coating agent

Abstract

To provide a coating agent that does not use organic solvents that are harmful to the human body or the global environment, but that forms a coating film that has good gloss, water repellency, and antifouling property even when compared to those produced from conventional products.SOLUTION: Provided is a coating agent that contains polysilazane and cyclic silicone and further contains, optionally, a silicone oil with a terminal functional group being a hydrocarbon.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a coating agent that imparts high film strength, high water repellency, good luster and gloss to metal surfaces and painted surfaces of various industrial products, particularly hard surfaces such as automobile bodies, and also has excellent workability. [Background technology]

[0002] BACKGROUND ART Conventionally, surface protection materials have been applied to hard surfaces such as automobile bodies to impart gloss and luster to the surfaces and protect them. As such a surface protective agent, a coating agent that applies a glassy coating based on polysilazane is used.

[0003] Polysilazane is a type of silane, a compound with reactive groups that chemically bond with silicon, nitrogen, and active hydrogen groups. It reacts with moisture in the air to introduce silyl groups, which condense while generating basic ammonia, forming an amorphous glass coating. Because it is a polymer with a relatively high molecular weight, it must be dissolved in an organic solvent before being used as a glass coating agent.

[0004] Patent Document 1 describes a coating agent containing an organic polysilazane, a curing catalyst, and a reactive silicone oil. This coating agent forms a coating film with excellent quick-drying properties by combining an organic polysilazane with a reactive silicone oil, which has specific properties. However, the organic solvent used for the organic polysilazane is an ester-based solvent, a petroleum-based solvent, or an aliphatic hydrocarbon-based solvent.

[0005] Furthermore, the water-repellent coating agent described in Patent Document 2 contains polysilazane and siloxane resin, and is said to be able to form a coating film with high water repellency, with little adhesion of dirt or deterioration of gloss even under exposure conditions in the natural environment. In this case too, hydrocarbon-based solvents or petroleum-based solvents are used as the organic solvent for polysilazane.

[0006] These conventional technologies use polysilazane as the main agent in the coating agent, but in this case, polysilazane is highly reactive with moisture in the air and reacts with hydroxyl groups to harden rapidly, so water or alcohols cannot be used as solvents.Only petroleum-based solvents such as toluene and xylene, or organic solvents such as ethylbenzene can be used, and these must be used in large quantities. However, organic solvents such as xylene and toluene are known to be harmful to the human body and the global environment, and therefore there has been a demand for coating agents that do not use such organic solvents.

[0007] Furthermore, when such coating agents are used to paint automobile bodies, etc., these organic solvents evaporate in high concentrations, causing serious health problems for automobile manufacturers and workers, and there is also a risk of fire, so it is extremely costly to maintain an appropriate working environment. Furthermore, coating agents containing these organic solvents can damage the substrate to which they are applied, and therefore there has been a demand for the development of coating agents that do not use such organic solvents. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] Patent No. 6420539 [Patent Document 2] Japanese Patent Application Laid-Open No. 2015-137284 Summary of the Invention [Problem to be solved by the invention]

[0009] The present invention was made to solve these problems of the prior art. Its objective is to provide a coating agent that forms a coating film that has better gloss, water repellency, and stain resistance than those produced by conventional products, while not using organic solvents that are harmful to the human body and the global environment. It is also an objective to provide a coating agent that does not cause unnecessary damage to the substrate to which it is applied. [Means for solving the problem]

[0010] In order to solve the above-mentioned problems, the present invention includes the following configurations. [1] A coating agent containing polysilazane and cyclic silicone. [2] The coating agent according to [1], wherein the content of the polysilazane and the content of the cyclic silicone are 0.1 to 50% and 1 to 90%, respectively. [3] The coating agent according to [1] or [2], wherein the cyclic silicone is decamethylcyclopentasiloxane. [4] The coating agent according to any one of [1] to [3], further comprising a silicone oil having a terminal functional group that is a hydrocarbon. [5] The coating agent according to [4], wherein the silicone oil is dimethylpolysiloxane. [6] The coating agent according to [4] or [5], containing 1 to 50% of the silicone oil. [Effects of the Invention]

[0011] In the coating agent of the present invention, since cyclic silicone oil is used as a solvent, there is no risk of harm to human health or fire, and coating can be performed in a healthy environment.In addition, since cyclic silicone oil is biodegradable, even if it is released, it will not have a negative impact on the natural environment, and it will not damage the substrate to be treated. The coating film formed by the coating agent of the present invention has good luster and gloss, and can maintain high water repellency and good antifouling properties for a long period of time, even compared to films formed by conventional coating films. [Brief explanation of the drawings]

[0012] [Figure 1] 1 shows the change in water repellency of a film surface when the coating agent of the present invention is applied to the film. DETAILED DESCRIPTION OF THE INVENTION

[0013] Specific embodiments for carrying out the present invention will be described below. The coating agent of the present invention is composed mainly of polysilazane and cyclic silicone, and may also contain silicone oil having hydrocarbon functional groups at both ends.

[0014] (Polysilazane) The polysilazane used in the coating agent of the present invention is represented by the following general formula (A): JPEG0007737129000001.jpg2870[where, R 1 and R 2 are each independently a hydrogen atom, C 1-6 Alkyl, C 2-6 Alkenyl, C 3-7 represents cycloalkyl, or aryl; R 3 is a hydrogen atom, C 1-6 Alkyl, C 2-6 Alkenyl, C 3-7 Cycloalkyl, aryl, or -(CH2) m -SiR 11 R 12 R 13 and; R 11 , R 12 and R 13 are each independently C 1-6 Alkyl, or C 1-6 is alkoxy; m is an integer selected from 2 to 6; R 1 , R 2 , and R 3 at least one of which is a hydrogen atom] It is a compound having a main skeleton consisting of units represented by the following formula:

[0015] Examples of polysilazanes that can be used in the present invention include R 1 and R 2 are each independently a hydrogen atom or a methyl, and R 3 is a hydrogen atom or tri(C 1-6 Alkoxy)silyl C 2-6 Alkyl, e.g., 3-(triC 1-6 Specific examples of compounds having a main skeleton composed of units represented by formula (A) are (R alkoxysilyl)propyl. 1 , R 2 , R 3 ) is (methyl, hydrogen atom, hydrogen atom), (methyl, methyl, hydrogen atom), (methyl, methyl, methyl), (methyl, methyl, 3-(triethoxysilyl)propyl), (hydrogen atom, methyl, 3-(triethoxysilyl)propyl), etc. The polydisilazanes may be composed of the same repeating unit, or may contain different repeating units.

[0016] The polysilazane used may be one that is soluble in a solvent or that can be uniformly dispersed in a solvent. The number average molecular weight of the polysilazane used is preferably 100 to 50,000, and more preferably 300 to 10,000.

[0017] Polysilazanes generally include those having a chain, cyclic, or crosslinked structure, or those having a plurality of these structures simultaneously within the molecule, and any of these can be used as the polysilazanes. These may be used alone or as a mixture of two or more kinds.

[0018] Polysilazanes are a type of silane that react with moisture in the air to produce silicon dioxide, ammonia, and hydrogen. SiH2NH + 2H2O → SiO2+ NH3+ 2H2(B) Polysilazanes are highly reactive. Therefore, when using polysilazanes alone as the active ingredient in a coating, they cannot be applied uniformly without special techniques (e.g., spray painting, spin coating, etc.). Therefore, it is difficult to apply a coating containing polysilazanes as the only active ingredient uniformly to painted surfaces (painted surfaces) of vehicles (cars, trains, etc.), aircraft fuselages, furniture, building exteriors, and other vehicles with different shapes. In fact, their use may even detract from the aesthetics of the surface. Furthermore, coatings containing polysilazanes alone have low gloss and significantly lose their water repellency due to exposure to ultraviolet light, making them unsuitable for outdoor applications.

[0019] In the present invention, both inorganic polysilazanes (perhydropolysilazanes) and organic polysilazanes having organic groups as substituents can be used. In one embodiment, a mixture of organic polysilazane and inorganic polysilazane can be used, and the weight ratio of organic polysilazane to inorganic polysilazane is, for example, 1:99 to 80:20, more specifically, 20:80 to 80:20. Commercially available polysilazanes can be used. Some commercially available polysilazanes are dissolved in organic solvents, and such solutions can also be used. For example, products with various concentrations under the trade name "Tres Smile" (manufactured by Sanwa Chemical Co., Ltd.) are commercially available as polysilazanes dissolved in organic solvents (polysilazane organic solvent solutions).

[0020] The content of polysilazane is preferably 0.1 to 50% by weight based on the total weight of the coating agent of the present invention. When polysilazane is available as a solution in an organic solvent, the organic solvent can be used as the solvent for the composition by using it as is.

[0021] (cyclic silicone) Cyclic silicones are siloxanes with a ring structure containing dimethylsiloxane units (CH3)2Si-O-, in which a silicon atom (Si) bearing two methyl groups is bonded to an oxygen (O) atom. Common cyclic silicones are abbreviated as D4, D5, and D6, depending on the number of dimethylsiloxane units they contain. D4 is octamethylcyclotetrasiloxane, a silicone oil with a cyclic structure containing four dimethylsiloxane units. Similarly, decamethylcyclopentasiloxane (D5) has five of these units, and dodecamethylcyclohexasiloxane (D6) has six.

[0022] (Decamethylcyclopentasiloxane, D5) These cyclic silicones (low molecular weight dimethylsiloxanes) have a high boiling point but are highly volatile, so they turn into vapor even at room temperature and diffuse into the air. They are also biodegradable, meaning they do not put a burden on the environment. Of these cyclic silicones, it is particularly preferable to use decamethylcyclopentasiloxane (D5) in the present invention, because it is particularly superior to other cyclic silicones in terms of decomposition in the natural environment and its effects on humans and animals. The skeleton of D5 is represented by the following formula (C). JPEG0007737129000002.jpg3459D5 is a volatile liquid at room temperature, but is characterized by its high environmental safety, and is also used as a dry cleaning solvent as an alternative to perchloroethylene. In the present invention, the content of cyclic silicone is preferably 1 to 90%.

[0023] (silicone oil) The coating agent of the present invention can further contain a silicone oil in which the R group at the silicone end is a hydrocarbon. Among silicone oils, which are linear polymers consisting of siloxane bonds, the following three silicone oils, known as straight silicone oils, are particularly preferred: dimethyl silicone oil, methylphenyl silicone oil, and methylhydrogen silicone oil. Among these, dimethyl silicone oil, represented by the following chemical structural formula (D), is particularly preferred. JPEG0007737129000003.jpg2687 In the present invention, it is preferable that the silicone oil is contained in an amount of 1 to 50%.

[0024] (Coating agent manufacturing) Silicone-based coating agents are generally produced by adding a solvent such as an organic solvent into a container, then adding and stirring each type of silicone one by one while checking to see if each is dissolved, and then adding additional UV absorbers, stabilizers, catalysts, etc. The automotive coating agent of the present invention requires the use of a container with a lid and a stirring device, and after making sure the container is dry, work should be carried out at room temperature of 40°C or below while ventilating the work environment.

[0025] The coating agent of the present invention can be blended with various fine powders such as functional silicones, organic solvents as diluents, various catalysts as reaction accelerators, organic, inorganic, or organic-inorganic hybrid powders, etc., as needed, within the scope of not impairing the objects or effects of the present invention. Furthermore, stabilizers, antifreeze agents, rust inhibitors, preservatives, ultraviolet absorbers, pigments, etc. can also be blended with the coating agent of the present invention as needed.

[0026] The coating agent of the present invention can be used by conventional methods, and can be used to treat the surface of the object to be coated (especially a painted surface) by conventional methods such as spraying or application. For example, the most common method is to impregnate a sponge with the coating agent of the present invention, apply it to the painted surface by rubbing, etc., and then wipe it off with a cloth. In addition, methods such as brush application and aerosol spraying can be selected and used depending on the purpose and application. Thereafter, by drying as necessary, it is possible to form a coating on the entire painted surface that has excellent stain resistance, gloss (luster), water repellency, etc. for a long period of time. [Example]

[0027] The present invention will be described in detail below with reference to examples. However, the present invention is not limited to these examples. Note that percentages are expressed by weight unless otherwise specified. In a container with a lid and a stirrer, 15.2 kg of decamethylcyclopentasiloxane (silicone oil TSF405, manufactured by MOMENTIVE) was placed as a cyclic silicone, accounting for 76% of the total mixture. After the lid was placed on the container, nitrogen gas was introduced into the gas phase inside the container and the mixture was stirred. Next, stirring was continued while nitrogen gas was flowing in, and 1.2 kg of perhydropolysilazane (Tresmile NP-110-20, manufactured by Sanwa Chemical Co., Ltd.) was added as polysilazane at a blending amount of 6%, followed by stirring. Furthermore, 3.6 kg of dimethylpolysiloxane (silicone oil KF-96-350CS, manufactured by Shin-Etsu Chemical Co., Ltd.) was added as silicone oil at a blending amount of 18% of the total, and mixed uniformly to finally produce 20 kg of coating agent.

[0028] (characteristic evaluation) The coating agent prepared above was applied to a protection film, and the changes in the surface properties of the protection film due to the application of the coating agent of the present invention were observed.

[0029] (surface condition) The coating agent of the present invention was applied to the surface of a protective film and allowed to dry for one day to harden. As a result, no changes in the surface condition that would occur as a result of damage caused by the solvent were observed on the film surface.

[0030] (Water repellency) After that, the sample was exposed to ultraviolet light for 30 hours in an accelerated light resistance test, and the changes in contact angle and sliding angle were measured before and after the test. The contact angle was evaluated using a 2.5 μL water droplet, and the sliding angle was evaluated using a 50 μL water droplet. A higher contact angle indicates better water repellency, while a lower sliding angle indicates better water droplet sliding. The results are shown in Figure 1. As is clear from Figure 1, it was confirmed that the application of the coating agent of the present invention improved the water-repellent performance of the protection film. In particular, it was revealed that the water-repellent performance was improved when applied twice compared to when applied once, and that the water-repellent effect was maintained even after a 30-hour UV exposure abuse test (equivalent to one week's exposure to sunlight). [Industrial Applicability]

[0031] By using the coating agent of the present invention, it is possible to form a protective coating that can maintain good water repellency and gloss for a long period of time on the painted surfaces of vehicles such as automobiles and trains, and aircraft fuselages.

Claims

1. A coating agent containing 0.1 to 6% polysilazane, 76 to 90% cyclic silicone, and silicone oil with hydrocarbon functional groups at both ends.

2. 2. The coating of claim 1, wherein said cyclic silicone is decamethylcyclopentasiloxane. Antihistamine.

3. 2. The coating agent of claim 1, wherein said silicone oil is dimethylpolysiloxane.

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