Green high-foaming high-stone-chip-resistance coating as well as preparation method and application thereof

Abstract

The invention relates to a green high-foaming high-stone-chip-resistance coating as well as a preparation method and application thereof, and belongs to the field of high polymer materials. The stone chip resistant coating provided by the invention is prepared from the following components in parts by weight: 100 parts of PVC (Polyvinyl Chloride) resin, 35 to 50 parts of filler, 60 to 120 parts of aconite, 5 to 10 parts of adhesion promoter, 1 to 5 parts of moisture absorbent, 1 to 8 parts of stabilizer, 3 to 8 parts of foaming agent, 0.1 to 5 parts of thixotropic agent and 0 to 10 parts of polyacrylate. The stone-impact-resistant coating has good environmental protection property, stone-impact resistance, adhesiveness, cold resistance and water resistance, the aconitate plasticizer has good compatibility with PVC, the foaming rate of the foaming agent can be effectively increased, the specific gravity of the stone-impact-resistant coating is remarkably reduced, the weight is reduced by 5-6 kg, and the stone-impact-resistant coating is suitable for being used as a stone-impact-resistant coating material.

Description

Technical Field

[0001] The present invention relates to a stone impact resistant coating, a preparation method thereof and an application, belonging to the field of polymer materials. Background Art

[0002] During the driving process of an automobile, it is often subjected to impacts from gravel, sediment, unknown objects, or corrosion by water, moisture, ice, salt, acid rain, etc. This can easily damage the electrophoretic coating on the electrophoretic steel plate at the bottom of the automobile, thereby losing the protective effect on the steel plate and further affecting the service performance of the automobile. To avoid the above situation, a vehicle bottom coating with a thickness of 3 - 14 mm is usually sprayed on the bottom of the automobile to protect the vehicle body, so as to slow down the strong impact caused by the external environment on the vehicle bottom and improve the water resistance and corrosion resistance of the bottom plate. However, this will increase the weight of the automobile. As an emerging industry, new energy vehicles are the future development direction of the automotive industry. The battery is the core component of new energy vehicles, affecting the overall performance and safety of the vehicle. At present, the weight of the battery of new energy vehicles can reach more than 500 kg, resulting in a heavier weight of new energy vehicles. And the traditional vehicle bottom stone impact resistant coating will further increase the weight of new energy vehicles, greatly affecting the battery usage efficiency and the driving safety of the vehicle. Using a foaming vehicle bottom coating is an effective way to reduce the weight of new energy vehicles. However, the foaming vehicle bottom coating generally has problems such as low foaming rate and unstable foaming, resulting in an insignificant weight reduction of the vehicle bottom coating layer, or uneven holes inside, making the vehicle bottom coating more prone to damage when subjected to external forces and unable to play a role in protecting the vehicle bottom plate and the battery.

[0003] In addition, the stone impact resistant coating also has the following deficiencies. First, most of the vehicle bottom stone impact resistant coatings will add plasticizers to optimize the performance of the PVC stone impact resistant coating. However, there are certain problems with different types of plasticizers. For example, phthalate plasticizers are highly toxic and will cause irreversible effects on human health after long-term use; although plasticizers such as epoxidized soybean oil are non-toxic, their plasticizing effect on PVC is poor, and the foaming rate of the foaming agent is also relatively low when used in combination with the foaming agent; the citric acid ester plasticizer, which also has non-toxic and environmental protection properties, has a good plasticizing effect, but the hydroxyl group in its structure is extremely easy to absorb water, affecting the water resistance and stone impact resistance of the stone impact resistant coating. Second, although plasticizers such as cold-resistant DOA (dioctyl adipate) and DOS (dioctyl sebacate) used in new energy vehicles can improve the cold resistance of the stone impact resistant coating layer, the migration resistance of these plasticizers is generally average, and the plasticizer is relatively easy to migrate out. Therefore, the adhesion of the obtained stone impact resistant coating will be affected.

[0004] Chinese patent application CN117844314A discloses an anti-stone chip coating, preparation method and application for new energy battery shells. This technology uses matte PVC resin, PVC paste resin and PVC blended resin to make the anti-stone chip coating formed by the anti-stone chip coating have an anti-collision matte effect; at the same time, microsphere foaming agents of different particle sizes are used to cooperate with the matte PVC resin to improve the anti-scratch ability of the anti-stone chip coating. Chinese patent application CN109749534A discloses automotive PVC anti-stone chip coating and its preparation method, using 10-20% by weight of polyvinyl chloride paste resin and 0.1-5% of heat-expandable microspheres, and limiting the heat-expandable microspheres to unexpanded heat-expandable microspheres, expanded heat-expandable microspheres or a mixture of the two. The dense structure of the expanded microspheres allows them to be integrated with the high-resistance matrix, thereby producing good protection and improving the wear resistance and corrosion resistance of the coating. However, none of these prior arts solves the above technical problems.

[0005] Based on the above problems existing in the anti-stone impact coating in the prior art, it is necessary to develop an anti-stone impact coating with high foaming rate, high resistance to stone impact damage, green and harmless, suitable for long-term use, and able to ensure the normal driving of new energy vehicles in extremely cold weather or rainy weather. Summary of the invention

[0006] In order to solve the above problems, the present invention provides a green high-foaming and high-stone-impact resistance coating and a preparation method thereof. The stone-impact resistance coating has high foaming, low specific gravity, high stone-impact resistance and green environmental protection. It is also cold-resistant and water-resistant, and can enable new energy vehicles to run normally in cold or rainy weather. The processing method of the stone-impact resistance coating is convenient and simple to operate, and is suitable for large-scale industrial production.

[0007] The first aspect of the present invention provides a green high-foaming and high-stone-impact resistance coating, which comprises the following components by weight: 100 parts of PVC resin, 35-50 parts of filler, 60-120 parts of aconitate, 5-10 parts of adhesion promoter, 1-5 parts of hygroscopic agent, 1-8 parts of stabilizer, 3-8 parts of foaming agent, 0.1-5 parts of thixotropic agent and 0-10 parts of polyacrylate.

[0008] Optionally, the PVC resin is a PVC paste resin having a degree of polymerization of 1000 to 1200.

[0009] Optionally, the carbon number of the ester group of the aconitate is 4-8.

[0010] Optionally, the molecular weight of the aconitate is 340-510 g / mol.

[0011] Optionally, the aconitate is selected from one or more of tributyl aconitate, tripentyl aconitate, trihexyl aconitate, triheptyl aconitate, trioctyl aconitate, tris(2-ethylhexyl) aconitate; further optionally, the aconitate is selected from one or more of tributyl aconitate, trihexyl aconitate, trioctyl aconitate.

[0012] Experiments have found that when the selected aconitate has a molecular weight of 340-510 g / mol and is selected from tributyl aconitate, tripentyl aconitate, trihexyl aconitate, triheptyl aconitate, trioctyl aconitate, tris(2-ethylhexyl) aconitate, it can improve the stone impact resistance, adhesion and cold resistance of the coating. The reason is that when the number of ester group carbons of the aconitate ≤ 8, the molecular weight is relatively low and the ester group chain is relatively short, which can be effectively compatible with PVC. The better the compatibility, the higher the plasticizing efficiency and the better the cold resistance of the stone impact resistant coating; in addition, good compatibility is also beneficial to improving the foaming rate of the foaming agent, thereby realizing the weight reduction of the stone impact resistant coating.

[0013] Secondly, when the number of ester group carbons of the aconitate ≥ 4, compared with the aconitate with the number of ester group carbons < 4, the molecular weight is larger, and the ester group chain of the plasticizer has a certain length, so the aconitate is difficult to migrate and volatilize to the outside, and the adhesion performance of the stone impact resistant coating layer is better.

[0014] Optionally, the filler is one or more of calcium carbonate, nano calcium carbonate, graphene, kaolin, diatomite.

[0015] Optionally, the adhesion promoter is one or more of epoxy resin, polyamide resin, polyurethane resin.

[0016] Optionally, the moisture absorbent is calcium oxide.

[0017] Optionally, the stabilizer is one or more of mercaptomethyltin, zinc oxide, zinc stearate, aluminum stearate, potassium stearate, calcium zinc stabilizer.

[0018] Optionally, the foaming agent is a polyurethane foaming agent.

[0019] The selected aconitate plasticizer can be effectively compatible with PVC. The high compatibility can promote the stable foaming of the foaming agent, achieve a high foaming rate and uniform foaming of the foaming agent, and significantly reduce the weight of the coating layer.

[0020] Optionally, the thixotropic agent is one or more of LBCB-1 thixotropic lubricant, silica, organic bentonite.

[0021] Optionally, the polyacrylate is selected from one or more of n-butyl polyacrylate, n-pentyl polyacrylate, n-hexyl polyacrylate, n-heptyl polyacrylate, n-octyl polyacrylate, isooctyl polyacrylate.

[0022] In the second aspect of the present invention, a method for preparing the above-mentioned green high-foaming and high-stone-chip-resistant coating is provided. The preparation steps of the stone-chip-resistant coating include:

[0023] (1) Heat and stir the PVC resin. When the temperature reaches 75 - 90 °C, add the filler, aconitate ester, and adhesion promoter according to the formulation ratio, and stir and mix evenly;

[0024] (2) Add the moisture absorbent, stabilizer, and thixotropic agent according to the formulation ratio, continue to stir until evenly mixed, discharge and cool down to room temperature;

[0025] (3) Mix the product obtained in step (2) with the foaming agent according to the formulation ratio, and stir at room temperature for 1 - 5 h to obtain the stone-chip-resistant coating.

[0026] Optionally, the preparation steps of the stone-chip-resistant coating include:

[0027] (1) Heat and stir the PVC resin. When the temperature reaches 80 °C, add the filler, plasticizer, and adhesion promoter according to the formulation ratio, and stir and mix evenly;

[0028] (2) Add the moisture absorbent, stabilizer, and thixotropic agent according to the formulation ratio, continue to stir until evenly mixed, discharge and cool down to room temperature;

[0029] (3) Mix the product obtained in step (2) with the foaming agent according to the formulation ratio, and stir at room temperature for 3 h to obtain the stone-chip-resistant coating.

[0030] Optionally, the addition time of the polyacrylate is step (1).

[0031] In the third aspect of the present invention, an application for preparing a stone-chip-resistant coating containing the above-mentioned coating is provided. After spraying the stone-chip-resistant coating on the bottom of the car, bake it at 130 - 165 °C for 15 - 30 min to form a stone-chip-resistant coating layer.

[0032] Optionally, the thickness of the stone-chip-resistant coating layer is 0.8 - 1.2 mm.

[0033] The beneficial effects of the present invention include but are not limited to:

[0034] 1. The green high-foaming and high-stone-chip-resistant coating according to the present invention has green, non-toxic and environmentally friendly properties. The aconitate ester plasticizer used in the stone-chip-resistant coating is a bio-based plasticizer, which is safer than phthalate plasticizers and will not cause any toxic side effects to the human body.

[0035] 2. For the green highly foamed and highly stone-chip resistant coating according to the present invention, compared with the epoxy soybean oil plasticizer which is also non-toxic to the human body, aconitate can be effectively compatible with PVC. The good compatibility promotes better foaming of the foaming agent, and the comprehensive weight reduction of the coating layer can reach 5-6 kg.

[0036] 3. For the green highly foamed and highly stone-chip resistant coating according to the present invention, the aconitate plasticizer used has a suitable molecular weight range (342-510 g / mol). When the number of carbon atoms in the ester group chain ≤ 8, good plasticizing effect can be achieved, so the PVC stone-chip resistant coating has excellent cold resistance performance; when the number of carbon atoms in the ester group chain ≥ 4, the ester group carbon chain of aconitate has a certain length, and aconitate is more difficult to extract from the system. Compared with cold-resistant plasticizers such as DOA and DOS, it has better migration resistance, and the stone-chip resistant coating has better adhesion performance.

[0037] 4. For the green highly foamed and highly stone-chip resistant coating according to the present invention, the stone-chip resistant coating plasticized by the aconitate plasticizer of the present invention has better water resistance and stone-chip resistance performance. The reason is that there is one more exposed hydroxyl group in the molecular structure of citrate ester, and this hydroxyl group is easy to absorb water, which affects the water resistance and stone-chip resistance performance of artificial leather.

[0038] 5. For the green highly foamed and highly stone-chip resistant coating according to the present invention, polyacrylate can also be used in combination with aconitate to jointly achieve a plasticizing effect. Polyacrylate also contains an ester group and has good compatibility with PVC. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] The drawings described herein are used to provide a further understanding of the present invention and constitute a part of the present invention. The schematic embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation to the present invention. In the drawings:

[0040] Figure 1 It is a comparison chart of the mechanical property test results of Example 1 and Comparative Example 5 of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0041] The present invention will be described in detail below with reference to the embodiments. However, the present invention is not limited to these embodiments. Unless otherwise specified, the raw materials used in the embodiments and comparative examples of the present invention are obtained through commercial channels.

[0042] In the embodiments of the present invention, the PVC paste resin is purchased from Xinjiang Tianye (Group) Co., Ltd., with the grades: TPM-31 (degree of polymerization 1200) and TPL-31 (degree of polymerization: 1100 and 1000); the calcium carbonate is purchased from Jiujiang Bailu New Materials Co., Ltd., with the grade: precipitated calcium carbonate (PCC); the epoxy resin is purchased from Laizhou Baichen Insulating Materials Co., Ltd., with the grade E51; the calcium oxide is purchased from Zibo Renrong Calcium Industry Co., Ltd., with the grade: ultra-fine calcium oxide (CaO-UF); the mercaptomethyltin is purchased from Foshan Tianshengda Metal Materials Co., Ltd., with the grade: MT-181; the polyurethane foaming agent is purchased from Zibo Aohong Chemical Technology Co., Ltd., with the grade HFC-245fa; the LBCB-1 thixotropic lubricant is purchased from Hubei Xinrunde Chemical Co., Ltd., with the grade: LBCB-1A; the n-butyl acrylate is purchased from Shanghai Merck Chemical Technology Co., Ltd., with the grade: PBA-200; the isooctyl acrylate is purchased from Shanghai Jixiang Biotechnology Co., Ltd.

[0043] In addition, the molecular weights of the aconitic acid esters involved in the examples and comparative examples are shown in Table 1 below.

[0044] Table 1

[0045] Number Type of aconitate Molecular weight of aconitate Example 1 Tributyl aconitate 342 g / mol Example 2 Trihexyl aconitate 426 g / mol Example 3 Trioctyl aconitate 510 g / mol Comparative Example 9 Trimethyl aconitate 216 g / mol Comparative Example 10 Tripropyl aconitate 300 g / mol Comparative Example 11 Tridecyl aconitate 595 g / mol

[0046] Example 1

[0047] This example provides a green high-foaming high-stone-chip-resistant coating and its preparation method. The stone-chip-resistant coating, by weight, comprises the following components: 100 parts of PVC paste resin, 40 parts of filler, 65 parts of aconitic acid ester, 7 parts of adhesion promoter, 3 parts of moisture absorbent, 5 parts of stabilizer, 5 parts of foaming agent, and 2 parts of thixotropic agent. Among them, the degree of polymerization of the PVC paste resin is 1100, the filler is calcium carbonate, the aconitic acid ester is tributyl aconitate, the adhesion promoter is epoxy resin, the moisture absorbent is calcium oxide, the stabilizer is mercaptomethyltin, the foaming agent is polyurethane foaming agent, and the thixotropic agent is LBCB-1 thixotropic lubricant.

[0048] The preparation steps of the stone-chip-resistant coating include:

[0049] (1) Heat and stir the PVC paste resin. When the temperature reaches 80 °C, add 40 parts of calcium carbonate, 65 parts of tributyl aconitate, and 7 parts of epoxy resin, and stir and mix evenly.

[0050] (2) Add 3 parts of calcium oxide, 5 parts of mercaptomethyltin, and 2 parts of LBCB-1 thixotropic lubricant, continue to stir until mixed evenly, and discharge and cool down to room temperature.

[0051] (3) Mix the product obtained in step (2) with 5 parts of polyurethane foaming agent, and stir at room temperature for 3 h to obtain the stone-chip-resistant coating.

[0052] Example 2

[0053] The present embodiment provides a green high foaming high stone-smash resistance coating and a preparation method thereof, wherein the stone-smash resistance coating comprises the following components by weight: 100 parts of PVC paste resin, 40 parts of filler, 65 parts of aconitate, 7 parts of adhesion promoter, 3 parts of moisture absorber, 5 parts of stabilizer, 5 parts of foaming agent, and 2 parts of thixotropic agent. The polymerization degree of the PVC paste resin is 1000, the filler is calcium carbonate, the aconitate is tri-n-hexyl aconitate, the adhesion promoter is epoxy resin, the moisture absorber is calcium oxide, the stabilizer is methyl tin mercaptan, the foaming agent is polyurethane foaming agent, and the thixotropic agent is LBCB-1 thixotropic lubricant.

[0054] The preparation steps of the anti-stone impact coating include:

[0055] (1) Heat and stir the PVC paste resin. When the temperature reaches 80° C., add 40 parts of calcium carbonate, 65 parts of tri-n-hexyl aconitate, and 7 parts of epoxy resin and stir to mix well.

[0056] (2) Add 3 parts of calcium oxide, 5 parts of methyltin mercaptide and 2 parts of LBCB-1 thixotropic lubricant, continue stirring until mixed, and cool the material to room temperature;

[0057] (3) The product obtained in step (2) is mixed with 5 parts of polyurethane foaming agent and stirred at room temperature for 3 hours to obtain the anti-stone chip coating.

[0058] Example 3

[0059] The present embodiment provides a green high foaming high stone chip resistance coating and a preparation method thereof, wherein the stone chip resistance coating comprises the following components by weight: 100 parts of PVC paste resin, 40 parts of filler, 65 parts of aconitate, 7 parts of adhesion promoter, 3 parts of moisture absorber, 5 parts of stabilizer, 5 parts of foaming agent, and 2 parts of thixotropic agent. The polymerization degree of the PVC paste resin is 1200, the filler is calcium carbonate, the aconitate is tri-n-octyl aconitate, the adhesion promoter is epoxy resin, the moisture absorber is calcium oxide, the stabilizer is methyl tin mercaptan, the foaming agent is polyurethane foaming agent, and the thixotropic agent is LBCB-1 thixotropic lubricant.

[0060] The preparation steps of the anti-stone impact coating include:

[0061] (1) Heat and stir the PVC paste resin. When the temperature reaches 80° C., add 40 parts of calcium carbonate, 65 parts of tri-n-octyl aconitate, and 7 parts of epoxy resin and stir to mix well.

[0062] (2) Add 3 parts of calcium oxide, 5 parts of methyltin mercaptide and 2 parts of LBCB-1 thixotropic lubricant, continue stirring until mixed, and cool the material to room temperature;

[0063] (3) Mix the product obtained in step (2) with 5 parts of polyurethane foaming agent and stir at room temperature for 3 h to obtain the anti-chip coating.

[0064] Example 4

[0065] This example provides a green high-foaming and high anti-chip coating and its preparation method. The anti-chip coating, by weight, comprises the following components: 100 parts of PVC paste resin, 40 parts of filler, 65 parts of aconitic acid ester, 7 parts of adhesion promoter, 3 parts of moisture absorbent, 5 parts of stabilizer, 5 parts of foaming agent, 2 parts of thixotropic agent, and 5 parts of polyacrylate. Among them, the degree of polymerization of the PVC paste resin is 1100, the filler is calcium carbonate, the aconitic acid ester is tributyl aconitate, the adhesion promoter is epoxy resin, the moisture absorbent is calcium oxide, the stabilizer is mercaptomethyltin, the foaming agent is polyurethane foaming agent, the thixotropic agent is LBCB-1 thixotropic lubricant, and the polyacrylate is isooctyl acrylate.

[0066] The preparation steps of the anti-chip coating include:

[0067] (1) Heat and stir the PVC paste resin. When the temperature reaches 80 °C, add 40 parts of calcium carbonate, 65 parts of tributyl aconitate, 5 parts of isooctyl acrylate, and 7 parts of epoxy resin, and stir to mix evenly.

[0068] (2) Add 3 parts of calcium oxide, 5 parts of mercaptomethyltin, and 2 parts of LBCB-1 thixotropic lubricant, continue to stir until mixed evenly, and discharge and cool down to room temperature.

[0069] (3) Mix the product obtained in step (2) with 5 parts of polyurethane foaming agent and stir at room temperature for 3 h to obtain the anti-chip coating.

[0070] Example 5

[0071] This example provides a green high-foaming and high anti-chip coating and its preparation method. The anti-chip coating, by weight, comprises the following components: 100 parts of PVC paste resin, 40 parts of filler, 65 parts of aconitic acid ester, 7 parts of adhesion promoter, 3 parts of moisture absorbent, 5 parts of stabilizer, 5 parts of foaming agent, 2 parts of thixotropic agent, and 5 parts of polyacrylate. Among them, the degree of polymerization of the PVC paste resin is 1100, the filler is calcium carbonate, the aconitic acid ester is tributyl aconitate, the adhesion promoter is epoxy resin, the moisture absorbent is calcium oxide, the stabilizer is mercaptomethyltin, the foaming agent is polyurethane foaming agent, the thixotropic agent is LBCB-1 thixotropic lubricant, and the polyacrylate is n-butyl acrylate.

[0072] The preparation steps of the anti-chip coating include:

[0073] (1) Heat and stir the PVC paste resin. When the temperature reaches 80 °C, add 40 parts of calcium carbonate, 65 parts of tributyl aconitate, 5 parts of n-butyl polyacrylate, and 7 parts of epoxy resin, and stir until evenly mixed;

[0074] (2) Add 3 parts of calcium oxide, 5 parts of mercapto methyl tin, and 2 parts of LBCB-1 thixotropic lubricant, continue to stir until evenly mixed, and discharge and cool down to room temperature;

[0075] (3) Mix the product obtained in step (2) with 5 parts of polyurethane foaming agent and stir at room temperature for 3 h to obtain the stone chip resistant coating.

[0076] Example 6

[0077] The specific implementation method of this example is basically the same as that of Example 1, except that the added amount of aconitate is 60 parts.

[0078] Example 7

[0079] The specific implementation method of this example is basically the same as that of Example 1, except that the added amount of aconitate is 120 parts.

[0080] Comparative Example 1

[0081] The specific implementation method of this comparative example is basically the same as that of Example 1, except that the added amount of aconitate is 40 parts.

[0082] Comparative Example 2

[0083] The specific implementation method of this comparative example is basically the same as that of Example 1, except that the added amount of aconitate is 150 parts.

[0084] Comparative Example 3

[0085] The specific implementation method of this comparative example is basically the same as that of Example 1, except that the aconitate is replaced with an equal amount of dibutyl phthalate as a plasticizer.

[0086] Comparative Example 4

[0087] The specific implementation method of this comparative example is basically the same as that of Example 1, except that the aconitate is replaced with an equal amount of DOA as a plasticizer.

[0088] Comparative Example 5

[0089] The specific implementation method of this comparative example is basically the same as that of Example 1, except that the aconitate is replaced with an equal amount of epoxidized soybean oil (purchased from: Shenzhen Jinze Wanchang Petrochemical Co., Ltd., grade: ESO6) as a plasticizer.

[0090] Comparative Example 6

[0091] This comparative example is basically the same as the specific implementation manner of Example 1, except that aconitic acid ester is replaced with an equal amount of tributyl citrate as a plasticizer.

[0092] Comparative Example 7

[0093] This comparative example is basically the same as the specific implementation manner of Example 1, except that PVC paste resin is replaced with a general-purpose resin with a polymerization degree of 1100 (purchased from Xinjiang Tianye (Group) Co., Ltd., grade: SG-5).

[0094] Comparative Example 8

[0095] This comparative example is basically the same as the specific implementation manner of Example 1, except that the polymerization degree of PVC paste resin is 1700 (purchased from Xinjiang Tianye (Group) Co., Ltd., grade: TPH-31).

[0096] Comparative Example 9

[0097] This comparative example is basically the same as the specific implementation manner of Example 1, except that the aconitic acid ester is trimethyl aconitate.

[0098] Comparative Example 10

[0099] This comparative example is basically the same as the specific implementation manner of Example 1, except that the aconitic acid ester is tributyl aconitate.

[0100] Comparative Example 11

[0101] This comparative example is basically the same as the specific implementation manner of Example 1, except that the aconitic acid ester is tridecyl aconitate.

[0102] Performance Test

[0103] Perform performance tests on the stone impact resistant coatings prepared in the examples and comparative examples, including dry time at 120 °C, tensile strength, elongation at break, adhesion grade, and stone impact resistance test, etc.

[0104] 1. Dry time at 120 °C

[0105] Spray the stone impact resistant coatings prepared in Examples 1 to 7 and Comparative Examples 1 to 8 on the surface of an electrophoretic paint steel plate substrate with a thickness of 1 mm, and then place the obtained specimens in an oven and bake at 140 °C to detect the dry time; if the dry time > 40 min, it is unqualified.

[0106] 2. Tensile strength, elongation at break

[0107] Refer to GB / T 528-2009 to prepare a spline of the stone chip resistant coating for tensile strength and elongation at break tests. Set the moving speed of the tensile machine clamp at 200±2 mm / min and the specimen gauge length at 25 mm.

[0108] 3. Adhesion test

[0109] Place the test panel on a horizontal tabletop. Use a wallpaper knife and a ruler to draw two parallel lines 5 mm apart on its surface. The wallpaper knife should cut through to the substrate without damaging it. Use the wallpaper knife to cut open the adhesive surface between the parallel lines, gently pry it up to separate the stone chip resistant primer from the substrate. Hold the lifted part by hand with the force direction perpendicular to the bottom plate until the lifted part breaks. Judge the adhesion grade according to the grade judgment standard. Adhesion grade judgment standard: Grade 1 means no adhesion, the coating has no adhesion to the substrate and is completely separated from the substrate. Grade 2 means certain adhesion, and part (<90%) of the adherent remains on the substrate. Grade 3 means sufficient adhesion, more than 90% of the coating remains on the substrate, and only a little detaches. Grade 4 means good adhesion, 100% of the material remains on the substrate and tears by itself.

[0110] 4. Stone chip resistance

[0111] Spray the stone chip resistant coatings prepared in the examples and comparative examples on the surface of the electrophoretic paint steel substrate in the standard of 190*100*3 mm, and bake at 140 °C for 30 min. Use a stone chip resistance tester to spray 1 kg of stones onto the test panel within 20 s under a pressure of 5 bar. Refer to the test method specified in GB / T 1771-2007 for neutral salt spray test, and the treatment time is 240 h. After the test, record the number of rust spots. The fewer the number of spots, the better the stone chip resistance performance.

[0112] 5. Volatility test

[0113] Test the volatility of the plasticizers (such as aconitic acid esters, phthalate plasticizers, epoxidized soybean oil, DOA, tributyl citrate) involved in the examples and comparative examples in PVC to reflect the volatility levels of different types of plasticizers. Refer to HG / T 4458-2012 "Determination of Plasticizer Loss in Plastics - Activated Carbon Method" for the test. The test temperature is 70 °C and the test time is 24 h.

[0114] 6. Glass transition temperature (T g ) test

[0115] Test the glass transition temperature (T g ) of the sample through a dynamic mechanical analyzer. Test conditions: Use nitrogen as the carrier gas, the test temperature range is -40 to -80 °C, the heating rate is 3 °C / min, and the frequency is 1 Hz. The glass transition temperature can characterize the plasticizing efficiency of the plasticizer. The lower the glass transition temperature of the stone chip resistant coating after plasticization, the higher the plasticizing efficiency.

[0116] 7. Low-temperature brittleness temperature

[0117] Test according to GB / T 15256-2014.

[0118] 8. Foaming rate

[0119] Measure the volume V1 of the coating without foaming agent added, and the volume V2 of the coating after foaming with the foaming agent added; foaming rate = (V2 - V1) / V1.

[0120] 9. Specific gravity

[0121] Test by the specific gravity cup method according to GB / T 13354-1992.

[0122] 10. Water resistance

[0123] Test the water resistance of the samples of the examples and comparative examples according to GB / T 9274.1988, measure the foaming time of the test samples and record. The later the foaming, the better the water resistance.

[0124] The test results of the above indicators are shown in Table 2 and Table 3 below.

[0125] 11. Toxicological test

[0126] 1) Refer to GB 15193.5-2014 "National Food Safety Standard Mammalian Erythrocyte Micronucleus Test" to test the genotoxicity of the plasticizer. Positive indicates genotoxicity, and negative indicates no genotoxicity. The test results show that when the plasticizer is aconitate, epoxidized soybean oil or tributyl citrate, the test results are all negative; when the plasticizer is dibutyl phthalate (DBP), dioctyl phthalate or DOA, the test results are all positive.

[0127] 2) Refer to GB / T 21853-2008 "Test for Partition Coefficient (n-Octanol-Water) of Chemicals by Shake Flask Method" to test the bioaccumulation of the material. According to the standard of "Biological Accumulation Test of Benthic Oligochaete in Chemical Sediments", when logPow>3, the material is considered to have certain bioaccumulation; when log Pow<3, the material has no bioaccumulation. It is detected that when the plasticizer is tributyl aconitate, the log Pow of the sample is 2.95; when the plasticizer is trihexyl aconitate, the log Pow of the sample is 2.96; when the plasticizer is trioctyl aconitate, the log Pow of the sample is 2.97; when the plasticizer is dibutyl phthalate, the log Pow of the sample is 4.47; when the plasticizer is DOA, the log Pow of the sample is 3.86; when the plasticizer is epoxidized soybean oil, the log Pow of the sample is 2.98; when the plasticizer is tributyl citrate, the log Pow of the sample is 2.97.

[0128] Table 2

[0129]

[0130]

[0131] Table 3

[0132]

[0133] The data in Table 2 and Table 3 show that the experimental results of Examples 1 to 3 of the present invention verify that when aconitic acid esters with 4 to 8 carbon atoms in the ester group are used for PVC plasticization, they have good plasticization effects, and plasticized products with appropriate tensile strength and elongation at break can be obtained. When combined with other components, it is more conducive to obtaining anti-chip coatings with better anti-chip performance, adhesion, etc. At the same time, when the carbon number of the ester group is in this range, the aconitic acid ester can stably exist in the PVC material and is not easily migrated and volatilized. The dry-to-touch time of the anti-chip coatings in Examples 1 to 7 at 120 °C all meet the relevant requirements and can be completely dry within 120 °C and 40 minutes. The obtained anti-chip coatings have better comprehensive performance, excellent adhesion performance, anti-chip performance, cold resistance, water resistance and high foaming rate. Moreover, the adhesion and anti-chip performance of the anti-chip coatings plasticized by aconitic acid esters are higher, indicating that with the participation of aconitic acid esters, each component can achieve better reinforcement and performance improvement effects. Examples 4 and 5 have higher strength and toughness compared with Example 1, indicating that the addition of polyacrylate has an obvious strengthening and toughening effect.

[0134] Comparing the experimental results of Comparative Example 1 with Comparative Examples 4 and 5, it is found that when the plasticizer is changed to DOA, the cold resistance of the PVC anti-chip coating is better, but the DOA-based plasticizer has general migration resistance, resulting in the plasticizer being unable to stably exist in the PVC coating and the adhesion of the anti-chip coating being reduced. When the plasticizer is changed to epoxidized soybean oil, the compatibility between epoxidized soybean oil and PVC is poor, so the plasticization and foaming effects are average. Comparing the experimental results of Examples 1, 6, and 7 with Comparative Examples 1 and 2, it is found that the addition amount of aconitic acid ester needs to meet a certain range. When the addition amount is too low, the PVC anti-chip coating will have problems of poor plasticization effect and insufficient cold resistance; when the addition amount is too high, although the plasticization effect is better and the cold resistance is better, the adhesion of the anti-chip coating becomes worse.

[0135] Comparing the experimental results of Example 1 and Comparative Example 6, it is found that the water resistance and stone impact resistance of the stone impact resistant coating plasticized with tributyl citrate are poor. The reason is that the difference in structure between aconitate and citrate is that there is an extra exposed hydroxyl group in the molecular structure of citrate, which reduces the water resistance and stone impact resistance of the stone impact resistant coating. Comparing the experimental data of Example 1 and Comparative Example 7, it is found that when the paste resin is replaced with a general-purpose resin with the same degree of polymerization, the foaming rate of the obtained stone impact resistant coating decreases. The reason is that the general-purpose resin has poor ability to absorb plasticizer, the fluidity of the system decreases, and then the uniform distribution of the foaming agent in the system and the foaming rate of the foaming agent are affected.

[0136] Comparing the experimental results of Example 1 and Comparative Example 8, it is found that when the PVC paste resin with a degree of polymerization of 1100 is replaced with the PVC paste resin with a degree of polymerization of 1900, the fluidity of the PVC system is low at a higher degree of polymerization, and a single mechanical stirring cannot evenly disperse the plasticizer in the system, resulting in the deterioration of the mechanical properties of the stone impact resistant coating.

[0137] Comparing the experimental results of Example 1 and Comparative Examples 9-11, it is found that when aconitate with a suitable molecular weight is blended with PVC paste resin, it not only has high plasticization efficiency, enabling the stone chip resistant coating to have better cold resistance, but also can promote the efficient foaming of the foaming agent. The obtained foamed coating not only has uniform foam size and regular shape, but also the foaming agent has a high foaming rate. The higher the plasticization efficiency, the better the compatibility between the PVC resin and aconitate. High compatibility can endow the foaming agent with a higher foaming rate, and the specific gravity of the coating layer can be significantly reduced. As the number of carbon atoms in the ester group and the molecular weight of the aconitate plasticizer increase, the glass transition temperature of the stone chip resistant coating product shows an upward trend, indicating that the plasticization effect of aconitate deteriorates as the molecular weight increases. The reason is that as the length of the ester chain of aconitate increases, the compatibility between the plasticizer and PVC deteriorates. According to the experimental results, when the plasticization effect is better, the foaming rate of the foaming agent is higher, and at the same time, the specific gravity of the stone chip resistant coating layer is lower, proving that within a certain range, the lower the molecular weight of aconitate, the better its compatibility with PVC, and therefore the higher the foaming rate of the foaming agent. However, when aconitate is replaced with trimethyl aconitate with a low number of carbon atoms in the ester group and a corresponding low molecular weight, it is more likely to be extracted, affecting the plasticization and foaming effects; when the plasticizer is replaced with tridecyl aconitate with a higher number of carbon atoms in the ester group and a high molecular weight, the too long ester chain leads to poor compatibility between aconitate and PVC, and at the same time, the foaming rate of the foaming agent also decreases. Therefore, when the number of carbon atoms in the ester group of the aconitate plasticizer is in the range of 4-8 and the molecular weight of aconitate is in the range of 340-510 g / mol, the compatibility between aconitate and PVC is the best. At this time, the foaming agent has a good foaming rate, the specific gravity of the stone chip resistant coating layer is also lower, and the plasticizer is less likely to migrate out. At the same time, it is found that the number of carbon atoms in the ester group and the molecular weight of aconitate will also affect the cold resistance of the stone chip resistant coating. When the number of carbon atoms in the aconitate group ≤ 8 and the molecular weight of aconitate is less than 510 g / mol, the triester group structure of aconitate can be effectively compatible with PVC, improving the mobility of the PVC molecular chain, with an obvious plasticization effect, and thus making the material exhibit good cold resistance, and the stone chip resistant PVC coating has a lower low-temperature brittleness temperature. When the number of carbon atoms in the ester group ≥ 4, the molecular weight of aconitate is relatively higher, and the migration resistance of the plasticizer is higher. When the number of carbon atoms in the ester group of aconitate < 4, the molecular weight of aconitate is relatively lower, less than 342 g / mol, and aconitate is more likely to be extracted, resulting in a reduction in the plasticization effect and affecting the adhesion of the stone chip resistant coating; when the aconitate group > 8, the molecular weight of aconitate is higher. At this time, although aconitate is difficult to be extracted from PVC, due to the increase in the length of the polar ester group molecular chain, the polarity of aconitate will also increase accordingly, resulting in poor compatibility with PVC, and the plasticization effect of aconitate on PVC deteriorates, which will affect the cold resistance of the stone chip resistant coating. The stone chip resistant coatings prepared from tributyl aconitate, trihexyl aconitate, and trioctyl aconitate in Examples 1-3 have a lower brittleness temperature and better cold resistance, enabling new energy vehicles to have a longer endurance in cold weather.

[0138] The toxicological test results show that when aconitate is added to the stone impact resistant coating, it can not only exert a significant plasticizing effect, but also has the characteristics of being green and harmless and not affecting physical health compared with petroleum-based phthalate plasticizers. The stone impact resistant coating obtained after adding PVC plasticizer has higher safety and will not produce any toxic side effects even after long-term use. When the plasticizer is aconitate, the log Pow of the sample is less than 3, and it will not affect human health after use. Therefore, the stone impact resistant coating prepared by the present invention meets the requirements of the tram exterior material and can meet the production requirements of the stone impact resistant coating for new energy trams.

[0139] As mentioned above, only the embodiments of the present invention are given. The protection scope of the present invention is not limited by these specific embodiments, but is determined by the claims of the present invention. For those skilled in the art, the present invention can have various changes and modifications. Any modification, equivalent replacement, improvement, etc. made within the technical idea and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A green high foaming and high stone impact resistance coating, characterized in that: The anti-stone chip coating comprises the following components by weight: 100 parts of PVC resin, 35-50 parts of filler, 60-120 parts of aconitate, 5-10 parts of adhesion promoter, 1-5 parts of moisture absorbent, 1-8 parts of stabilizer, 3-8 parts of foaming agent, 0.1-5 parts of thixotropic agent and 0-10 parts of polyacrylate.

2. The green high foaming and high stone impact resistance coating according to claim 1, characterized in that: The PVC resin is a PVC paste resin with a polymerization degree of 1000-1200.

3. The green high foaming and high stone impact resistance coating according to claim 1, characterized in that: The aconitate ester is selected from one or more of tri-n-butyl aconitate, tri-n-pentyl aconitate, tri-n-hexyl aconitate, tri-n-heptyl aconitate, tri-n-octyl aconitate, and tri(2-ethylhexyl) aconitate.

4. The green high foaming and high stone impact resistance coating according to claim 1, characterized in that: The filler is one or more of calcium carbonate, nano calcium carbonate, graphene, kaolin and diatomaceous earth.

5. The green high foaming and high stone impact resistance coating according to claim 1, characterized in that: The adhesion promoter is one or more of epoxy resin, polyamide resin and polyurethane resin.

6. The green high foaming and high stone impact resistance coating according to claim 1, characterized in that: The desiccant is calcium oxide.

7. The green high foaming and high stone impact resistance coating according to claim 1, characterized in that: The stabilizer is one or more of methyl tin mercaptan, zinc oxide, zinc stearate, aluminum stearate, potassium stearate, and calcium zinc stabilizer; The foaming agent is a polyurethane foaming agent; The thixotropic agent is one or more of LBCB-1 thixotropic lubricant, silicon dioxide, and organic bentonite.

8. The green high foaming and high stone impact resistance coating according to claim 1, characterized in that: The polyacrylate is selected from one or more of poly(n-butyl acrylate), poly(n-pentyl acrylate), poly(n-hexyl acrylate), poly(n-heptyl acrylate), poly(n-octyl acrylate) or poly(isooctyl acrylate).

9. A method for preparing a green high-foaming and high-stone-smashing resistance coating as claimed in any one of claims 1 to 8, characterized in that: The preparation steps of the anti-stone impact coating include: (1) heating and stirring the PVC resin, and when the temperature reaches 75-90° C., adding filler, aconitate, and adhesion promoter according to the formula ratio, and stirring to mix; (2) Add hygroscopic agent, stabilizer and thixotropic agent according to the formula ratio, continue stirring until the mixture is uniform, and cool the discharged material to room temperature; (3) The product obtained in step (2) is mixed with a foaming agent according to a formula ratio, and stirred at room temperature for 1 to 5 hours to obtain the anti-stone chip coating.

10. An application of the green high foaming and high stone impact resistance coating as claimed in any one of claims 1 to 8, characterized in that: After spraying the anti-stone chipping paint on the bottom of the car, baking at 130-165° C. for 15-30 minutes to form an anti-stone chipping paint coating; The thickness of the anti-stone impact paint coating is 0.8 to 1.2 mm.

Images