JP4333991B2 - Stretched paper manufacturing method - Google Patents

Description

  The present invention relates to a method for producing stretched paper used as molding paper for three-dimensional molding by methods such as press molding, pressure molding, and vacuum molding.

  2. Description of the Related Art Conventionally, stretched paper having stretch properties has been used as a molded paper for containers such as food packaging materials and drinking water. This stretched paper is stretched by shrinking the paper by a method such as creping or kulpacking. Also, in recent years, as a method for producing stretched paper having higher stretch properties, a corrugated pre-form is applied, and a hard roll that has ribs on the surface and rotates at a high speed, and a slow and smooth surface. A technique has been proposed in which paper is condensed between a pair of rolls made of soft rolls that rotate at a speed to impart stretch characteristics simultaneously in the vertical and horizontal directions (see Patent Document 1).

However, the technique described in Patent Document 1 requires pre-corrugation of the corrugated processing form, and the manufacturing method is complicated. Also, the elongation characteristics are not sufficient, such as about 20% in length and 16% in width. It cannot cope with molding that requires characteristics. In view of such a situation, the present inventors have previously proposed a method for producing stretched paper in which high stretch properties exceeding the concept of conventional paper are easily contracted in the vertical and horizontal directions simultaneously (see Patent Document 2).
Japanese National Patent Publication No. 11-509276 Japanese Patent Laid-Open No. 2004-3071

  The stretched paper manufacturing method disclosed in Patent Document 2 is a method in which the peripheral speed of the soft roll is made slower than the peripheral speed of the hard roll, and the wet paper sheet is subjected to pressurization to simultaneously shrink the paper in the vertical and horizontal directions. The wet paper sheet interposed between the hard roll and the soft roll having grooves on the surface is subjected to the action of shearing force generated by the difference in peripheral speed between the hard roll and the soft roll, and the wet paper sheet is hard in the longitudinal direction. The roll is compressed in the trough portion of the roll and given longitudinal shrinkage, while the transverse direction is also drawn to the trough groove along with the compression in the longitudinal direction to give shrinkage, and acts on the wet paper sheet with sufficient shearing force. In order to achieve this, the frictional force of each interface of the hard roll / wet paper / soft roll must be maintained.

  In order to maintain the frictional force and increase the shrinkage imparting effect, the groove interval, depth, and groove shape of the hard roll are important factors because they affect the contact area with the wet paper, but the soft roll is also pressurized. -It becomes an important factor because it deforms by the shear force generated by the peripheral speed difference and compresses and deforms the wet paper web layer. It is important for soft rolls to efficiently propagate the deformation caused by stress to the paper layer of the wet paper sheet, and the compression elastic modulus, which is an indicator of it, is greatly involved. It is an essential requirement to specify the range of elastic modulus. However, since the material is basically soft, the surface of the soft roll becomes noticeable over time due to friction with the wet paper, and the wear powder of the worn soft material adheres to the wet paper surface that has been contracted and stretched. The utility value of paper is significantly impaired. Therefore, it is necessary to periodically stop the apparatus and clean the surface of the soft roll, and the productivity is significantly reduced. Further, since the wear powder is taken into the paper layer by a soot of wet paper generated by shrinkage application, so-called microcrepe, it is used for, for example, a paper base material or a film disclosed in JP-A-9-314072. There is a problem that even if a method of sliding the dust removing device against the surface of the stretched paper is adopted, it cannot be completely removed.

  As a result of intensive studies to solve such problems, the present inventors have found a method for efficiently removing the wear powder generated on the soft roll without transferring it to the wet paper sheet, and have completed the present invention. . That is, an object of the present invention is to provide a method for producing stretched paper that has no abrasion powder adhering to a soft roll and has an elongation characteristic of 20% or more in both the longitudinal and lateral directions, as defined by JIS P 8113. There is to do.

In order to achieve the above object, the invention described in claim 1 is composed of a hard roll provided with grooves along the roll circumferential direction at predetermined intervals in the roll width direction and a soft roll having a flat roll circumferential surface. A pair of press rolls is provided, and a wet paper sheet is passed through a shrinkage imparting device that rotates at a reduced pressure relative to the peripheral speed of the hard roll under pressure. In a method for producing stretched paper that is then dried.
An abrasion powder removing device is attached to the soft roll of the shrinkage imparting device, and the shrinkage is imparted to the wet paper sheet while removing the abrasion powder of the soft roll that is generated when the shrinkage of the wet paper sheet is imparted.

  According to a second aspect of the present invention, the abrasion powder removing device according to the first aspect rotates in sliding contact with the soft roll in the width direction to clean the brush roll and the brush roll that remove the abrasion powder from the surface of the soft roll. And a dust collection duct for collecting the abrasion powder removed by the brush roll.

  As described above, according to the stretched paper manufacturing method of the present invention, the abrasion powder removing device is attached to the soft roll of the shrinkage imparting device, and the abrasion powder of the soft roll generated when the wet paper sheet is imparted with the shrinkage is removed from the wear. Since the wet paper sheet is shrunk while being removed by the powder removing device, the abrasion powder generated from the soft roll can be removed before being transferred to the wet paper sheet to be processed. Even if it deteriorates with the passage of time due to frictional force, it is possible to stably produce stretched paper having an elongation of 20% or more in both longitudinal and lateral directions where no abrasion powder adheres.

  The wear powder removing device rotates in sliding contact with the soft roll in the width direction to remove the wear powder from the surface of the soft roll, an air nozzle for cleaning the brush roll, and the wear powder scraped off by the brush roll. The dust collecting duct collects the wear powder generated from the soft roll without leaving the surface of the soft roll with the brush roll, and the dust collected on the brush roll is washed with an air nozzle and collected. Since it can collect | recover in a dust duct, before transferring to the wet paper sheet to process, the abrasion powder which generate | occur | produces from a soft roll can be removed more reliably.

  The best mode for carrying out the stretched paper manufacturing method according to the present invention will be described below. FIG. 1 is a schematic configuration diagram showing an example of an embodiment of a paper machine for carrying out a method for producing stretched paper according to the present invention, and FIG. 2 is an outline of an abrasion powder removing device attached to a soft roll of a shrinkage imparting device of this example. FIG.

  In this example, the wet paper sheet 1A made in the previous process of the paper machine is preliminarily dried by a drying device 2 made of a cylinder dryer to adjust the moisture, and the wet paper sheet 1B having the moisture adjusted is desired by the shrinkage imparting device 3. The wet paper sheet 1C to which the shrinkage is applied is dried by a drying device 4 composed of a cylinder dryer, and smoothed by a calendar 5 to obtain stretched paper 1D.

  The shrinkage imparting device 3 includes a pair of press rolls including a hard roll 6 provided with grooves along the circumferential direction on the roll peripheral surface at a predetermined interval in the roll width direction, and a soft roll 7 having a flat roll peripheral surface. 8, a peripheral speed adjusting device (not shown) that adjusts the peripheral speed of the soft roll 7 to rotate slowly with respect to the peripheral speed of the hard roll 6 under pressure, a hard roll 6 and a soft roll 7, It is the structure provided with the pressure adjustment apparatus (not shown) which adjusts the linear pressure. And the abrasion powder removal apparatus 10 which removes the abrasion powder 9 of the soft roll 7 which generate | occur | produces at the time of the said shrink contraction | imparting of the wet paper sheet 1B is attached to the soft roll 7. FIG.

  This wear powder removing device 10 is in sliding contact with the width direction of the soft roll 7, rotates in the direction opposite to the rotation direction of the soft roll 7, and removes the wear powder 9 from the surface of the soft roll 7. The air nozzle 12 that blows air on the brush roll 11 to remove the wear powder 9 of the soft roll 7 that adheres to the brush roll 11 and cleans it, and the air that is removed by the brush roll 11 and blown off from the air nozzle 12 is blown away. The dust collecting duct 13 collects and collects the wear powder 9.

  The stretched paper according to the present invention is manufactured as follows.

  In the wet paper sheet 1A of the present invention, it is preferable that the raw material pulp to be used has a composition of 100% natural pulp from the viewpoint of waste treatment and environmental load as background of environmental problems. As natural pulp, coniferous or broad-leaved wood fibers, bast fibers such as trifoam and straw, non-wood fibers such as bagasse and kenaf, cotton fibers, and waste paper can be used. The wood fiber is preferred.

  As the paper machine in the present invention, a general paper machine such as a normal long-mesh multi-cylinder paper machine, a twin-wire type paper machine, or a round-mesh multi-cylinder paper machine can be used, but the shrinkage imparting device 3 of the present invention is a wet paper web. If it can be installed between the drying device 2 that can adjust the moisture in the sheet 1A in the range of 20 to 50%, preferably 30 to 40%, and the drying device 4 that can dry the moisture in the paper to about 3 to 10%, There is no particular limitation.

In the shrinkage imparting device 3, the linear pressure between the hard roll 6 and the soft roll 7 is adjusted by the pressure adjusting device, and the peripheral speed of the soft roll 7 is slower than the peripheral speed of the hard roll 6 by the peripheral speed adjusting device. It is a pair of press rolls 8 adjusted so that the wet paper sheet 1B adjusted by the drying device 2 is passed through the paper to a moisture content of 20 to 50%. Here, the wet paper sheet 1 </ b> B is subjected to the action of a shearing force generated by the difference in peripheral speed between the hard roll 6 and the soft roll 7. As a result, in the longitudinal direction of the wet paper sheet 1B, the paper layer corresponding to the peripheral speed difference is compressed and longitudinal contraction is applied. On the other hand, in the lateral direction, the paper layer is pushed into the groove of the hard roll 6 along with the compression due to the difference in peripheral speed, and lateral contraction is applied. Thereafter, the wet paper sheet 1C to which shrinkage is imparted is dried by the drying device 4 until the moisture in the paper becomes about 3 to 10%. As a result, it is possible to obtain stretched paper 1D having a basis weight of 100 to 400 g / m ² and a tensile breaking elongation defined in JIS P 8113 of 20% or more in both the vertical and horizontal directions.

  In order to easily manufacture stretched paper 1D having high stretch properties, the moisture of wet paper sheet 1B that passes through shrinkage imparting device 3 is an element that affects the plasticity of wet paper sheet 1B as described above, and In the present invention, the moisture in the paper of the wet paper sheet 1B is preferably adjusted to 20 to 50%. If the moisture in the paper is higher than 50%, the frictional force is lowered and sufficient shrinkage is not imparted. Conversely, if it is lower than 20%, the wet paper sheet 1B is inferior in plasticity and the shrinkage imparting effect is lowered. Further, when the moisture in the paper is low, the frictional force between the soft roll 7 and the wet paper sheet 1B increases, and the surface wear of the soft roll 7 is likely to proceed, so the moisture in the paper is in the range of 20 to 50%. It is important to adjust.

  The soft roll 7 is a material capable of obtaining a frictional force that generates a shearing force sufficient to impart shrinkage to the wet paper sheet 1B, and includes polyurethane rubber, chloroprene rubber, nitrile butadiene rubber, silicone. Although rubber, nitrile rubber, polysulfide rubber, epichlorohydrin rubber, etc. can be used, it is preferable that the material has a wear resistance of 0.5 cc or less and a compressive deformation amount of 5% or more. When the wear resistance exceeds 0.5 cc, the soft roll 7 is significantly worn in the shrinkage imparting process, and it is difficult to remove the wear powder 9 even with the wear powder removing apparatus 10 of the present invention. Further, when the amount of compressive deformation is less than 5%, a shearing force sufficient to impart shrinkage to the wet paper sheet 1B cannot be obtained. In the present invention, the wear resistance is the wear loss (cc) according to the wear test method specified in JIS K 7204, and the compression deformation is the compressive strain rate (%) according to the compression test specified in JIS K 6301. It is a representation.

  As described above, the wear powder removing device 10 includes the brush roll 11 slidably contacted in the width direction of the soft roll 7, the air nozzle 12 for cleaning the wear powder 9 of the soft roll 7 by the brush roll 11, and the brush roll. The dust collecting duct 13 collects and collects the wear powder 9 removed by the dust 11.

  The diameter of the brush roll 11 is not particularly limited, but an outer diameter in the range of 100 to 250 mm is suitable for installing the apparatus. Further, the brush bristles 11a of the brush roll 11 may be made of general-purpose brush hairs 11a having a material, a thickness and a length that can efficiently remove the wear powder from the surface of the soft roll 7 and do not damage the soft roll 7. A brush roll 11 in which synthetic resin fibers are planted on the entire outer surface of the brush shaft roll with a length of 20 to 40 mm is suitable. In addition, rotating the brush roll 11 at a rotational speed of 100 to 500 rpm in the direction opposite to the rotation of the soft roll 7 is optimal for removing the wear powder 9 adhering to the surface of the soft roll 7. In order to prevent the removed wear powder 9 from scattering, it is preferable to operate at a rotational speed of 500 rpm or less.

  Further, the pressure applied to the hard roll 6 and the soft roll 7 of the shrinkage imparting device 3, the contact area at the time of pressurization, the peripheral speed difference, the shape of the groove provided in the hard roll 6, etc. In addition to being an important element for imparting shrinkage to the wet paper sheet 1B by the shearing force generated between the two, it is also an element that affects the wearability of the soft roll 7.

  In the shrinkage imparting device 3 of the present invention, the grooves provided in the hard roll 6 are spaced from 1.0 mm to 1.5 mm in the roll width direction, with a groove width of 0.7 mm to 1.2 mm and a groove depth of 0. It is preferably a shape formed in a range of 5 mm to 1.5 mm.

  Furthermore, the pressurization between the hard roll 6 and the soft roll 7 is preferably in the range of 10 kg / cm to 100 kg / cm, more preferably 10 kg / cm to 70 kg / cm. The circumferential speed difference between the hard roll 6 and the soft roll 7 is preferably rotated within the range of 0.60 or more and 0.75 or less when the circumferential speed of the hard roll 6 is 1. By passing the wet paper sheet 1B between the hard roll 6 and the soft roll 7 rotating with the difference in peripheral speed under the pressure, a shear force necessary and sufficient to impart shrinkage to the wet paper sheet 1B is generated. Can be made. Pressurization exceeding the linear pressure of 70 kg / cm or rotating the peripheral speed of the soft roll 6 below 0.60 relative to the peripheral speed of the hard roll 5 will accelerate the wear of the soft roll 6. .

  EXAMPLES Hereinafter, although an Example demonstrates this invention in detail, this invention is not limited at all by this. The characteristics of stretched paper according to the following examples and comparative examples are shown in the table.

[Example 1]
General purpose softwood bleached kraft pulp (NBKP) beaten up to 300 ml of Canadian standard freeness (CSF) is used as raw pulp, and the set basis weight on the wire is 150 g / m ² with a normal multi-cylinder dryer type long net paper machine. A wet paper sheet 1A was made. The shrinkage imparting device 3 was installed between the former drying device 2 and the latter drying device 4. The shrinkage imparting device 3 has a V-shaped shape having a groove interval of 1.25 mm, a groove width of 0.9 mm, and a groove depth of 0.65 mm, and a diameter made of stainless steel provided with grooves along the circumferential direction in the roll width direction. This is a press roll 8 comprising a 500 mm hard roll 6 and a soft roll 7 having a diameter of 560 mm coated with a nitrile butadiene rubber having a wear resistance of 0.3 cc and a compressive deformation amount of 8% to a thickness of 30 mm for the outer layer.

  The soft roll 7 has a brush roll 11 having a diameter of 200 mm that slides in the width direction, an air nozzle 12 that removes the wear powder 9 from the brush roll 11, and a dust collection duct 13 that collects the removed wear powder 9. A device 10 is installed. The brush roll 11 is planted on the entire surface of the brush shaft roll so that a polypropylene fiber having a thickness of 0.4 mm has a length of 40 mm of the brush bristles 11 a, and rotates at a rotational speed of 200 rpm in the opposite direction to the soft roll 7. Yes.

Between the hard roll 6 and the soft roll 7 constituting the press roll 8, the wet paper sheet 1B having the moisture content in the paper adjusted to 35% is passed through the preceding drying device 2 and pressurized at a linear pressure of 30 kg / cm. Then, a wet paper sheet 1C provided with shrinkage by setting the circumferential speed of the soft roll to 70% of the circumferential speed of the hard roll 6 was obtained. Then, it dried until the moisture in paper became 6% with the drying apparatus 4 of the back | latter stage, the calendar process was given with the calendar | calender 5 of 20 kg / cm of linear pressure, and the extending | stretching paper 1D with a basic weight of 200 g / m < ² > was obtained.

  The wear resistance of the soft roll 7, the amount of compressive deformation, and the physical properties of stretched paper were evaluated by the following methods.

<Abrasion resistance> According to the abrasion test method prescribed | regulated to JISK7204, the abrasion loss capacity (cc) of the soft roll raw material test piece was measured.

<Compression deformation amount> According to the compression test method defined in JIS K 6301, a soft roll material test piece having a cross-sectional area of 3000 mm ² and a thickness of 10 mm was pressed at a speed of 10 mm per minute, and the compression force was 0.5 MPa. The amount of deformation was determined by compressive strain rate (%).

<Elongation at break> Measured according to JIS P8113.

<Abrasion powder adhering to sheet> Visual evaluation was performed.

[Comparative Example 1]
Extensive paper 1D having a basis weight of 200 g / m ² was obtained in the same manner as in the example except that the abrasion powder removing device 10 was installed after the shrinkable wet paper sheet 1C passed through the drying device 4.

[Comparative Example 2]
For the soft roll 7 of the shrinkage imparting device 3, a soft roll having an outer diameter of 550 mm coated with a nitrile butadiene rubber having a wear resistance of 0.1 cc and 5% compression deformation to a thickness of 25 mm is used. Extensive paper 1D was obtained in the same manner as in Example, except that no abrasion powder removing device was installed.

  The stretched paper 1D obtained in the examples and comparative examples has an intended longitudinal and lateral elongation characteristic of 20% or more. However, even in Comparative Example 2 in which the wearability of the soft roll 7 was improved, the generation of wear powder 9 was inevitable with the lapse of treatment time, and the appearance of the product was significantly impaired. Further, since the abrasion powder 9 adhering to the surface of the stretched paper base material bites into the paper layer by the microcrepe generated by the shrinking treatment as described above, the base of the stretched paper as in Comparative Example 1 is used. It could not be completely removed from the surface of the material. On the other hand, according to the Example by this invention, the abrasion powder 9 which generate | occur | produced could be removed before transferring to the wet paper sheet 1B to which shrinkage processing was carried out, and the expansion | extension paper which the abrasion powder 9 does not adhere was obtained.

It is a schematic block diagram which shows an example of embodiment of the paper machine which implements the manufacturing method of the stretched paper which concerns on this invention. It is a schematic structure sectional view of the abrasion powder removal device installed in the soft roll of the contraction imparting device of this example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1A Wet paper sheet 1B Wet paper sheet 1C which adjusted water | moisture content Shrink-processed wet paper sheet 1D Stretch paper 2 Drying device 3 Shrinkage imparting device 4 Drying device 5 Calendar 6 Hard roll 7 Soft roll 8 Press roll 9 Wear powder 10 Wear powder removal apparatus 11 Brush roll 11a Brush hair 12 Air nozzle 13 Dust collection duct

Claims (2)

It comprises a pair of press rolls composed of a hard roll having grooves along the roll circumferential direction at predetermined intervals in the roll width direction and a soft roll with a flat roll circumferential surface, and the peripheral speed of the hard roll is adjusted under pressure. In contrast, in the method for producing stretched paper, the wet paper sheet is shrunk by passing the wet paper sheet through a shrinkage imparting device that rotates at a lower peripheral speed of the soft roll, and then dried.
Wear paper removing device is attached to the soft roll of the shrinkage imparting device, and the wet paper sheet is shrunk and applied while removing the soft roll abrasion powder generated when the wet paper sheet is shrunk. Method.   The wear powder removing device rotates in sliding contact with the soft roll in the width direction to collect the wear powder scraped off by the brush roll, the air nozzle for cleaning the brush roll, and the brush roll for removing the wear powder from the surface of the soft roll. 2. The method for producing stretched paper according to claim 1, comprising a dust collecting duct.

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