A modified polyester hot melt adhesive and its preparation process

Abstract

The present invention belongs to the technical field of polymer materials. More specifically, it relates to a modified polyester hot melt adhesive and a preparation process thereof. The product prepared by the present invention includes the following raw materials in parts by weight: 95-100 parts of linear saturated polyester resin, 40-45 parts of composite filler, 8-12 parts of tackifying resin, 1-3 parts of plasticizer, 1-3 parts of microcrystalline wax, and 0.6-0.9 parts of antioxidant; wherein the composite filler includes: graphene oxide, nano-spherical silica and nano-calcium carbonate whiskers; the amount of the nano-spherical silica is 1.5-1.7 times the mass of the graphene oxide; the amount of the nano-calcium carbonate whiskers is 0.3-0.4 times the mass of the graphene oxide; in addition, the modified polyester hot melt adhesive also includes a thermoplastic elastomer of 8-10% of the mass of the linear saturated polyester resin.

Description

Technical Field

[0001] The present invention belongs to the technical field of polymer materials and more specifically relates to a modified polyester hot melt adhesive and a preparation process thereof. Background Art

[0002] Polyester hot melt adhesive is a kind of hot melt adhesive with excellent performance, high heat resistance, good weather resistance, water resistance and elasticity. However, when it is heated and melted, it has high viscosity and is difficult to operate manually. It usually requires special coating machinery for construction. In order to meet the needs of easy construction and bonding of different materials, it is generally modified.

[0003] The common modification methods currently include:

[0004] 1. Introducing reactive groups: By introducing reactive groups, such as carboxyl or hydroxyl, at the end of polyester molecules, they react with other active groups, such as polyisocyanate, anhydride-epoxy resin, peroxide or phenolic resin, to improve high-temperature adhesion, temperature resistance, water resistance and weather resistance;

[0005] 2. Polyether modification: Use medium molecular weight terephthalate or butylene glycol to form random copolymers, increase flexibility, reduce melting point and melt viscosity, and improve bonding strength;

[0006] 3. Silicone modification: By mixing silicone groups into the modified polyester to form an interpenetrating network, the chemical structure of the chain polyester resin is changed, thereby improving the thermal properties and bonding strength of the polyester;

[0007] 4. Bio-based polyester hot melt adhesive: Use bio-based raw materials such as 2,5-furandicarboxylic acid (FDCA), oil-based hydrogenated dimer acid and bio-based 1,4-butanediol to prepare fully bio-based polyester hot melt adhesive to improve environmental performance and reduce costs.

[0008] Through the above method, the corresponding performance of polyester hot melt adhesive can be improved to meet the needs of a wider range of industrial applications. Summary of the invention

[0009] The technical problem to be solved by the present invention is: for the commonly used polyester hot melt adhesive, adding fillers during reuse can improve its many properties, but due to the problem of its dispersion consistency and compatibility with the polyester hot melt adhesive, the crystallinity of the product cannot be effectively improved, and the hot melt processing viscosity is relatively high. The present invention provides a modified polyester hot melt adhesive and a preparation process thereof.

[0010] The purpose of the invention is to provide a modified polyester hot melt adhesive.

[0011] Another object of the present invention is to provide a process for preparing the modified polyester hot melt adhesive.

[0012] The above-mentioned purpose of the present invention is achieved through the following technical solutions:

[0013] A modified polyester hot melt adhesive comprises the following raw materials in parts by weight:

[0014] 95-100 parts linear saturated polyester resin

[0015] 40-45 parts of composite filler

[0016] 8-12 parts tackifying resin

[0017] 1-3 parts plasticizer

[0018] 1-3 parts microcrystalline wax

[0019] 0.6-0.9 parts antioxidant

[0020] Wherein, the composite filler comprises:

[0021] graphene oxide, nano-spherical silica, and nano-calcium carbonate whiskers;

[0022] The amount of the nano-spherical silicon dioxide is 1.5-1.7 times the mass of the graphene oxide;

[0023] The amount of the nano calcium carbonate whisker is 0.3-0.4 times the mass of the graphene oxide.

[0024] The beneficial effects brought by the above technical solution are as follows:

[0025] For the hot melt adhesive system composed of linear saturated polyester resin, the inventors found that the composite filler system composed of layered graphene oxide, spherical nano-silicon dioxide, and fibrous nano-calcium carbonate whiskers can effectively improve the crystallization uniformity and crystallization rate of the hot melt adhesive during use, thereby improving the mechanical properties of the material;

[0026] Specifically, the layered graphene oxide can provide a larger nucleation area, which helps to form more crystal nuclei, thereby increasing the crystallization rate; and the edges and interlayers of the graphene oxide have oxygen-containing functional groups, such as carboxyl, hydroxyl and epoxy groups, which provide polarity, while its conjugated region provides non-polarity, thereby making the graphene oxide have good dispersibility in the polyester hot melt adhesive system, and its polar functional groups provide binding sites with nano-spherical silica and nano-calcium carbonate whiskers, thereby assisting the uniform dispersion of the two in the polyester hot melt adhesive system;

[0027] Under the premise of uniform dispersion of the above fillers, the hot melt adhesive can be uniformly crystallized, reducing internal stress, thereby improving the toughness and impact strength of the material. The particle size of nano-spherical silica is smaller than that of graphene oxide, and its spherical structure allows it to crystallize radially, further promoting the uniformity of crystallization.

[0028] The fibrous nano-calcium carbonate whiskers can form directional nuclei in the polymer, which helps the directional crystallization of the material, thereby improving the uniform nucleation ability of the three-dimensional network structure together with the layered and spherical fillers.

[0029] Furthermore, the tackifying resin is selected from any one of rosin resin, terpene resin, C5 petroleum resin and C6 petroleum resin.

[0030] Furthermore, the plasticizer is selected from any one of tributyl citrate, epoxy soybean oil, dicyclohexyl phthalate, glycerol tribenzoate or trimethylolpropane tribenzoate.

[0031] Furthermore, the antioxidant is selected from any one of antioxidant BHT, antioxidant 801, butylated hydroxytoluene, and thiobis(3-methyl-6-tert-butyl)phenol.

[0032] Furthermore, the D50 of the graphene oxide is 120-150nm; the D50 of the nano-spherical silicon dioxide is 20-30nm, and the sphericity is 8.8-9.2; the average diameter of the nano-calcium carbonate whisker is 40-45nm, and the aspect ratio is 10-12.

[0033] Furthermore, an emulsifier is embedded between the graphene oxide layers, and the emulsifier is selected from any one of hexadecyltrimethylammonium bromide, sodium dodecylbenzenesulfonate, and emulsifier OP-10.

[0034] The beneficial effects of the above scheme are:

[0035] By further embedding an emulsifier between the graphene oxide layers, the interlayer spacing of the graphene oxide is widened, thereby exposing more active oxygen-containing functional groups, thereby improving the adsorption capacity for the other two fillers and further improving the overall dispersion uniformity;

[0036] In addition, during the use of hot melt adhesive, its wider interlayer spacing makes it easy for interlayer slippage to occur under the action of emulsifiers during the hot melt process, thereby effectively reducing the viscosity of the hot melt adhesive during use, improving the product processing performance and making it easier to spread on the substrate surface.

[0037] Furthermore, the modified polyester hot melt adhesive further comprises a thermoplastic elastomer accounting for 8-10% by mass of the linear saturated polyester resin.

[0038] Furthermore, the thermoplastic elastomer is selected from any one of TPU resin, TPEE resin, SBS resin, SIS resin, SEBS resin, SEPS resin, TPO resin and TPAE resin.

[0039] The beneficial effects of the above scheme are:

[0040] By further introducing thermoplastic elastomers into the polyester hot melt adhesive system, on the one hand, it can reduce the viscosity of the system after hot melting to a certain extent and improve the processing performance of the product; on the other hand, due to the introduction of polar fillers, the hot melt adhesive system may absorb moisture during actual use, causing moisture to continuously affect the hot melt adhesive system, thereby reducing the water resistance of the product. The introduction of thermoplastic elastomers can cause expansion after moisture enters the system, thereby closing the pores on the surface of the system and reducing the possibility of further diffusion of moisture inward, thereby improving the water resistance of the product.

[0041] A preparation process of a modified polyester hot melt adhesive, the specific preparation steps comprising:

[0042] Weigh each component according to the raw material composition;

[0043] In a nitrogen atmosphere, the linear saturated polyester resin and the antioxidant are first mixed and heated to melt, and then the tackifying resin and the composite filler are added. After shearing and mixing, the plasticizer and the microcrystalline wax are added, stirred and mixed, discharged, and cooled to obtain the modified polyester hot melt adhesive. DETAILED DESCRIPTION

[0044] The present invention is further described below with reference to specific examples, but the examples do not limit the present invention in any form. Unless otherwise specified, the reagents, methods and equipment used in the present invention are conventional reagents, methods and equipment in the art.

[0045] Unless otherwise specified, the reagents and materials used in the following examples are commercially available.

[0046] Example 1

[0047] Pretreatment of graphene oxide:

[0048] After the emulsifier and water are mixed in a mass ratio of 1:10, the mixture is stirred with a stirrer at a speed of 200 r / min for 20 minutes to fully dissolve the emulsifier, thereby obtaining an emulsifier aqueous solution;

[0049] The graphene oxide and the emulsifier aqueous solution were mixed in a mass ratio of 1:8, and the mixture was subjected to ultrasonic reaction at 70°C and an ultrasonic frequency of 120kHz for 45 minutes. The mixture was then allowed to stand at 4°C for 8 hours, and then filtered to collect the filter cake. The filter cake was transferred to an oven and dried at 100°C to a constant weight to obtain the pretreated graphene oxide.

[0050] The D50 of the graphene oxide is 120 nm;

[0051] The emulsifier is selected from hexadecyltrimethylammonium bromide;

[0052] Preparation of composite fillers:

[0053] The pretreated graphene oxide, nano-spherical silica and nano-calcium carbonate whiskers were mixed and poured into a 40% ethanol solution by mass, and ultrasonically dispersed for 20 minutes at a temperature of 45°C and an ultrasonic frequency of 60kHz, and then the pH was adjusted to 7.7, and then a silane coupling agent KH-560 was added, and then heated and stirred for reaction for 2 hours at a temperature of 55°C and a stirring speed of 300r / min, and then filtered to collect the filter cake, and the obtained filter cake was transferred to an oven and dried to constant weight at a temperature of 100°C to obtain a composite filler;

[0054] The amount of the nano-spherical silicon dioxide is 1.5 times the mass of the graphene oxide;

[0055] The amount of the nano calcium carbonate whiskers is 0.3 times the mass of the graphene oxide;

[0056] The amount of the pretreated graphene oxide is 10% of the mass of the ethanol solution;

[0057] The amount of the silane coupling agent KH-560 is 2% of the mass of the ethanol solution;

[0058] The D50 of the nano-spherical silicon dioxide is 20 nm, and the sphericity is 8.8; the average diameter of the nano-calcium carbonate whiskers is 40 nm, and the aspect ratio is 10;

[0059] In parts by weight, 95 parts of linear saturated polyester resin, 40 parts of composite filler, 8 parts of tackifying resin, 1 part of plasticizer, 1 part of microcrystalline wax, 0.6 parts of antioxidant, and 8% of the weight of the linear saturated polyester resin thermoplastic elastomer are taken in sequence;

[0060] The thermoplastic elastomer is selected from TPU resin;

[0061] In a nitrogen atmosphere, a linear saturated polyester resin, a thermoplastic elastomer and an antioxidant are first mixed and heated to melt, and then a tackifying resin and a composite filler are added, and after shear mixing at a speed of 4500 r / min for 45 minutes, a plasticizer and a microcrystalline wax are added, and the mixture is stirred and mixed at a speed of 600 r / min for 1 hour, the material is discharged, and cooled to obtain a modified polyester hot melt adhesive;

[0062] The tackifying resin is selected from rosin resin;

[0063] The plasticizer is selected from tributyl citrate;

[0064] The antioxidant is selected from the antioxidant BHT.

[0065] Example 2

[0066] Pretreatment of graphene oxide:

[0067] After the emulsifier and water are mixed in a mass ratio of 1:10, the mixture is stirred with a stirrer at a speed of 200 r / min for 20 minutes to fully dissolve the emulsifier, thereby obtaining an emulsifier aqueous solution;

[0068] The graphene oxide and the emulsifier aqueous solution were mixed in a mass ratio of 1:8, and the mixture was subjected to ultrasonic reaction at 75°C and an ultrasonic frequency of 130kHz for 50 minutes. The mixture was then allowed to stand at 5°C for 8 hours, and then filtered to collect the filter cake. The filter cake was transferred to an oven and dried at 100°C to a constant weight to obtain the pretreated graphene oxide.

[0069] The D50 of the graphene oxide is 130 nm;

[0070] The emulsifier is selected from sodium dodecylbenzene sulfonate;

[0071] Preparation of composite fillers:

[0072] The pretreated graphene oxide, nano-spherical silica and nano-calcium carbonate whiskers were mixed and poured into a 40% ethanol solution by mass, and ultrasonically dispersed for 20 minutes at a temperature of 45°C and an ultrasonic frequency of 60kHz, and then the pH was adjusted to 7.8, and then a silane coupling agent KH-560 was added, and then heated and stirred for reaction for 2 hours at a temperature of 55°C and a stirring speed of 300r / min, and then filtered to collect the filter cake, and the obtained filter cake was transferred to an oven and dried to constant weight at a temperature of 100°C to obtain a composite filler;

[0073] The amount of the nano-spherical silicon dioxide is 1.6 times the mass of the graphene oxide;

[0074] The amount of the nano calcium carbonate whiskers is 0.35 times the mass of the graphene oxide;

[0075] The amount of the pretreated graphene oxide is 12% of the mass of the ethanol solution;

[0076] The amount of the silane coupling agent KH-560 is 3% of the mass of the ethanol solution;

[0077] The D50 of the nano-spherical silicon dioxide is 25 nm, and the sphericity is 9; the average diameter of the nano-calcium carbonate whiskers is 42 nm, and the aspect ratio is 11;

[0078] In parts by weight, 98 parts of linear saturated polyester resin, 42 parts of composite filler, 10 parts of tackifying resin, 2 parts of plasticizer, 2 parts of microcrystalline wax, 0.8 parts of antioxidant, and 9% of the weight of the linear saturated polyester resin thermoplastic elastomer are taken in sequence;

[0079] The thermoplastic elastomer is selected from TPEE resin;

[0080] In a nitrogen atmosphere, a linear saturated polyester resin, a thermoplastic elastomer and an antioxidant are first mixed and heated to melt, and then a tackifying resin and a composite filler are added, and shear mixing is performed at a speed of 4800 r / min for 45 minutes, and then a plasticizer and a microcrystalline wax are added, and the mixture is stirred and mixed at a speed of 600 r / min for 1 hour, and the material is discharged and cooled to obtain a modified polyester hot melt adhesive;

[0081] The tackifying resin is selected from terpene resins;

[0082] The plasticizer is selected from citric epoxy soybean oil;

[0083] The antioxidant is selected from Antioxidant 801.

[0084] Example 3

[0085] Pretreatment of graphene oxide:

[0086] After the emulsifier and water are mixed in a mass ratio of 1:10, the mixture is stirred with a stirrer at a speed of 200 r / min for 20 minutes to fully dissolve the emulsifier, thereby obtaining an emulsifier aqueous solution;

[0087] The graphene oxide and the emulsifier aqueous solution were mixed in a mass ratio of 1:8, and the mixture was subjected to ultrasonic reaction at a temperature of 80°C and an ultrasonic frequency of 150kHz for 60 minutes. The mixture was then allowed to stand at a temperature of 6°C for 8 hours, and then filtered to collect the filter cake. The filter cake was transferred to an oven and dried at a temperature of 100°C to a constant weight to obtain the pretreated graphene oxide.

[0088] The D50 of the graphene oxide is 150 nm;

[0089] The emulsifier is selected from emulsifier OP-10;

[0090] Preparation of composite fillers:

[0091] The pretreated graphene oxide, nano-spherical silica and nano-calcium carbonate whiskers were mixed and poured into a 40% ethanol solution by mass, and ultrasonically dispersed for 20 minutes at a temperature of 45°C and an ultrasonic frequency of 60kHz, and then the pH was adjusted to 8.0, and then a silane coupling agent KH-560 was added, and then heated and stirred for reaction for 2 hours at a temperature of 55°C and a stirring speed of 300r / min, and then filtered to collect the filter cake, and the obtained filter cake was transferred to an oven and dried to constant weight at a temperature of 100°C to obtain a composite filler;

[0092] The amount of the nano-spherical silicon dioxide is 1.7 times the mass of the graphene oxide;

[0093] The amount of the nano calcium carbonate whiskers is 0.4 times the mass of the graphene oxide;

[0094] The amount of the pretreated graphene oxide is 15% of the mass of the ethanol solution;

[0095] The amount of the silane coupling agent KH-560 is 4% of the mass of the ethanol solution;

[0096] The D50 of the nano-spherical silicon dioxide is 30 nm, and the sphericity is 9.2; the average diameter of the nano-calcium carbonate whiskers is 45 nm, and the aspect ratio is 12;

[0097] In parts by weight, 100 parts of linear saturated polyester resin, 45 parts of composite filler, 12 parts of tackifying resin, 3 parts of plasticizer, 3 parts of microcrystalline wax, 0.9 parts of antioxidant, and 10% of the weight of the thermoplastic elastomer of the linear saturated polyester resin are taken in sequence;

[0098] The thermoplastic elastomer is selected from SBS resin;

[0099] In a nitrogen atmosphere, a linear saturated polyester resin, a thermoplastic elastomer and an antioxidant are first mixed and heated to melt, and then a tackifying resin and a composite filler are added, and shear mixing is performed at a speed of 5000 r / min for 45 minutes, and then a plasticizer and a microcrystalline wax are added, and the mixture is stirred and mixed at a speed of 600 r / min for 1 hour, and the material is discharged and cooled to obtain a modified polyester hot melt adhesive;

[0100] The tackifying resin is selected from C5 petroleum resin;

[0101] The plasticizer is selected from dicyclohexyl phthalate;

[0102] The antioxidant is selected from butylated hydroxytoluene.

[0103] Example 4

[0104] The present embodiment differs from the embodiment 1 in that no thermoplastic elastomer is added and the other conditions remain unchanged.

[0105] Example 5

[0106] Compared with Example 1, this embodiment differs in that no emulsifier is added, and other conditions remain unchanged.

[0107] Comparative Example 1

[0108] The difference between this comparative example and Example 1 is that no nano calcium carbonate whiskers are added, and the other conditions remain unchanged.

[0109] Comparative Example 2

[0110] The difference between this comparative example and Example 1 is that no nano-spherical silica is added, and the other conditions remain unchanged.

[0111] Comparative Example 3

[0112] The difference between this comparative example and Example 1 is that no pretreated graphene oxide is added, and the other conditions remain unchanged.

[0113] The performance tests were performed on the products obtained in the examples and comparative examples. The specific test methods and test results are as follows:

[0114] The products obtained in the above-mentioned embodiments and comparative examples were hot-pressed in a flat vulcanizer using a mold having a thickness of 0.12 mm to obtain a hot melt adhesive film having a specification of 500 mm×500 mm×0.12 mm;

[0115] Poplar veneers with a size of 500mm×500mm×2.5mm and a moisture content of 6% were used; 3 poplar veneers were taken, and the poplar board blanks were matched according to the criss-cross texture, and hot-melt adhesive films were placed on both sides of the poplar veneers to form a plywood, and the bio-based polyester hot-melt adhesive poplar three-layer plywood was obtained by high-temperature hot pressing, the hot pressing temperature was 165°C, the hot pressing pressure was 1.5MPa, and the hot pressing time was 90s / mm.

[0116] The plywood obtained from the above different embodiments and comparative examples was tested for performance, and the specific testing method is as follows:

[0117] After the prepared plywood was placed at room temperature for 7 days, it was tested according to the analysis method of bonding strength and internal bonding strength of Class I plywood in GB / T 17657-2022 "Test methods for physical and chemical properties of wood-based panels and veneered wood-based panels" to obtain the bonding strength of the plywood after boiling (100°C) and the internal bonding strength;

[0118] The specific test results are shown in Table 1;

[0119] Table 1: Product performance test results

[0120] Bonding strength / MPa Internal bonding strength / MPa Example 1 1.22 0.98 Example 2 1.20 0.97 Example 3 1.24 0.99 Example 4 0.62 0.93 Example 5 1.15 0.94 Comparative Example 1 0.78 0.87 Comparative Example 2 0.80 0.89 Comparative Example 3 0.73 0.91

[0121] It can be seen from the test results in Table 1 that the product obtained by the present invention not only has excellent bonding performance, but also has good water resistance.

[0122] The above embodiments are preferred implementation modes of the present invention, but the implementation modes of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications that do not deviate from the spirit and principles of the present invention should be equivalent replacement methods and are included in the protection scope of the present invention.

Claims

1. A modified polyester hot melt adhesive, characterized in that: The invention comprises the following raw materials in parts by weight: 95-100 parts linear saturated polyester resin 40-45 parts of composite filler 8-12 parts tackifying resin 1-3 parts plasticizer 1-3 parts microcrystalline wax 0.6-0.9 parts antioxidant And, a thermoplastic elastomer containing 8-10% by mass of the linear saturated polyester resin; The thermoplastic elastomer is selected from any one of TPU resin, TPEE resin, SBS resin, SIS resin, SEBS resin, SEPS resin, TPO resin and TPAE resin; Wherein, the composite filler comprises: graphene oxide, nano-spherical silica, and nano-calcium carbonate whiskers; The amount of the nano-spherical silicon dioxide is 1.5-1.7 times the mass of the graphene oxide; The amount of the nano calcium carbonate whisker is 0.3-0.4 times the mass of the graphene oxide.

2. A modified polyester hot melt adhesive according to claim 1, characterized in that: The tackifying resin is selected from any one of rosin resin, terpene resin, C5 petroleum resin and C6 petroleum resin.

3. The modified polyester hot melt adhesive according to claim 1, characterized in that: The plasticizer is selected from any one of tributyl citrate, epoxy soybean oil, dicyclohexyl phthalate, glycerol tribenzoate or trimethylolpropane tribenzoate.

4. The modified polyester hot melt adhesive according to claim 1, characterized in that: The antioxidant is selected from any one of antioxidant BHT, antioxidant 801, butylated hydroxytoluene, and thiobis(3-methyl-6-tert-butyl)phenol.

5. The modified polyester hot melt adhesive according to claim 1, characterized in that: The D50 of the graphene oxide is 120-150nm; the D50 of the nano-spherical silicon dioxide is 20-30nm, and the sphericity is 8.8-9.2; the average diameter of the nano-calcium carbonate whisker is 40-45nm, and the aspect ratio is 10-12.

6. A modified polyester hot melt adhesive according to any one of claims 1 or 5, characterized in that: An emulsifier is embedded between the graphene oxide layers, and the emulsifier is selected from any one of hexadecyltrimethylammonium bromide, sodium dodecylbenzenesulfonate, and emulsifier OP-10.

7. A process for preparing the modified polyester hot melt adhesive according to any one of claims 1 to 6, characterized in that: The specific preparation steps include: Weigh each component according to the raw material composition; In a nitrogen atmosphere, the linear saturated polyester resin, thermoplastic elastomer and antioxidant are first mixed and heated to melt, and then the tackifying resin and composite filler are added. After shearing and mixing, the plasticizer and microcrystalline wax are added, stirred and mixed evenly, discharged, and cooled to obtain the modified polyester hot melt adhesive.