DE2049471A1 - Process for the production of laminates - Google Patents

Description

concerning:

"Process for the production of laminates."

The invention relates to laminates with a layer of foamed plastics, such as foamed polystyrene, and their production.

Polymers of aromatic vinyl compounds, such as polystyrene, can be converted into foams in various ways will. If you want to shape a product with a certain shape, you usually use polymer particles that contain a volatile propellant, allows water vapor to act on these particles to cause an expansion (known as "pre-expansion") to effect and then melts the expanded particles in a heated mold of a certain shape. Should on the other hand, make continuous fabric sheets or panels

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are placed, it would of course be inexpedient to achieve this through individual deformation operations and There are therefore currently for the continuous production of such foamed webs or plates two basic; In addition, various techniques were used.

Immediately gassing in the extruder causes non-toughened polymer, e.g. crystalline polystyrene, to come together with suitable core-forming additives in a specially designed extruder, in which the charge

"is first gelled. In the gelled, not toughened A volatile blowing agent is injected into the polymer under high pressure and intensively homogenized with it; the resulting The mixture of polymer and blowing agent is pressed out through a suitable nozzle, in general as a large one Tube which is inflated by internal pressure, compressed by rollers and slit open in two tracks; it can also be pulled over a stretching mandrel. So that the fleeting If blowing agent can be injected into the gelled polymer at high pressure, special gassing is required in the extruder Use special types of modified extruders, which makes high investments inevitable. on the other hand

), this method enables high outputs for one relatively cheap raw material of non-toughened polymer and blowing agent.

Another process for the continuous production of foamed polymer webs uses polymer particles into which a blowing agent is incorporated, which is volatilized (or activated) under the extrusion conditions . The expandable particles are fed into a conventional extruder, which they leave as a wide, inflated tube, as in the other process. This verse

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Driving does not require the high investment costs like direct gassing in the extruder, but on the other hand it is Expenditure for the expandable particles is higher than with the separate use of non-toughened polymer and propellants.

In either of the above-described methods of making extruded, peeled polymeric webs, inevitably falls a certain amount of waste, for example during extrusion, slitting or trimming of the extruded tube or in the deformation of the resulting webs in a vacuum. With direct gassing in Extruder it is relatively easy to reuse this waste, since it is compressed and not toughened Starting polmer can be added for further processing can. The fact that the propellant has been used up in the waste does not matter, since in this process the The starting polymer does not have to contain any blowing agent, since this is introduced into the extruder itself under pressure.

It is different with the waste that is obtained when using expandable particles: the waste pieces can are not added to the expandable starting particles in this Pail, otherwise there will not be enough active propellant were. The result would be that the mixture would insufficiently "open" during the extrusion process, which would be undesirable Defects in the foam sheet would lead. In view of the relatively large amount of waste it poses its recovery poses a problem for the manufacturer and this is undoubtedly a disadvantage of the process in which expandable particles are compressed.

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Purely many purposes for which foam sheets are used it turned out to be useful to cover the foam sheet with a thin layer of toughened (high pressure-resistant) polymer. As is well known, toughened polymer is not expanded and contains a certain proportion of elastomer components, such as rubber, so that this material has high impact and compressive strength (or notched impact strength) having. A laminate composed in this way has valuable damping and insulating properties of polymer foam, with the tough and flexible top layer of impact-resistant polymer reducing the problems which could otherwise occur due to the spräden character of the foam. Such a compound Material is particularly useful in the packaging industry.

It has now been found that the scrap pieces used in the manufacture of the above-described laminates or their subsequent processing can be reused by turning them into a toughened one Incorporated polymer of an aromatic vinyl compound, wherein the rubber content is adjusted so that the final mixture has the desired printing properties.

The process according to the invention for the production of laminates which enables the waste to be reused by joining a layer of foamed polymer of an aromatic vinyl compound with one or more Layers of toughened polymer of an aromatic vinyl compound is therefore characterized in that the The layers of toughened polymer used are formed from a mixture of freshly added tough made) polymer and laminate waste from processing the laminate, the elastomer content

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of the freshly fed polymer is adjusted so that the formed after mixing with the waste pieces Web made of toughened polymer has the desired printing and impact properties.

The most important polymers of aromatic vinyl compounds are currently styrene polymers and copolymers, e.g. polystyrene or copolymers made from styrene and acrylonitrile or from styrene, acrylonitrile and butadiene (ABS). When polystyrene is mentioned in summary below, however, polymers and copolymers are also made by others aromatic vinyl monomers meant.

Although it is basically irrelevant by which method the polymer foams off, the method according to the invention is of course of particular value if this component of the laminate is formed by extruding expandable (ie gas-containing) particles, because in this area the reuse of Pieces of waste are particularly important. The web of expandable polymer is therefore preferably formed by extruding particles of a polymer of an aromatic vinyl compound which contain a blowing agent which is volatilized or activated under the extrusion conditions. Particularly suitable expandable particles are beads made of polystyrene which contain about 5 1 ° pentane and which have been shaken or stirred with smaller amounts of white oil, citric acid and sodium carbonate; these beads are preferably extruded through a twin screw extruder (example: the RC 100 model, available from GKN Windsor). If necessary, the foam web can also be formed in such a way that the particles are expanded in a two-stage process and shaped into a foam block, from which thin "veneers" are then peeled off.

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The two webs of expanded polymer and toughened polymer, for example polystyrene, can be combined in any desired way to form a laminate, the following procedure being particularly useful: The mixture of toughened starting polystyrene and scrap laminate is placed in an open Coating device (such as the roller coating machine from the ¹¹ Z always "type, available from Spooner Edmeston), from which the mixture is applied as a coating to a preformed sheet of polystyrene foam. However, other methods can also be used, for example by pressing the toughened polystyrene sheet directly from the press onto the expanded sheet, or vice versa.

Any suitable toughened polymer of a vinyl aromatic compound can be used as the toughened starting polymer can be used provided that its impact strength is higher than that which the toughened component of the laminate should have at the end. This can be achieved, for example, by using a material with increased Rubber content used as the admixture of laminate waste the rubber content diluted to the usual proportion, so that the corresponding strength properties can be achieved. Instead of this, a toughened polymer of a vinyl aromatic compound can also (preferably) be used be used, which contains the usual rubber content, but a higher rubber value (rubber utilization) Has. Are suitable as elastomer components for obtaining the toughened polymeric aromatic vinyl compound including natural and synthetic rubber, polybutadiene and synthetic rubbers made from styrene and butadiene.

That in the British patent application is particularly suitable as a starting material for the non-foamed layer

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16106/69 described toughened "polystyrene with a high proportion of lubricant, which is obtained by polymerizing styrene in the presence of the usual amount of rubber (eg 6 to 7 wt .- $) plus at least 10 wt .- ^ lubricant. This polymer has a substantial higher notched impact strength than the usual materials with the same rubber content. Due to its high impact strength and strength, this material with a high lubricant content can be "diluted" with up to 50 i> (preferably with 35 i °) "crystalline" polystyrene, whereby its impact strength or Strength still remains within acceptable limits A toughened starting polystyrene particularly suitable in accordance with the invention for the non-foamed layer is therefore a product made by the process laid down in the aforementioned British patent application, which process consists in making an aromatic vinyl compound in the presence of an elastomer polymerized so that the containing polymers an elastomeric disperse phase and a continuous phase from the polymer of the aromatic vinyl compound in question, at least 10 wt .- $ of an additive which is an organic substance of low volatility and is preferably compatible with the disperse phase, are present in the polymerization mixture before the gelation has ended. The additive does not consist of 13% by weight or more of a petroleum jelly or a lubricant which is composed of petroleum jelly and up to 40% by weight of a mineral oil.

First, this starting material is diluted with an appropriate amount of "crystalline" polystyrene, however As the work progresses, the crystalline polystyrene is gradually replaced by waste laminate until Finally, the toughened polystyrene sheet is formed entirely from a mixture of the starting material with waste will. Of course, the rubber additive does not have to be added to this

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2043471.

diluted starting material must be carefully matched to the average amount of waste generated in the overall operation. Then all of the waste can be diluted of the starting material and there is then no additional crystalline polystyrene as a diluent necessary to achieve the desired strength properties in the end product. Eb is, however, to be expected that the amount of waste fluctuates and a temporary addition of crystalline polystyrene for dilution may occasionally occur become necessary, but the working conditions should be chosen so that this is as limited as possible. In general, it can be said that it is advisable to choose the rubber additive in the starting material so that it is 20-50% Dilution by "crystalline" polystyrene is necessary in order to give the laminate component the desired pestibility properties want to lend.

Up to now, laminates made of expanded polystyrene and toughened polystyrene have been used directly under heat or in a vacuum to the desired three-dimensional shape including corresponding reinforcing ribs, cams, etc. shaped. However, since such objects are not collapsible, they take up one when they are empty very large space and therefore collapsible cardboard containers are often preferred if space is a concern. Such cardboard boxes or crates are known to be obtained so that you bend the flat, folded blank along the split or crease lines attached to it and noting the sides; When these containers are not in use, they can be collapsed and flattened Porm to be stored. It is a special feature that is decisive for their use in the packaging industry of the laminates according to the invention that they can be heated and / or different pressures as flat-lying porms

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that can form not only reinforcing elements, such as reinforcing ribs but also split or crease lines along which the blank can be folded into the desired packaging shape. The laminates according to the invention from expanded polymer of an aromatic Vinyl compound and toughened polymer of an aromatic vinyl compound can be used for the production of flat packaging blanks by they are brought into a shape with the use of pressure or vacuum and, if necessary, heat at the same time, which also have reinforcing elements and has fold lines. From the raw pieces, which are trimmed if necessary, Then produce packaging by folding the blank along the crease lines and thereby inserting the individual parts brings the desired relative position to each other, in which they are then determined. This method is particularly suitable for the production of, for example, boxes for agricultural products, which are then simply produced can be that one on a rectangular sheet of laminate, for example by the application of heat or of Vacuum forms the corresponding impressions, cuts out the corners of the resulting blank, erects the four sides and fix the edges so that you get a corresponding box.

The examples serve to explain the invention in more detail: Example 1

One starting polystyrene with $ 6.9 rubber and one Izod impact strength of 0.25 mkg / 25.4 mm notch (manufactured according to British patent application 16106/69, im Trade under the protected name "CARINEX" SI 69) was sold with 35 G-ew .- # "crystalline" polystyrene beads

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mixed and fed into a "Zimmer" type roll sizing machine. Simultaneously, a web was made of expanded polystyrene by gave (100 Windsor RC) polystyrene beads in a twin-screw extruder, which contained 5 parts by weight of pentane and 56 in advance with 0.05 ° Ί white oil, 0.4 $ citric acid, and 0, 5 $ sodium bicarbonate had been impregnated - whereupon these beads were ^{extruded at about 130-15O 0} C through a compression nozzle, the resulting wide tube made of expanded polystyrene at a blow-up ratio of 2.8

. peeled off at a speed of 4 m / min and slit the tube, * so that an open path was created.

The roll coating machine used above was then used to apply the mixture of "Carinex" SI 69 and Kristallinem To apply polystyrene to the sheet of expanded polystyrene at a speed of 5 m / min, whereupon the resulting laminate was fed to a suitable trimming device. Got there at a speed of 75 g / min of waste produced, which was then used to produce a corresponding amount of "crystalline" Replace polystyrene. In a short time, continuous work was achieved, with 244 g of "Carinex" SI 69, 75 g recycled waste and 56 g of "crystalline" polystyrene per minute were fed to the coating machine in which every minute 5 m of a 60 cm wide polystyrene sheet was provided with a 50 cm wide coating. The one in the trimmer The waste produced (75 g / min) was fed back into the coating machine.

Part of the laminate prepared as above was used Formed in the heat into a packaging blank, which is a closed rectangle of fold lines, together with ■ reinforcing ribs as well as a protuberance within the rectangle made of Balt lines. At each corner of the blank between the fold lines and the piece edge were square pieces

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punched out, so that by folding the trimmed raw piece-and- Attaching the corner edges to the other sides got a usable packing box.

Example 2

An NRM extruder with a diameter of 89 mm and a screw length of 20 diameters, which was equipped with a 610 mm wide flat die for extruding webs, was used to extrude 0.125 mm thick webs of toughened polystyrene, the starting material being 65 parts Shell »Carinex» SI 69 and 35 ropes consisted of »crystalline» polystyrene in granular form. The temperature of the extruder was in the feed zone 110 ⁰ O and to the nozzle 170 ⁰ C.

The extruded polymer sheet was polished between the top pair of a vertically arranged group of three Chill rolls held at 75-95 ° C and then passed through a pair of rubber take-off rolls. When the pressing process Once started, a sheet of expanded material was created in the gap between the hot melt and the upper roller Polystyrene introduced so that both lanes were combined.

The laminate produced in this way consisted of equal parts by weight of the mixture of 'Oarinex "SI 69 and" crystalline " Polystyrene on the one hand and polystyrene foam on the other. The laminate was then cut to size and the waste is crushed in a granulator (USI model 1216). The shredded waste consisted of about 50 parts of unmodified polystyrene (from the polystyrene foam), 17.5 parts of unmodified polystyrene (originally supplied as "crystalline" grains) and 32.5 Share "Carinex" SI 69.

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Example 5

100 parts of the crushed waste obtained according to Example 2 were mixed with 100 parts of "Carinex" SI 69 and through a ventilated extruder (Buss-Ko-Kneader PR 100) Squeezed, pie strands of degassed extrudate were cut into small particles, the composition of which is as follows was:

67.5 parts of modified polystyrene from the polystyrene

gohaumstoffbahn and the laminate; 62.5 parts of "Carinex" SI 69 from the laminate; w 100 parts of "Carinex" SI 69 added to the mixture.

It binds 66.25 parts of "Cerinex" SI 69 to 53.75 parts "Crystalline" polystyrene was present, i.e. approximately the original proportions, pas go reprocessed granules then placed in an 89 mm NRIYK extruder and as above used to coat a fresh polystyrene foam sheet. Pas ratio of "Carinex" SI 69 and crushed Laminate waste can of course either be on the degassing stage or adjusted accordingly at the lamination stage.

Example 4
>

Crushed laminate waste obtained according to Example 2 were degassed on their own in the Buss Ko-Kneader PR 100; the resulting granules consisted of?

67.5 parts of unmodified polystyrene aye of the expanded

Polystyrene sheet and the laminate; 62.5 parts of "Oarinex" SI 69 plus the laminate.

The granulate was then mixed with 100 parts of "Carinex" SI 69 and the mixture was fed to the 89 mm NRM extruder for coating freshly prepared polystyrene foam. _ ^ ^

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Example 5 .

100 parts "Carinex" SI 69 and 100 parts crushed Laminate waste, produced according to Example 2, was immediately fed to the 89 mm KRM extruder. Since the crushed If waste was to be degassed only in the lamination stage, a special ventilated screw was used Retarder used.

claims 8632

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Claims (5)

Claims 1J method of manufacturing laminates by Connect a layer of foamed polymer one aromatic vinyl compound with one or more layers of toughened polymer of an aromatic vinyl compound, characterized in that the used Layers of toughened polymer are formed from a mixture of freshly added toughened Polymer and laminate waste from processing the laminate, the elastomer content of the fresh supplied polymer is adjusted so that the web formed after mixing with the waste pieces made of toughened polymer has the desired pressure and impact properties. 2. The method according to claim 1, characterized in that the polymer is an aromatic Vinyl compound is polystyrene. 3. The method according to claim 1 or 2, characterized in that the layer of foamed Polymer is formed by extruding e; in blowing agent, preferably pentane, which evaporates during extrusion or activated, containing polymer particles. - 15 - 109817/1863 4. The method according to claim 1, 2 or 3, characterized in that the toughened polymer as an elastomer natural or synthetic rubber, polybutadiene, acrylonitrile-butadiene-styrene rubber or Contains styrene-butadiene rubber. 5. The method according to any one of the preceding claims, characterized in that the toughened Polymer contains a lubricant additive. 109817/1863