JP2860779B2 - Composition for coating - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a coating composition having excellent scratch resistance. For more information,
The present invention relates to an overcoat agent for coating the surface of a plastic sheet or film, or a printed product thereof.

[0002]

2. Description of the Related Art Conventionally, thermosetting resins and ionizing radiation-curable resins have been used as overcoating agents for covering the surface of paper, plastic sheets or films and their printed ones to protect them from scratches and scratches. Reactive resins such as reactive resins have been used.

[0003]

However, in order to prevent scratches due to friction and scratching, it is necessary to harden the resin to be coated, and therefore it was necessary to reduce the average molecular weight between crosslinks. As a result, there is a disadvantage that the flexibility of the resin itself is reduced and the film is cracked when the substrate is bent.

[0004]

Means for Solving the Problems The present inventors have conducted intensive studies on an overcoating agent which is hard to be scratched and a flexible film can be obtained, and as a result, spherical particles having an average particle size specified for a reactive resin. , A certain amount of effect can be obtained by adding a certain amount, but that alone is not sufficient, and it is necessary to specify the relationship between the average thickness of the coating layer and the average particle size of the spherical particles. It has been found that a sufficient effect can be obtained when the constitutional requirements are satisfied, and the present invention has been achieved. That is, the present invention provides a Knoop hardness of 130
0 kg / mm ² or more, spherical particles with an average particle size of 3 to 50 μm
Consists aircraft particles (A1) and the reactive resin (B), the total amount of the content of the (A1) is the (A1) (B) 5
-30% by weight, and the average particle size d of the ( A1 ) is d (μm).
Is a coating composition characterized by satisfying the following formula (1). 0.3t ≦ d ≦ 2.0t (1) [where t is the average film thickness (μm) of the coating layer. The present invention also provides a spherical particle having an average particle diameter of 3 to 50 μm.
(A) and ionizing radiation-curable reactive resin (B1)
And the content of (A) is the total amount of (A) and (B1)
5 to 30% by weight with respect to the average particle diameter d of (A)
(Μm) satisfies the above expression (1).
It is a coating composition .

(A) used in the present invention has a spherical shape or a similar shape. As the (A), fused alumina, Bayer method alumina, zirconia, titania or a eutectic mixture of these having a Knoop hardness of 1300
kg / mm ² or more of spherical inorganic particles (A1) . Of these, those having a Knoop hardness of 18
It is at least 00 kg / mm ² , and specific examples include fused alumina.

[0006] The Knoop hardness mentioned here is a minute indentation hardness measured using a Knoop indenter, and the load when a diamond-shaped indentation is formed on the test surface is determined from the length of the longer diagonal line of the permanent dent. It is a value represented by the quotient divided by the projected area of the dent. This test method is described in ASTM C-849.

[0007] As a method for making the shape of the inorganic particles spherical, a method in which the above-mentioned irregularly shaped inorganic material is put into a high-temperature furnace having a melting point or higher and melted to make it spherical by utilizing surface tension; A method in which the material melted at the above high temperature is blown out into a mist to form a sphere, and the like.

[0008] The content of (A) in the composition of the present invention is usually 5 to 30% by weight, preferably 5 to 25% by weight, particularly preferably 5 to 15% by weight.

When the content of (A) is less than 5%, the scratch resistance becomes insufficient, and when it exceeds 30% by weight, the reactive resin (B)
The binder effect is impaired, and adverse effects such as a decrease in flexibility are caused.

The average particle size of (A) is usually 3 to 50 μm,
Preferably, it is 8 to 40 μm. If the average particle size is less than 3 μm, the film becomes opaque, which is not preferable. On the other hand, when the average particle size exceeds 50 μm, the thickness becomes too large than the thickness of the coating agent usually used, so that the surface smoothness of the coating deteriorates.

When the composition of the present invention is coated on a substrate, the film thickness and the average particle diameter d are represented by the following formula (1).
Must be satisfied. 0.3t ≦ d ≦ 2.0t (1) [where t is the average thickness (μm) of the coating layer] When the average particle size exceeds 2.0 t, the particles protrude from the surface of the coating layer, The appearance of the coating layer deteriorates, and if it is less than 0.3 t, the scratch resistance of the coating layer deteriorates, which is not preferable.

As the reactive resin (B) used in the present invention, a thermosetting resin and an ionizing radiation-curable resin (B1) can be used.

The thermosetting resin used in (B) may be a known one, and examples thereof include a two-part urethane resin, an epoxy resin, an alkyd resin, and an unsaturated polyester resin.

As the two-part type urethane resin, a first liquid composed of a polyol compound having an average of two or more hydroxyl groups in its molecular structure, and a second liquid composed of a polyisocyanate compound are prepared by adding an equivalent of hydroxyl group to isocyanate group. What blended so that a ratio might be 0.7-1.5 is mentioned.

As the epoxy resin, an epoxy resin having an average of two or more epoxy groups in its molecular structure;
The ratio of the epoxy equivalent of the epoxy resin to the mono- or polyamine active hydrogen equivalent of 0.7 to 1.5 with the mono- or poly-amine having three or more active hydrogens in one molecule which reacts with the epoxy group. One that is blended so as to be included.

Examples of the ionizing radiation-curable resin used in (B) include compounds having one or more radical polymerizable double bonds in the molecular structure. Specific examples thereof include an unsaturated polyester resin and a (meth) acryloyl group. [Monofunctional (meth) acrylic ester, polyfunctional (meth) acrylic ester, urethane (meth) acrylate, polyester (meth) acrylate, epoxy (meth) acrylate, etc.], vinyl compound [styrene, divinylbenzene, etc.], Allyl compounds [such as diallyl phthalate] and mixtures of two or more of these.

More preferred as the reactive resin (B) in the present invention is an ionizing radiation-curable resin, and particularly preferred is a polyether-based urethane (meth) acrylate represented by the following general formula (2). is there. ^{_{CH 2 = C (R 1)}} -COOCH 2 CH 2 -OCONH-X-NHCOO - [- CH (R 2) - (CH 2) n -O-] m -CONH-X-NHCOO -CH 2 CH 2 OCOC (R ¹ ) = CH ₂ (2) (wherein, R ¹ and R ² are each hydrogen or a methyl group, X is a diisocyanate residue, n is an integer of 1 to 3, m
Is an integer of 6 to 60. )

As the diisocyanate used for the polyether-based urethane (meth) acrylate, known diisocyanates can be used. Specific examples thereof include isophorone diisocyanate, dicyclohexylmethane diisocyanate, hexamethylene diisocyanate, diphenylmethane diisocyanate, and tolylene diisocyanate.

Examples of the polyether diol used for producing the above polyether-based urethane (meth) acrylate include polyoxypropylene glycol, polyoxyethylene glycol, and polyoxytetramethylene glycol having a molecular weight of 500 to 3,000. .

The reactive resin (B) is represented by the above general formula (2)
When using the polyether-based urethane (meth) acrylate shown in (1), the amount used is 10% by weight based on the total amount of (B).
That is all. If the amount is less than 10% by weight, the flexibility of the resin itself is reduced, and the film may crack when the substrate is bent.

In the present invention, the solubility parameter (SP value) of the reactive resin (B) is usually from 9.7 to 11.0, preferably from 9.9 to 10.5. If the SP value is less than 9.7, the adhesiveness to (A) is insufficient, so that the spherical particles lack the holding power and the abrasion resistance may be insufficient.
If the P value exceeds 11.0, there is a possibility that the adhesion to the substrate may be insufficient when the substrate is coated with a paper, plastic sheet or film.

The SP value here is calculated according to "Polymer Engineering and Science, Vol. 14, p. 174 (1974)". (B) is 2
In the case of a mixture of two or more compounds, the S
It is a weighted average of P values.

When the composition of the present invention is cured by irradiation with ionizing radiation, examples of the ionizing radiation include ultraviolet rays and electron beams.

In the case of curing with ultraviolet light, a known ultraviolet irradiation device equipped with a high-pressure mercury lamp, a metal halide lamp or the like can be used. The irradiation amount of the ultraviolet ray at the time of curing is preferably 50 to 1,000 mJ / cm ² .
The amount of irradiation curing is insufficient at less than 50 mJ / cm ^2, the coating film was cured exceeds 1,000 mJ / cm ² there is a possibility of yellowing degradation.

In the case of curing with an electron beam, a known electron beam irradiation device can be used. The irradiation amount of the electron beam is preferably 1 to 10 Mrad. If the irradiation amount is less than 1 Mrad, curing is insufficient, and if it exceeds 10 Mrad, the cured coating film or substrate (paper, plastic sheet, film, etc.) may be damaged and deteriorated.

In the present invention, the average molecular weight between crosslinks after the reaction of the reactive resin (B) is usually from 150 to 1,000.
0, preferably 200 to 1,000, particularly preferably 2
50 to 800. If the average molecular weight between crosslinks is less than 150, the flexibility of the resin itself decreases, and the film may crack when the substrate is bent. If it exceeds 1,000, the resin itself becomes too soft and retains spherical particles. Due to lack of force, scratch resistance becomes insufficient.

The average molecular weight between crosslinks as used herein means m / [2 × (f−1)], where f is the average number of polymerizable functional groups of the reactive resin (B) and m is the average molecular weight. Is the value represented by

In order to use the composition of the present invention for coating, it is preferable that the viscosity is low from the viewpoint of workability. The viscosity at the temperature at which it is used for coating is preferably less than 800 centipoise, more preferably less than 500 centipoise. If the viscosity exceeds 800 centipoise, workability will be poor and a smooth coated surface may not be obtained.

In coating the composition of the present invention, the reactive resin (B) is dissolved to adjust the viscosity,
One or more solvents having a boiling point at normal pressure of 70 ° C. to 150 ° C. can be used in an amount of 30% by weight or less based on the total amount of (A) and (B). 30% by weight of solvent used
If it exceeds 300, drying takes a long time and the production speed is reduced, which is not preferable.

As the solvent, those which are usually used for paints, inks and the like can be used. Specific examples include aromatic hydrocarbons such as toluene and xylene, and ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone and cyclohexanone. Acetic acid esters such as ethyl acetate, isopropyl acetate and amyl acetate; alcohols such as methyl alcohol, ethyl alcohol and isopropyl alcohol; ethers such as dioxane, tetrahydrofuran and diisopropyl ether; and mixtures of two or more of these.

The (B) used in the present invention may optionally contain additives usually added to paints and inks such as a thermosetting catalyst, a photopolymerization initiator, an antifoaming agent, a leveling agent and a coupling agent. can do.

In the present invention, when (B) is an alkyd resin or an unsaturated polyester resin, examples of the thermosetting catalyst include peroxides such as tertiary butyl peroxybenzoate, benzoyl peroxide and methyl ethyl ketone peroxide. And azo compounds such as azobisisobutyronitrile and azobisisovaleronitrile.

In the present invention, when (B) is an epoxy resin, examples of the thermosetting catalyst include imidazoles such as 2-methyl-4-ethylimidazole, phenol, and the like.
Examples include phenols such as cresol and bisphenol A.

In the present invention, examples of the thermosetting catalyst used when (B) is a two-pack urethane resin include dibutyltin dilaurate, tin octylate, triethylamine and the like.

The amount of the thermosetting catalyst optionally used is
It is usually at most 10% by weight, preferably at most 5% by weight, based on the weight of (B).

In the present invention, when (B) is an ultraviolet curable resin, the photopolymerization initiator used includes benzoin alkyl ether, benzyl dimethyl ketal, 1-hydroxycyclohexyl phenyl ketone, 2-hydroxy-2-methyl-1 -Phenylpropan-1-one, benzophenone, methylbenzoylformate, isopropylthioxanthone and the like.

The amount of the photopolymerization initiator is usually at most 20% by weight, preferably at most 6% by weight, based on the weight of (B).

[0038]

EXAMPLES The present invention will be described below with reference to examples, but the present invention is not limited to these examples. Parts in Examples are parts by weight.

Example 1 Bisphenol A type epoxy resin [Epicoat 828, manufactured by Yuka Shell Epoxy Co., Ltd.] 70 parts 1,6-hexamethylene glycol diglycidyl ether [SR-16H, manufactured by Sakamoto Pharmaceutical Co., Ltd.] 14 Part Spherical alumina having an average particle size of 30 μm and Knoop hardness of 2800 [Alumina Beads CB-A30S, manufactured by Showa Denko KK] 15 parts Thixotropic agent [Aerosil 200, manufactured by Nippon Aerosil Co., Ltd.] 0.5 part Sedimentation 0.5 parts of inhibitor [Orbene, manufactured by Shiraishi Industry Co., Ltd.] These were uniformly mixed with a planetary mixer. This is designated as Main Agent 1. The viscosity of a mixture obtained by uniformly mixing 17 parts of m-xylylenediamine and 20 parts of toluene with 100 parts of the main agent 1 was 400 centipoise. This was coated on printed paper so as to have a dry thickness of 25 μm, and cured at 40 ° C. for 20 minutes. When a Taber abrasion test was performed on the coated paper according to JIS K-6902, the amount of abrasion at 200 rotations was 30 mg.

Production Example 1 In a glass reactor equipped with a dropping funnel, a thermometer, a reflux condenser and a stirring rod, 1,000 parts of polytetramethylene glycol having a molecular weight of 1,000 and 444 parts of isophorone diisocyanate were charged. And react for 3 hours.
Thereafter, the mixture was cooled to 80 ° C. or lower, 232 parts of 2-hydroxyethyl acrylate was added, and reacted at 80 ° C. until the isocyanate group disappeared. This is designated as urethane acrylate 1.

Example 2 Urethane acrylate 1 20 parts Trimethylolpropane triacrylate 20 parts Bisphenol A (EO) ₄ diacrylate 20 parts Phenol (EO) ₂ acrylate 20 parts Spherical alumina having an average particle size of 30 μm and a Knoop hardness of 2800 [ Showa Denko KK, alumina beads CB-A30S] 15 parts Photoinitiator [Merck, Darocur 1173] 3 parts Thixotropic agent [Nippon Aerosil Co., Ltd., Aerosil 200] 0.5 parts Toluene 5 parts These Had a viscosity of 440 centipoise. The average molecular weight between crosslinks of the reactive resin is 2
72. This is coated on a printed paper so as to have a dry thickness of 25 μm,
Irradiation at mJ / cm ² was performed. The wear amount in the same Taber abrasion test as in Example 1 was 25 mg.

Example 3 Urethane acrylate 1 20 parts Trimethylolpropane triacrylate 20 parts Bisphenol A (EO) ₄ diacrylate 10 parts Phenol (EO) ₂ acrylate 30 parts Spherical alumina having an average particle size of 20 μm and a Knoop hardness of 2800 [ Alumina Beads CB-A20S, manufactured by Showa Denko KK 15 parts Thixotropy-imparting agent [Aerosil 200, manufactured by Nippon Aerosil Co., Ltd.] 0.5 parts The viscosity of a mixture obtained by uniformly mixing these was 740 centipoise. The average molecular weight between crosslinks of the reactive resin is 2
87. This was coated on a printed paper so as to have a dry thickness of 20 μm, and an electron beam was applied at 3 Mr.
irradiation. The amount of abrasion in the same Taber abrasion test as in Example 1 was 18 mg.

Comparative Example 1 Urethane acrylate 1 20 parts Trimethylolpropane triacrylate 20 parts Bisphenol A (EO) ₄ diacrylate 20 parts Phenol (EO) ₂ acrylate 20 parts Photoinitiator [Merck, Darocur 1173] 3 parts Thixotropic properties Additive [Aerosil 200, manufactured by Nippon Aerosil Co., Ltd.] 0.5 parts Toluene 5 parts The viscosity of a mixture obtained by uniformly mixing these was 400 centipoise. This is coated on a printed paper so as to have a dry thickness of 25 μm,
Irradiation at mJ / cm ² was performed. In the same Taber abrasion test as in Example 1, the coating layer was completely removed and the substrate was scraped off.

Comparative Example 2 Urethane acrylate 1 20 parts Trimethylolpropane triacrylate 20 parts Bisphenol A (EO) ₄ diacrylate 10 parts Phenol (EO) ₂ acrylate 30 parts Thixotropic agent [Aerosil 200 manufactured by Nippon Aerosil Co., Ltd.] 0.5 part The viscosity of those obtained by uniformly mixing these was 720 centipoise. This was coated on a printed paper so as to have a dry thickness of 20 μm, and an electron beam was applied at 3 Mr.
irradiation. In the same Taber abrasion test as in Example 1, the coating layer was completely removed and the substrate was scraped off.

[0045]

According to the coating composition of the present invention, a specific amount of spherical particles having an average particle diameter in a specific range is added to a reactive resin, and the relationship between the average film thickness of the coating layer and the above-mentioned spherical particles is determined. By being specified, a coating film having excellent scratch resistance and flexibility as well as excellent transparency and surface smoothness of the coating film can be obtained. Therefore, the surface of a paper, plastic sheet or film or the like coated with the coating composition of the present invention is hardly scratched by friction or scratching, and even if the base material is bent because the film itself is flexible. The film does not crack and the appearance is good. Because of such effects, the composition of the present invention is extremely useful as a coating agent for protecting a printed surface such as a printed paper, a plastic sheet or a film.

──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Haruo Ohno 1-1-1, Ichigaya-Kagacho, Shinjuku-ku, Tokyo Inside Dai Nippon Printing Co., Ltd. (72) Inventor Makoto Katsukawa 11-1 Hitohashinohoncho, Higashiyama-ku, Kyoto-shi (56) References JP-A-64-69675 (JP, A) JP-A-5-65429 (JP, A) JP-A-61-268731 (JP, A) (58) Field (Int.Cl. ⁶ , DB name) C09D 7/12 C09D 5/00 C09D 175/04-175/16

Claims (12)

(57) [Claims] The present invention comprises spherical inorganic particles (A1) having a Knoop hardness of 1300 kg / mm ² or more and an average particle diameter of 3 to 50 μm and a reactive resin (B), and the content of ( A1 ) is ( A1 ). A
1 ) and 5 to 30% by weight based on the total amount of (B), and the average particle size d (μm) of ( A1 ) satisfies the following formula (1): . 0.3t ≦ d ≦ 2.0t (1) [where t is the average film thickness (μm) of the coating layer. ] 2. A composition of claim 1 wherein the spherical inorganic particles (A1) is spherical alumina particles. 3. A composition according to claim 1 or 2 wherein the content of aluminum oxide in the spherical inorganic particles (A1) is 90 wt% or more. 4. A reactive resin (B) A composition according to any one of claims 1 to 3, a thermosetting resin. 5. A reactive resin (B) The composition according to any one of claims 1 to 3, which is an ionizing radiation curable resin. 6. The polyether-based urethane (meth) acrylate represented by the following general formula (2) at least 10% by weight of the reactive resin (B) . A composition as described. _{^{CH 2 = C (R 1)}} -COOCH 2 CH 2 -OCONH-X-NHCOO - [- CH (R 2) - (CH 2) n -O-] m-CONH-X-NHCOO -CH 2 CH 2 OCOC (R ¹ ) = CH ₂ (2) (wherein, R ¹ and R ² are each hydrogen or a methyl group, X is a diisocyanate residue, n is an integer of 1 to 3, m
Is an integer of 6 to 60. ) 7. The average molecular weight between crosslinks after curing the reactive resin (B) with heat or ionizing radiation is 150 to 1,000.
The composition according to any one of claims 1 to 6, wherein 8. dissolving the reactive resin (B), and one or more solvents having a boiling point of 70 ° C. to 150 DEG ° C. at atmospheric pressure (A
The composition according to any one of claims 1 to 7 , comprising 30% by weight or less based on the total amount of 1 ) and (B). 9. Spherical particles having an average particle size of 3 to 50 μm
(A) and ionizing radiation-curable reactive resin (B1)
And the content of (A) is the total amount of (A) and (B1)
5 to 30% by weight with respect to the average particle diameter d of (A)
(Μm) satisfies the following expression (1).
Composition for coating. 0.3t ≦ d ≦ 2.0t (1) [However, t is the average film thickness (μm) of the coating layer.
You. ] 10. An ionizing radiation-curable reactive resin (B)
At least 10% by weight of 1) is represented by the following general formula (2).
Polyether-based urethane (meth) acrylate
10. The composition of claim 9, wherein the composition is present. _{^{CH 2 = C (R 1)}} -COOCH 2 CH 2 -OCONH-X-NHCOO - [- CH (R 2) - (CH 2) n -O-] m -CONH-X-NHCOO -CH 2 CH 2 OCOC (R ¹ ) = CH ₂ (2) (wherein R ¹ and R ² are each hydrogen or a methyl group)
X is a diisocyanate residue, n is an integer of 1 to 3, m
Is an integer of 6 to 60. ) 11. An ionizing radiation-curable reactive resin (B)
1) Average amount between crosslinks after curing with heat or ionizing radiation
The amount of particles is 150 to 1,000,
Composition. 12. An ionizing radiation-curable reactive resin (B)
1) is dissolved and the boiling point at normal pressure is 70 ° C. to 150 ° C.
One or more solvents are added to the total amount of (A) and (B1).
12 to 30% by weight or less.
Composition.