Polymer alloy, wire including polymer alloy, and accessory including wire

Abstract

To provide a polymer alloy which has high transparency, can be subjected to plastic working at normal temperature, and hardly causes whitening even when repeatedly bent SOLUTION: The polymer alloy is a polymer alloy of a polycarbonate and a polyester-based thermoplastic elastomer, wherein the weight ratio of the polycarbonate to the polyester-based thermoplastic elastomer is 90:10 to 50:50, and the polymer alloy does not have a glass transition temperature at a temperature of 140 °C or higher.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a polymer alloy, a wire comprising the polymer alloy, and an accessory comprising the wire. [Background technology]

[0002] Transparent objects with curved surfaces are sometimes used for accessories, etc. A typical example of a transparent resin is polycarbonate.

[0003] JP 2005-350641 A describes a polycarbonate resin composition containing a polycarbonate resin and at least two resin components. This resin composition has a viscosity of 2933±5 cm -1 The absorption peak appears in the range of 2965±5cm -1 The absorption peak intensity ratios that appear in the range satisfy a predetermined relationship.

[0004] JP 2023-100190 A describes a resin composition for additive manufacturing that can be used as a filament for a fused deposition modeling three-dimensional printer. The resin composition contains a polycarbonate resin, an amorphous polyester resin, and a heat-softening material. The heat-softening material is at least one of a eutectic copolymer polyester, polycaprolactone, and a polyester-based thermoplastic elastomer. The resin composition has a total light transmittance of 85% or more.

[0005] Japanese Patent Application Laid-Open Publication No. 2023-100191 describes a resin composition for additive manufacturing that can be used as a filament for a fused deposition modeling three-dimensional printer, containing a polycarbonate resin, an amorphous polyester resin, an impact modifier, and a heat softener. This resin composition contains at least one of a styrene-based thermoplastic elastomer and a core-shell impact modifier as the impact modifier, and at least one of a eutectic copolymer polyester, polycaprolactone, and a polyester-based thermoplastic elastomer as the heat softener.

[0006] Chinese Patent Publication No. 107383830 describes a PC / PETG material for three-dimensional printers, which includes polycarbonate (PC), glycol-modified polyethylene terephthalate (PETG), a toughener, a compatibilizer, a lubricant, an anti-UV agent, and a colorant. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Japanese Patent Application Laid-Open No. 2005-350641 [Patent Document 2] Japanese Patent Application Publication No. 2023-100190 [Patent Document 3] Japanese Patent Application Publication No. 2023-100191 [Patent Document 4] Chinese Patent Application Publication No. 107383830 Summary of the Invention [Problem to be solved by the invention]

[0008] For applications such as accessories, there is a need to be able to freely bend and process transparent materials using hands or simple tools (such as pliers). Glass is a typical transparent material, but glass cannot be processed without heating, making it unsuitable for the above applications. Furthermore, plastics have strong elastic properties at room temperature, and return to their original shape when bent, making them unsuitable for processing (plastic processing) by bending, twisting, or wrapping like wire. Furthermore, bending plastics can whiten, causing a loss of transparency.

[0009] An object of the present invention is to provide a polymer alloy which is highly transparent, can be plastically processed at room temperature, and is resistant to whitening even when repeatedly bent. [Means for solving the problem]

[0010] A polymer alloy according to one embodiment of the present invention is a polymer alloy of polycarbonate and polyester-based thermoplastic elastomer, in which the weight ratio of the polycarbonate to the polyester-based thermoplastic elastomer is 90:10 to 50:50, and the polymer alloy does not have a glass transition temperature at a temperature of 140°C or higher. [Effects of the Invention]

[0011] According to the present invention, a polymer alloy can be obtained which is highly transparent, can be plastically processed at room temperature, and is resistant to whitening even when repeatedly bent. [Brief explanation of the drawings]

[0012] [Figure 1] FIG. 1 is a diagram showing a schematic diagram of the screw arrangement of the twin-screw extruder used in the examples. [Figure 2] FIG. 2 is a diagram schematically showing the screw arrangement of the twin-screw extruder used in the comparative examples. DETAILED DESCRIPTION OF THE INVENTION

[0013] [Polymer alloy] A polymer alloy according to one embodiment of the present invention will be described in detail below. The polymer alloy according to this embodiment is a polymer alloy of polycarbonate and polyester-based thermoplastic elastomer, in which the weight ratio of polycarbonate to polyester-based thermoplastic elastomer is polycarbonate:polyester-based thermoplastic elastomer=90:10 to 50:50, and the polymer alloy does not have a glass transition temperature at a temperature of 140°C or higher.

[0014] The polymer alloy according to this embodiment contains a polycarbonate. The polycarbonate constituting the polymer alloy according to this embodiment is not particularly limited, and commercially available general polycarbonates can be used. Polycarbonate is a polymer having a structure containing a carbonate ester group (carbonate group). The polycarbonate constituting the polymer alloy according to this embodiment may contain an aromatic compound between the carbonate ester groups, or may not contain an aromatic compound between the carbonate ester groups. However, a polycarbonate containing an aromatic compound between the carbonate ester groups is preferred, and may be, for example, a polymer derived from 2,2-bis(4-hydroxyphenyl)propane.

[0015] The polymer alloy according to this embodiment contains a polyester-based thermoplastic elastomer (hereinafter referred to as "polyester-based TPE"). Polyester-based TPE is a block copolymer with an aromatic polyester as the hard segment and a polyether or aliphatic polyester as the soft segment. Examples of aromatic polyesters in the hard segment include polyethylene terephthalate (PET) and polybutylene terephthalate (PBT). Examples of polyethers in the soft segment include polyethylene glycol (PEG) and polytetramethylene ether glycol (PTMG). Examples of aliphatic polyesters in the soft segment include polyethylene adipate and polycaprolactone.

[0016] The polyester-based TPE constituting the polymer alloy according to the present embodiment preferably has a soft segment made of polyether, and is particularly preferably a block copolymer of PBT and polyether. The polyester-based TPE constituting the polymer alloy according to the present embodiment may be, for example, a block copolymer of PBT and PTMG.

[0017] The polymer alloy according to this embodiment does not have a glass transition temperature at a temperature of 140° C. or higher. That is, the polymer alloy according to this embodiment has a glass transition temperature of less than 140° C., or does not have an observable (clear) glass transition temperature at a temperature of at least 140° C. or higher. The glass transition temperature can be measured by a differential scanning calorimeter (DSC).

[0018] The glass transition temperature of typical polycarbonate is 147°C. By blending polyester-based TPE with polycarbonate and kneading under specific conditions, the polycarbonate and polyester-based TPE are mixed at the molecular level. As a result, a polymer alloy is obtained that has a lower glass transition temperature than polycarbonate alone (or does not have a clear glass transition temperature above 140°C). The kneading conditions are described in detail below.

[0019] If the polymer alloy has a glass transition temperature above 140°C, the polycarbonate and polyester-based TPE are not mixed properly, which reduces the elongation at break of the polymer alloy and reduces its processability.

[0020] The reason why the glass transition temperature is lower when polycarbonate and polyester-based TPE are thoroughly mixed compared to polycarbonate alone is thought to be as follows: When polyester-based TPE is thoroughly mixed into polycarbonate, the crystallinity of the polycarbonate is impaired. This means that high temperatures are not required to change the polymer alloy from a glassy to a rubbery state. As a result, the glass transition temperature is observed at a lower temperature than when polycarbonate is solely mixed. Furthermore, when polycarbonate and polyester-based TPE are extremely thoroughly mixed, the crystallinity of the polycarbonate becomes extremely low, and the glass transition temperature derived from the polycarbonate is no longer observed.

[0021] When the polymer alloy has a glass transition temperature, the upper limit of the glass transition temperature is preferably 135°C, more preferably 130°C, and even more preferably 125°C. When the polymer alloy has a glass transition temperature, the lower limit of the glass transition temperature is not particularly limited, but is, for example, 100°C, and preferably 110°C. Furthermore, when the polymer alloy has a glass transition temperature, the glass transition temperature of the polymer alloy is preferably 5°C or more lower, and more preferably 10°C or more lower, than the glass transition temperature of the polycarbonate alone contained in the polymer alloy.

[0022] The polymer alloy according to this embodiment has a weight ratio of polycarbonate to polyester-based TPE of polycarbonate:polyester-based TPE=90:10 to 50:50. If the proportion of polyester-based TPE is too low, the yield stress will not be low, and plastic processing at room temperature may not be possible. On the other hand, if the proportion of polyester-based TPE is too high, the material may become too soft or the transparency may decrease. The lower limit of the proportion of polyester-based TPE is more preferably polycarbonate:polyester-based TPE=80:20. The upper limit of the proportion of polyester-based TPE is more preferably polycarbonate:polyester-based TPE=60:40.

[0023] The polymer alloy according to this embodiment may contain a polymer other than polycarbonate and polyester-based TPE. The proportion of the polymer other than polycarbonate and polyester-based TPE in the polymer alloy according to this embodiment is preferably 10% or less by weight, more preferably 5% or less, even more preferably 2% or less, and even more preferably 1% or less by weight based on the total weight of the polymer alloy.

[0024] The polymer alloy according to this embodiment preferably has a total light transmittance of 70% or more as measured on a test piece having a thickness of 1.0 mm. The total light transmittance is measured in accordance with JIS K 7105. The total light transmittance measured on a test piece having a thickness of 1.0 mm is more preferably 75% or more.

[0025] The polymer alloy according to this embodiment preferably has a yield stress of 30 to 55 MPa. The yield stress (tensile yield strength) is measured at room temperature (23°C ± 2°C). The yield stress is the stress at the upper yield point. By setting the yield stress of the polymer alloy to 30 to 55 MPa, plastic working at room temperature becomes easier. The lower limit of the yield stress is more preferably 40 MPa. The upper limit of the yield stress is more preferably 50 MPa.

[0026] The yield stress of the polymer alloy can be adjusted by the weight ratio of polycarbonate to polyester-based TPE. By increasing the weight ratio of polyester-based TPE, the yield stress of the polymer alloy can be reduced.

[0027] The polymer alloy according to this embodiment preferably has an elongation at break of 100% or more, more preferably 150% or more. There is no particular upper limit to the elongation at break of the polymer alloy according to this embodiment, but it is, for example, 250%. The elongation at break is measured at room temperature (23°C ± 2°C). The elongation at break Eb is calculated by the following formula: Eb=(L-L0) / L0 where L is the length at the time of cutting and L0 is the initial length.

[0028] [Polymer alloy manufacturing method] The polymer alloy according to this embodiment can be produced by kneading polycarbonate and polyester-based TPE under the kneading conditions described below, which allow the polycarbonate and polyester-based TPE to be mixed at the molecular level, resulting in a polymer alloy with a lower glass transition temperature than polycarbonate alone.

[0029] Polycarbonate and polyester-based TPE are mixed in a twin-screw extruder. The screw configuration of the twin-screw extruder is provided with kneading zones containing kneading disks with an L / D ratio of 10 or more, and a reverse screw with an L / D ratio of 1 or more is provided at the end of at least one kneading zone.

[0030] The cylinder temperature in the kneading zone is 200 to 300°C, preferably 230 to 270°C. The cylinder temperature immediately after the inlet of the twin-screw extruder is 170 to 230°C, preferably 180 to 220°C.

[0031] The screw rotation speed during kneading is preferably 100 to 150 rpm. If the rotation speed is less than 100 rpm, sufficient mixing may not be achieved, and the glass transition temperature may not decrease. If the rotation speed exceeds 150 rpm, the shear stress may become too large, causing molecular chain scission, which may result in coloration of the polymer alloy or deterioration (specifically, a decrease in elongation at break).

[0032] The output of the twin-screw extruder is preferably 1 to 2 kg / h. The shear energy applied to the resin per unit weight is inversely proportional to the output.

[0033] The feed rate of the raw resins (polycarbonate and polyester-based TPE) is adjusted so that the filling rate in the twin-screw extruder is in the range of 30 to 60%. The filling rate is the value obtained by weighing the resin that comes out from the time the feeder of the twin-screw extruder is stopped until all the resin in the twin-screw extruder is discharged, and dividing the volume by the free space volume in the twin-screw extruder.

[0034] It is preferable to replace the atmosphere inside the cylinder with an inert gas such as nitrogen gas or argon gas, or to evacuate it. For example, it is preferable to replace the air by supplying an inert gas such as nitrogen gas or argon gas from the raw material inlet (hopper, etc.). If the atmosphere is not replaced, the resin may become discolored (yellowing) due to oxidative degradation. When yellowing due to oxidative degradation occurs, the IR spectrum of the polymer alloy is observed, and the color of the resin may become yellow at 1700 cm ―1 In the polymer alloy according to this embodiment, a peak due to polycarbonate (1770 cm -1 ) and the peak due to polyester-based TPE (1740 cm -1) and is observed as a shoulder on the lower frequency side than these. The polymer alloy according to the present embodiment does not have such yellowing (1700 cm in the IR spectrum). ―1 (There should be no peaks in the vicinity)

[0035] The kneading zone is divided into two or more locations. A twin-screw extruder with a vent is used, with kneading zones located before and after the vent. Polycarbonate is hygroscopic, so if a vent is not installed, moisture can cause bubbles to form, impairing the transparency of the polymer alloy. Additionally, bubbles can cause interfacial stress, reducing the elongation at break.

[0036] [Wires, etc.] The polymer alloy according to this embodiment may be processed into a wire shape. The wire containing the polymer alloy according to this embodiment may have an aspect ratio (wire length / diameter) of 10 or more, for example.

[0037] The wire containing the polymer alloy according to this embodiment is highly transparent and can be processed like a wire by bending, twisting, and winding. The wire containing the polymer alloy according to this embodiment can be suitably used as an accessory, although it is not limited thereto.

[0038] The polymer alloy, the wire containing the polymer alloy, and the accessory containing the wire according to one embodiment of the present invention have been described above. According to this embodiment, a polymer alloy having high transparency, which can be plastically processed at room temperature and which is resistant to whitening even when repeatedly bent can be obtained. [Example]

[0039] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples.

[0040] Polymer alloys of polycarbonate and polyester-based TPE were produced under the conditions shown in Table 1. In Table 1, a "-" in the glass transition temperature column indicates that the glass transition temperature could not be observed.

[0041] [Table 1]

[0042] As the polycarbonate, Panlite (registered trademark) L1225Y, a polycarbonate manufactured by Teijin Limited, was used.

[0043] As the polyester-based TPE, Hytrel (registered trademark) 5557, a polyester-polyether type thermoplastic elastomer manufactured by Toray Celanese Co., Ltd., was used.

[0044] A twin-screw extruder with a 25 mm cylinder diameter was used to mix the materials under the conditions shown in Table 1. The cylinder temperature immediately after the inlet of the twin-screw extruder was set to 200°C. Polymer alloys with "A" in the "Screw Configuration" column of Table 1 were mixed using the screw configuration shown in Figure 1, while polymer alloys with "B" in the "Screw Configuration" column were mixed using the screw configuration shown in Figure 2. The kneading zone for the screw configuration shown in Figure 1 had an L / D ratio of 12.3, while the kneading zone for the screw configuration shown in Figure 2 had an L / D ratio of 3.5. The "number / number" in the flight name column refers to the "screw lead length / total length." The flight length is the axial length of each component divided by the cylinder diameter. "45°" and "60°" refer to the installation angles of the screw kneading disks. Except for test number 10, nitrogen gas was supplied through the raw material inlet to replace the air.

[0045] The produced polymer alloy was cut into a 1.0 mm thick plate, and the total light transmittance was measured using a HazeMeter NDH2000 manufactured by Nippon Denshoku Industries Co., Ltd. in accordance with JIS K 7105. Light C was used as the light source. A total light transmittance of 70% or more was evaluated as "Good", and a total light transmittance of less than 70% was evaluated as "Poor".

[0046] The yield stress and elongation at break were measured using a Technograph tension-compression testing machine manufactured by MinebeaMitsumi Inc. Specifically, the manufactured polymer alloy was molded into a string-shaped test piece with a diameter of 0.6 mm, and pulled at a temperature of 23°C ± 2°C at a tension rate of 17 mm / min. The chuck distance was 40 mm. The elongation and load at the time of yield and break of the test piece were recorded, and the yield stress and elongation at break were calculated. Elongation at break of 100% to 149% was evaluated as "△", elongation at break of 150% or more was evaluated as "〇", and elongation at break of less than 100% was evaluated as "X".

[0047] A string-shaped test piece with a diameter of 3 mm and a length of 100 mm was made from the produced polymer alloy, and it was bent 180 degrees and then unbent five times, and the presence or absence of whitening at the bent part was observed. It was confirmed that none of the test pieces made from the produced polymer alloy showed whitening.

[0048] As shown in Table 1, the polymer alloys of test numbers 2 to 5 had yield stresses of 30 to 55 MPa, values ​​smaller than those of the polymer of test number 6, which was a test example containing only polycarbonate. In other words, the polymer alloys of test numbers 2 to 5 had mechanical properties more suitable for plastic processing at room temperature than polycarbonate alone. These polymer alloys also had elongations at break of 150% or more. Furthermore, these polymer alloys had total light transmittances of 70% or more, maintaining the transparency of polycarbonate.

[0049] The polymer alloy of test number 10 had a lower yield stress than that of polycarbonate alone, and possessed mechanical properties suitable for plastic processing at room temperature. The polymer alloy of test number 10 also had an elongation at break of 150% or more. Although yellowing was observed in the polymer alloy of test number 10, the total light transmittance was 70% or more, and transparency was maintained. The yellowing observed in the polymer alloy of test number 10 is thought to be due to the oxidation of the resin because the atmosphere inside the twin-screw extruder was not replaced. Furthermore, when the IR spectrum of the polymer alloy of test number 10 was measured, a peak at 1700 cm ―1 A peak was observed near

[0050] The yield stress of the polymer alloy of test number 1 was not significantly different from that of the polymer of test number 6, which was a test example containing only polycarbonate. This is thought to be because the proportion of polycarbonate in the polymer alloy was too high.

[0051] The polymer of test number 7 (polyester-based TPE) had a total light transmittance of less than 70%.

[0052] The polymer alloys of test numbers 8 and 9 had glass transition temperatures at temperatures above 140°C. It is believed that the polycarbonate and polyester-based TPE were not sufficiently mixed in the polymer alloys of test numbers 8 and 9. As a result, the elongation at break of the polymer alloys of test numbers 8 and 9 was less than 100%. It is believed that the polycarbonate and polyester-based TPE were not sufficiently mixed because the kneading zone was too short.

[0053] The polymer alloy of test number 11 had a glass transition temperature of 140°C or higher. It is believed that the polycarbonate and polyester-based TPE were not sufficiently mixed in the polymer alloy of test number 11. As a result, the elongation at break of the polymer alloy of test number 11 was less than 100%. It is believed that the polycarbonate and polyester-based TPE were not sufficiently mixed because the screw rotation speed was too low.

[0054] The polymer alloys of test numbers 12 to 14 had elongations at break of 100% to 149%, which was within the acceptable range, but their processability was slightly inferior to that of the polymer alloys of test numbers 2 to 5 and test number 10. It is thought that the reason for this is that test numbers 12 and 14 were mixed in excess of what was necessary, and that test number 13 was heated more than necessary, causing the molecules to break.

[0055] By providing society with the polymer alloy produced by the present invention and products that use the polymer alloy of the present invention, it is possible to contribute to the achievement of Goal 9 (Build resilient infrastructure, promote inclusive and sustainable industrialization, innovate and promote innovation) out of the 17 Sustainable Development Goals (SDGs) established by the United Nations.

[0056] Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and various modifications are possible within the scope of the invention.

Claims

1. A polymer alloy of polycarbonate and polyester-based thermoplastic elastomer, a weight ratio of the polycarbonate to the polyester-based thermoplastic elastomer of 90:10 to 50:50; A polymer alloy that does not have a glass transition temperature at temperatures above 140°C.

2. 2. The polymer alloy according to claim 1, wherein the polyester-based thermoplastic elastomer is a block copolymer of polybutylene terephthalate and polyether.

3. The polymer alloy according to claim 1 or 2, wherein the glass transition temperature of the polymer alloy is lower by 5°C or more than the glass transition temperature of the polycarbonate alone contained in the polymer alloy.

4. 3. The polymer alloy according to claim 1, which has a total light transmittance of 70% or more as measured on a test piece having a thickness of 1.0 mm.

5. 3. The polymer alloy according to claim 1, having a yield stress of 30 to 55 MPa.

6. 3. The polymer alloy according to claim 1, wherein the elongation at break is 100% or more.

7. A wire comprising the polymer alloy of claim 1 or 2.

8. An accessory comprising the wire according to claim 7.

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