JPH0114360B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a ketene dimer-based paper sizing agent liquid obtained by dispersing a mixed substance consisting of a ketene dimer and a reaction product of the ketene dimer and an alcohol by adding and stirring an aqueous solution of a water-soluble dispersant. Conventionally, rosin-based sizing agents have been widely used as paper-making sizing agents, but in this case, sulfuric acid is always used as a fixing agent, which causes the papermaking liquid to become acidic during the papermaking process and damage process equipment. There are disadvantages such as In order to avoid this disadvantage, in recent years, attention has been paid to papermaking under neutral or alkaline conditions, and sizing agents using ketene dimers that easily react with cellulose fibers have been developed and used. In the neutral or alkaline papermaking process using this ketene dimer-based sizing agent, the bonds between the constituent fibers of the resulting paper become stronger, which not only improves the paper strength, but also stabilizes the paper strength and shows no change over time. There are also advantages such as less corrosion of equipment during paper making. In addition, calcium carbonate powder or the like can be advantageously used as a filler especially in the papermaking process using a neutral or alkaline system. Due to this, ketene dimer-based sizing agents are useful, but because ketene dimer is a highly reactive substance, the dispersion loses its uniformity during storage, resulting in poor storage stability. The disadvantage is that it lacks. The object of the present invention is to overcome the above-mentioned drawbacks, to maintain a homogeneous dispersion state even after long-term storage, and to possess the above-mentioned excellent properties as a ketene dimer-based paper sizing agent. An object of the present invention is to provide a useful ketene dimer-based sizing agent liquid for paper manufacturing. According to the invention, 97 to 40 parts of ketene dimer;
Reaction product between ketene dimer and alcohol 3~
A sizing agent solution for ketene dimer paper, which is obtained by dispersing the resulting mixture in an aqueous system with an aqueous solution of a water-soluble dispersant, is useful for the purpose of the present invention. This is a sizing agent liquid for use. The ketene dimer-based paper sizing agent liquid of the present invention has excellent storage stability and more This exhibits a size effect. This can be considered to be because the presence of the product of the reaction between the alkyl ketene dimer and the alcohol helps the emulsification and dispersion of the entire system and promotes its stability. The alkyl ketene dimer used in the production of the sizing solution of the present invention has the general structural formula: (In the formula, R ₁ and R ₂ each have 8 carbon atoms.
25 to 25 hydrocarbon groups). Examples of these are octadecyl ketene dimer, hexanedecyl ketene dimer, tetradecyl ketene dimer, dodecyl ketene dimer, and ketene dimer synthesized from natural fatty acid mixtures can also be used. Further, alcohols for producing the sizing solution of the present invention include methanol, ethanol, propyl alcohol, butanol, octanol, decyl alcohol, lauryl alcohol, myristyl alcohol, cetyl alcohol, stearyl alcohol,
Primary alcohols such as oleyl alcohol and benzyl alcohol; isopropyl alcohol, 2-
Ethylhexyl alcohol, 2-butanol, 2
- Secondary alcohols such as pentanol and cyclopentanol; and tertiary alcohols such as t-butyl alcohol. These alcohols can be used alone or in combination of two or more. Further, in the sizing solution of the present invention, ketene dimer is produced in a ratio of 97 to 40 parts, preferably 90 to 60 parts; and a reaction product of ketene dimer and alcohol is produced in a ratio of 3 to 60 parts, preferably 10 to 40 parts. If the amount of the reaction product of the ketene dimer and alcohol in the sizing solution exceeds this range, the sizing effect will decrease, and if it decreases, the storage stability will decrease. In addition, in the production of the sizing agent liquid of the present invention, the reaction between the ketene dimer and the alcohol is 60 to 150
Mainly at 80 to 120℃ for 30 minutes to 10 hours
The mixture of the obtained reaction product and ketene dimer can be dispersed at 40 to 95°C by adding an aqueous dispersant solution; A dispersant or a mixture of a cationic dispersant and a nonionic dispersant can be used. As this cationic dispersant,
For example, those having primary, secondary, and tertiary amino groups, and cationically modified starches having quaternary ammonium groups are suitable, as well as other dicyandiamide formalin resins, polyaminopolyamide resins, urea formalin resins, melamine formalin resins, and dicyandiamide formalin resins. Polyalkylene, polyamine-epichlorohydrin condensate, polyvinylpyridine,
Styrene-dimethylaminoethyl methacrylate copolymers, monomethylamine epichlorohydrin resins, dimethylamine epichlorohydrin resins, and quaternized styrene-dimethylaminoethyl acrylate copolymers can be used. Further, as nonionic dispersants that can be used in combination with this cationic dispersant, polyoxyethylene alkyl ether, polyoxyethylene alkyl phenol ether, sorbitan emulsifiers, etc. can be employed. In the production of the sizing solution of the present invention, 5 to 50%, preferably 10 to 50% of the total weight of the ketene dimer and the reaction product from the ketene dimer and alcohol
An amount of dispersant equivalent to 40% can be used. In addition, the obtained ketene dimer-based sizing agent liquid contains 5 to 30% by weight, preferably 10 to 20% by weight of a hydrophobic dispersion substance composed of ketene dimer and a reaction product of ketene dimer and alcohol.
and the dispersed particle size is 3μ or less. To improve the stability of this ketene dimer-based sizing solution, inorganic acids such as hydrochloric acid, sulfuric acid, nitric acid, and phosphoric acid; organic acids such as formic acid, acetic acid, and chloroacetic acid are added to the sizing agent solution, and its pH is adjusted to 2.5 to 6.0. Preferably 3.0
You can bring it back to ~5.0 and adjust it to make saving more advantageous. The present invention will be explained below using Examples. However, these Examples are not intended to limit the scope of the present invention. All percentages below are by weight. Example 1 Alkyl ketene dimer (hereinafter abbreviated as AKD): A mixed alkyl ketene dimer was obtained by reacting hardened tallow fatty acid chloride in benzene in the presence of triethylamine. When this product was measured by a monomethylamine consumption measurement method which is commonly employed as a method for measuring alkyl ketene dimer purity, the consumption amount was 50 mg/g. AKD and 2-ethylhexyl alcohol reaction product (hereinafter abbreviated as AK-E): 1000 g of the above AKD and 210 g of 2-ethylhexyl alcohol were heated and mixed and reacted at 100°C for 5 hours, resulting in monomethylamine consumption of 0.8 mg/ g reaction product (ester) was obtained. Dispersant: A 10% aqueous solution with a viscosity of 20 cps (25°C) made by steaming cationized starch. The above AKD and ester AK-E in various proportions
The mixture was heated to 70°C and mixed. 80g of this, 200g of the above dispersant (cationic starch) 10% solution, and 550g of water were mixed and heated to 70°C, and predispersed for 5 minutes at the same temperature using a homomixer.
At the same temperature, the mixture was passed through a piston-type high-pressure emulsifier (300 Kg/cm ² ) once for dispersion. Cool immediately and add appropriate amount
10% sulfuric acid was added to adjust the pH to 3.5 to 4.5 (20°C). For comparison, dispersions of AKD and AK-E were each obtained individually in the same manner as above. The non-volatile content and viscosity of these emulsified aqueous dispersions were about 12% and 5 to 30 cps (25 DEG C.), respectively, and the particle sizes were each less than 3 microns. Stability tests were conducted on each of the above aqueous dispersions. The results are shown in Table 1 below.

[Table] However, the above stability test was conducted as follows. 50 g of each aqueous dispersion after preparation was collected in a 100 ml sample bottle, placed in a thermostat at 40°C ± 2°C, taken out every 24 hours, and subjected to vibration to observe the morphology of the aqueous dispersion. As can be seen from Table 1, the ketene dimer-based paper sizing agent liquid according to the present invention has excellent stability. In order to compare the performance of the above six types of aqueous dispersions as sizing agents for paper manufacturing, we used a commercially available ketene dimer sizing agent (non-volatile content 16.1%, PH = 3.8).
A comparative test was conducted using the following method. The method will be described below. That is, a 2% aqueous slurry of 410 ml of Canadian Standard Freeness pulp (LBKP/NBKP=7/3) was added with 20% calcium carbonate powder (based on pulp solid content) as a filler and 0.3% of the above aqueous dispersion (containing non-volatile (% of pulp solids) was added, and then paper was made using a Tatsupi Standard Sheet Machine. The obtained wet paper was dehydrated by pressing at 5 kg/cm ² for 1 minute to give a wet paper moisture content of 60±1%. This was dried for 2 minutes at 80 to 85°C using a rotating drum dryer to obtain paper. This was carried out at 20℃ and 65% for 24 hours.
It was subjected to constant temperature and humidity treatment for hours. The obtained handmade paper has a basis weight of 60
It was ±2 g/m ² . The Steckigt size degree (JIS P8122) of these handmade papers was measured and the results are shown in Table 2.

[Table] This is the percentage that was achieved.
Table 2 shows that the ketene dimer-based paper sizing agent liquid according to the present invention has excellent sizing performance.

Claims (1)

[Claims] 1 97 to 40 parts of an alkyl ketene dimer having an alkyl group having 8 to 25 carbon atoms (hereinafter all "parts" are "parts by weight"), and the above alkyl ketene dimer having an alkyl group having 1 to 30 carbon atoms. A ketene dimer, characterized in that it is obtained by adding and dispersing a mixture of 3 to 60 parts of a reaction product with an alcohol having one hydroxyl group in the molecule, and an aqueous solution of cationized starch. Sizing agent liquid for paper making.