JPH02182964A - Heat-treatment of nonwoven fabric - Google Patents

Abstract

PURPOSE:To carry out uniform and continuous shrinkage treatment of a nonwoven fabric by providing a heat-treatment tank containing a liquid heating medium and having a delivery roller at the outlet side and a feed roller at the inlet side and setting the circumferential speed of the delivery roller to be lower than that of the feed roller by an amount corresponding to the shorten ing of the length caused by free shrinkage with heat. CONSTITUTION:A nonwoven fabric is continuously introduced into a heat- treatment tank containing a liquid heating medium through a feed roller attached to the inlet-side and subjected to shrinking heat-treatment. In the above process, the circumferential speed of a delivery roller attached to the outlet-side of the heat-treatment tank is set to be lower than that of the feed roller by an amount corresponding to the shortening of the length caused by free shrinkage of the nonwoven fabric with heat. A uniform shrinkage heat- treatment can be carried out while minimizing the tension applied to the fabric.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a heat treatment method for uniformly shrinking a nonwoven fabric.

[Prior Art] A method of improving fiber density and strength by passing a wide needle-punched nonwoven fabric having heat shrinkability through a liquid heating medium such as hot water and continuously shrinking the fabric is known.

In order to prevent the occurrence of wrinkles due to uneven shrinkage in the center and edges of the fabric during this process, a method has been proposed in which the contraction start positions of the two are differentiated to ensure uniform contraction (
Special Publication No. 49-41506, Special Publication No. 53462-1982).

[Problems to be Solved by the Invention] In the above heat treatment method, a feed roller provided at the entrance side of a heat treatment tank containing a heating medium continuously feeds the nonwoven fabric into the tank, and a pull-out roller provided at the exit side feeds the nonwoven fabric into the tank. In the configuration in which the nonwoven fabric is pulled out from the sieve, it is difficult to make the nonwoven fabric completely tension-free, and although lateral shrinkage progresses sufficiently at both ends, lateral shrinkage is suppressed at the center, causing the nonwoven fabric to shrink between both ends and the center. There was a problem in that there was a difference in shrinkage between the parts, causing wrinkles and variations in quality.

The present invention aims to solve these problems.

[Means for Solving the Problems] In order to solve the above problems, the present invention employs the following configuration.

That is, the heat treatment method for a nonwoven fabric according to the present invention is a heat treatment method in which a nonwoven fabric is continuously introduced into a liquid heating medium and shrunk. At the same time, a pull-out roller is provided on the exit side to pull out the non-woven fabric from the heat treatment tank, and the circumferential speed of the pull-out roller is increased by an amount corresponding to the decrease in length due to shrinkage of the non-woven fabric in a free state where no tension is applied. It is characterized by processing at a speed slower than the circumferential speed of the roller.

If the nonwoven fabric is contracted in a free state without any tension, there will be no difference in shrinkage between the ends and the center, so in the present invention, the peripheral speed of the feed roller is set faster than the peripheral speed of the pull-out roller. This prevents the occurrence of differential shrinkage by minimizing the application of tension to the nonwoven fabric.

FIG. 1 shows an example of an apparatus used for carrying out the present invention. This heat treatment apparatus 1 includes a heat treatment tank 2, and nip rollers for feeding the workpiece are provided on the inlet and outlet sides of the tank 2, respectively. A pair of upper and lower rollers provided on the artificial side of the heat treatment tank 2 are feed rollers 3, and a pair of upper and lower rollers provided on the exit side are pull-out rollers 4.

The heat treatment tank 2 contains a liquid heating medium such as hot water 5 at 95°C. The heating medium may also be other liquids. Also,
A submerged roller 6 is rotatably supported inside the heat treatment tank 2 . The nonwoven fabric S is sandwiched between the feed rollers 3, guided into the hot water 5 by the rotation of the feed rollers, and then pulled out by the pull-out rollers 4 via the submerged rollers 6. At this time,
The liquid-containing nonwoven fabric is squeezed by the squeezing force of the pull-out roller 4.

In this device 1, the feed roller 3 and the pull-out roller 4 are driven by a motor 7, and the drive system of the feed roller 3 is provided with a continuously variable transmission 8.
The peripheral speed can be freely adjusted. When heat-treating a nonwoven fabric, the circumferential speed v1 of the feed roller 3 is set higher than the circumferential speed v2 of the pull-out roller 4, and the speed ratio between the two is such that the nonwoven fabric S, which is the processed material, is kept under tension in the same heating medium. The size is set to match the shrinkage ratio when contracted in a free state. For example, when a needle-punched nonwoven fabric is contracted in a free state in hot water, the area shrinkage rate is usually 20 to 26%, and in this case, the preferable circumferential speed ratio Vl/V2 is l, 12 to 1.16. be.

For example, good results were obtained when the peripheral speed of the feed roller 3 was 5.65+o/min and the peripheral speed of the pull-out roller 4 was 5.0 m/min.

Furthermore, in order to further reduce variations in shrinkage, it is desirable to make the distance from the pull-out roller 4 to the liquid surface of the heating medium 5 and the distance #L2 from the submerged roller 6 to the liquid surface as short as possible. The reason for this is thought to be that when Ll is shortened, the load applied to the nonwoven fabric due to the weight of the liquid (hot water) it contains is reduced, and when L2 is shortened, the resistance it receives in the liquid is reduced. . In the illustrated example device, it was effective to set L to 20 cm or less, more preferably 15 cm or less. Further, L2 is preferably 25 cm or less, and more preferably 15 cm or less.

[Example] Using the apparatus shown in FIG. 1, V, = 6.6 m/min, V,
/V2=1. ! 4, L, =, I5c+n, L2=
]Ocm [When a needle-punched non-woven fabric of 16 cm was previously treated, the width of the non-woven fabric was reduced to I by this heat treatment.
02+=n, and there was no variation in width and thickness. Further, the area shrinkage rate was 23.1%. The treated nonwoven fabric was led to a PVA impregnation tank, impregnated, and then dried. The PVA adhesion rate was as good as 40%, and the Gurley stiffness (JIS L 1096) was 1000 to 1300 (
mg), which was good.

[Effects of the Invention] As is clear from the above description, the nonwoven fabric heat treatment apparatus according to the present invention can perform shrinkage with as little tension as possible, thereby reducing variations in quality.

It is clear that this heat treatment apparatus can be used for similar heat treatment of sheet-like fiber aggregates made of natural mM, synthetic fibers, etc. other than nonwoven fabrics.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram illustrating an example of a heat treatment apparatus used in carrying out the present invention.

Claims (1)

[Claims] (1) In a heat treatment method in which a nonwoven fabric is continuously introduced into a liquid heating medium and shrunk, a feed roller for feeding the nonwoven fabric is provided on the entrance side of a heat treatment tank containing the heating medium, and a nonwoven fabric is placed on the exit side of the heat treatment tank containing the heating medium. A pull-out roller is provided to pull out the nonwoven fabric from the heat treatment tank, and the circumferential speed of the pull-out roller is made slower than the circumferential speed of the feed roller by an amount commensurate with the reduction in length due to shrinkage of the nonwoven fabric in a free state where no tension is applied. 1. A method for heat treating nonwoven fabric, which comprises performing a treatment.