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Flame-Retardants for PBT ��

General Application Data about Flame-Retardants for Polybutylene terephthalate (PBT)

� Fire-Safety Polybutylene Terephthalate (PBT) is a crystalline, high molecular weight engineering plastic that has an excellent balance of properties and processing characteristics. While often used with glass fiber reinforcement, it has very good dimensional stability, high heat resistance, chemical resistance and good electrical properties.

PBT plays a very important part in the production of electro-mechanical/electronic parts, automotive parts and precision parts. It is used mainly for the production of connectors, micro switches, jacks, core of transformers, relay blocks, fans, trimmers and components for business equipment.

As its inherent flammability involves a real hazard to users, it has been necessary to significantly improve its fire retardancy. This has been achieved mostly by the use of brominated fire retardants, employing antimony trioxide as a synergist.

� ICL IP FRs product line This data sheet provides information on the preparation of FR PBT.

The type of PBT may have a considerable influence on properties such as melt flow, impact, electric properties and heat distortion temperatures.

ICL IP offers a broad line of Flame-Retardants (FRs) and tailor-made solutions that provide additional benefits in new market segments and applications.

The following FRs are particularly suitable for FR PBT passing class V-0 according to the UL 94 standard:





� FR-1410 (decabromodiphenyl ethane - 82% bromine) is cost efficient in PBT but has limited UV stability and is not melt blendable during injection molding

� FR-1025 (Brominated Polyacrylate) - 71% bromine), is a proprietary polymeric flame retardant offered by ICL IP particularly suitable for use with PBT, with or without fiber reinforcement. It exhibits inherent advantages over other halogenated FR additives currently used for the same applications:

effective flame retardancy non-blooming good temperature stability and outstanding long term heat–aging stability easy processability and high melt flow properties for production of thin wall and/or large dimensions parts with short injection molding cycles and high precision.

excellent compatibility with fiber reinforcement and polymer matrix excellent impact properties not solvent extractable chemical resistance good electrical properties enhancement of reuse of scrap plastic generated by injection molding operations.

� F-2000 series (high molecular weight brominated epoxy polymers– 50 to 53% bromine), are melt blendable and efficient polymeric FR additives specially designed for application in PBT. They have good flame retardancy and are suitable for compounds with high UV stability. They are non-blooming.

� F-3100 (modified brominated epoxy polymers – 53% bromine) has excellent cost performance with well balanced properties in PBT. It has a softening range between 1800C and 2200C and is recommended for applications in glass reinforced PBT where it is expected to reduce significantly energy consumption during compounding and pressure during injection molding. Other advantages F-3100 has are low metal adhesion and good melt flow during recycling steps.





� FR-803P (brominated polystyrene- 66% bromine), thanks to its polymeric

nature, contributes to high comparative tracking index (CTI) and excellent thermal stability. Its advantages in PBT are:

cost efficiency non-blooming high temperature processing stability up to 3100C excellent electrical properties

� ICL IP is also offering the 5500 Antidrip series for application in PBT. The enhanced efficiency of 5500 series allows reducing significantly the quantity of FRs (Brominated FR + antimony trioxide) and eliminates the critical addition of antidripping agent. For more details, please contact ICL IP Tecnet Representative.

All these FRs have undergone extensive toxicological and environmental testing and have been proven to pose no risk to health and the environment.

Detailed application data sheets of these FRs in PBT are available from http://www.iclfr.com website.

� Thermal stability Thermogravimetric analysis of the above mentioned flame-retardants (Table 1) reflects their good thermal stability, enabling high to fairly high processing temperatures.

Table 1: Thermogravimetric analysis (TGA-100C/min in air)

Temperature, 0C

FR Type FR-1410 FR-1025 F-2000 series F-3100 FR-803P

5 345 330 348-364 340 370

10 360 335 357-367 354 390





� Processing conditions Typical processing conditions for compounding and mold PBT flame retarded with these FRs are as follows:

Compounding

Compounding in a co-rotating twin-screw extruder (L/D= 32:1)

Temperature profile, 0C:

Non reinforced 200-220-240-250-250-260-260-260-270

30% glass reinforced 200-220-240-250-260-265-265-265-275

Screw speed, rpm 320

Throughput, kg/h 17

Injection molding

Temperature profile, 0C:

Non reinforced 240-250-270-280-280

30% glass reinforced 240-260-280-285-290

Mold temperature, 0C 95

Pressures, Bar Injection: 1800 - Holding: 1900 - Back: 50

Cycle time, sec 25

� FR efficiency Table 2 gives indicative guidance to define formulations able to pass class V-0 according to UL94.





Table 2: Guidance for FR PBT class UL 94 V-0

Type Thickness mm

Non reinforced 30% glass reinforced

Bromine content, %

Antimony trioxide

content, %

Bromine content, %

Antimony trioxide

content, % No antidripping agent 0.8 8-9 5.5-6.5 7-9 5-7

1.6 7-8 5-6 5-7 3.5-5.2

With antidripping agent (PTFE)*

0.8 7-8 4.8-5.9 6-7 4.5-5.2 1.6 6-7 3-4 4-5 3-4

* 0.05 to 0.3%

Usually, FR PBT class V-2, is also expected to pass the "Glow wire Test" at 9600C according to the standard IEC 695-2.

� Overview of properties Tables 3 provides guidelines for selecting an optimal FR for PBT applications passing class V-0.

Table 3: Properties of V-0 PBT

Properties

FR-1025 F-3100 F-2000 series FR-803P FR-1410 5531

Thermal stability �� Melt flow �� to ��

FR efficiency �� Impact ��

Comparative tracking Index �� Thermal aging ��

Recycling �� UV/light stability ��

Heat distortion temperature (HDT)

��

Non-blooming �� Cost efficiency � ��

� good �� very good �� excellent





� Processing-aid The processing-aid effect of FR-1025 and F-3100 is of particular interest in glass reinforced PBT as it is beneficial at each processing steps:

1. Energy savings during compounding as one can see from the comparative values of specific energy consumptions (SEC) shown in Figure 1.

0.5

0.6

0.7

0.8

0.9

1.0

SE

C, K

wH

/kg

Fig. 1: Specific Energy Consumption (SEC)in 30% glass reinforced PBT

F-3100 FR-1025 Br polycarbonate F-2400

2. Lower pressure during injection molding as one can see in Figure 2.

100

120

140

160

180

200

Pre

ssur

e, b

ar

Fig. 2: Pressure during injection molding (30% glass reinforced PBT)

F-3100 FR-1025 F-2400 Br polycarbonate





3. When processed in their softening range, FR-1025 and F-3100 contribute to significant improvement in melt flow properties during injection molding (Fig. 3). Enhanced flow is an especially important feature for electronic devices made of glass-reinforced PBT and often designed with thin wall dimensions and complicated shapes.

0

10

20

30

40

50

60

MFI

, g p

er 1

0 m

in

FR-1025 & F-3100

Ref No FR F-2400 & FR-803P

M Br PC** Br PC**

Fig. 3: Melt flow index*in 30% GFR PBT

* 2500C – 2.16 kg ** resp. Modified Brominated Polycarbonate and Brominated Polycarbonate

� Impact properties Figure 4 compares impact properties of the various FRs in 30% glass reinforced PBT, class V-0 (0.8mm) according to UL 94.

FR-1025 is the flame retardant of choice when good impact properties are needed. F-3100 like commercial grades of brominated polycarbonate oligomer contributes to fairly good impact properties in PBT when compared with other commonly used FRs. To further improve impact properties of FR grades of PBT, it is recommended to add





2.5 to 10% of a suitable impact modifier, such as ethyl- or butyl-acrylate copolymers but attention must be paid to the consequent increase in viscosity properties (Fig. 5)

0

20

40

60

80

100

120

Izod

J/m

No FR FR-1025 Brpolycarbonate

F-3100 F-2400 FR-803P FR-1210

Fig. 4: Izod notched impact in FR PBT V-0 - 0.8mm (30% glass reinforced)

Fig. 5: Optimization of impact and MFI in GFR PBT flame retarded by F-2400 (30% glass )

0

20

40

60

80

100

120

0 2.5 5 10

% Impact modifier

MFI

%

0

100

200

300

400

500

Izod

not

ched

%

MFI IZOD





� Thermal aging stability Thermal aging properties of flame retarded PBT play an important role in simulating long term behavior of finished parts with high working temperatures. In this respect, F-2000 series and F-3100 exhibit good performance as a result of their excellent thermal stability. After a 1000h thermal aging treatment at 1800C of glass reinforced PBT, tensile properties are maintained well above 50% their initial value (Figure 6).

Fig. 6: Thermal aging GFR PBT (1000h at 180°C - Max. tensile strength)

0

25

50

75

100

0 250 500 750 1000

Hour

%

Retention

Ref. No FR F-2100 F-2400 F-3100

FR-1025 is even superior over all the other halogenated FR additives currently offered as a result of its polymeric nature and excellent long-term thermal behaviour. After a 1000h thermal aging treatment at 1900C of glass reinforced PBT flame retarded by FR-1025, tensile properties are maintained above 50% of their initial value while non flame retarded PBT would fail during this test (Figure 7). FR-1025 has also excellent color stability at high temperatures.





Fig. 7: Thermal aging GFR PBT (1000h at 190°C - Max. tensile strength)

0

25

50

75

100

0 250 500 750 1000

Hour

%

Retention

Ref. No FR FR-1025

� Recycling Several studies completed in Japan, Germany and the US have demonstrated that plastics containing brominated flame retardant are fully recyclable, with the flame retardant able to withstand multiple cycles. The studies analysed both the possible degradation of the flame retardant, and also compliance with the stringent environmental requirements of the German Dioxin Ordinance in matter of dioxin emissions standards during the recycling process1. Recycling studies with scrap from non- and glass-reinforced PBT flame retarded by FR-1025 (UL 94 class V-0 1.6 mm) have shown that a loading of 50% scrap in virgin compound can undergo five recycling steps without losing its flame retardancy and with no significant change in properties.

Moreover the results of the analyses performed by Institut Fresenius Chemische und Biologische Laboratorien GmbH on these samples for presence of polybrominated dibenzo-para-dioxins/dibenzofurans (PBDD/PBDF), have shown them to be in full compliance with the requirements of the global most strict criteria of the German





Dioxin Ordinance1.

Simulation studies of recycling of PBT compound based on F-3100 compared to a commercial high MW Br-epoxy have been made. Examination of MFI stability in a flow indexer as a function of time, demonstrates the beneficial phenomenon of increase in MFI, whereas in high MW Br-epoxy there is a definite tendency of MFI decrease, probably indicating some molecular cleavage.

� The Series

The SaFRon series is aimed at providing the market with tailor made solutions for specific and high demanding applications.

5531 (52% bromine) is a modified grades of high molecular weight brominated epoxy with built-in antidrip properties enabling production of fire retarded PBT with following advantages:

� Non dripping class V-0 achievable with 20-25% less FRs package � Critical addition of antdripping agent is not needed � Improvement of the thermal stability during recycling operations � Low metal adhesion

� Health – Safety - Environmental aspects ICL IP FRs product line has undergone extensive toxicological and environmental testing2, and has been proven to pose no risk to health and the environment.

For instance, results of analyses performed by Institut Fresenius Chemische und Biologische Laboratorien GmbH on ICL IP FRs product line itself and under conditions simulating a modern municipal solid waste incinerator for presence of polybrominated dibenzo-para-dioxins/dibenzofurans (PBDD/PBDF), have shown it to

1 Further information available upon request 2 Further information available upon request





be in full compliance with the requirements of the global most strict criteria of the German Dioxin Ordinance and EPA TSCA 40 §766.27 Final Rule requirements1.

Incineration studies published by the University of Munich in 2002, show that the toxicity of the combustion products from PBT fire retarded by a brominated fire retardant/antimony trioxide system is several times lower than for a PBT fire retarded by a phosphinate salt (halogen free system) and than beech wood used as a reference. The non FR PBT also emits highly toxic smoke during incineration.

As part of an ongoing Product Stewardship Program and Customer oriented policy, ICL IP is committed to implement further toxicological and environmental tests, should this be needed.

� Applications As a result of their efficient combination of properties, ICL IP's broad line of Flame-Retardants (FRs) is offering a series of tailor-made solutions that provide additional benefits in new market segments and applications.

ICL IP's FR product line is recommended for the production of PBT electro-mechanical/electronic parts, automotive and other precision parts. Typical examples of application are shown in Figures 8 to 11: connectors in the computer, telecom and automotive industries, high quality keyboards, mini-fans for computers and lampholders for energy saving lamps.

In these applications, ICL IP's FR product line exhibits inherent advantages such as their processing aid effect for thin injection molding, good thermal stability, good impact and good electrical properties and excellent dimensional stability even for large dimension parts. The polymeric FRs are often preferred if non-blooming properties are needed.





Figure 8: Connector and fan inside a PC Figure 9: various connectors

Figure 10: connector in automotive Figure 11: lampholder for energy

saving lamps





For further advice and assistance, contact our representatives in your area:

Head Office ICL-IP Ltd. Phone: +972 8 6297 608 Fax: +972 8 6297 846 E-mail: [email protected] North America and Mexico Asia Pacific ICL-IP America Inc. China Phone: +1 877 661 4272 ICL China Fax: +1 314 983 7610 E-mail: [email protected] Phone: +86 21 5386 3322 Fax: +86 21 5386 3336 South America E-mail: [email protected] ICL Brasil Ltda Japan Phone: +55 11 2155 4539 ICL-IP Japan Ltd Fax: +55 11 2155 4507 E-mail: [email protected] Phone: +81 3 6801 8430 Fax: +81 3 6801 6970 Europe E-mail: [email protected] Main Office Asia Pacific ICL-IP Europe B. V. ICL Asia Ltd Phone: +31 20 800 5800 Fax: +31 20 800 5805 Phone: +852 28277761 E-mail: [email protected] Fax: +852 2824 1502 E-mail: [email protected] Italy Other Parts of the World PM Chemicals Italy ICL-IP Sales Office Phone: +39 02 204 87225 Fax: +39 02 204 9449 Phone: +972 8 6297 633 E-mail: [email protected] Fax: +972 8 6297 819 E-mail: [email protected]

Tecnet 130729

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