POLYOLEFIN

TECHNICAL FILED OF THE INVNETION

This present invention relates to a method for preparing a blend composition of flour and polyolefin.

BACKGROUND ART

Bio-based polymers have gained more attentions in plastic industry because they can be obtained from natural ingredients and can be biologically decomposed. This causes reducing environmental problems resulted from those petrochemical-based polymers being difficult to be decomposed.

Starch is one of the bio-based polymers comprising polysaccharide of amylose and amylopectin as main components. When the starch is mixed with plasticizer at high temperature, starch transforms into a thermoplastic starch which similar to the thermoplastic polymer that is formable. However, thermoplastic starch has disadvantage in its mechanical properties. Therefore, it is blended with other polymers in order to improve its properties. Moreover, thermoplastic starch is hydrophilic because its structure contains many hydroxyl groups. Hence, when being mixed with other hydrophobic polymers (e.g. polyethylene, polypropylene, etc), they are not compatible. This makes obtained polymer blends from thermoplastic starch and other polymers have low strength. Many researches have focused on plasticizer and compatibilizer additives which are suitable for polymer blends from thermoplastic starch and other polymers in order to improve its mechanical properties including studies in blending method of thermoplastic starch and other polymers.

The making of polymer blends of thermoplastic starch and other polymers comprises mostly 2 main steps which are the preparation of thermoplastic starch and the blending of obtained thermoplastic starch with other polymers, which are complicated. Therefore, there are researches trying to combine these two steps into one such as JP2008296569 which disclosed equipment and preparation method for polymer composite of synthetic polymers and compositions obtained from biomass. This work focused on starch-based biomass. The preparation method was performed by subjecting high water content starch-based biomass to mixing and kneading equipment in order to give gelatinized starch and homogeneously mixed with synthetic polymers, following by dehydration step. However, equipment for the preparation of this polymer composite was 12 meters long in order to homogeneously mixed the synthetic polymers and starch.

US20120139154 disclosed the preparation method of blend composition of polymers and thermoplastic starch comprising the following steps: (1) adding dried starch into twin screw extruder in the first part of the extruder; (2) adding plasticizer into second part of the extruder in which starch from the first part would be mixed with plasticizer and gelatinized becoming to thermoplastic starch; and (3) adding dried polymers into the third part of the extruder next to the second part in order to mix thermoplastic starch and polymers in the extruder.

It can be seen from the inventions above, they all focused on the preparation of blend composition of thermoplastic starch and synthetic polymers by using starch as precursor. This is because starch has high purity and subjected to extractions of proteins, lipids, and other organic substances. This makes easier formation of thermostarch unlike flour which contains many impurities and difficult to be homogeneously mixed with synthetic polymers.

There was the study in subjecting flour from agricultural waste to blend with polymers such as Maderas. Cienciay tecnologia, 2015, 17, page 637-646 disclosed compositions and preparation method for blend composition of high density polyethylene, bagasse flour and nanoclay by using twin screw extruder for the study of influence of nanoclay to mechanical properties. It was found that said composition had good mechanical properties because both bagasse flour and nanoclay increased composition strength.

Journal of Applied Sciences and Engineering Research, 2013, 2, page 233-240 disclosed the composition and preparation method of blend composition of polyethylene and maize cob flour. It was found that maize cob flour had poor distribution in polyethylene which decreased the mechanical properties.

However, bagasse flour and maize cob flour as mentioned above were difficult to be formed into thermoplastic because main composition of bagasse flour and maize cob flour were cellulose. This was limited their utilizations of obtined polymer blend composition which needed high compatibility among blend compositions, for example film application.

From these reasons, this invention aims to develop the preparation method for blend composition of flour and polyolefin by simple method with maintaining the good mechanical properties and suitable to be formed by several processing methods. SUMMARY OF INVENTION

The present invention relates to a method for preparing a blend composition of flour and polyolefin using twin screw extruder, wherein said method comprising the following steps:

(a) adding flour containing protein, fiber, and lipid in the range of 5 to 25 % of dry weight into position 1 of said twin screw extruder;

(b) adding plasticizer into position 2 of said twin screw extruder;

(c) adding polyolefin into position 3 of said twin screw extruder;

wherein distance between position 1 and position 2 is in the range from 0 to 0.2 times of total length of extruder, and distance between position 2 and position 3 is in the range from 0.1 to 0.3 times of total length of extruder;

and wherein overall temperature of said twin screw extruder is in the range from 90 to 210 °C, and screw speed of said twin screw extruder is in the range from 200 to 500 rpm.

BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 shows the twin screw extruder used in the preparation of blend composition of flour and polyolefin according to the present invention.

Figure 2 shows viscosity of polypropylene, blend composition of flour and polypropylene of comparative sample A and sample according to the present invention (a) at 190 °C at different shear rate.

Figure 3 shows distribution of flour in blend composition of flour and polypropylene of comparative sample A and sample according to the present invention (a) - (f).

DESCRIPTION OF THE INVENTION

The present invention relates to the method for preparing a blend composition of flour and polyolefin which will be described according to the follows.

Any aspect being shown here aims to include every applications of other aspect of this invention unless stated otherwise.

Technical terms or scientific terms used herein, have definitions as understood by those person skilled in the art unless stated otherwise. Equipment, apparatus, methods, or chemicals mentioned herein means equipment, apparatus, methods, or chemicals commonly operated or used by person skilled in the art unless explicitly stated otherwise that they are equipment, apparatus, methods, or chemicals specifically used only in this invention.

The use of singular noun or plural nouns with term "comprising" in claims or in specification refers "one" and also "one or more", "at least one", and "one or more than one".

All compositions and/or methods disclosed and claimed in this application are aimed to include aspects of the invention from actions, operations, modifications, or changing without performing that significantly different from this invention, and obtaining similar objects with utilities and results of the present invention according to person ordinary skilled in the art although without stated in claims specifically. Therefore, substitution or similar objects to the present invention, including minor modifications or changing that clearly seen by person skilled in the art should be considered with scope in spirit, and concept of invention as appended claims.

Throughout this application, term "about" is used to indicate that any value presented herein that may potentially vary or deviate. Such variation or deviation may result from error of apparatus, method used in calculation or from individual operator implementing apparatus or methods.

"Phr" means ratio of additive or plasticizer to one hundred parts of blend composition of flour and polyolefin, wherein blend composition may include compatibilizer. Unless stated otherwise, phr is calculated by weight.

"Flour" means product obtained from field crop but not included agricultural waste or industrial waste that has been ground to powder. It may be used the simple method such as dry mill or grinding or wet mill or grinding without extraction or separation of any other compound, such as carbohydrate, protein, lipid, fiber, mineral, etc. from flour. This is different from starch that is extracted or separated other components.

"Thermoplastic flour" means including thermoplastic obtained from flour.

One objective of this invention is to develop the preparation method of composition of blended flour and polyolefin by using twin screw extruder.

Hereafter, invention embodiments are shown without any purpose to limit any scope of the invention. This invention relates to the method for preparing a composition of blended flour and polyolefm using twin screw extruder, wherein said method comprising the following steps:

(a) adding flour containing protein, fiber, and lipid in the range of 5 to 25 % of dry weight into position 1 of said twin screw extruder;

(b) adding plasticizer into position 2 of said twin screw extruder;

(c) adding polyolefm into position 3 of said twin screw extruder;

wherein distance between position 1 and position 2 is in the range from 0 to 0.2 times of total length of extruder, and distance between position 2 and position 3 is in the range from 0.1 to 0.3 times of total length of extruder;

and wherein overall temperature of said twin screw extruder is in the range from 90 to 210 °C, and screw speed of said twin screw extruder is in the range from 200 to 500 rpm.

Preferably, the distance between position 1 and position 2 is in the range from 0 to 0.1 times of total length of extruder.

Preferably, the distance between position 2 and position 3 is in the range from 0.2 to 0.3 times of total length of extruder.

In one aspect of the invention, flour in step (a) containing protein, fiber, and lipid in the range of 8 to 15 % of dry weight.

In one aspect of the invention, flour in step (a) has particle size in the range of 80 to 250 micrometers, preferably is in the range of 100 to 250 micrometers.

In one aspect of the invention, flour in step (a) is obtained from crops selected from genus Oryza, Triticeae, Zea, Metroxylon, or mixture thereof, preferably is obtained from crops selected from rice, cassava, corn, sago, or mixture thereof, wherein said flour may origin from South East Asian countries such as Thailand, Cambodia, Laos, Myanmar, Vietnam, Malaysia, Brunei, Indonesia, and Philippines.

In one aspect of the invention, position 1 in step (a) has temperature in the range from

90 to 100 °C.

In one aspect of the invention, plasticizer in step (b) may be selected from glycerol, sorbitol, or mixture thereof.

In one aspect of the invention, the ratio of plasticizer to flour is in the range from 3.5 : 10 to 7.5 : 10 by weight.

In one aspect of the invention, position 2 in step (b) has temperature in the range from 120 to 140 °C. In one aspect of the invention, polyolefin in step (c) may be selected from polyethylene, polypropylene, or mixture thereof.

In one aspect of the invention, polyolefin in step (c) may be further comprised of compatibilizer, preferably, compatibilizer is selected from polyethylene vinyl acetate, polypropylene-graft-maleic anhydride, or mixture thereof.

In one aspect of the invention, the ratio of flour to polyolefin is in the range from 1 : 2.5 to 1 : 8.5 by weight, preferably is in the range from 1 : 3.5 to 1 : 4.5 by weight.

In one aspect of the invention, position 3 in step (c) has temperature in the range from 160 to 210 °C.

In one aspect of the invention, screw speed of said twin screw extruder is in the range from 250 to 400 rpm.

In one aspect of the invention, between position 2 and position 3, kneading block may be further installed in order to give shear force from kneading screw and heat from barrel to flour and plasticizer to be gelatinized becoming thermoplastic flour with more efficiently.

In one aspect of the invention, between position 3 and the end of twin screw extruder, kneading block is further installed in order to give shear force from kneading screw and heat from barrel to thermoplastic flour and polyolefin to be mixed more efficiently.

In another aspect of the invention, this invention relates to the blend composition obtained from preparation method of a blend composition of flour and polyolefin according to this invention.

In another aspect of the invention, this invention relates to an article prepared from preparation method of a blend composition of flour and polyolefin according this present invention, wherein forming method of said article can be used in general thermoplastic forming method that may be selected from but not limited to extrusion, thermoforming, injection molding or casting.

The following examples are demonstrating of this present invention for the purpose only, not to limit scopeof this invention in any way.

Flour used in the method for preparing a blend composition of flour and polyolefin according to the present invention can be divided into 2 types which were dry milled flour and wet milled flour. Dry milled flour was prepared by subjecting rice into dirt separation and being milled. Wet milled four was prepared by subjecting rice into dirt separation and submerged in water before being milled, then the obtained wet milled flour was dried and subjected to mesh (size 120) to obtain flour with certain size. The dry milled flour and wet milled flour produced by said methods were analyzed

th for protein, lipid, moisture, and ash according to AO AC: Official method analysis, 15 ed. Association of Official Analytical Chemistry, Arlington, USA, 1990. Amylose was analyzed according to iodine affinity method using UV-Vis spectrophotometer and calculated from standard curve of amylose. The results are shown in Table 1.

The twin screw extruder used in the preparation of flour and polyolefin according to the invention is shown in Figure 1. The length per screw diameter (L/D) was about 40. Diameter (D) was about 26 mm.

Table 1 : Composition percentages and particle sizes of wet milled flour and dry milled flour

Comparative sample A

Comparative sample A was the blend composition of flour and polyolefin were prepared by the following 2 steps preparation method.

Step 1 : Preparation of thermoplastic flour

The wet milled flour, glycerol, and titanium dioxide were mixed in twin screw extruder as shown in Figure 1. The wet milled flour was added into position 1 passed the such screw and glycerol was added in position 2 in proportions as shown in Table 2. The barrel temperature of the twin screw extruder was in the range from 90 to 160 °C. The temperatures at position 1, 2, and 3 were about 90, 120, and 160 °C respectively. The screw speed was about 150 rpm. The obtained blend was extruded and cut into thermoplastic flour pellet.

Step 2: Preparation of blend composition of flour and polypropylene

Polypropylene, polyethylene vinyl acetate, and thermoplastic flour pellet were added at proportions as shown in Table 2 into position 1 of the twin screw extruder as shown in Figure 1. Barrel temperature of the twin screw extruder was in the range from 90 to 210 °C. The temperatures at position 1, 2, and 3 were about 90, 120, and 160 °C respectively. The screw speed was about 250 rpm.

Sample according to the present invention Sample (a) to (f) were prepared by twin screw extruder as shown in Figure 1 according to the invention that comprising the following steps;

The flour and titanium dioxide were added through feeding screw at position 1 at about 90 °C. Then, glycerol was added at position 2 about 10.4 cm apart from position 1 (distance LI) at about 120 °C. Then, polypropylene or blend of polypropylene and polyethylene vinyl acetate was added into position 3 about 31.2 cm apart from position 2 (distance L2). Polypropylene was melted and mixed with compositions in screw with barrel heated at temperature about 160 to 210 °C. Kneading block might be added between position 2 and 3 of the twin screw extruder in order to give shear force from kneading screw and heat from barrel to flour and glycerol to be gelatinized into thermoplastic flour. Moisture ventilation might be opened in order to reduce moisture in flour.

The blend of polypropylene and compositions was extruded from die and cut into thermoplastic flour pellet and subjected to properties testing.

Composition proportions of sample (a) to (f) are shown in Table 2. For the sample which added with polyethylene vinyl acetate, blend of polypropylene and polyethylene vinyl acetate, which was added at position 3, might be prepared by mixing of polypropylene and polyethylene vinyl acetate using tumbler mixer.

Sample (a) to (e) used screw speed for mixing about 250 rpm and the sample (f) used screw speed for mixing about 300 rpm.

Table 2: Proportions of blend composition of flour and polypropylene

Sample % by % by Glycerol % by weight % by weight Titanium weight weight (phr) of of dioxide of dry of wet polypropylene polyethylene (phr) milled milled vinyl acetate

flour flour

Comparative - 20 14.6 75 5 0.2 sample A

Sample (a) - 20 14.6 75 5 0.2

Sample (b) 20 - 8 80 - 0.2

Sample (c) 20 - 8 75 5 0.2

Sample (d) - 20 8 80 - 0.2

Sample (e) - 20 8 75 5 0.2 Sample (f) - 20 14.6 75 5 0.2

The following testing are property testing of blend composition of flour and polypropylene obtained from the present invention, wherein testing methods and equipments were generally used and not intended to limit the scope of the invention.

Rheological propertie was tested by capillary rheometer and melt flow index was tested by melt flow indexer (Model: MI4-Goettfert) according to ASTM D1238 standard at temperature about 190 °C under the weight about 2.16 kg.

Distribution property of flour in polyolefin was tested by scanning electron microscope.

Mechanical properties such as tensile strength, elongation at break and modulus were tested by universal testing instrument according to ASTM D638 standard. Impact strength was tested by Instrumented Pendulum Impact Tester according to ASTM D256 standard.

Table 3: Mechanical properties of blend composition of flour and polypropylene

Sample Modulus Tensile Strength Elongation at Impact strength break (%)

(MPa) (MPa) (J/m)

Comparative 1400 20.3 11 28.1

sample A

Sample (a) 1100 21.1 12 45.4

Sample (b) 1360 22.7 12 41.8

Sample (c) 1350 20.9 9.9 38.8

Sample (d) 1460 20.2 13 29.0

Sample (e) 1390 19.0 13 31.4

Sample (f) 1170 21.3 9.9 37.9

Comparison of rheological properties, distribution property, and mechanical properties of the blend composition of flour and polypropylene prepared from 2 steps of preparation method and method according to the present invention

Figure 2 shows rheological properties of comparative sample A and sample (a). It was found that both samples had similar rheological properties, wherein melt flow index of comparative sample A and sample (a) were about 5.04 and 6.19 g/10 min respectively. Figure 3 shows comparison between distribution property of flour of comparative sample A and sample according to the present invention (a) - (f), wherein comparative sample A was prepared from 2 steps preparation method and sample (a) - (f) were prepared from the method according to the present invention, it was found that the distribution of sample (a) was better.

From Table 3, when comparing mechanical properties of comparative sample A and sample (a), it was found that sample (a) which prepared from method according to the present invention provided higher impact strength.

Comparison of distribution property of flour and mechanical properties of the blend composition of flour and polypropylene prepared from dry milled flour and wet milled flour From Figure 3, when comparing distribution property of flour in the blend composition of sample (b) and (d) which prepared from dry milled flour and wet milled flour respectively, it was found that the preparation method of the blend composition according to the present invention influenced the distribution of dry milled flour and wet milled flour in the blend composition similarly. Moreover, when comparing sample (b) and (c) with sample (d) and (e), it was found that sample (c) and (e) which further containing polyethylene vinyl acetate provided better distribution than sample (b) and (d) which were not containing polyethylene vinyl acetate.

From Table 3 which shows mechanical properties of the blend composition according to the present invention, when comparing sample (b) and (d) with sample (c) and (e), it was found that sample (b) and (c) which prepared from dry milled flour provided higher tensile strength and impact strength than sample (d) and (e) which prepared from wet milled flour. It can imply that the different of particle size of flour and impurity in flour influenced to the mechanical properties of the blend composition of flour and polyolefin.

Comparison of mechanical properties of the blend composition of flour and polypropylene prepared by different screw speed

From Figure 3, when comparing the distribution of flour in the blend composition of sample (a) and (f) which prepared from method according to the present invention at screw speed at about 250 and 300 rpm respectively, it was found that the distribution of flour in polypropylene was not significantly different.

From Table 3, when comparing impact strength property of sample (a) and (f), it was found that the impact strength of sample (f) was slightly decreased. However, it was still higher than comparative sample A, whereas other mechanical properties of sample (a) and (f) were similar.

Comparison of mechanical properties of the blend composition of flour and polypropylene prepared from twin screw extruder at different mixing lengths

For the study of suitable mixing length of the twin screw extruder for the preparation of the blend composition of flour and polyolefin, the differences of distance between position 1 and 2 (length LI) and distance between position 2 and 3 (length L2) according to Table 4 were used in the preparation of the blends described previously, wherein compositions used in the preparation were similar to composition of sample (b). Results are shown in Table 4.

From Table 4, it was found that mechanical properties of the composition of blended flour and polyolefin had relationship with mixing length LI and L2. If said lengths were not suitable, it would lowered the mechanical properties of the blend composition, especially for the percentage elongation at break and impact strength.

Table 4: Mechanical properties of the blend composition of flour and polypropylene prepared by twin screw extruder at different mixing lengths

Length LI Length L2 Modulus Tensile strength elongation at impact (cm) (cm) break (%) strength

(MPa) (MPa) (J/m)

10.4 31.2 1360 22.7 12 41.8

20.8 31.2 1700 17.1 5.3 27.6

10.4 20.8 1450 21.3 9.9 38.4

BEST MODE OR PREFERRED EMBODIMENT OF THE INVENTION

Best mode or preferred embodiment of the invention is as provided in the description of the invention