Stock material or miscellaneous articles – Web or sheet containing structurally defined element or... – Including a second component containing structurally defined...
Patent
1995-04-05
1997-12-16
Yamnitzky, Marie R.
Stock material or miscellaneous articles
Web or sheet containing structurally defined element or...
Including a second component containing structurally defined...
428328, 428331, 428403, 428405, 428480, 428220, 523212, 523213, B32B 502, C08K 906
Patent
active
056983093
DESCRIPTION:
BRIEF SUMMARY
The invention relates to moldings, in particular films, which contain at least one polyester layer and which contain surface-modified oxide particles. The films are preferably single-layer or multilayer monoaxially or biaxially oriented and heat-set films in which at least one layer is predominantly composed of a polyester. This polyester layer contains oxide particles which are modified at their surface so that they are covalently bonded in the polyester matrix.
Owing to their superior properties, such as their tensile strength, their ultimate tensile strength, their modulus of elasticity, their transparency, their chemical and thermal stability and the like, biaxially oriented films of polyester, in particular of polyethylene terephthalate, polyethylene naphthalate or polycyclohexane-dimethanol terephthalate, are used in large amounts in many industrial areas, such as, for example, in the reprographic sector, as a dielectric for capacitors, as substrate films for magnetic recording media, such as, for example, for audio, video and computer tapes and floppy disks, as ribbons for thermal transfer printing, as blocking foils and release films and as packaging material.
For the various fields of use, the polyester films must meet specific requirements, which are usually achieved with the aid of the raw material formulations and/or by means of specific process engineering during their production.
The surface structure of the films is particularly important here because it is critical for the frictional and abrasion behavior during the production and processing of the films.
Films having an extremely smooth surface exhibit poor frictional behavior which has an adverse effect both during their production and during their further processing.
Overcoming or reducing the stated disadvantages by incorporating inorganic and/or organic inert particles having a defined particle size distribution forms part of the prior art. Examples of such inert particles, which may be used alone or in combination, are CaCO.sub.3, TiO.sub.2, Al.sub.2 O.sub.3, ZrO.sub.2, BASO.sub.4, calcium phosphate, kaolin, SiO.sub.2 or natural and synthetic silicates.
Owing to their inadequate binding in the polymer matrix, the incorporation of the inert particles is associated with other disadvantages, some of which are serious. In the case of magnetic tapes, the inadequately bound inert particles may be torn out of the surface of the substrate film, for example during repeated use, and may thus adversely affect the electromagnetic properties of the tape to such an extent that complete loss of information may result. In the case of capacitor films, on the other hand, impairment of the dielectric properties may lead to electrical breakdown.
To improve the affinity of the inert particles for the polymer matrix and hence to improve the quality, i.e. the property profile of the moldings produced with the use of these inert particles, it was proposed to subject them to a surface treatment, depending on their chemical composition.
The possibilities of surface modification of carbonate fillers with the aim of influencing the interactions at, in particular, the CaCO.sub.3 /polymer and Rubber!, 37th year, Issue 8/1990, page 269 et seq.
U.S. Pat. No. 3,227,675 describes the treatment of "clays" (kaolins) with organosilicon compounds in order to achieve better binding in a polymer matrix.
DE-A-35 34 143 describes monodisperse SiO.sub.2 particles which are preferably intended for chromatographic purposes and whose functional groups present at the surface have been reacted with organotrialkoxysilanes.
A process for modifying synthetic silicate fillers with sulfur-containing organosilicon compounds to improve their binding in vulcanizable rubber blends is described in EP-A-0 177 674.
U.S. Pat. No. 4,567,030 likewise describes monodisperse mixed oxide particles which may be used as "fillers" and whose surfaces are modified with a .gamma.-aminopropyltrimethoxysilane or silanes which contain ethylenically unsaturated groups in order to improve the moisture resistan
REFERENCES:
patent: 4176124 (1979-11-01), Darms et al.
patent: 4328041 (1982-05-01), Wilson
patent: 5162155 (1992-11-01), Berndt et al.
patent: 5494949 (1996-02-01), Kinkel et al.
Dallmann Hermann
Kinkel Joachim
Marquard Kurt
Pohl Ludwig
Hoechst Aktiengesellschaft
Yamnitzky Marie R.
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