GB2420338A

GB2420338A - Improvements in and relating to packaging

Info

Publication number: GB2420338A
Application number: GB0425592A
Authority: GB
Inventors: Nicholas Martin Cohen
Original assignee: Individual
Current assignee: Individual
Priority date: 2004-11-20
Filing date: 2004-11-20
Publication date: 2006-05-24
Anticipated expiration: 2024-11-20
Also published as: GB2420338B; GB0822695D0; GB2454995A; GB0425592D0; GB2454995B

Abstract

The invention provides an apparatus 101 for forming a weak portion (19 figure 1) in a plastics sheet (7 figure 1), said apparatus 101 comprising a thinning member 103 for engaging a surface of the plastics sheet and means to move said plastics sheet relative to a surface of the thinning member 103 such that a part of the surface of the sheet can be engaged and removed by the thinning member 103 to reduce the sheet thickness and provide a weak portion in the sheet which is thinner than parts of the sheet adjacent thereto. Also provided are an article of packaging (1 figure 1) comprising a plastics sheet having a weak portion and a method of manufacturing a product comprising a plastics sheet having a weak portion. The article may be a sealable bag for a medical sample container or anti-static packaging for electronics components.

Description

IMPROVEMENTS IN AND RELATING TO PACKAGING

Field of the Invention

The present invention relates to packaging, to methods for the production of packaging and to apparatus for use in the production of packaging.

Background to the Invent ion

Medical samples are often taken at a first location and then packaged and transported to a second location for testing.

Before a medical sample (such as blood or urine), held within a primary container (such as a specimen pot) is transported, it is desirable that the primary container be enclosed within a secondary container (such as a bag) in order that the sample can be contained should it leak from the primary container.

In order to be effective at containing a sample once it has leaked from a primary container the secondary container must be sealed such that it is substantially liquid tight.

After transportation the secondary container must be breached to access the primary container and thus the sample.

In order to avoid excessively bulky packaging the secondary container generally comprises a plastics bag.

GB2221208 discloses a form assembly comprising such a bag.

In use, the secondary container may be breached by creating an opening into the bag. However, this may be a laborious task. Plastics bags can be difficult to tear open as plastics material can have a tendency to stretch rather than tear. Furthermore, the use of sharp objects to cut into such bags is undesirable because of the health and safety implications of a person cutting themselves while opening the bag.

A known method of making material easier to tear is to provide it with perforations. However, this is unsuitable for use with bags for containing medical samples as the sample could egress through the perforated parts.

Sealable bags are also employed in a number of other applications. For example, they can be used to provide anti-static packaging to protect electronics components.

Again however, once sealed such bags can be difficult to open.

There is thus a need for an alternative form of packaging.

Accordingly, the present invention aims to address at least one disadvantage associated with the prior art whether discussed herein or otherwise.

Summary of the Invention

According to a first aspect of the present invention there is provided an article of packaging having a closeable opening and which comprises a plastics sheet having a weak portion to aid tearing of the sheet such that, in use, once closed the packaging may be breached by a user creating an aperture at the weak portion and wherein the n 3 weak portion of the sheet is thinner than parts of the sheet adjacent thereto.

Suitably, the weak portion is substantially liquid tight.

Suitably, the article of packaging is sealable to provide a substantially liquid tight package. The article of packaging may thus be arranged such that the opening can be sealed closed.

Suitably, the article of packaging is arranged to receive a medical sample contained within a primary container.

The article of packaging may thus provide a secondary container to contain the sample should the primary container leak.

Suitably, the plastics sheet may preferentially tear at the weak portion. In use, a user may thus breach the plastics sheet by pulling the plastic sheet from opposed sides of the weak portion to cause the sheet to break at the weak portion.

The weak portion suitably does not comprise any apertures.

The plastics sheet may thus not be perforated.

Suitably, the weak portion comprises a line of weakness.

Suitably, said line of weakness has a length of at least 2cm, preferably at least 5cm, for example of at least 10cm. Suitably, said line of weakness has a width of at least 1mm, preferably of between 2 and 10mm, more preferably of between 2 and 5mm, for example of around 3mm.

Suitably, the plastics sheet has substantially the same thickness throughout its extent with the exception of the weak portion.

Suitably, the plastics sheet is manufactured with substantially the same thickness throughout its extent and the weak portion is formed by subsequently reducing the thickness of a part of the plastics sheet.

Suitably the plastics sheet has a thickness of between 25 microns and 100 microns at the weak portion.

Suitably, the plastics sheet comprises polyethene.

Suitably, the article of packaging comprises a plastics bag. Suitably, the plastics bag comprises first and second opposed sides and the weak portion is provided on only one side.

Suitably, the bag comprises an opening through which an object can be loaded into the bag and sealing means for substantially sealing the bag once the object is loaded into the bag.

Suitably, the sealing means comprises an adhesive strip.

Suitably, the sealing means comprises a flap attached to a first side of the bag and arranged to fold over the opening to be adhered to a second side of the bag.

Suitably, the packaging comprises a paper sheet attached to the bag. Suitably, the paper sheet is attached to a flap of the bag.

In use, information relating to an object loaded into the article of packaging may be recorded on the paper sheet.

Suitably, the paper sheet is printed with information fields to be filled in by a user. In use, the object loaded into the article of packaging comprises a medical sample in a specimen pot and the information recorded on the paper sheet may relate thereto.

According to a second aspect of the present invention there is provided a method of manufacturing a product comprising a plastics sheet having a weak portion, which weak portion can aid tearing of the sheet in use and is thinner than parts of the sheet adjacent thereto and wherein the sheet is manufactured with substantially the same thickness throughout its extent and the weak portion is formed by subsequently reducing the thickness of a part of the sheet.

Suitably, the plastics sheet comprises a plastics sheet web.

Suitably, the method comprises a method of forming bags.

Preferably, the method comprises a method of forming articles of packaging according to the first aspect.

The method may comprise a method of forming products comprising bags which comprise first and second plastics sheets and have a paper sheet attached thereto.

Suitably, the method comprises conjoining first and second plastics sheet webs. Suitably, the method comprises conjoining a first plastics sheet web and a paper sheet web.

Suitably, the method comprises forming cuts in the conjoined webs to create a plurality of products each comprising a bag.

Suitably, the method comprises forming a weak portion in a plastics sheet web, preferably in the second plastics sheet web. The weak portion may thus be formed before individual bags are cut from the conjoined webs.

The weak portion may be formed and the webs then sealed together to form bags and the web may then be cut to separate the bags.

Alternatively, the webs may be sealed together to form bags and the weak portion may then be formed and the web may then be cut to separate the bags.

Suitably, the method comprises creating a weak portion having no apertures. Thus, the method suitably does not comprise perforating the plastics sheet. Suitably, the method produces a weak portion which is substantially liquid tight.

Suitably, the method comprises forming a line of weakness in a plastics sheet.

Suitably the method comprises causing a plastics sheet to move relative to a surface of a thinning member such that a part of the surface of the sheet is engaged and removed by the thinning member to reduce the sheet thickness and provide a weak portion. fl 7

Suitably, the method comprises causing a plastics sheet to travel past a thinning member.

Suitably, the plastics sheet is caused to travel at a speed of 0.1 to 2 m s 1, preferably at around 1 m s.

Suitably, the thinning member comprises a grinding member which may grind material from the sheet surface.

Suitably, the thinning member is moveable, preferably rotatable. Suitably, the thinning member comprises a wheel. Preferably, the thinning member comprises a grinding wheel.

Suitably, the method comprises moving, preferably rotating a thinning member such that the surface thereof which engages the plastics sheet moves.

Suitably, the method comprises causing the surface of the thinning member which engages the plastics sheet to travel in a counter direction to that in which the plastics sheet is caused to travel.

The greater the differential between the speeds of the plastics sheet and the surface of the thinning member the cleaner may be the tear, in use, when the bag is torn open at the weak portion.

Suitably, the method comprises rotating a thinning member having a diameter of between 10 and 40mm at a speed of between 10,000 and 20,000 RPM.

The method may employ an apparatus according to the third aspect.

According to a third aspect of the present invention there is provided an apparatus for forming a weak portion in a plastics sheet, said apparatus comprising a thinning member for engaging a surface of the plastics sheet and means to move a plastics sheet relative to a surface of the thinning member such that a part of the surface of the sheet can be engaged and removed by the thinning member to reduce the sheet thickness and provide a weak portion in the sheet which is thinner than parts of the sheet adjacent thereto.

Suitably, the plastics sheet comprises a plastics sheet web. The apparatus may be arranged to form a weak portion in a second plastics sheet web which is conjoined to a first plastics sheet web. The first plastics sheet web may be conjoined to a paper sheet web.

Suitably, the apparatus is arranged to form a line of weakness in the plastics sheet.

Suitably, the apparatus comprises conveying means to cause a plastics sheet to travel past a thinning member.

Suitably, the conveying means comprises rollers for engaging the plastics sheet.

Suitably, the conveying means is arranged to cause a plastics sheet to travel at a speed of 0.1 to 2 m s, preferably a speed of 0.5 to 1.5 m more preferably a 0 9 speed of 0.8 to 1.2 m s', for example a speed of about 1 m s.

Suitably, the thinning member is arranged to engage an upper surface of a plastics sheet.

Suitably, the thinning member comprises a grinding member which may grind material from the sheet surface. The grinding member suitably has a rough surface for engaging the plastics sheet. The grinding member may comprise aluminium oxide. The grinding member may comprise a 100 grit to 200 grit, for example a 150 grit material.

Suitably, the thinning member is arranged such that the surface thereof which engages the plastics sheet moves.

Suitably, the thinning member is rotatable.

Suitably, the thinning member comprises a wheel.

Preferably, the thinning member comprises a grinding wheel. Suitably, the axis of the thinning member is arranged to extend substantially perpendicularly to the direction in which the plastics sheet is conveyed.

Suitably, the apparatus is arranged such that, in use, the surface of the thinning member which engages the plastics sheet travels in a counter direction to that in which the plastics sheet is caused to travel.

Suitably, the thinning member comprises a wheel having a diameter of between 10 and 40mm, preferably, between 15 and 30mm, for example of around 22mm. Suitably, the thinning member comprises a wheel having a width of fl 10 between 1 and 10mm, more preferably of between 2 and 5mm, for example of around 3mm.

Suitably, the thinning member is arranged to rotate at a speed of between 5,000 and 20,000 RPM (revolutions per minute), preferably of between 10, 000 and 16,0000 RPM in operation.

Suitably, the apparatus is arranged such that the thinning member is only caused to engage the plastics sheet when the plastics sheet is moving. Suitably, the apparatus is arranged such that the thinning member is automatically brought into engagement with the plastics sheet when the plastics sheet has a speed within an operating range. The apparatus may comprise a detector to determine the speed of the plastics sheet. Suitably, the apparatus is arranged to cause the thinning member to be moving before being brought into contact with the plastics sheet.

Suitably, the apparatus is arranged such that the angle at which the thinning member engages the plastics sheet can be adjusted.

Suitably, the apparatus comprises a moveable head to which the thinning member is mounted. Suitably, the axis of the thinning member is fixedly positioned relative to the head. Suitably the head is tiltable. Suitably, the head comprises a plate.

Suitably, the head comprises a leading edge and a trailing edge, the leading edge lying upstream of the trailing edge relative to the direction in which the plastics sheet travels. Suitably, the head comprises first and second fl 11 side edges extending between the trailing and leading edges. Suitably, the head can be tilted such that the leading edge is raised or lowered relative to the trailing edge. Suitably, the head can be tilted such that the first side edge is raised or lowered relative to the second side edge. Suitably, any corner formed between two adjacent edges of the head can be raised or lowered relative to any other such corner.

The apparatus may thus be arranged to adjust the orientation of the thinning member to compensate for any deviation of the sheet from its desired path as it travels past the thinning member. Accordingly, it may not be necessary to stop a manufacturing line to re-align the sheet should the sheet begin to drift off course.

Instead, the head may be re-aligned to re-align the thinning member and compensate for the sheet drift.

Suitably, the apparatus comprises actuating means for moving the thinning member relative to the plastics sheet.

Suitably, the actuating means is arranged to move the head relative to the plastics sheet.

Suitably, the actuating means comprises an actuator member coupled to the head. Suitably, the head is tiltable relative to the actuator member. Suitably, the actuator member comprises a plate.

Suitably, the apparatus comprises a frame. Suitably, the actuator member is pivotally connected to the frame, preferably hingedly connected.

I

Suitably, the actuator means comprises an actuator arm for moving the actuator member relative to the frame.

Suitably, the actuator arm comprises a pneumatic ram. The actuator arm may have a first end mounted to the actuator member and a second end mounted to a support leg extending from the frame.

Suitably, the apparatus comprises adjustment assemblies for tilting the head. Suitably, the apparatus comprises four adjustment assemblies. Suitably, the apparatus comprises four adjustment assemblies connected to the head in a pattern such that they form the corners of a square.

Suitably, the adjustment assemblies are arranged to tilt the head relative to the actuator member. Suitably, the adjustment assemblies are arranged to connect the head to the actuator member.

Suitably, each adjustment assembly comprises a threaded rod. Suitably a first end of each rod is fixedly positioned relative to the head. Suitably, each rod is moveable relative to the actuator member. Suitably, a threaded knob is mounted to the rod and can be rotated to bear against the actuator member or preferably against a bearer member supported by the rod which in turn bears against the actuator member. In use, rotating the threaded knob such that it moves down the rod towards the actuator member may thus cause the part of the head connected to the rod to be pulled towards the actuator member.

Suitably, the head is biased to move away from the actuator member when, in use, the threaded knob is rotated away from the actuator member. The head may be biased by gravity to move away from the actuator member.

Preferably, the head is biased by a biasing member, for example spring biased, to move away from the actuator.

Suitably, the rod supports a biasing member which suitably comprises a compression spring. The biasing member may interpose abutment members mounted on the rod for engaging the head and actuating member respectively.

The adjustment assembly may also serve as force control/and or shock absorption means. Suitably, only gravity and biasing members restrict movement of the head towards the actuating means. Thus, in use, should the thinning member engage the plastics sheet too forcefully the head may move towards the actuator member compressing one or more of the biasing members. Similarly, movement of the head caused by vibration of the motor and/or external shock may be absorbed by the biasing members.

Suitably, the apparatus further comprises a limit keeper arranged, in use, to limit the movement of the actuator member toward the plastics sheet. The limit keeper may thus limit movement of the head and thus thinning member toward the plastics sheet. Suitably, the limit keeper is arranged to set the amount of material to be removed from the surface of the plastics sheet by the thinning member.

The limit keeper suitably comprises a bracket carrying a screw for making fine adjustments to the limit position which may be defined by the screw end.

Brief description of the drawings

The present invention will now be illustrated by way of example with reference to the accompanying drawings in S which: Figure 1 is a perspective view of an article of packaging in an open configuration; Figure 2 is a perspective view of an article of packaging in a sealed configuration; Figure 3 is a perspective view of an article of packaging which has been breached to open it; Figure 4 is a cross section along line A-A of Figure 1; Figure 5 is a front perspective view of an apparatus for forming a weak portion in a plastics sheet; Figure 6 is a side view of the apparatus of Figure 5 in a non-engagement position; Figure 7 is a side perspective view of the apparatus of Figure 6 in an engagement position; and Figure 8; is a detailed view showing the adjustment assembly of the apparatus in partial cross-section.

Detailed description of the preferred embodiments

As illustrated by figures 1 to 4 an article of packaging 1 comprises a plastics bag 3 formed from first and second 0 15 sheets 5, 7. The first sheet 5 comprises a flap 9 carrying an adhesive strip 11 covered by a backing sheet 13. The sheets 5, 7 are bonded to form sealed edges along 3 sides of the bag 3. Attached to the flap 9 of the first sheet 5 is a paper sheet 15 which can carry information relating to the contents of the bag 3.

The bag has an opening 17 through which, in use, an object (not shown) can be loaded into the bag. The bag can then be closed and sealed by folding the flap 9 over the opening and adhering it to the second sheet 7. To adhere the flap 9 to the second sheet 7 the backing sheet 13 can be peeled from the adhesive strip. The flap 9 can then be pressed against the second sheet 7 to cause the adhesive strip 11 to bond thereto.

The second sheet 7 of the bag comprises a weak portion 19 which comprises a part of the sheet 7 which is thinner than the parts adjacent thereto. The weak portion 19 comprises a line of weakness extending between side edges of the bag 3. The weak portion 19 comprises no apertures and thus is substantially liquid tight.

In use, once the flap 9 is folded over the opening 17 as shown by Figure 2 the bag 3 is substantially liquid tight.

The bag 3 may, in use, serve as a secondary container for a sample, such as a blood sample, contained in a primary container, such as a specimen pot, (not shown) . Thus, should the sample leak from the primary container it may be retained by the bag 3 serving as the secondary container.

In use, to remove an object (not shown) from the sealed bag 3 it is necessary to breach the bag 3. This can be done by pinching the second plastic sheet 7 between a finger and thumb on both sides 21, 23 of a weak portion 19 s and pulling in opposing directions. This may cause the sheet 7 to tear along the weak portion 19 to create an aperture 25 through which an object (not shown) can be removed from the bag.

To produce such bags 3 a first plastics sheet web (not shown) , for forming first sheet 5, is bonded to a second plastics sheet web (not shown), for forming second sheet 7, and a paper sheet web (not shown) , for forming paper sheet 15, is bonded to the first plastics web. The combined webs are then passed through an apparatus 101 for creating a weak portion in the second web.

When the web is passed through apparatus 101 the weak portion 19 of the second plastics sheet 7 is formed by passing the second plastics sheet web (from which the second sheet 7 of the bag is formed) under a grinding wheel to remove material from the surface thereof.

Bags are then formed by sealing the conjoined plastics sheet webs and cutting the conjoined webs at regular intervals.

As illustrated by Figures 5 to 7 an apparatus 101 for creating a weak portion in a plastics sheet, comprises a thinning member 103 arranged to create a thin portion in a plastics sheet web (not shown) The apparatus 101 comprises conveying means (not shown) comprising rollers arranged to convey a plastics sheet web past a thinning member 103 at a speed of around 1 ms1.

The thinning member 103 comprises a rotatable grinding wheel 105 having a surface 107 arranged to engage the plastics sheet web surface to remove material from the sheet surface. In use, the grinding wheel 105 may thus decrease the thickness of the sheet at the parts it contacts and so weaken the sheet. The grinding wheel 105 comprises a 150 grit grinding wheel having a diameter of 22mm and a width of 3mm available from Draper under stock number 62727.

The grinding wheel 105 is mounted on a spindle 109 the axis of which extends substantially perpendicular to the direction (illustrated by arrow B) in which the plastics sheet web is conveyed in use. The grinding wheel 105 is arranged to rotate in the direction illustrated by arrow C. The spindle 109 is mounted to bearings 111 and driven by a motor 113 via a belt 115. The thinning member 103 and motor 113 are mounted to a head 117 comprising a metal plate. The head 117 is tiltable such that, in use, the angle of the thinning member relative to the plastics sheet web can be adjusted.

The apparatus 101 further comprises actuator means for moving the head 117 and thus thinning member 103 relative to the plastics sheet web. The actuating means comprises an actuator member 119 comprising a metal plate.

\.. 1 18 The actuator member 119 is pivotally connected to a frame 121 by hinge 123 at a downstream (relative to the direction in which the plastics sheet web travels) edge 125. The actuator member 119 is connected to an actuator arm 127, comprising a pneumatic ram (operating at a pressure of around 4 BAR) for moving the actuator member relative to the frame 121, adjacent an upstream edge 129 of the actuator member. The actuator arm 127 is connected at a first end to the actuator member 119 and at a second end to a support leg 131 extending upwardly from the frame 121.

The head 117 is mounted to the actuator member 119 by four substantially identical adjustment assemblies 133. The adjustment assemblies 133 are mounted to the head 117 in a pattern which forms the corners of a square and are arranged to allow the head 117 to be tilted relative to the actuating member 119.

Each adjustment member 133 comprises a threaded metal rod having a first end 137 passing through an aperture 139 in the head 117 and fixed in place by a nut 141 and threaded abutment member 143. The rod 135 projects through an aperture 145 in the actuator member 119 such that the rod 135 can move relative to the actuator member 119. A bearer member 147 is located onto the rod 135 with the rod passing through a non-threaded aperture thereof such that it can move relative thereto. The bearer member 147 interposes an upper face of the actuator member and a first threaded knob 149.

In use, the first threaded knob 149 can be rotated to move towards the first end 137 of rod 135 to push the bearer member 147 against the actuator member 119 and then cause the rod 135 to travel relative to the actuator member 119.

The head 117 may thus be pulled towards the actuator member 119. When the first threaded knob 149 is rotated to move away from the first end 137 of the rod 135 gravity can cause the head 117 to move away from the actuator member 119.

The assembly 101 also comprises a second threaded knob 151 arranged, in use, to be rotated along the rod 135 to abut against the first threaded knob 149. This may aid in securing the first knob 149 in place such that it can not be knocked causing the head 117 to move relative to the actuating member 119.

The adjustment assembly 133 further comprises a non- threaded abutment member 153 located onto the rod 135 below the actuating member 119 with the rod passing through a non-threaded aperture thereof such that it can move relative thereto.

Mounted around the rod 135 between the non-threaded abutment member 153 and threaded abutment member 143 is a biasing member comprising a compression spring 155. The spring 155 may assist gravity in biasing the head 117 away from the actuator member 119. As only gravity and the springs 155 hold the head 117 away from the actuating member 119 the head 117 can move away from the plastics sheet web, if the force exerted by the thinning member 103 on the sheet reaches a desired maximum, in order to reduce the risk of the sheet being perforated. The springs 155 may also provide shock absorbing means should the apparatus be knocked in order to protect the sheet from being perforated by the thinning member 103.

The head 117 comprises a leading (upstream) edge 157 and a trailing (downstream) edge 159 which extend generally parallel to the direction in which the plastics sheet web is conveyed. The head has first and second side edges 161, 163 extending between the leading and trailing edges 157, 159.

In use, the length of the rod 135 of each adjustment assembly 133 which lies between the actuating member 119 and head 117 can be adjusted to tilt the head 117. The leading edge can be raised or lowered relative to the trailing edge and the first side can be raised or lowered relative to the second side. Corners of the head can be raised or lowered relative to one another. Thus, the thinning member 103 can be set to engage a plastics sheet at a range of angles. The position of the head 117 may thus be optimised to form a weak portion in the plastics sheet and may be adjusted to compensate for any drift of the plastics sheet web from a preferred path.

The apparatus 101 further comprises a limit keeper 165 (omitted from Figure 5) mounted to the frame 121 and arranged, in use, to limit the movement of the upstream edge 129 of the actuator member 119 toward the plastics sheet web. The limit keeper 165 thus limits movement of the head 117 and thus thinning member 103 toward the plastics sheet web. The limit keeper 165 comprises a bracket 167 carrying a screw 169 for making fine adjustments to the limit position defined by the screw end 171. The limit keeper may provide an element of protection to the plastics sheet and thinning member 103 against an operator over adjusting the adjustment means.

In use, the actuator member 119 and thus head 117 are moveable by the actuator arm 127 between an engagement position (illustrated by Figure 6) in which the thinning member abuts a plastics sheet web and a nonengagement position (illustrated by Figure 7) in which the thinning member is removed from contact with the plastics sheet web.

With the plastics sheet web and the thinning member stationary the actuator member can be moved to the engagement position and the adjustment assemblies 133 can be manipulated to adjust the position of the head 117such that the thinning member 103 engages the plastics sheet at the desired angle and to the desired extent. The actuator member 119 can then be moved to the non-engagement position and the plastics sheet web and thinning member can be caused to move until they are at the desired operating speed. The actuator member 119 can then be automatically moved to the engagement position such that the thinning member 103 engages the sheet and removes material from the surface thereof thus creating a thinner part of the sheet which provides a weak portion.

To allow the thinning member to automatically be moved into engagement with the plastics sheet web only when the machine is up to speed the apparatus is arranged to sense the speed of the web. This is achieved by use of a proximity sensor (not shown) which detects the web speed and converts it to a voltage value upon which two driver stages (not shown) are used to drive an air solenoid (not

C

shown) linked to the pneumatic ram of the actuator arm and to drive the high speed motor. This brings the thinning member up to speed and then into contact with the web.

The solenoid (not shown) used to drive the pneumatic ram comprises 5/2 solenoid (5 port 2 way) spring return valve.

The rate of upward and downward thrust of the actuator arm is controlled using exhaust flow adjusters on the solenoid valve. The thrust is set to produce a gentle upward and downward stroke so as not to produce unnecessary forces on the plastics sheet. The pneumatic ram is not proportionately controlled and is used solely to lower and raise the thinning member onto and off the surface of the web material.

It will be appreciated that preferred embodiments of packaging according to the present invention may provide advantageous means for the transportation of medical samples and may be cost effective to produce.

Attention is directed to all papers and documents which are filed concurrently with or previous to this specification in connection with this application and which are open to public inspection with this specification, and the contents of all such papers and documents are incorporated herein by reference.

All of the features disclosed in this specification (including any accompanying claims, abstract and drawings), and/or all of the steps of any method or process so disclosed, may be combined in any combination, except combinations where at least some of such features and/or steps are mutually exclusive.

Each feature disclosed in this specification (including any accompanying claims, abstract and drawings) may be replaced by alternative features serving the same, s equivalent or similar purpose, unless expressly stated otherwise. Thus, unless expressly stated otherwise, each feature disclosed is one example only of a generic series of equivalent or similar features.

The invention is not restricted to the details of the foregoing embodiment (s) . The invention extends to any novel one, or any novel combination, of the features

disclosed in this specification (including any

accompanying claims, abstract and drawings) , or to any novel one, or any novel combination, of the steps of any method or process so disclosed.

Claims

Claims 1. An apparatus for forming a weak portion in a plastics sheet,

said apparatus comprising a thinning member for engaging a surface of the plastics sheet and means to move said plastics sheet relative to a surface of the thinning member such that a part of the surface of the sheet can be engaged and removed by the thinning member to reduce the sheet thickness and provide a weak portion in the sheet which is thinner than parts of the sheet adjacent thereto.
2. An apparatus according to Claim 1, wherein the apparatus is arranged to form a line of weakness in the plastics sheet.
3. An apparatus according to Claim 1 or 2, wherein the apparatus comprises conveying means to cause said plastics sheet to travel past said thinning member.
4. An apparatus according to any preceding claim, wherein the thinning member is arranged to engage an upper surface of said plastics sheet.
5. An apparatus according to any preceding claim, wherein the thinning member comprises a grinding member.
6. An apparatus according to any preceding claim, wherein the thinning member comprises a wheel.
7. An apparatus according to any preceding claim, wherein the thinning member is arranged such that a surface thereof which engages the plastics sheet moves.
8. An apparatus according to Claim 7, wherein the apparatus is arranged such that, in use, the surface of the thinning member which engages the plastics sheet travels in a counter direction to that in which the plastics sheet is caused to travel.
9. An apparatus according to any preceding claim, wherein the apparatus is arranged such that the thinning member is only caused to engage the plastics sheet when the plastics sheet is moving.
10. An apparatus according to Claim 9, wherein the apparatus is arranged such that the thinning member is automatically brought into engagement with the plastics sheet when the plastics sheet has a speed within an operating range.
11. An apparatus according to any preceding claim, wherein the apparatus is arranged to cause the thinning member to be moving before being brought into contact with the plastics sheet.
12. An apparatus according to any preceding claim, wherein the apparatus is arranged such that the angle at which the thinning member engages the plastics sheet can be adjusted.
13. An apparatus according to any preceding claim, wherein the apparatus comprises a moveable head to which the thinning member is mounted.
14. An apparatus according to Claim 13, wherein the head can be tilted such that a leading edge thereof is raised or lowered relative to a trailing edge thereof.
15. An apparatus according to Claim 13 or 14, wherein the head can be tilted such that a first side edge thereof is raised or lowered relative to a second side edge thereof.
16. An apparatus according to any preceding claim, wherein the apparatus comprises actuating means for moving the thinning member relative to the plastics sheet.
17. An apparatus according to Claim 16 when dependent on any of Claims 13 to 15, wherein the actuating means is arranged to move the head relative to the plastics sheet.
18. An apparatus according to Claim 17, wherein the actuating means comprises an actuator member coupled to the head.
19. An apparatus according to Claim 18, wherein the head is tiltable relative to the actuator member.
20. An apparatus according to Claim 18 or 19, wherein the apparatus comprises a frame to which the actuator member is pivotally connected.
21. An apparatus according to Claim 20, wherein the apparatus comprises an actuator arm for moving the actuator member relative to the frame.
22. An apparatus according to any of Claims 18 to 21, wherein the apparatus further comprises a limit keeper arranged, in use, to limit the movement of the actuator member toward the plastics sheet.
23. An apparatus according to any of Claims 13 to 15 or 17 to 22, wherein the apparatus comprises adjustment assemblies for tilting the head.
24. An apparatus according to Claim 23 when dependent on any of Claims 18 to 22, wherein the adjustment assemblies are arranged to tilt the head relative to the actuator member.
25. An apparatus according to Claim 24, wherein the adjustment assemblies are arranged to connect the head to the actuator member.
26. An apparatus according to Claim 25, wherein each adjustment assembly comprises a threaded rod, a first end of which is fixedly positioned relative to the head and which is moveable relative to the actuator member.
27. An apparatus according to Claim 26, wherein a threaded knob is mounted to the rod of each adjustment assembly and can be rotated to bear against the actuator member or against a bearer member supported by the rod which in turn bears against the actuator member such that, in use, rotating the threaded knob such that it moves down the rod towards the actuator member causes the part of the head connected to the rod to be pulled towards the actuator member.
28. An apparatus according to Claim 27, wherein the head is biased to move away from the actuator member when, in use, the threaded knob is rotated away from the actuator member.
29. An apparatus according to any of Claims 23 to 28, wherein the adjustment assemblies also serve as force control/and or shock absorption means.
30. An apparatus for forming a weak portion in a plastics sheet substantially as herein described with reference to Figures 5 to 8 the accompanying drawings.
31. An article of packaging having a closeable opening and which comprises a plastics sheet having a weak portion to aid tearing of the sheet such that, in use, once closed the packaging may be breached by a user creating an aperture at the weak portion and wherein the weak portion of the sheet is thinner than parts of the sheet adjacent thereto.
32. An article according to Claim 31, wherein the weak portion comprises a line of weakness.
33. An article according to Claim 31 or 32, wherein the weak portion does not comprise any apertures.
34. An article according to any one of Claims 31 to 33, wherein the weak portion is substantially liquid tight.
35. An article according to any of Claims 31 to 34, wherein the article of packaging is sealable to provide a substantially liquid tight package.
36. An article according to any of Claims 31 to 35, wherein the article comprises a plastics bag.
37. An article according to any of Claims 31 to 36, wherein the plastics sheet is manufactured with substantially the same thickness throughout its extent and the weak portion is formed by subsequently reducing the thickness of a part of the plastics sheet.
38. An article of packaging substantially as herein described with reference to Figures 1 to 4 the accompanying drawings.
39. A method of manufacturing a product comprising a plastics sheet having a weak portion, which weak portion can aid tearing of the sheet in use and is thinner than parts of the sheet adjacent thereto and wherein the sheet is manufactured with substantially the same thickness throughout its extent and the weak portion is formed by subsequently reducing the thickness of a part of the sheet.
40. A method according to Claim 39, wherein the method comprises a method of forming articles of packaging according to any of Claims 30 to 38.
41. A method according to Claim 39 or 40, wherein the method comprises forming products comprising bags which comprise first and second plastics sheets and have a paper sheet attached thereto.
42. A method according to any of Claims 39 to 41, wherein the method comprises conjoining a first plastics sheet web and a paper sheet web.
43. A method according to any of Claims 39 to 42, wherein the method comprises conjoining first and second plastics sheet webs.
44. A method according to Claim 43, wherein the method comprises forming cuts in the conjoined webs to create a plurality of products each comprising a bag.
45. A method according to any of Claims 39 to 44, wherein the method produces a weak portion which is substantially liquid tight.
46. A method according to any of Claims 39 to 45, wherein the method comprises causing a plastics sheet to move relative to a surface of a thinning member such that a part of the surface of the sheet is engaged and removed by the thinning member to reduce the sheet thickness and provide a weak portion.
47. A method according to any of Claims 39 to 46, wherein the method comprises causing a plastics sheet to travel past a thinning member.
48. A method according to Claim 46 or 47, wherein the method comprises causing a surface of said thinning member which engages the plastics sheet to travel in a counter direction to that in which the plastics sheet is caused to travel.
49. A method according to any of Claims 39 to 48, wherein the method employs an apparatus according to any of Claims 1 to 30.
50. A method substantially as herein described.