JP2002088685A - Method for increasing surface durability of paper - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a surface-treating polymer having high absorption into dried paper, but relatively low in an apparent viscosity even in the case of high molecular weight and high concentration of the solution. SOLUTION: The purpose of the present invention can be achieved by applying a primary amino group-containing (co)polymer on dried paper or impregnating the paper with the (co)polymer. The copolymer is obtained by polymerizing a monomer (or mixture) essentially containing an acrylic monomer having a primary amino group in the presence of a polyacrylamide polymer.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for enhancing paper strength, and more particularly to a method for drying a polymer of a monomer mixture comprising a specific monomer, a carboxyl group-containing acrylic monomer and acrylamide. The present invention relates to a paper-strengthening method characterized by applying or impregnating paper.

[0002]

2. Description of the Related Art Conventionally, as a surface strength improver for coating or impregnating a paper surface to improve printability,
Starch, polyvinyl alcohol or anionic polyacrylamide have been used. However, with the increase in printing speed, these surface treatment chemicals cannot always be said to be sufficient. There is a need for a surface treatment agent with higher functionality. Newspaper is the most demanded surface treatment agent. Newsprint paper has a very low degree of sizing, so that when applied or contained on the surface, a large part of the processing agent permeates into the paper.
The ratio of staying on the surface is low. As a method for improving this, studies have been made to increase the concentration at the time of applying the treating agent, or to increase the ratio of the treating agent being cationic or amphoteric to be adsorbed on the paper surface, but the most suitable one has not been completed yet. On the other hand, a paper strength enhancer to be added to the papermaking raw material before papermaking has both anionic and amphoteric properties. Among these, the amphoteric paper strength enhancer is conventionally a copolymer of acrylamide and N, N-dialkylamino (meth) acrylate or N, N-dialkylamino (meth) acrylamide and (meth) acrylic acid. It has been used regularly. Further, N, N-methylenebisacrylamide (JP-A-63-50597) is copolymerized therewith as a crosslinking agent, and more recently, N, N-dimethylacrylamide is copolymerized to give a high solution exhibiting unique solution properties. Paper strength enhancers comprising molecules have been developed (JP-A-5-140893, JP-A-5-287693, JP-A-5-272).
092 or JP-A-7-97790).
However, these N, N-dialkylamino (meth) acrylates or N, N-dialkylamino (meth) acrylamides are cationic monomers comprising a tertiary amino group, and therefore have a weak hydrogen bonding ability. In other words, the paper strength enhancing effect is caused by the hydrogen bonding strength between the hydroxyl group in the cellulose molecule and the side chain having hydrogen bonding strength in the paper strength enhancing agent. On the other hand, a primary amino group has two active hydrogens, and therefore has a strong hydrogen bonding force. Conventionally, paper strength enhancers made of monomers having a primary amino group as raw materials have not been studied except for vinylamine-based polymers due to the problem of monomers as raw materials.

In view of the molecular weight of a polymer applied as a paper strength enhancer, the effect as a paper strength enhancer is remarkable unless the molecular weight is a certain molecular weight or more, that is, about 100,000 or more. is not. Although the molecular weight must be more than a certain level,
As the molecular weight increases, the viscosity of the solution will inevitably increase, and the handling of the product and the dispersion in the papermaking raw material will worsen,
Undesirable points occur. Crosslinking can reduce the apparent solution viscosity to a certain extent, but it is not always easy to control the apparent viscosity of the product. for that reason,
The current situation is that there is a demand for paper strength enhancement that has a sufficient molecular weight, has an excellent paper strength enhancement effect, and exhibits physical properties of low apparent viscosity that is easy to handle. In some cases, the surface treatment agent for coating or impregnation is an important physical property in which the viscosity at the time of coating is important. Therefore, a polymer that exhibits a sufficient paper strength enhancing effect even when the viscosity is low is required.

[0004]

The problem to be solved by the present invention is to provide a polymer for surface treatment which has a strong adsorption power to paper after drying and has a relatively low apparent viscosity even when the molecular weight and the solution concentration are high. It is to develop.

[0005]

As a result of intensive studies to solve the above-mentioned problems, the following inventions have been reached. That is, the invention of claim 1 of the present invention is produced by polymerizing a monomer mixture containing a monomer represented by the following general formula (1) in the presence of a polyacrylamide-based polymer. This is a method for improving surface paper strength, characterized by applying or impregnating the dried primary amino group-containing polymer on dried paper.

Embedded image R is hydrogen or methyl, A is oxygen or NH, B
Is a C2-C3 alkylene group or an alkoxylene group,
X is an anion

According to a second aspect of the present invention, the monomer (mixture) comprises the monomer represented by the general formula (1) in an amount of 20 to 100 mol%.
2. The method for improving surface paper strength according to claim 1, wherein the amount of acrylamide is 0 to 80 mol%.

According to a third aspect of the present invention, the monomer mixture comprises 20 to 90 mol% of the monomer represented by the general formula (1) and the cationic monomer 10 represented by the following general formula (2). ~ 30
2. The method for improving surface paper strength according to claim 1, wherein the method comprises mol% and 0 to 70 mol% of acrylamide.

Embedded image R2 is hydrogen or methyl, R3 methyl or ethyl, R4 is methyl or ethyl, R5 is hydrogen, methyl or ethyl, A is oxygen or N
H and B are a C2 to C3 alkylene or alkoxylene group; X is an anion

According to a fourth aspect of the present invention, when a monomer mixture containing the monomer represented by the general formula (1) as an essential component in the presence of a polyacrylamide-based polymer is polymerized,
4. The method according to claim 1, wherein the surface paper strength is 2.0 to 6.0.

The invention according to claim 5 is that, when the number of moles of the monomer (mixture) is (A) and the number of moles of the repeating unit in the polyacrylamide polymer is (B), (A): (B) =
The ratio is 0.1: 1 to 1:10.
(4) A method for improving surface paper strength according to any one of (1) to (4).

According to a sixth aspect of the present invention, the polyacrylamide-based polymer comprises 60 to 100 mol% of acrylamide and 0 to 20 cationic monomers represented by the following general formula (2).
The surface paper strength according to claim 1, wherein the polymer is a polymer of a monomer mixture comprising mol% and 0 to 20 mol% of an anionic monomer represented by the following general formula (3). It is a way to make it.

Embedded image R6 is hydrogen, methyl or carboxymethyl, R7
Is hydrogen or carboxyl group

The invention of claim 7 is characterized in that the monomer represented by the general formula (1) is a salt of an organic acid or an inorganic acid of 2-aminoethyl methacrylate. It is a paper strength enhancing method according to any one of 1 to 5.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION In order to produce a primary amino group-containing cationic and / or amphoteric polymer used in the present invention,
First, an aqueous solution of a polyacrylamide-based polymer (hereinafter referred to as a trunk polymer) is prepared, and after adjusting the pH to 2.0 to 6.0, the cationic monomer represented by the general formula (1) is supplied. After that, the oxygen is removed from the reaction system by nitrogen replacement, and the polymerization is started by adding a radical polymerizable initiator, so that a cationic or amphoteric branched polymer is formed in the base polymer as the raw material. The concentration of the aqueous solution of the trunk polymer at the time of the reaction is generally 5 to 30% by weight, but the higher is preferable, but if it is too high, problems such as poor stirring and poor dispersibility of the monomer occur. So preferably 15
２５25% by weight. The total concentration of the stem polymer and the branch polymer after the reaction product is formed is 10 to 50% by weight, and varies depending on the degree of polymerization of the product. The reaction can be performed at a temperature of 20 to 100 ° C. Examples of the cationic monomer represented by the general formula (1) include 2-aminoethyl acrylate, 2-aminoethyl methacrylate, and 3-aminopropyl acrylate.
And salts of organic acids and inorganic acids such as tri- and 3-aminopropyl methacrylate. These monomers are usually stored in the form of inorganic or organic acid salts. It is common to add to the stem polymer solution and then adjust the pH.

Since the cationic monomer represented by the general formula (1) is an acrylic monomer, a good copolymerization reaction with various acrylic monomers is possible. Therefore, polymerization can be carried out in the presence of a copolymerizable monomer.
For example, non-ionic monomer (meth) acrylamide,
N, N-dimethylacrylamide, vinyl acetate, acrylonitrile, methyl acrylate, (meth) acrylic acid 2
-Hydroxyethyl, diacetone acrylamide, N-
Examples thereof include vinylpyrrolidone, N-vinylformamide, and N-vinylacetamide, and copolymerization with one or more nonionic monomers is also possible. An example of the most preferred nonionic monomer is acrylamide.

Further, it can be copolymerized with a monomer containing a tertiary amino group or a quaternary ammonium group. Examples of the tertiary amino-containing monomer include dimethylaminoethyl (meth) acrylate and dimethylaminopropyl (meth) acrylamide. Examples of the quaternary ammonium group-containing monomer include (meth) acryloyloxyethyltrimethylammonium chloride and (meth) acryloyl, which are quaternary compounds of the tertiary amino-containing monomer with methyl chloride or benzyl chloride. Oxy-2-hydroxypropyltrimethylammonium chloride, (meth) acryloylaminopropyltrimethylammonium chloride, (meth) acryloyloxyethyldimethylbenzylammonium chloride, (meth) acryloyloxy 2-hydroxypropyldimethylbenzylammonium chloride, ) Acryloylaminopropyldimethylbenzylammonium chloride and the like. Furthermore, dimethyldiallylammonium chloride can be copolymerized. Monomer mixture of these tertiary amino group or quaternary ammonium group-containing monomer, nonionic monomer and primary amino group-containing acrylic monomer which is an essential component in the polymer used in the present invention. Can also be used.

In the monomer mixture, the copolymer mol% of the primary amino group-containing monomer represented by the general formula (1) is defined as the primary amino group-containing monomer represented by the general formula (1) and acrylamide When used, it is 20 to 100 mol%: 0 to 80 mol%. When a primary amino group-containing monomer, a tertiary amino group or a quaternary ammonium salt-containing monomer represented by the general formula (1), or acrylamide is used, 10 to 90 mol%: 10 to 90 mol%, respectively. 30 mol%: 0 to 80 mol%. Since quaternary ammonium bases generally do not have hydrogen bonding, they do not contribute much to the paper strength enhancing effect. Therefore, when the content of the primary amino group-containing monomer is 50 mol% or less, the paper strength enhancing effect is undesirably reduced.

The polyacrylamide-based polymer used as a raw material can be nonionic, anionic, cationic or amphoteric. In the case of an anionic resin, the degree of anionization is 0 to 20 mol%, preferably 2 mol%.
１５15 mol%. As the anionic group, a carboxyl group is preferable. When cationic, the degree of cationization is 0 to 20 mol%, preferably 2 to 15 mol%.
It is. As the type of the cationic group, a tertiary amino group is more preferable. Further, in the case of amphoteric, the degree of cationization is 0 to 20 mol%, preferably 2 to 15 mol%,
The degree of anionization is 0 to 15 mol%, preferably 2 to 15 mol%. Also, the molecular weight of the polyacrylamide polymer is 10,000 to 1,000,000,
Preferably it is 50,000 to 1,000,000. If it is 10,000 or less, the degree of polymerization is too low, the molecular weight after graft polymerization does not become sufficient, and the paper strength enhancing effect is low. On the other hand, if it is 1,000,000 or more, the molecular weight of the raw material backbone polymer is too high, and the molecular weight after graft polymerization is too high, causing troubles during coating, or undesired phenomena such as sticking to the roll of the dryer after coating. Generate.

The molar ratio of the monomer (mixture) containing the primary amino group-containing monomer represented by the general formula (1) as an essential component and the repeating unit in the acrylamide polymer in the backbone polymer. Is 0.1: 1 to 10: 1, preferably 0.2: 1 to 10: 1, and more preferably 0.1 to 10: 1.
4: 1 to 8: 1. When the ratio is 0.1: 1 or less, the ratio of the backbone polymer becomes too large, and the characteristics of the graft polymer are hardly exhibited, and it is meaningless to produce. Also, 10:
When it is higher than 1, the ratio of the monomer (mixture) becomes too large, and the monomer is actually a homopolymer or a copolymer.

The radical polymerization initiator for initiating the polymerization can be polymerized by any of azo, peroxide and redox systems. Examples of oil-soluble azo initiators include:
2,2'-azobisisobutyronitrile, 1,1'-azobis (cyclohexanecarbonitrile), 2,2'-
Azobis (2-methylbutyronitrile), 2,2′-azobis (2-methylpropionate), 4,4-azobis (4-methoxy, 2,4-dimethyl) valeronitrile, etc. Dissolve in solvent and add. Examples of the water-soluble azo initiator include 2,2′-azobis (amidinopropane) dihydrochloride and 2,2′-azobis [2- (5-methyl-2-imidazolin-2-yl) propane] Hydrogen chloride, 4,4′-azobis (4-cyanovaleric acid) and the like. Examples of the redox system include a combination of ammonium or potassium peroxydisulfate with sodium sulfite, sodium hydrogen sulfite, trimethylamine, tetramethylethylenediamine, or the like. Further, examples of peroxides include ammonium peroxodisulfate, hydrogen peroxide, benzoyl peroxide, lauroyl peroxide, octanoyl peroxide, succinic peroxide, t-butylperoxy 2-ethylhexanoate and the like. Can be. Among these, particularly preferred initiators are 2,2′-azobis (amidinopropane) dihydrochloride, 2,2 ′, which is a water-soluble azo initiator.
-Azobis [2- (5-methyl-2-imidazoline-2
-Yl) propane].

The primary amino group-containing polymer used in the present invention can be used to polymerize a monomer mixture containing a primary amino group monomer to be co-present as an essential component. Ie, in the case of acrylamide, the carbon or (meth) bonded to the acid amide group
In the case of N, N-dialkylaminoalkyl acrylate, the carbon bonded to the ester bond and the hydrogen bonded to these carbons are extracted by the generated radical, and the cationic or amphoteric branched polymer is extracted from the site. Is generated. As a result, the acrylamide polymer is modified to exhibit different solution physical properties from the linear polymer, and the apparent viscosity is measured to be lower than that of the linear polymer having the same molecular weight. Since the initiator is used for the graft reaction, a larger amount of the initiator is required than a usual amount of the initiator. That is, it is 0.1 to 2.0% by weight, preferably 0.3 to 1.5% by weight, based on the weight of the monomer to be grafted. Usually, the polymerization conditions are appropriately determined depending on the monomers used and the molar percentage of copolymer, and the temperature is 20 to 100 ° C, preferably 40 to 100 ° C.
Perform at 90 ° C. The composition of the product after the grafting reaction is presumed to consist of a mixture of a grafted backbone polymer and a homopolymer or copolymer of a non-grafted monomer.

The paper product to which the primary amino group-containing polymer of the present invention is applied can be used for surface treatment of newsprint, general printing paper, packaging paper and the like. The coating can be performed by a known method. For example, application is performed using a size press, a film press, a gate coater, a blade coater, a calender, a bar coater, a knife coater, an air knife coater, or the like. be able to. The amount of coating is about 0.0 for newsprint.
2 to 0.5 g / m2, preferably 0.05 to 0.2 g / m2
It is. For high quality printing paper, approximately 0.1 to 0.5 g / m
2, preferably 0.1 to 0.3 g / m2. The concentration at the time of coating is from 0.5 to 15% by weight, but is preferably from 5 to 15 in order to increase the amount to be fixed on the surface. It is also possible to use a mixture with a conventional coating agent, for example, polyvinyl alcohol, coated starch, polyacrylamide-based polymer surface strength agent, and the like. Further, it may be used in combination with a sizing agent for application, that is, a surface sizing agent. The primary amino group-containing polymer of the present invention,
Since it is cationic, in the case of foreign ions, mixing can be performed by adjusting the pH at the time of mixing, so care must be taken in adjusting the pH at the time of mixing.

[0021]

The present invention will be described in more detail with reference to the following Examples and Comparative Examples. However, the present invention is not limited to the following Examples unless it exceeds the gist thereof.

[0022]

Synthesis Example 1 In a four-necked 500 ml separable flask equipped with a stirrer, a reflux condenser, a thermometer and a nitrogen inlet tube, 48.35 g of deionized water and a 70% aqueous solution of 2-aminoethyl methacrylate 71. 4 g and 75 g of amphoteric polyacrylamide (dimethylaminoethyl methacrylate)
Degree of cationization of 4.2 mol%, anionization degree of acrylic acid of 4.7 mol%, molecular weight of about 17, 40
0) was added (the molar ratio of the repeating unit to the monomer in the polyacrylamide-based polymer was 1: 0.363), dispersed, and completely dissolved for 1 hour. After dissolution, the pH of the mixed solution was adjusted to 3.2 with a 10% aqueous sulfuric acid solution. Thereafter, the mixture is externally heated by a water bath to reduce the temperature in the reaction vessel to 35.
The temperature was adjusted to ° C and nitrogen was introduced from a nitrogen introduction tube while stirring to remove dissolved oxygen. After 30 minutes, a 10% by weight solution of 2,2-azobisamidinopropane dihydrochloride3.
75 g (based on 0.5% by weight of monomer) was added to initiate polymerization. When the internal temperature rises to 70 ° C., the external heating is stopped and the reaction is continued while cooling at 70 to 75 ° C. for about 3 hours.
When the temperature began to decrease in 0 minutes, external heating was resumed at 50 ° C., and after 5 hours, 1.5 g of a 10% by weight solution of 2,2-azobisamidinopropane dihydrochloride (0.2% by weight of monomer) %), And the mixture was further reacted for 10 hours. After the reaction, the conversion of 2-aminoethyl methacrylate was measured by colloid titration. In addition, the weight average molecular weight was measured by a molecular weight measuring device (DLS-7000 manufactured by Otsuka Electronics Co., Ltd.) by a static light scattering method. This prototype is designated as S-1. This S
The solution viscosity of -1 was 16,700 mPa · s at a polymer concentration of 25% by weight (concentration of the backbone polymer and the charged 2-aminoethyl methacrylate). Table 1 shows the results.

[0023]

Synthetic Example 2 Except that the charged amount of 2-aminoethyl methacrylate was changed to 53.6 g of a 70% aqueous solution (the molar ratio of the repeating unit to the monomer in the polyacrylamide-based polymer was 1: 0 .133), and carried out in the same manner as in Example 1 to synthesize S-2. The solution viscosity of this S-1 was 25% by weight of polymer concentration.
(The concentration of the backbone polymer + the charged 2-aminoethyl methacrylate) was 10,200 mPa · s. Table 1 shows the results.

[0024]

Synthesis Example 3 73.35 g of deionized water and 70% aqueous solution of 2-aminoethyl methacrylate were placed in a four-necked 500 ml separable flask equipped with a stirrer, a reflux condenser, a thermometer and a nitrogen inlet tube. 4 g was added, and 75 g of anionic polyacrylamide (7.4 mol% of anionicity composed of acrylic acid, molecular weight of about 125,000) was added (molar ratio of repeating unit and monomer in polyacrylamide-based polymer). Was 1: 0.363), dispersed and completely dissolved for 1 hour. After dissolution, the pH of the mixed solution was adjusted to 3.5 with a 10% aqueous sulfuric acid solution. Thereafter, the mixture is heated from the outside with a water bath, the temperature in the reaction vessel is adjusted to 35 ° C., and nitrogen is introduced from a nitrogen introduction pipe while stirring to remove dissolved oxygen. After 30 minutes 3.75 g of a 10% by weight solution of 2,2-azobisamidinopropane dichloride
(Based on 0.5% by weight of monomer) was added to initiate polymerization.
When the internal temperature rises to 70 ° C, stop the external heating,
The reaction was continued while cooling at 70 to 75 ° C., and when the temperature began to decrease in about 30 minutes, external heating was restarted at 50 ° C.
After an hour, 1.5 g of a 10% by weight solution of 2,2-azobisamidinopropane dichloride (0.2% by weight of monomer)
It was added and reacted for another 10 hours. After the reaction, the conversion of 2-aminoethyl methacrylate was measured by colloid titration. In addition, the weight average molecular weight was measured by a molecular weight measuring device (DLS-7000 manufactured by Otsuka Electronics Co., Ltd.) by a static light scattering method. This prototype is designated as S-3. This S-3
The solution viscosity of 1 was 1 at a polymer concentration of 25% by weight (concentration of backbone polymer + charged 2-aminoethyl methacrylate).
4, and 100 mPa · s. Table 1 shows the results.

[0025]

Synthesis Example 4 S-4 was synthesized in the same manner as in Example 1, except that the raw material polyacrylamide-based polymer was changed to nonionic polyacrylamide. (The molar ratio of the repeating unit to the monomer in the polyacrylamide-based polymer is 1: 0.5.
44), The solution viscosity of S-4 is 25% by weight of polymer concentration.
(The concentration of the backbone polymer + the charged 2-aminoethyl methacrylate) was 16,000 mPa · s. Table 1 shows the results.

[0026]

Synthesis Example 5 98.05 g of deionized water and 70% aqueous solution of 2-aminoethyl methacrylate were placed in a four-necked 500 ml separable flask equipped with a stirrer, a reflux condenser, a thermometer, and a nitrogen inlet tube. 6 g and methacryloyloxyethyltrimethylammonium chloride 16.1 g were added, and 75 g of anionic polyacrylamide (degree of anionization: 7.6 mol%, molecular weight of about 100,000) was added (repeat units in the polyacrylamide-based polymer). And the molar ratio of monomer to monomer was 1: 0.562), and the mixture was dispersed and completely dissolved for 1 hour. After dissolution, the pH of the mixed solution was adjusted to 3.2 with a 10% aqueous sulfuric acid solution. Thereafter, the mixture is heated from the outside with a water bath, the temperature in the reaction vessel is adjusted to 35 ° C., and nitrogen is introduced from a nitrogen introduction pipe while stirring to remove dissolved oxygen. After 30 minutes, 3.75 g of a 10% by weight solution of 2,2-azobisamidinopropane dihydrochloride (0.5% by weight of monomer) was added to initiate polymerization. Internal temperature is 70
When the temperature rises to 0 ° C, the external heating is stopped, and
The reaction was continued while cooling at 0 ° C., and when the temperature began to drop in about 30 minutes, external heating was restarted at 50 ° C., and after 5 hours,
1.5 g of a 10% by weight solution of 2-azobisamidinopropane dihydrochloride (0.2% by weight based on monomer) was added, and the mixture was further reacted for 10 hours. After the reaction, the conversion of 2-aminoethyl methacrylate was measured by colloid titration. In addition, the weight average molecular weight was measured by a molecular weight measuring device (DLS-7000 manufactured by Otsuka Electronics Co., Ltd.) by a static light scattering method. This prototype is designated as S-5. The solution viscosity of this S-5 was 17,000 m at a polymer concentration of 25% by weight (concentration of trunk polymer + charged 2-aminoethyl methacrylate).
Pa · s. Table 1 shows the results.

[0027]

Synthesis Example 6 Using the amphoteric polyacrylamide of Synthesis Example 1 or 2 as the backbone polymer and 2-aminoethyl methacrylate as the monomer, the repeating unit and the monomer in the polyacrylamide-based backbone polymer were used. The polymerization was carried out at a molar ratio of 1: 2.0. This prototype is designated as S-6. This S
The solution viscosity of -6 was 21,000 mPa · s at a polymer concentration of 25% by weight (concentration of the backbone polymer and the charged 2-aminoethyl methacrylate). Table 1 shows the results.

[0028]

Comparative Synthesis Example 1 An amphoteric polyacrylamide polymer having the same number of cationic groups and anionic groups as in Example 1 was prepared by adding 19.6 mol% of 2-aminoethyl methacrylate and 6.1 mol of acrylic acid. % And acrylamide 74.
A copolymer consisting of 3 mol% was synthesized. This is designated as H-1. Table 2 shows the results.

[0029]

COMPARATIVE SYNTHESIS EXAMPLE 2 9.8 mol% of a polyacrylamide polymer 2-aminoethyl methacrylate having the same number of cationic groups and anionic groups as in Example 2,
A copolymer composed of 6.1 mol% of acrylic acid and 84.1 mol% of acrylamide was synthesized. This is designated as H-2. Table 2 shows the results.

[0030]

Comparative Synthesis Example 3 An amphoteric polyacrylamide polymer having the same number of primary amino groups, quaternary ammonium bases and anionic groups as in Example 5 was prepared in 8.9 mol% of 2-aminoethyl methacrylate, A copolymer comprising 6.4 mol% of yloxyethyltrimethylammonium chloride, 6.4 mol% of acrylic acid and 78.4 mol% of acrylamide was synthesized. This is designated as H-3. Table 2 shows the results.

[0031]

Comparative Synthesis Example 4 The amphoteric polyacrylamide polymer having the same number of cationic groups and anionic groups as in Example 2 was prepared by adding 9.8 mol% of dimethylaminoethyl methacrylate and 6.1 mol% of acrylic acid. And acrylamide 84.
A copolymer consisting of 1 mol% was synthesized. This is designated as H-4. Table 2 shows the results.

[0032]

Comparative Synthesis Example 5 Acrylic acid / acrylamide = 10.
A copolymer having a molar ratio of 6: 89.4 was synthesized. This is designated as H-5. Table 2 shows the results.

[0033]

Examples 1 to 6 A coating test was carried out using a medium-quality printing paper (60 g / m 2) which had not been subjected to surface treatment. S of Synthesis Examples 1 to 5
-1 to S-6 were adjusted to a concentration of 0.6% by weight, and the wire bar was
0.15g by (Wavestar PDS04)
/ M 2 and dried at 100 ° C for 5 minutes.
Thereafter, the humidity was adjusted at 20 ° C. and 65 RH for 24 hours, and the surface strength using an RI printability tester and the breaking length calculated from the tensile strength were measured. Table 3 shows the results.

[0034]

Comparative Examples 1 to 7 By the same operation as in Examples 1 to 5,
H-1 to H-5 of Comparative Synthesis Examples 1 to 5 were tested.
Further, samples prepared by mixing the samples of H-1 and H-4 and the amphoteric polyacrylamide used in Synthesis Example 1 at a ratio of 1: 1 were prepared (referred to as H-6 and H-7, respectively) and tested.
Table 3 shows the results.

[0035]

Examples 6 to 10 A coating test was carried out using uncoated paper of high quality printing paper (70 g / m @ 2). S-1 to S-6 of Synthesis Examples 1 to 5 were adjusted to a concentration of 0.85% by weight to prepare a wire.
0.2 by bar (PDS04, manufactured by Wavestar)
The coating was performed at 5 g / m 2 and dried at 100 ° C. for 5 minutes. Thereafter, the humidity was controlled at 20 ° C. and 65 RH for 24 hours.
The surface strength using a printability tester and the tear length calculated from the tensile strength were measured. Table 4 shows the results.

[0036]

Comparative Examples 8 to 14 By the same operation as in Examples 7 to 12, H-1 to H-5 and H-6 to 7 of Comparative Synthesis Examples 1 to 5 were performed.
Was tested. Table 4 shows the results.

[0037]

Examples 13 to 18 Coating tests were carried out using untreated paper of newsprint (43 g / m @ 2). S of Synthesis Examples 1 to 5
-1 to S-6 were adjusted to a concentration of 0.4% by weight and the wire bar
(PDS04, manufactured by Wavestar Co., Ltd.)
m2 and dried at 100 DEG C. for 5 minutes. Thereafter, the humidity was adjusted at 20 ° C. and 65 RH for 24 hours, and the surface strength using an RI printability tester and the breaking length calculated from the tensile strength were measured. Table 5 shows the results.

[0038]

Comparative Examples 15 to 21 By the same operation as in Examples 6 to 10, H-1 to H-5 and H-6 to H-6 of Comparative Synthesis Examples 1 to 5 were performed.
7 were tested. Table 5 shows the results.

[0039]

[Table 1] Molecular weight: unit is 10,000, 2EMA: 20% 2-aminoethyl methacrylate solution viscosity: unit: mPa · s

[0040]

[Table 2] 2EMA: 2-aminoethyl methacrylate DMC: methacryloyloxyethyltrimethylammonium chloride DMM: dimethylaminoethyl methacrylate AAC: acrylic acid, AAM: acrylamide 20% solution viscosity: unit: mPa · s, molecular weight: Unit is 10,000

[0041]

[Table 3] Breaking length: unit (Km) RI result: ○: good, Δ: somewhat good, ×: bad

[0042]

[Table 4] Breaking length: unit (Km) RI result: ○: good, Δ: somewhat good, ×: bad

[0043]

[Table 5] Breaking length: unit (Km) RI result: ○: good, Δ: somewhat good, ×: bad

Continued on the front page F term (reference) 4J011 AA05 BA04 BB01 DA04 PA69 PC02 4J026 AA50 BA20 BA25 BA27 BA29 BA30 BA32 BA39 BA40 BB01 BB03 BB04 DB12 DB14 DB15 DB16 DB25 DB32 FA04 GA01 GA02 GA06 GA08 4L055 AG70 AG72 BE08 BE10 FA13

Claims (7)

[Claims] 1. A primary amino group-containing polymer produced by polymerizing a monomer (mixture) containing a monomer represented by the following general formula (1) as an essential component in the presence of a polyacrylamide polymer. A method for improving surface paper strength, comprising applying or impregnating the coalesced paper on dried paper. Embedded image R is hydrogen or methyl, A is oxygen or NH, B
Is a C2-C3 alkylene group or an alkoxylene group,
X is an anion 2. The monomer (mixture) according to claim 1, wherein the monomer represented by the general formula (1) is 20 to 100 mol% and acrylamide is 0 to 80 mol%. To improve the surface strength of paper. 3. A monomer mixture comprising 20 to 90 mol% of a monomer represented by the general formula (1) and 10 to 30 mol% of a cationic monomer represented by the following general formula (2). The method for improving surface paper strength according to claim 1, comprising 0 to 70 mol% of acrylamide. Embedded image R2 is hydrogen or methyl, R3 methyl or ethyl, R4 is methyl or ethyl, R5 is hydrogen, methyl or ethyl, A is oxygen or N
H and B are a C2 to C3 alkylene or alkoxylene group; X is an anion 4. When a monomer mixture containing a monomer represented by the above formula (1) as an essential component is polymerized in the presence of a polyacrylamide polymer, the pH is 2.0 to 6.0. The method for improving surface paper strength according to claim 1, wherein: 5. When the number of moles of a monomer (mixture) is (A) and the number of moles of repeating units in a polyacrylamide polymer is (B), (A) :( B) = 0.1: 1-1: 1
5. The method for improving surface paper strength according to claim 1, wherein the value is zero. 6. A polyacrylamide polymer comprising 60 to 100 mol% of acrylamide, 0 to 20 mol% of a cationic monomer represented by the following general formula (2) and an anion represented by the following general formula (3) Monomer 0 to 20 mol%
The method for improving surface paper strength according to claim 1, wherein the polymer is a polymer of a monomer mixture consisting of: Embedded image R6 is hydrogen, methyl or carboxymethyl, R7
Is hydrogen or carboxyl group 7. A monomer represented by the general formula (1):
The paper strength enhancing method according to any one of claims 1 to 5, wherein the salt is a salt of an organic acid or an inorganic acid of 2-aminoethyl methacrylate.