DE1902150A1 - Process for the production of foam moldings from olefin polymers - Google Patents

Description

Badische Anilin- & Soda-B'abriK

Our reference: O.Z, 25 972 Ks / zm 67ΟΟ Ludwigshafen, I5.I.1969

Process for the production of foam moldings from olefin polymers

The invention relates to a method for producing foam -Shaped bodies, in which plates or webs made of foam-shaped, Thermoplastics in their thermoplastic state deformed will.

Served in the production of foamed moldings from individual particles As a rule, the welding or sintering of expandable or foamed, but still expandable individual particles in molds under the influence of heat. This procedure will especially in the production of polystyrene foam moldings technically used from individual particles. Because the foamed Additionally foam polystyrene particles in molds to a high degree, weld them to one another without the additional external influence of counter-pressure, reducing the inner space of the mold.

This method of producing molded articles from individual particles is equally impracticable for olefin polymers, because the expandability of the already foamed individual particles Olefin polymer is too small when heated in molds, so that without external application of additional pressure under Ysr = By reducing the volume of the mold, no cavity-free and homogeneous foam test-off moldings can be produced.

Polystyrene foams, which are made from foamed particles can not be verforsrö in the thermoplastic state, since the expanded particles do not sufficiently firmly to one another under these conditions adhere and "Dahax" kömmt ae _s not sufficiently stretchable are that such foam Platt © a - - & MB Polystyrene during thermoplastic deformation cracked iferd © n ■ s © rr $ 4.3se2io Im Q®isßnaa, tz da & u can 8ohaumstoff © _# di © unruh trudiereii made of foamed "polystyrene or % 701/68 ■

are manufactured, are thermoplastically deformed,

Foam-like individual particles made from uncrosslinked ethylene polymers cannot be welded to form sheets in the thermoplastic sector because the volume is reduced too much. It it is therefore also not possible to produce moldings on this basis.

The present invention was based on the object of producing moldings from sheets or webs of foamed olefin polymer particles. ■ '

The invention is a process for the production of Foam moldings by heating plates or webs from foamed olefin polymers to temperatures above the softening point, deforming in the thermoplastic state and cooling the moldings, whereby plates or webs of welded, foam-shaped. Particles of olefin polymers "used, which contain cross-linked parts.

Surprisingly, the process according to the invention gives Foam moldings in which the individual particles are firmly attached to one another are sintered. The individual particles are so solid welded together so that even in the event of elongation at break, it is not the sintered areas that tear, but rather the particles themselves.

The plates or sheets have a thickness which is preferably between 2 to 100 mm. They are made of foam-like particles ^ which contain cross-linked parts. The manufacture of panels from foamed individual particles has been described, for example, in French patent specification 1,522,651. This process involves heating. foamed particles in closed molds and pressed them in the thermoplastic state by 5 to 60 percent by weight of their original Rubble volume together. The individual particles weld together together into plates.

In the context of the invention, flexible polymers are particularly intended to crystalline OleCLnpolymerlsate are understood, whose X-ray - ";" -. ·

at 85 ⁰ C is over 25 % . Suitable for the procedure

homopolymers of ethylene, propylene and butene or copolymers of these monomers. Above all, polyethylene, especially high-pressure polyethylene and copolymers of ethylene with ethylenically unsaturated monomers *, for example with C ₁ - to Cg-alkyl esters of acrylic or methacrylic acid, of which the butyl esters are used in particular, are particularly suitable. It is also possible to process chlorinated olefin polymers with a chlorine content of 12 to% by weight to give foam moldings by the process according to the invention. If polymers with a higher chlorine content are used, the advantage of the process does not occur or only partially. Chlorinated ethylene polymers should generally have molecular weights between 20,000 and 200,000 and a softening point between 80 and H0 ° C. It is preferred to use polymers made from chlorinated high-pressure polyethylene.

Foam-like olefin polymers with predominantly closed-cell Structure are produced according to the usual procedures.

Foam-like particles are used for the inventive method used, the apparent weight of which is preferably between 20 and 50 g / l and whose diameter is between 5 and 30 cm. You fall in the above-described foaming process either directly in this Size or are reduced by crushing during the foaming process resulting moldings!

The particles of the mustard-shaped olefin polymers can be obtained on the olefin polymer, contain high to 100 percent by weight additives, such as flame detergent, dyes, lubricants, fillers or polymers such as polyisobutylene. One-piece fibrous materials have proven particularly useful as fillers. Wood fibers or thermoplastic fibers are preferably used Plastics. Sometimes it is also advantageous to use the foam form! gene Particles In a mixture with coarse-grained or fibrous fillers or reinforcing materials to process. Coarse-meshed fabrics or grids, e.g. made of thermoplastics, can also be used as reinforcement inserts Work into the foam panels. You can also, for example, sheets laminated with metal plates on both sides to form moldings to process.

In order to be able to carry out the method according to the invention successfully,

one must start from such plates or webs, in which foamed olefin polymer particles are welded together, Contains crosslinked components By crosslinked components are understood the parts by weight of polymers which are insoluble in organic solvents at temperatures above the crystallinity melting point. The content of cross-linked units will be determined for example by heating the particles in toluene at temperatures of 100 ⁰ C, filtration and drying of the insoluble polymer. .

The foam-like particles containing crosslinked components can be used obtained by various methods. Among these has become a working method in which the foam-shaped, closed-cell particles are treated with high-energy rays has proven particularly successful will. For example, X-rays or electron beams can be allowed to act on the particles. In a way of working for manufacturing of the particles, which is particularly suitable, the small-particle olefin polymers are treated with electron beams, their dose is between 1 and 60 Mrad.

The foam-like particles can also be crosslinked with compounds which break down into radicals when the particles are foamed. The comminution products of, for example, are also suitable Moldings made from olefin polymers obtained by foaming with azodiisobutyronitrile.

Foam-shaped particles are used for the production of the panels, whose content of crosslinked components is 5 to 80 percent by weight, preferably 20 to 70 percent by weight.

According to the method according to the invention, foam sheets or -Plates, which are made of cross-linked, welded, foam-shaped particles consist by heating with infrared rays, hot air, steam or also heated in a high-frequency field to a temperature above the crystallite melting point, preferably to temperatures from 120 to 180 ° C.

The heated plate section can then be placed on a cold ^{metal mold or a metal mold that is heated up to a maximum of 50 °} C. and is open at the top. · By approximating a suitable counter-shape, the foam

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thermoplastically deformed. After 3 ms 10 minutes one takes out Foam molded body that precisely reproduces the dimensions of the shape. In this way, 50 to 100 moldings can be made in a multiple mold Dimensions are made. According to the invention The process also succeeds in producing moldings of the most varied of shapes with a very variable wall thickness from 1 to 20 mm.

The thermoplastic deformation of the foam sheets made from cross-linked, welded, foam-like particles can also be very advantageous with the help of vacuum deep-drawing in the for this Common devices can be achieved. This process makes it possible to produce molded foam bodies in one operation and at the same time films made of polyethylene, polypropylene, polystyrene, polyvinyl chloride, polyamides or polymethacrylates apply to the molded body. There is no adhesive necessary because of the highly cross-linked foams made from olefin polymers even at short notice to 150 to. can be heated to l80 ° C, without shrinking. So you can, for example, foam sections, which have a gel content of 60 percent by weight, Heat to 160 ° C for 10 minutes and then thermoform.

The method thus makes it possible, in a relatively simple way, by yourself Complicated moldings of the most varied of shapes to be produced without having to use individual molds for each molding got to. On the contrary, it is possible to produce a large number of shaped bodies at once in one operation. The moldings can in the usual way additionally coated, printed, with characters, provided or combined with other plastics.

The technical application of the molded foams can be very diverse. The use of a shipping container should be emphasized or as an insert in containers of a different structure, e.g. in those made of cardboard, metal or plastics. Here you can the foam inserts are preferably shaped so that the The goods to be shipped are fully seated. However, molded foam parts can also be used

be advantageous that have the shape of corner pieces or cylindrical Shaped bodies that protect the goods from being shaken or damaged during transport Protect adequately in the event of high impact loads. Moldings

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Greater wall thickness can be used as a covering material on its own serve for shipping goods.

The foams produced with the inventive method according to "be used as Inneniage (core layer) between different types of materials, for example between two metal surfaces, or between plastic and metal surfaces. One can obtain the foam with materials strength bonds when heating the material above 130 ⁰ C. and then brought into contact with the foams which have been heated to temperatures above their crystallite melting point.

The molded foams can also be used to make all kinds of objects for everyday use, e.g. plant containers, inserts for clothing and furniture, as it has been done before Foam plastics or lighter memory materials' is handled. In the deep-drawing process, hat inlays can also be used, Make model busts, decorative bodies of various shapes. Especially when using molded foams with a compact cover, e.g. made of a hard plastic film achieve extraordinary effects. Moldings with colored outer layers are used, for example, as dashboards in automotive engineering.

In the deep-drawing process, large shaped objects can also be cut into gain in one operation, e.g. floats, insoles in life jackets, Profile body. Such foamed profile bodies can also be used with advantage in insulation technology.

The process according to the invention gives moldings which, compared to the known foam moldings, have a significantly improved resistance to solvents and resistance to aggressive chemicals such as sulfuric acid, soda oil? . , e formalin, distinguished "Due to a higher gel content, the foam molded article having an improved long-term heat resistance, the upper temperature limit is 130 ⁰ C at a gel fraction of at 8O weight percent.

The percentages given in the examples are percentages by weight.

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Example I ■

A 5 mm thick foam sheet is produced from cross-linked, foamed polyethylene (softening range 105-110 ⁰ C), the diameter of which is 12 mm and the bulk density of 12.5 g / l, by placing the particles in a closed mold under pressure in thermoplastic State to be sintered. The foam-shaped particles contain 50 percent by weight of crosslinked components. The plate produced in this way is ^{heated to 130 °} C. by the action of infrared rays and placed on a metal mold with the dimensions 15 × 11 × 2 cm, open at the top. The mold is not heated. Then there is a counter-form. which can be fitted into the recess at a distance of 4.5 mm. After 5 minutes, a shaped body is removed that has the dimensions of the depression and looks like a box-shaped shipping container.

Example 2

From a sehaumförmigen, predominantly closed copolymer of 8j5% ethylene and YJ% acrylic acid tert-butyl ester, which is present in the form of spherical particles of 15 mm in diameter and has a bulk density of 16 g / l, after the irradiation in the electron accelerator with 60 Mrad, with a gel content of 84 fo in the copolyraerisate, a homogeneous foam sheet 15 mm thick is produced by welding the particles above the softening point and compressing them by 50 % of the original bulk volume.

This plate is clamped in a conventional device for deep drawing and with infrared radiation to a temperature above of the softening point, namely to ~ Ί3> 5 ° 0. Then it will be a multiple form to which vacuum is applied from below to the heated. Foam sheet approximated so that the foam sheet adapts to the contours of the multiple shape. From this, the surface is cooled with an air fan and after 6 minutes the thermoplastically deformed foam board removed.

After the mechanical division, molded foam parts are created at the seams, which have the contours of the multiple shape

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correspond. They serve, for example, as inserts in a packaging box for picking up shock-sensitive goods.

Example 3

Foam particles with an average diameter of 8 to 10 mm are produced from a mixture of 78 % of a copolymer of 77.2 % ethylene and 22.8 % acrylic acid tert-butyl ester, 19 % polyisobutylene with a molecular weight of 150,000 and 5 % talc and have a bulk density of 15 g / l.

The. Particles are exposed to X-ray radiation until they have a gel fraction of 65 % .

The foam part away are then heated in a metal mold for 5 minutes on IA o ⁰ C and do 50% of the original bed height zusammengeireßt. This gives homogeneous, firmly welded foam sheets which have a thickness of 10 mm and a density of 30 g / l.

A polyethylene pouch is placed on each side of a foam sheet lie of 100 / U strength. This plate comes in one Clamped deep-drawing device and heated to 140 ° C for 6 minutes. In connection then from below a deep-drawing mold is made, which gives the shape reproduces a pith helmet and is applied to the vacuum, approximated to the foam sheet so far that the foam sheet under thermoplastic deformation is close to the shape hugs. It is allowed to cool for 10 minutes at room temperature and removes a molded body which contains polyethylene foils as outer layers and has a foam layer on the inside. Of the Shaped body has the shape of a helmet and can be laminated used with fabric outer layers for the production of a pith helmet will.

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Claims (1)

.0.Z. 25 972 Claim Process for the production of foam moldings by heating plates or webs of foamed olefin polymers to temperatures above the softening point, shaping in the thermoplastic state and cooling the moldings, characterized in that plates or webs of welded, foam-like particles of olefin polymers are used which are crosslinked Shares included. * Badische Anilin- & Soda-Fabrik AG