JP3277647B2 - Paper impregnating composition and impregnated paper - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an impregnated paper and a paper impregnating composition, and more particularly, to an impregnated paper and a gum-up which are excellent in size, tensile strength, elongation and water resistance and have a good balance. And a paper impregnating composition for obtaining the impregnated paper.

[0002]

2. Description of the Related Art An impregnated paper is one in which a polymer is interposed between pulp or fibers constituting the paper.
It is widely used as abrasive paper, artificial leather paper, gaskets, shoe cores, etc. Such impregnated paper is required to have properties such as size, tensile strength, and water resistance. It is also required to prevent gum up during the production of impregnated paper. Examples of the paper impregnating composition used for the production of such impregnated paper include (meth) acrylate polymer latex, styrene-butadiene polymer latex, acrylonitrile obtained by emulsion polymerization in the presence of a surfactant. -A paper impregnating composition containing a butadiene polymer latex and the like is known. However, these compositions do not provide sufficient sizing of the impregnated paper. Further, in order to improve the size degree, a composition containing a latex obtained by emulsion polymerization using an alkali metal rosinate, an alkali metal oleate, or the like as a surfactant has been proposed. There is a drawback that up-up is likely to occur. Also,
Recently, low molecular weight, high acid value carboxy-modified styrene
A composition comprising a neutralized (meth) acrylate copolymer has been proposed, but the impregnated paper properties such as tensile strength and water resistance are insufficient.

[0003]

SUMMARY OF THE INVENTION An object of the present invention is to provide an impregnated paper excellent in sizing degree, tensile strength, elongation and water resistance and well-balanced, and a paper for obtaining the impregnated paper without generating gum-up. It is to provide a composition for impregnation. The present inventors have conducted intensive studies to achieve this object, and as a result, using an aqueous polymer dispersion obtained by emulsion polymerization of a monomer mixture in the presence of a neutralized product of an alkali-soluble polymer. As a result, it was found that an impregnated paper excellent in size, tensile strength, elongation, and water resistance and having a good balance was obtained without generating gum-up, and the present invention was completed based on this finding.

[0004]

Thus, according to the present invention, an ethylenically unsaturated carboxylic acid and other monomers copolymerizable therewith are emulsified in the presence of a polymerizable surfactant. Neutralized product of alkali-soluble polymer obtained by polymerization 10
There is provided a paper impregnating composition containing an aqueous polymer dispersion obtained by emulsion polymerization of 100 parts by weight of a monomer mixture in the presence of 200 parts by weight as an essential component. According to the present invention,
An impregnated paper obtained using the paper impregnating composition is provided.

The aqueous polymer dispersion, which is an essential component of the paper impregnating composition of the present invention, is a neutralized product of an alkali-soluble polymer.
It is obtained by emulsion polymerization of 100 parts by weight of the monomer mixture in the presence of 0 to 200 parts by weight.

[0006] The alkali-soluble polymer is obtained by polymerizing an ethylenically unsaturated carboxylic acid and other monomers copolymerizable therewith.

The ethylenically unsaturated carboxylic acids include ethylenically unsaturated monocarboxylic acids such as acrylic acid, methacrylic acid and crotonic acid; and ethylenically unsaturated polyvalent such as fumaric acid, maleic acid, itaconic acid and butenetricarboxylic acid. Carboxylic acids; examples include partial esterified products of ethylenically unsaturated polycarboxylic acids such as monoethyl maleate and monomethyl itaconate. Among these ethylenically unsaturated carboxylic acids, ethylenically unsaturated monocarboxylic acids such as (meth) acrylic acid are preferred.

The amount of the ethylenically unsaturated carboxylic acid is such that the acid value of the alkali-soluble polymer is usually in the range of 50 to 300, preferably 80 to 250. Usually, 5 to 5 of all monomers used to obtain an alkali-soluble polymer
50% by weight. When the amount of the ethylenically unsaturated carboxylic acid is less than 5% by weight, the acid value of the alkali-soluble polymer becomes small, and the alkali-soluble polymer is not dissolved in water even when neutralized, so that the aqueous polymer dispersion The aqueous polymer dispersion cannot be obtained because the emulsion stability at the time of emulsion polymerization decreases. Conversely, when the amount of the ethylenically unsaturated carboxylic acid used is more than 50% by weight, the water resistance of the impregnated paper obtained by using the paper impregnating composition decreases. The acid value is a value obtained by the evaluation method described later.

Other monomers copolymerizable with the ethylenically unsaturated carboxylic acid include methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, and n- (meth) acrylate. Amyl, isoamyl (meth) acrylate, hexyl (meth) acrylate, ethylhexyl (meth) acrylate, ethylenically unsaturated carboxylic acid alkyl ester monomers such as octyl (meth) acrylate; styrene, α-methylstyrene, Aromatic vinyl monomers such as vinyl toluene and chlorostyrene; hydroxyl-containing ethylenically unsaturated monomers such as hydroxyethyl (meth) acrylate and hydroxypropyl (meth) acrylate; glycidyl (meth) acrylate, allyl glycidyl Glycidyl group-containing ethylenically unsaturated monomers such as ethers; (meth) acryloyl Cyano group-containing ethylenically unsaturated monomers such as tolyl; amide group-containing ethylenically unsaturated monomers such as (meth) acrylamide, N-methylol (meth) acrylamide, N-butoxymethyl (meth) acrylamide; 3-butadiene, isoprene, 2,3
Conjugated diene monomers such as -dimethyl-1,3-butadiene and 1,3-pentadiene; vinyl halides such as vinyl chloride; and carboxylic acid vinyl esters such as vinyl acetate. These monomers can be used alone or in combination of two or more. Among these monomers, ethylenically unsaturated carboxylic acid alkyl ester monomers such as methyl (meth) acrylate and ethyl (meth) acrylate are preferred.

The alkali-soluble polymer used in the present invention is:
Its weight average molecular weight is usually 1,000 to 20,000.
0, preferably 2,000 to 15,000, and more preferably 5,000 to 10,000. When the weight average molecular weight is less than 1,000, the polymerization stability of the aqueous polymer dispersion decreases, and the sizing degree of the impregnated paper obtained using this dispersion decreases. On the other hand, when it is larger than 20,000, the viscosity of the aqueous polymer dispersion becomes high, which is not suitable for practical use. The weight average molecular weight is a value obtained by the method described below.

The alkali-soluble polymer used in the present invention is:
Its glass transition temperature is usually 0 to + 200 ° C, preferably 0 to + 150 ° C. Below 0 ° C., the tensile strength of the impregnated paper decreases. Conversely, if the temperature exceeds + 200 ° C., the elongation of the impregnated paper decreases, and the texture becomes hard, which is not practical.

[0012] The alkali-soluble polymer is obtained by emulsion polymerization in the presence of a polymerizable surfactant.

[0013] Polymerizable surfactants are surfactants having one or more polymerizable carbon-carbon unsaturated bonds in the molecule. Specific examples thereof include sodium propenyl-2-ethylhexylbenzenesulfosuccinate,
Anionic polymerizable surfactants such as polyoxyethylene sulfate (meth) acrylate, ammonium polyoxyethylene alkylpropenyl ether sulfate, and phosphate ester of (meth) acrylic acid polyoxyethylene ester; polyoxyethylene alkylbenzene ether ( Nonionic polymerizable surfactants such as (meth) acrylates and polyoxyethylene alkyl ether (meth) acrylates are exemplified. The amount of the polymerizable surfactant is usually from 0.01 to 1: 1 based on 100 parts by weight of all monomers used for the synthesis of the alkali-soluble polymer.
0 parts by weight, preferably 0.05 to 0.8 parts by weight.
If the amount is less than 0.01 part by weight, emulsification of the monomer becomes impossible and emulsion polymerization of the alkali-soluble polymer becomes impossible. Conversely, if it exceeds 1.0 part by weight, the sizing and water resistance of the impregnated paper obtained using the aqueous polymer dispersion decrease.

The neutralized alkali-soluble polymer is obtained by neutralizing the alkali-soluble polymer to a neutralization degree of 70% or more with a basic substance. As the basic substance, ammonia; amines such as methylamine, ethylamine, isopropylamine, dimethylamine, N, N-dimethylethanolamine, diisopropylamine, trimethylamine, and triethanolamine; hydroxides of alkali metals such as sodium hydroxide And the like. Of these, ammonia is preferred.

The monomer mixture is usually a combination of the following monomers, preferably an ethylenically unsaturated monomer containing a glycidyl group, an amide group or an amino group, and a copolymerizable with the same. And a combination of various monomers.

The ethylenically unsaturated monomer containing a glycidyl group, an amide group or an amino group used in the monomer mixture includes glycidyl group-containing ethylenically unsaturated monomers such as glycidyl (meth) acrylate and allyl glycidyl ether. Amide group-containing ethylenically unsaturated monomers such as (meth) acrylamide, N-methylol (meth) acrylamide, N-butoxymethyl (meth) acrylamide;
Examples include amino group-containing ethylenically unsaturated monomers such as dimethylaminoethyl (meth) acrylate and diethylaminoethyl (meth) acrylate. The amount of these monomers is usually 0.5 to 15% by weight, preferably 1 to 10% by weight of the monomer mixture. If it is less than 0.5% by weight,
The water resistance and tensile strength of the impregnated paper decrease. 15% by weight
If it exceeds, the viscosity of the paper impregnating composition will be high, which is not practical.

The monomers copolymerizable with the ethylenically unsaturated monomer containing a glycidyl group, an amide group or an amino group used in the monomer mixture include (meth) acrylonitrile and β- (meth) acrylate. Cyano group-containing ethylenically unsaturated monomer such as cyanoethyl; hydroxyl-containing ethylenically unsaturated monomer such as hydroxyethyl (meth) acrylate and hydroxypropyl (meth) acrylate; pyridyl group such as 2-vinylpyridine Ethylenically unsaturated monomers; aromatic vinyl monomers such as styrene, α-methylstyrene, vinyltoluene, and chlorostyrene; methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, N-Amyl (meth) acrylate, (meth)
Isoamyl acrylate, hexyl (meth) acrylate,
Ethylenically unsaturated carboxylic acid alkyl ester monomers such as ethylhexyl (meth) acrylate and octyl (meth) acrylate; 1,3-butadiene, isoprene,
Conjugated diene monomers such as 3-dimethyl-1,3-butadiene and 1,3-pentadiene; vinyl halide monomers such as vinyl chloride; and carboxylic acid vinyl esters such as vinyl acetate.

The copolymer obtained by polymerizing the monomer mixture has a glass transition temperature of usually -80 to + 200 ° C, preferably -75 to +150.
° C, more preferably -40 to + 80 ° C. -80
If the temperature is lower than ℃, the tensile strength of the impregnated paper decreases. Conversely +20
If the temperature exceeds 0 ° C., the elongation and tensile strength of the impregnated paper decrease. ,

The ratio of the neutralized alkali-soluble polymer to the monomer mixture is based on 100 parts by weight of the monomer mixture.
10 to 200 parts by weight of a neutralized alkali-soluble polymer,
Preferably it is 20 to 150 parts by weight. If the neutralized product of the alkali-soluble polymer is less than 10 parts by weight, gum up is likely to occur, and the sizing degree of the obtained impregnated paper decreases. Conversely, if the neutralized product is more than 200 parts by weight, the elongation of the impregnated paper and the water resistance are reduced.

Emulsion polymerization of the monomer mixture in the presence of a neutralized alkali-soluble polymer may be carried out by adding the monomer mixture into an aqueous medium containing the neutralized polymer,
After mixing the neutralized product and the monomer mixture to form an emulsion, the mixture is added to an aqueous medium or an aqueous medium containing the neutralized product, and polymerized. The polymerization temperature is from 0 to 100C, preferably from 30 to 90C.

In the emulsion polymerization of the monomer mixture in the presence of the neutralized product of the alkali-soluble polymer, in order to enhance the polymerization stability, less than 0.05% by weight, preferably 0% by weight, based on the monomer mixture. Less than 0.02% by weight of surfactant can be used. However, if the amount of the surfactant is 0.05
When the content is more than the weight%, the sizing degree of the impregnated paper decreases.

The aqueous polymer dispersion liquid, which is an essential component of the paper impregnating composition of the present invention, has a glass transition temperature of the copolymer constituting the aqueous polymer dispersion of usually -60 to + 120 ° C, preferably-.
50 to + 100 ° C, more preferably -50 to + 30 ° C
It is. If the temperature is lower than −60 ° C., the tensile strength of the impregnated paper decreases. Conversely, if the temperature exceeds + 120 ° C., the elongation and tensile strength of the impregnated paper decrease.

The paper impregnating composition of the present invention may contain, if necessary, an impregnation accelerator such as methanol or isopropanol; an antifoaming agent; a waterproofing agent; and a thickener.

The impregnated paper of the present invention is obtained by using the above-mentioned composition for paper impregnation.

The base paper used for the impregnated paper of the present invention is usually base paper made of pulp such as mechanical pulp, chemical pulp, semi-chemical pulp or waste paper pulp; organic polymer fiber such as rayon fiber or polyester fiber. Base paper as a raw material; base paper made from inorganic fibers such as asbestos fiber, ceramic fiber, glass fiber, metal fiber, and carbon fiber;

In the impregnated paper of the present invention, the ratio of the composition for paper impregnation to the base paper is such that the composition for paper impregnation is based on the base paper.
It is usually 10 to 50% by weight in terms of solid content. If it is less than 10% by weight, the water resistance, tensile strength, etc. of the impregnated paper will be reduced. Conversely, even if it exceeds 50% by weight, the characteristics of the impregnated paper do not increase.

[0027]

By producing an impregnated paper using the paper impregnating composition of the present invention, it is possible to obtain an impregnated paper having excellent balance in size, tensile strength and water resistance without gum up. can get.

[0028]

The present invention will be described more specifically with reference to the following examples. The parts and percentages in the examples are on a weight basis.

[Evaluation Methods] The methods for evaluating various physical properties in the examples are as follows. (Glass transition temperature) An aqueous solution or aqueous polymer dispersion of a neutralized alkali-soluble polymer is cast on a framed glass plate,
The film was dried at 20 ° C. for 48 hours to obtain a film. Using a scanning differential calorimeter (manufactured by Seiko Instruments Inc., model RDC220), the film was heated at an initial temperature of −100 ° C. and a heating rate of 10 ° C./min. It was measured.

(Molecular Weight) An aqueous solution of a neutralized alkali-soluble polymer is cast on a glass plate with a frame and dried at 20 ° C. for 48 hours to obtain a film. The film is dissolved in tetrahydrofuran, and gel permeation is performed. It is determined as the weight average molecular weight in terms of polystyrene using chromatography.

(Acid value) Two drops of a phenolphthalein indicator were added to 1 g (in terms of solid content) of an emulsion of an alkali-soluble polymer, and the solution was titrated with a 0.1N aqueous solution of potassium hydroxide to obtain water required for neutralization. M of solid content of potassium oxide
Determined as g number.

(Mechanical Stability [Substitute Index for Gum-Up Occurrence]) 100 g of an aqueous polymer dispersion having a solid content of 40% was prepared using a Marlon mechanical stability tester (manufactured by Kumagaya Riki Co., Ltd.). After stirring with a load of 10 kg for 10 minutes, the mixture was filtered through an 80-mesh wire gauze, the dry weight of the aggregate remaining on the wire gauze was measured, and expressed as a ratio (%) to the solid content in the aqueous polymer dispersion. .

(Stekigt sizing degree) For impregnated paper,
It was measured according to JIS P 8140. That is,
The box-shaped folded impregnated paper was floated on a 1% ammonium thiocyanate aqueous solution, and at the same time, a drop of 1% ferric chloride aqueous solution was dropped on the bottom of the box-shaped impregnated paper to change the color to red-brown. Was measured until three spots could be found with the naked eye.

(Normal tensile strength and elongation)
mm × 15 mm, and this was cut using a constant-speed tension-type tensile tester, with a distance between chucks of 50 mm and a tensile speed of 100 m.
The tensile strength and elongation at break were measured under the conditions of m / min and 25 ° C.

(Water resistant tensile strength and elongation [index of water resistance]) The impregnated paper was cut into 130 mm x 15 mm, immersed in water at 25 ° C for 1 hour, and then broken in the same manner as in the above tensile strength test. The tensile strength and elongation at the time were measured.

Reference Example 1 80 parts of ethyl acrylate, 20 parts of methacrylic acid, 5 parts of octyl thioglycolate, a polymerizable surfactant (polyoxyethylene alkylpropenyl ether sulfate ammonium salt, Aqualon HS10, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) ) 0.3 part and 50 parts of ion-exchanged water were mixed to obtain a monomer emulsion. On the other hand, after replacing the inside of the reactor with a stirrer with nitrogen, 200 parts of ion-exchanged water was charged and heated to 80 ° C., and 2 parts of potassium persulfate and 38 parts of ion-exchanged water were added to the reactor and maintained at 80 ° C. The monomer emulsion was continuously added to the reactor thus prepared for 1 hour to cause a reaction. After the addition of the monomer emulsion, the reaction was further performed for 1 hour to obtain an emulsion of the alkali-soluble polymer (A). Table 1 shows the glass transition temperature, acid value and weight average molecular weight of the alkali-soluble polymer (A). Further, 14 parts of 28% aqueous ammonia was added to the emulsion of the alkali-soluble polymer (A), and stirring was continued for 30 minutes to obtain a 25% aqueous solution of the neutralized product (A).

REFERENCE EXAMPLES 2-3 The alkali-soluble polymer was prepared in the same manner as in Reference Example 1 except that the monomers used in the synthesis of the alkali-soluble polymer of Reference Example 1 were changed to the monomers shown in Table 1. The emulsions (B) to (D) were obtained. Table 1 shows the polymerization conversion, acid value and weight average molecular weight of these alkali-soluble polymers. In addition, 28 of these alkali-soluble polymer emulsions
% Of aqueous ammonia (B)
A 25% aqueous solution of (D) was obtained.

[0038]

[Table 1]

Example 1 A reactor equipped with a stirrer and purged with nitrogen was charged with 150 parts of ion-exchanged water and neutralized with an alkali-soluble polymer (A) 25.
Parts, 1 part of dimethylaminoethanol, 55 parts of styrene,
40 parts of butadiene, 5 parts of glycidyl methacrylate and 0.05 part of tetrasodium ethylenediaminetetraacetate were added and mixed to obtain an emulsion. This was heated to 50 ° C., and 10 parts of a 0.5% aqueous solution of potassium persulfate was added, and the mixture was reacted at 50 ° C. for 10 hours. After the reaction, unreacted monomers are removed, and aqueous ammonia is added to adjust the pH.
An aqueous polymer dispersion of 7.5 was obtained. The solid content concentration of this aqueous polymer dispersion was adjusted to 40% to obtain a paper impregnating composition.

Next, No. 2 filter paper (basis weight 120g /
m ² ) was immersed in the paper impregnating composition, and the excess composition was squeezed out with a roll and dried at 130 ° C. for 5 minutes to obtain an impregnated paper having a basis weight of 24 g / m ² . Table 1 shows the evaluation results of the impregnated paper.

Examples 2 to 6 and Comparative Examples 1 and 2 The procedure of Example 1 was repeated except that the neutralized product (A) or the monomer mixture was replaced with the neutralized product or the monomer mixture shown in Tables 1 and 2. An aqueous polymer dispersion and a composition for paper impregnation were obtained in the same manner as in the method, and an impregnated paper was obtained in the same manner as in Example 1 using this composition.
The evaluation results of these impregnated papers are shown in Tables 1 and 2.

COMPARATIVE EXAMPLE 3 Sodium dodecylbenzenesulfonate 2.0 was used in place of 25 parts of the alkali-soluble polymer neutralized product in Example 1.
An aqueous polymer dispersion was obtained in the same manner as in Example 1 except for using parts, and an impregnated paper was obtained in the same manner as in Example 1 using this composition. Table 2 shows the evaluation results of the impregnated paper.

Comparative Example 4 The neutralized product of the alkali-soluble polymer obtained in Reference Example 1 was adjusted to a solid concentration of 20% instead of the aqueous polymer dispersion in Example 1, and the composition for impregnation was prepared. Then, using this composition, an impregnated paper was obtained in the same manner as in Example 1. Table 2 shows the evaluation results of the impregnated paper.

[0044]

[Table 2]

From the above, it can be seen that by using the impregnating composition of the present invention, an impregnated paper excellent in size, tensile strength, elongation and water resistance and having a good balance among them can be obtained.

────────────────────────────────────────────────── ─── Continuing from the front page (72) Inventor Kuniyoshi Tashiro 1-2-1 Yakko, Kawasaki-ku, Kawasaki-shi, Kanagawa Japan Zeon Co., Ltd. Research and Development Center Examiner Yoko Nakajima (56) References JP-A-4-91295 ( JP, A) (58) Field surveyed (Int. Cl. ⁷ , DB name) D21H 11/00-27/42

Claims (3)

(57) [Claims] Claims: 1. An ethylenically unsaturated carboxylic acid and another monomer copolymerizable therewith with a polymerizable surfactant.
In the presence of 10 to 200 parts by weight of a neutralized alkali-soluble polymer obtained by emulsion polymerization in the presence of
A paper impregnating composition comprising, as an essential component, an aqueous polymer dispersion obtained by emulsion polymerization of parts by weight. 2. The monomer mixture according to claim 1, comprising an ethylenically unsaturated monomer containing a glycidyl group, an amino group or an amide group, and a monomer copolymerizable therewith. The composition for paper impregnation according to claim 1, characterized in that: 3. An impregnated paper obtained by using the paper impregnating composition according to claim 1.