JP2010013523A - Method and coating composition for recovering transparency of transparent resin member - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for recovering transparency, which is directed at recovering the transparency, deteriorated over time, of a transparent resin member, and at maintaining the transparency for a long term; and to provide a coating composition which is used for recovering the transparency of the transparent resin member. <P>SOLUTION: The method for recovering the transparency of the transparent resin member includes: a pretreatment step of pretreating the surface of the transparent resin member, deteriorated in transparency over time, with a pretreatment agent; and an application step of applying the coating composition for recovering the transparency of the transparent resin member to the surface to be treated of the pretreated transparent resin member, wherein the coating composition that contains: a moisture-hardenable silicone resin or oligomer; a curing catalyst; a reactive silicone oil having at least one alkoxy group in a terminal of a molecule; and a silane coupling agent, is used. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a transparent resin member such as a headlight cover for an automobile, and a method for recovering and maintaining the transparency of such a transparent resin member that has deteriorated in transparency over time, and such a transparent material. The present invention relates to a coating composition used for restoring the transparency of a resin member.

For example, a transparent resin member made of a polycarbonate resin, an acrylic resin, or the like is used for a cover in an automobile headlight (headlight), taillight (taillight), vehicle width light, turn signal, etc., for example, an automobile visor. It has been.
These transparent resin members have a problem that they become dull or yellowish over time due to, for example, adhesion of wax for automobile bodies, adhesion of snow melting agent, exposure to exhaust gas or sunlight, and transparency is lowered.

  On the other hand, Patent Document 1 relates to a resin cover used for a headlight part of an automobile, and provides a mirror finish as a means for restoring a portion where brightness is reduced due to aging or scratches caused by aging to a state similar to that of a new car. It has been proposed. Further, as a polishing agent for mirror finishing, a polishing agent for a resin cover, which is mainly composed of a mixture of hard stone powder, a solvent and water and contains a surfactant, has been proposed.

  Patent Document 2 proposes a transparency restoring agent that restores transparency lost due to scratches on the surface of a transparent resin material such as polycarbonate and acrylic without losing the properties of the material. Furthermore, the same document contains a water-soluble solution containing 5 to 40% by weight as a solid content of a synthetic resin emulsion that forms a coating film having a refractive index and light transmittance equivalent or similar to those of the transparent resin material. Sexual liquids have been proposed.

Patent Document 3 discloses a moisture curable silicone resin, a curing catalyst, a reactive silicone oil, a silane coupling agent, and a colorant, and is coated on a transparent surface of a transparent part made of a plastic product or the like. Colored coating compositions for forming and coloring are proposed.
JP 2007-297557 A JP-A-6-16977 JP 2006-143970 A

However, when the surface of the transparent resin member is polished using the abrasive described in Patent Document 1, fine scratches remain on the polished surface, and dirt enters the scratches. This causes the problem of causing dirt to adhere.
Moreover, the transparency restoring agent described in Patent Document 2 is likely to cause unevenness in the formed coating film due to the molecular weight of the synthetic resin, and it is difficult to impart sufficient hardness to the coating film. There is a problem that newly attached dirt easily enters the coating film. And since the said coating film has low adhesiveness with respect to polycarbonate-type resin and acrylic resin, and its weather resistance is not enough, it cannot maintain the restoring effect of transparency over a long period of time.

Further, the colored coating composition described in Patent Document 3 is for forming a film on a transparent surface of a transparent part made of a plastic product or the like and coloring it by a simple process, and the transparency of the transparent part itself. It does not improve. Rather, the transparency of the transparent part is reduced by being colored.
Accordingly, an object of the present invention is to recover the transparency of a transparent resin member whose transparency has deteriorated over time and to maintain the transparency for a long period of time, and to recover the transparency of the transparent resin member. And a coating composition used for the purpose.

  In order to achieve the above object, the method for recovering transparency of a transparent resin member of the present invention is a method for recovering the transparency of a transparent resin member whose transparency has deteriorated over time. A pretreatment step of pretreating the surface with a pretreatment agent; and an application step of applying a coating composition to a treated surface of the pretreated transparent resin member, wherein the coating composition is a moisture-curable silicone. It contains a resin or oligomer, a curing catalyst, a reactive silicone oil having at least one alkoxy group at the end of the molecule, and a silane coupling agent.

  In the method for recovering transparency of the transparent resin member, since the coating composition is applied to the surface of the transparent resin member, it is possible to form a silicone film that is stably held over a long period of time on the transparent resin member. it can. Further, the silicone film formed in this way covers the fine scratches over a long period of time even when fine scratches are generated on the surface of the transparent resin member due to, for example, pretreatment. It is held stably. For this reason, it is possible to prevent a problem that new dirt enters a fine flaw on the surface of the transparent resin member.

Therefore, according to the method for recovering transparency of the transparent resin member of the present invention, it is possible to recover the transparency of the transparent resin member whose transparency has decreased over time, and to maintain the recovered transparency over a long period of time. it can.
Furthermore, in the coating step, a silicone film made of the coating composition is formed on the surface of the transparent resin member, so that the water repellency is improved on the surface of the transparent resin member, and the surface of the transparent resin member is antifouling. Sex is imparted.

In the method for recovering transparency of the transparent resin member of the present invention, it is preferable that the pretreatment is a treatment for adjusting the surface roughness of the surface to be treated so that the arithmetic average roughness Ra is 0.1 μm or less. It is.
By pre-treating the surface to be treated in advance so that the surface roughness is in the above range, the coating composition is then applied to improve the transparency recovery effect of the transparent resin member. .

  In the method for recovering transparency of the transparent resin member of the present invention, it is preferable that the moisture curable silicone resin or oligomer is an alkoxysilane compound represented by the following general formula (1) or a partial hydrolysis condensate thereof.

(In the general formula (1), R ¹ represents a hydrogen atom or a substituted or unsubstituted monovalent hydrocarbon group, R ² represents an alkyl group, and m represents an integer of 0 to 3. R ¹ and R ² may be the same or different from each other.
When the moisture curable silicone resin or oligomer of the coating composition used in the coating step is an alkoxysilane compound represented by the above formula (1) or a partially hydrolyzed condensate thereof, a silicone film comprising the above coating composition The strength and adhesiveness with the surface of the transparent resin member can be further improved. For this reason, the effect of restoring the transparency of the transparent resin member can be maintained for a longer period of time.

  In the method for recovering transparency of the transparent resin member of the present invention, it is preferable that the reactive silicone oil is a compound represented by the following general formula (2).

(In General Formula (2), R ³ and R ⁴ are the same or different from each other, and represent a substituted or unsubstituted monovalent hydrocarbon group, n represents an integer of 0 to 400, and p represents 0. Represents an integer of ~ 2)
When the reactive silicone oil of the coating composition used in the coating step is a compound represented by the above formula (2), the water repellency and antifouling property of the transparent resin member can be further improved.

Further, in the method for recovering transparency of the transparent resin member of the present invention, the silane coupling agent is a mercapto silane coupling agent, an epoxy silane coupling agent, an amino silane coupling agent, a methacryloxy silane coupling agent, and It is preferably at least one selected from the group consisting of isocyanate-based silane coupling agents.
When the silane coupling agent of the coating composition used in the coating step is at least one selected from the above group, the durability of the transparent resin member can be further improved.

In order to achieve the above object, a coating composition for recovering transparency of a transparent resin member of the present invention comprises a moisture curable silicone resin or oligomer, a curing catalyst, and a reactivity having at least one alkoxy group at the end of the molecule. It contains silicone oil and a silane coupling agent.
According to the coating composition for recovering transparency of the transparent resin member, it is possible to form a silicone film that is stably maintained over a long period of time on the surface of the transparent resin member. In addition, it is possible to improve the water repellency of the transparent resin member and to impart antifouling properties to the transparent resin member.

  According to the method for recovering transparency of a transparent resin member and the coating composition for recovering transparency of the present invention, it is possible to recover the transparency of a transparent resin member whose transparency has decreased over time due to dullness or yellowing. The restored transparency can be maintained over a long period of time. In addition, the water repellency of the transparent resin member can be improved, and antifouling properties can be imparted to the transparent resin member.

The transparent resin member transparency recovery method of the present invention includes a pretreatment step of pretreating the surface of a transparent resin member whose transparency has deteriorated with time with a pretreatment agent, and the transparent resin pretreated with the pretreatment agent. And an application step of applying a transparency recovery coating composition to the surface to be processed of the member.
Specifically, as the pretreatment step, for example, a polishing step in which the surface of the transparent resin member whose transparency has decreased with time is polished with an abrasive to remove dullness or yellowing sites generated on the surface of the transparent resin member. Is mentioned.

In the pretreatment step, for example, a pretreatment agent is supported on a support member, and a pretreatment is performed on a portion where dullness or yellowing occurs on the surface of the transparent resin member by a conventional method.
The pretreatment agent used in the pretreatment step includes, for example, abrasive particles, a lubricant, an organic solvent, a thickener, and water, and further includes a surfactant as necessary. .
The abrasive particles are hard particles such as alumina, silica, kaolin, cerium oxide, titania, zirconia, germania, manganese dioxide, iron oxide, tin oxide, silicon carbide, boron carbide, tungsten carbide, carbon black, diamond. Among these, alumina particles (alumina powder) are preferable. These abrasive particles can be used alone or in admixture of two or more.

The abrasive particles have a 50% particle size (median diameter D ₅₀ ) of preferably 1.4 μm or less, more preferably 0.1 to 1.4 μm, and particularly preferably 0.2 to 1. .1 μm.
When the surface of the transparent resin member is subjected to a pretreatment with a pretreatment agent containing abrasive particles having a 50% particle size of 1.4 μm or less, although it depends on the pretreatment method, it is generally a transparent resin. The surface roughness of the polished surface of the member is adjusted to an arithmetic average roughness Ra of 0.1 μm or less. The arithmetic average roughness Ra is the arithmetic average height of the contour curve described in JIS B 0601: 2001 “Product Geometrical Characteristics Specification (GPS) —Surface Properties: Contour Curve Method—Terms, Definitions, and Surface Property Parameters”. It is a parameter indicated by “Ra”.

Further, by adjusting the surface roughness of the pretreated surface of the transparent resin member to 0.1 μm or less with the arithmetic average roughness Ra, the scratches generated on the surface of the transparent resin member after the pretreatment step are made fine. Further, this can improve the effect of recovering the transparency of the transparent resin member through the application step described later.
The blending ratio of the abrasive particles is preferably 1 to 20 parts by weight, and more preferably 5 to 15 parts by weight with respect to 100 parts by weight of the total amount of the pretreatment agent. When the blending ratio of the abrasive particles exceeds the above range, the handling of the pretreatment agent may be deteriorated. On the other hand, if the blending ratio of the abrasive particles is less than the above range, the effect of removing the dullness and yellowing of the transparent resin member is reduced in the pretreatment step, and the effect of recovering the transparency of the transparent resin member is insufficient. There is a fear.

The lubricant imparts smoothness between the pretreatment agent supporting member (for example, woven fabric, non-woven fabric, buff, etc.) for supporting the pretreatment agent and the surface of the transparent resin member during pretreatment. And a component for suppressing excessive polishing of the surface of the transparent resin member by the abrasive particles.
Examples of the lubricating oil include synthetic oils such as glycerin, liquid paraffin, polybutene, α-olefin oligomer, alkylbenzene, polyol ester, phosphate ester, and silicone oil, and mineral oils such as spindle oil, neutral oil, and bright stock. Examples thereof include vegetable oils such as castor oil, soybean oil, coconut oil, linseed oil, cottonseed oil, rapeseed oil, drill oil and olive oil, and animal oils such as beef tallow, squalane and lanolin. These lubricating oils can be used alone or in admixture of two or more.

In the case of using a mixture of two or more kinds of lubricating oils, the combination is preferably, for example, a combination of glycerin, spindle oil, and castor oil.
The blending ratio of the lubricating oil is, for example, 1 to 10 parts by weight, preferably 2 to 7 parts by weight with respect to 100 parts by weight of the pretreatment agent. When the blending ratio of the lubricating oil exceeds the above range, the workability of the pretreatment is deteriorated. On the contrary, if the blending ratio of the lubricating oil is less than the above range, the degree of polishing of the surface of the transparent resin member by the abrasive particles becomes excessive, and the transparency recovery effect of the transparent resin member is obtained even after the subsequent coating process. May become insufficient.

When the lubricating oil is a combination of glycerin, spindle oil, and castor, the blending ratio of each of the above components is, for example, 25 to 150 parts by weight of spindle oil, for example, castor oil is 100 parts by weight of glycerin. 5 to 50 parts by weight.
Examples of the organic solvent include saturated aliphatic hydrocarbon solvents such as normal paraffin (for example, nonane, decane, dodecane, etc.), isoparaffin, naphthene, and the like, for example, petroleum aliphatic solvents such as kerosene, solvent naphtha, and stocked solvent. Examples thereof include terpene solvents such as camphor oil, turpentine oil, and pine oil. These organic solvents can be used alone or in admixture of two or more. In addition, the organic solvent is particularly preferably a saturated aliphatic hydrocarbon solvent among the above.

When a solvent other than the above is used, the transparent resin member may be damaged during the polishing process.
The blending ratio of the organic solvent is preferably 1 to 9 parts by weight, more preferably 3 to 8 parts by weight with respect to 100 parts by weight of the pretreatment agent. When the content ratio of the organic solvent exceeds the above range, the workability of the pretreatment may be reduced. On the contrary, when the content ratio of the organic solvent is less than the above range, the effect of the pretreatment may be reduced.

The thickener is a component for increasing the viscosity of the pretreatment agent, and is blended, for example, for the purpose of preventing the abrasive from scattering due to buff rotation during buffing.
Examples of the thickener include synthetic thickeners such as polyacrylic acid and sodium polyacrylate (completely neutralized product, partially neutralized product, etc.), for example, cellulosic thickeners such as carboxymethylcellulose and carboxyethylcellulose. Agents (semi-synthetic thickeners), for example, natural thickeners such as agar, carrageenan, xanthan gum and gum arabic. These thickeners can be used alone or in admixture of two or more. Further, among the above, the thickener is particularly preferably a synthetic thickener, and more preferably polyacrylic acid.

  Examples of the polyacrylic acid include associative alkali-soluble polyacrylic acid (acrylic polymer). Specifically, a commercially available product can be used as such polyacrylic acid. Examples of commercially available products of polyacrylic acid include Primal TT-615, Primal TT-935, Primal TT-950, Primal RM-4, and Primal RM-5 (above, manufactured by Rohm and Haas Japan Co., Ltd.). Is mentioned.

Moreover, when using polyacrylic acid as a thickener, Preferably, an alkali is used together. Examples of the alkali include inorganic alkalis such as sodium hydroxide and potassium hydroxide, and organic alkalis such as ammonia and triethanolamine. By adding such an alkali, the thickening action of polyacrylic acid is improved.
The blending ratio of the thickener is preferably 0.1 to 2.0 parts by weight, and more preferably 0.2 to 1.0 parts by weight with respect to 100 parts by weight of the pretreatment agent. When the blending ratio of the thickener exceeds the above range, the viscosity becomes excessively high and the workability of the pretreatment may be reduced. On the other hand, when the blending ratio of the thickener is less than the above range, there is a possibility that abrasive particles, scraps generated by the pretreatment, etc. are scattered during the pretreatment.

The surfactant is a component for improving the dispersibility of each of the above components in the pretreatment agent.
Examples of the surfactant include anionic surfactants such as sodium dodecylbenzenesulfonate, sodium lauryl sulfate, sodium polyoxyethylene alkyl ether sulfate, sodium polyoxyethylene alkyl phenyl ether sulfate, such as polyoxyethylene alkyl ether, Nonionic surfactants such as polyoxyethylene alkylphenyl ether, polyoxyethylene sorbitan fatty acid ester, and sucrose fatty acid ester are listed. These surfactants can be used alone or in admixture of two or more. Among the above, the surfactant is particularly preferably an anionic surfactant.

  The blending ratio of the surfactant is preferably less than 0.1 parts by weight and more preferably 0.09 parts by weight or less with respect to 100 parts by weight of the pretreatment agent. Moreover, although it is not limited to this, Usually, it is 0.01 weight part or more with respect to 100 weight part of pretreatment agents. When the compounding ratio of the surfactant exceeds the above range, the organic solvent is emulsified in water, and the workability of pretreatment may be reduced. In addition, the effect of pretreatment of the surface of the transparent resin member with the abrasive particles may be excessive.

The blending ratio of water is adjusted as the balance when 100 parts by weight of the pretreatment agent is blended with the above-mentioned blending ratios of abrasive particles, lubricating oil, organic solvent, thickener and surfactant.
The pretreatment agent is prepared by appropriately blending the above-described abrasive particles, lubricating oil, organic solvent, thickener, surfactant and water in the above-described blending ratio, and stirring and mixing. When the thickener is polyacrylic acid, an alkali is preferably added simultaneously with the blending of polyacrylic acid or before and after the blending of polyacrylic acid.

In addition, additives that are usually added to the pretreatment agent such as a rust preventive agent, an antiseptic agent, an antifreezing agent, a pigment, and a fragrance can be appropriately blended with the pretreatment agent.
In the pretreatment, for example, as described above, the pretreatment agent is carried on a carrying member such as a woven fabric, a non-woven fabric, or a buff, and then the carrying member carrying the pretreatment agent is placed on the surface of the transparent resin member. Press and rub several times to several tens of times.

The degree of pretreatment may be adjusted as appropriate according to the material of the transparent resin member and the degree of dullness or yellowing on the surface of the transparent resin member.
Although the usage-amount of a pretreatment agent is not specifically limited, Usually, it sets to 3-12 g / m < ² > with respect to the to-be-processed surface of a transparent resin member.
An application process is a process of apply | coating the coating composition for transparency recovery of the transparent resin member of this invention with respect to the surface of the transparent resin member pre-processed by the said pre-processing process.

In this coating step, for example, the transparency recovery coating composition is supported on a support member, and the transparency recovery coating composition is pressed against the surface of the transparent resin member pretreated in the pretreatment step. Rub it several times to several tens of times.
A coating composition for recovering transparency of a transparent resin member according to the present invention comprises a moisture-curable silicone resin or oligomer, a curing catalyst, a reactive silicone oil having at least one alkoxy group at the molecular end, and a silane coupling agent. Containing.

The moisture curable silicone resin or oligomer is, for example, a low molecular weight silicone resin or silicone oligomer having an alkoxysilyl group at the molecular end, and crosslinking of the alkoxysilyl group at room temperature and in the presence of a curing catalyst described later. Can be cured.
Examples of such a moisture curable silicone resin or oligomer include an alkoxysilane compound represented by the following general formula (1) or a partial hydrolysis condensate thereof.

(In the general formula (1), R ¹ represents a hydrogen atom or a substituted or unsubstituted monovalent hydrocarbon group, R ² represents an alkyl group, and m represents an integer of 0 to 3. R ¹ and R ² may be the same or different from each other.
In R ¹ , examples of the unsubstituted monovalent hydrocarbon group include an alkyl group, a cycloalkyl group, an aryl group, and an aralkyl group.

  Examples of the alkyl group include methyl, ethyl, propyl, isopropyl, butyl, isobutyl, sec-butyl, tert-butyl, pentyl, isopentyl, sec-pentyl, neopentyl, hexyl, heptyl, n-octyl, isooctyl, 2-ethylhexyl. , Nonyl, decyl, isodecyl, dodecyl, tetradecyl, hexadecyl, octadecyl and the like alkyl groups having 1 to 18 carbon atoms. Examples of the cycloalkyl group include cycloalkyl groups having 3 to 8 carbon atoms such as cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl, and cyclooctyl. Examples of the aryl group include aryl groups having 6 to 8 carbon atoms such as phenyl, tolyl, and xylyl. Examples of the aralkyl group include aralkyl groups having 7 or 8 carbon atoms such as benzyl, 1-phenylethyl, 2-phenylethyl, o, m, or p-methylbenzyl.

In R ¹ , examples of the substituted monovalent hydrocarbon group include those in which the hydrogen atom of the above-described unsubstituted monovalent hydrocarbon group is substituted with a substituent. Examples of such a substituent include a halogen atom (for example, chlorine, fluorine, bromine and iodine), hydroxyl, cyano, amino, carboxyl and the like. These substituents may be the same or different from each other. For example, 1 to 3 substituents may be substituted.

R ¹ is particularly preferably hydrogen, an alkyl group having 1 to 18 carbon atoms, or an aryl group having 6 to 8 carbon atoms, among the groups described above.
In R ² , examples of the alkyl group include alkyl groups having 1 to 4 carbon atoms such as methyl, ethyl, propyl, isopropyl, butyl, isobutyl, sec-butyl, and tert-butyl.

R ¹ and R ² are independent of each other and may be the same or different from each other.
n shows the integer of 0-3, for example, Preferably, 1 or 2 is shown.
Examples of the alkoxysilane compound represented by the general formula (1) include methyltrimethoxysilane, methyltriethoxysilane, methyltriisopropoxysilane, methyltributoxysilane, ethyltrimethoxysilane, propyltrimethoxysilane, and dimethyldimethoxy. Examples include silane, phenyltrimethoxysilane, diphenyldimethoxysilane, phenylmethyldimethoxysilane, tetramethoxysilane, tetraethoxysilane, tetraisopropoxysilane, tetrabutoxysilane, or a mixture thereof.

The partially hydrolyzed condensate of the alkoxysilane compound can be obtained by adding water to the above alkoxysilane compound and subjecting it to a temperature increase while stirring in the presence of a catalyst. Through this treatment, the alkoxysilane compound is partially hydrolyzed and condensed.
The moisture curable silicone resin or oligomer may be represented by the following average composition formula (3), for example.

(In the average composition formula (3), R ¹ represents a hydrogen atom or a substituted or unsubstituted monovalent hydrocarbon group, R ² represents an alkyl group, and a is an average value of 0. A value in the range of 40 to 1.70 is shown, and b is a value at which the content ratio of the OR ² group in the compound represented by the average composition formula (3) is 5% by weight or more in the average value. Show.)
In the average composition formula (3), as ^{R 1} and ^{R 2,} include the same ones as ^{R 1} and ^{R 2} in the general formula (1) described above.

The kinematic viscosity of the moisture-curing silicone resin or oligomer, as the value of at 25 ° C., for example, a 0.1~200mm ² / s, preferably, 0.5 to 100 mm ² / s. When the kinematic viscosity of the moisture curable silicone resin or oligomer exceeds 200 mm ² / s (25 ° C.), a uniform film may not be obtained.
The moisture curable silicone resin or oligomer is commercially available. Commercially available products include, for example, product name “KR-217”, product name “KR-500”, product name “X-40-2308”, product name “X-40-9238”, product name “KC-89S” (Shin-Etsu Chemical) Kogyo Co., Ltd.). These moisture curable silicone resins or oligomers may be used alone or in combination of two or more.

  The blending ratio of the moisture curable silicone resin or oligomer is, for example, 0.1 to 90 parts by weight, preferably 1 to 70 parts by weight, more preferably 3 to 100 parts by weight of the coating composition for recovering transparency. 50 parts by weight, particularly preferably 5 to 30 parts by weight. When the blending ratio of the moisture curable silicone resin or oligomer is below the above range, there is a possibility that a silicone film cannot be sufficiently formed on the surface of the transparent resin member. For this reason, there is a possibility that the effect of repairing the fine scratches generated on the surface of the transparent resin member in the polishing step and restoring the transparency of the transparent resin member may not be sufficiently obtained. On the contrary, when the blending ratio of the moisture curable silicone resin or oligomer exceeds the above range, the workability of applying the coating composition for recovering transparency may be lowered. Moreover, there exists a possibility that the silicone film cannot be formed uniformly on the surface of the transparent resin member.

  Examples of the curing catalyst include a catalyst capable of curing the moisture curable silicone resin or oligomer. Specifically, although not particularly limited, for example, organic tin compounds such as dibutyltin diacetate, dibutyltin dioctylate, dibutyltin dilaurate, such as aluminum tris (acetylacetone), aluminum tris (acetoacetate ethyl), aluminum diisopropoxy Organoaluminum compounds such as (acetoacetate ethyl), for example, zirconium (acetylacetone), zirconium tris (acetylacetone), zirconium tetrakis (ethylene glycol monomethyl ether), zirconium tetrakis (ethylene glycol monoethyl ether), zirconium tetrakis (ethylene glycol monobutyl ether) Organic zirconium compounds such as titanium tetrakis (ethylene glycol monomer) Ether ether), titanium tetrakis (ethylene glycol monoethyl ether), organic metal compounds such as titanium tetrakis (ethylene glycol monobutyl ether), for example, mineral acids such as hydrochloric acid, nitric acid, sulfuric acid, phosphoric acid, formic acid, Acids such as organic acids such as acetic acid, oxalic acid and trifluoroacetic acid, for example, inorganic bases such as ammonia, sodium hydroxide and potassium hydroxide, alkalis such as organic bases such as ethylenediamine and alkanolamine, such as amino-modified silicone And amino compounds such as aminosilane, silazane, and amines. Among these curing catalysts, an organic tin compound, an organic aluminum compound, an organic titanium compound, and mineral acids are preferable, and an organic titanium compound is more preferable.

The curing catalyst is available as a commercial product, and examples thereof include product name “D-20”, product name “DX-9740”, product name “DX-175” (manufactured by Shin-Etsu Chemical Co., Ltd.). These curing catalysts may be used alone or in combination of two or more.
The blending ratio of the curing catalyst is, for example, 0.1 to 70 parts by weight, preferably 1 to 50 parts by weight, more preferably 2 to 20 parts by weight, with respect to 100 parts by weight of the moisture curable silicone resin or oligomer. Preferably, it is 3 to 15 parts by weight.

  Moreover, the curing catalyst may be previously contained in the moisture curable silicone resin or oligomer. A commercially available product of a moisture curable silicone resin or oligomer is known in advance to contain a curing catalyst. Specifically, as such a commercially available product, for example, the product name “KR-400” (cured) Catalyst containing 10% by weight of catalyst (product name “DX-9740”, manufactured by Shin-Etsu Chemical Co., Ltd.), product name “KR-401” (containing curing catalyst (product name “DX-175” of 5% by weight), Shin-Etsu The moisture curable silicone resin or oligomer containing these curing catalysts in advance may be used alone or in combination of two or more.

  Examples of reactive silicone oils include so-called side chain-modified silicone oils having organic groups in part of the side chain of polysiloxane, so-called double-end type modified silicone oils having organic groups at both ends of polysiloxane. , So-called single-end-type modified silicone oil having an organic group at one end of polysiloxane, so-called side-chain double-end-type modified silicone oil having organic groups at both ends and both ends of polysiloxane , Etc. Examples of the organic group include, but are not limited to, an alkoxy group, an amino group, an epoxy group, a carbinol, a mercapto group, a carboxyl group, a polyether, and an aralkyl group.

Among them, preferred is a modified silicone oil having at least one alkoxy group at the end of the molecule, a modified silicone oil having an amino group at the side chain and an alkoxy group at both ends, and particularly preferred is a molecular silicone oil. Examples include modified silicone oils having at least one alkoxy group at the terminal.
Examples of the modified silicone oil having at least one alkoxy group at the end of the molecule include a reactive silicone oil represented by the following general formula (2).

(In General Formula (2), R ³ and R ⁴ are the same or different from each other, and represent a substituted or unsubstituted monovalent hydrocarbon group, n represents an integer of 0 to 400, and p represents 0. Represents an integer of ~ 2)
In R ³ and R ⁴ , examples of the substituted or unsubstituted monovalent hydrocarbon group include a methyl group, an ethyl group, a propyl group, a 3,3,3-trifluoropropyl group, a butyl group, a hexyl group, and a phenyl group. Groups and the like. Among these, R ³ is preferably a methyl group, and R ⁴ is preferably a methyl group or an ethyl group, and more preferably a methyl group.

n is, for example, 0 to 400, preferably 5 to 350, and more preferably 5 to 250.
The reactive silicone oil is available as a commercial product. As a commercial item, product name "X-24-9377", product name "X-24-9011" (above, Shin-Etsu Chemical Co., Ltd. product) etc. are mentioned, for example. These reactive silicone oils may be used alone or in combination of two or more.

The kinematic viscosity of the reactive silicone oil is, for example, 0.65 to 1500 mm ² / s as a value at 25 ° C., preferably ^{2 to} 1000 mm ² / s, and more preferably ^{2 to} 500 mm ² / s. is there. When the kinematic viscosity of the reactive silicone oil exceeds 1000 mm ² / s (25 ° C.), a uniform film may not be obtained.
The compounding ratio of the reactive silicone oil is, for example, 0.1 to 45 parts by weight, preferably 0.3 to 30 parts by weight, and more preferably 1 to 15 parts per 100 parts by weight of the moisture curable silicone resin or oligomer. Part by weight, particularly preferably 2 to 10 parts by weight. When the blending ratio of the reactive silicone oil is below the above range, the effect of imparting water repellency and antifouling property to the transparent resin member is lowered. On the other hand, if the proportion of the reactive silicone oil exceeds the above range, it may be difficult to maintain the effect of imparting water repellency and antifouling properties.

Examples of the silane coupling agent include silane coupling agents such as mercapto-based, epoxy-based, amino-based, methacryloxy-based, and isocyanate-based, preferably mercapto-based, epoxy-based, amino-based, methacryloxy-based, and isocyanate-based. Is mentioned.
Examples of the mercapto silane coupling agent include γ-mercaptopropyltrimethoxysilane, γ-mercaptopropyltriethoxysilane, and the like. Examples of the epoxy silane coupling agent include 3-glycidoxypropyltriethoxysilane, 2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, 3-glycidyl Sidoxypropyltrimethoxysilane and the like can be mentioned. Examples of amino silane coupling agents include γ-aminopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, 3- (2-aminoethyl) aminopropyltrimethoxysilane, and 3- (2-aminoethyl) amino. Examples include propyltriethoxysilane and 3- (2-aminoethyl) aminopropylmethyldimethoxysilane. Examples of the methacryloxy silane coupling agent include 3-methacryloxypropylmethyldimethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropylmethyldiethoxysilane, and 3-methacryloxypropyltriethoxysilane. It is done. Examples of the isocyanate-based silane coupling agent include 3-isocyanatopropyltriethoxysilane.

Moreover, a silane coupling agent is available as a commercial item. Specifically, examples of commercially available products include a product name “KBE-502” and a product name “KBE-9007” (hereinafter, Shin-Etsu Chemical Co., Ltd.). These silane coupling agents may be used alone or in combination of two or more.
The blending ratio of the silane coupling agent is, for example, 0.1 to 50 parts by weight, preferably 1 to 40 parts by weight, and more preferably 5 to 30 parts by weight with respect to 100 parts by weight of the moisture curable silicone resin or oligomer. Particularly preferred is 10 to 30 parts by weight. When the blending ratio of the silane coupling agent is within the above range, the strength of the silicone film on the polishing surface of the transparent resin member and the fixability between the polishing surface and the silicone film can be improved.

The coating composition for recovering transparency of the transparent resin member can be appropriately prepared by blending the above-described components in a solvent or the like.
Any solvent may be used as long as it can dissolve or disperse the moisture-curable silicone resin or oligomer, the curing catalyst, the reactive silicone oil, and the silane coupling agent. Therefore, alcohol solvents such as methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, 2-methyl-1-propanol and 2-methyl-2-propanol are not particularly limited. (Preferably, an alcohol solvent having 1 to 4 carbon atoms), for example, petroleum solvents such as mineral spirits, for example, hexane, heptane, n-octane, isooctane, nonane, decane, undecane, dodecane, etc. Examples thereof include a hydrogen solvent (preferably an aliphatic hydrocarbon solvent having 6 to 12 carbon atoms), for example, an aromatic hydrocarbon solvent such as benzene, toluene and xylene. These solvents may be used alone or in combination of two or more.

  The mixing ratio of the solvent is 100 parts by weight of the coating composition for recovering transparency. The moisture-curable silicone resin or oligomer, the curing catalyst, the reactive silicone oil having at least one alkoxy group at the end of the molecule, and the silane cup It adjusts as a remainder when a ring agent is mix | blended with the above-mentioned mixture ratio, respectively. Therefore, although not limited to this, it is preferably 5 to 99% by weight, more preferably 20 to 95% by weight, based on the total weight of the coating composition for recovering transparency.

  In addition, the coating composition for recovering the transparency of the transparent resin has other additives such as, for example, a viscosity modifier, an anti-aging agent, a fragrance, a surfactant, and a silicone powder, as long as the effects of the present invention are not impaired. Can be appropriately blended as necessary. When silicone powder is used as an additive, it is possible to efficiently perform wiping (removal of excessively supplied transparency recovery coating composition from the transparent resin member) after application of the transparency recovery coating composition. .

In the coating treatment, for example, as described above, the coating composition for recovering the transparency of the transparent resin member is supported on the supporting member for the surface treatment agent, and then the supporting member on which the coating composition for recovering the transparency is supported. Press against the surface to be treated of the transparent resin member and rub it several times to several tens of times.
Examples of the supporting member for supporting the transparency recovery coating composition include sponge, woven fabric, and non-woven fabric.

What is necessary is just to adjust suitably the grade of application | coating according to the material of a transparent resin member, the grade of the grinding | polishing process with respect to a transparent resin member, etc.
The amount of the coating composition for recovering transparency is appropriately set according to the material of the transparent resin member and the degree of polishing treatment. Therefore, the coating amount of the coating composition for recovering transparency is not particularly limited. For example, it is preferably 5 to 50 g / m ² and more preferably 10 to 30 g / m ² with respect to the polished surface of the transparent resin member. a m ^2.

  The application method of the coating composition for recovering transparency is not limited to the above method, and other application methods can be adopted. Examples of other application methods include sponge, woven fabric, non-woven fabric brush coating, and spray coating. These application methods can be appropriately selected depending on the purpose and application of application of the coating composition for recovering transparency, the shape of the transparent resin member to be applied, and the like. In addition, after application | coating, what is necessary is just to wipe off if necessary after progress for a predetermined time.

  In this way, the coating composition for recovering transparency applied to the polished surface of the transparent resin member is acted by the curing catalyst and moisture in the air as the solvent component volatilizes. The oligomer is cured to form a silicone film on the polished surface. The silicone film repairs fine scratches generated on the polished surface of the transparent resin member and restores the transparency of the transparent resin member.

  Moreover, the moisture curable silicone resin or oligomer is cured on the polishing surface of the transparent resin member, so that the moisture curable silicone resin or oligomer itself forms a film, while the moisture curable silicone resin or oligomer has an alkoxy group, A bond is formed with the alkoxy group of the reactive silicone oil. For this reason, the reactive silicone oil does not disappear over time, and is fixed to the polishing surface of the transparent resin member via the moisture-curable silicone resin or oligomer, and has excellent water repellency and antifouling properties on the polishing surface. Give.

The coating composition for recovering transparency needs only to be applied to the surface of the transparent resin member and then dried at room temperature. Therefore, it can be easily and easily applied to the surface of the transparent resin member.
Further, the silicone film formed from the above-mentioned transparency recovery coating composition has the same antifouling property as hydrophilic stains not only against hydrophilic stains but also lipophilic stains. Yes. For this reason, for example, it is possible to prevent the attachment of exhaust gas or the like of automobiles, and it is possible to easily remove the dirt caused by the attached exhaust gas.

As described above, according to the present invention, the transparency of the transparent resin member can be recovered and the transparency can be maintained over a long period of time through the pretreatment step and the coating step.
In the method for recovering transparency of the transparent resin member of the present invention, the transparent resin member may be, for example, a cover for an automobile headlight (headlight), taillight (taillight), vehicle width light, turn signal, etc., for example, an automobile visor. For example, a transparent resin member for automobiles. These transparent resin members for automobiles are generally formed from polycarbonate resin, acrylic resin, or the like.

  Moreover, the transparency recovery method of the transparent resin member of this invention is applicable to transparent resin members, such as a cover for outdoor lighting apparatuses, for example besides the said transparent resin member for motor vehicles. Specifically, examples of the cover for the outdoor lighting device include a cover for a headlight in a train, a ship, an aircraft, and the like, for example, a cover for a streetlight, and a cover for a light for an outdoor display such as a road sign. Note that these outdoor lighting device covers are generally formed of polycarbonate resin, acrylic resin, or the like.

  In addition, the coating composition for recovering transparency of the transparent resin member of the present invention is applied as a treatment agent for recovering the transparency of the transparent resin member by applying it after the pretreatment for the transparent resin member.

Next, an Example and a comparative example are given and this invention is demonstrated.
(1) Preparation of pretreatment agents Pretreatment agents A to D having the following compositions were prepared as pretreatment agents for transparent resin members.
Pretreatment agent A
As abrasive particles, alumina powder (product name “A-32”, manufactured by Nippon Light Metal Co., Ltd.) having a 50% particle size (D ₅₀ ) of 1 μm was used.

  10.0 parts by weight of the abrasive particles, 2.0 parts by weight of glycerin (lubricating oil), 1.2 parts by weight of spindle oil (lubricating oil, manufactured by Nippon Oil Co., Ltd.), and castor oil (lubricating oil) 0. 3 parts by weight, 8.0 parts by weight of an isoparaffin hydrocarbon (organic solvent, product name “IP Solvent 2028”, manufactured by Idemitsu Kosan Co., Ltd.), an anionic surfactant (product name “Neogen (registered trademark) S-20A”, Daiichi Kogyo Seiyaku Co., Ltd.) 0.4 parts by weight, thickener (product name “Primal TT-615”, manufactured by Rohm and Haas Japan) 1.0 part by weight, water 76.5 parts by weight And 0.5% by weight of a 10% aqueous solution of thorium hydroxide were mixed, stirred and mixed to obtain a pretreatment agent A.

Pretreatment agent B
As the abrasive particles, calcined kaolin (product name “Satinton No. 5”, manufactured by BASF) having a 50% particle size (D ₅₀ ) of 0.8 μm was used.
The same component as the pretreatment agent A, except that 10.0 parts by weight of the abrasive particles (product name “Satinton No. 5”) was used instead of 10.0 parts by weight of alumina powder (product name “A-32”). Were mixed in the same amount, and the pretreatment agent B was obtained by stirring and mixing.

Pretreatment agent C
As abrasive particles, alumina powder (product name “A-11”, manufactured by Nippon Light Metal Co., Ltd.) having a 50% particle size (D ₅₀ ) of 50 μm was used.
In place of 10.0 parts by weight of alumina powder (product name “A-32”), 10.0 parts by weight of the abrasive particles (product name “A-11”) were used, and the same components as pretreatment agent A were used. A pretreatment agent (abrasive) C was obtained by mixing in the same amount, stirring and mixing.

Pretreatment agent D
Isoparaffinic hydrocarbon (product name “IP Solvent 2028”) was used as it was as a pretreatment agent.

(2) Preparation of coating composition for recovering transparency of transparent resin member As coating composition for recovering transparency of transparent resin member, the compositions shown in the following Preparation Examples 1-8 and Comparative Preparation Examples 1-6 are prepared. did.
Preparation Example 1
Moisture curable silicone resin (product name “KR-500”, organic substituent: methyl, alkoxy group: methoxy, medium polymerization type, kinematic viscosity 20 mm ² / s (25 ° C.), manufactured by Shin-Etsu Chemical Co., Ltd.) 20.0 weight Parts, 0.9 part by weight of a curing catalyst (organic titanium compound, product name “D-20”, manufactured by Shin-Etsu Chemical Co., Ltd.), reactive silicone oil (terminal alkoxy group-modified type (methoxy type), product name “X-” 24-9377 ”, kinematic viscosity 6 mm ² / s (25 ° C., manufactured by Shin-Etsu Chemical Co., Ltd.) 0.8 part by weight, silane coupling agent (3-methacryloxypropylmethyldiethoxysilane, methacryloxy series, product name“ "KBE-502" (manufactured by Shin-Etsu Chemical Co., Ltd.) 5.0 parts by weight and isopropyl alcohol 73.3 parts by weight, each component is completely stirred To obtain a coating composition for recovering transparency.

Preparation Examples 2 and 3
The amount of the reactive silicone oil (product name “X-24-9377”) is 0.3 parts by weight in Preparation Example 2, 5 parts by weight in Preparation Example 3, and isopropyl so that the total is 100 parts by weight. A coating composition for recovering transparency was obtained in the same manner as in Adjustment Example 1 except that the blending amount of alcohol was adjusted appropriately.

Preparation Examples 4 and 5
The blending amount of the silane coupling agent (product name “KBE-502”) is 1.5 parts by weight in Preparation Example 4, 8 parts by weight in Preparation Example 5, and further, the total amount of isopropyl alcohol is 100 parts by weight. A coating composition for recovering transparency was obtained in the same manner as in Adjustment Example 1 except that the blending amount was appropriately adjusted.

Preparation Example 6
As the reactive silicone oil, instead of 0.8 parts by weight of the above “X-24-9377”, a terminal carbinol group-modified type (product name “X-22-4015”, kinematic viscosity 130 mm ² / s (25 ° C. ), Shin-Etsu Chemical Co., Ltd.) A coating composition for recovering transparency was obtained in the same manner as in Preparation Example 1, except that 0.8 part by weight was used.

Preparation Example 7
30.0 parts by weight of moisture curable silicone oligomer (product name “KR-400”, organic substituent: methyl, high hardness type, kinematic viscosity 1.2 mm ² / s (25 ° C.), manufactured by Shin-Etsu Chemical Co., Ltd.) Curing catalyst (organoaluminum compound, product name “DX-9740”, manufactured by Shin-Etsu Chemical Co., Ltd.) 3.4 parts by weight, reactive silicone oil (product name “X-24-9377”) 1.5 parts by weight, and silane Coupling agent (product name “KBE-502”) 6.0 parts by weight and 59.1 parts by weight of isopropyl alcohol are blended, and each component is completely dissolved by stirring to obtain a coating composition for restoring transparency. It was.

Preparation Example 8
Moisture curable silicone oligomer (product name “X-40-175”, organic substituent: methyl / phenyl, bending / impact resistance type, kinematic viscosity 22 mm ² / s (25 ° C.), manufactured by Shin-Etsu Chemical Co., Ltd.) 10.0 parts by weight of a solid content, 0.5 parts by weight of a curing catalyst (organic titanium compound, product name “DX-175”, manufactured by Shin-Etsu Chemical Co., Ltd.), and reactive silicone oil (product name “X-24-9377”) ) 0.6 parts by weight, 2.0 parts by weight of a silane coupling agent (product name “KBE-502”) and 86.9 parts by weight of isopropyl alcohol are mixed, and each component is completely dissolved by stirring. A coating composition for recovering transparency was obtained.

Comparative Preparation Example 1
Moisture curable silicone oligomer (product name “KR-400”) with a solid content of 18.8 parts by weight, curing catalyst (product name “DX-9740”) with 2.1 parts by weight, and reactive silicone oil (product name “X-24”). −9377 ”) 0.8 part by weight and 78.3 parts by weight of isopropyl alcohol were blended, and each component was completely dissolved by stirring to obtain a coating composition for recovering transparency.

In addition, the silane coupling agent was not mix | blended with the coating composition for transparency recovery of the comparative preparation example 1. FIG.
Comparative Preparation Example 2
19.9 parts by weight of a solid content of a moisture curable silicone oligomer (product name “X-40-175”), 1.0 part by weight of a curing catalyst (product name “DX-175”), and a silane coupling agent (product name “KBE”). -502 ") 5.0 parts by weight and 74.1 parts by weight of isopropyl alcohol were blended and each component was completely dissolved by stirring to obtain a coating composition for recovering transparency.

In addition, reactive silicone oil was not mix | blended with the coating composition for transparency recovery of this comparative preparation example 2. FIG.
Comparative Preparation Example 3
Isopropyl alcohol is blended with silicone resin (film forming component, silicone graft acrylic resin emulsion, product name “X24-798A”, manufactured by Shin-Etsu Chemical Co., Ltd.), and the solid content of the silicone graft acrylic resin is 20 After adjusting to 0.0 parts by weight, they were thoroughly mixed by stirring to obtain a coating composition for recovering transparency.

Comparative Preparation Example 4
Polyethylene acrylate copolymer emulsion (film forming component, product name “Primal B-924”, manufactured by Rohm & Haas Japan Co., Ltd.) with a solid content of 15.0 parts by weight, diethylene glycol monoethyl ether 2.5 Part by weight was blended, and water was further blended to make the total weight 100 parts by weight, and these were completely dissolved by stirring to obtain a coating composition for recovering transparency.

Comparative Preparation Example 5
20.0 parts by weight of reactive silicone oil (product name “KF-857”) and 80.0 parts by weight of isopropyl alcohol were blended and completely dissolved by stirring to obtain a coating composition for recovering transparency.
Comparative Preparation Example 6
Moisture curable silicone resin (product name “KR-500”) 18.0 parts by weight, curing catalyst (product name “D-20”) 0.9 parts by weight, reactive silicone oil (product name “X-24-9377”) ) 0.8 parts by weight, 2.0 parts by weight of a silane coupling agent (product name “KBE-502”), and 1.0 part by weight of a colorant (product name “cyanine blue 4930PK”, manufactured by Dainichi Seika Kogyo Co., Ltd.) And 77.3 parts by weight of isopropyl alcohol were mixed and each component was completely dissolved by stirring to obtain a coating composition for recovering transparency.

  About the coating composition for transparency recovery of the said preparation examples 1-9 and comparative preparation examples 1-6, the composition is shown in Table 2.

  In Table 2 and Table 3, the symbol “A” in the column of <Container of coating composition for transparency recovery> represents a moisture curable silicone resin / oligomer, and symbol “A ′” represents a component for film formation. The symbol “B” indicates a curing catalyst, the symbol “C” indicates a reactive silicone oil, the symbol “C ′” indicates a non-reactive silicone oil, and the symbol “D” indicates a silane coupling. The symbol “E” indicates a colorant, and the symbol “F” indicates a solvent / dispersion medium.

(3) Evaluation test By using the pretreatment agent prepared in (i) above and the coating composition for transparency recovery prepared in (ii) above in the combinations shown in Table 4 and Table 5 below, Construction examples (Examples 1 to 9, Comparative Examples 1 to 9, and Reference Examples) as methods for recovering the transparency of the resin member were evaluated.

The procedure of the concrete construction method (transparency recovery method of a transparent resin member) is as follows.
First, a transparent resin cover for a dull headlight of an automobile (polycarbonate resin, automobile: 2005 Corolla) was treated with any of the pretreatment agents A to D. In the reference example, no pretreatment was performed.
This pretreatment was performed by impregnating each of the pretreatment agents A to D into a non-woven fabric, pressing it against the surface of the headlight transparent resin cover by hand, and rubbing it several times. The amount of pretreatment agent used was set to about 20 g / m ² with respect to the surface of the headlight transparent resin cover.

Next, the coating composition for transparency recovery obtained in Preparation Examples 1 to 8 and Comparative Preparation Examples 1 to 6 was applied to the transparent resin cover for headlights (coating treatment). In Comparative Example 9, no coating treatment was performed.
The above coating treatment is performed by impregnating a urethane sponge cut into 3 cm × 3 cm with the coating composition for restoring transparency, pressing it against the surface of the pretreated headlight transparent resin cover by hand, and rubbing it lightly several times. It was done by attaching. The coating amount of the coating composition for recovering transparency was set to about 5 g / m ² with respect to the surface of the headlight transparent resin cover.

After the coating treatment, the state of the headlight transparent resin cover was observed, and the following items (i) to (vi) were evaluated.
(I) Workability The applicability of the coating composition for recovering transparency to the headlight transparent resin cover was evaluated according to the following criteria.

A: The coating composition for recovering transparency was extremely good and could be applied without causing uneven coating.
◯: The coating composition for recovering transparency was good and could be applied with almost no coating unevenness.
Δ: Although coating unevenness of the coating composition for restoring transparency slightly occurred, it was practically acceptable.

X: The coating unevenness of the coating composition for recovering transparency was remarkable and was not suitable for practical use.
(Ii) Transparency With respect to the headlight transparent resin cover to which the coating composition for restoring transparency was applied, the visible light transmittance was measured with an apparatus manufactured by Tintometer.

  The measurement of the visible light transmittance was performed immediately after the coating treatment of the coating composition for recovering transparency, 6 months after the coating, and 12 months after the coating. In addition, after application | coating of the coating composition for transparency recovery to a headlight transparent resin cover, the motor vehicle used for the said test was parked and stored in the outdoor parking lot (without a roof). Moreover, the car used for the test was allowed to run for at least 20 hours every week (the same applies hereinafter).

Transparency was evaluated according to the following criteria by comparing the measurement result of the visible light transmittance with the visible light transmittance of a new headlight transparent resin cover.
A: Transparency was completely recovered (the measured value of visible light transmittance was 90% or more with respect to the new visible light transmittance).
○: Transparency was almost recovered (the measured value of visible light transmittance was 70% or more and less than 90% with respect to a new product).

(Triangle | delta): Although the dullness remained on the surface of the headlight transparent resin cover, transparency was recovered to a practically acceptable level (50% or more and less than 70% with respect to a new article).
X: Transparency did not recover, and dullness comparable to the state where the pretreatment and the coating treatment were not performed remained (less than 50% of the new product).
(Iii) Gloss About the headlight transparent resin cover to which the coating composition for recovering transparency was applied, the surface 60 ° gloss was measured with a gloss checker (gloss meter).

The 60 ° gloss measurement was performed immediately after the application of the coating composition for recovering transparency, 6 months after application, and 12 months after application. The headlight transparent resin cover was left outdoors after application of the coating composition for recovering transparency.
The gloss was evaluated according to the following criteria by comparing the measurement result of 60 ° gloss with the value of 60 ° gloss in a new headlight transparent resin cover.

A: The gloss was completely recovered (the measured value of 60 ° gloss was 90% or more of the new 60 ° gloss value).
○: Gloss was almost recovered (measured value of 60 ° gloss was 70% or more and less than 90% of the new product).
Δ: Although the degree of gloss was slightly low, it was recovered to an acceptable level for practical use (the measured value of 60 ° gloss was 50% or more and less than 70% of the new product).

X: The gloss was not recovered (the measured value of 60 ° gloss was less than 50% of the new product).
(Iv) Water repellency By wetting the surface of the headlight transparent resin cover coated with the transparency recovery coating composition with water, and visually observing the state of polka dots (degree of repellency) formed on the surface, The water repellency was evaluated.

A: The polka dots were repelled in a substantially spherical shape, and the water repellency was extremely good.
○: Although the polka dots were deformed, the repelling was sufficiently generated and the water repellency was good.
Δ: Although the degree of repelling was slightly low, the degree of water repellency was practically acceptable.
X: Almost no repelling. The water repellency was insufficient.

(V) Antifouling property The antifouling property was evaluated according to the following criteria by visually observing the contamination state of the surface of the headlight transparent resin cover coated with the transparency recovery coating composition.
Evaluation of antifouling property was performed immediately after the coating treatment of the coating composition for recovering transparency, 6 months after the application, and 12 months after the application.

A: Not dirty. The antifouling property was very good.
○: Almost unstained. Antifouling property was good.
Δ: Some contamination was observed. Although the antifouling property was slightly low, it was acceptable for practical use.
X: Dirt was remarkable. Antifouling property was insufficient.

(Vi) Durability JIS K 5600-5-11 _{: 1999} “Paint General Test Method—Part 5: Mechanical Properties of Coating Film” with respect to the headlight transparent resin cover to which the coating composition for recovering transparency was applied In accordance with the provisions of Section 11: Cleaning Resistance, a wet abrasion resistance test was conducted. Thereafter, the surface of the headlight transparent resin cover was visually observed, and its durability was evaluated according to the following criteria.

A: No scratches or cloudiness were observed on the surface of the headlight transparent resin cover, and the durability was extremely good.
○: Slight scratches were observed on the surface of the headlight transparent resin cover, but the durability was good.
Δ: Scratches were observed on the surface of the headlight transparent resin cover, but the durability was practically acceptable.

X: Scratches on the surface of the headlight transparent resin cover were remarkable and unsuitable for practical use.
Tables 4 and 5 show the evaluation results of the evaluation items (i) to (vi).

As shown in Table 4, in all of Examples 1 to 9, the workability of the treatment for recovering the transparency of the transparent resin member was good, and the transparency recovery effect was also good. Moreover, the transparency recovery effect could be maintained over a long period.
On the other hand, in Comparative Examples 1 to 9, practically inappropriate results were obtained for any of the above evaluation items.

In addition, in the reference example which did not perform pre-processing, although the transparency recovery effect of the transparent resin member appeared by the application | coating process, the grade was low compared with Examples 1-9.
The present invention is not limited to the above description, and various design changes can be made within the scope of the matters described in the claims.

Claims (7)

A method for recovering the transparency of a transparent resin member whose transparency has decreased over time,
A pretreatment step of pretreating the surface of the transparent resin member with a pretreatment agent, and an application step of applying a coating composition to the treated surface of the pretreated transparent resin member,
The coating composition contains a moisture curable silicone resin or oligomer, a curing catalyst, a reactive silicone oil having at least one alkoxy group at the end of the molecule, and a silane coupling agent. A method for recovering the transparency of a transparent resin member.   The method for recovering transparency of a transparent resin member, wherein the pretreatment is a treatment for adjusting the surface roughness of the surface to be treated so that the arithmetic average roughness Ra is 0.1 μm or less. 3. The transparent resin member according to claim 1, wherein the moisture-curable silicone resin or oligomer is an alkoxysilane compound represented by the following general formula (1) or a partial hydrolysis-condensation product thereof. Sexual recovery method.

(In general formula (1), R ¹ represents a hydrogen atom or a substituted or unsubstituted monovalent hydrocarbon group, R ² represents an alkyl group, and m represents an integer of 0 to 3. R ¹ and R ² may be the same or different from each other. The method for recovering transparency of a transparent resin member according to claim 1, wherein the reactive silicone oil is a compound represented by the following general formula (2).

(In General Formula (2), R ³ and R ⁴ are the same or different and represent a substituted or unsubstituted monovalent hydrocarbon group, n represents an integer of 0 to 400, and p represents 0. Represents an integer of ~ 2)   The silane coupling agent is at least one selected from the group consisting of mercapto silane coupling agents, epoxy silane coupling agents, amino silane coupling agents, methacryloxy silane coupling agents, and isocyanate silane coupling agents. The method for recovering transparency of a transparent resin member according to any one of claims 1 to 4, wherein   The method for recovering transparency of a transparent resin member according to claim 1, wherein the transparent resin member is a transparent resin member for automobiles.   A transparent resin member comprising: a moisture-curable silicone resin or oligomer; a curing catalyst; a reactive silicone oil having at least one alkoxy group at a molecular end; and a silane coupling agent. Coating composition for recovering properties.