Fabric tops are non limited to cotton ducks, black, white or brown. Today, forms and colourss of all descriptions in many of the new man-made fibres are now utilised. Gym shoes and casuals have gained widespread usage in the replacement of leather places non merely for summer wear, but for all seasons. The choice of last forms and breadths that are offered are similar to those of leather footwear. Orthopedic characteristics such as stiff back uping counters, steel shanks, and arch supports, combined with elation in weight and washability make them even more practical than leather for many utilizations, peculiarly in the field of adult females ‘s footwear where this type offers better protection than the thin soled, low slung concert dance type places.
In the waterproof and protective footwear field we have a similar variegation. The development of new polyesters and chemicals has enabled the industry to engineer their merchandises for diversion, concern wear and mundane life. The synthetics have produced footwear resistant to dissolvers, inactive snap, heat and visible radiation. A full rainbow of colourss are produced to run into the consumer demands for manner and public-service corporation.
One of the most recent developments in the footwear industry is the automatic traffic circle table gum elastic injection modeling machine. This procedure is a combination of injection and compaction casting.
At the beginning of each rhythm, the whole injection unit moves frontward axially, coercing the preheated compound through the nose. Simultaneously, the injection unit retracts so that a bed of compound is distributed over the length of the lasted shoe. The volume of compound
distributed in each portion of the mold pit is controlled by changing the velocity of abjuration. When the injection unit is sufficiently retracted, the exclusive cast is closed, and the clinch force per unit area is applied. The reciprocating screw so moves rearward, masticating the sum of compound required for the following rhythm, and the rotary tabular array moves the following station in forepart of the injection unit. The rhythm is from 2 to 5 proceedingss depending on the hardening temperature. Although this machine was developed for PVC, it is being used with a assortment of elastomeric compounds. The upper stuffs used include fabric, leather and plastic.
The best polymer for handmade footwear is still Hevea rubber because of its first-class green tack and thermoplastic quality. These belongingss are most of import since the lamination of parts is mostly affected with manus turn overing and a small plastic flow is needed to seal these articulations to do them waterproof.
Since most of the parts of gum elastic footwear are non molded, the surface of the stock as it is calendered must be free from all defects and must be compounded so as to retain calender stamping in the operations that follow. Proper polymer combinations and filler choice, along with the right balance of new gum to trash will keep this coating.
High cinnamene and other high runing point rosins, organic colourss, flock and some gas pedals are frequently master batched in order to better their scattering when added to the concluding mix.
A proper balance maintained between the remedy rate of the assorted parts of the shoe, peculiarly in heavy goods where there is a great fluctuation in thickness between upper and outsole. “ Started ” colloidal suspensions will ensue if this rate
is non proper.
The acceleration system must allow remedies at comparatively low temperature and yet non do searing at processing or storage temperature. Thiazole type gas pedals land themselves to footwear intensifying since they yield safe remedies with good tableland, Guanadines are effectual secondary gas pedals.
The fabrication of gum elastic footwear involves the usage of the same basic factory room equipment as in other gum elastic industries. Beyond this procedure nevertheless, there Is a battalion of operations such as cloth and gum elastic film editing, sewing, pre-cementing and adjustment of assorted upper innersole and outsole constituents. All of these parts in the assorted shoe sizes ( a scope by and large from a kid ‘s 2 to work forces ‘s 16 ) must get to the doing conveyer in proper sequence for the concluding assembly.
Upper compounds are by and large warmed up on provender Millss along with cutting bit. The ratio of new gum to trash is determined by the malleability demands of the stock. Certain parts, such as unlined uppers can digest really small bit, lest “ drooping ” take topographic point during vulcanisation. Soling stocks are warmed up on Millss or in a Banbury along with cutting room bit. All stocks are H2O cooled when calendered in order to obtain maximal shrinking before the film editing operation. If shrinking takes topographic point after the film editing operation, deformation would ensue. In order to retain both surface lucidity and tack, calendered upper stocks are run into knolls, beaded reels and bobbins. Smaller parts such as toe caps, heel pieces and gum corsets are cut utilizing a toggle imperativeness cutting method. These parts are so laminated to fiber carrying boards or are booked. Soling is calendered and cut into three or four pes lengths and stored on cleated plyboard or fibre boards in order to let it to shrivel wholly before cutting. Larger gum parts such as boot legs are cut by manus with a hot knife at the clip the rubberized liner cloth is laminated to it on a level conveyer. Heavy parts such as outsoles are by and large cut with a Wellman cutting machine.
This machine cuts a beveled border so that the sole will put at proper angle with the upper of the shoe with a lower limit of strain at the border. The colloidal suspensions are stored in particular cloth leaved books to forestall deformation and pressure. All of these engraved gum parts are by and large calendered on a ( 19 ” -30 ” ) four axial rotation inverted L type calender in which the beginning top engraved axial rotation is removable to let design alterations. Foxings, bindings and other strips are cut into proper breadth at the calender utilizing either a “ self-cut ” scratching axial rotation or conventional wheel knives decently spaced, and are boarded or booked. Colored chevrons are by and large laminated to foxings at this point besides. A 60 ” four axial rotation run alonging calender is by and large used to rubberise sheetings, ducks, cyberspace and fleece liners, clash coat cloths, and besides to sheet rag stock. Rag is a mixture of downgraded gum elastic stocks that are recompounded along with reclaim refined rubberized fabric bit and whiting. This stock is stiff and is used for counters and insole parts.
Some of the basic cloths used in footwear include, array, enameling, hosiery, boot and figure ducks, osnaburgs, drills and twills, sheetings, cyberspaces and fleeces.
Additionally in the cloth places, we use assorted prints, corduroys, suedes, and hopsacking stuffs cotton, nylonss, woollens, nylon, Dacron, sisal, hemp and many blends.
It is really of import that these stuffs be free frcm Cu and Mn and besides that they have optimal sums of sizing where required. Insufficient size in the backup cloths will do flabbiness and pursing when combined to the face cloth. An extra will do permanent furrows in the devising operation. An extra amylum in the face cloth will besides adversely affect the adhesion to the gum elastic foxing, etc.
The tennis upper cloths are “ combined ” utilizing SBR adhesive applied with a roller or physician blade and later laminated dry through a can dryer. Most uppers are two-ply although three-ply is besides used to some extent in the direct molded tennis shoe. The sum and type of sedimentation will find the manus of the upper. There must be a balance between adhesion and “ breathability. ”
The face cloths must be checked for wettability, carbon black opposition hemorrhage, washablity and adhesion. Some of these lacks can be compensated for by alteration of flim-flaming latex. Others like shed blooding crocking and shrinking can be remedied merely by the cloth closer Color stableness in vulcanising must be predetermined. Certain cloths and plaits can non be vulcanized in an ammonia remedy. Others may necessitate lower than normal temperature.
Unlike rainproof uppers, tennis cloths are plied up on a film editing tabular array, by and large 24 plies, 12 face down, 12 face up. These are cut with dual arm clicker die imperativenesss so that each cut will bring forth 12 brace cuts. The cutting bit is ground into flock for usage as a stiffener in shred compounds.
Cements and Latexs
Most gum elastic parts in both waterproof and term footwear are cemented at the calendaring operation with gum elastic cement. This cement is normally sheet gum elastic compounded with tackifiers and remedies, and dissolved rubber dissolver. Tennis tops are machine cemented lasting. Lasted tennis places are dipped into compounded gum elastic latex to organize a base on which to adhere the parts. Colo pigments, remedies, tackifiers and agents are used to obtain good adhesion and visual aspect.
Places geting at the terminal of the devising line are loaded onto monorai vulcaniser autos which are rolled into topographic point after concluding review of the remedy rhythm.
Remedy rhythms will change from 45 proceedingss to 1.5 hours depending on the type of footwear and the efficiency of the vulcaniser. In all instances 20 to 30 pound. of tight air is introduced to forestall blister formation from air entrapped between parts and besides within heavy gum elastic portion blowers circulate the air to minimise cold musca volitanss.
On heavy points like boots, a vacuity remedy is run where air force per unit area is reduced inside the boot in order to compact parts and minimise the happening of pin holes at the seams.
If ammonia is to be used, three to five lbs of anhydrous ammonium hydroxide is injected after the air has been introduced. Bring arounding temperatures used vary from 260F to 300F. Ammonia remedy produces a calendered tack free surface.
The advantage of “ air ” remedies is that less pigmentation is required peculiarly for white compounds, as the ammonium hydroxide has a yellowin consequence. Places cured in this mode are somewhat tacky to the touch. Multicolor plaits and cloths are frequently cured in air to retain brightness peculiarly if one or more of the colourss react adversely with the ammonium hydroxide.
Man-made UpperUpper CompoundNatsyn80Air Dried sheets80Solprene 120520SBR 100920Hard Clay60Whiting60Whiting60Hard Clay60Light Process Oil13Pepton 220.25Velsicol X-306Process Oil15Zinc Oxide5Velsicol X-305Stearic Acid0.6Zinc Oxide5Anthicheck Wax0.15Stearic Acid0.5AGERITE SUPERLITE0.25Anthicheck Wax0.16DOTG0.5AGERITE SUPERLITE0.25ALTAX0.9DOTG0.5Sulfur2.15ALTAX1.0Sulfur2.25Total248.55Total249.91Sp.gr1.43Sp.gr
Brown Crepe SBR 1009
Hard Clay Pepton 22 Process Oil Velsicol X-30 Zinc Oxide Stearic Acid Retarder
85 0 5 3
3 6 6
Masterbatch ( 50 % )
25 20 85 80 15 10
Top Grade Molded Sole
Brown Crepe SBR 1703 Solprene 1205 Hard Clay Silene EF
Press Scrap ( Ground )
70 25 10 80 25 30
0.15 16 10
SBR 1507 Hi Sil 215
Diethylene Glycol Light Process Oil
Zinc Oxide Stearic Acid AGERITE SUPERLITE Retarder CAPTAX
METHYL ZIMATE Sulfur
Air Dried Sheets 100.00
Pepton 22 0.30
Rosin K 5.00
Zinc Oxide 10.00
AGERITE SUPERLITE 0.20
Pine Tar 1.00
( Dissolve in Rubber
so vent )
Sols and Heels
The last decennary has witnessed radical proficient alterations in the shoe industry. A consequence of this has been a gradual but relentless lessening in the production of old manner conventional sole and heels.
Sole and heel manufacturers, nevertheless, have non lost place as a consequence of this. Annual tunnage of their merchandises has increased well due to the inventiveness of chemists and applied scientists in developing new stuffs and procedures.
Today non-leather colloidal suspensions account for good over 70 per cent of shoe undersides, as compared to 60 per centum a decennary ago. This progressively high degree of credence has been reached non merely through demonstrated better service and comfort, but besides through improved finished merchandise entreaty, a factor so indispensable harmonizing to current selling criterions.
This steadily increasing credence of other than leather shoe undersides indicates clearly how good the sole and heel industry has met challenge of these basic technological alterations. The most of import of these that need some amplification are as follows:
Direct Molded Footwear
Unisoles – Nuclear and Polyvinyl Chloride
Printed Soling Sheets
Micro-Cellular Soling-Cushion-type and Firm ( LeatherAlike )
A. Direct Molded Footwear ( DMF )
This procedure involves the casting of gum elastic colloidal suspensions and heels straight to the shoe upper. Conceived in the early 1900 ‘s in Germany direct molded or cured footwear did non make existent production proportions until the depression of the 30s in Europe – in the United States in the mid ’50 ‘s.
DMF production continues to demo one-year additions, in adult females ‘s casuals, tennis, hoops places and gym shoes. Besides to some grade this procedure has been adopted by the U.S. Army.
Efficient, economical operation of expensive DMF equipment demands much faster bring arounding rhythms than conventional colloidal suspensions and heel. In add-on to supplying rhythms of two proceedingss at 300 F. DMF compounds must be fast and free-flowing, without any incipient singe which would prevent a strong lasting bond to the shoe upper.
Fast remedies are obtained by a wise combination of ALTAX and METHYL or ETHYL 21 MATE, or AMAX, CAPTAX and UNADS. Free fluxing compounds require broad sums of oils and plastizers, such as light procedure oil, REOGEN and PLASTOGEN.
This is the term given to integrally-molded sole and heel combinations made in exact sizes and breadths, one time this unit is cemented to the shoe upper, it is ready for the shoe box, which eliminates many labour stairss of coating, heel attaching, inking, etc. , for the shoe maker.
Since these colloidal suspensions have to hold the same “ massiveness ” or estimate on the border as the sole, plus floging, of a stitched shoe they besides result in a longer waring underside. This means a higher quality shoe at lower cost, a tough combination to crush.
Unisoles, produced out of both rubber-resin compounds and polyvinyl chloride have been extremely successful in juvenile places, and in work forces ‘s places to a lesser grade.
Unisoles have become a extremely important, lasting fixture in the shoe industry, replacing a big sum of conventional colloidal suspensions and heels.
C. Printed Soling Sheets
Over the old ages, with steadily increasing labour costs in the sole and heel industry, there has been a tendency to soling sheets instead than separately molded colloidal suspensions, in the dilutant guages.
Since adult females ‘s places constitute over 50 % of shoe production and since colloidal suspensions for adult females ‘s places are thin-gauge, this has meant a steadily increasing production of soling sheets.
Within the past few old ages, soling sheets, printed to give the visual aspect of a top-quality leather sole, have been imported from Germany. Acceptance by shoe makers was immediate and exclusive and heel makers procured equipment to double these types of coatings.
The soling sheets are foremost printed pith rotogravur
axial rotations engraved to give a leather like form. In a uninterrupted procedure, the sheet is so covered with a clear movie of greatcoat which can be formulated to give assorted degrees of rubric. The greatcoat is normally urethane or epoxy rosin, which, when cured, makes the prints imperviable to cleaning dissolvers used in the shoe mill.
This pre-finishing of soling sheets consequences in significant nest eggs to the shoe maker, since the excess cost to engage for the pre-finished soling sheet is well less than his ain cost of completing the undersides. The shoe maker besides ends up with a uniform, more pleasing visual aspect on his shoe undersides.
DA» Micro-Cellular Soling, Soft ( Cushion-Like ) and Firm
( Leather-like )
This type soling was foremost produced in the early ’50 ‘s and gained immediate credence. Used in heavier gages, this Micro-Cellular Soling gave a soft, cushiony, resilient walk to places of all types.
It was foremost predicted to be a more or less cyclical merchandise but alternatively has become a lasting fixture it titling of places. It is estimated that 15 % of all manufactured today carry these soft Micro-Cellular Soles.
Initially, this type soling was made merely in sheet signifier but late it has been produced in the heavier gages in integrally molded sole and heel combinations which have become really popular on work forces ‘s hunting and work boots.
This integrally shaped shank consequence consequences in a absolutely level underside normally with a rib design.
These colloidal suspensions are initally cured in design casts followed by oven intervention to extinguish residuary shrinking. Sols are so die-cut to a standard size.
Firm ( Leather-Like ) Micro-Cellular Soling
This type of soling has been a recent development in soling sheet and has been hastened by the desire of the shoe maker for lighter weight in his shoe underside.
Whereas the soft, shock absorber type is expanded to specific gravitation of less than.70, the house type is merely partly expanded to a specific gravitation scope of 0.9 to 1.10.
There has been considerable use of this house cellular soling to day of the month, and it is predicted that it will go on to turn.
^ ” philippic e**i
SBR 1507 ~ _ N M Black
SBR 177S 50
WH Tire Reelain – 40
Black MB 1805 17
Zinc Oxide 11
Zeo 45 * 3
DIXIE CLAY ” 85
Mapico Red 3 40
HAF Black 50
Stearic Acid ”
Resinex 100 REOGEN
Panarez 6-210 15 — –
AGERITE RESIN D 11
Light Process Oil 12 10
ALTAX 2 1.75
DOTC 1.50 1
Sulfur 2:50 ______2.50
“ ” Entire ~7 ^216.50 281.25