Title of Invention

A PROCESS FOR THE PREPARATION A QUICK SETTING POLYMER COMPOSITION

Abstract

This invention relates to a process for the preparation of a quick setting polymer composition comprising the steps of adding a diisocyanate compound such as herein described to a solution of a first diof compound such as herein described, the ratio of the diisocyanate composition to dio being in the range of 4.2 to 1.1. followed by adding a catalyst solution thereto, such as herein described in the proportion of 0.067 % to 0.2% of the total mass of the reactants to obtain a prepolymer mixture, adding a solution of a second diol to the prepolymer mixture such that the two diols are in a wt % of 10-90 wt% and 90-10 wt% and allowing the reaction to continue for a predetermined period, such as herein described followed by partial evaporation of the solvent to obtain the quick setting polymer composition.

Full Text

- 1A -FIELD OF THE INVENTION This invention relates to a process for the preparation of a quick setting polymer composition. This invent ion further relates to a quick setting polymer composition, for forming sheets or impregnating fabric, for applications in high strength composites. BACKGROUND OF THE . INVENTION In high strength composites, curing time and temperature play a key role. Some applications may require cutting/setting of the item by moisture at ambient temperature at a faster rate simultaneously having adequate working/shaping,time. Such appli cations also, require good shelf stability in af moisture free sealed packing.. So. for composite applications, a fabric: with suitable weave pattern requires to be impregnated with the polymer in a moisture-free condition and,packed immediately under inert atmosphere. The polyurethanes undergo hardening by moisture curing in presence of a suitable catalyst- such ,a material comprises a fabric coated/impregnated with about 40-250% by weight of resin based on the uncoted fabric having a reasonable shelf life in moisture-free condition. OBJECTS OF THE INVENTION It is therefore an object- of this invention to propose a process for the preparation of a quick setting polymer composition which is strong and has quick setting properties. -3- 10-20 mins. with constant stirring. At the end, a high viscous polyurethane solution is obtained. Some amount of THF is removed under reduced pressure. In an embodiment according to this invention, the composition is cast on a substrate such as a glass or a fabric followed by moisture curing to obtain the polyurethane sheet or polyurethane impregnated fabric. Moisture curing of the sheet or the coated fabric is allowed by exposing the sheet on glass plate or the coated fabric to ambient environment upto 24 hrs.. Such sheet or the coated fabric developed adequate strength and dimensional stabi1ity even after 20 mins. exposure to ambient atmospheric humidity. The diols are selected from ethane dial, butane diol, neopentyl glycol (NPG), diethsnolamine and polyethylene glycol(PEG). The two diols are used in the range of 10-9o wt% and 90-10 wt%. One of the following diisocyanates, viz . TD1 (2,4-toluenediisocyanate), MDI (4,4'-diphenylmethane diisocyanate), HDI (hexa-methylene di isocysnate), IPDI range of 4.2 to 1.1- An organometal1ic compoundsuch as dibutyltindilaurate is used as a catalyst alongwith an organic solvent. The fabric used for impregnating the polymer couiposition is selected from gless fabric , carbon fibre , polypropylene fabric and jute fabric. 3 - 4 - The invention will now be explained in greater detail with the help of the f ol lowing non-limiting examples. EXAMPLE 1 The process remains same as described herein. The ratio of the dials : TD1 and catalyst is as follows : NPG: PEG) : TDI = 3 :1 : 6 on mole basis and catalyst (dibutyl 4 00 tin dilaurate) used varies from 0,067% to 0.2% of the total mass of the reactant. This polymer shows a setting time of 27 mins. to 12 mins- (judged by non-sticking to finger touch) depending on the amount of catalyst used and for a dry film thickness of 8µ. The carbon fiber composite prepared from this resin gives a tensile strength value of 375 Mps, which is quite a high value for many known applications of composite materials. EXAMPLE 2 The sequence of addition of the diols and TDI remains same. The catalyst is N~benzylmorpholine. The catalyst is used in 0.2% of the total mass of the reactants. The polymerisation time is 4 hrs.. At the end of the polymerisation, reaction solvent is completely removed from the reaction vessel to get a viscous mass- This resin having this particular catalyst shows a very good storage stability. This resin in presence of moisture sets to a hard mass in 40 mins.. This resin prepared in this way is highly stable in aqueous medium and in dilute alkali medium. Thermogravimetric analysis of the resin shows stability upto o 200 C. RESULTS Density The density of the pure polyurethane sheet was found to be 1.19 gm/cc at 29 °C. IR and XRD IR study of a polyurethane film sample (Fig. 1 of the accompanying drawing) showed no peak for free NCO group at 2274 cm-1 for residual -NCO group. XRD study showed amorphous nature of the polymer. Thermal study Thermogravimetric analysis (10 °C/min heating rate) of the pofyurethane sample in air showed that the polymer is thermally stable upto 250 °C. Tensile strength Tensile strength of the pure polyurethane sheet varied from 27 to 36 Mpa and elongation at break ranged from 360-140% depending on the NCO/OH ration. The carbon fiber composite prepared from this polyurethane showed a tensile strength of 250 Mpa for a particular composition. Chemical durability No weight loss of polyurethane sheet in 10% aqueous sodium hydroxide solution takes place upto 7 days. In cone. H2 SO4 dissolution of the polymer occurs with 3 hrs, while in cone. HNO3 dissolution takes place in 30 mins. Water absorption The prepared polyurethane showed no water absorption upto 34 days at room temperature (30°C). 5 The composition of the prepared polyurethane is new. One of the components in the composition controls, the tailorabilifty of the strength/flexbibility. Polyester polyurethane is hydrolytically less stable. So its properties are affected by moisture. Since polyurethane of the invention is non-polyester based, it is not degraded by contact with moisture or water. -7 - We Claim 1. A process for the preparation of a quick setting polymer composition comprising the steps of adding a diisocyanate compound such as herein described to a solution of a first diol compound such as herein described, the ratio of the diisocyanate composition to diol being in the range of 4.2 to I.I followed by adding a catalyst solution thereto such as herein described in the proportion of 0.067 % to 0.2 % of the total mass of the reactants to obtain a prepolymer mixture, adding a solution of a second diol to the prepojymer mixture such that the two diols are in a wt % of 10-90 wt % and 90-10 wt % and allowing the reaction to continue for a predetermined period such as herein described followed by partial evaporation of the solvent to obtain the quick setting polymer composition. 2. The process as claimed in claim 1, wherein said diisocyanate compound is selected from TDI (2,4-toluenediisocyanate), MDI (4,4'-diphenylmethane diisocyanate), HDI (hexamethylene diisocyanate), IPDr(l-isocyanato-3-isocyanatomethyl -3, 5, 5-trimethyl- cyciohexane), singly or in combination. 3. The process as claimed in claim 1, wherein the said first and second diol is selected from ethane diol, butane diol, neopentyl glycol, diethanolamine and polyethylene glycol. 4. The process as claimed in claim 1, wherein said catalyst is an organometallic compound such as dibutyl tin diiaurate or an amine such as N-benzylmorpholine. 5. The process as claimed in claim 1, wherein said solvent is such as THF. 6. The process as claimed in claim 1, wherein the reaction is carried out at a temperature in the range of 5 to 55" C. - 8 - 7 The process as claimed in claim I, wherein the reaction mixture is stirred for 1-2 mins. before addition of the catalyst solution. 8. The process as claimed in claim 1, wherein the prepolymer mixture is allowed to, continue for 15-45 mins. before addition of the second diol 9. The process as claimed in claim 1, wherein the reaction is allowed to continue for 10-20 mins. after addition of the second diol. 10. The process as claimed in claim 1, wherein said polymer composition is optionally cast on a substrate. 11. The process as claimed in claim 10, wherein said substrate is glass or a fabric such as glass fabric, carbon fibre, poly-propylene fabric or jute fabric. 12. The process for the preparation of a quick setting polymer composition substantially as herein described. This invention relates to a process for the preparation of a quick setting polymer composition comprising the steps of adding a diisocyanate compound such as herein described to a solution of a first diof compound such as herein described, the ratio of the diisocyanate composition to dio being in the range of 4.2 to 1.1. followed by adding a catalyst solution thereto, such as herein described in the proportion of 0.067 % to 0.2% of the total mass of the reactants to obtain a prepolymer mixture, adding a solution of a second diol to the prepolymer mixture such that the two diols are in a wt % of 10-90 wt% and 90-10 wt% and allowing the reaction to continue for a predetermined period, such as herein described followed by partial evaporation of the solvent to obtain the quick setting polymer composition.

Documents:

00686-cal-2000 abstract.pdf

00686-cal-2000 claims.pdf

00686-cal-2000 correspondence.pdf

00686-cal-2000 description(complete).pdf

00686-cal-2000 description(provisional).pdf

00686-cal-2000 form-1.pdf

00686-cal-2000 form-18.pdf

00686-cal-2000 form-2.pdf

00686-cal-2000 form-3.pdf

00686-cal-2000 form-5.pdf

00686-cal-2000 g.p.a.pdf

00686-cal-2000 letters patent.pdf

686-CAL-2000-FORM 27.pdf