DE2226783A1 - METHOD AND DEVICE FOR PRODUCING FOAM LAYERED MATERIAL - Google Patents

Description

DR. BERG DiPL,! NG. STAPF

β MUNICH 8O. IWAUKRKIRCHERS ^ R. <«J

22 499

Monsanto Chemicals Limited London, S.V / 1 / Great Britain

Method and apparatus for producing foam sheet material

The invention relates to a method for producing foam sheet material and to a An apparatus for manufacturing sheet material in which a foamed thermoplastic resin sheet is applied a flexible pad is piled up.

By extrusion of foamable thermoplastic Resins can be used to produce materials that are suitable for purposes where a light, elastic, cheap and easy to handle web material is required, are particularly well suited. For numerous For purposes of use, for example for carpet underlays, the foamed material is expediently placed on an underlay up ^ 'reports. Such documents are common

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connected to the foam by means of an adhesive, but this incurs additional costs for the adhesive and an additional manufacturing step is required.

The invention provides a method, when used, the production of a layer material from a thermoplastic Foam layer and a flexible pad can be carried out in a single operation.

In a method for producing a layer material from a layered on a flexible substrate, Foamed thermoplastic resin is provided according to the invention that a foamable thermoplastic resin is extruded through a slot nozzle into a passage through two opposing Areas is limited, one of which is fixed and the other by the surface of a flexible base material is formed, which is driven to rotate about an axis running parallel to the slot nozzle Roller rests and is transported through this in the squeezing direction, the dimensions of the passage and the movement of the base material are coordinated so that the foaming resin over at least a part

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its passage between the two surfaces remains in contact with both surfaces and that the contact between the resin and the base material takes place as long as the temperature of the resin is still above the softening point and before the foaming of the resin is complete.

The invention also provides an apparatus for producing a layer material from a flexible base material and a layer of foamed synthetic thermoplastic resin having one of one Extruder-fed slot nozzle, which is delimited directly into one by two opposing surfaces Passage opens, one surface being stationary and the other is formed by the surface of a roller which extends around one parallel to the slot nozzle Axis is rotatable and in operation for transporting the flexible base material placed on it in the The direction of squeezing past the slot is used.

The roller can be driven at a speed that is independent of the extrusion speed of the resin. Of the Drive can be by means of an external drive source or a motor or by the frictional contact between her and the one pulled over the roller in this case

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Underlay material.

An embodiment of a device according to the invention for producing a layer material of the aforesaid Art is shown in the drawing, the only figure of which is a schematic cross-sectional view of the Device shows.

The device has a limited by upper and lower lips 1 and 2 slot die for extruding a foamable resin 3 in a passage which and a driven on the surface smooth by a plane at an angle of 6o ° related to the plane of the extruder outlet face ¹ J, Roller 6 guided document material 5 is limited. Optionally, a pattern roller 7 can also be provided, by means of which any desired surface pattern can be produced on the surface facing away from the base.

The softening point of the resin depends not only on the type of resin, but also on the amount of in the resin remaining blowing agent, as this is often called Plasticizer or plasticizer is effective. This factor is therefore in determining the temperature,

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in which the resin is brought into contact with the base material.

In an advantageous embodiment of the inventive method is the temperature at which pressed the foamable resin between the lips and is engaged with the flexible backing material in contact between Io and 80 ⁰ C, preferably from 2o to 5o ° above the softening point of the resin. ·

To maintain a sufficiently high temperature when merging the support material with the foamable Resin, it appears expedient, the driven roller and thus the support material guided on its surface to one in a range of lo ° C around the softening point of the resin, preferably up to lo ° C to heat the temperature below this point.

The dimensions of the passage are chosen so that the resin when it comes into contact with the substrate is above the Has the softening point and the foaming has not yet taken place at this point in time or at least not yet completed. In practice this means that there is sufficient back pressure in the passage

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is generated, so that the foaming of the resin prevents or is only partially possible. For this purpose, the passage can be given a constant width in the extrusion direction. This can be achieved in that the fixed surface has a concentric with the driven roller, obtained concave or cylindrical profile or, if the fixed surface is flat, by the fact that the roller has such a diameter that its surface curvature is negligible over the length of the passage. In other words, this means that the roller is stationary when it is flat Area should have such a diameter that the increase in the width of the passage in the direction of extrusion den Build up of sufficient back pressure in the passage is not affected. In many cases it is also useful to form the fixed surface so that it forms a constriction to in the area of the passage between the constriction and the slot nozzle to generate sufficient counter pressure.

The gap width of the slot nozzle used according to the invention is about 0.1 to 2 mm and preferably 0.3 to 1 mm. With such dimensions of the slot nozzle is a passage with an extension of 0.5 to 30 mm, such as e.g. 1 to 2o mm in the extrusion direction usually sufficient

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ching. The width of the opening can be in the extrusion direction vary. As long as the extension of the passage in the extrusion direction cannot be changed it can be 0.5 to 15 mm, in particular 1 to 5 mm. If the passage is narrowed, its thickness can be reduced to 0.1 mm in the region thereof, but with a narrowing to one thickness less than 0.2 mm is not preferred in many cases.

In the invention, rollers with diameters between 15 and 12o mm, preferably between 2ο and 9ο mm, are used. The choice of the diameter depends to a certain extent on the length of the passage in the direction of extrusion. If this length is in the upper range of the listed lengths, i.e. between about 15 and 30 mm, then the roller points expediently also one in the upper part of the stated range, i.e. between 50 and 120 mm Diameter on.

The driven roller preferably has a smooth surface, but it can also have any profiled surface which then exerts a different pressure in places on the base material. To this

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In this way, a different degree of adhesion of the foam to the substrate can be achieved. Preferably the roller is loaded towards the stationary surface by means of a spring suspension or the like in order to maintain it to support sufficient back pressure within the passage.

The properties of the finished foam layer can be changed by changing the peripheral speed of the roller influence. For example, if the roller is driven so that the linear speed of the base material is slower than the rate of extrusion of the resin from the slot nozzle, the resin remains in the passage longer than if the roller were driven at a higher speed. In this case, a is created in the passage so strong counterpressure that most of the foaming takes place beyond it. Through control the circumferential speed of the roller can therefore be the degree of foaming of the resin when it emerges from the Passage and thus the thickness of the finished layer material influence. The peripheral speed can be depending on the extrusion speed and the type of product to be manufactured in a wide range between about 0.15 m / min or below to about 15 m'i.ixn, for special ones Purposes, if necessary, even about it, choose.

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Mostly the range is between about 0.6 and 9 m / min, in particular between 1.5 and 4.5 m / min for normal Purposes.

After exiting the passage and before the final solidification of the thermoplastic resin, the Resin side of the layer material advantageously with a second Roller are acted upon, which has a flat or profiled surface. That extra roller comes that is, on the surface of the thermoplastic resin layer facing away from the support and gives it a desired surface structure. The additional roller is included to produce a smooth surface provided with a smooth peripheral surface and preferably cooled. With an appropriately profiled roller can make a waffle pattern. In this way, the surface of the resin layer can be given a variety of patterns.

The document material is flexible, i.e. it can be bend without breaking. It is preferably so flexible that the ends meet one another about 30 cm, better still about 15 cm long sample at a temperature of 20 ° C bring them together and then back into the stretched position

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Let the shape bend back without breaking the specimen. A suitable document material is, for example a woven or non-woven fabric made of natural or synthetic fibers or a material such as paper or a polymeric film. The type of document material depends largely on the ultimate purpose of the layer material produced. Is this intended for high loads, such as those for example occurs with carpet underlays or insoles Use a coarse cotton or jute fabric as a base material. Are in the intended use If less stress is to be expected, the underlay material can be a lighter, woven or non-woven sheet material made of natural fibers or, preferably, artificial fibers made of cellulose ester, nylon or an acrylic compound, a strong paper or a thermoplastic Foil, such as made of polyvinyl chloride, polystyrene or polyethylene. When using a polymer film however, care must be taken that the polymer has a sufficiently high softening point so that the film is not destroyed by the heat applied during extrusion.

The thermoplastic resin is, for example, a polymer

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or mixed polymer of a vinyl or vinylidene monomer, preferably a hydrocarbon monomer such as monomeric ethylene, propylene, butadiene, styrene, vinyl toluene or u- methylstyrene or a substituted monomer such as
Acrylonitrile, vinyl or vinylidene chloride, vinyl acetate,
Methyl acrylate, methyl methacrylate or ethyl aerylate. Furthermore, the resin can be aliphatic, for example a polyolefin such as high or low density polyethylene, or a copolymer of an aliphatic olefin such as
Be ethylene or propylene with one of the substituted monomers listed above. The resin can, for example
be an ethylene-vinyl acetate copolymer, such copolymers or optionally polypropylene or
Low density polyethylene particularly preferred resins
are. The process is also suitable, for example, for polyvinyl aromatic resins, ie polymers or copolymers of vinyl aromatic monomers such as
Styrene, chlorostyrene, vinyltoluene or <χ -methylstyrene.
The copolymers of vinyl aromatic monomers with another olefinic monomer, such as, for example, acrylonitrile, vinyl chloride, vinyl acetate, methyl methacrylate or ethyl acrylate, are also suitable. In addition, a reinforced polystyrene can be used to which a natural or synthetic rubber, for example, has been added before or after the polymerization. Among the polyvinylaro

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matic resins, polystyrene is best suited.

The foamability of the used in the process according to the invention Resin is made by adding a blowing agent, usually a low-boiling substance or a chemical blowing agent achieved. In many cases, the propellant is a volatile substance, which under normal atmospheric conditions, i.e. at 20 ° C and 1 atm pressure, is gaseous or vaporous and below that before extrusion prevailing pressure is dissolved in the molten or semi-molten thermoplastic resin. The propellant can also be pentane or a pentane fraction which is liquid under normal conditions. Examples of usable volatile substances are lower aliphatic hydrocarbons such as methane, ethane, ethylene, propane, butane, Butylene or a pentane, lower alkyl halides such as methyl chloride, trichloromethane, dichlorodifluoromethane or 1,2-dichlorotetrafluoroethane, also acetone and inorganic Gases like carbon dioxide or nitrogen. For foam layers with a density of 24o to 48o kg / mr Nitrogen is particularly suitable, while for a density between 16 and 160 kg / m ^ it is the most suitable Propellants are butane, isobutene and dichlorofluoromethane. Suitable chemical blowing agents are, for example

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wise bicarbonates such as sodium bicarbonate or ammonium bicarbonate, as well as nitrogen-releasing nitrogen compounds such as dinitrosopentamethylene diamine or barium azodicarboxylate when heated. The admixture of the blowing agent, based on the weight of the resin, is usually 3 to 30% by weight _3, in particular 7 to 20% by weight of JS. When using polyethylene Io% butane, for example, to 15 wt. Added. When using nitrogen as a propellant, smaller additions of, for example, 0.3% by weight are sufficient . The blowing agent can be mixed into the resin in various ways. Thus, in the case of a solid propellant, the resin particles can be dusted with this or, in the case of a liquid propellant, soaked with this before they enter the extruder. When using a volatile substance as a blowing agent and a screw extruder, the blowing agent is preferably injected into the extruder barrel under pressure.

The resin preferably additionally contains a core-forming ^ - the agent which contributes to the formation of a large number of fine cells. Suitable as core-forming additives numerous different substances such as finely divided inert peptides, for example silica, talc or alumina, optionally together with zinc stearate.

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Calcium salts of alophatic or aromatic carboxylic acids such as calcium acetate or calcium benzoate can be used be used. Smaller amounts of a decomposing at the extrusion temperature with the release of a gas Substance are also useful. Examples of the latter type of nucleating agents are azodicarbonamide and sodium bicarbonate, the latter optionally together with a weak acid such as tartaric acid or citric acid. Another effective nucleating agent Boric acid is added. Usually there is an addition of small amounts of the nucleating agent, about up to 5% by weight, based on the resin, is sufficient.

The extrusion temperature, i.e. the temperature of the slot nozzle and thus also of the resin, is to a certain extent Dimensions depend on the softening point and the rheological properties of the resin. Temperatures are common between 9o and 18o °, in particular between 95 and 16o ° C, is appropriate. When extruding foamable For example, polyethylene is usually best at a temperature in the range between 100 and 130 ° C.

Pressures of more than 17 _S 6 kp / cm are required for extrusion

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especially those between 17.6 and 352 kp / cm are used. The range between 21.1 and 141 kp / cm2 is best suited here.

The foam resin produced preferably has a predominantly closed cell structure, that is to say that the majority of the cells are closed. For example, the cells have diameters between 0.025 and 12.5 now. A fairly small average cell diameter in the range between 0.05 and 0.12 mm is most favorable. The density of the foam can be determined within a wide range. For certain purposes, a density of 8.0 to 32o kg / m ^ or even less is appropriate, while for other purposes a density between about 160 and 800 kg / m or even more is suitable. Preferably, however, the density is between about 16 and 560 kg / nr, with the range between 3o and k is 80 kg / nr often most suitable.

The products of the method according to the invention are for those purposes where flexibility is required along with dimensional stability are particularly well suited. They are therefore particularly suitable for the production of insoles, carpet underlays and the like.

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Below is the invention by way of example explained:

Example:

The example describes the application of the invention Process for the production of a layer material from a foamed ethylene-vinyl acetate copolymer and a coarse cotton fabric.

An extruder with a cylinder diameter of 38 mm and a slot nozzle of 150 mm transverse dimension was used for the extrusion of the resin in the arrangement described above with reference to the drawing, but without the pattern roller 7 » used.

The gap width of the slot nozzle was 0.5 mm, and the The passage into which the resin was pressed after exiting the nozzle had a length of 3 mm at an im substantially constant width or thickness of 1.5 mm. The roller was 25 mm in diameter and was driven at a peripheral speed of 2.8 m / min.

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The resin used for the production of the foam layer was an ethylene-vinyl acetate copolymer containing about 12 wt.% Vinyl acetate, with an addition of 1% calcium acetate as a core-forming agent. The mixture was extruded with a throughput of Ho g / min, nitrogen being injected into the extruder barrel under a pressure of 50 kg / cm. The temperature was in the extruder barrel 15o ° C and at the slot nozzle opening 12Q ⁰ C.

on the driven roller heated to 90 ° C. was a 0.3 mm thick cotton fabric guided, the roller was arranged in such a way that the fabric is firmly attached to the The end face of the lower porous jaw was located and was used to transport the tissue up to the slot nozzle and then away from this with a peripheral speed of 2.4 m / min driven.

The resin was forced into the passage between the fabric guided on the roller and the upper porous jaw. The foaming resin adhered to the fabric, so that a 150 mm wide and about 1.5 m thick layer material was created. On completion of the foaming, the foam had a density of ¹ JoO kg / m 2. The liability between the

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Foam and the cotton fabric was excellent. That The resulting product was flexible and elastic and was well suited as an insole, for example.

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Claims (27)

Patent claims: 1. A method for producing sheet material, thereby characterized in that a foamable thermoplastic resin through a slot nozzle into a Passage is squeezed out, which is limited by two opposing surfaces, one of which stationary and the other one through the surface on one that runs parallel to the slot nozzle Axis rotating driven roller resting and transported through this in the squeezing direction, flexible material material is formed, with the dimensions of the passage and the movement of the backing material are matched so that the foaming resin over at least part of its passage between the two Surfaces on both surfaces remain in contact and that the contact between the resin and the backing material takes place as long as the temperature of the resin is still above the Softening point and before the foaming of the Harz is complete " 2. The method according to claim 1, characterized in that that the roller is rotating at such a speed - 2o 209 8-8 4/1 186 · · ■: - 2ο - is driven that the linear speed of the base material is slower than the rate at which the resin is extruded from the slot die. 3. The method according to claim 1 or 2, characterized in that the foamable resin at a by 2o to
Temperature 50 ° C above its softening point
is extruded from the slot nozzle and brought into contact with the backing material. 4. The method according to at least one of claims 1 to 3, characterized in that the roller on one to
at lo ° C below the softening point of the resin
Temperature is maintained. 5. The method according to at least one of claims 1 to ¹ J, characterized in that the roller is driven at a peripheral speed between o, 6 and 9 m / min. 6. The method according to at least one of claims 1 to 5, characterized in that a roller with a profiled surface is used. 7. The method according to at least one of claims 1 to 6, characterized in that the resin-side surface - ρ "_
209884/1 1 86 of the layer material after exiting the passage and is acted upon by a pattern roller before the final solidification of the resin. 8. The method according to at least one of claims 1 to 7, characterized in that the flexible support material a woven or non-woven fiber material is used. 9. The method according to claim 8, characterized in that a loose cotton fabric as the flexible underlay material is used. 10. The method according to at least one of claims 1 to 9, characterized in that the resin is a polymer or copolymer of a vinyl or vinylidene monomer used. 11. The method according to claim Io, characterized in that that a polymer or copolymer of an aliphatic olefin is used as the resin. 12. The method according to claim 11, characterized in that 209884/1 1 86 that the resin is an ethylene-vinyl acetate copolymer used. 13. The method according to claim lo, characterized in that that the resin is a polymer or copolymer of a vinyl aromatic monomer is used. 14. The method according to claim 13, characterized in that the resin is polystyrene or an acrylonitrile-butadiene-styrene copolymer used. 15. Method for producing a layer material, im essentially as described in the previous example. 16. Device for producing a layer material from a flexible base material and a layer of foamed thermoplastic synthetic resin _s characterized by one fed by an extruder. Slot nozzle (1, 2) which opens directly into a passage (H) delimited by two opposing surfaces, one surface being stationary and the other being rotatable through the surface of an axis parallel to the slot nozzle during operation for transporting the flexible underlay material (5) placed on top of it in the direction of extrusion past the slit serving roller (6) - 23 - 209884/1186 is formed. 17. The device according to claim 16, characterized in that that the roller (6) with a variable or constant Drive is provided. In that the passage ⁽¹ comprises O constant thickness 18. The apparatus of claim 16 or 17, characterized. 19. Apparatus according to claim 16 or 17, characterized in that a constriction is formed in the passage (4) is. 20. Apparatus according to claim I9, characterized in that that the constriction is formed by a corresponding training on the fixed surface. 21. The device according to at least one of claims 16 to 2o, characterized in that the roller (6) has a has a profiled surface. 22. Device according to at least one of claims 16 to 21, characterized in that the roller (6) through ■ ■ ■ ■ - 24 · - ■■ 209 88 AM 186 a device provided for this purpose is loaded in the direction of the fixed surface, 23. Device essentially as described above with reference to the drawing. 24. Method for producing a layer material from a flexible base and a foamed thermoplastic Resin using an apparatus according to at least one of claims 16 to 23. 25. Layer material, characterized in that it using a method according to at least one of claims 1 to 15 and 24 is made. 26. Insole, characterized in that it is made from a layer material according to claim 25. 27. Shoe, characterized by an insole according to Claim 26. 209 884/1186