JPH07116423B2 - Surface modification method - Google Patents

Description

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

Molded parts made of synthetic resin materials such as polyethylene, polyvinyl chloride, polyester, polymethylmethacrylate and inorganic materials such as glass are generally hydrophobic and have a low affinity for water. When used, it can cause various problems. For example, when a film or sheet made of the synthetic resin material is used for a cover of an agricultural house, water vapor evaporating from soil or crops agglomerates on their surfaces to form a large number of water droplets. As a result, not only the crop cannot be observed from the outside, but also the light transmission of the film or sheet is disturbed, the growth of the crop is significantly deteriorated, and some crops cause a disease due to falling water droplets.

Therefore, as one means, there is a demand for the appearance of a surface modification method in which a coating liquid is applied to the surface of a hydrophobic material such as the above-mentioned molded article to modify the physical properties of the surface and prevent the adhesion of water droplets. To be done.

The present invention relates to such a surface modification method, and more particularly to a surface modification method capable of easily forming a hydrophilic coating having excellent durability on the surface of a hydrophobic material in continuous processing.

<Conventional technology and its problems> Conventionally, as a method for modifying the surface of a hydrophobic material, an example of coating a water-soluble polymer on the surface, a homopolymer of a vinyl monomer having a hydrophilic polar atomic group in the molecule There is an example of applying the above, an example of applying a copolymer in which other monomers are copolymerized to the extent that hydrophilicity can be imparted as a whole. These are applied to the surface of a hydrophobic material with an aqueous or organic solvent system, and subsequently cured or insolubilized by various methods as needed. However, these conventional examples are generally inferior in the degree of manifestation of the intended effect as compared with the examples of applying the water-dispersible sol as described below.

As a method for modifying the surface of a hydrophobic material by applying a water-dispersible sol, an example in which a water-dispersible sol of an inorganic oxide such as alumina or silica is applied to the surface has been conventionally proposed. Specifically, as an example of applying the water-dispersible alumina sol, an example of applying the anion or nonionic surfactant in combination with the alumina sol (Japanese Patent Publication No. 49-32668), water-dispersible silica sol and nonionic surfactant There is an example of applying a combination of agents (JP-A-60-96682), and as an example of applying a water-dispersible silica sol, both are applied with a combination of a cation and a nonionic surfactant on the silica sol. Example (Japanese Patent Publication No. 50-11348), Example of applying anionic and nonionic surfactants in combination (JP-A-55-56177), Example of applying surfactants and polymers in combination (JP-A-51-619)
3), an example of applying a surfactant and a silane derivative together (JP-A-57-98578), and further an example of treating the surface of the silica sol with aluminum ions and applying a surfactant together with it. (Japanese Patent Laid-Open No. 54-20979).

However, according to the additional test by the present inventors, when the conventional examples using the water-dispersible sol as described above are applied by in-line or off-line continuous processing when producing a film or sheet, good surface activity is obtained. The conventional examples using a surfactant as a wetting agent have excellent high-speed coating properties, but the long-term effect is inferior, and the conventional examples not using a wetting agent have a problem that the high-speed coating properties are insufficient. Further, the applied film or sheet goes through various routes until it is applied to, for example, an agricultural house, but many conventional examples also have a problem that the coating film is likely to fall off due to various frictions received before the installation. .

<Problems to be Solved by the Invention, Means for Solving the Problems> The present invention solves the above-mentioned conventional problems, is excellent in high-speed coating property and long-term effect in continuous processing, and is less damaged by friction. It is intended to provide a surface modification method capable of forming a robust coating film on the surface of a hydrophobic material.

However, as a result of earnest research from the above viewpoints, the inventors of the present invention have proposed a method of applying a surfactant together with a silica sol or an alumina sol, which has been conventionally proposed, and also apply a silane derivative in addition thereto. Similarly, it is difficult to achieve both high-speed coating property and long-term sustainability of the effect. On the other hand, if a specific one selected from these four components is used in combination at a specific ratio, high-speed coating property and It has been found that a coating film that is excellent in long-term sustainability of the effect and that is robust against friction and the like can be formed on the surface of the hydrophobic material.

That is, the present invention uses the following A, B, C and D in the continuous processing for uniformly applying the coating liquid to the surface of the hydrophobic material and modifying the surface, and (A) / (B) depending on C.
= 9/1 to 2/8 mixed inorganic colloid sol particles partially hydrophobized, and D is {(A) + (B) + (C)} /
(D)> 5 and the concentration of (D) is added in an amount of 0.05 to 2.0% by weight to prepare a coating liquid whose surface tension is equal to or less than the surface energy of the hydrophobic material. The present invention relates to a surface modification method, which comprises uniformly coating the surface of the above, followed by drying and fixing.

A: Alumina sol B: Acidic silica sol whose particle surface has a positive charge C: Organosilane derivative having 1 to 3 silanol groups in the molecule and / or its condensate D: Nonionic surfactant [however, (A), (B), (C), and (D) have the same solid content weight, and the same applies hereinafter.] The alumina sol A is so-called colloidal alumina, and commercially available aqueous dispersions can be used as they are. As such a specific example, alumina sol 10
0, Aluminasol 200, Aluminasol 520 (all manufactured by Nissan Chemical Co., Ltd., all trade names), Cataloid AS-1, Cataloid AS-2 (all manufactured by Catalysts & Chemicals Co., Ltd., all trade names) and the like.

The acidic silica sol of B has an average particle size of 5 to 100 nm.
What is marketed as an aqueous dispersion can also be used as it is. Snowtex AK (manufactured by Nissan Kagaku Co., Ltd.) is a specific example.

The organosilane derivative of C has the following general formula (I):
It is represented by (II) or (III).

[However, R ¹ , R ² and R ³ are organic groups] The above-mentioned organic silane derivative or a condensate thereof is usually prepared by using a corresponding raw material compound such as silyl halide, alkoxysilane or γ-alkoxyalkoxysilane with an appropriate inorganic acid, It can be obtained by hydrolysis in the presence of an organic acid or an alkaline agent or by using only water, but the present invention does not limit the production method thereof. Specific examples of the raw material compounds include methyltrimethoxysilane, methyltriethoxysilane, vinyltrichlorosilane, vinyltriethoxysilane, and vinyltriethoxysilane, which correspond to the organosilane derivative represented by the general formula (I) and a condensate thereof. Vinyltri (methoxyethoxy) silane, vinyltriacetoxysilane, γ-chloropropyltripropoxysilane, γ-
There are mercaptopropyltriethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-methacryloxypropyltriethoxysilane, phenyltrimethoxysilane, etc., and the organic silane derivative represented by the general formula (II) and its condensate Corresponding ones include dimethyldimethoxysilane, γ-chloropropylmethyldimethoxysilane, γ-glycidoxypropylmethyldimethoxysilane, and the like, which further correspond to the organosilane derivative represented by the general formula (III) and its condensates. Examples include trimethylchlorosilane and trimethylmethoxysilane. Any of these starting compounds may be used alone or in a mixture of two or more.

The present invention uses the above three components of A, B and C in a composite manner, but it may be adjusted by adding C to the mixture of A and B, or by adding C to A and then adding B. It may be added, and in these cases, C may be reacted with A or B by contact.

In the present invention, the adjustment target by C is (A) / (B) =
9/1 to 2/8 mixed inorganic colloid sol. This is because the desired effect is sufficiently expressed and the effect is sustained for a long time. And preferably, the weight ratio of C is 1/100 ≦
The case of (C) / {(A) + (B)} ≦ 50/100 is preferable. This is because within this range, the desired effect and its long-term sustainability are best exhibited, and the transparency of the coating film is obtained.

The present invention uses a coating liquid prepared by mixing the above A, B and C with the above D at a predetermined ratio and at a predetermined concentration. Examples of the D include 1) octyl alcohol,
Ethylene oxide and propylene oxide adducts of aliphatic alcohols such as cetyl alcohol, stearyl alcohol, oleyl alcohol and isotridecyl alcohol, 2) Ethylene oxide and propylene oxide adducts of substituted phenols such as nonylphenol and dodecylphenol, 3) Ethylene oxide and propylene oxide adducts of fatty acids such as lauric acid, palmitic acid, stearic acid and oleic acid, 4) sorbitan trilaurate, sorbitan monostearate, sorbitan trioleate, glycerin monostearate, diglycerin dioleate, etc. There are ethylene oxide and propylene oxide adducts of polyhydric alcohol partial esters. Among them, those having HLB 8 to 15 are preferable because the use amount thereof can be reduced most.

The relative amount of D and its concentration in the coating liquid are important, and D is {(A) + (B) + (C)} /
(D)> 5 and the concentration of (D) is set to 0.05 to 2.0% by weight, and 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 applied in these ranges. If these conditions are not satisfied, the high-speed coating property during continuous processing may not be sufficiently obtained, or the long-term sustainability of the effect may be insufficient.

When applying the coating liquid in continuous processing, the application means is not particularly limited and may be spray, brush coating, gravure coating, or the like, and can be appropriately selected, but it is important to dry once after coating. The desired effect can be obtained only by the drying.

Prior to applying the method of the present invention, it is also effective in some cases to pretreat the surface of the hydrophobic material by physical treatment such as corona treatment or plasma treatment or chemical treatment using an anchor coating agent, Further, an anticorrosive agent, an antiseptic agent and the like can be added to the coating liquid within a range that does not impair the effects of the present invention.

<Effects of the Invention> As described above, the present invention has the effect that a durable and excellent hydrophilic coating film can be formed by high-speed coating on the surface of a hydrophobic material in continuous processing. is there.

<Examples> Hereinafter, in order to make the configuration and effects of the present invention more specific,
Examples and comparative examples will be given, but the present invention is not limited to these examples.

Examples 1 to 9 35 m / m extruder-LDPE coated with the coating liquid shown in Table 1 using a blown film manufacturing apparatus, provided with a coating liquid dipping bath before winding and a drying zone immediately after that. Test film was prepared at a winding speed of 40 m / min. Then, the coating property at this time was evaluated according to the below-mentioned criteria.
Next, each test film was attached to a test house having an inclined surface of 15 degrees adjusted to an internal temperature of 30 ° C and an external temperature of 10 ° C, and the state of water droplet adhesion was observed, and the persistence of the water droplet prevention effect was determined according to the criteria described below. evaluated. Separately, each test film was evaluated for scratch resistance of the coating film by the simple method described below. The results are shown in Table 1.

Incidentally, in A, B and C used in the examples, corresponding raw material compounds were used as C, and the raw material compounds were previously mixed with A and B and hydrolyzed at 50 ° C. for 5 hours.

-Comparative Examples 1 to 14 The coating liquids shown in Table 2 were used and evaluated in the same manner as in Examples. The results are shown in Table 2.

.. Evaluation of coating property ... The following criteria were evaluated.

Good: Coated uniformly without causing cissing.

Poor: Repelling phenomenon is partially observed.

Impossible: Repelling phenomenon is seen on the whole.

..Evaluation of sustainability of water drop prevention effect ... The following criteria were used for evaluation.

5: No adhesion of water droplets is observed for 181 days or more after application 4: Adhesion of water droplets can be observed 91 to 180 days after application 3: Adhesion of water droplets 31 to 90 days after application 2: Adhesion of water droplets can be observed within 11 to 30 days after application 1: Adhesion of water droplets can be observed within 10 days of application ・ Scratch resistance Evaluation ... A vinyl tape was attached to the friction surface of the arm of a friction tester (Gakshin type dyeing fastness tester, manufactured by Daiei Kagaku Seiki Seisakusho Co., Ltd.), a load of 300 g was applied, and each test film surface was rubbed 10 reciprocations. After that, steam was applied to the rubbed portion, and the degree of peeling of the coating film was visually observed by the clouded portion caused by the adhesion of water droplets, and the following criteria were used for evaluation.

◯: Almost no peeling was observed Δ: Some peeling was observed ×: Almost peeled Note) Through Tables 1 and 2, (A), (B), (silica sol), (C), and (D) are obtained by excluding the respective solvents. Ratio is weight ratio, concentration is weight% * 1 Total weight% of (A) + (B) + (C) * 2 is of {(A) + (B) + (C)} / (D) * 3 is of (A) + (silica sol) + (C) Total weight% * 4 is {(A) + (silica sol) + (C)} / surfactant Comparative Example 13 is an example which is not dried yet after coating and evaluated for surface tension. Dyne / cm, all others 30 dyne / cm or less (LDPE surface energy is 31 dyne / cm) A-1: Alumina sol 200 (Nissan Chemical Co., Ltd.) A-2: Cataloid AS-1 (Catalyst Kasei Co., Ltd.) A -3: Alumina sol 520 (manufactured by Nissan Chemical Co., Ltd.) B-1: Snowtex AK (manufactured by Nissan Chemical Co., acidic silica sol with positively charged particle surface) B-2: Snowtex B K (manufactured by Nissan Chemical Co., Ltd., basic silica sol with positively charged particle surface) B-3: Cataloid SN (manufactured by Catalysts & Chemicals, acidic silica sol with negatively charged particle surface) _{C-3: (CH 3)} 2 Si (OCH 3) 2 C-4: CH 3 Si (OC 2 H 5) 3 D-1: POE lauryl ether (HLB 10.5, POE is polyoxyethylene, hereinafter the same) D-2: POE nonyl phenyl ether (HLB12.4) D-3: POE oleic acid ester (HLB10.4) D-4: POE (20 mol) sorbitan monostearate (HLB
14.9) E-1: Lauryltrimethylammonium chloride F-1: Sodium dodecylbenzene sulfonate The excellent effect of the present invention is also clear from the results of Table 1 against Table 2.

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Claims (2)

[Claims] 1. In continuous processing for uniformly coating a surface of a hydrophobic material with a coating liquid to modify the surface, the following A, B, C and D are used, and C is (A) / (B) = 9 /
Partially hydrophobized particles of the mixed inorganic colloid sol of 1 to 2/8, D is {(A) + (B) + (C)} / (D)
> 5 and (D) is added in an amount of 0.05 to 2.0% by weight to prepare a coating liquid having a surface tension not higher than the surface energy of the hydrophobic material, and the coating liquid is applied to the surface of the hydrophobic material. A surface modification method, which comprises uniformly coating and then drying and fixing. A: Alumina sol B: Acidic silica sol whose particle surface has a positive charge C: Organosilane derivative having 1 to 3 silanol groups in the molecule and / or its condensate D: Nonionic surfactant [however, (A), (B), (C) and (D) are the weight of each solid content] 2. C is 1/100 ≦ (C) / {(A) +
The surface modification method according to claim 1, wherein (B)} ≦ 50/100 is satisfied.