Technical Papers Plastics
Kokneader ideal for large throughput of PVC compounds

Kokneader ideal for large throughput of PVC compounds

Techno - commercial information on plastics Industry - News on Plastics Industry - Plastemart.com
 
Kokneader ideal for large throughput of PVC compounds

Kokneader ideal for large throughput of PVC compounds

 
Polyvinyl chloride (PVC), because of its sensitivity to heat and shear stress, is different from all the polymers like polyethylenes, polypropylene, etc. Besides, PVC is compounded with a very large amount of different additives. In fact, 70% of all polymer additives are used only in PVC. PVC compounds are also made under different processing conditions of heat and shear stress.
Before PVC can be made into products, it has to be combined with a range of special additives. The essential additives for all PVC materials are stabilisers and lubricants; in the case of flexible PVC, plasticisers are also incorporated. Rigid PVC is very shear sensitive while flexible PVC containing large amount of plasticizers is much more stable. Other additives which may be used include fillers, processing aids, impact modifiers and pigments. Additives will influence or determine the mechanical properties, light and thermal stability, colour, clarity and electrical properties of the product. The mixing of additives needs to be selected based on type and amount of these additives that are incorporated in PVC polymer to achieve different properties. Once the additives have been selected, they are mixed with the polymer in a process called compounding. The mixers can include batch mixers, continuous mixers, twin-screw compounding extruders or continuous kneaders. One method uses an intensive high-speed mixer that intimately blends all the ingredients. The result is a powder, known as a �dry blend�, which is then fed into the processing equipment. Additives are added in a mixer and first the dryblend is made. Dryblend is either directly processed into the finished products or is first melt blended and pelletized. The goal of dry-blending; the co-mingling of PVC pellets with several types of additives - is to achieve a homogeneous free-flowing powder without a phase change which is then fed into melt compounding equipment. The workhorse machine throughout the history of PVC compounding has been the high-intensity batch. Direct processing of dryblend is typically done for rigid PVC products like pipe & profiles. The dryblend is directly processed on a conical or parallel twin screw extruder into finished products. For direct extrusion of a finished part, there is no need to pelletize the dry-blend, which can be processed using a conical or parallel twin-screw extruder to extrude directly into the finished part. Sheet compounds, depending on the type, may need a pelletizing step first in some cases, especially if a single-screw extruder is used for producing the finished sheet.
Economics plays a greater role in selection of mixing process and its equipments. Buss�s kneader technology and Coperion�s co-rotating twin-screw compounder are found to be ideal for the production of highly filled compounds�both flexible and rigid. For flexible PVC, the mixing equipment is selected based on plasticizer levels like:
  • For formulations with upto 30 parts of liquid plasticizer, a continuous turbo mixer, followed by a co-rotating twin-screw extruder combined with a discharge extruder and a hot die pelletizing system can be used.
  • For formulations with 30-60 parts of liquid, a batch heater mixer with intermediate vessel and agitator, followed by a co-rotating twin-screw extruder combined with a discharge extruder, and a hot-die pelletizing system can be recommended.
  • For formulations with more than 60 parts of liquid, a heater/cooler batch mixer combination for preparation and dispersion of dry-blend, followed by a co-rotating twin-screw extruder combined with a discharge extruder and a hot-die pelletizing system can be used
The key factors in determining the technology to be used should be based on quality requirements, including output rate, temperature control, mixing efficiency and investment cost. Temperature control is a key issue, since PVC has a temperature memory. The lower the processing temperature used in the compounding step, the lower the temperature for moulding or extruding the material, thus giving better flexibility and temperature stability. Quality is typically linked to dispersion of the components during premixing and melt compounding. Absence of gels on the extruded surface and improved processability are key parameters of good mixing.
Farrel Continuous Mixer (FMC) is regarded by many in the industry as the most effective compounder for all variants of PVC, but especially in the production of semi-rigid and rigid PVC compounds. Continuous Mixer or Combi machine of Coperion which has twin screw along with single screw for delivering the melt under pressure to pelletizer is now widely used in PVC compounding. Coperion has now developed the combi machines to incorporate almost 85% of filler in PVC.
For a high throughput vinyl compounding applications - such as at suppliers manufacturing pelletized compounds for the commercial market - the kneader technology is very effective for up to 4,600 kg/hr.
 
 
 
  Back to Articles

Previous Article

Next Article

JIRIKOVA VERONIKA made a post.
11-Oct-23

Potřebujete finanční pomoc? Jste podnikatel? Jste v obtížné finanční situaci? Nebo potřebujete peníze, abyste mohli začít svůj vlastní podnik? nebo placení účtů nebo placení za dům, auto? Zájem o online finanční pomoc? Potřebujete důvěryhodný soukromý věřitel s osvědčenými zkušenostmi? Pokud ano, kontaktujte mě e-mailem: Veronikajirikova10@gmail.com whatsapp.....+420704207735

Tyrner Jan made a post.
01-Oct-23

Nabízíme nejrychlejší půjčky. Žádat můžete od 30 000 Kč do 500 000 000 Kč. Splátky si můžete naplánovat na několik měsíců nebo až na 30 let. Vaši žádost zpracujeme a schválíme téměř okamžitě. Peníze vyplácíme v den podpisu smlouvy. Vše vyřídíte z domova, aniž byste museli chodit do kanceláře. Pro více informací nás kontaktujte emailem. E-mail: tyrnerjan75@gmail.com

Andre Gorsage made a post.
25-Oct-21

Wow, Thanks a lot guys for referring D e nnis ... I contacted him because I had a ba d cre dit sc ore of 490 and he fixed it is a short period of time at an aff ordable rate he raised it to 820 ... I am so happy and thankful for what he did for me... DENNISDFIXER at gm ail. com or +1 9 1 7 7 2 2 6 9 1 3 if you need his servi ces.

monica coffman made a post.
29-Aug-21

Earlier this year I had a really bad c r e d I t and also debts hovering around until I got in contact with Dennis Walker, I must say he is really the best I have come across on what he does which was clearing out my debts and raising my score up to 830 from 490..do well to write him if ever in need of such job.. dennisdfixer at g m a i l . c o m

Paul Brandon made a post.
03-Aug-21

Have you been looking for who will get the job done? without excuses or unplanned occurrences? Get in touch with Dennis Walker now, the only genuine one I have come across. If you are needing your score increased, BK removal etc then reach him on dennisdfixer at gmail dot com or nine one seven. Seven two two. Six nine one three..

Kenneth Amoah made a post.
19-Jan-19

Dear Sir, I am contacting you in regards of the gold business relationship which i would like us to work together to accomplish. Our family are into gold mining and we are direct owner of Alluvial Gold Dust/Gold Bar which We have for sale and we are looking for serious partners/buyers who have interest in punching our, AU GOLD-DUST/BAR and our family are willing to work with you if you are interested in doing business with us. If you can connect us to buyers we are going to pay you good commission per any kilo that your buyer purchase from our seller. We would also like to meet you in person, so we can negotiate and share better ways on how we can finalize the transaction. I am looking forward in reading from you, hope in getting in good relationship with you. MY PRIVATE EMAIL: kofogahanagold@yahoo.com kofogahanagold@yahoo.com kofogahanagold@yahoo.com Sincerely Yours. (For the family). Available at the moment: Commodity: Au Gold Bars Weight:Before And 1kg Bars Origin: Ghana Quantity In Stock: 2 Metric Tons Tranches: Trail Order 1,000kg Type:Au Gold Bars Purity.Finess: Based On 94% Quanlity: 22+ Carat Price: $3,2000 Per Kg Product History: Clean,Clear No Liens And Non-Criminal Origin Subsequent Supply Based On Buyer's Capacity Point Of Assay: Any Oof The Recognised Government Refineries Or As May Be Agreed SUPPLY OF AU GOLD DUST‏/BAR

Uxokoro made a post.
19-Sep-17

Inquiry on purchase of Virgin raw materials homo pp HPIG110 and HDPE.

COMMENTS

0

*

Email Id Required.

Email Id Not Valid.

*

Mobile Required.

*

Name Required.

*

Please enter Company Name.

*

Please Select Country.

Email ID and Mobile Number are kept private and will not be shown publicly.
*

Message Required.

Click to Change image  Refresh Captcha
Reclamax single step plastic recycling machine

Reclamax single step plastic recycling machine