DD146956A1 - DISPOSABLE THERMOPLASTIC MOLDING - Google Patents

Abstract

The invention relates to foamable thermoplastic molding compositions, in particular for the production of foamed moldings and semi-finished products, such as full and hollow profiles and plates in any shape and dimensions, in the extrusion process. The object of the invention is to produce foamable thermoplastic molding compositions based on VC polymers which have a flowability required for good foamability and which do not contain any modifiers and / or processing aids which reduce heat distortion resistance. The object is achieved according to the invention by adding a polymer mixture consisting of a) 50 to 95% by weight, preferably 70 to 90% by weight, suspension PVC having a K value of 60 to 70, b) 5 to 40% by weight T., preferably 10 to 30 wt. T., An emulsion PVC having a K value of 60 to 75, the emulsion method using predominantly anionic emulsifiers, before and / or after the polymerization of small amounts of nonionic emulsifiers and c) 1 to 20 parts by weight, preferably 5 to 10 parts by weight, of a microsuspension PVC having a K value of 60 to 70 is used, the emulsion PVC and the suspension -PVC have the same high Schuettdichte. The total emulsifier content of the emulsion PVC is 1 to 4%.

Description

21,687

-Λ-

VEB CHEMIEKOMBINAT BIT (EEHi ¹ ELD., Bitter field, 9.11.19 '

2016

Expandable thermoplastic molding compounds

Field of application of the invention

The invention relates to foamable thermoplastic Porramassen, in particular for the production of foamed moldings and semi-finished products, such as. B. solid and hollow profiles and Platten.in any shape and dimensions, in the extrusion process.

Characteristic of the known technical solutions

It is known to produce molded parts and semi-finished products from foamed plastics using chemical or physical blowing agents in the extrusion process. It is well known from the prior art that I ⁵ VO can not be satisfactorily foamed even when using low KY / erten, ie that it is not possible to obtain foamed PVC products that significantly

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Lower density than the starting material and have a uniform pore structure (DD-PS 92 318 and DE-OS 1 965 341).

To improve the foamability of PVC, it is therefore customary to add to the PVG certain additives, which may have both monomeric and polymeric character. Thus, it has long been known to use monomer plasticizer containing vinyl chloride homopolymers (Plastiques Modernes et Elastomeres (1970) 4, p 103), which are partially crosslinkable (DE-OS 1,900,413). Although these molding compounds have favorable rheological properties, but the products produced therefrom have no rigidity, but only moderate strength properties and a greatly reduced heat resistance.

It is also known, instead of vinyl chloride homopolymers vinyl chloride copolymers with small amounts of .unsaturated compounds such as vinyl acetate, propylene or vinylidene chloride, use (DE-OS 1,694,439 »DE-OS 2 000 039 and DE-AS 1 I70 614) , However, these products do not have improved processing and utility properties. The bulk densities are often still too high (DE-OS 2 143 377). In another method, the use of polyethylene to improve the foamability of PVC is described (D ^ -OS 2 653 578).

Due to their incompatibility with the PVG, however, the amounts of PE required to achieve the desired effect lead to the appearance of exudation which worsens the appearance and the surface quality of the molded parts.

In general, therefore, it is customary to give the PVC greater proportions of certain, more or less compatible, modifiers, e.g. Ethylene - vinyl acetate - copolymers, chlorinated polyethylene, styrene-acrylonitrile copolymers, acrylonitrile-butadiene-styrene terpolymers,

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Polymethacrylates and the like (DD-PS 128 047, DS-OS 1 629 373, DE-AS 1 694 709, DS-OS 1 965 341 and DB-OS 2 249 435).

Such additives improve the processing properties and, in most cases, give foamed products with low bulk density, uniform pore structure and good surface finish. However, they impair the heat resistance at elevated temperatures, whereby the use value is considerably reduced. In addition, the modified VC polymer compositions have a high cost price.

Furthermore, satisfactory foamable PVC molding compositions are prepared by using mixtures of any suspension or emulsion PVG types with specially polymerized PVC, which additionally contain the usual 2 / Todifiziermittel (DE-OS 2,143,377). However, it has been shown that even such products do not meet the practical requirements, because their foaming ability is insufficient and their rheological properties vary depending on the particular type of PVC used. All of these known processes have the disadvantage that the addition of modifiers and processing aids in particular the heat resistance is significantly reduced and the molding materials manufactured at an increased cost v / earth.

Object of the invention

The aim of the invention is to provide foamable thermoplastic molding compositions based on VC polymers with good foaming ability, good processing properties and low cost, which are suitable for the production of foamed moldings and semi-finished products with high heat resistance.

Presentation of the invention of the invention

It is the object of the invention to produce foamable thermoplastic molding compositions based on VO polymers which have flow properties required for good foamability and which do not contain any heat-fade resistance-reducing modifiers and / or processing aids.

The object is achieved by a polymer mixture consisting of

a) 50 to 95 parts by weight, preferably 70 to 90 parts by weight, of suspension PVC with a K-7fert of 60 to

• 70,

b) 5 to 4 parts by weight, preferably 10 to 30 parts by weight, of one. Emulsion PVC with a K value of 60 to 75 », which has been prepared by the emulsion process using predominantly anionic emulsifiers to which small amounts of nonionic emulsifiers have been added before and / or after the polymerization, and

c) 1 to 20 parts by weight, preferably 5 to

10 parts by weight, of a microsuspension PVO having a K value of 60 to 70 _s wherein the emulsion PVO and the suspension PVO have the same high bulk densities.

The proportion of the individual constituents in the polymer mixture according to the invention can be varied within the ranges indicated, depending on the processing conditions and the intended use in use.

When using only one constituent or two constituents of the specified polymer mixture, foamed thermoplastic molded parts and semi-finished products which achieve the object of the invention can not be produced, but it is in any case necessary

- 5 - 2016

in that a polymer mixture composed of the three constituents is used.

The suspension PVC used is a PVC prepared by conventional methods whose K-value is in the range of 60 to 70 and whose particle size is substantially 60 to 150 atm. As emulsion PVG are those types in question, which are in a K-Werfe range of 60 to 75 and after an emulsion process using predominantly anionic emulsifiers to which small amounts of nonionic emulsifiers were added before and / or after the polymerization has been. The total emulsifier content is 1 to 4 % _f, preferably 2 to 4 %.

Preferred nonionic emulsifiers are carboxylic acid polyglycol esters, alkylaryl polyglycol ethers and alkyl polyglycol ethers, which can be used singly or in combination.

The microsuspended PVC used is a product which is preferably prepared by mechanical solid-liquid separation with subsequent drying. The best results are generally achieved, the Bmulsions Ρνσ and the Bungsungssungs - PVG equal

have high bulk densities, which are preferably between 0.50 and 0.60 g / cur.

The molding compositions according to the invention are obtained by homogeneously mixing the constituents forming the polymer mixture with propellants in preferably blended mixing units which operate predominantly on the fluid principle, the order of addition of the individual constituents being irrelevant.

The molding compositions according to the invention can continue Plasthilf substances such. As activators, peal regulators, heat and light stabilizers, lubricants, fillers, antioxidants, pigments.

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The molding compositions according to the invention can be processed in the extrusion process at high take-off speeds to form molded parts and semi-finished products, in particular solid and hollow profiles, as well as plates in any shape and dimension. They are characterized by a good heat resistance at elevated temperatures, a low bulk density and a smooth, shiny surface. Of substantial advantage is also the low cost price of the molding compositions of the invention.

A exemplary embodiment

The invention will be explained in more detail below with reference to some examples.

example 1

In a heating / cooling mixer combination, six foamable molding compounds having different compositions are produced at mixing temperatures of up to 120 ⁰ G. The molding material 1 contains as polymer 100 parts by weight of suspension PVG having a K value of 61; the molding compound 2 consists of a polymer mixture of 92 parts by weight of suspension PVC having a K value of 65 and 8 parts by weight of an ethylene-vinylacetate copolymer »the molding compound 3 consists of a polymer mixture of 70 parts by weight suspension PVG having a K value of 61 and 30 parts by weight of emulsion PVG having a K value of 66; The _{molding compound} 4 consists of a polymer mixture of 90 parts by weight of suspension PVG having a K value of 65 and 10 parts by weight of a microsuspension PVO having a K value of 64. The compositions of the polymer mixtures of the molding materials 5 and 6 are made according to the invention. The molding compound 5 is composed of 70 parts by weight of suspension PVG having a K value of 61, 25 parts by weight

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Eiaulsions PVQ with an IC value 66 and a total emulsifier content of 3 % and 5 parts by weight of Ivlikrosuspensioas-PVO with a K value of 68 together, the bulk densities of the suspension and emulsion PVO are 0.560 g / cm. The molding compound 6 consists of 75 parts by weight of suspension PVC with a K value of 64, 15 parts by weight of emulsion PVO having a K value of 60 and a total emulsifier content of 2.8 % and 10 parts by weight of microsuspension. PVG with a K value 66, The bulk densities of suspension and emulsion PVO are 0.550 g / cm,

All of the six molding materials furthermore contain 0.5 part by weight of propellant azodicarbonamide, 2 parts by weight of heat stabilizer, 0.4 part by weight of activator and 0.8 part by weight of lubricant. From the molding compositions verschäumbären v / grounded on a single screw extruder with a screw diameter of 63 mm and a screw length of 23 D at processing temperatures 150-174 ⁰ C foamed extruded hollow profiles having dimensions of 32 χ 5 mm. At a screw _speed of 25 rpm, the maximum take-off _{speed of} the six _{parameters is} determined. From Table 1 it can be seen that with the molding compositions 5 and 6 according to the invention the highest take-off speeds are achieved.

Example 2

On. the extruded foamed hollow bars, the raw density is determined and assessed the surface condition. From Table 2 it can be seen that the extruded from the molding compositions of the invention 5 and 6 hollow rods give smooth, shiny surfaces. In the case of the molding compositions 1 to 4, however, different, undesirable surface defects occur and the density is higher in comparison to the molding compositions according to the invention and 6.

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Example 3

The determination of the heat resistance is carried out by a hot water change test according to the test method according to ISO / TG 138 / WG 1 on foamed bores with the dimension 50 χ 1.8 mm, which were extruded and foamed according to the experimental conditions given in Example 1, ie to ^ test tubes are subjected to a hot water temperature of 85 ⁰ C. The maximum clamp distance is determined in such a way that the allowable deflection of 0.1 d is not exceeded, ie Table 3 shows that the tubes produced from the molding compositions according to the invention have the best heat resistance.

Table 1

Maximum take-off speed (cm / min;

Molding compound 1 122

Molding compound 2 148

Molding compound 3 14-6

Molding compound 4 143

Molding compound 5 160

Molding compound 6 162

Table 2

Bulk density (g / cm3) surface finish

Molding compound 1 as a hollow rod 0.93

Molding material 2 as a hollow rod 0.77

Molding material 3 as a hollow rod 0.83

Molding compound 4 as, hollow rod 0.82

Molding compound 5 as Hohlst & b

Molding compound 6 as a hollow rod 0.68 rough surface, bubbles scattered adhesive stripes scattered bubbles strong satin surface smooth, glossy surface smooth, shiny surface

Table 3

Maximum clamp distance (cm)

pipe out molding compound 1 56 pipe out molding compound 2 50 pipe out molding compound 3 55 pipe out molding compound 4 58 pipe out molding compound 5 61 pipe out molding compound 6 61

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Claims (4)

- 10 - 2016 Inventions claim 1 · Verschäumb are thermoplastic molding compounds, in particular for the production of foamed moldings and semi-finished products in the extrusion process, consisting of VC polymers, a blowing agent, stabilizer, activator, pore regulators and other plasticizers, characterized in that a polymer mixture consisting of a) 50 to 95 parts by weight, preferably 70 to 90 parts by weight, suspension PVG having a K value of 60 to 70, b) 5 "to 40 parts by weight, preferably 10 to 30 parts by weight of an emulsion PVO having a K value of 60 to 75> which has been prepared after the emulsion process using predominantly anionic emulsifiers to which small amounts of nonionic emulsifiers have been added before and / or after the polymerization
c) 1 to 20 parts by weight, preferably 5 to 10 parts by weight, of a microsuspension PVO having a K value of 60 to 70 11 - 2016 is used, wherein the emulsion PVO and the suspension ~ PVG have the same high bulk densities. 2. Foamable thermoplastic molding compositions according to item 1, characterized in that the non-ionic emulsifiers contained in the emulsion PVC are carboxylic acid polyglycidyl esters, alkylaryl polyglycol ethers and alkyl polyglycol ethers, individually or in combination
used. 3 * Foamable © thermoplastic compounds according to
Points 1 and 2, characterized in that the
Total emulsifier content 1 to 4%, preferably 2 to
4 '%, is. 4. Foamable thermoplastic molding compositions according to item 1, characterized in that the preparation of the polymer mixture by homogenization in schneilaufenden mixing units, which preferably operate on the fluid principle takes place.