Clear film for tapes and labels

Patent metadata

Field	Value
Publication number	US-11718077-B2
Application number	US-202217576413-A
Country	US
Kind code	B2
Filing date	Jan 14, 2022
Priority date	Feb 27, 2018
Publication date	Aug 8, 2023
Grant date	Aug 8, 2023

Abstract

A multilayer film for use in adhesive tape or adhesive label applications comprising a core layer and skin layers on each side of the core layer. The core layer comprises a polypropylene mini-random homopolymer, wherein the mini-random homopolymer comprises polypropylene, up to 2 wt % ethylene components, and a acid neutralizer in a concentration up to 5000 ppm calcium. The skin layers each comprise a) at least about 95 wt % of a polypropylene mini-random homopolymer comprising polypropylene, up to 2 wt % ethylene components, and an acid neutralizer in a concentration up to about 5000 ppm, and b) an anti-block agent in a concentration up to about 1 wt %, wherein the anti-block agent comprises at least 95 wt % homopolymer of polypropylene and 1 to 5 wt % of silica having a particle size between about 1 to 3 μm.

First claim

What is claimed is:

1. A multilayer film for use in adhesive tape or adhesive label applications comprising:
a core layer comprising a polypropylene mini-random homopolymer, wherein the mini-random homopolymer comprises polypropylene, up to 2 wt % ethylene components, and an acid neutralizer in a concentration up to 5000 ppm calcium;
a first skin layer on a first side of the core layer and a second skin layer on a second side of the core layer, wherein the skin layers each comprise
a) at least about 95 wt % of a polypropylene mini-random homopolymer comprising polypropylene, up to 2 wt % ethylene components, an acid neutralizer in a concentration up to about 5000 ppm, and
b) an anti-block agent comprising homopolymer of polypropylene and silica having a particle size between about 1 to 3 μm;

wherein the first and second skin layers each have an amount of the homopolymer of polypropylene by weight and an amount of the silica by weight and wherein a ratio of the amount of the homopolymer of polypropylene by weight to the amount of silica by weight is greater than 95-to-5;
wherein the first and second skin layers comprise from 20 ppm to 450 ppm silica by weight.

2. The multilayer film of claim 1 consisting of the core layer and the first and second skin layers.

3. The multilayer film of claim 1 wherein the anti-block agent is present in a concentration of up to about 1 wt %.

4. The multilayer film of claim 1 , wherein the first and second layers comprise from 100 ppm to 500 ppm silica by weight.

5. The multilayer film of claim 1 wherein the core layer has a thickness between about 20 and about 200 μm.

6. The multilayer film of claim 1 wherein the core layer has a thickness between about 25 and about 75 μm.

7. The multilayer film of claim 1 wherein each skin layer has a thickness between about 0.25 and about 1.5 μm.

8. The multilayer film of claim 1 wherein:
the multilayer film consists of the core layer and the first and second skin layers;
the core layer has a thickness between about 20 and about 200 μm; and
each skin layer has a thickness between about 0.25 and about 1.5 μm.

9. The multilayer film of claim 1 wherein:
the multilayer film consists of the core layer and the first and second skin layers;
the core layer has a thickness between about 25 and about 75 μm; and
each skin layer has a thickness between about 0.25 and about 1.5 μm.

10. The multilayer film of claim 1 wherein the core layer comprises at least about 97 wt % of said polypropylene mini-random homopolymer.

11. The multilayer film of claim 1 wherein the core layer consists of only said polypropylene mini-random homopolymer.

12. The multilayer film of claim 3 wherein each skin layer comprises 95 to 99.8 wt % of the polypropylene mini-random homopolymer and 0.2 to 1 wt % of the anti-block agent.

13. The multilayer film of claim 3 wherein each skin layer consists of 0.2 to 1 wt % of the anti-block agent and a balance of the polypropylene mini-random homopolymer.

14. The multilayer film of claim 1 wherein the acid neutralizer is calcium stearate.

15. The multilayer film of claim 1 wherein the polypropylene mini-random homopolymer of the skin layer comprises between 300 and 4600 ppm of calcium stearate as the acid neutralizer.

16. The multilayer film of claim 1 wherein the mini-random homopolymer in at least one of the core layer and the skin layer comprises between 325 and 750 ppm of calcium stearate as the acid neutralizer.

17. The multilayer film of claim 1 wherein:
the multilayer film consists of the core layer and the first and second skin layers;
the core layer has a thickness between about 20 and about 200 μm;
each skin layer has a thickness between about 0.25 and about 1.5 μm;
the core layer comprises at least about 97 wt % of said polypropylene mini-random homopolymer;
each skin layer comprises 95 to 99.8 wt % of the polypropylene mini-random homopolymer and 0.2 to 1 wt % of the anti-block agent;
the skin layer polypropylene mini-random polymer comprises between 325 and 750 ppm calcium stearate as the acid neutralizer; and
the anti-block agent comprises at least 95 wt % homopolymer of polypropylene and 1 to 5 wt % of 1 to 3 micron particle size silica.

18. The multilayer film of claim 1 wherein the multilayer film has a haze value of less than 2%.

19. An adhesive tape or an adhesive label comprising the multilayer film of claim 1 and an adhesive on one of the skin layers.

20. The adhesive tape or the adhesive label of claim 19 wherein the adhesive is a hot melt adhesive.

Assignees

• Inteplast Group Corp
• Interplast Group Corp

Inventors

• Wong Jame
• Watts Chris
• Hwang Jenchyou
• Rosales Juan
• O'Reilly Todd
• Silen Ron
• Vasquez Lisa

Classifications

• B32B27/20 Primary

  using fillers, pigments, thixotroping agents · CPC title

• B32B27/08

  of synthetic resin · CPC title

• B32B27/32 Primary

  comprising polyolefins {(comprising vinyl (co)polymers or acrylic (co)polymers B32B27/30)} · CPC title

• B32B2250/03

  3 layers · CPC title

• B32B2250/40

  Symmetrical or sandwich layers, e.g. ABA, ABCBA, ABCCBA · CPC title