Urethane curing catalyst aluminum chelate

Abstract

To provide a catalyst that exhibits adhesion of a cured urethane product to a metal substrate.SOLUTION: By using an aluminum chelate compound having a specific structure, for example such as ethyl acetoacetate aluminum diisopropylate, an aluminum chelate that acts as a catalyst or an aluminum chelate incorporated into the structure of the urethane resin reacts with hydroxyl groups on the surface of a metal substrate to form covalent bonds, thereby acting as a binder between the metal substrate and urethane and exhibiting adhesion.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to an aluminum chelate urethane curing catalyst. [Background technology]

[0002] Urethane resins are widely used in paints, printing inks, adhesives, etc., because of their excellent toughness, chemical resistance, adhesion to substrates, abrasion resistance, gloss, etc. In particular, room temperature curing urethane resins exhibit their excellent properties by combining a polyol compound as the base agent with a multifunctional isocyanate compound as the curing agent, and are used in many application fields. In the use of such urethane resins, catalysts are generally used to promote the reaction speed and performance improvement. As conventional catalysts, organotin compounds, amine compounds, and metal chelate compounds have been widely used. Although organotin compounds and amine compounds are widely used catalysts, they have limitations in their adhesion, and a method called primer treatment is widely adopted to improve the adhesion of urethane cured products to metal substrates. (See Patent Document 1) This method increases the number of work steps and may reduce production efficiency. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 11-124501 Summary of the Invention [Problem to be solved by the invention]

[0004] The present invention provides an aluminum chelate that exhibits adhesion of a cured urethane product to a metal substrate. [Means for solving the problem]

[0005] As a result of extensive research, the present inventors have discovered that an aluminum chelate having a specific structure exhibits adhesion of a cured urethane material to a metal substrate even without a primer treatment.

[0006] That is, the present invention is as follows. (1) It is an aluminum chelate compound represented by the general formula (I). [ka] (I) (In the formula, R1 to R4 represent an alkyl group, an alkenyl group, or an aromatic group having 1 to 30 carbon atoms.) (2) In (1), R1 and R2 are isopropyl groups, R3 is an ethyl group, and R4 is a methyl group.

[0007] The present invention further provides a method for producing a urethane resin, which comprises reacting a polyisocyanate compound with a polyol compound in the presence of the above-mentioned aluminum chelate urethane curing catalyst. Effect of the Invention

[0008] The aluminum chelate of the present invention can be used to produce a cured urethane product that exhibits adhesion to metal substrates without the use of a primer. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] The urethane curing catalyst aluminum chelate of the present invention is represented by the general formula (I). [ka] (I) (In the formula, R1 to R4 represent an alkyl group, an alkenyl group, or an aromatic group having 1 to 30 carbon atoms.)

[0010] In the general formula (I), R1 to R4 are preferably an alkyl group, an alkenyl group or an aromatic group having 1 to 30 carbon atoms, and more preferably R1 and R2 are isopropyl groups, R3 is an ethyl group, and R4 is a methyl group.

[0011] An example of a commercially available product is ALCH (ethyl acetoacetate aluminum diisopropylate) manufactured by Kawaken Fine Chemicals Co., Ltd.

[0012] In the general formula (A), when any of R1 to R4 is hydrogen, the urethane resin may not be cured due to the deactivation of the catalytic effect of the chelate. In the formula, R1 to R4 are preferably an alcohol compound represented by an alkyl group, alkenyl group, or aromatic group having 1 to 30 carbon atoms. If the carbon number is small, the compound is likely to solidify and the dispersibility in the resin is reduced, and if the carbon number is large, the melting point is high and it becomes difficult to synthesize aluminum alcoholate, so the carbon number is more preferably 3 to 18. Specific examples include methanol, ethanol, n-propanol, 2-propanol, n-butanol, isobutyl alcohol, sec-butyl alcohol, tert-butyl alcohol, 1-hexanol, lauryl alcohol, myristyl alcohol, stearyl alcohol, oleyl alcohol, behenyl alcohol, 1-tetracosanol, cyclohexanol, phenol, cresol, and quinolinol. If the carbon number of any of R1 to R4 exceeds 30, the net amount of Al, which is the central metal of the chelate, is reduced, which reduces the reactivity and may result in poor adhesion.

[0013] The principle by which the aluminum chelate urethane curing catalyst of the present invention exerts adhesion to metal substrates is believed to be as follows: It is speculated that the aluminum chelate that acts as a catalyst or the aluminum chelate incorporated into the structure of the urethane resin reacts with hydroxyl groups on the surface of the metal substrate to form covalent bonds, thereby acting as a binder between the metal substrate and the urethane and exerting adhesion.

[0014] The "urethane curing catalyst" in the present invention functions as a reaction catalyst between a polyisocyanate compound and a polyol compound.

[0015] The term "polyisocyanate compound" in the present invention refers to any compound having an isocyanate group in the molecule.

[0016] In the present invention, the term "polyol compound" refers to all compounds having two or more hydroxyl groups in the molecule.

[0017] The amount of the urethane curing catalyst used in the urethane composition of the present invention is not particularly limited, but the amount of the urethane curing catalyst used in the present invention relative to the entire urethane composition, i.e., the amount of the urethane curing catalyst used / the amount of the urethane composition used, is preferably 0.1 to 10 mass%, more preferably 0.5 to 5.0 mass%, and particularly preferably 1.0 to 3.0 mass%. If the amount is less than this ratio, the catalyst may not be active and may cause poor curing, and if the amount is more than this ratio, the catalyst may precipitate, causing curing inhibition.

[0018] The urethane curing catalyst aluminum chelate of the present invention can be used in urethane resin products such as paints, adhesives, flexible and rigid foams, elastomers, sealing materials, and civil engineering and construction materials. EXAMPLES

[0019] The present invention will be specifically described below with reference to examples, although the present invention is not limited to these examples.

[0020] Example 1 According to Table 1, the functional group molar ratio (NCO / OH) of the polyisocyanate compound and the polyol compound was 1.0, and 1.0 wt% of the catalyst ALCH (Kawaken Fine Chemical Co., Ltd.) was added, and the mixture was thoroughly stirred with a planetary centrifugal mixer (Thinky Corporation). The resulting paint was applied to degreased SUS316 (Taiyu Kizai Co., Ltd., cold-rolled stainless steel plate) with a bar coater (As One Corporation) to a dry film thickness of 50 μm, and the plate was left to harden at 25°C for 5 days to prepare a test plate.

[0021] (Examples 2 to 10) According to Table 1, test panels for Examples 2 to 10 were prepared in the same manner as in Example 1.

[0022] (Comparative Examples 1 to 7) According to Table 2, test plates for Comparative Examples 1 to 7 were prepared in the same manner as in Example 1.

[0023] (Substrate adhesion) The obtained test pieces were subjected to a cross-cut test for adhesion according to JIS K5600-5-6. 100 squares of 2 mm width were made on the coating film with a cutter knife, and then Cellotape (registered trademark) manufactured by Nichiban Co., Ltd. was attached to the squares and pressed with a finger, and the Cellotape (registered trademark) was quickly peeled off and evaluated. The results are shown in Tables 1 and 2. Evaluation was performed according to the following evaluation criteria.

[0024] (Evaluation Criteria) ◎: The edges of the cuts are completely smooth, and there is no peeling of the paint film on any of the grid holes. ◯: There is small peeling of the coating at the intersections of the cuts, but the affected area in the cross-cuts does not clearly exceed 5%. ×: Large peeling of the coating has occurred partially or completely along the edges of the cuts, and / or there is partial or complete peeling of the coating in several places, with the cross-cut area clearly exceeding 5% affected.

[0025] Examples 1 to 10 [Table 1]

[0026] Comparative Examples 1 to 7 [Table 2]

[0027] The raw materials and substrates used in the examples and comparative examples in Tables 1 and 2 are as follows. *1: Takenate (registered trademark) D-103H (TMP Adduct TDI), manufactured by Mitsui Chemicals, Inc. *2: Takenate (registered trademark) D-160N (TMP Adduct TDI), manufactured by Mitsui Chemicals, Inc. *3: Takenate (registered trademark) D-170N (HDI isocyanurate), manufactured by Mitsui Chemicals, Inc. *4: ALCH (ethyl acetoacetate aluminum diisopropylate), manufactured by Kawaken Fine Chemical Co., Ltd. *5: Dibutyltin dilaurate, manufactured by Tokyo Chemical Industry Co., Ltd. *6: Aluminum chelate D (aluminum monoacetylacetonate bis(ethylacetoacetate)) manufactured by Kawaken Fine Chemical Co., Ltd. *7: Cold-rolled stainless steel plate manufactured by Taiyu Machinery Co., Ltd. *8: Aluminum plate (A1050P) manufactured by Taiyu Machinery Co., Ltd.

[0028] As is clear from Tables 1 and 2, the urethane coatings using the urethane curing catalyst of the present invention shown in Examples 1 to 10 were rated as ⊚ or ◯ for metal substrate adhesion. In contrast, Comparative Examples 1 to 4 not using the catalyst of the present invention were rated as ×, and adhesion was poor. Furthermore, when aluminum chelates with different ligands were used as catalysts as shown in Comparative Examples 5 to 7, sufficient curing activity was not shown.

Claims

1. A urethane curing catalyst aluminum chelate compound represented by the general formula (A). 【Chemistry 1】 (A) (In the formula R １ ~R ４ represents an alkyl group, an alkenyl group, or an aromatic group having 1 to 3 carbon atoms.

2. In claim 1, R １ and R ２ is an isopropyl group, R ３ is an ethyl group, R ４ A urethane curing catalyst aluminum chelate compound in which the methyl group is present.

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