JPS6014159B2 - paper sizing agent - Google Patents

Description

[Detailed description of the invention] The present invention relates to a novel paper sizing agent.

More specifically, it uses a 1-(substituted carbonyl) imidazole transferor as an active ingredient, does not require a fixing agent such as sulfuric acid, and exhibits good sizing effects even when papermaking water is in the neutral to alkaline pH range. This invention relates to paper sizing agents. Most paper is made by adding paper sizing agents (hereinafter referred to as sizing agents), but since the resulting paper needs to have water resistance and ink bleed resistance, rosin is generally used. Anionic sizing agents are widely used as excellent sizing agents.

However, in paper making using rosin-based sizing agents, it is necessary to fix the sizing agent to the pulp using a sulfuric acid band and then make it hydrophobic, so there is a constraint that the pH of the system must be maintained in the acidic range during paper making. There is. On the other hand, many papers require papermaking in a neutral range from the standpoint of usage and processability, and acidic aluminum compounds such as sulfuric acid cannot be used in such processes. Therefore, rosin-based sizing agents cannot exhibit excellent effects as sizing agents. Also, the opacity of paper,
Clay, talc,
There are many 'meh' products that contain fillers such as titanium oxide. In addition, calcium carbonate is often used for fillers that require basic fillers, or for fillers that use cheaper fillers instead of clay, talc, titanium oxide, etc., so it is difficult to make paper in an acidic region. , calcium carbonate decomposes and generates carbon dioxide gas, which interferes with paper making. Therefore, the powder using calcium carbonate as a filler is neutral ~
Since sizing must be carried out in an alkaline region, rosin-based sizing agents cannot be used, and a sizing agent capable of neutral sizing is desired. In view of the current situation, the present inventors have conducted extensive research and found that when using a 1-(substituted carbonyl) imidazole derivative as a sizing agent, it exhibits an extremely excellent sizing effect in the neutral pH region. and the 1-(substituted carbonyl)
We have discovered that an aqueous emulsion obtained by emulsifying an imidazole derivative in water can be used for a long period of time after its preparation, but still exhibits the same excellent size effect as immediately after preparation, and has completed the present invention. I arrived. That is, the present invention provides a solution to the general formula (where RI is a hydrogen atom, a phenyl group, or an alkyl group having 1 to 20 carbon atoms, and R2 and R3
is a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, or R2 and R3 are bonded together to form a benzene ring together with the carbon atoms of the imidazole ring to which they are bonded.

A is a hydrophobic group having 8 to 4 carbon atoms. The sizing agent of the present invention is a so-called reactive sizing agent that reacts with the pulp to make the pulp hydrophobic even when sulfuric acid bands are not present.

That is, the sizing agent of the present invention contains 1 as its active ingredient.
The carbonyl group activated by the imidazyl group of the mono(substituted carbonyl)imidazole derivative reacts with the hydroxyl group of the pulp during heat drying, imparting hydrophobicity to the pulp and imparting excellent water resistance to paper. The fact that the reactivity with the hydroxyl groups of the pulp is high means that the reactivity with the water present around the sizing agent is also high. There are several conventionally known reactive sizing agents, but many of these react with water and denature during storage as an aqueous emulsion, resulting in a decrease in sizing effect over time. In some cases, the aqueous emulsion becomes unusable after just one day of preparation. However, when the 1-(substituted carbonyl)imidazole derivative used in the present invention is made into an aqueous emulsion for a long period of time at room temperature, at least 1-(substituted carbonyl)imidazole derivative
It is stable for several months, and even when used as a sizing agent after a long period of time, it exhibits the same excellent sizing effect as a sizing agent used immediately after preparation.

The 1-(substituted carbonyl) imidazole derivative, which is the active ingredient of the sizing agent of the present invention, is produced by the reaction of imidazoles with carboxyl chloride, carbamate chloride, chloroformate, chloroformate thioester, isocyanate ester, etc. .

In the present invention, as the imidazole, it is preferable to use imidazole itself or its lower alkyl substituted product (excluding 1-substituted product).

Examples of lower alkyl substituents of imidazole include 2-methylimidazole, 4-methylimidazole, 5-methylimidazole, 2,4-dimethylimidazole, 2-ethylimidazole, 4-ethylimidazole, 2-ethyl-4-methylimidazole, Examples include 2-ethyl-5-methylimidazole, 2-isopropylimidazole, and 4-propylimidazole.
In addition to these, in the present invention, for example, 2-butylimidazole, 2-hexylimidazole, 2-hebutylimidazole, 2-/nylimidazole, 2-undecylimidazole, 2-undecyl-4-methylimidazole, 2-cyclohexylimidazole, Bivalent phenylimidazole, 2-phenyl-4-methylimidazole, benzimidazole, and the like can also be used. On the other hand, carboxylic acid chloride, carbamic acid chloride, chloroformate ester, chloroformate thioester, isocyanate ester, etc. each have the general formula R4COC1
, R5R6NCOC1, R70COC1, R8SCOC
1, denoted by R9NCO.

R thousand, R5, R7, R8 and R9 have 8 to 30 carbon atoms
hydrocarbon groups, such as octyl, nonyl, detosyl, undedocyl, dode'
sil, tridecyl, tetradecyl, bentadecyl, hexadecyl, heptadecyl, octadecyl, eicosyl,
Alkyl groups such as docosyl and tetracosyl; alkenyl groups such as octenyl, nonenyl, decenyl, dodecenyl, tridecenyl, bentadecenyl, octadecenyl, and tricosenyl; 4-t-butylphenyl, octylphenyl, nonylphenyl, dodecylphenyl, tridecylphenyl, pentade Examples include alkaryl groups such as sylphenyl and octadecyl phenyl; cycloalkyl groups such as nonylcyclopropyl, dodecylcyclobutyl, and hexylcyclohexyl; aralkyl groups such as p-nonylphenyl ethyl; 12 to 20 hydrocarbon groups are preferred. R6 is a hydrogen atom, a methyl group, an ethyl group, a propyl group, a butyl group, a bentyl group, a hexyl group, a heptyl group, or a phenyl group, as well as a hydrocarbon group having 8 to 8 carbon atoms among the hydrocarbon groups represented by R5.
20 items. However, it is appropriate to select so that the total carbon number of each of the hydrocarbon groups represented by R5 and R6 does not exceed 40. The reaction of the imidazoles with carboxylic acid chloride, carbamic acid chloride, chloroformic acid ester or chloroformic acid thioester,
Triethylamine, N-methylmorpholine, pyridine,
-20 to 1100, preferably 0 to 30 in the presence of a dehydrochlorinating agent such as sodium carbonate or magnesium oxide
The process is carried out at a temperature of 10 minutes to 5 hours. The reaction can be carried out in an inert organic solvent such as ether, benzene, toluene, ethyl acetate, chloroform, tetrahydrofuran, or in water. The ratio of imidazoles and other reaction components used may be approximately equimolar. After the reaction is complete,
The reaction solvent, raw salt, unreacted substances, etc. are removed by distillation or filtration to obtain a reaction product. When the reaction product is solid, it is purified by recrystallization using hexane, benzene, ethyl acetate, tetrahydrofuran, etc. In addition, the reaction between imidazoles and isocyanate esters is
0-150oo under anhydrous conditions, preferably 30-100oo
The process is carried out under water for 10 to 5 hours at a temperature of q0.

The reaction is preferably carried out in the inert solvents mentioned above.
The ratio of imidazoles and isocyanate ester used may be approximately equimolar. The treatment after the completion of the reaction may be carried out in the same manner as described above. The 1-(substituted carbonyl)imidazole derivative can also be obtained by a method utilizing a decarboxylation reaction between a dimidazyl ketone and a carboxylic acid or a substitution reaction between a dimidazyl ketone and a primary or secondary amine.

These reactions are carried out at a temperature of -20 to 1100°C, preferably in the above-mentioned inert organic solvent, for 1 minute to 5 hours. Specific examples of the 1-(substituted carbonyl)imidazole derivatives thus obtained and used in the present invention include 1-lauroyimidazole, 1-lauroy-2-methylimidazole, 1-lauroy-4-methylimidazole, and 1-lauroy-imidazole. 2-ethyl-4-methylimidazole, 1
- myristoylimidazole, 1-myristoyl-2-methylimidazole, 1-myristoyl-4-methylimidazole, 1-/glumitoylimidazole, 1-stearoylimidazole, 1-stearoyl-2-methylimidazole, 1-stearoyl-2-isof.

Propylimidazole, 1-stearoyl-4-methylimidazole, 1-stearoyl-2-ethyl-4-methylimidazole, 1-oleoylimidazole, 1-oleoyl-2-ethyl-4-methylimidazole, 1
- Imidazole derivatives in which A in the above general formula is a hydrocarbon group, such as stearoylbenzimidazole, 1-(p-nonylphenylcarbonyl)imidazole, 1-(p-nonylphenylethylcarbonyl)imidazole; 1-(laurylcarbamoyl) ) imidazole, 1-
(laurylcarbamoyl)-2-methylimidazole,
1-(tridecylcarbamoyl)imidazole, 1-(
myristylcarbamoyl) imidazole, 11(myristylcarbamoyl)14-methylimidazole, 11(
Bentadecylcarbamoyl)imidazole, 1-(palmitylcarbamoyl)imidazole, 1-(palmitylcarbamoyl)-2-isopropylimidazole, 1-
(Heptadecylcarbamoyl)imidazole, 1-(stearylcarbamoyl)imidazole, 1-(stearylcarbamoyl)-2-methylimidazole, 1-(stearylcarbamoyl)-4-methylimidazole, 1
-(stearylcarbamoyl)-2-isopropylimidazole, 1-(stearylcarbamoyl)-12-phenylimidazole, 1-(stearylcarbamoyl)-2-ethyl-4-methylimidazole, 1-(oleylcarbamoyl)imidazole, 1-(stearylcarbamoyl)-2-ethyl-4-methylimidazole, (oleylcarbamoyl)-4-methylimidazole, 1-(stearylcarbamoyl)penzimidazole, 1-(p-nonylphenylcarbamoyl)imidazole, 1-(p-nonylphenylethylcarbamoyl)imidazole, 1-(N
-Methyl-4N-stearylcarbamoyl)imidazole, 1-(N-dodecyl-N-octylcarbamoyl)
Imidazole derivatives in which A in the above general formula is a substituted amino group, such as imidazole, 1-(N·N-distearylcarbamoyl)imidazole, and 1-(N·N-dioleylcarbamoyl)imidazole; 1 -(lauroxycarbonyl)imidazole, 1-(lauroxycarbonyl)-2-methylimidazole, 1-(myristoxycarbonyl)imidazole, 1-(myristoxycarbonyl)-2-ethyl-4-methylimidazole, 1 -(palmitoxycarbonyl)imidazole, 1-(palmitoxycarbonyl)-2-isopropylimidazole,
1-(stearoxycarbonyl)imidazole, 1-(
stearoxycarbonyl)-4-methylimidazole,
1-(oleoxycarbonyl)imidazole, 1-(p
-nonylphenyloxycarponyl)imidazole, 1
Imidazole derivatives in which A in the above general formula is a substituted oxy group, such as 1-(p-nonylphenylethyloxycarbonyl)imidazole; 1-(laurylthiocarbonyl)imidazole, 1-(myristylthiocarbonyl)
Imidazole, 1-(stearylthiocarbonyl)imidazole, 1-(palmitylthiocarbonyl)imidazole, 1-(p-nonylphenylthiocarbonyl)imidazole, 1-(p-nonylphenylethiocarbonyl)imidazole, etc. It will be done. The sizing agent of the present invention contains the above-mentioned 1-(substituted carbonyl)imidazole derivative as an active ingredient, and exhibits particularly excellent effects as a so-called internal sizing agent added to pulp slurry during paper making. The 1-(substituted carbonyl) imidazole derivative can be added to the pulp slurry as it is in the form of a fine powder, but it is better to emulsify it in water with an emulsifier to make an aqueous emulsion and then add it to the pulp slurry. is preferred.

In this case, anionic, nonionic or cationic emulsifiers can be used as the hair protection agent, but in particular polyoxyethylene alkyl ether, polyoxyethylene alkyl phenylene ether, polyoxyethylene polyoxypropylene block polymer, Polyoxyethylene sorbitan fatty acid ester, polyoxyethylene glycerin fatty acid ester, polyoxyethylene aliphatic amine t
Nonionic surfactants such as fatty acid monoglycerides, sorbitan fatty acid esters, bentaerythritol fatty acid esters, propylene glycol fatty acid esters, sucrose fatty acid esters, polyglycerol fatty acid esters, fatty acid alkanolamides, amine oxides; tetraalkylammonium salts, Cationic surfactants such as alkylbenzylammonium salts and alkylimidazo 1'nium salts; cationic starches such as primary, secondary, tertiary or quaternary amiso-modified starches; cationic modified urea-formaldehyde resins; Cationic urea melamine resin, polyacrylamide cationically modified by Mannich reaction, Hofmann rearrangement reaction, or deammonization condensation reaction with polyethyleneimine, or copolymer of acrylamide and other vinyl monomers, polyamide polyamine resin , polyamide polyamine polyester polyether resin, polyethyleneimine, polymers of cationic monomers such as N●N-dialkylaminoalkyl (meth)acrylate or copolymers of these with other vinyl monomers, cyclobentadiene and Various average molecular weights such as thermal copolymers with cationic monomers such as allylamine, and those obtained by modifying the above cationic polymers with epichlorohydrin or quaternizing them with alkyl halides, etc.
Water-soluble cationic polymeric protective colloid with a molecular weight of 1,000 or more; It is preferable to use a water-lacquered nonionic polymeric protective colloid with an average molecular weight of 1,000 or more, such as polyvinyl alcohol, polyacrylamide, starch and its derivatives, and these may be used alone. used in or in combination. It is particularly preferred to use nonionic surfactants and water-soluble cationic polymeric protective colloids. The amount of the emulsifier used is 0.5 to 20% (wt%) of the surfactant relative to the 1-(substituted carbonyl)imidazole derivative.
, hereinafter the same), preferably from 1 to 10%, and the ratio of the water-soluble polymer protective colloid is from 10 to 300%, preferably from 20 to 250%.

As mentioned above, the sizing agent of the present invention contains the 1-(substituted carbonyl)imidazole derivative as an essential component, but waxes may be used in combination as necessary.

Particularly in applications where the melting point of the 1-(substituted carponyl)imidazole derivative exceeds 80°C, it is preferable to use a wax in combination, since this lowers the melting point of the resulting mixture and facilitates emulsification of the mixture. Examples of such waxes include mineral waxes such as polyethylene wax, polypropylene wax, paraffin wax, and microcrystalline wax, as well as animal waxes and vegetable waxes, and have a melting point of 10,000 or less, especially 40 to 80°C are preferably used. The amount of wax used is preferably in the range of 10 to 100%, especially 20 to 50%, based on the 1-(substituted carbonyl)imidazole derivative. In addition, when waxes are used in combination, the amount of the emulsifier used may be increased in accordance with the amount of waxes used. The emulsification method may be a conventionally known method, in which the 1-(substituted carbonyl)imidazole derivative or a mixture of it and waxes is added to an aqueous solution containing an emulsifier, and an emulsifying machine such as a kneader, homomixer,
Emulsify using a high-speed homogenizer, high-pressure emulsifier, etc.

When emulsifying, the total solids concentration should be 1 to 40%.
The treatment may be carried out at a temperature of 20 to 10,000 for several minutes to 30 minutes. Alternatively, a 1-(substituted carbonyl)imidazole derivative or a mixture of this and a wax may be dissolved in a hydrophobic organic solvent such as benzene, toluene, cyclohexane, or carbon tetrachloride to form a solution, and then emulsified according to a conventional method. Good too. Although an aqueous emulsion obtained using a hydrophobic organic solvent can be used as a sizing agent as it is, it is preferable to remove the organic solvent by distillation under reduced pressure after emulsification. An aqueous emulsion of the 1-(substituted carbonyl)imidazole derivative is thus obtained,
The particle size is usually less than 2 French. When using the sizing agent of the present invention, conventional neutral sizing methods can be applied as is.

The strength of an aqueous emulsion obtained using a surfactant or a water-soluble nonionic polymeric protective colloid is
In order to fix the emulsion to the pulp, it may be added to the pulp slurry together with the water-soluble cationic polymer protective colloid described above, and the amount of the aqueous emulsion and water-soluble cationic polymer protective colloid to be used in this case is based on the dry weight of the pulp. 0.05 to 3% each in terms of solid content
and in the range of 0.01 to 1%. On the other hand, for the aqueous emulsion obtained using a water-soluble cationic polymer protective colloid, it can be added as it is to the pulp slurry, and the amount used is 1 - The content of the (substituted carbonyl)imidazole derivative or a mixture thereof with waxes is in the range of 0.05 to 3%. Paring using the sizing agent of the present invention,
, paper chemicals such as sizing agents, dyes, paper strength agents, fixing aids, etc. can be used together, and the order of addition of these and sizing agents can be arbitrary, and the pH range in which paper can be made is from acidic to alkaline. Widely used in clay, talc,
Various fillers such as titanium oxide and calcium carbonate can be used. The sizing agent of the present invention can also be used as a surface sizing agent. In order to use the surface sizing agent, the aqueous emulsion described above is sprayed onto pre-formed wet paper, or an organic solvent solution of a 1-(substituted carbonyl) imidazole derivative is sprayed onto dry paper, diluted, It may be applied by conventional methods such as painting. Next, the sizing agent of the present invention will be explained with reference to Examples. Reference Example 1 In a 4-hour flask equipped with a flywheel, reflux condenser, dropping funnel, and thermometer, 50% of ether, imidazole (
3.4 hours of reagent grade 1) and 6 hours of triethylamine were added and dissolved by candlelight.

Then, a solution prepared by dissolving 15.2 mm of stearic acid chloride (1st grade reagent) in 50 mm of ether was added dropwise in portions while maintaining the temperature of the reaction system at 15 to 20 CO. After the dropping was completed, the cassava was further heated at 20 to 2,500 ml for 1 hour.
After the reaction was completed, the triethylamine hydrochloride produced by Tomiyama was separated in a furnace, and the ether was distilled off from the furnace liquid to obtain a pale yellow powder of 16 mm. This powder was then recrystallized from benzene to yield 1-stearoylimidazole in the form of colorless needles. The melting point of this product is 84.5-85.5qo, and the infrared absorption spectrum is -1 of 1735c (C=○), 3100c
There were 3 (N=CH) in ~3150 arc-1. Reference Example 2 A reaction product of 14.6 mm was obtained in the same manner as in Reference Example 1, except that 13.8 mm of palmitic acid chloride was used in place of stearic acid chloride, and a petroleum ether-benzene mixture [mixing ratio (weight ratio)] ) 1:1], colorless needle-like crystals of 1-palmitylimidazole were obtained by recrystallization.

The melting point of this thing is 82.5~I. It was ○. Reference example
3.Produced 1 in the same manner as Reference Example 1 except that myristic acid chloride 12.4 times was used instead of stearic acid chloride.
- Myristoylimidazole took 12.9 hours.

The melting point of this product was 77 to 78.5 qo. Reference Example 4 15.5 times of 1-oleoyl imidazole was obtained in the same manner as in Reference Example 1, except that 15.1 times of oleic acid chloride was used in place of stearic acid chloride.

This product was 25o0 in the form of a pale yellow paste. Reference Example 5 A reaction product of 17.4 mm was obtained in the same manner as in Reference Example 1, except that 16.6 mm of stearyl chloroformate was used in place of stearic acid chloride, and colorless needles were obtained by recrystallization from a petroleum enamel-penzene mixture. A crystalline form of 1-(stearyloxycarbonyl)imidazole was obtained.

The melting point of this product was 72.5-73.500. Reference Example 6 A flask similar to Reference Example 1 was charged with 100 g of benzene and 6.8 g of imidazole, and heated to melt the fly trunks under reflux of benzene.

Then, a solution prepared by dissolving 29.5 m of stearyl isocyanate in 50 m of benzene was added dropwise over a period of 15 minutes at the reflux temperature of benzene. After further cooling at the same temperature for 1 hour, benzene was distilled off under reduced pressure. Petroleum ether 1 when hot
00' was added and the resulting slurry was filtered to yield 32.5 liters of white powder. This powder was recrystallized from benzene to obtain 1-(stearylcarbamoyl)imidazole. The melting point of this product is 78.5o○ to 79.5o0, and the infrared absorption spectrum is 1710 arc-1 (C=.)
, 3400 arc-1 (shiNH), 1550 enemy-1 (6N
-H), 3100 to 3150 Ka-1 (C=NH
)Met. Elemental analysis value: C22nd 4, theoretical value (%) as ON3: C72.66HII. 38NIl. 56
Actual value (%): C72.55HII. 51NIl. 42
Reference Example 7 34.9 days of 1-(stearylcarbamoyl)-2-methylimidazole was obtained in the same manner as in Reference Example 5, except that 8.2 hours of 2-methylimidazole was used in place of imidazole.

The melting point of this product was 77-78°C. Reference Example 8 The same machine as Reference Example 5 was used, except that 11.0 mm of 2-ethyl-4-methylimidazole was used instead of imidazole, and 35.4 mm of 1-(stearlecarbamoyl)-2-ethyl-4-methylimidazole was used. It was evening.

The melting point of this product is 73.5-74. It was pu○. Reference Example 9 1-(Myristylcarbamoyl)imidazole 28 was prepared in the same manner as Reference Example 5 except that myristyl isocyanate 23.9 was used instead of stearyl isocyanate.
．． It took one evening.

The melting point of this product was 67-00. Example 1 The 1-(substituted carbonyl)imidazole conductor obtained in Reference Examples 1 to 5 and an aqueous emulsion of stearic acid chloride and 1-stearylimidazole for comparison were subjected to the method described below. Therefore, it was prepared and used as an internal sizing agent.

b) Collect 20 minutes of each of the above compounds and 1 day of "/Igen ETI90" (trade name of polyoxyethylene oleyl ether, manufactured by Daiichi Kogyo Seiyaku ■) in a mortar, and gradually add 179 hours of water while grinding. A dispersion was obtained.

This dispersion was passed twice through a piston type emulsifier adjusted to a discharge pressure of 300k9/mm to obtain a milky white aqueous emulsion. [o} Add each of the above compounds for 20 minutes and "Polystron 705" (trade name of an aqueous solution of cation-modified polyacrylamide with a solid content of 10%, manufactured by Arakawa Rinsan Ibaku Kogyo ■) 4
A sample of 0.0 mm was collected in a mortar, and while grinding, 140 mm of water was gradually added to obtain a dispersion.

Thereafter, a milky white aqueous emulsion was obtained using the same machine as the above-mentioned method. Next, pulp with a Rolo scale of 3 pi SR (L-BK
0.5% of the aqueous emulsion based on the pulp (based on the dry weight of the active ingredient, the same applies hereinafter) was added to the 1% aqueous slurry of P), and after stirring for 18 minutes, paper was made using a Tadupi Standard Sheet Machine.

In addition, when the aqueous emulsion is obtained by the above-mentioned method, after adding the aqueous emulsion,
"Araphix 200" (trade name of an aqueous solution of polyamide polyamine epichlorohydrin resin with a solid content of 20%,
Arakawa Forestry Chemical Industry ■) was added at 0.5% to the pulp, and 1
After praying for 5 minutes, I made paper. Pressure the obtained wet paper 3
[After being compressed and dehydrated at a temperature of 9', it was dried at a temperature of 80° for 5 minutes.
Then, the resulting paper was heated under the conditions of 2 0 and 65% RH.
The humidity was controlled day and night, and the basis weight was 60±1/day and used as a test paper material. For this paper stock, the Stekicht method (JISP8122
) was used to measure the degree of size. The results are shown in Table 1. 1. Size effect (Note) The units of numbers in the table are seconds.

Example 2 The 1-(substituted carbamoyl)imidazole derivatives obtained in Reference Examples 6 to 9 and the respective aqueous emulsions of stearylcarbamic acid chloride and stearyl isocyanate for comparison were prepared by the method of Example 1 or as described below. It was prepared according to the method and used as an internal sizing agent.

20 pieces of each of the above compounds and 202 pieces of "Araphyx 200" were collected in a mortar, and while grinding, 160 pieces of water was gradually added to obtain a dispersion.

Thereafter, a milky white aqueous emulsion was obtained in the same manner as in the method of Example 1. Next, paper making, dehydration, drying, humidity control and sizing measurements were carried out in the same manner as in Example 1.

However, when making paper, the aqueous emulsion is
When the aqueous emulsion is added, "Epomin 1000" (trade name of an aqueous solution of polyethyleneimine with a solid content of 10%*, manufactured by Nippon Shokubai IC Gaku Kogyo) is added to the pulp. After adding .5% and soaking for 18 minutes, paper was made. The measurement results of size degree are shown in Table 2.

Table 2 Size effect (Note) The units of numbers in the table are seconds.

Example 3 Commercially available high-quality paper (containing 0.2% reinforced rosin sizing agent, 1% sulfuric acid, 10% clay, sizing degree 0 seconds, basis weight 60
) to an aqueous emulsion (Reference Examples 1 and 5) at a specified concentration.
and No. 6 (prepared on the same day by the above-mentioned method) at a constant speed, immediately squeezed with a roll, dried once with hot air at 80 qo for 2 minutes, and then heated with 20 qo and 65% RH. Humidity was controlled for one day and night under these conditions.

This paper stock was measured for sizing and writability (J. TAPPI Pulp Test Method No. 12) using the Stekicht method. The results are shown in Table 3. Table 3

Claims (1)

[Claims] 1 General formula ▲ Numerical formula, chemical formula, table, etc. ▼ (In the formula, R^1 is a hydrogen atom, a phenyl group, or 1 to 20
R^2 and R^3 are hydrogen atoms or alkyl groups having 1 to 3 carbon atoms, or R^2 and R^3 are bonded to form an alkyl group having 1 to 3 carbon atoms, respectively. forms a benzene ring with the carbon atom of the imidazole ring to which it is bonded. A is a hydrophobic group having 8 to 40 hydrocarbon atoms)
A paper sizing agent comprising a 1-(substituted carbonyl)imidazole derivative represented by the following as an active ingredient. 2
The paper sizing agent according to claim 1, wherein R^1, R^2 and R^3 are hydrogen atoms or alkyl groups having 1 to 3 carbon atoms. 3. The paper sizing agent according to claim 1, wherein the hydrophobic group is a hydrocarbon group. 4. The paper sizing agent according to claim 3, wherein the hydrocarbon group is an alkyl group or an alkenyl group having 12 to 20 carbon atoms. 5. The paper sizing agent according to claim 1, wherein the hydrophobic group is a substituted amino group. 6. The paper sizing agent according to claim 5, wherein the substituted amino group is a monoalkylamino group having 12 to 20 carbon atoms. 7. The paper sizing agent according to claim 1, wherein the hydrophobic group is a substituted oxy group. 8. The paper sizing agent according to claim 7, wherein the substituted oxy group is an alkoxy group having 12 to 20 carbon atoms. 9. Claim 1, wherein the 1-(substituted carbonyl)imidazole derivative is emulsified in water with an emulsifier;
The paper sizing agent according to item 2, 3, 4, 5, 6, 7, or 8. 10. The paper sizing agent according to claim 9, wherein the emulsifier is a nonionic surfactant. 11. The paper sizing agent according to claim 9, wherein the emulsifier is a water-soluble cationic polymer protective colloid.