JPS62241971A - Coating - Google Patents

Abstract

PURPOSE:To obtain a coating which gives an extremely thin coating film having excellent adhesiveness, flex resistance, surface hardness, salt-water resistance, etc., and is useful as a coating applied to the inside of a can for canned goods, by using a specified diene polymer as principal component. CONSTITUTION:A liquid diene polymer (A) having terminal (meth)acryloyl groups is obtained by reacting a liquid diene polymer (a) having terminal hydroxyl groups (e.g., a liquid polybutadiene) with a reaction product (b) of (meth)acrylic acid with a polyisocyanate. A liquid diene polymer (B) having terminal carboxyl groups is obtained by reacting component (a) with an unsaturated carboxylic acid (anhydride) (c). A liquid diene polymer (C) having terminal epoxy groups is obtained by reacting component (a) with, e.g., epichlorohydrin (d). A liquid diene polymer (D) having terminal hydroxyl groups and having epoxy groups in the molecular chain is obtained by reacting component (a) with, e.g., peracetic acid (e). One or more components selected from components A-D are diluted with a diluent.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a coating material that can be applied extremely thinly and has excellent properties, particularly on the inner surface of a can. Regarding paints suitable for paints.

[Problems to be solved by conventional technology and invention]

The inner surface of canning cans is usually coated with 0.1 to 10.0 mil (l mil-
An extremely thin coating film of 25.4 μm) is formed. This coating has moderate surface hardness, excellent adhesion, bending resistance, acid resistance, alkali resistance, salt water resistance,
Hot water resistance is required.

As a coating material used for the purpose of forming such a coating film, a coating material whose main component is liquid polybutadiene having a hydroxyl group at the end of the molecular chain is conventionally known. However, this paint can form a thin film, and although the thin film has excellent density and bending resistance, it has (1) low surface hardness, and (2) poor acid resistance, alkali resistance, and salt water resistance.

(3) There were many points that needed improvement, such as poor hot water resistance.

[Means for solving problems]

The present inventors have conducted intensive research to overcome the above-mentioned conventional drawbacks, and as a result, an excellent coating material has been developed by variously chemically modifying the conventional liquid polybutadiene (diene polymer) having a hydroxyl group at the end of the molecular chain. The present invention was completed based on this finding.

That is, the present invention provides a liquid diene polymer (A) having a (meth)acryloyl group at the end of its molecular chain, (B) a liquid diene polymer having a carboxyl group at the end of its molecular chain, and (B) an epoxy group at the end of its molecular chain. Liquid diene polymer (C)
and a liquid diene polymer (D) having a hydroxyl group at the end of the molecular chain and an epoxy group within the molecular region. .

The paint of the present invention has as a main component any one of the above polymers (A) to (D) or a mixture of two or more polymers selected from polymers (A) to (D). . These polymers (A) to (D) have, for example, 6i of water at the end of the molecular chain.
It can be obtained by using a liquid diene-based polymer having a group as a raw material and chemically modifying it by an appropriate method.

There are various types of liquid diene polymers that can be used as the raw material, but preferably liquid diene polymers have a hydroxyl group at the end of the molecular chain, and their number average molecular weight is usually 5.
00~20000. Preferably SOO~8000. Viscosity 0.1~10000voice/30℃, preferably 10~
5000 Boise/30℃, Hydroxylic Fund ff10.1~l
Omeq/g% preferably 0.5-5 meq/g
I can give you something. Particularly preferred is liquid polybutadiene that satisfies all of these conditions. This liquid polybutadiene is produced by heating and polymerizing butadiene in the presence of hydrogen peroxide in a solvent such as alcohol, preferably isopropyl alcohol, at a temperature of 50 to 170°C and a pressure of 1 to 50 kg/ctAG for 0.5 to 10 hours. It can be manufactured by

The polymer (A) in the present invention is a liquid diene polymer having an acryloyl group or a methacryloyl group at the end of the molecular chain. This polymer (A) particularly has a number average molecular weight of 500 to 20,000. Preferably 1000-10000
．． , viscosity 5-20000 poise/30°C, preferably l
A temperature of 0 to 5,000 voids and 730°C is suitable. Further, the content of (meth)acryloyl groups per molecule of the polymer (A) is preferably about 1.5 to 3. Polymer (A) is (
It may have meth)acryloyl groups at both ends of the molecular chain, only at one end, or a mixture thereof.

The polymer (A) can be produced, for example, by reacting the aforementioned raw material (liquid diene polymer having a hydroxyl group at the end of the molecular chain) with a reaction product of acrylic acid or methacrylic acid and a polyisocyanate compound. This reaction generally does not require a solvent, and the reaction conditions are not particularly limited, but are usually set at a temperature of θ to 100°C and a pressure of normal pressure for 2 hours and 0.5 to 10 hours. An example of the polymer (8) obtained in this way is represented by the following structural formula (1)
It is as follows.

Next, the polymer (B) in the present invention is a liquid diene polymer having a carboxyl group at the end of the molecular chain. In particular, the polymer (B) has a number average molecular weight of 500 to 20,000.
, preferably 1000-10000, viscosity 1-2000
0 voids/30°C, preferably 10 to 5000 voids/
9 polymers (30°C, acid value 1 to 100 ■KO II /g, preferably 5 to 80 ■KOII / g)
B) may have carboxyl groups at both ends of the molecular chain, only at one end, or a mixture thereof; 1) coalescence (
B) is produced, for example, by reacting the aforementioned raw material (liquid diene polymer having a hydroxyl group at the end of the molecular chain) with an unsaturated carboxylic acid or its anhydride (e.g. maleic anhydride, itaconic anhydride, fumaric acid, etc.). can do. This reaction generally does not require a solvent, and the reaction conditions are not particularly limited, but are usually set at a temperature of 25 to 150°C and a pressure of 1 hour to normal pressure for 1 to 20 hours. The structural formula of an example of the polymer (8) thus obtained is as shown in formula (U) below.

Next, the polymer (C) in the present invention is a liquid diene polymer having an epoxy group at the end of the molecular chain.

In particular, the polymer (C) has a number average molecular weight of 1500 to 20
000, preferably 1000-10000° viscosity 1-1
0,000 voids/25°C, preferably 10 to 5,000 voids/25°C, and an epoxy equivalent of 100 to 10,000, preferably 500 to 7,000. Polymer (
C) may have an epoxy group at both ends of the molecular chain, only at one end, or a mixture thereof. solvents (e.g. benzene, toluene.

It can be produced by reacting the aforementioned raw material (liquid diene polymer having a hydroxyl group at the end of the molecular chain) with epichlorohydrin or the like in xylene, etc.). The reaction conditions at this time are not particularly limited, but usually the reaction temperature is 0-1
Set at 00°C, 2 reaction pressures, and 1 reaction time, 1 to 20 hours. The structural formula of an example of the polymer (C) obtained in this manner is as shown in formula (II) below.

Next, the polymer (D) in the present invention is a liquid diene polymer having a hydroxyl group at the end of the molecular chain and an epoxy group within the molecular region. 500-20000, preferably 1000-1
0000. Viscosity 5-toooo voids/45°C, preferably 10-5000 voids/45°C, hydroxyl group content ff10
．． 1-10 meq/g% preferably O-5-5 m
eq/g: x boxy equivalent 10-10000. Preferably, 100 to 5000 is suitable. Polymer (
D) may have a hydroxyl group at both ends of the molecular chain, only at one end, or a mixture thereof. Polymer (D) can be produced, for example, by reacting the above-mentioned raw material (liquid diene polymer having a hydroxyl group at the end of the molecular chain) with peracetic acid, etc. in a suitable solvent (for example, pentane, hexane, heptane, cyclohexane, etc.). can do. The reaction conditions at this time are not particularly limited, but the reaction temperature is usually 0 to 15
The reaction time is set at 0° C., normal pressure, and 0.1 to 10 hours. An example of the polymer (D) obtained in this way is represented by the structural formula (IV) described below.

° In the present invention, any of the above-mentioned polymers (A) to (D) may be used alone, or two or more of these polymers (A) to (D) may be selected as a mixture to form the coating composition of the present invention. Used as the main component. In addition, - of the above polymers (8) to (D)
For example, they can be represented by the following formulas (1) to (IV), respectively.

In the present invention, the above-mentioned main components can be diluted with an appropriate diluent and used. In addition to the above-mentioned main components, it is also possible to add suitable additives depending on the intended use of the coating material of the present invention.

The method of using the paint of the present invention is extremely simple; for example, the paint of the present invention may be applied or sprayed onto the object to be coated, and then heat treated (baked).
Here, the conditions for heat treatment are usually 150 to 250°C;
Preferably at a temperature of 180 to 220°C for 5 to 60 minutes,
Preferably, it is sufficient to heat for 8 to 20 minutes.

〔Effect of the invention〕

The coating film obtained by applying the coating material of the present invention, such as the one on the ridge, not only has excellent adhesion (especially adhesion to metals such as steel plates) and bending resistance, but also has appropriate surface hardness. It also has excellent acid resistance, alkali resistance, salt water resistance, hot water resistance, etc. Moreover, according to the paint of the present invention, the thickness is 0.1~
Very thin coatings of 10.0 mils (2.54-254 microns) can be formed.

Therefore, the paint of the present invention can be used not only as a general paint for various objects (metals, plastics, wood, etc.), but also as a particularly effective paint for the inner surface of cans, and the contents of can material components It is possible to effectively prevent elution and contamination into substances.

〔Example〕

Next, the present invention will be explained in detail with reference to examples.

Production Example 1 140g of isopropanol and 15g of hydrogen peroxide (concentration 60%) were placed in a stainless steel autoclave, and the air inside the autoclave was vacuum degassed while cooling.Next, 125g of 1,3-butadiene was charged. After charging a predetermined amount, the temperature was raised to 125° C. in about 60 minutes. Thereafter, the reaction was carried out with stirring for 3 hours.

After the reaction is completed, the reaction mixture is cooled and unreacted 1,3
-Butadiene was removed, then 1 liter of distilled water was added, and the resulting polymer was fractionated after shaking and washing using a separating funnel. Furthermore, using a rotary evaporator, 75-8
Purification was carried out at 0° C. and 15 mHg for 4 hours to obtain transparent liquid polybutadiene having a hydroxyl group at the end of the molecular chain. This product has a number average molecular weight of 2 JI OO, a viscosity of 50 boids/30°C, and a hydroxyl group content of 0, 83 meq/g T! Production Example 2 200 g of liquid polybutadiene having a hydroxyl group at the end of the molecular chain produced in Production Example 1, 45.8 g of lylene diisocyanate-hydroxyethyl acrylate (1 hydroxyl (OH) of liquid polybutadiene having a hydroxyl group at the end of the molecular chain) molar ratio of tolylene diisocyanate-hydroxyethyl acrylate isocyanate group (NGO), NGO
loH-1,0), and further added 0.2 g of dibutyltin dilaure) and 0.0 g of p-quinone as a thermal polymerization inhibitor.
．． 2 g and stirred under argon atmosphere for 65 minutes.
The reaction was carried out at .degree. C. for 4 hours to obtain liquid polybutadiene having an acryloyl group at the end of the molecular chain. The number average molecular weight of this material is 3000, and the viscosity is 4100 voids/30
℃, and the acryloyl group content was 2.3 pieces/molecule.

Production Example 3 100g of the liquid polybutadiene having a hydroxyl group at the end of the molecular chain produced in Production Example 1, 7.0g of maleic anhydride, and 0.01g of paraquinone were mixed and reacted at 70°C for 6 hours with stirring under a nitrogen stream. A liquid polybutadiene having a carboxyl group at the end of the molecular chain was obtained. The number average molecular weight of this product is 3000, and the viscosity is 150 voids/3.
The temperature was 0°C, and the acid value was 43 OH/g.

Production Example 4 100 g of the liquid polybutadiene having a hydroxyl group at the end of the molecular chain produced in Production Example 1, and 15 g of luene.

Mix 0.1g of boron trifluoride ethyl ether and heat at 60°C.
After heating to 60° C., 6 g of epichlorohydrin was gradually added and the reaction was carried out at 60° C. for 2 hours.

Next, 7 g of a 45% by weight aqueous sodium hydroxide solution was added, and the reaction was further carried out at 30° C. for 5 hours.

After the reaction was completed, the reaction mixture was washed with water and toluene was removed to obtain liquid polybutadiene having an epoxy group at the end of the molecular chain. The number average molecular weight of this product is 3200,
The viscosity is 120 boids/25°C and the epoxy equivalent is 1
It was 450.

Production Example 5 After raising the temperature to the temperature at which the molecular chain produced in Production Example 1 had a hydroxyl group at the end, a reaction was carried out at 70°C for 2 hours.

After the reaction was completed, the reaction mixture was washed three times with distilled water at 300 mA, and then cyclohexane was distilled off to obtain a liquid polybutadiene having a hydroxyl group at the end of the molecular chain and an epoxy group within the molecular domain. The number average molecular weight of this product is 3300
The viscosity is 360 poise/45°C, and the hydroxyl base is 1! IO, 80 meq/g, and the epoxy equivalent is 2
It was 00.

Examples 1-4. Comparative Example The coatings shown in Table 1 were applied onto a steel plate and heat-treated (baked) at 200° C. for 15 minutes to form a coating film with a thickness of 0.5 mil. Regarding the steel plate on which this coating was formed, JIS K
Evaluation was made in accordance with 5400. The results are shown in Table 1.

Claims (2)

[Claims] (1) Liquid diene polymer (A) having a (meth)acryloyl group at the end of the molecular chain, liquid diene polymer (B) having a carboxyl group at the end of the molecular chain, liquid diene having an epoxy group at the end of the molecular chain A paint whose main component is at least one liquid diene polymer selected from a liquid diene polymer (C) and a liquid diene polymer (D) having a hydroxyl group at the end of the molecular chain and an epoxy group within the molecular region. . (2) The paint according to claim 1, wherein the paint is a baking paint.