JP2017036521A - Heat seal paper and manufacturing method therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a heat seal paper having reduced powder falling of powder fine particles during use as a pod filter and proper extractability and excellent in working efficiency, mechanical strength and heat sealability when exchanging the pod filter in a coffee maker facility and a simple and efficient manufacturing method therefor.SOLUTION: There are provided a heat seal paper by wet paper making a raw material pulp slurry prepared from a fiber mixture containing a kraft pulp fiber and synthetic fiber, where the synthetic fiber contains a polypropylene fiber having a core sheath structure, a polyethylene terephthalate fiber having a core sheath structure and a polyethylene terephthalate fiber having no core sheath structure and a ratio between tensile elongation in a width direction CDand tensile elongation in a lengthwise direction MDaccording to JIS P 8116, CD/MDis 1.10 or more and a ratio between wet tensile elongation in the width direction CDand wet tensile elongation in the lengthwise direction MDaccording to JIS P 8135, CD/MDis 1.00 or more, and a manufacturing method therefor.SELECTED DRAWING: None

Description

  The present invention relates to a heat seal paper used for, for example, a coffee filter and a method for producing the same.

  For example, sheet paper made from natural pulp fibers such as kraft pulp and hemp pulp and synthetic fibers such as polyethylene and polypropylene has been used as food filter paper such as coffee filter paper. A sheet paper made only from the synthetic fiber is also proposed.

  Patent Document 1 discloses an extraction in which a paper in which a polyetheramide compound is attached to a sheath-core type composite fiber having ethylene copolymer-modified polypropylene as a sheath component and propylene as a core component, and a hydrophilic fiber are mixed and made by paper. Sheet paper is disclosed.

  In Patent Document 2, a non-woven fabric containing a core-sheath composite fiber or a fibrillated core-sheath composite fiber having a core part of an ethylene copolymer having a melting point in a specific range and a sheath part of a composition of aliphatic polyester and polyolefin is heated. A tea bag having a sealing layer is disclosed.

JP-A-11-169296 JP 2010-275676 A

  In the present invention, for example, coffee powder is reduced in powder dust when used as a pod filter for coffee, and has an appropriate extractability, and work efficiency required when replacing a pod filter in a coffee maker facility Another object of the present invention is to provide a heat-sealing paper excellent in mechanical strength and heat-sealability, and a simple and efficient production method for the heat-sealing paper.

The present invention
A raw pulp slurry prepared from a fiber mixture containing a mixture of kraft pulp fiber and synthetic fiber is wet-papered,
The synthetic fiber mixture includes a polypropylene fiber having a core-sheath structure, a polyethylene terephthalate fiber having a core-sheath structure, and a polyethylene terephthalate fiber having no core-sheath structure,
The ratio (CD ₁ / MD ₁ ) between the tensile elongation (CD ₁ ) in the transverse direction and the tensile elongation (MD ₁ ) in the longitudinal direction obtained according to JIS P 8116 is 1.10 or more, and JIS P The heat seal paper having a ratio (CD ₂ / MD ₂ ) of the wet tensile elongation in the transverse direction (CD ₂ ) and the wet tensile elongation in the longitudinal direction (MD ₂ ) obtained in accordance with 8135 of 1.00 or more. About.

The present invention also provides
A method for producing the heat-seal paper,
Preparing a raw pulp slurry from the fiber mixture;
A process of wet-making the raw pulp slurry with a paper machine equipped with a circular net and a slanted short net to produce a heat-sealed base paper,
The present invention relates to a method for producing heat-sealed paper, comprising a step of performing heat treatment on one side of the heat-sealed base paper with a heat calendar.

In the present invention, for example, coffee powder is reduced in powder dust when used as a pod filter for coffee, and has an appropriate extractability, and work efficiency required when replacing a pod filter in a coffee maker facility Excellent mechanical strength and heat sealability. Further, such a heat-sealed paper can be easily and efficiently produced by the production method of the present invention.

(Embodiment)
The heat-sealed paper of the present invention is made from a fiber mixture containing kraft pulp fibers and a mixture of synthetic fibers.

  Kraft pulp usually used in the field of food filters can be used as the kraft pulp fiber. Examples of the kraft pulp include chemical pulps such as softwood unbleached kraft pulp (NUKP), softwood bleached kraft pulp (NBKP), hardwood unbleached kraft pulp (LUKP), and hardwood bleached kraft pulp (LBKP). Are used alone or in admixture of two or more. Among these, when heat-sealing heat-sealing paper, it has a great effect of preventing fibers from adhering to the heat-sealing device, and improves mechanical strength and suppresses tensile elongation and wet tensile elongation. In particular, softwood bleached kraft pulp (NBKP) is preferably used because of its great effect.

  The freeness (CSF) based on JIS P 8121-2 of the kraft pulp is not particularly limited, and may be adjusted to, for example, about 400 to 650 ml. Furthermore, it is preferable to adjust to 450-550 ml from the point that the improvement in mechanical strength and the effect of suppressing tensile elongation and wet tensile elongation are large.

  The synthetic fiber mixture includes a polypropylene (hereinafter also referred to as PP) fiber having a core-sheath structure, a polyethylene terephthalate (hereinafter also referred to as PET) fiber having a core-sheath structure, and a PET fiber having no core-sheath structure. Is included.

  The PP fiber having the core-sheath structure can impart heat-sealing properties, particularly appropriate heat-sealing strength, to the heat-sealed paper. For example, the core part is PP and the sheath part is PP or polyethylene (hereinafter also referred to as PE). Composite fiber) is preferably used.

  In the PP fiber having the core-sheath structure, the melting point of the core part is preferably about 155 to 170 ° C., the melting point of the sheath part is preferably about 130 to 150 ° C., and the fineness is about 1.4 to 3.0 dtex. The fiber length is preferably about 4 to 6 mm.

  The PET fiber having the core-sheath structure can improve the fixing property of the fiber in the heat-seal paper, give the heat-seal paper a uniform texture, and can be appropriately clogged. It is also possible for the paper to shrink easily. As the PET fiber having a core-sheath structure, for example, a composite fiber having a core part of PET and a sheath part of PE is preferably used.

  In the PET fiber having a core-sheath structure, the melting point of the core part is preferably about 240 to 280 ° C., the melting point of the sheath part is preferably about 90 to 135 ° C., and the fineness is about 0.5 to 1.7 dtex. The fiber length is preferably about 4 to 6 mm.

  The PET fiber not having the core-sheath structure can impart a uniform texture to the heat-sealed paper and can be appropriately clogged, and can also improve the shrinkability of the heat-sealed paper. .

  The PET fiber having no core-sheath structure preferably has a melting point of about 240 to 280 ° C, a fineness of about 0.1 to 1.2 dtex, and a fiber length of about 4 to 6 mm.

  The amount of each fiber in the synthetic fiber mixture is appropriately adjusted in consideration of appropriate extractability to heat-sealed paper and imparting excellent mechanical strength and heat-sealing properties. PP fiber having a core / sheath structure is 10 to 20 parts by mass, further 13 to 18 parts by mass, PET fiber having a core / sheath structure is 30 to 50 parts by mass, further 35 to 45 parts by mass, and It is preferable that 10-30 mass parts, and also 13-18 mass parts of PET fiber which does not have a core-sheath structure are contained.

  When the amount of the PP fiber having a core-sheath structure is less than 10 parts by mass, the heat seal paper is not sufficiently provided with heat sealability, particularly appropriate heat seal strength, and the rigidity of the base material is lowered and mechanical strength is reduced. May decrease. Moreover, when the quantity of PP fiber which has a core-sheath structure exceeds 20 mass parts, there exists a possibility that the powder removal performance at the time of using for a filter may fall.

  If the amount of the PET fiber having the core-sheath structure is less than 30 parts by mass, the fixing property of the fiber in the heat-sealed paper may not be sufficiently improved, and a uniform texture is not imparted to the heat-sealed paper, resulting in clogging. There is a risk of becoming insufficient. Moreover, when the quantity of PET fiber which has a core-sheath structure exceeds 50 mass parts, there exists a possibility that the powder removal performance at the time of using for a filter may fall.

  If the amount of PET fiber not having a core-sheath structure is less than 10 parts by mass, the heat-sealed paper may not be provided with a uniform texture, and clogging may be insufficient. There is a risk that it will not improve sufficiently. Moreover, when the quantity of PET fiber which does not have a core-sheath structure exceeds 30 mass parts, there exists a possibility that the provision effect of the heat seal property by PP fiber which has a core-sheath structure may be inhibited.

  The synthetic fiber mixture may contain, for example, kraft pulp fibers in addition to the synthetic fibers. As the kraft pulp fiber, for example, kraft pulp such as the chemical pulp can be used. The kraft pulp contained in the synthetic fiber mixture may be the same type as the kraft pulp such as the chemical pulp, or may be a different type, but using NBKP is suitable for heat-seal paper. And the effect of imparting heat seal strength is preferable.

  In the synthetic fiber mixture, when blending pre-kraft pulp fibers in addition to the synthetic fibers, the amount is adjusted to 20 to 50 parts by mass, further 25 to 35 parts by mass with respect to 100 parts by mass of the mixture. It is preferable from the viewpoint of improving the appropriate extractability and powder removal performance of heat-sealed paper and reducing the pressure-sensitive adhesive derived from synthetic fibers during the heat-sealing process.

  In the method for producing heat-sealed paper of the present invention, first, a raw pulp slurry is prepared from a fiber mixture containing a mixture of kraft pulp fibers and synthetic fibers.

  The raw material pulp slurry appropriately selects kraft pulp as kraft pulp fiber, and PP fiber having a core-sheath structure as a mixture of synthetic fibers, PET fiber having a core-sheath structure and PET fiber not having a core-sheath structure, and necessary It can be prepared by appropriately selecting kraft pulp or the like and blending each component.

  When preparing the raw material pulp slurry, for example, an additive chemical such as a viscosity modifier, a dispersant, a dry paper strength enhancer, a wet paper strength enhancer, an antifoaming agent, a release agent, and a fixing agent may be appropriately blended. it can. It is preferable to appropriately change the type of these additive chemicals according to the raw materials of the mixture of kraft pulp fiber and synthetic fiber.

  Next, the raw pulp slurry is wet-made with a paper machine to produce a heat-sealed base paper.

  In the production method of the present invention, one of the characteristics is that the raw pulp slurry is subjected to wet papermaking instead of dry papermaking. When conventional heat-sealed paper is used for coffee filters such as pod filters, for example, coffee powder particles often fall off, and preventing such powder-off is a problem when using heat-sealed paper. It was. The powder omission of the fine powder particles is related to the elongation of the heat-sealed paper, and the heat-sealed paper obtained by dry papermaking the raw pulp slurry becomes too large to cause powder omission during use. By wet papermaking the raw pulp slurry, it becomes possible to appropriately adjust the elongation of the heat-sealed paper and prevent powder falling off during use. In addition, when the heat-seal paper is too small in elongation, the mechanical strength tends to decrease, but by adjusting the elongation appropriately in this way, it prevents powder falling off during use and improves the mechanical strength. You can also.

  When wet papermaking is performed on the raw pulp slurry, a paper machine equipped with a circular net and an inclined short net is used for the wire part. In this way, by wet papermaking with a paper machine equipped with a circular net and a slanted short net, it is possible to give a uniform texture to the heat-sealed paper and to be appropriately clogged, By adjusting the ratio (Y / T) of the tensile strength (Y) in the transverse direction and the tensile strength (T) in the longitudinal direction of the seal paper, it is possible to impart an appropriate extractability to the heat seal paper.

  As described above, the raw pulp slurry is prepared from a fiber mixture containing a mixture of kraft pulp fibers and synthetic fibers, and the raw pulp slurry prepared from kraft pulp fibers is supplied to the wire part circular net to perform wet papermaking. One paper layer (hereinafter also referred to as paper layer A) and raw pulp slurry prepared from a mixture of synthetic fibers is supplied to the inclined short net of the wire part for wet papermaking, and another paper layer (Hereinafter also referred to as paper layer B).

  When supplying raw pulp slurry prepared from kraft pulp fiber to a circular net and making paper by adjusting the paper making speed and paper making time as appropriate, it gives a uniform texture to the heat-sealed paper so that it will be clogged appropriately In view of the above, it is preferable to set the wire mesh of the circular net to 140 mesh or less, and further to 70 to 100 mesh. When the wire mesh of the circular mesh exceeds 140 mesh, the dewatering efficiency deteriorates. Therefore, when the raw pulp slurry is made into a sheet and made into a sheet, the uniformity of the sheet is lowered, and the desired uniform heat seal is formed. It becomes difficult to obtain paper. Moreover, when the wire mesh of the circular net is less than 70 mesh, when making the raw pulp slurry, fine pulp fibers are dropped from the paper machine wire, and when the sheet is made into a sheet, appropriate clogging is not given, It becomes difficult to obtain sufficient powder-off performance required for heat-sealed paper.

  When the raw pulp slurry prepared from the synthetic fiber mixture is supplied to the inclined short mesh for paper making, the paper making speed and the paper making time are adjusted appropriately, and the inclination angle of the inclined short mesh is adjusted to The ratio (Y / T) of the tensile strength (Y) in the transverse direction and the tensile strength (T) in the longitudinal direction of the sticker paper can be set within a desired range. The value of Y / T is preferably set to 0.30 or more from the viewpoint of imparting appropriate extractability to the heat-sealed paper, as will be described later. In order to obtain the above, it is preferable to adjust the inclined short net to an inclination angle of 10.0 to 15.0 degrees, more preferably 11.0 to 14.0 degrees.

  Next, for example, the paper layer A and the paper layer B obtained as described above are combined and dehydrated by appropriately setting conditions in a press part of a paper machine to produce a heat-seal base paper. Next, the heat-seal base paper is sent to a dryer part and dried by appropriately adjusting the drying temperature and drying time.

  Next, heat treatment is performed on the dried heat-sealed base paper with a heat calendar. Here, it is one of the characteristics of the manufacturing method of the present invention that the heat treatment is performed not on both sides of the heat-sealed base paper but on one side. When heat treatment is not performed on the heat-seal base paper with a heat calender, the PP fiber having the core-sheath structure does not sufficiently exhibit the effect of imparting heat-seal properties, particularly moderate heat-seal strength, to the heat-seal paper. . In addition, when heat treatment is performed on both surfaces of the heat-seal base paper with a heat calendar, the heat-seal paper is densified, and the extractability required for filter use cannot be secured. That is, by performing heat treatment on one side of the heat-seal base paper with a heat calendar, the synthetic fibers are sufficiently fixed to each other, the heat-seal paper is appropriately bulky (low density), and the extractability is improved. It becomes clogged and powder fall during use is sufficiently reduced.

  It is preferable that the heating temperature at the time of heat-processing with a heat calendar is 150-200 degreeC, Furthermore, it is preferable that it is 155-190 degreeC. When the heating temperature is less than 150 ° C., the heat-fusibility between the synthetic fibers is insufficient, and the mechanical strength may be lowered or the fibers may fall off the sheet. On the other hand, when the heating temperature exceeds 200 ° C., the synthetic fiber is completely melted and the fiber shape cannot be maintained, and the mechanical strength and other performance may be deteriorated.

  In addition, it is preferable to perform the heat processing by the said heat | fever calendar substantially, without pressurizing a heat | fever calendar roll. By applying the heat treatment only by bringing the heat roll into contact with the heat seal base paper without applying pressure to the heat calender roll, the thickness of the heat seal paper obtained does not become too small. Appropriate shrinkage is imparted. This makes it possible to increase both the conflicting qualities of extractability and mechanical strength.

The heat-sealed paper of the present invention thus obtained has a ratio (CD ₁ / MD ₁ ) between the transverse tensile elongation (CD ₁ ) and longitudinal tensile elongation (MD ₁ ) obtained according to JIS P 8116: 2000. ) Is 1.10 or more, and the ratio (CD ₂ ) of the transverse wet tensile elongation (CD ₂ ) and longitudinal wet tensile elongation (MD ₂ ) obtained in accordance with JIS P 8135: 1998 / MD ₂ ) is 1.00 or more. When CD ₁ / MD ₁ is less than 1.10 and / or when CD ₂ / MD ₂ is less than 1.00, powder falling off during use is not sufficiently reduced, and extractability is not good. It is enough. CD ₁ / MD ₁ is preferably 1.10 to 2.00, more preferably 1.20 to 1.45, and CD ₂ / MD ₂ is 1.00 to 1.90, more preferably 1.10. It is preferably ˜1.40. Further, CD ₁ is preferably about 2.5 to 4.5%, MD ₁ is preferably about 2.0 to 3.5%, CD ₂ is about 6.0 to 8.5%, MD ₂ is about 3 It is preferably about 5 to 7.0%.

  The heat seal paper of the present invention has an air resistance obtained in accordance with JIS P 8117: 2009 (low pressure method) of 1.0 to 2.5 seconds, and further 1.3 to 2.0 seconds. It is preferable. If the air resistance is less than 1.0 seconds, the extractability may be insufficient. On the other hand, when the air resistance exceeds 2.5 seconds, the powder falling performance is lowered, and there is a possibility that an appropriate extractability cannot be obtained. The air resistance is a value measured by laminating 30 sheets of heat-sealed paper as described later.

  The ratio (Y / T) of the tensile strength (Y) in the transverse direction and the tensile strength (T) in the longitudinal direction obtained in accordance with JIS P 8113: 2006 of the heat seal paper is said to obtain an appropriate extractability. From the viewpoint, it is preferably 0.30 or more, more preferably 0.40 to 0.50. Y is preferably 0.40 to 1.00 kN / m, and T is preferably 1.00 to 2.10 kN / m.

The heat seal strength of the heat seal paper obtained in accordance with JIS Z 0238: 1998 is to maintain the strength of the sealed portion when processed into a pod filter and to maintain the shape processed when used as a pod filter. From 70 to 200 N / m, more preferably from 80 to 150 N / m. The heat seal strength is a value measured on a sample obtained by heat sealing a heat seal paper under the conditions of 160 ° C. and a pressure of 0.5 kg / cm ² as described later.

The basis weight obtained in accordance with JIS P 8124: 2011 of the heat-sealed paper is preferably about ²⁰ to 35 g / m ² , and the thickness obtained in accordance with JIS P 8118: 2014 is 70 to It is preferable that it is about 110 micrometers, and it is preferable that the density obtained similarly based on JISP8118: 2014 is about 0.2-0.4 g / cm < ³ >.

  As described above, the heat-sealed paper of the present invention is obtained by using a fiber mixture containing kraft pulp fibers and a mixture of three specific synthetic fibers as a raw material, and subjecting one side of a base paper obtained by wet papermaking to heat treatment. The ratio between the tensile elongation in the transverse direction and the tensile elongation in the longitudinal direction is within a specific range, and the ratio between the wet tensile elongation in the transverse direction and the wet tensile elongation in the longitudinal direction is also within the specific range. Therefore, the heat-sealed paper of the present invention is reduced in powder fine particles such as coffee during use, has an appropriate extractability, and is excellent in mechanical strength and heat-sealability.

  Next, the heat seal paper and the method for producing the same according to the present invention will be described in more detail based on the following examples, but the present invention is not limited to these examples. The number of parts in the blend is the number of solids.

  The components used in each of the preparation examples, examples and comparative examples are as follows.

(1) Kraft pulp fiber and NBKP
Softwood bleached kraft pulp Freeness (CSF) in accordance with JIS P 811-2: 2012: Approximately 500 ml

(2) PP fiber having a mixture of synthetic fibers / core-sheath structure (core-sheath PP)
Core: PP (melting point 160 ° C.) Sheath: PE (melting point 140 ° C.)
Fineness: 2.2 dtex, fiber length: 5 mm
-PET fiber having a core-sheath structure (core-sheath PET)
Core: PET (melting point 260 ° C.) Sheath: PE (melting point 110 ° C.)
Fineness: 1.1 dtex, fiber length: 5 mm
・ PET fibers that do not have a core-sheath structure (usually PET)
Melting point: 260 ° C., fineness: 0.6 dtex, fiber length: 5 mm
・ NBKP
Softwood bleached kraft pulp Freeness (CSF) in accordance with JIS P 811-2: 2012: Approximately 500 ml

Preparation Example 1 (Preparation of raw pulp slurry)
A thickener, a dispersant and an antifoaming agent are added to the water in which NBKP is dispersed, and a dry paper strength enhancer (product name: Serogen SG, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) is added to 100 parts by mass of NBKP. 0.2 parts by mass and 2.0 parts by mass of a wet paper strength enhancer (product name: WS-4024, manufactured by Seiko PMC Co., Ltd.) were blended to prepare NBKP raw material pulp slurry A.

  Moreover, 15.0 mass% of core-sheath PP, 40.0 mass% of core-sheath PET, 15.0 mass% of normal PET, and 30.0 mass% of NBKP were mix | blended, and the mixture of the synthetic fiber was obtained. A thickener, a dispersant and an antifoaming agent are added to water in which the synthetic fiber mixture is dispersed, and a dry paper strength enhancer (product name: Serogen SG, Daiichi Kogyo Seiyaku Co., Ltd.) is added to 100 parts by mass of NBKP. Co., Ltd.) 0.2 parts by mass, wet paper strength enhancer (product name: WS-4024, manufactured by Seiko PMC Co., Ltd.) 2.0 parts by mass, and raw material pulp slurry B1 of a synthetic fiber mixture Was prepared.

Preparation Example 2 (Preparation of raw pulp slurry)
Raw material pulp slurry A was prepared in the same manner as in Preparation Example 1. Further, as a mixture of synthetic fibers, Preparation Example 1 except that 11.0% by mass of core-sheath PP, 44.0% by mass of core-sheath PET, 15.0% by mass of normal PET, and 30.0% by mass of NBKP were blended. Similarly, raw material pulp slurry B2 was prepared.

Preparation Example 3 (Preparation of raw pulp slurry)
Raw material pulp slurry A was prepared in the same manner as in Preparation Example 1. Further, as a mixture of synthetic fibers, Preparation Example 1 except that 19.0% by mass of core-sheath PP, 36.0% by mass of core-sheath PET, 15.0% by mass of normal PET, and 30.0% by mass of NBKP were blended. Similarly, raw material pulp slurry B3 was prepared.

Preparation Example 4 (Preparation of raw pulp slurry)
Raw material pulp slurry A was prepared in the same manner as in Preparation Example 1. Further, as a mixture of synthetic fibers, Preparation Example 1 except that 11.0% by mass of core-sheath PP, 30.0% by mass of core-sheath PET, 11.0% by mass of normal PET, and 48.0% by mass of NBKP were blended. Similarly, raw material pulp slurry B4 was prepared.

Comparative Preparation Example 1 (Preparation of raw pulp slurry)
Raw material pulp slurry A was prepared in the same manner as in Preparation Example 1. Further, as a mixture of synthetic fibers, the same procedure as in Preparation Example 1 was performed except that the core-sheath PP was not used, and the core-sheath PET 55.0% by mass, the normal PET 15.0% by mass, and the NBKP 30.0% by mass were blended. A raw material pulp slurry B′1 was prepared.

Comparative Preparation Example 2 (Preparation of raw pulp slurry)
Raw material pulp slurry A was prepared in the same manner as in Preparation Example 1. Further, as a synthetic fiber mixture, the same procedure as in Preparation Example 1 was conducted except that the core-sheath PET was not used, and the core-sheath PP was 55.0% by mass, the normal PET was 15.0% by mass, and the NBKP was 30.0% by mass. The raw material pulp slurry B′2 was prepared.

Example 1 (Production of heat-sealed paper)
Raw material pulp slurry A and raw pulp obtained in Preparation Example 1 using a paper machine equipped with a circular net and a slanted short net in the wire part, so that the basis weight of the heat seal paper is about 22 g / m ^2. Slurry B1 was wet-made.

  Raw material pulp slurry A was supplied to a circular net (wire mesh: 80 mesh), and paper was made under conditions of paper making speed of 80 m / min. Further, the raw pulp slurry B1 was supplied to the inclined short mesh, and the paper layer B was obtained by paper making under the conditions of the inclination angle of 13.8 degrees and the paper making speed of 80 m / min. The obtained paper layer A and paper layer B were superposed and dehydrated by a press part of a paper machine to produce a heat-seal base paper.

  The obtained heat-sealed base paper was sent to a dryer part of a paper machine and dried. The dried heat-sealed base paper is sent to the calender part of the paper machine, and heat treatment is performed on one side of the heat-sealed base paper with a heat calender without applying pressure at a heating temperature of 155 ° C. and a processing speed of 100 m / min. Manufactured.

Examples 2 to 6 (Production of heat-sealed paper)
A heat-sealed paper was produced in the same manner as in Example 1 except that the type of raw material pulp slurry or the conditions of the heat treatment by the heat calendar were changed as shown in Table 1.

Example 7 (Production of heat-sealed paper)
The raw pulp slurry A and raw pulp slurry B1 obtained in Preparation Example 1 are wet-made so that the basis weight of the heat-sealed paper is about 30 g / m ^2, and the heat treatment conditions by the heat calender are set to the heating temperature of 185 ° C. A heat-sealed paper was produced in the same manner as in Example 1 except that the processing speed was changed to 100 m / min.

Examples 8-12 (Production of heat-sealed paper)
A heat-sealed paper was produced in the same manner as in Example 7 except that the type of raw material pulp slurry or the conditions of the heat treatment by the heat calendar were changed as shown in Table 1.

Comparative Examples 1 and 2 (Manufacture of heat seal paper)
A heat-sealed paper was produced in the same manner as in Example 7 except that the type of raw material pulp slurry and / or the heat treatment conditions by the heat calendar were changed as shown in Table 1.

Comparative Example 3 (Production of heat seal paper)
In addition to supplying the raw pulp slurry A and raw pulp slurry B1 to the circular net without using the slanted short net in the wire part of the paper machine, and changing the processing speed of the heat treatment by the thermal calendar to 50 m / min, A heat-sealed paper was produced in the same manner as in Example 1.

Comparative Example 4 (Manufacture of heat seal paper)
A heat-sealed paper was produced in the same manner as in Example 7 except that the heat treatment by the heat calendar was not performed.

Test Example The physical properties and characteristics of the obtained heat seal paper were examined according to the following method. The results are shown in Tables 1 and 2.

(1) Lateral tensile elongation (CD ₁ ) and longitudinal tensile elongation (MD ₁ )
It calculated | required based on JISP8116: 2000. From these values, the ratio of CD ₁ to MD ₁ (CD ₁ / MD ₁ ) was calculated.

(2) Wet tensile elongation in the transverse direction (CD ₂ ) and wet tensile elongation in the longitudinal direction (MD ₂ )
It calculated | required based on JISP8135: 1998. Also from these values was calculated the ratio of CD ₂ and _{MD 2 (CD 2 / MD 2} ).

(3) Air permeability resistance In accordance with JIS P 8117: 2009 “Paper and paperboard—Air permeability test method—Gurley test machine method” (low pressure method), 100 ml of air passes through a stack of 30 heat-sealed papers. The time (seconds) to be measured was measured.

(4) Tensile strength (Y) in the transverse direction and tensile strength (T) in the longitudinal direction
It calculated | required based on JISP8113: 2006. From these values, the ratio of Y to T (Y / T) was calculated.

(5) Basis weight It calculated | required based on JISP8124: 2011.

(6) Thickness and density It calculated | required based on JISP8118: 2014.

(7) Heat seal strength Based on JIS Z 0238: 1998, it measured about the sample obtained by heat-sealing a heat seal paper on the conditions of 160 degreeC and the pressure of 0.5 kg / cm < ² >.

(8) Extractability When the heat seal paper is applied to the opening of the plastic bottle and 100 ml of water is poured into the plastic bottle from the heat seal paper, the time required for the entire amount of water to flow out of the heat seal paper. Measured with a commercially available stopwatch.

  In addition, it was judged that the heat-sealed paper whose measurement result was 8.0 seconds or less could not be used as a coffee filter because the liquid passed through too early to extract a coffee liquid having an appropriate concentration. Heat seal paper with a measurement result of 22.0 seconds or more was able to extract a coffee liquid with a suitable concentration, but it was too slow to pass and the extractability was slow and operability was poor. It was judged that it was not applicable to the coffee maker equipment.

(9) Powder drop 10 g of commercially available coffee powder was wrapped in heat-sealed paper, and heat-sealed and packaged. Next, the obtained packaging is placed on a cup, 100 ml of hot water is poured into it, and the coffee liquid obtained by extracting the coffee is allowed to stand for 30 minutes, and then the sediment accumulated on the bottom of the cup is visually confirmed. And evaluated based on the following evaluation criteria.
(Evaluation criteria)
A: No coffee powder was confirmed at the bottom of the cup.
○: Coffee powder was confirmed slightly at the bottom of the cup, but there was no problem in use.
X: The coffee powder is generally confirmed at the bottom of the cup and cannot be used.

  The heat-sealed paper of Examples 1 to 12 is a mixture of three types of synthetic fibers: kraft pulp fibers, PP fibers having a core-sheath structure, PET fibers having a core-sheath structure, and PET fibers not having a core-sheath structure. Is obtained by subjecting one side of a base paper wet-formed by a paper machine having a circular net and a slanted short net to a heat treatment with a thermal calendar.

Therefore, heat sealing paper of Example 1-12 _is a CD 1 / MD ₁ 1.10 or more, and is a _CD 2 / MD ₂ is 1.00 or more, dusting is sufficiently reduced, moderate extraction And has excellent mechanical strength and heat sealability.

  On the other hand, since the heat-sealed paper of Comparative Example 1 was obtained without using PP fibers having a core-sheath structure, although powder falling was reduced, the extractability was inferior and the operability was low. It is bad and cannot be used as a coffee filter.

  Since the heat-sealed paper of Comparative Example 2 was obtained without using PET fibers having a core-sheath structure, the extractability was inferior, and it was impossible to extract a coffee liquid having a suitable concentration. The coffee powder is confirmed in the whole coffee liquid and cannot be used as a coffee filter.

  The heat-sealed paper of Comparative Example 3 was obtained by wet papermaking using only a circular net without using a slanted short net at the wire part of a paper machine. In addition, the liquid cannot be extracted, and coffee powder is confirmed throughout the extracted coffee liquid, and cannot be used as a coffee filter.

  Since the heat-sealed paper of Comparative Example 4 was obtained without subjecting the heat-sealed base paper to heat treatment with a heat calender, the extractability was inferior, and a coffee liquid with a suitable concentration could not be extracted. Coffee powder is confirmed in the entire coffee liquid after extraction and cannot be used as a coffee filter.

  The heat seal paper of the present invention can be suitably used for a coffee filter such as a pod filter.

Claims (6)

A raw pulp slurry prepared from a fiber mixture containing a mixture of kraft pulp fiber and synthetic fiber is wet-papered,
The synthetic fiber mixture includes a polypropylene fiber having a core-sheath structure, a polyethylene terephthalate fiber having a core-sheath structure, and a polyethylene terephthalate fiber having no core-sheath structure,
The ratio (CD ₁ / MD ₁ ) between the tensile elongation (CD ₁ ) in the transverse direction and the tensile elongation (MD ₁ ) in the longitudinal direction obtained according to JIS P 8116 is 1.10 or more, and JIS P The heat seal paper having a ratio (CD ₂ / MD ₂ ) of the wet tensile elongation in the transverse direction (CD ₂ ) and the wet tensile elongation in the longitudinal direction (MD ₂ ) obtained in accordance with 8135 of 1.00 or more. .   10 to 20 parts by mass of polypropylene fiber having a core-sheath structure, 30 to 50 parts by mass of polyethylene terephthalate fiber having a core-sheath structure, and polyethylene terephthalate having no core-sheath structure with respect to 100 parts by mass of the synthetic fiber mixture The heat-sealed paper according to claim 1, wherein 10 to 30 parts by mass of fibers are contained.   The heat seal paper according to claim 1 or 2, wherein the air resistance obtained in accordance with JIS P 8117 is 1.0 to 2.5 seconds. It is a manufacturing method of the heat seal paper of Claim 1, Comprising:
Preparing a raw pulp slurry from the fiber mixture;
A process of wet-making the raw pulp slurry with a paper machine equipped with a circular net and a slanted short net to produce a heat-sealed base paper,
A method for producing heat-sealed paper, comprising a step of performing heat treatment on one side of the heat-sealed base paper with a heat calendar.   The manufacturing method of Claim 4 which heat-processes with a heat calendar at 150-200 degreeC. The wire mesh of the circular mesh is made 140 mesh or less, the raw pulp slurry prepared from kraft pulp fiber is wet-papered to form one paper layer, and the inclined short mesh is inclined at 10.0 to 15.0 degrees. The production method according to claim 4 or 5, wherein the raw pulp slurry prepared from the synthetic fiber mixture is wet-papered to form another paper layer.