Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Mixing of two or more solid polymers; mixing of solid...
Reexamination Certificate
1999-04-27
2001-07-10
Woodward, Ana (Department: 1711)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Mixing of two or more solid polymers; mixing of solid...
C525S183000
Reexamination Certificate
active
06258892
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to blends of alpha polyamides with functionalized elastomers. More particularly, this invention relates to blends of Nylon 6 and maleated star polymers with improved impact efficiency.
BACKGROUND OF THE INVENTION
Polyamides, known commercially as nylons, have excellent hardness, abrasion resistance, chemical resistance, and other mechanical properties, but suffer from being brittle. Many attempts have been made to make polyamides less brittle by blending them with impact modifiers such as rubbery polymers. For instance, U.S. Pat. No. 4,174,358 discloses the use of functionalized rubbers as impact modifiers for polyamides and U.S. Pat. Nos. 4,427,828 and 4,628,072 disclose the use of acid functionalized, hydrogenated block copolymers of styrene and dienes as similar impact modifiers. The inclusion of polar functional groups on the modifiers is generally considered to be necessary for the polyamides to be acceptably compatible with rubbers which do not otherwise contain polar functionality.
The use of acid derivative functionalized hydrogenated styrenic block copolymers as impact modifiers has been found to be particularly effective in modifying polyamides which are prepared by copolymerizing diamines and dicarboxylic acids, for example, Nylon 6,6. However, polyamides which are prepared by polymerizing monoaminocarboxylic acids or internal lactams thereof, such as Nylon 6, are more difficult to toughen with acid functionalized hydrogenated block copolymers.
U.S. Pat. No. 5,242,975 describes a process for producing impact modified blends of these functionalized block copolymers and nylons like Nylon 6 which are herein generally referred to alpha polyamides and have carboxylic acid or a derivative thereof as one terminal group and an amine as another terminal group. These alpha polyamides may be formed by ring-opening of lactams and polymerization of monoaminocarboxylic acids. The method of making a good impact modified Nylon 6 blend comprises blending a masterbatch which contains 15 to 120 parts of the alpha-polyamide and 100 parts of the functionalized block copolymer. This masterbatch is then later blended with a sufficient amount of the alpha-polyamide to result in a total of from 200 to 2000 parts by weight of the alpha-polyamide in the resultant toughened alpha-polyamide composition.
While the afore-mentioned masterbatch method works quite well, it does suffer from the following disadvantages: a specific extruder and feeder system is needed to be able to easily control the polymer feed rates and to maintain a constant blend composition. Therefore, it can be seen that it would be highly advantageous to be able to produce blends of alpha polyamides (Nylon 6) and functionalized block copolymers with excellent impact properties by direct blending. The present invention provides such compositions.
SUMMARY OF THE INVENTION
This invention is a toughened alpha-polyamide composition which has been admixed at a maximum shear rate of at least 400 sec
−1
and which comprises:
(a) 10 to 30, preferably 15 to 25, percent by weight (%wt) of an acid functionalized polydiene polymer,
(b) 60 to 89 % wt of an alpha-polyamide, and
(c) 1 to 10% wt of a polyamide prepared by copolymerizing a diamine and a dicarboxylic acid.
DESCRIPTION OF THE INVENTION
The polyamides useful in this invention as the main component, which will be referred to as alpha polyamides, include those polyamides which have one terminal amine and one terminal carboxylic acid group. This will be the case for polyamides which are formed by ring-opening of lactams and polymerization of monoamino carboxylic acids. Suitable polyamides are described in U.S. Pat. Nos. 2,071,250; 2,071,251; 2,241,322; and 5,242,975 which are incorporated herein by reference.
Examples of amino carboxylic acids include epsilon-amino caproic acid, and 3- and 4-amino benzoic acids. Examples of lactams include butyrolactam, pivalolactam, caprolactam, capryllactam, enantholactam, undecanolactam, and dodecanolactam. Illustrative examples of polyamides which may be used as a main component of the compositions of the present invention include polypyrrolidone (nylon-4), polycaprolactam (Nylon 6), polyheptolactam (nylon-7), polycapryl lactam (nylon-8), polynonanolactam (nylon-9), polyundecanolactam (nylon-11), and polydodecanolactam (nylon-12).
The acid functionalized hydrogenated conjugated diene polymer (polydiene) may be prepared by functionalizing an appropriate base polymer or by copolymerizing acid containing monomers, including anhydrides, with conjugated dienes, especially isoprene and/or butadiene. Other types of monomer units may also be incorporated into the polymer especially styrene and styrene derivatives which may form separate discrete blocks of, i.e., polystyrene or which may be randomly distributed throughout the polydiene polymer. These other types of monomer units may be incorporated in random, block, or tapered fashion. The amount of other monomers which may be incorporated into the polymer depends greatly on the properties of the polymers derived from these other monomers. These polymers are described in more detail in U.S. Pat. Nos. 5,242,975 and Re. 27,145 which are herein incorporated by reference.
The acid functionalized hydrogenated conjugated diene polymer may be of radial, linear, or branched configuration, but is preferably of a radial or star configuration. Linear polymers of functionalized conjugated diene polymers are also useful herein but are generally supplied as bales and not crumbs due to excessive cold-flow. The preferred radial or star acid functionalized hydrogenated polydiene polymer has from 3 to 30 arms extending from a suitable coupling agent. The diene polymer arms may be homopolymers or copolymers of conjugated dienes having from 4 to 12 carbon atoms, preferably isoprene and/or butadiene.
Any of the coupling agents known in the art to be useful in the production of radial polymers may be used in preparing the radial polymers of the present invention. Suitable coupling agents include those which are nonpolymerizable and which contain a fixed number of reactive sites, such as tetrachlorobenzene, carbon tetrachloride, and silicon tetrachloride. Coupling agents which are polymerizable are also acceptable, such as the polyalkenyl coupling agents like divinylbenzene taught in U.S. Pat. No. 3,985,830, Canadian Patent No. 716,645, and British Patent No. 1,025,295 which are all incorporated herein by reference.
Radial polymers useful as modifiers in the compositions of this invention may be prepared using the techniques described in U.S. Pat. Nos. 4,116,917 and 4,156,673 which are herein incorporated by reference. The conjugated diene polymer arms used in these s polymers will have a number average molecular weight within the range from about 200 to about 500,000. The radial polymer is usually hydrogenated so as to hydrogenate at least 90 percent of the initial ethylenic unsaturation contained in the polymer. Preferably, the hydrogenation will be greater than 98 percent. The hydrogenation can be accomplished as taught in U.S. Pat. No. 3,700,633 which is herein incorporated by reference.
When the base polymer does not contain acid derivative functionality, the functionality must be grafted onto the base polymer. In general, any carboxylic acid or derivative thereof having the ability to react with the base polymer in a free radical initiated reaction is useful to effect the modification needed for the compositions of the present invention. Useful modifying compounds may be polymerizable or nonpolymerizable compounds but are preferably nonpolymerizable or only slowly polymerizable.
While any acid or acid derivative which may be grafted or otherwise reacted with the hydrogenated radial polymer may be used, the compounds most commonly used contain ethylenic unsaturation. In general, essentially any acid or acid derivative could, initially, be incorporated into the base polymer so long as these groups can be conveniently converted to a functional group which will facilitate pe
Haas Donald F.
Shell Oil Company
Woodward Ana
LandOfFree
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