JPS62241984A - Method of surface modification - Google Patents

Abstract

PURPOSE:To easily form a hydrophilic coating having excellent durability on the surface of a hydrophobic material, by applying a particular coating solution on the surface of a hydrophobic material and drying the coating thus formed to allow it to adhere to the material. CONSTITUTION:An org. silane derivative (C) (or a condensate thereof) of formulae I-III (wherein R<1>-R<3> are each an org. group) having 1-3 silanol groups in its molecule is added to a mixed inorg. colloid sol obtd. by mixing an alumina sol (A) with an acidic silica sol (B) contg. positively charged particles having an average particle diameter of 5-100nm in an A to B ratio of 9/1-2/8 in such an amt. as will satisfy the following relationship: 1/100<=C/A+B<=50/100. Thus, a hydrophobic nature is imparted to a part of the particles. A nonionic surfactant (D) is added to the system so as to have a component D concn. of 0.05-2.0wt% and, at the same time, to satisfy the following relationship: A+B+C/D>5. Thus, there is obtd. a coating soln. of which the surface tension was reduced to a value lower than the surface energy of a hydrophobic material. The coating soln. is uniformly applied on the surface of the hydrophobic material, followed by drying to allow the hydrophilic coating to adhere to the material.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a surface modification method for making the surface of a hydrophobic material hydrophilic in continuous processing.

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 that i
Using t 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 crops not be observed from the outside, but the optical transparency of the film or sheet is impeded, resulting in significantly poor crop growth, and depending on the crop, falling water droplets can cause disease. .

Therefore, there is a need for a surface modification method that coats the surface of the molded article to modify the physical properties of the surface and prevent the adhesion of water droplets.

The present invention relates to such a surface modification method, and particularly to a surface modification method that can easily form a highly durable hydrophilic coating on the surface of the molded product during continuous processing.

<Prior art and its problems> Conventionally, as the surface modification method, examples include using a water-soluble polymer, examples using a homopolymer of a vinyl monomer having a hydrophilic polar atomic group in the molecule, and overall There are also examples of using copolymers obtained by copolymerizing other monomers to the extent that they can impart hydrophilicity. 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. However, these conventional examples are generally inferior in the degree of expression of their intended effects compared to examples using water-dispersible sols as described below.

Conventionally, as the surface modification method using a water-dispersible sol,
Examples include the use of water-dispersible sols of inorganic oxides such as alumina and silica. Specifically, examples of using a water-dispersible alumina sol include examples of using the alumina sol together with an anionic or nonionic surfactant (Japanese Patent Publication No. 1983-
32668), an example in which a water-dispersible silica sol and a nonionic surfactant are used in combination (JP-A-6O-96682), and an example in which a water-dispersible silica sol is used in combination with the silica sol, 5, cation and An example of using a nonionic surfactant in combination (Japanese Patent Publication No. 50-11348), an example of using an anionic and nonionic surfactant in combination (Japanese Patent Publication No. 55-5
6177), an example in which a surfactant and a polymer are used in combination (JP-A-51-6193), an example in which a surfactant and a silane derivative are used in combination (JP-A-57-98578), and an example in which the surface of the silica sol is coated with aluminum ions. There is an example in which a surfactant is used in combination with the treatment (Japanese Patent Laid-Open No. 54-20979).

However, according to additional experiments conducted by the present inventors, if the above-mentioned conventional example using a water-dispersible sol is applied in-line or offline when producing a film or sheet, it is difficult to use a surfactant with good surface activity. Conventional examples used as wetting agents have excellent high-speed coating properties, but the long-term sustainability of the effect is poor, and conventional examples that do not use wetting agents have the problem of insufficient high-speed coating properties. Furthermore, coated films and sheets pass through various routes before being applied to, for example, agricultural greenhouses, and many conventional methods have the problem that the coating film tends to fall off due to various frictions and other factors that they are subjected to before installation. Ta.

<Problems to be Solved by the Invention and Means for Solving the Problems> The present invention solves the conventional problems such as ridges, and has excellent high-speed coating properties and long-lasting effects in continuous processing, and is less likely to be damaged by friction. The present invention provides a surface modification method for forming a strong coating film on a surface with a hard surface.

However, as a result of intensive research from the above point of view, the present inventors found that the previously proposed method of using a surfactant in combination with silica sol or alumina sol has similar high-speed coating properties and effectiveness even when silane derivatives are used in combination with these. While it is difficult to achieve both long-term sustainability, when a specific compound selected from these four ingredients is used in a specific formulation system, it has excellent high-speed application and long-term sustainability, and is effective against friction, etc. On the other hand, they discovered that a strong coating film can be formed on a hydrophobic surface, leading to the completion of the present invention.

That is, the present invention uses the following A%B, C, and D in a continuous process in which a coating liquid is uniformly applied to the surface of a hydrophobic material to modify the surface, and υ(A)/(B )
= 9/1 to 2/8 mixed inorganic colloid sol particles that have been partially hydrophobized are added in an amount such that the degree is 0.05 to 2.0% by weight, and the surface tension is adjusted to the surface of the hydrophobic material. The present invention relates to a surface modification method characterized by preparing a coating liquid whose energy is lower than that, uniformly applying the coating liquid to the surface of a hydrophobic material, and then drying and fixing the coating liquid.

A: Alumina sol B: Acidic silica sol whose particle surface has a positive charge C: An organic silane derivative having 1 to 3 silanol groups in the molecule and/or its feedstock D: Nonionic surfactant [However, (A), (B), (C) and (D) are respective solid weights] The alumina sol A is so-called colloidal alumina, and those commercially available as aqueous dispersions can be used as they are. To give such a specific example, alumina sol 10
0, alumina sol 200, alumina sol 520 (and above,
Manufactured by Nissan Chemical Co., Ltd. (all product names), Cataloid AS-1
, Cataloid AS-2 (both are trade names, manufactured by Catalysts & Chemicals Co., Ltd.), and the like.

In addition, the acidic silica sol B mentioned above has an average particle size of 5 to 100.
nm is preferable, and those commercially available as aqueous dispersions can be used as they are.

Specific examples include Snowtex AK (manufactured by Nissan Chemical Co., Ltd., trade name).

The organic silane derivative of C has the following general formula (1),
(1) or (III).

(1) (If) (I) [However, R1, R2, and R3 are organic groups] The above-mentioned organic silane derivatives and condensates thereof are usually the corresponding silyl halides, alkoxysilyl 2: y or r-alkoxyalkoxy 2 It can be obtained by hydrolyzing a raw material compound such as chlorine in the presence of an appropriate inorganic acid, organic acid, or alkaline agent or using only water, but the present invention does not limit the production method. Specific examples of such raw material compounds include methyltrimethoxysilane, methyltriethoxysilane, vinyltrichlorosilane, and vinyltriethoxysilane, which correspond to the organic silane derivative represented by the general formula (1) and the condensate of , vinyltri(methoxyethoxy)silane, vinyltriacetoxysilane, r-chloroprobyltrigloboxysilane, γ
-Mercaptoglobiltriethoxysilane, r-glycidoxyglobiltrimethoxysilane, r-methacryloxyglobiltriethoxysilane, phenyltrimethoxysilane, etc., as well as organic silane derivatives represented by the general formula (I), etc. Examples of condensates thereof include dimethyldimethoxysilane, γ-chloropropylmethyldimethoxysilane, r-glycidoxypropylmethyldimethoxysilane, etc., as well as organic silane derivatives represented by the general formula and their condensates. Examples of corresponding substances include trimethylchlorosilane and trimethylmethoxysilane. Any of these raw material compounds may be used alone or in a mixture of two or more.

The present invention uses the above three components A, B and C in combination, but it may be adjusted by adding C to a mixture of A and B, or by adding C to A and then adding B. In these cases, KC may be brought into contact with A or B to react.

In the present invention, the adjustment target by C is (A) / (B)
It is a mixed inorganic colloidal sol of =9/l to 2/8 [where (A) and (B) are the respective solid weights].

This is to fully express the desired effect and maintain the effect for a long period of time. And preferably, the weight ratio of C is 1/100≦C/(A) + (B)≦50/100
It is better if (A) and (B) are the respective solid weights, and within this range, the desired effect and its long-term sustainability are best exhibited, and the transparency of the coating film can be obtained.

The present invention uses a coating liquid in which the above A, B, and C are blended with the above D in a predetermined ratio and concentration. , aliphatic alcohols such as intritecyl alcohol, substituted phenols such as nonylphenol and dodecylphenol, fatty acids such as lauric acid, valmitic acid, stearic acid, and oleic acid, sorbitan triolate,
There are polyhydric alcohol partial esters such as sorbitan monostearate, sorbitan triolate, glycerin monostearate, and diglycerin diolate, and their ethylene oxide and propylene oxide adducts. Among these, those having an HLB of 8 to 15 are preferred because the amount used can be reduced the most.

The relative amount of D and its concentration in the coating solution are important, and D is (A) + (B) + (C)
7(D) > 5 and the concentration of (D) is 0.05 to 2.
Within these ranges, the surface tension of the coating liquid is adjusted to be equal to or lower than the surface energy of the hydrophobic material to be coated. If these conditions are not met,
Either the high-speed coating properties during continuous processing were not sufficiently achieved, or the long-term sustainability of the effect was insufficient.

When applying the coating liquid during continuous processing, the application means is not particularly limited and can be selected as appropriate, such as spraying, brushing, gravure coating, etc., but it is important to dry it once after application. Only through this drying can the desired effect be obtained.

Prior to applying the method of the present invention, it may be effective in some cases to previously treat the surface of the hydrophobic material with physical treatment such as corona treatment or plasma treatment, or chemical treatment using an anchor coating agent. Additionally, rust preventives, preservatives, and the like may be added to the coating liquid within a range that does not impair the effects of the present invention.

<Effects of the Invention> As explained above, the present invention has the effect of forming a durable and excellent hydrophilic coating film on the surface of a hydrophobic material by high-speed coating during continuous processing. be.

<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 9 35"/m extruder (using a blown film manufacturing device, with a coating liquid immersion bath before winding and a drying zone immediately thereafter), the coating liquids listed in Table 1 were prepared. Test of LDPE coated with LDPE) Two films were produced at a winding speed of 40 m7.The coatability at this time was evaluated using the criteria described below.

Next, each test film was stretched on a test tube having an inclined surface of 15 degrees with an internal temperature of 30°C and an external temperature of 10°C.
The state of water droplet adhesion was observed, and the sustainability of the water droplet prevention effect was evaluated using the criteria described below. Separately, for each test film,
The scratch resistance of the coating film was evaluated using the simple method described below. Results first
Shown in the table.

Incidentally, the coating composition consisting of A+B+C listed in Table 1 was prepared by using the corresponding raw material compound as C, mixing the raw material compound with A and B, and hydrolyzing the mixture for 50'CX5 hours. Comparative Examples 1 to 15 The coating liquids listed in Table 2 were used and evaluated in the same manner as in the Examples. The results are shown in Table 2. 0.Evaluation of applicability...Evaluation was made based on the following criteria.

Good: The coating was applied evenly without causing any repellency.

Poor: Partial repellency phenomenon is observed.

Impossible: Repellency phenomenon is seen throughout.

...Evaluation of sustainability of water droplet prevention effect...Evaluation was made based on the following criteria.

5: Adhesion of water droplets is not observed for 181 days or more after application 4: Adhesion of water droplets is observed 91 to 180 days after application 3: Adhesion of water droplets is observed 31 to 90 days after application 2: Water droplets will be visible within 11 to 30 days after application. 1: Water droplets will be visible within 10 days after application. Scratch resistance. Evaluation of properties: Vinyl tape was pasted on the friction surface of the arm of a friction tester (Gakushin type color fastness tester, manufactured by Mahayana Kagaku Seiki Seisakusho Co., Ltd.), a load of 300 f was applied, and each test film surface was After rubbing 10 times, steam was applied to the friction area, and the degree of peeling of the coating film was observed with the naked eye based on cloudy areas caused by water droplets adhering to the area, and evaluated using the following criteria.

○: Almost no peeling Δ: Slight peeling ×: Almost no peeling Note) Through Tables 1 and 2, (A), (B), (C), ( D) excludes each solvent Ratio is weight ratio, concentration is weight% *1 is total weight% of (A) + (B) + (C) *2
is the total weight% of alumina sol + silica sol + each other excluding the solvent *3 is the equivalent mixture of D-5 and E-1 *4 is the equivalent mixture of D-1 and F-1 in Table 2 , the surfactant of the coating composition is one that is incorporated into the composition before preparing the coating liquid;
In addition, the surfactant in the coating liquid was added at the stage of preparing the coating liquid. Comparative Example 19 was used for evaluation without drying after application. The surface tension of each coating liquid was 41 dynes/lys in Comparative Example 16, All others are less than 30 dynes/1 (LD
The surface energy of PE is 31 dynes/A-1; Alumina Sol 200 (Nissan Chemical Co., Ltd. M) A-2; Cataloid As-
1 (manufactured by Catalysts Kasei Co., Ltd.) A-3; Alumina Sol 520 (manufactured by Nichiryo Kagaku Co., Ltd.) B-1; Snowtex AK (manufactured by Nichiryo Kagaku Co., Ltd., an acidic silica sol whose particle surface has a positive charge) B-2 Nisnotex 40 (manufactured by Nichiryo Kagaku Co., Ltd.) B-3 Nildox AM (manufactured by DuPont, basic silica sol with a negative charge on the particle surface) B-4; Cataloid 5I-350 (Catalyst Kasei Co., Ltd.) B-5: Snowtex BK (manufactured by Nichikagaku Co., Ltd., basic silica sol whose particle surface has a positive charge) B-6: Cataloid SN (manufactured by Catalyst Kasei Co., Ltd., basic silica sol whose particle surface has a positive charge) Acidic silica sol whose particle surface has a negative charge) Layer C-2: &NCNHCaHaSi (OC2H5)3
C-3: (CHa)2Si (OCH3)2C-4:
CHaSi (OC2H5)3D-1: POE lauryl ether (HLBlo, 5, POE is polyoxyethylene, the same applies hereinafter) D-2: POE nonylphenyl ether (HL812.
4) D-3; POE olein woven ester (HLBlo, 4) D-4; POE (20 mol) sorbitan monostearate) (HLB 14.9) D-5: POE lauryl ether (HLB 16.9) D-6: POE (20 mol) rubitan monolaure)
(HLB16.7) D-7: Metrose 5M-15 (manufactured by Shin-Etsu Chemical Co., Ltd.) E-1: Lauryltrimethylammonylammonylolide F-1 Sodium Nidodecylbenzenesulfonate F-2: Cer70-8113 (Asahi Glass Co., Ltd.) M) The superior effects of the present invention are clear from the results in Table 1 relative to Table 2.

Claims (1)

[Claims] 1. In continuous processing of uniformly applying a coating liquid to the surface of a hydrophobic material to modify the surface, the following A, B, C
Using and D, (A)/(B) = 9/1 to 2/ by C
The particles of the mixed inorganic colloid sol of No. 8 were partially hydrophobized, and D was (A) + (B) + (C) / (D) > 5 and the concentration of (D) was 0.05 to 2. A coating liquid is prepared by adding an amount of 0% by weight and the surface tension is lower than the surface energy of the hydrophobic material, and the coating liquid is uniformly applied to the surface of the hydrophobic material, and then dried and fixed. surface modification method. A: Alumina sol B: Acidic silica sol whose particle surface has a positive charge C: Organosilane derivative and/or its condensate having 1 to 3 silanol groups in the molecule D: Nonionic surfactant [However, (A), (B), (C) and (D) are the respective solid weights] 2C is 1/100≦(C)/(A)+(B)≦50
The surface modification method according to claim 1, which satisfies the condition: /100.