Polymer composite materials with low VOC emissions

Abstract

The thermoplastic composition comprises at least one thermoplastic resin such as polybutylene terephthalate (PET), polyethylene terephthalate (PET), thermoplastic polyester elastomer (TPEE), or a combination of two or more of these; an additive that is a weak acid containing phosphorus, such as dihydrogen phosphate; and optionally an inorganic filler such as reinforcing fibers. Compared to pure thermoplastic resins, the thermoplastic composition exhibits a reduction in the emission levels of VOCs such as tetrahydrofuran (THF), particularly during heating, for example, during heating in melt processing.

Description

Technical Field

[0001] The present invention relates to a thermoplastic composition having low VOC emissions and excellent mechanical properties.

Background Art

[0002] To more fully explain the state of the art to which this invention pertains, numerous patents, patent applications, and publications are cited in this description. The entire disclosure of each of these patents, patent applications, and publications is hereby incorporated by reference into this specification.

[0003] Polybutylene terephthalate (PBT) is an engineering thermoplastic resin that is excellent in mechanical, chemical, electrical, and physical properties, and has thus been widely used in various applications such as automotive parts and consumer electronics.

[0004] Oligomers in PBT resin decompose, thereby generating tetrahydrofuran (THF) gas when heated in the molten state, for example, during processing steps such as molding or extrusion. The generation of THF gas can cause problems such as voids in the molded parts and adversely affect the mechanical properties. Resins containing PBT are particularly prone to discharging THF within the first week after molding. The generation of THF gas is promoted when the resin or article experiences high-temperature conditions. In consumer applications such as inside electronics or automobiles, this gas generation will not be tolerated by consumers.

[0005] Furthermore, many countries have legally established strict emission limits for VOCs. To comply with these domestic laws and regulations, the automotive industry has developed emission requirements that depend on the results of a number of test procedures. Therefore, automotive OEMs have initiated relevant specifications for low VOC emissions inside vehicles.

[0006] For at least these reasons, the development of PBT with low THF emissions is important for consumer comfort and also for consistency with environmental health and safety principles.

[0007] Efforts are also being made to reduce VOC emissions from polymer compositions. For example, U.S. Patent Application Publication 2009 / 0039557 describes a method for producing low-emission molded articles from thermoplastic molded compositions containing PBT, wherein the mold includes one or more vents for the release of volatile contents from the heated molded composition.

[0008] U.S. Patent No. 8,148,489, issued to Peacock et al., describes a method for reducing organic carbon emissions from resins containing PBT blocks by adding a compound that inactivates a titanium catalyst after polymerization to the resin.

[0009] European Patent No. 683201 describes a modified polybutylene terephthalate resin that reduces the amount of gases such as THF generated during high-temperature supply. In this modification, a sulfonic acid compound is added to the PBT before the polycondensation is completed. [Prior art documents] [Patent Documents]

[0010] [Patent Document 1] U.S. Patent Application Publication No. 2009 / 0039557 [Patent Document 2] U.S. Patent No. 8,148,489 [Patent Document 3] European Patent No. 683201 [Overview of the project] [Problems that the invention aims to solve]

[0011] Nevertheless, there remains a need to reduce VOC emission levels from polymer materials, especially when otherwise consumers are expected to be exposed to harmful chemicals such as THF. [Means for solving the problem]

[0012] Therefore, polymer compositions having low VOC emission levels, for example, low THF emission levels, are provided herein. The polymer composition comprises a polymer and a weak acid containing a phosphorus element. Preferably, the polymer comprises PBT and the weak acid comprises a dihydrogen phosphate.

[0013] Furthermore, a method is provided for reducing the VOC emission level of a polymer composition, and in particular the THF emission of a PBT composition, by adding a weak acid containing phosphorus to the composition, preferably during melt processing, for example, during the mixing process. [Brief explanation of the drawing]

[0014] [Figure 1] Figure 1 is a graph showing the THF emission level as a function of the weak acid concentration in the polymer composition of the present invention. [Modes for carrying out the invention]

[0015] Polymer compositions having low THF emission levels are described herein. The composition comprises a polymer and a weak acid containing a phosphorus element, such as a dihydrogen phosphate. The polymer is preferably a polymer containing PBT having an esterified 1,4-butanediol terminal group.

[0016] While I don't want to be bound by theory, I hypothesized that 1,4-butanediol is a product of deesterification by hydrolysis of a PBT-containing polymer, forming a polymer with acid-terminated groups. 1,4-butanediol further reacts to form THF.

[0017] Although not wishing to be bound by theory, a further hypothesis was put forward that in the first step of the dehydration reaction, a weak acid protonates the hydroxy group of the butanediol end group to form a butenol end group. The butenol end group is expected not to react further to form THF, even if it has been removed by de-esterification. Further, since butenol is a non-volatile liquid, it does not affect the overall VOC emissions of the polymer composition.

[0018] Polymers suitable for use in polymer compositions include polyethylene terephthalate (PET); polybutylene terephthalate (PBT); copolyether ester elastomers having PBT or PBT segments; co-PBT (i.e., PBT in which a portion of 1,4-butanediol is replaced with, for example, one or more other diols, such as aliphatic, cycloaliphatic (e.g., 1,4-cyclohexanedimethanol), or aromatic diols (e.g., 2,2-bis[4-(hydroxyethoxyphenyl)]-propane), or PBT in which the terephthalate group is replaced with the residue of another diacid, such as isophthalic acid or adipic acid), and one or more polymers selected from the group consisting of blends of any two or more of these.

[0019] Preferred polymers include one or more polymers selected from the group consisting of PBT, co-PBT, PET, PBT / PET alloys, and copolyether ester elastomers having PET or PBT segments.

[0020] More preferred polymers include one or more polymers selected from the group consisting of PBT, co-PBT, and copolyether ester elastomers having PBT segments.

[0021] A more preferred polymer is polybutylene terephthalate (PBT). Suitable PBT polymers are described in U.S. Patent No. 8,148,489 issued to Peacock et al.

[0022] Suitable PBT polymers are commercially available from DuPont Specialty Polymers USA, LLC under the trademark Crastin®. Suitable PET polymers are commercially available from DuPont Specialty Polymers USA under the trademark Rynite®.

[0023] Suitable thermoplastic copolyether esters are described in International Publication No. 2021 / 257534 by Karayianni. In addition, suitable thermoplastic copolyether esters are available under the trademark Hytrel® (DuPont Specialty Polymers USA, Wilmington, Delaware), and also under the trade names Arnitel® (DSM Engineering Materials, available from Evansville, Indiana), Riteflex® (Celanese Corporation, Florence, Kentucky (formerly Ticona)).

[0024] The polymer composition may contain 26.1 to 99.9 wt% of one or more polymers; preferably, 59 to 99.7 wt%; more preferably 69.5 to 99.7 wt% of one or more polymers. The weight percentages are based on the total weight of the polymer composition. Further, the weight percentages are complementary, i.e., the sum of the weight percentages of the components of the polymer composition is 100 wt%.

[0025] The polymer composition further comprises a weak acid containing one or more phosphorus elements. Suitable weak acids containing phosphorus elements have, for example, the following structures:

Chemical formula

[0026] In the formula, R may be substituted with H, OH, or any other C. 1~20 Alkyl, optionally substituted C 2~20 Alkylene, C may be optionally substituted. 6~10 The aryl group may be optionally substituted with C. 1~20 Alkyloxy, polyoxy(C 2~4 ) Alkylene, and optionally substituted C 6~20 The aryloxy is selected from the aryloxy group, M is selected from the cations of H, Na, K, Ca, Mg, or Al, and n is the cation charge and the number of weak acid anions in the salt. However, if R is OH, then M is not H.

[0027] More preferable weak acids containing phosphoric acid components include, but are not limited to, dihydrogen phosphates and phenylphosphonates.

[0028] Weak acids containing suitable phosphoric acid components are commercially available from numerous sources, for example, from Sigma-Aldrich in Burlington, Massachusetts.

[0029] The polymer composition may contain a weak acid containing 0.5 to 5 wt% of one or more phosphoric acid components, preferably 1 to 3 wt%, more preferably 1.5 to 2 wt% of one or more phosphoric acid components. The weight percentage is based on the total weight of the polymer composition and is complementary to the weight percentages of the other components of the polymer composition.

[0030] The polymer compositions disclosed herein may further contain other additives, such as colorants, antioxidants, UV stabilizers, UV absorbers, heat stabilizers, lubricants, viscosity modifiers, nucleating agents, plasticizers, mold release agents, scratch and blemish correctors, impact modifiers, emulsifiers, fluorescent whitening agents, antistatic agents, acid adsorbents, odor adsorbents, hydrolysis inhibitors, antibacterial agents, density modifiers, reinforcing fillers, thermally conductive fillers, flame retardant fillers, glass fibers, conductive fillers, coupling agents, end-capping reagents, and combinations of two or more of these. Based on the total weight of the polymer compositions disclosed herein, such additional additives may be present at levels of about 0.005 to 30 wt%, or about 0.01 to 25 wt%, or about 0.02 to 20 wt%.

[0031] Examples of preferred optional additives, but not limited to these, include lubricants such as RADIA 7176, LOXIOL VPG861, LICOWAX OP, and LICOLUB WE 40; antioxidants such as Irganox 1098 (CAS 23128-74-7), SONGNOX 1010, ANOX 20, and BENNOX 1010G; stabilizers such as glycerol propoxylate; and flow modifiers such as LOXIOL P861 / 3.5, LIONON DEH-40, VORANOL 2100, and PLASTHALL 809.

[0032] Inorganic fillers are preferred optional additives. When used, inorganic fillers are preferably flame retardant fillers, and examples include, but are not limited to, aluminum hydroxide, magnesium hydroxide, red phosphorus, ammonium polyphosphate, zinc borate, antimony oxide and molybdenum compounds, and combinations of two or more flame retardant fillers.

[0033] Glass fibers are a more preferred inorganic filler. The glass fibers are preferably 4 to 30 mm long, and more preferably 4 to 7 mm long. The glass fibers are preferably E glass fibers (alkali-free glass fibers), C glass fibers (glass fibers containing a moderate amount of alkali), or A glass fibers (glass fibers with a high alkali content). E glass fibers are more preferred.

[0034] Glass fibers are preferably coated with a coupling agent to enhance their performance as a reinforcing material. The general structural formula of some preferred coupling agents is represented as R-Si(OR')3, where R is a functional group that interacts with the adhesive or matrix; R' is usually methyl or ethyl, which is hydrolyzed upon use to produce silanetriol:Si(OH)3. Suitable coupling agents include, but are not limited to, KH-550, KH-560, and KH-570.

[0035] Suitable glass fibers are commercially available from Taishan Fiberglass Co., Ltd. in Tai'an City, Shandong Province, China.

[0036] The polymer composition may contain 5 to 50 wt% of one or more optional inorganic fillers, such as flame retardant fillers and glass fibers, preferably 15 to 45 wt%; more preferably 20 to 40 wt% of inorganic fillers. The weight percentages are based on the total weight of the polymer composition and are complementary to the weight percentages of the other components of the polymer composition.

[0037] In this invention, PBT with various viscosities is used. The THF discharge rate under the same conditions differs based on the different viscosities. The results show that this method is effective for PBT with various viscosities. A preferred viscosity is 0.5 dl / gr to 1.5 dl / gr, a desirable viscosity is 0.7 dl / gr to 1.2 dl / gr, and a more preferred viscosity is 0.8 dl / gr to 1.1 dl / gr.

[0038] Polymer compositions can be produced by any conventional melt-blending method, such as the method described above using a twin-screw extruder.

[0039] Furthermore, articles comprising polymer compositions are provided herein. Preferred and favorable weak acids and other components of the polymer composition, preferred and favorable amounts of the weak acids and other components, and preferred and favorable methods for forming the polymer composition for use in articles are as discussed above with respect to the polymer composition itself.

[0040] Examples of items, though not limited to these, include drive housings for wind lifters, drive housings for seat adjustments, various switches and boxes, and steering angle sensors.

[0041] Articles can be formed by conventional methods, such as injection molding, blow molding, or extrusion. A more preferred method of formation is injection molding.

[0042] Furthermore, a method for reducing THF emissions from a polymer composition is provided. This method comprises the steps of providing other components of the polymer composition and adding a weak acid containing phosphorus to the other components. Suitable and preferred phosphorus-containing weak acid and other components of the polymer composition for use in this method, suitable and preferred amounts of the phosphorus-containing weak acid and other components, and suitable and preferred processes for forming the polymer composition are as discussed above with respect to the polymer composition itself. Preferably, the phosphorus-containing weak acid is added to the polymer composition during the mixing process.

[0043] VOC emissions from polymer compositions and articles can be further reduced by applying a vacuum to the molten polymer during the mixing or molding process to collect VOCs such as THF.

[0044] The following embodiments are provided to illustrate the present invention in more detail. These embodiments illustrate currently anticipated preferred modes for carrying out the present invention and are intended to be illustrative and not limiting. [Examples]

[0045] 1) Molding conditions: The examples and comparative examples were molded into 60 × 60 × 2 mm and 60 × 60 × 1 mm plates under the following conditions: Melting temperature: 250℃, 280℃ Molding temperature: 80℃ Holding time: 5 minutes.

[0046] 2) Gas emission test: The degree of volatile organic compound (VAF) emissions from the tested polymer compositions was determined according to the method described in the German Association of the Automotive Industry (Verband der Automobilindustrie) [VDA] standard VDA277. Specifically, this refers to THF emissions that commonly occur immediately after molding, extrusion, or formation of polymer compositions. THF emissions from PBT can be measured using gas chromatography (GC), for example, gas chromatography-mass spectrometry (GC-MS).

[0047] After forming the plates, they were stored in sealed aluminum foil bags. To perform the analysis, the plates were removed from the bags, cut into small pieces, and then tested by GC / MS according to the VDA277 standard. In this method, the GC / MS settings were as follows: Stove temperature program GC: Isothermal heating at 50℃ for 3 minutes Heating at 200°C at a rate of 12K / min Isothermal heating at 200°C for 4 minutes Injector temperature: 200℃ Detector temperature: 250℃ Split ratio: approx. 1:20 Carrier gas: Helium Central carrier gas velocity: approximately 22-27 cm / second.

[0048] Calibration: 2,6-di-tert-butyl-4-methylphenol (BHT) should exhibit a retention time of less than 16 minutes when performed under the same conditions as the discharge from the polymer composition.

[0049] THF emissions were measured for compositions containing three types of PBT polymers with different viscosities (i.e., different molecular weights).

[0050] 3) The intrinsic viscosity (IV) of PBT was determined according to ASTM D2857.

[0051] 4) Material: Polybutylene terephthalate with an IV of PBT-1:0.7 dl / gr was obtained from CHANG CHUN PLASTICS CO.LTD.

[0052] Polybutylene terephthalate with an IV of 0.9 dl / gr for PBT-2 was obtained from CHANG CHUN PLASTICS CO.LTD.

[0053] Polybutylene terephthalate with an IV of 1.0 dl / gr for PBT-3 was obtained from CHANG CHUN PLASTICS CO.LTD.

[0054] NaH2PHO4 powder was obtained from NAGASE & CO. LTD.

[0055] The glass fiber was obtained from TANSHAN FIBERGLASS CO.LTD. The grade name is S-1HM436S.

[0056] In Comparative Examples CE1-CE6 and Examples E1-E12, the polymer compositions (the weight percentages of non-PBT components are listed in Table 1) were prepared by mixing in an extruder. The barrel temperature was set to approximately 250°C and the screw speed to approximately 350 rpm. After removing the blended composition from the extruder, it was cooled with water, cut into resin pellets, and then dried in an electric blast dryer at a temperature of 90°C for approximately 15 hours.

[0057] The dried resin pellets obtained in Comparative Examples CE1-CE4 and Examples E1-E8 were injection molded into 60×60×2mm plaques using a melting temperature of 250°C; Comparative Examples CE5 and Examples E9-E10 were injection molded into 60×60×1mm plaques using a melting temperature of 280°C; and Comparative Examples CE6 and Examples E11-E12 were injection molded into 60×60×2mm plaques using a melting temperature of 280°C. The discharge performance of the plaques was measured and summarized in Tables 1, 2, and 3. In these tables, the term "balance" refers to the difference between the total and 100 wt% of the weight percentage of other components in the examples and comparative examples.

[0058] Furthermore, for each sample, tensile stress and tensile strain at fracture were measured according to ISO 527-2:2012, bending stress was measured according to ISO 178, and N-Charpy impact was measured according to ISO 179-1. The results are summarized in Table 1.

[0059] Table 1 lists the test results for different filler amounts of NaH2PO4 (E1, E5-E8). The graph in Figure 1 shows that the optimized range for filler amounts is greater than 0.3 wt%, greater than 0.5 wt%, or approximately 3 wt%. [Table 1] [Table 2] [Table 3]

[0060] While certain preferred embodiments of this invention have been described and illustrated above, the invention is not intended to be limited to such embodiments. Various modifications can be made without departing from the scope and essence of the invention, as described in the following claims.

Claims

1. a) At least one thermoplastic resin selected from the group consisting of polybutylene terephthalate (PBT), polyethylene terephthalate (PET), and polymers containing copolymerized PBT components; b) A weak acid containing a phosphorus element having the following structure: 【Chemistry 1】 (In the formula, R may be substituted with H, OH, or any other C.) １～２０ Alkyl, optionally substituted C ２～２０ Alkylene, C may be optionally substituted. ６～１０ The aryl group may be substituted with any other C. １～２０ Alkyloxy, polyoxy (C ２～４ ) Alkylene, and optionally substituted C ６～２０ Selected from the group consisting of aryloxys; M is selected from the group consisting of cations of H, Na, K, Ca, Mg, and Al; n is the cation charge of M; However, if R is OH, then M is not H); and c) Other additives A thermoplastic composition containing the following:

2. The thermoplastic composition according to claim 1, wherein the at least one thermoplastic resin includes PBT.

3. The thermoplastic composition according to claim 1, wherein the at least one thermoplastic resin comprises a thermoplastic copolyether ester having a copolymerized PBT component.

4. The thermoplastic composition according to claim 1, wherein the at least one thermoplastic resin is present in an amount of 10 wt% to 99.9 wt% based on the total weight of the thermoplastic composition.

5. The thermoplastic composition according to claim 1, wherein the weak acid comprises a dihydrogen phosphate or a phenylphosphonate.

6. The thermoplastic composition according to claim 1, wherein the weak acid comprises sodium dihydrogen phosphate, potassium dihydrogen phosphate, or both sodium dihydrogen phosphate and potassium dihydrogen phosphate.

7. The thermoplastic composition according to claim 1, wherein the weak acid is present in an amount of 0.01 to about 3 wt% based on the total weight of the thermoplastic composition.

8. The thermoplastic composition according to claim 1, wherein the weak acid is present in an amount of 0.01 to about 2 wt% based on the total weight of the thermoplastic composition.

9. The thermoplastic composition according to claim 1, wherein the weak acid is present in an amount of 0.01 to about 1 wt% based on the total weight of the thermoplastic composition.

10. The thermoplastic composition according to claim 1, wherein at least one inorganic filler comprises a flame-retardant filler.

11. The thermoplastic composition according to claim 1, wherein the flame-retardant filler comprises one or more fillers selected from the group consisting of aluminum hydroxide, magnesium hydroxide, red phosphorus, ammonium polyphosphate, zinc borate, antimony oxide, and molybdenum compounds.

12. The thermoplastic composition according to claim 1, wherein the optionally selected inorganic filler is a reinforcing filler.

13. The thermoplastic composition according to claim 13, wherein the reinforcing filler is selected from the group consisting of glass fibers, silica, talc, mica, carbon black, carbon fibers, aramid fibers, hollow glass spheres, glass flakes, hollow glass beads, ground glass fibers, and two or more combinations thereof.

14. The thermoplastic composition according to claim 1, wherein an optional inorganic filler is present in an amount of 0.01 to about 50 wt% based on the total weight of the thermoplastic composition.

15. The thermoplastic composition according to claim 1, further comprising one or more other additives selected from the group consisting of lubricants, plasticizers, colorants, and antioxidants.

16. A method for reducing VOC emissions from polymer compositions, a) A step of providing a polymer composition comprising at least one thermoplastic resin selected from the group consisting of polybutylene terephthalate (PBT), polyethylene terephthalate (PET), and polymers containing copolymerized PBT components, and optionally an inorganic filler; and b) A step of adding a weak acid containing phosphorus to the polymer composition. The above method, including.

17. c) A step of melting the polymer composition; and d) A step of collecting VOCs emitted by the molten polymer composition by applying a vacuum. The method according to claim 17, further comprising:

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