CS274123B1

CS274123B1 - Premixture for polystyrenne plastics colouring

Info

Publication number: CS274123B1
Application number: CS458589A
Authority: CS
Inventors: Jan Ing Ruzicka; Jiri Ing Pavlicek; Stanislav Ing Bittner; Jaroslav Marsa; Jan Kovarik
Original assignee: Ruzicka Jan; Pavlicek Jiri; Stanislav Ing Bittner; Jaroslav Marsa; Jan Kovarik
Priority date: 1989-08-01
Filing date: 1989-08-01
Publication date: 1991-04-11
Also published as: CS458589A1

Abstract

A premixture for polystyrene plastics colouring, allowing use of dyes of low dyeing capacity. The mixture consists of organic dye or pigment, stearic acid or its salts with metals of alkaline earth, isobutyl stearate and polystyrene in the form of pearls.

Description

(57) Masterbatch for coloring polystyrene plastics allowing the use of dyes with lower coloring. The mixture consists of an organic dye or pigment, stearic acid or its alkaline earth metal salts, isobutyl stearate and polystyrene in the form of beads.

CS 27412

CS 274123 Bl

The present invention relates to a masterbatch for coloring polystyrene plastics. The masterbatch is particularly suitable for coloring polystyrene beads produced by suspension polymerization, or polystyrene granules, or mixtures of beads with granules in the manufacture of mixed types.

For these polystyrene forms, organic dyes or inorganic pigments on a polymeric support are used.

It is customary to first prepare a premix on a quick mixer which is metered into a slow running mixer.

For homogeneous staining, it is necessary to achieve perfect dispersion of pigments or dyes. into the material to be dyed, in this case polystyrene plastic.

Incomplete dispersion results in agglomerates or agglomerates of dye in the finished product.

The agglomerates manifest themselves as different color points in the homogeneous coloring of the material, or as a total color inhomogeneity.

In addition to this apparent impression of imperfect dispersion, this may be manifested by:

a) more frequent clogging of sieves in the extruder head, clogging of sieves causes unmixed parts of pigment,

b) surface roughness of extruded strings,

(c) by reducing the physical-mechanical properties of the product, in particular its impact strength;

d) poor abrasion resistance,

(e) fluctuations in such characteristics.

It is known that most pigments absorb plasticizer, thereby reducing the melt index value.

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In some cases, dispersion can be improved by adding dispersants. The main drawback of these substances is, besides the high price, that they can rarely be certified as safe.

These disadvantages are overcome by the dyeing of the polystyrene plastics according to the invention, which consists of 10-15 wt. from 0.5 to 5 parts by weight of organic dye or inorganic pigment on a polymeric support; 0.1 parts by weight of stearic acid or its salts with alkaline earth metals; parts of isobutyl stearate, up to 100 wt. parts are blended with polystyrene bead.

This somewhat surprising effect of isobutyl stearate can be explained both by the presence of the liquid plasticizer in an optimum amount (a small amount of an ineffective, excess could cause lump formation in some types) and by the synergistic effect of softening the ester type plasticizer against the hydrocarbon type plasticizer.

The mixture prepared according to the invention does not spontaneously produce better homogeneity of color shade and more intense coloration.

The composition has improved flowability, is well dispensed and does not form clumps in the dispensing device.

In case of vibration of the device, eg in the container above the extruder, it does not separate itself.

Furthermore, the composition prepared according to the invention makes it possible to use organic dyes or inorganic pigments of lower coloration, since this is balanced by perfect dispersion and hence homogenization, as demonstrated by comparing the color deviation from the Mac Addamse gray scale standard.

The advantages of the mixture are evident from the following examples.

CS 274123 02

Example 1

A pigmented dye (yellow dye) consisting of three components was used for dyeing polystyrene to a yellow hue:

(a) titanium dioxide and barium phosphorus tungstolybdic acid complex

(b) chromium, antimony and titanium oxides

(c) azo dye condensates

The yellow dye was blended with the other ingredients in the proportions as shown in Table I, the premix made into a slow-running mixer at a ratio such that the yellow dye content was always 1% by weight of the resulting mixture. The mixture was processed on an extrusion line. The properties of the granulate obtained are given in Table II.

Raw materials used:

and) PS pearl, d. = 0.36 mm melt index = 5.4 g / 10 min (b) standard PS pearl d. p. = 0.42 mm melt index = 17.3 g / 10 min C) block polystyrene bulk granulate = 0.55 to 0.650 g / l

Isobutyl stearate technical acid number in mg / KOH / g, max. max. 0.7 coloring in Hazen units, max. 150 crystallization temperature in ° C 16-21 iodine value, max. 4

Calcium stearate water content% by weight-max. 3 content of Ca% weight-min. 5.5 melting point ° C min. 120 content of free fatty acids% weight-max. 2,5 netting residue 0,315 mm weight-max. 3

Zinc stearate

Water content% weight-max. 3 melting point ° C min. 105 ZN content,% by weight min. 9 free fatty acids,% by weight-max. 5 residue on sieves 0,63 mm, weight-max. 0.5

Stearic acid iodine number 0,5 max.

acid number mg / KOH / g 198 to 212 saponification number mg / KOH / g 200 to 212 humidity,% w / w max. 0,3 bulk density 0,50 g / cm ³

CS 274123 Bl

Table 1

Component units ordinary procedure tough PS conventional crystal PS procedure The process of the invention 1 2 3 4 5 6 7 8 9 yellow dye hm. parts 12.5 12.5 10 15 Dec 12.5 12.5 10 15 Dec 12.5 calcium stearate 0.83 - 5 - 0.83 - - - - zinc stearate - 0.83 - - - - 0.5 5 0.83 stearic acid - - - 0.5 - 5 - - - isobutyl stearate _ll_ - - 0.1 2 0.3 0.5 2 0.1 0.3 polystyrene beads lt 86.67 86.67 84.9 82.5 86.37 82 87.5 89.9 86.37 Total 100 ALIGN! 100 ALIGN! 100 ALIGN! 100 ALIGN! 100 ALIGN! 100 ALIGN! 100 ALIGN! 100 ALIGN! 100 ALIGN!

Table 2

Monitored parameter 1 2 3 4 5 6 7 8 9 mixability good good good good very good average good good very good dosing good good average good regular irregular good average regular surface extruded

Claims

SUBJECT OF THE INVENTION

Masterbatch for dyeing polystyrene plastics, characterized in that it is comprised of from 10 to 10

15 wt. from 0.5 to 5 wt.% of an organic dye or inorganic pigment on a polymeric support; 0.1 parts by weight of stearic acid or its alkaline earth metal salts,

2 wt. % isobutyl stearate, up to 100 wt. The parts comprise polystyrene in the form of beads.