JP2001288214A - Method for manufacturing modified polyvinyl alcohol- vinyl acetate copolymer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing a modified polyvinyl alcohol- vinyl acetate copolymer that can be used for forming a coating layer having both hydrophilicity and water resistance, by means of irradiation with energy rays for a short time. SOLUTION: The hydroxyl group contained in a polyvinyl alcohol-vinyl acetate copolymer in which the ratio of the vinyl alcohol unit is 30-50 mol% is addition-reacted with 0.1 to 0.5 equivalent mole of at least one selected from the group consisting of acrylic acid and methacrylic acid.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an energy ray-curable ink binder having both hydrophilicity and water resistance.
The present invention relates to a method for producing a modified polyvinyl alcohol / vinyl acetate copolymer useful as a coating agent.

[0002]

2. Description of the Related Art Polyvinyl alcohol and a polyvinyl alcohol-vinyl acetate copolymer are widely and widely used as a binder or a coating agent having excellent hydrophilicity.

[0003] In general, a coating agent containing a polyvinyl alcohol component has low water resistance. Therefore, a method has been proposed in which a curing agent which reacts with a hydroxyl group is added, and the mixture is heated and dried to crosslink to improve water resistance. (JP-A-10-5
09105).

However, the formation of a cross-linked structure by the above-mentioned cross-linking requires long-time heating and drying, so that not only productivity is low, but also heat resistance which cannot withstand the heating and drying conditions. Not applicable for low material.

[0005]

SUMMARY OF THE INVENTION The present invention relates to a method for producing a modified polyvinyl alcohol / vinyl acetate copolymer which can form a coating layer having both hydrophilicity and water resistance at a relatively low temperature in a short time. It is intended to be provided.

[0006]

SUMMARY OF THE INVENTION The present invention achieves the above-mentioned object, wherein the ratio of vinyl alcohol units is 3 or less.
0 to 50 mol% of the hydroxyl group contained in the polyvinyl alcohol / vinyl acetate copolymer is 0.1 to 0.5
A method for producing a modified polyvinyl alcohol / vinyl acetate copolymer, characterized by adding at least one of acrylic acid and methacrylic acid in an equivalent amount.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described specifically.

The polyvinyl alcohol / vinyl acetate copolymer used in the present invention has a vinyl alcohol unit / (vinyl alcohol unit + vinyl acetate copolymer unit) ratio of 30 to 50 mol%.

The ratio of vinyl alcohol units is 30 mol%
When the amount is less than 50%, the hydrophilicity of the obtained coating layer is insufficient. On the other hand, when the amount exceeds 50% by mole, the solubility of the obtained modified polyvinyl alcohol / vinyl acetate copolymer in the acrylic monomer decreases. It is not desirable.

In the present invention, polyvinyl alcohol
At least one addition (esterification) of acrylic acid or methacrylic acid to the vinyl acetate copolymer is carried out using an organic compound such as toluene, cyclohexane, methyl ethyl ketone, or ethyl acetate, which has a boiling point of 60 to 120 ° C. and does not react with the carboxyl group of acrylic acid. Dissolve or disperse in a solvent and stir
It is performed by heating at 0 to 110 ° C.

At least one of acrylic acid and methacrylic acid used in the present invention is used in an amount of 0.1 to 0.5 equivalent times the hydroxyl group contained in the copolymer.

If the ratio of adding at least one of acrylic acid and methacrylic acid is less than 0.1 equivalent times, the water resistance of the obtained coating layer is insufficient, while
If the equivalent amount is exceeded, the curing shrinkage of the coating layer after curing by irradiation with energy rays becomes remarkable, and the smoothness is reduced and the hydrophilicity is also reduced.

In the above addition reaction, a catalyst for promoting the esterification reaction such as p-toluenesulfonic acid and benzenesulfonic acid, and a reaction inhibitor such as hydroquinone and methylhydroquinone are added as required during the above addition reaction. be able to.

The organic solvent used as a medium in the above addition reaction is usually removed after completion of the reaction. In the case of a heterogeneous system, filtration, centrifugation or the like can be removed in some cases, but removal by distillation under reduced pressure at a temperature lower than the reaction temperature becomes possible by selecting a low boiling solvent.

The modified polyvinyl alcohol / vinyl acetate copolymer obtained according to the present invention is usually prepared by dissolving it in an acrylic monomer, methacrylic monomer or the like and preparing it as a solution. It can also be prepared as a solvent solution.

The acrylic monomer used as the above-mentioned solvent is selected in consideration of the hydrophilicity of the obtained coating layer.
Hydroxyl-containing acrylates such as ethylene glycol monoacrylate, propylene glycol monoacrylate, butylene glycol monoacrylate, diethylene glycol monoacrylate, and triethylene glycol monoacrylate, N, N-dimethylaminoethyl acrylate, N, N-dimethylaminoethyl N, N- Nitrogen-containing acrylic monomers such as dimethylaminoethyl acrylate acrylamide, acroylmorpholine, and N-isopropylacrylamide.

The methacrylic monomer used as the solvent may be ethylene glycol monomethacrylate, taking into account the hydrophilicity of the resulting coating layer.
Hydroxyl-containing methacrylates such as propylene glycol monomethacrylate, butylene glycol monomethacrylate, diethylene glycol monomethacrylate, and triethylene glycol monomethacrylate;
N, N-dimethylaminoethyl methacrylate, N,
Nitrogen-containing methacrylic monomers such as N-dimethylaminoethyl N, N-dimethylaminoethyl acrylate methacrylamide and N-isopropyl methacrylamide.

As the acrylic monomer and methacrylic monomer, those described above are used, but some of them can be used in place of another oligomer to which they are added.

Further, if necessary, an adhesive such as a terpene resin, a terpene, a phenol resin, a petroleum resin, a rosin resin, a hydrogenated rosin resin, a rosin ester, or a hydrogenated rosin ester can be used.

Further, if necessary, calcium carbonate,
Talc, alumina, kaolin, titanium oxide, silicon oxide,
Inorganic oxides such as magnesium silicate and calcium silicate, inorganic salts and the like can be used.

The solution of the modified polyvinyl alcohol / vinyl acetate copolymer obtained as described above is applied to a substrate and irradiated with energy rays to form a coating layer having both hydrophilicity and water resistance. Can be formed. The energy rays used are usually ultraviolet rays. When adding a methacrylic monomer,
Further, in the case of an energy beam, it may be used for an electron beam having a high energy level.

[0022]

The present invention will be described more specifically with reference to the following examples.

Example 1 The ratio of vinyl alcohol units (abbreviated as VA ratio) was 3
7.5 mol% of polyvinyl alcohol / vinyl acetate copolymer (Polyvinyl alcohol UM manufactured by Unitika Chemical Co., Ltd.)
R) A 50% toluene solution was prepared using 100 parts by weight, and 5.0 parts by weight of acrylic acid, 0.2 parts by weight of p-toluenesulfonic acid as a catalyst, and 0.05 parts by weight of methylhydroquinone as a reaction inhibitor were prepared. In addition, 10
After heating and stirring for an hour, an acrylic acid-added polyvinyl alcohol / vinyl acetate copolymer was synthesized. As shown in Table 1, the acrylic acid addition ratio was 0.1% of the hydroxyl group of the copolymer.
It was 130 equivalent times.

Subsequently, 200 parts by weight of acroylmorpholine (abbreviated as ACMO) was added as an acrylic monomer, and toluene was removed under a reduced pressure of 0.06 to 0.08 MPa to obtain a solution having a viscosity of 16800 mPa.s. The composition (s) (ACMO solution of acrylic acid-added polyvinyl alcohol / vinyl acetate copolymer) was prepared. The solution viscosity was measured at 20 ° C. using a Brookfield-type rotary viscometer.
Was measured. Irgacure 907 manufactured by Nippon Ciba Geigy Co., Ltd.
One part by weight per part by weight was applied to a polyethylene terephthalate film to a thickness of about 10 μm, and the hydrophilicity and water resistance after ultraviolet irradiation (1000 W) for 30 seconds were evaluated under the following conditions.

(1). Hydrophilicity A straight line was drawn on the coated surface with an aqueous ballpoint pen (0.5 mm core), the sharpness of the straight line was observed, and the hydrophilicity was evaluated according to the following criteria. ○ Clear and smooth straight lines can be drawn. △ Local blurring is observed. X: Remarkable blurring is observed.

(2). Water resistance A water drop was dropped on the coated surface, a change in the area of the water drop was observed, and the water resistance was evaluated according to the following criteria. ○ The area of the water droplet does not spread. After one minute, removing the water droplets restores a smooth coated surface. △ The area of the water droplet does not increase, but if the water droplet is removed after one minute, the smoothness of the coated surface is impaired. × The area of water droplets increases. Even after removing the water drop after one minute,
Notably, the smoothness of the coated surface is impaired. As shown in Table 1, both hydrophilicity and water resistance were excellent.

Example 2 An acrylic acid addition polymer and a composition were prepared in the same manner as in Example 1 except that the VA ratio was changed from 37.5 mol% to 32.5 mol%. The addition ratio of the obtained acrylic acid adduct and the solution viscosity of the composition were as shown in Table 1. Table 1 shows the hydrophilicity and water resistance of the obtained composition.
As shown in Table 2, all were excellent.

Example 3 The VA ratio was increased from 37.5 mol% to 43.8 mol%,
An acrylic acid addition polymer and a composition were prepared in the same manner as in Example 1 except that MO was changed from 200.0 parts by weight to 300.0 parts by weight. The addition ratio of the obtained acrylic acid adduct and the solution viscosity of the composition were as shown in Table 1. The hydrophilicity and water resistance of the obtained compositions were all excellent as shown in Table 1.

Comparative Example 1 An acrylic acid adduct and a composition were prepared in the same manner as in Example 1 except that the VA ratio was changed from 37.5 mol% to 25.4 mol%. The addition ratio of the obtained acrylic acid adduct and the solution viscosity of the composition were as shown in Table 1. The water resistance of the obtained composition was excellent, but the hydrophilicity was poor.

Comparative Example 2 An acrylic acid adduct and a composition were prepared in the same manner as in Example 1 except that acrylic acid was changed from 5.0 parts by weight to 2.0 parts by weight. The addition ratio of the obtained acrylic acid adduct and the solution viscosity of the composition were as shown in Table 1.
Although the obtained composition had excellent hydrophilicity, it had poor water resistance.

COMPARATIVE EXAMPLE 3 The VA ratio was changed from 37.5 mol% to 54.2 mol%, acrylic acid was changed from 5.0 parts by weight to 10.0 parts by weight, and ACMO was added.
Was changed from 200.0 parts by weight to 300.0 parts by weight to prepare an acrylic acid adduct and a composition in the same manner as in Example 1. The addition ratio of the obtained acrylic acid adduct was as shown in Table 1. The composition was insoluble, its solution viscosity could not be measured, and its hydrophilicity and water resistance could not be evaluated.

[0032]

[Table 1]

Example 4 A methacrylic acid addition polymer and a composition were prepared in the same manner as in Example 1, except that 5.0 parts by weight of acrylic acid was replaced by 6.0 parts by weight of methacrylic acid. Table 2 shows the addition ratio of the obtained methacrylic acid adduct and the solution viscosity of the composition.
Was as shown in FIG. The hydrophilicity and water resistance of the obtained composition were evaluated in the same manner as in Example 1 except that the ultraviolet irradiation time was set to 3 minutes. As shown in Table 2, all were excellent.

Comparative Example 4 A methacrylic acid addition polymer and a composition were prepared in the same manner as in Example 4 except that 6.0 parts by weight of methacrylic acid was changed to 40.0 parts by weight. When the hydrophilicity and water resistance of the obtained composition were evaluated in the same manner as in Example 4,
As shown in Table 2, the hydrophilicity was poor.

[0035]

[Table 2]

Examples 5 to 6 Acrylic acid addition polymers and compositions were prepared in the same manner as in Example 1 except that the amounts of acrylic acid used were as shown in Table 3. Table 3 shows the addition ratio of the obtained acrylic acid adduct and the solution viscosity of the composition. When the hydrophilicity and the water resistance of the obtained composition were evaluated in the same manner as in Example 1, as shown in Table 3, all were excellent.

Example 7 The UMR was changed from 100.0 parts by weight to 80.0 parts by weight.
After preparing an acrylic acid adduct in the same manner as in Example 2 except that the acrylic acid was changed from 5.0 parts by weight to 10.0 parts by weight, in addition to 200.0 parts by weight of ACMO, polyvinyl butyral manufactured by Sekisui Chemical Co., Ltd. Resin (PVB) BL
-1 was added in an amount of 20.0 parts by weight and dissolved in the same manner as in Example 1. A composition was prepared and evaluated in the same manner as in Example 1. The results shown in Table 3 were obtained.

Comparative Example 5 An acrylic acid addition polymer and a composition were prepared in the same manner as in Example 1 except that 5.0 parts by weight of acrylic acid was changed to 30.0 parts by weight. When the hydrophilicity and water resistance of the obtained composition were evaluated in the same manner as in Example 1, as shown in Table 3, either one of the hydrophilicity and the water resistance was inferior.

[0039]

[Table 3]

Example 8 As in Example 1, except that after the acrylic acid addition reaction was completed, water produced by the reaction was removed together with the reaction medium (toluene) without adding an acrylic monomer. A solution was prepared by replenishing the toluene removed under reduced pressure, coated on a polyethylene terephthalate film in the same manner as in Example 1, dried with hot air at 80 ° C. for 5 minutes, and then subjected to the hydrophilic treatment of the coating layer in the same manner as in Example 1. And water resistance were evaluated, and good results were obtained.

Comparative Example 6 A composition was prepared in the same manner as in Example 1 except that acrylic acid was not added, and evaluated in the same manner as in Example 1. The coat surface was extremely rough.

[0042]

According to the present invention, it is possible to form a coating layer having both hydrophilicity and water resistance by short-time irradiation with energy rays.
It becomes possible to easily produce a vinyl acetate copolymer. The resulting modified polyvinyl alcohol / vinyl acetate copolymer can be expected as a coating agent for aqueous inkjet paper as an acrylic monomer solution. It can also be used alone or as an aqueous solution or organic solvent solution as an adhesive or coating agent.

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Claims (1)

[Claims] (1) a ratio of a vinyl alcohol unit is 30 to 5;
A modification characterized in that at least one of acrylic acid and methacrylic acid is added in an amount of 0.1 to 0.5 equivalent times the hydroxyl group contained in 0 mol% of the polyvinyl alcohol / vinyl acetate copolymer. A method for producing a polyvinyl alcohol / vinyl acetate copolymer.