CA1190365A - Process for the production of a blank for containers and blank produced by the process - Google Patents
Process for the production of a blank for containers and blank produced by the processInfo
- Publication number
- CA1190365A CA1190365A CA000352909A CA352909A CA1190365A CA 1190365 A CA1190365 A CA 1190365A CA 000352909 A CA000352909 A CA 000352909A CA 352909 A CA352909 A CA 352909A CA 1190365 A CA1190365 A CA 1190365A
- Authority
- CA
- Canada
- Prior art keywords
- moulding
- tubular
- mouth part
- crystallinity
- neck sections
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
- B29C2949/00—Indexing scheme relating to blow-moulding
- B29C2949/07—Preforms or parisons characterised by their configuration
- B29C2949/0861—Other specified values, e.g. values or ranges
- B29C2949/0862—Crystallinity
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
- B29C2949/00—Indexing scheme relating to blow-moulding
- B29C2949/07—Preforms or parisons characterised by their configuration
- B29C2949/0861—Other specified values, e.g. values or ranges
- B29C2949/0862—Crystallinity
- B29C2949/0863—Crystallinity at the neck portion
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29L—INDEXING SCHEME ASSOCIATED WITH SUBCLASS B29C, RELATING TO PARTICULAR ARTICLES
- B29L2001/00—Articles provided with screw threads
Landscapes
- Blow-Moulding Or Thermoforming Of Plastics Or The Like (AREA)
Abstract
ABSTRACT
The invention relates to a tubular pre-moulding of a thermoplastic, suitable for subsequent shaping to give containers by a blow moulding process, and to a process and equipment for producing the pre-moulding.
In a tube, future mouth parts and parts of adjacent neck sections are moulded to pre-mouldings, preferably from two blank parts joined to one another, by an axial stretch process and a blow-moulding process, the parts in the transition between the two mouth parts being severed in order to form two separate blank parts.
A tubular pre-moulding is produced after closing one end of the particular blank part and, if necessary, reworking in order to obtain the requisite closing face at the other end.
The invention relates to a tubular pre-moulding of a thermoplastic, suitable for subsequent shaping to give containers by a blow moulding process, and to a process and equipment for producing the pre-moulding.
In a tube, future mouth parts and parts of adjacent neck sections are moulded to pre-mouldings, preferably from two blank parts joined to one another, by an axial stretch process and a blow-moulding process, the parts in the transition between the two mouth parts being severed in order to form two separate blank parts.
A tubular pre-moulding is produced after closing one end of the particular blank part and, if necessary, reworking in order to obtain the requisite closing face at the other end.
Description
PLM ABj Malm~ PP 513 Proce~s ~or the production of a b:Lank for containers and blank produced by the process.
The inYention relates to a tubular pre-moulding of a thermoplastic, suit~ble ~or subsequent shaping to give containers by a blow-moulding process9 and to a process and e~uipment for producing the pre-moulding.
~ a tube, ~uture mouth parts and parts of adjacent neck sections are moulded to pre-mouldings, from two blank parts ~oined to one ano-ther~ by an axial stretch process and a blow-mouldi~g process, the parts in the transition between the two mouth parts being severed in order.to form two separate blank parts which3 after closing at one o~ the ends and subsequent reworking to produce the requisite closi~g sur~aces at the respective ~ther ends, ~5 each alone ~orm a tubular pre-moulding.
: In a production process used for the manufacture o~ containers from a thermoplastic, blanks normally called pre-mouldings for containers are produced ~rom severed parts o~ extruded long tubes o~ an ~morphous thermoplastic. At one end, -the severed piec~s are shaped in such a way that they form the future mouth part .
of the container, whils-t they are closed ~t the opposite end.
- - -The present invention eliminates certain-dis-ad-vantages co!nnected with the production process indicated above, acco:rding to the known technologyO
:
3~6~i -- 2 ~
The inven-tion is sui-table especially for the manufacture of containers from a thermoplas-tic of the polyester or polyamide type. Exarnp]es of such materials are polyethylene -terephthala-te, polyhexamethylene-adipamide~ polycaprolactam 7 polyhexamethylene-sebacamide, polyethylene 2,6- and 1,5-naphthalate, polytetramethylene 1,2-dihydroxybenzoate and copolymers of ethylene terephthalate, ethylene isophthalate and similar polymers. The description of the inv2ntion below relates mainly to polyethylene terephthalate~ called PET in the further text1 but -the invention is not restricted only to the use of either this material or ~ne of the other materials already mentioned; instead, it is also applicable to many other thermoplastics.
For a be-tter understanding of the existing problem and of the invention, several characteristic properties of the polyester polyethylene terephthalate are described below. From the literature, for example Properties of Polymers, by D.~. van Krevelen, ~lsevier Scienti~ic Publishing Company, 19765 it is known that the properties of the material change when amorphous poly-ethylene terephthalate is oriented. Some of these changes are shown in the dîagrams, ~igures 14.3 and 14.4 on pages 317 and 319 in the book "Properties of Polymers".
The symbols used in the discussion below correspond to the symbols in the said book.
PET, like many other thermoplas-tics, can ~e oriented ~by stretching the material. Normally this ~ ~ .
.. . .
stretching takes place at a temperature above the glass ~ransition temperature Tg of -the material~ The strength properties of the material are improved by orienting. The literature shows that, in the case of -~le thermoplastic PET~ an increase in the stretching ratio ~9 that is to say the quotient of the length of the stretshed material and -the length of the unstretched material? also leads to an increase in the improvement o~ the material properties. When the stretching ratio J~ is increased from about 2 to a little ~ore than 3~
particularly large changes in the material properties are obtained. The strength in the direction of orien-tation is here markedly improved, whilst at the same time the density ~ and likewlse the crys~tallinity Xc rises and the glass transition temperature Tg is raised. It can be seen ~rom the diagram on page 317 that, after stretch-inglwith~ assuming the value of 3.1, the material with-stands a force per unit area, which corresponds to ~ - 10 coupled ~ith a very small elongation, whilst the elonga-tion atJ~_ 2.8 is substantially larger. In the further text, the term "step" is sometimes used to designate orlenting ~hich is obtained by stretching, or a reduction in thickness by about 3 times~
and which leads to the marked improvements o~ the material properties, indicated above.
The diagrams quoted above show changes which are obtained on mono-axial orientation o~ the material.
In biaxial orientation, similar effects are obtained in both directions of orien-tation. Orientation is carried out as a rule by successive stretchings.
Improved material properties, corresponding to those which are obtained by the "stepl' defined above, are also obtained if an amorphous material is st~etched until i~ flows and, before flo~ing, the material is at a tem perature which is below the glass transition -tempera ~re Tg~ In a rod being drawn~ a reduction of the diameter o~ about ~ times results in the flow zone . On drawing, the flow zone is continuously displaced into -the amorphous material/ whilst at the same time the material, which has already undergone the state of flowing, absorbs the tensile forces of the test rod w;thout an additional permanent stretching.
For bottles, defined external diameters of the mouth with the associated thread are standardised and9 in the technology known at present when using the moulding process described as an introduction, this determines the greatest diameter which is permissible in the blow-moulded container body~ The reasons for this are explained in more detail in the following text. ' In order to obtain an arnorphous starting material for the pieces o~ tube, which are to be shaped into pre mouldings, the material must be cooled rapidly to below the glass transition temperature Tg af-ter extruding - in the case of extruded tubes from which the pieces of tube are severed. In'the case of excessive wall thickness, the materia'l does not possess adequate heat conductivity to ' ~3~3 enable the central sec-tions of -the wall to be cooled as rapidly as required, so that the material located in the centre becomes crystalline and opaque. For this reason, viewed theoretically, the largest possible wall thickness of the extruded tubes is less than about 9 mm.
In practice, however, wall thicknesses of less than 4 mm are used as a rule. In fact, in blow-moulding of a pre-moulding having wall material of excessive thickress9 problems arise due to the cooling of the material during the actual blow-moulding step and before the material reaches the wall of the mould. The blow-moulded con-tainer is no longer clear as glass and, instead, contains opaque ~hite sections. In blow-moulding, in order to obtain containers having the requisite resistance against -stresses and penetratlon of the container wall, the wall thickness of the finished container must not fall below a defined value. Moreover, a reduction of the~external diameter of the tube during the shaping of the mouth part of the pre-moulding is not possible in accordance with -known technology. The result is that the desired mouth diameter of the blow-moulded container is decisive for the diameter of the pre-moulding and thus for the maximum diameter of the blow-moulded container body.
If bottles of large capacity are required, these bottles are extended, according to known technology, in the axial direction after they have reached the maximum possible diameter.--- In additiQn to the disadvantage of a certain instability, the extension represents an unsatisfactory utilisation of the quantity of material in he container ' body since the requisite quantity of ma-terial per unit volume of storage capacity is greater than would be necessary if both -the diameter and the length of the container body were adapted -to -the actual volume required.
Moreover, the unnecessarily large surface of the con-tainer leads to a corresponding increase in the overall penetration of carbon dioxide during the storage of beverages con-taining carbonic acid.
To utilise the ma-terial properties of -the material in the best way7 it is desirable tha-t the diame-ter of those parts of the pre-moulding which, after the blow-moulding step, represent the ac-tual container body, is given a value which has the result that the material in the blow-moulded container body assumes the desired orientation. In containers of PET it is desirable that the material, in conjunction with blow-moulding5 is biaxially stretched in such a way that the product o~ the stretchings is about 9.
The above shows that, according to kn~wn tech-nology, the quantity of material in the mouth part is not deter~ined by the calculated stresses but by the maximum --diameter of the container body. As a rule, this leads to a considerable excess of material in the mouth part.
~ or example, in a PET bottle of 1 litre capacity, the mouth part can, according to known -technology, contain up to 25-3()% of the -total quantity of ma-terial. Dis-regarding the~ unpleasant appearance of the oversizing of -the mouth part, this fact also results in a waste of ma-terial, which is of importance in the mass production .
3~
o~ articles.
In the technology applied at present, the mouth part and adjacent neck parts consist of unoriented material, that is to say amorphous material. This means that the material in the mouth part including the adjacent neck parts has properties which differ from those of the container body. In ~ontainers of, for example9 PET, the material in the mouth part has a glass transition temperature Tg of 71~C, whilst the glass transition temperature of the material in the container body is about 81C~ It follows from this that the material in the mouth part softens at a lower temperature than the material in the container body~
It is already known, by cold-forming of the mouth part of the blank, to displace material downwards from the mouth part into the sections of the blank, which later represent the wall sections of the container body~
In this way, a certain matching of the quantity of material in the mouth part to the future stresses is achieved but, between the actual container body and the mouth part, neck sections are formed in which the ma-terial is stretched by a factor of less than 3. These neck sections in the moulded container thus consist of inadequately oriented material, whilst at the same time the wall thickness is undesirably large. This method is also known from Canadian Application ~o. 322,499, filed February 28, 1979, inventor Kjell M. Jakobsen.
British Patent Specification 1,536,194 published December 20, 1978 to Carnaud Total Interplastic has dis-closed a method wherein a tubular blank9which is closed at one end and which is provided at the other end with .
beading for flxing the blank in a downstream blowing element, is injection-moulded and wherein the tubular blank is blow-moulded after a certain reshaping to give a container. Material in the tubular part of the blank is expanded in the radial direction at a temper-ature abo~e the ylass transition temperature Tg in or-der thus to form the mouth part of the container. A
container formed in the manner described possesses a mouth part and a neck section in which the material has been exposed to only very slight stretching and hence orienting, so that the disadvantages, already indica-ted~ with respect to the mouth part of the known con-tainers are also present in this container.
The invention described in British Patent Speci-fication 1,536,194 also has the disadvantage that only a part of the material content of the injection moulded tubular blank is utilised when reshaping the blank to give the finished container. It is obvious that the losses of material, which occur in this process, rep-resent an economic disadvantage in the mass production of articles~
From Federal German Offenlegungsschrift DOS
The inYention relates to a tubular pre-moulding of a thermoplastic, suit~ble ~or subsequent shaping to give containers by a blow-moulding process9 and to a process and e~uipment for producing the pre-moulding.
~ a tube, ~uture mouth parts and parts of adjacent neck sections are moulded to pre-mouldings, from two blank parts ~oined to one ano-ther~ by an axial stretch process and a blow-mouldi~g process, the parts in the transition between the two mouth parts being severed in order.to form two separate blank parts which3 after closing at one o~ the ends and subsequent reworking to produce the requisite closi~g sur~aces at the respective ~ther ends, ~5 each alone ~orm a tubular pre-moulding.
: In a production process used for the manufacture o~ containers from a thermoplastic, blanks normally called pre-mouldings for containers are produced ~rom severed parts o~ extruded long tubes o~ an ~morphous thermoplastic. At one end, -the severed piec~s are shaped in such a way that they form the future mouth part .
of the container, whils-t they are closed ~t the opposite end.
- - -The present invention eliminates certain-dis-ad-vantages co!nnected with the production process indicated above, acco:rding to the known technologyO
:
3~6~i -- 2 ~
The inven-tion is sui-table especially for the manufacture of containers from a thermoplas-tic of the polyester or polyamide type. Exarnp]es of such materials are polyethylene -terephthala-te, polyhexamethylene-adipamide~ polycaprolactam 7 polyhexamethylene-sebacamide, polyethylene 2,6- and 1,5-naphthalate, polytetramethylene 1,2-dihydroxybenzoate and copolymers of ethylene terephthalate, ethylene isophthalate and similar polymers. The description of the inv2ntion below relates mainly to polyethylene terephthalate~ called PET in the further text1 but -the invention is not restricted only to the use of either this material or ~ne of the other materials already mentioned; instead, it is also applicable to many other thermoplastics.
For a be-tter understanding of the existing problem and of the invention, several characteristic properties of the polyester polyethylene terephthalate are described below. From the literature, for example Properties of Polymers, by D.~. van Krevelen, ~lsevier Scienti~ic Publishing Company, 19765 it is known that the properties of the material change when amorphous poly-ethylene terephthalate is oriented. Some of these changes are shown in the dîagrams, ~igures 14.3 and 14.4 on pages 317 and 319 in the book "Properties of Polymers".
The symbols used in the discussion below correspond to the symbols in the said book.
PET, like many other thermoplas-tics, can ~e oriented ~by stretching the material. Normally this ~ ~ .
.. . .
stretching takes place at a temperature above the glass ~ransition temperature Tg of -the material~ The strength properties of the material are improved by orienting. The literature shows that, in the case of -~le thermoplastic PET~ an increase in the stretching ratio ~9 that is to say the quotient of the length of the stretshed material and -the length of the unstretched material? also leads to an increase in the improvement o~ the material properties. When the stretching ratio J~ is increased from about 2 to a little ~ore than 3~
particularly large changes in the material properties are obtained. The strength in the direction of orien-tation is here markedly improved, whilst at the same time the density ~ and likewlse the crys~tallinity Xc rises and the glass transition temperature Tg is raised. It can be seen ~rom the diagram on page 317 that, after stretch-inglwith~ assuming the value of 3.1, the material with-stands a force per unit area, which corresponds to ~ - 10 coupled ~ith a very small elongation, whilst the elonga-tion atJ~_ 2.8 is substantially larger. In the further text, the term "step" is sometimes used to designate orlenting ~hich is obtained by stretching, or a reduction in thickness by about 3 times~
and which leads to the marked improvements o~ the material properties, indicated above.
The diagrams quoted above show changes which are obtained on mono-axial orientation o~ the material.
In biaxial orientation, similar effects are obtained in both directions of orien-tation. Orientation is carried out as a rule by successive stretchings.
Improved material properties, corresponding to those which are obtained by the "stepl' defined above, are also obtained if an amorphous material is st~etched until i~ flows and, before flo~ing, the material is at a tem perature which is below the glass transition -tempera ~re Tg~ In a rod being drawn~ a reduction of the diameter o~ about ~ times results in the flow zone . On drawing, the flow zone is continuously displaced into -the amorphous material/ whilst at the same time the material, which has already undergone the state of flowing, absorbs the tensile forces of the test rod w;thout an additional permanent stretching.
For bottles, defined external diameters of the mouth with the associated thread are standardised and9 in the technology known at present when using the moulding process described as an introduction, this determines the greatest diameter which is permissible in the blow-moulded container body~ The reasons for this are explained in more detail in the following text. ' In order to obtain an arnorphous starting material for the pieces o~ tube, which are to be shaped into pre mouldings, the material must be cooled rapidly to below the glass transition temperature Tg af-ter extruding - in the case of extruded tubes from which the pieces of tube are severed. In'the case of excessive wall thickness, the materia'l does not possess adequate heat conductivity to ' ~3~3 enable the central sec-tions of -the wall to be cooled as rapidly as required, so that the material located in the centre becomes crystalline and opaque. For this reason, viewed theoretically, the largest possible wall thickness of the extruded tubes is less than about 9 mm.
In practice, however, wall thicknesses of less than 4 mm are used as a rule. In fact, in blow-moulding of a pre-moulding having wall material of excessive thickress9 problems arise due to the cooling of the material during the actual blow-moulding step and before the material reaches the wall of the mould. The blow-moulded con-tainer is no longer clear as glass and, instead, contains opaque ~hite sections. In blow-moulding, in order to obtain containers having the requisite resistance against -stresses and penetratlon of the container wall, the wall thickness of the finished container must not fall below a defined value. Moreover, a reduction of the~external diameter of the tube during the shaping of the mouth part of the pre-moulding is not possible in accordance with -known technology. The result is that the desired mouth diameter of the blow-moulded container is decisive for the diameter of the pre-moulding and thus for the maximum diameter of the blow-moulded container body.
If bottles of large capacity are required, these bottles are extended, according to known technology, in the axial direction after they have reached the maximum possible diameter.--- In additiQn to the disadvantage of a certain instability, the extension represents an unsatisfactory utilisation of the quantity of material in he container ' body since the requisite quantity of ma-terial per unit volume of storage capacity is greater than would be necessary if both -the diameter and the length of the container body were adapted -to -the actual volume required.
Moreover, the unnecessarily large surface of the con-tainer leads to a corresponding increase in the overall penetration of carbon dioxide during the storage of beverages con-taining carbonic acid.
To utilise the ma-terial properties of -the material in the best way7 it is desirable tha-t the diame-ter of those parts of the pre-moulding which, after the blow-moulding step, represent the ac-tual container body, is given a value which has the result that the material in the blow-moulded container body assumes the desired orientation. In containers of PET it is desirable that the material, in conjunction with blow-moulding5 is biaxially stretched in such a way that the product o~ the stretchings is about 9.
The above shows that, according to kn~wn tech-nology, the quantity of material in the mouth part is not deter~ined by the calculated stresses but by the maximum --diameter of the container body. As a rule, this leads to a considerable excess of material in the mouth part.
~ or example, in a PET bottle of 1 litre capacity, the mouth part can, according to known -technology, contain up to 25-3()% of the -total quantity of ma-terial. Dis-regarding the~ unpleasant appearance of the oversizing of -the mouth part, this fact also results in a waste of ma-terial, which is of importance in the mass production .
3~
o~ articles.
In the technology applied at present, the mouth part and adjacent neck parts consist of unoriented material, that is to say amorphous material. This means that the material in the mouth part including the adjacent neck parts has properties which differ from those of the container body. In ~ontainers of, for example9 PET, the material in the mouth part has a glass transition temperature Tg of 71~C, whilst the glass transition temperature of the material in the container body is about 81C~ It follows from this that the material in the mouth part softens at a lower temperature than the material in the container body~
It is already known, by cold-forming of the mouth part of the blank, to displace material downwards from the mouth part into the sections of the blank, which later represent the wall sections of the container body~
In this way, a certain matching of the quantity of material in the mouth part to the future stresses is achieved but, between the actual container body and the mouth part, neck sections are formed in which the ma-terial is stretched by a factor of less than 3. These neck sections in the moulded container thus consist of inadequately oriented material, whilst at the same time the wall thickness is undesirably large. This method is also known from Canadian Application ~o. 322,499, filed February 28, 1979, inventor Kjell M. Jakobsen.
British Patent Specification 1,536,194 published December 20, 1978 to Carnaud Total Interplastic has dis-closed a method wherein a tubular blank9which is closed at one end and which is provided at the other end with .
beading for flxing the blank in a downstream blowing element, is injection-moulded and wherein the tubular blank is blow-moulded after a certain reshaping to give a container. Material in the tubular part of the blank is expanded in the radial direction at a temper-ature abo~e the ylass transition temperature Tg in or-der thus to form the mouth part of the container. A
container formed in the manner described possesses a mouth part and a neck section in which the material has been exposed to only very slight stretching and hence orienting, so that the disadvantages, already indica-ted~ with respect to the mouth part of the known con-tainers are also present in this container.
The invention described in British Patent Speci-fication 1,536,194 also has the disadvantage that only a part of the material content of the injection moulded tubular blank is utilised when reshaping the blank to give the finished container. It is obvious that the losses of material, which occur in this process, rep-resent an economic disadvantage in the mass production of articles~
From Federal German Offenlegungsschrift DOS
2,540,930 published April 8 9 1976, a process is known wherein a tubular blank of PET is reshaped to give a ; container and wherein the container wall consists of a material which is stretched by a factor of, for example, more than 1.5. ~he bottom part of the container con-sists of an amorphous unoriented materi~l, whilst the neck sections of the container consist of material which has been oriented only to a slight extent. As a result of heatin~ and crystallisation, . ' : -caused thereby 9 the streng-th of -the material is impr3ved in the unoriented ~ones which at the same time become opaque. Furthermore~ a combination of the methods indicated above results in an undesired oversizing of the neck sectîons of the containers, whilst the latter at the same time have poorer propertles than the material in -the actual container body.
- The invention provides a blank which makes it possible that, in a container formed from the blank, both the mouth part and the neck sections and also the container body consis-t of a material which is adapted -to the occurring stresses and in which the material in the said parts is oriented to a satisfactory extent in such a way tha-t the material is stre-tched, at least in the axial direction, by a factor of more than 3.
This results in the advantage of a raised glass transition temperature Tg in all the said par1s of the container. This means that all the sai~ parts will have the same heat resistance, and this is a great advantage compared with containers which are formed according to the known technology and which, at least as far as con-tainers with mainly clear and transparent materials are concerned, have neck sections and mouth parts which-are more sensitive to heat stresses than the actual container body.
Moreover, the invention enables a container of sm~l~rmouth diameter to be manufactured, the length and diameter of the container body being matched to the storage capacity of the container in such a way that the L~)3~
-- 10 ~
smallest possible quantity of material per unit volume of storage space results.
In addition, the invention enables a cont.ainer of any desired shape of the n~ck part to be formed from the blank, the container material in the mouth part and in the neck part also being oriented and having a crystallinity of more than l~/ol this was achieved by stretching the material to the requisite extent, for example in the case of con-tai.ners of PET by stretching in the axial direction by a Eactor of more than 3. According to known technology it was hitherto not possible to obtain such a degree of orienting, unless the mouth part and neck sections of the containers wexe to consist of mainly unoriented material, in which case the neck sections merge in the shortest possible distance with oriented sections of the container body, where the wall thickness has been reduced by a factor of at least 3. This shaping represented an attem~t to reduce the size o~ that zone in the neck part, which has mainly amorphous material and low orientation and hence a low glass transition temperature Tg.
In accordance with one aspect of the invention, there is provided a tubular pre-moulding of a thermoplastic material, the pre moulding having a mouth part with adjacent neck sections at one end, a closure at the other end and a tubular section between the two ends, and the closed end and the tubular section of the pre-moulding consisting mainly of amorphous unoriented material having a crystallinity of less than 5%. The tubular pre-moulding of the invention i.s characterized in that the rnouth part with adjacent neck sections of the pre-moulding are oriented mainly in the axial direction of the pre-moulding by reducing the wall thickness by a factor corr@sponding to the reduction of th.ickness obtained in a sheet of the material monoaxially stretched into yielding, the crystal-linity of the material in the mouth part and in the adjacent neck sections being at most 5~/0~
According to a -further aspect of the invention, there is provided in a tubular pre-moulding of a thermo-plastic of polyester or polyamide type, the pre-moulding having substantially uniform initial thickness and comprising a mouth part with adjacent neck sections at one end, a closure at the other end and a tubular section between the two ends, the closed end and the tubular section of the pre-moulding consisting mainly of amorphous unoriented material having a crystallinity of less than 5%, the impro~e-ment wherein the mouth part o-f the pre-moulding, with adjacent neck sections, consists of material which is oriented substantially by a reduction in the thickness of the material while the remainder of the pre-moulding retains its original thickness and, at least in the mouth part, the material has a lower degree of orientation in the circum-ferential direction of the pre-moulding as compared to the axial direction. The crystallinity of the material in the mouth part ;;s at most 50/0, the orientation of the mouth ;' ~, , . . .
- lla -part and ad~acent neck sections of the pre-moulding by the thickness reduction providing an increased glass transition temperature Tg in the mouth part and neck sections which is suhstantially equal to the glass transition temperature of the tubular section when the amorphous material of the tubular section is oriented by a subsequent blowing of the pre~moulding to a container.
According to the invention, the tube of thermo-plastic material is clamped in between two mutually separate clamping devices. ~le material in the zone between the two cla~ping devices is stretched in the axial direction of the ~ube by shifting the clamping devices in the direction away -from one another. When PET is used, stretching by a factor of at least 3 takes place.
According to one embodiment of the invention, the
- The invention provides a blank which makes it possible that, in a container formed from the blank, both the mouth part and the neck sections and also the container body consis-t of a material which is adapted -to the occurring stresses and in which the material in the said parts is oriented to a satisfactory extent in such a way tha-t the material is stre-tched, at least in the axial direction, by a factor of more than 3.
This results in the advantage of a raised glass transition temperature Tg in all the said par1s of the container. This means that all the sai~ parts will have the same heat resistance, and this is a great advantage compared with containers which are formed according to the known technology and which, at least as far as con-tainers with mainly clear and transparent materials are concerned, have neck sections and mouth parts which-are more sensitive to heat stresses than the actual container body.
Moreover, the invention enables a container of sm~l~rmouth diameter to be manufactured, the length and diameter of the container body being matched to the storage capacity of the container in such a way that the L~)3~
-- 10 ~
smallest possible quantity of material per unit volume of storage space results.
In addition, the invention enables a cont.ainer of any desired shape of the n~ck part to be formed from the blank, the container material in the mouth part and in the neck part also being oriented and having a crystallinity of more than l~/ol this was achieved by stretching the material to the requisite extent, for example in the case of con-tai.ners of PET by stretching in the axial direction by a Eactor of more than 3. According to known technology it was hitherto not possible to obtain such a degree of orienting, unless the mouth part and neck sections of the containers wexe to consist of mainly unoriented material, in which case the neck sections merge in the shortest possible distance with oriented sections of the container body, where the wall thickness has been reduced by a factor of at least 3. This shaping represented an attem~t to reduce the size o~ that zone in the neck part, which has mainly amorphous material and low orientation and hence a low glass transition temperature Tg.
In accordance with one aspect of the invention, there is provided a tubular pre-moulding of a thermoplastic material, the pre moulding having a mouth part with adjacent neck sections at one end, a closure at the other end and a tubular section between the two ends, and the closed end and the tubular section of the pre-moulding consisting mainly of amorphous unoriented material having a crystallinity of less than 5%. The tubular pre-moulding of the invention i.s characterized in that the rnouth part with adjacent neck sections of the pre-moulding are oriented mainly in the axial direction of the pre-moulding by reducing the wall thickness by a factor corr@sponding to the reduction of th.ickness obtained in a sheet of the material monoaxially stretched into yielding, the crystal-linity of the material in the mouth part and in the adjacent neck sections being at most 5~/0~
According to a -further aspect of the invention, there is provided in a tubular pre-moulding of a thermo-plastic of polyester or polyamide type, the pre-moulding having substantially uniform initial thickness and comprising a mouth part with adjacent neck sections at one end, a closure at the other end and a tubular section between the two ends, the closed end and the tubular section of the pre-moulding consisting mainly of amorphous unoriented material having a crystallinity of less than 5%, the impro~e-ment wherein the mouth part o-f the pre-moulding, with adjacent neck sections, consists of material which is oriented substantially by a reduction in the thickness of the material while the remainder of the pre-moulding retains its original thickness and, at least in the mouth part, the material has a lower degree of orientation in the circum-ferential direction of the pre-moulding as compared to the axial direction. The crystallinity of the material in the mouth part ;;s at most 50/0, the orientation of the mouth ;' ~, , . . .
- lla -part and ad~acent neck sections of the pre-moulding by the thickness reduction providing an increased glass transition temperature Tg in the mouth part and neck sections which is suhstantially equal to the glass transition temperature of the tubular section when the amorphous material of the tubular section is oriented by a subsequent blowing of the pre~moulding to a container.
According to the invention, the tube of thermo-plastic material is clamped in between two mutually separate clamping devices. ~le material in the zone between the two cla~ping devices is stretched in the axial direction of the ~ube by shifting the clamping devices in the direction away -from one another. When PET is used, stretching by a factor of at least 3 takes place.
According to one embodiment of the invention, the
3~5i material in -the tube is stretched, while -the material is at a temperature above the glass transition tempera-ture Tg, whereas in another embodimen-t -the material is stretched in the cold state, which means that -the material is at a temperature below the glass transition temperature Tg at the beginning of the stretching step, On stretching "in the cold state", the materia], is drawn until flow sets in.
After stretching, at least the central sec-tions of the drawn material are blow-moulded at a tempera-ture above the glass transition temperature Tg against a mould, in order to form, ~or example, threads and, in some cases which may occur, parts of the adjacent neck sections, while two future mouth parts are in adjacent positions.
Subsequently, the tube is severed at the transition bet~een the two future mouth par-ts. Each of the two severed blank parts -thus produced form a tubular pre-moulding, after closing at one end and, if appropriate, reworking at the other end in order to obtain the requi'red closure surfaces.
In optional embodiments of the invention, the material is heated before the axial stretching to a tem-pera-ture above the glass transition temperature Tg 7 or the stretching step is preceded by a blow-moulding step in which the heated material is subjected to a certain expansion in order to increase -the diameter of the zone.
; In another embodiment of the invention, the mouth parts o~ the pre-mouldings are shaped by simultaneous axial stretching, and blow-moulding for the purpose of a , , /~
,~2 -radial expansion o~ the hea-ted ma-teri.al.
In cer-tain application examples, the heated ma-terial zone has a temperature profile such that one or several annular zones are at a temperature which exceeds the temperature of the adjacent material by 3-20C, pre-ferably 10-15C. The actual drawing or stretching step starts in the material zones of higher temperature.
In an application of the invention, wherein the material in the tube is,at the start of axial stre-tching of the malerial9at a tempera-ture which is less than the glass transition temperature T~, the drawing or stretching step is initiated, according to an optional embodiment of the invention, with the aid of pressure forces. This is achieved, for example, by means of a ring which sur-, rolmds -the tube, the inner surface of thering being brought into contact with the outer surface of the tube by reducing the internal diameter of the ring.
On axial stretching of the material, the external diameter of the tube is reduced. As a resul-t of the invention, it is thus possible to produce a pre-moulding 7 the mouth part of which has an external diameter which is less than the ~xternal diameter of the tube.
Equipment for carrying out the process comprises a number of stretching and blow-moulding devices, which are each provided with two clamping devices which are loca-ted at a certain spacing from one another. The clamping devices are provided for clamping a tube in, and the two sets of clamping devices are arranged in suc'h a way that they can be shifted towards one another or a~ay 3~;
, ~
-- ~3 ~
from one another. The con-tact surfaces of the cla~ping devices with the tube are cooled. Appro-priate devices are provided for heating the material in the -tube between the said sets ofclamping devices, and also the blow-moulds against which the heated.material is blown. Moreover 9 the equipment comprises elements for closing the two ends of the tube before b]ow-moulding and also elements for applying an elevated pressure to the closed cavity formed in this way. In certaln illustrative embodiments, a cylindrical rod is also fit-ted axially in the tube. Finally, an element for severing the tube into -two preferably equal parts is present~
In an embodiment of the invention, the clamping devices are arranged in such a way that the tube can rotate about its own axis. In -this way, hea-ting of the material in the zone between the two sets of clamping devices and also the se~ering of the tube into two eq~al parts are facilitated, In forming a blank, the tube is fixed between the two clamping devices, after which the la-tter are shifted in the direction away from one another, ir. certain .illus-trative embodiments after the material between -the two sets of clamping devices has first been heated to the desired temperature pro~ile and, in certain application case,s, with simultaneous radial expansion of the material in the tube or after a first radial expansion o~ the material in the tube has taken place. The length o~
displacement relative to the length of the part of the , .
- 14 ~
tube, the ma-terial of which is stretched, is selected in the case of PET ln such a way that the material reaches a crystallinity of at least 10% on axial orientationO
In some cases which may occur, the cylindrical rod is introduced into the -tube before the material is stretched.
In certain application examples, the rod is heated. To effect radial expansion, the two ends of the tube are closed, the material between the two se-ts of clamping devices is heated in some cases which may occur, and the closed space in the tube is subjec-ted to pressure, the heated material expanding in such a way -that it makes contact with the mould surfaces, for example for the pur~
pose of moulding the mouth thread and adjacent neck sections. When the material has cooled to a sufficient extent to reach dimensional stability, the tube is severed into two parts in the severing element. Each of the two parts is closed at one end by reshaping and, if appro-priate, reworked at the other end, that is to say the mouth end, in order to produce t~e requisite closing sur-faces. Thus, the pre-moulding is completed.
According to the process described above, each drawing step with subsequent severing results in ~o blank parts which, after a certain reworking and reshaping, each form a blank. In this manner, no losses of material arise in the production of pre-mouldings. Of course, the stretched material formed during the drawing step can be adaptecL in such a way that it is used for forming exclusively one single future mouth part with adjacent future neck sections. Due to the severing of parts of 33~
,~
the piece of tube 5 which can not be used for further production of -the pre-moulding, however, this leads to undesired losses of material, so that this embodiment of the invention is only used in special cases~ for example in the production of pre~mouldlngs which are intended for containers having long mouth sections and neck sections.
Figure 1 shows, in perspective view, a stretching and blow-moulding device having two sets of clamping devices, and with the two sets of clamping devices of the stretching device being in the position for receiving a piece of tube, Figure 2 shows, in perspective view, a s-tretching and blow-moulding device, with the clamping devices in the position for fixing a piece of tube, Figure 3 shows a sectional view of the stretching and . blow-moulding device during the heating of a central part of a piece of tube, Figure 4 shows a sectional view of a stretching and blow-moulding device with the piece of tube ; fixed and drawn, Figure 5 shows a sectional view of a stretching and blow moulding device with the internal volume of the piece of tube subjected to pressure in order to form the mouth sections and adjacent neck ecti ns s o Figure 6 shows a device for severing the piece of tube into two separate blank parts, Figure 7 shows, in diagrammatic view, a device for the stepwise production of blank parts for pre-~.
mouldlng s .
Figure 8 shows a sectional view of a stretching andblow-moulding device having a device for heating an annular section in the piece of tube, Figure 9 shows a sectional view of a stretching and blow-moulding device during the cold-drawing step of -the piece of tube, Figure 10 shows a sectional vie~J of a stretching and blow-moulding device af-ter the cold-drawing step of the piece of tube has been carried out, Figure 11 shows a sectional view of a stretching and blow~moulding device with the length of the : axially drawn zone increased, Figure 12 shows a partial section through a stretching and blow-mould.ing device according to Figure 11, in which the internal volume of the piece of tube has been subjected to pressure, and in particular the forming of the neck sections .- adjacen-t to the mouth part, Figure 13 shows a completed tubular pre~moulding which has been shaped from a blank part according to Figure 5, and Figure 14 shows a completed tubular pre-moulding whi.ch has been shaped from a blank part according to Figure 12.
Figures 1 and 2 show a frame on which two separate sets of clamping devices 20 a-b and 21 a-b are located.
In principle, the two sets of clamping devices consist of an upper clamping part 20a, 21a and a lower clamping par-t ~ '' " ' .
~ f -20b, 21bo In both sets o~ clamping ~evices, the upper part can be shif-ted between an open position and a closed position. In the closed position, the particular set of clamping devices fixes one end of a tube 50 in each case. The -two sets of cla~ping devices can be shifted from their starting positions (Figure 1) towards one another up to a smallest distance (Figure 2) which matches the length of -the tube 50, and from there they can be shifted back again into the particular starting position.
In the starting position, -the particular upper part assumes the open position and remains in the latter until the two sets of clamping devices have been shifted towards one another up to the said smallest distance. Xn this position, the particular upper parts assume the closed position and thus cover a relatively large part of the -tube 50, the latter being surrounded a-t the same time and being fixed by the particular set of clamping devices.
While the upper parts are still in the closed position, the two sets of clamping devices are subsequently shifted back to the starting position. The shift of the upper parts 20a, 21a of the two sets of clamping devices is effected by means of drive mechanisms 25, 26, and a drive mechanism Z4 is provided for shifting the two sets of clamping devices towards one another. The two upper par-ts slide in the grooves 22, 23 provided in the lower parts, whilst the lower parts slide in grooves 13 a-b provided in the frame 11.
A gripper 28 is provided for inserting the tube 50 into the clamping devices or removing it from the , . .
-` ,., 11~3g:~;
g clamping devices. When the two se-ts of clamping devices are at their smalles-t distance from one another, a heating ele~ent consisting of the two heating jaws 29 a-b is brought into a position in which it can heat the central sections of the tube 50. The motion of the heating jaws is effected by means of a drive mechanism 33 -with a push-and-pull bar. A lead 31 for heating the, heating jaws, for example by means of electric powera is shown in the figures.
Adjoining one of the two sets of clamping devices, a cylindrical forming and blo~ring mandrel 27 is provided.
This mandrel is moved by means of a drive mechanism 39 from and to a position in which the cylindrical part of the mandrel protrudes a little into the opening of the other set of clamping devices. The mandrel protrudes into the said opening even when the two sets of clamping devices are in their starting positions.
The external diameter of the mandrel and the internal diameter of the tube 50 are matched in such a way that the mandrel can be introduced into the tube.
Moreover, the mandrel is provided with a row o orifices 40 which lead to a cavity in the interior of the mandrel7 which cavity is connected to a line 32 for a pressure medium.
A pressure medium is fed via the lines 30a, b, c, e (the pressure line 30d is not shown in the ~igure) to the individual drive mechanisms 24, 25, 26, 33 and 39.
In Figure 3, the two sets of clamping devices 20 a-b, 21 a-b are shown in the position for the smallest ~ D ~ 3 ;~5 ~ ,~9 dis-tance between the sets. In addition, the figure shows the said cavity 42 in the mandrel 27, a gasket 41 between one end of the -tube 50 and the set of clamping devices 21 a-b and a gasket 34 between the other end of the tube 50 and the set of clamping devices 20 a-b.
A gasket 35 between the mandrel 27 and the set of clamping devices 20 a b can also be seen. An outlet valve 36 is located in the lower clarnping device 21b. In this way, the closed space which can be sub~ected to pressure through the orifices 40 is formed in the mandrel Z7.
Figure 4 shows -the two sets of clamping devices shifted back into their starting positions9 while the surrounded parts of -the tube 50 are still held firmly as before. ~he Figure shows that the mandrel 27 continues to projectinto the set ofclamping devices 21a-~ A central zone 51 of-the tube 50has beenstretched in the axial direction and has a smaller wall thickne~s than the remainder of the tube.
In Figure 5, the central zone 51 has been blow~
moulded against the mould 57 a-b. The shaping surface of the moul~ corresponds to the form of two mouth parts 52 a-b, facing one another, for containers which are tobe formed ~rom the blanksand arein the process of manufacture.
Figure 6 shows the mandrel 27 in its starting position. A severing disc 58 is located in the position ~or severing the tube 50, tha-t is to say at the transition between the two moulded mouth parts 52 a-b.
Figure 7 shows a turntable 7 which rotates about a bearing 12. Next to the turntable, a number o~
positions A-U is indicated. One frame 11 with the ..
~' , ;:
~ 3 -,2~ _ associated set of clamping devices, drive mechanisms~
tubular mandrel, heating device and the like according to Figures 1-2 is located on the turntable for each position.
In the positions, the particular working step is indicated diagrammatically by the position of mandrel, heating JawS 9 sets of clamping devices and the like.
Figure 8 shows an embodiment of the invention, which is adapted preferably for so-called cold-drawing of the tube. An annular heating element 38 is located b'etween the -two sets o~ clamping devices. By means of this heating element, the central sections o~ the tube 50 are heated to an elevated ternperature over an annular zone.
Figures9-10 rela-te to the cold-drawing of the tube 50. In Figure 9, -the formation of a centrally located drawn zone 53 has started, whilst in Figure 10 the entire centrally located dra~n zone 54 has been formed.
Figures 11 and 12 relate to a variant of the invention wherein the centrally located zone 51a of the tube 50 is longer than in the previously described embodiments of the invention. The figures show only one of the two sets of clamping devices. Figure 11 shows the position after drawing of the tube has been completed, whilst Figure 12 shows the central zone 51a (Fi~lre 11) after it has been blow-moulded against an outer mould 59. The moulding surface of the outer mould corresponds tothe shape of ~ro mutually facing mouth parts (only one, 52a, is shown in the figure) and , . .
parts of the adjacent luture neck section 60a of the containers which are to be formed from the bianks and are in the process o~ production. A zone 56, having the largest diameter in the moulded future neck sections, preferably has a diameter which is a-t least three times the original diameter o~ the tube.
Figures 13 and 14 show comp~etPd tubular pre-mouldings, the pre-moulding according to Figure 13 ha~7ing been formed from a blank part shown in Figure 5 and a pre-moulding according to Figure 14 having been formed from a blank part shown in Figure 12. At one end 5 the pre-mouldings have a mouth part 62a, b with adjacent neck sections 63a, b. At the other end the pre-mouldings have a closure 61a, b. A tubular section 64a, b can be seen between the closure 6]a, b and the neck sections 63a, b.
In the production of a pre~moulding according to the invention, a tube 50 is brought into the position shown in Figure 1 with the aid of the gripper 28. The t~ro sets of clamping devices 20 and 21 are shifted towards one another with the aid of the drive meohanism 24 un-til the two ends o~ the tube are in ~ontact with the gaskets 34 and 41. The upper clamping devices are brough-t into their closed position with the aid of the drive mechanisms 25, 26, the tube 50 being firmly held at both its ends and at the same time being enclosed over a relatively large part. This situation is shown in Figure 2. As an alternative9 the mandrel 27 was already in this phase brought beforehand into the position ~13~
_ ~2 -which is shown in Figure 3. The heating jaws 29 are brough-t into the heating position and remain in -this position for such a perio~ as is necessary for heating the materîal in the central sections of the tube to a tempera-ture below the glass transi-tion temperature Tg.
The drîve element 24 now shifts the two sets of clamping devices in the direction away from one another, the central sec-tions of the -tube being stretched, with simultaneous thinning of the tube wall, in such a way that the tube is given the appearance shown in Figure 4.
Preferably9 stretching amounts to at least a factor of 3 and the reduction in thickness -thus also amounts to a factor of 3. During the entire drawing step 9 the mandrel 27 is located in the interior of the tubeg within the stretched zone, and th~s prevents the stretched zone ~rom assuming an undesirably small diameter.
The closed space in the interior of the tube is subjected to pressure, the material being expanded into the zone concerned until it makes contact with the outer mould 57. In this step, the future mouth parts and parts of the adjacent neck sections in two blank parts connected to one another are shaped to give pre-mouldings.
On con-tact wi-th the surfaces of the outer mould, the material in the tube is cooled so that it becomes dimen-sionally stable. With simultaneous retraction of the mandrel 27 into its starting position, the outer mould is opened and a severing disc 28 divides the tube at the transition between the two future mouth parts. This produces two separate blank parts ~hich are closed at one end by reshaping and are provided with the requisi^te closing sur~aces at the other end by reworking. In this way, a tubular pre-moulding as shown in Figure 13 is sb-tained.
The design of the equipment for closing one end, and likewise for the reworking, which may be necessary, of the mouth part, is not sho~m in the figures, but this can be in accordance with any technology already known and used. Normally, closing is effected by heating the material at one end of the tube up to a temperature above the glass transition temperature Tg~ after whic'n the end is forced in the axial direction against a substan- -tially spherical shell which compresses the soft material and closes the end. Subsequently, -the gripper 28 takes the two blan~ parts formed out of the production equipment after the two sets of clamping devices have released the pre-mouldings~ Subsequently, the course of the pro-cess described above is repeated~
According to a preferred embodiment of the inven-tion, the production step described above is carried out with the aid of the equipment shown in Figure 7. In position A, th~ tube is fed to the ~lo sets of clamping devices, in position B the two sets of clamping devices are shifted in the direction towards one another, whilst simultaneously the mandrel is introduced into the tube, and in position C~E the central zone of the tube is heated 7 whilst in position F the heating process is interrupted.
In positions G-H t the central sections of the tube are stretched, in position I the outer mo~lds move into the , ,'I,S
_ 24 -moulding position, in position J -the in-terior of -the tube is subjected -to pressure and is f`ormed to give the future mouth parts with the adjacent neck sections.
In position K, the outer moulds open, whilst in position L the mandrel is retracted into its starting posi-tionO
Position M is a cooling position for stabi.l.ising the form of the tube or, alternatively, is a reserve position, whilst in position N the tube is severed into two blank parts. In posi.tion 0, the two future mouth parts are heated for reworking, if appropriate, and they obtain their final form in position P. In position R, the devices for reworking the mouth parts have assumed again their starting position, and subsequently, in position S, the blank parts have been shifted in the direction to~ards one another in order to enable the gripper to engage in position T and to enable the clamping devices to open in position U, so that the mouldings formed can be removed from the production equipment according to Fi~ure 7. Advantageously, the gripper device here transfers the blanks to devices for closing one of their ends. Such devices can either be pro-~ided independently of the equipment described in this paragraph, or they can form part of this equipment.
In the latter case, this equipment mus-t be pro-vided with a further number of posltions.
During cold-drawing of the cen-tral zone of the tube, the m~terial is heated be~ore the drawing step with the aid o~ an annular heating element 38 (Figure 8) over an annular zone within the central zone. This hea-ting ~ 3 - ~5 ~
element is preferably designed to heat the central zone as far as one of the sets o~ clamping devices. To con-trol the direction of displacement during the flow which sets in on drawing, the material is normally cooled immediately next to -the heated annulus in that direction in which it is intended tha-t the ~low step should not propagate. In the embodiments in which the en-tire material o~ the tube is to be drawn be~een the two sets of jaws, the required cooling is obtained by the cooled jaws. In other embodiments~ annular cooling devices are used which~ in principle, are arranged in a manner corresponding to the arrangement of the heating device 38 On warm-drawing of the central zone of the tube, one or several annular heating elements are used in cer~
tain application examples in order to produce the desired temperature profile in the central zone of the tube before the latter is drawn. The annular heating elements here frequently consist o~ zones o~ elevated te~perature in the heating jaws 29.
On cold-drawing o~ the material in the central zone of the tube, flow of the material sets in first in the annular zone which has been heated by the annular heating element 38. On further stretching of the cen-tral zone of the -tube, the ~low zone of the material is displaced in the direction of the other set of clamping devices, compare Figure 9, so that 9 after completion of the stretching step, a central drawn zone has formed~ the appearance o~ which is shown in Figure 10. On cold-drawing, the~ central zone has no tendency towards a ~ - "
reduction of -the internal diameter of the -tube 7 as long as stretchlng is limited to about a factor of ~. In this embodiment of the invention, it is thus not necessary to cause the mandrel 27 to assume i-ts position in the tube before the actual stretching step. Figures 11-12 show an embodiment of the invention in which the stretched central zone 51a has a greater length than in the embodi-ments o~ the invention so far described. When the in-terior of the tube is subjected to pressure, parts o~
adjacent neck sections are also formed, in addition to the two future mouth parts 9 these neck sections being given a greater diameter than that of the actual mouth part.
At this stage, it is preferable to allow the future neck section to be shaped to such an extent that the greatest rise in diameter is at least 3-fold. This has the advantage that a relatively dimensionally stable neck section is formed which, during the subsequent heating in conjunction with the shaping of the remaining part of the container, is affected only to a small extent. m e appearance of a pre-moulding, which was formed from a blank part par-tially shown in Figure 12, can be seen in Figure lL~
In the above description, it was explained how the blank parts are formed by severin~ the drawn and shaped tube. In a preferred embodiment of the invention, severing of the blank parts from one another is effected with the aid of one or several severing discs which revolve under pressure about the circumferential surface o~ the tube formed at the.transition between the two - æf~
future mouth par-ts.
It was assumed in the above descrip~tion that hea-ting o~`the central material sections of the tube is effected by heating jaws. To obtain the most uniform heating of the ma-terial possible, the tube should pre-ferably rotate relative to the heating element. To make this pos.sible, the clamplng devices are modified, if appropriate having cone-type bearings or having heating jaws which revolve about the tube.
In the case where the central sec-tions of -the tube are drawn at an initial -temperature which is below the glass transition temperature Tg, -the material is heated after the drawing step to a temperature above the glass transition temperature Tg, af-ter which -the future mouth part and parts of the adjacent neck sec-tions are shaped.
In addition to the above descrlption, the inven-tion is also comprised by the attached patent claimsO
After stretching, at least the central sec-tions of the drawn material are blow-moulded at a tempera-ture above the glass transition temperature Tg against a mould, in order to form, ~or example, threads and, in some cases which may occur, parts of the adjacent neck sections, while two future mouth parts are in adjacent positions.
Subsequently, the tube is severed at the transition bet~een the two future mouth par-ts. Each of the two severed blank parts -thus produced form a tubular pre-moulding, after closing at one end and, if appropriate, reworking at the other end in order to obtain the requi'red closure surfaces.
In optional embodiments of the invention, the material is heated before the axial stretching to a tem-pera-ture above the glass transition temperature Tg 7 or the stretching step is preceded by a blow-moulding step in which the heated material is subjected to a certain expansion in order to increase -the diameter of the zone.
; In another embodiment of the invention, the mouth parts o~ the pre-mouldings are shaped by simultaneous axial stretching, and blow-moulding for the purpose of a , , /~
,~2 -radial expansion o~ the hea-ted ma-teri.al.
In cer-tain application examples, the heated ma-terial zone has a temperature profile such that one or several annular zones are at a temperature which exceeds the temperature of the adjacent material by 3-20C, pre-ferably 10-15C. The actual drawing or stretching step starts in the material zones of higher temperature.
In an application of the invention, wherein the material in the tube is,at the start of axial stre-tching of the malerial9at a tempera-ture which is less than the glass transition temperature T~, the drawing or stretching step is initiated, according to an optional embodiment of the invention, with the aid of pressure forces. This is achieved, for example, by means of a ring which sur-, rolmds -the tube, the inner surface of thering being brought into contact with the outer surface of the tube by reducing the internal diameter of the ring.
On axial stretching of the material, the external diameter of the tube is reduced. As a resul-t of the invention, it is thus possible to produce a pre-moulding 7 the mouth part of which has an external diameter which is less than the ~xternal diameter of the tube.
Equipment for carrying out the process comprises a number of stretching and blow-moulding devices, which are each provided with two clamping devices which are loca-ted at a certain spacing from one another. The clamping devices are provided for clamping a tube in, and the two sets of clamping devices are arranged in suc'h a way that they can be shifted towards one another or a~ay 3~;
, ~
-- ~3 ~
from one another. The con-tact surfaces of the cla~ping devices with the tube are cooled. Appro-priate devices are provided for heating the material in the -tube between the said sets ofclamping devices, and also the blow-moulds against which the heated.material is blown. Moreover 9 the equipment comprises elements for closing the two ends of the tube before b]ow-moulding and also elements for applying an elevated pressure to the closed cavity formed in this way. In certaln illustrative embodiments, a cylindrical rod is also fit-ted axially in the tube. Finally, an element for severing the tube into -two preferably equal parts is present~
In an embodiment of the invention, the clamping devices are arranged in such a way that the tube can rotate about its own axis. In -this way, hea-ting of the material in the zone between the two sets of clamping devices and also the se~ering of the tube into two eq~al parts are facilitated, In forming a blank, the tube is fixed between the two clamping devices, after which the la-tter are shifted in the direction away from one another, ir. certain .illus-trative embodiments after the material between -the two sets of clamping devices has first been heated to the desired temperature pro~ile and, in certain application case,s, with simultaneous radial expansion of the material in the tube or after a first radial expansion o~ the material in the tube has taken place. The length o~
displacement relative to the length of the part of the , .
- 14 ~
tube, the ma-terial of which is stretched, is selected in the case of PET ln such a way that the material reaches a crystallinity of at least 10% on axial orientationO
In some cases which may occur, the cylindrical rod is introduced into the -tube before the material is stretched.
In certain application examples, the rod is heated. To effect radial expansion, the two ends of the tube are closed, the material between the two se-ts of clamping devices is heated in some cases which may occur, and the closed space in the tube is subjec-ted to pressure, the heated material expanding in such a way -that it makes contact with the mould surfaces, for example for the pur~
pose of moulding the mouth thread and adjacent neck sections. When the material has cooled to a sufficient extent to reach dimensional stability, the tube is severed into two parts in the severing element. Each of the two parts is closed at one end by reshaping and, if appro-priate, reworked at the other end, that is to say the mouth end, in order to produce t~e requisite closing sur-faces. Thus, the pre-moulding is completed.
According to the process described above, each drawing step with subsequent severing results in ~o blank parts which, after a certain reworking and reshaping, each form a blank. In this manner, no losses of material arise in the production of pre-mouldings. Of course, the stretched material formed during the drawing step can be adaptecL in such a way that it is used for forming exclusively one single future mouth part with adjacent future neck sections. Due to the severing of parts of 33~
,~
the piece of tube 5 which can not be used for further production of -the pre-moulding, however, this leads to undesired losses of material, so that this embodiment of the invention is only used in special cases~ for example in the production of pre~mouldlngs which are intended for containers having long mouth sections and neck sections.
Figure 1 shows, in perspective view, a stretching and blow-moulding device having two sets of clamping devices, and with the two sets of clamping devices of the stretching device being in the position for receiving a piece of tube, Figure 2 shows, in perspective view, a s-tretching and blow-moulding device, with the clamping devices in the position for fixing a piece of tube, Figure 3 shows a sectional view of the stretching and . blow-moulding device during the heating of a central part of a piece of tube, Figure 4 shows a sectional view of a stretching and blow-moulding device with the piece of tube ; fixed and drawn, Figure 5 shows a sectional view of a stretching and blow moulding device with the internal volume of the piece of tube subjected to pressure in order to form the mouth sections and adjacent neck ecti ns s o Figure 6 shows a device for severing the piece of tube into two separate blank parts, Figure 7 shows, in diagrammatic view, a device for the stepwise production of blank parts for pre-~.
mouldlng s .
Figure 8 shows a sectional view of a stretching andblow-moulding device having a device for heating an annular section in the piece of tube, Figure 9 shows a sectional view of a stretching and blow-moulding device during the cold-drawing step of -the piece of tube, Figure 10 shows a sectional vie~J of a stretching and blow-moulding device af-ter the cold-drawing step of the piece of tube has been carried out, Figure 11 shows a sectional view of a stretching and blow~moulding device with the length of the : axially drawn zone increased, Figure 12 shows a partial section through a stretching and blow-mould.ing device according to Figure 11, in which the internal volume of the piece of tube has been subjected to pressure, and in particular the forming of the neck sections .- adjacen-t to the mouth part, Figure 13 shows a completed tubular pre~moulding which has been shaped from a blank part according to Figure 5, and Figure 14 shows a completed tubular pre-moulding whi.ch has been shaped from a blank part according to Figure 12.
Figures 1 and 2 show a frame on which two separate sets of clamping devices 20 a-b and 21 a-b are located.
In principle, the two sets of clamping devices consist of an upper clamping part 20a, 21a and a lower clamping par-t ~ '' " ' .
~ f -20b, 21bo In both sets o~ clamping ~evices, the upper part can be shif-ted between an open position and a closed position. In the closed position, the particular set of clamping devices fixes one end of a tube 50 in each case. The -two sets of cla~ping devices can be shifted from their starting positions (Figure 1) towards one another up to a smallest distance (Figure 2) which matches the length of -the tube 50, and from there they can be shifted back again into the particular starting position.
In the starting position, -the particular upper part assumes the open position and remains in the latter until the two sets of clamping devices have been shifted towards one another up to the said smallest distance. Xn this position, the particular upper parts assume the closed position and thus cover a relatively large part of the -tube 50, the latter being surrounded a-t the same time and being fixed by the particular set of clamping devices.
While the upper parts are still in the closed position, the two sets of clamping devices are subsequently shifted back to the starting position. The shift of the upper parts 20a, 21a of the two sets of clamping devices is effected by means of drive mechanisms 25, 26, and a drive mechanism Z4 is provided for shifting the two sets of clamping devices towards one another. The two upper par-ts slide in the grooves 22, 23 provided in the lower parts, whilst the lower parts slide in grooves 13 a-b provided in the frame 11.
A gripper 28 is provided for inserting the tube 50 into the clamping devices or removing it from the , . .
-` ,., 11~3g:~;
g clamping devices. When the two se-ts of clamping devices are at their smalles-t distance from one another, a heating ele~ent consisting of the two heating jaws 29 a-b is brought into a position in which it can heat the central sections of the tube 50. The motion of the heating jaws is effected by means of a drive mechanism 33 -with a push-and-pull bar. A lead 31 for heating the, heating jaws, for example by means of electric powera is shown in the figures.
Adjoining one of the two sets of clamping devices, a cylindrical forming and blo~ring mandrel 27 is provided.
This mandrel is moved by means of a drive mechanism 39 from and to a position in which the cylindrical part of the mandrel protrudes a little into the opening of the other set of clamping devices. The mandrel protrudes into the said opening even when the two sets of clamping devices are in their starting positions.
The external diameter of the mandrel and the internal diameter of the tube 50 are matched in such a way that the mandrel can be introduced into the tube.
Moreover, the mandrel is provided with a row o orifices 40 which lead to a cavity in the interior of the mandrel7 which cavity is connected to a line 32 for a pressure medium.
A pressure medium is fed via the lines 30a, b, c, e (the pressure line 30d is not shown in the ~igure) to the individual drive mechanisms 24, 25, 26, 33 and 39.
In Figure 3, the two sets of clamping devices 20 a-b, 21 a-b are shown in the position for the smallest ~ D ~ 3 ;~5 ~ ,~9 dis-tance between the sets. In addition, the figure shows the said cavity 42 in the mandrel 27, a gasket 41 between one end of the -tube 50 and the set of clamping devices 21 a-b and a gasket 34 between the other end of the tube 50 and the set of clamping devices 20 a-b.
A gasket 35 between the mandrel 27 and the set of clamping devices 20 a b can also be seen. An outlet valve 36 is located in the lower clarnping device 21b. In this way, the closed space which can be sub~ected to pressure through the orifices 40 is formed in the mandrel Z7.
Figure 4 shows -the two sets of clamping devices shifted back into their starting positions9 while the surrounded parts of -the tube 50 are still held firmly as before. ~he Figure shows that the mandrel 27 continues to projectinto the set ofclamping devices 21a-~ A central zone 51 of-the tube 50has beenstretched in the axial direction and has a smaller wall thickne~s than the remainder of the tube.
In Figure 5, the central zone 51 has been blow~
moulded against the mould 57 a-b. The shaping surface of the moul~ corresponds to the form of two mouth parts 52 a-b, facing one another, for containers which are tobe formed ~rom the blanksand arein the process of manufacture.
Figure 6 shows the mandrel 27 in its starting position. A severing disc 58 is located in the position ~or severing the tube 50, tha-t is to say at the transition between the two moulded mouth parts 52 a-b.
Figure 7 shows a turntable 7 which rotates about a bearing 12. Next to the turntable, a number o~
positions A-U is indicated. One frame 11 with the ..
~' , ;:
~ 3 -,2~ _ associated set of clamping devices, drive mechanisms~
tubular mandrel, heating device and the like according to Figures 1-2 is located on the turntable for each position.
In the positions, the particular working step is indicated diagrammatically by the position of mandrel, heating JawS 9 sets of clamping devices and the like.
Figure 8 shows an embodiment of the invention, which is adapted preferably for so-called cold-drawing of the tube. An annular heating element 38 is located b'etween the -two sets o~ clamping devices. By means of this heating element, the central sections o~ the tube 50 are heated to an elevated ternperature over an annular zone.
Figures9-10 rela-te to the cold-drawing of the tube 50. In Figure 9, -the formation of a centrally located drawn zone 53 has started, whilst in Figure 10 the entire centrally located dra~n zone 54 has been formed.
Figures 11 and 12 relate to a variant of the invention wherein the centrally located zone 51a of the tube 50 is longer than in the previously described embodiments of the invention. The figures show only one of the two sets of clamping devices. Figure 11 shows the position after drawing of the tube has been completed, whilst Figure 12 shows the central zone 51a (Fi~lre 11) after it has been blow-moulded against an outer mould 59. The moulding surface of the outer mould corresponds tothe shape of ~ro mutually facing mouth parts (only one, 52a, is shown in the figure) and , . .
parts of the adjacent luture neck section 60a of the containers which are to be formed from the bianks and are in the process o~ production. A zone 56, having the largest diameter in the moulded future neck sections, preferably has a diameter which is a-t least three times the original diameter o~ the tube.
Figures 13 and 14 show comp~etPd tubular pre-mouldings, the pre-moulding according to Figure 13 ha~7ing been formed from a blank part shown in Figure 5 and a pre-moulding according to Figure 14 having been formed from a blank part shown in Figure 12. At one end 5 the pre-mouldings have a mouth part 62a, b with adjacent neck sections 63a, b. At the other end the pre-mouldings have a closure 61a, b. A tubular section 64a, b can be seen between the closure 6]a, b and the neck sections 63a, b.
In the production of a pre~moulding according to the invention, a tube 50 is brought into the position shown in Figure 1 with the aid of the gripper 28. The t~ro sets of clamping devices 20 and 21 are shifted towards one another with the aid of the drive meohanism 24 un-til the two ends o~ the tube are in ~ontact with the gaskets 34 and 41. The upper clamping devices are brough-t into their closed position with the aid of the drive mechanisms 25, 26, the tube 50 being firmly held at both its ends and at the same time being enclosed over a relatively large part. This situation is shown in Figure 2. As an alternative9 the mandrel 27 was already in this phase brought beforehand into the position ~13~
_ ~2 -which is shown in Figure 3. The heating jaws 29 are brough-t into the heating position and remain in -this position for such a perio~ as is necessary for heating the materîal in the central sections of the tube to a tempera-ture below the glass transi-tion temperature Tg.
The drîve element 24 now shifts the two sets of clamping devices in the direction away from one another, the central sec-tions of the -tube being stretched, with simultaneous thinning of the tube wall, in such a way that the tube is given the appearance shown in Figure 4.
Preferably9 stretching amounts to at least a factor of 3 and the reduction in thickness -thus also amounts to a factor of 3. During the entire drawing step 9 the mandrel 27 is located in the interior of the tubeg within the stretched zone, and th~s prevents the stretched zone ~rom assuming an undesirably small diameter.
The closed space in the interior of the tube is subjected to pressure, the material being expanded into the zone concerned until it makes contact with the outer mould 57. In this step, the future mouth parts and parts of the adjacent neck sections in two blank parts connected to one another are shaped to give pre-mouldings.
On con-tact wi-th the surfaces of the outer mould, the material in the tube is cooled so that it becomes dimen-sionally stable. With simultaneous retraction of the mandrel 27 into its starting position, the outer mould is opened and a severing disc 28 divides the tube at the transition between the two future mouth parts. This produces two separate blank parts ~hich are closed at one end by reshaping and are provided with the requisi^te closing sur~aces at the other end by reworking. In this way, a tubular pre-moulding as shown in Figure 13 is sb-tained.
The design of the equipment for closing one end, and likewise for the reworking, which may be necessary, of the mouth part, is not sho~m in the figures, but this can be in accordance with any technology already known and used. Normally, closing is effected by heating the material at one end of the tube up to a temperature above the glass transition temperature Tg~ after whic'n the end is forced in the axial direction against a substan- -tially spherical shell which compresses the soft material and closes the end. Subsequently, -the gripper 28 takes the two blan~ parts formed out of the production equipment after the two sets of clamping devices have released the pre-mouldings~ Subsequently, the course of the pro-cess described above is repeated~
According to a preferred embodiment of the inven-tion, the production step described above is carried out with the aid of the equipment shown in Figure 7. In position A, th~ tube is fed to the ~lo sets of clamping devices, in position B the two sets of clamping devices are shifted in the direction towards one another, whilst simultaneously the mandrel is introduced into the tube, and in position C~E the central zone of the tube is heated 7 whilst in position F the heating process is interrupted.
In positions G-H t the central sections of the tube are stretched, in position I the outer mo~lds move into the , ,'I,S
_ 24 -moulding position, in position J -the in-terior of -the tube is subjected -to pressure and is f`ormed to give the future mouth parts with the adjacent neck sections.
In position K, the outer moulds open, whilst in position L the mandrel is retracted into its starting posi-tionO
Position M is a cooling position for stabi.l.ising the form of the tube or, alternatively, is a reserve position, whilst in position N the tube is severed into two blank parts. In posi.tion 0, the two future mouth parts are heated for reworking, if appropriate, and they obtain their final form in position P. In position R, the devices for reworking the mouth parts have assumed again their starting position, and subsequently, in position S, the blank parts have been shifted in the direction to~ards one another in order to enable the gripper to engage in position T and to enable the clamping devices to open in position U, so that the mouldings formed can be removed from the production equipment according to Fi~ure 7. Advantageously, the gripper device here transfers the blanks to devices for closing one of their ends. Such devices can either be pro-~ided independently of the equipment described in this paragraph, or they can form part of this equipment.
In the latter case, this equipment mus-t be pro-vided with a further number of posltions.
During cold-drawing of the cen-tral zone of the tube, the m~terial is heated be~ore the drawing step with the aid o~ an annular heating element 38 (Figure 8) over an annular zone within the central zone. This hea-ting ~ 3 - ~5 ~
element is preferably designed to heat the central zone as far as one of the sets o~ clamping devices. To con-trol the direction of displacement during the flow which sets in on drawing, the material is normally cooled immediately next to -the heated annulus in that direction in which it is intended tha-t the ~low step should not propagate. In the embodiments in which the en-tire material o~ the tube is to be drawn be~een the two sets of jaws, the required cooling is obtained by the cooled jaws. In other embodiments~ annular cooling devices are used which~ in principle, are arranged in a manner corresponding to the arrangement of the heating device 38 On warm-drawing of the central zone of the tube, one or several annular heating elements are used in cer~
tain application examples in order to produce the desired temperature profile in the central zone of the tube before the latter is drawn. The annular heating elements here frequently consist o~ zones o~ elevated te~perature in the heating jaws 29.
On cold-drawing o~ the material in the central zone of the tube, flow of the material sets in first in the annular zone which has been heated by the annular heating element 38. On further stretching of the cen-tral zone of the -tube, the ~low zone of the material is displaced in the direction of the other set of clamping devices, compare Figure 9, so that 9 after completion of the stretching step, a central drawn zone has formed~ the appearance o~ which is shown in Figure 10. On cold-drawing, the~ central zone has no tendency towards a ~ - "
reduction of -the internal diameter of the -tube 7 as long as stretchlng is limited to about a factor of ~. In this embodiment of the invention, it is thus not necessary to cause the mandrel 27 to assume i-ts position in the tube before the actual stretching step. Figures 11-12 show an embodiment of the invention in which the stretched central zone 51a has a greater length than in the embodi-ments o~ the invention so far described. When the in-terior of the tube is subjected to pressure, parts o~
adjacent neck sections are also formed, in addition to the two future mouth parts 9 these neck sections being given a greater diameter than that of the actual mouth part.
At this stage, it is preferable to allow the future neck section to be shaped to such an extent that the greatest rise in diameter is at least 3-fold. This has the advantage that a relatively dimensionally stable neck section is formed which, during the subsequent heating in conjunction with the shaping of the remaining part of the container, is affected only to a small extent. m e appearance of a pre-moulding, which was formed from a blank part par-tially shown in Figure 12, can be seen in Figure lL~
In the above description, it was explained how the blank parts are formed by severin~ the drawn and shaped tube. In a preferred embodiment of the invention, severing of the blank parts from one another is effected with the aid of one or several severing discs which revolve under pressure about the circumferential surface o~ the tube formed at the.transition between the two - æf~
future mouth par-ts.
It was assumed in the above descrip~tion that hea-ting o~`the central material sections of the tube is effected by heating jaws. To obtain the most uniform heating of the ma-terial possible, the tube should pre-ferably rotate relative to the heating element. To make this pos.sible, the clamplng devices are modified, if appropriate having cone-type bearings or having heating jaws which revolve about the tube.
In the case where the central sec-tions of -the tube are drawn at an initial -temperature which is below the glass transition temperature Tg, -the material is heated after the drawing step to a temperature above the glass transition temperature Tg, af-ter which -the future mouth part and parts of the adjacent neck sec-tions are shaped.
In addition to the above descrlption, the inven-tion is also comprised by the attached patent claimsO
Claims (24)
1. A tubular pre-moulding of a thermoplastic material, the pre-moulding having a mouth part with adjacent neck sections at one end, a closure at the other end and a tubular section between the two ends, and the closed end and the tubular section of the pre-moulding consisting mainly of amorphous unoriented material having a crystallinity of less than 5%, characterized in that the mouth part with adjacent neck sections of the pre-moulding are oriented mainly in the axial direction of the pre-moulding by reducing the wall thickness by a factor corresponding to the reduction of thickness obtained in a sheet of the material monoaxially stretched into yielding, the crystallinity of the material in the mouth part and in the adjacent neck sections being at most 50%.
2. A tubular pre-moulding according to claim 1, wherein the thermoplastic material is of polyester or polyamide type.
3. A tubular pre-moulding according to claim 2, of polyethylene terephthalate.
4. A tubular pre-moulding according to claim 1, wherein said closure is spherical.
5. A tubular pre-moulding according to claim 1, wherein at least the mouth part has a degree of orien-tation in the circumferential direction of the pre-moulding.
6. A tubular pre-moulding according to claim 2, wherein the wall thickness is reduced by a factor of at least about 3.
7. A tubular pre-moulding according to claim 4 wherein the mouth part has a lower degree of orienta-tion in the circumferential direction of the pre-moulding.
8. A tubular pre-moulding according to claim 1, wherein the crystallinity of the material in the mouth part and in the adjacent neck sections is between 10 and 20%.
9. A tubular pre-moulding according to claim 1, characterized in that the material in the neck sections adjoining the mouth part is oriented in the axial direc-tion of the pre-moulding by thinning the original thick-ness of the material and is oriented in the circumfer-ential direction of the pre-moulding by stretching by means of a blow-moulding process while the material is at a temperature above the glass transition temperature (Tg), the crystallinity being at most 50%.
10. A tubular pre-moulding according to claim 3, characterized in that the material in the neck sections adjoining the mouth part is oriented in the axial di-rection of the pre-moulding by thinning the original thickness of the material by a factor of at least about 3 and is oriented in the circumferential direc-tion of the pre-moulding by stretching by means of a blow-moulding process while the material is at a tem-perature above the glass transition temperature (Tg), the crystallinity being at most 50%.
11. A tubular pre-moulding according to claim 9 and 10, wherein the crystallinity in the mouth part and the neck section is between 10 and 35%.
12. A tubular pre-moulding according to claim 1 characterized in that in the mouth part, the material having a crystallinity resulting from the orientation, is at most about 20%.
13. A tubular pre-moulding according to claim 12, characterized in that in the mouth part, the material having a crystallinity resulting from the orientation, is between about 10 and 17%.
14. A tubular pre-moulding according to one of claims 1 to 3, characterized in that in the neck sec-tions adjacent to the mouth part, the material having a crystallinity resulting from the orientation, is at most about 34%.
. ,
. ,
15. A tubular pre-moulding according to one of claims 1 to 3, characterized in that in the neck sec-tions adjacent to the mouth part the material having a crystallinity deriving from the orientation is bet-ween about 12 and 30%.
16. A tubular pre-moulding of a thermoplastic of polyester or polyamide type, the pre-moulding having substantially uniform initial thickness and comprising a mouth part with adjacent neck sections at one end, a closure at the other end and a tubular section between the two ends, the closed end and the tubular section of the pre-moulding consisting mainly of amorphous unoriented material having a crystallinity of less than 5%, the improvement wherein the mouth part of the pre-moulding, with adjacent neck sections, consists of material which is oriented substantially by a reduction in the thickness of the material while the remainder of the pre-moulding retains its original thickness and, at least in the mouth part, said material has a lower degree of orientation in the cir-cumferential direction of the pre-moulding as compared to the axial direction, the crystallinity of the material in the mouth part being at most 50%, the orientation of the mouth part and adjacent neck sec-tions of the pre-moulding by the thickness reduction providing an increased glass transition temperature Tg in said mouth part and neck sections which is sub-stantially equal to the glass transition temperature of said tubular section when the amorphous material of the tubular section is oriented by a subsequent blowing of the pre-moulding to a container.
17. A tubular pre-moulding according to claim 16, wherein the material in the neck sections adjoining the mouth part is oriented in the axial direction of the pre-moulding by thinning the original thickness of the material by a factor of at least about 3 and is oriented in the circumferential direction of the pre-moulding by stretching by means of a blow-moulding process while the material is at a temperature above the glass tran-sition temperature (Tg), the crystallinity assuming a value of at most 50%.
18. A tubular pre-moulding according to claim 16 or 17, wherein in the mouth part the material having a crystallinity resulting from the orientation is at most about 20%.
19. A tubular pre-moulding according to claim 16 or 17, wherein in the neck sections adjacent to the mouth part the material having a crystallinity re-sulting from the orientation is at most about 34%.
20. A tubular pre-moulding according to claim 16 wherein the thermoplastic of the pre-moulding is poly-ethylene terephthalate.
21. A tubular pre-moulding according to claim 17, wherein the thermoplastic of the pre-moulding is poly-ethylene terephthalate.
22. A tubular pre-moulding according to claim 20 or 21, wherein the crystallinity of the material in the mouth part is between 10 and 20%.
23. A tubular pre-moulding according to claim 16, wherein the reduced thickness of said mouth part and adjacent neck sections is related to the thickness of the amorphous unoriented material of said tubular section and closed end such that upon blow moulding the resulting product has a substantially uniform wall thickness therethroughout.
24. A tubular pre-moulding of polyethylene tere-phthalate comprising a mouth part with adjacent neck sections at one end, a closure at the other end, and a tubular section between the two ends, said closure and tubular section consisting essentially of amorphous, unoriented material having a crystallinity of less than 5%, the material of said mouth part and adjacent neck sections being oriented substantially monoaxially by a reduction of thickness of the material by a factor of at least about 3 while the remainder of the pre-moulding retains its original thickness and its amor-phous unoriented state whereby upon moulding of said pre-moulding the resulting article is provided with said mouth part and neck sections and a body of bi-axially oriented material which have substantially equalized values of glass transition temperature (Tg).
Priority Applications (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000352909A CA1190365A (en) | 1980-05-28 | 1980-05-28 | Process for the production of a blank for containers and blank produced by the process |
| CA000466796A CA1205264A (en) | 1979-06-11 | 1984-10-31 | Process for the production of a blank for containers and blank produced by the process |
| CA000487316A CA1210915A (en) | 1979-06-11 | 1985-07-23 | Process for the production of a blank for containers and blank produced by the process |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000352909A CA1190365A (en) | 1980-05-28 | 1980-05-28 | Process for the production of a blank for containers and blank produced by the process |
Related Child Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000466796A Division CA1205264A (en) | 1979-06-11 | 1984-10-31 | Process for the production of a blank for containers and blank produced by the process |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1190365A true CA1190365A (en) | 1985-07-16 |
Family
ID=4117052
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000352909A Expired CA1190365A (en) | 1979-06-11 | 1980-05-28 | Process for the production of a blank for containers and blank produced by the process |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1190365A (en) |
-
1980
- 1980-05-28 CA CA000352909A patent/CA1190365A/en not_active Expired
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| US4380525A (en) | Process for the production of a blank for subsequent shaping by blow-molding | |
| US4374878A (en) | Blank adapted to be blown into a container and providing orientation of the material in the mouth and neck as well as the body | |
| US6062408A (en) | Wide mouth hot fill container | |
| US6237791B1 (en) | Wide mouth hot fill container | |
| EP0200564A2 (en) | Method for producing a hot fillable, collapse resistant polyester container without the need to utilize set process techniques and/or non-conventional container geometries | |
| JPS625781B2 (en) | ||
| US4758452A (en) | Articles formed by drawing and blow-moulding | |
| MX2010008485A (en) | Preform and container having debossed support flange. | |
| EP0204810A1 (en) | Container, method and apparatus for manufacturing the same. | |
| JP2009524561A (en) | Blow molded container with thread groove | |
| JPS6243850B2 (en) | ||
| KR20010023826A (en) | Container with integral handle, preform and method of manufacture | |
| NZ202523A (en) | A method of producing a container from a tubular blank of thermoplastic material | |
| JP2001526598A (en) | Improved multilayer container and preform | |
| CA1190365A (en) | Process for the production of a blank for containers and blank produced by the process | |
| CA1158826A (en) | Manufacture of articles by drawing | |
| US4511322A (en) | Apparatus for the manufacture of a cup-like article from polyethylene terephthalate or similar material | |
| CA1205264A (en) | Process for the production of a blank for containers and blank produced by the process | |
| CA1210915A (en) | Process for the production of a blank for containers and blank produced by the process | |
| IE49904B1 (en) | A process and apparatus for manufacturing tubular pre-mouldings of thermoplastic material | |
| JPS6387219A (en) | Manufacture of biaxially oriented polyester vessel | |
| JPS58185227A (en) | Manufacture of stretched polyester bottle | |
| JPS58153618A (en) | Manufacture of polyester stretched blow molding bottle | |
| MXPA99009207A (en) | Wide mouth hot fill container |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |