DIGICON: Novel technologies for rapid prototyping and assembling of high-tech textiles

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1 DIGICON: Novel technologies for rapid prototyping and assembling of high-tech textiles Alexandra De Raeve Joris Cools University College of Ghent Faculty of Technology Ghent, Belgium ABSTRACT The European fashion industry is well established in terms of product quality, productivity, innovation and creativity. Despite increasingly fierce global competition and significant relocation of manufacturing to low-wage countries it continuous to be of considerable importance to Europe s industry. Competitiveness of the clothing and fashion industry in Europe, which is dominated by small and medium-sized enterprises (the average company is family owned and employs 20 people), should come from innovative performance-enhanced sustainable products and processes and not from strategies that rely on quotas and protectionist legislation. Therefore the clothing and fashion industry is in need of more flexible small batch oriented manufacturing processes that allow assembling high tech textiles and a better consumer orientation (mass customization) as well as the computerization of the development and production processes and the information flow. 1. INTRODUCTION The project aims at major changes in the current situation: Realising a breakthrough in the development of an alternative, digital joining technique with commercial available equipment by assembling a print/spray head on a new single-ply cutter to apply adhesives. Optimizing the computerisation of product development, customer management, planning, logistics, production, follow-up and distribution by integrating CAD-CAM, PDM, 3D-bodyscan, within the enterprise resource planning (ERP) This will allow apparel and other assembled materials to become engineered & personalised solutions. 2. EXPERIMENTAL PROCEDURES 2.1. TEST MATERIALS An extensive study of literature and market research provided three types of adhesives which are extensively being tested: 1. Synthetic polymer (polyolefine) based hotmelts 2. Water-based and anionic stabilized polyurethane dispersions Materials + Technology 1

2 3. Aqueous dispersions of polyamide, polyester or polyurethane powder (pastes) These adhesives are being tested on a wide range of different substrates with or without a PUor PVC-coating and with or without a fluor-carbon finish: polyester (micro), polyamide (micro), polyacrylnitril, polyolefines, viscose, polyamide-imides (aramide), glass fibre, cotton and different fibre blends. These substrates are currently being used for various applications such as medical clothing, work wear, fire-fighter clothing, rain- and winter clothing, parasols, tenting, sun protection screens, lingerie, automotive... Substrates with very low surface tension need to be pre treated with plasma or corona. Mixing the adhesive with a cross linking agent improves the durability APPLICATION METHODS As mentioned, the main objective of this research is to combine the cutting of the fabrics and the application of the adhesive in one single process. Therefore a CAD/CAM operated print/spray-head will be mounted on a single-ply cutter. The process is carried out as follows: Figure 1: Gerber single-ply cutter DCS-1500 A pattern part is made up of many lines and points, such as cut lines, seam lines, notches, drills, direction line, text... (see figure 2). All these marks are needed to give proper commands to the cutter. Figure 2: Example of patterns on CAD-software Step 1: The CAD-operator adds additional lines (glue lines) on the pattern. The parameters of the CAM-software will be set accordingly so the systems recognizes these lines as a glue lines. The software gives commands to the cutter and the print/spray head starts applying the adhesive to the substrate. The lead-time will depend on the size and complexity of the pattern(s) and the viscosity of the adhesive. The estimated lead-time is between 3 and 5 minutes. Figure 3: step 1 applying adhesives Materials + Technology 2

3 Step 2: Depending on the type of adhesive used, a drying stage needs to be implemented in the process. Hotmelt adhesives dry when cooling down, meaning the drying process can be skipped. Water-based adhesives need to be dried by an IR- heater. Estimated lead-time: 5 to 10 minutes. Figure 4: step 2 drying the adhesives Step 3: When the adhesive is no longer tacky, the pattern parts can be cut (with a wheel knife or a drag knife) and marked with notches, drills, labels,... The lead-time will depend on the size and complexity of the pattern(s), but is maximum 4 to 5 minutes. Figure 5: step 3 cutting the pattern parts Step 4: When all parts are cut, these can be removed from the table and stored on shelves or trolleys or in boxes for dispatch to the production plants. In the production plants the parts can be assembled by reactivating the adhesive with heat (90 C 180 C, depending on the kind of adhesive) and pressing the layers together with pressure (about 45 psi). The assembling is carried out by means of a conventional taping machine 2.3. ADVANTAGES Stronger seams for needle holes are avoided Shortened lead-times for cutting and applying adhesives Waterproof seams Lighter weight garments by excluding threads and seam sealing tapes Increased flexibility and cost control Faster innovation in products, processes and concepts Creation of more added values 2.4. RESULTS AND PLANNING 8 different adhesives were tested on 30 different substrates. The adhesives were applied to the substrates without prior surface treatment of the fabrics Materials + Technology 3

4 with plasma or corona. The test results underneath represent a comparison of the seam strength between a stitched seam and a glued seam. All the tests were performed under the same conditions on a Lloyd LR 50K materials testing machine with a constant rate of extension (CRE) of 10 mm/minute. The test method was according NEN-ISO (grab test). The stitched seams were stitched with a polyester thread tex 120 and with 5 stitches per cm, and were tested in dry condition. The glued seams were tested in dry condition and after 3 washing cycles at 60 C / 140 F with a total load of 2 kg per washing machine and dried flat. Primary results are very promising. Depending on the type of adhesive in combination with the substrate, seam strengths comparable to stitched seams can be obtained. The overall results of the difference in seam strength of the glued seams before and after washing is less than 2 %. Application Substrate Table 1: summary of results per substrate category Synthetic polymer (polyolefine) based hotmelt Water-based anionic stabilized PU-dispersion Aqueous dispersion of PES (paste) Lingerie 60% PA + 30% PES + 10% Lycra Workwear 33% cotton + 67% PES 65% PES + 34% cotton + 1% negastat 50% viscose FR + 50% Kermel Rain clothing 100% PA with PU-coating 100% PES with PU-coating 100% PU coated PES-knit ( 100% PVC coated PES-knit (330 g/m² - 100% PVC coated PES-knit (700 g/m² - 88% PES micro + 12% PA micro (laminated) Parasols 100% polyacrylnitril 100% polyolefine Medical 99% PES micro + 1% negastat Tenting 100% PA with PU-coating Sunscreens 30-40% glassfibre % PVC Legend: test not carried out (laminating temperature is too high for this fabric); very bad; bad; reasonable; good; very good 1. Synthetic polymer based hotmelts are suitable to glue coated and non-coated substrates with a high percentage of polyester, PVC/glass fibre and polyacrylnitril, which can resist assembling temperatures up to 180 C / 355 F during 6 seconds. Table 2: extraction of seam strength results (in Newton) with hotmelt adhesives Application Substrate Seam strength Seam strength Difference stitched seam glued seam Work wear 33% cotton + 67% PES 263 N 205 N 78 % 65% PES + 34% cotton + 1% negastat 283 N 223 N 79 % Medical 99% PES micro + 1% negastat 196 N 203 N 104 % Rain clothing 100% PES with PU-coating 241 N 228 N 95 % 100% PES with PU-coating 155 N 167 N 108 % Materials + Technology 4

5 2. Water-based and anionic stabilized polyurethane dispersions can be used for a wider range of substrates, such as viscose, kermel, polyurethane, polyester and low temperature resistible PU- or PVC-coated knits and wovens. Assembling temperature is max 90 C / 190 F during 6 seconds. Table 3: extraction of seam strength results (in Newton) with water based and anionic stabilized polyurethane dispersions Application Substrate Seam strength Seam strength Difference stitched seam glued seam Rain clothing 100% PU coated PES-knit ( 193 N 203 N 105 % 100% PVC coated PES-knit (700 g/m² N 313 N 150 % Medical 99% PES micro + 1% negastat 196 N 184 N 94 % 3. Aqueous dispersion of polyester powder (paste) is applicable on polyacrylnitril and PVC/glass fibre, where the assembling temperature is maximum 140 C / 285 F during 6 seconds. The substrates that show good results with these adhesives, are being used for sunscreens and parasols. Therefore more tests are needed to evaluate heat resistance and UV-light resistance So far a suitable adhesive for 55% of the tested substrates was found. For polyamides we remain with very poor results. Considering both the small differences in seam quality between seems glued with a polyolefine hotmelt and a water-based PU-dispersion and the prices of hotmelt installations and water- based adhesive installations (the installation for applying a hotmelt is about 400% more expensive than a cold adhesive applicator), we have decided to continue our research with water-based PU dispersions. For the next tests the surfaces of the substrates were pre-treated with a plasma torch. This treatment enhances wettability, printability and adhesion properties of the textile material by activating the surface. A flame treatment is uniform and intens. The air between two electrodes is ionised by applying an elecrical power (lower voltage than corona) after which it is forced into the atmosphere with pressurised air. Figure 6: flame treatment The thickness of the substrate is no limiting factor but only a small surface can be treated (approx. 5 cm²). This is sufficient for this application. Primarily test results have shown that the adhesive can be applied more evenly and that the seam strength is significantly increased. Further testing is needed. Materials + Technology 5

6 Application Table 4: summary of results per substrate category with/without prior ionised gas treatment Water-based anionic stabilized Substrate PU-dispersion (without plasma) Water-based anionic stabilized PU-dispersion (with plasma) Lingerie 60% PA + 30% PES + 10% Lycra Workwear 33% cotton + 67% PES 65% PES + 34% cotton + 1% negastat 50% viscose FR + 50% Kermel Rain clothing 100% PA with PU-coating 100% PES with PU-coating 100% PU coated PES-knit ( 100% PVC coated PES-knit (330 g/m² - 100% PVC coated PES-knit (700 g/m² - 88% PES micro + 12% PA micro (laminated) Parasols 100% polyacrylnitril 100% polyolefine Medical 99% PES micro + 1% negastat Tenting 100% PA with PU-coating Sunscreens 30-40% glassfibre % PVC Umbrellas 100% cotton 100% PA Legend: test not carried out (laminating temperature is too high for this fabric); very bad; bad; reasonable; good; very good In the upcoming weeks a valve jet spray installation will be installed on the cutter head. Intensive tests will be executed to confirm water based dispersion are suited to be applied according to the industrial concept where spraying over a long term could lead to a blockage of the spray head due to precipitation of adhesive particles. If necessary, this could be prevented by adding a small amount of solvent. Another important part of the project is to analyse the possibilities to integrate databases of different support programmes such as CAD/CAM, Product Data Management, 3D-bodyscanning into an Enterprise Resource Program. This is to optimise the computerisation of product development, customer management, planning, logistics, production, Figure 7: ERP environnement Materials + Technology 6

7 follow-up and distribution. Materials + Technology 7