Pmma film and method for producing the same

Abstract

The present invention relates to a PMMA film comprising a polymerization reaction product of: (a) a methyl methacrylate monomer; (b) a second monomer; (c) an initiator; (d) a chain transfer agent; (e) a crosslinking agent. The second monomer comprises at least one of butyl methacrylate, butyl acrylate, acrylic acid, methacrylic acid. The crosslinking agent comprises a di(meth)acrylate crosslinking agent. The present invention also relates to a method of making the aforementioned PMMA film.

Description

Technical Field

[0001] This invention relates to the field of polymethyl methacrylate (PMMA) preparation technology, and in particular to a PMMA film and a method for preparing the PMMA film. Background Technology

[0002] This section provides background information relevant to this application, which does not necessarily constitute prior art.

[0003] Polymethyl methacrylate (PMMA) is an amorphous polymer material, commonly known as plexiglass. It possesses excellent properties such as high light transmittance, ease of processing and molding, good weather resistance, and good electrical insulation, making it widely used in agriculture, aerospace, construction, and optical instruments. However, existing PMMA materials suffer from the following technical problems:

[0004] 1. PMMA is produced by free radical polymerization of methyl methacrylate monomer (MMA). Its molecular chain contains thermally unstable structures, making it prone to thermal degradation and resulting in a low glass transition temperature (T0). g The temperature is approximately 100℃, and thermal degradation typically begins at 150℃.

[0005] 2. PMMA has poor mechanical strength, resulting in low tensile strength, which limits its application range.

[0006] To improve the heat resistance and mechanical strength of PMMA resin, existing technical solutions include copolymerization modification, which adjusts the molecular chain structure, aggregate structure, or texture structure to improve certain specific properties of the polymer. PMMA is a typical amorphous polymer material. By introducing rigid side chains with large-volume groups onto the main chain, the internal rotation of the macromolecular main chain can be suppressed, reducing chain segment mobility and increasing chain segment rigidity, thereby improving heat resistance and mechanical strength. Adding a main-valence crosslinking agent allows direct chain formation between molecular chains, changing the polymer from a linear structure to a three-dimensional structure, significantly reducing the mobility of molecular chain segments, which can also significantly improve the heat resistance and mechanical strength of PMMA. However, existing technical solutions have the following technical problems:

[0007] To improve T g The value involves copolymerizing MMA with rigid or bulky monomers (such as maleic anhydride, cyclohexyl methacrylate, or methacrylamide), but unless a high content of rigid monomers is used, T... g The increase is not significant, but using a higher content of rigid monomers will reduce the transparency of PMMA.

[0008] Therefore, the synthesis and preparation of high T gAchieving high light transmittance in PMMA remains a significant challenge. Crosslinking of the polymer can improve its mechanical properties, and introducing crosslinkable groups into the backbone can enhance its thermal stability. This invention aims to provide a PMMA material with excellent overall performance, which has broad application prospects in the optical field. Summary of the Invention

[0009] To achieve the above objectives, the present invention adopts the following technical solution: The present invention provides a PMMA membrane, which comprises a polymerization reaction product of the following components:

[0010] (a) Methyl methacrylate monomer (MMA);

[0011] (b) Second monomer;

[0012] (c) Initiator;

[0013] (d) Chain transfer agents;

[0014] (e) Crosslinking agent.

[0015] Based on the total weight of components (a) and (b), the amount of MMA used is 70%-100%, for example 70%, 72%, 75%, 78%, 80%, 82%, 85%, 87%, 90%, 92%, 95%, 98%, or 100%, and the amount of the second monomer used is 0-30%, for example 2%, 5%, 8%, 10%, 13%, 15%, 18%, 20%, 22%, 25%, 28%, or 30%.

[0016] Based on the total weight of components (a) and (b), the amount of the initiator is 0.1%-1%, for example 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9% or 1%.

[0017] Based on the total weight of components (a) and (b), the amount of the chain transfer agent is 0.02%-1%, for example 0.02%, 0.03%, 0.04%, 0.05%, 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, or 1%.

[0018] Based on the total weight of components (a) and (b), the amount of the crosslinking agent is 1%-10%, for example 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5%, 5.5%, 6%, 6.5%, 7%, 7.5%, 8%, 8.5%, 9%, 9.5%, or 10%.

[0019] The second monomer includes at least one of butyl methacrylate (BMA), butyl acrylate (BA), acrylic acid (AA), and methacrylic acid (MAA).

[0020] The initiator includes at least one of azo initiators and organic peroxide initiators. Preferably, the initiator is 1,1-di-tert-butylperoxide-3,3,5-trimethylcyclohexane.

[0021] The chain transfer agent includes at least one of n-butanethiol, isobutanethiol, sec-butylthiol, tert-butylthiol, n-octanethiol, isooctanethiol, n-dodecylthiol, sec-dodecylthiol, and tert-dodecylthiol.

[0022] The crosslinking agent includes di(meth)acrylate crosslinking agents. Preferably, the crosslinking agent includes at least one of tetraethylene glycol diacrylate, tetraethylene glycol dimethacrylate (TTEGMA), polyethylene glycol dimethacrylate, bis(4-methacryloylthiophenyl) sulfide, N,N′-methylenebisacrylamide, and bisphenol A dimethacrylate.

[0023] The PMMA membrane provided by this invention has a cross-linked structure, and this PMMA membrane also has high T g It has high light transmittance and excellent mechanical strength.

[0024] On the other hand, the present invention also provides a method for preparing the above-mentioned PMMA film, comprising the following steps:

[0025] Step 1: Methyl methacrylate monomer (MMA), second monomer, initiator, and chain transfer agent are added to the reactor and mixed and reacted. Bulk polymerization is carried out until bubbles appear in the reaction liquid. Then the reaction is quenched to obtain liquid resin.

[0026] Step 2: Mix the liquid resin and crosslinking agent until uniform, degas, and then apply a coating to form a film. After curing, the PMMA film is obtained.

[0027] In step one, the bulk polymerization reaction is carried out at a temperature of 70-100°C, for example, 70°C, 75°C, 80°C, 85°C, 90°C, 95°C, or 100°C. The bulk polymerization reaction is conducted under a protective atmosphere, preferably nitrogen. The conversion rate of the bulk polymerization reaction reaches approximately 20%-30%.

[0028] In step one, the quenching specifically involves transferring the reactor to a low-temperature environment to cool the reaction, or more specifically, cooling it to room temperature.

[0029] In step two, the mixing includes ultrasonic mixing, and the ultrasonic mixing time is not less than 10 minutes, for example, 10 minutes, 15 minutes, 20 minutes, 25 minutes or 30 minutes.

[0030] In step two, the degassing time is not less than 20 minutes, for example, 20 minutes, 25 minutes, 30 minutes, 35 minutes, or 40 minutes. Preferably, the degassing is vacuum degassing.

[0031] In step two, the coating film thickness is 50-200μm, for example 50μm, 60μm, 70μm, 80μm, 90μm, 100μm, 110μm, 120μm, 130μm, 140μm, 150μm or 200μm.

[0032] In step two, the curing temperature is 40-100℃, for example, 40℃, 45℃, 50℃, 55℃, 60℃, 65℃, 70℃, 75℃, 80℃, 85℃, 90℃, 95℃ or 100℃.

[0033] Compared with the prior art, the present invention has the following beneficial effects:

[0034] 1. The PMMA film provided by this invention is a ternary copolymerized product with methyl methacrylate (MMA) as the main monomer, a second monomer introduced, and a crosslinking agent added. Due to the introduction of the second monomer into the side chain structure, the activation energy of chain segment movement increases, the rotation within the molecular chain is severely hindered, and the flexibility deteriorates. While ensuring the light transmittance of the PMMA film, the heat resistance of the PMMA film is improved. The addition of the crosslinking agent causes covalent bonds to form between polymer macromolecules, changing the linear structure to a three-dimensional structure, reducing the chain segment mobility, and greatly improving the heat resistance and mechanical strength of the PMMA film.

[0035] 2. The PMMA film preparation method provided by this invention employs a bulk polymerization method, which is solvent-free, environmentally friendly, and energy-efficient. It uses a stepwise polymerization method, controlling the low conversion rate in the pre-polymerization stage, and employing a low-temperature, slow polymerization method for the secondary polymerization, thus preventing explosive polymerization and ensuring the quality of the PMMA film. The PMMA film prepared by this invention has high heat resistance and strength, as well as good light transmittance, with a glass transition temperature up to T... g It can reach a temperature of not less than 125℃, a light transmittance of not less than 95%, and has excellent mechanical strength.

[0036] The following description is based on specific embodiments. Detailed Implementation

[0037] It should be understood that the specific embodiments described herein are for illustrative purposes only and are not intended to limit the scope of the invention.

[0038] [Examples 1-6]

[0039] Examples 1-6 all provide a PMMA membrane, and the specific component formulations are shown in Table 1.

[0040] The method for preparing the PMMA membrane provided in Example 1 includes the following steps:

[0041] Step 1: Add MMA, initiator and chain transfer agent to a three-necked flask and carry out bulk polymerization reaction under nitrogen atmosphere. The reaction temperature of bulk polymerization reaction is 90℃. React until bubbles appear in the reaction liquid. Then quickly transfer the three-necked flask to an ice bath to quench the reaction and obtain PMMA prepolymer (i.e. liquid resin).

[0042] Step 2: The obtained prepolymer solution and crosslinking agent are ultrasonically mixed until uniform, vacuum degassing is performed for 30 minutes, and then a film is laid by coating. The film is dried and cured at 40°C for 8 hours to obtain a PMMA film with a thickness of 200 μm and uniform and transparent texture.

[0043] The method for preparing the PMMA membrane provided in Example 2 includes the following steps:

[0044] Step 1: Add MMA, second monomer, initiator and chain transfer agent to a three-necked flask and carry out bulk polymerization reaction under nitrogen atmosphere. The reaction temperature of bulk polymerization reaction is 80℃. React until bubbles appear in the reaction liquid. Then quickly transfer the three-necked flask to an ice bath to quench the reaction and obtain PMMA prepolymer liquid (i.e. liquid resin).

[0045] Step 2: The obtained prepolymer solution and crosslinking agent are ultrasonically mixed until uniform, vacuum degassing is performed for 30 minutes, and then a film is laid by coating. The film is dried and cured at 70°C for 12 hours to obtain a PMMA film with a thickness of 100 μm and uniform and transparent texture.

[0046] The method for preparing the PMMA membrane provided in Example 3 includes the following steps:

[0047] Step 1: Add MMA, second monomer, initiator and chain transfer agent to a three-necked flask and carry out bulk polymerization reaction under nitrogen atmosphere. The reaction temperature of bulk polymerization reaction is 80℃. React until bubbles appear in the reaction liquid. Then quickly transfer the three-necked flask to an ice bath to quench the reaction and obtain PMMA prepolymer liquid (i.e. liquid resin).

[0048] Step 2: The obtained prepolymer solution and crosslinking agent are ultrasonically mixed until uniform, vacuum degassing is performed for 30 minutes, and then a film is laid by coating. The film is dried and cured at 70°C for 12 hours to obtain a PMMA film with a thickness of 100 μm and uniform and transparent texture.

[0049] The methods for preparing PMMA membranes provided in Examples 4-6 all include the following steps:

[0050] Step 1: Add MMA, second monomer, initiator and chain transfer agent to a three-necked flask and carry out bulk polymerization reaction under nitrogen atmosphere. The reaction temperature of bulk polymerization reaction is 70°C. React until bubbles appear in the reaction liquid. Then quickly transfer the three-necked flask to an ice bath to quench the reaction and obtain PMMA prepolymer (i.e. liquid resin).

[0051] Step 2: The obtained prepolymer solution and crosslinking agent are ultrasonically mixed until uniform, vacuum degassing is performed for 30 minutes, and then a film is laid by coating. The film is dried and cured at 70°C for 12 hours to obtain a PMMA film with a thickness of 160 μm and uniform and transparent texture.

[0052] Table 1

[0053]

[0054] [Comparative Examples 1-6]

[0055] Comparative Examples 1-6 each provide a PMMA membrane, and the preparation methods of the PMMA membranes provided in Comparative Examples 1-6 are the same as those of the PMMA membrane provided in Example 6.

[0056] The PMMA membrane provided in Comparative Example 1 differs from the PMMA membrane provided in Example 1 only in that no crosslinking agent is used in the preparation of the PMMA membrane in Comparative Example 1.

[0057] The PMMA membrane provided in Comparative Example 2 differs from the PMMA membrane provided in Example 1 only in that the crosslinking agent used to prepare the PMMA membrane in Comparative Example 2 is 2,2-bis[4-(acryloyloxy-propoxy)phenyl]propane.

[0058] The PMMA membrane provided in Comparative Example 3 differs from the PMMA membrane provided in Example 1 only in that the crosslinking agent used to prepare the PMMA membrane in Comparative Example 3 is 1,2-divinylbenzene.

[0059] The PMMA membrane provided in Comparative Example 4 differs from the PMMA membrane provided in Example 1 only in that the crosslinking agent used to prepare the PMMA membrane in Comparative Example 4 is pentaerythritol propoxy acrylate.

[0060] The PMMA membrane provided in Comparative Example 5 differs from the PMMA membrane provided in Example 1 only in that the crosslinking agent used to prepare the PMMA membrane in Comparative Example 5 is triallyl cyanurate (TAC).

[0061] The PMMA membrane provided in Comparative Example 6 differs from the PMMA membrane provided in Example 1 only in that the crosslinking agent used to prepare the PMMA membrane in Comparative Example 6 is dioctyl phthalate (DOP).

[0062] [Comparison Test]

[0063] The PMMA membranes provided in Examples 1-6 and Comparative Examples 1-6 were subjected to the following tests:

[0064] (1) Elongation at break, tensile strength and tensile modulus: tested in accordance with GB / T1040.2-2022;

[0065] (2) Refractive index: Tested in accordance with GB / T 39691-2020;

[0066] (3) Light transmittance and haze: Tested in accordance with GB / T2410-2008;

[0067] (4) Glass transition temperature: The static glass transition temperature (Tg) is determined by dynamic scanning calorimetry according to DIN 53765. g The values ​​are based on the glass transition temperature T in DIN 53765:1994-03. g ;

[0068] (5) Aging resistance test: The PMMA film was cut into 0.5m×0.8m samples, and 20 samples were placed in a xenon lamp aging test chamber. The xenon lamp was used as the light source to test the aging resistance of the samples. In one test cycle, 5 hours of light irradiation (light radiation intensity of 2kW / m²) were performed sequentially. 2 The sample was subjected to 5 hours of condensation (at an ambient temperature of 60℃) and 5 hours of condensation (at an ambient temperature of 25℃) for 100 cycles, for a total of 1000 hours. After the test, the outer surface of the sample was visually inspected. If no cracks or deformations appeared on the outer surface of the sample, it was deemed qualified (marked as "○" in Table 2). If cracks and / or deformations appeared on the outer surface of the sample, it was deemed unqualified (marked as "×" in Table 2).

[0069] The test results are shown in Table 2.

[0070] Table 2

[0071]

[0072] As can be seen from Table 2 above, the PMMA films provided in Examples 1-6, by introducing specific second monomers and crosslinking agents for ternary crosslinking copolymerization, can improve the heat resistance, tensile strength and aging resistance of polymethyl methacrylate monomer resin, while maintaining excellent light transmittance.

[0073] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0074] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.

Claims

1. A PMMA membrane, characterized in that, The PMMA membrane comprises the polymerization product of the following components: (a) Methyl methacrylate monomer; (b) Second monomer; (c) Initiator; (d) Chain transfer agents; (e) Crosslinking agent; Based on the total weight of components (a) and (b), the amount of the methyl methacrylate monomer is 70%-100%, and the amount of the second monomer is 0-30%. Based on the total weight of components (a) and (b), the amount of the initiator is 0.1%-1%, the amount of the chain transfer agent is 0.02%-1%, and the amount of the crosslinking agent is 1%-10%. The second monomer includes at least one of butyl methacrylate, butyl acrylate, acrylic acid, and methacrylic acid; The crosslinking agent includes di(meth)acrylate crosslinking agents.

2. The PMMA membrane according to claim 1, characterized in that, The crosslinking agent includes at least one of tetraethylene glycol diacrylate, tetraethylene glycol dimethacrylate, polyethylene glycol dimethacrylate, bis(4-methacryloylthiophenyl) sulfide, N,N′-methylenebisacrylamide, and bisphenol A dimethacrylate.

3. The PMMA membrane according to claim 1, characterized in that, The initiator includes at least one of azo initiators and organic peroxide initiators.

4. The PMMA membrane according to claim 3, characterized in that, The initiator is 1,1-di-tert-butylperoxide-3,3,5-trimethylcyclohexane.

5. The PMMA membrane according to claim 1, characterized in that, The chain transfer agent includes at least one of n-butanethiol, isobutanethiol, sec-butylthiol, tert-butylthiol, n-octanethiol, isooctanethiol, n-dodecylthiol, sec-dodecylthiol, and tert-dodecylthiol.

6. A method for preparing the PMMA membrane according to any one of claims 1-5, characterized in that, Includes the following steps: Step 1: Methyl methacrylate monomer, second monomer, initiator, and chain transfer agent are added to the reactor and mixed to react. Bulk polymerization is carried out until bubbles appear in the reaction liquid. Then the reaction is quenched to obtain liquid resin. Step 2: Mix the liquid resin and crosslinking agent until uniform, degas, and then apply a coating to form a film. After curing, the PMMA film is obtained.

7. The method according to claim 6, characterized in that, The bulk polymerization reaction is carried out at a temperature of 70-100°C under a protective atmosphere; the quenching is performed by transferring the reactor to a low-temperature environment to cool the reaction.

8. The method according to claim 6, characterized in that, The mixing includes ultrasonic mixing, and the ultrasonic mixing time is not less than 10 minutes.

9. The method according to claim 6, characterized in that, The degassing time is not less than 20 minutes, and the degassing is vacuum degassing.

10. The method according to claim 6, characterized in that, The coating thickness is 50-200 μm, and the curing temperature is 40-100℃.

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