JPH0674318B2 - Room temperature curable resin composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention forms and hardens a network structure by moisture in the atmosphere to form a film having stretchability with improved dry-to-touch property, weather resistance and hardness. The one-pack type curable resin composition is extremely useful for one-pack type moisture-curable elastic paint.

[Prior Art] There is a great demand for a resin that can be cured without using a curing agent, that is, a synthetic resin coating agent that is generally called a one-pack type curable resin. It has been attempted to be applied to chemicals and paper coating agents. For this kind of resin It is difficult to obtain a vinyl-based copolymer (hereinafter referred to as "hydrolyzable silane group") 1 or more (JP-A-54-36395) or a stable copolymer having a large gelation tendency with the passage of time, but 2 isocyanate groups. Modified copolymer containing the above (Japanese Patent Publication No. 59-837)
5), etc., and attempts to produce room temperature curable one-pack type copolymers are being actively made. However, in these fields of application, good adhesiveness (adhesiveness) is required for many types of base materials, but isocyanate group-containing copolymers are not suitable for isocyanate group reactivity and hydrolyzable silane group-containing copolymers. The polymer expresses only the reactivity of the hydrolyzable silane group, and thus the adherend is selected and preferred. That is, the isocyanate group-containing copolymer has good adhesion to the adherend having an active hydrogen group, and the hydrolyzable silane group-containing copolymer has a good adhesion to the adherend having a silanol group. It is good, but when the adherends are exchanged with each other, good results have not been obtained.

In addition, it can be used as a paint for coating elastic multi-layer paints used for painting the exterior walls of buildings or elastic material moldings such as urethane foam, thermoplastic urethane, and vinyl chloride resin that are widely used for interior and exterior parts of automobiles. Excellent flexibility and weather resistance, solvent resistance, impact resistance, chemical resistance,
Dryability and low temperature characteristics are required.

One-component non-yellowing urethane paint is used for coating the above elastic material molded products, but this paint has excellent flexibility, weather resistance, and dryness to the touch. There is a problem in sprayability and sprayability. Also, since this paint is provided as a high-polymerization degree urethane solution, it must be diluted during coating to adjust the resin content to about 5-20%.
The disadvantage is that the coating film obtained by one coating is extremely thin.

On the other hand, a two-component polyol-curable urethane coating or a one-component moisture-curable coating is generally superior in solvent resistance and spray characteristics, but it is more flexible and dry than the above-mentioned one-component urethane coating. Missing.

Further, in order to obtain a flexible cured film by using a two-component polyol-curable urethane coating material or a one-component moisture-curable coating material, a polyol having a low glass transition point or an isocyanate group is contained as a film forming resin component. Although a copolymer modified product is effective, a cured film obtained from a polyol having a low glass transition point and an isocyanate compound or an isocyanate group-containing copolymer modified product has flexibility, but hardness and There is a drawback that the solvent resistance is not sufficient.

[Problems to be Solved by the Invention] The present invention has been made to solve the above problems.
Taking advantage of the reactivity of the isocyanate group and the reactivity of the hydrolyzable silane group, complementing the disadvantages, regardless of the adherend, it has adhesiveness to a wide range of materials and at the same time has the one-component urethane paint One-component room-temperature curable resin composition having excellent weather resistance, dryness to the touch and flexibility and excellent solvent resistance of a two-component polyol-curable urethane coating or a one-component moisture-curable coating It is an attempt to provide something.

[Means for Solving Problems] The present inventor does not choose an adherend and has adhesiveness to a wide range of materials, and at the same time, has excellent weather resistance, dryness to the touch, and flexibility that a one-component urethane paint has. As a result of earnest studies to obtain a one-pack type room temperature curable resin composition having both excellent solvent resistance of a two-component polyol-curable urethane coating composition and a one-component moisture-curable coating composition, (A ) The main chain consists of carbon-carbon bonds, and the side chain has an isocyanate group and a hydrolyzable silane group (based on Si atom)
Having a molecular weight of 2,000 to 50,000
5 parts by weight and (B) the molecular weight of having an isocyanate group at the end is 500 to 5,000.
By blending 95 to 5 parts by weight of the urethane prepolymer of 0, it has adhesiveness to a wide range of materials regardless of the adherend, and at the same time weather resistance, touch dryness, flexibility, solvent resistance They have found that they can be imparted, and have completed the present invention.

[Work]

Since the room temperature curable resin composition of the present invention has 1) an isocyanate group and a hydrolyzable silane group, the former causes a chemical reaction with an organic product having active hydrogen and adheres by a urethane bond. The latter is highly reactive with inorganic products and adheres via siloxane bonds. And since the main chain is made of vinyl-based polymer, ordinary coating base material, cement-based products that are primer or topcoat, urethane-based products, silicone-based products, vinyl-based products and adherends, Shows effective adhesion to a wide range of materials.

2) The room temperature curable resin composition of the present invention is formed with a film, and then A]
(1) Isocyanate group reacts with atmospheric moisture to form carbamic acid. (2) Next, when the isocyanate group reacts with the generated carbamic acid, carbamic anhydride is generated and crosslinked. (3) Alternatively, carbamic acid is decarboxylated to produce an amine. Next, (a) when an isocyanate reacts with the formed amine, a urea bond is formed and crosslinked.
When (b) or carbamic acid reacts with each other, it is considered that an amine salt of carbamic acid is formed and cross-linked.

B] (1) The hydrolyzable silane group reacts with atmospheric moisture to form a silanol group. (2) Next, the silanol groups generated form a dehydration reaction to form a siloxane bond and crosslink.

That is, by the reaction path as described above, the main chain is composed of carbon-carbon bonds, the side chain has a copolymer having an isocyanate group and a hydrolyzable silane group, and the urethane prepolymer having an isocyanate group at the end is crosslinked. However, a one-pack type room temperature curable resin composition having the excellent weather resistance, dry-to-touch property and flexibility of a one-pack urethane coating and the excellent solvent resistance of a two-pack polyol-curing urethane coating Seems to be obtained.

Hereinafter, the configuration of the present invention will be described in detail.

The main chain of the copolymer having an isocyanate group and a hydrolyzable silane group in the side chain of the present invention is carbon-carbon, and the unsaturated isocyanate compound of the following formula [I] or formula [II] and the formula It is a copolymer having a molecular weight of 2,000 to 50,000 obtained by copolymerizing a polymerizable silane compound having a hydrolyzable silane group of [III] and a vinyl monomer.

The unsaturated isocyanate compound used in the present invention has the general formula [Wherein R ₁ is hydrogen or a methyl group, R ₂ is an alkylene group having ₂ to 4 carbon atoms] or the general formula [However, R ₃ is represented by an alkyl group having 1 to ₃ carbon atoms].

Specific examples of the unsaturated isocyanate compound include isocyanate ethyl acrylate, isocyanate ethyl methacrylate, isocyanate propyl acrylate, isocyanate propyl acrylate, α-alkyl acryloyl isocyanate represented by methacryloyl isocyanate, and the like. Natoethyl methacrylate is preferred.

Further, the polymerizable silane compound used in the present invention is represented by the general formula R ₄ —Si (R ₅ ) _a X _{3 -a} [III] [wherein R ₄ is an unsaturated group having a radical polymerizable double bond, R ₅ is a hydrocarbon group having 1 to 10 carbon atoms, X is an alkoxy group, an acyloxy group or an aminooxy group, and a is 0, 1 or 2. ] Is represented. Representative examples include vinyltriethoxysilane, γ-methacryloxypropyltrimethoxysilane, and γ-acryloxypropyltrimethoxysilane.

Further, the vinyl-based monomer used as the main chain component in the present invention includes vinyl esters such as vinyl acetate, vinyl propionate and vinyl versatate; methyl (meth) acrylate, ethyl (meth) acrylate,
Butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, bornyl methacrylate, glycidyl (meth) acrylate and other (meth) acrylic acid esters, and aromatic vinyl compounds such as styrene, P-methylstyrene and α-methylstyrene In addition, the use of acrylonitrile, methacrylonitrile, etc. is particularly effective.

In addition, in general, any radical-polymerizable monomer having no active hydrogen that reacts with an isocyanate group can be used as the vinyl-based monomer of the present invention. Examples thereof include vinyl ethers such as: vinylidene chloride, vinyl chloride, vinyl fluoride, and other halogen-containing vinyl compounds; olefins such as ethylene.

It has an isocyanate group and a hydrolyzable silane group in the side chain,
The amount of functional groups in the copolymer having a molecular weight of 2,000 to 50,000 is 0.25 to 15% by weight as an isocyanate group, preferably 0.
5-10% by weight, hydrolyzable silane groups (based on Si atoms) 0.2-10% by weight, preferably 0.4-7.5% by weight are required.

That is, from the viewpoint of touch dryness, compatibility with urethane prepolymer and reactivity with moisture in the air, the molecular weight of the copolymer is preferably 2,000 to 50,000, and the amount of the isocyanate group in the copolymer is 0.25. % By weight, the amount of hydrolyzable silane groups is 0.
If the amount is less than 2% by weight, no effect is exhibited, and if the amount of the isocyanate group is 15% by weight and the amount of the hydrolyzable silane group is 10% by weight or more, the copolymer becomes expensive, which is not practical.

The urethane prepolymer having an isocyanate group at the end and having a molecular weight of 500 to 5,000 used in the present invention can be obtained by reacting a polyol component with a polyisocyanate component. That is, when the molecular weight is less than 500, the compatibility with the copolymer having an isocyanate group and a hydrolyzable silane group in the side chain is good, but the coating becomes hard, lacks flexibility, and stretches at low temperatures. Sex decreases. When the molecular weight is more than 5,000, the polymer is rich in flexibility and has good elongation at low temperature, but it causes a problem in compatibility with a copolymer having an isocyanate group in a side chain.

Examples of the polyol component include polyether polyols such as polyethylene glycol, polypropylene glycol, polybutylene glycol; polydiethylene adipate, polypropylene adipate, polybutylene adipate, polyhexamethylene adipate, poly ε-caprolactone polyol, copolymerized caprolactone polyol, etc. Polyester polyols having a hydroxy group in the following; hydroxy-terminated polybutadiene and hydrogenated products thereof, and the like.

As the polyisocyanate component, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, a mixture of 2,4-tolylene diisocyanate and 2,6-tolylene diisocyanate, diphenylmethane diisocyanate, Examples thereof include polyisocyanates such as 1,5-naphthylene diisocyanate, paraphenylene diisocyanate, xylylene diisocyanate, isophorone diisocyanate, 1,6-hexamethylene diisocyanate, and hydrogenated xylylene diisocyanate.

The reaction ratio of both components is such that the polyisocyanate component is 0.8 to 1 mol with respect to one hydroxyl group in the polyol component. In addition, it is preferable to use a combination of a polyester polyol and an aliphatic polyisocyanate for applications requiring non-yellowing.

The room temperature curable resin composition of the present invention is conveniently used with a solvent. As the solvent used, toluene, xylene, aromatic hydrocarbons such as Solvesso # 100, ethyl acetate, esters such as butyl acetate, 1,4-dioxane,
Hydroxy group-free glycol ethers such as 2-methoxyethyl acetate, ketones such as methyl ethyl ketone and methyl isobutyl ketone, and chlorine-containing solvents such as 1,1,1-trichloroethane and trichloroethylene can be used.

The solvent is preferably added as a reaction solvent at the time of producing the copolymer or urethane prepolymer. Further, a known urethanization catalyst such as an organic metal compound, a metal salt, and a tertiary amine may be used in the room temperature curable resin composition of the present invention, if necessary.

Further, the room temperature curable resin composition of the present invention may be optionally used in combination with a plasticizer such as phthalic acid ester, a bituminous substance such as tar or the like, a filler, a pigment and a paint.

〔Example〕

 Hereinafter, the present invention will be described in more detail with reference to examples.

Synthesis of Acrylic Copolymer Having Isocyanate Group and Hydrolyzable Silane Group in Side Chain <Synthesis Example 1> 1 separable equipped with a stirrer, a dropping funnel, a thermometer, a nitrogen introducing tube, and a condenser with a calcium chloride tube A flask was charged with 132 g of toluene and heated while introducing nitrogen gas. After the liquid temperature reached the boiling point of toluene and after starting refluxing for 30 minutes, the system was replaced with nitrogen, and then 115 g of methyl methacrylate, 30 g of styrene, 30 g of 2-ethylhexyl acrylate, 20 g of isocyanate ethyl methacrylate, γ-methacryloxypropyltrimethoxy. A mixed solution of 5 g of silane and 1.6 g of azobisisobutyronitrile was added dropwise over 3 hours. After completion of the dropping, aging was carried out for 1 hour, and then 1 g of azobisisobutyronitrile was added in 6 batches and added every 10 minutes. After the addition was completed, the mixture was aged for 1 hour, 240 g of toluene was added, and then cooled to room temperature.

The nonvolatile content was 35.2% and the number average molecular weight was 15600. 270-30
The presence of an isocyanate group (2260 cm ^-1 ) and -Si-O-CH ₃ (1,100 cm ^-1 ) was confirmed with a type infrared spectrophotometer (manufactured by Hitachi).

<Synthesis Examples 2 to 4> Copolymers were synthesized in the same manner as in Synthesis Example 1 except that the monomers shown in Table 1 were used.

Synthesis of Urethane Prepolymer Having Isocyanate Group at Terminal <Synthesis Example 5> After a nitrogen atmosphere was substituted in a one-separable flask equipped with a stirrer, a thermometer, a nitrogen gas introducing tube, and a condenser with a calcium chloride tube, a molecular weight of 550 was obtained. 110 g of polycaprolactone diol (Placcel 205, manufactured by Daicel Chemical Industries, Ltd.), 67.2 g of hexamethylene diisocyanate, and 177.2 g of toluene were charged. Next, Separable Franceco was heated and reacted at 80 ° C. for 8 hours. The yield was 99.5% and the nonvolatile content was 50.2%.

<Synthesis Examples 6 to 8> Urethane prepolymers were synthesized in the same manner as in Synthesis Example 5 except that the raw materials shown in Table 2 were used.

<Examples 1 to 8> The copolymers prepared in Synthesis Examples 1 to 4 and the terminal isocyanate urethane prepolymers prepared in Synthesis Examples 5 to 8 were mixed at the following compounding ratios to prepare room temperature curable resin compositions. did.

From the above results, it is clear that the film obtained from the composition of the present invention has excellent low-temperature flexibility, hardness, and dryness to the touch, whereas the films of Comparative Examples have excellent dryness to the touch and hardness. Those having low temperature flexibility were inferior, and those having excellent low temperature flexibility were inferior in dryness to touch and hardness.

<Synthesis Examples 9 to 11> Copolymers were synthesized in the same manner as in Synthesis Example 1 except that the monomers shown in Table 5 were used.

<Example 9 and Comparative Examples 4 and 5> The copolymers prepared in Synthesis Examples 9 to 11 and the terminal isocyanate urethane prepolymer prepared in Synthesis Example 6 were mixed at a ratio of 4: 6 and evaluated as a primer ( According to JIS A-5758), the results are shown in Table 6.

From the above results, it is clear that when the composition of the present invention is used as a primer, it has good adhesion to any of the commercially available caulks (acrylic type, urethane type, silicone type), whereas the primer of Comparative Example The composition using the copolymer containing only the isocyanate of Example 10 has good adhesion to acrylic and urethane types, but causes interfacial peeling to silicone type. A composition using a copolymer containing only a hydrolyzable silane group of Synthesis Example 11 has good adhesion to a silicon-based material, but an acrylic-based material.
For urethane type, interfacial peeling and cohesive collapse were mixed.

[Advantages of the Invention] 1. Since the copolymer, which is one component of the room temperature curable composition of the present invention, contains both an isocyanate group and a hydrolyzable silane group, an organic product or an inorganic substance can be selected without selecting an adherend. Good adhesion to any adherend of the product.

2. The room temperature curable composition of the present invention is used for interior and exterior parts of automobiles which are required to have excellent flexibility, weather resistance, solvent resistance, impact resistance, chemical resistance, drying property, low temperature characteristics and the like. It is not only effective as a paint for molded articles made of elastic materials, but can also be used as a top coat for multi-layer elastic paints used for coating exterior walls of buildings or waterproofing agents for coating films.

Claims (2)

[Claims] 1. A main chain (A) comprises a carbon-carbon bond, and has a side chain having an isocyanate group and a hydrolyzable silane group.
5 to 95 parts by weight of a copolymer having a molecular weight of 2,000 to 50,000, and (B) a molecular weight of 500 to 5,000 having an isocyanate group at the terminal.
A room temperature curable resin composition, characterized by being blended with 95 to 5 parts by weight of the urethane prepolymer of No. 0. 2. A copolymer represented by the general formula (a) [Wherein R ₁ is hydrogen or a methyl group, R ₂ is an alkylene group having ₂ to 4 carbon atoms] or the general formula [Wherein R ₃ is an alkyl group having 1 to ₃ carbon atoms] and at least one unsaturated isocyanate compound and (b) the general formula R ₄ —Si (R ₅ ) _a X _3-a [III [Wherein R ₄ is an unsaturated group having a radically polymerizable double bond, R ₅ is a hydrocarbon group having 1 to 10 carbon atoms, X is an alkoxy group, an acyloxy group or an aminooxy group, and a is 0 or 1 or It is 2. ] The polymerizable silane compound represented by and (c) the main chain obtained by copolymerizing the vinyl-based monomer is composed of carbon-carbon bond, the side chain 0.25 to 15 wt% of an isocyanate group and 0.2 to 10 The room temperature curable resin composition according to claim 1, wherein the copolymer having a molecular weight of 2,000 to 50,000 having a hydrolyzable silane group in a weight percentage is used.