CA1316321C

CA1316321C - Method for producing coloured, homogeneous surface-structures from thermoplastic synthetic materials

Info

Publication number: CA1316321C
Application number: CA 526295
Authority: CA
Inventors: Alexander Hover; Manfred Simon; Richard Weiss
Original assignee: Dynamit Nobel AG
Current assignee: Dynamit Nobel AG
Priority date: 1985-12-27
Filing date: 1986-12-24
Publication date: 1993-04-20
Anticipated expiration: 2010-04-20
Also published as: ES2027223T3; JPS62160211A; DE3682881D1; EP0227029B1; ATE70216T1; EP0227029A3; DE3546215A1; DE3546215C2; EP0227029A2

Abstract

ABSTRACT OF THE DISCLOSURE:

A method for producing coloured, homogeneous surface-structures from thermoplastic synthetic materials, wherein an initial mixture, based upon thermoplastic synthetic materials, is processed, by thermal pretreatment above the softening temperature, into an agglomerate or granular material and, after any necessary intermediate steps, is mechanically comminuted into a granular mixture having any desired grain-size distribution. The granular mixture of freely flowing particles is shaken continuously onto a conveyor-belt in a uniform layer and is sintered, under the action of heat, until the thermoplastic material plasticizes, to form a coherent surface-structure, being then compressed under the action of pressure and heat.

Description

:L31~32 ?

The present invention relates -to a process for the production of dyed, homogeneous flat articles based on thermoplastic synthetic resins wherein particles of thermoplastic synthe-tic resins are sintered in-to a coherent flat article, such as a sheet and the article is then press-molded under the action heat and pressure and wherein the starting material for forming the particles is obtained from resin preheated above the softness temperature of the resin.
Unicolored, homogeneous flat articles made of a thermoplastic synthetic resin, especially made of poly-vinylchloride (PVC), in the form of sheets or panels, with thicknesses of above 1 mm, can be manufactured according to the state of the art by means of extrusion, spread-coating, or rolling methods, resulting in a unicolored, homogeneous molded article conveying, as an inherent design feature, a cold plastic look and a typical plastic image. Even mixtures of various granulated compositions and their processing by means of the extrusion or rolling technique, though providing a color differentiation corresponding to the colors utilized, have not contributed toward lifting the cold feeling inherent in plastic. However, especially when using sheets or panels as floor coverings and wall coverings, special emphasis is placed on esthetic impression. In this connection, it is an object of the invention to create flat articles of thermoplastic synthetic resins conveying an esthetically pleasing optical impression and lending themselves optionally to random patterning.
A process has been known from U.S. Pat. No.
3,381,067 for the manufacture of terrazzo-type floor coverings wherein granules having a diameter of 6-12 mm and a thickness of 44-800 ~um are produced from a plasticized PVC
with fillers and colorants and s-tabilizers, and coated with a plasticized PVC paste, then piled up into a uni~orm layer, heated, sintered, and press-molded into a continuous sheet - 1 - ~

.,.................. ~ .

.

13~ 2~.
with the use of pressure and heat. By u-tilizing dif-ferent compositions for the granules and the coating s-tep, a covering is produced wherein the granules are embed~ed in a softer shell; i.e. a covering exhibiting differing wear characteristics.
U.S. Pat. No. 3,192,294 discloses a process of the type for the production oE floor coverings having a multicolor effect, for example pepper-and-salt patterns, wherein preferably compositionscontaining PVC, plasticizer and blowing agent in powder form are piled up into a layer and heated to such a degree that the layer is sintered into a coherent sheet which is then expanded by decomposition f the blowing agent, whereafter the sheet, while passing through a roll nip, is embossed on the topside with a relief occupying, e.g., one-half or more of the sheet thickness.
The PVC composition is prepared as a dry blend, i.e. mixed in the cold state (also in order to avoid premature decomposition of the blowing agent), and the particles exhibit an average size of 15 ,um to about 3 mm, using in each case a uniform particle size, for example, of 15 ,um.
It is also possible to furthermore add proportions of very small particles of 2 ,um made of a copolymer, but this can be very disadvantageous if the fine proportions are separated, i.e. fall through toward the bottom, and the coarse particles form an uneven surface.
The floor coverings produced in accordance with U.S. Pat. No. 3,192,29~ with thicknesses of about 2.5 mm are prone to cracking on account of their strong surface embossing, and thus require additional surface protection in the form of an additional film coating. Furthermore, the particle structure i8 shifted due to the vigorous embossing, so that elongated, nonuniform zones are formed.
U.S. Pat. No. 3,359,352 and German Pat. No.
1,298,023 describe a process for the production of a -" ?~
`?~

, J .~,.

decora-tive, multiple layer coveri.ng wherein particles having a grain size of abou-t 2.5 ~Im to 0.013 mm, produced by mixing PvC powder and plasticizer as well as additives a-t ~emperatures of about 93C, i.e. well below -the sintering S temperature of the synthetic resin, are piled up on a substrate sheet serving as the support to form a la~er and are sintered into a porous sheet. These particles, produced at low temperature far below the plasticizing tempera-ture of the synthetic resin, also called dry blends, are soft and do not show high firmness and dimensional rigidity since they have not been plasticized. During the subse~uent press-molding step, the particles thus deliguesce and, when using differently colored particles, result in mixed colors or in deliquescing color contours with an orientation in the lS rolling direction. It is necessary in this conventional method to utilize a support material as the substrate layer homogeneous flat articles, i.e. layers showing a design throughout without a substrate layer, conse~uently cannot be manufactured.
One object of the invention homogeneous flat articles havinga fine-textured, random design.
According to the present invention, there is provided a process for the production of flat articles, having a fine-textured, random design, comprising:
- processing a starting material for forming particles of a thermoplastic synthetic resin by a thermal pretreatment above the softening temperature of the resin into an agglomerate or granular mixture, - mechanically comminuting the mixture into a fine mixture of particles having a random grain size distribution, and - conveying said fine mixture of particles in a uniform layer and sintering it under the action of heat up until plastici2ation of the thermoplastic plastics to form a ., ~L3~2~

coherent fla-t article and then compressiny the coheren-t flat article under -the action of pressure and hea-t.
According to the present invention, there is also provided a process for -the production of multicolored, homogeneous flooring sheets made of -thermoplastic synthetic resin wherein pourable particles are continuously forrned into a uniform layer and are sintered under the action of heat up to the plasticization of the thermoplastic synthetic resin to form a coherent, porous layer and the porous layer is press-molded under the ac-tion of pressure and heat to form a flooring sheet that is void-free and smooth, and wherein several colored batches of thermoplastic resin are formed, with each batch having a color different from -the other: each batch is then heat-treated above the softening point of the thermoplastic resin and is formed into colored agglomerates or colored granules; a blend of differently colored agglomerates or granules is prepared in a predetermined mixing ratio; the blend is mechanically comminuted to form the pourable particles which comprise a multi-colored mixture of particles having a random grain size distribution and, thereafter, the pourable particles are continuously applied directly to a conveyor surface to form the uniform layer which is subsequently sintered to form the porous layer.
According to the present invention, there is also provided a process for the production of multicolored, homogenous flooring sheets made of thermoplastic synthetic resin wherein pourable particles are continuously formed in-to a uniform layer and are sintered under the action of heat up to the plasticization of the t~ermoplastic synthetic resin to form a coherent, porous layer; then at least one colored medium is appliéd ~l~n~ a predetermined pattern penetrating into the coherent porous layer and the porous layer is press-molded under the action of press~re and heat ~ . . . .

~ ' ,.~ ' .

~ ut ~

-to form a flooring sheet -that is void-free and smooth, and wherein several colored batches of thermoplastic resin are formed, with each batch having a color different from the other; each batch is then heat treated above the softening point of the thermoplastic resin and is formed into colored agglomerates or colored granules; a blend of differently colored agglomerates or granules is prepared in a predetermined mixing ra-tio; the resulting blend is mechanically comminuted to form the pourable particles which comprise a multi-colored mixture of particles having a random grain size dis-tribution and, thereafter, the pourable particles are continuously applied directly -to a conveyor surface to form the uniform layer which is subsequently sintered to form the porous layer.
According tc a preferred embodiment there is provided a process wherein a batch of thermoplastic synthetic resin is prepared from a PVC composition ~ .
.~-, . , - - - :

~3~321 containing:
- 40-60~ by weight of PVC having a K-value of 50-80:
- 18-Z~% by weight of plasticizer based on phthalic acid esters, - 20-40% by weighk of a filler including calcium carbonate, and - 0.5-2~ by weight of stabilizer based on at least one of a barium-cadmium, a calcium-zinc and a tin compound;
thereafter, separating the batch into smaller batches, with each smaller batch being admixed with 0-3% by weight oE a colorant to provide a plurality of differently colored smaller batches, thereafter, plasticizing the smaller batches at temperatures above the softening point of ~he PVC
and forming each smaller batch into granules or agglomerates.
Even with the use of particles dyed in one color, i.e. unicolored, of a grain mixture of arbitrary or random grain distribution, a polychrome, differentia-ted coloring is obtained. An infinite variety of color and texture nuances is made possible with the use of only a few different particles oE a multicolored design and by means of a differing mixture proportion in the mixture with respect to grain size and grain distribution.
The thermally pretreated particles utilized accoxding to this invention exhibit a firm grainy structure, as contrasted with dry blends, and this grainy structure remains preserved during sintering and does not deliquesce.
According to a preferred embodiment of the invention, particles produced by abrading, forming a mixture of various grain sizes in random distribution, are used for the manufacture of sheets or panels. It is possible, for example, to grindoff, with a grinding belt of a specific coarseness, differently colored panels or sheets of a PVC

~ 6 -:: `

.
. . .
, , .
. " .
.

~3~3~

composition containing plastici~er, fillers, stabilizers, pigments, etc. used, for example, as ~loor coverings, thus obtaining a grinding dust havinga granular size of, for example, 0.1-2 mm, initially appearing -to be unicolored to the naked eye. ~y applying this grinding dust, for example by way of a hopper with a doctor blade adjustable at -the front side, onto a conveyor belt, e.g. separating paper or a steel band, continuously moving thereunder, and by allowing the piled-up grinding dust then to sinter superficially under an infrared (IR) field or in a heating tunnel, and by thereafter bringing this material to a temperature range required for plasticizing, this superficially sintered rough sheet can then be molded under pressure into a homogeneous, void-free sheet or panel showing a design extending throughout its total thickness. Suitable conveying belt materials are -those from which the sheet can be pulled off again without difficulties, such as release paper, "Teflon"*
coated fabrics, or also metal belts, such as a steel band, for example. The heat energy required for sintering can be provided by way of IR radiators, hot air, or also in a high-frequency field, and the final compression step can take place continuously via rolling mills, single-belt presses, or preferably twin-belt presses. Depending on the surface structure of the rolls or belts, corresponding surfaces can be embossed. Panels can be punched out from the sheets if desired. It was surprinsingly found, in this connection, that there evolves from a originally unicolored grinding dust a polychrome, finely textured, brilliant design no longer exhibiting the plastic look of coldness and uniformity which heretofore had been the rule.
This process of the invention can be varied, by the use of only a few different, multicolor-design rough sheets and by a differing the mixing proportions of the grinding dusts derived therefrom, in such a way that an *Teflon is a Trade mark .

~3~3~

infinite number oE color and -tex-ture nuances become possible. Preferably, grains or particles produced by abrading of a preformed resinous article such as a sheet or panel are utilized in a grain mixture wherein -the propor-tion of grain size of 250-800 ~m constitutes 60-90% by weight of the mixture comprising the starting material for forming the particles to be compressed into a sheet.
It has furthermore been found, surprisingly, that an analogous polychrome uni-design is obtained by using, in place of grinding dust, agglomerates likewise dyed in different colors, for example having been brought to a specific temperature by fric-tion in a mixer and being applied in varicolored blends. It is furthermore possible to change the character of the agglomerates in regard to structure by means of a grinding step following the mixing step. Moreover, blends of abrasion dust and agglomerate are also possible, along with combinations of filled and unfilled systems, i.e. PVC compositions with and without a filler; by use of transparent synthetic resin particles, a three-dimensional effect is conveved above and beyond the polychrome character. Such polychrome, homogeneous-panels or also sheets, however, can be produced not only from grinding dust, agglomerate, but also from reclaim material consisting of varicolored edge strips which were chopped and ground. In the same way, a similar effect can be obtained by way of the sinter-pressing method from correspondingly dyed granules which have been ground up. Likewise, mixed PVC
powder with additives can be plasticized by way of a plasticizer or extruder and processed into granules or chips or pellets, and these can be ground by means of mills to the desired fine grain, i.e. a fine grain mixture. The PVC
compositions can be made to be transparent, unicolored, or also varicolored mixtures of differently colored dusts and grain sizes can be utilized. This results, after press-., ~

1 3 ~

molding, in a brilliant, finely resolved, multicolored basic tone without direc-tional orientat:ion. Also the yrain size and grain distribution of the par-ticles employed cause a muted to distinct appearance of the pattern as a fine or also coarse texture, or create small to large resolution capacity.
Mixtures of the agglomerates are preferably utilized which are produced by mixing a PVC composition at mixing temperatures of up to about 170C, generated by frictional heat, with subsequent cooling and grinding and optional screening. Such a mixture of agglomerate, leading to a design of an especially pleasing appearance, has, for example, a proportion of about 20 to 75% by weight of the grain size of 500-2,000 ~m in the mixture.
According to this invention, the texture of the sheet and thus the pattern, i.e. the polychrome impression, can be varied by changing the shape of the particles, whether produced in grain form, by abrading or by grinding to differing size.
According to another aspect of this invention, the particle may be obtained by grinding up agglomerate granules, in this connection, 1, 1.5, or 2 mm screens can be utilized, for example, for the screening step. All of these mixtures produced by grinding contain thermally pretreated particles which had already been plasticized once and thus result in a firm grain structure. Thermal pretreatment took place, for example, during the manufacture of the agglomerate or during extrusion of molded elements subse-~uently processed into granules, chips, edge strips, waste, and forming the starting material for the grain mixtures to be produced and utilized in accordance with this invention.
A mixture of particles of different origin, for example from grinding processes, preferably contains a proportion of the grain size of 500-2,000 um of about 30-95%

_ g _ .

1 3 ~

by weigh-t.
It is moreover possible to utilize blends or particles from various origins, colorings, structures, and/or grain distribution.
The polychrome color image may be obtained according to this invention especially by using mixtures of particles with a grain dis-tribution wherein each screening fraction is present at least with a minimum proportion of 0.1% by weight, and no screening fraction is present at a proportion larger than 50% by weight.
Sheets or panels having an especially fine and uniformly random design are obtained by using, according to a further suggestion of the invention, grain mixtures containing 80-98% by weight of grain sizes from 300 to 800 ym.
According to a further preferred embodiment of the invention, flat articles to be utilized especially as floor and wall coverings are obtained with the use of a process wherein a PVC composition containing PVC, plasticizer, an inorganic stabilizer, and a colorant is plasticized above the soEtening temperature of the resin to form a molded component and the molded component is comminuted into the particle mixture.
In this process, transparent, translucent up to completely colored-through sheets are obtained.
The process for producing the flat articles is~
preferably performed by piling the mixture of the particles~
up into a layer having a thickness of preferaby about 5-12 mm, and heating to temperatures up to about 210C and sintering, and then press-molding, with a surface pressure in the range from 0.2 to 20 N/mm or, respectively, a corresponding linear pressure in the roll nip, homogeneously into a sheet or panel having a final thickness of about 1.5-4 mm.
~ :

:~ ' ::

:: ~

, 131~3'2,~
For the production of filled sheets or panels, -the process can be carried out, according to another embodiment of the invention, wherein the polyvinyl chloride composition is provided with fillers such as calcium carbonate and then processed into the particle mixture.
Such homogeneous sheet or panel material of polychrome design can preferably be utilized as floor or wall covering and is predestined for use especially where abrasion or wear represent a dominating problem. Such a covering, homogeneous with respect to its struc-ture, can wear down over the entire thickness without a change in pattern and texture.
The process of this invention provides a live and also three-dimensional appearance attaining mono- to lS polychrome effects in dependence on the given coloration, A
particular spatial, three-dimensional effect is achieved by a transparent basic material for a portion of the particles in which particles of another color can be embedded.
This process technique according to the invention exhibits the additional advantage, besides a novel design possibility, of not only reprocessing dyed, thermoplastic products obtained as waste in a recycling step by simple means, but also of refining these products into novel, high quality goods, thus expanding the previous state of the art and enriching the array of homogeneous floor coverings with respect to texture and feel.
The thermoplastic synthetic resin useful for purposes of this invention includes not only PVC but also copolymers of vinyl-chloride with vinyl acetate, ethylenevinyl acetate, and optionally acrylate polymers which can be used individually or in mixtures.
In addition to PVC, other thermoplastic synthetic resins, for example based on ethylene-vinyl acetate, can also be processed into flat articles according to this 1 - 1 1 ~
` .

''. ~ ' - '' ' . " .

~3~&~
invention.
According to one embodiment of the invention, particles produced by abrading, consti-tuting a rnix-ture of different grain sizas in random distribution, are used for the manufacture of sheets or panels. It is possible, for example, to abrade panels or sheets dyed in different colors made up of a PVC composition with plasticizer, fillers, stabilizers, pigments, and used, for example, as floor coverings, by means of an abrasive belt of specific coarseness. The result is an abraded dust which initially appears unicolored to the naked eye and has a grain size o~, for example, 0.1 to 2 mm. If this abraded dust is applied for example, by way of a hopper with a doctor blade adjustable at the front side, onto a supporting belt, e.g.
lS release paper or a steel band, moving continuously therebeneath, and then the thus-piled up abraded dust is superficially allowed to sinter under an infrared ~IR) field or in a heating tunnel, then a porous layer is obtained which can be provided with a design throughout and can subsequently be shaped under pressure into a homogeneous, void-free sheet or panel carrying a continuous design over the entire thickness, the structure of the pattern not being blurred or distorted.
This process according to the invention can be varied by using rough sheets with a multicolor design that is only a,little different, and by a different mixture proportion and the thus produced abraded dusts, in such a way that infinitely many color and texture nuances are possible. preferably, grains or particles produced by abrading are utilized in a grain mixture wherein the proportion of grain sizes of 250-800 jum constitutes 60-90 by weight of the mixture.

.i , ~3~2~.

Suitable conveyor belt ma-terials are those permitting the finished sheet to be pulled off again withou-t any di-fficulties, such as release paper, "TEFLON" coated fabric, or also metallic belts, such as steel band. The thermal energy required for sintering can be provided by means of IR radiators, hot air, or also in a high frequency field; the subsequent compressing step can take place * Teflon is a trade mark . . ~ , . ~ , .. . . . . .

, , :. ' , ~ 3 ~
continuously by means of rolling mills, single-belt or twin-belt presses. Depending on the surface texture of the rolls or belts, corresponding surfaces can be embossed; the embossing depth can amount preferably up to about 100 ym or also more.
The invention will be described in greater detail below wi-th reference to the accompanying drawings and examples.
Fig. 1 shows a schematic view of a sintering apparatus with a pair of pressure rollers;
Fig. 2 is a schematic view of a belt press;
Fig. 3 is a schematic view of a twin-belt press;
Figs. 4-12 show various surface designs corresponding to different grain mixtures.
A conveyor belt 1 rotating endlessly over two guide rollers 18,19, of which at least one is driven, is utilized for the continuous processes according to Figs. 1, 2 and 3 as the support means. Preferred materials for the conveyor belt l are release paper, steel, or also "TEFLON"*
(polytetrafluoroethylene) belts. By way of the hopper 2 having an adjustable doctor blade 3, the grain mixture 4 to be applied is piled up on the conveyer belt 1 in dependence on the desired final -thickness of the flat article, preferably in a thickness of 5-12 mm. Other application systems can also be utilized, for example metering chutes.
This layer 40 is then continuously heated under, for example, an infrared heater 5 and/or a heating tunnel 6, up to the plasticizing temperature, and sintered to form a continuous flat sheet 41. During this sintering step, the layer 40 loses some volume, and the thickness is reduced correspondingly to about 4-10 mm. Subsequently, the sintered sheet 41 passes through a pressing station, for example an embossing unit, consisting of a metal roll 8 and a rubber roll 7, compressing the sheet 41 and superficially * Teflon is a trade mark , . ~ .

~ 3 ~ fi 3 ~J 1 smoothing same, or also providing same with a texture.
Thereafter, the final product 42 leaves the installation and is passed on to finishing.
Advantageously, a belt press can be used for compressing the sintered sheet ~1, as illustrated in Fig. 2;
the belt endlessly rotating over the guide rolls 10, 11, 12 is guided so that it urges the sintered sheet against the roll 9 over a predetermined route. The sheet, after cooling is removed from belt 20 as the finished sheet 42.
Especially advantageously, a -twin-belt press is utilized for the compressing step, as schernatically illustrated in Fig.

3, this press operating with two belts endlessly rotating over guide rollers 10, ll and 1~, 13, respectively, the sintered sheet 41 being thereby pressed alterna-tingly against the roll 9 and, respectively, roll 15 and, after cooling and compressing, is taken off the belt 20. The surface of the sheet ~2 can be finished either within the belt press or also, for example, by means of an embossing station arranged downstream thereof, or also by means of an abrading and/or polishing step.
The examples set forth below represent embodiments of the process of this invention as illustrated in Fig. l, and of the production and use of the grain mixtures.

a basic batch is first of all mixed from filled plasticized PVC, with the following proportions:
31 parts by weight of PVC "Vinnol* Y 68 M"
(company: Wacker-Chemie) 13 of dioctyl phthalate 25 of chalk 0.15 of stabilizer based on Sn, and respectively 70 parts by weight of this batch is * Vinnol Y 68 M ls a trade mark .~ .

2 ~

combined separa-tely with -the coloring pigments set forth below and is granulated after mixing by means oE an extruder:

5 Color Number Color: Parts by Weight:

1 Medium brown 0.7 2 light brown 0.987 3 beige-greenish 1.337 4 dark brown 0.252 ... . _ _ . . . . . .. _ _ Extrusion temperature 170C, granule diameter 4-5 mm.
The granules are then once again mixed in the following weight rations: color number 1:2:3:4=1:1:1:0.76, and processed by means of extruder and rolling mill into a marbled sheet material. During cal.ibrating by abrading with belts of number 50 and number 100 abrasive gr~in, an abrasion dust is obtained having the following grain distribution (wet screening):

mm .. .. _ .. _ _ _ 0.04 0.7 0.04 -0.063 0.4 0.963-0.1 0.2 0.1 -0.125 0.9 0.125-0.2 2.0 0.2 -0.25 7.8 0.2 -0.315 . 16.4 0.315-0.5 35.5 0.5 -0.8 32.5 0.8 -1.0 3.1 1.0 -1.6 0.4 1.6 -2.0 0.1 . _ , .. .
~i - 16 -~ 3 ~

The thus obtained grinding dust is applied via a hopper with level-adjustable doctor blade with a gap set-ting of 5 mm onto a release paper sheet, see Fig. 1, and superficially sintered under an infrared radiator having a length of 0.6 (7.5 kW) and through a hot-air tunnel having a length of 6 m, at temperatures of 160-205C and at a rate of lm/min.
The sintered sheet can thereafter be continuously compacted and embossed in one operating step by way of infrared radiators and an embossing roll unit -to form polychrome, compact uniform covering having a thickness of 2 mm.

_ _ The grinding dust obtained according to Example 1 is mixed in a proportion of 1:1 with a grinding dust B
obtained from a different color combination and produced in the following composition: :
Parts by Weight Color Number Color: (per 70 parts of basic batch according to Example 1):
: -dark greyish brown 0.24 6 dark reddish brown 0.45 7 medium brown 0.4 8 beige-reddish 1.0 -The mixture had the granule ratio of: color number 5:6:7:8=1:1:1:0.76.
The grinding dust had the following grain structure:

-~ ~

:

13~ ~3~:~

. .
mm %

0.04 0.9 0.04 -0.063 0.2 0.063-0.~ 0.2 0.1 -0.125 ~.0 0.125-0.2 3.9 0.2 -0.25 10.3 0025 -0.315 16.3 0.315-0.5 42.7 0.5 -0.8 23.5 0.8 -0.1 0.8 1.0 -1.6 0.1 1.6 -2.0 0.1 .
The grinding dust mixture A+B from two sheets dyed with different marbling, with a total of 8 basic colors, is sintered analogously to Example 1 and, after cooling, is punched outand press-molded under the action of a press at a temperature of 150C to a homogeneous sheet having a thickness of 2 mm and exhibi-ting a brilliant polychrome mixture.

From the sheets produced according to Example 1, edge strips can be cut off, comminuted into chips having a size of 5-10 mm, and ground in an "Alpine*" mill with a 2 mm size screen. The sheets and panels sintered and compressed from the ground reclaim analogously to Example 1 likewise yield, in dependence on -the grain size and grain distribution, a polychrome texture, the appearance of which, when viewed close-up, as also in case of Examples 1 and 2, * Alpine is a trade mark , .. . .

, ~ 3 ~

is not orien-ted nor strictly bounded and, from afar, have the effect of live unitary structures with respect to their charac-ter.

mm 0.04 0.9 0.04 -0.063 1.0 0.063-0.1 1.2 0.1 -0.125 1.4 0.125-0.2 1.6 0.2 -0.25 1.2 0.25 -0.315 1.4 0.31~-0.5 4.8 0.5 -0.8 10.7 0.8 -1.0 11.8 1.0 -1.6 22.4 1.6 -2.0 41.6 .

A polychrome uniform covering can also be produced, just as of grinding dust and ground reclaim, from the primarily produced granulated composition. The mixture, prepared in correspondence with Example 1 in 4 colors, was separately plasticized in an extruder, and granules having a size oE 4-5 were produced therefrom, and likewise the mixtures prepared according to Example 1 in 4 colors. Both granulated materials are mixed 1:1, comminuted in an "Alpine*" mill with a 2 mm screen, and applied to a metal belt in a thlckness of about 5 mm, sintered, and subsequently press-molded in a press into a sheet at a temperature of 150C. Here, too, with only two basic ' * Alpllle lS a trade mark , .... .. ~ .. .. .. .. .. .
: ~:

, ~.3~32~

colors, a polychrome color differentiation is attained.
The grain distribution was:

mm 0.04 1.0 0.04 -0.063 0.5 0.063-0.1 0.8 0.1 -0.125 1.3 0.125-0.2 1.6 0.2 -0.25 1.2 0.25 -0.315 1.3 0.315-0.5 3.8 0.5 -0.8 8.8 0.8 -1.0 11.5 1.0 -1.5 24.6 1.6 -2.0 43.6 The processing of this invention can be performed not only with plasticized material, such as granules, reclaims or abraded dust, but also with agglomerate that can be manufactured during the mixing process in a controlled fashion.
PVC "Vinno~ P 70", plasticizer, chalk, s-tabilizer are mixed in accordance with Example 1 with separate addition o~ the coloring pigments in a powder mixer with rotor, and heated by frictional heat to 140C, and cooled under agitation in a separate vessel and thereafter passed through an "Alpine*" mill with a 2 mm screen.
The four differently dyed agglomerate batches are mixed in the following proportion:

s * Vinnol P 70 is a trade mark .. : ~-.
. .

, , . ~ . :
. .
~, ~

~ ~63~

color number 1:2:3:4=1:1:1:0.76, and processed on a continuous conveyor as shown in Fig. 1 in correspondence with Examples 1-4 into polychrome uniform sheets.
The grain distribution was:

mm %

0.04 3.1 0.04 -0.063 lO.1 0.063-0.1 16.4 0.2 -0.125 6.2 0.125-0.2 8.6 0.2 -0.25 4.1 0.25 -0.315 3.5--l~ 0.315-0.5 7.3 0.5 -0.8 9.6 0.8 -l.0 7.3 l.0 -1.6 13.4 1.6 -2.0 10.4 In correspondance with Example 5, an agglomerate ~5 is produced without adding filler and dye, in a transparent grade. The 4-color agglomerate mixture produced according to Example 5 is mixed with the filler-free agglomerate in a rotio 1:1, applied to a "Teflon" belt in a thickness of 6 mm, superficially sintered, and continuously compacted in a belt press, thus obtaining a polychrome covering with depth effect.
The grain structure was:

. ~ :
- 21 ~

' ' ~c~

mm 0 04 0.2 0.04 -0.063 1.2 0.063-0.1 3.2 0.1 -0.125 3.2 0.125-0.2 6.9 0.2 -0.25 5.4 0.25 -0.315 5.7 0.315-0.5 14.4 0.5 -0.8 17.2 0.8 -1.0 10.8 1.0 -1.6 15.7 1.6 -2.0 16.1 The abraded dust described in Example 1 is mixed with the reclaim ground in Example 3 and the grain mixture ground Erom granules in Example 4, in a ratio of 2:4:4, and processed analogously to Example 6, thus obtaining, in spite of the differing grain structures and platicizing stages within the blend, a brilliant and clear polychrome appearance.
The graln structure was:

, ' , .

~L3~2 mm %

0.04 0.6 0.0~ -0.063 0.5 0.063-0.1 0.6 0.1 -0.125 1.2 0.125-0.2 2.0 0.2 -0.25 3.3 0.25 -0.315 5.3 0.315-0.5 13.0 0.5-0.8 24.6 0.8-1.0 18.2 1.0-1.6 14.6 1.62.0 16.1 _ __ 69 parts by weight of "Escorene* UL 00728"
(company: ESSO)( ).
30 parts by weight of "Juraperle* MHM"(company:
Ulmer Fuellstoffe)(2) 1 part by weight of color pigment-dye mixture _ _ 1) Ethylene-vinylacetate copolymer with about 28~ of vinyl-acetate 2) Chalk.

"Escorene UL 00728" was preplasticized at 120C in a rolling mill, then filler and color mixture were added in portions within 5 minutes, and rolling was continued for 10 mi~nutes. The the rolled sheet was taken off and * Escorene UL 00728 i8 a trade mark * Juraperle MHM lS a trade mark - 23 _ : ' ~

:' ' , , ~ ~

-- --preliminarily comminuted in the warm condi-tion into sections of about 6X6 cm. The cooled-off sections were ground on a cutting mill with a 1.2 mm screen.
The grain distribution was:

mm %
-0.25 5.5 0.25 -0.315 1.0 0.315-0.5 5.5 0.5 -0.8 16.7 0.8 -1.0 25.1 1.0 -1.25 34.2 1.25 -1.6 11.7 lS 1.6 -2.0 0.3 The resultant grain was mixed with a differently pigmented material, produced in the same way, in a ratio of 1:1:1:1. Thereafter, the premix is applied with a doctor blade onto a steel belt with a thickness of 6 mm and sintered. The sintered sheet, reduced in thickness to about 4 mm thereby, molded in a twin-belt press at a temperature of 110C into a polychrome sheet having a thickness of 2 mm.

The sintered sheet produced according to Example 1 can likewise be produced in one working step by way o~
in~rared radiators and a smoothing roll unit continuously into a polychrome, rough, nonslip covering having a thickness of 3 mm, with a lesser amount of compacting by a corresponding calibration in the roll nip. A covering is thus obtained showing a depth e~fect and having a special . ~

- 24 _ ' ':

~31~

textile appearance.
Analogously, the sintered sheet produced in accordance with Example 8 can be calibrated by way of a roll nip, thus producing a nonslip, polychrome covering.
Figs. 4 through 12 show designs of floor coverings that can be obtained in accordance with the examples. 1'he black-white reproduction fails, of course, to convey the colored impression, but the fine texturing can be recognized at least in its basic traits, even though -the color nuances are lost.
The thus produced sheets or panels exhibit a design not only on the surface but have such design throughout the entire thickness of the sheet, so that with wear and abrasion during use the surface design is not lost.
Fig. 4 shows a top view of a finished product made up of four different agglomerates according to Example 4, but with different grain distribution.
FigO 5 shows a top view of the sintered sheet according to Example l in a 1.3-fold magnification, and Fig.
6 shows a top view of the finished product according to ExampIe 1, i.e. the compacted sheet.
Fig. 7 is a view of the finished product according to Example 3.
Fig. 8 is a view of a finished product according ~5 to Example 2, but with only two differently coloured granular materials.
Fig. 9 is a view, enlarged x 1.3, of a sintered strip made from grinding dust of one colour. The open-pore structure of the sintered strip is easily recognizable.
Fig. 10 shows the finished product according to Example 5.
Fig. 11 is a view of the finished product according to Example 6, with an agglomereate containing transparent material.

':

Fig. 12 is a view of the finished product according to Example 7.
The surfaces of the compacted sheet or strip may be further refined, for example by embossing (smooth) or by very slight profiling -to a maximal depth of 100 ~m.

.

.

Claims

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. Process for the production of flat articles, having a fine-textured, random design, comprising:
- processing a starting material for forming particles of a thermoplastic synthetic resin by a thermal pretreatment above the softening temperature of the resin into an agglomerate or granular mixture, - mechanically comminuting the mixture into a fine mixture of particles having a random grain size distri-bution, and - conveying said fine mixture of particles in a uniform layer and sintering it under the action of heat up until plasticisation of the thermoplastic plastics to form a coherent flat article and then compressing the coherent flat article under the action of pressure and heat.

2. Process according to claim 1, wherein:
- as said starting material use is made of unicolored particles of a grain mixture of arbitrary or random grain distribution, and - as an end result a polychrome, differentiated coloFed article is obtained.

3. Process according to claim 1, wherein:
- as said starting material, use is made of a predetermined number of different particles of a multicolored design, and by means of differing mixture proportionsin the mixture with respect to grain size and grain distribution an infinite variety of color and texture nuanced article is obtained.

4. Process according to claim 3, wherein:
- particles produced by abrading, forming a mixture of various grain sizes in random distribution, are used for the manufacture of sheets or panels.

5. Process for the production of coloured, homogeneous flat shaped articles based on thermoplastic plastics in which a granular mixture of tricklable particles is obtained by comminution of moulded articles which are distributed in a uniform layer and sintered under the action of heat up until plasticisation of the thermoplastic plastics to form a coherent flat article and then compressed under the action of pressure and heat, thus obtaining articles which are patterned in many colours.

6. Process for the production of multicolored, homogeneous flooring sheets made of thermoplastic synthetic resin wherein pourable particles are continuously formed into a uniform layer and are sintered under the action of heat up to the plasticization of the thermoplastic synthetic resin to form a coherent, porous layer and the porous layer is press-molded under the action of pressure and heat to form a flooring sheet that is void-free and smooth, and wherein several colored batches of thermoplastic resin are formed, with each batch having a color different from the other; each batch is then heat-treated above the softening point of the thermoplastic resin and is formed into colored agglomerates or colored granules; a blend of differently colored agglomerates or granules is prepared in a predetermined mixing ratio; the blend is mechanically comminuted to form the pourable particles which comprise a multi-colored mixture of particles having a random grain size distribution and, thereafter, the pourable particles are continuously applied directly to a conveyor surface to form the uniform layer which is subsequently sintered to form the porous layer.

7. Process according to claim 1, 2, 3, 4, 5 or 6, wherein the mixture of particles is obtained in the form of abraded dust by grinding off sheet material produced from the blend of agglomerates or granules.

8. Process according to claim 1, 2, 3, 4, 5 or 6, wherein the mixture of particles produced by abrading contains a proportion of about 60-90% by weight of particles having a grain size of 250 µm to 800 µm.

9. Process according to claim 1, 2, 3, 4, 5 or 6, wherein a mixture of particles having grain sizes up to 2 mm is obtained by fine grinding of granules or agglomerates.

10. Process according to claim 1, 2, 3, 4, 5 or 6, wherein colored agglomerates are used to form the mixture of particles.

11. Process according to claim 10, wherein a mixture of the agglomerates is obtained by mixing a PVC
composition at mixing temperatures up to about 170°C with subsequent cooling and grinding and screening.

12. Process according to claim 11, wherein the mixture of agglomerates contains a proportion of about 20-75% by weight having a grain size of 500-2000 µm.

13. Process according to claim 1, 2, 3, 4, 5 or 6, wherein the mixture of particles is obtained from granules by comminution and fine grinding and screenlng out a proportion of about 30-95% by weight of grain sizes of 500-2000 µm.

14. Process according to claim 1, 2, 3, 4, 5 or 6, wherein said mixture of particles has a grain distribution wherein each screening fraction is represented with a minimum proportion of about 0.1% by weight, and no screening fraction is represented with a proportion larger than 50% by weight.

15. Process according to claim 1, 2, 3, 4, 5 or 6, wherein said mixture of particles contains 80-98% by weight proportion of grain sizes from 300 to 800 µm.

16. Process according to claim 1, 2, 3, 4, 5 or 6, wherein a batch of thermoplastic synthetic resin is prepared from a PVC composition containing:
- 40-60% by weight of PVC having a K-value of 50-80, - 18-24% by weight of plasticizer based on phthalic acid esters, - 20-40% by weight of a filler including calcium carbonate, and - 0.5-2% by weight of stabilizer based on at least one of a barium-cadmium, a calcium-zinc and a tin compound;
thereafter, separating the batch into smaller batches, with each smaller batch being admixed with 0-3% by weight of a colorant to provide a plurality of differently colored smaller batches, thereafter, plasticizing the smaller batches at temperatures above the softening point of the PVC
and forming each smaller batch into granules or agglomerates.

17. Process according to claim 1, 2, 3, 4, 5 or 6, which comprises piling up from the mixture of particles a layer having a thickness of about 5-12 mm onto a supporting belt, and heating this layer to temperatures. of up to about 210°C, sintering, and then press-molding homogeneously to form a sheet or panel having a final thickness of about 1.5-4 mm under a surface pressure in the range from about 0.2 to 20 N/mm2, or under a corresponding linear pressure in a roll nip.

18. Process according to claim 1, 2, 3, 4, 5 or 6, wherein the thermoplastic synthetic resin comprises a copolymer based on ethylene-vinyl acetate.

19. Process according to claim 18, wherein the mixture of particles comprises multi-colored particles, differently colored particles and transparent particles.