DE1778103A1 - Process for the production of molded articles from foam-shaped isotactic polybutene or butylene copolymers - Google Patents

Description

Badische Anilin- & Soda-Fabrik AG

Our reference: O.Z. 25 476 Schs / Gn Ludwigshafen / Rhine, March 26th, 1968

Process for the production of moldings from foam-like isotactic polybutene or butylene copolymers

The invention relates to a process for the production of moldings from foam-like isotactic polybutene or (^ Butylene copolymers, in which foam-shaped particles are heated in molds and sintered.

For the production of molded bodies with a cell structure, in particular a known process introduced into technology in which blowing agent-containing styrene polymers are first pre-foamed and the pre-expanded masses after a short storage tent inside heated in a mold, so that the particles foam and sinter to form a molded body, which in the dimensions of the interior ^ cavity corresponds to the shape used. According to this process, it is possible to produce moldings with a complicated shape, how they are used, for example, as packaging inserts. However, this procedure has only proven itself in the case of styrene polymers proven. It has not yet been possible to use other cellular polymers, for example olefin polymers, sintering in molds with equally satisfactory results.

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Foam-like olefin polymers with a closed-cell structure are obtained, for example, by a known process in which the polymers are obtained within a continuously operating Mixing device, e.g. within an extruder, mixes with blowing agent and mixes the mixtures after leaving the extruder nozzle relaxed. With certain propellants it is possible to obtain cellular particles or webs according to this procedure, whose density is between 20 and 50 gram-liters.

However, it is not possible to use this method to complicate moldings.

¹ ^ produce ornamental shape. According to another mode of operation, the olefin polymers are heated under pressure inside a mold with blowing agents which decompose into gaseous products when heated; the molded body obtained, after cooling, is again brought to high temperatures so that it foams. However, only moldings of simple shape can be obtained by this method.

It is also known to produce foam bodies by heating P to produce foam-like particles containing crosslinked components from olefin polymers and sintering under pressure.

It has been found that foamed moldings can be made from foam-shaped isotactic polybutene or butylene copolymers obtained when foam-like particles of these substances are heated in closed molds until sintering.

Polybutene is also to be understood as meaning mixtures which contain at least 90 % (percent by weight), based on the mixture, of polybutene

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contain. Butylene copolymers are to be understood as meaning copolymers which have been prepared from mixtures containing at least 90% butylene.

As detailed tests have shown, the foam-like particles made of isotactic polybutene have a significantly wider softening range than corresponding particles made of high-pressure or low-pressure polyethylene or polypropylene. While these products, if they are in the form of foam-like products, slightly collapse and shrink when heated at a temperature at which the surface of the particles is not yet tacky enough to bond with other particles, foam-like particles behave made of polybutene much cheaper. The heat resistance and simultaneous surface tackiness is given within a temperature range of 15 to 2O ⁰ C. In contrast, foamed particles made from untreated polyethylene or ethylene copolymers sinter within a temperature limit of about 5. For this reason, it is not possible to produce technically useful foams by heating the untreated particles of the type mentioned. In contrast, this works very well when using foamed particles made of polybutene or butylene copolymers.

Another advantage of using foamed polybutene particles is that the softening point is approximately at 130 to 135 C, that is, well above the softening point of

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Polyethylene. This also increases the thermal stability of the foamed masses much higher, namely about IJO C.

The temperatures within which you can get the foamed particles can be converted into molded bodies made of foams by sintering, are at 115 to 135 ° C

The polybutene and the butylene copolymers are used in the form of foam-like particles whose diameter is between 3 to 50 mm, preferably 15 to 25 mm. Foam-shaped particles, which are sometimes also referred to as foam particles in technical parlance, are to be understood as meaning those particles in which the cell membranes consist of polybutene or butylene copolymers. Particles with a predominant proportion of closed cells (for example 90 to 95 % closed cells) are preferably used for the process. The foam-like particles are obtained by customary industrial processes, for example by mixing polybutene or butylene copolymers with a customary blowing agent (for example isobutane) in an extruder and pressing the mixture through a perforated nozzle and releasing the resulting strand of the foamed product is crushed immediately after leaving the nozzle. However, it is also possible to use particles which are obtained by heating mixtures of polybutene or butylene copolymers and customary blowing agents which decompose with the formation of gaseous products. Particularly suitable particles are those whose bulk density is between 5 and 200, preferably between 10 and 60, gram-liters.

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The particles of foamed polybutene or butylene copolymers In addition to the polymers, other components such as flame retardants, dyes, fillers, lubricants or others can also be used Polymers such as polyisobutylene. Sometimes it is advantageous to mix the foam-like particles with coarse-grained or to process fibrous fillers or reinforcing materials, as such For example, wood fibers or mineral fibers, other porous materials or fibers made from thermoplastics can be used in question. Coarse-meshed fabrics or grids, e.g. made of thermoplastics, can also be used as reinforcement inserts in incorporate the moldings.

The foam-like particles are heated in closed molds. It is to be understood as such shapes, the walls of which are firmly connected. The molds should be designed so that when the foam-like particles are heated, the air or other gaseous or liquid constituents can escape from the mold, but not the foam-like particles. It is expedient to use molds whose walls are perforated or those whose walls have nozzles with small-caliber openings built into them, through which the heating medium can penetrate into the mold and the air can exit from the mold. A particularly advantageous embodiment of the method according to the invention consists in using molds in which at least one mold wall is movable so that the contents of the mold can be pressed before, during or after heating. In a particularly advantageous embodiment of the method according to the invention, the foam-like particles are

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during or after heating from at least 2 sides in the mold is pressed against the center of the mold cavity.

Closed forms should also include the usual continuous working shaping devices understood who & ea how they for the known continuous production of molded bodies from finely divided foamed plastics use. Such

_ Devices consist, for example, of four F13Abftndern _# which are arranged in relation to one another in such a way that they form a channel. The foam-shaped particles are introduced into this channel at one end, then sintered and the foam strand obtained is discharged at the other end of the channel. The conveyor belts can be arranged in such a way that the particles are pressed together before sintering. The conveyor belts can also be divided into plate-like form as link chains. For the production of wide conveyor belts, mostly only two parallel conveyor belts are required, on the sides of which fixed or movable conveyor belts are required.

P arranged walls are arranged so that the system has a channel forms.

The foam-like particles should be heated to temperatures within the mold are heated, during which they sinter. These temperatures depend on the chemical structure of the polymer and the other additives. The temperature is generally between 110 and 140, preferably between 115 and

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The heating of the particles within the mold can take place with conventional heating media. So it is possible, for example, hot Introduce gases, steam or liquids into the mold. For example, one can use the molds, their inner cavity with the foam-like particles is filled, store in liquids in which the polymers are insoluble. Particularly suitable heating fluids are e.g. water-based mixtures, glycerine or aqueous salt solutions.

According to a particularly advantageous mode of operation, the heating medium passed through the mold cavity. It is expedient to introduce the heating medium on a side surface of the mold and lets it out on the opposite surface. For the production of complex moldings, it is sometimes advantageous to allow the heating medium to enter on several sides of the mold and to withdraw it on one side, for example at the bottom of the mold. The heating medium is after a beneficial and energy economical way of working in a cycle through the mold. This mode of operation has proven particularly useful in the case of continuous Execution of the procedure. J

But it is also possible to use the heating by probes or perforated Pipes, which are arranged between the foamed particles, to make, so that the heating - possibly also additionally - also takes place from the inside of the mold cavity. In this way, the heating can be used, particularly in the case of large shaped bodies intensive and, in the case of discontinuous work, the work cycle be shortened. The probes are removed before the particles are compressed.

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A simple way of working is to add hot steam to the Initiate forms. The heating of the particles inside the mold can also be done with infrared rays or by blowing in hot air take place. The particles can also be coated with small amounts of a substance that has a high dielectric loss has, e.g. water or aqueous salt solutions, and after the introduction be heated in the mold in the high frequency field.

According to a particularly advantageous mode of operation of the process, the particles are compressed in the mold by 5 to 60% of the original bulk volume. The pressing of the particles can be carried out before, during or, in particular, after the heating of the particles. Depending on the pressure applied, moldings are obtained from welded particles, some of which still contain cavities or which form a homogeneous mold.

The moldings obtained can be heated again after they have been removed from the mold, so that they foam further and thus a moldings with a lower density is obtained. The moldings can also be comminuted and the particles obtained reheated in molds under pressure.

By using polybutene or butylene copolymers, it is possible to obtain shaped bodies, which are flexible and whose weight per about 20-50 kg / m · ^5. The moldings have a particularly high impact elasticity and a low Druokver deformation rest. Foams produced in this way can

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Areas of application are used with advantage. For example, according to the method of the invention, upholstery, packing point, Manufacture floating bodies, thermal and acoustic insulation in construction, floating screeds, roof insulation or toys. The shaped bodies can also, e.g. with a heated metal wire, separated into individual sections, e.g. in foils or strips will.

The percentages given in the following examples are percentages by weight.

example 1

The inner cavity of a metal mold with 4 vertical boundary surfaces, the perforated bottom and top boundary surfaces of which can be moved towards the center, with the dimensions 400 χ χ 800 mm, is filled with foamed particles from an isotactic polybutene produced with Ziegler-Natta catalysts, melt index 0, 5, ether-soluble components 6 wt. #, Melting point 128 ⁰ C, filled. The particles have a size of 15 to 25 mm in diameter and a bulk density of 19 g / l. The foamed particles also contain 3 % talc.

The mold filled with the foam particles is stored in air at 125 ° C. for a period of 120 minutes. Thereafter, the upper and lower plate is moved towards the center, so that the loosely heaped particles are pressed together, occupy a Raun mm 400 χ 400 χ 400 to them.

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In this state, the mold is left at room temperature for JO minutes and then opened. A block of foam is removed. take, which consists of firmly sintered particles and has a density of 58.5 kg / nr. The foam block is cut into sheets of 1, 5 cm and 5 cm with a band knife. The plate sections have a high inherent strength and are very flexible. They can be rolled up and laid in a bent state. They are suitable as insulating material in construction and refrigeration technology, as floating bodies, as shock-absorbing material in packaging, as cushioning material, as inlays in composite elements, as under-wallpaper, as an under-layer, for the insulation of flat roofs, Cold rooms, refrigerators, refrigerated cars and the like. The foam blocks can also be cut into thinner sheets that can be used as inserts, as decorative material and the like.

Example 2

In a metal mold, the structure of which corresponds to the mold described in Example 1 and whose cavity is 400 × 400 4 100 mm, foamed particles with a diameter of 20 to 25 mm are filled. The particles have a bulk density of 22 kg / m 2. They consist of a mixture of 90% by weight of polybutene and 10% by weight of polyisobutylene, molecular weight 150,000. The polybutene used has a melt index of 1.40 % ether-soluble components, melting point 125.degree.

The particles are filled in such a way that the cavity of the mold is fully filled and the upper and lower movable surfaces are easy

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is present. In this state, air at 124 ° C is blown through the cavity from the top of the mold for 5 minutes at a rate of 400 liters / minute. The upper and lower plates are then moved towards the center of the mold so that the particles are compressed to about 50% of their bulk volume. After a cooling time of 20 minutes at room temperature, the foamed molding is removed from the mold.

A coherent, very elastic, tensile strength and stretchable foam body with a density of 45 kg / m 2 is obtained with the dimensions 400 χ 400 χ 50 mm. Cut from the molding Boards can be used as a base for floating screeds, for impact sound insulation, as insulation for vehicles against the Heat from the roof and as a shock shield in case of impacting bodies, as cushioning material, as inserts in Packaging, for the insulation of cold and heat pipes and the like can be used.

Example 3

The cavity of a metal mold structure similar to that described in Example 1, the inner cavity of which has the dimensions 50 × 50 × 50 cm, is filled with foamed particles of 15 to 20 mm in diameter and a bulk density of 18 g / l. The particles are made of a copolymer of 90 wt.% Butylene and 10 wt.% Ethylene, melt index 2, ether-soluble content of 50%, melting point 121 ° C. The particles also contain 3 % talc.

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The top and bottom plates that enclose the cavity lie on the particle. In this state, ■ steam at 125 ° C is passed through the mold for 10 minutes from the top. Then the upper and lower plate is moved towards the center so far that the cavity of the mold is now the Assumes dimensions 50 χ 50 χ 20 cm. In this state will Cooled for 50 minutes at room temperature and then the resulting Molded body removed from the mold.

"The shaped body has a density of 41.5 g / l. It consists of welded foamed individual particles and has a high tensile strength, elongation and flexibility. He is using a band knife cut into sheets of 3 cm thickness, which are used as cushioning material, e.g. when shipping shock-sensitive goods can be.

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Claims (2)

- 13 - O.Z. 25,476 claims 1. A process for the production of foamed moldings from isotactic polybutene or butylene copolymers, characterized in that foam-like particles of these substances are heated in closed molds until they are sintered. 2. The method according to claim 1, characterized in that the heated particles are compressed by 5 to 60% of the original volume before cooling. J>. Process according to Claim 1, characterized in that foam-like particles with a predominant proportion of closed cells are used as the starting material. Badische Anilin- & Soda-Fabrik AG, 109831/1761 ORIGINAL INSPECTED