# US 2019/0376884 A1 · Method for selecting adhesive with excellent folding stability

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- Number: US 2019/0376884 A1
- Document ID: US20190376884A1
- Status: Published application
- Kind: A1
- Application number: 16/478,408
- Filed: 2018-08-23
- Published: 2019-12-12
- Earliest claimed: 2017-09-11
- Assignees: LG Chem, Ltd.
- Applicants: LG Chem, Ltd.
- Inventors: Hyunsup LEE; Hyon Gyu PARK; Yoonkyung KWON; Myunghan LEE; Hee SONG
- Web page: https://patentgrep.com/patent/US20190376884A1

## CPC

- C09J 133/08: Homopolymers or copolymers of acrylic acid esters
- C08F 220/1804: {C4-(meth)acrylate, e.g. butyl (meth)acrylate, isobutyl (meth)acrylate or tert-butyl (meth)acrylate}
- C08F 220/1808: {C8-(meth)acrylate, e.g. isooctyl (meth)acrylate or 2-ethylhexyl (meth)acrylate}
- C09J 201/00: Adhesives based on unspecified macromolecular compounds
- G01N 3/00: Investigating strength properties of solid materials by application of mechanical stress
- G01N 3/08: by applying steady tensile or compressive forces (G01N3/28 takes precedence)
- G01N 3/20: by applying steady bending forces (G01N3/26, G01N3/28 take precedence)
- G01N 11/00: Investigating flow properties of materials, e.g. viscosity, plasticity; Analysing materials by determining flow properties
- G06F 7/544: for evaluating functions by calculation {(G06F7/4824 takes precedence)}
- G06F 17/10: Complex mathematical operations {(function generation by table look-up G06F1/03; evaluation of elementary functions by calculation G06F7/544)}
- H10K 77/111: {Flexible substrates}
- C09J 2301/312: parameters being the characterizing feature
- G09F 9/301: {flexible foldable or roll-able electronic displays, e.g. thin LCD, OLED}
- H10K 2102/311: {Flexible OLED}
- Y02E 10/549: Organic PV cells
- C09J: ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES (preparation of glue or gelatine C09H)
- C08F: MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
- G01N: INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES (measuring or testing apparatus or processes other than immunoassay, involving enzymes or microorganisms C12M, C12Q)
- G06F: ELECTRIC DIGITAL DATA PROCESSING (computer systems based on specific computational models G06N)
- H10K: ORGANIC ELECTRIC SOLID-STATE DEVICES
- G09F: DISPLAYING; ADVERTISING; SIGNS; LABELS OR NAME-PLATES; SEALS
- Y02E: REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION

## Abstract

The present invention relates to a method of deriving significant factors of rheological properties, which influence folding stability for developing an adhesive with excellent folding stability, and predicting folding stability through the same. It is possible to select an adhesive with excellent folding stability by measuring initial stress and a strain recovery rate as the significant factors, and measuring predicted folding stability (predicted number of times of folding) therefrom.

## Claims

### Claim 1

A method for selecting an adhesive having excellent folding stability, which comprises measuring an initial stress and a strain recovery of the adhesive by using a dynamic mechanical analyzer (DMA), and then calculating a predictive folding stability value of the adhesive by using Equation 1 below:
Predictive folding stability=1.587×1019(Strain recovery−4.722)(Initial stress−1.304). [Equation 1]

### Claim 2 (depends on 1)

The method for selecting an adhesive having excellent folding stability according to claim 1, wherein the predictive folding stability value is 40000 or more.

### Claim 3 (depends on 1)

The method for selecting an adhesive having excellent folding stability according to claim 1, wherein the initial stress and the strain recovery are values that cause the predictive folding stability value to be 40000 or more.

### Claim 4 (depends on 1)

The method for selecting an adhesive having excellent folding stability according to claim 1, wherein the initial stress is 7000 to 25000 Pa, and the strain recovery is 70% to 99%.

### Claim 5 (depends on 4)

The method for selecting an adhesive having excellent folding stability according to claim 4, wherein the initial stress is 12000 to 15000 Pa, and the strain recovery is 80% to 87%.

### Claim 6 (depends on 1)

The method for selecting an adhesive having excellent folding stability according to claim 1, wherein Pearson's correlation coefficient between the folding stability and the combined factors of the initial stress and the strain recovery is 0.95.

### Claim 7

A foldable display comprising an adhesive, wherein the adhesive has a predictive folding stability value that is greater than or equal to 40000, wherein the predictive folding stability value is calculated based on measuring an initial stress and a strain recovery of the adhesive by using a dynamic mechanical analyzer (DMA), and then calculating the predictive folding stability value (predictive folding number) of the adhesive by using Equation 1 below:
Predictive folding stability=1.587×1019(Strain recovery−4.722)(Initial stress−1.304). [Equation 1]