Adhesive as well as preparation method and application thereof

Abstract

The invention relates to an adhesive as well as a preparation method and application thereof. The adhesive is prepared from the following components in parts by weight: 30 to 50 parts of polypropylene random copolymer, 10 to 25 parts of polyolefin elastomer, 15 to 41 parts of maleic anhydride graft, 5 to 10 parts of nano inorganic filler and 3 to 10 parts of tackifier. Through cooperation of the polypropylene random copolymer, the polyolefin elastomer, the maleic anhydride graft, the nano inorganic filler and the tackifier, the obtained adhesive has good (initial) peel strength, keeps good peel strength under the conditions of high temperature and soaking in a cooling liquid, has good durability, and is suitable for large-scale production. The method is very suitable for preparing the automobile cooling system composite nylon cooling pipe needing to be bonded with PA and PP.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of high polymer materials, and more particularly to an adhesive, a preparation method and application thereof. BACKGROUND

[0002] The automobile cooling system is the core system for stable operation of the automobile, which can prevent the engine from overheating and inhibit the overheating of other components such as the battery, motor and controller. Liquid cooling is the mainstream way of the automobile cooling system at present, and the circulation of the cooling liquid needs to be achieved by connecting the cooling pipeline. In addition to heat dissipation, the cooling system also needs to provide heat, and the requirements for the cooling pipeline are more stringent. The scheme of the thermoplastic cooling pipeline can meet the requirements of the cooling system.

[0003] The automobile mainstream cooling pipeline is divided into three categories: PA (nylon), TPV (thermoplastic vulcanized rubber) and EPDM (ethylene propylene diene rubber), among which the nylon pipe is most widely used in new energy vehicles. The nylon pipe usually has PA as the outer layer and PP as the inner layer, and the adhesive as the key connecting material of the outer layer PA and the inner layer PP has the advantages of low temperature resistance, impact resistance and the like, and has good adhesion to the material.

[0004] CN114316808A provides an adhesive, but it is not suitable for a multi-layer co-extrusion molding process. In the multi-layer co-extrusion molding process, the adhesive can form a strong physical and chemical action with the polyamide material and the polypropylene material in a short co-extrusion time, so as to bond the inner and outer layers. However, since the multi-layer co-extrusion process is short, rapid crystallization occurs after the PA and PP are extruded from the flow channel, at which time the adhesive has limited bonding to the interface, so it is difficult to provide an adhesive suitable for a multi-layer co-extrusion molding process and capable of providing excellent peel strength.

[0005] At the same time, the components applied to the automobile cooling system have strict requirements for their safety during the service period. After the nylon pipe is assembled in the automobile cooling system, the long-term stress state will affect its durability, and the durability of the adhesive is one of the key factors affecting the durability of the nylon pipe.

[0006] In addition, the cooling pipe is actually applied in a high-temperature and cooling liquid contact environment, and the stability of the bonding peel strength after high-temperature and cooling liquid immersion also needs to be concerned. SUMMARY

[0007] The primary object of the present application is to overcome the problems existing in the prior art and provide an adhesive.

[0008] A further object of the present application is to provide a preparation method of the adhesive.

[0009] A further object of the present application is to provide the application of the adhesive in the preparation of the automobile cooling pipe.

[0010] The above object of the present application is achieved by the following technical solution. An adhesive comprises the following components in parts by weight: 30-50 parts of random copolymerized polypropylene, 10-25 parts of polyolefin elastomer, 15-41 parts of maleic anhydride graft, 5-10 parts of nano inorganic filler, 3-10 parts of tackifier, The maleic anhydride graft is a polymer obtained by the reaction of random copolymerized polypropylene, polyolefin elastomer and maleic anhydride; The residual maleic anhydride monomer content in the maleic anhydride graft is ≤0.03wt%.

[0011] In the present application, the amount of random copolymerized polypropylene can be specifically 30, 32, 35, 38, 40, 42, 45, 48, 50 parts by weight or a range value formed by any two of the above values; the amount of polyolefin elastomer can be specifically 10, 12, 15, 18, 20, 24, 25 parts by weight or a range value formed by any two of the above values; the amount of maleic anhydride graft can be specifically 15, 18, 20, 25, 28, 30, 32, 35, 38, 40 parts by weight or a range value formed by any two of the above values; the amount of nano inorganic filler can be specifically 5, 6, 7, 8, 9, 10 parts by weight or a range value formed by any two of the above values; and the amount of tackifier can be specifically 3, 4, 5, 6, 7, 8, 9, 10 parts by weight or a range value formed by any two of the above values.

[0012] In the present application, the residual maleic anhydride monomer content in the maleic anhydride graft refers to the value obtained by dividing the mass of the residual maleic anhydride monomer in the maleic anhydride graft by the mass of the maleic anhydride graft.

[0013] The residual maleic anhydride monomer in the maleic anhydride graft can be measured by acid-base titration. The specific process can be as follows: 5g of maleic anhydride graft is dissolved in 500ml of dimethylbenzene at 120℃, then cooled to room temperature and added with acetone to precipitate the maleic anhydride graft from the solution (in this process, since the maleic anhydride monomer has solubility in acetone, the maleic anhydride monomer will not precipitate), the filtrate is obtained by filtration, which is the dimethylbenzene solution of the residual maleic anhydride monomer, the filtrate is titrated with 0.1mol / L KOH / isopropyl alcohol solution, and the residual maleic anhydride monomer content in the maleic anhydride graft is obtained after calculation. The calculation formula of the residual maleic anhydride monomer content in the maleic anhydride graft is (a / b)×100%; wherein a is the mass of the residual maleic anhydride monomer calculated after titration, and b is the mass of the maleic anhydride graft containing the residual maleic anhydride monomer.

[0014] The specific maleic anhydride grafting agent with a certain residual monomer content is added to the adhesive of the present application, and the maleic anhydride grafting agent can form a strong chemical bond with nylon during multilayer co-extrusion molding, so that the adhesive has good peel strength and good peel strength under high temperature or cooling liquid immersion. At the same time, the polypropylene in the maleic anhydride grafting agent needs to be selected as a random copolymer polypropylene to ensure that the maleic anhydride grafting agent has a certain rigidity, and a polyolefin elastomer needs to be added to avoid significant degradation of the random copolymer polypropylene during the grafting reaction, otherwise the performance of the adhesive will be poor, especially the peel strength retention and durability under cooling liquid immersion conditions.

[0015] The residual maleic anhydride monomer content in the maleic anhydride grafting agent also needs to be controlled within a certain range to avoid negative effects of the residual monomer on the peel strength of the adhesive, the peel strength retention under high temperature and cooling liquid immersion conditions, and the durability.

[0016] In order to further improve the high temperature resistance, cooling liquid immersion resistance and durability of the adhesive as a bonding layer of a cooling pipe, a random copolymer polypropylene and a polyolefin elastomer need to be added to the adhesive; and the random copolymer polypropylene cannot be replaced by a homopolymer polypropylene or a terpolymer polypropylene, otherwise the performance of the adhesive will be poor (such as peel strength retention and durability under cooling liquid immersion conditions) and the adhesive will not be suitable for a cooling pipe.

[0017] The random copolymer polypropylene, the polyolefin elastomer, the maleic anhydride grafting agent and the tackifier are combined to obtain an adhesive with improved rigidity, and therefore the present application further adds a nano inorganic filler, which not only improves the rigidity of the adhesive, but also improves the specific surface area of the adhesive bonding interface, thereby further improving the performance of the adhesive. The inorganic filler cannot be selected as a micron-sized filler, otherwise the toughness of the adhesive will be deteriorated and the adhesive bonding interface will be too rough, thereby resulting in poor peel strength retention of the adhesive under high temperature and poor durability.

[0018] That is, the present application combines the random copolymer polypropylene, the polyolefin elastomer, the maleic anhydride grafting agent, the nano inorganic filler and the tackifier to obtain an adhesive with good (initial) peel strength, good peel strength retention under high temperature and cooling liquid immersion conditions, and good durability, which is very suitable for preparing a composite nylon cooling pipe of an automobile cooling system which needs to bond PA and PP.

[0019] In the present application, the mass percentage content of the random copolymer polypropylene in the adhesive is at least 20%; and the sum of the mass of the random copolymer polypropylene, the polyolefin elastomer and the maleic anhydride grafting agent in the adhesive accounts for more than 70wt% of the adhesive.

[0020] Preferably, the random copolymer polypropylene in the adhesive and the random copolymer polypropylene in the maleic anhydride grafting product independently have a melt flow rate of 0.2-10 g / 10 min measured at 230℃ under a load of 2.16 kg. The melt flow rate can be measured according to ASTM D1238-13.

[0021] Preferably, the random copolymer polypropylene in the adhesive and the random copolymer polypropylene in the maleic anhydride grafting product independently have a melting point of 140-160℃. The melting point can be measured by DSC.

[0022] More preferably, the random copolymer polypropylene in the adhesive has a melt flow rate of 0.2-0.5 g / 10 min measured at 230℃ under a load of 2.16 kg and a melting point of 143-146℃. The use of this random copolymer polypropylene results in an adhesive with better performance.

[0023] Preferably, the random copolymer polypropylene in the adhesive and the random copolymer polypropylene in the maleic anhydride grafting product independently are copolymers of propylene monomers and ethylene monomers; the mass ratio of the propylene monomers to the ethylene monomers is (95-98):(2-5).

[0024] Preferably, the polyolefin elastomer in the adhesive and the polyolefin elastomer in the maleic anhydride grafting product independently are at least one of ethylene-octene copolymers and ethylene-butene copolymers.

[0025] Preferably, the polyolefin elastomer in the adhesive and the polyolefin elastomer in the maleic anhydride grafting product independently have a melt flow rate of 0.5-2 g / 10 min measured at 190℃ under a load of 2.16 kg. The melt flow rate can be measured according to ASTM D1238-13.

[0026] Preferably, the maleic anhydride grafting product has a melt flow rate of 4-8 g / 10 min measured at 230℃ under a load of 0.325 kg. The melt flow rate can be measured according to ASTM D1238-13.

[0027] Preferably, the maleic anhydride grafting product has a melting point of 142-155℃. The melting point can be measured by DSC.

[0028] Preferably, the maleic anhydride grafting product has a residual maleic anhydride monomer content of 0.01wt%-0.025wt%; more preferably 0.015wt%-0.025wt%; and further preferably 0.018wt%-0.020wt%.

[0029] Preferably, the maleic anhydride grafting product has a maleic anhydride grafting rate of 0.70wt%-0.90wt%.

[0030] The maleic anhydride grafting rate of the maleic anhydride graft refers to the percentage of the maleic anhydride groups in the maleic anhydride graft in the mass of the maleic anhydride graft.

[0031] The maleic anhydride grafting rate of the maleic anhydride graft can be measured by acid-base titration. The specific process can be as follows: 5 g of the maleic anhydride graft is dissolved in 500 ml of dimethylbenzene at 120°C, then cooled to room temperature and added with acetone to precipitate the maleic anhydride graft from the solution, and the residue is filtered to obtain the filter residue, which is the maleic anhydride graft with the residual maleic anhydride monomers removed. Then, the filter residue is dried in an oven, and the dried filter residue is dissolved in dimethylbenzene at 120°C as the test solution. The test solution is titrated with 0.1 mol / L KOH / isopropyl alcohol solution at 120°C. After calculation, the maleic anhydride grafting rate of the maleic anhydride graft is obtained. The calculation formula of the maleic anhydride grafting rate of the maleic anhydride graft is (c / d) x 100%; wherein c is the mass of the maleic anhydride groups in the maleic anhydride graft calculated after titration, and d is the mass of the maleic anhydride graft after the residual maleic anhydride monomers are removed.

[0032] Preferably, the maleic anhydride graft is prepared as follows: the maleic anhydride monomer, the initiator and anhydrous ethanol are premixed in a mass ratio of 1:(0.12-0.18):(0.5-2) to obtain a premix; then the premix and the random copolymerized polypropylene and the polyolefin elastomer are mixed, and then melt extruded, granulated, and purified to obtain the maleic anhydride graft.

[0033] More preferably, the mass ratio of the maleic anhydride monomer, the random copolymerized polypropylene and the polyolefin elastomer is (1-1.5):(75-90):(10-25).

[0034] More preferably, the initiator comprises a peroxide initiator and N,N-dimethylformamide in a mass ratio of 1:(0.5-1).

[0035] Further preferably, the peroxide initiator is at least one of 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane, dicumyl peroxide or 2,4-di-tert-butylperoxyisopropylbenzene.

[0036] More preferably, the temperature of the melt extrusion is 90-200°C; the screw length-diameter ratio of the extruder for the melt extrusion is 45-50:1, and the screw rotation speed is 400-500 rpm.

[0037] More preferably, the purification process is as follows: the granules obtained after granulation are placed in an imidazole aqueous solution with a concentration of 0.1-0.5 wt%, and stirred at 80-95°C for 2-4 hours.

[0038] More preferably, the purification further comprises a drying step.

[0039] Preferably, the nano-inorganic filler is at least one of nano-silica, nano-alumina or nano-calcium carbonate.

[0040] Preferably, the nano-inorganic filler has an average particle size of 25-120 nm.

[0041] More preferably, the nano-inorganic filler has an average particle size of 25-35 nm, and further preferably 28-32 nm.

[0042] The average particle size of the nano-inorganic filler is controlled, and the obtained adhesive has better performance.

[0043] In the present application, the average particle size of the nano-inorganic filler is measured by transmission electron microscopy.

[0044] Preferably, the tackifier is at least one of terpene resin or C5 petroleum resin.

[0045] Preferably, the adhesive further comprises other auxiliary agents 0.5-4 parts; specifically, 0.5, 0.8, 1, 1.5, 2, 2.5, 3, 3.5, 4 parts by weight.

[0046] More preferably, the other auxiliary agent is at least one of a lubricant or an antioxidant.

[0047] Generally, in the adhesive, the amount of lubricant is 0.5-2.5 parts, and the amount of antioxidant is 0.5-1.5 parts.

[0048] Further preferably, the lubricant is at least one of polyethylene wax or silicone.

[0049] Further preferably, the antioxidant is at least one of a primary antioxidant or a secondary antioxidant.

[0050] Further preferably, the mass ratio of the primary antioxidant to the secondary antioxidant is 1: (1-2).

[0051] Further preferably, the primary antioxidant is at least one of antioxidant 1010, antioxidant 1076, antioxidant 1098, or antioxidant 1024.

[0052] Further preferably, the secondary antioxidant is at least one of antioxidant 168 or antioxidant DSTDP.

[0053] The preparation method of the above-mentioned adhesive comprises the following steps: mixing the components, melt extruding, and granulating, to obtain the adhesive.

[0054] Preferably, the melt extrusion temperature is 170-190℃; the screw length-diameter ratio of the melt extrusion extruder is 45-50:1, and the screw rotation speed is 300-500rpm.

[0055] The application of the adhesive in preparing an automobile cooling pipe is also within the protection scope of the present application.

[0056] An automobile cooling pipe comprising a nylon layer and a polypropylene layer, which are bonded by the adhesive.

[0057] Compared with the prior art, the present application has the following advantages: The adhesive obtained by the cooperation of the random copolymerized polypropylene, the polyolefin elastomer, the maleic anhydride graft, the nano inorganic filler and the tackifier has good (initial) peeling strength, good peeling strength under high temperature and cooling liquid immersion, and good durability, and is very suitable for preparing automobile cooling system composite nylon cooling pipes which need to bond PA and PP. DETAILED DESCRIPTION

[0058] In order to more clearly and completely describe the technical solutions of the present application, the present application is further described in detail below through specific examples, and it should be understood that the specific examples described herein are only used to explain the present application and are not used to limit the present application, and various changes can be made within the scope of the present application.

[0059] Some reagents selected by the embodiments and comparative examples of the present application are described as follows: Random copolymerized polypropylene 1#: PPR-4220 of Maoming Petrochemical, the melt flow rate is 0.3g / 10min, the test standard is ASTM D1238-13, the test condition is 230℃, 2.16Kg; the melting point is 145℃; Random copolymerized polypropylene 2#: SM198 of Maoming Petrochemical, the melt flow rate is 1.2g / 10min, the test standard is ASTM D1238-13, the test condition is 230℃, 2.16Kg; the melting point is 155℃; Homopolymerized polypropylene: L5E89 of Sichuan Petrochemical, the melt flow rate is 3.5g / 10min, the test standard is ASTM D1238-13, the test condition is 230℃, 2.16Kg; the melting point is 165℃; Ternary copolymerized polypropylene: FL7632L, the melt flow rate is 7g / 10min, the test standard is ASTM D1238-13, the test condition is 230℃, 2.16Kg; the melting point is 130℃, the manufacturer is TPC Company of Singapore Polyolefin elastomer 1#: POE ENGAGE 8842, C8 elastomer, DOW Chemical, melt flow rate 1.0 g / 10 min measured at 190 °C, 2.16 kg; Polyolefin elastomer 2#: POE ENGAGE 7467, C4 elastomer, DOW Chemical, melt flow rate 1.0 g / 10 min measured at 190 °C, 2.16 kg; Maleic anhydride: commercially available; Maleic anhydride graft 1#: self-made, process as follows: maleic anhydride, initiator (a mixture of 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane and N,N-dimethylformamide with a mass ratio of 1:1), anhydrous ethanol were premixed in a ratio of 1:0.15:1 to obtain a premix; then the premix and the random copolymerized polypropylene 1#, polyolefin elastomer 1# (wherein the mass ratio of maleic anhydride, random copolymerized polypropylene 1#, polyolefin elastomer 1# is 1.2:80:20) were added into a high-speed mixer for further mixing and dispersion, and then melt-extruded by a twin-screw extruder (the temperature of each zone was 90 °C, 130 °C, 150 °C, 170 °C, 175 °C, 185 °C, 190 °C, 190 °C, 190 °C, 190 °C, 200 °C, 200 °C, respectively; the screw length-diameter ratio was 48:1, and the screw rotation speed was 450 rpm) and cut into particles under water, and then placed in a 0.1 wt% imidazole aqueous solution, heated and stirred at 80 °C (denoted as temperature T) for 4 h (denoted as time t), and then dried for 6 h to obtain the maleic anhydride graft 1#. The maleic anhydride graft rate of the maleic anhydride graft 1# was 0.85% (measured by acid-base titration), the residual maleic anhydride content was 0.019%, the melt flow rate was 5.5 g / 10 min (230 °C, 0.325 kg), and the melting point was 144 °C; Maleic anhydride graft 2#: self-made, the difference from the maleic anhydride graft 1# was that the random copolymerized polypropylene 1# was replaced by the random copolymerized polypropylene 2#, and the polyolefin elastomer 1# was replaced by the polyolefin elastomer 2#; the mass ratio of maleic anhydride, random copolymerized polypropylene 2#, polyolefin elastomer 2# was 1.2:85:15; the maleic anhydride graft rate of the maleic anhydride graft 2# was 0.83%, the residual maleic anhydride content was 0.025%, the melt flow rate was 7.8 g / 10 min (230 °C, 0.325 kg), and the melting point was 154 °C; Maleic anhydride graft 3#: self-made, the difference from the maleic anhydride graft 1# was that the temperature T was 95 °C, and the time t was 2 h. The maleic anhydride graft rate of the maleic anhydride graft 3# was 0.84%, the residual maleic anhydride content was 0.016%, the melt flow rate was 5.5 g / 10 min (230 °C, 0.325 kg), and the melting point was 144 °C; Maleic anhydride graft 4#: self-made, the difference from maleic anhydride graft 1# is that the temperature T is 60℃ and the time t is 4h. The maleic anhydride grafting rate of maleic anhydride graft 4# is 0.84%, the residual maleic anhydride content is 0.045%, the melt flow rate is 5.5g / 10min (230℃, 0.325kg), and the melting point is 144℃; Maleic anhydride graft 5#: self-made, the difference from maleic anhydride graft 1# is that the random copolymer polypropylene 1# is replaced by homopolymer polypropylene. The maleic anhydride grafting rate of maleic anhydride graft 5# is 0.78%, the residual maleic anhydride content is 0.02%, the melt flow rate is 6.4g / 10min (230℃, 0.325kg), and the melting point is 165℃; Maleic anhydride graft 6#: self-made, the difference from maleic anhydride graft 1# is that the random copolymer polypropylene 1# is replaced by terpolymer polypropylene. The maleic anhydride grafting rate of maleic anhydride graft 6# is 0.85%, the residual maleic anhydride content is 0.019%, the melt flow rate is 8.1g / 10min (230℃, 0.325kg), and the melting point is 130℃; Maleic anhydride graft 7#: self-made, the difference from maleic anhydride graft 1# is that the polyolefin elastomer 1# is not added and the mass ratio of maleic anhydride and random copolymer polypropylene 1# is adjusted to 1.2:100. The maleic anhydride grafting rate of maleic anhydride graft 7# is 0.72%, the residual maleic anhydride content is 0.035%, the melt flow rate is 10.3g / 10min (230℃, 0.325kg), and the melting point is 145℃; Nano inorganic filler 1#: silica, CY-SP30, Zhejiang Jiupeng, the average particle size is 30nm; Nano inorganic filler 2#: silica, CY-SP100F, Zhejiang Jiupeng, the average particle size is 100nm; Micro inorganic filler: silica WL-1, 80 Yingchuang, the average particle size is 8μm; Tackifier 1#: terpene resin, T-100, Qunlin Chemical Industry, the melting point is ≥90℃; Tackifier 2#: terpene resin, T-120, Qunlin Chemical Industry, the melting point is ≥120℃; Other auxiliary agent 1#: antioxidant, including antioxidant 1010, antioxidant 168 and antioxidant DSTDP with a mass ratio of 1:1:0.5, commercially available; Other auxiliary agent 2#: lubricant, polyethylene wax, commercially available; If not specifically stated, each component (such as other auxiliary agent 1#) selected in each parallel example and comparative example is the same commercially available product.

[0060] The adhesives provided by the embodiments and comparative examples of the present application are tested for performance according to the following test methods: 1. Room temperature peel strength test: the adhesive is pressed into a sheet on a flat curing press at 180℃ for 10 min, with a pressure of 15Mpa, and the thickness of the sample sheet is 1mm. After being placed at room temperature for 24h, the sample is prepared according to the standard GB / T 2790-1995 (the process of sample preparation is as follows: PA (PA6 HY-2500, Jiangsu Haiyang), the sample sheet, and PP (PP T30S, Yanshan Petrochemical) are stacked in a three-layer structure from bottom to top, and placed in a high-temperature oven at 200℃ without pressure for 30 min), and the peel strength of PA and PP is tested at 180 degrees. 2. High-temperature aging peel strength test: the adhesive is pressed into a sheet on a flat curing press at 180℃ for 10 min, with a pressure of 15Mpa, and the thickness of the sample sheet is 1mm. The sample is prepared according to the standard GB / T 2790-1995 (the process of sample preparation is as follows: PA (PA6 HY-2500, Jiangsu Haiyang), the sample sheet, and PP (PP T30S, Yanshan Petrochemical) are stacked in a three-layer structure from bottom to top, and placed in a high-temperature oven at 200℃ without pressure for 30 min), and after being placed in an oven at 110℃ for 168h, the peel strength of PA and PP after high-temperature aging is tested at 180 degrees. The peel strength retention rate after high-temperature aging = (peel strength after aging) / (room temperature peel strength) x 100%. 3. Cooling liquid immersion peel strength test: the adhesive is pressed into a sheet on a flat curing press at 180℃ for 10 min, with a pressure of 15Mpa, and the thickness of the sample sheet is 1mm. The sample is prepared according to the standard GB / T 2790-1995 (the process of sample preparation is as follows: PA (PA6 HY-2500, Jiangsu Haiyang), the sample sheet, and PP (PP T30S, Yanshan Petrochemical) are stacked in a three-layer structure from bottom to top, and placed in a high-temperature oven at 200℃ without pressure for 30 min), and after being immersed in a cooling liquid (ethylene glycol-water solution, commercially available) for 96h, the peel strength of PA and PP after cooling liquid immersion is tested at 180 degrees. The peel strength retention rate after cooling liquid immersion = (peel strength after cooling liquid immersion) / (room temperature peel strength) x 100%. 4. Environmental stress cracking resistance (ESCR): after the adhesive sheet is cut and bent to a certain angle and immersed in a cooling liquid environment, it is aged at a constant temperature (50℃). According to the standard ASTM D1693, the surface of the sample is observed periodically to determine whether cracks have appeared, and the time of crack appearance is recorded.

[0061] The adhesives of the embodiments and comparative examples of the present application are prepared by the following preparation method: According to the ratio, the components are put into a high-speed mixing machine and mixed for 5 min, and the rotating speed of the mixing machine is 1000 r / min, to obtain a mixture; the mixture is extruded and granulated by a double-screw extruder, to obtain the adhesive; wherein the temperature of each zone of the double-screw extruder is set as 120℃, 150℃, 175℃, 185℃, 185℃, 190℃, 190℃, 190℃, 190℃, 200℃, the rotating speed is 300 r / min, and the length-diameter ratio of the screw is 48:1, to obtain the adhesive.

[0062] Examples 1-9 Examples 1-9 provide a series of adhesives, and the formula is shown in Table 1.

[0063] Table 1 Formula of Examples 1-9 (parts by weight) .

[0064] Comparative Examples 1-11 Comparative Examples 1-11 provide a series of adhesives, and the formula is shown in Table 2.

[0065] Table 2 Formula of Comparative Examples 1-11 (parts by weight)

[0066] The performance of the adhesives of each example and comparative example is determined according to the above-mentioned test methods, and the test results are shown in Table 3.

[0067] Table 3 Performance test results of the adhesives of each example and comparative example .

[0068] From Table 3, it can be seen that: The peel strength at room temperature of the adhesives of Examples 1-9 is all 98 N / m or more, the peel strength retention rate after high-temperature aging is all 86.1% or more, the peel strength retention rate after cooling liquid immersion is all 69.8% or more, and the environmental stress cracking resistance time is all 781 h or more, indicating that the peel strength of the adhesive of the present application is good, and the peel strength under high-temperature environment and cooling liquid immersion conditions can still be maintained well, and the durability is good, which is very suitable for preparing composite nylon cooling pipes which need to bond PA and PP.

[0069] In Comparative Example 1, homopolymer polypropylene is used to replace random copolymer polypropylene, and the peel strength test at room temperature, the peel strength retention under high temperature, and the durability of the obtained adhesive are poor or unsatisfactory.

[0070] In Comparative Example 2, terpolymer polypropylene is used to replace random copolymer polypropylene, and the peel strength retention of the obtained adhesive under cooling liquid immersion conditions is unsatisfactory, and the durability is poor.

[0071] The residual monomer content of the maleic anhydride graft of Comparative Example 3 is too high, and the properties of the adhesive obtained are poor or unsatisfactory.

[0072] The random copolymer polypropylene in the maleic anhydride graft of Comparative Example 4 is replaced by homopolymer polypropylene, and the properties of the adhesive obtained are poor or unsatisfactory.

[0073] The random copolymer polypropylene in the maleic anhydride graft of Comparative Example 5 is replaced by terpolymer polypropylene, and the retention of the peel strength of the adhesive obtained under the cooling liquid immersion condition is unsatisfactory, and the durability is poor.

[0074] The maleic anhydride graft of Comparative Example 6 is prepared without adding the polyolefin elastomer, and the properties of the adhesive obtained are poor or unsatisfactory.

[0075] Comparative Example 7 uses a micrometer-sized inorganic filler, and the retention of the peel strength of the adhesive obtained at high temperature is unsatisfactory, and the durability is poor.

[0076] Comparative Example 8 does not add the inorganic filler, and the properties of the adhesive obtained are poor or unsatisfactory.

[0077] Comparative Example 9 does not add the tackifier, and the peel strength of the adhesive obtained at room temperature is unsatisfactory, and the durability is poor.

[0078] Comparative Example 10 does not add the random copolymer polypropylene and the polyolefin elastomer, but instead uses an equal amount of the maleic anhydride graft to replace them, and the retention of the peel strength of the adhesive obtained at high temperature and the retention of the peel strength of the adhesive obtained under the cooling liquid immersion condition are both unsatisfactory, and the durability is also poor.

[0079] Comparative Example 11 does not add the maleic anhydride graft, but instead uses an equal amount of the random copolymer polypropylene and the polyolefin elastomer to replace it, and the peel strength of the adhesive obtained is poor, and the peel strength cannot be maintained at high temperature or under the cooling liquid immersion condition.

[0080] Obviously, the above-mentioned embodiments of the present application are merely examples for clearly illustrating the present application, and are not intended to limit the implementation modes of the present application. Based on the above-mentioned description, other different forms of changes or variations can also be made by those skilled in the art. Here, it is not necessary and also impossible to exhaust all the implementation modes. Any modification, equivalent replacement and improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the claims of the present application.

Claims

1. An adhesive, characterized in that, The components include the following parts by weight: 30-50 parts of random copolymer polypropylene 10-25 parts of polyolefin elastomer 15-41 parts of maleic anhydride graft 5-10 parts of nano-inorganic filler 3-10 parts of tackifier The maleic anhydride graft is a polymer obtained by reacting random copolymer polypropylene, polyolefin elastomer and maleic anhydride. The residual maleic anhydride monomer content in the maleic anhydride graft is ≤0.03wt%.

2. The adhesive according to claim 1, characterized in that, The random copolymer polypropylene in the adhesive and the random copolymer polypropylene in the maleic anhydride graft were independently measured at 230°C and 2.16 kg, and the melt flow rate was 0.2~10 g / 10 min.

3. The adhesive according to claim 1, characterized in that, The polyolefin elastomer in the adhesive and the polyolefin elastomer in the maleic anhydride graft are independently at least one of ethylene-octene copolymer and ethylene-butene copolymer.

4. The adhesive according to claim 1, characterized in that, The melt flow rate of the maleic anhydride graft measured at 230°C and 0.325 kg was 4~8 g / 10 min.

5. The adhesive according to claim 1, characterized in that, The melting point of the maleic anhydride graft is 142~155℃.

6. The adhesive according to claim 1, characterized in that, The tackifier is at least one of terpene resin or C5 petroleum resin; and / or The average particle size of the nano-inorganic filler is 25~120nm; and / or The nano-inorganic filler is at least one of nano-silica, nano-alumina, or nano-calcium carbonate.

7. The adhesive according to claim 1, characterized in that, The adhesive also includes 0.5 to 4 parts of other additives.

8. A method for preparing the adhesive according to any one of claims 1 to 7, characterized in that, The process includes the following steps: mixing the components, melting and extruding, and granulating to obtain the adhesive.

9. The use of the adhesive according to any one of claims 1 to 7 in the preparation of automotive cooling pipes.

10. An automotive cooling pipe, characterized in that, It includes a nylon layer and a polypropylene layer, said nylon layer and polypropylene layer being bonded together by the adhesive of any one of claims 1 to 7.

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