A polyester hot melt adhesive and its preparation method and application

Abstract

The present invention provides a polyester hot melt adhesive and a preparation method and application thereof. The polyester hot melt adhesive comprises 50-60 parts of a first polyester resin, 10-20 parts of a second polyester resin and 20-30 parts of a third polyester resin in parts by weight; the raw materials for preparing the first polyester resin include aromatic dibasic acid, diol and polyamine; the raw materials for preparing the second polyester resin include aliphatic dibasic acid and aliphatic long-chain diol; the raw materials for preparing the third polyester resin include dibasic acid, diol and polypropylene grafted maleic anhydride. In the present invention, the polyester hot melt adhesive is compounded by three polyester resins with specific structures, so that the polyester hot melt adhesive has both excellent high temperature resistance and low temperature resistance, can be used for a long time under high and low temperature conditions, will not have debonding, film shrinkage, edge warping and other phenomena, has good high and low temperature cycle resistance, and has low construction viscosity, good adhesion to a variety of substrates, high adhesion, and a wide range of applications.

Description

Technical Field

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

[0002] Adhesives are used as connecting materials for bonding different materials in many scenarios, including home decoration, automobiles and other fields. Hot melt adhesives have always been popular as solvent-free adhesives, but the hot melt adhesives in the existing technology need to be further improved in terms of construction performance and product performance.

[0003] At present, most of the commonly used hot melt adhesives are mainly polyolefins, ethylene-vinyl acetate copolymers (EVA), block copolymers (such as SBS), etc. However, polyolefin hot melt adhesives have poor high temperature resistance and are easy to soften and debond at high temperatures; EVA and SBS series have high melt viscosity, poor construction performance, and high brittleness at low temperatures.

[0004] CN113881369A discloses a high-temperature resistant hot melt adhesive, the application field of which is concentrated in the field of automobile filters. The main technical means is to use EVA as the base resin and introduce tackifying resin, viscosity regulator and nano-silicon dioxide to improve its high-temperature resistance. However, the hot melt adhesive has poor low-temperature resistance, and the viscosity increases after the introduction of silicon dioxide, the construction performance deteriorates, and the application range is narrow. In addition, the method of introducing metal oxides cannot fundamentally improve the overall heat resistance.

[0005] For example, CN101307214A discloses a hot melt adhesive and a preparation method thereof. The hot melt adhesive is made of an elastomer, a synthetic high melting point wax, a synthetic resin, a plasticizer and an antioxidant, and can have a certain high temperature resistance. The introduction of a plasticizer can reduce the melt viscosity, but it leads to high low temperature brittleness of the material and poor high and low temperature cycle performance.

[0006] CN114752319A discloses a high initial viscosity, high temperature resistant hot melt adhesive and a preparation method thereof, which is based on polyolefin and is designed by combining high and low viscosity polyolefins and auxiliary tackifying resins and other components, and has a certain improvement in high temperature resistance; however, its low temperature resistance and high and low temperature cycle resistance are poor.

[0007] Therefore, developing a polyester hot melt adhesive that has excellent high and low temperature resistance, can be used for a long time in high and low temperature environments, will not experience debonding, film shrinkage, warping, etc., has good high and low temperature cycle resistance, low construction viscosity, good adhesion to a variety of substrates, and high adhesion is a technical problem that needs to be urgently solved in this field. Summary of the invention

[0008] In view of the deficiencies in the prior art, the purpose of the present invention is to provide a polyester hot melt adhesive and a preparation method and application thereof. The polyester hot melt adhesive is compounded by three polyester resins with specific structures, so that the polyester hot melt adhesive has both excellent high temperature resistance and low temperature resistance, high heat resistance temperature, and still has excellent mechanical properties at lower temperatures. It can be used for a long time in high and low temperature environments without debonding, film shrinkage, edge warping, etc., and has good high and low temperature cycle resistance, low construction viscosity, good fit to a variety of substrates (such as polypropylene substrates, polystyrene substrates, etc.), high adhesion, and a wide range of applications.

[0009] To achieve this object, the present invention adopts the following technical solutions:

[0010] In a first aspect, the present invention provides a polyester hot melt adhesive, which comprises, by weight, 50 to 60 parts of a first polyester resin, 10 to 20 parts of a second polyester resin and 20 to 30 parts of a third polyester resin; the raw materials for preparing the first polyester resin comprise aromatic dibasic acids, diols and polyamines; the raw materials for preparing the second polyester resin comprise aliphatic dibasic acids and aliphatic long-chain diols; the raw materials for preparing the third polyester resin comprise dibasic acids, diols and polypropylene grafted maleic anhydride.

[0011] In the present invention, the raw materials for preparing the first polyester resin are selected from aromatic dibasic acids and diamines, and aromatic structures and amide structures are introduced to improve the high temperature resistance of polyester; the raw materials for preparing the second polyester resin are selected from aliphatic long-chain diols, and long-chain segment structures are introduced to enhance the flexibility of the polyester resin itself. In a low temperature environment, the resin has better ductility, and the long-chain segment structure can ensure that the hot melt adhesive has better low-temperature flexibility, and will not have debonding, film shrinkage, warping and other phenomena. When subjected to external forces, the external forces can be well offset internally, and the stress is digested internally, thereby achieving low-temperature characteristics; the raw materials for preparing the third polyester resin can make the polyester resin have good adhesion to various substrates such as polypropylene and polystyrene, and high adhesion; by compounding three polyester resins with specific structures at specific contents, the hot melt adhesive has better comprehensive performance and good resistance to cold and hot shocks.

[0012] In parts by weight, the polyester hot melt adhesive includes 50 to 60 parts of the first polyester resin, for example, 51 parts, 52 parts, 53 parts, 54 parts, 55 parts, 56 parts, 57 parts, 58 parts, 59 parts, etc.

[0013] In parts by weight, the polyester hot melt adhesive includes 10 to 20 parts of the second polyester resin, for example, 11 parts, 12 parts, 13 parts, 14 parts, 15 parts, 16 parts, 17 parts, 18 parts, 19 parts, etc.

[0014] In parts by weight, the polyester hot melt adhesive includes 20 to 30 parts of the third polyester resin, for example, 21 parts, 22 parts, 23 parts, 24 parts, 25 parts, 26 parts, 27 parts, 28 parts, 29 parts, etc.

[0015] In the present invention, the first polyester resin, the second polyester resin and the third polyester resin are compounded in specific contents so that the hot melt adhesive has excellent high temperature resistance, low temperature resistance and high adhesion to polypropylene and polystyrene substrates; if any component is not within the scope specified in this application, the performance of the hot melt adhesive will deteriorate.

[0016] Preferably, in the raw materials for preparing the first polyester resin, the mass ratio of aromatic dibasic acid, diol and polyamine is 1:(0.7-1.2):(0.2-0.5). The specific value of (0.7-1.2) can be, for example, 0.72, 0.74, 0.76, 0.78, 0.8, 0.82, 0.84, 0.86, 0.88, 0.9, 0.92, 0.94, 0.96, 0.98, 1, 1.05, 1.1, 1.15, etc.; the specific value of (0.2-0.5) can be, for example, 0.22, 0.24, 0.26, 0.28, 0.3, 0.32, 0.34, 0.36, 0.38, 0.4, 0.42, 0.44, 0.46, 0.48, etc.

[0017] In the present invention, if the proportion of polyamine in the raw materials for preparing the first polyester resin is too high, the hot melt adhesive will be too brittle as a whole and the mechanical properties will deteriorate; if the proportion is too small, the heat resistance of the hot melt adhesive will deteriorate.

[0018] Preferably, in the raw materials for preparing the first polyester resin, the aromatic dibasic acid includes at least one of terephthalic acid, phthalic acid or isophthalic acid.

[0019] Preferably, in the raw materials for preparing the first polyester resin, the aromatic dibasic acid includes at least terephthalic acid and phthalic acid; the mass ratio of terephthalic acid to phthalic acid is (1.2-1.7):1, for example, it can be 1.25:1, 1.3:1, 1.35:1, 1.4:1, 1.45:1, 1.5:1, 1.55:1, 1.6:1, 1.65:1, etc.

[0020] Preferably, in the raw materials for preparing the first polyester resin, the diol includes at least one of 1,6-hexanediol, 1,4-butanediol or octanediol.

[0021] Preferably, in the raw materials for preparing the first polyester resin, the mass ratio of 1,6-hexanediol, 1,4-butanediol and octanediol is (2-3):(1-2):1, wherein the specific values ​​in (2-3) can be, for example, 2.2, 2.4, 2.6, 2.8, etc.; the specific values ​​in (1-2) can be, for example, 1.2, 1.4, 1.6, 1.8, etc.

[0022] Preferably, the polyamine comprises aromatic polyamine and / or aliphatic polyamine.

[0023] Preferably, the polyamine includes at least one of phenylenediamine, dimethylpentanediamine, ethylenediamine or meta-xylylenediamine.

[0024] Preferably, in the polyamine, the mass ratio of the aromatic polyamine to the aliphatic polyamine is (0.5-1.5):1, for example, it can be 0.6:1, 0.7:1, 0.8:1, 0.9:1, 1:1, 1.1:1, 1.2:1, 1.3:1, 1.4:1, etc.

[0025] Preferably, the first polyester resin is prepared by the following method, which comprises:

[0026] In the presence of a catalyst, an aromatic dibasic acid, a diol and a polyamine are mixed, and the first polyester resin is obtained through a first reaction and a second reaction.

[0027] Preferably, the temperature of the first reaction is 170-190° C., for example, 175° C., 180° C., 185° C., etc.; the time is 1-3 h, for example, 1.5 h, 2 h, 2.5 h, etc.

[0028] Preferably, the temperature of the second reaction is 240-260° C., for example, 245° C., 250° C., 255° C., etc.; the time is 1-3 h, for example, 1.5 h, 2 h, 2.5 h, etc.

[0029] In the present invention, the first polyester resin introduces an amide structure into the polyester molecular chain by mixing and reacting an aromatic dibasic acid, a diol and a polyamine, so that the amide structure in the molecular chain is more evenly distributed. Compared with the polyester amide hot melt adhesive in which polyamide and polyester exist in segments, the high and low temperature resistance is better.

[0030] Preferably, the glass transition temperature of the first polyester resin is 120-140°C, for example, 122°C, 125°C, 128°C, 130°C, 132°C, 135°C, 138°C, etc.

[0031] Preferably, in the raw material for preparing the second polyester resin, the carbon number of the aliphatic long-chain diol is 6 to 12, for example, 7, 8, 9, 10, 11, etc.

[0032] In the present invention, when the number of carbon atoms in the aliphatic long-chain diol is within a specific range, the hot melt adhesive has better performance; when the number of carbon atoms is less than 6, the hot melt adhesive has poor low temperature resistance; when the number of carbon atoms is greater than 12, the polyester segment is too soft and the overall heat resistance deteriorates.

[0033] Preferably, in the raw materials for preparing the second polyester resin, the aliphatic long-chain diol includes at least one of heptanediol, octanediol, nonanediol or decanediol.

[0034] Preferably, in the raw material for preparing the second polyester resin, the number of carbon atoms of the aliphatic dibasic acid is 4 to 12, for example, 5, 6, 7, 8, 9, 10, 11, etc.

[0035] Preferably, in the raw materials for preparing the second polyester resin, the aliphatic dibasic acid includes at least one of succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid or sebacic acid.

[0036] Preferably, in the raw materials for preparing the second polyester resin, the aliphatic dibasic acid includes a combination of succinic acid and sebacic acid; the mass ratio of succinic acid to sebacic acid is (2-4):(6-8), for example, 2:8, 3:7, 4:6, etc.

[0037] Preferably, the glass transition temperature of the second polyester resin is 20-30°C, for example, 22°C, 24°C, 26°C, 28°C, etc.

[0038] In the present invention, the second polyester resin is prepared by the following method, which includes: in the presence of a catalyst, reacting an aliphatic dibasic acid and an aliphatic long-chain diol at 180-200° C. for 1-3 hours, and then continuing the polycondensation reaction at 240-260° C. for 1-3 hours to obtain the second polyester resin.

[0039] Preferably, in the raw materials for preparing the third polyester resin, the mass ratio of the dibasic acid, the diol and the polypropylene grafted maleic anhydride is (0.5-0.7):1:(0.15-0.45), wherein the specific value of (0.5-0.7) can be, for example, 0.51, 0.52, 0.53, 0.54, 0.55, 0.56, 0.57, 0.58, 0.59, 0.6, 0. 61, 0.62, 0.63, 0.64, 0.65, 0.66, 0.67, 0.68, 0.69, etc.; the specific values ​​in (0.15-0.45) can be, for example, 0.16, 0.18, 0.2, 0.22, 0.24, 0.26, 0.28, 0.3, 0.32, 0.34, 0.36, 0.38, 0.4, 0.42, 0.44, etc.

[0040] In the present invention, if the proportion of polypropylene grafted maleic anhydride in the raw materials for preparing the third polyester resin is too high, it will lead to difficulty in discharging and poor processability; if the proportion is too low, the adhesion to the substrate will be low.

[0041] Preferably, in the raw materials for preparing the third polyester resin, the dibasic acid includes at least one of an aromatic dibasic acid, an aliphatic dibasic acid or an alicyclic dibasic acid.

[0042] Preferably, in the raw materials for preparing the third polyester resin, the dibasic acid includes terephthalic acid and / or succinic acid.

[0043] Preferably, in the raw materials for preparing the third polyester resin, the diol includes an aliphatic diol.

[0044] Preferably, in the raw materials for preparing the third polyester resin, the diol includes 1-4-butanediol and / or pentanediol.

[0045] Preferably, the glass transition temperature of the third polyester resin is 60-80°C, for example, 62°C, 64°C, 66°C, 68°C, 70°C, 72°C, 74°C, 76°C, 78°C, etc.

[0046] In the present invention, the third polyester resin is prepared by the following method, which includes: in the presence of a catalyst, reacting a dibasic acid, a diol and polypropylene grafted with maleic anhydride at 180-200° C. for 1-3 hours, and then continuing the polycondensation reaction at 240-260° C. for 1-3 hours to obtain the third polyester resin.

[0047] In the present invention, when preparing the first polyester resin, the second polyester resin and the third polyester resin, the catalysts independently include at least one of cobalt acetate, tetrabutyl titanate, antimony trioxide, manganese acetate or germanium trioxide.

[0048] Preferably, the polyester hot melt adhesive further comprises at least one of a tackifying resin, a silane coupling agent, a viscosity regulator or an antioxidant.

[0049] Preferably, in parts by weight, the polyester hot melt adhesive includes 20 to 30 parts of a tackifying resin (for example, 22 parts, 24 parts, 26 parts, 28 parts, etc.), 2 to 4 parts of a silane coupling agent (for example, 2.2 parts, 2.4 parts, 2.6 parts, 2.8 parts, 3 parts, 3.2 parts, 3.4 parts, 3.6 parts, 3.8 parts, etc.), 10 to 20 parts of a viscosity regulator (for example, 12 parts, 14 parts, 16 parts, 18 parts, etc.) and 1 to 2 parts of an antioxidant (for example, 1.2 parts, 1.4 parts, 1.6 parts, 1.8 parts, etc.).

[0050] Preferably, the tackifying resin includes at least one of rosin resin, C5 petroleum resin, C9 petroleum resin or terpene resin.

[0051] Preferably, the tackifying resin includes at least one of a combination of C5 petroleum resin and terpene resin, a combination of C9 petroleum resin and terpene resin, or a combination of rosin resin and terpene resin.

[0052] Preferably, the viscosity modifier comprises polyethylene wax.

[0053] In a second aspect, the present invention provides a method for preparing the polyester hot melt adhesive according to the first aspect, the preparation method comprising:

[0054] The first polyester resin, the second polyester resin and the third polyester resin are mixed and extruded to obtain the polyester hot melt adhesive.

[0055] Preferably, the mixed material further comprises at least one of a tackifying resin, a silane coupling agent, a viscosity modifier or an antioxidant.

[0056] Preferably, the mixing is performed in a vibrating screen.

[0057] Preferably, the extrusion is carried out in a twin-screw extruder.

[0058] Preferably, the temperature of the first section of the twin-screw extruder is 140-160°C, for example, 145°C, 150°C, 155°C, etc.; the temperature of the second section is 190-210°C, for example, 195°C, 200°C, 205°C, etc.; the temperature of the third section is 250-270°C, for example, 255°C, 260°C, 265°C, etc.; the temperature of the fourth section is 240-260°C, for example, 245°C, 250°C, 255°C, etc.

[0059] In a third aspect, the present invention provides a polypropylene sheet, wherein the polypropylene sheet comprises the polyester hot melt adhesive as described in the first aspect.

[0060] The numerical range described in the present invention not only includes the point values ​​listed above, but also includes any point values ​​between the above numerical ranges that are not listed. Due to space limitations and for the sake of simplicity, the present invention no longer exhaustively lists the specific point values ​​included in the range.

[0061] Compared with the prior art, the present invention has the following beneficial effects:

[0062] The polyester hot melt adhesive provided by the present invention is compounded with three polyester resins with specific structures, so that the polyester hot melt adhesive has both excellent high temperature resistance and low temperature resistance, and has a high heat resistance temperature of more than 120°C. It still has excellent mechanical properties at lower temperatures, and can be used for a long time at low temperatures of -50°C and 120°C without debonding, film shrinkage, edge warping and the like. It has good high and low temperature cycle resistance, low construction viscosity, good fit for various substrates such as polypropylene and polystyrene, high adhesion, and a wide range of applications. DETAILED DESCRIPTION

[0063] The technical solution of the present invention is further described below by specific implementation methods. It should be understood by those skilled in the art that the embodiments are only to help understand the present invention and should not be regarded as specific limitations of the present invention.

[0064] The materials used in the present invention are as follows:

[0065] Polypropylene grafted with maleic anhydride: QF551 from Mitsui Chemicals, Japan.

[0066] Polyethylene grafted with maleic anhydride: American DuPont BYNEL41E871.

[0067] Silane coupling agent: γ-glycidyloxypropylsilane, brand KH560.

[0068] Viscosity regulator: PE wax, melting point 100-120°C, softening point 110°C.

[0069] Antioxidant: Antioxidant 1010, purchased from BYK.

[0070] Example 1

[0071] The present embodiment provides a polyester hot melt adhesive, which includes, by weight, 60 parts of a first polyester resin, 15 parts of a second polyester resin, 25 parts of a third polyester resin, 10 parts of a tackifying resin C5 petroleum resin, 15 parts of a tackifying resin terpene resin, 3 parts of a silane coupling agent KH560, 12 parts of PE wax, and 2 parts of an antioxidant 1010.

[0072] The raw materials for preparing the first polyester resin include aromatic dibasic acid, diol and polyamine in a mass ratio of 1:0.9:0.34; the aromatic dibasic acid includes terephthalic acid and phthalic acid in a mass ratio of 6:4; the diol includes 1,6-hexanediol, 1,4-butanediol and octanediol in a mass ratio of 5:3:2; the polyamine includes phenylenediamine and ethylenediamine in a mass ratio of 6:4; the glass transition temperature Tg of the first polyester resin is 125°C.

[0073] The raw materials for preparing the second polyester resin include aliphatic dibasic acid and octanediol in a mass ratio of 1:1.19; the aliphatic dibasic acid includes azelaic acid and succinic acid in a mass ratio of 7:3; and the Tg of the second polyester resin is 25°C.

[0074] The raw materials for preparing the third polyester resin include dibasic acid, diol and polypropylene grafted maleic anhydride in a mass ratio of 0.55:1:0.27; the dibasic acid includes terephthalic acid and succinic acid in a mass ratio of 6:4; the diol includes 1,4-butanediol and pentanediol in a mass ratio of 5.5:4.5; the Tg of the third polyester resin is 60°C.

[0075] This embodiment provides a method for preparing the polyester hot melt adhesive, comprising the following steps:

[0076] According to the formula, the first polyester resin, the second polyester resin, the third polyester resin, the tackifying resin C5 petroleum resin, the tackifying resin terpene resin, the silane coupling agent KH560, the PE wax and the antioxidant are preliminarily mixed in a vibrating screen, and then put into a twin-screw extruder for blending, and the first section temperature of the twin-screw extruder is 150° C., the second section temperature is 200° C., the third section temperature is 260° C., and the fourth section temperature is 250° C., and then granulated to obtain the polyester hot melt adhesive;

[0077] The preparation method of the first polyester resin comprises: heating aromatic dibasic acid, diol, polyamine and catalyst tetrabutyl titanate (accounting for 0.5% of the total mass of the system) to 180° C. in a system for esterification reaction for 2 hours, further heating to 250° C., vacuuming and reducing pressure for co-condensation for 2.5 hours to obtain the first polyester resin;

[0078] The preparation method of the second polyester resin comprises: heating aliphatic dibasic acid, octanediol and manganese acetate (accounting for 0.2% of the total mass of the system) to 190° C. in a system for esterification reaction for 2 hours, further heating to 250° C., vacuuming and reducing pressure for co-condensation for 2.5 hours to obtain the second polyester resin;

[0079] The preparation method of the third polyester resin comprises: heating the dibasic acid, diol and polypropylene grafted maleic anhydride and antimony trioxide (accounting for 0.3% of the total mass of the system) to 185° C. in the system for esterification reaction for 2 hours, continuing to heat to 250° C., and evacuating the system under reduced pressure for co-condensation for 2.5 hours to obtain the third polyester resin.

[0080] Example 2

[0081] The present embodiment provides a polyester hot melt adhesive, which includes, by weight, 55 parts of a first polyester resin, 20 parts of a second polyester resin, 30 parts of a third polyester resin, 10 parts of a tackifying resin C9 petroleum resin, 15 parts of a tackifying resin terpene resin, 2 parts of a silane coupling agent KH560, 15 parts of PE wax, and 2 parts of an antioxidant 1010.

[0082] The raw materials for preparing the first polyester resin include aromatic dibasic acid, diol and polyamine in a mass ratio of 1:0.79:0.45; the aromatic dibasic acid includes terephthalic acid, phthalic acid and isophthalic acid in a mass ratio of 5:4:1; the diol includes 1,6-hexanediol, 1,4-butanediol and octanediol in a mass ratio of 5:3:2; the polyamine includes phenylenediamine, ethylenediamine and meta-phenylenediamine in a mass ratio of 5:4:1; the glass transition temperature Tg of the first polyester resin is 135°C.

[0083] The raw materials for preparing the second polyester resin include aliphatic dibasic acid and octanediol in a mass ratio of 1:1.19; the aliphatic dibasic acid includes azelaic acid and succinic acid in a mass ratio of 8:2; and the Tg of the second polyester resin is 20°C.

[0084] The raw materials for preparing the third polyester resin include dibasic acid, diol and polypropylene grafted maleic anhydride in a mass ratio of 0.64:1:0.18; the dibasic acid includes terephthalic acid and succinic acid in a mass ratio of 7:3; the diol includes 1,4-butanediol and pentanediol in a mass ratio of 5.5:4.5; the Tg of the third polyester resin is 65°C.

[0085] This embodiment provides a method for preparing the polyester hot melt adhesive, and the specific steps are the same as those in Embodiment 1.

[0086] Example 3

[0087] The present embodiment provides a polyester hot melt adhesive, which includes, by weight, 50 parts of a first polyester resin, 20 parts of a second polyester resin, 25 parts of a third polyester resin, 10 parts of a tackifying resin rosin resin, 15 parts of a tackifying resin terpene resin, 2 parts of a silane coupling agent KH560, 10 parts of PE wax, and 2 parts of an antioxidant 1010.

[0088] The raw materials for preparing the first polyester resin include aromatic dibasic acid, diol and polyamine in a mass ratio of 1:1.01:0.22; the aromatic dibasic acid includes terephthalic acid, phthalic acid and isophthalic acid in a mass ratio of 5:3:2; the diol includes 1,6-hexanediol, 1,4-butanediol and octanediol in a mass ratio of 5:3:2; the polyamine includes phenylenediamine, ethylenediamine and dimethylpentanediamine in a mass ratio of 4:4:2; the glass transition temperature Tg of the first polyester resin is 122°C.

[0089] The raw materials for preparing the second polyester resin include aliphatic dibasic acid and octanediol in a mass ratio of 1:1.19; the aliphatic dibasic acid includes azelaic acid and succinic acid in a mass ratio of 6:4; and the Tg of the second polyester resin is 30°C.

[0090] The raw materials for preparing the third polyester resin include dibasic acid, diol and polypropylene grafted maleic anhydride in a mass ratio of 0.46:1:0.37; the dibasic acid includes terephthalic acid and succinic acid in a mass ratio of 7:3; the diol includes 1,4-butanediol and pentanediol in a mass ratio of 5.5:4.5; the Tg of the third polyester resin is 78°C.

[0091] This embodiment provides a method for preparing the polyester hot melt adhesive, and the specific steps are the same as those in Embodiment 1.

[0092] Example 4

[0093] This embodiment provides a polyester hot melt adhesive, which differs from Embodiment 1 only in that, in the raw materials for preparing the first polyester resin, the amount of polyamine is increased and the amount of polyol is reduced, so that the mass ratio of the aromatic dibasic acid, the diol and the polyamine is 1:0.69:0.55, and other raw material types, dosage ratios and preparation methods are the same as those in Embodiment 1.

[0094] Example 5

[0095] The present embodiment provides a polyester hot melt adhesive, which differs from the first embodiment only in that, in the raw materials for preparing the first polyester resin, the amount of polyamine is reduced and the amount of polyol is increased, so that the mass ratio of the aromatic dibasic acid, the diol and the polyamine is 1:1.14:0.1, and other raw material types, dosage ratios and preparation methods are the same as those in the first embodiment.

[0096] Example 6

[0097] The present embodiment provides a polyester hot melt adhesive, which differs from the first embodiment only in that, in the method for preparing the first polyester resin, an aromatic dibasic acid is first reacted with a diamine to obtain a polyamide prepolymer, and then a diol is added to the system for reaction to finally obtain the first polyester resin. Other raw material types, dosage ratios and process parameters are the same as those in the first embodiment.

[0098] Example 7

[0099] This embodiment provides a polyester hot melt adhesive, which differs from Embodiment 1 only in that, in the raw materials for preparing the second polyester resin, octanediol is replaced by pentadecanediol with an equal molar amount of hydroxyl groups, and other raw material types, dosage ratios and preparation methods are the same as those in Embodiment 1.

[0100] Example 8

[0101] This embodiment provides a polyester hot melt adhesive, which is different from Example 1 only in that, in the raw materials for preparing the third polyester resin, the amount of polypropylene grafted maleic anhydride is increased, and the amount of dibasic acid is reduced, so that the mass ratio of dibasic acid, diol and polypropylene grafted maleic anhydride is 0.27:1:0.55, and other raw material types, dosage ratios and preparation methods are the same as those in Example 1.

[0102] Example 9

[0103] This embodiment provides a polyester hot melt adhesive, which differs from Embodiment 1 only in that the molar amount of the reactive group is ensured to remain unchanged, and in the raw materials for preparing the first polyester resin, the aromatic dibasic acid is terephthalic acid; the diol is 1,6-hexanediol; the polyamine is phenylenediamine, and other raw material types, dosage ratios and preparation methods are the same as those in Embodiment 1.

[0104] Comparative Example 1

[0105] This comparative example provides a polyester hot melt adhesive, which differs from Example 1 only in that no polyamine is included in the raw materials for preparing the first polyester resin, and the reduced polyamine is replaced by diols, and other raw material types, dosage ratios and preparation methods are the same as those in Example 1.

[0106] Comparative Example 2

[0107] This comparative example provides a polyester hot melt adhesive, which differs from Example 1 only in that the aromatic dibasic acid in the preparation raw materials of the first polyester resin is replaced by azelaic acid and succinic acid with equal molar amounts of carboxyl groups (mass ratio of 6:4), and other raw material types, dosage ratios and preparation methods are the same as those in Example 1.

[0108] Comparative Example 3

[0109] This comparative example provides a polyester hot melt adhesive, which differs from Example 1 only in that, in the raw materials for preparing the second polyester resin, octanediol is used to replace an equal molar amount of hydroxyl group in 1,4-butanediol, and other raw material types, dosage ratios and preparation methods are the same as those in Example 1.

[0110] Comparative Example 4

[0111] This comparative example provides a polyester hot melt adhesive, which differs from Example 1 only in that, in the raw materials for preparing the second polyester resin, octanediol replaces an equal molar amount of 1,4-butanediol, and succinic acid replaces an equal molar amount of suberic acid, and other raw material types, dosage ratios and preparation methods are the same as those in Example 1.

[0112] Comparative Example 5

[0113] This comparative example provides a polyester hot melt adhesive, which differs from Example 1 only in that, in the raw materials for preparing the third polyester resin, polypropylene grafted maleic anhydride replaces polyethylene grafted maleic anhydride with an equal molar amount of anhydride, and other raw material types, dosage ratios and preparation methods are the same as those in Example 1.

[0114] Comparative Example 6

[0115] This comparative example provides a polyester hot melt adhesive, which is different from Example 1 only in that the polyester hot melt adhesive includes 45 parts of a first polyester resin and 30 parts of a second polyester resin, and other raw material types, dosage ratios and preparation methods are the same as those in Example 1.

[0116] Comparative Example 7

[0117] This comparative example provides a polyester hot melt adhesive, which is different from Example 1 only in that the polyester hot melt adhesive includes 70 parts of a first polyester resin and 5 parts of a second polyester resin, and other raw material types, dosage ratios and preparation methods are the same as those in Example 1.

[0118] Comparative Example 8

[0119] This comparative example provides a polyester hot melt adhesive, which is different from Example 1 only in that the content of the third polyester resin is 40 parts, and other raw material types, dosage ratios and preparation methods are the same as those in Example 1.

[0120] Comparative Example 9

[0121] A commercially available hot melt adhesive product is Guangdong Suning New Materials 8085M.

[0122] Performance Testing

[0123] (1) Melt viscosity: tested in accordance with GB / T 1633 standard;

[0124] (2) Softening point: Tested in accordance with GB / T 2794;

[0125] (3) Curing time: Curing time test is carried out according to national standard HGT3716-2003;

[0126] (4) High and low temperature resistance and high and low temperature cycle performance test:

[0127] Polypropylene PP board glue coating test: After the hot melt adhesive samples provided in the examples and comparative examples are completely melted at 185°C, start gluing the PP board, and ensure that the surface of the substrate is clean during gluing. The amount of glue applied on the back of the PP board is 40gsm; test the 180° peeling force (tested in accordance with standard GB / T 2790), 120°C oven high temperature test (record the time when any phenomenon such as debonding, film shrinkage, edge warping occurs), -50°C low temperature resistance experiment (record the time when any phenomenon such as debonding, film shrinkage, edge warping occurs), -50°C ~ 120°C high and low temperature cyclic impact resistance (record the number of cycles when any phenomenon such as debonding, film shrinkage, edge warping occurs);

[0128] (5) Adhesion: Adhesion test standard is GB-9286-88; Note: 0 is the best and 5 is the worst;

[0129] In the present invention, 10 samples are tested for each test and the average value is taken; wherein, “-” means that it cannot be processed and cannot be tested.

[0130] The test results are shown in Table 1 and Table 2:

[0131] Table 1

[0132]

[0133]

[0134] Table 2

[0135]

[0136] It can be seen from Table 1 and Table 2 that the polyester hot melt adhesive provided by the present invention is compounded with three polyester resins with specific structures in specific contents, so that the polyester hot melt adhesive has excellent high temperature resistance and low temperature resistance, and will not have debonding, film shrinkage, warping and the like. It has good high and low temperature cycle resistance, low construction viscosity, good fit to a variety of substrates, and high adhesion. It can be seen from Examples 1 to 3 that the hot melt adhesive provided by the present invention has a low melt viscosity of 1200 to 1350 mPa.s at 180°C, and a softening point of 140 to 152°C; the 180° peel force is 121 to 125 N / 25cm, and it is resistant to high temperatures of 120°C and low temperatures of -50°C, and is cyclically impacted at -50 to 120°C for 48 to 55 times without debonding, film shrinkage, warping and the like.

[0137] It can be seen from Example 1 and Examples 4 to 6 and 9 that the first polyester resin does not have a specific raw material ratio or preparation method, and the mechanical properties or high temperature resistance of the hot melt adhesive are significantly reduced.

[0138] It can be seen from Examples 1 and 7 and 8 that the second and third polyester resins are not of specific raw material types or ratios, and the heat resistance of the hot melt adhesive is poor, and the resistance to thermal cycle shock is poor.

[0139] It can be seen from Example 1 and Comparative Examples 1 to 5 that the first polyester resin, the second polyester resin or the third polyester resin is not a specific structure, and the polyester hot melt adhesive has poor construction viscosity and high and low temperature resistance; or, has low adhesion to polypropylene and polystyrene substrates, which leads to easy debonding during high and low temperature resistance testing, resulting in poor high and low temperature resistance.

[0140] It can be seen from Example 1 and Comparative Examples 6 to 8 that the first polyester resin, the second polyester resin or the third polyester resin is not within a specific content range, and the comprehensive performance of the hot melt adhesive is poor; it can be seen from Comparative Example 9 that the polyester hot melt adhesive provided by the present invention has better performance than commercially available hot melt adhesives.

[0141] In summary, the polyester hot melt adhesive provided by the present invention is compounded by three polyester resins with specific structures in specific contents, and the raw materials of the three polyester resins are selected from specific types and proportions, so that the polyester hot melt adhesive has excellent high temperature resistance and low temperature resistance, good high and low temperature cycle resistance, low construction viscosity, good adhesion to a variety of substrates, and a wide range of applications.

[0142] The specific embodiments described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A polyester hot melt adhesive, characterized in that: In parts by weight, the polyester hot melt adhesive comprises 50 to 60 parts of a first polyester resin, 10 to 20 parts of a second polyester resin and 20 to 30 parts of a third polyester resin; The raw materials for preparing the first polyester resin include aromatic dibasic acid, diol and polyamine; The raw materials for preparing the second polyester resin include aliphatic dibasic acid and aliphatic long-chain diol; The raw materials for preparing the third polyester resin include dibasic acid, diol and polypropylene grafted maleic anhydride; In the raw material for preparing the second polyester resin, the carbon number of the aliphatic long-chain diol is 7 to 12; In the raw materials for preparing the first polyester resin, the mass ratio of the aromatic dibasic acid, the diol and the polyamine is 1:(0.7-1.2):(0.2-0.5).

2. The polyester hot melt adhesive according to claim 1, characterized in that: In the raw materials for preparing the first polyester resin, the aromatic dibasic acid includes at least one of terephthalic acid, phthalic acid or isophthalic acid.

3. The polyester hot melt adhesive according to claim 1, characterized in that: In the raw materials for preparing the first polyester resin, the diol includes at least one of 1,6-hexanediol, 1,4-butanediol or octanediol.

4. The polyester hot melt adhesive according to claim 1, characterized in that: The polyamines include aromatic polyamines and / or aliphatic polyamines.

5. The polyester hot melt adhesive according to claim 4, characterized in that: The polyamine includes at least one of phenylenediamine, dimethylpentanediamine, ethylenediamine or meta-xylylenediamine.

6. The polyester hot melt adhesive according to claim 1, characterized in that: The first polyester resin is prepared by the following method, which comprises: In the presence of a catalyst, an aromatic dibasic acid, a diol and a polyamine are mixed, and the first polyester resin is obtained through a first reaction and a second reaction.

7. The polyester hot melt adhesive according to claim 6, characterized in that: The temperature of the first reaction is 170-190° C. and the time is 1-3 hours.

8. The polyester hot melt adhesive according to claim 6, characterized in that: The temperature of the second reaction is 240-260° C. and the time is 1-3 hours.

9. The polyester hot melt adhesive according to claim 1, characterized in that: The glass transition temperature of the first polyester resin is 120-140°C.

10. The polyester hot melt adhesive according to claim 1, characterized in that: In the raw materials for preparing the second polyester resin, the aliphatic long-chain diol includes at least one of heptanediol, octanediol, nonanediol or decanediol.

11. The polyester hot melt adhesive according to claim 1, characterized in that: In the raw materials for preparing the second polyester resin, the carbon number of the aliphatic dibasic acid is 4-12.

12. The polyester hot melt adhesive according to claim 11, characterized in that: In the raw materials for preparing the second polyester resin, the aliphatic dibasic acid includes at least one of succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid or sebacic acid.

13. The polyester hot melt adhesive according to claim 1, characterized in that: The glass transition temperature of the second polyester resin is 20 to 30°C.

14. The polyester hot melt adhesive according to claim 1, characterized in that: In the raw materials for preparing the third polyester resin, the mass ratio of the dibasic acid, the diol and the polypropylene grafted maleic anhydride is (0.5-0.7):1:(0.15-0.45).

15. The polyester hot melt adhesive according to claim 1, characterized in that: In the raw materials for preparing the third polyester resin, the dibasic acid includes at least one of an aromatic dibasic acid, an aliphatic dibasic acid or an alicyclic dibasic acid.

16. The polyester hot melt adhesive according to claim 1, characterized in that: In the raw materials for preparing the third polyester resin, the diol includes an aliphatic diol.

17. The polyester hot melt adhesive according to claim 1, characterized in that: The glass transition temperature of the third polyester resin is 60-80°C.

18. The polyester hot melt adhesive according to claim 1, characterized in that: The polyester hot melt adhesive further comprises at least one of a tackifying resin, a silane coupling agent, a viscosity modifier or an antioxidant.

19. The polyester hot melt adhesive according to claim 18, characterized in that: In parts by weight, the polyester hot melt adhesive comprises 20 to 30 parts of a tackifying resin, 2 to 4 parts of a silane coupling agent, 10 to 20 parts of a viscosity regulator and 1 to 2 parts of an antioxidant.

20. The polyester hot melt adhesive according to claim 18, characterized in that: The tackifying resin includes at least one of rosin resin, C5 petroleum resin, C9 petroleum resin or terpene resin.

21. The polyester hot melt adhesive according to claim 18, characterized in that: The viscosity modifier includes polyethylene wax.

22. A method for preparing a polyester hot melt adhesive according to claim 1, characterized in that: The preparation method comprises: The first polyester resin, the second polyester resin and the third polyester resin are mixed and extruded to obtain the polyester hot melt adhesive.

23. The preparation method according to claim 22, characterized in that: The mixed material further comprises at least one of a tackifying resin, a silane coupling agent, a viscosity modifier or an antioxidant.

24. The preparation method according to claim 22, characterized in that: The mixing is carried out in a vibrating screen.

25. The preparation method according to claim 22, characterized in that: The extrusion is carried out in a twin-screw extruder.

26. The preparation method according to claim 25, characterized in that: The temperature of the first section of the twin-screw extruder is 140-160°C, the temperature of the second section is 190-210°C, the temperature of the third section is 250-270°C, and the temperature of the fourth section is 240-260°C.

27. A polypropylene sheet, characterized in that: The polypropylene sheet comprises the polyester hot melt adhesive as claimed in any one of claims 1 to 21.

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