Narrow-distribution high-light-transmittance MS resin and preparation method thereof

Abstract

The invention belongs to the technical field of high polymer material preparation, and particularly discloses narrow-distribution high-light-transmittance MS resin and a preparation method thereof. The preparation method specifically comprises the following steps: (1) conveying 25-65 parts by mass of methyl methacrylate (MMA), 25-65 parts by mass of styrene (ST) and 5-15 parts by mass of ethylbenzene (EB) into a mixing kettle, and uniformly mixing; (2) continuously conveying the mixed solution of methyl methacrylate, styrene and ethylbenzene into a plug flow reaction kettle according to a certain flow, initiating polymerization reaction through an initiator, and adding a chain transfer agent to adjust the polymerization molecular weight; and (3) carrying out two-stage devolatilization extrusion treatment to obtain the high-light-transmittance MS resin. The prepared MS resin has the following properties that the haze is smaller than or equal to 1.2%, and the light transmittance is larger than or equal to 92.5%.

Description

Technical Field

[0001] This invention belongs to the field of polymer material preparation technology, and specifically discloses a narrow-distribution high-transmittance MS resin and its preparation method. Background Technology

[0002] MS resin is a copolymer of styrene and methyl methacrylate (MMA). It possesses excellent processing flowability, low moisture absorption, weather resistance, and superior optical properties. As a transparent, non-toxic thermoplastic, it has wide applications in optical displays, daily necessities, and medical fields. In recent years, with the significant trend towards larger TV panel sizes, MS products have stood out among other materials due to their low water absorption and swelling rate, light weight, and lower cost compared to PMMA, making them widely used in LCD and LED liquid crystal displays. MS is a special grade of PMMA, offering similar optical properties to PMMA but with lower moisture absorption, avoiding warping issues in thinner sheets. The processing of MS diffuser plates and light guide plates can enhance added value and provide complementary supplies to the liquid crystal display industry.

[0003] Existing technologies mostly employ single-reactor or two-reactor polymerization, making it difficult to achieve precise molecular weight control. The resulting MS resins suffer from problems such as wide molecular weight distribution (PDI>3.5), large fluctuations in transmittance (85-90%), and poor batch stability.

[0004] Therefore, it is necessary to develop a narrow-distribution, high-transmittance MS resin and its preparation method to overcome the above technical problems. Summary of the Invention

[0005] The present invention aims to provide a narrow-distribution, high-transmittance MS resin by selecting appropriate raw materials and coordinating process control factors such as feed rate, temperature, stirring speed, initiator addition ratio, chain transfer agent addition ratio, devolatilization temperature, and pressure.

[0006] The technical solution adopted in this invention is as follows:

[0007] In a first aspect, the present invention provides a method for preparing narrow-distribution high-transmittance MS resin, which adopts a four-reactor series plug flow reactor process, and the reaction process is continuous feeding and discharging; each of the four reactors in series is divided into three independent temperature zones, and each reactor is equipped with an additive injection point;

[0008] The raw materials comprise the following components by weight: methyl methacrylate (MMA) 25-65 parts by weight, styrene (ST) 25-65 parts by weight, and ethylbenzene (EB) 5-15 parts by weight;

[0009] Specifically, the steps include the following:

[0010] After the raw materials of the specified mass ratio are thoroughly mixed, they are continuously and constantly fed into a four-vessel series plug flow reactor using a mixture feed pump. The four reactors have the same volume, and the rate control of the mixture feed pump ensures that the residence time of the mixture in each reactor is 1-2 hours. The temperature settings for the four reactors connected in series are as follows: first reactor: 90-115℃; second reactor: 110-130℃; third reactor: 120-140℃; fourth reactor: 130-165℃. The stirring speeds of the four reactors are as follows: first reactor: 80±5 rpm / min; second reactor: 60±5 rpm / min; third reactor: 45±5 rpm / min; fourth reactor: 30±5 rpm / min.

[0011] The initiator is introduced into the first reactor along with the conveyed mixture through an introduction and injection point set on the feed inlet pipeline of the first reactor; the initiator used is one or both of 1,1-di(tert-butylperoxy)cyclohexane or di-tert-butyl peroxide, and the amount of initiator used is 50-500 ppm of the total mass of the raw materials; the initiator is prepared as a 0.6-1.2 wt% ethylbenzene solution;

[0012] The chain transfer agent is added through inlets set on the inlet pipelines of the first, second, and third reactors respectively; the total amount of chain transfer agent used at the three points is 200-5000 ppm of the total mass of the raw materials; the chain transfer agent and ethylbenzene are mixed to form a homogeneous mixture, and the concentration of the chain transfer agent ethylbenzene solution in the first reactor is 0.5-1.80 wt%;

[0013] Preferably, the concentrations of the chain transfer agent ethylbenzene solution in the second and third reactors are 1.5 to 2.5 times and 4 to 6 times the concentration of the chain transfer agent ethylbenzene solution in the first reactor, respectively.

[0014] Preferably, the amount of ethylbenzene solution added to the second and third reactors is 1.5 to 2.5 times and 2 to 3.5 times the amount of ethylbenzene solution added to the first reactor, respectively.

[0015] Preferably, the initiator is a composite initiation system of 1,1-di(tert-butylperoxy)cyclohexane and di-tert-butyl peroxide, with a mass mixing ratio of 1:0.25-0.50.

[0016] Furthermore, the mass ratio of 1,1-di(tert-butylperoxy)cyclohexane to di-tert-butyl peroxide is 1:0.33.

[0017] Preferably, n-dodecyl mercaptan is used as the chain transfer agent, and the total amount of chain transfer agent used is 200 to 2000 ppm of the total mass of the monomer.

[0018] Preferably, the temperatures of the three zones in each of the four reactors are as follows:

[0019] Temperature settings for zones 1-3 of the first reactor: 109.1 / 109.7.3 / 110.4℃

[0020] Temperature settings for zones 4-6 of the second reactor: 122.5 / 125.3 / 127.2℃

[0021] Temperature settings for zones 7-9 of the third reactor: 130.2 / 132.4 / 135.1℃

[0022] Temperature settings for zones 10-12 of the fourth reactor: 152 / 160 / 154℃.

[0023] Preferably, the volume of the reaction vessel is 5 to 8 liters.

[0024] Preferably, the fourth reactor is followed by a devolatilization granulation unit; the devolatilization unit temperature is 190±10℃, and the gauge pressure of the vacuum is -0.092 to -0.098 MPa. A two-stage flat devolatilization unit is used for devolatilization.

[0025] In a second aspect, the present invention provides a narrow-distribution, high-transmittance MS resin, prepared using the method described in the first aspect.

[0026] Thirdly, the present invention provides a modified resin, which is prepared by mixing MS resin and ABS resin as described in the second aspect at a mass ratio of 1:1 to 1:3, adding an antioxidant, and extruding and granulating at 170 to 230°C.

[0027] The beneficial effects achieved by this invention are as follows:

[0028] 1) By designing a four-reactor temperature field and matching it with the initiator, the reaction rate can be precisely controlled.

[0029] 2) Ethylbenzene concentration gradient control effectively eliminates bubble defects.

[0030] 3) The segmented addition technology of chain transfer agents reduces the standard deviation of molecular weight distribution by 40%.

[0031] 4) The innovative system combined with the phased devolatilization process reduces the residual monomer content to <200ppm.

[0032] By employing a four-tandem plug flow reactor, and through process control of raw material ratio, polymerization temperature, stirring speed, polymerization time, additive addition ratio, devolatilization temperature, and pressure, the structure, size, and distribution of molecular weight are effectively controlled, resulting in MS products with a light transmittance ≥92.5%, haze ≤1.2%, and other indicators reaching or even exceeding the performance indicators of imported products. Detailed Implementation

[0033] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the following embodiments.

[0034] It should be noted that the present invention is not limited to the following embodiments. Unless otherwise specified, all methods described are conventional methods. Unless otherwise specified, all raw materials are available from publicly available commercial sources.

[0035] Unless otherwise defined, the technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0036] Examples 1-3

[0037] To better illustrate the product of the present invention and its manufacturing method, specific embodiments 1 to 3 are described below.

[0038] Examples 1-3 employ the following processes:

[0039] After the raw materials are fully mixed according to the mass ratio, they are continuously and constantly fed into four parallel plug flow reactors in series through a mixture feed pump; the four reactors have the same volume, which is 6.5L.

[0040] Mixed liquor feed rate: 3.65 kg / h

[0041] Temperature settings for zones 1-3 of the first reactor: 109.1 / 109.7.3 / 110.4℃

[0042] Temperature settings for zones 4-6 of the second reactor: 122.5 / 125.3 / 127.2℃

[0043] Temperature settings for zones 7-9 of the third reactor: 130.2 / 132.4 / 135.1℃

[0044] Temperature settings for zones 10-12 of the fourth reactor: 152 / 160 / 154℃

[0045] The concentration of the initiator ethylbenzene solution is 0.96 wt%, and the injection rate is 50 g / h.

[0046] The concentration of the ethylbenzene solution used as a chain transfer agent in the first reactor is 0.64 wt%, and the addition rate is 50 g / h.

[0047] The concentration of the ethylbenzene solution used as a chain transfer agent in the second reactor is 1.28 wt%, and the addition rate is 120 g / h.

[0048] The concentration of the ethylbenzene solution used as a chain transfer agent in the third reactor is 3.20 wt%, and the addition rate is 150 g / h.

[0049] Pure ethylbenzene was added to the fourth reactor at a rate of 50 g / h.

[0050] The stirring speeds for the first to fourth reactors are 80, 60, 45, and 30 rpm / min, respectively.

[0051] The temperature of the plate devolatilizer is 190℃, and the vacuum pressure is -0.095MPa (gauge pressure).

[0052] The formulations for Examples 1-3 are as follows:

[0053] Example 1

[0054] Styrene: 29.3 wt%

[0055] Methyl methacrylate: 58.7 wt%

[0056] Ethylbenzene: 12wt%

[0057] Example 2

[0058] Styrene: 44 wt%

[0059] Methyl methacrylate: 44.0 wt%

[0060] Ethylbenzene: 12wt%

[0061] Example 3

[0062] Styrene: 56 wt%

[0063] Methyl methacrylate: 32.0 wt%

[0064] Ethylbenzene: 12wt%

[0065] Example 4

[0066] Except for the initiator, everything else is the same as in Example 2.

[0067] Initiator: A mixed initiator of 1,1-di(tert-butylperoxy)cyclohexane and di-tert-butyl peroxide in a mass ratio of 3:1 was used. The concentration of the mixed initiator ethylbenzene solution was 0.84 wt%, and the addition rate was 50 g / h.

[0068] Example 5

[0069] Except for the chain transfer agent, everything else is the same as in Example 2.

[0070] The chain transfer agent is an α-methyl dimer.

[0071] The concentration of the chain transfer agent ethylbenzene solution in the first reactor is 1.60 wt%, and the addition rate is 65 g / h.

[0072] The concentration of the chain transfer agent ethylbenzene solution in the second reactor is 3.2 wt%, and the addition rate is 120 g / h.

[0073] The concentration of the chain transfer agent ethylbenzene solution in the third reactor is 8.00 wt%, and the addition rate is 135 g / h.

[0074] Comparative Example

[0075] Except for the parameters specifically mentioned below, the comparative examples are the same as those in Example 2.

[0076] Comparative Example 1

[0077] Using thermal initiation

[0078] Temperature settings for zones 1-3 of the first reactor: 115 / 116 / 117℃

[0079] Temperature settings for zones 4-6 of the second reactor: 125 / 127 / 129℃

[0080] Temperature settings for zones 7-9 of the third reactor: 130.2 / 132.4 / 135.1℃

[0081] Temperature settings for zones 10-12 of the fourth reactor: 152 / 160 / 154℃

[0082] Comparative Example 2

[0083] The temperature in each zone of the first to fourth reactors is the same, all set at 110℃.

[0084] The chain transfer agent is added only to the first reactor, and not to the second or third reactor.

[0085] The concentration of the chain transfer agent ethylbenzene solution in the first reactor is 2.92 wt%, and the addition rate is 150 g / h.

[0086] No ethylbenzene is added to the fourth reaction vessel.

[0087] Comparative Example 3

[0088] Di-tert-butyl peroxide was used as the initiator, the concentration of the ethylbenzene initiator solution was 0.78 wt%, and the addition rate was 50 g / h.

[0089] The temperature in each zone of the first to fourth reactors is the same, all set at 130℃.

[0090] The chain transfer agent is added only to the first reactor, and not to the second or third reactor.

[0091] The concentration of the chain transfer agent ethylbenzene solution in the first reactor is 2.44 wt%, and the addition rate is 200 g / h.

[0092] No ethylbenzene is added to the fourth reaction vessel.

[0093] Application examples

[0094] To better verify the effectiveness and practicality of the product of this invention, transparent ABS alloy tests were conducted using samples from Examples 2, 4, Comparative Examples 2, and 3, as well as a commercially available MS resin standard (Chimei PM-600), as the second base material. These samples were co-extruded with the first base material, Huajin ABS8391 resin, to create the test results. The enantiomeric test numbers are: Application Examples 1-5.

[0095] Five test samples were prepared by mixing the above-mentioned MS resins with ABS resin at a mass ratio of 35:65. An equal proportion of antioxidant (a mixture of antioxidants 1076 and 168, with a mass mixing ratio of 1:4, and an addition amount of 0.5% of the total base material mass) was added. After thorough mixing in a high-speed mixer, extrusion tests were conducted using a TDY-30A extruder. The extrusion process parameters were set as follows:

[0096] The temperature settings for zones 1-7 of the extruder are 180℃, 195℃, 210℃, 215℃, 220℃, 220℃, and 210℃, respectively.

[0097] The extruder head temperature is set to 200℃.

[0098] The extruder screw motor frequency is set to 20Hz.

[0099] The feeding motor frequency is set to 8Hz.

[0100] The extruded modified granules were pressed into thin plates of 100×100×1.2mm, and the optical performance test results are shown in Table 2.

[0101] Test Results

[0102] Table 1 Comparison of test results for the examples and comparative products

[0103]

[0104]

[0105] Table 2. Optical performance test results for application examples.

[0106] Test Project Test Standards unit Application Example 1 Application Example 2 Application Example 3 Application Example 4 Application Example 5 Light transmittance GB / T 2410-2008 ％ 87.32 87.69 82.11 83.06 85.14 Haze GB / T 2410-2008 ％ 6.16 4.28 11.24 35.72 10.64

[0107] As can be seen from Table 1, by using the process of this invention, and through segmented temperature control of each reaction zone, along with the selected concentration ratio and addition method of the initiator and chain transfer agent, the molecular weight and distribution can be precisely controlled. While ensuring that the product's light transmittance and haze value meet the standards, the heat resistance of the product can also be effectively improved.

[0108] As can be seen from Table 1, using a composite initiator is more effective in controlling the molecular weight distribution of the product.

[0109] It is easy to see from Table 2 that, when comparing the optical performance of Example 2 (Application Example 1), Example 4 (Application Example 2), Comparative Example 2 (Application Example 3), Comparative Example 3 (Application Example 4), and the purchased standard sample (Application Example 5), Application Examples 1-2 are significantly better than Application Examples 3-5, indicating that the product of the present invention has practicality and superiority in application.

Claims

1. A method for preparing a narrow distribution high light transmittance MS resin, characterized by, The four-cascade flat push-flow reactor process is adopted, and the reaction process is continuous feeding and discharging; each of the four cascaded reactors is divided into three independent temperature zones, and each reactor is provided with an additive filling point; The raw materials include the following components by mass: 25-65 parts by mass of methyl methacrylate (MMA), 25-65 parts by mass of styrene (ST), and 5-15 parts by mass of ethylbenzene (EB). Specifically, the following steps are included: After the raw materials of the mass ratio are fully mixed, they are continuously fed into the four-cascade flat push-flow reactor through a mixing material feeding pump at a constant rate; the four reactors have the same volume, and the rate of the mixing material feeding pump is controlled so that the residence time of the mixing material in each reactor is 1-2 hours; the temperature of the four reactors in sequence is set as follows: the temperature of the first reactor is 90-115℃, the temperature of the second reactor is 110-130℃, the temperature of the third reactor is 120-140℃, and the temperature of the fourth reactor is 130-165℃; the stirring speeds of the four reactors are respectively: 80±5 rpm / min for the first reactor, 60±5 rpm / min for the second reactor, 45±5 rpm / min for the third reactor, and 30±5 rpm / min for the fourth reactor; The initiator is introduced into the first reactor through an introduction filling point provided on the inlet pipeline of the first reactor together with the delivered mixing material; the initiator used is one or both of 1,1-di(tert-butyl peroxy)cyclohexane and di-tert-butyl peroxide, and the amount of the initiator used is 50-500 ppm of the total mass of the raw materials; the initiator is prepared as a 0.6-1.2 wt% ethylbenzene solution; The chain transfer agent is added through the inlet pipelines of the first, second and third reactors; the total amount of the chain transfer agent used is 200-5000 ppm of the total mass of the raw materials; the chain transfer agent is prepared as a uniform mixture with ethylbenzene, and the concentration of the ethylbenzene solution of the chain transfer agent in the first reactor is 0.5-1.80 wt%.

2. The method for preparing narrow-distribution, high-transmittance MS resin according to claim 1, characterized in that, The concentrations of the ethylbenzene solutions of the chain transfer agents in the second and third reactors are respectively 1.5-2.5 times and 4-6 times the concentration of the ethylbenzene solution of the chain transfer agent in the first reactor.

3. The method of claim 1, wherein the MS resin having a narrow distribution and high light transmittance is prepared by adding a monomer to a polymerization initiator, and then adding a polymerization inhibitor to the mixture. The addition amounts of the ethylbenzene solutions of the chain transfer agents in the second and third reactors are respectively 1.5-2.5 times and 2-3.5 times the addition amount of the ethylbenzene solution of the chain transfer agent in the first reactor.

4. The method of claim 1, wherein the MS resin having a narrow distribution and high light transmittance is prepared by adding a monomer to a polymerization initiator, and then adding a polymerization inhibitor to the mixture. The initiator is a composite initiator system of 1,1-di(tert-butyl peroxy)cyclohexane and di-tert-butyl peroxide, and the mass mixing ratio of the two is 1:0.25-0.

50.

5. The method of claim 4, wherein the MS resin having a narrow distribution and high light transmittance is prepared by adding 0.1 to 10 parts by weight of the compound of formula (1) to 100 parts by weight of the MS resin having a narrow distribution and high light transmittance. The mass mixing ratio of 1,1-di(tert-butyl peroxy)cyclohexane and di-tert-butyl peroxide is 1:0.

33.

6. The method for preparing narrow-distribution, high-transmittance MS resin according to claim 1, characterized in that, The total amount of the chain transfer agent used is 200-2000 ppm of the total mass of the monomers.

7. The method for preparing narrow-distribution, high-transmittance MS resin according to claim 1, characterized in that, The temperatures of the three zones of each of the four reactors are respectively: The temperature settings of the first reactor 1-3 zones are 109.1 / 109.7.3 / 110.4℃ The temperature settings of the second reactor 4-6 zones are 122.5 / 125.3 / 127.2℃ The temperature settings of the third reactor 7-9 zones are 130.2 / 132.4 / 135.1℃ The temperature of the fourth reactor 10-12 zone is set at 152 / 160 / 154℃.

8. The method for preparing narrow-distribution, high-transmittance MS resin according to claim 1, characterized in that, The fourth reactor is followed by devolatilization and granulation; the temperature of the devolatilizer is 190±10℃, and the vacuum pressure is -0.092 to -0.098 MPa (gauge pressure).

9. A narrow-distribution high-transmittance MS resin prepared by the method of any one of claims 1-8.

10. A modified resin prepared by mixing the MS resin of claim 9 with an ABS resin in a mass ratio of 1:1 to 1:3, adding 0.1 to 1% of the total mass of the MS resin and the ABS resin of an antioxidant, and extruding and granulating at 170 to 230℃.

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