CA1210176A - Degradation of polypropylene for future improved processability - Google Patents
Degradation of polypropylene for future improved processabilityInfo
- Publication number
- CA1210176A CA1210176A CA000404450A CA404450A CA1210176A CA 1210176 A CA1210176 A CA 1210176A CA 000404450 A CA000404450 A CA 000404450A CA 404450 A CA404450 A CA 404450A CA 1210176 A CA1210176 A CA 1210176A
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- Prior art keywords
- prodegradant
- polypropylene
- polymer
- molecular weight
- butylperoxy
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
- C08J3/00—Processes of treating or compounding macromolecular substances
- C08J3/20—Compounding polymers with additives, e.g. colouring
- C08J3/22—Compounding polymers with additives, e.g. colouring using masterbatch techniques
- C08J3/226—Compounding polymers with additives, e.g. colouring using masterbatch techniques using a polymer as a carrier
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
- C08F8/00—Chemical modification by after-treatment
- C08F8/50—Partial depolymerisation
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
- C08K5/00—Use of organic ingredients
- C08K5/04—Oxygen-containing compounds
- C08K5/14—Peroxides
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
- C08L23/00—Compositions of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Compositions of derivatives of such polymers
- C08L23/26—Compositions of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Compositions of derivatives of such polymers modified by chemical after-treatment
- C08L23/30—Compositions of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Compositions of derivatives of such polymers modified by chemical after-treatment by oxidation
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
- C08F2810/00—Chemical modification of a polymer
- C08F2810/10—Chemical modification of a polymer including a reactive processing step which leads, inter alia, to morphological and/or rheological modifications, e.g. visbreaking
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
- C08J2323/00—Characterised by the use of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Derivatives of such polymers
- C08J2323/02—Characterised by the use of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Derivatives of such polymers not modified by chemical after treatment
- C08J2323/10—Homopolymers or copolymers of propene
- C08J2323/12—Polypropene
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
- C08J2423/00—Characterised by the use of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Derivatives of such polymers
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
- C08L23/00—Compositions of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Compositions of derivatives of such polymers
- C08L23/02—Compositions of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Compositions of derivatives of such polymers not modified by chemical after-treatment
- C08L23/10—Homopolymers or copolymers of propene
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- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Health & Medical Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Medicinal Chemistry (AREA)
- Polymers & Plastics (AREA)
- General Chemical & Material Sciences (AREA)
- Addition Polymer Or Copolymer, Post-Treatments, Or Chemical Modifications (AREA)
- Processes Of Treating Macromolecular Substances (AREA)
- Compositions Of Macromolecular Compounds (AREA)
- Processing And Handling Of Plastics And Other Materials For Molding In General (AREA)
- Artificial Filaments (AREA)
- Biological Depolymerization Polymers (AREA)
- Extrusion Moulding Of Plastics Or The Like (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE
Thermoplastic polypropylene polymers of improved processability obtained by initial partial degradation of high molecular weight polymers using a chemical prodegradant present in excess of the amount that reacts during pelletization. After pelletizing, the polymer can be handled and shipped without difficulty. When remelted by extruding or the like, the additional prodegradant in the pellets reacts further reducing the molecular weight as well as the molecular weight distribution of the polymer to a point where high capacity production of quality fibers and extruded products can be obtained.
The prodegradant is preferably of the type that predictably and controllably affects the polymer molecular properties without being significantly affected by minor fluctuations in the polymer producer's or processor's manufacturing steps.
Specific preferred embodiments include 2,5-dimethyl - 2,5 bis-(t-butylperoxy) hexyne-3 or 3,6,6,9,9-pentamethyl-3-(ethyl acetate)-1,2,4,5-textraoxy cyclononane as the prodegradant added in an amount providing an amount of unreacted pro-degradant after pelletizing of about 0.01 to 0.40 percent based on the weight of polymer. The present invention reduces the safety hazards attendant handling free radical prodegradants by the polymer processor and avoids the need for multiple addition of prodegradants while still producing a material that can be processed easily by the polymer producer and processor.
Thermoplastic polypropylene polymers of improved processability obtained by initial partial degradation of high molecular weight polymers using a chemical prodegradant present in excess of the amount that reacts during pelletization. After pelletizing, the polymer can be handled and shipped without difficulty. When remelted by extruding or the like, the additional prodegradant in the pellets reacts further reducing the molecular weight as well as the molecular weight distribution of the polymer to a point where high capacity production of quality fibers and extruded products can be obtained.
The prodegradant is preferably of the type that predictably and controllably affects the polymer molecular properties without being significantly affected by minor fluctuations in the polymer producer's or processor's manufacturing steps.
Specific preferred embodiments include 2,5-dimethyl - 2,5 bis-(t-butylperoxy) hexyne-3 or 3,6,6,9,9-pentamethyl-3-(ethyl acetate)-1,2,4,5-textraoxy cyclononane as the prodegradant added in an amount providing an amount of unreacted pro-degradant after pelletizing of about 0.01 to 0.40 percent based on the weight of polymer. The present invention reduces the safety hazards attendant handling free radical prodegradants by the polymer processor and avoids the need for multiple addition of prodegradants while still producing a material that can be processed easily by the polymer producer and processor.
Description
BACKGROUND OF THE l:~ENTIO~
. . _ . . . _ _ _ .
Field of the Invention This invention relates to polypropylene polymer pellets having improved processing characteristics for spinning, extruding and the like, as well as methods for obtaining them, A good processing polypropylene polymer for fiber or film form~tion desirably has the following attributes:
1) the ability to be attenuated. when molten without breaking - this allows high through-put production o fine filaments and thin films which have high s~rength relative to unattenuated products; and
. . _ . . . _ _ _ .
Field of the Invention This invention relates to polypropylene polymer pellets having improved processing characteristics for spinning, extruding and the like, as well as methods for obtaining them, A good processing polypropylene polymer for fiber or film form~tion desirably has the following attributes:
1) the ability to be attenuated. when molten without breaking - this allows high through-put production o fine filaments and thin films which have high s~rength relative to unattenuated products; and
2) the ability to be pumped throu~h pipin~
and capillaries and/or be attenuated as a fiber or film requiri~g a minimum of energy - this implies lower ~hear and extensional viscosities ~or ~he polymer melt It has been demonstrated that the ~irst attribute ., . i~' .
~2~
(high attenuabili-ty) can be attained with a propylene polymer having a narrow molecular weight distribution (defined as the polymer weight average mo]ecular weight divided by the polymer number average molecular weight). The second attribute (low shear and extensional viscosities3 is attained with a lower weight average molecular weight polymer.
Zeigler-Natta catalysts presently used in the commerical production of polypropylene produce polymers having too broad a molecular weight dis-tribution coming out o~ the polymerization reactor for production of fine fibers or thin films. Thus, low weight average molecular weight polymer out of such a reactor would have the desired low vis-cosity for processing, but would not be attenuable to the desired extent. Polypropylene suppliers have, therefore, found it necessary to make a very high weight average molecular weight polymer followed by a random molecular scission step (thermal or chemical degradation) which inherently narrows the molecular weight distribution while at the same time reduces the weight average molecular weight to the d~sired level.
Polypropylene is degraded chemically by addition of compounds that decompose forming free radicals.
Chemical stabilizers added to polypropylene to .~
enhance end-use stability may interfere with free radical generators.
However, it has been found that some free radical generator types of chemicals, such as the specific types of organic peroxides described in British Patent 1,442,681 for example, are minimally a~rected by commonly used stabilizers and are, thus, pre~erred prodegradants.
The degree to which the polymer can be degraded is limited, however, by the inability o the pol~mer producer to form pellets from very low viscosity polymers. Therefore, the poLypropylene processor manufacturing films a~d ~ibers faces the problem of having to use a polypropylene not optimally suited for th~se applications. Thus, a need has been demonstrated for a polymer having high viscosity properties fo~ pelletizing purposes and low viscosity properties for end use processing purposes.
Descri~tion of the Prior ~rt Low viscosity polypropylene polymer~ desirable to processors cannot presently be pelletized commer-cially by polymer producers without producing an excess of "stringers" (pellets with long tails) that tend to plug producers' and processors' equip-ment.
It has been suggested that the polymer viscosity ~2~ 6 could be increased for pelletizing by running the pelletizer at a temperature just above the poly-propylene polymer melting point to improve pellet cut. This can be done only at a low throughput to reduce the heat generated by shear forces in the pelletizing equipmen~ and/or by cooling the molten polymer - both adding considerably to the process cost and complexity.
It has also been suggested that the end use processor add additional chemical prodegradant to the polypropylene pellets to reduce the polymer viscosity to the desired level prior to fiber or film formation. Elowever, there are several dis-advantages to this approach;
1) the peroxide prodegradants are fire/
explosion hazards and require special handling procedures and equipment;
2) to be most effective, the peroxide must be uniformly dispersed within the polymer before it decomposes and reacts - other-wise a polymer with variable viscosity may result with an even broader molecular weight distribution than the original polymer. The polymer producer, having access to specialized equipment and the fine reactor flakes rather than pellets;
~l2~ 6 is in a much better position to achieve this uniform distribution;
and capillaries and/or be attenuated as a fiber or film requiri~g a minimum of energy - this implies lower ~hear and extensional viscosities ~or ~he polymer melt It has been demonstrated that the ~irst attribute ., . i~' .
~2~
(high attenuabili-ty) can be attained with a propylene polymer having a narrow molecular weight distribution (defined as the polymer weight average mo]ecular weight divided by the polymer number average molecular weight). The second attribute (low shear and extensional viscosities3 is attained with a lower weight average molecular weight polymer.
Zeigler-Natta catalysts presently used in the commerical production of polypropylene produce polymers having too broad a molecular weight dis-tribution coming out o~ the polymerization reactor for production of fine fibers or thin films. Thus, low weight average molecular weight polymer out of such a reactor would have the desired low vis-cosity for processing, but would not be attenuable to the desired extent. Polypropylene suppliers have, therefore, found it necessary to make a very high weight average molecular weight polymer followed by a random molecular scission step (thermal or chemical degradation) which inherently narrows the molecular weight distribution while at the same time reduces the weight average molecular weight to the d~sired level.
Polypropylene is degraded chemically by addition of compounds that decompose forming free radicals.
Chemical stabilizers added to polypropylene to .~
enhance end-use stability may interfere with free radical generators.
However, it has been found that some free radical generator types of chemicals, such as the specific types of organic peroxides described in British Patent 1,442,681 for example, are minimally a~rected by commonly used stabilizers and are, thus, pre~erred prodegradants.
The degree to which the polymer can be degraded is limited, however, by the inability o the pol~mer producer to form pellets from very low viscosity polymers. Therefore, the poLypropylene processor manufacturing films a~d ~ibers faces the problem of having to use a polypropylene not optimally suited for th~se applications. Thus, a need has been demonstrated for a polymer having high viscosity properties fo~ pelletizing purposes and low viscosity properties for end use processing purposes.
Descri~tion of the Prior ~rt Low viscosity polypropylene polymer~ desirable to processors cannot presently be pelletized commer-cially by polymer producers without producing an excess of "stringers" (pellets with long tails) that tend to plug producers' and processors' equip-ment.
It has been suggested that the polymer viscosity ~2~ 6 could be increased for pelletizing by running the pelletizer at a temperature just above the poly-propylene polymer melting point to improve pellet cut. This can be done only at a low throughput to reduce the heat generated by shear forces in the pelletizing equipmen~ and/or by cooling the molten polymer - both adding considerably to the process cost and complexity.
It has also been suggested that the end use processor add additional chemical prodegradant to the polypropylene pellets to reduce the polymer viscosity to the desired level prior to fiber or film formation. Elowever, there are several dis-advantages to this approach;
1) the peroxide prodegradants are fire/
explosion hazards and require special handling procedures and equipment;
2) to be most effective, the peroxide must be uniformly dispersed within the polymer before it decomposes and reacts - other-wise a polymer with variable viscosity may result with an even broader molecular weight distribution than the original polymer. The polymer producer, having access to specialized equipment and the fine reactor flakes rather than pellets;
~l2~ 6 is in a much better position to achieve this uniform distribution;
3) the processor's equipment may be damaged by a variable viscosity polymer;
4) the peroxide is more efficient as a pro-degradant if well dispersed before reacting;
and
and
5) the peroxide added to or on the pellets rather then within them acts as a lubri-cant in extruder ~eed sections reducing throughput for a given rpm.
The processor may also reduce the molecular weight by using very high temperatures to thermally degrade the polypropylene. However, these very high temperatures lead to:
1) reduced equipmen~ lie 2) throughput limitations because of quenching restraints 3) excessive energy consumption 4) hazardous operating environments; and 5) additive probLems~
The additive problems include:
1) excessive additive degradation, necessit~ting that more additive be added to the polymer than is required in the final product;
2) limited range of u~eable additives, requiring that more expensive or non-optimum additives be used; and 3) polymer piping, capillaries, dies, and the like plugging from the degradation products.
Additional information may be obtained by reference to prior patents. sritish Patent 1,442,681 to Chemie Linz describes a process for the préparation of polypropylene including degradation with peroxide prodegradants producing a narrow molecular weight distribution polypropylene polymer.
U.S. Patent 3~887,534 to Baba et al describes the use of aliphatic peroxides as prodegradants for polypropylene and discusses problems related thereto but suggests that unreacted prodegradant is to be avoided. U.S. Patent 3,144,436 to Greene et al describes a process for degrading steroregular polymers including the use of free radical initiators.
In one embodiment a two-step method is described wherein there is controlled injection of the pro-degradant into the me]t zone of the extruder. U.S.
Patent 3,849,241 to Buntin et al and U. S. Patent 3,978,185 also to Buntin et al describe meltblowing processes that are improved through controlled de-gradation of the polymers. U~S. Patent 3,755,527 to Keller et al similarly describes advantages of g~.''' 3~2P~
polymer degradation.
SUMMAR~
The present invention encompasses, 1) a step-wise method of degrading polypropylene, initially producing a polymer that is readily formed into pellets that when heated undergo fuxther degradation producing a low viscosity polymer that can be conveniently processed into high quality films and fibers; and 2) prodegradant containing polypropy-lene polymer in the form of pellets and the likeresulting from this method.
The present invention results from the dis-covery that when certain free radical generating chemicals that act as polypropylene prodegradants are added to the polymer and the pelleti~ing equipment operated in a specified manner, a portion of the chemical ~urvive the pelletizing process~
After extrusion to form pellets the reaction is interrupted and the remainder of the prodegradant will then react upon re-extrusion producing a polymer that processes well and produces ~ilms and fibers with excellent properties. The exact remaining percentage of prodegradant after pelletizing by the producer will vary depending upon pelletizing temperature, prodegradant residence time at this temperature, and type of prodegradant, but will liL7~i preferably be more than half and up to 90~ of that originally added. Ideally, for pelletizing, no degradation takes place, but, as a practical matter, some prode~radant will initially react during pellet-izing. The small amount reacting initially, as low as about 10%, only minimally reduces the polymer viscosity at the pelletizer, permitting well formed, free flowing pellets to be made. ~fter pelletizing, residual prodegradant in an amount of at least 0.01 percent based on the weight of polymer is necessary for acceptable results to be obtained.
Thus, the advantages of a two-step degradation addition method described above in connection with the prior art are retained, but the disadvantages are substantially eliminated.
BRIEF DESCRIPTION OF THE DRAWINGS
FIGURE 1 is a graph showing the relationship between reaction time and viscosity at extrusion temperatures for polypropylene with two prodegradant embodiments of the invention; and FIG. 2 is a graph of exiting polymer viscosity versus percent prodegradant added as a liquid and as a concentrate.
DESCRIPTION OF TIJE PRBFERRED EMBODIMENTS
While the invention will be described in connection with preferred embo~iments, it will be understood that it is not intended to limit the invention to those embodiments. On the contrary, it is intended to cover all alternatives, modifi-g cations, and equivalents as may be included within the spirit and scope of the invention as defined by the appended claims.
The invention is applicable to the production and processing of polypropylene. It is also applicable to the processing of waste polypropy-lene material to permit reuse in film and Eiber formation. 0f course, as will be apparent to one skilled in the art, OptilllUIII operating conditions and concentrations will vary depending upon the properties of the po]ymer being used and the ultimate properties desired by the processor.
As produced, polypropylene generally has a high weight average molecular weight in the range of from about 250,000 to 500,000 and a molecular weiqht dis-tribution of about 10 to 15. For high speed spinning and fiber forming, the weight average molecular weight distribution is preferably about 2.5 to 4.5.
However, when the molecular weight is reduced below ~out 130,000 , the polypropylene resin cannot be easily commerically processed into pellats. The low viscosity polymer instead produces poorly formed pellets which are difficult to transport and handle.
Therefore, manufacturers prefer that the de~radation of polypropylene prior to delivery be limited to ~ 10 --~J
produce a molecular weight not less than about 160,000. Many prodegradants are used to achieve this degree of degradation in pelletizing equipment, and most of them totally react under these conditions.
Peroxide prodegradants decompose at different rates depending on temperature and environment. The rates of decomposition are defined in terms of half-life.
In accordance with the invention a free radical source prodegradant having a half-life in poly-propylene in excess of one-half minute at ~75 F.
is added to a high molecular weight polypropylene reactor flake polymer in an amount sufficient to produce the final polymer properties desired by the polymer processor. If it is desired to use a pro-degradant with a shorter half-life or allow a greater amount of prodegradant to make it through the pelletization step unreacted, it is also possible to inject the prodegradant into the molten polymer stream. As the prodegradant rnust be dispersed U~
formly to be most effective, the injection should be followed by a mixing step. In general, the prodegradant should not interfere with or be interfered with by commonly used polypropylene stabilizers and should effectively produce free radicals that upon decomposition initiate poly-propylene degradation. The prodegradant should have a short enough halE-liEe a-t the polymer processor's re-extrusion temperatures, however, so as to be essentially entirely reacted before exi-ting the extruder. Preferably they have a nalf--life in -the polypropylene of less than 9 seconds at 550~F. so tha-t at least 99~ of the prodegradant in the pellets reacts before 1 minute of extruder residence time at this temperature elapses. Such prodegradants include, by way of example and not limitation, the following:
2,5-dimethyl-2,5-bis(tert-butyl-peroxy)hexyne-3, q-methyl-4-tert-butyl-peroxy-2-pentanone (e.g. Lupersol 130 and Lupersol 120 available from Lucidol Division, Penwalt Corporation), 3,6,6,9,9-pentamethyl~3-(ethyl-acetate)-1,2,4,5-tetraoxycyclononane, (USP-138 from Witco Chemical Corporation), 2,5-dimethyl-2,5-bis(tert-butyl-peroxy)hexane (e.g. Lupersol 101) and ~,~'-bis-(tert-butyl-peroxy)diisopropylbenzene (Vulcup R Erom * *
Hercules, Inc.). Of these Witco USP-138 and Lupersol 130 are highly preferred. Preferred concentrations of the free radical source prodegradants are in the range of Erom about 0.01 to 0.4 percent based on the weight of the polymers. Preferably the pelletizer is operated to retain at least 75~ of the added prodegradant in the pellets. When subjectea to extruding temperatures by the pol~-mer user, the degradation of the polymer will .~
~~~i *trade mar~
J ~ l1 ~p~
resume and proceed to the extent desired, essentially completely reacting in the re-extrusion processO
Generally such extruder temperatures are in the range of from about ~60 F. to 550 F. Alternatively, these conditions may be obtained for degradation in the extruder die assembly.
In the following examples melt indices were determined using melt indexer (ASTM 123~) operated at 177 F. with a 2160 g. weight. Samples were allowed to heat ~o equilibrium for 5 minutes prior to testing. The melt index is equivalent to the grams exiting at 0.0825 inch diameter capillary in a period of 10 minutes.
Examples Example 1 A polypropylene reactor flake was obtained that had a melt index of less than one. 0.275 weight percent Lupersol 130 was added to -the flake and a homogeneous blend made. This blend was pelletized ~0 in pelletizing equipment operated at 375 F. and the residence time was about 2 minutes. Calculations show about 22~ of the peroxide had reacted. The pellets were tested and found to have a melt index of about 5S. Approximately 10% of the prodegradant in the pellets reacted in the melt indexer so that actual melt index may be considered to be in the * trade mark X~'' ~2~
40-45 range for the pellets. This polymer was easily pelletized and gave polymer pellets equivalent to normal commercial pellets.
These pellets were then re-extruded at 460 F.
with an extruder residence time of about 3 minutes.
The extrudate was then tested and found to have a melt inde~ of about 550. To veriy that the 460 F. extrusion step did not appreciably affect the melt index, the extrudate was re-extruded and the melt index increased from 550 .o 580. Thus, about 95~ of the melt index increase ~as due to the pro-dsgradant in the pellets and about 5~ due to the action of the extruder.
Example 2 .
The same flake and equipment was used as in Example 1 except that 0.3~ Lupersol 130 was added to tne flake. The pellets were found to have a melt index of 45-50. Upon re-extrusion, the extrudate was found to have a melt index of about 660. As in Example 1, the pellet cut was commercially acceptable.
Example 3 Witco Chemical USP-138 was applied to the flake at a concentration of 0.35 weight percent.
The blend was extruded at 375 F. ~or an extruder residen~e time of about 2 minutes. The melt index . - 14 -* trade mark of the extruded sample was found to be about 15.
The sample was re-extruded at 485 F. with a 3 minute residence time and the melt index was found to be 215. The flake without peroxide added but processed in the above manner had a melt index of 1.7.
Example 4 2% Lupersol*130 was blended with commercially availa~le polypropylene pellets identified as Her-cules PC-973. This blend was then extruded at 170 C. with a one minute residence time. Cal-culations show 98~ ~f the peroxide remained un- -reacted in the extrudate. Various percentages of the peroxide concentrate extrudate were then blended with polypropylene pellets. A calculated equivalent amount of pure peroxide was added to other pellets.
The "concentrate"/polypropylene blend and liquid peroxide/polypropylene blend was extruded through a ~rabender extruder at 465 F. with a seven minute residence time. The vlscosities exiting the extruder die tip were determined and are shown in Figure 2.
They can be seen to be equivalent.
Thus, the invention includes prodegxadant concentrates which can be added to non-prodegradant containing pellets to gain desired results. Concen-trations of up to 5% by weight prodegradant can be * trade mark ~' .
formed with ease, and higher concentrations are possible.
While it is not desired to limit the invention to any particular theory, the significance of certain prodegradant characteri.stics may be postulated.
From half-life determinations it can be shown that half-life reaction rate coefficients, k, approximately follow an Arrhenius relationship to give:
ln k = -19,700 + 40.4 for Lupersol 130 T
ln k= -19,700 + 41.6 for Lupersol 101 T
Where k = half-life reaction rate coefficient in . -1, and T = temperature, K
polypropylene, m1n.
Having determined k, the following equation may be used to find the amount of unreacted pro-degradant after a given time~
CA = e~kt CAo where CA = concentration of unreacted prodegradant;
A = initial prodegradant concentration; and t = reaction time, rnin.For example, after one rninute at 410 F. t483 t 50% of the original Lupersol 130 would be unrea~ted as compared to only 10% of Lupersol 101 under the same conditions.
In addition, it can be shown that * trade mark , 7~.
the polymer viscosity exiting a piece of equip-ment can be predicted by the following equation:
1 = 1 + KCR
Where: ~ = polymer viscosity exiting the equipment after chemical degradation;
~ = viscosity the polymer would have had exiting without chemical degradation;
K = chemical degradation efficiency co-efficient; and CR = amount of prodegradant reacted upon exiting.
Since CR - CA - CA~ combining the above equations gives the following equation: !
1 = 1 ~ K CA (1 - e~kt) 1~ ~1 Thus, for a constant (KCA) the ultimate polymer viscosity will be the same after a long reaction time regardless of prodegradant used. However, the relationship between viscosity and time will depend upon the half-life reaction rate coefficient, k. For example, FIG. 1 is a graph of exiting polypropylene polymer viscosity versus time based on KCA - 0.005 poise~l (a typical value eOg. for Lupersol 130 or 101) and an initial polymer vis-cosity of 10,000 poise with the pelletizing~ex-trusion processes carried out at 395 F. It dem-. - 17 -* trade mark ~ .
~L2~ 76 onstrates that the "pelletizing" viscosity of the Lupersol 130 sample is about twice that of the Lupersol 101 sample at a normal pelletizing time range of 1 to 3 minutes although the ultimate viscosities ~ould be about the same.
For a prodegradant with a short half-life, the viscosity of the polypropylene upon exiting a pelletizer at 395 F. after 1 minute residence time is only 67~ of that i~ Lupersol 101 was used and only 30~ of that if Lupersol 130 was used, Thus, the latter is preferred, although the others may be used.
Although, in the ~ase of Lupersol 130~ about 50% o~ the prode~radant may remain after pelletizing, because the initial addition level is quite low, there is little or no danger in handling the polymer.
After re-extrusion there will be essentially no prodegradant remaining since typical proces~ing conditions are at léast 460 F. at which the Lupersol 130 half-life coefficient is over 6 min.~l. With an equipment residence time of only 2-1/2 minutes, for example, only 0.000017~ of the peroxide in the pellets would remain in the extrudate. For example, if the polypropylene pellets had 0.2~ Lupersol 130 as received from the producer, the processor's extrusion equipment was operated at 460 F., and the * trade mark ~' '7~i extruder residence time was 2-1/2 minutes, the Lupersol 130 concentration in the polymer exiting the extruder would be less than 1 part per billion.
Thus it is apparent that there has been pro-vided in accordance with the invention, a poly~er composition maintaining easy pelletization for polymer producers while significantly improving the processor's ability to use it and a method for manufacturi~g the material that fully satisfy the objects, aims and advantages set forth above.
t~hile the invention has been described in connection with specific embodiments thereo~, it is evident that many alternatives, modifications, and variations will be apparent to those skilled in the art in light o~ the foregoing description. Accordingly, it is intended to embrace all such alternatives, modifi-cations and variations as fall wi.hin the spirit and broad scope of the appended claims.
~ 19 -* trade mark ~;
"7
The processor may also reduce the molecular weight by using very high temperatures to thermally degrade the polypropylene. However, these very high temperatures lead to:
1) reduced equipmen~ lie 2) throughput limitations because of quenching restraints 3) excessive energy consumption 4) hazardous operating environments; and 5) additive probLems~
The additive problems include:
1) excessive additive degradation, necessit~ting that more additive be added to the polymer than is required in the final product;
2) limited range of u~eable additives, requiring that more expensive or non-optimum additives be used; and 3) polymer piping, capillaries, dies, and the like plugging from the degradation products.
Additional information may be obtained by reference to prior patents. sritish Patent 1,442,681 to Chemie Linz describes a process for the préparation of polypropylene including degradation with peroxide prodegradants producing a narrow molecular weight distribution polypropylene polymer.
U.S. Patent 3~887,534 to Baba et al describes the use of aliphatic peroxides as prodegradants for polypropylene and discusses problems related thereto but suggests that unreacted prodegradant is to be avoided. U.S. Patent 3,144,436 to Greene et al describes a process for degrading steroregular polymers including the use of free radical initiators.
In one embodiment a two-step method is described wherein there is controlled injection of the pro-degradant into the me]t zone of the extruder. U.S.
Patent 3,849,241 to Buntin et al and U. S. Patent 3,978,185 also to Buntin et al describe meltblowing processes that are improved through controlled de-gradation of the polymers. U~S. Patent 3,755,527 to Keller et al similarly describes advantages of g~.''' 3~2P~
polymer degradation.
SUMMAR~
The present invention encompasses, 1) a step-wise method of degrading polypropylene, initially producing a polymer that is readily formed into pellets that when heated undergo fuxther degradation producing a low viscosity polymer that can be conveniently processed into high quality films and fibers; and 2) prodegradant containing polypropy-lene polymer in the form of pellets and the likeresulting from this method.
The present invention results from the dis-covery that when certain free radical generating chemicals that act as polypropylene prodegradants are added to the polymer and the pelleti~ing equipment operated in a specified manner, a portion of the chemical ~urvive the pelletizing process~
After extrusion to form pellets the reaction is interrupted and the remainder of the prodegradant will then react upon re-extrusion producing a polymer that processes well and produces ~ilms and fibers with excellent properties. The exact remaining percentage of prodegradant after pelletizing by the producer will vary depending upon pelletizing temperature, prodegradant residence time at this temperature, and type of prodegradant, but will liL7~i preferably be more than half and up to 90~ of that originally added. Ideally, for pelletizing, no degradation takes place, but, as a practical matter, some prode~radant will initially react during pellet-izing. The small amount reacting initially, as low as about 10%, only minimally reduces the polymer viscosity at the pelletizer, permitting well formed, free flowing pellets to be made. ~fter pelletizing, residual prodegradant in an amount of at least 0.01 percent based on the weight of polymer is necessary for acceptable results to be obtained.
Thus, the advantages of a two-step degradation addition method described above in connection with the prior art are retained, but the disadvantages are substantially eliminated.
BRIEF DESCRIPTION OF THE DRAWINGS
FIGURE 1 is a graph showing the relationship between reaction time and viscosity at extrusion temperatures for polypropylene with two prodegradant embodiments of the invention; and FIG. 2 is a graph of exiting polymer viscosity versus percent prodegradant added as a liquid and as a concentrate.
DESCRIPTION OF TIJE PRBFERRED EMBODIMENTS
While the invention will be described in connection with preferred embo~iments, it will be understood that it is not intended to limit the invention to those embodiments. On the contrary, it is intended to cover all alternatives, modifi-g cations, and equivalents as may be included within the spirit and scope of the invention as defined by the appended claims.
The invention is applicable to the production and processing of polypropylene. It is also applicable to the processing of waste polypropy-lene material to permit reuse in film and Eiber formation. 0f course, as will be apparent to one skilled in the art, OptilllUIII operating conditions and concentrations will vary depending upon the properties of the po]ymer being used and the ultimate properties desired by the processor.
As produced, polypropylene generally has a high weight average molecular weight in the range of from about 250,000 to 500,000 and a molecular weiqht dis-tribution of about 10 to 15. For high speed spinning and fiber forming, the weight average molecular weight distribution is preferably about 2.5 to 4.5.
However, when the molecular weight is reduced below ~out 130,000 , the polypropylene resin cannot be easily commerically processed into pellats. The low viscosity polymer instead produces poorly formed pellets which are difficult to transport and handle.
Therefore, manufacturers prefer that the de~radation of polypropylene prior to delivery be limited to ~ 10 --~J
produce a molecular weight not less than about 160,000. Many prodegradants are used to achieve this degree of degradation in pelletizing equipment, and most of them totally react under these conditions.
Peroxide prodegradants decompose at different rates depending on temperature and environment. The rates of decomposition are defined in terms of half-life.
In accordance with the invention a free radical source prodegradant having a half-life in poly-propylene in excess of one-half minute at ~75 F.
is added to a high molecular weight polypropylene reactor flake polymer in an amount sufficient to produce the final polymer properties desired by the polymer processor. If it is desired to use a pro-degradant with a shorter half-life or allow a greater amount of prodegradant to make it through the pelletization step unreacted, it is also possible to inject the prodegradant into the molten polymer stream. As the prodegradant rnust be dispersed U~
formly to be most effective, the injection should be followed by a mixing step. In general, the prodegradant should not interfere with or be interfered with by commonly used polypropylene stabilizers and should effectively produce free radicals that upon decomposition initiate poly-propylene degradation. The prodegradant should have a short enough halE-liEe a-t the polymer processor's re-extrusion temperatures, however, so as to be essentially entirely reacted before exi-ting the extruder. Preferably they have a nalf--life in -the polypropylene of less than 9 seconds at 550~F. so tha-t at least 99~ of the prodegradant in the pellets reacts before 1 minute of extruder residence time at this temperature elapses. Such prodegradants include, by way of example and not limitation, the following:
2,5-dimethyl-2,5-bis(tert-butyl-peroxy)hexyne-3, q-methyl-4-tert-butyl-peroxy-2-pentanone (e.g. Lupersol 130 and Lupersol 120 available from Lucidol Division, Penwalt Corporation), 3,6,6,9,9-pentamethyl~3-(ethyl-acetate)-1,2,4,5-tetraoxycyclononane, (USP-138 from Witco Chemical Corporation), 2,5-dimethyl-2,5-bis(tert-butyl-peroxy)hexane (e.g. Lupersol 101) and ~,~'-bis-(tert-butyl-peroxy)diisopropylbenzene (Vulcup R Erom * *
Hercules, Inc.). Of these Witco USP-138 and Lupersol 130 are highly preferred. Preferred concentrations of the free radical source prodegradants are in the range of Erom about 0.01 to 0.4 percent based on the weight of the polymers. Preferably the pelletizer is operated to retain at least 75~ of the added prodegradant in the pellets. When subjectea to extruding temperatures by the pol~-mer user, the degradation of the polymer will .~
~~~i *trade mar~
J ~ l1 ~p~
resume and proceed to the extent desired, essentially completely reacting in the re-extrusion processO
Generally such extruder temperatures are in the range of from about ~60 F. to 550 F. Alternatively, these conditions may be obtained for degradation in the extruder die assembly.
In the following examples melt indices were determined using melt indexer (ASTM 123~) operated at 177 F. with a 2160 g. weight. Samples were allowed to heat ~o equilibrium for 5 minutes prior to testing. The melt index is equivalent to the grams exiting at 0.0825 inch diameter capillary in a period of 10 minutes.
Examples Example 1 A polypropylene reactor flake was obtained that had a melt index of less than one. 0.275 weight percent Lupersol 130 was added to -the flake and a homogeneous blend made. This blend was pelletized ~0 in pelletizing equipment operated at 375 F. and the residence time was about 2 minutes. Calculations show about 22~ of the peroxide had reacted. The pellets were tested and found to have a melt index of about 5S. Approximately 10% of the prodegradant in the pellets reacted in the melt indexer so that actual melt index may be considered to be in the * trade mark X~'' ~2~
40-45 range for the pellets. This polymer was easily pelletized and gave polymer pellets equivalent to normal commercial pellets.
These pellets were then re-extruded at 460 F.
with an extruder residence time of about 3 minutes.
The extrudate was then tested and found to have a melt inde~ of about 550. To veriy that the 460 F. extrusion step did not appreciably affect the melt index, the extrudate was re-extruded and the melt index increased from 550 .o 580. Thus, about 95~ of the melt index increase ~as due to the pro-dsgradant in the pellets and about 5~ due to the action of the extruder.
Example 2 .
The same flake and equipment was used as in Example 1 except that 0.3~ Lupersol 130 was added to tne flake. The pellets were found to have a melt index of 45-50. Upon re-extrusion, the extrudate was found to have a melt index of about 660. As in Example 1, the pellet cut was commercially acceptable.
Example 3 Witco Chemical USP-138 was applied to the flake at a concentration of 0.35 weight percent.
The blend was extruded at 375 F. ~or an extruder residen~e time of about 2 minutes. The melt index . - 14 -* trade mark of the extruded sample was found to be about 15.
The sample was re-extruded at 485 F. with a 3 minute residence time and the melt index was found to be 215. The flake without peroxide added but processed in the above manner had a melt index of 1.7.
Example 4 2% Lupersol*130 was blended with commercially availa~le polypropylene pellets identified as Her-cules PC-973. This blend was then extruded at 170 C. with a one minute residence time. Cal-culations show 98~ ~f the peroxide remained un- -reacted in the extrudate. Various percentages of the peroxide concentrate extrudate were then blended with polypropylene pellets. A calculated equivalent amount of pure peroxide was added to other pellets.
The "concentrate"/polypropylene blend and liquid peroxide/polypropylene blend was extruded through a ~rabender extruder at 465 F. with a seven minute residence time. The vlscosities exiting the extruder die tip were determined and are shown in Figure 2.
They can be seen to be equivalent.
Thus, the invention includes prodegxadant concentrates which can be added to non-prodegradant containing pellets to gain desired results. Concen-trations of up to 5% by weight prodegradant can be * trade mark ~' .
formed with ease, and higher concentrations are possible.
While it is not desired to limit the invention to any particular theory, the significance of certain prodegradant characteri.stics may be postulated.
From half-life determinations it can be shown that half-life reaction rate coefficients, k, approximately follow an Arrhenius relationship to give:
ln k = -19,700 + 40.4 for Lupersol 130 T
ln k= -19,700 + 41.6 for Lupersol 101 T
Where k = half-life reaction rate coefficient in . -1, and T = temperature, K
polypropylene, m1n.
Having determined k, the following equation may be used to find the amount of unreacted pro-degradant after a given time~
CA = e~kt CAo where CA = concentration of unreacted prodegradant;
A = initial prodegradant concentration; and t = reaction time, rnin.For example, after one rninute at 410 F. t483 t 50% of the original Lupersol 130 would be unrea~ted as compared to only 10% of Lupersol 101 under the same conditions.
In addition, it can be shown that * trade mark , 7~.
the polymer viscosity exiting a piece of equip-ment can be predicted by the following equation:
1 = 1 + KCR
Where: ~ = polymer viscosity exiting the equipment after chemical degradation;
~ = viscosity the polymer would have had exiting without chemical degradation;
K = chemical degradation efficiency co-efficient; and CR = amount of prodegradant reacted upon exiting.
Since CR - CA - CA~ combining the above equations gives the following equation: !
1 = 1 ~ K CA (1 - e~kt) 1~ ~1 Thus, for a constant (KCA) the ultimate polymer viscosity will be the same after a long reaction time regardless of prodegradant used. However, the relationship between viscosity and time will depend upon the half-life reaction rate coefficient, k. For example, FIG. 1 is a graph of exiting polypropylene polymer viscosity versus time based on KCA - 0.005 poise~l (a typical value eOg. for Lupersol 130 or 101) and an initial polymer vis-cosity of 10,000 poise with the pelletizing~ex-trusion processes carried out at 395 F. It dem-. - 17 -* trade mark ~ .
~L2~ 76 onstrates that the "pelletizing" viscosity of the Lupersol 130 sample is about twice that of the Lupersol 101 sample at a normal pelletizing time range of 1 to 3 minutes although the ultimate viscosities ~ould be about the same.
For a prodegradant with a short half-life, the viscosity of the polypropylene upon exiting a pelletizer at 395 F. after 1 minute residence time is only 67~ of that i~ Lupersol 101 was used and only 30~ of that if Lupersol 130 was used, Thus, the latter is preferred, although the others may be used.
Although, in the ~ase of Lupersol 130~ about 50% o~ the prode~radant may remain after pelletizing, because the initial addition level is quite low, there is little or no danger in handling the polymer.
After re-extrusion there will be essentially no prodegradant remaining since typical proces~ing conditions are at léast 460 F. at which the Lupersol 130 half-life coefficient is over 6 min.~l. With an equipment residence time of only 2-1/2 minutes, for example, only 0.000017~ of the peroxide in the pellets would remain in the extrudate. For example, if the polypropylene pellets had 0.2~ Lupersol 130 as received from the producer, the processor's extrusion equipment was operated at 460 F., and the * trade mark ~' '7~i extruder residence time was 2-1/2 minutes, the Lupersol 130 concentration in the polymer exiting the extruder would be less than 1 part per billion.
Thus it is apparent that there has been pro-vided in accordance with the invention, a poly~er composition maintaining easy pelletization for polymer producers while significantly improving the processor's ability to use it and a method for manufacturi~g the material that fully satisfy the objects, aims and advantages set forth above.
t~hile the invention has been described in connection with specific embodiments thereo~, it is evident that many alternatives, modifications, and variations will be apparent to those skilled in the art in light o~ the foregoing description. Accordingly, it is intended to embrace all such alternatives, modifi-cations and variations as fall wi.hin the spirit and broad scope of the appended claims.
~ 19 -* trade mark ~;
"7
Claims (10)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A method for producing polypropylene pellets having improved extrusion characteristics, comprising:
a) providing polypropylene having a high viscosity, a high weight average molecular weight and a broad molecular weight distribution;
b) adding to said polypropylene and uniformly dispersing therethrough a free radical generating prodegradant having a half-life in said polypropylene in excess of one-half minute at 375°F; and c) pelletizing the polymer product of step b) under conditions wherein greater than about 50 percent of that added and at least about 0.01 weight percent of said prodegradent remains available for further degradation after pelletizing.
a) providing polypropylene having a high viscosity, a high weight average molecular weight and a broad molecular weight distribution;
b) adding to said polypropylene and uniformly dispersing therethrough a free radical generating prodegradant having a half-life in said polypropylene in excess of one-half minute at 375°F; and c) pelletizing the polymer product of step b) under conditions wherein greater than about 50 percent of that added and at least about 0.01 weight percent of said prodegradent remains available for further degradation after pelletizing.
2. The method of claim 1, including the addi-tional step of extruding the pelletized polymer product of step c) under conditions causing the remaining pro-degradant to substantially completely react, to produce a low viscosity propylene polymer suitable for film and fiber forming.
3. The method of claim 1, wherein step a) said polypropylene has a weight average molecular weight in the range of from about 250,000 to 500,000 and a molecular weight distribution of about 10 to 15 prior to addition of said prodegradant.
4. The method of claim 1, wherein step b) said prodegradant is added in an amount of from about 0.01 to 0.4 weight percent of said polypropylene weight, and wherein step c) at least 75 percent of the added pro-degradant remains.
5. The method of claim 2, wherein the low viscosity propylene polymer product has a weight average molecular weight in the range of from about 60,000 to 130,000 with a molecular weight distribution of about 2.5 to 4.5 after said prodegradant has substantially completely reacted.
6. The method of claim 1, 3 or 4 wherein step b) said prodegradant is selected from the group consisting of: 2,5-dimethyl-2,5-bis(t-butylperoxy)hexyne-3, 4-methyl-4-t-butylperoxy-2-pentanone, 3,6,6,9,9-pentamethyl-3-(ethyl-acetate)-1,2,4,5-tetraoxycyclononane, 2,5-dimethyl-2,5-bis(t-butylperoxy)hexane and .alpha.,.alpha.'-bis(t-butylperoxy) diisopropylbenzene.
7. The method of claim 4, wherein step c) at least 90 percent of the added prodegradant remains.
3. Polypropylene pellets containing at least about 0.01 weight percent of an unreacted free radical generating prodegradant having a half-life in polypropylene in excess of one-half minute at 375°F, the pellets when extruded under conditions causing the unreacted prodegradant to substantially completely react forming a low viscosity propylene polymer suitable for film and fiber forming.
9. Polypropylene pellets of claim 9, wherein said prodegradant is selected from the group consisting of: 2,5-dimethyl-2,5-bis(t-butylperoxy)hexyne-3, 4-methyl-4-t-butylperoxy-2-pentanone, 3,6,6,9,9-pentamethyl-3-(ethyl- acetate)-1,2,4,5-tetraoxycyclononane, 2,5-dimethyl-2,5-bis(t-butylperoxy)hexane and .alpha.,.alpha.'-bis(t-butylperoxy) diisopropylbenzene.
10. A polypropylene pelleted concentrate blend of propylene polymer and from greater than 0.4 up to 5 weight percent of an unreacted free radical generating prodegradant having a half-life in polypropylene in excess of one-half minute at 375°F, that when added to the polypropylene de-fined in claim 1, step a) so that the concentration of said prodegradant in the total polypropylene composition is at least 0.4 weight percent will reduce the polymer viscosity to permit high capacity extrusion.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US27393881A | 1981-06-15 | 1981-06-15 | |
| US273,938 | 1981-06-15 |
Publications (1)
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|---|---|
| CA1210176A true CA1210176A (en) | 1986-08-19 |
Family
ID=23046062
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000404450A Expired CA1210176A (en) | 1981-06-15 | 1982-06-03 | Degradation of polypropylene for future improved processability |
Country Status (15)
| Country | Link |
|---|---|
| JP (2) | JPS5823804A (en) |
| KR (1) | KR860001115B1 (en) |
| AU (1) | AU554655B2 (en) |
| BE (1) | BE893522A (en) |
| BR (1) | BR8203490A (en) |
| CA (1) | CA1210176A (en) |
| DE (1) | DE3222498C2 (en) |
| FR (1) | FR2507607B1 (en) |
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| IT (1) | IT1157210B (en) |
| LU (1) | LU84200A1 (en) |
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| NL (1) | NL190931C (en) |
| PH (1) | PH19549A (en) |
| ZA (1) | ZA824064B (en) |
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|---|---|---|---|---|
| JPS6099108A (en) * | 1983-11-04 | 1985-06-03 | Tokuyama Soda Co Ltd | Preparation of molded article of polypropylene |
| US4766200A (en) * | 1984-06-01 | 1988-08-23 | The Hygenic Corporation | Process for improving the melt flow index of thermoplastic polymers |
| US4966952A (en) * | 1984-06-01 | 1990-10-30 | The Hygenic Corporation | Thermoplastic polymer composition comprising trans 1,4-polyisoprene |
| EP0227048A3 (en) * | 1985-12-24 | 1989-03-08 | Paul J. Albee, Jr. | Peroxide concentrate and polymer carrier |
| US4707524A (en) * | 1986-05-06 | 1987-11-17 | Aristech Chemical Corporation | Controlled-rheology polypropylene |
| US4882407A (en) * | 1986-12-23 | 1989-11-21 | The Hygenic Corporation | Thermoplastic endodontic composition having improved melt flow index |
| FR2613722B1 (en) * | 1987-04-07 | 1990-11-23 | Bp Chimie Sa | PROCESS FOR THE MANUFACTURE OF PROPYLENE HOMOPOLYMER OR COPOLYMER GRANULES |
| GB2206525B (en) * | 1987-07-08 | 1990-03-07 | Courtaulds Films & Packaging | Orientated polypropylene films |
| GB2206524B (en) * | 1987-07-08 | 1990-03-07 | Courtaulds Films & Packaging | Voided polypropylene films |
| FR2620079B1 (en) * | 1987-09-04 | 1990-01-19 | Arjomari Prioux | HIGH-MOULDABILITY REINFORCED THERMOPLASTIC SHEET |
| FR2627498B1 (en) * | 1988-02-19 | 1990-07-06 | Labofina Sa | POLYPROPYLENE PROCESSING PROCESS |
| US5264493A (en) * | 1988-02-19 | 1993-11-23 | Fina Research, S.A. | Process for the treatment of polypropylene |
| US5198506A (en) * | 1991-05-10 | 1993-03-30 | Phillips Petroleum Company | High organic peroxide content polypropylene |
| AT403581B (en) * | 1993-06-07 | 1998-03-25 | Danubia Petrochem Polymere | METHOD FOR PRODUCING NEW POLYPROPYLENE BY CHEMICAL DEGRADING |
| DE4321529A1 (en) * | 1993-06-29 | 1995-01-12 | Danubia Petrochem Deutschland | Novel polypropylenes obtainable by chemical degradation |
| US5814404A (en) * | 1994-06-03 | 1998-09-29 | Minnesota Mining And Manufacturing Company | Degradable multilayer melt blown microfibers |
| US5594074A (en) * | 1995-02-21 | 1997-01-14 | Shell Oil Company | Process for improving processability of ultra low melt viscosity polymer |
| US6423800B1 (en) * | 1999-05-26 | 2002-07-23 | Fina Technology, Inc. | Pelletized polyolefin having ultra-high melt flow and its articles of manufacture |
| GB0005629D0 (en) * | 2000-03-10 | 2000-05-03 | Clariant Int Ltd | Light stabilizer composition |
| DE102011110154A1 (en) * | 2011-08-12 | 2013-02-14 | Deutsche Institute Für Textil- Und Faserforschung Denkendorf | METHOD FOR THE PRODUCTION OF SURFACE-MODIFIED POLYOLEFIN YARNES, THE POLYOLEFINGARIN THEREFORE AVAILABLE AND THE USE THEREOF |
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| JPS4833023A (en) * | 1971-08-30 | 1973-05-07 | ||
| JPS5148196B2 (en) * | 1972-03-11 | 1976-12-18 | ||
| TR17756A (en) * | 1972-07-25 | 1976-07-01 | Oesterr Stickstoffwerke Ag | PROCEDURE FOR THE MANUFACTURING OF POLYPROPYLENE WITH MAHDUT MOLECUEL WEIGHT |
| JPS5635689B2 (en) * | 1973-03-13 | 1981-08-19 | ||
| US4087486A (en) * | 1975-05-15 | 1978-05-02 | Standard Oil Company (Indiana) | Polypropylene composition containing EPR |
| JPS6016974B2 (en) * | 1976-10-27 | 1985-04-30 | 古河電気工業株式会社 | Method for preparing polyolefin resin pellets or particles impregnated with organic peroxide |
| JPS55742A (en) * | 1978-06-20 | 1980-01-07 | Kazuo Saotome | Polymer composition composed of polypropylene having relatively low molecular weight |
| US4296022A (en) * | 1980-06-04 | 1981-10-20 | Chevron Research | Polypropylene blend compositions |
-
1982
- 1982-06-03 CA CA000404450A patent/CA1210176A/en not_active Expired
- 1982-06-09 ZA ZA824064A patent/ZA824064B/en unknown
- 1982-06-10 AU AU84767/82A patent/AU554655B2/en not_active Expired
- 1982-06-14 NL NL8202406A patent/NL190931C/en not_active IP Right Cessation
- 1982-06-14 MX MX193140A patent/MX167645B/en unknown
- 1982-06-14 PH PH27421A patent/PH19549A/en unknown
- 1982-06-14 BR BR8203490A patent/BR8203490A/en unknown
- 1982-06-15 JP JP57102925A patent/JPS5823804A/en active Granted
- 1982-06-15 FR FR8210435A patent/FR2507607B1/en not_active Expired
- 1982-06-15 DE DE3222498A patent/DE3222498C2/en not_active Expired - Lifetime
- 1982-06-15 BE BE0/208354A patent/BE893522A/en not_active IP Right Cessation
- 1982-06-15 KR KR8202669A patent/KR860001115B1/en active
- 1982-06-15 IT IT48643/82A patent/IT1157210B/en active
- 1982-06-15 LU LU84200A patent/LU84200A1/en unknown
- 1982-06-15 GB GB8217270A patent/GB2100268B/en not_active Expired
-
1991
- 1991-11-14 JP JP3297561A patent/JPH0798843B2/en not_active Expired - Lifetime
Also Published As
| Publication number | Publication date |
|---|---|
| FR2507607B1 (en) | 1986-08-14 |
| GB2100268A (en) | 1982-12-22 |
| DE3222498C2 (en) | 1994-04-07 |
| JPH0443924B2 (en) | 1992-07-20 |
| NL8202406A (en) | 1983-01-03 |
| LU84200A1 (en) | 1983-01-20 |
| BR8203490A (en) | 1983-06-07 |
| DE3222498A1 (en) | 1983-01-05 |
| NL190931C (en) | 1994-11-01 |
| PH19549A (en) | 1986-05-20 |
| IT1157210B (en) | 1987-02-11 |
| NL190931B (en) | 1994-06-01 |
| FR2507607A1 (en) | 1982-12-17 |
| AU8476782A (en) | 1982-12-23 |
| BE893522A (en) | 1982-12-15 |
| MX167645B (en) | 1993-03-31 |
| IT8248643A0 (en) | 1982-06-15 |
| ZA824064B (en) | 1983-04-27 |
| KR860001115B1 (en) | 1986-08-13 |
| JPH0798843B2 (en) | 1995-10-25 |
| JPS5823804A (en) | 1983-02-12 |
| GB2100268B (en) | 1984-09-19 |
| KR840000589A (en) | 1984-02-25 |
| AU554655B2 (en) | 1986-08-28 |
| JPH051111A (en) | 1993-01-08 |
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