JP4813640B2 - Method for producing cellulose ether - Google Patents

Description

【００１９】
コットンリンターパルプを用いた実施例１と比較例１の結果、コットンパルプを用いた実施例２と比較例２の結果より、本実施例では、粉砕動力原単位が低減され、粉砕によるパルプ中のセルロースの重合度低下の軽減、すなわち高粘性のセルロースエーテルを得られた。
【００２０】
【発明の効果】
本発明の方法によれば、粉砕動力原単位が低減され、エネルギーを低下でき、粉砕によるパルプ中のセルロースの重合度低下が軽減し、すなわち高粘性のセルロースエーテルを得られる。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for producing a powdered pulp used for a raw material of cellulose ether and other industrial uses.
[0002]
[Prior art]
Powdered pulp is used for cellulose ether raw materials and other industrial purposes.
When trying to obtain a powdery pulp by pulverizing a sheet-like pulp, there has been no conventional technique that pays attention to the weight per unit area of the sheet-like pulp.
[0003]
[Problems to be solved by the present invention]
In the conventional technology, when the sheet pulp is pulverized, the pulverization power unit of the pulverizer is very large, and the degree of polymerization of cellulose, which is the main component of the pulp, is significantly reduced. The problem was that the viscosity of the aqueous solution of cellulose ether produced as a raw material was low.
An object of the present invention is to reduce the basic unit of pulverization power when pulverizing a sheet-like pulp to obtain a powdery pulp, and to reduce a decrease in the degree of polymerization of cellulose.
[0004]
[Means for Solving the Problems]
In order to solve the above-mentioned problems, the present invention controls the weight per area of the sheet-like pulp that is a pulverized raw material when the sheet-like pulp is pulverized to obtain a powdery pulp. Cotton linter pulp weight per surface area of 700~1200g / ^{m 2} pulp sheet, wood pulp using a sheet-like pulp 900~1200g / ^{m 2.}
[0005]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described in detail.
The cotton linter pulp of the present invention is a pulp obtained using fibers produced in cotton seeds as raw materials. The wood pulp of the present invention is a pulp obtained using wood as a raw material. The degree of polymerization of cellulose contained in cotton linter pulp and wood pulp is not limited, but usually those having a weight average degree of polymerization (hereinafter abbreviated as “Dpw”) by a viscosity measurement method of 500 to 8,000 are used.
[0006]
Pulp is classified into sheet pulp, powdered pulp, and cotton-like pulp based on its shape. The sheet-like pulp which is the object of the present invention is preferably a flat pulp having a thickness of 3 mm or less.
The manufacturing method of sheet pulp is not particularly limited.
[0007]
Sheet pulp usually contains about several to 10% by weight of water. The “weight per area” referred to in the present invention is a weight not including the weight of moisture. Although the weight per area apparently varies depending on the water content, the effect of the present invention is not affected if the water content is 10% by weight or less. That is, it is necessary to pay attention to the weight other than moisture.
The method for obtaining the weight per area excluding the weight of moisture is according to the following equation.
W = M × (1−0.01x) / S
Here, W is the weight per area excluding the weight of moisture, M is the weight of the sheet-like pulp with area S including moisture, and x is the moisture (% by weight) of this pulp. The moisture content of the pulp is measured by weight loss when 2 g of pulp pieces are dried at 105 ° C. for 1 hour or more.
[0008]
The area of the sheet-like pulp referred to in the present invention refers to the area of the largest surface among the six faces when a piece of sheet-like pulp is regarded as a hexahedron.
Cotton linter pulp used in the present invention, the weight per area of 650 g / m ² or more, preferably sheet-like pulp 700~1,200g / m ^2, wood pulp, 900 g / m ² or more, preferably from 900 to 1 , 200 g / m ² of sheet pulp. If it is smaller than that, the effect of the present invention, that is, the effect of reducing the power unit and the effect of reducing the polymerization degree may not be obtained.
The power unit is the required power of a pulp crusher for pulverizing a certain amount of sheet-like pulp to obtain a powdery pulp having a certain average particle diameter.
[0009]
The thickness and apparent density of the sheet-like pulp used in the present invention are not particularly limited, but usually those having a thickness of 0.5 to 2.5 mm and an apparent density of 0.4 to 1.0 g / ml are used. Since the weight per area can be expressed by the product of the thickness of the sheet and the apparent density, it is preferable to use a material having a larger apparent density if the thickness is constant and a material having a larger thickness if the apparent density is constant. Of course, the weight per area must satisfy 650 g / m ² or more for cotton linter pulp and 900 g / m ² or more for wood pulp.
[0010]
The sheet-like pulp used in the present invention can be made into an appropriate size and shape, for example, 0.5 to 2 cm square chips, which can be easily put into a pulverizer, according to the structure of the pulverizer before pulverization.
Examples of the pulverizer used in the pulverization of the present invention include a knife mill, an impact pulverizer, and a vertical roller mill, but are not particularly limited.
The average particle size of the powdered pulp obtained in the present invention is 1,000 μm or less, preferably 60 to 500 μm. When the average particle size exceeds 1,000 μm, the fluidity of the powdered pulp is lowered, and it may be difficult to handle as a powder.
[0011]
The cellulose ether of the present invention is prepared by a known method, for example, by adding an alkali cellulose such as sodium hydroxide or potassium hydroxide to powdered pulp, and then adding an etherifying agent such as methyl chloride, propylene oxide or ethylene oxide. Obtained by heating.
[0012]
【Example】
EXAMPLES Hereinafter, although an Example and a comparative example demonstrate this invention further in detail, this invention is not limited to description of these Examples.
Example 1
A sheet-like cotton linter pulp having a weight per area of 750 g / m ² and a Dpw of 7,000 according to a cadoxene solution viscosity measurement method was pulverized with a knife mill (HA-2542: manufactured by Horai Iron Works). The grinding power unit was 0.17 kwh / kg. The average particle diameter of the obtained powdery pulp was 250 μm, and Dpw was 4,770.
100 parts by weight of the pulverized pulp was put into a reactor equipped with an internal stirrer, and after sufficient nitrogen substitution, 123 parts by weight of sodium hydroxide, 80 parts by weight of methyl chloride for methoxyl group substitution, and for substitution of hydroxypropoxyl group Add 21 parts by weight of propylene oxide, react at 40-100 ° C., purify with hot water until the residual salt content is about 1% by weight, and then dry to contain 1.2% by weight of water. A raw material hydroxypropylmethylcellulose was obtained. This raw material hydroxypropylmethylcellulose had a methoxyl substitution degree of 1.4 and a hydroxypropoxyl group substitution degree of 0.2. The degree of substitution indicates the number of substituents introduced per glucose unit. The viscosity of the obtained 1% by weight aqueous solution of hydroxypropylmethylcellulose was 19,000 mPa · s.
[0013]
Example 3
The same operation as in Example 1 was performed except that a sheet-like cotton linter pulp having a weight per area of 1200 g / m ² was used. The pulverization power unit was 0.10 kwh / kg, the average particle size of the obtained powdered pulp was 250 μm, and Dpw was 4,850. The viscosity of a 1% by weight aqueous solution of hydroxypropylmethylcellulose was 19,500 mPa · s.
[0014]
Example 3
The same operation as in Example 1 was performed except that a sheet-like wood pulp having a weight per area of 950 g / m ² and a Dpw of 4,000 was used. The basic unit of pulverization power was 0.13 kwh / kg, the average particle size of the obtained powdered pulp was 120 μm, and Dpw was 3,060. The viscosity of a 1% by weight aqueous solution of hydroxypropylmethylcellulose was 8,000 mPa · s.
[0015]
Example 4
The same operation as in Example 1 was performed except that a sheet-like wood pulp having a weight per area of 1,200 g / m ² and a Dpw of 4,000 was used. The pulverization power basic unit was 0.10 kwh / kg, the average particle diameter of the obtained powdered pulp was 120 μm, and Dpw was 3,150. The viscosity of a 1% by weight aqueous solution of hydroxypropylmethylcellulose was 8,200 mPa · s.
[0016]
Comparative Example 1
The same operation as in Example 1 was performed except that a sheet-like cotton linter pulp having a weight per area of 570 g / m ² was used. The basic unit of pulverization power is 0.25 kwh / kg, the average particle size of the obtained powdered pulp is 250 μm, Dpw is 4,500, and the viscosity of a 1% by weight aqueous solution of hydroxypropylmethylcellulose is 15,000 mPa · s. It was.
[0017]
Comparative Example 2
The same operation as in Example 1 was performed except that a sheet-like wood pulp having a weight per area of 750 g / m ² was used. The basic unit of pulverization power is 0.17 kwh / kg, the average particle size of the obtained powdered pulp is 120 μm, Dpw is 2,390, and the viscosity of a 1 wt% aqueous solution of hydroxypropylmethylcellulose is 5,000 mPa · s. It was.
[0018]
The results are summarized in Table 1.
[Table 1]

[0019]
From the results of Example 1 and Comparative Example 1 using cotton linter pulp, and from the results of Example 2 and Comparative Example 2 using cotton pulp, in this example, the pulverization power basic unit is reduced, A reduction in the degree of polymerization of cellulose, that is, a highly viscous cellulose ether was obtained.
[0020]
【The invention's effect】
According to the method of the present invention, the basic unit of pulverization power can be reduced, energy can be reduced, and the decrease in the degree of polymerization of cellulose in the pulp due to pulverization can be reduced, that is, a highly viscous cellulose ether can be obtained.

Claims (2)

The thickness the weight per area at 3mm or less is obtained by pulverizing a pulp sheet is a cotton linters pulp is 700~1200g / m ² pulp powder, after the alkali cellulose by the addition of alkali, A method for producing cellulose ether, comprising adding an etherifying agent and heating. Alkali is added to powdery pulp obtained by pulverizing sheet pulp, which is a wood pulp having a thickness of 3 mm or less and a weight per area of 900 to 1200 g / m ² , and then etherified. A method for producing cellulose ether, comprising adding an agent and heating.