JPH1112979A - Readily disaggregatable internally added paper strength enhancing agent and production of readily disaggregatable paper or fibrous sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To produce a paper or a fibrous sheet, having strength enhancing effects at the time of drying, excellent in reaggregating properties and useful as a sanitary paper, fibrous mat, etc., by adding a specific cationized starch to a fiber raw material and forming the paper or fibrous sheet. SOLUTION: A cationized starch modified with an enzyme such as an α-amylase is added to a fiber raw material such as wood pulp fibers or synthetic fibers so as to provide 5-500 cP, preferably 10-200 cP viscosity of an aqueous solution with 15% solid content at 25 deg.C to form a paper or a fibrous sheet. Thereby, the objective readily disaggregatable paper or sheet is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an internally added paper strength enhancer containing an enzyme-modified cationized starch as an active ingredient, and a method for producing easily disintegrated paper or fiber sheet using the paper strength enhancer.

[0002]

2. Description of the Related Art Conventionally, in the papermaking industry, a dry paper strength enhancer has been used in order to improve various strengths when paper is dried. Water-soluble polymer compounds such as cationized starch, cationized or anionized polyacrylamide are examples.

[0003]

The paper made using the conventional dry strength agent generally does not disperse the paper, although to a lesser extent than the paper using the wet strength agent. In addition, the use of paper requiring re-dispersibility, such as toilet paper and sanitary paper, and agricultural paper and fiber mats that need to be immediately disaggregated by rainwater, is limited.

[0004] Further, in recent years when paper recycling is called out due to environmental problems, there is a demand for paper that does not consume energy when paper is defibrated. As the recycling rate of recycled paper increases, the general strength of paper decreases, and the use of dry strength agents is increasing, so a paper strength agent with good re-disintegration properties is particularly required. Have been.

[0005]

In order to solve the above problems, the present invention uses a cationized starch whose viscosity has been reduced to a specific viscosity by enzymatic modification as a paper strength agent. By using the enzyme-modified cationized starch as a paper-strength enhancer, excellent dry paper-strength can be obtained and, at the same time, excellent re-disintegration can be obtained.

[0006]

DETAILED DESCRIPTION OF THE INVENTION According to the present invention, a cationized starch is denatured with an enzyme and the viscosity of a 15% solids aqueous solution at 25 ° C. is 5 to 500 cps, preferably 10 to 200 cps.
And a method for producing a paper or fiber sheet that can be easily disintegrated using the paper strength enhancer.

The cationized starch used in the present invention includes starch obtained from various plants such as potatoes, sweet potatoes, tapioca and the like, starch obtained from grains such as wheat, rice, corn and the like or derivatives thereof. It is obtained by reacting with a cationizing agent, for example, 3-chloro-hydroxypropyl-trimethylammonium chloride or glycidyltrimethylammonium chloride in the presence of a catalyst. The amylolytic enzymes used in the present invention include α-amylase, β-amylase, γ-amylase, and iso-amylase produced by various bacteria, yeasts, animals and plants.
Although there are amylase and the like, α-amylase is most preferable in that it does not generate excessive low molecular weight substances, monosaccharides and oligosaccharides.

The low-viscosity cationic starch in the present invention is obtained by modifying the above-mentioned cationic starches with a starch-degrading enzyme to reduce the viscosity. However, unmodified raw starch or mild starch such as acetylated or phosphorylated ester is used. A low-viscosity cationic starch obtained by reacting the above-mentioned cationizing reagent with a low-viscosity starch obtained by reacting an enzyme with a low-viscosity starch is an embodiment of the present invention.

As a method for lowering the viscosity of starch, there are various oxidative methods other than enzymatic denaturation, for example, a method of cutting molecules with an oxidizing agent such as sodium hypochlorite or ammonium persulfate to lower the viscosity. It is not preferable because the paper strength enhancing effect is greatly reduced as compared with the original starch.

The paper strength enhancer of the present invention comprises a cationized starch which is enzyme-modified so that the viscosity of a 15% solids aqueous solution at 25 ° C. becomes 5 cps to 500 cps, preferably 10 cps to 200 cps. When it exceeds 500 cps, the disintegration of the used paper or fiber sheet becomes significantly inferior to that of no addition,
When the pressure is 5 cps or less, the effect of enhancing the paper strength is almost nil.

The paper strength enhancer of the present invention is added to an aqueous slurry of a fiber raw material such as wood pulp fiber, synthetic fiber and mineral fiber dispersed in water at a position called a so-called wet end in a papermaking process. It efficiently fixes to the fiber raw material and gives the paper, fiber sheet, fiber mat, etc., which have been made excellent, various strengths at the time of drying and at the same time imparts the property of being easily defibrated.

[0012]

The present invention will be specifically described below with reference to examples and comparative examples. In each of the following examples, unless otherwise specified, “%” means “% by weight” and “part” means “part by weight”.

[0013]

EXAMPLE 1 0.02% of α-amylase was added to a 20% aqueous dispersion of cationized starch as a potato raw material having a substitution rate (DS) of 0.03 with respect to the weight of the starch, and the mixture was stirred for 80 minutes.
The mixture was heated to a temperature of about 85 ° C. and decomposed for 10 minutes, and then diluted sulfuric acid was added to adjust the pH of the solution to 3.5 to 4.0.
After heating to 00 ° C for 10 minutes, the mixture was cooled and diluted with water to obtain an enzyme-modified cationized starch solution having a solid content of 15% and a viscosity of 75 cps at 25 ° C.

[0014]

Example 2 α-amylase was added to starch in an amount of 0.005
Except for using%, an enzyme-modified cationized starch solution having a solid content concentration of 15% and a viscosity at 25 ° C. of 450 cps was obtained in the same manner as in Example 1.

[0015]

Example 3 The same operation as in Example 3 was carried out except that cationized starch as a raw material of tapioca having a substitution rate (DS) of 0.035 was used, and α-amylase was used in an amount of 0.015% based on the starch. , A viscosity of 1 at a solid content of 15% at 25 ° C.
An enzyme-modified cationized starch solution having 90 cps was obtained.

[0016]

Example 4 α-amylase was added to starch at 0.05%
Except for using the same procedure as in Example 3, an enzyme-modified cationized starch solution having a solid content of 15% and a viscosity at 25 ° C of 19 cps was obtained.

[0017]

Example 5 The same procedure as in Example 3 was carried out except that α-amylase was used in an amount of 0.1% with respect to starch to obtain a solid content of 15%.
A solution was obtained of an enzyme-modified cationized starch having a viscosity of 8 cps at 25 ° C. in%.

[0018]

Example 6 A dispersion obtained by dispersing 25 parts of a starch as a raw material of tapioca in 75 parts of water was added with 0.03% α of the starch weight.
Amylase is added and mixed, and the mixture is decomposed by enzymatic reaction at 80 to 85 ° C. for 10 minutes.
After the H was adjusted to 3.5 to 4.0, the mixture was heated to 96 to 100 ° C for 10 minutes, cooled, and caustic soda was added at 50 ° C to 0.4.
Parts, glycidyltrimethylonmonium chloride (1.1 parts) was added, and the mixture was reacted at 45 to 50 ° C. for 8 hours, cooled, neutralized with sulfuric acid, and then diluted with water to obtain a solid content of 15%.
An aqueous solution of enzyme-modified cationized starch (DS0.05) having a viscosity of 40 cps at 25 ° C. was obtained.

[0019]

Example 7 α-amylase was 0.15% based on starch
Except for using the same procedure as in Example 3, an aqueous solution of an enzyme-modified cationic starch having a viscosity of 4.5 cps at 25 ° C of a 15% solid content solution was obtained.

[0020]

Comparative Example 1 α-amylase was added to starch in an amount of 0.004
The same procedure as in Example 1 was carried out, except for using%, to obtain an aqueous solution of a 15% solution of an enzyme-modified cationized starch having a viscosity of 620 cps at 25 ° C.

[0021]

Example 8 A 1% pulp slurry of bleached kraft pulp (L-BKP) beaten to 400 cc of Canadian freeness was coated with the paper strength enhancers described in Examples 1 to 6, Comparative Examples 1 and 2, and Table 1, respectively. Air dried pulp weight solids 1.0
%, And a conventional hand-made sheet was prepared using a TAPPI standard sheet machine. The obtained wet paper is 11
Dried for 2 minutes with a plate dryer at 0 ° C, 60g /
to obtain a handsheet paper corresponding to m ^2. The hand-made paper was subjected to humidity control in a room at 20 ° C. and a relative humidity of 65% for 24 hours, and then tested for paper strength and disintegration during drying. The test results are shown in Table 1. Table 1 Note * Viscosity: Viscosity ** defibration tests in B-type viscometer 25 ° C.: 2 pieces of paper 0.6g was split into 1 cm ²
Put into 00 cc of water, stir at 300 rpm using a stirrer, and measure the time until the paper piece is completely disintegrated. Cationized starch A: Cationized starch of tapioca raw material having DS 0.04 Cationized starch B: Cationized potato starch having DS 0.03, which is decomposed with sodium hypochlorite to reduce the viscosity Cationized starch C: Potato starch having a DS of 0.03 added with ammonium persulfate and thermally decomposed to lower viscosity

[0022]

[Table 1]

[0023]

According to the present invention, as shown in the above-mentioned embodiments, an excellent paper-strengthening effect at the time of drying and at the same time, an excellent disintegration property are imparted to the paper.

Claims (4)

[Claims] 1. An internal paper-strengthening agent comprising, as an active ingredient, a cationized starch which is enzyme-modified so that the aqueous solution having a solid content of 15% at 25 ° C. has a viscosity of 5 to 500 cps. 2. A paper or fiber which is easily disintegrated, wherein a cationized starch which is enzyme-modified so that the viscosity of a 15% solid content aqueous solution at 25 ° C. becomes 5 to 500 cps is added to a fiber raw material to form a paper. Sheet manufacturing method. 3. The viscosity of a 15% aqueous solid solution at 25 ° C. is 10 to 200 cps.
The internal paper strength enhancer according to the above. 4. An easily disintegrated fiber according to claim 2, wherein an enzymatically decomposed cationized starch having a viscosity at 25 ° C. of a 15% solid content aqueous solution at 25 ° C. of 10 to 200 cps is added to the fiber raw material. A method for producing paper or fiber sheets.