JPS61296073A - Composition for coating compound - Google Patents

Abstract

PURPOSE:The titled composition of a fluorine-contained resin system of a solvent-soluble type having improved weather resistance, obtained by reacting a hydroxyl group-containing fluorine-contained polymer with an isocyanate group-containing unsaturated compound in a specific ratio. CONSTITUTION:The aimed composition containing an unsaturated group- containing fluorine-containing polymer is obtained by reacting (A) an isocyanate group-containing unsaturated compound [preferably (meth)acrylic acid residue- containing compound] containing one or more isocyanate groups and one or more additionally polymerizable unsaturated groups with (B) a hydroxyl group- containing fluorine-contained polymer in a ratio of number of isocyanate groups/ number of hydroxyl groups of 0.01-1.0.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a solvent-soluble fluororesin coating composition with excellent weather resistance.

[Prior Art] Conventionally, for the purpose of protecting plastic films or molded products, methods have been known in which the surface is coated with a resin that has better weather resistance than the base material.
Solvent-soluble fluororesin paints, such as those found in Japanese Patent Application Laid-Open No. 107, No. 189-107, and No. 87-518-80, have extremely excellent weather resistance, so they can be used on substrates. It is attracting attention as a material that protects general-purpose plastics from UV rays and other environmental factors, giving them long-term durability.

However, in these publicly known hydroxyl group-containing fluoropolymers, the hydroxyl groups in the molecules are crosslinked with an isocyanate-based or melamine-based curing agent, so in order to cure the coating film, heating at around 80°C for several days at room temperature is required. It takes even a few minutes. Therefore, in line painting of plastic films or molded products, there is a problem in that the film is wound up or stacked before it is completely cured. Of course, it is possible to cure in a short time by heating at a high temperature of 100° C. or higher, but the heat resistance of plastic substrates is often low, so heating to high temperatures is not preferable.

On the other hand, even when a highly heat-resistant base material such as metal is used, curing may be required at a relatively low temperature, and the curing time may also need to be shortened. For example, fluororesin paints that can be cured in a short time at room temperature or at relatively low temperatures are often required for substrates other than plastic substrates.

[Problems to be Solved by the Invention] The present invention introduces an addition-polymerizable double bond into a conventional solvent-soluble hydroxyl group-containing fluoropolymer. The object of the present invention is to provide a coating composition that can be used in combination with curing and that can be cured at low temperatures and in a short time.

[Means for Solving the Problems] The present invention has been made to solve the above-mentioned problems, namely, an isocyanate having at least one isocyanate group and at least 14vi addition-polymerizable unsaturated groups. The group-containing unsaturated compound and the hydroxyl group-containing fluoropolymer have a ratio of number of isocyanate groups/number of hydroxyl groups of about 0.0.
This is a coating composition containing an unsaturated group-containing fluoropolymer obtained by reacting at a ratio of 1 to 1.0.

In the present invention, the isocyanate group-containing unsaturated compound is preferably a compound having an acrylic acid or methacrylic acid residue as an addition polymerizable unsaturated group. Compared to other unsaturated groups (for example, impropenyl groups), these residues are easily polymerized by ultraviolet rays, etc., which will be described later, and the coating cures quickly and at relatively low temperatures.Of course, unsaturated groups containing isocyanate groups The compound is not limited to this, and for example, isopropenyldimethylbenzyl isocyanate and the like can also be used. Examples of isocyanate group-containing unsaturated compounds having residues of acrylic acid or methacrylic acid (hereinafter the term "(meth)acrylic acid" will be used to indicate both, and terms such as "(meth)acrylate" are also used) include, for example. (meth)acrylate having an isocyanate alkyl group, a partial reaction product of a hydroxyl group-containing (meth)acrylate such as hydroxyalkyl (meth)acrylate, and a polyisocyanate compound, a polyol having a (meth)acrylic acid residue and a polyisocyanate compound. There are isocyanate group-terminated urethane prepolymers obtained by reaction. Among these, particularly preferred are (meth)acrylates having an isocyanate alkyl group, followed by the latter two isocyanate group-containing acrylurethanes.

The (meth)acrylate having an isocyanate alkyl group is preferably a (meth)acrylate having a linear, branched, or cyclic isocyanate alkyl group having 2 to 8 carbon atoms (excluding the carbon atoms of the isocyanate group). The isocyanate group is preferably present at the end of this group, ie the isocyanate alkyl group is an ω-isocyanate alkyl group. It is particularly preferred that the isocyanate alkyl group has 2 to 4 carbon atoms, excluding the carbon atoms of the isocyanate group. Specific isocyanate alkyl (meth)acrylates include, for example, 2-
Examples include isocyanate ethyl methacrylate, 2-isocyanate ethyl acrylate, 4-isocyanate butyl methacrylate, and 4-isocyanate butyl acrylate.

Isocyanate group-containing acrylic urethanes include hydroxyalkyl (meth)acrylates, partial esters of polyhydric alcohols and (meth)acrylic acid (esters having at least one hydroxyl group), other hydroxyl group-containing (meth)acrylates, and polyisocyanates. There are compounds or compounds which are reactants with isocyanate group-terminated urethane prepolymers and which have at least one isocyanate group. For example, the reaction product of 1 mole of hydroxyalkyl (meth)acrylate and 1 mole of diisocyanate compound, the reaction product of 1 to 2 moles of hydroxyalkyl (meth)acrylate and 1 mole of triisocyanate compound, di(meth)acrylate of triol. 1
reaction product of 1 mole of diisocyanate compound,
reaction product of 1 mole of mono(meth)acrylate of a triol with more than 1 mole of a diisocyanate compound,
Examples include a reaction product of 1 mol of hydroxyalkyl (meth)acrylate, 1 mol of isocyanate group-terminated prepolymer obtained by reacting a diol with a diisocyanate compound, and the like. A preferred isocyanate group-containing acrylic urethane is a reaction product of a hydroxyalkyl (meth)acrylate or a partial ester of a polyhydric alcohol and (meth)acrylic acid having one hydroxyl group, and a polyisocyanate compound, particularly one or two hydroxyl groups. It is a compound having one isocyanate group.

The above-mentioned polyisocyanate compound may be a yellowing polyisocyanate or a modified product thereof, but a non-yellowing polyisocyanate or a modified product thereof is particularly preferred from the viewpoint of weather resistance. Non-yellowing polyisocyanates include aliphatic polyisocyanates, alicyclic polycincyanates, and aromatic polyisocyanates in which the isocyanate group is not directly bonded to an aromatic nucleus. Examples of modified products include prepolymer-type modified products (for example, trimethylolpropane-modified products), trimerized products (also known as incyanurate products), carbodiimide-modified products, urea-modified products, and dimerized products. Examples of non-yellowing polyisocyanates include hexamethylene diisocyanate, trimethylhexamethylene diisocyanate, lysine diisocyanate, inphorone diisocyanate, methylene bis(cyclohexyl isocyanate), and xylylene diisocyanate. Examples of the polyhydric alcohol include ethylene glycol, polyethylene glycol, propylene glycol, polypropylene glycol, 1,4-butanediol, neopentyl glycol, hexylene glycol, trimethylolpropane, glycerin, and pentaerythritol. In particular, polyhydric alcohols having 8 or less carbon atoms are preferred. Examples of hydroxyalkyl (meth)acrylates include 2-hydroxyethyl methacrylate, 2-hydroxyethyl acrylate, 2-hydroxypropyl methacrylate, and 2-hydroxypropyl acrylate.

As the hydroxyl group-containing fluorine-containing polymer, a monomer that essentially includes a polyfluoroolefin and a hydroxyl group-containing vinyl ether, and preferably a vinyl ether that does not further contain a hydroxyl group, is used, and these two or three types are used as main components and copolymerized. A polymer obtained by These 2-3
Each of the seed monomers may consist of two or more monomers. Examples of polyfluoroolefins include those having 2 or more carbon atoms, such as tetrafluoroethylene, chlorotrifluoroethylene, vinylidene fluoride, and hexafluoropropylene.
The polyfluoroolefins of No. 3 are suitable, with tetrafluoroethylene and chlorotrifluoroethylene being particularly preferred. As the hydroxyl group-containing vinyl ether, hydroxyalkyl vinyl ethers are suitable, especially those having 3 to 3 carbon atoms.
Vinyl ethers having 8 hydroxyalkyl groups are preferred. Specific examples include hydroxypropyl vinyl ether, hydroxybutyl vinyl ether, hydroxyisopropyl vinyl ether, and hydroxy-2-methylbutyl vinyl ether. A particularly preferred hydroxyl group-containing vinyl ether is 4-hydroxybutyl vinyl ether.

The hydroxyl group-containing fluorine-containing polymer can be obtained from the above two monomers, the polyfluoroolefin and the hydroxyl group-containing vinyl ether, but is preferably further copolymerized with another copolymerizable monomer. The copolymerizable monomer is particularly preferably vinyl ether having no hydroxyl group, but is not limited thereto. Vinyl ethers without hydroxyl groups may also be vinyl ethers with fluorine atoms. Preferred examples of these vinyl ethers include linear monobranched or cyclic vinyl ethers having an alkyl group that may have a fluorine atom, such as alkyl vinyl ethers, cycloalkyl vinyl ethers, and poly(or mono)fluoroalkyl vinyl ethers. The compound is a vinyl ether having a linear or branched alkyl group having 1 to 101 carbon atoms, especially a cycloalkyl vinyl ether having a linear or branched alkyl group having 2 to 6 carbon atoms, a cycloalkyl vinyl ether which may have a side chain having 6 to 10 carbon atoms, and 2 or more fluorine atoms. It is a polyfluoroalkyl vinyl ether having 3 to 6 carbon atoms. Specifically, for example, ethyl vinyl ether, propyl vinyl ether, butyl vinyl ether, hexyl vinyl ether, cyclohexyl vinyl ether, 2,2
, 3,3-tetrafluoropropyl vinyl ether and the like. Further, polyfunctional vinyl ethers such as divinyl ether can be used together with or in place of these vinyl ethers.

Particularly preferred vinyl ethers having no hydroxyl group are ethyl vinyl ether, butyl vinyl ether, and cyclohexyl vinyl ether.

In addition, copolymerizable monomers other than vinyl ether can also be used in place of or together with these vinyl ethers that do not have a hydroxyl group. For example, alkyl methacrylates, alkyl acrylates, olefins, and other copolymerizable polymers can be used. but,
The use of copolymerizable monomers other than vinyl ether often reduces the solubility and other properties of the hydroxyl group-containing fluorine-containing copolymer, and therefore, even if used, it should be used in small amounts (for example, less than about 5 mol% of Kaneko Tsuma). It is preferable that there is
Generally not used substantially.

Polyfluoroolefin/Hydroxy group-containing vinyl ether/
The copolymerization ratio of the copolymerizable upper layer is approximately 30% by mole.
-70/1-4570-68 is preferred, particularly about 40-60/3-4015-57, and most preferably about 40-6075-30/10-55. The polymerization method is preferably carried out by the method described in the above-mentioned publication.

The resulting hydroxyl group-containing fluoropolymer is usually solvent soluble. The intrinsic viscosity of this polymer, measured in tetrahydrocran at 30 DEG C., is preferably in the range of about 0.05 to 2.0 dl/g.

The reaction ratio between the isocyanate group-containing unsaturated compound and the hydroxyl group-containing fluoropolymer is the number of isocyanate groups/
It is necessary that the ratio expressed as the ratio of the number of hydroxyl groups is about 0.01 to 1.0.

If the number of isocyanate groups is less than this ratio, it will be difficult to obtain an unsaturated group-containing fluoropolymer with an insufficient number of unsaturated groups, and on the other hand, if it is more than this ratio, it will be difficult to obtain an unsaturated group-containing fluoropolymer. If the isocyanate group-containing unsaturated compound remains for reaction and its amount increases, there is a risk that problems such as deterioration of the physical properties of the coating film may occur. A more preferred ratio is about 0.1 to 1.0, particularly about 0.3 to 1.0. In the reaction, the urethanization catalyst described below can be used, and it is particularly preferable to use an organic tin compound.

The above-mentioned unsaturated group-containing fluoropolymer in the present invention is used as a coating film-forming component of a coating composition.Since this polymer has an unsaturated group, it can be polymerized and cured with only this compound. Further, this compound can be polymerized and cured together with other compounds having polymerizable unsaturated groups.

When the unsaturated group-containing fluoropolymer has hydroxyl groups (that is, in the case of a compound obtained under conditions where the ratio of the number of isocyanate groups/number of hydroxyl groups is less than 1.0), this hydroxyl group is also cured. It can be involved in the curing of the coating film by reaction with the agent.

That is, as mentioned above, it is also possible to harden with a polyisocyanate or melamine hardening agent. That is, the unsaturated group-containing fluoropolymer can of course be cured by addition polymerization of the unsaturated group, but it can also be cured by the use of a curing agent. For this reason, the coating composition of the present invention has the below-mentioned characteristics not found in conventional coating compositions containing a hydroxyl group-containing fluoropolymer, and also exhibits less curing compared to conventional coating compositions. The use of this agent improves weather resistance and allows for faster curing at lower temperatures.

The coating composition of the present invention can be cured not only by heat, but also by energy rays such as ultraviolet rays, electron beams, and gamma rays.

For example, a photopolymerization initiator and a photosensitizer can be blended to form an ultraviolet curable coating composition. Further, an addition polymerization initiator such as a radical generator can be added to form a thermosetting coating composition. Furthermore, it is also possible to cure with high-energy energy beams such as electron beams without adding a photopolymerization initiator or photosensitizer. The coating composition of the present invention is most preferably an ultraviolet curable coating composition containing a photopolymerization initiator or further containing a photopolymerization initiator or the above-mentioned curing agent. The composition can be cured in a short time at room temperature, and can be heated to further increase the curing speed.

The coating composition of the present invention may contain various coating components other than the unsaturated group-containing fluoropolymer. Usually, the coating composition is used in the form of a solution in a solvent. Further, it is also possible to form a dispersed composition using a non-dissolving dispersion medium. Examples of solvents that can be used include aromatic hydrocarbons such as xylene and toluene, esters such as butyl acetate, ketones such as methyl isobutyl ketone, and glycol ethers such as ethyl cellosolve. The above photopolymerization initiators include Ritoeva, acetophenone, benzophenone, benzyl, benzoin, benzoin ether, other carbonyl compounds, sulfur compounds such as thioxanthone, azo compounds such as azobisisobutyronitrile, and benzoyl peroxide. or di-t-butyl peroxide. As the photosensitizer, amines such as triethylamine and triethylenetetramine, ureas, phosphorus compounds, and other compounds can be used as appropriate. As the thermal polymerization initiator, the above-mentioned azo compounds, peroxides, and the like can be used.

As mentioned above, in the present invention, other unsaturated compounds having addition polymerizable unsaturated groups can be used together with the unsaturated group-containing fluoropolymer. Examples of the unsaturated compound include (meth)acrylate, styrene, unsaturated alkyd, (meth)acrylate oligomer, polyester (meth)acrylate, epoxy (meth)acrylate, and polyurethane (meth)acrylate. Particularly preferred are (meth)acrylic acid derivatives, and among these, polyfunctional (meth)acrylates (i.e. two or more (meth)acrylates in one molecule) are particularly preferred.
(meth)acrylates having meth)acrylic acid groups are most preferred; specifically, polyesters of polyhydric alcohols and (meth)acrylic acid, oligomeric polyols such as polyester polyols, and (meth)acrylic acid. Examples include (meth)acrylic acid adducts of polyesters and polyepoxy compounds. The amount of these unsaturated compounds to be used is not particularly limited, but if the amount is too large, the characteristics of the fluororesin paint will be lost, so It is preferable to use less than the same weight, especially about the same weight or less.

When the unsaturated group-containing fluoropolymer has hydroxyl groups, a curing agent capable of crosslinking the hydroxyl groups, such as an isocyanate type or melamine type curing agent, may be blended. As this curing agent, an isocyanate curing agent having two or more isocyanate groups is particularly preferable. As the isocyanate curing agent, the above-mentioned non-yellowing polyisocyanates and modified products thereof are preferred. In addition, homopolymers and copolymers of isocyanate alkyl (meth)acrylates, or alkyl (meth)acrylates and isocyanate alkyl (meth)acrylates are also available.
A copolymer with a copolymerizable monomer such as meth)acrylate can be used as the isocyanate curing agent. Isocyanate curing agent is also called isocyanate)
No. 3 may be temporarily blocked with a blocking agent. When the coating composition is cured by heating or the like, the blocking agent is removed and free isocyanate groups are generated, which act as a curing agent. By using a curing agent having a blocked isocyanate group, a coating composition containing an isocyanate curing agent, which is normally a two-component type, can be made into a one-component coating composition. As for blocking agents,
Examples include phenols, ketoximes, lactams, and bisulfites. Furthermore, when using an isocyanate curing agent, it is preferable to use a urethanization catalyst that promotes the reaction between hydroxyl groups and isocyanate groups.

Examples of this catalyst include tertiary amine catalysts and organometallic compound catalysts, and organotin compound catalysts such as dibutyltin dilaurate are particularly preferred.

The coating composition of the present invention may also contain additives other than the above-mentioned components. For example, pigments, fillers, dispersion stabilizers, leveling agents, viscosity modifiers, antigelation agents, ultraviolet absorbers, light stabilizers, moisture absorbers, and the like can be optionally blended depending on the purpose.

The present invention will be specifically explained below using synthesis examples and examples, but the present invention is not limited to these synthesis examples and examples.

Synthesis Example 1 [Synthesis of hydroxyl group-containing fluoropolymer] According to the method described in JP-A-57-34107, the following
Polymers A-1 and A-2 were produced from the monomer compositions listed in the table. Polymer hydroxyl value (OHV), number average molecular weight (M
n), the intrinsic viscosities determined in tetrahydrofuran at 30° C. are given in Table 1.

Table 1 Synthesis Example 2 [Synthesis of unsaturated group-containing fluoropolymer] 2-Isocyanate nityl methacrylate (hereinafter referred to as IEM) was added to the solutions of the above polymers A-1 and A-2 at 80 to 70°C. The reaction was carried out for 1 to 3 hours. The reaction was investigated using an infrared absorption spectrum, and completion of the reaction was confirmed by the disappearance of the absorption peak of the isocyanate group. Unsaturated group-containing fluoropolymers B-1-B-5 listed in Table 2 were synthesized by varying the amount of IEM used. Table 2 shows the type of the hydroxyl group-containing fluoropolymer used and the amount used in IE expressed as the number of isocyanate groups/number of hydroxyl groups (NCOlo)I).

On the other hand, for comparison, IEM usage (NGOloH
) with o, oot and 2.0 (containing unreacted IEM) were produced. These two are C-
1,C-2 and are also shown in Table 2 below. Each polymer was used in the following Examples and Comparative Examples except for the solvent.

Table 2 Examples 1-5. Comparative Examples 1 and 2 Using the unsaturated group-containing fluoropolymer synthesized in Synthesis Example 2, a coating composition having the following composition was manufactured.

Unsaturated group-containing fluoropolymer 60 parts by weight neopentyglycol diacrylate
101/Photopolymerization initiator (benzophenone) 10 Reactive diluent (2-ethylhexyl acrylate) 20 The above coating composition was applied onto an aluminum plate, dried at 40°C for 1 minute, and then heated with a 2 kW high-pressure mercury lamp. Ultraviolet rays were irradiated for 60 seconds at room temperature from a height of 10 cm.

The adhesion, chemical resistance, weather resistance, and dryness to touch of the resulting coating film were measured by the following methods. The results are shown in Table 3 below.

Adhesion: Edge adhesion test according to JISK5400 Chemical resistance: Xylol rubbing test Judgment: Q, 200 times or more, above: % or more A coating composition having the composition shown in Table 4 below was produced using an unsaturated group-containing fluoropolymer. After coating this on an aluminum plate, it was irradiated with ultraviolet rays for 20 seconds under the same conditions as in Examples 1 to 5, and then heated at 150°C for 30 minutes to harden the coating film. Table 4 shows the physical properties of the resulting coating film.

Table 4: Trimerized modified hexamethylene diisocyanate blocked with ε-caprolactam [Effects of the invention] As shown in the examples, the present invention provides a solvent-soluble fluororesin paint that has the effect of UV irradiation. Plastic films, which require curing at low temperatures, allow
This has the effect of expanding the scope of application to line painting coatings on molded products.

Furthermore, by leaving hydroxyl groups in the unsaturated group-containing fluorine-containing polymer, it is possible to use a combination of room temperature or heat curing using ordinary isocyanate-based or melamine-based curing agents, and photo-curing.

Claims (5)

[Claims] (1) The isocyanate group-containing unsaturated compound having at least one isocyanate group and at least one addition-polymerizable unsaturated group and the hydroxyl group-containing fluoropolymer have a ratio of the number of isocyanate groups/the number of hydroxyl groups of approximately 0.01-1.
A coating composition containing an unsaturated group-containing fluoropolymer obtained by reacting at a ratio of 0. (2) The composition according to claim 1, wherein the isocyanate group-containing unsaturated compound is a compound having a residue of methacrylic acid or acrylic acid. (3) The composition according to claim 2, wherein the isocyanate group-containing unsaturated compound is a methacrylate or acrylate having an isocyanate alkyl group. (4) The hydroxyl group-containing fluoropolymer contains polyfluoroolefins (a), hydroxyl group-containing vinyl ethers (b), and vinyl ethers (c) having no hydroxyl groups (a) to (c).
) in tetrahydrofuran in a proportion of about 40 to 60 mol% of (a), about 3 to 40 mol% of (b), and about 5 to 57 mol% of (c), based on the total amount of 30℃
2. The composition according to claim 1, wherein the composition is a hydroxyl group-containing fluoropolymer having an intrinsic viscosity of about 0.05 to 2.0 dl/g. (5) The composition according to claim 1, wherein the coating composition is a photocurable coating composition containing a photopolymerization initiator.