Process for the production of expandable vinyl aromatic polymer granulate having decreased thermal conductivity
AssigneeSynthos S.A.
InventorsFilip Lukasz KONDRATOWICZ, Piotr ROJEK, Marzena MIKOSZEK-OPERCHALSKA, Kamil UTRATA
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Abstract
The invention relates to an extrusion process for the production of expandable vinyl aromatic polymer granulate comprising mixing first and second additives with first and second polymer components, respectively, in dedicated mixers.
Claims21
Extrusion process for the production of expandable vinyl aromatic polymer granulate comprising the steps:
- i) feeding a first polymer component comprising vinyl aromatic polymer into a first mixer;
- ii) feeding a first additive component a) into the first mixer, to produce a first mixture from the first polymer component and the first additive component;
- iii)feeding a second polymer component b) comprising vinyl aromatic polymer into a second mixer;
- iv) feeding a second additive component b) into the second mixer, to produce a second mixture from the second polymer component and the second additive component, wherein the processing conditions in the second mixer are more severe than the processing conditions in the first mixer, by providing higher shear force;
- v) combining the first and second mixtures, to produce a third mixture;
- vi) injecting blowing agent c) into the third mixture, to produce a fourth mixture;
- vii)mixing the fourth mixture;
- and viii) pelletizing the fourth mixture, to obtain the granulate,
- wherein the process comprises an extrusion.
The process of any one of the preceding claims, wherein the temperature in the first mixer is in the range of 100 to 250° C., more preferably 150 to 230° C.
The process of any one of the preceding claims, wherein the second mixer is an extruder or a static mixer, preferably a co-rotating twin screw extruder.
The process of any one of the preceding claims, wherein vi) the injection is into the third mixture, the third mixture being a melt.
The process of any one of the preceding claims, wherein the first additive component a) comprises one or more of
- a1) nucleating agent,
- a2) flame retardant,
- a3) synergist,
- a4) thermal oxidative stabiliser,
- a5) flame retardant thermal stabiliser, and
- a6) dispersion aid.
The process of any one of the preceding claims, wherein the second additive component b) comprises one or more powders.
The process of any one of the preceding claims, wherein the second additive component b) consist of one or both of
- b1) a mineral constituent and
- b2) a carbonaceous constituent,
- preferably wherein the second additive component b) consists of both b1) a mineral constituent and b2) a carbonaceous constituent.
The process of any one of the preceding claims, wherein the vinyl aromatic copolymer is made from styrene and a sterically hindered styrene comonomer (which is preferably p-tert-butylstyrene),
- preferably wherein the styrene-based copolymer comprises 1 to 99 wt. % of p-tert-butylstyrene comonomer, more preferably 1 to 50 wt. % of p-tert-butylstyrene comonomer, in particular 2 to 30 wt. % of p-tert-butylstyrene comonomer, based on the total weight of monomer.
The process according to any one of the preceding claims, wherein the combining v), to produce the third mixture, is of
- a melt of the first mixture with
- a melt of the second mixture from the second mixer, preferably directly from the second mixer.
The process according to any one of the preceding claims, wherein the severe processing conditions in the second mixer comprise a shear rate in a range of from 1/5 s−1 to 1/100 s−1, preferably from 1/10 to 1/80 s−1, more preferably from 1/20 to 1/60 s−1
Expandable vinyl aromatic polymer granulate as obtainable by the process according to any one of the preceding claims.
Dependencies are inferred from the claim text.