JP2613274B2 - Synthetic paper - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to synthetic paper having heat sealability, which is used for disposable bags such as soybeans such as toibagu or bonito, insect repellents, desiccants and the like. .

[Conventional technology]

Conventionally, as a paper having heat sealing properties and used for toy bags and the like, as the first layer, ordinary wood pulp, pulp such as hemp pulp, and a fiber having a relatively low melting point polymer and having heat sealing properties, For example, a paper made by mixing polyethylene fibers or polypropylene fibers, and as the second layer, a paper made of the above various pulp and fibers having no heat sealing property or a paper obtained by further heat-treating the paper, Japanese Patent Application Laid-Open No. 59-228100, that is, a paper comprising at least a part of a fiber having a low melting point component, a first layer composed of polyester fibers, and polyester fibers (hereinafter referred to as ester fibers), and having a heat-sealing property. Synthetic paper obtained by laminating and integrating a second layer having no
Both the first layer and the second layer include synthetic paper containing 30% or more of low-oriented polyester fiber (hereinafter referred to as PET binder).

[Problems to be solved by the invention]

Of these, synthetic paper has a wood pulp or hemp pulp that absorbs aroma components in applications where it is required that the delicate fragrance is not lost when eluted by pouring hot water such as green tea or black tea. And spoil the flavor. In addition, since such synthetic papers contain polyolefin fibers and rayon fibers but do not use appropriate binder fibers, the paper strength after papermaking is extremely low, especially for drying agents and insect repellents. When used for packaging, there is a concern that the contents will be exposed due to the breakage of the bag during handling, and that there is a possibility of contaminating the surrounding ones, which is unusable. If the obtained paper is heat-treated to melt and bond the first layer of polyolefin fibers in order to improve the paper strength, the cost must be increased.

Since synthetic paper has ester fibers as a main component,
It does not impair the flavor when used in green tea or black tea, etc. like synthetic paper, but it does not use an appropriate binder like synthetic paper and has low paper strength after paper making, and 150 ° C or higher. The high-temperature shrinkable ester fiber is used as the main fiber, so the paper shrinks due to the heat seal when packaging the contents such as green tea and desiccant, and the molded bag is deformed, significantly increasing the commercial value. There are disadvantages that are impaired.

The present invention solves the above-mentioned drawbacks of the synthetic paper according to the conventional technology, and when used in a tea bag such as green tea or black tea, does not lose its flavor by adsorbing its components, and is sufficient for use only by papermaking. It has the paper strength to withstand, and hardly shrinks due to heat sealing during bag making, so there is no deformation of the bag,
Another object of the present invention is to provide a synthetic paper having excellent heat sealability.

[Means for solving the problem]

The present invention is a two-layered paper, wherein the first layer is
5% by weight of compound fiber with shrinkage of less than 10% at 200 ℃
As described above, the second layer contains 10 to 95% by weight of a fiber having a low melting point component having a melting point of at least 105 ° C to 130 ° C on at least a part of its surface.
5% by weight of compound fiber with shrinkage of less than 10% at 200 ℃
As described above, the melting point is 240 ° C to 270 ° C, the birefringence (hereinafter referred to as Δn) is 0.020 or less, and the intrinsic viscosity (hereinafter referred to as [η]).
Is a polyethylene terephthalate fibrous binder (hereinafter referred to as low [η] PET binder) having a
It is a synthetic paper characterized by containing about 95% by weight.

Since the synthetic paper of the present invention does not substantially contain a cellulosic pulp substance such as wood pulp or hemp pulp, when used as a wrapping paper for green tea, black tea or the like, its components are adsorbed to impair the flavor. Since the first layer and the second layer contain low-shrinkage fibers as main fibers, even when the paper is rapidly heated during heat sealing, the paper hardly shrinks. Since the bag that has been packaged does not deform and the second layer contains a low [η] PET binder, it exhibits sufficient binder performance only in the drying step after papermaking, and can be used not only when dry but also when wet. There is no need to heat-treat the paper again to express high paper strength, so it is low cost,
Since the first layer contains a fiber having a low melting point polymer having a melting point of at least 105 ° C. to 130 ° C. on at least a part of the surface, the first layers are folded in two so as to be in contact with each other and heat-sealed. When the bag is firmly adhered, and the bag is handled after the bag is made, for example, the heat seal portion is not peeled off even when boiled in water as a bag or by any external force, and the temperature of the sealer at the time of heat seal is, for example, 130 ° C. In addition to exhibiting sufficient heat sealing strength even at a low temperature of about ℃, the heat sealer temperature fluctuates. For example, even at a high temperature of about 170 ℃, a portion composed of a high melting polymer is a low melting polymer in the second layer. Since it does not flow to the side, it does not fuse to the surface of the heat sealer to cause trouble during heat sealing.

As described above, the synthetic paper of the present invention having excellent performance can be obtained only by combining the above components.

The low-shrinkage fiber used in the present invention is a compound fiber in which the fiber is put on a hot plate at 200 ° C. for 1 minute and the shrinkage of which is 10% or less, and the first and second layers of the synthetic paper of the present invention. It is used as a main fiber in both layers and exhibits the effect of suppressing shrinkage at a heat sealing temperature of 150 ° C or higher. The mixing amount is 5% by weight or more for both the first layer and the second layer, preferably 30 to 60%.
If the blending amount is less than 5% by weight, shrinkage occurs during heat sealing, and deformation of the bag occurs. Low-shrink fibers include vinylon fiber, rayon fiber, acrylic fiber,
A polyamide fiber or an ester-based fiber which is appropriately heat-treated to have a shrinkage ratio of 10% or less under the above conditions is used. These fibers may be used as a mixture of two or more kinds. The fineness of this low shrinkage fiber is 0.1 to 4.0 denier, and the fiber length is 1 to
25 mm is preferred.

The low [η] PET binder is used in the second layer of the present invention and acts as a binder in a drying step during papermaking.
Such a binder has a melting point of 240 ° C. to 270 ° C. and (η) of 0.2.
Consisting of 50 to 0.58, preferably 0.52 to 0.56 polyethylene terephthalate, Δn is not more than 0.020, preferably 0.015
It is as follows. Preferably, the fineness is 0.1 to 4.0 denier and the fiber length is 1 to 25 mm. If the melting point is less than 240 ° C., it sticks to the sealer during heat sealing, and if it exceeds 270 ° C., the paper strength decreases. If [η] is less than 0.50, the fiber-forming property is poor, and if it exceeds 0.58, the paper strength of the synthetic paper obtained due to insufficient binder performance is reduced.

The low-melting polymer of the fiber having at least a part of the low-melting polymer used in the present invention is a polymer such as polyolefin, ie, polyethylene, polypropylene, or copolyester, and has a melting point of 105 ° C. 130 ° C, preferably 110 ° C to 120 ° C.

When the melting point is lower than 105 ° C., for example, when used in boiling water such as toy bag, the heat-sealed portion peels off,
When the temperature exceeds 130 ° C, the heat sealing temperature becomes 130 ° C, for example.
At low temperatures, sufficient sheet sealing properties cannot be obtained.

As such a fiber, a core-sheath fiber having the low-melting polymer as a sheath component, a sea-island composite fiber having the low-melting polymer as a sea component, or the like is used. In short, it is not particularly limited as long as it is a multicomponent fiber molded so that the low melting point polymer occupies a part of the surface.

The proportion of the low melting polymer in such fibers is preferably 30 to 70% by weight, and the fineness and fiber length are preferably 1 to 10 denier and 1 to 25 mm, respectively.

In addition to the above-mentioned fibers and binders, each of the first and second layers may be mixed with ordinary polyester fibers for papermaking, nylon fibers, polyolefin fibers, wood pulp, hemp pulp, and the like. However, natural pulp, such as wood pulp, does not exceed 20% by weight in order to impair the flavor when used in toibagu and to reduce the paper strength when wet. Further, these fibers and pulp must be those which do not significantly impair the features of the synthetic paper of the present invention.

The synthetic paper of the present invention is a laminated paper mainly composed of low-shrinkage fibers, and preferably has a basis weight of 8 to 30 g / m ² and a basis weight ratio of the first layer to the second layer of 3: 7 to 7: 3 is preferred.

The synthetic paper of the present invention can be easily produced on a normal paper machine capable of being laminated. The paper net used may be a circular net or a short net, and the dryer is preferably a Yankee type, but may be a multi-cylinder type or a through type.

The heat shrinkage of the fiber in the present invention is determined by placing the main fiber on a hot plate at 200 ° C. for 1 minute, then cooling in air for 15 minutes, measuring the fiber length before and after the hot plate treatment, and using the following formula. This is calculated.

Shrinkage ratio during heat sealing is narrowed between two metal plates with width of 100mm, length of 15mm and surface temperature of 170 ° C by folding the first layer of 160mm wide strip-shaped synthetic paper into contact with each other. , 1
Crimping was performed at a pressure of 0 kg / cm ² for 0.5 seconds, and the length before and after the compression was measured and calculated by the following equation.

The method for measuring [η] and Δn in the present invention is as follows.

[Η]: Polyethylene terephthalate fiber was dissolved in a mixed solvent of equal amounts of phenol and tetrachloroethane and measured at 30 ° C.

Δn: Using a polarizing microscope manufactured by Nippon Kogaku Co., Ltd. and using a sodium light source lamp, the letter value was calculated from the Berek compensator method and calculated.

〔Example〕

Hereinafter, the present invention will be described more specifically with reference to examples.
The percentages shown in Examples and Comparative Examples are values based on weight.

Example 1 The first layer is a low-shrink fiber having a heat shrinkage of 3.2% and a fineness of 1.5 denier, a rayon fiber of 5 mm in fiber length of 15%, a fineness and a fiber length of 0.5 denier and 5 mm, respectively, and a heat shrinkage of 18.5%. 15% polyester fiber for papermaking, melting point 110 ° C
The copolyester as a sheath component, polyethylene terephthalate as a core component, the weight ratio of the sheath component and the core component is 1:
The 2nd layer is composed of 25% of rayon fiber and papermaking polyester fiber used for the 1st layer, the denier is 1.0 denier and the fiber length is 1.0 denier. 5 mm, using a stock consisting of 50% of low [η] PET binder fibers with [η] of 0.55 and Δn of 0.014,
The first layer and the second layer are formed by using a paper machine capable of assembling an ordinary short net and a short net and a Yankee dryer having a surface temperature of 120 ° C.
A synthetic paper having a basis weight ratio of 1: 1 and a basis weight of 20.5 g / m ^{2 was} prepared.

Example 2 Low shrinkage fiber had a heat shrinkage of 5.0% and a formalization degree of 28.0
%, A synthetic paper was made in the same manner as in Example 1 except that it was a vinylon fiber having a fineness of 0.5 denier and a fiber length of 3 mm.

Comparative Example 1 The first layer is a papermaking polyester fiber used in Example 1.
As in Example 1, using a paper machine consisting of 30% core and 70% core-sheath fibers, and the second layer comprising 50% of the papermaking polyester fiber used in Example 1 and 50% of low [η] PET binder fiber. , A synthetic paper having a basis weight of 19.5 g / m ² was obtained.

Comparative Example 2 The method of Example 1 was repeated, except that [η] was 0.62, Δn was 0.08, 1.0 denier, 5
Synthetic paper having a basis weight of 19.7 g / m ² was obtained in the same manner as in Example 1 by using an ester binder fiber of mm.

Comparative Example 3 According to the method of Example 1, the first layer was composed of 50% of NBKP having a CSF of 550 ml and 50% of polypropylene fiber having a denier of 2 denier and 5 mm, and the second layer was composed of 80% of the NBKP and 20% of the rayon fiber used in Example 1. paper making synthetic paper having a basis weight of 20.1 g / m ² to become more, further 20
Heat treatment was performed in a heat treatment furnace at 0 ° C. for 20 seconds.

Table 1 shows the physical properties of the synthetic papers of Examples 1 and 2 and Comparative Examples 1 to 3.

In Table 1, the tensile strength was measured using a constant-speed elongation measuring instrument in accordance with JISP-8113. The wet strength was measured after immersing a sample of synthetic paper in water at 20 ° C. for 2 hours. Values are average values of MD and CD.

The heat sealing strength is to fold the first layer of synthetic paper with a width of 15 mm so that the first layers are in contact with each other, then narrow it to the sealer used to measure the shrinkage during heat sealing, heat seal, and peel off the adhesive surface Was measured using the above constant-speed elongation type measuring instrument.

〔The invention's effect〕

As described above, the synthetic paper of the present invention has low paper shrinkage during heat sealing while securing heat strength,
Synthetic paper that has high commercial value and can be produced at low cost.It can be widely used in disposable bags that pack green tea, black tea, barley tea and other soup stock, bonito bush stockings, etc., or desiccants and insect repellents. I can do it.

Claims (1)

(57) [Claims] 1. A two-layer assorted paper, wherein the first layer comprises 200
5% by weight or more of a compound fiber having a shrinkage rate of 10% or less at 10 ° C and 10-95% by weight of a fiber having a low melting point component having a melting point of at least 105 ° C to 130 ° C on at least a part of its surface. Two layers, 20
5% by weight or more of a compound fiber having a shrinkage of 10% or less at 0 ° C, a polyethylene terephthalate fibrous binder having a melting point of 240 ° C to 270 ° C, a birefringence of 0.020 or less, and an intrinsic viscosity of 0.50 to 0.58. Is a synthetic paper containing 10 to 95% by weight.