Method for preparing high-whiteness chemical pulp and paper products thereof by using corn stalk

A manufacturing method and technology of corn stalks, applied in pulping with inorganic alkali, pulp beating method, chemical/chemical mechanical pulping, etc., can solve the problems of difficult removal of metal ions and colored substances, yellowing of pulp, and difficult bleaching of pulp, etc. question

Inactive Publication Date: 2008-07-23

TIANJIN HUAJUN SCI & TECH

6 Cites 14 Cited by

AI-Extracted Technical Summary

Problems solved by technology

The disadvantages of this pulping method are: the raw materials used are limited to the raw materials of depilled corn stalks; the pulp obtained by cooking with ammonium method is not easy to be bleached; EOT When bleaching, due to the high amount of alkali used (6% to 10%), although this is beneficial to delignification, it will also...

Abstract

The invention discloses a preparation method of chemical pulp with high whiteness by corn stalks and paper product, wherein steaming adopts soda cooking by adding anthraquinones and surface-active material; bleaching adopts totally-chlorine-free bleaching of short program of OPAPO in the pulp making processes, wherein OP segment is oxygenic delignification segment reinforced by small amount of hydrogen peroxide; A segment is acid treatment segment; PO> is oxygen-reinforced hydrogen peroxide bleaching segment. The preparation method of chemical pulp with high whiteness by corn stalks and paper product has the advantages of less steaming time, high steaming and bleaching efficiency, free of chlorine and chlorine compounds while bleaching, high whiteness and strength of the paper pulp, energy saving, water saving, low production cost, and favorableness to environmental protection. In addition, with whiteness rate of above 85% ISO, the paper pulp made from corn stalks is able to be made into high-grade cultural paper and paperboard as well as paper and paperboard with high sanitary indexes replacing bleached hardwood pulp or bleached hardwood pulp mixed with bleached softwood kraft pulp.

Application Domain

Pretreatment with alkaline reacting compoundsWater-repelling agents addition +12

Technology Topic

ChemistryHardwood +13

Examples

Experimental program(3)
Effect test(1)

Example Embodiment

[0082] Example 1

[0083] A method for producing high-whiteness chemical pulp and paper products thereof from corn stalks. The corn stalks include depited and unpitched corn stalk husks and corn stalk whole stalks, and the pulping method , including cooking and bleaching methods, wherein: (1), the cooking method adopts the cooking method of the caustic soda method of adding anthraquinone and surfactant; (2), the bleaching method adopts O P AP O Short-program fully chlorine-free bleaching method;

[0084] (1), cooking method, adopts the cooking method of the caustic soda method of adding anthraquinone and surfactant, and its cooking process is:

[0085] 1), cut the air-dried corn stalk husks after depiting into pieces with a length of 3 to 4 cm, remove dust, leaves and scraps, put them into a 15-liter electric heating rotary cooking pot, add cooking liquid, Cover the pot and cook. The cooking adopts the caustic soda method with the addition of anthraquinone and surfactant, and the cooking chemicals and cooking process conditions are as follows:

[0086] Cooking medicine dosage/%

[0087] Sodium hydroxide (mass percent to absolute dry tablet) 17.0

[0088] Anthraquinone (mass percentage to absolute dry tablet) 0.05

[0089] Sodium dodecyl benzene sulfonate surfactant (mass percentage to absolute dry tablet) 0.1

[0090] Liquid ratio (the mass ratio of the total liquid including the moisture of the tablet to the absolutely dry tablet) 7:1

[0091] Cooking temperature: 155℃

[0092] Time to rise to cooking temperature: 70min

[0093] Holding time: 50min.

[0094] 2) After cooking, the pulp after cooking was washed, screened with a laboratory flat screen screen (screen slot 0.2mm), and the yield of coarse pulp was 44.83%, the yield of fine pulp was 43.68%, and the rate of screen residue was measured. 0.19%, residual alkali 2.92g.L -1 and pulp Kappa value of 15.1.

[0095] (2), bleaching method, adopts O P AP O Short-program completely chlorine-free bleaching method

[0096] use O P AP O The short-program full chlorine-free bleaching method bleaches the unbleached corn stalk husk fine pulp obtained by cooking. The bleaching process of each stage is as follows:

[0097] 1), O P part

[0098] O P In the first stage, a small amount of hydrogen peroxide-enhanced oxygen delignification is carried out on the above-mentioned cooked corn stover pulp.

[0099] Place the above-mentioned corn stalk husk pulp in a 15-liter electric heating rotary oxygen bleaching pot, add bleaching chemicals, stir evenly, cover the pot, and introduce oxygen to carry out oxygen delignification. P The section process conditions are:

[0100] Chemicals Dosage/% Oxygen pressure/MPa Bleaching temperature: 115℃

[0101] NaOH 2.5 0.4 Holding time: 90min

[0102] Na 2 SiO 3 1.0 Pulp Consistency: 12%

[0103] MgSO 4 0.1

[0104] H 2 O 2 0.7

[0105] above O P The dosage of chemicals in each section is the mass percentage of chemicals to absolutely dry corn stover pulp.

[0106] The results of pulp oxygen delignification treatment are: Kappa value of pulp after delignification is 4.1, viscosity is 1076ml.g -1 , the pulp yield was 96.25%.

[0107] 2), Section A

[0108] Section A is the opposite of O P The pulp after the section treatment is acid-treated, and the O P The pulp after segmental treatment is put into a 15-liter electric heating rotating stainless steel pot, adding sulfuric acid, stirring evenly, covering the pot, and performing acid treatment. The acid treatment process conditions are:

[0109] temperature/℃ 40

[0110] pH 2.5

[0111] time/min 25

[0112] Pulp concentration/% 10

[0113] After the acid treatment is completed, the pulp is washed.

[0114] 3), P O part

[0115] P O Stage A, oxygen-enhanced hydrogen peroxide bleaching is performed on the cornstalk pulp treated in stage A.

[0116] Put the pulp treated in stage A into a 15-liter electric heating rotary bleacher, add bleaching chemicals, stir evenly, cover the pot, and introduce oxygen to conduct oxygen-enhanced hydrogen peroxide bleaching, P O The section process conditions are:

[0117] Chemicals Dosage/% Oxygen pressure/MPa Bleaching temperature: 115℃

[0118] H 2 O 2 4 0.3 Holding time: 90min

[0119] NaOH 1.5 Pulp concentration: 10%

[0120] Na 2 SiO 3 1.0

[0121] MgSO 4 0.1

[0122] P O After the stage bleaching, the pulp is washed, the brightness of the obtained pulp is 87.51% ISO, and the viscosity is 745m1.g -1.

[0123] Using laboratory standard beating equipment PFI mill, the above-mentioned PFI O The partially bleached corn stalk husk pulp was beaten, with a pulp loading of 22.5 g (calculated as absolute dry pulp), a pulp concentration of 10%, and a pulping beating degree of 50°SR, and a laboratory sheet former was used to make pulp sheets. The physical properties of pulp tension were measured by the national standard testing method, and the test results were: tightness 0.670g.cm -3 , the fracture length is 5.94km, and the tear index is 6.10mN.m 2.g -1 , burst index 4.04kPa.m 2.g -1 , folding endurance 187 times.

Example Embodiment

[0124] Example 2

[0125] Example 2 was repeated according to the method steps and process conditions described in Example 1, except that the raw material used was the whole corn stalk. The unbleached corn stalk whole stalk pulp obtained by cooking has a coarse pulp yield of 43.68%, a fine pulp yield of 42.15%, a screen residue rate of 0.25%, and a residual alkali of 2.13 g.L -1 , the pulp Kappa value is 18.6.

[0126] via O p The Kappa value of corn stalk whole stalk pulp after segment treatment is 4.5, and the viscosity is 1075ml.g -1 , the pulp yield was 91.63%. via P o Stage bleached cornstalk whole stalk pulp had a brightness of 85.10% ISO and a viscosity of 746ml.g -1.

[0127] The physical properties of the pulp sheet made from the above-mentioned corn stalk whole stalk pulp are: tightness 0.671g.cm -3 , the fracture length is 5.67km, and the tear index is 5.80mN.m 2.g -1 , burst index 2.54kPa.m 2.g -1 , folding endurance 156 times.

Example Embodiment

[0128] Example 3

[0129] The high-brightness corn stalk husk pulp and corn stalk whole stalk pulp prepared according to the methods of Example 1 and Example 2, respectively, were used alone or combined with bleached softwood kraft pulp to make hand sheets and machine-made paper.

[0130] The above-mentioned high-brightness corn stalk husk pulp, corn stalk whole stalk pulp and bleached softwood kraft pulp were beaten with a laboratory Valley beater respectively, with a pulp loading of 400g (calculated as absolute dry pulp) and a beating concentration of 2%. The pulping beating degree is 35°SR. According to the different pulp ratios listed in Table 1, handsheets were made on a laboratory sheet former; according to the different pulp ratios listed in Table 2, high-quality writing paper and xerographic paper were made on a laboratory Fourdrinier paper machine. In order to improve the performance of the paper, chemical additives are added to the pulp. The chemical additives used and their dosages are as follows:

[0131] Chemical additive dosage/%

[0132] Filler CaCO 3 25

[0133] Brightener 0.05

[0134] Enhancer Cationic Starch 0.5

[0135] Sizing agent AKD 0.1

[0136] Retention and drainage aid cationic polyacrylamide 0.05

PUM

Property	Measurement	Unit
Length	3.0 ~ 4.0	cm
Tear index	6.1	m²·mN/g
Burst index	4.04	kPa·m²/g

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