JPH07133462A - Resin composition for coating - Google Patents

Abstract

PURPOSE:To obtain the composition excellent in printability, blocking resistance and boiling water resistance, useful for coating cans or metals, by incorporating a copolyester of specific composition with an alkyl etherified formaldehyde as crosslinking agent. CONSTITUTION:The composition can be obtained by incorporating (A) a copolyester produced from (1) as acid component(s), 70-100mol% of an aromatic dicarboxylic acid and 0-30mol% of an aliphatic dicarboxylic acid, (2) as glycol components, 20-60mol% of 1,9-nonanediol and 20-60mol% of a tricyclodecanedialkanol and (3) 1-10mol%, based on the whole acid component, of a >= tri-functional polycarboxylic acid and/or 1-10mol%, based on the whole alcohol component, of >= tri-hydric polyol with (B) pref. 1-50wt.%, based on the component A, of an alkyl etherified formaldehyde (e.g.) methoxylated methylol urea).

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a resin composition for paints, and more specifically, it is used for coating cans and metals, and has excellent printability and blocking resistance, and particularly excellent boiling water resistance (retort resistance). The present invention relates to a resin composition.

[0002]

2. Description of the Related Art Painted metal cans have been widely used as beverages, foods, and other types of packaging containers. The outer surface of these cans is printed and painted for the purposes of metal feed protection, aesthetics, and display of contents. The coating on the outer surface of the can has a multi-layered structure. As a general coating, a primer called size coating is applied to a surface-treated metal plate, and then an intermediate coating called white coating (usually white type) is provided, and printing is performed on this. It Furthermore, a finish varnish coating is applied on the surface for protection and improving the finished appearance.

When the resin for paint is used for size coating and white coating, the main performance requirements are that when printed, there is no bleeding and no repellency (printability), and adhesion to the substrate Well, it does not block even if coated plates are stacked (blocking resistance), and further, when the retort treatment (130 ° C x 30 minutes) for sterilizing the inner surface of the can in food can applications does not cause damage to the coating film (Retortability) and the like.

Conventionally, acrylic resins, epoxy resins, alkyd resins, phenol resins, polyester resins and the like have been known as resins for can paints. However, not only in these systems but also in these blend systems, no coating resin has been invented that can satisfy all of printability, blocking resistance and retort property.

[0005]

DISCLOSURE OF THE INVENTION The present invention is used as a resin for a size coat and / or white coat paint in a system in which an alkyl etherified formaldehyde is added to a polyester resin, and has printability, blocking property,
The present invention relates to a resin composition suitable for a can coating material of a copolyester resin excellent in all retort properties.

[0006]

DISCLOSURE OF THE INVENTION The inventors of the present invention continued their research to solve the drawbacks of polyester resin such as printability, blocking property and retort property. As a result, aromatic dicarboxylic acid and aliphatic dicarboxylic acid were used as dicarboxylic acid components. To compound an alkyl etherified formaldehyde into a copolyester consisting of an acid, 1,9-nonanediol and tricyclodecane dialkanol as a glycol component, and a polycarboxylic acid and / or polyol having a valence of 3 or more as a branching agent. As a result, they have found that they are extremely excellent in printability, blocking ability, and retortability, and have reached the present invention.

That is, in the present invention, the acid component is 70 to 100 mol% of aromatic dicarboxylic acid and 0 to 3 of aliphatic dicarboxylic acid.
0 mol%, glycol component is 1,9-nonanediol 2
0-60 mol% and tricyclodecane dialkanol 2
0 to 60 mol% and 1 to 10 with respect to all acid components
A resin composition for a coating composition, which is obtained by blending an alkyl etherified formaldehyde with a copolyester composed of 1 to 10 mol% of a polyol having a valency of 3 or more based on mol% of a polycarboxylic acid having a valency of 3 or more is there.

In the polyester resin of the present invention, the aromatic dicarboxylic acid is contained in an amount of 70 to 100 mol% based on all acid components.
As aromatic dicarboxylic acids to be blended and mainly used, isophthalic acid, terephthalic acid, phthalic acid, diphenyl-
m, m'-dicarboxylic acid, diphenylmethane-m, m '
-Dicarboxylic acid, diphenyl-P, P'-dicarboxylic acid, diphenylmethane-p, p'-dicarboxylic acid, 2,
2'-bis (4-carboxyphenyl) propane, naphthalene-1,4-dicarboxylic acid, naphthalene-2,7-
Dicarboxylic acid, diphenylether-p, p'-dicarboxylic acid, diphenylether-m, m'-dicarboxylic acid, diphenylsulfone-p, p'-dicarboxylic acid,
Diphenylsulfone-m, m′-dicarboxylic acid and the like are used, and these are used alone or in combination of two or more in the range of 70 to 100 mol%. When these aromatic dicarboxylic acids are less than 70 mol%, printability is improved. However, the blocking property is lowered, which is not preferable.

The aliphatic dicarboxylic acid is blended in an amount of 0 to 30 mol% with respect to the total acid component, and the aliphatic dicarboxylic acid mainly used is the aliphatic dicarboxylic acid represented by the following general formula, that is, Malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, 1,9-nonanedicarboxylic acid, 1,10-decanedicarboxylic acid, one or two
They are used in combination of 0 to 30 mol% or more, and if they exceed 30 mol%, printability and blocking property are not preferable. General formula: HOOC (CH ₂ ) n COOH 1 ≦ n ≦ 10

20 to 60 mol% of 1,9-nonanediol as a main glycol component of the polyester resin of the present invention
And 20 to 60 mol% of tricyclodecane dialkanol. Examples of the tricyclodecane dialkanol mainly used include tricyclodecane dimethylol, tricyclodecane diethanol, tricyclodecane dipropanol, tricyclodecane dibutanol, and the like, and these may be used alone or in combination of 20 to 60 mol. Used in combination in the range of%.

Further, 1 to 10 mol% relative to the total acid component, and 1 to 10 mol% relative to the polycarboxylic acid having a molecular weight of 200 to 1000 and having a valence of 3 or more and / or the total alcohol component.
Is a trivalent or higher polyol having a molecular weight of 200 to 1000
Used in combination of two or more kinds,
When 1,9-nonanediol is less than 20 mol% or tricyclodecane dialkanol is more than 60 mol%, printability is deteriorated, and nonanediol is more than 60 mol% or tricyclodecane alkanol is less than 20 mol%. In that case, the blocking property is deteriorated, which is not preferable. Further, when the polycarboxylic acid and / or polyol having a valence of 3 or more is not used, the printability is deteriorated, and when it is used in an amount of 20 mol% or more, the retort property is deteriorated, which is not preferable.

Alkyl etherified aldehydes are preferably used as crosslinking agents in the polyester resin of the present invention.
Used in the range of 0% by weight. Alkyl etherified aldehydes include, for example, formaldehyde or paraformaldehyde alkylated with an alkyl alcohol having 1 to 4 carbon atoms such as methanol, ethanol, n-propanol, isopropanol, and n-butanol, and urea, N, N '. -Condensation products with ethylene urea, dicyandiamide, aminotriazine, and the like, specifically, methoxylated methylol urea, methoxylated methylol-N, N'-ethylene urea, methoxylated methylol melamine, methoxylated methylol benzoguanamine, butoxylated There are methylol melamine and butoxylated methylol benzoguanamine, which can be used alone or in combination. Further, when the present cross-linking agent is not used, blocking property is deteriorated, and when it exceeds 50% by weight, retort property is deteriorated, which is not preferable.

The polyester resin of the present invention is preferably prepared by mixing a raw material and a polymerization catalyst in a stainless steel autoclave equipped with a stirrer, a thermometer and a partial reflux type cooler and synthesizing them by a known method. Butyl titanate, zinc oxide and / or antimony oxide are used.

The reduced viscosity of the polyester resin of the present invention is 0.3 or more, preferably 0.4 or more. When the reduced viscosity is less than 0.3, the printability and blocking property are significantly deteriorated, which is not preferable.

The polyester resin of the present invention has a glass transition temperature of 35 ° C. or higher. If the glass transition temperature is lower than 35 ° C., the blocking property is deteriorated, which is not preferable.

The polyester resin of the present invention has a molecular weight of 10
It is 000 to 20,000. If the molecular weight is less than 10,000, the blocking property is reduced, and if it is 20,000 or more, the retort property is reduced.

The polyester resin of the present invention is generally used in the form of being dissolved in an organic solvent. Examples of the organic solvent include toluene, xylene, Solvesso # 10.
0, aromatic hydrocarbons such as Solvesso # 150, ketone solvents such as methyl ethyl ketone, methyl isobutyl ketone and cyclohexanone, ethyl acetate, isopropyl acetate,
Solubility, evaporation rate, and cost among known solvents such as ester solvents such as n-butyl acetate, isobutyl acetate, and amyl acetate, ethers such as butyl cellosolve acetate, ethyl carbitol acetate, ethyl cellosolve acetate, and ester solvents. Can be arbitrarily selected in.

In the polyester resin of the present invention, depending on the use and purpose, for example, white pigment such as titanium dioxide, zinc white, yellow lead such as carbon black, pine smoke, graphite, light lead yellow lead, red lead yellow lead, zinc yellow, etc. Yellow pigments, red pigments such as vermilion and red iron oxide, blue pigments such as navy blue and cobalt blue, green pigments such as chrome green and green earth, iron oxide yellow, Mars yellow, iron oxide pigments such as iron oxide black, calcium carbonate, sulfuric acid Extender pigments such as barium, clay, alumina and talc, azo organic pigments such as Hansa Yellow 10G and toluidine red, phthalocyanine organic pigments such as phthalocyanine blue B and phthalocyanine green, and metal powders such as silver powder, copper powder and gold powder. Pigments, glass beads, glass powder, glass flakes and the like can be added.

As the coating method of the coating material comprising the polyester resin of the present invention, known coating methods such as spraying, brush coating, roll coating, flow coating and dipping can be used. The concentration used is a usual concentration according to these coating methods, for example, 10 to 60% by weight. The coating thickness is usually 5 to 30 μm (dry coating standard).

The polyester resin for paint of the present invention can be used as a resin for paint on the surface of metal materials such as cans, vehicles and machines, or paper.

[0021]

EXAMPLES The following examples will be given to more specifically describe the present invention, but of course the present invention is not limited to the examples. In the examples, "parts" means "parts by weight", and "%" means "% by weight". Each measurement item was performed according to the following method. (1) Reduced viscosity ηSP / C (dl / g) 0.10 g of polyester resin is converted into phenol / 1,1,
It was dissolved in a mixed solvent of 2,2, -tetrachloroethane (weight ratio: 6/4) of 25 cc and measured at 30 ° C. (2) Glass transition temperature It was measured at a temperature rising rate of 20 ° C./min using a differential scanning calorimeter (DSC). As the sample, 5 mg of the sample was put in an aluminum pressing lid type container and crimped for use.

(3) Printability 100 parts by weight of a polyester resin is mixed with 2 parts of methyl ethyl ketone.
It is dissolved in a mixed solvent of 00 parts by weight and 200 parts by weight of toluene, and the solution is dried to a film thickness of 10 μm.
50 mm x 70 mm x 0.8 mm mild steel plate (JIS G
3141) was applied using a bar coater, dried for 30 minutes and then dried at 150 ° C. for 4 minutes to obtain a test piece. The printed test piece was observed with a 10 times magnifying glass to determine the presence or absence of bleeding or aggregation of the ink layer. The criteria for judgment were as follows. ○: No abnormality. Δ: There is some bleeding from the ink layer. X: There is bleeding from the ink layer.

(4) Blocking property 100 g / cm of high-quality paper on coated steel sheet of polyester resin
Adhesion was made at ² and left for 24 hours, and then the presence or absence of blocking was determined. The criteria for judgment were as follows. ○: No abnormality. Δ: There is some blocking. X: There is blocking.

(5) Retortability A coated steel sheet of polyester resin is placed in boiling distilled water (130
The mixture was allowed to stand for 1 hour at (° C.) and the occurrence of blisters and whitening were visually evaluated. The criteria for judgment were as follows. ◯: No blister or whitening. B: Some whitening. X: There is a blister and whitening. (6) Composition analysis It was analyzed by NMR and the like.

Polyester Resin Synthesis Example (A) A stainless steel autoclave equipped with a stirrer, a thermometer and a partial reflux type cooler was used to prepare 246 parts of dimethyl terephthalate and 246 parts of dimethyl isophthalate.
-Nonanediol (254 parts), tricyclodecane dimethylol (311 parts) and tetrabutyl titanate (0.3 parts) as a polymerization catalyst were charged, and after transesterification at 180 to 230 ° C for 5 hours, 96 parts of sebacic acid and trimellitic anhydride. 31 parts of acid was charged and a dehydration condensation reaction was carried out at 220 to 230 ° C. for 2 hours. Next, the reaction system was depressurized to 5 mmHg over 30 minutes, and the temperature was raised to 250 ° C during this period.
Furthermore, the polycondensation reaction was performed for 30 minutes at 250 mm and 0.3 mmHg. The polyester resin obtained was yellow and transparent and had a reduced viscosity of 0.45 dl / g. Differential scanning calorimeter N
The glass transition temperature is 45 ° C., and the resin composition is terephthalic acid / isophthalic acid / sebacic acid / trimellitic acid // 1,9-nonanediol / tricyclodecane dimethylol = (40/40/15/5) by MR analysis. // 50/5
0) (molar ratio).

Comparative Synthesis Examples (B) to (F) Polyester resins shown in Table 1 were synthesized by the same method using the same reaction apparatus as in Synthesis Example (A). Synthesis example (A)
The reduced viscosity and glass transition temperature of the polyester resin obtained in the same manner as above were measured, and the composition was analyzed by NMR or the like. The results are shown in Table 1 below. Each component in the table indicates the number of moles.

Example 1 100 parts of the polyester resin obtained in Synthesis Example (A) was dissolved in a mixed solvent of 200 parts by weight of methyl ethyl ketone and 200 parts by weight of toluene, and methyl etherified methylol melamine (trade name: Cymel 303, Mitsui Cyanamid ( stock)
10 parts were added to obtain a coating agent (1). 150
The coating agent (1) was coated on a mild steel plate (mm × 70 mm × 0.8 mm) with an applicator to a film thickness of 10 μm, and air-dried for 30 minutes.
A test piece was obtained by drying at 4 ° C. for 4 minutes. A predetermined test was performed on the obtained test piece. The test results are shown in Table 2.

Example 2 100 parts of the polyester resin obtained in Synthesis Example (A) was dissolved in a mixed solvent of 200 parts by weight of methyl ethyl ketone and 200 parts by weight of toluene to obtain a coating agent (2). Each test was conducted in the same manner as in Example 1 using this coating agent. The test results are shown in Table 2.

Example 3 Polyester resins (B) to (F) in the same manner as in Example 1.
To obtain coating agents (3) to (8). Each test was conducted in the same manner as in Example 1. The test results are shown in Table 2.

[0030]

[Table 1]

[0031]

[Table 2]

[0032]

The polyester resin of the present invention is mainly composed of aromatic dicarboxylic acid, aliphatic dicarboxylic acid, 1,9-nonanediol as a glycol component, tricyclodecane dimethylol, a polycarboxylic acid having a valence of 3 or more as a branching agent, and (1) Adhesiveness to metal and film is good because of using polyol ether and / or alkyl etherified formaldehyde as a cross-linking agent. (2) It has excellent printability and can be used for can coating. (3) No blocking occurs. (4) It has good retort properties and has sufficient resistance to retort sterilization, which tends to be a problem in can coating. It is effective as a coating agent for can paints, various metals, papers, etc.

Claims (1)

[Claims] 1. An aromatic dicarboxylic acid having an acid component of 70 to 10
0 mol%, aliphatic dicarboxylic acid 0 to 30 mol%, glycol component is 1,9-nonanediol 20 to 60 mol% and tricyclodecane dialkanol 20 to 60 mol%
Alkyl ether in a copolymerized polyester containing 1 to 10 mol% of trivalent or higher polycarboxylic acid based on the total acid component and / or 1 to 10 mol% of trivalent or higher polyol relative to the total alcohol component. A resin composition for a coating composition containing a compounded formaldehyde.