Method and device for producing a thermoplastic granulate material

Abstract

In the production of thermoplastic granulate material, after mixing the starting materials, it is common in the state of the art for these materials to be kneaded and compressed in extruders, with subsequent granulation. According to the invention, no extruder is used, rather the starting materials for the thermoplastic granulate material are supplied directly to a double belt press after the mixing. Subsequently, the generated web-type to sheet-type body is processed into a granulate material by means of grinding, or is used as a web-type, sheet-type, strip-type or film-type intermediate product for the production of a further intermediate product or end products.

Claims

1. A method of producing a thermoplastic granulate material from several starting materials, comprising at least two materials selected form the group consisting of plastic powder, plastic granulate, additives, plasticizers, color materials, color pigments, lubricants, fillers, additives, and mixtures thereof, said method comprising the following steps: selecting starting materials and dosing said starting materials in a preselected mixing ratio; feeding said starting materials into at least one mixer; mixing said starting materials within at least one mixer while heating or and cooling a mixture produced therein yield a pourable intermediate substrate material dispersing said intermediate substrate material onto a press; treating said intermediate substrate material within said press thermally and mechanically to yield a thermoplastic web-shaped dimensionally stable body; and comminuting said thermoplastic web-shaped dimensionally stable body to yield a thermoplastic granulate material; wherein a plurality of different intermediate substrate materials are produced within said at least one mixer and differ at least with respect to one characteristic selected from the group consisting of color, mechanical characteristics, and chemical characteristics; wherein at least two different intermediate substrate materials are dispersed onto said press; and wherein said at least two different intermediate substrate materials are dispersed at least in two layers.

2. The method of claim 1, wherein said step of dispersing comprises dispersing said intermediate substrate material onto a lower belt of a double-belt press.

3. The method of claim 1, wherein said heating is performed within a first mixer and said cooling is performed in a second mixer.

4. The method of claim 1, wherein said heating and cooling is performed in a combined heating/cooling mixer.

5. The method of claim 1, wherein said different intermediate substrate materials are produced sequentially within a heating and a cooling mixer.

6. The method of claim 1, wherein said different intermediate substrate materials are produced in parallel within several heating and cooling mixers.

7. The method of claim 1, wherein a layer sequence of said different intermediate substrate materials dispersed onto said press is disturbed mechanically at least partially at least in vertical or horizontal direction before passing through a heating zone of said press.

8. The method of claim 7, wherein said step of mechanically disturbing said layer sequence comprises at least one action selected from the group consisting of vibrating, brushing, spiking, plowing, kneading.

9. The method of claim 1, wherein said intermediate substrate material dispersed onto said press in one or more layers is subjected to shear forces during passing through a heating zone of said press.

10. The method of claim 7, wherein said intermediate substrate material dispersed onto said press in one or more layers is subjected to shear forces during passing through a heating zone of said press.

11. The method of claim 1, wherein at least a first pourable intermediate substrate material is dispersed onto said press in one or more layers, is processed within said press and is subsequently comminuted to yield a first thermoplastic granulate material, and wherein a second pourable intermediate substrate material is dispersed onto said press in one or more layers, is processed within said press and is subsequently comminuted to yield a second thermoplastic granulate material differing from said first thermoplastic granulate material at least with respect to one characteristic selected from the group consisting of color, mechanical characteristics, and chemical characteristics, and being stored separately from said first thermoplastic granulate material.

12. The method of claim 1, wherein said step of comminuting is performed within a comminutor selected from the group consisting of a belt granulator, a punch, a mill and a chopper.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Further details, features and advantages of the invention will be pointed out in the subsequent description and, in addition, in connection with the embodiments of the inventions described in the description and schematically represented. In the drawings show:

(2) FIG. 1 a schematic representation of the process for manufacturing a thermoplastic granulate material according to the invention, as well as a new installation for the method;

(3) FIG. 2 a further variant of the new method according to FIG. 1 as well as the installation for performing the method;

(4) FIG. 3 a detail from FIG. 2;

(5) FIG. 4; a detail from FIG. 1;

(6) FIG. 5 a detail from FIG. 2; and

(7) FIG. 6 a detail from FIG. 5.

(8) Initially it should be mentioned that terms such as left, right, top or bottom only relate to the representation within the drawings, but in the actual embodiment it may deviate in practice. In addition it should be mentioned that the drawings do not represent technical drawings, this being the reason why hatchings and fault lines partially are not present. Also the relative dimensions may deviate in practice. Reference numerals that are not mentioned in the description can be taken from the reference list. The references have the same meanings in all figures.

(9) The schematic representation in FIG. 1 shows that the starting materials 9 for the manufacture of a thermoplastic granulate material 11, 12 or 13 are housed in individual containers 1a . . . 1n. These starting materials 9 may for instance be different plastic powders 9a and 9b, different additives 9c and 9d, different plasticizers 9e and 9f, different color materials 9g and 9h, different lubricants 9i and 9j, different fillers 9k and 9l and/or different additives 9m and 9n. A starting material frequently used in practice for a plastic powder is PVC (polyvinylchloride), as well as other polymers.

(10) Via a tubing system 10for instance by means of integrated spiral conveyors initially the starting materials selected from the starting materials 9a . . . 9n for a first type/species of thermoplastic granulate material, the first plastic powder 9a, the first additives 9c, the second plasticizer 9f, the first color material 9g, the first filler 9k and the second additive 9n are fed into a first mixer 2. Already at this point according to a first embodiment of the mixing the starting materials selected according to a first embodiment may be mixed in the ratio, such as necessary for the desired thermoplastic first granulate material 11.

(11) But also according to a second embodiment of the mixing within the manufacturing process in the first mixer 2 there may be present only parts of the final composition.

(12) The mixing within the first mixer 2 may be performed batch-wisei.e. discontinuallyor in a suitable first mixer 2 continually. The revolutions of the stirring blades of the first mixer 2 are selected so that the mixture of starting materials is heated to a desired temperature. From the first mixer 2, the heating mixer, the mixed starting materials are fed to a second mixer 3, the so-called cooling mixer.

(13) At this point in practice the parts of the formulation that are still absent are added, e.g. a further filler, e.g. for assisting the cooling.

(14) With respect to the first and the second mixers 2, 3 it should be noted that together they form a first heating/cooling mixer 15.

(15) The mentioned course of action, i.e. the method step of filling the first mixer 2 until to the outputting of a pourable thermoplastic intermediate substrate 6, the powdery mixture out of the second mixer 3 has been adapted as a standard, since for instance the particles of the thermoplastic polymer are opened by the plasticizer in the best way. If this method step would be performed in one step, then inter alia the absorption of plasticizers or extenders into the particles of the thermoplastic polymer would be too much impeded.

(16) During mixing of the starting materials in the second mixer 3a friction or shearing heat is generatedalso at very low feeding pressurewhich is dissipatedif it exceeds a preset limit.

(17) For instance only half of the intended amount of the fillers 9k and/or 9l is fed into the first mixer 2, and the second half of the intended amount of the fillers 9k and/or 9l is then fed into the second mixer 3. The second half of the amount of fillers is virtually a coolant at the same time.

(18) The pourability of the thermoplastic intermediate substrate 6 produced in the heating/cooling mixer 15 within the scope of the invention is so important, since the latter substrate 6 after the heating/cooling mixer 15 shall be dispersed homogeneously onto the lower belt 18 of a double-belt press 4 by means of a known caster (not shown in the drawings).

(19) The thermoplastic intermediate substrate 6, the mixed starting materials 9 which are provided onto the lower belt 18 of a double-belt press 4, lead to a particular type of granulate materiala first granulate material 11which only later is mixed with granulate materials 12 and/or 13 of other types for producing in total a dotted or speckled or structured designed appearance of a thermoplastic web 19 to be made thereof.

(20) The term one species within the scope of this invention however does not only mean only a particular color of a granulate material, but also a particular gloss or decorative effect. In addition also further physical characteristics, such as conductivity, flammability, density, particular shape, particulate distribution, etc. may determine a species or type.

(21) The intermediate substrate dispersed onto the lower belt 18 of the double-belt press 4, in FIG. 1 here being the powdery mixture 6, in the further course of action within the double-belt press 4 within the gap formed between the two belts running around in the conveying direction depicted with an arrow, are treated thermally and mechanically, whereby an intermediate product, a dimensionally stable body 17, is generated which leaves the end of the double-belt press 4. This dimensionally stable body 17, see FIG. 4, finally in a further method step is processed to a thermoplastic granulate material 11. To this end a comminutor 5 is provided which in the embodiment shown in FIG. 1 preferably directly follows onto the double-belt press 4.

(22) By selecting a suitable type of comminutor, e.g. one or more impact mills or one or more belt granulators or similar devices, the particulate size and the particulate distribution of the thermoplastic granulate material 11 to be produced can be determined arbitrarily and flexibly.

(23) Also this feature is a decisive advantage when compared with the production method according to the prior art, wherein the extrusion method is used, since during the extrusion broad particulate size distributions or a fast and frequent change of the particulate size together with time-consuming configuration changes of the extruder and subsequent mixing steps of the generated granulate materials would result.

(24) Thus, by the method according to the invention a homogeneous type of a granulate material, e.g. of one color together with an arbitrarily selectable particulate size distribution results which then may be fed to a granulate storage 20.

(25) If later on a thermoplastic web 19 of a particular appearance shall be produced, then the necessary components 23 and the necessary intermediate products, are retrieved from the intermediate storage, here the granulate storage 20, possibly are mixed in desired ratios and are then fed to a double-belt press for producing the final product; in the embodiment according to FIG. 1 this is the second double-belt press 7.

(26) The shape of the particle is determined by the press gap and by the selection and setting of the one or more comminutor(s).

(27) It can be easily seen that by using the process according to the invention a particularly high increase in flexibility is obtained with respect to the thermoplastic granulate material and with respect to the final product.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

(28) A further embodiment of the method according to the invention is the production of multi-colored granulate materials. To this end, e.g. from several heating/cooling mixers 15 and 16 which produce pourable intermediate substrates 6, 21 of different colors in parallel, several layers of intermediate substrates 6, 21 are dispersed onto the lower belt 18 of the double-belt press (Thermofix installation) in alternating sequence by color or side by side, see FIGS. 2 and 3, and thereafter during running through the double-belt press 4 a planar formation having multiple layers or multiple colors in vertical and/or horizontal direction is generated as intermediate product, namely the dimensionally stable body 22, see also FIG. 5. Thereafter with the comminuting step 5, mentioned already above, preferably thereafter, there is produced the granulate material of multiple colors itself and having clearly distinct color surfaces.

(29) According to a further embodiment of the method according to the invention also the thermoplastics granulate material may be produced not with clearly determined color boundaries, namely e.g. with blurred color boundaries, such as shown exemplarily in FIG. 6 with respect to the boundary 24. To this end before the thermal densification of the pourable intermediate substrate 6, 21 within the double-belt press 4 the laminar layer sequence of the dispersed layers in different colors are actively partially or almost totally destroyed in vertical and/or horizontal direction using mechanical measures, such as brush rollers or charging rakes or other suitable disturbing elements, thus generating color mixing effects within the planar formation that is generated, namely the dimensionally stable body 22. The granulate materials obtained therefrom then display very different color transitions within a single particle. By means of these particular granulates materials also in a final product, e.g. a thermoplastic web 19, novel design possibilities can be generated.

(30) According to a further embodiment of the method according to the invention the intermediate substrates disperse onto the lower belt 18 in one or more layers or gaps, respectively, the powdery mixtures 6 and 21, as well as also in the melting zone of the double-belt press 4, or only there, are shifted or mixed by means of disturbing elements once or several times with respect to their position with respect to each other. Such a disturbance within the melting zone in particular by the introduction of shear forces within suitable viscosity ranges leads to an improvement of the mechanical characteristics of the produced intermediate product, namely the dimensionally stable body 17 or 22, respectively, and thus finally of the granulate materials 11, 12 and/or 13.

(31) According to the invention the disturbing elements are preferably measures for vibrating, brushing, spiking, plowing, kneading and similar mechanical interaction. These disturbing elements are arranged together with and in coordination with the upper belt of the double-belt press 4 or are arranged in combination with the latter.

(32) Since during comminuting the web from the double-belt press 4 also a large amount of dust may be generated, it is preferred, if before the storage of the granulate material within the granulate storage 20 the granulate material is further sieved within a sieve device 8. The dust-shaped fine portions according to a further embodiment of the invention are fed back into the process, e.g. as fillers into the second mixer 3, e.g. when there shall be generated very dark color variants and thus the resultant color appearance is not impeded.

(33) A further aspect of the invention rests in the fact that the final product 19 must not be produced on a separate, second double-belt press 7, but also using the first double-belt press 4 used for the production of the granulate material. In this case the production of the granulate material and the production of the final products are performed with shifted time sequentially on the one double-belt press. Such a double-belt press to this end comprises supplementary modules (e.g. caster or other process-related units), which are utilized selectively with respect to the desired process, namely either with respect to the production of granulate materials or with respect to the production of final products.

(34) Another aspect of the invention according to a further embodiment of the novel method of producing the pourable intermediate substrate(s), again without the use of extruders, on a (first) double-belt press a patterned or a mono-colored web-shaped dimensionally stable body is produced, wherein this one or additional intermediate product(s) at the end of a double-belt press is not comminuted, but serves as a final web or only as a part thereof, in particular as an intermediate product for a web to be produced thereafter, which possibly may comprise further material coatings. According to a further aspect of the invention from the dimensionally stable bodies according to the invention any type of bodies may be produced as half-finished products or intermediate products by stamping, cutting, pressing or other suitable separating methods, to be used for producing a variety of products which may be close or more far off from the final products mentioned at the outset.

(35) The dimensionally stable bodies, i.e. the first intermediate product and the further intermediate product(s) within the scope of this invention may also be film-shaped bodies in extreme embodiments.

(36) It will be understood that afore-mentioned features of the invention may not only be used in the respectively given combination, but also in different combinations or independently, without leaving the scope of the invention.

REFERENCE NUMERAL LIST

(37) 1a, 1b . . . 1n container (for pos. 9a, . . . 9n) 2 first mixer (heating mixer) 3 second mixer (cooling mixer) 4 double-belt press (Thermofix press) 5 comminutor (chopper, mill or similar device) 6. intermediate substrate (powdery mixture, pourable) 7 further double-belt press (for final product) 8 sieve device 9 starting materials 9a first plastic powder 9b second plastic powder 9c first additives 9d second additives 9e first plasticizer 9f second plasticizer 9g first color materials 9h second color materials 9i first lubricant 9j second lubricant 9k first fillers 9l second fillers 9m first additives 9n second additives 10 tubing system 11 first granulate material 12 second granulate material 13 third granulate material 14 (not used) 15 first heating/cooling mixer 16 second heating/cooling mixer 17 first intermediate product (dimensionally stable body) 18 lower belt (of pos. 4) 19 thermoplastic web (final product) 20 granulate storage 21 further intermediate substrate (powdery mixture, pourable) 22 further intermediate product (dimensionally stable body) 23 component (for pos. 19) 24 boundary layer