JPH0336958B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a paper sizing composition. More specifically, the present invention relates to a novel ketene dimer-based sizing agent composition that can be used in a neutral or alkaline PH range of papermaking water, has good dispersion stability, and does not require time to develop its sizing effect. Rosin or reinforced rosin (maleated rosin) has been widely used as a sizing agent for paper manufacturing. However, this rosin-based sizing agent requires a fixing step using aluminum sulfate, and therefore has many problems. In other words, fixing with aluminum sulfate has drawbacks such as the fact that the pH of the papermaking water during papermaking is low (acidic), which can cause significant damage to the papermaking machine, impair the printability of the paper, and furthermore, there is a risk of discoloration due to long-term storage of the paper. has been pointed out. Furthermore, when calcium carbonate is used as a material, rosin-based sizing agents cannot be used because calcium carbonate decomposes in acidic solutions. Calcium carbonate is inexpensive and has a high degree of whiteness, so it is known that it is effective when used as a paper filler, but at present its use is extremely limited for the above reasons. Therefore, it has been desired to develop a neutral sizing agent that overcomes the above-mentioned drawbacks and allows the use of calcium carbonate without deteriorating paper quality. In recent years, various neutral sizing agents have been proposed to achieve this purpose, but among them, a sizing agent in which a ketene dimer is colloidally dispersed in water is considered to be the most promising, and has been patented numerous times. has been filed. However, despite these many research efforts, ketene dimer-based sizing agents still have the fatal drawback that it takes time to develop the size effect. In other words, when paper is made using a ketene dimer-based sizing agent, there is almost no size effect immediately after paper making, and it usually takes 2 to 3 days to obtain a sufficient size effect, and in some cases it takes 7 to 10 days. It is said that it takes a lot of time. This problem is generally pointed out as a poor rise in the size effect, but it is easy to imagine that this poor rise leads to the following drawbacks. That is, it is difficult to control the quality of paper that requires a high size effect in the final product, such as writing paper or milk cartons. Furthermore, in order to obtain a high size effect, the paper must be shipped after several days have elapsed, but it goes without saying that storage until shipping increases the cost of paper. On the other hand, in the case of coated paper, an internal sizing agent is used to control the amount of liquid absorbed during the coating process. Currently, coating is often carried out continuously from paper making, and in this case, it is completely useless if the size effect does not appear immediately after the wet paper is dried (immediately after paper making). Although ketene dimer-based sizing agents have excellent performance, such as being able to be used in the neutral region, producing sizing effects with low addition amounts, and producing high-size paper, their use is extremely difficult due to the reasons mentioned above. The current situation is that it is restricted. In view of the above circumstances, the present inventors have conducted extensive research into improving the rise of ketene dimer-based sizing agents, and have surprisingly found that they contain one or more types of linear saturated fatty acids having 16 to 24 carbon atoms. We have found that a ketene dimer produced from a straight chain saturated fatty acid mixture in which the maximum content of fatty acids is 80% or more is effective in improving the rise. However, a sizing agent composition in which the ketene dimer is colloidally dispersed in water has a drawback of significantly poorer dispersion stability than conventionally used ketene dimers. This dispersion stability is improved by lowering the concentration of ketene dimer in the sizing composition. However, the conventional ketene dimer-based sizing agent compositions currently on the market have an active ingredient content of 6 to 12% by weight, and products with lower active ingredients than this require high costs for transportation, filling, etc. Furthermore, a large-capacity container is required for storage, which is extremely uneconomical. The present inventors have conducted further intensive research into dispersion stabilization of the ketene dimer at an effective ingredient concentration equivalent to or higher than that of conventional ketene dimer-based sizing agent compositions, and have found that, unexpectedly, The present inventors have discovered that this objective can be achieved by blending a specific modified starch as a dispersant in water with the ketene dimer, and have completed the present invention. That is, the present invention is a paper sizing agent composition comprising an aqueous dispersion containing the following compounds () and (). () Contains one or more types of straight chain saturated fatty acids, and the number of carbon atoms of the fatty acid with the maximum content is
16-24 and produced from a straight-chain saturated fatty acid mixture containing 80% by weight or more of ketene dimer (). 0.02-0.1 cationic groups and 0.05-0.2 cationic groups per anhydroglucose unit. carbon number 2-4
To obtain the above-mentioned ketene dimer constituting the present invention, for example, a modified starch having a 2-hydroxyalkyl group of A known method may be applied in which a raw fatty acid mixture is converted into a fatty acid chloride and then a dehydrochlorination reaction is carried out in the presence of a tertiary amine catalyst. Processed starch, which is another component of the present invention, is obtained by introducing a cationic group and a 2-hydroxyalkyl group into raw starch, and then cutting the starch main chain to reduce the molecular weight. Here, after cutting the starch main chain, a cationic group and a 2-hydroxyalkyl group may be introduced. At this time, the reaction conditions were such that the modified starch had 0.02 to 0.1 cationic groups and 0.05 to 0.2 2-hydroxyalkyl groups per anhydroglucose unit. It is necessary to set conditions for cutting and reducing the molecular weight so as to have a viscosity of ~25 centipoise, and specific examples thereof will be shown in the production examples. As the raw starch, corn starch, potato starch, tapioca starch, wheat starch, and seed powder or rhizome powder containing these starches can be used. In the presence of an alkali substance such as an alkali metal or alkaline earth metal hydroxide or quaternary ammonium hydroxide, the cationic group can be converted into 2-diethylaminoethyl chloride, 3-diethylamino-
It can be introduced by reacting starch with a cationizing reagent such as 1,2-epoxypropane, 3-dibutylamino-1,2-epoxypropane, 2-chloroethyltrimethylammonium chloride, or glycidyltrimethylammonium chloride. The 2-hydroxyalkyl group can be introduced by reacting an alkylene oxide having 2 to 4 carbon atoms, such as ethylene oxide, propylene oxide, or isobutylene oxide, with starch in the presence of the alkali substance. The above-mentioned cationic group introduction reaction and 2-hydroxyalkyl group introduction reaction can be carried out by suspending starch in an aqueous sodium sulfate solution, a water-isopropanol mixed solvent, or a water-methanol mixed solvent, or by suspending starch in a water-isopropanol mixed solvent. It can also be done by gelatinizing. The molecular weight of starch is reduced by oxidatively using sodium hypochlorite or hydrogen peroxide, or by cutting the starch main chain during hydrolysis with mineral acids such as hydrochloric acid, nitric acid, or sulfuric acid. be able to. The specification of the degree of substitution of cationic groups and 2-hydroxyalkyl groups (meaning the number of cationic groups and 2-hydroxyalkyl groups per anhydroglucose unit) and the specification of the aqueous solution viscosity of the processed starch are essential requirements of the present invention. It is. That is, modified starch in which the degree of substitution of cationic groups is less than 0.02 and more than 0.1,
Modified starches with a degree of substitution of 2-hydroxyalkyl groups of less than 0.05 and more than 0.2, and modified starches with a viscosity of 8% by weight aqueous solution of less than 3 centipoise and more than 25 centipoise at 30°C, are all suitable for the present invention. It is not possible to achieve dispersion stabilization. To obtain the sizing agent composition of the present invention, for example, firstly, processed starch is poured into water and dissolved by heating, and then a ketene dimer is added to this aqueous solution, and the ketene dimer is dissolved in a state in which the ketene dimer is dissolved. Mix and disperse. The ketene dimer may be added as a solid to the aqueous solution, or may be melted beforehand and added. The temperature when mixing and dispersing the ketene dimer in the aqueous solution is higher than the melting point of the ketene dimer and lower than 100°C, preferably lower than 80°C. If the temperature is too high, the ketene dimer may react with water, producing compounds without size effects. The composition ratio of each component of the sizing agent composition of the present invention is preferably 5 to 20% by weight for the ketene dimer. If it exceeds 20% by weight, the dispersion stability will be insufficient, and if it is less than 5%, it will be difficult to transport as mentioned above.
This is because filling costs and the like become expensive. On the other hand, modified starch is 20-100% by weight based on ketene dimer.
is preferred. If it exceeds 100% by weight, the viscosity of the composition becomes high and difficult to handle;
This is because if it is less than this, the ketene dimer will not be sufficiently dispersed. Next, regarding the size of the sizing agent particles, it is desirable that the particle size of the sizing agent particles dispersed in water be 5 microns or less, preferably 2 microns or less. If the particle size is larger than 5 microns, the stability of the dispersion may be impaired or the size effect may be poor. A homomixer, an ultrasonic emulsifier, a high-pressure discharge type homogenizer, etc. can be used to disperse the particles. In order to use the sizing agent of the present invention with good yield, it is effective to use a fixing agent, and a cationic polymer is preferable as the fixing agent. Preferred examples of cationic polymers used as fixing agents include cationized starch, cationized cellulose, polyamide polymers, polyethyleneimine, polyvinylpyridine and its quaternized products, polydimethylaminoethyl methacrylate and its quaternized products, and polyester. Examples include diethylaminoethyl methacrylate, quaternized products thereof, and copolymers of these cationic monomers and acrylamide. In carrying out the present invention, the sizing composition of the present invention is added in an amount of 0.01 to 2% by weight, preferably 0.05 to 1% by weight, as a solid content based on the weight of the pulp. It goes without saying that the level of addition of these sizing agents is adjusted depending on the degree of sizing required by the target paper. The present invention will be explained below using production examples and examples, but the present invention is not limited to these production examples and examples. Note that parts in the examples are based on weight. Production examples and comparative production examples of processed starch Production example 1 Dissolve 2.2 parts of sodium hydroxide and 50 parts of sodium sulfate in 125 parts of water and immediately add 100 parts of corn starch. Next, 5 parts of diethylaminoethyl chloride are added, and after stirring at 45°C for 5 hours, the temperature is lowered to 40°C, 8 parts of propylene oxide are added, and the mixture is stirred at 40°C for 8 hours. Furthermore, 18 parts of 35% hydrogen peroxide solution was added and stirred for 4 hours. Thereafter, dilute hydrochloric acid is added to lower the pH to 4.5, and the reaction product is separated by filtration, washed with water, and dried. The obtained processed starch has a degree of diethylaminoethyl substitution.
0.05, the degree of hydroxypropyl group substitution was 0.10, and the viscosity was 10 centipoise at 30°C as an 8% by weight aqueous solution. Production Example 2 A mixed solution consisting of 8 parts of water, 8.2 parts of methanol, and 50% aqueous sodium hydroxide solution is added to 100 parts of cornstarch to disperse the cornstarch. After dispersion, add 10 parts of ethylene oxide and stir at 38°C for 10 hours. Next, the reactant was poured into 120 parts of water, the temperature was raised to 43°C, 4 parts of diethylaminoethyl chloride was added, and a 3% aqueous sodium hydroxide solution was added, and the mixture was stirred for 5 hours while maintaining the pH at 11. . Furthermore, reduce the temperature to below 30℃ and add 40 parts of sodium hypochlorite containing 14% available chlorine.
Stir for an hour. Then, add dilute hydrochloric acid to adjust the pH.
4.5, and the reaction product was separated by filtration.
Wash with water and dry. The obtained processed starch has a degree of diethylaminoethyl group substitution of 0.04, a degree of hydroxylethyl substitution of 0.14, and a viscosity of 8% by weight aqueous solution.
It was 12 centipoise in °C. Production Example 3 Dissolve 1.8 parts of sodium hydroxide and 50 parts of sodium sulfate in 125 parts of water, and add 100 parts of potato starch. Next, add 8 parts of butylene oxide,
Stir at 40°C for 8 hours. Next, the temperature was raised to 43°C, 4 parts of dimethylaminoethyl chloride was added, and the mixture was stirred for 5 hours. Furthermore, dilute hydrochloric acid was added to lower the pH to 5, 18 parts of 20% hydrochloric acid was added, and the mixture was stirred at 40°C for 15 hours. Thereafter, a 3% aqueous sodium hydroxide solution is added to adjust the pH to 4.5, and the reaction product is separated by filtration, washed with water, and dried. The obtained processed starch has a dimethylaminoethyl group substitution degree of 0.04,
The degree of substitution with bidroxybutyl group was 0.09, and the viscosity was 8 centipoise at 30°C as an 8% by weight aqueous solution. Production Example 4 Diethylaminoethyl chloride 5 of Production Example 1
Processed starch was produced in the same manner as in Production Example 1, except that 6 parts of 2-chloroethyltrimethylammonium chloride was used. The obtained processed starch has an ammonium group substitution degree of 0.05, a hydroxypropyl group substitution degree of 0.09, and a viscosity of 8% by weight aqueous solution.
It was 11 centipoise in °C. Comparative Production Example 1 A processed starch was produced in the same manner as in Production Example 1, except that the amount of diethylaminoethyl chloride added was 1 part. The obtained processed starch had a degree of diethylaminoethyl group substitution of 0.01, a degree of hydroxypropyl group substitution of 0.10, and a viscosity of 10 centipoise at 30° C. as an 8% by weight aqueous solution. Comparative Production Example 2 Dissolve 5.2 parts of sodium hydroxide and 50 parts of sodium sulfate in 125 parts of water, and immediately add 100 parts of corn starch. Next, 12 parts of diethylaminoethyl chloride were added, and after stirring at 40°C for 8 hours, the temperature was lowered to 30°C, 8 parts of propylene oxide was added, and the mixture was stirred at 30°C for 24 hours. Furthermore, 18 parts of 35% hydrogen peroxide solution was added and stirred for 4 hours. Thereafter, dilute hydrochloric acid is added to lower the pH to 4.5, and the reaction product is separated by filtration, washed with water, and dried. The obtained processed starch has a degree of diethylaminoethyl group substitution.
0.11, the degree of hydroxypropyl group substitution was 0.10, and the viscosity was 12 centipoise at 30°C as an 8% by weight aqueous solution. Comparative Production Example 3 A processed starch was produced in the same manner as in Production Example 1 except that the amount of propylene oxide added was changed to 3 parts. The obtained processed starch has a degree of diethylaminoethyl substitution of 0.01, a degree of hydroxypropyl group substitution of 0.04, and a viscosity of 9% by weight at 30°C in an 8% aqueous solution.
It was centipoise hot. Comparative Production Example 4 Dissolve 2.2 parts of sodium hydroxide and 50 parts of sodium sulfate in 125 parts of water, and immediately add 100 parts of corn starch. Next, 5 parts of diethylaminoethyl chloride were added, and the mixture was stirred at 45°C for 5 hours, then the temperature was lowered to 30°C, 20 parts of propylene oxide was added, and the mixture was stirred at 30°C for 24 hours. Furthermore, 18 parts of 35% hydrogen peroxide solution was added and stirred for 4 hours. Thereafter, dilute hydrochloric acid was added to lower the pH to 4.5, and the reaction product was separated by filtration, washed with water, and dried. The obtained processed starch has a degree of diethylaminoethyl group substitution.
0.05, the degree of hydroxypropyl group substitution was 0.23, and the viscosity was 10 centipoise at 30°C as an 8% by weight aqueous solution. Comparative Production Example 5 Processed starch was produced in the same manner as in Example 1, except that the stirring time after adding the hydrogen peroxide solution in Production Example 1 was changed to 2 hours. The obtained processed starch has a diethylaminoethyl group substitution degree of 0.05, a hydroxypropyl group substitution degree of 0.10, and a viscosity of 8% by weight aqueous solution.
It was 31 centipoise in °C. Comparative Production Example 6 A modified starch was produced in the same manner as in Production Example 1, except that the stirring time after adding the hydrogen peroxide solution was changed to 16 hours. The obtained processed starch has a diethylaminoethyl group substitution degree of 0.05, a hydroxypropyl group substitution degree of 0.10, and a viscosity of 8% by weight aqueous solution.
It was 2.5 centipoise in °C. Examples 1 to 6 and Comparative Examples 1 to 8 After heating and dissolving the processed starches produced in Production Examples 1 to 4 and Comparative Production Examples 1 to 6 in water, a ketene diacetate having the raw fatty acid composition shown in Table 1 was added. add mass
Melt at 70℃ and pressurize with a high-pressure discharge homogenizer.
It was emulsified at 200 kg/cm ² and further cooled to obtain a sizing agent composition. The composition of the obtained sizing agent composition is shown in Table 2.

【table】

[Table] <Stability test> The dispersion stability test of the sizing agent composition was conducted after the sizing agent composition shown in Table 2 was left at temperatures of 5°C, 20°C, and 40°C for one month. The dispersion state of the sizing agent was visually observed. The results are shown in Table 3. The meanings of the symbols shown in Table 3 are as follows. ○: The emulsified state is almost the same as the initial state. Δ: The emulsion has slightly thickened, but can be used. ×: The emulsion was significantly thickened or gelatinized and could not be used. Alternatively, it is unusable due to creaming.

[Table] As is clear from Table 3, the sizing agent compositions of Examples 1 to 6 according to the present invention exhibit good dispersion stability, but when the modified starches produced in Comparative Production Examples 1 to 6 were used ( This corresponds to Comparative Examples 1 to 6) is 20
Dispersion stability at ℃ and 40℃ is poor. <Size Test> The paper used in this test was manufactured under the following conditions. Pulp: LBKP (CS Freeness 410ml) Amount of sizing agent added: Solids content relative to pulp weight 0.2
Weight % Stabilizer: Polyalkylene polyamide cationic polymer (commercial product) Solid content relative to pulp weight
0.2% Fixation PH: 7.0 Papermaking: Tatsupi square hand paper machine Press: 3.5Kgω/cm ² x 3 minutes Drying: Rotary dryer, 95℃ x 25 seconds Basis weight: 60g/m ³ Size degree test is next I did it using the method shown. Sizing test: Stekicht method (JISP-8122) Fold the four sides of the test paper upwards to make a boat shape, and add 2%
Float on NH ₄ SCN aqueous solution. At the same time as floating, a drop of a 1% FeCl ₃ aqueous solution was dropped onto the test paper from above, and the time (seconds) until both aqueous solutions penetrated the paper and came into contact with it, and three red spots of iron thiocyanate appeared, was measured. The sizing of the paper made under the above conditions was measured immediately after the paper was made, 1 hour later, and 1 day later. The test results are shown in Table 4.

【table】

Claims (1)

[Scope of Claims] 1 () Straight-chain saturated fatty acids containing one or more types of straight-chain saturated fatty acids, in which the maximum content of the fatty acid has 16 to 24 carbon atoms, and which contains 80% by weight or more of straight-chain saturated fatty acids. A ketene dimer produced from a mixture of chain saturated fatty acids, and () having 0.02 to 0.1 cationic groups and 0.05 to 0.2 2-hydroxyalkyl groups having 2 to 4 carbon atoms per anhydroglucose unit. A paper sizing agent composition comprising an aqueous dispersion containing 8% by weight of modified starch having a Bruckfield viscosity of 3 to 25 centipoise at 30°C.