JPS5810493B2 - Kami Oyobi Fushiyokufuyousenino Seizouhou - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing adhesive fibers (binder fibers) that can be used for bonding between fibers constituting paper or nonwoven fabrics. is excellent, and when used as a binder fiber in paper making process,
The object of the present invention is to provide a new method for producing at a low cost an excellent adhesive fiber that greatly improves the tear strength and tear length of the resulting paper or nonwoven fabric, and whose flexibility is not lost due to thermal bonding.

That is, the present invention uses water-soluble and heat-melting polyvinyl alcohol (hereinafter abbreviated as PVA) with an average degree of polymerization of 50 to 300 and residual acetic acid groups of 15 to 50 mol % and an ethylene-vinyl acetate copolymer resin (hereinafter abbreviated as EVA). This is a method for producing paper and nonwoven fibers, which is characterized by mixing the following materials, melt-spinning them, and cutting them.

Since EVA has excellent water resistance and adhesive properties, it has been widely used as a hot melt adhesive in various fields.

However, due to its adhesiveness and flexibility, EVA has the disadvantage that when melt-spun, the fibers tend to adhere while standing, making it difficult to form fibers for practical use.

Conventionally, as a method for manufacturing fibers containing EVA, a method has been proposed, for example, in Japanese Patent Publication No. 47-42050, in which an aqueous emulsion of EVA is mixed with an aqueous PVA solution and wet-spun. The stability of the EVA emulsion is greatly affected by thermal stability, mechanical stability, storage stability, etc., and it is also affected by various factors such as the mechanical stability, flowability, and coagulation of the stock solution mixed with the PVA aqueous solution. This is a method that is difficult to implement industrially due to restrictions.

Furthermore, as long as an aqueous EVA emulsion is used, this wet spinning method is the only method available, but since wet spinning uses a coagulant, it is inevitable that the resulting spun fiber will contain multiple layers of coagulant. Ta.

This is because if the spun fibers are washed with water to remove them, adhesion occurs between the spun fibers, and there are defects that make it difficult to obtain fibers in a dry state.

On the other hand, the use of water-soluble and heat-infusible PVA wet-spun fibers as vinylon binder fibers for paper manufacturing has been well known and widely practiced; however, the vinylon binder fibers are water-soluble. Therefore, it lacks water resistance, and the obtained paper and nonwoven fabric become hard, resulting in poor texture.

In order to solve the problems of the performance of these conventional binder fibers and their manufacturing method, the present inventors believe that EVA can be melt-spun by mixing a water-soluble and heat-melting resin, and the EVA in the formed fibers can be melt-spun. If it is possible to make the adhesive ability of the fiber latent, when this fiber is used in wet paper making, one component of the water-soluble resin will dissolve during paper making and exhibit adhesive ability during drying, and EVAO thermal adhesion ability will also be taken into account, resulting in water resistance and As a result of intensive research and thinking that we could obtain paper with excellent paper strength, we found that a specific PV
The present invention was completed by discovering that A has properties that satisfy these conditions.

Since the present invention involves melt-spinning a mixture of EVA and specific PVA, it is possible to produce EVA that is highly advantageous with conventional wet spinning.
/Does not contain coagulant like PVA binder fiber.

Moreover, the present invention regarding melt-mix spinning of EVA and PVA is a novel method that breaks the conventional wisdom.

The PVA used in the present invention must have an average degree of polymerization of 50 to 300, residual acetic acid groups of 15 to 50 mol %, and be water-soluble and heat-meltable.

If the average degree of polymerization is less than 50, the spinnability in mixed spinning with EVA will deteriorate and at the same time the adhesive strength of the fiber will be extremely reduced, making it unsuitable for the purpose of the present invention.

Furthermore, if the average degree of polymerization of PVA exceeds 300, the melting temperature and viscosity will increase, making melt spinning difficult, which is also unsuitable.

On the other hand, if the residual acetate group in PVA is less than 15 mol%, PVA
The intermolecular bonding force due to the intramolecular and intermolecular hydrogen bonds of the hydroxyl groups becomes strong, the heat meltability deteriorates, and mixing with EVA becomes difficult.

In addition, if the residual acetic acid group exceeds 50 mol%, the solubility of PVA in water deteriorates, and the effect as a binder of the mixed spun fiber with EVA decreases. This is inappropriate because it will no longer be visible.

For these reasons, the PVA used in the present invention has an average polymerization degree of 5.
0 to 300% and 15 to 50% by mole of residual acetic acid groups, which must be water soluble and heat meltable.

Next, EVA, which is mixed and spun with these PVA, or a copolymer of ethylene and vinyl acetate in any ratio can be used, but considering the adhesion as a binder and the flexibility of the paper made, the ethylene content should be 5 to 5. A range of 85% by weight is suitable.

The mixing ratio of these EVA and PVA can be selected arbitrarily, but it is desirable that the EVA content is 15 to 95% by weight from the viewpoint of adhesive strength as a binder, water resistance, and paper strength of paper.

In the present invention, the above-mentioned special PVA and EVA are melt-mixed and spun. At this time, it is also possible to use a tick in which PVA and EVA are uniformly mixed in advance at a temperature higher than their melting points, or they can be spun individually. The mixture may be fed into a machine and spun while being mixed, or a composite nozzle may be used to perform composite spinning using EVA in the core and PVA in the sheath.

Conditions such as temperature, pressure, and speed during melt spinning depend on the P used.
It is sufficient to select an appropriate vortex according to VA and EVA.

Further, the spun fibers are subjected to cold drawing, hot drawing, heat treatment, and oil treatment as necessary, and then cut into fiber lengths suitable for use in paper making, nonwoven fabrics, etc., and used as binder fibers.

The EVA/PVA melt-mixed spun fibers obtained in the present invention can be used to produce paper by wet papermaking from natural pulp, synthetic pulp, or a mixture of the two, or as a binder in the production of wet or, in some cases, dry nonwoven fabric. As a result, it is possible to produce paper or nonwoven fabric with a softer texture and even greater paper strength than conventional products.

EXAMPLES Hereinafter, the present invention will be explained in more detail with reference to examples, and the excellent performance of the binder fiber obtained by the present invention will be shown in experimental examples.

Example 1 PVA2 with an average degree of polymerization of 65 and residual acetic acid groups of 28 mol%
80 parts by weight of EVA having a copolymerization ratio of ethylene and vinyl acetate of 25 near 5 by weight was added to 0 parts by weight, and the mixture was heated at 160°C.
A chip was prepared by melt-mixing.

This step was heated to 200℃ with an inner diameter of 30mLφ and a length of 600m.
Melt spinning was carried out using an extruder.

Spinning was carried out using a nozzle with a nozzle diameter of 0.5 mm Wφ and 60 nozzle holes at a discharge rate of 0.3 g/in per hole and a spinning speed of 1000 n/min.

Then, it was stretched 1.5 times at 70°C, and the white single fiber tenier was 1.6 denier, the strength was 1.83 g/d, and the elongation was 48.7%.
A mixed spun fiber with PVA/EVA=20/80 (weight ratio) was obtained.

This fiber was then cut to obtain a fiber with a fiber length of about 3 mm.

The workability and spinnability of melt spinning were good, and there was no adhesion between the fibers of the resulting mixed fibers.

Example 2 PVA4 with an average degree of polymerization of 172 and residual acetic acid groups of 39 mol%
To 0 parts by weight, 60 parts by weight of EVA with a copolymerization ratio of ethylene and vinyl acetate of 40:60 was added, and using the same spinning machine as in Example 1, the spinning temperature was 200°C, and the nozzle had a pore diameter of 0.6.
mmφ, number of holes: 40, discharge amount: 8? /mrx, spinning speed 5
Spinning was performed at 00 m/min.

The wound fiber was stretched 2.5 times at 80°C, and the white single fiber fineness was 1.2 denier, the strength was 2.18 g/d, and the elongation was 28.
．． A mixed spun fiber with 3% PVA/EVA=40/60 (weight ratio) was obtained.

The fibers were then cut to obtain fibers with a fiber length of approximately 5 mm.

The verbs were good and there was no adhesion between fibers.

Experimental Example 1 The long staple fiber obtained in Example 1 had a fineness of 1.5.
A sample prepared by adding 10% by weight of a binder to polypropylene fiber or rayon fiber having a denier and a fiber length of 5 mm was made into paper with a basis weight of 100 g/i3 using a Tarabee round standard paper machine.

Table 1 shows the results of paper making in the same manner using a commercially available vinylon binder as a comparative sample.

Experimental Example 2 The long cotton fiber obtained in Example 2 was made with a fineness of 1.5.
Denier, polypropylene fibers with a fiber length of 5 mm and rayon fibers with a fiber length of 5 mm are used at a weight ratio of 1:1, and the same propylene fibers and bulbs (NBK
P) was used at a weight ratio of 1:1 and paper was made according to the conditions and method of Experimental Example 1.

As a comparative sample, Table 2 shows the results of paper making in the same manner with the addition of a commercially available vinylon binder.

It is clear from Table 1.2 that when the fibers obtained according to the present invention are used as a binder, paper with excellent paper strength and texture can be obtained.

Claims (1)

[Claims] 1. Water-soluble and heat-melting polyvinyl alcohol with an average degree of polymerization of 50 to 300 and residual acetic acid groups of 15 to 50 mol % and an ethylene-vinyl acetate copolymer resin are mixed, melt-spun, and cut. Process for producing fibers for paper and nonwovens.