Patent Publication Number: US-3881041-A

Title: Medium for heat bonding

Description:
United States Patent [1 1 Glienke 1 1 Apr. 29, 1975 [54] MEDIUM FOR HEAT BONDING 2.411.328 11/1948 MacNab 33/12 2.657.159 10/1953 Nahman 2/243 R [75] Inventor: Peter Otto Gllenke. Baden-Baden. 3091649 7H9 wightwickw 7/3.: Germany 3.097.364 7/1963 Hess 2/243 R 3.127.303 3/1964 Neuhauscr.... 161/146 [73] Asslgnee&#39; 23:32:21: n 3.168.749 2/1965 Cala 2/243 R e 3 3.383.345 11/1966 Berck i i i 4 161/406 22 Filed; Ju|y 2 973 3.328.809 7/1967 Payne et a1. 161/406 3.383.263 5/1968 Slorti 156/234 [21] Appl. No.: 382,875 3.741.786 6/1973 Torrey 161/406 3.785.014 1/1974 Cancpa 161/167 {30] Foreign Application Priority Data Aug. 2. 1972 German 2237923 &#34;&#34;&#39;i&#34; F&#39; Lesmes Ass/stun! Exunum&#39;r.l. Cannon 52 us. Cl. 428/40; 2/243; 2/269; Darby Cushman Int. Cl...... A4ld 27/10; B3211 3/06; B32b 7/14 Field of Search 2/243. 269. 275; 38/144; 117/112. 3.4. 45. 76 A. 122 H. 122 R122 PB; 156/234. 235, 239. 240; 161/146. 147, 167. 410. 406, 406 T References Cited UNITED STATES PATENTS 2/1940 Bennett 11713.2  
 {57] ABSTRACT A medium for effecting heat bonding between two surfaces of material comprising a carrier sheet one side of which carries layers of a heat bonding sub stance and ofa pressure sensitive adhesive. such layers being arranged that the both present exposed surfaces.  
 16 Claims, 10 Drawing Figures PMENTEDAPRZS I975 SHEET 10F 2 FIG3 MEDIUM FOR HEAT BONDING This invention relates to a novel medium for effecting heat bonding, more particularly for joining together su perposed surfaces of textile or other sheet materials.  
  The traditional method of such joining has been by means of sewing with sewing thread. Thus, this has been the traditional method of joining together two sheets of materials by means of a sewn seam. it has also been used for strengthening or selvedging the edge of materials by turning back the edge of the material on itself and sewing the hem thus formed. Patches have also been applied to materials by sewing, e.g., for decoration, strengthening or repairing.  
  Attempts have been made to achieve such joining by means of the use of heat bonding substances (for exam plc the so-called hot melt adhesives I, so as to avoid the complication and labour of sewing with sewing thread. This has involved, for example, the application of a layer of heat bonding substance between the pieces of material to be joined. and then applying heat, e.g.. by means of an iron. to melt the heat bonding substance and so join the two pieces of material together.  
 In order to facilitate the correct positioning of the heat bonding substance, a prime method has been tirstly to heat bond or adhere the layer of heat bonding substance to one piece of material along the line of the required seam then to superpose the other piece ofmaterial exactly in place, and then to apply heat to bond the assembly together.  
  A prime difficulty has been to find a convenient, effective and economical medium and manner for performing this bonding method, which will ensure that the heat bonding substance will he firmly held in the required position against the material prior to heat bonding being effected; while at the same time allowing the operator to remove and re-apply the bonding substance prior to heat bonding if it has been incorrectly laid. It is also important to avoid stretching or tearing of the layer of heat bonding substance during these operzu tions.  
  It is the object of the present invention to solve these difficulties by the provision of a medium which is economical to produce and convenient for the user to harm dle and use.  
  According to the present invention, a medium for effecting heat bonding between two surfaces of material comprises a carrier sheet one side of which carries lay ers ofa heat bonding substance and of a pressure sensitive adhesive, such layers being arranged that they both present exposed surfaces.  
  In operation, the user can press a strip ofthis medium against one portion of material, along the line of the proposed seam. The adhesive will stick to the material and hold the strip in position. The adhesive will also allow the user to remove and replace the strip if correct positioning is found not to have been achieved at the first or subsequent attempts. Due to the carrier, the layer or layers or the heat bonding substance will not be stretched or torn. Heat is then applied to melt the heat bonding substance and bond it to the material. The carrier sheet can then be removed (with or without the adhesive according to the two main embodiments of the invention to be described), leaving the heat bonding substance on the material. The other portion of material is then applied over the heat bonding substance, and heat is again applied to melt the latter and achieve a firm bond between the superposed surfaces of material.  
  in a first embodiment of the invention. the arrangement is such that only the heat bonding substance is transferred to the first portion of material. and the adhesive is so preferentially adhered to the carrier sheet that it is pulled away from the material with the carrier sheet. This has the advantage of providing a ready means of removing the adhesive. if it is not desired to have the adhesive in the resultant ioint. ()n the other hand, there is then no pressure sensitive adhesive to assist in the holding of the other portion of material until the linal heat bonding is effected.  
  This first embodiment is suitably constructed by coating the said one side of the carrier sheet with a layer of pressure sensitive adhesive and applying the heat bonding substance over part of the layer of pres sure sensitive adhesive. It is ensured that the adhesive has such a strong affinity for the carrier sheet (cg. by giving the carrier sheet a roughened surface or preliminary coating of primer] that the adhesive will have a greater adherence to the carrier sheet than to the material. It is found that the heat bond to the heat bonding substance to the material will normally be sufficient to pull the heat bonding substance away from the carrier sheet upon removal of the latter from the material.  
  in a second and preferred embodiment of the invention, the arrangement is such that the adhesive is transferred to the material with the heat bonding substance. The adhesive is then available on the material to assist in the holding of the other portion of material. Thus. the adhesive on the one side of the carrier sheet is utilizable to serve a holding function against both portions of material, which is a substantial economy. If desired it may be contrived that the adhesive is dissolved out of the material after the joint has been formed.  
  This second embodiment requires that the surface of the carrier sheet has less affinity for the adhesive than the material, which can for example be ensured by coating the carrier sheet with a silicone or other release coat. The area of the carrier sheet covered by the heat bonding substance will normally be distinct from that covered by the pressure sensitive adhesive, i.e., there will normally be no overlapping of the respective layers as may be provided in the first embodiment. The purpose of this feature is to ensure that the full area of the heat bonding substance is available for contact with the said other portion of material, though this feature is not so important if the adhesive becomes miscible with the heat bonding substance during the heating.  
  Whichever embodiment is used, it is preferred that the heat bonding substance be provided in discontinuous layers covering numerous substantially separate areas of the carrier sheet. c.g., in the form of dots. It is found that this, rather surprisingly, creates a stronger bond against forces tending to part the two portions of material which have been heat bonded together. If a continuous layer of heat bonding substance is used. one finds that, once such forces have started to lift a portion of such layer away from a portion of material, it can be somewhat easier to lift away the remainder ofthe layer. With discontinuous layers, this operation has to be individually started&#34; for each dot or other portion of the heat bonding substance, and the bond becomes analogous to spot welding. Discontinuous layers of course also provide the advantage of economy in the quantity of substance used.  
  It c. n be advantageous to provide the adhesive also in such dots or other discontinuous layers.  
  Alternatively, the layers of heat bonding substance and/or adhesive can be provided in the various other forms shown in the accompanying drawings. to be described hcreinbelow.  
  It is found that. unless the adhesive is miscible with the heat bonding substance, the adhesive can have a deleterious effect on the heat bonding substance if the two are permitted to have contact with each other. To avoid this, it is preferred that the heat bonding sub stance be laterally separated from, and out of contact with, the pressure sensitive adhesive.  
  The exposed surface of the pressure sensitive adhesive is suitably covered by a readily removable protective sheet. This may be provided by the reverse side of the carrier sheet, when such sheet is rolled up. For this purpose, the reverse side of the carrier sheet may be coated with a silicone or other release material.  
  The term heat bonding substance is used herein to denote any substance, normally a polymer, which is capable of effecting the bonding of materials under the action of heat. The bonding is normally effected by an actual melting of such substances, which may be any of the substances commonly known as hot melt adhesives. Useful heat bonding substances include for example polyamides, polyamide copolymers, polyurethanes and polyacrylates.  
  The carrier sheet can be of any suitable material for the particular purpose, e.g., paper which can be impregnated, coated or otherwise treated to give it the required properties.  
  The invention is illustrated in the accompanying drawings, in which:  
  FIG. 1 is a cross-section of an example of the said first embodiment, in a first working stage;  
  FIG. 2 illustrates the embodiment shown in FIG. 1, after the seam joint has been made;  
  FIGS. 3 to 7 illustrate various constructions of the type of embodiment shown in FIG. 1, in elevation-and cross-section;  
  FIG. 8 illustrates an example of the said second embodiment, in a first working stage;  
  FIG. 9 illustrates the embodiment shown in FIG. 8 after the joint seam has been formed, and  
  FIG. 10 illustrates a preferred example of the embodiment illustrated in FIG. 8.  
  In FIG. 1 can be seen a layer of material, in this case a web of fabric 1, the cut edge of which is designated 2. This embodiment of the invention will be explained below with reference to providing this material I with a hem.  
  The joining medium comprises a carrier sheet 3, for example a paper having a rough surface, a layer 4 of pressure sensitive adhesive applied thereto, and a film 5 of heat bonding substance which in turn is applied to the adhesive layer 4. This joining medium is laid on the fabric web 1 at a distance from the cut edge 2 corresponding to the desired width of hem and, when subjected to slight pressure, adheres by means of the adhesive layer 4. The adhesive itself has greater affinity for the carrier layer 3 than for the fabric web 1. The joining medium applied and adhesively secured in this manner is then ironedv This causes the film 5 to melt and the film penetrates at least partly into the web 1, without however passing through the latter. The carrier sheet 3 is then peeled off, together with the adhesive layer 4 adhering to it, from the fabric web 1. On the other hand, the film 5 bonded in position remains adhering to the fabric web 1. The latter is then turned over to the width of the hem and laid over the film 5, as can be seen in FIG. 2. By means of normal ironing the film 5 is then re melted and bonds together the hem, which now comprises two layers, in the region indicated by crosses and designated 6.  
  FIG. 3 illustrates essentially the same example in which the carrier sheet 13 is in the form of a strip. A layer of adhesive 14 is applied to this carrier sheet, and to the layer 14 a film 15 of heat bonding substance is applied. The film 15 has a smaller width than the carrier sheet 13, so that the adhesive layer 14 projects at the edge and is exposed for the purpose of application.  
  A similar example is illustrated in FIG. 4. An adhe sive layer 24 is once again applied to a carrier sheet 23, which is in strip form. The film 25 is in this case of zigzag shape, so that it imitates the conventional seam form.  
  In the example illustrated in FIG. 5, the width of the carrier sheet 33 and that of the film 35 coincide with one another. The film 35 however is provided with cut&#39; outs 36. The adhesive layer 34 lies under the film 35 and is exposed through the cutouts 36.  
  Whereas in the examples described above the heat bonding substance is of geometrically regular form, in the example illustrated in FIG. 6 an irregular form is selected. An adhesive layer 44 is once again applied to the carrier sheet 43. The heat bonding substance in this case is in the form of a web of non-woven fibres 45 which are irregular and are disposed at irregular distances from one another. The adhesive layer 44 is exposed between the fibres.  
  In FIG. 7 on the other hand a regular shape is once again selected for the heat bonding substance, but this time in discontinuous layers applied to the adhesive layer 54 which is coated on the carrier sheet 53. The example illustrated shows the heat bonding substance in rectangular portions, which are disposed in columns spaced a short distance apart. The carrier sheet 53 may if desired be provided with perforations 56, by means of which it can be divided into narrow strips.  
  FIGS. 8 and 9 illustrate the said second embodiment of the invention and show a similar illustration to that in FIGS. 1 and 2. A web of fabric 61 having a cut edge 62 is shown, and this web is once again to be hemmed. In order to produce the hem seam, use is made of a joining medium, which consists of a carrier sheet 63, two strip layers 64 of a pressure sensitive adhesive, and a strip layer of hot melt adhesive spaced from the adhesive strips. The carrier sheet 63 may be a coated or impregnated paper the affinity of which for the adhesive 64 is less than the affinity of the latter for the fabric web 61.  
  After application of the joining medium, which adheres to the fabric web 61 through the adhesive layers 64, and after the first ironing, the layer 65 melts and partly penetrates into the fabric web 61. The carrier sheet 63 is then lifted off in accordance with the dotand-dash lines shown while the transfer adhesive 64, which is for the most part transferred by the action of pressure, and also the layer 65 remain adhering to the fabric web 61. Consequently, only the carrier sheet 63 is removed. The fabric web 61 is then folded over and ironed again, whereby the layer 65 is re-melted in the region 66 indicated by crosses, and thus the joining seam is produced. The adhesive layers 64. which during the first ironing operation were likewise transferred to the bottom layer of fabric. remain adhering in the region of the seam. The chemical or physical properties of the transfer adhesive 64 may be so selected that the adhesive is dissolved during the first washing or cleaning operation.  
  FIG. illustrates a preferred embodiment of the example illustrated in FIGS. 8 and 9. Portions 74 of a transfer adhesive. in the form of adhesive dots. and also portions 75 of heat bonding substance in the form of welding dots are applied to a carrier sheet 73. for example of silicone paper. A uniform grid pattern. which can be produced in a simple manner by the screen printing method or the like. is selected for this purpose. This form of medium can naturally also be produced in larger webs and be separated into strips by means of suitable perforations.  
  The heat bonding substance can be applied in the form of layers of particles (bonded or sintered together) instead of in film form. and such is indeed preferred for the examples of FIGS. 8-10.  
  The above description shows that the invention is capable of many modifications. so that it is possible for only a few selected examples to be described. Welding by ironing may naturally also be replaced by other methods. such as contact. impulse, high frequency. or supersonic welding. optionally with the additional application of pressure.  
 What we claim is:  
  l. A medium for effecting heat bonding between two surfaces of textile fabric material comprising a carrier sheet one side only of which carries layers of a heat bonding substance and of a pressure sensitive adhesive, such layers being arranged that they both present exposed surfaces in a plane substantially parallel to the carrier sheet, the surface carrying the heat bonding substance being such that the heat bonding substance is readily transferable therefrom to the surface of the fabric material to be bonded.  
  2. A medium as claimed in claim 1 wherein the heat bonding substance is provided in discontinuous layers covering numerous substantially separate areas of the carrier sheet.  
  3. A medium as claimed in claim 1 wherein the area of the carrier sheet covered by the heat bonding substance is distinct from that covered by the pressure sensitive adhesive.  
 4. A medium as claimed in claim 2 wherein the pressure sensitive adhesive is also provided in discontinuous layers over numerous substantially separate areas of the carrier sheet not covered by the heat bonding substance.  
  5. A medium as claimed in claim 2 wherein the discontinuous layers referred to are in the form of dots.  
  6. A medium as claimed in claim 1 wherein the heat bonding substance is laterally separated from. and out of contact with. the pressure sensitive adhesive.  
  7. A medium as claimed in claim I wherein the heat bonding substance and the pressure sensitive adhesive are miscible with each other and have at least some contact with each other on the carrier sheet.  
  8. A medium as claimed in claim I wherein the surface of the said one side of the carrier sheet carrying the said layers is such that the said layers may readily be transferred therefrom to the surface of the material to be bonded.  
  9. A medium as claimed in claim 8 wherein the said one side of the carrier sheet has a coating of a release material under said layers.  
  10. A medium as claimed in claim 1 wherein the said one side of the carrier sheet is coated with a layer of the pressure sensitive adhesive and the heat bonding substance is applied over part of the layer of pressure sensitive adhesive. the pressure sensitive adhesive having such a strong affinity for the surface of the carrier sheet that it will remain adherent to the carrier sheet after transfer of the heat bonding substance to the surface of the material to be bonded.  
  11. A medium as claimed in claim 10 wherein the heat bonding substance and the pressure sensitive adhesive are miscible with each other.  
  12. A medium as claimed in claim 1 wherein at least the exposed surface of the pressure sensitive adhesive is covered by a readily removable protective sheet.  
  13. A medium as claimed in claim 12 wherein the other side of the carrier sheet constitutes the readily removable protective sheet when the carrier sheet is rolled up.  
  14. A medium as claimed in claim 13 wherein the said other side of the carrier sheet is coated with a release material.  
 15. A medium as in claim 1, wherein the carrier is paper.  
 16. A medium as in claim 1, wherein the heat bonding substance is a hot melt adhesive.  
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