Development of acrylic co-polylactic emulsion water-based coating thickener (2)

2 Results and Discussion
Through experiments, it was found that the ratio of ethyl acrylates (EA abbreviated EA) to methyl acrylic acid (ABMA) was 1:1 (ester acid ratio), emulsifier EBL, CO436 dosage had a greater impact on the stability of emulsion, crosslinking agent, trigger dosage and reaction temperature, tick acceleration on the molecular weight of the emulsion polymer, mucus significantly.
effect of 2.1 emulsion dosage on emulsion granularity and stability
fixed experimental conditions: ester acid ratio of 1:1, reaction temperature seed polymerization (45 x 2) degrees C, shell core polymerization temperature (78 x 2 degrees C), causing Dosage 0.2% (in mixed monosome), crosslinking dose 0.01% (in mixed monosome), drop acceleration 2h, emulsifier on the stability of emulsion (natural storage does not break milk does not precipitate time by day) affect the law as seen in Table 1.As can be seen from Table 1, with the increase of emulsion dosage, the granularity of emulsion is getting smaller and smaller, the storage stability of the corresponding emulsion will be better and better, because in the process of reaction, the emulsion's oil-based hydrocarbon bond extends into the organic monosome, the emulsion's hydrophobic group extends into the water phase, the emulsizer and the organic phase are embedded together to form a stable O/W water-based oil-based dispersion system. At the same time, the addition of emulsion greatly reduces the surface tension of emulsion, and the particles formed by organic monosomes in water decrease with the increase of emulsion, so that the emulsion particles formed in the process of seed polymerization are smaller. However, the excessive use of emulsifying agents will inevitably lead to an increase in product costs, while the amount of emulsifying agents is too large, will also adversely affect the performance of coating applications, therefore, according to the storage period requirements of product use, the amount of emulsified agents to 4.5% (monosome quality score) as the best.
2.2 Effect of the amount of trigger on the average molecular weight and granularity of emulsion
fixed experimental conditions: ester acid ratio of 1:1, reaction temperature seed polymerization (45 x 2) degrees C, nuclear shell polymerization temperature (78 x 2) degrees C C, emulsifier dosage 4.5% (in mixed monosome), crosslinking dose 0.01% (in mixed monosome), drop plus time 2h, trigger dosage on the average molecular weight of emulsion and the law of changes in emulsion granularity can be seen in Table 2.From Table 2, it can be seen that the increase in the amount of trigger agent, emulsion granularity and the average molecular weight of emulsion showed a downward trend, but when the amount of trigger exceeded 0.35% of the mass of the monomer, the polymerization process is very easy to cause aggregation, the experiment can not be carried out normally. The addition of the trigger agent is the key to emulsion polymerization, the free-forming agent promotes the polymerization reaction continuously, the amount of the trigger agent increases, so that the number of free-forming agents in the system increases, the number of cores produced by the polymerization reaction will increase, because the short chain polymerization needs less energy, therefore, the chain reaction of the polymer will produce more short-chain molecules, so that the polymer molecular weight is reduced. At the same time, the increase of polymer core, the particle size of a single polymer molecule correspondingly reduced, similar to crystallization formation theory. From the requirements of 12000 to 15000 molecular weight of thickener for copper plate paper coatings, the amount of trigger agent 0.2% (in the fraction of mixed monolith mass) is the best.
2.3 Effect of reaction temperature on emulsion performance and free monosome content
Fixed experimental conditions: ester acid ratio 1:1, emulsifying agent dosage 4.5% (in mixed monosome), trigger dosage 0.1 2% (in mixed monosomes), 0.01% in crosslinking agents (in mixed monosomes), drop-plus time of 2h, seed polymerization temperature and nuclear shell polymerization temperature on the average molecular weight of emulsion and the law of changes in emulsion granularity can be seen in Table 3.
the fixed nuclear shell polymerization temperature (80 to 2) degrees C unchanged, the effect of changing the seed polymerization temperature on emulsion can be seen in Table 3.the fixed seed polymerization temperature (45 x 2) degrees C unchanged, the effect of changing the nuclear shell polymerization temperature on emulsion can be seen in Table 4.As can be seen from Tables 3 and 4, the seed polymerization and nuclear shell polymerization stage, with the increase of temperature, the granularity of the emulsion gradually decreases, and the content of the monosome in the emulsion decreases, but when the temperature rises to a certain stage, the particle size of the free monosome and the size of the emulsion does not change significantly. This is because as the temperature increases, enough energy is provided, the speed and number of free fundamentals released by the trigger increases accordingly, the nuclei produced by the polymerization reaction increase, the short-chain molecules produced by the polymerization reaction increase, and the lotion granularity decreases. At the same time, the increase of temperature also causes the polymerization reaction to be carried out more thoroughly, and the free monosome without the polymerization reaction decreases. According to the requirements of product use, from the point of view of saving energy consumption, the reaction temperature is determined to be the seed polymerization temperature (45 x 2) degrees C, and the nuclear shell polymerization reaction temperature is (80 to 2) degrees C as the optimal reaction temperature.
2.4 Effect of reaction time on emulsion granularity and free monosomes
Fixed experimental conditions: ester acid ratio 1:1, emulsifier dosage 4.5% (in mixed monosome), trigger dosage 0.2% (in mixed monosome), cross-linking agent Dosing 0.01% (in mixed monosomes), reaction temperature seed polymerization (45 x 2) degrees C, nuclear shell polymerization temperature (78 x 2) degrees C, change the reaction time on the emulsion particle size and free monosomal content change law, the experimental results can be seen in Table 5.From Table 5, it can be seen that the reaction time has obvious effect on the granularity and free monomer content of the emulsion, the reaction time is too short, the single body and the trigger drop acceleration is too fast, the reaction is prone to explosion, and with the extension of the reaction time, the granularity of the emulsion is gradually reduced, and the content of the free monomer is gradually reduced. Starting from the actual use requirements, determine the reaction time 3h is the best.3 Conclusion
(1) With ethyl acrylic and methyl acrylic as raw materials, a 25% acrylic co-polylacement with an average molecular weight of 12,000 to 15000 was prepared by seed polymerization method.
(2) The average molecular weight and emulsion granularity of acrylic-based water-based coating thickeners and storage stability are significantly affected by emulsifying agent dosage, trigger dosage, reaction temperature and reaction time. (single mass fraction), the amount of trigger is 0.2% (in the fraction of mixed monosome mass), the seed polymerization temperature is (45 x 2) degrees C, the nuclear shell polymerization reaction temperature is (80 x 2) degrees C, the reaction time is 3h is the best.
(3) the experimental optimal conditions of acrylic-based water-based coating thickener monosome content is low, environmental protection, safety, storage stability far exceeds the traditional method of preparation of products..