DE2143836A1 - Process for the production of pipes that are put together - Google Patents

Description

The invention relates to composite tubes.

The manufacture of composite pipes, which contain at least one layer of a foamed plastic material have, for example, in British patent specification 1 151 884 and in British patent applications 9956/69, 9957/69, 3923/70, 8478/70, 12212/70 and 29624/70

One method of making such tubes, which is described in British Patent 1,151,884, is in that one rotates a hard core tube about its longitudinal axis and moves it along its longitudinal axis, at the same time

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a flexible tape which is coated with a foamable composition; c "tangential to the rotating core less than _o
tube and at an angle of / 90 to the longitudinal axis of the core tube so that. the coated flexible tape forms a helically wound envelope, the foamable composition coming to lie in the annular space thus formed between the core tube and the wrapped flexible tape, and allowing the foamable composition to cure. The tube obtained has a layer structure, it essentially consists of an inner skin (the core tube) which surrounds the cavity of the tube, a layer of foamed plastic material around the inner skin, and an outer skin surrounding the foamed plastic material, which consists of a spiral of 3 flexible bands with the edges of the adjacent turns of the band overlapping or abutting one another.

To prevent or reduce the escape of foam from the annular space a flexible bridging strip can be wound along the helical joint line of the wound flexible tape and / or a sealing strip on the outside of the helical butt line of the wrapped flexible tape

to be ordered.

A number of materials are suitable as a core tube and / or as a flexible band which surrounds the foam layer of the pipe. For example, paper, cardboard, woven and non-woven barrel materials, such as ζ, B. Textiles and other Pasermaterialisn, metals and plastics (which for example can be reinforced with glass fibers). The material used can be simple or have a complicated structure »For example, it can have a layer structure, as is the case with a plastic-coated paper or a plastic-coated metal foil is the case. “It can also be a

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be simple or complex in shape »For example it can have longitudinal ribs and / or transverse ribs on one or both surfaces = a form of such a layer structure can for example have a corrugated layer of a material such as cardboard or asbestos, with a or is laminated with several flat layers of the same or a different material to form a "sandwich", which, for example, particularly desirable "impact resistance or has temperature resistance properties. If necessary, the material can be used with a Dye * with a waterproofing agent, with a rotting agent or with a size be pretreated. In the case of textile fiber materials, such as e.g. plucking or glass fibers, for example, can be impregnated be made with a thermosetting resin, which is then cured after winding into the shape of a tube can be. In general, the materials mentioned above are also suitable for a bridging strip or sealing strip, of course is a thick material, such as a corrugated layer or a laminate that has a corrugated layer, less suitable.

As used herein, the term "flexible" merely means that the tape or tape so designated Strip is sufficiently flexible that the tape or strip can be wrapped around a diameter like it is necessary in the manufacture of the pipe according to the invention.

The foamed or foamable composition can be based on a polymeric material. These materials are detailed described in the above mentioned patents and patent applications. True, the use of thermoplastic Polymers, such as, for example, “polyamides, polyesters, polyacetals”, polycarbonates j polysulfones and polymers and copolymers from

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Ethylenically unsaturated monomers, such as ethylene, propylene. 4 ~ methylpentene - 1 _f styrene, vinyl chloride _s acrylonitrile s butadiene and acrylic acid esters, not excluded, but it is generally "preferred to use foamable compositions based on curable polymeric systems, such as ζ" 3, curable polyurethanes. Phenol / Formaldehyde resins, amine / formaldehyde resins, epoxy resins and compositions of this type which have at least one polymerizable vinyl ether containing at least two yinyl groups per molecule

in

as described in British Patent 991,970. The method is particularly suitable for use with polyisocyanurates », of this kind. v / ie them for example in British Patents 1,146,661, 1,184-893 and 1,223,415.

The foamable compositions can be processed in such approaches _for the hard or flexible foams result. Rigid foams are generally preferred because they generally have more favorable physical properties such as e.g. Pressure resistance. The foams can be open-cell or closed-cell foams. However, closed-cell foams are generally preferred, since in general the thermal insulation properties of foams are better ^ the higher the content of closed cells *

Foamable or look compositions based on Thermoplastics are generally applied hot, that is, at a temperature above their softening point, they will after sufficient foaming has been achieved, hardened or solidified by letting them cool. Foamables Compositions based on curable systems, on the other hand, can be applied hot or cold, and it can further heating, cooling or other suitable treatment

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_"1:?., ¹ JIf- used to effect the cure or control Examples of such compositions are ZussmniensetEUij.gen au.f the basis of polyurethane and polyisocyanurate cj ^r anu: catbildenderi G-emic polyurethane chauiübildungsgemische contain GeV. , ^r öhnlich an organic polyisocyanate _s an organic ?? olyol _f a blowing agent and other conventional additives j such "B. catalysts and surfactants _and polyisocyanurates chaucibildungsgemis before are generally based on the same components as the conventional polyurethane mixtures ₄ but they contain a Isocj ^ anate polymerization catalyst and a considerable excess of polyisocyanate over the isocyanate-reactive materials.

In various of the above-mentioned patents or » Patent applications were the use of an adhesive in the manufacture of, for example, the core tube or during application of the power strip to close the gap described between the adjacent edges of the flexible tape “Although it may be appropriate, immediately before the Winding, for example, the core tube or the winding up of the Sealing strip to apply an adhesive, as for example is described in British patent application 29624/70. but this is sometimes inconvenient. For example, if a polyurethane foam is used. then can Difficulties arise with the use of an aqueous glue, since a reaction between the aqueous solvent and the foam occurs, ^ unless precautionary measures are

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dripped are (they KSS / come into contact "The use of a Druekklebstoffs, d ₆ h _e an adhesive which produces an adhesion only in that it is pressed under pressure between two surfaces, disadvantages with respect to" the handling, it has now been found that it is beneficial. to use a veranlaßbaren by heat for bonding adhesive _t called a heat adhesive kura in! Edition »

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Thus, according to the invention, there is a method of manufacture a composite tube., which has a.-foam layer which is held together by a skin of a helically applied flexible Ba. "ids v / irdj proposed which The method is carried out by rotating a hard pipe about its longitudinal axis and along its longitudinal axis moves, while at the same time a flexible tape coated with a foamable composition tangential to itself rotating pipe and at an angle of less than 90 ° to the longitudinal axis of the pipe, so that the edges are axially adjacent turns of the coated tape overlap or butt against each other and a spiral wound Form envelope around the pipe, the foamable composition comes to lie in the annular space thus formed, and that the foamable composition is foamed and cured leaves. Bae method is characterized in that at least one of the surfaces of the hard tube and / or the Bands is coated with a covering of a substantially tack-free thermal adhesive.

The adhesive used is one that is largely tack-free prior to gluing, so that the material to which it has been applied can be conveniently handled. Adhesives ₇ which are suitable for this purpose (i.e. ₅ which can be applied to a surface and rendered tack-free, but retaining their adhesive properties when heated) are known and described in the literature.

As examples of heat adhesives made from thermally curable plastic resins, there should be mentioned those based on Isocyanate and epoxy resins *! based. Choosing a suitable one thermally curable adhesive in which the adhesion is caused by crosslinking induced by high temperatures It depends on the temperature, which is at the

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Production is possible or appropriate. In particular when foamable compositions are used in which the foaming and curing is accompanied by considerable heat generation, the heat generated by the exothermic reaction can be sufficient to activate the adhesive and cause adhesion To effect adhesion - additional heat can then be applied, for example by using a heated mandrel and / or by applying radiant heating to the outside of the tube or the inside of the core tube. It has been found particularly convenient to use as the thermally curable adhesive such that auehärtet at a temperature between about 80 and 120 ⁰ C.

An isocyanate is u, U _c a particularly suitable thermally curable adhesive, because it is compatible with the preferred polyurethane or polyisocyanurate foam. Such an adhesive generally contains an isocyanate prepolymer having a molecular weight of the order of 2,000 to 4,000. These compounds are applied to either or both of the parts to be bonded in either a solvent system or in a solvent-free system and allowed to "dry", one partially Curing takes place in a known manner (see "3? Reatize on Adhesion and Adhesives" edited by RL Patrick, 1969 Chapter 3). Modified isocyanate adhesives, in which the properties of the isocyanate have been altered in a desired manner by the incorporation of other materials such as polyester, can also be used in accordance with the invention. Activation is effected by heating, but it can also be assisted by the use of a chemical activator which is water (but preferably not if polyurethane is used, as an undesirable reaction

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can occur} or a crosslinking agent in a non-aqueous Medium can act.

Thermoplastic adhesives can also be used. Such adhesives Bind ;, preferably those which, at a temperature between 50 and 150 ⁰ C, preferably 80 and 12O ⁰ Cj ^ soften so that they are sufficiently tacky "Such material is also generally known. The material can be "tailored" for a particular requirement, for example by mixing together polymers with the same basic unit but with different molecular weights and / or polymers with different basic units. The adhesive can be applied to the substrate, for example, by applying a hot coating _f, for example by spraying or dipping into the molten polymer, and then allowing the thermoplastic adhesive to cure by cooling to a non-tacky state, or by using a solution of the polymer or dipping the substrate in a solution of the polymer, the solvent then being removed, usually by evaporation, so that a tack-free layer of the thermoplastic material remains on the substrate.

Examples of such thermoplastic hot melt adhesives are polyvinyl acetate, polyvinyl chloride, polyolefins (such as * polyethylene) and interpolymers thereof. The adhesive materials are compounded for the appropriate softening point.

Adhesives as generally described above are particularly useful in making the core tube for the composite tube and in applying a strip of wire outside on the spiral joint line of the flexible outer skin of the composite tube.

Another surprising use of a thermal adhesive

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* the manufacture of the composite tubes described above lies in improving the adhesion of the foamable material to the core and / or the flexible tape that makes up the foam surrounds. Pie inmate kar.n by choosing his adhesive apply promoted, which is compatible with the foam and preferably is also chemically reactive to create a strong cross-linked bond between the foam and the material of the flexible Achieve bands au. It has been found to be particularly advantageous to those surfaces of the core tube and / or of the flexible tape to coat with an isocyanate adhesive that come into contact with the foam, in particular when the foam is a polyurethane foam. This adhesive is preferably used prior to being brought into contact made clot-free with the foam. The adhesion is then effected when the adhesive is heated or by the Presence of curing agents in the foam is activated. While an isocyanate adhesive is preferred, other adhesive materials can be used for this purpose,

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The use of a water / permeable adhesive material is particularly important in the manufacture of pipes that contain polyurethane or other foam that undesirably reacts with water that may be associated with the material of the core pipe, flexible tape or other components «In particular, paper, which is a suitable material for the production of core pipes and flexible tapes, usually contains a small amount of water _for the transition to the foam, preferably prevented by a water-impermeable layer, which is conveniently the adhesive,

It is very convenient that essentially all surfaces the material (the core tube, the flexible tape, the bridging strip or the sealing strip) the adhesive

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are to be made, coated with the adhesive and that the adhesive is rendered non-sticky during the manufacture of this material. However, care must be taken that if a mandrel is used to support the core tube _3, the adhesive does not come into contact with the surface of the mandrel.

In the production of a composite pipe using the method according to the invention, a tack-free coating of a thermoplastic adhesive ( "Heatfix", represented by Samuel Jones and Co. _a Ltd) which can be activated by a Tempe ~ temperature of 85 C, on paper applied, which was later used as a flexible tape and as a sealing strip. An isocyanate adhesive was used in the manufacture of the core tube. The manufacture of the pipe according to the invention is shown schematically in Pig, 1 of the accompanying drawings. The surfaces coated with adhesive are cross-hatched. The paper used was covered with a corona discharge treated polyethylene layer on the surface that came into contact with the foam. The polyethylene layer reduces the transfer of water from the paper into the foam. (As explained above, this covering can be omitted if the adhesive itself forms a waterproof barrier.)

According 3? Ig _t 1 v / ith the hollow mandrel 1 internally with hot air (about 10O ⁰ C) were charged, which escapes through small holes from the interior of the mandrel into an annular space between the mandrel surface and the core tube "The first layer 2 The core tube, which is produced in situ, is wound onto the mandrel (with the adhesive side facing outwards, ie facing away from the surface of the mandrel) so that the edges of adjacent turns of the shell abut against one another. The second layer 3, which is coated with adhesive on the side that

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later comes into contact with dsm foam, is wrapped on the first layer of the JC9r.nrc.:hr&· v / i θ shown, and “was such that the R ^; rnd-ar not? .us9iuni-3nfall. The flexible tape 4 is ^{coated on its inner 1} surface, ie on the surface that comes into contact with the display, with a suitable adhesive for this S-phsum (for example an isocyanate cycle agent.:. "For polyurethane foam) Sealing strip 5 is also coated on its inner surface so that an adhesion and seal between two adjacent edges of the wrapped flexible bend will cool, although a notified adhesive with a longer open time is preferred for the sealing strip to allow relative movement between the adjacent edges. Allow turns of the flexible tape immediately after winding. The foam 6 ν / ir α applied by a suitable nozzle to the surface of the flexible tape, and was preferably in a state that the winding and hardening did not complete before not the laminate is formed by entrapping the foam between the core tube and the flexible tape.

The exothermic heat from curing polyurethane can produce a temperature sufficient to activate the adhesive is high, but infrared heaters 7 may also be required to supplement this heat source and to provide a rapid activation of the data. "

It should be understood that it is of course not essential that all of the above-described features of the invention be applied at the same time. So it may be enough glue Use when making the core tube or when applying the sealing strip. Furthermore, it is not necessary that the same adhesive is used throughout «For example an isocyanate adhesive can be applied to 3 and 4 if a polyurethane foam is used., while a

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Epoxy resin on 2 and 5 can be used. In particular because of the insulating effect of the foam, it can be inexpedient to use a thermoplastic adhesive for the core pipe unless precautions are taken, such as the use of suitable cooling devices, such as a locally cooled mandrel surface, through which the setting of the thermoplastic adhesive can be influenced .

In a second experiment _5, in which the operating conditions were essentially the same as above, the core tube was made from a laminate, namely from a corrugated asbestos layer, which was sandwiched between an aluminum foil and paper. The manner of feeding and the arrangement of the layers in the laminate are shown in FIGS. 2 and 3, an aluminum foil 9 being connected to the corrugated asbestos layer 10 by a suitable adhesive. The second layer consists of paper, as in the previous example.

2? Ig _e 3 is a section on the line AA of Pig "2 showing the formed tube which consists of a laminate that is composed of an inner aluminum foil 9» a corrugated asbestos layer 10 and an outer paper layer. 3 The mandrel 1 is perforated so that hot gas can escape from the inside to the outside, which gas acts as a lubricant so that the core tube and possibly also the entire assembled tube can slide on the mandrel. According to the drawing, the core tube is kept away from the mandrel by this gas (not true to scale) »

Claims

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Claims (1)

Claims 1 * 1 method of making a composite pipe, which has a foam layer surrounded by a helically wound flexible tape, the method is carried out by rotating a hard pipe about its longitudinal axis and moving it along its longitudinal axis, simultaneously placing a tape coated with a foamable composition tangential to the rotating pipe and in at an angle of less than 90 ° to the longitudinal axis of the pipe, such that the edges of adjacent. Turns of the coated tapes overlap or abut one another and the tape is wrapped in a spiral wrap forms the tube, wherein the foamable composition comes to lie in the annular space formed thereby, and that one the foamable composition can foam and cure, characterized in that at least one of the surfaces of the hard tube and / or tape with a covering of a substantially tack-free heat-activatable adhesive is provided. 2. The method according to claim 1, characterized in that the foamable composition due to an exothermic Reaction foams and hardens. 5. The method of claim 2 _t characterized in that the foamable composition is a polyurethane or 1st Polyisocyanuratzusammensetzung. 4. The method according to claim 2 or 3, characterized in that the activation of the heat-activatable adhesive is caused at least in part by the heat generated by the exothermic reaction. 209810/1366 - -14 - 5 «Method according to one of the preceding claims _? characterized in that the adhesive is a thermally curable resin which cures ^{between 80 and 120 0} _{C 0} 6 »Method according to one of the preceding claims, characterized characterized in that the adhesive is an isocyanate based adhesive. 7. The method according to any one of the preceding claims, characterized in that the adhesive coating on all surfaces is applied, which come into contact with the foamable composition. OR, INS-H.ί ^: .; .-. ^ 0 \ Λ. · Ί: Ο. 3. BTAEGt * 209810/1366 To. Lee rsei ie