JPH0127200B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a ketene dimer sizing agent. Aqueous dispersions obtained by dispersing ketene dimers in water in the presence of dispersants are well known as sizing agents for cellulosic fiber products such as paper, paperboard, wood fiberboard, and the like. This sizing agent produces a sizing effect by directly reacting the ketene dimer with cellulose fibers, but the drawback is that it takes more time to develop this effect than other sizing agents. In particular, this difficulty causes fatal problems when surface sizing or pigment coating is applied on-machine to the above-mentioned product after papermaking. The present inventors have conducted various studies with the aim of solving the drawbacks of the above-mentioned known ketene dimer-based sizing agents, and providing a sizing agent that can particularly impart excellent sizing effects to products immediately after drying. It has been found that a sizing agent prepared using the following specific dispersant meets the above objective. The present invention was completed based on this knowledge. The present invention provides a sizing agent comprising a dispersed phase containing a ketene dimer and an aqueous continuous phase containing a dispersant,
The above dispersant is () an anionic dispersant selected from naphthalene sulfonate-formaldehyde condensate and lignin sulfonate, and () general formula [In the formula, R ¹ is a hydrogen atom or a methyl group, R ² and R ³ are the same or different and are a hydrogen atom, a lower alkyl group, a hydroxyethyl group, a cyanoethyl group, a benzyl group, or a cyclohexyl group, and X ^- is an organic acid or This invention relates to a ketene dimer-based sizing agent characterized by containing a copolymer of an ammonium salt represented by the following formula and sulfur dioxide. In the sizing agent of the present invention, various known ketene dimers or mixtures thereof with extenders can be used as the dispersed phase. Typical examples of ketene dimers that can be advantageously used include those represented by the following formula. In the above formula, R ₁ and R ₅ each represent a hydrocarbon residue having 8 to 30 carbon atoms, preferably 10 to 20 carbon atoms. Examples of this hydrocarbon residue include alkyl groups such as decyl, undecyl, dodecyl, tridecyl, tetradecyl, pentadecyl, hexadecyl, heptadecyl, octadecyl, and eicosyl groups, decenyl, tridecenyl, hexadecenyl, octadecenyl,
Alkenyl groups such as eicosenyl groups, alkaryl groups such as p-tert-butylphenyl, octylphenyl, nonylphenyl, dodecylphenyl groups, alkyl-substituted cycloalkyl groups such as nonylcyclopropyl and dodecylcyclohexyl groups, aralkyl groups such as phenylethyl groups. Examples include groups, among which alkyl groups are preferred. The above ketene dimers can be used alone or in combination of two or more. Extending agents that can be mixed with ketene dimer include:
These include amorphous hydrocarbon resins, rosin esters, etc., which are mixed with ketene dimer and co-dispersed in water in the form of a mixture, thereby improving the stability, especially mechanical stability, of the resulting dispersion. can be improved, but the size effect is not positive. Therefore, it is appropriate that the proportion of these extenders used is about 60% or less, preferably 5 to 50%, based on the total weight with the ketene dimer. There are no particular restrictions on the rosin ester used in combination with the ketene dimer, provided that it is not excessively polar and has compatibility with the ketene dimer, but it usually has an acid value of 30 or less (JIS K 0070) and a rosin ester of 100 or less. Those having a hydroxyl value (JIS K 0070) are preferred. As is well known, rosin ester is
It is an ester of various rosins and monohydric or polyhydric alcohols, and gum rosin, udon rosin, tall oil rosin, modified products thereof, and mixtures thereof are generally used as the rosin. Examples of the modified product include those subjected to treatments such as hydrogenation, disproportionation, polymerization, and aldehyde modification. Alcohols include monohydric alcohols with 1 to 20 carbon atoms, especially 1 to 12 carbon atoms, ethylene glycol, propylene glycol, butanediol, neopentyl glycol, hexanediol, glycerin, trimethylolethane, trimethylolpropane, pentaerythritol, diglycerin, etc. of polyhydric alcohols are used. The softening point (ring and ball method) of the produced ester ranges from liquid to 120° C. depending on the type of alcohol, degree of esterification, etc., and any of these can be preferably used in the present invention.
In addition, the amorphous hydrocarbon resin used in combination with the ketene dimer should be compatible with the ketene dimer, have a softening point of 150°C, preferably 120°C or less, and be non-crystalline. There are no restrictions, and various natural or synthetic hydrocarbon resins, typically those obtained by polymerizing or copolymerizing ethylenically unsaturated hydrocarbons by radical polymerization, cationic polymerization, anionic polymerization, thermal addition polymerization, etc., or hydrogenation thereof. Can give examples of things. The amorphous hydrocarbon resin has an average molecular weight (last method) of 300 to
A value of about 3000, preferably about 400 to 2000, is suitable. As the molecular weight decreases, the effect of imparting water resistance tends to gradually decrease.On the other hand, when the molecular weight becomes too high, the compatibility tends to decrease and dispersion becomes difficult. The ethylenically unsaturated hydrocarbons used in the production of the above-mentioned amorphous hydrocarbon resins include (a) olefins or diolefins obtained from the petrochemical industry; aliphatic or Cyclic olefins Aliphatic or cyclic diolefins such as butadiene, isoprene, piperylene, cyclopentadiene, dicyclopentadiene, etc. Aromatic olefins such as styrene, α-methylstyrene, vinyltoluene, indene, isopropenyltoluene (b) Terpenes α-pinene, β - Examples include pinene, camphein, and dipentene. In the present invention, it is essential to use the following two types of dispersants in combination. () At least one anionic dispersant selected from naphthalene sulfonate-formaldehyde condensate and lignin sulfonate. Examples of the above-mentioned sulfonate salts include potassium salts and soda salts. The above-mentioned anionic dispersant () is generally used in an amount of about 0.2 to 5% (wt%, the same applies hereinafter unless otherwise specified), preferably about 0.5 to 3%, based on the ketene dimer or this and extender (hereinafter referred to as dispersant). If it is less than 0.2%, the stability of the dispersion, especially the storage stability, is still insufficient.
If it exceeds 5% by weight, there is no particular advantage, and the size effect tends to decrease. () A cationic dispersant comprising a copolymer of an ammonium salt represented by the following general formula (2) and sulfur dioxide. [In the formula, R ¹ represents a hydrogen atom or a methyl group.
R ² and R ³ are the same or different hydrogen atoms;
It represents a lower alkyl group such as methyl, ethyl, propyl, butyl, hexyl, etc.; a hydroxyethyl group; a cyanoethyl group; a benzyl group or a cyclohexyl group. X ^- is Cl, Br, I, HCOO,
_{CH3COO , H2PO4} , _HSO4 , _HSO3 , _{CH3SO4 ,}
Represents an anion of an organic or inorganic acid such as NO ₃ . ] Specific examples of the ammonium salt represented by the above general formula (2) include the following compounds. Diallylamine hydrochloride Methyldiallylamine hydrochloride Dimethyldiallylammonium chloride Diethyldiallylammonium chloride Dipropyldiallylammonium chloride Methylethyldiallylammonium chloride Methylpropyldiallylammonium chloride Methyl-(2-cyanoethyl)diallylammonium chloride Ethyl-(2-hydroxyethyl) Diallylammonium chloride Methylbutyldiallylammonium chloride Methylbenzyldiallylammonium chloride Methylcyclohexyldiallylammonium chloride and corresponding ammonium salts of other acids and corresponding dimethallylammonium salts The copolymers to be used as the cationic dispersant () are, for example, those mentioned above. It can be obtained by polymerizing an ammonium salt represented by the general formula (2) and sulfur dioxide in a solvent such as water, dimethyl sulfoxide, dimethyl formamide, etc. in the presence of a radical polymerization catalyst. The polymerization reaction is described, for example, in Japanese Patent Publication No. 45-343.
The method described in Japanese Patent Publication No. 45-1457 may be followed. The copolymerization ratio of the raw material monomers is preferably in the range of about 5 to 50 mol% of sulfur dioxide. Also, the intrinsic viscosity of the obtained copolymer (30
°C, 5 g of copolymer - 100 ml of N/10 - in NaCl)
is preferably in the range of about 0.03 to 5. If the intrinsic viscosity is less than 0.03, the action as a dispersant is still insufficient, and if it exceeds 5, the flocculating action tends to be greater than the dispersing action. The above-mentioned cationic dispersant (2) is usually used at a ratio of about 2.5 to 100%, preferably about 5 to 50%, based on the material to be dispersed, and this usage range is a characteristic of the sizing agent of the present invention. The size effect of cellulose products immediately after drying can be significantly improved. If the amount used is outside the above range, the stability of the dispersion itself will decrease, and the above effects will also tend to decrease. The dispersant of the present invention contains the above-mentioned cationic dispersant () in an amount of about 2.5% or more, preferably about 5%, based on the weight of the material to be dispersed.
On the premise that the above is used, the following known cationic dispersants () can be used in combination.
In this case, it is preferable that the total amount of the dispersant () and the dispersant () used is about 10 to 150% of the material to be dispersed. Examples of known cationic dispersants that can be advantageously used in combination include cationic starch containing primary, secondary, tertiary or quaternary amino groups. More specifically, the cationized starch () is made by decomposing starch of corn, tapioca, potato, wheat, etc. with hydrogen peroxide, sodium hypochlorite, enzymes, etc., and then adding a cationizing agent such as diethylaminoethyl chloride. Examples include those that have been cationically modified by reaction, or those that have been further added with ethylene oxide, propylene oxide, etc. to improve dispersibility. The sizing agent of the present invention is manufactured according to a conventional method. For example, the above-mentioned material to be dispersed is heated and melted at a temperature of about 100° C. or lower, preferably about 80° C. or lower, and dispersed in water in the presence of a dispersant. The aqueous dispersion thus obtained usually contains up to 30% by weight of ketene dimer or a mixture thereof with an extender, preferably from 10 to 20% by weight.
The particle size of the dispersed phase composed of the mixture is about 1 μm or less, and has very good stability, and can be used as it is or after further dilution as the sizing agent of the present invention. The ketene dimer-based sizing agent of the present invention can be used not only for paper making of cellulose fibers, but also for the production of cellulose fibers, mineral fibers such as asbestos, rock wool, etc., synthetic fibers such as polyamide, etc.
It can be advantageously applied to the production of paper, paperboard, fiberboard, etc. by forming a mixture with polyester, polyolefin, etc. For example, when the sizing agent of the present invention is applied to internal sizing, it is added to an aqueous slurry of cellulose fibers, usually from about 0.005 to
3% by weight, preferably about 0.01-2% by weight. In addition, for the above-mentioned internal addition sizing, a normal cationic polymer is added to the fiber in an amount of about 0.001 to 3% by weight, preferably about 0.005 to 1% by weight on a dry weight basis.
They can also be used in combination. According to this, the effect of the ketene dimer-based sizing agent of the present invention can be further increased. As this cationic polymer, the above-mentioned cationic dispersants can be used, but more preferably, cationic dispersants such as acrylamide-dimethylaminoethyl methacrylate copolymer, Mannitz modified polyacrylamide, and Hofmann decomposition product of polyacrylamide are used. It is preferable to use an acrylamide copolymer, an amphoteric acrylamide copolymer polyamide polyamine epichlorohydrin resin, or the like. In addition, the ketene dimer sizing agent of the present invention is
It is also possible to apply or impregnate paper, paperboard, wood fiberboard, etc. for surface sizing of such products. Thus, the sizing agent of the present invention eliminates all the serious drawbacks of this type of ketene dimer-based sizing agent known in the past, and can quickly exhibit a sizing effect after papermaking.
Excellent size effects can be imparted to the product immediately after drying. Examples and comparative examples will be given below to further clarify the features of the present invention. For example, it represents the middle part or the weight part. Example 1 88.2 parts of mixed alkyl ketene dimer (made from a mixture of 70% palmitic acid chloride and 30% stearic acid chloride), 10 parts of a 10% aqueous solution of naphthalene sulfonic acid soda formaldehyde condensate, dimethyldiallylammonium chloride and dioxide Copolymer with sulfur (intrinsic viscosity 1.2)
368 parts of a 10% aqueous solution and 340 parts of soft water were heated to 70℃ and predispersed in a homomixer, then homogenized while maintaining the same temperature (shear pressure 300Kg/cm ² ).
was passed twice for dispersion. After cooling, it was filtered through a 350-mesh wire mesh to obtain an aqueous dispersion (sizing agent No. 1). This product had a nonvolatile content of 15.2%, a pH of 3.0, and a viscosity (at 25°C) of 15 cps. In addition, 10% of cationized starch (N content 0.5%) was prepared by steaming part (Sizing Agent No. 2 to 4) or all (Comparative Example, Sizing Agent No. 5) of the aqueous solution of the copolymer used above. Aqueous solution (viscosity at 25℃: 30cps)
An aqueous dispersion of alkyl ketene dimer was obtained in the same manner. The thus obtained aqueous dispersion of ketene dimer and a commercially available ketene dimer sizing agent (manufactured by Company H, nonvolatile content 15.7%, PH 4.2, viscosity (25° C.) 30 cps) were each evaluated as a sizing agent for paper manufacturing. That is, to a 1% aqueous slurry of pulp (L-BKP, 500 ml CSF), calcium carbonate was added at 20% to the pulp, sulfate was added to the pulp at 1%, and each of the above aqueous dispersions was added at 0.15% to the pulp (in terms of non-volatile content). Add 0.05% of a copolymer of acrylamide and acrylic acid (95 mol/5 mol) to the pulp (pH 6, 3% aqueous solution with a viscosity of 6000 cps at 25°C), stir well, and then use a Tatsupi Standard Sheet Machine. Using this method, paper was made to have a basis weight of 65±1 g/m ² . The obtained wet paper was dehydrated for 5 minutes at 10 kg/cm ² and dried for 1 minute in a rotary dryer (100° C.). Furthermore, the paper stock was conditioned for 24 hours at 20°C and 65% RH. The Steckigt sizing degree (JIS P 8122) was measured for the paper stock immediately after drying (1 hour later) and after humidity conditioning. In addition, the ash content of the paper stock after humidity conditioning (electric furnace, 500
℃ × 3 hours) was measured. The results obtained are shown in Table 1 below for each sizing agent.

[Table] The values in parentheses for size in Table 1 are as follows:
The results of measuring the degree of sizing when each sizing agent was kept at 30° C. for one month and then the same test as above was repeated to make paper are shown. From Table 1 above, it is clear that the sizing agents of the present invention can exhibit superior sizing effects compared to commercially available products, and in particular can exhibit significantly improved sizing effects when drying directly. . Furthermore, it can be seen that the above-mentioned effects can be stably exhibited in substantially the same way even after the sizing agent has been stored for one month. Example 2 88.2 parts of the mixed alkyl ketene dimer used in Example 1, 10 parts of a 10% aqueous solution of sodium lignin sulfonate, and a copolymer of dimethyldiallylammonium chloride and sulfur dioxide (intrinsic viscosity 1.8)
Example 1 using 368 parts of a 10% aqueous solution of and 340 parts of soft water.
An aqueous dispersion (sizing agent No. 8) was obtained in the same manner as above. This product has a nonvolatile content of 15.4%, a pH of 2.9, and a viscosity of 25%.
℃）26 cps. As a result of using this aqueous dispersion as a sizing agent in the same manner as in Example 1, the sizing degree of the obtained paper stock immediately after drying and after humidity conditioning was 19.4 seconds and 25.5 seconds, respectively, and the ash content was 15.5 seconds. It was %. Examples 3 to 5 In the above Example 2, a copolymer of diallylamine hydrochloride and sulfur dioxide (intrinsic viscosity 0.7) was used instead of the copolymer used (Example 3), and a copolymer of dimethyldimethacrylammonium chloride and sulfur dioxide was used instead of the copolymer used. A copolymer (intrinsic viscosity 0.5) with (Example 4),
In addition, aqueous dispersions (sizing agents No. 9 to 11) were obtained in the same manner using copolymers of diethyl diallylammonium chloride and sulfur dioxide (intrinsic viscosity 0.9) (Example 5). Table 2 shows the results of paper making in the same manner as in Example 1 using each of the obtained sizing agents. Table 2 also shows the results using the sizing agent obtained in Example 2 above.

[Table] It is clear from Table 2 above, as in Table 1, that the sizing agent of the present invention exhibits excellent sizing effects. Example 6 71.4 parts of a mixture (mixing ratio 90:10) of the mixed alkyl ketene dimer used in Example 1 and hydrogenated petroleum resin (softening point 70°C), 8 parts of a 10% aqueous solution of naphthalene sulfonic acid soda formaldehyde condensate , 178 parts of a 10% aqueous solution (viscosity (25°C) 30 cps) of cationized starch (N content 0.5%) with propylene oxide added (2%) and steamed.
Various aqueous dispersions (sizing agents No. 12 to 16) were prepared in the same manner as in Example 1 using 100 parts of a 10% aqueous solution of a copolymer of dimethyldiallylammonium chloride and sulfur dioxide having various intrinsic viscosities and 280 parts of soft water. Obtained.
For comparison, an aqueous dispersion (sizing agent No.
17). The above aqueous dispersion was added to a 1% aqueous slurry of pulp (L-BKP) at 0.15% (based on nonvolatile content) based on the pulp, and then paper was made using a Tatsupi Standard Sheet Machine. Thereafter, in the same manner as in Example 1, the Steckigt sizing degree of the paper stock was measured after 1 hour of drying and after humidity conditioning. The results are shown in Table 3.
Table 3 shows the case where the same commercially available ketene dimer sizing agent (Sizing agent No. 6) used in Example 1 was used in place of the above sizing agent, and the case where no aqueous dispersion was used. (blank) results are also listed.

[Table] As with Tables 1 and 2, it is clear from Table 3 above that the use of the sizing agent of the present invention provides a significantly improved sizing effect. Comparative Example 1 In Example 6, the poly(diallylamine)-epihalohydrin resin described in Examples 1 and 3 in JP-A-52-110906 was used instead of the copolymer of dimethyldiallylammonium chloride and sulfur dioxide. Aqueous dispersions (sizes No. 18 and 19) were obtained in the same manner using each of the following. Each aqueous dispersion obtained in Example 6 and Comparative Example 1 (Sizing agent No. 13 and 14 and Sizing agent No. 18 and 19)
The mechanical stability, storage stability, and size effect were investigated according to the following methods. Γ Mechanical stability: Collect 50 g of each aqueous dispersion immediately after preparation into a 100 ml beaker, and stir the liquid in the beaker with a magnetic stirrer (length 3 cm) at 500 rpm.
The sample was rotated and the presence or absence of gelation was observed. Γ Standing stability: After each aqueous dispersion was left to stand at 30°C for one month, the presence or absence of gelation was observed. Γ size effect: Each aqueous dispersion immediately after preparation and after being left at 30°C for 10 days was converted into pulp (L-BKP).
was added to a 1% aqueous slurry at a ratio of 0.15% (in terms of nonvolatile content) to the pulp, and then paper was made using a Tatsupi Standard Sheet Machine, followed by drying for 1 hour and humidity conditioning in the same manner as in Example 1. The Steckigt sizing degree of the stock was measured. The results are shown in Table 4 below.

【table】

Claims (1)

[Scope of Claims] 1. A sizing agent comprising a dispersed phase containing a ketene dimer and an aqueous continuous phase containing a dispersant, wherein the dispersant is selected from () naphthalene sulfonate-formaldehyde condensate and lignin sulfonate. Anionic dispersant, and () general formula [In the formula, R ¹ is a hydrogen atom or a methyl group, R ² and R ³ are the same or different and are a hydrogen atom, a lower alkyl group, a hydroxyethyl group, a cyanoethyl group, a benzyl group, or a cyclohexyl group, and X ^- is an organic acid or A ketene dimer-based sizing agent containing a copolymer of an ammonium salt represented by the following formula and sulfur dioxide: 2. The sizing agent according to claim 1, wherein the dispersant further contains () cationized starch in addition to the above components () and ().