# US 8,464,719 B2 · Dip-formed synthetic polyisoprene latex articles with improved intraparticle and interparticle crosslinks

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- Number: US 8,464,719 B2
- Document ID: US8464719B2
- Status: Granted
- Kind: B2
- Application number: 13/277,445
- Filed: 2011-10-20
- Published: 2012-02-09
- Granted: 2013-06-18
- Earliest claimed: 2008-05-01
- Assignees: Ansell Healthcare Products LLC
- Applicants: David M. Lucas; Sugath Amarasekera; Dave Narasimhan; Adeline Ai Lin Kung
- Inventors: David M. Lucas; Sugath Amarasekera; Dave Narasimhan; Adeline Ai Lin Kung
- Web page: https://patentgrep.com/patent/US8464719B2

## CPC

- C08F 136/08: Isoprene
- A41D 19/0055: {Plastic or rubber gloves}
- A41D 19/0082: {Details}
- A61B 42/10: Surgical gloves
- A61F 6/04: Condoms, sheaths or the like {, e.g. combined with devices protecting against contagion}
- B32B 27/32: comprising polyolefins {(comprising vinyl (co)polymers or acrylic (co)polymers B32B27/30)}
- C08L 9/00: Compositions of homopolymers or copolymers of conjugated diene hydrocarbons
- C08L 23/20: having four to nine carbon atoms
- A61F 2006/043: {with more than one barrier}
- B29L 2031/4864: {Gloves}
- Y10T 428/2982: Particulate matter [e.g., sphere, flake, etc.]
- Y10T 428/31924: Including polyene monomers
- C08F: MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
- A41D: OUTERWEAR; PROTECTIVE GARMENTS; ACCESSORIES
- A61B: DIAGNOSIS; SURGERY; IDENTIFICATION (usefulness limited to only animals A61D)
- A61F: FILTERS IMPLANTABLE INTO BLOOD VESSELS; PROSTHESES; DEVICES PROVIDING PATENCY TO, OR PREVENTING COLLAPSING OF, TUBULAR STRUCTURES OF THE BODY, e.g. STENTS; ORTHOPAEDIC, NURSING OR CONTRACEPTIVE DEVICES; FOMENTATION; TREATMENT OR PROTECTION OF EYES OR EARS; BANDAGES, DRESSINGS OR ABSORBENT PADS; FIRST-AID KITS (dental prosthetics A61C)
- B32B: LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
- C08L: COMPOSITIONS OF MACROMOLECULAR COMPOUNDS (compositions based on polymerisable monomers C08F, C08G; artificial filaments or fibres D01F; textile treating compositions D06)
- B29L: INDEXING SCHEME ASSOCIATED WITH SUBCLASS B29C, RELATING TO PARTICULAR ARTICLES
- Y10T: TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION

## Abstract

A synthetic polyisoprene latex emulsion has pre-vulcanization composition and post vulcanization composition. The pre-vulcanization composition comprises soluble sulfur with high S8 ring structure that is catalytically broken by a zinc dithiocarbamate. Surfactants present in the pre-vulcanization composition wets synthetic polyisoprene particles and permeates small sized sulfur and accelerator molecules into the interior of these particles thereby pre-vulcanizing the particles. The degree of pre-vulcanization is verified by isopropanol index test. The latex emulsion has post-vulcanization composition with accelerators that crosslink inter-particle region during post vulcanization cure cycle. The dipped synthetic polyisoprene article is substantially uniformly cured both in the inter-particle and intra-particle regions and reliably exhibits high cross link density, uniform distribution of double bonds in TEM and zinc segregation at the boundaries or original particles by electron microprobe analysis. The films exhibit high tensile strength, tensile modulus, tear strength, burst pressure and burst volume.

## Claims

### Claim 1

A synthetic polyisoprene elastomeric glove or condom comprising:
synthetic polyisoprene particles that are pre-vulcanized and cured;
said synthetic polyisoprene particles bonded to each other through intra-polyisoprene particle crosslinks and inter-polyisoprene particle crosslinks;
wherein the intra-polyisoprene particle crosslinks and the inter-polyisoprene particle crosslinks are substantially uniform in said synthetic polyisoprene elastomeric glove or condom, wherein such uniformity is measured by one or more of the following
(a) the glove or condom exhibits a substantially conchoidal fracture when fractured at liquid nitrogen temperature, or
(b) the glove or condom exhibits a fracture surface with an absence of scanning electron microscope-viewable intra-polyisoprene particle and inter-polyisoprene particle features when ruptured at room temperature.

### Claim 2 (depends on 1)

The glove or condom of claim 1, wherein the molecular weight is less than about 6800 g/mol between the crosslinks.

### Claim 3 (depends on 2)

A condom of claim 2, wherein the condom has an elongation at break of at least 945%.

### Claim 4 (depends on 2)

The glove or condom of claim 2, wherein the glove or condom exhibits a fracture surface with an absence of scanning electron microscope-viewable intra-polyisoprene particle and inter-polyisoprene particle features when ruptured at room temperature.

### Claim 5 (depends on 1)

A condom of claim 1, wherein the condom has a tensile strength of at least 30 MPa.

### Claim 6 (depends on 5)

The condom of claim 5, wherein the molecular weight is less than about 6800 g/mol between the crosslinks.

### Claim 7 (depends on 5)

The condom of claim 5, wherein the condom exhibits a fracture surface with an absence of scanning electron microscope-viewable intra-polyisoprene particle and inter-polyisoprene particle features when ruptured at room temperature.

### Claim 8 (depends on 1)

The glove or condom of claim 1, wherein said latex article exhibits a substantially conchoidal fracture when fractured at liquid nitrogen temperature.

### Claim 9 (depends on 8)

The glove or condom of claim 8, wherein the molecular weight is less than about 6800 g/mol between the crosslinks.

### Claim 10 (depends on 8)

The glove or condom of claim 8, wherein the glove or condom exhibits a fracture surface with an absence of scanning electron microscope-viewable intra-polyisoprene particle and inter-polyisoprene particle features when ruptured at room temperature.

### Claim 11 (depends on 1)

The glove or condom of claim 1, wherein the glove or condom exhibits a fracture surface with an absence of scanning electron microscope-viewable intra-polyisoprene particle and inter-polyisoprene particle features when ruptured at room temperature.

### Claim 12 (depends on 11)

A condom of claim 11, wherein the condom has an elongation at break of at least 945%.

### Claim 13 (depends on 12)

A condom of claim 12, wherein said latex article exhibits a substantially conchoidal fracture when fractured at liquid nitrogen temperature.

### Claim 14 (depends on 1)

The glove or condom of claim 1, wherein the glove or condom exhibits scanning electron microscopic-viewable zinc and sulfur x-ray maps on a fracture surface when fractured at liquid nitrogen temperature, or when ruptured at room temperature, or both, shows presence of sulfur within a polyisoprene particle that is decorated by zinc.

### Claim 15 (depends on 1)

The glove or condom of claim 1, wherein microprobe elemental analysis shows an accumulation of zinc surrounding said synthetic polyisoprene particles.

### Claim 16 (depends on 1)

The glove or condom of claim 1, wherein TEM of an osmium tetroxide treated article shows uniformity of isoprene double bonds.

### Claim 17 (depends on 1)

The glove or condom of claim 1, wherein the glove or condom exhibits uniform intra-polyisoprene particle crosslinks and inter-polyisoprene particle crosslinks when fractured is such that a fracture surface passes through both inter-particle regions and intra-particle regions nonpreferentially.

### Claim 18 (depends on 17)

A condom of claim 17, having an elongation at break of at least 945%.

### Claim 19 (depends on 18)

The condom of claim 18, having a tensile strength of at least 30 MPa.

### Claim 20 (depends on 1)

A condom of claim 1, having an elongation at break of at least 945%.