Waterproof heat-conducting hot-melt sealant for vehicle and preparation method of waterproof heat-conducting hot-melt sealant

Abstract

The invention discloses a waterproof heat-conducting hot-melt sealant for vehicles and a preparation method thereof. The waterproof heat-conducting hot-melt sealant comprises the following raw materials in parts by weight: 15-45 parts of polyolefin with a melt index of 2-5g / 10min; 15 to 30 parts of polyolefin with a melt index of 6 to 15 g / 10 min; 2 to 10 parts of polyolefin with a melt index of 150 to 400 g / 10 min; 0-10 parts of epoxy resin; 2-7 parts of modified boron nitride; 2 to 10 parts of fiber; 3 to 10 parts of an ethylene-butyl acrylate copolymer; 0 to 10 parts of an ethylene-methyl acrylate copolymer; 10 to 20 parts of petroleum resin; 0.5 to 1.5 parts of a cross-linking agent; 1-2 parts of an antioxidant; 2-6 parts of talcum powder; the waterproof heat-conducting hot-melt sealant for the vehicle can be subjected to injection molding, is suitable for various complex structures, is long in opening time, stable in physical property at the temperature lower than 140 DEG C, is suitable for a high-temperature application environment, and has heat conductivity, excellent adhesive strength and excellent fatigue resistance.

Description

Technical Field

[0001] The invention belongs to the technical field of hot-melt sealants, and in particular relates to a waterproof and heat-conductive hot-melt sealant for vehicles and a preparation method thereof. Background Art

[0002] At present, people's requirements for automobile comfort are constantly increasing, and vibration reduction and noise reduction have always been a hot topic of research. If you want to achieve a good noise reduction effect, you must have a high requirement for the overall air tightness of the car. However, with the rise of new energy vehicles, cars that only meet air tightness but have defects in water tightness will have certain risks.

[0003] The air tightness test of a car is to fill a certain volume of gas into the car body, and then detect the change of internal air pressure after maintaining the pressure for a period of time. The pressure difference is required to be small. Even if the output pressure is stable, as long as there is a pressure difference, even if the pressure is stable, it means that there is a fixed defect in the sealing position. In such defective positions, the gas is colorless and odorless and is not easy to detect, but the liquid will magnify the defect, resulting in seepage, leakage, etc.

[0004] New energy vehicles are corroded by rain, road water and other factors, and the batteries will be affected by water, resulting in a decrease in battery performance, or dangerous situations such as heating, short circuit and even explosion. When traditional vehicles encounter road water, the lower body cavity is also easily invaded by water, increasing the probability of the power system stalling. Therefore, meeting the water tightness requirements has become one of the important indicators of vehicle safety.

[0005] However, there is no development of automotive waterproof heat-conducting hot-melt sealant in the prior art. Chinese patent CN101781534A discloses automotive butyl hot-melt sealant and its manufacturing method, which includes the following components and corresponding weight parts: butyl rubber 5-30 parts, carbon 5 resin 10-20 parts, polyisobutylene 10-40 parts, filler 30-50 parts. The automotive waterproof heat-conducting hot-melt sealant disclosed in the patent is used to paste waterproof membranes, and its application range is relatively limited, and this butyl hot-melt sealant cannot be injection molded. Summary of the invention

[0006] In order to solve the above technical problems, the present invention provides a vehicle-use waterproof and thermally conductive hot-melt sealant and a preparation method thereof. The vehicle-use waterproof and thermally conductive hot-melt sealant can be injection molded, is suitable for a variety of complex structures, has a long open time, has stable physical properties below 140°C, is suitable for high-temperature application environments, and has thermal conductivity, excellent adhesion, and excellent anti-fatigue performance.

[0007] The technical solution adopted by the present invention is as follows:

[0008] A waterproof and heat-conductive hot-melt sealant for vehicles, comprising the following raw materials in parts by weight:

[0009] 15 to 45 parts of polyolefin having a melt index of 2 to 5 g / 10 min;

[0010] 15 to 30 parts of polyolefin having a melt index of 6 to 15 g / 10 min;

[0011] 2 to 10 parts of polyolefin having a melt index of 150 to 400 g / 10 min;

[0012] Epoxy equivalent weight 150-1450 g / equivalent epoxy resin 0-10 parts;

[0013] 2-7 parts of modified boron nitride;

[0014] Fiber 2-10 parts;

[0015] 3-10 parts of ethylene-butyl acrylate copolymer;

[0016] Ethylene-methyl acrylate copolymer 0-10 parts;

[0017] 10-20 parts of petroleum resin with a softening point of 100-110°C;

[0018] 0.5-1.5 parts of cross-linking agent;

[0019] 1-2 parts of antioxidant;

[0020] 2 to 6 parts of talcum powder.

[0021] The polyolefin is any one or more of polyvinyl chloride resin, linear low-density polyethylene resin and POE resin.

[0022] The viscosity of epoxy resin with epoxy equivalent weight of 150-1450g / equivalent at 25℃ is 15000-3000CPS. If the equivalent weight is outside the range, the peel strength of the material will be affected, and if the viscosity is outside this range, it will affect the molding of injection molded parts.

[0023] The fiber has an aspect ratio of 10-12mm and a diameter of 10-13um. The fiber is mainly chemical fiber, including cotton nylon, spandex, acrylic fiber, aramid fiber, and polypropylene fiber. The aspect ratio is 10-12mm and the diameter is 10-13um. If it is too long, it will be difficult to process and disperse, affecting fluidity; if it is too short, the material will not be tough enough and will be prone to cracking.

[0024] The preparation method of the modified boron nitride is as follows: the boron nitride and the surface treatment agent are placed in a torque rheometer at a temperature range of 90±5°C and a rotation speed of 35±5rpm, and mixed and stirred for 42 minutes. This method reduces the thermal resistance of the boron nitride interface, grafts the modifier on the surface, enhances the interface coupling, reduces defects, and improves the adhesion between the filler and the substrate.

[0025] The surface treatment agent is any one or more of a silane coupling agent, a long-chain organic acyl chloride, oxyphosphoryl chloride, a metal organic alkoxide and an epoxy compound.

[0026] The weight ratio of the boron nitride to the surface treatment agent is 100:1-5.

[0027] The crosslinking agent is any one or more of dibenzoyl peroxide, diisopropylbenzene peroxide, di-tert-butyl peroxyisopropylbenzene, α-hydroxyalkyl phenone, acylphosphine oxide, benzophenone and its derivatives, and acrylate.

[0028] The antioxidant is any one or more of hindered phenol antioxidants, sulfur aromatic amine antioxidants, thiodipropionate, and phosphite.

[0029] The automotive waterproof heat-conductive hot-melt sealant has an open time of 40-100s at 140°C, a flow distance of 0-20mm at 140°C, a flow distance of 5-30mm at 160°C, a peel strength of 30-90N / 25mm at 180°C, and a fatigue cycle number of 2×10 5 ~5×10 5 , thermal conductivity 0.25-0.5W / m·K.

[0030] The present invention also provides a method for preparing the waterproof and heat-conductive hot-melt sealant for vehicles, which comprises the following steps: mixing and kneading the raw materials in the formula, extruding and granulating, and then injection molding. When used, the hot-melt sealant can be heated to achieve flow bonding.

[0031] The kneading conditions are mixing and kneading at 135-145° C. for 20-40 minutes.

[0032] The twin-screw granulation is adopted, and the granulation temperature is 65-70℃ in the first stage, 70-90℃ in the second stage, 60-70℃ in the third stage, and 80-85℃ in the fourth stage.

[0033] The waterproof and heat-conductive hot-melt sealant for vehicles provided by the present invention uses polyolefins with melt indexes of 2-5 g / 10min, 6-15 g / 10min and 150-400 g / 10min as main resins, so as to ensure that the hot-melt sealant can be injection molded at 80-100°C; ethylene-butyl acrylate copolymer (EBA) and ethylene-methyl acrylate copolymer (EMA) are used in raw materials to provide sufficient adhesion for the hot-melt sealant in a semi-dissolved state; modified boron nitride with heat conduction effect is also used in the raw materials to provide thermal conductivity for the hot-melt sealant, so that it can be used in positions requiring heat management; the use of petroleum resin, epoxy resin and cross-linking agent in the raw materials can increase the adhesion of the hot-melt sealant.

[0034] Compared with the prior art, the present invention has the following beneficial effects:

[0035] The automotive waterproof and thermally conductive hot-melt sealant provided by the present invention can be injection molded and is suitable for a variety of complex structures; it has a long open time and stable physical properties below 140° C., so it is suitable for high-temperature application environments, such as vehicle painting workshops; the Tg temperature range is small, it is well molded below Tg, and the material can melt and flow quickly above Tg; it has certain thermal conductivity, excellent adhesion, and anti-fatigue performance. DETAILED DESCRIPTION

[0036] The melt index of polyolefin refers to the melt index at 190°C.

[0037] The present invention is described in detail below with reference to the embodiments.

[0038] Unless otherwise specified, all raw materials in the examples and comparative examples can be directly purchased from the market. The preparation method of the modified boron nitride used in each example and comparative example is as follows: 200g of boron nitride and 10g of silane coupling agent KH560 are put into a torque rheometer at a temperature of 95°C and a speed of 40prm, and the material is discharged after stirring for 25min.

[0039] Example 1

[0040] A waterproof and heat-conductive hot-melt sealant for vehicles, the raw materials and the weight proportions of the raw materials are shown in Example 1 in Table 1.

[0041] The preparation method of the automotive waterproof heat-conductive hot-melt sealant is as follows: the raw materials in the formula amount are mixed, kneaded at 140° C. for 30 minutes, extruded and granulated by a twin-screw granulator, the granulation temperature is 65° C. in the first stage, 70° C. in the second stage, 60° C. in the third stage, and 80° C. in the fourth stage, and then injection molded.

[0042] Table 1

[0043]

[0044] Example 2

[0045] A waterproof and heat-conductive hot-melt sealant for vehicles, the raw materials and the weight proportions of the raw materials are shown in Example 2 in Table 1.

[0046] The preparation method of the automotive waterproof heat-conductive hot-melt sealant is as follows: mixing the raw materials in the formula, kneading at 135° C. for 40 minutes, extruding and granulating with a twin-screw granulator, with the granulation temperature of 70° C. for the first stage, 90° C. for the second stage, 70° C. for the third stage, and 85° C. for the fourth stage, and then injection molding.

[0047] Example 3

[0048] A waterproof and heat-conductive hot-melt sealant for vehicles, the raw materials and the weight proportions of the raw materials are shown in Example 3 in Table 1.

[0049] The preparation method of the automotive waterproof heat-conductive hot-melt sealant is as follows: the raw materials in the formula amount are mixed, kneaded at 145° C. for 20 minutes, extruded and granulated by a twin-screw granulator, the granulation temperature is 65° C. in the first stage, 80° C. in the second stage, 65° C. in the third stage, and 80° C. in the fourth stage, and then injection molded.

[0050] Example 4

[0051] A waterproof and heat-conductive hot-melt sealant for vehicles, the raw materials and the weight proportions of the raw materials are shown in Example 4 in Table 1.

[0052] The preparation method of the automotive waterproof heat-conductive hot-melt sealant is as follows: the raw materials in the formula amount are mixed, kneaded at 140° C. for 30 minutes, extruded and granulated by a twin-screw granulator, the granulation temperature is 70° C. for the first stage, 90° C. for the second stage, 65° C. for the third stage, and 80° C. for the fourth stage, and then injection molded.

[0053] Comparative Examples 1 to 4

[0054] The preparation methods of the sealants in Comparative Examples 1 to 4 are the same as those in Example 1. The raw materials and weight portions of the sealants are shown in Table 2.

[0055] Table 2

[0056]

[0057]

[0058] The raw material particles of the hot melt sealant prepared in the above embodiments and comparative examples are injection molded into a specified size, and their various properties are tested. The test method is as follows:

[0059] Open time s, flow distance mm: A 10×10×10mm rubber block is fixed on a horizontal sheet metal (marked to leave the original position) and baked. After the baking, the distance from the boundary where the rubber flows to the unbaked boundary is measured, and the farthest boundary is used as the standard. The rubber flow time is also recorded.

[0060] 180° peel strength N / 25mm: GBT 2790-1995 adhesive 180° peel strength test.

[0061] Fatigue cycle number: GB / T528-1998 Determination of tensile properties of vulcanized rubber and thermoplastic rubber.

[0062] Thermal conductivity (W / m·K): YB / T 4130-2005 Thermal conductivity test of refractory materials.

[0063] Waterproof verification

[0064] The same metal sample to be sealed is hot-melt sealed with the sealants prepared in each embodiment and comparative example, and the hot-melt temperature is 200°C; then it is placed in a cavity with a water column height of 120mm, and a pressure of 1Kpa is applied to the cavity for 30 minutes; then the height of the water column is observed. If the height of the water column decreases compared with the previous one, it means that the sealing effect of the sealant is not good and water leakage occurs; if the height of the water column does not decrease compared with the previous one, it means that the sealing effect of the sealant is good and has good waterproofness. The test results are shown in Table 3.

[0065] Table 3

[0066]

[0067]

[0068] From the comparison between Example 1 and Comparative Example 1, it can be seen that by adding high melt index polyolefin, the open time of the hot melt adhesive can be prolonged, and the hot melt adhesive can flow over a longer distance to block gaps.

[0069] From the comparison between Example 1 and Comparative Example 2, it can be seen that the addition of EMA and EBA can increase the toughness of the material, further improve the adhesion between the material and the substrate, and provide a longer-lasting watertight function.

[0070] From the comparison between Example 1 and Comparative Example 3, it can be seen that adding modified boron carbide to the raw materials improves the thermal conductivity of the sealant.

[0071] From the comparison between Example 1 and Comparative Example 4, it can be seen that increasing the high temperature resistant epoxy resin and improving the macromolecular polyolefin can increase the fatigue resistance of the sealant.

[0072] It can be seen from the above that only by preparing the sealant according to the raw material composition and dosage required by the present invention can the open time at 140°C be 40-100s, the flow distance at 140°C be 0-20mm, the flow distance at 160°C be 5-30mm, the peel strength at 180°C be 30-90N / 25mm, and the fatigue cycle number be 2×10 5 ~5×10 5 , thermal conductivity 0.25-0.5W / m·K. Such sealant has good waterproof, thermal conductivity and anti-fatigue properties.

[0073] The above-mentioned detailed description of a vehicle waterproof and thermally conductive hot-melt sealant and its preparation method with reference to the embodiments is illustrative rather than restrictive. Several embodiments can be listed according to the limited scope. Therefore, changes and modifications without departing from the overall concept of the present invention should fall within the scope of protection of the present invention.

Claims

1. A waterproof and thermally conductive hot melt sealant for a vehicle, characterized in that: The invention comprises the following raw materials in parts by weight: 15 to 45 parts of polyolefin having a melt index of 2 to 5 g / 10 min; 15 to 30 parts of polyolefin having a melt index of 6 to 15 g / 10 min; 2 to 10 parts of polyolefin having a melt index of 150 to 400 g / 10 min; Epoxy equivalent weight 150-1450 g / equivalent epoxy resin 0-10 parts; 2-7 parts of modified boron nitride; Fiber 2-10 parts; 3-10 parts of ethylene-butyl acrylate copolymer; Ethylene-methyl acrylate copolymer 0-10 parts; 10-20 parts of petroleum resin with a softening point of 100-110°C; 0.5-1.5 parts of cross-linking agent; 1-2 parts of antioxidant; 2 to 6 parts of talcum powder.

2. The vehicle waterproof and thermally conductive hot melt sealant according to claim 1, characterized in that: The polyolefin is any one or more of polyvinyl chloride resin, linear low-density polyethylene resin and POE resin.

3. The vehicle waterproof and thermally conductive hot melt sealant according to claim 1, characterized in that: The preparation method of the modified boron nitride is: the boron nitride and the surface treatment agent are stirred and mixed uniformly in a torque rheometer within a temperature range of 90±5°C; the surface treatment agent is any one or more of a silane coupling agent, a long-chain organic acyl chloride, oxyphosphoryl chloride, a metal organic alkoxide and an epoxy compound.

4. The waterproof and thermally conductive hot melt sealant for vehicles according to claim 1, characterized in that: The crosslinking agent is any one or more of dibenzoyl peroxide, diisopropylbenzene peroxide, di-tert-butyl peroxyisopropylbenzene, α-hydroxyalkyl phenone, acylphosphine oxide, benzophenone and its derivatives, and acrylate.

5. The waterproof and thermally conductive hot melt sealant for vehicles according to claim 1, characterized in that: The antioxidant is any one or more of hindered phenol antioxidants, sulfur aromatic amine antioxidants, thiodipropionate, and phosphite.

6. The vehicle waterproof and thermally conductive hot melt sealant according to claim 1, characterized in that: The aspect ratio of the fiber is 10-12 mm, and the diameter is 10-13 um.

7. The vehicle waterproof and thermally conductive hot melt sealant according to claim 1, characterized in that: The automotive waterproof heat-conductive hot-melt sealant has an open time of 40-100s at 140°C, a flow distance of 0-20mm at 140°C, a flow distance of 5-30mm at 160°C, a peel strength of 30-90N / 25mm at 180°C, and a fatigue cycle number of 2×10 5 ~5×10 5 , thermal conductivity 0.25-0.5W / m·K.

8. The method for preparing the waterproof and thermally conductive hot melt sealant for vehicles according to any one of claims 1 to 7, characterized in that: The preparation method comprises the following steps: mixing and kneading the raw materials in the formula amount, extruding and granulating them, and then performing injection molding.

9. The preparation method according to claim 8, characterized in that: The kneading conditions are mixing and kneading at 135-145° C. for 20-40 minutes.

10. The preparation method according to claim 8, characterized in that: The twin-screw granulation is adopted, and the granulation temperature is 65-70℃ in the first stage, 70-90℃ in the second stage, 60-70℃ in the third stage, and 80-85℃ in the fourth stage.

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