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
2000-05-22
2002-09-03
Mullis, Jeffrey (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...
C525S314000, C525S316000
Reexamination Certificate
active
06444755
ABSTRACT:
BACKGROUND
Copolymers of conjugated diene/monovinylarene are known and useful for a variety of purposes. Of particular interest are polymers that can be formed into colorless, transparent articles having good physical properties, such as impact resistance. Such articles are useful in toys, window pieces, beverage containers, and packaging such as blister packaging.
The polymers should also exhibit sufficient thermal stability to be suitable for use with conventional injection molding equipment. For many applications copolymer blends containing high amounts of styrene are required. Such polymers are generally prepared by blending certain monovinylarene-conjugated diene copolymers with styrene polymers. However such blends often contain an undesirable haze and blue coloration. It would therefore be desirable to develop polymers and polymer blends having a combination of low blueness, good clarity, hardness, stiffness, and toughness.
SUMMARY OF THE INVENTION
It is an object of this invention to provide a polymer useful for preparing blends having good optical clarity.
It is another object of this invention to provide a polymer useful for preparing blends having low blueness.
It is another object of this invention to provide a process for preparing such polymers having good optical and mechanical properties.
In accordance with this invention a block copolymer comprising at least three consecutive conjugated diene/monovinylarene tapered blocks is provided. As used herein, consecutive means three sequential tapered blocks with no intervening homopolymer blocks. The tapered blocks contain a mixture of monovinylarene and conjugated diene.
In accordance with other aspects of this invention, a polymerization process for preparing the block copolymer and polymer blends comprising the block copolymer are provided.
DETAILED DESCRIPTION OF THE INVENTION
The basic starting materials and polymerization conditions for preparing conjugated diene/monovinylarene block copolymer are disclosed in U.S. Pat. Nos. 4,091,053; 4,584,346; 4,704,434; 4,704,435; and 5,227,419; the disclosures of which are hereby incorporated by reference.
Suitable conjugated dienes which can be used in the block copolymers include those having 4 to 12 carbon atoms per molecule, with those having 4 to 8 carbon atoms preferred. Examples of such suitable compounds include 1,3-butadiene, 2-methyl-1,3-butadiene, 2-ethyl-1,3-butadiene, 2,3-dimethyl-1,3-butadiene, 1,3-pentadiene, 3-butyl-1,3-octadiene, and mixtures thereof. The preferred dienes are 1,3-butadiene and isoprene, more preferably 1,3-butadiene.
Suitable monovinylarene compounds which can be used in the block copolymers include those having 8 to 18 carbon atoms per molecule, preferably 8 to 12 carbon atoms. Examples of such suitable compounds include styrene, alpha-methylstyrene, 2-methylstyrene, 3-methylstyrene, 4-methylstyrene, 2-ethylstyrene, 3-ethylstyrene, 4-ethylstyrene, 4-n-propylstyrene, 4-t-butylstyrene, 2,4-dimethylstyrene, 4-cyclohexylstyrene, 4-decylstyrene, 2-ethyl-4-benzylstyrene, 4-(4-phenyl-n-butyl)styrene, 1-vinylnaphthalene, 2-vinylnaphthalene, and mixtures thereof. Styrene is the preferred monovinylarene compound.
The relative amount of conjugated diene and monovinylarene in the block copolymer can vary broadly depending on the particular characteristics desired. Generally, the conjugated diene/monovinylarene block copolymer will contain monovinylarene monomer in an amount in the range of from about 55 weight percent to about 95 weight percent based on the total weight of the final block copolymer, preferably in the range of from about 60 weight percent to about 95 weight percent, and more preferably in the range of from 65 weight percent to 90 weight percent.
Generally the conjugated diene monomer will be present in the final block copolymer in an amount in the range of from about 45 weight percent to about 5 weight percent based on the total weight of the final block copolymer, preferably in the range of from about 40 weight percent to about 5 weight percent, and more preferably in the range of from 35 weight percent to 10 weight percent.
The inventive polymer contains at least three consecutive conjugated diene/monovinylarene tapered blocks, which are incorporated sequentially into the block copolymer with no intervening homopolymer blocks.
The amount of each monomer in the tapered block can vary broadly depending on the particular characteristics desired. Generally monovinylarene will be present in each tapered block in an amount in the range of from about one weight percent to about 20 weight percent based on the total weight of the final block copolymer, preferably from about 2 weight percent to about 15 weight percent.
Generally the conjugated diene will be present in each tapered block in an amount in the range of from about one weight percent to about 15 weight percent based on the total weight of the final block copolymer, preferably from about 2 weight percent to about 12 weight percent. It is especially preferred that all conjugated diene monomer present in the final block copolymer be incorporated into the tapered blocks.
The relative amount of each monomer in the tapered block can also vary broadly depending on the particular characteristics desired. Generally the conjugated diene will be present in each tapered block in an amount in the range of from about 0.1 parts to about 10 parts per part monovinylarene in the tapered block, preferably from about 0.2 parts to about 5 parts per part monovinylarene.
The monomer and monomer mixtures are copolymerized sequentially in the presence of an initiator. The initiators can be any of the organomonoalkali metal compounds known for such purposes. Preferably employed are compounds of the formula RM, wherein R is an alkyl, cycloalkyl, or aryl radical containing 4 to 8 carbon atoms, more preferably R is an alkyl radical. M is an alkali metal, preferably lithium. The presently preferred initiator is n-butyl lithium.
The amount of initiator employed depends upon the desired polymer or incremental block molecular weight, as is known in the art, and is readily determinable, making due allowance for traces of poisons in the feed streams. Generally the initiator will be present in an amount in the range of from about 0.01 phm (parts by weight per hundred parts by weight of total monomer) to about 1.0 phm, preferably about 0.01 phm to about 0.5 phm, and more preferably from 0.01 phm to 0.2 phm.
Small amounts of polar organic compounds, such as ethers, thioethers, and tertiary amines can be employed in the hydrocarbon diluent to improve the effectiveness of the initiator and to randomize at least part of the monovinylarene monomer in a mixed monomer charge. Tetrahydrofuran is currently preferred. When employed, the polar organic compound is present in an amount sufficient to improve the effectiveness of the initiator. For example, when employing tetrahydrofuran to improve the effectiveness of the initiator, the tetrahydrofuran is generally present in an amount in the range of from about 0.01 to about 1.0 phm, preferably from about 0.02 to about 1.0 phm.
The polymerization process is carried out in a hydrocarbon diluent at any suitable temperature in the range of from about −100° C. to about 150° C., preferably from 0° to 150° C., at pressures sufficient to maintain the reaction mixture substantially in the liquid phase. Preferred hydrocarbon diluents include linear or cycloparaffins or mixtures thereof. Typical examples include pentane, hexane, octane, cyclopentane, cyclohexane, and mixtures thereof. Cyclohexane is presently preferred. The polymerization is carried out in a substantial absence of oxygen and water, preferably under an inert gas atmosphere.
Each monomer charge or monomer mixture charge is polymerized under solution polymerization conditions such that the polymerization of each monomer charge or monomer mixture charge is substantially complete before charging a subsequent charge.
Typical initiator, monomer and monomer mixture charge sequences include, but are not limited to the followin
DePorter Craig D.
Moczygemba George A.
Stacy Nathan E.
Mullis Jeffrey
Owen Polly C.
Phillips Petroleum Company
LandOfFree
Conjugated diene/monovinylarene block copolymers blends does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Conjugated diene/monovinylarene block copolymers blends, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Conjugated diene/monovinylarene block copolymers blends will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2860262