Stock material or miscellaneous articles – Composite – Of polyamidoester
Patent
1998-05-18
2000-04-04
Krynski, William
Stock material or miscellaneous articles
Composite
Of polyamidoester
428195, 156 60, 1563317, 4274121, 4274124, 427369, B32B 2700, B32B 2740
Patent
active
060459182
DESCRIPTION:
BRIEF SUMMARY
The invention relates to a method for attaching a bicomponent polyurethane surface to a polyvinyl chloride surface. This method applies to the domain of bonding two polymers, particularly bonding polyurethane (PU) to polyvinyl chloride (PVC), particularly for making smart cards with and/or without projecting contacts.
Current methods of bonding polyurethane (PU) to a polyvinyl chloride (PVC) surface require a preliminary surface treatment step. This step modifies the surface state of the PVC, i.e. it modifies surface tensions, in order to obtain a satisfactory bond between the two polymers.
Surface treatment of this type is effected either with a degreaser such as methyl ethyl ketone (MEK) or acetone for example, or by flame treatment, or by plasma treatment, or finally by corona treatment. All these various treatments create free radicals at the PVC surface. These free radicals, are reactive to species that are capable of radical polymerization, hence principally to compounds with double bonds. However they are not reactive to compounds polymerizable by polycondensation. Now, polyurethanes are obtained by polycondensation. As a result, when a PVC surface is bonded to a PU surface after pretreatment in order to create free radicals at the PVC surface, the bond is of poor quality and is hence difficult to reproduce.
Moreover, such surface treatments pose many safety, implementation, and cost problems. This is because the products used are often toxic, and implementation of this preliminary step is tedious and time-consuming. Also, this cumbersome step entails high manufacturing cost.
The present invention overcomes all these disadvantages because it offers a method for bonding a bicomponent polyurethane surface to a polyvinyl chloride surface consisting of placing a resin comprising the two components necessary for polyurethane formation on a PVC surface, followed by a pressing step without prior surface treatment. For this purpose, one characteristic of the method according to the invention consists of incorporating a plasticizer into the polyurethane as it forms, during pressing.
According to another characteristic of the invention, the plasticizer is chosen from plasticizers that are compatible both with polyvinyl chloride (PVC) and with polyurethane (PU).
According to another characteristic of the invention, the plasticizer is incorporated into the polyurethane as it forms in proportions between 2 and 12 wt. %, preferably between 3 and 8 wt. %.
The method according to the invention overcomes all the disadvantages involved in the preliminary surface treatment step. Hence, safety of the operators is ensured since it is no longer necessary to use a hazardous product. Moreover, the time and the cost of implementation are considerably reduced. Finally, the bond between the PVC and PU is of better quality than that obtained by prior techniques and offers good reproducibility. The method according to the invention thus facilitates industrial implementation of bonding PU to PVC.
Plasticizers are generally used to improve the flexibility of a polymer. However, they have thus far never been used in adhesive formulations to improve bonding between two polymers. This is because plasticizers of the phthalate type for example, whose alkyl groups generally have between 4 and 11 carbons, namely plasticizers of the dibutyl phthalate, dioctyl phthalate, or diisoundecanoic phthalate type, are used to modify the physical properties of the polyurethane, namely to modify its flexibility, physical appearance, and environmental stability. Plasticizers with two long-chain alkyl groups, namely with 7 to 11 carbons, are preferred because they migrate less in the PU and hence less volatile than the plasticizers with short-chain alkyl groups.
Other features and advantages will emerge from reading the description, provided as an illustrative and non-limiting example.
One embodiment of the method according to the present invention consists of incorporating a plasticizer into one of these polymers when the PVC and PU surfaces are pres
REFERENCES:
patent: 4373081 (1983-02-01), Nachtkamp et al.
patent: 4424834 (1984-01-01), Sumi et al.
patent: 4436784 (1984-03-01), Ehrhart
patent: 5356717 (1994-10-01), Choki et al.
Leriche Christian Gustave Alain
Turin Joel Alain Jerome
Gemplus S.C.A.
Krynski William
Plottel Roland
Shewareged B.
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