JPS6330571A - Moisture curing paint resin composition - Google Patents

Abstract

PURPOSE:To obtain the title resin compsn. having excellent weather resistance and improved flexibility at low temp., by using a mixture of a fluorocopolymer having an alkoxysilane group on its side chain and a curing catalyst as a main component. CONSTITUTION:A resin compsn. is mainly composed of a mixture obtd. by mixing 100 pts.wt. fluorocopolymer (A) having an alkoxysilane group on its side chain obtd. by reacting a fluorocopolymer having hydroxyl groups or hydroxyl and carboxyl groups on its side chain with 0.1-10 mol (per mol of hydroxyl group in the fluorocopolymer) of an isocyanate-functional silane, with not more than 3 pts.wt. curing catalyst (B) and optionally, not more than 100 pts.wt. polyorganosiloxane (C) having at least two silicon atoms attached to a silanol group or an alkoxy group per molecule.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is based on a fluorine-containing copolymer having an alkoxysilane group in the side chain, which has excellent weather resistance, and has various mechanical properties, especially flexibility at low temperatures. The present invention relates to a moisture-curable coating resin composition which has significantly improved properties and is suitable for coating wood, metal, slate, tiles, plastics, etc.

[Prior Art] In recent years, soft plastics have been increasingly used as materials for self-help bumpers and the like. Due to the nature of the product, such materials are required to maintain flexibility even at extremely low temperatures. This is because when applying paint to soft plastic, if the paint is less flexible than the plastic it is made from, cracks in the paint film will often propagate to the material when it undergoes deformation such as bending. The paint used on such soft plastics needs to be sufficiently flexible even at low temperatures.

Moreover, in recent years, the need for weather resistance for paints applied to such soft plastics has increased, and there is a desire to develop paints that have excellent weather resistance and also have sufficient flexibility at low temperatures. .

It has been known that coatings with excellent weather resistance can be obtained by crosslinking fluorine-containing copolymers containing hydroxyl groups, but no excellent crosslinking method has been found.

That is, as a crosslinking method for a fluorine-containing copolymer containing a water M group in the side chain (1) a polyisocyanate compound or 2) a hydroxyl group contained in the copolymer and a hydroxyl group contained in the copolymer at room temperature or under heating.
(Polyalkoxymethyl) React with melamine or 3
) The only known method is to introduce a double bond and then polymerize an ethylenically unsaturated monobase that is copolymerizable with the η-introduced double bond.

However, method 1) required three days at room temperature to cure, and there was a risk that it would react with moisture in the air and cause foaming. 2
) method, it is possible to cure within a few minutes, but
It required a high temperature of 200°C.

In method 3), in the first step, a fluorine-containing copolymer containing a water M group is reacted with an unsaturated acid anhydride to introduce a double bond. There is a method of copolymerizing an ethylenically unsaturated mono-omega substance that can be copolymerized with the double bond introduced in the second step of the first step, but it requires two steps for crosslinking and is said to be cumbersome due to the many steps. There were drawbacks.

Furthermore, because the coating film obtained by the above-mentioned crosslinking reaction is hard, its mechanical properties, especially its flexibility at low temperatures, are insufficient, making it unsuitable for use as a coating material for coating soft plastics. .

In such cases, improvements have been made in the prior art by mixing resins that have sufficient flexibility at low temperatures, but fluorine-containing copolymers containing hydroxyl groups in their side chains are Because of its poor compatibility with other resins, it has been impossible to achieve sufficient flexibility at low temperatures by mixing with other resins.

[Problem to be Solved by the Invention 1] As a result of intensive research into methods for overcoming the above drawbacks, the present inventors found that isocyanate-functional silane is added to a fluorine-containing copolymer containing a water M group in the side chain. By reacting in one step, the mechanical properties of the fluorine-containing copolymer containing the hydroxyl group, especially the flexibility at low temperatures, can be improved. It was discovered that it was possible to maintain the same 1-reversion resistance as before, and this '91 version was completed.

[Means for Solving the Problems] That is, the present invention (8) combines a fluorine-containing copolymer containing a hydroxyl group or a hydroxyl group and a carboxyl group in the side chain and an isocyanate-functional silane into a fluorine-containing copolymer. (B) Curing is applied to 100 parts of a fluorine-containing copolymer having an alkoxysilane group in the side chain obtained by reacting isocyanate-functional silane at a ratio of 0.1 to 10 moles per mole of hydroxyl group. 3 parts or less of catalyst and optionally (C) 1 oois of polyorganosiloxane having at least 2 silicon atoms bonded to silanol groups or alkoxy groups in 1 molecule.
The above-mentioned problems have been solved by providing a resin composition for moisture-curable coatings, which is characterized in that the main component is a mixture containing .

[Function] The moisture-curable coating resin composition of the present invention has (
A) Characteristics of the component: By synthesizing a fluorine-containing copolymer with alkoxysilane groups pendant on the side chains, it cures by reacting with moisture in the air at room temperature, and completes curing in about 24 hours. This method takes advantage of the excellent effect of

Each component used in the present invention will be specifically explained below.

Examples of the fluorine-containing copolymer containing a hydroxyl group or a water M group and a carboxyl group in the side chain used in the present invention include fluoroolefins such as chlorotrifluoroethylene, trifluoroethylene, and tetrafluoroethylene, hydroxyethyl vinyl ether, and hydroxyethyl vinyl ether. Hydroxy alkyl vinyl ethers such as vinyl ether, hydroxybutyl vinyl ether, and hydroxyhexyl vinyl ether, and alkyl vinyl ethers or cyclohexyl vinyl ethers such as ethyl vinyl ether, propyl vinyl ether, butyl vinyl ether, hexyl vinyl ether, and those in which hydrogen of these alkyl groups or vinyl groups has been replaced with fluorine. It is a copolymer obtained by copolymerizing ethylene, propylene, isobutylene, vinyl chloride, nylidene chloride, vinyl acetate, n-butyrate, methyl methacrylate, etc. as copolymerized components. Good too.

Fluoroolefin is present in the above polymer in an amount of 40 to 60 mol%.
and hydroxyalkyl vinyl ether has a hydroxyl value (
#JKOII/g) is preferably used in a range of 3 to 10, particularly 5 to 70.

If the amount of fluoroolefin is too small, the effect of improving weather resistance will be reduced, and it may be difficult to introduce it in too much.

The hydroxyl value is 3 to 100, preferably 5 to 7°. When the hydroxyl value is less than 3, it is difficult for the isocyanate-functional silane to react completely, and when it exceeds 100, the use of hydroxyalkyl vinyl ether increases, which tends to limit the solubility in organic solvents. From the viewpoint of solubility in organic solvents, the hydroxyalkyl vinyl ether is preferably used in an amount of 15 mol % or less.

Moreover, it is preferable to use cyclohexyl vinyl ether and alkyl vinyl ether in a total amount of 5 to 60 mol % in the above copolymer.

If the amount of cyclohexyl vinyl ether and alkyl vinyl ether is too small, the above-mentioned copolymer will be difficult to dissolve in the solvent, and if it is too large, the layer in which fluoroolefin or hydroxyalkyl vinyl ether is used will be reduced.

Further, it is preferable from the viewpoint of characteristics that cyclohexyl vinyl ether and alkyl vinyl ether are used in an amount of 5 to 45 mol %, respectively. It is preferable that other components be used in the above copolymer in an amount of 30 mol % or less.

Furthermore, fluorine-containing copolymers include those into which carboxyl groups have been introduced by polymer reaction.

Examples of commercially available fluorine-containing copolymers include Lumiflon LF100, Lr200, and Lr3 manufactured by Asahi Kozuko.
00.

Examples include Lr400, which can of course be used in the present invention.

The isocyanate-functional silane used in the present invention is γ-isocyanatopropyltrimethoxysilane, or a reaction product of an alkoxysilane having active hydrogen and a polyvalent isocyanate (hereinafter abbreviated as reaction product (△)). One example is shown by the following formula.

The reaction product (△) used in the present invention is obtained by reacting an alkoxysilane having active hydrogen in an amount of 1 to 18 mol, preferably 1 to 1.4 mol, per 1 mol of a polyvalent incyanate compound. be synthesized. Synthesis of reaction product (A) t) An alkoxysilane having an active hydrogen is added dropwise to a polyvalent isocyanate compound in a solvent such as ethyl acetate, methyl ethyl ketone, or toluene to avoid the reaction.

Alternatively, the reaction may be carried out without using a solvent. In this reaction, it is preferable to use a urethanization catalyst such as a tertiary amine or a tin organic compound.

Examples of alkoxysilanes having active hydrogen include γ-mercaptotrimethoxysilane, N-β-(aminoethyl)-
γ-aminopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, N-β-(aminoethyl)
-γ-aminopropylmethyldimethoxysilane and the like.

Examples of polyvalent isocyanate compounds include 2.4-tolylene diisocyanate, 2.6-tolylene diisocyanate, 2.4-)-lylene diisocyanate and 2.6-tolylene diisocyanate.
- Mixture with lylene diisocyanate 1-, diphenylmethane diisocyanate, 1,5-naphthylene diisocyanate, rose phenylene diisocyanate, xylylene diisocyanate, isophorone diisocyanate, 1
．． Examples include 6-hexamethylene diisocyanate, hydrogenated xylylene diisocyanate, and oligomers having isocyanate groups at both ends, but aliphatic polyvalent isocyanates are preferred.

The reaction between the fluorine-containing copolymer and the isocyanate-functional alkoxysilane is carried out in a solvent such as ethyl acetate, methyl ethyl ketone, toluene, etc. by adding 0.1 to 0.1 to 1 mol of the isocyanate-functional alkoxysilane to 11 moles of water of the fluorine-containing copolymer.
It is carried out in a proportion of 10 mol, preferably 0.5 to 5 mol. At this time, it is preferable to use a urethanization catalyst such as a tertiary amine or an organic compound of tin.

Through the above reaction, the hydroxyl group in the fluorine-containing copolymer and the isocyanate group in the isocyanate-functional alkoxysilane undergo an addition reaction, and the fluorine-containing copolymer has a moisture-curable alkoxysilane group pendant on the side chain due to a urethane bond. A polymer is obtained.

The reaction molar ratio between hydroxyl groups in the fluorine-containing copolymer and isocyanate-functional alkoxysilane varies depending on the purpose of use, so it cannot be determined unconditionally, but it is The appropriate amount of alkoxysilane is 0.1 to 10 mol, preferably 0.5 to 5 mol. That is, if the amount of isocyanate-functional alkoxysilane is less than 0.1 mole, the moisture curing properties will be insufficient and the resin will not be able to fully exhibit its original performance. Also, 10
If the amount is more than 1 molar, not only will the effect of increasing a be no longer recognized, but during moisture curing, it will react with the water present in the system, generate carbon dioxide gas, and foam, causing bubbles to form in the coating film. There is a thing.

The organopolysiloxane used as necessary in the present invention is an organopolysiloxane having at least two silicon atoms bonded to a silanol group or an alkoxy group in one molecule, and is linear or branched,
The upper limit is not particularly limited, but is preferably C8 or less. Two or more silicon atoms bonded to an alkoxy group must be present, and two of them are preferably present at positions as far apart as possible in the molecule.

As a unit constituting this organoborisiloxane (R' 0)3SiO-.

(R’　O)2　R3i　O.

(R'O)RSiO(R'0)2--R8i
C1-12CH2Si(R2)O-.

Examples include siloxane units such as.

Here, R is a substituted or unsubstituted single-stroke hydrocarbon group, such as an alkyl group such as a methyl group, an ethyl group, or a propyl group, a vinyl group, an allyl group, an alkenyl group such as hexenyl 14, a cyclohexyl group, a cyclohebutyl group, etc. Cycloalkyl groups, phenyl groups, tolyl groups, aryl groups such as xylyl groups, aralkyl groups such as benzyl groups, phenylethyl groups, chlorophenyl groups, tetrachlorophenyl groups, chloroethyl groups, pentafluoropropyl groups, trifluoropropyl groups, etc. It is preferable that 50% or more of the components as a whole (including halogen-substituted monovalent hydrocarbon groups, etc.) be methyl groups. Also, R' has 6 carbon atoms.
The following monovalent hydrocarbon groups include methyl group, ethyl group, propyl group, butyl group, vinyl group, cyclohexyl group, methoxyethyl group, chloroethyl group, phenyl group, and particularly preferably methyl group and ethyl group. , is a propyl group.

Among these organopolysiloxanes, those listed below are preferably used.

Terminal silanol polydimethylsiloxane, terminal silanol diphenylsiloxane, terminal diphenylsilanol polydimethyl-diphenylsiloxane, h -0-8i -OH h terminal methoxy polydimethylsiloxane, terminal ethoxy polydimethylsiloxane, -〇02H5 terminal methoxydiphenylsiloxane, terminal ethoxy Diphenylsiloxane, polyjethoxysilane, triethoxysilyl modified poly(1,2 polybutadiene)
, methyltris(tri-S-butoxysiloxanyl)silane.

The polyorganosiloxane is used in an amount of 1 or less per 100 parts by weight of the fluorine-containing copolymer. 10(i
Even if it is added in excess of the fiffi portion, not only will the effect of increasing the hardness no longer be observed, but the excellent weather resistance that is a feature of fluororesins will not be sufficiently maintained.

The compositions of the present invention may be cured with or without the use of a silanol curing catalyst. When curing catalysts are used, examples include alkyl titanates: organosilicon titanates; carboxylic acids such as octyl'Patin, dibutyltin laurate and dibutyltin maleate, dibutyltin phthalate, etc. Amine salts such as ethylhexoate and the like, as well as acidic and salt-based catalysts, are suitable. Furthermore, when the fluorine-containing copolymer having an alkoxysilane group in its side chain contains a carboxyl group, it is not necessary to add a curing catalyst. Further, when a curing catalyst is used, it is appropriate to add it in an amount of 3 parts or less per 100 parts of the fluorine-containing copolymer.

The moisture-curable coating composition obtained according to the present invention can be diluted with a specific solvent to form a lacquer coating.

When used as a paint in this way, inorganic pigments such as titanium white, cadmium yellow, and carbon black, and pigments such as phthalocyanine and azo pigments can be added as necessary.

It is preferable to use such a pigment by thoroughly kneading it in advance with a resin composition for a moisture-curable coating. The above-mentioned coatings are particularly suitable as coatings for automobiles, architecture, or structures such as wood, molds, plastics, slate, tiles, etc.

[Example] Next, the present invention will be explained in more detail with reference to Examples. In the examples, parts are parts by weight and % is revision percentage.

Example 1 Fluorine-containing copolymer containing hydroxyl groups [hydroxyl value 52, molecular weight approximately 80,000 (gel permeation analysis: tested with standard polystyrene) copolymer of trifluoroethylene, hydroxyalkyl vinyl ether, and alkyl vinyl needle xylene solution [solid content 60%, Lumiflon LF
-200 (Asahi Glass Kan, trade name) 100 parts, isocyanatopropyltriethoxysilane (NUC silane coupling agent Y -9030, made by Nippon Unicar Aji, structural formula 0 formula % 10% xylene solution of butyltin dilaurate 01 parts (hydroxyl group A mixture of 1 mol of isocyanatopropyltriethoxysilane per 1 mol of hydroxyl groups in the fluorine-containing copolymer containing 1 mol of isocyanatopropyltriethoxysilane was stirred at 80"C for 6 hours to complete the reaction. Then, after cooling to room temperature, 30 parts of xylene was added to obtain a silane-modified fluorine-containing copolymer solution with a nonvolatile content of 50%.

A paint having the following composition was prepared using the obtained silane-modified fluorine-containing copolymer solution.

Silane-modified fluorine-containing copolymer solution 60 parts Rudil-type butane dioxide pigment (manufactured by Teikoku Kako@J, JR-602) 25 parts Cellosolve acetate 10 parts Oxygen
10 parts of the obtained paint was applied to a mild steel plate to a dry film thickness of 40μ, and then dried at room temperature for 1 hour to form a smooth and glossy (
A cured coating film with a 60 degree specular gloss value of 90 was obtained.

The resulting paint was then applied to a polyurethane sheet to a dry film thickness of 40 μm, and dried at room temperature to obtain a smooth and glossy cured tt7 IQ.

When the resulting coating film was subjected to a bending test at -30°C using a 1 inch diameter round bar with the coating side facing outward, the coating showed sufficient low temperature resistance without cracking. Ta. Then, when an accelerated weathering test was conducted for 2000 hours using a sunshine weather meter, it showed excellent weatherability with a retention rate of 93%.

Example 2 Fluorine-containing copolymer xylene solution (same as Example 1) 100 parts Isocyanatopropyltriethoxysilane 333 t dibutyltin dilaurate (10% xylene solution) 01 parts (hydroxyl group in fluorine-containing copolymer 1 (Ratio of 3 moles of isocyanatopropyltriethoxysilane to mol) The same procedure as in Example 1 was carried out except for the above composition.

The obtained paint was applied to a mild steel plate to a dry film thickness of 40μ, and then dried at room temperature for 1 hour to create a smooth and glossy (
A 60 degree specular gloss value of 89) I11' coated film was obtained.

The coated paint was then applied to a polyurethane sheet to a dry film thickness of 40 μm, and dried at air temperature to obtain a smooth and glossy cured film. The obtained coating film was used in Example 1.
When a bending test was conducted in the same manner as above, there were no cracks in the paint film.
It showed sufficient low temperature flexibility. Then, when an accelerated weathering test was conducted for 2000 hours using a Zanshine weather meter, it showed excellent weatherability with a gloss retention rate of 93%.

Comparative Example 1 A xylene solution of a fluorine-containing copolymer containing a hydroxyl group (same as in Example 1) 100 parts Rutile titanium dioxide (above Example 1) 25 parts Dibutyltin dilaurate (10% xylene solution) 0.1 10 pieces of Rotrube acetate
Shin Shin
30 parts 7.3 parts of isophorone diisocyanate was added to the paint having the above composition. The obtained paint was applied to a mild steel plate to a dry film thickness of 40μ, and then heated at room temperature for 1
After drying for a while, it becomes smooth and shiny (60 degree specular gloss value 8)
9) lijl! A coating film was obtained.

The resulting paint was then applied to a polyurethane sheet to a dry film thickness of 40 μm, and dried at room temperature to obtain a smooth and glossy cured film.

When the resulting coating film was subjected to a bending test in the same manner as in Example 1, cracks that reached the substrate were generated in the coating film. A weather resistance test showed that the gloss retention rate was 95%, indicating excellent weather resistance.

Example 3 100 parts by weight of a silane-modified fluorine-containing copolymer solution prepared according to the recipe of Example 1, with a viscosity of 2000C3 at 25°C
Using a copolymer solution prepared by mixing 20 parts of a linear dimethylpolysiloxane with both ends blocked with methyldimethoxysiloxy groups and 1 part of a 10% xylene solution of dibutyltin dilaurate, a paint having the following composition was prepared. Prepared.

Copolymer solution 60 parts Rutile titanium dioxide 25 parts Cellosolve acetate 10 parts Oxygen
10 parts of the obtained paint was applied to a polyurethane sheet to a dry film thickness of 40 μm, and dried at room temperature to obtain a smooth and glossy cured film.

When the obtained coating film was subjected to a bending test in the same manner as in Example 1, the coating film showed no cracks and exhibited sufficient low-temperature flexibility.

Then, when an accelerated weathering test was conducted for 2000 hours using a Sanshi V in-weather meter, it showed excellent weather resistance with a gloss retention rate of 93%.

[Effects of the Invention] The moisture-curable coating resin composition of the present invention has excellent weather resistance and significantly improved mechanical properties, especially flexibility at low temperatures, and is suitable for use in wood, metal, plastic, slate, and roof tiles. It is especially useful for painting soft plastics.

Claims (1)

[Scope of Claims] 1. (A) A fluorine-containing copolymer containing a hydroxyl group or a hydroxyl group and a carboxyl group in the side chain and an isocyanate-functional silane are added in an amount of isocyanate per mole of hydroxyl group of the fluorine-containing copolymer. (B) 3 parts by weight or less of a curing catalyst was added to 100 parts by weight of a fluorine-containing copolymer having an alkoxysilane group in the side chain obtained by reacting 0.1 to 10 moles of nato-functional silane. A moisture-curable resin composition for paint, characterized by containing a mixture as a main component. 2. (A) A fluorine-containing copolymer containing a hydroxyl group or a hydroxyl group and a carboxyl group in the side chain and an isocyanate-functional silane, and 0 isocyanate-functional silane per mole of hydroxyl group of the fluorine-containing copolymer. (B) 3 parts by weight or less of a curing catalyst and (C) a silanol group or an alkoxysilane group per 100 parts by weight of a fluorine-containing copolymer having an alkoxysilane group in the side chain obtained by reacting at a ratio of 1 to 10 moles. 1. A moisture-curable resin composition for a coating material, characterized in that the main component thereof is a mixture containing 100 parts by weight or less of a polyorganosiloxane having at least two group-bonded silicon atoms per molecule.