JPH05163697A - Agent for improving surface strength of paper - Google Patents

Abstract

PURPOSE:To provide the subject agent containing a specified ratio of plural (meth)acrylamide polymers having mutually different molecular weight values or copolymers of a water-soluble vinyl monomer and (meth)acrylamide monomer and capable of improving surface abrasion, fuzzability, lubricity, etc., of a corrugated paper sheathing liner, etc. CONSTITUTION:(A) (Meth)acrylamide or a monomer mixture of (meth)acrylamide and a water soluble vinyl monomer (e.g. acrylic acid) is put in a reactor equipped with a heater. Potassium persulfate is added thereto in an aqueous medium and, after 5min, acidic sodium hyposulfite is added. Polymerization is carried out by heating the resultant mixture at 90 deg.C to obtain a polymer of 50000 to 1000000 average molecular weight. (B) The same monomer or monomer mixture is then polymerized in the presence of azobiscyanovalerate, ammonium persulfate and sodium bisulfite in an equeous medium under heating to obtain a polymer of 2000000 to 20000000 average molecular weight. Both the obtained polymers are mixed in a ratio of [(A):(B)=100:(0.1-300] on weight base, thus affording the objective agent having two different molecular weight distributions and capable of improving the surface strength of paper.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a paper surface strength improver. More specifically, a composition having two different molecular weight distributions of a (meth) acrylamide polymer or a copolymer of (meth) acrylamide and a water-soluble vinyl monomer in order to improve strength, particularly on the surface of paper. Is used as a surface strength improving resin, and relates to a paper surface strength improving agent and coated paper.

[0002]

2. Description of the Related Art Conventionally, the physical properties of the surface of corrugated cardboard exterior liners and other paperboards, high-quality papers, medium-quality papers, coated base papers, such as surface abrasion resistance, fluffiness, lubricity, gloss, and vessel pick, etc. Various measures have been taken to improve. In general, it is widely practiced to carry out calendar coating, impregnation with a size press, or spraying with a spray using a surface strength improver. There are many types of surface strength improvers processed by these coating methods, like the types of paper. Even if one resin that improves the surface abrasion resistance of paper is used, its usage is different for each company. That is, the difference in pulp formulation, the difference in paper machines,
There are differences in the required physical properties, such as differences in the types and amounts of chemicals used internally. That is, from those that can be slightly improved wearability, to those that must be hardly improved wearability, due to differences in the blending of pulp raw materials,
Sometimes the improvement of fluff is more important than the abrasion property.
In addition, the problem of the vessel pick may be synonymous with the wear property. As described above, of course, a wide variety of chemicals are required to modify the surface of various types of paper.
Under such circumstances, surface strength improvers that have been conventionally used include starch, oxidized starch, and modified products thereof, natural or semi-synthetic products such as carboxymethyl cellulose, and
There are polyvinyl alcohol and its derivatives and polyacrylamide and its modified products that exhibit excellent effects as a surface strength improver, and further urea resin, styrene-maleic acid copolymer, polyvinyl acetate, vinyl acetate-malenic acid copolymer, If you list latex type, emulsion type, etc. In addition, it is general to modify the surface of the paper with one or a combination of two or more of these. From the above, the surface strength improvers currently used in general paper companies are roughly classified into starch-based, polyvinyl alcohol-based,
It is a polyacrylamide type. Also, it is known that the variety is wide. The present applicant has previously proposed a paper surface modifier (Japanese Patent Laid-Open No. 64-006319) such as polyacrylamide or a modified polyacrylamide. However, even though these chemicals are quite effective in improving the surface strength, there are still no satisfactory chemicals in view of the current social situation in which more sophisticated products are required.

[0003]

DISCLOSURE OF THE INVENTION The inventors of the present invention have conducted extensive studies to solve these problems, and as a result, in the conventional starch-based, polyvinyl alcohol-based, and polyacrylamide-based surface strength improvers, the interfiber bond was changed. It is impossible to prevent picking of things such as vessels, soft cells and fine fiber plugs that do not have them from the paper surface, which causes paper dust and troubles during printing. Further, starch-based and polyvinyl alcohol-based have various problems such as workability, that is, a problem of dissolution process, foaming property when processed into paper, and viscosity problem during coating. The current situation is that it has not been released. The present inventors have been researching acrylamide-based surface strength improvers and commercializing the results for a long time, and have been highly evaluated by the market. Based on the accumulation of research over many years, as a result of repeated studies of surface strength improvers that impart even higher functionality, a (meth) acrylamide polymer or a (meth) acrylamide and water-soluble vinyl monomer copolymer, The inventors have found that a composition having two different molecular weight distributions exerts an excellent effect as a resin for improving the surface strength of paper, and arrived at the present invention.

[0004]

That is, the present invention is as follows. (a) A (meth) acrylamide polymer or a copolymer of (meth) acrylamide and a water-soluble vinyl monomer having an average molecular weight of 50,000 to 1,000,000 [A] and 2 million to 2,000.
A surface strength improving agent for paper, which comprises a composition consisting of two hundred thousand [B] and a compounding ratio of [A]: [B] = 100: 0.1 to 30 parts by weight. (b) The water-soluble vinyl monomer is selected from the group of ethylenically unsaturated carboxylic acids, ethylenic nitrile compounds, hydrophilic monomers, cationic vinyl monomers or dimer vinyl monomers. 1 or 2 or more of the above
(a) A surface strength improving agent for paper according to the above. (c) The hydrophilic monomer is acrylic acid-β-hydroxyethyl, methacrylic acid-β-hydroxyethyl, N-putoxymethyl acrylamide, glycidyl acrylate, glycidyl methacrylate. Surface strength improver. (d) cationic vinyl monomers are dimethylaminoethyl methacrylate, trimethylethyl methacrylate,
The paper surface strength improver according to (b) above, which is diethylaminoethyl methacrylate or trimethylaminoethyl methacrylate. (e) The paper surface strength improver according to (b) above, wherein the dimer vinyl monomers are methylenebisacrylamide and divinylbenzene. (f) A paper obtained by applying the surface strength improver for the paper according to any one of (a) to (e) above.

The method of the present invention will be described in detail below. The surface strength improver for paper in the present invention is a corrugated cardboard exterior liner or other paperboard, or upper, medium, surface abrasion of coated base paper, fluffing, slipperiness, gloss, Vessel Pick and others, paper A chemical that improves the physical properties required for surface modification, and contains a composition having two different molecular weight distributions, a (meth) acrylamide polymer and a copolymer of (meth) acrylamide and a water-soluble vinyl monomer. It becomes. Note that (meth) acrylamide is an abbreviation that indicates acrylamide, methacrylamide, or a mixture thereof (hereinafter,
Same). The water-soluble vinyl monomer used in the present invention is a vinyl monomer that is copolymerizable with (meth) acrylamide and has an excellent function as a paper modifier, and examples thereof include acrylic acid, methacrylic acid, and itacone. Ethylenically unsaturated carboxylic acids such as acids, maleic acid, fumaric acid and crotonic acid, ethylenic nitrile compounds such as acrylonitrile and methacrylonitrile, acrylic acid-β-hydroxyethyl, methacrylic acid-β-hydroxyethyl, N- Hydrophilic monomers such as butoxymethyl acrylamide, glycidyl acrylate, glycidyl methacrylate, cationic vinyl monomers such as dimethylaminoethyl methacrylate, trimethylethyl methacrylate, diethylaminoethyl methacrylate, trimethylaminoethyl methacrylate, One or more selected from the group of dimer vinyl monomers such as methylenebisacrylamide and divinylbenzene can be used. Among these vinyl monomers, those having a particularly good copolymerizability with acrylamide and further considering the performance and stability as a paper modifier, those preferably used are acrylic acid, methacrylic acid, acrylonitrile, methacrylonitrile and the like. is there. Of course, the components used are not limited to these exemplified compounds. In the present invention, the monomers exemplified above are referred to as water-soluble vinyl monomers. In the production of average molecular weight of 50,000 to 1,000,000 [A],
The monomers used for the (meth) acrylamide polymerization or the copolymerization of the (meth) acrylamide and the water-soluble vinyl monomer may be copolymerized in a pre-mixed state, or may be stepwise added and block-polymerized. Alternatively, graft polymerization may be performed. Further, it is preferable to carry out the copolymerization of these in an aqueous system.

The catalyst used for the polymerization of acrylamide or the copolymerization of acrylamide and a water-soluble vinyl monomer is a catalyst capable of effectively generating a radical in an aqueous system, that is, potassium persulfate, sodium persulfate or ammonium salt, persulfate. Radical polymerization is carried out using only a peroxide such as hydrogen sulfide, or a combination of the above-mentioned peroxide and a reducing agent such as acidic sodium sulfite or sodium thiosulfate,
That is, redox polymerization can be performed, and radical polymerization is performed using only the peroxide until the middle of the polymerization, and then the reducing agent, or a trialkylamine such as trimethylamine or triethylamine, or triethanolamine. Addition of trialkanolamines, dialkylamines such as dimethylamine and diethylamine, zircanolamines such as diethanolamine, monoalkylamines such as butylamine, monoalkanolamines such as monoethanolamine and the like to promote polymerization. You can also Among these catalysts, the catalysts particularly preferably used include peroxides such as potassium persulfate, sodium persulfate, ammonium persulfate, or salts thereof, which exhibit a catalytic effect rapidly at low temperature, and as a reducing agent. Preferable examples include acidic sodium sulfite and sodium thiosulfate. Redox is most preferably used in combination with these oxidizing agents and reducing agents. Also, one or more of these may be used,
The addition method may be one-step addition or multi-step addition. or,
It is not limited to the exemplified catalysts. The (meth) acrylamide polymer or the copolymer of (meth) acrylamide and a water-soluble vinyl monomer thus obtained according to the present invention is a caustic soda in order to obtain polymerizability (or copolymerizability) and long-term stability. , Potassium hydroxide, ammonia, and the above-mentioned amine compounds, or alkali or an acid such as sulfuric acid, nitric acid, formic acid, acetic acid or hydrochloric acid at the initiation of the polymerization or during the polymerization,
Alternatively, it can be used for pH control after completion of polymerization. Among these pH adjusting agents, preferred are acids, such as hydrochloric acid, sulfuric acid and nitric acid as inorganic acids, and formic acid and acetic acid as organic acids. In addition, examples of alkali include caustic soda, caustic potash, and ammonia.

Further, as a method for producing a (meth) acrylamide polymer having an average molecular weight of 2 to 20,000,000 [B] or a copolymer of (meth) acrylamide and a water-soluble vinyl monomer used in the present invention, conventional methods have been used. It is possible to take the method of. As a method for measuring the weight average molecular weight, there are a gel permeation method (hereinafter abbreviated as GPC method), a viscosity method and a light scattering method, and the GPC method is adopted in the present invention. As the GPC column, various aqueous gel columns can be used and can be determined from the calibration curve of the column. As a method for obtaining the surface strength improver of the present invention, the time when the (meth) acrylamide polymer having an average molecular weight of 2,000,000 to 20,000,000 or the copolymer [B] of (meth) acrylamide and a water-soluble vinyl monomer is added is When a (meth) acrylamide polymer having an average molecular weight of 50,000 to 1,000,000 or a copolymer [A] of (meth) acrylamide and a water-soluble vinyl monomer is produced, it may be added before the copolymerization or after the copolymerization. In any case, it does not matter even if it adds. The surface strength improver thus obtained suppresses picking of things such as vessels, parenchyma cells, and fiber plugments, which have no interfiber bond, from the paper surface than conventional surface strength improvers. It is possible to obtain a high surface strength effect. The reason for this has not been clarified clearly, but by using a composition having two different molecular weight distributions of a (meth) acrylamide polymer or a copolymer of (meth) acrylamide and a water-soluble vinyl monomer, The polymer yields a large amount on the surface of the paper, and because it has a high molecular weight, it exerts a strong adhesive force and surface strength, and the low-molecular polymer penetrates into the paper layer, and as a result, the paper strength is improved. It is presumed that such an excellent effect, which was not found in the conventional surface strength improvers, will be exhibited.

Here, the average molecular weight of the low molecular weight polymer is from 50,000 to
One million is the optimum molecular weight that can penetrate into the paper layer, and also the molecular weight that contributes to paper strength. On the other hand, the average molecular weight of the most suitable polyacrylamide type, which maximizes the yield of the paper surface and develops a strong adhesive force, is 2 to 20 million. It is for this reason that the average molecular weight of the low molecular weight polymer is 50,000 to 1,000,000 and the average molecular weight of the high molecular weight polymer is 2 to 20 million. Therefore, even if only a low molecular weight polymer, even if only a high molecular weight polymer, it is difficult to be a surface strength improver of the present invention, the composition of the present invention having both properties of penetration and strength, It is effective as a surface strength improver for paper. The preferred blending ratio of the polymers having different molecular weights in the present invention is preferably the following.
That is, the ratio of the low molecular weight polymer [A]: high molecular weight polymer [B] is parts by weight, and [A]: [B] = 100: 0.1 to 30, preferably [A]: [B] = 100: It is 0.5 to 20. The characteristics of each of the low molecular weight polymer and the high molecular weight polymer have already been described, but the above blending is preferable from the viewpoint of the balance between penetration and strength. That is, when the amount of the high molecular weight polymer exceeds 30 parts by weight in the system, the yield of the paper surface is remarkably improved, but since the penetration into the paper layer is lost, the paper strength effect becomes small, and conversely less than 0.1 parts by weight. In that case, the penetration into the paper layer is increased and only the paper strength is improved, and the effect as the surface strength improving agent aimed at by the present invention is reduced. The composition thus obtained is effective as a surface strength improver for paper, that is, two different molecular weight distributions of a (meth) acrylamide polymer or a copolymer of (meth) acrylamide and a water-soluble vinyl monomer. The paper surface strength improver having the property of being excellent in long-term stability, infinitely soluble in water, and supplied as a resin having remarkable workability. The paper surface strength improver of the present invention is generally processed by a paper manufacturing company with a size press, calender coating, spraying, etc., and at this time, the heating Kewer temperature is an important point, and in general, water is used. However, it is preferable that the temperature be 100 ° C. or higher to a temperature that does not adversely affect the paper, that is, 180 ° C. or so. The paper surface strength improving agent of the present invention is appropriately diluted with water at a paper manufacturing company, and processed into paper as necessary. The amount of addition varies depending on the degree of required physical properties of the paper at each company, and cannot be generally determined, but it is appropriate that the solid content is generally 0.1 to 5.0%.

Further, the paper surface strength improving agent of the present invention can be used in combination with various chemicals. For example, starch-based, carboxymethylcellulose-based, polyvinyl alcohol-based, acrylamide-based, etc., which have been conventionally used, and even when these chemicals are combined, they exhibit an excellent effect as a functional surface strength improver. The paper surface strength improver of the present invention is a surface abradable material such as corrugated cardboard exterior liner or other paperboard, or upper, medium quality paper, coated base paper, fluffing, slipperiness, gloss, Vesselpick or other paper surface modification. It is an extremely excellent drug that improves the physical properties required for quality.

[0010]

EXAMPLES The present invention will now be described with reference to Examples, Synthetic Examples and Comparative Examples in order to more specifically describe the present invention, but the present invention is not limited to these Examples. still,
Unless otherwise stated,% and parts are% by weight and parts by weight. (Production of Polymers [1] to [16]) Synthesis Example 1 477.7 g of water and 407.7 g of water were placed in a separable flask having a capacity of 1 liter equipped with a stirring rod with a variable motor equipped with a heating device (water bath), a cooling pipe and a thermometer. % Acrylamide 428.
5 g, 80% acrylic acid (hereinafter referred to as AA) 10.
2 g and subsequently 14.9 g of acrylonitrile (hereinafter abbreviated to AN) were charged and mixed and dissolved at room temperature. PH of this thing
Was measured to be PH 3.4. Next, set the flask and set the internal temperature to 30
When the temperature was raised to 0 ° C and the temperature became stable, potassium persulfate adjusted to 10% (hereinafter abbreviated as KPS) 34.0
After 5 minutes, 15.0 ml of acidic sodium sulfite (hereinafter abbreviated as SBS) adjusted to 10% was added. An exotherm started 1 minute after the addition of the acidic sodium sulfite and reached 90 ° C. in about 20 minutes, and the consistency began to appear with a slight yolk. After that, the primary polymerization was continued for 1 hour from the time when the temperature reached 90 ° C. with a heating device. Next, to carry out secondary polymerization 1
15.0 ml of 0% SBS was added and the polymerization was continued for 30 minutes. Next, cool this to 70 ° C, 20%
16.1 ml of NaOH was added and the pH was adjusted to 5.5. As a result of measuring the physical properties of the obtained polymer, the viscosity was 66.
It was 5 cp and the average molecular weight was 5,000. The weight obtained was 1000 g, which had a solid content of 20%.
This is designated as sample [1].

Synthetic Example 2 In the same apparatus as in Synthetic Example 1, 477.7 g of water, 428.5 g of 40% acrylamide, 10.2 g of 80% AA, followed by A
N14.9 g was charged and mixed and dissolved at room temperature. The pH of this product was measured and found to be 3.4. Next, the flask was set, the internal temperature was raised to 30 ° C. with the heating device which had been prepared, and when the temperature became stable, potassium persulfate adjusted to 10% (hereinafter abbreviated as KPS) 2
After adding 1.0 ml and further 5 minutes, 9.3 m of acidic sodium sulfite (hereinafter abbreviated as SBS) similarly adjusted to 10%.
1 was added. After the addition of acidic sodium sulfite, heat generation started in 1 minute and reached 90 ° C. in about 20 minutes, and the consistency began to appear while slightly yellowing. After that, the primary polymerization was continued for 1 hour from the time when the temperature reached 90 ° C. with a heating device. Next, in order to carry out secondary polymerization, 9.3 ml of 10% SBS was added, and the polymerization was continued for 30 minutes. Next, cool this to 70 ° C., 2
The pH was adjusted to 5.5 by adding 16.1 ml of 0% NaOH. As a result of measuring the physical properties of the obtained polymer, the viscosity was 7
It was 500 cp and the average molecular weight was 500,000. The weight obtained was 1000 g, which had a solid content of 20%. This is designated as sample [2]. Synthesis Example 3 477.7 g of water and 428.5 g of 40% acrylamide,
80% AA 10.2 g, AN 14.9 g
Polymerization was carried out in the same manner as in Example 5 of -51567 to obtain a polymer. When the intrinsic viscosity was measured by the same method as in Example 5 above, it was 4.45. As a result of obtaining the molecular weight by the following formula, it was 1,500,000. [Η] = 3.73 × 10 ⁻⁴ MW ^0.66 (where [η] is the intrinsic viscosity of polyacrylamide in a 1N sodium nitrate aqueous solution at a temperature of 30 ° C., and MW is the weight average molecular weight of polyacrylamide). The weight given is 1
000g, the solid content of this was 20%. This is designated as sample [3].

Synthesis Example 4 477.7 g of water and 428.5 g of 40% acrylamide,
An aqueous solution containing 80% AA (10.2 g) and AN (14.9 g) was prepared, and azobiscyanovaleric acid 1500 was prepared in the same manner as in Synthesis Example 3.
ppm, ammonium persulfate 37.5 ppm, and sodium bisulfite 15 ppm were added and polymerized to obtain a hydrous gel. The intrinsic viscosity of the hydrogel was measured in the same manner as in Example 3, and as a result, it was 15.55 and the average molecular weight was 10 million. The weight obtained was 1000 g, and the solid content thereof was 20%. This is designated as sample [4]. Synthesis Example 5 477.7 g of water and 428.5 g of 40% acrylamide,
An aqueous solution containing 80% AA (10.2 g) and AN (14.9 g) was prepared, and azobiscyanovaleric acid 1000 was prepared in the same manner as in Synthesis Example 3.
ppm, ammonium persulfate 25 ppm, and sodium bisulfite 10 ppm were added and polymerized to obtain a hydrogel. As a result of measuring the intrinsic viscosity of the hydrogel in the same manner as in Example 3, it was 28.47 and the average molecular weight was 25 million. The weight obtained was 1000 g, and the solid content thereof was 20%. This is designated as sample [5]. Synthesis Example 6 In the same apparatus as in Synthesis Example 1, 477.7 g of water, 428.5 g of 40% acrylamide, 10.2 g of 80% AA, AN
14.9 g was charged, 68.1 g of the polymer having a molecular weight of 10 million obtained in Synthesis Example 4 was added, and copolymerization was performed in the same manner as in Synthesis Example 1. The molecular weight of the obtained polymer was measured by the following method. The low molecular weight was measured by GPC using a column having an exclusion limit molecular weight of 3 × 10 ⁴ . As a result, the molecular weight of the polymer was 20,000. The high molecular weight was measured using a column having an exclusion limit molecular weight of 2 × 10 ⁸ and the molecular weight of the polymer was 12.5 million. The weight of the obtained product was 1068 g, and the solid content thereof was 20%. This is designated as sample [6].

Synthetic Example 7 As in Synthetic Example 3, 477.7 g of water, 428.5 g of 40% acrylamide, 10.2 g of 80% AA, AN1.
After charging 4.9 g, 68.1 g of the polymer having a molecular weight of 10,000,000 obtained in Synthesis Example 4 was added, and copolymerization was performed in the same manner as in Synthesis Example 3. The molecular weight of the obtained polymer was measured by the following method. The column was measured by the same GPC as in Synthesis Example 6 using an exclusion limit molecular weight of 2 × 10 ⁶ and an exclusion limit molecular weight of 2 × 10 ⁸ . As a result, the molecular weights were 1.8 million and 15 respectively.
It was, 000,000. The weight of the obtained product was 1068 g, and the solid content thereof was 20%. This is designated as sample [7]. Synthesis Example 8 477.7 g of water, 428.5 g of 40% acrylamide, 10.2 g of 80% AA and AN were placed in the same apparatus as in Synthesis Example 2.
14.9 g was charged and the molecular weight obtained in Synthesis Example 5 was 2500.
68.1 g of 10,000 polymer was added and copolymerized in the same manner as in Synthesis Example 2, and the molecular weight of the obtained polymer was measured by the following method. The low molecular weight was measured by GPC using a column having an exclusion limit molecular weight of 2 × 10 ⁶ . As a result, the molecular weight of the polymer was 700,000. The high molecular weight was measured using a column having an exclusion limit molecular weight of 2 × 10 ⁸ and the molecular weight of the polymer was 20 million or more. The weight obtained was 1068 g, and the solid content thereof was 20%. This is used as a sample [8]. Synthesis Example 9 68.1 g of the polymer having a molecular weight of 25 million obtained in Synthesis Example 5 was charged to 1000 g of the polymer having a molecular weight of 500,000 obtained in Synthesis Example 2 in the same apparatus as in Synthesis Example 1, and mixed and stirred at room temperature for 1 hour. 1
068 g of a mixture was obtained. The solid content of this product was 20%. This is a sample

[9].

Synthesis Example 10 In the same apparatus as in Synthesis Example 2, 477.7 g of water, 428.5 g of 40% acrylamide, 10.2 g of 80% AA, AN.
14.9 g was charged, 9.7 g of the polymer having a molecular weight of 10 million obtained in Synthesis Example 4 was added, and copolymerization was performed in the same manner as in Synthesis Example 2. The molecular weight of the obtained polymer was measured by the following method. The low molecular weight was measured by GPC using a column having an exclusion limit molecular weight of 2 × 10 ⁶ . As a result, the molecular weight of the polymer was 550,000. The high molecular weight was measured using a column having an exclusion limit molecular weight of 2 × 10 ⁸ and the molecular weight of the polymer was 10,000,000. The weight of the obtained product was 1009.7 g, and the solid content of the product was 20%. This is used as a sample [10]. Synthesis Example 11 The same apparatus as in Synthesis Example 2 was charged with 477.7 g of water, 428.5 g of 40% acrylamide and 80% AA. 10.2g, A
N 14.9 g was charged, and the molecular weight obtained in Synthesis Example 4 was 1,000.
Copolymerization was performed in the same manner as in Synthesis Example 2 by adding 97 g of a polymer. The molecular weight of the obtained polymer was measured by the following method. The low molecular weight was measured by GPC using a column having an exclusion limit molecular weight of 2 × 10 ⁶ . as a result,
The molecular weight of the polymer was 700,000. The measurement of high molecular weight is
As a result of measurement using a column having an exclusion limit molecular weight of 2 × 10 ⁸ , the molecular weight of the polymer was 13,000,000. The weight of the product obtained was 1097 g, and the solid content was 20%. This is designated as sample [11]. Synthesis Example 12 In the same apparatus as in Synthesis Example 2, 477.7 g of water, 428.5 g of 40% acrylamide, 10.2 g of 80% AA, AN
14.9 g was charged, 194 g of the polymer having a molecular weight of 10 million obtained in Synthesis Example 4 was added, and copolymerization was performed in the same manner as in Synthesis Example 2. The molecular weight of the obtained polymer was measured by the following method. The low molecular weight was measured by GPC using a column having an exclusion limit molecular weight of 2 × 10 ⁶ . As a result, the molecular weight of the polymer was 850,000. The high molecular weight was measured using a column having an exclusion limit molecular weight of 2 × 10 ⁸ and the molecular weight of the polymer was 16 million. The weight of the obtained product was 1194 g, and the solid content was 20%. This is designated as sample [12].

Synthetic Example 13 In the same apparatus as in Synthetic Example 1, 9.7 g of the polymer having a molecular weight of 500,000 obtained in Synthetic Example 4 and 9.7 g of the polymer having a molecular weight of 10 million obtained in Synthetic Example 4 were charged at room temperature to 1 hour mixing and stirring
009.7 g of a mixture was obtained. The solid content of this product is 20
%Met. This is designated as sample [13].

Synthesis Example 14 In the same apparatus as in Synthesis Example 1, 1000 g of the polymer having a molecular weight of 500,000 obtained in Synthesis Example 2 was charged with 97 g of the polymer having a molecular weight of 10 million obtained in Synthesis Example 4, and mixed at room temperature for 1 hour. Stir 10
97 g of mixture was obtained. The solid content of this product was 20%. This is designated as sample [14]. Synthesis Example 15 In the same apparatus as in Synthesis Example 1, 194 g of the polymer having a molecular weight of 10,000,000 obtained in Synthesis Example 4 was charged to 1000 g of the polymer having a molecular weight of 500,000 obtained in Synthesis Example 2, and mixed and stirred at room temperature for 1 hour.
194 g of a mixture was obtained. The solid content of this product was 20%. This is designated as sample [15]. Synthesis Example 16 89 g of water and 11 g of polyvinyl alcohol (manufactured by Nippon Gohsenol Co., Ltd.) were charged in the same apparatus as in Synthesis Example 1, and the mixture was stirred and dispersed while using a heating device to raise the internal temperature to 90 ° C. and to 30 ° C. at 30 ° C. It was dissolved. Cool this, 10
% Polyvinyl alcohol 100 g was obtained. This is designated as sample [16]. Sample [1] obtained by the above
[16] is summarized in Table-1.

[0017]

[Table 1]

Examples 1 to 4 K liner (manufactured by a certain company) basis weight of 150 g / m ² (A) and Jute liner (manufactured by a certain company) basis weight of 120 g / m ² (B) were cut into 40 cm length and 30 cm width. To prepare. This is paper (A),
It is called paper (B). Next, the sample [1 obtained in Synthesis Example 10
[0] was diluted with water so that the solid content was a) 1.0% and b) 2.0% on paper to obtain a diluted solution. This diluted solution is referred to as (coating solution [10] -a) and (coating solution [10] -b).
Then, on a flat glass plate, place paper (A) or paper (B)
Apply the top part of the cellophane tape with (the coating liquid [10]-
a) to wire lot # 10 and (Coating liquid [10]-
b) was applied once using a wire lot # 20, the resin adhesion amount was weighed, and then dried in a hot air dryer adjusted to 110 ° C. for 10 minutes to obtain a sample. In order of this, {Paper (A) [10]-
a}, {Paper (B) [10] -a}, {Paper (A) [1
0] -b}, {paper material (B) [10] -b}.
The paper material obtained in this way was placed in a constant temperature and humidity chamber (temperature: 20 ° C, humidity: 65 ° C).
%) Overnight, after that, in the same room, based on JIS-P-8129, a wax pick and a JIS-P-8136-based Gakshin type dyeing fastness tester (wear strength) were performed.

Examples 5 to 24 Diluents of samples [11] to [15] obtained in Synthesis Examples 11 to 15 on paper (A) and paper (B), respectively, according to the method performed in Example 1, that is, { Coating liquids [11] to [15] -a),
b)} was applied, and a test for surface strength was conducted in the same manner as in Example 1. Comparative Examples 1 to 40 According to the method performed in Example 1, samples [1] to [A] and (B) obtained in Synthesis Examples 1 to 9 and 16 respectively

[9]
And the dilution liquid of [16], that is, {coating liquid [1] to

[9] and [16] -a), b)} were applied, and a test for surface strength was conducted in the same manner as in Example 1. Comparative Examples 41 to 42 Paper (A) Paper (B) was replaced with water instead of the resin liquid, and a paper material was obtained and a test for surface strength was conducted according to the method of Example 1. This is called a blank. The test results performed in Examples 1 to 24 and Comparative Examples 1 to 42 are summarized in Table 2.

[0020]

[Table 2]

[0021]

[Table 3]

[0022]

The surface strength improving agent (Example) of the present invention is
It is clear from Table 2 that the surface strength improver is extremely excellent in modifying the surface as compared with conventional chemicals. PAM of Comparative Examples 1-36, Comparative Examples 37-40
In comparison with the PVA of No. 1 and the blanks of Comparative Examples 41 to 42, excellent results are obtained as a surface strength improver. Further, in the comparison between the conventional PAM and PVA shown in Comparative Examples 5 to 8, PVA is slightly superior. The compositions shown in Examples 1 to 24 of the paper surface strength improver of the present invention are all PAM and PV.
Better than A.

Front Page Continuation (72) Inventor Toshiki Oyanagi 7-1-1 1-1 Hikoshimasako-cho, Shimonoseki City, Yamaguchi Prefecture Mitsui Toatsu Chemical Co., Ltd.

Claims (6)

[Claims] 1. A (meth) acrylamide polymer or a copolymer of (meth) acrylamide and a water-soluble vinyl monomer having an average molecular weight of 50,000 to 1,000,000 [A].
Surface strength of paper containing a composition consisting of 2 to 20 million [B] two polymers and having a compounding ratio of [A]: [B] = 100: 0.1 to 30 parts by weight Improver. 2. The water-soluble vinyl monomer is selected from the group of ethylenically unsaturated carboxylic acids, ethylene nitrile compounds, hydrophilic monomers, cationic vinyl monomers or dimer vinyl monomers. The surface strength improver for paper according to claim 1, which is one or two or more types thereof. 3. The hydrophilic monomer is acrylic acid-β-hydroxyethyl, methacrylic acid-β-hydroxyethyl, N-putoxymethylacrylamide, glycidyl acrylate, glycidyl methacrylate. Surface strength improver for paper. 4. The surface strength improver for paper according to claim 2, wherein the cationic vinyl monomers are dimethylaminoethyl methacrylate, trimethylethyl methacrylate, diethylaminoethyl methacrylate and trimethylaminoethyl methacrylate. 5. The paper surface strength improver according to claim 2, wherein the dimer vinyl monomers are methylenebisacrylamide and divinylbenzene. 6. A paper obtained by coating the surface strength improver of any one of claims 1 to 5.