JPH0331370A - Primer for inorganic substrate - Google Patents

Abstract

PURPOSE:To provide the subject primer consisting of a vinyl polymer containing a specific silyl group and a curing catalyst, giving a coating film having excellent durability on a porous surface, exhibiting sufficient adhesivity even to a dense surface such as extrusion molded cement plate and usable even at a low temperature. CONSTITUTION:The objective primer contains (A) 100 pts.wt. of a vinyl polymer containing silyl group, having a main chain composed of a vinyl polymer chain and having at least one Si-containing group bonded to a hydrolyzable group on the terminal and/or side chain per one molecule (the vinyl monomer is e.g. butyl acrylate for forming a polymer having a glass transition point Tg of <=10 deg.C or is e.g. methyl methacrylate for forming a polymer having a Tg of >=30 deg.C), (B) 0.01-20 pts.wt. of a curing catalyst and, preferably, (C) at least one kind of amine having at least one Si-containing group bonded to a hydrolyzable group in the molecule.

Description

[Detailed description of the invention] [Industrial application field] The present invention is a primer for inorganic substrates. Regarding 2.

More specifically, a primer for inorganic substrates is based on a composition comprising a specific silyl group-containing vinyl polymer and a curing catalyst that may be contained. Regarding 2.

[Conventional technology]

In recent years, a wide range of inorganic plate-like materials for residential use have been developed, ranging from cement insert-molded plates with dense surfaces to porous ALC.

In general, inorganic base materials such as inorganic plate-like materials have characteristics such as extremely high water absorption and strong alkalinity compared to plastic base materials, so when painting on inorganic base materials, a primer is used. The method used is to apply a second coat, adjust them, and then apply a topcoat.

Primer as above. Among the primers used as No. 2, epoxy primers have relatively favorable characteristics. There are 2.

[Problem to be solved by the invention]

However, the epoxy primer mentioned above. In the case of 2, for inorganic substrates with dense surfaces, the anchoring effect to the substrate is insufficient and the adhesion is poor, whereas for porous substrates such as ALC, the surface is fragile. Primer on. Epoxy primers are required to have low shrinkage or elasticity. No. 2 has the drawbacks of being hard and not having low shrinkage.

Also, primer. 2. Painting is not only done on the factory line, but also on-site, and is sometimes used at temperatures as low as 5 degrees Celsius in winter, using an epoxy-based primer. 2 has poor curing properties at such low temperatures and is an epoxy-based primer. A primer with good low-temperature curing properties to replace No. 2. 2 is desired to be developed.

[Means to solve the problem]

The present inventors developed the above-mentioned epoxy-based primer. As a result of intensive research to solve the problem in 2, the present invention has been completed.

That is, the present invention provides a silyl group-containing polymer whose main chain is substantially composed of a vinyl polymer chain and which has at least one silicon-containing group in one molecule bonded to a hydrolyzable group at the terminal and/or side chain. A primer for inorganic substrates based on a composition comprising a vinyl polymer and a curing catalyst that may be contained. Regarding 2.

〔Example〕

Primer of the present invention. As one component of the base composition of No. 2, silicon-containing groups (hereinafter referred to as hydrolyzable A silyl group-containing vinyl polymer having at least one silyl group (also referred to as a silyl group) in one molecule is used.

The main chain of the silyl group-containing vinyl polymer essentially consists of a vinyl polymer chain means that the main chain is not a segment made of vinyl monomer units, such as a segment having a urethane bond or a siloxane bond in the main chain. This means that the segment may be contained in the silyl group-containing vinyl polymer to the extent that it does not substantially impair the properties of the vinyl polymer, and generally contains 50 atom% of the atoms constituting the main chain.
Even if segments other than segments consisting of vinyl monomer units are contained within a certain range, the properties as a vinyl polymer will not be substantially impaired. As the main chain is essentially made of vinyl polymer, it has excellent durability and
Primer with excellent chemical resistance. It becomes 2.

Also, primer. When a top coat such as acrylic urethane, acrylic silicone or one-component acrylic is applied on top of the coating of 2, the effect of extremely good adhesion with pliers can be obtained.

The silicon-containing group bonded to the hydrolyzable group means that the group (X) bonded to the silicon atom (Si) becomes S by hydrolysis.
This is a group that contains a group that can be decomposed into 10H and , the characteristic that siloxane bonds can be formed occurs.

Furthermore, the end of the silyl group-containing vinyl polymer and (
or) Having at least one hydrolyzable silyl group in one molecule in the side chain means that the polymer has at least one hydrolyzable silyl group in one molecule at the end of the main chain or in the side chain.
This means that it has at least one, preferably two or more, hydrolyzable silyl groups per molecule. Since it has at least one hydrolyzable silyl group per molecule, it increases its molecular weight or gels in the presence of moisture, producing chemically stable siloxane bonds and improving the chemical resistance of the cured product. In addition, hydrolyzable silyl groups have good affinity for inorganic substrates and cause a crosslinking reaction in the presence of water, so the coating film has good adhesion to inorganic substrates and the substrate is water-absorbing. Even if it is a product, it will not be adversely affected by the moisture, and it will have the effect of not causing blistering or peeling.

The molecular weight per hydrolyzable silyl group present in the silyl group-containing vinyl polymer is 1.000.
It is preferable that it is about 20,000 from the viewpoint of chemical resistance and adhesion.

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

Further, there is no particular limitation on the glass transition point (Tg) of the polymer, but when the Tg is low, for example, 10°C or less, the polymer has a characteristic of low shrinkage.
When Tg becomes high, such as 30° C. or higher, characteristics such as improved chemical resistance, water resistance, and reinforcing properties of the base material occur.

The above-mentioned silyl group-containing vinyl polymer can be prepared by, for example, a vinyl monomer and a hydrolyzable silyl group-containing monomer (
(hereinafter also referred to as a silyl group-containing monomer), and in this case, the polymer may be polymerized so that a portion of the main chain or side chain includes a segment formed by a urethane bond, a siloxane bond, or the like.

The vinyl monomer is not particularly limited, but specific examples include 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 ( Esters of unsaturated carboxylic acids such as meth)acrylates, diesters or half esters of polycarboxylic acids (maleic acid, fumaric acid, itaconic acid, etc.) and linear or branched alcohols having 1 to 2 carbon atoms; styrene, α- Aromatic hydrocarbon vinyl compounds such as methylstyrene, chlorostyrene, styrene sulfonic acid, 4-hydroxystyrene, and vinyltoluene; vinyl esters and allyl compounds such as vinyl acetate, vinyl propionate, and diallyl phthalate; (meth)acrylonitrile, etc. Nitrile group-containing vinyl compounds; Epoxy group-containing vinyl compounds such as glycidyl (meth)acrylate; Amino group-containing vinyl compounds such as dimethylaminoethyl (meth)acrylate, diethylaminoethyl (meth)acrylate, vinylpyridine, aminoethyl vinyl ether; ) Acrylamide, itaconic acid diamide, α
-ethyl acrylamide, methacrylamide, crotonamide, maleic diamide, fumaric diamide, N-
Vinyl compounds containing amide groups 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, Aronix 5700
(manufactured by Toagosei Chemical Industry Co., Ltd.), Placel PA
-1, Placel PA-4, Placel P
Hydroxyl group-containing vinyl compounds such as H-ISPlaccel PH-4 (manufactured by Daicel Chemical Industries, Ltd.): (meth)acrylic acid, maleic acid, fumaric acid, itaconic acid, and their salts (alkali metal salts, ammonium salts, amine salts, etc.)
, unsaturated carboxylic acids such as maleic anhydride, acid anhydrides or their salts; vinyl methyl ether, vinyl chloride, vinylidene chloride, chlorobrene, propylene, butadiene,
Examples include other vinyl compounds such as isoprene, maleimide, N-vinylimidazole, and vinyl sulfonic acid.

For example, a vinyl polymer containing a silyl group has a Tg of 10
When producing products with a low Tg, such as below ℃, butyl acrylate, 2-
If the homopolymer has a low Tg, such as ethylhexyl (meth)acrylate, it is sufficient to use a large amount of methyl It is sufficient to use a large amount of vinyl monomers whose homopolymers have a high Tg, such as methacrylate, ethyl methacrylate, and styrene.

Further, the silyl group-containing monomer is not particularly limited, but specific examples thereof include, for example, CI+2 -CII
91(OC113)3, C112-CIISICI
s, 113 CH2= ClIC0O(CH2)3 Sl (OC
I! 3) 2, C)+2 = ClICOO(C
H2)35i(OCIIz)3,113CH2-CHCOO(CH2)3St(J2,C
H2-C)tcOO(CH2)35iCfs,
Hs C)+2- C(CH3)COO(CH2)381(
OCH3)2, CH2-C(CH3)COO(C)
12) 35l(OC1+3)s, CH3Cl-12-C<CHs)Coo(CI42)38
ICI2, C)+2 = C(C)13)C
OO(CHz)3SICIs, CH2-C(C
H3) COO(CH2)i Sl (OC2H5)3,
CH3 CH2-C(CH3)COO(CH2)3 Sl(O
Examples include C2H5)2.

There is no particular limitation on the method for producing a silyl group-containing vinyl polymer from the silyl group-containing monomer and vinyl monomer, and for example, JP-A No. 54-36395, JP-A No. 57-38109, JP-A No. 58-157810. Although it can be produced according to the method shown in the publication, solution polymerization using an azo radical initiator such as azobisisobutyronitrile is easier to handle, and the polymerization reaction product mixture can be used as is. This is the most preferable because it is possible.

During the above production, n-dodecylmercaptan, t-dodecylmercaptan, ropetylmercaptan, γ-mercaptopropyltrimethoxysilane, γ-
Mercaptopropyltriethoxysilane, γ-mercaptopropylmethyldimethoxysilane, γ-mercaptopropylmethyljethoxysilane, (CH30)x 5t-8-8-81 (OCHx)3
, (CI+30)33l-8s-91(OCH3)
Molecular weight can be adjusted using chain transfer agents such as z.

In particular, if a chain transfer agent having a hydrolyzable silyl group in the molecule, such as γ-mercaptopropyltrimethoxysilane, is used, the hydrolyzable silyl group can be introduced at the end of the silyl group-containing vinyl polymer.

Hydrocarbons (toluene, xylene,
n-hexane, cyclohexane, etc.), acetic acid esters (ethyl acetate, butyl acetate, etc.), alcohols (methanol, ethanol, isopropanol, n-butanol, etc.), ethers (ethyl cellosolve, butyl cellosolve, cellosolve acetate, etc.), Any non-reactive solvent such as ketones (methyl ethyl ketone, ethyl acetoacetate, acetylacetone, diacetone alcohol, methyl isobutyl ketone, acetone, etc.) can be used without particular limitation.

Primer of the present invention. As another component of the base composition of No. 2, 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 compared to when it is not used. In particular, curing is accelerated even at low temperatures of about 5℃ in winter, and crosslinks are easily formed.
Primer. The remarkable effect of 2 is that the physical properties develop quickly.

Specific examples of the curing catalyst include organic tin compounds such as dibutyltin dilaurate, dibutyltin dilaurate, dioctyltin dilaurate, dioctyltin dilaurate, and tin octylate; phosphoric acid, monomethyl phosphate, monoethyl phosphate, and Phosphate esters and alkyl titanates such as butyl phosphate, monooctyl phosphate, monodecyl phosphate, dimethyl phosphate, diethyl phosphate, dibutyl phosphate, dioctyl phosphate, and didecyl phosphate; Organoaluminium; Acidic acids such as maleic acid and para-toluenesulfonic acid Compounds; amines such as hexylamine, di-2-ethylhexylamine, N,N-dimethyldodecylamine, and dodecylamine; alkaline compounds such as sodium hydroxide and potassium hydroxide; and the like. These curing catalysts may be used alone, or 2
More than one species may be used in combination.

In the present invention, the primer of the present invention is made of the silyl group-containing vinyl polymer and the curing catalyst that may be contained. A base composition of No. 2 is prepared.

When a curing catalyst is used, the blending ratio of the silyl group-containing vinyl polymer and the curing catalyst in the composition varies depending on the type of curing catalyst and cannot be unconditionally specified. Usually 0.01 to 20 parts per 100 parts (parts by weight, same hereinafter) of vinyl polymer,
Preferably, " is about 0.01 to 10 parts.

In addition, when the silyl group-containing vinyl polymer is prepared to contain 7g of the silyl group-containing vinyl polymer of 10°C or less and 7g of the silyl group-containing vinyl polymer of 30°C or higher, especially ALC, etc. When applied to a porous inorganic base material, 7g of silyl group-containing vinyl polymer at 10°C or lower is used to improve properties such as low shrinkage.
A silyl group-containing vinyl polymer having a temperature of 30° C. or higher is effective for improving reinforcing properties, water resistance, etc., and is therefore preferred.

In this case, the ratio of the silyl group-containing vinyl polymer having a weight of 7 g at 10 DEG C. or lower to the silyl group-containing vinyl polymer having a temperature of 7 g at 30 DEG C. or higher is preferably about 1/9 to 8/2 by weight.

Note that Tg can be calculated using the following Fax formula.

Tg Tg.

(In the formula, Tg of one component represents the weight fraction of component i.) Method for preparing a composition comprising the silyl group-containing vinyl polymer and a curing catalyst that may be contained. There are no particular limitations, and these may be prepared by mixing them in a conventional manner. At this time, if necessary, solvents such as hydrocarbons such as toluene and xylene; acetic esters such as butyl acetate; alcohols such as methanol and isopropanol; other ethers; and ketones may be used.

A dehydrating agent may or may not be included in the composition, but it is preferable to include a dehydrating agent in order to ensure stability that does not cause problems even after repeated use and long-term stability.

Specific examples of such dehydrating agents include 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 explanation, the hydrolyzable ester compound is blended at the time of preparing the composition, but it may be added before the polymerization of the silyl group-containing vinyl polymer to serve as a solvent, or it may be added after the completion of the polymerization. This composition can even be used as a primer of the present invention. It may be blended when preparing 2.

The composition contains, as an adhesion improving component, an amine having a silicon-containing group bonded to at least one hydrolyzable group in one molecule (hereinafter also referred to as a silyl group-containing amine).
A species or two or more species can be included. When the silyl group-containing amine is contained, for example, the primer of the present invention. When No. 2 is applied to an inorganic substrate having a dense surface such as a cement extrusion plate, the effect of significantly improving adhesion can be obtained.

Specific examples of the silyl group-containing amine include γ
-aminopropyltriethoxysilane, γ-aminopropyltrimethoxysilane, N-β-aminoethyl-γ-
A silane coupling agent such as aminopropyltrimethoxysilane and a silane coupling agent containing an amino group and an epoxy group such as ethylene oxide, butylene oxide, epichlorohydrin, epoxidized soybean oil, or Epicoat 828 or Epicoat 1001 manufactured by Yuka Shell Epoxy ■. Examples include reactants with other compounds.

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

When the silyl group-containing amine is used in combination with a silyl group-containing vinyl polymer, adding an alkyl alcohol having 1 to 4 carbon atoms can stabilize the composition when it is used repeatedly or over a long period of time in a container. Effective in preventing thickening and hardening 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 5eC-butanol. The amount of the alkyl alcohol used is preferably about 1 to 200 parts per 100 parts of the silyl group-containing amine, and about 5
About 100 parts is more preferable.

In the above explanation, the silyl group-containing amine is blended at the time of preparing the composition, but in the primer of the present invention. It is a matter of course that the ingredients may be blended at the time of preparation of the ingredients.

The composition thus prepared for use in the present invention generally has a resin concentration and solution viscosity or dilute solution viscosity suitable for conventional coating methods, such as brush coating or spray coating.

Primer of the present invention. 2 may be composed only of the above composition, but depending on the use, additives such as various pigments, dyes, antisettling agents, leveling agents, nitrocellulose,
It may be prepared by adding cellulose such as cellulose acetate butyrate; resins such as alkyd resins, acrylic resins, vinyl chloride resins, chlorinated propylene resins, chlorinated rubber, and polyvinyl butyral. In particular, the addition of pigment is a primer. This is effective in identifying the parts painted with 2.

For example, the primers of the invention. 2 is a primer for ALC. When used as 2, the weight ratio of a silyl group-containing vinyl polymer with a Tg of 10°C or less and a silyl group-containing polymer with a Tg of 30°C or higher is about 1/9 to 872. A primer with a formula such as a base resin and colored with titanium oxide. 2 is preferable from the viewpoint of improving the balance between low shrinkage, water resistance, and reinforcing properties of the base material. Primer for cement extrusion boards. 2
When used as a silyl group-containing vinyl polymer, 5 to 200 parts of the silyl group-containing amine is added to 100 parts of the silyl group-containing vinyl polymer.
A primer with a formulation such as one to which 5 to 100 parts of an alkyl alcohol having 1 to 4 carbon atoms is added based on 0 parts and colored with titanium oxide or the like. No. 2 is preferable from the viewpoints of good adhesion to the substrate and good viscosity stability during storage.

The primer of the present invention thus prepared. 2 is
In general, it has the characteristics of having a resin solid content concentration and solution viscosity or diluted solution viscosity that are suitable for general painting methods such as brush painting and spray painting, but the types and amounts of ingredients contained and the purpose etc. Since these characteristics also change depending on the characteristics, it is natural that the characteristics may be outside the range of the above characteristics.

The primer of the present invention as described above. 2 is applied to an inorganic base material to adjust the water absorbency of the inorganic base material.

Primer of the present invention. Since 2 is based on a vinyl polymer containing silyl groups, the hydrolyzable silyl groups present in this polymer are hydrolyzed by moisture to generate 5IOH groups, which react with the 5tall groups present on the surface of the inorganic base material. By doing so, a strong bond is formed, and the adhesion is good even to a dense object such as an extruded cement plate. Further, since the hydrolysis of the hydrolyzable silyl group and the subsequent formation of siloxane bonds occur even at a low temperature of about 5° C. in winter, for example, conventional epoxy primers. The problem in No. 2 that it cannot be used at low temperatures is solved. Furthermore, since the main chain of the silyl group-containing vinyl polymer is a vinyl polymer chain, which is softer than that of epoxy resins, epoxy resins can be applied to porous and fragile surfaces like ALC. Primer. Problems like those in case 2 do not occur.

Specific examples of the inorganic base material include concrete, mortar, ALC, cellular concrete, brick, tile,
Slate, calcium silicate board, ceramic, tile, stone, wood chip cement board, cement extrusion board, slab, gypsum cement board, etc.

Primer of the present invention. There are no particular restrictions on the second coating method, and the amount of coating depends on the density and water absorption of the surface of the inorganic substrate to be coated, as well as the primer. Although it cannot be defined unconditionally as it varies depending on the composition of
- long/M, and in the case of a base material with a porous surface such as ALC, the solid content is generally about 50 to 200 g/nf.

The primer of the present invention as described above. The inorganic base material coated with No. 2 has excellent chemical resistance, reinforcing properties, water resistance, and adhesion with top coating materials, and can be suitably used as an exterior material with excellent long-term durability.

Next is the primer of the present invention. 2 will be explained based on an example.

Synthesis Examples 1 to 3 380 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 the temperature was heated to 110°C.
heated to. After that, butyl acrylate 29! zr
A solution containing 579 g of methyl methacrylate, 7 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 7-mer, add 2 g of azobisisobutyronitrile prepared separately and 140 g of toluene. The lI solution was added over a further 1 hour, and after another 1 hour, polymerization was carried out to obtain a solution of the silyl group-containing vinyl resin (a-1).

The nonvolatile content concentration of the resin solution obtained was 63%. In addition, the number average molecular weight of this resin by GPC method is 15.000.
Met. Titanium oxide (Ishihara Sangyo ■
A white enamel was prepared by dispersing CR-90') produced by the company. For dispersion, use glass beads and use a paint shaker for 2
I did it for an hour.

On the other hand, except that the proportions of monomers and azobisisobutyronitrile used were changed as shown in Table 1,
) A white enamel was prepared by preparing solutions of two types of hydrolyzable silyl group-containing vinyl resins (a-2) and (a-3).

[Margin below]

Synthesis Example 4 100g of xylene, 80g of methanol (1 Epicor) in a reactor equipped with a stirring device, thermometer, nitrogen introduction tube, and cooling tube
828 (Bisphenol A manufactured by Yuka Shell Epoxy■
mold epoxy resin) 58g.

64 g of ^1100 (gamma-aminopropyltriethoxysilane manufactured by Nippon Unicar Co., Ltd.) was charged and reacted at room temperature for 30 minutes and then at 70°C for 2 hours to obtain a solution (a-4) of silyl group-containing amine. Note that (a-4) indicates a reaction solution containing methanol and xylene.

When the obtained reaction product was analyzed by infrared spectroscopy, it was found that the absorption of the epoxy group at 910 am-' had disappeared.

Examples 1 to 4 and Comparative Example I To a mortar plate prepared using JIS R5201 standard sand, 10 parts of the white enamel obtained in Synthesis Examples 1 to 3 and dioctyltin maleate were added in the amounts listed in Table 2. and commercially available epoxy primers. Paint each of 2 so that the thickness after drying is about 1 OIA,
It was immediately cured at 5°C. After 2 hours, the painted samples were completely immersed in water and stored at 5° C. for 1 day, after which they were visually observed for any change in appearance. The results are shown in Table 2.

[Margin below]

Examples 5 to 9 and Comparative Example 2 The third layer was applied to the entire surface of the ALC board (manufactured by Nippon Test Panel Industries)
Primers shown in the table. 2 was applied to a thickness of approximately 10 sheets after drying, left at room temperature for 7 days, the sample was completely immersed in water, and the following freeze-thaw test was conducted to determine whether there was any change in appearance (occurrence of cracks). The presence or absence was visually observed, and the number of cycles in which an abnormality occurred and the weight change rate after 5 cycles were measured.

The results are shown in Table 3.

The freeze-thaw test was conducted at -20°C for 3 hours and at 60°C for 3 hours as one cycle.

[Margin below]

Examples 1O to 13 and Comparative Example 3 A primer having the composition shown in Table 4 was applied to an extruded cement board (trade name: Asrock manufactured by Nozawa Co., Ltd.). The thickness of 2 after drying is about 10. The sample was applied to a concentration of i7m, left at room temperature for 7 days, then completely immersed in water, and a freeze-thaw test was conducted in the same manner as in Examples 5 to 5, and the presence or absence of blisters or cracks was visually observed. The number of these cycles that occurred was determined. Further, an adhesion test was conducted at the end of 50 cycles. The results are shown in Table 4.

Note that Al120 in Table 4 is N-β-aminoethyl-γ-aminopropyltrimethoxysilane. Further, the adhesion was evaluated by a cellophane tape peeling method of 111-th grid.

[Margin below]

[Effects of the Invention] Primer of the present invention. 2 uses a conventional epoxy primer. The disadvantage of using 2 is that when applied to a porous and fragile surface like ALC, the coating film tends to crack and has poor durability, and the surface is dense like cement extrusion board. It is possible to understand the drawbacks such as insufficient adhesion to objects and the inability to use at low temperatures.

Claims (1)

[Scope of Claims] 1. A silyl group whose main chain consists essentially of a vinyl polymer chain and which has at least one silicon-containing group in one molecule bonded to a hydrolyzable group at the terminal and/or side chain. A primer for an inorganic substrate based on a composition comprising a vinyl polymer and a curing catalyst that may be contained. 2 As the silyl group-containing vinyl polymer, at least a silyl group-containing vinyl polymer having a glass transition point (Tg) of 10°C or lower and a silyl group-containing vinyl copolymer having a glass transition point (Tg) of 30°C or higher. The primer according to claim 1, comprising: 3. The primer according to claim 1 or 2, containing at least one amine having at least one silicon-containing group in its molecule bonded to a hydrolyzable group. 4 Claim 3 containing an alkyl alcohol having 1 to 4 carbon atoms
Primer as described. 5. The primer according to claim 1, 2 or 3, containing a pigment. 6. The primer according to claim 2, wherein the inorganic base material is ALC. 7. The primer according to claim 3, wherein the inorganic base material is a cement extrusion plate.