DESC:
TECHNICAL FIELD
The invention relates to a field of polypropylene composite, particularly to the polypropylene composite including a fragrant powder, and process of preparation thereof.

BACKGROUND AND PRIOR ART
Polymer composites having fragrant ingredients such that the composites have good fragrance are desired.

KR101490625B1 (SAMSUNG TOTAL PETROCHEMICALS Co., Ltd.) discloses a polypropylene resin composition having improved fragrance. More specifically, the present invention can provide an environmentally friendly polypropylene resin composition which has excellent fragrance characteristics and physical properties by including a polypropylene resin, polypropylene waste plastic, and brewed coffee powder.

KR101578324B1 (KOREA LOGIS POOL CO., LTD.) discloses a light weight plastic product containing the coffee waste. Provided is a manufacturing method of a lightweight plastic product, which comprises the steps of: melting coffee grounds and a resin including polyethylene (PE) or polypropylene (PP); and moulding the molten composition. The moisture contents of the coffee grounds is less than or equal to 0.3% before melting.

IN201641015805 (Dr N. Jayachitra) discloses preparation of composites of renewable spent coffee powder with polypropylene matrix employing extrusion processing technique. In this invention a method of preparation of spent coffee powder reinforced composites comprising 10 to 50 % of reinforcement, 50 to 100% matrix polypropylene granules and 1-5% of coupling agent is described.

OBJECTS OF THE INVENTION
One of the objects of the present invention is to provide a polymer composite comprising fragrant materials such that the composite has perceptible fragrance.

Another object of the present invention to provide a polymer composite comprising fragrant materials such that the composite has uniform colour.

Yet another object of the present invention is to provide a polymer composite comprising fragrant materials that provides acceptable gelling when the composite granules are moulded.

SUMMARY OF THE INVENTION
According to one aspect of the present invention, there is provided a polypropylene composite comprising:
a. 85-95% by weight polypropylene homopolymer, and;
b. 6-15% by weight a fragrant powder, wherein the particle size of the fragrant powder is in the range of 50-400 microns.
According to another aspect of the present invention, there is provided a process of preparation of a polypropylene composite comprising the steps of:
a. Adding 85-95% by weight polypropylene homopolymer and 6-15% by weight a fragrant powder to a twin screw extruder and extruding at a temperature in the range of 150-300 degrees Celsius, and;
b. Cooling the extrudate and;
c. Chopping the extrudate to obtain chips of polypropylene composite.

BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
Figure 1 shows a twin screw extruder used in process of preparation of polypropylene composite

DETAILED DESCRIPTION OF THE INVENTION
According to one aspect of the present invention, there is provided a polypropylene composite comprising:
a. 85-95% by weight polypropylene homopolymer, and;
b. 6-15% by weight a fragrant powder, wherein the particle size of the fragrant powder is in the range of 50-400 microns.
According to another aspect of the present invention, there is provided a process of preparation of a polypropylene composite comprising the steps of:
a. Adding 85-95% by weight polypropylene homopolymer and 6-15% by weight a fragrant powder to a twin screw extruder and extruding at a temperature in the range of 150-300 degrees Celsius, wherein the particle size of the fragrant powder is in the range of 50-400 microns and;
b. Cooling the extrudate, and;
c. Chopping the extrudate to obtain chips of polypropylene composite.

Composition of the polypropylene composite
Polypropylene homopolymer
The polypropylene composite comprises of 85-95% by weight polypropylene homopolymer, preferably 85 - 94% by weight. The polypropylene homopolymer is preferably 88-92% by weight of the polypropylene composite, more preferably 89-91% by weight of the polypropylene composite.

Melt flow index of the polypropylene homopolymer is preferably in the range of 10-12.

Density of polypropylene homopolymer is preferable in the range of 0.8-1.0 g/cc, more preferably in the range of 0.85-0.98 g/cc and most preferably in the range of 0.88-0.96 g/cc.

Melting point of polypropylene homopolymer is preferably in the range 150-180 degrees Celsius, more preferably in the range 155-175 degrees Celsius and most preferably in the range 160-170 degrees Celsius.

Fragrant powder
The polypropylene composite comprises of 6-15% by weight fragrant powder. The fragrant powder is preferably 8-12% by weight of the polyprropylene composite, more preferably 9-11% by weight of the polypropylene composite.

The fragrant powder is selected from coffee powder, tea powder, cocoa powder, or spice powder. The fragrant powder preferably has an aroma that is easily and distinctively perceived by humans.

Coffee powder can be instant coffee powder or ground coffee powder, preferably ground coffee powder.

Tea powder can be green tea powder or black tea powder, preferably green tea powder. Tea powder may be instant tea powder or leaf tea powder, preferably leaf tea powder.

Spice powder is preferably selected from powder of one or more of the following: pepper, clove, cinnamon, cardamom, nutmeg, turmeric, dried ginger, fennel, and allspice.

Moisture content in the fragrant powder is preferably less than 1% by weight, more preferably less than 0.7% by weight and most preferably less than 0.5% by weight.

Antioxidant
The polypropylene composite preferably comprises an antioxidant. Antioxidant is preferably phenolic type or phosphide base. Antioxidant, when present is preferably 100-5000 ppm of the polypropylene composite, more preferably 200-4000 ppm of the polymer composite and most preferably 300-2500 ppm of the polypropylene composite

Colour pigments
The polypropylene composite preferably comprises one or more colour pigments. The colour pigments of various shades and palates are well known in the art, and can be used. It is also known to use a mixture of colour pigments in order to obtain a desired colour shade.Carbon black may be used preferably as a colour pigment. The pigment of various colours may be combined, including but not limited to: yellow, orange, red, brown, blue, violet, green and black. The colour pigments are preferably 50-5000 ppm of the polypropylene composite

Processing aids
The polypropylene composite preferably comprises processing aids, including lubricants. The processing aids are 500-2500 ppm of the polypropylene composite.

Processing of the polypropylene composite
The process of preparation of a polypropylene composite comprising the steps of:
a. Adding 85-95% by weight polypropylene hompolymer and 6-15% by weight a fragrant powder to a twin screw extruder and extruding at a temperature in the range of 150-300 degrees Celsius, wherein the particle size of the fragrant powder is in the range of 50-400 microns and;
b. Cooling the extrudate, and;
c. Chopping the extrudate to obtain chips of polypropylene composite.

According to a preferred aspect, the process of preparation of a polypropylene composite comprising the steps of:

a.
(i) Adding 85-95% by weight polypropylene homopolymer to the main hopper of a twin screw extruder, and;
(ii) Adding 6-15% by weight fragrant powder to the sideways hopper of the screw extruder, wherein the sideways hopper is located downstream of the main hopper and the distance between the main hopper and the sideways hopper is in the range 0.8-1.6 m, wherein the particle size of the fragrant powder is in the range of 50-400 microns, and
(iii) extruding at a temperature in the range of 150-300 degrees Celsius, and
b. Cooling the extrudate, and;
c. Chopping the extrudate to obtain the chips of polypropylene composite.

Any ingredients of the composition of the polypropylene composite including but not limited to antioxidant, colour pigments, and processing aids, are added to the twin screw extruder. Such ingredients are preferably added to the main hopper along with the polypropylene homopolymer. Fragrant powder is preferably added to the sideways hopper.

The distance between the main hopper and the sideways hopper is preferably in the range 0-1.6 m, more preferably in the range of 0.8-1.2 m, and most preferably in the range 0.9-1.1 m.

The step (a) of the extrusion is carried out preferably in the temperature range of 150-300 degree Celsius, more preferably in the temperature range of 160-250 degrees Celsius and most preferably in the temperature range of 170-210 degree Celsius.

The RPM of twin extruder is preferably in the range of 500-1000, more preferably in the range of 550-900, and most preferably in the range of 600-800.

DRAWINGS
FIGURE 1 PROCESS OF PREPARATION OF A POLYPROPYLENE COMPOSITE
The Figure 1 shows a twin screw extruder (1) having a barrel (2) with counterrotating twin screws (3a,3b), a main hopper (4) and a sideways hopper (5) located downstream of the main hopper (4) at a distance of (6) from the sideways hopper (5).

The twin screw extruder includes a band heater (7) for heating the contents of the barrel and a cooling coil (8) surrounding the barrel (2) for cooling the contents of the barrel by passing a coolant, e.g. cold water through the coil.

Polypropylene homopolymer, and any additives (except fragrant powder), if present, are added to the main hopper (4) and the fragrant powder is added to the sideways hopper (5). The temperature of the contents is controlled to be in the range of 150-210 degrees Celsius by controlling the rate of heating using the band heater (7), the flow rate of the coolant in the cooling coil (8) and rpm of the twin screws (3a,3b).

Polypropylene homopolymer is molten and mixed thoroughly with the fragrant powder by means of rotation of the twin screws (3a, 3b), and the molten mix liquid extrudes out of the the die (9) of the twin screw extruder (1).

The melt extrudate is passed through a cooling chamber (10) comprising cold water, and the cooling causes the extrudate to solidify. The solidified extrudate is then passed through a cutter (11) where it is subjected to cutting to create granules or chips of polypropylene composite.

The granules of the polypropylene composite may then be packed in a moisture-resistant or anti-moisture packaging in order to avoid contact of the granules with moisture.

The granules of polypropylene may be further subjected to a step of injection moulding to create articles of desired shape using the polypropylene composites. For this the granules may be melted and fed into an injection moulding machine via hopper dryer into the mould, and used to create an article of desired shape.

EXAMPLES
The invention will now be demonstrated with the help of examples. The examples are for the purpose of illustration only and do not limit the scope of the invention in any manner.

Process of preparation of composites
Polypropylene homopolymer
Polypropylene homopolymer used was from APPL, India (APPL Grade Appcom 1110). The melt flow index of the homopolymer was in the range of 10-12, unless specified otherwise. The polypropylene homopolymer was added to the twin screw extruder through the main hopper. The amount of polypropylene homopolymer used varied from example to example and is specified in the tables (in the range of 5-95% by weight of the polypropylene composite)

Fragrant powder
Commercially available ground coffee powder was purchased from Ozone Agrochemicals, Bangalore, Karnataka (India) and was used in all the experiments. The coffee powder had moisture content of less than 0.5% by weight.

The coffee powder was used at various amounts ranging from 6-15% by weight of the polypropylene composite as specified in the tables. The experiments were carried out using 10% by weight of coffee powder, unless specified otherwise.

The particle size of the coffee powder used was that passing through mesh 200 (particle size less than 74 microns), except where specified otherwise.

The coffee powder was fed into the twin screw extruder via the sideways hopper located downstream of the main hopper, unless specified otherwise. In all the examples, the distance between the main hopper and the sideways hopper was 1 m, unless specified otherwise.

Processing
Experiments were carried out using Berstorff make twin screw extruder. The temperature in the extruder was maintained at 160-210 degrees Celsius. The twin screws were counterrotating at rpm of 600-800.

The polypropylene homopolymer and coffee powder were fed, and the melt was extruded from a die (diameter of 3 mm) into cold water (water temperature of 25 degree Celsius). The solidified extrudate was cut using a wire cutter to create polypropylene composite granules of cylindrical shape of length in the range of 2-5 mm.

The granules were then moulded into a standard swatch using injection moulding, the dimensions of the swatches are: 9 cm length, 7 cm breadth, and 2.5 mm thickness.

Evaluation of the swatches
The swatches prepared were evaluated for colour, fragrance and gelling.

Fragrance of the swatches was evaluated by a subjective scoring given by a panel of 5 experts, on a scale of 1-10 with higher scores being more preferred.

The colour was evaluated visually, by comparing the colour of the swatch against the colour of the coffee powder. The colour was rated as too light, light, medium, dark, or too dark. The colour that matches closest to the colour of ground coffee is termed as medium, and is the most preferred. The colour of swatch, when different from the ground coffee powder is termed as light, too light, dark or too dark.

The gelling was evaluated visually.

TABLE 1: EFFECT OF % BY WEIGHT OF COFFEE POWDER IN THE POLYPROPYLENE COMPOSITES
The amount of coffee powder as % by weight of the polypropylene composite was varied from 5-15 % by weight, as tabulated below with polypropylene homopolymer accounting for the rest of the weight of the composite. Melt flow index of polypropylene homopolymer was 10-12. The swatches of the composites were made according the procedure described above and evaluated for fragrance and colour. All the experiments were carried out using coffee powder passing through 200 mesh (particle size less than 74 microns)

EX NO Coffee Powder (% by weight of the composite) Colour
Fragrance Score of the Swatch

1 5 Too light 4
2 8 Light 6
3 10 Medium 8
4 12 Dark 9
5 15 Very Dark 10

From the results, it is clear that swatches corresponding to Examples 2-5, which are within the scope of the invention provide acceptable fragrance and colour as compared to the fragrance and colour of swatch of Example 1 that is out side the scope of the invention

TABLE 2: EFFECT OF PARTICLE SIZE OF THE COFFEE POWDER
All the examples below were prepared with coffee powder being 10% by weight of the polypropylene composite, with the rest of the weight being polypropylene homopolymer of melt flow index of 10-12.

EX NO Mesh size Coffee powder
particle size
(microns) Colour Fragrance Score
6 200 Less than 74 Medium, Uniform, most preferred 8
7 200 – 80 74 – 177 Medium, Less Uniform, preferred 8
8 80 – 40 177 – 400 Medium, Colour Patches, Acceptable 8

From the results, it is clear that all the examples 6-8, which are within the scope of the invention have acceptable fragrance and colour score. Increasing particle size of the coffee powder reduces the uniformity of colour, although the overall colour scores remain acceptable.

TABLE 3: EFFECT OF MELT FLOW INDEX OF POLYPROPYLENE HOMOPOLYMER

Composites of Examples 9-11 were prepared using 10% by weight coffee powder, with the particle size of the coffee powder less than 74 microns (passing 200 mesh), by varying melt flow index of the homopolymer, as tabulated below.

EX NO Melt flow index (MFI) Colour Fragrance Score Gelling quality
9 10 -12 Medium 8 Good, most Preferred
10 5-9 Medium 8 Burning observed, preferred
11 More than 10 -12 Medium 8 Gelling poor, acceptable

It can be seen that all the examples 9-11 which are within the scope of the invention provide acceptable fragrance and colour. In terms of gelling quality, all the examples have acceptable gelling quality, with the examples with MFI in the range 5-12 being preferred and with the example 9 with MFI of 10-12 being most preferred.

TABLE 4: EFFECT OF THE LOCATION OF COFFEEPOWDER FEEDER
Composites for Examples 12-14 were prepared using 10% coffee powder, with the particle size of the coffee powder less than 74 microns (passing 200 mesh), and melt flow index of the homopolymer of 10. The results are tabulated below

EX NO Coffee powder feeding Fragrance Mixing Colour
12 Main hopper 6, burnt odour detected Uniform Too dark
13 Sideways hopper (distance 1 m from main hopper) 10
Uniform Medium
14 Sideways hopper (distance 1.2 m from main hopper) Not evaluated Inconsistent, Non-uniform light and dark patches

All the Examples 12-14 are within the scope of the invention. It is clear that feeding the coffee powder in a sideways offer provides some benefit in terms of fragrance and colour.
,CLAIMS:
1. A polypropylene composite comprising
a. 85-95% by weight polypropylene homopolymer, and;
b. 6-15% by weight a fragrant powder, wherein the particle size of the fragrant powder is in the range of 50-400 microns.

2. A polypropylene composite as claimed in claim 1 wherein melt flow index of polypropylene is in the range 6-15.

3. A polypropylene composite as claimed in claim 1 or 2 wherein the fragrant powder is selected from coffee powder, tea powder, cocoa powder, or spice powder.

4. A polypropylene composite as claimed in any one of the preceding claims wherein the moisture content in the fragrant powder is less than 1% by weight.

5. A polypropylene composite as claimed in any one of the preceding claims wherein the composite comprises 100-5000 ppm antioxidant.

6. A polypropylene composite as claimed in any one of the preceding claims wherein the composite comprises 500-2500 ppm processing aid.

7. A process of preparation of a polypropylene composite comprising the steps of:
a. Adding 85-95% by weight polypropylene hompolymer and 6-15% by weight a fragrant powder to a twin screw extruder and extruding at a temperature in the range of 150-300 degrees Celsius, , wherein the particle size of the fragrant powder is in the range of 50-400 microns., and;
b. Cooling the extrudate, and;
c. Chopping the extrudate to obtain chips of polypropylene composite.

8. A process as claimed in claim 7 comprising the steps of
a. (i) Adding 85-95% by weight polypropylene homopolymer to the main hopper of a twin screw extruder, and;
(ii) Adding 6-15% by weight fragrant powder to the sideways hopper of the screw extruder, wherein the sideways hopper is located downstream of the main hopper and the distance between the main hopper and the sideways hopper is in the range 0.8-1.6 m, and
(iii) extruding at a temperature in the range of 150-300 degrees Celsius, and
b. Cooling the extrudate, and;
c. Chopping the extrudate to obtain the chips of polypropylene composite.