JPH06157987A - Method for applying polyurethane resin coating - Google Patents

Abstract

PURPOSE:To rapidly cure the subject coating at a low temperature, solve troubles such as heat deformation of a substrate due to heating and simultaneously improve the productivity by applying a specific undercoating material onto the substrate and then applying a polyurethane resin coating. CONSTITUTION:An undercoating material containing preferably 2-5wt.% compound capable of promoting the curing reaction of a polyurethane resin coating (e.g. a tin compound such as dibutyltin.dilaurate or a tertiary amine such as triethylenediamine) is initially applied onto a substrate to be coated with the polyurethane resin coating, which is then applied to the undercoating material. Furthermore, the undercoating material is preferably obtained by blending a resin component such as a thermoplastic polyurethane elastomer with a solvent such as toluene, further blending the resultant blend as a base with the compound capable of promoting the curing reaction of the polyurethane resin coating and simultaneously regulating the viscosity thereof to 30-300cP.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention provides a decorative material used in various industrial fields such as building materials, home electric appliances, interior materials for automobiles, etc. by applying a polyurethane resin coating on a substrate such as a plastic sheet and curing it. The present invention relates to a method for applying a polyurethane resin coating, in particular, a polyurethane resin coating at a low temperature,
In addition, it cures quickly and solves problems caused by heat such as heat deformation and heat deterioration of the base material, and also improves productivity.
In addition to this, the present invention relates to a method for applying a polyurethane resin paint, which extends the pot life of the paint.

[0002]

2. Description of the Related Art Decorative materials used in various industrial fields such as building materials, home electric appliances, interior materials for automobiles, etc. are usually sheet-like base materials such as plastics coated with polyurethane resin paint, gravure printing method, roll coater method, It can be obtained by applying a knife coater method, a rod coater method, a rotary screen printing method, or the like, followed by an addition polymerization reaction and curing to form a polymer coating film having a three-dimensional network structure.

The above-mentioned polyurethane resin coatings are usually (1) "moisture-curable" having an isocyanate group at the end of the prepolymer or polymer molecule, (2) at the end of the main chain or side chain of the prepolymer or polymer molecule. , A hydroxyl group, a compound having one or more functional groups containing active hydrogen such as a carboxylic acid group, and a "two-component curing type" consisting of a mixed system of a polyisocyanate compound having a plurality of isocyanate groups in one molecule, (3) "One-component thermosetting" paints that have a latent reaction curing agent, which is obtained by adding phenol, primary alcohol, etc. to a compound having multiple isocyanate groups in one molecule, Used.

Usually, these polyurethane resin coating materials are cured by heating to cause an addition polymerization reaction to be cured. However, since these compounds have a slower rate of polymerization reaction than other paint systems, they have traditionally been subjected to (a) high temperature heating of the reaction system, or (b)
The reaction rate is increased by means such as mixing a catalyst or an additive that accelerates the reaction with the coating material.

[0005]

[Problems to be Solved by the Invention] However, these (a)
And (b) have the following drawbacks. (B) When the reaction system is heated at a high temperature, for example, it is heated at a temperature of 100 to 150 ° C. Therefore, in the case of a sheet-shaped base material such as plastic, the base material undergoes thermal deformation or thermal deterioration, resulting in dimensional change and strength reduction Will cause problems such as.

(B) In the method of mixing a catalyst or an additive for accelerating the reaction, when 4 to 8 hours have passed since the addition of these, the viscosity was increased and the work became impossible, or gelation occurred to cause fluidity. Lost, causing damage to the equipment. For this reason, it is necessary to constantly grasp the amount of paint used over time, the increase in viscosity, and the like in order to progress the work. Therefore, when the amount of coating material used per unit time is small, the coating appearance and physical properties change due to thickening over time, and this method is difficult to use.

Therefore, an object of the present invention is to cure a polyurethane resin coating material at a low temperature to solve problems caused by heat such as thermal deformation and thermal deterioration of a substrate, and further extend the pot life of the coating material. It is an object of the present invention to provide a method for coating a polyurethane resin paint, which improves the drawbacks of the known technique and rapidly cures the paint to improve the productivity.

[0008]

In order to achieve the above object, according to the present invention, when a polyurethane resin coating is applied, first, a curing reaction of the polyurethane resin coating is performed on a substrate to be applied. It is characterized in that an undercoat material containing a compound for promoting is applied, and then a polyurethane resin paint is applied thereon.

[0009]

According to the present invention having the above-mentioned constitution, prior to applying the polyurethane resin coating on the substrate, an undercoat material containing a compound that accelerates the curing reaction of the polyurethane resin coating is applied on the substrate in advance. Therefore, the contact with this compound accelerates the curing reaction of the coating material, and the curing proceeds without the conventional heat curing. Moreover, the curing can be rapidly achieved by appropriately selecting the compound that accelerates the curing reaction.

Furthermore, in the above-mentioned present invention, since the curing reaction is promoted by the curing-accelerating compound contained in the above-mentioned undercoat material, it is not necessary to mix a catalyst or an additive which accelerates the reaction with the coating as in the conventional case. Therefore, the pot life of the paint is extended.

[0011]

DETAILED DESCRIPTION OF THE INVENTION The present invention will be described in detail below with reference to the accompanying drawings. FIG. 1 is a sectional view for explaining the coating method of the present invention.

In FIG. 1, reference numeral 1 is a base material. This base material 1 is, for example, a semi-rigid sheet made of polyvinyl chloride resin,
Although it has a thickness of about 150 μm, it may be a sheet-shaped or plate-shaped substrate made of various plastics.

An undercoat material 2 is applied on the base material 1 described above. This undercoat material 2 contains a resin component such as a hydroxyl group-containing vinyl chloride / vinyl acetate copolymer, a thermoplastic polyurethane elastomer, and a solvent such as toluene, methyl ethyl ketone, ethyl acetate, isopropyl alcohol, for example, a resin component.
20: Solvent 80 (parts by weight) is used as a base, and a compound that accelerates the curing reaction of the polyurethane resin coating, for example, a tin compound such as dibutyl tin dilaurate or dibutyl tin maleate, a tri compound Aliphatic tertiary amines such as ethylenediamine, aromatic tertiary amines, metallic soap, vanadium oxide, etc., alone or in combination of 1 to 10% by weight, preferably 2 to 5% by weight
In addition, if necessary, for the purpose of expanding the surface area,
It is constituted by containing several weight% of additives such as silica powder or polycarbonate powder. The viscosity of the undercoat material 2 is the base material 1
It is preferably 30 to 300 cps in order to facilitate application to the skin.

The base material 1 is coated with the undercoat material 2 by a method such as a gravure printing method, a roll coater method, a knife coater method, a rod coater method, or a rotary screen printing method at 5 to 50 g / It is carried out continuously with a coating amount of m ² . After application, the undercoat material 2 should be 50
Warm air at -80 ° C, preferably 60 ° C is blown onto the coated surface for 30 to 120 seconds to forcibly evaporate the solvent component and dry.

Next, the polyurethane resin coating material 3 is applied onto the undercoat material 2 described above. The polyurethane resin coating material 3 is mainly composed of a polyurethane resin having an isocyanate group, and also contains additives such as silica powder, magnesium carbonate, and polycarbonate powder. 10 ~ 100
It is a paint adjusted to cps. The polyurethane resin having an isocyanate group is specifically shown in the following (1) to (3).

(1) A moisture-curable resin having an isocyanate group at the end of a prepolymer or polymer molecule. Specifically, Seika Bond C-112s (Dainichi Seika Kogyo Co., Ltd.)
Manufactured by Olestar M54-80A (manufactured by Mitsui Toatsu Chemicals, Inc.) and the like.

(2) A compound having one or more functional groups having active hydrogen such as a hydroxyl group and a carboxylic acid group at the terminal of the main chain or side chain of the prepolymer or polymer molecule, and a plurality of compounds in one molecule. A two-component curable resin composed of a mixed system with a polyisocyanate compound having an isocyanate group. Specifically, a mixture of a fatty acid-modified polyester resin (hydroxyl group content 2%) and a polyisocyanate curing agent (isocyanate content 12%), such as Desmohen R
D-181 (Sumitomo Bayer Urethane Co., Ltd.), Takenate D-110N (Takeda Pharmaceutical Co., Ltd.) and the like can be mentioned.

(3) A one-part thermosetting resin having a latent reactive curing agent, which is obtained by adding phenol, primary alcohol, etc. to a compound having a plurality of isocyanate groups in one molecule. Specific examples thereof include Duranate 17B-60PX (manufactured by Asahi Kasei Corp.).

The application of the polyurethane resin paint 3 on the undercoat material 2 is carried out in the same manner as the undercoat material 2 by, for example, a gravure printing method, a roll coater method, a knife coater method, a rod coater method, a rotary screen printing method or the like. It is continuously carried out with a coating amount of 5 to 50 g / m ² . After application, warm air at 50-80 ℃, preferably 60 ℃ is 30-1
The coated surface is sprayed and dried for 20 seconds, preferably 2 minutes, and wound to complete the coating treatment of the present invention.

In the present invention having the above structure, the undercoat material 2 is used.
Then, the above-mentioned undercoat material may be further applied onto the two layers of the polyurethane resin coating material 3, then the polyurethane resin coating material may be applied thereon, and this coating step may be repeated.

In the present invention, the polyurethane resin coating material may be applied on the base material 1 in advance, the undercoat material 2 may be applied thereon, and then the polyurethane resin coating material 3 may be applied thereon. Alternatively, the undercoat material 2 may be further applied onto these three layers, and then the polyurethane resin coating material 3 may be applied thereon, and this application step may be repeated.

[0022]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be specifically described below with reference to Examples. Example A semi-hard sheet (150 μm thick) made of polyvinyl chloride resin was used as the substrate 1 according to the present invention. An undercoat material 2 having the following composition was continuously applied to the base material 1 by a knife coater at a coating amount of 50 g / m ² .

Composition of the undercoat material: parts by weight Silica powder (Cyroid # 244 manufactured by Fuji Davison Co., Ltd.) 10 Hydroxyl group-containing vinyl chloride / vinyl acetate copolymer 5 (Vinylite VAGH Union Carbide) Thermoplastic polyurethane elastomer 20 Dibutyl tin Dilaurate 1 (Stabilizer KS-1260 Kyodo Chemical Co., Ltd.) Triethylenediamine (Dabco) 1 Toluene 40 Ethyl acetate 40 Isopropyl alcohol 10

Then, hot air at 60 ° C. was immediately blown onto the coated surface for 60 seconds to forcibly evaporate the solvent and dry it to form a layer of the undercoat material 2.

Further, a polyurethane resin coating material 3 having the following composition was applied on the layer made of the undercoat material 2 in the same manner as described above at a coating amount of 20 g / m ² .

Composition of polyurethane resin coating: parts by weight Silica powder (Matt Agent OK-412 manufactured by Degussa) 18 Fatty acid modified polyester resin (hydroxyl group content 2%) 100 Polyisocyanate curing agent (isocyanate content 12%) 50 Toluene 50 Ethyl acetate 50 Silicon oil 1

Next, hot air at 60 ° C. was blown onto the coated surface for about 3 minutes to complete the curing reaction, and it was wound up to complete the coating process.

In the above-mentioned embodiments of the present invention, the curing of the polyurethane resin coating material is completed at a temperature of 60 ° C. in a short time of 3 minutes, and it is of course that the disadvantages due to heat such as heat deformation and heat deterioration of the base material do not occur. , Productivity has also improved. Further, since the above-mentioned polyurethane resin coating material does not contain any catalyst or additive that accelerates the curing reaction, the pot life of the coating material was extended over as long as 24 hours.

The physical properties of the obtained product are as follows. 60 ° Gloss reflectance 1% or less Scratch scars are good Alcohol rubbing test Good Gobang eyes Cellotape adhesion 1mm pitch 100/100

[0030]

As described above, according to the coating method of the present invention, the polyurethane resin coating material is rapidly cured at a low temperature of 60 ° C. in a short time of 2 minutes. In addition to solving the inconvenience caused by heat, productivity is improved, and since it is not necessary to include a catalyst or an additive that accelerates the curing reaction in the paint, the usable time of the paint is 4 to 24 hours. It is a useful method that is extended and practical.

[Brief description of drawings]

FIG. 1 is a cross-sectional view for explaining a coating method of the present invention.

[Explanation of symbols]

 1 Base material 2 Undercoat material 3 Polyurethane resin paint

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁵ Identification code Office reference number FI technical display location C08G 18/10 NFT 8620-4J 18/16 NFU 8620-4J

Claims (13)

[Claims] 1. When applying a polyurethane resin coating,
First, an undercoating material containing a compound that accelerates the curing reaction of the polyurethane resin coating material is applied on a substrate to be coated, and then a polyurethane resin coating material is applied on the undercoating material. Coating method. 2. The coating method according to claim 1, wherein the polyurethane resin coating material is a resin coating material having an isocyanate group. 3. An isocyanate group-containing polyurethane resin coating material according to claim 2, which is one of a moisture-curing polyurethane resin coating material having a terminal isocyanate group, a two-component curing type polyurethane resin coating material comprising a polyol and polyisocyanate, or a polyisocyanate blocked type. The coating method according to claim 2, which is a liquid thermosetting polyurethane resin coating material. 4. The coating method according to claim 1, wherein the compound that accelerates the curing reaction of the polyurethane resin coating is one or more selected from the group of tin compounds and amines. 5. The coating method according to claim 4, wherein the tin compound is dibutyl tin dilaurate or dibutyl tin maleate. 6. The coating method according to claim 4, wherein the amines are aliphatic tertiary amines. 7. The coating method according to claim 6, wherein the aliphatic tertiary amine is triethylenediamine. 8. The coating method according to claim 4, wherein the amines are aromatic tertiary amines. 9. The coating method according to claim 1, wherein the compound that accelerates the curing reaction of the polyurethane resin coating material is metal soap or vanadium oxide. 10. The undercoat material is further applied onto the two layers applied according to claim 1, and then a polyurethane resin paint is applied thereon, and this applying step is repeated. Item 1 The coating method. 11. The base material according to claim 1, wherein a polyurethane resin coating material is applied in advance, the undercoat material is applied on the base material, and then the polyurethane resin coating material is applied on the base material. The coating method according to claim 1. 12. The method according to claim 11, wherein the undercoat material is further applied onto the three layers applied in claim 11, and then a polyurethane resin paint is applied thereon, and the applying step is repeated. Item 11 The coating method. 13. The coating method according to claim 1, wherein the base material according to claim 1 is a plastic sheet-shaped base material.