GB2081279A - Lasting shoes with hot melt adhesives - Google Patents

Abstract

Hot melt adhesives for lasting shoes comprise a minor amount of a high molecular weight linear aliphatic hydrocarbon polymer and a major amount of a substantially linear copolyester having units in its molecular chain derived from aliphatic diol, terephthalic acid, and one or more aliphatic or aromatic dicarboxylic acids including a dicarboxylic acid having an aliphatic chain of not less than five carbon atoms. The specification describes lasting shoes with a hot melt adhesive comprising a polyethylene having a melt flow index preferably in the range 5 to 200 and a copolyester having units derived from butane diol, dimerized fatty oil acid, terephthalic acid, and isophthalic acid.

Description

SPECIFICATION Lasting shoes with hot melt adhesives This invention is concerned with improvements in or relating to lasting shoes with hot melt adhesives.

The word "shoe" where used herein is used generically to include outer footwear generally and Jncludes the article in the course of manufacture.

Various proposals have been made for adhesives for use in the lasting of shoe uppers. During the 'shoe lasting operation a shoe upper is drawn to the shape of a supporting last. Marginal portions of the upper are wiped or drawn across the shoe bottom and secured to an insole mounted on the last. Usually the lasting operation is performed using machines designed to operate on toe, side, or heel portions of the shoe, or combinations thereof. It is required to secure these marginal portions to the insole in such a way that when the wiping instrumentalities are removed, the marginal portions of the upper remain in their wiped positions.

Modern lasting machines intended for use in lasting toe end, side, or heel portions of the shoes are designed to operate quickly and require that adhesives used are applied readily and set sufficiently to hold the marginal portions of the upper adequately even though the wiping instrumentalities may dwell in their in-wiped position for only about two seconds, or not at all. Also, some manufacturing operations carried out subsequent to lasting are carried out at high temperatures, and it is therefore a requirement that the adhesives used for lasting should withstand temperatures in excess of 1000C so that the shoe can remain in its lasted condition.For example, side lasting cements may be required to have softening points of more than 1 200C, more often in the range 1500C to 2100C, and often in the region of about 1 70C to 2000 C. These and other requirements impose restrictions on the time in which the adhesive must achieve a bond and on the flexibility and heat resistance required. Also, the adhesion characteristics must be such that shoe making materials used are adequately bonded; more commonly used shoe making materials include leather and PVC upper materials and insole materials, for example latex bound fibre board, e.g. "Texon" (Registered Trade Mark). Other materials offered for shoe making and to which adhesion is desirable include PVC and "skinfit" lining materials.Skinfit lining materials comprise synthetic materials including a fabric inner layer e.g. of woven polyamide and a foam layer e.g. of polyurethane, and are comparatively difficult to last using machines in which the wiping instrumentalities do not dwell in their in-wiped position, especially when making ladies shoes.

Modern lasting machines adapted for use with hot melt adhesives are equipped with facilities for accepting and melting the hot melts in various forms for example hot melts supplied in flexible rod form or as granules. In the case of rod form hot melt adhesives, further requirements are imposed on the adhesive in order that it may be supplied as a flexible, coilable rod which can be unwound from a coil and fed into the lasting machine by a rod feed device of the machine.

Hot melt polyamide adhesives are commonly used for side lasting operations but are considerably more expensive than the type of polyester hot melts frequently used for toe lasting operations.

Butane diol terephthalate copolyesters are known to provide commercially acceptable hot melt toe lasting adhesive compositions. These materials tend to set quickly from mobile liquids to hard solids over a comparatively small temperature range, without demonstrating a tacky cohesive condition to any significant extent at or near their melting points. Also, it is necessary in order that the adhesive have good cohesive strength to employ comparatively high viscosity materials, which tends to result in more difficult extrusion of the cement onto the shoe during lasting.Consequently, although such materials can be formulated to be acceptable for toe and heel lasting, they tend to be less acceptable for lasting operations in which lasting instrumentalities do not dwell for any significant period of time to hold the marginal portions of the upper against the insole whilst the adhesive composition sets between them, and for lasting operations where the ability to bond a variety of materials, together with toughness of the adhesive bond and a stable rod form of the adhesive are desirable.

It is one object of the present invention to provide an improved method of lasting using a hot melt adhesive composition.

We have found that satisfactory lasting of side portions of shoes may be achieved by use of selected hot melt adhesive compositions comprising certain polyesters and certain high molecular weight linear aliphatic hydrocarbon polymers.

We have observed that these selected adhesive compositions can be extruded into rod form at suitable viscosities, and demonstrate satisfactory adhesion to a variety of materials including PVC lining materials which are not readily side lasted by known hot melt adhesives using a progressively operating side lasting machine. Adhesive compositions for use in a method according to the invention demonstrate low stringing of the adhesive at higher viscosities and a desirable degree of crystallinity, together with tack and cohesive properties over a temperature range at or near the melting point, i.e. a less sharp setting, hereinafter referred to as their jammy nature.

The present invention provides, in one of its various aspects, the use in a method of lasting a shoe in which marginal portions of a shoe upper are secured to the insole by an adhesive composition, the use of a hot melt adhesive comprising a minor amount of a high molecular weight linear aliphatic hydrocarbon polymer and a major amount of a substantially linear copolyester having a molecular chain made up of units corresponding to diol units and acid units derived from (a) one or more aliphatic diols; (b) terephthalic acid to an extent of not less than 60 mols per 100 mls of the acid units; and (c) one or more aliphatic or aromatic dicarboxylic acids including a dicarboxylic acid having a difunctional aliphatic hydrocarbon residue having not less than five carbon atoms in the molecular chain, the units being so selected that the adhesive composition has a softening point (Ball s Ring) in the range 120 to 2100C.

Adhesive compositions for use in a method according to the invention may have melting points (Ball a Ring) within a wide range of temperatures dependent on intended cpnditions of application and the materials to be lasted. Compositions with melting points in excess of 21 OOC are inappropriate for use in existing lasting machines.Whilst compositions with melting points as low as 1 200C may be acceptable in some instances, for use with side lasting machines adapted to operate automatically to simultaneously last both sides of a shoe progressively by means of lasting roll means during relative movement between the lasting roll means and the shoe lengthwise of the shoe (hereinafter referred to as "progressive machines") e.g. by use of a roller operating to wipe in and press down opposite side lasting margins to which adhesive composition has been applied in a single pass along the shoe, we prefer to employ adhesive compositions having softening points (Ball a Ring) in the range 1 700C to 2000C.Similarly, the adhesive compositions may have a viscosity within a wide range, and we prefer to use compositions which when manufactured have a viscosity in the range of about 500 to 1 500 poise at 2400C as determined from Brookfield Thermocell viscosity measurements; compositions with viscosities lower than 500 poise tend to have inadequate holding power to secure some stiffer shoe making materials when processed in progressive machines, whereas materials with viscosities greater than 1 500 poise tend to be rather difficult to extrude during lasting. When using a progressive machine, to carry out a method according to the invention, we prefer to use an adhesive cornposition with a viscosity, at the time of manufacture, in the range 900 to 1100 poise'at 2400C.

Aliphatic diols for use in preparation of the polyester preferably include saturated aliphatic diols HO(CH,),OH in which n is an even number, and especially 1.4 butane diol. The glycol components may also comprise a small proportion of a long chain glycol e.g. one having a molecular weight of between 1,000 and 10,000, provided the resulting copolyester has some affinity for the hydrocarbon polymer. If desired, the aliphatic diol may include one or more diols having methyl or ethyl substituents on the molecular chain. Other short chain aliphatic diols e.g. ethylene glycol, 1.6 hexane diol, and mixtures thereof may also be used, but in general we prefer to employ 1.4 butane diol to provide at least 50 mole % of the diol units in order to achieve desirable adhesion and crystallinity.

In order to achieve softening points and crystallinity of the composition as required, we employ copolyesters having not only substantial quantities of terephthalate units, but also significant quantities of units from another dicarboxylic acid. Incorporation of units derived from other acids andXor diols in the molecular chain affects various properties of the polyester, including not only the softening point but also for example adhesion, crystallinity, viscosity, and flexibility of the composition. Terephthalic acid residues (because of the molecular structure of terephthalic acid which can be regarded as having carboxyl groups arranged at opposite positions on a benzene ring) present in the polyester molecule tend to increase the crystallizability of the polyester. Incorporation of units from aromatic acids, e.g.

ortho and isophthalic acids, influence in particular melting point and crystallizability of the polyester. We prefer to incorporate units derived from isophthalic acid. It is important that aliphatic moieties of the copolyester molecule show affinity for the high molecular weight linear aliphatic hydrocarbon polymer used, because this influences, to a marked extent, the jammy nature of the composition and its viscosity. For example, aliphatic dicarboxylic acids having less than five carbon atoms in the molecular chain tend to lead to poor side lasting bonds.Suitable aliphatic units may be derived from aliphatic dicarboxylic acids having not less than 5 carbon atoms in their difunctional aliphatic hydrocarbon residue including so-called dimer acids and those acids having from 6 to 12 carbon atoms iri the hydrocarbon residue as exemplified by dodecanoic acid, azelaic acid, sebacic acid, and mixtures of these, Sebacic, azelaic and other aliphatic dibasic acid units when present in the molecule with the phthalic acid units introduce spacing between the benzene rings in the polymer chain and impart a flexibility to the polymer chain. This spacing appears to be significant in relation to the required compatibility with the aliphatic hydrocarbon polymer. We prefer to incorporate units derived from a dimerized fatty oil acid.A dimerized fatty oil acid may be obtained by the polymerization of a polyunsaturated vegetable oil acid, for example linoleic acid from soybean, cotton seed our linseed oils, by the process described in U.S. Patent Specification No. 2,482,761, in which the oil acid is heated in the presence of water using sufficient pressure to prevent decomposition. The dimerized fatty oil acid produced has an apparent molecular weight of about 600, an equivalent weight of about 300, and usually comprises about 95% of molecules comprising 36 carbon atoms and having two carboxyl groups, the balance comprising some monomeric acid and some trimer molecules comprising 54 carbon atoms and having three carboxyl groups. We prefer to use a dimerized fatty oil acid in which the proportion of monomer is less than 1%, and of trimer less than 6%. However, a dimerized fatty oil acid comprising up to 25% of trimer may be used. A hydrogenate of dimerized fatty oil acid may also be used.

We prefer to use a polyester having diol units derived from 1.4 butane diol and acid units derived from terephthalic acid, isophthalic acid and dimerized fatty oil acid. Preferably the polyester has from 2 to 20 mole % units of dimerized fatty oil acid and from 98 to 80 mole % units of a mixture of terephthalic and isophthalic acids, more preferably not more than about 5 mole % of the dimerized fatty oil acid units and not less than about 95 mole % of terephthalic and isophthalic acid units. We also prefer that the terephthalic and isophthalic acid units provide from 60 to 90 mole % of the acid units and 8 to 38 mole % of the acid units respectively, more preferably from 70 to 80 mole % terephthalic acid units and 1 5 to 25 mole % isophthalic acid units.

As will be understood by those skilled in the art, the acid units of the polyester may be derived not only directly from the acids themselves but also from their lower esters (e.g. methyl or ethyl esters), where it is necessary or convenient to do so.

Presence of the aliphatic residues in the copolyester in particular those from dimer acid enables sufficient amounts of the high molecular weight linear aliphatic hydrocarbon polymer to be included in the adhesive composition. These polymers tend to be incompatible with the polyesters more usually employed in quick setting toe lasting polyester hot melt adhesives, whereas with the selected copolyesters used in adhesive compositions for use in the present invention, up to 20% or more by weight of the polymer may be included without experiencing problems of poorer extrudability and lack of holding power when used with progressive lasting machines, which one might associate with incompatibility.Suitable high molecular weight linear aliphatic hydrocarbon poolymers include the polyolefins, especially the homopolymers of ethylene; low density polyethylenes are preferred especially those with a melt flow index of about 5 to about 200, which is to say a molecular weight of about 30,000 to about 90,000, and mixtures thereof. By melt flow index is meant the weight of material in grams extruded through a standard die orifice in 10 minutes at 1 900C and is defined in British Standard BS2782 Method 105C. Polymers with a melt flow index of 5 to 30 are more preferred.

Preferred polyethylenes are supplied by ICI Plastics Division in the U.K. under the Trade Mark Alkathene. Grades 17 (melt flow index 7), 19 (melt flow index 20), and 23 (melt flow index 200), have all been found satisfactory, the higher molecular weight grade, Alkathene 17, being preferred. These materials may conveniently be employed in the form of a coloured masterbatch during manufacture of the adhesive composition.

Presence of the high molecular weight linear aliphatic hydrocarbon polymer in an adhesive composition for use in a method according to the invention leads to adhesives which demonstrate a tacky, cohesive nature over a temperature range of several degrees at or near their softening point This tacky cohesive nature is particularly beneficial in side lasting operations in which the lasting margin is held tightly to the insole by lasting instrumentalities of the lasting machine for only a short period of time.By use of such adhesive compositions, materials may be held in their lasted position, even though lasting margins immediately after progressive application of the hot melt adhesive composition thereto are merely drawn into position and pressed momentarily into place against the insole by lasting roll means during relative movement lengthwise of the shoe between the shoe and lasting roll means. In addition to influencing physical properties, i.e. the "jammy nature" of the adhesive composition at or near its melting point, the high molecular weight linear aliphatic hydrocarbon polymer influences also the adhesion characteristics of the adhesive composition and appears to enhance the ability to bond, in the lasting process, various shoe making materials, including for example PVC linings.Also, these adhesive compositions can be extruded into rod form without undue difficulty to yield consistently rods of uniform cross-section. Whilst substantial quantities of the polymer may be included in the adhesive composition, an optimum blend of properties may be obtained by use of 2 to 10% high molecular weight linear aliphatic hydrocarbon polymer by weight of the adhesive; amounts greater than about 20% by weight tend to lead to poorer extrusion in use at required temperatures.

An adhesive composition for use in a method according to the invention may be compounded to include additives normally used in hot melt lasting adhesives, for example colourants, fillers, resins and stabilisers.

A method according to the invention is especially beneficial in lasting both side portions of a shoe in a machine adapted to last the sides progressively by means of lasting roll means during relative movement of the lasting roll means and shoe lengthwise of the shoe, for example a No. 2 Automatic Side Lasting Machine supplied in the U.K. by The British United Shoe Machinery Company Limited (BUAL No. 2). In a method according to the invention, we prefer to last toe portions of the shoe using a hot melt adhesive composition based for example on a copolyester of terephthalic acid, isophthalic acid, aliphatic acid and diol consisting of or including 1.4 butane diol. Preferably this toe lasting is carried out before side lasting as aforesaid. Preferably, lasting of the shoe is completed by lasting the heel seat using another hot melt adhesive or tacks.

In order that the invention may become more clear there now follows a description of seventeen example hot melt adhesive compositions and their use in side lasting. Of these, example adhesive compositions 2 to 7, 10, 11, 12, 14 to 1 7 are selected for description to illustrate method aspects of the invention. It will be understood that these examples have been selected for description to facilitate understanding of the invention and not by way of limitation thereof.

Polyester materials (A to F) were prepared by controlled reaction of ingredients to produce copolyesters having acid units and diol units in the molar proportions shown in Table 1, and viscosity and softening point values, as shown in Table 1. Viscosity values recited in the Tables were determined by Brookfield Thermocell viscosity measurements. Polyesters A, E and F were made by controlled reaction of a charge of materials as follows. 236 grams of a liquid viscous dimerized linoleic acid of apparent molecular weight about 575 and comprising approximately 95% of dimer and 4% of trimer and 1 O/o monomer (Empol 1014 obtained from Unilever Emery) were mixed with 1070 grams of terephthalic acid and 270 grams of isophthalic acid. This mixture was reacted with 0.94 litres of 1,4 butane ciiol in the presence of 4.54 g of dibutyl tin oxide.Water and diol were boiled off, and in later stages of the reaction this was achieved under vacuum. Heating was continued and the temperature raised, to about 2400 C, to effect further polymerization of the polyester in the kettle until the polyester had the required viscosity.

Following production of the polyesters, various example adhesive compositions were prepared using materials in amounts by weight as shown in Table 2. Viscosity and softening point values of the compositions are also shown in Table 2. The resulting adhesive compositions were extruded into the form of a rod of 4 mm diameter for use as hot melt adhesives.

In these compositions, the aliphatic polymer used in each case was a high molecular weight linear aliphatic hydrocarbon polymer having a melt flow index in the range 5 to 200. The hydrocarbon polymer of "Aliphatic polymer compound 1" was Alkathene 17, a low density polyethylene having a melt flow index of 7 and a density of 0.917 g/cc. The material was added to the polyester as "Masterbatch 0120 White 005" comprising 70% by weight Alkathene 17, and 30% by weight titanium dioxide (anatase).

Thus the amounts of Alkathene 17 used in example adhesives 2, 3, 13, 14, and 1 7, are 70% of the values shown in Table 1, namely 5.8, 9.6, 3.5, 3.5 and 2.8 respectively.

"Aliphatic polymer compound 2" was Alkathene 17 per se; "Aliphatic polymer compound 3" was WVG23, a low density polyethylene having a melt flow index of 200 and density of 0.914 g/cc; "Aliphatic polymer compound 4" was "Masterbatch 0729 green 6420" comprising 62.5% by weight Alkathene 1 9, 1 5% titanium dioxide, 10% calcium carbonate, and yellow and green organic pigments. Thus, Alkathene 19 provides the hydrocarbon polymer of this compound (melt flow index 20, density 0.916 g/cc) and is present to an extent of 2.48% by weight of example composition 1 5.

"Aliphatic polymer compound 5" was "Masterbatch 0120 Brown 509" comprising 78% by weight Alkathene 1 7 and a mixture of iron oxide (20%) titanium dioxide (rutile) and carbon black. The amount of hydrocarbon polymer used was thus 3.12% by weight of the composition in example composition 16.

EXAMPLE 1 Method of lasting.

A man's shoe was lasted on a flat last as follows. An upper comprising a white vegetable tanned leather outer integument, and toe and heel stiffeners, was assembled on a last together with a Texon insole. The assembly was offered to the operating instrumentalities of a BUSMC No. 4A Pulling Over and Toe Lasting Machine to last toe portions of the upper. In this operation a hot melt adhesive composition substantially as example adhesive composition C was applied to the insole at a temperature of 2400C in a horseshoe pattern prior to inwiping of the lasting margin. After toe lasting, the shoe was offered to a BUAL No. 2 to last, simultaneously, both side portions of the upper.Example adhesive composition 16 was fed from a coiled rod (4 mm diameter rod) supply of the adhesive comppsition to a melting device of the machine and then applied to the shoe at about 2200C via nozzles at either side of the shoe. During operation, relative movement between the shoe and'lasting roll means of the machine occurred lengthwise of the shoe, and the nozzles were tracked along the shoe in a heelwards direction to progressively deposit a bead of hot melt adhesive along each side of the shoe, between the lasting margin of the upper and the insole in advance of the lasting roll means.The lasting roll means operated on the lasting margin of the upper progressively, as the'adhesive beads were applied to wipe the lasting margin across the insole and press it towards the insole and thus to deform the adhesive beads between the margin and insole and apply bonding pressure to the lasting margin.

This side lasting operation was completed in a matter of a few seconds, and consequently the time period during which bonding pressure was applied to the lasting margin at any particular point was minimal. After side lasting the shoe was presented to a BUSMC No. 5 Heel Seat Lasting Machine to tack last heel seat portions of the shoe. By inspection, the lasted shoe was found to be tightly lasted, with a clean firm feather and the lasting margin firmly bonded to the insole throughout.

EXAMPLE 2 Comparison of adhesive bonding ability of selected composition.

Example adhesive compositions 15, 1 6 and 17 were used in a BUAL No. 2 to side last simulated shoe uppers to insoles, using samples of various shoe making materials and Texon insoles. By way of comparison, a polyamide hot melt lasting adhesive sold in the U.K. by The British United Shoe Machinery Co. Ltd., as HM522 was also used to side last simulated shoes in the same way. An assessment was made of the sample bonds produced.

In making the simulated shoes, Texon insoles were used, and sections of upper materials of a shape and size to simulate each whole side of a shoe from the forepart portion to the seat portion were used. The lasts used were either "flat" and corresponding to men's shoes, or "high" and corresponding to ladies high heeled shoes. The sections of upper were secured to each other at heel and throat, and extreme toeward and heelward portions tacked to the insole on the last. This assembly was then presented to the machine in the manner of a shoe upper and insole assembled on a last. The machine was operated to apply the chosen hot melt adhesive at about 2200C progressively between the insole and lasting margin portions of the upper and to wipe the marginal portions of the upper across the insole and roll them with pressure towards the insole to effect lasting as above described.

The quality of the lasted portions was assessed as bad, poor, fair, good, or excellent in accordance with their appearance and resistance to manual deformation and pulling apart of the bonds along the length of the lasted portion. Samples assessed as bad or poor are regarded as unacceptable for shoe making purposes, whereas those assessed as fair are regarded as acceptable for shoe making and those assessed as good or excellent are regarded as even more acceptable. The results are shown in Table 3.

From Table 3 it will be seen that with example adhesive composition 16, results in tests with leather uppers were comparable with those using HM522 adhesive, whereas results in tests on other shoe making materials were noticeably better than with HM522. This is most apparent in relation to uppers with PVC linings, but can be seen also in bonds with black Porvair (Registered Trade Mark), blue PVC upper and fabric backer, and white vegetable tanned leather. The results also indicate that example adhesive compositions 1 5 and 1 7 performed in a similar fashion to example adhesive composition 1 6.

EXAMPLE 3 Variation of polyester and polymer.

Example compositions 1 to 14 were used to side last simulated shoe uppers in the manner described in Example 2 using flat lasts. It was found that example composition 1 was not capable of bonding "skinfit" lining material to Texon insoles, whereas example compositions 2, 3, 4, 5 and 6 were capable of bonding this material, although a lack of cohesive strength was noted in the skinfit. Example.

composition 7 was found to provide a good side lasting cement whereas composition 8 provided a brittle rod and was judged to lack adequate holding power for side lasting. Example adhesive composition 9 was not capable of holding down heavy leather or skinfit uppers. However, bonds of fair strength were achieved to these materials with example adhesive compositions 10 and 12 and to a lesser extent with example adhesive composition 11. Example adhesive composition 11 was difficult to handle in the machine and the adhesive application temperature was reduced to between 2000C and 21 50C in order to achieve a balance between flow rate of the adhesive (which was low at 200do) and holding power (which decreased above 21 50C). Example adhesive composition 13 was found to yield inadequate adhesion to the insole material and poor holding power. Example composition 14 was used at an adhesive application temperature of 205 to 2100C, and was found to give acceptable lasting of leather, Porvair, PVC, skinfit, polyurethane, and heavy leather to Texon insoles.

As will be apparent from the foregoing Examples, example adhesive compositions 2, 3, 4, 5, 6, 7, 10, 11, 12, 14, 15, 1 6 and 1 7 provided adequate side lasting of various upper materials in a machine adapted to progressively last both sides of a shoe simultaneously by means of lasting roll means during relative movement between the lasting roll means and the shoe lengthwise of the shoe.All these compositions comprised a minor amount of a high molecular weight linear aliphatic hydrocarbon polymer and a major amount of a substantially linear copolyester having a molecular chain made up of units corresponding to diol units and acid units derived from (a) one or more aliphatic diols; (b) terephthalic acid to an extent of not less than 60 mols per 100 mols of the acid units; and (c) one or more aliphatic or aromatic dicarboxylic acids including a dicarboxylic acid having a difunctional aliphatic hydrocarbon residue having not less than five carbon atoms in the molecular chain, the units being so selected that the adhesive composition has a softening point (Ball a Ring) in the range 120 to 2100C.

From the examples, it can be seen that better performance on a range of materials under the test conditions was achieved using those copolyesters having units derived from dimer acid in adhesive compositions having a viscosity at 2400C of about 900 to 1100 poise. Whilst some compositions using copolyester having units from sebacic acid (a dicarboxylic acid having an aliphatic hydrocarbon chain including 8 carbon atoms) are satisfactory, their performance does not appear to be as adequate as those using dimer acid to provide the aliphatic dicarboxylic acid units.

In contrast, example adhesive compositions 1, 8, 9 and 1 3 were found inadequate for side lasting in these tests. It is noted that example adhesive compositions 1 and 9 contain no high molecular weight linear aliphatic hydrocarbon polymer, whereas example adhesive compositions 8 and 1 3 use copolyesters D and C respectively. From Table 1 it can be seen that copolyester D contains no units derived from an aliphatic acid. Copolyester C contains units from adipic acid (a dicarboxylic acid having an aliphatic hydrocarbon chain including 4 carbon atoms) and polypropylene glycol neither of which is to be expected to be significantly compatible with the linear aliphatic hydrocarbon polymer.

TABLE 1 Polyester Formulations - Mole %

A B C D E F Acid units derived from Terephthalic acid 76 67.5 76.2 85.8 76 76 Isophthalic acid 19 22.6 17.0 14.2 19 19 Dimer acid 5 - - - 5 5 Sebacic acid - 9.9 - - - Adipic acid - - - 6.8 - - - Diol units derived from Butane diol 100 100 98.8 100 100 10û Polypropylene glycol - - 1.2 - - 2000MW.

Viscosity at 2400C 980 320 250 300 600 900 (poise) Softening point 190 174 190 205 190 190 (Ball & Ring) OC TABLE 2

Example Adhesive Ingredients 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 Polyester A 100 91.63 86.3 95.3 90.1 95.2 90.1 Polyester B 100 90 75 90 Polyester C 95.0 Polyester D 90.1 Polyester E 95 Polyester F 95 96 96 Aliphatic Polymer Compound 1 8.37 13.7 5.0 5 4.0 Compound 2 4.7 9.9 9.9 9.9 10 Compound 3 4.8 10 25 Compound 4 4.0 Compound 5 4.0 Viscosity at 240 C 980 1085 1170 1060 1260 985 980 300 320 350 725 380 250 600 1000 1025 1075 (poise) Softening point 191 191 191 191 191 191 191 205 174 176 178 173 190 190 191 191 191 (Ball & Ring) C TABLE 3

Adhesive Type of Last HM522 Example 15 Example Ia Example 17 Black Porvair Fair Excellent Excellent 21hmm Full chrome Flat Fair Fair Fair boardy leather 2mm Full chrome Flat Fair Fair Fair fleshy leather Upper having black Flat Bad Good Good Good PVC lining Upper having brown Flat Bad Good grained PVC lining Blue PVC upper with High Fair Good Good Good fabric backer White vegetable tanned Flat Good Excellent leather

Claims (14)

1. In a method of lasting a shoe in which marginal portions of a shoe upper are secured to an insole by an adhesive composition, the use of a hot melt adhesive comprising a minor amount of a high molecular weight linear aliphatic hydrocarbon polymer and a major amount of a substantially linear copolyester having a molecular chain made up of units corresponding to diol units and acid units derived from (a) one or more aliphatic diols; (b) terephthalic acid to an extent of not less than 60 mols per 100 mols of the acid units; and (c) one or more aliphatic or aromatic dicarboxylic acids including a dicarboxylic acid having a difunctional aliphatic hydrocarbon residue having not less than five carbon atoms in the molecular chain, the units being so selected that the adhesive composition has a softening point (Ball 8 Ring) in the range 1200Cto2100C.

2. A method according to Claim 1 wherein marginal portions of a shoe upper at the side of the shoe between the toe portion and the heel portion thereof are secured to the insole by use of an adhesive composition as specified in Claim 1.

3. A method according to Claim 2 wherein the side portions at opposite sides of the shoe are lasted simultaneously in a machine adapted to last the sides of the shoe progressively by means of lasting mllmeans during relative movement between the lasting roll means and shoe lengthwise of the shoe.

4. A method according to any one of the preceding claims wherein the adhesive composition is applied between marginal portions of the shoe upper and insole as a hot melt bead at a temperature between 2000C and 2200 C.

5. A method according to any one of the preceding claims wherein the adhesive composition has a softening point (Ball s Ring) in the range of 1 700C to 2000 C, and a viscosity at 2400C of about 900 to about 1100 poise.

6. A method according to any one of the preceding claims wherein the polyester has units consisting essentially of diol units derived from 1.4 butane diol, and acid units derived from dimerized fatty oil acid to an extent of from 2 to 20 moles per hundred moles of acid units present in the copolyester, and acid units derived from terephthalic acid and isophthalic acid to an extent of from 80 to 98 moles per hundred moles of the acid units of the copolyester.

7. A method according to Claim 6 wherein the terephthalic and isophthalic acid units together provide not less than about 95 moles per hundred moles of the acid units and the dimerized fatty oil acid units provide not more than about 5 moles per hundred moles of the acid units.

8. A method according to Claim 7 wherein units derived from terephthalic acid provide from 70 to 80 moles per hundred moles of the acid units and units derived from isophthalic acid provide from 15 to 25 moles per hundred moles of the acid units.

9. A method according to any one of the preceding claims wherein the high molecular weight linear aliphatic hydrocarbon polymer comprises a polyolefin having a melt flow index in the range 5 to 200.

10. A method according to Claim 10 wherein the polyolefin comprises low density polyethylene.

11. A method according to Claim 10 wherein the polyethylene has a melt flow index in the range 5 to 30.

12. A method according to any one of the preceding claims wherein the linear aliphatic hydrocarbon polymer is present to an extent of 1 to 20% by weight of the adhesive composition.

13. A method according to Claim 12 wherein the linear aliphatic hydrocarbon polymer is present to an extent of 2 to 10% by weight of the adhesive composition.

14. A method according to any one of the preceding claims wherein the hot melt adhesive composition is substantially as any one of example adhesive compositions 2, 3, 4, 5, 6, 7, 10, 11, 12, 14,15, 16 and 17.

1 5. A method of lasting a shoe substantially as hereinbefore described with reference to Example 1.

1 6. A shoe, side lasted by a method according to any one of the preceding claims.