JPH04142376A - Mar-resistant coating composition curable by actinic radiation - Google Patents

Abstract

PURPOSE:To obtain a coating composition which cures readily by irradiation with actinic radiation, is excellent in marring resistance and workability, and forms a film excellent in heat resistance, boiling water resistance, solvent resistance, and adhesiveness to various base materials, by mixing a plurality of specified acrylate derivative components at a specified ratio. CONSTITUTION:The title composition contains as film-forming component an acrylate mixture consisting of 10-60wt.% reaction product of a diisocyanate compound with pentaerythritol triacrylate, 20-60wt.% polyfunctional polyester acrylate obtained by co-esterifying a polyhydric alcohol component comprising a dihydric alcohol and an alcohol having at least three hydroxyl groups in the molecule with a dicarboxylic acid and acrylic acid, and 10-60wt.% difunctional monomer of the formula (wherein m and n are each 0 to 5, provided that m + n <=15). This composition readily cures by irradiation with actinic radiation, has good adhesiveness to a molding, sheet, and film of various synthetic resins, and can form a coating film excellent in marring resistance, solvent resistance, and workability.

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Field of Industrial Application The present invention relates to an active energy ray-curable scratch-resistant coating composition. More specifically, it can be easily cured by irradiation with active energy rays, and can form a film that has good adhesion to various synthetic resin molded products, sheets, and films, and has excellent scratch resistance, solvent resistance, and processability. The present invention relates to coating compositions.

(b) Prior Art Generally, resin molded products are used in a wide range of fields because they are lightweight, have excellent impact resistance, are inexpensive, and are easy to mold. However, since the surface hardness is lower than that of metal or glass, the surface may be scratched due to contact with other items during storage, transportation, or use, which may impair the beauty and transparency of the molded product and significantly reduce its value as a product. There is a need to improve the surface scratch resistance, as this may cause the scratches to deteriorate and become unusable.

Various studies have been carried out in the past in order to improve these drawbacks. For example, organic coating materials such as melamine wood grains, or inorganic coating materials such as organopolynoloxane coatings are applied and heated. There is a way to harden it. However, all of these methods have problems with workability, and organic coatings have insufficient scratch resistance, and inorganic coatings have poor adhesion and require brimer treatment. had.

On the other hand, the method of applying a polyfunctional acrylate monomer to the surface of a resin molded product and irradiating it with active energy rays to form a cured film has excellent productivity and has excellent scratch resistance and adhesion. Therefore, many studies and proposals have been made (Japanese Patent Publications No. 48-42211, No. 49-22).
Publication No. 951).

(c) Problems to be Solved by the Invention As the uses of resin molded products have diversified in recent years, there has been an increase in the number of uses in which both abrasion resistance and workability are emphasized in the coating. In particular, in the case of thin plate molded products, workability such as punching and heat bending is required. It is extremely difficult to obtain a coating with excellent scratch resistance and processability, and at present no coating material that is satisfactory for this purpose has been obtained.

The present invention was made under such circumstances, and it is an object of the present invention to provide a new active energy ray-curable coating material that is particularly excellent in processability and scratch resistance after curing.

(d) Means and effect for solving the problem As a result of intensive research, the present inventors have found that an acrylate-based coating material composition containing a plurality of specific acrylate derivative components in a specific ratio is resistant to active energy rays. It was discovered that it cures easily and forms a film that has excellent scratch resistance and processability, as well as excellent heat resistance, boiling water resistance, solvent resistance, and adhesion to various substrates, and completed the present invention. reached.

Thus, according to the present invention, (a) a reaction product of a Neuson abut compound and pentaerythritol triacrylate: 10 to 60% by weight; (b) a dihydric alcohol as a polyhydric alcohol component; Multifunctional polyester acrylate obtained by coesterifying an alcohol having three or more hydroxyl groups with a dicarboxylic acid and acrylic acid: 20-60% by weight, (c) Bifunctional monomer shown by the following - double weight ([) Body/10-60% by weight C■.

(In the formula, m and n are each integers from 0 to 5. m+n≦
10) as a film-forming component.

The coating composition of the present invention comprises components (a), (b) and (C)
[However, (a) + (b) + (c) = 100% by weight] The above acrylate mixture (A) is mixed with an organic solvent (A) that can dissolve the acrylate mixture (A) as necessary.
B) and a photopolymerization initiator (C) are mixed together. Usually, 0 to 500 parts by weight of the organic solvent (B) is added to 100 parts by weight of the acrylate mixture (A). 1 part by weight, and 0 to 10 parts by weight of the photopolymerization initiator (C) is suitable.

The reaction product of pentaerythritol triacrylate and diisocyanate compound used in the present invention (
The material a) has very good resistance to scratches due to irradiation with active energy rays, and its cured film has both extremely excellent scratch resistance and relatively good workability. Pentaerythritol triacrylate is usually commercially available as a mixture with tetraacrylate, but there is no need to separate it, and the mixture can be used as it is.

Examples of the noisocyanate compound include hexamethylene diisocyanate, isophorone diisocyanate, quinrylene noisonoanate, tolylene diisocyanate, diphenylmethane diisocyanate, and tetramethylquinrylene noisocyanate. The appropriate amount of diisocyanate compound to be used is -NGO10 based on the remaining OH groups of pentaerythritol triacrylate.
The H equivalent ratio is in the range of 01-10, preferably 0.2-08.

The isonoanate compound is contained in pentaerythritol triacrylate. It reacts with other groups to form urethane acrylate. The reaction product (a) is used in an amount of 10 to 60% by weight, preferably 20 to 50% by weight, based on 100 parts by weight of the acrylate mixture (A). Usage amount is 10
If it is less than 60%, sufficient scratch resistance cannot be obtained;
If it exceeds , the workability is not sufficient.

The polyfunctional polyester acrylate (b) used in the present invention provides the cured film with extremely good processability, adhesion and relatively good scratch resistance.

In the raw materials for polyester acrylate, examples of dicarboxylic acids include aromatic dicarboxylic acids such as phthalic acid, isophthalic acid, and terephthalic acid, and aliphatic dicarboxylic acids such as succinic acid, maleic acid, adipic acid, sebacic acid, and azelaic acid. One type or a mixture of two or more of these dicarboxylic acids may be used.

Examples of dihydric alcohols among the polyhydric alcohol components include ethylene glycol, propylene glycol, diethylene glycol, dipropylene glycol, triethylene glycol, tetraethylene glycol, and tripropylene glycol.

Examples of alcohols having three or more hydroxyl groups in one molecule used in combination include glycerin, diglycerin, trimethylolethane, ditrimethylolethane, trimethylolpropane, ditrimethylolpropane, pentaerythritol, nventaerythritol, and tripentaerythritol. etc. can be mentioned.

These dihydric alcohols and alcohols having three or more hydroxyl groups in one molecule may be used alone or in combination of two or more.

By using polyfunctional polyester acrylate obtained by coesterifying these dicarboxylic acids and acrylic acids with the above-mentioned polyhydric alcohol, it is highly curable by ultraviolet irradiation in the air, without reducing the abrasion resistance of the crosslinked cured film. In addition, processability and adhesion to the substrate can be improved.

The molar ratio of dicarboxylic acid, acrylic acid, and polyhydric alcohol used when synthesizing the above-mentioned polyfunctional polyester acrylate (b) is adjusted as appropriate depending on the physical properties required for the cured film of the product, but basically is the dicarboxylic acid constituting the polyester acrylate and - in the acrylic acid.
It is preferable to adjust the amount of Cool (and -OH in the polyhydric alcohol) to be equal.

The amount of polyester acrylate (b) used is in the range of 20 to 60% by weight, preferably 30 to 50% by weight based on 100% by weight of the acrylate mixture (A).

If the amount used is less than 20% by weight, processability will be poor, and if it exceeds 60% by weight, the scratch resistance will decrease, which is not preferable.

The bifunctional monomer (c) represented by the general formula (1) used in the present invention improves the adhesion of the cured film to the substrate, and also imparts processability without reducing scratch resistance. . - It is not preferable for m and n to exceed 5 in terms of weight loss ([), since this lowers the scratch resistance and the curing speed. Examples of difunctional monomers include 22-his(4-acryloxyphenyl)propane, 2,2-his(4-acryloquinoethoquinophenyl)propane, 2,2-bis(
Examples include 4-acryloxyshedquin phenyl)propane, and these may be used alone or in combination of two or more.

The amount of bifunctional monomer used is acrylate mixture (
A) 10 to 60% by weight out of 100% by weight, preferably 20% by weight
-50% by weight. If the usage is less than 20%,
Adhesion and processability are not sufficient, and if it exceeds 60%, it is not preferable because it leads to a decrease in scratch resistance and curing speed.

Organic solvents (B) optionally used in the present invention include alcohols such as ethanol, isopropanol, normal propazol, normal butanol, and isobutanol; aromatic hydrocarbons such as toluene and kiln; ethyl acetate; , butyl acetate, amyl acetate, ethyl lactate, etc.; ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, noclohexanone, diacetone alcohol; ethers such as methyl cellosolve, ethyl cellosolve, butyl cellosolve; However, two or more of these types may be used in combination. The organic solvent is used to further improve the coating workability of the coating composition and the adhesion of the cured film to the substrate. The amount used is the acrylate mixture (A)
It is used in a range of 0 to 500 parts by weight per 100 parts by weight. The type and amount may be adjusted as appropriate depending on the coating method and the like.

In the present invention, in order to apply the coating composition to the surface of the resin molding and form a cured film, ultraviolet rays, electron beams,
Is it necessary to irradiate active energy rays such as radiation?

Among these methods, the method of irradiating ultraviolet rays is the most practical because the equipment is simple and other reasons.

During the first step of curing by irradiating ultraviolet rays, it is necessary to add a photopolymerization initiator that can initiate a polymerization reaction upon irradiation with ultraviolet rays. Photopolymerization initiator (C) used in the present invention
For example, benzoin ethers such as hengeine ethyl ether and hengeine isobutyl ether; hennorketals such as dimethquine phenylacetophenone and hydroquinone chlorhequine phenyl ketone; acetophenones such as jetoxyacetophenone;
Examples include benzophenones, hensyls, and thioxanthones, and these may be used alone or in combination of two or more. These photoinitiators (C
) is used in an amount of 0 to 10 parts by weight, preferably 0.1 to 6 parts by weight, based on 100 parts by weight of the acrylate mixture (A). If the amount of photopolymerization initiator used exceeds 10 parts by weight, it is not preferable because the abrasion resistance and weather resistance of the coating will decrease.

The coating composition of the present invention preferably contains the acrylate mixture (A), the organic solvent (B), and the photopolymerization initiator (C) in the above-mentioned amounts, provided that the effects of the present invention are not impaired. Furthermore, various additives such as ultraviolet absorbers and surfactants may be contained.

UV absorbers are used here to provide stability and weather resistance to the coating composition. Generally, the coating composition is handled under illumination such as a fluorescent lamp, so there is a possibility that it will be exposed to visible light including trace amounts of ultraviolet light. Therefore, by adding an ultraviolet absorber, it is possible to suppress the polymerization reaction of the coating composition caused by these rays. Furthermore, molded articles coated with the coating composition may be used outdoors and are required to have weather resistance. Therefore, one preferred embodiment is to add a UV absorber to the coating composition.

Further, a surfactant is appropriately used to provide excellent surface smoothness during coating. Such surfactants include:
There are silicone-based, fluorine-based, alkyl-based, etc., and the type and amount thereof may be appropriately selected depending on the coating method and the like.

Furthermore, in addition to the above additives, leveling agents, antioxidants, hindered amine light stabilizers, plasticizers,
Additives such as antifoaming agents, antistatic agents, and fillers may be added.

Resin molded products to which the coating composition of the present invention can be applied include:
Various resins, both thermoplastic and thermosetting resins, such as polymethyl methacrylate resin, polystyrene resin,
Examples include sheet-like and film-like molded products made from AS resin, ABS resin, polycarbonate resin, hard vinyl chloride resin, etc. In particular, they have excellent scratch resistance as well as punching, which has been insufficient in the past. It can now be applied to applications that require workability such as heat bending.

In addition, as a method for applying the coating composition to the resin molded article,
Commonly used methods such as dipping coating, roll coating, spray coating, flow coating, and flow coater coating can be employed as appropriate.

(B) Examples Hereinafter, embodiments of the present invention will be explained in detail using Examples, but the present invention is not limited to the Examples below. In addition, evaluation in Examples was performed by the following method.

(1) Scratch resistance: Using an abrasion resistance tester (manufactured by Yasuda Seiki Seisakusho), the surface of the test piece was observed after #000 steel wool was moved back and forth 100 times under a load of 1004'/cm'.

○ Almost no scratches △ Slight scratches × Significant scratches (2) Workability: After forming a cured film on a polycarbonate resin sheet with a thickness of 10 mm, a sheet with a length of 102' and a width of 51' is formed. A test piece cut into a strip with a diameter of 20. The state of the coating was observed by wrapping it around the outer circumference of the cylinder.

O No abnormalities △ Slight cracks occurred × Many cracks occurred (3) Adhesion: The surface of the test piece was cut with a cutter knife at 111
．． LoXIO squares were cut at intervals, a polyester adhesive tape was pressed, and then peeled off to measure the residual rate of the cured film.

0 100/100 △　51/　100～99/　100 X　O/loo~50/to.

(4) Boiling water resistance, after immersion in boiling water for 2 hours (3)
Adhesion was evaluated using the same method.

Examples 1-3 Various coating compositions (Examples 1-3,
Comparative Examples 1 to 6) were prepared.

In Table 1, component (i)-1 is 5 of pentaerythritol triacrylate and tolylene diisocyanate.
: 1 mol reaction product, 5:1 mol reaction product of pentaerythritol triacrylate and isophorone diisocyanate as component (a)-2, component (b,)
-1 is a polyester acrylate oligomer (average molecular weight 150
Component (b)-2 is a polyester acrylate oligomer (average molecular weight 980) made by reacting terephthalic acid, maleic acid, and acrylic acid as complex acid components and propylene glycol and trimethylolpropane as complex polyhydric alcohol components. , and bisphenol A diethylene oxide diacrylate was used as component (C).

Irgacure 184 manufactured by Ciba Geigy was used as a photopolymerization initiator, Tinuvin 900 was used as an ultraviolet absorber, and BYK 306 manufactured by BYKCHEMIE was used as a leveling agent.

Each of these coating compositions was applied to a 2' thick polycarbonate resin plate (Takiron Polycarbonate Note #1600).
The film was coated using a bar coater so that the film thickness after curing would be about 10 μm, and dried at 60° C. for 5 minutes to evaporate the solvent. After that, a high-pressure mercury lamp (HL-6OL manufactured by Nippon Battery) was used.
), irradiation was performed once in an air atmosphere at an irradiation distance of 15:' and a conveyor speed of 2 m/min. Table 1 shows these results.
It is also shown in .

As is clear from Table 1, only when the coating composition of the present invention satisfies the conditions, a coating having excellent scratch resistance and processability, as well as excellent boiling water resistance and adhesion, can be formed. I understand.

(F) Effects of the Invention The coating composition of the present invention is easily cured by irradiation with active energy rays, has good adhesion to various synthetic resin imaging products, sheets, and films, and has scratch resistance and solvent resistance. Forms a coating with excellent workability as well as excellent workability. Therefore, resin molded products using such coating compositions have excellent scratch resistance, especially workability, and can be used as covers for windows, lenses, watches and instruments, etc.
Especially when punching out lighting equipment covers, windshields, nameplates, etc.
It can be suitably used in applications requiring workability such as heat bending.

Claims (1)

[Claims] 1. (a) Reaction product of diisocyanate compound and pentaerythritol triacrylate: 10 to 60% by weight, (b) Dihydric alcohol as a polyhydric alcohol component, and 3% by weight per molecule. Polyfunctional polyester acrylate obtained by co-esterifying an alcohol having 1 or more hydroxyl groups with dicarboxylic acid and acrylic acid: 20-60% by weight
, (c) Bifunctional monomer represented by the following general formula (I): 1
0 to 60% by weight ▲There are mathematical formulas, chemical formulas, tables, etc.▼...(I) (In the formula, m and n are each % numbers from 0 to 5, and m+n≦
10) as a film-forming component. 2. The coating composition according to claim 1, comprising an organic solvent capable of dissolving the acrylate mixture. 3. The coating composition according to claim 1 or 2, comprising a photopolymerization initiator.