Classifications

• • D—TEXTILES; PAPER
  • D04—BRAIDING; LACE-MAKING; KNITTING; TRIMMINGS; NON-WOVEN FABRICS
  • D04H—MAKING TEXTILE FABRICS, e.g. FROM FIBRES OR FILAMENTARY MATERIAL; FABRICS MADE BY SUCH PROCESSES OR APPARATUS, e.g. FELTS, NON-WOVEN FABRICS; COTTON-WOOL; WADDING ; NON-WOVEN FABRICS FROM STAPLE FIBRES, FILAMENTS OR YARNS, BONDED WITH AT LEAST ONE WEB-LIKE MATERIAL DURING THEIR CONSOLIDATION
  • D04H1/00—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres
  • D04H1/40—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres from fleeces or layers composed of fibres without existing or potential cohesive properties
  • D04H1/58—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres from fleeces or layers composed of fibres without existing or potential cohesive properties by applying, incorporating or activating chemical or thermoplastic bonding agents, e.g. adhesives
  • D04H1/64—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres from fleeces or layers composed of fibres without existing or potential cohesive properties by applying, incorporating or activating chemical or thermoplastic bonding agents, e.g. adhesives the bonding agent being applied in wet state, e.g. chemical agents in dispersions or solutions
• • D—TEXTILES; PAPER
  • D04—BRAIDING; LACE-MAKING; KNITTING; TRIMMINGS; NON-WOVEN FABRICS
  • D04H—MAKING TEXTILE FABRICS, e.g. FROM FIBRES OR FILAMENTARY MATERIAL; FABRICS MADE BY SUCH PROCESSES OR APPARATUS, e.g. FELTS, NON-WOVEN FABRICS; COTTON-WOOL; WADDING ; NON-WOVEN FABRICS FROM STAPLE FIBRES, FILAMENTS OR YARNS, BONDED WITH AT LEAST ONE WEB-LIKE MATERIAL DURING THEIR CONSOLIDATION
  • D04H1/00—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres
  • D04H1/40—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres from fleeces or layers composed of fibres without existing or potential cohesive properties
  • D04H1/58—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres from fleeces or layers composed of fibres without existing or potential cohesive properties by applying, incorporating or activating chemical or thermoplastic bonding agents, e.g. adhesives
  • D04H1/587—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres from fleeces or layers composed of fibres without existing or potential cohesive properties by applying, incorporating or activating chemical or thermoplastic bonding agents, e.g. adhesives characterised by the bonding agents used
• • D—TEXTILES; PAPER
  • D04—BRAIDING; LACE-MAKING; KNITTING; TRIMMINGS; NON-WOVEN FABRICS
  • D04H—MAKING TEXTILE FABRICS, e.g. FROM FIBRES OR FILAMENTARY MATERIAL; FABRICS MADE BY SUCH PROCESSES OR APPARATUS, e.g. FELTS, NON-WOVEN FABRICS; COTTON-WOOL; WADDING ; NON-WOVEN FABRICS FROM STAPLE FIBRES, FILAMENTS OR YARNS, BONDED WITH AT LEAST ONE WEB-LIKE MATERIAL DURING THEIR CONSOLIDATION
  • D04H1/00—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres
  • D04H1/40—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres from fleeces or layers composed of fibres without existing or potential cohesive properties
  • D04H1/58—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres from fleeces or layers composed of fibres without existing or potential cohesive properties by applying, incorporating or activating chemical or thermoplastic bonding agents, e.g. adhesives
  • D04H1/60—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres from fleeces or layers composed of fibres without existing or potential cohesive properties by applying, incorporating or activating chemical or thermoplastic bonding agents, e.g. adhesives the bonding agent being applied in dry state, e.g. thermo-activatable agents in solid or molten state, and heat being applied subsequently
• • D—TEXTILES; PAPER
  • D06—TREATMENT OF TEXTILES OR THE LIKE; LAUNDERING; FLEXIBLE MATERIALS NOT OTHERWISE PROVIDED FOR
  • D06P—DYEING OR PRINTING TEXTILES; DYEING LEATHER, FURS OR SOLID MACROMOLECULAR SUBSTANCES IN ANY FORM
  • D06P1/00—General processes of dyeing or printing textiles, or general processes of dyeing leather, furs, or solid macromolecular substances in any form, classified according to the dyes, pigments, or auxiliary substances employed
  • D06P1/44—General processes of dyeing or printing textiles, or general processes of dyeing leather, furs, or solid macromolecular substances in any form, classified according to the dyes, pigments, or auxiliary substances employed using insoluble pigments or auxiliary substances, e.g. binders
  • D06P1/64—General processes of dyeing or printing textiles, or general processes of dyeing leather, furs, or solid macromolecular substances in any form, classified according to the dyes, pigments, or auxiliary substances employed using insoluble pigments or auxiliary substances, e.g. binders using compositions containing low-molecular-weight organic compounds without sulfate or sulfonate groups
  • D06P1/642—Compounds containing nitrogen
  • D06P1/645—Aliphatic, araliphatic or cycloaliphatic compounds containing amino groups

Definitions

• This invention relates to synthetic leather and, more specifically, to a process for forming a synthetic leather having the desirable inherent physical characteristics of leather.
• Patents relating to methods and techniques of preparing various synthetic leather compositions have been granted to inventors as far back as 1850'; and even before that time, a great number of attempts have been made to devise a single and rapid technique of producing synthetic leather compositions.
• pyroxylin was used to coat or impregnate various types of fibrous base materials to prepare leather substitutes.
• pyroxylin/oil/pigment compositions were widely used as coating or impregnating compositions for various woven or non-woven fibrous base materials.
• the main objective was to simulate the general appearance of leather.
• .coated fabrics particularly the vinyl coated fabrics
• leather substitutes in such applications as handbags, bookbindings, brief cases, card table covers, luggage, etc.
• the coated fabrics are satisfactory because the general appearance of leather is simulated and the coated fabrics possess some of the desirable properties of leather.
• the coated fabrics lack the properties of good tear strength, softness, and the ability to breathe or transpire water vapor and air, which are characteristic of leather; and, although the coated fabrics are used insuch applications as chair coverings, much is left to be desired, especially with respect to water vapor and air permeability.
• the ability of synthetic leather compositions to transpire Water vapor will be expressed in terms of leather permeability (LPV), as measured by the above test, in grams/ 100 sq. meters/hr. Based upon comfort tests which have been carried out, under the above conditions, the minimum tolerable leather permeability for shoe upper leather is about ],6002,000 grams/ 100 sq. meters/hr.
• the leather permeability should be 4,00020,000. Actually, there is no upper limit, but the composition must be substantially resistant to penetration by liquid water and have acceptable strength properties.
• An object of the present invention is to provide a synthetic leather having outstanding breathing qualities.
• a further object of the present invention is to provide a process of preparing a synthetic leather having the requisite properties for fabricating boots, shoes, gloves, chair coverings, and other articles wherein a composition capable of breathing is required.
• a still further object is to provide a process of preparing a synthetic leather having a tenacity, flex life, elongation, tear strength, modulus and leather permeability equal or superior to the various types of genuine leather.
• a still further object is to provide a process of preparing a synthetic leather in which the aforementioned physical properties may be tailored to the desired end use.
• the present invention comprises forming a compact, essentially water vapor-impermeable, and continuous composite sheet by hot pressing a composition comprising essentially a relatively non-extensible material, either in the form of fibers and/or discrete particles, thoroughly impregnated with a relatively extensible, substantially non-adherent, binder material, and thereafter stretching said sheet within the limits hereinafter set forth, followed by relaxing, to produce a sheet having outstanding water vapor and air permeability.
• relatively extensible material means that the material must be stretchable under the stretching forces to be employed and must elongate during the stretching and substantially recover upon releasing the stretching forces.
• relatively non-extensible material means that the material stretches to a substantially lesser extent, if at all, than the relatively extensible material under the stretching forces imposed.
• substantially water vapor-impermeable as applied to the initial composite sheet means that the sheet has a leather permeability value (LPV) of less than 1,000 grams/ 100 sq. meters/hr.
• the water vapor permeability of the initial composite base sheet is substantially no greater than that of homogeneous sheet of the relatively extensible material or the relatively non-extensible material, whichever has the higher water vapor permeability.
• the initial composite base sheet is prepared in such a manner that there are substantially no voids present in the sheet, the water vapor permeability of such a base sheet is intermediate between the permeabilities of homogeneous sheets of the two major components of the base sheet.
• the leather permeability values (LPV) of the initial compacted substantially water vapor-impermeable sheets which are transformed into permeable sheets by following the present process are low not only because the sheet is compacted by hot pressing, but also because of the thickness of the sheets which are useful for converting to synthetic leather sheets. That is, the initial sheets are usually between 0.015"0.05 in thickness, and homogeneous sheets of either the binder polymer or the structural fiber having thicknesses within this range also have low LPVs. Normally the LPV is appreciably less than 1,000, and in no case greater.
• the present invention resides in the discovery that stretching a substantially water vapor-impermeable composite sheet comprising an extensible or stretchable material and a relatively non-extensible or non-stretchable material results in the formation of a sheet which is permeable to water vapor and air.
• the degree of permeability imparted to the stretched sheet essentially depends upon the particular relatively non-extensible material employed, e. g., particulate or elongated (fibers); the particular relatively extensible material employed; the ratio of extensible and relatively non-extensible materials in the initial sheet; the extent of stretch (either in one direction or two directions); and the degree of adhesion between the two major components of the sheet.
• the stretched sheets are vapor-permeable because the internal structure of the initial sheet is modified. Stretching the initial sheet appears to pull the extensible component away from the relatively non-extensible component, and this results in the formation of voids or capillaries around the relatively non-extensible component.
• the resulting stretched sheet has a crosssectional structure essentially consisting of a binder material reinforced With the relatively non-extensible particles or fibers, the areas immediately adjacent the particles or fibers being voids. These voided areas form a structural pattern substantially identical to the distribution of the relatively non-extensible material throughout the extensible binder material.
• the relatively nonextensible material is in the form of a fibrous mat, the fibers being intertangled.
• fibrous mat as the relatively non-extensible material results in the formation of interconnecting voids or capillaries throughout the stretched sheet.
• the total volume of voids formed in the stretched and relaxed sheet depends not only on the quantity of structural fibers present in the initial, i. e., before stretching, sheet but also upon the degree of stretch and the amount of recovery of the binder polymer upon relaxing.
• the binder polymer after stretching does not recover completely, i. e., 100%, especially after being stretched as much as 40-50% in one or both directions. Incomplete recovery is evidenced by an increase in the thickness of the sheet after stretching and relaxing.
• it may be desirable to obtain almost complete recovery or a high degree of recovery because the resulting sheet would be softer and yet highly permeable because of the internal surface area formed by breaking the adhesive bonds between binder polymer and structural fibers.
• the relatively extensible material may be selected from the large class of soft, thermoplastic polymers and, more specifically, from the class of polymers which may be generally classified as elastomers or elastomeric materials, as set forth by H. L. Fisher (Industrial and Engineering Chemistry, Aug. 1939, page 942).
• Those polymers which are only partially elastic or elastomeric and are not strictly classified as elastomers include ethylene polymers such as polyethylene, chlorinated polyethylene; vinylidene chloride/acrylonitrile copolymers; various polyamides such as N-methoxymethyl polyhexamethylene adipamide; and copolyesters made from ethylene glycol, terephthalic acid and sebacic acid of the general types described and claimed in copending applications U. S. Serial Nos. 150,811 and 150,812, filed March 20, 1950, in the name of M. D.
• Patents 2,623,033 and 2,623,031 respectively polyvinyl acet'als such as polyvinyl butyral and polyvinyl laural; ethylene/vinyl acetate copolymers in which the ratio of ethylene to vinyl acetate ranges from 1.411 to 11:1.
• Polymers generally classified as elastomers include plasticized polyvinyl chloride; natural rubbers; synthetic rubbers such as neoprene (poly- 2-chloro-1,3-butadiene polymer), chloro-sulfonated polyethylene butadiene/acrylonitrile copolymers, and other butadiene copolymers. All of the foregoing may be employed with or without plasticizers.
• thermoplastic is meant' to include those polymeric materials which are at least initially thermoplastic under the conditions of hot pressing.
• initially thermoplastic includes binder materials which melt and flow under the conditions of hot pressing; and at higher temperatures, these materials, e. g., rubber and synthetic rubber compositions, may cure and be converted to a substantially t'hermoset condition.
• the relatively non-extensible material may be selected from a wide variety of materials in the form of particles of various shapes or in the form of elongated shapes such as fibers.
• the use of relatively non-extensible materials in fiber form is preferred. This is because it is desired to obtain interconnecting voids or capillaries in the resulting stretched sheets. Since the structural fibers are serving to reinforce the binder material and provide for the formation of interconnecting capillaries or pores having substantially the same interconnecting network pat' tern as that of the structural fibers, selection of fibers of a particular length and denier must be considered with these two functions in mind.
• the structural fibers should be at least about 0.5" in length.
• the strength properties of the resulting compositions do not increase appreciably when using structural fibers greater than about 1.5" in length.
• structural fibers greater than about 1.5" in length from the standpoint of handling non-woven mats of fibers on standard textile machines, it may be more convenient to use longer fibers, for example, as long as 8 or longer.
• the use of very short fibers e. g., 0.01" flock, does not produce a composition having optimum permeability.
• the length of structural fibers is increased from 0.25 to 0.5"
• the permeability appears to increase; but no appreciable increase is obtained when fibers longer than 0.5" are employed.
• fibers having a denier within a relatively wide range Normally, textile fibers having a denier Within the range from 1-3 denier/filament are employed.
• fibers having a denier as low as 5.5 l0 denicr/ filament have been used in conjunction with fibers of greater denier, e. g., 1-3 denier/filament.
• it is entirely practical to employ very thin denier fibers so long as the cohesive bonds within the fibers are greater than the adhesion between fiber and hinder, or, in other words, so long as the fibers are distinguishable as such in the fiber/binder composite.
• oriented or unoriented fibers or mixtures thereof may be employed as the structural fibers in the present compositions.
• the use of orientable, but unoriented, textile fibers is highly advantageous in preparing compositions of high tear strength and improved pliability and flex life.
• mixtures of fibers of various sizes i. e., length and denier, for the purpose of producing compositions which retain their original surface after repeated abrasions. This is accomplished by using short fibers, i. e., less than /2", in combination with the longer fibers in the structure.
• the chemical composition of the short fibers may be the same or difierent from that of the longer fibers.
• the short fibers are strategically concentrated near the surface of the initial structure in order to reduce fuzzing of the surface resulting from abrasion.
• the short fibers may be uniformly dispersed throughout the binder with the longer fibers.
• Non-extensible materials in the form of particles include pigments such as zinc oxide, talc, clay, diatomaceous earths, and various polymeric materials in particulate form such as polyamides, polyethylene terephthalate, polytetrafiuoroethylene, etc.
• non-woven fibrous mats employed in preparing the polymer-impregnated, substantially impermeable, initial sheets may be fabricated in accordance with any well known batch-wise or continuous technique such as by carding machines, air deposition apparatus, and water deposition or paper-making techniques.
• the resulting fibrous mats may have their component fibers oriented substantially in one direction or randomly arranged. Individual mats having the fibers oriented in one direction may be cross laminated. In any event, the fibers must be interconnecting so that the resulting capillaries or void spaces are interconnecting.
• the components i. e., the extensible and relatively non-extensible materials
• the extensibility of the two components must be different; the relatively non-extensible material must be relatively non-extensible as compared with the extensible material under the stretching forces (expressed in terms of per cent elongation) to which the sheet is to be subjected.
• the selected binder or extensible material must be one which can be elongated under forces which stretch the fibers to a substantially lesser extent, if at all.
• a polyamide fiber is not considered to be a non-extensible material; but in accordance with the definition employed herein, the relativelynon-extensible material is defined with respect to or in relation to the extensible material or binder employed in combination therewith.
• Adhesion between the extensible and relatively non-extensible material should be such that the adhesive bonds can be readily broken by stretching.
• the preferred or ideal case is one in which there is substantially no adhesion between the relatively extensible and relatively non-extensible material. With composite sheets fabricated from such basic components, only moderate stretchingforces are required to break the adhesive bonds and thereby form voids within the stretched sheet.
• the ratio of relatively extensible material to relatively non-extensible material in the initial sheet may vary from 30:70 to 70:30. However, the optimum quantity of extensible material in the initial composite sheet ranges from 40-60%, based upon the total weight of the two major components. Normally, the densities of the extensible material and the relatively non-extensible material are relatively close; and in such cases, the ratio of the two components may be expressed on either a volume or weight basis.
• the initial composite sheet becomes more and more permeable to vapor (the stretched sheet is highly permeable); but other properties and characteristics of the material (the stretched sheet) are not satisfactory for use as a leather replacement, for example, in boots, shoes, gloves, chair coverings, etc.
• Stretched compositions which contain too low a quantity of extensible material are extremely fuzzy at the surface, and the abrasion resistance is very poor. The general feel is more like that of felt instead of leather, and the tensile strength and tear strength are below the tensile and tear strength of materials having from 40-60% of the extensible material.
• the initial composite sheet has properties approaching those of a homogeneous film or sheet of the extensible or binder material.
• the elongation and modulus increase as the extensible or binder content is increased; and the initial vapor permeability is very low (the sheets are substantially impermeable) as is the permeability of homogeneous films of the extensible or binder polymers employed.
• the tear strength also falls off rapidly at high binder content because the film is tearing essentially as a homogeneous (non-reinforced) film. All these factors are also true for corresponding stretched sheets.
• the content of the binder or extensible material may also be varied depending upon the particular combination of extensible and relatively non-extensible materials in the initial composite sheet. As previously stated, those components which, when combined into the initial sheet, form strong adhesive bonds, offer greater resistance to stretching and usually require greater amounts of stretch to obtain the desired vapor permeability. In such cases, the content of extensible or binder material in the initial composition may be. reduced somewhat in order to lessen the forces required for stretching.
• the initial sheet may contain minor proportions of various additives such as plasticizers, dyes, etc., plasticizers usually being incorporated with the extensible material.
• the improvement in the water vapor permeability of the initial composite sheets effected by stretching is directly related to the amount of elongation. At very low elongation, i. e., 510%, the sheets remain substantially impermeable even though they are stretched in two directions. However, as the amount of elongation is increased, the water vapor permeability increases; and the improvement is outstanding when the sheets are stretched in two directions.
• the nature of the extensible and relatively non-extensible material employed in the initial composition determines the amount of stretch required to effect the desired improvement in water vapor permeability.
• stretching in two directions that is, biaxially, appears to produce the greatest improvement in water vapor permeability for a given extent of stretch or elongation.
• the initial sheet should be stretched biaxially from 10-40%, the degree of stretching being substantially the same in each direction.
• the tensile strength of the present synthetic leather compositions decreases as the extent of stretch increases, the tensile modulus also decreases.
• a low modulus indicates a soft material; and this is usually desirable in a synthetic leather composition, es pecially for use in boots, shoes, gloves, etc.
• the degree of softness which may be imparted to these compositions by stretching is limited by the decrease in tensile strength which may be tolerated. From the foregoing, it is manifest that the present process is highly flexible; and the resulting synthetic leather compositions may be tailored to the desired end use by obtaining a balance between the desired vapor permeability and other physical properties, such as tensile strength, tear strength and tensile modulus.
• any desired expedient for stretching the initial sheet may be employed. Where the degree of adhesion between the extensible and relatively non-extensible material is high, drastic conditions of stretching may be required. So-called drastic conditions of stretching usually means soaking or conditioning the initial composite sheet in a hot liquid followed by stretching in one or both directions while the sheet is at an elevated temperature. On the other hand, mild stretching may be carried out by hand working, i. e., crumpling and/or flexing a sheet. Working the sheet by hand or mechanical means, however, does not always lead to producing uniform permeability throughout the entire sheet. In most cases, uniform permeability is only obtained by elongating the sheet in one direction and then in the opposite direction, or just in one direction, or by stretching the sheet simultaneously in both directions on a tentering frame.
• the initial composite sheet i. e., before stretching, must be substantially water vapor-impermeable.
• Initial composite sheets which are substantially permeable to water vapor i. e., have an LPV substantially greater than 1,000 grams/ 100 sq. meters/hr. (measured at 23 C. and 8l% relative humidity), are not normally convertible into a synthetic leather composition of satisfactory strength properties by following the present process.
• Initial composite sheets having a content of relatively extensible or binder polymer substantially less than 30% are considered to be within this classification; that is, the water vapor permeability of the initial sheet is high because the content of extensible or binder material is too low.
• any technique which will provide a composite sheet having particles or fibers of the relatively non-extensible material distributed uniformly throughout the relatively extensible material may be employed.
• the pressing temperature is usually above the flow temperature of the selected extensible or binder polymer.
• the water vapor permeability is low and it is not substantially greater than the water vapor permeability of a homogeneous sheet of either the binder material or the reinforcing material.
• a mat of intertangled fibers (the relatively non-extensible material) is thoroughly impregnated with the extensible or hinder material so that each individual fiber is surrounded by the impregnant.
• the fibers protrude through the surfaces of the sheet to provide for entrances and exits for the passage of vapor through the stretched sheet, the internal structure of the stretched sheet comprising a network of interconnecting pores or capillaries.
• a fibrous mat may be pressed into a film or sheet of the extensible or binder polymer.
• the pressing temperature must be above the flow temperature of the polymer.
• one sheet of the binder polymer- may be used, or the fibrous mat may be inserted between adjacent sheets.
• a fibrous mat may be impregnated by passing it through a solvent solution of the extensible or binder material.
• the solvent may be evolved by well known techniques.
• the binder or extensible material in the form of a powder may be distributed upon the surface of a moving fibrous mat, and thereafter the mat is subjected to a source of heat to melt the polymer and impregnate the mat.
• a source of heat may be employed, for example, infra-red, dielectric heat, heated rolls, hot plates, air oven, etc. This operation is followed by passing the sheet through pressing rolls to form a uniformly flat sheet.
• a moving fibrous web may be fed into the nip of a set of calendar rolls upon which the binder polymer is plasticated.
• the binder polymer and mat are fed between the nip, and the pressure of the rolls serves to impregnate the mat.
• a dispersion of particles or fibers (or a mixture thereof) of the binder or extensible material and particles or fibers of a relatively non-extensible material is prepared in aqueous medium or other inert liquid medium.
• This dispersion may be coagulated continuously to form a sheet consisting of a continuous matrix of the hinder or extensible material in which particles or fibers of the relatively non-extensible material are randomly dispersed throughout.
• the resulting sheet may be composited by subjecting it to light pressure by feeding between the nip of a pair of heated rolls.
• a fibrous mat may be passed through a liquid polymerizable organic compound to impregnate the mat with the polymerizable liquid. Thereafter, the impregnated mat is conducted through an oven or under a bank of infra-red lights to bring about polymerization of the liquid component.
• the liquid polymerizable organic compound should be thickened to a suitable viscosity, probably by dissolving a small amount of the hinder or extensible polymeric material in the cor responding liquid monomer.
• a continuously moving fibrous mat may be passed under a flamespraying apparatus which sprays uniformly the molten extensible or binder material onto one or both surfaces of the fibrous mat.
• This type of apparatus would have to be set up in such a way as to provide for complete impregnation of the mat.
• a hinder or extensible polymeric material in the form of a granular powder may be distributed onto a hot moving belt in order to sinter the particles together to form a continuous sheet.
• This sheet of binder or extensible polymer along with a fibrous mat may be fed into the nip of a set of pressing rolls to impregnate the fibrous mat with the binder or extensible polymer.
• a solvent solution or dispersion of the binder or extensible polymer may be continuously sprayed upon one or both the surfaces of a moving fibrous mat.
• the resulting impregnated mat may be passed thereafter into the bite of heated pressure rolls to compact the sheet.
• the binder or extensible material must melt or flow at a substantially lower temperature, usually at least 20 C. lower than the relatively non-extensible material in order to provide for compositing or compacting the combination of materials to form the initial sheet.
• compositions tabulated and. specified in Table 1 were prepared in accordance with the following general procedure: Crimped staple fibers of polyhexamethylene adipamide, 2 /2" long and 3 denier/filament, were carded to form non-woven mats or webs. The web was cut into sections and the various sections were put between screens and immersed into an aqueous solution of wetting agents containing 2% octyl sodium sulfosuccinate and 2% of a pared in the manner described above except Example 17 which was prepared by impregnating the non-woven mat with a benzene solution of polyisobutylene. After impregnation, the solvent was evolved and the impregnated mat was subjected to heat and pressure as mentioned above.
• the resulting substantially water vapor-impermeable composite sheets were then placed in a stretching apparatus and elongated a definite fraction of their original length or length and width, e. g., one-way or two-way stretching.
• the stretched sheets weer then subjected to various physical measurements, i. e., tenacity, elongation, modulus, tear strength and leather permeability (LPV).
• tenacity, elongation, modulus, tear strength and leather permeability (LPV) was measured at 23 C. and 81% relative humidity.
• neoprene BAG 0 53.5 733 .030 MD 4, 605 97 14, 631 9, 700 30 TD 496 1,27 7. 559 10,260 d0 1--------T----,- 30%.21) 52.5 709 .046 MD 2, 073 56.5 4,117 7, 510 5,000 TD 360 63. 75 2, 464
• TD 1, 292 191 1, 052 do 0 54. 4 777 .031 MD 5, 200 108 1, 598 11,000 375 TD 1,379 265 2,734 polyrsobutylena 30% 2D 827 060 MD 3, 597 112 2,095 12,500 4, 568
• TD 1 116 171 3,000 do 0 65 854 .040 MD 5,800 121 6,440 9, 500 45 TD 1 880 187 4,560 methyl acrylate., 40% 2D 55. 3 819 034 MD 7, 687 83 13, 100 6, 300 1, 633
• a dispersion or latex of the various extensible or hinder polymers indicated in Table 1 was prepared by various known techniques. Many of the latices are commercially available. After the webs were dried, they were then immersed in the dispersion or latex for a standard time, allowed to drain, and again put through the tworoll wringer. The polymer of the latex was thereafter immediately gelled by immersing the impregnated web into a 50% solution of acetic acid in methanol. The impregnated webs were then washed free of soap and acid with running water, and pressed free of excess water.
• the webs were dried at a temperature below 90 C. to prevent the polymeric binder from curing until the webs were placed between sheets of cellophane and Bristol board and pressed at 500 lbs. per sq. in. pressure and at a temperature above the flow temperature of the particular extensible or hinder polymer employed.
• Table 3 contains the results .of a test which may be employed for the purpose of selecting the most desirable combinations of extensible and relatively non-extensible materials from the adhesion standpoint. Assuming that the forces required to break the adhesive bonds are available, the ultimate limit would be the point at which the adhesion is greater than the breaking strength of the relatively non-extensible fiber. On the other hand, in the case of employing a relatively non-extensible material in the form of particles, the ultimate limit would be represented by a situation wherein the adhesion is greater than the breaking strength of the extensible material.
• the purpose of the adhesion test is to provide a method of selecting or screening various combinations of extensible and relatively nonextensible materials which exhibit little or no adhesion under the conditions required to composite the components to form the initial sheet.
• polyethylene does not adhere to nylon film under the conditions employed to form a composite sheet of nylon fibers impregnated with polyethylene, e. g., inserting a mat of intertangled nylon fibers between adjacent films of polyethylene and pressing the composite at 125 C. and 500 p. s. i.
• Table 3 also includes data on composite sheets fabricated from the materials tested.
• nylon fibers 2 /z in length and 3 denier/filament, were impregnated with the polymers indicated in Table 3.
• the method of preparing the initial composite sheet was the same as described hereinbefore except in the case of nylon fibers impregnated with polyethylene.
• the initial composite sheet in this case was formed by inserting a carded web of intertangled nylon fibers between adjacent films of polyethylene and then pressing the layers at 125 C. and 500 p. s. i. to form a composite sheet.
• Nylon polyhexamethylene adlpemide.
• Nylon N-methoxymethyl polyhexamethylene adipamide. 7 Mild Stretch (Hand Worked). 8 Swelled in hot water and stretched two ways 50% while hot.
• nylon polyhexamethylene adipamide
• the relatively non-extensible material may be in the form of particles.
• other types of natural and synthetic fibers may be employed such as other types of polyamides and interpolyamides, such as polyhexamethylene sebacamide, polycaproamide, and various interpolyamides as described and claimed in U. S. Patent No.
• polyethylene terephthalate polyacrylonitrile
• rayon and various natural fibers such as cotton and wool
• mixtures of two or more of the aforesaid fibers may be employed.
• Various polymeric materials may be employed as the relatively non-extensible materials in the form of particles of various sizes, such as particles of synthetic polyamides, and other synthetic linear thermoplastic materials.
• particles of thermosetting resins such as urea-formaldehyde, phenol-formaldehyde, etc., may be employed in particulate form.
• various inorganic materials may be employed in particle form such as titanium dioxide, zinc oxide, talc, clay and various diatomaceous earths.
• a mat of intertangled nylon fibers may be thoroughly impregnated with a latex of neoprene having an amount of zinc oxide particles dispersed therein (as much as 40% of the particles, based on total solids, may be used).
• the zinc oxide wise restricted except as set forth in the appended claims.
• a process for preparing permeable sheet material which comprises hot pressing fibrous material with a dry, thermoplastic, extensible polymeric binder material, said binder material being substantially more extensible than said fibrous material and having a flow temperature below the deformation temperature of the fibrous material and constituting from about 30% to about 70% by weight of the total weight of fibrous and binder materials, at a temperature above the flow temperature of the binder and below the deformation temperature of the fibrous material to form a substantially water vaporimpermeable compacted sheet and stretching said compacted sheet from about 10% to about 50% of its original dimension to form a water vapor-permeable, substantially liquid-resistant sheet.
• a process for preparing permeable sheet material which comprises hot pressing a non-woven mat of fibers with a dry, thermoplastic, extensible, polymeric binder material, said binder material being substantially more extensible than the fibers and having a fiow temperature below the deformation temperature of the fibers and constituting from about 30% to about 70% by weight of the total weight of fibers and binder, at a temperature above the fiow temperature of the binder and below the deformation temperature of the fibers to form a substantially water vapor-impermeable compacted sheet and stretching said compacted sheet from about 10% to about 50% of its original dimension to form a water vaporpermeable, substantially liquid-resistant sheet.

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• Engineering & Computer Science (AREA)
• Textile Engineering (AREA)
• Chemical & Material Sciences (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Dispersion Chemistry (AREA)
• General Chemical & Material Sciences (AREA)
• Synthetic Leather, Interior Materials Or Flexible Sheet Materials (AREA)
• Nonwoven Fabrics (AREA)
• Chemical Or Physical Treatment Of Fibers (AREA)
• Catalysts (AREA)
• Laminated Bodies (AREA)

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Cited By (13)

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Citations (18)

• 0
  • BE BE523941D patent/BE523941A/xx unknown
• 1952
  • 1952-11-04 US US318732A patent/US2757100A/en not_active Expired - Lifetime
• 1953
  • 1953-09-09 GB GB24943/53A patent/GB763604A/en not_active Expired
  • 1953-09-21 FR FR1090575D patent/FR1090575A/fr not_active Expired
  • 1953-10-19 DE DEP10650A patent/DE1010945B/de active Pending

Patent Citations (18)

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