JPS5938994B2 - Resin composition for paint - Google Patents

Description

[Detailed description of the invention] The present invention relates to a resin composition for paint.

Specifically, it is made by linking an initial polyester condensate derived from a saturated dibasic acid and a glycol via an epoxy compound containing at least two epoxy groups in one molecule, and a hydroxyl group as a crosslinkable functional group. The present invention relates to a resin composition for coating material containing a high molecular weight saturated polyester as a main component. BACKGROUND ART Conventionally, it is known to directly react a saturated dibasic acid and a glycol in one step to prepare a high molecular weight saturated polyester, and to apply the obtained polyester to applications such as paints, adhesives, and printing inks.

However, preparing the desired polyester through direct reaction requires a high-vacuum manufacturing equipment, resulting in expensive polyester. Several methods have been proposed to overcome this drawback. . For example, JP-A-5
According to the invention of No. 4-24998, a method is proposed in which a saturated dibasic acid and a glycol are reacted according to a known procedure to form an initial condensate, and the molecular weight is increased by adding a diisocyanate to this. . However, although this method is satisfactory in terms of molecular weight, it only yields polyester that has functional groups that contribute to the crosslinking reaction or are located at both ends of the molecule, and paints containing such polyester as the main component cannot be obtained. Even when a crosslinking agent was added to the composition, a sufficient amount of crosslinking reaction required to exhibit coating film performance did not occur. In the end, the drawback was that a coating film with excellent performance could not be obtained. As a result of repeated studies to overcome the above-mentioned drawbacks of the conventional method, the present inventors discovered that an initial polyester condensate derived using an acid component of a specific composition and at least two epoxy groups in one molecule. A high molecular weight saturated polyester having a hydroxyl group as a crosslinkable functional group can be obtained by reacting a specific amount of an epoxy compound including The present invention was completed by discovering the following.

The coating resin composition of the present invention has an aromatic dibasic acid of 80 to 2
(b)/(a)-0. An initial polyester condensate having an acid value of 5 to 20 is prepared by reacting at a molar ratio in the range of 9 to 1.1, and then the amount of epoxy groups is at least equal to the amount of carboxyl groups contained in the initial polyester condensate. An epoxy compound (c) having two epoxy groups in one molecule (hereinafter referred to as a diepoxy compound (c)) with the initial polyester condensate in such a ratio that

) is characterized in that it consists mainly of a high molecular weight saturated polyester obtained by reacting. Acid component used in preparing the initial polyester condensate (
A) is composed of 80 to 20 mol% of aromatic aromatic dibasic acid and 80 to 20 mol% of aliphatic saturated dibasic acid.

This usage ratio indicates a preferable range in terms of the physical properties of the rose coating film, such as flexibility, weather resistance, and chemical resistance.
For example, aromatic dibasic acid is 80 mol% of the acid component (a)
If this value is exceeded, a coating film exhibiting sufficient flexibility will not be obtained. Also, acid component (a) and aliphatic saturated glycol (b)
The molar ratio of (b)/(a) is in the range of -0.9 to 1.1, and if the ratio exceeds 1.1, the molecular weight of the initial polyester condensate will become extremely small, which is undesirable. On the other hand, if the ratio is less than 0.9, there is a drawback that it becomes difficult to control the acid value of the initial polyester condensate within the range of 5 to 20. The initial polyester condensate used in the present invention has an acid value in the range of 5 to 20.

If the acid value is less than 5, the amount of hydroxyl groups generated as crosslinkable functional groups will not be sufficient even if the diepoxy compound (c) is reacted, and the effects of using the diepoxy compound (c) cannot be expected. Moreover, if the acid value exceeds 20, a high molecular weight saturated polyester with a high content of crosslinkable functional groups will be obtained, and if such a polyester is used, a coating composition with well-balanced performance cannot be obtained. Examples of the aromatic dibasic acid used in preparing the initial polyester condensate include terephthalic acid, isophthalic acid, phthalic acid, phthalic anhydride, and lower alkyl esters of these acids, such as dimethyl terephthalate. , one type or two or more types can be used.

Examples of the aliphatic saturated dibasic acids include adipic acid, sebacic acid, azelaic acid, etc., and one type or two or more types can be used. Further, as the aliphatic saturated glycol (b), ethylene glycol, diethylene glycol,
Triethylene glycol, propylene glycol, dipropylene glycol, neopentyl glycol, butanediol, etc. can be mentioned, and one type or two or more types can be used. If necessary, a compound having a carboxyl group and a hydroxyl group in the molecule, such as paraoxybenzoic acid, can be used in combination with an acid component or a glycol component. The initial polyester condensate can be easily prepared according to conventionally known procedures. For example, a reactor may contain acid component (a) and aliphatic saturated glycol (
Prepare b) and heat at 160 to 240°C under an inert gas atmosphere.
It can be adjusted by carrying out a condensation reaction at a temperature of . In this case, the important thing is the amount of reactants to be used, and it is necessary to take sufficient care to satisfy the above formula.
If either is used in excess or too little, only an initial polyester condensate with difficulty in achieving the desired high molecular weight will be obtained. As the diepoxy compound (c) used in the present invention, various epoxy resins, particularly bisphenol type epoxy resins, can be effectively used.

This bisphenol type epoxy resin has the general formula (however,
In the formula, R is -H or -CH3, and A has 1 to 8 carbon atoms.
is an alkylene group, -S1 or -01, and n is 0 or an integer of 1 to 10.

), and the value of n in the above formula does not need to be a single value; the main component is the molecule represented by the value n=n1, and the value of n or n1-1. n! -2, town +1, n1+2
The molecular weight is usually indicated by a value such as . Typical examples of such bisphenol type epoxy resins that are generally commercially available include a product manufactured by Shell Co., Ltd. (product name: Epiate), a product manufactured by Tau Chemical Co., Ltd. (product name: DEN, Switzerland), and a product manufactured by Tau Chemical Company (product name: Examples include a product manufactured by Kuni Ciba Co., Ltd. (trade name: Araldite"), a product manufactured by Sumitomo Chemical Co., Ltd. (trade name: Sumie Epoxy), and a product manufactured by Dainichi Ink Chemical Co., Ltd. (trade name: Epicron"). The high molecular weight saturated polyester of the present invention is obtained by reacting an initial polyester condensate with a diepoxy compound (c).

The reaction between the two is Solbetsuso (hydrocarbon solvent manufactured by Etsuso)
It is preferable to carry out the reaction in a suitable solvent such as isoboron, etc., or the solvent can be used as part of the coating composition described below without being removed from the system after the reaction is completed. The coating composition of the present invention has the high molecular weight saturated polyester of the present invention as a main component, and may contain additives commonly used in this type of field, such as flow control agents and pigment dispersants, as necessary. I can do it.

Since the hydroxyl group of high molecular weight saturated polyester acts as a crosslinking functional group, paints containing compounds such as methylated melamine and polyfunctional isocyanates as crosslinking agents, and pigments as necessary, can be used as acid components. This product has better cross-linking reactivity than paints using saturated polyester obtained by the conventional method of reacting glycol in one step under high vacuum, and can be cured at low temperatures, giving a coating film with even better properties. It is. Hereinafter, the present invention will be explained in more detail with reference to Examples.

In addition, parts in the examples mean parts by weight unless otherwise specified. Example 1 In a reactor equipped with a stirrer, a condenser and a thermometer, 310 parts of terephthalic acid, 200 parts of isophthalic acid, and 160 parts of sebacic acid were added.
120 parts of ethylene glycol, 210 parts of neopentyl glycol, and 1 part of tetraisopropyl titanate, and the temperature was gradually raised from 160°C to 230°C.
The initial polyester condensate (hereinafter referred to as condensate I) having an acid value of 13.2 was obtained by reacting for a period of time.

) was obtained. 400 parts of condensate I
After dissolving in 100 parts of 5Cy/(manufactured by Etsuso Co., Ltd., aromatic hydrocarbon solvent), 18 parts of Epiclone 850'' (bisphenol epichlorohydrin type epoxy resin manufactured by Dainippon Ink Chemical Co., Ltd.) was added, and the mixture was heated at a temperature of 19°C. The mixture was reacted for 4 hours to obtain a solvent solution of a high molecular weight saturated polyester having a solid content of 80% and an acid value of 1.8.

This solvent solution was used as a paint resin composition (hereinafter referred to as Composition I "I"). Incidentally, as a result of measuring the condensate "" and composition [1] by GPC, the weight average molecular weights were 22,000 and 40,400, respectively.

A paint was prepared by blending 20 parts of Cymel 1 303'' (melamine resin manufactured by American Cyanamid Co., Ltd.), 0.3 parts of para-toluenesulfonic acid, and 100 parts of pigment (TiO2) into 100 parts of Composition 1 "I". The thus obtained paint was applied with a bar coater onto Bonderite #37 treated galvanized iron having a thickness of 0.3 mm, and then dried at a temperature of 250°C for 1 minute to form a paint film with a dry film thickness of approximately 15 microns. The properties of the coating film were as shown in Table 1.Example 2 400 parts of condensate ``I'' was mixed with Solbetuso 1501'1.
After dissolving in 00 parts.

35 parts of Epiclon-1850'' were added and reacted for 3 hours at a temperature of 170°C to obtain a solvent solution of high molecular weight saturated polyester with an acid value of 0.2.Then, this solvent solution was mixed into a coating resin composition (hereinafter referred to as Composition 1 (referred to as "composition 1"). A coating material was prepared in the same manner as in Example 1 except that composition "I" was used instead of composition "I", and then the coating film performance was measured.

The results were as shown in Table 1. Example 3 A reactor was charged with 425 parts of terephthalic acid, 140 parts of isophthalic acid, 125 parts of adipic acid, 90 parts of ethylene glycol, and 220 parts of propylene glycol, and the temperature was gradually raised from 160°C to 230°C and reacted for 12 hours. Acid value 1
0.6 initial polyester condensate (hereinafter referred to as condensate 1)
That's what it means.

) was dissolved in 100 parts of isoborone, 15 parts of Epiclon 850'' was added, and the mixture was reacted for 4 hours at a temperature of 19°C, resulting in a solid content of 80(:I).
) A solvent solution of a high molecular weight saturated polyester with an acid value of 2.5 was obtained.

This solvent solution was used as a coating resin composition (hereinafter referred to as "composition"). In Example 1, composition -
A paint was prepared in the same manner except that composition - "l" was used instead of "l".

The coating film performance was as shown in Table 1. Example 4
After dissolving 400 parts of condensate 1 in 100 parts of isoborone, 30 parts of Epiclon 850 was added and heated at 170°C.
The reaction was carried out at a temperature of 3 hours to obtain a solvent solution of a high molecular weight saturated polyester with an acid value of 0.5.

This solvent solution was used as a paint resin composition (hereinafter referred to as "composition 1"). In Example 1, the composition-
A paint was prepared in the same manner except that Composition 1 "" was used instead of "l".

The properties of the coating film were as shown in Table 1. Comparative example 1
Condensate one “l” is 17! The condensation reaction proceeded under the conditions of a vacuum degree of TmHg and a temperature of 240°C to obtain a comparative saturated polyester with an acid value of 1.8.

Using this polyester, a resin composition for a comparative paint (hereinafter referred to as "Comparative Composition I") was prepared according to the same procedure as in Example 1, and then a comparative paint was prepared. The coating film performance was as shown in Table 1. Comparative example
2 In Example 1, a resin composition for a comparative paint (hereinafter referred to as "comparative composition") was prepared in the same manner as in Example 1, except that the amount of Epiclon-850I (D used was 9 parts).

Claims (1)

[Claims] 1 Acid component (a) consisting of 80 to 20 mol% of aromatic dibasic acid and 20 to 80 mol% of aliphatic saturated dibasic acid and aliphatic saturated glycol (b) having 2 to 10 carbon atoms (b) )/
(a) = react at a molar ratio in the range of 0.9 to 1.1 to prepare an initial polyester condensate with an acid value of 5 to 20, and then A resin composition for coatings containing as a main component a high molecular weight saturated polyester obtained by reacting an initial polyester condensate with a compound (c) having two epoxy groups in one molecule in proportions such that the amounts are at least equal. thing.