POLYMER COMPOSITIONS AND PRODUCTS FORMED THEREWITH
The present disclosure provides compositions and products formed therefrom. In particular, the disclosure provides elastomeric latex articles, such as gloves and condoms, that can be prepared utilizing a styrene-polyisoprene-styrene (SIS) latex. The elastomeric articles can exhibit desired tensile properties while being substantially or completely free of undesired components, such as sulfur and zinc oxide, which can be allergens. The disclosure further provides methods of preparing elastomeric latex articles.
1 . An elastomeric article comprising:
at least one layer of a composition of a polymer latex,
where the polymer latex is a polystyrene-polyisoprene-polystyrene (SIS) polymer latex,
where the elastomeric article is configured as a condom, and
where the elastomeric article has a tensile strength of about 25 MPa or greater when measured in accordance with ASTM D412 and has a tensile modulus at 500% elongation of less than 2.5 MPa when measured in accordance with ASTM D412.
2 . The elastomeric article of claim 1 , where the elastomeric article exhibits a tear strength of at least 2 N/mm when measured in accordance with ASTM D624-00.
3 . The elastomeric article of claim 1 , where the elastomeric article exhibits an elongation at break of about 1100% or greater.
4 . The elastomeric article of claim 1 , where the elastomeric article exhibits a Young's modulus (E′) that is less than 1 MPa at a frequency of 1 Hz and that is greater than 1 MPa at a frequency of 21.5 Hz.
5 . The elastomeric article of claim 1 , where the composition includes at least one sulfur donor, at least one cure accelerator, and an amphoteric surfactant.
6 . The elastomeric article of claim 1 , where the at least one layer has a substantially uniform thickness across the at least one layer.
7 . The elastomeric article of claim 1 , where the SIS polymer latex is the only polymer latex in the composition.
8 . An elastomeric article comprising:
at least one layer of a composition of a polymer latex,
where the polymer latex is a polystyrene-polyisoprene-polystyrene (SIS) polymer latex,
where the elastomeric article is configured as a condom, and
where the composition is prevulcanized and cured so that the elastomeric article has a tensile strength of about 25 MPa or greater when measured in accordance with ASTM D412 and has a tensile modulus at 500% elongation of less than 2.5 MPa when measured in accordance with ASTM D412.
9 . The elastomeric article of claim 8 , where the elastomeric article exhibits a tear strength of at least 2 N/mm when measured in accordance with ASTM D624-00 and exhibits an elongation at break of about 1100% or greater.
10 . The elastomeric article of claim 8 , where the elastomeric article exhibits a Young's modulus (E′) that is less than 1 MPa at a frequency of 1 Hz and that is greater than 1 MPa at a frequency of 21.5 Hz.
11 . The elastomeric article of claim 8 , where the composition includes at least one sulfur donor, at least one cure accelerator, and an amphoteric surfactant.
12 . The elastomeric article of claim 8 , where the at least one layer has a substantially uniform thickness across the at least one layer.
13 . The elastomeric article of claim 8 , where the SIS polymer latex is the only polymer latex in the composition.
14 . An elastomeric article comprising:
a polystyrene-polyisoprene-polystyrene (SIS) polymer latex composition,
where the elastomeric article has a tensile strength of about 25 MPa or greater when measured in accordance with ASTM D412 and has a tensile modulus at 500% elongation of less than 2.5 MPa when measured in accordance with ASTM D412, and
where the elastomeric article is prepared according to a method comprising:
compounding the SIS polymer latex composition with at least one sulfur donor, at least one cure accelerator, and at least one amphoteric surfactant to form a compounded SIS polymer latex composition;
prevulcanizing the compounded SIS polymer latex composition under conditions effective to form a prevulcanized SIS polymer latex composition that has a relaxed modulus of about 0.50 MPa to about 0.61 MPa;
dipping a former into the prevulcanized SIS polymer latex composition to form at least one layer of the prevulcanized SIS polymer latex composition thereon; and
curing the at least one layer of the prevulcanized SIS polymer latex composition on the former to provide the elastomeric article.
15 . The elastomeric article of claim 14 , where the method of preparing the elastomeric article comprises prevulcanizing the compounded SIS polymer latex composition at a first temperature for a first time period and then at a second, lower temperature for a second time period.
16 . The elastomeric article of claim 15 , where the first temperature is in a range of about 32° C. to about 38° C., and the first time period is in a range of about 0.5 hours to about 18 hours.
17 . The elastomeric article of claim 15 , where the second temperature is in a range of about 26° C. to about 32° C., and the second time period is in a range of about 2 hours to about 36 hours.
18 . The elastomeric article of claim 15 , where the first temperature and the second temperature are separated by at least 4° C.
19 . The elastomeric article of claim 14 , where the relaxed modulus is measurable according to a test comprising:
preparing a tube-shaped film of the prevulcanized SIS polymer latex composition on a dipping structure;
rolling the tube shaped film to form a ring;
stretching the ring using a tensile tester to about 100% extension for about 1 minute to identify a load; and
calculating the relaxed modulus using the formula:
Relaxed
Modulus
(
MPa
)
=
(
F
×
d
×
C
)
/
2
M
wherein F is the load in Newtons, dis a density of the latex ring in grams per cubic centimeter, C is an external circumference of the dipping structure in centimeters, and M is the mass of the latex ring in grams.
20 . The elastomeric article of claim 14 , where the SIS polymer latex is the only polymer latex in the SIS polymer latex composition.
21 . The elastomeric article of claim 14 , where the elastomeric article is configured as a condom.
22 . The elastomeric article of claim 14 , where the elastomeric article exhibits a tear strength of at least 2 N/mm when measured in accordance with ASTM D624-00 and exhibits an elongation at break of about 1100% or greater.
23 . The elastomeric article of claim 14 , where the at least one layer of the prevulcanized SIS polymer latex composition has a substantially uniform thickness across the at least one layer.
24 . An elastomeric article prepared according to a method comprising:
preparing a compounded polystyrene-polyisoprene-polystyrene (SIS) polymer latex composition;
prevulcanizing the compounded SIS polymer latex composition under conditions effective to form a prevulcanized SIS polymer latex composition that has a relaxed modulus of about 0.50 MPa to about 0.61 MPa;
dipping a former into the prevulcanized SIS polymer latex composition to form at least one layer of the prevulcanized SIS polymer latex composition thereon; and
curing the at least one layer of the prevulcanized SIS polymer latex composition on the former to provide the elastomeric article;
where the elastomeric article is configured as a condom; and
where the elastomeric article has a tensile strength of about 25 MPa or greater when measured in accordance with ASTM D412 and has a tensile modulus at 500% elongation of less than 2.5 MPa when measured in accordance with ASTM D412.
25 . The elastomeric article of claim 24 , where the at least one layer of the prevulcanized SIS polymer latex composition has a substantially uniform thickness across the at least one layer.
26 . The elastomeric article of claim 24 , where the method of preparing the elastomeric article comprises prevulcanizing the compounded SIS polymer latex composition at a first temperature for a first time period and then at a second, lower temperature for a second time period.
27 . The elastomeric article of claim 26 , where the first temperature is in a range of about 32° C. to about 38° C., and the first time period is in a range of about 0.5 hours to about 18 hours.
28 . The elastomeric article of claim 26 , where the second temperature is in a range of about 26° C. to about 32° C., and the second time period is in a range of about 2 hours to about 36 hours.
29 . The elastomeric article of claim 26 , where the first temperature and the second temperature are separated by at least 4° C.
30 . The elastomeric article of claim 26 , where the relaxed modulus is measurable according to a test comprising:
preparing a tube-shaped film of the prevulcanized SIS polymer latex composition on a dipping structure;
rolling the tube shaped film to form a ring;
stretching the ring using a tensile tester to about 100% extension for about 1 minute to identify a load; and
calculating the relaxed modulus using the formula:
Relaxed
Modulus
(
MPa
)
=
(
F
×
d
×
C
)
/
2
M
wherein F is the load in Newtons, dis a density of the latex ring in grams per cubic centimeter, C is an external circumference of the dipping structure in centimeters, and M is the mass of the latex ring in grams.