BACKGROUND OF THE INVENTION;
It is known to use polypropylene epoxies, vinyl esters etc. for making
natural fiber reinforced composites. However, composites made from
petroleum based resins are not degradable and pose a threat to the
environment as they are not easily recyclable. Further, they increase the
dependence on petroleum products. Therefore, there is a growing
demand for an alternative to the existing petroleum based resins.
Various agricultural products have been used in the preparation of
resins. US Patent No. 6,306,997 discloses soybean based adhesive resins
and composite products made using such resins. The resin is made from
soybean flour, crosslinking agent and plant-material. US patent
6,806,353 also discloses biodegradable plant protein compositions and
method for the preparation thereof. The water resistant resin uses soya
protein, polylactide, crosslinking agent, compatibilizer and plasticizer. US
2006/0264135A1 to Netravali et al. discloses cured soy protein with
green strengthening additive an fabrication of such into green
composites.

US 2008/0090939A1 to Netravali et al teaches biodegradable soya
protein based compositions using soya protein, natural strenghing agent
and composites formed therefrom.
However, the need exists in the industry to provide composites which are
stronger, can be made at reasonable costs, and avoid the use of synthetic
materials.
OBJETS OF THE INVENTION:
It is therefore an object of this invention to provide natural resins and
the composites produced therewith, which are stronger than available
composites.
It is a further object of this invention to provide natural resins and the
composites produced therewith, which can be made at reasonable costs.
Another object of this invention is to provide natural resins and the
composites produced therewith, which is totally biodegradable.
Yet another object of this invention is to provide natural resins and the
composites produced therewith, which avoids the use of synthetic
materials.

These and other objects and advantages of the invention will be apparent
from the ensuing description.
DESCRIPTION OF THE INVENTION:
According to this invention is provided a natural resin and the use
thereof for the production of jute fiber reinforced composites.
In accordance with this invention, a mixture of soya milk along with
cashew nut shell liquid, organically modified/unmodified nanoclay and a
cross linking agent has been used as an eco friendly resin to develop
rigid natural fiber composites. Soaked soya seeds are crushed and the
milk is squeezed using a nylon filter cloth. Obtained soya milk is made
alkaline using ammonium hydroxide and the pH maintained slightly
above 9 to arrest bacterial attack of soya milk. To this cashew nut shell
liquid (CNSL) l%-20% (by w/v%) is added and stirred well.
Unmodified/organically modified nanoclay is added and stirred under
ultrasonication for about 30 min for homogeneous dispersion of nanoclay
in the aqueous resin mixture. Other additives and cross linking agent,
each in 1-15% (by w/v) is added to this emulsion and stirring continued.
The viscosity of the emulsion increases and this is the pre cured resin.
Natural fiber woven/non woven fabrics are dipped in this pre cured resin
for resin incorporation and dried till the resin incorporated natural fiber

fabrics contain a prescribed amount of moisture content between 15-
40%. The dried natural fabrics are stacked one above the other and
pressed in a hydraulic press with pressure 8-14 ton, 110-150°C for 8-30
min. Obtained laminates are tested for mechanical, physical and
chemical properties.
Soya milk is used in 10 to 30 parts per 100 parts of the fabric, by weight.
The fabrics is used in the process are woven as non-woven fabrics, made
from natural fabrics, e.g. jute felt etc. The cross-linking agents used are
selected from hexamine, hexamethylene tetramine, glyoxal,
glutaraldehyde and the additive used is boric acid. The cross linking
agent and additive each make-up 1 to 15% weight by volume of the
composition. The clay added is selected from organically modified and
unmodified inorganic nanoclay such as MMT, Cloisite 20A etc. The clay
is used in a proportion of 1 to 15% by weight.
Solvents may also be employed such as polyvinyl alcohol, polyethylene,
glycol, glycerol etc. Additionally, guar gum, gelatin etc may be used to
enhance the strength of the composite.
The invention will now be explained in greater detail with the help of the
following non-linking example.

Example
Soaked soya seeds were crushed and the milk was squeezed using a
nylon filter cloth. The soya milk was made alkaline using ammonium
hydroxide and the pH was maintained slightly above 9.
To this was added the cashew nut shell liquid and stirred well. The
modified/unmodified nanoclay was then added and stirred under
ultrasonication for 30 minutes for homogeneous dispersion of the
nanoclay in the mixture. The additives and cross-linking agents were
then added to the emulsion and stirring was continued. The natural
fibre fabrics were dipped into this resin mixture and dried till the fabrics
attained a moisture Content of 15 to 40%. The dried fabrics were stacked
one above the other and pressed in a hydraulic press at 8 to 14 ton at a
temperature of 120°C for about 20 minutes. The general procedure was
followed for each of the examples under the control composite (composite
1) and the composites 2 to 20 according to the invention:
Names of the additives and cross-linking agents, and the individual
proportion of each for the production of biodegradable natural resin
based jute fiber reinforced composites.

The water absorption WA and Equilibrium moisture content (EMC) of
jute and jute based composites at ambient condition has been tested and
the results are given in Table -1, the mechanical properties of jute fiber
and its composites are shown in Table-2, comparative properties of
composites containing natural fiber and/or different commercial and
soya based resins are shown in Table-3, the tensile properties of
commercially available natural fiber composites are shown in Table-4
and the results of thermal degradation of composites by
thermogravimetric analysis (TGA) are shown in Table-5.

Table 1. Water absorption (WA) and Equilibrium moisture content (EMC)
of jute and jute based composites at ambient condition

*Ref: Natural fiber reinforced polymer composites in automotive
applications, J. Holbery and D. Houston, JOM, Nov 2006
Table 5. Results . of thermal Degradation of Composites by


Biodegradation study
Biodegradation study was done through soil burial test (BIS 1623-1992).
Garden soil, sand and manure were mixed in the ratio 2:1:1. Moisture
content of the mixture was adjusted to 22-30%. This mixture was spread
uniformly in a jar and the sample was placed over the soil mixture in a
jar. About 5-6 cm of soil mixture was spread over the sample and the jar
covered with a petridish which was incubated at 30°C and the moisture
content maintained manually between 22-30%. After specified days
samples were removed, cleaned thoroughly using distilled water and
dried at 60°C over night. Samples were weighed and mechanical
properties tested.
Table 6. Weight loss after soil burial biodegradation study in ambient


Table 7: Properties of composites after biodegradation study in soil burial
condition

The prepared composite is biodegradable, cost effective, eco friendly in
comparison with the existing biodegradable natural fiber composites. The
current invention involves usage of soya milk instead of SPI or SPC
thereby bringing a ten-fold decrease in cost. Soya milk differs from SPC
and SPI in the amount of protein and carbohydrate content.
Carbohydrate present provides better adhesion of the resin to the fiber
surface and cross linked proteins provide strength to the resin matrix.
CNSL added acts as a preservative and also gives better adhesion of the
resin to the fiber surface. The current invention exhibits favorable tensile
strength, which can be used in automotive industry, instrument
cabinets, furniture and for together applications. Soya milk is used as a
cost effective fully biodegradable resin.
WE CLAIM:
1. A process for the production of fibre reinforced composites
comprising the steps of obtaining soya with by crushing soaked
soya seeds, and maintaining the soya milk at pH above 9, adding
thereto
optionally 1 to 20% by weight of cashew nut shell liquid and stirring well, followed by the addition of nanoclay and homogeneously dispersing the same, to obtain an emulsion, adding a cross-linking agent and additives to the emulsion with stirring dipping fabrics into the emulsion, followed by drying to obtain dried fabrics having a moisture content of 15 to 40%, stacking the fabrics one over the other, followed by pressing to obtain the composites.
2. The process as claimed in Claim 1, wherein soya milk is used in a proportion of 10 to 30 parts by weight of the fabrics.
3. The process as claimed in Claim 1, wherein the clay is an organically modified nanoclay as unmodified inorganic nanoclay.
4. The process as claimed in Claim 1, wherein the nanoclay is added in a proportion of 1 to 15% by weight of the fabrics.

5. The process as claimed in Claim 1, wherein the additive is boric acid.
6. The process as, claimed in Claim 1, wherein the additive is present in 1 to 15% by weight.
7. The process as claimed in Claim 1, wherein the cross-linking agent is selected from hexamine, hexamethylene tetramine, glyoxal and glutaraldehy de.
8. The process as claimed in Claim 1, wherein the cross-linking agent is present in 1 to 15% by weight.
9. The process as claimed in Claim 1, wherein the stacked fabrics are pressed under a pressure of 8 to 14 ton and at a temperature in the range of 110 to 150°C for 8 to 30 minutes.
10. A composition for use in the production of natural fibre reinforced composites, comprising:
10 to 30% by weight of soya milk;
1 to 15% by weight of nanoclay;
1 to 15% by weight of a cross-linking agent;
1 to 15% by weight of an additive;

optionally 1 to 20% by weight of cashew nut shell liquid.
11. The composition as claimed in Claim 10, wherein nanoclay is selected from unmodified inorganic clay and organically modified clay.
12. The composition as claimed in Claim 10, wherein the additive is boric acid.
13. The composition as claimed in Claim 10, wherein the cross-linking agent is selected from compounds such as hexamine, hexamethylene tetramine, glyoxal and glutaraldehyde.
14. The composition as claimed in Claim 10, optionally including solvents selected from glycerol, polyethylene glycol, polyvinyl alcohol.