JPH0645767B2 - Elastic vinyl-based primer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) In construction, paints and caulking materials are often used. In recent years, the number of repair works has increased with the aging of buildings, but in this case, since the surface of the base material is often weakened, there is a problem such as poor adhesion of the coating material. The present invention relates to a general-purpose primer that enhances the adhesion between a base material and a coating material such as paint or caulking material. The primer of the present invention is particularly effective for silicone-based or acrylic-based top coating materials and caulking materials.

(Prior Art) Conventionally, primers such as chlorinated rubber-based, chlorinated paraffin-based, chlorinated polyolefin-based, and acrylic-based resin-soluble types, or urethane-based, epoxy-based, silicon-based, etc. reaction-curing types , Various things are used. However, each of these has drawbacks in any of adhesion with coating materials, weather resistance, penetration into base materials, etc.
Not necessarily satisfied. The resin-soluble type has a relatively large molecular weight and is inferior in permeability to a fragile substrate, so that only the surface can be reinforced. On the other hand, the reaction-curing type has a low molecular weight during coating and has a high molecular weight due to the subsequent reaction, so its permeability is good, but its re-coatability after curing and its adhesion to different materials are poor. .

(Problems to be Solved by the Invention) Accordingly, the present invention provides a versatile primer having improved penetration into the surface of a substrate, recoatability, weather resistance, etc. For the purpose of convenience, it is a one-pack type moisture-curable one, and is intended to overcome the above problems (penetration, weather resistance, adhesion, recoatability, etc.).

(Means for Solving Problems) When used as a primer and also expected to reinforce the fragile surface of the substrate, a low molecular weight polymer is required to improve permeability. Further, in order to strengthen the brittle base material, it is necessary to make it into a high molecular weight after permeation.

Therefore, in the present invention, it was found that when a hydrolyzable-Si group is introduced into the side chain in order to increase the molecular weight, the reaction proceeds at room temperature due to moisture, which is effective. The primer layer may be regarded as an adhesive layer, but this layer must be flexible and tough. That is, if it is too hard, the adhesive layer becomes brittle, and if it is too soft, it lacks strength.
Both are destroyed by the primer layer. It has been found that it is effective to combine the hard component and the soft component in a certain specific ratio and to use acrylonitrile together for imparting the toughness.

That is, the present invention provides (a) a hard component (which does not have a hydrolyzable silane group itself, and has a Tg measured by a differential scanning calorimeter of its homopolymer).
Of 5 to 80 parts by weight (wherein acrylonitrile is 5 to 30 parts by weight), (b) a soft component (which itself has a hydrolyzable silane group). And its homopolymer Tg by differential scanning calorimeter
A vinyl monomer having a temperature of -20 ° C or less) in an amount of 95 to 20 parts by weight, and (c) a hydrolyzable silane group-containing vinyl monomer component,
0.5 to 0.5 as Si based on the total weight of (a) + (b) + (c) above
It is a copolymer consisting of 10 parts by weight of only 10% by weight, and has a molecular weight of 3,000 to 50,000.
An elastic vinyl-based primer containing the copolymer as a main component is provided.

In order to obtain permeability, it is preferable that the molecular weight is small, but considering the physical properties of the generated primer, a certain degree of polymerization is required, so specifically 3,000 to 50,000 is required, and 15,000 to 25,000 is required. It is suitable.

As a method for introducing the hydrolyzable-Si group into the copolymer, it is convenient to use a copolymerization of a radically polymerizable unsaturated organic silane compound. This unsaturated organosilane compound is
It is a polymerizable silane compound represented by the following general formula.

R ₁ -Si (R ₂ ) aX _3-a (wherein R ₁ is an organic residue having a radically polymerizable double bond, R ₂ is a hydrocarbon group having 1 to 10 carbon atoms, X is an alkoxy group, acyloxy group). Group or aminooxy group, a is 0
Or 1 or 2. ) Most preferably, as these polymerizable silane compounds,
It is a vinyl monomer containing a hydrolyzable silane group, and specific examples thereof include -methacryloxypropyltrimethoxysilane, -methacryloxypropylmethyldimethoxysilane, vinyltrichlorosilane, vinyltrimethoxysilane and vinylmethyldimethoxy. Examples include silane, vinyldimethylmethoxysilane, vinyltriethoxysilane, vinylmethyldiethoxysilane, vinyltripropoxysilane, and vinyltris (βmethoxyethoxy) silane.

The hard component for obtaining a tough layer as the primer layer does not have a hydrolyzable silane group itself, and its homopolymer has a Tg measured by a differential scanning calorimeter (DSC).
Is preferably a vinyl-based monomer having a temperature of 30 ° C. or higher, and examples thereof include secondary butyl methacrylate, tertiary butyl acrylate, ethyl methacrylate, methyl methacrylate (Tg = 38 ° C.), vinyl acetate (Tg = 3
0 ° C), isopropyl methacrylate, styrene (T
g = 105 ° C.), p-methylstyrene and the like.
In addition to this, radical polymerization is possible, and it can be used as long as the polymer Tg of its own homopolymer is 30 ° C. or higher.

Acrylonitrile (Tg =
(105 ° C.) makes the resulting film very tough.

As a soft component which gives flexibility to the primer, a vinyl-based monomer having no hydrolyzable silane group itself and having a Tg of the homopolymer thereof of −20 ° C. or less measured by a differential scanning calorimeter. Are preferred, and examples thereof include butyl acrylate (Tg = -52 ° C), 2-ethylhexyl acrylate (Tg = -68 ° C), 2-ethylbutyl acrylate, and ethyl acrylate. Other than the above, any monomer having radical polymerizability and having a Tg of its own homopolymer of −20 ° C. or lower can be used.

The solvent used for the polymerization reaction is xylene, ethyl acetate, toluene, methyl ethyl ketone, 1,1,1-trichloroethane, dioxane, 2-ethoxyethyl acetate, etc. to dissolve the resulting copolymer and hydrolyze the side chain. Any solvent can be used as long as it is inert to the silane group. Polymerization catalyst
Azo-based catalysts such as 2,2'-azobisisobutyronitrile and 2,2'-azobis-2methylbutyronitrile are preferred.

The polymerization operation is carried out at a rate of 60 to 100 ° C. at a ratio such that the copolymer concentration after completion of the polymerization is 10 to 70% by weight.

The hard component in the obtained polymer is 5 to 80%, the soft component is 95 to 20%, and when the acrylonitrile in the hard component is in the range of 5 to 30%, it is best used alone or in combination. Give a result.

A curing catalyst may or may not be used, but the use will speed up curing. As the catalyst, an organic tertiary amine type catalyst,
There is an organometallic compound type catalyst, triethylamine, N, N
-Dimethylcyclohexylamine, dibutyltin dilaurate and the like can be used.

Examples will be given below to describe the present invention in more detail.

(Example 1) 86.5 g of butyl acrylate, 9.6 g of acrylonitrile,
-Methacryloxypropyltrimethoxysilane 3.9
g, azobisisobutyronitrile 1.0 g, toluene 10
0 g of a mixed solution is prepared, and 50 g of the mixed solution is put in a 0.5-necked 4-neck separable flask and heated to 90 ° C. with stirring by a mantle heater. A reflux condenser equipped with a calcium tube for absorbing moisture at the tip of the flask, a dropping funnel at one neck, a nitrogen introducing tube at one neck, and a thermometer at the other neck One hour before, nitrogen gas was blown from the nitrogen inlet to replace the reaction atmosphere with nitrogen. The remaining mixed solution is put into a dropping funnel, and the temperature is raised to 90 ° C., followed by dropping for 1 hour. After the dropping is completed, the reaction is continued for 2 hours and cooled to complete the reaction.

Drying at 110 ℃ for 3 hours, non-volatile content 49.8%, viscosity
2,150 cp of product was obtained. Dilute this with toluene,
It was used as a primer with a nonvolatile content of 15%.
In use, dibutyltin dilaurate was used as a curing catalyst in an amount of 1% based on the solid content of the primer. As the top coating material, resin-containing cement mortar manufactured by Showa High Polymer Co., Ltd. was used. The resin-containing cement mortar was prepared according to the following prescription.

The surface of a commercially available mortar plate (70 mm × 70 mm × 25 mm) was previously subjected to a belt sander to remove dust, and then a primer was applied so that the coating amount was 150 g / m ² .

After this was placed in a standard condition of 20 ± 1 ° C. and 65 ± 5% relative humidity (RH) for 24 hours, the prepared resin-containing cement mortar was applied to a size of 4 cm × 4 cm and a thickness of 1 mm, and immediately 20
It was aged for 7 days under the conditions of ± 1 ° C. and 100% RH, and further continued for 14 days under the standard condition of 20 ± 1 ° C. and 65 ± 5% RH. After that, attach the attachment to the top coating surface with epoxy resin, and use Autograph (Shimadzu Corporation)
Was used to conduct a tensile test. (Loading speed 5 mm / min) The result reached 27.5 kg / cm ² , and no interfacial fracture occurred,
The mortar board cracked and the base material was destroyed.

(Examples 2 to 6) The same polymerization and test method as in Example 1 was used, and 5 of Examples 2 to 6 was used.
It carried out about the point.

(Comparative Example 1) The same operation as in Example 1 was repeated except that butyl acrylate was changed to 57.7 g and acrylonitrile was changed to 38.4 g.

When the amount of acrylonitrile component increased, the copolymer became insoluble in the solvent, and the whole reaction solution gelled and did not show fluidity. Testing as a primer was not possible.

(Comparative Examples 2 to 5) Comparative Example 2 does not contain a hard component.

Comparative Example 3 does not contain a hydrolyzable silane compound.

Comparative Example 4 does not contain a soft component.

Comparative Example 5 does not use the primer itself.

None of these could give satisfactory results.

The above results are summarized in Table 1.

(Function) As described above, in the elastic vinyl-based primer of the present invention, since the molecular weight is appropriate, the penetration into the base material is good, and the hydrolyzable -Si group is stably present in the side chain of the copolymer.
Room temperature curability after evaporation of the solvent is effective. In the primer of the present invention, since the primer layer that cures at room temperature is a tough elastic body, it forms a strong adhesive layer with the overcoat material. Coexisting acrylonitrile is effective for improving the adhesive strength, and in the test of the adhesive strength, the base material or the overcoat layer undergoes cohesive failure. Since the primer of the present invention has the above characteristics, it effectively acts as a primer not only on a new base material surface but also on an aged fragile base material surface.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification number Office reference number FI technical display location C08F 222/10 MME 7242-4J 230/08 MNU 7242-4J

Claims (1)

[Claims] 1. A hard component (a vinyl-based monomer which does not have a hydrolyzable silane group itself and has a Tg of 30% or more by differential scanning calorimetry of its homopolymer). 5-8
0 part by weight (however, acrylonitrile is 5 to 30 parts by weight), (b) a soft component (which does not have a hydrolyzable silane group in itself, and is a differential scanning calorimeter of its homopolymer) Tg
A vinyl monomer having a temperature of -20 ° C or less) in an amount of 95 to 20 parts by weight, and (c) a hydrolyzable silane group-containing vinyl monomer component,
0.5 to 0.5 as Si based on the total weight of (a) + (b) + (c) above
It is a copolymer consisting of 10 parts by weight of only 10% by weight, and has a molecular weight of 3,000 to 50,000.
An elastic vinyl-based primer whose main component is the copolymer.