JPS59228100A - Synthetic paper - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] [Industrial application field] The present invention has self-adhesive ability and is used for tea bags, desiccant bags, liquid filters, etc., and has high strength under standard conditions and high wet strength. Regarding synthetic paper.

[Prior art]

Conventionally, paper with self-adhesive ability is known as a paper in which a first layer that does not have adhesive ability and a second layer that has adhesive ability are laminated together, and various materials can be used as the first and second layers. More paper has been developed. For example, the first layer and
- Ordinary wood pulp.

Pulps and fibers such as Manila hemp pulp, vinylon, rayon, and mixtures thereof are used, and the second layer is made of the various fibers and pulps mentioned above, and fibers with relatively low melting points and softening points, such as polyolefin alone. Currently, it is used in combination with fibers made of composite components.

If wood pulp or Manila hemp pulp is used for the first layer,
Paper waste with a certain degree of strength can be obtained without a binder, but it has the disadvantage of low wet strength. When vinylon or rayon is used in the first layer or mixed with pulp, polyvinyl alcohol is used as a binder, and in some cases, a crosslinking agent such as polyamide epichlorohydrin is used as a paper strength agent. However, in this case as well, the wet strength is low and it may not be able to be used satisfactorily depending on the application.

The second layer contains ordinary fiber pulp, a low melting point,
Fibers with a low softening point (hereinafter referred to as low melting point fibers), for example,
It is used in combination with a polyolefin-based fiber consisting of a single spanning composite component. These low melting point fibers are
When stacked and heat-treated, they adhere to each other, giving the paper self-adhesive properties. However, in this case as well, a binder is required to integrate the fibers or pulp, and a binder to prevent delamination between the first layer and the second layer is also required.

[Purpose of the invention]

The purpose of the present invention is to obtain a synthetic paper that has self-adhesive ability, does not require the use of a binder other than the constituent fibers, and has high strength under standard conditions and high wet strength.

However, although the use of polyester fibers, which are originally highly strong and highly water resistant, in synthetic paper has been carried out in the past, the present invention mainly uses polyester fibers that are not made of polyester fibers, and which have the above-mentioned performance. This was done because synthetic paper with . The reason that such synthetic paper has not yet been developed is that a high-strength binder to bind the polyester fibers, a combination of fibers to integrate the two layers, and a method for forming it have not been discovered. by.

The present invention achieves the above object with a new synthetic paper mainly composed of polyester fibers.

[Structure of the invention]

The present invention provides a first layer of synthetic paper made by laminating and integrating a first layer made of polyester fibers and a second layer made of fibers having at least a portion of a low melting point component and polyester fibers. , the birefringence (Δn) of both the second layers is 06
The synthetic paper is characterized by containing 30% by weight or more of low oriented polyester fibers of 03 or less.

As the polyester of the polyester fiber in the present invention, polyethylene terephthalate is suitable, but some of its acid components and/or diol components are dicarboxylic acids such as isofucric acid, sebacic acid, and 5-sodium sulfoisophthalate, diethylene glycol, Copolymerized polyesters substituted with diols such as 1,4-butanediol and polyethylene glycol may also be used. Matting agents, antistatic agents, flame retardants, etc. may be added to these polyesters.

In the present invention, the fiber having at least a part of the low melting point component is a fiber containing a polymer having a melting point or softening point lower than that of the above-mentioned polyester fiber, and is made of polyolefin, that is, a polymer such as polyethylene, polypropylene, or copolymerized polyester. , or fibers that have these polymers as part of them. In particular, fibers with a core-sheath structure containing polyolefin or copolymerized polyester as a sheath component are preferable. These low melting point fibers are included in the second layer from 10 to
It is preferable that it is contained in an amount of 501% by weight.

The low oriented polyester fiber in the present invention has birefringence (Δ
n) is 0.03 or less, and includes undrawn yarns, semi-drawn yarns, intermediately oriented yarns obtained by high-speed spinning, and the like. Here, the birefringence (Δn) is calculated by using a sodium light source and placing it in the optical path of a polarizing microscope.
) was measured in α-bromnaphthalene by inserting a compensator.

The synthetic paper of the present invention is a synthetic paper in which 2M is laminated and integrated, and the first fvI is a polyester fiber having a weight of 30 or more of the low-oriented polyester fibers as described above, and the second
The layer is composed of the above-mentioned low melting point fibers and polyester fibers having a weight of 30 or more low oriented polyester fibers.

These two layers are made using separate paper machines, then overlapped, then water squeezed and dried.
Laminated paper is made using a method called layered papermaking. The paper machine used here may be any one of circular mesh, short screen, and fourdrinier paper machines. Then, the constituent fibers of the two layers are mixed into the paper making bath of the paper machine for each layer and paper is made. Note that when the laminated synthetic paper is compressed by passing it through hot rolls during or after drying in the layered papermaking, the dry and wet strength and delamination durability of the synthetic paper are improved.

The basis weight of the synthetic paper of the present invention obtained as described above, the weight ratio of the first layer and the second layer, and the weight fraction of the fibers constituting each layer can be appropriately selected depending on the intended end use. However, in general, the weight of the synthetic paper of the present invention is 10 to 100f.
/m2, preferably in the range of 16 to 30 r/m
A range of 2 is particularly preferred. The weight ratio of the first layer to the second layer is preferably in the range of 40:60 to 80:20, particularly preferably in the range of 50:50 to 70:30.

In addition, it is preferable that the weight ratio of relatively highly oriented fibers to low oriented fibers in the first layer of polyester fibers is in the range of 70:30 to 40:60, and preferably in the range of 70:30 to 50:50. Particularly preferred. Further, the second layer preferably contains 30% by weight or more of low-melting point fibers, and the remainder is polyester fibers, the polyester fibers being at least 30% by weight.
It is necessary that what corresponds to 0% by weight is a low-oriented polyester fiber with Δn of 0.03 or less. That is,
Low melting point fiber in the second layer, low oriented polyester fiber,
Furthermore, the weight fractions of highly oriented polyester fibers in K are preferably 30 to 70%, 30 to 70%, and 0 to 40%, respectively.

The synthetic paper of the present invention obtained with the above-mentioned structure by the above-mentioned manufacturing method has sufficient dry and wet strength, delamination durability, and especially the second layer without using a binder other than the constituent fibers. It has a self-adhesive ability due to its thermal adhesive properties, and is therefore tasteless and odorless, and harmful substances will not be separated or extracted in the air, water, or hot water, and the constituent fibers will not swell. Since there is no decrease in air permeability or liquid permeability, it is extremely suitable for use as tea bags, seasoning stock bags, and other food packaging materials.

Of course, the synthetic paper of the present invention can also be used for desiccants, insect repellent bags, filters, etc. other than food packaging, and a certain amount of binder etc. may be used for such uses. It may also be something you have.

〔Example〕

The present invention will be further explained below based on specific examples.

Example 1 Synthetic papers of various compositions were laminated using two circular mesh paper machines (details of compositions are shown in Table 1). Here, the highly oriented polyester fiber has a thread denier of 1.5 de
Polyethylene terephthalate fibers with a cut length of 5 mm and a birefringence of 0.161 were used, and as the low-oriented polyester fibers, polyethylene terephthalate fibers with a single yarn denier of 1.1 DE, a cut length of 5 mm, and a birefringence of 0.023 were used. Low-melting point fibers, i.e., fibers having at least a portion of low-melting point components, include fibers with a core-sheath structure in which the core component is polypropylene, the sheath component is polyethylene, the single yarn denier is 4 de, and the cut length is 5 fins. Using. The paper weight is 25 r/
m2, and the first layer is 1597 m2. The second layer was 101/m2. Moreover, the drying temperature was 120°C.

A 1 and A 2 do not contain 30% by weight or more of low-oriented polyester fibers in both the first layer and the second layer.

A3 is small in both strength and heat seal strength, and
Delamination easily occurred due to rubbing. On the contrary,
A4 and A5 (both synthetic papers of the present invention) containing 30% by weight or more of low-oriented polyester fibers in both the first and second layers had excellent strength, heat seal strength, and delamination durability (No. (Table 1).

Example 2゜Example 1 except that polyethylene terephthalate fibers of various birefringences were used as the low-oriented polyester fibers.
Four types of synthetic paper were stacked and made under the same conditions as A4 paper. Note that the same low-oriented polyester fibers were used for both the first layer and the second layer.

Table 2 shows the physical properties of the synthetic paper obtained.

A9 with birefringence exceeding 0.030 had low strength and heat seal strength, and delamination easily occurred due to matting and rubbing. On the other hand, A with birefringence of 0.030 or less
6. 7. Paper No. 8 (all synthetic papers of the present invention, A8 being the same as A4 of Example 1) had excellent strength, heat seal strength, and delamination durability. However, A6, which has extremely low birefringence, tends to be a little stiff like synthetic paper.

Table 2 (Note) For delamination durability, refer to Table 1 (Note).
The strength, heat seal strength and delamination durability shown in Tables 1 and 2 were measured and evaluated by the following methods.

(1) Strength: Measured using a constant speed extension type tensile tester according to JISP-8113 (sample width: 15 mm).

(2) Strong heat sealing...width 15mm, length 15mm (1
Two samples with a layer (second layer) having a low melting point component are sandwiched between two hot plates of m, and a load of I K17 is applied.
cm2. After bonding at a hot plate temperature of 180°C for 1 hour and 10 seconds, three test pieces with a width of 20 mm were cut at right angles to the longitudinal direction of the hot plate, and the maximum stress when peeling off the upper and lower two samples for each test piece was calculated. Average value determined by constant speed extension type tensile tester 0 (5) Delamination durability... Width 25 + ns from sample
, a test piece with a length of 100 mm is set up, and 3
The samples were taken one by one, subjected to a kneading test specified in JIS K632B, and then observed. In addition, the load is 5002
After performing a kneading test 120 times (for 1 minute), it was examined with the naked eye whether or not the sample had delaminated.

〔Effect of the invention〕

The synthetic paper of the present invention has self-adhesive ability and can be bonded (heat-sealed) by thermocompression bonding, and since it is mainly composed of polyester fibers, it has high strength, dimensional stability, and heat resistance. Since both the first and second layers contain low-oriented polyester fibers, delamination can be reliably prevented without using any binder other than the constituent fibers, and the strength of the heat-sealed portion is also extremely high. can do. Therefore, the synthetic paper of the present invention does not cause harmful substances to be leached out by hot water, etc., and is extremely suitable for use in tea bags, coffee filters, etc., and for packaging other products such as desiccant, deodorizing agent, adsorbent, etc. It is also preferably used as

Patent applicant Teijin Ltd.

Claims (1)

[Scope of Claims] (1) A synthetic paper formed by laminating and integrating a first layer made of polyester fibers and a second layer made of fibers and polyester fibers having at least a portion of a low-melting point component; A synthetic paper characterized in that both the layer and the second layer contain 30% by weight or more of low-oriented polyester fibers having a birefringence (Δn) of 0.03 or less. (2) The synthetic paper according to claim (1), wherein the fibers having at least a portion of the low melting point component are polyolefin fibers. (5) The synthetic paper according to claim (1), wherein the fibers at least partially containing a low melting point component are polyester fibers. (4) The synthetic paper according to claims (1) to (6), wherein the 111th polyester fiber is comprised of highly oriented fibers and low oriented fibers.