CH630939A5 - Process for the manufacture of a plastic sheet material and its use - Google Patents

Abstract

The process makes it possible to produce a plastic sheet material having an appearance similar to cardboard, which can be printed, creased and cut like cardboard to form heat-sealable or gluable containers and other articles. The process is carried out by mixing 5-70 parts by weight of macroparticles of an inorganic material with 95-30 parts by weight of a polyolefin resin selected from polypropylene, sequential polypropylene/ethylene copolymers obtained by first polymerising the propylene and then, before the polymerisation reaction is complete, injecting ethylene into the polymerisation zone in such a way that polymer chains form which become increasingly rich in copolymerised ethylene, random polypropylene/ethylene copolymers and high-density polyethylene, in such a way that a fused mass having a melt index of between 0.55 and 2.2 cm<3>/10 minutes at 230 DEG C under a load of 2.16 kg is produced, and subsequently converting the mass into a sheet by extrusion and/or calendering. It is envisaged that at least one elastomer, at least one soap to reduce the friction between the particles of inorganic material, at least one antioxidant material and at least one swelling material are added to the mixture.

Description

The present invention relates to a process for the manufacture of a sheet material and in particular of a plastic sheet material which offers a wide range of uses for its properties.

The invention also relates to the use of the compound obtained with the process in question to manufacture sheet material.

As is well known at present in many industries, continuous sheet plastic material is widely used, but up to now a plastic sheet material which was of general application and in a large number of fields was not available. In general particular plastic materials are indicated for particular uses and the materials which are indicated for particular use are usually suitable only for other uses.

It is believed that the material offered by the present invention offers a very wide range of uses or uses. For example, it has been found that it is extremely suitable as a substitute for cardboard and paper in general and can also be used to form thin-walled containers such as drinking cups or tubes for food substances and their lids.

In order to provide a plastic sheet material that is suitable for a wide range of uses, we have turned to the introduction of additives designed to obtain a convenient material that could be shaped into a sheet, for example by extrusion and / or calendering and it is believed that, with the present invention, a material of exceptional and new composition is provided, which takes the form of a sheet satisfactorily and the resulting sheet has a wide range of applications.

The process according to the present invention is characterized by what is manufactured by mixing 5-70 parts by weight of an inorganic material in macroparticles and a pigment with 95-30 parts by weight of a mixture consisting of:

a) a polyolefin resin, selected from polypropylene;

b) polypropylene-ethylene sequential copolymers, obtained by polymerizing propylene first and then, before the polymerization reaction is complete, injecting ethylene into the polymerization zone so that polymer chains are produced which become increasingly rich in copolymerized ethylene;

c) polypropylene-ethylene bulk copolymers;

d) high density polyethylene or any mixture thereof;

e) at least one compatible elastomer for sheet materials;

f) at least one soap to reduce the friction between the particles of the inorganic material;

g) at least one antioxidant material;

h) at least one swelling material;

said mixture being first mixed by mechanical processing so as to generate heat and to disperse the inorganic material uniformly throughout the mass, so as to produce a molten mass of uniform consistency, having a melt flow rate between 0.55 and 2, 2 cc / 10 minutes at 230 ° C, under a load of 2.16 kg and subsequently converting the mass into a sheet of thickness between 0.1 and 1.2 mm, by extrusion and / or calendering.

The mechanical processing of the inorganic material and the resin constitutes an important part of the present invention in that it is necessary that the inorganic material can be dispersed very uniformly throughout the resin because otherwise it does not conform satisfactorily in sheets. The head for producing the melt comes essentially from this process, albeit where it is carried out

I

15

20

25

30

35

40

45

50

55

60

65

3

630939

your working by means of, for example, a screw work in a barrel or drum, the latter can be enclosed in electric heating tapes, which can provide part of the heat to the mixture, but, essentially, they are provided to prevent that the heat generated by the mechanical processing escapes from the barrel.

Conventional mixing apparatus such as augers or counter-rotating screws and inter-meshing screws can be used for mixing the resin and inorganic material so as to produce the sheet.

The resin may comprise small quantities of a compatible elastomer.

According to a preferred arrangement of the present invention, the resin is

(c ') a sequential copolymer (as defined below) of propylene having from 10 to 35% by weight (referred to the weight of the copolymer) of ethylene and / or

(a ') a polypropylene compound having a quantity of rubber sufficient to give the compound an impact resistance and flexibility that fall within the field of impact resistance and flexibility presented by the range of sequential copolymers defined in ( b).

It has been discovered that folded containers, other folded and sheared articles according to this preferred feature of the present invention possess most of the favorable properties of high quality cardboard and that a common purchaser would have found it very difficult to make containers that were not cardboard.

Furthermore, the sheet material from which the containers are made is in itself impermeable to water and therefore does not require a waterproofing treatment.

The sheet material will also be arranged flat in the container and veneer manufacturing machinery. These characteristics are obtained without it being necessary in particular to subject the sheet material to an orientation treatment before creasing and folding.

The sheet material according to the present invention preferably has a thickness of at least 0.1 mm, if the folded containers must have properties comparable to those of high quality cardboard and the use of sheet material having a thickness is preferable at least 0.4 mm, which stabs and cuts sharply enough to compete with high quality carton in high speed packaging machinery.

The sheet material can also be satisfactorily thermoformed in a large number of household tubes and cups and their lids.

The sheet material is preferably extruded from a composition comprising a sequential copolymer of propylene and ethylene and / or a mixture of polypropylene and rubber as indicated herein.

By the expression "sequential copolymer" we mean here a particular type of copolymer obtained by first polymerizing propylene and then, before the polymerization reaction is complete, injecting ethylene into the polymerization zone so that, as polymerization proceeds, they are produced polymer chains that become increasingly rich in copolymerized ethylene, randomly distributed among the polymerized propylene. These sequential copolymers in sheet form are softer and more flexible than polypropylene, even mixed with inorganic materials in macroparticles and used for sheets; the sheets have an impact resistance and stiffness comparable to high quality cardboard and, at the same time, the sheets are capable of sufficient orientation to allow a clear folding and creasing as well as thermoforming. These properties are also obtained with sequential copolymers which are materials with a high flow or flow index of the molten mass and therefore are not ultra-high molecular weight materials.

Polypropylene (i.e. propylene homopolymer) can be used to make sheets having an impact resistance and flexibility similar to those of the sheets made with the sequential copolymers described above similar to those of sheets made with the sequential copolymers described above, mixing with a rubber. Examples of rubbers that can be used are polyisobutylene and butyl rubbers and elastomers such as those de-io written on pages 255-258 of the "Chemistry and Industry" of March 16, 1974. The precise quantities of rubber needed to confer impact resistance and the flexibility required of the polypropylene sheets will vary from rubber to rubber and can be determined by tests of impact resistance 15 and ordinary flexibility.

It should preferably be present from 20 to 70% by weight of solid inorganic material, in macroparticles, and it is desirable that this inorganic material have a hardness lower than 5.5 on the Mohs scale. Examples of suitable inorganic materials may include talc, calcium carbonate, dolomite, kaolin or chalk or any combination thereof. The use of an inorganic material, which imparts a soft hand to the sheet, is desirable to facilitate creasing and hinging which, as it seems 25, produce compression in the sheet material. It also appears that inorganic materials of this kind exhibit a desirable effect to the touch of the sheet material. The introduction of soaps and oils into the composition of which the sheet material is formed can greatly improve the production of the material itself. The preferred inorganic material is talc or calcium carbonate; good results have been obtained using both the Chinese talc known as Haichen talc and the calcium carbonate.

Particles of the inorganic material should preferably be able to pass through an ASTM screen of 140 mesh (mesh) and preferably 97% by weight of the particles should be able to pass through the ASTM screen of 325 mesh (ASTM mesh) . Preferred materials should preferably comprise at least 30% by weight of particles 40 having the maximum size between 10 and 18 microns, to favor a good creasing and overturning.

The composition of which the sheet material is formed can also comprise from 1 to 8% by weight of a pigment having a hardness lower than 6.8 on the Mohs scale. 45 The presence of the pigment provides a uniform base or substrate on which to print. The preferred pigment is titanium dioxide. Anatase titanium dioxide has a hardness between 5.5 and 6 on the Mohs scale and has been used successfully. However, rutile titanium dioxide, which has a hardness of 6 to 6.5 causes lower long-term degradation of the sheet material and may be preferable if the sheet material is to be used for the manufacture of hinged containers or other items for which a long life is expected. Both rutile and 55 anatase titanium dioxide pigments should preferably be coated with an alumina amount of up to 5% by weight and silica up to 2% by weight. The pigment can be used together with an optical brightener, such as overseas, in an amount by weight up to P.

60 The composition of which the sheet material is formed, preferably by extrusion, but also by calendering, may possibly contain processing aids, such as soaps, including calcium stearate. The compositions may also contain conventional additives such as stabilizers. 65 The surface of the sheet materials used in the realization of the present invention has a good ability to accommodate printing inks. However, this ability can be further intensified by subjecting the super-

630939

4

fide to one of the oxidation treatments of the type described in the book «Polythene», published by Renfrew and Morgan and published by Iliffe, on pages 542 and 543 of the 2nd edition.

The most convenient of these treatments is the one that uses a corona discharge.

The composition preferably comprises one or more antioxidants and it is suggested to use conventional amounts of inhibited phenolic thioester.

A particular embodiment of the present invention is illustrated by the following example:

a propylene-ethylene sequential copolymer was prepared, comprising 15% by weight of copolymerized ethylene, by polymerization of propylene and subsequent injection of 15% by weight of ethylene in the polymerization zone, before all the propylene was polymerized.

The conditions were chosen so as to produce a copolymer that had a melt flow or flow index of 1.1 cc / 10 minutes.

A thermoformable composition was produced by mechanical mixing, in a mixing machine, of 55.9% by weight of the sequential copolymer, 40% by weight, of a talc in macroparticles, 4% by weight, of a titanium dioxide and 0 1% by weight of calcium stearate, so as to produce an intimate dispersion of the inorganic material in the resin and to heat the mixture in a molten mass of uniform consistency. The talc aro a Haichen talc and 98% by weight of the talc particles could pass through an ASTM 325 screen and 33% by weight of the particles had a maximum size between 10 and 18 microns. Titanium dioxide was an anatase titanium dioxide comprising 1.5% by weight (referred to Ti02) of alumina and 0.7% by weight of silica, in the form of a surface coating on the titanium dioxide particles.

The composition obtained from the mixing machine was extruded into a sheet material having a thickness of 0.8 mm. It was found that the sheet material could be arranged slowly and could be used in the form of cut and creased slices in high-speed machinery used to manufacture cardboard containers folded from veneers. Another characteristic of the material was that it could be cut and creased on conventional cutting and creasing machinery without the use of an adaptation or starting means, thereby facilitating the arrangement of the machinery and reducing the material processing cost. The sheet material is well comparable to high quality cardboard in folding, creasing, scoring, perforating and cutting operations and could be folded to form a container having a crush resistance similar to that of a high quality cardboard container. The sheet material also had good permanent folding properties and could be easily glued. The containers folded and prepared from the sheet material had a pleasant touch sensation and were very receptive to the printing ink so they were almost indistinguishable from a casual observer from folded containers obtained from high quality cardboard.

Furthermore, the material could be thermoformed extremely well in tubes and cups and their lids for domestic use such as those used for the storage of food products such as margarine, butter, jam and so on. Furthermore, it has been found that the material according to the present invention satisfactorily accommodates ballpoint pen markings, solvent-based markings, pencils, machine writing and printing, and the inorganic material imparts a certain surface absorbency to the sheet material. To intensify the receptivity of the material to these markings, it can be subjected to flame treatment or corona discharge treatment.

It is believed that, as an alternative to talc and / or clay in powder form, any other of the following materials or mixtures can be used: clay, calcium carbonate, kaolin (coated, if desired, with stearate), calcium silicate, asbestine, barites, plaster, mica.

In the manufacture of the sheet according to the present invention, this can be obtained in a continuous process, starting from the raw materials, and precisely from resin and an inorganic material in macroparticles, imo or more antioxidants and any other additive required for the purposes of the final use of the leaf, forming a mixture of the raw materials and subsequently bringing the molten mass directly, while it is soft, in a die or in an extrusion nozzle or on calendering rollers, where it is shaped into a sheet. The extrusion die (or the extrusion nozzle) can be attached directly to the mixing device so that a single device performs the two functions, namely that of mixing and that of sheet extrusion.

The process can, however, be carried out in two stages, which are completely separate. Thus, the raw materials indicated above could be initially mixed and the molten mass converted into the form of particles milled by extrusion in the form of strings or strings of material, which are subsequently reduced to the form of solid particles by means of and / or cut into pieces. The raw materials can therefore be mixed by one manufacturer and supplied to another manufacturer for extrusion or calendering in the sheets according to the present invention.

The melt flow rate, determined according to the British Standard 2782 procedure, part 1 / 105C / 1970 on the Davenport standard index determination device, normally measures by weight the material flowing from an orifice in a given period of time under certain conditions of temperature and weight applied, but, since the introduction of the inorganic material into the resin thus significantly affects the specific weight of the mass in comparison with the pure resin, it is better, in the case of the present invention, to obtain the results by determining the volume of the material for a given period of time. In addition, the volume flowing through the orifice is an indication of the purposes of the final use of the leaf, forming a mixture of the raw materials and subsequently bringing the molten mass directly, while it is soft, in a die or in an extrusion nozzle or on calendering rollers, where it is shaped into a sheet. The extrusion die (or the extrusion nozzle) can be attached directly to the mixing device so that a single device performs the two functions, namely that of mixing and that of sheet extrusion.

The process can, however, be carried out in two stages, which are completely separate. Thus, the raw materials indicated above could be initially mixed and the molten mass converted into the form of particles milled by extrusion in the form of strings or strings of material, which are subsequently reduced to the form of solid particles by means of and / or cut into pieces. The raw materials can therefore be mixed by one manufacturer and supplied to another manufacturer for extrusion or calendering in the sheets according to the present invention.

The melt flow rate, determined according to the procedure of British Standard 2782, part 1 / 105C / 1970 on the apparatus for determining the Davenport standard index, normally measures by weight the material flowing from an orifice in a given period of time under certain conditions of temperature and weight applied, but since the introduction of the inorganic material into the resin thus significantly affects the specific weight of the mas5

I

15

20

25

30

35

40

45

50

55

60

65

5

630939

If compared to pure resin, it is better, in the case of the present invention, to obtain the results by determining the volume of the material for a given period of time. In addition, the volume flowing through the orifice is an indication.

Another convenient application for sheet material is the production of playing cards and for the production of these articles it is desirable to ensure that the performance capacity of the material is as high as possible.

The material satisfactorily receives the painting with the use of normal painting techniques which are used for fixing the printing inks on the sheet material or for fixing other impressions on this material.

The sheet material can be satisfactorily thermoformed and can be used for the production of thin-walled containers and their lids, which are produced with a thermoforming process or with an equivalent one. In this process it will be necessary to heat the sheet material. This can be done in conventional ways, but, preferably, it will be done according to one of some patent applications pending the same inventor of the present application,

The material is sufficiently stable and its use gives rise to a product of high quality and good stability.

The sheet material does not suffer a harmful effect from most water-based and solvent-based liquids and, moreover, the material has a remarkably high barrier to humidity. This makes this material extremely suitable for containers that must contain hygroscopic or water-containing products.

If desired, the material can be laminated with another material or coated so as to modify its surface finish.

It should be borne in mind that the filler quantity of the plastic material can be modified at will within the specified range and the material can also include, as explained herein, and to varying degrees, other additives, which may be desirable for the particular use which the material is intended.

The sheet material having the thickness located at the highest end of the field provided can be used to produce binding covers and other more rigid articles, especially articles in which it is desirable to provide a hinge. It is understood that the examples reported in this description are not to be considered in any way as limiting the use of the material itself.

It has been found that the material according to the present invention extrudes extremely satisfactorily and is of high quality. Furthermore, when the material is used to produce articles that are cut out of the material, leaving a scrap skeleton, this scrap can be reused and can be brought back, appropriately crushed in the extrusion press.

In a particularly interesting modification of the present invention, swelling agents as well as an inorganic material in macroparticles are incorporated in the sheet material. The swelling agents are incorporated in most cases, in quantities of secondary importance, as a solid chemical capable of decomposing into gas at a temperature slightly lower than the sheet formation temperature. These chemicals are known as foaming or swelling agents and a typical substance of this kind is p-toluensulfonylsemicarba-zide. The effect of the swelling agent is to considerably reduce the specific weight of the resulting extruded sheet.

In a typical example, a granular mixture, consisting of 60 parts of polypropylene homopolymer, having a melt flow index of 0.55 cc, and 40 parts of finely divided talc, known as Garotalc 132, prepared by dispersing the finely divided talc in polypropylene on a «Buss Ko Kneader» kneader, 5 extrusion of the web material and granulation of the latter, was mixed with 0.4% by weight of p-toluene sulfonyl-semicarbazide. The resulting intimate mixture was extruded on a single screw extruder of 6 "(approx.15.24 cm), having a ratio between length and diameter on the screw of 32: 1, and a sheet material was produced by contact cooling with rollers of the sheet material, delivered by the flat die, fixed to the extruder.

During the extrusion process the temperature of the melt in the extruder drum was increased gradually to a temperature of 220 ° C and the die temperature was maintained at a temperature of 205 ° C. The resulting sheet, with a smooth finish and a specific weight of 0.85 and of adequate mechanical strength, was susceptible of cutting and creasing with processes 20 described in the present description and thermoforming with suitable thermoforming techniques. The specific gravity of a comparable material, produced without the use of a swelling agent was 1.25, so that, with the use of the swelling agents, a considerable increase in the yield 25 of the material was obtained.

The attached schematic drawings will now be mentioned, in which: fig. 1 shows how the compound material is produced;

Fig. 2 shows how shredded containers are produced from the sheet material according to the present invention; Fig. 3 is an enlarged sectional elevation, which illustrates the fundamental difference between the creasing formation using a creasing thread and a semi-cutting knife;

35 fig. 4 is a plan of a veneer of a sheet material according to the present invention, which can be bristled so as to form a packaging container;

Fig. 5 is a plan of a veneer according to fig. 2,

after it has been folded so as to assume a flat flat shape;

Fig. 6 is a view of the flattened shape of fig. 5; Fig. 7 is a terminal view, similar to fig. 6, but which shows how the flattened shape is erected so as to assume the tubular shape;

45 fig. 8 is a perspective view of another veneer of sheet material according to the present invention;

Fig. 9 is a perspective view, which illustrates the sequence of erection operations of the veneer of fig. 8;

Fig. 10 is a perspective view, illustrating the raised container resulting from the veneer of fig. 8;

Fig. 11 is an exploded perspective view of a container of sheet material according to the present invention;

Fig. 12 is a sectional elevation showing how the end covers and the veneer of the container of fig. 11 are 55 fused together; and fig. 13 is a sectional elevation, similar to that of fig. 12, but showing a modified form of the end cover.

In fig. 1 a mixing machine of the conventional form 60 is indicated whose reference number 1 and, as will be seen, it is associated with feed hoppers 2 and 3. The resin, precisely the sequential copolymer resin, is introduced into the mixing machine through the hopper 2, while the inorganic material in macroparticles is introduced into the hopper 3. In the mixing machine the material, which includes any additives, such as antioxidants, coloring material and oils, is mechanically worked in a melt which

630939

6

has the molten mass flow index included in the range specified here and the molten mass is extruded in the form of a plurality of cords, one of which is indicated by the number 4. These extruded cords are cooled or made to cool and are subsequently reduced to particles 5 by means of a grinding apparatus 6. At this stage the mixed particles can be stuffed, as shown with reference number 7, and the mixed particles can subsequently be heated again so as to form a melted mass, in a machine extrusion 10, and extruded in sheet form 12.

Turning now to fig. 2, the extrusion machine is also schematically indicated here with the reference number 10 and the sheet material, which is extruded from it, is indicated with the number 12. In the sheet material 12 a break is indicated between the extrusion machine 10, and a conventional cutting and creasing machine 14, in order to indicate that the sheet material can very well be stored for example in the form of rolls, before going to the machine 14. Indeed, the extrusion can be carried out in a given place or in an establishment and the cutting and creasing can be carried out in another place or in another establishment. On the other hand, it is possible to pass the sheet material 12 directly from the extruder to the cutting and creasing machine 14, assuming that the material is cooled and hardens enough to withstand the cutting and creasing. Furthermore, the material 12 can be more commonly cut into large sheets, which are cut individually and creased as is conventionally done with high quality cardboard.

In any case, the material 12 is illustrated emerging from the machine 14 already cut and creased so as to define the veneer of a container 16, the residual waste of the sheet material is indicated with the number 18. This waste can be reworked by grinding it in the form of particles and returning it to the extruder, to make maximum use of the material.

In the illustrated example, each veneer comprises various rectangular squares connected together by creasing lines formed in the machine 14, and one of the squares is provided with closing end squares 20, another of the squares is provided with a tab for the glue 22. Figure also illustrates the container which can be sterilized by each of the veneers 16, and the erection takes place by means of a conventional method by gluing the tab 22 on the external side of the extreme box to the other side of the veneer. To close the container, the terminal panels 20 are simply folded as indicated with the arrows in the figure and the folds provided in the tabs of these terminal panels serve to keep the latter in the closed position.

It will be understood that machinery 14 can be adapted to produce more complicated veneers or even simpler veneers and thus can provide mobile covers for books or bags, which do not require gluing or the veneers can simply define inserts for insertion in other packaging containers .

Several installations of more specific systems will now be described.

1. Complete polypropylene powder, with stabilizers, etc., and fillers, for example the clay or talc indicated above are taken from bulk storage silos and automatically fed to a high-speed mixer. The intimately mixed ingredients are then fed into a double screw counter-rotating extruder in which the molten polymer and the filler are subjected to high shear action and the resulting homogeneous compound is forced through a standard flat sheet die so as to produce the material in sheet. The extrusion is then passed through a conventional sheet line, assistant to a complex of superimposed polishing rollers, a surface treatment unit, such as a crown discharge unit, an anti-static bath, towing and winding cutter. , ending in a reel winding unit or a shearing and stacking unit for flat sheets.

2. An alternative is to introduce the polypropylene powder with stabilizers, etc., and feed it, with the clay or the charging talc, directly into a mixing unit, such as a "Buss Ko Kneader". The latter should then be provided with a conventional square head extruder, provided with a standard sheet die and with the conventional sheet line apparatus as 15 described in (1).

3. Another alternative could be to replace the standard sheet die indicated in (1) and (2) with a multiple hole die unit facing a cutting unit to produce beads or granules as described in

20 fig. 1. These granules could then be processed through a conventional single screw extruder and a sheet line.

4. Another alternative could be to replace the standard sheet die, provided in (1) and (2) with a strand die, a water bath, a granulator and a

25 drying to produce beads or granules.

The maximum temperature in the mixing and extrusion systems is of the order of 250 ° C.

A P. Ko 200 "Buss Ko Kneader" can produce up to 1,000 kg per hour of 40% polypropylene loaded both in sheet and ball form.

A twin screw extruder with a diameter of 80 mm can produce up to 250 kg per hour of polypropylene loaded at 40% both in the form of a sheet and in the form of spheres.

In the field of sliced and cor-35 donated packaging containers, the material lends itself to the production of unusual and new container structures, several of which have been illustrated in Figures 3 to 13 and will now be described.

Turning now to examine figures 3 to 7, figure 3 shows, in enlarged scale, a section view 40 of the sheet material 110 according to the present invention, which is simultaneously creased by means of a thread for creasing, of structure conventional, and a cutting knife or cutting thread 114. The thread for creasing 112 has a rounded edge, which engages with the sheet 110 45 and therefore tends to compress the sheet against the shape 116, while the thread 114, having an edge of acute cut 118 which engages with the sheet, cuts the sheet and cuts it in the opposite direction to the creasing action of the thread 112. The thread 112 forms a conventional creasing, while the thread 50 114 forms what is known in the specific field as "semitaglio." The half-cut does not need to penetrate half the thickness of sheet 110.

The plastic sheet material 110 is shaped so as to have creases and at least one crease line with 55 semi-cuts to impart certain desired characteristics to the flattened container ("skillet"), as will be explained. It should be noted that if a semi-cut is practiced in the sheet material, it is done due to the need to improve the characteristics of the complete or permanent folding (dead fold) 60 of the sheet and therefore it should be noted that some can be used other arrangements to form the crease instead of the conventional crease, to improve the permanent fold characteristics of the plastic sheet. The term "semi-cut" is intended to protect these 65 equivalent creasing formations.

In figure 4, a simple veneer 120 is shown, which can be reused with a machine for raising containers so as to obtain a flattened container (skillet). The tran

7

630939

ciato is obtained with the plastic material in sheets as shown here and in the figure the creasing lines are indicated by dotted and dot lines while the half-cuts are indicated by double parallel lines. The veneer comprises four panels or panels 122, 124, 126, 128, which are hinged connected to each other along the conventional creasing lines 130, 132 and 134, the panels 122 and 126 are identical also the panels 124 and 128 are identical , but larger than the other two. All the panels or panels are of rectangular section, as illustrated in figure 7. A lateral flap 136 containing glue is hinged on the free edge of the panel 128, the latter is hinged to the panel 128 with the semi-cut creasing line 138.

The ends of the panels from 122 to 128 are provided with conventional tabs and interlocking end closures 140 and 142, as those skilled in the art will understand well. It should be remembered, however, that the flaps and the panels 140 and 142 are hinged connected with the panels 122-128 by means of half-cuts, in order to improve the permanent folding characteristics of these fins and these panels with respect to the main panels from 122 to 128 to which they are connected.

The erection of the veneer takes place by means of conventional erection machinery and in the first stage of the operation the veneer is folded around the creasing line 134 so that the box 128 overlaps the box 126 and partially the box 124. In the next operation the box 122 is folded over the box 124 so as to overlap, in its free edge area, with the strip on which the glue 136 is applied, glue that has been previously applied on the box 122 or on the strip 136 or on both, so that the veneer takes the flattened shape (skillet), as shown in fig. 5.

Since the flattened shape (skillet) has the three conventional creases 130, 132 and 134, it does not lie completely flat unless otherwise forced on it, but rather assumes the position shown in fig. 6 and the creases 134 and 130 slowly recover from the 180 ° bending and this fact together with the natural effect of arching to the creasing 132, causes the flattened shape to be slightly open as illustrated. This slight opening in the flattened condition facilitates its erection to the position shown in fig. 7. In fig. 7 shows two erection elements 144 and 146, of which the element 146 has been inserted in the tubular form while it is in the condition illustrated in fig. 8. To erect the container which is in the shape flattened from the position shown in fig. 8 to that shown in fig. 9, the elements 144 and 146 are moved as indicated by the arrows of fig. 7. With this operation the container folds along the semi-cut creasing line 136, which has good permanent folding characteristics and the sharp edge is maintained there, as illustrated in the position of fig. 7, when the contrasting action of elements 146 and 144 is suspended. In practice, since this edge remains sharp, this has the effect of keeping the entire container in an upright position. If the creasing 136 were a conventional creasing, however, the container would tend to return to the position of Figure 6, which would be undesirable from the point of view of the automatic loading of the container. In a modified arrangement, each of the creasing lines 136 and 132 is defined by a semi-cut.

It will be understood that other forms of flattened container can be produced which accomplish this aspect of the present invention and that the example shown illustrates a particularly simple form of flattened container.

Referring now to figures 8, 9 and 10 and first of all to fig. 8, the veneer 210, as illustrated, can be re-bred in the container illustrated in fig. 10. The veneer is of a synthetic plastic sheet material, as previously exposed, and is suitable not only for cutting and creasing with conventional processes but can also be thermoformed with heating and molding techniques, which are also known conventionally. The veneer comprises a base panel or panel 212, an upper panel 214, a rear panel 216 and an external front or front panel 218, an internal front panel 220 and a thermoformed insert panel 222; these panels are hinged to each other along folding lines 224, 226, 228, 230 and 232. The external front panel 218 is provided with extension tabs for locking 234, while the creasing line 230 has a central slit 236 suitable to receive the tab 234, as will be explained. The rear panel 216 is provided with extension flaps 238, while the internal front panel 220 is provided with shorter extension flaps 240. The molded insert panel 222 is provided with flaps or extension flaps 242 to which hinges are connected. interlocking 244. The creasing lines in the veneer of fig. 8 are indicated by dashed and dot lines while the cutting lines are indicated as normal by solid lines. Finally, the molded insert box 222 is provided with another extension flap 246 which forms an internal rear box in the rised container, as will be evident hereinafter. The veneer 210, regardless of the thermoforming of the panel 222, is cut and creased according to conventional techniques and the panel 222 is molded according to conventional techniques. The cutting and creasing operations can be carried out in succession or simultaneously although in the latter case the cutting and creasing machine should be modified so as to simultaneously carry out the thermoforming or the thermoforming machine should be adapted so as to carry out an operation of cutting and creasing.

The creases formed in the veneer can be obtained by any conventional means, for example with creasing fillets or with means that provide semi-cuts or cup-shaped cuts.

To erect the veneer shown in fig. 8 so as to obtain the container shown in fig. 10, the veneer is firstly folded around the creasing line 236 as indicated by the arrow 246 in fig. 8. Furthermore, the box 222 is folded inwardly around the creasing line 232 until it reaches the position shown in fig. 9. The boxes 214, 216 and 218 are folded in a vertical plane around the creasing line 228 and this succession of operations causes the veneer to reach the condition represented in fig. 9.

To complete the container, the flaps 238 and 240 at the ends of the container, as shown in fig. 9, are folded inward and the ends are closed with the tabs 242; and the inward folding tabs or flaps 244 are folded under the tabs 238 and 240. Finally, the container is closed by folding the panels 218 and 214 around the creasing line 226 and inserting the extension tab for fixing 134 in the slot fixing 236. This erection can be carried out either by hand or by machine, but in any case it is a packaging container having a molded insert, which forms an integral part of the original veneer, which represents a significant difference compared to known packaging containers, in what these known containers are normally provided with a separate insert, and is obtained with the production of the sheet material according to the present invention.

It should be borne in mind that the items to be kept in the compartments printed in box 222 should be included5

10

15

20

25

30

35

40

45

50

55

60

65

630 939

8

rituals in these compartments before the final closure of the container.

It should be kept in mind that this aspect of the present invention has wide application, as imposed by the product to be retained in the container. For example, the printed parts could be designed to contain a specific article, such as an Easter egg or a decorative bottle, in a specific position with respect to the external dimensions of the packaging, so that the article was not only effectively held by the parties. printed, but also could be visible through the openings made in the walls of the container.

In other embodiments where it is necessary to form fixed seams, i.e. equivalent to seams glued in the cardboard containers, the plastic material can be heat welded or sealed. Of course there is no reason why these joints cannot be provided by means of adhesive parts of the veneer itself, but the fundamental use of a plastic material according to the present invention offers the further possibility of sealing and hot welding.

Referring now to figures 11 to 13, in fig. 11 shows a container for packaging which includes a part which constitutes the body 310 and two end caps or covers 312 and 314. The latter are of identical structure. The body 310 is a cut and creased veneer of plastic material according to the present invention. The body is generally of square section and has a joint 316 that runs longitudinally on the body; this joint is made up of a tongue or an overlapping flap obtained in the cut and creasing of the veneer. The body 310, before the connection of the covers 310 and 312, can be collapsed in the flattened condition for transport.

Each of the end covers 314 and 312 is made of the same material as the body 310, but is molded, in this case thermoformed.

If you use the container shown in fig. 11, the caps or end covers 314 and 312 and the body 310 can be transported as separate articles. The person who will fill the container, for example, with a liquid medium, will erect the body 310 in the condition illustrated in fig. 11, will insert one of the covers 310 and 312 into the convenient end of the body 310, fill the body and then insert the other cover 312 and 314 to the other end of the body, the covers are sealed liquid-tight in position to seal completely the container.

The container can be provided with an easy-to-open device either in the body 310 or in one of its end covers 312 and 314 or in both.

When attaching each cap or lid 312 or 314

to the body 310, the surfaces of the lid and of the body which are brought into contact may initially be softened with jets of hot air and then the softened surfaces which make contact are compressed together in order to melt together the plastic material of the lid and of the body.

Fig. 12 illustrates how the cover is inserted into the body 310 and also illustrates a pair of pressure molds 318 and 320, which serve to compress together the area of the flange of the cover 314 and the overlapping wall parts of the body 310.

Fig. 13 shows a modified form of the end cover 314 which is provided with an additional flange part 314B and located outside the wall parts of the body 15 when the cover is inserted on the body as shown in fig. 13. In this arrangement, the internal surface of the additional flange 314B and the external surface of the wall part 310 on which this flange 314B is superimposed are softened before they are 20 tablets together as indicated in fig. 12, using molds 318 and 320. Instead of melting the surfaces of the covers and the body with heat, it is possible to melt them together using a thermal seal or thermal weld or an ultrasonic or high frequency weld.

25 The embodiment of the present illustrated invention is suitable, for example, for containing liquids. It has the advantage of taking up relatively little space during transport and the plastic material does not have the disadvantage of the "wick" effect of the raw edge, what happens in equivalent cardboard containers.

It will be understood that this aspect of the present invention can be applied to containers with a structure other than that illustrated, since the illustrated shape is an extremely simple example. In another embodiment, only one of the caps or lids 312 and 314 can be used and the other end of the body can be closed tightly forming thread creases and heat sealing the parts of the body wall which they are brought together by bending the body around the fillets. 40 The present invention also provides the process for manufacturing containers and other articles folded or sheared for them, according to the present invention, using conventional machinery for the manufacture of containers, and other articles or shears for them in full cardboard. 45 gato, with or without a starting device.

It is also possible, as illustrated in fig. 2, to produce thermoformed containers, such as tubes and cups, as indicated in the drawing, away from sheet 12. Conventional thermoforming methods can be used.

v

4 drawings sheets

Claims (10)

630939 1. Process for the manufacture of a sheet material characterized in that it is manufactured by mixing 5-70 parts by weight of a solid inorganic material in macroparticles and a cori pigment 95-30 parts by weight of a mixture formed by: a) a polyolefin resin, selected from polypropylene; b) polypropylene-ethylene sequential copolymers, obtained by polymerizing propylene first and then, before the polymerization reaction is complete, injecting ethylene into the polymerization zone so that polymer chains are produced which become increasingly rich in copolymerized ethylene; c) polypropylene-ethylene bulk copolymers; d) high density polyethylene or any mixture thereof; e) at least one compatible elastomer for sheet materials; f) at least one soap to reduce the friction between the particles of the inorganic material; g) at least one antioxidant material; h) at least one swelling material; said mixture being first mixed by mechanical processing so as to generate heat and to disperse the inorganic material uniformly throughout the mass, so as to produce a molten mass of uniform consistency, having a melt flow rate between 0.55 and 2, 2 cc / 10 minutes at 230 ° C, under a load of 2.16 kg and subsequently converting the mass into a sheet of thickness between 0.1 and 1.2 mm, by extrusion and / or calendering. 2. Sheet material prepared by the method according to claim 1. 2 3. Use of the sheet material obtained by the process according to claim 1 to manufacture household and industrial objects. 4. Process according to claim 1, characterized in that said mixture comprises: (c ') a propylene sequential copolymer containing from 10 to 35% by weight, based on the weight of the copolymer, of ethylene and / or: (a ') a polypropylene compound having a quantity of rubber sufficient to give the compound an impact resistance and flexibility, which fall within the field of impact resistance and flexibility possessed by the range of sequential copolymers defined in (b ). 5. Process according to claim 4, characterized in that the resin consists of the above indicated mixture of polypropylene and the rubber is selected from polyisobutylene butyl rubber and ethylene-propylene elastomers. 6. Process according to claim 1, characterized in that the solid inorganic material in macro-particles has a hardness lower than 5.5 on the Mohs scale. 7. Process according to claim 6, characterized in that the solid inorganic material in macroparticles can pass through a 140 mesh screen (ASTM mesh). 8. Process according to claim 6, characterized in that 97% by weight of the particles of inorganic material can pass through a 325 mesh screen (ASTM mesh). 9. Process according to claim 6, characterized in that at least 30% by weight of the particles of the inorganic material has a maximum size between 10 and 18 microns. 10. Process according to claim 1, characterized in that the inorganic material is free of fibrous components.