JPS5920699B2 - Method for producing thermoplastic fibers with adhesive ability - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a rewetting hot-melt adhesive molded product that exhibits adhesive performance with water and heat.

Conventionally, polyvinyl alcohol (hereinafter abbreviated as PVA) has a strong intermolecular hydrogen bond in its molecular structure, which makes it difficult to melt under heat.Furthermore, since the melting point of the crystalline region is close to the decomposition temperature, it decomposes at the same time as it melts. This made melt extrusion molding difficult. Therefore, when melt-extruding PVA, it is only possible to melt it by mixing a large amount of plasticizer such as water, or under special conditions as proposed in Japanese Patent Publication No. 38-10362. Ta. However, the former requires a large amount of plasticizer, so if water is used, the resulting molded product will leave foam marks on the surface of the molded product due to boiling of water, and if a plasticizer such as polyhydric alcohol is used, There were problems such as the plasticizer oozing out onto the surface of the molded product, and it was not possible to perform melt extrusion molding as with ordinary general-purpose thermoplastic resins.

Therefore, melt extrusion molding that uses PVA and a large amount of plasticizer in combination is called semi-melt extrusion molding to distinguish it from conventional melt extrusion molding.
Unique technology has been established. On the other hand, in the latter method, PVA with an average degree of polymerization of 1000 or more is melt-spun under pressure in a state excluding air or in an inert gas, but in this case, the melting temperature is high and close to the decomposition temperature of PVA. ,
It is almost impossible to implement industrially because it requires considerably high pressure and has a high melt viscosity.

Therefore, the current methods for manufacturing PVA-based moldings are only wet and dry spinning from an aqueous PVA solution and semi-melt extrusion using water and other plasticizers.

That is, when producing PVA-based fibers, it is impossible to perform melt extrusion molding using PVA alone or using a small amount of plasticizer of 5% by weight or less relative to PVA in the same way as melt extrusion molding of general-purpose thermoplastic resins. It was. On the other hand, PVA-based molded products, that is, PVA-based fibers and films, have been widely used for clothing, industrial materials, etc., but water-soluble fibers and films used for more special purposes, water or hot water swelling There are sexual fibers.

That is, although these are molded products that have adhesive performance that utilizes the hygroscopicity of PVA, all of them utilize water to exhibit adhesive performance, and do not exhibit adhesive performance by being thermally melted. The present inventors have conducted various studies on re-wet hot melt adhesive molded products that exhibit adhesive performance with water and heat, and have found that although conventional PVA cannot achieve such performance, it has an average degree of polymerization of 50 to 300, and Residual acetate group 15~
80 mol% PVA has rewet hot melt adhesive ability;
Furthermore, such special PVA can be melted alone,
Furthermore, the fact that PVA can be melted even if 5% by weight of plasticizer is used, and if the amount of plasticizer used is less than 5% by weight based on PVA, the plasticizer may ooze out on the surface of the resulting molded product. They discovered that there is no problem and completed the present invention.

In other words, the present invention provides a rewetting material having rewetting adhesive performance and heat melt adhesive performance, which is composed of PVA having an average degree of polymerization of 50 to 300, residual acetic acid groups of 15 to 80 mol%, and a plasticizer of 0 to 5% by weight based on the PVA. It is a hot adhesive molded product.

The present invention will be explained in detail.

The PVA used in the present invention has an average degree of polymerization of 50 to 300 and a residual acetic acid group of 15 to 80 mol%, and such PVA completely melts and flows at 140 to 200°C and has stringiness. .

If the average degree of polymerization is less than 50, the spinnability and flexibility of fibers and films will be extremely reduced, making it difficult to form fibers and films. If the degree of polymerization exceeds 300, the melting temperature and viscosity will become too high, resulting in poor spinnability and difficulty in forming a film. If the residual acetate group is less than 15 mol%, it will be difficult to melt, and if it exceeds 80 mol%, the adhesiveness will increase and adhesion will occur between the fibers. Therefore, PVA having an average degree of polymerization of 50 to 300 and a residual acetate group of 15 to 80 mol% is suitable. These P
Once sufficiently dried, VA can be melt extruded on a conventional melt spinning machine.

In that case, melt extrusion conditions such as temperature and speed should be determined based on the PV used.
It may be determined based on the average degree of polymerization of A and the remaining acetic acid groups.
In addition, the spun fibers and formed film are made of PVA using conventional methods.
Unlike fibers and films, it does not need to be dried, and can be treated with oil or stretched in the same way as ordinary melt-extruded thermoplastic resin moldings. In melt extrusion molding, the special PVA alone produces a sufficiently good molded product, but if particularly necessary, a polyhydric alcohol such as polyethylene glycol or a plasticizer such as a urea derivative may be used.

However, if the amount of plasticizer added exceeds 5% by weight, there will be problems such as bleeding on the surface of the resulting molded product, and the performance of the molded product will also deteriorate, so it is necessary to limit the amount to 5% by weight or less. The PVA-based molded product of the present invention obtained in this manner has good adhesive properties.

In particular, a molded product having an average degree of polymerization of 50 to 300 and a residual acetic acid group of 15 to 40 mol% can be bonded by heat and at the same time be easily soluble in water, so that it can exhibit its adhesive ability when treated with water or steam. Furthermore, fibers containing 40 to 80 mol% of residual acetic acid groups exhibit adhesive ability with water, steam, or even heat alone. For example, the PVA fibers obtained according to the present invention are cut to an appropriate fiber length, opened, blended with natural fibers or synthetic fibers, and heated and pressed between rollers to bond the natural fibers or synthetic fibers together. Furthermore, the fibers obtained according to the present invention exhibit effective adhesion ability even to hydrophobic fibers to which it is difficult to obtain sufficient adhesion with ordinary water-soluble PVA fibers (vinylon binder).

As can be seen from these facts, the molded product of the present invention can be used in a very wide range of applications as an adhesive molded product. Hereinafter, the present invention will be explained in more detail with reference to Examples.

Example 1 Chip-shaped P with an average degree of polymerization of 79 and residual acetic acid groups of 42 mol%
After thoroughly drying VA at 60°C under reduced pressure, dry it at 150°C.
Using an extruder with an inner diameter of 3011φ and a length of 45011 mm, the material was melted and spun using a nozzle with a hole diameter of 0.6nφ and 40 holes at a discharge rate of 8y/drive and a spinning speed of 500m/71wt.

The obtained fibers were pale yellow and transparent, and had a fineness of 3.2 denier, a strength of 1.6 f/d, and an elongation of 20.8%. The PVA fibers obtained in this way were cut to a fiber length of 511, spread between two sheets of polypropylene fiber nonwoven fabric, and heated at 130°C.
If you press it with an iron for 10 seconds, it will adhere between the non-woven fabrics,
Its adhesion was good. Further, when hot water at 50° C. was sprayed onto the nonwoven fabrics and the nonwoven fabrics were pressed together with a roller, the nonwoven fabrics were bonded together. Example 2 A PVA chip with an average degree of polymerization of 170 and a residual acetic acid group of 25 mol % was heated at 200°C using the same extruder as in Example 1, and the discharge amount per hole was 0.3 from a nozzle with a hole diameter of 0.5 mmφ.
It was discharged at V/m and wound up at 1000 m/m.

The PVA fiber thus obtained had a single fiber denier of about 2 deniers, a strength of 2.21 V/d, and an elongation of 33.5%. When this PVA fiber was cut into 511 lengths, spread between a sfumos base fabric and aluminum foil, and pressed with an iron at 190° C., it showed good heat sealability. Also,
Good adhesion was also obtained when pressure bonded after steam treatment.

Example 3 PVA chips with an average degree of polymerization of 275 and a residual acetate group of 72 mol% were melt-spun at 200°C in the same manner as in Example 2, and the single fiber fineness was 1.6 denier, strength was 1.847/d, and elongation was 18. ．．
3% PVA fibers were obtained.

Spread these fibers between two sheets of polyester nonwoven fabric for 20 minutes.
The polyester nonwoven fabric was laminated by passing it between rollers heated to 0°C. Spray water on the same nonwoven fabric,
When dried by passing it through a roller, a bond with good adhesion was obtained.

Example 4, Comparative Example 1 Average degree of polymerization 250, residual acetate group 20
Chip-shaped PVA containing 3 parts by weight of glycerin per mol% of PVAlOO is thoroughly dried at 70°C under reduced pressure, and then cut into widths from a T-die using an extruder with a screw diameter of 115~ (L/D=20). A film having a thickness of 40 μm and 500 μm was extruded onto a roller rotating at a circumferential speed of 100 m/min, cooled, and wound up.

The temperature of the T-die of the extruder was 200° C., and the number of revolutions of the screw was 120 rpm. The obtained film did not ooze out the plasticizer glycerin and was transparent.
It had a strength of 0 kg/Cd, an elongation of 180%, and was easily soluble in water at 30°C.

When this film was placed between the polypropylene fiber nonwoven fabrics used in Example 1 and pressed together with an iron at 160°C, the nonwoven fabrics were firmly adhered.

Claims (1)

[Claims] 1. A rewetting hot adhesive having rewetting adhesive performance and heat melting adhesive performance, which is composed of polyvinyl alcohol with an average degree of polymerization of 50 to 300, residual acetic acid groups of 15 to 80 mol%, and a plasticizer of 0 to 5% by weight based on the polyvinyl alcohol. Melt adhesive molded product.