WO2003000810A1

WO2003000810A1 - An improved impregnating / coating composition and a composite incorporating the composition

Info

Publication number: WO2003000810A1
Application number: PCT/IN2002/000136
Authority: WO
Inventors: Raman Aroon; Krishnappa Natesh Gubbi; Nagaraju Satheesh Kumar Maddur; Manjunatha Nanjundaswamy; Narasimha Murthy Ganesh Maduvanakodi; Krishna Krishna
Original assignee: Raman Boards Ltd
Priority date: 2001-06-25
Filing date: 2002-06-24
Publication date: 2003-01-03

Abstract

The invention disclosed in this application relates to an improved impregnation or coating composition useful for variety of applications, which comprises polymer(s)/polymer emulsions/latex normally employed for such applications and ash from the vegetable origin such as husk and other ashes like fly ash, or a mixture thereof .The ash used in the composition is selected from rice husk ash, coffee husk ash, ground nut husk ash etc and other ash like fly ash etc . The invention also relates to an improved process for the preparation of a composite useful for variety of applications which comprises: impregnating or coating a substrate with the above said composition and drying the treated substrate. In addition the invention also provides a shoe made by using the above composite This composition can also be added to paints and other coating compositions.

Description

AN IMPROVED IMPREGNATING/COATING COMPOSITION AND A COMPOSITE INCORPORATING THE COMPOSITION

The present invention relates to an improved impregnating or coating composition, a composite prepared from the said composition and a shoe incorporating the composite. The composition of the present invention has varieties of applications. For example the composition of the present invention is useful for applications like insoles, shoe stifϊeners etc, in paints, coatings and the like. The composition of the present invention contains ash from vegetable origin such as rice husk ash, coffee husk ash groundnut husk ash, fly ash etc, or their mixtures. The composition also contains carbohydrates. The use of these waste materials in the above said composition results in making the composition not only cheap but also eliminates the hazards caused by their disposal as landfill consequently avoiding environmental pollution. In addition there is value addition to these materials which otherwise are waste materials.

The invention also relates to an improved process for preparing the composition as well as an improved process for preparing a composite useful for application as insoles and stifFeners from the said composition and a shoe incorporating the said composite. This composition can also be added to the paints and other coating compositions.

Most footwear frequently uses reinforcing materials for the purpose of shape retention and comfort. Such materials include stiffener materials such as toe puff materials, which are used to keep the shape of the toe area of the shoe and counters that are used to keep the shape of the heel area. Additionally, these materials are also used as heel liners and insole materials in footwear. The toe puff and counters are mostly thermoplastic while the insoles are either a composite of paper or textile materials. Such materials mainly contain resins or polymers with fillers as part of their impregnating compositioa The above said non-renewable materials are very costly. The ash from vegetable origin such as rice husk ash, coffee seed ash, ground nut husk ash etc., are generally viewed as having little, if any, commercial value in their raw material form. The ash from vegetable origin such as rice husk ash, coffee husk ash, ground nut husk ash etc, which are generated when their husk are used as a fuel in industry and coal which is used in large quantities in large power generating stations, are generally a discarded waste product. It is also well known that huge amount of money is being spent for their safe disposal. The ash that is carried by wind is a major cause of concern as it is damaging the environment and water tanks. India produces around 80 million tons of Paddy annually and milling of the paddy generates around 22million tons of husk, which on combustion produces over 5.0 million tons of ash. These ashes are high volume material and require large space for disposal. It is known, however, that rice husk material typically contain a substantial amount, typically about 16 to 20 percent, of silica (SiO2) and when burned yield an ash, which is rich in amorphous silica. Most ashes, to a certain extent rice husk ash is used as an industrial raw material in the ceramic, cement and metallurgical industries. The Rice husk used as a fuel has a calorific value of around 3500 Kcal kg. The problem of disposal of ash is highly difficult, as it is black in color, light in weight and easily carried by wind and water contributing to air and water pollution. The inhaling of rice husk ash can cause silicosis characterized by diffuse interstitial fibrosis and nodules.

Therefore, the effective utilization of these wasteful ashes are important in a view of not only protecting the environment and other resources from pollution but also for the purpose of value addition to ash, otherwise categorized as waste. This ash referred to herein as " ash from vegetable origin " is viewed as a filler material capable of replacing or extending the more expensive ingredients of the composition.

The use of filler in compositions for impregnating or coating of fabric for stiffener applications is a matter very well known in the prior art. The normally used fillers for the above purpose are calcium carbonate, china clay, Titanium dioxide, talc, etc. These fillers are much expensive than the filler like ash. The table below gives an approximate cost of fillers used in similar compositions. SL.NO FILLER NAME PRICE RANGE In US $ / kg

1 Calcium Carbonate 0.12 to 0.24

2 China clay 0.06 to 0.2

3 Talc 0.06 to 0.3

4 Ash from vegetable origin 0(available free as it is a waste material )

In technology employing ash from vegetable origin like husk ash, the fundamental conventional thinking has been:

(1) to consider the husk as a heat source and

(2) to try to find practical & commercial uses for the resulting ash.

When ash from vegetable origin like rice husk is used as a heat source it is necessary to blow air into the husk after it is lit so as to achieve the highest combustion temperature possible. However, almost all of the husk ash obtained by such high-temperature burning is crystalline, very low in chemical activity arid black in color. It therefore has few practical uses. When air is blown into to the husk for burning it at high temperature, the resulting rice husk ash progressively crystallizes a fact that can be readily confirmed from the X-ray diffraction pattern of the rice husk ash. It has been known that silica, along with calcium oxides, is a component of Portland cement, primarily occurring as complex calcium silicates. However, the silica produced by the incineration of silica containing organic agricultural materials can be used as a cement component only to the extent that it replaces sand or shale, because the incineration of the hulls inevitably leads to the production of ash containing crystalline forms of silica. Fly ash is waste by product of large-scale coal fueled power generation plants. The chemical composition of the f y ash depends upon the coal source, the manner in which the coal is burnt and the collection method. Therefore the properties of fly ash are a function of the composition of the coal, the particle size of the fly ash and the temperature of combustion. Based on the above criteria, generally the fly ash is classified into two major types namely Class C and Class F type

The prior art compositions for the applications like shoe insoles, shoe stiffeners, paints and coatings employs mainly polystyrene, styrene acrylate emulsions, polystyrene— acrylic, polyvinyl acetate emulsions mixed with plasticisers, fillers, stabilizers, colorants, along with others polymer emulsions like styrene-butadiene rubber latex, natural rubber latex etc. These compositions are used for impregnating and coating on variety of substrates like woven cloth of cotton or synthetics and non-woven substrates.

US patent number 4507357, dated March 26, 1985, discloses the use of an amino resin for improved stiffness and creep resistance. US Patent number 935001 describes a sintered stiffening material which attains stiffness upon heating or when dipped in solvent. It is to be noted that the both the above patents do not address the use of an other wise a waste material like husk ash, fly ash etc. Attempts to utilize fly ash have been made as disclosed in U.S. Pat. No. 4,088,804 where fly ash is added to cement compositions to react with the calcium hydroxide produced during the curing of the cement. Additionally, U.S. Pat. No. 4,425,440 disclose that fly ash can be employed to form a thermally insulating material and a flame retardant thermal insulation and U.S. Pat. No. 4,229,329 discloses the use of fly ash to prepare a fire retardant coating composition useful as paints or mastics. . US Patent 4714722 discloses a method for accelerating the dehydration of an aqueous polymeric dispersion composition comprising polymeric particles and mineral filler dispersed in an aqueous medium and improving bonding of the solids contained therein, the method consisting essentially of adding Class C fly ash as the sole water-reducing agent to said composition in an amount sufficient to significantly reduce the dehydration time of said composition compared to compositions which are identical save for the absence of Class C fly ash.

It is to be noted that the all the above disclosures are specific to any one particular ash type. All prior art processes hitherto known for impregnating substrates for use in insoles and stiffening applications use the synthetic polymer and mineral fillers referred to above. The processes employing these materials are not only costly but also is not eco friendly.

Therefore the main objective of the present invention is to provide an improved " composition useful for impregnating substrate useful for insoles and stiffening applications.

Another objective of the present invention is to provide an improved composition useful for impregnating substrate useful for insoles and stiffening applications which contains ash of vegetable origin such as rice husk ash, coffee husk ash , ground nut husk ash etc and fly ash or their mixtures.

Yet another objective of the present invention is to provide an improved composition useful for impregnating process useful for insoles and stiffening applications, paints and other coating compositions etc. which contains, in addition to the above said ash, carbohydrates. Another objective of the present invention is to provide an improved composition useful for impregnating process useful for insoles and stiffening applications, paints and other coating compositions etc. which is cheap and biodegradable and ecofriendly.

Still another objective of the present invention is to provide an improved composition useful for paints & surface coatings.

Yet another objective of the present invention is to provide an improved process for the preparation of the composition useful for impregnating substrate which is useful for insoles and stiffening applications

Still another objective of the present invention is to provide an improved process for the preparation of a composite which is useful for insoles and stiffening applications employing the above said composition.

Yet another objective of the present invention is to provide a shoe incorporating the composite.

In our sustained effort to improve the composition useful for impregnating substrate which are useful in insole and stiffener applications we observed that incorporation of ash of vegetable origin such as rice husk ash, coffee husk ash ground nut husk ash etc fly ash etc or their mixtures to the impregnating composition has a unique effect. Further more we have also observed that additional incorporation of carbohydrates to the above said composition further enhances the characteristics like, flexibility and stiffness, toughness, retention of shape, improved biodegradability, etc. We have also observed that there has been neither any general or patent literature stating the use of an impregnating or paint/coating composition containing such an ash. In other words, there is no prior art regarding a composition containing the above mentioned ashes or their mixtures and carbohydrates for the above said applications._. The composition containing ash or its mixtures with or without carbohydrates make the composition and the process of impregnating a substrate or a paint/coating composition not only cheap but also utilizes a material which has a disposal problem and causing pollution.

The ash from the vegetable origin such as husk and other ashes like fly ash, etc., employed in the composition of the present invention are very cheap and abundantly available making the resulting composition is also cheap. The performance of the composition of the present invention is also comparable with the present day available composition for the same purpose. The use of waste ash also solves the acute problem of disposing them off and problems connected with pollution.

Accordingly the present invention provides an improved impregnation or coating composition useful for variety of applications, which comprises ρolymer(s)/polymer emulsions/latex normally employed for such applications and ash from the vegetable origin such as husk and other ashes like fly ash, or a mixture thereof

The ash or its mixtures which may be employed in the composition may be selected from rice husk ash, coffee husk ash, ground nut husk ash etc and other ashes like fly ash etc. The composition may also contain carbohydrates such as cornstarch, dextrin, pre-gelatinized starch, tapioca starch, potato starch or their mixtures.

In a preferred embodiment of the invention, the composition comprises the polymer(s)/polymer emulsions/latex in an amount in the range of 50 to 90 % by weight of the composition and a ash or its mixtures thereof in an amount in the range of 10 to 50 % by weight of the total composition.

In yet another embodiment of the invention the amount of carbohydrate or its mixtures employed may range from 0.1 to 25% by weight of the composition.

The invention also contemplates an improved process for impregnating a composite using the composition of the invention.

The invention is particularly applicable to prepare composite which is useful for insoles and stiffener applications in addition to surface coatings, paints etc.

Accordingly the invention provides an improved process for preparing a composite useful for insoles and stiffener applications which comprises impregnating or coating by conventional methods a substrate in a composition containing polymer(s), polymer emulsion(s) or latex and ash from the vegetable origin such as husk and other ashes like fly ash, or a mixture thereof, drying the treated substrate and cooling to room temperature.

The substrate employed for coating / impregnation may be selected from any flat, flexible and porous material which are known in the art, which are used for insoles and stiffening applications such as wet laid fibre mat, a needle punched non- woven felt and the like polyester non woven fabric, jute woven or non woven.

In a preferred embodiment of the present invention the polymers which may be used in the composition and the process for impregnation may be selected from a wide range of natural and synthetic latexes, homo polymers and copolymers of acrylic, styrene, styrene-acrylate, vinyl acetate, carboxylated monomers, ethylene, butadiene and its derivatives.

The amount of polymer(s) present in the composition used in the process may be in an amount in the range of 50 to 90 % by weight of the composition, preferably the amount of the polymers may range from 60 to 80% by weight of the total composition.

The ash which may be used in the composition and the process for impregnation may be selected from rice husk ash, coffee husk ash, ground nut husk ash, fly ash etc. or the mixtures thereof. The amount employed may preferably range from 10% to 50% of the total composition. The amount of ash or its mixtures thereof may be present, preferably, in the range of 10 to 30 % by weight of the composition.

The composition may also contain additionally other fillers like calcium carbonate (of type precipitated or mineral), china clay, talc, Aluminium silicate vegetable seed powders like tamarind kernel powder, coconut shell powder etc. The amount of such fillers when present may range from 0.1 % to 30%, preferably from 1% to 20%. by weight of the total weight of the composition.

The type and amount of polymer content in the composition of the present invention depends on the application and levels of performances required. The impregnating composition used for impregnating substrates for applications like cellulose insole board etc , which undergoes repeated flexing and which is also directly exposed to sweat generated by the feet, may mainly be a composition which has a relatively low Tg and which is soft and elastomeric as compared to that of a shoe stiffener application which is stiff and more thermoplastic in nature. The thermoplastic composition which has the tendency to soften upon heating requires a softening temperature less than 100 Deg. C but higher than ambient as it is required to take the final shape of the last (shoe making mold) so as not to soften while in service. A Tg of above 45 Deg. C is preferred and more preferably above 55 Deg. C. Typical styrene- acrylate copolymer emulsion may comprise of styrene content of 50 to 80 % and more preferably 60 to 70 % and remaining portion largely by acrylic monomer base like butyl acrylate with other ingredients required to carry out emulsion polymerization and such non monomeric additives are generally present at less than 10% of the total mass.

The compositions used for impregnating substrates useful for insole applications are elastomeric in nature and relatively non-thermoplastic (which does not soften upon application of heat) and are highly flexible and tough in nature, could be a blend of natural rubber latex with or without styrene acrylate latex of similar configuration detailed above with a carbohydrate of the current invention. The natural rubber latex in the composition can be present in the range of 20 to 80% of the total composition with a styrene-acrylate copolymer latex from 0.1 to 40% and a carbohydrate like starch of corn or tapioca base

The composition useful in the process of the present invention may also contain processing aids like plasticisers, surfactants, dispersing agents, anti settling agents, buffers, biocides and cross linkers which are normally employed in such compositions The amount and the type of such agents depend on the quality of the end product required. Usually their amount when present in the composition may range from 0.1 % to 30% by weight, preferably from 0.5% to 15% by weight of the composition

The process used for the preparation of the composition of the present invention involves conventional methods such as mixing the type and amount of individual ingredient by putting in a mixing vessel fitted with a mechanical type agitator. The ingredients are added starting from a polymer emulsion and the ash or its mixtures with or without carbohydrate(s) and then if desired other additives. It is recommended to add the ash and carbohydrates (powder inputs ) by dispersing or dissolving in water for easy and better mixing. The time and speed of stirring is decided depending on the stability and type of the composition and is one of the critical factors for the consistent performance of the composition.

The fibers in the wet laid fibre mat may include virgin fibers with substantial amounts of secondary fibers or non-woven of type spun bounded, needle punched, stitch bonded and other type, which are commonly employed in the prior art. The substrate depending on the application may include a scrim, which helps in attaining the high strength with low stretch required in strobel applications.

The process of impregnation, according to the present invention, may be those

I employed conventionally. The impregnation may accordingly effected by dipping the material in the composition. Drying may be effected by hot air dryer, drying cans etc. The range of drying temperature may vary depending upon the type of composition employed and its characteristics like film forming temperature, Tg, minimum cross linking temperature etc. The temperature generally varies from 80 to 190 degree C, more commonly 120 Deg. C to 160 Deg. C. The ratio of the substrate to the composition is again performance related and usually varies between 1:0.1 to 1:6.0 , most usually 1:0.3 for insoles of wet laid fibre mat type and 1:2 for fibre mats of non wet laid type which are usually meant for shoe stiffeners application. The composite obtained if desired may be is treated with an insolubliser such as Glyoxal and dried again and cooled to room temperature. The composite may be wound after drying and is either directly cut into sheets of required size or carried further for applications like hot melt adhesive coating and coating of other surface active materials The resultant product is found to be similar in performance compared to a conventional product.

The details of the invention are given in the examples given below which are provided only for illustration purposes only and therefore should not be construed to limit the scope of the invention.

EXAMPLE 1

Preparation of binder composition containing rice husk ash

Preparation of rice husk ash slurry:

In order to aid convenient mixing of the rice husk ash in the binder composition, the ash is made into a form of slurry by dry grinding the ash in a domestic mixer and sieved to get a powder having a particle size of 75 microns.

100 gm of rice husk ash made as above is mixed with 223 gm of water and i 0.5gm of dispersing aid (Pidisper 6240, manufactured by Pidilite Industries

Limited, Mumbai, India ) in a domestic wet grinder to get a fine slurry of ash.

The slurry found to have a final solids content of 30.9%.

Binder composition: 96.7g of the slurry prepared as described above is mixed with 140g of styrene acrylate copolymer emulsion (having solids content of 50%) in a glass beaker and stirred using a mechanical stirrer.

EXAMPLE 2

A needle punched polyester non-woven fabric having a weight per square meter 150gm is impregnated by dipping the fabric at room temperature in the composition prepared as described in the example 1 and the pick-up is adjusted by passing through a squeeze roll to obtain the fabric to composition ratio of 1 : 2 on dry to dry basis. The above impregnated non woven fabric is dried in a hot air oven at temperature maintained at 150 Deg. C and for a period of 20 minutes and is then passed through a laboratory calendar to get a composite having a finish thickness of 1.2mm.

In the Table 1 we are giving the comparison of a composite made by prior art using a needle punched polyester non woven fabric and the composite made as per the example 2.

Table 1

Properties Unit Control * Examplel compositel composite

Thickness mm 1.09 1.1

Density gm/cc 0.43 0.41

1

Dome hardness Newton 73 74

* Control composite 1 is the one which is made by using a binder composition in which the ash is not used and instead calcium carbonate is used. It can be concluded from the above table that the performance of the ash containing composition is at par in terms of functional properties to that of prior art composition.

EXAMPLE 3

This example provides details for making a shoe stiffener composite using a cheap biodegradable jute non- woven. The impregnating composition containing the rice husk ash slurry prepared as described in example 1 is used in this example also.

A needle punched jute non-woven fabric having a weight per square meter 200gsm is impregnated by dipping the fabric in the composition prepared by the process described in examplel and the pick up is adjusted by passing through a squeeze roll such that the fabric to composition ratio is 1: 2.5 on dry to dry basis. The above impregnated non woven fabric is dried in a hot air oven at temperature maintained at 130 Deg. C for a period of 25 minutes and is then passed through a laboratory calendar to get a composite having a finish thickness of 1.2mm. In the Table 2 given below is the comparison of a composite made by prior art using a needle punched jute fibre composite made as per the example 3.

Table 2

Properties unit Control * Example2 composite2 composite

Thickness mm 1.09 1.15

Density gm/cc 0.39 0.4

Dome hardness Newton 74 73

* Control composite2 is the one which is made by using a binder composition in which the ash is not used and instead calcium carbonate is used. It can be concluded from the above table that the performance of the ash containing composition is at par in terms of functional properties to that of prior art composition.

EXAMPLE 4

Preparation of rice husk ash & fly ash slurry

In order to prepare a binder composition containing rice husk ash & fly ash, the mixture of ashes is made into slurry, by dry grinding the equal quantities of rice husk ash & fly ash in a domestic mixer at room temperature and sieved to get a powder having a particle size of 100 microns. 100 g of the ash made as above is mixed with 150 g of water and 0.75gm of dispersing aid (Pidisper 6240, manufactured by Pidilite Industries Limited, Mumbai) in a domestic wet grinder to get a fine slurry of ash. The slurry found to have a final solids content of 40%. Binder composition

To the 140 g of 50% solids styrene acrylic copolymer latex having a styrene content of 70 %, butyl acryl ate content of 30%, 75g of 40% solids slurry of rice husk and fly ash obtained as described above is added under constant stirring using a mechanical stirrer. A polyester non woven fabric having a weight of 150g/sq.m (generally referred to as gsm )is dipped in the above mentioned composition at room temperature . The excess pick up by the fabric is removed by passing through squeezing rolls to get a final dry weight of 45 Og. The resultant fabric is dried in a hot air oven at a temperature of 150 degree C for 20 minutes and then passed through a calendar to get a final thickness of 1.00 mm. The final composite had good stiffness and sufficient tack developed upon dipping in a solvent like toluene EXAMPLE 5 Preparation of a composite using rice husk ash and fly ash slurry & carbohydrate

In order to aid convenient niixing of the rice husk ash in the binder composition, the ash is made into a form of slurry by dry grinding the ash in a domestic mixer and sieved to get a powder having a particle size of 75 microns. lOOg of rice husk ash made as above is mixed with 122g of water and 0.5g of dispersing aid (Pidisper 6240, manufactured by Pidilite Industries Limited, Mumbai, India) in a domestic wet grinder to get a fine slurry of ash. The slurry found to have a final solids content of 45%. In order to aid convenient mixing of the fly ash in the binder composition, the fly ash is made into a form of fine powder by dry grinding the ash in a domestic mixer and sieved to get a powder having a particle size of 100 microns. 100 gm of the fly ash made as above is mixed with 100 g of water and 0.75 g of dispersing aid (Pidisper 6240, manufactured by Pidilite Industries Limited, Mumbai) in a domestic wet grinder to get a fine slurry of ash. The slurry found to have a final solids content of 50%.

The following composition was prepared as described below Styrene Acrylic copolymer latex 50%solidscontent 50parts Rice husk ash slurry 45% solids content 20 parts

Fly ash slurry 50 % solids content 10 parts

Corn starch 90 % solids content 20 parts

And water to make a final solid content of 50%. The corn starch is added to the Styrene Acrylic copolymer latex under stirring taking care that no lumps are formed. Then the rice husk slurry is added followed by the addition of fly ash slurry. A Needle punched non woven fabric having a weight per sq m of 200g is dipped in the binder composition prepared as described above the excess pick up of the fabric is removed by passing through a squeeze rolls and the pick up is adjusted to get a final dry weight of 600 g. It is then dried in hot oven at a temperature of 140 degree C for about 25 minutes and passed through a calendar roll to get a final thickness of 1.4mm. The resultant composite is found to have good stiffness and satisfactory levels of tack developed upon dipping in a solvent like toluene. The composite is also found to have good thermoplasticity to mould the component with normal conditions used in counter molding of the shoe.

EXAMPLE 6 Preparation of a composite using rice husk ash slurry & carbohydrate: In order to aid convenient mixing of the rice husk ash in the binder composition, the rice husk ash is made into a form of fine powder by dry grinding the rice husk ash in a domestic mixer and sieved to get a powder having a particle size of 75 microns. lOOg of rice husk ash made as above is mixed with 122g of water and 0.5g of dispersing aid (Pidisper 6240, manufactured by Pidilite Industries Limited, Mumbai, India ) in a domestic wet grinder to get a fine slurry of ash. The slurry found to have a final solids content of 45%. The following composition was prepared as described below Styrene Acrylic copolymer latex 50% solids content 60parts

Rice husk ash slurry 45% solids content 20 parts Tapioca starch 90 % solids content 20 parts

And water to make a final solid content of 44%

The tapioca starch is added to the Styrene Acrylic copolymer latex under stirring taking care that no lumps are formed. Then the rice husk ash slurry is

I added. In the resultant composition the Styrene Acrylic copolymer latex had a styrene content of 70 % and butyl acrylate content 30%. A needle punched polyester non woven fabric having a weight of 150 gsm is dipped in the binder composition prepared as described above at room temperature . The excess pick up in the fabric is removed by passing through a squeeze rolls and is adjusted to get a final dry weight of 450g. It is then dried in hot oven at a temperature of 150 degree C for about 20 minutes and passed through a calendar roll to get a final thickness of 1.2mm. The resultant composite is found to have good stiffness and satisfactory levels of tack developed upon dipping in a solvent like toluene.

EXAMPLE 7 Preparation of a composite containing fly ash slurry & carbohydrate

In order to prepare a binder composition containing fly ash slurry, the fly ash is made into a powder by dry grinding the ash in a domestic mixer at room temperature and sieved to get a powder having a particle size of 75 microns. 150 g of the fly ash made as above is mixed with 150 g of water and 0.75gm of dispersing aid (Pidisper 6240, manufactured by Pidilite Industries Limited, Mumbai) in a domestic wet grinder to get a fine slurry of ash. The slurry found to have a final solids content of 50%.

The following composition was prepared as described below ; Styrene-butadiene rubber latex 40% solids content 60parts

Fly ash slurry 50 % solids content 20 parts

Corn starch 90 % solids content 20 parts And water to make a final solid content of 40%

The corn starch is added to the Styrene-butadiene rubber latex (having 40% styrene and remaining butadiene) under stirring taking care that no lumps are formed . The fly ash slurry is then added. A needle punched polyester non woven fabric having a weight of 300gsm is dipped in the binder composition prepared as described above at room temperature. The excess pick up of the fabric is removed by passing through a squeeze rolls and the pick up is adjusted to get a final dry weight of 900g. It is then dried in hot oven at a temperature of 140 degree C for about 30 minutes and passed through a calendar roll to get a final thickness of 2.0mm. The resultant composite is found to have good flexibility, resilience, toughness and excellent stitch tear properties.

EXAMPLE 8 Preparation of a composite using coffee husk ash slurry:

The coffee husk ash is pulverized and sieved to get a powder having a particle size of 75 microns. lOOg of the resultant ash is mixed with 150g of water and 0.5g of dispersing aid (Pidisper 6240, manufactured by Pidilite Industries Limited, Mumbai, India ) in a domestic wet grinder to get a fine slurry of ash. The slurry found to have a final solids content of 40%. Binder composition:

The following composition was prepared as described below Styrene Acrylic copolymer latex 50% solids content 80parts ^•

Coffee husk ash slurry 40 % solids content 20 parts

To the Styrene Acrylic copolymer latex which has a styrene content of 70% and 30% butyl acrylate the coffee husk ash slurry is added at room temperature with stirring and mixed to get homogeneous mixture. A needle punched polyester non woven fabric having a weight of 200 gsm is dipped in the binder composition prepared as described above at room temperature . The excess pick up is removed by passing through a squeeze rolls and the pick up is adjusted to get a final dry weight of 600g. It is then dried in hot oven at a temperature of 150 degree C for about 20 minutes and passed through a calendar roll to get a final thickness of 1.4mm. The resultant composite is found to have good stiffness and satisfactory levels of tack developed upon dipping in a solvent like toluene. Advantages of the invention

• The composition employs ash which is a waste material in an useful manner thereby value adding to the otherwise a waste product.

• The composition of the present invention is easy and simple to prepare.

• The performance of the composite resulting from the process employing the composition of the present invention is comparable with the composite prepared by the present day available processes.

Claims

Claim

1 An improved impregnating or coating composition useful for variety of applications, which comprises polymer(s)/polymer emulsions/latex normally employed for such applications and ash from the vegetable origin such as husk and other ashes like fly ash, or a mixture thereof.

2. An improved composition as claimed in claiml, wherein the ash used in the composition is selected from rice husk ash, coffee husk ash, ground nut husk ash etc and other ash like fly ash etc .

3. An improved composition as claimed in claims 1 & 2, wherein the composition contains carbohydrate or their mixtures

4. An improved composition as claimed in claim 3, wherein the carbohydrate used is selected from corn starch tapioca starch, potato, pre-gelatinised starch or their mixtures or their modified versions.

5. An improved composition as claimed in claims 1 to 4, wherein the polymer employed in the composition is selected from natural and synthetic latexes, homo polymers and copolymers of acrylic, styrene, vinyl acetate, carboxylated monomers, ethylene, butadiene and its derivatives.

6. An improved composition as claimed in claims 1 to 5, wherein the amount of polymer used in the composition ranges from 50 to 90% by weight of the composition and the amount of ash or its mixtures ranges from 10 to 50 % by weight of the composition.

7. An improved composition as claimed in claims 3 to 6, wherein the amount of carbohydrate employed in the mixture ranges from 0.1 to 25% of the total weight of the composition.

8. An improved composition as claimed in claims 1 to 7, wherein the composition contains additionally other fillers, processing aids and other additives like plasticisers, surfactants, dispersing agents, anti settling agents, buffers, biocides and cross linking agents.

9 An improved composition as claimed in claim 8, wherein the other fillers used are selected from calcium carbonate, china clay, aluminum silicate, talc, etc are used.

10 An improved composition as claimed in claims 8 & 9, wherein the amount of other fillers, when present ranged from 2% to 40% preferably from 5% to

15% by weight of the total mass of the composition.

11 An improved composition as claimed in claims 8 to 10, wherein the amount of processing aids and other additives ranges from 0.1 to 10 % by weight, preferably from 3 to 7 % by weight of the total mass of the composition.

12 An improved process for the preparation of a composite useful for variety of applications which comprises: impregnating or coating a substrate with a composition as claimed in claims 1 to 11 and drying the treated substrate.

13 An improved process as claimed in claim 12, wherein the substrate used is selected from flat, flexible, fibrous and porous material.

14 An improved process as claimed in claim 12& 13, wherein the substrate used is a fibre mat comprising fibers selected from virgin fibers or with substantial amounts of secondary fibers in the form of wet laid fibre mat, non woven of type spun bonded, needle punched, stitch bonded etc.

15 An improved process as claimed in claims 12 to 14, wherein the drying is effected at temperature from 80 to 190 degree C, more preferably between 120 to 170 Deg. C. preferably betweenl 40 to 160 degree C.

16. An improved process as claimed in claims 12 to 15, wherein the ratio of the material to the composition is in the range of 1:0.1 to 1:6.0, preferably 1 :0.3 for insoles of wet laid fibre mat type and 1 :3 for fibre mats of non wet laid type for shoe stiffeners .

17 An improved process as claimed in claims 12 to 16, wherein the dried composite if desired is treated with an insolubliser , drying the materials again and cooling to room temperature.

18. An improved process as claimed in claim 17, wherein the insolubliser such as glyoxal is employed.

19 A composite useful for variety of applications like insoles and shoe stiffener applications prepared by the process as claimed in claims 12 to 18.

20. A composite of claim 19, wherein the composite is optionally coated with a hot melt adhesive on atleast one side.

21. A shoe incorporating the composite as claimed in claim 19.