JPS62112664A - Paint resin composition - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a resin composition for paints, and more particularly to a paint composition for metal plates, particularly a paint composition for iron making, which has improved coating performance.

2. Description of the Related Art Metal cans made of tin, steel, etc. are widely used as containers for packaging foods such as soft drinks and fish.

For packaging using these metal cans, for example, metal plates are rolled up and their ends are joined together, the bottom plate is then tightened and attached, the food is then filled, and the lid plate is tightened and attached. Things can be mentioned.

By the way, the inner surface of such metal cans is coated with a resin film to prevent rust and to prevent food from getting unpleasant odors, and the outer surface is coated with product markings to prevent rust. Painting is often done to improve the appearance. This type of coating is applied to metal plates before they are processed into cans. For example, to paint the outer surface of a metal can, for example, a white coating is applied to the metal plate directly or via an undercoat, then letters, designs, etc. are printed, and then a transparent overcoat is applied.

The paint used for painting metal cans has anti-blocking properties (paints do not stick to each other when stacked) because the painting process is carried out in an assembly line, and the painted metal plates are stacked one after another. In addition, since it is heated and dried, color retention (not yellowing due to heat) is required. In addition, the coating must be flexible enough to withstand processing when molded into a paint container, hard enough to prevent scratches when touched by utensils, and retort resistant after filling the metal container with food. Various performances are required, including the ability to withstand high-pressure, high-heat treatment (retort treatment) for sterilizing objects.

Conventionally, as a resin used in such a paint for metal cans, an esterified product of an epoxy resin and a semi-drying oil fatty acid or a drying oil fatty acid has been used. Paints containing this resin can be used as room temperature drying paints or as thermosetting paints (
It is widely used as a baking paint.

However, the coating film of this type of paint has poor curing properties,
Therefore, when used as an iron-making material, the drying properties of the paint film are poor, and when painted at normal speed, it is easy to cause buffing when stacked, and the hardness of the paint film is low, so the paint film There are other problems such as being easily scratched, and furthermore, the degree of hardening of the coating film is insufficient, resulting in insufficient retort resistance. These drawbacks can be solved by adding a metal dryer such as cobalt manganese octylate to promote air drying by the drying oil or semi-drying oil itself, or by using an amino resin such as melamine resin or a phenolic resin initial condensate. Attempts have been made to improve the hardness of the resin itself by supplementing it with curing through condensation reactions, or by modifying it with vinyl monomers such as styrene or acrylic monomers, thereby improving its drying properties and hardness. .

However, although these methods improve drying properties and coating film hardness, on the other hand, when using a metal dryer or amino resin, the coating film tends to turn yellow when drying (color retention is significantly impaired, Furthermore, those modified with styrene or acrylic monomers have markedly poor flexibility, and none of them are practically satisfactory.

Problems to be Solved by the Invention As mentioned above, conventional paints for iron making are difficult to dry when the epoxy resin modified with a semi-drying oil fatty acid or a drying oil fatty acid is cured only by its own hardening property. Furthermore, when using a catalyst such as a metal dryer or promoting curing with other resins such as amino resins, there are problems with color retention. In the case of denaturation, there is a problem with the flexibility of the coating film, and it has not been possible to fully satisfy various performances required as a steelmaking coating material.

Means for Solving the Problems In order to solve the above problems, the present invention aims to solve the above problems by reducing the iodine value to 1.
An unsaturated fatty acid-modified epoxy resin having an epoxy group modified with 20 or more unsaturated fatty acids, and 0.1 to 99.9 to 95 parts by weight of this unsaturated fatty acid modified epoxy resin.
The present invention provides a resin composition for coating material containing 5 parts by weight of phosphoric acid.

Next, the present invention will be explained in detail.

Examples of the epoxy resin having a free water M group used in the present invention include diglycidyl ether produced from epichlorohydrin and bisphenol A and having the following structure. In this formula, n≧1.

A diglycidyl ether prepared from epichlorohydrin and bisphenol F and having the following structure can also be used. In this formula, n≧1.

Furthermore, diglycidyl esters synthesized from polybasic acids and epichlorohydrin can also be used.

Specific examples of epoxy resins used in the present invention include Epicort 1007.1009.1010 (manufactured by Yuka Shell Epoxy Co., Ltd.), Evicron 7050.9050 (manufactured by Dainippon Ink Chemical Industry Co., Ltd.), AEl? -667,
-669 (manufactured by Asahi Kasei Co., Ltd., Araldai) 6097.6
099 (manufactured by Chino-Geigy) and other resins.

Iodine number 120 for modifying epoxy resin in the present invention
These unsaturated fatty acids include linoleic acid, lylunic acid, eleostearic acid, lycanic acid, dehydrated castor oil fatty acid, linseed oil fatty acid, tung oil fatty acid, oyster oil fatty acid, soybean oil fatty acid, safflower oil fatty acid, and castor oil fatty acid. , drying oil or semi-drying oil fatty acids such as tall oil fatty acids.

In order to produce the unsaturated fatty acid-modified epoxy resin in the present invention, it is preferable to use transesterification.

When utilizing this transesterification reaction, it is desirable to use lower alcohol esters of the unsaturated fatty acids, such as methyl alcohol and ethyl alcohol.

The transesterification reaction between the epoxy resin and the unsaturated fatty acid lower alcohol ester is preferably carried out in an amount of 25 to 50 parts by weight of the fatty acid ester based on 100 parts by weight of the epoxy resin. If the amount is less than 25 parts by weight, the resulting resin will not have good flexibility, and if it is more than 50 parts by weight, the hardness of the resulting resin coating will be poor.

The temperature of the above transesterification reaction is 160 to 240°C,
More preferably it is 180-210°C. In this case, it is preferable to use a transesterification catalyst in combination, and examples thereof include sodium alkoxide, lithium, sodium, and calcium acetic acid or fatty acid salts, and these are used in appropriate amounts. In addition, when the epoxy resin has a high molecular weight and a high melt viscosity, the above-mentioned transesterification reaction may be carried out in a non-reactive solvent such as an aromatic hydrocarbon or plain water.

The unsaturated fatty acid-modified epoxy resin thus obtained has a reactive epoxy group at the end of the molecule, and 99.9 to 95.0 parts by weight of the resin contains 0.1 to 5.0 parts of phosphoric acid.
Parts by weight of the paint were added under normal curing conditions, i.e. 160
It exhibits sufficient curability when heated at 190°C for 10 minutes. If the phosphoric acid content is less than 0.1, curing will be insufficient, and if it is more than 5.0, the curability will not be so good.

The curing mechanism is thought to be due to both the curing properties of unsaturated fatty acids and cross-linking of epoxy groups by phosphoric acid, but phosphoric acid does not turn yellow even when heated together with unsaturated fatty acids, and it is also due to the reaction of epoxy groups. Crosslinking can impart appropriate flexibility and hardness to the coating film, which is considered to be the reason why the composition of the present invention was able to impart excellent properties. Generally, epoxy groups react with acids, but phosphoric acid is thought to have an excellent effect on the reactivity.

The above-mentioned unsaturated fatty acid-modified epoxy resin of the present invention is used as a paint for various metal products and other vehicles, and has excellent film hardness, flexibility, and retention properties, especially as a clear paint for overcoating of iron making paints. Shows color properties and retort resistance. When used as a paint, other components, such as colorants, plasticizers, lubricants, and ultraviolet inhibitors, may be used in combination depending on the intended use.

Effects of the Invention As described above, the present invention can provide a coating containing an unsaturated fatty acid-modified epoxy resin with an iodine value of 120 or more; phosphoric acid is added thereto. This is supplemented by the reaction of epoxy groups, and as a result, color retention is impaired by using metal dryers or amino resins as in the past, or by modification with vinyl monomers, and due to lack of flexibility, for example, paints for iron making. This can be done without impairing the processing resistance of the coating film. In this way, it is possible to exhibit excellent performance not only in coating, but also in various resistances required during and after can processing, for example, as a paint for iron making.

Example Next, the present invention will be explained in detail.

Examples 1 to 3 use epoxy resins whose molecular weights increase successively.

Example 1 Solveso 150 was added to 11 four-way flasks equipped with a nitrogen inlet tube, thermometer, decanter, condenser, and stirring device.
(manufactured by Esso Standard Oil Co., Ltd.) and 120 parts of dehydrated castor oil fatty acid methyl ester (drying oil fatty acid ester manufactured by Soken Chemical Co., Ltd.) were charged, and the temperature was raised to 120°C.

Epikote 1004 while maintaining 110℃~120℃
After gradually adding 280 parts of (manufactured by Yuka Shell Epoxy Co., Ltd.), the temperature was raised to 200°C, and 0.32 parts of Catalyst N (lithium naphthenate; manufactured by Dainippon Ink Chemical Co., Ltd.) was added, and at the same temperature. The transesterification reaction was carried out after methanol was distilled off for 4 hours. The product was diluted with Solbeso 15072.8 parts and butyl cellosolve 192.8 parts, and the nonvolatile content was 49.5%, the viscosity (Gardner, hereinafter the same) V, and the acid value 0.
．． 3. A resin solution having an epoxy equivalent (hereinafter the same) of 3,940 was obtained.

This resin solution and phosphoric acid are 99.810.2 (solid content ratio)
and diluted with ethyl cellosolve to prepare a clear paint.

Example 2 Into the same reactor as in Example 1, 150,150 parts of Solveso and 97.5 parts of the dehydrated castor oil fatty acid methyl ester were charged, and the temperature was raised to 140°C. While maintaining the temperature at 130 to 140°C, 202.5 parts of Epicoat 1007 (manufactured by Yuka Shell Epoxy Co., Ltd.) was gradually added, and then the temperature was raised to 200°C. Thereafter, 24 parts of Catalyst N2O was added, and the transesterification reaction was carried out at the same temperature for 4 hours while distilling off methanol. The product was converted into butyl cellosolve 58.8
parts, diluted with 15081.6 parts of Solbeso, non-volatile content 49
．． 3. A resin solution having a viscosity of z11 parts of 0.4 and an epoxy equivalent of 12,100 was obtained.

This resin solution was also blended in the same manner as in Example 1 to prepare the clear paint of this example.

Example 3 10.6 parts of Solbeso 1502 and 105 parts of the dehydrated castor oil fatty acid methyl ester were charged into a reactor similar to that in Example 1, and the temperature was raised to 160°C. While maintaining the temperature at 150 to 160°C, 195 parts of Epicoat 1009 (manufactured by Yuka Shell Epoxy Co., Ltd.) was gradually added, and then the temperature was raised to 20°C. Add 24 parts of catalyst N O and heat at the same temperature.
The transesterification reaction was carried out while methanol was distilled off for a period of time. The product was diluted with 210.6 parts of butyl cellosolve to obtain a resin solution having a nonvolatile content of 39.4%, a viscosity of Y-Z, an acid value of 0.1, and an epoxy equivalent of 13,300.

This resin solution was also blended in the same manner as in Example 1 to prepare the clear paint of this example.

Next, a comparative example will be explained.

Comparative Example 1 uses no acid such as phosphoric acid, Comparative Example 2 uses an acid other than phosphoric acid, Comparative Example 3 uses a conventional drying oil-modified epoxy resin, and Comparative Example 4 uses a conventional drying oil-modified epoxy resin. Comparative Example 3 was made melamine-curable, and Comparative Example 5 was a drying oil-modified epoxy resin modified with styrene.

Comparative Example 1 A clear paint was prepared by diluting the resin solution obtained in Example 3 with ethyl cellosolve.

Comparative Example 2 The resin solution obtained in Example 3 and succinic acid were mixed at 99.0/
A clear paint was prepared by blending at a solid content ratio of 1.0 and diluting with ethyl cellosolve.

Comparative Example 3 (Resin that does not leave epoxy groups) Dehydrated castor oil fatty acid (manufactured by Soken Kagaku Co., Ltd.) was placed in the same reactor as in Example 1.
105 parts of Epicoat 1004, 195 parts of zirconium octylate, and 9.6 parts of Solbeso 100 (manufactured by Esso Standard Oil Co., Ltd.) were charged, and the temperature was raised to 240°C over 4 hours, and then kept at the same temperature for another 2 hours. An esterification reaction was performed. The product was diluted with 22.6 parts of Solbeso 150, 57.6 parts of butyl cellosolve, and the non-volatile content was 50.
．． A resin solution of 2%, viscosity T, and acid value 0.8 was obtained.

This resin solution was diluted with ethyl cellosolve to prepare a clear paint for this comparative example.

Comparative Example 4 Melan 35S (melamine resin manufactured by Hitachi Chemical Co., Ltd.) was blended with the resin solution of Comparative Example 1 at a ratio of 80/20 (solid content ratio) and diluted with ethyl cellosolve to prepare a clear paint of this comparative example. .

Comparative Example 5 Resin solution 648 of Comparative Example 1 was placed in 11 four-way flasks equipped with a nitrogen inlet tube, thermometer, condenser, and stirring device.
parts, Solbeso 15048.8 parts, butyl cellosolve 15
．． 2 parts and 20 parts of α-methylstyrene dimer as a chain transfer agent were added, and the temperature was raised to 140°C. At the same temperature, a mixture of 64 parts of styrene and 1.6 parts of di-t-butyl peroxide was added dropwise over a period of 1 hour, and 2 and 4 hours later, 0.8 parts of di-t-butyl peroxide was added. Added. The non-volatile content was further maintained at the same temperature for 2 hours to 49.
A resin solution with a viscosity of 7%, a viscosity of XY, and an acid value of 1.3 was obtained.

Add 99.810.2 cobalt octylate to this resin solution.
(solid content ratio) and diluted with butyl cellosolve to prepare a clear paint of this comparative example.

The paints obtained in Examples 1 to 3 and Comparative Examples 1 to 5 above were applied to a tin plate using a bar coater so that the dry coating amount was 45mg/100cnt, and then heated and dried at 180°C for 10 minutes to give a test piece. It was created.

Regarding the coating film performance of the test pieces obtained in this way, blocking resistance, glass transition temperature, impact resistance, bending resistance,
Retort resistance and color retention were investigated and the results shown in the table were obtained. In the table, ◎ indicates excellent, ○ indicates good, △ indicates slightly poor, and × indicates poor.

The various test methods are as follows.

Blocking resistance test pieces were cut into 13co+X13cm pieces and stacked together to give a weight of 2Kg/cn! , after heating under pressure at 50°C for 2 hours, 12
The specimens were left to cool under pressure for a period of time, then taken out, and it was visually determined whether the specimens were attached to each other.

The glass transition temperature T, ("C) was measured using the glass transition point penetration method and is shown as a measured value. This indicates the hardness and softness of the resin film.

Impact resistance: Ikg load was applied to a height of 50 at room temperature using a DuPont impact tester.
An impact was applied by dropping it from an oven, and the degree of damage to the coating film was visually determined.

A test piece of bending resistance of 4 cm x 5 cm was prepared and folded in half by hand.
This was bent using a DuPont impact tester special folding type tester at room temperature by dropping an IKg load from a height of 50 ann, and the length and condition of the crack in the coating film at the bent portion was visually determined.

The retort resistance test piece was placed in a retort pot and subjected to retort treatment at 130° C. for 30 minutes, and then the degree of damage to the coating film was visually determined.

The color retention test piece was additionally heated and dried at 190° C. for 10 minutes, and the degree of yellowing of the coating film was visually determined.

As is clear from the table, the example of the present invention showed excellent or good performance in all test items, but the comparative example did not show practically satisfactory performance in all test items. .

November 11, 1985

Claims (1)

[Claims] (1) An unsaturated fatty acid-modified epoxy resin having an epoxy group modified with an unsaturated fatty acid having an iodine value of 120 or more, and 0.1 to 5 parts by weight based on 99.9 to 95 parts by weight of this unsaturated fatty acid modified epoxy resin. A resin composition for paint, characterized in that it contains phosphoric acid in a proportion of .