JPH1034071A - Surface treatment of base body - Google Patents

Abstract

PROBLEM TO BE SOLVED: To give hydrophilicity with excellent durability to a base body by forming a base coating layer of (meta)acrylate having two or more polymerizable unsatd. groups in the molecule on a base body, irradiating the surface with UV rays while the surface is in contact with hydrophilic polymers so as to cause graft polymn. reaction of the hydrophilic polymers. SOLUTION: A base coating layer compsn. containing (meta)acrylate having two or more polymerizable unsatd. groups in the molecule, other structural materials and additives are dissolved in an org. solvent to prepare a soln. The soln. is applied on the surface of a base body by spray coating, etc., to form a base coating layer. The thickness of the base coating layer is preferably 0.1 to 20μm. The surface of the base coating layer as in contact with hydrophilic polymers having a photopolymn. initiating part in the side chains is irradiated with UV rays to cause graft polymn. reaction of the hydrophilic polymers. As for the photopolymn. initiating part in the hydrophilic polymers having photopolymn. initiating part in the side chains, such a part having property to open and produce radicals by irradiation of UV rays is preferably used.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a treatment method for imparting hydrophilic properties to a substrate surface.

[0002]

2. Description of the Related Art Conventionally, attempts have been made to impart various functions to plastic substrates, inorganic material substrates, and the like. For example, in order to hydrophilize the surface of a plastic substrate, a method of introducing a polar group to the substrate surface by performing a flame treatment, a corona treatment, a low-temperature plasma treatment, or the like is known. It was difficult to do. In addition, there is a problem that the hydrophilic property changes with time.

On the other hand, a method of graft-polymerizing a hydrophilic monomer onto a substrate surface (Yoshihito Raft, Functional Materials, 2, No. 7,
1, 1982, CMC Co., Ltd. / Yoshito Raft, Industrial Materials, 31, No. 7, 62, 1983, published by Nikkan Kogyo Shimbun), it is possible to control the functional group to be introduced, and it is said that there is almost no change with time. But,
In the above method, peroxide or the like is generated on the substrate surface by radiation or plasma, and graft polymerization of the monomer is performed by using this as a starting point, and it takes a long time to obtain sufficient hydrophilic performance by thermal polymerization. Is disadvantageous in manufacturing.

[0004]

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and provides a processing method for imparting a hydrophilic property with excellent durability to a substrate by short processing which is advantageous in production.

[0005]

According to the present invention, there is provided a method for treating a surface of a substrate, comprising the step of forming an undercoat layer comprising a (meth) acrylate having two or more polymerizable unsaturated groups in a molecule on the substrate. The method is characterized in that the surface is irradiated with ultraviolet light in a state in which the hydrophilic polymer having a photopolymerization initiation part in a side chain is brought into contact with the surface to cause a graft polymerization reaction of the hydrophilic polymer.

The substrate to be treated in the present invention includes not only organic polymers such as polyolefin resin, polyester resin, acrylic resin, polycarbonate, polyvinyl chloride and polystyrene, but also inorganic materials such as glass, ceramic and metal. Substances: It is also possible to treat various composite materials and the like, such as glass fiber dispersed in unsaturated polyester resin. The base material may be pretreated for the purpose of improving the adhesion. Examples of the pretreatment include corona discharge treatment, plasma treatment, treatment with ionizing active rays such as ultraviolet rays, electron beams, and radiation, surface roughening treatment, chemical treatment, and primer treatment.

The above (meth) acrylates having two or more polymerizable unsaturated groups in the molecule include pentaerythritol tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, dipentaerythritol pentaacrylate, dipentaerythritol hexa Acrylate, caprolactone-modified dipentaerythritol hexaacrylate, trimethylolpropane tri (meth) acrylate, EO-modified trimethylolpropane triacrylate, PO-modified trimethylolpropane triacrylate, ditrimethylolpropane tetraacrylate, bisphenol A di (meth) acrylate, EO Modified bisphenol A di (meth) acrylate, dimethylol tricyclodecane diacrylate, neopentyl glycol di Meth) acrylate, tris (acryloyloxyethyl) isocyanurate, tris (methacryloxyethyl) isocyanurate. Further, a bifunctional or higher functional urethane acrylate oligomer, polyester acrylate oligomer, polyether acrylate oligomer, epoxy acrylate oligomer, or the like may be used. The (meth) acrylate having two or more polymerizable unsaturated groups in the molecule may be used alone or in combination of two or more.

In the undercoat layer of the present invention, an organic material, an inorganic material, another composite material, or the like may be mixed in addition to the (meth) acrylate having two or more polymerizable unsaturated groups in the molecule. Since the durability of the hydrophilic property to be imparted differs depending on the adhesion between the base material and the undercoat layer, it is preferable to select a material used for the undercoat layer that improves the adhesion between the base material and the undercoat layer.

Furthermore, a photopolymerization initiator can be added to the undercoat layer of the present invention for the purpose of accelerating the crosslinking reaction of the (meth) acrylate.

Examples of the photopolymerization initiator include sulfides such as sodium methyl dithiocarbamate sulfide, tetramethylthiuram monosulfide, diphenyl monosulfide, dibenzothiazoyl monosulfide and disulfide activated by ultraviolet light; thioxanthon, ethylthioxanthone Thioxanthone derivatives such as, 2-chlorothioxanthone, diethylthioxanthone and diisopropylthioxanthone; hydrazone,
Diazo compounds such as azobisisobutyronitrile and benzenediazonium; benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzophenone, dimethylaminobenzophenone, Michler's ketone, benzylanthraquinone,
aromatic carbonyl compounds such as t-butylanthraquinone, 2-methylanthraquinone, 2-ethylanthraquinone, 2-aminoanthraquinone, 2-chloroanthraquinone, benzyldimethylketal and methylphenylglyoxylate; 1-hydroxycyclohexylphenyl ketone, Hydroxy-2-methyl-1-phenylpropan-1-one, 4- (2-hydroxyethoxy) phenyl (2-hydroxy-2-propyl) ketone, 2,2-diethoxyacetophenone, 2,2-dimethoxyacetophenone, etc. Acetophenone derivative of 4
-Methyl dimethylaminobenzoate, ethyl 4-dimethylaminobenzoate, butyl 4-dimethylaminobenzoate,
Dialkylaminobenzoic acid esters such as isopropyl 4-diethylaminobenzoate; peroxides such as benzoyl peroxide, di-t-butyl peroxide, dicumyl peroxide, cumene hydroperoxide; 9-phenylacridine, 9-p Acridine derivatives such as -methoxyphenylacridine, 9-acetylaminoacridine, benzacridine; 9,10-dimethylbenzphenazine, 9-methylbenzphenazine,
Phenazine derivatives such as 10-methoxybenzphenazine; quinoxaline derivatives such as 4,4 ', 4 "-trimethoxy-2,3-diphenylquinoxaline; 2,4,5
-Triphenylimidazoyl dimer; halogenated ketone; acylated phosphorus compounds such as acylphosphine oxide and acylphosphonate. Also, 2-nitrofluorene activated by visible light, 2,4,6-
Tris (trichloromethyl) -1,3,5-triazine, 3,3′-carbonylbiscoumarin, thiomichler ketone and the like can also be used.

The amount of the photopolymerization initiator added is 2 per molecule.
(Meth) acrylate 1 having the above polymerizable unsaturated group 1
It is preferably 0.1 to 20 parts by weight based on 00 parts by weight. If the amount is too small, the purpose of accelerating the crosslinking reaction cannot be achieved, and if the amount is too large, the effect is not particularly improved, which is uneconomical.

The undercoat layer of the present invention may optionally contain a filler such as silica fine particles, an ultraviolet absorber, an antioxidant, a leveling agent, a surfactant and the like.

The undercoat layer composition containing (meth) acrylate having two or more polymerizable unsaturated groups in the molecule, other constituent materials, additives and the like is dissolved in an organic solvent to form a solution. , Bar coating, dipping, roll coating, spin coating, or the like, is applied to the substrate surface to provide an undercoat layer of the present invention.

If the undercoat layer is too thin, it is difficult to form a uniform layer. If the undercoat layer is too thick, the economic efficiency deteriorates.

A hydrophilic polymer having a photopolymerization initiation part in a side chain on the surface of an undercoat layer provided on the above-mentioned substrate and comprising a (meth) acrylate having two or more polymerizable unsaturated groups in a molecule. Is irradiated with ultraviolet light in a state where the polymer is in contact with the polymer to cause a graft polymerization reaction of the hydrophilic polymer.

In the above hydrophilic polymer having a photopolymerization initiation part in a side chain, it is preferable to use, as the photopolymerization initiation part, one having a property of being cleaved by ultraviolet rays to generate radicals. Specifically, those having a chemical structure represented by the general formula (II) can be used.

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Hereinafter, a method for preparing a hydrophilic polymer having a photopolymerization initiation part in a side chain will be described with reference to specific examples.

4- (2-Hydroxyethoxy) phenyl- (2-hydroxy-2-propyl) ketone represented by the formula (III) (commercially available from Ciba-Geigy under the trade name "Irgacure 2959"). ) And 2- (meta)
By the reaction of acryloxyethyl isocyanate or a derivative of (meth) acrylic acid or (meth) acrylic acid, it is possible to obtain a compound represented by the formula (IV) having a photopolymerization initiation part and a polymerizable unsaturated group at the terminal. I can do it.

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By copolymerizing the compound (IV) with a monomer having at least one polymerizable unsaturated group and at least one hydrophilic group in the molecule, the hydrophilic polymer having a photopolymerization initiation portion of the present invention in a side chain. And a conductive polymer can be obtained.

The hydrophilic group includes a hydroxyl group, a sulfonic group, a sulfonic group, a primary, secondary, tertiary amino group or amide group, a quaternary ammonium group, a carboxylic group, a carboxylic group, a phosphoric group, Examples include an acid base, a polyethylene glycol chain, a morpholino group, and a sulfate group. Those having an acidic group and a basic group may be used after being subjected to a neutralization reaction before or after the graft polymerization.

Specific examples of the monomer having at least one polymerizable unsaturated group and at least one hydrophilic group in the molecule include 2-hydroxyethyl (meth) acrylate,
2-hydroxypropyl (meth) acrylate, glycerol (meth) acrylate, 2-acrylamide-2
-Methylpropanesulfonic acid, sodium sulfonic acid ethoxy (meth) acrylate, (meth) acrylamide, N, N-dimethylaminoethyl (meth) acrylate, N, N-diethylaminoethyl (meth) acrylate, N-isopropylacrylamide, N-dimethylaminopropylacrylamide, 2-methacryloxyethyltrimethylammonium chloride, (meth) acrylic acid, sodium (meth) acrylate, 2- (meth) acrylate
Acryloyloxyethyl succinic acid, 2- (meth) acryloyloxyethyl phthalic acid, 2- (meth) acryloyloxyethyl hexahydrophthalic acid, ω-carboxy-polycaprolactone monoacrylate, ethylene oxide-modified phosphoric acid (meth) acrylate, polyethylene Glycol (meth) acrylate, acryloyl morpholine, styrene sulfonic acid and the like can be mentioned. These may be used alone or in combination of two or more.

From the viewpoint of the hydrophilicity and durability of the substrate, the most preferable result is obtained when a monomer having a sulfonic acid group or a sulfonic acid group as the hydrophilic group is used. Examples of the monomer having a sulfonic acid group include 2-acrylamido-2-methylpropanesulfonic acid, p-styrenesulfonic acid, vinylsulfonic acid, and allylsulfonic acid, and salts thereof may be used.

When the above compound (IV) is copolymerized with a hydrophilic monomer, the ratio of the compound (IV) in the hydrophilic polymer is preferably 5 to 50 mol%. Compound (I
If the proportion of V) is too large, the hydrophilic property will not be sufficiently exhibited, and if the proportion of the hydrophilic monomer is too large, the progress of the graft polymerization reaction will be insufficient, resulting in poor durability.

Examples of the method for bringing the hydrophilic polymer into contact with the surface of the substrate provided with the undercoat layer include coating methods such as dipping, spraying, potting, and curtain coating.

To facilitate the coating operation, the hydrophilic polymer may be diluted with a solvent before use. The solvent used is preferably water or a mixture of water and a polar solvent.

The graft polymerization reaction is carried out by irradiating ultraviolet rays with the hydrophilic polymer in contact with the surface of the undercoat layer provided on the substrate. For the irradiation of the ultraviolet rays, an ultrahigh-pressure mercury lamp, a high-pressure mercury lamp, a metal halide lamp, a xenon lamp, a low-pressure germicidal lamp, or the like can be used as a light source.

The irradiation amount of the ultraviolet ray depends on the type of the photopolymerization initiation part,
Varies depending on the content, but, 100mJ / cm ² ~20J
/ Cm ² is appropriate.

In order to prevent oxygen inhibition, it is preferable to perform ultraviolet irradiation in an inert gas atmosphere or in a state of being laminated with a transparent plastic film, a glass plate or the like.

Depending on the type of the hydrophilic group in the hydrophilic polymer, it is preferable to perform an optional post-treatment to stabilize the functional group after polymerization. For example, when a monomer having a carboxylic acid group, a sulfonic acid group, or a phosphoric acid group is used, it is preferable to perform an alkali treatment to convert the carboxylic acid group or the like into a salt of an alkali metal or an alkaline earth metal.
For the alkali treatment, for example, an aqueous solution or an alcohol solution of sodium carbonate, sodium hydrogen carbonate, potassium carbonate, sodium hydroxide, potassium hydroxide, magnesium carbonate or the like can be used. The concentration of the alkaline solution is preferably 0.1 to 5% by weight so that the functional surface is not affected. After performing the above treatment on the base material, it is preferable to remove excess deposits by washing with water or the like.

It is known that when a hydrophilic group is imparted to a substrate by corona treatment or the like, the hydrophilic group spontaneously digs into the substrate and disappears from the surface. In addition, since the undercoat layer is configured to crosslink, the hydrophilic monomer can be present on the surface without causing the above-mentioned undercut. The method of the present invention is particularly advantageous as a means for imparting hydrophilicity to a substrate.

[0031]

【Example】

Example 1 <Synthesis of a photopolymerization initiator having a polymerizable unsaturated group (chemical formula (V))>

Embedded image The inside of a glass container equipped with a cooling pipe and a nitrogen introduction pipe is replaced with nitrogen, 30 g of tetrahydrofuran (THF) is added, and 4- (2-hydroxyethoxy) -phenyl (2-
Hydroxy-2-propyl) ketone (Circa Geigy, Irgacure 2959) 10.0 g (4.46 ×
10 ^-2 mol) was dissolved. 2-methacryloxyethyl isocyanate (Karenz MOI, manufactured by Showa Denko KK)
6.92 g (4.46 × 10 ⁻² mol) was added to form a uniform solution, and the mixture was stirred at room temperature while dropwise adding 90 mg of di-n-butyltin dilaurate as a catalyst. The temperature of the reaction solution rose in a few minutes. After continuing stirring at room temperature for 3 hours, the reaction was left at 50 ° C. for 3 hours to complete the reaction.

The THF was removed under reduced pressure to obtain a solid product. The IR spectrum of the product was measured by the KBr tablet method. The absorption derived from the isocyanate group at about 2280 cm ^-1 derived from the raw material 2-methacryloxyethyl isocyanate disappears, and the absorption derived from the NH group in the urethane bond of the product is reduced to about 3400 cm ^-1 (NH
(Stretching) and around 1550 cm ^-1 (NH bending angle). From the above, it was confirmed that the product had a structure represented by the chemical formula (V).

<Synthesis of hydrophilic polymer having photopolymerization initiation part (chemical formula (VI))>

Embedded image The inside of a glass container equipped with a cooling tube and a nitrogen inlet tube was purged with nitrogen, and 40 g of dimethyl sulfoxide (DMSO) was charged. 5.0 g of the compound (V) obtained above (5.28 × 1
0 ^-3 mol), sodium p-styrenesulfonate 9.
78 g (4.75 × 10 ^-2 mol) were dissolved. Azobisisobutyronitrile (AIBN) 120 mg in DM
The operation of adding a solution dissolved in 2 g of SO and performing polymerization for 3 hours was repeated three times, and polymerization was performed for a total of 9 hours. A hydrophilic polymer (VI) was obtained. The solution after the reaction was poured into methyl ethyl ketone (MEK) to precipitate a hydrophilic polymer (VI), which was collected by filtration. As measured by GPC, the weight average molecular weight Mw = 17,000 and the molecular weight distribution Mw / Mn =
3.2.

<Formation of Undercoat Layer> A urethane acrylate oligomer (U-15H, manufactured by Shin-Nakamura Chemical Co., Ltd.) which is a (meth) acrylate having two or more polymerizable unsaturated groups in the molecule.
A) 100 parts by weight of MEK were dissolved in 400 parts by weight of MEK, and applied on an acrylic plate (Acrylite EX, 3 mm thick, manufactured by Mitsubishi Rayon Co., Ltd.) using a Meyer bar. 2 at 80 ° C
After drying for an minute, an undercoat layer having a thickness of 1.7 μm after drying was provided.

<Graft Polymerization> The hydrophilic polymer (V
I) 1.0 g was dissolved in 9.0 g of ion-exchanged water and potted on the undercoat layer. Ultraviolet rays were irradiated for 5 seconds (1 J / cm ² ) using a high-pressure mercury lamp as a light source in a state in which a slide glass having a thickness of 1 mm was laminated thereon. The slide glass was removed, excess adhered substances on the surface were washed off with running water, and then dried to obtain a surface-treated substrate.

Examples 2 and 3 In place of the acrylic plate in Example 1, as a substrate, Example 2 was a polycarbonate plate (made by Asahi Glass Co., Lexan, 3 mm thick), and Example 3 was a polyvinyl chloride plate (3 mm thick). A substrate having been subjected to surface treatment was obtained in the same manner as in Example 1 except that a sun plate (3 mm thick, manufactured by Kyo Kasei Co., Ltd.) was used.

Example 4 <Hydrophilic polymer having photopolymerization initiation part (chemical formula (VI)
Synthesis of I))>

Embedded image The inside of a glass container equipped with a cooling tube and a nitrogen inlet tube is purged with nitrogen, 40 g of dimethyl sulfoxide (DMSO) is charged, and 9.83 g of 2-acrylamido-2-methylpropanesulfonic acid (NBA, TBAS-Q) (4.
75 × 10 ^-2 mol), sodium carbonate monohydrate 2.9
After 5 g (2.38 × 10 ⁻² mol) was added and completely dissolved, 5.0 g of the compound (V) obtained above was further added.
(5.28 × 10 ⁻³ mol) was added and dissolved. Azobisisobutyronitrile (AIBN) 120 mg in DM
The operation of adding a solution dissolved in 2 g of SO and performing polymerization for 3 hours was repeated three times, and polymerization was performed for a total of 9 hours. A hydrophilic polymer (VII) was obtained. The solution after the reaction was poured into methyl ethyl ketone (MEK) to precipitate a hydrophilic polymer (VII), which was collected by filtration. As measured by GPC, weight average molecular weight Mw = 32,000, molecular weight distribution Mw / Mn
= 2.9.

<Formation of Undercoat Layer> An undercoat layer was provided in the same manner as in Example 1.

<Graft Polymerization> A substrate was surface-treated in the same manner as in Example 1, except that the hydrophilic polymer (VII) was used instead of the hydrophilic polymer (VI). .

Example 5 <Formation of undercoat layer (addition of photopolymerization initiator)> Urethane acrylate oligomer (Shin-Nakamura Chemical Co., Ltd.) which is a (meth) acrylate having two or more polymerizable unsaturated groups in the molecule
U-15HA) 1.0 g and 1-hydroxyethoxycyclohexyl phenyl ketone (Irgacure 184, Ciba-Geigy) 0.02 g were added to MEK 4.0.
g, and applied on an acrylic plate (Acrylite EX, 3 mm thick, manufactured by Mitsubishi Rayon Co., Ltd.) using a Mayer bar. Dry at 80 ° C. for 2 minutes, dry thickness 1.6
A μm undercoat layer was provided. <Graft polymerization> A base material subjected to surface treatment in the same manner as in Example 1 was obtained.

Example 6 <Formation of Undercoat Layer> Pentaerythritol hexaacrylate (DPHA, manufactured by Nippon Kayaku Co., Ltd.), which is a (meth) acrylate having two or more polymerizable unsaturated groups in the molecule, is 1.0.
g was dissolved in 4.0 g of MEK, and an acrylic plate (Acrylite EX, manufactured by Mitsubishi Rayon Co., Ltd., 3
mm thickness). It dried at 80 degreeC for 2 minutes, and provided the 1.7-micrometer-thick undercoat layer after drying. <Graft polymerization> A base material subjected to surface treatment in the same manner as in Example 1 was obtained.

Example 7 <Formation of an undercoat layer (addition of a photopolymerization initiator)> A urethane acrylate oligomer which is a (meth) acrylate having two or more polymerizable unsaturated groups in a molecule (manufactured by Shin-Nakamura Chemical Co., Ltd.)
U-15HA) 0.8 g and polymethyl methacrylate (Sumitomo Chemical Co., Ltd., Sumipex BLO-6, average molecular weight 62,000) were dissolved in 4.0 g of MEK, and an acrylic plate (Mitsubishi Rayon) was dissolved using a Meyer bar. Co., Ltd., Acrylite EX, 3 mm thickness). After drying at 80 ° C. for 2 minutes, an undercoat layer having a thickness of 1.8 μm after drying was provided. <Graft polymerization> A base material subjected to surface treatment in the same manner as in Example 1 was obtained.

Example 8 <Formation of Undercoat Layer> An undercoat layer was formed in the same manner as in Example 1. <Graft polymerization> The hydrophilic polymer (VI) obtained in Example 1
1.0 g of polyoxyethylene sorbitan monolaurate (manufactured by Wako Pure Chemical Industries) and 0.1 g of ion-exchanged water 9.
0 g, and applied by potting on the undercoat layer. Ultraviolet rays were irradiated for 5 seconds (1 J / cm ² ) using a high-pressure mercury lamp as a light source in a state in which a slide glass having a thickness of 1 mm was laminated thereon. The slide glass was removed, excess adhered substances on the surface were washed off with running water, and then dried to obtain a surface-treated substrate.

Comparative Example 1 1.0 g of the hydrophilic polymer (VI) obtained in Example 1 was dissolved in 9.0 g of ion-exchanged water, and directly applied by potting onto the acrylic plate. Ultraviolet rays were irradiated for 5 seconds (1 J / cm ² ) using a high-pressure mercury lamp as a light source in a state in which a slide glass having a thickness of 1 mm was laminated thereon. The slide glass was removed, excess adhered substances on the surface were washed off with running water, and then dried to obtain a surface-treated substrate.

Comparative Example 2 Instead of the aqueous hydrophilic polymer (VI) solution, sodium polystyrene sulfonate (PSS, manufactured by Tokuyama Corporation) 0.9
g and 0.1 g of 4- (2-hydroxyethoxy) -phenyl (2-hydroxy-2-propyl) ketone (Irgacure 2959, manufactured by Ciba-Geigy) dissolved in 9.0 g of ion-exchanged water ( Graft polymerization was carried out in the same manner as in Example 1 using the same amount of the photopolymerization initiator as the aqueous solution of the hydrophilic polymer (VI) of Example 1 to obtain a substrate having been subjected to surface treatment.

Comparative Example 3 In place of the aqueous hydrophilic polymer (VI) solution, 0.9 g of sodium p-styrenesulfonate and 4- (2-hydroxyethoxy) -phenyl (2-hydroxy-2-propyl) ketone were used. 0.1 g of Irgacure 2959 (manufactured by Ciba-Geigy) dissolved in 9.0 g of ion-exchanged water (containing the same amount of the photopolymerization initiator as the aqueous hydrophilic polymer (VI) solution of Example 1) Was used to carry out graft polymerization in the same manner as in Example 1 to obtain a surface-treated substrate.

The following evaluations were carried out on the surface-treated substrates of the examples and comparative examples. Table 1 shows the compositions of Examples and Comparative Examples and the results of each evaluation.

<Evaluation of Contact Angle to Water> The surface treatment of the substrate was carried out in a room at a room temperature of 23 ° C. and a humidity of 50% using a contact angle meter (CA-X150, manufactured by Kyowa Interface Science Co., Ltd.). 3 points were measured. Table 2 shows the average values. In addition, after providing the undercoat layer of Example 1 on the base material, the contact angle was similarly measured about the thing irradiated with ultraviolet rays without applying the hydrophilic monomer, and it was 61.2 degrees.

<Evaluation of hot water resistance> The surface-treated substrate was immersed in warm water of 70 ° C. for 24 hours, and then washed with running water. About the substrate surface subjected to the warm water treatment,
The appearance and the contact angle with water were evaluated. In the appearance, a transparent and smooth surface was marked with “○”.

<Evaluation of Adhesion of Substrate> The surface of the substrate subjected to the surface treatment was scratched with a cutter to cut a 1 mm square substrate into one.
00 cellophane adhesive tape (Sekisui Chemical Co., # 2
52, 25mm width, SP adhesive strength 750kg / 25mm
Width) was deposited. One end of the tape was kept at right angles to the surface of the processed product, and the tape was evaluated by the number of bases remaining after being instantaneously peeled off. 10 when all 100 base lines are not peeled
0, and the state where all the layers are peeled is 0.

<Evaluation of Removal of Adhered Substances> On the surface of the surface-treated substrate, a black magic ink No. Draw at 500 and dry at room temperature for 5 minutes. It was wiped off with a Kimwipe under running water, and the removability of the ink was evaluated as follows. ○: easily removed △: can be removed by rubbing strongly
×: Cannot be removed

[0052]

[Table 1]

[0053]

According to the surface treatment method of the present invention, a hydrophilic layer having a photopolymerization initiation part in a side chain is provided on the surface of an undercoat layer comprising a (meth) acrylate having two or more polymerizable unsaturated groups in a molecule. Irradiate with ultraviolet light while contacting the conductive polymer,
By performing the graft polymerization reaction of the hydrophilic polymer, it is possible to impart hydrophilicity with excellent durability to the base material in a short time which is advantageous in production. Furthermore, since the irradiation of ultraviolet rays is used, it is extremely easy to selectively perform treatment for each portion of the base material. The article provided with the hydrophilic surface according to the method of the present invention can easily remove dirt by washing with water, as shown in the evaluation of adhering matter removal. By utilizing this property, an antifouling function can be imparted to the article, which is particularly suitable for an article intended for outdoor use, which is exposed to the wind and rain. In addition, by performing the hydrophilic treatment of the transparent substrate by the method of the present invention, it is possible to obtain an article having excellent transparency and imparted antifogging property.

Claims (3)

[Claims] 1. An undercoating layer comprising a (meth) acrylate having two or more polymerizable unsaturated groups in a molecule, provided on a substrate, and having a hydrophilicity having a photopolymerization initiation part in a side chain. A method for treating a surface of a substrate, comprising irradiating an ultraviolet ray in a state where molecules are in contact with each other to cause a graft polymerization reaction of the hydrophilic polymer. 2. A hydrophilic polymer having a photopolymerization initiation part in a side chain has the following general formula (I) in a polymerization unit: The surface treatment method for a substrate according to claim 1, wherein the substrate has a structure represented by the following formula. 3. The undercoat layer is formed by adding 0.1 to 20 parts by weight of a photopolymerization initiator to 100 parts by weight of a (meth) acrylate having two or more polymerizable unsaturated groups in a molecule. 3. The surface treatment method for a substrate according to 1 or 2.