High-temperature-resistant hot melt adhesive special for bonding pp and pe and application thereof

Abstract

The present application relates to a kind of high-temperature-resistant hot melt adhesive dedicated to bonding PP and PE and its application.The hot melt adhesive is designed by the double-end modification of functionalized olefin block copolymer (OBC), and introduces polar groups according to the characteristics of PE and PP segments, respectively, combined with the synergistic effect of chain extender, tackifying resin and other additives, which significantly improves the interfacial bonding strength and high-temperature resistance of PP and PE.The middle layer of hot melt adhesive can be compounded with PP-R and PE-RT pipe materials through a three-layer co-extrusion process to form a stable multi-layer structure suitable for pipeline systems in high temperature and high pressure environments.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of hot melt adhesive, in particular to a high-temperature-resistant hot melt adhesive specially used for bonding PP and PE and application thereof. BACKGROUND

[0002] Polyethylene (PE) material and polypropylene (PP) material have poor compatibility, and the two cannot be directly fused together. When a plastic product with a multi-layer composite structure needs to be produced (for example, a frost resistance composite pipe with a PP-R outer layer and a PE-RT inner layer), a suitable hot melt adhesive is needed to have good bonding force with both polyethylene (PE) and polypropylene (PP). At present, the materials used for bonding polyethylene (PE) or polypropylene (PP) mainly select polyethylene or polypropylene as the base resin, graft modify the same, and increase the functional groups with bonding properties, such as maleic anhydride grafts or acrylate grafts.

[0003] However, the hot melt adhesive of the maleic anhydride graft or the acrylate graft system has good connection with polyethylene or polypropylene, but mainly depends on the base resin. At present, the existing hot melt adhesive has good bonding property with polyethylene, but has poor bonding property with polypropylene; the hot melt adhesive with good bonding property with polypropylene has poor bonding property with polyethylene.

[0004] Therefore, a hot melt adhesive capable of having excellent bonding force with both PE and PP is needed. SUMMARY

[0005] The technical purpose of the present application is to solve the problems in the background art and provide a high-temperature-resistant hot melt adhesive specially used for bonding PP and PE.

[0006] The above technical purpose of the present application is achieved by the following technical scheme:

[0007] A high-temperature-resistant hot melt adhesive specially used for bonding PP and PE, comprising the following preparation process:

[0008] Step S1: design of hot melt adhesive PE end layer functionalized OBC formula: the PE end layer raw material comprises olefin block copolymer OBC, maleic anhydride MAH, initiator, and functional modifier A;

[0009] Step S2: design of hot melt adhesive PP end layer functionalized OBC formula: the PP end layer raw material comprises olefin block copolymer OBC, acrylic acid AA, initiator, and functional modifier B;

[0010] Step S3: extrusion of high-temperature-resistant hot melt adhesive PE end layer and PP end layer: the raw materials of step S1 and step S2 are co-extruded under a specific process to obtain the high-temperature-resistant hot melt adhesive specially used for bonding PP and PE, and the extruder is a double-screw extruder.

[0011] As preferred, in the formula of the hot melt adhesive PE end layer of step S1, the initiator is dicumyl peroxide DCP, and the functional modifier A is glycidyl methacrylate GMA.

[0012] As preferred, in the component design of the hot melt adhesive PE end layer, the mass fraction of the initiator DCP is 0.3-1.0 parts, the mass fraction of maleic anhydride MAH is 3-8 parts, the mass fraction of the functional modifier A is 1-3 parts, the rest is olefin block copolymer OBC, and the total mass fraction of the PE end layer is 100 parts.

[0013] The application has the advantages that maleic anhydride MAH is a polar monomer containing anhydride groups, which is used to graft and introduce carboxylic acid groups (-COOH) to improve the polarity of OBC and enhance the compatibility with pipe materials; DCP is used as the initiator to generate active sites to promote the grafting of MAH and GMA; GMA is selected as the functional modifier A, the epoxy groups of which can react with the anhydride of MAH or the subsequent hydrolysis product (-COOH) to form a crosslinked network or a co-grafting structure, thereby improving the grafting rate of MAH and the surface compatibility of the material.

[0014] As preferred, in the formula of the hot melt adhesive PP end layer of step S2, the initiator is dicumyl peroxide DCP, and the functional modifier B is divinylbenzene DVB.

[0015] In the component design of the hot melt adhesive PP end layer, the mass fraction of acrylic acid AA is 3-6 parts, the mass fraction of the initiator DCP is 0.5-1 part, the mass fraction of the functional modifier B is 0.3-1 part, the rest is olefin block copolymer OBC, and the total mass fraction of the PP end layer is 100 parts.

[0016] Further, 0.1-0.3 parts of antioxidant can be added in the component design of the hot melt adhesive PP end layer.

[0017] The application has the advantages that acrylic acid AA is very suitable for grafting to the PP segment (the tertiary carbon hydrogen of PP is more prone to generate free radicals), and the use amount of DVB is controlled at <1 wt% to avoid excessive crosslinking and material embrittlement caused by excessive amount; and the addition of appropriate amount of antioxidant can avoid the degradation of the PP segment caused by long-term high-temperature exposure.

[0018] As preferred, step S3 adopts segmented temperature control and gradient grafting melt grafting extrusion; the extrusion process adopts a co-rotating twin-screw extruder, which can realize multi-zone temperature control and is provided with a side feeding port.

[0019] As preferred, the PE end layer raw material extrusion process is as follows:

[0020] The feeding zone temperature is controlled at 160-170℃, the OBC raw material is preliminarily pre-melted in the feeding zone after the maleic anhydride and GMA are premixed; the initiation reaction zone temperature is controlled at 180-190℃, the DCP initiator is fed into the initiation reaction zone, and the maleic anhydride and GMA blend are fed into the side feeding zone at the same time; the grafting reaction zone temperature is controlled at 170-175℃, the exhaust zone temperature is controlled at 160℃, and the cooling zone temperature is controlled at 140℃, and the unreacted monomers and by-products are removed by vacuum in the exhaust zone, and then cooled.

[0021] As preferred, the PP end layer raw material extrusion process is as follows:

[0022] The feeding zone temperature is 160℃; the initiation reaction zone is a high shear reaction zone, and the temperature is 180℃; the grafting reaction zone is 170℃; the exhaust zone is 150℃; the OBC raw material is fed into the feeding zone, the initiator is introduced into the initiation reaction zone, the acrylic acid and divinylbenzene are fed into the side feeding port after the initiator is introduced, and the functionalization grafting is completed in the grafting reaction zone.

[0023] By using the present application, the advantages are that the above-mentioned PE end layer and PP end layer raw material are subjected to temperature control and gradient grafting in the extrusion process, the PE and PP chains are activated respectively by temperature zoning, the grafting efficiency is improved, the risk of thermal degradation of the PP chains is reduced, and the mechanical properties of the material are retained; by controlling the monomer concentration and reaction time, the functional groups form a concentration gradient in the OBC molecular chain or the material body, and the interfacial compatibility is optimized.

[0024] As preferred, the raw material for the extrusion and granulation of the hot melt adhesive further comprises a chain extender, a dispersant, a plasticizer, a wetting agent and an adhesion resin, the adhesion resin uses a bio-based adhesion resin; the temperature zoning and feeding process of the extrusion and granulation of the hot melt adhesive are as follows:

[0025] Feeding zone: the temperature is controlled at 160℃, the PE end layer and PP end layer functionalized OBC are pre-melted in this zone;

[0026] Reaction zone 1: the temperature is controlled at 175-185℃, the PP end layer functionalized OBC reacts with the chain extender;

[0027] Reaction zone 2: the temperature is controlled at 165-175℃, the PE end layer functionalized OBC reacts with the chain extender; the reaction zone 1 and the reaction zone 2 are respectively provided with a side feeding port to feed the bio-based adhesion resin and the plasticizer;

[0028] Homogenization zone: the temperature is controlled at 160-170℃, the dispersant, the wetting agent and the above-mentioned filler are uniformly dispersed in this zone;

[0029] Die: the die temperature is controlled at 150-160℃ to ensure stable discharge; finally, the extrusion product is cut and granulated to obtain the hot melt adhesive.

[0030] As preferred, the chain extender adopts an epoxy-functionalized acrylic copolymer, the dispersant adopts silane coupling agent KH550, the plasticizer adopts a combination of sodium stearate and dialkyl sodium sulfate, and the wetting agent adopts a combination of sodium stearate and dialkyl sodium sulfate.

[0031] As preferred, in the hot melt adhesive, the mass fraction of the PP end layer functionalized OBC is 25-35 parts, the mass fraction of the PE end layer functionalized OBC is 35-45 parts, the chain extender is 0.1-1 part, the dispersant is 0.1-0.5 part, the plasticizer is 0.01-1 part, the wetting agent is 1-5 parts, and the rest is a bio-based tackifying resin.

[0032] Further, in application, the high-temperature-resistant hot melt adhesive specially used for bonding PP and PE is used for three-layer co-extrusion of PP-R and PE-RT with the hot melt adhesive and an auxiliary agent synchronously, so that PE and PP pipes bonded by the hot melt adhesive are prepared.

[0033] As preferred, when the hot melt adhesive is used for preparing pipes from PP-R and PE-RT materials, the mass fraction of the hot melt adhesive is preferably 40-60 parts, the mass fraction of the PP-R raw material is 30-50 parts, and the mass fraction of the PE-RT raw material is 10-15 parts.

[0034] As preferred, in use, the high-temperature-resistant hot melt adhesive specially used for bonding PP and PE is used for three-layer co-extrusion of PE-RY and PP-R special resins for pipes, and 1-5 parts of an antioxidant is added in the extrusion process, so that a high-strength temperature-resistant product is prepared.

[0035] The outer layer is a PP-R layer, the extrusion parameters are 200 DEG C for a feeding zone, 230-240 DEG C for a melting zone, and 220 DEG C for a die head;

[0036] The middle layer is a hot melt adhesive layer, the extrusion parameters are 160 DEG C for a feeding zone, 170-180 DEG C for a melting zone, and 195 DEG C for a die head;

[0037] The inner layer is a PE-RT layer, the extrusion parameters are 180 DEG C for a feeding zone, 200-210 DEG C for a melting zone, and 165 DEG C for a die head.

[0038] As preferred, the hot melt adhesive is proportioned with PP and PE, and is applied to the production of temperature-resistant and pressure-resistant composite pipes of the multi-layer composite structure of plastic products with an outer PP-R layer and an inner PE-RT layer.

[0039] By using the present application, the subsequent process can also follow the segmented temperature control process, and the processing window of PP-R high temperature and PE-RT medium temperature can be matched.

[0040] In summary, the present application has the following beneficial effects:

[0041] Double-end functional design: Maleic anhydride (MAH) is grafted on the PE end to introduce anhydride groups, enhancing chemical bonding with PE-RT; acrylic acid (AA) is grafted on the PP end to introduce carboxylic acid groups, combined with divinylbenzene (DVB) crosslinking and ZnO dynamic crosslinking agent to improve physical entanglement and heat resistance with PP-R;

[0042] Gradient grafting and segmented temperature control process: Using a twin-screw extruder with segmented temperature control (PE end 170-190℃ / PP end 160-180℃), the different chain segment reaction sites are precisely activated to avoid degradation;

[0043] Multi-layer co-extrusion compatibility: The middle layer of hot melt adhesive has a melt viscosity between PP-R and PE-RT, and the interface bonding force is optimized by synchronous optimization of polar groups and chemical crosslinking, with a peel strength ≥4 N / mm;

[0044] High temperature and pressure resistance: This special hot melt adhesive can ensure that the pipe material does not delaminate and leak under long-term pressure test at room temperature and 95℃ high temperature. BRIEF DESCRIPTION OF DRAWINGS

[0045] Figure 1 is a process flow diagram of a special high-temperature hot melt adhesive for bonding PP and PE. DETAILED DESCRIPTION

[0046] The following specific examples are merely an explanation of the present application and are not a limitation of the present application. Those skilled in the art can make modifications to the present examples without creative contribution after reading the present specification, but as long as it is within the scope of the claims of the present application, it is protected by the patent law.

[0047] Example 1

[0048] Hot melt adhesive PE end layer functional OBC formula design: the mass fraction of initiator DCP is 0.3 parts, the mass fraction of maleic anhydride MAH is 3 parts, the mass fraction of functional modifier A is 1 part, and the rest is olefin block copolymer OBC.

[0049] Hot melt adhesive PP end layer functional OBC formula design: the mass fraction of acrylic acid AA is 3 parts, the mass fraction of initiator DCP is 0.5 parts, the mass fraction of functional modifier B is 0.3 parts, and 0.1 parts of antioxidant is further added, and the rest is olefin block copolymer OBC, and the total mass fraction of the PP end layer is 100 parts.

[0050] In step S3, the PE end layer and the PP end layer of the high-temperature hot melt adhesive are extruded,

[0051] The extrusion process parameters of the PE end layer are:

[0052] The temperature of the feeding zone is controlled at 160°C, the OBC raw material is preliminarily pre-melted in the feeding zone after the maleic anhydride and GMA are premixed; the temperature of the initiation reaction zone is controlled at 180°C, the DCP initiator is fed into the initiation reaction zone, and the maleic anhydride and GMA blend are fed into the side feeding zone at the same time; the temperature of the grafting reaction zone is controlled at 170°C, the temperature of the exhaust zone is controlled at 160°C, and the temperature of the cooling zone is controlled at 140°C, and the unreacted monomers and by-products are removed by vacuum in the exhaust zone, and then cooled.

[0053] The extrusion process parameters of the PP end layer are as follows:

[0054] The temperature of the feeding zone is 160°C; the temperature of the initiation reaction zone is 180°C, which is a high-shear reaction zone; the temperature of the grafting reaction zone is 170°C; the temperature of the exhaust zone is 150°C; the OBC raw material is fed into the feeding zone, the initiator is introduced into the initiation reaction zone, the acrylic acid and divinylbenzene are fed into the side feeding port after the initiator is introduced, and the functionalization grafting is completed in the grafting reaction zone.

[0055] Step S4: Extrusion granulation of the hot melt adhesive: in the hot melt adhesive, the mass fraction of the PP end layer functionalized OBC is 25 parts, the mass fraction of the PE end layer functionalized OBC is 35 parts, the mass fraction of the chain extender is 0.1 part, the mass fraction of the dispersing agent is 0.1 part, the mass fraction of the plasticizer is 0.01 part, the mass fraction of the wetting agent is 1 part, and the rest is bio-based tackifying resin; the extrusion process parameters of the hot melt adhesive are as follows:

[0056] Reaction zone 1: the temperature is controlled at 175°C, and the PP end layer functionalized OBC reacts with the chain extender;

[0057] Reaction zone 2: the temperature is controlled at 165°C, and the PE end layer functionalized OBC reacts with the chain extender; the reaction zone 1 and the reaction zone 2 are respectively provided with a side feeding port to feed the bio-based tackifying resin and the plasticizer;

[0058] Homogenization zone: the temperature is controlled at 160°C, and the dispersing agent, the wetting agent and the above-mentioned fillers are uniformly dispersed in this zone;

[0059] Die: the temperature of the die is controlled at 150°C to ensure stable discharge; finally, the extruded product is cut and granulated to obtain the hot melt adhesive.

[0060] Example 2

[0061] The formula design of the hot melt adhesive PE end layer functionalized OBC: the mass fraction of the initiator DCP is 1.0 part, the mass fraction of the maleic anhydride MAH is 8 parts, the mass fraction of the functionalization modifier A is 3 parts, and the rest is an olefin block copolymer OBC.

[0062] The functionalized OBC formula design of the hot melt adhesive PP end layer: the mass fraction of acrylic acid AA is 6 parts, the mass fraction of initiator DCP is 1 part, the mass fraction of functional modifier B is 1 part, 0.3 parts of antioxidant is further added, and the rest is olefin block copolymer OBC, and the total mass fraction of the PP end layer is 100 parts.

[0063] In step S3, the PE end layer and the PP end layer of the high-temperature-resistant hot melt adhesive are extruded,

[0064] The extrusion process parameters of the PE end layer are:

[0065] The feeding zone temperature is controlled at 170°C, the OBC raw material is preliminarily pre-melted in the feeding zone after the maleic anhydride and GMA are pre-mixed, the temperature in the initiation reaction zone is controlled at 190°C, the maleic anhydride and GMA blend are fed into the side feeding zone after the DCP initiator is fed into the initiation reaction zone, the temperature in the grafting reaction zone is controlled at 175°C, the temperature in the exhaust zone is controlled at 160°C, and the temperature in the cooling zone is controlled at 140°C, and the unreacted monomers and by-products are removed by vacuum in the exhaust zone after cooling.

[0066] The extrusion process parameters of the PP end layer are:

[0067] The feeding zone temperature is 160°C; the initiation reaction zone is a high-shear reaction zone with a temperature of 180°C; the grafting reaction zone is 170°C; the exhaust zone is 150°C; the OBC raw material is fed into the feeding zone, the acrylic acid and divinylbenzene are fed into the side feeding port after the initiator is introduced into the initiation reaction zone, and the functional grafting is completed in the grafting reaction zone.

[0068] In step S4, the hot melt adhesive is extruded and granulated: in the hot melt adhesive, the mass fraction of the PP end layer functionalized OBC is 35 parts, the mass fraction of the PE end layer functionalized OBC is 45 parts, the chain extender is 1 part, the dispersant is 0.5 parts, the plasticizer is 1 part, the wetting agent is 5 parts, and the rest is bio-based tackifying resin; the hot melt adhesive extrusion process parameters are:

[0069] Reaction zone 1: the temperature is controlled at 185°C, and the PP end layer functionalized OBC reacts with the chain extender;

[0070] Reaction zone 2: the temperature is controlled at 175°C, and the PE end layer functionalized OBC reacts with the chain extender; the reaction zone 1 and the reaction zone 2 are respectively provided with a side feeding port to feed the bio-based tackifying resin and the plasticizer;

[0071] Homogenization zone: the temperature is controlled at 170°C, and the dispersant, the wetting agent and the above fillers are uniformly dispersed in this zone;

[0072] Die: the die temperature is controlled at 160°C to ensure stable discharge; finally, the extruded product is cut and granulated to obtain the hot melt adhesive.

[0073] Example 3

[0074] Hot melt adhesive PE end layer functional OBC formula design: the mass fraction of initiator DCP is 0.3 parts, the mass fraction of maleic anhydride MAH is 3 parts, the mass fraction of functional modifier A is 1 part, and the rest is olefin block copolymer OBC.

[0075] Hot melt adhesive PP end layer functional OBC formula design: the mass fraction of acrylic acid AA is 6 parts, the mass fraction of initiator DCP is 1 part, the mass fraction of functional modifier B is 1 part, 0.3 parts of antioxidant is further added, and the rest is olefin block copolymer OBC, and the total mass fraction of the PP end layer is 100 parts.

[0076] In step S3, the PE end layer and the PP end layer of the high-temperature resistant hot melt adhesive are extruded,

[0077] The extrusion process parameters of the PE end layer are:

[0078] The temperature of the feeding zone is controlled at 160℃, the OBC raw material is preliminarily pre-melted in the feeding zone after the maleic anhydride and GMA are pre-mixed, the temperature of the initiation reaction zone is controlled at 180℃, the maleic anhydride and GMA blend are fed into the side feeding zone after the DCP initiator is introduced into the initiation reaction zone, the temperature of the grafting reaction zone is controlled at 170℃, the temperature of the exhaust zone is controlled at 160℃, and the temperature of the cooling zone is controlled at 140℃. After the unreacted monomers and by-products are removed by vacuum in the exhaust zone, cooling is performed.

[0079] The extrusion process parameters of the PP end layer are:

[0080] The temperature of the feeding zone is 160℃; the temperature of the initiation reaction zone is 180℃, which is a high-shear reaction zone; the temperature of the grafting reaction zone is 170℃; the temperature of the exhaust zone is 150℃; the OBC raw material is introduced into the feeding zone, the initiator is introduced into the initiation reaction zone, the acrylic acid and divinylbenzene are fed into the side feeding port, and the functional grafting is completed in the grafting reaction zone.

[0081] In step S4, the hot melt adhesive is extruded and granulated: in the hot melt adhesive, the mass fraction of the PP end layer functional OBC is 25 parts, the mass fraction of the PE end layer functional OBC is 35 parts, the mass fraction of the chain extender is 0.1 part, the mass fraction of the dispersing agent is 0.1 part, the mass fraction of the plasticizer is 0.01 part, the mass fraction of the wetting agent is 1 part, and the rest is bio-based tackifying resin; the hot melt adhesive extrusion process parameters are:

[0082] Reaction zone 1: the temperature is controlled at 175℃, and the PP end layer functional OBC reacts with the chain extender;

[0083] Reaction zone 2: the temperature is controlled at 170℃, and the PE end layer functional OBC reacts with the chain extender; the reaction zone 1 and the reaction zone 2 are respectively provided with a side feeding port to feed the bio-based tackifying resin and the plasticizer;

[0084] Homogenization zone: the temperature is controlled at 160℃, the dispersant, wetting agent and the above-mentioned filler are put in this zone to uniformly disperse;

[0085] Die head: the die head temperature is controlled at 150℃ to ensure stable discharge; finally, the extruded product is cut and granulated to obtain the hot melt adhesive.

[0086] Example 4

[0087] Functional OBC formula design of PE end layer of hot melt adhesive: the mass fraction of initiator DCP is 1.0 part, the mass fraction of maleic anhydride MAH is 8 parts, the mass fraction of functional modifier A is 3 parts, and the rest is olefin block copolymer OBC.

[0088] Functional OBC formula design of PP end layer of hot melt adhesive: the mass fraction of acrylic acid AA is 3 parts, the mass fraction of initiator DCP is 0.5 parts, the mass fraction of functional modifier B is 0.3 parts, 0.1 parts of antioxidant is further added, and the rest is olefin block copolymer OBC, and the total mass fraction of the PP end layer is 100 parts.

[0089] In step S3, the extrusion of the high-temperature-resistant hot melt adhesive PE end layer and the PP end layer,

[0090] The extrusion process parameters of the PE end layer are:

[0091] The temperature of the feeding zone is controlled at 170℃, the OBC raw material is preliminarily pre-melted in the feeding zone after the maleic anhydride and GMA are pre-mixed, the temperature of the initiation reaction zone is controlled at 190℃, the maleic anhydride and GMA blend are fed into the side feeding zone after the DCP initiator is put into the initiation reaction zone, the temperature of the grafting reaction zone is controlled at 175℃, the temperature of the exhaust zone is controlled at 160℃, and the temperature of the cooling zone is controlled at 140℃, and after the unreacted monomers and by-products are removed by vacuum in the exhaust zone, cooling is performed.

[0092] The extrusion process parameters of the PP end layer are:

[0093] The temperature of the feeding zone is 160℃; the temperature of the initiation reaction zone is 180℃, which is a high-shear reaction zone; the temperature of the grafting reaction zone is 170℃; the temperature of the exhaust zone is 150℃; the OBC raw material is fed into the feeding zone, the initiator is introduced into the initiation reaction zone, the acrylic acid and divinylbenzene are fed into the side feeding port, and the functional grafting is completed in the grafting reaction zone.

[0094] Step S4: extrusion and granulation of the hot melt adhesive: in the hot melt adhesive, the mass fraction of the PP end layer functional OBC is 35 parts, the mass fraction of the PE end layer functional OBC is 45 parts, the mass fraction of the chain extender is 1 part, the mass fraction of the dispersant is 0.5 parts, the mass fraction of the plasticizer is 1 part, the mass fraction of the wetting agent is 5 parts, and the rest is bio-based tackifying resin; the hot melt adhesive extrusion process parameters are:

[0095] Reaction zone 1: temperature control at 185℃, PP end layer functionalized OBC reacts with chain extender;

[0096] Reaction zone 2: temperature control at 175℃, PE end layer functionalized OBC reacts with chain extender; reaction zone 1 and reaction zone 2 are respectively provided with side feeding ports to feed bio-based tackifying resin and plasticizer;

[0097] Homogenization zone: temperature control at 170℃, this zone is fed with dispersant, wetting agent and the above fillers for uniform dispersion;

[0098] Die: the die temperature is controlled at 160℃ to ensure stable discharge; finally, the extruded product is cut and granulated to obtain the hot melt adhesive.

[0099] Example 5

[0100] Hot melt adhesive PE end layer functionalized OBC formula design: the mass fraction of initiator DCP is 0.5 parts, the mass fraction of maleic anhydride MAH is 5 parts, the mass fraction of functional modifier A is 1.9 parts, and the rest is olefin block copolymer OBC.

[0101] Hot melt adhesive PP end layer functionalized OBC formula design: the mass fraction of acrylic acid AA is 5 parts, the mass fraction of initiator DCP is 0.8 parts, the mass fraction of functional modifier B is 0.4 parts, and further 0.2 parts of antioxidant is added, and the rest is olefin block copolymer OBC, and the total mass fraction of the PP end layer is 100 parts.

[0102] In step S3, the high-temperature-resistant hot melt adhesive PE end layer and PP end layer are extruded,

[0103] The extrusion process parameters of the PE end layer are:

[0104] The feeding zone temperature is controlled at 165℃, and after the maleic anhydride and GMA are premixed, the OBC raw material is preliminarily pre-melted in the feeding zone; the initiation reaction zone temperature is controlled at 185℃, and after the DCP initiator is fed in the initiation reaction zone, the maleic anhydride and GMA blend are fed in the side feeding zone; the grafting reaction zone temperature is controlled at 175℃, the exhaust zone temperature is controlled at 160℃, and the cooling zone temperature is controlled at 140℃, after the unreacted monomers and by-products are removed by vacuum in the exhaust zone, cooling is performed.

[0105] The extrusion process parameters of the PP end layer are:

[0106] The feeding zone temperature is 160℃; the initiation reaction zone is a high-shear reaction zone with a temperature of 180℃; the grafting reaction zone is 170℃; the exhaust zone is 150℃; the OBC raw material is fed in the feeding zone, the initiator is introduced after the initiation reaction zone, the acrylic acid and divinylbenzene are fed through the side feeding port, and the functionalization grafting is completed in the grafting reaction zone.

[0107] Step S4 extrusion granulation of hot melt adhesive: in the hot melt adhesive, the mass fraction of PP end layer functional OBC is 35 parts, the mass fraction of PE end layer functional OBC is 35 parts, the chain extender is 1 part, the dispersing agent is 0.5 parts, the plasticizer is 0.01 parts, the wetting agent is 3 parts, and the rest is bio-based tackifying resin; the hot melt adhesive extrusion process parameters are:

[0108] Reaction zone 1: the temperature is controlled at 185℃, the PP end layer functional OBC reacts with the chain extender;

[0109] Reaction zone 2: the temperature is controlled at 175℃, the PE end layer functional OBC reacts with the chain extender; reaction zone 1 and reaction zone 2 are respectively provided with a side feeding port to feed bio-based tackifying resin and plasticizer;

[0110] Homogenization zone: the temperature is controlled at 170℃, the dispersing agent, wetting agent and the above filler are uniformly dispersed in this zone;

[0111] Die: the die temperature is controlled at 160℃ to ensure stable discharge; finally, the extruded product is cut and granulated to obtain the hot melt adhesive.

[0112] Example 6

[0113] Hot melt adhesive PE end layer functional OBC formula design: the mass fraction of initiator DCP is 0.5 parts, the mass fraction of maleic anhydride MAH is 5 parts, the mass fraction of functional modifier A is 1.9 parts, and the rest is olefin block copolymer OBC.

[0114] Hot melt adhesive PP end layer functional OBC formula design: the mass fraction of acrylic acid AA is 5 parts, the mass fraction of initiator DCP is 0.8 parts, the mass fraction of functional modifier B is 0.4 parts, 0.2 parts of antioxidant is further added, and the rest is olefin block copolymer OBC, and the total mass fraction of PP end layer is 100 parts.

[0115] In step S3, the extrusion of the high-temperature-resistant hot melt adhesive PE end layer and PP end layer,

[0116] The extrusion process parameters of the PE end layer are:

[0117] The temperature of the feeding zone is controlled at 165℃, the OBC raw material is preliminarily pre-melted in the feeding zone after the maleic anhydride and GMA are pre-mixed; the temperature of the initiation reaction zone is controlled at 185℃, the DCP initiator is fed into the initiation reaction zone, and the maleic anhydride and GMA blend are fed into the side feeding zone at the same time; the temperature of the grafting reaction zone is controlled at 175℃, the temperature of the exhaust zone is controlled at 160℃, and the temperature of the cooling zone is controlled at 140℃; after the unreacted monomers and by-products are removed by vacuum in the exhaust zone, cooling is carried out.

[0118] The extrusion process parameters of the PP end layer are:

[0119] The temperature of the feeding zone is 160°C; the initiation reaction zone is a high shear reaction zone, the temperature of which is 180°C; the grafting reaction zone is 170°C; the exhaust zone is 150°C; the OBC raw material is fed into the feeding zone, the initiator is introduced after the initiation reaction zone, the acrylic acid and divinyl benzene are fed through the side feeding port, and the functionalization grafting is completed in the grafting reaction zone.

[0120] Step S4: extrusion granulation of the hot melt adhesive: in the hot melt adhesive, the mass fraction of the PP end layer functionalized OBC is 28 parts, the mass fraction of the PE end layer functionalized OBC is 40 parts, the chain extender is 0.8 parts, the dispersant is 0.4 parts, the plasticizer is 0.5 parts, the wetting agent is 2 parts, and the rest is the bio-based tackifying resin; the hot melt adhesive extrusion process parameters are as follows:

[0121] Reaction zone 1: the temperature is controlled at 175°C, and the PP end layer functionalized OBC reacts with the chain extender;

[0122] Reaction zone 2: the temperature is controlled at 175°C, and the PE end layer functionalized OBC reacts with the chain extender; reaction zone 1 and reaction zone 2 are respectively provided with a side feeding port to feed the bio-based tackifying resin and the plasticizer;

[0123] Homogenization zone: the temperature is controlled at 170°C, and the dispersant, the wetting agent and the above-mentioned filler are uniformly dispersed in this zone;

[0124] Die: the die temperature is controlled at 160°C to ensure stable discharge; finally, the extruded product is cut and granulated to obtain the hot melt adhesive.

[0125] Example 7

[0126] Hot melt adhesive PE end layer functionalized OBC formula design: the mass fraction of the initiator DCP is 0.5 parts, the mass fraction of the maleic anhydride MAH is 5 parts, the mass fraction of the functionalization modifier A is 1.9 parts, and the rest is the olefin block copolymer OBC.

[0127] Hot melt adhesive PP end layer functionalized OBC formula design: the mass fraction of the acrylic acid AA is 5 parts, the mass fraction of the initiator DCP is 0.8 parts, the mass fraction of the functionalization modifier B is 0.4 parts, 0.2 parts of antioxidant is further added, and the rest is the olefin block copolymer OBC, and the total mass fraction of the PP end layer is 100 parts.

[0128] In step S3 of extruding the high-temperature resistant hot melt adhesive PE end layer and PP end layer,

[0129] The extrusion process parameters of the PE end layer are as follows:

[0130] The temperature of the feeding zone is controlled at 165℃, the OBC raw material is preliminarily pre-melted in the feeding zone after the maleic anhydride and GMA are premixed; the temperature of the initiation reaction zone is controlled at 185℃, the DCP initiator is fed into the initiation reaction zone, and the maleic anhydride and GMA blend are fed into the side feeding zone at the same time; the temperature of the grafting reaction zone is controlled at 175℃, the temperature of the exhaust zone is controlled at 160℃, and the temperature of the cooling zone is controlled at 140℃, and the unreacted monomers and by-products are removed by vacuum in the exhaust zone, and then cooled.

[0131] The extrusion process parameters of the PP end layer are as follows:

[0132] The temperature of the feeding zone is 160℃; the temperature of the initiation reaction zone is 180℃, which is a high-shear reaction zone; the temperature of the grafting reaction zone is 170℃; the temperature of the exhaust zone is 150℃; the OBC raw material is fed into the feeding zone, the initiator is introduced into the initiation reaction zone, the acrylic acid and divinylbenzene are fed into the side feeding port, and the functionalization grafting is completed in the grafting reaction zone.

[0133] Step S4: Extrusion granulation of the hot melt adhesive: in the hot melt adhesive, the mass fraction of the PP end layer functionalized OBC is 30 parts, the mass fraction of the PE end layer functionalized OBC is 39 parts, the chain extender is 0.6 parts, the dispersant is 0.25 parts, the plasticizer is 0.63 parts, the wetting agent is 2.8 parts, and the rest is bio-based tackifying resin; the hot melt adhesive extrusion process parameters are as follows:

[0134] Reaction zone 1: the temperature is controlled at 180℃, and the PP end layer functionalized OBC reacts with the chain extender;

[0135] Reaction zone 2: the temperature is controlled at 170℃, and the PE end layer functionalized OBC reacts with the chain extender; the reaction zone 1 and the reaction zone 2 are respectively provided with a side feeding port to feed the bio-based tackifying resin and the plasticizer;

[0136] Homogenization zone: the temperature is controlled at 165℃, and the dispersant, the wetting agent and the above fillers are uniformly dispersed in this zone;

[0137] Die: the die temperature is controlled at 155℃ to ensure stable discharge; finally, the extrusion product is cut and granulated to obtain the hot melt adhesive.

[0138] Comparative Example 1

[0139] The common ordinary OBC hot melt adhesive on the market.

[0140] Comparative Example 2

[0141] Different from the above-mentioned Example 7, the PE end component is removed in this comparative example.

[0142] Comparative Example 3

[0143] Different from the above-mentioned Example 7, the PP end component is removed in this comparative example.

[0144] For the hot melt adhesives prepared in Examples 1-7 and Comparative Examples 1-3, the extrusion process is as follows:

[0145] The hot melt adhesive is 50 parts by mass, the PP-R raw material is 40 parts by mass, and the PE-RT raw material is 10 parts by mass;

[0146] The outer layer is a PP-R layer, the extrusion parameters are 200°C for the feeding zone, 235°C for the melting zone, and 220°C for the die; the middle layer is a hot melt adhesive layer, the extrusion parameters are 160°C for the feeding zone, 175°C for the melting zone, and 195°C for the die; and the inner layer is a PE-RT layer, the extrusion parameters are 180°C for the feeding zone, 205°C for the melting zone, and 165°C for the die.

[0147] The long-term test at 95°C under hydrostatic pressure test (stop when delamination or leakage occurs) is tested respectively; in addition, the peel strength of the extruded adhesive PP, PE pipe material, and the temperature resistance (the temperature at which the product starts to soften) are tested.

[0148] The test results of Examples 1-7 and Comparative Examples 1-3 are shown in Table 1 below:

[0149] Table 1 Test Results

[0150]

[0151] As can be seen from the table:

[0152] In the data results of Examples 1-4, since the end values of the process parameters are used, the parameters are not suitable, and therefore the adhesion of the hot melt adhesive prepared to PP and PE, the material temperature resistance and pressure test results are not as good as Examples 5-7;

[0153] In Example 5, the process parameters of the two end layers are optimized, and on this basis, the performance of the hot melt adhesive product prepared is better than Examples 1-4, but compared with the following examples, it can be concluded that the ratio of the hot melt adhesive and the process parameter design still need to be optimized;

[0154] Examples 6-7, compared to the process conditions of Example 7, the functional modified hot melt adhesive prepared has the best adhesion to PP and PE, can reach 160°C in the temperature resistance test, and can last more than 5000h without delamination or leakage in the 95°C pressure test.

[0155] Compared with Examples 2-3, since Comparative Examples 2 and 3 do not use PP and PE end layer raw material process design, and do not use segmented temperature control and gradient grafting process during preparation, the hot melt adhesives prepared in Comparative Examples 2-3 are far inferior to Examples in adhesion, temperature resistance, and pressure resistance;

[0156] The comparative example 1 uses the ordinary OBC hot melt adhesive without any processing modification treatment for bonding, and the performance obtained is the worst. It can be concluded that the hot melt adhesive of the present application is significantly superior to the conventional scheme in terms of PP / PE dual-phase bonding strength, high temperature resistance and process compatibility, and is suitable for the manufacture of composite pipes under harsh working conditions.

Claims

1. A high temperature resistant hot melt adhesive specific for bonding PP and PE, characterized in that, The preparation process comprises the following steps: Step S1: functionalization of OBC formula design for PE end layer of hot melt adhesive: the PE end layer raw material comprises olefin block copolymer OBC, maleic anhydride MAH, initiator, and functionalization modifier A; Step S2: functionalization of OBC formula design for PP end layer of hot melt adhesive: the PP end layer raw material comprises olefin block copolymer OBC, acrylic acid AA, initiator, and functionalization modifier B; Step S3: extrusion of high-temperature-resistant hot melt adhesive PE end layer and PP end layer: the raw materials in steps S1 and S2 are co-extruded under specific processes to obtain the high-temperature-resistant hot melt adhesive specially used for bonding PP and PE, and a double-screw extruder is used as the extruder; In the formula of the PE end layer of the hot melt adhesive in step S1, the initiator is dicumyl peroxide DCP, and the functionalization modifier A is glycidyl methacrylate GMA; In the component design of the PE end layer of the hot melt adhesive, the mass fraction of the initiator DCP is 0.3-1.0 parts, the mass fraction of maleic anhydride MAH is 3-8 parts, the mass fraction of the functionalization modifier A is 1-3 parts, the rest is olefin block copolymer OBC, and the total mass fraction of the PE end layer is 100 parts; In the formula of the PP end layer of the hot melt adhesive in step S2, the initiator is dicumyl peroxide DCP, and the functionalization modifier B is divinylbenzene DVB; In the component design of the PP end layer of the hot melt adhesive, the mass fraction of acrylic acid AA is 3-6 parts, the mass fraction of the initiator DCP is 0.5-1 part, the mass fraction of the functionalization modifier B is 0.3-1 part, the mass fraction of the antioxidant is 0.1-0.3 part, the rest is olefin block copolymer OBC, and the total mass fraction of the PP end layer is 100 parts; In the hot melt adhesive, the mass fraction of the PP end layer functionalized OBC is 25-35 parts, the mass fraction of the PE end layer functionalized OBC is 35-45 parts, the mass fraction of the chain extender is 0.1-1 part, the mass fraction of the dispersing agent is 0.1-0.5 part, the mass fraction of the plasticizer is 0.01-1 part, the mass fraction of the wetting agent is 1-5 parts, and the rest is bio-based tackifying resin; The step S3 adopts segmented temperature control and gradient grafting melt grafting extrusion; the extrusion process adopts multi-zone temperature control of a co-rotating twin-screw extruder, and a side feeding port is arranged.

2. The high temperature resistant hot melt adhesive according to claim 1, wherein, The PE end layer raw material extrusion process is as follows: The temperature of the feeding zone is controlled at 160-170℃, the OBC raw material is preliminarily pre-melted in the feeding zone after the pre-mixing of maleic anhydride and GMA; the temperature of the initiation reaction zone is controlled at 180-190℃, the DCP initiator is fed into the initiation reaction zone, and the maleic anhydride and GMA blend are fed into the side feeding zone at the same time; the temperature of the grafting reaction zone is controlled at 170-175℃, the temperature of the exhaust zone is controlled at 160℃, and the temperature of the cooling zone is controlled at 140℃; after the unreacted monomers and by-products are removed by vacuum in the exhaust zone, cooling is performed.

3. The high temperature resistant hot melt adhesive according to claim 2, wherein, The PP end layer raw material extrusion process is as follows: The temperature of the feeding zone is 160℃; the temperature of the initiation reaction zone is 180℃; the temperature of the grafting reaction zone is 170℃; the temperature of the exhaust zone is 150℃; the OBC raw material is fed into the feeding zone, the initiator is introduced into the initiation reaction zone, the acrylic acid and divinyl benzene are fed into the grafting reaction zone through the side feeding port, and the functionalization grafting is completed in the grafting reaction zone.

4. The high temperature resistant hot melt adhesive according to claim 3, wherein, The raw material for the extrusion granulation of the hot melt adhesive further comprises a chain extender, a dispersant, a plasticizer, a wetting agent, and a tackifying resin, the tackifying resin is a bio-based tackifying resin, the temperature partition of the extrusion granulation of the hot melt adhesive and the feeding process are as follows: Reaction zone 1: the temperature is controlled at 175-185℃, the PP end layer functionalized OBC reacts with the chain extender; Reaction zone 2: the temperature is controlled at 165-175℃, the PE end layer functionalized OBC reacts with the chain extender; the reaction zone 1 and the reaction zone 2 are respectively provided with a side feeding port to feed the bio-based tackifying resin and the plasticizer; Homogenization zone: the temperature is controlled at 160-170℃, the dispersant, the wetting agent and the above-mentioned filler are uniformly dispersed in this zone; Die: the temperature of the die is controlled at 150-160℃ to ensure stable discharging; finally, the extrusion product is cut and granulated to obtain the hot melt adhesive.

5. The high temperature resistant hot melt adhesive according to claim 4, wherein, The chain extender is an epoxy functionalized acrylic acid copolymer, the dispersant is a silane coupling agent KH550, the plasticizer is a citric acid ester, and the wetting agent is a combination of sodium stearate and dialkyl sodium sulfate.

6. Use of a high temperature resistant hot melt adhesive specific for bonding PP and PE, characterized in that, In application, the PP-R and the PE-RT are subjected to three-layer co-extrusion with the hot melt adhesive of any one of claims 1-5 and the auxiliary agent synchronously, i.e. the PE and the PP pipe material bonded by the hot melt adhesive are prepared; When the hot melt adhesive is used to bond the PP-R and the PE-RT material to prepare pipe material, the mass fraction of the hot melt adhesive is 40-60 parts, the mass fraction of the PP-R raw material is 30-50 parts, and the mass fraction of the PE-RT raw material is 10-15 parts.

7. The use of a high temperature resistant hot melt adhesive specific for bonding PP and PE according to claim 6, characterized in that, The hot melt adhesive is subjected to three-layer co-extrusion with the PE-RY and the PP-R special resin for pipe material, 1-5 parts of antioxidant is added in the extrusion process, and a high-strength temperature-resistant product is prepared. The outer layer is a PP-R layer, the extrusion parameters are a feeding zone of 200℃, a melting zone of 230-240℃, and a die of 220℃; The middle layer is a hot melt adhesive layer, the extrusion parameters are a feeding zone of 160℃, a melting zone of 170-180℃, and a die of 195℃; The inner layer is a PE-RT layer, the extrusion parameters are a feeding zone of 180℃, a melting zone of 200-210℃, and a die of 165℃; The hot melt adhesive is mixed with the PP and the PE in a certain proportion, and is applied to the production of temperature-resistant and pressure-resistant composite pipe material with a multi-layer composite structure of outer PP-R and inner PE-RT plastic products.

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