JP2006104593A - Method for producing bulky paper - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for easily producing bulky paper, by suppressing absorbency of coating solutions which is increased when the bulky paper having a high percentage of voids of paper is produced. <P>SOLUTION: This method for producing the bulky paper has one or more processes for applying the coating solutions to a surface of paper, after a drier part, and a process for making the paper contain a bulking agent having a melting point of such a temperature as to be higher than a temperature of the coating solution having the highest temperature among the coating solutions, before the processes for applying the coating solutions. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention belongs to a method for producing a bulky paper in which the liquid absorption of the coating liquid is suppressed in the step of applying the coating liquid to the paper surface in the paper making process.

In recent years, high quality paper with excellent whiteness, opacity, printability, volume, etc. has been demanded. On the other hand, lightweight paper with low pulp consumption is desired for environmental considerations. . In order to solve these problems by the bulkiness of paper, various methods for improving the bulk have been attempted so far, and one of them is the use of a bulking agent for paper. As the bulking agent for paper, those using a polyhydric alcohol fatty acid ester (Patent Document 1), those using a polymer (Patent Document 2) and the like are known, and some bulking agents are already commercially available and used. ing.
Patent No. 2971447 JP 2002-115199 A

  Recently, however, several problems have been pointed out in the production of bulky paper with bulking agents. One of the problems is that the liquid absorption amount of the coating liquid increases in the size press process and the coating process, which are processes for applying the coating liquid to the paper surface. This is thought to be due to an increase in the porosity of the paper when a bulking agent is used. This increase in liquid absorption may cause a paper breakage problem due to a decrease in strength after the coating liquid is applied to the paper surface. As the drying load increases, secondary problems such as insufficient speed can be caused. The phenomenon of increased liquid absorption is particularly noticeable in a two-roll size press where it is difficult to control liquid absorption due to its structure.

  Although this problem has been dealt with by adding an internal sizing agent or changing the properties of the coating liquid, in general, the addition of the sizing agent has a problem of causing the paper making system to become dirty or cause paper slippage. For this reason, there is a limit, and it is not realistic to change the properties of the coating liquid because it greatly affects the properties of the finished paper surface. In other words, no specific solution useful in the industry has yet been found.

  An object of the present invention is to provide a method for producing a bulky paper more easily than in the past by suppressing liquid absorption of a coating liquid which increases when producing a bulky paper having a high paper porosity.

  The present invention includes at least one step of applying a coating liquid to the paper surface after the dryer part, and the bulking agent having a melting point higher than the temperature of the highest coating liquid among the coating liquids. A method for producing a bulky paper, comprising a step of adding paper to a paper before a liquid coating step.

  Specifically, the following section will explain in detail, but as a bulking agent used internally added in paper, the process of applying a coating liquid on the surface of the paper, particularly the size press process (especially 2) Operation using a material that is higher than the temperature of the coating liquid used in the roll size press) or lowering the temperature of the coating liquid used in the process of applying the coating liquid to the paper surface below the melting point of the bulking agent. The purpose can be achieved. Although the manifestation mechanism of the effect of the present invention is unclear, if a bulking agent having a melting point higher than the temperature of the coating liquid is used, the bulking agent in the paper does not melt even during the process of applying the coating liquid to the paper surface. This is presumably because the physical properties of the additive sizing agent and coating liquid are not adversely affected.

  According to the method for producing bulky paper of the present invention, the liquid absorption of the coating liquid is suppressed in the step of applying the coating liquid to the paper surface in the paper making process, the coating liquid is excessively applied to the surface, the paper is cut, and the subsequent drying process. Drying load can be reduced.

  In general, paper is manufactured in the order of blending, wire part, press part, dryer part, size press and coating. The process of applying the coating liquid to the paper surface of the present invention refers to a process of applying the coating liquid to the paper at a stage after the dryer part, and is a process of coating or impregnating the dried paper with the coating liquid. The coating method is not particularly limited. For example, a 2 roll size press, a bar coater, a roll coater, a reverse roll coater, a blade coater, an air knife coater, a rod coater, a bill blade coater, a gate roll coater, a curtain coater, a die slot coater, and a gravure. Examples include coaters and champlex coaters. In any case of the above-mentioned coating method, the effect of the present invention can be obtained, but in particular, when using a two-roll type coating means in which it is difficult to control the amount of liquid absorption, the two-roll size press has a remarkable effect. can get.

  The two-roll size press has a horizontal, incline and vertical structure, and among them, the horizontal and incline are more effective.

  The coating solution in the size press used in the present invention is, for example, starch such as corn starch, potato starch, tapioca starch, wheat starch, rice starch or oxidized starch, cationized starch, amphoteric starch, urea starch processed from the starch. An aqueous solution of esterified starch or the like is used, and these starch aqueous solutions can be used as an aqueous solution by combining one type of starch or two or more types of starch.

  Similarly, an aqueous solution of polyvinyl alcohol, modified polyvinyl alcohol or the like can be used, and an aqueous starch solution and an aqueous polyvinyl alcohol solution may be used alone, respectively, but they can also be used by mixing at an arbitrary ratio.

  It is also possible to add synthetic sizing agents such as styrene / acrylic, water resistance agents, antifoaming agents, viscosity modifiers, thickeners, etc. An appropriate amount may be blended.

  The coating liquid used in the coating used in the present invention is, for example, one or two pigments such as clay, kaolin, heavy calcium carbonate, light calcium carbonate, titanium oxide, satin white, barium sulfate, and plastic pigment. Slurries mixed and dispersed in water are used, but other adhesives such as styrene / butadiene, acrylic, vinyl acetate, polyvinyl alcohol, starch, proteins, dispersants, thickeners, water retention agents Antifoaming agents, water resistance agents, dyes, and the like are added as necessary. However, the coating liquid that exhibits the effect of the present invention is not particularly limited by the specific description as described above, and the method for preparing the coating liquid is not particularly limited.

  The paper in the present invention is not particularly limited and can be applied to various papers. The types of paper include, for example, non-coated paper and fine-coated paper used for book paper and magazines, printing paper such as coated paper used for catalogs, posters, etc. and their base paper, or ink jet paper, Examples include information paper such as PPC paper, foam paper, thermal paper, pressure-sensitive paper and its base paper, or newsprint paper, packaging paper, and other paperboard such as white paperboard and colored paperboard, and paper made with acid, neutral or alkaline paper. I can do it. Especially, it is used suitably for printing paper and its base paper.

  As a pulp raw material for forming paper, other than kraft pulp, mechanical pulp, groundwood pulp, recycled pulp, chemically modified pulp, synthetic fiber or the like may be used alone or in combination.

  Moreover, as a chemical | medical agent added to a pulp, a filler, a paper strength enhancer, a yield improver, a sizing agent, etc. are used as needed. It is preferable to use a sizing agent from the viewpoint of suppressing liquid absorbency to paper. For this reason, in this invention, it is preferable to have the process of containing a sizing agent in the paper before the process of apply | coating a coating liquid. Here, “before the step of applying the coating liquid to the surface of the paper” means before the step of applying the first coating liquid. As the sizing agent, a general internal sizing agent can be used. Examples of the internally added sizing agent include rosin, alkyl ketene dimer, alkenyl succinic anhydride and the like. From the viewpoint of reducing dirt in the papermaking system and preventing slipping of the paper, the addition amount is preferably 0.01 to 0.5% by weight per pulp.

  The paper in the present invention may be a paper obtained by a general paper machine, and examples of the paper machine include a long net type, a circular net type, a short net type, a twin wire type, and an inclined wire type paper machine. .

  Examples of the wire part include a gap former and a hybrid former.

  The production method of the present invention includes a step of adding a bulking agent to paper before the step of applying a coating solution to the surface of the paper. The bulking agent used in the present invention is an agent capable of obtaining a pulp sheet having a lower degree of tension than an additive-free pulp sheet. The addition place of the bulking agent of the present invention is not particularly limited as long as it is before the step of applying the coating liquid to the surface of the paper, and specifically includes the dryer part, but it is added to the pulp slurry. It is preferred that Specifically, a place where blending with the pulp raw material is desirable, such as a refiner, a mixing chest, a machine chest, a fan pump, a head box, and the like. In addition, it is thought that the bulking agent of this invention remains on paper after adding to a pulp raw material, and it demonstrates that performance is added. The addition amount of the bulking agent of this invention is 0.01 to 10 weight% with respect to a pulp, and also 0.1% -5% by weight, in particular 0.2-2% by weight is preferred.

  Examples of the bulking agent include organosiloxanes, glyceryl ethers, quaternary ammonium salts, imidazole derivatives, amines, amides, esters, higher alcohols, and higher alcohols and ester alkylene oxide adducts. As the bulking agent, a compound that hydrophobizes the pulp surface is preferable. Esters include polyhydric alcohol fatty acid esters and polycarboxylic acid esters.

  The bulking agent used in the present invention has a melting point higher than the highest temperature of the coating solution used in the step of applying the coating solution to the paper surface (for example, the size press step and the coating step). The melting point is preferably 3 ° C. or higher, more preferably 5 ° C. or higher, more preferably 8 ° C. or higher, more preferably 10 ° C. or higher, and still more preferably 15 ° C. or higher. In other words, the highest temperature of the coating solution used in the step of applying the coating solution to the paper surface is lower than the melting point of the bulking agent, preferably 3 ° C. or more, more preferably 5 ° C. As described above, it is more preferably 8 ° C. or higher, more preferably 10 ° C. or higher, and further preferably 15 ° C. or higher. In the method for producing bulky paper of the present invention, a bulking agent having a melting point higher than the temperature of the coating liquid used in the step of applying the coating liquid to the paper surface is selected, and the temperature of the coating liquid used in the step is set. This is achieved by operating at a temperature lower than the melting point of the bulking agent.

  In the present invention, the melting point of the bulking agent is the temperature at which the active ingredient (including a plurality of cases) in the bulking agent starts to melt when measured with a melting point measurement device [MP-J3 manufactured by Yanagimoto Seisakusho Co., Ltd.]. And the average temperature at the end of melting. At that time, a sample of about 1 mg is heated at a temperature of about 1 ° C./min. The measurement is repeated three times, and average values are used for the temperature at which melting starts and the temperature at which melting ends. The temperature of the coating liquid is an average temperature when the coating liquid contacts the paper during operation.

(Paper making method)
LBKP was disaggregated and beaten with a beater at room temperature to obtain 2.2% LBKP slurry. The Canadian standard freeness of the slurry was 420 ml. The 2.2% LBKP slurry was weighed out so that the basis weight of the sheet after paper making was absolutely dry and 80 g / m ² , and cationized starch (CATO308, manufactured by NSC Japan) 0.5% ( Weight basis, vs. pulp, the same applies hereinafter), industrial sulfuric acid band 1.0%, alkenyl succinic anhydride sizing agent (Arakawa Chemical Industries, Ltd. size pine SA-862), bulking agent (Table 1) ) 1.0% (as an effective component), 0.015% of a cationic polyacrylamide yield improver (Percoll 47, manufactured by Ciba Specialty Chemicals) is added with stirring, and then the pulp concentration is 0.5%. Then, the mixture was diluted with water, and after stirring, the paper was made with a 150-mesh wire using a square-type tappi paper machine, and coated to obtain a wet paper. The wet paper after paper making was pressed with a press at 3.5 kg / cm ² for 5 minutes and dried at 105 ° C. for 2 minutes using a drum dryer. The dried paper was conditioned at 23 ° C. and a humidity of 50% for 1 day, and then the basis weight, tightness, and squeecht size of the paper were measured by the following methods. Furthermore, the size press liquid absorption was compared by the following method.

(Tensity)
The basis weight (g / m ² ) and thickness (mm) of the conditioned paper were measured, and the tightness (g / cm ³ ) was determined by the following formula.
Calculation formula: (tensity) = (basis weight) / (thickness) × 0.001

(Stick human sizing degree)
It measured according to JIS-P8122.

<Comparison of size liquid absorption amount>
A sizing solution was applied to a piece of paper obtained by cutting the paper obtained by the above papermaking method into 10 cm × 10 cm using a lab size press machine, and the liquid absorption was measured. The obtained results are shown in Table 2. The sizing liquid absorption was determined from the difference in weight of the paper pieces before and after the sizing liquid coating. The size press conditions are as shown below.
-Size solution: 6 wt% slurry of oxidized starch (Ace A, manufactured by Oji Cornstarch) was gelatinized by heating at 95 ° C for 30 minutes with stirring, and used at the temperatures shown in Table 3.
・ Lab size press: Kodak Nagase P-112 processor (500g size solution supplied)

-The above ester of the bulking agent 1 (esterification rate of about 40%) was used as a 2% ethanol solution.
-The ester of the bulking agent 2 (esterification rate of about 40%) was used as a 2% ethanol solution.
The polyamide polyamine of the bulking agent 3 is an epichlorohydrin reaction product of an amidation product of diethylenetriamine and a long chain fatty acid (Lunac S-40 manufactured by Kao Corporation), and the reaction product is used as a 2% aqueous dispersion. It was.

In Experimental Example 1, since the bulking agent 1 having a melting point of 53 ° C. was used, a large change was observed in the size liquid absorption at 45 to 50 ° C.
In Experimental Example 2, since the bulking agent 2 having a melting point of 70 ° C. was used, a large change was observed in the size liquid absorption at 65 to 70 ° C.
In Experimental Example 3, since the bulking agent 3 having a melting point of 73 ° C. was used, a large change was observed in the size liquid absorption at 60 to 65 ° C.
In Experimental Example 4, since no bulking agent was used, no increase in the size liquid absorption amount was observed at any temperature.

Claims (3)

One or more steps of applying the coating liquid to the paper surface after the dryer part; and a step of applying the bulking agent having a melting point higher than the temperature of the highest temperature of the coating liquid. A method for producing a bulky paper, comprising a step of previously incorporating the paper into a paper. The manufacturing method of Claim 1 which performs the application | coating process of the said coating liquid using a 2 roll type coating means. Furthermore, the manufacturing method of Claim 1 or 2 which has the process of making paper contain a sizing agent before the application | coating process of the said coating liquid.