Method for fabrication food wrap paper and cultural paper by using corn stalk to make no chlorin bleached pulp

Abstract

A process for preparing food packing paper and cultural paper with chlorine free bleached paper pulp includes using corn straw or its pitch free ones as raw material, then cutting, dust removing, presoaking, cooking and bleaching. The cooking reagent uses ammonium sulfite and potassium sulfite or sodium sulfite as main, sulfur or sulfourea as assistant and urea as well as sodium hydroxide as buffer. The bleaching is two sections or multisection bleaching by using urea or sulfourea to protect fibre and activate hydrogen peroxide.

Description

Technical field

[0001] The present invention belongs to pulping and papermaking technology, and in particular relates to a technology for producing completely chlorine-free bleached pulp from corn stalks and de-pithed corn stalks to produce food packaging paper and paperboard, cultural paper and paperboard that are in direct or indirect contact with food and human body . Background technique

[0002] The paper industry usually uses long-fiber coniferous wood, medium-fiber-length hardwood, bamboo, reed and short-fiber rice straw as the basic raw materials for papermaking. The manufacturing process usually uses traditional chemical pulping methods, mainly alkaline methods (including the addition of anthracene Alkali method such as quinone) cooking and acid cooking process, using alkali or acid as the main cooking agent; neutral sodium sulfite method (Na 2 SO 3 As cooking agent) and alkaline sodium sulfite method (Na 2 SO 3 Add NaOH as cooking agent). Bleaching treatment generally a...

Examples

example 1

[0032] The cooking uses corn stalks as the raw material, after being cut, dusted, and pre-soaked, then put into the cooker. The weight percentage of the medicine to the absolutely dry corn stalks is:

[0033] Ammonium sulfite 15~20%

[0034] Potassium sulfite 3~7%

[0035] Urea 1.5~3.5%

[0036] Sulfur 0.5~2%

[0037] The process conditions of steaming ball cooking are: liquid ratio 2.8, heating time 1 hour, heating to 160°C, and heat preservation for 2 hours.

[0038] Pulp bleaching adopts a hydrogen peroxide bleaching process with simultaneous reinforcement of oxygen and alkali and urea activation. The bleaching process is:

[0039] The weight percentage of the medicine to the absolute dry unbleached pulp is:

[0040] Hydrogen peroxide 0.5~2%

[0041] Urea 0.4~1.5%

[0042] Magnesium sulfate 0.3%

[0043] Sodium silicate 1~3%

[0044] Sodium hydroxide 2~6%

[0045] Pulp concentration 8%

[0046] Oxygen flow under 0.5MPa oxygen pressure

[0047] Treated at 80°C for 1 hour to obta...

example 2

[0049] Steaming uses depithed corn stalks as raw materials, cuts, dusts, and presoaks, and then puts them into the digester. The weight percentage of the medicine to the absolutely dry depithed cornstalk is:

[0050] Ammonium sulfite 15~24%

[0051] Potassium sulfite 3~10%

[0052] Urea 1~4%

[0053] Sulfur 0.35~3%

[0054] The process conditions of steaming ball cooking are: liquid ratio 2.8, heating time 1 hour, heating to 165°C, holding for 2 hours,

[0055] Pulp bleaching adopts the hydrogen peroxide bleaching process in which oxygen and alkali are simultaneously strengthened and urea is activated. The process conditions are:

[0056] The weight percentage of the medicine to the absolute dry unbleached pulp is:

[0057] Hydrogen peroxide 0.8~3%

[0058] Urea 0.5~2%

[0059] Magnesium sulfate 0.3~1%

[0060] Sodium silicate 1~4%

[0061] Sodium hydroxide 2.5~7%

[0062] Pulp concentration 8%

[0063] Oxygen flow under the oxygen pressure of 0.5MPa

[0064] Treated at 90°C for 1....

example 3

[0066] Using de-pithed corn stalk as raw material, after cutting, dusting and pre-soaking, put it into the digester, the weight percentage of the medicine to the absolutely dry de-pithed corn stalk is:

[0067] Sodium sulfite 12~20%

[0068] Potassium sulfite 2~5%

[0069] Sodium hydroxide 1.5~5%

[0070] Sulfur 0.3~1%

[0071] The process conditions of steaming ball cooking are: liquid ratio 3, heating time 1 hour, heating to 155°C, and heat preservation for 2 hours.

[0072] Pulp bleaching adopts a hydrogen peroxide bleaching process in which oxygen and alkali are simultaneously strengthened and urea is activated. The process conditions are:

[0073] The weight percentage of the medicine to the absolute dry unbleached pulp is

[0074] Hydrogen peroxide 0.8~2%

[0075] Urea 0.5~1%

[0076] Magnesium sulfate 0.3~1%

[0077] Sodium silicate 1~3%

[0078] Sodium hydroxide 1.5~5%

[0079] Pulp concentration 8%

[0080] Oxygen flow under the oxygen pressure of 0.5MPa

[0081] Treated ...

Technical field

[0001] The present invention belongs to pulping and papermaking technology, and in particular relates to a technology for producing completely chlorine-free bleached pulp from corn stalks and de-pithed corn stalks to produce food packaging paper and paperboard, cultural paper and paperboard that are in direct or indirect contact with food and human body . Background technique

[0002] The paper industry usually uses long-fiber coniferous wood, medium-fiber-length hardwood, bamboo, reed and short-fiber rice straw as the basic raw materials for papermaking. The manufacturing process usually uses traditional chemical pulping methods, mainly alkaline methods (including the addition of anthracene Alkali method such as quinone) cooking and acid cooking process, using alkali or acid as the main cooking agent; neutral sodium sulfite method (Na 2 SO 3 As cooking agent) and alkaline sodium sulfite method (Na 2 SO 3 Add NaOH as cooking agent). Bleaching treatment generally a...

Examples

example 1

[0032] The cooking uses corn stalks as the raw material, after being cut, dusted, and pre-soaked, then put into the cooker. The weight percentage of the medicine to the absolutely dry corn stalks is:

[0033] Ammonium sulfite 15~20%

[0034] Potassium sulfite 3~7%

[0035] Urea 1.5~3.5%

[0036] Sulfur 0.5~2%

[0037] The process conditions of steaming ball cooking are: liquid ratio 2.8, heating time 1 hour, heating to 160°C, and heat preservation for 2 hours.

[0038] Pulp bleaching adopts a hydrogen peroxide bleaching process with simultaneous reinforcement of oxygen and alkali and urea activation. The bleaching process is:

[0039] The weight percentage of the medicine to the absolute dry unbleached pulp is:

[0040] Hydrogen peroxide 0.5~2%

[0041] Urea 0.4~1.5%

[0042] Magnesium sulfate 0.3%

[0043] Sodium silicate 1~3%

[0044] Sodium hydroxide 2~6%

[0045] Pulp concentration 8%

[0046] Oxygen flow under 0.5MPa oxygen pressure

[0047] Treated at 80°C for 1 hour to obta...

example 2

[0049] Steaming uses depithed corn stalks as raw materials, cuts, dusts, and presoaks, and then puts them into the digester. The weight percentage of the medicine to the absolutely dry depithed cornstalk is:

[0050] Ammonium sulfite 15~24%

[0051] Potassium sulfite 3~10%

[0052] Urea 1~4%

[0053] Sulfur 0.35~3%

[0054] The process conditions of steaming ball cooking are: liquid ratio 2.8, heating time 1 hour, heating to 165°C, holding for 2 hours,

[0055] Pulp bleaching adopts the hydrogen peroxide bleaching process in which oxygen and alkali are simultaneously strengthened and urea is activated. The process conditions are:

[0056] The weight percentage of the medicine to the absolute dry unbleached pulp is:

[0057] Hydrogen peroxide 0.8~3%

[0058] Urea 0.5~2%

[0059] Magnesium sulfate 0.3~1%

[0060] Sodium silicate 1~4%

[0061] Sodium hydroxide 2.5~7%

[0062] Pulp concentration 8%

[0063] Oxygen flow under the oxygen pressure of 0.5MPa

[0064] Treated at 90°C for 1....

example 3

[0066] Using de-pithed corn stalk as raw material, after cutting, dusting and pre-soaking, put it into the digester, the weight percentage of the medicine to the absolutely dry de-pithed corn stalk is:

[0067] Sodium sulfite 12~20%

[0068] Potassium sulfite 2~5%

[0069] Sodium hydroxide 1.5~5%

[0070] Sulfur 0.3~1%

[0071] The process conditions of steaming ball cooking are: liquid ratio 3, heating time 1 hour, heating to 155°C, and heat preservation for 2 hours.

[0072] Pulp bleaching adopts a hydrogen peroxide bleaching process in which oxygen and alkali are simultaneously strengthened and urea is activated. The process conditions are:

[0073] The weight percentage of the medicine to the absolute dry unbleached pulp is

[0074] Hydrogen peroxide 0.8~2%

[0075] Urea 0.5~1%

[0076] Magnesium sulfate 0.3~1%

[0077] Sodium silicate 1~3%

[0078] Sodium hydroxide 1.5~5%

[0079] Pulp concentration 8%

[0080] Oxygen flow under the oxygen pressure of 0.5MPa

[0081] Treated ...