# US 2019/0169392 A1 · Thermoplastic foam with concomitant expansion and curing

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- Number: US 2019/0169392 A1
- Document ID: US20190169392A1
- Status: Published application
- Kind: A1
- Application number: 16/324,502
- Filed: 2017-09-25
- Published: 2019-06-06
- Earliest claimed: 2016-09-30
- Assignees: Sika Technology AG
- Applicants: Sika Technology AG
- Inventors: Dusko PARIPOVIC
- Web page: https://patentgrep.com/patent/US20190169392A1

## CPC

- C08J 9/102: {Azo-compounds}
- B29C 44/02: for articles of definite length, i.e. discrete articles
- B29C 44/3415: {Heating or cooling}
- B29C 65/70: by moulding (using a particular moulding technique, see the relevant technique {, e.g. by injection B29C45/14467})
- C08J 9/0023: {containing oxygen}
- C08J 9/0061: {characterized by the use of several polymeric components}
- C08J 9/02: using blowing gases generated by the reacting monomers or modifying agents during the preparation or modification of macromolecules
- C08K 5/23: Azo-compounds
- C08L 23/08: Copolymers of ethene (C08L23/16 takes precedence)
- C08L 23/0869: with unsaturated acids, e.g. [meth]acrylic acid; with unsaturated esters, e.g. [meth]acrylic acid esters
- C08L 33/00: Compositions of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and only one being terminated by only one carboxyl radical, or of salts, anhydrides, esters, amides, imides or nitriles thereof; Compositions of derivatives of such polymers
- B29K 2101/12: Thermoplastic materials
- B29L 2031/26: Sealing devices, e.g. packaging for pistons or pipe joints
- C08J 2201/026: Crosslinking before of after foaming
- C08J 2203/04: N2 releasing, ex azodicarbonamide or nitroso compound
- C08J 2207/00: Foams characterised by their intended use
- C08J 2323/08: Copolymers of ethene (C08J2323/16 takes precedence)
- C08J 2423/08: Copolymers of ethene (C08J2423/16 takes precedence)
- C08J 2433/14: of esters containing halogen, nitrogen, sulfur, or oxygen atoms in addition to the carboxy oxygen
- C08K 5/134: Phenols containing ester groups
- C08L 2203/14: used for foams
- C08L 2205/025: containing two or more polymers of the same hierarchy C08L, and differing only in parameters such as density, comonomer content, molecular weight, structure
- C08J: WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H (working, e.g. shaping, of plastics B29)
- 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)
- C08K: Use of inorganic or non-macromolecular organic substances as compounding ingredients (paints, inks, varnishes, dyes, polishes, adhesives C09)
- C08L: COMPOSITIONS OF MACROMOLECULAR COMPOUNDS (compositions based on polymerisable monomers C08F, C08G; artificial filaments or fibres D01F; textile treating compositions D06)
- 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

A thermally expandable composition, includes between 20 and 85 wt.-% of least one thermoplastic polymer P cross-linkable by radical reaction, between 2 and 15 wt.-% of at least one azo radical initiator I, optionally up to 25 wt.-% of at least one adhesion promoter AD, up to 10 wt.-% of at least one tackifier T, up to 2.5 wt.-% of at least one antioxidant AO, and up to 2.5 wt.-% of at least one polyacrylate AC, having a molecular weight of less than 2,500 g/mol, wherein all individual amounts are based on the total composition before expansion. The thermally expandable composition is free of commonly used blowing agents such as azodicarbonamide, but shows excellent properties in terms of expansion stability over a wide temperature range between 120° C. and 200° C. and is especially suitable for baffle and/or reinforcement elements, e.g. in automotive manufacturing.

## Claims

### Claim 1

A thermally expandable composition, comprising
a) between 20 and 85 wt.-% of least one thermoplastic polymer P, cross-linkable by radical reaction;
b) between 2 and 15 wt.-% of at least one azo radical initiator I;
c) between 0 and 25 wt.-% of at least one adhesion promoter AD;
d) between 0 and 10 wt.-% of at least one tackifier T;
e) between 0 and 2.5 wt.-% of at least one antioxidant AO;
f) between 0 and 2.5 wt.-% of at least one polyacrylate AC, having a molecular weight of less than 2,500 g/mol;
wherein all individual amounts are based on the total composition before expansion.

### Claim 2 (depends on 1)

The thermally expandable composition according to claim 1, wherein said composition is free of peroxides, bicarbonates, azodicarbonamide, or 4,4′-oxybis(benzenesulfonyl hydrazide).

### Claim 3 (depends on 1)

The thermally expandable composition according to claim 1, wherein said polymer P comprises ethylene vinyl acetate and/or ethylene butyl acrylate and said polymer P or mixtures thereof exhibit a melt flow index according to ASTM D1238 of between 10 and 100 g/10 min.

### Claim 4 (depends on 1)

The thermally expandable composition according to claim 1, wherein said azo radical initiator I is selected from the group consisting of azonitrile compounds, alkylazo compounds, and azoamide compounds having a 10 h half-life in toluene at between 55 and 120° C.

### Claim 5 (depends on 1)

The thermally expandable composition according to claim 1, wherein said adhesion promoter AD comprises a thermoplastic polymer having glycidyl methacrylate groups and exhibiting a melt flow index according to ASTM D1238 of between 3 and 10 g/10 min.

### Claim 6 (depends on 1)

The thermally expandable composition according to claim 1, wherein said tackifier T comprises a C5 hydrocarbon resin which is optionally aromatically modified.

### Claim 7 (depends on 1)

The thermally expandable composition according to claim 1, wherein said antioxidant AO comprises a sterically hindered phenol compound with a melting point of at least 110° C.

### Claim 8 (depends on 1)

The thermally expandable composition according to claim 1, wherein said polyacrylate AC has an acrylate functionality of at least 4.

### Claim 9 (depends on 1)

Thermally expandable composition according to claim 1, comprising
between 60 and 75 wt.-% of said thermoplastic polymer P;
between 2.5 and 10 wt.-% said azo radical initiator I;
between 10 and 20 wt.-% of said adhesion promoter AD;
between 5 and 8 wt.-% of said tackifier T;
between 0.5 and 1.5 wt.-% of said antioxidant AO;
between 0.5 and 1.5 wt.-% of said polyacrylate AC; selected such that the sum of all individual wt.-% values does not exceed 100 wt.-%.

### Claim 10 (depends on 1)

A baffle and/or reinforcement element for hollow structures, wherein said element comprises or essentially consists of a thermally expandable composition according to claim 1.

### Claim 11 (depends on 10)

The baffle and/or reinforcement element of claim 10, wherein that said element comprises a carrier on which the thermally expandable composition is deposited or attached, wherein said carrier is made of a thermoplastic material.

### Claim 12 (depends on 11)

A process for manufacturing a baffle and/or reinforcement element according to claim 11, wherein the thermally expandable composition is injection-moulded onto the carrier or co-extruded with the carrier.

### Claim 13 (depends on 1)

A process for foaming a thermally expandable composition according to claim 1, wherein said thermally expandable composition is subjected to a temperature of between 120 and 200° C. for between 10 and 60 min and/or to UV irradiation with a UV intensity on the composition surface of at least 2.5 mW/cm−2 for between 1 and 60 min.

### Claim 14 (depends on 10)

A method comprising applying the baffle and/or reinforcement element of claim 10 to seal, baffle, or reinforce a cavity or hollow structure of a land-, water-, or air-vehicle and/or a cavity of a building wherein the transmission of noise, vibrations, humidity, and/or heat is reduced, and/or the object surrounding said cavity is mechanically strengthened.

### Claim 15 (depends on 1)

A method for sealing, baffling and/or reinforcing a cavity or hollow structure, wherein an element comprising a thermally expandable composition according to claim 1 is introduced into said cavity or hollow structure and subsequently expanded by heat and/or UV treatment such that said cavity or hollow structure is at least partially filled by the expanded composition.