Scratch and scuff resistant polymer

The present invention relates to a scratch resistant polymer composition having a polymer that includes a copolyetherester elastomer, said polymer having a hardness of from 25D to 82D, and a fluorosurfactant having a nonionic organic head and a tail of the formula CF.sub.3 --(CF.sub.2).sub.x --CH.sub.2 CH.sub.2, where x is an integer from 3 to 15.

BACKGROUND 
1. Field of the Invention 
This invention relates to the field of polymers, and specifically polymers 
that include at least one copolyetherester elastomer. 
2. Description of the Related Art 
Copolyetherester elastomers and methods for their preparation are known in 
the art. Copolyetherester elastomers combine many of the most desirable 
characteristics of high-performance elastomers and flexible plastics. 
Copolyetherester elastomers are block polymers that include a hard, or 
crystalline, segment and a soft, or amorphous, segment based on long-chain 
polyether glycols. Properties are determined by the ratio of soft segments 
and by the makeup of these segments. 
These elastomers also feature exceptional toughness and resilience; high 
resistance to creep, impact and flex fatigue; flexibility at low 
temperatures; and good retention of properties at elevated temperatures. 
Copolyetherester elastomers may be readily formed into high-performance 
products by a variety of thermoplastic processing techniques, including 
injection molding, extrusion, blow molding, rotational molding and melt 
casting. 
A problem with molded parts made from copolyetherester elastomers sometimes 
arises when those molded parts are subjected to a scratching or scuffing 
force in that those forces leave visible scratches or scuff marks on the 
surface of the molded part. These scratches and scuff marks are 
undesirable when the molded part is visible in normal use, such as when 
the molded part is an air bag deployment door or dashboard of an 
automobile. 
What is necessary, therefore, is a polymer composition that includes a 
copolyetherester elastomer and that is resistant to scratching and 
scuffing. 
SUMMARY OF THE INVENTION 
The present invention relates to a scratch resistant polymer composition 
having a polymer that includes a copolyetherester elastomer, said polymer 
having a hardness of from 25D to 82D, and a fluorosurfactant having a 
nonionic organic head and a tail of the formula CF.sub.3 
--(CF.sub.2).sub.x --CH.sub.2 CH.sub.2, where x is an integer from 3 to 
15. 
DETAILED DESCRIPTION 
The present invention relates to a scratch resistant polymer composition 
having (a) from 99 to 99.9 weight percent of a polymer that includes a 
copolyetherester elastomer, said polymer having a hardness of from 25D to 
82D, and (b) from 0.1 to 1 weight percent of a fluorosurfactant having a 
nonionic organic head and a tail of the formula CF.sub.3 
--(CF.sub.2).sub.x --CH.sub.2 CH.sub.2, where x is an integer from 3 to 
15, based on the total weight of (a) and (b) only. 
The polymer of the present invention includes a copolyetherester elastomer 
or a mixture of two or more copolyetherester elastomers. Optionally, the 
polymer may also include polystyrene, polyethylene terephthalate, 
polybutylene terephthalate, acrylonitrile butadiene styrene, styrene 
acrylonitryle, polycarbonate, polypropylene modified with 
ethylene-propylene-diene terpolymer (EPDM), or mixtures thereof. The 
copolyetherester elastomer should be present in the polymer in an amount 
of at least 30 weight percent. 
By "copolyetherester elastomer" or "a mixture of two or more 
copolyetherester elastomers" is meant a copolyetherester elastomer such as 
is disclosed in U.S. Pat. Nos. 3,766,146, 4,014,624 and 4,725,481. These 
patents disclose a segmented thermoplastic copolyetherester elastomer 
containing recurring polymeric long chain ester units derived from 
carboxylic acids and long chain glycols and short chain ester units 
derived from dicarboxylic acids and low molecular weight diols. The long 
chain ester units form the soft segment of the copolyetherester elastomer, 
and the short chain ester units form the hard segment. 
More specifically, such copolyetherester elastomers may comprise a 
multiplicity of recurring intralinear long chain and short chain ester 
units connected head-to-tail through ester linkages, said long chain ester 
units being represented by the formula: 
##STR1## 
and said short-chain ester units being represented by the formula: 
##STR2## 
wherein: 
G is a divalent radical remaining after removal of terminal hydroxyl groups 
from poly(alkylene oxide) glycols having a carbon to oxygen ratio of about 
2.0-4.3, a molecular weight above about 400 and a melting point below 
about 60.degree. C.; 
R is a divalent radical remaining after removal of carboxyl groups from a 
dicarboxylic acid having a molecular weight less than about 300; and 
D is a divalent radical remaining after removal of hydroxyl groups from a 
low molecular weight diol having a molecular weight less than about 250. 
It is preferred that the short chain ester units constitute about 15-95% by 
weight of the copolyester and at least about 50% of the short chain ester 
units be identical. 
The term "long chain ester units" as applied to units in a polymer chain 
refers to the reaction product of long chain glycol with a dicarboxylic 
acid. Such "long chain ester units", which are a repeating unit in the 
copolyesters, correspond to the formula (I) above. The long chain glycols 
are polymeric glycols having terminal (or as nearly terminal as possible) 
hydroxyl groups and a molecular weight above about 400 and preferably from 
about 400-4000. The long chain glycols used to prepare the copolyesters 
are poly(alkylene oxide) glycols having a carbon to oxygen ratio of about 
2.0-4.3. Representative long chain glycols are poly (1,2- and 
1,3-propylene oxide) glycol, poly(tetramethylene oxide) glycol, random or 
block copolymers of ethylene oxide and 1,2-propylene oxide. 
The term "short chain ester units" as applied to units in a polymer chain 
refers to low molecular weight compounds or polymer chain units having 
molecular weights less than about 550. They are made by reacting a low 
molecular weight diol (below about 250) with a dicarboxylic acid to form 
ester units represented by formula (II) above. 
Included among the low molecular weight diols which react to form short 
chain ester units are acyclic, alicyclic and aromatic dihydroxyl 
compounds, an example of which is 1,4-butanediol. Dicarboxylic acids which 
are reacted with the foregoing long chain glycols and low molecular weight 
diols to produce the copolyesters of this invention are aliphatic, 
cycloaliphatic or aromatic dicarboxylic acids of low molecular weight, 
that is, having a molecular weight of less than about 300, an example of 
which is terephthalic acid. 
The polymer of the invention has a hardness of from 25D to 82D. As used 
herein, the term "hardness" means the hardness of a polymer as determined 
by International Standard ISO 868-1978(E). The hardness measured by this 
Standard is also known as "Shore hardness". Hardness measurements 
according to this standard are followed by either the letter A or D to 
indicate whether a type A or type D Shore durometer was used to make the 
hardness measurement. 
The scratch resistant polymer composition also includes from 0.1 to 1 
weight percent of a fluorosurfactant. Fluorosurfactants are anionic, 
nonionic or cationic fluoro alkyl compounds that have extremely low 
surface tension and are used as wetting, emulsifying and dispersing 
agents. The fluorosurfactant according to the present invention has a 
nonionic organic head and a tail of the formula CF.sub.3 
--(CF.sub.2).sub.x --CH.sub.2 CH.sub.2, where x is an integer from 3 to 
15. The nonionic organic head may be an alkenyl or a compound of the 
formula (O--CH.sub.2 --CH.sub.2).sub.y --OH, where y in an integer from 1 
to 10. Further, the fluorosurfactant may be present in a solvent system, 
such as an ethylene glycol/water solvent system. 
The fluorosurfactant is normally present in the form of a viscous liquid, 
and may be added to the polymer using any conventional method,, such as 
directly injecting the fluorosurfactant into a compounding machine that 
includes the polymer. 
The weight ranges for the inventive polymer given above based on the total 
weight of (a) a polymer that includes a copolyetherester elastomer and (b) 
a fluorosurfactant having a nonionic organic head and a tail of the 
formula CF.sub.3 --(CF.sub.2).sub.x --CH.sub.2 CH.sub.2, where x is an 
integer from 3 to 15, based on the total weight of (a) and (b) only. 
The polymer may be compounded with antioxidant stabilizers, ultra-violet 
stabilizers, hydrolysis stabilizers, dyes or pigments, fillers such as 
mineral fillers, anti-microbial reagents, and the like.

EXAMPLES 
In the following examples, various polymer compositions were tested for 
scratch resistance and scuffing resistance. The results of these examples 
are summarized in Tables 1-5 below. 
The polymer composition included a copolyetherester elastomer, carbon black 
and a fluorosurfactant. Carbon black was added to make the molded polymer 
black, and which made it easier to detect scratches and scuffs in the 
molded polymer. 
In each example the polymer composition was prepared by preblending pellets 
of the copolyetherester elastomer with a fluorosurfactant. The preblended 
pellets were combined with additional copolyetherester elastomer pellets 
in a compounder and were compounded into a molten resin. The molten resin 
was cooled in a water bath and cut into pellets. The pellets were then 
dried to reduce the moisture content to below 0.1 weight percent. The 
dried pellets were injection molded to form a plate that had both a glossy 
surface and a mat surface. The mat surface had a texture roughness that 
corresponded to Charmilles 12 with a roughness number Ra of 0.4 microns. 
The fluorosurfactants used in the examples according to the invention were 
Zonyl.RTM. FSO 100 and Zonyl.RTM. 8857A, available from DuPont. Zonyl.RTM. 
FSO 100 is a non ionic fluorosurfactant having a tail of the formula 
CF.sub.3 --(CF.sub.2).sub.x --CH.sub.2 CH.sub.2, where x is an integer 
from 3 to 15 and a head of the formula (O--CH.sub.2 --CH.sub.2).sub.y 
--OH, where y in an integer from 1 to 10. The Zonyl.RTM. FSO 100 is 
present in a concentration of 50 percent in an ethylene glycol/water 
solvent system. Zonyl.RTM. 8857A is a non ionic fluorosurfactant having a 
tail of the formula CF.sub.3 --(CF.sub.2).sub.a --CH.sub.2 CH.sub.2, where 
a is an integer from 3 to 15 and an alkenyl head. There was no solvent 
present in Zonyl.RTM. 8857A. 
Scratch resistance of both the glossy and mat surfaces of the molded plate 
was measured by a modified ISO 1518 test using an Erichsen scratch tester. 
The ISO 1518 standard is a test for scratching paint where a pin is 
subjected to a load and then placed in contact with a painted surface 
where the pin is dragged on the surface at a constant speed of 30 
millimeters per second. The same test procedure was used for these 
examples except that a molded plate was used in place of a painted 
surface. The pin was subjected to higher and higher loads until the 
surface of the molded plate was scratched, at which point the load was 
recorded. While higher loads on the pin caused deeper grooves in the 
molded plate, the plate was considered to be scratched only when the load 
on the pin was high enough to cause microcutting on the plate visible to 
the naked eye, that is, when cuts perpendicular to the axis of the scratch 
line were formed in the surface of the plate. 
Scuffing resistance of both the glossy and mat surfaces of the molded plate 
was measured by the following method. A measuring device was used that 
included a horizontal table supporting the molded plate; a vertical 
cylinder supporting an horizontal arm able to have a rotational motion 
around the cylinder; a vertical pin having a total weight of about 295 
grams fixed a the free end of the horizontal arm, the pin having a 
cylindrical shape with a diameter of 1.2 mm with rounded edge, and an 
angular displacement limited at both ends by a block; and a cylindrical 
spring made of steel having a stiffness of about 0.2N/mm. This spring was 
fixed between the free end of the horizontal arm and one end of the block, 
and was used to move the vertically-loaded pin with a constant force. The 
angular motion speed of the pin depended of the friction coefficient of 
the material of the molded plate. 
The scuffing resistance of the molded plate was measured as follows. The 
molded plate of the material to be tested was fixed onto the horizontal 
table, and the loaded pin was attached to the horizontal arm so that there 
was no contact between the plate and the tip of the pin. The horizontal 
arm was rotated to the maximum angle possible, to give the maximum force 
from the spring according the limited angular displacement of this arm. 
The loaded pin was placed in contact with the test plate and then the arm 
holding the pin was released and the force exerted by the spring allowed 
the pin to follow an angular displacement on the surface of the molded 
plate to scuff the surface of the molded plate. 
The angular motion of the loaded pin produced a visible scuffing line on 
the surface of the test plate, depending on the weight of the pin. The 
load on the pin was adjusted to give invisible scuffing line on a 
reference material defined as the target material. The constant value of 
load should give a visible scuffing line on the material to be improved as 
far as scratch resistance is concerned. 
The scale of scuffing resistance in Table 1 is rated in a range of from 0 
to 5, where 0 represents no or an invisible scuffing line, and 5 
represents a significant amount of scuffing. 
COMATIVE EXAMPLE 1 AND EXAMPLES 2-5 
In Comparative Example 1, a polymer composition was made using 0.4 weight 
percent carbon black and 99.6 weight percent of copolyetherester elastomer 
having a hard segment of 4-glycol terephthalate (4GT) and a soft segment 
of polypropylene glycol (PPG) and a hardness of 35D. The elastomer is sold 
by DuPont under the trademark Hytrel.RTM. G3548L. 
In Examples 2 and 3 a polymer composition was made as in Comparative 
Example 1 using 0.4 weight percent carbon black, except that the 
composition also included Zonyl.RTM. FSO 100 fluorosurfactant. In Examples 
4 and 5 a polymer composition was made as in Examples 2 and 3 except that 
the composition included Zonyl.RTM. 8857A fluorosurfactant. 
The results of these examples showed that the compositions in Examples 2-5 
all showed an increase in scratch resistance compared to the composition 
in Comparative Example 1. Similarly, all the compositions in these 
examples, except for the glossy side of the molded plate of example 2, all 
showed an increase in scuffing resistance compared to the composition in 
Comparative Example 1. 
COMATIVE EXAMPLE 6 AND EXAMPLES 7-8 
Compositions were made as in the previous Comparative Example 1 and 
examples 4-5 except that the polymer had a hardness of 55D. The elastomer 
is sold by DuPont under the trademark Hytrel.RTM. G5544. 
The results of these examples showed that the compositions in Examples 7-8 
all showed a significant increase in both scratch resistance and scuffing 
resistance compared to the composition in Comparative Example 6. 
COMATIVE EXAMPLES 9 AND EXAMPLES 10-11 
Compositions were made as in the previous Comparative Example 1 and 
Examples 4-5 except that the polymer used was a copolyetherester elastomer 
having a hard segment of 4GT and a soft segment of polytetra methylene 
ether glycol (PTMEG) and a hardness of 55D. The elastomer is sold by 
DuPont under the trademark Hytrel.RTM. 5556. 
The results of these examples showed that the compositions in Examples 
10-11 all showed an increase in both scratch resistance, and scuffing 
resistance on the mat side of the molded plate, compared to the 
composition in Comparative Example 9. 
COMATIVE EXAMPLES 12 AND EXAMPLES 13-14 
Compositions were made as in the previous Comparative Example 1 and 
Examples 4 and 5 except that the polymer used was a copolyetherester 
elastomer having a hard segment of 4GT and a soft segment of PTMEG and a 
hardness of 72D. The elastomer is sold by DuPont under the trademark 
Hytrel.RTM. 7246. 
The results of these examples showed that the compositions in Examples 
13-14 showed an increase in scratch resistance when the surface of the 
molded plate was glossy. 
COMATIVE EXAMPLES 15 AND EXAMPLES 16-17 
Compositions were made as in the previous Comparative Example 1 and 
Examples 2 and 4 except that the polymer had a hardness of 40D. The 
elastomer is sold by DuPont under the trademark Hytrel.RTM. G4044. 
The results of these examples showed that the compositions in Examples 
16-17 showed an increase in both scratch resistance and scuffing 
resistance compared to the compositions in Comparative Example 15. 
TABLE 1 
__________________________________________________________________________ 
Scratch 
Resistance.sup.1 
Scuffing Resistance.sup.2 
Ex. wt. 
(N) AT GATE AT END 
No. 
Fluorosurfactant 
% GLOSSY 
MAT 
GLOSSY 
MAT 
GLOSSY 
MAT 
__________________________________________________________________________ 
C1 None 8 9 5 5 5 5 
2 Zonyl .RTM. FSO100 
0.3 
12 12 5 2 5 2 
3 Zonyl .RTM. FSO100 
0.6 
13 13 0.5 0.5 
0.5 0.5 
4 Zonyl .RTM. 8857A 
0.1 
13 11 4 1 4 0.5 
5 Zonyl .RTM. 8857A 
0.3 
14 14 0.5 0.5 
0.5 0.5 
C6 None 9 3 2 3 2 
7 Zonyl .RTM. 8857A 
0.1 
20- 19 0 0.5 
0 0 
8 Zonyl .RTM. 8857A 
0.3 
20+ 20 0.5 0 0.5 0 
C9 None 12 12 0 3 0.5 3 
10 Zonyl .RTM. 8857A 
0.1 
19 20 0 0.5 
0.5 0.5 
11 Zonyl .RTM. 8857A 
0.3 
19 20 0.5 0.5 
0.5 0.5 
C12 
None 10 18 0.5 0.5 
0.5 1 
13 Zonyl .RTM. 8857A 
0.1 
17 18 0.5 1 0.5 0.5 
14 Zonyl .RTM. 8857A 
0.3 
17 18 0.5 1 0.5 0.5 
C15 
None 5 8 5 5 5 5 
16 Zonyl .RTM. FSO100 
0.3 
15 14 0 1 0 1 
17 Zonyl .RTM. 8857A 
0.1 
16 14 0 1 0.5 1 
__________________________________________________________________________ 
.sup.1 Force on pin required to produce scratching. 
.sup.2 0 represents no or an invisible scuffing line, and 5 represents a 
significant amount of scuffing 
COMATIVE EXAMPLES 18 AND EXAMPLES 19-20 
In Comparative Example 18 the physical properties of the composition of 
Comparative Example 15 was measured, and in Examples 19 and 20 the 
physical properties of the composition of Examples 16 and 17 were 
measured. The results of these examples, summarized in Tables 2-5 below, 
showed that the addition of the fluorosurfactant does not adversely affect 
the physical properties of the polymer composition. 
The data for stress, strength and strain were all measured according to ISO 
527, and the data for tear strength were measured according to ISO 34A. 
The data for shrinkage in Table 5 were measured as follows: a molded plate 
was made under standard molding conditions and was kept at room 
temperature for 24 hours. Then the length of the plate was measured in 
both the in-flow and cross-flow directions, and this length was compared 
to the length of the mold cavity in the in-flow and cross-flow directions. 
"In-flow" direction means along the direction of flow of resin into the 
mold, and "cross-flow" direction means perpendicular to the direction of 
flow of resin into the mold. 
TABLE 2 
______________________________________ 
Tensile Properties at +23 C 
Ex. Stress @ 10% 
Strength @ 
Strain at break 
Tear Strength 
No. strain (MPa) 
break (MPa) 
(%) (N/mm) 
______________________________________ 
C18 4 21 &gt;500 47 
19 4.3 19.2 &gt;500 50 
20 4.3 20.3 &gt;500 47 
______________________________________ 
TABLE 3 
______________________________________ 
Tensile Properties at -40 C 
Stress @ 10% 
Strength @ 
Strain at break 
Tear Strength 
Ex. No. 
strain (MPa) 
break (MPa) 
(%) (N/mm) 
______________________________________ 
C18 20.1 29 210 145 
19 16.6 26.4 180 140 
20 14.5 26.5 180 150 
______________________________________ 
TABLE 4 
______________________________________ 
Tensile Properties at +85 C 
Stress @ 10% Strength @ 
Strain at 
Ex. No. strain (MPa) break (MPa) 
break (%) 
______________________________________ 
C18 2.5 12 &gt;500 
19 2.6 11.9 &gt;500 
20 2.9 12 &gt;500 
______________________________________ 
TABLE 5 
______________________________________ 
shrinkage 
in flow (%)/ 
Example No. cross flow (%) 
______________________________________ 
C18 0.8/1.0 
19 0.7/0.9 
______________________________________