Asynchronous biaxial stretching polycarbonate glass material and preparation method thereof

Abstract

The invention belongs to the technical field of high polymer material preparation, and particularly relates to an asynchronous two-way stretching polycarbonate glass material and a preparation method thereof. The preparation method comprises the following steps: drying polycarbonate resin, mixing with a plasticizer, a color matching agent, an anti-aging agent, an antioxidant and an ultraviolet light absorber, and adding; carrying out blending granulation by using a double-screw extruder to obtain a blending modified raw material; adding the blended modified raw material into an injection molding machine, setting temperature and pressure, and performing injection molding to obtain a polycarbonate plate / sheet; the polycarbonate plate / sheet is subjected to asynchronous two-way stretching in a two-way stretching machine, the stretching temperature, the stretching rate and the stretching ratio are set, and the asynchronous two-way stretching polycarbonate glass material is obtained. Through the preparation method, the polycarbonate glass which is homogeneous and transparent and has excellent mechanical properties can be prepared.

Description

Technical Field

[0001] The present invention belongs to the technical field of polymer material preparation, and particularly relates to an asynchronous biaxially stretched polycarbonate glass material and a preparation method thereof. Background Art

[0002] Polymer glass generally refers to a class of polymer materials composed of long-chain molecules, having an amorphous structure, and exhibiting properties similar to those of glass. Due to its unique long-chain molecular characteristics (such as chain entanglement), polymer glass materials exhibit excellent toughness, high modulus, and excellent impact resistance different from those of small-molecule glass materials. Therefore, they are often used as key transparent structural materials and widely applied in fields such as construction, transportation, and new displays. In the field of high-end polymer glass, such as the windows of aerospace aircraft and automotive glass, foreign related technologies are in the leading position. In the field of automotive glass, foreign companies occupy most of the market. In 2022, the global market shares of Saint-Gobain of France, NSG Pilkington of Japan, and AGC Asahi Glass of Japan reached 15%, 17%, and 26% respectively. In the field of aviation glass, the global aviation glass supply basically belongs to three major foreign manufacturers (Saint-Gobain Group of France, GKN Company of the UK, and PPG Company of the US). Domestically, at present, the polymer glass industry mainly focuses on medium and low-end glass materials, and there is still a gap between the independently developed high-end products such as aerospace and automotive glass and foreign products. Therefore, it is urgent to develop advanced manufacturing technologies for polymer glass and develop independent production and application technologies for high-end polymer glass products.

[0003] The biaxial stretching processing technology is a processing method that regulates the polymer microstructure based on the biaxial stretching force field and temperature field, and has been proven to be able to significantly improve the strength, stiffness, and transparency of polymer materials. By reasonably controlling the temperature, stretching speed, and stretching ratio during the stretching process, biaxial stretching processing can make polymer materials have better mechanical properties and optical transparency, and thus has been widely applied in the production of high-performance films, packaging materials, optical lenses, and other fields.

[0004] At present, biaxially stretched polymethyl methacrylate (PMMA) aviation glass has been successfully applied. Biaxial stretching processing improves the toughness of PMMA, and great improvements have been made in preventing the generation of silver streaks and crack propagation. Therefore, it has gradually replaced non-oriented organic glass and has been widely adopted by countries around the world. Polycarbonate (PC) is a polymer glass material with excellent transparency, impact resistance, heat resistance, and dimensional stability. Compared with PMMA, it has higher strength, stiffness, and heat resistance. Using biaxial stretching processing is expected to be an effective processing method for high-performance PC high-grade window glass.

[0005] The biaxial stretching processing method can be divided into synchronous biaxial stretching processing and asynchronous biaxial stretching processing according to different polymer deformation modes. Synchronous biaxial stretching processing means stretching the polymer simultaneously in the longitudinal direction and the transverse direction, while asynchronous biaxial stretching processing is stretching in two directions successively. Different stretching modes will significantly affect the structure and properties of the material. Compared with synchronous biaxial stretching processing, asynchronous biaxial stretching processing has a preferred orientation direction and a higher efficiency of generating an oriented structure. Therefore, using the asynchronous biaxial stretching processing technology to process PC is expected to prepare PC glass materials with more excellent comprehensive properties. Therefore, asynchronous biaxial stretching of PC glass has good application prospects in automotive industry, rail transit, and aerospace aircraft window glass materials.

[0006] There are some patents on the biaxial stretching of polymer materials at present. For example, the patent with the publication number of CN1564951 discloses a "polycarbonate-based oriented film", which uses uniaxial and biaxial stretching processing methods to prepare aromatic polycarbonate films, and its application scenario is mainly the optical film of display devices. Another example is the patent with the publication number of CN116277907A, which discloses a "biaxially stretched polycarbonate glass material", and the processing method used is synchronous biaxial stretching, and there is a problem of low efficiency in generating an oriented structure in its processing method. Another example is the patent with the publication number of CN113412184A, which discloses a "biaxially stretched polyester film", and the polyester raw material used is characterized in that the polyester resin contains at least 1 kind selected from aluminum compounds and at least 1 kind selected from phosphorus compounds as polymerization catalysts. However, the currently disclosed invention patents do not involve the asynchronous biaxial stretching of bisphenol A polycarbonate.

[0007] In terms of literature, there is currently only one paper reporting the biaxial stretching of polycarbonate (Preparation and Properties of Biaxially Stretched Polycarbonate Films, Synthetic Resins and Plastics, 2015, 32(2): 39-42). This report studied the biaxial stretching behavior and properties of polycarbonate films with two melt flow rates (MFR of 6 and 20 g / 10 min (300 °C, 1.2 kg)). It was found that at a draw ratio of 2.5×2.5, the tensile modulus of the film increased compared to the unstretched film, but at a larger draw ratio (3.0×3.0), the tensile modulus decreased significantly. In addition, the tensile strength of the stretched film did not increase but decreased significantly: the tensile strengths of the two films decreased from 66.00 MPa to 60.57 - 65.19 MPa and from 65.00 MPa to 54.54 - 62.79 MPa respectively. Moreover, the ductility of the film also deteriorated sharply: the elongation at break of the two films decreased from 120.00% to 13.30% - 24.54% and from 120.00% to 22.30% - 44.76% respectively. Generally speaking, the comprehensive properties of the biaxially stretched polycarbonate films reported in this literature are significantly worse than those of the unstretched polycarbonate films. Summary of the Invention

[0008] In view of the deficiencies and defects of the prior art, the present invention provides a method for preparing an asynchronous biaxially stretched polycarbonate glass material, comprising the following steps:

[0009] S1: Dry the polycarbonate resin, and mix and add a plasticizer, a color matching agent, an anti-aging agent, an antioxidant, and an ultraviolet absorber; use a twin-screw extruder for melt blending and granulation to obtain a blend-modified raw material;

[0010] S2: Add the blend-modified raw material obtained in S1 into an injection molding machine, set the temperature, injection pressure, holding pressure, and mold temperature, and perform injection molding to obtain a polycarbonate material;

[0011] S3: Perform asynchronous biaxial stretching on the polycarbonate material obtained in S2 in a biaxial stretching machine, set the stretching temperature, stretching rate, and draw ratio to obtain an asynchronous biaxially stretched polycarbonate glass material.

[0012] Further, the polycarbonate resin in S1 is a bisphenol A type polycarbonate resin, the melt index of the polycarbonate resin is 5 - 30 g / min, the temperature for testing the melt index is 300 °C, and the test load is 2.16 kg.

[0013] Further, the mass fraction of the plasticizer described in S1 is 0.5 - 5.0 wt%, the mass fraction of the colorant is 0.5 - 2.0 wt%, the mass fraction of the anti-aging agent is 0.05 - 0.5 wt%, the mass fraction of the antioxidant is 0.1 - 1.0 wt%, and the mass fraction of the ultraviolet absorber is 0.05 - 0.5 wt%.

[0014] Further, the temperature described in S2 is set to 280 - 320 °C, the injection pressure is set to 50 - 140 MPa, the holding pressure is set to 50 - 140 MPa, and the mold temperature is set to 80 - 140 °C.

[0015] Further, the biaxial stretching method described in S2 is asynchronous biaxial stretching.

[0016] Further, the stretching rate described in S3 is 0.5 - 100 mm / s, the stretching ratio is 1.0 - 3.0, and the stretching temperature is 170 - 200 °C.

[0017] Further, the polycarbonate material described in S2 is any one of a sheet and a film.

[0018] An asynchronously biaxially stretched polycarbonate glass material, wherein the thickness of the polycarbonate glass material is 10 μm - 5 mm.

[0019] Beneficial Effects

[0020] Compared with the synchronous biaxial processing method of polycarbonate glass, a method for preparing polycarbonate glass by asynchronously biaxially stretching provided by the present invention can adopt multi-step control, which is easier in operation and structural control; and this method can solve the problems of non-uniform structure (skin-core structure) and local residual internal stress in injection-molded products; compared with the existing "casting - biaxial stretching" method, this method replaces the extrusion casting forming process with an injection molding process, and in addition to overcoming the defects of the extrusion casting process, it can also realize the preparation of a large number of polycarbonate glasses with uniform thickness.

[0021] Through a method for preparing polycarbonate glass by asynchronously biaxially stretching provided by the present invention, the obtained asynchronously biaxially stretched polycarbonate glass has a higher orientation structure generation efficiency, a higher degree of orientation, and thus a higher tensile strength compared with synchronous biaxial stretching due to having a preferred orientation direction, presenting the characteristics of high strength and high toughness.

[0022] The asynchronously biaxially stretched polycarbonate glass prepared by the method of the present invention has uniformly dispersed internal molecular chains, so it has better optical transparency and lower haze, and this asynchronously biaxially stretched polycarbonate glass can meet the application requirements in the fields of automotive, aerospace window glass, and aerospace masks. Description of the Drawings

[0023] To more clearly illustrate the technical solutions of the exemplary embodiments of the present invention, the following will briefly introduce the drawings required for the embodiments. It should be understood that the following drawings only show some embodiments of the present invention, and thus should not be regarded as limiting the scope. For those of ordinary skill in the art, without creative efforts, other related drawings can also be obtained based on these drawings. In the drawings:

[0024] Figure 1 It is a performance comparison chart of the unstretched and synchronous bi - directional and asynchronous bi - directional polycarbonate glasses of the embodiments of the present invention;

[0025] Figure 2 It is a mechanical property comparison chart of the polycarbonate glasses of the embodiments and comparative examples of the present invention;

[0026] Figure 3 It is an optical property comparison chart of the polycarbonate glasses of the embodiments and comparative examples of the present invention. Specific Embodiments

[0027] The following will combine Embodiments 1 - 6 of the present invention, Comparative Examples 1 - 2 and the attached Figures 1 to 3 , and clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of them. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope protected by the present invention.

[0028] Embodiment 1

[0029] S1. Place bisphenol A polycarbonate resin with a melt index of 10 g / 10 min (300 °C, 2.16 kg) in a dryer at 120 °C for dehumidifying and drying for 12 h. Subsequently, add it to a twin - screw extruder together with a plasticizer, a colorant, an anti - aging agent, an antioxidant, and an ultraviolet absorber in proportion (the percentage content of each component is shown in Table 1). Set the temperature range from the feeding port to the die to be 150 - 280 °C, the screw speed to be 60 r / min, and obtain a polycarbonate blend modified raw material through co - blending and pelletizing;

[0030] S2. Add the polycarbonate blend modified raw material into an injection molding machine. Set the temperatures of the injection molding machine from the hopper to the mold opening to be 280 °C, 300 °C, 320 °C, 300 °C, and 280 °C in sequence. Set the injection pressure to be 140 MPa, the holding pressure to be 120 MPa, and the mold temperature to be 120 °C. Through heating, the rotation of the single screw in the injection molding machine, and the injection system of the injection molding machine, melt, convey, and injection - mold the mixed raw material to obtain a polycarbonate sheet or plate with a thickness of 1000 μm, a length of 100 mm, and a width of 100 mm;

[0031] S3: Place the polycarbonate sheet or plate into a biaxial stretching machine for asynchronous biaxial stretching (the stretching ratio in asynchronous biaxial stretching is 1.5×1.5), set the first stretching ratio to 1.5, the stretching rate to 10 mm / s, and the stretching temperature to 190 °C, the second stretching ratio to 1.5, the stretching rate to 10 mm / s, and the stretching temperature to 190 °C, to obtain asynchronously biaxially stretched polycarbonate glass.

[0032] Record the asynchronously biaxially stretched polycarbonate glass obtained in Example 1 as PC~DR1.5.

[0033] Table 1 Composition components and molding process parameters of the polycarbonate blend modifier in Example 1

[0034]

[0035] Example 2

[0036] S1: The same as in Example 1;

[0037] S2: The same as in Example 1;

[0038] S3: The same as in Example 1, except that the stretching ratio in asynchronous biaxial stretching is 2.0×2.0.

[0039] Record the biaxially stretched polycarbonate glass obtained in Example 2 as PC~DR2.0~RATE10.

[0040] Example 3

[0041] S1: The same as in Example 1;

[0042] S2: The same as in Example 1;

[0043] S3: The same as in Example 1, except that the stretching ratio in asynchronous biaxial stretching is 2.5×2.5.

[0044] Record the biaxially stretched polycarbonate glass obtained in Example 3 as PC~DR2.5~RATE10.

[0045] Example 4

[0046] S1: The same as in Example 1;

[0047] S2: The same as in Example 1;

[0048] S3: The same as in Example 1, except that the stretching ratio in asynchronous biaxial stretching is 3.0×3.0.

[0049] Record the biaxially stretched polycarbonate glass obtained in Example 4 as PC~DR3.0~RATE10.

[0050] Example 5

[0051] S1: The same as in Example 1;

[0052] S2: The same as in Example 1;

[0053] S3: The same as in Example 1, except that the draw ratio in asynchronous biaxial stretching is 2.5×2.5 and the draw rate is 5 mm / s.

[0054] The biaxially stretched polycarbonate glass obtained in Example 5 is denoted as PC~DR2.5~RATE5.

[0055] Example 6

[0056] S1: The same as in Example 1;

[0057] S2: The same as in Example 1;

[0058] S3: The same as in Example 1, except that the draw ratio in asynchronous biaxial stretching is 2.5×2.5 and the draw rate is 20 mm / s.

[0059] The biaxially stretched polycarbonate glass obtained in Example 6 is denoted as PC~DR2.5~RATE20.

[0060] Control Example 1

[0061] S1: The same as in Example 1;

[0062] S2: The same as in Example 1;

[0063] S3: The same as in Example 1, except that the draw ratio in asynchronous biaxial stretching is 1.0×1.0 (i.e., not biaxially stretched).

[0064] The biaxially stretched polycarbonate glass obtained in Control Example 1 is denoted as PC~DR1.0.

[0065] Control Example 2

[0066] S1: The same as in Example 1;

[0067] S2: The same as in Example 1;

[0068] S3: The same as in Example 1, except that it is synchronous biaxial stretching, the draw ratio is 2.5×2.5, and the draw rate is 10 mm / s.

[0069] The biaxially stretched polycarbonate glass obtained in Control Example 2 is denoted as TBPC~DR2.5~RATE10.

[0070] The naming and stretching processing variables of Examples 1 to 6 and Comparative Examples 1 to 2 are specifically shown in Table 2.

[0071] Table 2 Naming and stretching variables of biaxially stretched polycarbonate glass

[0072]

[0073] Through Examples 1 to 6 and Comparative Examples 1 to 2, the present invention used an Instron electronic universal testing machine to test the tensile mechanical properties of the asynchronous biaxially stretched polycarbonate glass in the examples and the unstretched and synchronously biaxially stretched polycarbonate glass in the comparative examples. The yield strength, Young's modulus, ultimate tensile strength, elongation at break, and tensile toughness of the measured samples were summarized in Table 3.

[0074] Table 3 Test results of mechanical properties of Examples 1 to 6 and Comparative Examples 1 to 2

[0075]

[0076] Through testing, and in combination with Figure 2 It was found that the yield strength, tensile strength, Young's modulus, and elongation at break of the unstretched polycarbonate glass were 55.5 MPa, 64.1 MPa, 1169.6 MPa, and 200.6%, respectively. When the polycarbonate glass was biaxially stretched, at a draw ratio of 1.5 to 3.0, the yield strength, tensile strength, and Young's modulus of the polycarbonate glass were significantly improved and increased with the increase of the draw ratio. Among them, the yield strength gradually increased from 55.5 MPa (unstretched) to 92.4 MPa, the ultimate tensile strength gradually increased from 64.1 MPa to 119.7 MPa, the Young's modulus increased from 1169.6 MPa to 2205.0 MPa, and the tensile toughness increased from 80.4 MJ / m 3 gradually increased to 91.5 MJ / m 3 . The elongation at break decreased to a certain extent, gradually decreasing from 264.7% to 158.7%, but still had good toughness. With the further increase of the biaxial stretching ratio and stretching rate, the tensile toughness decreased to a certain extent. This is because too fast stretching rate and too large draw ratio will cause partial fracture of the PC molecular chain, resulting in a certain decrease in its ductility. Compared with the synchronously biaxially stretched polycarbonate glass, the asynchronously biaxially stretched polycarbonate glass has higher tensile strength, elongation at break, and tensile toughness under the same processing conditions. Thus, it can be seen that the asynchronously biaxial stretching process is more conducive to improving the mechanical properties of polycarbonate glass.

[0077] In combination with Figure 3, the present invention also used an ultraviolet-visible spectrophotometer to test the optical properties of the asynchronous biaxially stretched polycarbonate glass in the examples and the polycarbonate glass in the control examples. Table 4 statistically presents the results of visible light transmittance, haze, and yellowness obtained from the tests. It can be seen that the unstretched polycarbonate glass has relatively good optical properties, with a light transmittance, haze, and yellowness index of 89.4%, 1.98%, and 0.59, respectively. While the polycarbonate glass after asynchronous biaxial stretching exhibits more excellent optical properties. Specifically, as the stretching ratio increases, the light transmittance gradually increases, and the haze gradually decreases, reaching the optimal optical properties at a stretching ratio of 3.0, namely the highest light transmittance (90.9%) and the lowest haze (0.82%). This is mainly because asynchronous biaxial stretching promotes the orientation of PC molecular chains along the X-Y direction, the entangled molecular chains are separated, and a PC product with a more uniform microstructure is obtained, reducing optical losses such as birefringence caused by local structural inhomogeneity inside. And the yellowness has a certain increase compared to the unstretched polycarbonate glass. This is because the PC product after asynchronous biaxial stretching has experienced a more complex stretching external field, and the product will age to a certain extent. Generally speaking, the yellowness index of the PC after asynchronous biaxial stretching remains below 0.81, still having excellent transparency performance.

[0078] Table 4 Optical property test results of Examples 1 to 6 and Control Examples 1 to 2

[0079]

[0080]

[0081] The injection molding - asynchronous biaxial stretching processing method provided by the present invention has obvious advantages compared with the existing extrusion casting - synchronous biaxial processing method and injection molding - biaxial stretching method.

[0082] The advantages are as follows: The use of the asynchronous biaxial stretching processing technology can better regulate the amorphous structure, is more conducive to improving the generation efficiency of the oriented structure, and can solve the problems of uneven structure (skin-core structure) and local residual internal stress in injection molded products. In addition, this method replaces the casting molding process with injection molding, and can mass-produce polycarbonate glass with uniform thickness, improving production efficiency and product consistency.

[0083] Due to the preferential orientation of molecular chains, the polycarbonate glass processed by asynchronous biaxial stretching has higher tensile strength and fracture toughness compared with the glass processed by synchronous biaxial stretching. Through experimental tests, the asynchronous biaxially stretched polycarbonate glass is superior to the unstretched material in terms of tensile strength, yield strength, Young's modulus, etc., and maintains good tensile toughness. In addition, its optical properties are also significantly improved, and optical indicators such as light transmittance and haze reach excellent levels.

[0084] The asynchronous biaxially stretched polycarbonate glass of the present invention has broad application prospects in multiple high-end fields. For example, automotive glass and aerospace windows can all benefit from the present invention. The high strength, high toughness and excellent optical properties of this material make it of extremely high market value in these fields.

[0085] In summary, an asynchronous biaxially stretched polycarbonate glass provided by the preparation method of the present invention has good rigidity, toughness and excellent optical transparency, and can meet the application requirements of automotive, rail transit and aerospace aircraft window glass. Moreover, the "asynchronous biaxial stretching" processing method of the polycarbonate glass proposed by the present invention has the advantages of fast speed, high efficiency, scalable production, saving industrial costs, protecting the environment, etc., and is of great significance for promoting the application of polycarbonate glass in important engineering fields.

Claims

1. A method for preparing an asynchronous biaxially stretched polycarbonate glass material, characterized in that, It includes the following steps: S1: Dry the polycarbonate resin, and add it after mixing with a plasticizer, a colorant, an anti-aging agent, an antioxidant, and an ultraviolet absorber; perform melt blending and pelletizing with a twin-screw extruder to obtain a blend-modified raw material; S2: Add the blend-modified raw material obtained in S1 into an injection molding machine, set the temperature, injection pressure, holding pressure, and mold temperature, and perform injection molding to obtain a polycarbonate material; S3: Perform asynchronous biaxial stretching on the polycarbonate material obtained in S2 in a biaxial stretching machine, set the stretching temperature, stretching rate, and stretching ratio to obtain an asynchronous biaxially stretched polycarbonate glass material.

2. The preparation method of an asynchronous biaxially stretched polycarbonate glass material according to claim 1, characterized in that, The polycarbonate resin described in S1 is a bisphenol A type polycarbonate resin, the melt index of the polycarbonate resin is 5 - 30 g / min, the temperature for testing the melt index is 300 °C, and the test load is 2.16 kg.

3. The preparation method of an asynchronous biaxially stretched polycarbonate glass material according to claim 1, characterized in that The mass fraction of the plasticizer described in S1 is 0.5 - 5.0 wt%, the mass fraction of the colorant is 0.5 - 2.0 wt%, the mass fraction of the anti-aging agent is 0.05 - 0.5 wt%, the mass fraction of the antioxidant is 0.1 - 1.0 wt%, and the mass fraction of the ultraviolet absorber is 0.05 - 0.5 wt%.

4. The preparation method of an asynchronous biaxially stretched polycarbonate glass material according to claim 1, characterized in that, The temperature described in S2 is set to 280 - 320 °C, the injection pressure is set to 50 - 140 MPa, the holding pressure is set to 50 - 140 MPa, and the mold temperature is set to 80 - 140 °C.

5. The preparation method of an asynchronous biaxially stretched polycarbonate glass material according to claim 1, wherein, The biaxial stretching method described in S2 is asynchronous biaxial stretching.

6. The preparation method of an asynchronous biaxially stretched polycarbonate glass material according to claim 1, characterized in that, The stretching rate described in S3 is 0.5 - 100 mm / s, the stretching ratio is 1.0 - 3.0, and the stretching temperature is 170 - 200 °C.

7. The preparation method of an asynchronous biaxially stretched polycarbonate glass material according to claim 1, characterized in that, The polycarbonate material described in S2 is any one of a sheet and a film.

8. An asynchronous biaxially stretched polycarbonate glass material obtained by the preparation method according to any one of claims 1 to 7, characterized in that, The thickness of the polycarbonate glass material is 10 μm - 5 mm.

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