Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B65—CONVEYING; PACKING; STORING; HANDLING THIN OR FILAMENTARY MATERIAL
  • B65D—CONTAINERS FOR STORAGE OR TRANSPORT OF ARTICLES OR MATERIALS, e.g. BAGS, BARRELS, BOTTLES, BOXES, CANS, CARTONS, CRATES, DRUMS, JARS, TANKS, HOPPERS, FORWARDING CONTAINERS; ACCESSORIES, CLOSURES, OR FITTINGS THEREFOR; PACKAGING ELEMENTS; PACKAGES
  • B65D1/00—Rigid or semi-rigid containers having bodies formed in one piece, e.g. by casting metallic material, by moulding plastics, by blowing vitreous material, by throwing ceramic material, by moulding pulped fibrous material or by deep-drawing operations performed on sheet material
  • B65D1/22—Boxes or like containers with side walls of substantial depth for enclosing contents
  • B65D1/26—Thin-walled containers, e.g. formed by deep-drawing operations
  • B65D1/28—Thin-walled containers, e.g. formed by deep-drawing operations formed of laminated material
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
  • B29C48/00—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor
  • B29C48/16—Articles comprising two or more components, e.g. co-extruded layers
  • B29C48/17—Articles comprising two or more components, e.g. co-extruded layers the components having different colours
  • B29C48/175—Articles comprising two or more components, e.g. co-extruded layers the components having different colours comprising a multi-coloured single component, e.g. striated, marbled or wood-like patterned
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
  • B29C48/00—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor
  • B29C48/03—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor characterised by the shape of the extruded material at extrusion
  • B29C48/07—Flat, e.g. panels
  • B29C48/08—Flat, e.g. panels flexible, e.g. films
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
  • B29C51/00—Shaping by thermoforming, i.e. shaping sheets or sheet like preforms after heating, e.g. shaping sheets in matched moulds or by deep-drawing; Apparatus therefor
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29K—INDEXING SCHEME ASSOCIATED WITH SUBCLASSES B29B, B29C OR B29D, RELATING TO MOULDING MATERIALS OR TO MATERIALS FOR MOULDS, REINFORCEMENTS, FILLERS OR PREFORMED PARTS, e.g. INSERTS
  • B29K2023/00—Use of polyalkenes or derivatives thereof as moulding material
  • B29K2023/10—Polymers of propylene
  • B29K2023/12—PP, i.e. polypropylene
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29K—INDEXING SCHEME ASSOCIATED WITH SUBCLASSES B29B, B29C OR B29D, RELATING TO MOULDING MATERIALS OR TO MATERIALS FOR MOULDS, REINFORCEMENTS, FILLERS OR PREFORMED PARTS, e.g. INSERTS
  • B29K2025/00—Use of polymers of vinyl-aromatic compounds or derivatives thereof as moulding material

Definitions

• the invention relates to a method for producing a plastic film, in which at least one layer is extruded, a heterogeneous mixture of at least two plastic materials being produced for at least one layer before the extrusion.
• the invention also relates to containers, in particular plates or cups, made of deep-drawn plastic film, which has at least one layer.
• Containers in particular cups made of deep-drawn plastic film, which is composed of several layers, are known.
• the outer layer is colored by adding so-called color master batches.
• containers produced in this way are of one color, so that the containers have to be subjected to further working steps after the thermoforming process in order to design them optically.
• the object of the present invention is to provide a method with which an at least single-layer extruded plastic film can be provided with a color structure in a simple and cost-saving manner. It is also an object of the invention to provide containers which have a different color and structure, without the containers having to be printed or laminated.
• the invention is based on known extrusion processes with which it is possible to produce single-layer or multilayer plastic films, it being possible for the layer or the layers to be colored.
• a blowing agent is added according to the invention before the heterogeneous mixture of the at least two plastic materials is extruded.
• the " plastic materials forming the mixture differ either in that one plastic material is transparent and the other plastic material is provided with color pigments or in that the plastic materials are colored differently.
• the plastic materials are preferably used as granules.
• the heterogeneous mixture is then heated to above the softening temperature of the plastic material, with the blowing agent being at least partially activated at the same time.
• Blowing agents are known additives which are usually used to foam plastics, e.g. Polystyrene or polypropylene can be used. At certain temperatures, these blowing agents form gases that cause the plastic to foam.
• blowing agents in cooperation with the colored plastic material, develop the property of at least partially preventing homogeneous mixing of the transparent and the colored plastic material or also of the differently colored plastic materials. This means that the heterogeneity of this mixture is largely preserved.
• the extent to which the heterogeneity of this mixture is maintained when heated above the softening temperature of the plastic material can be controlled via the amount of the blowing agent and the selected temperature.
• the material After the heating of the heterogeneous mixture and the at least partial activation of the blowing agent, the material is extruded while maintaining the heterogeneity.
• both single-layer films as well as co-extrusion multi-layer films are produced, preferably mixtures of colored and transparent material being used because this allows the color design options, in particular in the case of multi-layer films, to be increased.
• the extruded or coextruded film is colored in accordance with the colored plastic material used and additionally has areas of transparent or differently colored material embedded in this colored material, which can be referred to as a color matrix. It has been found that the greater the proportion of propellant selected, the larger these areas.
• a temperature in the extruder is preferably selected which is between 70 ° to 150 ° above the softening temperature of the plastic material used in each case.
• This color structure is changed to a greater or lesser extent when the film is deep-drawn to form a container such as a cup or a plate.
• Those transparent areas that are located in film sections that are stretched very much during the deep-drawing process are accordingly pulled far apart.
• the sections that are stretched very much during deep drawing have a more or less rough structure that bears a certain resemblance to a wood grain. Areas that are only slightly stretched during the deep-drawing process largely retain their initial structure.
• a color structure is thus obtained which has an essentially line-shaped or line-shaped shape in the highly stretched sections and rather shows a closed circular configuration in the less stretched sections.
• blowing agents are added as blowing agents, preferably endothermic blowing agents being used. Acid-carbonate systems, for example, can be used as blowing agents.
• the proportion of the blowing agent in the material forming the layer is 1 to 20% by weight.
• the amount of blowing agent depends on the temperature selected in the extruder and whether large or small transparent or differently colored areas with sharp or less sharp boundaries are desired.
• Polystyrene or polypropylene is suitable as the plastic material for the production of such extruded films.
• the proportion of the transparent plastic material is preferably 65-98% by weight, also based on the total amount of the layer.
• Table 1 the mean diameters of the transparent areas in the extruded and not yet deep-drawn film were evaluated. Polystyrene with a proportion of 71% by weight was used as the plastic granulate. The colored plastic material (colored polystyrene) has a share of 20% by weight. The proportion of the blowing agent is 9% by weight. As can be seen from Table 1, the mean diameter of the transparent areas increases from approx. 1 to approx. 3 mm with increasing extruder temperature. Table 1
• Plastic material PS, 71% by weight Colored plastic material 1 : PS, 20% by weight of blowing agent: 9% by weight
• PS color material blowing agent mean diameter of the transparent areas
• the layer structured by the transparent areas carries at least one further structured layer, the transparent areas of the structured layers at least partially overlapping. If, for example, a container is made from a four-layer film that has a white inner layer and differently colored structured layers (e.g. red, green, blue), the overlapping of the transparent areas results in a color pattern consisting of red, green and blue spots or Lines composed.
• a container is made from a four-layer film that has a white inner layer and differently colored structured layers (e.g. red, green, blue)
• the overlapping of the transparent areas results in a color pattern consisting of red, green and blue spots or Lines composed.
• this material is introduced into a further layer which is arranged between the inner layer and the first outer structured layer.
• this backing layer is only visible over the transparent areas of the structured layer.
• a transparent antistatic layer is preferably also applied to the outer structured layer. It is also possible to provide the outer structured layer with an antistatic material.
• Preferred thicknesses of the structured layers are 50-120 ⁇ m.
• the backing layer preferably has a thickness of 400 to 950 ⁇ m and the inner layer between 50 and 250 ⁇ m.
• Table 3 shows the composition of a four-layer coextruded film.
• Inner layer 180 Around color material white 2% polystyrene 98%
• blowing agents has the further advantage that, in addition to largely maintaining the heterogeneity of the mixture, a certain amount of foaming of the plastic material also takes place. Since the coextruded film lies with its structured layer on the deep-drawing tool, the surface is the structured layer almost completely smooth. Any thickening of the film due to the foaming effect of the blowing agent can therefore only lead to a certain roughness on the inner layer. This roughness of the inner layer enlarges the inner surface, which is particularly advantageous when used for yoghurt cups because it ensures a certain fixation of the filled material.
• the roughness of the inner layer is essentially due to the remaining proportions of the blowing agent which have not yet been activated or have not yet been fully activated when the material is first run through.
• FIG. 1 a deep-drawn cup in perspective
• FIG. 2 the area X marked in FIG. 1 in an enlarged representation
• FIG. 3 shows a section through the wall section shown in FIG. 2 along the line III-III
• Figure 6 the section through a four-layer film
• Figure 7 the section through a six-layer film
• Figure 8 the top view of an area of the 6-layer film shown in Figure 7.
• a deep-drawn cup 1 is shown in perspective in FIG.
• This cup 1 consists of two layers, the structure of which can be seen from FIG. 3.
• the inside 7 of the cup wall 6 has isolated elevations 2 which can be attributed to the action of the blowing agent as a foaming agent.
• the outside 6 of the cup wall 5 shows a kind of wood grain, which is achieved in that the transparent areas 4 and the areas made of colored plastic material (color matrix 3) have been pulled apart by the great expansion of the container wall 5 during the deep-drawing process.
• FIG. 2 the area X of the container wall 5 shown in FIG. 1 is shown enlarged.
• the transparent areas 4 and the color matrix 3 can be seen, which have sharp boundaries in the illustration shown here. Such sharp limits are reached if on the one hand a high proportion of blowing agent and / or on the other hand a high temperature is selected in the extruder.
• Figure 3 is a section through a such container wall section shown. It is a co-extruded film that consists of two layers.
• a structured layer 12 which has the color matrix 3 and embedded transparent regions 4, is applied to the inner layer 10. Since the transparent regions 4 extend through the total thickness of the structured layer 12, the inner layer 10 underneath can be seen in the viewing direction A. If the layer 12 has a different color than the inner layer 10, a color structure is obtained in viewing direction A, which is essentially determined by the size of the transparent areas.
• FIG. 4a shows the top view of an extruded film 8, which also consists of two layers.
• the extruded film 8 shows small, circular, sharply delimited transparent areas 4 which are embedded in the color matrix 3.
• the subsequent deep-drawing of an extruded film structured in this way then leads to an appearance as can be seen in FIG. 4b.
• This extruded film shows a line pattern which is characterized by the line-shaped transparent regions 4.
• FIG. 5a shows the top view of an extruded film 8 in which a larger proportion of blowing agent has been added than in the film shown in FIG. 4a. Accordingly, the transparent areas are also larger, with some transparent areas 4 merging into one another. The subsequent deep-drawing of the extruded film 8 leads to the deep-drawn film 9, which is shown in FIG. 5b. In contrast to the figure 4b receives you have a much coarser line structure. Through the choice of the proportion of triturate and / or the extruder temperature it is thus possible to control the fineness of the color structure.
• FIG. 6 shows the section through a 4-layer film.
• a backing material layer 11 is provided on the inner layer 10 and is formed from the production waste.
• This backing material layer 11 carries two structured layers 12 and 13, which are colored differently.
• Transparent areas 4a and 4b are embedded in the structured layers 12 and 13 in the form of continuous islands.
• the transparent areas 4a and 4b are of different sizes and at least partially overlap.
• the colored area 3a of the structured layer 12 lying underneath can be seen through the transparent area 4b.
• FIG. 7 shows a multilayer film in section according to a further embodiment.
• a backing material layer 11, which carries three structured layers 12, 13 and 14, is again provided on an inner layer 10.
• the transparent areas 4a, 4b, 4c of the structured layers 12, 13 and 14 are of different sizes and at least partially overlap.
• On the outer structured layer 14 is still additionally a transparent, antistatic layer 15 is applied.
• FIG. 8 shows the top view of such a six-layer film.
• the areas visible in the direction of the arrows A, B, C and D (see in FIG. 7) are shown in FIG. 8 by different hatching. Because different layers are visible through the overlapping transparent areas, a color pattern is obtained which is characterized by a total of four colors.

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• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Ceramic Engineering (AREA)
• Laminated Bodies (AREA)

Applications Claiming Priority (2)

Publications (1)

Family

ID=6433341

Family Applications (1)

Country Status (4)

Families Citing this family (6)

Citations (10)

Family Cites Families (2)

• 1991
  • 1991-06-06 DE DE4118624A patent/DE4118624C1/de not_active Expired - Fee Related
• 1992
  • 1992-06-04 WO PCT/DE1992/000457 patent/WO1992021505A1/de not_active Application Discontinuation
  • 1992-06-04 AU AU19076/92A patent/AU1907692A/en not_active Abandoned
  • 1992-06-04 EP EP92911430A patent/EP0587661A1/de not_active Withdrawn

Patent Citations (10)

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