JP2000212449A - Stabilized aqueous solution of water-soluble polymer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress the decrease in viscosity for a long period of time at room temperature or under heat by adding acetic acid and thiourea to a water- soluble polymer composition. SOLUTION: To a water-soluble polymer composition, desirably an aqueous solution of an acrylamide-based water-soluble polymer, are added desirably 0.1-1 pt.wt., 0.1-0.3 pt.wt. in particular, based on 100 pts.wt. of the water soluble polymer, of acetic acid and desirably 0.05-5 pts.wt., 0.2-1 pt.wt. in particular, based on 100 pts.wt. of the water soluble polymer, of thiourea. Thus, the water- soluble polymer is prevented from decomposition with time and the aqueous solution thereof does not suffer from decrease in viscosity for a long period of time to be kept stable. Therefore, it is used suitably, for example, for the preparation of black matrices of a cathode ray tube. The water-soluble polymer is desirably dissolved in a concentration of 3-15 wt.% in an aqueous solution. As the water-soluble polymers are exemplified an acrylamide-diacetone acrylamide copolymer, a polyacrylamide and the like.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a thermally stabilized aqueous solution of a water-soluble polymer, and more particularly to an aqueous solution of an acrylamide-based water-soluble polymer suitable as a water-soluble resist material.

[0002]

2. Description of the Related Art Acrylamide-based water-soluble polymers are high-molecular-weight water-soluble polymers and are therefore widely used in the fields of flocculants, papermaking chemicals, petroleum recovery chemicals, and the like. Also in the field of water-soluble resist, it is mainly used in the form of an aqueous solution from the viewpoint of solubility in water, high molecular weight, and the like, and is widely used in pattern formation, particularly in the production of a black matrix of a color CRT. However, an aqueous solution of a water-soluble polymer such as an acrylamide-based water-soluble polymer causes a decrease in viscosity due to decomposition of the polymer over time,
The quality deteriorates. In particular, the tendency is remarkable in a heated state, and in some cases, the desired performance may not be achieved.

[0003] In order to solve such disadvantages, various stabilizers have been proposed. For example, there are metal salts of dithiocarbamic acids (JP-B-49-27660), thiourea and its derivatives (JP-B-49-27662). However, with the recent improvement in the quality of color cathode ray tubes and the rationalization of production, further prevention of deterioration in quality of water-soluble resists has been demanded, and resists with higher stability have been demanded.

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to provide a stabilized aqueous solution of a water-soluble polymer which does not cause a decrease in viscosity even at normal temperature or under heating.

[0005]

The present invention relates to a stabilized aqueous solution of a water-soluble polymer obtained by adding acetic acid and thiourea to an aqueous solution of a water-soluble polymer.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION As the water-soluble polymer used in the present invention, an acrylamide-based water-soluble polymer is preferably used. Examples of the acrylamide-based water-soluble polymer include a polymer or a copolymer of an acrylamide monomer. Examples of the monomer that can be copolymerized with the acrylamide monomer include acrylic acid, methacrylic acid, methacrylamide, diacetone acrylamide, N-methylol acrylamide, and the like. The water-soluble polymer is 3-1 in the aqueous solution.
It is preferable to dissolve it at a concentration of 5% by weight,
More preferably, it is dissolved at a concentration of% by weight.

The amount of acetic acid used as a stabilizer is preferably in the range of 0.1 to 1 part by weight, more preferably 0.05 to 0.5 part by weight, per 100 parts by weight of the water-soluble polymer. , 0.1 to 0.3 parts by weight.
If the amount of acetic acid is too small, the effect of suppressing the change in viscosity becomes small, while if it is too large, it is not economical for the effect. The amount of thiourea used as a stabilizer is preferably in the range of 0.05 to 5 parts by weight, more preferably in the range of 0.1 to 2 parts by weight, and more preferably in the range of 0.1 to 2 parts by weight, based on 100 parts by weight of the water-soluble polymer.
A range of from 1 to 1 part by weight is particularly preferred. If the amount of thiourea is too small, the effect of suppressing the change in viscosity becomes small, while if it is too large, the effect is not only saturated, but also has an adverse effect.

[0008] Acetic acid can be used as neat or in the form of an aqueous solution diluted to an appropriate concentration. Thiourea is
It can be added to a water-soluble polymer aqueous solution in the form of a powder or an aqueous solution. When the viscosity of the aqueous water-soluble polymer solution is high, it is effective to stir and mix using a suitable stirrer after the addition. When acetic acid and thiourea are used in combination, the effect of suppressing a change in viscosity is greater than when only acetic acid is used.

[0009]

EXAMPLES Next, the present invention will be described with reference to examples and comparative examples, but the present invention is not limited to the following examples. Those expressed as "parts" indicate parts by weight.

Comparative Example 1 An aqueous solution A was obtained by mixing and stirring 5 parts of polyacrylamide and 95 parts of ion-exchanged water.

Example 1 An aqueous solution B was obtained by adding 0.01 part of acetic acid and 0.015 part of thiourea to 100 parts of the aqueous solution A of Comparative Example 1 and stirring.

Comparative Example 2 An aqueous solution C was obtained by mixing and stirring 5 parts of an acrylamide-diacetone acrylamide copolymer (copolymerization ratio: 1 mol of diacetone acrylamide per 2 mol of acrylamide) and 95 parts of ion-exchanged water.

Comparative Example 3 To 100 parts of the aqueous solution C of Comparative Example 2, 0.015 part of thiourea was added and stirred to obtain an aqueous solution D.

Example 2 An aqueous solution E was obtained by adding 0.01 parts of acetic acid and 0.015 parts of thiourea to 100 parts of the aqueous solution C of Comparative Example 2 and stirring.

The aqueous solutions A to E obtained above were heated at 23 ° C. and 4 ° C.
Leave in a thermostat at 0 ° C.
The viscosity after one day was measured at 25 ° C. using a B-type viscometer (manufactured by Shibaura System Co., Ltd.). From these measured values, the viscosity retention was determined by the following equation.

[0016]

(Equation 1)

[0017]

[Table 1]

[0018]

The aqueous solution of the water-soluble polymer according to the first aspect can maintain the quality for a long period of time without lowering the viscosity at room temperature and in a heated state, and is suitable for pattern formation, particularly for producing a black matrix of a color cathode ray tube. Used for

Claims (1)

[Claims] 1. A stabilized aqueous solution of a water-soluble polymer obtained by adding acetic acid and thiourea to a water-soluble polymer composition.