JP2001329124A - Water-based composition and antistatic film using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a water-based composition for forming an antistatic film excellent in both of warm water resistance and water repellency. SOLUTION: This water-based composition comprises (A) a cation-modified copolymer having 1,000 to 80,000 weight - average molecular weight and containing 70-99 mol% ethylene structural unit, 0-15 mol% acrylate structural unit represented by formula (2) and 1-30 mol% acrylamide structural unit represented by formula (3) and (B) a polymer containing fluorine atom in a weight fraction of >25%, and the weight ratio of the component A to total amount of these components A and B is 0.05-0.50.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to an aqueous composition and a water-repellent antistatic film using the same.

[0002]

2. Description of the Related Art Plastics are excellent in lightness, moldability, and appearance.
Widely used for housing of office equipment, automobile parts, various packaging materials, miscellaneous goods, etc. However, plastics have high electrical resistance, so the static electricity generated by friction and peeling accumulates without leaking, which reduces the product value due to dust adhesion and malfunctions due to electric discharge in electronic devices. Problem.

[0003] The use of an antistatic agent is known as a countermeasure against such electrostatic damage.
That is, an antistatic agent composed of an anionic surfactant, a cationic surfactant, an amphoteric surfactant, a nonionic surfactant, or the like can be kneaded into a plastic (internal addition) or applied to the plastic surface (external application). Generally done.

[0004] In the case of internal addition, although the durability of the antistatic effect is relatively good, it is necessary to add it to the entire plastic material, so that a large amount of addition is required, which tends to increase the cost. .

[0005] In the case of external coating, the cost is small because it is applied only to the surface requiring an antistatic effect, but the disadvantage is that the antistatic agent easily falls off due to surface friction or washing, and the effect is easily lost. have.

[0006] On the other hand, clothes and exterior / electric parts such as automobiles used outdoors require a water-repellent treatment to avoid water penetration.

[0007]

SUMMARY OF THE INVENTION
JP-A-4-198309 discloses that an aqueous composition of a polyacrylamide copolymer containing a quaternary ammonium salt is applied to the surface of a plastic to form an antistatic coating film having friction durability. A method has been proposed. However, even with this method, there is still a need for improvement in situations where further durability is required, for example, friction durability under wet conditions and durability against water washing at high temperatures. Further, there is room for improvement in terms of adhesion to a substrate such as a polyethylene terephthalate film.

On the other hand, as another means for obtaining an antistatic coating film, for example, as disclosed in JP-A-2-120370 and JP-A-3-126679, there are known methods such as perchloric acid and thiocyanate. There is known a method in which a conductive salt is contained in a free-radical polymerizable monomer and irradiated with radiation to obtain a cured antistatic cured coating film. However, in this method, the material used for conductivity is low in molecular weight and essentially water-soluble, so that it is at an unsatisfactory level in terms of water resistance.

Similarly, a method of using a quaternary ammonium salt type surfactant, for example, triethylalkyl ether ammonium sulfate as a conductive agent is disclosed in Japanese Patent Application Laid-Open No. 60-1985.
Although it is proposed in JP-A-221414, it has the same drawbacks as described above in that it is a water-soluble low molecular weight compound.

On the other hand, in order to impart water repellency to the fiber, a method of coating with a fluororesin emulsion is used. However, waterproofing and water repellent treatment represented by clothing and the like is characterized by strong hydrophobicity. Yes, water repellency is good, but tends to accumulate static electricity.

Therefore, the antistatic property obtained by imparting hydrophilicity and the water repellency obtained by imparting hydrophobicity are contradictory properties and are incompatible.

The present invention has been made in view of such conventional problems, and an object of the present invention is to provide an antistatic coating having excellent durability such as durability against water washing and water repellency. It is to provide an aqueous composition for forming a film.

[0013]

Means for Solving the Problems The aqueous composition of the present invention comprises:
An aqueous composition containing the following components A and B, wherein the weight ratio of the component A to the total amount of the components A and B is 0.05 to 0.50.

The component A comprises 70 to 99 mol% of an ethylene structural unit represented by the following formula (1), 0 to 15 mol% of an acrylate structural unit represented by the following general formula (2), and Acrylamide structural unit 1 to 30 represented by 3)
Mol%, and a weight average molecular weight of 1,000 to 80,
000, which is a cation-modified copolymer.

[0015]

Embedded image

In the above formula, R1 is a hydrogen atom or a compound having 1 to 1 carbon atoms.
R2 represents an alkylene group having 2 to 8 carbon atoms; R3, R4, and R5 each independently represent an alkyl group having 1 to 12 carbon atoms, an arylalkyl group having 7 to 12 carbon atoms, or a carbon atom having 7 to 12 carbon atoms; An alicyclic alkyl group of 6 to 12;
Represents a halogen atom, CH3OSO3, C2H5OSO3 or R6SO3, wherein R6 represents an alkyl group having 1 to 12 carbon atoms, an arylalkyl group having 7 to 12 carbon atoms, or an alicyclic alkyl group having 6 to 12 carbon atoms.

The component B contains 25% by weight of fluorine atoms.
A polymer or copolymer containing the above.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The matters relating to the implementation of the present invention will be described below in detail. (1) Component A As described above, the cation-modified copolymer used as the component A includes an ethylene structural unit represented by the formula (1), an acrylate structural unit represented by the general formula (2), It is an acrylamide-based copolymer linearly and irregularly arranged containing the acrylamide structural unit represented by the formula (3).

The ethylene structural unit represented by the formula (1) is
70-99 mol% is contained in the molecule. When the content is less than 70 mol%, the durability of the coating film at the time of washing is deteriorated, and when it exceeds 99 mol%, the antistatic effect is poor.
The preferred range is 80-97 mol%.

The acrylate structural unit represented by the general formula (2) is contained in the molecule in an amount of 0 to 15 mol%. If the content exceeds 15 mol%, the coating film becomes sticky. The acrylate structural unit is not essential in the present invention, but is preferable because the presence of the acrylate structural unit improves the miscibility with the component B and the adhesiveness, and makes it easy to obtain a transparent cured coating film. The preferred range of the content ratio of the acrylate structural unit is 1 to 10 mol%.

In this acrylate structural unit, R1
Is a hydrogen atom or an alkyl group having 1 to 4 carbon atoms. When the number of carbon atoms exceeds 4, the coating film becomes too soft and causes stickiness. Specific examples of R1 include a hydrogen atom, a methyl group, an ethyl group, an n-propyl group, an i-propyl group, and an n-
Examples thereof include a butyl group, a sec-butyl group and a t-butyl group, and these groups may be present in one molecule. Of these, a methyl group and an ethyl group are particularly preferred.

The acrylamide structural unit represented by the general formula (3) is contained in the molecule in an amount of 1 to 30 mol%. When the content is less than 1 mol%, the antistatic property is insufficient, and when it exceeds 30 mol%, the high temperature water resistance of the coating film is deteriorated. A preferred range is 2 to 10 mol%.

In this acrylamide structural unit, R
2 is an alkylene group having 2 to 8 carbon atoms. Specific examples include an ethylene group, a propylene group, a hexamethylene group, a neopentylene group, and the like, and these groups may be present in one molecule. Among these, an ethylene group and a propylene group are particularly preferable from the viewpoint of ease of production and economy.

R3, R4 and R5 are each independently an alkyl group having 1 to 12 carbon atoms, an arylalkyl group having 7 to 12 carbon atoms, or an alicyclic alkyl group having 6 to 12 carbon atoms. Specific examples include a methyl group, an ethyl group, n
-Propyl group, i-propyl group, n-butyl group, sec
Alkyl groups such as -butyl group, n-octyl group and n-lauryl group; arylalkyl groups such as benzyl group and 4-methylbenzyl group; alicyclic alkyl groups such as cyclohexyl group and methylcyclohexyl group; The groups may be mixed in one molecule. In these, methyl group,
Ethyl groups are particularly preferred.

X, which is a counter ion of a quaternary ammonium salt, is a halogen atom such as Cl, Br, I, etc .;
Alkyl sulfates such as SO3, C2H5OSO3,
Alternatively, R6SO3, which may be present in one molecule. Here, specific examples of R6SO3 include methanesulfonic acid, ethanesulfonic acid, propanesulfonic acid, dodecanesulfonic acid, paratoluenesulfonic acid, and metaxylenesulfonic acid. X represents Cl, CH3OSO3, C2H5OS from the viewpoint of antistatic performance.
O3, methanesulfonic acid, ethanesulfonic acid, and paratoluenesulfonic acid are preferred.

The cation-modified copolymer of the component A comprising the above structural unit may contain a small amount of other structural units such as acrylic acid, methacrylic acid, acrylonitrile, glycidyl methacrylate, and styrene as long as the effects of the present invention are not impaired. And the like.

The cation-modified copolymer has a weight average molecular weight of 1,000 to 80,000. When the weight average molecular weight is less than 1,000, the physical properties of the coating film are remarkably reduced, and when it exceeds 80,000, the dispersibility in water is reduced. Particularly preferred weight average molecular weight is 3,000-
50,000. Here, the weight-average molecular weight means a monodisperse polystyrene-equivalent weight-average molecular weight measured by gel permeation chromatography (GPC).
No. 139-141, 1987).

The method for producing this cation-modified copolymer is as follows:
There is no particular limitation. For example, JP-A-4-19
As described in JP-A-8309, an ethylene-acrylate copolymer obtained by copolymerizing ethylene and an acrylate by a high-pressure polymerization method is produced, for example, by the method described in JP-A-60-79008. The resulting ethylene-acrylic acid ester-acrylic acid copolymer is amidated with N, N-dialkylaminoalkylamine, and then cationically modified with a quaternizing agent. By doing so, a copolymer of the component A is obtained.

The method for dispersing, emulsifying or solubilizing the copolymer of the component A in water is not particularly limited. For example, as described in JP-A-4-198309, the copolymer, water and, if necessary, a surfactant are charged into a high-pressure vessel equipped with a stirrer such as an autoclave and heated while stirring. By the high-pressure emulsification method described above, a uniform aqueous dispersion can be obtained.

The surfactant is preferably a nonionic or cationic surfactant. The amount of the surfactant is usually 25 parts by weight or less, preferably 25 parts by weight or less, based on 100 parts by weight of the cation-modified copolymer. 20 parts by weight or less. In addition, since the present cation-modified copolymer itself has emulsifying power, a surfactant is not necessarily required.

The heating temperature in the high-pressure vessel is usually 5 to 2 times higher than the temperature at which the cation-modified copolymer melts.
A temperature 0 ° C. higher, that is, 60 to 200 ° C. is preferred. The heating time varies depending on the heating temperature, but about 10 minutes to 1 hour is sufficient.

(2) Component B The polymer used as the component B of the present invention is a polymer or copolymer containing 25% or more by weight of fluorine atoms. The weight fraction of fluorine atoms is preferably 30% to 80%, and if it is less than 25%, good water repellency is not exhibited. The polymer (copolymer) containing 25% or more of fluorine atoms used in the present invention is not particularly limited,
Examples include one or more polymers or copolymers of tetrafluoroethylene, perfluorovinyl ether, hexafluoropropylene, chlorotrifluoroethylene, vinylidene fluoride, fluoroalkyl acrylate, fluoroalkyl methacrylate, and fluoroalkyl siloxane. Further, in order to enhance dispersibility in water, it may be copolymerized with a copolymerizable monomer. In order to further improve the stability, an organic solvent may be used. However, the copolymerizable monomer and the organic solvent are not necessarily essential components. The method of dispersing or emulsifying the present polymer in water is not particularly limited, but the method of dispersing the polymer (copolymer) fine powder in water using a surfactant, or the method of dispersing or emulsifying the fluorine in the water, It can be obtained by emulsion polymerization of an atom-containing monomer or a monomer copolymerizable with the fluorine atom-containing monomer. The copolymerizable monomer is not particularly limited, but may be acrylic acid ester, methacrylic acid ester, aliphatic carboxylic acid vinyl ester, aromatic carboxylic acid vinyl ester, acrylic acid (salt), methacrylic acid (salt). ), Etc., and can be used alone or in combination. As a solvent used for improving stability,
Solvents having solubility in water, such as acetone, methyl ethyl ketone, alcohols having 1 to 4 carbon atoms, dimethyl sulfoxide and dimethylformamide, are preferred. This solvent is 0
Used in the range of ~ 25%.

The surfactant used for dispersion in water is not particularly limited, but nonionic and / or cationic surfactants are preferred.

(3) Aqueous Composition In the aqueous composition of the present invention, the cation-modified copolymer of the component A and the fluorine atom-containing polymer of the component B are uniformly dispersed in water or an aqueous medium containing water as a main component. It was done. The term “dispersion” as used herein is a concept that encompasses macroscopically uniform systems such as those in which these components are dispersed in water, emulsified, and solubilized.

The aqueous composition may be prepared by mixing the above-mentioned A component and the B component with each other in an aqueous dispersion, dispersing the B component in the aqueous dispersion of the A component, and dispersing the aqueous dispersion of the B component. May be dispersed. Of these,
The simplest method is to prepare and mix the aqueous dispersions of the component A and the component B, respectively.

The concentration (solid content) of both components contained in the aqueous composition is 2 to 40% by weight for the component A and 5 to 5% for the component B.
Preferably it is 40% by weight. If the concentration exceeds the above range, application becomes difficult due to separation and increase in viscosity. On the other hand, when the concentration is lower than the above-mentioned concentration, the concentration of the active ingredient becomes small, and the coating film is apt to be uneven.

The weight ratio of the component A to the total of the components A and B is 0.05 to 0.50. If the weight ratio of the component A is less than 0.05, the surface resistance increases, and a good antistatic effect cannot be obtained. When the weight ratio of the component A is more than 0.50, the water repellency of the coating film is remarkably reduced.

The aqueous composition of the present invention may contain a crosslinking agent as a third component. Examples of the crosslinking agent include polyepoxy compounds, melamine compounds, organotin compounds such as dibutyltin dilaurate, and water-soluble or water-dispersible polyisocyanate compounds. In the aqueous composition of the present invention, a cross-linking agent is not always necessary. However, when a cross-linking agent is blended, the strength of the coating film increases and the water resistance also increases.

In the aqueous composition of the present invention, a general extender pigment or the like may be blended for coloring, an antioxidant may be blended for the purpose of imparting heat resistance, and various kinds of additives may be used for adjusting the adhesiveness. Dispersants, anti-skinning agents, leveling agents, defoamers,
Various additives such as a thickener, a film-forming aid, and a release agent can be blended within a range where the performance is not reduced.

The aqueous composition of the present invention can be used as an antistatic agent applied to the surface of various substrates such as plastics. The type of the base material, the coating method, and the coating amount are not particularly limited. Examples of the application method include a spraying process, a brushing process, a roll coater process, and a dipping process. After application, by drying under appropriate conditions, warm water resistance, an antistatic coating film excellent in water repellency is formed,
The antistatic property and the water repellency of the substrate surface can be improved.

[0041]

EXAMPLES Examples of the present invention will be described below, but the present invention is not limited to these examples. Synthesis Example 1 (Synthesis of A1 to A4) As the cation-modified copolymer of the component A, copolymers A1 to A4 having four kinds of constitutions shown in Table 1 were disclosed in JP-A-4-19830.
The aqueous dispersion of each of the copolymers A1 to A4 was prepared by a high-pressure emulsification method according to the method described in JP-A No. 9-No.

[0042]

[Table 1]

Synthesis Example 2 (Synthesis of B1 to B4) In a 1000 ml flask equipped with a stirrer, a heating device, a dropping funnel, a thermometer, a reflux cooling device, and a nitrogen inlet tube, Table 2 was prepared.
After mixing and stirring and dispersing a mixture of a monomer and an organic solvent having the composition described in (3), sodium alkylbenzene sulfonate (3 g) and distilled water (370 g), ammonium persulfate
30 g of a 3% aqueous solution was added and reacted at 70 ° C. for 3 hours to obtain aqueous dispersions B-1 to B-4 of a (co) polymer containing a fluorine atom.

[0044]

[Table 2]

Table 3 shows the optional crosslinking agent (component C).

[0046]

[Table 3]

Examples 1 to 7 and Comparative Examples 1 to 5 The aqueous dispersions A1 to A4 obtained in Synthesis Example 1, B1 to B4 shown in Table 2, and C1 and C2 shown in Table 3 were used. Was mixed and / or diluted so as to have the component concentrations shown in Table 4, to prepare the aqueous compositions of Examples 1 to 7 and the aqueous compositions of Comparative Examples 1 to 5.

[0048]

[Table 4]

Each of the obtained aqueous compositions was applied to the surface of a glass plate at 100 g / m 2. The applied substrate is about 120 ° C
After 10 minutes for forming a film, the following items were tested. Further, in the water washing test, after immersion in distilled water at room temperature (23 ° C.) for 10 minutes and drying at room temperature, the same items were tested.

Surface Specific Resistance The sample was left in an environment of 20 ° C. and 65% RH for 24 hours, and the surface specific resistance was measured using an ultra high resistance meter R8340 (manufactured by Advantest).

Contact Angle The contact angle was measured according to JIS-6768 wetting test method. Table 5 shows the test results of Examples 1 to 7 and Comparative Examples 1 to 5.
Shown in

[0052]

[Table 5]

Examples 1 to 7 show good surface resistance and water repellency, and there is no decrease in the surface specific resistance and water repellency in the warm water resistance test (washing test). On the other hand, Comparative Example 1 in which only the component A was formed, Comparative Examples 2 and 3 in which only the component B was formed, and Comparative Example 4 in which the weight ratio of the component A was small had good water repellency. High surface resistivity. In Comparative Example 5 in which the fluorine atom content was less than 25%, the surface resistivity was good, but the water repellency was poor.

[0054]

As described above, according to the aqueous composition of the present invention, by combining a specific cation-modified copolymer and a specific fluorine atom-containing polymer, the cured antistatic film can be charged. It is not only excellent in prevention, but also excellent in warm water resistance and water repellency.

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Claims (3)

[Claims] An aqueous composition containing the following components A and B, wherein the weight ratio of the component A to the total amount of the components A and B is 0.05 to 0.50. . A: 70 to 99 mol% of an ethylene structural unit represented by the formula (1) and an acrylate structural unit 0 to 15 represented by the general formula (2)
Mol%, and acrylamide structural units 1 to 3 represented by the general formula (3)
0 mol%, and the weight average molecular weight is 1,000 to 8
A cation-modified copolymer having a molecular weight of 10,000. Embedded image (Wherein, R1 represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, R2 represents an alkylene group having 2 to 8 carbon atoms,
3, R4 and R5 each independently represent an alkyl group having 1 to 12 carbon atoms, an arylalkyl group having 7 to 12 carbon atoms or an alicyclic alkyl group having 6 to 12 carbon atoms, and X is a halogen atom, CH3OSO3, C2H5OSO3 or R6SO3
Wherein R6 is an alkyl group having 1 to 12 carbon atoms,
An arylalkyl group having 7 to 12 carbon atoms or 6 to 1 carbon atoms
2 represents an alicyclic alkyl group. B) Polymer or copolymer containing 25% or more by weight of fluorine atoms. 2. The aqueous composition according to claim 1, comprising 2 to 40% by weight of the component A and 5 to 40% by weight of the component B. 3. An antistatic film containing the components A and B according to claim 1 or 2, wherein the weight ratio of the component A to the total amount of the components A and B is 0.05 to 0.50. .