JPH0532434B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to coating compositions containing novel cellulose graft polymers having radically polymerizable unsaturated groups. Conventionally, coating compositions commonly used as lacquers have been produced by adding natural or synthetic resins, plasticizers, solvents, etc. to cellulose derivatives, and further mixing and dispersing pigments, etc. A coating film of a coating composition containing a cellulose derivative generally has excellent gasoline resistance, abrasiveness, blocking resistance, and high hardness. However, since the cellulose derivatives used in these materials and natural or synthetic resins have essentially different structures, their compatibility is often insufficient, and their use as coating compositions is severely restricted. In addition, because cellulose derivatives have relatively rigid molecular structures, they are often used in coating compositions in combination with plasticizers such as phthalate esters, and the plasticizers are lost from the coating film over time. This impairs the flexibility of the paint film, making it more likely that paint film defects such as cracks and yoking will occur. In order to solve such problems,
No. 48032 discloses that a polymerizable monomer is graft-polymerized using cellulose acetate butyrate or nitrocellulose, which has a copolymerizable unsaturated group or a functional group consisting of a carbon-hydrogen bond from which hydrogen can be extracted by a radical. It discloses improved compatibility in coating compositions. However, hydrogen can be extracted by unsaturated bonds or radicals introduced into this cellulose derivative. Functional groups consisting of carbon-hydrogen bonds exist in positions relatively close to the cellulose skeleton, and bulky butyryl groups may be present near these functional groups, so they do not necessarily serve as effective grafting points. In order to obtain a graft polymer with sufficiently improved compatibility, it is difficult to obtain a graft polymer with sufficient probability. In order to solve these problems, the present inventors have conducted extensive studies and found that a graft polymer obtained by ring-opening reaction of a cyclic ester in the presence of a cellulose derivative has a radically polymerizable unsaturated group introduced into it. The present invention was completed based on the discovery that the copolymer was sufficiently copolymerized with the radically polymerizable monomer and that the compatibility of this copolymer was significantly improved compared to the cellulose derivative used. That is, the present invention provides a coating characterized by containing a cellulose graft polymer in which a radically polymerizable unsaturated group is introduced into a graft polymer obtained by ring-opening reaction of a cyclic ester in the presence of a cellulose derivative having a hydroxyl group. A composition is provided. The cellulose derivative used in the present invention may be any cellulose derivative having a hydroxyl group in the molecule, such as cellulose acetate, cellulose acetate propionate, cellulose acetate butyrate, cellulose acetate phthalate, cellulose sulfate, cellulose nitrate, etc. or cellulose ethers such as ethyl cellulose and benzyl cellulose. Among these cellulose derivatives, cellulose acetate, cellulose acetate butyrate, cellulose acetate propionate, etc., which are industrially available, easy to handle, and have excellent weather resistance, are preferred. Note that these cellulose derivatives can be used alone or in combination of two or more. The cyclic ester used in the present invention may be one that can be polymerized by a ring-opening reaction using a known method, such as propiolactone, β-butyrolactone, α-α-bischloromethylpropiolactone, α, α-dimethyl-β-propiolactone, δ-valerolactone, β-ethyl-δ-valerolactone, 3,4,5-trimethoxy-δ-valerolactone, 1,4-dioxan-2-one,
Glycolide, trimethylene carbonate, neopentyl carbonate, ethylene oxalate, propylene oxalate, α-methyl-ε-caprolactone, β-methyl-ε-caprolactone, γ
-Methyl-epsilon-caprolactone, epsilon-caprolactone, 4-methyl-7-isopropyl-epsilon-caprolactone, 3,3,5-trimethyl-epsilon-caprolactone, cis-disalicilide, trisalicilide and the like. Among these cyclic esters, it is advantageous to use ε-caprolactone, which is industrially easily available, easy to handle, and has good compatibility with cellulose esters such as cellulose acetate butyrate, cellulose acetate propionate, and cellulose acetate. be. In the present invention, a graft polymer obtained by ring-opening reaction of a cyclic ester in the presence of a cellulose derivative having a hydroxyl group can be obtained by the following method. That is, in the presence of at least one of the above cellulose derivatives, a catalyst used for the ring-opening reaction of a cyclic ester, such as an organic acid, an inorganic acid,
Catalysts such as organic tin compounds, organic acid tin salts, alkali metals, organic compounds of alkali metals, alkylaluminiums, organic compounds of titanium, halides such as tin chloride (the catalysts used in the ring-opening reaction of cyclic esters are , written by Takeo Saegusa "Lecture on polymerization reaction theory 7. Ring-opening polymerization ()" P104-P128
(published by Kagaku Dojin Co., Ltd. in 1973). )
The method of reaction is generally carried out at a temperature of 120 to 230°C for about 0.1 to 96 hours, adding an organic solvent such as xylene as necessary.
197333 (Japanese Unexamined Patent Publication No. 59-86621). The graft polymer has a graft chain consisting of a cyclic lactone with a primary hydroxyl group at the end, and since this graft chain is relatively flexible, the graft polymer has the rigidity that is a feature of cellulose derivatives. It has both flexibility and flexibility due to the grafted chains. Moreover, since the graft polymer has a primary hydroxyl group that is more reactive than other alcoholic hydroxyl groups and is located away from the cellulose skeleton, the hydroxyl group is more reactive than the hydroxyl group that is directly bonded to the cellulose skeleton. Other functional groups, such as carboxyl groups,
Easily reacts with acid halides, acid anhydrides, epoxy groups, isocyanate groups, N-alkoxyamide groups, etc. The cellulose graft polymer of the present invention is obtained by introducing a radically polymerizable unsaturated group into the above-mentioned graft polymer, and there is no particular restriction on the method of introducing it, but for example, (1) acrylic acid, methacrylic acid,
Unsaturated carboxylic acids such as crotonic acid or their acid anhydrides and acid halides, maleic anhydride, and citraconic anhydride that contain a carboxyl group or an unsaturated group capable of radical polymerization with an acid anhydride or acid halide in one molecule. The above-mentioned graft polymer is mixed with an organic compound having the following properties without a solvent or in the presence of a solvent, and if necessary, in the presence of acetic anhydride, trifluoroacetic anhydride, etc., without a catalyst or with a known esterification catalyst, such as sulfuric acid. , chloroacetic acid, triethylamine, sodium hydroxide, potassium acetate, zinc chloride, etc., by performing an esterification reaction at a temperature of room temperature to 200°C to add radically polymerizable unsaturated groups to the graft polymer. (2) An organic compound having an epoxy group and a radically polymerizable unsaturated group in one molecule, such as glycidyl acrylate, glycidyl methacrylate, allyl glycidyl ether, and the above graft polymer without a solvent or In the presence of a solvent, if necessary, a base (such as triethylamine, NN-dimethylbenzylamine, sodium hydroxide, etc.),
A method of introducing a radically polymerizable unsaturated group into the graft polymer by carrying out a reaction at a temperature of room temperature to 200°C using a known catalyst of Lewis acids (for example, an ether chain of boron trifluoride, etc.); (3) Polymerizable monomers having one unsaturated group and one hydroxyl group in one molecule (e.g., 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, methacrylic acid polyalkyl glycol monoester, (meth)acrylic acid poly(ε-caprolactone) monoester), diisocyanates (e.g. hexamethylene diisocyanate,
There is a method of introducing a radically polymerizable unsaturated group into the graft polymer by a three-way addition reaction of 2,4-tolylene diisocyanate, xylylene diisocyanate, isophorone diisocyanate, etc.) and the graft polymer. Among methods (3),
Among diisocyanates, those having a difference in reactivity between two isocyanate groups, such as 2,4-tolylene diisocyanate and isophorone diisocyanate, are preferred because they are less likely to form a divinyl compound. A polymerizable monomer having an unsaturated group and one hydroxyl group is reacted in advance with a diisocyanate, such as 2,4-tolylene diisocyanate or isophorone diisocyanate, in which the two isocyanate groups have a difference in reactivity, and 1
A method in which a reactant having one unsaturated group and one isocyanate group in the molecule is reacted with the graft polymer is preferred. These reactions (3) can be carried out without a catalyst or in the presence of a solvent, using a base (e.g., triethylamine, N,N-dimethylbenzylamine, etc.), a metal compound (e.g., dibutyltin dilaurate, stannous chloride, etc.), and known methods. The addition reaction may be carried out using a catalyst at a temperature between room temperature and 130°C.
Incidentally, when performing the above reactions (1), (2), or (3), a small amount of a polymerization inhibitor such as hydroquinone or hydroquinone monomethyl ether may be used as necessary. The cellulose graft polymer of the present invention has excellent coating film properties and improved compatibility by copolymerizing the introduced radically polymerizable unsaturated group with a copolymerizable radically polymerizable monomer (). This makes the cellulose derivative suitable for coated compositions. Here, as the above radically polymerizable monomer (), for example, (a) esters of acrylic acid or methacrylic acid, general formula:

[Formula], R ₁ is hydrogen or methyl group, R ₂ is C _1-20 alkyl group, C _5-6 cycloalkyl group, methoxybutyl group, ethoxybutyl group, phenyl group, benzyl group , allyl group, dicyclobentinyl group, C2 _~8
hydroxyalkyl group, polyethylene glycol group, poly-ε-caprolactone group, etc. (b) Vinyl aromatic compound general formula

[Formula], R ₃ is hydrogen or a methyl group, and X is hydrogen, a methyl group, a halogen, a nitro group, an amino group, -N (alkyl) ₂
These are the basics. (c) Radically polymerizable unsaturated monomers having functional groups: glycidyl methacrylate, glycidyl acrylate, allyl glycidyl ether, acrylic chloride, methacryloyl chloride, methacrylic acid, acrylic acid, maleic anhydride, crotonic acid, itaconic acid, N -methylol acrylamide, N-butoxymethylol acrylamide, etc. (d) Other radically polymerizable unsaturated monomers vinyl acetate, butadiene, chlorobrene, isobrene, acrylonitrile, methacrylonitrile,
Examples include vinyl chloride, ethylene, carboxylic acid vinyl ester, and the like. The copolymer of the cellulose graft polymer and the radically polymerizable monomer () of the present invention can be prepared by using peroxides such as benzoyl peroxide and lauroyl peroxide, α,
Bulk polymerization and solution polymerization are carried out using radical polymerization initiators such as azo compounds such as α′-azobisisobutyronitrile and potassium persulfate, and by adding chain transfer agents such as mercaptans as necessary. , emulsion polymerization, suspension polymerization, etc., generally at a temperature of room temperature to 200°C, preferably 60 to 150°C. Although the ratio of the cellulose graft polymer of the present invention and the radically polymerizable monomer () used in the copolymerization is not particularly limited,
Preferably, the weight ratio of grafted cellulose polymer/radically polymerizable monomer () = 5 to 70/95 to
Copolymerize at a ratio of 30%. In order to use the obtained copolymer containing the cellulose graft polymer as a coating composition, it may be used in the form of powder, solution, or dispersion, and is generally used in the form of acetone, ketones such as methyl ethyl ketone, or methyl cellosol acetate. , cellosolve acetate, esters such as ethyl acetate, butyl acetate, and cyclic ethers such as dioxane and tetrahydrofuran. , aliphatic hydrocarbons such as heptane, octane, and mineral spirits, and alcohols such as ethanol and isopropanol may also be used. The thus obtained coating composition of the present invention may contain additives normally added to coating agents, such as diluents such as thinners, coating drying rate regulators, plasticizers such as phthalate esters, leveling agents, or melamine compounds, polyesters, etc. Appropriate amounts of crosslinking agents such as isocyanates and epoxy compounds, thickeners, dyes, pigments, etc. may be added. The coating composition of the present invention can be applied to the object to be coated, such as metal, wood, etc., by a known method such as brush coating, spray coating, roll coating, curtain flow coating, or dip coating.
It can be applied to paper, ceramics, concrete, glass, mortar, plastics, etc. It is also useful as a binder for paper processing coatings and printing inks. In addition, since the cellulose graft polymer of the present invention has radically polymerizable unsaturated groups and flexible graft chains, it can be used in combination with polyfunctional acrylates, unsaturated polyesters, sensitizers, etc. as a photocurable coating agent. It can also be used as a component of an electron beam curable coating agent together with polyfunctional and monofunctional acrylates. Next, further explanation will be given in synthesis examples and examples. Synthesis Example 1 1 with stirrer, reflux condenser and thermometer
Tetrabutyl titanate in a glass flask
150g of ε-caprolactone containing 200PPm and thoroughly dried cellulose acetate (Daicel Chemical Co., Ltd.)
Co., Ltd.; LL-10) is charged, heated to 120°C, stirred thoroughly under a nitrogen atmosphere, and dissolved. after that
The temperature was raised to 160°C and the reaction was carried out for 16 hours to obtain a pale yellow graft polymer. Synthesis Example 2 The reaction was carried out in the same manner as in Synthesis Example 1, except that 150 g of cellulose acetate butyrate (manufactured by Eastman Chemical Company; CAB-551-0.2) was used in place of cellulose acetate in Synthesis Example 1, and a pale yellow graft was obtained. A polymer was obtained. Example 1 A glass flask equipped with a stirrer, a reflux condenser, a thermometer and a dropping funnel contained 30 g of the graft polymer obtained in Synthesis Example 1 and 0.5% of N,N-dimethylbenzylamine. Add 300g of methyl ethyl ketone, heat to 78℃, and dissolve. This stuff contains p-tert-butylcatechol 0.2
Add 5g of glycidyl methacrylate containing 78%
The reaction is carried out at ℃ for 3 hours. Next, add 10g of ethyl acrylate, 50g of methyl methacrylate, and n-butyl methacrylate to this.
A radically polymerizable monomer solution containing 50 g of styrene, 20 g of styrene, and 10 g of acrylic acid, and a solution of 0.8 g of benzoyl peroxide and 19 g of toluene were each separately added dropwise over 3 hours under a nitrogen atmosphere. The reaction is further continued at 78-80°C for 5 hours. A coating composition containing a cellulose graft polymer with a solids content of 35.7% and a viscosity of 3260 CPS was thus obtained. When the coating composition was applied to a mild steel plate using a No. 40 bar coater and dried, a transparent and glossy coating film was obtained. Table 1 shows the results of evaluating the performance of this coating film. Example 2 18 g of the graft polymer obtained in Synthesis Example 2 and methyl ethyl ketone were placed in two glass flasks equipped with a stirrer, a reflux condenser, a thermometer, and a dropping funnel.
200 g, 3.6 g of maleic anhydride, and 1.0 g of pyridine were charged, and heated to 80°C while stirring. When a homogeneous solution is obtained, the reaction is carried out at 80° C. for 5 hours, and then a mixture of 28.8 g of styrene, 60 g of methyl methacrylate, 12 g of acrylic acid and 1.0 g of benzoyl peroxide is added dropwise under a nitrogen atmosphere over a period of 1 hour. Thereafter, polymerization was carried out at 80°C for 2 hours. After that, 68.4 g of methyl methacrylate, 60 g of ethyl acrylate, 54 g of butyl acrylate, 18 g of 2-hydroxyethyl methacrylate, 15.6 g of acrylic acid, and benzoyl peroxide.
1.2 g of a mixture of 140 g of methyl ethyl ketone
Drip over time. Thereafter, a polymerization reaction is carried out at 80°C for 4 hours. 16.8 g of triethylamine and butyl cellosolve were added to the pale yellow polymer solution thus obtained.
After adding 23.4g and 277.6g of water and stirring thoroughly,
A coating composition was obtained containing a cellulose graft polymer which was a milky white water dispersion with a solids content of 33.8%, a viscosity of 5430 CPS, and a pH of 7.2. When the coating composition was applied to a mild steel plate using a No. 40 bar coater and dried, a transparent and glossy coating film was obtained. Table 1 shows the results of evaluating the performance of this coating film. Example 3 100g of coating composition obtained in Example 2
Water-soluble epoxy compound, glycerol polyglycidyl ether (manufactured by Nagase Sangyo Co., Ltd.; Denacol EX)
-313) was added, stirred thoroughly, and applied to a mild steel plate using a No. 40 bar coater. When dried at 100°C for 30 minutes, a transparent and glossy coating film was obtained. Table 1 shows the results of evaluating the performance of this coating film. Example 4 174 g of 2,4-tolylene diisocyanate is charged into a glass flask equipped with a stirrer, a reflux condenser, a thermometer and a dropping funnel and maintained at 50°C.
130 g of methacrylic acid 2-hydroxy ether containing 0.1% of hydroquinone was added dropwise over 4 hours. Thereafter, the mixture was kept at 50°C and stirred for 5 hours, then sealed and left overnight. In this way, a white wax-like isocyanate group-containing methacrylic ester is obtained. The graft polymer obtained in Synthesis Example 2 (hydroxyl value: 43.2 (KOH
mg/g)), 23.1 g of the above white wax-like isocyanate group-containing methacrylic acid ester, and 200 g of methyl ethyl ketone were charged, and the temperature was raised to 60° C. with stirring. Thereafter, a reaction was carried out at 60° C. for 6 hours to obtain a grafted cellulose polymer solution with a solid content of 38.1%. 52.5g of this grafted cellulose polymer solution,
Oligoester acrylate (Toagosei Chemical Industry Co., Ltd.)
Co., Ltd.; Aronix M-6300) 25g, trimethylolpropane triacrylate 10g, 2-ethylhexyl acrylate 30g, 2-hydroxyethyl methacrylate 10g, benzophenone 2.5g and dimethylaminoethanol 2.5g were mixed with stirring to form a coating composition. I got something. This was applied to a mild steel plate using a No. 30 bar coater, set at 50℃ for 10 minutes, and then horizontally placed 9cm vertically below a 2kW high-pressure mercury lamp (manufactured by Iwasaki Electric Co., Ltd.) with a length of 25cm. 3m/
It is cured by placing it on a belt moving at a speed of min.
A coating film was obtained. Table 1 shows the results of evaluating the performance of this coating film. As shown in Table 1, the coating films obtained in Examples 1 to 4 are all coating films with excellent practicality, and it is clear that the coating composition of the present invention is extremely useful. It is.

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Claims (1)

[Claims] 1. A coating composition comprising a cellulose graft polymer obtained by introducing a radical and polymerizable unsaturated group into a graft polymer obtained by ring-opening a cyclic ester in the presence of a cellulose derivative having a hydroxyl group. .