Title of Invention


Abstract A polymeric solid foam float is manufactured by plastic injection moulding method by mixing of CBAs, nucleating agent and lubricating agent to the polyamide polymer granules and moulding is done on machine with nozzle having shut-off valve. The mould is having plurality of runners and gates. A vent in a form of gap is configured between upper plate and lower plate encompassing runners and gates for venting the gases evolved during the moulding processes from the moulding cavity.
Full Text FORM 2
The Patents Rules, 2003
"A process for making solid polymeric foam floats'

(a) NAME : DEO, Makarand Vasant
(b) NATIONALITY: An Indian National.
(c) ADDRESS : Akshay, Survey No. 43, Plot-67,
Navsahyadri Hou. Society,
Karve nagar, Pune-411 052, M.S., India

The following specification describes the invention.

The following specification particularly describes the invention and the manner in which it is to be performed.

Technical field of Invention:
The present invention is related to a process for making solid polymeric foam floats which can be used for level indications. More particularly, the present invention is related to a process for manufacturing solid foam floats using engineered thermoplastic.
Background and Prior art:
Since many years a typical low level warning indicator consists of a float that is required to float above the liquid level of the media of which low level in a reservoir (in which the liquid is stored) need to be automatically sensed to understand the 'warning' that the liquid level has been reduced or exhausted to its low or the liquid level has dropped to almost empty. When the reservoirs are of 'life saving device' such as brake of an automobile or fuel of generator set, it is extremely essential that the low or empty level warning indication is mandatory. The float density or sp. gravity or volumetric weight is a key factor for its 'FLOATING' above the liquid level.
Conventionally the same was achieved by joining the 2 bowls (UPPER and LOWER) by way of either welding or heat sealing or ultrasonically welding of the two bowls or by blow moulding a balloon type floats so that as the central portion being hollow the density reduction is possible and the float can float on the media level in which it is working.
Objects of present invention:
The main object of present invention is to produce solid foam float of shape that suits desired application which is completely homogenous and impermeable float with effective density reduction to suit its floating

Another object of the present invention is to produce a cost effective, durable, long lasting solid polymeric foam float.
Yet another object of the present invention is to use proposed floats for level indication as well for any other purpose where low density of the float is required.
Detailed description of the invention:
The rigid solid foam float of desired shape and size is manufactured by foam moulding process.
The solid foam float is manufactured using engineered thermoplastic such as Nylon-6 (PA-6) or Nylon-66 that is compatible in the mineral, non-mineral, vegetable based fluids (such as brake fluid) acids and alkalies and a vast range of chemicals. The Nylon-6 foam is formed using suitable blowing agent by which the foaming process is done in the mould cavity. In some cases the float may have to be used on electronic level switch that consists of a housing with reed switch or a reed relay that actuates with the help of a magnetic field around the reed switch hence the float need to have a magnet of suitable power (GAUSS and FLUX). This magnet which is to be inserted is moulded along with the float moulding.
The polymer that is compatible with fluid media is selected and the moulding of it's foam with control of the desired dimensional specs and standard without voids is a very critical process; wherein it is required to control and reduce the initial density below 0.7 gm/cc. considering the application; we have selected to use base polymer - Nylon-6 of which the initial density is 1.14 gm/cc is foamed using blowing agents to achieve the required density reduction. The blowing agents are of 2 types, particularly physical blowing agents (PBAs) and chemical blowing agents (CBAs)

As moulding of foam using PBAs needs a tedious machine set up the foam moulding is best done using CBAs. The PBAs are gases and mostly used are the Nitrogen and carbon dioxide or a mixture of both. The chemical blowing agents are the chemicals those evolve gases in plasticized state of the polymer (or liquid phase) by decomposition either by exothermic or endothermic process on either a conventional plastic injection moulding machine or on SPM (SPECIAL PURPOSE MACHINE). The mould used for foam moulding differs a lot in concept when compared to a normal plastic injection moulding is considered. The mould need to have a different style of runner and gate design and also need to have innovative venting considering the foam moulding otherwise the product may develop voids instead of smooth close cell formation with a thin skin and may fail in the endurance TESTS or in normal working as the voids may get filled by the fluid in which the float functions. To have a smooth cell formation it is of importance to choose a right CBA or foaming agent of which decomposing temperature is lower than the polymer melting point. The foam process generates air bubbles in the polymer melt and this bubble generation needs a liquid and solid interface wherein the bubbles are said to form by a nucleation process and the solid particles within the polymer melts are called as nucleating agents. The solid particles of nucleating agents serve as the sites for formation of bubbles thus the suitable nucleating agent need to be added to the polymer before it is subjected to the foaming process as it is very difficult to produce desirable foam without nucleating agent. At the same time the melt flow rate i.e. the viscosity of the plasticized polymer also plays a major role in 'FLOW of the polymer melt into the mould cavity; without formation of void or a blow hole in the moulded part. Thus it is very essential to add an external lubricating agent to the polymer powder or granules before its foam processing that provides for or acts as catalyst to

ease the flow of polymer melt inside the mould cavity without generation of voids.
In this way, to produce solid foam float along with a suitable CBA for the polymer chosen, it is of absolute essence to add nucleating agent and lubricating agent suitable for the moulding process and the mould need to have innovative runner and gate designs along with an innovative venting of the mould to release the excess unwanted gas out of the polymer melt and to have a smooth micro cell formation without voids. As the viscosity of the polymer melt drops considerably the polymer melt is found drooling out of the nozzle of the conventional plastic injection moulding machine that just works on 'SUCKBACK' pressure. To manufacture the solid foam float it is necessary to use a shut-off valve nozzle to effectively control the polymer drooling and to maintain a proper volumetric weight of the float.
For foam moulding it is also essential to break the injection pressure applied on the polymer melt as this needs to have a fixed volume of polymer melt to go inside the mould cavity through its runner and gate provided in the mould with a comparably low pressure to control the volumetric weight and ensure complete filling of the cavity without possible under fills. The innovative gate and runner design also helps to break the applied injection pressure; that is depending on the size and shape of the float.
Thus a polymeric solid foam float is manufactured by plastic injection moulding method by proper addition of CBAs, nucleating agent and lubricating agent to the polymer granules and moulding is done on machine with nozzle having shut-off valve and the mould that is designed in an innovative manner with innovative venting, runner and gate system. The other moulding parameters such as temperature pressure and hold

time are dependent on case to case basis Put following can be the guideline for using polyamide as the base polytfier.

1) Temperature:
Zone 1 Zone 2 Zone 3 Zone 4
2) Injection Pressure
3) Mould locking pressure
4) Hold time

185°C - 205°C 210°C-230°C 235°C - 250°C 250°C - 270°C
350 - 550 kg/cm2 #00-1000kgs/cm2 0-18 seconds.

Advantages of present invention:
1) The float is a solid foam float and it works strongly in rigorous working conditions and endurance tests. Thus it suits on life saving devices like Brake system of passenger cars/automotive application.
2) Complete robust design that is impermeable to the fluid media in which it works.
3) Provides a wide range of working temperatures ranging from - 40 degree centigrade to +140 degrees centigrade in which hollow floats fail to work.

Dated this 31st march 2009,






873-MUM-2009-CLAIMS(MARKED COPY)-(13-5-2013).pdf










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Patent Number 258588
Indian Patent Application Number 873/MUM/2009
PG Journal Number 04/2014
Publication Date 24-Jan-2014
Grant Date 23-Jan-2014
Date of Filing 01-Apr-2009
# Inventor's Name Inventor's Address
PCT International Classification Number A01K75/00
PCT International Application Number N/A
PCT International Filing date
PCT Conventions:
# PCT Application Number Date of Convention Priority Country
1 NA