JP2003147688A - Leather-like sheet base body and method for producing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a leather-like base body excellent in melt resistance, flame retardance, dyeability, having sufficient strengths and soft and novel hand feeling. SOLUTION: In the leather-like sheet base body comprising a nonwoven fabric in which micro fibers (A) are three dimensionally interlaced and an elastic polymer (B), 30-90 wt.% of the micro fibers (A) comprises an ethylene- vinyl alcohol-based copolymer containing 25-70 mole% ethylene and 10-70 wt.% of the same comprises a nylon, while 100 pts.wt. of the elastic polymer (B) includes 10-200 pts.wt. aluminum oxide.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a leather-like sheet having excellent softness and stain resistance of tobacco, having flame retardant performance (retardation) conforming to JIS D1201 standard, and having a new soft texture. It is a thing.

[0002]

2. Description of the Related Art Conventionally, as fibers constituting a leather-like sheet, polyester type and nylon type have excellent dyeability,
Although it is widely used because it has mechanical properties, these leather-like sheets have the drawbacks that mud and dust are likely to adhere to them and that they are inferior in resistance to heat such as frictional heat and cigarettes. Further, a leather-like sheet made of polyester fibers has a drawback that the texture is harder than that made of nylon fibers due to the physical properties of the fibers, and a leather-like sheet having a soft texture is required. On the other hand, some of the inventors of the present invention have disclosed a leather-like sheet made of an ethylene-vinyl alcohol-based copolymer to JP-A 2000-0.
It is proposed in Japanese Patent No. 17580.

[0003]

Although such a leather-like sheet had a soft texture, ethylene-
Since the vinyl alcohol-based copolymer itself has a low resistance to moisture and heat before the acetalization treatment step, the fibers stick together during the hot water treatment to increase the fluff density on the sheet surface, the subsequent drying step, the drying step after dyeing, etc. There was something to do. Further, a leather-like sheet having higher strength physical properties and excellent dyeability is desired. Further, depending on the use of the artificial leather, not only the texture and the strength physical properties required for the artificial leather as a substitute for the natural leather, but also the addition of a special function is desired. For example, in the field of interiors, particularly in the field of artificial leather used for upholstery materials such as seats for railroad cars, seats for automobiles, and seats for aircraft, it is extremely important to impart flame retardancy.

An object of the present invention is to solve the above-mentioned problems, that is, it is excellent in anti-fusing property and flame retardancy, further excellent in dyeability, and has a soft texture, and in addition, it is excellent. Another object is to provide a leather-like sheet having excellent strength.

[0005]

That is, according to the present invention,
In a leather-like sheet substrate composed of a non-woven fabric in which ultrafine fibers (A) having a size of 5 decitex or less are three-dimensionally entangled and a polymer elastic body (B), 30 to 90% by weight of the ultrafine fibers (A)
Ethylene having an ethylene content of 25 to 70 mol%
Made of vinyl alcohol-based copolymer, and 10 to 70
A leather-like sheet substrate, characterized in that the polymer elastic body (B) contains 10 to 200 parts by weight of aluminum hydroxide based on 100 parts by weight of the polymer elastic body (B). Is. Further, the present invention provides a leather-like sheet substrate comprising a nonwoven fabric in which ultrafine fibers (A) having a size of 0.5 decitex or less are three-dimensionally entangled and a polymer elastic body (B). A step of producing an entangled nonwoven fabric composed of ultrafine fiber-generating fibers in which two components of fibers are an ethylene-vinyl alcohol copolymer and nylon, and a polymer elastic body containing aluminum hydroxide in the entangled nonwoven fabric (B And a step of converting the ultrafine fiber-generating fibers into a bundle of ultrafine fibers of 0.5 dtex or less, in the order of or. . In this manufacturing method, a bundle of ultrafine fibers having a single fiber fineness of 0.5 decitex or less is prepared by a conventionally known method. For example, an ultrafine fiber-generating fiber composed of at least two types of incompatible polymers, at least one type of polymer having an island component in the cross section, and at least one other type of polymer having a sea component in a cross section, a so-called sea-island type fiber By laminating or decomposing and removing at least one component (usually a sea component polymer) from or from a laminating type ultrafine fiber-generating fiber having a cross-sectional shape in which two or more incompatible polymers are joined It can be obtained by peeling at the interface. It should be noted that the above steps (1) to (4) are only the steps essential to the production of the leather-like sheet substrate of the present invention, and steps other than these may be added.

The ethylene-vinyl alcohol copolymer used in the present invention is a saponified product of an ethylene vinyl acetate copolymer. The amount of ethylene contained in the copolymer is 25
˜70 mol%, preferably 30 to 50 mol%. When the ethylene content of the copolymer is less than 25 mol%, the heat resistance is reduced, and when the copolymer is made into fibers, the copolymer gels, and the spinnability and stretchability are reduced. Further, when the ethylene content of the copolymer exceeds 70 mol%, not only the hydroxyl group becomes small and the desired texture cannot be obtained, but also sufficient melting prevention is obtained when the acetal decomposition regeneration treatment described below is performed. Property and flame retardant performance cannot be obtained.

The ethylene-vinyl alcohol copolymer can be obtained by saponifying a copolymer of ethylene and vinyl acetate with sodium hydroxide, and the saponification degree is preferably 95% or more. If the degree of saponification is too low, the heat resistance will decrease, and the copolymer will gel when fibrous,
Not only the spinnability and the drawability are lowered, but the crystallinity of the copolymer is lowered and the fiber properties such as strength are lowered, and the copolymer is apt to be softened to cause a trouble in the processing step. The texture of the obtained leather-like sheet may be deteriorated as it comes up.

The ethylene-vinyl alcohol copolymer according to the present invention can be produced by a known method. For example, ethylene and vinyl acetate are radically polymerized in the presence of a radical polymerization catalyst in a polymerization solvent such as methanol, and then unreacted monomers are expelled to cause a saponification reaction with sodium hydroxide to produce an ethylene-vinyl alcohol copolymer. After that, it is pelletized in water, washed with water and dried. Alkali metals and alkaline earth metals are likely to remain in the copolymer in the process, and the presence of these metal ions facilitates thermal decomposition of the copolymer, and therefore the pellets are further washed with pure water containing acetic acid. It is preferable to wash with pure water only.

By adding a specific amount of acid and / or its metal salt to the ethylene-vinyl alcohol copolymer, the gelation-preventing effect at the time of melt molding becomes more sufficient. As the acid, various inorganic acids and organic acids can be used and are not particularly limited, and specifically, phosphoric acid, phosphorous acid, acetic acid, oxalic acid, succinic acid, adipic acid, tartaric acid, citric acid, etc. Examples include acids. Further, it is more preferable that this acid has a boiling point of 115 ° C. or higher because it can prevent the acid and the like from volatilizing when the chip is dried after the treatment. The metal salt of these acids is not particularly limited, and examples thereof include sodium salt, potassium salt, lithium salt, magnesium salt, calcium salt, barium salt and the like, and sodium acetate, potassium acetate, calcium acetate and the like. Can be used. When a polybasic acid is used, its metal salt may be a partial salt, and sodium dihydrogen phosphate, potassium dihydrogen phosphate, etc. can also be used. The leather-like sheet substrate made of the ethylene-vinyl alcohol-based copolymer of the present invention can be dyed with a slene dye, but has a unit having a sulfonic acid group or a sulfonate group in the main chain of the ethylene-vinyl alcohol-based copolymer. Copolymerization also enables dyeing with a cationic dye. The copolymerization amount is from 0.05 to 1.
It is preferably 0 mol% copolymerized, and more preferably 0.1 to 0.7 mol%. Copolymerization amount is 0.0
When it is less than 5 mol%, it is difficult to obtain sufficient color developability when dyeing with cation. The copolymerization amount is 1.0 mol%
When it exceeds the above range, the melting point of the copolymer is remarkably lowered, and the copolymer is apt to be fused during drying, or a gelled product is liable to be generated in the fiberizing step, resulting in poor spinnability.

If necessary, 0.1 to 5 wt% of fine particles having an average particle size of 100 μm or less can be added to the ethylene-vinyl alcohol copolymer at the time of polymerization or thereafter. The material of the fine particles is not particularly limited, and examples thereof include silica gel (colloidal silica), dry process silica,
Dry process silica containing aluminum oxide, dry process silica having an alkyl group on the particle surface and blocking silanol groups on the particle surface, alumina sol (colloidal alumina), fine particle alumina, fine particle titanium oxide, calcium carbonate sol (colloidal carbon dioxide) Preferable examples include inert fine particles such as calcium) and internally precipitated fine particles in which a phosphorus compound and a metal compound are precipitated. In particular, silica fine particles having an average particle diameter of 15 to 70 μm are preferable, and spinnability and stretchability are improved, and unevenness is obtained on the fiber surface, resulting in deep color in the leather-like sheet after dyeing and improved sharpness. To be done.

The nylon used in the present invention is not particularly limited, and aliphatic nylon or semi-aromatic nylon such as 6 nylon, 10 nylon, 12 nylon, 6-6 nylon and 6-12 nylon can be used. 6-nylon is preferable because it can be stably spun at the spinning temperature of the ethylene-vinyl alcohol copolymer and is easily available.

In the present invention, the main component of the fiber component composed of the ethylene-vinyl alcohol copolymer and the main component of the fiber component composed of nylon must be 0.5 decitex or less. It is preferably 0.3 decitex or less, more preferably 0.1 decitex or less. If the main component of the ultrafine fibers exceeds 0.5 dtex, the appearance will be poor and the softness and touch will also be poor when a suede-like artificial leather is obtained.

In the present invention, the fiber comprising the ethylene-vinyl alcohol copolymer is 30% by weight to 90% by weight of the fiber component.
Must be% by weight. When the amount of the fibers composed of the ethylene-vinyl alcohol copolymer is less than 30% by weight of the fiber component, a leather-like sheet having excellent softening resistance and flame retardancy, which is the object of the present invention, and having a soft texture can be obtained. Absent. Further, when the fiber made of the ethylene-vinyl alcohol copolymer exceeds 90% by weight of the fiber component, a leather-like sheet excellent in strength and color developability after dyeing cannot be obtained. Nylon fibers should be 10% to 70% by weight of the fiber component. When the fiber made of nylon is less than 10% by weight of the fiber component, the strength and color developability of the obtained leather-like sheet are not sufficient. Further, if the fiber made of nylon exceeds 70% by weight of the fiber component, the leather-like sheet excellent in anti-fusing property and flame retardant performance, which is the object of the present invention, cannot be obtained.

The sea-island structure fiber used in the present invention is a combination of the ethylene-vinyl alcohol copolymer obtained as described above, nylon and one or more thermoplastic polymers having low compatibility with these resins. It is obtained by spinning. The ultrafine fibers used in the present invention are most preferably a combination of ethylene-vinyl alcohol copolymer and nylon, and when polyester fibers are used instead of nylon, leather obtained from the properties of polyester fibers The texture of the sheet base is hard,
The ethylene-vinyl alcohol copolymer is less likely to be dyed with a disperse dye, and the spinnability of both fibers will be a problem.

The sea component polymer is ethylene-based under spinning conditions.
A polymer having a smaller melt viscosity and a larger surface tension than those of the vinyl alcohol copolymer and nylon is preferable. In addition, the solubility or decomposability of the ethylene-vinyl alcohol copolymer and nylon with respect to the solvent or the decomposing agent must be different (greater than the ethylene-vinyl alcohol copolymer and nylon). I won't. Further, it is a polymer having a low compatibility with the ethylene-vinyl alcohol copolymer and nylon. For example, it is at least one polymer selected from polymers such as polyethylene, polystyrene, copolymerized polyethylene, modified polyester, and thermoplastic polyvinyl alcohol. For example, polyethylene can be easily extracted with toluene, polystyrene can be easily extracted with trichlene, modified polyesters such as sodium sulfoisophthalate copolymerized polyethylene terephthalate can be decomposed with alkali, and thermoplastic polyvinyl alcohol can be decomposed and removed with hot water. Then, by extracting or decomposing and removing the sea component polymer from the sea-island structure fiber, the fiber fineness is reduced to 0.
An ultrafine fiber bundle having 5 decitex or less can be formed.

In the present invention, the sea-island structured fiber means that the sea component may be divided into a plurality of parts by the island component polymer in the cross section of the fiber. For example, the sea component polymer and the island component polymer are each a layer, It may be a fiber in a laminated state or a fiber in which the island component has a core-sheath structure. The island component polymer may be endlessly continuous in the fiber length direction or may be discontinuous.

The sea-island fiber structure most preferably used in the present invention is such that the island component is an ethylene-vinyl alcohol copolymer, the sea component is a mixture of nylon and polyethylene, and nylon is the island component among the sea components. , Polyethylene is a sea component. The leather-like sheet made of a conventional ethylene-vinyl alcohol-based copolymer has a problem that the heat resistance of the ethylene-vinyl alcohol-based copolymer itself is low before the acetalization treatment step, so that the fibers are stuck to each other in a wet heat state. However, when the fiber component is arranged in this way, the fibers of the ethylene-vinyl alcohol copolymer do not stick to each other because nylon is interposed between the fibers of the ethylene-vinyl alcohol copolymer. Therefore, when polyethylene, which is a sea component among sea components, is extracted with toluene and washed with hot water, ethylene-
Since the island component of the vinyl alcohol copolymer is surrounded by the island component of nylon, it is possible to prevent the island components of the ethylene-vinyl alcohol copolymer from shrinking and sticking together during the hot water washing treatment. Not at the time of hot water treatment to increase the fluff density of the sheet surface, the subsequent drying step,
It is possible to solve the problem that the fibers stick to each other in the drying step after dyeing and the strength properties or the appearance and texture are deteriorated.
Since the fiber physical properties of nylon are softer than the fiber physical properties of polyester, the soft texture of the leather-like sheet substrate of the present invention can be obtained. In the present invention,
It is possible to add a polymer other than nylon and an ethylene-vinyl alcohol copolymer as a part of the island component polymer as long as the effect of the present invention is not impaired.

Fibers in which an ethylene-vinyl alcohol copolymer and nylon are alternately laminated in a multi-layered state can also be obtained as ultrafine fibers of 0.5 decitex or less after division, and the ethylene-vinyl alcohol copolymer is obtained. These fibers are preferred because they do not easily stick together.

The spun raw yarn is subjected to drawing after being once wound or without being wound, and the drawing is performed by hot drawing. Usually, it is stretched in a water bath at a temperature of about 50 to 100 ° C. at a stretch ratio of 0.55 times or more, preferably 0.70 times or more higher than the cutting and stretching ratio. The draw ratio is 0.5 of the cutting draw ratio.
If it is less than 5 times, artificial leather having sufficient strength cannot be obtained.

The drawn ultrafine fiber-generating type sea-island structure fiber is once wound or crimped without being wound, and further defibrated with a card to form a web through a webber, and then a known method, For example, a non-woven fabric is obtained by performing an entanglement treatment by a needle punching method or a high-pressure water entanglement treatment method, or a web made of this staple is laminated on a knitted fabric, and a means such as a high-pressure water stream treatment or a needle punching treatment Are entangled with each other to obtain a laminated nonwoven fabric.

If necessary, a polyvinyl alcohol-based sizing agent is applied to the non-woven fabric produced by the above-mentioned method, or the surfaces of the constituent fibers are melted to bond the constituent fibers of the non-woven fabric, and the non-woven fabric is temporarily prepared. You may perform the process which fixes. By performing this treatment, it is possible to prevent structural destruction of the nonwoven fabric due to tension or the like in the subsequent step of impregnating with the elastic polymer solution.

A nonwoven fabric made of an ethylene-vinyl alcohol copolymer and nylon receives heat to shrink the fibers, so that the fluff density is increased and the appearance is improved. The shrinking method may be a method of putting it in hot air or a method of putting it in hot water, but the degree of shrinkage is preferably 20% or more in area. The thickness of this entangled nonwoven fabric is 0.5 to 4.0 mm.
Is preferable from the viewpoint of ensuring process passability, and the apparent specific gravity is 0.25 to 0. from the viewpoint of controlling the ratio of the fiber to the elastic polymer when the elastic polymer is applied in the next step.
50 g / cm ³ is preferred. If it is less than 0.25 g / cm ³ , the obtained sheet becomes rubber-like, and 0.50 g / cm ³
If it exceeds, the elastic polymer is not sufficiently applied, and a leather-like texture cannot be obtained.

Next, the entangled nonwoven fabric is impregnated with an elastic polymer liquid and gelled by heating and drying, or it is immersed in a liquid containing a non-solvent of the elastic polymer to wet-coagulate it to form an elastic polymer. Form a dense foam sponge. The elastic polymer impregnated here has, for example, an average molecular weight of 500.
Of at least one polymer diol selected from diols such as polyester diols, polyether diols, polycarbonate diols and the like, or composite diols such as polyester polyether diols, and the like;
At least one selected from aromatic, alicyclic, and aliphatic diisocyanates represented by 4,4′-diphenylmethane diisocyanate, isophorone diisocyanate, hexamethylene diisocyanate, and the like.
Examples include polyurethanes obtained by reacting two types of diisocyanates with at least one type of low molecular weight compound having two or more active hydrogen atoms represented by ethylene glycol, isophorone diamine, etc., and a modified product thereof. Other examples include polyester elastomers, elastic polymers such as hydrogenated products of styrene-isoprene block copolymers, and acrylic resins.
A polymer composition obtained by mixing these may also be used. But,
The above-mentioned polyurethane is preferably used because of its flexibility, elastic recovery property, sponge-forming property and durability.

The cloth is impregnated with a polymer solution obtained by dissolving or dispersing the above-mentioned polymer in a solvent or a dispersant, and treated with a non-solvent of resin to wet-coagulate to form a sponge, or heat-dried as it is. Then, a leather-like sheet is obtained by gelling and forming a sponge. Additives such as a colorant, a coagulation regulator, an antioxidant, and a dispersant may be added to the polymer liquid, if necessary. Particularly, in the present invention, for the purpose of imparting flame-retardant performance to the leather-like sheet and further improving the anti-fusing property, 10 to 200 parts by weight of aluminum hydroxide is added to 100 parts by weight of the polymer elastic body. To do. Aluminum hydroxide, a flame retardant, is 10
If it is less than 100 parts by weight, flame retardancy and sufficiently satisfactory anti-fusing property cannot be obtained when it is used as a leather-like sheet substrate, and if it exceeds 200 parts by weight, it is difficult for the polymer elastic body to sufficiently retain aluminum hydroxide. And the texture becomes hard and a good substrate cannot be obtained. In consideration of dispersion stability in the impregnation liquid and flame retardant effect, the average particle size is 2 μm or less, especially 1 μm.
The following aluminum hydroxide fine particles are preferable. The aluminum hydroxide particles may be subjected to various treatments for improving performance such as moisture resistance, heat resistance, water resistance, and acid resistance, if necessary. Then, not only imparting flame retardancy by adding aluminum hydroxide, but also ethylene-
Due to the mutual effect of the fusion resistance of the fibers of the vinyl alcohol-based copolymer and the flame retardance of aluminum hydroxide, the fusion resistance of the obtained leather-like sheet was sufficiently satisfied. The proportion of the polymer elastic material in the fiber sheet after the sea component is removed is 10% or more by weight as a solid content, preferably 3%.
It is in the range of 0 to 50%. When the elastic body ratio is less than 10%, a dense elastic body sponge is not formed, and the ultrafine fibers are likely to be loosened after the generation of the ultrafine fibers.

Next, in the present invention, the fiber sheet containing the elastic polymer is treated with a chemical agent which is a non-solvent for the island component polymer and the elastic polymer and a solvent or a decomposing agent for the sea component polymer. Generate fiber bundles. The ultrafine fibers formed by removing the sea component from the sea-island structure fibers must have a fineness of 0.5 decitex or less. It is preferably 0.3 decitex or less, more preferably 0.1 decitex or less. When the main component of the ultrafine fibers exceeds 0.5 decitex, the appearance becomes poor and the softness and touch are also deteriorated when the suede-like appearance is obtained.

In the leather-like sheet of the present invention, the fact that the fiber made of the ethylene-vinyl alcohol copolymer, which is one of the constituents, is acetalized improves the resistance to moist heat.
Not only is it preferable in that shrinkage is prevented from occurring in the manufacturing process and the sewing process, but it is also preferable in that it is possible to impart the anti-fusing property. A suitable acetalization method is pH 1.0.
Under acidic condition of ~ 5.0, general formula

[Chemical 1] (In the formula, R¹, R^Two, R^ThreeAnd R^FourIs an alkyl group
R is R¹And R^Two, R ^ThreeAnd R^FourAchille formed a ring
R group⁵Represents hydrogen or an alkyl group. Also
n is a number from 2 to 10. These R¹, R^Two, R^Three,
R^FourAnd R⁵The group may have a substituent. )so
In a solution containing at least one of the compounds shown,
After immersing in water or solution, the temperature is 80 ℃ or more and 160 ℃ or less
Is preferably treated with.

The compound is extremely stable because it is blocked at the end with an alkyl group or an alkylene group forming a ring, and is not oxidized even when contacted with oxygen such as air. Due to this end-blocking, the acetal decomposition reaction of the chemical substance itself proceeds by applying high temperature and high pressure even under weak acidity, and when an ethylene-vinyl alcohol-based copolymer having a hydroxyl group coexists therein, the side of the copolymer swollen with water Acetalization reaction occurs. By the decomposition regeneration reaction (cross-linking reaction) of acetal accompanied by dealcoholization, the wet heat resistance of the ethylene-vinyl alcohol copolymer is improved, and the shrinkage treatment step, hot water treatment step and drying step in the production of the leather-like sheet substrate, etc. In addition to improving the process passability in
It also improves the fusion resistance, dimensional stability, and steam iron resistance of leather-like sheets.

In the formula, the alkyl group represented by R ^{1 to} R ⁴ is preferably a lower alkyl group having 1 to 4 carbon atoms, and of these, a methyl group is preferred from the viewpoint of ease of use. The alkyl group may be substituted with an alkyleneoxy group such as an ethyleneoxy group, and R ^{1 to} R ⁴ may all be the same type of alkyl group or different. Further, as the alkylene group forming a ring, a lower alkylene group having 1 to 4 carbon atoms is preferable, but in consideration of the stability of the ring structure, a 5-membered ring, 6
A member ring is preferable, and therefore an ethylene group or a propylene group having 2 to 3 carbon atoms is preferable. These alkyl groups,
Any of the alkylene groups may have a substituent. Further, in the formula, n is a value calculated in view of the composition ratio when a plurality of compounds are treated, and is not limited to an integer.

Since the compound is sparingly soluble in water, when used as an aqueous solution, it is emulsified by using an anionic surfactant such as sodium dodecylbenzenesulfonate or sodium oxyalkylene-modified sulfonate of polycyclic phenol. It can be used in a state. Alternatively, a mixed solvent of water-alcohol can be used. The concentration of the compound is preferably 10 to 40% by weight, more preferably 15 to 30% by weight, based on the ethylene-vinyl alcohol copolymer to be treated.

As the acetalization adjusting agent, it is preferable to use an inorganic salt composed of a strong acid and a strong base, and sodium sulfide is preferably used from the viewpoint of versatility. When the pH of the treatment liquid is less than 1.0, the crosslinking of the resurface layer of the ethylene-vinyl alcohol-based copolymer takes precedence, which is not preferable in terms of the useful crosslinking degree, and causes problems of coloring and yellowing. Further, in the case of simultaneous dyeing described later, fading of the dyed product,
The problem of poor light fastness occurs. On the other hand, when the pH exceeds 5.0, the acetal decomposition regeneration reaction is difficult to proceed unless the conditions such as the treatment temperature and the treatment time are harsh, and the initial purpose is to have a good texture and to have a hot water resistance. It is difficult to obtain improved crosslinked fibers. From the viewpoint of preventing the deterioration of the dye and treating the acetal decomposition and regeneration reaction, the pH is preferably 2.0 or higher, and is preferably 4.0 or lower.

In order to obtain sufficient hot water resistance, the treatment temperature is 80 ° C or higher and 160 ° C or lower, especially 90 ° C or higher and 15 ° C.
It is desirable to set it to 0 ° C or lower. When the treatment is carried out in a solution, the treatment temperature is preferably 80 ° C or higher and lower than 140 ° C. When the temperature is lower than 80 ° C, the acetal decomposition / regeneration reaction rate becomes remarkably slow in the above-mentioned pH range, the crosslinking is insufficient, and stable texture, melting resistance, hot water resistance, and steam iron resistance are exhibited. Hateful. Especially the processing temperature is 100
If the temperature is lower than 0 ° C, excessive shrinkage is less likely to occur and the process is stable, but the reaction rate becomes slower, so it is preferable to use a known agent having a crosslinking promoting action, such as β-naphthalenesulfonic acid formaldehyde condensate. On the other hand, when the treatment temperature exceeds 140 ° C., the treated ethylene-vinyl alcohol-based copolymer causes excessive shrinkage and becomes hard, and the texture as a leather-like sheet is greatly impaired.
When the non-woven fabric is immersed in the solution, the non-woven fabric is impregnated with the cross-linking agent, and then the drying / cross-linking reaction is performed in a hot air oven, the treatment temperature is
The temperature is preferably 00 ° C or higher and lower than 160 ° C. When the temperature is lower than 100 ° C, the acetal decomposition / regeneration reaction rate is remarkably slowed in the above-mentioned pH range, the crosslinking is insufficient, and stable texture, melting resistance, hot water resistance, and steam iron resistance are exhibited. Hateful. On the other hand, when the treatment temperature exceeds 160 ° C., the treated ethylene-vinyl alcohol-based copolymer causes excessive shrinkage and becomes hard, and the texture as a leather-like sheet is greatly impaired. Also in this case, since the reaction rate becomes slow, it is preferable to use a known agent having a crosslinking promoting action, for example, β-naphthalenesulfonic acid formaldehyde condensate in combination. The acetal decomposition / regeneration reaction treatment can also be carried out simultaneously with the step of shrinking the nonwoven fabric to increase the fluff density of the leather-like sheet. For example 90
The nonwoven fabric may be dipped in a solution at a temperature of ℃, and the nonwoven fabric may be impregnated with a cross-linking agent at the same time as hot water shrinkage, and the acetalization reaction may proceed in the drying step.

The hot water resistance of the leather-like sheet substrate is further improved by subjecting the ethylene-vinyl alcohol copolymer to dry heat treatment at a temperature not higher than the melting point of the copolymer before the acetal decomposition / regeneration reaction treatment. In particular, it is preferable to perform dry heat treatment at a temperature in the range of (melting point-20) ° C to (melting point-5) ° C of the copolymer.

The leather-like sheet substrate of the present invention has a soft texture, a thickness of 0.4 mm or more, and a basis weight of 150 g.
/ M ² or more is preferable. If the thickness is less than 0.4 mm, the burning rate becomes high and it becomes difficult to satisfy the target flame retardancy standard. This leather-like sheet substrate can be dyed with a usual dyeing method using a slene dye or a metal-containing dye, and by fluffing its surface, it becomes a suede-like artificial leather. Such artificial leather is used for shoes,
In addition to miscellaneous goods such as bags and accessory cases, it can be used for interior goods such as upholstery for sofas and for clothing. The flame-retardant leather-like sheet of the present invention is particularly used for applications such as upholstery for vehicle seats such as automobiles, railway vehicles, airplanes, ships, etc., which require anti-fusible properties, flame retardancy, etc., and which require strength. Substrates are suitable. The soft texture of the leather-like sheet substrate is made into a silver-tone artificial leather by melting and smoothing the surface, or by coating a resin on the surface and imparting natural leather-like surface irregularities to the surface. It is also suitable in this case.

[0034]

EXAMPLES The present invention will now be specifically described with reference to Examples.
The present invention is not limited to these examples. Parts and% in the examples relate to weight unless otherwise specified. [Melting Point of Ethylene-Vinyl Alcohol Copolymer] DS
Using C (TA3000, Perkin Elmer), the measurement was carried out in a nitrogen atmosphere under the conditions of a sample of 10 mg and a heating rate of 10 ° C./min. [Melt viscosity of ethylene-vinyl alcohol copolymer]
Melt index (MI: g / 10min, load 2160g, measurement temperature 190
C) was used as an index of melt viscosity. [Basis weight] The weight W of the test piece cut into a 10 cm square was measured by an electronic balance (METLER: AE160) to obtain W / 0.0.
The grammage (g / m ² ) was calculated according to 1. [Flame retardancy test method] Automotive interior material test method JIS D12
According to 01. [Tobacco fusion resistance] On a test piece cut into 5 cm x 5 cm,
Tabaco (Longose, Japan Tobacco Inc.) ignited about 5 cm from the tip is vertically supported and brought into contact with its own weight. Five seconds after the contact, the tab is removed, the contact surface is observed, and the average of three times is evaluated as follows. Pass grade 4 or higher.

[0035]

[Table 1]

EXAMPLE 1 Methanol was used as a polymerization solvent, and AIBN (azobisisobutyronitrile) was used as a polymerization initiator.
The ethylene and vinyl acetate were radically polymerized at 0 ° C. under pressure to produce an ethylene / vinyl acetate copolymer having an ethylene content of 44 mol%. Next, this ethylene / vinyl acetate copolymer was subjected to saponification treatment in a caustic soda-containing methanol solution, followed by repeated washing using a large excess amount of pure water to which a small amount of acetic acid was added. The washing with pure water was repeated. Then, after water was separated from the copolymer by a dehydrator, it was sufficiently dried by vacuum drying at a temperature of 100 ° C. or lower. The obtained ethylene-vinyl alcohol copolymer has a saponification degree of 99.5 mol% and a melt index (190 ° C., under a load of 2160 g) of 5.5 g / 10 mi.
n, the melting point was 165 ° C.

The ethylene-vinyl alcohol copolymer obtained above was used as an island component, and nylon 6 (sea component 1, Ube Industries; UBE nylon 1011) and low density polyethylene (sea component 2, Mitsui Chemicals; Mirason FL60) were used. A 16-island composite spun fiber (sea-island ratio 6: 4, sea 1: sea 2: island = 3: 3: 4) using the mixture of No. 1 as the sea component at a spinning temperature of 250 ° C. and a spinning speed of 800 m.
/ Min of melt spinning, stretched 3 times in warm water at 80 ° C, dried by mechanical crimping, cut into 51 mm staples with a fineness of 5.2 decitex, and weighted by the cross lap method. Forming a web of 500 g / m ² ,
Next, needle punching at 1050 P / cm ² was performed alternately from both sides. Further, after shrinking in hot air at 90 ° C., it was pressed with a calendar roll to prepare an entangled nonwoven fabric having a smooth surface. The unit weight of this entangled nonwoven fabric was 600 g / m ² , and the apparent specific gravity was 0.36 g / cm ³ . 40% of aluminum hydroxide having an average particle size of 1 μm was added to 100 parts of a dimethylformamide (DMF) solution of polyurethane having a solid content of 14% mainly composed of polycarbonate polyurethane in this entangled nonwoven fabric.
After impregnating the impregnating liquid (polyurethane / aluminum hydroxide = 10.050) prepared by adding 17.5 parts of the dispersed liquid and immersing it in a DMF / water mixed liquid for wet coagulation,
The sea component 2 polyethylene in the composite spun fiber is eluted and removed in hot toluene to develop an ultrafine fiber bundle, and the thickness is 0.8 m.
A leather-like sheet substrate having m and basis weight of 420 g / m ² was obtained. The average fineness of the ultrafine fibers made of the ethylene-vinyl alcohol copolymer was 0.12 decitex, and the average fineness of the ultrafine fibers made of nylon was 0.002 decitex. The proportion of the ethylene-vinyl alcohol copolymer in the fiber component is 56%, the nylon component is 44%,
The weight ratio of aluminum hydroxide-containing polyurethane in the leather-like sheet substrate was 32%.

The obtained sheet substrate was immersed in the treatment liquid shown below and subjected to acetal decomposition regeneration treatment at 90 ° C. for 40 minutes. There was almost no change in the texture of the base fabric after the treatment, and it had sufficient strength and physical properties as a leather-like sheet. Treatment liquid: 1,1,9,9-bisethylenedioxynonane 5g / L Labaison 0.5g / L (active ingredient; sodium dedecylbenzene sulfonate manufactured by Matsumoto Yushi Co., Ltd.) PH 2.4 (PH adjustment with maleic acid)

This leather-like sheet substrate was dyed with a metal-containing dye and further raised to give a suede-like artificial leather. The obtained artificial leather was excellent in color development, soft and had a new texture. Dye: Irgalon Red 2GL200% 10% owf Temperature x time: 90 ° C x 60 minutes This suede-like artificial leather has a good anti-fugitive property of 4-5 grade, and has a slow flammability (combustion rate 7. It was determined to be 6 cm / min) and was excellent in flame retardancy.

Example 2 A 60-micron-thick polyurethane layer was applied to the surface of the leather-like sheet substrate after acetal decomposition and regeneration treatment obtained in the same manner as in Example 1 to give a natural leather-like embossed pattern. After rubbing, a leather-like sheet with a silver surface layer having excellent flame retardancy and a soft texture was obtained.

Comparative Example 1 An attempt was made to obtain a suede-like artificial leather in the same manner as in Example 1 except that the ethylene content of the ethylene-vinyl alcohol copolymer was changed to 10 mol%.
It is thought that gelation occurred during spinning, but many screws fell off, and spinning and winding could not be performed.

Comparative Example 2 A suede-like artificial leather was obtained in the same manner as in Example 1 except that the ethylene content of the ethylene-vinyl alcohol copolymer was changed to 90 mol%. The obtained artificial leather was excellent in color developability and strength physical properties, but was inferior in tobacco melting resistance (second grade) and flame retardant performance (flammability).

Comparative Example 3 The core component was an ethylene-vinyl alcohol copolymer, and the sheath components were nylon (sheath component 1) and polyethylene (sheath component 2).
A core-sheath composite spun fiber composed of a mixture of
Core: sheath 1: sheath 2 = 5:25:25), and the core component is 2
An attempt was made to obtain a suede-like artificial leather in exactly the same manner as in Example 1 except that a decitex was used. The ratio of the ethylene-vinyl alcohol copolymer in the fiber component was 67% and that of nylon was 33%. The obtained artificial leather had a hard texture and was inferior in appearance because sufficient lighting could not be obtained.

Comparative Example 4 Nylon 6 (sea ingredient 1, Ube Industries; UBE nylon 1011)
And low density polyethylene (sea component 2, Mitsui Chemicals; Mirason FL6
0) was mixed at 5: 5, and a suede-like artificial leather dyed in dark color was obtained in exactly the same manner as in Example 1 except that the spinning temperature was 280 ° C. The average fineness of the ultrafine fibers made of nylon was 0.002 decitex. The proportion of ethylene-vinyl alcohol copolymer in the fiber component is 0%, and nylon is 100%. The obtained product was excellent in strength physical properties and color developability, but was inferior in tobacco anti-fusible property (second grade) and flame retardant performance (flammability).

Comparative Example 5 The ethylene-vinyl alcohol copolymer used in Example 1 and low density polyethylene (sea component 2, Mitsui Chemicals; Mirason FL)
60) was mixed at 5: 5, and a suede-like artificial leather dyed was obtained in exactly the same manner as in Example 1 except that the spinning temperature was 250 ° C. The average fineness of the ultrafine fibers made of the ethylene-vinyl alcohol copolymer was 0.008 decitex. The proportion of ethylene-vinyl alcohol copolymer in the fiber component is 100%, and that of nylon is 0.
%. The artificial leather thus obtained had low strength and physical properties, and sufficient coloring was not obtained with the metal-containing dye.

Comparative Example 6 A suede-like artificial leather was obtained in exactly the same manner as in Example 1 except that aluminum hydroxide was not added to the impregnating liquid. Although it was excellent in strength physical properties and color developability, it was inferior in tobacco melting resistance to Grade 4, which was inferior to that of Example 1, and was judged to be easily combustible in the JIS D1201 flammability test. It was not flammable.

[0047]

INDUSTRIAL APPLICABILITY The present invention can provide a leather-like sheet substrate having not only excellent anti-fusing property, flame retardancy and dyeability but also sufficient strength and a new soft texture.

Continued front page    F term (reference) 4F055 AA21 BA12 CA11 EA05 EA07                       EA12 EA24 EA34 FA20 FA21                       FA40 GA02

Claims (4)

[Claims] 1. A leather-like sheet substrate comprising a non-woven fabric in which ultrafine fibers (A) of 0.5 dtex or less are three-dimensionally entangled and a polymeric elastic body (B), and the ultrafine fibers (A) are 30 to 90. % By weight, ethylene content 25-7
0 mol% ethylene-vinyl alcohol copolymer, and 10-70 wt% nylon,
Further, the polymer elastic body (B) has the same structure as the polymer elastic body (B) 100.
A leather-like sheet substrate comprising 10 to 200 parts by weight of aluminum hydroxide with respect to parts by weight. 2. The ethylene-vinyl alcohol copolymer has a unit having a sulfonic acid group or a sulfonate group in the main chain, and the amount thereof is the total number of moles of ethylene units and vinyl alcohol units constituting the basic skeleton. For 0.
The leather-like sheet substrate according to claim 1, which is in the range of 05 to 1.0 mol%. 3. The leather-like sheet substrate according to claim 1, wherein the ethylene-vinyl alcohol copolymer is acetalized. 4. A process for producing a leather-like sheet substrate comprising a non-woven fabric in which ultrafine fibers (A) having a size of 0.5 decitex or less are three-dimensionally entangled and a polymeric elastic body (B). A step of producing an entangled nonwoven fabric composed of ultrafine fiber-generating fibers in which two components of fibers are an ethylene-vinyl alcohol copolymer and nylon, and a polymer elastic body containing aluminum hydroxide in the entangled nonwoven fabric (B And a step of converting the ultrafine fiber-generating fiber into a bundle of ultrafine fibers having 0.5 decitex or less, in the order of or.