JPH064954B2 - Neutral papermaking sizing method - Google Patents

Description

TECHNICAL FIELD The present invention relates to a novel neutral papermaking sizing method.

2. Description of the Related Art Recently, in order to put into practical use a neutral papermaking method in consideration of adverse effects caused by acidic papermaking, such as deterioration of papermaking machines and deterioration of papermaking with time, a neutral papermaking sizing agent or a neutral papermaking sizing method. Regarding this, various compounds have been investigated. For example, alkenyl succinic anhydride, alkyl ketene dimer, etc. are used as a sizing agent for neutral papermaking.

However, of these, alkenyl succinic anhydride-based sizing agents have poor hydrolytic stability and therefore cannot be stored in the state of an aqueous dispersion, so they must be emulsified and dispersed immediately before the papermaking stage, resulting in poor workability. However, it has the disadvantage of being expensive. In addition, the alkyl ketene dimer type sizing agent has a drawback that the size effect immediately after papermaking is inferior because the size effect is slow to rise, and in addition, it is more expensive than the alkenyl succinic anhydride type sizing agent, so that the cost is up. There is a problem that it invites.

By the way, in the acidic papermaking method, conventionally, emulsion type sizing agents obtained by dispersing with a soap type sizing agent or a dispersant obtained by saponifying rosin or reinforced rosin with an alkali metal hydroxide have been widely used. There is. Since these sizing agents do not exhibit a good sizing effect when used as a sizing agent for neutral papermaking, it is necessary to use a sulfuric acid band as a fixing agent and to use it in an acidic region of less than pH 6. The reason why the size effect is inferior at neutral is not clear yet, but it is presumed that at pH 6 or higher, a part of the rosin or the fortified rosin migrates into water and the yield to pulp decreases. Further, in the acidic papermaking method, there is a problem that calcium carbonate, which is an inexpensive filler, cannot be used.

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention An object of the present invention is to provide a novel neutral papermaking sizing method.

The present inventors have not been able to use for conventional neutral papermaking, but in the acidic papermaking method, attention has been paid to rosin-based compounds, which have many proven results, and some technical means are applied to the rosin-based compounds to obtain the above-mentioned conventional methods. The purpose of the present invention is to develop a neutral papermaking sizing method using a rosin-based sizing agent which does not have the drawbacks of the neutral papermaking sizing agent and is satisfactory in terms of size effect, workability and cost.

Means for Solving the Problems As a result of diligent research, the present inventors have surprisingly found that an aqueous dispersion containing a specific α, β-unsaturated carboxylic acid-modified rosin ester has a pH of 7 or more under a neutral region. In particular, it has excellent sizing effect, good storage stability of the aqueous dispersion, and excellent workability because it can be used as it is for papermaking, and it is relatively inexpensive in itself, and calcium carbonate can be used. We have found that the reduction can be achieved.
The present invention has been completed based on these new findings.

That is, the present invention relates to (a) rosin, (b) C, H, O
At least one of a trihydric alcohol and a tetrahydric alcohol consisting of (c) an (alpha), (beta) -unsaturated carboxylic acid derivative are made to react sequentially or simultaneously, and the hydroxyl group of (ii) with respect to the carboxyl group equivalent of (ii). Equivalent ratio is 0.2 ~
The reaction product obtained as a charge ratio of 1.5 is a cationic fixing by sizing the water-dispersed sizing agent in the absence of aluminum sulfate or calcium carbonate when aluminum sulfate is used. PH 7 to 9 using agents
The present invention relates to a neutral papermaking sizing method characterized by being used in a neutral region.

As described above, the neutral papermaking sizing agent used in the present invention has at least one of a trihydric alcohol and a tetrahydric alcohol composed of (a) rosin, (b) C, H and O as the dispersed phase. And (c) a specific reaction product of an α, β-unsaturated carboxylic acid derivative, the reaction product esterifying a rosin with a specific amount of a specific polyhydric alcohol, and α, β -Modified with unsaturated carboxylic acid.

In the present specification, rosins mean gum rosin, tall oil rosin, utudrosine, and the like, but it is not possible to prevent partial use of hydrogenated rosin, disproportionated rosin, formaldehyde-modified rosin, etc., which are modified products thereof. . .

The esters are esterified products formed by dehydration condensation of rosins or α, β-unsaturated carboxylic acid-modified rosins with at least one trihydric alcohol and tetrahydric alcohol consisting of C, H, and O. Yes, it is a concept including complete esterified products and partially esterified products.

In the present invention, polyhydric alcohols such as C, H and O are used.
It is necessary to use at least one of the empty trihydric alcohol and tetrahydric alcohol. The intended effects of the present invention cannot be obtained with monohydric alcohols, dihydric alcohols, amino alcohols and the like. Specifically, trihydric alcohols such as glycerin, trimethylolethane, trimethylolpropane, 3-methylpentane-1,3,5-triol and tetrahydric alcohols such as pentaerythritol and diglycerin can be exemplified, and selected from these. These polyhydric alcohols may be used alone or in combination.

Further, in the present invention, it is necessary to modify with an α, β-unsaturated carboxylic acid derivative, which further improves the size effect in the neutral region. Here, as the α, β-unsaturated carboxylic acid derivative, maleic anhydride, maleic acid, maleic acid monoesters or maleic acid diesters obtained from lower alcohol and maleic anhydride, fumaric acid, N-alkylmaleimides are used. , Itaconic acid, itaconic anhydride and the like can be exemplified, and among them, maleic anhydride, maleic acid, maleic acid monoesters, itaconic acid and itaconic anhydride are preferable.

The reaction product, which is the dispersed phase in the sizing agent used in the present invention, is obtained by reacting (a) rosin with (b) the above-mentioned specific polyhydric alcohol and (c) an α, β-unsaturated carboxylic acid derivative sequentially or simultaneously. Can be obtained. Here, “sequentially” may mean that (b) is reacted with (b) and then (c) is reacted, or that (a) is reacted with (c) and then (b) is reacted. It means good.

The case where (b) is reacted after reacting (b) with (a) will be described. First, (a) rosins and (b) the polyhydric alcohols are subjected to known esterification conditions.
That is, after the both are charged, dehydration condensation may be performed under normal pressure, reduced pressure or increased pressure at a temperature of about 150 to 300 ° C. for about 3 to 40 hours while stirring, depending on the boiling point of the polyhydric alcohol.
If necessary, benzene, toluene,
It is also possible to dehydrate under azeotropic distillation using a solvent such as xylene.

In the present invention, the rosin and the polyhydric alcohol have a specific charging ratio, that is, an equivalent ratio of the hydroxyl group of the polyhydric alcohol to the carboxyl group of the rosin [-O.
H (eq) /-COOH (eq)] is 0.2 to 1.5,
It is necessary to prepare so that it is preferably 0.4 to 1.2. When the equivalent ratio is less than 0.2, the size effect in the neutral region of the resulting sizing agent is not sufficiently improved, which is not preferable. Further, when the equivalent ratio exceeds 1.5, a large amount of free hydroxyl groups remains in the polyhydric alcohol ester of rosin to be produced. However, the size effect is reduced, which is not preferable.

By the above reaction, usually, all of the hydroxyl groups of the polyhydric alcohols are esterified with the carboxyl groups of rosins, complete esterified products, partially esterified products in which some of the hydroxyl groups are esterified, and various unreacted raw materials. A mixture forms. In the present invention, this is then modified with (c) α, β-unsaturated carboxylic acid derivative according to known modification conditions. That is, after adding (C) to the reaction products of (A) and (B) obtained above, the reaction can be carried out under normal reaction conditions, for example, at a temperature of about 150 to 250 ° C. and 0.5
The desired reaction product is obtained by reacting for about 24 hours.

The amount of the (c) α, β-unsaturated carboxylic acid derivative used in the above reaction is usually 1 mol or less, preferably about 0.05 to 0.75 mol, per 1 mol of the (i) rosin. It is particularly preferably about 0.10 to 0.70 mol.

Further, (b) can be reacted after (a) is reacted with (c). In this case, (a) rosins are modified with (c) an α, β-unsaturated carboxylic acid derivative under the same modification conditions as described above, and the resulting reaction product is subjected to the above esterification conditions under the same esterification conditions as described above. The desired reaction product can be obtained by esterification with the polyhydric alcohol (b) within the equivalent ratio range.

Furthermore, (b) and (c) can be reacted simultaneously with (a). In this case, (a) rosins, (b) the polyhydric alcohol and (c) α, β-in the equivalent ratio range.
The desired reaction product is obtained by reacting the unsaturated carboxylic acid at a temperature of about 150 to 300 ° C. for about 3 to 40 hours.

Thus, a reaction product which is a dispersion phase of the neutral papermaking sizing agent used in the present invention is obtained. This reaction product is
Usually, various mixtures of α, β-unsaturated carboxylic acid-modified rosin esters, rosin esters, α, β-unsaturated carboxylic acid-modified rosins and unreacted raw materials are used. As long as it is a reaction product, it can be used as it is as a dispersed phase of the sizing agent.

The above reaction product is usually an α, β-unsaturated carboxylic acid modified rosin ester (completely esterified product and / or partially esterified product) and a rosin ester not modified with the carboxylic acid (completely esterified product and ( Or) as a total weight of partial esterified product), 20% by weight based on the total solid content
It contains the above degree. If necessary, α, β-unsaturated carboxylic acid-modified rosins, rosins and the like may be added to the reaction product. In this case, it is preferable that the total weight of the α, β-unsaturated carboxylic acid-modified rosin ester and the rosin ester is 20% by weight or more based on the total solid content even after the addition, and the performance of the obtained sizing agent is further considered. If so, it is more preferable to set the content to 40% by weight or more. If the ratio of these esters is not found to be 20% by weight, the size effect is reduced, which is not preferable.

The neutral papermaking sizing agent used in the present invention is an aqueous dispersion of the above reaction product or a mixture thereof with an α, β-unsaturated carboxylic acid-modified rosin, by a so-called high pressure emulsification method, an inversion method or the like. It can be manufactured by using a liquid. That is, in the case of the high pressure emulsification method, the above reaction products forming a dispersed phase are dissolved in a solvent such as benzene and toluene, and then an emulsifier and warm water are mixed and emulsified using a high pressure emulsifier. After that, the solvent can be distilled off to obtain an aqueous dispersion.
Further, in the case of the inversion method, after sufficiently kneading the reaction product and the like with an emulsifier, warm water is gradually added dropwise under melting and stirring, and the phase is inverted to form an aqueous dispersion without using any solvent. Can be obtained.

As the emulsifier that can be used in the above method, various surfactants,
Protective colloids and the like can be used without particular limitation. Examples of the surfactant include an alkylbenzene sulfonate, an alkyl sulfate, an anionic emulsifier such as rosin soap, a nonionic emulsifier such as polyethylene oxide and polypropylene oxide, a polyoxyethylene alkylphenyl ether sulfate, and a polyoxyethylene alkylphenol. Nonionic-anionic emulsifiers such as phenyl ether sulfonates, polyoxyethylene alkylphenyl ether sulfosuccinates, polyoxyethylene distyryl phenyl ether sulfates, polyoxyethylene distyryl phenyl ether sulfosuccinates, etc. It can be illustrated. Also,
Examples of the protective colloid include casein, lecithin, polyvinyl alcohol, various modified starches and the like. Furthermore, a fixing agent described below can be added in advance during emulsification. According to the above method, an aqueous dispersion having a solid content of about 10 to 50% by weight can usually be easily produced, and this can be used after diluting it if necessary.

The case where the sizing agent obtained above is applied to a neutral papermaking method will be described below. The thus obtained aqueous dispersion which is the neutral papermaking solution sizing agent used in the present invention, contains a filler,
It is added to the pulp slurry together with a fixing agent, a paper strengthening agent and the like. The amount of the aqueous dispersion added is usually 0.0
About 5 to 2.0% by weight (solid content conversion), preferably 0.1.
It is set to 1 to 1.0% by weight. If the amount is less than 0.05% by weight, a sufficient size effect is hardly exhibited, and if the amount is more than 2.0% by weight, the significance of addition in excess is not recognized, and thus both are not preferable. In the present invention, the pulp slurry is not added with aluminum sulfate, or when aluminum sulfate is used, calcium carbonate is present to make paper in a neutral region of pH 7-9. The filler that can be used is not particularly limited, and any conventionally known filler can be used. Furthermore, calcium carbonate, which could not be used in the conventional acidic papermaking method, can be preferably used, and thus the papermaking cost can be reduced. There is an advantage that can greatly contribute to. As the fixing agent, various known cationic fixing agents used for neutral sizing agents such as alkyl ketene dimer and alkenyl succinic anhydride can be used as they are. For example, cationized starch, epichlorohydrin modified product of polyamide polyamine resin, epichlorohydrin modified product of dicyandiamide resin, epichlorohydrin modified product of styrene-dimethylaminoethyl methacrylate copolymer, Mannich modified product of polyacrylamide, acrylamide-dimethylaminoethyl methacrylate copolymerization product. Examples thereof include coalesce products, Hoffman degradation products of polyacrylamide, and copolymers of dialkyldiallylammonium chloride and sulfur dioxide.

Although the sizing agent used in the present invention can exhibit excellent sizing performance by itself, a known neutral sizing agent, for example, epichlorohydrin modified product of styrene-dimethylaminoethyl methacrylate copolymer, alkenyl succinic anhydride is used. It is also possible to use an alkyl ketene dimer, a fatty acid-polyalkyl polyamine condensate modified with epichlorohydrin, and the like.

In the present invention, it is appropriately determined within the range of pH 7 to 9 at the time of paper making, and within this range, excellent size effect can be exerted at all. Outside of this range, the desired effect of the present invention is not sufficient.

EFFECTS OF THE INVENTION According to the present invention, the following remarkable effects are exhibited.

(1) A very excellent size effect can be obtained in a neutral range of pH 7 or higher, and defects due to acidic sizing can be eliminated.

(2) The sizing agent used in the present invention has good storage stability,
Excellent workability as it can be used as it is for papermaking.

(3) The sizing agent used in the present invention is less expensive than conventional sizing agents for neutral papermaking, and in combination with the fact that calcium carbonate can be used, the papermaking cost can be greatly reduced.

EXAMPLES Hereinafter, the present invention will be described more specifically with reference to Production Examples, Examples and Comparative Examples, but the present invention is not limited to these examples. In the examples, all parts and% are by weight unless otherwise specified.

Production Example 1 100 parts of gum rosin having an acid value of 170 and 8 parts of glycerin (equivalent charge ratio (-OH / -COO) were placed in a 1-liter flask equipped with a stirrer, a thermometer, a nitrogen inlet tube, a water separator and a condenser.
H) = 0.86) was charged, the mixture was heated to 250 ° C. under a nitrogen stream, and an esterification reaction was carried out at the same temperature for 12 hours to obtain a reaction product having a softening point of 86 ° C. and an acid value of 32. Next, the reaction product was heated to 180 ° C., 9 parts of maleic anhydride was added, and the mixture was heated and kept at 210 ° C. for 2 hours to obtain a reaction product having a softening point of 109 ° C. and an acid value of 122.

Production Example 2 In the same manner as in Production Example 1 except that the amount of glycerin charged was changed to 2 parts in Production Example 1 (equivalent ratio = 0.22).
A reaction product having a softening point of 96 ° C. and an acid value of 212 was obtained.

Production Example 3 In the same manner as in Production Example 1, except that the amount of glycerin charged was changed to 4 parts (equivalent ratio = 0.43) in Production Example 1.
A reaction product having a softening point of 102 ° C. and an acid value of 183 was obtained.

Production Example 4 In the same manner as in Production Example 1, except that the amount of glycerin charged was 6 parts (equivalent ratio = 0.65) in Production Example 1.
A reaction product having a softening point of 105 ° C. and an acid value of 153 was obtained.

Production Example 5 In the same manner as in Production Example 1, except that the amount of glycerin charged was 12 parts (equivalent ratio = 1.29) in Production Example 1.
A reaction product having a softening point of 115 ° C. and an acid value of 90 was obtained.

Production Example 6 Except that in Production Example 1, the same amount of tall oil rosin having an acid value of 170 was used instead of gum rosin (equivalent ratio = 0.86).
In the same manner as in Production Example 1, a reaction product having a softening temperature of 100 ° C. and an acid value of 124 was obtained.

Production Example 7 A reaction product having a softening point of 99 ° C. and an acid value of 86 was obtained in the same manner as in Production Example 1 except that the amount of maleic anhydride charged in Production Example 1 was changed to 5 parts.

Production Example 8 In the same manner as in Production Example 1 except that the amount of maleic anhydride charged was 16 parts in Production Example 1, the softening point was 122 ° C.,
A reaction product having an acid value of 185 was obtained.

Production Example 9 100 parts of gum rosin having an acid value of 170 and 9 parts of maleic anhydride were heated and kept at 210 ° C. for 2 hours, then 8 parts of glycerin (equivalent ratio = 0.86) was added, and the mixture was heated to 250 ° C. and esterified for 12 hours. The reaction was carried out to obtain a reaction product having a softening point of 116 ° C. and an acid value of 117.

Production Example 10 100 parts of gum rosin having an acid value of 170, 9 parts of maleic anhydride and 8 parts of glycerin (equivalent ratio = 0.86) were added, and 250
The reaction product was heated at 0 ° C. and reacted for 12 hours to obtain a reaction product having a softening point of 118 ° C. and an acid value of 115.

Production Example 11 Fumaric acid 1 in place of maleic anhydride in Production Example 1
A reaction product having a softening point of 130 ° C. and an acid value of 122 was obtained in the same manner as in Production Example 1 except that 0.7 part was used.

Production Example 12 A paste-like reaction product having an acid value of 28 was obtained in the same manner as in Production Example 1 except that 15.8 parts of maleic acid diethyl ester was used in place of maleic anhydride.

Production Example 13 A reaction product having a softening point of 79 ° C. and an acid value of 70 was obtained in the same manner as in Production Example 1 except that 13.2 parts of maleic acid monoethyl ester was used in place of maleic anhydride in Production Example 1. .

Production Example 14 A reaction product having a softening point of 110 ° C. and an acid value of 120 was obtained in the same manner as in Production Example 1 except that 10.3 parts of itaconic anhydride was used instead of maleic anhydride.

Production Example 15 In the same manner as in Production Example 1 except that 10.4 parts of trimethylolethane was used in place of glycerin in Production Example 1 (equivalent ratio = 0.86) and the ester generation reaction was carried out at 250 ° C. for 30 hours. A reaction product having a softening point of 110 ° C. and an acid value of 120 was obtained.

Production Example 16 In the same manner as in Production Example 1 except that 11.7 parts of trimethylolpropane was used instead of glycerin in Production Example 1 (equivalent ratio = 0.86), and the esterification reaction was carried out at 250 ° C. for 30 hours. Thus, a reaction product having a softening point of 113 ° C. and an acid value of 120 was obtained.

Production Example 17 In place of glycerin in Production Example 1, diglycerin 1 was used.
A reaction product having a softening point of 114 ° C. and an acid value of 121 was prepared in the same manner as in Production Example 1 except that 0.8 part was used (equivalent ratio = 0.86) and the esterification reaction was carried out at 250 ° C. for 30 hours. Obtained.

Production Example 18 Production Example 1 except that 8.85 parts of pentaerythritol were used in place of glycerin in Production Example 1 (equivalent ratio = 0.86), and the ester generation reaction was carried out at 250 ° C. for 30 hours.
Similarly to the above, a reaction product having a softening point of 122 ° C. and an acid value of 119 was obtained.

Comparative Production Example 1 100 parts of gum rosin having an acid value of 170 and 9 parts of maleic anhydride were heated at 210 ° C. for 2 hours to obtain a reaction product having a softening point of 98 ° C. and an acid value of 252.

Comparative Production Example 2 In Production Example 1, only esterification was carried out without adding maleic anhydride to obtain a reaction product having a softening point of 86 ° C. and an acid value of 32.

Comparative Production Example 3 In the same manner as in Production Example 1, except that the amount of glycerin charged in Production Example 1 was changed to 1 part (equivalent ratio = 0.11).
A reaction product having a softening point of 93 ° C. and an acid value of 232 was obtained.

Comparative Production Example 4 In Production Example 1, the charged amount of glycerin was 20 parts (equivalent ratio = 2.2), and the esterification reaction was 30 at 250 ° C.
A softening point of 1 was obtained in the same manner as in Production Example 1, except that the softening point was changed.
A reaction product having an acid value of 60 at 19 ° C. was obtained.

Comparative Production Example 5 The same as Production Example 1 except that 8.1 parts of ethylene glycol was used instead of glycerin in Production Example 1 (equivalent ratio = 0.86), and the esterification reaction was carried out at 200 ° C. for 20 hours. Thus, a reaction product having a softening point of 88 ° C. and an acid value of 130 was obtained.

Comparative Production Example 6 Similar to Production Example 1 except that 12.5 parts of neopentyl glycol was used in place of glycerin in Production Example 1 (equivalent ratio = 0.86), and the esterification reaction was carried out at 200 ° C. for 20 hours. Then, a reaction product having a softening point of 91 ° C. and an acid value of 128 was obtained.

Comparative Production Example 7 Production Example 1 except that 12.9 parts of triethanolamine was used in place of glycerin in Production Example 1 (equivalent ratio = 0.86) and the esterification reaction was carried out at 250 ° C. for 30 hours.
Similarly to the above, a reaction product having a softening point of 93 ° C. and an acid value of 127 was obtained.

Comparative Production Example 8 Except that 22.6 parts of tris (2-hydroxyethyl) isocyanurate was used in place of glycerin in Production Example 1 (equivalent ratio = 0.86), and the esterification reaction was carried out at 250 ° C. for 30 hours. , Softening point 11 in the same manner as in Production Example 1.
A reaction product having an acid value of 126 at 2 ° C. was obtained.

Examples 1 to 18 200 parts of each reaction product obtained in Production Examples 1 to 18 was dissolved in 200 parts of toluene, and an emulsifier (polyoxyethylene distyrylphenyl ether sulfate ammonium salt) 10
And 800 parts of warm water (60 ° C.) were mixed and emulsified using a high pressure emulsifying machine, then toluene was distilled off to prepare an aqueous dispersion having a concentration of 21%.

Using each of the above-obtained aqueous dispersions which are the sizing agents for neutral papermaking used in the present invention, papermaking was performed according to the neutral papermaking sizing method of the present invention, and the size performance was examined by the following method.

<Method A> Pulp (L-BKP) was converted to Canadian Standard Standard
It was beaten to a freeness of 450 ml to give a 1% slurry.
Calcium carbonate (Sankyo Milling Co., Ltd., trade name "ESCALON # 100") as a filler was added to the slurry in an amount of 20% in terms of solid content with respect to the pulp, and 1% of aluminum sulfate and cationized starch (Oji National ( Co., Ltd., trade name "CaTo 15") was added 1%, and then the sizing agent obtained in each example was added to the pulp in an amount of 0.3% to obtain a filler retention agent (made by Allied Colloid Limited), 0.02% of trade name "Percoll 47") was added and uniformly dispersed. At this time, the pH of the pulp slurry was 7.8.
The resulting slurry was made into paper using a Tappi Standard sheet machine so that the basis weight was 70 g / m ² . Then, the obtained wet paper was compressed and dehydrated, dried at 100 ° C. for 1 minute, conditioned under a condition of relative humidity of 65% for 24 hours, and then each size degree (second) was measured by the Steckigt method (JIS P8122). It was measured.

<Method B> In Method A, the size degree (seconds) was measured in the same manner except that aluminum sulfate was not used. The pulp slurry had a pH of 8.2 at this time.

<Method C> Pulp (L-BKP) was added to Canadian Standard Standard.
It was beaten to a freeness of 450 ml to give a 1% slurry.
Polyamide polyamine-based cationic polymer (manufactured by Arakawa Chemical Industry Co., Ltd., trade name “Arafix-1
00 ") was added to the pulp in an amount of 0.3% in terms of solid content, and the sizing agent obtained in each example was added to the pulp in an amount of 0.
4% was added and dispersed uniformly. At this time, the pH of the pulp slurry was 7.2. The obtained slurry was paper-made by the above method, dried and conditioned, and each sizing degree (second) was measured by the Steckit method.

Comparative Examples 1 to 8 Using the respective reaction products obtained in Comparative Production Examples 1 to 8, an aqueous dispersion having a concentration of 21% was prepared in the same manner as in Example 1.

Using the sizing agent of each comparative example obtained above, papermaking was performed in the same manner as in the example, and the sizing performance was examined.

The test results are shown in Table 1.

Comparative columns 9 to 11 Comparative examples 9 to 11 were carried out in accordance with the following method using each of the aqueous dispersions of Examples 1, 2 and 8 which were the present invention neutral paper sizing agents.
No. 11 acidic papermaking sizing was performed and its size performance was investigated.

<Method D> Paper making is performed in the same manner as in Method C, except that 0.5% by weight of aluminum sulfate is added to the pulp in place of the polyamide polyamine-based cationic polymer.
Each size degree (second) was measured. The pulp slurry had a pH of 5.5 at this time.

<Method E> Paper making is performed in the same manner as in Method C except that aluminum sulfate is added to the pulp in an amount of 2.0% in terms of solid content in place of the polyamide polyamine-based cationic polymer.
Each size degree (second) was measured. The pH of the pulp slurry at this time was 4.5.

The results are shown in Table 2.

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Claims (1)

[Claims] 1. (a) At least one trihydric alcohol and a tetrahydric alcohol consisting of (b) C, H, and O and (c) an α, β-unsaturated carboxylic acid derivative are sequentially added to rosins. Alternatively, the reaction is carried out simultaneously, and the ratio of the hydroxyl group equivalent of (b) to the carboxyl group equivalent of (a) is 0.2 to 1.5.
The reaction product obtained as a charging ratio is such that the sizing agent is dispersed in water in the absence of aluminum sulfate, or in the case of using aluminum sulfate, calcium carbonate is present to form a cationic fixing agent. A neutral papermaking sizing method characterized by being used in a neutral range of pH 7-9.