Acrylic resin composition, preparation method thereof and optical-grade resin forming body

Abstract

The invention provides an acrylic resin composition, a preparation method thereof and an optical-grade resin molded body. The acrylic resin composition comprises (methyl) acrylic resin A and imide resin B, (methyl) acrylic resin A is used as raw material resin, an amination reagent is added for amination modification, and the carboxyl content in a polymer is reduced, so that the dimensional stability and the water vapor barrier property of the resin in a humid and hot environment are improved on the basis of keeping the heat resistance of the resin. In addition, an amide reaction which is lower in reaction activation energy and easier to react is adopted to replace an amine-ester exchange reaction, so that the energy consumption in the modification reaction process is reduced, and the reaction conversion rate is increased.

Description

Technical Field

[0001] This invention relates to the field of polymers, and more specifically to acrylic resin compositions and their optical applications. Background Technology

[0002] Polymethyl methacrylate (PMMA) resin is widely used in traditional automotive lighting and light guides due to its excellent optical transmittance (over 92%), surface gloss, and processability. However, with the rapid development of the new energy vehicle industry towards intelligence, lightweighting, and high performance, the heat resistance requirements for PMMA optical materials are gradually increasing. Furthermore, in the optoelectronic display field, the demand for PMMA optical films to replace TAC films as protective films for polarizers is expanding, placing higher demands on the moisture and heat resistance of PMMA materials.

[0003] Patent CN103459490B uses a copolymerization method of methyl methacrylate, phenyl methacrylate, and methacrylic acid to prepare heat-resistant PMMA resin to address the problem of deteriorating optical film performance at high temperatures. However, the introduction of a large amount of methacrylic acid monomers into the polymer leads to an increase in the content of carboxylic acid groups and enhanced water absorption. This makes the product highly susceptible to problems such as bubbles and watermarks during injection molding or casting, severely impacting the yield rate. Furthermore, the color stability of aromatic products is poor, making them prone to aging and yellowing. The benzene ring units in phenyl methacrylate exhibit strong absorption of near-ultraviolet light, which is detrimental to the optical performance of the molded product.

[0004] Patent CN103380175B increases the glass transition temperature of traditional PMMA by chemically modifying it with imide. However, the amine-ester exchange reaction between amines and ester groups on the polymer backbone is difficult and slow, necessitating raising the reactor temperature to a maximum of 280°C to promote the amine-ester exchange. At this high temperature, PMMA resin is highly susceptible to oxidation, yellowing, and degradation, and the excessively high process temperature also leads to persistently high energy consumption during continuous production.

[0005] Patent CN1140547C describes a method that pre-mixes 5:1 to 50:1 siloxane compounds into methacrylate monomers to generate nano-silica in situ within PMMA materials, resulting in nano-silica-modified PMMA optical fiber materials with improved mechanical and temperature resistance properties. While this method is mild, it involves polymer swelling and solvent removal processes, making the process lengthy and the siloxane compounds difficult to react completely, thus making it unsuitable for large-scale industrial production.

[0006] Patent CN116515016A utilizes the reaction of PMMA resin obtained from the polymerization of methyl methacrylate monomers with an imidizing agent to prepare PMMA resin containing an imide structure, attempting to solve the problems of low heat resistance and inherent negative birefringence of ordinary PMMA in the prior art. While the patent does not explicitly disclose specific experimental data such as imidization rate and glass transition temperature in its embodiments, the reaction pressure of 20 MPa suggests that the imidization reaction efficiency of this method is not high, requiring high pressure to improve mixing and reaction efficiency. Since imidizing agents are generally flammable and have a foul odor, high-pressure reactions place high demands on the pressure-resistant design of the reactor, leading to high equipment manufacturing costs and significant on-site safety management risks in actual industrial production.

[0007] CN105492473A uses aniline and other amination reagents with cyclic structures to react with methacrylate resins to prepare resins containing cycloalkyl or aromatic imide structures, and further prepares optical films with low birefringence properties. Due to the large steric hindrance of cycloalkylamines and aromatic amines, this patent has to increase the amount of amine reagent added to increase the imide content in the resin. This method results in low efficiency of the amination reagent, difficulty in devolatilization, and residual aniline and other amination reagents easily causing the resin to yellow and become brittle during processing. Summary of the Invention

[0008] This invention relates to an acrylic resin composition, its preparation method, and an optical-grade resin molded article. Using a special copolymer acrylic resin containing (meth)acrylic acid structural units as raw material, amination modification is performed using the carboxylic acid groups in the polymer as reaction sites to obtain an acrylic resin composition mainly composed of imide resin B and containing (meth)acrylic acid resin A. Compared with the traditional amination process involving the amination of methyl ester groups in PMMA resin by amination reagents, the amide reaction between carboxylic acid groups and amination reagents requires a lower activation energy, is easier to proceed, and can achieve a higher reaction conversion rate with a shorter reaction residence time. Simultaneously, the (meth)acrylic acid structural units and glutaric anhydride structural units, which provide heat resistance, are converted into glutarimide structural units and (meth)acrylamide structural units after amination modification. While maintaining a rigid cyclic structure in the main chain, this reduces the problems of excessively high molecular chain polarity, resin water absorption, and poor hygrothermal resistance of the resin product caused by carboxylic acid and anhydride groups.

[0009] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0010] In a first aspect, the present invention provides an acrylic resin composition comprising (meth)acrylic resin A and imide resin B; wherein (meth)acrylic resin A comprises repeating units shown in general formula (1) and general formula (2), and imide resin B comprises repeating units shown in general formula (1), general formula (2), general formula (3), and general formula (4).

[0011] The general formula (1) is:

[0012]

[0013] The general formula (2) is:

[0014]

[0015] The general formula (3) is:

[0016]

[0017] The general formula (4) is:

[0018]

[0019] R1 and R2 are each independently selected from hydrogen or straight-chain or branched alkyl groups having 1 to 4 carbon atoms, preferably R1 is a hydrogen atom and R2 is a methyl group; R3 is selected from straight-chain or branched alkyl groups having 1 to 10 carbon atoms, preferably straight-chain or branched alkyl groups having 1 to 3 carbon atoms, more preferably methyl or ethyl; R4 is selected from hydrogen, branched or unbranched alkyl groups having 1 to 12 carbon atoms, or cycloalkyl groups, preferably hydrogen, straight-chain alkyl groups having 1 to 3 carbon atoms, or branched cycloalkane groups having 3 to 12 carbon atoms, more preferably hydrogen, methyl, ethyl, propyl, or cyclohexyl.

[0020] In one embodiment of the present invention, the acrylic resin composition comprises (meth)acrylic resin A with a glass transition temperature greater than or equal to 124°C and imide resin B with a glass transition temperature greater than or equal to 125°C.

[0021] In one embodiment of the present invention, the (meth)acrylic resin A in the acrylic resin composition accounts for 5% wt to 80% wt, and the imide resin B in the acrylic resin composition accounts for 20% wt to 95% wt.

[0022] In a preferred embodiment of the present invention, in the (meth)acrylic resin A, the molar percentage of the repeating unit represented by general formula (1) is 90% to 98%, and the molar percentage of the repeating unit represented by general formula (2) is 2% to 10%, based on the sum of the molar amounts of repeating units in general formula (1) and general formula (2).

[0023] In a preferred embodiment of the present invention, in the imide resin B, the molar percentage of the repeating unit represented by general formula (1) is 65% to 98%, the molar percentage of the repeating unit represented by general formula (2) is 0% to 5%, the molar percentage of the repeating unit represented by general formula (3) is 0.99% to 25%, and the molar percentage of the repeating unit represented by general formula (4) is 0.01% to 5%, based on the molar amounts of repeating units in general formulas (1), (2), (3), and (4).

[0024] In this invention, the molar content of the repeating unit represented by general formula (2) in (meth)acrylic resin A and imide resin B needs to be controlled. On the one hand, this invention relies on the carboxyl unit in general formula (2) as the reaction site. Increasing the molar content of the repeating unit represented by general formula (2) will help the amide reaction to occur and improve the reaction conversion rate. On the other hand, an excessively high number of carboxyl units in the resin will lead to increased resin polarity and water absorption, resulting in increased resin brittleness, easy shrinkage under heat, and poor dimensional stability under humid and hot conditions. In addition, (meth)acrylic resin is more prone to degradation and gas production under high-temperature processing conditions than ordinary (meth)acrylic ester resin, which is not conducive to the processing performance of resin products. Therefore, in this invention, the molar content of the repeating unit represented by general formula (2) in the molecular structure of (meth)acrylic resin A is limited to less than 10%. In particular, using (meth)acrylic resin A with strict structural control as the base resin, through efficient imide reaction, the molar content of the repeating unit represented by general formula (2) in imide resin B will be less than or equal to 5%.

[0025] The present invention also provides a method for preparing the above-mentioned acrylic resin composition, comprising the following steps:

[0026] S1. Polymer preparation: Mix monomers, initiators and / or chain transfer agents, and optional other additives as shown in general formula (5) and general formula (6), carry out polymerization reaction, and extrude devolatilize to obtain (meth)acrylic resin A;

[0027] The general formula (5) is:

[0028]

[0029] The general formula (6) is:

[0030]

[0031] R1 and R2 are each independently selected from hydrogen or straight-chain or branched alkyl groups having 1 to 4 carbon atoms, preferably R1 is a hydrogen atom and R2 is a methyl group; R3 is selected from straight-chain or branched alkyl groups having 1 to 10 carbon atoms, preferably straight-chain or branched alkyl groups having 1 to 3 carbon atoms, and more preferably methyl or ethyl.

[0032] S2, Amination reaction: After heating and melting the (meth)acrylic resin A obtained in S1, add the amination reagent shown in general formula (7) into the melt to carry out the amination reaction;

[0033] S3, Extrusion devolatilization: The product from step S2 is extruded and devolatilized.

[0034] As a preferred embodiment, in S2 of the present invention, the pressure of the amination reaction is 0.5 MPa to 10 MPa, preferably 1 MPa to 8 MPa, and more preferably 3 MPa to 6 MPa. When the amination reaction pressure is too low, the amination reagent exists in a gaseous form at high temperature, making interfacial mixing between the high-viscosity (meth)acrylic resin A and the gaseous amination reagent difficult, resulting in a slow reaction and low conversion rate. When the amination reaction pressure is too high, the pressure of the amination reagent exceeds the melt strength of the (meth)acrylic resin A, causing the sealing ring formed in the extruder to rupture. The amination reagent is prematurely removed through the melt sealing ring, reducing the content of the amination reagent in the reaction system and resulting in a low apparent conversion rate. Furthermore, excessively high reaction pressure causes reaction products (such as water, methanol, ethanol, etc.) to dissolve in the (meth)acrylic resin A, making them difficult to remove during the devolatilization stage, resulting in a high volatile content in the product resin, which is detrimental to the subsequent processing and application of the resin.

[0035] Other additives described in this invention include, but are not limited to, release agents, antioxidants, ultraviolet absorbers, colorants, antistatic agents, flame retardants, reinforcing agents, fillers, and other resin additives known in the art. The types and amounts of these additives are well known to those skilled in the art.

[0036] The general formula (7) of this invention is:

[0037] NH2-R4

[0038] R4 is selected from hydrogen atoms, branched or unbranched alkyl or cycloalkyl groups with 1 to 12 carbon atoms, preferably hydrogen atoms, straight alkyl groups with 1 to 3 carbon atoms, or branched cycloalkane groups with 3 to 12 carbon atoms, and more preferably hydrogen atoms, methyl, ethyl, propyl, or cyclohexyl.

[0039] As a preferred embodiment, the amination reagent of the present invention includes one or more primary amines such as ammonia, monomethylamine, ethylamine, propylamine, and cyclohexylamine, preferably one or more of ammonia, monomethylamine, and cyclohexylamine.

[0040] As a preferred embodiment, in S2 of the present invention, the amount of amination reagent used is 0.1 to 20 parts by weight, preferably 2 to 10 parts by weight, relative to 100 parts by weight of (meth)acrylic resin A.

[0041] When the amount of amination reagent added is too small, (meth)acrylic resin A is not sufficiently chemically modified, and the content of structural units shown in general formulas (3) and (4) in the resin molecular structure is too low. Moreover, when the amount of amination reagent added is too small, the autocatalytic effect of the amination reagent cannot be generated, and the amidation rate is significantly higher than the imideation rate, which is not conducive to improving the heat resistance of the resin. When the amount of amination reagent added is too large, the autocatalytic effect of the amination reagent tends to catalyze the degradation of the structure shown in general formula (3) and generate the structure shown in general formula (4), which in turn leads to increased brittleness, decreased mechanical strength, and significantly higher yellowness value of the (meth)acrylic resin.

[0042] As a preferred embodiment, the initiator of the present invention includes one or more of azobisisobutyronitrile, azobisisoheptanenitrile, dimethyl azobisisobutyrate, azodicarbonamide, benzoyl peroxide, dibenzoyl peroxide, tert-butyl peroxide, tert-butyl peracetate, tert-butyl peroxide isobutyrate, tert-butyl peroxide-2-ethylhexanoate, tert-butyl peroxide-3,5,5-trimethylhexanoate, and 1,1-bis-(tert-butylperoxide)-3,3,5-trimethylcyclohexane, preferably one or two of azobisisobutyronitrile and tert-butyl peroxide-3,5,5-trimethylhexanoate.

[0043] As a preferred option, the amount of initiator added is 0.001 to 0.05 parts by mass per 100 parts by mass of monomer (total amount of monomers of general formula (1)-(2)), preferably 0.005 to 0.02 parts by mass.

[0044] As a preferred embodiment, the chain transfer agent of the present invention includes one or more of 2-mercaptoethanol, n-butanethiol, tert-butanethiol, n-octanethiol, isooctanethiol, n-dodecylthiol, tert-dodecylthiol, mercaptoacetic acid, and isooctyl 3-mercaptopropionate, preferably one or more of 2-mercaptoethanol, n-octanethiol, and tert-dodecylthiol.

[0045] As a preferred option, the amount of chain transfer agent added is 0.05-0.5 parts by mass per 100 parts by mass of monomer (total amount of monomers of general formula (1)-(2)), preferably 0.1-0.3 parts by mass.

[0046] In S2 of the present invention, a blend comprising an amination-modified (meth)acrylic resin (i.e., imide resin B), an unmodified (meth)acrylic resin (i.e., (meth)acrylic resin A), and an unreacted amination reagent is obtained.

[0047] The polymerization method of the present invention can be any one of bulk polymerization, solution polymerization, suspension polymerization or emulsion polymerization, with bulk polymerization being preferred.

[0048] Regarding the temperature during the polymerization reaction, it can be appropriately set based on the polymerization method or requirements such as polymerization rate, viscosity of the polymerization solution, and suppression of by-product formation. In free radical polymerization, the polymerization temperature is preferably 80–160°C, more preferably 90–140°C, during bulk polymerization.

[0049] In S1 of this invention, the polymerization reaction vessel can be selected from a fully mixed-flow high-pressure reactor, and the outlet conversion rate of the fully mixed-flow reactor is controlled to be 50% to 70%. When the outlet conversion rate is too low, it is not economical to produce; when the outlet conversion rate is too high, the viscosity of the material inside the reactor is too high, which is not conducive to mass and heat transfer.

[0050] In this invention, the devolatilization stage S1 is used to remove unreacted monomers and / or solvents; the devolatilization stage S3 is used to remove unreacted amination reagents and / or byproducts.

[0051] In a specific embodiment, in S1 or S2, during the devolatilization stage, the temperature at the devolatilization port is controlled at 230-300℃, the vacuum degree is -0.098MPa to -0.07MPa, and the devolatilization time does not exceed 60min, such as 5min, 10min, 15min, 20min, 30min, 40min, or 50min.

[0052] When the devolatilization temperature is too low, the volatile matter is not completely removed; when the devolatilization temperature is too high, the polymer is prone to yellowing due to heat. Those skilled in the art can make appropriate adjustments to the devolatilization temperature and other conditions.

[0053] In this invention, the (meth)acrylic resin A undergoing the amination reaction exists entirely in melt form in the reactor. This eliminates the adverse effects of the polymer solvent on the amination reaction and increases the reaction rate between the (meth)acrylic resin molecules and the amination reagent.

[0054] In S2 of the present invention, the temperature at which the (meth)acrylic resin A undergoes the amination reaction with the amination reagent is 220°C to 280°C, preferably 240°C to 260°C.

[0055] As a preferred embodiment, in S2 of this invention, the amination reaction vessel can be selected from a single-screw extruder, a twin-screw extruder, a fully mixed-flow autoclave, etc., with a twin-screw extruder being preferred. When a twin-screw extruder is selected as the reaction vessel, the screw speed of the extruder is controlled at 80-200 rpm, and the temperature of the amination reaction in the extruder is 220℃-280℃, preferably 240℃-260℃. According to the study of amination reaction kinetics, when the reaction temperature is too low, the amination reaction rate is slow and the reaction degree is low, which is not conducive to the heat resistance modification of (meth)acrylic resins; when the reaction temperature is too high, the amination reaction occurs violently, and imide structures are easily formed between molecular chains, resulting in a large amount of insoluble gel in the resin, and the resin product is unqualified. In addition, due to the properties of (meth)acrylic resins themselves, too low or too high reaction temperatures will cause the resin to fail to melt or degrade at high temperatures.

[0056] The present invention also provides an optical grade resin molded article, specifically an injection molded part for automotive lamps and an optical film, wherein the injection molded part for automotive lamps and the optical film use the above-mentioned acrylic resin composition as raw materials.

[0057] The acrylic resin composition of this invention possesses excellent properties, including high transparency, high heat resistance, and high resistance to humid and hot environments. Using (meth)acrylic resin A, which has good heat resistance, as the modifying raw material, the resin is amination modified with the amination reagent of this invention. While maintaining the content of cyclic rigid heat-resistant groups in the polymer chain essentially unchanged, the (meth)acrylic acid and glutaric anhydride structural units are converted into (meth)acrylamide and glutarimide structural units, significantly reducing the proportion of polar groups in the polymer, thereby improving the resin's resistance to humid and hot environments. Furthermore, by using (meth)acrylic resin instead of ordinary PMMA resin as the modifying raw material, and employing an amide reaction with lower activation energy and easier reaction instead of an amino ester exchange reaction, the energy consumption during the modification process is reduced, and the reaction conversion rate is improved. The technology provided by this patent has good prospects for cost reduction, efficiency improvement, environmental protection, and energy conservation in future industrial continuous production. Detailed Implementation

[0058] The embodiments of the present invention will be further described below with reference to examples. However, the present invention is not limited to the listed embodiments, but should also include any other known modifications within the scope of the claims of the present invention.

[0059] The sources of raw materials involved in the embodiments are shown in Table 1:

[0060] Table 1. Raw material information involved in the embodiments.

[0061]

[0062] Unless otherwise specified, all other ingredients are commercially available products.

[0063] The following are the methods for testing the structure and properties of polymers:

[0064] Conversion rate test: The conversion rate is calculated based on the ratio of the mass of the dried polymer after devolatilization to the feed amount of the reaction solution.

[0065] Imidi and amidation rate tests: The resin was subjected to 1H-NMR analysis using a BRUKER AvanceIII (400MHz) instrument to determine the content (mol%) of each monomer unit in the resin, namely glutarimide (3.06ppm), (meth)acrylamide (2.68ppm), and (meth)acrylate (3.60ppm). The molar content (mol%) was then converted to mass content (wt%) using the molecular weight of each monomer unit.

[0066] Acid value test: Dissolve 0.3 g of the obtained acrylic resin composition in a mixed solvent of 37.5 ml dichloromethane and 37.5 ml methanol. After adding 2 drops of phenolphthalein ethanol solution, add 5 ml of 0.1 N potassium hydroxide aqueous solution. Titrate the excess alkali with 0.1 N hydrochloric acid, and calculate the acid value using the difference in milliequivalents between the added alkali and the hydrochloric acid used to achieve neutralization. The molar content of carboxyl structural units in the polymer can be calculated using the following formula: n = [x / (540-99x / 100)] × 100%; where n is the molar content (%) and x is the test acid value (mgKOH / g).

[0067] Molecular weight determination: Molecular weight was determined using gel permeation chromatography (GPC) with a Water 996 instrument. The mobile phase was tetrahydrofuran (THF), and the detector was a parallax refractive index detector. Five chromatographic columns, each 7.8 × 300 mm in size, were used; monodisperse PMMA was used as the standard.

[0068] Glass transition temperature test: Referring to standard GBT 19466.2-2004, the glass transition temperature of the resin was tested using a differential scanning calorimeter at a heating / cooling rate of 10℃ / min.

[0069] Heat distortion temperature test: Referring to standard ISO 75-2-2013, the obtained acrylic resin was dried at 80℃ for 4 hours, and then injection molded at 230℃ using an injection molding machine. The sample dimensions were controlled as follows: length L (80±1.0) mm; width B (10±0.2) mm; thickness H (4±0.2) mm. The heat distortion temperature of the resin was tested using a Vicat heat distortion temperature tester.

[0070] Humidity and heat resistance test: The injection-molded sample was placed at 60℃ and 95% relative humidity for one week. The change rate of sample size after placement was calculated using the following formula, where L refers to the length of the sample under the corresponding conditions: Deformation rate % = (L 放置后 —L 放置前 ) / L 放置前 ×100%

[0071] Transmittance and yellowness value testing: The injection-molded samples were placed at 60℃ and 95% relative humidity for one week. The optical properties, such as total light transmittance and yellowness value YI, could be measured using a colorimeter. Instrument model: Hunterlab VIS; Test standards: transmittance ISO 13148-1-2019, yellowness value: GB / T-38922-2021.

[0072] Moisture permeability test: The resin composition is processed into a 40um film by casting. Then, the amount of water vapor (mass) passing through a unit area of ​​the acrylic resin film in 24 hours is tested using a moisture permeability test box. This is the moisture permeability.

[0073]

Manufacturing Example 1

[0074] The mixing tank and reactor used for polymerization are heated to 120°C, and at the same time, vacuuming and nitrogen purging are performed to fully replace and remove impurities such as water and oxygen contained in the mixing tank and reactor.

[0075] Add methyl methacrylate (94% of the total monomer molars), methacrylic acid (6% of the total monomer molars), 0.012 parts by mass of tert-butyl peroxide-3,5,5-trimethylhexanoate, and 0.27 parts by mass of tert-dodecyl mercaptan (based on 100 parts by mass of monomer) to a mixing tank and mix thoroughly to prepare the reaction solution.

[0076] The reaction solution after batching was continuously added to the fully mixed flow reactor (effective volume 10L) at a flow rate of 1.5KG / h, and the reactor temperature was controlled at 140℃ with an average residence time of 2h.

[0077] The slurry obtained from the above reaction is continuously fed into a devolatilization twin-screw extruder to remove unreacted monomers and other volatile components under conditions of vacuum of -0.095 MPa, temperature of 230°C, and residence time of 10 min. The devolatilized material is then crushed by a pulverizer to obtain (meth)acrylic resin A1.

[0078]

Manufacturing Example 2

[0079] The mixing tank and reactor used for polymerization are heated to 120°C, and at the same time, vacuuming and nitrogen purging are performed to fully replace and remove impurities such as water and oxygen contained in the mixing tank and reactor.

[0080] Add methyl methacrylate (90% of the total monomer molars), methacrylic acid (10% of the total monomer molars), 0.010 parts by mass of azobisisobutyronitrile, and 0.19 parts by mass of n-octyl mercaptan (based on 100 parts by mass of monomer) to the mixing tank and mix thoroughly to prepare the reaction solution.

[0081] The reaction solution after batching was continuously added to the fully mixed flow reactor (effective volume 10L) at a flow rate of 1.5KG / h, and the temperature inside the reactor was controlled at 85℃ with an average residence time of 2.5h.

[0082] The slurry obtained from the above reaction is continuously fed into a devolatilization twin-screw extruder to remove unreacted monomers and other volatile components under conditions of vacuum of -0.095 MPa, temperature of 230°C, and residence time of 10 min. The devolatilized material is then crushed by a pulverizer to obtain (meth)acrylic resin A2.

[0083]

Manufacturing Example 3

[0084] The mixing tank and reactor used for polymerization are heated to 120°C, and at the same time, vacuuming and nitrogen purging are performed to fully replace and remove impurities such as water and oxygen contained in the mixing tank and reactor.

[0085] Add methyl methacrylate (98% of the total monomer molars), methacrylic acid (2% of the total monomer molars), 0.015 parts by weight of tert-butyl peroxide-3,5,5-trimethylhexanoate, and 0.255 parts by weight of tert-dodecyl mercaptan (based on 100 parts by weight of monomer) to a mixing tank and mix thoroughly to prepare a reaction solution.

[0086] The reaction solution after batching was continuously added to a fully mixed flow reactor (effective volume 10L) at a flow rate of 1.5KG / h, and the reactor temperature was controlled at 135℃ with an average residence time of 1.8h.

[0087] The slurry obtained from the above reaction is continuously fed into a devolatilization twin-screw extruder to remove unreacted monomers and other volatile components under conditions of vacuum of -0.095 MPa, temperature of 230°C, and residence time of 10 min. The devolatilized material is then crushed by a pulverizer to obtain (meth)acrylic resin A3.

[0088] [Manufacturing Example 4 - Comparative Example]

[0089] The mixing tank and reactor used for polymerization are heated to 120°C, and at the same time, vacuuming and nitrogen purging are performed to fully replace and remove impurities such as water and oxygen contained in the mixing tank and reactor.

[0090] Add methyl methacrylate in a quantity equal to 100% of the total monomer moles to a mixing tank, without adding other monomers, along with 0.012 parts by weight of tert-butyl peroxide-3,5,5-trimethylhexanoate and 0.27 parts by weight of tert-dodecyl mercaptan (based on 100 parts by weight of monomers), and mix thoroughly to prepare the reaction solution.

[0091] The reaction solution after batching was continuously added to the fully mixed flow reactor (effective volume 10L) at a flow rate of 1.5KG / h, and the reactor temperature was controlled at 140℃ with an average residence time of 2h.

[0092] The slurry obtained from the above reaction is continuously fed into a devolatilization twin-screw extruder to remove unreacted monomers and other volatile components under conditions of vacuum of -0.095 MPa, temperature of 230°C, and residence time of 10 min. The devolatilized material is then crushed by a pulverizer to obtain (meth)acrylic resin A4.

[0093] [Manufacturing Example 5 - Comparative Example]

[0094] The mixing tank and reactor used for polymerization are heated to 120°C, and at the same time, vacuuming and nitrogen purging are performed to fully replace and remove impurities such as water and oxygen contained in the mixing tank and reactor.

[0095] Add methyl methacrylate (80% of the total monomer molars), methacrylic acid (20% of the total monomer molars), 0.012 parts by weight of tert-butyl peroxide-3,5,5-trimethylhexanoate, and 0.27 parts by weight of tert-dodecyl mercaptan (based on 100 parts by weight of monomer) to a mixing tank and mix thoroughly to prepare a reaction solution.

[0096] The reaction solution after batching was continuously added to the fully mixed flow reactor (effective volume 10L) at a flow rate of 1.5KG / h, and the reactor temperature was controlled at 140℃ with an average residence time of 2h.

[0097] The slurry obtained from the above reaction is continuously fed into a devolatilization twin-screw extruder to remove unreacted monomers and other volatile components under conditions of vacuum of -0.095 MPa, temperature of 230°C, and residence time of 10 min. The devolatilized material is then crushed by a pulverizer to obtain (meth)acrylic resin A5.

[0098] Table 2. Monomer feed ratios and resin A characterization results used in the manufacturing examples.

[0099]

[0100]

Example 1

[0101] The barrel temperatures of the plasticizing, reaction, and devolatilization sections of a co-rotating twin-screw extruder with a screw diameter of 26 mm and an aspect ratio of 56 were set to 145℃, 240℃, and 240℃, respectively, while the screw speed was controlled at 160 rpm. 100 parts by weight of (meth)acrylic resin A1 were added to the extruder feed port at a rate of 4 kg / h. After the resin was heated and melted, 3 parts by weight of methylamine were injected into the melt as an amination agent through a plunger pump and injection gun at a rate of 2 g / min and an injection pressure of 3.4 MPa. The reaction residence time was approximately 20 seconds. The vacuum degree at the extruder devolatilization port was set to -0.095 MPa to fully remove the volatile organic compounds from the resin. After filtering through a 200-mesh metal filter, the resin was extruded through a round die and pelletized into pellets to obtain a composition of (meth)acrylic resin and imide resin.

[0102]

Example 2

[0103] The amination reagent was changed to ammonia, and other experimental conditions and operations were the same as in Example 1.

[0104]

Example 3

[0105] The amination reagent was changed to cyclohexylamine, the injection amount of the amination reagent was 10 parts by mass, the injection speed of the spray gun was changed to 6.67 g / min, the injection pressure was 4.2 MPa, and other experimental conditions and operations were the same as in Example 1.

[0106]

Example 4

[0107] The barrel temperatures of the plasticizing section, reaction section, and devolatilization section of the co-rotating twin-screw extruder were set to 140℃, 260℃, and 260℃, respectively. The type of (meth)acrylic resin was changed to A2, the amount of amination reagent injected was 10 parts by mass, the injection speed of the amination reagent spray gun was changed to 6.67 g / min, and the injection pressure was 6.0 MPa. Other experimental conditions and operations were the same as in Example 1.

[0108]

Example 5

[0109] The type of (meth)acrylic resin was changed to A2, and other experimental conditions and operations were the same as in Example 3.

[0110]

Example 6

[0111] The type of (meth)acrylic resin was changed to A3, and other experimental conditions and operations were the same as in Example 4.

[0112]

Example 7

[0113] The amount of amination reagent injected was 10 parts by mass, the injection speed of the spray gun was changed to 6.67 g / min, the injection pressure was 4.2 MPa, and other experimental conditions and operations were the same as in Example 1.

[0114]

Example 8

[0115] The amount of amination reagent injected was 20 parts by mass, and the injection speed of the spray gun was changed to 13.3 g / min. Other experimental conditions and operations were the same as in Example 1.

[0116]

Example 9

[0117] The amount of amination reagent injected was 1 part by mass, and the injection speed of the spray gun was changed to 0.67 g / min. Other experimental conditions and operations were the same as in Example 2.

[0118] Comparative Example 1

[0119] The type of (meth)acrylic resin was changed to A4, and other experimental conditions and operations were the same as in Example 1.

[0120] Comparative Example 2

[0121] The type of (meth)acrylic resin was changed to A5, and other experimental conditions and operations were the same as in Example 1.

[0122] Comparative Example 3

[0123] The amount of amination reagent added was changed to 0, and other experimental conditions and operations were the same as in Example 1.

[0124] Comparative Example 4

[0125] Change the (meth)acrylic resin type to A4, and keep the other experimental conditions and procedures the same as in Comparative Example 3.

[0126] Comparative Example 5

[0127] Change the (meth)acrylic resin type to A5, and keep the other experimental conditions and procedures the same as in Comparative Example 3.

[0128] Comparative Example 6

[0129] 80 parts by weight of (meth)acrylic resin A1 and 20 parts by weight of toluene were mixed and dissolved thoroughly to obtain a homogeneous polymer solution of (meth)acrylic resin A1 and toluene.

[0130] The barrel temperatures of the plasticizing, reaction, and devolatilization sections of a co-rotating twin-screw extruder with a screw diameter of 26 mm and an aspect ratio of 56 were set to 145°C, 240°C, and 240°C, respectively, and the screw speed was controlled at 160 rpm. A polymer solution of 100 parts by weight (based on the mass of (meth)acrylic) resin A1 was added to the extruder feed port at a rate of 4 kg / h. After the polymer solution was heated and melted, 3 parts by weight of methylamine was injected into the melt as an amination agent at a rate of 2 g / min and an injection pressure of 3.4 MPa using a plunger pump and injection gun. The reaction residence time was approximately 20 seconds. The vacuum degree at the extruder devolatilization port was set to -0.095 MPa to fully remove the volatile organic compounds from the resin. After filtering through a 200-mesh metal filter, the resin was extruded through a round die and pelletized into strands using a pelletizer to obtain the (meth)acrylic resin and imide resin composition described in this invention.

[0131] The imidization rate, amidation rate, acid value, glass transition temperature, heat distortion temperature, product deformation rate, light transmittance, yellowing index, and membrane moisture permeability of the products tested in Examples 1 to 7 and Comparative Examples 1 to 6 are shown in Table 3 below.

[0132] Table 3. Characterization results of raw material ratios and resin compositions A & B used in the examples and comparative examples.

[0133]

[0134]

[0135] As shown in the table above, the heat-resistant and moisture-resistant acrylic resin composition provided by this invention has an imidization rate of 31.77%–24.8%, an amidation rate of 0.1%–4.8%, a glass transition temperature of 125.0–135.7℃, a heat distortion temperature of 88.9–97.2℃, a dimensional deformation rate of 1.5%–2.4% after damp heat aging, a light transmittance of 90.7%–91.7%, a yellowness index (YI, 3mm) of 1.42–2.13, and a moisture permeability of 131–165 g / m² for a 40 μm thick film. 2 ·day.

[0136] Further analysis of Examples 1 and 1, and Examples 3 and 5 reveals that adding (meth)acrylic acid comonomers to (meth)acrylic acid resin A and increasing the carboxyl content in the base resin A can significantly improve the amide reaction rate between the amination reagent (methylamine) and the resin, increase the glass transition temperature of the resin composition, reduce the deformation rate and water vapor transmission rate of the product under humid and hot conditions, and improve the heat resistance and humid and hot resistance of the product. This demonstrates that introducing an imide structure into the polymer backbone, with its strong conjugated structure and rigid ring system, can significantly restrict the free movement of polymer chain segments, thereby increasing the glass transition temperature (Tg) of the polymer. Furthermore, replacing the highly polar carboxylic acid structure and glutaric anhydride structure with an imide structure exhibiting weak polarity and high density helps reduce the penetration path and diffusion rate of moisture in the material, thus effectively improving the material's barrier properties.

[0137] Analysis of Example 1 and Comparative Example 2 shows that when the carboxyl group content in resin A is too high, its effect on improving the conversion rate of the amide reaction is no longer significant. Furthermore, while increasing the carboxyl group content helps to raise the glass transition temperature, it is detrimental to the dimensional stability of the resin product in humid and hot environments and the water vapor barrier properties of the membrane, greatly reducing the environmental tolerance of the product. Therefore, the content of carboxylic acid groups is not without upper limits; its dosage must be precisely controlled within a reasonable range to achieve a comprehensive balance between heat resistance, humid heat resistance, and membrane barrier properties.

[0138] Analysis of Examples 1, 2, 5, and 6 shows that amination agents such as methylamine, ammonia, and cyclohexylamine can all improve the heat resistance of the base resin A. Among them, the heat resistance improvement effect of ammonia is comparable to that of methylamine, but the optical transmittance and dimensional stability of its product are slightly lower than those of methylamine. Cyclohexylamine has the best heat resistance improvement effect, but its reactivity is lower than that of methylamine and ammonia, resulting in a slightly higher acid value (i.e., carboxyl content) in the resin composition, and its dimensional stability and water vapor barrier properties are only comparable to those modified by methylamine and ammonia.

[0139] Analysis of Examples 1 and 7 shows that increasing the proportion of the amination reagent can further improve the imidization rate and amidation rate of the resin composition, and reduce the acid value of the composition. This results in improved composition properties: increased glass transition temperature and heat distortion temperature, while the deformation rate, transmittance, and yellowness value remain essentially unchanged, and the moisture permeability decreases significantly. Therefore, increasing the proportion of the amination reagent is also one of the efficient methods to improve the heat resistance and damp heat resistance of the resin composition.

[0140] Analysis of Example 1 and Comparative Example 6 shows that amination reactions can also be carried out using polymer solutions of (meth)acrylic resins as reactants, but the reaction conversion rate is much lower than that of resin melts. Even after sufficient removal of volatiles in the extruder, the deformation rate, yellowness value, and moisture permeability of the resin composition deteriorated to varying degrees compared to Example 1. Therefore, this application emphasizes that using resin melts for amination reactions can greatly improve reaction efficiency. Although the technical route of amination reactions using resin solutions is feasible, it is not valuable for large-scale scaling and industrial production due to its low reaction efficiency.

[0141] Furthermore, during the injection molding and casting processes of the resins in the above examples and comparative examples, Comparative Examples 2 and 5 showed a large number of bubble marks and bubble spots on the surface of the products. The surface integrity of the 40µm cast films obtained from all resin compositions was evaluated, where “○” indicates fewer than 5 bubble marks or fewer than 2 bubble spots per square meter of film, “△” indicates 5 to 10 bubble marks or 2 to 4 bubble spots per square meter of film, “□” indicates 11 to 25 bubble marks or 5 to 10 bubble spots per square meter of film, and “◇” indicates more than 25 bubble marks or more than 10 bubble spots per square meter of film. The surface integrity results of the films prepared from the resin compositions of Examples 1 to 7 and Comparative Examples 1 to 6 are shown in Table 4.

[0142] Table 4. Evaluation of the surface integrity of the resin compositions processed into films in the examples and comparative examples.

[0143]

[0144] Therefore, it is evident that resins that have not undergone amination modification, or resins with excessively high acid values ​​(i.e., containing too many carboxyl units in their molecular structure), will have an adverse effect on the processing and molding properties of the resin. After the amination reaction converts carboxylic acid and anhydride groups into amide and imide groups, the thermal degradation reaction of the resin composition is inhibited by the imide groups. The high-temperature processing properties of the resin are significantly optimized compared to resins without imide modification or high-acid-value resins, thus meeting the application requirements of high-purity and high-flatness optical-grade products.

Claims

1. An acrylic resin composition comprising (meth)acrylic resin A and imide resin B; wherein (meth)acrylic resin A comprises repeating units shown in general formula (1) and general formula (2), and imide resin B comprises repeating units shown in general formula (1), general formula (2), general formula (3), and general formula (4). The general formula (1) is: The general formula (2) is: The general formula (3) is: The general formula (4) is: in, R1 and R2 are each independently selected from hydrogen or straight-chain or branched alkyl groups having 1 to 4 carbon atoms, preferably R1 is a hydrogen atom and R2 is a methyl group; R3 is selected from straight-chain or branched alkyl groups having 1 to 10 carbon atoms, preferably straight-chain or branched alkyl groups having 1 to 3 carbon atoms, more preferably methyl or ethyl; R4 is selected from hydrogen, branched or unbranched alkyl groups having 1 to 12 carbon atoms, or cycloalkyl groups, preferably hydrogen, straight-chain alkyl groups having 1 to 3 carbon atoms, or branched cycloalkane groups having 3 to 12 carbon atoms, more preferably hydrogen, methyl, ethyl, propyl, or cyclohexyl.

2. The acrylic resin composition according to claim 1, characterized in that, The acrylic resin composition comprises (meth)acrylic resin A with a glass transition temperature greater than or equal to 124°C and imide resin B with a glass transition temperature greater than or equal to 125°C.

3. The acrylic resin composition according to claim 1 or 2, characterized in that, The acrylic resin composition contains (meth)acrylic resin A in a mass ratio of 5% wt to 80% wt, and imide resin B in a mass ratio of 20% wt to 95% wt.

4. The acrylic resin composition according to any one of claims 1-3, characterized in that, In the (meth)acrylic resin A, the molar percentage of repeating units represented by general formula (1) is 90% to 98%, and the molar percentage of repeating units represented by general formula (2) is 2% to 10%, based on the molar amounts of repeating units in general formula (1) and general formula (2).

5. The acrylic resin composition according to any one of claims 1-4, characterized in that, In the imide resin B, the molar percentage of repeating units represented by general formula (1) is 65% to 98%, the molar percentage of repeating units represented by general formula (2) is 0% to 5%, the molar percentage of repeating units represented by general formula (3) is 0.99% to 25%, and the molar percentage of repeating units represented by general formula (4) is 0.01% to 5%, based on the molar amounts of repeating units in general formulas (1), (2), (3), and (4).

6. A method for preparing the acrylic resin composition according to any one of claims 1-5, comprising the following steps: S1. Polymer preparation: Mix monomers, initiators and / or chain transfer agents, and optional other additives as shown in general formula (5) and general formula (6), carry out polymerization reaction, and extrude devolatilize to obtain (meth)acrylic resin A; The general formula (5) is: The general formula (6) is: R1 and R2 are each independently selected from hydrogen or straight-chain or branched alkyl groups having 1 to 4 carbon atoms, preferably R1 is a hydrogen atom and R2 is a methyl group; R3 is selected from straight-chain or branched alkyl groups having 1 to 10 carbon atoms, preferably straight-chain or branched alkyl groups having 1 to 3 carbon atoms, and more preferably methyl or ethyl. S2, Amination reaction: After heating and melting the (meth)acrylic resin A obtained in S1, add the amination reagent shown in general formula (7) into the melt to carry out the amination reaction; S3, Extrusion devolatilization: The product from step S2 is subjected to extrusion devolatilization; The general formula (7) is: NH2-R4 R4 is selected from hydrogen atoms, branched or unbranched alkyl or cycloalkyl groups with 1 to 12 carbon atoms, preferably hydrogen atoms, straight alkyl groups with 1 to 3 carbon atoms, or branched cycloalkane groups with 3 to 12 carbon atoms, and more preferably hydrogen atoms, methyl, ethyl, propyl, or cyclohexyl.

7. The method according to claim 6, characterized in that, The amination reagent includes one or more of ammonia, monomethylamine, ethylamine, propylamine, and cyclohexylamine.

8. The method according to claim 6 or 7, characterized in that, In S2, the amount of amination reagent used is 0.1 to 20 parts by weight, preferably 2 to 10 parts by weight, relative to 100 parts by weight of (meth)acrylic resin A.

9. The method according to any one of claims 6-8, characterized in that, The pressure of the amination reaction is 0.5 MPa to 10 MPa, preferably 1 MPa to 8 MPa, more preferably 3 MPa to 6 MPa; and / or the temperature of the amination reaction is 220°C to 280°C, preferably 240°C to 260°C.

10. An optical grade resin molded article, including an injection molded part for automotive lamps and / or an optical film.

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