JPH07216784A - Paper sizing - Google Patents

Abstract

PURPOSE:To impact the paper with excellent sizing performance in paper making under a weak acidic or an alkaline condition. CONSTITUTION:To essential components consisting of 1-99%, preferably 5-70%, cationic vinyl monomer comprising a diallyl amine salt of the formula (R<1> and R<2> are each independently H or methyl; HX is an acid.) and 1-99%, preferably 30-95 %, nonionic vinyl monomer such as an aqueous solution of acryl amide, etc., a vinyl monomer such as (meth)acrylonitrile, etc., is added as a third component and the mixture is polymerized in an aqueous medium to form a copolymer having 500-10000 centipoise viscosity at 25 deg.C in 15wt.% concentration aqueous solution. The copolymer is added to an aqueous pulp slurry and a neutral rosin size which is effective in a neutral region is added and the whole is allowed to paper machining at pH6-9.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a paper sizing method. More specifically, the present invention relates to a paper sizing method using a rosin-based sizing agent in papermaking performed under pH 6 to 9 under weakly acidic or alkaline conditions.

[0002]

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

However, the alkyl ketene dimer type sizing agent has a problem that when used internally, it takes a long time for the size effect to appear after the dryer is lifted.
In the case of finished paper, it causes a problem that the paper slips. Further, the alkenyl succinic anhydride-based sizing agent has to be emulsified and dispersed immediately before use, and is inferior in workability. Further, a drawback common to both is that the price is high.

Therefore, in recent years, in order to solve the above problems, a rosin-based sizing agent (hereinafter, referred to as neutral rosin size) which is effective even in a neutral region has been developed. For example,
JP-A-62-223393 discloses a rosin modified with a polyhydric alcohol, which is used in such a ratio that the hydroxyl equivalent ratio of the polyhydric alcohol to the carboxyl group of the rosin is 0.2 to 1.5. Disclosed neutral rosin size. Further, JP-A-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 treated with a cationic vinyl monomer and an aromatic vinyl. Disclosed are neutral rosin sizes emulsified and dispersed in monomers and / or copolymers with (meth) acrylic acid esters.

[0005]

However, even these neutral rosin sizes have problems such as insufficient size effect, stains in papermaking system, and foaming due to poor fixing of the sizing agent. Further, when the paper is made at a pH of 8 or more, or when the amount of the sulfuric acid band added is 0.5% by weight or less, the size expression is insufficient.

It is an object of the present invention to overcome the shortcomings of the prior art in improving the fixing of neutral rosin size when carrying out papermaking under mildly acidic or alkaline conditions using neutral rosin size. It is to give the paper a different size effect. As a result of intensive studies to solve such problems, the present inventors have found that by using a specific water-soluble copolymer together with a neutral rosin size, excellent size in papermaking performed under conditions of pH 6-9. The present invention has been completed by finding that the property can be imparted.

[0007]

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

[0008]

(Wherein R ¹ and R ² independently represent hydrogen or methyl, and HX represents an acid), and 1 to 99 mol% of a cationic vinyl monomer and a water-soluble nonionic vinyl monomer. The present invention provides a method for sizing paper by using a copolymer containing 1 to 99 mol% as an essential component in combination with the rosin-based sizing agent.

The cationic vinyl monomer of formula (I) is
It is a salt of a secondary amine represented by diallylamine and dimethallylamine. Among them, a diallylamine salt is preferably used. Represented by HX in formula (I),
The acid constituting the salt may be either an inorganic acid or 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 preferable. Mixing diallylamine or dimethallylamine with these acids readily forms the cationic vinyl monomer (salt) of formula (I). 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 nonionic and water-soluble substance may be used, 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, especially acrylamide is preferably used.

In producing 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%, preferably the formula (I). It is preferable to use 5) to 70 mol% of the cationic vinyl monomer of 5) and 30 to 95 mol% of the water-soluble nonionic vinyl monomer. By copolymerizing only two components of the cationic vinyl monomer of formula (I) and the water-soluble nonionic vinyl monomer, a cationic copolymer is obtained.

In the copolymer used in the present invention, in addition to the above-mentioned essential components, a monomer copolymerizable therewith, particularly a vinyl monomer, may be used alone or in an amount such that the water solubility of the copolymer is not impaired. Two or more kinds can be introduced. Other monomers that can be optionally introduced include, for example, (meth) acrylonitrile, methyl (meth) acrylate, hydroxyethyl (meth) acrylate, styrene, water-insoluble nonionic monomers such as vinyl acetate, and dimethylaminoethyl. (Meth) acrylate, dimethylaminopropyl (meth) acrylamide or the like, or a quaternary compound thereof, dimethylamine, a cationic monomer such as diallyldimethylammonium chloride, (meth) acrylic acid, maleic acid, fumaric acid, itaconic acid, Examples thereof include anionic monomers such as alkali metal salts or ammonium salts, bifunctional monomers such as ethylene glycol di (meth) acrylate, and methylenebis (meth) acrylamide.

The copolymer used in the present invention can be obtained by copolymerizing the above-mentioned essential monomer components or further optional monomer components.
The production of this copolymer can be carried out by a known method, and the polymerization mode is not limited, but usually in an aqueous solution or in a mixed solvent of water and a water-soluble solvent, the polymerization reaction is carried out 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 thereof include azo compounds such as 2'-azodipropane dihydrochloride and azobisisobutyronitrile, di-t-butyl peroxide, cumene hydroperoxide, and peroxides such as hydrogen peroxide solution. Further, a known redox type initiator, for example, a combination of potassium persulfate and sodium bisulfite or a tertiary amine may be used. Further, if necessary, a known and commonly used chain transfer agent such as isopropyl alcohol or 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 is possible in the presence of oxygen, but it is preferably carried out in an atmosphere of an inert gas such as nitrogen gas. In the polymerization, an essential component, or a monomer copolymerizable with these essential components used as necessary, the polymerization may be started after charging all these components at once, or only a certain component, Alternatively, only a part of all the components may be charged to start the polymerization, and then the remaining components may be continuously or dividedly added to continue the polymerization.

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

The 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, a rosin is modified with a polyhydric alcohol, and the ratio of the hydroxyl equivalent of the polyhydric alcohol to the carboxyl group of the rosin is 0.2 to. The neutral rosin size used at a ratio of 1.5, an esterification reaction product of an alkanol tertiary amine with a rosin as described in JP-A-4-108196 is used as an α, β-unsaturated diamine. A neutral rosin size obtained by modifying with a basic acid and emulsifying and dispersing this resin with a copolymer of a cationic vinyl monomer, an aromatic vinyl monomer and / or a (meth) acrylic acid ester corresponds to this.

When sizing the paper according to the present invention, so-called internal sizing is employed in which the rosin-based sizing agent and the copolymer are added to the aqueous pulp slurry to make the paper. The addition order of the rosin-based sizing agent and the copolymer is not particularly limited, but it is effective to first add the copolymer to the pulp slurry and then to add the rosin-based sizing agent to effectively develop the sizing property. Is preferred.
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 usually in the range of 0.1 to 3% by weight, and preferably in the range of 0.3 to 1% by weight, based on the dry weight of pulp. Added to pulp slurry. Also, the copolymer is
Usually 0.02 as solids based on the dry weight of the pulp
~ 1 wt%, preferably 0.03 to 0.5 wt% is added to the pulp slurry. The paper making itself can be performed according to a usual method. For papermaking, 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 required. Also, a filler such as calcium carbonate is usually added.

[0021]

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

Synthesis Example 1

50% Diallylamine Sulfate Aqueous Solution 11.7
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 slight amount of 28% caustic soda aqueous solution. Then, the air in the apparatus was sufficiently replaced with nitrogen gas to make it oxygen-free, and 0.28 g of ammonium persulfate was added at 70 ° C. Then, while maintaining the internal temperature at 70 ° C, 50% acrylamide aqueous solution 5
1.2 g (0.36 mol) was added into the reaction system over 2 hours. Then, keep the temperature at 70 ° C for 2 hours to complete the reaction.
An aqueous solution of the cationic copolymer was obtained. The reaction rate of acrylamide was 99% or more based on the amount of unreacted monomer. The product is about 15% polymer and has a pH of 3.5, 2.
The Brookfield viscosity at 5 ° C. was 5000 cps.

Synthesis Examples 2-4

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 changed as appropriate.

[0026]

[Table 1] DAA: diallylamine sulfate AM: acrylamide

Examples 1 to 4

Pulp slurry with a concentration of 0.75% (LBK
P, Canadian Standard Freeness 410ml)
10% of heavy calcium carbonate as a filler and 0.5% of cationized starch (Kate F, manufactured by Oji National Co., Ltd.) were added to each of the pulp solids, followed by a sulfuric acid band of 0.2% and the above Synthesis Example 1. After adding each of the copolymers obtained in ~ 4 to 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.
% Added. The pulp pH at this time was 8.5. This was paper-made using a TAPPI standard sheet machine so that the basis weight would be 60 g / m ² . The obtained wet paper is 4 kg /
After dehydrating at cm ² for 7 minutes, then drying at 110 ℃ for 4 minutes,
Furthermore, the humidity was controlled for 15 hours at a temperature of 20 ° C. and a relative humidity of 65%.

Comparative Examples 1 to 4

Paper making was carried out in the same manner as in Examples 1 to 4 except that the following size fixing agents were used instead of the copolymers obtained in the above Synthesis Examples 1 to 4.

Comparative Example 1: Mannich modified product of acrylamide / acrylic acid copolymer 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 Steckigt sizing degree was measured according to JIS P 8122. The results are shown in Table 2.

[0033]

[Table 2]

[0034]

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

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[Procedure amendment]

[Submission date] March 24, 1995

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be amended] Claims

[Correction method] Change

[Correction content]

[Claims]

[Procedure Amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0009

[Correction method] Change

[Correction content]

(Wherein R ¹ and R ² independently represent hydrogen or methyl, and HX represents an acid), and 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
By the, there is provided a method of sizing paper.

[Procedure 3]

[Document name to be amended] Statement

[Correction target item name] 0013

[Correction method] Change

[Correction content]

In the copolymer used in the present invention, in addition to the above-mentioned essential components, a monomer copolymerizable therewith, particularly a vinyl monomer, may be used alone or as long as it does not impair the water solubility of the copolymer. Two or more kinds can be introduced. Other monomers that can be optionally introduced include, for example, (meth) acrylonitrile, methyl (meth) acrylate, hydroxyethyl (meth) acrylate, styrene, water-insoluble nonionic monomers such as vinyl acetate, and dimethylaminoethyl. (meth) acrylate, dimethylaminopropyl (meth) acrylamide, or their quaternized, diallyl methylamine, diallyldimethylammonium cationic monomers such as chloride, (meth)
Anionic monomers such as acrylic acid, maleic acid, fumaric acid, itaconic acid, alkali metal salts or ammonium salts thereof, and bifunctional monomers such as ethylene glycol di (meth) acrylate and methylenebis (meth) acrylamide. To be

[Procedure amendment 4]

[Document name to be amended] Statement

[Correction target item name] 0019

[Correction method] Change

[Correction content]

When sizing the paper according to the present invention, so-called internal sizing is employed in which the rosin-based sizing agent and the copolymer are added to the aqueous pulp slurry to make the paper. Added near the rosin sizing agent and a copolymer
The stand was added copolymer is first to the pulp slurry, that subsequently adding rosin sizing agent is preferable in order to effectively express the size of. The paper manufactured here has a broad meaning, and includes paper and paperboard in a narrow sense.

Claims (8)

[Claims] 1. A rosin-based sizing agent is added to an aqueous pulp slurry, and at the same time the formula (I) (In the formula, 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 and a water-soluble nonionic vinyl monomer 1 to 99 A paper sizing method, characterized in that a copolymer containing mol% as an essential component is added and the paper is made at pH 6-9. 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. A cationic vinyl monomer of formula (I)
The method according to claim 1 or 2, which is a salt of diallylamine. 4. The water-soluble nonionic vinyl monomer is acrylamide or methacrylamide.
The method according to any one of 3 above. 5. The copolymer comprises as an essential component 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.
4. The method according to any one of 4 above. 6. The method according to claim 1, wherein the copolymer further contains another vinyl monomer as a copolymerization component. 7. The method according to claim 1, wherein the copolymer has a viscosity of 500 to 10,000 centipoise at 25 ° C. when it is an aqueous solution having a concentration of 15% by weight. 8. The method according to claim 1, wherein the rosin-based sizing agent is added after the copolymer is added to the aqueous pulp slurry.