Reinforced and toughened PMMA material and preparation method thereof

Abstract

The present application relates to a reinforced and toughened PMMA material and a preparation method thereof, the preparation method comprising the following steps: forming a liquid phase system, the liquid phase system comprising a polymethyl methacrylate prepolymer, methyl methacrylate and an initiator; sequentially adding a polyol polymer and a short-range connection unit to the liquid phase system; casting and polymerizing, and allowing the polyol polymer to interact with the short-range connection unit to obtain a reinforced and toughened PMMA material. The technical solution of the present application, through the interaction between the polyol polymer and the short-range connection unit, the short-range connection unit can form a connection structure between the polyol polymers that is interspersed between the polymethyl methacrylate polymer chains, and the polyol polymer and the short-range connection unit form a closed-loop structure that surrounds the polymethyl methacrylate polymer chain, thereby effectively improving the toughness and strength of the PMMA material.

Description

Technical Field

[0001] The present application relates to the technical field of polymer materials, and in particular to a reinforced and toughened PMMA material and a preparation method thereof. Background Art

[0002] As a new type of polymer material with both strength and toughness, high-strength and toughness polymers have received extensive attention from academia and industry. In many key areas, such as rail transportation, aerospace, electronic communications, and medical devices, the research progress of this type of material largely determines the development level of related cutting-edge technologies and people's living standards. In particular, transparent materials represented by PMMA (Polymethyl methacrylate) have outstanding application advantages in the above fields, such as easy molding, good functional expansion, and high optical transmission. However, the defects of low strength and insufficient toughness have caused a great degree of limitation on their large-scale promotion. Relevant research data show that there has always been a strong demand for PMMA transparent materials with enhanced mechanical properties in the field of engineering applications, among which tensile strength and toughness expression characterized by impact resistance are two main parameters that need to be paid attention to.

[0003] However, when trying to improve the tensile strength, the existing technology often uses the method of adding diene or polyene crosslinking agents and participating in MMA (Methyl methacrylate) copolymerization. The increase in the degree of crosslinking is accompanied by an increase in the brittleness of the molded material, which inevitably leads to a decrease in impact resistance. Therefore, the current difficulty lies in how to break the balance limit between the strength and toughness of PMMA materials and achieve consistency improvement between the two. Summary of the invention

[0004] In response to the above technical problems, the present application provides a reinforced and toughened PMMA material and a preparation method thereof, which can effectively improve the toughness and strength of the PMMA material.

[0005] In order to solve the above technical problems, the present application provides a method for preparing a reinforced and toughened PMMA material, comprising the following steps:

[0006] S1. forming a liquid phase system, the liquid phase system comprising a polymethyl methacrylate prepolymer, methyl methacrylate and an initiator;

[0007] S2. sequentially adding a polyol polymer and a short-range connection unit to the liquid phase system;

[0008] S3. pouring, polymerizing, and allowing the polyol polymer to interact with the short-range connection unit to obtain a reinforced and toughened PMMA material;

[0009] Wherein, the polyol polymer is selected from polyether polyol or polyester polyol, wherein the molecular structure of the polyether polyol is molecular structure (i); and the molecular structure of the polyester polyol is molecular structure (ii):

[0010]

[0011] R 1 C α H 2α O x (α is an integer ≥1, x is an integer ≥0 and x<α), n1 is an integer ≥1; R 2 C β H 2β O y (β is an integer ≥1, y is an integer ≥0 and y<β), R 3 C γ H 2γ O z (γ is an integer ≥1, z is an integer ≥0 and z<γ), n2 is an integer ≥1;

[0012] The molecular structure of the short-range connection unit is at least one of the molecular structures (i') to (vi'):

[0013]

[0014] Among them, X 3 It is a straight chain structure.

[0015] Optionally, when the molecular structure of the short-range connection unit is molecular structure (iv′), (v′) or (vi′), the mass proportion of the polymethyl methacrylate prepolymer is 2 to 10%, the mass proportion of the methyl methacrylate is ≥50%, the mass proportion of the initiator is ≤0.5%, the mass proportion of the polyol polymer is 2 to 20%, and the mass proportion of the short-range connection unit is 1 to 10%.

[0016] Optionally, when the molecular structure of the short-range connection unit is the molecular structure (i′), (ii′) or (iii′), a catalyst for catalyzing the reaction between the polyol polymer and the short-range connection unit is further added in the step S2.

[0017] Optionally, the mass proportion of the polymethyl methacrylate prepolymer is 2-10%, the mass proportion of the methyl methacrylate is ≥50%, the mass proportion of the initiator is ≤0.5%, the mass proportion of the polyol polymer is 2-20%, the mass proportion of the short-range connection unit is 1-10%, and the mass proportion of the catalyst is ≤0.5%.

[0018] Optionally, the liquid phase system further comprises a functional monomer, which is an unsaturated monomer having water absorption after polymerization; the functional monomer is used to form a copolymer chain with the methyl methacrylate.

[0019] Optionally, the functional monomer is a weakly alkaline unsaturated monomer, and the catalyst is an acidic compound.

[0020] Optionally, the mass proportion of the polymethyl methacrylate prepolymer is 2-10%, the mass proportion of the methyl methacrylate is ≥50%, the mass proportion of the functional monomer is ≤9%, the mass proportion of the initiator is ≤0.5%, the mass proportion of the polyol polymer is 2-20%, the mass proportion of the short-range connection unit is 1-10%, and the mass proportion of the catalyst is ≤0.5%.

[0021] Optionally, the S2 step includes:

[0022] adding a polyol polymer;

[0023] After stirring to mix, add the short-range connection unit.

[0024] Optionally, the S3 step includes:

[0025] When the initiator is a thermosensitive initiator, firstly place in a water bath or a forced air bath at 45-75°C for 2-12 hours, and then place in a forced air bath at 105-135°C for 1-8 hours;

[0026] When the initiator is a photosensitive initiator, the ultraviolet light of 220-380 nm is irradiated at room temperature for 1-2 hours.

[0027] The present application also provides a reinforced and toughened PMMA material, which is prepared by the method for preparing the reinforced and toughened PMMA material as described in any of the above items.

[0028] The reinforced and toughened PMMA material and preparation method of the present application include the following steps: forming a liquid phase system, the liquid phase system includes polymethyl methacrylate prepolymer, methyl methacrylate and initiator; adding polyol polymer and short-range connection unit to the liquid phase system in sequence; casting, polymerization, and making the polyol polymer interact with the short-range connection unit to obtain a reinforced and toughened PMMA material. The technical solution of the present application, through the interaction between the polyol polymer and the short-range connection unit, the short-range connection unit can form a connection structure between the polyol polymers that is interspersed between the polymethyl methacrylate polymer chains, and the polyol polymer and the short-range connection unit form a closed-loop structure surrounding the polymethyl methacrylate polymer chain, which effectively improves the toughness and strength of the PMMA material. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1is a schematic flow chart of a method for preparing a reinforced and toughened PMMA material according to an embodiment;

[0030] Figure 2 is a schematic diagram of the molecular structure of a polyol polymer according to an embodiment;

[0031] Figure 3 is a schematic diagram of a molecular structure of a short-range connection unit according to an embodiment;

[0032] Figure 4 is a schematic diagram showing the principle of interaction between a polyol polymer and a short-range connection unit according to an embodiment;

[0033] Figure 5 is a schematic diagram of the microstructure of a reinforced and toughened PMMA material according to an embodiment;

[0034] Figure 6 is a comparison diagram of light transmittance characterization results according to an embodiment. DETAILED DESCRIPTION

[0035] The following is an explanation of the implementation of the present application by means of specific embodiments. People familiar with the art can easily understand other advantages and effects of the present application from the contents disclosed in this specification.

[0036] In the following description, reference is made to the accompanying drawings, which describe several embodiments of the present application. It should be understood that other embodiments may be used and that mechanical, structural, electrical, and operational changes may be made without departing from the spirit and scope of the present application. The following detailed description should not be considered limiting, and the terms used herein are only for the purpose of describing specific embodiments and are not intended to limit the present application.

[0037] Although the terms first, second, etc. are used herein to describe various elements in some instances, these elements should not be limited by these terms. These terms are only used to distinguish one element from another element.

[0038] Furthermore, as used in this article, the singular forms "one", "an" and "the" are intended to include plural forms as well, unless there is an indication to the contrary in the context. It should be further understood that the terms "comprise", "include" indicate the presence of the described features, steps, operations, elements, components, projects, kinds, and / or groups, but do not exclude the presence, occurrence or addition of one or more other features, steps, operations, elements, components, projects, kinds, and / or groups. The terms "or" and "and / or" used herein are interpreted as inclusive, or mean any one or any combination. Therefore, "A, B or C" or "A, B and / or C" means "any of the following: A; B; C; A and B; A and C; B and C; A, B and C". Exceptions to this definition will only occur when the combination of elements, functions, steps or operations is inherently mutually exclusive in some way.

[0039] Figure 1 FIG. 1 is a schematic flow chart of a method for preparing a reinforced and toughened PMMA material according to an embodiment. Figure 1 As shown, a method for preparing a reinforced and toughened PMMA material of the present application comprises the following steps:

[0040] S1. forming a liquid phase system, wherein the liquid phase system comprises polymethyl methacrylate prepolymer, methyl methacrylate and an initiator.

[0041] The initiator is a compound that can decompose into free radicals. The minimum temperature when it decomposes to produce free radicals is 45-100°C, and the half-life is 10 0 ~10 1 h, can be a thermal initiator, can also be a photosensitive initiator, or a combination of the two. The initiator includes at least one of BPO, AIBN, ABVN, methyl vinyl ketone, benzoin, xylene ketone, fluorescein, and eosin, that is, a single initiator or a combination of initiators can be selected.

[0042] The polymethyl methacrylate prepolymer is formed by a polymer chain. The proportion of the polymethyl methacrylate prepolymer in the liquid phase system can be obtained by controlling the polymerization reaction process of methyl methacrylate and stopping the polymerization process of methyl methacrylate in stages. For example, the stop point is judged by using the 4-cup viscosity index to obtain the polymethyl methacrylate prepolymer with the corresponding mass proportion. In addition, it can also be obtained by dissolving PMMA resin masterbatch in methyl methacrylate to prepare a solution with a suitable viscosity (in this case, the polymethyl methacrylate prepolymer is directly provided by the PMMA resin masterbatch).

[0043] After the polymer solution is formed by any of the above two methods and cooled to room temperature, the initiator is added. When calculating the amount of initiator added, the residual initiator content in the original bulk polymerization or resin masterbatch is not taken into account.

[0044] S2. sequentially adding a polyol polymer and a short-range connection unit to the liquid phase system;

[0045] The polyol polymer is miscible with methyl methacrylate, and the polyol polymer is selected from polyether polyol or polyester polyol, wherein the molecular structure of the polyether polyol is Figure 2 The molecular structure (i) shown; the molecular structure of polyester polyol is Figure 2 The molecular structure shown in (ii). 1 C α H 2α O x (α is an integer ≥1, x is an integer ≥0 and x<α), n1 is an integer ≥1; R 2 C β H 2β O y (β is an integer ≥1, y is an integer ≥0 and y<β), R 3 C γ H 2γ O z (γ is an integer ≥1, z is an integer ≥0 and z<γ), n2 is an integer ≥1.

[0046] The short-range linking unit is miscible with methyl methacrylate and includes a first linear compound that can form a chemical bond with the hydroxyl site of the polyol polymer, selected from Figure 3 One or more of the molecular structures (i'), (ii'), (iii'), and / or a second linear compound capable of generating hydrogen bonds with the hydroxyl sites of the polyol polymer, selected from Figure 3 One or more of the molecular structures (iv'), (v'), (vi'). 3 is a straight chain structure, specifically a saturated lipid chain or heterochain, or at least one atom in the main chain of a saturated lipid chain or heterochain is replaced by an aromatic structure or an aromatic heterocyclic structure to form X 3 The number of chemical bonds in the main chain is ≥ 1. When the short-range connecting unit contains ketone and / or aldehyde groups, the molecular structure is Figure 3 When the molecular structure (i'), (ii'), (iii') is used to form a chemical bond with the polyol polymer; when the short-range connecting unit contains a primary amino group and / or a hydroxyl group, that is, the molecular structure is Figure 3 In the case of the molecular structures (iv′), (v′), and (vi′), it is used to form hydrogen bonds with the polyol polymer.

[0047] In this embodiment, the molecular structure (i) corresponds to a polyether polyol, which can specifically be one or more of polyethylene glycol with an average molecular weight of 200, polyethylene glycol with an average molecular weight of 300, polyethylene glycol with an average molecular weight of 400, polyethylene glycol with an average molecular weight of 600, polyethylene glycol with an average molecular weight of 800, polyethylene glycol with an average molecular weight of 1000, polyethylene glycol with an average molecular weight of 1500, polyethylene glycol with an average molecular weight of 2000, polyethylene glycol with an average molecular weight of 4000, polyethylene glycol with an average molecular weight of 6000, polyethylene glycol with an average molecular weight of 8000, polyethylene glycol with an average molecular weight of 10000, polypropylene glycol with an average molecular weight of 400, polypropylene glycol with an average molecular weight of 725, polypropylene glycol with an average molecular weight of 1000, polypropylene glycol with an average molecular weight of 2000, polypropylene glycol with an average molecular weight of 2700, polypropylene glycol with an average molecular weight of 3000, and polypropylene glycol with an average molecular weight of 4000.

[0048] In this embodiment, the molecular structure (ii) corresponds to a polyester polyol, which may be specifically one or more of poly(diethylene glycol adipate) (average molecular weight 900), poly(diethylene glycol adipate) (average molecular weight 2000), poly(hexanediol adipate) (average molecular weight 1000), poly(hexanediol adipate) (average molecular weight 2000), poly(hexanediol adipate) (average molecular weight 3000), poly(butylene adipate) (average molecular weight 600), poly(butylene adipate) (average molecular weight 1000), poly(butylene adipate) (average molecular weight 2000), poly(butylene adipate) (average molecular weight 3000), poly(butylene adipate) (average molecular weight 4000), and poly(butylene adipate) (average molecular weight 5000).

[0049] In this embodiment, the molecular structure (i′) corresponds to one or more of 2,5-hexanedione, 2,7-octanedione, and 2,9-decanedione.

[0050] In this embodiment, the molecular structure (ii′) corresponds to one or more of adipic acid dialdehyde, 1,3-butanedialdehyde, aldehyde PEG aldehyde (Mw=10000Da), aldehyde PEG aldehyde (Mw=20000Da), aldehyde PEG aldehyde (Mw=5000Da), aldehyde PEG aldehyde (Mw=6000Da), aldehyde PEG aldehyde (Mw=1000Da), aldehyde PEG aldehyde (Mw=1500Da), aldehyde PEG aldehyde (Mw=2000Da), and aldehyde PEG aldehyde (Mw=3400Da).

[0051] In this embodiment, the molecular structure (iii′) corresponds to one or more of 4-oxopentanal, 5-oxohexanal, 6-oxoheptanal, 7-oxoctanal, 8-oxononanal, 9-oxodecanal, 10-oxundecanal, and 11-oxododecanal.

[0052] In this embodiment, the molecular structure (iv′) corresponds to one or more of ethylene glycol, 1,3-propylene glycol, tripropylene glycol, 2-methyl-1,3-propanediol, dipropylene glycol, 2-methyl-2-nitro-1,3-propanediol, 1,10-decanediol, 1,8-octanediol, 1,7-heptanediol, 1,12-dodecanediol, 1,6-hexanediol, 1,5-pentanediol, 1,4-butanediol, 1,14-tetradecanediol, and 3-methyl-1,5-pentanediol.

[0053] In this embodiment, the molecular structure (v′) corresponds to one or more of oxalyl diamine, 1,8-octanediamine, p-phenylenediamine, 1,3-propylenediamine, 1,4-butylenediamine, 2,2-dimethyl-1,3-propylenediamine, 3,3′-diaminodipropylamine, adipic acid diamine, N,N′-di(2-aminoethyl)-1,3-propylenediamine, and diethylenetriamine.

[0054] In this embodiment, the molecule (vi′) can specifically be one or more of amino PEG hydroxyl (MW 5000Da) and amino PEG hydroxyl (MW 400Da).

[0055] The above molecular structures (i), (ii), (i′), (ii′), (iii′), (iv′), (v′), and (vi′) only list some of the corresponding common substances.

[0056] Please refer to Figure 4 , specifically two routes of interaction between the polyol polymer and the short-range connecting unit, R 1 ' is a methyl group or a hydrogen atom, R 2 ' is a primary amino group or a hydroxyl group, R 3 ' is a primary amino group or a hydroxyl group, route 1 represents the process of chemical bonding, route 2 represents the process of hydrogen bonding, and the black dots represent the polymethyl methacrylate polymer chain in the PMMA material, which is surrounded by a closed ring structure formed by the polyol polymer and the short-range connection unit through chemical bonding or hydrogen bonding.

[0057] Specifically, for simplicity of explanation, Figure 4 The molecular formula a shown is only a fragment of the polyol polymer in this application (the number of hydroxyl groups is temporarily selected as 4), wherein the short curve represents a chain segment of a certain length, and the specific structure refers to the corresponding description in the above polyol polymer molecules (i) and (ii). Figure 4 In the above formula, J and P represent short-range connecting units. Specifically, J represents that the short-range connecting unit is the first straight-chain compound that can produce chemical bonding, wherein R 1' represents a hydrogen atom or a methyl group, which corresponds to an aldehyde group or a ketone group respectively; P represents that the short-range connecting unit at this time is a second straight-chain compound that can produce a hydrogen bond, wherein R 2 ' is a hydroxyl group or a primary amino group, R 3 ' is a hydroxyl group or a primary amino group. Therefore, route 1 is a process of forming a chemical bond, and the polyol polymer ( Figure 4 a) In the short-range connection unit ( Figure 4 J) and the corresponding catalyst, an intramolecular acetal or ketal product as shown in b (i.e., a closed ring structure is formed), or an intermolecular acetal or ketal product as shown in c (i.e., a connection structure formed between the short-range connection unit and the polyol polymer and intercalated between the polymethyl methacrylate polymer chains is formed). Route 2 is the process of forming hydrogen bonds, and the polyol polymer ( Figure 4 a) In the short-range connection unit ( Figure 4 Under the action of P), a hydrogen bond within the polyol polymer molecule as shown in d is formed (i.e., a closed ring structure is formed), or a product of a hydroxyl-hydroxyl hydrogen bond or a primary amino-hydroxyl hydrogen bond as shown in e (i.e., a connection structure interlaced between polymethyl methacrylate polymer chains is formed through a short-range connection unit and the polyol polymer).

[0058] In the two routes proposed in this application using the interaction between polyol polymers and short-range connecting units, route 1 mainly forms a connecting structure through acetal or ketal reaction, each molecule can effectively participate in the formation of the connecting structure, the reaction process is mainly controlled by the catalyst, has a high degree of controllability, and high reaction efficiency. The hydrogen bonding mode of route 2 is mainly controlled by temperature and has extremely high efficiency.

[0059] Wherein, when the short-range connecting unit selects a second straight-chain compound containing a primary amino group and / or a hydroxyl group, the second straight-chain compound can be connected to the hydroxyl site on the polyol polymer through hydrogen bonding. The mechanism of action is as follows: Figure 4 As shown in Route 2. Add polyol polymer and short-range connection unit in sequence, stir and mix each time, let stand for a while after uniformity before adding the next one, and after all substances are added, vacuum degassing. After uniform mixing, the polyol polymer and polymethyl methacrylate prepolymer will form an adaptive entanglement state through free chain movement in methyl methacrylate solvent at room temperature. Preferably, the mass proportion of polymethyl methacrylate prepolymer is 2-10%, the mass proportion of methyl methacrylate is ≥50%, the mass proportion of initiator is ≤0.5%, the mass proportion of polyol polymer is 2-20%, and the mass proportion of short-range connection unit is 1-10%.

[0060] When the short-range connecting unit selects a first straight-chain compound containing a ketone group and / or an aldehyde group, the first straight-chain compound can be connected to the hydroxyl site on the polyol polymer by chemical bonding. The mechanism of action is as follows: Figure 4 As shown in route 1. At this time, a catalyst for catalyzing the reaction between the polyol polymer and the short-range connecting unit needs to be added in step S2. The catalyst is an acidic compound, which can be specifically selected from one or more of p-toluenesulfonic acid, hydrochloric acid, sulfuric acid, and methanesulfonic acid. Preferably, the mass proportion of the polymethyl methacrylate prepolymer is 2-10%, the mass proportion of methyl methacrylate is ≥50%, the mass proportion of the initiator is ≤0.5%, the mass proportion of the catalyst is ≤0.5%, the mass proportion of the polyol polymer is 2-20%, and the mass proportion of the short-range connecting unit is 1-10%.

[0061] When the first straight-chain compound is selected as the short-range connecting unit, the liquid phase system in step S1 may further include a functional monomer, which is an unsaturated monomer having water absorption after polymerization, preferably a weakly basic unsaturated monomer, and the functional monomer can form a copolymer chain with methyl methacrylate. The functional monomer can be specifically selected from one or more of acrylamide, methacrylamide, dimethylaminopropyl acrylamide, N-tert-butyl acrylamide, N-hydroxymethyl acrylamide, N-ethyl acrylamide, methylene bisacrylamide, N-phenyl acrylamide, N-[tris(hydroxymethyl)methyl] acrylamide, N,N-dimethyl acrylamide, N,N-diethyl acrylamide, N-phenyl methacrylamide, N-dodecyl acrylamide, N-methyl-2-acrylamide, N-(2-hydroxyethyl) acrylamide, N-isopropyl acrylamide, N,N-dimethyl methacrylamide, hexamethylene bisacrylamide, N-(butoxymethyl) acrylamide, N-isopropyl methacrylamide, N,N′-vinyl bisacrylamide, N-(4-hydroxyphenyl) methacrylamide, N-(2-hydroxypropyl) methacrylamide, N-methyl methacrylamide, N-(3-dimethylaminopropyl) methacrylamide, N-tert-butyl methacrylamide, and N-(methoxymethyl) methacrylamide.

[0062] Add polyol polymer, short-range connection unit, functional monomer and catalyst in sequence, stir and mix each time, let stand for a while before adding the next one, and after all materials are added, vacuum degassing. After mixing evenly, the polyol polymer and polymethyl methacrylate prepolymer will form an adaptive entanglement state through free chain movement in methyl methacrylate solvent at room temperature. In addition, the short-range connection unit, with the assistance of the catalyst, will undergo a low degree of preliminary chemical bonding with the appropriate hydroxyl site on the polyol polymer, which can be within the molecule of the polyol polymer or between molecules. The specific site of occurrence is related to the molecular length of the short-range connection unit and the distribution of hydroxyl groups on the polyol polymer. It is a spontaneous process based on energy stability, thereby forming a small amount of hemiacetal or hemiketal structure. Preferably, the mass proportion of polymethyl methacrylate prepolymer is 2-10%, the mass proportion of methyl methacrylate is ≥50%, the mass proportion of functional monomer is ≤9%, the mass proportion of initiator is ≤0.5%, the mass proportion of polyol polymer is 2-20%, the mass proportion of short-range connection unit is 1-10%, and the mass proportion of catalyst is ≤0.5%.

[0063] from Figure 4 As can be seen, there is a byproduct H in route 1 2 O, with the continuous generation of product b and product c, the byproduct H 2 The content of O also increases synchronously, and there is a certain risk of reverse reaction. At this time, the functional monomers polymerized in the copolymer chain have the characteristic of being hygroscopic. In the process of forming the copolymer chain, the continuously generated byproduct H 2 O is dynamically adsorbed to make H 2 O is in a non-free locked state, with properties similar to bound water, which can basically eliminate the possibility of its participation in the reverse reaction. In addition, the catalyst used in the reaction conditions of route 1 is acidic, and the functional monomer is an unsaturated monomer with weak alkalinity. During the reaction, the catalyst can be continuously and slowly neutralized by the weak alkaline functional monomer or its polymerized form, but the overall polymerization system is maintained acidic (achieved by regulating the amount of catalyst), which does not affect the positive nature of the reaction of route 1. When the reaction is close to completion, the excess acidic catalyst in the system has been neutralized and captured as much as possible, so that the risk of the reverse reaction is further reduced, which is also beneficial to the structural stability of product b and product c.

[0064] The mixing process involved in steps S1 and S2 is a common technology in the art and is not specifically limited in this application. The stirring mode, rotation speed, time, temperature and other process parameters can be appropriately selected according to the actual situation, such as mechanical stirring, a rotation speed of 100 to 1000 r / min, several minutes to tens of minutes, and room temperature.

[0065] S3. Casting, polymerizing, and allowing the polyol polymer to interact with the short-range connecting units to obtain a reinforced and toughened PMMA material.

[0066] The product in step S2 is first poured into the desired mold, and then polymerized. The process conditions of the polymerization are mainly adapted to the type of initiator used. If a thermosensitive initiator is used, the process includes a water bath or a blast air bath at 45 to 75°C for 2 to 12 hours, and a blast air bath at 105 to 135°C for 1 to 8 hours. At this polymerization temperature, not only can the reaction conditions of free radical bulk polymerization be met, but also the formation of chemical bonds or hydrogen bonds between the polyol polymer and the short-range connection units can be promoted.

[0067] If a photosensitive initiator is used, the irradiation time is 1 to 2 hours at room temperature with 220 to 380 nm ultraviolet light. If accompanied by hot air blowing at 45 to 120°C, the irradiation time can be further reduced. After the ultraviolet light irradiation initiates the polymerization of the free radical body, the heat generated by the polymerization reaction can increase the temperature, thereby satisfying the need to form chemical bonds or hydrogen bonds between the polyol polymer and the short-range connecting units.

[0068] During the polymerization process, new copolymer chains (when adding functional monomers) and a large amount of newly added polymethyl methacrylate homopolymers are formed, which together with the original polymethyl methacrylate prepolymer (polymethyl methacrylate prepolymer and newly added polymethyl methacrylate homopolymer are both polymethyl methacrylate polymer chains in PMMA materials) and polyol polymers form a deep interpenetrating network, further increasing the degree of entanglement between all polymer chains. At the same time, acetal, ketal chemical structures or hydrogen bonding effects continue to be generated (reference Figure 4 As shown), the copolymer chain and the polymethyl methacrylate polymer chain can be deeply interlocked by the closed-loop structure formed by the short-range connecting units within the polyol polymer molecule and pass through it. At the same time, the connecting structure formed by the chemical bonding or hydrogen bonding between the molecules of the polyol polymer and the short-range connecting units is interspersed between the polymethyl methacrylate polymer chains.

[0069] Figure 5 FIG. 1 is a schematic diagram of the microstructure of a reinforced and toughened PMMA material according to an embodiment. Figure 5As shown, in the reinforced and toughened PMMA material, a entangled state is formed between the polymethyl methacrylate polymer chain 100 and the polyol polymer 120. The short-range connection unit 130 is connected between the intramolecular hydroxyl sites of the polyol polymer 120 and / or between the intermolecular hydroxyl sites of the polyol polymer 120 by chemical bonding or hydrogen bonding. When the short-range connection unit 130 is connected between the intramolecular hydroxyl sites of the polyol polymer 120 by chemical bonding or hydrogen bonding, a closed-loop structure 131 surrounding the polymethyl methacrylate polymer chain 100 is formed; when the short-range connection unit 130 is connected between the intermolecular hydroxyl sites of the polyol polymer 120 by chemical bonding or hydrogen bonding, a connection structure 132 between the polyol polymers 120 is formed. In addition, the reinforced and toughened PMMA material may also include a copolymer chain 110 formed by a functional monomer and methyl methacrylate. At this time, the polymethyl methacrylate polymer chain 100, the copolymer chain 110 and the polyol polymer 120 form an entangled state, and the closed loop space 131 will also surround the copolymer chain 110 and / or the polymethyl methacrylate polymer chain 100. When the material is forced, the polymethyl methacrylate polymer chains 100 gradually tighten each other, accompanied by directional slip under the constraint of the closed loop space 131. The external force is converted into friction heat between molecular chains and dissipated in this process, which can absorb external impact energy to a large extent, and also increase the elastic deformation distance before the material structure fails, play a toughening role, and improve the toughness of the material; based on the closed loop structure 131 and the connection structure 132, it can also provide additional drag effect after tensioning, even if the main polymer chain (polymethyl methacrylate polymer chain 100) of the material is partially broken, it can still continue to play a certain mechanical connection role, thereby improving the tensile strength of the material.

[0070] By adopting the preparation method described in this embodiment, the consistent expression of PMMA-based strength and toughness is achieved, and the light transmittance can be stably maintained at more than 90%.

[0071] The performance of the PMMA material prepared by the preparation method of the present application is characterized as follows.

[0072] Preparation of the control group:

[0073] Step S1, forming a liquid phase system participating in a polymerization reaction;

[0074] The liquid phase system includes polymethyl methacrylate prepolymer, methyl methacrylate and initiator, the mass proportion of the initiator is 0.5‰, the mass proportion of the polymethyl methacrylate prepolymer is 10%, and the rest is methyl methacrylate.

[0075] Step S2, obtaining PMMA material through casting and polymerization.

[0076] The polymerization process is a water bath at 60°C for 5 hours and a forced air bath at 120°C for 3 hours.

[0077] Preparation of Sample 1:

[0078] Step S1, forming a liquid phase system participating in a polymerization reaction;

[0079] The liquid phase system includes polymethyl methacrylate prepolymer, methyl methacrylate and an initiator, and the initiator is ABVN.

[0080] Step S2, adding a polyol polymer, a short-range connection unit and a catalyst in sequence;

[0081] The molecular structure of the polyol polymer is selected from the molecular structure (i), which is a polyether polyol, specifically polyethylene glycol with an average molecular weight of 1000, the molecular structure of the short-range connecting unit is selected from the molecular structure (ii'), specifically adipaldehyde, and the catalyst is p-toluenesulfonic acid. After stirring and mixing, vacuum degassing treatment is performed. The mass proportion of the initiator is selected to be 0.5‰, the mass proportion of the polyol polymer is selected to be 20%, the mass proportion of the short-range connecting unit is selected to be 10%, the mass proportion of the catalyst is selected to be 0.5%, the mass proportion of the polymethyl methacrylate prepolymer is selected to be 10%, and the rest is methyl methacrylate.

[0082] Step S3, through casting, polymerization, and allowing the polyol polymer to interact with the short-range connection units, a reinforced and toughened PMMA material is obtained.

[0083] The polymerization process is a water bath at 60°C for 5 hours and a forced air bath at 120°C for 3 hours.

[0084] Preparation of Sample 2:

[0085] Step S1, forming a liquid phase system participating in a polymerization reaction;

[0086] The liquid phase system includes polymethyl methacrylate prepolymer, methyl methacrylate and an initiator, and the initiator is AIBN.

[0087] Step S2, adding a polyol polymer, a short-range connection unit and a catalyst in sequence;

[0088] The molecular structure of the polyol polymer is selected from the molecular structure (ii), which is a polyester polyol, specifically poly(diethylene glycol adipate) (average molecular weight 900), the molecular structure of the short-range connection unit is selected from the molecular structure (i′), specifically 2,5-hexanedione, the catalyst is hydrochloric acid, and after stirring and mixing, vacuum degassing treatment is performed. The mass proportion of the initiator is selected to be 0.1‰, the mass proportion of the polyol polymer is selected to be 2%, the mass proportion of the short-range connection unit is selected to be 1%, the mass proportion of the catalyst is selected to be 0.1%, the mass proportion of the polymethyl methacrylate prepolymer is selected to be 10%, and the rest is methyl methacrylate.

[0089] Step S3, through casting, polymerization, and allowing the polyol polymer to interact with the short-range connection units, a reinforced and toughened PMMA material is obtained.

[0090] The polymerization process is a water bath at 60°C for 5 hours and a forced air bath at 120°C for 3 hours.

[0091] Preparation of Sample 3:

[0092] Step S1, forming a liquid phase system participating in a polymerization reaction;

[0093] The liquid phase system includes polymethyl methacrylate prepolymer, methyl methacrylate and an initiator. Specifically, the initiator is BPO.

[0094] Step S2, adding a polyol polymer, a short-range connection unit, and a catalyst in sequence;

[0095] The molecular structure of the polyol polymer is selected from the molecular structure (i), which is a polyether polyol, specifically polyethylene glycol with an average molecular weight of 800, the molecular structure of the short-range connecting unit is selected from the molecular structure (iii'), specifically 5-oxohexanal, and the catalyst is methanesulfonic acid. After stirring and mixing, vacuum degassing treatment is performed. The mass proportion of the initiator is selected to be 0.25‰, the mass proportion of the polyol polymer is selected to be 10%, the mass proportion of the short-range connecting unit is selected to be 5%, the mass proportion of the catalyst is selected to be 0.25%, the mass proportion of the polymethyl methacrylate prepolymer is selected to be 10%, and the rest is methyl methacrylate.

[0096] Step S3, casting, polymerization, and allowing the polyol polymer to interact with the short-range connection units to obtain a reinforced and toughened PMMA material.

[0097] The polymerization process is a water bath at 60°C for 5 hours and a forced air bath at 120°C for 3 hours.

[0098] Preparation of Sample 4:

[0099] Step S1, forming a liquid phase system participating in a polymerization reaction;

[0100] The liquid phase system includes polymethyl methacrylate prepolymer, methyl methacrylate and an initiator. Specifically, the initiator is AIBN.

[0101] Step S2, adding a polyol polymer and a short-range connection unit in sequence;

[0102] The molecular structure of the polyol polymer is selected from the molecular structure (ii), which is a polyester polyol, specifically polyhexanediol adipate (average molecular weight 1000), and the molecular structure of the short-range connecting unit is selected from the molecular structure (iv′), specifically 1,6-hexanediol. After stirring and mixing, vacuum degassing treatment is performed. The mass proportion of the initiator is selected to be 0.2‰, the mass proportion of the polyol polymer is selected to be 8%, the mass proportion of the short-range connecting unit is selected to be 4%, the mass proportion of the polymethyl methacrylate prepolymer is selected to be 10%, and the rest is methyl methacrylate.

[0103] Step S3, casting, polymerization, and allowing the polyol polymer to react with the short-range connection units to obtain a reinforced and toughened PMMA material.

[0104] The polymerization process is a water bath at 60°C for 5 hours and a forced air bath at 120°C for 3 hours.

[0105] Preparation of Sample 5:

[0106] Step S1, forming a liquid phase system participating in a polymerization reaction;

[0107] The liquid phase system includes polymethyl methacrylate prepolymer, methyl methacrylate and an initiator. Specifically, the initiator is ABVN.

[0108] Step S2, adding a polyol polymer and a short-range connection unit in sequence;

[0109] The molecular structure of the polyol polymer is selected from the molecular structure (i), which is a polyether polyol, specifically polypropylene glycol with an average molecular weight of 1000, and the molecular structure of the short-range connecting unit is selected from the molecular structure (v′), specifically 1,8-octanediamine. After stirring and mixing, vacuum degassing treatment is performed. The mass proportion of the initiator is selected to be 0.4‰, the mass proportion of the polyol polymer is selected to be 16%, the mass proportion of the short-range connecting unit is selected to be 8%, the mass proportion of the polymethyl methacrylate prepolymer is selected to be 10%, and the rest is methyl methacrylate.

[0110] Step S3, casting, polymerization, and allowing the polyol polymer to interact with the short-range connection units to obtain a reinforced and toughened PMMA material.

[0111] The polymerization process is a water bath at 60°C for 5 hours and a forced air bath at 120°C for 3 hours.

[0112] Preparation of Sample 6:

[0113] Step S1, forming a liquid phase system participating in a polymerization reaction;

[0114] The liquid phase system includes polymethyl methacrylate prepolymer, methyl methacrylate and an initiator. Specifically, the initiator is BPO.

[0115] Step S2, adding a polyol polymer and a short-range connection unit in sequence;

[0116] The molecular structure of the polyol polymer is selected from the molecular structure (ii), which is a polyester polyol, specifically polybutylene adipate (average molecular weight 1000), and the molecular structure of the short-range connecting unit is selected from the molecular structure (vi′), specifically amino PEG hydroxyl (MW 400Da). After stirring and mixing, vacuum degassing treatment is performed. The mass proportion of the initiator is selected to be 0.3‰, the mass proportion of the polyol polymer is selected to be 12%, the mass proportion of the short-range connecting unit is selected to be 6%, the mass proportion of the polymethyl methacrylate prepolymer is selected to be 10%, and the rest is methyl methacrylate.

[0117] Step S3, casting, polymerization, and allowing the polyol polymer to interact with the short-range connection units to obtain a reinforced and toughened PMMA material.

[0118] The polymerization process is a water bath at 60°C for 5 hours and a forced air bath at 120°C for 3 hours.

[0119] Sample preparation and result analysis

[0120] The size of the control group and samples 1 to 6 are all 50×50×4mm, and UV-Vis spectrum characterization is performed. The transmittance test in the visible light region is based on "GB / T 7134-2008 Casting Industrial Organic Glass Sheet", and the light transmittance data at a wavelength of 420nm is taken. The light transmittance of the control group is 93%, and the light transmittance of samples 1 to 6 is 91%, 92%, 91%, 92%, 92%, 91% (see Figure 6 and Table 1), similar to the control group, with excellent transparency.

[0121] The basic physical properties (tensile strength, elongation at break, simply supported beam unnotched impact strength and Barcol hardness) were characterized according to GB / T 7134-2008 Casting Industrial Organic Glass Sheet and GB / T 3854-2017 Test Method for Barcol Hardness of Reinforced Plastics. The data sample for each characterization item was ≥20. The results showed that compared with the basic physical properties of the control group (see Table 1), the tensile strength index and impact strength index of samples 1 to 6 were significantly improved, while the light transmittance, elongation at break and Barcol hardness were consistent with the control group.

[0122] Table 1. Results and statistics

[0123] Note: w The impact strength refers specifically to the simply supported beam unnotched impact strength.

[0124] The above embodiments are merely illustrative of the principles and effects of the present application and are not intended to limit the present application. Anyone familiar with the technology may modify or change the above embodiments without violating the spirit and scope of the present application. Therefore, all equivalent modifications or changes made by a person of ordinary skill in the art without departing from the spirit and technical ideas disclosed in the present application shall still be covered by the claims of the present application.

Claims

1. A method for preparing a reinforced and toughened PMMA material, characterized in that: The following steps are involved: S1. forming a liquid phase system, the liquid phase system comprising a polymethyl methacrylate prepolymer, methyl methacrylate and an initiator; S2. sequentially adding a polyol polymer and a short-range connection unit to the liquid phase system; S3. Casting, polymerization, and allowing the polyol polymer to interact with the short-range connection unit to obtain a reinforced toughened PMMA material; Wherein, the polyol polymer is selected from polyether polyol or polyester polyol, wherein the molecular structure of the polyether polyol is molecular structure (i); and the molecular structure of the polyester polyol is molecular structure (ii): ， R1 is C α H 2α (α is an integer ≥ 1), n1 is an integer ≥ 1; R2 is C β H 2β (β is an integer ≥ 1), R3 is C γ H 2γ O z (γ is an integer ≥1, z is an integer ≥0 and z<γ), n2 is an integer ≥1; The molecular structure of the short-range connection unit is at least one of the molecular structures (i´) to (vi´): ， Among them, X3 is a straight chain structure; When the molecular structure of the short-range connection unit is the molecular structure (i´), (ii´) or (iii´), a catalyst for catalyzing the reaction between the polyol polymer and the short-range connection unit is further added in the S2 step, the liquid phase system further comprises a functional monomer, the functional monomer is an unsaturated monomer having water absorption after polymerization, the functional monomer is used to form a copolymer chain with the methyl methacrylate, the functional monomer is a weakly basic unsaturated monomer, the catalyst is an acidic compound, the mass proportion of the polymethyl methacrylate prepolymer is 2-10%, the mass proportion of the methyl methacrylate is ≥50%, the mass proportion of the functional monomer is ≤9%, the mass proportion of the initiator is ≤0.5%, the mass proportion of the polyol polymer is 2-20%, the mass proportion of the short-range connection unit is 1-10%, and the mass proportion of the catalyst is ≤0.5%; When the molecular structure of the short-range connection unit is the molecular structure (iv´), (v´) or (vi´), the mass proportion of the polymethyl methacrylate prepolymer is 2-10%, the mass proportion of the methyl methacrylate is ≥50%, the mass proportion of the initiator is ≤0.5%, the mass proportion of the polyol polymer is 2-20%, and the mass proportion of the short-range connection unit is 1-10%; When the initiator is a thermosensitive initiator, the step S3 comprises: First, place in a water bath or a forced air bath at 45-75 °C for 2-12 h, and then place in a forced air bath at 105-135 °C for 1-8 h; When the initiator is a photosensitive initiator, the S3 step comprises: Irradiate with 220~380 nm ultraviolet light for 1~2 h at room temperature.

2. The method for preparing the reinforced and toughened PMMA material according to claim 1, characterized in that: The S2 step includes: adding a polyol polymer; After stirring to mix, add the short-range connection unit.

3. A reinforced and toughened PMMA material, characterized in that: The reinforced and toughened PMMA material is prepared by the preparation method of any one of claims 1 or 2.

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