JP2522856B2 - Primer composition - Google Patents

Description

TECHNICAL FIELD The present invention relates to a primer composition, and more particularly to a primer composition that is useful for improving the adhesion between a condensation type room temperature curable silicone elastomer and a coating metal. It is a thing.

(Prior Art) A condensation type room temperature curable silicone elastomer has good adhesiveness to various objects, adheres well to a metal surface, and also has a certain degree of adhesiveness to a coated metal, It is widely used as a sealing agent for construction.

(Problems to be solved by the invention) However, recently, as exterior wall materials for construction, those coated with fluororesin-based paint, urethane resin-based paint, acrylic resin-based paint, etc. are often used from the viewpoint of weather resistance and appearance. However, this condensation-type room-temperature-curable silicone elastomer does not show good adhesion to this type of coating metal, and this adhesion is due to the fact that conventionally known silanes or their co-adhesives are present on the surface of the coating metal. There is a drawback that the use of a primer containing a silicone resin, which is a hydrolyzed condensate, as a component does not improve.

(Means for Solving the Problems) The present invention relates to a primer composition capable of solving such disadvantages and drawbacks.
(OR ¹ ) ₄ (wherein R ¹ is an alkyl group having 1 to 8 carbon atoms) or a (co) partial hydrolysis product thereof, B) General formula Ti (OR ² ) ₄ (here R ² is an alkoxytitanium represented by an alkyl group having 1 to 8 carbon atoms or a (co) partial hydrolysis product thereof, C) the general formula R ³ COOR
⁴ (wherein R ³ and R ⁴ are the same or different and are unsubstituted or substituted monovalent hydrocarbon groups) and the reaction product of a carboxylic acid ester is used as a main agent.

That is, the present inventors have conducted various studies to develop a primer composition for improving the adhesion between a condensation type room temperature curable silicone elastomer and a coating metal. As a result, the primer composition has been used as a silicon alkoxide or an alkoxytitanium. It was found that, when composed of a three-component reaction product of carboxylic acid ester and carboxylic acid ester, this compound exhibits excellent properties as an adhesion improver between a condensation type room temperature curable silicone elastomer and a coating metal. The present invention has been completed by conducting research on the types of components, blending amounts, reaction methods, and the like.

 This will be described in more detail below.

(Function) The present invention relates to a primer composition for improving the adhesion between a condensation type room temperature curable silicone elastomer and a coating metal.

The primer composition of the present invention is obtained by reacting three components of A) a silicon alkoxide or a (co) partial hydrolysis product thereof, B) an alkoxytitanium or a (co) partial hydrolysis product thereof, and C) a carboxylic acid ester. The obtained product is used as the main agent.

The silicon alkoxide as component A) for producing this primer composition is a tetraalkoxy represented by the general formula Si (OR ¹ ) ₄ (I) (wherein R ¹ is an alkyl group having 1 to 8 carbon atoms). In silane, R ¹ is an alkyl group such as a methyl group, an ethyl group, a propyl group, and a butyl group, and is preferably tetramethoxysilane, tetraethoxysilane, or tetrapropoxysilane. May be partially hydrolyzed, and further, two or more kinds of these silanes may be partially hydrolyzed.

Further, the alkoxytitanium as the component B) for producing the primer composition of the present invention is represented by the general formula Ti (OR ² ) ₄ (II) (wherein R ² is an alkyl group having 1 to 8 carbon atoms). In the tetraalkoxy titanium, R ² is an alkyl group such as a methyl group, an ethyl group, a propyl group, and a butyl group, and is preferably tetramethoxy titanium, tetraethoxy titanium, or tetrapropoxy titanium. It may be a partially hydrolyzed version of these alkoxytitaniums, or a co-partially hydrolyzed version of two or more of these alkoxytitaniums.

Next, the carboxylic acid ester as the component C) for producing the primer composition of the present invention is represented by the general formula R ³ COOR ⁴ ... (III), and R ³ and R ⁴ are each independently a methyl group or an ethyl group. , Alkyl groups such as propyl group and butyl group, alkenyl groups such as vinyl group, allyl group and butenyl group, aryl groups such as phenyl group and tolyl group, aralkyl groups such as benzyl group and β-phenylethyl group, or these groups Selected from a chloromethyl group, a trifluoropropyl group, a cyanoethyl group, etc., in which some or all of the hydrogen atoms bonded to the carbon atoms are substituted with a halogen atom, a cyano group, etc., usually having 1 to 10 carbon atoms, preferably Is an unsubstituted or substituted monovalent hydrocarbon group having 1 to 8 carbon atoms, and the following are exemplified.

_{CH 3 COOCH 3, CH 3 COOC} 2 H 5, CH 3 COO (n-C 3 H 7), CH 3 COO
_{(I-C 3 H 7)} , CH 3 COOC 4 H 9, CH 3 COOφ, CH 3 COOCH = C
_{H 2, C 2 H 5 COOCH} 3, C 2 H 5 COOC 2 H 5, C 2 H 5 COO (n-C 3 H 7),
C ₂ H ₅ COO (i-C ₃ H ₇ ), C ₂ H ₅ COOC ₄ H ₉ , C ₂ H ₅ COOφ, C ₂ H ₅ C
_{OOCH = CH 2, (n-} C 3 H 7) COOCH 3, (n-C 3 H 7) COOC
_{2 H 5, (n-C} 3 H 7) COOC (n-C 3 H 7), (n-C 3 H 7) COO
_{(I-C 3 H 7)} , (n-C 3 H 7) COOφ, CH 2 = CHCOO (n-C
_{3 H 7), (i-} C 3 H 7) COOCH 3, (i-C 3 H 7) COOC 2 H 5,
_{(I-C 3 H 7)} COO (i-C 3 H 7), (i-C 3 H 7) COOC 4 H 9,
_{(I-C 3 H 7)} COOφ, (i-C 3 H 7) COOCH = CH 2, C 4 H 9 COO
_{CH 3, C 4 H 9 COOC} 2 H 5, C 4 H 9 COO (n-C 3 H 7), C 4 H 9 COO (i
-C ₃ H ₇ ), C ₄ H ₉ COOC ₄ H ₉ , C ₄ H ₉ COOφ, C ₄ H ₉ COOCH = CH ₂ ,
φCOOCH ₂ , φCOOC ₂ H ₅ , φCOO (n-C ₃ H ₇ ), φCOO (i
-C ₃ H ₇ ), φCOOC ₄ H ₉ , φCOOφ, φCOOCH = CH ₂ , CH ₂ = C
_{HCOOCH 3, CH 2 = CHCOOC 2} H 5, CH 2 = CHCOO (n-C 3 H 7), C
_{H 2 = CHCOO (i-C} 3 H 7), CH 2 = CHCOOC 4 H 9, CH 2 = CHCOO
φ, CH ₂ = CHCOOCH = CH ₂ , (wherein φ represents a phenyl group).

The primer composition of the present invention comprises the reaction product of the three components A), B) and C) as a main component, and the reaction product is produced by mixing the three components A), B) and C). Then, the ester group —COOR ^{4 of the} carboxylic acid ester R ³ COOR ⁴ undergoes a stoichiometric exchange reaction with the alkoxide group of silicon and titanium, and this alkoxide group exchange reaction is electrophilic by the ester group —COOR ⁴ of the carboxylic acid ester. However, since the alkoxide groups of silicon and titanium are nucleophilic, they proceed even under mild conditions at room temperature and atmospheric pressure, so that this primer composition has these A), B), C). Although the three components can be prepared by simply mixing them, in order to obtain a superior effect of improving the adhesiveness of the composition, after mixing these components, the mixture is mixed at a temperature of 50 to 60 ° C.
It is advisable to react for ~ 3 hours, according to which component A)
Since the exchange reaction between the silicon alkoxide and the alkoxide group of the alkoxytitanium as the component B) and the ester group of the carboxylic acid ester is promoted, there is an advantage that the adhesiveness improving effect is increased.

In addition, A), B) in the primer composition,
The mixing ratio of C) components is 1 to 30% by weight, particularly 5 to 10% by weight of silicon alkoxide as the A) component, and 1 to 30% by weight, especially 5 to 10% of alkoxytitanium as the B) component.
And the carboxylic acid ester as component C) is 5% by weight.
˜98 wt%, especially 10 to 30 wt%.

The carboxylic acid ester as the component C) not only contributes to the exchange reaction with the alkoxides of the components A) and B), but can also be used as a solvent when it is blended in a stoichiometric amount or more.

For convenience of use, the primer composition contains 40-98% by weight of benzene, triene,
Xylene, methanol, ethanol, isopropyl alcohol, butanol, acetone, methyl ethyl ketone,
Solvents such as ligroin, heptane, hexane, cyclohexane, tetrahydrofuran, dioxane, etc. may be added, and various silane coupling agents, silicone resins, etc. may be added thereto within the range not impairing the object of the present invention.

The thus-prepared primer composition of the present invention activates the silicon atom, the titanium atom and the coordinating oxygen atom of the silicon and titanium alkoxides by the above-mentioned exchange reaction of the alkoxide group, and the silicon alkoxide and the titanium alkoxide are activated. Of the primer composition of the present invention, the affinity between the coating film of the primer composition of the present invention and the surface of the coated metal is improved, which improves the adhesiveness thereof. Therefore, the primer composition of the present invention is suitable. Brush on the surface of coated metal coated with fluororesin paint, urethane resin paint, acrylic resin paint, etc.
It may be applied by spraying, rolling, or the like, which provides an advantage that the surface of the coated metal can be favorably adhered to the condensation type room temperature curable silicone elastomer.

(Example) Next, the Example and comparative example of this invention are shown.

Examples 1 and 2, Comparative Examples 1 to 3 Tetramethoxysilane, tetraethoxysilane, tetrapropoxytitanium and acetic acid ester were mixed at the compounding ratio shown in Table 1, reacted at 50 ° C for 3 hours, and then mixed with hexane 5.0. 5 kinds of primer compositions were prepared by dissolving in 5 g of isopropyl alcohol and 50.0 g of isopropyl alcohol.

Then, two kinds of coated metal plates coated with a fluororesin-based paint and an acrylic resin-based paint were used as adherends, the surfaces of the coated metal plates were washed with toluene, and the primer composition obtained above was applied to this surface. Apply thinly by brush coating and dry to form a primer coating film, and apply a condensation type room temperature curable silicone elastomer composition that releases N, N-diethylhydroxyamine to the primer coating surface and cure it. The adhesion between the cured silicone elastomer after 14 days and the coated metal plate was examined according to the method of JIS-A578, and the results as shown in Table 2 were obtained. The primer composition of the present invention was obtained. In Examples 1 and 2 using the above, 100% of the coating cloth metal coated with the fluororesin-based paint and the acrylic resin-based paint was elastomer-destructed, while in Comparative Examples 1 to 3. 100% with respect to any of the coated metal was interfacial failure.

Example 3, Comparative Example 4 Tetraethoxysilane 2.0 g, γ-methacryloxypropyltrimethoxysilane 1.3 g, tetrabutoxytitanium 2.
A primer composition was prepared by mixing 8 g, methyl acetate (7.4 g) and isopropylchol (70 g) and reacting at 50-60 ° C. for 3 hours. The primer composition was processed in the same manner.

Then, these primer compositions are brushed on a coated metal surface coated with a fluororesin-based paint, an urethane resin-based paint and an acrylic resin-based paint as an adherend, and dried to form a primer coating film. When an adhesion test similar to that of Example 1 was conducted on 100% of the adherends, cohesive failure of the elastomer resulted in 100% of all adherends, showing good adhesion. All of the adherends had 100% interfacial failure regardless of the adherends, and did not show good adhesion.

(Effects of the Invention) The present invention relates to a primer composition, which comprises A) a silicon alkoxide or a (co) partial hydrolysis product thereof, and B) an alkoxytitanium or a (co) partial hydrolysis thereof, as described above. The main component is a decomposition product and a reaction product obtained by reacting three components of C) a carboxylic acid ester, which is formed by an exchange reaction between an alkoxide group of silicon and titanium and an ester group of a carboxylic acid ester. Silicon atoms, titanium atoms, and coordinated oxygen atoms are activated, and the interaction between silicon and titanium alkoxides is strengthened.These are used as condensation-type room temperature curable silicone elastomers and fluororesin-based paints and urethanes. When used for adhesion with resin-based paints, or even with painted metal coated with acrylic resin-based paints, this elastomer is peeled off. However, since it shows good adhesiveness that the entire amount of it will break the rubber, it is industrially useful as a primer composition for the purpose of adhering a condensation-type room temperature curable silicone elastomer to a coating metal. It has the advantage that

Claims (1)

(57) [Claims] 1. A) Silicon alkoxide represented by the general formula Si (OR ¹ ) ₄ (wherein R ¹ is an alkyl group having 1 to 8 carbon atoms) or a (co) partial hydrolysis product thereof, B) General Alkoxytitanium represented by the formula Ti (OR ² ) ₄ (wherein R ² is an alkyl group having 1 to 8 carbon atoms) or a (co) partial hydrolysis product thereof, C) General formula R ³ COOR ⁴ (here R ³ , R ⁴ is the same or different and is a carboxylic acid ester represented by an unsubstituted or substituted monovalent hydrocarbon group), which is a main component of the reaction product.