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US 4,701,369 AGranted
Opaque polymer film laminate having an absorbent surface
AssigneeMobil Oil Corporation
InventorGary L. Duncan
Life of this patent
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Abstract
An oriented, opaque polymer film laminate which comprises: (a) a non-absorbent thermoplastic polymer core layer having an upper major surface and a lower major surface; and, (b) a liquid-absorbent, opaque surface layer adherently applied to the upper major surface of the core layer and, optionally, to the lower major surface of the core layer, said surface layer comprising a thermoplastic matrix polymer containing numerous opaquing voids, said voids containing one or more void-initiating particles derived from a material which is phase distinct and incompatible with the matrix material.
Claims31
An oriented, opaque polymer film laminate which comprises:
- (a) a non-absorbent thermoplastic polymer core layer having an upper major surface and a lower major surface;
- and,
- (b) a liquid-absorbent, opaque surface layer adherently applied to the upper major surface of the core layer and, optionally, to the lower major surface of the core layer, said surface layer comprising a thermoplastic matrix polymer containing numerous opaquing voids, said voids containing one or more void-intiating particles derives from a material which is phase distinct from, and incompatible with, the matrix material, there being present in said surface layer filler particles having a particle size from about 1 to about 15 microns as measured along the greatest dimension, said particles increasing the absorbency of surface layer(s).
A process for producing an oriented, opaque polymer film laminate which comprises:
- (a) providing a non-absorbent thermoplastic core layer having an upper major surface and lower major surface;
- (b) providing a surface layer by:
- (i) mixing a thermoplastic matrix polymer material with a void-initiating material which is phase distinct from, and incompatible with, the matrix polymer material and which possesses a melting point or glass transition temperature which is higher than the melting point or glass transition temperature of the matrix polymer material,
- (ii) heating the mixture of matrix polymer material and void-initiating material to a temperature which is at or above the melting point of the matrix polymer material,
- (iii) distributing the void-initiating material throughout the molten matrix polymer material in the form of microparticles, and
- (iv) forming the microparticle-containing matrix polymer material into said surface layer;
- (c) adherently applying the surface layer to the upper major surface of the core layer and, optionally, to the lower major surface of the core layer, to provide a polymer film laminate;
- and,
- (d) biaxially orienting the polymer film laminate at a temperature which is signifiantly greater than the glass transition temperature of the thermoplastic polymer matrix material of the surface layer, to form numerous opaquing voids in the surface layer(s) thereof, at least a portion of said voids becoming open during orienting so as to impart liquid-absorbent capability to the surfae layer(s).
6 more elements
An oreinted, opaque polymer film laminate which comprises:
- (a) a non-absorbent thermoplastic polymer core layer having an upper major surface and a lower major surface;
- and,
- (b) a liquid-absorbent, opaque surface layer adherently applied to the upper major surface of the core layer, and optionally, to the lower major surface of the core layer, said surface layer comprising a thermoplastic matrix polymer containing numerous opaquing voids, said voids containing one or more void-initiating particles derived from a material which is phase distinct from, and incompatible with, the matrix material, there being present in said surface layer filler particles provided as rods, fibers or filaments which increase the absorbency of the surface layers.
A process for producing an oriented, opaque polymer film laminate which comprises:
- (a) providing a non-absorbent thermoplastic core layer having an upper major surface and lower major surface;
- (b) providing a surface layer by:
- (i) mixing a thermoplastic matrix polymer material with a void-initiating material which is phase distinct from, and incompatible with, the matrix polymer material and which possesses a melting point or glass transition temperature which is higher than the melting point or glass transition temperature of the matrix polymer material,
- (ii) heating the mixture of matrix polymer material and void-initiating material to a temperature which is at or above the melting point of the matrix polymer material,
- (iii) distributing the void-initiating material throughout the molten matrix polymer material in the form of microparticles, and
- (iv) forming the microparticle-containing matrix polymer material into said surface layer;
- said surface including a minor amount of filler particles provided as rods, fibers or filaments, to enhance the absorbency of said surface layer(s);
- (c) adherently applying the surface layer to the upper major surface of the core layer and, optionally, to the lower major surface of the core layer, to provide a polymer film laminate;
- and,
- (d) biaxially orienting the polymer film laminate under selected temperature conditions to avoid excessive incidence of void splitting and/or film fibrillation, to form numerous opaquing voids in the surface layer(s) thereof, at least a portion of said voids becoming open during orienting so as to impart liquid-absorbent capability to the surface layer(s).
7 more elements
Dependencies are inferred from the claim text.