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
1998-06-16
2002-12-17
Buttner, David J. (Department: 1712)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Mixing of two or more solid polymers; mixing of solid...
C525S323000, C526S065000, C526S124600, C526S125300, C526S128000, C526S129000, C526S142000, C526S348000
Reexamination Certificate
active
06495634
ABSTRACT:
The invention relates to propylene polymers containing a matrix of a propylene homopolymer and a copolymer of propylene and other alkenes, wherein, during the separation of the propylene polymers according to tacticity and comonomer distribution of the polymer chains, by first dissolving the propylene polymers in boiling xylene, then cooling the solution at a cooling rate of 10° C./h to 25° C. and thereafter, increasing the temperature, separating the propylene polymers into fractions of different solubility, either one or more of the conditions that
i) more than 20% by weight of the matrix remain undissolved on further heating to 112° C. or
ii) more than 8% by weight of the matrix remain undissolved on further heating to 117° C. or
iii) more than 1% by weight of the matrix remain undissolved on further heating to 122° C.
are fulfilled by the matrix which remains undissolved on heating the cooled propylene polymer solution to 80° C.
The present invention furthermore relates to a process for the preparation of the propylene polymers, their use for the production of films, fibers or moldings and films, fibers or moldings comprising these propylene polymers.
The unpublished German patent application P 197 10 761.3 describes propylene homopolymers which have particularly high crystallinity and are prepared using a catalyst system containing a titanium-containing solid component, an aluminum compound and an electron donor compound.
Propylene/ethylene copolymers obtainable by polymerization over Ziegler-Natta catalysts have been described in many patents. U.S. Pat. No. 4,260,710 discloses the preparation of homo- and copolymers of alk-1-enes by polymerization with the aid of Ziegler-Natta catalysts in a stirred kettle. The catalyst components used contain, inter alia, compounds of polyvalent titanium, aluminum halides and/or alkylaluminum as well as electron donor compounds, silanes, esters, ethers, ketones or lactones generally being used (EP-B 14 523, EP-B 45 977, EP-B 86 473, U.S. Pat. No. 857,613, EP-A 171 200).
Furthermore, a number of processes for the preparation of propylene/ethylene block copolymers with the aid of a Ziegler-Natta catalyst system are known (U.S. Pat. No. 4,454,299, U.S. Pat. No. 4,455,405, ZA-B 0084/3561, ZA-B 0084/3563, ZA-B 0084/5261, GB-B 1 032 945, DE-A 38 27 565), in which first gaseous propylene is polymerized in a first reaction zone and the homopolymer obtainable therefrom is then brought into a second reaction zone where a mixture of ethylene and propylene is polymerized thereon. The process is usually carried out at superatmospheric pressure and in the presence of hydrogen as a molecular weight regulator. The copolymers obtainable generally have good impact strength and rigidity.
By varying the amount of the homopolymer obtained in the first stage and of the copolymer to be polymerized on in the second stage, it is possible to control the impact strength of the propylene/ethylene block copolymers. However, inevitably a decrease in the rigidity is associated with an increase in the impact strength and, conversely, a decrease in the impact strength with an increase in the rigidity. For some applications of plastics, however, it is necessary to increase the rigidity without reducing the impact strength or to improve the impact strength without reducing the rigidity. Moreover, the polymers should have a very low chlorine content and, for economic reasons, a further increase in the productivity of the catalyst system used is of interest.
It is an object of the present invention to provide propylene polymers which have a further improved ratio of rigidity to toughness, possess a low chlorine content and furthermore can be prepared by a process with increased productivity.
We have found that this object is achieved by the propylene polymers defined at the outset and a process for their preparation, their use for the production of films, fibers or moldings and the films, fibers or moldings comprising these propylene polymers.
The novel propylene polymers are generally present in a form comprising at least two phases. They contain a continuous phase of a propylene homopolymer, which is referred to as the matrix. This matrix phase is semicrystalline, ie. it consists of a crystallized fraction, ie. the crystallites, and an amorphous fraction. According to the invention, the term propylene homopolymer is also intended to mean those propylene polymers in which minor amounts of other alkenes are copolymerized units, the propylene homopolymers generally containing less than 2, in particular less than 1, % by weight of other alkenes. The matrix of the novel propylene homopolymers preferably contains only propylene as a monomer.
The novel propylene polymers preferably contain from 50 to 92% by weight of the matrix-forming propylene homopolymer. Particularly preferably, the amount of the matrix is from 60 to 90% by weight.
Furthermore, the novel propylene polymers contain a copolymer of propylene and other alkenes, which is present as a separate phase from the matrix and exhibits very low or no crystallinity. This copolymer referred to as a rubber or elastomer contains, as a rule, from 20 to 85% by weight of propylene. The propylene content of the copolymer is preferably from 35 to 80, in particular from 45 to 70, % by weight. Depending on the chosen ratio of matrix to elastomer, the phase of the copolymer of propylene and other alkenes is present in disperse form in the matrix or is likewise continuous and hence cocontinuous with the matrix.
The other alkenes which are copolymerized with propylene are to be understood as meaning preferably alk-1-enes of up to 10 carbon atoms. Ethylene, but-1-ene, pent-1-ene, hex-1-ene, hept-1-ene and oct-1-ene or mixtures of these comonomers are particularly suitable, ethylene and but-1-ene being preferred. In the case of the copolymers acting as elastomers, unconjugated dienes, such as ethylidenenorbornene, dicyclopentadiene or 1,4-hexadiene, may also be present as other alkenes and are then copolymerized, as a rule, with ethylene and propylene.
The novel propylene polymers preferably contain from 8 to 50% by weight of the copolymer of propylene and other alkenes. Particularly preferably, the amount of the elastomer phase is from 10 to 40% by weight.
In addition to the essential components, the novel propylene polymers may also contain further homo- or copolymers of alkenes, for example homo- or copolymers of ethylene or polyisobutylene. For example, the amount of the further homo- or copolymers of alkenes may be from 0 to 30% by weight, based on the total propylene polymer.
One method for analyzing propylene polymers with regard to the fractions of polymer chains of different tacticity and different comonomer incorporation is TREF (Temperature Rising Elution Fractionation), in which the dissolution temperature of the polymer fraction corresponds to its average length of sequences built up without defects. To carry out the TREF, the propylene polymers are first dissolved in hot, preferably boiling xylene, the solution is then cooled at a constant cooling rate and thereafter the propylene polymers are separated, with increasing temperature, into fractions of different crystallinity. The composition of the propylene polymers can be described in terms of the fraction which remains undissolved on heating the cooled propylene polymer solution to a defined temperature.
In the fractionation of mixtures of propylene homopolymers and copolymers of the propylene with other alkenes, the polymer chains composed of different monomers first go into solution with increasing dissolution temperature, the dissolution temperature being lower the shorter the average sequence lengths of a monomer type. This means that first the elastomer fraction goes into solution and then, at higher temperatures, the matrix, which can be separated again with regard to the average isotactic sequence length of the polymer chains. It has been found that the polymer fractions which go into solution up to and including 80° C. can be assigned to the elastomer phase, whe
Hingmann Roland
Hüffer Stephan
Langhauser Franz
Lilge Dieter
Rösch Joachim
BASF - Aktiengesellschaft
Buttner David J.
Keil & Weinkauf
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