DE10352752B3 - Continuous production of liquid crystal polymer film, as conductor paths or a barrier film, involves supplying powder to a heated calender roller and passing the melted mass between polishing and structured rollers - Google Patents

Abstract

For the continuous production of an isotropic liquid crystal polymer (LCP) film (F), a powder with a LCP content is passed continuously through a multi-stage heated roller assembly. The powder is applied from a hopper (P) to a calender roller (K), to be melted and cross linked by heat, with shearing of the powder through the calender roller. The material passes through polishing and structured rollers (W) to give the final film material.

Description

The The present invention relates to a process for continuous Production of isotropic LCP films by powder calendering and a isotropic LCP film produced thereby.

at The manufacture of LCP films occur due to the molecular structure of liquid crystalline polymers (LCP) when manufactured by usual Processes such as Blown film extrusion or flat film extrusion very strong molecular orientations which leads to a very strong anisotropy of the properties of the Lead slides. This anisotropy is associated with very poor tensile strength of the films perpendicular to the orientation direction of the polymers. moreover are the thermal expansion coefficient for anisotropic films and the shrinkage of the foils lengthways and different across the orientation of the crystalline domains. These properties are disadvantageous with regard to the use of the films for e.g. flexible conductor tracks or also for barrier foils etc.

There usually, however, a need for the highest possible isotropy Film properties exist, the usual manufacturing processes are not suitable to from liquid crystalline Polymer films with desired To produce properties.

Although in the US 6364652 A Processes are described in which an attempt is made to increase the isotropy of the films by post-treatment of the films, but on the one hand it is difficult to carry out these processes and on the other hand these processes are only partially successful.

The DE 696 19 818 T2 discloses a method for producing porous composite films made of polytetrafluoroethylene and LCP by, for example, calendering.

Besides, was already described (WO 02/24791 A2) that it is possible to make an isotropic film LCP (liquid crystalline Polymers) by using powders that are characterized by connect thermoplastic melting and therefore none into one Domains oriented towards of liquid crystals train how this e.g. is the case with extrusion.

On However, the disadvantage of the described method is that the powder for producing the film can be metered electrostatically on a carrier got to. Moreover if the process is a batch process, that only allows a very low throughput. In addition, that the described method is only a one-sided structuring the slide allowed. For structuring the other side of the film is an ex post Processing of the film necessary.

task the present invention was therefore to provide a method represent the continuous production of films containing liquid crystalline Polymers (LCP), with isotropic properties allowed.

According to the invention now surprisingly found it possible is LCP-containing powder in a continuous rolling process to be processed into an isotropic LCP film. The application of the Powder on the rolling mill can be used as an alternative to electrostatic Dosing is also easy by sprinkling with the help of a dosing funnel or squeegees or inflation by means of a metering sieve. An electrostatic Dosing is not absolutely necessary.

to Shaping becomes a multi-stage rolling mill such as one Calender roll used.

by virtue of the continuous processing by the calender roll is here a much higher one Throughput possible as described in the prior art. You can also use both sides of the slides immediately when producing the isotropic film into the desired shape brought, either by the rolling mill itself, if this as with the calender roll is multi-stage, or by downstream Structure rollers.

The Powder (size approx. 1-100 μm) is used melted by contact with the rolling mill, which is heated. The powder particles are then in the nip due to the elevated temperature and the resulting pressure. The usage of a calender it to produce a continuous film application. In particular embodiments can also the film surface through downstream smoothing or structure rolls with a special surface smoothness or structure be provided. The surface structure allows for example, conductor tracks or flow fields on both sides the film surface to apply.

The films obtainable by the process described according to the invention are distinguished in that, due to the isotropic properties, the aforementioned unfavorable properties associated with the anisotropy are also not encountered. The films accordingly have an isotropic tear strength. Furthermore, the foils are, for example, for flexible conductor tracks or for barriers films can be used.

• a) Aufbringen von LCP-haltigem Pulver auf eine Kalanderwalze,
• b) Aufschmelzen oder Vernetzen des Pulvers durch Beheizung,
• c) Scherung des Pulvers durch die Kalanderwalze.

The present invention therefore relates to a process for producing isotropic LCP films, characterized in that an LCP-containing powder is continuously processed into an isotropic LCP film by a multi-stage heated rolling mill, the process comprising the following steps:

• a) applying LCP-containing powder to a calender roll,
• b) melting or crosslinking the powder by heating,
• c) Shear the powder through the calender roll.

The Both sides of the foils are either directly through the Calender rolls to a desired one Shaped way, or by the additional step d), the one preferred embodiment represents, the film then by smoothing and / or Structural rollers are pressed to give the film the desired structure or to give calmness.

Preferably an LCP-containing powder with a particle size of 1 up to 100 μm, used.

The LCP-containing powders are commercially available or can alternatively by grinding the polymer or by an NAD process (non-aqueous dispersion = non-aqueous Polymer dispersion) can be obtained.

The The isotropic films are generally produced at a Temperature from 200 to 380 ° C, preferably at 240 to 340 ° C.

Possibly the calender rolls by applying a voltage of 20 kV electrically charged to by the electrostatic charge achieved to bring about a more homogeneous distribution of the polymer particles in the nip.

It can all common in the relevant Rolling mills or calender rolls described in the specialist literature in a generally conventional manner Manner can be used (Friedrich Johannaber, plastics machine operator, Hanser Fachbuchverlag, edition November 2003; Friedrich Johannaber, Klaus Stoeckhert, plastic machine operator, 2. Ed., 1984).

Under According to the invention, isotropic films are preferably understood to be films which have a difference in the coefficient of thermal expansion (Test method ASTM D-696) in two directions in the x / y plane, the perpendicular to each other, less than 15 ppm (parts per million), particularly preferably less than 10 ppm, especially less than 5 ppm.

By a tensile test (IPC-TM 650, method 2.4.19) with the according to the inventive method obtained film sections along and transverse to the direction of tension at a constant rate of expansion can be shown that the tensile strength in the x and y direction is approximately the same and thus the anisotropy is significantly reduced.

The film thickness is generally between 5 and 100 microns, preferably 10-50 microns, and can be regulated by the gap of the last pair of rollers. To this A specially corrected roller is used for this purpose smallest gap widths possible.

liquid crystalline Polymers are known to the person skilled in the art. This can be, for example trade lyotropic or thermotropic LCPs. The liquid crystalline polymers can be thermoplastic or be thermosetting. Suitable thermotropic polymers include, for example liquid crystalline Polyester, liquid crystalline Polycarbonates, liquid crystalline Polyetheretherketones, liquid crystalline Polyetherketone ketones and / or liquid crystalline Polyesterimides. Special embodiments on liquid crystalline Polymers include aromatic polyesters, polyester amides, polyamide imides, Polyester carbonates and / or polyazomethines.

Further more detailed examples of Suitable LCP-containing polymers can be found in WO 02/24791 A2 to the expressly Reference is made.

It can also mixtures of liquid crystalline ones Polymers with each other or with other non-liquid crystalline ones Polymers are used.

The LCP-containing polymers can also usual Additives such as inorganic and organic fillers and stabilizers in common practice Contain quantities (WO 02/24791 A2).

The by the method according to the invention LCP-containing films produced can be used, for example, as flexible carrier of conductor tracks or as barrier films.

1 explains the process by way of example.

1 shows a process variant in which, in addition to the calender (K) shown in simplified form, downstream smoothing and structure rolls (W) are used.

With the help of the powder funnel (P) the LCP powder (L) is heated evenly into the gap of the heated ten calender (K) filled. The plasticized, pressed and preformed material is rolled out by the smoothing and structure rollers (W) to a film (F) with the desired surface quality.

Claims (7)

A process for producing isotropic LCP films, characterized in that an LCP-containing powder is continuously processed into an isotropic LCP film by a multi-stage heated rolling mill, comprising the steps: a) applying LCP-containing powder to a calender roll, b ) Melting or crosslinking the powder by heating, c) shearing the powder by the calender roll. A method according to claim 1, characterized in that the process as an additional Step the pressing by smoothing and structured rollers. A method according to claim 1 or 2, characterized in that that the LCP-containing Powder a particle size of 1 up to 100 μm has. Procedure according to a of claims 1 - 3, thereby characterized that the production takes place at a temperature of 200 - 380 ° C. LCP-containing film, obtainable by a process according to one or more of claims 1-4. Use of liquid crystalline Polymers for the production of isotropic films in a continuous Method according to claim 1. Use of a film according to claim 5 as more flexible carrier of conductor tracks or as a barrier film.