use a polymer that dissolves in the polymerizable monomer to improve adhesion. A coating film made by mixing an appropriate amount of 100% and hardening it with a radical-generating curing agent adheres extremely well to wet concrete surfaces.

The polymer used here is not particularly limited as long as it is soluble in the monomer; examples thereof include polymethyl methacrylate, polystyrene, polyvinyl acetate, butyl acrylate, and acrylonitrile. copolymer rubber, chlorosulfonated polyethylene, thermoplastic amorphous polyester, ethylene-vinyl acetate copolymer, and the like.

After applying the primer according to the invention to the concrete,
Furthermore, it can be overcoated with a desired paint, and has good adhesion with the topcoat.

It goes without saying that the primer according to the present invention can also be used in combination with fillers, colorants, reinforcing materials, etc., if necessary.

[Example] - Next, examples will be shown below to help understand the present invention.

1 color example 1 Synthesis of unsaturated incyanate (A) 82 g of methyl methacrylate, 174 g of 2.4-) lylene diisocyanate, Prepare 0.05 g of methylbarabenzoquinone and dissolve 1 2-hydroxy 10-vinyl methacrylate in dry air.
44 g was added dropwise over a period of 30 minutes at a temperature of 60°C.

After the dropwise addition was completed, the reaction was continued at the same temperature for 1 hour, then 1.2 g of dibutyltin dilaurate was added, and the reaction was continued for another 1 hour. As a result of infrared analysis, it was determined that approximately 60 (%) of the isocyanate groups had reacted. Unsaturated isocyanate (A) (methyl methacrylate solution) was obtained as a pale yellow liquid.

Adhesion test 30cm x 30c immersed in water at room temperature for 3 days
A concrete board of sX5cm was pulled out of the water and
After leaving it at room temperature for several minutes, wipe the surface with a cotton cloth.

Immediately on this surface, a mixture of 100 parts by weight of unsaturated isocyanate (A) (methyl methacrylate solution), 4 parts by weight of benzoyl peroxide (50% powder), and 0.2 parts by weight of dimethylaniline was added at 50 g/Im.
It was applied with a brush at a ratio of 2:2 and left as it was - day and night.

Next, 2 parts of a paste-like paint, which is viscous at room temperature and is made by adding 0.3 parts of dimethylaniline to 100 parts of T-Coat (trade name, thermosetting resin for acrylic intermediate coating) manufactured by Showa Kobunshi Co., Ltd., was added.
■ Apply a spatula to make it thick, cover the surface with a 50 μm polyethylene terephthalate film, and let it harden overnight.

In the tensile adhesion test using L3 meter,
It showed a weight of 30 to 40 kg (5 measurements), and all of them had broken into the concrete surface by 1 to 2 zm.

Synthesis of Practical Jj 152 Polyunsaturated Isocyanate (B) In a 11 separable flask equipped with a stirrer, a reflux condenser, a thermometer with a gas introduction tube, and a dropping funnel, 134 g of phenoxyethyl methacrylate, 222 g of isophorone diisocyanate, and 0 rosebenzoquinone were added. 2-hydroxypropyl methacrylate 1 in a stream of dry air at a temperature of 70°C.
After 0 dropwise addition of 44 g, the reaction was carried out at 70 to 75° C. for 3 hours, and as a result of infrared analysis, it was estimated that the free isocyanate groups were about 46 (%).

Unsaturated incyanate (B) (phenoxyethyl methacrylate solution) was obtained in the form of a pale yellowish brown liquid.

Adhesion test Lambda sizing (cement-asbestos building material) manufactured by Showa Denko Kenzai Co., Ltd. was cut into 30c rings and immersed in water at room temperature for 3 days.

Immediately after pulling up the surface, the surface was wiped with a dry cloth, and the following formulation was immediately applied at a concentration of 100 g/m'', and left to cure day and night.

In a tensile adhesion test using an Elcometer using approximately 32% polymethyl methacrylate as an adhesive, 65 parts by weight of benzoyl peroxide, 5 parts by weight of dimethylaniline, and 0.3 parts by weight of epoxy resin, the measured values at five locations were all 25 kg. All of the above were material fractures.

Example 3 Synthesis of unsaturated isocyanate (C) A 11-separable flask equipped with a stirrer, a reflux condenser, a thermometer with a gas introduction tube, and a dropping funnel was charged with 2.4-)
174 g of lylene diisocyanate and 0.05 g of methylbarabenzoquinone are charged, and 144 g of 2-hydroxyethyl methacrylate is added dropwise in dry air at a temperature of 60° C. over 30 minutes.

After the dropwise addition was completed, the reaction was carried out at the same temperature for 1 hour, and then 1.2 g of dibutyltin dilaurate was added, and the reaction was further carried out for 1 hour to obtain unsaturated isocyanate (C) in the form of -1 pale yellow liquid. As a result of infrared analysis, approximately 60 (%) of isocyanate groups
It was determined that there was a reaction.

Adhesion test An adhesion test was conducted in the same manner as in Example 1 using the following mixture. However, the thickness of the brush coating was 70 g/va2.

Unsaturated isocyanate compound (C) 100 parts by weight Benzoyl peroxide (50% powder) 3 parts by weight Dimethylaniline 0.2 parts by weight In a tensile adhesion test using an elcometer, 25 to 30 kg (
5 measured value ranges), all of which showed the state of fracture that had penetrated to a depth of 1 to 2 IV from the surface of the concrete and hardened.

An adhesion test was conducted in the same manner as in Example 1 using the mixture shown below. However, the thickness of the brush coating was 70 g/m2.

Dimethylaniline 0.2 parts by weight In a tensile adhesion test using an Elcometer, 20 to 2 parts by weight.
5 kg (range of 5 measured values), and all of them showed a state of hardening that had penetrated to a depth of 1 to 2 cm from the surface of the concrete.

〔Effect of the invention〕

The primer according to the present invention is mainly composed of an unsaturated isocyanate compound, and also contains a polymerizable monomer if necessary, so it can be used on concrete with pores and cracks, or concrete whose surface has deteriorated over time. It penetrates well and hardens, and it also adheres well to wet concrete surfaces, forming a coating that prevents moisture and gas from entering.

Furthermore, since this primer has good adhesion to topcoat paints, a desired topcoat can be applied thereon, which is useful for preventing deterioration of concrete structures and maintaining their aesthetic appearance.

Claims (2)

[Claims] (1) An unsaturated isocyanate having a (meth)acryloyl group and an isocyanate group via a urethane bond in the molecule, and optionally a polymerizable monomer, and a polymer dissolved in the polymerizable monomer. A primer containing a coalescing and hardening agent. (2) The primer according to claim 1, which contains an organic peroxide as a curing agent.