JPH0657203A - Water-based coating composition - Google Patents

Abstract

PURPOSE:To provide a water-based coating compsn. free of hazards such as toxicity and flammability, and capable of forming a durable coating film good in water repellency, lubricity, releasability and adhesion. CONSTITUTION:A graft copolymer of a radical-polymerizable silicone macromonomer A with a vinyl monomer B contg. a phosphoric acid group and other vinyl monomer C copolymerizable with the macromonomer A and the vinyl monomer B is reacted with an alkali to prepare a graft copolymer capable of being diluted with water, to which a melamine resin capable of being diluted with water is added as the crosslinking agent.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention is mainly used for coating on the surface of a plastic film such as polyvinyl chloride or polyester to impart water repellency, lubricity, releasability and the like to the surface of the film. It relates to an aqueous coating composition.

[0002]

2. Description of the Related Art For example, it is used as a base material for magnetic tapes, thermal transfer ribbons, etc. for the purpose of imparting water resistance, dust resistance, barrier property, peelability, etc. to soft polyvinyl chloride for agriculture, dust-proof polyvinyl chloride, etc. In order to impart water repellency, lubricity, releasability and the like to the front surface or the back surface of a plastic film base material such as polyester type polyethylene terephthalate (PET) or polyethylene naphthalate (PEN), the coating treatment is performed.

Conventionally, as a coating agent used for the surface coating treatment of such a plastic film, a silicone-based or fluorine-based polymer surfactant is added to the base of a synthetic resin emulsion or a water-soluble synthetic resin aqueous solution. Things are offered.

[0004]

However, the above-mentioned conventional coating agent is an addition type in which the polymer surfactant is added to the base to impart water repellency, lubricity, releasability and the like. There is a problem in migration of the above-mentioned polymer surfactant, persistence of effect, etc. Further, the above-mentioned polymer surfactant is present between the plastic film and the coating film, and the adhesion between the above-mentioned plastic film and the coating film. There was also a problem that it had a negative effect on sex.

[0005]

Means for Solving the Problems As a means for solving the above conventional problems, the present invention comprises a radical polymerizable silicone macromonomer A, a vinyl monomer B containing a phosphoric acid group in the molecule, and An aqueous graft copolymer comprising a silicon macromonomer A and another vinyl monomer C copolymerizable with the vinyl monomer B, which is dilutable with water by alkali neutralization, and a water-dilutable melamine resin And an aqueous coating composition comprising

The present invention is described in detail below. [Radical Polymerizable Silicon Macromonomer A] The radical polymerizable silicon macromonomer A used in the present invention is a silicon macromonomer having a radically polymerizable vinyl group at the terminal, and such a silicon macromonomer is, for example, polydialkyl. The α-β unsaturated fatty acid such as acrylic acid, methacrylic acid, itaconic acid, and crotonic acid is introduced by esterification using the OH group at the terminal of siloxane, or methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl by transesterification. Acrylic ester such as methacrylate, monoacrylic or methacrylic ester of polydialkylsiloxane obtained by introducing methacrylic ester,
Alternatively, there is a monoallyl ether of polydialkylsiloxane obtained by introducing a vinyl monomer having an OH group such as allyl alcohol by etherification. Usually, the polydialkylsiloxane has a molecular weight of about 1,000 to 50,000, and an alkyl group having a lower alkyl group having 4 or less carbon atoms is used.

[Phosphoric Acid Group-Containing Vinyl Monomer B] The phosphoric acid group-containing vinyl monomer B used in the present invention is, for example, β-hydroxyethyl acrylate, β-hydroxyethyl methacrylate, β-hydroxypropyl acrylate. , Β-hydroxypropyl methacrylate, polyethylene glycol monoacrylate, polyethylene glycol monomethacrylate, polypropylene glycol monoacrylate, polypropylene glycol monomethacrylate, β-hydroxy-γ chloropropyl acrylate, β-hydroxy-γ chloropropyl methacrylate, etc. It is a mono- or diester of a hydroxyalkyl ester of an acid and phosphoric acid. A more specific example of the phosphoric acid group-containing vinyl monomer B is as follows.

[Chemical 1]

[Chemical 2]

[Chemical 3]

[Chemical 4]

[Other Vinyl Monomer C] The other vinyl monomer C used in the present invention is a monomer copolymerizable with the above silicon macromonomer A and the above phosphoric acid group-containing vinyl monomer B. There are, for example, methyl acrylate, ethyl acrylate, n-butyl acrylate, iso-butyl acrylate, 2-ethylhexyl acrylate, cyclohexyl acrylate, tetrahydrofurfuryl acrylate,
Methyl methacrylate, ethyl methacrylate, n-butyl methacrylate, iso-butyl methacrylate, 2-ethylhexyl methacrylate, stearyl methacrylate, lauryl methacrylate, methyl vinyl ether,
Ethyl vinyl ether, n-propyl vinyl ether, n-
Butyl vinyl ether, iso-butyl vinyl ether, styrene, α-methylstyrene, acrylonitrile, methacrylonitrile, vinyl acetate, vinyl chloride, vinylidene chloride, vinyl fluoride, vinylidene fluoride, 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate,
2-hydroxypropyl acrylate, 2-hydroxypropyl methacrylate, allyl alcohol, glycidyl acrylate, glycidyl methacrylate, glycidyl allyl ether, acrylic acid, methacrylic acid, itaconic acid, crotonic acid, maleic acid, maleic anhydride, citraconic acid, acrylamide, methacryl There are vinyl monomers such as amide, N-methylol acrylamide, N-methylol methacrylamide, dimethylaminoethyl acrylate and dimethylaminoethyl methacrylate.

[Production of Graft Copolymer] The graft copolymer of the present invention is usually produced by solution polymerization. The solvent used for the solution polymerization is usually methanol, ethanol, iso-propanol, sec-propanol, acetone, methyl ethyl ketone, one or more water-soluble organic solvents such as tetrahydrofuran, or one of the water-soluble organic solvent or There is a mixed solvent of two or more kinds and a small amount of water, and as the polymerization initiator used for the solution polymerization, benzoyl peroxide, lauroyl peroxide, cumene hydroperoxide, azobisisobutyronitrile, There are oil-soluble initiators such as azobis valeronitrile.

The monomer formulation is usually about 10 to 50% by weight of one or more kinds of silicon macromonomer A, and 2 to 8% by weight of one or more kinds of phosphoric acid group-containing vinyl monomer B. About 40 to 80% by weight of one or more vinyl monomers C, and the monomer concentration is usually 3
It is about 0 to 50% by weight.

The graft copolymer thus obtained is neutralized with an alkali to be water-soluble or water-dispersible and can be diluted with water. The alkali used at this time is mainly triethylamine,
Amines such as diisopropylamine, diethanolamine, triethanolamine, dimethylethanolamine,
Although there is a volatile alkali such as ammonia, a non-volatile alkali such as caustic soda, caustic potash, and sodium carbonate may be used. The neutralization with the alkali may be complete neutralization or partial neutralization, and the neutralization may be performed before the polymerization.

In the present invention, the water-soluble organic solvent used may be removed by distillation and replaced with water after polymerization or after neutralization with an alkali, if desired.

Further, in the present invention, emulsion polymerization may be applied instead of solution polymerization. In the emulsion polymerization, a nonionic surfactant and / or
Or an anionic surfactant is used, as the polymerization initiator ammonium persulfate, sodium persulfate, potassium persulfate,
A water-soluble initiator such as sodium perborate or a redox system in which the above water-soluble initiator is used in combination with a reducing agent such as sodium hyposulfite, sodium bisulfite and sodium ascorbate is used.

[Preparation] A water-dilutable melamine resin is added as a cross-linking agent to the aqueous graft copolymer solution thus obtained. Examples of the water-dilutable melamine resin include trimethylolmelamine, hexamethylolmelamine, trimethoxymethylolmelamine, hexamethoxymethylolmelamine, methylated melamine, methylolmelamine such as methylethyl-mixed alkylated melamine, lower alkoxymethylolmelamine, lower There are alkylated melamine and the like. The water-dilutable melamine resin is preferably added to the aqueous graft copolymer solution in a solid content ratio of 5 to 30% by weight. When the amount of the melamine resin added is less than 5% by weight, the crosslink density is insufficient and good solvent resistance and physical properties cannot be obtained.
If it exceeds 5% by weight, poor water resistance results.

[Coating] The coating composition of the present invention thus obtained is usually applied to a substrate such as a PVC film or a PET film by a usual coating method such as spraying, roll coating, flow coating or spin coating. It is applied with a film thickness of 1 μm or less. The coating film obtained by the above-mentioned coating is cross-linked even when dried at room temperature, but is usually subjected to forced drying at 100 to 120 ° C for about 3 to 7 minutes.

[0016]

The coating composition of the present invention is water-dilutable and solves the problems of toxicity and flammability of organic solvents. When the substrate is coated with the coating composition of the present invention, crosslinking occurs due to the melamine resin and the phosphoric acid group, resulting in a coating film having good water resistance and physical properties. In the coating film, the water-based graft copolymer has a polysiloxane or polydialkylsiloxane chain in the side chain, so that the polysiloxane or polydialkylsiloxane chain is oriented outside, thereby providing good water repellency, lubricity, and mold release. Since the polysiloxane or polydialkylsiloxane chain is chemically bonded, there is no transfer or migration, and the effect is long-lasting. Also, on the substrate side, a phosphoric acid group-containing vinyl monomer B and vinyl monomer C
Since the main chain derived from is arranged, good adhesion to the substrate can be obtained, and good conductivity can be obtained due to the alkali salt of the phosphate group.

[0017]

【Example】

[Example 1] (Production of Graft Copolymer A) 200 parts by weight of isopropyl alcohol (hereinafter simply referred to as "part") was charged into a 1-liter flask equipped with a stirrer, a thermometer, a condenser, and a nitrogen gas inlet tube, and the mixture was charged with nitrogen gas. Thirty
After bubbling for a minute, the temperature is raised to 80 ° C.
Methyl methacrylate 40 is added to a separately prepared dropping funnel.
Part, β-hydroxyethyl methacrylate 25 parts, Phosmer M (manufactured by Unichemical Co., Ltd., trade name: Acid Phosphooxyethyl Methacrylate) 5 parts, AK-30 (manufactured by Toagosei Chemical Industry Co., Ltd., trade name: Silicon Macromonomer, molecular weight about 30,000) ) 30 parts and 0.5 parts of azobisisobutyronitrile are added, and the mixture is added dropwise over 2 hours. After 1 hour, a solution prepared by dissolving 0.1 part of azobisisobutyronitrile in 30 parts of methyl ethyl ketone was added, and 8
The reaction was carried out at 0 ° C for 5 hours. In this way, the solid content is 3
A 0.3% by weight milky-white resin liquid was obtained. Next, 4.2 parts of dimethylethanolamine and 23 parts of ion-exchanged water were added to the resin liquid.
3 parts was added and the organic solvent was removed azeotropically over 2 hours. Thus, a milky white aqueous graft copolymer A having a solid content of 30% by weight was obtained.

Example 2 (Production of Graft Copolymer B) Using the same apparatus as in Example 1, 30 parts of styrene, 30 parts of β-hydroxyethyl methacrylate, 10 parts of fosmer M, F
M0725 (trade name of Chisso Corporation: methacryloxy group-terminated polydimethylsiloxane, molecular weight 10,000) 3
Polymerization was carried out in the same manner as in Example 1 except that 0 part and a mixed solution of 0.5 part of azobisisobutyronitrile were added dropwise to make 9.6 parts of triethylamine. In this way, a milky white aqueous graft copolymer B having a solid content of 30% by weight was obtained.

[Comparative Example 1] (Production of Comparative Copolymer C) Except that fosmer M was changed to 10 parts of methacrylic acid in Example 2, all were polymerized according to the same composition and operation to obtain a milky white solid having a solid content of 30% by weight. Comparative copolymer C was obtained.

Comparative Example 2 (Production of Comparative Copolymer D) Using the same apparatus as in Examples 1 and 2, ion-exchanged water 2 was added to the flask.
00 parts, sodium dodecylbenzene sulfonate 0.
1 part by weight is charged and the temperature is raised to 80 ° C. while substituting with nitrogen. Separately, 100 parts of methyl methacrylate, 98 parts of butyl acrylate, 2 parts of Phosmer M, 100 parts of deionized water.
Part, 2 parts of sodium dodecylbenzene sulfonate, and 0.5 parts of potassium persulfate were emulsified with a homogenizer, and a monomer emulsion was added dropwise over 2 hours, and then the mixture was kept at 85 ° C. for 3 hours to obtain a milky white emulsion having a solid content of 40% by weight. A comparative copolymer D was obtained.

Samples of the copolymers A, B, C and D obtained in Examples 1 and 2 and Comparative Examples 1 and 2 were prepared according to the formulation shown in Table 1 and rolled on a PET film having a thickness of 100 μm. The film thickness of each sample was 1μ by a coater.
After being coated so as to have a thickness of m and forcedly dried at 110 ° C. for 5 minutes, a test for water resistance and physical properties was performed. The results are shown in Table 1.

[0022]

[Table 1] Crosslinking agent a: Cymel 300 (trade name, manufactured by Mitsui Cyanamid Co., Ltd.) Hexamethoxymethylol melamine Crosslinking agent b: Cymel 303 (trade name, manufactured by Mitsui Cyanamid Co., Ltd.) Methylated melamine resin Additive a: Water-soluble polyether modified silicone Test method Gel fraction: The coating film formed on the Teflon plate was peeled off, and the mixture was ultrasonicated in acetone for 30 minutes to calculate the proportion (% by weight) of the insoluble portion. Adhesion: Cross-cut cellophane tape peeling test Water resistance: 40 ° C-72 hours Dynamic friction coefficient: HEIDON type friction measuring instrument

According to Table 1, in Samples 1, 2 and 3 using the aqueous coating composition of the present invention, good crosslinkability (gel fraction), lubricity (dynamic friction coefficient), adhesion and water resistance were obtained. However, in Comparative Sample 1 in which the comparative copolymer C in which the phosphoric acid group is replaced with a carboxyl group is used, the crosslinkability is poor, and therefore the water resistance is deteriorated, and the lubricity after the water resistance test is significantly reduced. . Similarly, Comparative Sample 2 containing no crosslinking agent was also inferior in crosslinkability, and the water resistance and the lubricity after the water resistance test were significantly reduced. Further, in Comparative Sample 3 in which silicon was not added and silicon was post-added, the crosslinkability was better than Comparative Samples 1 and 2, but lower than Samples 1, 2 and 3, and the lubricity was good. And inferior adhesion.

[0024]

Therefore, in the present invention, an aqueous coating composition having no risk of toxicity and flammability is used to obtain water repellency,
A coating film having good lubricity, releasability and adhesiveness and having durability can be obtained.

 ─────────────────────────────────────────────────── ─── Continued Front Page (72) Inventor Susumu Kawakami 8-3 Ninomachi, Mizuho-ku, Nagoya, Aichi Natco Paint Co., Ltd. (72) Hironori Hata, 8 Ninomachi, Mizuho-ku, Nagoya, Aichi No. 3 Natco Paint Co., Ltd. (72) Inventor Keiji Taniguchi 1-3-6 Nakamagome, Ota-ku, Tokyo Within Ricoh Co., Ltd. (72) Inventor Shigeyuki Harada 1-3-3 Nakamagome, Ota-ku, Tokyo No. 6 Ricoh Co., Ltd.

Claims (1)

[Claims] 1. Radical polymerizable silicone macromonomer A
A vinyl monomer B containing a phosphoric acid group in the molecule, the silicon macromonomer A and the vinyl monomer B
And another vinyl monomer C copolymerizable with the above, and an aqueous graft copolymer dilutable with water by alkali neutralization, and a water-dilutable melamine resin. object