IL31818A - Articles comprising a metal part and a polyolefin part,and process for their manufacture - Google Patents

Description

COMPRISING A A AMD PROCESS FOR CAOUTCHOUC 2 Λ Polyolefins have a number of properties owing to which they would be desirable coating substances in many cases they could be bonded to metals or other materials by simple and inexpensive Among these properties there may be mentioned their low coefficient of their high chemical resistance owing to which they do or undergo and their good resistance to the methods used or proposed up to now in order to bond them to metals are expensive and difficult to ί perform on a commercial scale and they do frequently not provide adhesion to allow the of which some surface is coated with the to be subjected to stringent ditions of For this polyolefins are bonded to metals certain particular cases and in these cases the bonding is mostly effected by riveting or after a treatment of the metal surface allows the polyolefin to become anchored One of the objects of this invention is to provide a simple and inexpensive method which can be used on a commercial scale in order to bond polyolefins firmly to metals and generally to all materials which can be coated with The invention also concerns those new articles factured by the method of this in connection with which this method can be applied in an especially advantageous invention in a method of bonding polyolefin to a metal or any other material to which rubber can be wherein vulcanizable rubber mixture is applied to the metal or the a polyolefin having a low melt index is applied to the rubber and the is subjected to a temperature of at least and a pressure of at least 2 The polyolefln having a low index may be coated itself with a polyolefln having a higher melt index since the adhesion between the different kinds of polyolefln is natural and occurs under the conditions of temperature and pressure of the method according to the connection with this invention the term means a polymer or a copolymer of one or several in which each monomer has not more than 4 carbon as well as mixtures of such polymers or The of low melt means pol of the kind defined above whose melt determined in ance with the standard 1238 57 modified by a mentary load of is equal to or below term rubber means any mixture which contains one or several natural or synthetic rubbers and undergoes vulcanization under the aforesaid ture and which can be bonded to The materials such as the metal to which the olefln is to be bonded if be pretreated in any conventional manner which does not form part of with a view to facilitating the adhesion of the vulcaniaable rubber mixture Such treatments are well For metals they consist as a rule in a surface such as the deposition of copper or of a special bonding Since the adhesion between the polyole and the rubber mixture is as a rule whatever the rubber or rubbers used in the it as rule preferable to select the rubber or rubbers in accordance with their adhesiveness to the material to w ich the pol olefin is to be The layer of rubber mixture interposed between the material and the polyole shall as a rule a thickness of at least about layer can be produced by any suitable method which does not part of the present For it may be constituted by a preformed rubber In a embodiment of the invention the rubber layer has a thickness which is sufficient to impart to the final article the desired mechanical properties as as they depend on the existence and quality of this rubber The layer of polyolef n of low melt index bonded to the metal o other material by means f a vuleanizable rubber mixture as bonding agent depending on its ness and the chosen manufacturing be produced by depositing a powder or a suspension in a or by superimposing a preshaped It is frequently desirable that the polyolefin which covers the metal or other material has the possible resistance to Since this resistance is higher in polyolefins of high molecular those having a low melt it is preferred in these cases not to cover the polyolefin of low melt ia imposed to the rubber with another polyolefin having a higher melt In Other especially where the resistance to abrasion need not necessarily be the highest the layer of polyole n of melt index may be coated with another layer of pol of higher melt The layer of of low melt index has in that case only the tion of forming a bond between the adhesive rubber mixture and the pol olefin layer of higher melt makes it possible to as a bonding a rubber mixture even in cases where it is desired to the ties of polyolefins of relatively high melt which do not adhere to the pol having a low melt index are inconvenient to work and they can as a rule be worked under particular conditions and with special tools It frequently preferred to constitute the outer part from a polyolefin of relatively elevated melt index which is easy to and to bond it to the rubber laye by a thin layer of polyolefin of low melt which can be fo by the disposition of a powder or by applying a suspension or a In a general manner the layer of polyolefin of low melt which covers the rubber may itself be coated with a material adhering to fhis may a different kind of rubber which is known not to adhere well to the In this case the bonding agent this second kind of rubber and the metal is constituted by the layer of rubber which is bonded to the and the of polyolefin of lo melt This arrangement makes it for to bond rubbers to metals under frequently very advantageous The invention will be described in more detail below with the aid of examples to which it is not It will be noted that some of the examples concern the manufacture of new industrial articles which can readily be made by the method according to the The first example concerns manufacture of an internal sliding joint which is diagrammatically in the accompanying drawing in 1 is a longitudinal section through the 2 is a section through the mould used for its Joints of this kind have an inner sliding sleeve made rom a material which possesses and retains all the time as low a coefficient of friction as possible and which must also be resistant to corrosion and such as polyethylene of low melt index are especially suitable for this use but they could up to now not be utilized for this The invention makes it possible to manufacture in a simple manner such a sliding joint inner sliding sleeve consists of a of low melt These joints are new industrial sleeve 2 is coaxial with the sleeve consists of pressure polyethylene of specific gravity and melt index the one known by the trademark Between the sleeves 1 and 2 a rubber layer 3 is In joints known up to now the rubber layer had merely the function of imparting to the joint certain desired mechanical properties and it been necessary to subject the inner sleeve to certain treatments in orde to bond it to the In contrast in the joint according to the the rubber layer 3 has not only the function of imparting to the joint the desired mechanical but it serves to bond the outer sleeve 1 to the inner sleeve and this manner of bonding the sleeves does not make it necessary to subject the inner sleeve of polyethylene of low melt index to any particular Such a sliding joint can readil manufactured by by means of a mould like the one illustrated in which comprises a cylindrical and a central cylindrical core 5 coaxial with the wall The outer metal sleeve 1 is placed into the between the wall 4 and core 5 immediately adjacen the wall 4 and the inner 2 surrounds the core metal sleeve 1 may have undergone any riate conventional which does not form part of the with a view to improving its adhesion to the rubber layer inner sleeve has been froa the known polyethylene brand marketed under the trademark Hostalen T e 3 is by between sleeve 1 and the sleeve It is for of the following rubber by weight natural rubber 100 carbon black 55 plasticizer 5 stearic acid 1 zinc oxide 5 2 sulfur benzothiazole 1 Any suitable conventional plasticizer and oxidant may be For the plasticizer may be an oily petroleum such as the one commercially known as The may for The pressure in the interior of the mould is about 25 and for effecting vulcanization the whole if desired after a is heated to for 15 After demoulding one obtains the joint shown in The adhesion between the inner sleeve of polyethylene and the rubber layer is firmer than that existing between the outer metal sleeve and the rubber In orde to improve the resistance of the lene sleev to flowing it may be This can be for by means of a glass fiber or glass fibers may be distributed through the mass in the same manner as is done with fibers in rubber mixes of the kind known as The presence of the glass fibers within the mass of polyethylene of low melt index does not affect the adhesion of the latter to the The second example concerns the manufacture of metal It is known that skis of this type are usually constituted by metal as a rule of a light metal such as aluminium or an aluminium coated with a gliding surface of polyethylene of low melt index which is used because of its favourable coefficient of gliding and its high resistance to Hitherto not been possible to secure the gliding sheet to the metal sole except by using complicated processes which are difficult to operate on a commercial scale and do not even produce finished articles of uniform The method according to the invention overcomes the difficulty of securing the polyolefin layer to the metal sole in a particularly advantageous To the metal which is preferably in a known manner in order to improve the adhesion of the a film a vulcanizable rubber mixture and a sheet of polyolefin of low melt index are The assembly is subjected to the conditions of pressure and temperature conducive to the vulcanization of the For the metal sole is coated with a prepared by calendering of the following Parts weight natural rubber 100 carbon black 45 zinc oxide 2 stearic acid 2 oil 2 Santocure designation of sulfenamide vulcanising agent sulfur The gliding consisting of a thick sheet of polyethylene of the type known by the trademark Hostalen is applied to the rubber The assembly is placed in an appropriate A pressure of 5 rcm 2 is applied and the temperature is maintained at for 20 T e ski is then withdrawn from the Skis of this kind can be made more resilient by an increased thickness of the rubber layer interposed between the metal sole of the gliding it has been found that this design imparts to the skis properties at least as advantageous and even more advantageous those of the known skis in which the rubber layer has been disposed on the upper part of the manufacturing skis of this type a metal sole is coated with an adhesive rubber layer of a thickness to give the ski the desired For the may be carried ou described above but the film used has a thickness of 2 mm instead of method according to the invention is not fined to the manufacture of new commercial articles but can generally be applied in all cases where it is desired to bond a polyolefin to materials like metals to which rubber can be for metal vessels may thus be lined for protection against the edges of aircraft wings and of helicopter blades may be coated for protection against The third example shows how of polyolefin of low mel index can itself be coated with another material adhering to this A plate is in an known by the successive application of the rubber adhesives known by the trademarks 211 and Chemosil with a view to adhere to a vulcanizable rubber mixture of the following Parte weight natural rubber 100 carbon black 71 zinc oxide 5 stearic acid 1 plasticiaer 5 sulfur disulfide the steel plate there is applied a sheet of the aforesaid mixture and a sheet of polyethylene known the trademark Hostalen having a melt index The layer of rubber mixture and the polyethylene film are each To the sheet of polyethylene Hostalen of low melt index there is applied a 5 thick plate of polyethylene of the kind known under the commercial designation having a melt index of The assembly is introduced into a press and kept at a temperature of and a pressure of 5 kg em2 for 15 Xn the article thus made the sheet of polyethylene of low melt index adheres so firmly to the steel plate tha in tearing tests it is found that ultimately the intermediate the layer of rubber ruptures but it is never detached layers of the On a similar steel similarly there is disposed a similar rubber sheet and a similar film of polyethylene Hostalen the latter there is applied a 5 thick rubber sheet of the following farts weight synthetic 100 propylene copolymer rubber 10 carbon black SAP 60 butyl peroxide sulfur Th is kept at a temperature of and under a pressure of 5 for 15 copolymer rubber sheet is formly bonded to steel plate from which it cannot be other uses of the invention there ma be cited the lining of metal vessels or vats with a view to protecting them from corrosion and attack by the stances contained S method according to the invention can be used in order to make adhere to the polyolefin any material which canno be made to adhere to the where it is desired to reinforce a polyolefin product with a reinforcement the latter will be made adherable to rubber and be coated with a thin layer of a vulcanizable rubber a glass fiber fabric which has been made adherable to rubber by the will coated by calendering with a thin layer of a mixture having the following compositions Parts weight natural rubber 100 carbon black 35 10 stearic acid zinc oxide 5 2 sulfur tetraethylthiuram disulfide This reinforcement can now be used reinforcing the inner part of the slidin sleeve of polyolefin of low melt described adhesion between the fabric and the is in the tearing test th rupture occurs in the bond between the glass fiber fabric and the rubber In the same any synthetic or metallic fabric can be made to olefin and can thus be used as a reinforcement of or parts of articles of pol insufficientOCRQuality

Claims (8)

318181/2 - 15 - Claims

1. Articles comprising at least one part of metal or an other material to which rubber can be bonded, coated with a polyolefin, wherein the polyolefin is bonded to the metal or other material by a layer of vulcanized rubber.

2. Articles according to Claim 1, wherein the polyolefin bonded to the metal or other material has a melt index below 0.15. I

3. Articles according to Claim 1, wherein the polyolefin constituent includes a part of polyolefin of iL'ow melt index bonded to the rubber, and a part of polyolefin of higher melt index superimposed on the former part of polyolefin.

4. Articles according to any of Claims 1 to 3» wherein the rubber layer is made so thick that it imparts to the article the desired mechanical properties to the extent that these depend on_ the pressure and quality of the rubber layer.

5. Articles according to Claim 4, being sliding joints in which the inner sleeve consists of polyolefin of low melt index.

6. Sliding joints according to Claim t wherein the inner sleeve comprises a reinforcement,

7. Articles according to Claim 3» wherein the part of polyolefin of low melt index is covered with a layer of an ethylene-propylene copolymer. 31818/¾ ·— 16 v

8* A method of inding a polyolefin of comparatively high melt index to metal or any another material to which rubber can be bonded* wherein a layer of rubber is made to adhere to the metal orother material, a laye of polyolefin of lo¾ melt index is placed on the rubber layer, and a layer of polyolefin of comparatively high melt index ie placed in the former polyolefin layer, and the assembly Is subjected to a temperature of o ' 2 at least 1400» and a pressure of at least 2 kg/em ·