JPS5951637B2 - Keten dimer-based sizing agent - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a ketene dimer sizing agent suitable for sizing cellulose fibers.

Cellulose fiber products such as paper, paperboard, and wood fiberboard are generally made by adding a sizing agent to an aqueous dispersion of cellulose fibers. Rosin-based sizing agents are widely used because of their ability to impart properties such as properties. However, the above-mentioned rosin-based sizing agents do not exhibit their desired effect unless they are used in combination with sulfate band and are not fixed to the cellulose fibers by the sulfate band. Therefore, papermaking in an acidic region is essential.

This is accompanied by various problems such as deterioration in the quality of the paper-made product, complicated wastewater treatment, and corrosion of the paper-making machine, and also imposes severe restrictions on the use and processability of the obtained product. In addition, in order to improve paper quality such as opacity and whiteness,
Filler is added internally, but when basic filler, especially cheap calcium carbonate, is used, the calcium carbonate decomposes during papermaking in the acidic region, not only does it not help improve the original paper quality, but also carbonate There is a disadvantage that gas is generated, which interferes with papermaking. On the other hand, as a sizing agent that does not require papermaking in an acidic region, a ketene dimer-based sizing agent in which ketene dimer is dispersed in water using a dispersant has been known.

This can directly react with cellulose fibers and impart water resistance to the fibers without using a sulfuric acid band. Therefore, papermaking in a neutral range is possible, and the above-mentioned disadvantages associated with papermaking in an acidic range can be avoided. It has the advantage of being able to eliminate However, this ketene dimer-based sizing agent has the fatal drawback that its aqueous dispersion itself is inherently unstable and has poor storage stability, mechanical stability, chemical stability, etc. In other words, ketene dimer, which can be used as a sizing agent, is itself highly crystalline, and when it is dispersed in water to form an aqueous dispersion, crystallization occurs in the dispersed phase particles in a short period of time. , which tends to cause the particles to rapidly break up and precipitate out in the dispersion. Further, the above aqueous dispersion may contain, for example, 3
When mechanically applied after storage at a low temperature of about 10° C., it easily gels and is no longer restored to its original dispersion.
Various attempts have been made to improve the stability of the aqueous ketene dimer dispersion, and some dispersions commercially available as sizing agents have excellent stability.

However, on the other hand, this commercially available product has an extremely low size effect and is not practically satisfactory. Furthermore, known ketene dimer-based sizing agents have disadvantages in that they reduce the strength of cellulose fiber products obtained using them, such as the bursting strength of paper, and also reduce the coefficient of friction. It has the disadvantage of being expensive. The present inventors have investigated various methods for the above-mentioned ketene dimer-based sizing agent, which is capable of papermaking in the neutral range as described above, but has problems particularly with its stability and cannot exhibit satisfactory performance in practical use. As a result of repeated research, when a mixture of ketene dimer and rosin ester is used as a dispersed phase, it is extremely stable and satisfies practical requirements including size effect (water resistance).
It was discovered that an aqueous dispersion having various properties can be obtained. However, as is well known, the size effect of the above rosin esters is extremely poor, and when such rosin esters are used together, the size effect naturally decreases, and the size effect 2 is improved by their combined use. Conventionally, this was completely unthinkable. The present invention has extremely excellent stability by mixing rosin ester, which has not been used in the past, with ketene dimer and dispersing it in water. No,
The present invention has succeeded in providing a new sizing agent that does not substantially reduce the size effect. That is, the present invention provides a ketene dimer-based sizing agent comprising a dispersed phase containing a ketene dimer and an aqueous continuous phase containing a dispersant, wherein the dispersed phase is a mixture of ketene dimer 31 and rosin ester. Related to sizing agents. The ketene dimer-based sizing agent of the present invention has significantly improved storage stability, mechanical stability, and chemical stability, and does not break or disperse dispersed phase particles even after long-term storage. There is no risk of gelation of the liquid.

Furthermore, the sizing agent of the present invention can impart excellent sizing effects and water resistance to cellulose fiber products. These characteristics are
It is first expressed by dispersing a mixture of ketene dimer and rosin ester in water and forming a dispersed phase. Even though ketene dimer and rosin ester are used, when mixing the dispersion after dispersing each of them alone, the stability of the resulting mixed dispersion is not improved, and the size effect only affects the mixed dispersion. It only depends on the amount of ketene dimer present in the rosin ester dispersion, and inevitably decreases as the amount of rosin ester dispersion mixed increases. Furthermore, the sizing agent of the present invention enables paper forming in the neutral range, which is a feature of ketene dimer-based sizing agents, and also substantially prevents the reduction in product strength and friction coefficient that is seen with known ketene dimer-based sizing agents. Not accompanied by

In addition, the water resistance imparting effect of the sizing agent of the present invention is expressed immediately after papermaking, and therefore manufacturing control and subsequent processing of the product are easy. In addition, the sizing agent of the present invention can be manufactured at a lower cost than known ketene dimer-based sizing agents, and its use is economically preferable. As the ketene dimer constituting the sizing agent of the present invention, any of various known ketene dimers can be used.

The ketene dimer is typically represented by the following formula. In the above formula, R1 and R2 each have 8 to 30 carbon atoms, preferably 10
~20 hydrocarbon residues are shown.

Examples of this hydrocarbon residue include decyl, undecyl,
dodecyl, tridecyl, tetradecyl, pentadecyl,
Alkyl groups such as hexadecyl, heptadecyl, octadecyl, and eicosyl groups, alkenyl groups such as decenyl, tridecenyl, hexadecenyl, octadecenyl, and eicosenyl groups, and alkaryl groups such as P-tertiarybutylphenyl, octylphenyl, nonylphenyl, and dodecylphenyl groups. Examples thereof include alkyl-substituted cytaloalkyl groups such as nonylcyclopropyl and dodecylcyclohexyl groups, and aralkyl groups such as phenylethyl, and among these, alkyl groups are preferred. The above ketene dimers can be used alone or in combination of two or more. In addition, in the present invention, the rosin ester used in combination with the above ketene dimer is not particularly limited as long as it is not excessively polar and has compatibility with the ketene dimer, but it usually has an acid value of 30 or less (JIS KOO7O) and an acid value of 100 or less. Hydroxyl value (J
ISKOO7O) is preferred.

As is well known, rosin esters are esters 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 products include those subjected to treatments such as hydrogenation, disproportionation, polymerization, and aldehyde modification. Alcohols include monohydric alcohols having 1 to 20 carbon atoms, especially 1 to 4 carbon atoms, ethylene glycol, propylene glycol, butanediol, neopentyl glycol, hexanediol, glycerin, trimethylolethane, trimethylolpucapane, pentaerythritol, Polyhydric alcohols such as diglycerin are used. The softening point (ring and ball method) of the produced ester ranges from liquid to about 120°C depending on the type of alcohol, degree of esterification, etc., and any of these can be preferably used in the present invention. Although the ratio of ketene dimer and rosin ester used in the sizing agent of the present invention is not limited, it is usually 40% of ketene dimer.
-96% by weight preferably 50-952% by weight and rosin esters 4-60% by weight preferably 5-50% by weight
It is appropriate to

If the amount of ketene dimer exceeds 96% by weight, the desired effect of mixing the rosin ester will not be noticeable, especially the stability of the dispersion will decrease, and if the amount is too much less than 40% by weight, water resistance will not be imparted. The effect is reduced, which is not desirable. The sizing agent of the present invention can be prepared, for example, by heating and melt-mixing the above-mentioned ketene dimer and rosin ester at a temperature of about 100° C. or lower, preferably about 80° C. or lower, and then melting the molten mixture. ' can be produced by dispersing ' in water in the presence of a dispersant.

The temperature during the above dispersion is usually about 50 to 80°C. If the temperature is too high, hydrolysis of the ketene dimer may occur. In the above, as the dispersant, a known cationic dispersant or/and a nonionic dispersant and/or anionic dispersant can be advantageously used. Specifically, the cationic dispersant is preferably a cationized starch containing a primary, secondary, tertiary or quaternary amino group, and also polyethyleneimine, polyethyleneimine-epichlorohydrin condensate, aminopolyamide epichlorohydrin resin, polyvinylpyridine, Styrene-dimethylaminoethyl methacrylate copolymer, cationic polyurethane resin, dicyandiamide formaldehyde resin, urea formaldehyde resin, melamine formaldehyde resin,
Dimethylamine epichlorohydrin resin and the like can also be used. Cationized starches that can be advantageously used include, for example, starches of corn, tapioca, potato, wheat, etc., which are decomposed with hydrogen peroxide, sodium hypochlorite, etc., and then reacted with a cationizing agent such as diethylaminoethyl chloride to undergo cation modification. For example, ethylene oxide, propion oxide, etc. may be added thereto to improve dispersibility. Further, examples of nonionic dispersants that can be used in combination with the above-mentioned cationic dispersant include polyvinyl alcohol and oxidized starch, and examples of anionic dispersants include naphthalenesulfonic acid and sodium formaldehyde condensates and ligninsulfonic acid sodium. The above-mentioned dispersant is usually used in an amount of 10 to 100% by weight, preferably 15 to 50% by weight, based on the mixture of ketene dimer and rosinister, whereby an aqueous dispersion with a good dispersion state can be obtained.

The aqueous dispersion thus obtained usually contains up to 30% by weight, preferably 10 to 20% by weight, of a mixture of ketene dimer and rosin ester, and the particle size of the dispersed phase composed of the mixture is about 1 μm or less; It has very good stability and can be used as a sizing agent as it is or after further dilution.

The ketene dimer-based sizing agent of the present invention can be used not only to make paper from cellulose fibers, but also from a mixture of the fibers and mineral fibers such as asbestos, rock wool, etc. or synthetic fibers such as polyamide, polyester, polyolefin, etc., to produce paper, paperboard, etc. , which can be advantageously applied when manufacturing fiberboards and the like.

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 in an amount of usually 0.005 to 3% by weight, preferably 0.01 to 2% by weight based on the dry weight of the fibers. Ru.

Further, in the above-mentioned internal addition sizing, a conventional cationic polymer can be added in an amount of 0.001 to 3% by weight, preferably 0.005 to 1% by weight, based on the dry weight of the fiber. According to this, the effect of the ketene dimer-based sizing agent of the present invention can be further increased. As the cationic polymer, the above-mentioned cationic dispersants can be used, but preferably, cationic polymers such as acrylamide dimethylaminoethyl methacrylate copolymer, Mannitz modified polyacrylamide, and Hofmann decomposition product of polyacrylamide are used. It is preferable to use an amphoteric acrylamide copolymer or an amphoteric acrylamide copolymer. The ketene dimer sizing agent of the present invention can also be applied to or impregnated onto paper, paperboard, wood fiberboard, etc. to perform surface sizing of such products.

Examples are given below to clarify the features of the present invention.

Examples Middle part and percentage are based on weight unless otherwise specified. Example 1 Ketene dimer (KD) Mixed alkyl ketene dimer ester A obtained by reacting a mixture of palmitic acid talolide (70%) and stearic acid chloride (30%) in the presence of triethylamine in benzene. Acid value 7, hydroxyl group. Value 0, viscosity (25℃) 3000CPS (
7): Hydrogenated rosin methyl ester.

A dispersant made by steaming cationized starch (N content 0.5%) and having a 10% aqueous solution viscosity (25°C) of 30 CPS.

(The above KD and ester A were heated and mixed in the weight ratios listed in Table 1, and 50 g of the mixture, 125 g of a 10% aqueous solution of the above dispersant, and 290 g of distilled water were heated to 70°C and predispersed using a homomixer. Homogenizer (while keeping the temperature)
It was passed through a shearing pressure of 350 kg/CIn twice for dispersion. After cooling, it was filtered through a 350-mesh wire mesh to obtain an aqueous dispersion. There was almost no filtrate in any case, and it was less than 0.007%. For comparison, aqueous dispersions were obtained in the same manner as above using KD and Ester A alone.

4 The non-volatile content, state and viscosity of these aqueous dispersions are about 15%, 4.2-4.5 and 10-15C, respectively.
PS, and its particle size was 0.5μ or less. The following stability tests were conducted on the various aqueous dispersions mentioned above. Method (a) Weigh out 50 g of the aqueous dispersion just prepared in a 100 ml beaker, place the beaker on a magnetic stirrer, and stir the stirrer (length 3 cm) into a 500 ml beaker. P. M. The sample was rotated and the presence or absence of gelation was observed.

Method (Example) The aqueous dispersion immediately after preparation was stored at 5° C. for 24 hours and then left at room temperature for 24 hours.

This aqueous dispersion was tested in the same manner as in method (a) above. These results are shown in Table 1 below.

The above seven types of aqueous dispersions and commercially available ketene dimer aqueous dispersions (non-volatile content 16.2%, Tf] 3.6, viscosity 8 cp
S) was used as a paper sizing agent.

A paper stock was produced as follows. That is, 435 ml of Canadian Standard Freeness pulp (L-BKP
) of the above aqueous dispersion to a 1% aqueous slurry of pulp.
After adding at a rate of 3% (non-volatile content),
Basis weight 60±1g using standard sheet machine
/m nitrogen.

The obtained wet paper was dehydrated for 5 minutes at 3 kg/Cnl2, dried for 1 minute in a rotary dryer (100°C), and then the paper stock was
°C, 65% R.C. H. Humidity was controlled for 24 hours under these conditions. For these paper stocks, the Steckigt size degree (JISP8l22
), specific bursting strength (JISP8ll2) and coefficient of friction (J
ISC6244) was measured.

The results are shown in Table 2 below. Table 2 also shows, for comparison,
Mixed aqueous dispersions obtained by blending an aqueous dispersion of KD and an aqueous dispersion of ester A at weight ratios of 80:20 and 60:40 were used as sizing agents Haruka a and ▲b, respectively, and the same procedure was carried out. The results of the tests are also listed.

However, "commercial product note" in the table indicates the case where it is added at a ratio of 0.5% (in terms of non-volatile content) to the pulp.

Example 2 Ester B Rosin pentaerythritol ester ester C with acid value 18, hydroxyl value 23, softening point 105°C Disproportionated rosin glycerin ester ester D with acid value 5, hydroxyl value 48, softening point 98°C Acid value 7, Rosin glycerin ester dispersant with a hydroxyl value of 44 and a softening point of 82°C A 10% aqueous solution made by steaming cationized starch (N content 0.5%) with propylene oxide added (2% to cationized starch) The viscosity (25℃) of
cps Example 1 In place of ester A, the above-mentioned various rosin esters were used in the proportions shown in Table 3, and in place of dispersant A, dispersant B was used, and in the same manner, a ketene dimer-based sizing agent was prepared. An aqueous dispersion was obtained.

Claims (1)

[Scope of Claims] 1. A ketene dimer-based paper sizing agent comprising a dispersed phase containing a ketene dimer and an aqueous continuous phase containing a dispersant, characterized in that the dispersed phase is a mixture of a ketene dimer and a rosin ester. A ketene dimer-based paper sizing agent. 2 The weight ratio of ketene dimer and rosin ester is 9
The sizing agent according to claim 1, which has a ratio of 6:4 to 40:60. 3. Claim 1, wherein the ketene dimer is an alkyl ketene dimer having an alkyl group having 8 to 30 carbon atoms.
Sizing agent as described in section. 4. The sizing agent according to claim 1 or 2, wherein the rosin ester has an acid value of 30 or less and a hydroxyl value of 100 or less.