JPH0478673B2 - - Google Patents

Description

[Detailed description of the invention]

<Industrial Application Field> The present invention relates to a coating composition for surface modification (hereinafter simply abbreviated as composition). The surfaces of molded products made of synthetic resin materials such as polyethylene, polyvinyl chloride, polyester, polymethyl methacrylate, and inorganic materials such as glass are generally hydrophobic and have little affinity for water, so these molded products cannot be used as is. When you use
This may cause various problems. For example, when a film or sheet made of the synthetic resin material is used as a cover for an agricultural greenhouse, water vapor evaporating from soil or crops condenses on the surface of the film or sheet, forming a large number of water droplets. As a result, not only can the crops not be observed from the outside, but the optical transparency of the film or sheet is obstructed, resulting in significantly poor crop growth, and water droplets falling on the crops can cause disease. or Therefore, as a means of coating the surface of the molded article, there is a need for a composition that modifies the physical properties of the surface and prevents the adhesion of water droplets. The present invention relates to such a composition, and relates to a composition that can easily form a highly durable hydrophilic coating on the surface of the molded article. <Prior art and its problems> Conventionally, examples of using a water-soluble polymer as the composition, examples of using a homopolymer of a vinyl monomer having a hydrophilic polar atomic group in the molecule, and examples of using a homopolymer of a vinyl monomer having a hydrophilic polar atomic group in the molecule, and the composition as a whole are hydrophilic. There are also examples of using copolymers in which other monomers are copolymerized to the extent that properties can be imparted.
These are applied to the surface of the molded article in an aqueous or organic solvent system, and then cured or made insolubilized by various methods as required. but,
These conventional examples are generally inferior in the degree of expression of their intended effects compared to examples using water-dispersible sols such as those listed below. Conventionally, as the composition using a water-dispersible sol, there is an example of using a water-dispersible sol of an inorganic oxide such as alumina or silica. Specifically, examples of using a water-dispersible alumina sol include examples of using the alumina sol in combination with an anionic or nonionic surfactant (Japanese Patent Publication No. 49-32668), and cases of using a water-dispersible silica sol and a nonionic surfactant in combination. Examples of using water-dispersible silica sol include examples of using water-dispersible silica sol in combination with cationic and nonionic surfactants (Japanese Patent Publication No. 50-11348); Example of using anionic and nonionic surfactants together (Japanese Patent Application Laid-Open No. 55-56177),
Examples include using a surfactant and a silane derivative in combination (Japanese Patent Laid-Open No. 57-98578), and furthermore, treating the surface of the silica sol with aluminum ions and using a surfactant in combination (Japanese Patent Laid-Open No. 54-20979). be. However, when we try again with the above conventional examples that use water-dispersible sol, we find that in order to achieve the desired effect with the conventional examples, in many cases it requires troublesome drying, heating, etc. after applying it to the surface of the molded product. They require extensive management work, and all of them use surfactants with good surface activity as wetting agents.
There is a problem in that the expected effects lack long-term sustainability. The need for management work such as drying and heating after application is a major practical difficulty when applying to films and sheets that have already been applied to agricultural greenhouses, and there is no need for such management work. Another major drawback is that the long-term sustainability of the desired effects is poor. <Problems to be Solved by the Invention and Means for Solving the Problems> The present invention solves the above-mentioned conventional problems and enables the coating to be applied thinly and uniformly to the surface of a molded product without causing the above-mentioned repellency phenomenon. can,
There is no need for drying or heating after application.
The present invention provides a composition capable of forming a hydrophilic coating film with excellent durability on the surface. The present inventors have already discovered that, unlike other conventional methods that use a surfactant as a wetting agent in an inorganic colloidal sol, by using alumina sol together with a specific organic anionic compound that does not have surface activity, it is possible to control the sol after application. We are proposing a composition that maintains the desired effect for a long time even without any work (Japanese Patent Application Laid-Open No. 1983-
76462). As a result of intensive research in order to further improve the effect, the present inventors found that it is desirable to have an organic anionic compound that affects the particle properties of a mixture of alumina sol and a specific silica sol and adjusts its surface tension. It plays an excellent effect on the street,
In addition, they have discovered that a more excellent effect can be achieved by using a specific organic silane derivative, etc., and have completed the present invention. That is, the present invention uses the following A, B, and D, and by D, (A)/(B)=
9/1 to 2/8 [where (A) and (B) are the respective solid weights] The charges of the particles of the mixed inorganic colloidal sol are partially neutralized and partially hydrophobized to reduce the surface tension. The first invention relates to a coating composition for surface modification which is adjusted to 45 dynes/cm or more, and the following A, B, D and E are used, and by D and E, (A)/(B) = 9/ 1 to 2/8 [where (A) and (B) are the respective solid weights] The charges of the mixed inorganic colloidal sol particles are partially neutralized and partially hydrophobized to reduce the surface tension to 45 dynes. /cm or more. A: Alumina sol B: Acidic silica sol whose particle surface has a positive charge D: Water-soluble or water-dispersible organic anionic compound E: Organosilane derivative having 1 to 3 silanol groups in the molecule and/or this organosilane derivative The alumina sol of A is a so-called colloidal alumina, and those commercially available as aqueous dispersions can be used as they are. Specific examples include Alumina Sol 100, Alumina Sol 200, Alumina Sol 520 (all trade names, manufactured by Nissan Chemical Co., Ltd.), Cataloid AS-1, Cataloid AS-2 (all manufactured by Catalyst Kasei Co., Ltd.). product name) etc. Further, the acidic silica sol B has an average particle diameter of 5
~100 nm is preferred, and those commercially available as aqueous dispersions can also be used as they are. To give a specific example of this, Snowtex AK
(manufactured by Nissan Chemical Co., Ltd., product name), etc. Furthermore, there are many specific examples of the organic anionic compound D mentioned below. Aliphatic carboxylic acids such as acetic acid, butyric acid, caproic acid, caprylic acid, lauric acid, and oleic acid, aromatic carboxylic acids such as benzoic acid and P-toluic acid, and alkali metal salts and ammonium salts of these carboxylic acids. Alkyl sulfonic acids such as methanesulfonic acid, propanesulfonic acid, octylsulfonic acid, and dodecylsulfonic acid; sulfonic acids having ester groups such as diisobutylsulfosuccinic acid and dioctylsulfosuccinic acid; and furthermore, P-toluenesulfonic acid and dodecylbenzenesulfonic acid. aromatic sulfonic acids, and alkali metal salts and ammonium salts of these sulfonic acids. Alkali metal salts and ammonium salts of sulfuric esters such as isopropyl sulfate, octyl sulfate, and lauryl sulfate. Alkali metal salts and ammonium salts of phosphoric acid esters such as butyl phosphate, octyl phosphate, lauryl phosphate, etc. The organic silane derivative D is represented by the following general formula (), () or ().

【formula】 【formula】 [However, R ¹ , R ² , and R ³ are organic groups]

The above-mentioned organic silane derivatives and condensates thereof are usually prepared by preparing the corresponding raw material compounds such as silyl halides, alkoxysilanes, or γ-alkoxyalkoxysilanes in the presence of an appropriate inorganic acid, organic acid, or alkaline agent, or using only water. Although it can be obtained by hydrolysis, the present invention does not limit the manufacturing method. Specific examples of such raw material compounds include methyltrimethoxysilane, methyltriethoxysilane, vinyltrichlorosilane, vinyltriethoxysilane, and vinyltriethoxysilane, which correspond to the organic silane derivatives represented by the general formula () and their condensates. (methoxyethoxy)silane, vinyltriacetoxysilane, γ-chloropropyltripropoxysilane, γ-mercaptopropyltriethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-methacryloxypropyltriethoxysilane, phenyltrimethoxy There are silanes, etc., and there are also dimethyldimethoxysilane, γ-chloropropylmethyldimethoxysilane, γ-glycidoxypropylmethyldimethoxysilane, etc. that correspond to the organic silane derivatives represented by the general formula () and their condensates. ,
Further, there are trimethylchlorosilane, trimethylmethoxysilane, etc. that correspond to the organic silane derivatives represented by the general formula () and their condensates.
Any of these raw material compounds may be used alone or in a mixture of two or more. The present invention uses the above-mentioned three components A, B, and D or the above-mentioned four components A, B, D, and E in combination, but by adding D or E to the mixture of A and B. It may be adjusted, or B may be added after D or E is added to A, and in this case, E may be brought into a contact reaction with A or B. In the present invention, the adjustment target by D and E is (A)/
(B) is a mixed inorganic colloidal sol of 9/1 to 2/8 [where (A) and (B) are the respective solid weights], and the surface tension after adjustment is 45 dynes/cm or more. . Both are intended to sufficiently express the desired effect and maintain the effect for a long period of time. Preferably, when (A)/(B)=9/1 to 5/5, D is an organic anionic compound having only one anionic group in the molecule (denoted by d), and The weight ratio is 20-x/500x≦d/(A)+(B)≦20-x/2x [however, x is the average value of the total number of carbon atoms in the hydrocarbon groups in d, and 1≦x<20 ], the weight ratio of E satisfies 1/100≦E/(A)+(B)≦50/100, each of the above cases is preferable. In both cases, (A) and (B) are the respective solid weights, but within the above ranges the desired effect and its long-term sustainability are best achieved, and the transparency of the coating film is obtained. It is. <Function, etc.> The present invention provides a treatment in which the particles of the mixed inorganic colloidal sol of A and B are partially neutralized with D and E and are partially hydrophobized to adjust the surface tension to 45 dynes/cm or more. It has its features. D and E are not required to have a strong wetting effect like the conventional examples. The surface tension of the coating solution is equal to the critical surface tension of the surface of the polymer solid being coated (for example, polyethylene is 31 dynes/
cm, polypropylene is 23 dynes/cm, polystyrene is 33 dynes/cm, polymethyl methacrylate is 39
dynes/cm, polyethylene terephthalate (43 dynes/cm), polyvinyl chloride (40 dynes/cm), and in order to make the solid surface wet, a wetting agent (surfactant) is used. It's completely different. The composition according to the present invention can be appropriately combined with a rust preventive agent or preservative within a range that does not impair the effects of the present invention, and the specific application method is particularly limited, such as spraying, brushing, or gravure coating. Although there is no need to do this after application, drying or heating may be used. In addition, the composition of the present invention can be used not only for molded articles with untreated surfaces, but also for surface treatments such as physical methods such as corona discharge treatment and plasma treatment, and anchor coating agent coating treatment. Needless to say, the present invention can also be applied to molded articles that have been previously modified by the chemical method described above. <Effects of the Invention> As explained above, the present invention provides excellent durability to the surface of molded products made of synthetic resin materials and inorganic materials, easily and without the need for drying or heating after application. This has the effect that it is possible to form a hydrophilic coating film with a certain degree of hydrophilicity. <Examples, etc.> Finally, in order to make the structure and effects of the present invention more concrete, Examples and Comparative Examples are given, but the present invention is not limited to these. - Examples 1 to 14 For each example, A, B and D listed in Table 1, and E (E uses the corresponding raw material compound,
The raw material compounds were mixed with A and B and hydrolyzed at 50°C for 5 hours. A coating liquid having the concentration and surface tension (measured at 25°C using an automatic surface tension meter A-3 manufactured by Kyowa Kagaku Co., Ltd.) as shown in Table 1 was obtained. Then, each coating solution was spray applied onto the inner surface of the base film listed in Table 1, which was set up in a test house with an inclined surface of 15 degrees, with an internal temperature controlled at 30°C and an external temperature controlled at 10°C, and dried, heated, etc. Leave it as it is without doing anything, observe the state of water droplet adhesion on the inner surface,
The water droplet prevention effect of the hydrophilic coating film formed on the inner surface was evaluated based on the following criteria. Results first
Shown in the table. A: Adhesion of water droplets is not observed for 721 days or more after application. B: Adhesion of water droplets is observed 361 to 720 days after application. C: Adhesion of water droplets is observed 181 to 360 days after application. D: Adhesion of water droplets will be observed 91 to 180 days after application E: Adhesion of water droplets will be observed 31 to 90 days after application F: After application , Adhesion of water droplets will be observed in 11 to 30 days G: Adhesion of water droplets will be observed within 10 days after application - Comparative Examples 1 to 8 Each comparative example is listed in Table 2. A coating solution was obtained in the same manner as in the previous example using each of the components. Then, each coating liquid was evaluated in the same manner as in the examples. The results are shown in Table 2.

【table】

【table】

【table】

Claims (1)

[Claims] 1 Using the following A, B and D, (A)/(B) by D
= 9/1 to 2/8 [where (A) and (B) are the respective solid weights] The charges of the particles of the mixed inorganic colloidal sol are partially neutralized and partially hydrophobized to increase the surface tension. A coating composition for surface modification, which is prepared by adjusting the amount of dynes/cm to 45 dynes/cm or more. A: Alumina sol B: Acidic silica sol whose particle surface has a positive charge D: Water-soluble or water-dispersible organic anionic compound 2 D is the following d and the weight ratio is 20-
A patent claim that satisfies x/500x≦d/(A)+(B)≦20−x/2x [where x is the average value of the total number of carbon atoms in the hydrocarbon groups in d and satisfies 1≦x<20] The coating composition for surface modification according to item 1. d: Organic anionic compound 3 having only one anionic group in the molecule Using the following A, B, D and E, (A)/(B) = 9/1 to 2/8 with D and E [ However, (A) and (B) are made by partially neutralizing the electric charge of the mixed inorganic colloidal sol particles of [each solid content weight] and partially making them hydrophobic to adjust the surface tension to 45 dynes/cm or more. A coating composition for surface modification consisting of: A: Alumina sol B: Acidic silica sol whose particle surface has a positive charge D: Water-soluble or water-dispersible organic anionic compound E: Organosilane derivative having 1 to 3 silanol groups in the molecule and/or this organosilane derivative condensate 4 D is the following d and the weight ratio is 20-
A patent claim that satisfies x/500x≦d/(A)+(B)≦20−x/2x [where x is the average value of the total number of carbon atoms in the hydrocarbon groups in d and satisfies 1≦x<20] The coating composition for surface modification according to item 3. 5 The weight ratio of E is 1/100≦E/(A)+(B)≦50/
100. The coating composition for surface modification according to claim 3 or 4, which satisfies 100.