JPH04234442A - Production of permanently antistatic molding - Google Patents

Abstract

PURPOSE:To obtain an antistatic molding excellent in surface hardness and durability. CONSTITUTION:An organic material containing a polymer, which is composed primarily of a functional monomer having two or more acryloyloxy or methacryloyloxy groups in the molecule, at least in the surface layer section is irradiated with an ultraviolet ray with a wavelength of 300nm or less. The resulting organic material is treated with an alkali to form 0.02muol/cm<3> of the acidic groups in the surface layer section, covered with a solution comprising silicon alkoxide-tin chloride-ammonium fluoride and/or antimony chloride compound to form a thin film which is heat-treated.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing permanently antistatic molded articles having excellent durability. The molded product obtained by the present invention is used in various industrial fields such as architectural interiors, electronics, automobiles, and optics.

0002

BACKGROUND OF THE INVENTION Polymer compounds generally have very good electrical insulation properties, and therefore, when they are rubbed or when stacked films are peeled off, they easily become charged to tens of thousands of volts or more. Many methods are known for preventing charging of polymer compounds that are easily charged. For example, there are two methods: applying an antistatic agent to the outside of the molded product to form a film of the antistatic agent on the surface layer, lowering the surface resistance and increasing charge leakage; One example is a method in which the material is allowed to ooze out onto the surface layer of the molded product, forming a monomolecular film, increasing conductivity through moisture absorption and exhibiting an antistatic effect. Another example is a method of chemically treating the surface of a polymer compound to introduce a functional group to prevent charging.

0003

[Problems to be Solved by the Invention] Conventional antistatic methods have rarely produced molded products that have excellent surface hardness and antistatic properties. That is, in order to improve the surface hardness of a molded article, a method is generally used in which the molded article is coated with a compound having high hardness. However, in this method, when attempting to impart antistatic properties, a decrease in surface hardness cannot be avoided, and it has been extremely difficult to satisfy both performances.

0004

[Means for Solving the Problems] The present inventors recognized the problems of the prior art, and as a result of intensive study, the present inventors have developed a method for polymerizing the surface of a polymer obtained by polymerizing monomers of a specific composition under specific conditions. By hydrolyzing it to form a multilayered acidic group on its surface layer, and then surface-treating it with a specific compound, we succeeded in producing an extremely durable antistatic molded product.

[0005] The present invention provides two or more (meta) molecules in one molecule.
An organic material having at least its surface layer a polymer mainly composed of a polyfunctional monomer having an acryloyloxy group is irradiated with ultraviolet rays containing a wavelength of 300 nm or less and subjected to alkali treatment to coat the surface layer of the organic material. This invention relates to a method for producing a permanently antistatic molded article, which comprises forming an acidic group, depositing a solution consisting of silicon alkoxide, tin chloride, ammonium fluoride, and/or antimony chloride to form a thin film, and heat-treating.

[0006] In the present invention, the term "molded article" means an article having a certain shape. Moreover, "(meth)acryloyl" means acryloyl or methacryloyl.

[0007] In the present invention, 2
Examples of polyfunctional monomers having at least 2 (meth)acryloyloxy groups include 1,4-butanediol diacrylate, 1,6-hexanediol diacrylate, neopentyl glycol diacrylate, ethylene glycol diacrylate, and triethylene glycol. Diacrylate, tripropylene glycol diacrylate, dipropylene glycol diacrylate, 3-methylpentanediol diacrylate, diethylene glycol bisβ-acryloxypropionate, trimethylolethane diacrylate, trimethylolpropane triacrylate, pentaerythritol triacrylate, Pentaerythritol hexaacrylate, tri(2hydroxyethyl)isocyanate diacrylate, pentaerythritol tetraacrylate, 2,3-bisacryloyloxyethyloxymethyl [2,2,1]heptane, poly 1,2-butadiene diacrylate, 1, 2
-bisacryloyloxymethylhexane, nonaethylene glycol diacrylate, tetradecane ethylene glycol diacrylate, poly 1,2-butadiene dimethacrylate, ethylene glycol dimethacrylate,
Triethylene glycol dimethacrylate, 10 decane diol dimethacrylate, 3,8 bisacryloyloxymethyl tricyclo(5,2,10) decane hydrogenated bisphenol A diglycidyl ether diacrylate, 2,2 bis(4-acryloyloxy dimethacrylate) ethoxyphenyl)propane, 1,4 bis(acryloyloxymethyl)cyclohexane, hydroxypiparic acid ester neopentyl glycol diacrylate, bisphenol A diglycidyl ether diacrylate, EO modified bisphenol A diacrylate, 2-2″ bis(4- (methacryloyloxydiethoxyphenyl)propane, etc.In addition, when a monofunctional monomer such as methyl methacrylate is used alone instead of a polyfunctional monomer, that is, in the case of polymethyl methacrylate, , the formation of acidic groups is minimal and is not within the scope of the present invention.

[0008] These polyfunctional monomers may be used alone or as a mixture to form a polymer, but depending on the case, they may be used as a copolymer with monofunctional monomers other than those mentioned above. The organic material according to the present invention includes a molded product made of the above polymer alone and a molded product obtained by polymerizing and laminating the above polymer onto the surface of various organic material substrates.

[0009] In the surface treatment of the present invention, a single molded product may be used, but it is more preferable to polymerize and laminate it onto the surface of various organic material base materials, so that the surface characteristics in addition to the base material characteristics are improved. This is desirable in that the scope of use of this technology can be expanded because it is added.

[0010] Here, the various organic material base materials include, for example, acrylic resin, polycarbonate resin, polyester resin, polystyrene resin, vinyl chloride resin, and other known resins.

By performing the following surface treatment on these molded products, the amount of acidic groups in the surface layer was reduced to 0.02 μmol.
/cm2 or more. First, a molded product having two or more (meth)acryloyloxy groups in one molecule is irradiated with light containing ultraviolet light. The purpose of irradiation with ultraviolet light is to cleave a portion of the molecular chains of the polymer that constitutes the surface layer. For this reason, for example, it is desirable to use an ultraviolet light having the energy (approximately 4 eV or more) necessary to break molecular chain bonds. As a specific ultraviolet wavelength range, it is necessary to irradiate in a wavelength including short wavelength ultraviolet rays of 300 nm or less, for example. A more specific example would be a germicidal lamp.20
It is preferable to use a light source that contains a large amount of ultraviolet light with a wavelength around 0 to 260 nm. The irradiation amount may be set to a condition that satisfies the scope of the present invention, since the intermolecular bond energy differs depending on the composition of the polymer used.

[0012] Since the affinity for basic dyes is hardly improved by the above-mentioned ultraviolet irradiation treatment alone, an alkali treatment is subsequently performed. The alkali treatment here refers to treatment with an alkaline aqueous solution. Specifically, examples thereof include aqueous solutions of sodium hydroxide, potassium hydroxide, etc., and alkaline aqueous solutions containing various solvents. The conditions for alkaline treatment cannot be unconditionally defined because they vary depending on the composition and form of the object to be treated, the desired performance, the amount of ultraviolet irradiation, etc., but for example, in the case of sodium hydroxide, the concentration is 0.1 to 50% by weight, preferably 1-30%
The temperature is 0 to 100°C, preferably 20 to 80°C, and the time is 0.01 to 100 hours, preferably 0.1 to 10 hours.

The organic material subjected to the alkali treatment may then be washed with water and, if necessary, further neutralized and washed with an inorganic acid or an organic acid. The organic material thus obtained has a surface layer of 0.0
2 μmol/cm2 or more of acidic groups are generated. Here, the amount of acidic groups refers to the number of moles (μmol) that the basic dye can adsorb per unit area of the surface of the polymer referred to in the present invention.
/cm2) and is a value determined by the following measurement method.

(1) Prepare a 0.1N sodium acetate buffer (pH 4.5). (2) A solution with a methyl violet concentration of 1.0 g/l is prepared using the buffer solution of (1). (3) A 50 x 50 mm2 plastic molded article is immersed in this solution for 48 to 72 hours. (4) Wash the plastic molded product with water. (5) Wipe off moisture. (6) Immerse in n-dimethylformamide solution to extract and dissolve the dye. (7) Measure the absorbance of the dye extract using 589 nm light. (8) Separately, a calibration curve of dye concentration is obtained from a dye solution dissolved in n-dimethylformamide solution, and the basic dye concentration per unit area of the plastic molded article is calculated.

[0015] A large amount of acidic groups are formed on the surface layer of the molded product thus obtained, and since the layer in which acidic groups are formed is limited to the surface layer, the hardness of the layer containing a large amount of polyfunctional (meth)acrylate monomer is is almost unchanged from before treatment.

The obtained molded product is then treated with a silicon alkoxide-tin chloride-ammonium fluoride and/or antimony chloride compound. In the above compound, the silicon alkoxide is represented by the general formula Si(OR)n. Here, R is an alkyl group, and n is the oxidation number of the metal element. Preferred silicon alkoxides in the present invention include, for example, tetraethoxysilane Si (
OC2H5)4, tetramethoxysilane Si (OCH3
)4, etc. Generally, the above compound is used after being dissolved in a solvent.

[0017] The method of adhering to the molded product is not particularly limited, but it may be applied by a known method such as spraying, dipping, roller coating, spin coating, etc., to form a thin film on the surface of the molded product, and then heat-treated. By going through these series of steps, the acidic groups generated on the surface layer of the molded product and the compound coordinated therewith form a thin film, so that a permanent antistatic molded product can be obtained.

[0018] Antistatic property as used in the present invention means that the surface resistance value of the molded product is lower than 1011Ω.
105Ω by appropriately selecting the composition ratio of the compound
It is also possible to do the following. The surface resistance value is 2
In an atmosphere of 0°C x 65% RH, the normal four-point probe method (
This is a value measured in accordance with JIS-H0602).

The above compound is silicon alkoxide 60.
0-95.0% by weight, tin chloride 25.0-4.8% by weight
, ammonium fluoride and/or antimony chloride 10~
Preferably, the compound is used within a composition range of 0.2% by weight. In addition, as a solvent, alcohols such as ethyl alcohol, methyl alcohol, isopropyl alcohol, butyl alcohol, dimethyl formamide, methyl ethyl ketone, acetone, ethyl acetate, butyl acetate, water, and small amounts of polycondensation of hydrochloric acid, sulfuric acid, acetic acid, ammonia, etc. Accelerators may also be added. It is preferable to mix 0.5 to 70% by weight of the above compound in these solvents.

However, the viscosity changes depending on the reaction state of the polycondensation of the compound mixed in the solvent, and the thickness of the film adhered to the surface of the molded article differs. For this reason, conditions may be set as appropriate by selecting the composition of the compound, the selection of the solvent, etc., and the conditions are not limited to the present invention. The preferred thickness of the film to be adhered to the surface of the molded product is 50 Å to 3 μm. If the thickness is less than 50 Å, the surface resistance value will increase, and if the film thickness exceeds 3 μm, the film will have a high hardness due to the difference in thermal expansion coefficient and mechanical strength between the molded organic material and the compound. Defects such as cracks occur.

[0021] The heat treatment of the present invention is carried out at a temperature in order to improve the coordination between the compound and the acidic groups formed on the surface layer of the molded article, and is preferably in the range of 50°C to 130°C. The upper limit temperature is not particularly limited as long as it is below the deformation temperature of the molded product used.

[0022]

Examples Example 1 Monomer mixture: 10% by weight of dipentaerythritol hexaacrylate, 20% by weight of equimolar condensate of succinic acid/trimethylolethane/acrylic acid, 5% by weight of tetrahydrofurfuryl acrylate, photoinitiator "Darocur 1173" A polymethyl methacrylate resin plate with a thickness of 3 mm was immersed in a solution containing 1.2% by weight of ``Merck &Co.'' (manufactured by Merck & Co., Ltd.), 34% by weight of isopropanol, and 30% by weight of toluene, and then slowly immersed at a speed of 0.2 cm/sec. A coating film of the composition was laminated on the surface of the pulled resin plate. This was maintained at a temperature of 35°C, and in that state, at a distance of 15 cm from both sides of the resin plate,
840mJ/c using a high pressure mercury lamp with 65nm
A cured film with a thickness of 3.5 μm was formed at an irradiation dose of m2. The surface layer of the obtained resin plate is JIS K5
The pencil hardness was 5H, defined as 400. Then, using a low-pressure mercury lamp with a central wavelength range of 254 nm,
Irradiation was performed at an irradiation dose of 0 mJ/cm2. The surface layer of the obtained resin plate maintains a pencil hardness of 5H, and the amount of acidic groups measured with the basic dye methyl violet is 0.
．． 012 μmol/cm2, which did not satisfy the present invention. Therefore, the irradiated resin plate was immersed in a 20% by weight aqueous sodium hydroxide solution at room temperature for 3 hours, washed and dried, and then immersed in a 0.05% by weight sulfuric acid aqueous solution at room temperature for 1 minute, washed and dried.

The obtained resin had an acidic group content of 0.05 μmol/cm 2 only on the surface irradiated by the low-pressure mercury lamp, had excellent stainability with basic dyes, and maintained a pencil hardness of 5H.

[0024]The molded product was subjected to antistatic treatment according to the following method. (a) Preparation of compound solution Tetraethoxysilane 4.0g Stannic chloride 5.0g Ammonium fluoride 0.5g Isopropyl alcohol 1000g Water
10g hydrochloric acid
A compound is prepared by stirring 1 g of a mixed solution at room temperature for 1 hour.

(b) The molded product was immersed in the above prepared solution for 5 minutes, pulled up at a speed of 10 cm/sec, and then
A drying process is carried out for 30 minutes at a temperature of .degree. The surface electrical resistance value of the obtained molded product was 5×106 Ω, and further 20
Even in an atmosphere of 45% RH and 45% RH, it exhibited a resistance of 5 x 106 Ω, and had stable antistatic ability against changes in humidity.

[0026] Even after washing with detergent and running water, there was no change in the surface electrical resistance value, and a molded product with excellent antistatic properties was obtained, which was satisfactory.

Example 2 Monomer mixture: 8.5% by weight of trimethylolethane diacrylate, 60% by weight of 1,6-hexanediol diacrylate, succinic acid/trimethylolethane/
A mixed solution consisting of 20% by weight of an equimolar condensate of acrylic acid and 1.5% by weight of the photoinitiator benzoin ethyl ether is applied to one side of a 3 mm thick polycarbonate plate using a roll coater to form a coated film of the composition on the surface. were laminated. This was placed in a quartz tube kept at a temperature of 40°C and nitrogen gas was passed through it, and held for 3 minutes.
Using a high-pressure mercury lamp with a high-pressure mercury lamp, irradiation was performed at a dose of 800 mJ/cm 2 to form a cured film with a thickness of 18 μm. The surface layer portion of the obtained resin plate had a JIS K5400 pencil hardness of H. Next, irradiation was performed using a low-pressure mercury lamp having a center wavelength of 254 nm at an irradiation dose of 4000 mJ/cm2. The surface layer of the obtained resin plate maintains a pencil hardness of H, and the amount of acidic groups measured by dyeing with basic dye methyl violet is 0.015 μmol / cm.
2, which did not satisfy the present invention. Therefore, the irradiated resin plate was immersed in a 10% by weight aqueous sodium hydroxide solution at room temperature for 10 hours, washed with water, dried, and then immersed in a 0.1% by weight hydrochloric acid aqueous solution at room temperature for 5 minutes, washed with water, and dried.

The obtained resin had an acidic group content of 0.12 μmol/cm2 only on the surface irradiated by the low-pressure mercury lamp, and maintained a pencil hardness of H.

The molded product was subjected to antistatic treatment according to the following method. (a) Preparation of compound solution Tetraethoxysilane 150g Ethyl alcohol 150g Water
20g stannic chloride 5g antimony trichloride 1g salt
acid 1
A mixed solution of g is stirred at room temperature for 1 hour to prepare a compound.

(b) After immersing the molded product in the above prepared solution for 5 minutes and pulling it up at a speed of 10 cm/sec,
A drying process is carried out for 30 minutes at a temperature of .degree. The surface electrical resistance value of the obtained molded product was 2×107 Ω, and further 20
It exhibited a resistance of 2×10 7 Ω even in an atmosphere of 45% RH and had stable antistatic ability against changes in humidity.

Even after washing with detergent or running water, there was no change in the surface electrical resistance value, and a molded product with excellent antistatic properties was obtained, which was satisfactory.

[0032]

Effects of the Invention The molded product obtained by the method of the present invention has a large amount of acidic groups and compounds coordinated thereon attached to the surface layer, so it exhibits extremely durable antistatic properties and is easily washed with water. There is very little reduction in antistatic effect due to friction solvent treatment, etc.

Claims (1)

[Claims] 1. A method for producing a permanently antistatic molded product, comprising: a polymer mainly composed of a polyfunctional monomer having two or more acryloyloxy groups or methacryloyloxy groups in one molecule; The organic material contained in the organic material is irradiated with ultraviolet rays having a wavelength of 300 nm or less and subjected to alkali treatment to form acidic groups on the surface layer of the organic material. A method characterized by depositing a solution consisting of a system compound to form a thin film, and then heat-treating.