Aqueous polytetrafluoroethylene dispersion and its preparation method and application

Abstract

The present invention provides an aqueous polytetrafluoroethylene dispersion, a preparation method, and an application thereof. The aqueous polytetrafluoroethylene dispersion comprises polytetrafluoroethylene micropowder, water, a dispersant, a defoamer, a wetting agent, a thickener, and an antibacterial agent, wherein the dispersant is an acrylic block copolymer and the wetting agent is a Gemini silicone wetting agent. The aqueous polytetrafluoroethylene dispersion of the present invention has a small particle size and excellent stability, and does not exhibit phenomena such as creaming and stratification even during long-term storage. The aqueous polytetrafluoroethylene dispersion can be directly prepared by mixing polytetrafluoroethylene micropowder with water, a dispersant, a wetting agent, a defoamer, a thickener, and an antibacterial agent, and the preparation method is simple. The aqueous polytetrafluoroethylene dispersion can be used in a water-based coating to effectively improve the wear resistance of a coating made from the water-based coating.

Description

Technical Field

[0001] The invention relates to an aqueous polytetrafluoroethylene dispersion liquid and a preparation method and application thereof. Background Art

[0002] Polytetrafluoroethylene is a white fine powder, also known as PTFE wax. It has good mechanical properties, electrical properties, non-stickiness, lubricity, as well as excellent chemical resistance and weather resistance. It also has an extremely low coefficient of friction and a wide operating temperature range (-200 to 260°C), and has a large application market in water-based coatings.

[0003] Due to the strong hydrophobicity of polytetrafluoroethylene, it is difficult to add it directly to water-based coatings. Therefore, it is often necessary to prepare it into an aqueous dispersion before adding it. However, the aqueous dispersion prepared directly from polytetrafluoroethylene fine powder is unstable and easily stratified or paste-formed during storage, affecting the use effect. Summary of the Invention

[0004] The purpose of the present invention is to provide a storage-stable aqueous polytetrafluoroethylene dispersion and a preparation method and application thereof.

[0005] In order to achieve the above object, the technical solution adopted by the present invention is:

[0006] A water-based polytetrafluoroethylene dispersion comprises polytetrafluoroethylene powder, water, a dispersant, a defoaming agent, a wetting agent, a thickener and an antibacterial agent. The dispersant is an acrylic block copolymer, and the wetting agent is a Gemini organosilicon wetting agent.

[0007] The present invention avoids the problems of delamination, creaming, flocculation and the like by adding acrylic block copolymers, thereby ensuring the stability of the polytetrafluoroethylene dispersion. The general structural form of the acrylic block copolymers can be expressed as AB or ABC or ABA or (AB) n , for example, CARMOT DS-2130 dispersant from Aosjia. Furthermore, the synergistic effect of the acrylic block copolymer and the Gemini organosilicon wetting agent improves the long-term storage stability of the dispersion. Preferably, the Gemini organosilicon wetting agent is a polyether-modified organosilicon, for example, CARMOT CL-6001 wetting agent from Aosjia.

[0008] Preferably, the dispersant accounts for 0.5-5% of the total mass of the aqueous polytetrafluoroethylene dispersion, more preferably 0.5-3%, for example, 0.5%, 1.0%, 1.5%, 2.0%, 2.5%, 3%, etc.

[0009] Preferably, the wetting agent accounts for 0.5-2% of the total mass of the aqueous polytetrafluoroethylene dispersion, more preferably 0.8-1.5%, for example 0.8%, 0.9%, 1.0%, 1.1%, 1.2%, 1.3%, 1.4%, 1.5%.

[0010] Preferably, the thickener comprises one or more of associative polyurethane, polyamide wax, hydroxyethyl cellulose, acrylic polymer, polyurea, lignin sulfonate, silicate, silica powder, hydroxypropyl methylcellulose, and xanthan gum.

[0011] Preferably, the thickener accounts for 0.1 to 1% of the total mass of the aqueous polytetrafluoroethylene dispersion, and more preferably 0.1 to 0.5%.

[0012] In some embodiments, the thickener comprises associative polyurethane and / or hydroxypropyl methylcellulose.

[0013] Furthermore, the thickener is associative polyurethane and hydroxypropyl methylcellulose, and the mass ratio of the associative polyurethane to the hydroxypropyl methylcellulose is (1.5-2.5):1, for example, 1.5:1, 1.8:1, 2:1, 2.3:1 or 2.5:1.

[0014] Preferably, the defoaming agent includes one or more of an organosilicon defoaming agent, a mineral oil defoaming agent, a polymer defoaming agent, and a higher alcohol defoaming agent.

[0015] In some embodiments, the defoaming agent is an organosilicon defoaming agent, specifically a polysiloxane defoaming agent, such as Aosjia's CARMOT F-1301 defoaming agent.

[0016] Preferably, the defoaming agent accounts for 0.5-1.5% of the total mass of the aqueous polytetrafluoroethylene dispersion, for example, 0.5%, 0.8%, 1.0%, 1.3% or 1.5%.

[0017] Preferably, the antibacterial agent includes one or more of isothiazolinone, s-triazine, Bropol, ethylene glycol bis(hydroxymethyl) ether, zinc ion, and silver ion antibacterial agents.

[0018] In some embodiments, the antibacterial agent is an isothiazolinone antibacterial agent.

[0019] Preferably, the antibacterial agent accounts for 0.1-0.5% of the total mass of the aqueous polytetrafluoroethylene dispersion, for example, 0.1%, 0.2%, 0.3%, 0.4%, or 0.5%.

[0020] Preferably, based on the total mass of the aqueous polytetrafluoroethylene dispersion being 100%, the aqueous polytetrafluoroethylene dispersion comprises: 40-60% polytetrafluoroethylene powder,

[0021] Water 35-55%,

[0022] Dispersant 0.5~5%,

[0023] Defoaming agent 0.5~1.5%,

[0024] Wetting agent 0.5~2%,

[0025] Thickener 0.1~1%,

[0026] Antibacterial agent 0.1~0.5%.

[0027] Preferably, the aqueous polytetrafluoroethylene dispersion does not become creamy or stratified when stored at room temperature (25° C.) for 30 days, and the median particle size of the dispersed phase of the aqueous polytetrafluoroethylene dispersion is 3 to 6 μm.

[0028] A second object of the present invention is to provide a method for preparing the aqueous polytetrafluoroethylene dispersion as described above, the method comprising mixing polytetrafluoroethylene powder, water, a dispersant, a defoaming agent, a wetting agent, a thickener and an antibacterial agent, and then grinding and filtering.

[0029] Preferably, glass beads with a diameter of 0.5 to 2 mm are used for grinding.

[0030] Preferably, filtration is performed using a filter screen with 250 to 350 meshes.

[0031] The third object of the present invention is to provide a use of the aqueous polytetrafluoroethylene dispersion as described above, wherein the use comprises preparing a water-based coating using the aqueous polytetrafluoroethylene dispersion.

[0032] Preferably, the aqueous polytetrafluoroethylene dispersion accounts for 3-8% of the total mass of the aqueous coating, for example, 3%, 4%, 5%, 6%, 7%, 8%, or 9%.

[0033] Preferably, the water-based paint is a water-based silicone high-temperature paint.

[0034] Due to the application of the above technical solution, the present invention has the following advantages compared with the prior art:

[0035] The aqueous polytetrafluoroethylene dispersion of the present invention has a small particle size and excellent stability, and will not become creamy or delaminated even after long-term storage. The aqueous polytetrafluoroethylene dispersion can be directly prepared by mixing polytetrafluoroethylene micropowder with water, a dispersant, a wetting agent, a defoaming agent, a thickener, and an antibacterial agent, and the preparation method is simple. The aqueous polytetrafluoroethylene dispersion can be used in water-based coatings to effectively improve the wear resistance of the coating made from the water-based coating. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1These are photos of the wear resistance test of water-based silicone high-temperature coatings. The left picture is a control example, and the right picture is application example 1. DETAILED DESCRIPTION

[0037] The present invention is further described below with reference to the following examples. However, the present invention is not limited to the following examples. The implementation conditions used in the examples may be further adjusted according to the specific requirements of the application. Unspecified implementation conditions are conventional conditions in the industry. The technical features involved in the various embodiments of the present invention may be combined with each other as long as they do not conflict with each other.

[0038] The raw materials used in the following examples and comparative examples are all commercially available products, among which:

[0039] F1301, silicone defoamer, purchased from Jiangsu Aoshijia Material Technology Co., Ltd., product name CARMOT F-1301, polysiloxane, solid content 100%;

[0040] F2561, emulsion-type silicone defoamer, purchased from Jiangsu Aoshijia Material Technology Co., Ltd., solid content 22.5%;

[0041] CL-6001, a gemini silicone wetting agent, was purchased from Jiangsu Aoshijia Material Technology Co., Ltd., the product name is CARMOT CL-6001, solid content 100%;

[0042] UL-5124, silicone wetting agent, purchased from Jiangsu Aoshijia Material Technology Co., Ltd., product name is CARMOT UL-5124, solid content 100%;

[0043] DS-2130, acrylic block copolymer dispersant, purchased from Jiangsu Aoshijia Material Technology Co., Ltd., product name CARMOT DS-2130, solid content 40%;

[0044] NP5027, hydrophobically modified polyacrylate ammonium salt dispersant, San Nopco Co., Ltd.;

[0045] NP5040, polycarboxylate sodium salt dispersant, San Nopco Co., Ltd.;

[0046] BYK190, polymer dispersant, BYK Additives (Shanghai) Co., Ltd.

[0047] PTFE 236, polytetrafluoroethylene powder, purchased from Jiangxi Longhai Chemical Co., Ltd.

[0048] B10, isothiazolinone antimicrobial agent, purchased from Foshan Lanya Chemical;

[0049] Yaleshun RM-2020NPR, a nonionic polyurethane associative thickener, was purchased from The Dow Chemical Company;

[0050] HPMC, hydroxypropyl methylcellulose, was purchased from Shandong Chuangyao Biotechnology Co., Ltd.;

[0051] SHSILTM SH 9608-A, water-based silicone resin emulsion, Hubei Longsheng Sihai New Materials Co., Ltd.

[0052] 33802, glass powder, Foshan Caitian Industrial Materials Co., Ltd.;

[0053] D6600, adhesion promoter, Guangdong Yuehua Polymer New Materials Co., Ltd.;

[0054] 2062, anti-flash rust agent, Guangdong Yuehua Polymer New Materials Co., Ltd.;

[0055] C100MS, thickener, Opal Chemical.

[0056] A method for preparing an aqueous polytetrafluoroethylene dispersion comprises the following steps:

[0057] (1) Weigh the materials according to Table 1 below and set aside.

[0058] (2) Add PTFE 236, deionized water, dispersant, defoamer, wetting agent, thickener, and antibacterial agent into a mixing barrel in sequence, stir for 5 to 10 minutes, and add glass beads (Φ1.0 mm) and grind for 30 to 40 minutes.

[0059] (3) The mixture of step (2) was filtered through a 300-mesh nylon filter to obtain a uniform aqueous polytetrafluoroethylene dispersion.

[0060] Table 1

[0061]

[0062]

[0063] The aqueous polytetrafluoroethylene dispersions prepared in the above examples and comparative examples were subjected to particle size analysis and storage testing (stability observation at room temperature for 30 days). The results are shown in Table 2 below.

[0064] Paste definition: The slurry tends to clump during preparation or storage, no longer appears liquid and loses fluidity.

[0065] Definition of stratification: The slurry tends to separate out water during storage, and the degree of particle suspension decreases.

[0066] Table 2

[0067] D50 particle size Store at room temperature Example 1 5.4μm 30 days normal Example 2 4.7μm 30 days normal Example 3 3.8μm 30 days normal Example 4 4.3μm 30 days normal Example 5 4.9μm 30 days normal Comparative Example 1 9.3μm 7-day ointment Comparative Example 2 8.1μm 15 days of ointment Comparative Example 3 5.2μm 7-day stratification Comparative Example 4 7.9μm 1 day ointment

[0068] Application Example 1

[0069] A water-based organosilicon high-temperature coating, comprising the following materials in parts by weight:

[0070] Silicone resin emulsion, Sihai 9608A 50 parts;

[0071] Dispersant, DS-2130, 1.5 parts;

[0072] Glass powder, 33802, 15 parts;

[0073] Wetting agent, CARMOT UL-5124, 0.2 parts;

[0074] Defoamer, F2561, 0.2 parts;

[0075] Iron red paste (solid content 50%, main ingredient iron red pigment 130), 8 parts;

[0076] Adhesion promoter, D6600, 0.2 parts;

[0077] Anti-flash rust agent, 2062, 0.4 parts;

[0078] Thickener, C100MS, 0.3 parts;

[0079] 3.8 parts of the aqueous polytetrafluoroethylene dispersion prepared in Example 1.

[0080] The preparation method of the water-based organosilicon high-temperature coating refers to the existing technology, and the present invention does not make any specific restrictions.

[0081] Control Example

[0082] The difference from the above application example 1 is that no aqueous polytetrafluoroethylene dispersion is added.

[0083] Performance evaluation of the above water-based silicone high-temperature coatings:

[0084] Sandblast the laboratory steel plate, remove grease and then apply water-based silicone high-temperature coating, bake at 280℃ for 6 hours, and let it stand at room temperature for 12 hours to test the wear resistance. Wear resistance evaluation method: Use one corner of the laboratory steel plate (with a right angle) to scratch the coating on the sample and observe the degree of coating shedding and scratching. Figure 1 As shown, the left picture is a control example, in which the coating is scratched on the substrate; the right picture is application example 1, in which the addition of aqueous polytetrafluoroethylene dispersion significantly improves the wear resistance of the coating, and the coating also has excellent adhesion properties.

[0085] The above detailed description of the present invention is intended to enable persons familiar with the art to understand the contents of the present invention and implement them. It does not limit the scope of protection of the present invention. Any equivalent changes or modifications made based on the spirit of the present invention should be included in the scope of protection of the present invention.

Claims

1. An aqueous polytetrafluoroethylene dispersion, characterized in that: Taking the total mass of the aqueous polytetrafluoroethylene dispersion as 100%, the aqueous polytetrafluoroethylene dispersion comprises: 40-60% polytetrafluoroethylene powder, wherein the polytetrafluoroethylene powder is PTFE 236 type from Longhai Chemical; Water 35~55%; 0.5-5% of a dispersant, wherein the dispersant is an acrylic block copolymer dispersant, and the acrylic block copolymer dispersant is Aosjia CARMOT DS-2130 dispersant; 0.5-1.5% defoaming agent, wherein the defoaming agent is a silicone defoaming agent; 0.5-2% wetting agent, wherein the wetting agent is a Gemini organosilicon wetting agent, and the Gemini organosilicon wetting agent is Aosjia CARMOT CL-6001 wetting agent; 0.1-1% thickener, wherein the thickener is associative polyurethane and / or hydroxypropyl methylcellulose, and the associative polyurethane is Dow Aleson RM-2020NPR model; 0.1-0.5% of antibacterial agent, wherein the antibacterial agent is selected from one or more isothiazolinones.

2. The method for preparing an aqueous polytetrafluoroethylene dispersion as claimed in claim 1, wherein: The polytetrafluoroethylene powder, water, dispersant, defoamer, wetting agent, thickener and antibacterial agent are mixed and then ground and filtered.

3. The use of the aqueous polytetrafluoroethylene dispersion as claimed in claim 1, characterized in that: The application includes the use of aqueous polytetrafluoroethylene dispersions to prepare waterborne coatings.

4. The use according to claim 3, characterized in that: The aqueous polytetrafluoroethylene dispersion accounts for 3-8% of the total mass of the aqueous coating.

Images