CN103254365B - Method for preparing ASA (Acrylonitrile-Styrene-Acrylate) copolymer latex by using water-solubility redox initiator at low temperature - Google Patents

Abstract

The invention discloses a method for preparing ASA (Acrylonitrile-Styrene-Acrylate) copolymer latex by using a water-solubility redox initiator at low temperature. The method comprises unit processes of preparing polyacrylate seeds, preparing a polyacrylate core, preparing an ASA resin shell and post processing. The water-solubility initiator adopted by the method can initiate polymerization at a lowest temperature of 35 DEG C and reach a high conversion rate. The method has the characteristics of good repeatability, warm reaction condition, low energy consumption, easiness in operation and low price of raw materials, so that the industrial implementation is facilitated.

Description

A kind of method that adopts water-soluble redox initiator to prepare ASA copolymer latex at low temperature

1. Technical field

The invention relates to a preparation method of acrylate-styrene-acrylonitrile ternary graft copolymer, in particular to a method for preparing ASA copolymer latex at low temperature by using a water-soluble redox initiator.

2. Background technology

ASA resin, also known as AAS resin, is a graft copolymer composed of acrylate, styrene and acrylonitrile (Acrylate-Styrene-Acrylonitrile), which presents styrene acrylonitrile (SAN) resin as the continuous phase and acrylate rubber Sea-island structure of the dispersed phase. Styrene endows it with luster and processability, acrylonitrile endows it with rigidity and chemical resistance, acrylate rubber endows it with impact resistance and aging resistance, and the copolymerization of the three substances makes ASA resin have excellent performance.

ASA resin was first industrialized by German BASF company in 1968, and its trade name was Luran ^® S. In the early 1970s, Japan realized the industrialization of ASA resin by Hitachi Chemical Industry Co., Ltd., and the trade name was VITAX. In 2003, GE Plastics, a subsidiary of General Electric Company of the United States, launched a new generation of ASA resin product with better performance, Jule resin, which is more resistant to aging, coloring and gloss. The trade name is GELOY ^® XTW . At present, the manufacturers of ASA resin in the world mainly include: German BASF Company, Japan Hitachi Chemical Co., Ltd., Japan UMGABS Co., Ltd., American General Electric Company, Dow Chemical Company, etc.

The research work related to ASA resin in my country is relatively small. From the early 1990s to the present, Beijing University of Chemical Technology, Zhejiang University, Lanhua Research Institute, and Dalian University of Technology have carried out related research work. my country's ASA resin has not yet achieved industrial production, and all aspects of research work need to be further in-depth.

The initiation system of ASA resin generally adopts two methods, namely, thermal initiation and redox initiation. The thermal initiation reaction temperature is relatively high, which requires high operability and high energy consumption. Therefore, redox systems are generally used in industrial applications (J. Herbig, I. 0. Salyer. Monsanto Co., US3118855[P]. 1960; H. P. Siebel, H. W. Otto. BASFAG, DE1238207 [P]. 1963). The redox system is divided into two categories: water-soluble and oil-soluble. Oil-soluble initiators are one of the current research hotspots (Liu Zhenguo, Han Ye, Zhang Huixuan, Polymerization Kinetics of Butyl Acrylate/Styrene-Acrylonitrile Emulsion, Polymer Materials Science and Engineering, 2010,8:12-15[J]), in ASA emulsion polymerization, most people's research focus has been on oil-soluble initiators or the combination of oil-soluble and water-soluble initiators, but due to The post-treatment process of oil-soluble initiators produces more or less toxic substances, which is not conducive to the green production of products. However, all water-soluble initiator systems not only perfectly solve these problems, but also have mild reaction conditions, low energy consumption, and easy operation. , The characteristics of low raw material prices are convenient for industrial implementation. In addition, since the water-soluble initiator has a wide range of sources, the advantages of no toxic and side effects are gradually being paid attention to (Cheng Yanling, Xu Zushun, Redox Initiated Soap-free Emulsion Polymerization to Prepare Monodisperse Thermosensitive Microspheres, Polymer Materials Science and Engineering, 2008, 12 : 38-42; Xueping Chen, Zhixue Weng, Polymerization Kinetics of Sodium Acrylate Initiated by Ammonium Persulfate/Aliphatic Amine, Chemical Reaction Engineering and Technology, 2004, 9:245-249).

Commonly used water-soluble redox systems such as persulfate-thiol, because thiol only acts as a molecular weight regulator during the styrene emulsion polymerization reaction, it does not greatly promote the polymerization reaction, so that the molecular weight after polymerization Low mechanical strength cannot meet the requirements of use; another example is hydrogen peroxide-ferrous salt and organic hydrogen peroxide-ferrous salt, which contain iron ions after polymerization, which has a great impact on the color of the product, and the production cost is high.

3. Contents of the invention

The present invention aims to provide a method for preparing ASA copolymer latex at low temperature by using a water-soluble redox initiator, select a relatively common and cheap water-soluble redox system, and control its reaction process, at a lower temperature by Emulsion polymerization successfully prepared ASA resin with higher impact strength.

The invention adopts an emulsion polymerization method to initiate polymerization through a water-soluble oxidizing agent and a reducing agent, and solves technical problems such as difficult control and poor repeatability of the reaction of two water-soluble monomers.

The present invention solves technical problem and adopts following technical scheme:

The present invention adopts the method for low-temperature preparation of ASA copolymer latex of water-soluble redox initiator, is characterized in that following steps are operated:

1) Preparation of polyacrylate seeds:

Under the protection of nitrogen, add 15-25% emulsifier into deionized water, disperse evenly, add 25-75% core layer monomer, stir well, add 10-20% oxidant and 10-20% Reducing agent, react at 35-60°C for 2-4h to obtain seed emulsion;

2) Preparation of polyacrylate core

Add 20-40% oxidant dropwise to the seed emulsion in step 1), and then add the core layer monomer pre-emulsion dropwise to the reaction solution, and react at 35-60°C after dropping the core layer monomer pre-emulsion 2 -4 hours to obtain a polyacrylate core emulsion, and the dropwise addition of the core layer monomer pre-emulsion is controlled within 1-2 hours. The size of the elastomer particles can be controlled by changing the amount of monomer added to the core layer.

The core monomer pre-emulsion is composed of the remaining core monomer, 5-20% shell monomer, 25-35% emulsifier, cross-linking agent, 20-40% reducing agent and deionized Emulsified by water stirring;

3) Preparation of ASA resin shell

Add the remaining amount of oxidant dropwise to the polyacrylate core emulsion in step 2), and then add the shell monomer pre-emulsion to the reaction solution dropwise, and react at 35-60°C after the shell monomer pre-emulsion is dropped ASA emulsion with a solid content of 45-55% was obtained in 2-4 hours; the dropwise addition of the shell monomer pre-emulsion was controlled within 1-2 hours;

The shell monomer pre-emulsion is obtained by stirring and emulsifying the remaining shell monomer, the remaining emulsifier, the remaining reducing agent and deionized water;

4) Post-processing

Add 5% NaCl aqueous solution to the ASA emulsion to break the emulsion. The volume ratio of ASA emulsion to NaCl solution is 1:1. After suction filtration, washing and drying, ASA resin is obtained.

The modified ASA resin powder was injection molded to obtain a resin sample, and the tensile properties were tested according to GB/T1040.2-2006.

Each raw material constitutes by mass parts:

10-90 parts of nuclear layer monomer,

Shell monomer 90-10 parts,

Emulsifier 0.6-3 parts,

Oxidizing agent 0.2-1 part,

0.2-0.6 parts of reducing agent,

0.5-2 parts of cross-linking agent;

The core layer monomer is selected from one or more of n-butyl acrylate (BA), n-butyl methacrylate, ethyl acrylate, propyl acrylate, and hydroxyethyl acrylate;

The core layer monomer also includes styrene and/or acrylonitrile.

The shell monomer is selected from one or more of styrene, α-methylstyrene, acrylonitrile, and methyl methacrylate;

The emulsifier is an anionic emulsifier or an ionic-nonionic composite emulsifier, preferably sodium dodecyl sulfate (SDS).

The oxidizing agent is selected from potassium persulfate (KPS), sodium persulfate, ammonium persulfate, azobisisobutylamidine hydrochloride (AIBA, V-50), azobisisobutylimidazoline hydrochloride (AIBA , VA-044), azodicyanovaleric acid (ACVA, V-501) or azodiisopropylimidazoline (AIP, VA-061); the oxidizing agent is preferably KPS.

The reducing agent is selected from sodium bisulfite, sodium sulfite, sodium thiosulfate or diamine;

The crosslinking agent is selected from one or more of butanediol diacrylate, 1,6-hexanediol diacrylate (HDDA), methacrylic acid, allyl methacrylate, and dienylbenzene .

Each raw material is preferably in parts by mass:

15-25 parts of nuclear layer monomer,

Shell monomer 60-80 parts,

Emulsifier 0.7-1.5,

Oxidizing agent 0.4-0.6 part,

0.2-0.4 parts of reducing agent,

Cross-linking agent 1-1.5 parts.

The molar ratio of the oxidizing agent to the reducing agent is 1:0.6.

The reaction mechanism of redox system of the present invention is: X+AB→X ^{++ B-} +A

Wherein X is reducing agent, A-B is oxidizing agent. Whether the free radicals produced by the reaction have practical significance for the polymerization reaction depends on the strength of the A-B bond and the reducing ability of the reducing agent X. Since the use of a redox system greatly reduces the activation energy for generating free radicals, the use of a redox system can increase the polymerization reaction rate and increase the production capacity under the same reaction conditions; while maintaining a certain production capacity, it can be Lowering the reaction temperature improves the properties of the polymer.

The present invention characterizes the change of the molecular chain and the formation of the core-shell three-dimensional structure through the following performance indicators.

1. Conversion rate (C)

Where m ₁ is the mass of the weighing bottle; m ₂ is the total mass of the emulsion and the weighing bottle; m ₃ is the total mass of the solid obtained after drying and the weighing bottle; m ₄ is the quality of the polymerization inhibitor; W ₁ is the quality of the initiator W ₂ is the mass percent concentration of the monomer, W ₄ is the mass percent concentration of the polymerization inhibitor; W ₅ is the mass percent concentration of the emulsifier.

The sample was dried in a vacuum oven at 120°C for 48 hours to constant weight, weighed, and the conversion rate was calculated.

2. Grafting rate

Toluene was used as a solvent and extracted in a Soxhlet extractor. Finally, the grafting rate was calculated according to the above formula.

3. Particle size

The Nano-ZS90 Zeta potential instrument produced by Malvern Company in the United Kingdom was used to measure the particle size and distribution through non-invasive backscattering (NIBS) using dynamic light scattering (DLS).

4. Tensile strength

The modified ASA resin powder was injection molded to obtain a resin sample, and the tensile properties were tested according to GB/T1040.2-2006.

The present invention uses water as the dispersion medium, uses anionic emulsifier or ion-nonionic compound emulsifier as emulsification stabilizer, and water-soluble redox system as initiator to initiate polymerization. The method of the present invention has good repeatability and has reaction conditions Mild, low energy consumption, and easy to operate, it is convenient for industrial implementation.

4. Specific implementation

Example 1:

Each raw material constitutes by mass parts:

The preparation method is as follows:

1) Add 0.088 parts of SDS to deionized water under the protection of nitrogen, and add 3.7 parts of BA after the dispersion _is uniform. React at 60°C for 2h;

2) Add 0.054 parts of KPS aqueous solution dropwise to the reaction solution in step 1), and then add the core layer monomer pre-emulsion dropwise to the reaction solution, and react at 60°C for 3 hours;

The core layer monomer pre-emulsion is obtained by stirring and emulsifying 7.4 parts of BA, 4.4 parts of St, 2.2 parts of AN, 0.74 part of HDDA, 0.132 part of SDS, _0.04 part of NaHSO and deionized water;

3) Add 0.162 parts of KPS aqueous solution dropwise to the reaction solution in step 2), then add the shell monomer pre-emulsion dropwise to the reaction solution, and react at 60°C for 3 hours to obtain an ASA emulsion with a solid content of 50%;

The shell monomer pre-emulsion is obtained by stirring and emulsifying 17.8 parts of St, 8.9 parts of AN, 0.22 parts of SDS, 0.12 parts of NaHSO ₃ and deionized water.

4) Mix the ASA emulsion obtained above with 5% sodium chloride aqueous solution at a volume ratio of 1:1 for demulsification, and then heat and stir, wash with water, filter with suction, and dry to obtain ASA resin.

Embodiment 2: comparative example—thermal decomposition initiates

Each raw material constitutes by mass parts:

The preparation method is as follows:

1) Add 0.088 parts of SDS into deionized water under the protection of nitrogen, disperse evenly, add 3.7 parts of BA, stir evenly, add 0.054 parts of KPS aqueous solution dropwise, finish dropping within ten minutes, and react at 75°C for 2 hours;

2) Add 0.054 parts of KPS aqueous solution dropwise to the reaction solution in step 1), and then add the core layer monomer pre-emulsion dropwise to the reaction solution, and react at 75°C for 3 hours;

The core layer monomer pre-emulsion is obtained by stirring and emulsifying 7.4 parts of BA, 4.4 parts of St, 2.2 parts of AN, 0.74 parts of HDDA, 0.132 parts of SDS and deionized water;

3) Add 0.162 parts of KPS aqueous solution dropwise to the reaction solution in step 2), then add the shell monomer pre-emulsion dropwise to the reaction solution, and react at 75°C for 3 hours to obtain an ASA emulsion with a solid content of 48%;

The shell monomer pre-emulsion is obtained by stirring and emulsifying 17.8 parts of St, 8.9 parts of AN, 0.22 parts of SDS and deionized water.

4) Mix the ASA emulsion obtained above with 5% sodium chloride aqueous solution at a volume ratio of 1:1 for demulsification, and then heat and stir, wash with water, filter with suction, and dry to obtain ASA resin.

Example 3:

Each raw material constitutes by mass parts:

The preparation method is as follows:

1) Add 0.088 parts of SDS to deionized water under the protection of nitrogen, and add 3.7 parts of BA after the dispersion _is uniform. React at 60°C for 2h;

2) Add 0.054 parts of KPS aqueous solution dropwise to the reaction solution in step 1), and then add the core layer monomer pre-emulsion dropwise to the reaction solution, and react at 60°C for 3 hours;

The core layer monomer pre-emulsion is obtained by stirring and emulsifying 7.4 parts of BA, 4.4 parts of St, 2.2 parts of AN, 0.132 part of SDS, _0.04 part of NaHSO and deionized water;

3) Add 0.162 parts of KPS aqueous solution dropwise to the reaction solution in step 2), and then add the shell monomer pre-emulsion dropwise to the reaction solution, and react at 60°C for 3 hours to obtain an ASA emulsion with a solid content of 53%;

The shell monomer pre-emulsion is obtained by stirring and emulsifying 17.8 parts of St, 8.9 parts of AN, 0.22 parts of SDS, 0.12 parts of NaHSO ₃ and deionized water.

4) Mix the ASA emulsion obtained above with 5% sodium chloride aqueous solution at a volume ratio of 1:1 for demulsification, and then heat and stir, wash with water, filter with suction, and dry to obtain ASA resin.

Example 4:

Each raw material constitutes by mass parts:

The preparation method is as follows:

1) Add 0.088 parts of SDS into deionized water under the protection of nitrogen, and add 2.1 parts of BA after the dispersion _is uniform. React at 60°C for 2h;

2) Add 0.054 parts of KPS aqueous solution dropwise to the reaction solution in step 1), and then add the core layer monomer pre-emulsion dropwise to the reaction solution, and react at 60°C for 3 hours;

The core layer monomer pre-emulsion is obtained by stirring and emulsifying 4.3 parts of BA, 4.4 parts of St, 2.2 parts of AN, 0.74 part of HDDA, 0.132 part of SDS, _0.04 part of NaHSO and deionized water;

3) Add 0.162 parts of KPS aqueous solution dropwise to the reaction solution in step 2), and then add the shell monomer pre-emulsion dropwise to the reaction solution, react at 60°C for 3 hours to obtain an ASA emulsion with a solid content of 45-55% ;

The shell monomer pre-emulsion is obtained by stirring and emulsifying 21 parts of St, 10.5 parts of AN, 0.22 parts of SDS, 0.12 parts of NaHSO ₃ and deionized water.

4) Mix the ASA emulsion obtained above with 5% sodium chloride aqueous solution at a volume ratio of 1:1 for demulsification, and then heat and stir, wash with water, filter with suction, and dry to obtain ASA resin.

Example 5:

The steps in this example are the same as in Example 1, except that the reaction temperature in step 1), step 2) and step 3) is 45°C.

Embodiment 6:

Each step of this embodiment is the same as that of Embodiment 1, except that the mass fraction of HDDA is 1 part.

Embodiment 7:

Each raw material constitutes by mass parts:

The preparation method is as follows:

1) Add 0.088 parts of SDS to deionized water under the protection of nitrogen, and add 3.7 parts of BMA after the dispersion _is uniform. React at 60°C for 2h;

2) Add 0.054 parts of KPS aqueous solution dropwise to the reaction solution in step 1), and then add the core layer monomer pre-emulsion dropwise to the reaction solution, and react at 60°C for 3 hours;

The core layer monomer pre-emulsion is obtained by stirring and emulsifying 7.4 parts of BMA, 4.4 parts of MMA, 2.2 parts of AN, 0.74 parts of HDDA, 0.132 parts of SDS, _0.04 parts of NaHSO and deionized water;

3) Add 0.162 parts of KPS aqueous solution dropwise to the reaction solution in step 2), then add the shell monomer pre-emulsion dropwise to the reaction solution, and react at 60°C for 3 hours to obtain an ASA emulsion with a solid content of 50%;

The shell monomer pre-emulsion is obtained by stirring and emulsifying 17.8 parts of MMA, 8.9 parts of AN, 0.22 parts of SDS, 0.12 parts of NaHSO ₃ and deionized water.

4) Mix the ASA emulsion obtained above with 5% sodium chloride aqueous solution at a volume ratio of 1:1 for demulsification, and then heat and stir, wash with water, filter with suction, and dry to obtain ASA resin.

Embodiment 8:

Each raw material constitutes by mass parts:

The preparation method is as follows:

1) Add 0.088 parts of SDS to deionized water under the protection of nitrogen, and add _3.7 parts of BA after the dispersion is uniform. React at 60°C for 2h;

2) Add 0.054 parts of AIBA aqueous solution dropwise to the reaction solution in step 1), and then add the core layer monomer pre-emulsion dropwise to the reaction solution, and react at 60°C for 3 hours;

The core layer monomer pre-emulsion is obtained by stirring and emulsifying 7.4 parts of BA, 4.4 parts of St, 2.2 parts of AN, 0.74 part of DVB, 0.132 part of SDS, _0.04 part of NaHSO and deionized water;

3) Add 0.162 parts of AIBA aqueous solution dropwise to the reaction solution in step 2), and then add the shell monomer pre-emulsion dropwise to the reaction solution, and react at 60°C for 3 hours to obtain an ASA emulsion with a solid content of 50%;

The shell monomer pre-emulsion is obtained by stirring and emulsifying 17.8 parts of St, 8.9 parts of AN, 0.22 parts of SDS, 0.12 parts of NaHSO ₃ and deionized water.

4) Mix the ASA emulsion obtained above with 5% sodium chloride aqueous solution at a volume ratio of 1:1 for demulsification, and then heat and stir, wash with water, filter with suction, and dry to obtain ASA resin.

The results of various performance measurements.

Table 1 ASA emulsion performance test

Table 1 is the relevant performance test of ASA emulsion. It can be seen from Table 1 that the reaction conversion rate at 45 °C is slightly lower than that at 60 °C, but it is still higher; increasing the amount of monomer added in the third stage can obtain large particle size particles.

Table 2 Comparison of tensile mechanical properties of ASA resin

Table 2 shows the test results of the tensile mechanical properties of the ASA resin prepared in the examples. The results show that the tensile strength of the ASA resin prepared by using the water-soluble redox system is significantly better than that of the ASA resin prepared by using the thermal decomposition initiator (Example 2).

Claims (3)

1. adopt a method for water soluble, redox initiator low-temperature growth ASA copolymer emulsion, it is characterized in that operating according to the following steps:

1) under nitrogen protection the emulsifying agent of 15-25% is added in deionized water, after being uniformly dispersed, add the nuclear layer monomer of 25-75%, after stirring, drip the oxygenant of 10-20% and the reductive agent of 10-20% respectively simultaneously, in 35-60 DEG C of reaction 2-4h;

2) to step 1) reaction solution in drip the oxygenant of 20-40%, in reaction solution, drip nuclear layer monomer pre-emulsion again after dripping off, in 35-60 DEG C of reaction 2-4 hour;

Described nuclear layer monomer pre-emulsion is obtained by the reductive agent of the emulsifying agent of the shell monomers of the nuclear layer monomer of surplus, 5-20%, 25-35%, linking agent, 20-40% and deionized water and stirring emulsification;

3) to step 2) reaction solution in drip the oxygenant of surplus, in reaction solution, drip shell monomers pre-emulsion again after dripping off, within 2-4 hour, obtain the ASA emulsion of solid content 45-55% in 35-60 DEG C of reaction;

Described shell monomers pre-emulsion is obtained by the emulsifying agent of the shell monomers of surplus, surplus, the reductive agent of surplus and deionized water and stirring emulsification;

Each raw material is configured to by mass fraction:

Described nuclear layer monomer is selected from one or more in n-butyl acrylate, n-BMA, ethyl propenoate, propyl acrylate, Hydroxyethyl acrylate;

Described shell monomers is selected from one or more in vinylbenzene, alpha-methyl styrene, vinyl cyanide, methyl methacrylate;

Described emulsifying agent is anionic emulsifier or ion-non-ionic composite emulsifying agent;

Described oxygenant is selected from Potassium Persulphate, Sodium Persulfate or ammonium persulphate;

Described reductive agent is selected from sodium bisulfite, S-WAT, Sulfothiorine or diamine;

Described linking agent is selected from one or more in butyleneglycol double methacrylate, 1,6 hexanediol diacrylate, allyl methacrylate(AMA), dialkylene benzene.

2. preparation method according to claim 1, is characterized in that each raw material is configured to by mass fraction:

3. preparation method according to claim 1, is characterized in that:

The mol ratio of described oxygenant and described reductive agent is 1:0.6.