JPS584942B2 - Curable resin composition for undercoat - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a curing undercoat used as an undercoat paint for a light-curing paint used for painting building materials (particularly for painting exterior building materials such as cement, asbestos cement, slate boards, and roof tiles). The present invention relates to a synthetic resin composition.

As a paint for painting building materials, it has a good appearance, does not fade, and is weather resistant.
It is required to have excellent water resistance.

In order to satisfy these conditions, conventional
0-minute low-temperature baking type paints were used, but the appearance of the paint film (sharpness, gloss) was poor, and the baking method required a large amount of thermal energy for baking, and the paint film failed due to variations in heat conduction to the material. There are problems such as uneven curing, a long process time due to the need for heating, temperature raising, and cooling, and a limit to the ability of the paint to have a high solidity.

In view of these problems, the present inventors investigated the use of photocurable paints.

However, photo-curing paints do not require the use of solvents, and clear coatings have an excellent appearance, but cannot be colored with sufficient hiding power.

Pigments cannot be added to photocurable paints that have been colored by adding pigments, since light does not easily pass through them, resulting in insufficient curing.

Therefore, there is a need for an undercoat paint for photo-curing paints that hides the paint.

In order to solve these problems, the present invention aims to provide a curing undercoat that has sufficient hiding properties and exhibits sufficient properties as a photocurable undercoat used for painting building materials. A resin composition is provided.

That is, the present invention provides an initial condensate obtained by condensing (A) (a) a dibasic acid having no ethylenically unsaturated bond or an ester-forming derivative thereof and (b) a dihydric alcohol;
) urethane with an organic diisocyanate, and react in a molar ratio such that (b)/{(a)+(c)} is 1 to 1.1 and (a)/(c) is 5 to 100. The present invention relates to a curable resin composition for undercoating, which contains the resulting urethane-modified polyester (B), a polyisocyanate compound as a curing agent, and (C) a pigment, and is used as an undercoat for a photocurable paint for coating building materials.

Dibasic acid component of urethane-modified saturated polyester [(a
) components] include dibasic acids such as phthalic acid, isophthalic acid, terephthalic acid, adipic acid, sebacic acid, and naphthalene dicarboxylic acid, their acid anhydrides, and ester-forming derivatives such as their alkyl esters.

Dihydric alcohol components [component (b)] include polyethylene glycols such as ethylene glycol and diethylene glycol, polypropylene glycols such as propylene glycol and dipropylene glycol, neopentyl glycol, butanediol, and 2,2-bis(p-2-oxyphenyl). 4.) Organic diisocyanates (component (C)) include propane, aliphatic diisocyanates such as hexamethylene diisocyanate and trimethylhexamethylene diisocyanate, cycloaliphatic diisocyanates such as xylylene diisocyanate, and tolylene diisocyanate; Examples include aromatic diisocyanates such as 4'-diphenylmethane diisocyanate, and the above compounds may be used in combination.

Aliphatic diisocyanates are preferred from the viewpoint of yellowing resistance, but aromatic diisocyanates are preferred from the viewpoint of addition reaction rate.

The manufacturing method is to first prepare a dibasic acid and a dihydric alcohol at 150~
5 to 15 at 280°C, preferably 200 to 260°C
Allow time to react.

At this time, there is no problem in using a known ester catalyst, such as dibutyltin oxide, dibutyltin dilaurate, etc., in an amount of 0.05 to 1% by weight based on the amount of raw materials charged.
is sufficient to reach your goal.

The reaction can be carried out under normal pressure or under increased pressure, but it can also be carried out in the presence of an organic solvent such as xylene.

Next, in the urethanization reaction with an organic diisocyanate, in order to perform the reaction uniformly, toluene, methyl ethyl ketone, ethyl acetate, xylene, cellosolve acetate, Solbetsuso 100, Solbetsuso 15 are preferably used.
It is preferable to dissolve the above-mentioned condensate in the presence of an organic solvent such as 0 (trade name: aromatic solvent manufactured by Etsuso Standard Oil Co., Ltd.), and to react the organic diisocyanate dropwise.

The reaction temperature is 50° C. to 150° C. Preferably, in order to further promote the reaction, an appropriate amount of a known catalyst such as a metal compound such as tin may be added.

For example, dibutyltin oxide used as an esterification catalyst can also be used as a catalyst in the urethanization reaction.

The above (a), (b) and (C) components have a molar ratio of (
b). / {(a)+(c)) is blended so that it becomes 1 to 1.1.

If it is less than 1, unreacted isocyanate groups remain after urethanization, which is unfavorable in terms of coating film properties, and if it exceeds 1.1, it becomes difficult to increase the molecular weight.

Furthermore, components (a) and (C) have a molar ratio of (a)/(c).
) is blended so that it is 5 to 100.

If the molar ratio is less than 5, the concentration in the resulting linear saturated polyester will be high and the solubility in solvents will be reduced, and if the molar ratio exceeds 100, it will be difficult to increase the molecular weight.

Preferably (a)/(c) (molar ratio) is 10 or less.

In addition, you may use less than 5 weight% of trifunctional or more polyhydric alcohols in an alcohol component.

When it exceeds 5% by weight, it becomes impossible to increase the molecular weight.

As the diluting solvent, organic solvents such as xylene, Solbetsuso 100 (Esso Standard Oil ■ trade name), Solbetso 150 (Esso Standard Oil ■ trade name), cellosolve acetate, butyl cellosolve, etc. are used as appropriate.

Examples of the curing agent (polyisocyanate compound) which is component (B) of the present invention include hexamethylene isocyanate derivatives of isocyanates having a bempene term such as tolylene diisocyanate and xylylene diisocyanate, and prepolymers thereof.

As the polyisocyanate compound, hexamethylene diisocyanate derivatives are preferred from the viewpoint of yellowing resistance, and commercially available products include Desmodur NC (trade name of Bayer AG),
Coronatonol (Japan Polyurethane Industries ■trade name) is available.

The curing agent (B) and the prisoner component have an equivalent ratio of NCO/OH of 5 to 5.
The ratio is 10/1 to 10/10.

Component (C) includes titanium white, red iron, yellow lead, carbon black, etc., and is a compounding agent for the purpose of coloring.

Component (C) is used in an amount of 10 to 50% by weight, preferably 30 to 40% by weight, based on the total solid content in order to provide sufficient hiding power.

The photocurable paint for painting building materials in the present invention is not particularly limited as long as it contains a photopolymerizable resin and a photosensitizer and can be used for painting building materials.

Examples of the photopolymerizable resin include epoxy ester resins, isocyanate-modified epoxy ester resins obtained by reacting the resins with polyisocyanates, and polyesters such as polyester unsaturated carboxylates containing functional groups reactive with OH groups or carboxyl groups. There are polyesters having terminal unsaturated groups obtained by reacting vinyl monomers having terminal unsaturated groups, urethane prepolymers having terminal unsaturated groups, and the like.

The above-mentioned epoxy ester resin is, for example, an epoxy ester compound having a hydroxyl group obtained by an addition reaction between an epoxy compound having one or more epoxy groups and an unsaturated monobasic acid or polybasic acid.

The above-mentioned epoxy compounds are bisphenol A type epoxies such as acrylic acid glycidyl ester, methacrylic acid glycidyl ester, glycide, ethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, 1,4-butanediol glycidyl ether, and bisphenol A diglycidyl ether. resins, hexahydrophthalic acid diglycidyl ester, fucuric acid diglycidyl ester, epoxidized polybutadiene, epoxidized linseed oil, and the like.

Examples of unsaturated monobasic acids include acrylic acid, meccrylic acid, etc.
Examples of unsaturated polybasic acids include maleic acid and fumaric acid.

A known method for forming an ester bond by reacting an epoxy group with a carboxyl group can be applied to the above addition reaction.

For example, an ester bond is formed by reacting at 60 to 200°C in the presence of an alkaline catalyst.

The epoxy compound and acid have an equivalent ratio of epoxy group/carboxyl group of 0. It is preferable that the ratio is 971 to 1.1/1.

An isocyanate-modified epoxy ester resin can be obtained by subjecting such an epoxy ester resin to a urethanization reaction with a polyisocyanate. In this case, the amount of polyisocyanate is 0.01% of the isocyanate group per equivalent of total hydroxyl groups in the epoxy ester. It is preferably used in a proportion of 1 to 1 equivalent, preferably 0.5 to 1 equivalent.

Examples of catalysts used in this urethanization reaction include dibutyltin dilaurate, dibutyltin di-2-
Tin compounds such as ethylhexoate and dibutyltin diacetate are commonly used, but the reaction proceeds even without the addition of a catalyst.

The reaction temperature is preferably 20 to 80°C,
The reaction is allowed to proceed until the isocyanate groups are completely consumed.

Further, the urethanization reaction can be carried out, if necessary, in a solvent or polymerizable monomer that does not react with isocyanate groups.

The above polyisocyanates include tolylene diisocyanate, xylylene diisocyanate, diphenylmethane diisocyanate, hexamethylene diisocyanate,
Pentamethylene diisocyanate, naphthylene-1,5
-diisocyanate, 3,3cydimethyldiphenyl-4
, 4L diisocyanate, isophorone diisocyanate, lysine diisocyanate, etc. In addition, isocyanate prepolymers having two or more isocyanate groups synthesized from the above-mentioned isocyanates and polyhydric alcohols, such as Coronate HL (all products manufactured by Nippon Polyurethane Industries) names), etc.

Polyester unsaturated carboxylates are polybasic acids that do not have polymerizable unsaturated bonds, such as adipic acid, sebacic acid, phthalic acid, and hexahydrophthalic acid, or their acid anhydrides, and ethylene glycol, propylene glycol, butanediol, etc. It is a compound obtained by reacting a polyester having a terminal hydroxyl group obtained by ester condensation reaction of a polyhydric alcohol that does not have a polymerizable unsaturated bond with an unsaturated carboxylic acid such as acrylic acid or meccrylic acid. Also, the compound obtained by reacting the polyester having a terminal hydroxyl group or carboxyl group produced as described above with an unsaturated monomer reactive with the hydroxyl group or carboxyl group such as glycidyl methacrylate or glycidyl acrylate is terminally unsaturated. It can be used as a polyester with groups.

The urethane prepolymer having a terminal unsaturated group is obtained by reacting a polyol with a polyisocyanate.

It is a compound obtained by reacting a terminal isocyanate urethane polymer with an unsaturated monomer reactive with an isocyanate group such as β-hydroxyethyl methacrylate or β-hydroxyethyl acrylate.

Examples of the polyol include polyethylene glycol and polypropylene glycol, and examples of the polyisocyanate include those shown above.

Examples of the photosensitizers include benzphenone, benzoiso,
In addition to carbonyl compounds such as benzisoethyl ether, benzisoisopropyl ether, benzyl, diacetyl, acetophenone, and anthraquinone, there are many photosensitizers such as sulfides and halogen compounds.

These photosensitizers can be used alone or in combination of two or more types, but if the amount used is too small, the curing speed will be slow, and if the amount is too large, there is a limit to the curing speed, and due to the nature of the cured product. It is also economically unfavorable.

In order to compensate for these drawbacks, sensitizing aids such as amines are used as photosensitizers.

Examples of amines include primary amines containing at least one amine group in the molecule, such as butylamine, hexamethylenediamine, diethylenetriamine, monoethanolamine, and diethylamine, dimethylaniline,
If necessary, a photopolymerizable monomer can be added to the above-mentioned photocurable coating material, which includes secondary or tertiary amines such as pyridine, diethanolamine, and triethanolamine.

Photopolymerizable monomers include acrylic acid esters such as methyl acrylate, ethyl acrylate, butyl acrylate, ethylene glycol diacrylate, 1,6-hexanediol diacrylate, butanediol diacrylate, trimethylolpropane triacrylate, and methyl methacrylate. , methacrylic acid esters such as ethyl methacrylate, butyl methacrylate, ethylene glycol dimethacrylate, 1,6-hexanediol dimethacrylate, butanediol dimethacrylate, trimenalol propane trimethacrylate, and vinyl compounds such as styrene and its derivatives. One or more of these may be used.

An example of the composition of the above-mentioned components in a photocurable paint is as follows.

That is, 10 to 99 parts by weight of the photopolymerizable resin, 1 to 90 parts by weight of the photopolymerizable monomer, and 0.1 to 10% by weight of the photosensitizer based on 100 parts by weight of these components in total, When using a sensitizing agent, it is 10% by weight based on the total amount of polymerization components.
Used below.

The method for coating building materials is to preheat the building materials at about 50 to 60°C, then apply the curable resin composite for undercoating according to the present invention by spraying, etc., and apply the photocurable paint after or before completely drying. This is done by applying it by spraying or the like and irradiating it with light.

Examples of manufacturing the urethane-modified polyester of the present invention are shown below.

Hereinafter, parts are by weight. Production Example 1 Esterification reaction> 249 parts of terephthalic acid, 249 parts of isophthalic acid, 93 parts of ethylene glycol, 176 parts of neobentyl glycol.
8 parts were reacted at 240° C. for 10 hours under an inert gas atmosphere to obtain an initial condensate having an acid value of 5.

At this time, 1.1 parts of dibutyltin oxide was used as a catalyst.

<Urethane compound> After dissolving 400 parts of the above initial condensate (A) in 600 parts of a mixed solvent of xylene/cellosolve acetate = 1/1 (weight ratio), it was dissolved at 100°C under an inert gas atmosphere. 20 parts of hexamethylene diisocyanate was added dropwise.

After dropping for 1 hour, the mixture was kept at a constant temperature for 2 hours to obtain a saturated polyester (5) with a Gardner viscosity of Z-Z.
)/((a)+(c)) molar ratio is 1.00 and (
The a)/(C) molar ratio was 15, with an acid value of 2 and a hydroxyl value of 5.

Production example 2 <Esterification reaction> 249 parts of terephthalic acid, 249 parts of isophthalic acid, ■, 4
310.5 parts of butanediol and 1.1 parts of dibutyltin oxide were reacted at 240°C under an inert gas atmosphere.
An initial condensate (B) with an acid value of 5 was obtained in 0 hours.

Urethane formation reaction> After 400 parts of the initial condensate (B) was dissolved in 600 parts of a mixed solvent of xylene/cellosolve acetate = 171 (weight ratio), 40 parts of hexamethylene diisocyanate was added dropwise at 100°C over 1 hour. After 2 hours of reaction, a saturated polyester with a viscosity of Z1 was obtained (b)
/((a)+(c)) The molar ratio is 1,01 and (a)/
(C) molar ratio is 7.2, acid value 1, hydroxyl value 5
Met.

Next, examples of the present invention will be shown.

Examples The urethane-modified polyester obtained in Production Example 1 or 2 and the polyisocyanate compound (Coronate HL, trade name of Nippon Polyurethane Industries) were further mixed with titanium white so that the equivalent ratio of hydroxyl groups to isocyanate groups was 1/1. Blend the solid content to 45% by weight, dilute with a mixed solvent of toluol/butyl acetate at a weight ratio of 1/1 in a Ford cup #4 for 15 to 20 seconds (25°C), and The curable resin composition for undercoat according to the invention was manufactured, and after preheating the dust-removed cement tile at about 50° C., the above curable resin composition for undercoat was spray-coated.

After this, either immediately or after heating and drying at 80°C for 24 hours, an ultraviolet curing paint (Hykroid 5500D, Hitachi Chemical Co., Ltd. brand name) containing epoxy acrylate as a main component is spray-painted on top of the coating, and a high pressure of 2 kW output is applied. It was cured by irradiating it with light from a 10 cm distance for 12 seconds using a mercury lamp.

At this time, the undercoat layer had a film thickness of 30μ, and the topcoat layer had a film thickness of 60μ.

Table 1 shows the results of tests using this.

Comparative Examples 1-2 Commercially available acrylic lacquer (Hytaloid 1
005, Hitachi Chemical (trade name) (comparative example 1)
In addition, commercially available acrylic emulsion paint (Hykroid 80
03, using Hitachi Chemical (trade name) (comparative example 2),
The rest was tested in the same manner as in Example 1.

The results are shown in Table 1. Comparative Example 3 After preheating the dust-removed tile at approximately 50°C, a commercially available acrylic urethane paint (Hytaloid 3083, Hitachi Chemical Co., Ltd. trade name and Coronate HL1 Nippon Polyurethane Kogyo Co., Ltd. trade name) was mixed and spray-painted. 5~ at °C
After drying for 10 minutes, the above paint was spray coated as a top coat, dried at 60°C for 1 hour, and after cooling, the paint film was cured for 24 to 48 hours.

Thereafter, a test was conducted in the same manner as in Example 1.

The results are shown in Table 1. Comparative Example 4 Acrylic lacquer paint (Hykroid 1005, Hitachi Chemical Co., Ltd. trade name) instead of commercially available acrylic urethane paint
The same procedure as in Comparative Example 3 was conducted using .

The test results are shown in Table 1. As is clear from the above, the curable resin composition for undercoat according to the present invention has sufficient hiding power and can be used as an undercoat for photocurable paint for painting building materials.
It satisfied sufficient characteristics.

By using the curable resin composition for undercoating of the present invention, it is possible to effectively use a photocurable paint that has a solid content of 100% and takes a short time to complete coating.

Claims (1)

[Scope of Claims] 1 (A) (a) A dibasic acid having no ethylenically unsaturated bond or an ester-forming derivative thereof, and (b)
) The initial condensate obtained by condensation reaction of dihydric alcohol is urethanized with (c) organic diisocyanate, and the molar ratio (b)/((a)+(c)) is 1 to 1.
．． Urethane-modified polyester obtained by reacting 1 and (a)/(c) so that it is 5 to 100, (B)
A curable resin composition for undercoating, which contains a polyisocyanate compound as a curing agent and (C) a pigment, and is used as an undercoat for a photocurable paint for painting building materials.