JP4808665B2 - Process paper - Google Patents

Description

  The present invention relates to a process paper having releasability, and particularly to a process paper used in a process involving heat treatment at 200 to 230 ° C.

  Process paper used in the process of manufacturing sheet-like molded products such as synthetic resins and ceramics is a material that holds a fluid raw material as a support, and after being subjected to various treatments, is peeled off from the product. It is. Therefore, peelability, dimensional stability, surface smoothness, etc. are required. In particular, in the case of undergoing a heat treatment step, a problem occurs if there is a dimensional change or curl due to heat. Among the dimensional changes, particularly shrinkage becomes a problem in terms of quality including wrinkled surface defects. In addition to quality problems such as product deformation, curling leads to poor operability such as exfoliation work.

  Conventionally, as such process paper, those based on polyethylene laminated paper and those based on glassine paper have been used. However, in the case of polyethylene laminated paper, there are many problems in heat resistance, and in the case of glassine paper, dimensional change due to moisture absorption, curling, and surface smoothness reduction are problems.

In addition, the process paper for this application is not used once, but is generally used again after being wound up, and durability for multiple use is also required. A paper with a high inorganic pigment content in the base paper has also been proposed, but there is a drawback that it is easy to break the paper when it is reused because a decrease in strength is inevitable. Conversely, a process paper having a combustion ash content of 3% has been proposed for the purpose of improving dimensional stability (see, for example, Patent Document 1), but the effect of suppressing thermal shrinkage was insufficient.
JP 2005-314859 A

  An object of the present invention is to provide a process paper that is used in a heat treatment process at 200 to 230 ° C., has a repeated durability several times, and has no adverse effects on operability and quality due to shrinkage and curling. is there.

As a result of intensive studies to solve the above-mentioned problems, the following present invention has been found. That is, a process paper formed by providing a release layer on the base paper, on the basis weight of 130~170g / ^{m 2} base paper, coating a coating liquid containing a silicone-based material 12.5~25g / ^{m 2} It is applied in an amount, held at 120 to 150 ° C. for 15 seconds or more and dried to provide a release layer, and further coated with water or water-soluble resin or steam and then dried at 120 to 180 ° C. The curl correction was performed, and the shrinkage rate when the process paper was transferred from a 23 ° C. and 50% relative humidity environment to a 200 ° C. dryer and held for 2 minutes was 1.0% or less in the transverse direction, and the longitudinal direction. the Ri der 0.5%, and 23 ° C. of the casting paper, 50% relative humidity environment and 200 ° C. oven Karl immediately and held for 2 minutes is not more than ± 20 mm (plus ± here It means when warping the peeled surface side, minus is The release processed surface means if warped opposite side) that is a step paper characterized by.

  Further, in the process paper, the release layer is provided by applying and drying an aqueous coating liquid, and the shrinkage rate in the horizontal direction of the base paper in the application and drying process is 0.5% or more.

  Further, the process paper is characterized in that the combustion ash content of the base paper is 2% or less.

  With the process paper according to claim 1, product defects due to shrinkage of the process paper are suppressed.

With the process paper according to claim 2, a process paper excellent in terms of production cost can be obtained.

The process paper according to claim 3 provides a process paper that is further excellent in strength and suitable for repeated use.

  The present inventor has studied to suppress wrinkle-like defects on the product surface caused by thermal shrinkage of the process paper in the heat treatment process at 200 to 230 ° C. As a result, the shrinkage rate when the process paper is transferred from a 23 ° C. and 50% relative humidity environment to a 200 ° C. dryer and held for 2 minutes is 1.0% or less in the horizontal direction and 0.5% in the vertical direction. It was found that the wrinkle-like defects are hardly understood if the following are used. Further, the shrinkage rate when transferred to a 200 ° C. dryer from an environment of 23 ° C. and 50% relative humidity and held for 2 minutes is 1.0% or less in the horizontal direction and 0.5% or less in the vertical direction. It has been found that the adjustment can be achieved by a method of sufficiently heat-shrinking in advance in the process paper manufacturing process, alone or in combination.

  Water-soluble resin and emulsion used for the method of applying or impregnating paper-based process paper with water-soluble resin, emulsion, etc. As the emulsion, polyvinyl alcohol (PVA), other modified PVA, polyvinyl pyrrolidone, starch, modified starch, etc. Cellulose derivatives such as starch, carboxymethyl cellulose, hydroxyethyl cellulose, methyl cellulose, casein, gelatin, maleic anhydride resin, conjugated diene copolymer latex such as styrene-butadiene copolymer, methyl methacrylate-butadiene copolymer, acrylic ester And acrylate polymers or copolymers, acrylic polymer emulsions such as acrylic acid and methacrylic acid polymers or copolymers, and vinyl systems such as ethylene vinyl acetate copolymers Such as the combined emulsion and the like.

  As a condition for sufficiently heating and shrinking in advance in the process paper manufacturing process, in the present invention, the effect was observed by holding in a 150 ° C. hot air dryer for 15 seconds or more. This is confirmed in the process paper having a basis weight of 130 to 170 g / m <2>, and in the case of a lower basis weight, the object is achieved by the treatment with a lower heat amount. In the present invention, the object is achieved by causing thermal shrinkage of 0.2% or more, more preferably 0.5% or more in the transverse direction by the same treatment.

  As a method for suppressing curling, a generally used curling correction method, that is, water or water-soluble resin coating, correction by steam, or the like is preferably used. In terms of curl, the surface on which a sheet edge is raised on a horizontal table is called a plus curl surface, and the opposite surface is called a minus curl surface. Curling correction by coating is performed by applying water or a water-soluble resin to the negative curled surface and drying and shrinking it.

  Since the process paper of this invention is repeatedly used in the process of 200-230 degreeC, the strength reduction by a heat | fever is unpreferable. With regard to thermal discoloration, moderate discoloration is not a particular problem, but rather serves as a measure of thermal degradation. However, a very significant discoloration is not preferable because it causes defects or hinders defect detection. For these reasons, the base paper used preferably has a paper surface pH of 5 or more and less than 8. When it is higher or lower than this pH range, the strength is reduced by heat, which is not preferable.

  In order to obtain strength and dimensional stability necessary for use, it is preferable that NBKP (coniferous bleached kraft pulp) is blended in an amount of 10 to 50% by mass as a pulp blend of the base paper. If it is less than this range, the tensile strength, tear strength, dimensional stability, etc. tend to be inferior. On the other hand, when the amount is larger than this range, the formation of the base paper tends to be deteriorated, which adversely affects the release characteristics and release surface quality. Moreover, dimensional stability and formation can be obtained with good balance by setting the freeness (CSF) to 300 to 500 ml. Rough beating exceeding this range is not preferable because the formation of the base paper tends to deteriorate and adversely affects the release characteristics and release surface quality. A fine beating within this range is not preferable because the base sheet tends to have a high expansion / contraction rate, resulting in poor dimensional stability.

  Although it does not specifically limit as a peeling layer of this invention, Application | coating of a silicone type substance can be used preferably. Examples of the silicone-based coating include general solvent systems, solvent-free systems, and aqueous emulsion systems, and any of them can be preferably used. In general, it is said that the solvent-based and solvent-free systems have a wider range of control over the peeling performance, and there are many applications, but in the use of the present invention, the target quality can be obtained using an aqueous emulsion system. There are few restrictions on the coating device, and processing by aqueous coating that is excellent in terms of environment can be used.

  Base paper used for the process paper of the present invention includes heavy calcium carbonate, light calcium carbonate, calcium carbonate such as chalk, kaolin, calcined kaolin, pyrophyllite, sericite, talc and other silicic acids, titanium oxide, etc. Organic pigments such as inorganic fillers and urea resins may also be included. However, from the viewpoint of strength in repeated use at high temperatures, it is preferable that the filler content is low, and it is particularly good when the combustion ash content of the process paper is 2% or less.

  The process paper of the present invention may be calendered for the purpose of improving surface smoothness.

  EXAMPLES Hereinafter, although an Example and a comparative example are given and this invention is demonstrated more concretely, this invention is not limited by this.

(Base paper 1)
After mixing the pulp mixed so that LBKP is 90 mass% and NBKP 10 mass% in mass ratio to 400 mL of freeness (CSF), each chemical was blended into the pulp slurry according to the following formulation to prepare a paper slurry. .

(Formulation 1)
Alkyl ketene dimer emulsion to 0.2% by weight of pulp
Cationic starch to 0.9% by weight of pulp

Using the slurry, paper making was performed with a long web paper machine so that the basis weight was 160 g / m ² . In the size press, chemicals having the following formulation were adhered so as to have an absolutely dry adhesion amount of 1.5 g / m ² .
(Size press combination)
PAM surface paper strength agent 1 part by weight oxidized starch 1 part by weight water 98 parts by weight

In this way, base paper 1 (combustion ash content 0.5 mass%) was obtained.

(Base paper 2)
A base paper 2 (combustion ash content 0.5% by mass) was obtained in the same manner as the base paper 1 except that the pulp mixed so that the mass ratio was LBKP 50% by mass and NBKP 50% by mass was used.

(Base paper 3)
A base paper 3 (combustion ash content 0.5 mass%) was obtained in the same manner as the base paper 1 except that the pulp composition was LBKP 100 mass%.

(Base paper 4)
A base paper 4 (combustion ash content 0.5% by mass) was obtained in the same manner as the base paper 1 except that the pulp mixed so that LBKP was 40% by mass and NBKP 60% by mass was used.

(Base paper 5)
A base paper 5 (combustion ash content 0.5% by mass) was obtained in the same manner as the base paper 1 except that the freeness (CSF) of the pulp was beaten to 600 ml.

(Base paper 6)
A base paper 6 (combustion ash content 0.5% by mass) was obtained in the same manner as the base paper 1 except that the freeness (CSF) of the pulp was beaten to 300 ml.

(Base paper 7)
After beating the pulp mixed so that LBKP is 90 mass% and NBKP 10 mass% in mass ratio to a freeness (CSF) of 400 ml, according to the following formulation, each chemical was blended into the pulp slurry to prepare a paper slurry. .

(Formulation 2)
Alkyl ketene dimer emulsion to 0.2% by weight of pulp
Cationic starch to 0.9% by weight of pulp
Light calcium carbonate 3.0% by mass of pulp

Using the slurry, paper making was performed with a long paper machine to a basis weight of 160 g / m ² . In the size press, the same chemical as the base paper 1 was adhered. In this way, base paper 7 (combustion ash content 2.0 mass%) was obtained.

(Base paper 8)
After beating the pulp mixed so that LBKP is 90 mass% and NBKP 10 mass% in mass ratio to a freeness (CSF) of 400 ml, according to the following formulation, each chemical was blended into the pulp slurry to prepare a paper slurry. .

(Formulation 3)
Alkyl ketene dimer emulsion to 0.2% by weight of pulp
Cationic starch to 0.9% by weight of pulp
Light calcium carbonate 7.0% by mass of pulp

Using the slurry, paper making was performed with a long paper machine so that the basis weight was 160 g / m ² . In the size press, the same chemical as the base paper 1 was adhered. In this way, base paper 8 (combustion ash content 5.0 mass%) was obtained.

Example 1
The following coating solution 1 was applied to base paper 1 so that the absolutely dry solid content was 2.0 g / m ² .
(Coating fluid 1)
Aqueous silicone emulsion (solid content 40%) 5 mass parts polyvinyl alcohol aqueous solution (solid content 10%) 100 mass parts water 45 mass parts

  This was held in a 150 ° C. hot air dryer for 15 seconds and dried, and then water was applied to the opposite side, followed by drying in a 180 ° C. hot air dryer to give curl correction, and a process paper of Example 1 was obtained. .

Reference example 2
A process paper of Reference Example 2 was obtained in the same manner as in Example 1 except that no curling was corrected by water coating on the reverse side.

Example 3
The following coating liquid 2 was applied to the base paper 1 so that the dry solid content was 2.0 g / m ² .
(Coating fluid 2)
Heavy release silicone 10 parts by weight Toluene 100 parts by weight

  This was held in a 150 ° C. hot air dryer for 15 seconds and dried, and then water was applied to the opposite side, followed by drying with a 180 ° C. hot air dryer to give curl correction, and a process paper of Example 3 was obtained. .

Example 4
The same coating liquid 1 as in Example 1 was applied to the base paper 1 so that the absolute dry solid content was 1.0 g / m ² .

  This was held in a 120 ° C. hot air drier for 15 seconds and dried, and then water was applied to the opposite side, followed by drying with a 120 ° C. hot air drier and curl correction to obtain a process paper of Example 4. .

Example 5
Base paper 1 was impregnated with silanol-modified PVA so as to have an absolute dry solid content of 1.5 g / m ² with a tab size press, and dried with a 120 ° C. hot air drier.

The same coating liquid 1 as in Example 1 was applied to this so that the absolutely dry solid content was 1.0 g / m ² .

  After holding it in a 120 ° C. hot air dryer for 15 seconds and drying, it was further coated with water, dried with a 120 ° C. hot air dryer and subjected to curl correction to obtain a process paper of Example 5. .

Example 6
A process paper of Example 6 was obtained in the same manner as in Example 1 except that the base paper 2 was used instead of the base paper 1.

Example 7
A process paper of Example 7 was obtained in the same manner as in Example 1 except that the base paper 3 was used instead of the base paper 1.

Example 8
The process paper of Example 8 was obtained like Example 1 except having used the base paper 4 instead of the base paper 1. FIG.

Example 9
A process paper of Example 9 was obtained in the same manner as in Example 1 except that the base paper 5 was used instead of the base paper 1.

Example 10
A process paper of Example 10 was obtained in the same manner as in Example 1 except that the base paper 6 was used instead of the base paper 1.

Example 11
A process paper of Example 11 was obtained in the same manner as in Example 1 except that the base paper 7 was used instead of the base paper 1.

Example 12
A process paper of Example 12 was obtained in the same manner as in Example 1 except that the base paper 8 was used instead of the base paper 1.

Comparative Example 1
The same coating liquid 1 as in Example 1 was applied to the base paper 1 so that the absolute dry solid content was 1.0 g / m ² .

  This was held in a hot air dryer at 105 ° C. for 15 seconds and dried, and then water was applied to the opposite side, followed by drying in a hot air dryer at 105 ° C. to curl correction to obtain a process paper of Comparative Example 1. .

Regarding the process papers of Example 1 , Examples 3 to 12, Reference Example 2 , and Comparative Example 1 obtained as described above, (1) moved from 23 ° C. and 50% relative humidity to a 200 ° C. drier. Shrinkage when held for a minute (horizontal direction, longitudinal direction; indicated as shrinkage rate 1 in the table), (2) curl in a 23 ° C., 50% relative humidity environment and immediately after holding for 2 minutes in a 200 ° C. drier ( Cut to A4 size and place on a flat table, and the height is expressed in mm when the paper edge warps from the table. Description), (3) Shrinkage rate in the horizontal direction of the base paper in the coating and drying step (100 × (base paper width−width after processing) / base paper width; indicated as shrinkage rate 2 in the table) is shown below.

  A vinyl chloride paste was applied on each process paper and cured by heat treatment at 200 ° C. for 2 minutes. The obtained polyvinyl chloride sheet was peeled from the process paper, and the surface state (surface quality) was visually evaluated.

Example 1: A PVC sheet with good surface quality was obtained. Peeling workability was also good. Although it was used repeatedly 5 times, the performance as a process paper was not deteriorated.

Reference Example 2: Although a surface quality unevenness due to the shrinkage of the process paper was slightly observed, a surface quality PVC sheet having no practical problem was obtained. The peeling workability was not preferable because of strong curl. Although it was used repeatedly 5 times, the performance as a process paper was not deteriorated.

Example 3: A PVC sheet with good surface quality was obtained. Peeling workability was also good. Although it was used repeatedly 5 times, the performance as a process paper was not deteriorated. Due to the solvent-based silicone coating, the coating equipment was limited.

Example 4: Although the surface unevenness due to the shrinkage of the process paper was slightly strong, a surface-quality PVC sheet having no practical problem was obtained. Peeling workability was also good. Although it was used repeatedly 5 times, the performance as a process paper was not deteriorated.

Example 5: Although some surface quality unevenness due to the shrinkage of the process paper was observed, a surface quality PVC sheet having no practical problem was obtained. The peeling workability was not very favorable due to curling, but there was no problem in practical use. Although it was used repeatedly 5 times, the performance as a process paper was not deteriorated.

Example 6: Since the base paper formation was slightly inferior, the surface quality was slightly poor, but there was no problem in practical use. The peeling work was good. Although it was used repeatedly 5 times, the performance as a process paper was not deteriorated.

Example 7: A PVC sheet with good surface quality was obtained. Peeling workability was also good. Although it was used repeatedly 5 times, no deterioration in performance as a process paper was observed, but a decrease in strength was observed, and the process paper was easily torn during the paper passing operation. However, there was no problem in practical use.

Example 8: The surface quality was poor because the base paper formation was considerably inferior, but practically no problem. The peeling work was good. Although it was used repeatedly 5 times, the performance as a process paper was not deteriorated.

Example 9: Since the base paper formation was slightly inferior, the surface quality was slightly poor, but there was no problem in practical use. The peeling work was good. Although it was used repeatedly 5 times, the performance as a process paper was not deteriorated.

Example 10 Although a surface quality unevenness due to the shrinkage of the process paper was slightly strong, a surface-quality PVC sheet having no practical problem was obtained. Peeling workability was also good. Although it was used repeatedly 5 times, the performance as a process paper was not deteriorated.

Example 11: A PVC sheet with good surface quality was obtained. Peeling workability was also good. Although it was used repeatedly 5 times, the performance as a process paper was not deteriorated.

Example 12: A PVC sheet with good surface quality was obtained. Peeling workability was also good. Although it was used repeatedly 5 times, the performance as a process paper was not deteriorated. Although a slight decrease in strength was observed, there was no practical problem.

Comparative Example 1: Wrinkled defects due to thermal shrinkage of the process paper were observed. Other items were the same as in Example 1.

  The process paper of the present invention is less susceptible to shrinkage and strength reduction in the heat treatment process at 200 to 230 ° C., and can be preferably used for repeated use in the same process.

Claims (3)

A process paper formed by providing a release layer on the base paper, on the basis weight of 130~170g / ^{m 2} base paper, a coating liquid containing a silicone-based material at a coverage of from 12.5~25g / ^{m 2} Apply, hold at 120-150 ° C for 15 seconds or more and dry to provide a release layer, and after applying water or water-soluble resin coating or steam, dry at 120-180 ° C. The curl correction was performed, and the shrinkage when the process paper was transferred to a 200 ° C. dryer from a 23 ° C. and 50% relative humidity environment for 2 minutes was 1.0% or less in the horizontal direction and 0 in the vertical direction. .5% der less is, and 23 ° C. of the casting paper, a relative humidity of 50% environment and 200 ° C. oven Karl immediately and held for 2 minutes is not more than ± 20 mm (plus ± herein exfoliated It means the case of warping to the surface side, minus is the peeled surface Casting paper, characterized in meaning) that the case where warped opposite side. 2. The process paper according to claim 1 , wherein the release layer is provided by applying and drying an aqueous coating liquid, and a shrinkage ratio in a transverse direction of the base paper in the application and drying process is 0.5% or more. The process paper according to claim 1 or 2 , wherein the combustion paper has a combustion ash content of 2% or less.