Polypropylene hot melt adhesive as well as preparation method and application thereof

Abstract

The invention relates to a polypropylene hot melt adhesive as well as a preparation method and application thereof, and belongs to the technical field of hot melt adhesives. The polypropylene hot melt adhesive is prepared from the following components in parts by weight: 100 parts of maleic anhydride modified polypropylene resin, 10 to 20 parts of styrene-maleic anhydride copolymer resin, 20 to 40 parts of flame-retardant filler, 2 to 5 parts of curing agent and 150 to 200 parts of solvent, the molecular weight Mw of the maleic anhydride modified polypropylene resin is 50000-70000, the acid value is 15 mgKOH / g-25 mgKOH / g, the content of maleic anhydride is 1 wt%-2 wt%, and the melting point is 70 DEG C-100 DEG C. The invention further discloses a preparation method of the maleic anhydride modified polypropylene resin. According to the polypropylene hot melt adhesive disclosed by the invention, by compounding the styrene-maleic anhydride copolymer resin, maleic anhydride functional groups in the styrene-maleic anhydride copolymer resin can react with maleic anhydride in maleic anhydride modified polypropylene resin or form hydrogen bonds, so that the compatibility of the styrene-maleic anhydride copolymer resin and the maleic anhydride modified polypropylene resin is enhanced, and phase separation is reduced; and a more uniform composite material is formed. Meanwhile, the copolymer resin is used as an elastomer, so that the toughness of polypropylene can be improved to a certain extent, and the impact resistance of the material is improved.

Description

Technical Field

[0001] The invention belongs to the technical field of hot melt adhesives, and in particular relates to a polypropylene hot melt adhesive and a preparation method and application thereof. Background Art

[0002] As an adhesive widely used in various industries, hot melt adhesive has been widely welcomed due to its unique advantages such as non-toxicity and fast curing. With the development of the manufacturing industry, the demand for high-bonding strength hot melt adhesive has continued to increase. Especially in the fields of automobiles, electronics, construction, etc., high-bonding strength hot melt adhesive has been widely used due to its excellent bonding performance and durability. In summary, the application trend of high-bonding strength hot melt adhesive will be further expanded, and its market demand and technical level will continue to improve.

[0003] At present, most of the existing polypropylene hot melt adhesives on the market are maleic anhydride grafted polypropylene hot melt adhesives. The grafting rate of maleic anhydride grafted polypropylene is generally 0.5%-2.0%. The low grafting rate of maleic anhydride leads to poor bonding effect of polypropylene hot melt adhesive, low bonding strength, and easy bonding delamination. However, after increasing the grafting rate of maleic anhydride, the introduction of a large amount of maleic anhydride will accelerate the degradation of polypropylene at high temperature, especially in the melt processing process. High grafting rate may also lead to a decrease in the toughness of the material, especially in a low temperature environment, the impact resistance of the material is significantly weakened, and brittle fracture is prone to occur. For example, invention patent CN 103756595A discloses a modified polypropylene hot melt adhesive, which is prepared by blending maleic anhydride modified polypropylene with ethylene (propylene) copolymer, copolymerized polypropylene, elastomer and other resins. However, the melt index of maleic anhydride functionalized modified polypropylene is relatively high, indicating that it is easy to degrade and has a low molecular weight, which will lead to poor bonding strength of the hot melt adhesive and poor temperature and weather resistance. Invention patent CN 109796912A discloses a modified polypropylene hot melt adhesive, in which low-crystallinity ethylene-α-olefin copolymer is added in the process of preparing functionalized modified polypropylene. Although low-crystallinity ethylene-α-olefin copolymer can improve the toughness of polypropylene, in some cases, the compatibility between the elastomer and polypropylene is poor, which may cause the two phases to separate and form an uneven microstructure. This will not only affect the mechanical properties of the material, but may also cause appearance defects of the product, such as uneven surface or delamination, resulting in insufficient bonding and bonding failure.

[0004] In summary, the existing hot melt adhesive still has the problem of insufficient bonding strength, which will affect the use effect and product quality. Therefore, how to improve the bonding strength of hot melt adhesive is still a problem that needs to be solved urgently. Summary of the invention

[0005] In order to solve the above technical problems, the present invention provides a polypropylene hot melt adhesive and its preparation method and application. By adding styrene-maleic anhydride copolymer resin to the polypropylene hot melt adhesive, more carboxyl groups contained therein react with the surface of polar materials to form chemical bonds, which greatly improves the bonding strength of different interfaces, so that the polypropylene hot melt adhesive has excellent bonding strength and adaptability to a variety of materials. At the same time, due to the polarity and reactivity of maleic anhydride, the polypropylene hot melt adhesive is given better heat resistance and chemical stability; in addition, the polypropylene hot melt adhesive is added with flame retardant fillers with flame retardant effect, so that the polypropylene hot melt adhesive has excellent flame retardant function; the polypropylene hot melt adhesive is coated on the substrate layer to make a multifunctional hot melt adhesive film with high strength, high heat resistance, insulation and flame retardant properties.

[0006] The first object of the present invention is to provide a polypropylene hot melt adhesive, which comprises, by weight, 100 parts of maleic anhydride modified polypropylene resin, 10-20 parts of styrene-maleic anhydride copolymer resin, 20-40 parts of flame retardant filler, 2-5 parts of curing agent, and 150-200 parts of solvent; the molecular weight Mn of the styrene-maleic anhydride copolymer resin is 4000-10000, the acid value is 110mgKOH / g-220mgKOH / g, the maleic anhydride content is 5wt%-20wt%, and the glass transition temperature Tg is 100℃-120℃. Within this molecular weight range, the styrene-maleic anhydride copolymer resin generally has good solubility. The styrene-maleic anhydride copolymer resin has high acidity and can be easily dissolved in a variety of organic solvents, which makes them very suitable for the formulation of coatings, inks and adhesives. Due to the high acid value and maleic anhydride content, the styrene-maleic anhydride copolymer resin has more functional groups, such as carboxyl and anhydride groups, which can participate in various chemical reactions, such as cross-linking reactions with polyols, amines, epoxy resins, etc., thereby improving the performance of the material. The higher Tg indicates that the resin is more stable when heated and is not easy to soften or deform, which is very important for applications that require heat resistance, such as electronic packaging materials or coatings used in high temperature environments. The appropriate molecular weight and Tg help to provide better strength and toughness while maintaining a certain degree of flexibility. This is crucial for manufacturing durable products. This type of SMA resin can improve the wettability of hot melt adhesives to the objects being attached due to its moderate melt viscosity and good fluidity.

[0007] In one embodiment of the present invention, the styrene-maleic anhydride copolymer resin is composed of styrene and maleic anhydride in a molar ratio of (6-8):1. The styrene maleic anhydride copolymer is a thermoplastic resin synthesized by chemical reaction of styrene and maleic anhydride. By adjusting the ratio of the two monomers, the physical and chemical properties of the copolymer can be changed, thereby affecting its application performance; by selecting a styrene maleic anhydride copolymer with a high styrene content, the glass transition temperature (Tg) of the material is usually increased, which allows the material to maintain better dimensional stability and mechanical strength at higher temperatures; at the same time, copolymers with a higher styrene content may have better resistance to certain solvents and chemicals; increasing the styrene content can improve the fluidity of the material, enhance the wetting effect of the hot melt adhesive on the substrate and the object to be adhered, and improve the processing performance.

[0008] Furthermore, the molar ratio of styrene to maleic anhydride in the styrene-maleic anhydride copolymer resin is (6:1), (7:1), (8:1), etc.

[0009] In one embodiment of the present invention, the maleic anhydride modified polypropylene resin has a molecular weight Mw of 50000-70000, an acid value of 15mgKOH / g-25mgKOH / g, a maleic anhydride content of 1wt%-2wt%, and a melting point of 70°C-100°C. While ensuring that the material has excellent mechanical properties, thermal properties and processing properties, it can improve its compatibility and adhesion properties with other materials, and is suitable for a variety of application fields with high performance requirements.

[0010] Further, the weight portion of the maleic anhydride modified polypropylene resin may be 100 parts, etc.;

[0011] The weight parts of the styrene-maleic anhydride copolymer resin can be 10 parts, 11 parts, 12 parts, 13 parts, 14 parts, 15 parts, 16 parts, 17 parts, 18 parts, 19 parts, 20 parts, etc.;

[0012] The weight parts of the flame retardant filler can be 20 parts, 21 parts, 22 parts, 23 parts, 24 parts, 25 parts, 26 parts, 27 parts, 28 parts, 29 parts, 30 parts, 31 parts, 32 parts, 33 parts, 34 parts, 35 parts, 36 parts, 37 parts, 38 parts, 39 parts, 40 parts, etc.;

[0013] The weight parts of the curing agent can be 2 parts, 3 parts, 4 parts, 5 parts, etc.;

[0014] The weight parts of the solvent can be 150 parts, 155 parts, 160 parts, 165 parts, 170 parts, 175 parts, 180 parts, 185 parts, 190 parts, 195 parts, 200 parts, etc.

[0015] In one embodiment of the present invention, the flame retardant filler is selected from one or more of phosphorus-based flame retardants, nitrogen-based flame retardants and metal hydroxide-based flame retardants.

[0016] Further, the phosphorus-based flame retardant is selected from aluminum diethylphosphinate and / or triethyl phosphate;

[0017] The nitrogen-based flame retardant is selected from melamine and / or melamine phosphate;

[0018] The metal hydroxide flame retardant is selected from aluminum hydroxide and / or magnesium hydroxide.

[0019] In one embodiment of the present invention, the curing agent is selected from one or more of bisphenol A epoxy resin, bisphenol F epoxy resin and dicyclopentadiene phenol epoxy resin.

[0020] In one embodiment of the present invention, the solvent is selected from one or more of xylene, dichloromethane, cyclohexane, butanone and ethyl acetate.

[0021] The second object of the present invention is to provide a method for preparing the polypropylene hot melt adhesive, comprising the following steps: styrene-maleic anhydride copolymer resin, curing agent and solvent are evenly dispersed, then flame retardant filler is added and stirred evenly, and finally maleic anhydride modified polypropylene resin is added and mixed evenly to obtain the polypropylene hot melt adhesive.

[0022] Further, the speeds for uniform dispersion, uniform stirring and uniform mixing are independently 800r / min-1000r / min, for example, 800r / min, 810r / min, 820r / min, 830r / min, 840r / min, 850r / min, 860r / min, 870r / min, 880r / min, 890r / min, 900r / min, 910r / min, 920r / min, 930r / min, 940r / min, 950r / min, 960r / min, 970r / min, 980r / min, 990r / min, 1000r / min, etc.; the time for uniform dispersion is 10min-20min, for example, 10min, 11min, 12min, 13min n, 14min, 15min, 16min, 17min, 18min, 19min, 20min, etc.; the time for uniform stirring is 40min-60min, for example, it can be 40min, 41min, 42min, 43min, 44min, 45min, 46min, 47min, 48min, 49min, 50min, 51min, 52min, 53min, 54min, 55min, 56min, 57min, 58min, 59min, 60min, etc.; the time for uniform mixing is 20min-30min, for example, it can be 20min, 21min, 22min, 23min, 24min, 25min, 26min, 27min, 28min, 29min, 30min, etc.

[0023] The third object of the present invention is to provide a multifunctional hot melt adhesive film, which comprises a substrate layer and an adhesive layer disposed on the substrate layer; the adhesive layer is prepared from the polypropylene hot melt adhesive.

[0024] In one embodiment of the present invention, the substrate layer is selected from a polypropylene film layer, a polyethylene terephthalate film layer, a polyimide film layer, a polycarbonate film layer or a polyamide film layer.

[0025] In one embodiment of the present invention, the thickness of the substrate layer is 25 μm-125 μm; the thickness of the adhesive layer is 20 μm-50 μm.

[0026] Further, the thickness of the substrate layer is 25 μm, 30 μm, 35 μm, 40 μm, 45 μm, 50 μm, 55 μm, 60 μm, 65 μm, 70 μm, 75 μm, 80 μm, 85 μm, 90 μm, 95 μm, 100 μm, 105 μm, 110 μm, 115 μm, 120 μm, 125 μm; or any thickness value between any two values; the thickness of the adhesive layer is 20 μm, 21 μm, or any thickness value between any two values.

[0027] The technical solution of the present invention has the following advantages over the prior art:

[0028] (1) The polypropylene hot melt adhesive of the present invention is compounded by maleic anhydride modified polypropylene resin and styrene-maleic anhydride copolymer resin, so that the maleic anhydride functional group in the styrene-maleic anhydride copolymer resin can react with the maleic anhydride in the maleic anhydride modified polypropylene resin or form a hydrogen bond, thereby enhancing the compatibility of the two, reducing phase separation, and forming a more uniform composite material. At the same time, as an elastomer, the styrene-maleic anhydride copolymer resin can improve the toughness of polypropylene to a certain extent and reduce the risk of brittle fracture; especially in a low temperature environment, the styrene-maleic anhydride copolymer resin can help improve the impact resistance of the material.

[0029] (2) The multifunctional hot-melt adhesive film of the present invention has excellent bonding strength and temperature resistance, as well as excellent weather resistance. The multifunctional hot-melt adhesive film is hot-pressed and attached to the object to be adhered, and is suitable for bonding polar materials (such as metal, glass, rubber, ceramics, etc.). BRIEF DESCRIPTION OF THE DRAWINGS

[0030] In order to make the content of the present invention more clearly understood, the present invention is further described in detail below according to specific embodiments of the present invention in conjunction with the accompanying drawings, wherein:

[0031] Figure 1 It is a schematic structural diagram of the insulating adhesive film for busbar of the present invention;

[0032] Explanation of reference numerals: 1-substrate layer, 2-adhesive layer. DETAILED DESCRIPTION

[0033] The present invention is further described below in conjunction with the accompanying drawings and specific embodiments so that those skilled in the art can better understand the present invention and implement it. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. It should be understood that the specific embodiments are only used to explain the present invention, but the embodiments are not intended to limit the present invention.

[0034] In the present invention, unless otherwise explained, technical and scientific terms used in the present invention have the same meanings as commonly understood by those skilled in the art to which the present invention belongs.

[0035] In the present invention, unless otherwise stated, the term "and / or" used in the present invention includes any and all combinations of one or more of the associated listed items.

[0036] In the present invention, unless otherwise stated, the experimental methods used in the embodiments of the present invention are conventional methods unless otherwise stated, and the materials, reagents, etc. used are all commercially available unless otherwise stated.

[0037] In the present invention, unless otherwise stated, when the terms "comprise" and / or "include" are used in the specification of the present invention, it indicates the existence of the described features, integers, steps, operations, raw materials or components, but does not exclude the existence or addition of one or more other features, integers, steps, operations, raw materials, components or their combinations.

[0038] In the present invention, unless otherwise specified,

[0039] In the present invention, unless otherwise specified,

[0040] Example 1

[0041] Reference Figure 1 As shown, the busbar insulating adhesive film of this embodiment includes a substrate layer 1 and an adhesive layer 2 arranged on the substrate layer 1; wherein the substrate layer 1 is a polyimide film layer with a thickness of 50 μm; the adhesive layer 2 has a thickness of 30 μm; the adhesive layer 2 is loaded into a coating machine with polypropylene hot melt adhesive, and is coated on the substrate layer 1 with a thickness of 50 μm, and then baked to dry the surface;

[0042] The raw material components of the polypropylene hot melt adhesive and their weight parts are as follows: 100 parts of maleic anhydride modified polypropylene resin, 10 parts of styrene-maleic anhydride copolymer resin, 30 parts of flame retardant filler, 2 parts of curing agent, and 200 parts of solvent;

[0043] The maleic anhydride modified polypropylene resin was purchased from Toyobo, Japan, with the model number of PMA-KE, a melting point of 95°C, a molecular weight of 60,000, an acid value of 21 mgKOH / g, and a maleic anhydride content of 1.8 wt%;

[0044] Styrene-maleic anhydride copolymer resin was purchased from Polyscope of the Netherlands, model EF60, with a molar ratio of styrene to maleic anhydride of 6:1, a molecular weight Mn of 5500, an acid value of 155 mgKOH / g, a maleic anhydride content of 13 wt %, and a glass transition temperature Tg of 105° C.;

[0045] The flame retardant filler is a phosphorus-based flame retardant purchased from Clariant Chemicals, model number OP935;

[0046] The curing agent is bisphenol A epoxy resin purchased from Nan Ya Plastics Industry, model NPEL-134;

[0047] The solvent was toluene and ethyl acetate (volume ratio 1:1);

[0048] The preparation of polypropylene hot melt adhesive specifically includes the following steps: styrene-maleic anhydride copolymer resin, curing agent and solvent are mixed, and high-speed disperser is used to disperse for 15 minutes at a speed of 900r / min, and then flame retardant filler is slowly added. After the addition is completed, the dispersion is continued for 50 minutes, and finally maleic anhydride modified polypropylene resin is slowly added and dispersed for 25 minutes to obtain polypropylene hot melt adhesive.

[0049] Example 2

[0050] Reference Figure 1 As shown, the busbar insulating adhesive film of this embodiment includes a substrate layer 1 and an adhesive layer 2 arranged on the substrate layer 1; wherein the substrate layer 1 is a polyimide film layer with a thickness of 50 μm; the adhesive layer 2 has a thickness of 30 μm; the adhesive layer 2 is loaded into a coating machine with polypropylene hot melt adhesive, and is coated on the substrate layer 1 with a thickness of 50 μm, and then baked to dry the surface;

[0051] The raw material components of the polypropylene hot melt adhesive and their weight parts are as follows: 100 parts of maleic anhydride modified polypropylene resin, 15 parts of styrene-maleic anhydride copolymer resin, 30 parts of flame retardant filler, 2 parts of curing agent, and 200 parts of solvent;

[0052] The maleic anhydride modified polypropylene resin was purchased from Toyobo, Japan, with the model number of PMA-KE, a melting point of 95°C, a molecular weight of 60,000, an acid value of 21 mgKOH / g, and a maleic anhydride content of 1.8 wt%;

[0053] Styrene-maleic anhydride copolymer resin was purchased from Polyscope of the Netherlands, model EF60, with a molar ratio of styrene to maleic anhydride of 6:1, a molecular weight Mn of 5500, an acid value of 155 mgKOH / g, a maleic anhydride content of 13 wt %, and a glass transition temperature Tg of 105° C.;

[0054] The flame retardant filler is a phosphorus-based flame retardant purchased from Clariant Chemicals, model number OP935;

[0055] The curing agent is bisphenol A epoxy resin purchased from Nan Ya Plastics Industry, model NPEL-134;

[0056] The solvent was toluene and ethyl acetate (volume ratio 1:1);

[0057] The preparation of polypropylene hot melt adhesive specifically includes the following steps: styrene-maleic anhydride copolymer resin, curing agent and solvent are mixed, and high-speed disperser is used to disperse for 15 minutes at a speed of 900r / min, and then flame retardant filler is slowly added. After the addition is completed, the dispersion is continued for 50 minutes, and finally maleic anhydride modified polypropylene resin is slowly added and dispersed for 25 minutes to obtain polypropylene hot melt adhesive.

[0058] Example 3

[0059] Reference Figure 1 As shown, the busbar insulating adhesive film of this embodiment includes a substrate layer 1 and an adhesive layer 2 arranged on the substrate layer 1; wherein the substrate layer 1 is a polyimide film layer with a thickness of 50 μm; the adhesive layer 2 has a thickness of 30 μm; the adhesive layer 2 is loaded into a coating machine with polypropylene hot melt adhesive, and is coated on the substrate layer 1 with a thickness of 50 μm, and then baked to dry the surface;

[0060] The raw material components of the polypropylene hot melt adhesive and their weight parts are as follows: 100 parts of maleic anhydride modified polypropylene resin, 20 parts of styrene-maleic anhydride copolymer resin, 30 parts of flame retardant filler, 2 parts of curing agent, and 200 parts of solvent;

[0061] The maleic anhydride modified polypropylene resin was purchased from Toyobo, Japan, with the model number of PMA-KE, a melting point of 95°C, a molecular weight of 60,000, an acid value of 21 mgKOH / g, and a maleic anhydride content of 1.8 wt%;

[0062] Styrene-maleic anhydride copolymer resin was purchased from Polyscope of the Netherlands, model EF60, with a molar ratio of styrene to maleic anhydride of 6:1, a molecular weight Mn of 5500, an acid value of 155 mgKOH / g, a maleic anhydride content of 13 wt %, and a glass transition temperature Tg of 105° C.;

[0063] The flame retardant filler is a phosphorus-based flame retardant purchased from Clariant Chemicals, model number OP935;

[0064] The curing agent is bisphenol A epoxy resin purchased from Nan Ya Plastics Industry, model NPEL-134;

[0065] The solvent was toluene and ethyl acetate (volume ratio 1:1);

[0066] The preparation of polypropylene hot melt adhesive specifically includes the following steps: styrene-maleic anhydride copolymer resin, curing agent and solvent are mixed, and high-speed disperser is used to disperse for 15 minutes at a speed of 900r / min, and then flame retardant filler is slowly added. After the addition is completed, the dispersion is continued for 50 minutes, and finally maleic anhydride modified polypropylene resin is slowly added and dispersed for 25 minutes to obtain polypropylene hot melt adhesive.

[0067] Example 4

[0068] Reference Figure 1 As shown, the busbar insulating adhesive film of this embodiment includes a substrate layer 1 and an adhesive layer 2 arranged on the substrate layer 1; wherein the substrate layer 1 is a polyimide film layer with a thickness of 50 μm; the adhesive layer 2 has a thickness of 30 μm; the adhesive layer 2 is loaded into a coating machine with polypropylene hot melt adhesive, and is coated on the substrate layer 1 with a thickness of 50 μm, and then baked to dry the surface;

[0069] The raw material components of the polypropylene hot melt adhesive and their weight parts are as follows: 100 parts of maleic anhydride modified polypropylene resin, 10 parts of styrene-maleic anhydride copolymer resin, 30 parts of flame retardant filler, 5 parts of curing agent, and 200 parts of solvent;

[0070] The maleic anhydride modified polypropylene resin was purchased from Toyobo, Japan, with the model number of PMA-KE, a melting point of 95°C, a molecular weight of 60,000, an acid value of 21 mgKOH / g, and a maleic anhydride content of 1.8 wt%;

[0071] Styrene-maleic anhydride copolymer resin was purchased from Polyscope of the Netherlands, model EF60, with a molar ratio of styrene to maleic anhydride of 6:1, a molecular weight Mn of 5500, an acid value of 155 mgKOH / g, a maleic anhydride content of 13 wt %, and a glass transition temperature Tg of 105° C.;

[0072] The flame retardant filler is a phosphorus-based flame retardant purchased from Clariant Chemicals, model number OP935;

[0073] The curing agent is bisphenol A epoxy resin purchased from Nan Ya Plastics Industry, model NPEL-134;

[0074] The solvent was toluene and ethyl acetate (volume ratio 1:1);

[0075] The preparation of polypropylene hot melt adhesive specifically includes the following steps: styrene-maleic anhydride copolymer resin, curing agent and solvent are mixed, and high-speed disperser is used to disperse for 15 minutes at a speed of 900r / min, and then flame retardant filler is slowly added. After the addition is completed, the dispersion is continued for 50 minutes, and finally maleic anhydride modified polypropylene resin is slowly added and dispersed for 25 minutes to obtain polypropylene hot melt adhesive.

[0076] Example 5

[0077] Reference Figure 1 As shown, the busbar insulating adhesive film of this embodiment includes a substrate layer 1 and an adhesive layer 2 arranged on the substrate layer 1; wherein the substrate layer 1 is a polyimide film layer with a thickness of 50 μm; the adhesive layer 2 has a thickness of 30 μm; the adhesive layer 2 is loaded into a coating machine with polypropylene hot melt adhesive, and is coated on the substrate layer 1 with a thickness of 50 μm, and then baked to dry the surface;

[0078] The raw material components of the polypropylene hot melt adhesive and their weight parts are as follows: 100 parts of maleic anhydride modified polypropylene resin, 10 parts of styrene-maleic anhydride copolymer resin, 30 parts of flame retardant filler, 5 parts of curing agent, and 200 parts of solvent;

[0079] The maleic anhydride modified polypropylene resin was purchased from Toyobo, Japan, with the model number of PMA-KE, a melting point of 95°C, a molecular weight of 60,000, an acid value of 21 mgKOH / g, and a maleic anhydride content of 1.8 wt%;

[0080] Styrene-maleic anhydride copolymer resin was purchased from Polyscope of the Netherlands, model EF60, with a molar ratio of styrene to maleic anhydride of 6:1, a molecular weight Mn of 5500, an acid value of 155 mgKOH / g, a maleic anhydride content of 13 wt %, and a glass transition temperature Tg of 105° C.;

[0081] The flame retardant filler is a phosphorus-based flame retardant purchased from Clariant Chemicals, model number OP935;

[0082] The curing agent is bisphenol A epoxy resin purchased from Nan Ya Plastics Industry, model NPEL-134;

[0083] The solvent was toluene and ethyl acetate (volume ratio 1:1);

[0084] The preparation of polypropylene hot melt adhesive specifically includes the following steps: styrene-maleic anhydride copolymer resin, curing agent and solvent are mixed, and high-speed disperser is used to disperse for 15 minutes at a speed of 900r / min, and then flame retardant filler is slowly added. After the addition is completed, the dispersion is continued for 50 minutes, and finally maleic anhydride modified polypropylene resin is slowly added and dispersed for 25 minutes to obtain polypropylene hot melt adhesive.

[0085] Example 6

[0086] Reference Figure 1As shown, the busbar insulating adhesive film of this embodiment includes a substrate layer 1 and an adhesive layer 2 arranged on the substrate layer 1; wherein the substrate layer 1 is a polyimide film layer with a thickness of 50 μm; the adhesive layer 2 has a thickness of 30 μm; the adhesive layer 2 is loaded into a coating machine with polypropylene hot melt adhesive, and is coated on the substrate layer 1 with a thickness of 50 μm, and then baked to dry the surface;

[0087] The raw material components of the polypropylene hot melt adhesive and their weight parts are as follows: 100 parts of maleic anhydride modified polypropylene resin, 20 parts of styrene-maleic anhydride copolymer resin, 30 parts of flame retardant filler, 5 parts of curing agent, and 200 parts of solvent;

[0088] The maleic anhydride modified polypropylene resin was purchased from Toyobo, Japan, with the model number of PMA-KE, a melting point of 95°C, a molecular weight of 60,000, an acid value of 21 mgKOH / g, and a maleic anhydride content of 1.8 wt%;

[0089] Styrene-maleic anhydride copolymer resin was purchased from Polyscope of the Netherlands, model EF60, with a molar ratio of styrene to maleic anhydride of 6:1, a molecular weight Mn of 5500, an acid value of 155 mgKOH / g, a maleic anhydride content of 13 wt %, and a glass transition temperature Tg of 105° C.;

[0090] The flame retardant filler is a phosphorus-based flame retardant purchased from Clariant Chemicals, model number OP935;

[0091] The curing agent is bisphenol A epoxy resin purchased from Nan Ya Plastics Industry, model NPEL-134;

[0092] The solvent was toluene and ethyl acetate (volume ratio 1:1);

[0093] The preparation of polypropylene hot melt adhesive specifically includes the following steps: styrene-maleic anhydride copolymer resin, curing agent and solvent are mixed, and high-speed disperser is used to disperse for 15 minutes at a speed of 900r / min, and then flame retardant filler is slowly added. After the addition is completed, the dispersion is continued for 50 minutes, and finally maleic anhydride modified polypropylene resin is slowly added and dispersed for 25 minutes to obtain polypropylene hot melt adhesive.

[0094] Comparative Example 1

[0095] The method is basically the same as Example 1, except that no styrene-maleic anhydride copolymer resin is added.

[0096] Comparative Example 2

[0097] The method is basically the same as Example 1, except that the amount of styrene-maleic anhydride copolymer resin is replaced with 30 parts.

[0098] Comparative Example 3

[0099] The method is basically the same as Example 1, except that the styrene-maleic anhydride copolymer resin is replaced by a styrene-maleic anhydride copolymer resin EF10 purchased from Polyscope of the Netherlands, wherein the molar ratio of styrene to maleic anhydride in EF10 is 1:1, the molecular weight Mn is 5000, the acid value is 480 mgKOH / g, the maleic anhydride content is 42 wt %, and the glass transition temperature Tg is 155° C.

[0100] Comparative Example 4

[0101] The method is basically the same as Example 1, except that the styrene-maleic anhydride copolymer resin is replaced by a styrene-maleic anhydride copolymer resin EF30 purchased from Polyscope of the Netherlands, wherein the molar ratio of styrene to maleic anhydride in EF30 is 3:1, the molecular weight Mn is 9500, the acid value is 280 mgKOH / g, the maleic anhydride content is 23 wt %, and the glass transition temperature Tg is 125°C.

[0102] Comparative Example 5

[0103] The method is basically the same as Example 1, except that the amount of the flame retardant filler is replaced by 10 parts.

[0104] Performance Testing

[0105] The hot melt adhesive films of Examples 1-6 and Comparative Examples 1-5 were tested, and the test methods of each test item were as follows:

[0106] Peel strength (N / mm): Cut the hot melt adhesive film into 300mm wide and 150mm long, and press the cut hot melt adhesive film onto an aluminum plate at a temperature of 120-140°C, a time of 40s-180s, and a pressure of 0.7Mpa-2Mpa. Cool to room temperature for testing; peel direction 180°, rate 100mm / min;

[0107] Shear strength (Mpa): Cut the hot-pressed aluminum sheet into 25mm×100mm samples, use a blank aluminum sheet of the same size to apply high-strength structural adhesive with an overlap area of ​​25mm×12.5mm, bake at 80℃ for 8 hours to cure and cross-link the structural adhesive, cool to room temperature after complete curing and place for 24 hours before testing; stretch direction 180°, stretch rate 4mm / min, shear strength = maximum test force / actual bonding area;

[0108] Flame retardant performance: tested according to UL94V-0 flame retardant test standard;

[0109] High temperature and high humidity aging test: same as sample preparation method 1 and 2, put the sample into high temperature and high humidity environment box for 1000 hours, test conditions are: 85℃ / 85%RH / 1000 hours; take out and cool to room temperature, test peel strength and shear strength;

[0110] Thermal shock aging test: same as sample preparation method 1 and 2, put the sample into thermal shock environment box for 1000 hours, test conditions are: -40℃ constant temperature for 0.5 hours, 85℃ constant temperature for 0.5 hours, hot and cold switching time within 2 minutes, after 1000 cycles, take out and cool to room temperature, test peel strength and shear strength;

[0111] High temperature aging test: same as sample preparation method 1 and 2, put the sample into a 125℃ high temperature oven for 1000 hours, take it out and cool it to room temperature after aging for 1000 hours, and test the peel strength and shear strength.

[0112] Table 1

[0113]

[0114]

[0115] As can be seen from Table 1, the multifunctional hot melt adhesive film prepared from the polypropylene hot melt adhesive of Examples 1-6 has a peel strength of 2.1N / mm-2.3N / mm, a shear strength of 12Mpa-15Mpa, a flame retardant grade of V-0, and excellent high temperature and high humidity, cold and hot shock and high temperature aging properties.

[0116] Compared with Example 1, in Comparative Example 1, no styrene and maleic anhydride copolymer was added, and the bonding performance of the hot melt adhesive was extremely poor and unsatisfactory for use.

[0117] Compared with Example 1, the amount of styrene and maleic anhydride copolymer EF60 used in Comparative Example 2 is 30 parts, which is a relatively large amount. Although the bonding performance is excellent, excessive addition introduces too many maleic anhydride groups, resulting in a decrease in the high temperature and high humidity resistance of the hot melt adhesive.

[0118] Compared with Example 1, the molar ratio of styrene to maleic anhydride in the styrene and maleic anhydride copolymer EF10 used in Comparative Example 3 is 1:1, the maleic anhydride content in the resin is relatively high, and the molecular weight is relatively small. After addition, the high temperature and high humidity resistance and high temperature performance of the hot melt adhesive are reduced.

[0119] Compared with Example 1, the molar ratio of styrene to maleic anhydride in the styrene and maleic anhydride copolymer EF10 used in Comparative Example 4 is 3:1, and the molecular weight is also not high, and the resin acid value is relatively high, which easily leads to a decrease in the high temperature and high humidity resistance and high temperature performance of the hot melt adhesive. The hot melt adhesive is easily debonded from the substrate and cannot meet the requirements of use.

[0120] Compared with Example 1, the amount of flame retardant OP935 used in Comparative Example 5 is 10 parts, and the flame retardant filler is less. During the combustion test, the hot melt adhesive is prone to dripping and igniting the absorbent cotton, and the hot melt adhesive film has a poor flame retardant effect.

[0121] Obviously, the above embodiments are merely examples for clear explanation and are not intended to limit the implementation methods. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation methods here. The obvious changes or modifications derived from these are still within the protection scope of the invention.

Claims

1. A polypropylene hot melt adhesive, characterized in that: The polypropylene hot melt adhesive comprises, by weight, 100 parts of maleic anhydride modified polypropylene resin, 10-20 parts of styrene-maleic anhydride copolymer resin, 20-40 parts of flame retardant filler, 2-5 parts of curing agent, and 150-200 parts of solvent; the molecular weight Mn of the styrene-maleic anhydride copolymer resin is 4000-10000, the acid value is 110mgKOH / g-220mgKOH / g, the maleic anhydride content is 5wt%-20wt%, and the glass transition temperature Tg is 100°C-120°C.

2. The polypropylene hot melt adhesive according to claim 1, characterized in that: The styrene-maleic anhydride copolymer resin is composed of styrene and maleic anhydride in a molar ratio of (6-8):

1.

3. The polypropylene hot melt adhesive according to claim 1, characterized in that: The maleic anhydride modified polypropylene resin has a molecular weight Mw of 50000-70000, an acid value of 15 mgKOH / g-25 mgKOH / g, a maleic anhydride content of 1 wt%-2 wt%, and a melting point of 70°C-100°C.

4. The polypropylene hot melt adhesive according to claim 1, characterized in that: The flame retardant filler is selected from one or more of phosphorus flame retardants, nitrogen flame retardants, silicon flame retardants, metal hydroxide flame retardants, metal oxide flame retardants and metal boride flame retardants.

5. The polypropylene hot melt adhesive according to claim 1, characterized in that: The curing agent is selected from one or more of bisphenol A epoxy resin, bisphenol F epoxy resin and dicyclopentadiene phenol epoxy resin.

6. The polypropylene hot melt adhesive according to claim 1, characterized in that: The solvent is selected from one or more of xylene, dichloromethane, cyclohexane, butanone and ethyl acetate.

7. The method for preparing the polypropylene hot melt adhesive according to any one of claims 1 to 6, characterized in that: The following steps are involved: The styrene-maleic anhydride copolymer resin, curing agent and solvent are evenly dispersed, then the flame retardant filler is added and stirred evenly, and finally the maleic anhydride modified polypropylene resin is added and mixed evenly to obtain the polypropylene hot melt adhesive.

8. A multifunctional hot melt adhesive film, characterized in that: The multifunctional hot melt adhesive film comprises a substrate layer and an adhesive layer disposed on the substrate layer; the adhesive layer is prepared from the polypropylene hot melt adhesive according to any one of claims 1 to 6.

9. The multifunctional hot melt adhesive film according to claim 8, characterized in that: The substrate layer is selected from a polypropylene film layer, a polyethylene terephthalate film layer, a polyimide film layer, a polycarbonate film layer or a polyamide film layer.

10. The multifunctional hot melt adhesive film according to claim 8, characterized in that: The thickness of the substrate layer is 25 μm-125 μm; the thickness of the adhesive layer is 20 μm-50 μm.

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