Issue 04/2016

Toys
Bio-alternatives for soft PVC
Bio-alternatives for plasticized vinyl chloride polymers
Table 1: Composition of PVC Bio-alternatives developed by SKZ
Component
Content (wt.%)
Biopolymers (matrix) 57,0
Other polymers (elastic component) 5,0
Bio based plasticizer (softening agent) 19,5
Fillers (inorganic ingredients) 16,0
Additives (coupling agents, lubricants, etc.) 2,5
Figure 1: Build-up of the compounding line used:
1 - Compounder; 2 - Solid dosage; 3 - Liquid dosage;
4 - Atmospheric degassing; 5 - Water bath; 6 - Conveyer belt;
7 - Pelletizer
Figure 2: Hardness and Young’s modulus of biobased materials
developed by SKZ compared to standard PVC-p, used for
the toys production.
Hardness (Shore D)
45
40
35
30
25
20
15
Bio
alternative 1
Bio
alternative 2
PVC-p
400
350
300
250
200
150
100
Young‘s modulus (MPa)
Introduction
Vinyl chloride polymer (PVC) has grown to be one of the
major plastics of the world and is the third most important
polymer with regard to its production volume. For soft
PVC (PVC-p) plasticizers from renewable resources have
been developed and are increasingly used. Nevertheless,
the petrochemical based PVC matrix mostly remains the
same.
In cooperation of SKZ (Würzburg), Tecnaro (Islfeld),
Schleich (Schwäbisch Gmünd) and Konrad Hornschuch
(Weißbach, all Germany), sustainable alternative materials
for PVC-p on the basis of renewable raw materials
have been developed. To achieve this goal various bio
based polymers were modified in a way that flexible
materials with comparable characteristics to PVC-p were
obtained. The materials are to be used predominantly for
manufacturing of toys and table coverings.
Formulations and Process
In the course of the project, different bio based
compounds were developed, which can be used as
alternative materials for PVC-p. These materials consist
of commercially available (PHB-based) biopolymers,
biobased plasticizers, inorganic fillers as well as different
additives (see Table 1).
The compounds were prepared by melt mixing on a
corotating twin-screw extruder Leistritz ZSE27Maxx (L =
1,188 mm and D = 27 mm). To be able to incorporate a large
amount of plasticizer in the polymer matrix, a suitable
screw configuration was designed. All components were
dosed gravimetrically. The extruded strands were passed
through a water bath and transported to pelletizer using a
conveyer belt (see figure 1).
After compounding, the pellets were air dried at 80 °C
for 4 h in a Motan-Colortronic drying chamber, type Luxor
50 and injection moulded into plates 150 x 100 x 2 mm 3
using a Battenfeld TM 1300 machine.
Material Properties
The test samples were cut from injection moulded
plates. Weight loss after storage for 7 days at 70 °C as
well as Shore D hardness and tensile properties according
to DIN EN ISO 527 (Young’s modulus, tensile strength and
elongation at break) were determined. The comparison
of the bio based materials developed by SKZ with the
standard PVC-p used for toys production is presented in
figure 2 and 3.
The biobased materials for toys manufacturing
developed by SKZ show a lower hardness, a slightly
higher Young’s modulus as well as considerably higher
elongation at break compared to conventional PVC-p.
24 bioplastics MAGAZINE [04/16] Vol. 11