SURFACE COATING COMPOSITION

Technical Field

[1] The present invention relates to a surface coating composition for improvement of anti-soiling and weatherability, and more particularly, to a surface coating composition for improvement of anti-soiling and weatherability, by which contaminants such as dust are not deposited on a surface of a base member which is processed by the surface coating composition, due to a charge prevention property, water drops are not formed on a surface of the base member due to a hydrophilic property while a thin water film is formed so that deposited contaminant materials can be easily removed, and weatherability can be improved by using an ultraviolet stabilizer and an absorbent. Also, the present invention relates to a surface coating composition for undercoating to prevent deformation of the base member and obtain a stronger adhesive strength.

Background Art

[2] In the present invention, when a base member such as Polymethyl methacrylate

(PMMA) or polycarbonate which is difficult to adhere is to be coated, a silicon-acryl copolymer is fabricated and added by 5 part by weight or less to the whole composition to improve the adhesive strength.

[3] The base member includes ceramic, glass, metal, alloy, plastic, textile, cloth for tent (Tarpaulin), non-woven fabric, vinyl, an exterior wall of a building, a stone con¬ struction, PVC, and so forth. When the base member is coated with a surface coating composition fabricated according to the present invention, contaminants on a surface of the base member are removed and the surface coating composition is adhered to the base member in a method such as dip coating, spin coating, bar coating, roll coating, or spray coating and then cured at 120-140 ⁰ C within ten minutes so that an anti-soiling film can be obtained.

[4] When the surface coating composition of the present invention is not processed, city smoke floating in the air, dust and earth particles, or combustion products is smoothly deposited on various base members in sunny weather. Such deposits or floating dusts are washed out by rain and flows down along the surface of the base member so that the contaminants adhere on the surface thereof. Thus, as time passes, the various base members exposed to the air lose the intrinsic properties of the surface and a surface contamination problem becomes serious. Conventional anti-soiling and weatherability coating agents or paint mostly use fluorochemicals or silicon-based resin. However, since the fluorochemicals has the least attraction force between molecules and a low surface energy, the adhesion of the contaminants cannot be prevented.

[5] For example, -CF 3 has a critical surface tension of 6 dyne/cm which is one fourth the surface tension of a methyl radical (-CH ) that is 22-24 dyne/cm. Thus, -CF exhibits superior hydrophobic and oil repellent effects. However, since the anti- soiling coating agent cannot be formed of only pure fluorochemicals, acryl-based resin or silicon-based resin need to be used simultaneously so that the anti-soiling effect is de¬ teriorated.

[6] For example, Japanese Patent Publication No. sho 60-21686, Japanese Laid-open

Patent Publication No. hei 3-121107, and Japanese Lai-open Patent Publication No. hei 4-279612 disclose a copolymer of fluorolefin and vinylether or vinylesther. The copolymer is combined with a curing agent such as isocyanate or melamine and cured at a low temperature or at a room temperature so that a film exhibiting a superior weatherability is formed.

[7] However, when the film is exposed to the outside, the contaminants in the air or rain can easily adhere to and are deposited on the film. Also, to improve a property of washing out a carbon contaminant or a magic contaminant, a method of reacting or mixing fluorochemicals and silicon-based resin, and a compound fabricated by adding monomeric or oligomeric organo ceylan to water with a catalyst, hydrolyzing the same, and adding fluorochemicals, which is disclosed in U.S. Patent No. 3429845, have been suggested. However, these methods do not have an anti-soiling effect. Conventionally, to prevent the contamination of the surface of various base members exposed to the air, hydrophobic paint such as polytetrafluoroethylene (PTFE), tetra-fluoroethylene hexa- fluoro-propylene copolymer (FEP), polyvinylidene fluoride (PVDF), tetra- fluoroethylene -perfluor alkoxy copolymer (PFA), or polyvinyl fluoride (PVF) has been regarded to be preferable. Recently, since there are many contaminants including a large quantity of a hydrophobic ingredient, it is preferable for the surface of a base member coated with a surface coating agent to remove the contaminants to exhibit a hydrophilic property. Disclosure of Invention

Technical Problem

[8] To solve the above and/or other problems, the present invention provides a surface coating composition for improvement of anti-soiling and weatherability, in which the property of a base member is stably maintained for a long time by providing anti- soiling and weatherability on a surface of the base member to be processed so that con¬ taminants in the air or due to rain are difficult to be attached to or deposited on the base member, the contaminants can be easily removed once the base member is con¬ taminated, and the surface of the base member is not discolored by an ultraviolet ray or damaged. Also, the present invention relates to a surface coating composition for un-

dercoating the surface of the base member to prevent deformation of the base member and obtain a stronger adhesive strength.

Technical Solution

[9]

[10] The present invention relates to a surface coating composition for improvement of anti-soiling and weatherability which provides anti-soiling and weatherability when coated on the surface of the base member, to prevent contamination on the surface of the base member exposed to the air due to city smoke or rain and discolor and damage by an ultraviolet ray included in sun rays. According to the present invention, a surface coating composition for improvement of anti-soiling and weatherability in a transparent state includes various additives such as organic alkoxysilane, silicon-acryl copolymer, metal oxide, discharger, and surface active agent, and two or more solvents for adjustment of curing speed.

[11] Also, although the surface coating composition can be used without special pre- treatment to various base members, to prevent deformation of the base member and obtain a stronger adhesive strength, it can be coated after undercoating the surface of the base member using a surface coating agent for undercoating including additives such as silicon-based resin, silicon-acryl copolymer, metal oxide such as silica and alumina, acid catalyst, and curing catalyst, and an organic solvent. That is, after removing contaminants on the surface of the base member to be processed, the surface coating composition for undercoating is coated on the surface of the base member and cured. Then, the surface coating composition for improvement of anti-soiling and weatherability in a transparent state is coated by dip coating, roll coating, spin coating, spray coating, or bar coating, and dipped to be cured, so that anti-soiling and weatherability are obtained and simultaneously deformation of the base member is prevented and a stronger adhesive strength is obtained after coating.

[12] Also, without performing the undercoating using the surface coating composition for undercoating, superior anti-soiling and weatherability are obtained by solely coating the surface coating composition for improvement of anti-soiling and weatherability according to the present invention and curing the same so that the thickness of coating is 0.1 - 1 m m.

[13] According to an aspect of the present invention, a surface coating composition for improvement of anti-soiling and weatherability of a base member formed of plastic, ceramic textile, cloth for tent, and metal, which is used by being coated on a surface of the base member, comprises polysiloxan solution of 4.0-25 part by weight obtained by mixing and reacting silicon-based resin of 3.0-12.5 wt% including alkoxysilane as a fundamental ingredient, metal oxide of 7.0-10.0 wt% in which at least one ingredient from a metal oxide group consisting of silica, alumina, and titania is formed in sol and

dispersive form, a reaction speed control agent of 40-42.5 wt% such as isopropanol for controlling a reaction speed, a reaction and curing promotion catalyst of 40-42.5 wt% such as acetic acid and dibutyltindilaurate, and a solvent of 40-42.5 wt% comprising ethanol, isopropanol, butanol, and toluen in a weight ratio of 5:5:2:3 for storage stability and solid content control, silicon-acryl-based copolymer of 0.7-5.0 part by weight, titan oxide solution of 14-20 part by weight having a solid ingredient of 10 wt% including optical catalyst in sol and powder states, a charge prevention agent of 0.1-0.2 part by weight, an ultraviolet stabilizer of 0.1-0.3 part by weight, and a surface active agent of 0.1-0.5 part by weight which are additives, an organic solvent of 55-60 part by weight comprising methanol, ethanol, isopropanol, and butanol which are low boiling and high boiling alcohol in a weight ratio of 3:3:3:1, and water of 5.0-10 part by weigh that is a typical solvent.

[14] The silicon-based resin and silicon-acryl-based copolymer is a mixture of two or more of alkoxysilane including tetrametoxysilane, metyltrietoxysilane, tetrapropoxysilane, tetrabutoxysilane, silanol, methyltrimetoxysilane, methyltri- etoxysilane, methyltributoxysilane, dimethyldimetoxysilane, ethyltrimetoxysilane, ethyltrietoxysilane, ethyltripropoxysilane, penyltrimetoxysilane, penyltrietoxysilane, penyltributoxysilane, n-propyletoxysilane, n-propyltripropxysilane, γ - glycoxydoxypropyltrimetoxysilane, and γ -acryloxypropyltrimetoxysilane, a resultant fabricated by partial hydrolysis and dehydrated condensation polymerization thereof are used, and, when the base member that is polycarbonate is difficult to adhere, monomer including methylmetaacrylate (MMA), metaacryl acid (MAA), 2-hydroxy ethylmetaacrylate, and 3-trimetoxy sirylpropyl metaacrylate is copolymerized and a mixture of two or more compositions copolymerized with silane coupling agent or alkoxysilane are used. The weight mean molecule amount of the fabricated silicon- acryl-based copolymer is between 10000-30000.

[15] When the weight mean molecule amount is not more than 10000 and the fabricated silicon-acryl-based copolymer is added to the surface coating agent, since it is not ap¬ propriately cured in the curing conditions of a lower temperature and a short time, a firm coating film cannot be formed and, as reaction to polysiloxane occurs, a stable liquid status cannot be maintained for a long time. Also, when weight mean molecule amount is not less than 10000, the coating film becomes thick and opaque so that metal oxide exhibiting a hydrophilic property is completed coated and thus a hydrophilic effect is deteriorated.

[16] The metal oxide (2) has a particle size of 3-500 nm, preferably, 5-50 nm, and one or more of amorphous silica sol having a solid ingredient of 2-40wt%, anatase and amorphous titanium sol and powder dispersive form, and alumina sol of pseudo- boehmite can be used. Since the solid acid such as alumina and silica improves the hy-

drophilicity effect by increasing a hydrogen combining ingredient of a surface energy of titania, it must be added and simultaneous increases a contact angle with oil on the surface of the solid.

[17] Use of a catalyst is required to promote a polymerization reaction and the shelf stability of coating solution. The catalyst includes acid such as nitric acid, hydrochloric acid, sulfuric acid, phosphoric acid, acetic acid, oxalic acid, maleic acid, and succinic acid, base such as ammonia water, sodium hydroxide, and potassium hydroxide, and organic metal compound such as dibutyltindilaurate, dibutyltinacetate, dioctylt- inmaleate, and tetraisopropyltitanate. As one having a superior property of shelf life and curing speed balance, one or more catalysts such as natrium acetate, potassium acetate, 4 ammonium carboxylate, trimethylamine, and pyridine which are buffer latent polymer catalysts can be used.

[18] The additives further comprise a charge preventing agent, a surface active agent, a catalyst, and an ultraviolet stabilizer. Indium-tin oxide, titanium having a needle-like shape, potassium titanate as the charge preventing agents are used to form a conductive film. An ultraviolet absorbing agent and an optical stabilizer include cerium oxide, benzotriazole, benzophenone, anilid hydroxide, cyanoacrylate-based compound, and hindadamine-based compound.

[19] Also, the surface active agent is used to obtain an effect of maintaining initial hy- drophilicity and wettability of a surface after existing weatherability surface coating having a low boundary surface tension such as fluorine resin is performed. One or more surface active agents such as cation, anion, non-ion, and bi-ion-based surface active agents can be used. For example, sulfonic acid polyoxiethylene alkylpenyl ether ammonium salt, fatty acid natrium soap, diotylsulfuric succinic acid, etylhexy- lalkylsurfuric natrium, sorbitan oleate, sorbitan sesquioleate, polyether-modified silicon, polyester-modified silicon, glycerol stealate, alkylalkylol amid, laurin acid dimethanol amid, polyoxyethylene octadecyl amine, dimethylalkyl betaine, akylglycerin, amid betaine, imidasolin, alkylpropylenediamine acetic acid salt, polyglycerin fatty acid estere, octadecyl dimethyl benzyl ammonium chloride.

[20] Water and organic solvent are preferable for the solvent. The organic solvent must include two or more of alcohols such as methanol, ethanol, isopropanol, n-propanol, isobutanol, octanol, ethyleneglycol, and propyleneglycol, and acetone, methylethylketon, ethylacetate, propylacetate, butylacetate, 2-methoxy ethylacetate, di- ethyleneglycol, ethyleneglycol alkylethere, diethyleneglycol alkylethere, propy¬ leneglycol alkylethere, and glycerin.

[21] The composition is composed of an ingredient providing hydrophilic and charge preventing effects and an ultraviolet absorption feature as the surface coating composition for improvement of anti-soiling and weatherability. Since the composition

exhibits superior adhesive strength and film strength on various base members, superior performance can be obtained by solely coating the composition on various base members.

[22] According to another aspect of the present invention, a surface coating composition for undercoating, which is used by being undercoated on a surface of a base member formed of plastic, ceramic textile, cloth for tent, and metal for prevention of dete¬ rioration of the base member and improve adhesive strength, comprises polysiloxan solution of 80-95 part by weight obtained by mixing and reacting silicon-based resin of 5.0-15.0 wt% including alkoxysilane as a fundamental ingredient, metal oxide of 12.0-15.0 wt% in which at least one ingredient from a metal oxide group consisting of silica, alumina, and titania is formed in sol and dispersive form, a reaction speed control agent of 27-30 wt% such as isopropanol for controlling a reaction speed, a catalyst of 0.5-1.0 wt% such as acetic acid, and an organic solvent of 45.5-49.0 wt% including ethanol, isopropanol, butanol, and toluen in a weight ratio of 5:5:2:3 for storage stability and solid content control, silicon-acryl-based copolymer of 4-14 part by weight, trimethylamin of 0.1-1.0 part by weight that is a curing catalyst, and water of 0.9-5.0 part by weigh that is a typical solvent.

[23] The detailed specifications of the silicon-based resin, the silicon-acryl-based copolymer, the metal oxide, and the catalyst are the same as those described in the surface coating composition for improvement of anti-soiling and weatherability.

[24] According to the present invention, by the surface coating composition for im¬ provement of anti- soiling and weatherability coated on the top upper surface of the base member and the surface coating composition for undercoating undercoated on the surface of the base member according to the situation, continuous contamination in the air is prevented and a self-purification effect is exerted so that surface coated ceramic, glass, metal, alloy, plastic, textile, cloth for tent (Tarpaulin), non- woven fabric, vinyl, an exterior wall of a building, a stone construction, PVC, plane, train, and car body, and so forth can maintain their intrinsic features for a long time without special cost investment.

[25] Also, when the base member is ceramic, glass, metal, alloy, an exterior wall of a building, a stone construction, plane, train, and car body, without using the surface coating composition for undercoating, a high adhesive strength, anti-soiling, and weatherability can be obtained. By adjusting the quantity of silicon compositions and silicon-acryl-based copolymer and a solvent, curing is possible at the room temperature so that it can be used for various purposes.

Advantageous Effects

[26] According to the surface coating composition for improvement of anti-soiling and weatherability according to the present invention, the charge prevention feature and the

anti- soiling feature due to a hydrophilicity effect is remarkably superior to the con¬ ventional anti-soiling coating agent. Since an inorganic- and organic- based ultraviolet absorbing agent is used, weatherability is improved. Also, the present invention provides effects of preventing deterioration of the base member and enforcing an adhesive strength, and exerting the intrinsic features of the base member for a long time. By forming a transparent thin film, the present invention can be used in various purposes in a variety of fields without special limitation. The present invention can solve the problems of the conventional technology in the anti-soiling and weatherability and simultaneously prevent deterioration of the base member, provide a strong adhesive strength, and improve strength of the film by the composition for un- dercoating.

Best Mode

[27] Hereinafter, the present invention will be described in detail through the em¬ bodiments of the present invention and the comparative examples. Since the em¬ bodiments are merely proposed for easy understanding of the present invention, the present invention is not limited by the embodiments.

[28] First, to fabricate the surface coating composition for improvement of anti-soiling and weatherability, TiO is fabricated by dispersing product name P-25 provided by Degusa, a German company, that is optical catalyst powder in distilled water at 10 part by weight. The silicon-acryl-based copolymer and the surface coating composition for undercoating undercoated on the surface of the base member are fabricated as follows. Commercial products are used as other additives.

[29] For fabrication of silicon-acryl-based copolymer for improvement of adhesive strength:

[30] A mixture of methylmeta-acrylate 35g, metaacryl acid 1Og, 2-etoxyethanol 20Og, butantiol 0.05g, and azobisisobutylonitril 1.2g is agitated for 3 hours at 5O ⁰ C under nitrogen gas. γ -glycoxydoxipropyltrimetoxysilane 1Og is added to diacetonealcohol 50g and 2-etoxyethanol 50g in a 500ml round flask and agitated. The resultant is added to the above solution and agitated for 12 hours at 75 ⁰ C to fabricate a copolymer. The number- average molecular weight of the fabricated copolymer is 16,840, the , weight- average molecular weight is 21,250, and yield of polymer is 85%.

[31] For fabrication of surface coating composition for undercoating;

[32] Metyltrietoxysilane 500g, tetrametoxysilane 150g, and γ -aminopropyletoxysilane

80g are mixed in a 10-liter reactor having a cooler and an agitator attached thereto and then isopropanol 2,00Og is added and heated and agitated for 1 hour at 50-60 ⁰ C. Silicasol (Ludox LS-30, 30 wt% SiO , Dupont) 90Og having an average particle size of 12 nm is slowly loaded down. After loading down is complete, acetic acid 65g is injected to react for 12 hours. Ethanol, isopropanol, butanol, and toluen are added in a

weight ratio of 5:5:2:3 in a total weight of 3,500g to obtain polysiloxane solution. After silicon-acryl-based copolymer 5 part by weight and water 4.8 part by weight that is solution are added to the polysiloxane solution 90 part by weight fabricated as above, trimethylamin 0.2 part by weight is added thereto as curing catalyst and cured for 3 days at the room temperature so that the surface coating composition for undercoating to be undercoated on the surface of the base member is fabricated.

[33] For fabrication of surface coating composition for improvement of anti-soiling and weatherabilitv:

[34] Metyltrimetoxysilane 1Og, tetrametoxysilane 1Og, and γ -aminopropyletoxysilane

5g are mixed in a 1 -liter reactor having a cooler and an agitator attached thereto and then isopropanol 150g is added and heated and agitated for 1 hour at 50-60 ⁰ C. Silicasol (Ludox LS-30, 30 wt% SiO , Dupont) 30g having an average particle size of 12 nm is slowly loaded down. After loading down is complete, acetic acid 3g is injected to react for 12 hours. Ethanol, isopropanol, butanol, and toluen are added in a weight ratio of 5:5:2:3 in a total weight of 150g to obtain polysiloxane solution. Dibutyltindilaurate Ig is added as curing catalyst and cured for 3 days at the room temperature to fabricate polysiloxane solution. Polysiloxane solution 10 part by weight fabricated as above, silicon-acryl-based copolymer 3 part by weight, titan oxide solution 20 part by weight having a solid ingredient 10 wt% which is obtained by dispersing product name P-25 provided by Degussa, a German company, which is an optical catalyst powder in solution using a hologenizer and an ultrasonic wave, sorbitan laurate 0.1 part by weight that is a surface active agent, tinuvin 5050 (Ciba) 0.2 part by weight that is an ul¬ traviolet stabilizer, methanol, ethanol, isopropanol, and butanol 57.7 part by weight which are organic solvent and low boiling and high boiling alcohol in a weight ratio of 3:3:3:1, and water 9.0 part by weight are added and agitated for 6 hours more at 25 ⁰ C so that the surface coating composition for improvement of anti-soiling and weatherability is fabricated.

[35] [Embodiment 1]

[36] The surface coating composition for improvement of anti-soiling and weatherability 50 part by weight fabricated as above and isopropanol 50 part by weight are mixed. The PVC Tarpaulin original cloth that is generally used as cloth for tent is cleaned with a dry cloth without a special pretreatment. The resultant of the mixture is coated one time using a bar coater (RDS #14, wet film thickness of 32 m m) and cured for 2 minutes at 130 ° C to obtain a sample. The test result is shown below in Table 1.

[37] [Embodiment 2]

[38] Prior to coating the surface coating composition for improvement of anti-soiling and weatherability on the Tarpaulin original cloth in the embodiment 1, the surface coating composition for undercoating fabricated as above is undercoated one time on

the Tarpaulin original cloth using a bar coater (RDS #12, wet film thickness of 27.4 m m) and cured for 2 minutes at 130 ° C. Next, the surface coating composition for im¬ provement of anti-soiling and weatherability 50 part by weight fabricated as above and isopropanol 50 part by weight are mixed and coated on the upper portion of the un- dercoated surface in the same manner as in the embodiment 1. As a result, a sample is obtained by coating the surface coating composition for undercoating on the surface of the Tarpaulin original cloth and the surface coating composition for improvement of anti- soiling and weatherability is coated thereon so that the surface coating composition is coated in a double layer. The test result is shown below in Table 1.

[39] [Comparative Example 1)

[40] The PVC Tarpaulin (Hanwhapolydreamer Co, Ltd.) original cloth that is a general cloth for tent which is not coated with the fluoric lacquer fabricated above is used as a comparative example. The test result is shown below in Table 1.

[41] [Comparative Example 2]

[42] After coating the PVC Tarpaulin original cloth that is a general cloth for tent one time with PVDF resin (G-73544) that is a commercialized product for improvement of anti-soiling and weatherability, using a bar coater (RDS #14), the coated PVC Tarpaulin original cloth is cured for 2 minutes at 130 ° C to obtain a comparative example. The test result in the following test method is shown below in Table 1.

[43] [Test Method]

[44] 1. Adhesive Feature

[45] The actions of strongly pressing a 3M scotch tape of 19 mm with fingers on the surface of the cloth for tent coated with the surface coating agent and detaching the same are repeated to determine the existence of separation of the surface. The de¬ termination is made according to a degree of separation. That is, cases in which a separated area is less than 5%, between 5-20%, and between 20-40% of the area where the tape is coated are A, B, and C, respectively. The other ranges are regarded as defect.

[46] 2. Degree of Gloss

[47] With respect to JIS K 5400, a gloss of a mirror surface at 60 degrees is measured using a glossmeter (IG-330, Horiba Ltd., Japan).

[48] 3. Hydrophilicity

[49] After the PVC Tarpaulin original cloth that is processed, or not processed, with the surface coating agent is exposed for 3 days outdoors to sun rays, a contact angle to water is measured using a contact angle meter (DSA 100, Kruss, Germany). The contact angle is measured after 30 seconds since water drops are dropped onto the surface of the sample through a microsyringe.

[50] 4. Anti-soiling Adhering Feature

[51] The PVC Tarpaulin original cloth is installed on an exposure plate inclined at 60 ° C toward the southeast direction on the top of a building and luminosity (L* value) after 6 months is measure. A difference (?ΔL*) from the initial luminosity is determined with respect to the standard of the anti-soiling adhering feature as follows. When ?ΔL* is 0-3, 3-5, 5-8, 8-10, and over 10, A, B, C,C, D, and E are respectively assigned.

[52] 5. Weatherability [53] After the coated PVC Tarpaulin original cloth is exposed for 2000 hours to UV-B lamp at 50+3 ° C using a weatherability promotion tester (QUV) by KS F 2274, the change in appearance such as the shape of the film, a change in the size, or color and gloss is observed. The determination is made by evaluating a 60 ° C inclined surface gloss maintenance rate (%) before and after the test.

[54] [Table 1] [55]

[56] As shown in Table 1, the embodiment 2 is determined to be most superior which is a sample in which the surface coating composition for undercoating is coated on the surface thereof and then the surface coating composition for improvement of anti- soiling and weatherability is coated thereon. The embodiment 1 is also determined to be very good which is a sample coated with only the surface coating composition for improvement of anti-soiling and weatherability. In contrast, the comparative examples 1 and 2 which are conventional products are determined to be very defective. The comparative example 1 which is a general sample that is not coated with a surface coating agent such as fluoric lacquer is determined to be very defective in the weatherability.

Industrial Applicability

[57] According to the surface coating composition for improvement of anti-soiling and weatherability according to the present invention, the charge prevention feature and the anti- soiling feature due to a hydrophilicity effect is remarkably superior to the con¬ ventional anti-soiling coating agent. Since an inorganic- and organic- based ultraviolet absorbing agent is used, weatherability is improved. Also, the present invention provides effects of preventing deterioration of the base member and enforcing an adhesive strength, and exerting the intrinsic features of the base member for a long time.