Patent Application
20240150571
The present invention relates to a thermoplastic composition comprising polycarbonate and polyester. The present invention further relates to an article comprising or consisting of such a composition.
Compositions comprising polycarbonate and polyester have excellent appearance, mechanical properties, dimensional stability, and chemical resistance, and are widely used in various fields. Particularly, a composition composed of polycarbonate (PC) and poly(butylene terephthalate) (PBT) has characteristics of imparting excellent impact resistance (including low temperature impact resistance or ductility), mechanical property, and dimensional stability to the polycarbonate. These compositions are useful in fields such as interior and exterior parts in automobiles specifically.
JP2008115295A discloses a highly-processable polymer material composed of a polycarbonate/polyester resin with a compatilizer which is an olefin copolymer having a functional group which reacts with a carboxyl group which has outstanding impact resistance and can improve quality stability.
CN105385117A discloses high-/low-temperature-impact-resistance PC-PBT composite material for LED (Light Emitting Diode) aluminum-plastic structural parts.
CN108034204B discloses low-temperature impact resistant polyester compositions, wherein the composition is prepared from PBT resin with MBS toughening agent, compatilizer, ester exchange inhibitor, antioxidant and lubricant, and the preparation method of the low-temperature impact resistant polyester composition is also disclosed.
CN105255149A discloses low-temperature toughened and reinforced PC/PBT alloy materials and a preparation method thereof, wherein low-temperature impact property of the alloy is improved by adding a low-temperature toughening agent.
Polycarbonate/polybutylene terephthalate (PC/PBT) compositions are widely used in many applications such as automotive and other OVAD (Outdoor Vehicle and Devices) exteriors by its excellent property and processability, ductility (low temperature), resistance to chemical attack and weathering.
Compositions comprising polycarbonate and poly(ethylene terephthalate) (PC/PET) have been reported to have better thermal properties and more surface gloss compared to PC/PBT compositions. Additionally PET is a widely available, well-known material, used for a variety of applications including in particular bottles, such as for carbonated and non-carbonated soft drinks, fibers, and packaging, household and consumer products. PC/PET compositions are found to show less favorable low temperature ductility, i.e. ductility at temperatures in the range of about −20 to about −30° C. For achieving improved low temperature impact resistance properties, silicone-modified polycarbonate copolymer may be used, which, however is not cost effective.
It is, therefore, an object of the invention to provide for a composition comprising PC and PET that has improved low temperature impact resistance properties without significantly affecting or even improving the mechanical and other properties such as thermal properties.
To that extent the present inventors have surprisingly found that a composition comprising polycarbonate and polyester, wherein said polyester comprises poly(ethylene terephthalate), an impact modifier in combination with a specific ionomer demonstrates an improved low temperature impact resistance (without affecting mechanical and other thermal properties) compared to an otherwise identical composition wherein the poly(ethylene terephthalate) component does not contain the ionomer. Without willing to be bound to it, the present inventors believe that the presence of the specific monovalent ionomer acts as an impact synergist and helps by acting as intrinsically self-healable materials, which generates instantaneous impulsive fracture/crack or propagation resistance without any external trigger. This makes it suitable for impact resistant application where better ductility is desired.
Accordingly the present invention relates to a thermoplastic composition comprising, based on the weight of the composition, at least 30 wt. % aromatic polycarbonate, at most 70 wt. % of polyester comprising poly(ethylene terephthalate), from 0.1-20 wt. % of an impact modifier, from 0.05 to 1.0 wt. % of a monovalent ionomer comprising repeat units derived from ethylene, a dicarboxylic acid or derivative thereof, a monocarboxylic acid, and optionally a comonomer.
For the avoidance of doubt it is noted that the composition according to the invention as presented herein is a thermoplastic composition.
By application of the invention the foregoing object is met, at least in part.
Polycarbonate is a well-known material and generally exhibits good mechanical and optical properties. Typical applications include optical media carriers, glazing, extruded sheets, lenses and water bottles. Polycarbonates are generally manufactured using two different technologies. In a first technology, known as the interfacial technology or interfacial process, phosgene is reacted with bisphenol A (BPA) in a liquid phase.
Another well-known technology for the manufacture of polycarbonate is the so-called melt technology, sometimes also referred to as melt transesterification or melt polycondensation technology. In the melt technology, or melt process, a bisphenol, typically BPA, is reacted with a carbonate, typically diphenyl carbonate (DPC), in the melt phase. A polycarbonate obtained by the melt transesterification process is known to be structurally different from polycarbonate obtained by the interfacial process. In that respect it is noted that in particular the so called “melt polycarbonate” typically has a minimum amount of Fries branching, which is generally absent in “interfacial polycarbonate”. Apart from that melt polycarbonate typically has a higher number of phenolic hydroxy end groups while polycarbonate obtained by the interfacial process is typically end-capped and has at most 150 ppm, preferably at most 50 ppm, more preferably at most 10 ppm of phenol hydroxyl end-groups.
In accordance with the invention, it is preferred that the polycarbonate comprises or consists of aromatic bisphenol A polycarbonate homopolymer (also referred to herein as bisphenol A polycarbonate) and not copolymers of polycarbonates. Preferably, the polycarbonate of the invention disclosed herein comprises at least 30 wt. %, preferably at least 60 wt. % of bisphenol A polycarbonate based on the total amount of polycarbonate. More preferably, the polycarbonate in the composition essentially consists or consists of bisphenol A polycarbonate.
It is preferred that the polycarbonate has a weight average molecular weight of 15,000 to 60,000 g/mol determined using gel permeation chromatography with polycarbonate standards.
In an aspect, the polycarbonate is an interfacial polycarbonate. In another aspect, the polycarbonate is a melt polycarbonate. In yet another aspect the polycarbonate is a mixture of from 20-80 wt. % of interfacial polycarbonate and from 80-20 wt. % of melt polycarbonate, based on the weight of the polycarbonate.
The polycarbonate may be a mixture of two or more polycarbonates differing in melt volume rate (i.e. in molecular weight). The polycarbonates of the mixture may both be a bisphenol A polycarbonate homopolymer.
The polyester of the composition disclosed herein comprises, essentially consists of or consists of PET. The PET may be a mixture of two or more different poly(ethylene terephthalate)s, for example a mixture of PETs with mutually different intrinsic viscosities. The polyester may further comprise recycled poly(ethylene terephthalate).
Polyesters like poly(ethylene terephthalate) are known to a skilled person per se. In accordance with the invention the polyester can be prepared by direct polyesterification of terephthalic acid with 1,2-ethane diol (ethylene glycol), usually with the help of a strong acid catalyst in the presence or absence of co monomers like isophthalic acid (IPA).
It is preferred that the composition comprises at most 40 wt. % of polyester comprising poly(ethylene terephthalate) based on the weight of the composition and wherein the combined weight percent value of all components is 100 wt.%. It is preferred that the PET has an intrinsic viscosity of 0.4 to about 2.0 dl/g as measured in a 3:2 weight to weight mixture of pheno1:1,2-dichlorobenzene at 25° C.
In an aspect the polyester may further comprise another polyester, miscible with poly(ethylene terephthalate), which is preferably poly(butylene terephthalate) (PBT). In accordance with this aspect of the invention, the composition preferably comprises from 99 to 80 wt. % of poly(ethylene terephthalate) and 1 to 20 wt. % of poly(butylene terephthalate) based on the weight of the polyester.
The thermoplastic composition of the invention comprises an impact modifier. Suitable impact modifiers are typically high molecular weight elastomeric materials derived from olefins, monovinyl aromatic monomers, acrylic and methacrylic acids and their ester derivatives, as well as conjugated dienes. The polymers formed from conjugated dienes can be fully or partially hydrogenated. The elastomeric materials can be in the form of homopolymers or copolymers, including random, block, radial block, graft, and core-shell copolymers. Combinations of impact modifiers can be used.
The impact modifier is preferably selected from the group consisting of ethylene-vinyl acetate copolymer, ethylene-methyl-acrylate copolymer, ethylene-ethyl acrylate copolymer, ethylene-butyl acrylate copolymer, low density polyethylene, maleic anhydride grafted ethylene-octene copolymer, ethylene-ethyl acrylate-glycidyl ester copolymer, ethylene-butyl acrylate-glycidyl ester copolymer, rubber modified styrene-acrylonitrile copolymer, rubber modified styrene-acrylonitrile-methyl methacrylate copolymer, styrene-acrylonitrile copolymer and combinations of at least two of the foregoing (co)polymers.
The amount of impact modifier may be from 0.1-20 wt. % based on the weight of the composition. Preferably the impact modifier is comprised in the composition in an amount of from 2-15 wt. %, preferably from 8-12 wt. %.
The composition of the invention comprises an impact synergist, which is a monovalent ionomer comprising repeat units derived from ethylene, a dicarboxylic acid or derivative thereof, a monocarboxylic acid, and optionally a comonomer.
Ionomers are synthetic polyelectrolytes that consist of both electrically neutral and ionized groups that are randomly and/or regularly distributed along the polymer backbone. One important characteristic of ionomers is the strong molecular aggregation of the ion-carrying groups to ion rich domains or ion clusters, which act as physical crosslinks. When heated, the ionic bonds and clusters dissolve and when cooled, they reform. This gives ionomers a unique structure and behavior. At low temperatures, they behave like crosslinked polymers (elastomers) and at elevated temperatures like ordinary thermoplastics. The majority of ionomers studied have a polyvinyl or polydiene backbone and carry anionic groups (anionomers) with Na+, and Zn2+ as counter ions.
These ionic copolymers have typically a low melting point, improved toughness/flexibility and mechanical strength and when used as films, possess a much higher clarity and gloss and provide superior hot tack, seal strength and puncture resistance than unmodified polyethylene film.
A well known ionomer is ethylene acrylic acid copolymer (EAA) which is sold under the tradename Surlyn by DuPont. It is frequently used as a food packaging material and as a tie-layer (compatibilizer) in multi-layer films. Other important applications include coatings and surface films for golf balls, sports equipment, and for over molded (cosmetic) bottles.
In accordance with the invention, the composition comprises from 0.05 to 1.0 wt. %, preferably from 0.1 to 0.5 wt. % of a monovalent ionomer comprising repeat units derived from ethylene, a dicarboxylic acid or derivative thereof, a monocarboxylic acid, and optionally a comonomer; based on the weight of the composition. The monocarboxylic acid is selected preferably from (meth)acrylic acid. The dicarboxylic acid is preferably selected from maleic acid, fumaric acid, itaconic acid, maleic anhydride, fumaric anhydride, itaconic anhydride, one or more C1-4 alkyl half ester of maleic acid, one or more Ci-4 alkyl half ester of fumaric acid, one or more C1-4 alkyl half ester of itaconic acid, or combinations of two or more thereof. The comonomers is preferably selected from CO, acid anhydride, maleic acid, monoester of the acid anhydride, an epoxy-containing (meth)acrylate, or combinations of two or more thereof.
The carboxylic acid functionalities in the aforesaid ionomer are at least partially neutralized (from about 10 to about 70%, about 35 to about 70%) by a monovalent ion, preferably selected from alkali metal ions, more preferably from sodium or potassium. Methods for preparing ionomers from copolymers are well known in the art.
Typical additives that are used in the composition can comprise one or more of a flow modifier, filler, reinforcing agent (e.g., glass fibers or glass flakes), antioxidant, heat stabilizer, light stabilizer, UV light stabilizer and/or UV absorbing additive, plasticizer, lubricant, release agent, in particular glycerol monostearate, pentaerythritol tetra stearate, glycerol tristearate, stearyl stearate, antistatic agent, antifog agent, antimicrobial agent, colorant (e.g., a dye or pigment), flame retardant either or not combined with an anti-drip agent such as polytetrafluoroethylene (PTFE) or PTFE-5 encapsulated styrene-acrylonitrile copolymer.
The composition disclosed herein may comprise one or more nucleating agents. In that respect, the term nucleating agent refers to an additive that enhances the formation of crystals in the polyester phase of the composition. Addition of a nucleating agent will accordingly increase the crystallinity of the polyester phase, which results in an increased heat resistance. The composition may comprise from 0.01 to 5 wt. % by weight of nucleating agent(s).
The compositions can be manufactured by various methods known in the art. For example, polycarbonate, polyester, and other components are first blended, optionally with any fillers or additives, in a high-speed mixer or by hand mixing. The blend is then fed into the throat of a twin-screw extruder via a hopper. Alternatively, at least one of the components can be incorporated into the composition by feeding it directly into the extruder at the throat and/or downstream through a side feeder, or by being compounded into a masterbatch with a desired polymer and fed into the extruder. The extruder was set with barrel temperatures between 150° C. and 260° C. The extrudate can be immediately cooled in a water bath and pelletized. The pellets so prepared can be one-fourth inch long or less as desired. Such pellets can be used for subsequent molding, shaping, or forming.
Shaped, formed, or molded articles comprising the compositions are also provided. The compositions can be molded into articles by a variety of methods, such as injection molding, extrusion, and thermoforming. Some example of articles include automotive and vehicular body panels such as bumper covers and bumpers or a housing for electrical equipment.
Accordingly, the present invention relates to an article comprising or consisting of the composition disclosed herein. More in particular, the present invention relates to vehicular body parts or for housing of electrical equipment comprising or consisting the composition disclosed herein. Likewise, the present invention relates to a vehicle or an electrical equipment comprising said vehicular body part or said housing. The present invention relates to the use of the composition disclosed herein for the manufacture of an article of manufacture, such as an automotive part.
In accordance with the invention the composition comprises at least 30 wt. % aromatic polycarbonate and at most 70 wt. % of polyester comprising poly(ethylene terephthalate).
The amount of polycarbonate is preferably from 30 wt. %-90 wt. % such as from 55 wt. %-70 wt. % and the amount of polyester is preferably from 10-70 wt. % such as from 30 wt. %-50 wt. %.
In an aspect, it is preferred that the monovalent ionomer is produced by neutralizing all or part of the carboxylic acid using a monovalent ion, preferably selected from alkali metal ions, more preferably from sodium or potassium.
For the avoidance of doubt the skilled person will understand that the total weight of the composition will represent 100 wt. % and that any combination of materials which would not form 100 wt. % in total is unrealistic and not according to the invention. Thus, the total of the components making up the thermoplastic composition disclosed herein is 100 wt. %.
The present invention will now be further elucidated based on the following non-limiting examples.
The examples were made by extruding on a WP 25 millimeter (mm) co-rotating intermeshing twin-screw extruder having L/D of 41. The components of the compositions and their source are listed in Table 1. All components were dry-mixed and added to the throat of the extruder. The extruder was set with barrel temperatures between 150° C. and 260° C. The material was run maintaining torque of 55-60% with a vacuum of 100 millibar (mbar)-800 mbar applied to the melt during compounding. The composition was pelletized after exiting the die head.
All samples were molded via injection molding with the molding machine set from 40-280° C. and mold set at 100° C.
The amounts in Table 2 are in weight percent based on the total weight of the composition. In all the examples, the total amount of components, equals 100 weight percent. Table 2 shows that the composition comprising the Na+ ionomer impact synergist surprisingly shows improved low temperature (at −20° C. and −30° C) impact resistance property, without compromising on the thermal properties as demonstrated by HDT, VST, Tg results. When comparing C1 with E1 & E2, it is observed there is an increase of at least two times in the low temperature impact resistance property resulting from the addition of the Na+ ionomer impact synergist. E3 & E4 shows similar experiments with lower and higher concentrations of the ionomers respectively.
E2 and E5 demonstrate the properties of the composition comprising the Na+ ionomer and the Zn++ ionomer impact synergists respectively. Comparing CE1 & E2 to E3, it can be seen that presence of Zn++ ionomer does not improve the low temperature impact properties as shown in Table 3.
E6 and E7 demonstrate the use of different types of known nucleating agents to improve heat properties of PC/PET composition as shown by higher VST and HDT compared to CE1. However, these nucleating agents in E6 and E7 do not show any improvement in low temperature impact properties.
In E8 and E9, nucleating agents are added into the PC/PET composition comprising the
Na+ ionomer impact synergist. No significant improvement in low temperature impact properties is observed, although improvement in heat properties are achieved.
| Number | Date | Country | Kind |
|---|---|---|---|
| 21156855.5 | Feb 2021 | EP | regional |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/EP2022/051019 | 1/18/2022 | WO |
