JP2915042B2 - Cotton wool nonwoven fabric for cushion material and method for producing the same - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a cotton wool nonwoven fabric for cushioning materials, and more particularly to cushioning materials that can be suitably used as cushioning materials for furniture, vehicles, beddings and the like. The present invention relates to a cotton wool nonwoven fabric.

(Prior Art) Conventionally, as a nonwoven fabric for cushioning materials, a nonwoven fabric made of a large-sized apparently crimped fiber manufactured by a needle punching method has been known. However, this non-woven fabric
Usually, it has a problem that it tends to be bulky. As a method of suppressing bulkiness, there is a method of increasing a needle punch density, but there is a problem that productivity is reduced. In addition, in this nonwoven fabric, the arrangement of the fibers constituting the nonwoven fabric is perpendicular to the direction of the compressive force (side-by-side), so that the fatigue of crimping, so-called settling, is fast, and the performance evaluation item as a cushion material made of urethane foam. There is a problem that the repetition compression residual distortion rate in JIS K 6401 increases.

On the other hand, nonwoven fabrics manufactured by a thermal bonding method in which low melting point fibers are mixed instead of the needle punch method are known. This non-woven fabric uses an apparent crimped fiber and a latent crimped fiber, and the resulting non-woven fabric has a problem that it tends to be bulky, though the repetition compression residual strain is as large as about 10 to 15%. doing. There are various methods for suppressing bulkiness, such as a method of increasing the amount of low-melting fiber mixed, a method of heat treatment at a high temperature, and a method of changing the fineness, but the resulting nonwoven fabric becomes harder by any of these methods. However, there is a problem that the residual strain rate due to repeated compression increases and the function as a cushion material is lacking.

(Problems to be Solved by the Invention) The present invention solves the above-mentioned problems in the nonwoven fabric produced by the thermal bonding method, and has excellent compression recovery properties, a small rate of repeated compression residual strain, excellent uniform moldability, and is complicated. It is an object of the present invention to provide a cotton wool nonwoven fabric for cushion material which can be easily formed into a simple structure and can be suitably used as a cushion material for furniture, vehicles, beddings and the like, and a method for producing the same.

(Means for Solving the Problems) As a result of intensive studies to solve the above problems, the present inventors have reached the present invention. That is, the present invention relates to: 1. 50 to 99% by weight of a fiber which expresses a high degree of crimp of 50 to 150 pieces / 25 mm by heat treatment of the latently crimpable fiber and the melting point of the latently crimpable fiber. A nonwoven fabric obtained by compression-molding an ingot containing at least 1 to 50% by weight of a binder fiber having a softening point lower by at least 20 ° C, and having an apparent density of 10 to 49.
kg / m ³ and a cyclic compression residual strain of 8% or less, a cotton wool nonwoven fabric for cushioning material, 2. 50 to 99% by weight of latently crimpable fiber having low crimp; At least 20 above the melting point of the latently crimpable fiber having a low crimp
A lump containing 1 to 50% by weight of a binder fiber having a low softening point is formed, and the lump is passed through the following manufacturing process A and heat-treated to form the latently crimpable fiber having a low crimp. A method for producing a cotton wool nonwoven fabric for cushioning material, comprising: developing a high degree of crimp, cooling the binder fiber to a temperature below the softening point thereof while maintaining the compressed state, and taking out the molded nonwoven fabric. After heating the cotton wool ingot to a temperature at which the binder fiber softens and has a high degree of crimp in the latently crimpable fiber having a low crimp, compression molding is performed at a temperature higher than the softening point of the binder fiber, or After compression molding of the cotton wool ingot at a temperature lower than the softening point of the fiber, the binder fiber is softened while maintaining the compressed state, and heated to a temperature at which the highly crimped latent crimpable fiber with low crimp develops. The process is a gist.

 Next, the present invention will be described in detail.

The cotton wool nonwoven fabric for cushioning material according to the present invention is obtained by heating the latently crimpable fibers to 50 to 150 fibers / 25 mm by expressing a high degree of crimp, and 50 to 99% by weight of binder fibers. % Of the cotton wool ingot is compression-molded.

The latently crimpable fiber having a low crimp, which is a raw material component of the cotton wool nonwoven fabric for cushioning material of the present invention, is a latently crimpable core-sheath composite fiber or a side-by-side composite fiber composed of a polyester or polyolefin polymer. It is a conjugate fiber, and in particular, a polyester-based conjugate fiber is preferable because it not only has excellent compression recovery properties but also expresses latent crimp satisfactorily due to a difference in shrinkage during dry heat or wet heat treatment. The latently crimpable fiber has a number of crimps of about 8 to 15 pieces / 25 mm and a single yarn fineness of
0.5 to 40 denier, cut length 5 to 100 mm, preferably 20
~ 80mm. Further, the binder fiber as another raw material component is at least a melting point of the latently crimpable fiber.
It is a fiber having a softening point lower by 20 ° C. and is a polyethylene-based, polypropylene-based, isophthalic acid-copolymerized polyethylene terephthalate fiber, or a core-sheath type composite fiber whose sheath component is a low-melting polymer. The binder fiber has a single fiber fineness of 0.5 to 40 denier, preferably 1.5 to 15 denier.
Denier's.

The cotton material nonwoven fabric of the present invention is 50 to 99% by weight.
The latent crimpable fiber having a low crimp of the above and the latent fiber having a low crimp while softening the binder fiber when a cotton wool ingot containing 1 to 50% by weight of the binder fiber is heat-treated. When a high crimp of 50 to 150 pieces / 25 mm is developed, the apparent density is compression molded to 10 to 49 kg / m ³ .

The cotton wool nonwoven fabric for cushioning material of the present invention has an apparent density of 10 to 49 kg / m ³ and a repetitive compression set of 8% or less. This repeated compression residual strain rate is JIS K 6401 (soft urethane foam for cushion)
After measuring the thickness of the cotton wool nonwoven fabric, the nonwoven fabric is sandwiched between parallel flat plates, and the compression strain with a compression strain rate of 50% is continuously repeated at a compression speed of 60 times / minute at room temperature. After applying 8000 times, the non-woven fabric was taken out, left to stand for 30 minutes, its thickness was measured, and the difference in the thickness divided by the initial thickness was expressed as a percentage. That is, the repetition compression residual strain rate indicates how much the thickness after repetition compression is lower than the original thickness, and the smaller the strain rate is, the better the performance of the nonwoven fabric is.

The cotton wool nonwoven fabric for cushioning material of the present invention has a low crimping potential crimping fiber of 50 to 99% by weight, preferably 70 to 90% by weight, based on the melting point of the low crimping potential crimping fiber. It is produced by compression molding of a cotton wool lump containing 1 to 50% by weight, preferably 10 to 30% by weight of a binder fiber having a softening point lower by at least 20 ° C. When the latent crimpable fiber is less than 50% by weight and the binder fiber exceeds 50% by weight,
The cyclic compressive residual strain of the cotton nonwoven fabric is higher than 8%, and the cushioning property cannot be improved, which is not preferable.

The cotton wool nonwoven fabric for cushioning material of the present invention has a repetitive compression set of 8% or less of the nonwoven fabric. It needs to be 10 to 49 kg / m ³ , preferably 20 to 30 kg / m ³ . If the apparent density of the cotton non-woven fabric is less than 10 kg / m ³ , when the non-woven fabric is compressed, the degree of freedom between the balls constituting the non-woven fabric becomes too large, and the fatigue of the ball shape is accelerated. Since the ratio becomes higher than 8% and becomes extremely thin with respect to the original bulk before repeated compression, it cannot be suitably used as a cushioning material. On the other hand, when the apparent density exceeds 49 kg / m ³ , the degree of freedom between the bamboo composing the nonwoven fabric decreases, but the space required for the compression recovery is small, so that the repetitive compression residual strain rate is higher than 8%. Since it becomes extremely thin with respect to the original bulk before repeated compression, it cannot be suitably used as a cushion material.

The method for producing a cotton wool nonwoven fabric for cushioning material according to the present invention comprises the following steps: first, a low crimped latently crimpable fiber of 50 to 99% by weight, preferably 70 to 90% by weight; A lump of lint containing 1 to 50% by weight, preferably 10 to 30% by weight, of a binder fiber having a softening point at least 20 ° C lower than the melting point of the conductive fiber is prepared. Next, heat treatment is performed on the cotton wool lump containing the latently crimpable fiber having low crimp and the binder fiber. This heat treatment is performed in the manufacturing process A. In the production step A, the cotton wool ingot is heated to a temperature at which the binder fiber is softened and the highly crimped latent crimpable fiber has a high degree of crimp, and then compressed at a temperature equal to or higher than the softening point of the binder fiber. After forming or compressing and molding the cotton wool ingot at a temperature lower than the softening point of the binder fiber, the binder fiber softens while maintaining the compressed state, and is highly crimped into a latently crimpable fiber having low crimp. Is a step of heating to a temperature at which When heat-treating the above-mentioned lump of cotton containing the latently crimpable fiber having low crimp and the binder fiber to express high crimp, the latent crimp of the fiber is easily developed and the binder in the lump of cotton. In order to improve the thermal efficiency to the fiber, it is recommended to use a net conveyor type thermal through type hot air circulation type heat treatment machine. The air volume of this hot air circulation type heat treatment machine is 15-50m ³ /
Minutes. In order to compress and shape the nonwoven fabric, a moving belt type holding device having a cooling function is provided immediately after the heat treatment machine. As the belt-type pressing device, a device including a plurality of rollers can be used. At this time, the roller interval should be such that the compression ratio with respect to the bulk density of the cotton wool ingot is 50 to 90%. Also,
The heat treatment temperature is set to a temperature at which the binder fiber softens and latent crimps are highly developed. Usually, the temperature is 10 to 60 ° C higher than the softening point of the binder fiber. If the heat treatment temperature is higher than the softening point by 60 ° C. or more, the binder fibers are melted, and the obtained nonwoven fabric becomes hard, and the texture is unfavorably deteriorated.

Next, the heat-treated lint is cooled to a temperature equal to or lower than the softening point of the binder fiber while maintaining its compressed state, and then the molded non-woven fabric is taken out to be a lint-free non-woven fabric.

In cooling the ingot after heat treatment, it is necessary to cool the binder fiber to a temperature lower than the softening point of the binder fiber while maintaining the compressed state, following the heat treatment. Upon cooling to open the compressed state, it can not be repeated compression residual strain ratio excellent cushion property at 8% or less, and apparent density obtain Tamawata nonwoven is 10~49kg / m ^3, is not preferred.

In the present invention, an apparently crimped fiber having a crimp in a part of the latently crimpable fiber may be used. As the latently crimpable fibers, fibers of different fineness or mixed cut length can also be used. If the lint as a raw material for the nonwoven fabric contains the above-mentioned weight% of the latently crimpable fiber and the above-mentioned weight% of the binder fiber, the nonwoven fabric of the present invention can be obtained. Further, in the above-mentioned manufacturing process, the cotton wool ingot may be heated and compressed and cooled by a mold or the like to be compression-molded, or the cotton wool nonwoven fabric of the present invention may be formed again. Further, for example, it may be integrally formed into a seat shape, furniture shape, bedding shape, or the like of a vehicle.

(Example) Next, the present invention will be specifically described based on examples.
Various characteristics in the examples were measured by the following methods.

Melting point (° C): Using a Mettler microscope melting point measuring apparatus, two fibers are placed on a hot stage with crossing each other, and the intersection of the fibers is deformed when the temperature is raised at a rate of 2 ° C / min. The melting temperature was determined, and this was taken as the melting point.

Softening point (° C): Using a Mettler microscope melting point analyzer, two fibers are placed on a hot stage with crossing each other, and when the temperature is raised at a rate of 2 ° C / min, the intersection of the fibers becomes The temperature at which deformation starts was determined and used as the softening point. When the fibers consisted of two-component polymers having different softening points, the temperature on the low temperature side was regarded as the softening point.

Dimensions (thickness) (mm): Use a measuring instrument with a minimum scale of 1 mm or less according to the method described in JIS K 6401-5-2. The average was determined.

Apparent density (kg / m ³ ): Measure the dimensions of the sample according to the method described in JIS K 6401-5-3 to determine the volume V (mm ³ ). Using sample mass M
(G) up to 0.1 g, and the apparent density D (kg
/ m ³ ) was calculated.

D = (M / V) × 10 ⁶ … Repeated compression residual strain rate (%): JIS K 6401-5-6
After measuring the thickness t ₀ (mm) of the sample according to the method described in (1), the sample is sandwiched between parallel flat plates.
After applying a compressive strain with a compressive strain rate of 50% continuously at a compressing speed of 80,000 times, the sample piece is taken out and left for 30 minutes, and its thickness t ₁ (mm) is measured. The compression set C (%) was calculated.

C = [(t ₀ −t ₁ ) / t ₀ ] × 100 Compressive stress (kg): A sample piece prepared by cutting a nonwoven fabric into 10 cm × 10 cm is prepared, and a compression test of the sample piece is performed using a compression tester. Was carried out, and a compression curve as shown in FIG. 1 was drawn to determine a compression stress X ₁ (kg).

Compression recovery rate (%): In the compression test, a compression curve as shown in FIG. 1 was drawn, areas A and B were obtained, and the compression recovery rate (%) was calculated by the following equation.

Compression recovery = [B / (A + B)] × 100 Thermoformability: As shown in FIG. 2 (1), the sample 1 was bent and fixed to a jig 2 at an angle of 90 deg. After a heat treatment for 5 minutes, the mixture was left to cool at room temperature for 5 minutes. After cooling, the sample piece 1 was taken out of the jig 2 and the angle θ (deg) of the thermoformed sample piece 1 as shown in FIG. 2 (2) was measured to evaluate the thermoformability.

Example 1 As a latently crimpable fiber, 80% by weight of a side-by-side type polyester-based composite fiber having a melting point of 256 ° C., a single yarn fineness of 2 denier, a cut length of 51 mm, and a number of crimps of 14/25 mm,
Core-sheath type polyester composite fiber with a softening point of 100 ° C, single yarn fineness of 2 denier and a cut length of 38 mm as binder fiber
Using 20% by weight, stirring for 1 minute under a high-speed air flow to make a cotton wool I having a diameter of about 2 mm,
× The product was placed in a plastic frame with a depth of 30 cm and one side of which was shaped like a door, and an apparent density of 5.7 kg / m ³ was obtained. The obtained ingot had a low density and an aggregate of ingots without adhesion inside. After compressing the ingot at room temperature at a compression ratio of 71.9%, the frame was removed, and a heat treatment was performed using a hot air circulating drier while maintaining the compressed state. The processing conditions were a temperature of 140 ° C., an air volume of 8 m ³ / min, and a processing time of 10 minutes.

Next, the lint is removed from the dryer, and while maintaining the compressed state, is cooled at room temperature to a temperature lower than the softening point of the binder fiber so that the ratio of the bulk density of the nonwoven fabric to the lump density of the lint becomes 28.1%. A compression-formed sheet-like heat-bonded cotton nonwoven fabric was obtained.

The obtained sheet-like heat-bonded cotton nonwoven fabric has a thickness of 3.5 mm,
The apparent density was 20.3 kg / m ³ . Table 1 shows the characteristics of the cotton wool nonwoven fabric.

Example 2 As a latently crimpable fiber, 70% by weight of a side-by-side type polyester-based composite fiber having a melting point of 256 ° C., a single yarn fineness of 10 denier, a cut length of 38 mm, and a number of crimps of 10/25 mm,
Core-sheath polyester composite fiber with a softening point of 100 ° C, a fineness of single yarn of 4 denier and a cut length of 38 mm as a binder fiber
Using 30% by weight, agitate for 2 minutes in a high-speed air stream to make a cotton ball II with a diameter of about 6 mm.
× placed in a stainless steel cage with a depth of 30 cm and one side being door-shaped, an apparent density of 5.8 kg / m ³ was obtained. The obtained ingot had a low density and an aggregate of ingots without adhesion inside. The first heat treatment was applied to the ingot with the basket using a hot air circulation dryer. The processing conditions were a temperature of 140 ° C. and a processing time of 7 minutes. Continuously, in the above dryer, the bamboo lump is compressed at 69.9%.
Then, a second heat treatment was performed. The processing conditions were a temperature of 140 ° C. and a processing time of 3 minutes.

Next, the lint is taken out of the dryer, and while maintaining the compressed state, is cooled at room temperature to a temperature lower than the softening point of the binder fiber. To give a sheet-like heat-bonded cotton nonwoven fabric which was compression-molded to 30.1%.

The resulting sheet-like thermally bonded cotton nonwoven fabric has a thickness of 3.6 mm.
The apparent density was 19.3 kg / m ³ . Table 1 shows the characteristics of the cotton wool nonwoven fabric.

Comparative Example 1 As a latently crimpable fiber, 40% by weight of a side-by-side type polyester composite fiber having a melting point of 256 ° C., a single yarn fineness of 2 denier, a cut length of 51 mm, and a number of crimps of 14/25 mm,
Core-sheath type polyester composite fiber with a softening point of 100 ° C, single yarn fineness of 2 denier and a cut length of 38 mm as binder fiber
Using 60% by weight, agitated for 3 minutes in a high-speed air stream to produce a cotton wool III having a diameter of about 2 mm. In the same manner as in Example 1, a cotton wool lump having an apparent density of 5.7 kg / m ³ was obtained. Obtained. The gill-obtained lump was a low-density, aggregated form of lint-free inside. After compressing the ingot at a compression rate of 71.5% at room temperature, a heat treatment is performed using a hot air circulating drier while maintaining the compressed state, and then, while maintaining the compressed state, the binder fiber is cooled at room temperature at room temperature. When cooled to below the softening point, the ratio of the bulk density of the nonwoven fabric to the bulk density of
% Of a sheet-like heat-bonded cotton wool nonwoven fabric.

The obtained sheet-like heat-bonded cotton nonwoven fabric has a thickness of 3.5 mm,
The apparent density was 20.0 kg / m ³ . Table 1 shows the characteristics of the cotton wool nonwoven fabric.

Comparative Example 2 Using the cotton wool I obtained in Example 1, the compression ratio was 40.1%.
A sheet-like heat-bonded cotton nonwoven fabric having a thickness of 3.6 mm and an apparent density of 9.5 kg / m ³ was obtained in the same manner as in Example 1 except that the above conditions were satisfied. Table 1 shows the characteristics of the cotton wool nonwoven fabric.

Comparative Example 3 Using the cotton wool lump I obtained in Example 1, the compression ratio was 89.5.
%, A sheet-like heat-bonded cotton nonwoven fabric having a thickness of 3.6 mm and an apparent density of 53.3 kg / m ³ was obtained in the same manner as in Example 1. Table 1 shows the characteristics of the cotton wool nonwoven fabric.

Example 3 As a latently crimpable fiber, 80% by weight of a side-by-side type polyester composite fiber having a melting point of 256 ° C., a single yarn fineness of 6 denier, a cut length of 38 mm, and a number of crimps of 13/25 mm,
Core-sheath type polyester composite fiber with a softening point of 100 ° C, single yarn fineness of 2 denier and a cut length of 38 mm as binder fiber
Using 20% by weight, mix evenly with a roller card and stir under high-speed air flow for 2 minutes to make a 4 mm diameter cotton wool I.
V was made, and this cotton wool IV was blown from a hopper into a way pan placed in front of a net conveyor type hot air circulation heat treatment machine, weighed a predetermined amount, and dropped on a net conveyor of the heat treatment machine. The apparent density is reduced to 1 by forcibly pushing the paper into the temporary pressure roller placed immediately before the heat treatment machine.
2.3 kg / m ³ of lint was obtained, and then supplied to a heat treatment machine via a temporary pressure roller to subject the lint to heat treatment. The processing conditions were a temperature of 150 ° C, an air volume of 50 m ³ / min, a processing speed of 8 m / min,
The processing time was 1.9 minutes.

Then, following the heat treatment, a movable belt type holding device with a cooling function having a pair of upper and lower belts disposed immediately after the heat treatment machine until the temperature of the cotton wool ingot falls below the softening point of the binder fiber. Using, the cotton wool lump compresses 60.0%
% Of the nonwoven fabric is cooled out of the softening point of the binder fiber at room temperature while maintaining the compressed state. A sheet-shaped heat-bonded cotton nonwoven fabric having a compression ratio of 40.0% was obtained.

The obtained sheet-like thermally bonded cotton nonwoven fabric has a thickness of 3.8 mm.
Apparent density was of 30.8kg / m ^3. Table 1 shows the characteristics of the cotton wool nonwoven fabric.

Example 4 150% by weight of the cotton wool obtained in Example 1 and 50% by weight of the cotton wool IV obtained in Example 3 were mixed, and the apparent cotton wool lumps output from the temporary pressure roller disposed immediately before the heat treatment machine. except that the density was 12.3 kg / m ^3, in the same manner as in example 3, a thickness of 3.8 mm, apparent density
A sheet-like heat-bonded cotton nonwoven fabric of 32.2 kg / m ³ was obtained. Table 1 shows the characteristics of the cotton wool nonwoven fabric.

Example 5 As a latently crimpable fiber, 60% by weight of a side-by-side type polyester composite fiber having a melting point of 256 ° C., a single fiber fineness of 2 denier, a cut length of 51 mm, and a crimp count of 14/25 mm was softened as a binder fiber. The point is 100 ℃, the fineness of single yarn is 2 denier,
Using 20% by weight of core-sheath type polyester-based composite fiber with a cut length of 38 mm, mixed with 20% by weight of a side-by-side type polyester hollow composite fiber with a single-fiber fineness of 6 denier and a cut length of 38 mm. Stir for a minute and the diameter is about 6mm
Create a piece of cotton wool V, and put this cotton wool 25 cm long x 25 cm wide x depth
One side was placed in a frame made of plastic became door shape in 30 cm, an apparent density was obtained balls of cotton mass of 5.2 kg / m ^3. The obtained ingot had a low density and an aggregate of ingots without adhesion inside. After compressing the ingot at a compression rate of 74.3% at room temperature, the frame was removed, and a heat treatment was performed using a hot air circulating drier while maintaining the compressed state.

 The processing conditions were the same as those in Example 1.

Next, the lint is removed from the dryer, and while maintaining the compressed state, cooled at room temperature to the softening point of the binder fiber or lower, and the ratio of the bulk density of the nonwoven fabric to the bulk density of the lint becomes 25.7%. A compression-formed sheet-like heat-bonded cotton nonwoven fabric was obtained.

The obtained sheet-like heat-bonded cotton nonwoven fabric has a thickness of 3.5 mm,
The apparent density was 20.2 kg / m ³ . Table 1 shows the characteristics of the cotton wool nonwoven fabric.

Example 6 As a latently crimpable fiber, 80% by weight of a side-by-side type polyester composite fiber having a melting point of 256 ° C., a single yarn fineness of 2.5 denier, a cut length of 51 mm, and a number of crimps of 15/25 mm,
Core-sheath type polyester composite fiber with a softening point of 100 ° C, single yarn fineness of 2 denier and a cut length of 38 mm as binder fiber
Using 20% by weight, agitate for 1 minute under high-speed air flow to make a cotton wool VI having a diameter of about 2 mm.
× The product was placed in a plastic frame with a depth of 30 cm and one side being door-shaped, and an apparent density of 5.5 kg / m ³ was obtained. The obtained ingot had a low density and an aggregate of ingots without adhesion inside. After compressing this cotton wool lump at room temperature at a compression ratio of 73.7%, the frame was removed, and heat treatment was performed using a hot air circulating drier while maintaining the compressed state.
The latent crimp of the latently crimpable fiber was developed. The processing conditions were the same as those in Example 1 except that the temperature was set to 150 ° C. Due to the heat treatment, crimps with a number of crimps of 80/25 mm were developed.

Next, the lint is taken out of the dryer and, while maintaining the compressed state, is cooled to a temperature lower than the softening point of the binder fiber at room temperature, and the ratio of the bulk density of the nonwoven fabric to the lump density of the non-woven cloth becomes 26.3%. A compression-formed sheet-like heat-bonded cotton nonwoven fabric was obtained.

The obtained sheet-like heat-bonded cotton nonwoven fabric has a thickness of 3.4 mm,
The apparent density was 20.9 kg / m ³ . Table 1 shows the characteristics of the cotton wool nonwoven fabric.

The cotton wool nonwoven fabrics of Examples 1 to 4 have a small repetitive compression residual strain rate of 8% or less, a high compression recovery rate of about 66 to 73%, and a compressive stress of about 4 kg. Thus, it has a moderate flexibility.

The cotton wool nonwoven fabric of Comparative Example 1 has the same apparent density as that of the nonwoven fabrics of Examples 1 and 2, but has only 40% by weight of fibers having latent crimps. Since the binder fibers are mixed in a large amount of 60% by weight, the fibers are firmly bonded by heat treatment to form an extremely hard nonwoven fabric. The repetition compression residual strain rate is as high as 12.4%, the compression recovery rate is as low as 50.2%, and the cushion material is It cannot be used as a cotton wool nonwoven fabric.

The cotton wool nonwoven fabric of Comparative Example 2 was made of the same material as that of Example 1, but was softened because the apparent density was reduced to 9.5 kg / m ^3, and the compressive residual strain rate was 8.6.
%, And the compression recovery rate is as low as 56.3%, so that it cannot be used as a cotton wool nonwoven fabric for cushioning materials.

The cotton wool nonwoven fabric of Comparative Example 3 was also made of the same material as that of Example 1, but the apparent density was too high at 53.3 kg / m ³ , so the repetition compression residual strain rate was as high as 10.1% and the compression recovery rate was low.
It is as low as 55.1% and cannot be used as a cotton wool nonwoven fabric for cushioning materials.

The cotton wool nonwoven fabric of Example 5 was made from cotton wool containing latent crimpable fiber, binder fiber and non-crimpable fiber, and the latent crimpable fiber was mixed at 60% by weight. Therefore, the cyclic residual strain rate is as small as 4.9%, the compression recovery rate is as high as 71.5%, and the compressive stress is about 3.
As is clear from the fact that it weighs 5 kg, it has moderate flexibility.

The cotton wool nonwoven fabric of Example 6 has a residual compression set rate of
As small as 2.8%, the compression recovery rate is as high as 73.0%, and the compressive stress is 3.7kg, as is clear from the fact that it has moderate flexibility.

(Effect of the Invention) The cotton wool nonwoven fabric for cushioning material of the present invention is a nonwoven fabric obtained by compression-molding a cotton wool lump containing latent crimpable fibers and a binder fiber having a softening point lower than the melting point of the latent crimpable fibers. Yes, since the constituent fibers form a ball-shaped aggregate and are oriented three-dimensionally in random directions, they have excellent compression recovery, low residual compression residual strain, and are formed into massive aggregates. Before heat treatment, the entanglement between massive aggregates is smaller than that of short fiber webs, so that it has excellent uniform moldability and can be easily formed into a complicated structure. And it can be suitably used as cushioning material for furniture, vehicles, beddings and the like.

According to the production method of the present invention, the cotton nonwoven fabric for cushion material can be easily produced.

[Brief description of the drawings]

FIG. 1 is a diagram for explaining a method of obtaining a compressive stress and a compression recovery rate from a compression curve obtained in a compression test of a cotton wool nonwoven fabric, and FIG. 2 is a diagram illustrating a method of evaluating thermoformability of a cotton wool nonwoven fabric. FIG. 1: Sample of non-woven cotton fabric, 2: Jig

Claims (3)

(57) [Claims] (1) heating the latently crimpable fiber by 50-150.
50/99% by weight of fiber with high crimp of 25mm
A nonwoven fabric obtained by compression-molding a cotton wool lump containing 1 to 50% by weight of a binder fiber having a softening point at least 20 ° C. lower than the melting point of the latently crimpable fiber, and having an apparent density of 10 A cotton wool nonwoven fabric for cushioning material, characterized by having a compression residual strain of up to 49 kg / m ³ and a repetitive compression set of 8% or less. 2. A latently crimpable fiber having a low crimp of 50 to 99% by weight and a binder fiber having a softening point at least 20 ° C. lower than the melting point of the latently crimpable fiber having a low crimp. %, And the ball-shaped ingot is subjected to a heat treatment through the following production process A to cause the latently-crimpable fiber having low crimp to exhibit a high degree of crimp. A method for producing a cotton wool nonwoven fabric for cushioning material, wherein the molded nonwoven fabric is taken out after cooling to a temperature lower than the softening point of the binder fiber while holding the binder fiber. Step A: The binder fiber is softened, and after heating the cotton wool lump to a temperature at which a high degree of crimp is developed in the latently crimpable fiber having low crimp, compression molding is performed at a temperature equal to or higher than the softening point of the binder fiber. Or, after compression molding a ball-shaped mass at a temperature lower than the softening point of the binder fiber, the binder fiber softens while maintaining the compressed state, and a high degree of crimp is generated in the fiber crimpable fiber having low crimp. Heating to the temperature at which it develops. 3. A heated belt-shaped mass is compression-molded by a movable belt type holding device having a cooling function disposed immediately after a heat treatment machine, and the binder fiber is continuously softened while maintaining a compressed state. The method for producing a nonwoven fabric for a cushioning material according to claim 2, wherein the nonwoven fabric is cooled to a temperature of not more than a point.