Polyalkyl acrylate latex, preparation method thereof and ASA (Acrylate Styrene Acrylate) resin

Abstract

The invention provides polyacrylic acid alkyl ester latex, a preparation method thereof and ASA (acrylonitrile styrene acrylate) resin. Polymer films prepared from the polyalkyl acrylate latex have a wetting angle of 35 DEG to 75 DEG to pure water and an anchoring charge density of 0.2% to 6.0% by adding a hydrophilic monomer to copolymerize with the alkyl acrylate and hydrophilically modifying the polyalkyl acrylate polymer chain with a hydrophilic initiator. When the polyacrylic acid alkyl ester latex is subjected to subsequent emulsion graft polymerization, the tendency of the styrene-acrylonitrile copolymer entering the latex is increased, and the embedded styrene-acrylonitrile copolymer has an expansion effect on rubber and can improve the toughening efficiency of the rubber on one hand, and also increases the strength and modulus of the rubber on the other hand, so that the toughness of the rubber is improved. And the resin rigidity is improved. The ASA resin composition prepared from the polyacrylic acid alkyl ester latex has excellent impact strength and mechanical rigidity.

Description

Technical Field

[0001] This invention belongs to the field of polymers, specifically relating to a polyalkyl acrylate latex and ASA resin. Background Technology

[0002] ASA (acrylate-styrene-acrylonitrile graft copolymer) resin is widely used in the automotive and building materials industries due to its excellent weather resistance. However, compared with ABS resin, ASA resin is usually inferior in mechanical properties, especially impact resistance, and it is difficult to simultaneously achieve high impact strength and high mechanical rigidity.

[0003] Existing technologies have made numerous attempts to improve the performance of ASA resin: German patent DE1260135B improved impact resistance and aging resistance by combining graft copolymers with acrylate copolymers, but failed to achieve higher impact strength. Patent TWI229680B solved the problems of poor weather resistance and mechanical strength through additive reinforcement, but its improved impact resistance came at the cost of sacrificing mechanical rigidity.

[0004] CN101864040A discloses a method for preparing a butyl acrylate-styrene-acrylonitrile graft copolymer, which adopts a core-shell structure and uses methacrylic acid as a crosslinking agent in the core layer. The aim is to improve mechanical properties by forming a core-shell chemical bond through carboxyl dehydration. CN103242478A discloses an acrylate agglomerating agent and its application. This agglomerating agent contains hydrophilic monomers (such as acrylic acid), but its use is as a small-scale (0.1-5%) processing aid to agglomerate and increase the particle size of the base latex, thereby improving the impact resistance of ASA resin. CN103570882A discloses an ASA graft copolymer resin powder, which adopts a core-shell structure and uses functional monomers (such as methacrylic acid). This patent aims to simplify the process and reduce costs by synthesizing large-particle-size latex in a one-step method and using suspension grafting. CN105647047A discloses a chemically modified ASA resin, which uses multi-step seed emulsion polymerization to form a PBA elastomer with a core-shell structure, and introduces methacrylic acid to improve gloss and weather resistance. The core of this patent lies in the complex core-shell structure design and specific application (ASA / PVC co-extrusion), rather than controlling the bulk hydrophilicity / hydrophobicity of the rubber phase through simple homogeneous polymerization. CN117304411A discloses a method for preparing high-rubber ASA powder, which uses a self-made composite emulsifier and nano-polyacrylate microsphere emulsion, aiming to solve problems such as low grafting efficiency and easy agglomeration. This patent's technical solution is complex, focusing on the emulsifier and nanomaterials.

[0005] As can be seen from the existing technologies described above, although improving a certain aspect of the properties of ASA resin by introducing hydrophilic components or specific structures has become a technical approach in this field, these studies have mostly focused on constructing core-shell structures, using agglomerating agents, or complex emulsion systems. These methods either aim to optimize a specific property (such as gloss or agglomeration efficiency) or to solve process problems (such as avoiding agglomeration or simplifying the process).

[0006] More importantly, existing technologies have not fully addressed and revealed the intrinsic relationship between the bulk hydrophilicity of the polyalkyl acrylate rubber phase and the anchored charge density on the rubber phase surface, and their synergistic gain relationship with the macroscopic mechanical properties achieved in the final ASA resin, particularly impact resistance and rigidity. There is a lack of technical solutions in this field that actively guide the graft copolymerization process by precisely designing and controlling the hydrophilicity parameters of the rubber phase polymer, thereby simultaneously and significantly improving the resin's toughness and rigidity. Summary of the Invention

[0007] In view of the above-mentioned problems in the prior art, the present invention has been made. One object of the present invention is to provide a polyalkyl acrylate latex, a method for preparing the same, and an ASA resin. The ASA resin prepared from the polyalkyl acrylate latex prepared by the present invention has excellent impact resistance and mechanical rigidity.

[0008] According to one aspect of the present invention, a polyalkyl acrylate latex is provided, which is prepared from raw materials comprising the following parts by weight:

[0009]

[0010] The polymer film prepared from the polyalkyl acrylate latex has a wetting angle of 35°-75° to pure water and an anchored charge density of 0.2-6.0%. The wetting angle is one of the core indicators for measuring the hydrophilicity of a material; the smaller the angle, the stronger the hydrophilicity of the material. When the polymer film prepared from the polyalkyl acrylate latex has a wetting angle greater than 75° to pure water, due to the low hydrophilicity of the polyalkyl acrylate rubber, styrene and acrylonitrile tend to graft onto the surface of the polyalkyl acrylate rubber during styrene-acrylonitrile graft polymerization, resulting in less internal grafting. Consequently, the tensile, gloss, and other rigidity properties of the prepared ASA resin will deteriorate. When the polymer film prepared from the polyalkyl acrylate latex has a wetting angle less than 35° to pure water, due to the excessive hydrophilicity of the rubber, styrene and acrylonitrile tend to graft internally during styrene-acrylonitrile graft polymerization. In severe cases, phase inversion may even occur, thus negating the original purpose of styrene and acrylonitrile coating the surface of the polyalkyl acrylate rubber to improve compatibility. Consequently, the impact resistance, gloss, and other properties of the prepared ASA resin will deteriorate. The anchored charge density of polyalkyl acrylate rubber is another key indicator for measuring the hydrophilicity of rubber. This indicator, together with the use of hydrophilic monomers, determines the degree of hydrophilicity of polyalkyl acrylate rubber. When the anchored charge density of the polyalkyl acrylate rubber is less than 0.2%, the rigidity and other properties of the prepared ASA resin will deteriorate due to the low hydrophilicity of the rubber. When the anchored charge density of the polyalkyl acrylate rubber is greater than 6%, the excessive hydrophilicity of the rubber will cause styrene and acrylonitrile to tend to internally graft during graft polymerization, thereby deteriorating the impact resistance and other properties of the prepared ASA resin.

[0011] In one embodiment of the present invention, the functional monomer refers to a vinyl monomer with a solubility ≥1.5g / 100g H2O at 20-25°C, preferably one or more of acrylic acid, methacrylic acid, methyl acrylate, hydroxyethyl methacrylate, hydroxyethyl acrylate, and glycidyl acrylate.

[0012] In one embodiment of the present invention, the initiator is selected from one or more inorganic peroxides, preferably one or more of hydrogen peroxide, potassium persulfate, sodium persulfate, and ammonium persulfate.

[0013] In one embodiment of the present invention, the crosslinking agent is a polymerizable monomer having a polyolefin double bond, selected from one or more of divinylbenzene, ethylene glycol dimethacrylate, triallyl isocyanurate, dicyclopentadienyl acrylate, and allyl methacrylate.

[0014] In one embodiment of the present invention, the alkyl acrylate monomer is selected from alkyl acrylates with an alkyl chain length of C1-C15, and is selected from one or more of methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, 2-ethylbutyl acrylate, octyl acrylate, 2-ethylhexyl acrylate, hexyl acrylate, heptyl acrylate, n-pentyl acrylate and lauryl acrylate, preferably including alkyl acrylates having an alkyl chain length of C1-C4, such as butyl acrylate, propyl acrylate, ethyl acrylate, methyl acrylate, and more preferably butyl acrylate.

[0015] In one embodiment of the present invention, the emulsifier is selected from one or more of potassium oleate, potassium rosinate, sodium dodecyl sulfate, sodium dodecylbenzene sulfonate, sodium dodecyl allyl sulfosuccinate, dipotassium C16-C18 alkenyl succinate, and dioctyl sodium sulfosuccinate.

[0016] In one embodiment of the present invention, the electrolyte is selected from one or more of potassium carbonate, sodium carbonate, potassium bicarbonate, sodium bicarbonate, sodium phosphate, sodium pyrophosphate, potassium pyrophosphate, and sodium tripolyphosphate.

[0017] In one embodiment of the present invention, the chain transfer agent is an alkyl thiol with a main carbon chain length of C8-C14, selected from one or more of tert-dodecyl thiol, n-dodecyl thiol, n-octyl thiol, tert-octyl thiol, octyl thiol, and tert-octyl thiol.

[0018] This invention also provides a method for preparing polyalkyl acrylate latex, comprising the following steps:

[0019] Deionized water, electrolyte, emulsifier, alkyl acrylate monomers, functional monomers, crosslinking agent, chain transfer agent and initiator are added to a reactor and stirred. Emulsion polymerization is carried out at 45-75℃ to obtain polyalkyl acrylate latex.

[0020] According to another aspect of the present invention, the present invention also provides an ASA resin prepared from a polyalkyl acrylate latex obtained by the method described herein.

[0021] In this invention, the production process of grafting, coagulating, dehydrating, and drying the prepared alkyl acrylate latex to obtain ASA powder, and then blending and granulating it with SAN resin to obtain ASA resin, can refer to the manufacturing technology of ABS resin, which is a conventional technology in this field. Specifically, the specific operations for obtaining ASA powder from alkyl acrylate latex through grafting, coagulation, filtration, dehydration, and drying can be found on pages 23-26 and 36-58 of the book "ABS Resin Production Practice and Application" by Suo Yanhui et al., and the specific operations for obtaining ABS resin by blending ABS powder with SAN resin and extruding and granulating it can be found on pages 68-74 of the same book.

[0022] Depending on its intended use, the ASA resin may also contain one or more additives selected from lubricants, antioxidants, antistatic agents, mold release agents, and UV stabilizers. Among these additives, the lubricant may be selected from ethylene bis-stearamide, polyethylene oxide wax, metal stearates, and various silicone oils, and the amount of the lubricant used may be 0-5 parts by weight, preferably 0.1-2 parts by weight, based on 100 parts by weight of the thermoplastic resin composition.

[0023] The ASA resin composition can be kneaded to provide a thermoplastic ASA resin. More specifically, the ASA resin is uniformly dispersed using a single-screw extruder or a twin-screw extruder. The dispersed composition is then passed through an underwater extruder and cut, and dried to obtain granular thermoplastic ASA resin.

[0024] The ASA resin prepared according to the present invention is used to prepare test specimens by extrusion and injection molding, and the cantilever beam impact strength measured at 1 / 4" according to ASTM D256 can reach 35 kJ / m. 2 Furthermore, according to ASTM D790, the bending strength of a 6.4 mm specimen tested at 10 mm / min under 23°C can reach over 75 MPa.

[0025] The beneficial effects of this invention are as follows: By adding hydrophilic functional monomers to copolymerize with alkyl acrylate or using hydrophilic initiators, the polyalkyl acrylate polymer chains are hydrophilically modified, resulting in a polyalkyl acrylate polymer exhibiting certain hydrophilicity. During subsequent emulsion graft polymerization, the tendency of the styrene-acrylonitrile copolymer to enter the interior of the polyalkyl acrylate increases. This styrene-acrylonitrile copolymer, once inside the polyalkyl acrylate rubber, expands the rubber, improving its toughening efficiency. Furthermore, the rigid styrene-acrylonitrile copolymer embedded within the polyalkyl acrylate rubber increases its strength and modulus, leading to improved resin rigidity. The ASA resin composition obtained by twin-screw blending the polyalkyl acrylate with SAN resin base material, lubricant, antioxidant, UV absorber, and other additives exhibits excellent impact strength and mechanical rigidity. Detailed Implementation

[0026] To facilitate understanding of the present invention, the following description, in conjunction with embodiments, will further illustrate the invention. It should be understood that the following embodiments are merely for a better understanding of the invention and do not imply that the invention is limited to these embodiments.

[0027] The wetting angle of the polyalkyl acrylate latex was obtained by the following method: approximately 5.0g of latex was dropped into a glass petri dish with a diameter of 3cm, and the latex was evenly dispersed at the bottom of the petri dish to form a liquid film. The petri dish was then placed stably in a forced-air oven at 45℃ and baked for more than 20 hours to obtain a functional polyalkyl acrylate rubber film. The rubber film was cut into 5 rubber discs with a diameter of approximately 5-8mm. The wetting angle was tested using a wetting contact angle tester (model DSA 100S) from KRUSS GmbH, Germany, under standard conditions (room temperature 25℃, humidity 55%). The average value of the 5 tests was taken to obtain the wetting angle of the functional polyalkyl acrylate latex.

[0028] The anchored charge density η of the polyalkyl acrylate latex is calculated by the following method:

[0029]

[0030] Example 1: Preparation of polyalkyl acrylate latex A1

[0031] 120 kg of deionized water, 0.1 kg of potassium carbonate, 0.1 kg of sodium dodecylbenzenesulfonate, 50 kg of butyl acrylate, 60 kg of isooctyl acrylate, 0.1 kg of divinylbenzene, and 0.11 kg of potassium persulfate were added to a reaction vessel and stirred. Nitrogen gas was introduced into the reaction vessel to 100 kPa, and then a vacuum was created to 8 kPa. This process was repeated several times to remove oxygen from the reaction vessel. The reaction vessel was then heated to 75 °C to obtain polyalkyl acrylate latex (A1). Calculations and tests showed that the anchoring charge density of the polyalkyl acrylate latex (A1) was 0.2%, and the wetting angle after film formation was 74.7 °C.

[0032] Examples 2-5: Preparation of polyalkyl acrylate latex A2-A5

[0033] The differences between Examples 2-5 and Example 1 are shown in Table 1. The other raw materials, experimental conditions and reaction steps are the same as those in Example 1.

[0034] Table 1. Feeding formulas and processes for Examples 1 and 2-5

[0035]

[0036]

[0037] Comparative Example 1: Preparation of Alkyl Acrylate Latex B1

[0038] The process of Example 5 was repeated, except that the initiator added in the reaction of Comparative Example 1 was oil-soluble azobisbutyronitrile. The other raw materials, addition amounts, experimental conditions and reaction steps were the same as in Example 5. After the reaction termination conditions of Example 5 were met, the temperature was lowered to stop the reaction, and alkyl acrylate latex B1 was obtained.

[0039] Comparative Example 2: Preparation of Alkyl Acrylate Latex B2

[0040] The process of Example 1 was repeated, except that the amount of potassium persulfate used was halved, that is, the amount of feed was changed to 0.055 kg. The other types and amounts of raw materials, experimental conditions and reaction steps were the same as in Example 1.

[0041] Comparative Example 3: Preparation of Alkyl Acrylate Latex B3

[0042] The process of Example 2 was repeated, except that the amounts of acrylic acid, methacrylic acid, and hydroxyethyl methacrylate were increased to 4.5 kg acrylic acid, 4.5 kg methacrylic acid, and 6.0 kg hydroxyethyl methacrylate, respectively. All other raw materials, experimental conditions, and reaction steps were the same as in Example 2.

[0043] Table 2 below summarizes the differences between the polyalkyl acrylate latexes prepared in Examples 1-5 and Comparative Examples 1-3.

[0044] Table 2. Differences between the polyalkyl acrylate latexes prepared in Examples 1-5 and Comparative Examples 1-3

[0045] Anchored charge density Wetting contact angle Example 1 0.20％ 74.7 Example 2 6.00％ 35.3 Example 3 0.46％ 70.7 Example 4 3.62％ 42.9 Example 5 2.00％ 55.3 Comparative Example 1 0.00％ 76.1 Comparative Example 2 0.10％ 87.3 Comparative Example 3 6.00％ 24.7

[0046] Furthermore, ASA resin was prepared using the polyalkyl acrylate latexes prepared in Examples 1-5 and Comparative Examples 1-3 in the following manner.

[0047] 1) Preparation of ASA grafted latex

[0048] Add 60 kg (by solids) of polyalkyl acrylate latex prepared in Examples 1-5 and Comparative Examples 1-3, 120 kg of deionized water, 0.001 kg of FeSO4·7H2O, 0.01 kg of disodium ethylenediaminetetraacetate, and 0.1 kg of sodium formaldehyde sulfoxylate to the reactor and start stirring. After heating the reactor to 50°C, continuously add a mixed pre-emulsion consisting of 0.2 kg of cumene hydroperoxide, 10.7 kg of styrene, 16.8 kg of acrylonitrile, 32.4 kg of methyl methacrylate, 0.5 kg of tert-dodecyl mercaptan, 3 kg of sodium dodecyl sulfate, and 25 kg of deionized water to the reactor. The continuous feeding time is 3 hours. After the feeding is completed, heat the reactor to 70°C and continue the reaction for 2 hours. Then cool the reactor to room temperature and stop stirring. Filter to obtain ASA grafted latex.

[0049] 2) Preparation of ASA adhesive powder

[0050] Add 6.0 kg of anhydrous calcium chloride and 120 kg of deionized water to the coagulation reactor and start stirring to fully dissolve the calcium chloride. Heat the coagulation reactor to 85°C and continuously feed 100 kg of ASA grafted latex prepared in step 1) into the coagulation reactor for 1 hour. After feeding is completed, heat the coagulation reactor to 95°C and keep it at that temperature for 1 hour. Cool the coagulation reactor to room temperature and filter, wash and dehydrate the coagulated slurry to obtain ASA wet latex powder. Dry the ASA wet latex powder in a fluidized bed dryer at 65°C until the moisture content is <1% to obtain ASA latex powder.

[0051] 3) ASA resin preparation, injection molding and performance testing

[0052] Using a twin-screw extruder at 200℃-220℃, LG Chem's MSAN resin (XT-500) was used as the continuous phase, and the ASA rubber powder prepared in step 2) was used as the dispersed phase. Lubricants, antioxidants, and UV stabilizers, in industry-standard amounts, were added as blending aids. The ASA resin was obtained by blending, extrusion, and granulation according to a polyalkyl acrylate rubber content of 21%. Recommended formulations are shown in the table below.

[0053] Table 3 Composition of Blending Formulation

[0054]

[0055]

[0056] The ASA resin particles prepared by extrusion were used to prepare various test specimens on an injection molding machine at 220°C. The performance was tested according to the following methods, and the results are shown in Table 4:

[0057] Impact resistance: ASTM D256-2006 Test method for impact resistance of plastics and electrical insulating materials.

[0058] Flexural strength: ASTM D790 Standard Test Method for Opacity and Transmittance of Transparent Plastics

[0059] Table 4. Performance comparison of ASA resins prepared in Examples 1-5 and Comparative Examples 1-3

[0060] <![CDATA[Impact strength (kJ / m 2 )]]> Bending strength (MPa) Example 1 36.9 80.7 Example 2 37.4 80.1 Example 3 39.7 79.3 Example 4 41.6 76.7 Example 5 42.6 75.1 Comparative Example 1 19.3 82.3 Comparative Example 2 28.7 75.3 Comparative Example 3 9.7 83.7

[0061] As can be seen from Table 4 above, unlike Comparative Examples 1-3, the ASA resin compositions obtained by adding hydrophilic monomers of the types and amounts described above to copolymerize with alkyl acrylates or using hydrophilic initiators of the specified types and amounts, and by twin-screw blending of the polyalkyl acrylates with SAN resin base, lubricant, antioxidant, UV absorber, and other additives, exhibit excellent impact strength and mechanical rigidity. However, when the types and amounts of hydrophilic monomers and water-soluble initiators deviate from those described in this invention, the resulting ASA resin compositions show varying degrees of degradation in impact strength and mechanical rigidity, or both are difficult to achieve simultaneously.

[0062] Finally, it should be noted that the above embodiments are only used to describe preferred embodiments of the present invention, and are not intended to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that various modifications and improvements made to the technical solutions of the present invention by means of modifications or equivalent substitutions should fall within the scope of protection defined by the claims of the present invention.

Claims

1. A polyalkyl acrylate latex comprising the following raw materials in parts by mass: wherein The polymer film prepared from the polyalkyl acrylate latex has a wetting angle of 35°-75° to pure water and an anchoring charge density of 0.2-6.0%.

2. The polyalkyl acrylate latex according to claim 1, characterized in that, The functional monomer refers to a vinyl monomer having a solubility of ≥1.5 g / 100 g H2O at 20-25 °C, preferably one or more of acrylic acid, methacrylic acid, methyl acrylate, hydroxyethyl methacrylate, hydroxyethyl acrylate, and glycidyl acrylate.

3. The polyalkyl acrylate latex according to claim 1 or 2, characterized in that, The initiator is selected from one or more of inorganic peroxides, preferably one or more of hydrogen peroxide, potassium persulfate, sodium persulfate, and ammonium persulfate.

4. The polyalkyl acrylate latex according to any one of claims 1 to 3, characterized in that, The crosslinking agent is a polymerizable monomer having multiple olefinic double bonds, selected from one or more of divinyl benzene, ethylene glycol dimethacrylate, triallyl isocyanurate, dicyclopentadiene acrylate, and allyl methacrylate.

5. The polyalkyl acrylate latex according to any one of claims 1 to 4, characterized in that, The alkyl acrylate monomer is selected from one or more of alkyl acrylate having an alkyl chain length of C1-C15, selected from methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, 2-ethylbutyl acrylate, octyl acrylate, 2-ethylhexyl acrylate, hexyl acrylate, heptyl acrylate, n-pentyl acrylate, and lauryl acrylate; preferably comprising alkyl acrylate having an alkyl chain length of C1-C4, more preferably one or more of butyl acrylate, propyl acrylate, ethyl acrylate, and methyl acrylate.

6. The polyalkyl acrylate latex according to any one of claims 1 to 5, characterized in that, The emulsifier is selected from one or more of potassium oleate, potassium abietate, sodium dodecyl sulfate, sodium dodecyl benzene sulfonate, sodium dodecyl allyl sulfosuccinate, C16-C18 alkenyl succinate dipotassium, and dioctyl sodium sulfosuccinate.

7. The polyalkyl acrylate latex according to any one of claims 1 to 6, characterized in that, The electrolyte is selected from one or more of potassium carbonate, sodium carbonate, potassium bicarbonate, sodium bicarbonate, sodium phosphate, sodium pyrophosphate, potassium pyrophosphate, and sodium tripolyphosphate.

8. The polyalkyl acrylate latex according to any one of claims 1 to 7, characterized in that, The chain transfer agent is an alkyl thiol having a main carbon chain length of C8-C14, selected from one or more of tert-dodecyl mercaptan, n-dodecyl mercaptan, n-octyl mercaptan, primary octyl mercaptan, secondary octyl mercaptan, and tertiary octyl mercaptan.

9. A process for preparing the polyalkyl acrylate latex according to any one of claims 1 to 8, comprising the steps of: The deionized water, electrolyte, emulsifier, alkyl acrylate monomer, functional monomer, crosslinking agent, chain transfer agent, and initiator are added to a reaction kettle and stirring is started, and an emulsion polymerization reaction is carried out at 45-75 °C to obtain a polyalkyl acrylate latex.

10. An ASA resin prepared from a feedstock comprising the polyalkyl acrylate latex of any one of claims 1-8 or the polyalkyl acrylate latex prepared by the method of claim 9; an Izod impact strength of > 35 kJ / m according to ASTM D256 measured at 1 / 4"; and a flexural strength of > 75 MPa according to ASTM D790 tested at 23°C on 6.4 mm bars at 10 mm / min. 2 , and a flexural strength of > 75 MPa according to ASTM D790 tested at 23°C on 6.4 mm bars at 10 mm / min.

Images