CA1256245A - CONTROLLED DEGRADATION OR CRACKING OF .alpha.-OLEFIN POLYMERS - Google Patents
CONTROLLED DEGRADATION OR CRACKING OF .alpha.-OLEFIN POLYMERSInfo
- Publication number
- CA1256245A CA1256245A CA000497941A CA497941A CA1256245A CA 1256245 A CA1256245 A CA 1256245A CA 000497941 A CA000497941 A CA 000497941A CA 497941 A CA497941 A CA 497941A CA 1256245 A CA1256245 A CA 1256245A
- Authority
- CA
- Canada
- Prior art keywords
- peroxide
- extruder
- melt
- cracking
- mwd
- 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.)
- Expired
Links
Classifications
-
- 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
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
- B29C2948/00—Indexing scheme relating to extrusion moulding
- B29C2948/92—Measuring, controlling or regulating
- B29C2948/92504—Controlled parameter
- B29C2948/92704—Temperature
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
- B29C2948/00—Indexing scheme relating to extrusion moulding
- B29C2948/92—Measuring, controlling or regulating
- B29C2948/92819—Location or phase of control
- B29C2948/92857—Extrusion unit
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
- B29C48/00—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor
- B29C48/022—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor characterised by the choice of material
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29K—INDEXING SCHEME ASSOCIATED WITH SUBCLASSES B29B, B29C OR B29D, RELATING TO MOULDING MATERIALS OR TO MATERIALS FOR MOULDS, REINFORCEMENTS, FILLERS OR PREFORMED PARTS, e.g. INSERTS
- B29K2023/00—Use of polyalkenes or derivatives thereof as moulding material
- B29K2023/10—Polymers of propylene
- B29K2023/14—Copolymers of polypropylene
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29K—INDEXING SCHEME ASSOCIATED WITH SUBCLASSES B29B, B29C OR B29D, RELATING TO MOULDING MATERIALS OR TO MATERIALS FOR MOULDS, REINFORCEMENTS, FILLERS OR PREFORMED PARTS, e.g. INSERTS
- B29K2029/00—Use of polyvinylalcohols, polyvinylethers, polyvinylaldehydes, polyvinylketones or polyvinylketals or derivatives thereof as moulding material
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29K—INDEXING SCHEME ASSOCIATED WITH SUBCLASSES B29B, B29C OR B29D, RELATING TO MOULDING MATERIALS OR TO MATERIALS FOR MOULDS, REINFORCEMENTS, FILLERS OR PREFORMED PARTS, e.g. INSERTS
- B29K2105/00—Condition, form or state of moulded material or of the material to be shaped
- B29K2105/0002—Condition, form or state of moulded material or of the material to be shaped monomers or prepolymers
-
- 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
Abstract
A B S T R A C T
CONTROLLED DEGRADATION OR CRACKING OF ALPHA-OLEFIN POLYMERS
An improved process for the controlled reduction of average molecular weight and alteration of molecular weight distribution of C3-C8 alpha-monoolefin homopolymers or copolymers comprises adding a peroxide continuously at a programmed cyclic rate to the polymer or copolymer and heating the mixture in a melt extruder. m e rate of peroxide addition is varied at a frequency with a period longer than the decomposition time of the peroxide but shorter than the passage time of the mixture through the extruder, so as to achieve combinations of melt flow and molecular weight distribution for the polymer not possible with prior art steady rates of addition.
CWgH04
CONTROLLED DEGRADATION OR CRACKING OF ALPHA-OLEFIN POLYMERS
An improved process for the controlled reduction of average molecular weight and alteration of molecular weight distribution of C3-C8 alpha-monoolefin homopolymers or copolymers comprises adding a peroxide continuously at a programmed cyclic rate to the polymer or copolymer and heating the mixture in a melt extruder. m e rate of peroxide addition is varied at a frequency with a period longer than the decomposition time of the peroxide but shorter than the passage time of the mixture through the extruder, so as to achieve combinations of melt flow and molecular weight distribution for the polymer not possible with prior art steady rates of addition.
CWgH04
Description
CONTROLLED DEGRADATION OR CRACKING OF AI~HA-OLEFIN POL~MERS
This invention relates to an improved process for the production of alphaolefin polymers. More particularly, this invention relates to an improved process for the controLled degradation or "cracking" of C3-C8 alpha-monoolefin polymers or copolymers.
For many commercial end-uses, the melt-flow characteristics of C3+ polyolefins, especially polypropylene, are not suitable because of the relatively high molecular w~3ight (MW) of such polymer as it is originally produced in the synthesis process. Important end-uses where it has become well accepted that the melt flow characteristics of such polymers must be substantially improved are - in fibres and/or films as well as in various extruded and injection- and blow-moulded product grades.
In view of this need, it has been shown in the past that higher melt-flow characteristics can be achieved by controlled chain scission, which in effect reduces the molecular weight of the longer and thus high molecular weight chains. The average MW is reduced lcwering the melt viscosity. Furthermore, the molecular weight distribution (MWD) is significantly altered, primarily because of the reduction of the high MW fraction. Improvement of melt properties associated with reduction of melt elasticity results in reduced die swell in extrusion and reduced spin resonance in fibre spinning. mis chain cleavage is normally acccmplished by oxygen and/or free radiQl sources such as peroxides ~ he basic concept of accomplishing such degradation by utilizing perQxides is claimed in U.S. Patent No. 3,144,436, where a free radical initiator is introduoe d into a polymer melt in t~e absence of oxygen in a screw extruder. U.S. Patent No. 3,940,379 discloses a method for the degradation of propylene polymers to increase their melt flow rate which comprises contacting a propylene pol~mer with oxygen and an organic or inorganic peroxide, 3~
. ~ . .
.
' . . . ' ~
~25~iZ~
melting and working the resulting mixture in a high shear zone, and recovering an essentially odour-free propylene polymer. U.S. Patent No. 4,061,694 discloses the manufacture of propylene moulding compositions of improved impact strength by subjecting block copolymers of ethylene and propylene to controlled oxidative degradation under conditions essentially similar to those of the preceding patent. Other patents dealing with degradation of polypropylene include U.S. Patent Nos. 4,375,531; 3,862,265;
3,887,534; 3,898,209; 4,001,172; 4,087,486; 4,359,495; 4,378,451 and 4,387,185.
A new term has been coined for such degraded or cracked - polypropylene, that term being "controlled rheology" (CRi) polypropylene. Although controlled rheology polypropylene has been co~mercially available for several years, its similarities and differences fram "normal" or reactor polypropylene are just starting to be understood. CR polymers have a variety of advantages and disadvantages. The growing diversity of the polyolefin market is putting an increasing demand on polyolefin manufac~urers for product grades to fit a large variety of processing behaviours as well as bulk mechanical properties. Increased control over MW and M~D in the manufacturing process is a Fx~erful step in this direction.
Typically, the polypropylene producers have focused on the single property, "melt flow", when manufacturing CR polypropylene ?5 for specific products. ~owever, another property molecular weight distribution (MWD) is also critically important. As discussed by 8rcwn et al in "Molecular Weight Distribution and its Effect on Fiber Spinning", Fiber World, Vol. l, No. 2, pages 32 43 (March 1984), the three commonly used molecular weight averages are Mn, Mw, and Mz. These are obtained by three different averaging methods, referred to as "number", "weight", and "z" and are based on ratios of successively higher moments of the MWD. The MWD itself can be defined by various ratios of these averages, as follows:
.
; .
,: ' :: ' ' ; .
' : ' ., ;2~5 Q = Mw/Mn Z/ W
z/ n In some cases, these are inadequate to express a detailed description of the MWD as they are based on averaging processes. In this case a detailed "spectral ana]ysis" of the MWD is preferable, where separate segments of the MWD are specifically examined.
Polypropylene homopolymers of different MF have roughly the same shape of MWD when prepared by the same reactor process. With a CR resin, this MWD changes. The three molecular weight averages are all reduced in the CR process. m e fastest ~langing average is Mz, while the slowest is Mn. This is not surprising since the high molecular weight end of the MWD is the most changed by the CR
process. Also not surprising is that S decreases faster than Q, which decreases faster than R. After the CR process takes place, a MWD becomes skewed due to the preferential loss of the high molecular weight components. For a csmpletely random scission process, Q approaches a limiting value of 2.0, while R approaches 1.5.
Rheological (melt flcw) behaviour is very sensitive to the MWD, particularly to the high molecular weight portion of the M~D.
Reduction of the high molecular weight portion of the MWD with corresponding increase of the medium or low molecular weight portions of the MWD is referred to as "narrowing" of the M~D. The difference between "narrow" and "broad" MWD can have profound effects on melt processibility. For example, for two polypropylenes with the same melt flow index, but having different breadth of MWD, the polypropylene with the narrow MWD will generally show a reduced shear sensitivity over a wider shear range than that with the broad MWD. In the past it has not been possible to achieve independent variability of melt flow and molecular weight distribution without blending together various CR polymers or using different polymers from different polymerization conditions. I have disccvered a new method that permits the preparation of increased melt flow products ' :
.. . ... .
- - . : : . , :, : , : , .. : .. -';
.. .
:
~s~
along with control over the desired molecular weight distribution, without blending, using a single degradation or cracking process.
The present invention is directed to an improved process for making alpha-olefin polymers and copolymers of controlled melt flc~
and molecular weight distribution. In particular, the present invention is directed to an improvement in the process for the degradation or cracking modification of a C3-C8 alpha-monoolefin hc~x~olymer or copolymer, which process comprises adding about 0.001 to about 1.0 parts by weight of a pero~ide to 100 parts by weight of said hc~polymer or copo]ymer and heating the resulting mixture in a melt extruder at a temperature of from about 150 ~C to about 300 C, more usually at a ten~rature of frc~m about 190 ~C to a~out 260 C. Prior art methods of preparing CR polyolefins involve either (1) prior mixing of a fixed amount of peroxide with polyolefin in a batch process or (2) a constant rate of addition of the peroxide to the polyolefin in a continuous process. m e improvement claimed herein is concerned with a continuous process wherein the rate of addition is varied in a cyclic pattern during the process. An essential feature of this cyclic variation is that the rate of addition of said peroxide is varied at a frequency with a period longer than the decomposition time of said peroxide, but shorter than the passage time of said mixture through said extruder.
A highly cracked polypropylene (PP) can be blended in minor proportion with an uncracked PP to increase melt flow a~ove that of the uncracked PP. This blend may have melt flow of a non-blended PP
directly cracked by the currently employed pe~-oxide cracking technology. Hcwever, although the blend and directly-cracked material have equal melt flcws, they may have distinctly different M~D's. mis may be understood by considering what cracking does to - the MWD. Cracking reduces the very hi~h MW fraction and, at the same time, increases the mid-MW fraction and shifts the peak of the M~D to lower MW. m e very lcw MW fraction remains virtually unchanged. In a blend containing a major amount of uncracked , : -:: , , ~ .
- ~ , .
4~
material, the high MW fraction is, therefore, mostly retained. The minor amount of cracked material supplies more mid-MW fraction shifted to lower values. me net result is that the blend can be designed to have a broad MWD, approaching that of the uncracked material. The cracked component in the blend then serves more as a pGwerful flow pr~ ter to achieve the desired blend MF, whereas the uncracked portion of the blend supplies the high molecular weight to modify melt processing as well as bulk properties of the product.
lo I have shcwn that in-situ production of a desired proportion of cracked and uncracked PP and subsequent blending of these can be done in the extruder where cracking takes place. Briefl~, the method is conceptualized as follcws: The rate of peroxide injection into the powder basestock is strategically progra~med so that portions of the PP will be left uncracked, whereas other portions are "overcracked" relative to usual level of cracking. The rate of injection may be varied or "cycled" at a frequency with a period longer than reaction time, but shorter than passage time through the extruder. This is possible beQ use the time required for cracking is much shorter than extruder passage time. Thus, cracking may be confined to the first (upstream) half of the extruder, where mixing is relatively poor, whereas mixing or blending of the cracked and uncracked materials can occur in the second half of the extruder where mixing is more efficient.
General considerations relating to adjustment of MWD and its effect on ~elt and bulk properties are summarized in Figure 1 as a simplified representation of "addition of a lcw or high ~ tail".
These "tails" are exaggerated in the figure for clarity.
Figure 2 also shows a simplified representation, the achievement of "broad" MWD by four different cycling programs. Here again, it is evid~nt that pulsing of the peroxide injection rate to achieve "over-cracking", "under-cracking" or "no-cracking" during the cycle can only be possible because the pulse period is selected -~ .
.
:
.
.
dj~ t j between the relatively rapid time of peroxide decomposition and the relatively slow extruder passage time.
Figure 2a shows the prior art method of constant addition of peroxide to attain desired melt flcw. Figure 2b shows the addition 5 of peroxide according to a sinusoidal wave pattern. Figure 2c shcws the addition of peroxide by a pulsed square addition method to obtain a low MW tail, while Figure 2d shcws a pulsed sgtlare addition method to obtain a high MW tail. Another variation is shown in Figure 2e, which is a pulsed square wave having a relatively short high pulse alternating with a relatively long pulse of zero amplitude. This would produce a blend having a minor amount of "over-cracked" cGmponent and a major uncracked componentO
This is the method actually used in the illustrative example.
The dotted line in Figures 2b, c, d and e is a symbolic representation of the average melt flow of the product held constant corresponding to the dotted line in Figure 2a for the prior art method of peroxide addition.
The present invention has particular application for propylene polymers useful in fibre applications. Both melt flcw ~MY) and M~D
of the polypropylene affect fibre properties. me effects of MF and MWD can be broadly related to processibility. In general, strength will decrease, and the draw ratio and processibility rate will increase as the MF increases. m e effects of MWD on processibility are profound but are more difficult to define. Table 1 shows some general trends of properties as they relate to MF and MhD. mese are generalizations, which may not always hold true for different processing conditions. Nevertheless, the table dces provide some guidance for appropriate adjustment of MF and MWD:
..
~z~
-TRENDS FOR POLYPROPYLENE RESINS PROCESSED UNDER IDENTIQ L CONDITICNS
- Resins with same Resins with same - shape MWD Trend MF Trend as Property as MF increases. MWD narrGws.
_ _ _ M~ximum obtainable draw ratio Increases Decreases Maximum obtainable melt drawdown Increases Draw resonance Decreases Ease of orientation Decreases Extrudability at die Increases Fibre strength Decreases Elongation at a given draw ratio Increases Decreases Tenacity at a given draw ratio Decreases Increases Modulus at a given draw ratio Decreases Orientation at a given draw ratio Decreases Birefiringence at a given draw ratio Decreases Increases Processing speed Increases Increases In cracking a given polyolefin according to the prior art, a single steady rate of addition of percKide in the continuous process results in a raising of the MF and narrcwing of the MWD.
With the exception of a general raising of processing speed, Table 1 shows that these changes in MF and MWD will produce opposite directions of changes, respectively, in other processing properties. Because of this, the advantage of cracking may therefore be reduced or even become a disadvantage for some aspects of processing. The MF and MWD cannot be independently controlled in the prior art, since for a given starting material, the final MWD
is determined by the extent of cracking or by the final MF. me manufacturer is effectively "locked-in" to accepting a given set of processing properties dependent on his selection of desired MF. The primary advantage of the invention in this context is the : .
, . ~ ' - :
- . , .
:
., .
.
-- ~2S~:i2 ~- 8 --capability of independent control of M~D for a given MF by use of an added degree of freedcm, namely the cycling mcde and/or frequency used in the peroxide addition.
The polymers that are modified or degraded according to the present invention are hamopolymers and copolymers of C3 ~o C8 alpha-monoolefins. Polypropylene is preferred. Hcwever, other polyolefins which can be processed according to the technique of this invention include propylene/ethylene impact copolymers, polybutene-l, poly-3-methylbutene-L, poly-4-methylpentene-1, propylene/4-methylpentene-1 copolymers, polyallomers and the like.
With regard to the propylene polymPr, starting melt flows are about 0.2 to about 20, preferably about 0.5 to about 3Ø
A key aspect of the present invention is that the peroxide employed for cracking must have a decomposition time which is shorter than the passage time of the polymer/peroxide mixture through the melt extruder. For example, the passage time of a polymer through a 32'xl' Egan face-cutting extruder is about two minutes. Therefore, the peroxide employed with such a machine must have a decomposition time shorter than two minutes. Further, the ?O rate of peroxide addition is varied at a frequency with a period longer than the decomposition time of the peraxide. Accordingly, it is generally preferred that the per~cide have a decomposition time (defined as the half-life at the extrusion temperature) of about 1 to about 30 seconds. If the peroxide has a half-life of less than one second, the peroxide is too unstable and can be deccmposed before reacting with the polymer to the desired extent. If the half-life is more than abcut 30 seco~ds, then reaction may be incomplete and/or selection of the frequency of addition may be too constrained to achieve the desired results. Preferred pero~ides are those which have relatively high decomposition temperatures and produce volatile deccmposition products, the latter being relatively non-taxic and with minimal residual odour. The peroxide of choice is 2,5-dimethyl-2,5-di(t-butylperoxy)hexane (Lupersol 101, manufactured by Lucidol, a division of the Pennwalt Co.). Mbny * Trade Mar]c '' ' ' '' :
.: ' ' - .
~ . .
-_ 9 _ 3293-2615 peroxides fit this category and choice is determined by economic considerations and physical form of the peroxide relative to efficiency of utilization. Many of the peroxides that are compatible with this invention are diaIkyl peroxides but are not limited to this class. Specific examples manufactured by the Lucidol Company are dicumyl peroxide (Luperox 500), di-t-butyl peroxide, t-butyl cumyl peroxide (Lupersol 801) and
This invention relates to an improved process for the production of alphaolefin polymers. More particularly, this invention relates to an improved process for the controLled degradation or "cracking" of C3-C8 alpha-monoolefin polymers or copolymers.
For many commercial end-uses, the melt-flow characteristics of C3+ polyolefins, especially polypropylene, are not suitable because of the relatively high molecular w~3ight (MW) of such polymer as it is originally produced in the synthesis process. Important end-uses where it has become well accepted that the melt flow characteristics of such polymers must be substantially improved are - in fibres and/or films as well as in various extruded and injection- and blow-moulded product grades.
In view of this need, it has been shown in the past that higher melt-flow characteristics can be achieved by controlled chain scission, which in effect reduces the molecular weight of the longer and thus high molecular weight chains. The average MW is reduced lcwering the melt viscosity. Furthermore, the molecular weight distribution (MWD) is significantly altered, primarily because of the reduction of the high MW fraction. Improvement of melt properties associated with reduction of melt elasticity results in reduced die swell in extrusion and reduced spin resonance in fibre spinning. mis chain cleavage is normally acccmplished by oxygen and/or free radiQl sources such as peroxides ~ he basic concept of accomplishing such degradation by utilizing perQxides is claimed in U.S. Patent No. 3,144,436, where a free radical initiator is introduoe d into a polymer melt in t~e absence of oxygen in a screw extruder. U.S. Patent No. 3,940,379 discloses a method for the degradation of propylene polymers to increase their melt flow rate which comprises contacting a propylene pol~mer with oxygen and an organic or inorganic peroxide, 3~
. ~ . .
.
' . . . ' ~
~25~iZ~
melting and working the resulting mixture in a high shear zone, and recovering an essentially odour-free propylene polymer. U.S. Patent No. 4,061,694 discloses the manufacture of propylene moulding compositions of improved impact strength by subjecting block copolymers of ethylene and propylene to controlled oxidative degradation under conditions essentially similar to those of the preceding patent. Other patents dealing with degradation of polypropylene include U.S. Patent Nos. 4,375,531; 3,862,265;
3,887,534; 3,898,209; 4,001,172; 4,087,486; 4,359,495; 4,378,451 and 4,387,185.
A new term has been coined for such degraded or cracked - polypropylene, that term being "controlled rheology" (CRi) polypropylene. Although controlled rheology polypropylene has been co~mercially available for several years, its similarities and differences fram "normal" or reactor polypropylene are just starting to be understood. CR polymers have a variety of advantages and disadvantages. The growing diversity of the polyolefin market is putting an increasing demand on polyolefin manufac~urers for product grades to fit a large variety of processing behaviours as well as bulk mechanical properties. Increased control over MW and M~D in the manufacturing process is a Fx~erful step in this direction.
Typically, the polypropylene producers have focused on the single property, "melt flow", when manufacturing CR polypropylene ?5 for specific products. ~owever, another property molecular weight distribution (MWD) is also critically important. As discussed by 8rcwn et al in "Molecular Weight Distribution and its Effect on Fiber Spinning", Fiber World, Vol. l, No. 2, pages 32 43 (March 1984), the three commonly used molecular weight averages are Mn, Mw, and Mz. These are obtained by three different averaging methods, referred to as "number", "weight", and "z" and are based on ratios of successively higher moments of the MWD. The MWD itself can be defined by various ratios of these averages, as follows:
.
; .
,: ' :: ' ' ; .
' : ' ., ;2~5 Q = Mw/Mn Z/ W
z/ n In some cases, these are inadequate to express a detailed description of the MWD as they are based on averaging processes. In this case a detailed "spectral ana]ysis" of the MWD is preferable, where separate segments of the MWD are specifically examined.
Polypropylene homopolymers of different MF have roughly the same shape of MWD when prepared by the same reactor process. With a CR resin, this MWD changes. The three molecular weight averages are all reduced in the CR process. m e fastest ~langing average is Mz, while the slowest is Mn. This is not surprising since the high molecular weight end of the MWD is the most changed by the CR
process. Also not surprising is that S decreases faster than Q, which decreases faster than R. After the CR process takes place, a MWD becomes skewed due to the preferential loss of the high molecular weight components. For a csmpletely random scission process, Q approaches a limiting value of 2.0, while R approaches 1.5.
Rheological (melt flcw) behaviour is very sensitive to the MWD, particularly to the high molecular weight portion of the M~D.
Reduction of the high molecular weight portion of the MWD with corresponding increase of the medium or low molecular weight portions of the MWD is referred to as "narrowing" of the M~D. The difference between "narrow" and "broad" MWD can have profound effects on melt processibility. For example, for two polypropylenes with the same melt flow index, but having different breadth of MWD, the polypropylene with the narrow MWD will generally show a reduced shear sensitivity over a wider shear range than that with the broad MWD. In the past it has not been possible to achieve independent variability of melt flow and molecular weight distribution without blending together various CR polymers or using different polymers from different polymerization conditions. I have disccvered a new method that permits the preparation of increased melt flow products ' :
.. . ... .
- - . : : . , :, : , : , .. : .. -';
.. .
:
~s~
along with control over the desired molecular weight distribution, without blending, using a single degradation or cracking process.
The present invention is directed to an improved process for making alpha-olefin polymers and copolymers of controlled melt flc~
and molecular weight distribution. In particular, the present invention is directed to an improvement in the process for the degradation or cracking modification of a C3-C8 alpha-monoolefin hc~x~olymer or copolymer, which process comprises adding about 0.001 to about 1.0 parts by weight of a pero~ide to 100 parts by weight of said hc~polymer or copo]ymer and heating the resulting mixture in a melt extruder at a temperature of from about 150 ~C to about 300 C, more usually at a ten~rature of frc~m about 190 ~C to a~out 260 C. Prior art methods of preparing CR polyolefins involve either (1) prior mixing of a fixed amount of peroxide with polyolefin in a batch process or (2) a constant rate of addition of the peroxide to the polyolefin in a continuous process. m e improvement claimed herein is concerned with a continuous process wherein the rate of addition is varied in a cyclic pattern during the process. An essential feature of this cyclic variation is that the rate of addition of said peroxide is varied at a frequency with a period longer than the decomposition time of said peroxide, but shorter than the passage time of said mixture through said extruder.
A highly cracked polypropylene (PP) can be blended in minor proportion with an uncracked PP to increase melt flow a~ove that of the uncracked PP. This blend may have melt flow of a non-blended PP
directly cracked by the currently employed pe~-oxide cracking technology. Hcwever, although the blend and directly-cracked material have equal melt flcws, they may have distinctly different M~D's. mis may be understood by considering what cracking does to - the MWD. Cracking reduces the very hi~h MW fraction and, at the same time, increases the mid-MW fraction and shifts the peak of the M~D to lower MW. m e very lcw MW fraction remains virtually unchanged. In a blend containing a major amount of uncracked , : -:: , , ~ .
- ~ , .
4~
material, the high MW fraction is, therefore, mostly retained. The minor amount of cracked material supplies more mid-MW fraction shifted to lower values. me net result is that the blend can be designed to have a broad MWD, approaching that of the uncracked material. The cracked component in the blend then serves more as a pGwerful flow pr~ ter to achieve the desired blend MF, whereas the uncracked portion of the blend supplies the high molecular weight to modify melt processing as well as bulk properties of the product.
lo I have shcwn that in-situ production of a desired proportion of cracked and uncracked PP and subsequent blending of these can be done in the extruder where cracking takes place. Briefl~, the method is conceptualized as follcws: The rate of peroxide injection into the powder basestock is strategically progra~med so that portions of the PP will be left uncracked, whereas other portions are "overcracked" relative to usual level of cracking. The rate of injection may be varied or "cycled" at a frequency with a period longer than reaction time, but shorter than passage time through the extruder. This is possible beQ use the time required for cracking is much shorter than extruder passage time. Thus, cracking may be confined to the first (upstream) half of the extruder, where mixing is relatively poor, whereas mixing or blending of the cracked and uncracked materials can occur in the second half of the extruder where mixing is more efficient.
General considerations relating to adjustment of MWD and its effect on ~elt and bulk properties are summarized in Figure 1 as a simplified representation of "addition of a lcw or high ~ tail".
These "tails" are exaggerated in the figure for clarity.
Figure 2 also shows a simplified representation, the achievement of "broad" MWD by four different cycling programs. Here again, it is evid~nt that pulsing of the peroxide injection rate to achieve "over-cracking", "under-cracking" or "no-cracking" during the cycle can only be possible because the pulse period is selected -~ .
.
:
.
.
dj~ t j between the relatively rapid time of peroxide decomposition and the relatively slow extruder passage time.
Figure 2a shows the prior art method of constant addition of peroxide to attain desired melt flcw. Figure 2b shows the addition 5 of peroxide according to a sinusoidal wave pattern. Figure 2c shcws the addition of peroxide by a pulsed square addition method to obtain a low MW tail, while Figure 2d shcws a pulsed sgtlare addition method to obtain a high MW tail. Another variation is shown in Figure 2e, which is a pulsed square wave having a relatively short high pulse alternating with a relatively long pulse of zero amplitude. This would produce a blend having a minor amount of "over-cracked" cGmponent and a major uncracked componentO
This is the method actually used in the illustrative example.
The dotted line in Figures 2b, c, d and e is a symbolic representation of the average melt flow of the product held constant corresponding to the dotted line in Figure 2a for the prior art method of peroxide addition.
The present invention has particular application for propylene polymers useful in fibre applications. Both melt flcw ~MY) and M~D
of the polypropylene affect fibre properties. me effects of MF and MWD can be broadly related to processibility. In general, strength will decrease, and the draw ratio and processibility rate will increase as the MF increases. m e effects of MWD on processibility are profound but are more difficult to define. Table 1 shows some general trends of properties as they relate to MF and MhD. mese are generalizations, which may not always hold true for different processing conditions. Nevertheless, the table dces provide some guidance for appropriate adjustment of MF and MWD:
..
~z~
-TRENDS FOR POLYPROPYLENE RESINS PROCESSED UNDER IDENTIQ L CONDITICNS
- Resins with same Resins with same - shape MWD Trend MF Trend as Property as MF increases. MWD narrGws.
_ _ _ M~ximum obtainable draw ratio Increases Decreases Maximum obtainable melt drawdown Increases Draw resonance Decreases Ease of orientation Decreases Extrudability at die Increases Fibre strength Decreases Elongation at a given draw ratio Increases Decreases Tenacity at a given draw ratio Decreases Increases Modulus at a given draw ratio Decreases Orientation at a given draw ratio Decreases Birefiringence at a given draw ratio Decreases Increases Processing speed Increases Increases In cracking a given polyolefin according to the prior art, a single steady rate of addition of percKide in the continuous process results in a raising of the MF and narrcwing of the MWD.
With the exception of a general raising of processing speed, Table 1 shows that these changes in MF and MWD will produce opposite directions of changes, respectively, in other processing properties. Because of this, the advantage of cracking may therefore be reduced or even become a disadvantage for some aspects of processing. The MF and MWD cannot be independently controlled in the prior art, since for a given starting material, the final MWD
is determined by the extent of cracking or by the final MF. me manufacturer is effectively "locked-in" to accepting a given set of processing properties dependent on his selection of desired MF. The primary advantage of the invention in this context is the : .
, . ~ ' - :
- . , .
:
., .
.
-- ~2S~:i2 ~- 8 --capability of independent control of M~D for a given MF by use of an added degree of freedcm, namely the cycling mcde and/or frequency used in the peroxide addition.
The polymers that are modified or degraded according to the present invention are hamopolymers and copolymers of C3 ~o C8 alpha-monoolefins. Polypropylene is preferred. Hcwever, other polyolefins which can be processed according to the technique of this invention include propylene/ethylene impact copolymers, polybutene-l, poly-3-methylbutene-L, poly-4-methylpentene-1, propylene/4-methylpentene-1 copolymers, polyallomers and the like.
With regard to the propylene polymPr, starting melt flows are about 0.2 to about 20, preferably about 0.5 to about 3Ø
A key aspect of the present invention is that the peroxide employed for cracking must have a decomposition time which is shorter than the passage time of the polymer/peroxide mixture through the melt extruder. For example, the passage time of a polymer through a 32'xl' Egan face-cutting extruder is about two minutes. Therefore, the peroxide employed with such a machine must have a decomposition time shorter than two minutes. Further, the ?O rate of peroxide addition is varied at a frequency with a period longer than the decomposition time of the peraxide. Accordingly, it is generally preferred that the per~cide have a decomposition time (defined as the half-life at the extrusion temperature) of about 1 to about 30 seconds. If the peroxide has a half-life of less than one second, the peroxide is too unstable and can be deccmposed before reacting with the polymer to the desired extent. If the half-life is more than abcut 30 seco~ds, then reaction may be incomplete and/or selection of the frequency of addition may be too constrained to achieve the desired results. Preferred pero~ides are those which have relatively high decomposition temperatures and produce volatile deccmposition products, the latter being relatively non-taxic and with minimal residual odour. The peroxide of choice is 2,5-dimethyl-2,5-di(t-butylperoxy)hexane (Lupersol 101, manufactured by Lucidol, a division of the Pennwalt Co.). Mbny * Trade Mar]c '' ' ' '' :
.: ' ' - .
~ . .
-_ 9 _ 3293-2615 peroxides fit this category and choice is determined by economic considerations and physical form of the peroxide relative to efficiency of utilization. Many of the peroxides that are compatible with this invention are diaIkyl peroxides but are not limited to this class. Specific examples manufactured by the Lucidol Company are dicumyl peroxide (Luperox 500), di-t-butyl peroxide, t-butyl cumyl peroxide (Lupersol 801) and
2,5-dimethyl-2,5-bis(t-butylpe mxy)hexene-3 (Lupersol 130`). The amount of peroxide and the cracki~g temperature depend upon the melt flcws of the starting polymers and the desired melt flow of the final composition. Typical amounts of peroxide are between about 100 parts by weight per million parts by weight total polymer (pF~W) and about 10,000 ppmw~ preferably be~ween akout 200 ppmw and about 1,000 ppm w. Typical cracking temperatures are between about 150 C and about 300 C, preferably between about 190 C and about 260 C.
Preferably the peroxide is added to the polymer powder prior to injection into the extruder. However, it is also possible to add the peroxide directly into the polymer melt in the extruder. If it is added in this fashion, the point of injection should be do~lstream at a portion of the extruder where complete melting of the ext~udate is first achieved. A~vantage of direct addition of the peroxide to the melt is that reaction is not delayed by the time required to achieve the melt temperature from the pcwder entry t~mperature. me result is a shorter reaction time increasing the range available for frequency alteration.
Additional components may be added to the above compositions as long as the amount of peroxide and poly(alpha-monoolefin) are within the ranges specified above. These ccmpositions may be compounded further with other poiymers, oils, fillers, blcwing agents, reinforcements or irnpact modifiers such as rubbers and rubber/thermoplastic blends, antio~idants, stabilizers, fire retardants, antiblocking agents and other rubber and plastic *Trade Marks :, - ' ' , ' : ,. . ' ' .
. ~ . .
compounding ingredients without departing from the scope of this invention.
One possible arrangement for the injection pulsing involves the use of a 3-way valve. The 3-way valve is periodically actuated by a timed solenoid to provide the pulse of peroxide solution injection. Peroxide may be returned to the storage tank on the "off" period. An effective means for pulsing might also be provided by simply rotating the valve at constant speed. In this case, pulses would be sinusoidally shaped rather than rectangular. A
1o constant pressure device would be necessary in any case for normal or direct injection. To avoid excessive repeated pumping of a given portion of peroxide solution (which causes degradation) an excess of peroxide solution should be in the reservoir tank. Ideally, the volume of solution should be at least N times that actually used, where N is the ratio of off/on times. This would allow an average of one pumping cycle for each portion of peroxide.
As used in the examples, melt flow is the amount (in grams per 10 minutes) of polymer which flows through a capillary with relatively smail L/D ratio under AS~M D 1238 Condition L at 230 C.
This measurement is done under cons~ant stress. Neglecting end effects, the shear rate experienced by a polymer in a melt indexer with capillary of radius R is given by:
y = 4Q
~R
where Q is the volumetric flow rate and R is 0.1045 am. mus polypropylene with a density of 0.7386 at 230 C and a melt flow value of 'X' will experience a shear rate of about:
y= 2.5(X)sec~l in the melt indexer. For most commercial polypropylenes (MF in the range of 1-20) the melt indexer relates to behaviour at moderately low shear rate (2.5-50 sec 1). This is important to remember, since the area of real interest might be the shear flow behaviour at the 30 spinnerette. This will generally be on the order of 10 to 1,000 ~' ' ' ' ~
~ ; . .
~2S624~i times the shear rate experienced in the melt indexer, for typical fiber spinning applicationsO Even at the lower shear processes encountered in extrusion or injection m~ulding, shear rates may be many times that experienced in the ~lelt indexer. Since polymers are highly non-Newtonian (viscosity is dependent on shear rate), melt flc~ index may be misleading in rc~nking processibility speeds of different product grades.
To illustrate the invention, the following illustrative embodiment is given. It is to be ~mderstood, hc~ver, that the embodiment is given for illustration only and the invention is not to be regarded as limited to any of the specific materials or cc)nditions used in the specific enibodiment.
m e illustrative example describes a test of the peraxide cycled addition conducted at a plant scale level. m e extruder used had twelve-inch diameter and produced 10,000 lbs of pelletized polypropylene per hour. Starting material was polypropylene with a melt flow of 1.5 and cracking was conducted to obtain a melt flow of 4.5+0.2. At this level of cracking, destruction of the higher MW
fraction of the M~D is significant but not extensive. me increased MF was necessary to achieve the desired processing speed, yet the small changes in MWD resulted in some undesirable changes in processing behaviour (fibre-spinning application) when the conventional (non-pulsed) cracking technique was used. The use of the pulsed method succeeded in altering the MWD in the desired 2~ direction. Table 2 shcws the MWD spectral analyses of the pulsed and non-pulsed cracked products obtained by high temperature gel permeation chromatography (GæC). The more detailed spectral analysis was required to detect MWD differences, since the Q, R and S values tended to obscure the subtle changes in the MWD caused by the pulsing technique.
The pulsing technique used is the one described by Figure ?e.
Table 2 shows the spectral analyses for the two pulsing variations (pulsed-into-pcwder and pulsed-into-melt) and the conventional steady variation. Also given in the table are the melt flows as .
, .
,: , ' ' ~ . ' :, . , : . . . . .
'-' '. '' " ' ''' ''' ~-',' ' " -' .
. : .
' : ,
Preferably the peroxide is added to the polymer powder prior to injection into the extruder. However, it is also possible to add the peroxide directly into the polymer melt in the extruder. If it is added in this fashion, the point of injection should be do~lstream at a portion of the extruder where complete melting of the ext~udate is first achieved. A~vantage of direct addition of the peroxide to the melt is that reaction is not delayed by the time required to achieve the melt temperature from the pcwder entry t~mperature. me result is a shorter reaction time increasing the range available for frequency alteration.
Additional components may be added to the above compositions as long as the amount of peroxide and poly(alpha-monoolefin) are within the ranges specified above. These ccmpositions may be compounded further with other poiymers, oils, fillers, blcwing agents, reinforcements or irnpact modifiers such as rubbers and rubber/thermoplastic blends, antio~idants, stabilizers, fire retardants, antiblocking agents and other rubber and plastic *Trade Marks :, - ' ' , ' : ,. . ' ' .
. ~ . .
compounding ingredients without departing from the scope of this invention.
One possible arrangement for the injection pulsing involves the use of a 3-way valve. The 3-way valve is periodically actuated by a timed solenoid to provide the pulse of peroxide solution injection. Peroxide may be returned to the storage tank on the "off" period. An effective means for pulsing might also be provided by simply rotating the valve at constant speed. In this case, pulses would be sinusoidally shaped rather than rectangular. A
1o constant pressure device would be necessary in any case for normal or direct injection. To avoid excessive repeated pumping of a given portion of peroxide solution (which causes degradation) an excess of peroxide solution should be in the reservoir tank. Ideally, the volume of solution should be at least N times that actually used, where N is the ratio of off/on times. This would allow an average of one pumping cycle for each portion of peroxide.
As used in the examples, melt flow is the amount (in grams per 10 minutes) of polymer which flows through a capillary with relatively smail L/D ratio under AS~M D 1238 Condition L at 230 C.
This measurement is done under cons~ant stress. Neglecting end effects, the shear rate experienced by a polymer in a melt indexer with capillary of radius R is given by:
y = 4Q
~R
where Q is the volumetric flow rate and R is 0.1045 am. mus polypropylene with a density of 0.7386 at 230 C and a melt flow value of 'X' will experience a shear rate of about:
y= 2.5(X)sec~l in the melt indexer. For most commercial polypropylenes (MF in the range of 1-20) the melt indexer relates to behaviour at moderately low shear rate (2.5-50 sec 1). This is important to remember, since the area of real interest might be the shear flow behaviour at the 30 spinnerette. This will generally be on the order of 10 to 1,000 ~' ' ' ' ~
~ ; . .
~2S624~i times the shear rate experienced in the melt indexer, for typical fiber spinning applicationsO Even at the lower shear processes encountered in extrusion or injection m~ulding, shear rates may be many times that experienced in the ~lelt indexer. Since polymers are highly non-Newtonian (viscosity is dependent on shear rate), melt flc~ index may be misleading in rc~nking processibility speeds of different product grades.
To illustrate the invention, the following illustrative embodiment is given. It is to be ~mderstood, hc~ver, that the embodiment is given for illustration only and the invention is not to be regarded as limited to any of the specific materials or cc)nditions used in the specific enibodiment.
m e illustrative example describes a test of the peraxide cycled addition conducted at a plant scale level. m e extruder used had twelve-inch diameter and produced 10,000 lbs of pelletized polypropylene per hour. Starting material was polypropylene with a melt flow of 1.5 and cracking was conducted to obtain a melt flow of 4.5+0.2. At this level of cracking, destruction of the higher MW
fraction of the M~D is significant but not extensive. me increased MF was necessary to achieve the desired processing speed, yet the small changes in MWD resulted in some undesirable changes in processing behaviour (fibre-spinning application) when the conventional (non-pulsed) cracking technique was used. The use of the pulsed method succeeded in altering the MWD in the desired 2~ direction. Table 2 shcws the MWD spectral analyses of the pulsed and non-pulsed cracked products obtained by high temperature gel permeation chromatography (GæC). The more detailed spectral analysis was required to detect MWD differences, since the Q, R and S values tended to obscure the subtle changes in the MWD caused by the pulsing technique.
The pulsing technique used is the one described by Figure ?e.
Table 2 shows the spectral analyses for the two pulsing variations (pulsed-into-pcwder and pulsed-into-melt) and the conventional steady variation. Also given in the table are the melt flows as .
, .
,: , ' ' ~ . ' :, . , : . . . . .
'-' '. '' " ' ''' ''' ~-',' ' " -' .
. : .
' : ,
3~25~2~i well as the values for Mn, ~, Mz, Q, R and S for the three variations. The following conditions were used for delivery of a 50% mineral oil solution of peroxide 2,5-dimethyl-2,5-di(t-butyl-peroxy)hexane to achieve the desired melt flcw.
STEADY INTO PCWDER (Conventional): 22 cc/min.
PULSED INTO PCWDER: peroxide injected into the powder crammer feed to the extruder, 1.4 seconds "on"; 23 seconds "off" at 55 cc/min.
PULSED INTO ME1T: peroxide in~ected into the extruder melt, 1.5 seconds "on"; 12.5 seconds "off" at 100 cc/min.
Table 2 shows the spectral analyses to be clearl~ different for the three variations. Compared to the conventional "steady into powder", the "pulsed into powder" shows a definite shift to increased amount of higher molecular weights compensated by reduction in amount of lower molecular weights. A molecular weight shift is also apparent for the "pulsed into melt", but is more to an increase in the amount of the midrange molecular weight compensated by a reduction in the amount of lower molecular weights.
" .
, , ` .' :.
~;25~ S
STEADY INTO PCWDER (Conventional): 22 cc/min.
PULSED INTO PCWDER: peroxide injected into the powder crammer feed to the extruder, 1.4 seconds "on"; 23 seconds "off" at 55 cc/min.
PULSED INTO ME1T: peroxide in~ected into the extruder melt, 1.5 seconds "on"; 12.5 seconds "off" at 100 cc/min.
Table 2 shows the spectral analyses to be clearl~ different for the three variations. Compared to the conventional "steady into powder", the "pulsed into powder" shows a definite shift to increased amount of higher molecular weights compensated by reduction in amount of lower molecular weights. A molecular weight shift is also apparent for the "pulsed into melt", but is more to an increase in the amount of the midrange molecular weight compensated by a reduction in the amount of lower molecular weights.
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, , ` .' :.
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Claims (10)
1. In the process for the degradation modification of a C3-C8 alpha-monoolefin homopolymer or copolymer, which process comprises adding about 0.001 to about 1.0 parts by weight of a peroxide to 100 parts by weight of said homopolymer or copolymer and heating the resulting mixture in a melt extruder at a temperature of from about 150 °C to about 300 °C, the improvement wherein the rate of addition of said peroxide is cyclically varied at a frequency with a period longer than the decomposition time of said peroxide, but shorter than the passage time of said mixture through said extruder.
2. The process according to claim 1 wherein said homopolymer is a propylene homopolymer.
3. The process according to claim 2 wherein said propylene homopolymer has a melt flow of about 0.5 to about 20.
4. The process according to claim 1 wherein said peroxide decomposition time is the half-life of the peroxide at the temperature in said extruder.
5. me process according to claim 4 wherein said peroxide has a half-life at about 1 second to about 30 seconds.
6. The process according to claim 5 wherein said passage time in said extruder is between about 0.5 and about 5 minutes.
7. m e process according to claim 1 wherein said peroxide is mixed with said homopolymer or copolymer prior to injection into said extruder.
8. The process according to claim 1 wherein said peroxide is added into said extruder separately from the injection of said homopolymer or copolymer.
9. The process according to claim 1 wherein the rate of addition of said peroxide is varied continuously.
10. The process according to claim 1 wherein the rate of addition of said peroxide is varied intermittently.
.
.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US06/683,748 US4578430A (en) | 1984-12-19 | 1984-12-19 | Controlled degradation or cracking of alpha-olefin polymers |
| US683,748 | 1984-12-19 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1256245A true CA1256245A (en) | 1989-06-20 |
Family
ID=24745292
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000497941A Expired CA1256245A (en) | 1984-12-19 | 1985-12-18 | CONTROLLED DEGRADATION OR CRACKING OF .alpha.-OLEFIN POLYMERS |
Country Status (18)
| Country | Link |
|---|---|
| US (1) | US4578430A (en) |
| EP (1) | EP0185434B1 (en) |
| JP (1) | JPH0657728B2 (en) |
| KR (1) | KR930005820B1 (en) |
| CN (1) | CN1003789B (en) |
| AR (1) | AR242597A1 (en) |
| AT (1) | ATE50269T1 (en) |
| AU (1) | AU577432B2 (en) |
| BR (1) | BR8506362A (en) |
| CA (1) | CA1256245A (en) |
| DE (1) | DE3575934D1 (en) |
| ES (1) | ES8702445A1 (en) |
| HK (1) | HK54590A (en) |
| IN (1) | IN165809B (en) |
| NO (1) | NO165844C (en) |
| NZ (1) | NZ214593A (en) |
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| ZA (1) | ZA859682B (en) |
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| US3862265A (en) * | 1971-04-09 | 1975-01-21 | Exxon Research Engineering Co | Polymers with improved properties and process therefor |
| JPS5148196B2 (en) * | 1972-03-11 | 1976-12-18 | ||
| US4001172A (en) * | 1972-04-03 | 1977-01-04 | Exxon Research And Engineering Company | Polymers with improved properties and process therefor |
| US3940379A (en) * | 1973-05-21 | 1976-02-24 | Dart Industries, Inc. | Process for controlled degradation of propylene polymers |
| US3898209A (en) * | 1973-11-21 | 1975-08-05 | Exxon Research Engineering Co | Process for controlling rheology of C{HD 3{B {30 {0 polyolefins |
| US4087486A (en) * | 1975-05-15 | 1978-05-02 | Standard Oil Company (Indiana) | Polypropylene composition containing EPR |
| US4060569A (en) * | 1975-12-24 | 1977-11-29 | Petrolite Corporation | Hydrocarbon polymers |
| US4061694A (en) * | 1976-12-21 | 1977-12-06 | Dart Industries Inc. | Low temperature impact strength molding compositions |
| US4239546A (en) * | 1978-07-21 | 1980-12-16 | Petrolite Corporation | Hydrocarbon polymers to improve the hardness of waxes |
| US4224204A (en) * | 1979-03-16 | 1980-09-23 | Petrolite Corporation | Use of hydrocarbon polymers to improve oil-containing waxes |
| US4387185A (en) * | 1981-02-25 | 1983-06-07 | Shell Oil Company | Cracked blend of propylene copolymer and E/VA |
| US4359495A (en) * | 1981-02-25 | 1982-11-16 | Shell Oil Company | Retort-sterilizable pouch |
| US4387451A (en) * | 1981-06-03 | 1983-06-07 | The United States Of America As Represented By The Secretary Of The Navy | Low frequency nonresonant acoustic projector |
| JPS5871904A (en) * | 1981-10-23 | 1983-04-28 | Asahi Chem Ind Co Ltd | Improved linear medium-to-low density polyethylene composition |
| US4375531A (en) * | 1982-01-11 | 1983-03-01 | Northern Petrochemical Company | High impact visbroken polymeric blends |
-
1984
- 1984-12-19 US US06/683,748 patent/US4578430A/en not_active Expired - Lifetime
-
1985
- 1985-12-17 NZ NZ214593A patent/NZ214593A/en unknown
- 1985-12-18 CA CA000497941A patent/CA1256245A/en not_active Expired
- 1985-12-18 DE DE8585202103T patent/DE3575934D1/en not_active Expired - Lifetime
- 1985-12-18 KR KR1019850009556A patent/KR930005820B1/en not_active IP Right Cessation
- 1985-12-18 PT PT81706A patent/PT81706B/en not_active IP Right Cessation
- 1985-12-18 BR BR8506362A patent/BR8506362A/en unknown
- 1985-12-18 IN IN1077/DEL/85A patent/IN165809B/en unknown
- 1985-12-18 AT AT85202103T patent/ATE50269T1/en not_active IP Right Cessation
- 1985-12-18 AU AU51417/85A patent/AU577432B2/en not_active Ceased
- 1985-12-18 EP EP85202103A patent/EP0185434B1/en not_active Expired - Lifetime
- 1985-12-18 NO NO855125A patent/NO165844C/en unknown
- 1985-12-18 ES ES550107A patent/ES8702445A1/en not_active Expired
- 1985-12-19 JP JP60284540A patent/JPH0657728B2/en not_active Expired - Fee Related
- 1985-12-19 CN CN85109671.9A patent/CN1003789B/en not_active Expired
- 1985-12-19 AR AR85302651A patent/AR242597A1/en active
- 1985-12-19 ZA ZA859682A patent/ZA859682B/en unknown
-
1990
- 1990-07-19 HK HK545/90A patent/HK54590A/en not_active IP Right Cessation
Also Published As
| Publication number | Publication date |
|---|---|
| ES8702445A1 (en) | 1986-12-16 |
| BR8506362A (en) | 1986-09-02 |
| ZA859682B (en) | 1986-08-27 |
| US4578430A (en) | 1986-03-25 |
| CN1003789B (en) | 1989-04-05 |
| AU577432B2 (en) | 1988-09-22 |
| AR242597A1 (en) | 1993-04-30 |
| KR930005820B1 (en) | 1993-06-25 |
| AU5141785A (en) | 1986-06-26 |
| NO855125L (en) | 1986-06-20 |
| PT81706A (en) | 1986-01-01 |
| EP0185434A2 (en) | 1986-06-25 |
| ES550107A0 (en) | 1986-12-16 |
| IN165809B (en) | 1990-01-13 |
| JPS61190510A (en) | 1986-08-25 |
| NO165844B (en) | 1991-01-07 |
| CN85109671A (en) | 1986-10-01 |
| ATE50269T1 (en) | 1990-02-15 |
| KR860004928A (en) | 1986-07-16 |
| EP0185434B1 (en) | 1990-02-07 |
| JPH0657728B2 (en) | 1994-08-03 |
| HK54590A (en) | 1990-07-27 |
| NZ214593A (en) | 1989-01-06 |
| EP0185434A3 (en) | 1986-12-10 |
| PT81706B (en) | 1987-11-30 |
| NO165844C (en) | 1991-04-17 |
| DE3575934D1 (en) | 1990-03-15 |
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