JP7519215B2 - Coating composition, coating film, and member provided with coating film - Google Patents

Description

The present invention relates to a coating composition for preventing snow and ice accretion, a coating film, and a member provided with the coating film.

In cryospheres, snow, ice, frost, etc., adhering to the exteriors of automobiles, traffic signals, railways, aircraft, and structures is problematic as it can cause malfunctions or secondary disasters. Deicing agents are commonly used to remove ice and snow from the exteriors of aircraft, for example. However, there are concerns that using large amounts of deicing agents may cause environmental pollution.
One method that has little impact on environmental pollution is to apply a coating to the exterior of an aircraft. This method mainly involves painting fluororesin, silicone resin, urethane resin, etc. on the exterior of an aircraft, which makes it easier to prevent ice and snow buildup and remove ice and snow. However, these coatings cannot maintain their ability to remove ice and snow over the long term, and ice and snow become more likely to build up after about one to two months.

Patent Document 1 discloses an anti-icing and snow-adhering paint composition that is characterized by being composed of a mixture of a chemically reactive silicone rubber, a water-repellent compound, and an organic aqueous solution compound. Here, the chemically reactive silicone rubber has hydroxyl groups, vinyl groups, etc., and is crosslinked with a metal catalyst, peroxide, organic amine, etc. The water-repellent compound is silicone oil, mineral oil, etc. The organic water-soluble compound includes at least one of surfactants (nonionic, anionic, cationic, etc.), polyhydric alcohols (glycerin, ethylene glycol, etc.), and water-soluble resins (PVA resin, hydroxyethyl cellulose, etc.). According to Patent Document 1, the (C) organic water-soluble compound and (B) water-repellent compound of this composition are present on the surface of the (A) chemically reactive silicone rubber coating film, thereby weakening the van der Waals forces and hydrogen bonds that occur between the (A) chemically reactive silicone rubber and snow and ice, making it difficult for snow and ice to adhere to the surface. Furthermore, it is said that the (C) organic water-soluble compound and (B) water-repellent compound, which are also present inside the coating film, seep out to the surface in small amounts, allowing the coating to maintain its snow and ice prevention performance for a long period of time.

Patent Document 2 discloses a surface modifier for glass-based coatings formed on vehicle paint surfaces, which is a water emulsion system with silicone resin as a coating component and dimethyl silicone oil as a coating subcomponent, the silicone resin being a mixture of MQ resin and DT resin, with the mass mixture ratio of the former/the latter being 95/5 to 70/30. According to Patent Document 2, in this composition, the silicone oil contained in the silicone resin coating bleeds out onto the coating surface, removing the silicone oil along with the water, making it difficult for minerals and the like to adhere. This is said to form a coating that maintains excellent water repellency and gloss over the long term and is less susceptible to adhesion.

Patent Document 3 discloses a coating composition that improves the sealing property and dirt adhesion prevention property of rubber members, characterized by containing (A) a specific diorganopolysiloxane with a hydroxyl group at the molecular chain end, (B) a specific organopolysiloxane resin, (C) dimethyl silicone oil, and (D) a condensation catalyst such as a silicon compound having two or more aminoxy groups as an optional component. According to Patent Document 3, when this composition is applied to a rubber member, if the dimethyl silicone oil (C) is present, the composition is promoted to spread wetly and form a smooth coating film. After that, the dimethyl silicone oil (C) is absorbed into the underlying rubber member, and very shallow depressions are formed in the area where the dimethyl silicone oil (C) is absorbed. As a result, many fine and gentle irregularities are formed on the coating film surface, and dirt larger than the irregularities is less likely to adhere because the area of contact with the coating film is reduced. In addition, because the gentle irregularities are fine, when the coating film is sealed with the mating material, it can adhere almost without any gaps, so it has sufficient sealing properties. Furthermore, the presence of (B) silicone resin increases the hardness of the coating film and reduces the adhesion of the coating film surface, making it difficult for dirt to adhere to the coating film. This is said to result in the formation of a coating film that is excellent in preventing dirt adhesion and sealing properties.

Japanese Unexamined Patent Publication No. 62-252477 JP 2014-210240 A JP 2014-148599 A

The (A) chemically reactive silicone rubber and (B) water-repellent compound (silicone oil) used in Patent Document 1 have a high affinity, so the oil tends to remain inside the rubber. As a result, the amount of (B) water-repellent compound (silicone oil) that makes it difficult for ice and snow to adhere to the surface of the coating film is reduced, making it difficult to obtain good ice and snow removal performance. In addition, water-repellent silicone and hydrophilic organic water-soluble resin have low compatibility, so there is a possibility that a high-viscosity mixture will be formed when mixed. High-viscosity liquids do not wet and spread easily when applied, and form surface irregularities. Therefore, there is a problem that in an actual usage environment, if ice and snow adhere to the uneven surface areas, it will be difficult to remove.

In the surface modifier described in Patent Document 2, the resin-based coating has a high crosslink density and there is little physical space in which silicone oil can be retained within the coating. As a result, the amount of silicone oil that can be retained within the coating is small, and the surface deposit removal performance cannot be maintained for a long period of time. In addition, because the resin-based coating is hard and brittle, it is prone to cracks due to the impact of ice particles, sand dust, and the like. If deposits get into the cracks, they become difficult to remove, so there is a problem in that the surface deposit removal performance cannot be maintained for a long period of time.

In the surface modifier described in Patent Document 3, the silicone resin (B) has a tendency to aggregate, which means that aggregates are likely to form within the coating film. If aggregates are present, they appear as large irregularities on the coating film surface, which can lead to problems such as ice and snow getting into the recesses and icing easily forming on the surface.

In view of the above problems, the present invention aims to provide a coating composition, a coating film, and a component provided with a coating film that maintains excellent ice and snow removal performance while being less susceptible to coating film defects.

The present invention encompasses the following:
[1]
(A) a silicone oil having at least two hydroxyl groups in one molecule;
(B) a non-reactive silicone oil; and
(C) a silicone having an aminoxy group;
A coating composition comprising:
[2]
For 100 parts by weight of the silicone oil (A),
0.5 to 200 parts by weight of the non-reactive silicone oil (B),
The coating composition according to [1], characterized in that it contains 7 to 200 parts by weight of the silicone (C) having an aminoxy group.
[3]
The coating composition according to [1] or [2], characterized in that the non-reactive silicone oil (B) contains at least one selected from the group consisting of dimethyl silicone, alkyl-modified silicone, phenyl silicone, and fluorine-modified silicone.
[4]
A coating film obtained from the coating composition according to any one of [1] to [3].
[5]
The coating film according to [4], characterized in that the ice peeling force is less than 80 kPa and the ice peeling force change is less than 110 kPa.
[6]
A member of an automobile body, a peripheral part of an electric automobile battery part, a traffic signal, a railway vehicle, an aircraft body, or an outdoor structure, which is provided with the coating film according to [4] or [5].

The coating film obtained using the coating composition of the present invention is less prone to film damage and maintains excellent ice and snow removal performance.

FIG. 2 is a schematic diagram showing a test method for evaluating ice peeling force.

The coating composition according to the present invention comprises:
(A) a silicone oil having at least two hydroxyl groups in one molecule;
(B) a non-reactive silicone oil; and
(C) a silicone having an aminoxy group;
The present invention is characterized in that it includes the following.

[(A) Silicone oil having at least two hydroxyl groups per molecule]
(A) Silicone oils having at least two or more hydroxyl groups per molecule are specifically exemplified by dimethyl silicone diol, dimethyl diphenyl silicone diol, and methyl phenyl silicone diol, in which the molecular chain terminal of dimethyl silicone oil has a hydroxyl group, and modified silicone oils such as alkyd-modified silicone, polyester-modified silicone, acrylic-modified silicone, epoxy-modified silicone, phenol-modified silicone, urethane-modified silicone, fluorine-modified silicone, silica-modified silicone, vinyl-modified silicone, and amino-modified silicone, in which a portion of dimethyl silicone oil is modified with a functional group other than a hydroxyl group. Any one or more of these can be appropriately selected and used in the present invention.
The position of the hydroxyl group in the molecule is not particularly limited. For example, the hydroxyl group may be attached to both ends of a linear molecule.

Silicone oil having at least two or more hydroxyl groups in one molecule is usually mixed with a curing agent (silicone having an aminoxy group (C) in the present invention) and then applied, but when the viscosity is high, it is difficult to spread wetly, and uneven application causes surface unevenness in the coating film after curing, making it easy to ice. Furthermore, the convex parts of the surface unevenness caused by uneven application also occur in the coating film after curing, so the coating film is easily damaged or worn due to collision with ice particles, etc., and is easy to ice. In addition, when the viscosity is low, the distance between multiple hydroxyl groups in one molecule becomes short, and a brittle coating film with a short distance between crosslinking points is formed after curing, so film damage is easy to occur and ice is easy to adhere to the damaged parts. Therefore, it is necessary to select a silicone oil having at least two or more hydroxyl groups in one molecule with an appropriate viscosity. For example, the viscosity at 25° C. is preferably 1 cSt or more, more preferably 50 cSt or more, even more preferably 100 cSt or more, and is preferably 400,000 cSt or less, more preferably 200,000 cSt or less, even more preferably 100,000 cSt or less. Here, 1 cSt is 1 mm ² /s.

Commercially available silicone oils with at least two hydroxyl groups per molecule include YF3800, YF3905, YF3057, and YF3802 (all manufactured by Momentive Performance Materials Japan LLC), BY16-201, and SF8427 Fluid (all manufactured by Dow Toray Industries, Inc.), and KF-6002 and KF-6003 (all manufactured by Shin-Etsu Chemical Co., Ltd.).

[(B) Non-reactive silicone oil]
Specific examples of the non-reactive silicone oil (B) include dimethyl silicone, alkyl-modified silicone, phenyl silicone, fluorine-modified silicone oil, etc. Among these, any one or more of them can be appropriately selected and used in the present invention.

The non-reactive silicone oil (B) is different from the silicone oil (A) described above. Specifically, it does not contain reactive functional groups (hydroxyl groups, vinyl groups, aminoxy groups, etc.) in its molecular structure. Preferably, the non-reactive silicone oil (B) is blended in a ratio of 0.5 to 200 parts by weight per 100 parts by weight of the silicone oil (A).

In the present invention, the non-reactive silicone oil bleeds out onto the coating film surface, so that even if ice and snow form on the coating film surface, the ice and snow are easily peeled off. However, if the viscosity of the non-reactive silicone oil is high, the amount of bleed out onto the coating film surface is small, and if ice and snow form on the coating film surface, the ice and snow are not easily peeled off. Furthermore, if the viscosity is high, it is difficult for the oil to spread during application, and surface irregularities due to uneven application occur, making it easier for ice to form on the coating film surface. Therefore, it is preferable to select a non-reactive silicone oil with a low viscosity. Specifically, the viscosity at 25°C is preferably 1,000,000 cSt or less, more preferably 100,000 cSt, and even more preferably 10,000 cSt or less.

Non-reactive silicone oils available on the market include KF-96-1,000CS, KF-96-5,000CS, KF-4701, KF-54, FL-100-450CS (all manufactured by Shin-Etsu Chemical Co., Ltd.), Element14 PDMS200, Element14 PDMS500 (all manufactured by Momentive Performance Materials Japan, LLC), SF8416Fluid, and 56Additive (all manufactured by Dow Toray Co., Ltd.).

[(C) Silicone having an aminoxy group]
As the silicone having an aminoxy group (C), an aminoxy group-containing silicone of the following formula (1) can be used.

In the above formula (1), ^R1 is a siloxane structure, and ^R2 and ^R3 each independently represent the same or different alkyl group. The alkyl group is a linear, branched, or cyclic saturated or unsaturated hydrocarbon group. The alkyl group preferably has 1 to 12 carbon atoms, and more preferably has 1 to 6 carbon atoms. Specifically, a methyl group, an ethyl group, a propyl group, or the like can be used.

(C) Silicone having an aminoxy group is different from both the silicone oil (A) and the silicone oil (B). Specifically, it is different from the silicone oil (A) because it does not contain a hydroxyl group in its molecular structure. Also, (C) silicone having an aminoxy group is different from the silicone oil (B) because it contains an aminoxy group as a reactive functional group in its molecular structure. Preferably, (C) silicone having an aminoxy group is blended in a ratio of 7 to 200 parts by weight per 100 parts by weight of the silicone oil (A).

Commercially available silicone curing agents containing an aminoxy group include Sealant 70B and Sealant 74B (both manufactured by Shin-Etsu Chemical Co., Ltd.) and ME35(B) (manufactured by Momentive Performance Materials Japan, LLC).

[Coating film]
There is no particular limitation on the method for forming the coating film of the present invention, but it is preferable to apply the coating composition of the present invention to members made of various materials by a general method, and then dry and cure the applied composition.

The materials that can be coated include, but are not limited to, metals (stainless steel, SPCC, aluminum, nickel, etc.), resins (urethane, epoxy, silicone resin, polyolefin, polycarbonate, polypropylene, polyamide, polyimide, polyamideimide, etc.), ceramics (silicon carbide, alumina, etc.), glass, and rubber (natural rubber, EPDM, silicone rubber, fluororubber, etc.).

There are no particular limitations on the coating method, but examples include bar coating, roll coating, screen coating, flexography, spin coating, dip coating, spray coating, and slide coating.

The coating composition according to the present invention can be cured by leaving it in the air at room temperature for a predetermined time after application. If necessary, it can be heated or placed under reduced pressure. When heating, the heating temperature is not particularly limited, and is, for example, 50°C or more and 180°C or less. The heating time is also not particularly limited, and is, for example, 30 seconds or more and 60 minutes or less. If necessary, the curing may be promoted by irradiating with light, preferably ultraviolet light. When irradiating with light, the irradiation amount is not particularly limited, and is, for example, 100 mJ/ ^cm2 or more and 1000 mJ/ ^cm2 or less.

The thickness of the coating film according to the present invention after curing is not particularly limited, but is preferably 1 μm or more, more preferably 3 μm or more, even more preferably 5 μm or more, and is preferably 50 μm or less, more preferably 20 μm or less, even more preferably 15 μm or less.

The coating film of the present invention thus obtained has an ice release force of less than 80 kPa and an ice release force change of less than 110 kPa. The method of determining the ice release force, continuous ice release force, and ice release force change will be described later.

The coating film of the present invention may be overcoated with (B) non-reactive silicone oil. This allows the ice and snow removal performance to be maintained for an even longer period of time. As long as (B) non-reactive silicone oil can be used in the present invention, there are no restrictions on the application method or the presence or absence of dilution, and any one or more types of oil may be selected and used as appropriate.

Although not wishing to be bound by theory, the mechanism by which the advantageous effects of the present invention are obtained is believed to be as follows.
Generally, as one of the methods for obtaining a silicone coating film, (A) silicone oil having at least two or more hydroxyl groups in one molecule is mixed with (C) silicone having an aminoxy group as a hardening agent to form a silicone coating film, and this film is hardened to obtain a silicone coating film.Since (C) silicone having an aminoxy group is relatively easy to be compatible with water and ice, the less silicone having an aminoxy group (C) is used, the more silicone components that are less compatible with water and ice will be present in the silicone coating film, and this is considered to be preferable from the viewpoint of preventing snow and ice from being attached and water repellency.
However, in a silicone coating film containing (B) non-reactive silicone oil, by blending a large amount of (C) silicone having an aminoxy group, which has a high affinity with water and ice, the (B) non-reactive silicone oil cannot be retained inside the silicone coating film and leaks out (bleeds out). In this way, the (B) non-reactive silicone oil present on the surface of the coating film is peeled off together with the ice and snow, and excellent ice and snow prevention performance can be achieved. In the present invention, by blending a large amount of (C) silicone having an aminoxy group as a hardener for the silicone coating film, the (B) non-reactive silicone oil is likely to bleed out. This is because the (B) non-reactive silicone oil is lipophilic, while the (C) cured silicone having an aminoxy group is oil-repellent, and therefore has low compatibility. The (B) non-reactive silicone oil bleeds out to the surface of the coating film in a form separated from the (C) cured silicone having an aminoxy group, and therefore excellent ice and snow prevention performance is achieved.
In addition, during the process of curing the coating film, the aminoxy group contained in the silicone having an aminoxy group (C) is eliminated and remains as an amine-based liquid compound. This amine-based liquid compound is poorly compatible with the silicone coating film and therefore tends to bleed out onto the coating film surface. The amine-based liquid compound peels off together with the icing and snow, thereby providing excellent icing and snow prevention performance.
In addition, the silicone coating film containing a large amount of silicone having an aminoxy group (C) has a lower crosslink density than the glass-based coating film. This allows the film to have a large amount of physical space for holding the non-reactive silicone oil (B), so that it can hold a relatively large amount of the non-reactive silicone oil (B). Since a large amount of the non-reactive silicone oil (B) is held, the non-reactive silicone oil (B) continues to bleed out on the surface of the coating film for a long time, so that the anti-icing and snow-adhesion performance can be maintained for a long time.
Furthermore, the silicone coating film containing a large amount of silicone having an aminoxy group (C) has a lower crosslink density than the glass-based coating film, and therefore has excellent flexibility. Therefore, the flexible coating film absorbs the impact of ice particles and sand dust, making it less likely to crack, and ice and snow are less likely to get into the cracks and form ice and snow, which can prevent ice and snow from forming.

[Members with coating film]
The coating film according to the present invention maintains excellent icing and snow removal performance even after being exposed to harsh environments for a long period of time, and is resistant to coating film damage, and is therefore particularly suitable for application to components such as automobile bodies, electric vehicle battery component peripheries, traffic signals, railway vehicles, aircraft bodies, outdoor structures (exterior walls of buildings, road signs, etc.), etc.

For the purpose of adhesion to the member, a primer layer may be provided between the member and the coating film of the present invention. In addition, if the member has a coating film other than that of the present invention (e.g., for the purpose of coloring or scratch prevention, etc.), the coating composition of the present invention may be applied on top to form a two-layer coating film.

(Preparation of Coating Composition)
The components were mixed in the ratios shown in Table 1 to obtain coating compositions of Examples 1 to 29 and Comparative Examples 1 to 7. The values shown in Table 1 represent parts by weight.

(Preparation of coating film)
The coating compositions of Examples 1 to 29 and Comparative Examples 1 to 7 shown in Table 1 were spray-coated onto a 3 mm-thick SUS304 plate to a film thickness of 10±3 μm, and the plate was left to stand at room temperature for 24 hours or more to obtain a coating film.

[Evaluation method]
(Ice peeling force)
The ice peeling force was evaluated using a push-pull gauge (Imada Corporation, model number PSM-20N). A cylinder (made of SUS304) with an inner diameter of 20 mm and an outer diameter of 25.6 mm was placed on the coating film, and 3.6 g of ion-exchanged water was filled into the cylinder, which was then left to stand at -15°C for 1 hour in a thermostatic chamber (Espec Corporation) to form ice (Figure 1). The maximum peeling force when the formed ice was peeled off together with the cylinder in a direction parallel to the coating film using the push-pull gauge was taken as the ice peeling force.

(Continuous ice peeling force)
The ice was peeled off in the same manner as in the ice peeling strength evaluation, and then ice was formed in the same location and peeled off. The peeling strength of the fifth ice peeling attempt was regarded as the continuous ice peeling strength.
In a real environment, for example, ice and snow that has adhered to the exterior surface of a building or an automobile may be removed by wind, vibration, or other artificial means. However, snowfall and blizzards occur intermittently in winter, so ice and snow will adhere to the surface from which the ice and snow was removed again. In other words, it is preferable for the coating film of the present invention to continuously exhibit ice and snow peeling performance. In the present invention, the evaluation of the continuous ice peeling force is used as an index of the degree to which ice peeling performance is maintained.

(Changes in ice peeling force)
The value obtained from the following calculation formula 1 was regarded as the change in ice peeling force.

(Wear volume)
A wrapping film sheet #400 (manufactured by TRUSCO NAKAYAMA CORPORATION) was attached to a reciprocating friction force measuring instrument (manufactured by Trinity Lab Co., Ltd.), and the coating film was abraded at a sliding speed of 100 mm/sec, a vertical load of 500 g, and 20 reciprocating motions, and the abrasion volume was evaluated.

(viscosity)
The viscosity was measured using a rotational viscometer (manufactured by Malvern Panalytical Co.) at 25±1° C. and 60 rpm, and the value measured 1 minute after the start of measurement was adopted.

(Surface roughness Ra)
The values were measured using a laser microscope (manufactured by Olympus Corporation) at a magnification of 1056 times.

(Surface roughness Ra after continuous ice removal)
The surface roughness of the peeling marks after the continuous ice peeling test was measured in the same manner as in the evaluation of the surface roughness Ra.

Example 1
(B) non-reactive silicone oil [dimethyl silicone] (KF-96-1,000CS manufactured by Shin-Etsu Chemical Co., Ltd.) was added to (A) silicone oil having at least two or more hydroxyl groups in one molecule (YF3057 manufactured by Momentive Performance Materials Japan, LLC), and then toluene (manufactured by Kanto Chemical Co., Ltd.) was added to a solid content of 20% by weight, and the mixture was stirred for 30 minutes with a ball mill. After stirring, (C) silicone having an aminoxy group (ME35 (B) manufactured by Momentive Performance Materials Japan, LLC) was added, and the mixture was stirred for 10 minutes with a ball mill to obtain a coating composition. At this time, the amount of addition was adjusted so that 0.5 parts by weight of (B) non-reactive silicone oil and 10 parts by weight of (C) silicone having an aminoxy group were added to 100 parts by weight of (A) silicone oil having at least two or more hydroxyl groups in one molecule.

Example 2
Using the same procedure as in Example 1, the amounts of (B) non-reactive silicone oil and (C) silicone having an aminoxy group were adjusted to 5 parts by weight and 10 parts by weight, respectively, per 100 parts by weight of (A) silicone oil having at least two or more hydroxyl groups in one molecule, to obtain a coating composition.

Example 3
Using the same procedure as in Example 1, the amounts of (B) non-reactive silicone oil and (C) silicone having an aminoxy group were adjusted to 10 parts by weight per 100 parts by weight of (A) silicone oil having at least two or more hydroxyl groups in one molecule, to obtain a coating composition.

Example 4
Using the same procedure as in Example 1, the amounts of (B) non-reactive silicone oil and (C) silicone having an aminoxy group were adjusted to 30 parts by weight and 10 parts by weight, respectively, with respect to 100 parts by weight of (A) silicone oil having at least two or more hydroxyl groups in one molecule, to obtain a coating composition.

Example 5
Using the same procedure as in Example 1, the amounts of (B) non-reactive silicone oil and (C) silicone having an aminoxy group were adjusted to 50 parts by weight and 10 parts by weight, respectively, with respect to 100 parts by weight of (A) silicone oil having at least two or more hydroxyl groups in one molecule, to obtain a coating composition.

Example 6
Using the same procedure as in Example 1, the amounts of (B) non-reactive silicone oil and (C) silicone having an aminoxy group were adjusted to 10 parts by weight per 100 parts by weight of (A) silicone oil having at least two or more hydroxyl groups in one molecule, to obtain a coating composition.

Example 7
Using the same procedure as in Example 1, the amounts of (B) non-reactive silicone oil and (C) silicone having an aminoxy group were adjusted to 150 parts by weight and 10 parts by weight, respectively, with respect to 100 parts by weight of (A) silicone oil having at least two or more hydroxyl groups in one molecule, to obtain a coating composition.

Example 8
Using the same procedure as in Example 1, the amounts of (B) non-reactive silicone oil and (C) silicone having an aminoxy group were adjusted to 200 parts by weight and 10 parts by weight, respectively, with respect to 100 parts by weight of (A) silicone oil having at least two or more hydroxyl groups in one molecule, to obtain a coating composition.

<Example 9>
Using the same procedure as in Example 1, the amounts of (B) non-reactive silicone oil and (C) silicone having an aminoxy group were adjusted to 50 parts by weight and 7 parts by weight, respectively, with respect to 100 parts by weight of (A) silicone oil having at least two or more hydroxyl groups in one molecule, to obtain a coating composition.

Example 10
Using the same procedure as in Example 1, the amounts of (B) non-reactive silicone oil and (C) silicone having an aminoxy group were adjusted to 50 parts by weight and 15 parts by weight, respectively, with respect to 100 parts by weight of (A) silicone oil having at least two or more hydroxyl groups in one molecule, to obtain a coating composition.

Example 11
Using the same procedure as in Example 1, the amounts of (B) non-reactive silicone oil and (C) silicone having an aminoxy group were adjusted to 50 parts by weight and 25 parts by weight, respectively, based on 100 parts by weight of (A) silicone oil having at least two or more hydroxyl groups in one molecule, to obtain a coating composition.

Example 12
Using the same procedure as in Example 1, the amounts of (B) non-reactive silicone oil and (C) silicone having an aminoxy group were adjusted to 50 parts by weight per 100 parts by weight of (A) silicone oil having at least two or more hydroxyl groups in one molecule, to obtain a coating composition.

Example 13
Using the same procedure as in Example 1, the amounts of (B) non-reactive silicone oil and (C) silicone having an aminoxy group were adjusted to 50 parts by weight and 100 parts by weight, respectively, for (A) 100 parts by weight of silicone oil having at least two or more hydroxyl groups in one molecule, to obtain a coating composition.

<Example 14>
Using the same procedure as in Example 1, the amounts of (B) non-reactive silicone oil and (C) silicone having an aminoxy group were adjusted to 50 parts by weight and 150 parts by weight, respectively, with respect to 100 parts by weight of (A) silicone oil having at least two or more hydroxyl groups in one molecule, to obtain a coating composition.

Example 15
Using the same procedure as in Example 1, the amounts of (B) non-reactive silicone oil and (C) silicone having an aminoxy group were adjusted to 50 parts by weight and 200 parts by weight, respectively, with respect to 100 parts by weight of (A) silicone oil having at least two or more hydroxyl groups in one molecule, to obtain a coating composition.

<Example 16>
A coating composition was obtained in the same manner as in Example 5, except that the (B) non-reactive silicone oil [dimethyl silicone] in Example 5 was replaced with an alkyl-modified silicone (KF-4701 manufactured by Shin-Etsu Chemical Co., Ltd.).

<Example 17>
A coating composition was obtained in the same manner as in Example 5, except that the (B) non-reactive silicone oil [dimethyl silicone] in Example 5 was replaced with phenyl silicone (KF-54 manufactured by Shin-Etsu Chemical Co., Ltd.).

<Example 18>
A coating composition was obtained in the same manner as in Example 5, except that the (B) non-reactive silicone oil [dimethyl silicone] in Example 5 was replaced with a fluorine-modified silicone (FL-100-450CS manufactured by Shin-Etsu Chemical Co., Ltd.).

<Example 19>
A coating composition was obtained in the same manner as in Example 5, except that the silicone oil having at least two hydroxyl groups per molecule (A) was replaced with one having a viscosity of 400,000 cst.

<Example 20>
A coating composition was obtained in the same manner as in Example 5, except that the silicone oil having at least two hydroxyl groups per molecule (A) was replaced with one having a viscosity of 300,000 cst.

<Example 21>
A coating composition was obtained in the same manner as in Example 5, except that the silicone oil having at least two hydroxyl groups per molecule (A) was replaced with one having a viscosity of 200,000 cst.

<Example 22>
A coating composition was obtained in the same manner as in Example 5, except that the silicone oil having at least two hydroxyl groups per molecule (A) was replaced with one having a viscosity of 100,000 cst.

<Example 23>
A coating composition was obtained in the same manner as in Example 5, except that the silicone oil having at least two hydroxyl groups per molecule (A) was replaced with one having a viscosity of 100 cst.

<Example 24>
A coating composition was obtained in the same manner as in Example 5, except that the silicone oil having at least two hydroxyl groups per molecule (A) was replaced with one having a viscosity of 50 cst.

<Example 25>
A coating composition was obtained in the same manner as in Example 5, except that the silicone oil having at least two hydroxyl groups per molecule (A) was replaced with one having a viscosity of 30 cst.

<Example 26>
A coating composition was obtained in the same manner as in Example 5, except that the silicone oil (A) having at least two hydroxyl groups per molecule was replaced with one having a viscosity of 1 cst.

<Example 27>
A coating composition was obtained in the same manner as in Example 5, except that the (B) non-reactive silicone oil [dimethyl silicone] in Example 5 was replaced with one having a viscosity of 1,000,000 cst (KF-96H-1,000,000 CS, manufactured by Shin-Etsu Chemical Co., Ltd.).

<Example 28>
A coating composition was obtained in the same manner as in Example 5, except that the (B) non-reactive silicone oil [dimethyl silicone] in Example 5 was replaced with one having a viscosity of 100,000 cst (KF-96H-100,000 CS manufactured by Shin-Etsu Chemical Co., Ltd.).

<Example 29>
A coating composition was obtained in the same manner as in Example 5, except that the (B) non-reactive silicone oil [dimethyl silicone] in Example 5 was replaced with one having a viscosity of 10,000 cst (KF-96H-10,000 CS manufactured by Shin-Etsu Chemical Co., Ltd.).

<Comparative Example 1>
Using the same procedure as in Example 1, the amounts of (B) non-reactive silicone oil and (C) silicone having an aminoxy group were adjusted to 0.1 part by weight and 10 parts by weight, respectively, for 100 parts by weight of (A) silicone oil having at least two or more hydroxyl groups in one molecule, to obtain a coating composition.

<Comparative Example 2>
Using the same procedure as in Example 1, the amounts of (B) non-reactive silicone oil and (C) silicone having an aminoxy group were adjusted to 300 parts by weight and 10 parts by weight, respectively, with respect to 100 parts by weight of (A) silicone oil having at least two or more hydroxyl groups in one molecule, to obtain a coating composition.

<Comparative Example 3>
Using the same procedure as in Example 1, the amounts of (B) non-reactive silicone oil and (C) silicone having an aminoxy group were adjusted to 10 parts by weight per 100 parts by weight of (A) silicone oil having at least two or more hydroxyl groups in one molecule, to obtain a coating composition.

<Comparative Example 4>
Using the same procedure as in Example 1, the amounts of (B) non-reactive silicone oil and (C) silicone having an aminoxy group were adjusted to 100 parts by weight of (A) silicone oil having at least two or more hydroxyl groups in one molecule, and 300 parts by weight of the silicone oil were added to obtain a coating composition.

<Comparative Example 5>
A coating composition was obtained in the same manner as in Example 5, except that (C) the silicone having an aminoxy group was replaced with (E) a metal catalyst (titanium-based polymerization catalyst, DX-175 manufactured by Shin-Etsu Chemical Co., Ltd.).

<Comparative Example 6>
A coating composition was obtained in the same manner as in Example 5, except that (A) silicone oil having at least two hydroxyl groups per molecule was replaced with (D) silicone resin (XC-96-B0446, manufactured by Momentive Performance Materials Japan, LLC).

<Comparative Example 7>
In Example 5, 100 parts by weight of (A) silicone oil having at least two or more hydroxyl groups per molecule was replaced with 50 parts by weight of (A) silicone oil having at least two or more hydroxyl groups per molecule and 50 parts by weight of (D) silicone resin (XC-96-B0446 manufactured by Momentive Performance Materials Japan, LLC), and a coating composition was obtained in the same manner.

[Evaluation results]
The compositions and physical properties of the examples and comparative examples are summarized in Tables 1A to 1D.
From Examples 1 to 8 and Comparative Examples 1 and 2, it can be seen that when the amount of (B) non-reactive silicone oil is less than 0.5 parts by weight (Comparative Example 1), the amount of (B) non-reactive silicone oil required for ice peeling is insufficient, so the ice peeling force, continuous ice peeling force, and ice peeling force change are large. In addition, when the amount of (B) non-reactive silicone oil present on the coating film surface is too small, the effect of reducing the frictional resistance force due to liquid lubrication is reduced, and the frictional resistance force of the coating film surface increases, so the coating film is easily scraped during sliding. This shows that the wear volume is large. Conversely, when the amount of (B) non-reactive silicone oil is more than 200 parts by weight (Comparative Example 2), it can be seen that the wear volume is large because the excess (B) non-reactive silicone oil reduces the strength of the coating film. Furthermore, if the coating film strength is low, the coating film is peeled off at the same time when the ice is peeled off, causing unevenness on the film surface. It can be seen that the continuous ice peeling force is large because the second and subsequent ice is difficult to peel off due to the anchor effect.

Also, as can be seen from Table 1, in order to obtain good ice-release power, the amount of (B) non-reactive silicone oil is more preferably 5 parts by weight or more, and even more preferably 10 parts by weight or more.

To obtain good continuous ice release power, the amount of (B) non-reactive silicone oil is more preferably 5 to 150 parts by weight, and even more preferably 30 to 100 parts by weight.

To obtain good ice release force change, the amount of non-reactive silicone oil (B) is more preferably 5 to 150 parts by weight, and even more preferably 30 to 100 parts by weight.

To obtain a good wear volume, the amount of (B) non-reactive silicone oil is more preferably 150 parts by weight or less, and even more preferably 100 parts by weight or less.

From Examples 9 to 15 and Comparative Examples 3 and 4, it can be seen that when the amount of silicone having an aminoxy group (C) is less than 7 parts by weight (Comparative Example 3), the amount of non-reactive silicone oil (B) that bleeds out onto the coating film surface is small, and the value of the continuous ice peeling force is large. It can also be seen that the wear volume is large because a coating film with a low crosslink density is formed and is soft. Conversely, when the amount of silicone having an aminoxy group (C) is more than 200 parts by weight (Comparative Example 4), it can be seen that the wear volume is large because the excess silicone having an aminoxy group (C) forms a brittle coating film. Furthermore, a brittle coating film causes the paint film to peel off at the same time as the ice peels off, resulting in unevenness on the coating film surface. It can also be seen that the continuous ice peeling force is large because the second and subsequent ice is difficult to peel off due to the anchor effect.

Also, as can be seen from Table 1, in order to obtain good ice release power, it is more preferable that the amount of silicone having an aminoxy group (C) is 10 parts by weight or more, and even more preferably 25 parts by weight or more.

To obtain good continuous ice release power, the amount of silicone having an aminoxy group (C) is more preferably 10 to 150 parts by weight, and even more preferably 25 to 100 parts by weight.

To obtain good ice release force change, the amount of silicone having an aminoxy group (C) is more preferably 10 to 150 parts by weight, and even more preferably 25 to 100 parts by weight.

To obtain a good wear volume, the amount of silicone having an aminoxy group (C) is more preferably 150 parts by weight or less, and even more preferably 100 parts by weight or less.

From Example 5 and Examples 16 to 18, it can be seen that even when the type of (B) non-reactive silicone oil is changed, the viscosity is low, the wear volume is small, and the ice release force, continuous ice release force, and change in ice release force are small.

From Examples 19 to 26, it can be seen that even when the viscosity of (A) silicone oil having at least two hydroxyl groups per molecule is changed, the viscosity is low, the wear volume is small, and the ice release force, continuous ice release force, and change in ice release force are small.

When a silicone oil having at least two hydroxyl groups per molecule (A) with high viscosity is used, the coating composition of the present invention has a high viscosity, which makes it difficult for the coating composition to spread when applied, and is prone to surface irregularities. Ice formation on the surface irregularities tends to increase the ice peeling force, continuous ice peeling force, and change in ice peeling force. In addition, the surface protrusions tend to be easily worn due to stress concentration during sliding, so the wear volume tends to be large. Furthermore, if the wear volume is large, the film surface protrusions will peel off together with the ice and snow during continuous ice peeling, leaving peeling marks, and the surface roughness after continuous ice peeling is likely to be large.

Conversely, when a silicone oil with low viscosity (A) and at least two hydroxyl groups per molecule is used, it tends to form a brittle film with a high cross-linking density. When ice and snow are peeled off, the film comes off together with the ice, which can increase the ice peeling force in combination with the force of the film peeling off. Surface irregularities are created in the area where the film has peeled off, which increases the continuous ice peeling force, the change in ice peeling force, and the surface roughness after continuous ice peeling, and the wear volume is also likely to increase.

Also, as can be seen from Table 1, in order to obtain good ice-release power, it is more preferable that the viscosity of (A) the silicone oil having at least two hydroxyl groups per molecule is 50 to 200,000 cSt, and even more preferably 100 to 100,000 cSt.

To obtain good continuous ice-release power, it is more preferable that (A) the silicone oil having at least two hydroxyl groups per molecule has a viscosity of 50 to 200,000 cSt, and even more preferably 100 to 100,000 cSt.

To obtain a good change in ice release force, it is more preferable that the viscosity of (A) the silicone oil having at least two hydroxyl groups per molecule is 50 to 200,000 cSt, and even more preferably 100 to 100,000 cSt.

To obtain a good wear volume, it is more preferable that (A) the silicone oil having at least two hydroxyl groups per molecule has a viscosity of 30 to 300,000 cSt, and even more preferably 50 to 200,000 cSt.

To obtain a good viscosity, it is more preferable that the viscosity of (A) the silicone oil having at least two hydroxyl groups per molecule is 300,000 cSt or less, and even more preferable that it is 100,000 cSt or less.

To obtain a good surface roughness Ra, it is more preferable that the viscosity of (A) the silicone oil having at least two hydroxyl groups per molecule is 300,000 cSt or less, and even more preferably 100,000 cSt or less.

To obtain a good surface roughness Ra after continuous ice removal, it is more preferable that (A) the viscosity of the silicone oil having at least two hydroxyl groups per molecule is 30 to 300,000 cSt, and even more preferably 50 to 100,000 cSt or less.

In the coating composition of the present invention, by selecting a silicone oil (A) having at least two hydroxyl groups per molecule and with an appropriate viscosity according to the characteristics required for the material to which it is applied (e.g., exterior material), it is possible to control the viscosity of the entire coating composition, and thus to form a coating film with characteristics suited to the material.

From Examples 27 to 29, it can be seen that even when the viscosity of (B) non-reactive silicone oil is changed, the viscosity is low, the wear volume is small, and the ice release force, continuous ice release force, and change in ice release force are small.

When a non-reactive silicone oil (B) with high viscosity is used, it is difficult to bleed out from within the coating film, and the ice peeling force, continuous ice peeling force, and change in ice peeling force are likely to be large. In addition, due to the high viscosity of the coating composition in the present invention, it is difficult to wet and spread during application, and unevenness is likely to occur on the surface of the coating film formed by hardening the applied film. In particular, the surface protrusions are easily worn due to stress concentration during sliding, so the wear volume tends to be large. Furthermore, if the wear volume is large, the film surface protrusions will peel off together with the ice and snow during continuous ice peeling, leaving peeling marks, and the surface roughness after continuous ice peeling is likely to be large.

Also, as can be seen from Table 1, in order to obtain good ice release force, continuous ice release force, ice release force change, wear volume, surface roughness, and surface roughness after continuous ice release, it is more preferable that the viscosity of (B) the non-reactive silicone oil is 100,000 cSt or less, and even more preferably 10,000 cSt or less.

From Example 5 and Comparative Example 5, when (C) silicone having an aminoxy group is replaced with (E) metal catalyst, the cured coating film formed from (A) silicone oil having at least two or more hydroxyl groups in one molecule and (E) metal catalyst has a high affinity with (B) non-reactive silicone oil, so (B) non-reactive silicone oil is less likely to bleed out onto the coating film surface. This leads to larger ice release force, continuous ice release force, and ice release force change.

From Example 5 and Comparative Example 6, when (A) silicone oil having at least two hydroxyl groups per molecule is replaced with (D) silicone resin, the coating film formed from (D) silicone resin has a high crosslink density, and (B) non-reactive silicone oil cannot be retained in the coating film for a long period of time, so oil shortages are likely to occur when ice is continuously peeled off. Therefore, it can be seen that the force for peeling off continuous ice is large. Furthermore, it can be seen that the coating film formed from (D) silicone resin is prone to forming a brittle film, so the wear volume is large.

From Example 5 and Comparative Example 7, when a portion of (A) silicone oil having at least two or more hydroxyl groups per molecule is replaced with (D) silicone resin, the silicone resin (D) tends to aggregate easily, resulting in an uneven shape on the film surface. It can be seen that when ice forms on the unevenness of the film surface, it becomes difficult to peel off due to the anchor effect, resulting in a large ice peeling force and continuous ice peeling force. Furthermore, it can be seen that the formed film surface convex parts are easily scraped off due to stress concentration during sliding, resulting in a large wear volume.

The present invention provides a coating composition that maintains excellent icing and snow removal performance while forming a coating film on a material that is less likely to cause film damage.

Claims (6)

(A) a silicone oil having at least two hydroxyl groups in one molecule, no reactive functional groups other than hydroxyl groups, curing at room temperature, and a viscosity at 25° C. of 1 cSt or more and 400,000 cSt or less, per 100 parts by weight of the silicone oil,
(B) 0.5 parts by weight or more and 200 parts by weight or less of a non-reactive silicone oil having a viscosity of 450 cSt or more and 1,000,000 cSt or less at 25°C,
(C) 7 parts by weight or more and 200 parts by weight or less of a silicone having an aminoxy group and not containing a hydroxyl group,
and is free of silicone resin. 2. The coating composition according to claim 1, wherein the silicone oil (A) is one or more selected from the group consisting of dimethyl silicone diol, dimethyl diphenyl silicone diol, and methyl phenyl silicone diol, each of which has a hydroxyl group at its molecular chain terminal . 3. The coating composition according to claim 1, wherein the non-reactive silicone oil (B) comprises at least one selected from the group consisting of dimethyl silicone, alkyl-modified silicone, phenyl silicone, and fluorine-modified silicone. A coating film obtained from the coating composition according to any one of claims 1 to 3. 5. The coating film according to claim 4, wherein the ice release force is less than 80 kPa and the ice release force change is less than 110 kPa. 6. A member of an automobile body, a peripheral part of an electric automobile battery part, a traffic signal, a railway vehicle, an aircraft body, or an outdoor structure, which is provided with the coating film according to claim 4 or 5.