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Extrusion agent based on a heterogeneous pvdf

A heterogeneous, polyolefin technology, applied in the field of processing aids, which can solve the problems of large quantities, processing aids that are not very effective, and cannot significantly reduce extrusion defects

Active Publication Date: 2012-01-11
ARKEMA FRANCE SA
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, the addition of fillers has a tendency to promote the appearance of surface defects
In this case, the processing aids proposed in the prior art are not very effective, that is, they do not significantly reduce extrusion defects or need to be added in larger amounts than the processing aids described in the present application

Method used

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  • Extrusion agent based on a heterogeneous pvdf
  • Extrusion agent based on a heterogeneous pvdf
  • Extrusion agent based on a heterogeneous pvdf

Examples

Experimental program
Comparison scheme
Effect test

example

[0032] Homogeneous PVDF comprising 90% by weight of VDF and 10% by weight of HFP (4.53 mol%) has a melting point of 147°C. The melting point (determined by DSC, ASTM D3418) of the heterogeneous copolymer with the same total HFP content is between 156.6 and 172°C, preferably between 159.8 and 172°C, more preferably between 162.8 and 172°C, Even more preferably between 165.7 and 172°C. The MP of a homogeneous copolymer comprising the same total HFP content is about 148°C.

[0033] A preferred heterogeneous PVDF is a VDF-HFP copolymer comprising 88 to 92% by weight of VDF and 8 to 12% by weight of HFP, with a melting point MP between 160 and 172°C, e.g. example section).

[0034] Heterogeneous PVDF is prepared by polymerization in a dispersed aqueous medium (emulsion or suspension). The aqueous emulsion polymerization is carried out in the presence of at least one surfactant (emulsifier) ​​selected from conventional surfactants. For example, the surfactant can be C 6 f 13 C...

example 1

[0042] Example 1 illustrating the first method: VDF / C 2 F 3 Cl heterogeneous copolymer (12% by weight of C 2 F 3 Cl)

[0043] Introduce the following into a 60-liter autoclave: 40 liters of deionized water, 40 grams of formula C 6 f 13 C 2 h 4 SO 3 K's emulsifier, 4 grams of sodium pyrophosphate, 4 grams of potassium persulfate and 500 grams of paraffin wax that melts between 54 and 56 °C. The temperature was adjusted to 80 °C, the reactor was cleaned under vacuum, 50 g of acetone and 600 g of C were introduced 2 f 3 Cl and allow the pressure of the VDF to be 90 bar. When the pressure drop reached 3 bar, VDF was introduced steadily so that the pressure was maintained at 90 bar. Then with 0.3 g C 2 f 3 The ratio of Cl / l g VDF introduced into C 2 f 3 Cl, where the introduction of VDF kept the pressure at 90 bar. After adding 5.46 kg VDF and 1.64 kg C 2 f 3 After Cl, stop C 2 f 3 Cl was fed and 400 g of acetone and 1 g of potassium persulfate we...

example 2

[0050] Example 2 illustrating the second method: VDF / HFP heterogeneous copolymer (10% by weight of HFP)

[0051] The conditions of the preceding Example 1 were repeated, but with the presence of 1.4 kg of TCFM and an initial content of 0.05% by weight of IPP relative to the initial VDF charge. The viscosity of heterogeneous PVDF is 15.4kP (230°C, 100 seconds -1 ) and a melting point of 163-168°C.

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Abstract

The invention relates to an extrusion agent comprising: at least one heterogeneous PVDF (A), in other words a copolymer of VDF and at least one comonomer of VDF, comprising by weight at least 50%, advantageously at least 75%, of VDF which has a melting point Tm (expressed in DEG C) larger than 172-549 m, preferably larger than 1.1 (172-549 m), where m denotes the overall molar percentage of comonomer(s); and at least one interface agent (B), which are optionally diluted in a polyolefin (C). The heterogeneous PVDF preferably has a Tm of between 160 and 172 DEG C. Advantageously it is also a VDF-HFP copolymer containing, by weight, from 88% to 92% of VDF and from 8% to 12% of HFP. The extrusion agent is used to reduce or eliminate the surface defects which arise during the extrusion of a thermoplastic resin (D). This resin may be a polyolefin, a styrenic resin, a polyester or a PVC. Optionally it may also be filled, i.e., may contain dispersed organic or inorganic particles.

Description

technical field [0001] The present invention relates to a processing aid, that is, an additive that reduces or eliminates surface defects that occur when thermoplastic resins are extruded. The processing aid comprises at least one heterogeneous PVDF (A) and at least one surfactant (B), optionally diluted in a polyolefin (C )middle. Background technique [0002] During the extrusion of thermoplastic resins, especially polyolefins, especially in the form of films, irregular flow can occur at the exit of the extruder die, leading to surface defects and sometimes mechanical and / or or degradation of optical performance. This phenomenon occurs in particular when the critical shear rate is exceeded. Below this critical rate, the extrudate is smooth, while above this rate, surface defects are observed. These defects (referred to as "melt fractures") exist in many forms. At shear rates slightly above this critical rate, the films obtained by extrusion blow molding lose their tra...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C08L23/00C08K5/00C08L27/16
CPCC08K5/0008C08L27/16C08L2205/06C08K5/32C08L23/0815C08K5/06C08L23/00C08K5/10C08L71/02C08K5/02C08L2666/02C08L2666/04C08L2666/14
Inventor 安东尼·邦尼特约翰·拉法格弗朗索瓦·博米
Owner ARKEMA FRANCE SA