JP2823249B2 - Primer for inorganic substrate - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a primer for an inorganic substrate. More specifically, the present invention relates to a primer for an inorganic substrate based on a composition comprising a specific silyl group-containing vinyl polymer and a curing catalyst which may be contained.

[Conventional technology]

2. Description of the Related Art In recent years, inorganic plate-like products for housing have been widely developed from cement-extruded plates having a dense surface to porous ALC.

In general, inorganic base materials such as inorganic plate-like materials have very high water absorption compared to plastic base materials, etc., and have properties such as strong alkalinity.When applying to inorganic base materials, apply a primer. A method has been adopted in which a final coating is performed after adjusting them.

Among the primers used as described above, epoxy primers have relatively favorable properties.

[Problems to be solved by the invention]

However, in the case of the epoxy primer, an inorganic substrate having a dense surface does not have sufficient anchoring effect on the substrate and has poor adhesion, while a porous substrate such as ALC does not. The primer is required to have low shrinkage or elasticity due to its fragile surface, but epoxy primers have the drawback that they are hard and cannot be said to have low shrinkage.

In addition, primer coating is performed not only on the factory line but also on site, and in winter it may be used at a low temperature of about 5 ° C. However, epoxy-based primers have good curability at such low temperatures. Therefore, development of a primer having good low-temperature curability instead of an epoxy-based primer is desired.

[Means for solving the problem]

The present inventors have conducted intensive studies to solve the problems in the epoxy primer, and as a result, have completed the present invention.

That is, the present invention relates to a method for producing a glass, wherein the main chain is substantially composed of a vinyl polymer chain, and at least one silicon-containing group bonded to a terminal and / or side chain with a hydrolyzable group per molecule; Transition point (T
g) is a silyl group-containing vinyl polymer having a temperature of 10 ° C. or less, and the chief examiner consists essentially of a vinyl polymer chain, and a silicon-containing group bonded to a terminal and / or a side chain with a hydrolyzable group in one molecule. Has at least one glass transition point (Tg) of 30 ° C
The present invention relates to a primer for an inorganic substrate based on a composition comprising the following silyl group-containing vinyl polymer and a curing catalyst which may be contained.

〔Example〕

As a component of the composition serving as a base of the primer of the present invention, a silicon-containing group (hereinafter, referred to as a hydrolyzable group) having a main chain substantially consisting of a vinyl polymer chain and having a terminal and / or a side chain bonded to a hydrolyzable group. A silyl group-containing vinyl polymer having at least one decomposable silyl group in one molecule, and having a glass transition point (Tg) of 10 ° C. or less, which is mainly composed of a vinyl polymer chain; A silyl group-containing vinyl polymer having at least one silicon-containing group bonded to a hydrolyzable group at the terminal and / or side chain in one molecule and having a glass transition point (Tg) of 30 ° C. or lower is used. You.

When the main chain of the silyl group-containing vinyl polymer is substantially composed of a vinyl polymer chain, a segment other than a segment composed of vinyl monomer units, such as a segment having a urethane bond or a siloxane bond in the main chain. Is a segment of
This means that the silyl group-containing vinyl polymer may be contained within a range that does not substantially impair the properties of the vinyl polymer, and generally, 50 atomic% of the atoms constituting the main chain.
Even if a segment other than the segment comprising the vinyl monomer unit is contained within the range of the degree or less, the characteristics as the vinyl polymer are not substantially impaired. Since the main chain is substantially composed of a vinyl polymer, durability,
It becomes a primer with excellent chemical resistance. In addition, when a top coat such as acrylic urethane, acrylic silicon, or one-component acrylic is applied after the primer is applied, an effect that adhesion to the pliers is extremely good can be obtained.

The silicon-containing group bonded to the hydrolyzable group means that the group (X) bonded to the silicon atom (Si) is SiOH by hydrolysis.
And a group containing a group that can be decomposed into XH.Since such a group is contained in the silyl group-containing vinyl polymer, a silanol group is generated as long as water is present, and a siloxane The characteristic arises that bonds can be created.

The term "having at least one hydrolyzable silyl group in one molecule at the terminal and / or side chain of the silyl group-containing vinyl polymer" means that one molecule is present at the terminal or side chain of the main chain of the polymer. Has at least one, and preferably two or more, hydrolyzable silyl groups. Since it has at least one hydrolyzable silyl group per molecule, it has a high molecular weight or gels in the presence of moisture, generates a chemically stable siloxane bond, and improves the chemical resistance of the cured product. In addition, since the hydrolyzable silyl group has a good affinity for the inorganic base material and causes a cross-linking reaction due to the presence of moisture, the coating film has good adhesion to the inorganic base material, and the equipment has a water absorbing property. Even in this case, there is obtained an effect that the moisture is not adversely affected and blistering or peeling does not occur.

The molecular weight per hydrolyzable silyl group present in the silyl group-containing vinyl polymer is 1,000 to 2
It is preferably about 000 from the viewpoint of chemical resistance and adhesion.

The molecular weight of the silyl group-containing vinyl polymer is not particularly limited, and usually about 2,000 to 30,000, preferably about 3,000 to 25,000 is used.

Further, when the glass transition point (Tg) of the polymer is as low as 10 ° C. or less, a characteristic that the polymer has low shrinkage occurs, and when the Tg is as high as 30 ° C. or less, chemical resistance and water resistance are obtained. In addition, there is a feature that the reinforcing property of the base material is improved.

The silyl group-containing vinyl polymer as described above is obtained by, for example, copolymerization of a vinyl monomer and a hydrolyzable silyl group-containing monomer (hereinafter, also referred to as a silyl group-containing monomer). May be polymerized so as to include a segment formed by a urethane bond, a siloxane bond, or the like in a part of the polymer.

The vinyl monomer is not particularly limited, but specific examples thereof include, for example, methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate,
Stearyl (meth) acrylate, benzyl (meth) acrylate, cyclohexyl (meth) acrylate, trifluoroethyl (meth) acrylate, pentafluoropropyl (meth) acrylate, polycarboxylic acids (maleic acid, fumaric acid, itaconic acid, etc.) and carbon Numbers 1-20
Of unsaturated carboxylic acids such as diesters or half esters with linear or branched alcohols of the formula: aromatic hydrocarbons such as styrene, α-methylstyrene, chlorostyrene, styrenesulfonic acid, 4-hydroxystyrene and vinyltoluene Vinyl compounds; vinyl esters and allyl compounds such as vinyl acetate, vinyl propionate and diallyl phthalate; vinyl compounds containing nitrile groups such as (meth) acrylonitrile; vinyl compounds containing epoxy groups such as glycidyl (meth) acrylate; dimethylaminoethyl (meth) ) Amino group-containing vinyl compounds such as acrylate, diethylaminoethyl (meth) acrylate, vinylpyridine and aminoethyl vinyl ether; (meth) acrylamide, itaconic acid diamide, α
-Ethylacrylamide, methacrylamide, crotonamide, maleic diamide, fumaric diamide, N-
Amide group-containing vinyl compounds such as vinylpyrrolidone, N-butoxymethyl (meth) acrylamide, N, N-dimethylacrylamide, N-methylacrylamide, acryloylmorpholine; 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) Acrylate, 2-hydroxyethyl vinyl ether, N-methylol (meth) acrylamide, Alonix 5700 (manufactured by Toa Gosei Chemical Industry Co., Ltd.), Placcel FA-1, Placcel FA-
4. Hydroxyl-containing vinyl compounds such as Placcel FM-1 and Placcel FM-4 (manufactured by Daicel Chemical Industries, Ltd.);
Acrylic acid, maleic acid, fumaric acid, itaconic acid, salts thereof (alkali metal salts, ammonium salts, amine salts, etc.), unsaturated carboxylic acids such as maleic anhydride, acid anhydrides or salts thereof; vinyl methyl ether, chloride vinyl,
Other vinyl compounds such as vinylidene chloride, chloroprene, propylene, butadiene, isoprene, maleimide, N-vinylimidazole, and vinyl sulfonic acid.

When producing a silyl group-containing vinyl polymer having a low Tg of 10 ° C. or less, a homopolymer such as butyl acrylate or 2-ethylhexyl (meth) acrylate as a vinyl monomer is used. It is sufficient to use many vinyl monomers with low Tg,
When a product having a high Tg such as 30 ° C. or higher is produced, a vinyl monomer having a high Tg of a homopolymer such as methyl methacrylate, ethyl methacrylate, or styrene may be used in many cases.

The silyl group-containing monomer is not particularly limited, but specific examples thereof include, for example, And so on.

The method for producing a silyl group-containing vinyl polymer from the silyl group-containing monomer and the vinyl monomer is not particularly limited, and examples thereof include JP-A Nos. 54-36395 and 57-3.
No. 6109, can be manufactured according to the method shown in the same 58-157810, etc., but the solution polymerization using an azo radical initiator such as azobisisobutyronitrile is easy to handle the initiator, It is most preferable because the polymerization reaction mixture can be used as it is.

In the production, n-dodecyl mercaptan, t-dodecyl mercaptan, n-butyl mercaptan, γ-mercaptopropyltrimethoxysilane, γ
—Mercaptopropyltriethoxysilane, γ-mercaptopropylmethyldimethoxysilane, γ-mercaptopropylmethyldiethoxysilane, (CH ₃ O) ₃ Si—S—
The molecular weight can be adjusted by using a chain transfer agent such as S-Si (OCH ₃ ) ₃ and (CH ₃ O) ₃ Si-S ₈ -Si (OCH ₃ ) ₃ .

In particular, when a chain transfer agent having a hydrolyzable silyl group in the molecule, for example, γ-mercaptopropyltrimethoxysilane, the hydrolyzable silyl group can be introduced into the terminal of the silyl group-containing vinyl polymer.

Examples of the polymerization solvent include hydrocarbons (toluene, xylene, n-hexane, cyclohexane, etc.), acetates (ethyl acetate, butyl acetate, etc.), alcohols (methanol, ethanol, isopropanol, n-butanol, etc.), ethers Non-reactive solvents such as ethyl cellosolve, butyl cellosolve, cellosolve acetate, ketones (methyl ethyl ketone, ethyl acetoacetate, acetylacetone, diacetone alcohol, methyl isobutyl ketone, acetone, etc.) can be used without particular limitation. .

As the other component of the composition serving as the base of the primer of the present invention, a curing catalyst for the silyl group-containing vinyl polymer may be used. When the curing catalyst is used, the curing of the silyl group-containing vinyl polymer is accelerated as compared with when the curing catalyst is not used. In particular, even at a low temperature such as about 5 ° C. in winter, the curing is promoted, the crosslinking is easily formed, and the remarkable effect that the physical properties as a primer are rapidly exhibited is obtained.

Specific examples of the curing catalyst include organic tin compounds such as dibutyltin dilaurate, dibutyltin dimaleate, dioctyltin dilaurate, dioctyltin dimaleate, and tin octylate; phosphoric acid, monomethyl phosphate, monoethyl phosphate, monobutyl phosphate Phosphoric acid esters such as monooctyl phosphate, monodecyl phosphate, dimethyl phosphate, diethyl phosphate, dibutyl phosphate, dioctyl phosphate, and didecyl phosphate; alkyl titanates; organic aluminum; acidic compounds such as maleic acid and patoluene sulfonic acid; Hexylamine,
Amines such as di-2-ethylhexylamine, N, N-dimethyldodecylamine and dodecylamine; and alkaline compounds such as sodium hydroxide and potassium hydroxide. These curing catalysts may be used alone,
Two or more kinds may be used in combination.

In the present invention, a composition serving as a base of the primer of the present invention is prepared from the silyl group-containing vinyl polymer and a curing catalyst that may be contained.

When a curing catalyst is used, the mixing ratio of the silyl group-containing vinyl polymer and the curing catalyst in the composition is as follows:
Although it differs depending on the type of the curing catalyst and cannot be specified unconditionally, it is usually 0.01 to 20 parts, preferably about 0.01 to 10 parts, per 100 parts of the hydrolyzable silyl group-containing vinyl polymer (parts by weight, hereinafter the same). It is.

Further, the silyl group-containing vinyl polymer is prepared so as to contain a silyl group-containing vinyl polymer having a Tg of 10 ° C. or less and a silyl group-containing vinyl polymer having a Tg of 30 ° C. or more. When applied to a porous inorganic substrate such as ALC, a silyl group-containing vinyl polymer having a Tg of 10 ° C or less is used to improve properties such as low shrinkage, and a silyl group-containing vinyl polymer having a Tg of 30 ° C or more. The polymer is effective for improving the reinforcing property and water resistance, and is preferable.

In this case, the weight ratio of the silyl group-containing vinyl polymer having a Tg of 10 ° C. or lower to the silyl group-containing vinyl polymer having a Tg of 30 ° C. or higher is preferably about 1/9 to 8/2 by weight ratio.

 Tg can be calculated by the following Fox equation.

(Wherein, Tg _i is Tg of i component, m _i represents the weight fraction of the i component.) In preparation of the silyl group-containing vinyl polymer and consists also be curing catalyst be contained composition There is no particular limitation, and these may be mixed and prepared by a usual method. At this time, if necessary, hydrocarbons such as toluene and xylene; acetates such as butyl acetate; alcohols such as methanol and isopropanol; other ethers; and solvents such as ketones may be used.

A dehydrating agent may or may not be added to the composition, but it is more preferable to add a dehydrating agent in order to ensure stability that does not cause a problem even when used repeatedly and stability over a long period of time.

Specific examples of such a dehydrating agent include, for example, methyl orthoformate, ethyl orthoformate, methyl orthoacetate, ethyl orthoacetate, methyltrimethoxysilane, γ-methacryloxypropyltrimethoxysilane, vinyltrimethoxysilane, methylsilicate, Examples include hydrolyzable ester compounds such as ethyl silicate.

In the above description, the hydrolyzable ester compound is blended at the time of preparing the composition, but may be used also as a solvent in addition to before the polymerization of the silyl group-containing vinyl polymer, or may be added after the polymerization is completed. Further, the composition may be blended when the primer of the present invention is prepared using this composition.

The composition contains one or more amines having a silicon-containing group bonded to at least one hydrolyzable group in one molecule (hereinafter also referred to as silyl group-containing amine) as an adhesion improving component. It can be contained. The silyl group-containing amine can be contained. When the silyl group-containing amine is contained, for example, when the primer of the present invention is applied to an inorganic substrate having a dense surface such as a cement extruded plate, the adhesion is significantly improved. Can be obtained.

Specific examples of the silyl group-containing amine include, for example, γ-aminopropyltriethoxysilane, γ-aminopropyltrimethoxysilane, N-β-aminoethyl-γ
A silane coupling agent such as aminopropyltrimethoxysilane; a silane coupling agent containing the amino group and ethylene oxide, butylene oxide, epichlorohydrin, epoxidized soybean oil, Yuka Shell Epoxy Co., Ltd.
Reaction products with an epoxy group-containing compound such as Epikote 828 or Epikote 1001 manufactured by Epson Corporation.

The amount of the silyl group-containing amine to be used is preferably about 1 to 500 parts, more preferably about 5 to 200 parts, per 100 parts of the silyl group-containing vinyl polymer.

When the silyl group-containing amine is used in combination with the silyl group-containing vinyl polymer, when an alkyl alcohol having 1 to 4 carbon atoms is added, stabilization when the composition contained in the container is repeatedly used or used for a long time, It is effective for preventing thickening and curing during storage. Specific examples of the alkyl alcohol having 1 to 4 carbon atoms include methanol, ethanol, n-propyl alcohol, isopropyl alcohol, n-butanol and sec-butanol. The amount of the alkyl alcohol to be used is preferably about 1 to 200 parts with respect to 100 parts of the silyl group-containing amine, and 5 to 100 parts.
Parts is more preferred.

In the above description, the silyl group-containing amine is blended at the time of preparing the composition, but it goes without saying that it may be blended at the time of preparing the primer of the present invention.

The composition used in the present invention thus prepared is
Generally, it has a resin concentration and a solution viscosity or a diluent viscosity suitable for a usual coating method, for example, brush coating or spray coating.

The primer of the present invention may be composed of only the above-mentioned composition, but depending on the use, additives such as various pigments, dyes, anti-settling agents and leveling agents; nitrocellulose, cellulose such as cellulose acetate butyrate; It may be prepared by adding a resin such as an alkyd resin, an acrylic resin, a vinyl chloride resin, a chlorinated propylene resin, a chlorinated rubber, and polyvinyl butyral. In particular, the addition of a pigment is effective in discriminating a portion coated with a primer.

For example, when the primer of the present invention is used as a primer for ALC, the ratio of the silyl group-containing vinyl polymer having a Tg of 10 ° C. or less to the silyl group-containing polymer having a Tg of 30 ° C. or more is expressed by weight. The primer blended in about 1/9 to 8/2 is used as a base resin, and primers such as those colored with titanium oxide improve the balance between low shrinkage, water resistance, and substrate reinforcement. preferable. When used as a primer for a cement extrusion molded board, 5-200 parts of a silyl group-containing amine is added to 100 parts of a silyl group-containing vinyl polymer, and the silyl group-containing amine to be used is 100 parts. 5 to 100 parts of an alkyl alcohol having 1 to 4 carbon atoms based on parts, and a primer of such a formulation colored with titanium oxide or the like has good adhesion to a base material and stability of viscosity during storage. Is preferred from the viewpoint of good

The primer of the present invention thus prepared generally has a resin solid content concentration suitable for a general coating method such as brush coating or spray coating, and a property of having a solution viscosity or a diluent viscosity. Since these characteristics also vary depending on the type and amount of the component to be contained, the application, and the like, it is natural that the characteristics may be out of the above range.

As described above, the primer of the present invention is applied to an inorganic base material, and the water absorption of the inorganic equipment can be adjusted.

Since the primer of the present invention is based on a silyl group-containing vinyl polymer, the hydrolyzable silyl groups present in the polymer are hydrolyzed by moisture to generate SiOH groups, and the SiOH groups present on the surface of the inorganic base material. By reacting with the group, a strong bond is generated, so that the adhesiveness is good even for a dense material such as a cement extruded plate. In addition, since the hydrolysis of the hydrolyzable silyl group and the subsequent formation of siloxane bonds occur even at a low temperature such as about 5 ° C. in winter, for example, it cannot be used at a low temperature in a conventional epoxy primer. Is eliminated. Furthermore, since the main chain of the silyl group-containing vinyl polymer is composed of a soft main chain as compared to the epoxy resin, which is a vinyl polymer chain, even if applied to a porous and fragile surface such as ALC, There is no problem such as in the case of a primer.

Specific examples of the inorganic substrate include, for example, concrete, mortar, ALC, cellular concrete, brick, tile,
Examples include slate, calcium silicate board, porcelain, tile, stone, wood chip cement board, cement extruded board, slag, and gypsum cement board.

The coating method of the primer of the present invention is not particularly limited, and the amount of the coating varies depending on the denseness of the surface of the inorganic base material to be coated, water absorption, etc., the composition of the primer, etc., and cannot be specified unconditionally. For a substrate with a dense surface such as a molded plate, generally 10 to 100 g in solid content
/ m ² , and in the case of a substrate having a porous surface such as ALC, the solid content is generally about 50 to 200 g / m ² .

As described above, the inorganic substrate coated with the primer of the present invention is excellent in chemical resistance, reinforcing property, water resistance or adhesion with a topcoat material, and is suitably used as an exterior material having excellent long-term durability. Can be used.

Next, the primer of the present invention will be described based on examples.

Synthesis Examples 1 to 3 360 g of xylene was charged into a reactor equipped with a stirrer, a thermometer, a nitrogen introduction tube, a dropping funnel, and a cooling tube, and heated to 110 ° C. Thereafter, a solution of 295 g of butyl acrylate, 579 g of methyl methacrylate, 117 g of γ-methacryloxypropyltrimethoxysilane, 9 g of acrylamide and 8.5 g of azobisisobutyronitrile was continuously added to the reactor over 3 hours. After the addition of the monomer, a solution of 2 g of azobisisobutyronitrile and 140 g of toluene prepared separately was added over 1 hour, and after 1 hour, polymerization was carried out to obtain a solution of the silyl group-containing vinyl resin (a-1). I got

The nonvolatile content of the obtained resin solution was 63%. The number average molecular weight of the resin measured by GPC was 15,000. Titanium oxide (CR manufactured by Ishihara Sangyo Co., Ltd.) was used to make the silyl group-containing vinyl resin PWC 5% and paint solid concentration 50%.
-90) was dispersed to prepare a white enamel. Dispersion was performed for 2 hours with a paint shaker using glass beads.

On the other hand, two kinds of hydrolyzable silyl group-containing vinyl resins (a) were prepared in the same manner as in the above (Synthesis Example 1) except that the proportions of the monomer and azobisisobutyronitrile were changed as shown in Table 1. -2) and (a-3) were obtained to prepare a white enamel.

Synthesis Example 4 100 g of xylene, 80 g of methanol, Epicoat 828 were placed in a reactor equipped with a stirrer, thermometer, nitrogen inlet tube, and cooling tube.
56 g of bisphenol A type epoxy resin (manufactured by Yuka Shell Epoxy Co., Ltd.), A1100 (γ-manufactured by Nippon Unicar Co., Ltd.)
Aminopropyltriethoxysilane) (64 g) was charged and reacted at room temperature for 30 minutes and then at 70 ° C. for 2 hours to obtain a silyl group-containing amine solution (a-4). (A-4) shows a reaction solution containing methanol or xylene.

When the obtained reaction product was analyzed by infrared spectroscopy, the absorption of the epoxy group at 910 cm ^-1 had disappeared.

Reference Examples 1 to 4 and Comparative Reference Example 1 A mortar plate prepared using standard sand of JIS R 5201
Each of 10 parts of the white enamel obtained in Synthesis Examples 1 to 3 and dioctyl tin maleate added in the amount shown in Table 2 and a commercially available epoxy primer were dried to a thickness of about 10 μm. It was then coated, but cured at 5 ° C. After 2 hours, the painted sample is completely submerged in water and
, And visually observed for any change in appearance.
The results are shown in Table 2.

Examples 1 and 2, Reference Examples 5 to 7 and Comparative Example On the entire surface of an ALC plate (manufactured by Nippon Test Panel Industry Co., Ltd.),
The primers shown in Table 3 were applied to a thickness of about 10 μm after drying, allowed to stand at room temperature for 7 days, and then completely immersed in water. The occurrence of cracks) was visually observed, and the number of abnormal cycles and the weight change after 5 cycles were measured. The results are shown in Table 3.

The freeze-thaw test was performed at -20 ° C for 3 hours and at 60 ° C for 3 hours.
Performed as a cycle.

Reference Examples 8 to 11 and Comparative Reference Example 2 A primer having a composition shown in Table 4 was applied to an extruded cement board (trade name: Asrock manufactured by Nozawa Co., Ltd.) so that the thickness after drying was about 10 μm. After leaving the sample at room temperature for 7 days, the sample was completely immersed in water.
A freeze-thaw test was performed in the same manner as in Examples 7 to 7, and the occurrence of blisters or cracks was visually observed to determine the number of cycles in which these occurred. At the end of 50 cycles, an adhesion test was performed. The results are shown in Table 4.

A1120 in Table 4 represents N-β-aminoethyl-
γ-aminopropyltrimethoxysilane. Also,
The adhesion was evaluated by a cellophane tape peeling method using a 1 ml Goban.

[Effect of the Invention] When the primer of the present invention is used, when applied to a porous and fragile surface such as ALC, which is a drawback of using a conventional epoxy primer, the coating film easily cracks and is durable. It is possible to solve the drawbacks that the properties are poor, the drawback that the surface is inadequately adhered to a dense surface such as a cement extruded plate, and the drawback that it cannot be used at a low temperature.

Claims (6)

(57) [Claims] (1) a main chain consisting essentially of a vinyl polymer chain, having at least one silicon-containing group bonded to a hydrolyzable group at a terminal and / or a side chain in one molecule, and having a glass transition A silyl group-containing vinyl polymer having a point (Tg) of 10 ° C. or less, a main chain consisting essentially of a vinyl polymer chain, and a silicon-containing group bonded to a terminal and / or a side chain with a hydrolyzable group. Primer for inorganic base material based on a composition comprising a silyl group-containing vinyl polymer having at least one in one molecule and having a glass transition point (Tg) of 30 ° C. or higher and a curing catalyst which may be contained . 2. The primer according to claim 1, comprising at least one amine having at least one silicon-containing group bonded to a hydrolyzable group in a molecule. 3. The primer according to claim 2, comprising an alkyl alcohol having 1 to 4 carbon atoms. 4. The primer according to claim 1, which contains a pigment. 5. The primer according to claim 1, wherein the inorganic substrate is ALC. 6. The primer according to claim 2, wherein the inorganic substrate is a cement extruded plate.