阅读说明：本技术 (甲基)丙烯酰胺系聚合物造纸用添加剂的制造方法及(甲基)丙烯酰胺系聚合物造纸用添加剂 (Method for producing (meth) acrylamide polymer additive for papermaking, and (meth) acrylamide polymer additive for papermaking ) 是由 堀井忠昭 佐藤博茂 栗原隆纪 藤原崇弘 稻冈和茂 于 2018-04-27 设计创作，主要内容包括：本发明提供一种(甲基)丙烯酰胺系聚合物造纸用添加剂的制造方法,该制造方法使含有(甲基)丙烯酰胺的第一聚合成分发生聚合得到第一聚合体,在该第一聚合体的存在下使含有叔氨基系单体的第二聚合成分发生聚合得到(甲基)丙烯酰胺系聚合物,其中,第一聚合成分和/或第二聚合成分含有(甲基)烯丙基磺酸盐,第一聚合成分中的叔氨基系单体相对于第一聚合成分中的(甲基)丙烯酰胺100摩尔为0.1摩尔以下,第二聚合成分中的(甲基)丙烯酰胺相对于第二聚合成分中的叔氨基系单体100摩尔为1.0摩尔以下。(The present invention provides a method for producing a (meth) acrylamide polymer additive for papermaking, which comprises polymerizing a first polymerization component containing (meth) acrylamide to obtain a first polymer, and polymerizing a second polymerization component containing a tertiary amino monomer in the presence of the first polymer to obtain a (meth) acrylamide polymer, wherein the first polymerization component and/or the second polymerization component contains (meth) allylsulfonate, the tertiary amino monomer in the first polymerization component is 0.1 mol or less based on 100 mol of (meth) acrylamide in the first polymerization component, and the (meth) acrylamide in the second polymerization component is 1.0 mol or less based on 100 mol of the tertiary amino monomer in the second polymerization component.)

1. A method for producing a (meth) acrylamide polymer-containing additive for papermaking, which is a method for producing a (meth) acrylamide polymer-containing additive for papermaking by polymerizing a polymerization component containing (meth) acrylamide, a tertiary amino monomer, and a (meth) allylsulfonic acid salt, the method comprising:

a first polymerization step of polymerizing a first polymerization component containing the (meth) acrylamide to obtain a first polymer,

a second polymerization step of polymerizing a second polymerization component containing the tertiary amino monomer in the presence of the first polymer obtained in the first polymerization step to obtain a (meth) acrylamide polymer;

said first polymeric component and/or said second polymeric component comprises said (meth) allylsulfonic acid salt,

the tertiary amino monomer in the first polymerization component is 0.1 mol or less based on 100 mol of (meth) acrylamide in the first polymerization component,

the amount of the (meth) acrylamide in the second polymerization component is 1.0 mol or less based on 100 mol of the tertiary amino monomer in the second polymerization component.

2. The method for producing a (meth) acrylamide-based polymer additive for papermaking according to claim 1, wherein the first polymerization component does not contain the tertiary amino monomer.

3. The method for producing a (meth) acrylamide-based polymer additive for papermaking according to claim 1, wherein the second polymerization component does not contain the (meth) acrylamide.

4. The method for producing a (meth) acrylamide polymer additive for papermaking according to claim 1, wherein the first polymerization component and/or the second polymerization component contains a quaternary ammonium salt monomer.

5. The method for producing a (meth) acrylamide-based polymer additive for papermaking according to claim 1, wherein the first polymerization component and/or the second polymerization component contains an anionic polymerizable monomer.

6. The process for producing a (meth) acrylamide polymer additive for papermaking according to claim 1,

the first polymeric component and/or the second polymeric component contain a nitrogen-containing crosslinking monomer,

the nitrogen-containing crosslinkable monomer in the first polymerizable component is 0.1 mol or less based on 100 mol of (meth) acrylamide in the first polymerizable component.

7. The method for producing a (meth) acrylamide-based polymer additive for papermaking according to claim 6, wherein the second polymerization component contains a nitrogen-containing crosslinkable monomer.

8. The method for producing a (meth) acrylamide-based polymer additive for papermaking according to claim 1, wherein the first polymerization component and/or the second polymerization component further contains another polymerizable monomer.

9. The method for producing the (meth) acrylamide polymer additive for papermaking according to claim 1, wherein the polymerization component is subjected to multistage polymerization in the first polymerization step and/or the second polymerization step.

10. An additive for (meth) acrylamide polymer paper making, which is obtained by polymerizing a polymerization component containing (meth) acrylamide, a tertiary amino monomer and (meth) allylsulfonate, and which is characterized by being obtained by the following steps:

first, a first polymer is obtained by polymerizing a first polymerization component containing (meth) acrylamide,

thereafter polymerizing a second polymerization monomer containing the tertiary amino monomer in the presence of the first polymer;

said first polymeric component and/or said second polymeric component comprises said (meth) allylsulfonic acid salt,

the tertiary amino monomer in the first polymerization component is 0.1 mol or less based on 100 mol of (meth) acrylamide in the first polymerization component,

the amount of the (meth) acrylamide in the second polymerization component is 1.0 mol or less based on 100 mol of the tertiary amino monomer in the second polymerization component.

Technical Field

The present invention relates to a method for producing an additive for producing a (meth) acrylamide polymer for papermaking and an additive for producing a (meth) acrylamide polymer for papermaking.

Background

Conventionally, in the field of papermaking, various papermaking chemicals such as yield increasing agents and drainage improving agents for improving the yield, drainage, workability, and working efficiency of pulp and/or fillers as raw materials, and paper strength improving agents for improving the strength of paper products have been known.

As such a paper-making chemical, a paper strength enhancer composed of an aqueous solution of a (meth) acrylamide polymer is known, and specifically, for example, a paper strength enhancer obtained by adding (meth) acrylamide, dimethylaminoethyl methacrylate, a quaternary ammonium salt product of dimethylaminoethyl methacrylate, itaconic acid, sodium methallyl sulfonate, methylene bisacrylamide (polyfunctional vinyl monomer), and ion-exchanged water, and adding a polymerization initiator (ammonium persulfate) to the mixture to cause a reaction, and obtaining an aqueous solution of amphoteric polyacrylamide, has been proposed (see patent document 1).

Disclosure of Invention

Problems to be solved by the invention

On the other hand, when the paper strength enhancer described in patent document 1 is used, the obtained paper product may contain (meth) acrylamide. (meth) acrylamide is not good for human body and is a subject of restriction by the U.S. Food and Drug Administration (FDA) and the like. Therefore, when the paper product is used for food packaging and the like, it is required to reduce the content of (meth) acrylamide in the paper product.

The present invention relates to a method for producing a (meth) acrylamide polymer additive for papermaking, which can reduce the content of (meth) acrylamide in paper while maintaining the performance of the additive for papermaking, and a (meth) acrylamide polymer additive for papermaking obtained by the method.

Means for solving the problems

The present invention [1] includes a method for producing a (meth) acrylamide polymer-containing additive for papermaking, which is a method for producing a (meth) acrylamide polymer-containing additive for papermaking by polymerizing polymerization components containing (meth) acrylamide, a tertiary amino (3 degree chef アミノ) -based monomer, and a (meth) allylsulfonate salt, the method comprising:

a first polymerization step of polymerizing a first polymerization component containing the (meth) acrylamide to obtain a first polymer,

a second polymerization step of polymerizing a second polymerization component containing the tertiary amino monomer in the presence of the first polymer obtained in the first polymerization step to obtain a (meth) acrylamide polymer;

the first polymeric ingredient and/or the second polymeric ingredient containing the (meth) allylsulfonate,

the tertiary amino monomer in the first polymerization component is 0.1 mol or less based on 100 mol of (meth) acrylamide in the first polymerization component,

the amount of the (meth) acrylamide in the second polymerization component is 1.0 mol or less based on 100 mol of the tertiary amino monomer in the second polymerization component.

The invention [2] is the method for producing the (meth) acrylamide polymer additive for papermaking according to [1], wherein the first polymerization component does not contain the tertiary amino monomer.

The invention [3] is the process for producing the (meth) acrylamide polymer additive for papermaking according to [1] or [2], wherein the second polymerization component does not contain the (meth) acrylamide.

The invention [4] is the method for producing a (meth) acrylamide-based polymer additive for papermaking according to any one of [1] to [3], wherein the first polymeric component and/or the second polymeric component contains a quaternary ammonium salt (アンモニウム) based monomer.

The invention [5] is the process for producing the (meth) acrylamide polymer additive for papermaking according to any one of [1] to [4], wherein the first polymerization component and/or the second polymerization component contains an anionic polymerizable monomer.

The invention [6] comprises the method for producing a (meth) acrylamide-based polymer additive for papermaking according to any one of the above [1] to [5], wherein the first polymerization component and/or the second polymerization component contains a nitrogen-containing crosslinkable monomer, and the nitrogen-containing crosslinkable monomer in the first polymerization component is 0.1 mol or less based on 100 mol of (meth) acrylamide in the first polymerization component.

The invention [7] is the process for producing the (meth) acrylamide polymer additive for papermaking according to [6], wherein the second polymerization component contains a nitrogen-containing crosslinkable monomer.

The invention [8] is directed to the method for producing the (meth) acrylamide polymer additive for papermaking according to any one of [1] to [7], wherein the first polymerization component and/or the second polymerization component further contains another polymerizable monomer.

The invention [9] is a method for producing the (meth) acrylamide polymer additive for papermaking according to any one of [1] to [8], wherein the polymerization component is subjected to multistage polymerization in the first polymerization step and/or the second polymerization step.

The invention [10] comprises a (meth) acrylamide polymer additive for papermaking obtained by polymerizing a polymerization component containing (meth) acrylamide, a tertiary amino monomer and (meth) allylsulfonic acid salt,

first, a first polymer is obtained by polymerizing a first polymerization component containing (meth) acrylamide,

thereafter polymerizing a second polymerization monomer containing the tertiary amino monomer in the presence of the first polymer to obtain a polymer;

said first polymeric component and/or said second polymeric component comprises said (meth) allylsulfonic acid salt,

the tertiary amino monomer in the first polymerization component is 0.1 mol or less based on 100 mol of (meth) acrylamide in the first polymerization component, and the (meth) acrylamide in the second polymerization component is 1.0 mol or less based on 100 mol of the tertiary amino monomer in the second polymerization component.

Effects of the invention

According to the method for producing the (meth) acrylamide polymer additive for papermaking of the present invention, the (meth) acrylamide polymer additive for papermaking can be produced favorably, and when used for papermaking, the content of (meth) acrylamide in the obtained paper product can be reduced while maintaining the performance as an additive for papermaking.

In addition, the (meth) acrylamide polymer additive for papermaking according to the present invention can reduce the content of (meth) acrylamide in the resulting paper product while maintaining the performance as an additive for papermaking when used for papermaking.

Detailed Description

According to the method for producing the additive for producing a (meth) acrylamide polymer to be used for papermaking of the present invention, a (meth) acrylamide polymer is produced by polymerizing a polymerization component containing (meth) acrylamide, a tertiary amino monomer and a (meth) allylsulfonic acid salt. That is, the (meth) acrylamide polymer is a polymer containing a polymerization component of (meth) acrylamide, a tertiary amino monomer, and (meth) allylsulfonic acid salt.

In this method, first, a part of the polymerization component (first polymerization component) is polymerized, and then the remaining part of the polymerization component (second polymerization component) is polymerized to produce a (meth) acrylamide polymer.

Among the polymerization components, acrylamide and methacrylamide may be mentioned as the (meth) acrylamide. The term (meth) acrylic acid is defined as acrylic acid and/or methacrylic acid (the same applies hereinafter).

The (meth) acrylamide may be used alone or in combination of 2 kinds. That is, either acrylamide or methacrylamide may be used alone or in combination. Preferably, acrylamide is used alone.

The content of (meth) acrylamide is, for example, 50 mol% or more, preferably 60 mol% or more, for example 99 mol% or less, preferably 97 mol% or less, based on the total moles of the polymerization components.

The tertiary amino monomer is a polymerizable monomer (non-quaternary ammonium salt) having a tertiary amino group, and examples thereof include a (meth) acrylate derivative having a tertiary amino group, a (meth) acrylamide derivative having a tertiary amino group, and the like.

Examples of the tertiary amino group-containing (meth) acrylate derivative include dialkylaminoethyl (meth) acrylate (e.g., dimethylaminoethyl (meth) acrylate), and dialkylaminopropyl methacrylate. Examples of the tertiary amino group-containing (meth) acrylamide derivative include dialkylaminoalkyl (meth) acrylamides (e.g., dialkylaminopropyl (meth) acrylamides (e.g., dimethylaminopropyl acrylamide), and (meth) acrylamido-3-methylbutyldimethylamine).

These tertiary amino monomers may be used alone or in combination of 2 or more.

The tertiary amino monomer preferably includes dialkylaminoethyl (meth) acrylate and dialkylaminoalkyl (meth) acrylamide, and more preferably includes dimethylaminoethyl (meth) acrylate and dimethylaminopropylacrylamide.

The content of the tertiary amino monomer is, for example, 0.01 mol% or more, preferably 0.1 mol% or more, for example, 15 mol% or less, preferably 10 mol% or less, based on the total moles of the polymerization components.

The (meth) allylsulfonate is also a copolymerizable monomer that acts as a chain transfer agent, and the term (meth) allyl is defined as allyl and/or methallyl.

Specific examples of the (meth) allylsulfonate include sodium allylsulfonate, sodium methallylsulfonate, potassium allylsulfonate, and potassium methallylsulfonate.

These (meth) allylsulfonic acid salts may be used alone or in combination of 2 or more.

As the (meth) allylsulfonic acid salt, sodium methallylsulfonate is preferably cited.

The content of the (meth) allylsulfonic acid salt is, for example, 0.01 mol% or more, preferably 0.2 mol% or more, for example, 5 mol% or less, preferably 3 mol% or less, based on the total mol of the polymerization components.

The polymerization component may contain a quaternary ammonium salt monomer as an optional component.

The quaternary ammonium salt monomer is a cationic copolymerizable monomer having a quaternary ammonium group and an ethylenic double bond, and examples thereof include a quaternary ammonium salt product obtained by quaternizing a tertiary amino group in a polymerizable monomer having a tertiary amino group (hereinafter referred to as a quaternary ammonium salt product of a tertiary amino monomer), a quaternary ammonium salt product obtained by quaternizing a tertiary amino group in a diallylamine derivative monomer (hereinafter referred to as a quaternary ammonium salt product of a diallylamine derivative monomer), and the like.

Examples of quaternary ammonium salt products of the tertiary amino monomer include quaternary ammonium salt products (quaternary ammonium salts) obtained by quaternizing the tertiary amino group in the tertiary amino monomer (polymerizable monomer having a tertiary amino group) with methyl chloride (methyl chloride), methyl bromide, benzyl chloride (benzyl chloride), benzyl bromide, dimethyl sulfate, epichlorohydrin, and the like.

Examples of the quaternary ammonium salt-formed product of the diallylamine derivative monomer include diallyldimethylammonium chloride, diallyldimethylammonium bromide, diallyldiethylammonium chloride, diallyldibutylammonium chloride, and diallylmethylethylammonium chloride.

These quaternary ammonium salt monomers may be used alone or in combination of 2 or more.

As the quaternary ammonium salt-based monomer, preferably, a quaternary ammonium salt-formed product of dialkylaminoalkyl (meth) acrylamide, a quaternary ammonium salt-formed product of a diallylamine derivative monomer, and more preferably, a quaternary ammonium salt-formed product of a diallylamine derivative monomer can be cited.

As quaternary ammonium salt products of dialkylaminoalkyl (meth) acrylamides, preference is given to quaternary ammonium salt products of dimethylaminopropyl acrylamide. In addition, preference is given to quaternary ammonium salification products which result from methyl chloride (methyl chloride) or benzyl chloride (benzyl chloride).

As quaternary ammonium salination products of diallylamine derivative monomers, preferably, diallyldimethylammonium chloride can be cited.

When the quaternary ammonium salt monomer is contained in the polymerization component, the content thereof is, for example, 0.01 mol% or more, preferably 0.1 mol% or more, for example, 50 mol% or less, preferably 40 mol% or less, more preferably 30 mol% or less, and further preferably 15 mol% or less, based on the total mol of the polymerization component.

The polymerizable component may contain an anionic polymerizable monomer as an optional component.

Examples of the anionic polymerizable monomer include organic acid monomers such as α -unsaturated carboxylic acid and sulfonic acid monomers having a vinyl group.

Examples of the α -unsaturated carboxylic acid include α -unsaturated monocarboxylic acid monomers such as acrylic acid, methacrylic acid and crotonic acid, and α -unsaturated dicarboxylic acid monomers such as maleic acid, fumaric acid, itaconic acid and citraconic acid.

Examples of the sulfonic acid monomer having a vinyl group include vinylsulfonic acid, styrenesulfonic acid, and 2-acrylamido-2-methylpropanesulfonic acid.

Further, as the anionic copolymerizable monomer, salts such as sodium salt, potassium salt, and ammonium salt of the above organic acid-based monomer can be used.

These anionic polymerizable monomers may be used alone or in combination of 2 or more.

The anionic polymerizable monomer is preferably an organic acid monomer, more preferably α -unsaturated carboxylic acid, and still more preferably itaconic acid or acrylic acid.

When the polymerizable component contains the anionically polymerizable monomer, the content thereof is, for example, 0.1 mol% or more, preferably 0.5 mol% or more, for example, 20 mol% or less, preferably 10 mol% or less, based on the total mol of the polymerizable component.

When the polymerizable component contains an anionic polymerizable monomer, the (meth) acrylamide polymer obtained from the polymerizable component can be used for paper making, and the content of (meth) acrylamide in the paper product can be reduced while the paper strength is further enhanced.

The polymerizable component may contain a nitrogen-containing crosslinkable monomer as an optional component.

The nitrogen-containing crosslinkable monomer is a crosslinkable monomer containing 1 or more nitrogen atoms in 1 molecule, and examples thereof include an amide group-containing crosslinkable monomer and an imide group-containing crosslinkable monomer.

Examples of the amide group-containing crosslinkable monomer include methylene bis (meth) acrylamide, ethylene bis (meth) acrylamide, allyl (meth) acrylamide, N-substituted acrylamide monomers (e.g., N' -dimethylacrylamide, diacetone acrylamide, isopropyl acrylamide), and formaldehyde triacrylate.

Examples of the imide group-containing crosslinkable monomer include diacrylimide and the like.

These nitrogen-containing crosslinkable monomers may be used alone or in combination of 2 or more.

When the nitrogen-containing crosslinkable monomer is contained in the polymerizable component, the content thereof is, for example, 0.01 mol% or more, preferably 0.02 mol% or more, more preferably 0.1 mol% or more, further preferably 0.5 mol% or more, for example, 20 mol% or less, preferably 10 mol% or less, more preferably 5 mol% or less, and further preferably 1 mol% or less, based on the total mol of the polymerizable component.

The polymerizable component may contain, as an optional component, another polymerizable monomer (polymerizable monomer other than (meth) acrylamide, tertiary amino monomer, (meth) allylsulfonate, quaternary ammonium salt monomer, anionic polymerizable monomer, and nitrogen-containing crosslinkable monomer).

Examples of the other polymerizable monomer include nonionic copolymerizable monomers.

Examples of the nonionic copolymerizable monomer include alkyl (meth) acrylate, hydroxyalkyl (meth) acrylate, diacetone acrylamide, styrene, α -methylstyrene, polyalkylene glycol (meth) acrylate, glycerol mono (meth) acrylate, vinylpyrrolidoneOxazoline, vinyl acetate, acryloylmorpholine, acrylic nitrile and the like, and preferable examples thereof include alkyl (meth) acrylate and hydroxyalkyl (meth) acrylate.

Examples of the alkyl (meth) acrylate include methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, isopropyl (meth) acrylate, n-butyl (meth) acrylate, isobutyl (meth) acrylate, sec-butyl (meth) acrylate, tert-butyl (meth) acrylate, pentyl (meth) acrylate, neopentyl (meth) acrylate, isoamyl (meth) acrylate, hexyl (meth) acrylate, heptyl (meth) acrylate, octyl (meth) acrylate, isooctyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, nonyl (meth) acrylate, isononyl (meth) acrylate, decyl (meth) acrylate, dodecyl (meth) acrylate, tridecyl (meth) acrylate, tetradecyl (meth) acrylate, and mixtures thereof, And linear, branched or cyclic alkyl (meth) acrylate monomers having 1 to 30 carbon atoms such as 1-methyltrodecyl (meth) acrylate, hexadecyl (meth) acrylate, octadecyl (meth) acrylate ((stearyl (meth) acrylate), isostearyl (meth) acrylate, eicosyl (meth) acrylate, behenyl (meth) acrylate, ditetradecyl (meth) acrylate, eicosyl (meth) acrylate, and cyclohexyl (meth) acrylate.

Examples of the hydroxyalkyl (meth) acrylate include 2-hydroxyethyl (meth) acrylate and 2-hydroxypropyl (meth) acrylate.

When the polymerizable component contains a nonionic copolymerizable monomer, the content thereof is, for example, 0.1 mol% or more, preferably 1 mol% or more, for example, 20 mol% or less, preferably 10 mol% or less, based on the total mol of the polymerizable component.

Further, as the other copolymerizable monomer, a nitrogen-free crosslinkable monomer can be mentioned.

The nitrogen-free crosslinkable monomer is a crosslinkable monomer containing no nitrogen atom in 1 molecule, and examples thereof include crosslinkable monomers containing no amide group and no imide group.

More specifically, examples of the nitrogen-free crosslinkable monomer include a nitrogen-free bifunctional crosslinking agent (e.g., divinylbenzene, ethylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, triethylene glycol di (meth) acrylate, allyl (meth) acrylate, etc.), a nitrogen-free polyfunctional crosslinking agent (e.g., pentaerythritol triacrylate, trimethylolpropane acrylate, tetraallyloxyethane, etc.), and the like.

These nitrogen-free crosslinkable monomers may be used alone or in combination of 2 or more.

When the nitrogen-free crosslinkable monomer is contained in the polymerizable component, the content thereof is, for example, 0.001 mol% or more, preferably 0.01 mol% or more, for example 10 mol% or less, preferably 5 mol% or less, based on the total mol of the polymerizable component.

The other polymerizable monomers may be used alone or in combination of 2 or more.

When the polymerizable component contains another polymerizable monomer, the (meth) acrylamide polymer obtained from the polymerizable component can be used for paper making, and the content of (meth) acrylamide in the paper product can be reduced while the paper strength can be further enhanced.

The polymerization component preferably contains (meth) acrylamide, a tertiary amino monomer, (meth) allylsulfonate, and at least 1 selected from the group consisting of a quaternary ammonium salt monomer, an anionic polymerizable monomer, a nitrogen-containing crosslinkable monomer, and another polymerizable monomer (preferably, an alkyl (meth) acrylate).

More preferably, the polymerizable components include polymerizable components comprising (meth) acrylamide, a tertiary amino monomer, and a (meth) allylsulfonate, polymerizable components comprising (meth) acrylamide, a tertiary amino monomer, a (meth) allylsulfonate, and a quaternary ammonium salt monomer, polymerizable components comprising (meth) acrylamide, a tertiary amino monomer, a (meth) allylsulfonate, and an anionic polymerizable monomer, and polymerizable components comprising (meth) acrylamide, a tertiary amino monomer, a (meth) allylsulfonate, a quaternary ammonium salt monomer, and an anionic polymerizable monomer.

In the method for producing the (meth) acrylamide polymer additive for papermaking, the polymerization components are first divided into a first polymerization component (a part of the polymerization components) containing (meth) acrylamide and a second polymerization component (the remaining part of the polymerization components) containing a tertiary amino monomer.

The first polymerization component is, for example, 1 mol% or more, preferably 3 mol% or more, for example, 99.5 mol% or less, and preferably 99 mol% or less, based on the total amount of the polymerization components (the total amount of the first polymerization component and the second polymerization component).

The second polymerization component is, for example, 0.5 mol% or more, preferably 1 mol% or more, for example 99 mol% or less, preferably 97 mol% or less, more preferably 50 mol% or less, and still more preferably 30 mol% or less, based on the total amount of the polymerization components (the total amount of the first polymerization component and the second polymerization component).

The first polymerization component contains (meth) acrylamide as an essential component.

The content of the (meth) acrylamide in the first polymerization component is, for example, 1 mol% or more, preferably 3 mol% or more, for example, 100 mol% or less, preferably 99.5 mol% or less, and more preferably 99 mol% or less, based on the total amount of the first polymerization component.

The first polymerization component does not contain a tertiary amino monomer, or contains a small amount of a tertiary amino monomer.

The content of the tertiary amino monomer in the first polymerization component is 0.1 mol or less, preferably 0.01 mol or less, and more preferably 0 mol based on 100 mol of (meth) acrylamide in the first polymerization component, from the viewpoint of reducing the content of (meth) acrylamide in the paper product.

That is, the first polymerization component preferably does not contain a tertiary amino monomer. The following description will discuss a formulation in which the first polymerization component does not contain a tertiary amino monomer.

The second polymerization component is obtained by removing the remaining part of the first polymerization component from the polymerization components, and contains a tertiary amino monomer as an essential component.

The content of the tertiary amino monomer in the second polymerization component is, for example, 0.5 mol% or more, preferably 0.1 mol% or more, for example, 100 mol% or less, preferably 95 mol% or less, and more preferably 90 mol% or less, based on the total amount of the second polymerization component.

In addition, the second polymeric component contains no (meth) acrylamide, or slightly (meth) acrylamide.

The content of (meth) acrylamide in the second polymerization component is 1.0 mol or less, preferably 0.1 mol or less, and more preferably 0 mol based on 100 mol of the tertiary amino monomer in the second polymerization component, from the viewpoint of reducing the content of (meth) acrylamide in the paper product.

That is, the second polymeric component preferably does not contain (meth) acrylamide. The following description will discuss a formulation in which the second polymerization component does not contain (meth) acrylamide.

Among the above-mentioned polymerization components, polymerization components other than the (meth) acrylamide and the tertiary amino monomer may be contained in the first polymerization component, the second polymerization component, and both of them.

Specifically, the (meth) allylsulfonic acid salt contained as an essential component in the polymerization component may be contained in the first polymerization component, may be contained in the second polymerization component, or may be contained in both of them. That is, the first polymeric component and/or the second polymeric component comprises a (meth) allylsulfonate salt.

Preferably, the (meth) allylsulfonate salt is contained in the first polymeric component alone or in both the first and second polymeric components.

The content ratio of the (meth) allylsulfonic acid salt in the first polymerization component and the content ratio of the (meth) allylsulfonic acid salt in the second polymerization component can be appropriately set according to the purpose and use.

In addition, each arbitrary component in the polymerization components may be contained in the first polymerization component, or may be contained in the second polymerization component, and further may be contained in both of them.

More specifically, when the polymerization component contains a quaternary ammonium salt monomer as an optional component, the quaternary ammonium salt monomer may be contained in the first polymerization component, may be contained in the second polymerization component, or may be contained in both of them. Preferably, the quaternary ammonium salt-based monomer is contained in the first polymerization component.

In the case where the polymerizable component contains an anionic polymerizable monomer as an optional component, the anionic polymerizable monomer may be contained in the first polymerizable component, may be contained in the second polymerizable component, or may be contained in both of them. Preferably, the anionic polymerizable monomer is contained in the first polymerizable component.

In addition, for example, in the case where the polymerizable component contains a nitrogen-containing crosslinkable monomer as an arbitrary component, the nitrogen-containing crosslinkable monomer may be contained in the first polymerizable component, may be contained in the second polymerizable component, or may be contained in both of them. Preferably, the nitrogen-containing crosslinkable monomer is contained in the second polymerizable component.

In other words, it is preferable that the second polymeric component contains a nitrogen-containing crosslinkable monomer. Further, the first polymerization component preferably does not contain a nitrogen-containing crosslinkable monomer or contains a small amount of a nitrogen-containing crosslinkable monomer.

The content of the nitrogen-containing crosslinkable monomer in the first polymerizable component is, for example, 0.1 mol or less, preferably 0.01 mol or less, and more preferably 0 mol based on 100 mol of (meth) acrylamide in the first polymerizable component, from the viewpoint of reducing the content of (meth) acrylamide in the paper product.

In addition, for example, in the case where the polymerizable component contains another polymerizable monomer as an arbitrary component, the other polymerizable monomer may be contained in the first polymerizable component, may be contained in the second polymerizable component, or may be contained in both of them. Preferably, the other polymerizable monomer is contained in the first polymerizable component.

Hereinafter, the case where the polymerization components contain (meth) acrylamide, a tertiary amino monomer, and (meth) allylsulfonic acid salt as essential components, and further contain a quaternary ammonium salt monomer as an optional component will be described in further detail.

In this case, the types and the content ratios (the fineness of the monomers) of the monomers of the first polymerization component and the second polymerization component may be in any of the following modes.

[ TABLE 1]

TABLE 1

In the table, "first" indicates a first polymerization component, and "second" indicates a second polymerization component, "AM" indicates (meth) acrylamide, "tertiary amine" indicates a tertiary amino monomer, "quaternary ammonium" indicates a quaternary ammonium salt monomer, "salt" indicates (meth) allylsulfonate, ○ "indicates incorporation, and" - "indicates incorporation (the same applies hereinafter).

In the above table 1, the first polymerization component is composed of (meth) acrylamide, a quaternary ammonium salt monomer and (meth) allylsulfonic acid salt, and the second polymerization component is composed of a tertiary amino monomer, as shown in the formula 1. In addition, the mode 2 shows a formula in which the first polymerization component is composed of a (meth) acrylamide monomer and a quaternary ammonium salt monomer, and the second polymerization component is composed of a tertiary amino monomer and a (meth) allylsulfonate.

In this method, first, only the first polymerization component (a part of the polymerization component) is polymerized to obtain a polymer body of the first polymerization component (first polymer body) (first polymerization step).

In the first polymerization step, in order to polymerize the first polymerization component, for example, the first polymerization component, a polymerization initiator, and a solvent are charged into a predetermined reaction vessel and reacted. In this method, the first polymerization component may be added together or may be added in portions. In addition, the reaction may be allowed to proceed while a part or all of the polymerization initiator is added dropwise into the reaction vessel.

The polymerization initiator includes, for example, a radical polymerization initiator, specifically, a peroxide-based compound, a sulfide-based compound, a sulfoxide-based compound, a sulfinic acid-based compound, and more preferably, a peroxide-based compound. The peroxide-based compound may be used as a redox-based polymerization initiator in combination with a reducing agent.

Examples of the peroxide-based compound include organic peroxides and inorganic peroxides, and inorganic peroxides are preferable.

Examples of the organic peroxide include benzoyl peroxide, lauroyl peroxide, acetyl peroxide, octanoyl peroxide (カプリエルパーオキサイド), 2, 4-dichlorobenzoyl peroxide, isobutyl peroxide, acetylcyclohexylsulfonyl peroxide, tert-butyl peroxydibutyrate, tert-butyl-2-ethylhexanoate peroxide, 1-di-tert-butylperoxycyclohexane, 1-di-tert-butylperoxy-3, 3, 5-trimethylcyclohexane, 1-di-tert-butylhexylperoxy-3, 3, 5-trimethylcyclohexane, isopropyl peroxydicarbonate, isobutyl peroxydicarbonate, sec-butyl peroxydicarbonate, n-butyl peroxydicarbonate, 2-ethylhexyl peroxydicarbonate, bis (4-tert-butylcyclohexyl) peroxydicarbonate, di-tert-butylcyclohexyl) peroxydicarbonate, and mixtures thereof, Tert-amyl peroxy-2-ethylhexanoate, 1,3, 3-tetramethylbutyl peroxy ethyl hexanoate, 1, 2-trimethylpropyl peroxy-2-ethylhexanoate, tert-butyl peroxy isopropyl monocarbonate, tert-amyl peroxy isopropyl monocarbonate, tert-butyl peroxy-2-ethylhexyl monocarbonate, tert-butyl peroxy allyl monocarbonate, t-butylperoxyisopropyl monocarbonate, 1,3, 3-tetramethylbutylperoxyisopropyl monocarbonate, 1, 2-trimethylpropylperoxyisopropyl monocarbonate, 1,3, 3-tetramethylbutylperoxyisononanoate, 1, 2-trimethylpropylperoxyisononanoate, t-butylperoxybenzoate and the like.

Examples of the inorganic peroxide include persulfates such as sodium persulfate, potassium persulfate, and ammonium persulfate, bromates such as hydrogen peroxide, potassium permanganate, sodium bromate, and potassium bromate, perborates such as sodium perborate, potassium perborate, and ammonium perborate, percarbonates such as sodium percarbonate, potassium percarbonate, and ammonium percarbonate, perphosphates such as sodium polyphosphate, potassium perphosphate, and ammonium perphosphate, and preferably include persulfates, more preferably include potassium persulfate, and ammonium persulfate, and still more preferably include ammonium persulfate.

These polymerization initiators may be used alone or in combination of 2 or more.

Further, as the polymerization initiator, an azo compound can be used.

Examples of the azo compound include 2,2 '-azobisisobutyronitrile, 2' -azo (2-methylpropylamidine), and salts thereof.

The polymerization initiator is preferably an inorganic peroxide, more preferably a persulfate, and still more preferably ammonium persulfate.

The use of a persulfate as a polymerization initiator, that is, the copolymerization of the first polymerization component in the presence of a persulfate, can provide a papermaking chemical having good operability.

The mixing ratio of the polymerization initiator is, for example, 0.01 parts by mass or more, preferably 0.05 parts by mass or more, for example, 10 parts by mass or less, preferably 5 parts by mass or less, relative to 100 parts by mass of the total amount of the first polymerization components.

Examples of the solvent include water, ketone solvents such as acetone and methyl ethyl ketone, monohydric alcohol solvents such as methanol, ethanol, propanol, isopropanol and butanol, glycol ether solvents such as ethylene glycol monoethyl ether and propylene glycol monomethyl ether, and ester ether solvents such as propylene glycol monomethyl ether acetate, which can be mixed with water. When tap water is used as the solvent, a chelating agent (e.g., ethylenediaminetetraacetic acid) may be added in an appropriate ratio to remove metals.

These solvents may be used alone or in combination of 2 or more.

As the solvent, water is preferably cited.

When water is used as the solvent, the (meth) acrylamide polymer is obtained as an aqueous solution thereof. When a solvent other than water is used, the (meth) acrylamide polymer is obtained as a dispersion thereof.

When the aqueous solution of the (meth) acrylamide polymer obtained by using water as a solvent is used for the production of paper, the content of (meth) acrylamide in the paper product can be more favorably reduced.

The blending ratio of the solvent is not particularly limited, and may be appropriately set according to the purpose and use.

In this method, a chain transfer agent (other than (meth) allyl sulfonate) may be further appropriately added together with the first polymerization component, the polymerization initiator, and the solvent.

Examples of the chain transfer agent include isopropyl alcohol, for example, mercapto group compounds (for example, mercaptoethanol, thiourea, mercaptoacetic acid, mercaptopropionic acid, mercaptosalicylic acid, mercaptolactic acid, aminoethanethiol, mercaptoglycerol, thiomalic acid, etc.), and the like.

These chain transfer agents may be used alone or in combination of 2 or more.

The proportion of the chain transfer agent is, for example, 0.05 mol% or more, preferably 0.1 mol% or more, for example 10 mol% or less, preferably 5 mol% or less, relative to the total number of moles of the first polymerization component.

The polymerization conditions in the first polymerization step vary depending on the kind of the first polymerization component, the polymerization initiator, the solvent, and the like, but the polymerization temperature is, for example, 30 ℃ or more, preferably 50 ℃ or more, for example, 100 ℃ or less, preferably 95 ℃ or less.

The polymerization time is, for example, 0.5 hours or more, preferably 1 hour or more, for example, 24 hours or less, preferably 12 hours or less.

The pH of the reaction solution during polymerization is, for example, 1 or more, preferably 2 or more, and is, for example, 6 or less, preferably 5 or less. The pH can be adjusted by adding a known acid such as hydrochloric acid, sulfuric acid, or phosphoric acid.

By such a polymerization reaction, a solution containing the first polymer can be obtained.

In the first polymerization step, if necessary, a known polymerization terminator (e.g., sodium sulfite) may be added to stop the polymerization reaction. Preferably, the resulting solution (solution containing the first polymer) is supplied directly to the second polymerization step described later after the first polymerization step without stopping the polymerization reaction.

In addition, the solution obtained in the first polymerization step preferably contains no unreacted (meth) acrylamide or a trace amount of the first polymerization component.

The content of the unreacted (meth) acrylamide in the solution obtained in the first polymerization step is 0.1 mol% or less, preferably 0.01 mol% or less, and particularly preferably 0 mol% with respect to the first polymer. That is, the solution obtained in the first polymerization step is preferably free from unreacted (meth) acrylamide.

The content of unreacted (meth) acrylamide can be measured in accordance with the examples described later. If necessary, the solution obtained in the first polymerization step may be purified by a known method such as distillation or extraction, whereby the content of unreacted (meth) acrylamide can be reduced.

In this method, the second polymerization molecule is polymerized in the presence of the first polymer obtained in the first polymerization step to obtain a (meth) acrylamide polymer (second polymerization step).

In order to polymerize the second polymerization component, for example, the second polymerization component is added to the solution (containing the first polymer) obtained in the first polymerization step, and the solution is reacted. Further, the polymerization initiator, the solvent, the chain transfer agent, and the like may be further added as necessary.

In this method, the second polymerization components may be added together or may be added in portions.

The polymerization conditions in the second polymerization step vary depending on the kind of the second polymerization component, and the polymerization temperature is, for example, 30 ℃ or more, preferably 50 ℃ or more, for example, 100 ℃ or less, preferably 95 ℃ or less.

The polymerization time is, for example, 0.5 hours or more, preferably 1 hour or more, for example, 24 hours or less, preferably 12 hours or less.

The pH of the reaction solution during polymerization is, for example, 1 or more, preferably 2 or more, and is, for example, 6 or less, preferably 5 or less. The pH can be adjusted by adding a known acid such as hydrochloric acid, sulfuric acid, or phosphoric acid.

The polymerization reaction in the second polymerization step can be usually stopped by adding a known polymerization terminator (for example, sodium sulfite or the like).

By such a polymerization reaction, the (meth) acrylamide polymer additive for papermaking can be obtained as a solution (preferably an aqueous solution) of the (meth) acrylamide polymer.

In the additive for papermaking of a (meth) acrylamide polymer, the concentration of the (meth) acrylamide polymer is, for example, 10 mass% or more, preferably 20 mass% or more, and is, for example, 50 mass% or less, preferably 45 mass% or less.

The weight average molecular weight of the (meth) acrylamide polymer is, for example, 150 ten thousand or more, preferably 300 ten thousand or more, for example 1500 ten thousand or less, preferably 1000 ten thousand or less.

The weight average molecular weight of the (meth) acrylamide polymer can be appropriately adjusted depending on, for example, the type and amount of the polymerization component.

The method for measuring the weight average molecular weight is performed in accordance with examples described later.

The viscosity of the solution of the (meth) acrylamide polymer (nonvolatile content (solid content) 20 mass% (25 ℃ C.)) is, for example, 100 mPs or more, preferably 1000 mPs or more, for example, 50000 mPs or less, preferably 20000 mPs or less.

The viscosity was measured according to the examples described below.

In the method for producing the additive for papermaking of a (meth) acrylamide polymer, in the first polymerization step, (meth) acrylamide is polymerized, and the tertiary amino monomer is hardly (or not at all) polymerized. On the other hand, in the second polymerization step, the tertiary amino-based monomer is polymerized in an environment where the (meth) acrylamide is almost (or completely) absent.

Therefore, according to the method for producing a (meth) acrylamide polymer additive for papermaking, a (meth) acrylamide polymer additive for papermaking can be produced favorably, and when the additive is used for papermaking, the content of (meth) acrylamide in the obtained paper product can be reduced while maintaining the performance as an additive for papermaking.

In addition, the (meth) acrylamide polymer additive for papermaking obtained by the above method can reduce the content of (meth) acrylamide in the obtained paper product while maintaining the performance as an additive for papermaking when used for papermaking.

In the above method, the first polymerization component is polymerized in 1 stage in the first polymerization step, and thereafter the second polymerization component is polymerized in 1 stage in the second polymerization step, but the polymerization component may be polymerized in multiple stages in the first polymerization step and/or the second polymerization step.

Preferably, the first polymeric component is polymerized in a first polymerization step in multiple stages and/or the second polymeric component is polymerized in a second polymerization step in multiple stages.

When the first polymerization component is subjected to multistage polymerization, the number of steps is not particularly limited, and may be, for example, 2 or more, for example, 4 or less, preferably 3 or less, and particularly preferably 2.

When the second polymerization is carried out in multiple stages, the number of steps is not particularly limited, and may be, for example, 2 stages or more, for example, 4 stages or less, preferably 3 stages or less, and particularly preferably 2 stages.

Particularly preferably, in the first polymerization step, the first polymerization component is polymerized in multiple stages (preferably, 2-stage polymerization), and in the second polymerization step, the second polymerization step is not polymerized in multiple stages but 1-stage polymerization.

When the first polymerization component is polymerized in 2 stages and the second polymerization component is polymerized in 1 stage, the polymerization components are polymerized in 3 stages (hereinafter referred to as 3 stages of stage a, stage B and stage C) as a whole.

In this case, for example, the first polymerization component is divided into 2 parts (hereinafter, one is referred to as a first polymerization component a, and the other is referred to as a first polymerization component B).

In this case, the types and the content ratios of the monomers in the first polymerization component a and the first polymerization component B (the details of the monomers) may be the same or may be different from each other.

More specifically, for example, in the mode 1 in table 1, the first polymerization component contains a quaternary ammonium salt monomer and a (meth) allylsulfonic acid salt in addition to the (meth) acrylamide. When the first polymerization component is divided into the first polymerization component a and the first polymerization component B, the quaternary ammonium salt monomer and the (meth) allylsulfonic acid salt may be contained in at least one of the first polymerization component a and the first polymerization component B, or may be contained in both the first polymerization component a and the first polymerization component B.

In this case, the modes 1 to 9 described in table 1 are further divided into modes as shown in tables 2 to 10.

In the following description, "first-a" represents the first polymerization component a, and "first-B" represents the first polymerization component B.

[ TABLE 2]

TABLE 2

[ TABLE 3]

TABLE 3

[ TABLE 4]

TABLE 4

[ TABLE 5]

TABLE 5

[ TABLE 6]

TABLE 6

[ TABLE 7]

TABLE 7

[ TABLE 8]

TABLE 8

[ TABLE 9]

TABLE 9

[ TABLE 10]

Watch 10

The polymerization component may further contain a monomer (other than (meth) acrylamide, a tertiary amino monomer, (meth) allylsulfonate, and a quaternary ammonium salt monomer) not shown in tables 2 to 10. More specifically, for example, the polymerizable component may contain an anionic polymerizable monomer or the like.

In this case, the anionic polymerizable monomer may be contained in the first polymerizable component, or may be contained in the second polymerizable component, or may be contained in both of them.

In the case of multistage polymerization of the first polymerization component, an anionically polymerizable monomer may be contained in the polymerization component in any stage.

More specifically, in the case where the first polymerization component is polymerized in 2 stages in the first polymerization step and the second polymerization component is polymerized in 1 stage in the second polymerization step, the anionic polymerizable monomer may be contained in either one of the first polymerization component (the first polymerization component a, the first polymerization component B) and the second polymerization component or in a plurality of polymerization components.

As an example, in the case where the polymerizable component further contains an anionic polymerizable monomer in the mode 1(1) described in table 2, as shown in table 11, an anionic polymerizable monomer may be added to any one of the first polymerizable component (the first polymerizable component a, the first polymerizable component B) and the second polymerizable component.

In table 11, "negative ion" means an anionic polymerizable monomer. Although not described in detail, the same applies to other modes.

[ TABLE 11 ]

TABLE 11

In this method, first, the first polymerization component a is polymerized in the same manner as in the first polymerization step (first polymerization step a).

The polymerization conditions in the first polymerization step A are, for example, a polymerization temperature of 30 ℃ or higher, preferably 50 ℃ or higher, for example 100 ℃ or lower, preferably 95 ℃ or lower.

The polymerization time is, for example, 1 minute or more, preferably 3 minutes or more, for example 12 hours or less, preferably 6 hours or less.

In the first polymerization step a, the polymerization reaction can be stopped by adding a known polymerization terminator (for example, sodium sulfite) as necessary. Preferably, the solution obtained after the first polymerization step a is supplied directly to the first polymerization step B described later without stopping the polymerization reaction.

Next, the first polymerization component B is added to the solution obtained in the first polymerization step a to carry out a reaction (first polymerization step B).

The polymerization conditions in the first polymerization step B are, for example, a polymerization temperature of 30 ℃ or higher, preferably 50 ℃ or higher, for example 100 ℃ or lower, preferably 95 ℃ or lower.

The polymerization time is, for example, 1 minute or more, preferably 3 minutes or more, for example 12 hours or less, preferably 6 hours or less.

Thus, a solution (preferably an aqueous solution) containing the first polymer can be obtained by such a polymerization reaction.

Thereafter, in this method, a second polymerization component (hereinafter referred to as a second polymerization component C) is added to the solution (first polymer-containing solution) obtained in the first polymerization step B to cause a reaction (second polymerization step C).

In the polymerization conditions in the second polymerization step, the polymerization temperature is, for example, 30 ℃ or more, preferably 50 ℃ or more, for example, 100 ℃ or less, preferably 95 ℃ or less.

The polymerization time is, for example, 0.5 hours or more, preferably 1 hour or more, for example, 24 hours or less, preferably 12 hours or less.

In addition, the polymerization reaction in the second polymerization step is usually stopped by adding a known polymerization terminator (e.g., sodium sulfite, etc.).

Thus, a solution (preferably an aqueous solution) of the (meth) acrylamide polymer as the second polymer can be obtained.

In this way, when the polymerization components are polymerized in multiple stages in the first polymerization step and/or the second polymerization step (preferably in the first polymerization step), the molecular structure of the obtained (meth) acrylamide polymer can be controlled to a desired tendency, and a (meth) acrylamide polymer additive for papermaking that can enhance the paper strength more favorably and a (meth) acrylamide polymer additive for papermaking that can improve the productivity favorably can be obtained.

In the above description, the polymerization components are used as both the first polymerization component containing (meth) acrylamide and the second polymerization component containing a tertiary amino monomer, but for example, a third polymerization component containing neither (meth) acrylamide nor a tertiary amino monomer may be used.

In this case, the polymerization components are used in the form of a first polymerization component containing at least (meth) acrylamide, a second polymerization component containing at least a tertiary amino monomer, and a third polymerization component containing neither (meth) acrylamide nor a tertiary amino monomer.

In this case, the third component contains not (meth) acrylamide and a tertiary amino monomer but (meth) allylsulfonate and/or any component (e.g., a quaternary ammonium salt monomer, an anionic polymerizable monomer, a nitrogen-containing crosslinkable monomer, another polymerizable monomer, etc.).

The third polymerization component may be polymerized before the first polymerization step, may be polymerized between the first polymerization step and the second polymerization step, or may be polymerized after the second polymerization step. However, in the case where the third polymerization component contains a nitrogen-containing crosslinkable monomer, the third polymerization component is preferably polymerized after the first polymerization step.

In the above-mentioned method for producing an additive for papermaking of a (meth) acrylamide polymer, in the first polymerization step, (meth) acrylamide is polymerized, and the tertiary amino monomer is hardly (or not at all) polymerized. On the other hand, in the second polymerization step, the tertiary amino-based monomer is polymerized in an environment where the (meth) acrylamide is almost (or completely) absent.

Therefore, in the method for producing the (meth) acrylamide polymer additive for papermaking, the (meth) acrylamide polymer additive for papermaking can be produced favorably, and when the additive is used for papermaking, the content of (meth) acrylamide in the obtained paper product can be reduced while maintaining the performance as an additive for papermaking.

The (meth) acrylamide polymer additive for papermaking obtained by the method can reduce the content of (meth) acrylamide in the obtained paper product while maintaining the performance as an additive for papermaking when used for papermaking.

More specifically, the (meth) acrylamide polymer additive for papermaking is added to a pulp slurry, and papermaking is performed by wet papermaking. The wet papermaking method is not particularly limited, and a known method can be adopted, and the method can be widely used for various papermaking regardless of acid paper using aluminum sulfate as a color fixing agent or neutral paper using calcium carbonate as a filler. Further, paper obtained by wet papermaking includes newspaper, ink jet paper, thermal recording paper, pressure sensitive recording paper, fine paper, cardboard, coated paper, household paper, and other papers.

The mixing ratio of the (meth) acrylamide polymer additive for papermaking and the pulp slurry is not particularly limited, and the (meth) acrylamide polymer (solid content) is, for example, 0.001 parts by mass or more, preferably 0.005 parts by mass or more, for example, 5.0 parts by mass or less, and preferably 2.0 parts by mass or less, per 100 parts by mass of the pulp slurry.

Also, the paper thus obtained has good paper strength and/or good yield.

That is, the above-mentioned (meth) acrylamide polymer additive for papermaking can be suitably used as a paper strength enhancer and/or a yield increasing agent.

In addition, the (meth) acrylamide content of the paper obtained by using the (meth) acrylamide polymer additive for papermaking is reduced.

Specifically, the content of (meth) acrylamide in the paper is, for example, 0.2ppm or less, preferably 0.1ppm or less, as a numerical value obtained by extracting (meth) acrylamide and calculating the amount of (meth) acrylamide extracted per unit mass of paper according to examples described later.

Thus, the paper thus obtained can be suitably used as a food wrapping paper.

The present invention includes the invention of the (meth) acrylamide polymer as an additive for papermaking as described above.

Specifically, the present invention comprises polymerizing a first polymerization component containing at least (meth) acrylamide, and then polymerizing a second polymerization component containing at least a tertiary amino monomer in the presence of the obtained polymer to obtain a (meth) acrylamide-containing polymer additive for papermaking.

The additive for papermaking of (meth) acrylamide polymer is limited by the production method as described above.

However, as shown below, the additive for papermaking of a (meth) acrylamide polymer may not be directly limited or may not be directly limited in terms of its structure or characteristics.

That is, the (meth) acrylamide polymer is generally produced by radical polymerization. In such radical polymerization, while radical polymerization is performed between the respective monomers as raw materials of the (meth) acrylamide polymer, dehydrogenation is performed from the obtained (meth) acrylamide polymer (oligomer) with the progress of polymerization, and a polymerization reaction (radical addition) is started with the (meth) acrylamide polymer (oligomer) as a starting point.

Further, a polymerization reaction (radical addition) is started from the branched (meth) acrylamide polymer (oligomer) thus formed.

By repeating such polymerization reaction, the obtained (meth) acrylamide polymer has a complicated and various branched structure. Further, the reaction is not completed at the time of forming a specific branched structure, and a (meth) acrylamide polymer having an unspecified large number of branches is randomly formed as long as radicals continue to be generated by the radical polymerization initiator.

When such a (meth) acrylamide polymer is analyzed for a linear structure and/or a branched structure by a Gel Permeation Chromatography (GPC), a light scattering method, or the like, only the approximate size of the branch can be determined, and the structure and the characteristics thereof are not limited.

In addition, when a branch is formed, although it can be judged from the formulation of the reaction system with respect to the polymerization component (monomer component) present in the reaction system, the structure and the characteristics cannot be limited because covalent bonds are randomly formed between the (meth) acrylamide polymers to form a complicated branch structure.

As described above, the additive for papermaking of a (meth) acrylamide polymer is limited by the production method, but may not be directly limited or may not be directly limited in terms of its structure or characteristics.

In the present specification and claims, numerical values below the numerical values described below the decimal point are both referred to as 0.

More specifically, in the present specification and claims, for example, when a numerical value is described as being the first digit of decimal point or less (for example, 0.1), the numerical values at the second and subsequent digits of decimal point or less are both indicated as 0 (for example, 0.10).