Technical Field
The invention relates to the field of coatings, in particular to a styrene-acrylic emulsion, a preparation method and application thereof, and a latex paint coating.
Background
Compared with non-aqueous paint, the styrene-acrylic emulsion paint has the advantages of low toxicity, difficult combustion, low price, rinse resistance, good acid and alkali resistance, high bonding strength, tough film and the like, and is very suitable for being used as indoor paint.
However, the emulsion polymerization stability of the traditional styrene-acrylic emulsion coating is poor, and the viscosity is low, so that a styrene-acrylic emulsion with high emulsion polymerization stability and proper viscosity is needed.
Disclosure of Invention
Therefore, it is necessary to provide a styrene-acrylic emulsion with improved emulsion polymerization stability and proper viscosity, a preparation method and application thereof, and a latex paint, aiming at the problems of poor emulsion polymerization stability and low viscosity of the traditional styrene-acrylic emulsion paint.
The styrene-acrylic emulsion comprises the following raw material components in percentage by mass:
wherein the pH value of the styrene-acrylic emulsion is 6.5-7.5.
The styrene-acrylic emulsion has reasonable component proportion, namely, the raw material components such as an initiator, an emulsifier and the like are added on the basis of butyl acrylate, styrene and acrylic acid to synthesize the polymerized emulsion. Specifically, the components of the styrene-acrylic emulsion are reasonable in proportion, and the addition of the initiator can control the fineness and uniformity of latex particles of the prepared styrene-acrylic emulsion; the addition of the functional monomer acrylic acid can ensure that all components in a styrene-acrylic emulsion system are properly crosslinked, and emulsion particles can be well distributed in a water phase, so that the viscosity of the styrene-acrylic emulsion is proper; the introduction of the emulsifier can form a hydration layer on the surface of the latex particles, so that the steric hindrance effect is generated among the latex particles, and experiments prove that the reasonable proportion of the components can comprehensively improve the polymerization stability of the styrene-acrylic emulsion.
In one embodiment, the emulsifier is selected from at least one of polyoxyethylene octyl phenol ether-10 and sodium lauryl sulfate.
In one embodiment, the emulsifier is a composite emulsifier composed of polyoxyethylene octyl phenol ether-10 and sodium dodecyl sulfate, and the mass ratio of the sodium dodecyl sulfate to the polyoxyethylene octyl phenol ether-10 is (1:2) - (3: 1).
In one embodiment, the initiator is selected from at least one of persulfates and hydroperoxides.
The invention also provides a preparation method of the styrene-acrylic emulsion, which comprises the following steps:
preparing raw materials according to the proportion of each raw material component of the styrene-acrylic emulsion;
mixing butyl acrylate, styrene, acrylic acid, a part of emulsifier and a part of water, and standing to obtain a pre-emulsion;
mixing a part of the pre-emulsion, the rest of the emulsifier and the rest of the water to obtain a mixed solution, heating the mixed solution until the mixed solution is blue, and adding the rest of the pre-emulsion and the initiator;
heating and preserving heat, cooling and then adjusting the pH value to 6.5-7.5 to obtain the styrene-acrylic emulsion.
In one embodiment, in the step of mixing butyl acrylate, styrene, acrylic acid, a part of the emulsifier and a part of the water, butyl acrylate, styrene, acrylic acid, 1/3-1/2 parts by mass of the total emulsifier and 1/3-1/2 parts by mass of the total water are mixed.
In one embodiment, in the step of mixing a part of the pre-emulsion, the remaining emulsifier and the remaining water to obtain the mixed solution, 1/4 to 1/3 parts by mass of the pre-emulsion, the remaining emulsifier and the remaining water, based on the total pre-emulsion, are mixed to obtain the mixed solution.
In addition, the invention also provides an application of the styrene-acrylic emulsion or the styrene-acrylic emulsion prepared by the preparation method of the styrene-acrylic emulsion in preparing the coating.
In addition, the invention also provides an application of the styrene-acrylic emulsion or the styrene-acrylic emulsion prepared by the preparation method of the styrene-acrylic emulsion in preparing latex paint.
The invention also provides a latex paint which comprises the styrene-acrylic emulsion or the styrene-acrylic emulsion prepared by the preparation method of the styrene-acrylic emulsion.
Drawings
FIG. 1 is an infrared spectrum of a styrene-acrylic emulsion in example 1 of the present invention.
FIG. 2 is an infrared spectrum of styrene in example 1 of the present invention.
FIG. 3 is an infrared spectrum of butyl acrylate in example 1 of the present invention.
Detailed Description
In order to make the aforementioned objects, features and advantages of the present invention comprehensible, embodiments accompanied with figures are described in detail below. In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present invention. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein.
Unless defined otherwise, all 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 belongs. The terminology used in the description of the invention herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, the term "and/or" includes any and all combinations of one or more of the associated listed items.
The embodiment of the invention provides styrene-acrylic emulsion which comprises the following raw material components in percentage by mass:
wherein the pH value of the styrene-acrylic emulsion is 6.5-7.5.
In one embodiment, the emulsifier is selected from at least one of polyoxyethylene octylphenol ether-10 (OP-10) and Sodium Dodecyl Sulfate (SDS). Further, the emulsifier is a composite emulsifier composed of polyoxyethylene octyl phenol ether-10 and sodium dodecyl sulfate, and further, the mass ratio of the sodium dodecyl sulfate to the polyoxyethylene octyl phenol ether-10 is (1:2) - (3: 1). Wherein, sodium dodecyl sulfate is a negative ion emulsifier, which is attached to the surface of the emulsion particles to generate electrostatic repulsion force to avoid the reaction between the emulsion particles, and polyoxyethylene octyl phenol ether-10 is a nonionic emulsifier, which is attached to the surface of the emulsion particles to form a hydration layer to generate steric hindrance effect to stabilize the emulsion particles.
In one embodiment, the initiator is selected from at least one of persulfates and hydroperoxides. Further, the initiator is selected from potassium persulfate.
The styrene-acrylic emulsion has reasonable component proportion, namely, the raw material components such as an initiator, an emulsifier and the like are added on the basis of butyl acrylate, styrene and acrylic acid to synthesize the polymerized emulsion. Specifically, the components of the styrene-acrylic emulsion are reasonable in proportion, and the addition of the initiator can control the fineness and uniformity of latex particles of the prepared styrene-acrylic emulsion; the addition of the functional monomer acrylic acid can ensure that all components in a styrene-acrylic emulsion system are properly crosslinked, and emulsion particles can be well distributed in a water phase, so that the viscosity of the styrene-acrylic emulsion is proper; the introduction of the emulsifier can form a hydration layer on the surface of the emulsion particles, so that the emulsion particles generate a steric hindrance effect, and the reasonable proportion of the components can improve the polymerization stability of the styrene-acrylic emulsion.
The invention also provides a preparation method of the styrene-acrylic emulsion, which comprises the following steps:
s1, preparing raw material components of the styrene-acrylic emulsion according to any embodiment of the invention.
Specifically, the raw material components are prepared according to the following mass percentage:
among them, commercially available styrene, butyl acrylate and acrylic acid monomers contain a polymerization inhibitor in many cases to prevent self-polymerization, and purification of the monomers is required. Wherein, the polymerization inhibitor in the styrene and the acrylic acid is hydroquinone, which is removed by an alkali washing method, and the hydroquinone reacts with the sodium hydroxide to generate the sodium hydroquinone. The polymerization inhibitor of butyl acrylate is p-hydroxyanisole which is removed by sodium hydroxide solution with the concentration of 4-6%.
S2, mixing butyl acrylate, styrene, acrylic acid, a part of emulsifier and a part of water, and standing to obtain the pre-emulsion.
In one embodiment, butyl acrylate, styrene, acrylic acid, 1/3-1/2 parts by mass of total emulsifier and 1/3-1/2 parts by mass of total water are mixed.
S3, mixing a part of the pre-emulsion, the rest of the emulsifier and the rest of the water to obtain a mixed solution, heating the mixed solution until the mixed solution is blue, adding the rest of the pre-emulsion and the initiator, heating, preserving heat, cooling, and adjusting the pH value to 6.5-7.5 to obtain the styrene-acrylic emulsion.
In one embodiment, the pre-emulsion with the total pre-emulsion mass of 1/4-1/3, the remaining emulsifier and the remaining water are mixed to obtain a mixed solution.
In one embodiment, the pH is adjusted to 6.5-7.5 with ammonia.
The preparation method of the styrene-acrylic emulsion is simple, and the prepared styrene-acrylic emulsion is high in polymerization stability and proper in viscosity.
The invention also provides an application of the styrene-acrylic emulsion in any embodiment of the invention or the styrene-acrylic emulsion prepared by the preparation method of the styrene-acrylic emulsion in any embodiment of the invention in preparation of latex paint.
In one embodiment, the application of the styrene-acrylic emulsion in preparing the latex paint comprises the following steps:
v1, mixing water and sodium hydroxymethyl cellulose to obtain a mixed solution.
Wherein the mixing is realized by stirring, specifically, the stirring speed is 280r/min-320r/min, and the stirring time is 10min-20 min.
V2, adding a defoaming agent and a dispersing agent into the mixed solution, mixing, adding ethylene glycol butyl ether, and mixing.
Wherein, the mixing is also in a stirring and mixing mode, specifically, the stirring speed is 780r/min-850r/min, and the stirring time is 10min-20 min.
V3, adding the styrene-acrylic emulsion provided by any embodiment of the invention or the styrene-acrylic emulsion prepared by the preparation method of the styrene-acrylic emulsion provided by any embodiment of the invention, a leveling agent and talcum powder in a stirring state, uniformly mixing and discharging.
In this embodiment, the stirring speed is reduced to 280r/min-320r/min under the stirring state, and the stirring is more reasonable under the stirring speed. The monomer is dispersed into smaller monomer beads at an excessively high stirring speed, the surface area of the monomer beads is larger, the amount of the emulsifier adsorbed on the surfaces of the monomer beads is increased, the number of micelles in water is reduced, the nucleation probability of the micelles is reduced, and the number of the generated emulsion particles is reduced and the diameter of the emulsion particles is increased. That is, when the stirring speed is increased, the diameter of the latex particles is not decreased but increased. Such disadvantages are mainly twofold: on the one hand, the reduction of the number of emulsion particles can reduce the polymerization reaction rate; on the other hand, too high a stirring speed increases the amount of air mixed into the emulsion polymerization system, while oxygen in the air is a polymerization inhibitor for radical reaction, which decreases the polymerization rate, and further, if the stirring is too severe, the emulsion may be gelled or even broken.
Further, in the step of adding the styrene-acrylic emulsion, the leveling agent and the talcum powder, the styrene-acrylic emulsion and the talcum powder are added and mixed uniformly, and then the leveling agent is added. Further, after the styrene-acrylic emulsion and the talcum powder are added, stirring is carried out for 20min to 40min, then the flatting agent is added, and stirring is continued for 15min to 25 min. Therefore, the solid filler powder such as talcum powder and the like can be fully wetted, the powder is prevented from forming a wrapping pattern or blocking, and the defoaming agent and the flatting agent are added later to prevent adverse effects on coating of the coating due to air in gaps of the filler such as the powder and the like which is dissolved in the coating.
In one embodiment, the defoamer is selected from BYK-141 defoamers, which are solvent-based silicone defoamers.
In one embodiment, the dispersant is selected from BYK-AT203 dispersant, and the dispersant has wetting and dispersing functions, is a controllable flocculant and can generate thixotropy. Used for improving the wettability of the pigment and the filler and the stability of the filler.
In one embodiment, the leveling agent is selected from a BYK-358N leveling agent, belongs to a polyacrylic acid solution, and can improve the leveling property and the gloss, generate a long-wave effect, prevent shrinkage cavity and not influence the coating property and the interlayer adhesion.
The invention also provides a latex paint which comprises the styrene-acrylic emulsion or the styrene-acrylic emulsion prepared by the preparation method of the styrene-acrylic emulsion in any embodiment of the invention.
The emulsion paint has good stability and proper viscosity.
In order that the objects and advantages of the invention will be more clearly understood, the invention is further described in detail below with reference to examples. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.
Example 1
The preparation method of the styrene-acrylic emulsion comprises the following steps:
preparing a monomer pre-emulsion:
80g of distilled water was added to a three-necked flask equipped with a stirrer at a constant temperature, and 4g (3% equivalent) of a complex emulsifier was added thereto, wherein the mass ratio of SDS to OP-10 was 1: 1. Rapidly stirring for 20 min; adding 25g of styrene, 25g of butyl acrylate and 0.8g of acrylic acid in sequence, continuing stirring for 30min to emulsify uniformly to obtain milky monomer pre-emulsion, and taking out for later use.
Seed emulsion polymerization:
a four-neck flask provided with an electric stirrer, a spherical reflux condenser tube, a thermometer and a constant-pressure dropping funnel is placed in a constant-temperature water bath kettle, 20g of distilled water is added, the speed of the stirrer is adjusted to 350r/min, and the four-neck flask is rapidly stirred and gradually heated. 1.1g of the complex emulsifier was added to a bottle, and when the temperature rose to 80 ℃, 1/4 parts by mass of the monomer pre-emulsion and 0.13g of potassium persulfate solution were added, and a phenomenon was observed, which indicated the start of the emulsification reaction when a blue-light phenomenon occurred in the bottle and the reflux was reduced.
And then dripping the rest pre-emulsion and 0.37g of potassium persulfate solution within 2.5h, continuously reacting for 30min, heating to 85 ℃, preserving the temperature for 1h, cooling to room temperature, adjusting the pH value to 7.0 by using ammonia water, and discharging.
A preparation method of latex paint comprises the following steps:
firstly, 40ml of distilled water and 0.085g of hydroxymethyl cellulose are added into a three-necked bottle provided with a stirrer, the rotating speed of the stirrer is adjusted to 300r/min, 0.4g of BYK-AT203 dispersant is added after stirring and dissolving, stirring is carried out for 15 minutes, then 4g of ethylene glycol butyl ether is added, high-speed stirring is carried out AT the rotating speed of 800r/min, after uniform stirring is carried out, the rotating speed is reduced to 300r/min, slow stirring is continued, and 70g of styrene-acrylic emulsion (the solid content is 38%) in the embodiment, 70g of talcum powder, titanium dioxide powder (the proportion of the talcum powder and the titanium dioxide can be automatically adjusted according to whiteness) and a little color. Stirring for 0.5h, adding 0.2g of BYK-141 defoaming agent and 0.2g of BYK-358N flatting agent, stirring for 20min, and discharging to obtain the finished product.
Example 2
A method of preparing a styrene-acrylic emulsion, substantially the same as in example 1, except that: in the preparation of the monomer pre-emulsion, the amounts of styrene and butyl acrylate added were 20g and 30g, respectively.
Example 3
A method of preparing a styrene-acrylic emulsion, substantially the same as in example 1, except that: the mass of the composite emulsifier is 3g (2%).
Example 4
A method of preparing a latex paint coating substantially the same as in example 1, except that: after the stirring is uniform, the rotating speed is reduced to 250r/min, and then the stirring is continued slowly, so as to prepare the latex paint.
Comparative example 1
A method of preparing a styrene-acrylic emulsion, substantially the same as in example 1, except that: in the preparation of the monomer pre-emulsion, the amounts of styrene and butyl acrylate added were 35g and 15g, respectively.
Comparative example 2
A method of preparing a styrene-acrylic emulsion, substantially the same as in example 1, except that: during the preparation of the monomer pre-emulsion, the mass of the composite emulsifier was 8g (5%).
Comparative example 3
A method of preparing a latex paint coating substantially the same as in example 1, except that: after the stirring is uniform, the rotating speed is reduced to 150r/min, and then the stirring is continued slowly, so that the prepared emulsion paint has poor uniformity.
Comparative example 4
A method of preparing a latex paint coating substantially the same as in example 1, except that: after the mixture is stirred evenly, the rotating speed is reduced to 450r/min, and then the mixture is stirred slowly, the emulsion is stirred and exploded.
Comparative example 5
The preparation method of the styrene-acrylic emulsion comprises the following steps: the preparation method is substantially the same as that of example 1, except that: the initiator potassium persulfate was used in an amount of 1.28g (0.8% equivalent).
Comparative example 6
A method of preparing a styrene-acrylic emulsion, substantially the same as in example 1, except that: during the preparation of the monomer pre-emulsion, acrylic acid was added in an amount of 7 g.
Effect verification
The viscosity of the styrene-acrylic emulsion was measured using an NDJ-8S viscometer.
TABLE 1
As can be seen from Table 1, the styrene-acrylic emulsions prepared in the examples have moderate viscosity, uniform emulsion and good polymerization stability as compared with the comparative example. Among them, the styrene-acrylic emulsions in the groups of examples 1 and 2 are the most effective.
Furthermore, as can be seen from FIG. 1, 3448cm-1、2954cm-1is-CH3and-CH2Absorption peak of stretching vibration of 1723cm-1The peak is an expansion and contraction vibration absorption peak of C ═ O in the butyl acrylate group, and an expansion and contraction vibration absorption peak of C ═ O is also present in fig. 3. 1448cm-1Is a skeletal vibration absorption peak of a styrene benzene ring, which appears in FIGS. 1 to 3. 1171cm-1Is the symmetric stretching vibration absorption peak of C-O-C in butyl acrylate, which is also shown in FIG. 3, 694cm in FIG. 1-1Is a characteristic absorption peak of C-H out-of-plane bending in a benzene ring, 1600--1The range is the characteristic absorption peak region of the olefinic bond. 1650cm in the Infrared Spectrum 3 of butyl acrylate-1Is the absorption peak of C ═ C, and the infrared spectrum 2 of styrene is 1600-1800cm-1And an absorption peak appears, namely the absorption peak of C ═ C, while no absorption peak of C ═ C appears in the infrared spectrum 1 of the styrene-acrylic emulsion, and the C ═ C of the two monomers is broken under the action of the initiator. From the above analysis, it can be known that styrene and butyl acrylate monomers in the styrene-acrylic emulsion participate in the copolymerization reaction.
The technical features of the embodiments described above may be arbitrarily combined, and for the sake of brevity, all possible combinations of the technical features in the embodiments described above are not described, but should be considered as being within the scope of the present specification as long as there is no contradiction between the combinations of the technical features.
The above-mentioned embodiments only express several embodiments of the present invention, and the description thereof is more specific and detailed, but not construed as limiting the scope of the invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the inventive concept, which falls within the scope of the present invention. Therefore, the protection scope of the present patent shall be subject to the appended claims.
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