KR890001974B1 - Method for preparation of neutral paper - Google Patents

Abstract

A method for prepg. neutral paper (pH 6-7) comprises (i) adding alum (0.2-0.4% amts.) to pulp chest for the rising pH of head box to 6-7 (neutral) to form neutral wet-sheet and dry; and (ii) putting surface sizer (0.1-1.0% amts.) i.e. styrene maleic anhydride (SMA), alkyl ketene dimer (AKD), polyvinyl alcohol (PVA) into a size press.

Description

Manufacturing method of neutral paper

1 is a process schematic diagram of the present invention.

2 is a schematic view of a conventional process.

The present invention relates to a method for producing neutral paper. The present invention in more detail to produce a conventional acidic paper neutral to increase the durability of the paper and increase the sharpness of the printing at the same time to reduce the inorganic salts generated in the paper manufacturing process neutral paper to alleviate the pollution problem of wastewater treatment It relates to a manufacturing method of.

Conventionally, by adding rosin size as a sizing agent and using excess alum, the pH of the paper has an acid of 4 to 5, so that the shelf life of the paper is not long. Has left the problem of wastewater treatment. In addition, since the size of the sizing agent was made at the beginning of the process, the surface of the paper was not smooth and the printing was inconvenient. The ink drying speed was slow, the printing speed was slowed, and the paper strength was not as expected.

More specifically, the excess alum fills the wire holes of the long-term paper machine, resulting in slower dehydration, which reduces production, reduces the effectiveness of amphoteric starch or synthetic polymers, and shortens the life of the machine due to high mechanical corrosion. This has been.

Disadvantages and problems of such a conventional process have been solved by the method for producing a neutral paper of the present invention.

In the manufacture of neutral paper, the pulp chest filled with pulp and filler is used as a sizing agent. Styrene maleic Anhydride, a surface sized agent, is dispersed in a size press after increasing the pH of the conventional 4-5 to 6-7 neutral from the acid of 4-5. SMA) or alkyl ketene dimer (AKD) or polyvinyl alcohol (PVA) or fatty acid chromium complex (such as stearate chromin chloride as complex salt) It is to prepare a neutral paper (PH6-7) that prevents and reduces the water absorption.

Conventionally, 0.5-3% of rosin size is added to pulp chest containing pulp and filler as a sizing agent, and 2-6% of alum is added to the pump inlet by weight to fix the rosin size to the fiber. A positive starch or a synthetic polymer (Polymer), etc., is added to the inlet by 0.1-0.5% to allow the fine fibers to coagulate to some extent. Water is dehydrated to form wet sheets and the wetlands are pressed in the press to remove some of the wetland's moisture and at the same time increase wetland density. Compressed wetlands remove some of the wetland moisture and at the same time increase wetland density. Compressed wetlands are co-dried in the pre-drying step, coated with 5-15% gelatinized starch in the size press, and then re-dried in the drying step to achieve moisture 4-8 and then surfaced in a calender. Press mechanically smoothly and wind the product in the winder to complete. In this case, the above disadvantages and problems have been caused.

The method of the present invention is described in more detail as follows.

The use of rosin size as the size added to the pulp chest is discontinued and the amount of alum added to the feed pump inlet is added from 2 to 6% to 0.2 to 0.4%.

In the second step, the raw material is diluted in white water dehydrated in the silo 2 in the sixth step.

In the third step, the heavy material is removed by centrifugal force in a centrifugal cleaner (3). Next, before entering the fourth step, 0.01 to 0.5% of the synthetic polymer is added. Examples thereof include polyacrylamide and polyethyleneimine.

In the fourth process, the fiber 4 and other non-fibers are removed through the screen 4.

In the fifth step, the raw material is evenly dispersed in the head box 5.

In the sixth step, the wetlands are formed after dehydration on the rotating perforated paper machine 6. The dehydrated water at this time is refluxed through a white water silo to the second process.

In the seventh step, some of the water is removed between the rotating press rolls of the presser 7 and the density of the wetland is increased.

In the eighth process, the wetland is passed through several cylinder dryers of the Pry dryer (8) to obtain 3 to 6% wetland moisture.

In the ninth step, the whole paper of step 13 (injecting and dissolving chemicals) tank 13, the vibrating screen 14 of step 14, and the starch of step 15 are supplied to the dried paper surface using a size press 9. The gelatinized starch obtained from the tank 15 is applied. At this time, 0.1 to 1.0% of the surface size agent is added to the starch supply tank 15. It may be composed of each or a combination thereof, for example, styrenemale anhydride SMA and PVA, AKD, AKD and PVA and the like.

In the tenth step, the wet marsh is again passed through several cylinder dryers of the after dryer (10) to dry the moisture to 4 to 8%.

In the eleventh step, the surface dried in the above step is polished smoothly by the polisher 11.

In the 12th process, it winds up by the winding machine 12 and completes paper.

The above manufacturing process will be described in more detail with reference to the following examples. However, this is for the purpose of illustrating the present invention, but not for limiting it.

Example 1

1) Dissolve the pulp in water at a concentration of 4 to 5% and mix 20 to 30% of talc or calcium carbonate to form a raw material.

2) The raw material prepared by using the dehydrated white water in the next 6 steps is diluted to a concentration of 0.6 to 1.0% and the temperature is maintained at 35 to 45 ° C. Adjust pH to 6-7.

3) After centrifugal cleaner, 0.1 to 0.3% of polyacrylamide is added as a cationic synthetic polymer.

4) Allow the injected chemical to dilute as it passes through the screen, and also remove fiber bundles and other fine materials.

5) Evenly distribute the raw materials in the head box.

6) We make wetland with concentration of 15 to 20% after dehydration in Jangmanchoji.

7) After pressing in the rolling roll, the dry volume is 40-50% of the wetland.

8) Use steam to dry 3 ~ 6% of water in all dryers at 100 ~ 140 ℃.

9) In a size press, 0.5 to 1% of styrene maleic anhydride is applied to the surface of paper as a surface size to starch prepared at a concentration of 5 to 10% and a temperature of 30 to 50 ° C. In other cases, it is also added as ingredients.

10) Again, wet wetlands are passed through several post-dryers at temperatures between 100 and 140 ° C to have 4-8% moisture.

11) Press the pressure 50 ~ 100kg / cm on the polisher to polish it.

12) Cut and finish the neutral paper of PH6-7 in the winder according to the standard.

Example 2

Conventional method

1) Dissociate the pulp in water at a concentration of 4 to 5% and mix the talc with 20 to 30% of the pulp to form a raw material. Then add 0.5 to 3% rosin size and 2 to 6% ALUM again.

2) When in the same manner as in Example 1, PH is 4 to 5.

3) After passing through the cleaner, add 0.1 to 0.5% of the positive part.

4) -8) The process is the same as in Example 1.

9) In the size press, apply starch prepared at a concentration of 5 to 10% and a temperature of 30 to 50 ° C on the paper surface.

10) -11) The process is the same as in Example 1.

12) Complete the acidic paper of PH4-5 in the winder.

Example 3

Comparative Example

The neutral paper of the present invention obtained in Examples 1 and 2 is compared with conventional acid paper. That is, the quality and deterioration resistance comparison is as follows.

It can be seen that the neutral paper obtained by the method of the present invention maintains significantly superior quality as compared to the conventional acidic paper.

The paper by the method of the present invention neutralizes the pH of 6 to 7, the longer the shelf life of the paper, the surface of the paper is smoother, the print is clearer, the ink drying speed is increased, thereby increasing the printing speed, It is possible to use low-grade raw materials with low strength because of its high strength, and it is easy to treat wastewater due to the reduction of inorganic salt use.

Claims (3)

In preparing neutral paper, add 0.2 to 0.4% of alum to the pulp chest to raise the pH of the head box to 6 to 7 neutral, form neutral wet paper and dry it, and then use a size sized 0.1 to 1.0% on the size press. Method for producing a neutral paper of PH6 to 7 characterized in that the input. The method of claim 1, wherein the surface sizing agent is composed of styrene maleic anhydride, or an alkyl ketene dimer or polyvinyl alcohol or fatty acid cron complex. The surface sizing agent according to claim 2 is introduced into styrene male anhydride, styrene male anhydride and polyvinyl alcohol, alkyl ketene dimer, or an individual or a combination thereof consisting of alkyl ketene dimer and polyvinyl alcohol. PH6 to 7 method of producing a neutral paper.

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