KR-102961320-B1 - Polybutylene terephthalate with low THF content

Abstract

The present invention relates to manufacturing polyethylene terephthalate-based automotive interior parts having a low TVOC (total volatile organic compound) content and a low tetrahydrofuran content of injection-molded parts using polyethylene terephthalate.

Inventors

• 비엔뮐러, 마티아스
• 함스, 세바스티안

Assignees

• 엔발리오 도이칠란트 게엠베하

Dates

Publication Date

20260508

Application Date

20200727

Priority Date

20190729

Claims (12)

1. As a polybutylene terephthalate-based compound for injection molding into automotive interior parts having less than 50 μg C/g TVOC (total volatile organic compounds) as determined according to VDA 277 and less than 8 μg/g VOC THF (tetrahydrofuran emissions) as determined according to VDA 278, The above compound comprises 5 to 30 parts by mass of polyethylene terephthalate per 100 parts by mass of polybutylene terephthalate, provided that the polyethylene terephthalate and polybutylene terephthalate exist as a mixture rather than a copolymer, The above polyethylene terephthalate is a polybutylene terephthalate-based compound used to reduce the release of THF from the compound.
2. In claim 1, Polybutylene terephthalate-based compound, characterized in that the polyethylene terephthalate has an intrinsic viscosity in the range of 30 to 150 cm³ /g when measured in a 1:1 weight part phenol/o-dichlorobenzene at 25°C using a Uvelohde viscometer similar to ISO 1628-1.
3. In claim 1, Polybutylene terephthalate-based compound, characterized in that the polyethylene terephthalate has an intrinsic viscosity in the range of 40 to 130 cm³ /g when measured in a 1:1 weight part phenol/o-dichlorobenzene at 25°C using a Uvelohde viscometer similar to ISO 1628-1.
4. In claim 1, Polybutylene terephthalate-based compound, characterized in that the polyethylene terephthalate has an intrinsic viscosity in the range of 50 to 100 cm³ /g when measured in a 1:1 weight part phenol/o-dichlorobenzene at 25°C using a Uvelohde viscometer similar to ISO 1628-1.
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Description

Polybutylene terephthalate with low THF content The present invention relates to injection molding of polybutylene terephthalate-based automotive interior parts having a low TVOC content (TVOC means "total volatile organic compounds") and a low tetrahydrofuran content using polyethylene terephthalate. In the past, despite some complexity, there has been no shortage of attempts to find means to estimate the various volatile organic compounds, or VOCs for short, found in interior materials. For this purpose, a concept in the form of an indicator parameter is used to determine the TVOC value (Total Volatile Organic Compounds) by utilizing the sum of the concentrations of individual compounds as an indicator of the VOC concentration in the interior materials (see reference (B. Seifert, Bundesgesundheitsblatt - Gesundheitsforschung - Gesundheitsschutz, 42, pages 270-278, Springer-Verlag 1999)). Unlike when determining individual substances in indoor air where the "target of measurement" is clearly defined—for example, when determining n-decane, toluene, or formaldehyde in particular—when analyzing VOC mixtures, it is necessary to consider which substances should be described as VOCs. In this regard, to achieve a consistent approach, a World Health Organization (WHO) working group dealing with organic substances in indoor air initially performed a classification of organic compounds. This WHO classification, based on boiling point, is shown in Table 1; it should be noted that according to this definition, formaldehyde and diethylhexyl phthalate do not belong to VOCs. Table 1: Classification of organic compounds in indoor air according to WHO * English names are used in these columns of Table 1 to better indicate the origin of abbreviations also used in German documents. The corresponding German terms are as follows: VVOC=Sehr/leicht fluechtige organische Verbindungen [Highly Volatile Organic Compounds], VOC=Fluechtige organische Verbindungen (haeufig als FOV abgekuerzt) [Volatile Organic Compounds (often abbreviated as FOV)], SVOC=Schwerfluechtige organische Verbindungen [Semi-Volatile Organic Compounds], POM=Partikelgebundene organische Verbindungen [Particulate Organic Matter]; ** Polar compounds are at the upper limit of the range; According to the literature (G. Blinne, Kunststoffe 10/1999), polybutylene terephthalate (PBT) in compound form, preferably reinforced with glass fibers, is an essential plastic in the electrical engineering/electronics field and the automotive industry, particularly the automotive industry. Accordingly, the literature (AutomobilKONSTRUKTION 2/2011, pages 18-19) describes the use of PBT blends for precision speaker grilles and ventilation grilles, which are automotive interior parts. WO 2013/020627 A1 specifically describes functionalized interior trim parts for automobiles that can be manufactured using PBT as the matrix plastic. PBT is a semicrystalline plastic with a narrow melting range of 220°C to 225°C. Due to its high crystal ratio, stress-free molded parts made of PBT can be heated briefly below the melting temperature without deformation or damage. Pure PBT melt exhibits short-term thermal stability up to 280°C, does not undergo significant molecular decomposition, and does not produce significant emissions of gases and vapors. However, like all thermoplastic polymers, PBT decomposes under excessive thermal stress, particularly upon overheating or during cleaning by combustion methods. This results in the formation of gaseous decomposition products. Decomposition accelerates above approximately 300°C, and initially, mainly tetrahydrofuran (THF) and water are formed. According to EP 2 029 271 A1, THF is already formed through intramolecular condensation from the monomer 1,4-butanediol (BDO) during the manufacture of PBT. This reaction can be facilitated by both the terephthalic acid (PTA) used and the titanium-based catalyst typically used to manufacture PBT. Alternatively, it is possible to use dimethyl terephthalate (DMT) instead of PTA. However, THF is also continuously regenerated from the PBT melt at high temperatures. This process, also referred to as "back-biting," occurs at the BDO terminal group. Similar to the formation of THF from the BDO monomer, this reaction is an intramolecular condensation that yields the unwanted byproduct tetrahydrofuran. The regeneration of THF from the polymer in the molten state is also facilitated by both the acid terminal group (PTA) and any present (titanium-based) catalyst. The effects of tetrahydrofurans on human health and the environment were tested in Germany in 2013 as part of a substance probation under REACH. In 2017, the International Agency for Research on Cancer (IARC) classified tetrahydrofurans as a probable carcinogen. Apart from technical measures to avoid THF during the manufacturing of PBT, as health awareness and consumer demand for odor control in automobiles increase, efforts are being made to reduce or completely