JPS6289714A - Anionic water-soluble copolymer for strengthening paper - Google Patents

Abstract

PURPOSE:The titled copolymer, containing specific unsaturated carboxylic acids as an anionic component and capable of exhibiting improved effect on dry paper strengthening by using together with aluminum sulfate, etc., when forming sheets of paper. CONSTITUTION:A copolymer, obtained by copolymerizing an anionic component consisting of two or more alpha,beta-unsaturated carboxylic acids (salts) and containing at least one of alpha,beta-unsaturated dicarboxylic acid (salt) with acrylamide in the presence of a water-soluble radical polymerization initiator, e.g. sodium persulfate, by an aqueous solution polymerization method. Maleic acid, etc., may be preferred for the above-mentioned alpha,beta-unsaturated dicarboxylic acid. 0.05-4wt%, expressed in terms of solid based on the dry weight of pulp, above- mentioned copolymer is preferably added to an aqueous dispersion of the pulp in using the above-mentioned copolymer.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to an anionic water-soluble copolymer for increasing paper strength, particularly for imparting an effect of increasing dry paper strength to paper.

[Technical background of the invention and its problems]

The supply of forest resources, which are raw materials for paper, is in short supply, and the use of recycled paper as an alternative raw material is increasing, and various paper strength enhancers are being used to compensate for the decline in paper strength caused by the combined use of recycled paper. There is. In addition, with the diversification of purposes, the need for various paper strength enhancers is increasing. Anionic lyacrylamide is a dry paper strength enhancer that has been widely used since ancient times and is still widely used today, and is used in combination with sulfuric acid and cationic or amphoteric resins to impart excellent paper strength. ing.

The anionic water-soluble copolymer for increasing paper strength of the present invention relates to the above-mentioned anionic I-lyacrylamide P-based paper strength agent, and may be hereinafter referred to as an anionic polyacrylamide copolymer.

Conventionally, many anionic preacrylamide copolymers are
Hydrolysis of polyacrylamide (co)polymers, or α, β-unsaturated monocals such as acrylic acid? It has been provided by a copolymer of phosphoric acid and acrylamide. Although such conventional anionic 4-lyacrylamide copolymers have a paper strength enhancing effect, it is still not sufficient, and if its quality, performance, and effectiveness can be further improved, its usefulness will be improved. It will increase further.

[Purpose of the invention]

The present invention has an excellent effect of increasing dry paper strength when used in combination with sulfuric acid, cationic or amphoteric resin, etc. in the paper making process, and has anionic properties that are superior to conventional anionic polyacrylamide copolymers. The purpose of the present invention is to provide a polyacrylamide copolymer.

[Summary of the invention]

As a result of intensive studies by the present inventors on the effects of anionic polyacrylamide-based paper strength agents, we found that they contain two or more types of α,β-unsaturated cargonic acids or salts thereof as anionic components, and these two or more types of α , β-unsaturated carboxylic acid or its salt is an α,β-unsaturated radical? The present inventors have discovered that anionic preacrylamide copolymers, which are phosphoric acid or its salts, have a superior dry paper strength enhancement effect compared to conventional anionic polyacrylamide copolymers, and have arrived at the present invention.

Although it is still not clear why such an effect is obtained, it is difficult to understand why such an effect is obtained, but it is difficult to explain why such an effect is obtained.
By using more than one type of vinyl caldic acid, the distribution of anionic sites in the polyacrylamide chain changes, and the number of types that can ionically react with each other with various cationic substances contained in the papermaking system increases, resulting in a wider range of possibilities. It is thought that as a result of creating more effective intermolecular bonds under papermaking conditions, a more excellent paper strength enhancing effect can be achieved.

α, β-unsaturated radical &71'l! according to the present invention! d, a polymerizable dibasic acid vinyl monomer having a double bond between the alpha and beta positions of one cargexyl group, such as maleic acid, fumaric acid, itaconic acid, citraconic acid, etc., or salts thereof; Examples include alkali metal salts and ammonium salts with caustic soda, caustic potash, etc., but maleic acid, fumaric acid, itaconic acid, or their salts are preferred from the economic standpoint. The anionic monomer to be copolymerized with the acrylamide of the present invention must contain the above α,β-unsaturated dicargenic acid or its salts, and other anionic monomers to be combined include α.

β-unsaturated monocarboxylic acids or their salts, or other α, β-unsaturated radicals? acid or their salts are used. Examples of α,β-unsaturated monocarboxylic acids include acrylic acid and methacrylic acid, and examples of their salts include alkali metal salts and ammonium salts of these α,β-unsaturated monocarboxylic acids with caustic soda, caustic potash, etc. is exemplified.

Regardless of the combination of these α,β-unsaturated nocargenic acids and other anionic monomers, the anionic water-soluble copolymer consisting of these anionic components and acrylamide is composed of the anionic monomer of 114 and acrylamide. Anionic water-soluble copolymer consisting of or 2f which does not contain α,β-unsaturated nocarboxylic acid! It can exhibit a paper strength enhancing effect superior to that of an anionic water-soluble copolymer composed of four or more anionic monomers and acrylamide. The amount of α, β-unsaturated cargen CFL or its salts used in the anionic water-soluble copolymer of the present invention is 0.1 to 2.0 meq/9·sol id as carboxyl fund amount.
, preferably 0.5 to 1.2 meq/Lsolid
It is.

The viscosity of the anionic polyacrylamide copolymer obtained by the present invention is 300 to 100.00 in the case of 10% by weight.
0 cps (25℃, Prutsk field viscosity)
In particular, the viscosity is soo~20.000 cps
The water-soluble copolymers are preferred as paper strength enhancers.

Also, vinyl monomers copolymerizable with these as copolymer components, such as methacrylamide, acrylonitrile, styrene, and methacrylic v! ¥! There is no problem in using methyl, vinyl acetate, etc. to the extent that they do not impair water solubility.

[Embodiments of the invention] The anionic z+7 acrylamide copolymer of the present invention,
The copolymerization reaction between acrylamide and anionic monomer can be carried out by various conventionally known methods. This can be accomplished by using a melting medium of 0.01 to 5 times + i to the total weight and carrying out aqueous solution polymerization. Redox polymerization can also be carried out using a reducing agent such as trimethylamine, sodium thiosulfate, sodium bisulfite, or natrirum formaldehyde sulfoxylate. At this time, it is obtained by adjusting the monomer concentration to 5 to 30% by weight in an aqueous medium and stirring at a temperature of 35 to 95°C for 1 to 10 hours. and allyl compounds such as allyl alcohol sodium allyl sulfonate, allyl amine, and inglovir alcohol.

An anionic I-lyacrylamide copolymer having a desired molecular weight can be synthesized by appropriately using a known chain transfer agent such as sodium hypophosphite. In addition, as a separate synthesis method of the present invention, α, β-unsaturated radical ? Of course, it is possible to introduce an acrylic acid type monocarboxylic acid group into the anion of the present invention by producing a copolymer of acrylamide containing phosphoric acid and partially hydrolyzing the amide group of the obtained copolymer. The polyacrylamide copolymer may be used in accordance with conventionally known methods. That is,
The anionic polyacrylamide copolymer of the present invention with a solid content weight ratio of 0.05 to 4 is added to the aqueous dispersion of Grug, based on the dry weight of 9. Paper making is carried out using both R# and fat in combination. Note that there is no problem in using a known sizing agent 9, paper strength enhancer, P water property improver, etc. in combination before papermaking.

Next, examples and application examples of the present invention will be given.

In the following, all references to 俤 are condescending, unless otherwise specified.

Example 1 617.6 mm of water was placed in a 11-four-bottle flask equipped with a stirrer, thermometer, reflux condenser, and nitrogen gas inlet tube. @, 50 acrylamide aqueous solution 253.9,9. Itakoni/[4,
8411,8047 17 A [aqueous solution 3.35.9.
24 Prepare sodium hypophosphite aqueous solution 15.4F,
Adjust to pi-14.0 with 15% sodium hydroxide aqueous solution)
After adjusting the temperature, nitrogen gas was introduced to remove oxygen from the reaction system.

Next, the temperature was raised to 60° C., and 4.2511 of an aqueous solution of ammonium persulfate was added to start the polymerization reaction.

After that, the temperature was kept at 75°C, and 1.5 hours after the start of polymerization, 5.
% ammonium persulfate aqueous solution was added, and the polymerization was further kept at 75°C for 1.5 hours to complete the polymerization. A stable aqueous copolymer solution of Nos. 4 and 7 was obtained, which is referred to as paper strength enhancer A.

Examples 2 to 12 A polymerization reaction similar to that in Example 1 was carried out by blending the constituent monomer components of the first coating to obtain an aqueous copolymer solution. These are referred to as paper strength enhancers B to P. The chain transfer agent 1 was changed as appropriate so that the viscosity of each copolymer was approximately the same.

Comparative Examples 1 to 12 A polymerization reaction similar to that in Example 1 was carried out using the constituent monomer components listed in Table 2, and an aqueous copolymer solution or α,β-unsaturated Nocal N7elR containing only one type of anion component was used.
An aqueous solution of two kinds of anionic copolymers was obtained. These are referred to as paper strength enhancers jl % p. In this case as well, the chain transfer agent was changed as appropriate.

The physical properties of the copolymers obtained in Examples and Comparative Examples were
It is shown in Table 2.

Table 1 Table 2 The monomer abbreviations in Tables 1 and 2 are as follows.

IA... MA itaconic acid... AA maleic acid... MAA acrylic acid... AAm methacrylic acid... Acrylamide Application example 1 Anionic properties of the present invention in a papermaking system using a small amount of sulfuric acid in combination with amphoteric resin In order to see the effect of polyacrylamide copolymer, Gulde (NUKP:C3F=409
1R1) 2.5 baseboard dispersion, paper strength enhancers A-F obtained in Examples and paper strength enhancers a obtained in Comparative Examples were added.
% f was added at 0.34 each, then sulfate was added at 0.54. 0.11% of Retin HM-133 (Mannic f-type amphoteric polyacrylamide resin, manufactured by Dick Vercules Co., Ltd.) was successively added. The addition rate is the weight ratio of the solid content to the dry Nt of the mother luzo. This was diluted to 0.254 and made into paper using a hand paper machine made by Nople & Wood. When making paper, pi (6,0),
Then, it was dried in a drum dryer at 110°C for 1.5 minutes to give a basis weight of 82±2ji/m" and 168±3.
Two types of hand-made paper with li'/m'' were obtained.

Also, using this 0.254-f death rally, DDT ■
was measured and the water resistance was investigated. The obtained paper stock was heated at 20℃, 6
After conditioning the humidity for 24 hours under the condition of 54RH, the former paper stock for tsubosake was determined to have a "specific bursting strength" according to JISP-8112, and the latter paper stock for (amount of paper stock) was determined for "specific compression strength" according to JISP-8126. The results are shown in Table 3.

The table also shows that the anionic polyacrylamide copolymer of the present invention exhibits an excellent paper strength enhancing effect and also has excellent water resistance.

Note) DDT Tappi Journal Volume 56, ffllO issue (
1973) @ page 46, “Dynam
Using a device similar to icDrainage Jar J, pour 800 rnl of Harges slurry into a jar with a diameter of approximately 7.5 cm, open the bottom cock while stirring at 800 rpm, filter through a 100 mesh wire mesh, and pour a certain amount of warm liquid into the jar. It measures the time it takes for F to become saturated, and can be used to evaluate F aqueous properties.

Here, the time required for P liquid volume to reach 259 ml was measured.

@Table 3 Application Example 2 In order to see the effect of a polyacrylamide copolymer with a higher anion content compared to the anionic polyacrylamide copolymer exemplified in Application Example 1, the results obtained in Examples and Comparative Examples were The P aqueous property (DDT), specific bursting strength, and specific compressive strength were measured using the same procedures as in Application Example 1 using the paper strength enhancers G to L and g-1. The results are shown in Table 4.

This table also shows that the anionic polyacrylamide copolymer of the present invention has an excellent paper strength enhancing effect. A comparison of the effects of exemplary anionic polyacrylamide copolymers is shown.

NUKP as Nokuruzo (C8F = 376 rrL
Perform the same operation as in Application Example 1 using D
DT).

Specific burst strength and specific compressive strength were measured. The results are shown in Table 5. The anionic polyacrylamide copolymers of the present invention have shown excellent performance over a wide range of molecular weights.

? yJ5 Table Application Example 4 The effect of using the anionic polyacrylamide copolymer of the present invention in combination with a polyamide/epichlorohydrin condensate which is a cationic resin was confirmed.・Enemy Rude (NU
To a 2.5-width aqueous dispersion of KP: C3F=375 rat) was added 0.34 of the paper strength enhancer obtained in the Examples and Comparative Examples, then 1.0% of sulfuric acid/gundo, and Kaimen 557. ) I (polyamide/epichlorohydrin condensate manufactured by Cures Co., Ltd.) was added in sequence at 0.11\. The addition rate is the solid content weight ratio to the dry weight of the mother Rude. 9. Dilute the slurry to 0.254, use part of it to measure DDT, and use the other part.
The paper was made using a hand paper machine made by Nople & Wood (-5,0), and 110 tl using a drum dryer.
:, Dry for 1.5 minutes to obtain handmade paper with tsubo 84±29/m" and 167±3.!?/m". Using this paper stock, the specific bursting strength and specific compressive strength were measured in the same manner as in Application Example 1. The results are shown in Table 6. From the same table, polyamide/epichlorohydrin condensation as cationic El Ill Table 6 Application Example 5 In order to see the effect of the anionic polyacrylamide copolymer of the present invention as a retention agent, a papermaking example using only sulfuric acid and dichloromethane is shown. . /4' Rude (NUKP: C3F=
To 370 ml) of a 2.5 width aqueous fraction, 0.44 of the anionic polyacrylamide copolymer was added, and then 2.0 width of sulfuric acid was added. The addition rate is the ratio of the solid content to the dry weight of the mother pulp. This slurry was diluted to 0.25%, DDT was measured, and the paper was made using a hand paper machine 6 made by Norple & Wood (pH 4.5), and the temperature was 110℃ using a drum dryer. ．．
Dry for 5 minutes, basis weight 81±2jj/m”+164±3
A hand-made paper of 117 m” was obtained. Application example 1 was carried out using this paper stock.
Specific bursting strength in the same manner as .

The specific compressive strength was measured. The results are shown in Table 7. The anionic polyacrylamide copolymer of the present invention exhibits excellent performance both on the wood surface and under conventional papermaking conditions such as using only sulfuric acid.

Table 7 Application Example 6 Although this is a special example of how an anionic paper strength enhancer is used, the effect of anionic polyacrylamide copolymer when polyamide/epichlorohydrin condensate is used in combination without using sulfate at all. shows. Noe Lua'
(LBKP: C3F=335 ml) to a 2.5-width aqueous dispersion, 0.25% or 0.5% of anionic polyacrylamide copolymer was added, and then Kaimen 55
Made of 7H (De42 Ri・) 1-Cures Hina), polyamide・
0.5 l of epichlorohydrin condensate) and 1' of No-Con W (Y' 4 Tsuk.) 1-Cures (alkyl sting/dimer sizing agent) were added to the 0.5 volume. The addition rate is the ratio of the solid charge to the dry weight. pH 7.0), then 1 in a drum dryer.
The paper was dried at 00° C. for 1.5 minutes to obtain handmade paper with a basis weight of 98±21/m 2 . The obtained paper stock was heated at 20°C and 654RI (
After conditioning the humidity for 24 hours under the following conditions, the "specific bursting strength" according to JISP-8112,
A water absorption test (Cobb test) was carried out. The results are shown in Table 8.

The anionic polyacrylamide copolymer of the present invention shows not only an excellent paper strength enhancement effect but also an excellent size retention effect.

No. 8 Representative Patent Attorney Katsutoshi Takahashi - Continued Amendment 11: (Voluntary) 6
December 611, 1985 Michibe Uga, Commissioner of the Patent Office 1 Indication of the case 3 Person making the amendment/Relationship with the case Patent applicant Address: 17-20 Dick, 31 Go, Mizuhashi, Chuo-ku, Tokyo 103 -Representative of Vercules Co., Ltd. Kawai -Line 4 Agent Address: 103 Chuo-ku, Tokyo [1-3-chome, Honbashi [17-20 Dai-1]
1 Ink Chemistry]: Gyo Co., Ltd. Telephone: Tokyo (03) 272-4511 (main representative)
- (8876) Patent Attorney Katsutoshi Takahashi □5 Contents of amendment in the "Detailed Description of the Invention" section of the specification to be amended (1) The statement on page 21, line 3 of the specification should be changed as follows: Correct.

Pan sulfate for the purpose of examining the effect of one single system

Claims (1)

[Claims] In anionic polyacrylamide paper strength enhancers,
It contains two or more types of α,β-unsaturated carboxylic acids or salts thereof as its anionic component, and these two or more types of α,β
- at least one of unsaturated carboxylic acids or salts thereof
A water-soluble copolymer for increasing paper strength, characterized in that the species is an α,β-unsaturated dicarboxylic acid or a salt thereof.