CA1077183A - Mixing particulate additives into thermoplastics polymers - Google Patents
Mixing particulate additives into thermoplastics polymersInfo
- Publication number
- CA1077183A CA1077183A CA244,972A CA244972A CA1077183A CA 1077183 A CA1077183 A CA 1077183A CA 244972 A CA244972 A CA 244972A CA 1077183 A CA1077183 A CA 1077183A
- Authority
- CA
- Canada
- Prior art keywords
- mixer
- polymer
- carbon black
- blades
- rotary blade
- 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
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29B—PREPARATION OR PRETREATMENT OF THE MATERIAL TO BE SHAPED; MAKING GRANULES OR PREFORMS; RECOVERY OF PLASTICS OR OTHER CONSTITUENTS OF WASTE MATERIAL CONTAINING PLASTICS
- B29B7/00—Mixing; Kneading
- B29B7/80—Component parts, details or accessories; Auxiliary operations
- B29B7/88—Adding charges, i.e. additives
- B29B7/885—Adding charges, i.e. additives with means for treating, e.g. milling, the charges
-
- 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
-
- 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
- C08J3/203—Solid polymers with solid and/or liquid additives
Landscapes
- Chemical & Material Sciences (AREA)
- Health & Medical Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Medicinal Chemistry (AREA)
- Polymers & Plastics (AREA)
- Organic Chemistry (AREA)
- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Processes Of Treating Macromolecular Substances (AREA)
- Processing And Handling Of Plastics And Other Materials For Molding In General (AREA)
- Compositions Of Macromolecular Compounds (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE:
Particulate additives such as carbon black and thermoplastics in a powdered form are mixed by first charging them to a rotary blade mixer and then charging the mixture obtained to an internal mixer. In this way the mixing cycle Or the internal mixer is drastically shortened with no adverse effect on the quality of the blend obtained. The process also permits a wider range of polymers to be mixed in an internal mixer and avoids the generation of steam and consequent loss of additive normally associated with carton black mixing operations carried out in Banbury mixers.
Particulate additives such as carbon black and thermoplastics in a powdered form are mixed by first charging them to a rotary blade mixer and then charging the mixture obtained to an internal mixer. In this way the mixing cycle Or the internal mixer is drastically shortened with no adverse effect on the quality of the blend obtained. The process also permits a wider range of polymers to be mixed in an internal mixer and avoids the generation of steam and consequent loss of additive normally associated with carton black mixing operations carried out in Banbury mixers.
Description
Po 27589 1~77183 ~his invention relates to mixing particulate additives with thermoplastics polymers such as low density pol~ethylene which are made by proce~ses which produce polymer in a molten state. The invention also relates to compositions comprising additives dispersed in thermoplastics polgmers of this type.
Polymers which are produced in the molten state are conventionally converted into solid granules for ease of handling and the granules have to be subjected to further melting if it is desired to mix solid additives into the polymer and obtain a highly uniform composition. Unfortunately solid additives tend to agglomerate into lumps when mixed with molten polymer and unless the lumps are broken down during the mixing operation~ the lumps will be present in the final composition. For example, compositions comprising lumps of solid additive are obtained if mixing is carried out using a conventional screw extruder. ~his happens because a conventional screw extruder melts the polymer by means of an external heat source such as a steam jacket or an ~ electrical heating element and as a result the charge ; of polymer and additive quickly becomes too fluid for the extruder to be able to subject the charge to shear forces large enough to break down the lumps of additive.
Polymers which are produced in the molten state are conventionally converted into solid granules for ease of handling and the granules have to be subjected to further melting if it is desired to mix solid additives into the polymer and obtain a highly uniform composition. Unfortunately solid additives tend to agglomerate into lumps when mixed with molten polymer and unless the lumps are broken down during the mixing operation~ the lumps will be present in the final composition. For example, compositions comprising lumps of solid additive are obtained if mixing is carried out using a conventional screw extruder. ~his happens because a conventional screw extruder melts the polymer by means of an external heat source such as a steam jacket or an ~ electrical heating element and as a result the charge ; of polymer and additive quickly becomes too fluid for the extruder to be able to subject the charge to shear forces large enough to break down the lumps of additive.
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Po 27~89 ~07~183 Xighly lln;form masterbatch compo~itions comprising for example carbon black and low densit~
pol~ethylene which are sufficiently uniform ~or use in m~ki~g high quality films or electrical insulation can be made using an internal mixer provided certain steps are taken. An internal mixer ~8 a mixer which melts the polymer by ~ing heat generated internally of the polymer as a result of mechan cal work done on the pol~mer b~ the mixer. ~he ~an~uIs*mixer describ~d on pages 411 to 413 of the book "Polythene"
(2nd Edition) edited by A Renfrew and P Morgan and published by Iliffe is a tgpical example of an iaternal mixer. However even an internal mixer will not produce a highly uDiform composition unless unwelcome step~
are taken to increase the heat capaci~-of the charge in the mixer. ~his is necessary because the shearing action of the mixer is only sufficient to break down agglomerates of additive when the temperature of the ` charBe i8 either at or a little above the melting point of the polymer. Clearl~ increasing the heat capacity of the charge increa6es the time taken for the charge to heat through this temperature zone and consequently the charge is sub~ected to bhe sheari3g action of the mixer for a greater period of time.
In practice the heat capacit~ is raised by introducing *Trade mark
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. . . . -..
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Po 27~89 ~07~183 Xighly lln;form masterbatch compo~itions comprising for example carbon black and low densit~
pol~ethylene which are sufficiently uniform ~or use in m~ki~g high quality films or electrical insulation can be made using an internal mixer provided certain steps are taken. An internal mixer ~8 a mixer which melts the polymer by ~ing heat generated internally of the polymer as a result of mechan cal work done on the pol~mer b~ the mixer. ~he ~an~uIs*mixer describ~d on pages 411 to 413 of the book "Polythene"
(2nd Edition) edited by A Renfrew and P Morgan and published by Iliffe is a tgpical example of an iaternal mixer. However even an internal mixer will not produce a highly uDiform composition unless unwelcome step~
are taken to increase the heat capaci~-of the charge in the mixer. ~his is necessary because the shearing action of the mixer is only sufficient to break down agglomerates of additive when the temperature of the ` charBe i8 either at or a little above the melting point of the polymer. Clearl~ increasing the heat capacity of the charge increa6es the time taken for the charge to heat through this temperature zone and consequently the charge is sub~ected to bhe sheari3g action of the mixer for a greater period of time.
In practice the heat capacit~ is raised by introducing *Trade mark
- 3 -'f~3 ' :
Po 27589 1~7~1-83 water into the charge usually by using wet additives.
Unfortunatley the use of charges containing water increases the dwell time of the charge in the mixer so that internal mixing operations become bottlenecks in commercial operations. Moreover the presence of water in the charge leads to the generation of steam which escapes from the mixer under pressure and is a potential hazard, a source of corrosion and also a means by which additive can be carried out of the mixer to pollute the atmosphere. It is therefore an object of this invention to speed up internal mixing operations and to avoid the need to use water in internal mixing operations thus leading to safer and oleaner processes.
~ A further disadvantage of internal mixing proceæses is that even when wet additives are used, the internal mixer can only be used with charges which contain polymers which melt to give highly viscous i melts. For example internal mixers are only used commercially to mix charges comprising low density polyethylene having a melt flow index of less than about 15 to 20 g/10 minutes (as measured according to British Standard 2782: Part 1/105C/1970 using a 2.16 kg load). It is a further obaect of this invention to increase the range of polymers which can be usefully subaected to internal mi2ing proce~ses.
Po 27589 1~7~1-83 water into the charge usually by using wet additives.
Unfortunatley the use of charges containing water increases the dwell time of the charge in the mixer so that internal mixing operations become bottlenecks in commercial operations. Moreover the presence of water in the charge leads to the generation of steam which escapes from the mixer under pressure and is a potential hazard, a source of corrosion and also a means by which additive can be carried out of the mixer to pollute the atmosphere. It is therefore an object of this invention to speed up internal mixing operations and to avoid the need to use water in internal mixing operations thus leading to safer and oleaner processes.
~ A further disadvantage of internal mixing proceæses is that even when wet additives are used, the internal mixer can only be used with charges which contain polymers which melt to give highly viscous i melts. For example internal mixers are only used commercially to mix charges comprising low density polyethylene having a melt flow index of less than about 15 to 20 g/10 minutes (as measured according to British Standard 2782: Part 1/105C/1970 using a 2.16 kg load). It is a further obaect of this invention to increase the range of polymers which can be usefully subaected to internal mi2ing proce~ses.
- 4 -,': ~ ' ' :~
Po 27589 :1~77183 This invention provides a quicker method for mixLng particulate additives into a thermoplastics polymer which has been made by a process which produces polymer in a molten state, the method compri~ing a) subjecting the polgmer in the form of a powder 95/0 by weight of which is capable of passing through a 2,000~m sieve and the . particulate additive to the mixing action of a rotary blade mixer in which the blades 10 . are rotating at a speed su~ficient to fluidise the mixture and then b) subjecting the mixture produced in the rotary blade mixer to the further mixiDg action of an internal mixer.
The use of this method to mix carbon black into low density polyethylene can result in a ten fold reduction in the time taken by the internal mixer to produce masterbatch compositions suitable for use in the - manufacture of high quality films and electrical ~:
insulation.
A rotary blade mixer is a mixer such as the Henschel*500 ~M mixer or the R 600 Diosna*mixer both of whichcomprise two or more horizontal blades rotatably : . mounted within a vessel and means to rotate the blades at a speed su~ficient to fluidise particulate material *Trade marks
Po 27589 :1~77183 This invention provides a quicker method for mixLng particulate additives into a thermoplastics polymer which has been made by a process which produces polymer in a molten state, the method compri~ing a) subjecting the polgmer in the form of a powder 95/0 by weight of which is capable of passing through a 2,000~m sieve and the . particulate additive to the mixing action of a rotary blade mixer in which the blades 10 . are rotating at a speed su~ficient to fluidise the mixture and then b) subjecting the mixture produced in the rotary blade mixer to the further mixiDg action of an internal mixer.
The use of this method to mix carbon black into low density polyethylene can result in a ten fold reduction in the time taken by the internal mixer to produce masterbatch compositions suitable for use in the - manufacture of high quality films and electrical ~:
insulation.
A rotary blade mixer is a mixer such as the Henschel*500 ~M mixer or the R 600 Diosna*mixer both of whichcomprise two or more horizontal blades rotatably : . mounted within a vessel and means to rotate the blades at a speed su~ficient to fluidise particulate material *Trade marks
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Po 27589 charged to the ve~sel. Preferably the sum of the linear speeds of the tips of the blades ~hould not be less than 1,000 cmJsecond which means that the two blades of the Henschel mixer should be rotated to give a tip speed of at least 500cms/sec for each blade and the four blades of the Diosna mixer should be rotated to give a tip speed of 250 cm/sec for each blade. ~he best results are usually obtained when the sum of the tip speeds lies in the range 4,000 to 40,000 cm/sec.
The blades of the rotary blade mixer exert a fluidising effect on a charge of particulate material in the vesseI and generate currents within the charge which cause particles of the charge to circulate in directions having a vertical component. During mixing, adjacent particles rub together and at least in the case of particulate low density polyethylene, there is a tendency for solid particles of additive to adhere to the surface of the pol~ethylene partic1es.
It appesrE that when the mixture i8 transferred to the internal mixer for further mixing, this adherence of the~so1id particles to the polymer partioles is sufficient to prevent the formation of large ~uantities of new agglomerates during the period before the internal mixer begins to melt the polyethylene.
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.
Po 27589 10~7183 ~he polymer charged to the rotary blade mixer will have been ground into a powder 95~o and preferably 99~ by weight of which is capable of passing through a 2,000~m sieve, that is to say a sieve composed of apertures 2,000~m square. Preferably 99~ by weight of the powder should pass through a 1,200~m sieve and preferably not more than 35% by weight of the powder should pass through a 300~ sieve.
~he process of this invention is e~pecially suitable for use with low density polyethylene aDd copolymers of ethylene made by the free radical polymerisation process. ~ow density polyethylene has a density of less than 0.94 g/cm3. Suitable ethylene copolymers include copolymers of ethylene with comonomers such as acrylic or methacrylic acids or their methyl, ethyl or butyl esters or vinyl acetate.
The copolymers usually tolerate much higher levels of additive than the homopolymers and are therefore particularly suitable for masterbatches or for sound ` 20 insulation compositions.
Other polymers which are made by processes producing molten polymer include the various polyamides and polyethylene terephthalate.
; Hitherto internal mixes have failed to produce good dispersions of solid additives in polyeth~lenes , . . .. : ~ :
: . . . .
. . .
. . . . .
.
Po 27589 18~r~1 ~ 3 having melt flow indices above about 15 to 20 g/10 minutes. This has meant that masterbatche~ of low melt flow index have had to be used even with virgin polymer of high melt flow index despite the difficulties of mixing polymers of widely differing melt flow indices. ~he process of this invention allows highly uniform masterbatch compositions to be made from low density polyethylenes or from ethylene copolymers having melt flow indices of from 20 to 250 g/10 mins.
i 10 Accordingly this invention also provides a composition comprising a low density polyethylene or a copolymer of ethylene with an unsaturated acid or ester having a melt flow index of from 20 to 250 and from 10 to sah by weight (based on the weight of the composition) of a solid additive, the composition being sufficiently highly uniform to be used in the manufacture of high quality films or electrical insulation. In particular the composition is capable of being melt mixed with virgin polymer to produce a polymer composition comprising 3% by weight of additive which meets -the requirements for dispersion as set out in ~ritish Standard 3412 of 1966. Although the British Standard refers explicitly to carbon black, the techni~ue described is applicable to all additives capable of being rendered visible under magnification.
Po 27589 1~'77183 The process of this invention may be used with a wide variety of solid additives including carbon black and the pigments "Nigrosine" and l~ophthnlocyanine blue which are difficult to disperse. Other additives include talc~ silica,titanium dioxide and butyl rubber. Additives such as antioxidants, antistatic agents and cross-linking agents may increase the dwell time of the char~e in the internal mixer, but the dwell times are still shorter than can be achieved using the old process.
The invention is further illustrated by the following examples of which Examples A and B are comparative.
The arithmetic mean diameters of the carbon blacks quoted in the examples were obtained by measurements taken from electron micrographs of the blacks. The surface areas of the carbon blacks were determined by nitrogen absorbtion using the method of Brunauer-Emett-~eller. ~he densities of the polyethylenes quoted were measured according to British Standard 3412 of 1966.
Examples A and B
44 kg of water and 55 kg of particles of carbon black having a surface area and arithmetic mean diameter as specified in the ~able were stirred together :.
, . " . ' , . '' ' . ' .
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-` Po 27589 1~77~83 in a 'U'-trough using a rotating paddle until the particles of carbon black had become thoroughly wet.
The wet carbon black and 11~kg of polyethylene having a density and melt flow index a~ specified in the ~able were charged to a Banbury mQxer. ~he polyethylene was in the form of cubic granules having a volume of 30 mm3. The mixer was operated for 25 minutes and produced a masterbatch composition compri ing approximately 3~/o by weight of carbon black and 70% by weight of pol~ethylene. Steam a~d ~- carbon black were seen to escape from the mixer during operation of the mixing process.
; ~he masterbatch composition obtained was capable ~; of being diluted to a composition of 3% by weight carbon black by mixing it with a further quantity of the same polyethylene granules using a conventional screw extruder of the kind used in wire coating.`
- The diluted composition had a highly uniform dispersion of carbon black which met the requirements of Briti~h Standard ~412.
Examples 1 to 4 55 kg of particles of carbon black having surface areas and arithmetic mean diameters as specified in the ~able were charged to a Henschel rotary blade mixer along with 110 kg of pol~ethylenes having densities , ... . ~ . , ~, :..
.
1077~83 Po 27589 .
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` 10~P71 8 3 pO 27589 and melt flow indices as specified in the ~able. ~he polyethylene was in the form of a powder 9~h by weight of which passed through an 850~m sieve and 4~ of which was retained by a 300~m sieve.
Both blades of the Henschel mixer ~ere rotated for 1 minute so as to give the tip of each blade a ~ linear speed of 6979 cm/sec and then the blades were ; rotated at a faster speed so as to give the tip of each blade a linear speed of 1~912 cm/sec. ~he blades were rotated at this faster speed until the temperature of the charge had reached 60C which occurred within 5 to 10 minutes although the actual time taken varied unpredictably within this range.
The mixture from the rotary blade mixer was charged to the same Banbury mixer as had been used for Examples A and B and the time taken for the Banbury mixer to produce a masterbatch composition which was at least as uniform as those obtained in Examples A and B was determined. ~hese tlmes are shown in the Table.
~he absence of a wet additive in the charge not only avoided the generation of steam but only led to a reduction in the volume of the charge which in effect means that an extra amount of charge could have been fed to the Banbury mixer if desired and this would of `.~
- '12 -- Po 27589 10771~
course increase ~he capacity of the mixer leading to a further reduction in the bottleneck effect of internal mixing processes.
~ es 5 to 8 ~he procedure of Examples 1 to 4 was repeated except the proportion of carbon black charged to the rotary blade mixer was adjusted so as to produce final masterbatch compositions containing 1~h, 25%
or 40~ by weight of carbon black as shown in the ~able.
Example 9 The procedure of Examples 1 to 4 was repeated using a polyethylene containing 3.~h by weight of the antioxidant 2,2'-methylene bis ~6~-methyl cyclohexyl) 4-methyl phenol]. As is shown in ~able 1 the presence of the antioxidant necessitated à slightl~
longer period of internal mixing as compared with Example 1.
Example 10 Example 1 was repeated using a copolymer of : 20 ethylene and 18% by weight of vinyl acetate instead of the polyethylene used in Example 1. ~he copolymer had a melt flow index of 10.
The masterbatch composition obtained could be diluted with virgin polyethylene as in Example A or with virgin ethylene/vinyl acetate copolymer of melt '` ' .` ,'-. ' :
. ' .
`" Po 275~9 ~(~77~83 flow index 10. In both cases it is possible to obtaincompositions comprising 3% by weight of carbon black which are at least as uniform as those obtained in Examples A and B.
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Po 27589 charged to the ve~sel. Preferably the sum of the linear speeds of the tips of the blades ~hould not be less than 1,000 cmJsecond which means that the two blades of the Henschel mixer should be rotated to give a tip speed of at least 500cms/sec for each blade and the four blades of the Diosna mixer should be rotated to give a tip speed of 250 cm/sec for each blade. ~he best results are usually obtained when the sum of the tip speeds lies in the range 4,000 to 40,000 cm/sec.
The blades of the rotary blade mixer exert a fluidising effect on a charge of particulate material in the vesseI and generate currents within the charge which cause particles of the charge to circulate in directions having a vertical component. During mixing, adjacent particles rub together and at least in the case of particulate low density polyethylene, there is a tendency for solid particles of additive to adhere to the surface of the pol~ethylene partic1es.
It appesrE that when the mixture i8 transferred to the internal mixer for further mixing, this adherence of the~so1id particles to the polymer partioles is sufficient to prevent the formation of large ~uantities of new agglomerates during the period before the internal mixer begins to melt the polyethylene.
.
.. . .
. ' ' ,: . ;: : -..
.
Po 27589 10~7183 ~he polymer charged to the rotary blade mixer will have been ground into a powder 95~o and preferably 99~ by weight of which is capable of passing through a 2,000~m sieve, that is to say a sieve composed of apertures 2,000~m square. Preferably 99~ by weight of the powder should pass through a 1,200~m sieve and preferably not more than 35% by weight of the powder should pass through a 300~ sieve.
~he process of this invention is e~pecially suitable for use with low density polyethylene aDd copolymers of ethylene made by the free radical polymerisation process. ~ow density polyethylene has a density of less than 0.94 g/cm3. Suitable ethylene copolymers include copolymers of ethylene with comonomers such as acrylic or methacrylic acids or their methyl, ethyl or butyl esters or vinyl acetate.
The copolymers usually tolerate much higher levels of additive than the homopolymers and are therefore particularly suitable for masterbatches or for sound ` 20 insulation compositions.
Other polymers which are made by processes producing molten polymer include the various polyamides and polyethylene terephthalate.
; Hitherto internal mixes have failed to produce good dispersions of solid additives in polyeth~lenes , . . .. : ~ :
: . . . .
. . .
. . . . .
.
Po 27589 18~r~1 ~ 3 having melt flow indices above about 15 to 20 g/10 minutes. This has meant that masterbatche~ of low melt flow index have had to be used even with virgin polymer of high melt flow index despite the difficulties of mixing polymers of widely differing melt flow indices. ~he process of this invention allows highly uniform masterbatch compositions to be made from low density polyethylenes or from ethylene copolymers having melt flow indices of from 20 to 250 g/10 mins.
i 10 Accordingly this invention also provides a composition comprising a low density polyethylene or a copolymer of ethylene with an unsaturated acid or ester having a melt flow index of from 20 to 250 and from 10 to sah by weight (based on the weight of the composition) of a solid additive, the composition being sufficiently highly uniform to be used in the manufacture of high quality films or electrical insulation. In particular the composition is capable of being melt mixed with virgin polymer to produce a polymer composition comprising 3% by weight of additive which meets -the requirements for dispersion as set out in ~ritish Standard 3412 of 1966. Although the British Standard refers explicitly to carbon black, the techni~ue described is applicable to all additives capable of being rendered visible under magnification.
Po 27589 1~'77183 The process of this invention may be used with a wide variety of solid additives including carbon black and the pigments "Nigrosine" and l~ophthnlocyanine blue which are difficult to disperse. Other additives include talc~ silica,titanium dioxide and butyl rubber. Additives such as antioxidants, antistatic agents and cross-linking agents may increase the dwell time of the char~e in the internal mixer, but the dwell times are still shorter than can be achieved using the old process.
The invention is further illustrated by the following examples of which Examples A and B are comparative.
The arithmetic mean diameters of the carbon blacks quoted in the examples were obtained by measurements taken from electron micrographs of the blacks. The surface areas of the carbon blacks were determined by nitrogen absorbtion using the method of Brunauer-Emett-~eller. ~he densities of the polyethylenes quoted were measured according to British Standard 3412 of 1966.
Examples A and B
44 kg of water and 55 kg of particles of carbon black having a surface area and arithmetic mean diameter as specified in the ~able were stirred together :.
, . " . ' , . '' ' . ' .
, ~ .: : -: . . ..
.
-` Po 27589 1~77~83 in a 'U'-trough using a rotating paddle until the particles of carbon black had become thoroughly wet.
The wet carbon black and 11~kg of polyethylene having a density and melt flow index a~ specified in the ~able were charged to a Banbury mQxer. ~he polyethylene was in the form of cubic granules having a volume of 30 mm3. The mixer was operated for 25 minutes and produced a masterbatch composition compri ing approximately 3~/o by weight of carbon black and 70% by weight of pol~ethylene. Steam a~d ~- carbon black were seen to escape from the mixer during operation of the mixing process.
; ~he masterbatch composition obtained was capable ~; of being diluted to a composition of 3% by weight carbon black by mixing it with a further quantity of the same polyethylene granules using a conventional screw extruder of the kind used in wire coating.`
- The diluted composition had a highly uniform dispersion of carbon black which met the requirements of Briti~h Standard ~412.
Examples 1 to 4 55 kg of particles of carbon black having surface areas and arithmetic mean diameters as specified in the ~able were charged to a Henschel rotary blade mixer along with 110 kg of pol~ethylenes having densities , ... . ~ . , ~, :..
.
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` 10~P71 8 3 pO 27589 and melt flow indices as specified in the ~able. ~he polyethylene was in the form of a powder 9~h by weight of which passed through an 850~m sieve and 4~ of which was retained by a 300~m sieve.
Both blades of the Henschel mixer ~ere rotated for 1 minute so as to give the tip of each blade a ~ linear speed of 6979 cm/sec and then the blades were ; rotated at a faster speed so as to give the tip of each blade a linear speed of 1~912 cm/sec. ~he blades were rotated at this faster speed until the temperature of the charge had reached 60C which occurred within 5 to 10 minutes although the actual time taken varied unpredictably within this range.
The mixture from the rotary blade mixer was charged to the same Banbury mixer as had been used for Examples A and B and the time taken for the Banbury mixer to produce a masterbatch composition which was at least as uniform as those obtained in Examples A and B was determined. ~hese tlmes are shown in the Table.
~he absence of a wet additive in the charge not only avoided the generation of steam but only led to a reduction in the volume of the charge which in effect means that an extra amount of charge could have been fed to the Banbury mixer if desired and this would of `.~
- '12 -- Po 27589 10771~
course increase ~he capacity of the mixer leading to a further reduction in the bottleneck effect of internal mixing processes.
~ es 5 to 8 ~he procedure of Examples 1 to 4 was repeated except the proportion of carbon black charged to the rotary blade mixer was adjusted so as to produce final masterbatch compositions containing 1~h, 25%
or 40~ by weight of carbon black as shown in the ~able.
Example 9 The procedure of Examples 1 to 4 was repeated using a polyethylene containing 3.~h by weight of the antioxidant 2,2'-methylene bis ~6~-methyl cyclohexyl) 4-methyl phenol]. As is shown in ~able 1 the presence of the antioxidant necessitated à slightl~
longer period of internal mixing as compared with Example 1.
Example 10 Example 1 was repeated using a copolymer of : 20 ethylene and 18% by weight of vinyl acetate instead of the polyethylene used in Example 1. ~he copolymer had a melt flow index of 10.
The masterbatch composition obtained could be diluted with virgin polyethylene as in Example A or with virgin ethylene/vinyl acetate copolymer of melt '` ' .` ,'-. ' :
. ' .
`" Po 275~9 ~(~77~83 flow index 10. In both cases it is possible to obtaincompositions comprising 3% by weight of carbon black which are at least as uniform as those obtained in Examples A and B.
AVC/C0 _14 -
Claims (5)
1. A method for mixing carbon black into a thermo-plastics polymer selected from low density polyethylene and copolymers of ethylene with acrylic or methacrylic acid or their methyl, ethyl or butyl esters or vinyl acetate,said poly-mer having been made by a process which produces polymer in a molten state, the method comprising (a) subjecting the polymer in the form of a powder 95% by weight of which is capable of passing through a 2,000 µm sieve and the carbon black to the mixing action of a rotary blade mixer in which the blades are rotating at a speed sufficient to fluidise the mixture and then (b) subjecting the mixture produced in the rotary blade mixer to the further mixing action of an internal mixer.
2. A method as claimed in Claim 1 wherein the poly-mer is low density polyethylene.
3. A method according to Claim 1 wherein the blades of the rotary blade mixer are rotating such that the sum of the linear speeds of the tips of the blades is not less than 1,000 cm/second.
4. A method according to Claim 3 wherein the sum of the linear speeds of the tips lies in the range 4,000 to 40,000 cm/second.
5. A method according to Claim 1, 2 or 3 wherein 99%
by weight of the polymer powder is capable of passing through a 1,2000 µm sieve.
by weight of the polymer powder is capable of passing through a 1,2000 µm sieve.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB429075A GB1476537A (en) | 1975-01-31 | 1975-01-31 | Mixing particulate additives into thermoplastics polymers |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1077183A true CA1077183A (en) | 1980-05-06 |
Family
ID=9774371
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA244,972A Expired CA1077183A (en) | 1975-01-31 | 1976-01-30 | Mixing particulate additives into thermoplastics polymers |
Country Status (9)
| Country | Link |
|---|---|
| JP (1) | JPS51102034A (en) |
| BE (1) | BE838191A (en) |
| CA (1) | CA1077183A (en) |
| DE (1) | DE2603378A1 (en) |
| ES (1) | ES444785A1 (en) |
| FR (1) | FR2299136A1 (en) |
| GB (1) | GB1476537A (en) |
| IT (1) | IT1054968B (en) |
| NL (1) | NL7600860A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4369267A (en) | 1979-06-01 | 1983-01-18 | Union Carbide Canada Limited | Process for dispersing carbon black in polyethylene |
Families Citing this family (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4687573A (en) * | 1984-08-13 | 1987-08-18 | Pall Corporation | Sorbing apparatus |
| DE3702833A1 (en) * | 1987-01-30 | 1988-08-11 | Peter Julius | METHOD AND DEVICE FOR PRODUCING RUBBER COMPOUNDS |
| US4830641A (en) * | 1987-04-13 | 1989-05-16 | Pall Corporation | Sorbing apparatus |
| DE19807261A1 (en) * | 1998-02-20 | 1999-08-26 | Koever Gmbh & Co Kunststoff Te | Process for making colored plastic powder |
| JP5052764B2 (en) * | 2005-05-24 | 2012-10-17 | 東京インキ株式会社 | Method for producing metallocene linear low density polyethylene resin composition containing nucleating agent |
-
1975
- 1975-01-31 GB GB429075A patent/GB1476537A/en not_active Expired
-
1976
- 1976-01-23 IT IT1953576A patent/IT1054968B/en active
- 1976-01-26 FR FR7601979A patent/FR2299136A1/en active Granted
- 1976-01-28 NL NL7600860A patent/NL7600860A/en not_active Application Discontinuation
- 1976-01-29 DE DE19762603378 patent/DE2603378A1/en not_active Withdrawn
- 1976-01-30 ES ES444785A patent/ES444785A1/en not_active Expired
- 1976-01-30 JP JP921676A patent/JPS51102034A/en active Pending
- 1976-01-30 CA CA244,972A patent/CA1077183A/en not_active Expired
- 1976-02-02 BE BE164027A patent/BE838191A/en not_active IP Right Cessation
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4369267A (en) | 1979-06-01 | 1983-01-18 | Union Carbide Canada Limited | Process for dispersing carbon black in polyethylene |
Also Published As
| Publication number | Publication date |
|---|---|
| AU1047776A (en) | 1977-07-28 |
| FR2299136B1 (en) | 1979-06-29 |
| JPS51102034A (en) | 1976-09-09 |
| NL7600860A (en) | 1976-08-03 |
| GB1476537A (en) | 1977-06-16 |
| BE838191A (en) | 1976-08-02 |
| IT1054968B (en) | 1981-11-30 |
| ES444785A1 (en) | 1977-05-16 |
| DE2603378A1 (en) | 1976-08-05 |
| FR2299136A1 (en) | 1976-08-27 |
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| Date | Code | Title | Description |
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| MKEX | Expiry |