JP7277884B2 - Method for manufacturing paper strength agent - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for producing a paper strength agent used in the production of paper.

Polyacrylamide-based paper strength agents have hitherto been known as paper strength agents for imparting strength to paper. Polyacrylamide-based paper strength agents are classified into anionic type, cationic type, and amphoteric type according to ionicity. At present, amphoteric type paper strength agents are the mainstream from the standpoint of performance. Amphoteric polyacrylamide paper strength agents are composed of amphoteric acrylamide water-soluble polymers obtained by copolymerizing acrylamide with various polymerizable components such as cationic monomers and anionic monomers (Patent Document 1). The amphoteric acrylamide-based water-soluble polymer forms a polyion complex. Polyion complexes are formed by electrostatic interactions between cationic and anionic groups. Amphoteric acrylamide-based water-soluble polymers are known to exhibit paper strength enhancing effects by forming polyion complexes.

In recent years, due to the progress of recycling of used paper and the closed system, fine fibers and dissolved electrolyte substances accumulate in the papermaking system, and the electrical conductivity of the papermaking system tends to increase. For this reason, amphoteric type paper strength agents in particular are in a situation where the formation of ion complexes is inhibited and sufficient effects cannot be exhibited.

On the other hand, it is known that water-soluble polymers having hydrophobic groups in the molecule form aggregates in water (Non-Patent Document 1). Since the hydrophobic association is formed by hydrophobic interaction, the formation is not inhibited by the presence of dissolved electrolytes.

A paper strength agent containing a copolymer obtained by copolymerizing a cationic monomer, an anionic monomer, a crosslinkable vinyl monomer, a hydrophobic vinyl monomer and (meth)acrylamide is known (Patent Document 2). . Hydrophobic monomers in the art are vinyl-based monomers having low solubility in water and poor solubility in water. Mixtures of more than one species are mentioned. These monomers are added to water and polymerized by adding a polymerization initiator to obtain the desired polymer. However, a poorly water-soluble monomer forms droplets of a hydrophobic monomer when added to water and stirred, and there is a problem that uniform copolymerization with other water-soluble monomers is difficult to occur.

A copolymer having a solubility parameter of 20.5 (MPa) ^1/2 or less and having structural units derived from one or more nonionic monomers and structural units derived from one or more anionic or cationic monomers ( A paper quality improver containing A) and a surfactant (B) in the range of (A)/(B)=99/1 to 1/99 (weight ratio) is disclosed (Patent Document 3). The paper quality improver in this technology is obtained by preliminarily obtaining a copolymer and then mixing it with a surfactant.

JP 2012-251252 A JP-A-5-156597 JP-A-2004-52216 Kobunshi Vol. 46, March (1997), pp. 128-131

An object of the present invention is to solve the problems of amphoteric type paper strength agents that are generally used, and to provide a new type of paper strength agent that is less susceptible to ionic contaminants and has an excellent paper strength enhancing effect. It is in. Another object of the present invention is to improve the performance of a paper strength agent obtained by copolymerizing a hydrophobic monomer and a hydrophilic monomer.

As a result of extensive studies, the present inventors have found that a monomer containing a hydrophobic monomer, (meth)acrylamide, and a cationic monomer as essential components and containing no reactive surfactant is polymerized in the presence of a surfactant. It was found that the polymer obtained by

ADVANTAGE OF THE INVENTION According to this invention, the paper strength agent which has the outstanding paper strengthening effect can be obtained.

The present invention will be described in detail below.

According to the present invention, a hydrophobic monomer, (meth)acrylamide, and a cationic monomer are essential components, and by polymerizing a monomer containing no reactive surfactant in the presence of a surfactant, excellent A polymer having a paper strength enhancing effect is obtained. Polymerization can be carried out by conventionally known methods such as aqueous solution polymerization, suspension polymerization, and dispersion polymerization in salt water. For example, a monomer mixture, water, a surfactant, and a radical polymerization initiator are added to a predetermined reaction vessel, and stirred and heated under an inert gas atmosphere such as nitrogen gas to obtain the desired polymer. can be done.

Hydrophobic monomers include butyl (meth)acrylate, octyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, dodecyl (meth)acrylate, octadecyl (meth)acrylate and styrene. It is also possible to combine two or more of these. The hydrophobic monomer content is preferably 0.05 to 15% by mass, more preferably 0.1 to 10% by mass, based on the total monomers. If the amount of the hydrophobic monomer is too small, the formation of hydrophobic aggregates will be insufficient and the effect of increasing paper strength will be reduced. If the amount of the hydrophobic monomer is large, the amount of acrylamide will be small, and the bonding strength due to hydrogen bonding with pulp will be reduced, resulting in a reduction in the effect of increasing paper strength.

Cationic monomers include salts of inorganic acids or organic acids such as dimethylaminoethyl (meth)acrylate, diethylaminoethyl (meth)acrylate, dimethylaminopropyl (meth)acrylamide, diethylaminopropyl (meth)acrylamide, or these A monomer having a quaternary ammonium salt obtained by reacting a tertiary amino group-containing monomer with a quaternizing agent such as methyl chloride, benzyl chloride, dimethyl sulfate, epichlorohydrin, and the like. It is also possible to combine two or more of these. The cationic monomer content is preferably 3 to 30% by mass, more preferably 5 to 25% by mass, based on the total monomers. If the amount of the cationic monomer is too small, the absorbability to pulp will decrease, and the effect of increasing paper strength will decrease. On the other hand, if the amount of the cationic monomer is too large, the amount of acrylamide will be too small, and the bonding strength due to hydrogen bonding with pulp will decrease, resulting in a decrease in the effect of increasing paper strength.

The polymer related to the paper strength agent of the present invention can further contain nonionic monomers other than acrylamide, anionic monomers, crosslinkable monomers, etc., as polymerization components. The total amount of these is preferably 20% by mass or less based on the total amount of monomers. Incidentally, the polymer related to the paper strength agent of the present invention does not contain reactive surface activity as a polymer component. Here, the reactive surfactant is a monomer having a substituent having a radically polymerizable ethylenic double bond in one molecule and functioning as a surfactant.

Nonionic monomers other than acrylamide include dimethylacrylamide, vinylformamide, hydroxyethyl (meth)acrylate and the like. It is also possible to combine two or more of these.

Examples of anionic monomers include monocarboxylic acid monomers such as (meth)acrylic acid and crotonic acid; dicarboxylic acid monomers such as maleic acid and itaconic acid; Examples include organic sulfonic acid monomers, alkali metal salts such as sodium salts thereof, and ammonium salts thereof. It is also possible to combine two or more of these.

Examples of crosslinkable monomers include methylenebisacrylamide, ethylene glycol di(meth)acrylate, N-methylolacrylamide, triallyl isocyanate, divinylbenzene and the like. It is also possible to combine two or more of these. The amount to be added is preferably 1% by mass or less based on the total amount of monomers.

Surfactants used in polymerization are substances having a hydrophilic group and a hydrophobic group in the molecule. Ethylene sorbitan fatty acid ester, polyoxyethylene alkyl ether such as polyoxyethylene cetyl ether, polyoxyethylene oleyl ether, polyoxyethylene lauryl ether, sorbitan fatty acid ester such as sorbitan monooleate, sorbitan monostearate, sodium dodecyl sulfate, naphthalene Polyoxyethylene higher alcohol ethers such as sulfonate-formalin condensate, pentaoxyethylene oleyl alcohol ether and the like. It is also possible to combine two or more of these. Polymerization in water in the presence of a surfactant has the effect of finely dispersing the monomers and promotes copolymerization. If the amount of the surfactant is too small, the effect of finely dispersing the monomers will be small, and if it is too large, foaming will occur during dissolution and use. The amount of the surfactant added is 0.01% to 5% by mass, preferably 0.05% to 3% by mass, more preferably 0.1% to 1% by mass, based on the total monomers. is.

It is preferred to use a chain transfer agent in the present invention. Chain transfer agents include alkylmercaptans, thioglycolic acid and its esters, isopropyl alcohol, allyl alcohol, allylamine, sodium diphosphite and the like. Monomers such as methallylsulfonates such as sodium methallylsulfonate, potassium methallylsulfonate, and ammonium methallylsulfonate are also included.

Examples of the polymerization initiator include persulfates such as sodium persulfate, potassium persulfate and ammonium persulfate, and peroxides such as hydrogen peroxide and benzoyl peroxide. Although these can be used alone, they can also be used as redox polymerization initiators in combination with reducing agents such as sulfites and hydrogen sulfites. 2,2′-azobis[2-(5-methyl-imidazolin-2-yl)propane]dihydrochloride, 2,2′-azobis[2-(2-imidazolin-2-yl)propane]dihydrochloride, Azo polymerization initiators such as 2,2'-azobis-2-amidinopropane dihydrochloride can also be used. The amount of the polymerization initiator is 0.05% to 2% by weight, preferably 0.1% to 1% by weight, based on the total monomers.

The polymerization reaction is usually carried out at a temperature of 30° C. to 100° C. for 0.5 hour to 20 hours. The resulting polymer concentration is usually 5 to 50% by weight.

The resulting polymer preferably has a viscosity of 5 to 50 mPa·s as a 1 mass % aqueous solution of the polymer. The viscosity was measured with a Brookfield viscometer at 60 rpm and 25°C. If the viscosity is less than this, the effect of increasing paper strength will be insufficient. On the other hand, if the viscosity is higher than this, the solubility is lowered and the handling becomes difficult. As the B-type viscometer, general-purpose products such as B8M type and TVB-10M type manufactured by Toki Sangyo Co., Ltd. are appropriately used. If the viscosity is 100 mPa·s or less, use the No. 1 rotor.

The types of paper that use the paper strength agent in the present invention include newsprint, high-quality printing paper, medium-quality printing paper, gravure printing paper, PPC paper, base paper for coating, fine coated paper, packaging paper, liner and corrugating medium. Base paper, such as cardboard. As for the place of addition, it is added in the pulp slurry in the papermaking process or in the wet end portion such as on the wet paper. The addition rate is 0.05 to 10% by mass, preferably 0.1 to 5% by mass, based on the dry solid content of the pulp. It can also be used in combination with other papermaking chemicals such as paper strength agents, sizing agents, aluminum sulfate, coagulants, retention aids and drainage improvers.

EXAMPLES The present invention will be described in more detail below with reference to examples, but the present invention is not limited to the following examples as long as the gist thereof is not exceeded. The viscosity was measured at 60 rpm and 25° C. using a Brookfield viscometer.

(Example 1)
In a 500 mL four-necked flask, 0.5 g dodecyl acrylate, 7.5 g dimethylaminoethyl methacrylate, 5.0 g 35% by weight hydrochloric acid, 84.3 g 50% by weight acrylamide, 153.0 g demineralized water, 0.05 g sodium dodecyl sulfate , 0.30 g of sodium methallylsulfonate, and 0.1 g of 2,2'-azobis[2-(2-imidazolin-2-yl)propane] dihydrochloride (VA-044 manufactured by Wako Pure Chemical Industries, Ltd.) were charged at 200 rpm. Nitrogen gas was passed through while stirring. After 30 minutes, the temperature was raised to 50° C. and held for 3 hours. After that, it was kept at 70° C. for 2 hours. After that, it was cooled to obtain an aqueous polymer solution. The viscosity of the resulting 1% by mass aqueous solution of the polymer was 25.5 mPa·s. The results are shown in Table 1.

(Example 2)
In a 500 mL four-necked flask, 1.0 g of dodecyl acrylate, 7.5 g of dimethylaminoethyl methacrylate, 5.0 g of 35% by weight hydrochloric acid, 83.3 g of 50% by weight acrylamide, 153.5 g of demineralized water, naphthalene sulfonate formalin condensate (WS-100 manufactured by Senka), 0.30 g of sodium methallyl sulfonate, and 0.1 g of VA-044 (manufactured by Wako Pure Chemical Industries) were charged, and nitrogen gas was passed while stirring at 200 rpm. After 30 minutes, the temperature was raised to 50° C. and held for 3 hours. After that, it was kept at 70° C. for 2 hours. After that, it was cooled to obtain an aqueous polymer solution. The viscosity of the resulting 1% by mass aqueous solution of the polymer was 17.5 mPa·s. The results are shown in Table 1.

(Example 3)
1.0 g of dodecyl acrylate, 7.5 g of dimethylaminoethyl methacrylate, 5.0 g of 35% by weight hydrochloric acid, 83.0 g of 50% by weight acrylamide, 153.5 g of demineralized water, polyoxyalkylene alkyl ether ( 0.1 g of CL-100 (manufactured by Sanyo Chemical Industries), 0.30 g of sodium methallylsulfonate, and 0.1 g of VA-044 (manufactured by Wako Pure Chemical Industries) were charged, and nitrogen gas was passed through while stirring at 200 rpm. After 30 minutes, the temperature was raised to 50° C. and held for 3 hours. After that, it was kept at 70° C. for 2 hours. After that, it was cooled to obtain an aqueous polymer solution. The viscosity of the resulting 1% by mass aqueous solution of the polymer was 24.0 mPa·s. The results are shown in Table 1.

(Example 4)
In a 500 mL four-necked flask, 1.0 g dodecyl acrylate, 1.0 g styrene, 7.5 g dimethylaminoethyl methacrylate, 5.0 g 35% by weight hydrochloric acid, 81.0 g 50% by weight acrylamide, 154.5 g demineralized water, poly 0.10 g of oxyalkylene alkyl ether (CL-100 manufactured by Sanyo Chemical Industries), 0.30 g of sodium methallyl sulfonate, and 0.1 g of VA-044 (manufactured by Wako Pure Chemical Industries) were charged and nitrogen gas was passed through while stirring at 200 rpm. . After 30 minutes, the temperature was raised to 50° C. and held for 3 hours. After that, it was kept at 70° C. for 2 hours. After that, it was cooled to obtain an aqueous polymer solution. The viscosity of the resulting 1% by mass aqueous solution of the polymer was 28.0 mPa·s. The results are shown in Table 1.

(Example 5)
1.0 g of dodecyl acrylate, 1.0 g of 2-ethylhexyl acrylate, 7.5 g of dimethylaminoethyl methacrylate, 5.0 g of 35% by weight hydrochloric acid, 81.2 g of 50% by weight acrylamide, and demineralized water in a 500 mL four-necked flask. 154.5 g, polyoxyalkylene alkyl ether (CL-100 manufactured by Sanyo Chemical Industries) 0.10 g, sodium methallyl sulfonate 0.30 g, VA-044 (manufactured by Wako Pure Chemical Industries) 0.1 g were charged and stirred at 200 rpm. Nitrogen gas was passed through. After 30 minutes, the temperature was raised to 50° C. and held for 3 hours. After that, it was kept at 70° C. for 2 hours. After that, it was cooled to obtain an aqueous polymer solution. The viscosity of the resulting 1% by mass aqueous solution of the polymer was 18.0 mPa·s. The results are shown in Table 1.

(Example 6)
1.0 g of dodecyl acrylate, 1.0 g of 2-ethylhexyl acrylate, 7.5 g of dimethylaminoethyl methacrylate, 5.0 g of 35% by weight hydrochloric acid, 81.2 g of 50% by weight acrylamide, and demineralized water in a 500 mL four-necked flask. 154.5 g, polyoxyalkylene alkyl ether (CL-100 manufactured by Sanyo Chemical Industries) 0.50 g, sodium methallyl sulfonate 0.30 g, VA-044 (manufactured by Wako Pure Chemical Industries) 0.1 g were charged and stirred at 200 rpm. Nitrogen gas was passed through. After 30 minutes, the temperature was raised to 50° C. and held for 3 hours. After that, it was kept at 70° C. for 2 hours. After that, it was cooled to obtain an aqueous polymer solution. The viscosity of the resulting 1% by mass aqueous solution of the polymer was 16.0 mPa·s. The results are shown in Table 1.

(Example 7)
In a 500 mL four-necked flask, 1.0 g dodecyl acrylate, 7.5 g dimethylaminoethyl methacrylate, 5.0 g 35 wt% hydrochloric acid, 83.1 g 50 wt% acrylamide, 1.3 g 80 wt% acrylic acid, 153 g demineralized water. 5 g, polyoxyalkylene alkyl ether (CL-100 manufactured by Sanyo Chemical Industries) 0.10 g, sodium methallyl sulfonate 0.30 g, and VA-044 (manufactured by Wako Pure Chemical Industries) 0.1 g were charged and stirred at 200 rpm. Nitrogen gas was passed through. After 30 minutes, the temperature was raised to 50° C. and held for 3 hours. After that, it was kept at 70° C. for 2 hours. After that, it was cooled to obtain an aqueous polymer solution. The viscosity of the resulting 1% by mass aqueous solution of the polymer was 16.0 mPa·s. The results are shown in Table 1.

(Example 8)
0.2 g of dodecyl acrylate, 7.5 g of dimethylaminoethyl methacrylate, 5.0 g of 35% by weight hydrochloric acid, 84.5 g of 50% by weight acrylamide, 152.8 g of demineralized water, polyoxyalkylene alkyl ether ( 0.10 g of CL-100 (manufactured by Sanyo Chemical Industries), 0.30 g of sodium methallylsulfonate, and 0.1 g of VA-044 (manufactured by Wako Pure Chemical Industries) were charged, and nitrogen gas was passed through the mixture while stirring at 200 rpm. After 30 minutes, the temperature was raised to 50° C. and held for 3 hours. After that, it was kept at 70° C. for 2 hours. After that, it was cooled to obtain an aqueous polymer solution. The viscosity of the resulting 1% by mass aqueous solution of the polymer was 19.5 mPa·s. The results are shown in Table 1.

(Example 9)
In a 500 mL four-necked flask, 0.05 g of octadecyl methacrylate, 7.5 g of dimethylaminoethyl methacrylate, 5.0 g of 35% by weight hydrochloric acid, 84.9 g of 50% by weight acrylamide, 152.6 g of demineralized water, polyoxyalkylene alkyl ether 0.10 g of CL-100 (manufactured by Sanyo Chemical Industries), 0.30 g of sodium methallyl sulfonate and 0.1 g of VA-044 (manufactured by Wako Pure Chemical Industries) were charged, and nitrogen gas was passed while stirring at 200 rpm. After 30 minutes, the temperature was raised to 50° C. and held for 3 hours. After that, it was kept at 70° C. for 2 hours. After that, it was cooled to obtain an aqueous polymer solution. The viscosity of the resulting 1% by mass aqueous solution of the polymer was 22.5 mPa·s. The results are shown in Table 1.

(Example 10)
1.0 g dodecyl acrylate, 7.5 g dimethylaminoethyl methacrylate, 5.0 g 35% by weight hydrochloric acid, 83.1 g 50% by weight acrylamide, 0.051 g methylenebisacrylamide, 153.5 g demineralized water in a 500 mL four-necked flask. , Polyoxyalkylene alkyl ether (CL-100 manufactured by Sanyo Chemical Industries) 0.10 g, sodium methallyl sulfonate 0.75 g, VA-044 (manufactured by Wako Pure Chemical Industries) 0.1 g were charged and nitrogen gas was added while stirring at 200 rpm. through. After 30 minutes, the temperature was raised to 50° C. and held for 3 hours. After that, it was kept at 70° C. for 2 hours. After that, it was cooled to obtain an aqueous polymer solution. The viscosity of the resulting 1% by mass aqueous solution of the polymer was 30.5 mPa·s. The results are shown in Table 1.

(Example 11)
In a 500 mL four-necked flask, 5.0 g of butyl acrylate, 7.5 g of dimethylaminoethyl methacrylate, 5.0 g of 35% by weight hydrochloric acid, 75.1 g of 50% by weight acrylamide, 157.5 g of demineralized water, polyoxyalkylene alkyl ether ( 0.10 g of CL-100 (manufactured by Sanyo Chemical Industries), 0.30 g of sodium methallylsulfonate, and 0.1 g of VA-044 (manufactured by Wako Pure Chemical Industries) were charged, and nitrogen gas was passed through the mixture while stirring at 200 rpm. After 30 minutes, the temperature was raised to 50° C. and held for 3 hours. After that, it was kept at 70° C. for 2 hours. After that, it was cooled to obtain an aqueous polymer solution. The viscosity of the resulting 1% by mass aqueous solution of the polymer was 26.0 mPa·s. The results are shown in Table 1.

(Example 12)
In a 500 mL four-necked flask, 1.0 g dodecyl acrylate, 1.0 g styrene, 7.5 g dimethylaminoethyl methacrylate, 5.0 g 35% by weight hydrochloric acid, 81.0 g 50% by weight acrylamide, 154.5 g demineralized water, poly 0.10 g of oxyethylene sorbitan trioleate (TW-85 manufactured by Wako Pure Chemical Industries), 0.30 g of sodium methallyl sulfonate, and 0.1 g of VA-044 (manufactured by Wako Pure Chemical Industries) were charged and nitrogen gas was introduced while stirring at 200 rpm. through. After 30 minutes, the temperature was raised to 50° C. and held for 3 hours. After that, it was kept at 70° C. for 2 hours. After that, it was cooled to obtain an aqueous polymer solution. The viscosity of the resulting 1% by mass aqueous solution of the polymer was 17.5 mPa·s. The results are shown in Table 1.

(Comparative example 1)
7.5 g of dimethylaminoethyl methacrylate, 5.0 g of 35% by mass hydrochloric acid, 85.0 g of 50% by mass acrylamide, 152.5 g of demineralized water, 0.25 g of sodium methallylsulfonate, and VA-044 were placed in a 500 mL four-necked flask. (manufactured by Wako Pure Chemical Industries) was charged, and nitrogen gas was passed through while stirring at 200 rpm. After 30 minutes, the temperature was raised to 50° C. and held for 3 hours. After that, it was kept at 70° C. for 2 hours. After cooling, a transparent polymer aqueous solution was obtained. The viscosity of the resulting 1% by mass aqueous solution of the polymer was 22.5 mPa·s. The results are shown in Table 1.

(Comparative example 2)
In a 500 mL four-neck flask, 0.50 g of dodecyl acrylate, 7.5 g of dimethylaminoethyl methacrylate, 5.0 g of 35% by weight hydrochloric acid, 84.0 g of 50% by weight acrylamide, 153.0 g of demineralized water, 0 sodium methallyl sulfonate 0.1 g of VA-044 (manufactured by Wako Pure Chemical Industries, Ltd.) and 0.1 g of VA-044 (manufactured by Wako Pure Chemical Industries, Ltd.) were charged and nitrogen gas was passed through while stirring at 200 rpm. After 30 minutes, the temperature was raised to 50° C. and held for 3 hours. After that, it was kept at 70° C. for 2 hours. After cooling, a transparent polymer aqueous solution was obtained. The viscosity of the resulting 1% by mass aqueous solution of the polymer was 22.5 mPa·s. The results are shown in Table 1.

(Comparative Example 3)
1.0 g of dodecyl acrylate, 7.5 g of dimethylaminoethyl methacrylate, 5.0 g of 35% by weight hydrochloric acid, 83.0 g of 50% by weight acrylamide, 153.5 g of demineralized water, 0 sodium methallyl sulfonate, 153.5 g of demineralized water, 0.1 g of VA-044 (manufactured by Wako Pure Chemical Industries, Ltd.) and 0.1 g of VA-044 (manufactured by Wako Pure Chemical Industries, Ltd.) were charged and nitrogen gas was passed through while stirring at 200 rpm. After 30 minutes, the temperature was raised to 50° C. and held for 3 hours. After that, it was kept at 70° C. for 2 hours. After cooling, a transparent polymer aqueous solution was obtained. The viscosity of the resulting 1% by mass aqueous solution of the polymer was 18.5 mPa·s. The results are shown in Table 1.

(Comparative Example 4)
In a 500 mL four-necked flask, 1.0 g of dodecyl acrylate, 1.0 g of styrene, 7.5 g of dimethylaminoethyl methacrylate, 5.0 g of 35% by weight hydrochloric acid, 81.0 g of 50% by weight acrylamide, 154.5 g of demineralized water, meth 0.30 g of sodium lylsulfonate and 0.1 g of VA-044 (manufactured by Wako Pure Chemical Industries) were charged, and nitrogen gas was passed through while stirring at 200 rpm. After 30 minutes, the temperature was raised to 50° C. and held for 3 hours. After that, it was kept at 70° C. for 2 hours. After that, it was cooled to obtain an aqueous polymer solution. The obtained polymer was mixed with 0.10 g of polyoxyethylene sorbitan trioleate (TW-85 manufactured by Wako Pure Chemical Industries, Ltd.). The viscosity of the resulting 1% by mass aqueous solution of the polymer was 17.5 mPa·s. The results are shown in Table 1.

疎水性単量体；ＤＤＡ：ドデシルアクリレート、Ｓｔ：スチレン、２ＥＨＡ：２－エチルへキシルアクリレート、ＯＤＭＡ：オクダデシルメタクリレート、ＢＭＡ：ブチルメタクリレート
カチオン性単量体；ＤＭＭ：ジメチルアミノエチルメタクリレート
ＡＡＭ；アクリルアミド
その他の単量体；ＡＡＣ：アクリル酸、ＭＢＡＡ：メチレンビスアクリルアミド
界面活性剤；ＳＤＳ：ドデシル硫酸ナトリウム、ＷＳ－１００：ナフタレンスルホネート・ホルマリン縮合物、ＣＬ－１００：ポリオキシアルキレンアルキルエーテル、ＴＷ－８５：ポリオキシエチレンソルビタントリオレエート (Table 1)

Hydrophobic monomers; DDA: dodecyl acrylate, St: styrene, 2EHA: 2-ethylhexyl acrylate, ODMA: octadecyl methacrylate, BMA: butyl methacrylate cationic monomers; DMM: dimethylaminoethyl methacrylate AAM; acrylamide and others AAC: acrylic acid, MBAA: methylenebisacrylamide surfactant; SDS: sodium dodecyl sulfate, WS-100: naphthalene sulfonate formalin condensate, CL-100: polyoxyalkylene alkyl ether, TW-85: Polyoxyethylene sorbitan trioleate

(Test example 1)
A paper quality measurement test of the paper strength agent in the present invention was carried out. First, LBKP was beaten with a Niagara beater and adjusted to a Canadian standard freeness of 345 mL. The polymer sample or A polymer sample of a comparative example and a commercially available paper strength agent (amphoteric acrylamide-based water-soluble polymer, concentration 20% by mass) were added as a comparative sample, stirred at 800 rpm for 1 minute, and then paper-made with a tapping sheet machine (80 mesh wire ), then pressed at a pressure of 410 kPa for 5 minutes, and further dried at 105° C. using a rotary dryer. The paper was conditioned at a temperature of 23° C. and a humidity of 50% for 24 hours to obtain a paper having a basis weight of 80 g/cm ² . The resulting paper was measured for internal bond strength (internal bond tester manufactured by Kumagai Riki Kogyo Co., Ltd.) and burst strength according to JIS P8112, and the results shown in Table 2 were obtained. The practical test examples showed an improvement in paper strength compared to the papers of the comparative test examples.

(Table 2)

(Test example 2)
For 500 mL of slurry with a pulp concentration of 1% by mass prepared in the same manner as in Test Example 1 (beating degree: 360 mL), the polymer of the example in Table 1 was added so that it was 0.5% by mass or 1% by mass with respect to the pulp solid content. A sample or a polymer sample of a comparative example and a comparative sample are added, stirred at 800 rpm for 1 minute, paper is made with a tapping sheet machine (80 mesh wire), followed by pressing at a pressure of 410 kPa for 5 minutes, and further with a rotary dryer. and dried at 105°C. The paper was conditioned at a temperature of 23° C. and a humidity of 50% for 24 hours to obtain a paper having a basis weight of 80 g/cm ² . The internal bond strength (internal bond tester manufactured by Kumagai Riki Kogyo Co., Ltd.) and the burst strength of the obtained paper were measured according to JIS P8112, and the results shown in Table 3 were obtained. The practical test examples showed an improvement in paper strength compared to the papers of the comparative test examples.

(Table 3)

(Test example 3)
For 500 mL of slurry with a pulp concentration of 1% by mass prepared in the same manner as in Test Example 1 (beating degree: 360 mL), the polymer of the example in Table 1 was added so that it was 0.5% by mass or 1% by mass with respect to the pulp solid content. A sample or a polymer sample of a comparative example and a comparative sample are added, stirred at 800 rpm for 1 minute, paper is made with a tapping sheet machine (80 mesh wire), followed by pressing at a pressure of 410 kPa for 5 minutes, and further with a rotary dryer. and dried at 105°C. The paper was conditioned at a temperature of 23° C. and a humidity of 50% for 24 hours to obtain a paper having a basis weight of 80 g/cm ² . The internal bond strength of the obtained paper (internal bond tester manufactured by Kumagai Riki Kogyo Co., Ltd.) and the burst strength were measured according to JIS P8112, and the results shown in Table 4 were obtained. The practical test examples showed an improvement in paper strength compared to the papers of the comparative test examples.

(Table 4)

(Test example 4)
For 500 mL of slurry with a pulp concentration of 1% by mass prepared in the same manner as in Test Example 1 (beating degree: 360 mL), the polymer sample of the example in Table 1 or the high polymer sample of the comparative example was added so that the pulp solid content was 1% by mass. A molecular sample and a comparative sample were added, and after stirring at 800 rpm for 1 minute, the mixture was made into paper (80 mesh wire) using a tapping sheet machine, followed by pressing at a pressure of 410 kPa for 5 minutes, and further using a rotary dryer at 105°C. Dried. The paper was conditioned at a temperature of 23° C. and a humidity of 50% for 24 hours to obtain a paper having a basis weight of 80 g/cm ² . The resulting paper was measured for internal bond strength (internal bond tester manufactured by Kumagai Riki Kogyo Co., Ltd.) and burst strength according to JIS P8112, and the results shown in Table 5 were obtained. The practical test examples showed an improvement in paper strength compared to the papers of the comparative test examples.

(Table 5)

(Test Example 5)
For 500 mL of slurry with a pulp concentration of 1% by mass prepared in the same manner as in Test Example 1 (beating degree 360 mL), the polymer sample of the example in Table 1 or the high polymer sample of the comparative example was added so that the pulp solid content was 1% by mass. A molecular sample and a comparative sample were added, and after stirring at 800 rpm for 1 minute, the mixture was made into paper (80 mesh wire) using a tapping sheet machine, followed by pressing at a pressure of 410 kPa for 5 minutes, and further using a rotary dryer at 105°C. Dried. The paper was conditioned at a temperature of 23° C. and a humidity of 50% for 24 hours to obtain a paper having a basis weight of 80 g/cm ² . The internal bond strength (internal bond tester manufactured by Kumagai Riki Kogyo Co., Ltd.) and the burst strength of the obtained paper were measured according to JIS P8112, and the results shown in Table 6 were obtained. The practical test examples showed an improvement in paper strength compared to the papers of the comparative test examples.

(Table 6)

Claims (4)

As hydrophobic monomers, one or more selected from butyl (meth)acrylate, octyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, dodecyl (meth)acrylate, octadecyl (meth)acrylate, styrene, ( meth)acrylamide, as cationic monomers, inorganic or organic acid salts of dimethylaminoethyl (meth)acrylate, diethylaminoethyl (meth)acrylate, dimethylaminopropyl (meth)acrylamide, diethylaminopropyl (meth)acrylamide, or One selected from monomers having a quaternary ammonium salt obtained by reacting these tertiary amino group-containing monomers with a quaternizing agent such as methyl chloride, benzyl chloride, dimethyl sulfate and epichlorohydrin A monomer mixture containing the above essential components and not containing a reactive surfactant, water, a surfactant, and a radical polymerization initiator are added to a predetermined reaction vessel, and stirred and heated under an inert gas atmosphere . A method for producing a paper strength agent, comprising a polymer obtained by polymerizing in water. As hydrophobic monomers, one or more selected from butyl (meth)acrylate, octyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, dodecyl (meth)acrylate, octadecyl (meth)acrylate, styrene, ( meth)acrylamide, as cationic monomers, inorganic or organic acid salts of dimethylaminoethyl (meth)acrylate, diethylaminoethyl (meth)acrylate, dimethylaminopropyl (meth)acrylamide, diethylaminopropyl (meth)acrylamide, or One selected from monomers having a quaternary ammonium salt obtained by reacting these tertiary amino group-containing monomers with a quaternizing agent such as methyl chloride, benzyl chloride, dimethyl sulfate and epichlorohydrin A monomer mixture containing the above essential components and not containing a reactive surfactant, water, a surfactant, and a radical polymerization initiator are added to a predetermined reaction vessel, and stirred and heated under an inert gas atmosphere . A polymer obtained by polymerizing in water according to A method for producing a paper strength agent, comprising: As hydrophobic monomers, one or more selected from butyl (meth)acrylate, octyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, dodecyl (meth)acrylate, octadecyl (meth)acrylate, styrene, ( meth)acrylamide, as cationic monomers, inorganic or organic acid salts of dimethylaminoethyl (meth)acrylate, diethylaminoethyl (meth)acrylate, dimethylaminopropyl (meth)acrylamide, diethylaminopropyl (meth)acrylamide, or One selected from monomers having a quaternary ammonium salt obtained by reacting these tertiary amino group-containing monomers with a quaternizing agent such as methyl chloride, benzyl chloride, dimethyl sulfate and epichlorohydrin A monomer mixture containing the above essential components and not containing a reactive surfactant, water, a surfactant, and a radical polymerization initiator are added to a predetermined reaction vessel, and stirred and heated under an inert gas atmosphere . A polymer obtained by polymerizing in water according to A method for producing a paper strength agent, comprising a polymer obtained by polymerizing in water in the presence of %. The paper strength agent according to any one of claims 1 to 3, wherein the viscosity of the 1 mass% aqueous solution of the polymer is 5 to 50 mPa s at a rotation speed of 60 rpm and a temperature of 25 ° C. measured by a Brookfield viscometer. manufacturing method.