A high-permeability coating emulsion and a method for preparing the same

Abstract

This invention discloses a high-transparency topcoat emulsion and its preparation method, belonging to the field of polymer coating technology. The method includes the following steps: (1) adding hard monomers, soft monomers, functional monomers, and 60-70% reactive emulsifier to deionized water, performing high-speed shear pre-emulsification to obtain a pre-emulsion; (2) adding the remaining reactive emulsifier, deionized water, and pH buffer to a reaction vessel, heating to 80°C under nitrogen protection, adding 10% pre-emulsion and 1 / 3 initiator, and maintaining the temperature for 30 minutes to obtain a seed emulsion; (3) simultaneously adding the remaining pre-emulsion and remaining initiator to the seed emulsion at 80°C for 3 hours, heating to 85°C, maintaining the temperature for 1 hour, cooling to 60°C, adding a crosslinking agent, and reacting for 0.5 hours; (4) after the reaction, cooling to 40°C, adding a neutralizing agent to adjust the pH to 8.0-8.5, and filtering the material. The emulsion of this invention has high water permeability, high transparency and strong weather resistance, while meeting environmental protection requirements and is suitable for high-performance application scenarios.

Description

Technical Field

[0001] This invention relates to the field of polymer material synthesis technology, specifically to a high-permeability surface emulsion and its preparation method. Background Technology

[0002] Acrylic emulsions are widely used in industrial coatings, architectural coatings, and packaging materials due to their excellent film-forming properties, weather resistance, and environmental friendliness. However, traditional acrylic emulsions suffer from problems such as poor water vapor permeability, insufficient transparency, limited weather resistance, and environmental defects. These issues can lead to the inability of moisture to escape from the substrate, causing blistering and peeling, affecting the display of natural textures on substrates such as stone and wood grain, yellowing under ultraviolet radiation, reducing decorative durability, and the presence of organic solvents in some products, which do not meet green building material standards, thus hindering their application in high-end transparent coatings.

[0003] In existing technologies, permeability is typically improved by adding hydrophilic monomers, but this often sacrifices water resistance. Alternatively, silicone-acrylic modification can be used to improve weather resistance, but this is costly and results in insufficient permeability. Summary of the Invention

[0004] To overcome the aforementioned technical problems in the existing technology, the present invention provides a water vapor permeability ≥1.5g / m³. 2 A high-transparency topcoat emulsion with a transmittance of ≥95% (film thickness 50μm), water resistance (no white marks after 168h immersion) and zero VOCs, and its preparation method.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0006] In one aspect, this invention provides a method for preparing a high-transparency overlay emulsion, comprising the following steps:

[0007] (1) Hard monomers, soft monomers, functional monomers and 60-70% reactive emulsifier are added to deionized water and pre-emulsified by high-speed shearing to obtain a pre-emulsion.

[0008] (2) Add the remaining reactive emulsifier, deionized water and pH buffer to the reactor, heat to 80°C under nitrogen protection, add 10% pre-emulsion and 1 / 3 to 1 / 2 initiator, keep warm for 30 min to obtain seed emulsion;

[0009] (3) At 80°C, the remaining pre-emulsion and the remaining initiator are added dropwise to the seed emulsion simultaneously for 3 hours. The temperature is raised to 85°C, kept warm for 1 hour, cooled to 60°C, and crosslinking agent is added. The reaction is carried out for 0.5 hours.

[0010] (4) After the reaction is complete, cool down to 40°C, add a neutralizing agent to adjust the pH to 8.0-8.5, and filter out the material.

[0011] As a further embodiment of the present invention, the weight fractions of each component are as follows: 30-50 parts of hard monomer, 40-60 parts of soft monomer, 2-8 parts of functional monomer, 1-3 parts of reactive emulsifier, 100-120 parts of deionized water, 0.3-0.8 parts of initiator, 1-4 parts of crosslinking agent, and 0.1-0.5 parts of pH buffer.

[0012] As a further embodiment of the present invention, the weight fractions of each component are as follows: 35-45 parts of hard monomer, 45-55 parts of soft monomer, 3-5 parts of functional monomer, 1.5-2 parts of reactive emulsifier, 105-115 parts of deionized water, 0.4-0.6 parts of initiator, 2-3 parts of crosslinking agent, and 0.2-0.3 parts of pH buffer.

[0013] As a further embodiment of the present invention: the hard monomer is at least one selected from methyl methacrylate, styrene, methyl acrylate, and n-butyl methacrylate;

[0014] And / or, the soft monomer is butyl acrylate and / or isooctyl acrylate;

[0015] And / or, the functional monomer is a mixture of hydroxyethyl acrylate and acrylic acid in a weight ratio of 3:1;

[0016] And / or, the pH buffer is sodium bicarbonate;

[0017] And / or, the initiator is a persulfate;

[0018] And / or, the crosslinking agent is ethyl acetoacetate methacrylate;

[0019] And / or, the neutralizing agent is ammonia.

[0020] As a further embodiment of the present invention: the hard monomer is methyl methacrylate;

[0021] And / or, the soft monomer is butyl acrylate and isooctyl acrylate.

[0022] As a further aspect of the present invention: in step (1), the shearing speed is 3000 rpm and the shearing time is 15 min.

[0023] As a further embodiment of the present invention: in steps (2) and (3), the initiator is added in the form of an aqueous solution.

[0024] In a second aspect, the present invention provides a high-permeability cover emulsion, which is prepared by the above-described method for preparing a high-permeability cover emulsion.

[0025] The beneficial effects of this invention are as follows:

[0026] This invention employs a "core-shell-channel" structural design. The core layer, composed of a methyl methacrylate / butyl acrylate copolymer, provides a rigid framework. The shell layer, enriched with functional monomers, forms hydrophilic microdomains, enhancing adhesion while constructing permeable channels. The channel portion utilizes a molecular-level hydrogen bond network formed by hydroxyethyl acrylate and acrylic acid to construct water vapor diffusion pathways. Furthermore, this invention effectively avoids explosive polymerization through a gradient temperature control process, ensuring uniform emulsion particle size (D50≈80nm, PDI<0.1), significantly improving product stability. The resulting acrylic emulsion possesses high permeability, high transparency, and strong weather resistance, while also meeting environmental protection requirements, making it suitable for high-performance applications. Detailed Implementation

[0027] The present invention is further illustrated below by way of examples, but these examples do not limit the invention to the scope of the embodiments described. Experimental methods in the following examples, unless otherwise specified, were performed according to conventional methods and conditions, or as selected in the product instructions. Furthermore, all reagents and raw materials used in this invention are commercially available.

[0028] Example 1

[0029] (1) Preparation of materials for the single bottle: Mix 50 parts of butyl acrylate, methyl methacrylate, hydroxyethyl acrylate, acrylic acid, BLJ-3025 and deionized water at 3000 rpm for 15 min.

[0030] (2) Preparation of materials for reaction flask: deionized water, BLJ-3025, sodium bicarbonate;

[0031] (3) Seed reaction: Nitrogen gas was introduced into the reaction flask and the temperature was raised to 80°C. 10% of (1) was taken and added to the initial initiator. The temperature was maintained for 30 minutes.

[0032] (4) Gradient temperature controlled polymerization:

[0033] In the first stage, the remaining pre-emulsion was added dropwise at 80°C (3 hours), while potassium persulfate aqueous solution was added dropwise simultaneously.

[0034] Phase 2: Heat to 85℃ and hold for 1 hour;

[0035] In the third stage, the temperature was lowered to 60°C, a crosslinking agent was added, and the reaction was allowed to proceed for 0.5 hours.

[0036] (5) Cool down to 40°C, add a neutralizing agent to adjust the pH to 8.0-8.5, and filter out the material.

[0037] Example 2

[0038] (1) Preparation of materials for the single bottle: Mix 50 parts of butyl acrylate, methyl methacrylate, hydroxyethyl acrylate, acrylic acid, BLJ-3025 and deionized water at 3000 rpm for 15 min.

[0039] (2) Preparation of materials for reaction flask: deionized water, BLJ-3025, sodium bicarbonate;

[0040] (3) Seed reaction: Nitrogen gas was introduced into the reaction flask and the temperature was raised to 80°C. 10% of (1) was taken and added to the initial initiator. The temperature was maintained for 30 minutes.

[0041] (4) Gradient temperature controlled polymerization:

[0042] In the first stage, the remaining pre-emulsion was added dropwise at 80°C (3 hours), while potassium persulfate aqueous solution was added dropwise simultaneously.

[0043] Phase 2: Heat to 85℃ and hold for 1 hour;

[0044] In the third stage, the temperature was lowered to 60°C, a crosslinking agent was added, and the reaction was allowed to proceed for 0.5 hours.

[0045] (5) Cool down to 40°C, add a neutralizing agent to adjust the pH to 8.0-8.5, and filter out the material.

[0046] Example 3

[0047] (1) Preparation of materials for the single bottle: Mix 50 parts of butyl acrylate, methyl methacrylate, hydroxyethyl acrylate, acrylic acid, BLJ-3025 and deionized water at 3000 rpm for 15 min.

[0048] (2) Preparation of materials for reaction flask: deionized water, BLJ-3025, sodium bicarbonate;

[0049] (3) Seed reaction: Nitrogen gas was introduced into the reaction flask and the temperature was raised to 80°C. 10% of (1) was taken and added to the initial initiator. The temperature was maintained for 30 minutes.

[0050] (4) Gradient temperature controlled polymerization:

[0051] In the first stage, the remaining pre-emulsion was added dropwise at 80°C (3 hours), while potassium persulfate aqueous solution was added dropwise simultaneously.

[0052] Phase 2: Heat to 85℃ and hold for 1 hour;

[0053] In the third stage, the temperature was lowered to 60°C, a crosslinking agent was added, and the reaction was allowed to proceed for 0.5 hours.

[0054] (5) Cool down to 40°C, add a neutralizing agent to adjust the pH to 8.0-8.5, and filter out the material.

[0055] The steps of Examples 1 to 3 are as shown in Table 1 below.

[0056] Table 1. Specific formulations and components of raw materials used in Examples 1-3 (unit: g)

[0057]

[0058] The present invention also provides the following comparative examples.

[0059] Comparative Example 1

[0060] Referring to Example 1, commercially available EPA073 (Clariant) was used, which is a non-reactive emulsifier, and all other aspects were the same as in Example 1.

[0061] Comparative Example 2

[0062] Referring to Example 1, hydroxyethyl acrylate was not added, but everything else was the same as in Example 1.

[0063] Comparative Example 3

[0064] Referring to Example 1, acrylic acid was replaced with methacrylic acid, and everything else was the same as in Example 1.

[0065] Comparative Example 4

[0066] Referring to Example 1, the crosslinking agent was added in the early stage of monomer bottle raw material preparation, and the rest was the same as in Example 1.

[0067] Comparative Example 5

[0068] Referring to Example 1, no crosslinking agent was added, and everything else was the same as in Example 1.

[0069] Effect Example

[0070] The emulsions obtained in the examples and comparative examples were tested using the following methods:

[0071] I. Water permeability test: The test shall be conducted in accordance with ASTM E96.

[0072] II. Light transmittance test: The test shall be conducted in accordance with GB / T 9755.

[0073] III. Water resistance: Tested according to ISO 2812-3.

[0074] IV. UV resistance: Tested according to GB / T 23987.

[0075] The products obtained in Examples 1-3 and Comparative Examples 1-5 were subjected to performance tests. The specific test results are shown in Tables 2 and 3.

[0076] Table 2

[0077] Water permeability and air permeability <![CDATA[1.82g / m 2 ·h]]> <![CDATA[1.7g / m 2 ·h]]> <![CDATA[1.9g / m 2 ·h]]> Light transmittance (50μm film) 96.3％ 97.4％ 96％ Water resistance (168h) No white marks, no peeling No white marks, no peeling No white marks, no peeling UV resistant (1000h) ΔE < 0.5 (no yellowing) ΔE < 0.5 (no yellowing) ΔE < 0.5 (no yellowing)

[0078] Table 3

[0079]

[0080]

[0081] As shown in Table 2, the high-transparency cover emulsion obtained in the embodiments of the present invention has excellent water and air permeability, light transmittance, water resistance, and UV resistance.

[0082] As shown in Table 3, the emulsion obtained in the comparative example was not as effective as that in the example, and all performance tests showed varying degrees of inadequacy.

[0083] Application Examples

[0084] Application 1: Building exterior wall cladding

[0085] The emulsion was diluted to a solid content of 20% and sprayed onto the stone paint coating (0.2 kg / m2). After drying, a transparent protective film was formed, which increased the water vapor permeability of the substrate by 40%. No corrosion was observed in the salt spray test (ASTM B117) for 720 hours.

[0086] Application 2: Waterproofing of wooden building materials

[0087] Apply to oak flooring (2 coats, consumption 0.15kg / m2), water absorption rate ≤5% after 168h, while maintaining the clarity of wood grain (haze value <5%).

[0088] Finally, it should be noted that in this invention, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus.

[0089] Although this disclosure has been described above through specific embodiments, it should be understood that those skilled in the art can devise various modifications, improvements, or equivalents to this disclosure within the spirit and scope of the appended solutions. Such modifications, improvements, or equivalents should also be considered to be included within the scope of protection claimed in this disclosure.

Claims

1. A method for preparing a high-transparency topcoat emulsion, characterized in that, Includes the following steps: (1) Hard monomer, soft monomer, functional monomer and 60-70% reactive emulsifier are added to deionized water and pre-emulsified by high-speed shearing to obtain a pre-emulsion; the hard monomer is methyl methacrylate; the soft monomer is butyl acrylate and / or isooctyl acrylate; the functional monomer is a mixture of hydroxyethyl acrylate and acrylic acid in a weight ratio of 3:

1. (2) Add the remaining reactive emulsifier, deionized water and pH buffer to the reactor, heat to 80°C under nitrogen protection, add 10% pre-emulsion and 1 / 3 to 1 / 2 initiator, keep warm for 30 min to obtain seed emulsion; (3) At 80°C, the remaining pre-emulsion and the remaining initiator are added dropwise to the seed emulsion simultaneously for 3 hours. The temperature is raised to 85°C, kept warm for 1 hour, cooled to 60°C, and a crosslinking agent is added. The reaction is carried out for 0.5 hours. The crosslinking agent is ethyl acetoacetate methacrylate. (4) After the reaction is complete, cool down to 40°C, add a neutralizing agent to adjust the pH to 8.0~8.5, and filter out the material; The weight fractions of each component are as follows: 30-50 parts hard monomer, 40-60 parts soft monomer, 2-8 parts functional monomer, 1-3 parts reactive emulsifier, 100-120 parts deionized water, 0.3-0.8 parts initiator, 1-4 parts crosslinking agent, and 0.1-0.5 parts pH buffer.

2. The method for preparing the high-transparency topcoat emulsion according to claim 1, characterized in that, The weight fractions of each component are as follows: 35-45 parts hard monomer, 45-55 parts soft monomer, 3-5 parts functional monomer, 1.5-2 parts reactive emulsifier, 105-115 parts deionized water, 0.4-0.6 parts initiator, 2-3 parts crosslinking agent, and 0.2-0.3 parts pH buffer.

3. The method for preparing the high-transparency topcoat emulsion according to claim 1, characterized in that, The pH buffer is sodium bicarbonate; And / or, the initiator is a persulfate; And / or, the neutralizing agent is ammonia.

4. The method for preparing the high-transparency topcoat emulsion according to claim 1, characterized in that, The soft monomers are butyl acrylate and isooctyl acrylate.

5. The method for preparing the high-transparency topcoat emulsion according to claim 1, characterized in that, In step (1), the shearing speed is 3000 rpm and the shearing time is 15 min.

6. The method for preparing the high-transparency topcoat emulsion according to claim 1, characterized in that, In steps (2) and (3), the initiator is added in the form of an aqueous solution.

7. A high-transparency topcoat emulsion, which is prepared by the method of preparing the high-transparency topcoat emulsion according to any one of claims 1 to 6.

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