Preparation method and application of thermoplastic resin modifier

Abstract

The invention discloses a preparation method and application of a thermoplastic resin modifier. According to the invention, a special core-shell structure is designed, an acid functional monomer is added into a shell layer monomer, and carboxylate is formed through neutralization to play a role of an emulsifier, so that the dosage of the emulsifier is greatly reduced, and the yellowing problem during application is improved; and after the shell layer is formed, the core layer is swelled into the shell layer to form a core-shell structure with a more complete structure, so that the modifier has more excellent impact resistance and processability on the premise of excellent optical performance.

Description

Technical Field

[0001] The invention relates to an impact-resistant modifier with a rubber phase, and in particular to a preparation method and application of a thermoplastic resin modifier. Background Art

[0002] PMMA resin, the full name of which is polymethyl methacrylate in Chinese, is commonly known as organic glass or acrylic. It is a very important transparent polymer material in plastics. It has the advantages of high transparency, high gloss and excellent weather resistance. This type of material is widely used in the fields of construction, electronics, automobiles, etc. However, PMMA also has obvious disadvantages. The material is brittle and notch-sensitive, and has low impact strength, which limits the application of the material itself. The commonly used modification method is to add an impact modifier with a rubber phase, such as patent CN113004453B, which provides an emulsion polymerization PMMA toughening agent.

[0003] The powder making processes suitable for PMMA modifiers generated by emulsion polymerization generally include spray drying and coagulation processes. The spray drying process uses steam heating to evaporate the water in the emulsion to obtain the modifier powder, and the coagulation process is to demulsify the emulsion with a flocculant and then centrifuge and dry it. Among them, the former has the advantages of simple process and no industrial wastewater, and has stronger promotion and application. However, the inventors have found through continuous research that the PMMA modifier powder produced by the spray process is easy to cause PMMA to turn yellow in the subsequent mixing process, affecting its optical properties, and it is more difficult to ensure the application effect than the PMMA modifier powder produced by the coagulation process.

[0004] In-depth research has found that the main reason for the above yellowing problem is that the spray process will leave the emulsifier used in the emulsion polymerization method in the modifier powder. In the subsequent PMMA mixing process, the emulsifier decomposes due to heat, causing the PMMA to turn yellow, affecting its optical properties.

[0005] Therefore, based on how to reduce the amount of emulsifier added when preparing the modifier by emulsion polymerization, so as to make it more suitable for powdering by spraying process and ensure the high transparency of PMMA, the present invention proposes a new solution. Summary of the invention

[0006] In order to solve the above technical problems, the present invention proposes a preparation method and application of a thermoplastic resin modifier. The present invention designs a special core-shell structure, first adds an acid functional monomer to the shell monomer, and neutralizes to form a carboxylate to act as an emulsifier, which greatly reduces the amount of emulsifier used and improves the yellowing problem during application; after the shell is formed, the core layer is swelled into the shell to form a more complete core-shell structure, so that the modifier has better impact and processability while having excellent optical properties.

[0007] To achieve the above purpose, the technical solution adopted by the present invention is as follows:

[0008] A method for preparing a thermoplastic resin modifier comprises the following preparation process:

[0009] 1) preparing a shell layer pre-emulsion I and a core layer monomer solution II according to parts by weight;

[0010] Shell pre-emulsion I:

[0011] 500-700 parts of hard monomer, preferably 550-650 parts,

[0012] Soft monomer 10-80 parts, preferably 20-70 parts,

[0013] 120-180 parts of acid functional monomer, preferably 130-170 parts,

[0014] Chain transfer agent 5-11 parts, preferably 6-10 parts,

[0015] Emulsifier 0.5-5 parts, preferably 1-4 parts,

[0016] 120-220 parts of water, preferably 130-200 parts,

[0017] Nuclear layer monomer solution II:

[0018] Soft monomer 600-700 parts, preferably 610-680 parts;

[0019] 100-200 parts of hard monomer, preferably 120-190 parts;

[0020] 0.5-5 parts of cross-linking monomer, preferably 1-3 parts;

[0021] 2) Prepare an initiator solution and divide it into two parts, one as the bottom initiator and the other as the dropwise initiator;

[0022] 3) Using water as the primer, the reactor is heated to 80-90°C; adding the initiator at the bottom of the reactor at one time, mixing evenly, then dropping the shell pre-emulsion I and the initiator to carry out the shell polymerization reaction; after sufficient reaction, dropping the neutralizer and keeping the temperature;

[0023] 4) Cooling the reactor to 40-60°C, adding the core layer monomer solution II dropwise, and then adding the accelerator, oxidant and reductant; cooling and discharging;

[0024] 5) Powdering the emulsion through a spraying process to obtain the modifier.

[0025] In some embodiments, the hard monomer is one or both of styrene and methyl methacrylate;

[0026] Preferably, the soft monomer is one or more of isooctyl acrylate, butyl acrylate, ethyl acrylate, and methyl acrylate;

[0027] Preferably, the acid functional monomer is one or more of acrylic acid and methacrylic acid;

[0028] Preferably, the cross-linking monomer is one or more of ethylene glycol dimethacrylate, butanediol dimethacrylate, and divinylbenzene.

[0029] In some embodiments, the chain transfer agent is one or both of dodecyl mercaptan and n-octyl mercaptan;

[0030] Preferably, the emulsifier is one or both of disodium dodecyl diphenyl ether sulfonate and sodium dodecyl benzene sulfonate. The above emulsifier types have the characteristics of strong thermal stability. By preferably using this type of emulsifier, the yellowing phenomenon caused by the residual traditional anionic emulsifier (such as sodium dodecyl sulfate and fatty alcohol polyoxyethylene ether sulfate emulsifier) ​​during processing can be further avoided.

[0031] In some embodiments, the initiator is selected from potassium persulfate and / or sodium persulfate;

[0032] Preferably, the neutralizing agent is KOH and / or NaOH;

[0033] Preferably, the accelerator is a compound of ferrous sulfate and EDTA, preferably a compound in which the mass ratio of the two is 1:(1-3);

[0034] Preferably, the oxidant is one or both of tert-butyl hydroperoxide (TBHP) and cumene hydroperoxide;

[0035] Preferably, the reducing agent is one or more of sodium bisulfite, sodium bleaching agent, and sodium metabisulfite.

[0036] In some embodiments, in said 2), the mass ratio of the bottom initiator to the dripping initiator is 1:(1-3);

[0037] Preferably, the total amount of the initiator in 2) is 0.5-1.5 parts, preferably 0.6-1.3 parts;

[0038] Preferably, the mass concentration of the initiator solution is 3-6wt%.

[0039] In some embodiments, in step 3), the dropwise addition time of the shell pre-emulsion I and the dropwise addition initiator is 1-3 h;

[0040] Preferably, the neutralizing agent is added dropwise for 1-20 min and the insulation time is 10-30 min.

[0041] In some embodiments, in step 4), the core layer monomer solution II is added dropwise for 2-5 hours.

[0042] In some embodiments, the neutralizing agent is added in an amount such that the pH of the emulsion after neutralization is 7-9;

[0043] Preferably, the amount of the accelerator is preferably 0.02-0.2 parts, preferably 0.05-0.1 parts;

[0044] Preferably, the amount of the oxidant is 4-10 parts, preferably 6-9 parts;

[0045] Preferably, the reducing agent is used in an amount of 3-8 parts, preferably 5-7 parts;

[0046] Preferably, the amount of water used as the primer in step 3) is 1200-2000 parts, preferably 1300-1800 parts.

[0047] In some embodiments, the spraying process is specifically spray drying the emulsion through a pressure spray dryer.

[0048] The present invention also provides an application of the thermoplastic resin modifier prepared by the method described above as a toughening modifier for thermoplastic resin, especially as a toughening modifier for PMMA resin.

[0049] The modifier prepared by the present invention has a significantly reduced emulsifier dosage, and can fundamentally solve the yellowing phenomenon caused by the decomposition of the emulsifier when applied to the processing procedures of thermoplastic resins such as PMMA, thereby ensuring the excellent optical properties, impact resistance, and processability of the resin. DETAILED DESCRIPTION

[0050] The present invention is further described below by means of specific examples. The examples described in the present invention are only used to illustrate the present invention and do not limit the scope of the present invention.

[0051] Unless otherwise specified, the sources of raw materials in the following examples and comparative examples of the present invention were obtained from commercial channels.

[0052] The test methods mainly involved in the specific implementation of the present invention are as follows:

[0053] Optical properties: PMMA resin was pressed into 2 mm tablets on a tablet press, and its optical properties were tested on a photometric haze meter according to the ASTM D-1003 test method.

[0054] Mechanical properties: PMMA resin was made into a standard impact specimen with a thickness of 4 mm according to ASTM D256. A V-shaped notch was cut on the specimen with a notching machine to measure the cantilever beam notched impact strength.

[0055] Yellowing performance: PMMA resin was pressed into 3 mm tablets on a tablet press, and the yellowness value and b value were tested on a yellowness detector according to the method in GB / T39822.

[0056] [Example 1]

[0057] Prepare the modifier as follows:

[0058] 1) Prepare shell layer pre-emulsion I and core layer monomer solution II;

[0059] Shell pre-emulsion I: 600 g of methyl methacrylate, 40 g of methyl acrylate, 160 g of methacrylic acid, 6 g of n-dodecyl mercaptan, 1.2 g of sodium dodecylbenzene sulfonate, and 150 g of water.

[0060] Core layer monomer solution II: 640 g of butyl acrylate, 160 parts of styrene, and 1.6 g of ethylene glycol dimethacrylate.

[0061] 2) Weigh 0.3g of sodium persulfate and dissolve it in 5g of deionized water to prepare a bottom initiator solution; weigh 0.9g of sodium persulfate and dissolve it in 15g of deionized water to prepare a dropwise initiator solution;

[0062] 3) Use 1700g water as the base liquid, heat the reactor to 85°C; add the initiator at the bottom of the reactor at once, mix well, then drop the shell pre-emulsion I and the initiator to carry out the shell polymerization reaction; drop for 3 hours. After the drop is complete, immediately drop 30wt% sodium hydroxide until the pH is 8, drop for 10 minutes, and keep warm for 20 minutes;

[0063] 4) Cooling the reactor to 50° C., adding the core layer monomer solution II dropwise for 3 hours; then adding a promoter, an oxidant and a reducing agent; cooling and discharging; wherein the promoter is prepared by dissolving 0.06 g EDTA and 0.02 g ferrous sulfate in 2 g water; the oxidant is prepared by dissolving 9 g TBHP in 20 g water; and the reducing agent is prepared by dissolving 6.5 g bleaching agent in 20 g water.

[0064] 5) spray drying the emulsion by a pressure spray dryer to obtain a modifier.

[0065] [Example 2-6]

[0066] Referring to the process in Example 1, the conditions were adjusted as shown in Table 1 to prepare the modifiers in Examples 2-6, respectively.

[0067] Table 1

[0068]

[0069]

[0070]

[0071] [Comparative Example 1]

[0072] 1) Prepare shell layer pre-emulsion I and core layer monomer solution II;

[0073] Core layer monomer solution I: 300 g deionized water, 4 g sodium dodecylbenzene sulfonate, 160 g styrene, 640 g butyl acrylate, 1.6 g ethylene glycol dimethacrylate and stir well.

[0074] Shell pre-emulsion II: 300 g of deionized water, 7 g of sodium dodecylbenzene sulfonate, 760 g of methyl methacrylate, 40 g of methyl acrylate and 5 g of n-dodecyl mercaptan were prepared in pre-emulsification kettle 1 and stirred thoroughly.

[0075] 2) Weigh 0.3 g of sodium persulfate and dissolve it in 5 g of deionized water to prepare a bottom initiator solution; weigh 1.0 g of sodium persulfate and dissolve it in 15 g of deionized water to prepare a dropwise initiator solution;

[0076] 3) Use 1300g of water as the base liquid, heat the reactor to 85°C; add the initiator at the bottom of the reactor at once, mix well, drop the core layer pre-emulsion I and the initiator, and carry out the core layer polymerization reaction; drop for 3 hours. After the drop is complete, keep warm for 1 hour; drop the shell layer pre-emulsion II and the initiator, and carry out the shell layer polymerization reaction, and drop for 3 hours;

[0077] 4) After the dropwise addition is completed, the reaction kettle is cooled to 40° C. to obtain an emulsion;

[0078] 5) Weigh 1000g of the obtained emulsion in a reaction flask and control the temperature to 60°C, add a flocculant solution (prepared by 15g of magnesium sulfate and 1600g of dilution water) to the flask, add for 1h, raise the temperature to 85°C and keep it for 1h after the addition is completed, and then cool it to 50°C after the insulation is completed. Centrifuge and dry the obtained turbid solution to obtain the modifier powder.

[0079] [Comparative Example 2]

[0080] 1) Prepare shell layer pre-emulsion I and core layer monomer solution II;

[0081] Core layer monomer solution I: 300 g deionized water, 4 g sodium dodecylbenzene sulfonate, 160 g styrene, 640 g butyl acrylate, 1.6 g ethylene glycol dimethacrylate and stir well.

[0082] Shell pre-emulsion II: 300 g of deionized water, 7 g of sodium dodecylbenzene sulfonate, 760 g of methyl methacrylate, 40 g of methyl acrylate and 5 g of n-dodecyl mercaptan were prepared in pre-emulsification kettle 1 and stirred thoroughly.

[0083] 2) Weigh 0.3 g of sodium persulfate and dissolve it in 5 g of deionized water to prepare a bottom initiator solution; weigh 1.0 g of sodium persulfate and dissolve it in 15 g of deionized water to prepare a dropwise initiator solution;

[0084] 3) Use 1300g of water as the base liquid, heat the reactor to 85°C; add the initiator at the bottom of the reactor at once, mix well, drop the core layer pre-emulsion I and the initiator, and carry out the core layer polymerization reaction; drop for 3 hours. After the drop is complete, keep warm for 1 hour; drop the shell layer pre-emulsion II and the initiator, and carry out the shell layer polymerization reaction, and drop for 3 hours;

[0085] 4) After the addition is completed, the reactor is cooled to 40°C;

[0086] 5) spray drying the emulsion by a pressure spray dryer to obtain a modifier powder.

[0087] The PMMA resin was modified with the modifiers provided in the embodiments and comparative examples (the modification methods are as follows), and the performance tests shown in Table 2 were performed on the obtained modified resin.

[0088] The modifier and PMMA resin (Wanhua HD04) were mixed and granulated in a twin-roll mixer of Thermo-Jakke of Germany at a processing temperature of 220° C. and a mixing time of 5 min to obtain a modified PMMA resin.

[0089] Table 2

[0090]

[0091] From the test results in Table 2, it can be seen that after the modifier powder provided by Examples 1-6 of the present invention is used to toughen and modify PMMA resin, the resulting modified resin has the advantages of good optical properties, high impact strength, and good yellowing resistance. Comparative Examples 1 and 2 prepare modifiers by traditional core-shell emulsion polymerization process, and after being applied to PMMA resin modification, the optical properties and yellowing resistance of the product are affected to varying degrees, especially Comparative Example 2 is powdered by spray drying on the basis of traditional core-shell emulsion polymerization process, which seriously affects the haze and yellowing resistance of PMMA resin.

[0092] The above is only a preferred embodiment of the present invention. It should be pointed out that ordinary technicians in this field can make several improvements and supplements without departing from the method of the present invention. These improvements and supplements should also be regarded as the scope of protection of the present invention.

Claims

1. A method for preparing a thermoplastic resin modifier, characterized in that: The preparation process includes the following: 1) preparing a shell layer pre-emulsion I and a core layer monomer solution II according to parts by weight; Shell pre-emulsion I: 500-700 parts of hard monomer, preferably 550-650 parts, Soft monomer 10-80 parts, preferably 20-70 parts, 120-180 parts of acid functional monomer, preferably 130-170 parts, Chain transfer agent 5-11 parts, preferably 6-10 parts, Emulsifier 0.5-5 parts, preferably 1-4 parts, 120-220 parts of water, preferably 130-200 parts, Nuclear layer monomer solution II: Soft monomer 600-700 parts, preferably 610-680 parts; 100-200 parts of hard monomer, preferably 120-190 parts; 0.5-5 parts of cross-linking monomer, preferably 1-3 parts; 2) Prepare an initiator solution and divide it into two parts, one as the bottom initiator and the other as the dropwise initiator; 3) Using water as the primer, the reactor is heated to 80-90°C; adding the initiator at the bottom of the reactor at one time, mixing evenly, then dropping the shell pre-emulsion I and the initiator to carry out the shell polymerization reaction; after sufficient reaction, dropping the neutralizer and keeping the temperature; 4) Cooling the reactor to 40-60°C, adding the core layer monomer solution II dropwise, and then adding the accelerator, oxidant and reductant; cooling and discharging; 5) Powdering the emulsion through a spraying process to obtain the modifier.

2. The method for preparing a thermoplastic resin modifier according to claim 1, characterized in that: The hard monomer is one or two of styrene and methyl methacrylate; Preferably, the soft monomer is one or more of isooctyl acrylate, butyl acrylate, ethyl acrylate, and methyl acrylate; Preferably, the acid functional monomer is one or more of acrylic acid and methacrylic acid; Preferably, the cross-linking monomer is one or more of ethylene glycol dimethacrylate, butanediol dimethacrylate, and divinylbenzene.

3. The method for preparing a thermoplastic resin modifier according to claim 1, characterized in that: The chain transfer agent is one or both of dodecyl mercaptan and n-octyl mercaptan; Preferably, the emulsifier is one or both of disodium dodecyl diphenyl ether sulfonate and sodium dodecyl benzene sulfonate.

4. The method for preparing a thermoplastic resin modifier according to any one of claims 1 to 3, characterized in that: The initiator is selected from potassium persulfate and / or sodium persulfate; Preferably, the neutralizing agent is KOH and / or NaOH; Preferably, the accelerator is a compound of ferrous sulfate and EDTA, preferably a compound in which the mass ratio of the two is 1:(1-3); Preferably, the oxidant is one or both of tert-butyl hydroperoxide and cumene hydroperoxide; Preferably, the reducing agent is one or more of sodium bisulfite, sodium bleaching powder, and sodium metabisulfite.

5. The method for preparing a thermoplastic resin modifier according to any one of claims 1 to 4, characterized in that: In the above 2), the mass ratio of the bottom initiator to the dropwise added initiator is 1:(1-3); Preferably, the total amount of the initiator in 2) is 0.5-1.5 parts, preferably 0.6-1.3 parts; Preferably, the mass concentration of the initiator solution is 3-6wt%.

6. The method for preparing a thermoplastic resin modifier according to any one of claims 1 to 5, characterized in that: In step 3), the dropwise addition time of the shell pre-emulsion I and the dropwise addition initiator is 1-3 hours; Preferably, the neutralizing agent is added dropwise for 1-20 min and the insulation time is 10-30 min.

7. The method for preparing a thermoplastic resin modifier according to any one of claims 1 to 6, characterized in that: In step 4), the core layer monomer solution II is added dropwise for 2-5 hours.

8. The method for preparing a thermoplastic resin modifier according to any one of claims 1 to 7, characterized in that: The neutralizing agent is added in an amount such that the pH of the emulsion after neutralization is 7-9; Preferably, the amount of the accelerator is 0.02-0.2 parts, preferably 0.05-0.1 parts; Preferably, the amount of the oxidant is 4-10 parts, preferably 6-9 parts; Preferably, the reducing agent is used in an amount of 3-8 parts, preferably 5-7 parts.

9. The method for preparing a thermoplastic resin modifier according to any one of claims 1 to 8, characterized in that: The spraying process specifically involves spray drying the emulsion through a pressure spray dryer.

10. Use of the thermoplastic resin modifier prepared by the method according to any one of claims 1 to 9 as a toughening modifier for thermoplastic resins, especially as a toughening modifier for PMMA resins.

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