JP2019203127A - Curable resin composition excellent in water repellency - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a coating agent capable of obtaining a coating film excellent in water repellency, abrasion resistance, deep glossiness, slipperiness of coating film surface and durability. A water-repellent coating agent comprising the following components (1) to (4), which is applied to a substrate and then cured by natural drying at room temperature. Then, a coating film having excellent durability is obtained. (1) A dimethyl silicone polymer having a silanol group at both ends and a number average molecular weight (Mn) of 50,000 to 200,000, (2) a trifunctional silane compound and / or a partial hydrolyzed condensate thereof, and (3) bismuth organic carboxylate. A curing agent containing a salt compound, (4) a solvent. [Selection diagram] None

Description

The present invention relates to a coating agent suitable for producing a durable water-repellent coating film having excellent surface slipperiness, a durable water-repellent coating film having excellent surface slipperiness, and a method for producing the coating film. .

Conventionally, by applying water-repellent coating agents made of fluorine-based materials and silicone-based materials that can reduce the surface energy, and these water-repellent coating agents for the purpose of preventing contamination by rainwater etc. on the surfaces of various substrates. Obtained water-repellent coating films have been studied. In particular, in order to improve the durability of the coating film, a method has been used in which a water-repellent coating agent is applied to the surface of various substrates, and then a crosslinking reaction is performed by heat treatment or irradiation with actinic rays such as ultraviolet rays. It was.

As the fluorine-based material, a material containing a fluorinated alkyl group (Rf group) is known. Such a material can impart water repellency by allowing Rf groups to be present only on the surface, but has a problem that it is inferior in durability such as an effect of improving the slipperiness of the coating film surface and wear resistance.

In addition, for the purpose of improving durability, a method for producing a material having a surface excellent in water repellency and wear resistance by being treated with a coating agent comprising an acrylic UV curable resin and a fluorine surface modifier has been proposed. Yes. However, it has a problem that it requires a special processing apparatus and lacks general versatility, such as being difficult to apply to a large-sized substrate or an irregular substrate material, in addition to poor slipperiness of the coating film surface.

On the other hand, a curable material made of a dimethyl silicone compound having silanol groups or acrylic groups at both ends is known as a silicone material. Since these materials have a structure in which not only the surface but also the inside is three-dimensionally cross-linked, they have a feature of having excellent wear resistance. However, the conventional silicone-based material has a problem that special equipment such as a heating device or an ultraviolet irradiation device is required. Furthermore, there is a problem that it is difficult to combine practically important design properties such as water repellency and deep gloss and prevention of contamination by rainwater. Furthermore, since the molecular weight of the silicone-based material is small, there is also a problem that the slipperiness of the coating film surface is inferior.

Also, it has been proposed to obtain a water-repellent surface by forming protrusions made of a water-repellent material on the surface, but there is a problem that the half surface having high water repellency is also inferior in wear resistance and lacks durability. Furthermore, since it also has a drawback of reducing glossiness, it is not preferable for applications in which design properties are particularly important.

Furthermore, a moisture-curing coating agent that cures with the humidity of the outside air without using a special device has also been proposed, but the water repellency and surface slipperiness are insufficient, or the film thickness of the coating film is insufficient. Therefore, there is a problem that it is difficult to obtain a surface that achieves both water repellency and durability.

In addition, since the future use of organotin compounds may be restricted due to the recent trend of environmental regulations, the development of materials that replace organotin compounds is desired.

Japanese Patent Laid-Open No. 62-148902 Japanese Patent Laid-Open No. 11-269287 JP 2006-346900 A JP-A-10-36771 JP 2008-75021 A JP 2014-111709 A

In view of the above-mentioned conventional drawbacks, the present invention is suitable for the production of a water-repellent coating film excellent in durability, having excellent practicality such as surface slipperiness, in addition to excellent water repellency, and in handling safety. It aims to provide an excellent water-repellent coating agent.

Furthermore, by applying the water-repellent coating agent of the present invention, it is possible to provide a water-repellent coating film excellent in surface slipperiness under mild conditions such as in a natural environment without using a special processing apparatus, and easily Another object of the present invention is to provide a method for producing a coating film having a good appearance.

As a result of intensive studies to solve the above-mentioned problems, the present inventors have found a water-repellent coating agent characterized by containing the following components (1) to (4).
(1) Number average molecular weight (Mn) having silanol groups at both ends is 50,000 to 200,00
0 dimethyl silicone polymer (2) trifunctional silane compound and / or partial hydrolysis condensate thereof (3) curing agent containing organic carboxylic acid bismuth salt compound (4) solvent

In addition, as a method for producing a coating film that solves the above problems, the inventor applied a water-repellent coating agent containing the above components (1) to (4) and used a cloth made of ultrafine long fibers. The present inventors have found a method for producing a water-repellent coating film characterized by spreading.

In the present invention, a dimethyl silicone polymer having silanol groups at both ends and having a number average molecular weight (Mn) of 50,000 to 200,000 has silanol groups represented by Si—OH at both ends, and a commercially available material is used. Is possible.

In order to obtain a coating film having high water repellency, a so-called high water static contact angle, and high surface slipperiness, it is necessary to use a dimethyl silicone polymer having a number average molecular weight (Mn) of 50,000 or more. A dimethylsilicone polymer material having a number average molecular weight (Mn) of less than 50,000 and a small molecular weight cannot provide high water repellency or good coating surface slipperiness. Number average molecular weight (Mn) is 55,000 or more to obtain high water repellency or coating surface slipperiness with a thinner film thickness, and number average molecular weight to obtain higher water repellency and coating surface slipperiness. It is preferable to use a dimethyl silicone polymer having silanol groups at both ends with (Mn) of 60,000 or more.

On the other hand, a dimethyl silicone polymer material having a high number average molecular weight (Mn) is useful for developing a coating surface slipperiness in addition to high water repellency, but as the number average molecular weight (Mn) of the dimethyl silicone polymer increases. The viscosity becomes high, and particularly when it exceeds 200,000, the fluidity is almost lost, so that handling properties such as wiping properties tend to be extremely difficult.

However, with a dimethyl silicone polymer having a number average molecular weight (Mn) of up to 200,000, a uniform coating film can be obtained by improving the coating method. However, if it exceeds 200,000, it is not only difficult to cope with the coating method, but also the production of the material itself is difficult, difficult to obtain, and expensive, so that there is a problem that the practicality is poor.

In order to further improve the compatibility between the material having a high number average molecular weight (Mn) and the component (2) of the present invention, it is also preferably used in combination with a dimethyl silicone polymer having a relatively small number average molecular weight (Mn).

The number average molecular weight (Mn) referred to in the present invention can be easily measured by using a GPC system (Gel Permeation Chromatography System) used for measuring the molecular weight of ordinary synthetic polymers. For example, a method using a high-speed GPC apparatus (HLC-8220GPC) manufactured by Tosoh Corporation and using chloroform as a developing solvent can be mentioned.

The number average molecular weight (Mn) effective for improving the compatibility described above for the purpose of improving the ease of use of the water-repellent coating agent of the present invention, controlling the curing rate, improving stickiness, and improving the antifouling property to oil and fat components, etc. ) Is less than 50,000, it is possible to use a dimethyl silicone polymer having silanol groups at both ends.

Furthermore, for the purpose of controlling the refractive index of the coating film, a silicone polymer having silanol groups at both ends containing a phenyl group or a trifluoropropyl group can be used in combination.

Although the water-repellent coating agent of the present invention is hardly said to have excellent wettability to the substrate, since the water-repellent coating agent of the present invention is applied to an extremely thin film thickness, it can be uniformly applied and durable with a strong affinity with the substrate. It is possible to ensure safety.

In order to improve the wettability with the substrate and improve the coating properties, it is necessary to use a dimethyl silicone polymer having silanol groups at both ends having a number average molecular weight (Mn) of less than 50,000 to lower the coating performance. It is preferable because it is possible without any problems.

Addition amount of dimethyl silicone polymer having silanol groups at both ends and a number average molecular weight (Mn) of less than 50,000, phenyl group-containing silicone polymer, trifluoropropyl group-containing silicone polymer, etc. decreases water repellency. Since it tends to reduce the slipperiness of the coating film surface, it should be determined in relation to the target properties.

Materials that can be obtained as dimethyl silicone polymers having silanol groups at both ends having a number average molecular weight (Mn) of 50,000 to 200,000 as component (1) of the present invention include DMS-S42, DMS-S45, DMS-S51 (GELEST Inc.).

These dimethyl silicone polymers having silanol groups at both ends can be used alone or in combination of two or more.

Examples of materials that can be used in combination with the above component (1) of the present invention as dimethyl silicone polymers having silanol groups at both ends having a number average molecular weight (Mn) of less than 50,000 include PRX413, BY16-873 (Toray Dow Corning), X-21-5841, KF-9701 (Shin-Etsu Silicone), DMS-S12, DMS-S14, DMS-S15, DMS-S21, DMS-S27, DMS-S31, DMS-S32, DMS-S33 And DMS-S35 (manufactured by GELEST Inc.).

PDS-0338 and PDS-1615 (manufactured by GELEST Inc.) as phenyl group-containing silicone polymers having silanol groups at both ends, and FMS-9921 and FMS-9922 (GELEST Inc. as trifluoropropyl group-containing silicone polymers). Manufactured).

Next, component (2) will be described below. The component (1) contained in the water-repellent coating agent of the present invention is liquid or fluid by itself, but is a highly viscous liquid, has poor water repellency in an uncured state, and has a large stickiness. Therefore, a practical coating film cannot be obtained.

Therefore, in order to obtain a coating film containing the component (1) having excellent water repellency and slipperiness, it is necessary to perform three-dimensional crosslinking. The component used for that purpose is component (2).

That is, by using the component (2), the coating film has a three-dimensional cross-linking structure, has water repellency, durability such as abrasion resistance, weather resistance, etc., and imparts slipperiness of the coating surface. Is possible.

Here, the content of the component (2) of the present invention is sufficient as long as the component (1) is three-dimensionally cross-linked so that it can contain stickiness and durability, but it is usually a feature of the present invention. In order to allow curing at room temperature, it is desirable to use 5 to 1,000 parts by weight of component (2) with respect to 100 parts by weight of component (1). Furthermore, in order to satisfy both performance of water repellency and slipperiness, it is preferable to use 10 parts by weight to 900 parts by weight of component (2) with respect to 100 parts by weight of component (1).

In addition, the weight part in the component (2) indicates the number of parts defined as the weight when the amount of the residual compound after the compound used is cured by moisture or the like becomes constant. Incidentally, since the component (1) has substantially no volatility, the used weight itself becomes part by weight. Therefore, the weight part of the component (2) can be obtained as a weight part obtained by subtracting the component (1) from the total weight part after curing.

Component (2) is a trifunctional silane compound and / or a partially hydrolyzed condensate thereof, and is a dimethyl silicone having a number average molecular weight (Mn) of 50,000 to 200,000 having silanol groups at both ends as component (1) It is not particularly limited as long as it is a material that can cure the polymer without requiring a special device, but from the viewpoint of curing speed, stability of the cured film, and further imparting durability of water repellency and slipperiness of the cured film. The following materials are preferably used.

Here, as a trifunctional silane compound, the silane compound represented by the following general formula (A) is mentioned.
R ¹ Si (OR ² ) ₃ (A)
(Here, R ¹ is an alkyl group having 1 to 3 carbon atoms or an alkenyl group, and OR ² is a hydrolyzable group).

Examples of the alkyl group having 1 to 3 carbon atoms include a methyl group, an ethyl group, a propyl group, and an isopropyl group. Among them, examples of the alkyl group having an excellent balance between water repellency and curability include a methyl group and an ethyl group. Furthermore, examples of the alkyl group that can further enhance the durability include a methyl group.

Examples of the alkenyl group include a vinyl group and an allyl group. Among them, a vinyl group is preferably used because of its high stability to heat and moisture and easy availability.

Next, OR ² which is a hydrolyzable group will be described. OR ² is not particularly limited as long as it is a functional group that can be hydrolyzed, but it is easy to hydrolyze, that is, the viewpoint that the hydrolysis reaction can proceed easily by moisture in the air. Therefore, an acyloxy group and a lower alkoxy group are preferably used, and two or more mixed groups may be used.

Among these, considering the curing treatment by standing in a room temperature environment, an acyloxy group having 1 to 8 carbon atoms and an alkoxy group are excellent in terms of hydrolyzability and volatility after hydrolysis. Among them, particularly preferred hydrolyzable groups include at least a part of the hydrolyzable groups as preferred hydrolyzable groups such as an acetoxy group, a methoxy group, and an ethoxy group. Furthermore, considering that it is desired that the coating agent of the present invention can be applied even in an environment that does not have special ventilation facilities, a methoxy group and an ethoxy group are preferable from the viewpoint of odor and irritation after volatilization. Of these, a methoxy group is most preferred because it has moderate hydrolyzability, excellent volatility and little odor. In the case of two or more mixed groups, at least one is preferably a methoxy group or an ethoxy group.

As a partial hydrolysis-condensation product of a trifunctional silane compound, a compound obtained by hydrolyzing the silane compound represented by the general formula (A) with water that does not gel and then condensing the hydrolyzate by aging In addition, there is a compound in which condensation is further advanced by concentrating.

Here, the silane compound represented by the general formula (A) is a trifunctional silane compound, and further, the hydrolyzate is not allowed to gel to enable solution coating, and the partially hydrolyzed condensate In view of the effect of the hydrolysis, the amount of water used for hydrolysis is 1.20 mol to 0.04 mol per 1 mol of the trifunctional silane compound, and 1.10 mol in order to proceed with condensation while suppressing gelation. It is desirable that the amount be ˜0.08 mol, more preferably 1.05 mol to 0.16 mol. That is, when the amount is less than 0.04 mol, the remaining amount of the unreacted trifunctional silane compound is increased, and the effect of forming a partially hydrolyzed condensate is reduced.

In the case of a trifunctional silane compound in which a hydrolyzable group has a methoxy group or an ethoxy group and the R ¹ functional group has a lower alkyl group and easily undergoes a crosslinking reaction, 1.10 mol to 0.40 mol. More preferably, 1.05 mol to 0.50 mol is most preferable.

In the hydrolysis, in order to make the hydrolysis reaction proceed smoothly and more reliably, it is also useful means to add an acid or a base to the water to be used, or to warm it. In particular, when dealcoholization or decarboxylation is performed after hydrolysis, dilute hydrochloric acid is preferred as the acid used for hydrolysis in order not to leave an acid or base in the partially hydrolyzed condensate after concentration. The concentration of dilute hydrochloric acid varies depending on the type of hydrolysis functional group and the type of R ¹ functional group, but usually 0.005N to 1.500N hydrochloric acid is used.

Since the trifunctional silane compound represented by the general formula (A) is usually poor in compatibility with water, it becomes a heterogeneous reaction until the hydrolysis reaction partially proceeds. Addition of a ketone compound such as alcohol or acetone to the trifunctional silane compound for the purpose of making the reaction uniform is also preferably applied. The alcohol added at that time is preferably the same or lower alcohol than the alcohol formed after hydrolysis.

The hydrolysis reaction is usually carried out by adding water to the trifunctional silane compound, but there is no problem even if the water to be added is added dropwise while stirring, or even if it is added all at once. In addition, since the hydrolysis reaction is a reaction accompanied by heat generation, it is also a preferred embodiment that the external temperature is cooled in order to suppress abnormal volatilization of alcohol generated by hydrolysis.

In addition, dehydration condensation after hydrolysis can proceed sufficiently by aging at room temperature, but in order to proceed with dehydration condensation more reliably, dehydration condensation is more complete by concentrating the hydrolyzate by dealcoholization etc. The reaction can proceed.

The resulting partially hydrolyzed condensate is a condensate having an alkoxy group having substantially no silanol group or an acyloxy group as a substituent based on the result of analysis by GC (gas chromatogram) and the like from the generated alcohol species and the amount produced. It can be confirmed that it is a compound.

Specific analysis conditions for gas chromatogram analysis, which is the simplest and most useful analysis means, will be described below.

A commercially available apparatus can be used as the gas chromatogram apparatus, and a specific apparatus is GC-2010 manufactured by Shimadzu Corporation. Specific analysis conditions are described below.
Column: Shinwa Chemical Co., Ltd. ULBON HR-52 (inner diameter 0.25 mm, length 30 mL, film thickness 0.25 μm),
Carrier gas: helium, flow rate (linear velocity) 30cm / sec.
Spirit ratio for column injection: 30 to 1
Inlet temperature: 200 ° C
Column temperature: 40 ℃ / 5min hold → 10 ℃ increase per minute → 100 ℃
Detection temperature: 200 ℃
Detector: FID

Specific examples of the trifunctional silane compound represented by the general formula (A) in the present invention include methyltriacetoxysilane, ethyltriacetoxysilane, propyltriacetoxysilane, isopropyltriacetoxysilane, and vinyltriacetoxysilane. , Methyltrimethoxysilane, ethyltrimethoxysilane, propyltrimethoxysilane, isopropyltrimethoxysilane, vinyltrimethoxysilane, methyltriethoxysilane, ethyltriethoxysilane, propyltriethoxysilane, isopropyltriethoxysilane, vinyltriethoxysilane , Methyltripropionoxysilane, ethyltripropionoxysilane, propyltripropionoxysilane, isopropyltripropionoxysilane, vinyltripropion Noxysilane, methyltripropoxysilane, ethyltripropoxysilane, propyltripropoxysilane, isopropyltripropoxysilane, vinyltripropoxysilane, methyltributoxysilane, ethyltributoxysilane, propyltributoxysilane, isopropyltributoxysilane, vinyltributoxy Silane etc. are mentioned.

These trifunctional silane compounds can be added and mixed in the composition as they are. However, in general, many trifunctional silane compounds have volatility, and some of them are volatilized at the coating stage, and the volatilization amount greatly depends on the environment such as temperature and humidity. Since it becomes a variation factor, it is preferable to hydrolyze it beforehand and use it as a partial hydrolysis condensate. Moreover, since the partial hydrolysis-condensation product increases the number of hydrolysis functional groups in one molecule, it has the effect of increasing the degree of crosslinking, and as a result, it is also effective in improving the durability of the coating film.

Trifunctional silane compounds can be used alone, but for the purpose of improving the balance between durability, curing speed and water repellency, two or more trifunctional silane compounds including partial hydrolysis condensates are included. Needless to say, it can be used in combination.

In particular, the water repellency and slipperiness are satisfied, and the durability of these performances is enhanced. In addition, because the properties are liquid at room temperature, it is easy to handle. Trifunctional silane compounds having an alkoxy group or a lower acyloxy group are preferred. Of these, methyltriacetoxysilane compounds, ethyltrimethoxysilane compounds, methyltriethoxysilane compounds, ethyltriethoxysilane compounds, and acyloxysilane compounds are particularly preferably methyltriacetoxysilane compounds and ethyltriacetoxysilane compounds.

A mixed system of an ethyltriacetoxysilane compound and a methyltriacetoxysilane compound can be handled as a liquid at room temperature, and can further increase the degree of cross-linking, and can be mentioned as one of preferred embodiments. .

Further, partial hydrolysis condensates of trifunctional silane compounds include methyltrimethoxysilane compounds, methyltriethoxysilane compounds, ethyltrimethoxysilane compounds and ethyltriethoxysilane compounds. It is most preferable because it has good wiping properties because of its excellent compatibility with the excellent component (1), good solubility in a solvent, and reactivity after coating.

As long as the trifunctional silane compound is present as an alkoxy group, whether it is an uncondensed monomer or a partially hydrolyzed condensate oligomer partially condensed in the paint, There is no problem.

That is, the OR ² group in the trifunctional silane compound is an alkoxy group in which two-thirds or more are unreacted, preferably one-half or more, and most preferably one-tenth or more are unreacted. The acyloxy group is necessary for wiping and securing a good appearance.

Moreover, as the partial hydrolysis-condensation product of such a trifunctional silane compound, a commercially available product can be used as it is. Specific examples of materials used include KR-400N (manufactured by Shin-Etsu Chemical Co., Ltd.). In addition, KR-400 (manufactured by Shin-Etsu Chemical Co., Ltd.) in which 0.5 wt% to 5 wt% of an aluminum curing agent is added to such a compound, and also a fluorine compound in addition to an aluminum curing agent for the purpose of further improving water repellency. KR-400F (manufactured by Shin-Etsu Chemical Co., Ltd.) to which is added and X-40-2327 (manufactured by Shin-Etsu Chemical Co., Ltd.) to which a curing agent that accelerates the curing speed is added are also preferred examples.

However, when the above-described partially hydrolyzed condensate of a trifunctional silane compound and a newly prepared partially hydrolyzed condensate of a trifunctional silane compound are subjected to the gas chromatogram analysis described above, Needless to say, it is important to perform moisture management not only for the raw materials but also for the preparation and storage of paints, since a considerable amount of hydrolysis products such as alcohol and carboxylic acid are detected.

The trifunctional silane compound represented by the general formula (A) and its partially hydrolyzed condensate have been previously described as being able to be analyzed and identified by gas chromatogram, etc. It can also be defined by a certain viscosity or the like. The viscosity of the liquid material is known to be temperature-dependent, and since the present invention is used at room temperature, the viscosity should be defined at 25 ° C.

When a preferable range of the compound represented by the general formula (A) is defined using such a viscosity parameter, it is desirable that the compound is 0.6 cps or more with slightly advanced condensation. Furthermore, a compound in which condensation has progressed to a viscosity of 0.75 cps or more is more preferable. Further, if the condensation is excessively advanced and the viscosity becomes 5 cps or more, the composition system becomes unstable, and compatibility with the component (1) is poor. In consideration of wiping property during coating, the viscosity is preferably 3 cps or less. Incidentally, it is known that a methyltrimethoxysilane compound that has not undergone condensation at all has a viscosity at 20 ° C. of 0.5 cps, and when converted to 25 ° C. using the Andrade equation, it is about 0.48 cps. Become. On the other hand, KR-400N, which is a commercially available hydrolysis condensate, is 0.9 cps, and is a preferable material as component (2) from the viewpoint of not only durability but also wiping property.

Examples of the structure of the partial hydrolysis-condensation product of the trifunctional silane compound include a chain structure and a cyclic structure. In any structure, a functional group such as an alkoxy group or an acetoxy group that can undergo a crosslinking reaction after coating. have. In particular, the alkoxy group is preferably a lower alkoxy group such as a methoxy group or an ethoxy group from the viewpoint of coating stability, reactivity after application, volatility, and the like.

In addition, a trifunctional silane compound having two or more of an acetoxy group and an alkoxy group in one molecule or a trifunctional silane compound having a different kind of alkoxy group is also preferably used from the viewpoint of curing rate control. . A trifunctional silane compound having two types of functional groups of an acetoxy group and an alkoxy group in one molecule can be obtained by a substitution reaction by simply adding an appropriate amount of various alcohols to the triacetoxysilane compound and stirring and mixing. it can. Moreover, it can also obtain more easily by performing a heating etc. as needed. A trifunctional silane compound having a different kind of alkoxy group can be obtained by a substitution reaction by adding an appropriate amount of a mixed alcohol corresponding to a trichlorosilane compound, and simply stirring and mixing.

Component analysis and structural analysis of trifunctional silane compounds and partial hydrolytic condensates of trifunctional silane compounds, as well as trifunctional silane compounds obtained by substitution reactions of triacetoxysilane compounds with various alcohols, are described above. In addition to the gas chromatogram, gas chromatogram / mass spectrum, FT-IR, etc. can be used easily and in detail.

Next, the hardening | curing agent containing the organic carboxylic acid bismuth salt compound which is a component (3) is described. As the organic carboxylic acid bismuth salt compound, a known organic carboxylic acid bismuth salt compound can be used, which is excellent in handling safety, and without having to color the obtained coating film, in terms of water repellency, slipperiness and durability. An excellent film can be obtained.

Such an organic carboxylic acid bismuth salt compound is a compound represented by the following general formula (B), and examples of the carboxylic acid include aliphatic carboxylic acids, alicyclic carboxylic acids, and aromatic carboxylic acids. The aliphatic carboxylic acid may have a straight chain or a branched chain, and may be a saturated aliphatic carboxylic acid or an unsaturated aliphatic carboxylic acid. Furthermore, the carboxylic acid may have a hydroxy group.
Bi (OOCR ³ ) ₃ (B)
(In the formula, OOCR ³ represents a carboxylic acid residue of an aliphatic carboxylic acid, an alicyclic carboxylic acid or an aromatic carboxylic acid, and may have a hydroxy group.)

Examples of these carboxylic acids include those having 1 to 21 carbon atoms such as acetic acid, propionic acid, valeric acid, caproic acid, caprylic acid, capric acid, lauric acid, myristic acid, palmitic acid, stearic acid, Saturated aliphatic carboxylic acids such as isostearic acid and eicosanoic acid, oleic acid, linoleic acid, linolenic acid, unsaturated aliphatic carboxylic acids such as acrylic acid and methacrylic acid, alicyclic carboxylic acids such as cyclohexanecarboxylic acid, benzoic acid And aromatic carboxylic acids such as salicylic acid and mandelic acid, and hydroxy groups such as glycolic acid, lactic acid, malic acid, tartaric acid, citric acid, hydroxystearic acid and ricinoleic acid. Among them, organic carboxylic acid bismuth salt compounds such as bismuth octylate, bismuth 2-ethylhexylate, bismuth neodecanoate, and bismuth rosinate are preferably used from the viewpoint of reactivity, safety, and availability. . These organic carboxylic acid bismuth salt compounds may be used alone or in combination of two or more.

When synthesizing such a bismuth organic carboxylic acid salt compound, it can be easily produced by a known method of reacting bismuth oxide with an organic carboxylic acid. Further, when an unreacted organic carboxylic acid is contained in the product obtained after the reaction, in the present invention, the unreacted organic carboxylic acid may be used after being removed under reduced pressure or washing. However, it is also possible to use it while containing unreacted organic carboxylic acid in consideration of cost.

The use amount of the organic carboxylic acid bismuth salt compound is not particularly limited. However, in the use, the use amount of the organic carboxylic acid bismuth salt compound is defined, including being used in a state containing an unreacted organic carboxylic acid. In such a case, it is preferable to use the bismuth content after setting it.

Materials that can be obtained as the organic carboxylic acid bismuth salt compound which is the component (3) of the present invention include bismuth 2-ethylhexanoate (Bi25%) (manufactured by Wako Pure Chemical Industries, Ltd.), pucat 25 (Bi25%), pucat B7 ( Bi7%), bismuth neodecanoate (Bi16%) (manufactured by Nippon Kagaku Sangyo), K-KAT348, XK-628, XK-640, XC-C227 (manufactured by King Industries), bismuth caprylate (manufactured by Takanan Inorganic), Neostan U -600 (manufactured by Nitto Kasei) and the like.

For the purpose of further enhancing the effect of adding the organic carboxylic acid bismuth salt compound, it is also effective to add a metal compound other than the bismuth salt compound to the component (3) curing agent. Specifically, an alkaline earth metal compound of the same organic carboxylic acid as the bismuth salt compound can be mentioned. Furthermore, the combined use of a different compound such as an aluminum compound is also a preferred embodiment.

As the aluminum compound, as a curing aid having an excellent balance between curability and safety, aluminum trialkoxide such as aluminum triisopropoxide and aluminum tributoxide, aluminum trisacetylacetonate, aluminum trisethylacetoacetate, aluminum bis Examples thereof include aluminum chelate compounds such as ethyl acetoacetate monoacetylacetonate, aluminum alkyl acetoacetate diisopropylate, and aluminum ethyl acetoacetate diisopropylate. In particular, an aluminum chelate compound is preferable because it is excellent in storage stability of the paint, and among these, aluminum trisacetylacetonate and aluminum trisethylacetoacetate are most preferable from the viewpoint of easy handling.

In addition, since the present invention uses a dimethyl silicone polymer having silanol groups at both ends having a number average molecular weight (Mn) of 60,000 or more, preferred aluminum compounds are those that can be dissolved in a hydrocarbon solvent. In particular, those that can be dissolved in an isoparaffin solvent are preferred.

Such an aluminum-based curing agent can be used in combination with the organic carboxylic acid bismuth salt compound which is the component (3) of the present invention, and is effective in improving the durability of the coating film without deteriorating the wiping property.

The addition amount of the aluminum-based curing agent is desirably 0.1 to 20 parts by weight with respect to 10 parts by weight of the organic carboxylic acid bismuth salt compound as the component (3). In particular, in order to improve the pot life of the paint, 0.25 to 10 parts by weight, more preferably 0.4 to 6 parts by weight is desirable.

The trifunctional silane compound of component (2) and / or a partially hydrolyzed condensate thereof used in the present invention is a useful coating material only when used in combination with the organic carboxylic acid bismuth salt compound of component (3). A film can be formed. That is, a strong three-dimensional cross-linking can be achieved even if any of the trifunctional silane compound and / or its partially hydrolyzed condensate as component (2) and the organic carboxylic acid bismuth salt compound as component (3) is not included. Can't get structure.

The reason why the trifunctional silane compound (2) of the present invention and / or a partial hydrolysis condensate thereof is used is not only for making a strong three-dimensional crosslinked structure, but also for a large substrate to which the present invention is applied. Specifically, in application to a car body or the like, it works effectively for simple and uniform application.

It should be noted that whether or not it has a strong three-dimensional cross-linked structure depends on a solvent capable of dissolving component (1) and component (2), such as Isopar E, an isoparaffinic hydrocarbon solvent, or ethyl acetate solvent at room temperature for several hours or more. It can be ascertained by measuring the residual solid content after immersion, the water repellency of the coating film, etc., and the former is generally called the gel fraction.

In order to obtain high durability, the gel fraction is 30% or more, more preferably 40% or more, and the water contact angle retention after one month of the outdoor exposure test is 90% or more, more preferably 93%. It is desirable to have the above.

In addition, the addition composition ratio of each component of the trifunctional silane compound which is component (2) and / or its partial hydrolysis condensate and the organic carboxylic acid bismuth salt compound which is component (3) is the kind of component (1) The composition addition weight ratio is usually determined based on the trifunctional silane compound and / or its partial hydrolysis-condensation product with respect to 1 part by weight of the organic carboxylic acid bismuth salt compound. Is preferably in the range of 0.5 to 50 parts by weight, more preferably in the range of 1 to 40 parts by weight, and most preferably in the range of 2 to 30 parts by weight. If the composition ratio of the organic carboxylic acid bismuth salt compound is too small, the curing rate will be too slow, so that the amount of paint remaining at the time of wiping will be too small, so that high water repellency tends not to be obtained. .

That is, when the weight ratio of the trifunctional silane compound and / or its partially hydrolyzed condensate and the organic carboxylic acid bismuth salt compound is less than 0.5, the durability tends to be inferior because there are few crosslinker components. In addition to the water repellency that is the purpose of the above, it becomes difficult to obtain a coating film having excellent durability. Further, when the weight ratio of the trifunctional silane compound and / or its partially hydrolyzed condensate and the organic carboxylic acid bismuth salt compound exceeds 50, the wiping property tends to be inferior, and the coating is simple and uniform. It becomes difficult.

In addition, in the composition comprising the trifunctional silane compound of component (2) and / or its partially hydrolyzed condensate and the organic carboxylic acid bismuth salt compound of component (3), stability as a paint, coating after curing From the viewpoint of improving the water repellency of the film and the compatibility with the component (1), a compound having active protons such as moisture and alcohol is contained as long as the progress of three-dimensionalization in the paint can be controlled. There is no problem. In general, trifunctional silane compounds are highly volatile, and it may be preferable that they are hydrolyzed with a small amount of water and further condensed in order to obtain a coating film having stable performance.

Next, component (4) of the present invention will be described. The water-repellent coating agent of the present invention is stored and used in a state in which the component (1), the component (2) and the component (3) are diluted with the solvent which is the component (4). Mixable organic compounds are applied.

In the water-repellent coating agent of the present invention, a dimethyl silicone polymer having a silanol group at both ends and having a number average molecular weight (Mn) of 50,000 to 200,000 is used as the component (1). The viscosity increases as the number average molecular weight increases. Therefore, it is practically impossible to make a paint in a solvent-free system, and it is not practical. Therefore, it is used by diluting with a solvent from the viewpoint of uniform coating and stability of paint.

Since the water-repellent coating agent of the present invention is usually used under mild conditions such as a room temperature environment, at least 50 wt% of the solvent has a boiling point of 60 ° C. to 300 ° C. at 1 atmosphere, more preferably A relatively highly volatile solvent having a temperature of 70 ° C. to 250 ° C. is preferable.

In addition, since the trifunctional silane compound and / or its partial hydrolysis-condensation product, which is the component (2) of the present invention, has high reactivity with compounds having active protons such as water and alcohol, the main solvent is paint. In order to maintain the stability of the coating film and to improve the durability of the coating film, a compound which is inactive with respect to the component (2) and the component (3) having no active proton is preferably used.

However, by reacting a material having an active proton such as water or alcohol with the acetoxy group or alkoxy group of component (2), the component (2) compound is modified and at the same time reaction products such as organic acid and alcohol Can also be used as part of the solvent.

Typical main solvents that can be used include ether compounds, ester compounds, aliphatic hydrocarbon compounds, aromatic hydrocarbon compounds, ketone compounds, and organic halide compounds. Of these, ether compounds, ester compounds, and aliphatic hydrocarbon compounds are preferred from the standpoint of safety.

Specific examples of the ether compound include dipropyl ether, dibutyl ether, diamyl ether and the like.

Specific examples of the ester compound include ethyl acetate, propyl acetate, butyl acetate, amyl acetate, isoamyl acetate, heptyl acetate, ethyl butyrate, isoamyl isovalerate and the like.

Specific examples of the aliphatic hydrocarbon compound include normal heptane, normal octane, normal nonane, normal decane, etc., and a mixture of isoparaffinic hydrocarbon compounds having several boiling points.

Specific examples of the aromatic hydrocarbon compound include toluene, xylene, dimethylbenzene, trimethylbenzene, and ethylbenzene.

Specific examples of the ketone compound include methyl ethyl ketone and methyl isobutyl ketone.

Specific examples of the organic halide compounds include trichloroethane and trichlorethylene.

Considering that the present invention is often used in an open system in a natural environment, aromatic ethyl acetate, propyl acetate, butyl acetate, amyl acetate, isoamyl acetate, heptyl acetate, ethyl butyrate, isoamyl isovalerate A solvent comprising an ester system such as

On the other hand, aliphatic hydrocarbon compounds having a low odor and low toxicity are particularly useful solvents for workers sensitive to odor. Examples of such aliphatic hydrocarbon compounds include a mixture of isoparaffinic hydrocarbon compounds having several kinds of boiling points described above, and specific examples include Isopar E, G, H, L, M, V, or naphthene. Examples include Exol D30, D40, D60, D80, D110, D130, mineral spirits, and the like, which are mixtures of a series of compounds.

These solvents may be used alone or in combination of two or more without any problem. In particular, organic acids such as formic acid, acetic acid, propionic acid, benzoic acid, lauric acid and stearic acid as well as lower alcohols such as methanol, ethanol, propanol and butanol, etc., as long as the paint is not clouded or separated into two layers. It is also useful to add as a coating solvent because it can improve the storage stability of the coating. In particular, when alcohol is added, if the trifunctional silane compound has an alkoxy group, it is equivalent to a hydrolysis functional group, or the addition of a lower alcohol does not lower the reactivity after coating, and the storage stability of the paint is reduced. It is preferable because it is effective in improving the property.

Furthermore, methanol, ethanol, propanol, isopropanol, etc. in a solvent are used to produce organic acids such as formic acid, acetic acid, propionic acid, benzoic acid, lauric acid, stearic acid by reaction with acyloxysilane described above. It is also possible to add an appropriate amount of butanol or an alcohol such as propylene glycol monomethyl ether or propylene glycol monoethyl ether to the solvent.

As the organic acid or alcohol used as a part of the solvent, a long-chain organic carboxylic acid is preferably used because of a good balance between the stability of the coating and the curability. Further, the content is preferably in the range of 0.1 mol to 50 mol with respect to 1 mol of the organic carboxylic acid bismuth salt compound of component (3). More preferably, it is used in the range of 0.2 mol to 10 mol. Furthermore, it is a possible embodiment that the organic carboxylic acid contained in the organic carboxylic acid bismuth salt compound is used as the long-chain organic carboxylic acid.

In addition, the trifunctional silane compound of the component (2) of the present invention has a relatively low boiling point depending on the type of alkoxy group, has volatility, and has excellent compatibility with the component (1). These trifunctional silane compounds can also be used as part of the solvent.

The solvent content is defined as the solid content, but in order to ensure the stability of the paint, to ensure the film thickness necessary to obtain sufficient water repellency, and to obtain a uniform coating film without spots, However, the solid content is usually used in the range of 0.5 wt% to 30 wt%. In particular, 1 wt% to 25 wt% is preferably used in order to ensure slipperiness of the coating film surface in addition to water repellency. Furthermore, in order to ensure performance including durability, 2 wt% to 20 wt% is more preferably used. The solid content applicable to various coating methods and coating conditions is most preferably in the range of 3 wt% to 17.5 wt%.

The solid content measurement is difficult to define strictly because the present invention is used under mild conditions such as in a natural environment, but usually a small amount of coating agent is poured into a container such as an aluminum cup. The remaining weight after being left under the use conditions can be measured, and the solid content can be obtained with a value reaching a certain value. It is also possible to heat in a dryer or the like for the purpose of shortening the measurement time. As a measurement condition in production management, it is possible to obtain a time during which the remaining weight becomes constant at 100 ° C. and use this condition to obtain a solid content.

Since the component (1) of the present invention has substantially no volatility, its solid content is 100%. However, the solid content of the trifunctional silane compound of the present invention component (2) and / or its partially hydrolyzed condensate, and the organic carboxylic acid bismuth salt compound of component (3) are both moisture in the air. It is conceivable that at least a part thereof reacts by hydrolysis or the like and then also reacts with the component (1), so it is realistic to obtain a solid value with a constant value obtained after the reaction. .

The water-repellent coating agent of the present invention can be stored and used as a composition comprising component (1), component (2), component (3) and component (4), but for the purpose of preventing deterioration during storage, Before use, prepare two solutions of a solution containing component (1), component (2) and component (4) as a main component and a curing agent component solution composed of component (3) and component (4). A more stable coating agent by mixing is also a preferred embodiment in practical use.

In the water-repellent coating agent of the present invention, as a coating film forming component other than the component (1), the component (2) and the component (3), silanols are present at both ends having a number average molecular weight (Mn) of less than 50,000. There are many materials that can be added such as tetrafunctional silane compounds, bifunctional silane compounds, and various surfactants in addition to the dimethylsilicone polymer having a group, and a phenyl group or trifluoropropyl group-containing silicone polymer. .

In particular, the tetrafunctional silane compound can be used in combination as long as the water repellency is not significantly reduced for the purpose of further improving the adhesion and hardness with the substrate. Specific examples of the representative compounds include tetraacetoxysilane, tetramethoxysilane, tetraethoxysilane, tetrapropoxysilane, tetraisopropoxysilane, tetrabutoxysilane, tetrasec-butoxysilane and partial hydrolysis of such tetrafunctional silane compounds. Examples include decomposition condensates.

Moreover, a bifunctional silane compound is mentioned as an additive effective in control of the cure rate for the purpose of improving the wiping property during coating. Specific examples of the silane compound include dimethyldimethoxysilane, dimethyldiethoxysilane, dimethyldipropoxysilane, dimethyldibutoxysilane, dimethyldiacetoxysilane, methylethyldimethoxysilane, methylethyldiethoxysilane, methylethyldipropoxysilane, Methylethyldibutoxysilane, methylethyldiacetoxysilane, methylpropyldimethoxysilane, methylpropyldiethoxysilane, methylpropyldipropoxysilane, methylpropyldibutoxysilane, methylpropyldiacetoxysilane, methylphenyldimethoxysilane, methylphenyldimethoxysilane , Methylphenyldiethoxysilane, methylphenyldipropoxysilane, methylphenyldibutoxysilane, methylphenyldiase Kishishiran and the like. Among them, a dimethylsilane compound is preferably used because it does not lower the water repellency.

These tetrafunctional silane compounds and bifunctional silane compounds can be used by simply mixing them with a trifunctional silane compound. However, when the trifunctional silane compound is used as a partially hydrolyzed condensate, each of them is preliminarily uniform. It is a useful means for improving the uniformity as a coating material by preparing a mixed solution and then hydrolyzing / dehydrating and condensing it into a co-condensation partial hydrolysis-condensation product.

In the water-repellent coating agent of the present invention, various surfactants are preferably used for the purpose of improving the wettability to the substrate and the smoothness of the coating film. As the surfactant, one or more selected from fluorine leveling agents, silicone leveling agents, polymer ether leveling agents, nonionic leveling agents and the like that are soluble in the solvent of the component (4) of the present invention. Is preferably used.

In particular, a fluorine leveling agent is preferably used as a material that can enhance the surface active effect without lowering the water repellency of the coating film. For example, Megafac F-554 (manufactured by DIC) is preferable. As an agent.

Further, the addition amount of various surfactants is desirably 10 ppm to 10 ⁴ ppm with respect to the water-repellent coating agent of the present invention. If it is less than 10 ppm, the effect of adding to the leveling property of the surfactant is small, and if it exceeds 10 ⁴ ppm, the surfactant bleeds out to the surface, and the touch and water repellency tend to decrease.

The water-repellent coating agent of the present invention can be cured easily by simply leaving it under room temperature conditions without applying a special curing treatment device after application to the substrate surface. As specific temperature conditions, a temperature at which the solvent can be volatilized is sufficient, but usually 5 ° C. or higher, preferably 10 ° C. or higher is recommended as a practical temperature condition. It is also a preferred embodiment to heat in order to shorten the curing time or to apply wind to speed up drying.

Next, the slipperiness in the present invention will be described. The slipperiness can be expressed by a surface friction coefficient. As a practical evaluation of surface friction, it is possible to qualitatively measure good and bad by rubbing lightly with human fingers or nails, etc., but the surface is used as a method to eliminate arbitraryness It is a coefficient of friction. The surface friction coefficient can be measured quantitatively with good reproducibility by using TRIBOGEAR (manufactured by HEIDON) TYPE: 14FW as a measuring device.

The method for applying the water-repellent coating agent to the substrate is not particularly limited. Specific methods include dipping coating, spray coating, flow coating, brush coating, spin coating, and impregnation with paint. For example, a transfer coating method using a cloth or a sponge, and the like should be selected as appropriate depending on the size and shape of the substrate.

Furthermore, another method for producing a coating film according to the present invention will be described. That is, the present invention applies a water-repellent coating agent containing the following components (1) to (4), and then spreads (so-called wiping) using a cloth made of ultrafine long fibers. It is a manufacturing method of a film | membrane.
(1) Number average molecular weight (Mn) having silanol groups at both ends is 50,000 to 200,00
0 dimethyl silicone polymer (2) trifunctional silane compound and / or partial hydrolysis condensate thereof (3) curing agent containing organic carboxylic acid bismuth salt compound (4) solvent

As an application method of the water-repellent coating agent of the present invention, an article having an irregular shape such as a molded product is not subjected to a brush coating method, a transfer coating method using a cloth or sponge impregnated with a paint, or a spray coating to eliminate a non-coated portion. Is preferable.

In particular, as a method to ensure the uniformity and smoothness of the coating film, brush coating, transfer coating with a cloth or sponge impregnated with paint, or ultra-fine long fibers that enable thin film coating after spray coating A method of spreading (so-called wiping) using a cloth made of the above is practical and a method for obtaining a good appearance.

Here, examples of the form of the cloth made of ultrafine long fibers include woven fabrics and knittings made of yarn generally called microfibers, and there is no problem whether it is a sheet or a towel. Furthermore, as the woven fabric, a double woven fabric in which the front and back are knotted, or a so-called twill woven fabric in which the warp is woven by crossing the top and bottom of the weft, and a woven fabric composed of five or more warps and wefts. There is a satin weave. In particular, when a coating film formed by transferring a large amount of paint is applied (so-called wiping), a cloth having a towel-like woven fabric is preferably used.

In addition, as fabric materials used for spreading, natural fibers, synthetic fibers, blended fibers of natural fibers and synthetic fibers, and fibers obtained by combining two or more synthetic fibers such as polyester and polyamide are also used. can do. In particular, synthetic fibers are most preferable because fibers having a sea-island structure or fibers having a split structure can be made very fine. Furthermore, the fiber diameter is preferably 1.0 to 7.5 microns for uniform coating thickness. Among these, a fiber diameter that is more desirable for uniform coating thickness is preferably 1.5 to 7.0 microns.

Since the water-repellent coating agent of the present invention has hydrophobicity and is accelerated by moisture in the air, it is soluble after simultaneously spinning a 100% polyester material and a polymer soluble in an organic solvent. The ultra-fine long fibers consisting of the so-called sea-island structure with the polymer component dissolved and removed are not only preferable because they are excellent in imparting surface uniformity of the membrane, but also useful for improving durability. Is preferably used.

In addition, in a water-repellent coating agent using a high molecular weight dimethyl silicone polymer having a silanol group at both ends and a number average molecular weight (Mn) of 50,000 to 200,000 as a main component, the coating agent is used during spreading (so-called wiping) Is difficult to penetrate to the inside of the cloth material, and tends to be spread (so-called wiping) in a state of adhering to the cloth surface.

Therefore, when applied to large-area substrates, etc., in order to make spreading (so-called wiping up) smoothly, the initial stage where a large amount of coating agent is attached is a split-type structure that easily removes the coating agent by adsorption. A two-stage spreading method is preferred in which ultrafine fibers made of the above are applied, and ultrafine fibers having a sea-island structure with a flat surface are used for the final finish.

It is also useful to use a cloth impregnated with moisture for spreading (so-called wiping) for the purpose of promoting curing by moisture. If the amount of water to be impregnated is such that water drops do not fall even when squeezed, a sufficient effect is expected.

Furthermore, it is also possible to include a small amount of acid or base in the water. Specifically, water containing a volatile acid compound such as dilute hydrochloric acid or dilute acetic acid is spread (so-called wipe-up). It is preferably used because hydrolysis can proceed more smoothly.

Since the water-repellent coating film of the present invention has a structure in which dimethyl silicone polymer is three-dimensionally crosslinked, its refractive index is relatively low, and thus it is possible to reduce light reflection and to have deep glossiness. There is also.

However, if the coating film becomes too thick, stripes and smears due to light interference tend to be noticeable and tend to be inferior in design. Further, when the coating film is too thin, not only the water repellency effect tends to be lowered, but also the surface slipperiness tends to be lowered. In addition, the effect of filling the scratches on the substrate to be coated is small, and the expression of deep gloss due to the reduction of light reflection tends to decrease.

Therefore, the film thickness of the coating film obtained from the water-repellent coating agent of the present invention is thinner than the visible light wavelength, 4 nm to 200 nm, more preferably 6 nm to 100 nm, more preferably 8 nm to the film thickness necessary for ensuring water repellency. 80nm is recommended.

The water-repellent coating agent of the present invention has sufficient water repellency, durability such as surface coating slipperiness, weather resistance, chemical resistance, etc., simply by being applied to a substrate and then cured by natural drying in a room temperature environment. It becomes an aqueous coating film.

As the curing condition of the water-repellent coating agent of the present invention, it can be sufficiently cured under normal natural environmental conditions, but as a measure to further increase the water repellency, in a high humidity environment, specifically 20% RH, more preferably Is preferably cured in a humidity environment of 30% RH or higher. As a means for increasing the humidity, a method of spreading water or warm water on the floor or a water mist spraying can be mentioned as a simple and effective method.

As a method for shortening the curing time of the water-repellent coating agent of the present invention, it is also effective to increase the temperature of the vehicle body including the bonnet by blowing air to speed up drying, or by applying a car engine when applied to a car. As a method.

The coating film obtained by the water-repellent coating agent of the present invention has high water repellency and is excellent in durability, slipperiness, and weather resistance. Therefore, it is usually rubbed with human hands, fingers, cloths and papers, etc. It is preferable to be applied to applications where there are many cases where rainwater or tap water falls.

Although the chemical reaction of the curing reaction of the water-repellent coating agent of the present invention has not been completely elucidated, the trifunctionality in which both end silanol groups of the dimethyl silicone polymer are basically crosslinking agents. It is presumed that the silane compound and / or the hydrolysis product of the partially hydrolyzed condensate thereof and the organic carboxylic acid bismuth salt compound react directly or indirectly.

That is, it is thought that the dimethyl silicone polymer which has a high number average molecular weight (Mn) both terminal silanol group expresses the favorable characteristic by forming a crosslinked structure three-dimensionally.

The details of the hydrolysis and curing reaction scheme of the trifunctional silane compound and / or its partially hydrolyzed condensate component (2) and the organic carboxylic acid bismuth salt compound as component (3) are still uncertain. Although it has not yet been achieved, it is presumed that it is progressing in a complex reaction system, probably in concert.

The water-repellent coating film of the present invention has low surface energy, excellent water repellency, and the coating film is highly three-dimensionally crosslinked. In addition, it has high durability with excellent weather resistance and chemical resistance.

As a method for evaluating water repellency in the present invention, the most common method is to measure the so-called static contact angle of water generated between water and the coating film surface by forming minute water droplets on the coating film surface. It is. In addition, the static contact angle of water can be measured by using an “automatic contact angle meter” (FACE) CA-Z type as a measuring device.

The coating film excellent in water repellency in the present invention means a film having a high static contact angle of water, and specifically, a film having an initial contact angle higher than that of the substrate to be coated. An example of a film having a higher water repellency is a film having a static contact angle of 100 degrees or more, and an ideal film having a high water repellency is a film having a static contact angle of 102 degrees or more.

That is, a film having a static contact angle of water lower than that of the substrate has no meaning to provide a water-repellent coating film, and in a film having a static contact angle of less than 100 degrees, liquid materials such as rainwater, purified water, and alcoholic beverages are used. When it adheres to the film surface, it is difficult to drop from the film surface, so it is not meaningful to provide a water-repellent coating film.

Such a coating film has a problem that water droplets or the like are likely to remain on the surface, not only deteriorating the sense of quality, but also causing a surface appearance defect called rain stain or water burn on the coating film after drying.

Further, the durability in the present invention is a scale for judging whether or not to withstand long-term use, specifically, the water repellency retention after an outdoor exposure test of one month or more is 90% or more, Furthermore, it means that the water repellency retention after immersion in a solvent in which the silicone component is dissolved, such as isopara E hydrocarbons such as isoparaffinic hydrocarbons, ethyl acetate, or a mixture thereof, is 90% or more.

As apparent from the above description, the water-repellent coating agent of the present invention contains the following components, and the effects listed below can be obtained.
(1) “Number average molecular weight (Mn) having silanol groups at both ends is 50,000 to 200,
000 dimethyl silicone polymer, trifunctional silane compound and / or a partially hydrolyzed condensate thereof, and a solution containing a crosslinking agent and a solvent comprising a bismuth organic carboxylic acid salt compound, A water-repellent coating film having excellent sliding properties and excellent durability such as weather resistance and chemical resistance can be formed on the surface of the substrate.

(2) “The coating film obtained by the water repellent coating agent of the above (1) is a coating film having excellent surface slipperiness” and is excellent in slipperiness in addition to water repellency, so that dust is not damaged on the surface. And removal of dirt and the like is easy.

(3) “Coating by applying a water-repellent coating agent and spreading (so-called wiping) using a cloth made of ultrafine long fibers as a method for producing a coating film using the water-repellent coating agent of (1) above. A water-repellent coating film having a uniform surface that is simple and free from coating spots can be obtained.

(4) The water-repellent coating film of the present invention has a low refractive index and has a well-balanced water-repellent coating capable of achieving deep gloss expression in addition to properties such as water repellency, durability and slipperiness. It can be a membrane.

Hereinafter, the present invention will be described in detail with reference to examples, but the present invention is not limited thereto.

(1) Evaluation method (a) Water repellency
The static contact angle (degree) of water was measured using a CA-Z type “automatic contact angle meter” manufactured by FACE, and the value was used as water repellency.
(B) Sliding coating The surface of the coating film was evaluated by the strength of catching when it was scratched with fingers or nails.
○: Slightly less slipping and better slipperiness than untreated products.
(Triangle | delta): There exists a catch of the same level as an untreated product.
X: Feels a stronger catch than untreated products.
In addition, the intermediate level of (circle) and (triangle | delta) was displayed as (circle)-(triangle | delta).
(C) Film-formability The uniformity of the coating film when applied to the test piece substrate described below was evaluated with the naked eye.
○: No spots are observed.
(Triangle | delta): A fine spot is recognized.
X: Occurrence of obvious spots is observed.
In addition, the intermediate level of (circle) and (triangle | delta) was displayed as (circle)-(triangle | delta).
(D) Durability The static contact angle of water on the membrane surface after outdoor exposure for 1 month on the south-facing slope was measured, and the water repellency retention rate (%) was determined. The higher the retention rate, the better the water repellency durability.

(Experimental Examples 1 to 6), (Comparative Examples 1 to 2)
(1) Coating agent adjustment experiment example 1:
A dimethyl silicone polymer (DMS-S51 manufactured by GELEST Inc.) having silanol groups at both ends having a number average molecular weight (Mn) of 120,000 in a vessel with a lid provided with a rotor and methyl prepared by the method described in (2) below Table 1 shows the partial hydrolysis-condensation product of trimethoxysilane, bismuth organic carboxylate (trade name: XK-628, manufactured by King Industries) and isoparaffin hydrocarbon solvent (product name: Isopar E, manufactured by ExxonMobil) The indicated amount was added and sufficiently stirred to obtain a paint.
Experimental example 2:
The same procedure as in Experimental Example 1 was conducted except that the organic bismuth carboxylate compound was changed to bismuth octylate prepared by the method described in (3) below.
Experimental Example 3:
Change the partial hydrolysis-condensation product of the trifunctional silane compound to KR-400 containing aluminum curing agent (manufactured by Shin-Etsu Chemical Co., Ltd., viscosity (25 ° C): 1.2 cps), and the composition ratios shown in Table 1 Except for changing to, everything was carried out in the same manner as in Experimental Example 1.
Experimental Example 4:
The same procedure was carried out except that in Example 2, the solvent was changed to butyl acetate.
Experimental Example 5:
The same procedure as in Example 3 was conducted except that the organic carboxylic acid bismuth salt compound was changed to bismuth neodecanoate.
Experimental Example 6:
The experiment was conducted in the same manner as in Experimental Example 1 except that the organic carboxylic acid bismuth salt compound was changed to the product name: Neostan U-600 (manufactured by Nitto Kasei Co., Ltd.).
(Comparative Examples 1 to 2)
The uncoated product evaluated as a blank was used as Comparative Example 1, and as Comparative Example 2, the same procedure was performed for the composition in which the organic carboxylic acid bismuth salt compound in Experimental Example 1 was not added.
(2) Preparation of methyltrimethoxysilane partially hydrolyzed condensate 136 g of methyltrimethoxysilane was weighed in a beaker, and 18 g of 0.01 N hydrochloric acid aqueous solution was added at a time while stirring with a magnetic stirrer at room temperature. After the addition, as the hydrolysis progressed, the opaque solution turned into a clear solution with a slight exotherm. Stirring was continued with the beaker sealed until the solution temperature reached room temperature. When the temperature reached room temperature, stirring was stopped, and the mixture was aged at room temperature overnight to obtain a hydrolyzate. After aging overnight, methanol as a hydrolysis product was removed with an evaporator (45 ° C., 75 mmHg, 30 minutes) to obtain a methyltrimethoxysilane partial hydrolysis condensate.
(3) Preparation of bismuth octylate While stirring in 70 parts by weight of octyl acid, 30 parts by weight of bismuth oxide was added, mixed and stirred at 180 ° C. for several hours, and mixed until a viscous liquid was obtained. Bismuth acid (C8Bi) was obtained.

(4) Preparation of substrate to be coated Applying LV Prasaf from Isamu Paint Co., Ltd. as a primer to a 0.1 mm thick tin plate, then Milano 2K from Isamu Paint Co., Ltd. as an intermediate coating, and top clear layer As a result, a coated test piece substrate for a water-repellent coating film was created by applying Milan 2K Como Clear No. 1 manufactured by Isamu Paint Co., Ltd.

(5) Coating film adjustment A microfiber towel made of a split microfiber fabric of polyester / nylon = 80% / 20% after coating a sponge with a coating agent on the substrate to be coated of (4) above. After using Maruno Towel Co., Ltd., Microfiber Green Color Towel, No.RO463-1-S), it was spread to the absence of smears and then allowed to dry naturally for one week to form a coating film. Obtained.

(6) Evaluation results Table 1 shows the evaluation results of the obtained coating films. The coating film obtained by the water-repellent coating agent of the present invention is uniformly applied on the substrate to be coated because of its excellent film forming property. Furthermore, as shown in Table 1, it has a very excellent water repellency and slipperiness. It became clear that it was excellent in the property and durability (Experimental example 1-Experimental example 6). The static contact angle of the surface of the untreated substrate to be coated was 95 degrees, which was a surface without water repellency (Comparative Example 1). In addition, the film obtained from the composition not added with the organic carboxylic acid bismuth salt compound had a surface state equivalent to that of the uncoated product, and the effect of applying the water-repellent coating treatment was not recognized (Comparative Example 2).

The water-repellent coating agent of the present invention is suitable for obtaining a coating film excellent in water repellency, slipperiness and durability on various substrate surfaces. In particular, since the water-repellent coating film of the present invention is stable against light and heat, it has high durability, and further becomes a coating film excellent in deep glossiness. In addition, it can be cured at room temperature, has a wide range of choice of coating methods, and has a high degree of freedom. A uniform coating without smears can be obtained, so trains, cars, buses, etc. It can also be applied to the windows and exterior parts of other vehicles, as well as the outer walls of buildings and ordinary houses, and window glass. It can also be applied to painted metal parts such as vehicle wheels.

Claims (10)

A water repellent coating composition comprising the following components (1) to (4):
(1) Dimethyl silicone polymer having silanol groups at both ends and a number average molecular weight (Mn) of 50,000 to 200,000 (2) Trifunctional silane compound and / or partial hydrolysis condensate thereof (3) Bismuth salt of organic carboxylic acid Containing curing agent (4) solvent The water repellent coating agent according to claim 1, wherein the component (2) contains 5 to 1,000 parts by weight with respect to 100 parts by weight of the component (1). The water repellent coating agent according to claim 1 or 2, wherein the component (2) contains 0.5 to 50 parts by weight with respect to 1 part by weight of the component (3). The trifunctional silane compound of component (2) and / or a partially hydrolyzed condensate thereof has an alkyl group or an alkenyl group having 1 to 3 carbon atoms, and the hydrolytic functional group has an alkoxy group having 1 to 2 carbon atoms or The water repellent coating agent according to claim 1, 2 or 3, wherein the water repellent coating agent is one or more selected from acetoxy groups. The trifunctional silane compound of component (2) and / or the partially hydrolyzed condensate thereof has a viscosity at 25 ° C of at least one selected from 0.6 cps or more and less than 5 cps. The water-repellent coating agent according to claim 3 or 4. The organic bismuth carboxylic acid salt compound of component (3) contains one or more selected from compounds represented by the following general formula (B), characterized in that: The water repellent coating agent according to claim 2, claim 3, claim 4 or claim 5.
Bi (OOCR ³ ) ₃ (B)
(However, in the formula, OOCR ³ represents a carboxylic acid residue of an aliphatic carboxylic acid, an alicyclic carboxylic acid or an aromatic carboxylic acid, and may have a hydroxy group. The curing agent of component (3) comprises an organic carboxylic acid bismuth salt compound and an aluminum compound, and the weight ratio of the organic carboxylic acid bismuth salt compound to the aluminum compound is 0.1 parts by weight with respect to 10 parts by weight of the organic carboxylic acid bismuth salt compound. The water repellent coating agent according to claim 1, 2, 3, 4, 5, or 6, which is ˜20 parts by weight. The solvent of the component (4) comprises an amount of 0.5 wt% to 30 wt% as a solid content of the coating material, characterized in that it is 0.5 wt% to 30 wt%. Item 8. The water-repellent coating agent according to Item 6 or 7. The component (4) having 50% by weight or more has a boiling point of 60 ° C. to 300 ° C. 1, 2, 3, 4, 5, 6, 7 Or the water-repellent coating agent of Claim 8. In the coating film formation method using the water-repellent coating agent according to claim 1, claim 2, claim 3, claim 4, claim 5, claim 6, claim 7, claim 8, or claim 9. A method for producing a water-repellent coating film, characterized by spreading using a cloth composed of long fibers having a fiber diameter of 1.0 to 7.5 μm.