A polyester composition and its preparation method and application

Abstract

The present invention relates to a polyester composition and a preparation method and application thereof, the components comprising: PBT resin, compound resin flat glass fiber, ester plasticizer, carbonate, and other additives. The polyester composition of the present invention can simultaneously meet the conditions of being immersed in a 10% NaOH solution at 60°C for 200 hours, with a tensile strength performance retention rate of ≥60%, a performance retention rate of unnotched impact strength of ≥40%, and a 2.5mm sample laser transmittance of ≥30%. The composition is particularly suitable for the fields of automobiles and electronic appliances.

Description

Technical Field

[0001] The invention belongs to the field of engineering plastics, and particularly relates to a polyester composition and a preparation method and application thereof. Background Art

[0002] Polybutylene terephthalate (PBT) is widely used in the fields of automobiles, electronics, and construction due to its excellent mechanical strength, solvent resistance, wear resistance, electrical insulation, dimensional stability, and other characteristics. For example, in the automotive field, it can be used for connectors, distributors, ignition coils, sensors, control units, etc.; in the electronics and electrical field, it can be used for connectors, switch parts, relays, coil components, etc. In the construction field, it can be used for sanitary parts and concrete embedded bolts. Among them, some plastic parts with complex structures and shapes cannot be processed and formed in one go, and adhesives, screw fixation, snap fit, hot plate welding, ultrasonic welding, and other methods are required to join multiple formed parts.

[0003] Compared with traditional plastic welding processes, laser welding is an efficient and precise welding method that uses a high-energy-density laser beam as a heat source. Its rapid heating and cooling rates can significantly reduce the vibration stress and thermal stress of products. In addition, the laser welding process is stable, and the surface and internal quality of the weld are very good. It can be welded in a vacuum, air or other gas environment, and has low requirements for the welding medium. It can also be welded through glass or other materials that are transparent to the light beam. Due to its unique advantages, laser welding is increasingly used in processes that require secondary welding.

[0004] However, compared with amorphous materials such as polycarbonate resin and polystyrene resin, polyester resin as a semi-crystalline resin has relatively low laser transmittance, so the processing condition window is narrow. When welding, it is necessary to increase the laser power or irradiation rate, or reduce the thickness of the molded part of the laser irradiation part, in order to achieve a good bonding effect. However, increasing the laser power or irradiation rate may cause the surface of the material to burn and whiten, and the welding strength decreases at the same time. At present, there are various known methods for improving the laser transparency of PBT. For example, CN102892819B discloses laser transparent polyester, which relates to a thermoplastic molded body for preparing laser transparent molded parts. The thermoplastic molded body described in the patent contains the following main components. Although the laser transmittance of PBT materials can be improved by adding alkaline substances such as Na2CO3, K2CO3, NaHCO3, and KHCO3, the ester group of the material is easily accelerated to hydrolyze under alkaline conditions, causing the material to deteriorate rapidly and cannot meet the use requirements. Even worse conditions are that the material may also be used in alkaline environments such as snow melting agents, toilet cleaners, bathroom cleaners, bleaching agents, and cement. Currently, the existing technology cannot meet the requirements of both alkali resistance and high light transmittance. Summary of the invention

[0005] In view of the defects of the prior art, the technical problem to be solved by the present invention is to provide a polyester composition and a preparation method and application thereof.

[0006] A polyester composition of the present invention comprises, by weight:

[0007]

[0008] The composite resin is styrene-acrylonitrile SAN resin and styrene-maleic anhydride SMA resin, wherein the mass ratio of SAN resin to SMA resin is (3-6):1.

[0009] The terminal carboxyl concentration of the PBT resin is not greater than 15 mol / t.

[0010] Furthermore, the terminal carboxyl concentration of the PBT resin is 0.01-15 mol / t.

[0011] Preferably, the mass ratio of the SAN resin to the SMA resin is (4-5):1.

[0012] The preferred mass ratio of SAN resin to SMA resin ensures that the polyester composition has both good laser transmittance and mechanical property retention rate.

[0013] The aspect ratio of the cross section of the flat glass fiber is 2-6:1.

[0014] The ester plasticizer is at least one of a diester plasticizer and a triester plasticizer.

[0015] Preferably, the diester plasticizer is a diester plasticizer formed by at least one of phthalic acid, terephthalic acid, adipic acid, maleic acid, azelaic acid, sebacic acid and their anhydrides and at least one alcohol selected from aliphatic alcohols, alicyclic alcohols and aromatic alcohols.

[0016] Further preferably, the diester plasticizer is one or more of butyl benzyl phthalate, dilauryl phthalate, disundecyl phthalate, diheptyl phthalate, dicyclohexyl phthalate, diisodecyl phthalate, dioctyl phthalate, dioctyl adipate, diisodecyl adipate, di(butoxyethyl) adipate, bis-2-ethylhexyl azelate, bis-2-ethylhexyl maleate, dibutyl maleate, dioctyl sebacate, and dibutyl sebacate.

[0017] Preferably, the triester plasticizer is a triester plasticizer formed by at least one acid selected from citric acid, trimellitic acid, phosphoric acid and their anhydrides and at least one alcohol selected from aliphatic alcohols, alicyclic alcohols and aromatic alcohols.

[0018] Further preferably, the triester plasticizer is one or more of triethyl citrate, tributyl citrate, trioctyl citrate, tributyl trimellitate, tri(2-ethylhexyl) trimellitate, tricresyl phosphate, tri(isopropylphenyl) phosphate, trioctyl phosphate, tri(butoxyethyl) phosphate, tri(β-chloropropyl) phosphate, triphenyl phosphate, and octyl diphenyl phosphate.

[0019] Preferably, the carbonate is one or more of sodium carbonate, sodium bicarbonate, potassium carbonate and potassium bicarbonate.

[0020] Preferably, the polyester composition further contains 0.5-5 parts of other additives, and the other additives are one or more of light stabilizers, antioxidants, and lubricants.

[0021] Furthermore, the other auxiliary agents are 0.6-2 parts.

[0022] Furthermore, the light stabilizer includes but is not limited to Cyasorb UV-3346 light stabilizer, Uvinul4050H light stabilizer, Tinuvin622 light stabilizer and Chimassor b944 light stabilizer.

[0023] Furthermore, the lubricant includes, but is not limited to, one or more of silicone, oxidized polyolefin wax, hyperbranched polyester, aliphatic fatty acid ester or ethylene-acrylic acid copolymer.

[0024] Further, the antioxidant includes but is not limited to any one or more of N,N'-bis-(3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionyl)hexanediamine (antioxidant 1098), tris[2,4-di-tert-butylphenyl]phosphite (antioxidant 168), pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate (antioxidant 1010), bis(2,4-dicumylphenyl)pentaerythritol diphosphite (antioxidant S9228) or phosphite antioxidants.

[0025] Preferably, by weight, the components include:

[0026]

[0027] A method for preparing the polyester composition of the present invention comprises:

[0028] The components are weighed according to the proportion, mixed evenly and then added into a twin-screw extruder for melt mixing and extrusion granulation to obtain the polyester composition.

[0029] Preferably, the extrusion granulation temperature is 220-280°C.

[0030] The polyester composition of the present invention is used in automobiles or electronic appliances, such as ignition coils, electronic control boxes, sensors, connectors, etc.

[0031] The polyester composition of the present invention adds compounded resins SAN resin and SMA resin to PBT. On the one hand, the SMA resin improves the compatibility of the PBT phase and the SAN phase, reduces the size of the two phases, and is conducive to obtaining good laser transmission. At the same time, the introduction of the benzene ring increases the alkali resistance of the system. On the other hand, the maleic anhydride group of SMA can react with the terminal carboxyl group of PBT to slow down the breakage of the ester group in an alkaline environment. At the same time, the ester plasticizer plays an alkali resistance improvement role, can block the entry of alkaline solutions in the external environment, effectively protects the matrix, eliminates the deterioration effect of carbonate as a laser transmission improver on the mechanical properties of the material, and greatly improves the alkali resistance of the material compared with the traditional polycarbodiimide anti-hydrolysis agent.

[0032] Beneficial Effects

[0033] The polyester composition of the present invention can simultaneously meet the conditions of being immersed in a 10% NaOH solution at 60° C. for 200 hours, with a tensile strength performance retention rate of ≥60%, a notched impact strength performance retention rate of ≥40%, and a 2.5 mm sample laser transmittance of ≥30%. The composition is particularly suitable for the automotive and electronic and electrical fields. DETAILED DESCRIPTION

[0034] The present invention will be further described below in conjunction with specific embodiments. It should be understood that these embodiments are only used to illustrate the present invention and are not intended to limit the scope of the present invention. In addition, it should be understood that after reading the content taught by the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms fall within the scope limited by the appended claims of the application equally.

[0035] 1. Source of raw materials:

[0036] PBT resin: PBT GX121J, Yizheng Petrochemical, terminal carboxyl concentration is 9 mol / t

[0037] Flat glass fiber: glass fiber TFG-3.0-T436, cross-section length-width ratio 4:1; Shandong Taishan Glass Fiber Co., Ltd.;

[0038] SAN resin: SAN NF2200AK, Taiwan Formosa Chemical Corporation;

[0039] SMA resin: SMA-725K, Jiaxing Huawen Chemical Co., Ltd.;

[0040] PTW: ethylene-acrylate-glycidyl methacrylate, DuPont;

[0041] Ester plasticizer-1: trioctyl citrate, West Asia reagent;

[0042] Ester plasticizer-2: Diundecyl phthalate, Beijing Aomijiade Pharmaceutical Technology Co., Ltd.

[0043] Ester plasticizer-3: Dioctyl adipate, Shandong Kexing Chemical Co., Ltd.

[0044] Hydrolysis resistance agent: polycarbodiimide Stabaxol P400, Rhein Chemie, Germany

[0045] Carbonate: Sodium carbonate: Aladdin reagent

[0046] Other additives: The mass ratio of antioxidant 1098 and antioxidant 168 is 1:1;

[0047] Compound resin-1: The mass ratio of SAN resin and SMA resin is 4:1;

[0048] Compound resin-2: The mass ratio of SAN resin and SMA resin is 5:1;

[0049] Compound resin-3: The mass ratio of SAN resin and SMA resin is 3:1;

[0050] Compound resin-4: The mass ratio of SAN resin and SMA resin is 6:1;

[0051] Compound resin-5: The mass ratio of SAN resin and SMA resin is 1:1;

[0052] Compound resin-6: The mass ratio of SAN resin and SMA resin is 8:1;

[0053] Compound resin-7: The mass ratio of SAN resin and PTW resin is 4:1;

[0054] The sodium carbonate and other additives used in the parallel examples and comparative examples are all the same commercially available products.

[0055] 2. Preparation methods of embodiments and comparative examples

[0056] Weigh each component according to the ratio, mix them evenly and then add them into a twin-screw extruder for melt mixing and extrusion granulation to obtain the polyester composition. The extrusion granulation temperature is 220-280°C.

[0057] 3. Test standards and methods

[0058] Mechanical properties test:

[0059] Tensile strength: tested according to ISO527-2-2012, tensile rate is 10mm / min, test conditions: 23℃, 50%RH;

[0060] Unnotched impact strength: tested in accordance with ISO 179-1-2010, specimen size 80 mm × 10 mm × 4 mm, test conditions: 23°C, 50% RH.

[0061] Alkali resistance test: The injection molded tensile specimens and non-notched impact strength specimens were placed in a 10% by mass concentration NaOH solution, soaked at 60°C for 200 hours, taken out, and placed in a 23°C / 50% RH environment for 24 hours before mechanical properties testing. The performance retention rate was calculated compared with the original performance.

[0062] The performance retention rate is calculated as follows: Px / P0×100%, where P0 is the initial mechanical property and Px is the mechanical property after alkali resistance test treatment.

[0063] Laser transmittance test:

[0064] The samples were molded into 80mm×50mm×2mm samples (thickness 2mm) using an injection molding machine, with a barrel temperature of 280°C and a mold temperature of 120°C. The transmittance at the center of the sample was measured using a near infrared spectrometer (wavelength 900-1700nm, Ocean Optics NIRQuest spectrometer), and the transmittance at a wavelength of 1064nm was measured.

[0065] Table 1 is the ratio of the embodiment (parts by weight)

[0066]

[0067] Table 2 Example ratio (weight parts)

[0068]

[0069]

[0070] Table 3 Comparative Example Proportions (parts by weight)

[0071]

[0072] Table 4 is the performance data of the embodiment

[0073]

[0074] Table 5 Performance data of the embodiment

[0075]

[0076]

[0077] Table 6 Comparative Example Performance Effect Data

[0078]

[0079] Examples 1, 11-13 and Comparative Examples 1-5, 7, 8 and 12 illustrate that only when the content of the ester plasticizer is fixed and the SAN resin and the SMA resin are compounded and the ratio is within a specific range can the requirements of tensile strength retention rate ≥ 60%, unnotched impact strength retention rate ≥ 40% and 2 mm sample laser transmittance ≥ 30% be simultaneously met.

[0080] Example 1 and Comparative Examples 6 and 11 illustrate that ester plasticizers can significantly improve the alkali resistance of materials compared to traditional anti-hydrolysis agents, and have less negative impact on laser transmittance.

[0081] Examples 1, 14-16 and Comparative Examples 9-10 show that when the proportion of the compounded resin is fixed and the proportion of the ester plasticizer is 0.5-6 parts, the requirements of tensile strength retention rate ≥ 60%, unnotched impact strength retention rate ≥ 40% and 2mm sample laser transmittance ≥ 30% can be met.

[0082] Examples 1-16 and Comparative Examples 6 and 12 illustrate that the compounded resin and ester plasticizer must exist simultaneously in the system and the ratio must be within a specific range to simultaneously meet the requirements of tensile strength retention rate ≥ 60%, unnotched impact strength retention rate ≥ 40% and 2mm sample laser transmittance ≥ 30%.

Claims

1. A polyester composition, characterized in that By weight, the components include: The composite resin is SAN resin and SMA resin, wherein the mass ratio of SAN resin to SMA resin is (3-6):1; wherein the ester plasticizer is at least one of a diester plasticizer or a triester plasticizer; The diester plasticizer is a diester plasticizer formed by at least one of phthalic acid, terephthalic acid, adipic acid, maleic acid, azelaic acid, sebacic acid and their anhydrides and at least one alcohol selected from aliphatic alcohols, alicyclic alcohols and aromatic alcohols; The triester plasticizer is a triester plasticizer formed by at least one acid selected from citric acid, trimellitic acid, phosphoric acid and their anhydrides and at least one alcohol selected from aliphatic alcohols, alicyclic alcohols and aromatic alcohols.

2. The polyester composition according to claim 1, characterized in that: The terminal carboxyl concentration of the PBT resin is not greater than 15 mol / t.

3. The polyester composition according to claim 1, characterized in that: The mass ratio of the SAN resin to the SMA resin is (4-5):

1.

4. The polyester composition according to claim 1, characterized in that: The aspect ratio of the cross section of the flat glass fiber is 2-6:1; the carbonate is one or more of sodium carbonate, sodium bicarbonate, potassium carbonate and potassium bicarbonate.

5. The polyester composition according to claim 1, characterized in that: The diester plasticizer is one or more of butyl benzyl phthalate, diundecyl phthalate, dilauryl phthalate, diheptyl phthalate, dicyclohexyl phthalate, diisodecyl phthalate, dioctyl phthalate, dioctyl adipate, diisodecyl adipate, di(butoxyethyl) adipate, di-2-ethylhexyl azelate, di-2-ethylhexyl maleate, dibutyl maleate, dioctyl sebacate, and dibutyl sebacate; The triester plasticizer is one or more of triethyl citrate, tributyl citrate, trioctyl citrate, tributyl trimellitate, tri(2-ethylhexyl) trimellitate, tricresyl phosphate, tri(isopropylphenyl) phosphate, trioctyl phosphate, tri(butoxyethyl) phosphate, tri(β-chloropropyl) phosphate, triphenyl phosphate, and octyl diphenyl phosphate.

6. The polyester composition according to claim 1, characterized in that: The polyester composition further contains 0.5-5 parts of other auxiliary agents, wherein the other auxiliary agents are one or more of light stabilizers, antioxidants and lubricants.

7. The polyester composition according to claim 1, characterized in that: By weight, the components include:

8. A method for preparing the polyester composition according to claim 1, comprising: The components are weighed according to the proportion, mixed and added into a twin-screw extruder for melt mixing and extrusion granulation to obtain the polyester composition.

9. Use of the polyester composition according to claim 1 in the fields of automobiles and electronic appliances.

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