JPH11286651A - Water repellent coating agent - Google Patents

Abstract

(57) [Problem] To obtain a resin having a beautiful finish, good workability, durability, and a water-repellent cured film resistant to acid rain by obtaining a resin which forms a cured film on the surface. Provided is a water-repellent coating agent that can be formed on a painted surface. (A) Curable polyorganosiloxane 10
0 parts by weight, (B) polydiorganosiloxane 20 to 10
0 parts by weight, volatile polydimethylsiloxane 200 to 30
A water-repellent coating agent containing 00 parts by weight, (D) a curing catalyst, and (E) 3 to 15 parts by weight of γ-aminopropyltrimethoxysilane.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a water-repellent coating agent for a substrate, and more particularly to a water-repellent coating agent capable of imparting good appearance, water repellency and water repellency to a metal-coated surface.

[0002]

2. Description of the Related Art Carnauba wax, montan wax, paraffin wax, and the like have been conventionally used as water-repellent coating agents used on metal painted surfaces of automobiles and the like.
It is generally a solution type obtained by dissolving or dispersing a natural or synthetic wax such as microcrystalline wax and polyethylene wax and a silicone oil or silicone wax in a solvent, or an emulsion type dispersing in water using an emulsifier. It was a target.

[0003] However, these water-repellent coating agents have a fragile surface, are damaged by dust and acid rain, and wear and fall off when the painted surface is washed many times. There was a problem that impaired.

[0004] A trial of a coating agent having water-repellent durability is as follows.
Although reported in JP-B-56-15827, the composition described here was insufficient in water repellency.

[0005]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned problems and obtains a resin capable of forming a cured film on the surface, whereby the finish is beautiful, the workability is good, the durability is high, and the acid rain is obtained. It is an object of the present invention to provide a water-repellent coating agent capable of forming a water-repellent cured film having a strong water repellency on a metal painted surface.

[0006]

Means for Solving the Problems The present inventors have conducted various studies to achieve the above object, and as a result, by combining specific siloxane components and adding an appropriate amount of γ-aminopropyltrimethoxysilane, excellent results have been obtained. Appearance, water repellency,
In particular, they have found that water repellency can be imparted, and have accomplished the present invention.

That is, the water-repellent coating agent of the present invention has the following general formula (A):

Embedded image (Wherein, R represents a monovalent organic group or a hydrogen atom;
Represents a hydroxyl group or a hydrolyzable group, and a and b are numbers satisfying the relationship of 0.8 <a <2 and 0.3 ≦ b <2), 100 parts by weight of a curable polyorganosiloxane represented by the following formula: , (B) general formula

Embedded image (Wherein, R ¹ represents a monovalent organic group, Y represents a hydroxyl group or a hydrolyzable group, and c is an integer satisfying 2 ≦ c ≦ 200). Parts by weight, (C) general formula

Embedded image (Wherein m represents an integer of 0 to 9) and / or

Embedded image (Wherein n represents an integer of 3 to 8), 200 to 3000 parts by weight of a volatile polydimethylsiloxane represented by the formula (D):
It is characterized by containing a curing catalyst and (E) 3 to 15 parts by weight of γ-aminopropyltrimethoxysilane.

Hereinafter, the present invention will be described in detail.

The curable polyorganosiloxane of the component (A) used in the present invention has a hydroxyl group or a hydrolyzable group and is represented by the following general formula.

[0010]

Embedded image Here, R represents a monovalent organic group or a hydrogen atom. 1
Examples of the valent organic group include an alkyl group such as methyl, ethyl, propyl, butyl, and hexyl; an alkenyl group such as vinyl and allyl; an aryl group such as phenyl, tolyl and xylyl; an aralkyl group such as phenethyl and β-phenylpropyl; Examples thereof include fluoroalkyl groups such as 3,3,3-trifluoropropyl. Among these,
An alkyl group is preferable, and a methyl group is particularly preferable, since the gloss of the protective film is good.

In order to form a smooth protective film and obtain a good appearance, it is preferable that 90 mol% or more of R is a methyl group. Further, it is desirable that the component (A) has good compatibility with the volatile polydimethylsiloxane of the component (C).

X in the component (A) represents a hydroxyl group or a hydrolyzable group. Examples of the hydrolyzable group include an alkoxy group, an acyloxy group, a ketoxime group, an amide group,
Examples thereof include an alkenyloxy group and a halogen atom. A hydroxyl group or an alkoxy group is preferable, and a hydroxyl group, a methoxy group, or an ethoxy group is particularly preferable, since a by-product generated during the curing reaction has a low odor and excellent curability and film properties.

Further, it is necessary that a and b are numbers that satisfy the relations of 0.8 <a <2 and 0.3 ≦ b <2.

When a is 0.8 or less, the cured film becomes brittle,
If it is 2 or more, a good cured film cannot be obtained, and at the same time, oil will ooze into the film, causing slipperiness, which is not suitable for the purpose of the present invention. If b is less than 0.3, the curing speed is too slow to be suitable for practical use, and a cured film with good abrasion resistance and light quality cannot be obtained. The detergency deteriorates and is not suitable for the purpose of the present invention.

As the component (A), any liquid or solid can be used as long as it can be dissolved and mixed with the component (C). The viscosity of the component (A) is usually preferably 10 cSt or more in order to form a good coating film with little repelling, and the formed protective coating is made less sticky to improve coating properties. Has 100,000 cSt
The following is preferred.

Such a polyorganosiloxane can be obtained by a known method, and is obtained by partially hydrolyzing a hydrolyzable organosilane such as organoalkoxysilane or organochlorosilane as a raw material.

The polydiorganosiloxane of the component (B) used in the present invention has a hydroxyl group or a hydrolyzable group and is represented by the following general formula (II).

[0018]

Embedded image Here, R ¹ represents a monovalent organic group, and methyl, ethyl,
Examples thereof include alkyl groups such as propyl, butyl, hexyl, octyl, decyl, and dodecyl; cycloalkyl groups such as cyclohexyl and cyclooctyl; aryl groups such as phenyl and tolyl; and alkenyl groups such as vinyl, allyl and propenyl. Among these, alkyl groups,
An aryl group is preferable, and a methyl group and a phenyl group are particularly preferable. In one molecule of the component (B), all of R ¹ may be the same or a plurality of groups may be mixed.

Y represents a hydroxyl group or a hydrolyzable group. Examples of the hydrolyzable group are the same as those of X shown in the component (A), and the hydroxyl group is preferable because the curability of the composition is good, and the gloss of the protective film is good. Thus, a methoxy group or an ethoxy group is preferred. In one molecule of the component (B), all of X may be the same or a plurality of types of groups may be mixed.

Further, c is an integer satisfying 2 ≦ c ≦ 200, and since good antifouling property is obtained, 5 ≦ c ≦ 20
It is preferably an integer satisfying the following.

The compounding amount of the polydiorganosiloxane (B) is 20 to 100 parts by weight, preferably 30 to 80 parts by weight, more preferably 100 parts by weight of the curable polyorganosiloxane (A). Is from 40 to 70 parts by weight. If the amount is less than 30 parts by weight, a good appearance cannot be obtained, and the protective film becomes brittle. If the amount is more than 100 parts by weight, the strength of the film decreases.

The component (C) used in the present invention comprises:
It is a volatile polydimethylsiloxane represented by the following general formulas (III) and / or (IV).

[0023]

Embedded image

Embedded image The volatile polydimethylsiloxane as described above is a linear polydimethylsiloxane having m of 0 to 9 or a cyclic polydimethylsiloxane having n of 3 to 8 whose terminal is blocked with a trimethylsilyl group, and the component (A) Either linear or cyclic polydimethylsiloxane or a mixture thereof is used in consideration of the solubility of the component (B). Among these, the use of a linear polydimethylsiloxane in which m is 2 to 7 or a cyclic polydimethylsiloxane in which n is 3 to 5 is preferable, and the use of a cyclic polydimethylsiloxane in which n is 4 or 5 is particularly preferable. Here, "volatile" means having a vapor pressure that can be measured at room temperature,
The component (C) preferably has a boiling point of 99 to 260 ° C. The volatile polydimethylsiloxane of the component (C) is a particularly essential component for the water-repellent coating agent of the present invention. It is considered that the excellent volatility of the component (C) is one of the properties that provide excellent water repellency. In the non-volatile state, while maintaining a low viscosity, it contributes to the formation of a uniform film on an object, and at the time of film formation, acts to evaporate over time to form a strong water-repellent film.

The amount of the component (C) is 200 parts by weight based on 100 parts by weight of the curable polyorganosiloxane of the component (A).
3,000 parts by weight, preferably 600-2,000 parts by weight.
Parts by weight, more preferably 600 to 1900 parts by weight.

As the component (D) used in the present invention, general curing catalysts used for condensation-curable silicone compositions can be used, and metal salts of carboxylic acids such as tin octylate and zinc octylate; dibutyltin Examples thereof include organic tin compounds such as dilaurate; titanates such as tetrabutyl titanate and tetrapropyl titanate; and dibutyltin dilaurate or tetrabutyl titanate is preferable because of easy handling. Two or more of these catalysts may be used in combination.

The amount of the catalyst is 0.01 to 100 parts by weight of the curable polyorganosiloxane (A) in view of the curing rate of the coating agent and the pot life.
７０70 parts by weight, preferably 0.3-70 parts by weight, more preferably 50-70 parts by weight.

By adding an appropriate amount of the component (E) γ-aminopropyltrimethoxysilane used in the present invention, the water repellency durability is remarkably improved. The compounding amount of the component (E) is 3 to 10 parts by weight based on 100 parts by weight of the curable polyorganosiloxane of the component (A). Preferably, it is 4 to 10 parts by weight. More preferably, 4 to
8 parts by weight. If the amount is more than 10 parts by weight, gelation occurs due to the presence of the siloxane having a hydroxyl group bonded to a silicon atom, resulting in poor storage stability.
By having an amino group, the component (E) strongly binds to a functional group such as a hydroxyl group, a carboxy group, or an aldehyde group on the surface of the object, and contributes to an improvement in durability of the coating.

The coating agent of the present invention may further use a general diluting solvent (F). The solvent component is not particularly limited as long as it can disperse and dissolve the component (A), the component (B), the component (C), the component (D), and the component (E). Methanol, ethanol, isopropanol Alcohols and ethers such as ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, tetrahydrofuran and dioxane; ketones such as acetone, methyl ethyl ketone and diethyl ketone; methyl acetate, ethyl acetate and n-acetic acid Esters such as butyl; n-hexane, gasoline, rubber volatile oil, mineral spirit,
Aliphatic hydrocarbons such as kerosene can be exemplified.
Among them, aliphatic hydrocarbons having excellent compatibility with siloxanes are preferable. These diluting solvents (F) are used in an amount of 50 to 3100 parts by weight, preferably 50 to 2,000 parts by weight, more preferably 1300 to 100 parts by weight, based on 100 parts by weight of the component (A).
2000 parts by weight can be blended.

To prepare the coating agent of the present invention,
For example, first, the volatile polydimethylsiloxane (C) alone or the volatile polydimethylsiloxane (C) and the aliphatic hydrocarbon are put in a container, and the curable polyorganosiloxane (A) and the polydiorganosiloxane (B) are placed therein. Is added and mixed well, and while mixing, γ-aminopropyltrimethoxysilane (E) is added little by little, followed by further mixing. While mixing, the curing catalyst (D) is added little by little to mix and adjust. The prepared coating agent is sealed and stored so that it does not dry and harden when exposed to the outside air. The standard pot life is about 3 hours.

The method for applying the coating agent of the present invention to the surface of an object includes brush coating, spray coating, roller coating and the like.

When the coating agent of the present invention is applied, for example, it is applied to a cloth so that the droplets do not fall down so that the surface of the target substrate is moistened, and the temperature is reduced from 10 ° C. to 50 ° C.
Leave in a well-ventilated place of about 30 ° C. for about 30 minutes, and finish by polishing with a dry cloth so that the surface of the base material becomes smooth. The coating agent of the present invention is cured by curing or air-drying at room temperature for several hours to several days after application to form a good protective film.

The water-repellent coating agent of the present invention has excellent solvent resistance and does not swell in xylene or acetone.

The substrate to which the water-repellent coating agent of the present invention is applied is generally a metal-coated surface such as a car body.

[0034]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to embodiments, but is not necessarily limited thereto.

Example 1 Methyltrimethoxysilane 13 was added to a flask equipped with a stirrer, a heating jacket, a reflux condenser and a dropping funnel.
60 g (10 mol), 95 g of methanol and methyltrichlorosilane were charged so that the hydrochloric acid content became 50 ppm, and 256 g (14.2 mol) of water was gradually dropped with a dropping funnel while stirring. Reflux temperature (about 68-7
(2 ° C.) for 4 hours to carry out hydrolysis and condensation reactions. After the completion of the condensation reaction, the volatile components were removed under reduced pressure at a normal temperature of 100 ° C., to obtain a curable polyorganosiloxane serving as the component (A) having a viscosity of 20 cSt.

This curable polyorganosiloxane 100
Parts by weight, following formula

Embedded image Component (B) polydiorganosiloxane 6 represented by
6.7 parts by weight, following formula

Embedded image 1900 parts by weight of octamethylcyclotetrasiloxane which is a volatile polydimethylsiloxane of the component (C) represented by the following formula:

Embedded image 66.7 parts by weight of dibutyltin dilaurate as a curing catalyst of the component (D) represented by the following formula:

Embedded image 3.3 parts by weight of γ-aminopropyltrimethoxysilane as the component (E) represented by the following formula, and 1300 parts by weight of an aliphatic hydrocarbon solvent (IP Solvent 1620, manufactured by Idemitsu Petrochemical Co., Ltd.) as a diluting solvent (F) Parts were blended and stirred until uniform, to obtain a water-repellent coating agent.

Examples 2 and 3 The water-repellent coating agents of Examples 2 and 3 were obtained using the same materials as in Example 1 with the composition shown in Table 1 in the same manner as in Example 1.

Comparative Examples 1 to 4 Water-repellent coating agents of Comparative Examples 1 to 4 were obtained in the same manner as in Example 1 using the same materials as in Example 1 and the composition shown in Table 1.

[0039]

[Table 1] Comparative Example 5 Carnauba wax 50 parts by weight, liquid paraffin 25 parts by weight, polyoxyethylene (10) stearate 9 parts by weight, polyoxyethylene (40) stearate 9 parts by weight, polyoxyethylene (10) octyl phenyl ether 12 parts by weight Into a container, gradually heated to 90 ° C. to dissolve and stir while maintaining at 90 ° C., while gradually adding 380 parts by weight of water also heated to 90 ° C.,
After stirring for 1 hour, the mixture was cooled and stirred and cooled to 25 ° C. to obtain an emulsified composition.

Comparative Example 6 20 parts by weight of lanolin soap, 15 parts by weight of microwax, 5 parts by weight of polymer resin, 30 parts by weight of petroleum sulfonate, and 30 parts by weight of isoparaffin were mixed in a container and mixed until uniform. I got something.

Comparative Example 7 Formula 7

Embedded image Hydroxyl-containing organopolysiloxane resin containing at least 0.01% by weight of hydroxyl groups bonded to silicon atoms
Part is expressed by the following formula

Embedded image 13 parts of an alkoxy group-containing organopolysiloxane resin containing 35% of methoxy groups, methyltrimethoxysilane; 7.6 parts of CH ₃ Si (OCH ₃ ) ₃ , γ- (aminoethyl) aminopropyltrimethoxysilane; H _Two
N (CH ₂ ) ₂ NH (CH ₂ ) ₃ Si (OCH ₃ )
₃ 2.6 parts and 0.4 parts of dibutyltin diacetate were placed in a container and mixed until uniform to obtain a blended composition.

The water-repellent coating agent prepared in each of the Examples and Comparative Examples was applied to a metal plate coated with a 15 cm × 15 cm square by spreading it in a cloth, allowed to stand at room temperature for at least 24 hours, and cured. The properties of the cured film were evaluated. Table 2 shows the results.

[0043]

[Table 2] Next, the water repellency when worn was also evaluated. This evaluation method assumes, for example, wiping a painted surface such as a car body.

A load of 300 g / 2 cm ₂ was applied to a 2 cm × 1 cm wear element to which a Kimwipe was attached, and reciprocated about 700 times on the coated metal plate coated with the water-repellent coating agent of each Example and Comparative Example. After that, tap water was allowed to flow upward, and the contact angle of a water droplet was measured. As the coating wears, the contact angle decreases. That is, as the number of reciprocations of the wear element increases, the contact angle decreases as shown in FIG. It is preferable that the contact angle is 80 degrees or more from the viewpoint of abrasion resistance.

Table 3 shows the contact angles of Examples and Comparative Examples.

[0046]

[Table 3] It was also found that there was a correlation between the contact angle, that is, the water repellency, and the amount of γ-aminopropyltrimethoxysilane added. As shown in FIG. 2, when the added amount of γ-aminopropyltrimethoxysilane was 6.7 parts by weight, the water repellency was significantly improved.

From the above results, it was found that Examples 1 to 3 were superior to Comparative Examples 1 to 6 in water repellency durability.

[0048]

By using the water-repellent coating agent of the present invention, it is possible to impart an excellent appearance and water repellency, particularly water repellency, to the substrate surface without causing abrasion, falling off and the like. Further, since the water-repellent coating agent of the present invention uses a siloxane that does not adversely affect the environment, its practical value is extremely large.

[Brief description of the drawings]

FIG. 1 is a graph showing a relationship between the number of reciprocations of a load and a contact angle.

FIG. 2 is a graph showing the relationship between the amount of aminosilane added and water repellency.

Claims (2)

[Claims] (A) General formula (A) (Wherein, R represents a monovalent organic group or a hydrogen atom;
Represents a hydroxyl group or a hydrolyzable group, and a and b are numbers satisfying the relationship of 0.8 <a <2 and 0.3 ≦ b <2). Part, (B) general formula (Wherein, R ¹ represents a monovalent organic group, Y represents a hydroxyl group or a hydrolyzable group, and c is an integer satisfying 2 ≦ c ≦ 200). Parts by weight, (C) general formula (Wherein m represents an integer of 0 to 9) and / or (Wherein n represents an integer of 3 to 8), 200 to 3000 parts by weight of a volatile polydimethylsiloxane represented by the formula (D):
A water-repellent coating agent containing a curing catalyst and (E) 3 to 15 parts by weight of γ-aminopropyltrimethoxysilane. 2. With respect to 100 parts by weight of the component (A),
The water-repellent coating agent according to claim 1, wherein the water-repellent coating agent comprises 50 to 3100 parts by weight of a diluting solvent (F).