CA1052196A - Water vapour permeable sheet material - Google Patents

Abstract

ABSTRACT
There is disclosed a water vapour permeable shoe upper material having at least three layers, the density, thickness and structure of the layers having a defined novel relationship whereby an improved cut tear to stiffness relationship is achieved.

Description

~h~ E).~esent lnventi.on relate3 ~o ~Jater v~.pou.r permeabJ.e sheet,material.s~ ~uch rnaterials fi~d many u~es a~d i.Il particular find use as shoe upper materials and clothing materials~ , ~n excellcllt mi.cxoporous polyu.rethane sheet ' ; material which is free from pxe-fo~med fibrous ~' rei~orcement and which consists'of a micropo.,ous strength impar-ti~g substrate layer about 1~35 mm. , ' ~'' thick having a cle~sity of about 0.55 grams per s~axe ,, ~ , , metre and ha~ing in-tegrally attached to o~e ~ace a ; ~, thinner less dense surface layer is alread~ known. , .. ' ~ ~he surface layer is tgpic,ally a~out 0.35 mm. thick ~, , and has a de~sity of about 0.35 grams per cc. q'he ~ :
: ~' free surface of the surface layex is give~ a very ,.~
15~ thin surface finish. . ~' ?
his-material has a gaod cut tear stre~gth ',' ",:
for fabrleation into shoes and an ade4uate ~ater , ,' vapour pexmeabilit~ prior to fi.nishi~g so that after appllcatlon o~ the fi~ishi~g the p~oduct still has a , '~ ' .
20~ su~floient,water vapour permeability for use in shoe~uppers. However, for cereain uses the product ,.. '~.
; is somewhat stiffo ~he stiffness of such a materiaI ."
could be rèduced b~ xeducing the thickness of the strength impaxting substrate but we have found tha~
:25 ~this results i~ a product havl~g~inade~uate tear strength and.in additioQ a product below 1.5 mm, thick has~ ade~uate ~substance fox commerc:ial u,se as : :a~men'~s shoa uppera Thus in these k~own materials the ratio of cut ';~ ;
30 tear stxength to stif~ness (as de~ined herein) is ,~

', K~NK/Sd~R
~ ~ 1.':- , '"

- 1~5~196 usu~ .y about 2 to 3.4.
W~ have discovered that by reducin~ the thi.ckness of the substjrate :Layer and at the same ti~nc givin~ it a stronger structure and by formin~
a ~ur-ther suxface layer (whlch will be termed herein the flesh layer~, on the face o~ the substrate remote from the topcoat layer substantial reduction i~ stiffness can be ach.ieved whilst , maintaining ade~uate tear strength and water vapour per~eability and product thickness.
It is thus a~ object o~ the present invention to produce water vapour permeable materials free ' ~ from ~ibrous reinforcement having ratios of cut tear stre~gth to stiffness in excess of 4 and 15 desirably in excess of 5~ -~ , U.S. Patent 3284274 discloses that in making manmade suedes and smooth surface leather-like .
materials for shoe uppers a layer o:~ cellular honey-comb like macroporous polymer material may be applied to both sides of a flexible porous substrate which can be a~sheet of non-fibrous porous pol~meric .
material such as a tough microporous filmc We have found that unless the su~strate is made both denser a~d thicker than either the fleshcoat ~layer or the topcoat layer the desirable improvement . ~ ;~
in the ratio of cut tear strength to stiffness is ~
not obtained. .;-hus according to the prèsent inventio~ a water vapour permeable so~t flexible sheet material .;:~1 I ~ ~ 30 suitable for use as the upper o~ a sh~e ;.n place o~ `~
', , , -KDI~/SdeR
. :
:, 1 5~ 9 ~

lea-ther is at lea~t 0.8 mmO e.g., 1.0 - 2.0 ox 009 -l.rf ~ thick and has at 1ea~Jt three superimposed ' pOXOllS layers of elastomeric polymer the material being ~xee ~rom fibxous re:in~orcement and havlng ~n 5. elo~gation at break in excess of 200~o a~d comprises a strength imparting poxous elastomexic polymer sub-strate layex ~po~d between a porous elastomeri¢
polymer ~leshcoat layer and a porous elastomeric poly-mer topcoat la~er9 the substra-t~ laye~ having a higher 10. de~si-ty than the ~leshcoat ox topcoat layers a~d being thicke.r than either the ~leshcoat or the topcoat layers and the combi~ed thick~ess o~ the fleshcoat and the topcoat la~ers being in the range 30% to 175%
, . .
o~ the thickness o~ the su~stxate layer, e.g., 65to ~;
15~ to 125% especially 70% to 110% Of the thickness o~
the substrate layer a~d desirabl~ the thic~ess o~
~ th~ topcoat layer being in the range 150% to 50% o~
;~ the thickness of the ~leshcoat layer. ~he thickness o~the ~opcoat ma~ be in th~ range 10% to 95% e~g. 30~ -~ ~ . :- .
20. to 80% o~ the ~hick~ess o~ the substrate. ~he flesh~
coat may be in the range 10~ o~ 20~o -tO 95~o o~ the ~ , . . .
thick~eæs of the s~bstrata, ~h~ ratio o~ the thick~ess o~ -the topcoa-t to the ;~
." . "
thickness o~ the substxate desirably lie~ ~ithin the `~
25. range l~5:1 to 0.5~1 more particularly 1.2:1 to 0,8:1 .
a~d iæ pre~erably about 1:1, thuæ the material is ~ -su~stantially symmetrical about the plane through the ... . .
centxe o~ the inner (~ubstrate) layer~
In a pxsfe.rred foxm o~ -the inve~tion ~he strength 30. imparting porous elastomeric polymer substrate layex ' KDNK/~RC - 4 -.~.. .... . . . .

~05'~

has compact voids randomly distributecl through the layer intercommunicating via pores penetrating the walls be-tween the voids, and the fleshcoat layer is microporous having compact voids randomly distributed through the layer intercommunicating via pores penetrating the walls between the voids, and the topcoat layer is microporous having compact voids randomly distributed through the layer intercommunicating via pores pene*rating the walls between the voids, and the substrate is characterised by having wall thicknesses between the voids generally greater than those in the fleshcoat or the topcoat.
The inven~ion enables preferred materials to be made which are further characterised by having a cut tear strength (as defined herein) of at least 1.5, e.g., at least 2.3 kg. and a ratio of cut tear strength to stiff-~ness Cas defined herein) of at least 4.2, e.g., in the range 5.0 to 10.5 or preferably 6 to 10 and a stiffness ;~
, (as herein defined) of not more than 0.65 and preferable in the range 0.25 to 0.60, e.g., 0.30 to 0.50.
According to a preferred form of the present in- ; ~ ~
vention the substrate layer consists of a porous matrix of ~ -elastomeric polymer affording a plurality of compact voids intercommunicating by pores, the said substrate layer , being from 0.5 to 1.2., or 1.5 e.g., 0.6 to 1.0 mm pre-ferably 0.7 to 0.9 mm thick and having a total void volume or porosity in excess of 50% and at least 65% of the poro-sity being provided by pores and the voids with which the said pores interconnect, the said pores having diameters of at least 5.0 microns and preferably less than 20 microns `
as determined by mercury intrusion penetrometry. T~e mean pore diameter of the substrate : :

~'' ' ' -- . : ,:
, ~ , ,. .

~ ~5~ 19 ~
layer is pre~erably in the range 5 to 20 m~cro~s~ preferably 7 to 15 microns, e.g., lO
to 12 microns as de-termlned by mercury intrusion penetrome-tr~.
~`he fleshcoat and topcoat layers are ~ -preferably integrally adhered -to the substrate layer.
~he fleshcoat and topcoat layers preferably have thicknesses in the range 0.20 to 0.45 mm. ~he top-coat la~er and the ~leshcoat layer desirably have densities of less than 0O40 grams per cc., e.g., in the range 0.2 to 0. 4 9 e.g., Oa 25 to Q.35O
~he elastomeric polymer is preferably a~ `-elastomeric polyurethane hut can be used i~ admixture with other thermoplastic polymers such as polyvinyl -chloride and its co-pol~mers and acr~lonitrile pol~mers and co polymers ~he preferred polyurethane polymers are essentially linear polyurethanes produced ~rom a diisocyanate, a monomeric diol and a polyester or a - 20 polye-ther o~ molecular weight l,000 to 3,000, the ~ `
polyurethane having a~ i~trinsic viscosity in .~ , .
dimethyl formamide of at least 0.8 ~ /g.
However, the preferred polymer is a polyester based pol~urethane materiaI having a Shore hardness

- 2', of 75A or 90~ to 60D preferably at least 98A as a soli~ continuous sheet at 25C. ~his material may be used for all three layers. Eowever, in a pre~erred product it is used only for the strength imparting substrate la~er and a pol~urethane having a lower ~0 Shore hardness than -the substrate polyurethane and KDNK/~deR

., .~ .

9 ~
thus a ~ofter feel i.s used for the topcoat layer and. the flesh layer. ~his softer material may have a nitrogen content of about 2.5/o or Z.8 to 3.0 or

3.5 to 4~0~0n ~his soft material can be made b~
increasi~g the ratio of polyester to glycol result.ing in a lower re~uirement o~ diisocyanateO
The polyurethane for the substrate preferably has a higher nitrogen co~te~t, e.g., at least 4.~/o or 405% or moren ~he soft polyurethane for the top~
coat la~er and the flesh layer may be based on a polyether polyur~thane instead of a pol~ester -~
polyurethane.
In one form of the in~ention~ the polyurethanes .
used for the topcoat, fleshcoat ~ld substxate are made ~rom the same polyester~ diol and diisocyanate a~d the polyurethane used for the substrate has a - nitrogen content o~ at least 4~o whilst the polyure~
thanes used for the topcoat and fleshcoat have lower ~`~ nitro~en conte~ts than the substrate polyurethane. ~-~he subs~rate layer preferabl~ has a porosity in the range 5~0 to 65% and less than 7% of -the total porosity is provided b~ pores and -the voids with which `
they interconnect the said pores ha~ing diameters in excess of 100 mi.crons and at least 50~ of the total -~ `
~ . .
pGrosity is provided by pores a~d the voids with which they interconnect the said pores having - , diameters in the ran~e 6.4 to 17.5 microns~
;, he substrate layer when a cut cross-section is ` `-viewed is preferably further characterised b~ compact voids the ma~ority of which ha~e maximum dime~sions KDNK~deR

:~ .

in the plane of the cross-section of 30 to 100 microns, the majority of these voi.ds having shortest transverse dimensions i~ the plane of the cut surface of 1/~ their maximum dimension and above, the shapes of the ~oids being non-spherical and though i..rregular in outline compact in shape, the voids being separated by more dense regions ~which can be considered as thicker walls~
~-:
- . . which contain smaller pores visible at 150-fold magni~ication the majority of which are 1 to 30 micro~s across and spaced apart by 1 to 10 microns -the majority of these denser regions being of 30 to 100 microns across between adjacent`larger voids~
~he microporous ~leshcoat and topcoat layers 15 when a cut cxoss-section i9 viewed are preferably :
charac~erised by irregular shaped through compact voids from 5 to 75 microns across the majority -~ `
being 20 to 50 microns across the ~aid voids being def:ined or surrounded b~ thin walls 1 to 5 microns /`~;
thick the voids intercommunicating by pores passing through these thin walls~
: ~ ~he ~ovel product may be made by a process ` comprising depositing a layer o~ coagulable -elastomeric pol~mer Pleshcoat composition on a porous support to form the fleshcoàt layer, then prior-to coagulation depositing a layer o~ coagulable ~:`
elastomeric polymer substrate composition on top of the layer o~ ~leshcoat composition and then prior to ` ~ ~ `
ooagulation depositing a layer of coagulable elastomeric t~ coat co~position on top of the layer KDNE/SdeR

-,' 1~5'~
of subs~rate composition, and then coagulating the composite material to an integrally adhered microporous three~layer structure free from fibrous rein~orcement at least the substrate com- ;
position an~ at least one o~ the flesbcoat or top-coat compositions containing a removable particulate filler, the filler in the said fleshcoat or topcoat compositi~ns having an average particle size smaller than that used in the substrate composition.
lU~he elastomeric polymers are pre~erably elastomeric polyurethanes of intrjnsic viscosity o~ at least 0.8 e.g.9 1.0 to 2.0 or 1.0 to 1.~ decilitre~/g.
{measured i~ dilute solution in dimethylform~mide). -~he polyurethanes of the fleshcoat and topcoat layers 15 are desirabl~ so~ter than that of the substrate layer, ` ; ~`;
e.g., the substrate po}ymer as a th m void free film ~ 0.2 to 0~4-~mm. thick may have a modulus at 25%
-~ ex*ension of at least 55 kg/cm2, e.g., 60 to 100 or 70 to 80 a~d the ~leshcoat and topcoat polymers as a thin void free film 0.2 to 0.4 mm. thick ma~ ha~ a modulus at 25% extension of less than 55 kgO/cm2, - -~
- e.g., 30 to 45 or 50 kg/cm2.
~he ~ubstrate composition preferably comprises ,, , ~. .
the substrate polyurethane dissolved in a polar organic sol~ent, e.g., dimeth~lfo~mamide, at at least 20~o b~ weight concentration, eOgo ~ 25% to 4~/q e.g.1 30% to 35% with a~particulate dissol~able filler, e.g., a water soluble inorganic salt dis-persed therethrough, which is substantially insoluble 30 in the organic solyent, &nd the filler has an average ~; -~ 9 ~ -~ K~NK/SdeR -~ -.,,. ~ 1~ ~.
' ~

~3~ LC~6 particle size as determined by Coulter counter measurements in the range 20 to 200 microns~ e.g.
25 to 75 or 50 microns and the ratio of filler to polymer is in the range 1.8 : 1 to 2.7 : 1, e.g., ~
1.9 : 1 to 2.2 : 1 parts by weight. More particu- ~ -larly it is preferred to use a particle size of ~ ;~
30 to 95 microns with a filler to polymer ratio in ~ ;
the range 1.8 : 1 to 2.8 : 1 at the 30 micron salt -particle size and in the range 1.8 : 1 to`4.0 : 1 at about the 95 micron particle size.
As taught in the specifieation of British Patent No. 1465,557 working in this range produces a material of improved strength. Attention is particularly directed to its teaching as to the preferred formulations for a substrate for an artificial lea1her and the disclosure concerning preferred filler particle sizes. It is pre~
ferred to miake use of this teaching in connection with the substrate for the present in~entionO ~ ~;
The flesh and topcoat compositions similarly contain dispersed filler but it is pre-ferred that the filler should have an average part~
icle size below 20 microns, eOgO~ in the range 1 to 15 .~ - .
. . .
or 5 to 10 microns. The ratio of filler to polymer is -~
preferably at least 2.5 : 1, eOgO~ in the range 3 : 1 to 6 : 1 parts by weightO ~ ~ ~

' ~ ~''` ' ~L05'~g~;

The polymer composition is preferably pro- ~
duced by forming the polymer in solution from low mole- ;
cular weight reactants in solution to produce a polymer solution of the desired concentration and then mixing the particulate filler (which is prefer-ably wa~er soluble) into the polymer solution, e.g., with a high energy mixer. The blend is then co-agulated to self-supporting form by means of a non-solvent liquid, e.g., it is preferably extruded on- ~
to a porous belt and contacted with non~solvent, e.g., water ~e.g., at 20C. - 60C.) or water solvent blends~ er~g.l of 5% to 30%~solvent content, having a non-solvent action, e.g., by immersion in the liquid non-solvent. The non-solvents used can contain ~ -~
proportions of dissolved filler, e.g., in continuous operation contents of as high as 15% or so of filler can be tolerated. Pure non-solvents are equally ~;
;: `:
effective.
The coagulated self-supporting layer is then preferably stripped from the belt whilst wet and immersed in non-solvent, e.g., heated to, say, 60C., and the dissolvable filler leached out ~o a ''`, .'~,'. .;, ' ~

.~'`-~ .
" , ' . ~' " ' ~ ~5~ ~9 6 sa-~isfa.cto.ry level, e.g., not mo.re than 1,000 mg. ~ ~
of filler per s~uare metre of sheet should remain. ~ ;
The leached. layer is then dried and can be given c~ny appropriate finishing operation.
5. ~he preferxed density of the substrate layer of :the product is betwee~ 0.4 and 0.7 gr. per cc.
;:
thollgh it ma~ be up to 0.8 for cextain uses. .
: It is pre~erred to use flller particle sizes and filler to pol~mer ratios such that the density I lOo of the substrate layer remains within the range 0/4 to 0O5 or 0055O ~h~s with the lower end. of the ran~e o~ permi-t-ted particle sizes the lower end of -:
the permi.tted range o.~ ratios of filler to polymer ~

~ .

: - . . . .-.. ~.. ..

- '.. ' ~ , .

` :
KD~/SdeR -12~

, ' ~ ~ ! , . . , , , ' , . . .

5~

is preferably used and at the hi.gher end of the range o~ particle sizes the higher end of the xange of ratios of fi.ller to polymer is pre~er-abl~ used, e.g., with a~erage particle sizes of 20 to 30 microns the filler ra-tio is preferably 1.9 : 1 to 2.1 : 1 with ~0 to 60 micron filler f.rom 2~1 : 1 to 2.2 : 1, 2.3 : 1 or 2.4 : 1 and with filler paxt.icle sizes above 60 microns salt ratios of abo~e 2.2 : 1 or 2~ 4 : 1 ~he invention may be put into pract.ice i~
; various wa~s and certain specific embodime~nts will be described by wa~ of example with reference to the accompan~lng photomicrographs which are all vertical cross-sections through microporous sheet materials at 55-fold magnification and in which:
~i~ures 1 to 8 are of three~layer materials `~
in accordance wi~h the invention described in ~Examples 1 to 8 respecti~e, and ~-Figure 9 is a diagrammatic side elevation. o~
a test rig use~ for determining the stiffness of ma~erials described hereiu.
~'he photomicrographs of Figures 1 to 8 were ~, ~
;~ taken on a Cambridge Instxuments ~imited.
Stereoscan Mark 2 electron microscope. ~he ; ~ 25 photomicrographs were prepaxed ~y cutting a smooth ~`
clean cross-section through the sheet samplesO
~` ~he cut surface was then coated with a thin metallic, e.gO, gold or palladium reflecting layer as is con~
ventional in preparing samples ~or electron photo- ~ -mi~rograph~. A stream of electrons was then directed : . ; ~-,:~:, - 13 - ;
KD~KfSaeR
, , .'.' :~' 5'~1~3 onto the cut surface at 45C. and the electrons reflected ~rom the surXace also at 45C. were colLected and used to produce an optical image ~;
which was photographed~ It will be apprecia~ea that the depth oP focus of such photographs is ~ ~ ~
very much ~reater than i~ optical photography and ~ ~ -thus that in e~ect one is able to see into the voids and cavities~
~ ;:"
In the examples a vaxiet~ oX polyurethane pol~mers are used~ ~hey were made in solution in dimethy1formamide :~rom a polyester or polyether by ~^
reaction with a diol and a diisocyanate under an inert atmosphere.
rethane~
880 parts (I~ o~ pure N,N-dimeth~lformamide . `;
uere placed in a 1,500 parts (II) reactor ~lushed with dry nitrogen. 0.027 parts ~I~) of paratolue~e sulphonic acid a~d 0.020 parts (23 oI dibu~yltin dilaurate were dissol~ed in the dimeth~l~o~amideO
205.0 parts (III) o~ Desmophen~2001 polyester ~a~
hydroxyl-terminated pol~estex o~ 2,000 molecular ~5~`
weight, ha~ing an acid number of less than 2 and a hydro~yl number of about 55 mgO KQH~per g~ made from about 1~m~1 butane diol -1,4,;1~12 mol ~; 25 ethylene gl~col and 2 mols adipic acid) and 48 parta~(IV~ of butane diol -1,4 were then~added and d1ssolved i~ the mixture a~d the temperature o~ the I
mixture adjusted to 25C.
171.6 parts (~) o~ 4,4-diphen~lmethanediiso-~;; ; 30 cyanate were then added bit by bit care being taken D~SaeR~ -~trade~ ~)7qrk . ..
:~, ~ ' , 1,, ~ `.
, : , .
.

05~

to keep the temperature from rising above 50C.
Once the addition was complete the mixture was heated to 60C. and maintained at that tempera-ture for 1-~ hours with stirring. ~he excess unreacted isocyanate content ~as then determined ' , by titration of an ali~uo to Su~ficient butane diol ~3.0 parts (VI~) was then added to react ' ~ ~, esse~tially stoichiometrically with the unreacted isoc~anate. ~he mixture was then maintained at 60Q. with stirring'and the viscosity measured periodically unti] it had risen to a value of ~ -about 3,500 poise (Brookfield 5 or 6 spindle) as ;, corrected to 24C. 4010 parts (VII) of butane `;, - diol 1,4 were then added as capping agent to ; 15 terminate the I~eactio~ dissolved in 3.5 parts ~VIII) ~' of N7N-dimethyl~ormam'ide. '' ,~, .
~~he nitrogen content was about 4~5Yo and the `',~
., polyester con~ent about 50YO~ The pol~urethane had I ~ a Shore hardness of 55D as a solid continuous sheet " ;~
~, ~ 20 at 25C
he polyurethane has the following physical properties~
,, ~he solution has-a viscosity of 4,100 poise at ` ~ 330~/o solids at 24C. (Brook~ield RV~ No. 7 spindle 2.5'rpm); an intrinsic viscosity of 1.08 decilitre/ , '~
gram;`''and a k' of 0.60~ A void free film cast from th~solution by slow e~raporation of the solvent has ,',~
a tensile,modulus (kg/cm2) at 5%, 25yo~ 50Yo and lO~o elongation of 2703, 74.5, 95~8 and 120 respectively;
a tenslle strength (kg~cm2) of 589; an elongation a-t ~DN~SdeR ' ''~
.

~ ~:

the crystalline point of 48~XJ and at br~ak of 615%; a cut tear strength of 180 kg/cm and a tear strength to 25% modulu~ ratio of 2.4. ;;;.
~ hane 2 : ~.
~his is made in the same way as Polyurethane 1 ~ -.
but the amounts of the reactants are varied. .~ ~.
DM~ is 900 parts, paratoluene sulphonic acid (IX) is 0.06 parts, . ~. -dibu~yltin di.laurate (X) is 0.027 parts, ;~
Desmophen 2001 .
polyester (IIX) is ?82~4 parts, .
butane diol (IV) is 30.0 parts,

4,4'-diphenylmethanediisocyanate (V) is 132.6 parts~
butane diol (VI) is 5 parts, ..
butane diol ~VII) is 5 parts, and `. ~`~
DMF (VII:[) is 100 parts-.
~ his gives a polymer with 3.3yO nitrogen -~ ~ co~tent ~he solution has a visooslty at 33.2% solids "~
at 24C~`of 4,100 poise; an intrinsic viscosity of i . -1.145; a k' of 0~48. A film cast from the solution as for polyu-rethane 1 has a tensile modulus (kg/cm2) , ~
. at 10~o7 25% and 50~o of 23.5, 37O9 and 49.6 respec~
: 25 tively; a tensile strength (kg/cm2) of 465; an .. .
; elongation at the-crystalline point of 620 at break ..
of 710%; a cut tear strength of 113 kg/cm and a - tear strength to 25Yo modulus ratio o~ 2.98. x~
ne 3 ~his is made in the same way as pol~ure~hane 1 KDi~/SdeR

: ~
~ .
- 1, ~ 05'~
but the clmOUnt. of the reactants ~re varied and Bayer polyester Desmophen trial product I~ 1816 ~ ;
is us~d i.nstead of Desmophen 20010 PU 1816 is a hyaroxyl texminated polyeste~r of 2,250 molec~lar weight, having an acid number of less than 2 and a hydroxyl nu~her of 50 ~2 mgO KOH per gram and is similar to Desmophen 2001 apart from its diol compo~en-t.
DMF (I) is 900 parts, paratoluene sulphonic acid (I~) i.s 0.06 parts, dibutyltin dilaurate (~) is 0.027 parts, ~ ~-i - . ~.
polyester PU 1816 (Il:I) is 271.3 parts, buta:ne aiOl (IV) is- 3~.0 parts, 4,4'-diphenylmethanediisoc~anate ~V) is ~ -140.6 parts, butane di.ol ~I) is 5.1 parts, butalle diol (VII) is 5.0 parts, and ~! ~ DM~ (VIII) ls 100 parts.
.. . . ..
hie gives a polymer with a 3.5Yo nitrogen 20 contenl.~ -~
- ~he solution has a viscosity at 33~2~o solids -at 24C~ o~ 3~400 poise; an intrinsic viscosit~ of 1.11; a~d a k' of 0~49 A film cast from the solutio~ as for polyurethane 1 has a tensile ~` ~ 25 modulus (kg/cm2) at 10/o~ 25% and 50% of 19~0, .
36vO and 4~.2 respectivel~; a tensile strength i " (kg/cm2) of 519; an elongation at the crystalline ;
~ ~ point o~ 560'~o and at bxeal~ o~ 61~0~o; a cut tear ; ~ ~ strength Of 143 k~/cm and a tear strength to ~5%
:
:` 30 modulus ratio of 3~98~ ` `;

KDN~/Sde~
,-.
..

. . .

5~JI9~; ', ~o~4 ~his i5 made in the same way as polyurethane 1 .;
except that the dibutyl-tindilaurate catal~rst, - .-component (X), is omltted~ ~he reacta~ts are as , : -5 follows~
. ,: . .
DMF (I) 900~.00 parts Paratoluene sulphonic acid (IX) 0.06 parts Polymeg 1930 polyether (~.II) 254.20 parts .
Butane d.iol (IV) 38.30 parts `-.
lO 4,4'-di.phenylmethanediiæocyanate 152.70 parts Buta~e diol (Vl) 3O~0 parts Butane diol ~VII~ 5.00 parts . ~.
DM~' ~VIII) 20.00 parts ~ .
~hls gives a polymer with a 3~8Yo nitroge~
15 content, .Polymeg 19~0 is a hydro~yl terminated , poly-tetramethyle~e glycol havi~lg a molecular `.
weigh-t of 1930, a hydro}~yl number of 53 to 59 and a very low aci.d numbe.r not in excess of 0.05 mg.
KOH per gram~ It has a meltirLg point of 38C. and ..
: 20 : a specific gravity of 00985 grams per cc at 25C.
q!he pol~mer solution has a viscosity at 33.2%
solids at 24C. o~ 4,400 poise; arL intrillsic viscosity of 0.88 dl/g; and a k' of 0065. A film oast from the solution as for pol~urethane l had a teIlsile modulus (kgfcm2~ at 5%, 25%~ 50% and 100%
exte~sion of 9.~, 37.4, 50.8 and 66.9 respeGtively;
- a tensile stren&~th (kg/cm2~ of 447; an elongation at the cr;ystalli~e` point of 680/~ and at brea~ o~
: ~- ~ .. .
715Jo~ a cut tear strength of 95.8 kg~cm and a tear ; ~ 30 strength to 25% modulus ratio of 2.55. :

KD:NK~SdeP.
tr~cle.

:, ... :
~; .

'.rhe Remov~b].e Filler . . ~
Sodil~n chlo.ride ~or incleed other e~uivalent preferc~ly wate.r soluble removable filler) ~jas ground in a pin and disc mill with air clas~
cation to separate out fines and return oversi~e particlcs for regrinding. ~he sodium chloride powder befoxe dispersing in the polymer solution had its particle size determined by the Coulter counter techni~ue. . ~ ~
~ou~.ter counter measurement of particle size .~ -is a well known techni~ue and is widely used and ; described in th~ literature, for example, in the ~ :
book 'q'he Coulter Principle of Particle Size :
Measu.rement' by To Allen and K~ Marshall~ available :
in the National Library o~ Science and Intention (Patent Office Branch) in ~ondon~
However, a brie~ description of the techni~ue will now be given. The sodium chloride whose . .
. particle size is to be measured is suspended as a - ~-~
~ery dilute suspension in a saturated 4% solution ~; o~ ammouium thiocyanate in isopropanol which is previousl~ saturated with sodium chloride.
~he mixture is subaected to ultrasonic vibration to ensure that none of the particles have ~ 25 agglomeratedr .. ?he suspension is the~ plaeed i~ the measuring ~ :
` chamber OL -the apparatus which is descxibed i~ U.SO - :.
Patent 265650~. An electrode is placed in the .. .. ~-; ~ chamberO A tube containing another electrode and .

19 - .
; KD~/BdeR

. 1~5~ 6 having a ve~y small orifice appropriate to the paxticle size is i.mmersed irL the suspension which is then drawn through the tube~ For salt of 9 to 126 microns a~erage particle si~e a tubs having - .
an orifice of 280 microrLs is used. ~ach ~ime a particle passes through the orifice a vol-tage pulse ~ ;
propoxtional to p~rticle volume is produced, the larger the pulse the larger is the particle ;~
The electronic circuit of the irLstrument can -. ;
10 be arranged so as to count only pulses having a .
.volume withi~ a certairL range and the number of pulses withi~L a given time within each range is counted ~or a series o~ ranges. ~he results are : therl ad~usted to give a distribution of particle - ~
siz~ by weight.
~he concentration of the particles in the sample . is arran~ed to be below the so-called 'coincidence .
leve!l', namel~, the concentratioxL at which the proba~
bili.ty o~ more than oxLe particle passing ~rough the . :
- : 20 orifice at the same time and being counted as a single .. ~ part;icle becomes si~Li~icant, ~hus ~or salt o~
OEticle size about lO microns a 0.05 to 0.1% b~
: wei~h~ suspension is used, for about 50 mi~rons O.l to :
: 0.3% by weight is used ana ~or about 90 microns, about 0.3 to 0.5~o b~ weight is used.
AIl:the values o~ avexage particle size given i~
the spe~ification re.~er to measurement with a Coulter ~ ~ .
~ , : counter industrial model ZB with a volume converter : model M2 using a tube with an orifice o~ 280 microns : 30 except in co~nectio~ with ~able 30 KD~/Sde~
.
j ~
, - : - , . ~: .

I ~ :

~05;2~L9~

~ or any given average particle size the negative deviation value is the particle size below which only 16% by weight of the to~al mass is located and the positive deviation value is the 5. particle size above which only 16% by weight of the ;;
total mass is located~ q'he positive and negative deviations from the average do not have to be e~ual.
~he average particle size is the size at which 50%
by weight ~alls on either side of the ~alue give~.
IO. q~us at least 84~o b~ weight of the filler desirably has a particle size of at least 10, 15 or 30 microns and at least 68% by weight has a particle size in the range 15 to 100 or 25 to 75 microns and especiall~ 30 to 70 microns. `~
15. Desirabl~ also the posltive and nègative deviations~are less than 50/o, e.g.) in the range up to 45%, e.g~, 30 to ~5YoO
~ : , .
~.
.: i ,. .
. . ~: : : ,.i ' i ' '; . . , . - ~

.. .. .
i-: :.
.: :
: i ~ ::
i . , , " ;,. . .. .

~ KD~K/5deR -21~ ~ ~
.. ..
-. : : ,; , ~' , - . . . .: .. . . .. . .

1~5'~ ~L96 Exa~le 1 ~ hi~ is an example of a three-layer product in accordance with the inventio~0 ~ he substrate 15 has a coarser pore structure than the topcoat 16 and fleshcoat 17 which are made fxom a so~ter polymer (polyurethane 2 described above~ than the substrate.
_ ~he method used to ~orm the composite adhered -~
layers is as ~ollows:
A ~leshcoat paste is doctor knife spread first ~ ;.
onto a porous polyethylene sheet, a substrate paste .
is the~ spread over the layer of ~leshcoat paste a~d ; ~ ;
a topcoab paste æ -then spread over the substxate paste. ~he adhered superposed layers o~ pastes on the porous support are then immersed in pure stationar~ water (water solvent salt blends are e~ually e~ective) at ~0C. for~l hour with the coated face downwards to coagulate the pol~mer i~
the pas~e to self-supportiug ~orm. ~he composite three-layer material i6 then stripped from the support without rupturing a~d immersed in stationary water at 60C. for 5 hours to substa~tially completely remove the DM~ and reduce the sodium-c~loride content to a very low level, i.e.~ well `~
below 1000 mg/s~. metre, so as to give accurate de~sity measuremen~s.
~he material is the~ dried at about 70C. in an air oven for about 2 hours. Its propertles are gi~en in ~able 1 below.
30 ~ ~he substrate paste 1 is made by mixing and ~K/SdeR `~

. .
::

~ 5 ~
milling ~he polyurethane solution descrlbed above as pol~urethane l (diluted to 3~J0 resin concentra- ~-tio~) with 1.90 parts per part of polyurethane of sodium chloride particles havin~ an average particle siæe of 27 microns (negative deviation 12 microns;
positive deviation 21 microns) followed b~
de-airing under ~acuum.
_ ~he topcoat and fleshcoat paste l ls made with the polgurethane solution described above as polyuretha~e 2 (diluted to 25% resin concentration) mixed and milled with 3 parts per part o~ polyure- `
thane of sodlum chloride particles havin~ an a~erage particle size o~ 9 micxons ~negative deviation -3 microns; positive deviatio~ +4 microns) followed by 15 de-airing under vacuum. - -The properties of the material are given in able l. -A single layer material made ~rom the same paste as substrate paste l and in the same manner but at a considerably increased thickness ~1.4 mm.) has its p~operties listed in ~able 3 and the results of mercury intrusion pènetrometry listed in ~able 4 This is ~n example of a three-layer product similar to Example l but having a ~hicker substrate 18 of less coarse st~ucture.
he material is made in the same wa~ as Example l~ the only dîfferences being the use o~

_ 23 ~ -RD~R/SaeR
:

~ 96 sodiu~ chloride having an average particle size of ll~ microns (ne~ative deviation 6 micron~;
positive de~iation 15 microns) in the substrate paste.
~he properties of the materi~l are given in ~able l.
A single layer material made from substrate - paste at the same thickness had a densit~ of 0~56.
- ~
This is an example of a three-layer product similar to Ex&mple 1 but having & di~ferent polymer - in the topcoat and fle~shcoat layers.
~he method and formulations are the same as for E~ample 1, the o~l~ dif~e~ence bein~ that the ;
; ~ 15 polyurethaIle solution desc~ibed above as polyure~
thane 3 is used in the M eshcoat and topcoat la~ers ~ ;~
and the la~ers are of different thicknesses.
~he properties of the material are given i~
~able l.
0 ~
~his is an eæample o~ a three-layer material - similar to Example l but having a different polymer, ~:~~ namely, polyurethane 3, described above, in the ~ -~
. . . ~
~, ~ topcoat a~d fleshcoat pastes. ~lso the substra~e paste is made with coarser sodium chloriae of average particle size 31 microns (negative deviation 12.5 microns; positive de~iation 18 ~ miCxons? and with 2.0 parts o~ salt per part of `~
polymer. Apaxt from-~his the method and `~
; 30 for~ulations are as in E~ample l. ;~

~DNK/SdeR
, 1 :
"",i,.,,,'" ~, ~" ~ ,,", "~ " ~ "'~ "

The properties of the mateIial are given in Table 1 Ex ~ _ 6 '~his is an example of a -three-layer material similar to Example 1 but having a different polymer, ~`
n~nely, polyurethane 3 clescribed above, in the topcoat and fleshcoat pastes. Also the substrate p~ste is made with coarser sodium chloride of average particle size 49 microns (negative deviation 18.5 microns; positive deviation 31 microns) and with 2.2 parts o~ salt per part of ~
polymer. Apart from this the method and formula- ~ -tions are as in Example 1. `~
~he propertiès of the material are gi~en in ~able 1.
Exarnple 6A
A single layer material made from a su~strate paste closeiy similar to the substrate paste of ~i Example 6 (diffexing only slightly in salt particle `
; ~ 20 size~using the same method but at considerabl~
increased thiclness has its pxopexties listed i~ -`
~able 3 and the result o~ mercu~y intrusion ~;~
penetrometry listed in ~able 4. -~his is an e~ample o~ a three-layer material : .
similar to Example 1 but having a di~erent pol~mer, namely~ po]yurethane 1 described above, :in the ;~
tQpcOat and fleshcoat pastes.
~he method and ~ormulations ~re the same as .. :
30 Example 1 eæcept that in the substrate paste lo90 `~

KD~K/SdeR

1' : ' `

105~

parts of sodi.um chloride are used per part of pol~urethane.
'~he properties of the material are given in~ :
~able 1. ~
5 ~ le ~ ::
'~his is an example of a three-layer material simi.la.r to Example 1 but using smaller particle size salt in the substrate and a harder pol~mer in t~e fleshcoat and topcoat layers, namely, the same polyurethane 1 as used for the substrate~
~he ~leshcoat, substrate and topcoat were laid doN~, coagula-ted, leached and dried in a ~ r similar ~anner tothat described in ~xample 1. ~
~he substrate ~o~mulation di~ers from ~ ~:
15 Example 1 in using sodium chloride of 17 microns . ~.
- a~erage particle size and 2.05 par-ts of sodium ~ -. chloride per part of pol~ret;haneO The fleshcoat ~, .
and topcoat formulations are the same as those ~ .
used in Example l apart ~rom the different .. 20 polyurethane.
~ ~he properties o~ the product are give~ in~ :
: ~ ~able 1.
: All these examples have elongations at break in the range 375% to 500/a.
25 _ DLD~ to ~0 ~ ;~
urther examples illustrating the e~eGt of varying substrate thickness~(EXamples 10 to 13 and ~ 1~ to 17) and salt ratio (~xamples 18 and 19,.20~ ;
: and 21 and 22 to 24) are gi~en below in '~able 1. ~ .
All these examples have elongations at break 26 _ KDN~/SdeR

~o~

in the ran~e 375~o to 5Q~/o. `
~i ' :
These are further examples illustrating (in Example 25~ the use of a polyethel polyurethane (polyurethane 4 above) in the outer layers and in the other examples the effect of changing the layer -thickness ana density relationships~
... . .
~he details of salt ratio, polymer layer ~` -thickness~ salt par-ticle slze and physical proper- ~ i ~0 ties are given in ~ables 2A and 2R below.
Comparison of Examples 26 and 27 demonstr~të
that only a very sli~ght improvement in out tear/
sti~fness is o~tained by disposing the standard topcoat as two thinner layèrs on either ~ace of the .
substrate. Comparison of Examples 28 and 27 ndlcate~ that the use of coarser salt in the sub strate v~ mark~dly improves the cut tear/ `
stiffness ratio and comparison of E~ample 28 with ~ ; .. , ; Example 29 demonstrates the further improvement 20 obtained on reducing ~he thickness of the substrate. `
~omparison of the pairs of Examples 27 and 30 and 29 and 31 respectivaly indicates the drastically ~ - .
lower cut tear/stiffness ratio which results when -~
`~
~ the substrate layer is not thicker and more dense - ~-; -~ 25 than the fleshcoat and topcoat layers.

l 27 ~ KDNK/Sde~

' - `~`,' '' ' ;-;
~ , ..... _ .. . .. . . . . , .

Examples 5 and 6 and 25 we:re compared for their resistance to hydrolysis~ 2 inch by 2 inch samples were separately s-tored-in the vapour contained in a closed cham~er held at 90C., the li~uid phases in the two chambers being distilled water and 0~085 g~l a~ueous ammonia. ~he samples were examined daily for the first appearance of surface cracks on hand flexing, the first value ~uated, and fox crumbling o~ the material on hand ~lexi~g, the second value ~uoted. ~he ma-terial o~
h~amples 51 6 and 25 showed sur~ace cracki~g after 17, 17 and 21 days in the ammonia vapour and 3~, 33 and 46 days in the water vapour and crumbled (to~al failure) after 18, 18 a~d 29 days in the :
15ammonia vapour and 36, 38 and 50 days in tho water vapour.
: :
~ ~ s demonstrates the improved hydrolysis ; ~ resistance of a material having polyether polyure~
thane in the ou-ter layers. ~; -:: : , ~ ' ` , :

. ~ ~
",~

~N~/sdeR
' :, , 1 ~ ~ , -, ' "

. -, . ... . ~ . . -i - .. . ;
o o o o ~o ~ o ~ : l Ir~ U~ ~ CO O O
O ~ O ~ rt O O ~ ~ t~ ~ t.~ ~ .
_ ,, , ., .~ ~1 ~ rl rl rl rl 0 r~ r~ CO 0 a t~

0 0 ~ ~ rJ ~ u~ '' ~ ' ~
- x u~ ~ u~ ~D ~ o ~ ,~
; o o o o o t~
~ ~ 0 0 ~ u~
o ~ .
~ ~ c~ . c~l c~l C\l C~ C~ C~l C~t C\l C~l C~l - _ _ _ _ _ _ .
.~ a.I~a~/sw~ 'I ~ ~I o~ ~ ~ ~ ~ CO t- o~
~ j I < Z ~ a',~ c~ co co ~ ~ ~ 0 co c~ T
!t ' SWIII 1!~ CO 1~ 0 1-~ 0 C~l N ~1 o~
-~sau~T~ c~
BO~ T~sal~l o o o o o o o o o o O o . .
. . ,- ..
o ~ ~ O C~l O U~ U~ C~
j ~ ssau~loFtl~ o CJ~ co co co co co c~ cr~ cO
' ~ `3:~e.1~5q~1S
.,; 11}1~ ~ ~ ;t ~ Cl) C~Ji~ ~ ~) 0 ;t O .
; ' ? - ¦ SSaU~IOTl~. . . ~ ia: - i ~o~ dc)ico o o o o o o o o o o o --~ . _ - .' t ~ . . u~ ~o ~ o;5 :~' `c ' , ssauYo~, ~ ~0 ~0 ~ u~ 0 ~0 ~0 ;~ U~ ~ . ,, '; ~"
e~;C r rl rl rl rl rt irl re rl ~ rl l ~ ~

? ~ ~ UTSa~ ~e, ~ ~ ~ ~ -~æ~ uæ~ ,æ U~ ~æ ~ ~
. , O . rt rJ rl ~--~i ri rl irl t r i ~i rl ~ ~
1 ~ ' ~ ~ ~ ~ ~ ~
, - - . ~ ~ ~IaW~lcjt~ t~e C~l ~ t~ t~ ~ rt r~ rt ~ 1 1 t~ ~ ` ;
~ re ~F ` ~ ~;
$ O~ e rt t i rt rl r.! rl ~ u; u; ri r. .! - ~ :
~Ge~ c~ c~cr o rl c~e ~ O - O cr cr~ C~ I
*1tS r~ i rl C~i C~i t~i r~ C~ J r~ `
aZ~S -~ F~ ~ ;
,~ a~;[ ~ rFi ~j t ~ ~i Cc ~ j r~ r - ' ' - . UTSa~ N N C~i æ æ ~ c~ æ N~ `NR ~æ ~Oo~ ;
a~Bl~sqns . ~ :

la~ od re re I tre r~ -I r-l . r~l rl rt rt r~
.~ a~B~ ns r -C~ ?X ~[ --I t~ C~ o~ rt ', ~ .j . 1~?5Z~lg6 : I . 29 - . . . . . .-. -.-. ' '~ 1 , " ' ' `
~, .
~:' :, ~L05f~9~
~ ___ .... _ . _ .. , a~l'lr 3~/S1122.~
Z ~ ~3-~ a,~ ~ ~ 2 cu t~
- ' 1'e~lT, __ -CSU3p t~ t~ C\l t~
20 ~ I I
SS3U~ . d~ r-l C~l C~
~o ~ ~s a~ t ~ r-l r-~ t~ ~D L~ -.. ,, O o O O O ~:
~ ~ ~ ~ t~
TSU~p ~ ~ t~ t~
a~sqns oooooo .,. :~
ss3u~1~F~I~ 0~ r-lr-l sqns . O O
O r-l r-l r-l O O O : : -suap r-l Ci~ t O O O O O O . :':
: ?~
SSaU~I~)Fq~ O ~ J ~ r~
~00 aO~r.
I ssa~ Ft~ u~ ~ ~ ~ u l~2~0~; r; r-i ~i r;r-i r; rt )`
.. F~? ..._ ; `~
H ~a~F~ce,[ r-l ~ ; ~

~, ~ UFS~)~'C\~ N C~
- 0F~r2~ r-l r-l r-~ r-lr-l ~I r-~
"2S t~'~ 1~ t~ ~ t~
o -~
a~ Oa ~ r~ r~ r~ r-l o~e.I rl r-l r~ r!r-l r~-l r~l .~ -~ eS t~ c~i N C~
,Qe FS C~J N C~J N C~
al~F~Xed L~ r-l r-~
. _ )UO ~) U ~T S a.I ~
a~e~c~sqn~ c~l o o o o o o .~
,Ia~ 0d . ...
a ~ e2~s qns r-l r-l r-l r-l r-l r-l r~l ald~ex~ u~ N C~ CO ~ O r~
- '. . :'': , :

~ ~''~ ', ;. ' --- 31 ~ : -KDN~/S~eR -' ,~, . .

1;
- ..

. ..
~l~ea.xq ~ o o o o o o ' UOF~UO'~ ~ I ~ -~
___ . .

IaI'',.S C) ~ ~ O o~
a~ a~
~:~
... . _ ~ L- I I I I I ~ ~ -P~
I - ,~
o o o o oo U~

~ ~ r- ,~
~1 .
N H 1:4 rl CO r- Lr~
.. .~ . . ~~.
::
D~ IS~ r~
'O O O O' O O ,'~

~ ~ ~ o o' ~: : ~i `~

C~l N C\l N N

:: : : ` :; :' ~.:
~`: :' -~.D~I~/SdeR
-- ~., . ;, .
:

:

~o~
~otes on Table-~ 1, 2A and 2B
Cut tear o.r tear propagatio~ st.reng~h is me;asured as descri.bed belol~ u~der (~I) in connecti.on with ~ab:le 3r Stiff~ess is measu.red by the following m~thod.
'.rhe method seek~ to represe~t the forces.
xe~uirea by the tendo~s of the foo-t to deform a fold in a shoe vamp. Referri~g to ~igure 9, a sample of material 50 which is 7 cm. long by 4.5 '~ -~
cm. wide is c:Lamped in a jig 51 with its outer or topcoat sur:~ace, e.g., 13 bowed outwardly and a length 529 53 of 20 cm~ from each e~d e~closed within the clamp~ the ends within the clamp being 20 cm. apart so as to form an in~erted U~shaped ;~
trough~

~he jig is located in an Ins-tron tensile testing machine and 15 cm. diameter metal rod 55 . '~
~ixed into -the cross head and lowered at a rate of '~
2.5 cm/min~te o~to ~he top 5~ of the inverted U-shaped sample, -the rod bein~ parallel to the plane bottom ends of the sample and perpe~dicular to the . ~ ~
longitudinal axis of the in~erted U~shaped txough .'~;`';,' .
(See Fi~ure 9). ~he stiffness is defined'as -the .
laod re~uired to make an inde7lta-tion ~.5 mm~. deep . '-. ...
in the bottom of the inverted ~-shaped'sample. 25%
iti.al modulus and wa-ter vapour permeabil:it~ are -~.- '.
measured as descr;ibed below for '~able 3. .
WVP A is the value for the mal;erial before ;~
surface finishing, WVP B is the ~alue for the material after _ 33'~
' KD~/SdeR '~ :

~ 5~1916 surf~ce fini~hin~ he same surlace finishin~r trea-tment is given to each sa~ple. It imparts improved resistance -to p~netration by li~uid ~ -water and to soilin~ and converts the sur~ace from a dull matt finish to a lustrous deeper coloured finish~ and imparts a grain appearance to the treated surface, and confers upo~ th~
_ product a leatherlike break.
~he spraying is carried oùt as follows:- ~
1~.9 parts of a 31% solution of polyester ~ ;
polyurethane made as above (polyurethane 1~ is thoroughly mixed with 7.1 parts of DMF and 0.4 parts o~ ~ perba black. 7.52 parts of the i~
resulting blend is mixed with 43.24 parts of ;~
additional ~M~ ~4.53 parts of c~clohexanone and 14.71 parts o~ acetone~ ~hi.s ~i~ture is spr~yed;~
onto the sheet material while hot air is supplied fxom a fish-tcail, being directed against the sur~ace of ~e sprayed sheet. ~he temperature of the air`~ ;~
measured two inches inside the ~ishtail is about ~- 110C. but after it leaves the fishtail it mixes ~;~ with the cooler ambie~t air so that the temperature o~ the hot air blast just abo~e (e~g~, 1 inch above~
the surface of -the sheet is probably about 80C.
2~ In the spraying operation the solution is atomised with air under pressure (80 psig~ in a standard spray ~ m situated 12 inches above the microporous sheet~
Just as it is leaving the sprc~y zone the ....
~ 30 sprayed sheet encoun-texs a blast of ho-t air directed .
~D~ de~
.:'-' '' :' ~ . .. .
' . ' ~Q5~9~, at its upper surface at a small angle (e.g., an angle of some 15 so that the blast is almost parallel to the upper surface of the sheet~ '~he aix is supp]ied from a flatte~ed tube (a 'Eishtail') whose outlet is about 2 i~ches above the sheet a~d about 1~ inches from the centre ot' the spray gUll~ measured horizontally along the path of the moving sheet, which is moving at 5 feet per minu-te. ~he hot air blas-t serves to 10 fuse the DMF-containing pol~ure-thane at the surface of the sheet.
~he sheet -then passes through a hot air oven (having an alr temperature~ in a fixst æone of g3a. and in a second æone o:E 12la~ ) to drive of~
Yy ~ 15 residual ~MF: thè rssidence time in the oven is ~;
~- three minutes. ~he product has a black lustrous bu-t fi~e~grained appearance li~e -that of smooth fine black ~al~ Its thic~ness is about the same ~ as that of the original sheet. ~he increase in `~
- 20 dr~ weight is about 1 to 2 g~ams~s~. metre. `~
~ ~ All the eæamples have values after finishing ; of 50 or more and these values are all ~uite satis~
factory for shoe upper purposes since values as low `~
as 40 are ~uite suf~icient to produce comfortable 25 men's-shoes~
~ .:: .: .
Alt-ernative or additional fi~ishing processes such as coat:ing~ printi~g and embossing ca~ also ~ ~
be emplo~ed~ ~ -.. ..
: ': ' ' KD~ng/~deR -35~ ;

' Density measurements in Tables 2A and 2B were obtained by splitting the layers away from each other with a band knife splitter and measuring the thickness and weighing the sample.
Example 32 A material was made in accordance with Example 1 using as the topcoat and fleshcoat polymer polyurethane 3 and polyure*hane 1 as the substrate polymer.
The topcoat and fleshcoat formulations were as in Example 3. The substrate formulation contained 32.5% polymer by weight based on polymer and solvent, 2 : 1 parts by weight of sodium chloride based on polymer; the sodium chloride had an average particle si~e of 40 microns as measured by Coulter counter.
The unfinished material was split on a band knife split-ting machine and the properties of the separated topcoat, substrate and fleshcoat layers measured. -The topcoat and fleshcoat layers were microporous layers about 0.35 mm. thick whilst the substrate was about 0.75 mm. I
thick. I
The tensile strength of the substrate was over three ~imes that of the stronger of the two other layers, namely, about

6 kg./cm., and its initial modulus over ten times that of the ;~
stronger of the two other layers, namely, about 1.5 kg./cm.? but its elongation at break was of the same order as the values for - -~
the other two layers, namely, in the range 300 to 450%.

~;'' ''` ' ,' ' '' ~ "
- 36 - ~

~i(35l~g6 L~ 3 . ' ' - ._ EXA~LE lA 6A
-- .
Average salt part.icle - 2715(4) 50 siæe (B) - - - :~ ~
Posi-ti~e deviation ~10( ~17 . ,~ .
.;. Negative de~iation -lO( ) -17 . . S~l-t/resin ra~io (A) l.90:l 2.20 Dens~y (~) 0~45 . 4 .~ ~hickness (mm) ' l~ 40 1~ ~3 Weigh-t (g/sq.m) 652~5(2) 652,5(2? ;;
ear Prop~ga-tion (Hj l.83(l) : 2.~7(~
(Cut Tear) l,92(2) 2.50(2) ` ~ot ch tear (~) 4.l7~2) . ~. 45(2) ~;
:. . . - ~ear.Propaga-tion/ (z) 2 .
.' notch tear 46~o ` 56qot ) . - ~ -ensile s~reng~h (D) -ll,9(2) l~.5(2) Initial modulus (~) 2.3(2) . 2.3~2) - ;~

: W.Y.P. ~ (G) . l~0 .~ l25 ~-i . . Porosity (M) 6~ 5~05 . Mean po~e (N~ 7,2 . lO
diameter.

., - - . ,. - .
- . .

., , . ... . . . - ... . . ~.
- ~ 37 .. - R~ K~saeR .
., . ... . . , . - . :

.. ': . - . ~.. :
........... ,. .. , . .. :.. : .,.. , ,. . . .. . , .. ,, ,. ; ., ~ 6 Notes on Tc~
(l) results uncorrected (2) resull,s adjllsted to 1045 ~n~ thickness and 00l~5 gr/cc density.
(A) 'rhis is the ratio in parts by weight.
(B) '~hese valucs are measured by ~edimentometry.
This gives values in very close agreement to those obtained by use o~ a Coulter counterO
~ 4) '~his is the average particle size.
(5) Th;s is the positive deviation.
~6) '~his is the negati~e deviation.
(C) grams pex cc. obt-ained b~ weighing a measured a:rea of` the sheet product of measured `~
thicknessO , ., (D) kg. per cm.
(E) At 25yo extention in kg. per cm~
~F) kg~
(G) Water vapour permeabilit~ in grams per s~. metre ~ -~
per hour at lOOyo relati~e humidity and 37C. ` -~
~D), (~ ), (G) and (~3 are measured b~ the ~ethods set out in Belgian Patent 732~82.
(H) Cut tear or tear propagation is measured in `
kg. and the measurement is carried out on a i ~ ~ tensile test machine o~ the constant rate of ~ -`~ 25 - tra~erse type, e.g~, as described :;n Belgian ;
~; . ", . .
Pate~t 732~82, eOg~ ~ an Instron tensile testing ~ machine. 'rhe sample used i5 cut with a single ; ~ stroke of a press with a kni~e edged rectan~ular punch having parallel long sides 75 mm~ long and parallel short sides ~5 mm. longD

2~ _ KI~ deR ~ ~

~5~ ~ 6 cu-t 20 mIQ. long is rnade in the specimen wi~h a sharp knife running from the middle ~:
Or one short ed~e parEIll.cl to the long edges~
The jaws of the tensi.le machine are set 20 rnm. apart and one edge 22.5 mm. long is gripped in one jaw and the other edge 22.5 mm. lo~g is grippcd in the other jaw. The specimen;is sub~ected to an increasing load by separating the j~ws at 10 cmO per mi.nute un~il the specimen is torn along the cut.
~he cut tear stre~gth of the product is defined as the average e~uilibriurn value of the maximum load which is recorded~
(M) ~ irst -the apparent volurne of the sample is determined b~ geometry~ ~he true ~- ~
volurne o~ solid i~ the sample is determined by ~ ~`
evacuation of the sample followed by intro~
duction o~ helium to atmospheric pressure and `~
the volume so int.roduced is measured~ ~he dif~erence between the apparent and true volume gives ~he t~al voi.d volume or porosi~y . ~ ~
` (N) ~ - ~he term ~ . .
pore size or pore diameter used herein is the `;~
value ob-tairled b~ the following experimental ; method. Pore size in this sense is not t-he maximum dimension o~ the voids in the material but re~lects the dimensions of the holes or pores in the walls surrounding or de~inirlg the voids9 which holes provide intercommurlication EDNK/SdeR

:1~5~196 betwecn the voids.
~he pressure re~uired to fo~ce mercury through ..
a pore is inve.rsely proportional ~o the pore diameterO '~he volume of mercury forced ~hrough the pore i~to the vold is e~ual to -the volume ,~
o~ the pore and the void. ~he porosit~ o~ a:' sample is plotted a~ainst the pore size by' ~ ~ ",',' observation of the volume of mercury which can ., 'be forced into the sample from all sides at set ;~
pressures. ~he to-tal vold volume (see ~
above~ is composed of pores and larger voids e~tered b~ such pores cover.ing the full range o~
pore diame-ters each of which re~uires ~ercu.ry at ,~
de~'ini-te pressu.res to :~ill it. By pre~setting ,~
the mercury pressures (P) the volume (V) of. ~`
. mercury forced in is determined ànd hence the .'.
.~ . ratio at that pressure of , '~ ~-Vp . ` ~

20is determined. ~his is the porosity at that ~:~ ' , pore size~ ~ altering the mercury pressure the porosity can be plotted as a function of .
~ pore diameter. ~his will level off at some ;` value which is the to-tal porosity of the samplet ~ :
~.
iOeO~ all pores ana voids are filled with mercury. .,' ' 0.0~ micxons is considered as the lowest diameter. `'~:
~ - ~
he value so obtained is in very close agraement .
~` , to other'methods but has the advantage of show.ing the rarlge o~ pore diameters. ~he poi.nt ~ of inflectio-n i~ the curve is taken as the mean .. ., .~

KDN~SdeR
'c.
1 ~
',: -~ ~S'~ 6pore d~ameter.
q'he initial pressure used was 5 psi absoluteO
Water vapour permeability is measurcd as ~ollows: ~ ' 5~ h 3~ mm. high 70 mm. diameter jar wlth the top '' , , closed with a screw-on cap having a 60~5 mm.
diameter hole in it occupied by a 67.5 mm~ diametex sample of the microporous material is used in an , , air~conditioned cabinet maintained at 37 flC. and `~
, !, ~ .
at zero relative hu~idity by mea~s of ~ilica gel. ~, '' 25 mm. of distilled water are placed within ` '',~
the jar and the change in weigJ,~t 'w' i~ a speci~ied ;,;~
~- i time 't' measured 4 hours a~ter placing the àar in the cabinet and again at least 5 hours later is . :
recoxded. The water ~apour pe~neability 'wvp' ,'~
. . .
- 336.6 w grams per s~uare metre per,hour at 100% ~-~, ~ t ,~-H and ~7C. , ,-~.

; , .

., ., :

- . .. ~ , ,:
^, . :- . ~ , :

: ~ , ,: -: - ~

K~ de~
:

., .

~.: `' ~ ~ ;-~s~

~BL E` 4 . .

.
E{a~nple lA 61 D ~ ~ D
100 ~ 6.~ 6.~ 1 1.7 1.7 _ . _ - .
~ 7 . 9 1. '; 1. 6 2 .'1 1 5 0 5 rl 9 0 ~ ~ 6 2 . ~
~ _ . ..
~5 ~7 0.8 2 3.4 0.7 6 9.5 0.~ 3 'j.0 1.6 ~ - ~
, . .
l'j,~ 6 9 5 0 3.3 5.6 0.6 ~0 6 12.7 3.2 30 50.4 ~4,8 G.~ 40.5 64.3 51.6 ~1.5 G9~8 19.
. _ ~' 97 7, ~3 13 . ~ 4 5 7 5 . 7 5 . 9 ~ , . ~- .
3 . 2 55 B7 . 3 9 . 5 ~7 . 5 79 . 8 ~
. , ~- .,. -' 2.0 ~j7 90.5 3.2 '~9 ~2.4 2.6 ;~
. .;;. , ~.
1. 6 j7 90 ~ 5 0 508~r ~ 7 ~ ;
___ . _. ~
- ~ 1.0 ~i~ 92 1.5 '~1 8~.7 1.6~, ., . ~_ 0~3 59 9~7 1.7 51 ~5.7 0 . ~, . . . , _ 0.75 59 93.7 0 52 ~37.~ 1.7 ~
~, : , , , .............. I ~ `
O.S 50 95 1.3 ~ 4~9 2.5 0.4 60 95 0 5~ 92.~ ~.5 ; ~ ~ -. .. .~
0. 2 62 - 9~ ~3 97 .~ '5 .1 -. . ~
0.1 62 9~ _ 59 99,2-1.7 0. 0~5 62 . ~ g8o 9 0 . 5 59 99 . 2 0 - ~ -. . , . ~_~
0.05 63 1001.1 ~9 99.2 0 0 . 03~ 6 3 1000 ~ ~ 9 , I ~, ~ . O ~r~

- ~DNKfSdeR

: , ~2~
~ble 4 ~ ;
Column A i~ the Yo porosity of the sample due to pores greater than the value in microns given in the lefthand colu~n. ~his includes both the pores and the voids with l~hich the poxes coolmullicate. ' :'' Column B is the /0 of -the total porosity which the value on the same line in Column A represe~ts, eag., for Example lA, 4yO o~ the poxosity is due to por~s greater th~m 100 microns and this represents G.4Yo of the total porosity of 63% of Example 1.
~oll~nn C is -the dif:~erence between the value -. . .
on the line and the one in the line above for Column ~ B and thus represe~ th~ % o~ total porosity which is due to pores belween the value i~ that line a~d , the one above, eOgO~ ~or EæamplelA, 1.5% of the total porosity is due to pores which are grea~er ~ -than 75 microns but not grea-ter than 100 microns. ;~
Considering ~able 3 in detail in Example lA, ..
~ 20 52% of the porosity is due to pores between 604 - `~
,~.
~ and 10 microns, 13.5% between 5.0 and 6~4, i.e~
, : : 65.5/a between 5 and 10 microns and 9.5% between ; 3.2 and 5.0 microns, i.e., 75% between 3.2 and 10 microns; 6~.3% is between 500 and 17.5 microns; ;
?5 the average pore diameter is 7.2 microns.
or Example GA, 40% is between 12 a~d 1705 - microns~ 5~o is between 10 and 12 microns, iOe.~ 45%
between 10 and 17.5 microns ana 19% is between 6.4 . i ~ - . ~ .
~ and 10 microns, iOeO, ~o betwee~ 604 and 17.5 , , 30 microns; 7001% is between 500 and 1?-5 microns;

. ~ 43 ~ :
- ED.l~JSdeR
, .' ' , ~0~

the average pore diameter is 10 microns.
The examples described above are made on a porous polyethylene support.
One particular material suitable for use as the ~;
porous support which is both self supporting and has a ~ -degree of flexibility and gives a very good flesh surface appearance, is a porous liquid permeable sintered polymeric ~ -plastics material especially one made from high density polyethylene and preferably having an average pore size of 50 microns and more broadly 25 to 100 microns as measured by the method described in B~S~So 1752: 1963 using n-propyl alcohol.
The porous polyethylene ~or other suitable porous support which may be a tensioned woven belt and can be made ~ ;
of polymer or metal or combinations thereof) is very suitably one sold by Porvair Limited under the Trade Mark Vyon (filter grade). ~ ~
This material is formed b~ spreading an even layer of `~ -Ziegler high density polyethylene powder on a smooth metal surface and then placing the smooth metal surface and the layer in a suitably heated oven to cause the particles to sinter. The s`urface of the resultant sintered sheet which was in contact with the smooth metal surface is smoother than the other face and it is on this smoother ace that the ~ ;
layer iS formed.
The porous support used in the Examples was a material -of this sort having a permeability of 30 to 60 cu~ic feet -~
of air/minute at a pressure of 2n static water guage.
- ; . .
The material in accordance with the present invention ' ' ~ ' ' ~S'Z~96 ~ ~
. -' is preferably composed of elastomeric polyurethane and the invention is illustrated by use of a :Linear polyester based polyurethane of high elongation at br~c~k e.g. hundreds of per cent such as at least 300%, 500% or 700%.
The substrate itself also has a high elongation at break e.g. at least 200% and usually 300% to 500% or more.
However, many other polymers can be coagulated to porous form from solvent, and solvent/non solvent systems `
and it is believed that such other polymers could be formed into the novel product described herein. Further discussion ;~ of the polymer is given below. ;
The particular strength and wear characteristics required for the end use of the man made leather like material will determine the particular polymer formulation to be used for the substrate layer.
For shoe uppers high abrasion resistance and tear `
strength combined -~ith a reasonable extensibility and initial modulus to provide proper wear comfort on the foot are required.
Many thermoplastic polymers can be used~ for such purposes for example polyvinylchloride and its copolymers, acrylonitrile polymers and copolymers and polyurethanes or blends of one or more oP these. However we prefer elasto~
meric polyurethanes.
The elastomeric polyurethane may be used on its o~
or as blends with minor proportions say up to 49%
preferably less than 20% of poly~inyl chloride and other polymers and copolymers such as nitrile rubbers including solid copolymers of butadiene and acrylonitrile. 1 ; ~45~

.... .. ..

~ O ~ 3 Other polymers which have been suggested for use in man made leather like materials include polyacetal resins~
vinyl halide polymers (including copolymers with other ethylenically unsaturated monomers), polyamides, polyesteramides, polyesters~ polyvinyl butyral, polyalphamethylstyrene, polyvinylidene chloride~ polymers of alkyl esters of acrylic and methacrylic acids, chlorosulphonated polyethylene, copolymers of bu~adienee and acrylonitrile, cellulose esters and ethers, polystyrene and other polymers made from monomers containing vinyl groups, and blends of them with elastomeric polyurethanes 1~ can be used.
The preferred polymer however are!elastomeric polyurethanes having recovery properties intermediate between pure rubbers and pure thermoplastic materials at room temperature.
The article by Schollenberger Scott and Moore in ~ubber Chemistry and Technology~ Yol. XX~V, No. 3, 1962 ~ ~
pages 742 to 752 at page 743 and in Figure 3 indicates the - ~ ;
long so-called half lives of the polyester urethanes made from adipic acid, 1,4 butane diol and diphenyl methane ~
`i` p,p~ - diisocyanate by the methods disclosed in U.S. Patent Specification NoO 2871218 and sold under the Trade Mark ESTANE 5740. These two disclosures are incorporated herein , " .
by reference.
Polyurethanes may be based on a wide variety of ~ ;;
precursors which may be reacted with a wide variety of polyols and polyamines and polyisocyanates. As is well known the particular properties of the resulting polyurethanes _46-' 1~5~

to a large exten$ can be tailored by suitable choice of the reactants, reaction sequence and reaction conditions.
The preferred polymers are elastomeric polyurethanes based on a linear~ hydroxyl terminated polyester ¦although a polyether or a polyether/polyester blend may be used) and a diisocyanate~ with a small addition of a difunctional low molecular weight reactant. The last mentioned component may be added either with the other reactants at the start of a one-step polymerisation or at a later stage when it will act primarily as a chain extender.
This type of polyurethane having thermoplastic properties is particularly preferred for use in producing ~ `
sh~e uppers. Particularly preferred polyurethanes are those derived from polyesters by reaction with diols and diisocyanates. As is known from United States Patent ~ ~ -Specification No. 2871218 men~ioned above many diffent polyesters~ diols and diisocyanates can be used, but a particularly suitable polyurethane system is one in which a polyester made f~^om ethylene glycol and adipic acid is reacted with 1,4 - butylene glycol and with 4,4~-diphenyl methane diisocyanate. ~;
In the system in accordance with the above specification the mole ratio of polyester and diol can vary between quite wide limits but the combined mole ratio of polyester and diol is arranged to be essentially equivalent to the mole ratio of diisocyanate so that the resultant polymer is essentially free of unreacted hydroxyl or isocyanate groups.
Polymers of this type but having an improved Shore hardness can be made by using a sli~ht excess of diiosocyanate and also by using a copolyester as by replacing part of the ethylene glycol in the above system by 1, -butylene glycol A further alternative polyurethane system which has been found particularly suitable~ uses polyester derived from caprolactones. Such polyurethanes are described in British Patent Specification No. 8596400 The polymers may be produced by a bulk polymerisation process and subse~uently dissolved in suitable solvents or may be prepared directly in solution by a solution `
polymerisation process.
The polymer can include conventional stabilizers, ;`
filler~,~ processing aids~ pigments, dyes additives and surface active agents for example proofing or wetting agents, ,.
and when the polymer content is ~uoted in the claims this -~
includes any such additives which may replace up to 15% w/w of the polymer. ;~
A particularly preferred polyurethane is that made by the novel solution polymeri ation process disclosed in United States Patent Specification Serial No. 3709864 ~`;
Belgian Patent No. 7424710 Such polyurethanes are charac~
terised by having intrinsic viscosities in the range 0.9 to 1.40 The intrinsic viscosity is determined in highly dilute solution in analy~ical grade DMF which has been thorougly ;
dried by storage under a nitrogen atmosphere over a molecular sleve (Linde 5A). Four measurements at 25 C corresponding to ~ ;
four~ approximately equally spaced~ concentrations are madè

~ .~, . . ~ - , . .. . .. . . .. . .. .. ..

and intrinsic viscosity and polymer solvent interaction parameter are determined by the Huggins equation:

[~ ~ +
where ~ ~ is the specific viscosity and C is concentration expressed in g/100 ml, and ~ is the intrinsic viscosity~
For usb in making shoe upper materials the preferred polyurethanes have melting points of at least 100C
preferably above 150C (eOg. about 170 to 200 C~ as measured by differential thermal analysis or differential scanning calorimetry). When formed into a smooth void-free thin film 0.2-0~4 mm in thiclcness (by carefully casting a degassed solution in dimethylformamide and then carefully ~
evaporating off the solvent in a dry atmosphere) they -.~:
; ~ have the properties described below; a tensile strength of at least 210 kilograms per s~uare centimeter (preferably at least 350 e.gO about 420 to 600) ~ -a per cent elongation at break of at least 300% (pre~
ferably at least 400% e.g. about 500 or 700%3 a 100%
secant modulus ~stress divided by strain at 100% elong- ;~
~, ,, -.
ation of at least 28 kilograms per square centimeter (preferably at least 84, e.g. about 110 to 134~o These mechanical properties are measured by ASTM D882-67.
The preferred polyurethane (again tested as a thin film made as described above) recovers completely from a 5% elongation at room temperature (23C) but prefer4 ably does take on a permanent set (one measured for example j; -as in an ASTM D412-66) after 100% elongation. This set is usually within the range of about 5 to 20%~ as in the range , -49- I; ~ `

105~;:196 of about 10 to 20%, e.g. about 15~. The ~'permanent set~
is usually measured an hour after the release of stress;
for example, a material which shows a tension set of some ~ `~
24-26% immediately on release of the clamps after being held at the 100% elongation for 10 minutes will ~ave a;iten~
sion set of 14% measured 1 hour after the release of the clamps. (In the measurement a film specimen 1 cm wide with ``~
a gauge length of 5 cm is strained to the 100% elongation at a rate of 254% per minute). Preferably the material for the substrate layer haa a Shore hardness of at least 75A
(more p~eferably about 90A to 60D), measured by ASTM D vo6-67.
The use of polar organic solvents has been mentioned.
Many polar organic solvents could be used but DMF iS
preferred. ~ ~-The particular solvent which is used can va~y depending on the particular polymer composition non solrent and removable filler which are being used. The solvent` "~
should not react with the other components oP the system although it can form complexes with the non solvent e.g.
hydrates when the non solvent is water as lS believed to be ;~
the case with DMFo Also the solvent must be miscible with the non solvent, preferably completely so, and must be able : ,: , ~; ~ .,- :
to be extracted from the coagulated polymer. ~-Solvents which could be used instead of DMF
include amides~ esters~ ketones~ sulphones~ and phenols~
however preferred alternatlve solvents to DMF are dimethyl sulphoxide, N-methyl pyrrolidone, and dimethyl acetamide and blends thereof with cheaper solvents such as toluene and xylene which although not solvents for the poly~

_ urethane on their own do not act as non solvents when mixed with dimethylformamide.
The non solvent to be used will also vary depending on the particular polymer composition, solvent and removable :~
filler!which`~-are being used. Again the non solvent should be chemically inert ~o the polymer and removable filler though it may be a solvent for the removable filler and ~ ;
may form complexes with the solventO The non solvent should be miscible with the solvent and should be a non solvent for the polymer i.e. when added in excess to a solution of the polymer it shoul~ coagulate the polymerO
Suitable inert non solvent liquid include methanol~
ethanol~ water~ hydrocarbons such as benzene~ toluene~ chlorinated ~ ~;
hydrocarbons, such as tetrachloroethylene and chloroform, polyol9 such as ethylene glycol~ glycerol~ and l~ trimethylolpropane and glycol monoalkyl ethers and mixtures thereof which are ;~
mixible with the solventO However the preferred non solvent is water since it presents no recovery problems and is far cheaper than any of thealternatives;and moreover since it is a very good solvent for tbe preferred removable fillers~ namely ;
inorganic salts such as sodium chloride, it can also be used ~`
as the non solvent for the actual coagulation step of the processO ;
The removable filler lS preferab-~y a water soluble solid or a solid which can be dissolved by a non solvent ;~
compatible with the polymer. The removable filler could be one~ e.g. a carbonate or bicarbonate~ which can be removed by chemical action of the coagulating non solvent e.g. a `~ ~ -. ~. :
dilute aqueous acid or by thermal decomposition e.g. ammonium carbonate or bicarbonate but it should be chemically inert ~ ~ ;

during the actual coagulation stage to ensure that no gas bubbles are produced in the coagulated microporous structure.
IYhilst such alternatives are possible they add complications `~
to the process and are not preferred. -The preferred removable fillers are water soluble ~ -inorganic salts e.g. the alkali metal and alkaline earth ~;
metal and ammonium salts e.g. chlorides and sulphates or nitrates~ especially sodium and potassium chlorides and sulphates and ammonium sulphate, sodium chloride being ,::
10 preferred on grounds of cheapness, relative solubilities~

and ease of availability ;. ~' ,',~

i` ~ "`'~ ', . ~: ' .: : . ,, ..
i, ,- ~ . -. ,, ,: .. ~ , ~ -:. ::.: :

. ~ ~

; :^ , ~: :

It has been mentioned above that the topcoat and ~leshcoat layers are integrally adhered to the substrate, As car be seen from an inspection o~ the photo-5 micrographs, this adherence is no-t produced by a more dense layer at the lnterface between the layers but rather the walls between the voids continue unmodified apart from a change in wall thickness from one layer to the other. This desirable highly permeable structure - ~ ' 10. results from the preferred simultaneous coagulation'~
technique whereby all three l~yers are deposited prior to any coag~lation and then the unitary structure is ;~
e~posed to the coagulant.
The topcoat, as mentioned above, is preferably 150 given a ~inishing treatment. The preferred form of this treatment in~olves the formation of a thin densified but still permeable zone at the outer sur~ace of the ~ topcoat layer. This densified layer is normally for - grain leather-like products no-t more than 30 microns -thick .~
; ~ 20. and is~usuall~ less than 20 micronB thick, eOg. 1 to 15 ;`~
or 3 to 10 microns thick.
The surface of -the material when finished by~ `
the technique described above has -the following general characteristics when examined mi~roscopically. It has 250 a thin fused sur~ace la~er typically 1 to 15 microns -' thick with fewer pores penetrating its surface than the untreated material, i.e., less than abou~ 300 pores ¦ visible at 2GOx magniflcation i~ an area 360 microns by 360 microns.
3- The'material typically has less than 200 pores~

, ~ .

, : -, ~' KD~/FC0' -53- l ~

~'~7 ~s~p~
e.g. not more than 100, e.g., 10 to 100, and mostly .`~
30 to 703 e.g., about 50 visible at 200x magnification ~ , -in an area 430 microns by 430 micronsi~ mese pores ; are located in shallow craters typically 5 to 20, ~`
: -. .
` 5. e.g. 10 microns deep and 20 to 90, e.g. 50 microns wide. The pores in the bottom of a crater typically `~
_ have a bridged appearance provlding access to a number of pores in the interior of the material. The pores which remain are typically 5 to 30, e.g., ahout 10. ~0 microns in diameter and are thus generally larger than the pores in the unsprayed material~
- Each crater may contain a number of such pores ` typically 3, 5, 6, 8 or 10.
All the materials made by these techniques 75. have a ~ood grain break or crease pat~ern exhibiting a fine pattern of creases at the line of the fold ~ . . - .
when the material is folded sharply with the topcoat ii~ on the inside of the ~old.

t r.'~
~ ', .. .
KDNK/FC0 -54~
' ,; , ' '~.
, 1~, . ~ ,, '" ' ~

Claims (16)

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A water vapour permeable soft flexible sheet material suitable for use as the upper of a shoe in place of leather, said sheet material being at least 0.8 mm thick and up to 2.0 mm thick, being free from fibrous rein-forcement, and having an elongation at break in excess of 200%, comprising a strength imparting porous elastomeric polymer substrate layer disposed between a porous elastomeric polymer fleshcoat layer and a porous elastomeric polymer topcoat layer, the substrate layer having a higher density than the flesh-coat or topcoat layers and being thicker than either the fleshcoat or the topcoat layers the thickness of each of said fleshcoat and topcoat layers being 10 to 95% of the thickness of said substrate layer and the combined thickness of the fleshcoat and topcoat layers being in the range 30% to 175%
of the thickness of the substrate layer.

2. A material as claimed in claim 1, in which the strength impart-ing porous elastomeric polymer substrate layer has compact voids randomly dis-tributed through the layer intercommunicating via pores penetrating the walls between the voids, and the fleshcoat layer is microporous having compact voids randomly distributed through the layer intercommunicating via pores penetrat-ing the walls between the voids, the topcoat layer is microporous having com-pact voids randomly distributed through the layer intercommunicating via pores penetrating the walls between the voids, and the substrate is characterised by having wall thicknesses between the voids generally greater than those in the fleshcoat or the topcoat.

3. A material as claimed in claim 1 further characterised by having a cut tear strength as defined herein of at least 1.5 kg. and a ratio of cut tear strength to stiffness as defined herein of at least 4.2.

4. A material as claimed in claim 1, in which the substrate layer consists of a porous matrix of elastomeric polymer affording a plurality of compact voids intercommunicating by pores, the said substrate layer being from 0.5 to 1.5 mm thick and having a total void volume or porosity in excess of 50% and at least 65% of the porosity being provided by pores and the voids with which the said pores interconnect, the said pores having diameters of at least 5.0 microns and not more than 20 microns as determined by mercury intrusion pentrometry.

5. A material as claimed in claim 1, in which the fleshcoat and top-coat are integrally adhered to the substrate layer.

6. A material as claimed in claim 1 in which the substrate polymer is a polyester based polyurethane material having a Shore hardness of 75A
to 60D as a solid continuous sheet at 25°C, and in which the polyurethane polymers used for the fleshcoat and for the topcoat are polyester for poly-ether polyurethanes having a lower Shore hardness than the substrate poly-urethane.

7. A material as claimed in claim 1 in which the substrate layer has a porosity in the range 50 to 65% and less than 7% of the total porosity is provided by pores and the voids with which they interconnect the said pores having diameters in excess of 100 microns and at least 50% of the total porosity is provided by pores and the voids with which they interconnect the said pores having diameters in the range 6.4 to 17.5 microns.

8. A material as claimed in claim 1 in which the substrate layer when a cut cross-section is viewed is further characterised by compact voids the majority of which have maximum dimensions in the plane of the cross-section of 30 to 100 microns, the majority of these voids having shortest transverse dimensions in the plane of the cut surface of 1/4 their maximum dimension and above, the shapes of the voids being non-spherical and though irregular in outline compact in shape, the voids being separated by more dense regions which contain smaller pores visible at 150-fold magnification the majority of which are 1 to 30 microns across and spaced apart by 1 to 10 microns the majority of these denser regions being of 30 to 100 microns across between adjacent larger voids.

9. A material as claimed in claim 1 in which the fleshcoat and topcoat layers are microporous and when a cut cross-section is viewed are characterised by irregular shaped though compact voids from 5 to 75 microns across the majority being 20 to 50 microns across the said voids being de-fined or surrounded by thin walls 1 to 5 microns thick the voids intercommuni-cating by pores passing through these thin walls.

10. A material as claimed in claim 1 in which the substrate poly-mer as a thick void free film 0.2 to 0.4 mm thick has a modulus at 25% exten-sion of at least 55 kg/m2 and the fleshcoat and topcoat polymers as a thin void free film 0.2 to 0.4 mm thick have a modulus at 25% extension of less than 55 kg/cm2.

11. A process for making a water vapour permeable soft flexible material suitable for use as the upper of a shoe in place of leather which comprises depositing a layer of coagulable elastomeric polymer fleshcoat com-position on a porous support to form the fleshcoat layer, prior to coagulation depositing a layer of coagulable elastomeric polymer substrate composition on top of the layer of fleshcoat composition and a layer of coagulable elasto-meric topcoaticomposition on top of the layer of substrate composition, and'' then coagulating the composite material to an integrally adhered microporous three-layer structure free from fibrous reinforcement, at least the substrate composition and at least one of the fleshcoat or topcoat compositions contain-ing a removable particulate filler, the filler in the said fleshcoat or topcoat compositions having an average particle size smaller than that used in the substrate composition, said compositions being such and being deposited in such thickness as to produce a product which is 0.8 to 2.0 mm thick free from fibrous reinforcement, and having an elongation at break in excess of 200%, comprising a strength imparting porous elastomeric polymer substrate layer disposed between a porous elastomeric polymer fleshcoat layer and a porous elastomeric polymer topcoat layer, the substrate layer having a higher density than the fleshcoat or topcoat layers and being thicker than either the fleshcoat or the topcoat layers the thickness of each of said fleshcoat and topcoat layers being 10 to 95% of the thickness of said sub-strate layer and the combined thickness of the fleshcoat and topcoat layers being in the range 30 to 175% of the thickness of the substrate layer.

12. A process as claimed in claim 11 in which the substrate composi-tion comprises an elastomeric polyurethane dissolved in a polar organic sol-vent at 25 to 40% by weight concentration with a particulate dissolvable filler dispersed therethrough, which is substantially insoluble in the organic solvent, and the filler has an average particle size as determined by Coulter counter measurements in the range 20 to 200 microns and the ratio of filler to polymer is in the range 1.8 : 1 to 2.7 : 1 parts by weight and the flesh and topcoat compositions contain dispersed filler having an average particle size below 20 microns.

13. A shoe or other article of footwear having in place of the upper leather thereof a material as claimed in claim 1.

14. A process as claimed in claim in which the substrate composi-tion comprises an elastomeric polyurethane dissolved in a polar organic sol-vent at 25% to 40% by weight concentration with a particulate dissolvable filler dispersed therethrough, which is substantially insoluble in the organic solvent, and the filler has an average particle size as determined by Coulter counter measurements in the range 20 to 200 microns and the ratio of filler to polymer is in the range 1.8 : 1 to 2.7 : 1 parts by weight and the flesh and topcoat compositions contain dispersed filler having an average particle size below 20 microns.

15. A process as claimed in claim 14 in which the substrate composi-tion comprises a 30-35% by weight solution of polyurethane containing 1.9 : 1 to 2.2 : 1 parts by weight microscopic removable filler per part of polymer and the top coat and fleshcoat compositions comprise a 25% by weight solution of polyurethane containing 3 parts by weight of microscopic removable filler per part of polymer.

16. A process as claimed in claim 15 in which the average particle size of the removable filler in the substrate composition is in the range 25 to 50 microns.