JP2709481B2 - Method for producing non-aqueous dispersion - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial application field) The present invention is used for steel structures, ships, bridges, general building parts, vehicles, etc., and has long-term weather resistance, high durability, corrosion resistance, and chemical resistance. The present invention relates to a method for producing an excellent, transparent, glossy, low-pollution dispersion for coatings, that is, a non-aqueous dispersion.

(Conventional technology and problems to be solved) Conventionally, non-aqueous dispersion-type paints have features such as higher solid content and lower pollution compared to ordinary organic solvent-soluble paints. Therefore, it is widely used for coating various kinds of objects to be coated.

By the way, conventional non-aqueous dispersions have used acrylic resins, alkyd resins, polyester resins and the like as dispersion stabilizers, but in recent years, from the viewpoint of resource saving and energy saving, a long coating film life, that is, long-term weather resistance There has been a strong demand for the development of a good non-aqueous dispersion type paint, and the dispersion stabilizer resin has not been able to sufficiently meet these demands.

On the other hand, as a paint having good long-term weather resistance, JP-A-57-34107
Organic solvent-soluble coatings using resins represented by the fluorine-containing copolymers described in Japanese Patent Laid-Open Publication No. H07-214, have recently been receiving attention, and recently such types of fluorine-containing copolymers have been used as dispersion stabilizers. Also, non-aqueous dispersions for coatings obtained by graft polymerization of ethylenically unsaturated monomers have been developed.

However, in the non-aqueous dispersion for paint, unless the reaction conditions are carefully set, the acrylic monomer as a particle component does not efficiently graft polymerize to the fluorine-containing copolymer as a dispersion stabilizer, and as a result, The transparency of the resulting coating film is poor, and the pigment dispersibility is poor compared to a conventional non-aqueous dispersion using an acrylic resin or the like as a dispersion stabilizer, and as a result, an enamel type non-aqueous liquid using the non-aqueous dispersion is used. There was a problem that the glossiness of the dispersion type paint film was inferior.

In view of such a current situation, the present inventors can obtain a coating film excellent in transparency, gloss and the like while utilizing the good long-term weather resistance and the like of the fluorocopolymer by a simple production means. As a result of intensive studies to develop a method for producing a non-aqueous dispersion for paints, the present invention has been achieved.

(Means for Solving the Problems) That is, the present invention relates to a fluorinated copolymer (B) that is soluble in an organic solvent and has a functional group in an organic solvent (A), and that the organic solvent is difficult to use. A method for producing a non-aqueous dispersion in which an acrylic copolymer (C) having a functional group which is soluble and has a reactivity with the functional group of the copolymer (B) is reacted, and the organic solvent (A) A functional group which is soluble in the organic solvent and has a functional group, and a functional group which is hardly soluble in the organic solvent and has reactivity with the functional group of the copolymer (D) And a method for producing a non-aqueous dispersion by reacting with a fluorine-containing copolymer (E) having

 Hereinafter, the present invention will be described in detail.

As the organic solvent (A) used in the present invention, an organic solvent used in ordinary non-aqueous dispersion paints can be used without any particular limitation.
Naphtha, mineral spirits, solvent kerosene, aromatic naphtha, solvent naphtha and the like, relatively low solubility aliphatic or aromatic hydrocarbons; n-butane, n-hexane,
Representative examples include aliphatic hydrocarbons such as n-heptane, n-octane, isononane, n-decane, and n-dodecane; and alicyclic hydrocarbons such as cyclohexane and cycloheptane. ,toluene,
Aromatic hydrocarbons such as xylene; esters such as ethyl acetate and butyl acetate; ketones such as methyl isobutyl ketone, cyclohexanone, and isophorone may be used in combination.

Specific examples of the fluorine-containing copolymers (B) and (E) having a functional group used in the present invention are described in JP-A-57-3410.
7, JP-A-59-102961, JP-A-59-102962, JP-A-59-1
89108, JP-A-60-67518, JP-A-61-57609, JP-A-62
-7767; fluorinated copolymers described in JP-B-61-49323 and the like. That is, the copolymer is a fluoroolefin, a vinyl ether having a functional group,
A functional group-free vinyl ether (which may be a fluorine-containing vinyl ether) and / or a vinyl carboxylate are used as constituents, and the components are 40 to 60 mol%, 0.5 to 25 mol%, 5 to 60 mol% and / or 5 mol%, respectively. 6060 mol%.

If the fluoroolefin content is too low, the weather resistance usually decreases, while if it is too high, the production is difficult.

The functional group contained in the fluorinated copolymer is usually provided with a functional group such as a hydroxyl group, a glycidyl group or an amino group by copolymerizing a vinyl ether having the functional group, or JP-B-61-49323. As described in the gazette, a carboxyl group is supplied by reacting a copolymer of vinyl ether having a hydroxyl group with a dibasic acid anhydride. In the present invention, however, the present invention is not limited to these, and instead of or in combination with the functional group-containing vinyl ether having the functional component of the fluorinated copolymer, the total amount of the vinyl ether and the vinyl ether is 25. It can be supplied by copolymerizing an ethylenically unsaturated monomer containing a functional group such as a hydroxyl group, a carboxyl group, a glycidyl group, an amino group, or a sulfonic acid group within a range not exceeding mol%. .

In the present invention, it is preferable to use perhaloolefin, particularly chlorotrifluoroethylene or tetrafluoroethylene, as a fluoroolefin as a raw material of the fluorinated copolymer. Further, as the vinyl ether containing no functional group, cyclohexyl vinyl ether and a vinyl ether having a linear or branched alkyl group having 2 to 8 carbon atoms are preferable, and as the carboxylic acid vinyl ester, cyclohexane carboxylic acid vinyl ester, vinyl benzoate esters, esters of aliphatic carboxylic acids of p-tert-butylbenzoic acid vinyl ester or C ₁ -C ₁₀ are preferred.

In the present invention, the fluorine-containing copolymer as described above is a polymerizable initiator such as a water-soluble initiator or an oil-soluble initiator or an ionizable polymer in the presence or absence of a polymerization medium in a predetermined ratio of a monomer mixture. It is produced by allowing a polymerization initiation source such as radiation to act to cause a copolymerization reaction.

Examples of the fluorinated copolymer include Lumiflon LF100, Lumiflon LF200, Lumiflon LF210, Lumiflon LF300, Lumiflon LF400 manufactured by Asahi Glass, and fluororesin K-700, K-710 manufactured by Dainippon Ink and Chemicals, and these are one type. Alternatively, two or more kinds can be used in combination.

The fluorinated copolymer (B) must be soluble in the organic solvent (A) in order to have a function as a dispersion stabilizer of the dispersion. The organic solvent (A) can be prepared by dissolving the polymer (B) selectively or by adjusting the component ratio or the component type within the above range as the fluorine-containing copolymer (B). Use a copolymer that dissolves.

On the other hand, since the fluorinated copolymer (E) becomes a particle component of the dispersion, it needs to be sparingly soluble in the organic solvent (A),
Therefore, an organic solvent (A) that does not dissolve the fluorinated copolymer (E) is selectively used, or the fluorinated copolymer (E) contains the above components in the above proportion within the above range. By using a copolymer that does not dissolve in the organic solvent (A) by adjusting the above.

As the acrylic copolymers (C) and (D) having a functional group used in the present invention, an ethylenically unsaturated monomer having a functional group having reactivity with the functional group of the fluorinated copolymer may be used. Is a copolymer obtained by subjecting an ethylenically unsaturated monomer mixture to radical polymerization by ordinary means.

As the ethylenically unsaturated monomer, specific examples of a monomer having a functional group include acrylic acid, methacrylic acid, maleic acid, fumaric acid, crotonic acid, itaconic acid, maleic anhydride, and 2-hydroxyethyl acrylate. 2-hydroxyethyl methacrylate, 2-hydroxypropyl acrylate, 2-hydroxypropyl methacrylate, glycidyl acrylate, glycidyl methacrylate, methacrylic acid
Representative examples include tert-butylaminoethyl, 2-isocyanatoethyl methacrylate, N-methylolacrylamide, and N-methylolmethacrylamide, but are not limited thereto, and are not limited thereto. Any ethylenically unsaturated monomer having a functional group having reactivity with the functional group can be used without particular limitation.

Specific examples of the monomer having no functional group include methyl acrylate, ethyl acrylate, n-propyl acrylate,
Acrylics such as isopropyl acrylate, n-butyl acrylate, isobutyl acrylate, tert-butyl acrylate, 2-ethylhexyl acrylate, lauryl acrylate, tridecyl acrylate, stearyl acrylate, cyclohexyl acrylate, and dimethylaminoethyl acrylate Acid esters, methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, tert-butyl methacrylate, methacrylic acid-2
Methacrylates such as ethylhexyl, lauryl methacrylate, tridecyl methacrylate, stearyl methacrylate, stearyl methacrylate, cyclohexyl methacrylate, dimethylaminoethyl methacrylate, diethylaminoethyl methacrylate, styrene or vinyl toluene, α-methylstyrene, chloro Representative examples include substituted styrenes such as styrene, acrylonitrile, methacrylonitrile, vinyl chloride, vinyl formate, vinyl propionate, vinyl stearate, dialkyl maleate, divinylbenzene, acrylamide, methacrylamide, and the like.

In addition, the acrylic copolymers (C) and (D) contain the monomer having the functional group as a constituent component in an amount of 0.01 to 25 mol%, preferably 0.1 to 10 mol%, based on all ethylenically unsaturated monomers. %. Within the above range, a stable reaction dispersion with the fluorinated copolymer can be obtained.

The polymerization of the unsaturated monomer is performed using a radical polymerization initiator. Examples of usable polymerization initiators include peroxide radical initiators such as benzoyl peroxide and ditert-butyl peroxide, and azo radical initiators such as azobisisobutyronitrile and azobisvaleronitrile. Initiators may be used. Further, the polymerization reaction can be performed under ordinary radical polymerization conditions. It is preferably carried out at about 80 to 140 ° C. for 3 to 10 hours.

In addition, the acrylic copolymer (C) must be sparingly soluble in the organic solvent (A) since it becomes a particle component of the dispersion, while the acrylic copolymer (D) is a dispersion stabilizer of the dispersion. Therefore, it must be soluble in the organic solvent (A). Therefore, as in the case of the above-mentioned fluorinated copolymer, the organic solvent of the acrylic copolymer is selectively used by selecting the type of the organic solvent, or by appropriately adjusting the component ratio or the component type of the constituent components of the acrylic copolymer. What is necessary is just to adjust the solubility with respect to. The weight-average molecular weight of the fluorinated copolymer and acrylic copolymer used in the present invention is preferably in the following range from the viewpoint of dispersion stability and coating film performance.

That is, the fluorine-containing copolymer (B) which is a dispersion stabilizer
The acrylic copolymer (D) preferably has a weight average molecular weight of 5,000 to 150,000 from the viewpoint of the dispersion stability of the dispersion and the ease of reaction with one of the copolymers serving as the particle components.

On the other hand, the acrylic copolymer (C) and the fluorinated copolymer (E), which are the particle components, are used to obtain a coating film having properties such as solvent resistance and water resistance, and one copolymer serving as a dispersion stabilizer. Weight average molecular weight 20,000 to 150,000 due to ease of reaction with coalescence
Is preferred.

In the present invention, the reaction between the functional groups of the fluorinated copolymer (B) and the acrylic copolymer (C) or the functional group between the acryl-based copolymer (D) and the functional group of the fluorinated copolymer (E) In the above reaction, the combination of the functional groups is not particularly limited as long as both copolymers are reactively bonded, and a combination of various functional groups can be employed. For example, a carboxyl group and a hydroxyl group, a carboxylic anhydride and a hydroxyl group, an isocyanate group and a hydroxyl group,
Representative examples include a glycidyl group and a hydroxyl group, an N-methylol group and a hydroxyl group, a glycidyl group and a carboxyl group, a glycidyl group and an amino group, and an isocyanate group and an amino group.

In particular, in the present invention, a combination of a hydroxyl group and an isocyanate group that allows a smooth reaction at room temperature in the presence of a catalyst is preferable.

From the viewpoint of dispersion stability, the chemical bonding point formed by the reaction between the functional groups of both copolymers is desirably 0.001 to 1 milliequivalent per gram of the solid content of the dispersion.

 Next, the method for producing the non-aqueous dispersion of the present invention will be described.

In a solution obtained by dissolving a fluorinated copolymer (B) or an acrylic copolymer (D) as a dispersion stabilizer in an organic solvent (A), a minimum amount of an organic solvent other than the organic solvent (A) is separately added. A solution of the acrylic copolymer (C) or the fluorinated copolymer (E) as the particle component dissolved in the above is mixed under stirring.

The reaction of both copolymers is carried out in the presence of a catalyst (eg, in the case of a reaction between an isocyanate group and a hydroxyl group, an organic tin compound, a tertiary amine, etc.) in a temperature range from room temperature to the boiling point of the organic solvent (A) or lower. It is particularly preferable to react at a temperature not lower than the glass transition temperature of the copolymer as the particle component.

The mixing ratio of the copolymers (B) and (D) serving as the dispersion stabilizer and the copolymers (C) and (E) serving as the particle components is from 20/80 to 80/20 from the viewpoint of dispersion stability. Particularly, 30/70 to 70/30 is desirable.

When the long-term weather resistance of the coating film obtained in the present invention is particularly important, a non-aqueous dispersion produced from a combination of the fluorinated copolymer (B) and the acrylic copolymer (C) is desirable. On the other hand, when the pigment dispersibility is particularly important, a non-aqueous dispersion produced from a combination of the acrylic copolymer (D) and the fluorinated copolymer (E) is desirable.

The non-aqueous dispersion thus obtained can be used alone as a clear coating at a binder solid content of about 20 to 60%. If necessary, a crosslinking agent such as a melamine resin or a polyisocyanate compound, an inorganic coloring pigment such as titanium white, cadmium yellow or carbon black, an organic coloring pigment such as a phthalocyanine or azo pigment, calcium carbonate, or talc. And an additive such as a film-forming aid, an ultraviolet absorber, a light stabilizer, and a silane coupling agent. The inorganic pigment and the organic pigment can be used by appropriately determining the necessary amounts thereof.

(Effects of the Invention) As described above, the non-aqueous dispersion obtained by the method of the present invention not only has excellent long-term weather resistance, corrosion resistance, chemical resistance, etc. because it uses a fluorinated copolymer, Rather than polymerizing the ethylenically unsaturated monomer under a dispersion stabilizer as in the method described above, the copolymerized product is reacted and bonded to the dispersion stabilizer, so that the coating film has good transparency and further contains fluorine. It is an epoch-making material that sufficiently satisfies the high solid content and low pollution characteristic of a non-aqueous dispersion while eliminating the disadvantages of the copolymer such as pigment dispersibility and poor gloss of the coating film.

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to Examples. In the examples, "parts" and "%" are shown on a weight basis.

<Preparation of Hydroxyl-Containing Fluorinated Copolymers B and E> Fluorinated copolymers B and E having the properties shown in the lower part of Table 1 were prepared from the monomer mixtures shown in Table 1 by a known method. In addition, the numerical value of the monomer in the table was shown by mol%.

<Isocyanate group-containing acrylic copolymer C-1, C-
2. Preparation of D-1, D-2> After the temperature of the organic solvent described in Table 2 was raised to 92 ° C., the monomer and the polymerization initiator were added dropwise over 3 hours, and further added later in the table. The resulting mixture was reacted at 110 ° C. for 4 hours to prepare solutions of acrylic copolymers C-1, C-2, D-1, and D-2. The numerical values in the table are indicated by “parts”.

Examples 1 to 4 The fluorinated copolymer, acrylic copolymer solution, organic solvent and reaction catalyst shown in Table 3 were mixed under stirring and reacted by heating. The numerical values in the table are indicated by “parts”. The obtained non-aqueous dispersions A to D were tested for dilution stability and transparency of the clear film. The results are shown in the lower part of Table 3. As is clear from the table, both stability and transparency were excellent.

Comparative Examples 1 and 2 40% mineral spirit solution 24 of fluorinated copolymer B
9.8 parts, 2-isocyanatoethyl methacrylate 0.07
And 0.05 parts of dibutyltin dilaurate were reacted at 80 ° C. for 3 hours to obtain an unsaturated double bond-containing fluorine-containing copolymer solution.
After the temperature of the solution was raised to 92 ° C, the monomers and the polymerization initiator shown in Table 4 were added dropwise over 3 hours, and the post-additives in the table were further added. A dispersion was prepared. The numerical values in the table are indicated by “parts”.

The resulting non-aqueous dispersions E and F were tested for dilution stability and transparency of the clear film, and the results are shown in the lower part of Table 4. As is clear from the table, dilution stability and transparency were inferior.

Examples 5 to 8 and Comparative Examples 3 to 6 The components shown in Table 5 were added to the non-aqueous dispersions and the fluorinated copolymers obtained in Examples 1 to 4 and Comparative Examples 1 and 2, and a colored paint was prepared. Prepared.

Examples 5 to 8, Comparative Examples 3 to 5
For mineral spirits and for Comparative Example 6 with xylene for a viscosity of 22 seconds (Ford Cup No. 4/20
° C), spray-coated on a mild steel plate to a dry film thickness of 30 µm, and dried for one week at a temperature of 20 ° C and a relative humidity of 75%.

The coating films thus obtained were subjected to various coating film performance tests, and the results are shown in the lower part of Table 5.

As is clear from Table 5, the non-aqueous dispersion paints of Examples 5 to 8 obtained by the method of the present invention were compared with the non-aqueous dispersion paints of Comparative Examples 3 and 4 obtained by the conventional method. Was excellent in initial gloss and the like, and was also inferior to other performances.

Claims (4)

(57) [Claims] 1. A fluorinated copolymer (B) which is soluble in an organic solvent and has a functional group in an organic solvent (A), and which is hardly soluble in said organic solvent and said copolymer (B) A method for producing a non-aqueous dispersion, which comprises reacting an acrylic copolymer (C) having a functional group having reactivity with the above functional group. 2. The fluorinated copolymer (B) has a weight average molecular weight of 5,000 to 150,000, and the acrylic copolymer (C) has a weight average molecular weight of 20,000 to 150,000. The method for producing the non-aqueous dispersion according to the above. 3. An acrylic copolymer (D) which is soluble in said organic solvent and has a functional group in said organic solvent (A), and said copolymer (D) is hardly soluble in said organic solvent and A method for producing a non-aqueous dispersion, which comprises reacting a fluorine-containing copolymer (E) having a functional group having reactivity with the above functional group. 4. The acrylic copolymer (D) has a weight average molecular weight of 5,000 to 150,000, and the fluorinated copolymer (E) has a weight average molecular weight of 20,000 to 150,000. The method for producing the non-aqueous dispersion according to the above.