Thermoplastic elastomers

Details Thermoplastic elastomers Thermoplastic elastomers

2000-01-04

2001-10-09

Hampton-Hightower, P. (Department: 1711)

Synthetic resins or natural rubbers -- part of the class 520 ser

Synthetic resins

From carboxylic acid or derivative thereof

C528S272000, C528S288000, C528S300000, C528S302000, C528S322000, C528S332000, C528S335000, C528S336000, C428S357000, C428S394000, C428S395000, C525S09200D, C525S420000, C525S425000

Reexamination Certificate

active

06300463

ABSTRACT:

FIELD OF THE INVENTION
Thermoplastic elastomeric polymers which contain polyether blocks having tetramethylene ether repeat units, and polyamide blocks, have improved elastomeric properties such as higher unload power and lower tensile set, when the polyether blocks also contain 2-alkyltetramethylene ether repeat units.
BACKGROUND OF THE INVENTION
Thermoplastic elastomers (TPE) are a class of polymers which combine the properties of two other classes of polymers, namely thermoplastics which may be reformed upon heating, and elastomers which are rubber-like polymers. One form of TPE is a block copolymer, usually containing some blocks whose polymer properties usually resemble those of thermoplastics, and some blocks whose properties usually resemble those of elastomers. Those blocks whose properties resemble thermoplastics are often referred to as “hard” blocks, while those blocks whose properties resemble elastomers are often referred to as “soft” blocks. In such TPEs, the hard blocks are believed to take the place of chemical crosslinks in traditional thermosetting elastomers, while the soft blocks provide the rubber-like properties.
The polymeric nature of the hard and soft blocks of a TPE, as well as the number of such blocks and their size (length) determines to a great extent the properties of the resulting TPE. For example, longer soft blocks usually lead to TPEs having lower initial tensile modulus, while a high percent of hard blocks leads to polymers with higher initial tensile modulus. Other properties may be affected as well. Thus manipulation on the molecular level changes the properties of TPE's, and improved TPEs are constantly being sought.
U.S. Pat. Nos. 4,331,786 and 4,230,838 describe certain poly(ether-ester-amides) which may contain polyether blocks containing tetramethylene ether repeat units. No specific mention is made of polymers containing 2-alkyltetramethylene ether repeat units.
U.S. Pat. No. 4,937,314 describes poly(ether-esters) in which a polyether soft block contains tetramethylene ether and 2-methyltetramethylene ether repeat units. No mention is made of the use of such soft blocks in poly(ether-ester-amides).
What are needed are improved thermoplastic elastomers which do not have the deficiencies of the prior art. Other objects and advantages of the present invention will become apparent to those skilled in the art upon reference to the detailed description of the invention which hereinafter follows.
SUMMARY OF THE INVENTION
This invention concerns a polymer, comprising, the repeat units:
(a) —R
2
C(O)O{[—CH
2
)
4
O—]
m
[—CH
2
CHR
1
CH
2
CH
2
O—]
n
}C(O)R
2
— (I); and
(b) one or both of
(i) —C(O)[—NHR
3
NHC(O)R
2
C(O)—]
q
HNR
3
NHC(O)— (II), and
(ii) —C(O)[—NHR
4
C(O)—]
t
NH— (III);
wherein:
each R
1
independently is alkyl containing 1 to 6 carbon atoms;
each R
2
, R
3
and R
4
independently is saturated hydrocarbylene or substituted saturated hydrocarbylene containing 2 to 20 carbon atoms, or hydrocarbylidene or substituted hydrocarbylidene containing 1 to 20 carbon atoms;
m is an integer from 5 to about 150;
n is 0 or an integer of 1 to about 50, provided that the overall ratio of m
in said polymer is about 3 to about 30;
q is 0 or an integer of 1 to about 20; and
t is 0 or an integer of 1 to about 20.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
Certain terms used herein are defined below:
By “saturated hydrocarbylene” is meant a moiety containing only carbon and hydrogen having two open valencies, one each to two different carbon atoms. The carbon atoms containing the open valencies are saturated, i.e., have no multiple bonds to those carbon atoms, but these carbon atoms may be parts of other groups such as rings. The other part of the saturated hydrocarbylene group, if any, may contain multiple bonds such as olefinic bonds or aromatic rings.
By hydrocarbyl is meant a univalent radical containing only carbon and hydrogen.
By “hydrocarbylidene” is meant a group containing only carbon and hydrogen and having two free valencies to a single carbon atom which itself has no multiple bonds attached to it. The hydrocarbylidene carbon atom may be part of another structure, such as part of a ring. Other parts of the hydrocarbylidene group may contain multiple bonds, such as olefinic bonds or aromatic rings.
By a group or compound being “substituted” herein means that the groups may contain one or more atoms other than carbon and hydrogen which are, or are part of, functional groups. These functional groups should not interfere with the formation of the desired polymers, and such groups are generally known one of ordinary skilled in art to the artisan. Suitable functional groups include ether, halo, sulfone, and nitrogen containing aromatic heterocyclic rings.
The polymers described herein have certain repeat units which form part of the polymer. Small amounts of other repeat units may also be present in these polymers so long as the essential character of the polymer is not changed. Among these other repeat units may be branching agents, which are tri- or higher functional compounds such as triamines, trihydroxy compounds, or tricarboxylic acids, even though these branching agents may change the rheological properties of the resulting polymer. Trifinctional compounds are preferred as branching agents.
One of these repeat units is (I), which forms the soft block of the polymer. As will be understood by the artisan, (I) is formed by a random copolymerization of tetrahydrofuran (THF) and 3-alkyltetrahydrofuran which leads to subrepeat units [—(CH
2
)
4
O—] and [—CH
2
CHR
1
CH
2
CH
2
O—], respectively. Therefore, in (I) [—(CH
2
)
4
O—] and [—CH
2
CHR
1
CH
2
CH
2
O—] are randomly placed within the structure. Since [—CH
2
CHR
1
CH
2
CH
2
O—] is the minor molar fraction of (I), it is possible that in certain (I) units, there will be no subrepeat units of the formula [—CH
2
CHR
1
CH
2
CH
2
O—]. In another possible combination, a homopolymer of the subrepeat unit [—(CH
2
)
4
O—] is combined with a copolymer of both of the subrepeat units of (I). However in any event on average (I) must contain sufficient subrepeat units [—CH
2
CHR
1
CH
2
CH
2
O—] so that the limitation on the ratio m
is met.
In (I) R
1
may be methyl, ethyl, i-propyl, etc., but it is preferred that R
1
is methyl. It is also preferred that m is about 7 to about 50, and/or the overall ratio of m
is 4 to about 20.
In all of the repeat units it is preferred that R
2
, R
3
and R
4
are each independently saturated hydrocarbylene, more preferably alkylene or cycloalkylene, and it is most preferred —(CH
2
)
r
— wherein r is 2 to 18. Useful saturated hydrocarbylene groups (which may be alkylene or cycloalkylene) include 2-methyl-1,4-pentylene, 1,6-hexylene, 1,4-butylene, m- or p-xylylene, 1,4-cyclohexylene, 1,12-dodecylene, 1,2-ethylene, 1,10-decylene and 1,8-octylene. Especially preferred combinations of R
2
and R
3
are: when R
2
is 1,10-decylene, R
3
is 1,6-hexylene; and when R
2
is 1,4-butylene and R
3
is 1,10-decylene.
In (II) it is preferred that q is 0 to about 6, and in (III) it is preferred that t is 0 or 1 to about 6. While (II) and (III) may be present in the same polymer, it is preferred that either (II) or (III) is present in the polymer.
Because of the end groups on repeat units (I), (II) and (III), it will be recognized that within the poly(ether-ester-amide) the end groups of (II) and (III) must be bound to the end groups of (I), so that in essence the blocks of (I) will alternate (if enough of such blocks are present) with blocks of (II) and/or (III). While the end groups of the overall polymer molecules are not critical, they will normally be monofunctional groups such as —OH, —NH
2
, CO
2
H.
These poly(ether-ester-amides) may be made by known methods, see for instance U.S. Pat. Nos. 4,230,838, 4,331,786, 4,252,920, 4,208,493, and 5,444,120, and S. Fakirov, et al., Makromol. Chem., vol. 193, p. 2391-2404 (1992), all of which are

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