JP7047310B2 - Paper strength enhancer and paper - Google Patents

Description

The present invention relates to a paper strength enhancer and paper.

Conventionally, as the paper strength enhancer, for example, (meth) acrylamide-based polymers and starch have been mainly used. Although the (meth) acrylamide-based polymer is more expensive than starch, it has high fixability to pulp and exhibits excellent paper strength effect even when added in a small amount. On the other hand, although starch is inexpensive, it has a lower fixing property to pulp than an acrylamide-based polymer, so that it is necessary to add a large amount to the solid content of the pulp slurry in order to exert a high paper strength effect.

Therefore, various studies have been conducted to provide a relatively inexpensive and high-performance paper strength enhancer by reacting the (meth) acrylamide-based polymer and starch in order to utilize the advantages of each.

For example, a papermaking additive (Patent Documents 1 and 2) obtained by polymerizing a monomer mixture containing acrylamide as a main component in an aqueous dispersion containing an aqueous dispersible polysaccharide such as starch, or a specific chain transfer in advance. A polysaccharide-acrylamide-based polymer having a graft structure obtained by producing an acrylamide-based polymer having a vinyl monomer having a sex substituent as a constituent component and graft-polymerizing the acrylamide-based polymer with the water-dispersible polysaccharide is obtained. It is known. (Patent Document 3). In addition, the applicant is an additive for papermaking obtained by reacting starch modified with a crosslinkable vinyl monomer having a chain transfer substituent and an acrylamide polymer (B) in the presence of a peroxide. (Patent Document 4) is disclosed.

However, although these can be improved to some extent in terms of price and performance, they cannot meet the demands of the paper industry to achieve further price reduction and performance improvement, and are relatively inexpensive and high-performance papermaking. Chemicals are in demand.

Japanese Unexamined Patent Publication No. 8-60591 Japanese Patent No. 2928785 Japanese Patent No. 3371931 Japanese Unexamined Patent Publication No. 2016-066788

It is an object of the present invention to provide a paper strength enhancer and paper which are cheaper and have an excellent paper strength effect as compared with the conventional starch- (meth) acrylamide polymer.

As a result of diligent studies focusing on the above-mentioned problems, the present inventors have found that starch modified with a component having a (meth) acrylate group is effective, and the modified starch is converted into a monomer component containing (meth) acrylamide, or the above-mentioned We have found that a paper strength enhancer obtained by reacting with one of the polymers of the monomer component solves the above-mentioned problems, and has completed the present invention. That is, the present invention relates to the following paper strength enhancer and paper.

1. 1. Starch (A) having an (meth) acrylate group in the molecule,
(Meta) A paper strength enhancer containing a reaction product with either a monomer component (B1) containing acrylamide (b1) or a polymer (B2) thereof.

2. 2. The paper strength enhancer according to item 1 above, wherein the component (A) is a reaction product between the component (a1) having a (meth) acrylate group and the raw material starch.

3. 3. (A1) The paper strength enhancer according to item 1 or 2 above, wherein the component is one selected from the group consisting of unsaturated monocarboxylic acid anhydride, unsaturated dicarboxylic acid anhydride, unsaturated glycidyl and unsaturated isocyanate.

4. The paper strength enhancer according to any one of the above items 1 to 3, wherein the raw material starch of the component (A) is an enzyme-reduced starch.

5. The paper strength enhancer according to any one of the above items 1 to 4, wherein the component (B1) contains (meth) acrylamide (b1) and a cationic vinyl monomer (b2) and / or an anionic vinyl monomer (b3).

6. Further, the paper strength enhancer according to the above item 5, which contains a crosslinkable vinyl monomer (b4) and a chain transfer agent (b5).

7. The paper strength enhancer according to any one of the above items 1 to 6, which has a concentration of 20% by weight and a viscosity at a temperature of 25 ° C. of 100 to 30,000 mPa · s.

8. Paper containing any of the paper strength enhancers 1 to 7 in the preceding paragraph.

According to the paper strength enhancer of the present invention, starch having a (meth) acrylate group in the molecule efficiently reacts with a monomer component containing acrylamide or a polymer thereof, and the obtained paper strength enhancer is an excellent paper. Has a force effect.

The paper strength enhancer of the present invention comprises a starch (A) having a (meth) acrylate group in the molecule (hereinafter referred to as (A) component) and a monomer component (B1) (hereinafter referred to as (B1)) containing (meth) acrylamide (b1). , (B1) component) or its polymer (B2) (hereinafter referred to as (B2) component) contains a reaction product.

Examples of the component (A) include a reaction product of a component (a1) having a (meth) acrylate group (hereinafter referred to as a component (a1)) and a raw material starch.

The component (a1) is used in order to exert a good paper strength effect because the obtained component (A) can be efficiently introduced into the acrylamide-based polymer. The component (a1) is not particularly limited as long as it has a functional group (for example, a carboxyl group, a glycidyl group, an isocyanate group, etc.) that reacts with the hydroxy group of the starch, and for example, acrylic acid, methacrylic acid, and croton. Unsaturated monocarboxylic acids such as acids and isocrotonic acids; unsaturated dicarboxylic acids such as itaconic acid, maleic acid, fumaric acid, muconic acid, citraconic acid and mesaconic acid; anhydrous acrylic acid, anhydrous methacrylic acid, anhydrous crotonic acid, anhydrous isocroton Unsaturated monocarboxylic acid anhydrides such as acids; unsaturated dicarboxylic acid anhydrides such as itaconic acid anhydride, maleic anhydride, fumaric acid anhydride, muconic anhydride, citraconic anhydride, etc .; glycidyl acrylate, glycidyl metaacrylate, allyl glycidyl ether, etc. Anhydrous glycidyl; unsaturated isocyanates such as isocyanate ethyl acrylate, isocyanate ethyl methacrylate, and 1,1- (bisacryloyloxymethyl) ethyl isocyanate can be mentioned. These may be used alone or in combination of two or more. Above all, by efficiently introducing the (meth) acrylate group derived from the component (a1) into the raw material starch, the reactivity with the component (B1) or the component (B2) is excellent, and the resulting paper strength is obtained. One selected from the group consisting of unsaturated monocarboxylic acid anhydride, unsaturated dicarboxylic acid anhydride, unsaturated glycidyl and unsaturated isocyanate is preferable because the enhancer exerts an excellent paper strength effect. , Maleic anhydride, glycidyl acrylate, glycidyl methacrylate and isocyanate ethyl methacrylate are more preferred.

The raw material starch is not particularly limited, and various known starches can be used, for example, unmodified starch obtained from corn, horse bell 薯, tapioca, wheat, rice, sago palm, waxy corn, and high amylose; cationized starch, oxidized starch. , Phosphoric acid-modified starch, carboxymethylated starch, amine-modified starch, hydroxyethylated starch, carbamylethylated starch, cyanoethylated starch, dialdehyde-modified starch, acetic acid-modified starch, modified starch such as TEMPO-oxidized starch, and the like. .. These may be used alone or in combination of two or more. Further, a commercially available product may be used.

Further, as the raw material starch, unmodified starch, modified starch or the like that has been reduced (hereinafter referred to as reduced starch) can be used. The reduced starch is not particularly limited, and examples thereof include peroxide-modified starch obtained by treating the raw material starch with an inorganic peroxide; and enzyme-modified starch obtained by treating the raw material starch with an enzyme. .. The reduced starch can be produced by heating and stirring an aqueous solution consisting of the starch and the reducing agent at 60 to 100 ° C. for 30 to 60 minutes.

The inorganic peroxide used for producing the peroxide-decreased starch is not particularly limited, and is, for example, hypochlorite, peroxodisulfate (ammonium persulfate, potassium persulfate, sodium persulfate, etc.), and peroxide. Examples include hydrogen peroxide. The peroxide may be used alone or in combination of two or more. Further, hydrogen peroxide can be used in combination with at least one water-soluble heavy metal salt of iron sulfate and copper sulfate. Among these, at least one of ammonium persulfate, potassium persulfate and sodium persulfate can be preferably used.

As the enzyme used for producing the enzyme-reduced starch, for example, α-amylase produced by various bacteria, animals and plants is preferably used.

In the paper strength enhancer of the present invention, the enzyme-modified starch is preferable because the reaction solution does not excessively thicken during the reaction with the component (a1) and the obtained component (A) tends to have a low viscosity.

The amount of the component (a1) and the raw material starch used is not particularly limited, but the raw material starch / (a1) component = about 50/50 to 99.9 / 0.1, preferably 92/8 to 99.5 / 0. It is about 5.5, more preferably about 96/4 to 99/1. Within the above numerical range, thickening is less likely to occur during the reaction with the component (B1) or the component (B2).

The method for producing the component (A) is not particularly limited, but for example, after the raw material starch is dispersed in a solvent, the component (a1) is mixed and the temperature is about 5 to 90 ° C. (preferably about 5 to 30 ° C.). ) For about 5 to 300 minutes (preferably about 15 to 120 minutes). The component having a (meth) acrylate group may be added by dropping. Since the component (A) obtained by this production method has a (meth) acrylate group in the molecule, it has an excellent reaction with the component (B1) or the component (B2), and the final paper strength enhancer is also a good paper. It will exert a powerful effect.

The solvent is not particularly limited, and water (ion-exchanged water, pure water, tap water, etc.), an organic solvent, or the like can be appropriately used. The organic solvent is not particularly limited as long as it can easily dissolve or disperse the raw starch at room temperature or heating, and is, for example, dimethyl sulfoxide, N-2-methylpyrrolidone, N, N-dimethylformamide, N, N. -Includes dimethylacetamide, acetonitrile and the like. These may be used alone or in combination of two or more. Further, in the present invention, the component (a1) may be sprayed onto the powdery starch without a solvent, but it is preferable to use the solvent, and water is particularly preferable from the viewpoint of reducing the environmental load. The amount of the solvent used is not particularly limited, and the concentration is preferably adjusted to about 0.1 to 50% by weight in consideration of the reactivity between the component (a1) and the raw material starch.

The physical properties of the obtained component (A) are not particularly limited, but for example, the viscosity at a concentration of 15% by weight and a temperature of 25 ° C. is such that the final paper strength enhancer exerts an excellent paper strength effect. It is usually about 50 to 30,000 mPa · s, preferably about 100 to 25,000 mPa · s.

The component (B1) is a monomer component containing (meth) acrylamide (b1), and examples thereof include (meth) acrylamide (b1) (hereinafter referred to as component (b1)) and a cationic vinyl monomer (b2) ( Hereinafter, it contains (b2) component) and anionic vinyl monomer (b3) (hereinafter, referred to as (b3) component).

The component (b1) means acrylamide and methacrylamide.

The component (b2) is not particularly limited, and various known components can be used. However, from the viewpoint of exhibiting an excellent paper strength effect, a tertiary amino group-containing vinyl monomer and / or the vinyl monomer 4 thereof. It preferably contains a graded salt. Specific examples of the tertiary amino group-containing vinyl monomer are not particularly limited, and for example, N, N-dimethylaminoethyl (meth) acrylate, N, N-diethylaminoethyl (meth) acrylate, N, N-dimethylaminopropyl. Examples thereof include (meth) acrylamide, N, N-diethylaminopropyl (meth) acrylamide and the like. Examples of the quaternized salt of the vinyl monomer include those obtained by reacting a tertiary amino group-containing vinyl monomer with a quaternizing agent. Further, the quaternized salt may be an inorganic acid salt such as a hydrochloride salt or a sulfate; an organic acid salt such as an acetate salt. The quaternizing agent is not particularly limited, and examples thereof include methyl chloride, benzyl chloride, dimethyl sulfate, epichlorohydrin and the like. These (b2) components may be used alone or in combination of two or more. Of these, benzyl chloride quaternized salts of N, N-dimethylaminoethyl (meth) acrylate and N, N-dimethylaminoethyl (meth) acrylate are preferable.

The component (b3) is not particularly limited, and various known substances can be used, but it is preferable to include a vinyl monomer having a carboxyl group from the viewpoint of exhibiting an excellent paper strength effect. Examples of the vinyl monomer include α, β-unsaturated monocarboxylic acids such as (meth) acrylic acid and crotonic acid; α, β-unsaturated acids such as maleic acid, fumaric acid, itaconic acid, muconic acid and citraconic acid. Dicarboxylic acid; organic sulfonic acid such as vinyl sulfonic acid and styrene sulfonic acid, sodium salt, potassium salt and the like of the acid can be mentioned. These may be used alone or in combination of two or more. Of these, acrylic acid and / or itaconic acid are preferred.

The content ratios of the component (b1), the component (b2) and the component (b3) are not particularly limited, but the ionic (cationic, anionic, amphoteric) and excellent paper strength effects of the obtained paper strength enhancer can be obtained. From the point of view of exertion, all the monomer components in the component (B1) are set to 100 mol%, and each is set as follows.

<In the case of cationic>
-Component (b1): Usually about 70 to 99.5 mol%, preferably about 79.5 to 99 mol%, more preferably about 83.5 to 98.5 mol%-(b2) component: Usually 0 .5 to 30 mol%, preferably about 1 to 20 mol%, more preferably about 1.5 to 15 mol%

<In the case of anionic>
-Component (b1): Usually about 75 to 99.5 mol%, preferably about 79.5 to 99 mol%, more preferably about 83.5 to 98.5 mol%-(b3) component: Usually 0 .5 to 25 mol%, preferably about 0.8 to 20 mol%, more preferably about 1 to 15 mol%

<In the case of both sexes>
-(B1) component: usually about 45 to 99 mol%, preferably about 60 to 98 mol%, more preferably about 75 to 97 mol%- (b2) component: usually about 0.5 to 30 mol%, It is preferably about 1 to 20 mol%, more preferably about 1.5 to 15 mol%, and (b3) component: usually about 0.5 to 25 mol%, preferably about 0.8 to 20 mol%, more preferably. Is about 1 to 15 mol%

Further, the component (B1) may be appropriately mixed with a crosslinkable vinyl monomer (b4) and a chain transfer agent (b5) for the purpose of adjusting the weight average molecular weight.

The component (b4) is not particularly limited, and is, for example, a divinyl ester such as divinyl adipate or divinyl sebacate; diethylene glycol mono (meth) acrylate, triethylene glycol mono (meth) acrylate, or tetraethylene glycol mono (meth) acrylate. Polyethylene glycol mono (meth) acrylate such as ethylene glycol di (meth) acrylate, polyethylene glycol di (meth) acrylate such as diethylene glycol di (meth) acrylate; polypropylene glycol mono (meth) acrylate, methoxypolyethylene glycol mono (meth) acrylate. , Polyalkylene glycol mono (meth) acrylates such as polytrimethylene glycol mono (meth) acrylates, polytetramethylene glycol mono (meth) acrylates, polyethylene glycol propylene glycol mono (meth) acrylates; N- (1,1-dimethyl-). N-substituted (meth) acrylamides such as 3-oxobutyl) acrylamide, N-isopropylacrylamide, N-methylolacrylamide, N-allyl (meth) acrylamide, 2-acrylamide-2-methylpropanesulfonic acid and salts thereof; N, N N, N-substituted (meth) acrylamides such as -dimethylacrylamide, N, N-diethylacrylamide, N, N-diallyl (meth) acrylamide; N, N'-methylenebis (meth) acrylamide, N, N'-ethylenebis ( N, N'-substituted (meth) acrylamide such as meta) acrylamide; divinylbenzene, 1,3,5-triacrylloylhexahydro-1,3,5-triazine, triallyl isocyanurate, triallyl trimellitate, tri. Aromatic polyvinyls such as allylamine, tetramethylolmethanetetraacrylate and tetraallylpyrromelylate; allyl (meth) acrylates, triacrylic formal and the like can be mentioned. These may be used alone or in combination of two or more. Of these, N, N-substituted (meth) acrylamide is preferable, and N, N-dimethylacrylamide is more preferable, because the weight average molecular weight is appropriately adjusted and the paper strength effect is excellent.

The content ratio of the component (b4) is not particularly limited, but from the viewpoint of paper strength effect, the total content ratio of the component (B1) is 100 mol%, and is usually about 0 to 10 mol%, preferably 0.02 to 0.02. It is about 5 mol%, more preferably about 0.1 to 2 mol%.

As the component (b5), the polymer chain before the crosslinking reaction becomes shorter, and a copolymer having a lower viscosity and a higher molecular weight can be obtained. The component (b5) is not particularly limited, and is, for example, mercaptans such as 2-mercaptoethanol and n-dodecyl mercaptan, α-methylstyrene dimer, sodium methallyl sulfonate, potassium methallyl sulfonate and methallyl sulfonic acid. Metalyl sulfonates such as ammonium, ethanol, alcohols without allyl groups such as isopropyl alcohol and pentanol, carbon tetrachloride, ethylbenzene, isopropylbenzene, cumene, 2,4-diphenyl-4-methyl-1- Examples include penten. These may be used alone or in combination of two or more. Among them, methallyl sulfonate is preferable, and sodium metharyl sulfonate is more preferable, from the viewpoint of adjusting the weight average molecular weight and viscosity of the paper strength enhancer.

The content ratio of the component (b5) is usually about 0 to 20 mol%, preferably about 0.1 to 10 mol%, with the total content ratio of (B1) being 100 mol%, from the viewpoint of paper strength effect. It is preferably about 0.2 to 5 mol%.

Further, the component (B1) may contain a component (b6) (hereinafter referred to as a component (b6)) other than the components (b1) to (b5). The component (b6) is not particularly limited, and is, for example, an aromatic vinyl monomer such as styrene, α-methylstyrene, vinyltoluene, etc .; methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate. , (Meta) butyl acrylate, (meth) -2-ethylhexyl acrylate, alkyl (meth) acrylates such as cyclohexyl (meth) acrylate; vinyl carboxylic acid esters such as vinyl acetate, vinyl propionate and the like. These may be used alone or in combination of two or more.

The content ratio of the component (b6) is not particularly limited, but the total content ratio of the component (B1) is 100 mol%, and is usually 5 mol% or less, preferably 1 mol% or less.

The component (B2) is a polymer of the component (B1), and depending on its ionicity, a nonionic acrylamide polymer, an anionic acrylamide polymer, a cationic acrylamide polymer, and an amphoteric acrylamide polymer. Classified as coalesced. Further, examples of the monomer component forming the (B2) component include the above-mentioned (b1) to (b6) components, and the content ratio thereof is also set according to the ionicity of the (B2) component as described above. be.

The method for producing the component (B2) is not particularly limited, and for example, a conventionally known monomer dropping polymerization method, a simultaneous polymerization method in which a monomer solution is collectively charged, or a method in which these are combined is used in the presence of a polymerization initiator. Can be mentioned. The production conditions are not particularly limited, but for example, the temperature is usually about 30 to 90 ° C., preferably about 70 to 90 ° C., and the time is usually about 15 minutes to 10 hours, preferably about 30 minutes to 5 hours. be. The solvent used in the monomer mixed solution is not particularly limited as long as it dissolves or disperses each monomer component and does not adversely affect the polymerization reaction, but it is usually preferable to use water.

The polymerization initiator is not particularly limited, and for example, persulfates such as ammonium persulfate, potassium persulfate, and sodium persulfate, and azo compounds such as 2,2'-azobis (2-amidinopropane) hydrochloride, etc. Examples include hydrogen peroxide. These may be used alone or in combination of two or more. Among them, ammonium persulfate, potassium persulfate and / or 2,2'-azobis (2-amidinopropane) hydrochloride are preferable from the viewpoint of sufficiently advancing the polymerization reaction of the polymerization component (A). Further, the method of adding the polymerization initiator is not particularly limited, and batch addition, partial addition, continuous dropping, or the like can be appropriately selected. Further, the amount of the polymerization initiator used is not particularly limited, and is usually about 0.001 to 5 parts by weight, preferably about 0.01 to 1 part by weight, based on 100 parts by weight of all the monomer components.

Further, although optional, in terms of facilitating the generation of radicals of peroxide, for example, sulfites such as sodium sulfite, hydrogen sulfites such as sodium hydrogen sulfite, triethanolamine, ferrous sulfate, iron sulfate and the like can be used. Can be used.

The component (B2) obtained by the above-mentioned production method may contain unreacted components (b1) to (b6).

The physical properties of the component (B2) are not particularly limited, but for example, the weight average molecular weight by the gel permeation chromatography (GPC) method is usually about 50,000 to 10,000,000 from the viewpoint of paper strength effect. It is preferably about 100,000 to 8,000,000. The form of the component (B2) is preferably an aqueous solution.

In addition, the viscosity of the component (B2) is usually about 50 to 50,000 mPa · s, preferably about 100 to 30,000 mPa · s in an aqueous solution (temperature 25 ° C.) having a concentration of 20% by weight. ..

The method for producing the paper strength enhancer is not particularly limited, and examples thereof include a step of reacting the component (A) and the component (B1).

The ratio of the component (A) and the component (B1) [total weight of the components (b1) to (b6)] used in the production method is not particularly limited, but from the viewpoint of paper strength effect, the solid content weight of (A) is not particularly limited. ) / (B1) = about 5/95 to 95/5, more preferably about 10/90 to 90/10.

The production conditions are not particularly limited, but a polymerization initiator is added to the component (A) and the component (B1) (a mixed solution of the components (b1) to (b6)), and the temperature is about 50 to 90 ° C. It is desirable to do it in about 15 minutes to 6 hours. The type and amount of the polymerization initiator are as described above. In the production, the component (B1) may be added to the component (A) as it is, or the component (B1) may be added by dropping. In the present invention, the step of dropping the mixed solution of the component (A) and the component (B1) into the solvent is preferable from the viewpoint of obtaining a reaction product having a high molecular weight.

Examples of the method for producing another paper strength enhancer include a step of reacting the component (A) and the component (B2).

The ratio of the component (A) and (B2) used in the production method is not particularly limited, but from the viewpoint of paper strength effect, (A) / (B2) = 5/95 to 95/5 in terms of solid content weight. Is preferable, and about 10/90 to 90/10 is more preferable.

The production conditions are not particularly limited, but a peroxide and / or an azo compound is added to the mixed solution of the component (A) and the component (B2), and the temperature is about 50 to 90 ° C. (preferably 70 to 90 ° C.). About), it is desirable to carry out in about 5 minutes to 3 hours (preferably about 15 minutes to 2 hours). In the production, the component (A) may be added to the component (B2) all at once or in a divided manner, or may be further added by dropping.

The peroxide is not particularly limited, and examples thereof include ammonium persulfate, potassium persulfate, sodium persulfate, hydrogen peroxide, and the like, and azo compounds are also not particularly limited, and examples thereof include 2,2'-. Examples thereof include azobis (2-amidinopropane) hydrochloride. These may be used alone or in combination of two or more. Further, the amount used thereof is not particularly limited, and is usually about 0.001 to 5 parts by weight, preferably 0.01 to 1 part by weight, based on 100 parts by weight of the total of the component (A) and the component (B2). Degree. Further, for example, sulfites such as sodium sulfite, hydrogen sulfites such as sodium hydrogen sulfite, triethanolamine, ferrous sulfate, iron sulfate and the like may be used.

The concentration of the paper strength enhancer obtained by these production methods is not particularly limited, but is usually about 5 to 50% by weight, preferably about 10 to 50% by weight, from the viewpoint of transportation cost. The other physical properties are not particularly limited, but for example, from the viewpoint of paper strength effect, the viscosity in an aqueous solution (temperature 25 ° C.) having a concentration of 20% by weight is usually about 100 to 30,000 mPa · s, preferably 200. It is about 25,000 mPa · s.

Various additives may be added to the paper strength enhancer, if necessary, as long as the object and effect of the present invention are not deviated. The additive is not particularly limited, and examples thereof include a defoaming agent, a preservative, a chelating agent, a water-soluble aluminum compound, bow glass, urea, ammonium sulfate, sodium chloride and the like.

The paper of the present invention contains the paper strength enhancer. Examples of the method for producing the same include a method in which a paper strength enhancer is diluted with ion-exchanged water or the like in advance and then internally added to a raw material pulp slurry, or coated on the surface of a base paper, or a combination thereof.

In the case of internal addition, the paper strength enhancer of the present invention is added to the pulp slurry to make paper. The amount of the paper strength enhancer used is not particularly limited, but is about 0.01 to 4% by weight with respect to the solid content weight of the pulp slurry. The type of pulp slurry is also not particularly limited, and examples thereof include chemical pulps such as LBKP and NBKP, mechanical pulps such as GP and TMP, and used paper pulps. In addition, when adding it internally, in addition, sulfuric acid band, aluminum hydroxide, etc., pH adjuster, sulfuric acid, sodium hydroxide, etc., sizing agent, wet paper strength agent, filler, talc, clay, kaolin, titanium dioxide, etc. And calcium carbonate and the like may be added.

In the case of surface coating, the surface of the base paper is coated by various known means. The viscosity of the paper strength enhancer (coating liquid) before coating is usually 1 to 50 mPa · s at 50 ° C. at a concentration of 5% by weight. As the type of base paper, uncoated paper made from wood cellulose fiber can be used, and the coating means is not particularly limited. For example, bar coater, knife coater, air knife coater, calender, gate. Examples include roll coaters, blade coaters, 2-roll size presses and rod metering. Further, the coating amount (solid content) of the paper strength enhancer is not particularly limited, but is usually about 0.001 to 2 g / m ² , preferably about 0.005 to 1 g / m ² .

The paper of the present invention is provided in various products and can be used as, for example, coated base paper, newspaper paper, liner, core, paper tube, printing writing paper, foam paper, PPC paper, inkjet paper, heat-sensitive paper and the like.

Hereinafter, the present invention will be specifically described with reference to Examples and Comparative Examples. Both parts and% are based on weight. For convenience, monomers and the like are abbreviated as follows.

AM: Acrylamide AA: Acrylamide IA: Itaconic acid DM: N, N-dimethylaminoethyl (meth) acrylate DML: benzyl chloride quaternary product of DM DMAA: N, N-dimethylacrylamide SMAS: Sodium methallyl sulfonate APS: Ammonium persulfate GMA: Glysidyl methacrylate GA: Glysidyl acrylate MAA: Maleic anhydride IAA: Itaconic anhydride IEMA: isocyanate ethyl methacrylate PO: Propylene oxide

(viscosity)
The viscosity of the sample adjusted to 25 ° C. was measured using a Brookfield type viscometer (manufactured by Toki Sangyo Co., Ltd.).
(Weight average molecular weight)
The molecular weight was measured by the gel permeation chromatography (GPC) method under the following measurement conditions.
GPC body: Tosoh Corporation column: Tosoh Corporation guard column 1 PWXL and 2 GMPWXL (temperature 40 ° C)
Eluent: 0.5 mol / L acetic acid buffer (0.5 mol / L acetic acid (manufactured by Wako Pure Chemical Industries, Ltd.) + 0.5 mol / L sodium acetate (manufactured by Kishida Chemical Industries, Ltd.) aqueous solution, pH about 4.2 )
Flow velocity: 0.8 mL / min Detector:
Viscotec TDA MODEL 301 (concentration detector and 90 ° light scattering detector and viscosity detector (temperature 40 ° C)) RALLS measurement sample: When the sample concentration is adjusted to 0.5% and then contains a cationic component. Was measured by adding an aqueous sodium hydroxide solution until the pH reached 10 to 12, immersing in a hot water bath at 80 ° C. or higher for 1 hour, adjusting the pH to 6 to 8 with sulfuric acid, and diluting to 0.025% with an eluent. ..

Synthesis example 1
A reactor equipped with a stirrer, a thermometer, a reflux condenser, and a nitrogen gas introduction tube, corn starch with a solid content concentration of 88% (trade name "Cornstarch", manufactured by Oji Cornstarch Co., Ltd.), 100.0 parts, α- Add 0.03 part of amylase (trade name "Crystaze L1", manufactured by Amano Enzyme Co., Ltd.) and 480 parts of ion-exchanged water, raise the temperature to 75 ° C, stir for 40 minutes, and then raise the temperature to 90 ° C. The mixture was further stirred for 10 minutes. After cooling to 30 ° C., the pH was adjusted to 11 with 48% sodium hydroxide, and 1.0 part of GMA was added. Further, the mixture was stirred at 30 ° C. for 1 hour and diluted with ion-exchanged water so that the concentration became 15% to obtain the component (A-1). The viscosities of the obtained starch (A-1) are shown in Table 1 (the same applies hereinafter).

Synthesis Examples 2-7, 10-13
The compositions shown in Table 1 were synthesized in the same manner as in Synthesis Example 1 to obtain components (A-2) to (A-7) and (A-10) to (A-13).

Synthesis example 8
A reactor equipped with a stirrer, a thermometer, a reflux condenser, and a nitrogen gas introduction tube, corn starch with a solid content concentration of 88% (trade name "Cornstarch", manufactured by Oji Cornstarch Co., Ltd.), 100.0 parts, and ions. 480 parts of exchanged water was added, the temperature was raised to 90 ° C., and the mixture was further stirred for 10 minutes. After cooling to 30 ° C., the pH was adjusted to 11 with 48% sodium hydroxide, and 1.0 part of GMA was added. Further, the mixture was stirred at 30 ° C. for 1 hour and diluted with ion-exchanged water so that the concentration became 15% to obtain the component (A-8).

Synthesis example 9
A reactor equipped with a stirrer, a thermometer, a reflux condenser, and a nitrogen gas introduction tube, corn starch with a solid content concentration of 88% (trade name "Cornstarch", manufactured by Oji Cornstarch Co., Ltd.), 100.0 parts, APS1. 0 part and 480 parts of ion-exchanged water were added, the temperature was raised to 90 ° C., and the mixture was stirred for 40 minutes. After cooling to 30 ° C., the pH was adjusted to 11 with 48% sodium hydroxide, and 1.0 part of GMA was added. Further, the mixture was stirred at 30 ° C. for 1 hour and diluted with ion-exchanged water so that the concentration became 15% to obtain the component (A-9).

Comparative synthesis example 1
100 parts of corn starch (trade name "Corn Starch", manufactured by Oji Corn Starch Co., Ltd.) with a solid content concentration of 88% in a reaction device equipped with a stirrer, thermometer, reflux condenser, nitrogen gas introduction tube and three dropping funnels. , Α-amylase (trade name “Crystase L1”, manufactured by Amano Enzyme Co., Ltd.) 0.03 part, and ion-exchanged water 480 parts were added, the temperature was raised to 75 ° C., and after stirring for 40 minutes, the temperature was raised to 90 ° C. The mixture was warmed and stirred for another 10 minutes, and diluted with ion-exchanged water so that the concentration became 15% to obtain the component (C-1).

Comparative synthesis example 2
A component (C-2) was obtained by synthesizing in the same manner as in Synthesis Example 1 except that the component (a1) was changed to PO.

Comparative synthesis example 3
In Comparative Synthesis Example 1, the raw material starch was changed to cationized starch (trade name “CS-1”, manufactured by Arakawa Chemical Industry Co., Ltd.) and synthesized to obtain the component (C-3).

※表中の減成剤および成分（ａ１）の使用量は、原料澱粉の有姿に対する数値で示す。

* The amount of the reducing agent and the component (a1) used in the table is shown as a numerical value with respect to the appearance of the raw material starch.

Example 1-1 (A mixed solution of the component (A) and the component (B1) is dropped (hereinafter referred to as manufacturing method 1)).
268.4 parts of ion-exchanged water was placed in a reactor equipped with a stirrer, a thermometer, a reflux condenser, a nitrogen gas introduction tube and two dropping funnels, and after removing oxygen in the reaction system through nitrogen gas, 85. Heated to ° C. Separately, 284.8 parts of 50% AM aqueous solution, 10.4 parts of IA, 9.6 parts of 80% AA, 41.8 parts of DM, 62.8 parts of 60% DML, 8.8 parts of SMAS, 1.32 parts of DMAA are added to the dropping funnel (1). And 193.1 parts of ion-exchanged water and 416.7 parts of the previously prepared (A-1) component were charged. Further, 0.2 part of APS and 60 parts of ion-exchanged water were charged in the dropping funnel (2). Next, the dropping funnel (1) and (2) were added dropwise to the reactor over 3 hours. After completion of the dropping, 0.1 part of APS and 5.0 parts of ion-exchanged water were added and stirred for 1 hour. After cooling to 75 ° C., 0.1 part of APS and 5.0 parts of ion-exchanged water were added and stirred for 1 hour, the mixture was diluted with ion-exchanged water so that the concentration became 20% to obtain a reaction product.

Examples 1-2 to 1-30, Comparative Examples 1-1 to 1-3
The composition shown in Table 2 was adjusted, and the mixture was synthesized by the production method 1 to obtain reaction products.

Example 2-1 (Reaction of component (A) and component (B2) (hereinafter referred to as manufacturing method 2))
Put 300.0 parts of ion-exchanged water into a reaction device equipped with a stirrer, a thermometer, a reflux condenser, a nitrogen gas introduction tube and two dropping funnels, and after removing oxygen in the reaction system through nitrogen gas, 85 Heated to ° C. Separately, 284.8 parts of 50% AM aqueous solution, 10.4 parts of IA, 9.6 parts of 80% AA, 41.8 parts of DM, 62.8 parts of 60% DML, 8.8 parts of SMAS, 1.32 parts of DMAA are added to the dropping funnel (1). And 193.1 parts of ion-exchanged water were charged. Further, 0.2 part of APS and 60 parts of ion-exchanged water were charged in the dropping funnel (2). Next, the dropping funnel (1) and (2) were added dropwise to the reactor over 3 hours. After completion of the dropping, 0.1 part of APS and 5.0 parts of ion-exchanged water were added and stirred for 1 hour to obtain a polymer (B2-1). After adding 416.7 parts of the previously prepared (A-1) component, the mixture was cooled to 75 ° C., 0.1 part of APS and 5.0 parts of ion-exchanged water were added, and the mixture was stirred for 1 hour, and then the concentration was 20. The reaction product was obtained by diluting with ion-exchanged water so as to be%.

Examples 2-2 to 2-30, Comparative Examples 2-1 to 2-3
Hereinafter, the compositions shown in Table 2 were prepared and synthesized by the production method 2, respectively, to obtain reaction products.

Example 1-31 (Polymerizing component (B1) in component (A))
416.7 parts of the previously prepared (A-1) component was placed in a reaction device equipped with a stirrer, a thermometer, a reflux condenser, a nitrogen gas introduction tube and two dropping funnels, and the nitrogen gas was passed through the reaction system. After removing the oxygen, it was heated to 85 ° C. Separately, 284.8 parts of 50% AM aqueous solution, 10.4 parts of IA, 9.6 parts of 80% AA, 41.8 parts of DM, 62.8 parts of 60% DML, 8.8 parts of SMAS, 1.32 parts of DMAA are added to the dropping funnel (1). And 193.1 parts of ion-exchanged water were charged. Further, 0.2 part of APS and 60 parts of ion-exchanged water were charged in the dropping funnel (2). Next, the dropping funnel (1) and (2) were added dropwise to the reactor over 3 hours. After completion of the dropping, 0.1 part of APS and 5.0 parts of ion-exchanged water were added and stirred for 1 hour. After cooling to 75 ° C., 0.1 part of APS and 5.0 parts of ion-exchanged water were added and stirred for 1 hour, the mixture was diluted with ion-exchanged water so that the concentration became 20% to obtain a reaction product.

Examples 1-32 to 1-33, Comparative Example 1-4
The compositions shown in Table 3 were synthesized in the same manner as in Example 1-31, and reaction products were obtained.

(Performance evaluation method 1)
Beat the corrugated cardboard with a Niagara beater, add 1.5% aluminum sulfate to the pulp adjusted to 370 ml of Canadian Standard Freeness (CSF), and add 5% sodium hydroxide for pH adjustment. An aqueous solution was added to adjust the pH to 6.7. Next, each reaction product obtained in each Example and Comparative Example was added with 1.0% of pulp as a paper strength enhancer, stirred, and then subjected to a tappy sheet machine with a basis weight of 180 g / m ² . Paper was made so that it would be, and press dehydration was performed at 5 kg / cm ² for 2 minutes. Then, it was dried in a rotary dryer at 105 ° C. for 3 minutes, and the humidity was adjusted for 24 hours under the conditions of a temperature of 20 ° C. and a humidity of 65%.
(Ratio burst strength)
Using each test sheet obtained by the above method, the measurement was performed in accordance with JIS P 8131, and the specific burst strength (kPa · m ² / g) was shown. The results are shown in Tables 4 and 5. (Same below)
(Specific tensile strength)
Using each test sheet obtained by the above method, the measurement was performed in accordance with JIS P 8113, and the specific tensile strength (Nm / g) was shown.
(Specific compressive strength)
Using each test sheet obtained by the above method, the measurement was performed in accordance with JIS P 8126, and the specific compressive strength (Nm ² / g) was shown.

[Performance evaluation method 2]
(Preparation of coating liquid)
The reaction products shown in Table 6 were used as a paper strength enhancer and diluted with ion-exchanged water to a concentration of 5% to prepare coating solutions.

(Creation of coated paper)
Corrugated cardboard Waste paper Pulp was made from base paper (basis weight 150 g / m ² ), and the coating liquid heated to 50 ° C was applied to both sides of the base paper with a bar coater so that the solid adhesion amount was 0.50 g / m ² . It was coated and dried with a rotary drum dryer at 105 ° C. for 1 minute to obtain coated paper. The amount of solid adhesion of the coating liquid is a value calculated from the weight of the paperboard before and after coating.

(Viscosity of coating liquid)
Using a B-type viscometer (manufactured by Toki Sangyo Co., Ltd.), the viscosity of the coating liquid (concentration 5.0%) heated to 50 ° C. was measured. The results are shown in Table 6 (same below).

(Specific compressive strength)
Using each test sheet obtained by the above method, the measurement was performed in accordance with JIS P 8126, and the specific compressive strength (Nm ² / g) was shown.
(Internal strength)
Using each coated paper obtained by the above method, J. Tappi No. The internal strength (N / m) was measured according to 18-2.

Claims (6)

Starch (A) having an (meth) acrylate group in the molecule,
It contains a reaction product with either a monomer component (B1) containing (meth) acrylamide (b1) or a polymer (B2) thereof.
The component (A) is a reaction product of the component (a1) having a (meth) acrylate group and the raw material starch.
(A1) A paper strength enhancer whose component is one selected from the group consisting of unsaturated glycidyl and unsaturated isocyanate . The paper strength enhancer according to claim 1, wherein the raw material starch of the component (A) is an enzyme-reduced starch. The paper strength enhancer according to claim 1 or 2 , wherein the component (B1) comprises (meth) acrylamide (b1) and a cationic vinyl monomer (b2) and / or an anionic vinyl monomer (b3). The paper strength enhancer according to claim 3 , further comprising a crosslinkable vinyl monomer (b4) and / or a chain transfer agent (b5). The paper strength enhancer according to any one of claims 1 to 4 , wherein the concentration is 20% by weight and the viscosity at a temperature of 25 ° C. is 100 to 30,000 mPa · s. Paper containing the paper strength enhancer according to any one of claims 1 to 5 .