JPH01247413A - Thermosetting covering sheet - Google Patents

Abstract

PURPOSE:To facilitate the formation of a hard film having improved flexibility and adhesion processability and excellent thermosetting characteristics and resistance to thermal shock, by compounding an acrylic polyol, a blocked isocyanate crosslinking agent, etc., a specified liq. oligomer and a heat-reactive curing agent. CONSTITUTION:A thermosetting resin compsn. obtd. by compounding 100 pts.wt acrylic polyol (A) having an MW of 1,000-100,000 and a plurality of hydroxyl groups and being solid at ordinary temp., 10-40 pts.wt. blocked isocyanate crosslinking agent prepd. by blocking the isocyanate groups of an isocyanate compd. having two or more isocyanate groups in its molecule with a blocking agent such as phenol or epsilon-caprolactam at a ratio of OH to OCN of 0.8-1.2 or a melamine resin (B), 1-300 pts.wt. oligomer (C) which is liq. at ordinary temp., such as an oligomer (a) having an MW of 3,000 and acryloyl groups at its molecular terminals and/or an acrylic polyol oligomer (b) and an appropriate amt. of a heat-reactive curing agent corresponding to the component C (e.g., 2-15 pts.wt. amine curing agent) is made into a sheet to obtain the title sheet in an uncured state.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to a thermosetting coating sheet that is coated on an article and then thermally cured to form a uniform hardened coating on the article. The present invention relates to a thermosetting coating sheet that is flexible and can be easily coated, and can form a hard coating with excellent impact resistance after curing.

(Prior Art) Paints have generally been used to coat plastic molded bodies, metal molded bodies, etc. for the purpose of improving their appearance and preventing corrosion, or for various markings.

However, when painting with paint, it is necessary to adjust the viscosity and concentration of the paint, making the process complicated. Paints using organic solvents cause contamination of the working environment and health and safety problems. Water-based solvent-based paints require a long time to dry, require drying equipment to dry quickly, and require a lot of energy such as heating and blowing air. There are drawbacks.

In order to solve these problems, sheet-like coating materials have been proposed in place of paint. for example.

A sheet-like coating material mainly made of polyvinyl chloride is used. Such a sheet material does not contaminate the work environment or cause health and safety problems, and does not require drying after application, which simplifies the work. However, since the main component of the material is soft polyvinyl chloride, the resulting coating has poor impact resistance and is prone to cracking.

As an alternative to these soft polyvinyl chloride sheet materials, heat or photo-curable sheet materials have been proposed. This sheet material hardens to form a hard coating when heated or irradiated with light, either during or after the attachment of the article.

For example, Japanese Patent Publication No. 57-13425 discloses a thermosetting composite sheet having a laminated structure of a layer containing a direactive unsaturated polymer, an oligomer, a 7-mer, etc., and a layer containing a radical reaction initiator. has been done. However, in such sheet materials, since the component that causes the double polymerization reaction and the single reaction initiator are contained in different layers, it is difficult to control heating and pressure during curing, and therefore it is difficult to obtain a uniformly cured film. I can't get it. Furthermore, since paper, woven fabric, non-woven fabric, etc. are used as the sheet-like base material impregnated with the radical reaction initiator, it is possible to apply the product while stretching it, for example, when coating an article with uneven or curved surfaces. There are drawbacks such as difficulty and failure to obtain a good cured film.

(Problems to be Solved by the Invention) The present invention solves the above-mentioned conventional problems, and aims to provide flexibility before curing, easy coating operation, and uniform coating. It is an object of the present invention to provide a thermosetting coating sheet capable of forming a hard film with excellent impact resistance.

(Means for Solving the Problems) The thermosetting coating sheet of the present invention is an uncured sheet made of a thermosetting resin composition.

The thermosetting resin composition includes (a) an acrylic polyol that is solid at room temperature; (a) blocked isocyanate-1 crosslinking agent or melamine resin; (C) an epoxy resin oligomer having an acryloyl group at the molecular end. The main components are at least one oligomer that is liquid at normal temperature selected from the group of oligomers consisting of oligomers and acrylic polyol oligomers; and (d) a heat-reactive curing agent.

The thermosetting coating sheet of the present invention [・represents 5 the above acid content (=1)
.

It is composed of a thermosetting resin composition containing (b), (C) and (d) as main components, and is uncured at a temperature lower than the curing temperature of the acrylic polyol (a) and oligomer (C) contained therein. It is in the form of a highly flexible solid or solid solution.

Acrylic polyol (a) contained in the above resin composition
is an acrylic polymer having multiple hydroxyl groups,
It is a solid polymer at room temperature. Its molecular weight is i, o
A range of oo to 100,000 is preferred. Such polymers can be obtained by copolymerizing two, for example, a (meth)acrylic acid alkyl ester monomer and a (meth)acrylic acid ester monomer having a hydroxyl group such as 2-hydroxyethyl (meth)acrylate. . A thermosetting resin composition containing an acrylic polyol having the above properties is
When formed into a coating sheet, it has the necessary viscosity properties to retain its shape during storage and use.

In other words, a thermosetting coating sheet made of a thermosetting resin composition has flexibility before curing and is hard enough to maintain its sheet shape. Furthermore, the hydroxyl value (reflecting the number of hydroxyl groups contained) of the acrylic polyol is preferably 7 or in the range of 30 to 250. When the hydroxyl value is less than 30, the number of hydroxyl groups that can cause a crosslinking reaction during curing is small, and therefore a sufficiently hard coating cannot be obtained after curing. When the hydroxyl value exceeds 250,
The crosslinking density becomes high and a good hardness film cannot be formed.

In order to cure the acrylic polyol, a one-block isocyanate crosslinking agent or a melamine resin (t)) is used as a heat-reactive curing agent. Here, the term "blocked isocyanate crosslinking agent" refers to a compound in which the isocyanate groups of an isocyanate compound having two or more inocyanate groups in one molecule are blocked with a blocking agent such as phenol, oxime, ε-caprolactam, or malonic acid ester.

Examples of the above-mentioned isocyanate compounds include tolylene diisocyanate, diphenylmethane diisocyanate, and hexamethylene diisocyanate.

Monomers such as isophorone diisocyanate, or trimethylolpropane adducts of these monomers.

Examples include isocyanurate modified products and carbodiimide modified products. Examples of melamine resins include methylated melamine resins and butylated melamine resins, which are commonly used for paints. Blocked isocyanate crosslinking agent is
It is a heat-reactive curing agent in which the blocking agent is removed by heating and the resulting isocyanate group causes a crosslinking reaction with the hydroxyl group of the acrylic polyol. This is because melamine resin can react with the hydroxyl groups of acrylic polyols at high temperatures.

This also acts as a heat-reactive curing agent. The content of the blocked isocyanate crosslinking agent is such that the ratio of the hydroxyl groups contained in the acrylic polyol to the isocyanate groups contained in the blocked isocyanate crosslinking agent is 0.8 to 1.2.
It is preferable to adjust the amount within the range of .

The melamine resin is preferably used in an amount of 10 to 40 parts by weight per 100 parts by weight of the acrylic polyol.

The oligomer (C) contained in the resin composition is as follows.

It is at least one selected from the group consisting of epoxy resin oligomers, oligomers having an acryloyl group at the molecular ends, and acrylic polyol oligomers, and is liquid at room temperature.

As the above-mentioned epoxy resin oligomer, for example, bisphenol A type, novolac type, 2g-type aliphatic type, and Changzhen aliphatic type epoxy resin oligomers are used.

Examples of the oligomer having an acryloyl group at the molecular terminal include polyhydric alcohol acrylates (eg, polyethylene glycol diacrylate).

Polypropylene glycol diacrylate, trimethylolpropane triacrylate, tetramethylolmethanetetraacrylate) 1 Epoxy acrylate ¥4
(For example, bisphenol A epoxy acrylate,
Examples include phenol novolac type epoxy acrylate), polyester acrylates, and urethane acrylates.

Moreover, the above acrylic polyol oligomer.

It is an oligomer that mainly consists of repeating acrylate units and has a hydroxyl group in its molecular chain.

Generally, a liquid material with a molecular weight of 1,000 or less is used.

Since these oligomers (C) are all liquid at room temperature, a thermosetting coating sheet made of a resin composition containing them has appropriate flexibility before curing.

The above oligomer (C) is an acrylic polyol (a)
Preferably 1 to 300 parts by weight per 100 parts by weight,
More preferably, it is added in an amount of 20 to 200 parts by weight. When the amount of oligomer (C) added decreases, the flexibility of the thermosetting coating sheet becomes poor. Conversely, when the amount increases, the viscosity decreases and fluidity increases, making it difficult to maintain the sheet shape.

The heat-reactive curing agent (d) is for curing the oligomer (C) and is appropriately selected depending on the type of oligomer (C) used. For example, oligomer (C)
When an epoxy resin oligomer is used as an epoxy resin oligomer, an amine curing agent (dicyandiamide, BP, /monoethylamine complex compound, etc.) is preferably used. These amine curing agents are epoxy resin oligomer 100! It is preferably used in a proportion of 2 to 15 parts by weight.

When using an oligomer having an acryloyl group, a high temperature decomposition type radical initiator is preferably used. Examples of the radical initiator include L-butyl hydroperoxide, cumene hydroperoxide, diisopropylbenzene hydroperoxide, di-t-butyl peroxide, t-butylcumyl peroxide, 2,5-dimethyl-2,5- There is di(L-butylperoxy)hexyne-3. These radical initiators are the oligomer 1 mentioned above.
It is preferably used in a proportion of 0.1 to 5 parts by weight per 0.00 parts by weight.

When using an acrylic polyol oligomer, the same block isocyanate crosslinking agent or melamine resin as used for the above-mentioned acrylic polyol (a) which is solid at room temperature is used. The amount is also the same as above. In other words, when an acrylic polyol oligomer is used as the oligomer (C), the same amount as above is set for the total amount of the solid acrylic polyol (a) and the oligomer (C). Ru.

These curing agents (d) start curing reactions by heating after the coating sheet is attached, so select a curing agent that has a reaction initiation temperature similar to that of the above-mentioned block isocyanate crosslinking agent or melamine resin (b). It is desirable to do so.

The thermosetting resin composition further contains a filler, if necessary.
Contains an anti-aging agent, a coloring agent, etc.

The coating sheet of the present invention has an adhesive layer 1 on one side of the thermosetting coating sheet 1, for example, as shown in FIGS. 1 to 3.
may be provided, and/or a support layer 3 may be provided on the other side.

When the thermosetting coating sheet 1 does not have sufficient adhesive strength to the article to be coated.

An adhesive layer 2 is provided on one side of the covering sheet 1, and the adhesive layer 2
By attaching it to the article through the adhesive, it is possible to improve the adhesion between the hard coating and the article after hardening.

When the thermosetting resin composition constituting the covering sheet 1 contains a large amount of oligomer (C) that is liquid at room temperature, the viscosity of the composition decreases, so that the covering sheet 1 retains its shape. It becomes difficult to do so.

In such a case, a support layer 3 is provided on one side of the covering sheet 1.
By providing this, the shape retention of the covering sheet 1 can be improved. As shown in Figure 4, the thermosetting resin sheet! The adhesive layer 2 may be provided on one side of -1, and the support layer 3 may be provided on the other side.

As described above, the adhesive layer 2 is formed to adhere the covering sheet 1 to the article when covering the article with the covering sheet 1. Therefore, it is necessary to have high adhesiveness and excellent durability in the bonded state. Adhesives for forming such an adhesive layer 2 include pressure-sensitive adhesives,
True-melt adhesives, post-curing adhesives, and the like are preferably used. Mixtures of these adhesives can also be used.

It is also possible to sequentially laminate a plurality of different types of adhesives to provide excellent adhesion to both the thermosetting coating sheet 1 and the article to be coated.

Among the above adhesives, pressure-sensitive adhesives include rubber-based, acrylic-based, urethane-based, and silicone-based adhesives. Hot-melt adhesives include, for example, ethylene-vinyl acetate copolymer systems.

Styrene-isoprene-styrene block copolymer system,
There are adhesives such as acrylic. 1 for post-curing adhesives
For example, there is a microcapsule curing adhesive. Examples of the material include uncrosslinked unsaturated polyester adhesives, self-crosslinked acrylic adhesives, and the like.

Further, the support layer 3 is formed to improve the shape retention of the covering sheet 1 during storage and use. The covering sheet 1 is attached to an article by stretching it as necessary. Therefore, the support layer 3 is preferably composed of a film that is malleable at least under heating (for example, a thermoplastic resin film or a rubber film). Examples of the thermoplastic resin include soft polyvinyl chloride, polyurethane, acrylic resin, polyester, ethylene-vinyl acetate copolymer, polyethylene, and polypropylene. Examples of materials for the rubber film include natural rubber, styrene-butadiene rubber, and nitrile-butadiene rubber.

Isoprene rubber, butadiene rubber, chloroprene rubber,
Examples include urethane rubber, silicone rubber, and acrylic rubber. Mixtures of these thermoplastic resins and rubbers can also be used. or.

These can also be laminated to form a film layer. Thermoplastic resin films often become malleable under heating, but if a rubber film is used.

Spreadability can be obtained even at room temperature.

The adhesive layer 2 and the support layer 3 further contain a filler, an anti-aging agent, a colorant, and the like, if necessary.

The coating sheet of the present invention is prepared, for example, as follows. First, (a) acrylic polyol, (2) blocked isocyanate crosslinking agent or melamine resin.

(C) Oligomer, (d) heat-reactive curing agent, and if necessary, a suitable organic solvent are mixed. The above-mentioned acrylic polyol and the like are often commercially available as an organic solvent solution, and in that case, the above-mentioned organic solvent is not required. The resulting mixture is applied to the surface of a release-treated base material such as a film, and then dried.

A thermosetting coating sheet 1 is obtained by peeling the formed sheet from the base material. Thermosetting coating sheet 1
The thickness of typically ranges from 10 to 500 μm.

Any method can be used to laminate the adhesive layer 2, but for example, a thermosetting coating sheet 1 is prepared on a releasable base material in the same manner as described above.9.

A solution containing the above adhesive is applied to the surface of a different releasable base material and heated and dried to form an adhesive layer 2, and the thus obtained thermosetting coating sheet and adhesive The agent layers 2 are pressed against each other by applying pressure using a roll press, for example, and the releasable base material is removed.

A sheet for lamination is prepared. What is the thickness of adhesive layer 2?

It is typically in the range of 30-100 μm.

For the support layer 3, the above-mentioned base material may be used as is, or after forming the covering sheet 1, the above-mentioned thermoplastic resin film or rubber film constituting the support layer 3 may be laminated. The layer thickness of the support layer 3 is typically 10 to 50011 m.

The thermosetting coating sheet of the present invention can be used, for example, in the following manner to form a hard coating on a desired article. Since the covering sheet has a certain degree of flexibility at room temperature, it can be stretched without heating and attached to the surface of the article according to its shape. Next, at least the applied portion of the article to which the covering sheet is applied is heated to a temperature higher than the curing temperature of the acrylic polyol and oligomer contained in the sheet to completely cure the covering sheet. In this way, a hard coating is formed on the surface of the article. Alternatively, the covering sheet may be cured at the same time as the covering sheet is applied to the article by hot pressing using a mold that fits the article. According to such a method, even a three-dimensional object with unevenness can be easily coated.

Even when the above-mentioned thermosetting coating sheet has poor adhesion to the article to be coated, if a sheet having the adhesive layer 2 is used, sufficient adhesion to the article can be obtained.

Even when the thermosetting coating sheet is in the form of a solid solution, the sheet having the support layer 3 can be used when the sheet is attached to or heated on the surface of the article.

This prevents the shape of the sheet from deforming more than necessary. When attaching the sheet having the support layer 3, heating is performed as necessary to impart flexibility to the support layer 3 and ensure desired malleability. After the covering sheet is applied to the article and cured by heating, the support layer 3 may be peeled off and removed.

(Example) Examples of the present invention will be described below. In addition.

Hereinafter, "part" means 1 part by weight.

Fruit blind group (8) Preparation of thermosetting coating sheet: 100 parts of thermosetting acrylic polyol (manufactured by Nippon Shokubai ■, Arotan 2060°, solid content 60% by weight, hydroxyl value 48); Blocked isocyanate crosslinking agent (Takeda) (manufactured by Yakuhin Kogyo ■, Takenate B-815N, solid content 60% by weight) 49 parts (this crosslinking agent has an isocyanate group equivalent to the hydroxyl group of the above-mentioned acrylic polyol); As an epoxy resin oligomer, 49 parts
Functional epoxy resin (manufactured by Mitsubishi Gas Chemical, Tetrad)
D) 25 parts and bisphenol A type epoxy resin (manufactured by Yuka Shell Epoxy ■).

25 parts of Epikote 828); and 5 parts of dicyandiamide were mixed with stirring. This mixture was applied to a polyurethane film (thickness: 50 μm) treated with silicone mold release.
The mixture was coated on the release surface of the mold and dried at 80°C for 5 minutes to prepare an uncured coating sheet. The layer thickness of the obtained coating sheet was approximately 50 μm.

(B) Performance evaluation of thermosetting coating sheet: A strip-shaped test piece (20×1
00 am) was cut and subjected to a tensile test in the longitudinal direction at 80'C. Even when stretched to 200%, no cracks or cracks occurred, and uniform elongation was exhibited.

Next, a coating test was conducted on the above-mentioned coating sheet.

A coating seam 1-(
20×20c+n) was stretched at 80°C, and the resin layers were pressure-bonded with their resin layers facing each other. Without wrinkles,
Good coverage was achieved. Next, this coated steel plate was heated at 160°C for 30 minutes to harden the acrylic polyol and oligomer, and then the polyurethane film was peeled off to form a strong coating (approximately 40 μm thick).
I got it. The pencil hardness of the coating was 2H.

(Effects of the Invention) When the thermosetting coating sheet of the present invention is used, a hard coating having excellent thermosetting properties, uniformity, and excellent impact resistance can be easily formed. This is because the thermosetting resin contained in the sheet is in an uncured state and the sheet contains an oligomer that is liquid at room temperature.

This sheet is flexible at room temperature or at least below the curing temperature. Therefore, it has excellent application workability and can easily form a uniform hard film even on a three-dimensional object having irregularities. Such coating sheets 1 to 1 are used in a wide range of applications, such as sheet materials for decoration or display that are attached to the surfaces of furniture, plastic molded bodies, steel plates, and the like.

A-'' Ωl+'i1, my friend.

1 to 3 are cross-sectional views showing an example of the thermosetting coating sheet of the present invention.

1... Thermosetting coating sheet, 2... Adhesive layer, 3
...Supporting layer.

that's all

Claims (1)

[Claims] 1. (a) Acrylic polyol that is solid at room temperature; (b) Blocked isocyanate crosslinking agent or melamine resin; (c) Epoxy resin oligomer, oligomer having an acryloyl group at the molecular end, and acrylic polyol oligomer At least one oligomer selected from the group consisting of oligomers that is liquid at room temperature; and (d) a thermosetting resin composition containing a heat-reactive curing agent as a main component, characterized in that it is in an uncured state. Thermosetting coating sheet.