JPS6259614A - Aqueous polymer dispersion - Google Patents

Abstract

PURPOSE:To form an aqueous polymer dispersion excellent in sizability, paper- strengthening property and paper maceratability, by emulsion-polymerizing a monomer mixture comprising acrylic acid, a vinylsilane compound and other copolymerizable ethylenically unsaturated monomers in the presence of a monomer imparting a cationic character or its homopolymer. CONSTITUTION:This dispersion is formed by emulsion-polymerizing a monomer mixture comprising acrylic acid (1) a vinylsilane compound or diallyl phthalate and a vinylsilane compound (2) and other copolymerizable ethylenically unsaturated monomer (3) in the presence of a monomer imparting a cationic character and/or its homopolymer. Examples of the said monomer include esters of (meth) acrylic acids, their salts and alkylamino group-containing vinyl ethers. Examples of component (3) include alkyl (meth)acrylates and ethylenically unsaturated aromatic monomers.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to an aqueous polymer dispersion. More specifically, by adding or impregnating a beater in the paper manufacturing process, it simultaneously gives the paper a size effect and increases paper strength. The present invention relates to an aqueous polymer dispersion suitable for paper manufacturing that can impart excellent disintegration properties to paper.

<Prior art and its problems> Conventionally, in paper manufacturing, melamine resin, polyacrylamide, polyamide, etc. have been used for the purpose of increasing paper strength.
Resins such as epichlorohydrin resin are used as paper strength agents.

However, these paper strength enhancers have the ability to strengthen paper strength, but do not have a size effect, so so-called sizing agents such as rosin and alkyl ketene dimer are required to provide a size effect. shall be. Incidentally, these sizing agents have no effect as the above-mentioned paper strength enhancer.

Therefore, for example, in the production of paper that requires low water absorption and high paper strength, such as original drawing paper, it is necessary to use a sizing agent and a paper strength enhancer in combination.

Paper that has a strong size effect, in other words, has low water absorption and has a strong paper strength due to the paper strength enhancer, is a waste paper,
Alternatively, in the waste paper recovery process, the above-mentioned properties make disintegration difficult, resulting in a problem of reduced production efficiency.

Generally, in such cases, sodium hypochlorite, modified phosphates, and the like are used as disintegration accelerators, but they actually have the disadvantage that they do not disintegrate easily.

The present invention provides a size effect and a paper strength enhancing effect by internally adding or impregnating paper with a sizing agent and a paper strength enhancing agent, and furthermore, in the disintegration process, a large amount of carbon a
As a result of extensive research into aqueous polymer dispersions for L, the resin itself dissolves in alkalis such as sodium hydroxide, giving paper the property of being easily disintegrated.
The present invention has now been completed.

Means for Solving the Problems〉 That is, the present invention provides a method for solving the problems of (11 acrylic acid, (2)
A vinyl silane compound, or diallylphthalate and a vinyl silane compound, and (3) other copolymerizable ethylenically unsaturated monomers are emulsion-polymerized. The purpose of the present invention is to provide an aqueous polymer dispersion that has excellent disintegration properties, particularly for use in sowing paper.

Examples of the cation-imparting tetramer used in the present invention include esters of (meth)acrylic MW such as N-methylaminoethyl ethyl acrylate or methacrylate, dimethylamine ethyl acrylate or methacrylate, or salts thereof; dimethylaminoethyl acrylate or methacrylate; Vinyl ether a having an alkylamino group such as ethyl vinyl ether; (meth)acrylamides having an alkylamino group such as N (2-dimethylaminoethyl)acrylamide or methacrylamide; 2-hydroxy-3-acryloxo or methacryloxypropyltrimethylammonium Included are α,β-ethylenically unsaturated monomers and homopolymers thereof that can form quaternary ammonium salts such as chloride.

The cation-imparting monomer or homopolymer thereof used in the present invention includes (11 acrylic acid, (2) a vinyl silane compound, or diallylphthalate and a vinyl silane compound, (3) other copolymerizable ethylenic monomers, and (3) other copolymerizable ethylenic monomers. For 100 parts by weight of a monolayer mixture consisting of saturated monomers, 0
．． It is best to use 5 to 30 parts by weight, and the amount used is 0.
．． If the amount is less than 5 parts by weight, when the obtained aqueous polymer dispersion is added to the valve slurry with a beater, it will not be sufficiently adsorbed to the pulp, and no paper strength enhancement effect or size effect will be obtained.

On the other hand, if it is used in an amount exceeding 30 parts by weight, the hydrophilicity of the aqueous polymer dispersion becomes excessively high and the size effect is reduced, which is not preferable.

In addition, the present invention enables emulsion polymerization without using commonly used emulsifiers, which can eliminate various troubles associated with foaming that occurs during paper processing processes, or improve the water resistance or water resistance of processed products. It is extremely effective in improving physical properties such as , size, etc. However, the method of the present invention does not preclude the use of commonly used emulsifiers, and emulsifiers may be used to the extent that the above-mentioned properties are not impaired.

The first component of acrylic acid used in the present invention is preferably used in an amount of 4 to 8% by weight based on 100 parts by weight of the sit mixture.

If the amount used is less than 4%, the alkali solubility will be weak and it will not be possible to impart the necessary disintegration properties to the yam. If more than 8% is used, emulsion polymerization will not proceed stably.

In the present invention, an ethylenically unsaturated carboxylic acid other than acrylic acid may be used in an amount of 2% or less. For example, monobasic acids such as methacrylic acid and crotonic acid, dibasic acids such as maleic acid, fumaric acid, itaconic acid, and their halfesters, etc.
It is used in an amount of 0.01 to 0.10% by weight.

If the amount used is less than 0.01% by weight, the effect of increasing paper strength will be small, and if it is used in excess of 0.10% by weight, the disintegrability will decrease.

The second component is a vinyl silane compound, or diallylphthalate and a vinyl silane compound, and examples of the vinyl silane compound include γ-methacryloxypropyltrimethoxysilane, vinyl-triethoxysilane, and vinyl-2-methoxyethoxysilane. The amount of these additions is 0. O1 to 0.10% by weight is good.

Examples of other copolymerizable ethylenically unsaturated monomers as the third component of the present invention include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, and (meth)acrylic acid. -n-butyl, (meth)acrylic acid alkyl ester, exemplified by (meth)acrylic acid-2-ethylhexyl, (meth)acrylic acid-2-
(meth)acrylic acid hydroxyalkyl esters exemplified by hydroxyethyl, 2-hydroxypropyl (meth)acrylate, etc., styrene, α-methylstyrene,
Ethylenically unsaturated aromatic monomers such as vinyltoluene; unsaturated nitriles such as (meth)acrylonitrile; vinyl esters such as vinyl acetate and vinyl propionate; (meth)acrylamide and N-methylol. Examples include radically polymerizable monomers such as (meth)acrylamide, N-butoxymethylacrylamide, diacetone acrylamide, and (meth)acrylic acid glycidyl ester, and one or two of these monomers can be used.
The species or more can be used in an amount of 90 to 95% by weight in the monomer mixture.

In the dispersion of the present invention, in the presence of the cation-imparting monomer or homopolymer thereof, the monomer mixture is
It is produced by radical copolymerization using a conventional method such as a batch charging method or a dropwise charging method under reaction conditions of 0.degree. C. for 5 to 24 hours, preferably 40.degree.

Since the aqueous polymer dispersion of the present invention has a low pH after polymerization, it prevents corrosion of metals and makes paper in a neutral range.
For the purpose of making neutral paper, it is neutralized with alkali to lower the pH to 4.
．． Adjust to 5-8.0. However, when neutralized using aqueous ammonia or sodium hydroxide as an alkali, the aqueous polymer dispersion tends to significantly thicken, so it is preferable to neutralize with disodium hydrogen phosphate or sodium hydrogen carbonate.

The dispersion of the present invention is a cellulose fiber (pulp slurry)
Not only is it excellent for paper making, but also other fibers such as rayon fibers, acetate fibers, polyester fibers, nylon fibers, mixtures of these fibers with cellulose fibers, carbon fibers, glass fibers, and ceramics. It can also be used as a binding agent for fibers, etc.

When the dispersion of the present invention is used for paper manufacturing, it can be used for wrapping paper, towels, paper sheets, original paper, wallpaper, etc., and can also be used for glass filters.

<Effects> The aqueous polymer dispersion of the present invention thus obtained has the following effects:
Applicable to internal addition method, dipping method, spray method, and coating method. For example, when used for internal addition of paper, pH 4.5 to 8.
．． It is possible to make paper in a wide 98-head range of 0, and it can be easily disintegrated in the waste paper and waste paper recovery process by raising the pH to 9 or higher with an alkali such as sodium hydroxide or aqueous ammonia. It has the characteristic that it does not require a disaggregation accelerator.

Alternatively, the aqueous polymer dispersion of the present invention can be added directly to the pulp slurry in the paper manufacturing process using a beater so that the solid content is 0.01 to 50% by weight based on the weight of cellulose fibers in the pulp slurry, or By impregnating it with , it brings about a size effect, a paper strength increasing effect, and an improvement in the disintegration property in the waste paper and waste paper recovery process, and the above-mentioned effects are also exhibited when used in coating.

Next, the present invention will be specifically explained with reference to Examples and Comparative Examples. In addition, in Examples and Comparative Examples, "part" means "part by weight", and "%" means "% by weight".

<Example> [Example 1-1] 2-Hydroxy-3-methacryloxypropyl-trimethylammonium chloride 4 was placed in a stainless steel reaction vessel equipped with a stirrer and equipped with a reflux condenser, a thermometer, and a dropping funnel.
part, 0.1 part t-dodecyl mercaptan and 1 part deionized water.
Add 20 parts and heat until the liquid temperature reaches 80℃, then add 1
Add 5.4 parts of 0% ammonium persulfate aqueous solution,
Stir for a minute.

Next, while keeping the temperature inside the container at 70°C, FeCIx,
Add 0.2 parts of 0.5% aqueous solution of 6HzO, 4.0% acrylic acid, 1.0% methacrylic acid, 0.1% diallylphthalate, 70.0% butyl acrylate, 24.9% methyl methacrylate. A polymerization catalyst solution in which 100 parts of a monomer mixture having the composition and 0.3 parts of t-butyl hydroperoxide were dispersed in 5 parts of deionized water was added dropwise over about 2 hours to carry out emulsion polymerization. During this time, the internal temperature was 70~
It was kept at 75°C.

It was then cooled to 40°C and 7% sodium hydrogen carbonate was added to adjust the pH to 4.0-5.5. After drying, deionized water was added to make the solid content concentration 45%. The obtained aqueous polymer dispersion had a solid content concentration of 45% and a viscosity of 2.
00c1)S (BM type 60rpII 125°C),
The pH was 4.3. Next, a predetermined amount of bleached kraft valve (NBKP/LBKP=1/l) was beaten in a Schopper-Riegler until it reached 30°SR, and then diluted with water to obtain a pulp slurry with a valve concentration of 1.6%.

Based on the weight of pulp fibers in this pulp slurry,
The above-mentioned aqueous polymer dispersion was added so that the resin solid content ratio was 2%, and the mixture was stirred for 1°, and then paper was made using a TAPPI standard machine. Moisture content of wet paper is 6o±
It was compressed and dehydrated under conditions of 1%, and then dried at 100° C. for 5 minutes to obtain a paper stock with a tsubo size of 5#61±Ig/M. After conditioning the humidity of this paper stock for 24 hours in a thermostatic chamber at 20° C. and 65% RH, various physical properties were measured and shown in Table 1.

As shown in Table 1, it was confirmed that the paper processed using the aqueous polymer dispersion of the present invention was extremely excellent in strength, sizing, and disintegration properties.

[Example 1-2] As base paper, unbleached double-sided kraft paper (basis weight 75g10f)
The fibers were impregnated with the aqueous polymer dispersion obtained in Example 1-1 to a resin content of 10% based on the weight of the pulp fibers, and then dried at 100° C. for 5 minutes. After this paper stock was conditioned for 24 hours in a constant temperature and constant room of 20"C and 165% RH, various physical properties were measured and shown in Table 2.

Note that the test method is the same as the method described in Table 1. As shown in Table 2, the strength, sizing, and disintegration properties of the impregnated paper treated with the dispersion of the present invention were excellent.

[Example 2-1] 8.0 parts of a 50% aqueous solution of dimethylaminoethyl methacrylate hydrochloride was used as the cation-imparting monomer, and the following composition was used as the monomer mixture. , by the same method as in Example 1-1, solid content concentration 45%,
Viscosity 180cps (BM type 60rpm 25℃),
An aqueous polymer dispersion of p) 14.2 was obtained.

(Composition of monomer mixture) Acrylic acid 5.00%, silane coupling agent (γ-
Methacryloxy-propyltrimethoxysilane) 0.
05%, methyl methacrylate 47.95%, acrylonitrile 7.00%, butyl acrylate 40.00%
.

Next, the paper was processed and its physical properties were measured in the same manner as in Example 1-1. As shown in Table 1, the paper treated with the dispersion of the present invention had excellent strength, sizing, and disintegration properties.

(Example 2-2) The aqueous polymer dispersion obtained in Example 2-1 was subjected to low impregnation processing in the same manner as in Example 1-2, and its physical properties were measured. As shown in Table 2, the paper treated with the dispersion of the present invention had excellent strength, sizing, and thinning properties.

[Example 3-1] Using monomers and mixtures with the following composition, 7% as a neutralizing agent
Example 1- except that disodium hydrogen phosphate was used.
Using the same method as 1, solid content concentration 45%, viscosity 200cp
s (BM type 60 rpm 25°C), an aqueous polymer dispersion with pi 44.2 was obtained.

(Composition of monomer mixture) Acrylic acid 5.00%, silane coupling agent (T-
Methacryloxy-propyltrimethoxysilane) 0.
05%, itaconic acid 1.00%, methyl methacrylate 43.95%, styrene 10.00%, butyl acrylate +-40,00%.

Next, the paper was processed in the same manner as in Example 1-1, and the physical properties of the paper were measured. As shown in Table 1, the paper treated with the dispersion of the present invention had excellent strength, sizing, and disintegration properties.

[Example 3-2] Example 1 was carried out using the polymer aqueous dispersion obtained in Example 3-1.
A low impregnation process was carried out in the same manner as in -2, and its physical properties were measured. As shown in Table 2, the paper treated with the dispersion of the present invention had excellent strength, sizing, and disintegration properties.

[Comparative Example 1-1] A sit substance mixture having the following composition was used, and the solid content concentration was 45% and the viscosity was 200 cps (
An aqueous polymer dispersion of BM type (60 rpm, 25° C.) and pl+4.2 was obtained.

(Composition of monomer mixture) Methacrylic acid 3.00%, silane-camping agent (T
-Methacryloxy-propyltrimethoxysilane)0
．． 05%, methyl methacrylate 46.95%, styrene 10.00%, butyl acrylate 40.00%.

Next, the paper was processed in the same manner as in Example 1-1, and its physical properties were measured. As shown in Table 2, the paper treated with the dispersion of Comparative Example 1-1 had excellent strength and sizing, but poor disintegration properties.

[Comparative Example 1-2] The aqueous polymer dispersion obtained in Comparative Example 1-1 was subjected to low impregnation processing in the same manner as in Example 1-2, and its physical properties were measured. As shown in Table 2, the grain treated with the dispersion of Comparative Example 1-1 had excellent strength and sizing, but poor disintegration properties.

[Comparative Example 2-1] Example 1-1 except that the monomer mixture had the following composition.
Solid content concentration 45%, viscosity 200 cps using the same method as 1.
(BM type, 60 rpm, 25°C), an aqueous polymer dispersion with a pH of 4.2 was obtained.

(Composition of monomer mixture) Acrylic f114.00%, methyl methacrylate 56
．． 00%, butyl acrylate 40. O0%.

Next, the paper was processed in the same manner as in Example 1-1, and its physical properties were measured. As shown in Table 1, the paper treated with the dispersion of Comparative Example 2-1 had Ai! Although the disintegration and sizing properties were excellent, the strength of the paper was poor.

[Comparative Example 2-2] Using the aqueous polymer dispersion obtained in Comparative Example 2-1, low impregnation processing and measurement of physical properties were performed in the same manner as in Example 1-2. As shown in Table 2, the paper treated with the dispersion of Comparative Example 2-2 had excellent disintegration properties and sizing, but poor paper strength.

[Comparative Examples 3 and 4] For comparison, as a conventional paper manufacturing method,
Comparative Example 3 uses a commercially available paper strength enhancer (cationic polyamide resin, [Boriaclone CMJ, manufactured by Hamano Industries, Ltd.]). ■
Comparative Example 4 was a combination system in which the product) and the fixing agent aluminum sulfate were added at a resin content of 2% based on the weight of the pulp fibers.

As shown in the results shown in Tables 1 and 2, compared to the aqueous polymer dispersion of the present invention, the paper obtained in Comparative Example 3.4 is?
W '14 □ It was found to be inferior in tensile strength, sizing, and disintegration 9 <Test method> +11 Dry tensile strength: The tensile strength of paper was measured according to JIS P 8113, and the tearing length (km) was displayed.

(2) Wet tensile strength: according to JIS P 8135,
The tensile strength of the paper was measured and expressed as breaking length (km).

(3) Steckicht size degree: JIS P 81
The sizing degree of the paper was measured by the Stekicht method according to 22, and expressed as the number of times it was folded.

(4) Folding strength: In accordance with JIS P 8115, the folding strength of paper was measured using a MET tester, and expressed as the number of times the paper was folded.

(5) Put a certain amount of paper stock into a pulp disintegrator (Tasoby Standard), add water so that the valve 4 degree is 1.6%, and add 7% sodium hydroxide solution or Adjust PL to 9 to 10 with sodium chlorite and stir for 5 minutes.

Next, this pulp slurry is put into a TAPP+ standard machine and paper is made so that the basis weight is 60±Ig/rrr. The formation of the paper stock after paper making was visually observed and determined.

<evaluation> ○: There are 3 or less small paper pieces of 2■■×2n.

Δ: Up to 4 to 10 small pieces of paper measuring 2 m x 2 am.

X: 11 or more small pieces of paper measuring 2m x 2mm.

Claims (1)

[Claims] In the presence of a cationic monomer and/or its homopolymer, (1) acrylic acid, (2) a vinyl silane compound, or diallylphthalate and a vinyl silane compound, (3) other copolymerizable ethylenic monomers. An aqueous polymer dispersion characterized by being formed by emulsion polymerization of a monomer mixture consisting of saturated monomers.