JPH07109691A - Additive for paper manufacturing - Google Patents

Abstract

PURPOSE:To obtain an additive improving the tensile strength and intralayer strength of paper in its drying, also presenting excellent effect in terms of tear strength. CONSTITUTION:This additive for paper manufacturing contains, as active ingredient, a graft polymer produced by polymerizing, a monomer mixture composed of an acrylamide and/or methacrylamide, an anionic vinyl monomer, a crosslinkable vinyl monomer and, as necessary, a cationic vinyl monomer in an aqueous solution containing cationic starch.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an additive for papermaking, and more particularly, it has excellent tensile strength when the paper is dried and is sufficiently satisfactory in various strengths such as the strength in the paper layer and tear strength. Related to additives for cosmetics.

[0002]

2. Description of the Related Art In the papermaking process, various papermaking additives have been conventionally used for the purpose of improving paper quality. For example, cationic starch, α-modified starch, modified starch such as oxidized starch, or acrylamide polymer and its derivative,
Polyamide polyamine epichlorohydrin resins, melamine and urea formaldehyde resins etc. are used depending on the required purpose.

Although modified starch is inexpensive, it has to be used in a large amount because it has a poor effect of increasing paper strength per amount used, and needs to be steam-dissolved before use. Instead, from the viewpoint of workability and performance, synthetic polymer additives are preferred. A typical synthetic polymer additive is an acrylamide-based polymer, which is a Mannich reaction product of an anionic acrylamide-based polymer and polyacrylamide, and a cationic (amphoteric) acrylamide-based polymer obtained by a Hoffmann decomposition reaction,
Alternatively, there are cationic (amphoteric) acrylamide copolymers which copolymerize (meth) acrylamide with an anionic vinyl monomer and a cationic vinyl monomer.

Although acrylamide polymers have excellent performance as dry paper strength agents, their use is economically restricted because they are expensive.

Additives that combine the properties of acrylamide polymers and starch additives are also known in the art. For example, Japanese Examined Patent Publication No. 38-17051 teaches a papermaking additive obtained by polymerizing an unsaturated amide and an unsaturated carboxylic acid in the presence of a water-dispersible polysaccharide. Further, Japanese Patent Publication No. 50-12481 discloses a graft starch-polymerized acrylamide obtained by polymerizing acrylamide and an unsaturated carboxylic acid in the presence of at least one of water-soluble water-dispersible polysaccharides and derivatives thereof as a main monomer component. Paper strength agents comprised of specific copolymer blends are taught. In addition to this, JP-A-63-29696 discloses a paper strengthening agent obtained by polymerizing a monomer mixture of dialkyl (meth) acrylamide with (meth) acrylic acid and (meth) acrylamide in an aqueous solution of starch. There is.

Furthermore, JP-A-2-26994 and JP-A-4-50395 describe that (meth) acrylamide and α. A graft starch polymer obtained by polymerizing a monomer composed of β-unsaturated carboxylic acid (salt) or hydroxy (meth) acrylate enhances tensile strength and in-layer strength, and at the same time improves tear strength. A possible papermaking additive is disclosed.

[0007]

Needless to say, general strength is required for paper, but tear strength is an important requirement for paper. For example, paper used for kraft paper, kraft adhesive tape, etc. is required to have particularly high tensile strength, in-layer strength and tear strength, which will be described later.

The above-mentioned acrylamide type paper strengthening agent is effective in improving the strength of the paper when it is dried, but has a drawback of lowering the tear strength. On the other hand, although the starch-based paper strengthening agent does not lower the tear strength as much as the acrylamide-based paper strength enhancer, it has a poor effect of increasing various strengths in general, and therefore has a drawback that it must be used in a large amount.
Further, polyamide polyamine-epiclohydrin resin, melamine, urea formaldehyde resin and the like have a defect that the disintegration of broke is difficult in addition to the defect that tear strength is lowered. On the other hand, the above-mentioned JP-A-2-26994
The papermaking additives disclosed in JP-A No. 4-50395 and JP-A No. 4-50395 improve general strengths of papers and lower the tear strength to a small extent. However, tensile strength,
In terms of strengthening various strengths such as in-layer strength, satisfactory results cannot always be obtained, and there is still room for improvement.

It is an object of the present invention to provide a new papermaking additive capable of improving the tensile strength and the in-layer strength especially when dried and producing a paper which is sufficiently satisfactory in terms of tear strength. It is a thing.

The intra-layer strength referred to in the present invention indicates the strength in the thickness direction of paper and has a close relationship with the interfiber bond strength. This is also described in “Pulp and Paper Pulps and Their Testing Methods” edited by Japan Pulp and Paper Institute, page 248.
In the present invention, the in-layer strength was measured in accordance with the "measurement method using a tensile strength tester" described in the same document. The measuring method will be briefly described below.

As shown in FIG. 1, adhesive tapes were adhered to both sides of the test piece so that they adhered to each other, and then both ends of the adhesive tape were separated from each other as shown in the figure to form a T shape, and the upper and lower grips of a light load tensile tester Fixed at a low speed (50-100 mm /
Min) is the maximum load when peeling a certain distance.

[0012]

[Figure 1]

[Means for Solving the Problems] As a result of intensive studies aimed at improving a graft starch polymer-based additive for papermaking, the present inventors have found that a specific vinyl monomer is added in an aqueous solution containing a cationic starch. It was found that the polymer obtained by graft polymerization serves as a novel papermaking additive that can achieve the intended purpose.

That is, according to the present invention, in an aqueous solution containing a cationic starch, (a) acrylamide and / or methacrylamide (b) anionic vinyl monomer (c) crosslinkable vinyl monomer (d) optionally cationic It is intended to provide a papermaking additive containing a graft polymer obtained by polymerizing a monomer mixture composed of vinyl monomers as an active ingredient.

Particularly in an aqueous solution containing 20 to 80 parts by weight of cationic starch, (a) acrylamide and / or methacrylamide 40 to 98.5 mol% (b) anionic vinyl monomer 2 to 30.0 mol% A graft polymer obtained by polymerizing 80 to 20 parts by weight of a monomer mixture (c) 0.02 to 10.0 mol% of crosslinkable vinyl monomer (d) 0 to 20.0 mol% of cationic vinyl monomer is obtained. By adding an additive for papermaking, which is an active ingredient, to the raw material pulp slurry and making the paper in the usual way, and drying, it has excellent tensile strength and in-layer strength,
At the same time, it is an object of the present invention to provide a papermaking additive capable of stably maintaining tear strength at a high level.

In the present invention, the cationic starch is, for example, starch such as corn, wheat, potato, rice, tapioca and the like, which comprises primary, secondary and tertiary amino groups and a quaternary ammonium group. It contains at least one kind of basic nitrogen selected from the group. The basic nitrogen content is preferably 0.3% by weight or more, the quaternary ommonium group is most preferable as the basic nitrogen, and tapioca starch is most preferable as the starch. Also, an amphoteric starch obtained by introducing an anionic group (for example, a phosphoric acid ester group) into the above-mentioned cationic starch can be used.

As the anionic vinyl monomer of the present invention, acrylic acid, methacrylic acid, itaconic acid, maleic anhydride, vinyl sulfonic acid, 2-acrylamido-2-
Methyl propane sulfonic acid, its sodium salt, potassium salt, ammonium salt, etc. are mentioned.

Typical examples of the crosslinkable vinyl monomer of the present invention include methylol acrylamide,
N. N-dimethyl acrylamide, methylene bis (meth) acrylamide as bis (meth) acrylamide, ethylene bis (meth) acrylamide, ethylene glycol di (meth) as bifunctional vinyl monomer
Di (meth) acrylates such as acrylate diethylene glycol di (meth) acrylate, tothiethylene glycol di (meth) acrylate, divinyl adipate divinyl sebacate divinyl esters, epoxy acrylate -, Urethane acrylates, divinylbenzene, and trifunctional monomers, 1.3.5 triacryloylhexahydro-S-triazine, triallyl isocyanurate, triallyl trimellitate, N ． Examples of N-diallyl acrylamide and tetrafunctional vinyl monomers include tetramethyl methane tetraacrylate and tetraallyl pyromellitate.

Examples of the cationic vinyl monomer of the present invention include dimethylaminoethyl acrylate, dimethylaminoethyl methacrylate, diethylaminoethyl acrylate, diethylaminoethyl methacrylate, dimethylaminopropyl acrylamide and dimethyl. Examples thereof include vinyl monomers having a tertiary amino group such as aminopropylmethacrylamide or salts thereof, and quaternary ammonium salts.

In addition to the above-mentioned monomers, nonionic vinyl monomers such as (meth) acrylic acid ester, styrene and vinyl acetate which are copolymerizable therewith can also be used within a range not substantially impairing the effects of the present invention. .

The graft starch polymer of the present invention can be produced by various conventionally known methods. For example, a reaction vessel equipped with a stirrer and a nitrogen gas introduction tube is charged with an aqueous solution of cationic starch, which is a constituent of the present invention, each of the above-mentioned monomer components (a) (b) (c) (d) and water. ,
Hydrogen peroxide, ammonium persulfate, potassium persulfate, peroxides such as ammonium hydroperoxide as a polymerization initiator, or any redox comprising a combination of these peroxides with a reducing agent such as sodium bisulfite. An initiator, and further, a water-soluble azo initiator such as 2.2′-azobis (2-amidinopropane) hydrochloric acid is used, and the reaction is carried out at a reaction temperature of 40 to 80 ° C. for 1 to 5 hours to produce a zwitterionic property. The graft starch polymer may be obtained.

As the crosslinkable vinyl monomer of the present invention, N,
When N dimethyl acrylamide is used, it is necessary to add an oxidizing radical catalyst to the graft starch polymer containing N, N dimethyl acrylamide obtained by the above-mentioned polymerization method to carry out a crosslinking reaction. Examples of the oxidizing radical catalyst include hydrogen peroxide, inorganic peroxides such as persulfates (ammonium persulfate, potassium persulfate, etc.), ketone peroxides, peroxyketals, hydroperoxides,
Examples thereof include organic peroxides such as diacyl peroxide, peroxycarbonate and peroxyester.
Oxidizing radical catalyst is N, N dimethylacrylamide 1
It is used in an amount of 0.1 to 1 mol per mol.

The papermaking additive of the present invention has a solid content of about 10 to 2
It is produced in the form of an aqueous dispersion of about 0% by weight, and when it is used for papermaking, it is 0.05 to 10%, preferably 0.1 to 3%, based on the dry weight of pulp in terms of solid content. It is possible to improve various strengths such as tensile strength, in-layer strength and tear strength when the paper is dried by adding it to the raw material pulp in an amount corresponding to, and making and drying the paper in the usual way.

The following are examples of the papermaking additive of the present invention,
Application examples and comparative examples will be shown.

Example 1 150 g of an aqueous solution of cationic tapioca starch (nitrogen content 0.42%) having a concentration of 18% cooked at 90 to 100 ° C., 60 g of acrylamide having a concentration of 40%, acrylic acid having a concentration of 80% 3. 4g, water 150
g of the mixed solution was adjusted to pH 4.0 with a 10% potassium hydroxide solution, and then 0.4 g of N, N dimethylacrylamide was added.
Add.

Next, 2.7 ml of a 2% aqueous solution of ammonium persulfate (APS) and 2.7 ml of a 2% aqueous solution of sodium bisulfite (SBS) were added at a temperature of 50 ° C., and the mixture was mixed at a temperature of 60 to 80 ° C. for 3 days.
The reaction was carried out for a time to obtain a graft polymer.

Next, 4.4 g of 10% ammonium persulfate
After the addition, the mixture was reacted at 70 to 80 ° C. for 4 hours, 80 g of water was added, and the pH was adjusted to 6 to 7 with a 10% aqueous potassium hydroxide solution to obtain a zwitterionic graft starch polymer. The results are shown in Table 1.

[0027]

[Table 1] [Example 2] Concentration of 17 cooked at 90 to 100 ° C
% Cationic tapioca starch (0.42% nitrogen content)
Aqueous solution 197.5g, 40% concentration of acrylamide 70
g, 80% concentration acrylic acid 4.1 g, dimethylaminopropylacrylamide 1.4 g, and water 180 g were mixed to prepare pH 4.0 after using 10% caustic potash solution.
Add 0.9 g of N-methylolacrylamide. Next, at a temperature of 50 ° C., 2.5 ml of 2% APS and 2% SBS
After adding 2.5 ml and reacting at a temperature of 60 to 80 ° C. for 3 hours, and then adding 110 g of additional water, the pH was adjusted to 6 to 7 with a 10% aqueous potassium hydroxide solution to give a zwitterionic graft starch polymer. Obtained. The results are shown in Table 1. [Examples 3 to 5] Both ions were prepared in the same manner as in Example 2 except that the types of components (a) to (d) or their composition (mol%) were changed as shown in Table 1. A grafted starch polymer was obtained. The properties are also shown in Table 1.

Comparative Examples 1 to 3 (a) in Example 2
Table 1 shows types of (c) components or their composition (mol%).
A zwitterionic graft starch polymer was obtained in the same manner as in Example 2 except that the above was changed. The properties are also shown in Table 1.

[Applications 1 to 5] N-UKP (CSF53
0 ml) pulp slurry with COLOPAR E-5 (rosin emulsion size / concentration 50%: manufactured by Hoshi Kogaku Kogyo Co., Ltd.) 0.15% by weight of pulp and sulfuric acid band 1.8% by weight of pulp. Example 1 (1-5)
The amount of the zwitterionic graft starch obtained in step 1 is 0.5 based on the weight of pulp.
%, Added and mixed well. The adjusted pulp slurries thus obtained were made into paper having a basis weight of 75 / m ² by a TAPPI standard sheet machine, and 3.5k
After pressing at g / cm ² for 5 minutes, it was dried at 105 ° C. for 1.5 minutes.

The respective handmade papers thus obtained were prepared and subjected to a paper quality test. The test results are shown in Table 2.

[0031]

[Table 2] [Comparative Application Examples 1 to 3] Hand-made papers were obtained in the same manner as in the above-mentioned Application Examples except that Comparative Examples 1 to 3 were used instead of the zwitterionic graft starch polymer used in the Application Examples. A paper quality test was conducted on this handmade paper. The results are also shown in Table 2.

[Reference Example 1] Instead of the zwitterionic graft starch polymer used in the application example, Stargum A-15 (anionic acrylamide paper strength enhancer, concentration: 15%; manufactured by Hoshiko Chemical Co., Ltd.) was used. A handmade paper was obtained in the same manner as in the above-mentioned application except that it was used. A paper quality test was also performed on this handmade paper. The results are also shown in Table 2.

The paper quality measuring method is as follows.

Tensile strength (kg): JIS P-8113 Tear strength: JIS P-8116 In-layer strength (internal strength of paper): Described in “Types of Paper Pulp and Its Testing Methods” edited by Japan Pulp and Paper Institute, page 248. Conforms to "Measurement method using tensile strength tester".

Claims (3)

[Claims] 1. A monomer mixture comprising (a) acrylamide and / or methacrylamide (b) anionic vinyl monomer (c) crosslinkable vinyl monomer is polymerized in an aqueous solution containing a cationic starch. A papermaking additive containing the resulting graft polymer as an active ingredient. 2. A monomer comprising (a) acrylamide and / or methacrylamide, (b) an anionic vinyl monomer, (c) a crosslinkable vinyl monomer, and (d) a cationic vinyl monomer in a water-soluble solution containing a cationic starch. An additive for papermaking, which comprises a graft polymer obtained by polymerizing miscibility as an active ingredient. 3. In an aqueous solution containing 20 to 80 parts by weight of cationic starch, (a) acrylamide and / or methacrylamide 40 to 98.5 mol% (b) anionic vinyl monomer 2 to 30.0 mol % (C) Crosslinkable vinyl monomer 0.02 to 10.0 mol% (d) Cationic vinyl monomer 0 to 20.0 mol% A graft polymer obtained by polymerizing 80 to 20 parts by weight of a monomer mixture is obtained. An additive for papermaking that is an active ingredient.