JP2676523B2 - Sizing composition for papermaking and method for sizing paper - Google Patents

Description

TECHNICAL FIELD The present invention relates to a sizing composition for papermaking and a method for sizing paper, and more particularly to a ketene dimer sizing composition for papermaking with improved storage stability and sizing effect. The present invention relates to an article and a method for sizing paper or paperboard using the same.

2. Description of the Related Art Conventionally, sizing has been performed in ordinary paper and paperboard papermaking methods in order to provide these papers with functions such as size, waterproofness, and water resistance. As one of the sizing methods, acidic sizing has been performed in which a rosin sizing agent having a carboxyl group and a sulfuric acid band are used to perform sizing in an acidic range of pH 4.5 to 6.5. On the other hand, in recent years, neutral sizing agents have been used for the purpose of using inexpensive calcium carbonate as a filler, using broke or waste paper containing calcium carbonate, closing water for papermaking, and imparting permanent preservation of paper. A so-called neutral sizing method in which sizing is performed in a neutral to weakly alkaline range of pH 6.5 to 9 has been attracting attention.

Known neutral sizing agents currently on the market include ketene dimer compounds, substituted cyclic dicarboxylic acid anhydrides, copolymers of cationic monomers and hydrophobic monomers, cationized petroleum resins, cationized fatty acid amides, etc. However, among these, ketene dimer compounds are often used from the viewpoint of size effect.

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention However, the ketene dimer compound exhibits a size effect under a normal drying condition in a papermaking process after a certain amount of time has elapsed after the drying, but exhibits a sufficient size effect immediately after the drying. Not done.

Therefore, in order to improve the surface characteristics of the paper during the paper manufacturing process, for example, various characteristics such as pen writing property, anti-slip property, and smoothness,
When the aqueous working liquid is applied to the paper with a calender, size press, coater or the like, the amount of the aqueous working liquid absorbed by the paper increases. In order to control the liquid absorption amount so as not to increase, it is unavoidable to use an excess amount of the ketene dimer compound more than the amount required to exert a sufficient size effect after drying. Excessive use of this ketene dimer compound is not only economically disadvantageous, but it also causes operating troubles such as the generation of lees containing the ketene dimer compound on the press rolls and soiling of paper and papermaking equipment. Cause to cause.

Further, the ketene dimer compound has hitherto been commercially available and used as an aqueous dispersion prepared by dispersing it in an aqueous continuous phase containing starch, particularly cationized starch. However, ketene dimer-based compounds inherently easily react with water, and it is difficult to obtain a stable aqueous dispersion. For example, during storage, the dispersion loses uniformity and gels or precipitates.
Further, there is a problem that effects such as size and waterproofness are reduced. In particular, it is more difficult to obtain a stable aqueous dispersion having a high concentration.

In order to stabilize the aqueous dispersion of the ketene dimer compound, JP-A-60-258244 discloses a method of dispersing the ketene dimer compound in an aqueous continuous phase containing an acrylamide polymer having a cationic group. However, the sizing agent using this method also has a problem that the sizing effect immediately after the paper or the paperboard is dried is insufficient.

An object of the present invention is to improve the storage stability and the sizing effect immediately after the paper or paperboard is dried in the ketene dimer-based sizing composition for papermaking. Another object of the present invention is to provide a sizing method which does not stain the papermaking apparatus by using the sizing composition for papermaking.

Means for Solving the Problems The present inventors have conducted intensive studies in order to solve the above-mentioned problems. As a result, (a) a ketene dimer compound represented by the following general formula (I): (In the formula, R ₁ and R ₂ represent the same or different hydrocarbon groups having 8 to 30 carbon atoms.) (B) A monomer containing 5 mol% or more of the monomer represented by the following general formula (II) (carbon number: Polymer except a long chain alkyl group-containing monomer having a 4-28 alkyl group and a polymerizable functional group) (In the formula, n is 2, 3 or 4, R ₃ represents a hydrogen atom or a methyl group, R _{4 to} R ₈ are the same or different lower alkyl groups having 1 to 3 carbon atoms, X ⁻ and Y ⁻ are the same or Which represents different anions), and from 2.5 to 100 parts by weight of the polymer of (b) per 100 parts by weight of the compound of (a), or contains 50 parts by weight or less of cationized starch, Is 15 parts by weight or less of an anionic dispersant containing one or more selected from the group consisting of a sulfonic acid group, a sulfuric ester group and salts thereof. A composition is provided. In this case, the polymer (b) is composed of a polymer of 5 mol% or more of the monomer of the general formula (II) and 95 mol% or less of acrylamide and / or methacrylamide, and the polymer of the general formula (II) It may be a homopolymer of monomers, and the viscosity of a 20% by weight aqueous solution of each of these polymers is 10 to 5000.
It is preferably centipoise (however, measured by Brookfield viscometer at 25 rpm at 60 rpm).

Further, the present invention provides a method for sizing paper, which comprises sizing paper or paperboard using the sizing composition for papermaking.

 Next, the present invention will be described in detail.

As the ketene dimer compound used in the present invention,
It is a compound represented by the above general formula (I), and any of various known ketene dimer compounds can be used.

In the general formula (I), R ₁ and R ₂ represent the same or different hydrocarbon groups having 8 to 30 carbon atoms, and examples of the hydrocarbon group include decyl, dodecyl, tetradecyl, hexadecyl, octadecyl and eicosyl. And alkyl groups such as tetradecenyl, hexadecenyl, octadecenyl, etc., alkyl substituted phenyl groups such as octylphenyl, nonylphenyl, etc., alkyl substituted cycloalkyl groups such as nonylcyclohexyl, aralkyl groups such as phenylethyl, etc. Of these, alkyl groups are preferred. These ketene dimer compounds may be used alone or in combination.
Used as a mixture of more than one species.

Further, the polymer (b) of the present invention is obtained by polymerizing a monomer containing 5 mol% or more of the monomer represented by the general formula (II). It may also be a mol%, ie a homopolymer, which the present invention also includes.

As a monomer copolymerizable with the monomer represented by the general formula (II), for example, a cationic monomer,
(Mono- or di-alkyl) aminoalkyl (meth)
Acrylamide (eg, dimethylaminopropyl methacrylamide, dimethylaminopropyl acrylamide, etc.), (mono- or di-alkyl) aminoalkyl (meth) acrylate (eg, dimethylaminoethyl methacrylate, dimethylaminoethyl acrylate, etc.), (mono-, or Di-alkyl) amino hydroxyalkyl (meth) acrylate, vinyl pyridine, vinyl imidazole, diallyl amine and the like can be used, and further, quaternary ammonium salts thereof can be used. Also,
As a nonionic monomer, (meth) acrylamide,
N, N-dimethylacrylamide, hydroxyethyl (meth) acrylate, etc. can be used. Furthermore, as the anionic monomer, (meth) acrylic acid, maleic acid,
Monomers having carboxylic acid groups such as fumaric acid, itaconic acid, citraconic acid, crotonic acid, vinyl sulfonic acid,
(Meth) allyl sulfonic acid, 2-acrylamido-2-
A monomer having a sulfonic acid group such as methyl propane sulfonic acid or sulfonated styrene, a monomer having a phosphoric acid ester group such as a phosphoric acid ester of hydroxyalkyl (meth) acrylate, and salts thereof can be used. As the styrene, vinyl ester such as styrene or its derivative, alkyl (meth) acrylate, (meth) acrylonitrile, vinyl acetate or vinyl propionate, or methyl vinyl ether can be used. In the above-mentioned "alkyl" -containing monomer, the "alkyl" excludes long-chain alkyl groups having an alkyl group having 4 to 28 carbon atoms and a polymerizable functional group. Although these monomers can be appropriately combined and used, (meth) acrylamide is particularly preferable among them.

The polymer (b) used in the present invention is obtained by polymerizing a monomer containing 5 mol% or more of the monomer represented by the general formula (II), preferably 20 mol%.
That is all. If this content is less than 5 mol%, the size effect immediately after the paper or paperboard is dried is insufficient even if this polymer is used together with the respective components such as (a) in the range of the use ratio of the present invention. .

A conventionally known method can be applied to synthesize the polymer (b). That is, the monomer represented by the general formula (II), or the monomer represented by the general formula (II) and other monomers are water; alcohols such as methanol, ethanol, isopropyl alcohol; dimethyl sulfoxide, dimethylformamide; It can be obtained by carrying out a polymerization reaction in the presence of a radical polymerization catalyst in a solvent such as a mixed solution. Examples of the radical polymerization catalyst include persulfates such as ammonium persulfate, potassium persulfate and sodium persulfate, redox polymerization catalysts obtained by combining these persulfates and a reducing agent, or 2,2′-azobis-
Examples thereof include azo catalysts such as (2-amidinopropane) dihydrochloride and 2,2'-azobisisobutyronitrile. Further, a known chain transfer agent can be appropriately used if necessary.

The viscosity of the polymer solution (b) thus obtained can be that of a 20% by weight aqueous solution of 10 to 5000 centipoise (however, Brookfield viscometer is measured at 25 rpm at 60 rpm). , Especially the above viscosity is 50 ~ 10
00 centipoise is preferable. When this viscosity is lower than 10 centiboise or higher than 5000 centiboise, when it is used as the component (b) of the present invention, emulsifying property and storage stability are higher than those using those having the above viscosity range. Tends to be inferior.

The polymer (b) is used in an amount of 2.5 to 100 parts by weight, preferably 5 to 50 parts by weight, based on 100 parts by weight of the ketene dimer compound represented by the general formula (I). 2.5
When the amount is less than 100 parts by weight, the emulsifiability is poor, and it is not possible to obtain a stable sizing composition for papermaking. When the amount is 100 parts by weight or more, not only is it economically disadvantageous but also adversely affects the size effect. .

In the present invention, as described above, the compound (a),
By using the polymer of (b) together, excellent storage stability of the sizing composition for papermaking and excellent sizing effect immediately after papermaking and drying can be obtained, but if necessary, cationized starch and / or sulfonic acid group It is also preferable to use an anionic dispersant containing one or more selected from the group consisting of sulfate ester groups and salts thereof, in view of further improving the storage stability of the sizing agent.

As the cationized starch, corn, potato or tapioca starch containing a primary, secondary, tertiary amino group or quaternary ammonium salt can be used, and the ketene dimer represented by the general formula (I) can be used. It is preferable to use 50 parts by weight or less, preferably 3 to 30 parts by weight, relative to 100 parts by weight of the compound.

As the anionic dispersant, for example, glycine sulfonate, naphthalene sulfonate-formaldehyde condensate or the like can be used, and ketene dimer compound 10
It is used in an amount of 15 parts by weight or less, preferably 0.1 to 5 parts by weight, based on 0 parts by weight.

In the present invention, substances conventionally used for ketene dimer type sizing agents such as nonionic dispersants such as sorbitan ester can also be used in combination.

The sizing composition for papermaking of the present invention can be produced by a conventionally known method. For example, the ketene dimer compound and the polymer of the above (b) and optionally a cationized starch and / or an anionic dispersant are aqueous at a temperature not lower than the melting point of the ketene dimer compound represented by the general formula (I). It can be obtained by mixing in a solvent and uniformly dispersing with a known mixer such as a homomixer, a high-pressure discharge homogenizer, an ultrasonic emulsifier or the like. As the order of mixing, for example, a ketene dimer compound, the polymer of the above (b) and, if necessary, an anionic dispersant are mixed in an aqueous medium and uniformly dispersed, and then a cationized starch is mixed, Alternatively, the ketene dimer compound and the cationized starch may be mixed with an anionic dispersant, if necessary, in an aqueous medium and uniformly dispersed, and then the polymer (b) may be mixed.

The papermaking sizing composition of the present invention thus obtained has a dispersed phase particle system of 10 μm or less and 15 to 30% by weight.
The storage stability is extremely excellent at the solid content concentration of, and an excellent sizing effect can be exhibited immediately after paper or paperboard is made and dried.

The papermaking sizing composition of the present invention can be used by a conventionally known method of use. For example, in the manufacturing process of paper or paperboard, either the so-called internal sizing method of adding to the wet end part or the so-called surface sizing method of applying or impregnating after forming the paper layer can be used.

When used in the internal addition sizing method, the papermaking sizing composition of the present invention is added to an aqueous dispersion of pulp in an amount of 0.002 to 3% by solid weight based on the dry weight of the pulp, preferably 0.005.
Add ~ 2 solids wt%.

Pulp raw materials include bleached or unbleached chemical pulp such as kraft pulp or sulfite pulp, groundwood pulp,
Either bleached or unbleached high-yield pulp such as mechanical pulp or thermomechanical pulp, or waste paper pulp such as waste newspaper, magazine waste paper, corrugated waste paper, or deinked waste paper can be used.

Fillers, dyes, dry strength agents, wet strength agents, additives such as retention agents may also be used as needed,
If necessary, starch, polyvinyl alcohol, dye, coating color, surface sizing agent, anti-slip agent, etc. may be applied with a size press, gate roll coater, bill blade coater, calender, or the like.

The internal addition sizing method using the papermaking sizing composition of the present invention exhibits an excellent sizing effect immediately after the paper or paperboard is dried, and can reduce stains on the papermaking machine and enhance operability. .

Further, when using the papermaking sizing composition of the present invention in the surface sizing method, the papermaking sizing agent of the present invention in the surface coating liquid to be applied with a size press, a gate roll coater, a bill blade coater, a calender, etc. The composition may be added so as to be applied on the surface of paper at 0.005 to 0.5 g / m ² (dry weight).

Examples Hereinafter, examples of the present invention will be described, but the present invention is not limited to these. In the following Examples and Comparative Examples,% and parts mean% by weight and parts by weight, respectively, unless otherwise specified.

Example 1 a stirrer, a thermometer, a reflux condenser and the four-necked flask 1 equipped with a nitrogen gas introducing tube general formula (II) in _{n = 3, R 3 = H} , R 4 ~R 8 = CH ₃ , 330 g of a 60% aqueous solution of a monomer of X ⁻ = Y ⁻ = Cl ⁻ , 4 g of isopropyl alcohol and 165 g of ion-exchanged water were charged, and the pH was adjusted to 3.8 with a 20% aqueous sulfuric acid solution. Nitrogen gas was introduced while stirring this mixed solution to remove oxygen, and then the temperature was raised to 65 ° C., and 1.4 g of a 5% aqueous solution of ammonium persulfate was added to initiate polymerization. afterwards
The temperature was raised to 80 ° C. and maintained at 80 ° C. for 1.5 hours, 0.7 g of a 5% aqueous solution of ammonium persulfate was added, and the temperature was maintained at the same temperature for 1.5 hours to complete the polymerization. Ion-exchanged water (490 g) was added to the obtained polymerization product to give a nonvolatile content of 20.5% per minute.
A polymer aqueous solution P-1 having a Brookfield viscosity (hereinafter referred to as viscosity) 930 centipoise (hereinafter referred to as cps) and a pH of 4.2 measured at 60 rotations was obtained.

Then, 18.18 parts of a ketene dimer compound (using a mixture of 40% palmitic acid chloride and 60% stearic acid chloride as a raw material), 8.87 parts of a polymer aqueous solution P-1 obtained by the above-mentioned polymerization and 72.95 of ion-exchanged water.
Part to 70 ° C and predisperse with a homomixer, then use a high pressure discharge homogenizer while maintaining the same temperature.
It was dispersed twice by passing it twice under a shearing pressure of 250 kg / cm ² . After cooling, the mixture was filtered through a wire mesh of 325 mesh to obtain a papermaking sizing composition E-1 as an aqueous dispersion. This papermaking sizing composition E-1 has a nonvolatile content of 20.2%, a viscosity of 43.0 cps, and a pH.
Was 3.5. In order to investigate the storage stability of the papermaking sizing agent E-1, it was stored at 32 ° C. for one month and the change in viscosity with time was examined. Table 2 shows the results.

Examples 2 to 5 Polymerization was performed in the same manner as in Example 1 except that the monomer composition was changed to that shown in Table 1, and polymer aqueous solutions P-2 to P- were used.
5 was obtained. The amount of isopropyl alcohol for adjusting the viscosity was appropriately changed each time. Then, a papermaking sizing composition was prepared in the same manner as in Example 1 except that the compounding ratio of ketene dimer compound / (b) polymer / cationized starch / anionic dispersant was changed as shown in Table 2. E-2
~ E-5 were obtained, the storage stability of each of them was examined in the same manner as in Example 1, and the results are shown in Table 2. Table 1
The symbols indicate the following.

M-1; In the general formula (II), n = 3, R ₃ = H, R _{4
= CH 3, R 5 = CH} 3, R 6 = CH 3, R 7 = CH 3, R 8 = CH 3, X - = C
Monomers of l ⁻ and Y ⁻ = Cl ⁻ M-2; Quaternary product of dimethylaminopropylacrylamide with methyl chloride M-3; Quaternary product of dimethylaminoethyl methacrylate with methyl chloride M-4; Acrylamide Comparative Examples 1 to 1 3 Polymer aqueous solution shown in Table 1 in the same manner as in Examples 2-5
RP-1 to RP-3 were obtained, and using them, paper making size compositions RE-1 to RE-3 were similarly obtained, and the storage stability thereof was similarly examined. The results are shown in Table 2.

Example 6 17.32 parts of the ketene dimer compound used in Example 1
82.46 parts of a 3.15% aqueous solution of cationized starch (cationized potato starch containing 0.4% of nitrogen atoms in a quaternary ammonium salt) pregelatinized at 90 ° C. for 1 hour and 40% aqueous solution of sodium naphthalenesulfonate-formaldehyde condensate
After heating 0.22 parts to 70 ° C and predispersing with a homomixer, keep it at the same temperature and use a high pressure discharge type homogenizer.
It was dispersed twice by passing it twice under a shearing pressure of 250 kg / cm ² . After cooling 88.5 parts of this aqueous dispersion, it was mixed with 11.5 parts of the polymer aqueous solution P-6 shown in Table 1 and filtered through a 325 mesh wire mesh to prepare an aqueous dispersion of the papermaking sizing composition E.
-6 was obtained. Table 2 shows the results of the same measurement as described above.

Comparative Examples 4 to 6 Table 2 shows the results of examining the physical properties and storage stability of the papermaking sizing compositions RE-4 to RE-6 containing 3 types of commercially available ketene dimer compounds as comparative examples. .

In Table 2, the ketene dimer compound is made from a mixture of 40% palmitic acid chloride and 60% stearic acid chloride as a raw material, the aqueous polymer solution is as shown in Table 1, and the cationized starch is a quaternary ammonium salt with a nitrogen atom of 0. .
Cationized potato starch containing 4%, 90% at the specified concentration
The mixture was gelatinized at 1 ° C for 1 hour, the anionic dispersant was sodium naphthalenesulfonate-formaldehyde condensate, but sodium ligninsulfonate was used for Example 2, and the storage stability was stored at 32 ° C for 1 month. It is the latter viscosity.

Next, the size effect test was conducted using the papermaking sizing composition obtained above.

That is, a pulp slurry having a concentration of 2.4% [BKPL / N = 8 /
2, Canadian Standard Freeness 380 ml] with heavy calcium carbonate (Escalon 1500, Sankyo Milling Co., Ltd.)
20% was added, and after stirring for 2 minutes, 0.75% of cationized starch (Kate F, manufactured by Oji National Co., Ltd.) and 0.5% of bansulfate were sequentially added, and the mixture was further stirred for 2 minutes. Then, after the pulp slurry concentration was diluted to 0.24%, the papermaking sizing compositions E-1 to E- obtained in Examples 1 to 6 and Comparative Examples 1 to 6 were obtained.
6 and RE-1 to RE-6, each 0.12%, retention improver (High Reten 104, manufactured by Dick Hercules) 0.02
% Was added and stirred for 1 minute. Using the thus obtained paper material, a wet paper having a basis weight of 70 g / m ² was obtained with a hand-making machine manufactured by Noble and Wood Co. The papermaking pH was 8.0. The wet paper was pressed until the moisture content became 59.0%, and then dried at 80 ° C. for 70 seconds with a drum dryer. Immediately after drying, paper having a water content of 4.0% was obtained. This dried paper and 20
The Steckigt sizing degree of the paper after 7 days in an atmosphere of ° C and relative humidity of 65% was measured according to JIS P-8122. Table 3 shows the results.

In addition, the addition rate of the filler and the chemical is a solid content weight% with respect to the dry pulp weight.

Examples 7 to 12 and Comparative Examples 7 to 10 Further, a test was conducted to see the state in which the lees of the papermaking sizing composition stain the equipment when papermaking is continuously performed.

That is, among the stocks used for the size effect test, the same stocks as the corresponding stocks used in Examples 1 to 6 and Comparative Examples 1, 4, 5 and 6 were prepared. Was made with a pilot machine. Each stock was run for 15 minutes and the next stock was switched continuously. It took 10 minutes for the papermaking system to stabilize after switching, so the residue accumulated in the doctor of the No. 2 press was collected and dried after 10 minutes from switching and before switching to the next stock. And weighed. Table 4 shows the results.

The papermaking conditions are as follows.

Papermaking machine: Fourdrinier / multi-cylinder pilot machine Papermaking speed: 25m / min Papermaking pH: 7.9 Papermaking temperature: 18 ° C Basis weight: 65g / m ² or more, Papermaking size of Examples 1-6 and Comparative Examples 1-6 Comparing the sizing compositions based on Tables 2 and 3, the examples have good storage stability, and the sizing effects using these sizing compositions for papermaking are also compared, and It can be seen that the size effect immediately after drying is good and the size effect after aging is also excellent. Moreover, when comparing the state of soiling the lees of the papermaking sizing composition according to the papermaking methods of Examples 7 to 12 and Comparative Examples 7 to 10, the methods of Examples are significantly less, It can be seen that this is due to the use of the papermaking sizing compositions 1 to 7.

EFFECTS OF THE INVENTION According to the present invention, the ketene dimer compound is used in combination with the polymer (b), and if necessary, a cationized starch and / or an anionic dispersant is used in combination.
The storage stability of the papermaking sizing composition containing these as the main components is improved, and the sizing effect of paper using the papermaking sizing composition immediately after papermaking and drying can be improved, and the papermaking By making a paper using the sizing composition for use in paper, it is possible to reduce the contamination of the device due to the residue of the sizing composition for papermaking, and to improve the operability.

 ─────────────────────────────────────────────────── ─── Continued Front Page (72) Inventor Mayumi Narushima, 17 Ichihara, Ichihara, Chiba Prefecture 2 Dick Hercules Co., Ltd. Research Laboratory (56) References JP-A-111094 (JP, A) Kai 59-22911 (JP, A) JP 60-104599 (JP, A)

Claims (6)

(57) [Claims] (1) a ketene dimer compound represented by the following general formula (I): (In the formula, R ₁ and R ₂ represent the same or different hydrocarbon groups having 8 to 30 carbon atoms.) (B) A monomer containing 5 mol% or more of the monomer represented by the following general formula (II) (carbon number: Polymer except a long chain alkyl group-containing monomer having a 4-28 alkyl group and a polymerizable functional group) (In the formula, n is 2, 3 or 4, R ₃ represents a hydrogen atom or a methyl group, R _{4 to} R ₈ are the same or different lower alkyl groups having 1 to 3 carbon atoms, X ⁻ and Y ⁻ are the same or Which represent different anions), and 2.5 to 100 parts by weight of the polymer of (b) with respect to 100 parts by weight of the compound of (a). 2. The papermaking sizing composition according to claim 1, containing 50 parts by weight or less of cationized starch with respect to 100 parts by weight of the compound (a). 3. Anionic dispersant containing one or more selected from the group consisting of sulfonic acid groups, sulfuric acid ester groups and salts thereof per 100 parts by weight of the compound (a). The sizing composition for papermaking according to claim 1 or 2, characterized in that it is contained in an amount of not more than 1 part by weight. 4. The polymer of (b) is represented by the general formula (II).
The monomer is composed of a polymer of 5 mol% or more of a monomer and 95 mol% or less of acrylamide and / or methacrylamide. The viscosity of a 20 wt% aqueous solution of this polymer is 10 to 5000 centipoise (however, Brookfield viscosity The measured value at 60 ° C. per minute at 25 ° C.). The paper sizing composition according to claim 1, 2, or 3. 5. The polymer (b) is represented by the general formula (II).
Is a homopolymer of 20% by weight of this polymer.
The viscosity of the aqueous solution is 10 to 5000 centipoise (however, measured at 25 ° C. at 60 rpm with a Brookfield viscometer). Claims 1, 2 or 3
A sizing composition for papermaking according to the item. 6. A method for sizing paper, which comprises sizing paper or paperboard using the sizing composition for papermaking according to any one of claims 1 to 5.