JP3351084B2 - How to size paper - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for sizing paper. More specifically, the present invention relates to a paper sizing method using a rosin-based sizing agent in papermaking performed under weakly acidic or alkaline conditions of pH 6 to 9.

[0002]

2. Description of the Related Art Alkaline soap-type rosin sizing agents have been widely used as internal sizing agents. The so-called neutral papermaking has been widely performed. The alkali soap type rosin-based sizing agent does not show a sufficient effect in this neutral papermaking, and has a problem. Instead,
Various neutral sizing agents for internal addition that can be used in a neutral system have been proposed, for example, alkyl ketene dimer and alkenyl succinic anhydride are generally used.

However, the alkyl ketene dimer-based sizing agent has a problem that when used internally, it takes a long time for the size effect to be exhibited after the drier is lifted.
This causes a problem that the paper slips on the finished paper. Further, the alkenyl succinic anhydride-based sizing agent must be emulsified and dispersed immediately before use, resulting in poor workability. A further disadvantage common to both is that it is expensive.

Therefore, in recent years, rosin-based sizing agents (hereinafter referred to as neutral rosin size) which are effective even in the neutral region have been developed to solve the above-mentioned problems. For example,
JP-A-62-223393 discloses a rosin modified with a polyhydric alcohol. The rosin is used at a ratio of the hydroxyl group equivalent of the polyhydric alcohol to the carboxyl group of the rosin of 0.2 to 1.5. Neutral rosin size. Japanese Patent Application Laid-Open No. 4-108196 discloses that an esterification reaction product of an alkanol tertiary amine and a rosin is modified with an α, β-unsaturated dibasic acid, and this resin is converted into a cationic vinyl monomer and an aromatic vinyl monomer. A neutral rosin size emulsified and dispersed in a copolymer with a monomer and / or a (meth) acrylate is disclosed.

[0005]

However, even in these neutral rosin sizes, there are problems such as insufficient size effect, stains in papermaking system, foaming, etc. due to poor fixing of the sizing agent. Furthermore, when papermaking was carried out at pH 8 or more, or when papermaking was carried out with the addition amount of the sulfuric acid band being 0.5% by weight or less, the size development was insufficient.

An object of the present invention is to improve the fixation of neutral rosin size by overcoming the drawbacks of the prior art in performing papermaking under mildly acidic or alkaline conditions using neutral rosin size. It is to provide a great size effect to paper. The present inventors have conducted intensive studies to solve such problems, and as a result of using a specific water-soluble copolymer together with neutral rosin size, excellent size in papermaking performed under conditions of pH 6 to 9. The inventors have found that the property can be imparted, and have reached the present invention.

[0007]

That is, according to the present invention, a rosin-based sizing agent is added to an aqueous pulp slurry, and a pH of 6 to
In making the paper under the conditions of 9, the formula (I)

[0008]

Wherein R ¹ and R ² each independently represent hydrogen or methyl, and HX represents an acid, from 1 to 99 mol% of a cationic vinyl monomer and a water-soluble nonionic vinyl monomer. the copolymer was 99 mol% as essential components, this in combination with the rosin-based sizing agent
Thus, a method for sizing paper is provided.

The cationic vinyl monomer of the formula (I) is
It is a salt of a secondary amine represented by diallylamine and dimethallylamine. Of these, diallylamine salts are preferably used. HX in formula (I),
The acid constituting the salt may be any of an inorganic acid and an organic acid,
Examples of the inorganic acid include hydrochloric acid, sulfuric acid, nitric acid, and phosphoric acid, and examples of the organic acid include acetic acid, formic acid, oxalic acid, and propionic acid. Generally, hydrochloric acid, sulfuric acid and the like are preferred. By mixing diallylamine or dimethallylamine with these acids, cationic vinyl monomers (salts) of formula (I) are readily formed. These cationic vinyl monomers may be used alone or in combination of two or more.

The nonionic vinyl monomer, which is another essential component of the copolymer, has a vinyl bond,
Any material may be used as long as it is nonionic and shows water solubility, and examples thereof include acrylamide, methacrylamide, and vinyl alcohol. These nonionic vinyl monomers may be used alone or in combination of two or more. Among them, acrylamide or methacrylamide, particularly acrylamide, is preferably used.

In preparing the copolymer, the cationic vinyl monomer of the formula (I) and the water-soluble nonionic vinyl monomer are each used in the range of 1 to 99 mol%, but preferably the formula (I) It is preferred to use 5 to 70 mol% of the cationic vinyl monomer and 30 to 95 mol% of the water-soluble nonionic vinyl monomer. By copolymerizing only two components, a cationic vinyl monomer of the formula (I) and a water-soluble nonionic vinyl monomer, a cationic copolymer is obtained.

The copolymer used in the present invention may contain, in addition to the above essential components, one or more monomers copolymerizable therewith, in particular, a vinyl monomer, so long as the water solubility of the copolymer is not impaired. Two or more types can be introduced. Other monomers that can be optionally introduced include, for example, water-insoluble nonionic monomers such as (meth) acrylonitrile, methyl (meth) acrylate, hydroxyethyl (meth) acrylate, styrene, vinyl acetate, and dimethylaminoethyl. (meth) acrylate, dimethylaminopropyl (meth) acrylamide, or their quaternized, diallyl methylamine, diallyldimethylammonium cationic monomers such as chloride, (meth)
Examples include anionic monomers such as acrylic acid, maleic acid, fumaric acid, and itaconic acid, alkali metal salts or ammonium salts thereof, and bifunctional monomers such as ethylene glycol di (meth) acrylate and methylenebis (meth) acrylamide. Can be

The copolymer used in the present invention can be obtained by copolymerizing essential monomer components as described above or further arbitrary monomer components.
The production of this copolymer can be carried out by a known method, and the type of polymerization is not limited.However, usually, the polymerization reaction is carried out in an aqueous solution or a mixed solvent of water and a water-soluble solvent in the presence of a polymerization initiator. Is preferably performed.

As the polymerization initiator, those usually used can be used. For example, persulfates such as ammonium persulfate and potassium persulfate, 2,2'-diamidino-2,
Examples include azo compounds such as 2'-azodipropane dihydrochloride and azobisisobutyronitrile, and peroxides such as di-t-butyl peroxide, cumene hydroperoxide, and hydrogen peroxide. Known redox initiators, for example, a combination of potassium persulfate and sodium bisulfite or a tertiary amine can also be used. Further, if necessary, known and commonly used chain transfer agents such as isopropyl alcohol and allyl alcohol can be used.

The polymerization is usually carried out at a temperature of 10 to 100 ° C., preferably 40 to 90 ° C., for about 1 to 20 hours. This polymerization can be performed in the presence of oxygen, but is preferably performed in an atmosphere of an inert gas such as nitrogen gas. In the polymerization, the essential components, or monomers that can be copolymerized with these essential components used as necessary, may start the polymerization after charging all of these components collectively, or only certain components, Alternatively, after starting polymerization by charging only a part of all the components, the remaining components may be added continuously or in divided portions to continue the polymerization.

Among the thus obtained copolymers, those having a 15% by weight aqueous solution having a viscosity at 25 ° C. in the range of 500 to 10,000 centipoise,
Particularly, those having a range of 2000 to 7000 centipoise are preferable. When the viscosity at 25 ° C. of the 15% by weight aqueous solution is 500 centipoise or less, the size effect is not sufficient, and when the viscosity exceeds 10,000 centipoise, it becomes difficult to handle the copolymer.

A rosin-based sizing agent suitable for use in the present invention is one prepared for the purpose of being effective in papermaking under weakly acidic or alkaline conditions, that is, a neutral rosin size. For example, as described in JP-A-62-223393, rosins are modified with polyhydric alcohols, and the ratio of the hydroxyl group equivalent of the polyhydric alcohol to the carboxyl group of the rosins is 0.2 to 0.2. Neutral rosin size used at a ratio of 1.5, an esterification reaction product of an alkanol tertiary amine and a rosin as described in JP-A-4-108196 was converted to an α, β-unsaturated diamine. A neutral rosin size obtained by denaturing with a basic acid and emulsifying and dispersing this resin with a copolymer of a cationic vinyl monomer and an aromatic vinyl monomer and / or a (meth) acrylate ester corresponds to this.

In sizing the paper according to the present invention, so-called internal sizing, in which a rosin-based sizing agent and a copolymer are added to an aqueous pulp slurry to make paper, is employed. Added near the rosin sizing agent and a copolymer
For this reason, it is preferable to first add the copolymer to the pulp slurry, and then add a rosin-based sizing agent in order to effectively develop sizing properties. The paper manufactured here has a broad meaning and includes paper and paperboard in a narrow sense.

In the internal sizing, the rosin-based sizing agent is used in a solid content of usually 0.1 to 3% by weight, preferably 0.3 to 1% by weight, based on the dry weight of the pulp. Added to pulp slurry. The copolymer is
Usually 0.02 as solids, based on the dry weight of the pulp
It is added to the pulp slurry in the range of .about.1% by weight, preferably in the range of .03-0.5% by weight. Papermaking itself can be performed according to a usual method. In making paper, sulfuric acid band, paper strength enhancer, drainage improver, retention improver, etc.
Further, other neutral sizing agents such as alkyl ketene dimer and alkenyl succinic anhydride can be added as necessary. Usually, a filler such as calcium carbonate is also blended.

[0021]

EXAMPLES The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to these examples. The percentages in the examples represent% by weight unless otherwise specified.

Synthesis Example 1

11.7 aqueous 50% diallylamine sulfate solution
g (0.04 mol) and 144.1 g of ion-exchanged water were charged into a reactor equipped with a stirrer, and the pH was adjusted to 7.0 with a trace amount of a 28% aqueous sodium hydroxide solution. Next, the air in the apparatus was sufficiently replaced with nitrogen gas to make it oxygen-free, and then 0.28 g of ammonium persulfate was added at 70 ° C. Subsequently, while maintaining the internal temperature at 70 ° C., a 50% aqueous acrylamide solution 5
1.2 g (0.36 mol) was added to the reaction system over 2 hours. After that, the reaction was completed by keeping the temperature at 70 ° C. for 2 hours.
An aqueous solution of a cationic copolymer was obtained. From the quantification of the unreacted monomer, the conversion of acrylamide was 99% or more. The product has a polymer content of about 15% and a pH of 3.5,2.
The Brookfield viscosity at 5 ° C. was 5000 cps.

Synthesis Examples 2 to 4

Polymerization was carried out in the same manner as in Synthesis Example 1 except that the composition of the cationic copolymer was changed as shown in Table 1. The amount of ammonium persulfate for controlling the viscosity was appropriately changed each time.

[0026]

[Table 1] DAA: diallylamine sulfate AM: acrylamide

Examples 1-4

Pulp slurry having a concentration of 0.75% (LBK)
P, Canadian Standard Freeness 410ml)
, 10% of heavy calcium carbonate and 0.5% of cationized starch (Kate F, manufactured by Oji National Co., Ltd.) were added as fillers to the pulp solids, and then 0.2% of a sulfate band and the above Synthesis Example 1 were added. After adding the copolymers obtained in (1) to (4) in an amount of 0.05% in terms of solid content, neutral rosin size (Size Pine NT-80, manufactured by Arakawa Chemical Industry Co., Ltd.) was adjusted to 0.4.
% Was added. The pulp pH at this time was 8.5. This was paper-made using a TAPPI standard sheet machine so as to have a basis weight of 60 g / m ² . 4 kg of the obtained wet paper
After dehydration for 7 minutes in cm ² , dried at 110 ° C for 4 minutes,
Further, the humidity was controlled at a temperature of 20 ° C. and a relative humidity of 65% for 15 hours.

Comparative Examples 1-4

Papermaking was carried out in the same manner as in Examples 1 to 4 except that the size fixing agents shown below were used instead of the copolymers obtained in Synthesis Examples 1 to 4.

Comparative Example 1: Modified acrylamide / acrylic acid copolymer Mannich Comparative Example 2: Acrylamide / quaternized dimethylaminoethyl methacrylate copolymer Comparative Example 3: Styrene / dimethylaminoethyl methacrylate copolymer Comparative Example 4: Polyamide polyamine resin epichlorohydrin modified product

For each of the papers obtained in Examples 1 to 4 and Comparative Examples 1 to 4, the degree of Stigecht sizing was measured in accordance with JIS P8122. Table 2 shows the results.

[0033]

[Table 2]

[0034]

According to the present invention, a copolymer comprising a specific cationic vinyl monomer and a water-soluble nonionic vinyl monomer as essential components can be used in combination with a rosin-based sizing agent to form a weakly acidic or alkaline paper. By applying, an excellent size effect can be imparted to paper.

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) D21H 17/00-27/42

Claims (7)

(57) [Claims] 1. An aqueous pulp slurry having the formula (I) (Wherein R ¹ and R ² each independently represent hydrogen or methyl, and HX represents an acid) 1 to 99 mol% of a cationic vinyl monomer represented by the following formula: After adding a copolymer having mol% as an essential component , a rosin-based sizing agent was added, and the pH was adjusted to 6%.
A paper sizing method characterized by making a paper according to any one of (1) to (9). 2. The method according to claim 1, wherein the rosin-based sizing agent is prepared for the purpose of being effective in papermaking under weakly acidic or alkaline conditions. 3. The method according to claim 1, wherein the cationic vinyl monomer of the formula (I) is
3. The method according to claim 1, which is a salt of diallylamine. 4. The method according to claim 1, wherein the water-soluble nonionic vinyl monomer is acrylamide or methacrylamide.
3. The method according to any one of 3. 5. The copolymer according to claim 1, wherein said copolymer comprises 5 to 70 mol% of a cationic vinyl monomer of the formula (I) and 30 to 95 mol% of a water-soluble nonionic vinyl monomer.
5. The method according to any one of 4. 6. The method according to claim 1, wherein the copolymer further contains another vinyl monomer as a copolymer component. 7. The method according to claim 1, wherein the copolymer has a viscosity of 500 to 10,000 centipoise at 25 ° C. when the copolymer is a 15% by weight aqueous solution.