PROCESS FOR PRODUCING REFINED COTTON WITH HIGH POLYMERIZATION DEGREE

Abstract

A process for producing refined cotton with a high polymerization degree includes: a. selection of material; b. impurity removal; c. impregnation; d. pretreatment: compounding triethanolamine, sodium carbonate, copper sulfate and magnesium oxide in equal proportion to form a cooking compound adjuvant with a mass concentration of 0.2-0.5%, putting the cookingcompound adjuvant into a spherical digester together with the cotton linter subjected to the impregnation treatment, heating to 70 C, stopping heating, and subjecting to idling pretreatment for 40-60 min; e. cooking; f. cooling of the spherical digester; g. formulating a chlorine dioxide bleaching stabilization solution; h. a first stage of bleaching; I. alkali treatment; J. a second stage of bleaching; K. dechlorination; and 1. rolling and drying by baking.

Claims

1. A process for producing refined cotton with a high polymerization degree, comprising the following steps: material selection: selecting a cotton linter without impurities of three kinds of foreign fibers, wherein the cotton linter has a fiber length of 13-15 mm and a maturity of more than 80%; impurity removal: opening and scutching the cotton linter, and removing impurities of sand, stone and cotton hulls by an impurity remover; impregnation: blending a sodium hydroxide solution with a mass concentration of 1-2.5%, a surfactant with a mass concentration of 0.1-0.2%, a cyclic ketone compound with a mass concentration of 0.1-0.2%, sulfur trioxide with a mass concentration of 0.2-0.5% and hydrogen peroxide with a mass concentration of 30% to form a cooking agent, and uniformly spraying the cooking agent into the cotton linter at a liquid ratio of 1:2.5-4.0; pretreatment: compounding triethanolamine, sodium carbonate, copper sulfate and magnesium oxide in equal proportion to form a cooking compound adjuvant with a mass concentration of 0.2-0.5%, putting the cooking compound adjuvant into a spherical digester together with the cotton linter subjected to the impregnation treatment, heating to 70° C., stopping heating, and subjecting to idling pretreatment for 40-60 min; cooking; wherein, a first stage of temperature rise: uniformly raising the temperature of the spherical digester to 100-1 10° C. for a temperature rise time controlled within 30-40 min; a second stage of temperature rise: then uniformly raising the temperature of the spherical digester to 120-130° C. for a temperature rise time controlled within 20-30 min, and keeping at this temperature for 20 min; cooling of the spherical digester: quickly cooling the interior of the spherical digester by pouring condensed water at 10-15° C. into the spherical digester, so that the pressure in the spherical digester drops to zero within 8-15 min and the temperature drops below 60° C., opening a covering cap of the spherical digester to recover alkali liquor and pouring out cotton pulp, and putting the pulp into a container filled with water at a normal temperature for cooling; formulating a chlorine dioxide bleaching stabilization solution; wherein, (1) taking 75-90 parts of deionized water, 2-4 parts of aminoalcohol, 1-2 parts of polyaminoamide, 0.5-1.5 parts of polyvinylpyrrolidone, 0.5-1 part of ethylenediamine tetraacetic acid, 5-8 parts of phosphate and 2-3 parts of potassium hydrogen phthalate, mixing them at the aforementioned proportion of parts by weight, adding into a buffer tank and stirring for 15-60 min, and allowing to stand for 1-2 h to formulate a buffer absorption solution; (2) preheating a chlorate solution with a mass concentration of 30-40 % and a hydrochloric acid solution with a mass concentration of 30-40% to 50-65° C. respectively, and adding the chlorate solution and the hydrochloric acid solution dropwise into a reactor continuously according to a mass ratio of 1:0.8-1.5, to generate a mixed gas of chlorine and chlorine dioxide; (3) pumping the generated mixed gas of chlorine dioxide and chlorine into a buffer tank in a manner of negative pressure of 0.05-0.08 MPa, circulating for 30 min-60 min, and fully contacting the generated mixed gas with the circularly flowing buffer absorption solution, so that the mixed gas is completely absorbed by the buffer absorption solution to prepare a stable chlorine dioxide bleaching solution with a pH controlled at 7-8; and (4) sealing the formulated stable chlorine dioxide bleaching solution for storage at a temperature of 15-25° C.; a first stage of bleaching: washing the cooked cotton pulp with water for the first time, and conducting first bleaching of the cotton pulp with ethylenediamine tetraacetic acid with a mass concentration of 99.9% and a chlorine dioxide solution with a mass concentration of 1-2% for a time of 20-30 min, alkali treatment: washing the cotton pulp with water for the second time, filtering to dryness, controlling a pH value at 10-12, and performing alkali treatment with a sodium hydroxide solution with a mass concentration of 30% and a magnesium carbonate solution with a mass concentration of 0.02-0.5% for a time of 10-20 min; a second stage of bleaching: washing the cotton pulp with water for the third time, and conducting second bleaching with a chlorine dioxide solution with a mass concentration of 0.1 -0.2% for a bleaching time of 10-20 min, wherein 0.05-0.1% of sodium hypochlorite and 0.01-0.5% of amino hydroxy acid are added in the process of bleaching; dechlorination: washing the cotton pulp with water for the fourth time, conducting dechlorination treatment with a Na.sub.2S.sub.2O.sub.3 solution with a mass concentration of 25-30%, washing the cotton pulp with water for the fifth time, and controlling a pH value between 6.8 and 7.0; and rolling and drying by baking: rolling the bleached cotton pulp for dehydration, and finally drying by baking to obtain a finished product with a polymerization degree up to more than 2,800.

2. The process for producing refined cotton with a high polymerization degree according to claim 1, wherein in the process of impregnation, the sodium hydroxide solution is 2.5-4 parts, the surfactant is 0.001-0.003 parts, the cyclic ketone compound is 0.0005-0.002 parts, sulfur trioxide is 0.002-0.005 parts, and hydrogen peroxide is 0.002-0.005 parts.

3. The process for producing refined cotton with a high polymerization degree according to claim 1, wherein the cooking compound adjuvant is 0.005-0.01 part.

4. The process for producing refined cotton with a high polymerization degree according to claim 1, wherein the surfactant is ethylenediamine tetraacetic acid.

5. The process for producing refined cotton with a high polymerization degree according to claim 1, wherein the cyclic ketone compound is any one or more of naphthoquinone, anthraquinone or anthrone.

6. The process for producing refined cotton with a high polymerization degree according to claim 1, wherein the cyclic ketone compound is prepared by compounding naphthoquinone, anthraquinone and anthrone in equal proportion.

7. The process for producing refined cotton with a high polymerization degree according to claim 1, wherein the cotton linter is 1 part.

8. The process for producing refined cotton with a high polymerization degree according to claim 1, wherein in the process of the first stage of bleaching, ethylenediamine tetraacetic acid is 0.005-0.008 parts, and the chlorine dioxide solution is 2.5-4.5 parts.

9. The process for producing refined cotton with a high polymerization degree according to claim 1, wherein in the process of alkali treatment, the sodium hydroxide solution is 0.025-0.035 parts and the magnesium carbonate solution is 0.004-0.007 parts.

10. The process for producing refined cotton with a high polymerization degree according to claim 1, wherein in the process of the second stage of bleaching, the chlorine dioxide solution is 1.25-1.6 parts, sodium hypochlorite is 0.05-0.08 parts, and amino hydroxy acid is 0.005-0.008 parts; and in the process of dechlorination, Na.sub.2S.sub.2O.sub.3 is 0.003-0.006 part.

Description

DETAILED DESCRIPTION

[0045] The present invention is further described below with reference to embodiments.

Example 1

[0046] A process for producing refined cotton with a high polymerization degree, includes: [0047] a. material selection: selecting 4,000 Kg of a cotton linter without impurities of three kinds of yarns, wherein the cotton linter has a fiber length of 13-15 mm and a maturity of more than 80%; [0048] b. impurity removal: opening and scutching the cotton linter, and removing impurities such as sand, stone, cotton hulls and the like by an impurity remover; [0049] c. impregnation: blending 10,000 Kg of a sodium hydroxide solution with a mass concentration of 1%, 4 Kg of ethylenediamine tetraacetic acid with a mass concentration of 0.1%, 2 Kg of naphthoquinone with a mass concentration of 0.1%, 8 Kg of sulfur trioxide with a mass concentration of 0.2% and 8 Kg of hydrogen peroxide with a mass concentration of 30% to form a cooking agent, and uniformly spraying the cooking agent into the cotton linter at a liquid ratio of 1:2.5; [0050] d. pretreatment: compounding 5 Kg of triethanolamine, 5 Kg of sodium carbonate, 5 Kg of copper sulfate and 5 Kg of magnesium oxide to form a cooking compound adjuvant with a mass concentration of 0.2%, putting the cooking compound adjuvant into a spherical digester together with the cotton linter subjected to the impregnation treatment, heating to 70° C., stopping heating, and subjecting to idling pretreatment for 50 min; [0051] e. cooking: [0052] a first stage of temperature rise: uniformly raising the temperature of the spherical digester to 100-110° C. for a temperature rise time controlled at 35 min; [0053] a second stage of temperature rise: then uniformly raising the temperature of the spherical digester to 120-130° C. for a temperature rise time controlled at 25 min, and keeping at this temperature for 20 min; [0054] f. cooling of the spherical digester: quickly cooling the interior of the spherical digester by pouring condensed water at 10-15° C. into the spherical digester, so that the pressure in the spherical digester drops to zero within 10 min and the temperature drops below 60° C., opening a covering cap of the spherical digester to recover alkali liquor and pouring out cotton pulp, and putting the pulp into a container filled with water at a normal temperature for cooling; wherein by implementing with the aforementioned cooking process, the obtained cotton pulp was 3,000 Kg, and the obtained cooking polymerization degree was 2,968. [0055] g. formulating a chlorine dioxide bleaching stabilization solution: [0056] (1) taking 75 Kg of deionized water, 2 Kg of aminoalcohol, 1 Kg of polyaminoamide, 0.5 Kg of polyvinylpyrrolidone, 0.5 Kg of ethylenediamine tetraacetic acid, 5 Kg of phosphate and 2 Kg of potassium hydrogen phthalate, mixing them at the aforementioned weight ratio, adding into a buffer tank and stirring for 15 min, and allowing to stand for 1 h to formulate a buffer absorption solution; [0057] (2) firstly preheating a chlorate solution with a mass concentration of 30% to 50° C., and then preheating a hydrochloric acid solution with a mass concentration of 30% to 50° C., and then simultaneously adding the aforementioned chlorate solution and hydrochloric acid solution dropwise into a reactor continuously according to a mass ratio of 1:0.8, to generate a mixed gas of chlorine and chlorine dioxide, wherein the adding dropwise of the two ones were started at the same time and ended at the same time; [0058] (3) pumping the aforementioned generated mixed gas of chlorine dioxide and chlorine into a buffer tank in a manner of negative pressure of 0.08 MPa, circulating for 30 min, and fully contacting the generated mixed gas with the circularly flowing buffer absorption solution, so that the mixed gas is completely absorbed by the buffer absorption solution to prepare a stable chlorine dioxide bleaching solution with a pH controlled at 7; and [0059] (4) sealing the aforementioned formulated stable chlorine dioxide bleaching solution for storage at a temperature of 15° C.; [0060] h. a first stage of bleaching: washing the cooked cotton pulp with water for the first time, and conducting first bleaching of the cotton pulp with 15 Kg of ethylenediamine tetraacetic acid with a mass concentration of 99.9% and 7,500 Kg of a chlorine dioxide solution with a mass concentration of 1% for a time of 20 min; [0061] i. alkali treatment: washing the cotton pulp with water for the second time, filtering to dryness, controlling a pH value at 10, and performing alkali treatment with 75 Kg of a sodium hydroxide solution with a mass concentration of 30% and 12 Kg of a magnesium carbonate solution with a mass concentration of 0.02% for a time of 10 min; [0062] j. a second stage of bleaching: washing the cotton pulp with water for the third time, and conducting second bleaching with 3,750 Kg of a chlorine dioxide solution with a mass concentration of 0.1% for a bleaching time of 10 min, wherein 150 Kg of 0.05% of sodium hypochlorite and 15 Kg of 0.01% of amino hydroxy acid were added in the process of bleaching; [0063] k. dechlorination: washing the cotton pulp with water for the fourth time, conducting dechlorination treatment with 9 Kg of a Na.sub.2S.sub.2O.sub.3 solution with a mass concentration of 25%, washing the cotton pulp with water for the fifth time, and controlling a pH value at 6.8; and [0064] l. rolling and drying by baking: rolling the bleached cotton pulp for dehydration, and finally drying by baking to obtain a finished product with a polymerization degree of 2,884.

Example 2

[0065] A process for producing refined cotton with a high polymerization degree, includes: [0066] a. material selection: selecting 4,000 Kg of a cotton linter without impurities of three kinds of yarns, wherein the cotton linter has a fiber length of 13-15 mm and a maturity of more than 80%; [0067] b. impurity removal: opening and scutching the cotton linter, and removing impurities such as sand, stone, cotton hulls and the like by an impurity remover; [0068] c. impregnation: blending 12,000 Kg of a sodium hydroxide solution with a mass concentration of 2%, 6 Kg of ethylenediamine tetraacetic acid with a mass concentration of 0.15%, 6 Kg of anthraquinone with a mass concentration of 0.15%, 12 Kg of sulfur trioxide with a mass concentration of 0.4 % and 12 Kg of hydrogen peroxide with a mass concentration of 30% to form a cooking agent, and uniformly spraying the cooking agent into the cotton linter at a liquid ratio of 1:3; [0069] d. pretreatment: compounding 7.5 Kg of triethanolamine, 7.5 Kg of sodium carbonate, 7.5 Kg of copper sulfate and 7.5 Kg of magnesium oxide to form a cooking compound adjuvant with a mass concentration of 0.4%, putting the cooking compound adjuvant into a spherical digester together with the cotton linter subjected to the impregnation treatment, heating to 70° C., stopping heating, and subjecting to idling pretreatment for 40 min; [0070] e. cooking: [0071] a first stage of temperature rise: uniformly raising the temperature of the spherical digester to 100-110° C. for a temperature rise time controlled at 30 min; [0072] a second stage of temperature rise: then uniformly raising the temperature of the spherical digester to 120-130° C. for a temperature rise time controlled at 20 min, and keeping at this temperature for 20 min; [0073] f. cooling of the spherical digester: quickly cooling the interior of the spherical digester by pouring condensed water at 10-15° C. into the spherical digester, so that the pressure in the spherical digester drops to zero within 8 min and the temperature drops below 60° C., opening a covering cap of the spherical digester to recover alkali liquor and pouring out cotton pulp, and putting the pulp into a container filled with water at a normal temperature for cooling; [0074] wherein by implementing with the present cooking process, the obtained cotton pulp was 3,000.00 Kg, and the obtained cooking polymerization degree was 3,034. [0075] g. formulating a chlorine dioxide bleaching stabilization solution: [0076] (1) taking 90 Kg of deionized water, 4 Kg of aminoalcohol, 2 Kg of polyaminoamide, 1.5 Kg of polyvinylpyrrolidone, 1 Kg of ethylenediamine tetraacetic acid, 8 Kg of phosphate and 3 Kg of potassium hydrogen phthalate, mixing them at the aforementioned weight ratio, adding into a buffer tank and stirring for 60 min, and allowing to stand for 2 h to formulate a buffer absorption solution; [0077] (2) firstly preheating a chlorate solution with a mass concentration of 40% to 65° C., and then preheating a hydrochloric acid solution with a mass concentration of 35% to 65° C., and then simultaneously adding the aforementioned chlorate solution and hydrochloric acid solution dropwise into a reactor continuously according to a mass ratio of 1: 1.5, to generate a mixed gas of chlorine and chlorine dioxide, wherein the adding dropwise of the two ones were started at the same time and ended at the same time; [0078] (3) pumping the aforementioned generated mixed gas of chlorine dioxide and chlorine into a buffer tank in a manner of negative pressure of 0.05 MPa, circulating for 60 min, and fully contacting the generated mixed gas with the circularly flowing buffer absorption solution, so that the mixed gas is completely absorbed by the buffer absorption solution to prepare a stable chlorine dioxide bleaching solution with a pH controlled at 8; and [0079] (4) sealing the aforementioned formulated stable chlorine dioxide bleaching solution for storage at a temperature of 25° C.; [0080] h. a first stage of bleaching: washing the cooked cotton pulp with water for the first time, and conducting first bleaching of the cotton pulp with 20 Kg of ethylenediamine tetraacetic acid with a mass concentration of 99.9% and 11,000 Kg of a chlorine dioxide solution with a mass concentration of 1.5% for a time of 26 min; [0081] i. alkali treatment: washing the cotton pulp with water for the second time, filtering to dryness, controlling a pH value at 11, and performing alkali treatment with 90 Kg of a sodium hydroxide solution with a mass concentration of 30% and 16 Kg of a magnesium carbonate solution with a mass concentration of 0.2% for a time of 14 min; [0082] j. a second stage of bleaching: washing the cotton pulp with water for the third time, and conducting second bleaching with 4,200 Kg of a chlorine dioxide solution with a mass concentration of 0.15% for a bleaching time of 17 min, wherein 190 Kg of 0.06% of sodium hypochlorite and 20 Kg of 0.2% of amino hydroxy acid were added in the process of bleaching; [0083] k. dechlorination: washing the cotton pulp with water for the fourth time, conducting dechlorination treatment with 16 Kg of a Na.sub.2S.sub.2O.sub.3 solution with a mass concentration of 27%, washing the cotton pulp with water for the fifth time, and controlling a pH value at 6.9; and [0084] l. rolling and drying by baking: rolling the bleached cotton pulp for dehydration, and finally drying by baking to obtain a finished product with a polymerization degree of 2,957.

Example 3

[0085] A process for producing refined cotton with a high polymerization degree, includes: [0086] a. material selection: selecting 4,000 Kg of a cotton linter without impurities of three kinds of yarns, wherein the cotton linter has a fiber length of 13-15 mm and a maturity of more than 80%; [0087] b. impurity removal: opening and scutching the cotton linter, and removing impurities such as sand, stone, cotton hulls and the like by an impurity remover; [0088] c. impregnation: blending 16,000 Kg of a sodium hydroxide solution with a mass concentration of 2.5%, 9.2 Kg of ethylenediamine tetraacetic acid with a mass concentration of 0.2%, 8 Kg of anthrone with a mass concentration of 0.2%, 20 Kg of sulfur trioxide with a mass concentration of 0.5% and 20 Kg of hydrogen peroxide with a mass concentration of 30% to form a cooking agent, and uniformly spraying the cooking agent into the cotton linter at a liquid ratio of 1:4; [0089] d. pretreatment: compounding 10 Kg of triethanolamine, 10 Kg of sodium carbonate, 10 Kg of copper sulfate and 10 Kg of magnesium oxide to form a cooking compound adjuvant with a mass concentration of 0.5%, putting the cooking compound adjuvant into a spherical digester together with the cotton linter subjected to the impregnation treatment, heating to 70° C., stopping heating, and subjecting to idling pretreatment for 60 min; [0090] e. cooking: [0091] a first stage of temperature rise: uniformly raising the temperature of the spherical digester to 100-110° C. for a temperature rise time controlled at 40 min; [0092] a second stage of temperature rise: then uniformly raising the temperature of the spherical digester to 120-130° C. for a temperature rise time controlled at 30 min, and keeping at this temperature for 20 min; [0093] f. cooling of the spherical digester: quickly cooling the interior of the spherical digester by pouring condensed water at 10-15° C. into the spherical digester, so that the pressure in the spherical digester drops to zero within 15 min and the temperature drops below 60° C., opening a covering cap of the spherical digester to recover alkali liquor and pouring out cotton pulp, and putting the pulp into a container filled with water at a normal temperature for cooling; wherein by implementing with the present cooking process, the obtained cotton pulp was 3,000 Kg, and the obtained cooking polymerization degree was 2,907. [0094] g. formulating a chlorine dioxide bleaching stabilization solution: [0095] (1) taking 83 Kg of deionized water, 3.2 Kg of aminoalcohol, 1.6 Kg of polyaminoamide, 1.2 Kg of polyvinylpyrrolidone, 0.7 Kg of ethylenediamine tetraacetic acid, 7.3 Kg of phosphate and 2.4 Kg of potassium hydrogen phthalate, mixing them at the aforementioned weight ratio, adding into a buffer tank and stirring for 35 min, and allowing to stand for 1.5 h to formulate a buffer absorption solution; [0096] (2)firstly preheating a chlorate solution with a mass concentration of 36% to 62° C., and then preheating a hydrochloric acid solution with a mass concentration of 40% to 60° C., and then simultaneously adding the aforementioned chlorate solution and hydrochloric acid solution dropwise into a reactor continuously according to a mass ratio of 1:1.2, to generate a mixed gas of chlorine and chlorine dioxide, wherein the adding dropwise of the two ones were started at the same time and ended at the same time; [0097] (3) pumping the aforementioned generated mixed gas of chlorine dioxide and chlorine into a buffer tank in a manner of negative pressure of 0.065 MPa, circulating for 50 min, and fully contacting the generated mixed gas with the circularly flowing buffer absorption solution, so that the mixed gas is completely absorbed by the buffer absorption solution to prepare a stable chlorine dioxide bleaching solution with a pH controlled at 7.5; and [0098] (4) sealing the aforementioned formulated stable chlorine dioxide bleaching solution for storage at a temperature of 20° C.; [0099] h. a first stage of bleaching: washing the cooked cotton pulp with water for the first time, and conducting first bleaching of the cotton pulp with 24 Kg of ethylenediamine tetraacetic acid with a mass concentration of 99.9% and 13,500 Kg of a chlorine dioxide solution with a mass concentration of 2% for a time of 30 min; [0100] i. alkali treatment: washing the cotton pulp with water for the second time, filtering to dryness, controlling a pH value at 12, and performing alkali treatment with 105 Kg of a sodium hydroxide solution with a mass concentration of 30% and 21 Kg of a magnesium carbonate solution with a mass concentration of 0.5% for a time of 20 min; [0101] j. a second stage of bleaching: washing the cotton pulp with water for the third time, and conducting second bleaching with 4,800 Kg of a chlorine dioxide solution with a mass concentration of 0.2% for a bleaching time of 20 min, wherein 240 Kg of 0.1% of sodium hypochlorite and 24 Kg of 0.5% of amino hydroxy acid were added in the process of bleaching; [0102] k. dechlorination: washing the cotton pulp with water for the fourth time, conducting dechlorination treatment with 18 Kg of a Na.sub.2S.sub.2O.sub.3 solution with a mass concentration of 30%, washing the cotton pulp with water for the fifth time, and controlling a pH value at 7.0; and [0103] l. rolling and drying by baking: rolling the bleached cotton pulp for dehydration, and finally drying by baking to obtain a finished product with a polymerization degree of 2,819.

Example 4

[0104] A process for producing refined cotton with a high polymerization degree, includes: [0105] a. material selection: selecting 4,000 Kg of a cotton linter without impurities of three kinds of yarns, wherein the cotton linter has a fiber length of 13-15 mm and a maturity of more than 80%; [0106] b. impurity removal: opening and scutching the cotton linter, and removing impurities such as sand, stone, cotton hulls and the like by an impurity remover; [0107] c. impregnation: blending 16,000 Kg of a sodium hydroxide solution with a mass concentration of 2%, 8 Kg of ethylenediamine tetraacetic acid with a mass concentration of 0.12%, a cyclic ketone compound with a mass concentration of 0.16%, 11 Kg of sulfur trioxide with a mass concentration of 0.4% and 10 Kg of hydrogen peroxide with a mass concentration of 30% to form a cooking agent, and uniformly spraying the cooking agent into the cotton linter at a liquid ratio of 1:3, wherein the cyclic ketone compound consisted of 1 Kg of naphthoquinone, 1 Kg of anthraquinone and 1 Kg of anthrone; [0108] d. pretreatment: compounding 7.5 Kg of triethanolamine, 7.5 Kg of sodium carbonate, 7.5 Kg of copper sulfate and 7.5 Kg of magnesium oxide in equal proportion to form a cooking compound adjuvant with a mass concentration of 0.35%, putting the cooking compound adjuvant into a spherical digester according to proportion has together with the cotton linter subjected to the impregnation treatment, heating to 70° C., stopping heating, and subjecting to idling pretreatment for 55 min; [0109] e. cooking: [0110] a first stage of temperature rise: uniformly raising the temperature of the spherical digester to 100-110° C. for a temperature rise time controlled at 30 min; [0111] a second stage of temperature rise: then uniformly raising the temperature of the spherical digester to 120-130° C. for a temperature rise time controlled at 20 min, and keeping at this temperature for 20 min; [0112] f. cooling of the spherical digester: quickly cooling the interior of the spherical digester by pouring condensed water at 10-25° C. into the spherical digester, so that the pressure in the spherical digester drops to zero within 12 min and the temperature drops below 60° C., opening a covering cap of the spherical digester to recover alkali liquor and pouring out cotton pulp, and putting the pulp into a container filled with water at a normal temperature for cooling; wherein by implementing with the present cooking process, the obtained cotton pulp was 3,000 Kg, and the obtained cooking polymerization degree was 2,945. [0113] g. formulating a chlorine dioxide bleaching stabilization solution: [0114] (1) taking 83 Kg of deionized water, 3.2 Kg of aminoalcohol, 1.6 Kg of polyaminoamide, 1.2 Kg of polyvinylpyrrolidone, 0.7 Kg of ethylenediamine tetraacetic acid, 7.3 Kg of phosphate and 2.4 Kg of potassium hydrogen phthalate, mixing them at the aforementioned weight ratio, adding into a buffer tank and stirring for 35 min, and allowing to stand for 1.5 h to formulate a buffer absorption solution; [0115] (2) firstly preheating a chlorate solution with a mass concentration of 36% to 62° C., and then preheating a hydrochloric acid solution with a mass concentration of 40% to 60° C., and then simultaneously adding the aforementioned chlorate solution and hydrochloric acid solution dropwise into a reactor continuously according to a mass ratio of 1:1.2, to generate a mixed gas of chlorine and chlorine dioxide, wherein the adding dropwise of the two ones were started at the same time and ended at the same time; [0116] (3) pumping the aforementioned generated mixed gas of chlorine dioxide and chlorine into a buffer tank in a manner of negative pressure of 0.065 MPa, circulating for 50 min, and fully contacting the generated mixed gas with the circularly flowing buffer absorption solution, so that the mixed gas is completely absorbed by the buffer absorption solution to prepare a stable chlorine dioxide bleaching solution with a pH controlled at 7.5; and [0117] (4) sealing the aforementioned formulated stable chlorine dioxide bleaching solution for storage at a temperature of 20° C.; [0118] h. a first stage of bleaching: washing the cooked cotton pulp with water for the first time, and conducting first bleaching of the cotton pulp with 17 Kg of ethylenediamine tetraacetic acid with a mass concentration of 99.9% and 9,500 Kg of a chlorine dioxide solution with a mass concentration of 1.6% for a time of 22 min; [0119] i. alkali treatment: washing the cotton pulp with water for the second time, filtering to dryness, controlling a pH value at 11, and performing alkali treatment with 85 Kg of a sodium hydroxide solution with a mass concentration of 30% and 14 Kg of a magnesium carbonate solution with a mass concentration of 0.3% for a time of 106 min; [0120] j. a second stage of bleaching: washing the cotton pulp with water for the third time, and conducting second bleaching with 3,950 Kg of a chlorine dioxide solution with a mass concentration of 0.13% for a bleaching time of 17 min, wherein 190 Kg of 0.08% of sodium hypochlorite and 17 Kg of 0.09% of amino hydroxy acid were added in the process of bleaching; [0121] k. dechlorination: washing the cotton pulp with water for the fourth time, conducting dechlorination treatment with 14 Kg of a Na.sub.2S.sub.2O.sub.3 solution with a mass concentration of 26%, washing the cotton pulp with water for the fifth time, and controlling a pH value at 6.9; and [0122] l. rolling and drying by baking: rolling the bleached cotton pulp for dehydration, and finally drying by baking to obtain a finished product with a polymerization degree of 2,896.

Example 5

[0123] A process for producing refined cotton with a high polymerization degree, includes: [0124] a. material selection: selecting 4,000 Kg of a cotton linter without impurities of three kinds of yarns, wherein the cotton linter has a fiber length of 13-15 mm and a maturity of more than 80%; [0125] b. impurity removal: opening and scutching the cotton linter, and removing impurities such as sand, stone, cotton hulls and the like by an impurity remover; [0126] c. impregnation: blending 12,000 Kg of a sodium hydroxide solution with a mass concentration of 2.1%, 7 Kg of ethylenediamine tetraacetic acid with a mass concentration of 0.13%, a cyclic ketone compound with a mass concentration of 0.15%, 11 Kg of sulfur trioxide with a mass concentration of 0.3% and 9 Kg of hydrogen peroxide with a mass concentration of 30% to form a cooking agent, and uniformly spraying the cooking agent into the cotton linter at a liquid ratio of 1:3, wherein the cyclic ketone compound is composed of 1 Kg of naphthoquinone, 1 Kg of anthraquinone and 1 Kg of anthrone; [0127] d. pretreatment: compounding 10 Kg of triethanolamine, 10 Kg of sodium carbonate, 10 Kg of copper sulfate and 10 Kg of magnesium oxide to form a cooking compound adjuvant with a mass concentration of 0.4%, putting the cooking compound adjuvant into a spherical digester together with the cotton linter subjected to the impregnation treatment, heating to 70° C., stopping heating, and subjecting to idling pretreatment for 50 min; [0128] e. cooking: [0129] a first stage of temperature rise: uniformly raising the temperature of the spherical digester to 100-110° C. for a temperature rise time controlled at 40 min; [0130] a second stage of temperature rise: then uniformly raising the temperature of the spherical digester to 120-130° C. for a temperature rise time controlled at 30 min, and keeping at this temperature for 20 min; [0131] f. cooling of the spherical digester: quickly cooling the interior of the spherical digester by pouring condensed water at 10-15° C. into the spherical digester, so that the pressure in the spherical digester drops to zero within 10 min and the temperature drops below 60° C., opening a covering cap of the spherical digester to recover alkali liquor and pouring out cotton pulp, and putting the pulp into a container filled with water at a normal temperature for cooling; wherein by implementing with the present cooking process, the obtained cotton pulp was 3,000 Kg, and the obtained cooking polymerization degree was 2,936. [0132] g. formulating a chlorine dioxide bleaching stabilization solution: [0133] (1) taking 83 Kg of deionized water, 3.2 Kg of aminoalcohol, 1.6 Kg of polyaminoamide, 1.2 Kg of polyvinylpyrrolidone, 0.7 Kg of ethylenediamine tetraacetic acid, 7.3 Kg of phosphate and 2.4 Kg of potassium hydrogen phthalate, mixing them at the aforementioned weight ratio, adding into a buffer tank and stirring for 35 min, and allowing to stand for 1.5 h to formulate a buffer absorption solution; [0134] (2)firstly preheating a chlorate solution with a mass concentration of 36% to 62° C., and then preheating a hydrochloric acid solution with a mass concentration of 40% to 60° C., and then simultaneously adding the aforementioned chlorate solution and hydrochloric acid solution dropwise into a reactor continuously according to a mass ratio of 1:1.2, to generate a mixed gas of chlorine and chlorine dioxide, wherein the adding dropwise of the two ones were started at the same time and ended at the same time; [0135] (3) pumping the aforementioned generated mixed gas of chlorine dioxide and chlorine into a buffer tank in a manner of negative pressure of 0.065 MPa, circulating for 50 min, and fully contacting the generated mixed gas with the circularly flowing buffer absorption solution, so that the mixed gas is completely absorbed by the buffer absorption solution to prepare a stable chlorine dioxide bleaching solution with a pH controlled at 7.5; and [0136] (4) sealing the aforementioned formulated stable chlorine dioxide bleaching solution for storage at a temperature of 20° C.; [0137] h. a first stage of bleaching: washing the cooked cotton pulp with water for the first time, and conducting first bleaching of the cotton pulp with 22 Kg of ethylenediamine tetraacetic acid with a mass concentration of 99.9% and 11,300 Kg of a chlorine dioxide solution with a mass concentration of 1.8% for a time of 28 min; [0138] i. alkali treatment: washing the cotton pulp with water for the second time, filtering to dryness, controlling a pH value at 11, and performing alkali treatment with 93 Kg of a sodium hydroxide solution with a mass concentration of 30% and 18 Kg of a magnesium carbonate solution with a mass concentration of 0.45% for a time of 106 min; [0139] j. a second stage of bleaching: washing the cotton pulp with water for the third time, and conducting second bleaching with 4,300 Kg of a chlorine dioxide solution with a mass concentration of 0.18% for a bleaching time of 14 min, wherein 220 Kg of 0.09% of sodium hypochlorite and 22 Kg of 0.3% of amino hydroxy acid were added in the process of bleaching; [0140] k. dechlorination: washing the cotton pulp with water for the fourth time, conducting dechlorination treatment with 17 Kg of a Na.sub.2S.sub.2O.sub.3 solution with a mass concentration of 28%, washing the cotton pulp with water for the fifth time, and controlling a pH value at 6.9; and [0141] l. rolling and drying by baking: rolling the bleached cotton pulp for dehydration, and finally drying by baking to obtain a finished product with a polymerization degree of 2,881.

[0142] The above is only the preferred embodiments of the present invention, and does not restrict the present invention in any form. Although the present invention has been disclosed in the preferred embodiments, it is not intended to limit the present invention. Some changes or modifications into equivalent embodiments can be made by those of skills in the art by utilizing the technical content disclosed above without departing from the scope of the technical solution of the present invention, but any simple modifications, equivalent changes and modifications made to the aforementioned embodiments according to the technical essence of the present invention without departing from the content of the technical solution of the present invention are still within the scope of the technical solution of the present invention.