# US 12,110,429 B2 · Hot melt processable adhesive with ionic crosslinkers

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- Number: US 12,110,429 B2
- Document ID: US12110429B2
- Status: Granted
- Kind: B2
- Application number: 17/919,719
- Filed: 2021-04-28
- Published: 2023-06-01
- Granted: 2024-10-08
- Earliest claimed: 2020-04-29
- Assignees: 3M Innovative Properties Company
- Applicants: 3M Innovative Properties Company
- Inventors: Huiwen Tai; John A. Nielsen; Anish Kurian
- Web page: https://patentgrep.com/patent/US12110429B2

## CPC

- B32B 7/12: using interposed adhesives or interposed materials with bonding properties
- C09J 7/35: Heat-activated
- B32B 7/06: permitting easy separation
- B32B 27/08: of synthetic resin
- B32B 27/304: {comprising vinyl halide (co)polymers, e.g. PVC, PVDC, PVF, PVDF}
- B32B 27/306: {comprising vinyl acetate or vinyl alcohol (co)polymers}
- B32B 27/308: {comprising acrylic (co)polymers}
- B32B 27/32: comprising polyolefins {(comprising vinyl (co)polymers or acrylic (co)polymers B32B27/30)}
- B32B 27/36: comprising polyesters
- C08F 265/06: Polymerisation of acrylate or methacrylate esters on to polymers thereof
- C09J 4/06: {Organic non-macromolecular compounds having at least one polymerisable carbon-to-carbon unsaturated bond} in combination with a macromolecular compound other than an unsaturated polymer of groups C09J159/00 - C09J187/00
- C09J 5/06: involving heating of the applied adhesive
- C09J 11/06: organic
- C09J 133/10: Homopolymers or copolymers of methacrylic acid esters
- C09J 151/003: {grafted on to macromolecular compounds obtained by reactions only involving unsaturated carbon-to-carbon bonds (C09J151/04, C09J151/06 take precedence)}
- B32B 2250/24: All layers being polymeric
- B32B 2270/00: Resin or rubber layer containing a blend of at least two different polymers
- B32B 2307/412: Transparent
- B32B 2307/7163: Biodegradable
- B32B 2405/00: Adhesive articles, e.g. adhesive tapes
- C08F 220/1808: {C8-(meth)acrylate, e.g. isooctyl (meth)acrylate or 2-ethylhexyl (meth)acrylate}
- C09J 2301/304: the adhesive being heat-activatable, i.e. not tacky at temperatures inferior to 30°C
- C09J 2301/312: parameters being the characterizing feature
- C09J 2301/408: additives as essential feature of the adhesive layer
- C09J 2301/414: presence of a copolymer
- C09J 2400/226: in the substrate
- C09J 2433/00: Presence of (meth)acrylic polymer
- B32B: LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
- 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

## Abstract

Hot melt processable composition mixtures include an acid-functional (meth)acrylate-based adhesive composition and a zinc di-(meth)acrylate salt. The adhesive composition has a hot melt processing temperature, and the zinc salt has a melting point that is higher than the hot melt processing temperature of the adhesive composition. The mixture is hot melt processable, and upon application to a substrate, the mixture forms an ionically crosslinked layer with thermally reversable ionic crosslinks.

## Claims

### Claim 1

A hot melt processable composition mixture comprising:
an acid-functional (meth)acrylate-based adhesive composition with a hot melt processing temperature; and
a zinc di-(meth)acrylate salt with a melting point wherein the melting point is higher than the hot melt processing temperature of the acid-functional (meth)acrylate-based adhesive composition, wherein the mixture is hot melt processable,
and upon application to a substrate the mixture forms an ionically crosslinked layer comprising thermally reversable ionic crosslinks.

### Claim 2 (depends on 1)

The hot melt processable composition mixture of claim 1, wherein the hot melt processable composition mixture further comprises particles of thermoplastic material.

### Claim 3 (depends on 1)

The hot melt processable composition mixture of claim 1, wherein the hot melt processable composition mixture further comprises at least one additive comprising tackifiers, fillers, or pigments.

### Claim 4 (depends on 1)

The hot melt processable composition mixture of claim 1, wherein the acid-functional (meth)acrylate based adhesive composition comprises a copolymer comprising:
at least one alkyl (meth)acrylate monomer; and
at least one acid-functional co-polymerizable monomer.

### Claim 5 (depends on 1)

The hot melt processable composition mixture of claim 1, wherein the hot melt processing temperature of the acid-functional (meth)acrylate-based adhesive composition is less than 200° C. and the melting point of the zinc di-(meth)acrylate salt is greater than 200° C.

### Claim 6 (depends on 1)

The hot melt processable composition mixture of claim 1, wherein the zinc di-(meth)acrylate salt comprises a salt of General Formula 1:
[Zn2+][−O—(CO)—CR1═CH2]2 Formula 1
wherein R1 is an H or a methyl group; —(CO)— is a carbonyl group C═O.

### Claim 7 (depends on 1)

The hot melt processable composition mixture of claim 1, wherein the hot melt processable composition mixture comprises 0.75-5.0% by weight of the total hot melt processable composition mixture of zinc di-(meth)acrylate salt.

### Claim 8 (depends on 1)

The hot melt processable composition mixture of claim 1, wherein the hot melt processable composition mixture after crosslinking has a tan δ value of 0.8 or less when measured by a rheometer at 100° C., wherein tan δ is the tangent of the phase angle and the ratio of G″/G′.

### Claim 9

A multi-layer article comprising:
a first polymeric layer with a first major surface and a second major surface;
a hot melt processed, ionically crosslinked adhesive layer with a first major surface and a second major surface wherein the first major surface of the adhesive layer is in contact with the second major surface of the first polymeric layer; and
a second polymeric layer with a first major surface and a second major surface,
wherein the first major surface of the second polymeric layer is in contact with the second major surface of the hot melt processed, ionically crosslinked adhesive layer,
wherein the hot melt processed, ionically crosslinked adhesive layer comprises a hot melt processed mixture comprising:
an acid-functional (meth)acrylate-based adhesive composition with a hot melt processing temperature; and
a zinc di-(meth)acrylate salt with a melting point wherein the melting point is higher than the hot melt processing temperature of the acid-functional (meth)acrylate-based adhesive composition.

### Claim 10 (depends on 9)

The multi-layer article of claim 9, wherein the first polymeric layer and the second polymeric layer comprise hot melt processable layers, and wherein the multi-layer article is prepared by co-extrusion.

### Claim 11 (depends on 9)

The multi-layer article of claim 9, wherein at least one of the second major surface of the first polymeric layer and the first major surface of the second polymeric layer is a release surface.

### Claim 12 (depends on 9)

The multi-layer article of claim 9, wherein the acid- functional (meth)acrylate based adhesive composition comprises a copolymer comprising:
at least one alkyl (meth)acrylate monomer; and
at least one acid-functional co-polymerizable monomer.

### Claim 13 (depends on 9)

The multi-layer article of claim 9, wherein the hot melt processed, ionically crosslinked adhesive layer has a tan δ value of 0.8 or less when measured by a rheometer at 100° C., wherein tan δ is the tangent of the phase angle and the ratio of G″/G′.

### Claim 14

A method of forming a multi-layer article comprising:
forming a hot melt processable adhesive mixture comprising:
an acid-functional (meth)acrylate-based adhesive composition with a hot melt processing temperature; and
a zinc di-(meth)acrylate salt with a melting point wherein the melting point is higher than the hot melt processing temperature of the acid-functional (meth)acrylate-based adhesive composition;
hot melt mixing the hot melt processable adhesive mixture to form a flowable composition;
disposing the flowable composition onto the surface of a first film substrate. wherein the first film substrate comprises a coextruded flowable polymeric composition;
disposing a second film substrate on the surface of the adhesive composition to form a multi-layer flowable composition, wherein the second film substrate comprises a second coextruded flowable polymeric composition; and
cooling the multi-layer flowable composition to room temperature to form a multi-layer article with an ionically crosslinked adhesive layer.

### Claim 15 (depends on 14)

The method of claim 14, further comprising melt-blowing the multi-layer flowable composition to form a multi-layer melt-blown composition prior to cooling.

### Claim 16 (depends on 14)

The method of claim 14, wherein the hot melt processing temperature of the acid-functional (meth)acrylate-based adhesive composition is less than 200° C. and the melting point of the zinc di-(meth)acrylate salt is greater than 200° ° C.

### Claim 17 (depends on 14)

The method of claim 14, wherein the zinc di-(meth)acrylate salt comprises a salt of General Formula 1:
[Zn2+][−O—(CO)—CR1═CH2]2 Formula 1
wherein R1 is an H or methyl group; —(CO)— is a carbonyl group C═O.

### Claim 18 (depends on 14)

The method of claim 14, wherein the hot melt processable adhesive mixture comprises 0.75-5.0% by weight of the total composition of zinc di-(meth)acrylate salt.

### Claim 19 (depends on 14)

The method of claim 14, wherein the hot melt processable composition mixture after crosslinking has a tan δ value of 0.8 or less when measured by a rheometer at 100° C., wherein tan δ is the tangent of the phase angle and the ratio of G″/G′.