JP3186377B2 - Papermaking additives - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a papermaking additive comprising an acrylamide copolymer having a branched structure obtained by polymerizing acrylamides and a vinyl monomer copolymerizable therewith in the presence of a silicon compound. It is.

[0002]

2. Description of the Related Art In the papermaking process, various papermaking additives have been used in order to improve the productivity with the speeding up of a paper machine or to improve the quality of paper. Above all,
Paper strength enhancers, drainage improvers, retention enhancers and the like are indispensable in papermaking as particularly important chemicals, and the range of use is further widened and chemicals are being improved. The reasons for this were that the use of virgin pulp was restricted due to the worsening log supply situation, the necessity of recycling waste paper for the purpose of energy saving and effective use of resources was further strengthened, and drainage regulations, etc. For example, the closed ratio of white water has increased, and the amount of impurities has increased.

[0003] As additives for papermaking, starch, epichlorohydrin modified polyamide polyamine, melamine formaldehyde resin, urea formaldehyde resin and acrylamide-based polymer mainly composed of acrylamide are used according to the purpose. Acrylamide polymers are most widely and generally used because of their synthetic advantages, performance, and ease of handling during use.

[0004] As papermaking additives comprising acrylamide-based polymers, there are anionic type,
The cation type and the amphoteric type are known. Examples of the anion type include a copolymer of acrylamides and a vinyl monomer having an anionic group and a partial hydrolyzate of a polyacrylamide polymer. Examples of the cationic type include a copolymer of acrylamides and a vinyl monomer having a cationic group, and a modified Hoffman- and Mannich-modified acrylamide polymer. Examples of the amphoteric type include acrylamides, a vinyl monomer having a cationic group and a vinyl monomer having an anionic group, a copolymer of a nonionic vinyl monomer which can be copolymerized as necessary, and a vinyl monomer having an acrylamide and an anionic group. Hoffman-modified product, Mannich-modified product and the like.

[0005] In order to enhance the paper strength effect as a papermaking additive and to exhibit the drainage and retention improvement effects,
It is necessary to reinforce the hydrogen bonds between the cellulose molecules in the pulp with an acrylamide-based polymer and to aggregate the cellulose fibers to some extent. However, in the papermaking industry in recent years, factors such as the deterioration of the raw material conditions of paper as described above, the increase in the amount of impurities in white water generated during the papermaking process, and the fluctuation of papermaking pH have been increasing. To these factors, a papermaking additive using an acrylamide-based polymer, which is known to have a relatively low molecular weight and is considered to have a nearly linear polymer form, has a sufficient effect. It is not currently done.

For this reason, various polyfunctional vinyl monomers have been used to impart a branched structure to the acrylamide-based polymer and increase the molecular weight. When a high molecular weight acrylamide polymer having a branched structure is used, paper strength and drainage are improved. This effect is thought to be due to the fact that by having a branched structure and increasing the molecular weight, the number of contact points between the acrylamide-based polymer and the pulp increased, the hydrogen bonds between cellulose molecules in the pulp increased, and the pulp agglomerated. It is.

[0007]

DISCLOSURE OF THE INVENTION The present invention relates to a novel polyfunctional compound capable of imparting superior paper strength and drainage compared with conventionally known polyacrylamide-based polymer papermaking additives having a relatively low molecular weight. An object of the present invention is to provide an acrylamide-based polymer papermaking additive using a hydrophilic crosslinking agent.

[0008]

The present inventors have conducted intensive studies to solve the above-mentioned problems, and as a result, unlike a known polyfunctional vinyl monomer, a novel additive not conventionally used in papermaking additives. We found a polyfunctional cross-linking agent consisting of a specific silicon compound and succeeded in imparting a branched structure to an acrylamide polymer.

That is, the present invention relates to acrylamides (a), a vinyl monomer (b) having an anionic group copolymerizable with the component (a), and a vinyl monomer (c) having a cationic group copolymerizable with the component (a). ), A silicon compound (d) containing at least one unit represented by the general formula (1) and at least one unit represented by the general formula (2), and if necessary, the component (a) It is intended to provide a papermaking additive comprising a copolymer obtained by polymerizing a nonionic vinyl monomer (e) copolymerizable with a papermaking additive.

[0010]

Embedded image [However, in the formula (1), R ¹ represents a hydrogen atom or a methyl group. ]

[0011]

Embedded image [Z is the same or different from the following formulas (3.1) to (3 ·
7) represents a group represented by any of the above. However, (3
The groups represented by 5) to (3.7) represent S represented by the formula (2)
Except when all three of Z bonded to i are occupied. ]

[0012]

Embedded image

In the formulas (3.1) to (3.7), X represents a halogen atom, and R ² and R ³ each independently represent a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, oxygen, nitrogen Or an alkyl group having 1 to 4 carbon atoms having a substituent containing halogen, a phenyl group or a phenyl group having a substituent containing oxygen, nitrogen or halogen, R ⁴ is a hydrogen atom, an alkyl group having 1 to 4 carbon atoms An alkyl group having 1 to 4 carbon atoms having a substituent containing oxygen, nitrogen or halogen, a phenyl group, a phenyl group or a benzyl group having a substituent containing oxygen, nitrogen or halogen, R ⁵
Represents a hydrogen atom or a methyl group].

In the present invention, the acrylamides (a) include acrylamide and methacrylamide, as well as N-methyl (meth) acrylamide, N-ethyl (meth) acrylamide, N, N-dimethyl (meth) acrylamide, N -Isopropyl (meth) acrylamide,
N-substituted acrylamides such as Nt-octyl (meth) acrylamide and the like can be mentioned, and these can be used alone or in combination of two or more.

Examples of the vinyl monomer (b) having an anionic group include monocarboxylic acids such as acrylic acid, methacrylic acid and crotonic acid; maleic acid, fumaric acid,
Dicarboxylic acids such as itaconic acid, muconic acid and citraconic acid; organic sulfonic acids such as vinyl sulfonic acid, styrene sulfonic acid, allyl sulfonic acid and 2-acrylamide-2-methylpropane sulfonic acid; or sodium salts of these various organic acids; Examples thereof include alkali metal salts such as potassium salts, ammonium salts and the like, and these may be used alone or in combination of two or more.

As the vinyl monomer (c) having a cationic group, for example, dimethylaminoethyl (meth)
Acrylate, diethylaminoethyl (meth) acrylate, dimethylaminopropyl (meth) acrylate,
Vinyl monomers having a tertiary amino group such as diethylaminopropyl (meth) acrylate, dimethylaminopropyl (meth) acrylamide or diethylaminopropyl (meth) acrylamide, allylamine, diallylamine, or inorganic compounds thereof such as hydrochloric acid, sulfuric acid, formic acid, and acetic acid Salts of acids or organic acids, or the tertiary amino group-containing vinyl monomer and alkyl chlorides such as methyl chloride and methyl bromide, arylalkyl halides such as benzyl chloride and benzyl bromide, dimethyl sulfate, diethyl sulfate, epichlorohydrin and the like. Vinyl monomer containing a quaternary ammonium salt obtained by reaction with a quaternizing agent and 2-hydroxy N, N, N,
N ', N'-pentamethyl-N'-[3-{(1-oxo-2-propenyl) amino} propyl] -1,3-propanediaminium dichloride, etc., and these may be used alone or in combination. These can be used together.

Examples of the silicon compound (d) containing at least one unit represented by the general formula (1) and at least one unit represented by the general formula (2) are as follows: A compound represented by the formula can be exemplified.

[0018]

Embedded image [However, in the formula (4), R ¹ is a hydrogen atom or a methyl group, Y is a —COO— group, a —CONR ⁷ — group (R ⁷ is a lower alkyl group), or a phenyl group, and R ⁶ is an alkylene group or a chain. Z represents a divalent organic residue in which carbon atoms are mutually bonded by oxygen or nitrogen, and Z represents the same or different groups represented by any of the following formulas (3.1) to (3.7). However, the case where the groups represented by (3.5) to (3.7) occupy all three of Z bonded to Si represented by the formula (4) is excluded. ]

[0019]

Embedded image

In the formulas (3.1) to (3.7), X represents a halogen atom, and R ² and R ³ are each independently a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, oxygen, nitrogen Or an alkyl group having 1 to 4 carbon atoms having a substituent containing halogen, a phenyl group or a phenyl group having a substituent containing oxygen, nitrogen or halogen, R ⁴ is hydrogen, an alkyl group having 1 to 4 carbon atoms, An alkyl group having 1 to 4 carbon atoms having a substituent containing oxygen, nitrogen or halogen,
A phenyl group, a phenyl group having a substituent containing oxygen, nitrogen or halogen, or a benzyl group, and R ⁵ represents a hydrogen atom or a methyl group].

The above-mentioned substituents containing oxygen, nitrogen or halogen include amino, nitro, N-alkylamino, N, N-dialkylamino, fluorine, chlorine, bromine, iodine and nitrile. Examples thereof include a group, an aldehyde group, and a hydroxyl group, and a chlorine atom, a nitro group, and an amino group are preferably used.

Specific examples include, for example, 3- (meth) acryloxymethyltrimethoxysilane, 3- (meth) acryloxypropyldimethoxymethylsilane, 3- (meth) acryloxypropyltrimethoxysilane,
(Meth) acryloxypropylmethyldichlorosilane,
3- (meth) acryloxyoctadecyltriacetoxysilane, 3- (meth) acryloxy-2,5-dimethylhexyldiacetoxymethylsilane, 3- (meth) acrylamidopropyltrimethoxysilane, 2- (meth)
Acrylamidoethyltrimethoxysilane, 1- (meth) acrylamidomethyltrimethoxysilane, 2-
(Meth) acrylamido-2-methylpropyltrimethoxysilane, 2- (meth) acrylamido-2-methylethyltrimethoxysilane, 2- (meth) acrylamidoisopropyltrimethoxysilane,

3- (meth) acrylamidopropyltriethoxysilane, N- (2- (meth) acrylamidoethyl) aminopropyltrimethoxysilane, (3- (meth) acrylamidopropyl) oxypropyltrimethoxysilane, 3- (N -Methyl (meth) acrylamido) propyltrimethoxysilane, 3-((meth) acrylamido-methoxy) -3-hydroxypropyltrimethoxysilane, 3-((meth) acrylamido-methoxy) propyltrimethoxysilane, 3- (vinyl) Benzylaminopropyl) trimethoxysilane, dimethyl-
3- (meth) acrylamido-propyl-3- (trimethoxysilyl) -propylammonium chloride, dimethyl-2- (meth) acrylamido-2-methylpropyl-3- (trimethoxysilyl) -propylammonium chloride,

3- (meth) acrylamidopropylmethyldimethoxysilane, 3- (meth) acrylamidopropyldimethylmethoxysilane, 3- (meth) acrylamidopropylisobutyldimethoxysilane, 2- (meth) acrylamidopropylisobutyldimethoxysilane, 2- ( (Meth) acrylamido-2-methylpropylmonochlorodimethoxysilane, 2- (meth) acrylamido-2-methylpropylhydrogendimethoxysilane, 3- (meth) acrylamidopropylbenzyldiethoxysilane, 3- (meth) acrylamidopropyltriacetoxysilane , 2- (meth) acrylamidoethyltriacetoxysilane, 4- (meth) acrylamidobutyltriacetoxysilane, 2- (meth) acrylamido-2-methyl B pills triacetoxy silane, N
-(2- (meth) acrylamidoethyl) aminopropyltriacetoxysilane,

2- (N-ethyl (meth) acrylamido) ethyltriacetoxysilane, 3- (meth) acrylamidopropyloctyldiacetoxysilane, 1-
(Meth) acrylamidomethylphenyldiacetoxysilane, 3- (meth) acrylamidopropyltripropionyloxysilane, 3- (meth) acrylamidopropyltri (N-methylaminoethoxy) silane, vinyltrichlorosilane, vinylmethyldichlorosilane, divinyldi Chlorosilane, vinylphenyldichlorosilane, vinyldimethylchlorosilane, vinylmethylphenylchlorosilane, vinyldiphenylchlorosilane, vinyltrimethoxysilane, vinylmethyldimethoxysilane, vinylisobutyldimethoxysilane, vinyldimethylmethoxysilane, vinyltriethoxysilane, 3-vinylbenzylamino Propyltriethoxysilane, vinylmethyldiethoxysilane, divinyldiethoxysilane,

Vinyl dimethyl ethoxy silane, vinyl diphenyl ethoxy silane, vinyl triisopropoxy silane, vinyl tributoxy silane, vinyl dimethyl isobutoxy silane, vinyl triphenoxy silane, vinyl dimethyl (3-aminophenoxy) silane, vinyl dimethyl (4- Aminophenoxy) silane, vinyldimethyl (3-methyl-4-chlorophenoxy) silane, vinyldimethyl (2-methyl-4-chlorophenoxy) silane, vinyltriacetoxysilane, vinylmethyldiacetoxysilane, vinyldimethylacetoxysilane, etc. Can be illustrated. In addition, the following compounds can be exemplified as the silicon compound (d). 3- (N-styrylmethyl-2-
Aminoethylamino) propyltrimethoxysilane hydrochloride,

[0027]

Embedded image In the above two compounds, n represents an integer of 1 to 4, and R represents an alkylene group having 1 to 10 carbon atoms. These may be used alone or in combination of two or more.

The silicon compound (d) is a component necessary for imparting a branched structure to the acrylamide polymer, and its reaction mechanism is considered as follows. Since the silicon compound (d) has an unsaturated group (carbon-carbon double bond), it is another monomer component (a),
It copolymerizes with (b), (c) and (e). Further, since the substituent Z bonded to silicon is hydrolyzable except for (3.5) to (3.7), most of the substituent Z in the aqueous system becomes silanol instead of a hydroxyl group. This silanol causes a dehydration reaction in a bimolecular reaction to form a siloxane bond. That is, it is considered that the acrylamide-based polymer of the present invention has a branched structure by a siloxane bond.

Further, if desired, in addition to the above constituent monomers, any nonionic vinyl monomer (e) copolymerizable therewith can be introduced. Examples of the nonionic vinyl monomer include an ester of an alcohol having 1 to 8 carbon atoms and acrylic acid or methacrylic acid,
Acrylonitrile, styrene, vinyl acetate, methyl vinyl ether and the like can be exemplified.

When the acrylamide polymer is produced, a so-called polyfunctional vinyl monomer may be used in addition to the components (a) to (e). Examples of the polyfunctional vinyl monomer include di (meth) acrylates such as ethylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, triethylene glycol di (meth) acrylate, and propylene glycol di (meth) acrylate; (Meta)
Acrylamide, ethylenebis (meth) acrylamide, hexamethylenebis (meth) acrylamide, N,
Bis (meth) acrylamides such as N'-bisacrylamidoacetic acid, methyl N, N'-bisacrylamidoacetate, N, N-benzylidenebisacrylamide, divinyl esters such as divinyl adipate and divinyl sebacate, epoxy acrylates;

Urethane acrylates, allyl (meth)
Acrylate, diallyl phthalate, diallyl malate, diallyl succinate, diallyl acrylamide,
Bifunctional vinyl monomers such as divinylbenzene, diisopropylbenzene, diallylamine, N, N-diallylmethacrylamide, N-methylolacrylamide, diallyldimethylammonium, diallylchlorendate and glycidyl (meth) acrylate; 1,3,5 Trifunctional vinyl monomers such as -triacryloylhexahydro-S-triazine, triallyl isocyanurate, N, N-diallylacrylamide, triallylamine, triallyl trimellitate; tetramethylolmethane tetraacrylate, tetraallyl pyromellitate; N,
Examples thereof include tetrafunctional vinyl monomers such as N, N ', N'-tetraallyl-1,4-diaminobutane, tetraallylamine salt, and tetraallyloxyethane. One or two or more of these monomers can be used in combination.

In the present invention, the amount of each of the components (a) to (e) must be determined in due consideration of the performance of the obtained copolymer as a papermaking additive. Is preferable. The amount of the component (d) necessary for giving the acrylamide polymer a branched structure depends on the amount of the monomer (a), (b),
Usually 0.00 based on the total molar amount of the components (c) and (e).
It is in the range of 5 to 5 mol%, preferably 0.01 to 2 mol%. When the amount is less than 0.005 mol%, the branched structure of the acrylamide polymer is insufficient, and the paper strength enhancing effect is obtained.
Undesirably low drainage effect. Further, when it exceeds 5 mol%, the obtained polymer becomes less water-soluble and becomes water-insoluble, or the viscosity of the polymer excessively increases,
It is not preferable because it may gel.

The amount of the component (a) used is usually 98 to 60 mol%, preferably 96 to 70 mol%, based on the total molar amount of the monomers (a), (b), (c) and (e) used. %. Similarly, the component (b) is usually 1 to 20 mol%, preferably 2 to 15 mol%, and the component (c) is also usually 1 to 20 mol%, preferably 2 to 15 mol%.
It is. Similarly, component (e) is usually at most 25 mol%, preferably at most 20 mol%. Outside this range, a sufficient paper strength enhancing effect and drainage effect cannot be obtained in any case.

The synthesis of the acrylamide polymer used in the present invention can be carried out by various conventionally known methods. For example, in a given reaction vessel, the monomer concentration is 2-3.
The components (a), (b), (c), (d) and (e) and water are charged so as to be 0 mol%, preferably 5 to 30 mol%, and a radical polymerization initiator is added. The desired acrylamide-based polymer can be obtained by appropriately using a chain transfer agent such as isopropyl alcohol, allyl alcohol and the like and heating with stirring.

Examples of the radical polymerization initiator include persulfates such as sodium persulfate, potassium persulfate and ammonium persulfate; peroxides such as hydrogen peroxide and benzoyl peroxide; bromates such as sodium bromate and potassium bromate. Perborate salts such as sodium perborate, potassium perborate and ammonium perborate; percarbonates such as sodium percarbonate, potassium percarbonate and ammonium percarbonate; sodium perphosphate, potassium perphosphate; Examples include superphosphates such as ammonium phosphate, tert-butyl peroxide, and the like. In this case, although it can be used alone, it can also be used as a redox polymerization initiator in combination with a reducing agent.

Examples of the reducing agent include sulfites, bisulfites, organic amines such as N, N, N ', N'-tetramethylethylenediamine, and azo compounds such as 2,2'-azobis-2-amidinopropane hydrochloride. And reducing sugars such as aldose. Azobisisobutyronitrile, 2,2'-azobis-2-amidinopropane hydrochloride, 2,2'-azobis-2,4-dimethylvaleronitrile, 4,4'-azobis-4-cyanovaleic acid and Azo compounds such as salts thereof can also be used. Two or more of these initiators can be used in combination. The viscosity of the obtained acrylamide-based polymer is usually preferably 15,000 cps or less from the viewpoint of workability.

In using the papermaking additive of the present invention, a conventionally known method may be used. That is, papermaking is performed by adding the papermaking additive of the present invention to an aqueous dispersion of pulp, and papermaking can be performed in a system in which a sulfate band is present or in a system in which it is not present. Effect and drainage effect. When making paper, a usual internal sizing agent or a filler such as clay, talc, and titanium oxide can be added.

[0038]

Next, the present invention will be described in more detail with reference to examples and comparative examples. All parts and percentages are based on weight.

Example 1 In a 1-liter four-necked flask equipped with a stirrer, a thermometer, a reflux condenser, and a nitrogen gas inlet tube, 191.91 g (90 mol%) of a 50% aqueous acrylamide solution, 98% acrylic acid 5. 52 g (5 mol%), dimethylaminoethyl methacrylate 11.79 g (5 mol%), methacrylonitrile alkoxy <br/> trimethoxysilane 1.05 g (0.3 mol%), water 349.28G, 15% sulfuric acid 23 .57 g, and then 4.45 g of a 5% aqueous solution of ammonium persulfate.
Was added, and the temperature was raised to 80 ° C. under the introduction of nitrogen gas and reacted for 2 hours. The solid content was 21.5%, the viscosity (25 ° C.) was 6650 cps,
An aqueous solution of an acrylamide polymer having a pH of 3.8 was obtained. This is designated as Papermaking Additive A. Table 1 shows the property values of the obtained acrylamide-based polymer.

Examples 2 to 8 and Comparative Example The procedure of Example 1 was repeated except that the types and amounts of the components (a) to (e) were changed and the types and amounts of the polymerization initiator were changed as shown in Table 1. The same operation as in Example 1 was performed to obtain an aqueous solution of an acrylamide polymer. Table 1 shows the property values of the aqueous solutions of the polyacrylamide copolymers obtained in the examples and comparative examples.

In the table, AAm: acrylamide, DMAA
m: dimethylacrylamide, MAAm: methacrylamide, AA: acrylic acid, IA: itaconic acid, MA: maleic acid, MAA: methacrylic acid, FA: fumaric acid, D
M: dimethylaminoethyl methacrylate, DMC: methacryloxyethyltrimethylammonium chloride, DPA: dimethylaminopropylacrylamide,
DMBz: methacryloxyethyldimethylbenzylammonium chloride, BQA: 2-hydroxy N, N,
N, N ', N'-pentamethyl-N'-[3-{(1-
Oxo-2-propenyl) amino {propyl] -1,3
-Propanediaminium dichloride, MPTMSi:
Methacrylonitrile trimethoxysilane,

[0042]

Embedded image MPMDMSi: methacrylo propyl methyl dimethoxy silane, VTESi: vinyltriethoxysilane,
VTacOSi: vinyltriacetoxysilane, DVD
ESi: divinyldiethoxysilane, VTCSi: vinyltrichlorosilane, MBAAm: methylenebisacrylamide, AN: acrylonitrile, BA: butyl acrylate, MMA: methyl methacrylate. (D)
The amounts of the components used indicate mol% based on the total molar amount of the components (a), (b), (c) and (e).

(Performance evaluation method) 307 ml of beating degree (Canadian Standard Freeness, hereinafter abbreviated as CSF) obtained from waste corrugated paper containing coated paper broke.
Was added to a pulp slurry having a concentration of 2.4% and a sulfuric acid band was added to the pulp at a pH of 7.0 by adding 0.5% to the pulp slurry, and C.I.
S. To a pulp slurry having a concentration of 2.4% adjusted to 350 ml of F, 1.5% of a sulfuric acid band was added to the pulp, and p
A pulp slurry having H of 5.0 was prepared.

Next, the aqueous solution of the acrylamide-based polymer obtained in the above Examples and Comparative Examples, that is, the papermaking additive was added to each pulp slurry by 0.6% based on the pulp.
After adding and stirring, the pulp slurry concentration is 0.25%
Diluted with a Noble & Wood sheet machine, and dried at 110 ° C with a drum dryer.
After drying for 90 seconds, two types of handmade paper having a basis weight of 80 and 170 g / m ² were obtained. The obtained stock is 20 ° C, 65%
R. H. After conditioning for 24 hours under the above conditions, the samples were subjected to each measurement. In addition, the addition rate of the above-mentioned chemicals is a solid content weight ratio to the pulp absolute weight.

Tables 2 and 3 show the measurement results. Table 2, Table 3
Were performed according to the following method. Specific burst strength: JIS P 8112 Specific compressive strength: JIS P 8126 DDT: “D” described on page 46 of Tappi Journal Vol. 56, No. 10, (1973)
dynamic drain Jar ", 500 ml of the pulp slurry was about 7.5 cm in diameter.
The lower cock was opened while stirring at 800 rpm, and the mixture was filtered through a 100-mesh wire gauze. The time required for the filtrate amount to be constant was measured and used for evaluation of drainage. Here, the filtrate volume is 250
The time to reach ml was measured.

[0046]

[Table 1]

[0047]

[Table 2]

[0048]

[Table 3]

[0049]

The papermaking additives according to the present invention are shown in Tables 2 and 3
As shown in the above, excellent paper strength and drainage can be provided as compared with conventionally known polyacrylamide-based polymers having a relatively low molecular weight.

Continuation of the front page (56) References JP-A-59-187697 (JP, A) JP-A-5-86597 (JP, A) JP-A-60-155573 (JP, A) JP-A-4-18190 (JP) JP-A-2-139495 (JP, A) JP-A-60-155762 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) D21H 11/00-27/42

Claims (2)

(57) [Claims] 1. Acrylamides (a), vinyl monomers (b) having an anionic group copolymerizable with the component (a), vinyl monomers (c) having a cationic group copolymerizable with the component (a), Copolymerizable with the silicon compound (d) containing at least one unit represented by the formula (1) and at least one unit represented by the general formula (2) and optionally the component (a) A paper-making additive comprising a copolymer obtained by polymerizing a nonionic vinyl monomer (e). Embedded image [However, in the formula (1), R ¹ represents a hydrogen atom or a methyl group]. Embedded image [Z is the same or different from the following formulas (3.1) to (3 ·
7) represents a group represented by any of the above. However, (3
The groups represented by 5) to (3.7) represent S represented by the formula (2)
Except when all three of Z bonded to i are occupied). Embedded image [In the formulas (3.1) to (3.7), X represents a halogen atom, and R ² and R ³ each independently represent a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, oxygen, nitrogen or halogen. An alkyl group having 1 to 4 carbon atoms having a substituent, a phenyl group or a phenyl group having a substituent containing oxygen, nitrogen or halogen, R ⁴ is a hydrogen atom,
4 alkyl group, oxygen, nitrogen or an alkyl group having 1 to 4 carbon atoms which has a substituent containing a halogen, a phenyl group, an oxygen, a phenyl group or a benzyl group having a substituent containing a nitrogen or halogen, R ⁵ is Represents a hydrogen atom or a methyl group]. 2. The copolymer according to claim 1, wherein the amount of the silicon compound (d) is 0.005 to 5 mol% based on the total molar amount of the components (a), (b), (c) and (e). 2. The papermaking additive according to claim 1, wherein the additive is present in the range and polymerized.