SU722495A3 - Microporous synthetic leather - Google Patents

Abstract

1483453 Porous composite elastomer sheet PORVAIR Ltd 25 July 1974 [25 July 1973] 35469/73 Heading B2E [Also in Division C3] A water-vapour-permeable soft flexible sheet #0.8 mm thick, has #3 superimposed porous layers of elastomeric polymer; is free from fibrous reinforcement and has elongation at break >200%; and comprises, in order, a flesh-coat layer (a), a strength-imparting substrate layer (b), and a topcoat layer (c), (b) having greater density than (a) and (c), the combined thickness of (a) and (c) being 30- 175% of the thickness of (b). (a) and (c) may adhere integrally to (b). The sheet may be made by: successively depositing coagulable elastomeric polymer composition layers (A), (B) and (C) respectively, containing removable particulate filler (F A ), (F B ), and (F C ) respectively; layer (A) being deposited on a porous support to form (a), then, prior to coagulation of (A), layer (B) is deposited on (A), and then, prior to coagulation of (A) and (B), layer (C) is deposited; the composite material is then coagulated. (F A ) and (F' C ) have mean particle size smaller than (F B ). The coagulation may be performed by contact with a non-solvent, e.g. water, and the fillers may be leached out. The filler may be NaCl or other inorganic salt. The non-solvent may comprise 0-30% solvent and 0-15% of the filler substance. Composition (B) may comprise a 25-40% wt solution of a polyurethane in a polar organic solvent (S B ) with filler (F B ) dispersed therethrough, (F B ) being insoluble in (S B ), (F B ) having average particle size 20-200 Ám, where (F B )/(F B ) polyurethane polyurethane weight ratio is from 1.8 to 2.7; and where (F A ) and (F B ) have average particles size <20 Ám. Each layer (a), (b) and (c) may be microporous, having randomlydistributed compact voids intercommunicating via pores penetrating the walls between the voids, the thickness of these walls being greater in (b) than in (a) or (c). Layer (b) may be 0.5-1.5 mm thick, have a total void volume or porosity 50-65% where #50% of the porosity is due to interconnecting pores and voids, the pores having diameter 5-100 Ám; non-interconnecting pores may have diameter 1-30 Ám, being 1-10 Ám apart, and may occur in regions the majority of which are 30-100 Ám thick between adjacent voids. Layers (a) and (c) may have voids 5-75 Ám wide, separated by walls 1-5 Ám thick having pores passing through. The polymer may be: in (b), a polyester-polyurethane, and in (a) and (c), a polyester-urethane or polyether-urethane having lower Shore hardness than that of (b): or the same polyurethane may be used for all 3 layers. The cut tear strength may be #1.5 kg, and (cut-tear strength)/stiffness may be >4.2. Topcoat (c) may be finished to form a thin densified permeable layer, #30 Ám thick, at the outer surface of (c).

Description

(54) MICROPOROUS ARTIFICIAL LEATHER

The mixture is heated to 60 ° C and maintained for 1.5 hours with stirring. The excess unreacted isocyanate is determined by titration. A sufficient amount of butandio; 1a (3.0 parts) is then added to conduct a strictly stoichiometric reaction with unreacted isocyanate. The mixture is then kept at 60 ° C and stirred while periodically measuring the viscosity until it reaches a value of about 3500 P and 24 ° C. Thereafter, 4.10 parts of 1,4-butanediol, dissolved in 3.5 parts of N, N-dimethylformamide, are added as an agent to terminate the reaction.

The nitrogen content is about 4.5%, and the polyester content is about 50%. Polyurethane in the form of a solid long sheet at 25 ° C has a Shore 55 hardness.

Polyurethane 2. All operations are the same as in the case of polyurethane 1, but the quantities of reagents have been changed (the content of the components is given in hours):

DMF900

d-Toluensulfonyl 0.06

Dilaurate dibutyl tin 0,027

Complex iolifir282,4

Butandiol5

4,4-Diphenylmethane diisocyanate 132, 6

Butandiol5

Butandiol5

DMF100

You get a polymer with a nitrogen content of 3.3%.

The solution has a viscosity of 4100 n at 33.2% solid matter, at 24 ° C, a characteristic viscosity of 1.145, to 0.48.

Polyurethane 3. All operations are carried out as in the case of polyurethane 1, but the amount of reagents varies and a polyester with a molecular weight of 2250, the final hydroxyl groups having an acid number less than 2 and a hydroxyl number of 50 ± 2 mg CPC per 1 g is used. Components to obtain PU, including: DMF900

l-Toluenesulfonic acid 0.06

Dilaurate dibutyl tin 0,027

Polyester271.3

Butandiol 33,0

4,4-Diphenylmethane diisocyanate140, 6

Butandiol5,1

Butanediol5.0

DMF100

You get a polymer with a nitrogen content of 3.5%.

The solution has a viscosity of 3400 P at 3.2 7 ° solid matter, at 24 ° C, an intrinsic viscosity of 1.11 and ≈ 0.49.

Polyurethane 4. All operations are carried out as in the case of polyurethane 1, with the exception of the absence of a catalyst component, dilaurate dibutyl tin. The following quantities of reagents are taken, including: DMF 900.00

rt-Gluolsulfonic acid 0.06

Simple polyether254,20

Butandiol38.30

4,4-Diphenylmethaned nisocyanat152, 70

Butandiol3,00

Butandiol5,00

DMF20.00

A polymer with a nitrogen content of 3.8% is obtained. Polyether is polytetramethylene glycol,

having a molecular weight of 1930 and terminal hydroxyl groups, a hydroxyl number of 53-59 and a very low acid number not exceeding 0.05 mg KOH per 1 g. It has a melting point of 38 ° C and

specific gravity 0.985 g / cm at a temperature of 25 ° C.

The polymer solution has a viscosity of 4400 P at 33.2% solids at 24 ° C, a characteristic viscosity of 0.88 dl / g and

65

Example 1. The example illustrates the three-layer artificial skin in accordance with the invention. The base has a coarser porous structure than the surface layer and a soft layer made of a softer polymer (polyurethane) than the base.

The following procedure is used to form tight layers.

First, a paste of a soft layer is spread on a porous plastic sheet, after which the paste of the base is applied and then a paste of the surface layer is spread on it. Then stuck-on pasted layers of pastes on a porous substrate are immersed in clean wastewater (equally effective mixtures of aqueous salt solutions) at 30 ° C for 1 hour with the polymer surface down in order to coagulate the polymer in the present in a self-supporting form. The composite three-layer material is then stripped from the substrate without tearing — L is immersed in water at 60 ° C for 5 hours in order to completely remove dimethylformamide and reduce the content of water washable filler — sodium chloride to a very low level, for example, much less than 1000 mg / m so that accurate density measurements can be made.

The material is then dried in air at 70 ° C for 2 hours.

The base paste is prepared by mixing and grinding a solution of polyurethane 1 (diluted to 32% concentration) from 1.90 parts to 1 part of polyurethane sodium chloride particles having an average particle size of 27 microns (negative deviation of 12 microns, positive deviation of 21 microns) subsequent removal of air in a vacuum.

The paste of the surface layer and the soft layer was prepared from a solution of polyurethane 2 softer than PU base (diluted to 25% of concentration), mixed and ground from 3 parts to 1 part of Zfatana sodium chloride, having an average particle size of 9 µm ( negative deviation - 3 microns, positive deviation +4 microns), followed by removal of air in a vacuum.

Example 2. Trilayer faux leather is similar to Example 1, but having a thicker base with a less coarse structure.

This material was prepared according to the same procedure as Example 1, the only difference being the use of sodium chloride having an average particle size of 14 µm (negative deviation of 6 µm, positive deviation of 15 µm) for the base paste.

A single-layer material made from a paste of the base has a density of 0.56 at the same thickness.

Example 3. Three-layer IR, similar to Example I, but having different polymers in the surface and soft layers.

The method and formulations of manufacture are the same as in example 1, the only difference is that for the surface and soft layers a solution of polyurethane, described above as polyurethane 3, is used, and that the layers have different thickness.

Examples 4-5. Three-layer IR, similar to example 1, but have a different polymer, namely polyurethane 3, in the composition of the pastes of the surface and soft layer. The base paste is also prepared with coarser sodium chloride with an average particle size of 31 µm (negative deviation of 12.5 µm, positive deviation of 18 µm) and with 2.0 parts of salt per 1 hour of polymer. Excluding these differences, the method and formulations are the same as in example 1.

Example 6. Three layer IR, similar to example 1, but having a different polymer, namely polyurethane 3 described above, in the composition of the pastes of the surface soft layer. The base paste was also prepared using coarser sodium chloride with an average particle size of 49 µm (negative deviation of 18.5 µm, positive deviation of 31 µm) and with 2.2 parts of salt per 1 hour of polymer. Excluding these differences, the method and formulations are the same as in example 1.

Example 7. Three-layer IR, similar to example 1, but having a different polymer, namely polyurethane I described above, in the composition of the surface and soft layer.

The method and formulation of production are the same as in example 1, except that

in the base paste, sodium chloride is applied to polyurethane, 1.9 parts and 1 hour. Examples 8-9. Three-layer IR, similar to example 1, but prepared with

using salt with a smaller particle size for the base and a harder polymer for the surface and soft layers, namely the same polyurethane 1 that is used for the base.

The surface layer, base, and soft layer were applied, coagulated, leached, and dried in the same manner as described in Example 1.

The basic formulation is different from the example.

1 using sodium chloride with an average particle size of 17 µm and using a ratio of sodium chloride to polyurethane of 2.05 parts per hour. The formulations for preparing the soft and surface layers are the same as

used in example 1, except for differences in polyurethane.

In all these examples, the materials have an elongation at break in the region of 375-500%.

Examples 10-24. Examples 10-13 and 14-17 illustrate the effect of varying the thickness of the substrate, examples 18-24 illustrate the effect of changing the ratio of salt to polymer. In all these examples, the materials have an elongation at break of the 375-500% region.

Material properties are listed in the table.

Examples 25-31. These examples illustrate (Example 25) the use of polyurethane based on ether (the above polyurethane 4) for the outer layers, and in other iriamers the effect of a change in the ratio of the thickness of the layer and the grip.

Comparison of examples 26 and 27 shows that, by applying a standard surface layer on either side of the substrate, it is IMPOSSIBLE to achieve only a slight increase in the ratio of the stress gap to stiffness. Comparison of examples 28 and 27 shows that the use of more SOL1G at the base greatly improves the ratio of tensile stress to hardness, while comparison of examples 28 and 29 shows a further increase in this otisheii, obtained by reducing the thickness of the base.

Comparison of pairs of examples 27 and 30 and 29 and 31

accordingly, noKa3biBaf T is a strong decrease in the ratio of tensile stress to stiffness, which occurs when the base layer is not thicker and more dense than the soft and surface layers.

Examples 5 and 6 were compared with respect to their hydrolysis resistance.

Claims (1)

Invention Formula Microporous artificial leather of elastomeric polyurethane or its mixture 910 with other nOvTHMepaMH, which includes a layer of lower density than the base, with correlation n-located on it with single-layer layers in thickness - the front side surface layer layer: base: backing layer with a correspondingly smaller density than the base, differently 10-95: 100: 10-95. so that, in order to reduce the gesture-5 sources of information, bones while maintaining skin strength, taken into account when examining additionally contains on the other hand1. Patent of England No. 1220218, cl. In 2E, warp backing layer also having 1971. 722495