KR101751273B1

KR101751273B1 - Method for Manufacturing Paper Using Pulp with High Fines Content And Dry Strength Agent

Info

Publication number: KR101751273B1
Application number: KR1020150122800A
Authority: KR
Inventors: 유정용; 정성현
Original assignee: 강원대학교산학협력단; 주식회사 전주페이퍼
Priority date: 2015-08-31
Filing date: 2015-08-31
Publication date: 2017-07-11
Also published as: KR20170025813A

Abstract

The present invention relates to a method for producing pulp paper containing a large amount of fine fibers using a dry strength increasing agent. The method of the present invention has an advantage of improving the effect of the dry strength enhancer even under the production conditions in which the content of fine fibers is high or the fine fibers can not be retained because the dry strength enhancing pulp containing the dry strength enhancer is used, It is possible to produce a low basis weight paper by a high speed papermaking method even if the classification of the fine fibers is not performed since the dry strength enhancer is not lost by the fine fibers. Further, since the production method of the present invention can produce a low basis weight paper having a high tensile strength by using recycled pulp containing a large amount of fine fibers, there is an effect of increasing utilization of circulating paper resources.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a pulp paper containing a large amount of fine fibers using a dry strength increasing agent,

The present invention relates to a method for producing pulp paper containing a large amount of fine fibers using a dry strength increasing agent.

Paper is generally made up of pulp (paper stock). The pulp is produced from wood by mechanical or chemical methods and is present in the form of fine pulp fibers (fines) and long pulp fibers (long fibers) depending on the particle size. Pulp, which is a cellulose-based material, forms a hydrogen bond by the hydroxyl groups on the fiber surface during the drying of surface sized paper. The pulp is adhered to each other by the hydrogen bonding to determine the strength of the paper. The strength of the paper therefore depends on how smoothly the hydrogen bonds between the fibers are formed. Methods for promoting hydrogen bonding between fibers include beating treatment. Refining processes improve the flexibility of the pulp and form surface fibrils. However, the high-temperature treatment promotes the microfibrillation and maintenance of the long fibers, which slows the dehydration and drying in the paper making process and lowers the tear strength of the paper. Especially, the formation of microfibers is increased by the treatment of keratinized regeneration. In order to compensate for the above disadvantages of the disinfection process, a method has been developed in which a dry strength agent is added to pulp so that additional hydrogen bonds are formed in addition to hydrogen bonds due to a hydroxyl group between pulps. However, the microfibers have a higher adsorption power to the dry strength enhancer than the long fiber, and the dry strength enhancer adsorbed to the microfibers is lost during the papermaking process. Therefore, in order to improve the effect of the dry strength agent, it is necessary to completely separate (separate) the fine fibers from the pulp, classify and classify the pulp, and then add the dry strength agent to only the long fibers, The dry strength enhancer should improve the retention of the adsorbed microfibers. However, it is very difficult to completely classify fine fibers or to improve the retention of fine fibers adsorbed by the dry strength enhancer, and it is particularly difficult to prepare low grammage paper produced by the high-speed papermaking method. Recycled pulp made from recycled paper, which is a poorly strength recycled pulp paper resource, basically contains 30% or more of fine fibers. Therefore, in order to recycle paper as a circulating paper resource, it is urgently required to develop a technique for improving the strength of paper produced without classifying fine fibers for a pulp containing a large amount of fine fibers.

The patent documents and references cited herein are hereby incorporated by reference to the same extent as if each reference was individually and clearly identified by reference.

Korean Patent No. 10-1395270

As a result of efforts to produce a paper using pulp containing a large amount of microfine fibers, the present inventors have found that pulp containing a large amount of microfine fibers and pulp containing a large amount of microfine fibers The present inventors have completed the present invention by experimentally confirming that it is possible to produce a low basis weight paper having improved tensile strength of paper by a high speed papermaking method because there is no loss of the dry papermaking enhancer due to fine fibers.

Accordingly, an object of the present invention is to provide a method for producing a pulp paper containing a large amount of fine fibers using a dry strength increasing agent.

Other objects and technical features of the present invention will be described in more detail with reference to the following detailed description, claims and drawings.

According to one aspect of the present invention, the present invention provides a method of making a pulp comprising: (a) preparing a pulp for enhancing dry strength; (b) mixing the dry strength increasing pulp with a pulp containing a large amount of fine fibers; And (c) papermaking the mixed pulp to prepare paper. The present invention also provides a method for producing pulp paper containing a large amount of fine fibers using a dry strength enhancer.

The term " dry strength enhancer " of the present invention means a polyelectrolyte having a polar functional group capable of hydrogen bonding, which is mixed with pulp to improve the strength of paper. The dry strength enhancer is mainly a polyacrylamide-based polymer electrolyte, but is not limited thereto. The polyacrylamide-based polymer electrolyte may be a cationic polyacrylamide, anionic polycarylamide, or amphoteric polyacrylamide, depending on the monomer to be copolymerized with acrylamide. amphoteric polyacrylamide), or polyvinylamine prepared through chemical modification, but the present invention is not limited thereto.

According to one embodiment of the present invention, the dry strength agent for use in the present invention is polyvinylamine. The polyvinylamine has an amine group polymerized on an acrylamide polymer backbone. The amine group polymerized on the polyvinylamine is smaller in size than an acyl group or a carboxy group polymerized on the polyacrylamide-based polymer electrolyte. Therefore, the polyvinylamine may have a more flexible conformation in an aqueous solution than the polyacrylamide-based polymer electrolyte. The base determines the flexibility of the dry strength agent and the flexibility is proportional to the adsorption rate and adsorption strength of the dry strength agent to the pulp. Therefore, the polyvinylamine of the present invention has a significantly higher adsorption rate and adsorption strength than the polyacrylamide-based polymer electrolyte.

The term " pulp containing a large amount of fine fibers " of the present invention means pulp having a content of fine fines of 5% or more. The fine fibers mean pulp fibers having a particle size of 200 mesh or less. According to one embodiment of the present invention, the pulp containing a large amount of the fine fibers means pulp having a content of the fine fibers of 5-50% by weight. Preferably, the pulp containing a large amount of the fine fibers means pulp having a content of the fine fibers of 15 to 40% by weight. More preferably, the pulp containing a large amount of the fine fibers means pulp having a content of the fine fibers of 30% by weight. The pulp containing a large amount of the fine fibers increases the papermaking time and lowers the paper strength. The pulp containing a large amount of the fine fibers may be a mechanical pulp or a recycled pulp. The mechanical pulp may contain a large amount of microfine fibers (primary microfine fibers) formed during the process of mechanically crushing, crushing, or fusing wood to produce pulp, and the microfine fibers 2 And microfine fibers) may be formed and included. The recycled pulp may contain a large amount of microfine fibers (secondary microfine fibers) formed during the process of keratinization in the course of regeneration of the paper or recycling the recycled paper resources to the weak pulp with weak strength. The microfibers have a specific surface area 200 times wider than the long fibers. The adsorption rate of the dry strength agent is proportional to the specific surface area of the substrate. The substrate of the dry strength enhancer may be fine fibers or long fibers. Therefore, when a certain amount of fine fibers are present in the pulp, most of the dry strength enhancer is adsorbed on the fine fibers. Since the fine fibers have a particle size of 200 mesh or less, they can not be left on the web in the papermaking process and are all lost. The fine fibers are hardly changed in particle size even when the dry strength enhancer is adsorbed. Therefore, when the dry strength enhancer is adsorbed on the fine fibers, all of them are lost in the papermaking process like microfibers, so that the effect of the dry strength enhancer is significantly deteriorated. The mechanical pulp or the recycled pulp contains a large amount of microfibers. Particularly, the recycled pulp generally contains 30% or more of fine fibers. Therefore, in order to improve the effect of the dry paper strength enhancer in the production of paper using the mechanical pulp or the recycled pulp, a method of preventing loss of the dry paper strength enhancer in the papermaking process is required. In the present invention, pulp for enhancing dry strength is prepared and used as a method for preventing the loss of the dry strength agent during the papermaking process. The term " pulp for increasing dry strength " in the present invention means pulp in a state in which a high content of dry strength increasing agent is adsorbed on the long fiber.

According to an embodiment of the present invention, the dry strength increasing agent is adsorbed on the long fibers by 90% -99.9%. Preferably, the dry strength increasing reinforcing agent is 95% -99.9% adsorbed on the long fiber. More preferably, the dry strength enhancement agent is 98% -99.9% adsorbed on the long fiber. The pulp for increasing dry strength is added to pulp having a high content of fine fibers to improve the retention of the dry strength enhancer. Therefore, the use of the pulp for enhancing the strength of the dry strength enhances the effect of the dry strength enhancer even under production conditions in which mechanical pulp or recycled pulp containing a large amount of fine fibers is used or in which microfibers can not be retained.

According to an embodiment of the present invention, the dry strength enhancing pulp includes the dry strength enhancer and pulp containing a large amount of long fibers, and may be used regardless of whether it is dry or not.

According to another embodiment of the present invention, the dry strength agent used in the pulp for increasing dry strength is polyvinylamine. The polyvinylamine exhibits a significantly higher adsorption ratio and adsorption strength than the polyacrylamide-based polymer electrolyte, and thus is suitable for producing the pulp for enhancing the dry strength. The term " pulp containing a large amount of long fibers " in the present invention means pulp having a long fiber content of 95 to 99.9% by weight. The long fibers mean pulp fibers having a particle size exceeding 200 mesh.

According to an embodiment of the present invention, the pulp containing a large amount of the long fibers means pulp having a content of the long fibers of 95-99.9 wt%. Preferably, the pulp containing a large amount of the long fibers means pulp having a content of the long fibers of 97 to 99.9% by weight. The pulp containing a large amount of the long fibers may be a chemical pulp. The chemical pulp may be manufactured by a bleaching method, a sulfurous acid method, a soda method or a sulfate method (Kraft method), but is not limited thereto. The chemical pulp has a merit in that microfibers due to mechanical fibrillation are not formed because the lignin component of the wood is removed through chemical treatment to produce pulp.

According to a specific embodiment of the present invention, the pulp containing a large amount of the long fibers of the present invention may be softwood kraft pulp, but any pulp having a long fiber content of 95 wt% or more can be used without limitation.

According to another embodiment of the present invention, the dry strength increasing pulp is added to the pulp containing the long fiber at a ratio of 5-15% by weight. Preferably, the dry strength increasing pulp is added in an amount of 7-12% by weight based on the pulp containing a large amount of the long fiber. More preferably, the dry strength increasing reinforcing agent is added to the pulp containing a large amount of the long fiber at 9% by weight.

According to another embodiment of the present invention, the dry strength increasing pulp may be prepared by adding the dry strength increasing agent to a pulp containing a large amount of the long fibers, and then adding an anionic polyacrylamide to the pulp containing a large amount of the long fibers By weight based on the total weight of the composition. Preferably, the dry strength increasing pulp is added to the pulp containing a large amount of the long fiber, and then an anionic polyacrylamide is added to the pulp containing a large amount of the long fiber in an amount of 5-7 wt% Lt; / RTI > More preferably, the dry strength increasing pulp is added to the pulp containing a large amount of the long fiber, and then an anionic polyacrylamide is added to the pulp containing a large amount of the long fiber in an amount of 6 wt% . The anionic polyacrylamide has the effect of neutralizing the charge of the polyvinylamine to increase the formation of hydrogen bonds between the fibers. The dry strength increasing pulp is mixed with the dry strength increasing agent and the pulp containing a large amount of the long fibers, and then the polyacrylamide is added and stirred sufficiently. The agitation is sufficiently carried out until the dry strength enhancer and the polyacrylamide can be completely adsorbed to pulp containing a large amount of the long fibers.

According to an embodiment of the present invention, in step (b), the dry strength increasing pulp is added in an amount of 5-40% by weight to the pulp containing a large amount of the fine fibers. Preferably, the dry strength increasing pulp is added in an amount of 20 to 35% by weight based on the pulp containing a large amount of the fine fibers. More preferably, the dry strength increasing pulp is added in an amount of 30% by weight based on the pulp containing a large amount of the fine fibers.

According to another embodiment of the present invention, the mixed pulp is papermaking to produce paper.

The features and advantages of the present invention are summarized as follows:

(I) The present invention relates to a method for producing pulp paper containing a large amount of fine fibers using a dry strength increasing agent.

(Ii) Since the method of the present invention uses pulp for enhancing dry strength containing a dry strength increasing agent, it has an advantage of improving the effect of the dry strength increasing agent even under production conditions in which the content of fine fibers is high or the minute fibers can not be retained have.

(Iii) Since the dry strength enhancer is not lost by the microfibers during the papermaking process, the low papermaking paper can be produced by the high-speed papermaking method without performing classification of the microfibers.

(Iv) The production method of the present invention can produce a low basis weight paper having a high tensile strength by using a recycled pulp containing a large amount of microfine fibers, thereby increasing the utilization of circulating paper resources.

Example

In the present invention, instead of the conventional application method of the dry strength increasing agent for putting the dry strength agent directly into the pulp, the pulp for drying strength is selectively prepared by treating the softwood kraft pulp, which is easy to hold, Mechanical pulp having a fiber content of 30% by weight. The mixed pulp was subjected to a papermaking process to prepare paper, and a tensile strength of the paper was measured by preparing it as a sample for strength measurement.

Hereinafter, the method for producing paper using pulp for enhancing dry strength of the present invention and pulp containing a large amount of fine fibers will be described in detail with reference to Examples.

Example 1: Paper manufacture using pulp for enhancing dry strength

This propelled speed 1000m / min Crescent papermaking machine (paper machine) domestic sanitary paper manufacturer micro-fiber content of 30 wt% thermomechanical pulp and fine fiber content in order to produce paper having a basis weight bakyeop of 28g / m ² in which use of Softwood kraft pulp of less than 3% by weight was used. First, pulp for increasing dry strength was prepared. Polyvinylamine (HF-70D, 15% active, SNF Co.) was added to the softwood kraft pulp in an amount of 9% by weight to prepare the pulp for enhancing the strength of the dry strength, and further anionic polyacrylamide (RSL -9400, 15% active, SNF) was added to the softwood kraft pulp at 6 wt%. The mixture of softwood kraft pulp, polyvinylamine and polyacrylamide was thoroughly stirred to allow polyvinylamine and polyacrylamide to be completely adsorbed to the softwood kraft pulp. The pulp for drying strength was pulverized by adding 30% by weight of thermomechanical pulp having a fine fiber content of 30% by weight, followed by papermaking to prepare a paper, and then a specimen for measuring the tensile strength of the paper Prepared.

Comparative Example 1: Paper production using dry strength agent

Grassland speed 1000m / min of Crescent country to use paper machines sanitary paper manufacturer to produce paper having a basis weight bakyeop of 28g / m ² in the fine fiber content of 30 wt% thermomechanical pulp and less than 3% by weight of fine-fiber content for Softwood kraft pulp was used. In Comparative Example 1, the dry strength increasing agent was directly added to the whole pulp according to the conventional method of using the dry strength increasing agent without producing the dry strength increasing pulp. To this end, the softwood kraft pulp was added in an amount of 30% by weight to thermomechanical pulp having a fine fiber content of 30% by weight and mixed. Polyvinylamine (HF-70D, 15% active, SNF) 3% by weight based on the total pulp was added, followed by addition of 2% by weight of anionic polyacrylamide (RSL-9400, 15% active, SNF) to the whole pulp. Considering the ratio of the pulp used in Comparative Example 1, the amounts of the polyvinylamine and polyacrylamide added were the same as those of the polyvinylamine and polyacrylamide used in Example 1. The mixture of the softwood kraft pulp, the thermomechanical pulp, the polyvinylamine and the polyacrylamide was thoroughly stirred to cause the polyvinylamine and the polyacrylamide to be completely adsorbed on the whole pulp, and then the paper was papermaking and a specimen for measuring the tensile strength of the paper was prepared .

Comparative Example 2: Production of paper without using dry strength enhancer

Grassland speed 1000m / min of Crescent country to use paper machines sanitary paper manufacturer to produce paper having a basis weight bakyeop of 28g / m ² in the fine fiber content of 30 wt% thermomechanical pulp and less than 3% by weight of fine-fiber content for Softwood kraft pulp was used. To the whole mixed pulp, the softwood kraft pulp was added in an amount of 30% by weight to thermomechanical pulp having a fine fiber content of 30% by weight and mixed without adding a dry strength increasing agent at all. The pulp mixture was papermaking to produce paper and a paper specimen for paper tensile strength measurement.

Experimental Example 1

The tensile strengths of the specimens prepared from Examples, Comparative Examples 1 and 2 were measured. The measurement results are shown in Table 1.

Tensile Index (Nm / g) Example 1 587.6 Comparative Example 1 509.7 Comparative Example 2 505.5

As shown in the above results, the paper (Example 1) produced by using pulp containing a large amount of pulp for enhancing dry strength and microfine fibers (Comparative Example 1), which was prepared by directly treating the pulp mixture with a dry strength increasing agent The tensile strength increased by 15.3%. The paper tensile strength of the paper prepared by directly treating the dry strength enhancer (Comparative Example 1) was not different from that of the paper prepared without any treatment of the dry strength enhancer (Comparative Example 2). This is because most of the dry strength agent used in Comparative Example 1 was adsorbed on the fine fibers and lost in the papermaking step.

The specific embodiments described herein are representative of preferred embodiments or examples of the present invention, and thus the scope of the present invention is not limited thereto. It will be apparent to those skilled in the art that modifications and other uses of the invention do not depart from the scope of the invention described in the claims.

Claims

(a) 9% by weight of polyvinylamine and 6% by weight of polyacrylamide are added to the softwood kraft pulp having a content of fine fibers of less than 3% by weight and mixed with the softwood kraft pulp, Amine and said polyacrylamide to 98-99.9% adsorbed on said softwood kraft pulp;
(b) mixing thermomechanical pulp having a fine fiber content of 30% by weight with the dry strength increasing pulp at a ratio of 30% by weight to the dry strength increasing pulp; And
(c) papermaking the mixed pulp at a speed of 1000 m / min in a crisson papermaking machine to prepare a tissue paper having a basis weight of 28 g / m ² and a tensile index (Nm / g) of 587.6 Wherein the pulverized paper is pulverized by using a dry strength increasing agent.

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