A FOLDER

Abstract: A folder for thermal binding, the folder having a channel shaped spine containing hot melt adhesive, the spine being formed from a resilient plastics sheet material.

Description: A FOLDER The present invention relates to a folder for use in thermal binding. In particular, the present invention relates to such a folder formed from a flexible resilient plastics sheet material. Thermal binding of a stack of papers into a folder is a convenient method for an end user to produce bespoke books or pamphlets. Thermal binding folders are made of paper or light card and have a spine contøming a strip of hot melt adhesive. Such folders tend not to be very durable or have a long life expectancy, since due to their fibrous nature, they can be easily torn or creased and separation of the bound papers from the folder can occur due to delarnination of paper or card from which the folder is formed. The delarnination problem increases with an increase in the width of the spine. In an attempt to overcome this problem, it is known to embed within the hot melt adhesive a layer of linen in order to provide additional resistance against delarnination. It is therefore desirable to provide a thermal binding cover which is durable, (ie. provides a bound folder which is resistive to tearing) and which is also capable of securely retaining the stack of bound papers for a long period of time. According to one aspect of the present invention there is provided a folder for thermal binding, the folder having a channel shaped spine containing hot melt adhesive, the spine being formed from a resilient plastics sheet material. According to a preferred embodiment of the present invention there is provided a folder including a spine to which front and rear cover sheets are connected, the spine, front and rear cover sheets being integrally formed from a resilient sheet plastics material, the spine being formed to define a channel having a bottom wall and opposed side walls, the front and rear covers being connected by respective fold-lines to upper edges of the side walls of the channel to define hinge connections, a hot melt adhesive located within the channel, the hot melt adhesive extending along the bottom wall and preferably at least partially along the side walls, said fold-lines being formed to substantially remove the inherent resilient bias of the sheet material about said hinge connections. Preferably the channel is formed by folding the sheet material, the plastics material being adapted, for example by heat treatment, to retain me channel shape. Preferably the hot melt adhesive is fused with the plastics material of the spine so as to provide a strong bond between the hot melt adhesive and said plastics material. Preferably to achieve fusing of the hot melt adhesive to the spine, the hot melt adhesive is applied to the spine at a temperature in excess of the softening temperature of the hot melt adhesive. Preferably the hot melt adhesive has a softening temperature of about 140°C and is applied to the spine at a temperature of about 170°C. According to another aspect of the present invention there is provided a method of producing a thermal binding folder the method including the steps of: (i) forming said cover from a resilient plastics sheet so as to define a spine to which front and rear cover sheets are integrally connected, the spine being formed to define a channel having a bottom wall and opposed side walls, (ii) the formation of the spine being performed such that the memory of the plastics material forming said sheet is changed to a modified memory position which retains said channel shape, (iii) applying molten hot melt adhesive into said channel at a first elevated temperature so as to cover the bottom wall and preferably extend at least partially up said opposed side walls, and (iv) cooling said molten hot melt adhesive so as to avoid changing said modified memory position of the plastics material forming the spine. According to another aspect of the present invention there is provided a method of producing a bound book having a folder as defined above containing a plurality of pages, the method including producing the folder as defined above, placing a stack of sheets into the folder with one edge of the stack located within the channel defined by the spine, applying heat to the spine at a second elevated temperature in order to cause softening of the hot melt adhesive, the hot melt adhesive at said second elevated temperature being capable of adhering to the individual sheets comprising said stack, controlling application of heat at said second elevated temperature so as to avoid changing said modified memory position. Preferably said first elevated temperamre is chosen so as to cause surface fusing between the hot melt adhesive and said plastics material forming the spine and said second elevated temperamre is chosen to be less than said first elevated temperature such that softening of the hot melt adhesive at said second elevated temperamre does not affect the fused connection between the hot melt adhesive and the spine. Various aspects of the present invention are hereinafter described with reference to the accompanying drawings in which :- Figure 1 is a schematic perspective view of a folder according to the present invention filled with bound papers; Figure 2 is a plan view of the folder of Figure 1 prior to binding. Referring to the drawings there is shown a folder 10 formed from a sheet of resilient plastics material so as to include a spine 12, a front cover sheet 14 and a rear cover sheet 16. The spine 12 is formed to define a channel 18 having a bottom wall 19 and opposed side walls 20, 21. The spine 12 is preferably formed by folds 22, 23, 24 and 25 to define the channel 18. Folds 22 and 25 also define hinge connections by which rear and front cover sheets 16, 14 are connected to upper edges of side walls 20, 21 respectively. The spine 12 is formed by folding the sheet material about folds 23 and 24 and during the folding process changing the memory of the plastics so as to retain the channel shape. The thus formed channel is subsequently filled with hot melt adhesive 28. Preferably the adhesive 28 fills the channel so as to cover the bottom wall 19 and extend at least partially upwardly opposed side walls 20, 21. In this way, after the hot melt adhesive has set, it assists in restraining the sheet material from bending about folds 23, 24 and assists the spine to maintain its channel shape and helps render the spine relatively rigid. Preferably the folds 24, 25 and 22, 23 are spaced apart by a relatively short distance to define the height of the opposed side walls 20, 21. For example the height of side walls 20, 21 is preferably between 1 to 10 mm, more preferably is about 5 mm and helps resist deformation of the channel sides by bending in use. The height of the opposed sides is preferably the same irrespective of the width of the channel bottom 19. In order to provide a strong bond between the hot melt adhesive 28 and the spine, the hot melt adhesive is preferably applied at a first elevated temperamre which is sufficiently high to cause at least partial fusing between the contacting surfaces of the spine and the hot melt adhesive. Application of the hot melt adhesive at the first elevated temperamre is controlled such that the memory of the plastics material is not changed. To achieve this control, the spine is cooled rapidly immediately after application of the hot melt adhesive. This restricts fusing to the surface region of the plastics material forπ ng the spine and prevents the temperamre triroughout the plastics material rising to a sufficient level to cause softening and changing of memory of the material. Preferably when the folder 10 is to be used in conjunction with a thermal binding machine having a flat hot plate, the folds 23,24 are formed such mat the outer face 19a of the bottom wall 19 is substantially flat, ie. the folds 23,24 do not project outwardly beyond the face 19a. In this way, during the thermal binding process, the outer face 19a is able to sit in face to face contact with the hot plate of the thermal binding machine and thereby ensure rapid heat transfer from the hot plate to the hot melt adhesive in the channel. Folds 22, 25 are formed so as to substantially remove the inherent resilient bias of the sheet material. This enables the respective rear and front covers to be hingedly moved about their respective folds without unduly distorting the relatively rigid spine. Accordingly the spine maintains its shape and is not adversely distorted by movement of either the front or rear cover sheet about their respective folds prior to binding. The sheet plastics material is preferably a thermal plastics capable of retaining a memory position such as polypropylene, or polyethylene, other suitable plastics materials are polystyrene, a polyester or rigid polyvinylchloride. Co-polymers of the above plastics materials may be used. The thickness of me sheet material preferably ranges from about 300μ up to 2000μ. It is envisaged that the channel of the spine may be formed by heat deformation techniques in which case folds 23, 24 would be omitted. Preferably the hot melt adhesive used in connection with polypropylene is based upon an ethylene vinyl acetate co-polymer. With such a combination, the molten hot melt adhesive is preferably applied to the spine at a temperamre of about 170 °C. Binding of sheets into a folder 10 to form a bound book 30 having pages 31 is achieved by taking a stack of sheets and locating the stack within the folder 10 such that an edge of the stack is located within the channel 12a. The filled folder 10 is then placed in a thermal binding machine (not shown) and the hot melt adhesive 28 is heated to a second elevated temperamre (ie. a binding temperamre) at which it softens and penetrates the sheets so as to bond thereto. The second elevated temperamre is selected to be lower than the first elevated temperamre so as not to affect the fused bond between the hot melt adhesive and the spine. Accordingly a strong bond is maintained between the hot melt adhesive and the spine. In addition, the second elevated temperamre is controlled so as not to affect the memory of the plastics material forming the channel 18. In this way, after completion of the binding process, the plastics material forming the spine 12 maintains its memory for retaining the shape of the channel 18. The bound spine 12 thereby has opposed side walls 20, 21 which are restrained from moving about folds 23,24 and so is relatively rigid, ie. the side walls of the spine tend to maintain their positions relative to the bottom wall 19 irrespective of the amount by which the cover sheets 14,16 or pages 31 are moved in during opening of the book and there is only a slight bending of the spine primarily within the region of the bottom wall 19. The choice of plastics material for the spine, its sheet thickness and the hot melt adhesive are preferably chosen to permit said slight bending of the bottom wall 19 as this enhances the durability of the bound book. Absolute rigidity of the bottom wall of the spine is not preferred. In view of the channel 18 mamtaining its shape during repeated opening/closing actions, the marginal portions of the page sheets are protected from excessive folding and so fibrous sheets such as paper, or even coated paper, maintain their integrity in the region of the spine and so can be successfully retained. In this respect, books having a spine width up to about 25 mm and containing dividing sheets of 350 gsm board having been successfully bound. With the example given above wherein the plastics sheet is polypropylene and the adhesive is an ethylene vinyl acetate co-polymer, the second elevated temperamre is preferably about 140°C. With the thermal binding folder of the present invention, it is possible to bind sheet materials to form a permanently bound book. Such books could be used for example as registers for recordal of permanent information. Heretofore, such books have only been produced by traditional stitch binding techniques. In the above example, the hot melt adhesive is elevated to its binding temperamre by heat conduction from a hot plate thermal binding machine. It is envisaged that other means for heating the hot melt adhesive may be used. For example, the hot melt adhesive may contain metal particles and be exposed to an electrical field so as to be heated by induction. Alternatively a hot melt adhesive responsive to ultraviolet radiation may be used.

Claims: CLAIMS 1. A folder for thermal binding, the folder having a channel shaped spine containing hot melt adhesive, the spine being formed from a resilient plastics sheet material. 2. A folder according to Claim 1 including front and rear cover sheets formed from said plastics sheet material and integrally formed with the spine, the spine being formed to define a channel having a bottom wall and opposed side walls, the front and rear covers being connected by respective fold-lines to upper edges of the side walls of the channel to define hinge connections, a hot melt adhesive located within the channel, the hot melt adhesive extending along the bottom wall and preferably at least partially along the side walls, said fold-lines being formed to substantially remove the inherent resilient bias of the sheet material about said hinge connections. 3. A folder according to Claim 2 wherein the channel is formed by folding the sheet material and changing the memory of the plastics to retain the channel shape. 4. A folder according to Claim 3 wherein the bottom wall of the spine is formed to have a flat outer face capable of face to face contact with an opposed flat surface. 5. A folder according to Claim 2, 3 or 4 wherein the height of each of the opposed side walls of the channel is between 1 to 10 mm, preferably about 5 mm. 6. A folder according to any of Claims 1 to 3 wherein the hot melt adhesive is fused with the plastics material of the spine so as to provide a strong bond between the hot melt adhesive and said plastics material. 7. A folder according to any of the preceding claims wherein the plastics material forming the spine is polyvinylchloride and the hot melt adhesive has a softening temperamre of about 140 °C. 8. A method of producing a thermal binding folder, the method including the steps of: (i) forming said cover from a resilient plastics sheet so as to define a spine to which front and rear cover sheets are integrally connected, the spine being formed to define a channel having a bottom wall and opposed side walls, (ii) the formation of the spine being performed such that the memory of the plastics material foraiing said sheet is changed to a modified memory position which retains said channel shape, (iii) applying molten hot melt adhesive into said channel at a first elevated temperamre so as to cover the bottom wall and preferably extend at least partially up said opposed side walls, and (iv) cooling said molten hot melt adhesive so as to avoid changing said modified memory position of the plastics material forming the spine. 9. A method of producing a bound book having a folder according to any of Claims 1 to 7 and containing a plurality of pages, the method including producing a folder according to the method of Claim 8, placing a stack of sheets into the folder with one edge of the stack located within the channel defined by the spine, applying heat to the spine at a second elevated temperamre in order to cause softening of the hot melt adhesive, the hot melt adhesive at said second elevated temperamre being capable of adhering to the individual sheets comprising said stack, controlling application of heat at said second elevated temperamre so as to avoid changing said modified memory position.

Inventors: MORT ROSEMARY, TOWNSEND GLENN, MORT, ROSEMARY, TOWNSEND, GLENN
Applicants: EASIBIND LTD, MORT ROSEMARY, TOWNSEND GLENN, EASI-BIND INTERNATIONAL LIMITED, MORT, ROSEMARY, TOWNSEND, GLENN
Application year: 1998
Main classification: B42D3
IPC codes: B42D3