JPH0674317B2 - 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.

[Conventional technology]

Multi-layered elastic paint used for painting exterior walls of buildings, or paint for painting elastic material moldings such as urethane foam, thermoplastic urethane, EPDM, and vinyl chloride resin, which are widely used for interior and exterior parts of automobiles. Is required to have excellent flexibility as well as excellent weather resistance, solvent resistance, impact resistance, chemical resistance, drying property, low temperature property and the like.

A one-component non-yellowing urethane coating is used to coat the above elastic material molded products, but this coating 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%.
There is a drawback that the coating film obtained by coating once is extremely thin.

On the other hand, the two-component polyol-curable urethane coating material is generally excellent in solvent resistance and spraying properties, but lacks flexibility and dryness as compared with the above-mentioned one-component urethane coating material.

In addition, using a two-component polyol curable urethane coating,
An acrylic polyol or polyester polyol having a low glass transition point is effective as a film forming resin component for obtaining a flexible cured film, but a cured film obtained from an acrylic polyol having a low glass transition point and an isocyanate compound. Has flexibility, but has the drawback of insufficient hardness and solvent resistance.

[Problems to be solved by the invention]

The present invention has been made to solve the above problems, and has excellent weather resistance, dryness to the touch and flexibility of a one-component urethane coating and excellent properties of a two-component polyol curable urethane coating. An object of the present invention is to provide a one-pack type room temperature curable resin composition for an elastic material, which also has solvent resistance.

[Means for solving problems]

The present invention has excellent weather resistance of a one-component urethane coating,
As a result of diligent studies to obtain a one-pack type curable composition for elastic materials, which has dryness to the touch, flexibility and excellent solvent resistance of the two-pack polyol-curable urethane coating, (A) molecular weight An expression with 2,000 to 50,000 [Wherein R ₁ is hydrogen or a methyl group, R ₂ is an alkylene group having ₂ to 4 carbon atoms] or a formula [However, R ₃ is an alkyl group having 1 to 3 carbon atoms]
The copolymer having at least one compound represented by the formula (5) to 95 parts by weight of a copolymer having an isocyanate group in the side chain obtained by copolymerization with a vinyl-based monomer and (B) having a molecular weight having an isocyanate group at the terminal are 500-5,00
The inventors have found that by blending 95 to 5 parts by weight of the urethane prepolymer of No. 0, touch-drying property, flexibility, solvent resistance and weather resistance can be imparted, and the present invention has been completed.

[Action]

After forming a film, the room temperature curable resin composition of the present invention (1) reacts moisture in the atmosphere with an isocyanate group in the composition 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.

That is, by the reaction path as described above, the main chain is composed of carbon-carbon bonds, the copolymer having an isocyanate group in the side chain and the urethane prepolymer having an isocyanate group at the end are cross-linked to form a one-pack urethane paint. A one-pack type room temperature curable resin composition for elastic material having excellent weather resistance, touch-drying property, flexibility and excellent solvent resistance of a two-component polyol-curable urethane coating is obtained. It seems to be.

An example of cross-linking is shown in the model [A]: Copolymer Having Isocyanate Group in Side Chain [B]: Urethane Prepolymer Having Isocyanate Group in Terminal [Embodiment] The constitution of the present invention will be described in detail below.

The copolymer having a side chain isocyanate group used as the component (A) of the present invention, the main chain is carbon-carbon, the unsaturated isocyanate compound of formula [I] or formula [II] and vinyl The molecular weight obtained by the copolymerization of the system monomers is 2,000
It is a copolymer of 0 to 50,000. Specific examples of the unsaturated isocyanate compound providing an isocyanate group include isocyanate ethyl acrylate belonging to the formula [I], isocyanate ethyl methacrylate, isocyanate propyl acrylate, isocyanate propyl methacrylate, and formula [II]. Methacryloyl isocyanate may be mentioned, of which isocyanatoethyl methacrylate is preferred.

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, γ-methacryloxypropyltrimethoxysilane, glycidyl (meth) acrylate and other (meth) acrylic acid esters, and styrene, p-methylstyrene, α -Aromatic vinyl compounds such as methylstyrene; use of acrylonitrile, methacrylonitrile and the like 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; vinyl-containing halogen compounds such as vinylidene chloride, vinyl chloride, vinyl fluoride; olefins such as ethylene.

Has an isocyanate group on the side chain and a molecular weight of 2,000 to 50,00
The amount of isocyanate groups in the copolymer, which is 0, is 0.25.
It is necessary to copolymerize the unsaturated isocyanate compound in an amount of -15% by weight, preferably 0.5-10% by weight. That is, the molecular weight of the copolymer is from the viewpoints of touch dryness, compatibility with urethane prepolymer and reactivity with moisture in the air.
It is preferably 2,000 to 50,000, and when the amount of the isocyanate group in the copolymer is 0.25% by weight or less, the effect is not exhibited, and when it is 15% by weight or more, the copolymer becomes expensive, which is not practical.

The urethane prepolymer having an isocyanate group at the terminal and having a molecular weight of 500 to 5,000, which is used as the component (B) of the present invention, is obtained by a reaction between a polyol component and a polyisocyanate component. That is, when the molecular weight is less than 500, the compatibility with the copolymer having an isocyanate group in the side chain is good, but the coating film becomes hard, lacks flexibility, and the extensibility at low temperature 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; polyethylene adipate, polydiethylene adipate, polypropylene adipate, polybutylene adipate, polyhexamethylene adipate, poly ε-caprolactone polyol, copolymerized caprolactone polyol. Examples thereof include polyester polyols having a hydroxy group at the same end; hydroxy group-terminated polybutadiene and hydrogenated products thereof. As the polyisocyanate component, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate,
Mixture of 2,4-tolylene diisocyanate and 2,6-tolylene diisocyanate, diphenylmethane diisocyanate, 1,5-naphthylene diisocyanate, paraphenylene diisocyanate, xylylene diisocyanate, isophorone diisocyanate , 1,6-hexamethylene diisocyanate, hydrogenated xylylene diisocyanate, and other polyisocyanates. The reaction ratio of both components is such that the polyisocyanate component is 0.8 to 1 mol per 1 hydrogen group in the polyol component.

For applications requiring yellowing-free modification, it is preferable to use a combination of polyester polyol and aliphatic polyisocyanate.

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,
Has reactivity with hydroxy group-free glycol ethers such as 2-methoxyethyl acetate, ketones such as methyl ethyl ketone and methyl isobutyl ketone, and isocyanate groups such as chlorine-containing solvents such as 1,1,1-trichloroethane and trichloroethylene. The solvent which does not contain active hydrogen can be mentioned. 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 or 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, a filler pigment, a paint and the like.

〔Example〕

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

Synthesis of Acrylic Copolymer Having Isocyanate Group in Side Chain Synthesis Example 1 132 g of toluene was charged into a one-separable flask equipped with a stirrer, dropping funnel, thermometer, nitrogen introducing tube, condenser with calcium chloride tube, and nitrogen was added. Heated while introducing gas. After the liquid temperature reached the boiling point of toluene and the system was replaced with nitrogen for 30 minutes after starting to reflux, 120 g of methyl methacrylate, 30 g of styrene, 20 g of isocyanate ethyl methacrylate, 2-
A mixed solution of 30 g of ethylhexyl acrylate and 1.6 g of azobisisobutyronitrile was added dropwise over 3 hours. After completion of dropping, the mixture was aged for 1 hour, and then 1 g of azobisisobutyronitrile was added 6 times and added every 10 minutes. After the addition was completed, the mixture was aged for another 1 hour, and 240 g of toluene was added.
Cooled to room temperature. Polymerization rate 99.5%, nonvolatile content 35.1%,
The number average molecular weight was 15,000. The presence of an isocyanate group (2260 cm ^-1 ) was confirmed with a 270-30 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. The results are shown in Table 1.

Synthesis of Urethane Prepolymer Having Isocyanate Group at Terminal Synthetic Example 5 After replacing the inside of a one-separable flask equipped with a stirrer, a thermometer, a nitrogen gas introduction tube, and a condenser with a calcium chloride tube with nitrogen, a poly (molecular weight 550) 110 g of caprolactone diol (Placcel 205, manufactured by Daicel Chemical), 67.2 g of hexamethylene diisocyanate, and 177.2 g of toluene were charged. Next, the separable flask was heated and reacted at 80 ° C. for 8 hours. The reaction rate was 99.8% 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. The results are shown in Table 2.

Examples 1 to 8 and Comparative Examples 1 to 3 The side chain isocyanate copolymers prepared in Synthesis Examples 1 to 4 and the terminal isocyanate urethane prepolymers prepared in Synthesis Examples 5 to 8 were used at the compounding ratios shown in Table 3. The mixture was mixed to prepare a room temperature curable resin composition. The respective compounding ratios are shown in Table 3.

Intermediate coating material for multi-layered elastic paint on release paper (Polysol A _p 635,
Showa High Polymer Co., Ltd.) applied to a thickness of 2 mm 24
The clear coating composition prepared in Examples 1 to 8 and Comparative Examples 1 to 3 was applied as an overcoat on the film dried for an hour,
The low temperature flexibility (solvent resistance) was measured.

For the adhesion, instead of preparing the sample on the release paper, the sample coated on the slate plate was used. For other tests, a sample coated on a glass plate was used. The measurement results are shown in Table 4.

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 touch dryness and hardness.

[Effect of the invention] The room temperature curable composition of the present invention has excellent flexibility, weather resistance, and
Not only effective as a paint for elastic material moldings used for interior and exterior parts of automobiles that require solvent resistance, impact resistance, chemical resistance, drying properties, low temperature characteristics, etc., but also for coating exterior walls of buildings. It can be used as a top coat for multi-layered elastic paints used for, or as a waterproofing agent for coating films.

Claims (1)

[Claims] 1. A formula (A) having a molecular weight of 2,000 to 50,000. [Wherein R ₁ is hydrogen or a methyl group, R ₂ is an alkylene group having ₂ to 4 carbon atoms] or a formula [However, R ₃ is an alkyl group having 1 to 3 carbon atoms]
The copolymer having at least one compound represented by the formula (5) and a vinyl-based monomer having 5 to 95 parts by weight of a copolymer having an isocyanate group in the side chain and (B) having a molecular weight having an isocyanate group at the end are 500 ~
A room temperature curable resin composition comprising 95 to 5 parts by weight of 5,000 urethane prepolymers.