JP2014009304A - Inorganic clear coating composition and method for forming double-layer coating film by using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an inorganic clear coating composition having durability to a combined action of alkali and ultraviolet light and capable to keep film coating functions for a long time even when it is used for base materials such as ceramic building materials or slate building materials for a roof.SOLUTION: An inorganic clear coating composition contains (a) a silanol group-containing polyorganosiloxane represented by a general formula (I), (b) a silane coupling agent represented by a general formula (II), (c) a curing catalyst selected from the group consisting of a tertiary amine compound and a tin-containing compound, and (d) an inorganic ultraviolet absorber which is one or more kinds of compounds selected from the group consisting of titanium oxide, zinc oxide, tin oxide and cerium oxide.

Description

  The present invention relates to a highly weather-resistant coating material for building materials and a multilayer coating film using the same. More specifically, the present invention relates to a highly weather-resistant inorganic clear coating composition used when forming a multilayer coating film on a building material substrate used outdoors, which is an object to be coated.

  Outdoor coating films for building materials are always exposed to harsh environments, and in recent years, the environment has been further deteriorated due to acid rain and an increase in ultraviolet rays accompanying ozone layer destruction. In addition, long-term durability of several decades is required due to market demand. That is, a coating composition that can maintain coating performance such as weather resistance and chemical resistance over a long period of time in a harsh environment is awaited.

  Examples of paints that are said to have high durability include fluorine paints, acrylic silicone paints, and inorganic paints. However, fluorine paints and acrylic silicone paints are not satisfactory as those having the above-mentioned coating film performance.

  Therefore, attempts have been made to increase durability by using an inorganic paint as a clear paint. For example, JP-A-10-60377 (Patent Document 1) discloses a silanol-containing polyorganosiloxane, a glycidoxypropyl group-containing silane, a silane mixture having two hydrolyzable groups, an amino group-containing alkoxysilane, and a curing catalyst. Disclosed is a coating composition containing

  JP 2000-239608 A (Patent Document 2) discloses a coating composition containing an organosilane, a polyorganosiloxane having a silanol group, silica, a curing catalyst, and further containing a hydrolyzable organosiloxane. It is disclosed that a film having excellent cracking properties can be formed.

Japanese Patent Laid-Open No. 10-60377 JP 2000-239608 A

  As a result of diligent research, the inventors have found that cracks on this inorganic clear coating film are caused by the combined action of alkali components and ultraviolet rays that elute when the object to be coated, which is a base material for building materials, comes into contact with water. It was determined that the deterioration was caused.

  However, the coating composition disclosed in Patent Document 1 does not have the long-term durability that the market demands for the quality of the coating film because cracks occur when used for a long time. Moreover, although the coating composition disclosed in Patent Document 2 has been studied for the durability of the coating film formed on the aluminum plate, the alkaline component is eluted when the base material for building materials comes into contact with water, It did not pay attention to the occurrence of cracks in the coating film due to the combined action with ultraviolet rays, and the weather resistance was insufficient for use as a building material substrate used outdoors.

  The object of the present invention is to provide excellent coating performance as described above, and for a long period of time against the combined action of alkali components and ultraviolet rays that are eluted when the object to be coated and water come into contact with each other. To provide an inorganic clear coating composition that can form a coating film that is less likely to generate and that can maintain various performances of a high coating film for a long period of time, and to provide an inorganic highly weather-resistant clear coating film obtained therefrom. is there.

  The present invention relates to (a) general formula (I):

（式中、Ｒ¹は、同一または異種の置換もしくは非置換の、合計炭素数が１〜８である１価の炭化水素基を示し、Ｘは、酸素原子を介して、同一ポリオルガノシロキサン中または他のポリオルガノシロキサン中の骨格に存在するＳｉと結合するシロキサン構造を示し、ａ^１、ｂ^１およびｃ^１は、ランダムコポリマー中のモル分率を意味し、それぞれ、０．０５≦ａ^１≦０．２５、０≦ｂ^１≦０．２５、０．５０≦ｃ^１≦０．９５およびａ^１＋ｂ^１＋ｃ^１＝１の関係を満たす数である。）で表されるシラノール基含有ポリオルガノシロキサン；
（ｂ）一般式（ＩＩ）：

(In the formula, R ¹ represents the same or different substituted or unsubstituted monovalent hydrocarbon group having 1 to 8 carbon atoms in total, and X represents the same polyorganosiloxane through an oxygen atom. Or a siloxane structure bonded to Si present in the skeleton in another polyorganosiloxane, wherein a ¹ , b ¹ and c ¹ mean the mole fraction in the random copolymer, and each represents 0.05 ≦ a ¹ ≦ 0.25, 0 ≦ b ¹ ≦ 0.25, 0.50 ≦ c ¹ ≦ 0.95 and a number satisfying the relationship of a ¹ + b ¹ + c ¹ = 1.) Organosiloxane;
(B) General formula (II):

（式中、Ｙは合計炭素数が１〜８であり、１価の炭化水素基が１つ以上の反応性官能基により置換されたものであり、上記反応性官能基はグリシジルオキシ基、アミノ基、メルカプト基、ビニル基および（メタ）アクリロイル基よりなる群から選択される１種以上の官能基であり、Ｒ^６はフェニル基または全炭素数が１〜８である１価の炭化水素基、Ｒ^７は全炭素数が１〜４のアルキル基、ｎは０〜２の整数を示す。）で表されるシランカップリング剤；
（ｃ）三級アミン化合物およびスズ含有化合物よりなる群から選択される硬化触媒；および
（ｄ）酸化チタン、酸化亜鉛、酸化錫、酸化セリウムからなる群より選ばれる１種以上の化合物である無機紫外線吸収剤
を含有する、無機クリヤー塗料組成物である。

(In the formula, Y has 1 to 8 carbon atoms in total, a monovalent hydrocarbon group is substituted with one or more reactive functional groups, and the reactive functional groups are glycidyloxy groups, amino 1 or more functional groups selected from the group consisting of a group, a mercapto group, a vinyl group and a (meth) acryloyl group, and R ⁶ is a phenyl group or a monovalent hydrocarbon group having 1 to 8 carbon atoms in total. , R ⁷ is an alkyl group having 1 to 4 carbon atoms, and n is an integer of 0 to 2).
(C) a curing catalyst selected from the group consisting of tertiary amine compounds and tin-containing compounds; and (d) one or more compounds selected from the group consisting of titanium oxide, zinc oxide, tin oxide and cerium oxide. An inorganic clear coating composition containing an ultraviolet absorber.

  Here, the inorganic clear coating composition of the present invention includes, as its embodiment, (a) a silanol group-containing polyorganosiloxane represented by the general formula (I) and (b) a silane cup represented by the general formula (II). It is preferable that solid content mass ratio with a ring agent is (a) :( b) = 90: 10-60: 40.

  In another aspect of the inorganic clear coating composition of the present invention, (a) the silanol group-containing polyorganosiloxane represented by the general formula (I) is represented by the general formula (III):

（式中、Ｒ^２は、同一または異種の置換もしくは非置換の、合計炭素数が１〜８であるアルキル基を示し、Ｘは、酸素原子を介して、同一ポリオルガノシロキサン中または他のポリオルガノシロキサン中の骨格に存在するＳｉと結合するシロキサン構造を示し、ａ^２およびｃ^２は、ランダムコポリマー中のモル分率を意味し、それぞれ、０．０５≦ａ^２≦０．２５、０．７５≦ｃ^２≦０．９５およびａ^２＋ｃ^２＝１の関係を満たす数である。）で表されるシラノール基含有ポリオルガノシロキサンであることが好ましい。

(In the formula, R ² represents the same or different substituted or unsubstituted alkyl group having 1 to 8 carbon atoms in total, and X represents an oxygen atom through the same polyorganosiloxane or other polyalkylene. shows a siloxane structure binds to Si present in the backbone of the organosiloxane, ^{a 2} and ^{c 2} means a molar fraction in the random copolymer, respectively, 0.05 ≦ ^{a 2} ≦ 0.25,0. It is preferably a silanol group-containing polyorganosiloxane represented by the following formula: 75 ≦ c ² ≦ 0.95 and a ² + c ² = 1.

  In another aspect of the inorganic clear coating composition of the present invention, (a) the silanol group-containing polyorganosiloxane represented by the general formula (I) is represented by the general formula (IV):

（式中、Ｒ^３は、同一または異種の置換もしくは非置換の、合計炭素数が１〜８であるアルキル基を示し、Ｘは、酸素原子を介して、同一ポリオルガノシロキサン中または他のポリオルガノシロキサン中の骨格に存在するＳｉと結合するシロキサン構造を示し、ａ^３、ｂ^３およびｃ^３は、ランダムコポリマー中のモル分率を意味し、それぞれ、０．０５≦ａ^３≦０．２５、０．０５≦ｂ^３≦０．２５、０．５０≦ｃ^３≦０．９０およびａ^３＋ｂ^３＋ｃ^３＝１の関係を満たす数である。）で表されるシラノール基含有ポリオルガノシロキサンであることが好ましい。

(In the formula, R ³ represents the same or different substituted or unsubstituted alkyl group having 1 to 8 carbon atoms in total, and X represents an oxygen atom through the same polyorganosiloxane or other polyalkylene. A siloxane structure bonded to Si present in the skeleton in the organosiloxane is shown, and a ³ , b ³ and c ³ represent mole fractions in the random copolymer, and 0.05 ≦ a ³ ≦ 0.25, respectively. , 0.05 ≦ b ³ ≦ 0.25, 0.50 ≦ c ³ ≦ 0.90 and a ³ + b ³ + c ³ = 1. It is preferable that

  In another aspect of the inorganic clear coating composition of the present invention, (a) the silanol group-containing polyorganosiloxane represented by the general formula (I) is represented by the general formula (V):

（式中、Ｒ^４は、同一または異種の置換もしくは非置換の、合計炭素数が１〜８であるアルキル基を示し、Ｒ^５は同一または異種の置換もしくは非置換の、合計炭素数が６〜８の芳香族基を示し、Ｘは、酸素原子を介して、同一ポリオルガノシロキサン中または他のポリオルガノシロキサン中の骨格に存在するＳｉと結合するシロキサン構造を示し、ａ^４、ｂ^４、ｃ^４、ａ^５およびｃ^５は、ランダムコポリマー中のモル分率を意味し、それぞれ、０．０４≦ａ^４≦０．２４、０．０５≦ｂ^４≦０．２５、０．４０≦ｃ^４≦０．８０、０．０１≦ａ^５≦０．１５、０．０５≦ｃ^５≦０．１５の関係を満たし、さらに０．０５≦ａ^４＋ａ^５≦０．２５およびａ^４＋ｂ^４＋ｃ^４＋ａ^５＋ｃ^５＝１の関係を満たす数である。）で表されるシラノール基含有ポリオルガノシロキサンであることが好ましい。

(In the formula, R ⁴ represents the same or different substituted or unsubstituted alkyl group having 1 to 8 carbon atoms in total, and R ⁵ represents the same or different substituted or unsubstituted alkyl group having 6 carbon atoms in total. -8 represents an aromatic group, and X represents a siloxane structure bonded to Si existing in a skeleton in the same polyorganosiloxane or in another polyorganosiloxane through an oxygen atom, and a ⁴ , b ⁴ , c ⁴ , a ⁵ and c ⁵ mean the mole fraction in the random copolymer, 0.04 ≦ a ⁴ ≦ 0.24, 0.05 ≦ b ⁴ ≦ 0.25, 0.40 ≦ c, respectively. ⁴ ≦ 0.80, 0.01 ≦ a ⁵ ≦ 0.15, 0.05 ≦ c ⁵ ≦ 0.15, and 0.05 ≦ a ⁴ + a ⁵ ≦ 0.25 and a ⁴ + b ⁴ + C ⁴ + a ⁵ + c ⁵ = 1. It is preferable that it is a silanol group containing polyorganosiloxane represented by these.

  In the present invention, a colored pigment-containing coating is formed on an object to be coated to form a colored pigment-containing coating, and the inorganic clear coating is applied on the colored pigment-containing coating to form an inorganic clear coating. A method for forming a multi-layer coating film, wherein the object to be coated is immersed in 1 L of ion-exchanged water having a pH of 6.7 and left to stand at 23 ° C. for 24 hours. This is a method for forming a multilayer coating film, which is a ceramic building material or a slate building material for roofs, having a pH of 8.5 or higher after removing ion exchange water.

  Furthermore, this invention is a multilayer coating film formed by said multilayer coating-film formation method.

  The inorganic clear coating composition of the present invention comprises (a) a silanol group-containing polyorganosiloxane having a specific structure, (b) a silane coupling agent having a specific structure, (c) a curing catalyst, and (d) an inorganic ultraviolet absorber. Because it contains, when it is applied on the building material base material to be coated to form a coating film, the combined action of the alkaline component and ultraviolet rays that elute when the coating object and water come into contact with each other In addition, it is possible to form a coating film that does not easily generate cracks for a long period of time, and that maintains various performances of a high coating film for a long period of time.

  The inorganic clear coating composition of the present invention comprises (a) the general formula (I):

（式中、Ｒ¹は、同一または異種の置換もしくは非置換の、合計炭素数が１〜８である１価の炭化水素基を示し、Ｘは、酸素原子を介して、同一ポリオルガノシロキサン中または他のポリオルガノシロキサン中の骨格に存在するＳｉと結合するシロキサン構造を示し、ａ¹、ｂ¹およびｃ¹は、ランダムコポリマー中のモル分率を意味し、それぞれ、０．０５≦ａ¹≦０．２５、０≦ｂ¹≦０．２５、０．５０≦ｃ¹≦０．９５およびａ¹＋ｂ¹＋ｃ¹＝１の関係を満たす数である。）で表されるシラノール基含有ポリオルガノシロキサン；
（ｂ）一般式（ＩＩ）：

(In the formula, R ¹ represents the same or different substituted or unsubstituted monovalent hydrocarbon group having 1 to 8 carbon atoms in total, and X represents the same polyorganosiloxane through an oxygen atom. Or a siloxane structure bonded to Si present in the skeleton in another polyorganosiloxane, wherein a ¹ , b ¹ and c ¹ mean the mole fraction in the random copolymer, and each represents 0.05 ≦ a ¹ ≦ 0.25, 0 ≦ b ¹ ≦ 0.25, 0.50 ≦ c ¹ ≦ 0.95 and a number satisfying the relationship of a ¹ + b ¹ + c ¹ = 1)) Organosiloxane;
(B) General formula (II):

（式中、Ｙは合計炭素数が１〜８であり、１価の炭化水素基が１つ以上の反応性官能基により置換されたものであり、上記反応性官能基はグリシジルオキシ基、アミノ基、メルカプト基、ビニル基および（メタ）アクリロイル基よりなる群から選択される１種以上の官能基であり、Ｒ^６はフェニル基または全炭素数が１〜８である１価の炭化水素基、Ｒ^７は全炭素数が１〜４のアルキル基、ｎは０〜２の整数を示す。）で表されるシランカップリング剤；
（ｃ）三級アミン化合物およびスズ含有化合物よりなる群から選択される硬化触媒、および、（ｄ）酸化チタン、酸化亜鉛、酸化錫、酸化セリウムからなる群より選ばれる１種以上の化合物である無機紫外線吸収剤を含有する。

(In the formula, Y has 1 to 8 carbon atoms in total, a monovalent hydrocarbon group is substituted with one or more reactive functional groups, and the reactive functional groups are glycidyloxy groups, amino 1 or more functional groups selected from the group consisting of a group, a mercapto group, a vinyl group and a (meth) acryloyl group, and R ⁶ is a phenyl group or a monovalent hydrocarbon group having 1 to 8 carbon atoms in total. , R ⁷ is an alkyl group having 1 to 4 carbon atoms, and n is an integer of 0 to 2).
(C) a curing catalyst selected from the group consisting of a tertiary amine compound and a tin-containing compound, and (d) one or more compounds selected from the group consisting of titanium oxide, zinc oxide, tin oxide and cerium oxide. Contains an inorganic ultraviolet absorber.

The (a) silanol group-containing polyorganosiloxane contained in the inorganic clear coating composition of the present invention has a monomer unit A1 [—Si (R ¹ ) (OH) —O—] as the first monomer unit having a silanol group, Monomer unit B1 [—Si (R ¹ ) ₂ —O—] as the second monomer unit having two hydrocarbon groups and monomer unit C1 [— as the third monomer unit having a siloxane structure bonded to other Si Random copolymer consisting of Si (R ¹ ) (X) —O—], represented by the general formula (I):

で表される。

It is represented by

The molar fraction a ¹ in the copolymer of the monomer unit A1 [—Si (R ¹ ) (OH) —O—] in the general formula (I) is 0.05 to 0.25, preferably 0.10 to 0 .25. If the molar fraction a ¹ is less than 0.05, the content of OH groups serving as the curing point of the random copolymer is too small, and the crosslink density of the coating film becomes low. It becomes easy to become. If it exceeds 0.25, the remaining silanol groups increase, resulting in poor alkali resistance, and even in a long-term weather resistance test, the coating film tends to deteriorate in gloss or crack due to the combined action of an alkali component and ultraviolet rays. Moreover, since the crosslinking of the silanol groups remaining after the coating film formation proceeds, shrinkage cracks after the coating film formation are likely to occur.

The molar fraction b ¹ in the copolymer of the monomer unit B1 [—Si (R ¹ ) ₂ —O—] in the general formula (I) is 0 to 0.25, more preferably 0 to 0.15. is there. When the molar fraction b ¹ exceeds 0.25, the hydrophobic functional groups increase, resulting in a decrease in adhesion, resulting in a decrease in the gloss of the coating film due to the combined action of alkali components and ultraviolet rays in a long-term weather resistance test. And whitening easily occurs.

The molar fraction c ¹ in the copolymer of the monomer unit C1 [—Si (R ¹ ) (X) —O—] in the general formula (I) is 0.50 to 0.95, more preferably 0.60. 0.90. If the molar fraction c ¹ is less than 0.50, problems will be caused by the ratio of other units increases too much. If it exceeds 0.95, the crosslinking density of the coating film becomes high and cracks are likely to occur in the coating film. The molar fractions a ¹ , b ¹ , and c ¹ are ¹ in total.

R ¹ in the general formula (I) represents the same or different substituted or unsubstituted monovalent hydrocarbon group having 1 to 8 carbon atoms in total. The above carbon number includes the carbon atom in the substituent. Examples of the hydrocarbon group include an alkyl group such as a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, a hexyl group, a heptyl group, and an octyl group; a cycloalkyl group such as a cyclopentyl group and a cyclohexyl group; a phenyl group, Aromatic groups such as styryl groups; alkenyl groups such as vinyl groups and allyl groups; halogen-substituted hydrocarbon groups such as chloromethyl groups, γ-chloropropyl groups, and 3,3,3-trifluoropropyl groups; γ-acryloxy Examples thereof include substituted hydrocarbon groups such as a propyl group, a γ-methacryloxypropyl group, a γ-glycidoxypropyl group, and a γ-mercaptopropyl group. Among these, it is preferable that the total number of carbon atoms is 1 to 4 in view of availability, and specifically, the hydrocarbon group is preferably an alkyl group or a phenyl group.

  X in the general formula (I) is bonded to Si existing in the skeleton of the same polyorganosiloxane or in another polyorganosiloxane through an oxygen atom, and a siloxane structure in which the polyorganosiloxane is branched. Show.

The (a) silanol group-containing polyorganosiloxane contained in the inorganic clear coating composition of the present invention is, as one embodiment of the random copolymer represented by the general formula (I), the monomer unit A2 [- A random copolymer of Si (R ² ) (OH) —O—] and the monomer unit C 2 [—Si (R ² ) (X) —O—] as the third monomer unit, represented by the general formula (III):

で表される。

It is represented by

R ² in the general formula (III) represents an identical or different substituted or unsubstituted hydrocarbon group having 1 to 8 carbon atoms in total. Examples of the hydrocarbon group include alkyl groups such as methyl, ethyl, propyl, and butyl; alkenyl groups such as vinyl and allyl; chloromethyl, γ-chloropropyl, 3,3,3-tri Examples include halogen-substituted alkyl groups such as fluoropropyl groups; substituted alkyl groups such as γ-methacryloxypropyl groups, γ-glycidoxypropyl groups, and γ-mercaptopropyl groups. More preferably, they are a methyl group, an ethyl group, and a propyl group.
X in the general formula (III) is the same as X in the general formula (I).

The molar fraction a ² in the copolymer of the monomer unit A2 [—Si (R ² ) (OH) —O—] in the general formula (III) is 0.05 to 0.25, preferably 0.10 to 0 .25. If the molar fraction a ² is less than 0.05, whitening tends to occur in the long-term weather resistance test. When it exceeds 0.25, the alkali resistance is inferior, and in the long-term weather resistance test, coating film gloss is lowered and cracks are likely to occur due to the combined action of an alkali component and ultraviolet rays.

The molar fraction c ² in the copolymer of the monomer unit C2 [—Si (R ² ) (X) —O—] in the general formula (III) is 0.75 to 0.95. When it exceeds 0.95, the crosslinking density of the coating film increases and cracks are likely to occur. The molar fractions a ² and c ² are 1 in total.

The (a) silanol group-containing polyorganosiloxane contained in the inorganic clear coating composition according to the present invention is, as another embodiment of the random copolymer represented by the general formula (I), the monomer unit A3 [ —Si (R ³ ) (OH) —O—], monomer unit B3 [—Si (R ³ ) ₂ —O—] as the _second monomer unit, and monomer unit C3 [—Si (R) as the third monomer unit. ³ ) a random copolymer of (X) -O-], which has the general formula (IV):

で表される。

It is represented by

R ³ in the general formula (IV) may be the same as R ² in the general formula (III).
X in general formula (IV) is the same as X in general formula (I).

  The silanol group-containing polyorganosiloxane represented by the general formula (IV) has a structure in which some of the substituents contain two lower aliphatic hydrocarbon groups, thereby preventing the attack of alkali components on the main chain. The alkali resistance is further improved. Moreover, a softness | flexibility can be provided to a coating film and it becomes difficult to generate | occur | produce a crack.

The molar fraction a ³ in the copolymer of the monomer unit A3 [—Si (R ³ ) (OH) —O—] in the general formula (IV) is 0.05 to 0.25, preferably 0.10 to 0 .25. If the molar fraction a ³ is less than 0.05, remainder water marks on the clear coating film with long-term weathering test, easily whitened. If it exceeds 0.25, the alkali resistance is inferior, and in the long-term weather resistance test, the coating film tends to deteriorate in gloss or crack due to the combined action of the alkali component and ultraviolet rays.

The molar fraction b ³ in the copolymer of the monomer unit B3 [—Si (R ³ ) ₂ —O—] in the general formula (IV) is 0.05 to 0.25, preferably 0.05 to 0.15. It is. When the molar fraction b ³ exceeds 0.25, due to the increased hydrophobic functional group, adhesion is lowered, decrease or whitening of the gloss of the coating film due to the combined action of an alkali component and the ultraviolet long-term weathering test It tends to occur. If it is less than 0.05, the effect which provides the improvement of alkali resistance and the softness | flexibility of a coating film by the said unit is not acquired.

The range of the molar fraction c ³ in the copolymer of the monomer unit C3 [—Si (R ³ ) (X) —O—] in the general formula (IV) is 0.50 to 0.90. The molar fractions a ³ , b ³ and c ³ are 1 in total.

The (a) silanol group-containing polyorganosiloxane contained in the inorganic clear coating composition according to the present invention is, as another embodiment of the random copolymer represented by the general formula (I), the monomer unit A4 [ —Si (R ⁴ ) (OH) —O—] and monomer unit A5 [—Si (R ⁵ ) (OH) —O—], and monomer unit B4 [—Si (R ⁴ ) ₂ — as the second monomer unit. O—] and a random copolymer of monomer unit C4 [—Si (R ⁴ ) (X) —O—] and monomer unit C5 [—Si (R ⁵ ) (X) —O—] as the third monomer unit General formula (V):

で表される。

It is represented by

R ⁴ in the general formula (V) may be the same as R ³ in the general formula (IV). R ⁵ in the general formula (V) represents the same or different substituted or unsubstituted aromatic group having 6 to 8 carbon atoms in total. Examples of the aromatic group include a phenyl group and a styryl group. Among these, a phenyl group is preferable from the viewpoint of availability.
X in the general formula (V) is the same as X in the general formula (I).

  Since the structure of the silanol group-containing polyorganosiloxane represented by the general formula (V) includes an aromatic ring having a large steric hindrance in some substituents, the alkali resistance and chemical resistance of the clear coating film are improved.

The molar fraction a ⁴ in the copolymer of the monomer unit A4 [—Si (R ⁴ ) (OH) —O—] in the general formula (V) is 0.04 to 0.24, preferably 0.10 to 0 .24.

The molar fraction a ⁵ in the copolymer of the monomer unit A5 [—Si (R ⁵ ) (OH) —O—] in the general formula (V) is 0.01 to 0.15, preferably 0.01 to 0. .10. When the molar fraction a ⁵ exceeds 0.15, the reactivity of the Si-OH is whitening tends to occur with long-term weathering test the crosslinking density of lower coating film decreases. The molar fractions a ⁴ and a ⁵ are preferably in the range of 0.05 to 0.25 in total.

The molar fraction b ⁴ in the copolymer of the monomer unit B4 [—Si (R ⁴ ) ₂ —O—] in the general formula (V) is 0.05 to 0.25, preferably 0.10 to 0.25. It is. When the molar fraction b ⁴ exceeds 0.25, the adhesion is lowered, the gloss of the coating film with long-term weathering test may be reduced. If it is less than 0.05, the effect including the unit cannot be obtained.

The molar fraction c ⁴ in the copolymer of the monomer unit C4 [—Si (R ⁴ ) (X) —O—] in the general formula (V) is 0.40 to 0.80.

The molar fraction c ⁵ in the copolymer of the monomer unit C5 [—Si (R ⁵ ) (X) —O—] in the general formula (V) is 0.05 to 0.15, preferably 0.05 to 0. .10. When the molar fraction c ⁵ exceeds 0.15, the crosslinking density of the coating film whitening tends to occur with long-term weathering test decreases. The molar fractions a ⁴ , a ⁵ , b ⁴ , c ⁴ and c ⁵ are 1 in total.

The molar fraction can be determined by, for example, ²⁹ Si-NMR spectrum. Specifically, for example, in the case of a silanol group-containing polyorganosiloxane represented by the general formula (V), the first monomer unit A4 [—Si (R ⁴ ) (OH) —O—] is used. The Si signal can be observed in the vicinity of −53 to −60 ppm, and the Si signal of the monomer unit A5 [—Si (R ⁵ ) (OH) —O—] can be observed in the vicinity of −67 to −73 ppm. The integrated values of these signals are T2 and T2 ′. Further, the Si signal of the monomer unit B4 [—Si (R ⁴ ) ₂ —O—] as the _second monomer unit can be observed in the vicinity of −15 to −25 ppm. The integrated value of this signal is D2. The monomer unit C4 [—Si (R ⁴ ) (X) —O—] of the third monomer unit has a Si signal in the vicinity of −62 to −70 ppm, and the monomer unit C5 [—Si (R ⁵ ) (X) — The O-] Si signal can be observed in the vicinity of -74 to -84 ppm. The integrated values of these signals are T3 and T3 ′.
The peak of the monomer unit A5 is observed on the higher magnetic field side than the C4 NMR peak.

Calculation of mole fraction, for example, if the mole fraction a ^4, can be calculated by the following expression. Other mole fractions can be calculated in a similar manner.

[Equation 1]
Molar fraction a ⁴ = T2 / (T2 + T2 ′ + D2 + T3 + T3 ′)

  (A) The silanol group-containing polyorganosiloxane is a monovalent having 1 to 8 carbon atoms in total, having the same or different substituted or unsubstituted methyltrichlorosilane, ethyltrichlorosilane, phenyltrichlorosilane, dimethyldichlorosilane, etc. Obtained by hydrolyzing an alkyltrichlorosilane having a hydrocarbon group, aromatic trichlorosilane or dialkyldicyclosilane, or one or a mixture of two or more alkoxysilanes corresponding thereto with a large amount of water by a known method. Can do.

Silanol groups cause a condensation reaction between silanol groups or between a silanol group and an alkoxysilyl group, but the condensation reaction rate varies depending on conditions such as reaction temperature, reaction time, and concentration during the reaction. The reaction conditions are appropriately adjusted by calculating the molar fraction of the first monomer unit having a silanol group by the above measurement method based on ²⁹ Si-NMR spectrum during the reaction.

  (A) The weight average molecular weight of the silanol group-containing polyorganosiloxane is 1,500 to 200,000, preferably 3,000 to 100,000, in terms of polystyrene as measured by gel permeation chromatography (GPC).

  If the weight average molecular weight is less than 1,500, the coating film is not sufficiently formed, and the alkali resistance and chemical resistance may be lowered. If it exceeds 200,000, the stability of the paint may be reduced.

  Content of (a) silanol group containing polyorganosiloxane in 100 mass parts of solid content of the inorganic clear coating composition of this invention is 2-40 mass parts. If it is less than 2 parts by mass, the coating efficiency is poor, and if it exceeds 40 parts by mass, the viscosity is too high and the coating production efficiency and the coating workability may be inferior.

  The (b) silane coupling agent contained in the inorganic clear coating composition of the present invention has the following general formula (II):

で表される構造を有するものである。

It has the structure represented by these.

  Y in the (b) silane coupling agent contained in the inorganic clear coating composition according to the present invention is a monovalent hydrocarbon group substituted with one or more reactive functional groups and having 1 to 8 carbon atoms in total. The reactive functional group is at least one functional group selected from the group consisting of a glycidyloxy group, an amino group, a mercapto group, a vinyl group, and a (meth) acryloyl group.

  The (b) silane coupling agent contained in the inorganic clear coating composition according to the present invention is (a) crosslinked with the silanol group of the silanol group-containing polyorganosiloxane to reduce the residual silanol, thereby reducing the alkali resistance of the coating film. To improve. Moreover, a softness | flexibility can be provided to a coating film and generation | occurrence | production of the crack in a long-term weather resistance test can be prevented.

(B) R ⁶ in the silane coupling agent is a phenyl group or a hydrocarbon group having 1 to 8 carbon atoms, and more preferably a phenyl group, a methyl group, an ethyl group, a propyl group, or a butyl group. R ⁷ is an alkyl group having 1 to 4 carbon atoms, more preferably a methyl group or an ethyl group.

  In the (b) silane coupling agent contained in the inorganic clear coating composition according to the present invention, the silane coupling agent that can be used is not particularly limited. For example, Shin-Etsu Chemical Co., Ltd., Momentive Performance Materials, Vinyltrimethoxysilane, vinyltriethoxysilane, γ-aminopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, γ-methacryloxypropylmethyl sold by Toray Dow Corning, Evonik Degussa Japan, Chisso, etc. Dimethoxysilane, γ-acryloxypropyltrimethoxysilane, γ-methacryloxypropyltrimethoxysilane, γ-glycidoxypropyltriethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, γ-glycidoxypropylto Limethoxysilane, γ-glycidoxypropylmethyldimethoxysilane, N-β (aminoethyl) γ-aminopropyltrimethoxysilane, N-β- (aminoethyl) -γ-aminopropylmethyldimethoxysilane, γ-mercaptopropyl A trimethoxysilane etc. can be mentioned. These silane coupling agents may be used alone or in combination of two or more. Among these, it is more preferable to use a silane coupling agent having a glycidyloxy group because it has a particularly excellent effect in improving adhesion.

  In the inorganic clear coating composition of the present invention, the solid content mass ratio of (a) silanol group-containing polyorganosiloxane and (b) silane coupling agent is preferably 90:10 to 60:40. (B) If the ratio of the silane coupling agent is less than 10, crosslinking of the coating does not proceed sufficiently, the remaining silanol groups increase, the coating is not flexible, and gloss is obtained in a long-term weather resistance test. May decrease. (B) When the ratio of the silane coupling agent exceeds 40, the crosslinking proceeds too much, stress is applied to the coating film, and cracks may occur. More preferably, it is 85: 15-65: 35.

  The (c) curing catalyst contained in the inorganic clear coating composition of the present invention is selected from the group consisting of tertiary amine compounds and tin-containing compounds. Specific examples of the tertiary amine compound include trimethylamine, triethylamine, tributylamine, amines such as N, N-dimethyldodecylamine; ethanolamines such as triethanolamine; N, N-dimethylethanolamine, N, Amino alcohols such as N-diethylethanolamine and N-methyldiethanolamine; other organic compounds having an amino group such as pyridine, polyvinylamine and polyallylamine; 1,8-diazabicyclo [5.4.0] undecene-7 (DBU), 1,4-diazabicyclo [2.2.2] octane (DABCO), 1,5-diazabicyclo [4.3.0] nonene-5 (DBN) and the like.

  Specific examples of the tin-containing compound include dibutyltin dilaurate, dibutyltin dioctate, dibutyltin diacetate, dibutyltin dioleate, dioctyltin dilaurate, diphenyltin diacetate, dibutyltin oxide, dibutyltin dimethoxide, and dibutyltin (triethoxysiloxy) tin. And dibutyltin bis (acetylacetonate).

  The (c) curing catalyst is preferably selected from the group consisting of DBU, N, N-dimethyldodecylamine, dibutyltin dilaurate, dioctyltin dilaurate, and dibutyltin diacetate, and only one type may be used. You may use combining more than a seed.

  In the inorganic clear coating composition of the present invention, the content of the (c) curing catalyst is preferably 0.1 to 10% by mass with respect to the solid content mass of the (a) silanol group-containing polyorganosiloxane.

  The inorganic ultraviolet absorber (d) contained in the inorganic clear coating composition according to the present invention is one or more compounds selected from the group consisting of titanium oxide, zinc oxide, tin oxide and cerium oxide. By using an inorganic ultraviolet absorber, long-term weather resistance of the resulting coating film can be maintained, and alkali resistance can also be improved. Zinc oxide or cerium oxide is more preferred, and those surfaces subjected to hydrophobic treatment are more preferred. As such a commercial product, for example, in the case of zinc oxide, a high-density coating layer made of a hydrous silicon acid compound is formed on the surface of the zinc oxide fine particles, such as NANOFINE-50A (manufactured by Sakai Chemical Industry Co., Ltd.). Furthermore, the thing which formed the coating layer with organopolysiloxane on it further is mentioned.

  The average particle size of the inorganic ultraviolet absorber is preferably 0.20 μm or less, more preferably 0.15 μm or less. When the average particle diameter exceeds 0.20 μm, the coating film becomes cloudy. The said average particle diameter is volume conversion and can be determined by measuring with a laser light scattering method.

In the inorganic clear coating composition of the present invention, the mass ratio of the total solid content of (a) silanol group-containing polyorganosiloxane and (b) silane coupling agent to the solid content of (d) inorganic ultraviolet absorber is 100: 10. It is preferably ~ 100: 50. (D) If the ratio of the inorganic ultraviolet absorber is less than 10, the weather resistance of the coating film obtained when the amount of the inorganic ultraviolet absorber is too small may be lowered. (D) When the ratio of the inorganic ultraviolet absorber exceeds 50, there is a possibility that cracks may occur in the coating film obtained because the amount of the inorganic ultraviolet absorber is too large.
The inorganic ultraviolet absorber may be added directly to the inorganic clear coating composition, or may be added after making a paste with a dispersion resin and a solvent.

  In addition to the silanol group-containing polyorganosiloxane, (b) silane coupling agent, (c) curing catalyst, and (d) inorganic ultraviolet absorber, the inorganic clear coating composition of the present invention is the same as the ordinary coating material. Various additives and the like can be included. Examples of the various additives include surface conditioners, antiseptics, fungicides, antifoaming agents, light stabilizers, antioxidants, viscosity modifiers, and the like. The inorganic clear coating composition of the present invention can be prepared by mixing and stirring the above-described components with a stirrer or the like.

  In the method for forming a multilayer coating film of the present invention, a colored pigment-containing coating is formed on an object to be coated to form a colored pigment-containing coating, and the above-described inorganic clear coating composition is applied thereon to form an inorganic coating. A clear coating film is formed.

  The coating object is obtained by immersing 100 g of the coating object in 1 L of ion-exchanged water having a pH of 6.7 and allowing it to stand at 23 ° C. for 24 hours, so that the pH of the ion-exchanged water after removing the coating object is It is a ceramic building material or roof slate building material that is 8.5 or more. In such an object to be coated, an alkaline component is eluted by contact with water, and the multilayer coating film forming method of the present invention can exhibit an excellent effect. The ceramic building material or the slate building material for roof is specifically used as an outer wall finishing material, and the ceramic building material is also called a ceramic siding. The ceramic building material and the slate building material for roof are specifically manufactured by molding into a plate shape using cement, siliceous raw material, fibrous raw material, admixture, etc., and drying (curing / curing). , Building materials specified in JIS A 5422, decorative slate specified in JIS A 5423, hard wood cement board, extruded cement board, lightweight foamed concrete (ALC), and the like. The pH of ion-exchanged water according to the above test is, for example, 11.4 for hard wood cement board, 11.2 for extruded cement board, and 9.8 for lightweight foamed concrete (ALC). In addition, it is 6.7 in an aluminum plate, and there is no change.

  In order to improve adhesion, water resistance, water permeation resistance, and the like, the object to be coated may be previously applied with a sealer usually used by those skilled in the art to form a sealer coating film.

Multi-layer coating film forming method In the multi-layer coating film forming method of the present invention, first, a color pigment-containing coating film is formed by applying a color pigment-containing paint on the article to be coated.
The colored pigment-containing paint usually contains a resin and a colored pigment. It does not specifically limit as said resin, An acrylic resin, an acrylic urethane resin, a fluororesin, a polyester resin, an epoxy resin, a urethane resin emulsion, a vinyl acetate resin emulsion, a fluororesin emulsion, a vinyl chloride emulsion etc. can be mentioned.

  The color pigment is not particularly limited, and examples thereof include organic color pigments such as diketopyrrolopyrrole pigments, phthalocyanine pigments, quinacridone pigments, and isoindolinone pigments; yellow iron oxide, bengara, titanium yellow, Examples thereof include inorganic colored pigments such as zinc white, carbon black, titanium dioxide, and cobalt blue; mica pigments; alumina flake pigments, metallic titanium flakes, and colored flat pigments.

  The color pigment-containing paint may contain other components as necessary in addition to the resin and the color pigment. Other components include, for example, extender pigments (calcium carbonate, barium sulfate, barium carbonate, magnesium silicate, clay, talc, silica, calcined kaolin, etc.) design materials (sand, cinnabar sand, colored sand, beads, colored chips, glass chips and Color beads, etc.), film-forming aids, surface conditioners, antiseptics, fungicides, antifoaming agents, light stabilizers, antioxidants, pH adjusters, viscosity adjusters and the like.

  The pigment mass concentration (PWC) with respect to the solid content of the colored pigment-containing coating is preferably 5 to 70% by mass. When the PWC is less than 5% by mass, the base concealing property is inferior, and when the PWC exceeds 70% by mass, the weather resistance may be lowered. The PWC is more preferably 20 to 45% by mass.

  The colored pigment-containing paint can be prepared by stirring and mixing the resin, the colored pigment, and if necessary, other components with a stirrer or the like.

  The application method of the color pigment-containing paint is not particularly limited, and for example, commonly used applications such as immersion, brush, roller, roll coater, air spray, airless spray, curtain flow coater, roller curtain coater, die coater, etc. The method etc. can be mentioned. These can be appropriately selected according to the use of the substrate.

After coating, the colored pigment-containing coating film can be formed by leaving or heating as it is and forced drying.
The color pigment-containing coating film thus obtained has a thickness of 5 to 350 μm, preferably 20 to 300 μm.

  In the method for forming a multilayer coating film of the present invention, the inorganic clear coating film is then formed by applying the above-mentioned inorganic clear coating material on the obtained color pigment-containing coating film. The method for applying the inorganic clear paint is not particularly limited, and examples thereof include those described for the color pigment-containing paint.

After coating, the inorganic clear coating film can be formed by leaving or heating as it is and forced drying.
The film thickness of the inorganic clear coating film thus obtained is 0.5 to 10 μm, preferably 1 to 5 μm.

  In addition, the hydrophilic treatment film | membrane can be formed by apply | coating a hydrophilic treatment agent on the obtained inorganic clear coating film after the multilayer coating-film formation method of this invention. The hydrophilic treatment agent is not particularly limited, and examples thereof include those comprising a surfactant and colloidal silica and further containing a photocatalyst such as zinc oxide and titanium oxide. It does not specifically limit as a coating method of the said hydrophilic treatment agent, What was described by the said color pigment containing coating material is mentioned.

Multi-layer coating film The multi-layer coating film of the present invention is obtained by the above-mentioned multi-layer coating film forming method. The film thickness of the multilayer coating film of the present invention is 6 to 350 μm, preferably 20 to 300 μm.

Production Example 1 Preparation of Silanol Group-Containing Polyorganosiloxane 1 As shown in Table 1, 300 parts of methyltrichlorosilane was mixed with 300 parts of toluene, and 700 parts of water and 100 parts of methanol in a container equipped with a reflux condenser. The mixture was added dropwise with stirring while keeping the temperature at 50 ° C. or lower, and hydrolyzed / condensed over 8 hours. The produced silanol group-containing polyorganosiloxane was washed with water to remove by-produced hydrogen chloride. This was heated under reduced pressure to remove water remaining as a part of the solvent, and a toluene solution A of a silanol group-containing polyorganosiloxane having a solid content concentration of 50% was obtained. The obtained toluene solution A was charged into a solvent removal apparatus equipped with a stirrer, a condenser, a decompression device, and a thermometer, heated to 50 ° C. under reduced pressure, and the solvent was completely distilled off over 5 hours. The resulting silanol group-containing polyorganosiloxane 1 was a solid having a softening point of 109 ° C.

Monomer unit A2 [—Si (CH ₃ ) (OH) —O—] as the first monomer unit and monomer unit C2 [— as the third monomer unit contained in the obtained silanol group-containing polyorganosiloxane 1 Si (CH ₃ ) (X) —O—] was determined by ²⁹ Si-NMR spectrum. X represents a siloxane structure bonded to Si existing in a skeleton in the same polyorganosiloxane or another polyorganosiloxane through an oxygen atom.
Specifically, since the Si signal of the monomer unit A2 can be observed in the vicinity of −53 to −60 ppm and the Si signal of the monomer unit C2 can be observed in the vicinity of −62 to −70 ppm, the integral value of these signals is obtained.
Then, an integral value of Si signal monomer units A2 T2, when the integral value of the Si signal monomer units C2 and T3, the molar fraction a ² monomer units A2 can be calculated by the following expression.

[Equation 1]
Molar fraction a ² = T2 / (T2 + T3)

Since the silanol group-containing polyorganosiloxane 1 had D2 = 0, T2 = 1.2716, and T3 = 7.1618, the molar fraction a ² determined by ²⁹ Si-NMR spectrum was 1.2716 / (1 2716 + 7.1618) = 0.15. The molar fraction ^{c 2} was 0.85.

  It was 9,600 when the weight average molecular weight of the obtained silanol group containing polyorganosiloxane 1 was measured by gel permeation chromatography, and converted into polystyrene.

Production Example 2 Preparation of Silanol Group-Containing Polyorganosiloxane 2 Similarly to Production Example 1, a liquid silanol group-containing polyorganosiloxane 2 was prepared based on the formulation shown in Table 1.
Monomer unit A3 [—Si (CH ₃ ) (OH) —O—], monomer unit B3 [—Si (CH ₃ ) ₂ —O—], monomer unit C3 [— of the resulting silanol group-containing polyorganosiloxane 2 The molar fractions a ³ , b ³ , and c ³ of Si (CH ₃ ) (X) —O—] were determined by ²⁹ Si-NMR spectrum. The Si signals of monomer units A3 and C3 are observed at the same positions as monomer units A2 and C2. The Si signal of monomer unit B3 can be observed in the vicinity of −15 to −25 ppm. The integrated value of the observed peak was determined and the molar fraction was calculated. The obtained molar fraction is shown in Table 1.
Moreover, the weight average molecular weight by polystyrene conversion was 55,000.

Production Example 3 Preparation of Silanol Group-Containing Polyorganosiloxane 3 Similarly to Production Example 1, a liquid silanol group-containing polyorganosiloxane 3 was prepared based on the formulation shown in Table 1.
Monomer unit A4 [—Si (CH ₃ ) (OH) —O—], monomer unit A5 [—Si (Ph) (OH) —O—], monomer unit B4 [] of the resulting silanol group-containing polyorganosiloxane 3 _{-Si (CH 3) 2 -O-]} , the monomer unit _{C4 [-Si (CH 3) (} X) -O-], the molar fraction of the monomer unit C5 [-Si (Ph) (X ) -O-] a ⁴ , a ⁵ , b ⁴ , c ⁴ , and c ⁵ were determined by ²⁹ Si-NMR spectrum. The Si signals of monomer units A4, B4 and C4 are observed at the same positions as monomer units A3, B3 and C3. The Si signal of the monomer unit B5 can be observed near -67 to -73 ppm, and the Si signal of the monomer unit B5 can be observed near -74 to -84 ppm. The integrated value of the observed peak was determined and the molar fraction was calculated. The obtained molar fraction is shown in Table 1.
Moreover, the weight average molecular weight by polystyrene conversion was 23,000.

Production Example 4 Preparation of Silanol Group-Containing Polyorganosiloxane 4 Similarly to Production Example 1, a liquid silanol group-containing polyorganosiloxane 4 was prepared based on the formulation shown in Table 1.
Monomer unit A3 [—Si (CH ₃ ) (OH) —O—], monomer unit B3 [—Si (CH ₃ ) ₂ —O—], monomer unit C3 [— of the resulting silanol group-containing polyorganosiloxane 4 The molar fractions a ³ , b ³ , and c ³ of Si (CH ₃ ) (X) —O—] were determined by ²⁹ Si-NMR spectrum. The Si signals of monomer units A3 and C3 are observed at the same positions as monomer units A2 and C2. The Si signal of monomer unit B3 can be observed in the vicinity of −15 to −25 ppm. The integrated value of the observed peak was determined and the molar fraction was calculated. The obtained molar fraction is shown in Table 1.
Moreover, the weight average molecular weight by polystyrene conversion was 135,000.

Production Example 5 Preparation of Silanol Group-Containing Polyorganosiloxane 5 Similarly to Production Example 1, a liquid silanol group-containing polyorganosiloxane 5 was prepared based on the formulation shown in Table 1.
In the same manner as in Production Example 2, the molar fraction was determined by ²⁹ Si-NMR spectrum. The obtained molar fraction is shown in Table 1.
The weight average molecular weight in terms of polystyrene was 14,300.

Production Example 6 Preparation of Silanol Group-Containing Polyorganosiloxane 6 Similar to Production Example 1, after preparing a silanol group-containing polyorganosiloxane solution based on the formulation shown in Table 1, the resulting solution was stirred with a stirrer, condenser, and decompressor. The solvent was completely distilled off for 8 hours at room temperature under reduced pressure. The resulting silanol group-containing polyorganosiloxane 6 was liquid at room temperature.
The molar fraction was determined by ²⁹ Si-NMR spectrum in the same manner as in Production Example 3. The obtained molar fraction is shown in Table 1.
The weight average molecular weight in terms of polystyrene was 5,400.

Production Example 7 Preparation of Silanol Group-Containing Polyorganosiloxane 7 Similarly to Production Example 1, a silanol group-containing polyorganosiloxane solution was prepared based on the formulation shown in Table 1, and then the resulting solution was stirred. , And a desolventizer equipped with a thermometer, heated to 50 ° C. under reduced pressure, and the solvent was completely distilled off over 5 hours. Thereafter, the heating time was extended for 12 hours to reduce the amount of silanol groups. The resulting silanol group-containing polyorganosiloxane 7 was a liquid.
In the same manner as in Production Example 2, the molar fraction was determined by ²⁹ Si-NMR spectrum. The obtained molar fraction is shown in Table 1.
The weight average molecular weight in terms of polystyrene was 30,000.

Production Example 8 Preparation of Fine Zinc Oxide Paste NANOFINE-50A (trade name, fine particle zinc oxide having an average particle size of 0.025 μm, manufactured by Sakai Chemical Co., Ltd.) 40 parts, DISPERBYK-110 (trade name, wetting dispersant, Big Chemie 5 parts of Japan) and 55 parts of methoxypropyl acetate as a diluent solvent were added and stirred with a disper for about 30 minutes. Furthermore, using a 1 mm glass bead, a fine particle zinc oxide paste was prepared by dispersing for 1 hour at 3,000 rpm using a sand mill.

Production Example 9 Preparation of Colored Pigment-Containing Paint DISPERBYK-190 (trade name, wetting and dispersing agent, manufactured by Big Chemie Japan) 3 parts, titanium CR-95 (trade name, titanium dioxide, manufactured by Ishihara Sangyo Co., Ltd.), sedimentation Ricabond ES-85 (trade name, solid content) as an anionic aqueous resin dispersion in titanium white dispersion paste comprising 40 parts of barium sulfate # 100 (trade name, precipitated barium sulfate, manufactured by Sakai Chemical Co., Ltd.) and 20 parts of deionized water 208 parts of acrylic resin with a concentration of 51.0% (manufactured by Chuo Rika Kogyo Co., Ltd.) and 0.5 parts of 25% aqueous ammonia are mixed, and Sanol LS292 (trade name, hindered amine light stabilizer, Sankyo Co., Ltd.) 1 part, 11 parts of texanol (trade name, film-forming aid, manufactured by Eastman) and 240 parts of deionized water were added. Finally, the viscosity is adjusted by adding a thickener (trade name: Primal ASE-60, manufactured by Rohm & Haas) so that it takes 40 seconds with NK-2 cup (trade name, viscosity cup, manufactured by Anest Iwata). Thus, a colored pigment-containing paint was obtained.

Example 1
As shown in Table 2, 80 parts of the silanol group-containing polyorganosiloxane 1 obtained in Production Example 1 was dissolved in 80 parts of toluene. Thereafter, 20 parts of 3-glycidoxypropyltrimethoxysilane as a silane coupling agent and 1 part of Enabilizer L-101 (trade name, dibutyltin dilaurate, manufactured by Tokyo Fine Chemical Co., Ltd.) as a curing catalyst were obtained in Production Example 8. 40 parts of fine particle zinc oxide paste and 400 parts of toluene were added and mixed by stirring to obtain an inorganic clear coating composition 1.

A hard wood cement board, which is a ceramic building material, was prepared. In addition, 100 g of the object to be coated is immersed in 1 L of ion-exchanged water having a pH of 6.7, and is left to stand at 23 ° C. for 24 hours. After removing the object to be coated, the pH of the ion-exchanged water is 11.4. Met.
On the object to be coated, an odeite 128 sealer (trade name, sealer, manufactured by Nippon Paint Co., Ltd.) was applied by air spray so as to have a dry film thickness of 50 μm, and dried at room temperature for 4 hours. Next, the color pigment-containing paint obtained in Production Example 9 was applied onto the sealer by air spray so that the dry film thickness was 50 μm, and heated at 80 ° C. for 10 minutes to form a color pigment-containing coating film.
Further, the inorganic clear coating composition 1 prepared as described above was applied onto the obtained colored pigment-containing coating film by air spray so as to have a dry film thickness of 5 μm, and heated at 120 ° C. for 10 minutes to form an inorganic clear coating film. Thus, a multilayer coating film having a dry film thickness of 55 μm was obtained.

  The resulting multilayer coating film was evaluated for alkali resistance, freeze-thaw resistance, and accelerated weather resistance according to the following criteria. The evaluation results are shown in Table 3.

[Evaluation criteria]
A. Alkali Resistance The coated object having the obtained multilayer coating film was immersed in a saturated calcium hydroxide solution, and the appearance of the coating film after 10 days was visually evaluated. A score of 4 or more was accepted. The evaluation criteria were as follows.
5 No abnormality at all.
4 Partially reduced gloss.
3 The gloss decreased on the entire surface.
2 Partial whitening and cracking occurred.
1 Whitening and cracks occurred on the entire surface.

B. Freezing and thawing resistance The coated object having the obtained multilayer coating film was subjected to a frost damage resistance test (a method for thawing in the air in frozen water) as specified in JIS A 1435, and the coating film appearance after 200 cycles was visually evaluated. . A score of 4 or more was accepted. The evaluation criteria were as follows.
5 No cracks have occurred.
4 Cracks are generated, and the area is less than 5% of the entire coating film. 3 Cracks are generated, and the area is 5% or more and less than 30% of the entire coating film.
2 Cracks occur, and the area is 30% or more and less than 50% of the entire coating film.
1 Cracks occur, and the area is 50% or more of the entire coating film.

C. Accelerated weather resistance The object to be coated having the obtained multilayer coating film is irradiated with an I-super UV tester manufactured by Iwasaki Electric Co., Ltd. for 6 hours of irradiation (temperature 63 ° C, humidity 40%), 2 hours wet (humidity 95%) for 1 cycle. Then, an accelerated weather resistance test was conducted, and the gloss retention was evaluated with a digital variable angle gloss meter (manufactured by Suga Test Instruments Co., Ltd.) for the appearance of the coating film after 100 cycles. A score of 4 or more was accepted. The evaluation criteria were as follows.
5 Gloss retention is 90% or more.
4 Gloss retention is 70% or more and less than 90%.
3 Gloss retention is 50% or more and less than 70%.
2 Gloss retention is 20% or more and less than 50%.
1 Gloss retention is less than 20%.

Examples 2-4
According to the formulation in Table 2, inorganic clear coating compositions 2 to 4 were obtained in the same manner as in Example 1.
Furthermore, it replaced with the inorganic clear coating composition 1, and obtained the multilayer coating film like Example 1 except having used the obtained inorganic clear coating compositions 2-4, respectively.
About the to-be-coated object which has the obtained multilayer coating film, it carried out similarly to Example 1, and evaluated alkali resistance, freeze-thaw resistance, and accelerated weather resistance. The evaluation results are shown in Table 3.

Example 5
According to the formulation in Table 2, an inorganic clear coating composition 5 was obtained in the same manner as in Example 1.
Further, Example 1 was used except that an extruded cement board, which was a ceramic building material, was used as an object to be coated, and that the obtained inorganic clear coating composition 5 was used in place of the inorganic clear coating composition 1. Similarly, a multilayer coating film was obtained.

About the to-be-coated object which has the obtained multilayer coating film, it carried out similarly to Example 1, and evaluated alkali resistance, freeze-thaw resistance, and accelerated weather resistance. The evaluation results are shown in Table 3.
In addition, 100 g of the object to be coated is immersed in 1 L of ion-exchanged water having a pH of 6.7, and is left to stand at 23 ° C. for 24 hours. After removing the object to be coated, the pH of the ion-exchanged water is 11.2. Met.

Example 6
According to the formulation in Table 2, an inorganic clear coating composition 6 was obtained in the same manner as in Example 1.
Further, Example 1 except that a lightweight foamed cement board, which is a ceramic building material, was used as an object to be coated, and that the obtained inorganic clear coating composition 6 was used instead of the inorganic clear coating composition 1. Similarly, a multilayer coating film was obtained.

About the to-be-coated object which has the obtained multilayer coating film, it carried out similarly to Example 1, and evaluated alkali resistance, freeze-thaw resistance, and accelerated weather resistance. The evaluation results are shown in Table 3.
In addition, 100 g of the object to be coated is immersed in 1 L of ion-exchanged water having a pH of 6.7, left to stand at 23 ° C. for 24 hours, and the pH of the ion-exchanged water after removing the object to be coated is 9.8. Met.

Comparative Examples 1-5
According to the formulation in Table 2, inorganic clear coating compositions 7 to 11 were obtained in the same manner as in Example 1.
Furthermore, it replaced with the inorganic clear coating composition 1, and obtained the multilayer coating film like Example 1 except having used each of the obtained inorganic clear coating compositions 7-11.
About the to-be-coated object which has the obtained multilayer coating film, it carried out similarly to Example 1, and evaluated alkali resistance, freeze-thaw resistance, and accelerated weather resistance. The evaluation results are shown in Table 3.

Reference example 1
A multilayer coating film was obtained in the same manner as in Example 1 except that an aluminum plate was used as the article to be coated.
About the to-be-coated object which has the obtained multilayer coating film, it carried out similarly to Example 1, and evaluated alkali resistance, freeze-thaw resistance, and accelerated weather resistance. The evaluation results are shown in Table 3.
In addition, 100 g of the object to be coated is immersed in 1 L of ion-exchanged water having a pH of 6.7, and left to stand at 23 ° C. for 24 hours, and the pH of the ion-exchanged water after removing the object to be coated is 6.7. Met.

As can be seen from the evaluation results shown in Table 3, an inorganic clear coating composition containing silanol group-containing polyorganosiloxanes 1 to 4 having (CH ₃ ) ₂ Si groups or Si—OH groups in an amount specified in the present invention. The evaluation result of the multilayer coating film obtained using 1-6 was a pass also about any evaluation item.

However, the silanol group-containing polyorganosiloxane 5 having too many hydrophobic (CH ₃ ) ₂ Si groups, the silanol group-containing polyorganosiloxane 6 having too many Si—OH groups, and the silanol group-containing polyorganosiloxane 7 having too few SiOH groups. The evaluation results of the multilayer coating films obtained using the inorganic clear coating compositions 7 to 9 containing each of the above were rejected for at least one evaluation item.

  In addition, the evaluation results of the multilayer coating film obtained using the inorganic clear coating composition 10 containing no silane coupling agent and the inorganic clear coating composition 11 containing no inorganic ultraviolet absorber are also at least one or more. The evaluation item was rejected.

  The inorganic clear coating composition of the present invention can be suitably used for ceramic building materials or slate building materials for roofs.

Claims (7)

(A) General formula (I):

(In the formula, R ¹ represents the same or different substituted or unsubstituted monovalent hydrocarbon group having 1 to 8 carbon atoms in total, and X represents the same polyorganosiloxane through an oxygen atom. Or a siloxane structure bonded to Si present in the skeleton in another polyorganosiloxane, wherein a ¹ , b ¹ and c ¹ mean the mole fraction in the random copolymer, and each represents 0.05 ≦ a ¹ ≦ 0.25, 0 ≦ b ¹ ≦ 0.25, 0.50 ≦ c ¹ ≦ 0.95 and a number satisfying the relationship of a ¹ + b ¹ + c ¹ = 1.) Organosiloxane;
(B) General formula (II):

(In the formula, Y has 1 to 8 carbon atoms in total, and a monovalent hydrocarbon group is substituted with one or more reactive functional groups, and the reactive functional groups are glycidyloxy groups, amino 1 or more functional groups selected from the group consisting of a group, a mercapto group, a vinyl group and a (meth) acryloyl group, and R ⁶ is a phenyl group or a monovalent hydrocarbon group having 1 to 8 carbon atoms in total. , R ⁷ is an alkyl group having 1 to 4 carbon atoms, and n is an integer of 0 to 2).
(C) a curing catalyst selected from the group consisting of tertiary amine compounds and tin-containing compounds; and (d) one or more compounds selected from the group consisting of titanium oxide, zinc oxide, tin oxide and cerium oxide. An inorganic clear coating composition containing an ultraviolet absorber.   (A) The solid content mass ratio of the silanol group-containing polyorganosiloxane represented by the general formula (I) and the silane coupling agent represented by (b) the general formula (II) is (a) :( b) The inorganic clear coating composition according to claim 1, wherein = 90: 10 to 60:40. (A) The silanol group-containing polyorganosiloxane represented by the general formula (I) is represented by the general formula (III):

(In the formula, R ² represents the same or different substituted or unsubstituted alkyl group having 1 to 8 carbon atoms in total, and X represents an oxygen atom through the same polyorganosiloxane or other polyalkylene. shows a siloxane structure binds to Si present in the backbone of the organosiloxane, ^{a 2} and ^{c 2} means a molar fraction in the random copolymer, respectively, 0.05 ≦ ^{a 2} ≦ 0.25,0. The inorganic clear coating composition according to claim 1, which is a silanol group-containing polyorganosiloxane represented by the following formula: 75 ≦ c ² ≦ 0.95 and a ² + c ² = 1. (A) The silanol group-containing polyorganosiloxane represented by the general formula (I) is represented by the general formula (IV):

(In the formula, R ³ represents the same or different substituted or unsubstituted alkyl group having 1 to 8 carbon atoms in total, and X represents an oxygen atom through the same polyorganosiloxane or other polyalkylene. A siloxane structure bonded to Si present in the skeleton in the organosiloxane is shown, and a ³ , b ³ and c ³ represent mole fractions in the random copolymer, and 0.05 ≦ a ³ ≦ 0.25, respectively. , 0.05 ≦ b ³ ≦ 0.25, 0.50 ≦ c ³ ≦ 0.90 and a ³ + b ³ + c ³ = 1. The inorganic clear coating composition according to claim 1, wherein (A) The silanol group-containing polyorganosiloxane represented by the general formula (I) is represented by the general formula (V):

(In the formula, R ⁴ represents the same or different substituted or unsubstituted alkyl group having 1 to 8 carbon atoms in total, and R ⁵ represents the same or different substituted or unsubstituted alkyl group having 6 carbon atoms in total. -8 represents an aromatic group, and X represents a siloxane structure bonded to Si existing in a skeleton in the same polyorganosiloxane or in another polyorganosiloxane through an oxygen atom, and a ⁴ , b ⁴ , c ⁴ , a ⁵ and c ⁵ mean the mole fraction in the random copolymer, 0.04 ≦ a ⁴ ≦ 0.24, 0.05 ≦ b ⁴ ≦ 0.25, 0.40 ≦ c, respectively. ⁴ ≦ 0.80, 0.01 ≦ a ⁵ ≦ 0.15, 0.05 ≦ c ⁵ ≦ 0.15, and 0.05 ≦ a ⁴ + a ⁵ ≦ 0.25 and a ⁴ + b ⁴ + C ⁴ + a ⁵ + c ⁵ = 1. The inorganic clear coating composition of Claim 1 which is a silanol group containing polyorganosiloxane represented by these.   A colored pigment-containing coating is formed on the object to be coated to form a colored pigment-containing coating, and the inorganic clear coating composition according to claim 1 is applied onto the colored pigment-containing coating to form an inorganic coating. A multi-layer coating film forming method for forming a clear coating film, wherein the object to be coated is immersed in 1 L of ion-exchanged water having a pH of 6.7 and left to stand at 23 ° C. for 24 hours. A method for forming a multilayer coating film, which is a ceramic building material or a slate building material for roofs, having a pH of 8.5 or higher after removing the object to be coated.   A multilayer coating film formed by the multilayer coating film forming method according to claim 6.