JPS62299540A - Production of rod-shaped fiber molded body - 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 8. Detailed Description of the Invention Industrial Application Field The present invention is suitable for use in cigarette filters, felt pen ink tanks, water supply rods, etc. i! The present invention relates to a method for manufacturing a rod-shaped fiber molded article having high elasticity and elasticity.

Prior Art and its Problems Japanese Patent Publication No. 59-40938 discloses a method of manufacturing a rod-shaped fiber molded article by heating a polyolefin thermoadhesive composite fiber with high-temperature gas and passing it through a die having a desired cross-sectional shape. There is. According to this method, the fiber bundle is not only heated from the outside by the high-temperature gas, but also heated by the high-temperature gas that passes through the inside of the fiber bundle, so that a rod-shaped fiber molded article can be quickly obtained. Composite fibers are composed of a plurality of different components, and therefore generally have latent crimpability, and crimp occurs upon heat treatment. As this crimp occurs, intertwining occurs between the fibers, making the fiber bundle bulky, and by squeezing with a molding die, a desired cross-sectional shape can be given to the molded product. However, when the above manufacturing method is applied to such composite fibers, the fiber bundle suddenly becomes thicker at the part where the fibers are crimped in the forming machine, and the friction with the vessel wall increases, resulting in a decrease in the take-up tension. Molded products with high fluctuations tend to have density unevenness, rough skin, streaks, etc. In order to prevent the occurrence of crimp in the molding machine, there is a method in which composite fibers are heat treated at a temperature below the molding temperature to cause crimp in advance and then molded.

In such heat treatment, due to the occurrence of crimp (the muslim fiber bundles shrink into a ball-like shape due to entanglement between the muslim fibers), fiber opening treatment is required prior to molding. Therefore, the problem remains that not only the process becomes longer, but also the cost for heat treatment increases.

Among polyolefin composite fibers m, those having crimps caused only by spinning and drawing treatment without heat treatment (such crimping is sometimes referred to as spontaneous crimping) or! There are some that have a machine i4 stick attached, but like this one! No. 11 fibers also undergo crimp due to heat treatment, and the above-mentioned problem remains. Composite fibers that have spontaneous crimp and no latent crimp are also known. However, the crimp elastic modulus of such surface fibers is about 70% and the elastic recovery rate is only about 30%, and when the above manufacturing method is applied to such am, the tensile stress and heating during the molding process cause the curling. As the shrinkage increases, the bulk of the fiber bundle decreases by 30%, and because the repulsive force of the drawing by the forming die is small, the fibers cannot reach every corner with a complex-shaped die, making it difficult to form a molded product with the desired shape. It was difficult to obtain.

Purpose and Structure of the Invention As a result of intensive research to improve the above-mentioned drawbacks of conventional rod-shaped fiber molded articles, the present inventors found that the intended purpose was achieved by using polyolefin composite fibers having specific physical properties as a material. Knowing that this could be accomplished, the present invention was completed.

That is, the present invention heats polyolefin thermoadhesive composite fibers with high-temperature gas and passes them through a molding die to form a rod-shaped fiber molded body with a desired cross-sectional shape, in which the contact points of the fibers are fixed by fusion. In the method of Moreover, this is a method for producing a rod-shaped fiber molded article, which is characterized in that it is used on a polyolefin-based heat-adhesive conjugate fiber having substantially no latent crimpability.

In the present invention, polyolefin thermoadhesive composite fiber is a thermoplastic resin whose first component is a fiber-forming polyolefin such as high-density polyethylene, polypropylene, or poly4-methylpentene-1, and whose melting point is 20°C or more lower than that of the first component. Refers to fibers that are compositely spun into a sheath-core type in which the second component is placed side by side or in a sheath-core type with the second component placed on the sheath side. By heat-treating such fibers at a temperature between the melting points of the two components, a stable molded product is created in which the contact points of the fibers are fused and fixed by the second component without losing their fiber shape. It can be done.

Among such polyolefin composite fibers, there is a special method for obtaining spontaneous crimp with a crimp modulus of 75% or more, an elastic recovery rate of 35% or more, and substantially no latent crimpability. As shown in Japanese Patent Publication No. 58-23915, composite spinning is performed under conditions such that the Q value (= Mpy/MN) after spinning of crystalline polypropylene used as a high melting point component is 8.5 or more. 60 to 7 drawn yarn
By preheating to 0°C, cooling to below the preheating temperature at the end of stretching, and taking it off with nip rolls at 50°C or less, at least one of which is a non-metallic roll, 94~
There is a method of stretching it five times.

The reason why the polyolefin thermoadhesive composite M fiber used in the present invention is limited to those having three-dimensional natural crimp is that fiber bundles of fibers having two-dimensional crimp such as mechanical crimp have poor bulkiness.
The resulting molded product also tends to have low porosity and elasticity, and fibers that have developed latent crimpability through heat treatment require an opening process and increase the cost of heat treatment. . In addition, the crimp elasticity modulus of this composite fiber is 75
%, if the groove is not grooved, the crimp elongation and bulk will be greatly reduced in the molding machine, resulting in a molded body with poor porosity and elasticity, and if the elastic recovery rate is 35%, it is difficult to accurately mold a complex cross-sectional shape. Can not do it.

Here, the crimp modulus refers to the initial load of 519/d (at this time, the collar fiber length a), the after-load of 50 da/d, the fiber length (b)'ft measured after 1 minute, and the fiber length (b)'ft measured without load. The knee 19 elastic recovery rate calculated from the fiber length (c) when an initial load is applied to the page after being left for 1 minute is calculated by laminating 100f square webs of 25α in length and width, and 0.5f/14 When an initial load of Crfld/f>t- is measured, the load is 1114.5
It is determined from the bulk (e d / f ) when the material is left for 24 hours and then left unloaded for 2 hours using the following formula: Elastic recovery rate (%) - XIGO The present invention will be explained below with reference to examples. .

Example 1 The low melting point component was a 1:3 mixture (mp
Ho″C), the high melting point component is crystalline polypropylene (m
9165℃), and the low melting point component accounts for 80% of the fiber cross-sectional circumference.
It is a thermoadhesive composite fiber that accounts for 30% of the total fiber size, has a three-dimensional natural crimp with a crimp modulus of 77% and an elastic recovery rate of 40%, and has a single fiber fineness of 3.
d/f, tow with a total gradient of 60,000 d is injected with 3 kg/d・G steam superheated to 130″C with an inner diameter of 1511 f.
f, fiber bundle introduction tube with length 25ax (total length of injection chamber 421)
The molded material was introduced into a molding machine having a square mouthpiece with one side of 811aR, passed through it at 30 m/min to be heated and molded, and after being air-cooled, it was taken out and cut into 910ffi pieces. This material had a uniform fiber density and appropriate porosity, was highly elastic, had a clean surface, and had a square cross section with sharp corners of 7.9 mm on each side.

Comparative Example 1.2 A conjugate fiber consisting of the same components as in Example 1, which had a three-dimensional natural crimp with a crimp modulus of 76% and an elastic recovery rate of 31% by changing the drawing conditions, and had a single 1a fineness. 3d/f
Using tow with a total fineness of 60,000 denier, a molded article with a square cross section was obtained under the same molding conditions as in Example 1 (Comparative Example 1).

Similarly, a molded article having a square cross section was obtained using tow having a total fineness of 60,000 denier and having a crimp elastic modulus of 71% and an elastic recovery rate of 36% (Comparative Example 2). The molded products obtained in Comparative Examples 1 and 2 had density irregularities, and the center of the side of the rectangular cross-sectional shape was depressed and the four corners were rounded, resulting in poor aesthetic appearance.

Example 2 Low melting point component is high density polyethylene (m2135°C),
The melting point component is crystalline polypropylene (mp165°C)
It is a sheath-core type heat-adhesive composite fiber with a low melting point component as a sheath component, has a three-dimensional natural crimp with a crimp modulus of 75% and an elastic recovery rate of 35%, and has a single fiber count of 22 d/f. A tow with a total fiber fatigue of 50,000 denier was used in Example 1, and was guided to a teleforming machine at 170°.
Inject 3 kg/dG of superheated steam into C, pass it through an equilateral triangular nozzle with sides 10W1I, and add 25 ml mi
The molding was carried out at a speed of n. The obtained molded body had a uniform fiber density, appropriate porosity and elasticity, had a smooth surface, and had an equilateral triangular cross section with sides of 9.9 mm.

Comparative Example 3 A thermoadhesive conjugate fiber having the same composition as in Example 2 and three-dimensional natural crimp with a crimp modulus of 75% and an elastic recovery rate of 33% was used, and the cross section was A triangular molded body was obtained. This product had a hard core inside, a rough surface, and a scalene triangular cross section, so it had low commercial value.

[Brief explanation of drawings]

FIG. 1 is a sectional view conceptually showing a molding machine used in an example of the present application. 1: High temperature gas introduction pipe, 2: Injection chamber, 3: Fiber bundle introduction pipe, 4: Molding die, 5: Take-up roll% 6: Cutting device,
7: Fiber bundle, 8: Rod-shaped fiber molded body or more

Claims (1)

[Claims] (1) In a method for manufacturing a rod-shaped molded article having a desired cross-sectional shape in which a polyolefin-based heat-adhesive composite fiber bundle heated with high-temperature gas is passed through a molding die and the contact points of the fibers are fixed by fusion, a polyolefin-based The heat-adhesive conjugate fiber is characterized by using a heat-adhesive conjugate fiber that has three-dimensional natural crimp with a crimp modulus of 75% or more and an elastic recovery rate of 35% or more, and has no latent crimp property. A method for producing a rod-shaped fiber molded article.