JPS5936713B2 - Method for manufacturing a leather-like sheet with excellent dimensional stability - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing a leather-like sheet with excellent flexibility and dimensional stability.

In recent years, artificial leather has rapidly expanded its application fields.

Conventionally, it has been limited to general chair covers, bags, etc., but it is now widely used for general clothing.

At the same time, flexibility began to be required.

Moreover, it is required to be strong enough for use in clothing.

A typical means for softening is a method using recycled fibers such as a so-called polymer array invented by some of the present inventors.

Although these measures made the material more flexible, it was not sufficient to improve its physical properties, especially its dimensional stability.

Although various confectionery making methods other than the means of modifying fibers have been studied, it has not yet been possible to obtain a flexible leather-like sheet 1 with high dimensional stability.

In view of this situation, the inventors of the present invention have arrived at the present invention as a result of intensive studies in order to create a sheet that is highly flexible and has high dimensional stability.

That is, the present invention has the following configuration.

In a method of manufacturing a flexible sheet by adding a viscoelastic substance to a sheet containing repaperable fibers, a temporary filling substance or a mixture of a viscoelastic substance and a temporary filling substance is added to the sheet containing repaperable fibers. (1) thinning the repaperable fibers, (2) rearranging or additionally applying a low filler or a mixture of a temporary filler and a viscoelastic substance, (2) drying and fixing the sheet under tension in the width direction; This invention relates to a method for producing a leather-like sheet with excellent dimensional stability by (1) applying a viscoelastic substance and (2) removing a temporary filling substance.

This will be explained in more detail below.

The constituent fibers of the highly dimensionally stable sheet according to the present invention include at least recyclable fibers.

Recycleable fibers refer to fibers that can be divided and finely divided chemically, mechanically, thermally, or by a combination thereof.

Typical examples thereof are polymer arrays as typified by Japanese Patent Publication No. 46-27775, and furthermore, blend fibers, and fibers that can be made into multiple fibers by physical, chemical, thermal, or a combination of these methods. It is a type of fiber that can be split.

Next, the term "sheet" in the present invention refers to knitted fabrics, woven fabrics, nonwoven fabrics, and also those to which various binders and the like are attached.

These sheets may contain recyclable fibers as a constituent component.

The proportion of recyclable fibers does not necessarily have to be all of the fibers that make up the sheet; for example, in the case of knitting, weaving, etc., it is better to have recyclable fibers as a percentage of the vertical and horizontal composition. There are some things.

These, TL, etc. may be appropriately selected depending on the knitting/weaving structure, the density of the nonwoven fabric, and other conditions.

In particular, when making a sheet with naps by raising it, it is important to use recyclable fibers as the fibers that will form the naps.
This is an effective method in terms of cost and physical properties.

A temporary filler or a mixture of the temporary filler and a viscoelastic material is applied to such a sheet.

The temporary filling material in the present invention may be any material that is solid at room temperature when applied to the same sheet as the viscoelastic material and dried, and can be selectively dissolved and removed while leaving the viscoelastic material.
For example, (a) water, (b) alcohols with 15 or less carbon atoms, (C) esters with 15 or less carbon atoms, (d) ethers with 15 or less carbon atoms, (e) 15 carbon atoms or less. The following amines, (f) amides having 15 or less carbon atoms, (g
) Acetic acid or chlorinated acetic acid, (h) Chlorinated hydrocarbon having 10 or less carbon atoms, (i) Carboxylic acids having 15 or less carbon atoms, (
j) Substances that can be dissolved and removed by a liquid group consisting of ketones having carbon numbers of 15 or less and mixed liquids thereof are preferably used.

Specific examples include cellulose-based substances such as methylcellulose, polyvinyl acetate, polyvinyl alcohol, and copolymers thereof.

Further, inorganic salts such as calcium carbonate are also mentioned as an example.

These temporary fillers are usually applied to the sheet in the form of a solution or dispersion by a general impregnation method, spraying, coating, or the like.

The amount applied varies depending on the type of sheet, density, etc., and cannot be generalized, but it is approximately 1.0% by weight based on the fibers that make up the sheet.
It is preferable to apply 5 to 80% in terms of product texture, physical properties, etc.

On the other hand, when applying a mixture of a temporary filling substance and a viscoelastic substance, a solution, a dispersion, or a mixture of both may be used.
Further, the medium may be water or an organic solvent.

However, it is preferable that the mixing state of both be uniform.

The viscoelastic substances mentioned in the present invention refer to various viscoelastic substances that can be used for synthetic leather, including various polyurethanes, various rubber substances such as NBR, various polyacrylic esters, silicone rubbers, and fluoro rubbers. .

Usually a polymeric material with an elongation at break of 300% or more, 100%
A material with a stress of 200 Kp/d or less at % elongation is used (for the above measurements, the sample is a film (maximum thickness 2 m 7 IL), and there are no internal structural defects such as stress concentration that impair the original physical properties. Use one that has no grains and is not oriented in a specific direction.

The measurement method was to measure the sample at 20°C ± 2°C and RH 65% ± 2%.
Cut out a mm width and make the sample length 2CrrL, l Q e
(pulled at a speed of ra/ynin).

These viscoelastic substances may be used not only alone but in combination of two or more types.

The mixing ratio of the temporary filling material and the viscoelastic material is not particularly limited, but if the temporary filling material is small, the softness will be insufficient.

For this reason, 5 sections or more, more preferably 20 sections or more,
It is preferable to contain a temporary filler.

The amount of these mixtures applied to the sheet varies widely depending on the type of sheet, but it is desirable to apply the viscoelastic substance in an amount of 0.5% or more based on the fibers constituting the sheet.

If it is less than this, there is no advantage of adding a viscoelastic substance.

In particular, when using a large amount of fibers that are thinned by removing one or more components by chemical treatment etc. as the fibers constituting the sheet, it is preferable to add a large amount, and it is preferable to add 1% or more.

In addition, it is usually desirable to set it to 60% or less in consideration of the texture and other factors.

The application method may be the same as that for provision of the temporary filling, and various means such as impregnation, spraying, and coating can be employed.

After this, the temporary filling or the mixture of the viscoelastic substance and the temporary filling is fixed to the sheet by ordinary drying or wet coagulation.

Note that the fibers may become thinner in this step, that is, in the step of applying the temporary filler or the temporary filler and the viscoelastic material.

The fibers constituting the sheet are then thinned.

The reason why the sheet is thinned after the provision of the temporary filling is to reduce the volume due to thinning and to prevent the sheet from becoming excessively stretchable and causing poor workability.

A typical thinning method in the present invention is a method of dissolving and removing sea components of fibers having a so-called sea or island structure, and is very effective in softening the texture.

Furthermore, in the case of composite fibers made of two or more polymer components that differ in their swelling properties against liquids such as water or heat, it is also effective to use the difference in swelling to peel and thin the fibers.

The fineness after fineness is preferably 0.8 denier or less, particularly preferably 0.3 denier or less, considering the texture.

A temporary filling material is applied to the thinned sheet in this way, or a previously applied temporary filling material is rearranged.

In the case of reapplying the temporary filling, the same material as before may be applied, or a different type of temporary filling may be applied.

To rearrange the temporary filling, remove the sheet from the temporary filling's solvent or
This can be carried out by passing it through a dispersion medium, squeezing it with a mangle or applying vibration while passing it through, spraying or coating with a solvent or dispersion medium, or a combination thereof.

Rearrangement refers to changing the relative position of the temporary filler to the viscoelastic material and fibers within the sheet.

The reason why the phenomenon changes and the flexibility increases due to rearrangement is not clear, but because rearrangement causes part of the temporary filling to move and cover at least a part of the surface of the thinned fiber, It is presumed that this prevents adhesion between the viscoelastic substance and the fibers.

Further, when a temporary filling material is additionally applied here, a mixture of the temporary filling material and a viscoelastic material may be used.

In particular, when flexibility is required, it is desirable to add at least 3 inches of temporary filler to the fiber weight in this step.

What is required here is that the temporary filling material is plasticized by additional application or rearrangement, and the sheet is made flexible.

This softening makes it possible for the first time to uniformly perform the process of suppressing width shrinkage or expansion process of the sheet.

At the same time as this step or after this step, the sheet is dried and fixed while being taut in the width direction.

In particular, it is desirable not only to suppress shrinkage in the width direction, but also to
It would be desirable to expand the width further.

In systems where the sheet swells when temporary filling is reapplied or rearranged, it is essential to expand in the width direction.

- For sheets that shrink significantly when force or temporary filling is reapplied, simply suppressing the shrinkage can have a great effect.

The rate of expansion depends in part on the type of sheet and the swelling (stretching) rate at the time of reapplying, but it is particularly desirable that the sheet expands by 1% or more compared to the case without tension.

Further, the maximum expansion rate is 90%.

If it is more than this, the vertical and horizontal balance will be lost and the sheet will expand unevenly, which is undesirable.

Particularly desirable is 2 to 20%.

This expansion is effective not only in the width direction but also in the length direction.

These operations can be performed using a conventional pin tenter, clip tenter, etc.

It may be expanded only in one direction, expanded only in the width direction while suppressing shrinkage in the length direction, or expanded biaxially in both the width direction and the length direction.

Further, this operation does not need to be performed only once, and may be performed several times.

In other words, it is an effective method to expand the temporary filling once in the width direction when reapplying it, and then expand it further.

After this, a viscoelastic substance is applied.

The viscoelastic material may be one that has been applied before, or it may be something else.

The viscoelastic material may be a dispersion type or a solution type.

The applied amount may be in the same range as mentioned above, and the total applied amount of the viscoelastic substance is selected from the range of 1 to 120% based on the weight of the fiber.

When the viscoelastic material is of an emulsion type and requires heat setting, it may be appropriately heat set.

In addition, if it is a wet coagulation type, it coagulates sufficiently.

After that, the temporary filling is removed.

The removal method can be carried out by a conventional method.

The following will be described in more detail with reference to Examples.

How to measure strength The measurement method in the present invention was as follows.

At 20°C ± 2°C and RH 65% ± 2%, a sample was cut out to a width of 5 mm, and the sample length was 10 crrL, l Q cm /m.
Pull at a speed of in.

Strength is the quotient of the maximum stress during a tensile test divided by the strength of the sample.

Moreover, the elongation was defined as the elongation at the time of maximum stress during the tensile test.

Flexibility measurement method: Measured using the cantilever test method in JIS L 1079 Chemical Fiber Fabric Test Method.

Example 1 The island component is nylon 6, the sea component is polystyrene with 20 molar coelectrode of 2-ethylhexyl acrylate,
The ratio of island to sea is 50:50 by weight, and the fineness is 4.
．． A polymeric mutual array of Sa (36 islands) was used to form a web, which was then needle punched to form a nonwoven fabric.

This was followed by a hot water treatment at 80°C. At this time, the area decreased by 31%.

This felt was impregnated with a 9% aqueous solution of polyvinyl alcohol.

The amount applied was 17% to the fiber.

After that, the sea component was removed using Triclean to thin the fibers.

The removal rate of sea components was 98.6%.

Thereafter, the thinned sheet was passed through a 3% PVA aqueous solution bath, and was twisted twice with a mangle to reapply the temporary filling.

In this step, PVA increased by 1.3% compared to before treatment.

Thereafter, it was expanded by 5% in the width direction using a clip tenter.

It was dried at 100° C. until the weight became constant while it was expanded in the width direction.

As a result, the width was expanded by 4.8%.

On the other hand, compared to the felt after thinning, the length direction was also expanded by two folds.

Thereafter, a 14% polyurethane solution (solvent dimethylformamide) was applied, wet coagulation was performed, and polyvinyl alcohol was removed by passing it through a mangle with 85° C. hot water 15 times.

The amount of polyurethane applied was 37 inches per fiber.

Slice this sheet into two pieces, buff with sandpaper,
It was made into a brushed sheet and further dyed to make artificial leather.

The resulting product has an excellent flexibility of 45 mm in the vertical direction and 32 mm in the horizontal direction, and has a beautiful nap.The product has a thickness of 0.6 mm, a longitudinal strength of 10.2 Kp, a Z virtue, and an elongation of 110%. It had excellent dimensional stability, with a widthwise strength of 6.6 Kp/cm and an elongation of 140%.

Comparative Example 1 The felt of Example 1 was cut after the fibers had been thinned, and the cut felt was passed through a 3% PVA aqueous solution bath, and twice squeezed with a mangle to reapply the temporary filling material.

In this step, PVA increased by 8% compared to before treatment.

Thereafter, using a clip tenter, it was dried at 100° C. until the weight became constant while shrinking by 0.3% in the width direction.

As a result, the width direction was shrunk by 0.3%.

On the other hand, in the length direction, compared to the felt after thinning, 3.
Expanded by 1%.

Thereafter, a 14% polyurethane solution (solvent dimethylformamide) was applied, wet coagulation was performed, and 15%
Polyvinyl alcohol was removed by passing it through a mangle.

The amount of polyurethane applied was 40% based on the fiber.

Slice this sheet into two pieces, buff with sandpaper,
It was made into a raised sheet and further dyed.

The obtained product has an excellent thickness of 0.6 mm, flexibility of 46 mm in the vertical direction and 327 XIX in the horizontal direction, and a strength of 9 Kp/C in the longitudinal direction.
TL, elongation 110%, strength in width direction5. The dimensional stability was poor with IKp/cm and elongation of 175%.

Example 2 The island component is nylon 6, the sea component is polystyrene with 18 molar coelectrode of 2-ethylhexyl acrylate,
A web was made using a polymer array (16 islands) with an island/sea ratio of 40/60 (weight ratio) and a fineness of 5.5 d, and was needle-bunched to obtain a nonwoven fabric.

Thereafter, it was treated with hot water at 80°C. At this time, the area is 29.5
% decreased.

The felt weight was 503 El/m'.

Next, add 7% polyvinyl alcohol (PVA) to the felt.
, and a mixture of emulsion polyurethane No. 7 was impregnated.

The total amount of PVA and polyurethane applied was 17% to the fiber.

Next, the sea component was removed using Triclean to thin the fibers.

The removal rate was 98.6%. Next, it was heat set at 150°C for 10 minutes, and then passed through water at 60°C for about 1 minute, and then passed through a mangle twice to rearrange the PVA.

Thereafter, it was expanded by 6% in the width direction using a clip tenter.

It was dried at 100° C. until the weight became constant while it was expanded in the width direction.

As a result, the width was expanded by 5.7%.

On the other hand, compared to the felt after thinning in the length direction, it is 1.5
%expanded.

Thereafter, a DMF solution of polyurethane with a concentration of 10.5% was applied, wet coagulation was performed, and PVA was removed by passing through a mangle with 85° C. hot water 15 times.

The total amount of applied polyurethane (total of emulsion and solution polyurethane) was 38.8% to the fiber.
Met.

This sheet was buffed with sandpaper to create a raised sheet, and then dyed to create artificial leather.

The obtained product has a thickness of Q, 55 mm, and a flexibility of 49 mm.
It has an excellent width of 37 mm, and has a dense and beautiful nap, with a longitudinal strength of 13.2 kg/cTL, and an elongation of 71%.
It had extremely high dimensional stability, with a widthwise strength of 8.2 KVcm and an elongation of 120%.

Examples 3 and 4, Comparative Example 2 Polymer array (36 items, islands/sea = 40/60 islands =
Nylon-6, sea = polystyrene, 3dX51iyx)
The fibers are passed through a card to form a web, and then 300
0 and 7 needle punched and made into felt.

Thereafter, it was passed through hot water at 60°C and 80°C to shrink.

The area shrinkage rate was 30%. The weight of the felt after shrinkage was 45,097 m2.

Furthermore, the felt was impregnated with a mixed solution of 7% polyvinyl alcohol and 5% emulsion polyurethane (remaining 85% water).

After that, it was poured into Triclean and squeezed with a mangle to remove the sea components.

The removal rate of sea components was 97.5%. After that, 5%P
Passing into VA aqueous solution a: Comparative Example 2) Scooped twice with a mangle.

(b: Example 3) After passing through the mangle once, the width was increased by 5% (relative to the sea-free felt) and the material was passed through the mangle once more.

(c: Example 4) After passing through the mangle once, widen the width by 5%, and after passing through the mangle once, further widen the width,
The width was expanded so that the total width including the width expansion was 10%.

After that, (a), (b). (c) was dried at 100°C.

As a result, (a) is 5% in the length direction compared to before this treatment.
．． It had elongated by 2% and shrunk by 1.2% in the width direction.

(b) had elongated by 3.6% in the length direction and by 4.8% in the width direction.

(c) stretches 2.7% in the length direction and 8.9% in the width direction
It was growing.

Furthermore, heat setting was performed at 150° C. for 5 minutes.

After this, 12% DMF solution polyurethane was impregnated, poured into water, solidified, and PVA removed in hot water.
I did this.

The amount of polyurethane applied was 37.8 parts based on the fiber.

Thereafter, buffing and dyeing were performed to obtain a suede-like fabric with a good nap and soft texture.

The physical properties are as shown below, and when stretched in the width direction, the vertical and horizontal balance can be achieved.

However, the texture is not that hard.

Comparative Examples 3, 4, 5 The shrink felt of 1 above was impregnated with a 12% aqueous solution of polyvinyl alcohol.

After that, it was poured into a trichloride and squeezed with a mangle to remove the sea components.

The removal rate of sea components was 97.8%.

After this, the DMF solution polyurethane concentration was adjusted, and the sea-removed felt was impregnated, coagulated in water, and PVA-removed in hot water.

As a result, the amount of polyurethane applied to the fiber (d: Comparative Example 3
) 45.0 parts, (e: Comparative Example 4) 50.3 parts, and (f: Comparative Example 5) 54.1 parts.

After that, it was puffed and dyed.

(d) was a suede-like fabric with a relatively good nap, but (e) and (f) had short naps and an extremely hard feel.

As for the physical properties, as shown below, it was not possible to achieve both flexibility and dimensional stability even if the amount of polyurethane applied was changed.

Claims (1)

[Claims] 1. A step of applying a temporary filling substance or a mixture of a temporary filling substance and a viscoelastic substance to a sheet containing repaperable fibers, ■ A process of thinning the repaperable fibers, and ■ Adding a temporary filling substance or a mixture of a temporary filling substance and a viscoelastic substance. Dimensional stabilization consisting of the steps of rearranging or additionally applying a mixture of elastic substances, ■ drying and fixing the sheet under tension in the width direction, ■ applying a viscoelastic substance, and ■ removing the temporary filling material. A method for producing a leather-like sheet with excellent properties.