CS205260B1 - Soft flat porous material with improved resistance to cyclic bending and method of its manufacture - Google Patents

Description

BACKGROUND OF THE INVENTION The present invention relates to a soft sheet of porous material prepared from an elastomeric material optionally combined with a fibrous material and to a process for the manufacture of this material.

Synthetic sheet materials, which are used as a substitute for natural leather, are most often represented by a polymeric elastomeric composition optionally combined with a fibrous material. In order to achieve hygienic properties, the polymer mass is converted into a porous form during the manufacturing process. It then finds use as a self-supporting polymer film, to which the pigmented rinsing layer imparts liquid water impermeability and suitable organoleptic properties. To limit the ductility, the porous polymeric mass as a cover layer is bonded to an adjacent textile woven or nonwoven layer. This textile layer is interconnected with a polymeric binder, preferably also in a discontinuous form, to improve the bending properties.

Polyether and polyester linear or near-linear polyurethanes or polyurethane ureas are most commonly used as porous polymeric materials, but also aqueous dispersions of butadiene-acrylonitrylstyrene copolymer for impregnation. They are converted into a discontinuous porous form in the production process by coagulation in a solvent-water mixture or by evaporation of the dispersion medium, possibly after previous thermo-coagulation and vulcanization.

These materials can be used in many branches of consumer industry, clothing, haberdashery, but the most common is their application in the form of uppers for shoe production.

Such material is subject to high demands, both from the processor and from the user of the products made from these materials.

One of the most desirable properties of synthetic leather replacing natural leather is softness, flexibility of material, which is positively reflected in the comfort of worn footwear and other products. However, the significant softness of the material must not be at the expense of deterioration of other properties, of which bending in particular is of paramount importance.

Indeed, it is a general experience that an improvement in one property, for example strength parameters, leads to a deterioration of another property, such as resistance to multiple Bally-bending.

therefore, the use of particularly soft fiber substrates and polymeric materials for their inadequate strength parameters is not appropriate. Conversely, the use of dense fibrous substrates and hard polymeric materials provides the required strength properties, but these materials do not have satisfactory bending properties.

In the field of fiber raw materials, there is a way to arrive at a soft product having bending and strength parameters at the desired level. For example, the use of islet-like fibers in the sea or core-sheath. However, the production of these fibers is very costly, technologically demanding, and also introduces a number of complications into the subsequent technological process.

At the stage of processing the fibrous substrate to form a skin-like material, there are possibilities to influence the properties of the resulting product. It is impregnation with polymers of different modulus or solutions or dispersions of different polymer content. However, the practical outcome of these methods is very limited. Impregnation with solutions or dispersions with low polymer content is accompanied by a significant deterioration of the resistance to repeated bending of Bally, a significant change in the modulus of the starting polymer is associated with a change in the heat resistance of the polymer. In the manufacture of polymer leather without a textile layer or in the production of opaque polymer porous deposits, the properties of the polymer material can be controlled by the choice of polymerization components, in the case of polyurethane in particular by the choice of polyethers or polyesters, diisocyanates and extenders. A number of properties, including for example the coagulation rate, can be controlled by the addition of a suitable modifying polymer, most often vinyl. Methods are also known which use mixtures of elastomeric materials consisting of a polyurethane elastomer and a copolymer derived from vinyl or acrylic monomers and compounds of the formula XCH = CYX to improve some properties, wherein at least one of X or Y is an acrylic group or a derivative thereof and the remaining substituents may be selected from -H, -CH4, -CgH4, -CN, -CONHg, -COOR, optionally adding polymers of aliphatic monomers.

Stiffness, mechanical resistance can be controlled by the addition of inorganic or organic fillers such as carbon black, salts.

According to some processes, the addition of higher alcohols or higher fatty acids makes it possible to control the precipitation rate of polyurethane solutions in the preparation of porous structures.

The disadvantage of these filters is that they are transferred to the coagulation baths, some of them deteriorate the quality of the micro-porous structure and its physico-mechanical properties, and migrate to the surface of the body for a longer period of time, thereby deteriorating the quality of surface treatments.

However, polyvinyl chloride-type modification polymers or the above-mentioned vinyl or acrylic-type copolymers solidify and deteriorate its resistance to multiple Bally bending at normal and low temperatures. This parameter is one of the decisive factors for the utility properties of the sheet-like flexible structures.

These disadvantages are largely eliminated by the soft sheet material and the process according to the invention, characterized in that the self-supporting layer consists of a mixture of a porous polymeric elastomeric material and a modifying agent, which is a silicone oil or a silicone oil in combination with polypropylene oil. in a ratio of 5:95 to 95: 5 in an amount of 0.2 to 50% based on the elastomer mass, wherein the structure of the polymeric elastomer mass can be permeated by the fibrous mass and that the elastomer mass solution or dispersion is mixed with the modifying agent in a ratio of 1: 0.005 up to 1: 0.5 parts by weight, based on the dry weight of the elastomeric mass, the resulting mixture is applied to or bonded to a temporary backing, or bonded and applied to a fibrous formation, the polymeric mass and modifying substance mixture is then solidified by coagulation in a further step; or by evaporation of the volatile environment.

The mechanism of action of silicone oil is not clearly explained. Some works try to explain its effect in influencing adhesion of binder - fiber. However, this explanation is not sufficient. It is precisely from the invention that its internal lubrication effect results in the preparation of a self-supporting single-layer synthetic leather. According to the latest knowledge, the modifying agents cause swelling of the fiber surface layer, which contributes substantially to the physico-mechanical properties of the fiber as a whole. It is precisely these phenomena that are attributed to the newly discovered and proven effect of the inventive blend of elastomeric mass and silicone oil, optionally in admixture with polypropylene oil, which causes a marked increase in resistance to cyclic bending stress. The amount of the modifying agent, but only up to a certain limiting content, and above all the chemical similarity or affinity of the fiber and the modifying substance and the consequent ability to penetrate into the surface layer of the fiber appear to be decisive for the lubricating effect.

The elastomeric polymer is typically a polyurethane prepared by reacting a polyether or polycaprolactone diol with a diisocyanate with a bifunctional chain extender, such as hydrazine, ethylenediamine, or butylene glycol, most preferably in dimethylformamide. The solution of this polymer can be modified by adding another polymer, of which polyvinyl chloride is the most commonly used. However, this polyvinyl chloride addition is less suitable to achieve high low temperature bending resistance. Especially for the bonding, aqueous dispersions of elastomers prepared by copolymerization of butadiene, styrene and acrylic acid derivatives can be advantageously used. The fibrous substrate used, most commonly a nonwoven fibrous layer, can be made by known techniques such as needling and shrinking, by a papermaking process, or by spinning. The woven or knitted textile layer may, alone or interconnected with the polymeric binder, form a reinforcing carcass or reinforcement of the laminate. The polymer blends of the present invention may be formulated by conventional methods, in particular, pigmented, stabilized, and the like.

The formations can also be further customized by conventional techniques, in particular providing the desired design, pigmented finish enhancing mechanical resistance, liquid impermeability, and the like.

The following examples are intended to illustrate the invention in more detail, but do not limit it.

He did

From a 20% solution of linear polyurethane urea in dimethylformamide prepared by the reaction of polyethylene butylene adipate with a mol. Weight of 1,800 and diphenylmethane diisocyanate and butylene glycol as chain extenders two types of solutions were prepared according to the following recipes:

A) 100 h.d. 20% solution of polyurethane in dimethylformamide for 15 h.d. mixtures containing

- 15 h.d. - ,, 5 h.d. Coagulant, 28% solution 20% solution  synthetic tannins 50% ro - 1, 0 h.d 15 h., i. a batch containing - 30 h.d. powder pigment - 1 0 h.d. a hydrolytic stabilizer - 10 h.d. UV-stabilizer - 50 h.d. dimethylformamide-water 1: 1

B) in addition to the above ingredients

h.d. methylphenylsilicone oil.

*

The mixtures were treated in the same way for a longer time: a 2.4 mm deposit was precipitated on a temporary substrate in a dimethylformamide-water bath with a diminishing dimethylformamide content, after being solidified free of dimethylformamide by removal and dried at 120 ° C.

In the Bally flexometer test, the multiple bend resistance test showed Sample A of 2/2, Sample B of 4/4 (Scales 5 to 1, 5 Best, Face / Back). In the stiffness evaluation with the initial modulus of elasticity θθ determined on the Instron instrument, sample A showed a value of 8.6 MPa and sample B a value of 6.4 MPa.

Example 2

A nonwoven fibrous layer prepared from a blend of polypropylene fibers (30%) and polyethylene terephthalate (70%) by needling and shrinkage was impregnated with a 12% solution of polyurethane prepared by reacting polypropylene glycol with a mole. weight of 1500, diphenylmethane diisocyanate and hydrazine hydrate as chain extenders, in the first case without the addition of silicone oil, in the second case containing Si-oil of type M-200 in an amount of 22 g / 1 kg of impregnating solution. Coagulation was performed in a dimethylformamide-water bath containing 30% dimethylformamide for 20 min, then the dimethylformamide was removed from the sheet by scrubbing, dried at 120 ° C, sanded on both sides and split into two equal halves. In the multiple bending test on a Bally flexometer, the samples showed the following degree of damage:

+ 22 ° C - 25 ° C 100 CZK 200 kC 25 kC 50 kC standard 5/5 3/3 4-3 / 3 1/1 sample with addition Si-oils 5-5 5 / 5-4 5-4 / 5 3/3 A significant reduction in stiffness was manifested in values initial Stiffness module as follows: Εθ (MPa) standard 16.1 / 11.3 pattern with addition Si-oils 8.6 / 5.2

Example 3

The fibrous layer prepared as in point 2 but from a mixture of 40% polyurethane and 60% polyethylene terephthalate fibers having a density of 200 kg / m @ 2 was impregnated with a mixture of carboxylated acrylonitrylbutadiene copolymers latex, coagulation paste, vulcanizing agent, kaolin as filler. without addition of methyl silicone oil according to recipes (parts by weight):

recipe

component AND (B) Latex 100 ALIGN! 100 ALIGN! coagulation paste 8.5 8y5 pigment, disp. 30% 1.5 ’, 5 vulcanizing paste 0.5 0.5 silicone oil 6 -

After adjusting the binder content to 40% by de-aging, the thermosensitive latex was coagulated by thermal shock at a 2 min exposure. at 120 ° C, then emulsifying ingredients were removed from the formation by scrubbing, and the copolymer was converted to the final vulcanization at 130 ° C for about 30 min. After final treatments such as grinding, splitting, the samples were subjected to cyclic flexural resistance evaluation on a Bally-flexometer at 23 ° C.

100 kC 150 kC sample A 4/4 3/3 sample B 3-2 / 2 1/1

In addition to significant improvement in cyclic stress resistance, sample A also exhibited significant softening.

Example

The double-brushed fabric of a mixture of polyethylene terephthalate fibers (65%) and viscose (35%) was impregnated on the treated impregnation machine and simultaneously coated with 6% polyester-polyurethane solution containing 3.8% silicone oil type M-500 based on polyurethane dry matter. The deposition was coagulated in a 20% dimethylformamide bath in the following procedure, after solidification, the dimethylformamide was removed by washing and dried. The material thus obtained was surface treated with a polyurethane surface treatment of a temporary, desirably separating pad. The material is designed for uppers of shin shoes and for clothing applications.

The material exhibited a degree of damage of 5 / 5-4 at 100 kC when evaluating cyclic stress resistance. The material prepared in the same manner, but with no Si-oil added to the impregnation solution, showed a B / B damage level of 4/3 at 100 kC.

Example 5

A nonwoven fibrous layer of 70% polypropylene and 30% polyamide fibers having a density of 300 kg / πΡ was made by needling, shrinking and post-compaction on a hot and wet press. Polyurethane was prepared by reaction of 4,4'-diphenylmethane diisocyanate, 1,500 average molecular weight polypropylene glycol and hydrazine in dimethylformamide.

The polyurethane solution was adjusted to a dry matter content of 12% and a Si-oil content of 0 and 33%, respectively, based on the dry matter of the polymer, by adding pigment, stabilizers, dimethylformamide and alternatively methyl silicone oil. The resulting viscosities of the solutions were 0.305 and 0.32 Pa.s / 30 ° C, respectively. The nonwoven fibrous layer was impregnated with the treated solutions to a 30% binder content in the dry product. Further processing of the impregnated nonwoven fibrous layer was the same as in Example 2. The obtained undercoat was laminated to a 1.2 mm 20% polyurethane solution prepared from the above raw materials, silicone oil was added in an amount of 0.2% by weight of the polyurethane dry weight.

The coagulation was carried out in the first stage in a steam atmosphere with 92% relative humidity at 31 ° C, in the second stage in a bath containing 30% dimethylformamide at 35 ° C. After removal of the dimethylformamide and drying of the moisture, the material was surface treated. The basic coating consisted of a layer of polyacrylate applied by spraying, followed by a design by design, the final treatment was carried out with a solution type of polyester polyurethane.

The following results were obtained when comparing both materials with the Bally-test:

150 kC 200 kC standard 4/3 3/1 material with addition of 5-4 / 5 Si-oil

4/4

Example 6

The fibrous layer was prepared and treated for coagulation as in Example 5. After solidification by coagulation, the material was dehumidified by peeling off and a partially dried surface was coated with a polyurethane solution prepared according to recipe B of Example 1. Coagulation in a 40% dimethylformamide-water bath followed. washing the dimethylformsmide and drying. The lower part of the undercoat was chipped, the upper with the polyurethane deposit in microporous form was surface treated as in Example 5. The material used in the preparation was an impregnating solution with the addition of Si-oil. 200 kC, standard material at the same load 3/2. The softness expressed by the initial modulus of elasticity E _Q was 24 / 16.3 MPa for the first sample and 38.2 / 31.8 MPa for the second sample.

Claims (8)

SUBJECT OF THE INVENTION 1. Soft sheet of porous material with increased resistance to repeated bending, consisting of a self-supporting layer which can be surface-treated on one or both sides, characterized in that the self-supporting layer consists of a mixture of porous polymeric elastomeric material and a modifying substance, silicone oil; or silicone oil in combination with polypropylene oil in a ratio of 5:95 to 95: 5, in an amount of 0.2 to 50% based on the elastomer mass, wherein the structure of the polymeric elastomer mass can be permeated by the fibrous mass. 2. A soft sheet material according to claim 1, characterized in that the mixture of polymeric elastomer and modifying substance which is permeated by the fibrous material simultaneously forms at least one surface layer. 3. The material according to claim 1, wherein the polymeric elastomeric material is a linear or near linear polyurethane or polyurethane prepared by reacting a polyether or polyester type polyol, diisocyanate and a bifunctional chain extender, optionally mixed with polyvinyl chloride or a copolymer prepared by at least polymerization. two styrene monomers, butadiene, an acrylic acid derivative, or a mixture of these copolymers. 4. A material as claimed in any one of claims 1 to 3, wherein the silicone oil is an alkyl, aryl and / or alkylaryl polysiloxane having a viscosity of 0.01 to 20 Pa.s / 25 ° C. 5. The material of claims 1 to 3, wherein the polypropylene oil is a blend of polypropylene homologues having a carbon number of 6 to 90 and a viscosity of 0.05 effith 20 Mp / 25 ° C. 6. A material as claimed in any one of Claims 1 to 5, characterized in that the fibrous material contained is a non-woven fibrous formation of synthetic fibers or a mixture thereof. 7. A method according to claim 1, wherein the solution or dispersion of the elastomeric material is mixed with the modifying agent in a ratio of 1: 0.005 to 1: 0.5 parts by weight, based on the dry weight of the elastomeric material. The mixture of polymeric material and modifying agent is then consolidated in the next step by coagulation and / or evaporation of the volatile medium. 8. A method according to any one of claims 1 to 6, wherein the blend of the polymeric elastomeric material and the modifying agent is bonded and applied in two separate steps and the deposition is carried out after partial or complete consolidation of the polymeric elastomeric material.