JP2838209B2 - Internal sizing composition for papermaking and internal sizing method - Google Patents

Description

Description: FIELD OF THE INVENTION The present invention relates to an internal sizing composition for papermaking and an internal sigging method, and more particularly, to a high concentration and excellent storage stability, mechanical stability and sizing effect. The present invention relates to an internal sizing composition for ketene dimer paper and an internal sizing method 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 the sizing method, a so-called internal sizing method in which an internal sizing agent is added to the stock before the paper layer is formed in the paper or paperboard manufacturing process, and a surface sizing agent is applied to the paper surface after the paper layer is formed Alternatively, there is a so-called surface sizing method for impregnation.

As an internal sizing method, acidic sizing has been performed in which an internal sizing is performed in an acidic range of pH 4.5 to 6.5 using a rosin sizing agent having a carboxyl group and a sulfate band. On the other hand, in recent years, a neutral sizing agent has been used for the purpose of using inexpensive calcium carbonate as a filler, using waste paper or waste paper containing calcium carbonate, closing papermaking water, and imparting permanent storage properties of paper. A so-called neutral sizing method in which internal sizing is performed in a neutral to weakly alkaline region at pH 6.5 to 9, has been attracting attention.

Known commercially available neutral sizing agents include ketene dimer compounds, substituted cyclic dicarboxylic anhydrides, copolymers of cationic and hydrophobic monomers, cationized petroleum resins, and cationized fatty acid amides. However, among these, an aqueous dispersion of a ketene dimer compound is often used in view of the size effect.

Problems to be Solved by the Invention Conventionally, ketene dimer compounds are commercially available and used as an aqueous dispersion dispersed 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. Particularly, it is very difficult to obtain an aqueous dispersion having a high concentration and excellent storage stability and mechanical stability.

In order to stabilize the aqueous dispersion of the ketene dimer compound, JP-A-60-258244 discloses a method of dispersing a ketene dimer compound in an aqueous continuous phase containing an acrylamide polymer having a cationic group. However, the internal sizing composition for paper making using this method is still insufficient in mechanical stability, storage stability and size effect.

SUMMARY OF THE INVENTION An object of the present invention is to provide an internal sizing composition for papermaking, which has a high concentration in a ketene dimer-based internal sizing composition for papermaking and can enhance storage stability, mechanical stability and sizing effect. To provide a sizing method for internal addition.

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 vinyl monomer is polymerized or copolymerized in the presence of an alkyl mercaptan having 6 to 22 carbon atoms. An internal sizing composition for papermaking, comprising 2 to 100 parts by weight of the hydrophilic polymer (b) with respect to 100 parts by weight of the compound (a). The purpose of the present invention is to provide an internal sizing method. In this case, the alkyl mercaptan having 6 to 22 carbon atoms in the above (b) is preferably present in an amount of 0.01 to 10 mol% based on the vinyl monomer, and a hydrophilic polymer composed of the vinyl monomer is an acrylamide polymer; Alternatively, a copolymer of acrylamide and a cationic vinyl monomer, a copolymer of acrylamide and an anionic vinyl monomer, or a copolymer of acrylamide, a cationic vinyl monomer, and an anionic vinyl monomer is preferable.

 Next, the present invention will be described in detail.

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

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

Further, the hydrophilic polymer (b) of the present invention has 6 carbon atoms.
Obtained by polymerizing or copolymerizing a vinyl monomer in the presence of an alkyl mercaptan having a carbon number of
The alkyl groups of Nos. To 22 may be either linear or branched, and the raw materials for the alkyl group may be natural or those artificially produced such as cracking of low-polymerized paraffin such as ethylene or propylene. For example, normal octyl mercaptan, normal dodecyl mercaptan, tertiary decyl mercaptan, normal hexadecyl mercaptan, normal octadecyl mercaptan and the like can be mentioned, and these can be used alone or as a mixture of two or more. Of these, normal octyl mercaptan and normal dodecyl mercaptan are preferred.

In (b) of the present invention, the alkyl mercaptan having 6 to 22 carbon atoms is preferably 0.01 to 10 mol%, most preferably 0.1 to 10 mol%, based on the vinyl monomer used for polymerization or copolymerization.
It is used in an amount of 05 to 2 mol%. Alkyl mercaptan is 0.01
If the amount is less than 10 mol%, a stable internal sizing composition for papermaking may not be obtained.
When used in excess of, the amount of alkyl mercaptan not introduced into the polymer during the polymerization or copolymerization reaction increases,
The equipment used for the polymerization reaction may become fouled, adversely affect storage stability and sizing effect, and further increase the cost of the internal sizing composition for papermaking.

Examples of the vinyl monomer as a raw material of the hydrophilic polymer (b) of the present invention include, as a cationic vinyl monomer, (mono- or di-alkyl) amino (hydroxy) alkyl (meth) acrylate, (mono- or Di-alkyl) aminoalkyl (meth) acrylamide,
Vinyl pyridine, vinyl imidazole, diallylamine and the like can be used, and furthermore, salts of these inorganic or organic acids or quaternary ammonium salts can be used. As the nonionic vinyl monomer, (meth) acrylamide, N, N'-dimethylacrylamide, hydroxypropyl (meth) acrylate, or the like can be used. Further, as anionic vinyl monomers, (meth) acrylic acid, maleic acid, fumaric acid, itaconic acid,
A monomer having a carboxylic acid group such as citraconic acid and crotonic acid; a monomer having a sulfonic acid group such as vinylsulfonic acid, (meth) allylsulfonic acid, 2-acrylamido-2-methylpropanesulfonic acid, and sulfonated styrene; Monomers having a phosphoric ester group such as a phosphoric acid ester of an alkyl (meth) acrylate can be used, and styrene or a derivative thereof, an alkyl (meth) acrylate,
Vinyl esters such as (meth) acrylonitrile, vinyl acetate and vinyl propionate, and methyl vinyl ether can be used. These monomers can be used alone or in appropriate combination of two or more kinds.

Among hydrophilic polymers composed of these monomers, acrylamide homopolymer,
A copolymer of acrylamide and a cationic vinyl monomer, or a copolymer of acrylamide and an anionic vinyl monomer is preferred, and a copolymer of acrylamide, a cationic vinyl monomer and an anionic vinyl monomer is more preferred.

In order to synthesize the hydrophilic polymer (b), a conventionally known method can be applied. For example, in the presence of an alkyl mercaptan having 6 to 22 carbon atoms, the vinyl monomer is polymerized by a radical polymerization catalyst in a lower alcohol such as methanol, ethanol or isopropyl alcohol, or in a mixture of these lower alcohols and water,
It is obtained by distilling off the lower alcohol after completion of the polymerization. As the radical polymerization catalyst, ammonium persulfate, potassium persulfate, persulfates such as sodium persulfate,
A redox polymerization catalyst obtained by combining these persulfates and a reducing agent, or an azo catalyst such as 2,2'-azobis- (2-amidinopropane) dihydrochloride and 2,2'-azobisisobutyronitrile Can be mentioned. Further, if necessary, a known chain transfer agent may be appropriately used in combination.

The viscosity of the hydrophilic polymer solution (b) thus obtained is 10 to 5000 centipoise in a 20% by weight aqueous solution (however, measured at 25 ° C. at 60 rpm per minute by a Brookfield viscometer). The viscosity is preferably 50 to 1000 centipoise. When this viscosity is lower than 10 centi-boise or higher than 5000 centi-boise, when this is used as the component (b) of the present invention, the storage stability and the functional stability should be those within the above viscosity range. In comparison, they tend to be inferior.

The hydrophilic polymer (b) is used in an amount of 2 to 1 based on 100 parts by weight of the ketene dimer compound represented by the general formula (I).
It is preferable to use 00 parts by weight, preferably 5 to 50 parts by weight.
If the amount is less than 2 parts by weight, the emulsifiability is inferior, and the storage stability and mechanical stability of the internal sizing composition for papermaking are lost. Has a negative effect on effectiveness.

In the present invention, further, a cationized starch having 6 carbon atoms is used.
Polymeric colloids such as cationic, anionic or amphoteric acrylamide polymers obtained by polymerization in the absence of alkyl mercaptans of from 22 to 22; anionic dispersions such as lignin sulfonate and naphthalene sulfonate-formaldehyde condensate A nonionic dispersant such as a dispersant or a sorbitan ester can also be used to such an extent that the stability of the internal sizing composition for papermaking is not impaired.

The internal sizing composition for papermaking of the present invention can be produced by a conventionally known method. For example, the ketene dimer compound and the hydrophilic polymer of (b) and, if necessary, the protective colloid or the dispersant are mixed with an aqueous solvent at a temperature not lower than the melting point of the ketene dimer compound represented by the general formula (I). It is obtained by mixing into a well-known emulsifier such as a homomixer, a high-pressure discharge homogenizer, and an ultrasonic emulsifier.

The thus obtained internal sizing composition for papermaking of the present invention has a particle size of the dispersed phase of 10 μm or less, and exhibits extremely excellent storage stability and mechanical stability at a concentration of 15 to 30% by weight. And an excellent size effect can be exhibited.

The excellent effect of the sizing composition for papermaking of the present invention is that when a vinyl monomer is polymerized or copolymerized in the presence of an alkyl mercaptan having 6 to 22 carbon atoms, the alkyl mercaptan used at the terminal of the obtained polymer is used. Is introduced, whereby the hydrophilic polymer (b) acts as an excellent dispersant and protective colloid of the ketene dimer compound represented by the general formula (I).

The paper-making internal sizing composition of the present invention is characterized in that the ionicity of the hydrophilic polymer (b) is nonionic, cationic,
Storage stability, whether anionic or amphoteric,
It has the advantage of improving mechanical stability and size effect. This enables the ionicity to be appropriately selected and adjusted according to the type and amount of the ionicity of the other additive to be used when used as an internal sizing composition for papermaking.

The internal sizing method of the present invention is carried out by adding the internal sizing composition for papermaking of the present invention to a wet end portion in a paper or paperboard manufacturing process.

Specifically, the paper-making internal sizing composition for papermaking of the present invention is added to the aqueous dispersion of pulp in an amount of 0.002 to 0.002 wt.
3% by weight of solid content, preferably 0.005 to 2% by weight of solid content is added.

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,
Further, starch, polyvinyl alcohol, dye, coating color, surface sizing agent, anti-slip agent and the like may be applied as required by a size press, a gate roll coater, a bill blade coater, a calender or the like.

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

Example 1 In a four-necked flask equipped with a stirrer, a thermometer, a reflux condenser, and a nitrogen gas inlet tube, 12.58 g of dimethylaminoethyl methacrylate, 213.9% aqueous solution of acrylamide 213.9
g, itaconic acid 2.08 g, ion-exchanged water 166.7 g, isopropyl alcohol 212.8 g and normal dodecyl mercaptan
1.62 g was charged and adjusted to pH 4.0 with a 20% aqueous sulfuric acid solution.
While stirring the mixture, nitrogen gas was introduced to remove oxygen, and then the temperature was raised to 60 ° C. At 60 ° C., 3.65 g of a 5% aqueous solution of ammonium persulfate was added to initiate polymerization. Then 7
After the temperature was raised to 8 ° C and kept at 78 ° C for 1.5 hours, 1.10 g of a 5% aqueous solution of ammonium persulfate was added. After maintaining the same temperature for another hour, 200 g of ion-exchanged water was added, and distillation of isopropyl alcohol was started. Two hours after the start of the distillation, a mixed distillate of isopropyl alcohol and water 27 1.
5 g was obtained, and the distillation was completed. 71.5 g of ion-exchanged water was added to the obtained polymerization product, and the nonvolatile content was 20.4%, and the temperature was 6 ° C./min at 25 ° C.
A polymer aqueous solution P-1 having a Brookfield viscosity (hereinafter referred to as viscosity) of 420 centipoise (hereinafter referred to as cps) and a pH of 4.6 measured at 0 rotation was obtained.

Next, 100 parts of a ketene dimer compound (based on a mixture of 40% palmitic acid chloride and 60% stearic acid chloride), 98 parts of the polymer aqueous solution P-1 obtained by the polymerization, and 282 parts of ion-exchanged water were added. 70
° C, pre-dispersed with a homomixer, and kept at the same temperature in a high-pressure discharge homogenizer at 250 kg / cm ^2.
2 passes under a shear pressure of 1 to uniformly disperse. After appropriately adding ion-exchanged water and cooling, the mixture is filtered through a 325-mesh wire gauze, and is an aqueous dispersion of an internal sizing agent composition E for papermaking.
-1 was obtained. This internal sizing composition E-1 for papermaking had a nonvolatile content of 20.2%, a viscosity of 15.4 cps and a pH of 3.5.

In order to examine the storage stability of the internal sizing composition E-1 for papermaking, it was stored at 32 ° C. for one month, and the change over time in viscosity was examined. Further, in order to check the mechanical stability, a stability test was performed using a Marlon method stability tester. Table 2 shows the results of storage stability and mechanical stability.

Examples 2 to 13 Polymerization was carried out in the same manner as in Example 1 except that the type of mercaptan and the composition of the vinyl monomer were changed to those shown in Table 1, to obtain polymer aqueous solutions P-2 to P-13. The amount of isopropyl alcohol for adjusting the viscosity was appropriately changed each time. Next, Example 1 was repeated except that the mixing ratio of the ketene dimer compound / the above polymer was changed as shown in Table 2.
The sizing composition for papermaking E-2 to E-13
And storage stability and mechanical stability were examined for each of them in the same manner as in Example 1. The results are shown in Table 2.

Comparative Examples 1 to 5 Polymer aqueous solutions RP-1 to RP in the same manner as in Examples 2 to 13.
-5, and using the same, the sizing composition for papermaking RE
-1 to RE-5 were obtained, and their storage stability and mechanical stability were similarly examined.

 In addition, the symbol in Table 1 shows the following.

M-1; n-dodecyl mercaptan M-2; n-octyl mercaptan M-3; tert-dodecyl mercaptan M-4; n-hexadecyl mercaptan M-5; n-octadecyl mercaptan M-6; n-butyl mercaptan M -7; thiophenol C-1; dimethylaminoethyl methacrylate C-2; quaternary product of C-1 with methyl chloride C-3; dimethylaminopropyl acrylamide C-4; dimethylaminopropyl methacrylamide A-1; itaconic acid A-2; maleic acid A-3; acrylic acid Comparative Examples 6 to 8 Three types of commercially available internal sizing agents (RE-6 to RE-8) for papermaking containing a ketene dimer compound were used as comparative examples. Table 2 shows the results of examining the physical properties, storage stability, and mechanical stability.

In Table 2, the ketene dimer-based compound was obtained from a mixture of palmitic acid chloride 40% and stearic acid chloride 60% as a raw material, the aqueous polymer solution was described in Table 1, and the storage stability was at 32 ° C. for one month. Is the viscosity. In addition, the mechanical stability is determined by the internal sizing composition for papermaking.
The 50g in Maron method stability tester under a load of 20 Kg / cm ^2, resulting when stirring for 10 minutes at a rotation speed 1000 rpm, 100
This is the weight of the solid component not passing through the mesh wire mesh. The test start temperature is 25 ° C. The larger the solid content weight, the greater the amount of cake generated, indicating that the mechanical stability is poor.

Next, a size effect test was performed using the internal sizing composition for papermaking obtained above.

[Test Example 1] Pulp slurry of 2.4% concentration [LBKP, Canadian
Standard freeness 400ml] with 0.5% sulfuric acid band
Khaotinized starch (Kate F, manufactured by Oji National) 0.3
% Was added sequentially and stirred for 2 minutes. Next, after diluting the pulp slurry concentration to 0.24%, the internal sizing agent compositions E-1 to E-6 for papermaking obtained in Examples 1 to 6 and Comparative Examples 1, 2, 5 to 8 and RE- 1, RE-2, RE-5 to RE-8
0.15% of each, and after stirring for 1 minute, 20% of light calcium carbonate (Tamapearl 121, manufactured by Okutama Kogyo) is added,
After stirring for 1 minute, anionic retention improver (High Reten 50
1, Dick Hercules) 0.02%
Stirred for minutes. Using the stock obtained in this way,
Noble and Wood handmade equipment, basis weight 70g /
m ₂ wet paper was obtained. The papermaking pH was 8.0. This wet paper was pressed until the moisture content became 58.0%, and then dried at 80 ° C. for 70 seconds with a drum dryer. Immediately after drying, moisture content 3.5
% Paper was obtained. The paper was conditioned in an atmosphere of 20 ° C and a relative humidity of 65% for 24 hours.
It was measured according to 122. 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.

[Test Example 2] 2.4% pulp slurry [LBKP, Canadian
Standard freeness 400ml] with 0.5% sulfuric acid band
Cationized starch (Kate F, manufactured by Oji National) 0.3
% Was added sequentially and stirred for 2 minutes. Then, after diluting the pulp slurry concentration to 0.24%, each of the paper-making internal sizing composition obtained in Examples 7 to 13 and Comparative Examples 3 to 8 was used.
0.16% and 0.02% of a cationic retention aid (Hiretene 104, manufactured by Dick Hercules) were added, and the mixture was stirred for 1 minute. Using the thus obtained paper stock, the same operation as in Test Example 1 was performed, and the degree of Stigecht sizing of handmade paper having a basis weight of 70 g / m ² was measured. Table 4 shows the results.

From the above results, it can be seen that the internal sizing composition for papermaking of the examples is excellent in storage stability and mechanical stability, and that the internal sizing method using the same exhibits an excellent sizing effect.

Effects of the Invention According to the present invention, since a hydrophilic polymer obtained by polymerizing or copolymerizing a vinyl monomer in the presence of an alkyl mercaptan having 6 to 22 carbon atoms is used in combination with a ketene dimer compound, an internal sizing agent for papermaking is used. The composition is excellent in storage stability and mechanical stability, and the internal sizing method using the composition can exhibit an excellent size effect.

────────────────────────────────────────────────── ─── Continued from the front page (72) Inventor Mayumi Narishima 17-2 Yawata Kaigandori, Ichihara City, Chiba Prefecture Inside Dick Hercules Co., Ltd. (56) References JP-A-63-42995 (JP, A) 60-258245 (JP, A) U.S. Pat. No. 4,425,469 (US, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) D21H 17/00-17/74

Claims (4)

(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 vinyl monomer is polymerized or copolymerized in the presence of an alkyl mercaptan having 6 to 22 carbon atoms. An internal sizing composition for papermaking, comprising: a hydrophilic polymer; and 2 to 100 parts by weight of the hydrophilic polymer of (b) based on 100 parts by weight of the compound of (a). 2. The internal additive for papermaking according to claim 1, wherein the alkyl mercaptan having 6 to 22 carbon atoms in (b) is present in an amount of 0.01 to 10 mol% based on the vinyl monomer. Sizing composition. 3. The polymer of (b) wherein the hydrophilic polymer is acrylamide, a copolymer of acrylamide and a cationic vinyl monomer, a copolymer of acrylamide and an anionic vinyl monomer, or a copolymer of acrylamide and a cationic vinyl monomer. The paper-making internal sizing composition according to claim 1 or 2, wherein the sizing composition is a copolymer of styrene and an anionic vinyl monomer. 4. An internal sizing method using the internal sizing composition for papermaking according to any one of claims 1 to 3.