JP2008127433A - Method for producing polymer having hydrolyzable silyl group in side chain and method for producing polymer having polysiloxane chain in side chain - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a polymer having a polysiloxane chain in the side chain and providing a colorless transparent surface coated film having excellent corrosion resistance, abrasion resistance, water resistance, solvent resistance and light resistance and low-temperature curability when coating a metal surface. <P>SOLUTION: This method for producing a polymer having a hydrolyzable silyl group in the side chain is characterized as follows: an unsaturated carboxylic acid ester represented by formula (I) (wherein, R<SP>1</SP>represents a hydrogen atom or a 1-3C alkyl group; R<SP>2</SP>represents a 2-6C alkylene group; R<SP>3</SP>and R<SP>4</SP>represent each a 1-3C alkyl group; and j is an integer of 1-3) and having the hydrolyzable silyl group is subjected to addition polymerization in the presence of a non-azo-based radical polymerization initiator in a mixed solvent of a 2-4C alkylene glycol mono-1-3C alkyl ether with a 2-4C alkylene glycol mono-1-3C alkyl ether acetate. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a polymer having a polysiloxane chain in a side chain that can be used for rust prevention of metal products and the like, a method for producing the same, and a side chain useful as an intermediate raw material for a polymer having a polysiloxane chain in the side chain. The present invention relates to a polymer having a hydrolyzable silyl group and a production method thereof, and a surface-coated metal obtained by coating a metal surface with a polymer having a polysiloxane chain in the side chain and a production method thereof.

  As a means for coating the surface of a metal such as gold, silver, copper, or an alloy thereof for the purpose of rust prevention or the like, coating with a hybrid polymer that is an organic-inorganic composite has been proposed. As such a hybrid polymer, for example, an alkoxysilane having a terminal polymerizable group such as a vinyl group or a (meth) acryloyl group is polymerized by addition polymerization, and a polymer having a silanol group or an alkoxysilyl group in the side chain is obtained. A vinyl polymer having a polysiloxane chain in a side chain obtained by synthesizing and then subjecting this polymer and an alkoxysilane compound to hydrolysis / dehydration condensation reaction is known.

  The metal coated on the surface by such a hybrid polymer does not impair the color of the base metal due to the transparency of the organic polymer and inorganic polymer, and the flexibility of the organic polymer causes expansion and contraction associated with heating and cooling during the film formation process. It has the advantage that it is durable and has excellent friction resistance due to the hardness of the inorganic polymer. However, the adhesion of the coated hybrid polymer is still insufficient, and there is a disadvantage that the film of the hybrid polymer is easily peeled off, particularly when the surface is coated on a noble metal surface on which an oxide layer is difficult to be formed.

  As a technique for solving the above disadvantages without losing the advantages of the hybrid polymer, Japanese Patent Application Laid-Open No. 2004-26939 proposes introducing a thiol group at a terminal of a part of the inorganic polymer portion of the hybrid polymer. Yes.

JP 2004-26939 A

However, according to the study of the present inventors, when the formation of the organic polymer chain is carried out using azobisisobutyronitrile (AIBN) as a polymerization initiator as in the method described in the above-mentioned literature, the resulting hybrid polymer When a silver surface is coated, the coating may appear light yellow.
Accordingly, an object of the present invention is to provide a colorless and transparent surface coating film that is excellent in corrosion resistance, friction resistance, water resistance, solvent resistance, light resistance, and low temperature curability when a metal surface is coated. An object of the present invention is to provide a polymer having a polysiloxane chain in the side chain and an efficient production method thereof.
Another object of the present invention is to provide a polymer having a hydrolyzable silyl group in the side chain useful as an intermediate raw material for the polymer having a polysiloxane chain in the side chain, and an efficient production method thereof. is there.
Still another object of the present invention is to provide a surface-coated metal having excellent corrosion resistance and friction resistance and having a beautiful appearance without coloring or discoloration on the surface coating, and an efficient production method thereof.

  As a result of intensive studies, the present inventors synthesized a hybrid polymer using a polymer obtained by addition polymerization of an unsaturated carboxylic acid ester having a hydrolyzable silicon atom-containing group in the presence of an azo radical polymerization initiator. When the hybrid polymer is coated on the metal surface, the coating is colored or discolored. This is because the decomposition product (residue) of the azo radical polymerization initiator is chemically changed by heat, light, or reaction with other components. This is presumed to be caused by the addition polymerization of an unsaturated carboxylic acid ester having a hydrolyzable silicon atom-containing group in a mixed solvent comprising a combination of specific solvents in the presence of a non-azo radical polymerization initiator. The polymerization reaction proceeds smoothly to obtain a colorless polymer, and the polymer thus obtained and the alkoxysilane compound When subjected to water splitting / dehydration condensation reaction, a hybrid polymer having a curing temperature of 200 ° C. or less can be obtained. When this hybrid polymer is coated on a metal surface, corrosion resistance, friction resistance, water resistance, solvent resistance, and light resistance are improved. In addition to being excellent, the inventors have obtained knowledge that a colorless and transparent surface coating film without coloring or discoloration can be obtained. The present invention has been completed based on these findings.

（式中、Ｒ¹は水素原子又は炭素数１〜３のアルキル基、Ｒ²は炭素数２〜６のアルキレン基、Ｒ³及びＲ⁴は、同一又は異なって、炭素数１〜３のアルキル基を示す。ｊは１〜３の整数である。Ｒ³及びＲ⁴は、それぞれ、複数個存在する場合、それらは同一であっても異なっていてもよい）
で表される加水分解性シリル基を有する不飽和カルボン酸エステルを、非アゾ系ラジカル重合開始剤の存在下、Ｃ_2-4アルキレングリコールモノＣ_1-3アルキルエーテルとＣ_2-4アルキレングリコールモノＣ_1-3アルキルエーテルアセテートとの混合溶媒中で付加重合させることを特徴とする側鎖に加水分解性シリル基を有する重合体の製造方法を提供する。 That is, the present invention provides the following formula (I)

Wherein R ¹ is a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, R ² is an alkylene group having 2 to 6 carbon atoms, and R ³ and R ⁴ are the same or different and are alkyl having 1 to 3 carbon atoms. J represents an integer of 1 to ^{3. When} a plurality of R ³ and R ⁴ are present, they may be the same or different.
In the presence of a non-azo radical polymerization initiator, C _2-4 alkylene glycol mono C _1-3 alkyl ether and C _2-4 alkylene glycol mono Provided is a method for producing a polymer having a hydrolyzable silyl group in a side chain, which is characterized by addition polymerization in a mixed solvent with a C _1-3 alkyl ether acetate.

  In this production method, a peroxide radical polymerization initiator can be used as the non-azo radical polymerization initiator.

  The present invention also provides a polymer having a hydrolyzable silyl group in the side chain obtained by the above production method.

（式中、Ｒ⁵及びＲ⁶は、同一又は異なって、炭素数１〜３のアルキル基を示す。ｋは２〜４の整数である。Ｒ⁵及びＲ⁶は、それぞれ、複数個存在する場合、それらは同一であっても異なっていてもよい）
で表されるアルコキシシラン化合物、又は前記式（II）で表される化合物及び下記式（III）

（式中、Ｒ⁷及びＲ⁹は、同一又は異なって、炭素数１〜３のアルキル基、Ｒ⁸は炭素数２〜６のアルキレン基を示す。ｍは１〜３の整数である。Ｒ⁷及びＲ⁹は、それぞれ、複数個存在する場合、それらは同一であっても異なっていてもよい）
で表されるメルカプト基を有するアルコキシシラン化合物を、加水分解・脱水縮合反応に付すことを特徴とする側鎖にポリシロキサン鎖を有する重合体の製造方法を提供する。 The present invention further includes a polymer having a hydrolyzable silyl group in the side chain, and the following formula (II):

(In the formula, R ⁵ and R ⁶ are the same or different and each represents an alkyl group having 1 to 3 carbon atoms. K is an integer of 2 to 4. There are a plurality of R ⁵ and R ⁶ , respectively. They may be the same or different)
Or a compound represented by the above formula (II) and the following formula (III)

(In formula, R < ⁷ > and R <^9> are the same or different, and a C1-C3 alkyl group, R < ⁸ > shows a C2-C6 alkylene group. M is an integer of 1-3. R ⁷ and R ⁹ may each be the same or different when there are a plurality of R ⁹ and R ⁹ )
The production method of the polymer which has a polysiloxane chain in the side chain characterized by attaching | subjecting the alkoxysilane compound which has a mercapto group represented by this to hydrolysis and a dehydration condensation reaction is provided.

  The present invention further provides a polymer having a polysiloxane chain in the side chain obtained by the production method.

  The present invention also provides a surface-coated metal obtained by coating the metal surface with a polymer having a polysiloxane chain in the side chain.

  The present invention further provides a method for producing a surface-coated metal, wherein a solution containing a polymer having a polysiloxane chain in the side chain is applied to a metal.

  The surface-coated metal of the present invention is excellent in corrosion resistance and friction resistance, and the surface coating is not colored or discolored and has a beautiful appearance. According to the method for producing a surface-coated metal of the present invention, such a surface-coated metal can be produced industrially efficiently. Further, according to the present invention, a polymer having a polysiloxane chain in the side chain, which is excellent in corrosion resistance, friction resistance, water resistance, solvent resistance, and light resistance and can form a surface coating film without coloring or discoloration. A production method thereof, a polymer having a hydrolyzable silyl group in a side chain useful as an intermediate raw material of a polymer having a polysiloxane chain in the side chain, and a production method thereof are provided.

[Production of polymer having hydrolyzable silyl group in side chain]
In the method for producing a polymer having a hydrolyzable silyl group in the side chain of the present invention, an unsaturated carboxylic acid ester having a hydrolyzable silyl group represented by the formula (I) is converted into a non-azo radical polymerization initiator. In the presence of C _2-4 alkylene glycol mono-C _1-3 alkyl ether and C _2-4 alkylene glycol mono-C _1-3 alkyl ether acetate in a mixed solvent, and the side chain is hydrolyzable silyl A polymer having groups is obtained.

In formula (I), R ¹ is a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, R ² is an alkylene group having 2 to 6 carbon atoms, and R ³ and R ⁴ are the same or different and have 1 to 3 carbon atoms. Represents an alkyl group. j is an integer of 1 to 3. When a plurality of R ³ and R ⁴ are present, they may be the same or different.

Examples of the alkyl group having 1 to 3 carbon atoms for R ¹ include methyl, ethyl, propyl, and isopropyl groups. R ¹ is preferably a hydrogen atom or a methyl group, particularly preferably a methyl group. Examples of the alkylene group having 2 to 6 carbon atoms in R ² include linear or branched alkylene groups such as ethylene, trimethylene, propylene, tetramethylene, pentamethylene, and hexamethylene groups. R ² is preferably an alkylene group having 3 to 5 carbon atoms, and particularly preferably a trimethylene group (—CH ₂ CH ₂ CH ₂ —). Examples of the alkyl group having 1 to 3 carbon atoms in R ³ and R ⁴ include methyl, ethyl, propyl, and isopropyl groups. R ³ and R ⁴ are preferably a methyl group or an ethyl group, and particularly preferably a methyl group. j is particularly preferably 2.

  Representative examples of the compound represented by the formula (I) include γ-methacryloxypropyldimethoxymethylsilane, γ-methacryloxypropylmethoxydimethylsilane, γ-methacryloxypropyltrimethoxysilane, and γ-methacryloxypropyldiethoxy. Examples include methylsilane and γ-methacryloxypropyldipropylmethylsilane. Among these, γ-methacryloxypropyldimethoxymethylsilane is particularly preferable.

  In the addition polymerization reaction, a non-azo radical polymerization initiator is used as a polymerization initiator in order to prevent the coating from being colored or discolored by the hybrid polymer. As the non-azo radical polymerization initiator, any polymerization initiator having no azo group in the molecule may be used. For example, di-t-butyl peroxide, 2,5-dimethyl-2,5-bis (t- Dialkyl peroxides such as butylperoxy) hexane; hydroperoxides such as p-menthane hydroperoxide, t-hexyl hydroperoxide, t-butyl hydroperoxide; ketone peroxides such as methyl ethyl ketone peroxide and cyclohexanone peroxide Oxides; Peroxyketals such as 1,1-bis (t-hexylperoxy) -3,3,5-trimethylcyclohexane; Diacyl such as isobutyryl peroxide and 3,5,5-trimethylhexanoyl peroxide Peroxides; 1,1 Peroxyesters such as 3,3-tetramethylbutylperoxyneodecanate, t-hexylperoxyneodecanate, t-butylperoxyneodecanate; peroxy such as di-n-propylperoxydicarbonate Benzoins such as benzoin and benzoin methyl ether; acetophenones such as trichloroacetophenone and 2,2-diethoxyacetophenone; propiophenones such as 2-hydroxy-2-methylpropiophenone; benzophenone and methylbenzophenone Benzophenones such as thioxanthones such as 2-chlorothioxanthone. Among these, peroxide radical polymerization initiators such as dialkyl peroxides, hydroperoxides, ketone peroxides, peroxyketals, diacyl peroxides, peroxyesters, peroxydicarbonates, etc. In particular, dialkyl peroxides such as di-t-butyl peroxide are preferable.

In the present invention, a mixed solvent of C _2-4 alkylene glycol mono C _1-3 alkyl ether and C _2-4 alkylene glycol mono C _1-3 alkyl ether acetate is used as a reaction solvent (polymerization solvent). In general, the decomposition temperature of a non-azo radical polymerization initiator (the temperature at which it functions as an initiator) is higher than that of an azo radical polymerization initiator, but the mixed solvent has a high boiling point. Thus, the temperature can be increased to the decomposition temperature, and addition polymerization can proceed smoothly. Moreover, since this mixed solvent is generally water-soluble, it can be used for the next hydrolysis / dehydration condensation reaction in a state dissolved in the solvent without isolating the reaction product. Furthermore, when this mixed solvent is used as a polymerization solvent, a colorless hydrolyzable silyl group-containing polymer can be obtained, and when a hybrid polymer is produced using this polymer, a surface coating film without coloring or discoloration can be formed. .

Examples of the C _2-4 alkylene glycol mono C _1-3 alkyl ether include ethylene glycol monomethyl ether, ethylene glycol monoethyl ether (= ethoxyethanol), ethylene glycol monopropyl ether, 1,3-propanediol monomethyl ether, 1 , 3-propanediol monoethyl ether, 1,3-propanediol monopropyl ether, 1,2-propanediol monomethyl ether (= propylene glycol monomethyl ether), 1,2-propanediol monoethyl ether, 1,2-propane Diol monopropyl ether, 1,4-butanediol monomethyl ether, 1,4-butanediol monoethyl ether, 1,3-butanediol monomethyl ether, 1,3-butanediol Such as monoethyl ether. These solvents can be used alone or in combination of two or more. Among these, 1,2-propanediol monomethyl ether (= propylene glycol monomethyl ether) is particularly preferable.

Examples of the C _2-4 alkylene glycol mono C _1-3 alkyl ether acetate include ethylene glycol monomethyl ether acetate, ethylene glycol monoethyl ether acetate, ethylene glycol monopropyl ether acetate, 1,3-propanediol monomethyl ether acetate, 1 , 3-propanediol monoethyl ether acetate, 1,3-propanediol monopropyl ether acetate, 1,2-propanediol monomethyl ether acetate, 1,2-propanediol monoethyl ether acetate, 1,2-propanediol monopropyl Ether acetate, 1,4-butanediol monomethyl ether acetate, 1,4-butanediol monoethyl ether acetate, 1,3-butane Emissions diol monomethyl ether acetate, and 1,3-butanediol monoethyl ether acetate. These solvents can be used alone or in combination of two or more. Among these, 1,2-propanediol monomethyl ether acetate (1,2-propanediol-2-methyl ether-1-acetate, 1,2-propanediol-1-methyl ether-2-acetate), 1,3 -Butanediol monomethyl ether acetate (1,3-butanediol-3-methyl ether-1-acetate, 1,3-butanediol-1-methyl ether-3-acetate), especially 1,3-butanediol monomethyl Ether acetate (especially 1,3-butanediol-3-methyl ether-1-acetate) is preferred.

The mixing ratio of C _2-4 alkylene glycol mono C _1-3 alkyl ether and C _2-4 alkylene glycol mono C _1-3 alkyl ether acetate is the type of compound represented by formula (I), the type of the solvent, etc. The former / the latter (volume ratio; 20 ° C.) = 60/40 to 90/10 is preferable from the viewpoint of the physical properties of the polymer to be produced and the finally obtained hybrid polymer, and the former / the latter. (Volume ratio; 20 ° C.) = 70/30 to 80/20 is particularly preferable. If the value of the former / the latter (volume ratio; 20 ° C.) is too small, it varies depending on the combination of solvents used, but in a chromatogram obtained by GPC (gel permeation chromatography), a low molecular weight region (for example, molecular weight 2000) ~ 8000) and two peaks (peaks) in a high molecular weight region (for example, a molecular weight of 35,000 to 60000) may be observed (a multimodal polymer is likely to be formed). Such a polymer having a polysiloxane chain in a side chain obtained by reacting a polymer having a hydrolyzable silyl group in a multimodal side chain with an alkoxysilane compound tends to have a high curing temperature (for example, 200 ° C.). Temperature), and it tends to be water-insoluble. On the other hand, if the value of the former / the latter (weight ratio) is too large, gelation tends to occur when a polymer having a hydrolyzable silyl group in the side chain obtained by polymerization is reacted with an alkoxysilane compound.

The reaction solvent may contain a small amount of another solvent in addition to the C _2-4 alkylene glycol mono C _1-3 alkyl ether and the C _2-4 alkylene glycol mono C _1-3 alkyl ether acetate. The total amount of the C _2-4 alkylene glycol mono C _1-3 alkyl ether and the C _2-4 alkylene glycol mono C _1-3 alkyl ether acetate is usually 50% by weight or more of the total reaction solvent, preferably the total reaction solvent. 70% by weight or more, more preferably 90% by weight or more of the total reaction solvent, and the reaction solvent is substantially the above C _2-4 alkylene glycol mono C _1-3 alkyl ether and C _2-4 alkylene glycol mono C _{1- It} may be composed of only ₃ alkyl ether acetates.

  The polymerization temperature varies depending on the decomposition temperature of the polymerization initiator and the boiling point of the solvent, but is usually 50 to 200 ° C, preferably 100 to 160 ° C. If the polymerization temperature is too low, it takes time for the polymerization, and conversely if it is too high, it tends to boil violently.

（式中、Ｒ¹、Ｒ²、Ｒ³、Ｒ⁴、ｊは前記に同じ）
で表される側鎖に加水分解性シリル基を有する重合体が生成する。重合溶媒としてＣ_2-4アルキレングリコールモノＣ_1-3アルキルエーテルとＣ_2-4アルキレングリコールモノＣ_1-3アルキルエーテルアセテートの混合溶媒を用いると、ほぼ単峰性（ショルダーを有する場合も含める）で且つ数万の重量平均分子量を有するポリマーを得ることができる。例えば、生成するポリマーの重量平均分子量は、通常１００００〜５００００であり、好ましくは１２０００〜３００００である。重量平均分子量が小さすぎる場合は粘度が低く硬化しにくく、逆に大きすぎる場合は粘度が高く塗布前に硬化しやすい。分子量分布（重量平均分子量Ｍｗ／数平均分子量Ｍｎ）は、例えば１．０〜４、好ましくは１．０〜２．５程度である。 By the above polymerization reaction, the following formula (IV)

(Wherein R ¹ , R ² , R ³ , R ⁴ , j are the same as above)
A polymer having a hydrolyzable silyl group in the side chain represented by When a mixed solvent of C _2-4 alkylene glycol mono C _1-3 alkyl ether and C _2-4 alkylene glycol mono C _1-3 alkyl ether acetate is used as a polymerization solvent, it is almost unimodal (including cases having shoulders) And a polymer having a weight average molecular weight of tens of thousands. For example, the weight average molecular weight of the produced polymer is usually 10,000 to 50,000, preferably 12,000 to 30,000. If the weight average molecular weight is too small, the viscosity is low and difficult to cure, and conversely if too large, the viscosity is high and easy to cure before coating. The molecular weight distribution (weight average molecular weight Mw / number average molecular weight Mn) is, for example, about 1.0 to 4, preferably about 1.0 to 2.5.

  The obtained polymerization solution is subjected to the next reaction by distilling off the solvent as necessary to obtain a solution having a desired concentration. Moreover, what was isolated by the well-known separation-purification means can also be used for the next reaction.

[Production of polymer having polysiloxane chain in side chain]
In the method for producing a polymer having a polysiloxane chain in the side chain of the present invention, a polymer having a hydrolyzable silyl group in the side chain obtained by the above reaction, an alkoxysilane compound represented by the formula (II), Alternatively, the compound represented by the formula (II) and the alkoxysilane compound having a mercapto group represented by the following formula (III) are subjected to hydrolysis / dehydration condensation reaction.

In formula (II), R ⁵ and R ⁶ are the same or different and represent an alkyl group having 1 to 3 carbon atoms. k is an integer of 2-4. When a plurality of R ⁵ and R ⁶ are present, they may be the same or different. In the formula (III), R ⁷ and R ⁹ are the same or different and each represents an alkyl group having 1 to 3 carbon atoms, and R ⁸ represents an alkylene group having 2 to 6 carbon atoms. m is an integer of 1-3. When a plurality of R ⁷ and R ⁹ are present, they may be the same or different.

Examples of the alkyl group having 1 to 3 carbon atoms in R ⁵ , R ⁶ , R ⁷ , and R ⁹ include methyl, ethyl, propyl, and isopropyl groups. R ⁵ is preferably a methyl group or an ethyl group, particularly preferably an ethyl group. As k, 4 is particularly preferable. R ⁷ is preferably a methyl group or an ethyl group, and particularly preferably a methyl group. As m, 3 is particularly preferable.

Examples of the alkylene group having 2 to 6 carbon atoms in R ⁸ include linear or branched alkylene groups such as ethylene, trimethylene, propylene, tetramethylene, pentamethylene, and hexamethylene groups. R ⁸ is preferably an alkylene group having 3 to 5 carbon atoms, and particularly preferably a trimethylene group (—CH ₂ CH ₂ CH ₂ —).

  Representative examples of the alkoxysilane compound represented by the formula (II) include, for example, dimethoxydimethylsilane, trimethoxymethylsilane, tetramethoxysilane, diethoxydimethylsilane, triethoxymethylsilane, tetraethoxysilane, and dipropoxydimethyl. Examples thereof include silane, tripropoxymethylsilane, and tetrapropoxysilane. Among these, tetraethoxysilane is particularly preferable.

  Representative examples of the alkoxysilane compound having a mercapto group represented by the formula (III) include, for example, γ-mercaptopropyltrimethoxysilane, γ-mercaptopropyldimethoxymethylsilane, γ-mercaptopropylmethoxydimethylsilane, γ- Mercaptopropyltriethoxysilane, γ-mercaptopropyldiethoxymethylsilane, γ-mercaptopropylethoxydimethylsilane, δ-mercaptobutyltrimethoxysilane, δ-mercaptobutyldimethoxymethylsilane, δ-mercaptobutylmethoxydimethylsilane, δ-mercapto Examples include butyltriethoxysilane, δ-mercaptobutyldiethoxymethylsilane, and δ-mercaptobutylethoxydimethylsilane. Among these, γ-mercaptopropyltrialkoxysilane such as γ-mercaptopropyltrimethoxysilane is preferable.

  The use amount of the alkoxysilane compound represented by the formula (II) is, for example, 0.05 mol with respect to 1 mol of the monomer that forms a polymer having a hydrolyzable silyl group in the side chain represented by the formula (IV). It is about -0.8 mol, preferably about 0.1-0.5 mol. If the amount of the alkoxysilane compound represented by the formula (II) is too small, the friction resistance and the solvent resistance are lowered. Conversely, if the amount is too large, the viscosity is lowered and the film is easily peeled off. .

  The amount of the alkoxysilane compound having a mercapto group represented by the formula (III) is generally 0 with respect to 1 mol of the polymer monomer having a hydrolyzable silyl group in the side chain represented by the formula (IV). 0.001 to 0.1 mol, preferably 0.005 to 0.09 mol. If the amount of the alkoxysilane compound having a mercapto group represented by the formula (III) is too small, the resulting hybrid polymer is easily peeled off when it is coated on a metal surface (especially a noble metal surface). If it is too much, it tends to cause coloring or discoloration.

  The abundance ratio of sulfur atoms (S) to silicon atoms (Si) in the resulting polymer having a polysiloxane chain is preferably 0.3 to 10 mol%, more preferably 0.5 to 10 mol%, particularly Preferably it is 0.5-4.8 mol%. You may adjust the usage-amount of the alkoxysilane compound which has a mercapto group represented by Formula (III) so that it may become such a ratio.

  A known method can be used for the hydrolysis / dehydration condensation reaction. For example, a solution of a polymer having a hydrolyzable silyl group in the side chain represented by formula (IV), an alkoxysilane compound represented by formula (II), or a compound and formula represented by formula (II) Hydrolysis / dehydration condensation reaction can be carried out by adding an alkoxysilane compound having a mercapto group represented by (III) and reacting by adding an aqueous solution of acid such as dilute hydrochloric acid dropwise. In addition, when reacting the compound represented by the formula (II) and the alkoxysilane compound having a mercapto group represented by the formula (III), the reaction may be carried out step by step, represented by the formula (II). One of the compound and the alkoxysilane compound having a mercapto group represented by formula (III) may be reacted first, and then the other may be reacted. The acid acts as a catalyst for hydrolysis. As for the usage-amount of the aqueous solution of an acid, reaction equivalent is illustrated, for example. The concentration when dilute hydrochloric acid is used is, for example, about 0.0001 to 0.002N. Examples of the solution of the polymer having a hydrolyzable silyl group in the side chain represented by the formula (IV) subjected to the reaction include, for example, a reaction solution after the polymerization reaction of the compound represented by the formula (I) or its concentration A liquid can be used.

  The reaction temperature in the hydrolysis / dehydration condensation reaction is, for example, 40 to 100 ° C., preferably 50 to 80 ° C.

（式中、Ｒ¹、Ｒ²は前記に同じ）
で表される側鎖にポリシロキサン鎖を有する重合体（ハイブリッドポリマー）が生成する。式（Ｖ）中のケイ素原子の三つの結合手のうち、少なくとも一つには酸素原子が結合しており、残りの結合手には炭素数１〜３のアルキル基が結合している。好ましくは、ケイ素原子には二つの酸素原子が結合し、残りの一つの結合手にはメチル基が結合している。ケイ素原子に結合した酸素原子は他のケイ素原子、すなわち、式（Ｖ）、式（II）又は式（III）の化合物のケイ素原子とシロキサン結合を形成しているか、又は加水分解により水素原子と共に末端水酸基を形成している。該末端水酸基は、水素結合可能な化学種（例えば、他の部分構造中の末端水酸基、重合体中に取り込んだ溶媒分子、金属表面の吸着水等）と水素結合を形成しうる。 A siloxane bond is formed by the above reaction, and the following formula (V)

(Wherein R ¹ and R ² are the same as above)
A polymer (hybrid polymer) having a polysiloxane chain in the side chain represented by Of the three bonds of the silicon atom in the formula (V), an oxygen atom is bonded to at least one bond, and an alkyl group having 1 to 3 carbon atoms is bonded to the remaining bond. Preferably, two oxygen atoms are bonded to the silicon atom, and a methyl group is bonded to the remaining one bond. The oxygen atom bonded to the silicon atom forms a siloxane bond with another silicon atom, that is, the silicon atom of the compound of formula (V), formula (II) or formula (III), or together with the hydrogen atom by hydrolysis A terminal hydroxyl group is formed. The terminal hydroxyl groups can form hydrogen bonds with chemical species capable of hydrogen bonding (for example, terminal hydroxyl groups in other partial structures, solvent molecules incorporated into the polymer, adsorbed water on the metal surface, etc.).

  According to the method of the present invention, a colorless and transparent polymer having a weight average molecular weight of tens of thousands and having a polysiloxane chain in the side chain can be obtained. The film-forming temperature of the polymer thus obtained is, for example, 100 to 180 ° C, preferably 110 to 160 ° C, particularly preferably 130 to 150 ° C. If the film forming temperature is too low, it is disadvantageous in that it takes time to cure. Conversely, if the film forming temperature is too high, the film tends to peel off.

  The obtained reaction solution is used as a coating solution for metal coating after removing contaminants from the atmosphere by filtration or adjusting the viscosity as necessary. The viscosity of the coating solution can be appropriately selected in consideration of the coating method, the required film thickness, and workability, but is generally preferably 5 to 50 cP (0.005 to 0.05 Pa · s), particularly in the spray method. The range of 10-30 cP (0.01-0.03 Pa.s) is preferable.

[Manufacture of surface coated metal]
In the method for producing a surface-coated metal according to the present invention, a solution containing a polymer having a polysiloxane chain in the side chain obtained above is applied to a metal. Examples of the metal include, but are not limited to, gold, silver, copper, and alloys. According to the present invention, the hybrid polymer has a mercapto group and can be directly chemically bonded to the metal. Even if it is a noble metal such as gold or silver, a strong film can be obtained. It does not specifically limit as a method to apply to a metal, A well-known method is employable. For example, a dipping method, a spray method, a spin coater method, etc. are mentioned. A solution containing a polymer having a polysiloxane chain in the side chain is applied to a metal, and then heated and dried, thereby causing the condensation reaction to proceed completely and removing the solvent to form a hard coating. The thickness of the coating can be appropriately selected according to the purpose, but according to the present invention, even a thin coating of 1 to 10 μm, particularly 1 to 5 μm, has an advantage that it has a sufficient metal rust prevention function.

  In the present invention, a polymer obtained by addition polymerization of an unsaturated carboxylic acid ester having a hydrolyzable silyl group in a mixed solvent comprising a combination of specific solvents in the presence of a non-azo radical polymerization initiator, Since the hybrid polymer obtained by subjecting the silane compound to hydrolysis / dehydration condensation is coated on the metal surface, it has a beautiful appearance with no coloration or discoloration on the surface coating, and excellent corrosion resistance and friction resistance. A surface-coated metal is obtained.

EXAMPLES Hereinafter, although this invention is demonstrated in detail based on an Example, this invention is not limited at all by these Examples. In addition, the analysis conditions of GPC (gel permeation chromatography) are as follows.
[GPC analysis conditions]
Equipment: SHIMADZU CBM-10A (controller), RID-10A (detector), CTO-10A (oven), SIL-10A (autoinjector), LC-10AT (pump), DGU- 12A (Degasser)
・ Column: Showa Denko Co., Ltd., Shodex KF-803L, KF-804L, KF-G (guard column) connected in series ・ Sample: 0.2 mL of polymer solution in 1 mL of THF (tetrahydrofuran) Dissolved ・ Injection volume: 100 μL
・ Oven temperature: 40 ℃
-Mobile phase: THF
-Mobile phase flow rate: 1 mL / min

[Corrosion resistance test]
The performance of the coating films obtained in the examples was evaluated by a corrosion resistance test. Specifically, the coated metal was allowed to stand for 1 month at room temperature on the inner plate of a desiccator containing a 5% by weight aqueous solution of sodium sulfide.

[Environmental cycle test]
The performance of the coating obtained in the examples was evaluated by an environmental cycle test in accordance with JIS-K5600. Specifically, the coated metal is put into a constant temperature and humidity machine, and the environment of 50 ° C. and 90% RH for 18 hours, followed by −20 ° C. for 3 hours and further 25 ° C. and 50% RH for 3 hours is repeated 10 times. It was.

[Pencil hardness test]
The performance of the coating films obtained in the examples was evaluated by a pencil scratch test in accordance with JIS-K5400. Specifically, a pencil of each hardness was applied to the coated metal at 45 °, pressed as hard as possible to the extent that the core did not break, and pulled forward at a uniform speed (change the position for each pencil). 5 times). The highest hardness among the pencils in which the tearing of the coating reaching the underlying metal was 1 or less out of 5 scratches was used as an index of the strength of the coating.

Example 1
150.0 g of γ-methacryloxypropyldimethoxymethylsilane and 4.73 g of di-t-butyl peroxide (polymerization initiator) were added to 1,2-propanediol monomethyl ether (1,2-propanediol-1-methyl ether- 2-ol) 580.5 mL and 1,3-butanediol-3-methyl ether-1-acetate (= 3-methoxybutyl acetate) 193.5 mL mixed solvent [former / latter (volume ratio; 20 ° C.) = 75 / 25] and radical polymerization was carried out by stirring at 124 ° C. for 3 hours in a nitrogen gas atmosphere. The obtained polymerization solution was concentrated under reduced pressure (32 hPa) at 40 to 50 ° C. When the molecular weight of the produced polymer was measured by GPC, the peak was unimodal (slightly shouldered), the weight average molecular weight was 12,000, and the number average molecular weight was 11500.
Tetraethoxysilane (4.81 mL) and γ-mercaptopropyltrimethoxysilane (0.20 mL) were added to 195.0 mL of the obtained concentrated liquid (polymer concentration: about 1.0 mol / L) and dissolved therein. .57 mL was slowly added dropwise with stirring, followed by stirring at 60 ° C. for 3 hours. The obtained reaction mixture was filtered using a filter plate having a pore size of 5 to 10 μm to obtain a colorless and transparent hybrid polymer solution. The viscosity of the hybrid polymer solution was 11.2 cP (0.0112 Pa · s).
The hybrid polymer solution was applied to a silver medal (diameter 27 to 40 mm, thickness 2 to 3 mm) having a purity of 99.9% by a spray method. Thereafter, the film was dried in a warm air dryer at 130 ° C. for 30 minutes to form a colorless and transparent film on the silver surface.
When the performance of the coating was evaluated by a corrosion resistance test and an environmental cycle test, no deterioration such as discoloration or peeling was observed. Moreover, 4H was shown as a result of evaluating the performance of a film by a pencil hardness test.

Example 2
150.0 g of γ-methacryloxypropyldimethoxymethylsilane and 4.73 g of di-t-butyl peroxide (polymerization initiator) were added to 1,2-propanediol monomethyl ether (1,2-propanediol-1-methyl ether- 2-ol) 580.5 mL and 1,3-butanediol-3-methyl ether-1-acetate (= 3-methoxybutyl acetate) 193.5 mL mixed solvent [former / latter (volume ratio; 20 ° C.) = 75 / 25] and radical polymerization was carried out by stirring at 124 ° C. for 3 hours in a nitrogen gas atmosphere. The obtained polymerization solution was concentrated under reduced pressure (32 hPa) at 40 to 50 ° C. When the molecular weight of the produced polymer was measured by GPC, the peak was unimodal (slightly shouldered), the weight average molecular weight was 12,000, and the number average molecular weight was 11500.
Tetraethoxysilane (21.92 mL) and γ-mercaptopropyltrimethoxysilane (0.23 mL) are added to 150.0 mL of the obtained concentrated liquid (polymer concentration: about 1.0 mol / L) and dissolved therein. .42 mL was slowly added dropwise with stirring, followed by stirring at 60 ° C. for 3 hours. The obtained reaction mixture was filtered using a filter plate having a pore size of 5 to 10 μm to obtain a colorless and transparent hybrid polymer solution. The viscosity of the hybrid polymer solution was 18.5 cP (0.0185 Pa · s).
The hybrid polymer solution was applied to a silver medal (diameter 27 to 40 mm, thickness 2 to 3 mm) having a purity of 99.9% by a spray method. Thereafter, the film was dried in a warm air dryer at 130 ° C. for 30 minutes to form a colorless and transparent film on the silver surface.
When the performance of the coating was evaluated by a corrosion resistance test and an environmental cycle test, no deterioration such as discoloration or peeling was observed. Moreover, 6H was shown as a result of evaluating the performance of a film by the pencil hardness test.

Example 3
19.0 g of γ-methacryloxypropyldimethoxymethylsilane and 1.20 g of di-t-butyl peroxide (polymerization initiator) were added to 1,2-propanediol monomethyl ether (1,2-propanediol-1-methyl ether- 2-ol) 63.7 mL, 1,3-butanediol-3-methyl ether-1-acetate (= 3-methoxybutyl acetate) 24.5 mL and ethoxyethanol 9.8 mL mixed solvent [volume ratio of the three ( 20 ° C. 9): 65/25/10] and stirred in a nitrogen gas atmosphere at 119 ° C. for 2 hours and 20 minutes for radical polymerization. The obtained polymerization solution was concentrated under reduced pressure (32 hPa) at 40 to 50 ° C. When the molecular weight of the produced polymer was measured by GPC, the peak had a slightly broad shape with a shoulder, the weight average molecular weight was 17,900, and the number average molecular weight was 5,500.
To 100.5 mL of the obtained concentrated liquid (polymer concentration: about 0.8 mol / L), 1.82 mL of tetraethoxysilane and 0.08 mL of γ-mercaptopropyltrimethoxysilane were added and dissolved, and 0.001N hydrochloric acid 3 .55 mL was slowly added dropwise with stirring, followed by stirring at 60 ° C. for 5 hours. The obtained reaction mixture was filtered using a filter plate having a pore size of 5 to 10 μm to obtain a colorless and transparent hybrid polymer solution. The viscosity of the hybrid polymer solution was 15.1 cP (0.0151 Pa · s).
The hybrid polymer solution was applied to a silver medal (diameter 27 to 40 mm, thickness 2 to 3 mm) having a purity of 99.9% by a spray method. Then, a colorless transparent film was formed on the silver surface by drying in a hot air dryer at 150 ° C. for 30 minutes.
When the performance of the coating was evaluated by a corrosion resistance test and an environmental cycle test, no deterioration such as discoloration or peeling was observed. Moreover, 4H was shown as a result of evaluating the performance of a film by a pencil hardness test.

Comparative Example 1
76.0 g of γ-methacryloyloxypropyldimethoxymethylsilane and 2.4 g of di-t-butyl peroxide (polymerization initiator) were mixed with 294.0 mL of ethoxyethanol and 98.0 mL of tetrahydrofuran [the former / the latter (volume ratio; 20 ° C.) = 75/25] and stirred at 114 ° C. for 6 hours in a nitrogen gas atmosphere for radical polymerization. The obtained polymerization solution was concentrated under reduced pressure (32 hPa) at 40 to 50 ° C. When the molecular weight of the produced polymer was measured by GPC, the peak was unimodal, the weight average molecular weight was 65,000, and the number average molecular weight was 23,000.
Tetraethoxysilane 1.48 mL and γ-mercaptopropyltrimethoxysilane 0.07 mL are added to 65.0 mL of the obtained concentrated liquid (polymer concentration: about 1.0 mol / L) and dissolved therein. .88 mL was slowly added dropwise with stirring, followed by stirring at 60 ° C. for 5 hours. This hybrid polymer solution gelled during heating.

Claims (7)

Formula (I)

Wherein R ¹ is a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, R ² is an alkylene group having 2 to 6 carbon atoms, and R ³ and R ⁴ are the same or different and are alkyl having 1 to 3 carbon atoms. J represents an integer of 1 to ^{3. When} a plurality of R ³ and R ⁴ are present, they may be the same or different.
In the presence of a non-azo radical polymerization initiator, C _2-4 alkylene glycol mono C _1-3 alkyl ether and C _2-4 alkylene glycol mono A method for producing a polymer having a hydrolyzable silyl group in a side chain, wherein addition polymerization is carried out in a mixed solvent with a C _1-3 alkyl ether acetate.   The method for producing a polymer having a hydrolyzable silyl group in a side chain according to claim 1, wherein a peroxide radical polymerization initiator is used as the non-azo radical polymerization initiator.   The polymer which has a hydrolyzable silyl group in the side chain obtained by the manufacturing method of Claim 1 or 2. A polymer having a hydrolyzable silyl group in the side chain according to claim 3, and the following formula (II):

(In the formula, R ⁵ and R ⁶ are the same or different and each represents an alkyl group having 1 to 3 carbon atoms. K is an integer of 2 to 4. There are a plurality of R ⁵ and R ⁶ , respectively. They may be the same or different)
Or a compound represented by the above formula (II) and the following formula (III)

(In formula, R < ⁷ > and R <^9> are the same or different, and a C1-C3 alkyl group, R < ⁸ > shows a C2-C6 alkylene group. M is an integer of 1-3. R ⁷ and R ⁹ may each be the same or different when there are a plurality of R ⁹ and R ⁹ )
A process for producing a polymer having a polysiloxane chain in the side chain, wherein the alkoxysilane compound having a mercapto group represented by the formula is subjected to hydrolysis / dehydration condensation reaction.   The polymer which has a polysiloxane chain in the side chain obtained by the manufacturing method of Claim 4.   A surface-coated metal obtained by coating a metal surface with the polymer having a polysiloxane chain in the side chain according to claim 5.   A method for producing a surface-coated metal, comprising applying a solution containing a polymer having a polysiloxane chain in a side chain according to claim 5 to a metal.