JPS63122765A - Alkyd resin composition for coating - Google Patents

Abstract

PURPOSE:To provide the titled composition composed of a specific oil-modified alkyd resin and a crosslinking agent, having excellent storage stability and capable of giving a coating film having excellent water-resistance, weather- resistance, gloss, etc. CONSTITUTION:The objective composition can be produced by compounding (A) an oil-modified alkyd resin having an oil length of 18-50%, a hydroxyl value of 70-200 and a number-average molecular weight of preferably 2,000-20,000 and obtained by the esterification reaction of (i) an ester- interchange reaction product of an oil component (e.g. linseed oil) and a dihydric alcohol (e.g. ethylene glycol), (ii) a polybasic acid (e.g. phthalic anhydride) and (iii) a polyhydric alcohol (e.g. ethylene glycol, pentaerythritol, etc.) and (B) a crosslinking agent (e.g. aminoplast compound, polyvalent isocyanate compound, etc.) at a weight ratio of preferably 95:5-60:40.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to an alkyd resin composition for paint.

<Prior Art> Oil-modified alkyd resin paints have been widely used since they are cheaper than other synthetic resin paints.

By the way, oil-modified alkyd resins used in oil-modified alkyd resin-based paints are usually produced by subjecting an oil component to a transesterification reaction with a trihydric or higher polyhydric alcohol, and then transesterifying the transesterification product with a polybasic acid and a dihydric alcohol. It was produced by subjecting the above polyhydric alcohols to a varnish-forming reaction.

<Problems to be Solved by the Invention> The oil-modified alkyd resin paint, which is mainly composed of an oil-modified alkyd resin obtained by the above method, has various coating properties to a certain extent, but has poor water resistance. , weather resistance, gloss, etc., and the storage stability of the paint also had problems such as thickening during storage.

In view of the current situation, the present inventors have made extensive studies to solve the above-mentioned problems, and as a result, have discovered an alkyd resin composition for paints that solves or improves the above-mentioned problems, and have arrived at the present invention. It is.

Means for Solving the Problems> That is, the present invention provides (i) an esterification reaction of (a) a transesterification product of an oil component and a dihydric alcohol, and (c) an esterification reaction of a polybasic acid and (c) a polyhydric alcohol. I finally got it. The present invention relates to an alkyd resin composition for paint, comprising: an oil-modified alkyd resin having an oil length of 18 to 50% and a hydroxyl value of 70 to 200; (ii) a crosslinking agent;

The present inventors have discovered that when an oil component and a polyhydric alcohol are subjected to a transesterification reaction, a paint whose main component is an oil-modified alkyd resin obtained by using a dihydric alcohol as the polyhydric alcohol unexpectedly It was discovered that the storage stability of the paint is better than that of conventional oil-modified alkyd resin paints, and the paint film is superior in water resistance, weather resistance, gloss, etc., and this led to the present invention.

As the oil component used in the present invention, ordinary oil components conventionally used in oil-modified alkyd resins for paints can be used, and specifically, linseed oil, safflower oil, sunflower oil, soybean oil, Typical examples include cottonseed oil, rice sugar oil, rapeseed oil, coconut oil, palm oil, and palm kernel oil.

Typical dihydric alcohols used in the transesterification reaction include ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol, neopentyl glycol, 1.5-pencundiol, and 1.6-hexanediol. It will be done.

Typical polybasic acids used in the esterification reaction include phthalic anhydride, isophthalic acid, terephthalic acid, adipic acid, maleic anhydride, fumaric acid, trimellitic acid, and sebacic acid. Depending on the situation, a monobasic acid such as benzoic acid or tert-butylbenzoic acid may also be used in combination.

Polyhydric alcohols used in esterification reactions include:
Typical examples include polyhydric alcohols having a valence of two or more, specifically the above-mentioned dihydric alcohols, pentaerythritol, glycerin, trimethylolpropane, trimethylolethane, and the like.

The production of oil-modified alkyd resin involves mixing 1 mole of oil component and about 2 to 2.5 moles of dihydric alcohol with lead naphthenate, lead formate,
In the presence of a lead compound such as litharge, a transesterification catalyst such as lithium naphthenate, at a temperature of about 180 to 260°C, about 1
Allow transesterification reaction for ~3 hours, then add polybasic acid, polyhydric alcohol, and if necessary modifying components such as phenol resin and epoxy resin, and heat at approximately 180 to 240°C until the acid value reaches approximately 4 to 12. Obtained by reaction.

Oil-modified alkyd resin has an oil length of 18-50% and a hydroxyl value of 70.
~200 is appropriate. If the oil length is smaller than the above range, the resulting coating film will lack gloss, while if it is longer, the weather resistance and storage stability of the paint will deteriorate, which is not preferable.

On the other hand, if the hydroxyl value is smaller than the above range, the crosslinking density with the crosslinking agent will be insufficient, resulting in poor water resistance, weather resistance, etc. of the resulting coating film, and conversely, if it is too large, the water resistance, weather resistance, etc. This is not preferable because it worsens the condition.

The number average molecular weight of the oil-modified alkyd resin is approximately 2,000 to 2.
0. OOO is appropriate; if it is smaller than the above range, color separation tends to occur and water resistance tends to deteriorate,
On the other hand, if it is too large, the viscosity of the paint will increase, and painting workability will tend to deteriorate.

As the crosslinking agent, aminoplast compounds, polyvalent incyanate compounds, etc. can be used.

The aminoplast compound is a condensation product of an amino compound such as melamine, urea, benzoguanamine, or acetoguanamine and an aldehyde compound, or a compound obtained by further etherifying the condensation product with an alcohol such as butanol. When an aminoplast compound is used, a resin composition for molding paint that can be cured by baking can be obtained by mixing it with an oil-modified alkyd resin in a predetermined ratio.

Mixing ratio of oil-modified alkyd resin and aminoplast compound (
(weight basis) is within the range of (95:5 to 60:40), allowing the original resin properties to be exhibited. Examples of polyvalent isocyanate compounds include aliphatic, alicyclic, or aromatic diisocyanates such as hexamethylene diisocyanate, tetramethylene diisocyanate, inphorone diisocyanate, hydrogenated diphenyl diisocyanate, hydrogenated xylylene diisocyanate, and tolylene diisocyanate; Typical examples include biuret forms, dimers, trimers, or reaction products of excess amounts of these isocyanate compounds with low-molecular-weight polyols such as ethylene glycol, glycerin, trimethylolpropane, and pentaerythritol. . By mixing these polyvalent incyanate compounds with an oil-modified alkyd resin in a predetermined ratio, a two-component coating resin composition that can be cured even at room temperature is obtained.

In addition, the polyvalent incyanate compound may be phenols,
Blocked isocyanate compounds masked with masking agents such as alcohols, oximes, lactams, amines, amides, etc. can also be used, and in this case, a one-component type that can be cured by baking by mixing with an oil-modified alkyd resin in a predetermined ratio. It becomes a resin composition for paint.

The mixing ratio of the oil-modified alkyd resin and the polyvalent incyanate compound curing agent component is determined by the ratio of the incyanate groups of the incyanate compound to the hydroxyl groups of the oil-modified alkyd resin (NC○
10H) is (0.5 to 1.5/1), particularly preferably 0.8 to 1.2/1),
Within this range, it becomes possible to exhibit the original resin properties.

The composition comprising the oil-modified alkyd resin and crosslinking agent of the present invention is made into a paint by adding an organic solvent and, if necessary, various pigments and various additives.

Examples of organic solvents include hydrocarbons such as xylene and toluene, esters such as ethyl acetate and butyl acetate, ketones such as methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone, and ketones such as ethyl acetoacetate, butyl acetoacetate, and acetylacetone. - Enol-type tautomeric compounds, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether acetate, mineral spirits, etc.

Examples of the pigment include various coloring pigments such as titanium oxide, zinc white, ultramarine, and carbon black, various extender pigments, and various antirust pigments.

As additives, various additives such as thickeners, stabilizers, pigment dispersants, and ultraviolet absorbers are used as necessary.

The resin composition of the present invention is made into a paint by blending the above-mentioned components in normal proportions, and the resulting paint is applied to a film thickness of about 20 to 200 μm by means of spraying, rollers, spacing, etc. Ru.

In addition, when using an aminoblast compound or a blocked isocyanate compound as a crosslinking agent, the drying method is as follows:
Usually, it is appropriate to bake at 120 to 180°C for 15 to 30 minutes, and when a polyvalent isocyanate compound having free isocyanate groups is used, it is forcedly dried at room temperature or at a temperature of 100°C or lower.

<Effects of the Invention> According to the present invention, a paint whose main component is an oil-modified alkyd resin obtained by using a dihydric alcohol as an alcohol component to undergo a transesterification reaction with an oil component is a paint having a trivalent or higher valence as the alcohol component. It has better storage stability than conventional products using polyhydric alcohols, and the resulting coating film has excellent water resistance, weather resistance, gloss, etc.

Hereinafter, the present invention will be explained in more detail with reference to Examples. In the examples, "parts" and "%" are expressed on a weight basis.

Example 1 20.0 g of soybean oil was placed in a reactor equipped with dehydration and nitrogen reflux equipment.
15.0 parts of neopentyl glycol and 0.01 part of lead naphthenate, and while stirring, under nitrogen reflux,
Heat for 90 minutes while raising the temperature to 20℃, and then heat for 22 minutes.
The reaction was allowed to proceed for 30 minutes while maintaining the temperature at 0°C. 1 part of the obtained transesterification product was added to 2 parts of methanol, and after confirming complete dissolution (transparent), it was cooled, and then 24.0 parts of trimethylolpropane and 46.6 parts of phthalic anhydride were added. Heat again for 3 hours while raising the temperature to 220℃,
Further, the reaction was carried out at 220°C until the acid value reached 7, and after cooling, 66.7 parts of xylene was added, the oil length was 20%, and the hydroxyl value was 1.
Ten oil-modified alkyd resin faces were prepared.

Examples 2 to 6 and Comparative Examples 1 to 8 Oil-modified alkyd resin faces were prepared in the same manner as in Example 1 using the component ratios shown in Table 1.

Oil-modified alkyd resin face and melamine resin face obtained in Examples 1 to 6 and Comparative Examples 1 to 8 [“Melan 22”
(Product name manufactured by Hitachi Chemical Co., Ltd.); solid content 60%] and (7
25 parts of titanium white, 10 parts of xylene, and 10 parts of n-butanol were added to 60 parts of the mixed face consisting of :3), and the mixture was kneaded and dispersed to a thickness of 10 μm using the tube gauge A method to obtain a test paint. These paints were spray-painted on a mild steel plate with a thickness of 0.8 cm.
Baking at 0° C. for 20 minutes formed a coating film with a thickness of about 35 μm.

The storage stability of the paint thus obtained and the water resistance, hardness, gloss, weather resistance, and impact resistance of the paint film were tested, and the results are shown in the lower column of Table 1.

The test method was as follows.

Storage stability test: paint viscosity 100 seconds/FC#4 (20 seconds)
The viscosity was measured after the test paint was placed in a glass bottle and stored in a thermostat at 50°C for 2 weeks.

○: Viscosity 150 seconds or less, △: Viscosity 151 to 250 seconds, ×: Viscosity 251 seconds or more Water resistance test: A painted test plate was immersed in water at 50°C for 48 hours, and after 1 hour had elapsed after taking it out, a burr test ( (based on JIS K5400 6.15).

Hardness test: JIS K5400 6
．． Based on 14.

Gloss test: JIS K5400 6
．． Based on 7.

Weatherability test: Gloss retention after 500 hours using a carbon arc weatherometer.

0280% or more, Δ: 60 to 80%, X: 60% or less Impact resistance test: DuPont test (172 inch steel ball, 1 kg).

As is clear from Table 1, the storage stability of the paint of the present invention,
The coating performance was excellent. On the other hand, it is an oil-modified alkyd resin that uses a trivalent or higher polyhydric alcohol as the polyhydric alcohol used in the transesterification reaction. The paints of Comparative Examples 1 to 4 had poor storage stability, and the water resistance, weather resistance, impact resistance, etc. of the coating films were poor. Furthermore, the paint of Comparative Example 5, which was an oil-modified alkyd resin with a small oil length, had low gloss and poor weather resistance and impact resistance. Furthermore, the paint of Comparative Example 6, which was an oil-modified alkyd resin with a large oil length, had poor weather resistance and impact resistance. Furthermore, the paints of Comparative Examples 7 and 8, which were oil-modified alkyd resins with a high hydroxyl value and oil-modified alkyd resins with a low hydroxyl value, had poor water resistance, weather resistance, and the like.

Claims (2)

[Claims] (1) An oil with a length of 18 to 50% and a hydroxyl group obtained by esterifying (a) a transesterification product of an oil component and a dihydric alcohol, (b) a polybasic acid, and (c) a polyhydric alcohol. an oil-modified alkyd resin with a value of 70 to 200, (2) a crosslinking agent; An alkyd resin composition for paints consisting of: