Process for manufacturing a surface-treated compacted material processable on a single screw plastics conversion equipment

Abstract

The present invention relates to the field of processing thermoplastic polymers, particularly the present invention relates to a process for manufacturing compacted material suitable for the use in thermoplastic polymers without a compounding step, comprising the steps of a) providing at least one primary powder material; b) providing at least one molten surface treatment polymer; c) simultaneously or subsequently feeding the at least one primary powder material and the at least one molten surface treatment polymer into the high speed mixer unit of a cylindrical treatment chamber; d) mixing the at least one primary powder material and the at least one molten surface treatment polymer in the high speed mixer, e) transferring the mixed material obtained from step d) to a cooling unit, as well as the compacted material obtained by this process and its use in thermoplastic polymers.

Claims

1. A surface-treated compacted material in the form of non-uniform and loosely compacted conglomerates of singularized coated particles having a mean particle size of 10 m to 100 mm, wherein the surface-treated compacted material is obtained by a process comprising the following steps: a) providing at least one primary inorganic powder material at a temperature of between 20 C. and 300 C., wherein the at least one primary inorganic powder material is calcium carbonate that is optionally treated with a fatty acid; b) providing at least one molten surface treatment polymer selected from the group consisting of an ethylene copolymer, an ethylene-1-octene copolymer, a metallocene based polypropylene, a polypropylene homopolymer, and an amorphous polypropylene homopolymer; c) simultaneously or subsequently feeding the at least one primary inorganic powder material from step a) and the at least one molten surface treatment polymer from step b), and optionally at least one surface treatment agent, into a single screw high speed mixer; d) mixing the at least one primary inorganic powder material and the at least one molten surface treatment polymer in the single screw high speed mixer at 400 to 4000 rpm so that the surface treatment polymer forms layers around and totally coats singularized particles of the primary inorganic powder material; e) optionally transferring the coated particles of the primary inorganic powder material obtained in step d) to a second single screw high speed mixer and mixing the same; and f) cooling the coated particles of the primary inorganic powder material obtained from step d) or e) to directly obtain a surface-treated compacted material in the form of non-uniform and loosely compacted conglomerates of the singularized coated particles, wherein the non-uniform conglomerates have a mean particle size of 10 m to 100 mm, and wherein the surface-treated compacted material (i) comprises 5 to 25 wt % of the surface treatment polymer and 75 to 95 wt % of the at least one primary inorganic powder, (ii) has a screen residue of more than 80 wt. % on a 45 m screen, and (iii) is free flowing according to DIN-53492.

2. The surface-treated compacted material according to claim 1, that is completely redispersible in thermoplastic polymer matrices without a compounding step.

3. The surface-treated compacted material according to claim 1, that is non-dusting.

4. The surface-treated compacted material according to claim 1, wherein at least one surface treatment agent is fed simultaneously with or after the feeding of the at least one primary inorganic powder material into the single screw high speed mixer.

5. The surface-treated compacted material according to claim 4, wherein the temperature of the surface treatment agent is between 20 C. and 300 C.

6. The surface-treated compacted material according to claim 4, wherein the temperature of the surface treatment agent is between 60 C. and 250 C.

7. The surface-treated compacted material according to claim 4, wherein the temperature of the surface treatment agent is between 60 C. and 120 C.

8. The surface-treated compacted material according to claim 4, wherein the surface treatment agent is stearic acid, zinc oxide, a synthetic paraffin wax, a polyethylene metallocene wax or a polypropylene wax.

9. The surface-treated compacted material according to claim 4, which comprises 9.5 wt % of the surface treatment polymer, 0.5 wt % of the surface treatment agent, and 90 wt % of the at least one primary inorganic powder.

10. The surface-treated compacted material according to claim 4, wherein the at least one surface treatment agent is present in the surface-treated compacted material at 0.5 to 5 wt %.

11. The surface-treated compacted material according to claim 1, wherein step e) takes place.

12. The surface-treated compacted material according to claim 1, wherein the at least one molten surface treatment polymer is added to and mixed with the surface-treated material of step d) in a second single screw high speed mixer.

13. The surface-treated compacted material according to claim 1, wherein the temperature of the primary inorganic powder material is between 60 C. and 250 C.

14. The surface-treated compacted material according to claim 1, wherein the inorganic powder is natural ground calcium carbonate (GCC), precipitated calcium carbonate (PCC), or a mixture of GCC and PCC.

15. The surface-treated compacted material according to claim 1, wherein the inorganic powder is ground calcium carbonate (GCC) selected from marble, chalk, calcite, limestone, or any mixture thereof.

16. The surface-treated compacted material according to claim 1, wherein the inorganic powder is precipitated calcium carbonate (PCC) selected from aragonitic PCC, vateritic PCC, calcitic PCC, rhombohedral PCC, scalenohedral PCC, or any mixture thereof.

17. The surface-treated compacted material according to claim 1, wherein the surface-treated compacted material is further processed in a single-screw plastics conversion equipment.

18. The surface-treated compacted material according to claim 1, wherein the at least primary inorganic powder material is calcium carbonate and is present in the surface-treated compacted material at 86 to 92 wt %.

19. The surface-treated compacted material according to claim 1, wherein the surface-treated compacted material has a screen residue of more than 90 wt. % on a 45 m screen.

Description

DESCRIPTION OF THE FIGURES

(1) FIG. 1 is a microscopic picture of the initial powder of Example 1

(2) FIG. 2 is a microscopic picture of the compacted material of Example 1.

EXAMPLES

Example 1

(3) This example relates to the preparation of a surface-treated non-dusting compacted material according to the present invention.

(4) A horizontal Ring-Layer-Mixer/Pelletizer, namely Amixon RMG 30 with process length of 1200 mm, and diameter of 230 mm, equipped with 3 feeding ports in sequence, and 1 out-let port, was used. The cylinder is fitted with a heating/cooling double wall. Surface treatment and compacting is obtained by a rotating, cylindrical, pin-fitted screw.

(5) Component A (Primary Powder Material):

(6) Natural calcium carbonate (GCC)) with a mean particle size of 2.7 m, treated with 0.5 wt-% stearic acid, is preheated to 110 C., and fed gravimetrically into the first feed port at the rate of 22.6 kg/hr.

(7) Component B: (Surface Treatment Polymer)

(8) Component B is injected in liquid state at a temperature of 230 C. through feeding port 2 at the required rate (kg/hr.) related to component A to be surface treated, in this example at 2.4 kg/hr.

(9) Component B Consists of a Blend of: 80 wt-% ethylene-1-octene-copolymer (e.g. Affinity GA 1900/Dow), Density (ASTM D792) 0.87 g/cm.sup.3 20 wt-% metallocene based polypropylene wax (e.g. Licocene PP-1302/Clariant), Density (23 C.; ISO 1183)) 0.87 g/cm.sup.3.

(10) Mixing

(11) Surface treatment and compacting is carried out in the Ring-Layer-Mixer/Pelletizer at 180 C. and a screw speed of 800 rpm.

(12) The surface treated product leaves the Mixer/Pelletizer through the outlet port, is transferred by gravity into a second Ring-Layer-Mixer/Pelletizer for compacting and cooling, operated at a temperature of 140 C. and a screw speed of 400 rpm. In this example, both units are of identical size and dimensions. The resulting surface treated and compacted material leaves the unit through the outlet port, and is free of dust and free flowing.

(13) Application:

(14) The surface treated/compacted material has a concentration of 90.5 wt-% of calcium carbonate (GCC). The quality of the surface treatment is evaluated by the degree of re-dispersion when extruding a blend of compacted material and virgin polymer.

(15) Precisely, in this example, for the blown film production, a LLDPE (Dowlex NG 5056G/Dow) was used, adding 17 wt-% of the compacted material and 83 wt-% weight of said LLDPE.

(16) The equipment used therefor was a conventional Dr. Collin single screw extruder, Type E-25P, equipped with blown film die of 60 mm diameter and 1.2 mm thickness. Temperature profile for the extruder was at 220 C., screw speed at 70 rpm.

(17) Both products, LLDPE resin and the compacted material were fed by gravimetric dosing. The resulting film had a thickness of 40 m.

(18) For comparison, a standard type, LLDPE-based calcium carbonate master batch, containing 70 wt-% of calcium carbonate (Omyalene 2011A/Omya), is processed under identical conditions and the same final concentration of calcium carbonate in the film.

(19) The resulting films for both products, the compacted material and Omyalene 2011A are visually controlled under a binocular magnifier with magnification of 50 and found free of any undispersed agglomerates. For further evaluation, both blown film samples containing 17 wt-% of the compacted material, and 22 wt-% of master batch (Omyalene 2011A), respectively, were tested for Dart-drop test (ASTM D 1709) and Elemendorf-tear resistance test (ISO 6383-2).

(20) The film made with the compacted material had a dart drop of 620 g and a tear resistance of 710 cN and 810 cN in machine and cross direction.

(21) The film containing masterbatch had a dart drop value of 630 g and a tear resistance of 670 cN and 880 cN in machine and cross direction.

(22) These results confirm the complete and uniform dispersion of the calcium carbonate(GCC) of the compacted material when processed on a standard single screw extruder.

(23) Free flow properties of the compacted material are evaluated by DIN-53492 standard.

(24) Results are: untreated natural calcium carbonate powder: 10 mm opening: no flow compacted material as per example 1: 10 mm opening: 7 sec/150 g

(25) Particle Size

(26) Evaluation according to ISO 3310.

(27) TABLE-US-00001 Result: 92 wt-% <500 microns 56 wt-% <250 microns 35 wt-% <160 microns 4 wt-% <45 microns

(28) These results confirm that the compacted material of example 1 is free of dust and free flowing.

(29) The effect of the process is also clearly shown looking at FIG. 1, being a microscopic picture of the initial powder and FIG. 2 being a microscopic picture of the compacted material of example 1.

Example 2

(30) For surface treatment and cooling, the same equipment and processing parameters were used as in example 1.

(31) Component A (Primary Powder Material):

(32) Natural talc powder with a mean particle size of 10 m (Finntalc M30SL/Mondo Minerals) is gravimetrically fed into feed port 1 at a rate of 20 kg/hr.

(33) Component B (Surface Treatment Polymer):

(34) Component B is injected in liquid state at a temperature of 230 C. into feed port 2 at a rate of 5 kg/hr.

(35) Component B consists of a blend of: 90 wt-% metallocene based PP (e.g. Metocene HM 1425/Lyondel-Basell). 10 wt-% Zn-stearate (e.g. Zincum 5/Baerlocher).

(36) The resulting, surface treated and compacted material contains 80 wt-% of talc, is free of dust and free flowing.

(37) Application:

(38) The degree of dispersability is evaluated by extruding a blend of 20 wt-% of the compacted material and 80 wt-% of virgin polymer. The extrusion is carried out on a conventional Dr. Collin single screw extruder type E25P, fitted with a flat die (220 mm opening) at a temperature profile of 190 C. and a screw speed of 80 rpm. The resulting stripe is then pressed on a hot press to a sheet of 0.2 mm thickness.

(39) For this example, a polypropylene homopolymer type TM-6100K/Montell and a HDPE type Hostalene GC-7200/Clariant were used as the virgin polymers.

(40) By visual examination of the pressed sheets under a binocular magnifier with magnification of 50, no agglomerates or undispersed particles could be detected, and the dispersion is judged as excellent in both polymers.

(41) Free flow properties of the compacted materials are evaluated by DIN-53492 standard.

(42) Results are: untreated natural talc powder: 10 mm opening: no flow compacted material as per example 2: 10 mm opening: 18 sec/150 g

Example 3

(43) For the powder treatment a high speed batch mixer from MTI-Mischtechnik Industrieanlagen GmbH Type LM 1.5/2.5/5 with a 2.51 vessel and with a three part standard mixing tool was used. The mixer was heated to 175 C. 364 g of a calcium carbonate like in example 1 were filled in the vessel. The vessel was closed and the mixer was run for 2 minutes at 700 rpm. Then the mixer was opened and 32 g of polypropylene homopolymer with a solid density of 0.86 g/ml and a melting point (DSC) of 152 C. plus 4 g zinc oxide type Brlocher Zincum 5 were added to the preheated powder. The mixer was closed again and run for 12 minutes at 700 rpm.

(44) To test the dispersion of the obtained treated powder a Dr. Collin lab extruder FTE20TIS with a standard screw and with a standard tape die was used. All heating zones were heated to 175 C. and the extruder was run at 100 rpm. 80 wt-% HDPE Type LyondellBasell Hostalen GC 7260 and 20 wt-% of the obtained powder were continuously fed in the extruder by a gravimetric dosage system. 10 g of extruded tape were then compression moulded between two chromed steel plates at 190 C. The obtained film was optically inspected under a binocular magnifier with magnification of 50 and showed no visible agglomerates.

Example 4

(45) The compacted material of example 1, containing 90.5 wt-% of natural calcium carbonate and 9.5 wt-% of surface treatment polymer was evaluated for sheet extrusion applications in polystyrene.

(46) General purpose polystyrene from BASF type 158K (GPPS) and high impact polystyrene from BASF type 486M (HIPS) were used. 56 wt-% of each polystyrene were added to 44 wt-% of said compacted material.

(47) Both components were continuously gravimetrically dosed to the feed hopper of the processing extruder. In the case of GPPS the total feed rate was 15.6 kg/h and in the case of HIPS it was 14.7 kg/h. A conventional Collin single screw extruder type E25P with a Collin flat film extrusion die and a Collin polishing stack were used to produce a 250 mm wide and 1 mm thick sheet. The temperature profile of the extruder was 180 C., 195 C., 230 C., 230 C. and 230 C. The extrusion die was kept at 230 C. and the calendaring rolls at 100 C. The die gap was 1.2 mm and the nip width of the calendaring rolls was 1.0 mm. The line sped was set to 0.8 m/min. The screw was underfed at a speed of 160 rpm. With this set up sheets without visible agglomerates under a binocular magnifier with magnification of 50 could be produced.

(48) 10 g of each extruded sheet were then compression moulded between two chromed steel plates at 190 C. The obtained film was optically inspected under a binocular magnifier with magnification of 50 and showed no visible agglomerates.