Heat-resistant agent for transparent material and preparation process therefor

Abstract

A heat-resistant agent for a transparent material and a preparation process therefor. The heat-resistant agent consists of the following raw materials in parts by weight: 30-75 parts of an acrylate-based monomer, 10-30 parts of an aromatic vinyl monomer, 5-40 parts of a maleimide substance, and 0.3-0.5 parts of an initiator. The heat-resistant agent is prepared by means of a suspension polymerization process. The prepared heat-resistant agent exhibits a good thermal stability and glass transition temperature, and the addition of a transparent plastic does not affect the transparency thereof. In addition, the preparation process is simple and environmentally friendly, and has a low cost; and the heat-resistant agent can be applied to engineering plastics having requirements for both transparency and heat resistance.

Description

A heat-resistant agent for transparent materials and its preparation method Technical Field

[0001] This invention belongs to the field of polymer material modification and relates to a heat-resistant agent for transparent materials and its preparation method. Background Technology

[0002] Transparent plastics, including PMMA, PS, PC, and transparent ABS, are generally used in insulating parts, decorative items, and optical instruments due to their excellent transparency and good mechanical properties. PMMA is the most commonly used transparent material in industry, possessing excellent optical and mechanical properties, low cost, and weather resistance. However, its poor heat resistance limits its application in the automotive, medical device, and electronics industries. Therefore, improving the heat resistance of PMMA while maintaining its transparency and expanding its application areas has been a ongoing research topic. Technical issues

[0003] Currently, due to the excellent heat resistance of the five-membered ring in the imide structure, most heat-resistant agents on the market are maleimide copolymers. However, when most maleimide copolymer heat-resistant agents are added to transparent plastics, such as PMMA, and extruded and granulated, their transparency is reduced, making it impossible to simultaneously meet the requirements of heat resistance and transparency. Conventionally, in industrial applications, commonly used transparent materials generally require a light transmittance of over 90% for optimal application.

[0004] Moreover, existing maleimide copolymer heat-resistant agents use solution polymerization, which is not environmentally friendly and has a complicated process, making it unsuitable for large-scale mass production. Technical solutions

[0005] The purpose of this invention is to address the shortcomings of existing technologies by providing a heat-resistant agent for transparent materials and its preparation method. The heat-resistant agent produced using this invention not only exhibits excellent heat resistance but also produces transparent bead-like particles, making it suitable for modified transparent materials requiring both high heat resistance and maintained transparency.

[0006] The objective of this invention is achieved through the following techniques:

[0007] A heat-resistant agent for transparent materials, wherein the raw materials for preparing the heat-resistant agent for transparent materials include acrylate monomers, styrene-based substances, and maleimide-based substances.

[0008] In this invention, the acrylate monomers include one or more of methyl methacrylate, ethyl methacrylate, butyl methacrylate, methyl acrylate, or butyl acrylate; the styrene substances include aromatic vinyl monomers, specifically, aromatic vinyl monomers include one or more of styrene, methylstyrene, and ethylstyrene; the maleimide substances include one or more of N-phenylmaleimide, N-cyclohexylmaleimide, and bismaleimide monomers.

[0009] This invention discloses a method for preparing the aforementioned heat-resistant agent for transparent materials, comprising the following steps: the raw materials for preparing the heat-resistant agent for transparent materials are obtained through a polymerization reaction. Further, acrylate monomers, styrene-based substances, and maleimide-based substances are mixed and then subjected to a polymerization reaction to obtain the heat-resistant agent for transparent materials.

[0010] In this invention, the weight ratio of acrylate monomers, styrene compounds, and maleimide compounds is (30-75):(10-30):(5-40). Preferably, the weight ratio is (40-65):(10-20):(20-40). More preferably, the weight ratio is (50-65):(10-20):(20-35), and even more preferably, the weight ratio is (55-65):(12-18):(20-30), such as 55:15:30, 65:15:20, or other ratios within this range.

[0011] In this invention, the polymerization reaction is an initiation polymerization reaction, and the initiator used includes one or more of azo initiators and peroxide initiators; the polymerization reaction temperature is 50-100℃, and the time is 1-10h; preferably, the polymerization reaction temperature is 55-90℃, and the time is 2-8h; more preferably, the polymerization reaction temperature is 60-80℃, and the time is 3-6h. Further, after the polymerization reaction, a curing process is performed to obtain a heat-resistant agent for transparent materials. The curing is performed at 80-105℃ for 0.5-5h; preferably, the curing is performed at 90-95℃ for 1-2h.

[0012] In this invention, the polymerization reaction is carried out in the presence of a molecular weight regulator; the molecular weight regulator is selected from 2,4-diphenyl-4-methyl-1-pentene, tert-dodecyl mercaptan, and isooctyl 3-mercaptoacrylate. The amount of the molecular weight regulator used is 0.05-0.5% of the weight of the acrylate monomer, styrene, and maleimide, preferably 0.05-0.2%, more preferably 0.08-0.12%, such as 0.08%, 0.09%, 0.1%, 0.11%, 0.12%, or any value within the range.

[0013] In this invention, water is used as the solvent for the polymerization reaction. This invention employs suspension polymerization, which solves the problems of existing solution polymerization processes being environmentally unfriendly, cumbersome, and unsuitable for large-scale mass production. Furthermore, the polymerization produced by this invention can yield transparent bead-like particles, making it suitable for modified transparent materials that require both high heat resistance and maintained transparency.

[0014] As an example, acrylate monomers, styrene-based substances, maleimide-based substances, and water are mixed, and then an initiator and a molecular weight regulator are added. The mixture undergoes a polymerization reaction and is then cured to obtain a heat-resistant agent for use in transparent materials, which is in the form of transparent particles.

[0015] This invention discloses the application of the above-mentioned heat-resistant agent for transparent materials in the preparation or as a plastic modifier.

[0016] This invention discloses the application of the above-mentioned heat-resistant agent for transparent materials in the preparation of plastics. Preferably, the plastic includes transparent plastics, including PMMA, PC, transparent ABS, transparent PS, etc.; for example, the above-mentioned heat-resistant agent is applied to transparent materials such as PMMA, PC, transparent ABS, PS, etc.

[0017] This invention discloses a plastic, the raw materials of which include the heat-resistant agent used for transparent materials mentioned above; specifically, the heat-resistant agent used for transparent materials is added as a modifier to the raw materials for preparing the plastic to obtain a plastic product. Beneficial effects

[0018] Compared with the prior art, the present invention has the following effects:

[0019] 1. This system uses suspension polymerization to prepare heat-resistant agents. These heat-resistant agents have both excellent heat resistance and good transparency, meeting the market requirements for transparent heat-resistant agents.

[0020] 2. The preparation process of this system is simple and environmentally friendly, and it can be mass-produced;

[0021] 3. This process can control the molecular weight and distribution of polymers, resulting in polymers with a narrow molecular weight distribution;

[0022] 4. This heat-resistant agent can be directly applied to the heat-resistant modification of PMMA, exhibiting good compatibility and heat resistance, which can expand the application field of PMMA; it can also be applied to the heat-resistant modification process of other transparent materials to improve the application performance of the materials. Attached Figure Description

[0023] Other features, objects, and advantages of the present invention will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings.

[0024] Figure 1 shows the glass transition temperature of the heat-resistant polymer A2.

[0025] Figure 2 shows the glass transition temperature of the heat-resistant polymer B1.

[0026] Figure 3 shows the glass transition temperature of the heat-resistant polymer B2.

[0027] Figure 4 shows the infrared spectrum of the heat-resistant polymer A2.

[0028] Figure 5 shows the appearance of tablets after compression with different heat-resistant agents.

[0029] Figure 6 shows the appearance of acrylic after modification with different heat-resistant agents. Embodiments of the present invention

[0030] The heat-resistant agent described in this invention is a copolymer obtained by polymerization of acrylate monomers, styrene-based substances, and maleimide-based substances with conventional additives (such as initiators and molecular weight regulators). Specifically, this invention discloses a method for preparing the above-mentioned heat-resistant agent for transparent materials, comprising the following steps:

[0031] (1) Mix acrylate monomers, aromatic vinyl monomers and maleimide substances in a certain proportion, add water, stir evenly, add initiator and molecular weight regulator, the polymerization reaction temperature is 60-80℃, and the constant temperature reaction time is 3-6h;

[0032] (2) After the isothermal reaction is completed, the product is aged at 90-95℃ for 1-2 hours, filtered and dried to obtain a heat resistant agent for transparent materials. It is a random copolymer with an imine structure. The product is transparent colorless / light yellow bead-like particles. The glass transition temperature of the heat resistant agent is between 150-200℃.

[0033] In this invention, the weight ratio of acrylate monomers, styrene substances, maleimide substances, and water is 1:(0.5-5). Preferably, the weight ratio of acrylate monomers, styrene substances, maleimide substances, and water is 1:(1-3). More preferably, the weight ratio of acrylate monomers, styrene substances, maleimide substances, and water is 1:(1.5-2.5).

[0034] In this invention, the initiator includes one of azo or peroxide initiators; the amount of initiator used is 0.1-1% of the weight of the acrylate monomer, styrene, and maleimide, preferably 0.2-0.6%, more preferably 0.2-0.5%, such as 0.2%, 0.3%, 0.4%, 0.5%, or any value within the range.

[0035] The heat-resistant agent described in this invention is applied to transparent materials, such as PMMA, PC, transparent ABS, and PS. As an application example, the transparent material, antioxidant, and the aforementioned heat-resistant agent are mixed evenly to obtain a premix. The premix is ​​then placed in a screw extruder and extruded to form granules. The modified heat-resistant transparent material has a transparency almost equivalent to that of pure plastic.

[0036] The present invention will be described in detail below with reference to specific embodiments. These embodiments will help those skilled in the art to further understand the present invention, but do not limit the invention in any way. It should be noted that those skilled in the art can make several modifications and improvements without departing from the concept of the present invention. These all fall within the protection scope of the present invention. The raw materials used in the present invention are conventional products in the art, and the specific preparation operations and performance tests are all conventional techniques. Unless otherwise specified, the parts referred to below are parts by weight, with each part being 1 kilogram.

[0037] The preparation method of the transparent heat-resistant agent of this invention is as follows: Acrylic monomers, styrene-based substances, and maleimide-based substances are mixed in a certain weight ratio and added to a polymerization reactor. Water is added, and the mixture is stirred evenly. An initiator and a molecular weight regulator are added. The polymerization reaction temperature is 60–80°C, and the constant temperature reaction time is 3–6 hours. After the constant temperature reaction is completed, the temperature is further increased to 90–95°C and cured for 1–2 hours. The mixture is then filtered and dried to obtain transparent, light yellow bead-like particles. This polymer is a random copolymer with excellent heat resistance. Adding it to transparent plastics for granulation modification yields transparent heat-resistant modified plastics. Example 1

[0038] Weigh out 65 parts by weight of methyl methacrylate (MMA), 15 parts by weight of styrene (ST), and 20 parts by weight of N-phenylmaleimide (NPMI), mix them evenly, add 200 parts by weight of water, stir for 30 minutes, then add 0.3 parts by weight of AIBN and 0.1 parts by weight of tert-dodecyl mercaptan, react at 65°C for 5 hours, after the reaction is completed, react at 95°C for 1.5 hours, then cool naturally to room temperature, collect the reactants, filter and dry to obtain transparent light yellow bead-like particles A1. Example 2

[0039] Weigh out 55 parts MMA, 15 parts ST, and 30 parts NPMI by weight and mix them evenly. Add 200 parts water and stir for 30 minutes. Then add 0.3 parts AIBN and 0.1 parts tert-dodecyl mercaptan. React at 65°C for 5 hours. After the reaction is complete, react at 95°C for 1.5 hours. Then cool naturally to room temperature, collect the reactants, filter and dry to obtain transparent light yellow bead-like particles A2. Example 3

[0040] Weigh out 45 parts MMA, 15 parts ST, and 40 parts NPMI by weight and mix them evenly. Add 200 parts water and stir for 30 minutes. Then add 0.3 parts AIBN and 0.1 parts tert-dodecyl mercaptan. React at 65°C for 5 hours. After the reaction is complete, react at 95°C for 1.5 hours. Then cool naturally to room temperature, collect the reactants, filter and dry to obtain transparent light yellow bead-like particles A3. Comparative Example 1

[0041] Weigh out 10 parts MMA, 60 parts ST, and 30 parts NPMI by weight and mix them evenly. Add 200 parts water and stir for 30 minutes. Then add 0.3 parts AIBN and 0.1 parts tert-dodecyl mercaptan. React at 65°C for 5 hours. After the reaction is complete, react at 95°C for 1.5 hours. Then cool naturally to room temperature, collect the reactants, filter and dry to obtain transparent light yellow bead-like particles B1. Comparative Example 2

[0042] Weigh out 10 parts MMA, 50 parts ST, and 40 parts NPMI by weight and mix them evenly. Add 200 parts water and stir for 30 minutes. Then add 0.3 parts AIBN and 0.1 parts tert-dodecyl mercaptan. React at 65°C for 5 hours. After the reaction is complete, react at 95°C for 1.5 hours. Then cool naturally to room temperature, collect the reactants, filter and dry to obtain transparent light yellow bead-like particles B2. Comparative Example 3

[0043] The commercially available competitor, SMA resin, is a styrene-maleic anhydride copolymer, consisting of slightly yellow, transparent particles, designated as B3. Comparative Example 4

[0044] The commercially available competitor, SMI resin, is a styrene-N-phenylmaleimide copolymer, a slightly yellow powder particle, designated as B4. Comparative Example 5

[0045] The commercially available competitor, BP-356M resin, is a styrene-methyl methacrylate-maleic anhydride terpolymer, with natural-colored, high-transparency particles, designated as B5. Test performance

[0046] Infrared testing: Fourier transform infrared spectrometer was used for testing;

[0047] Thermogravimetric analysis: The test was conducted according to ASTM D6370-99 standard, using TGA, with a heating rate of 20℃ / min, N2 atmosphere, and the initial thermal decomposition temperature was taken as 5% of the weight loss.

[0048] DSC test: Tested according to ASTM E1356 standard, heating rate 10℃ / min, N2 atmosphere;

[0049] Vicat softening point: The test was conducted in accordance with ISO 306 standard;

[0050] Color haze meter: Tested according to ASTM D1003 standard;

[0051] The polymers prepared in the examples and comparative examples were subjected to performance tests, and the results are shown in Table 1.

[0052] Table 1. Performance test results of polymers prepared in Examples 1-3 and Comparative Examples 1-3

[0053]

[0054] Examples 1-3 are heat-resistant copolymers with different NPMI contents. As shown in Table 1, the glass transition temperature (Tg) gradually increases with the increase of NPMI content, and there is only one Tg value. As shown in Figure 1, it is the DSC curve of the heat-resistant polymer A2 of the present invention. Although the raw materials of Comparative Examples 1 and 2 are the same as those of the examples, which are also heat-resistant copolymers with different NPMI contents, the difference in proportion results in two Tg peaks. The composition of the polymer is not uniform and it is a defective product. See Figures 2 and 3, which are the DSC curves of polymers B1 and B2, respectively.

[0055] As shown in Figure 4, the infrared spectrum of the heat-resistant polymer A2 indicates that the MMA-ST-NPMI terpolymer has been successfully synthesized, with values ​​of 1777 and 1705 cm⁻¹. -1 V at the location C=O and 1180cm -1 V C-N This is the characteristic absorption peak of NPMI.

[0056] Comparative Example 3 is a commercially available heat resistant agent that is well applied in production. According to the Tg value, Example 2 can meet the market's application requirements for heat resistant agents, and the thermal decomposition temperature of the polymer is above 300°C, which can meet the granulation processing technology of transparent plastics. Application Examples

[0057] The composition and formulation of the polymer in this embodiment are shown in Table 2. The preparation method is as follows: The above heat resistant agent is mixed with PMMA and antioxidants (1010, 168, in equal proportion) in a high-speed mixer to obtain a premix; the premix is ​​put into a twin-screw extruder and extruded and granulated to obtain the final product, which is a conventional method.

[0058] Table 2 Comparative and Example Formulation Ratios (by weight) for PMMA Application Evaluation

[0059]

[0060] As shown in Figure 5, the particles from Examples 2 and Comparative Examples 3-5 were pressed into sheets. Visually, except for Comparative Example 4 which had the worst transparency, the other pressed sheets had comparable transparency. However, when the comparative examples were used with PMMA or other matrices, the transmittance of the modified materials decreased to less than 90%, as shown in Table 2. Visually, the PMMA modified in Example 2 of this invention exhibited the best transmittance, as shown in Figure 6, with low haze (7.5%). Simultaneously, the improvement in thermal properties was relatively small. This indicates that adding a heat-resistant agent containing MMA to the copolymer does not necessarily improve heat resistance while maintaining transmittance.

[0061] The application evaluation results are shown in Table 2. The results indicate that:

[0062] Examples 4-6 show samples with 10 parts of A1, A2, or A3 added, all with a light transmittance of over 90%. Therefore, the addition of this heat-resistant polymer has almost no impact on the transparency of PMMA.

[0063] Comparative Examples 6-10, with the addition of the same proportions of B1, B2, B3, B4, and B5, showed a decrease in light transmittance compared to the examples. Under the same NPMI content, the haze of the comparative examples was higher than that of the examples. Therefore, the polymerization ratio of MMA to ST has a certain influence on the transparency of PMMA heat-resistant modification. The light transmittance of Comparative Examples 8-10 was lower than that of Examples 4-6, while the haze was higher than that of the examples. Therefore, the heat-resistant agent of this invention has advantages over commercially available heat-resistant agents, as it can improve the heat resistance of PMMA without affecting its transparency.

[0064] Extended Applications

[0065] The obtained heat resistant agent A2 (added at 10 wt%) was mixed with PC, transparent ABS, and transparent PS in a high-speed mixer (with the addition of conventional antioxidants, 0.3%-0.4%, 1010, 168, etc., in equal proportions) to obtain a premix. The premix was then placed in a twin-screw extruder for extrusion granulation, followed by conventional tableting. The resulting heat-resistant modified plastic also has excellent light transmittance and can replace pure plastics for industrial applications.

[0066] The specific embodiments of the present invention have been described above. It should be understood that the present invention is not limited to the specific embodiments described above, and those skilled in the art can make various modifications or variations within the scope of the claims, which do not affect the essence of the present invention.

Claims

1. A heat-resistant agent for transparent materials, characterized in that, The raw materials for preparing the heat-resistant agent used in transparent materials include acrylate monomers, styrene-based substances, and maleimide-based substances.

2. The heat-resistant agent for transparent materials according to claim 1, characterized in that, The acrylate monomers include one or more of methyl methacrylate, ethyl methacrylate, butyl methacrylate, methyl acrylate, or butyl acrylate; the styrene compounds include one or more of aromatic vinyl monomers; and the maleimide compounds include one or more of N-phenylmaleimide, N-cyclohexylmaleimide, and bismaleimide monomers.

3. The heat-resistant agent for transparent materials according to claim 1, characterized in that, The weight ratio of acrylate monomers, styrene compounds and maleimide compounds is (30-75):(10-30):(5-40).

4. The method for preparing the heat-resistant agent for transparent materials according to claim 1, characterized in that, The raw materials for preparing heat-resistant agents for transparent materials are obtained through polymerization reactions.

5. The method for preparing the heat-resistant agent for transparent materials according to claim 4, characterized in that, The polymerization reaction is an initiation polymerization reaction, and the initiator includes one or more of azo initiators and peroxide initiators; the polymerization temperature is 60-80℃ and the time is 3-6h.

6. The method for preparing the heat-resistant agent for transparent materials according to claim 4, characterized in that, After polymerization, the mixture is cured to obtain a heat-resistant agent for use in transparent materials.

7. The method for preparing the heat-resistant agent for transparent materials according to claim 4, characterized in that, The polymerization reaction is carried out in the presence of a molecular weight regulator; water is used as the solvent in the polymerization reaction.

8. The use of the heat-resistant agent for transparent materials as described in claim 1 in the preparation or use of plastic modifiers.

9. A plastic, characterized in that, The raw materials for preparing the plastic include the heat-resistant agent for transparent materials as described in claim 1.

10. The use of the heat-resistant agent for transparent materials as described in claim 1 in the preparation of plastics.

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