# US 11,441,013 B2 · Method to adjust the elongation required to effect a color change in polymeric stretch films incorporating mechanochromic dyes

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- Number: US 11,441,013 B2
- Document ID: US11441013B2
- Status: Granted
- Kind: B2
- Application number: 16/967,464
- Filed: 2019-03-13
- Published: 2021-07-22
- Granted: 2022-09-13
- Earliest claimed: 2018-03-29
- Assignees: Dow Global Technologies LLC
- Applicants: Dow Global Technologies LLC
- Inventors: Justice Alaboson
- Web page: https://patentgrep.com/patent/US11441013B2

## CPC

- C08K 5/353: Five-membered rings
- B29B 7/88: Adding charges {, i.e. additives}
- B29C 48/022: {characterised by the choice of material}
- B29C 48/10: flexible, e.g. blown foils
- B29C 48/21: the layers being joined at their surfaces
- B32B 7/08: by mechanical means
- B32B 27/08: of synthetic resin
- B32B 27/18: characterised by the use of special additives
- B32B 27/20: using fillers, pigments, thixotroping agents
- B32B 27/32: comprising polyolefins {(comprising vinyl (co)polymers or acrylic (co)polymers B32B27/30)}
- B29K 2105/0032: {Pigments, colouring agents or opacifiyng agents}
- B29L 2031/712: {Containers; Packaging elements or accessories, Packages (closures therefor B29L2031/56; ink or toner cartridges B29L2031/7678; squeeze tubes B29L2023/20; suitcases B29L2031/7418)}
- B32B 2270/00: Resin or rubber layer containing a blend of at least two different polymers
- B32B 2307/4026: within the layer by addition of a colorant, e.g. pigments, dyes
- B32B 2307/51: Elastic
- B32B 2307/514: Oriented
- B32B 2553/00: Packaging equipment or accessories not otherwise provided for
- C08K: Use of inorganic or non-macromolecular organic substances as compounding ingredients (paints, inks, varnishes, dyes, polishes, adhesives C09)
- B29B: PREPARATION OR PRETREATMENT OF THE MATERIAL TO BE SHAPED; MAKING GRANULES OR PREFORMS; RECOVERY OF PLASTICS OR OTHER CONSTITUENTS OF WASTE MATERIAL CONTAINING PLASTICS
- B29C: SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING (making preforms B29B11/00; making laminated products by combining previously unconnected layers which become one product whose layers will remain together B32B37/00 - B32B41/00)
- B32B: LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
- B29K: INDEXING SCHEME ASSOCIATED WITH SUBCLASSES B29B, B29C OR B29D, RELATING TO MOULDING MATERIALS OR TO MATERIALS FOR {MOULDS, } REINFORCEMENTS, FILLERS OR PREFORMED PARTS, e.g. INSERTS
- B29L: INDEXING SCHEME ASSOCIATED WITH SUBCLASS B29C, RELATING TO PARTICULAR ARTICLES

## Abstract

The present disclosure relates a method to adjust the amount of elongation required to effect a color change in a polymer stretch film. A first aspect of the invention is a method which method comprises selecting a polyolefin resin having a given density; admixing a given amount of the AIE mechanochromic dye into a melt of the polyolefin resin; making a film of a desired thickness from the polyolefin resin containing the mechanochromic dye; determining the level of elongation needed to effect a color change in the resulting film; and adjusting the density of the polyolefin resin to change the level of elongation needed to effect the color change to the desired level.

## Claims

### Claim 1

A method to adjust the amount of elongation required to effect a color change in a polymer stretch film comprising at least a first layer comprising a polyolefin resin and an AIE mechanochromic dye dispersed within the first layer, the method comprising the following steps:
a. selecting a polyolefin resin having a given density;
b. admixing a given amount of the AIE mechanochromic dye into a melt of the polyolefin resin;
c. making a film comprising at least a first layer which first layer comprises the polyolefin resin containing the mechanochromic dye;
d. determining the level of elongation needed to effect a color change in the resulting film;
e. adjusting the density of the polyolefin resin in the first layer to change the level of elongation needed to effect the color change to the desired level.

### Claim 2 (depends on 1)

The method of claim 1 wherein one or more factors selected from the group consisting of the density of the polyolefin resin, the identity of the AIE mechanochromic dye, the amount of the AIE mechanochromic dye, the thickness of the first layer and the elongation required to effect a color change are inputted in a database, and the database is used to predict the combination of factors required to produce a color change at a desired elongation level, and that that prediction is used to select the initial density of the polyolefin resin used in the first layer.

### Claim 3 (depends on 1)

The method of claim 1 wherein the polyolefin resin is a polyethylene.

### Claim 4 (depends on 1)

The method of claim 1 wherein the density of the polyolefin resin is adjusted by blending a second polyolefin resin having a density which is different than the first polyolefin resin in an amount to effect the desired change in overall density.

### Claim 5 (depends on 1)

The method of claim 1 wherein the AIE mechanochromic dye is selected from the group consisting of bis(benzoxazolyl)stilbene, perylene bisimide derivatives, and cyano substituted oligomers of (p-phenylene-vinylene)s.

### Claim 6 (depends on 1)

The method of claim 1 further comprising the step of admixing one or more additional dyes, which additional dyes may be AIE mechanochromic, non-AIE-mechanochromic, or non-mechanochromic.

### Claim 7 (depends on 1)

The method of claim 1 further comprising the step of adjusting the quantity of the AIE mechanochromic dye to change the level of elongation needed to effect the color change to the desired level.

### Claim 8 (depends on 1)

The method of claim 1 wherein the step of determining the level of elongation needed to effect a color change in the resulting film is facilitated with the use of a UV light source.

### Claim 9 (depends on 1)

The method of claim 1 wherein the stretch film is a multilayer film.

### Claim 10 (depends on 9)

The method of claim 9 wherein the stretch film has at least three layers and the first layer is a non-skin layer.

### Claim 11 (depends on 1)

The method of claim 1 wherein the AIE mechanochromic dye is admixed into the polyolefin melt of the first layer in an amount of from 0.0001 to 1 percent by weight of the polyolefin melt.

### Claim 12 (depends on 11)

The method of claim 11 wherein the AIE mechanochromic dye is admixed in an amount of from 0.01 to 0.1 percent by weight of the polyolefin melt of the first layer.

### Claim 13

A method to match the amount of elongation required to effect a color change in a polymer stretch film comprising at least a first layer comprising a polyolefin resin and an AIE mechanochromic dye dispersed within the first layer with a desired amount of elongation for an intended application for the stretch film, the method comprising the following steps:
a. determining the level of elongation needed to effect a color change in the resulting film based on the intended application for the film;
b. selecting a polyolefin resin for use in the first layer, said polyolefin resin having a given density based on expected level of elongation needed to effect a color change in the resulting film;
c. admixing a given amount of the AIE mechanochromic dye into a melt of the polyolefin resin;
d. making a film comprising at least a first layer which is made from the polyolefin resin containing the mechanochromic dye;
e. optionally, if color change does not occur at the desired level of elongation for the resulting film, adjusting the density of the polyolefin resin in the first layer to change the level of elongation needed to effect the color change to the desired level.