JPH0765280B2 - Sizing composition for papermaking - Google Patents

Description

TECHNICAL FIELD The present invention relates to a sizing composition for papermaking. More specifically, the present invention relates to a novel papermaking sizing composition which can be used in the neutral or alkaline range of papermaking water and has good dispersion stability of ketene dimer fine particles.

[Conventional technology]

Conventionally, rosin or reinforced rosin (maleated rosin) has been widely used as a sizing agent for papermaking. However, this rosin-based sizing agent has many problems because it requires fixing with aluminum sulfate. That is, fixing with aluminum sulfate is performed by using the papermaking water during papermaking.
Since the pH is low (acidic), the papermaking machine is greatly damaged, the printing suitability of the paper is deteriorated, and there are drawbacks such as fear of discoloration due to long-term storage of the paper and heavy load of wastewater treatment.

Further, when calcium carbonate is used as the filler, the rosin-based sizing agent cannot be used because the calcium carbonate decomposes in an acidic solution. Calcium carbonate is cheaper than talc, is one of the most abundant resources in Japan, is easily available, and has high whiteness, so it is known to be effective when used as a filler for paper, but the above Currently, its use is extremely limited due to the above reasons. Therefore, it has been desired to develop a neutral papermaking sizing agent that overcomes the above-mentioned drawbacks and can reduce wastewater treatment without deteriorating the paper quality and can use calcium carbonate.

In order to achieve this purpose in recent years, various neutral sizing agents have been proposed, but among them, sizing agents in which a ketene dimer is dispersed in water in a colloidal form are considered promising.
Many patents have been filed.

[Problems to be solved by the invention]

However, despite these many research efforts, ketene dimer sizing is slow to develop the size effect and that ketene dimer microparticles are difficult to maintain as a stable dispersion. It has drawbacks.

Generally, when a ketene dimer type sizing agent is used, the sizing performance immediately after papermaking is poor, and it is said that time is required to obtain sufficient sizing performance compared to the amount of the sizing agent used. This problem is generally pointed out by the expression that the rise of the size effect is poor, but it is easily imagined that this poor rise of the size effect particularly leads to the following defects. That is, in the case of coated paper, an internally added sizing agent is used to control the amount of liquid absorbed in the coating process. At present, coating is often performed continuously from papermaking, and in this case, it is completely useless unless the size effect is exhibited immediately after the wet paper is dried (immediately after papermaking). The ketene dimer sizing agent has excellent properties such as being usable in the neutral range, producing a sizing effect with a small amount of addition, and obtaining high-sized paper. It is currently limited.

In addition, it should be understood that sufficient consideration must be given to the dispersion stability, storage stability, especially mechanical stability of the sizing composition. The mechanical stability refers to stability against mechanical share from the outside during transportation of the sizing agent or use of the sizing agent, and is particularly important among dispersion stability. However, such dispersion stability is improved by lowering the concentration of active ingredient in the sizing composition. However, a product having a low concentration of the active ingredient is costly for transportation, filling, etc., and requires a large-capacity container for storage, which is extremely uneconomical. Therefore, in the paper manufacturing industry, there is a demand for the development of a sizing agent having a high effective concentration, good dispersion stability, good rise of size performance, and excellent size performance effect.

[Means for solving problems]

In view of the above situation, the present inventors have a high concentration of the active ingredient, dispersion stability, storage stability good aqueous dispersion,
In particular, as a result of earnest research to find a ketene dimer type sizing composition for papermaking which has a good rise in size performance and has an excellent size performance effect, it is effective by mixing a specific compound with ketene dimer. The inventors have found that a sizing composition can be obtained which has good dispersion stability even in a high component concentration range, has a good rise in size performance, and has an excellent size performance effect, and completed the present invention.

That is, the present invention is a water dispersion of a mixture of a ketene dimer represented by the following general formula (1) and an amide compound represented by the general formula (2) in a weight ratio of 99.8 / 0.2 to 80/20. It relates to a papermaking sizing composition characterized by comprising a dispersion.

(In the formula, R ₁ and R ₂ are an alkyl group, an alkenyl group or an aryl group having 8 to 24 carbon atoms.) (In the formula, R ₃ is an alkyl group or alkenyl group having 7 to 23 carbon atoms. R ₄ and R ₅ are hydrogen or an alkyl group or alkenyl group having 1 to 5 carbon atoms.) Ketene constituting the present invention As a dimer, JP-A-48-4870
2, JP-A-52-110906, JP-A-52-118010
Any of the known ketene dimers disclosed in JP-A Nos. 55-98997, 55-116898, 60-99097 and the like can be used.

In the present invention, the mixing ratio of the ketene dimer represented by the general formula (1) and the amide compound represented by the general formula (2) is important, and the weight stability thereof is greater than 99.8 / 0.2. Is significantly deteriorated, and when it is smaller than 80/20, a phenomenon such as a poor rising is observed, and the weight ratio must be within the range of 99.8 / 0.2 to 80/20.

To obtain the size composition of the present invention, first, the ketene dimer is melted at a temperature equal to or higher than its melting point, and the amide compound of the present invention is dissolved therein. Next, while maintaining the molten state of this mixture, it is mixed and dispersed in water which has been heated in advance. The temperature at the time of dispersion is desirably 100 ° C or lower, preferably 80 ° C or lower. At too high a temperature, the ketene dimer can react with water to give a reaction product that does not have a size effect.

In addition, an appropriate emulsifier or dispersant is required for this mixing and dispersion, and as this dispersant, known ketene dimer emulsifiers and dispersants can be used. That is, there are various nonionic, cationic and anionic surfactants and dispersants, and preferred examples thereof include the following compounds.

The nonionic surfactant or dispersant has 8 to 8 carbon atoms.
Polyethylene oxide adducts of 18 higher alcohols or fatty acids, polyethylene oxide adducts of alkylphenols such as octylphenol and nonylphenol (Oil Chemistry, Volume 10, No. 5, p. 282), and polypropylenes of these higher alcohols, fatty acids, alkylphenols Block or random adducts of oxides and polyethylene oxides (Japanese Patent Laid-Open No. 50-53608, Japanese Patent Publication No. 55-37639), non-ionic polymers such as polyvinyl alcohol and oxidized starch (Japanese Patent Laid-Open No. 55-132799). Gazette) and the like.

Examples of cationic dispersants include cationic starch and epihalohydrin-modified polyalkylene polyamides (JP-A-48-48702), polyethyleneimine, polyvinylpyridine, cationic polyurethane resins and the like (JP-A-55).
-132799), a cationic vinyl copolymer (Japanese Patent Laid-Open No.
60-99097, JP-A-60-104599, JP-A-60
-219245, JP-A-60-220137) and the like.

Examples of the anionic dispersant include sodium naphthalene sulfonate formaldehyde condensate and sodium lignin sulfonate (JP-A-55-116898).

Of these, cationic dispersants are most preferred. The amount of these emulsifiers and dispersants added is 5 to 70% by weight, preferably 10 to 40% by weight, based on the mixture of the ketene dimer and the amide compound. If the amount of the dispersant is smaller than this range, the stability of the sizing agent dispersion is poor, and if it is added in an excessively large amount, the sizing effect is reduced, which is not preferable.

In order to use the sizing agent of the present invention with good yield, it is effective to use a fixing agent, and a cationic polymer is preferable as the fixing agent. Preferred examples of the cationic polymer used as the fixing agent include cationized starch, cationized cellulose, polyamide-based polymer, polyethyleneimine, polyvinylpyridine and its quaternized product, polydimethylaminoethyl methacrylate and its quaternized product, and polydiethylamino. Examples thereof include ethyl methacrylate and its quaternary products, and copolymers of these cationic monomers and acrylamide.

In carrying out the present invention, the sizing composition of the present invention is added in an amount of 0.01 to 2% by weight, preferably 0.05 to 1% by weight, as a solid content based on the weight of pulp. It goes without saying that the addition level of these sizing agents is adjusted according to the sizing degree required by the target paper.

As described above, the sizing composition according to the present invention is used in the form of being dispersed in water, and the particle size of the sizing particles dispersed in water is 5 μm or less, preferably 1 μm or less. Is desirable. If the particle size is larger than 5 microns, the stability of the dispersion liquid may be impaired or the size effect may be deteriorated. A homomixer, an ultrasonic emulsifier, a high-pressure discharge homogenizer, or the like can be used to disperse the sizing particles.

〔The invention's effect〕

The sizing composition of the present invention has good dispersion stability, good rise of sizing performance, and excellent sizing performance effect.

〔Example〕

Hereinafter, the present invention will be described in detail with reference to Examples, but the present invention is not limited to these Examples.

Example 1 <Preparation of Sizing Agent Dispersion> Various ketene dimers and amide compounds shown in Table 1 were used in an amount of 70-80.
Melted and mixed at ℃, warm water containing various dispersants shown in Table 2 (70
-80 ° C) was added, the mixture was emulsified with a high-pressure discharge type submicron homogenizer at a pressure of 200 kg / cm ² , and further cooled to obtain a sizing composition.

The composition of the obtained sizing composition and the dispersant used are shown in Tables 1 and 2.
Shown in.

<Papermaking conditions> The papermaking used in this test was manufactured under the following conditions.

Pulp: LBKP (Canadian Standard Freeness 400
ml) Sizing agent: 0.1% solid content based on pulp weight Fixing agent: cationized starch (commercial item), solid content 0.2 to 0.8% based on pulp amount Retention agent: Cationic polyacrylamide polymer (commercial item) , Solid content 0.02% to pulp weight Filler: heavy calcium carbonate (commercial product) / talc (commercial product) [50 / 50wt%] Add to adjust the filler weight in the paper to 12% Fixer pH: 7.5 Order of addition: pulp-filler-fixer-size-retention improver Papermaking: tappy square hand machine Press: 3.5kgw / cm ² x 2 minutes Drying: rotary drum dryer, 100 ° C x 40 Basis weight per second: 70 g / m ² <Size test> The size test was performed by the following method.

Sizing test: Steckit method (JIS P-8122) Bend four sides of the test paper upward to form a boat, and float it on a 2% NH ₄ SCN aqueous solution. Simultaneously with the floating, a drop of 1% FeCl ₃ aqueous solution was dropped onto the test paper from above, and the time (seconds) until both the aqueous solutions penetrated into contact with the paper and three red spots of iron thiocyanate appeared were measured.

Table 3 shows the test results obtained by measuring the sizing degree of the paper made under the above conditions immediately after the paper making and after one day humidity control (20 ° C. × 60%).

The sizing degree immediately after the papermaking shows the quality of the rising of the size effect, and the higher the value, the better.

<Stability Test of Sizing Composition> The dispersion stability test of the sizing composition was conducted after leaving the sizing composition shown in Table 1 at 5 ° C., 20 ° C. and 40 ° C. for 1 month. The state of dispersion of the sizing agent was observed with the naked eye.

The evaluation of dispersion stability at 5 ° C, 20 ° C, and 40 ° C is indicated by ○, △, and ×, and the meanings are as follows.

◯: The emulsified state is almost the same as that at the beginning.

Δ: It is possible to use although it has a slightly thickening tendency.

X: The emulsion is thickened or gelled and cannot be used. Or it cannot be used due to creaming.

The results are shown in Table 3.

Claims (1)

[Claims] 1. A general formula (1) (In the formula, R ₁ and R ₂ are an alkyl group, an alkenyl group or an aryl group having 8 to 24 carbon atoms.), And a ketene dimer represented by the general formula (2) (In the formula, R ₃ is an alkyl group or an alkenyl group having 7 to 23 carbon atoms. R ₄ and R ₅ are hydrogen or an alkyl group or alkenyl group having 1 to 5 carbon atoms.) 1. A sizing composition for papermaking, which comprises a water dispersion prepared by dispersing a mixture having a weight ratio of 99.8 / 0.2 to 80/20 in water.