FR2520477A1 - SHAPE PIECE CAPABLE OF LOW-LENGTH SHREDDING SUCH AS SOFT PIPE CAP CUFF AND ANALOGUE - Google Patents

Abstract

A. PART OF SHAPING CAPABLE SHAPE OF LOW LENGTH SUCH AS A CAP, FLEXIBLE HOSE, SLEEVE AND THE LIKE, B. PART CHARACTERIZED IN THAT IN WALL 2 ARE ARRANGED, EXTENDING LONGITUDINALLY AND DISTRIBUTED ON THE PERIOD, ELEMENTS 3 HAVING HIGHER TENSILE STRENGTH AND LOWER ELONGATION. C. THE INVENTION CONCERNS THE MANUFACTURE OF SHAPED, SHRINKABLE PARTS IN EXTRUDED AND CROSS-LINKED MATERIAL.

Description

"Shape-capable piece of shrinkage of short length such that

  The present invention relates to a short-length, shrinkable-shaped piece such as a cap, hose, sleeve, and the like, made of extruded and crosslinked material. Such shrink-shaped pieces are general rule, manufactured by making by injection

  or extrusion a blank which is then subjected to

  culation and enlarged in this reticulated state, after which

  is definitively fixed in this enlarged state by cooling

  dissement. It is already known (patent DE 188 510), for the manufacture of flexible tubes shrinkable from thermoplastic masses, to heat the flexible pipe, extruded or injection molded, of reduced diameter, to widen it by means of air tablet and fix it in this

  state modified by cooling The disadvantage of this

  however, that such flexible hoses

  shrinkable materials made of thermoplastic materials, for example

  polyvinyl chloride, are not sufficiently resistant

  temperature for current needs, and that,

  moreover, they do not present the "memory of form" elastically

  desired, that is to say that, during a narrowing

  subsequently, they do not resume in all their de-

24-

tails their original form.

  Also known under the trade name

  "Thermofit", a backup technique for the manufacture of

  heat-shrinkable products, in which

  a high density polyolefin material is used

  for the injection molding of shaped parts

  these are then subjected to an electronic radiation of

  high intensity, so that a structure is obtained

  mesh three-dimensional cross-linked molecules

  gets a piece of shape that has a good

  mechanical resistance, is free from creep, does not tear, and has an elastic "shape memory"

  example, a shrinkable flexible hose treated with this

  is stretched over an object to be covered, it retracts during a short heating above the melting point of crystallization (in the case cited above 13500 C)

  and quickly returns to its original form and dimension

  gine, continuing a good assembly overlay

mechanical resistance.

  For the process described above, it is possible

  sible to use various basic polymers, even

  modified, according to any special conditions.

  However, it is necessary in each case

  radiation treatment is carried out before the draft

  che is enlarged or stretched when heated.

  Another possibility is to use, com-

  basic materials for shrinkable articles, polymers which, after the grafting of crosslinking auxiliaries, such as organosilanes, are crosslinked under the action of moisture, before or after the forming of the blank II is further important then that the action

  humidity is ensured by means of a special installation

  it has already been produced in the mold by the amounts of moisture inherent in the polymers and the adducts, or can be obtained

  by simple deposit under the influence of the environment.

  This proposal is based on the consideration that, unlike the periodic crosslinking operation, which has been known for a long time, and which is put into play, for example, in the cable manufacturing technique, under the influence

  of heat, by the grafting of low-weight compounds

  lecular, capable of reaction, for example

  silanes, as auxiliaries for cross-linking on macro-

  molecules of basic materials, which, in turn, con-

  secondary reactions to a polyfunctional chain link,

  "beam type" crosslinking, in which case more

  macromolecules are fixed together in

  a crosslinking node This chemical mechanism of

  lation results in significant link forces

  in the molecular domain, which are

  dissolved during heating in the thermoplastic state.

  tick and thus allow an enlargement, for example

  draft, after reheating and then

  fast cipping with resumption of their original form.

  So-called shrinkable articles manufactured in

  from such materials therefore have a "me-

  moire elastic shape "and are thus suitable for

  employment opportunities, for example as hoses and

  stanchions, in particular for sealing the pressure-tightness and humidity of the ends of electric cables, or as cuffs, in one or more parts, for the protection of connection or connection connections

  electric cables or also of tubular cables

  Properties relative to narrowing items

  Radiation-crosslinked sands are not modified or only negligibly, but the

  manufacturing is significantly simplified.

  Regardless of the type of base material, 4.- or the crosslinking technique used, which may also be a chemical crosslinking with peroxides, however, until now, difficulties have always been encountered. for example, during the production of flexible shrinkable tubes, also shrink-shaped parts of short length, during the expansion of the blank, for example by blowing,

  part of its "axial length" is converted into "lon-

  radial effect "The final consequence is that such a pipe

  is shortened by the axial portion taken by the expan-

  radial expansion during the shrinkage process

  The exact length of the pipe is therefore difficult to respect. The object of the present invention is to provide shrink-shaped parts, in particular flexible hoses or cuffs, which guarantee a precision

  dimensions, that is to say which do not undergo

  axial curvature as they shrink.

  For this purpose, the shrinkable part conforms to

  the invention is characterized by larger elements

  resistance to elongation, extending in a

  which are distributed around the perimeter in the

  The result is that during an enlargement

  radial, for example by blowing, the conversion of "long-

  axially "in" radial length "as it

  at present, is prevented, and therefore has not

  no more adverse effects during an ulterior shrinkage.

  The shrink-shaped parts conform to

  the invention are thus of precise dimensions, without reduction

  their length during shrinkage.

  It is already known (DB P 2 344 577) to strengthen

  the envelope of electric cables by inserting ele-

  The aim is, in this case,

  for elongated products of great length, of addicted -

  to be the mechanical strength in order to achieve, of this 5.-

  way, aerial cables of the so-called self-supporting type.

  During the suspension of these cables between the pyldnes, the tensile forces produced are absorbed by the endless resistant elements inserted in the cable and the driver is relieved of these tensile forces. On the other hand, the invention starts from the fact that the elements introduced in advance in the wall of the blank

  of short length are used to cancel the possibility of

  the displacement of the shrinkable material

  during the widening operation of the sketch.

  while, in a relatively surprising manner, the possibility of movement, for example of the polymeric substance, in the radial direction remains unchanged.

  measures provided for by the invention, in addition, for

  crease resistance to long tensile elongation

  tudinal of the finished product, here a shrink-shaped piece

  sand, the creep of the material during the expansion of

  the blank is directed only in the desired direction.

  According to another characteristic of the invention

  tensile elements consist of fibers inserted individually or in groups in the wall They may be, for example, fiber-based

  glass or polyamide, such as those known in the art.

  that commercial "Kevlar" These elements, for example in cor-

  mass donations or bundles of individual cords

  wired or strung duels may be further covered

  and / or impregnated with an adhesive product The mechanical connection

  of polymeric material can thus be increased by obtaining

  addition, a compact effect in the case of

  individual donations bundled together.

  The wall of the shrink-shaped part can be made in individual layers, which can themselves consist of different materials The elements with increased tensile strength are then inserted into

  one of the layers or between two neighboring layers.

  6. It has been found advantageous to form the wall of the piece of shrinkable shape in a material

  unitary complex with a single layer, the elements to resist

  increased tensile strength then being incorporated in the polymeric material It is preferable to set up these

  elements with high tensile strength in the ex-

  of the wall, and this in cases where, for reasons of choice of material, or of employment purposes, account must be taken of an increased tapping effect on the

shrinkable piece.

  In known cables provided with elements of

  so-called "wavy" tensile discharge in the outer shell

  the ripple of these elements should serve to ensure

  a force-transmitting link as intimate as possible between the traction and

  the envelope material (DDR patent 124 162) in order to

  read the elements themselves as traction devices.

  On the other hand, for the present invention, it is essential that the axial length of the elements with increased tensile strength correspond to the axial length of the

  the piece of shrinkable shape before enlargement.

  It is thus ensured that, in the case of a cour-

  length of the shrinkable pieces, it will not be influenced by an increased length of the ripples but

  that the elements actually fulfill their role of

  an axial shrinkage of the workpiece The known "waving" of the tension-relieving elements influence

  on the other hand, the "longitudinal rigidity" of the elements.

  For the manufacture of shaped parts

  cissables according to the invention, in the case of

  these with two open ends, such as

  In a preferred embodiment, it is advantageous first of all to extrude an endless pipe or flexible pipe into a material capable of crosslinking and, during this extrusion, the elements with increased tensile strength 7 are inserted concentrically in the wall

  of this pipe The shrink-shaped parts are de-

  cut to the desired lengths in this endless hose,

  before or after crosslinking

  rationing of drafts, with the assurance that

  in the wall of each of the parts, the elements

  increased tensile strength are inserted in axial lengths

the necessary ones.

  According to another characteristic of the invention, when the wall of the shrink-shaped parts is of the multilayer type, the elements with resistance

  increased traction, especially in the case of extrusion

  individual layers, are inserted in the last

  outer layer, during the same operation.

  The crosslinking of the sketches, endless flexible hose or also pipe already cut to desired length, can

  be carried out by the usual method. The chemical crosslinking

  that appropriate peroxides are also available.

  as well as crosslinking by implementing a

radiation rich in energy.

  Another possibility is cross-linking

  by the action of moisture For this it was noted

  it is advantageous to undertake the crosslinking of

  roughing during a moisture action at temperatures

  between 80 and 200 ° C., preferably between 140 and 18000. Enlargement in the state to be blocked

  then proceed directly to the next

  hot core In the case in which, according to another

  characteristic of the invention, the cross-linking reaction

  is produced by itself by the forming or injection operation of the blank, it is possible to

  special treatment with high temperature humidity.

  The increase in temperature before the expansion of the

  can be carried out independently of the moisture treatment, that is, in the case of mixtures capable of

  of microwave absorption, by a heating by energy

  high frequency The economics of the manufacturing process

tion can be improved.

  As already practiced for the crosslinking by the moisture of cables, the actual crosslinking can take place in a kind of sauna,

  that is to say in an atmosphere of water vapor at tempera-

  However, for the application of the invention for the same purpose, it is possible to use a mixture of glycerine and water or oil and water. This has the advantage, on the one hand, of regular conditions of temperature without special control measures and, on the other hand, the advantage that, by the components better compatible than water with the polymers of the shrinkable article, a faster diffusion penetration of the small amounts of necessary for cross-linking.

  basis, can be used all polymers, with-

  which an insertion of organo-silanes is possible by grafting

fage of initiator radicals.

  For reasons of ease of treatment, it has been found particularly advantageous for

  purposes of the invention and regardless of the mode of cross-linking.

  chosen, the use of polyethylenes and poly-

  mixtures of ethylene with vinylaceous monomers

  However, it is also possible to use

  as basic materials, rubber-based compounds

  rubber-propylene-ethylene alone or in combination with polypropylenes.

  For good resistance to ultraviolet radiation

  violet and also to improve the mechanical properties

  the rheology of the mixture during the production of the blank, it has been found advantageous to add carbon black to the base material. The most advantageous

  in this sense are carbon blacks from acetylene to pro-

  Non-hygroscopic properties These carbon blacks have 9._

  in addition, a high conductive capacity

  quantities, for example of the order of 1.5 to 3 per cent

  of polymer, to give the shrinkable article the

  The use of non-hygroscopic acetylene carbon black is of great importance, particularly in the case where the blanks are crosslinked by the action of moisture, after grafting.

  of silanes on the base material.

  If among the possible modes of crosslinking we wish to operate a crosslinking by humanity, it is

  Moreover, it is essential that the cross-linking

  such as organosilane, be available in quantities

  sufficient, but balanced with respect to the peroxide,

  in order to produce the molecular binding forces required

  for the shrinkage back from an expanded state The molar ratio between peroxides producing radical locations on the macro molecule and the

  the amount of silane added is advantageously

according to the invention, at 1/10.

  The invention is explained below with reference to

  FIGS. 1 and 2, showing parts

performed according to the invention.

  The elongated blank made of sus-

  crosslinkable, for example from a crosslinked endless flexible pipe, is designated by the reference 1 in Figure 1 In the wall of this pipe 2, are arranged

  elements 3 having a high resistance to trac-

  In the example shown, these elements consist of individual fiberglass-bundled wires 4. As shown in the figure, the elements 3 extend straight in the direction of the fiberglass.

  axially, the axial lengths of the blank and the

  ments 3 being therefore identical, the elements 3

  arranged around the pipe, their names

  here being equal to four, but to be chosen more than 10.-

  or lower depending on the requirements for the finished product.

  As a variant with respect to FIG.

  FIG. 2 shows a blank 1 already enlarged or in the gon-

  blow molded, that is to say, it has the shape of the ready-to-use shrinkable part which is locked in

  enlarged or enlarged state Bore 5 is increased by

  port to that of Figure 1, while the thickness of the

  tubular wall 2 is reduced in correspondence with the

  Increasing the diameter of the bore 5 The axial length

  is determined by elements 3, that is to say that it

  unchanged under the effect of the radial deformation operation according to the invention This has the consequence that

  the subsequent shrinkage process will also take place

  exclusively in the radial direction, while the

  length of the piece 1 remains unchanged A great deal

  dimensional dimension is thus ensured.

  As shown in Figure 2, the elements 3 have a different cross-sectional shape caused by the presence of multi-strand fibers, which means during the process of expanding the workpiece

  forces that provoked in earlier solutions

  These forces are now, according to the invention, absorbed by the elements 3, which allow

  a creep of the material in a radial direction, but which

  pose a change in axial length during the

  process of enlarging the room.

11 -

REVE N D I C A T IO N S

  1. Shape capable of shrinkage, of short length, such as cap, hose or

  shrinkable cuff made of extruded material and

  characterized in that, in the wall (2) are arranged, extending longitudinally, and distributed around the periphery, elements (3) having a higher tensile strength and an elongation

more reduced.

  2 Part according to claim 1, characterized

  characterized in that the elements (3) are fibers indicative of

  viduels or grouped together, inserted into the wall (2).

  3. Part according to one of claims 1

  or 2, characterized in that the wall (2) is constituted

in several layers.

  4. Part according to any one of the

  1 to 3, characterized in that the elements (3) are covered and / or impregnated with an adhesive product of

maintenance.

  5. Part according to any one of the

* dications 1 to 4, characterized in that the elements (3)

  with higher tensile strength and lower

  are arranged in the outer phase of the

  king with several layers of the piece (1).

  6. Part according to any one of the

  1 to 5, characterized in that the axial length

  the elements (3) essentially correspond to the length

  axial width of the shrinkable piece (1) before

its enlargement.

  7. Process for the manufacture of a piece of

  shrinkable form according to any one of the claims

  1 to 6, with two open ends, such as

  flexible yau, cuff or the like, characterized in that first extruded an endless hose or hose 12.- flexible material previously crosslinked, and, during

  extrusion, we introduce the elements (3), with high resistance

  tensile strength and low elongation, in

  concentric to the axis of the pipe, which remain inserted into the wall (2) of the extruded pipe, and cut in this pipe, the shrink-shaped pieces of appropriate lengths.

  8. Process for manufacturing shrinking parts

  sands according to any one of claims 1

  to 6, in a variant of the method according to claim 7, characterized in that, after extrusion of one or more wall layers, the elements (3) are inserted into the

  last outer layer of the wall.

  9. Process according to one of the claims

  7 or 8, characterized in that the endless blank obtained

  is reticulated under the action of high energy radiation.

ogy.

  10. Process according to one of the claims

  7 or 8, characterized in that the endless blanks ex-

  are cured by moisture treatment at a

  high temperatures between 80 and 200 00, especially

  between 140 and 18000 C, and are subject to

  warm core, to widen them to the stabilized state

of the room.

  11 Process according to any one of

  claims 7 to 10, characterized in that, as

  with high tensile strength and low

  fiber-based elements are used.

  12. Process according to any one of

  claims 7 to 11, characterized in that, as

  As the basic material for shrink-shaped parts, polyethylenes or ethylene polymer blends are used. 13. Process according to any one of

  claims 7 to 12, characterized in that, as

252047?

13.-

  base material, rubber-based compounds are used.

  rubber-ethylene-propylene alone or in combination with

  polyolefins, such as polypropylene.