Disulfide-containing polyester polyol, reactive polyurethane hot melt adhesive and preparation method of reactive polyurethane hot melt adhesive

Abstract

The invention discloses a disulfide-containing polyester polyol, a reactive polyurethane hot melt adhesive and a preparation method of the disulfide-containing polyester polyol, the disulfide-containing polyester polyol has a structural formula as shown in a formula (1), and in the formula (1), R is selected from C2-C10 alkylene; r1 is selected from alkylene with 1 to 8 carbon atoms, phenylene and benzylidene; and n is an integer from 1 to 26. The reactive polyurethane hot melt adhesive is prepared from disulfide-containing polyester polyol, crystalline polyester polyol, liquid polyester polyol, isocyanate, an adhesion promoter and a catalyst. The reactive polyurethane hot melt adhesive has the self-repairing performance, the mechanical property retention rate after self-repairing is high, the reactive polyurethane hot melt adhesive has the multi-time self-repairing performance, the self-repairing rate of the reactive polyurethane hot melt adhesive can still be kept at 80% or above after three times of repairing, and the reactive polyurethane hot melt adhesive has wide market prospects.

Description

Technical Field

[0001] This invention belongs to the field of reactive polyurethane hot melt adhesive technology. More specifically, this invention relates to a self-healing reactive polyurethane hot melt adhesive containing disulfide polyester polyol and its preparation method. Background Technology

[0002] Reactive polyurethane hot melt adhesives (PUR) mainly refer to polyurethane hot melt adhesives that use moisture in the air for cross-linking and curing. After curing, they have high bonding strength, good heat resistance, chemical resistance and durability. They can have good adhesion to substrates such as wood, ceramics, fabrics, metals, glass, plastics and rubber. In recent years, they have been rapidly developed in fields such as construction, automobiles, electronics, wood processing, bookbinding and food packaging.

[0003] The curing of PUR involves two stages. First, PUR is molten and applied to the substrate, then cooled and solidified to generate initial bond strength. Next, the -NCO in the system reacts with moisture in the air to achieve the final viscosity strength. Once PUR adhesives have fully cured and formed a cross-linked structure, they are typically difficult to disassemble. If the adhesive is damaged under external forces, it cannot be re-bonded, rendering the adhesive unusable and unrecyclable. These drawbacks limit the application of PUR.

[0004] By introducing disulfide bonds into PUR (polyurethane), which have low bond energy, are easily broken, and readily undergo reversible exchange dynamic equilibrium reactions, PUR can achieve self-healing under relatively mild conditions. However, in PURs that currently achieve self-healing through the introduction of disulfide bonds, the mechanical properties significantly decrease with increasing number of repair cycles. Summary of the Invention

[0005] Based on this, the purpose of the present invention is to provide a reactive polyurethane hot melt adhesive with multiple self-healing properties, and the mechanical properties of the hot melt adhesive are maintained at a high rate after each self-healing.

[0006] The specific technical solutions for achieving the above-mentioned objectives are as follows.

[0007] In a first aspect, the present invention provides a disulfide-containing polyester polyol having the structural formula shown in formula (1):

[0008]

[0009] Wherein, R is selected from: C2-C 10 Alkylene; R 1 Selected from: C1-C8 alkylene, phenylene, benzylene; n is an integer from 1 to 26.

[0010] In a second aspect, the present invention provides a disulfide-containing polyester polyol, which is obtained by reacting a dihydroxy disulfide of formula (2) with a dicarboxylic acid disulfide of formula (3) in a molar ratio of 1.03 to 2.01:1.

[0011]

[0012]

[0013] In equation (2), R is selected from: C2-C 10 Alkylene; R in formula (3) 1 Selected from: C1-C8 alkylene, phenylene, benzene.

[0014] A third aspect of the present invention provides the use of the above-mentioned disulfide-containing polyester polyol in the preparation of reactive polyurethane hot melt adhesives.

[0015] A fourth aspect of the present invention provides a method for preparing a disulfide-containing polyester polyol, comprising the following steps:

[0016] (1) The dihydroxy disulfide and the dicarboxy disulfide are put into a reaction vessel and heated under inert gas protection. After most of the materials have melted, the stirrer is started and heated until water begins to distill out.

[0017] (2) Continue heating until the water distillation rate stabilizes, then keep it warm until the distilled water reaches more than 60% of the theoretical output.

[0018] (3) Continue to heat to 180℃~310℃, while stirring at 100 rpm~130 rpm. When the distilled water reaches more than 95% of the theoretical output water, reduce the pressure to distill off the oligomers and excess dihydroxy disulfide and water generated by the reaction, and reduce the pressure to below 80 Pa. Continue the polycondensation reaction until the polymer acid value is less than 2 mg KOH / g.

[0019] (4) Under nitrogen protection, release the vacuum and discharge the material to obtain the product.

[0020] A fifth aspect of the present invention provides a reactive polyurethane hot melt adhesive, which is prepared from the following raw materials in parts by weight:

[0021] Contains 20 to 40 parts of disulfide polyester polyol

[0022] 10 to 30 parts of crystalline polyester polyol

[0023] 10 to 50 parts of liquid polyester polyol

[0024] 5 to 40 parts isocyanate

[0025] Adhesion accelerator 0.5 to 2 parts

[0026] Catalyst 0.01 to 0.2 parts.

[0027] A sixth aspect of the present invention provides a method for preparing a reactive polyurethane hot melt adhesive, comprising the following steps:

[0028] (1) The disulfide-containing polyester polyol, the crystalline polyester polyol, and the liquid polyester polyol are put into a reaction vessel and heated to 100°C~130°C. The mixture is then vacuum dehydrated for 60 minutes~180 minutes under stirring, with a vacuum degree of -0.095 MPa~0.05 MPa.

[0029] (2) Add the isocyanate and stir the mixture at 100°C to 130°C for 60 to 120 minutes under inert gas protection;

[0030] (3) Add the adhesive promoter and the catalyst in sequence, and stir and mix at 100℃~130℃ for 20 minutes to 40 minutes under inert gas protection;

[0031] (4) Maintain a constant temperature of 100℃~130℃, evacuate until no bubbles appear, and then discharge the material.

[0032] In this invention, a disulfide-containing polyester polyol with a specific disulfide bond content is prepared by polycondensation reaction of dihydroxy disulfide and dicarboxylic acid disulfide. This disulfide-containing polyester polyol is then combined with other raw materials in a certain ratio to prepare a reactive polyurethane hot melt adhesive. This reactive polyurethane hot melt adhesive has self-healing properties, high mechanical property retention rate after self-healing, and multiple self-healing capabilities. After three repairs, its adhesive strength retention rate can still be maintained at over 80%. In practical applications, when the adhesive surface of the bonded parts is damaged by external force, it can be re-bonded through its self-healing function, eliminating the need for adhesive removal, re-adhesion, and other repair processes, greatly saving costs and showing broad market prospects.

[0033] The preparation process of the reactive polyurethane hot melt adhesive of the present invention is simple, easy to operate, and easy to industrialize. Attached Figure Description

[0034] Figure 1 The infrared spectrum of the disulfide-containing polyester polyol SPD01 prepared in Example 1 of this invention is shown. Detailed Implementation

[0035] To facilitate understanding of the present invention, a more complete description will be provided below. The present invention can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a thorough and complete understanding of the disclosure of the present invention.

[0036] Unless otherwise defined, all technical and scientific terms used in this invention have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used in this specification is for the purpose of describing particular embodiments only and is not intended to limit the invention. The term "and / or" as used in this invention includes any and all combinations of one or more of the associated listed items.

[0037] In some embodiments of the present invention, a disulfide-containing polyester polyol is disclosed, having the structural formula shown in formula (1):

[0038]

[0039] Wherein, R is selected from: C2-C 10 Alkylene; R 1 Selected from: C1-C8 alkylene, phenylene, benzylene; n is an integer from 1 to 26.

[0040] In some embodiments, in formula (1), R is selected from: C2-C4 alkylene groups; R 1 Selected from: C1-C3 alkylene and phenylene.

[0041] In some embodiments, in formula (1), R is ethylene; R 1 It is a methylene group.

[0042] In some embodiments, the disulfide-containing polyester polyol has a viscosity of 500 mPa·s to 4500 mPa·s at 80°C.

[0043] In some embodiments, the disulfide-containing polyester polyol has a viscosity of 500 mPa·s to 1100 mPa·s at 80°C.

[0044] In some embodiments, the disulfide-containing polyester polyol has a viscosity of 500 mPa·s to 600 mPa·s at 80°C.

[0045] In some embodiments, the disulfide-containing polyester polyol has a viscosity of 540 mPa·s to 560 mPa·s at 80°C.

[0046] In some embodiments, the hydroxyl value of the disulfide-containing polyester polyol is 10 mg KOH / g to 112 mg KOH / g.

[0047] In some embodiments, the hydroxyl value of the disulfide-containing polyester polyol is 18 mg KOH / g to 60 mg KOH / g.

[0048] In some embodiments, the hydroxyl value of the disulfide-containing polyester polyol is 30 mg KOH / g to 60 mg KOH / g.

[0049] In some embodiments, the hydroxyl value of the disulfide-containing polyester polyol is 32 mg KOH / g to 33 mg KOH / g.

[0050] In some embodiments, the acid value of the disulfide-containing polyester polyol is 0.06 mg KOH / g to 0.20 mg KOH / g.

[0051] In some embodiments, the acid value of the disulfide-containing polyester polyol is 0.06 mg KOH / g to 0.16 mg KOH / g.

[0052] In some embodiments, the acid value of the disulfide-containing polyester polyol is 0.06 mgKOH / g to 0.08 mgKOH / g.

[0053] In some embodiments, the disulfide bond content of the disulfide-containing polyester polyol is 20 wt% to 45 wt%.

[0054] In some embodiments, the disulfide bond content of the disulfide-containing polyester polyol is 30 wt% to 45 wt%.

[0055] In some embodiments, the disulfide bond content of the disulfide-containing polyester polyol is 41 wt% to 43 wt%.

[0056] In other embodiments of the present invention, a disulfide-containing polyester polyol is disclosed, which is obtained by polycondensation reaction of a dihydroxy disulfide of formula (2) and a dicarboxylic acid disulfide of formula (3) in a molar ratio of 1.03 to 2.01:1.

[0057]

[0058]

[0059] In equation (2), R is selected from: C2-C 10 Alkylene; R in formula (3) 1 Selected from: C1-C8 alkylene, phenylene, benzene.

[0060] In some embodiments, in formula (2), R is selected from: C2-C4 alkylene groups; in formula (3), R... 1 Selected from: C1-C3 alkylene and phenylene.

[0061] In some embodiments, in formula (2), R is ethylene; in formula (3), R 1It is a methylene group.

[0062] In some embodiments, the dihydroxy disulfide is at least one of 2-hydroxyethyl disulfide, 3-hydroxypropyl disulfide, and 4-hydroxybutyl disulfide.

[0063] In some embodiments, the dicarboxylic disulfide is at least one of carboxymethyl disulfide, 2-carboxyethyl disulfide, 3-carboxypropyl disulfide, 3,3'-dicarboxydiphenyl disulfide, and 3,3'-dicarboxydibenzyl disulfide.

[0064] In other embodiments of the present invention, a method for preparing a disulfide-containing polyester polyol is disclosed, comprising the following steps:

[0065] (1) The dihydroxy disulfide and the dicarboxy disulfide are put into a reaction vessel and heated under inert gas protection. After most of the materials have melted, the stirrer is started and heated until water begins to distill out.

[0066] (2) Continue heating until the water distillation rate stabilizes, then keep it warm until the distilled water reaches more than 60% of the theoretical output.

[0067] (3) Continue to heat to 180℃~310℃, while stirring at 100 rpm~130 rpm. When the distilled water reaches more than 95% of the theoretical output water, reduce the pressure to distill off the oligomers and excess dihydroxy disulfide and water generated by the reaction, and reduce the pressure to below 80 Pa. Continue the polycondensation reaction until the polymer acid value is less than 2 mg KOH / g.

[0068] (4) Under nitrogen protection, release the vacuum and discharge the material to obtain the product.

[0069] In other embodiments of the present invention, the application of the above-mentioned disulfide-containing polyester polyol in the preparation of reactive polyurethane hot melt adhesives is disclosed.

[0070] In other embodiments of the present invention, a reactive polyurethane hot melt adhesive is disclosed, which is prepared from the following raw materials in parts by weight:

[0071] Contains 20 to 40 parts of disulfide polyester polyol

[0072] 10 to 30 parts of crystalline polyester polyol

[0073] 10 to 50 parts of liquid polyester polyol

[0074] 5 to 40 parts isocyanate

[0075] Adhesion accelerator 0.5 to 2 parts

[0076] Catalyst 0.01 to 0.2 parts.

[0077] In some embodiments, the reactive polyurethane hot melt adhesive is prepared from the following raw materials in parts by weight:

[0078] Contains 30 to 40 parts of disulfide polyester polyol

[0079] 20-30 parts of crystalline polyester polyol

[0080] 10 to 30 parts of liquid polyester polyol

[0081] 5 to 20 parts isocyanate

[0082] Adhesion accelerator 0.5 to 1.5 parts

[0083] Catalyst: 0.08 to 0.12 parts.

[0084] In some embodiments, the hydroxyl value of the crystalline polyester polyol is 10 mg KOH / g to 112 mg KOH / g.

[0085] In some embodiments, the hydroxyl value of the crystalline polyester polyol is 18 mg KOH / g to 60 mg KOH / g.

[0086] In some embodiments, the crystalline polyester polyol is Dynacoll with a hydroxyl value of 27 mg KOH / g to 34 mg KOH / g. ® Dynacoll with 7360 and hydroxyl values ​​of 27 mg KOH / g to 34 mg KOH / g ® 7380.

[0087] In some embodiments, the hydroxyl value of the liquid polyester polyol is 10 mg KOH / g to 112 mg KOH / g.

[0088] In some embodiments, the hydroxyl value of the liquid polyester polyol is 18 mg KOH / g to 60 mg KOH / g.

[0089] In some embodiments, the liquid polyester polyol is Dynacoll with a hydroxyl value of 27 mg KOH / g to 34 mg KOH / g. ® Dynacoll with 7230 and / or hydroxyl values ​​of 18 mg KOH / g to 24 mg KOH / g ® 7250.

[0090] In some embodiments, the isocyanate is one or more of 4,4'-diphenylmethane diisocyanate (MDI), carbodiimide-modified MDI, and MDI-50.

[0091] In some embodiments, the isocyanate is carbodiimide-modified MDI.

[0092] In some embodiments, the adhesion promoter is one or more of 3-isocyanate propyltriethoxysilane, 3-isocyanate propyltrimethoxysilane, 3-mercaptopropyltrimethoxysilane, and 3-mercaptopropyltriethoxysilane.

[0093] In some embodiments, the adhesion promoter is 3-isocyanate propyltrimethoxysilane.

[0094] In some embodiments, the catalyst is one or more of dibutyltin dilaurate (DBTDL), triethylenediamine, and dimorpholinodiethyl ether (DMDEE).

[0095] In some embodiments, the catalyst is dimorpholino diethyl ether (DMDEE).

[0096] In other embodiments of the present invention, a method for preparing a reactive polyurethane hot melt adhesive is disclosed, comprising the following steps:

[0097] (1) The disulfide-containing polyester polyol, the crystalline polyester polyol, and the liquid polyester polyol are put into a reaction vessel and heated to 100°C~130°C. The mixture is then vacuum dehydrated for 60 minutes~180 minutes under stirring, with a vacuum degree of -0.095 MPa~0.05 MPa.

[0098] (2) Add the isocyanate and stir the mixture at 100°C to 130°C for 60 to 120 minutes under inert gas protection;

[0099] (3) Add the adhesive promoter and the catalyst in sequence, and stir and mix at 100℃~130℃ for 20 minutes to 40 minutes under inert gas protection;

[0100] (4) Maintain a constant temperature of 100℃~130℃, evacuate until no bubbles appear, and then discharge the material.

[0101] In the following embodiments of the present invention, the crystalline polyester polyol was purchased from Evonik's Dynacoll. ® The 7300 series, specifically: Dynacoll ® 7360, hydroxyl value 27 mg KOH / g~34 mg KOH / g; Dynacoll ® 7380, with hydroxyl values ​​ranging from 27 mg KOH / g to 34 mg KOH / g. The liquid polyester polyol was purchased from Evonik's Dynacoll. ®The 7200 series, specifically: Dynacoll ® 7230, hydroxyl value between 27 mg KOH / g and 34 mg KOH / g; Dynacoll ® 7250, with hydroxyl values ​​ranging from 18 mg KOH / g to 24 mg KOH / g. 2-Hydroxyethyl disulfide (HES), 3-hydroxypropyl disulfide (HPS), 4-hydroxybutyl disulfide (HBS), carboxymethyl disulfide (CMS), 2-carboxyethyl disulfide (CES), 3-carboxypropyl disulfide (CPS), and 3,3'-dicarboxydiphenyl disulfide (CPHS) were purchased from Beijing Beilingwei Technology Co., Ltd. All other raw materials were commercially available products.

[0102] The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0103] Example 1: Preparation of disulfide-containing polyester polyols

[0104] This embodiment provides a disulfide-containing polyester polyol SPD01, the preparation method of which includes the following steps:

[0105] 1. Add 2-hydroxyethyl disulfide (HES) and carboxymethyl disulfide (CMS) (molar ratio: 9.05:8) to the reactor and heat slowly under nitrogen protection. After most of the materials have melted, start the stirrer and set the stirring speed to 75 rpm. When the temperature reaches 152℃, water begins to distill out.

[0106] 2. Continue heating to 176℃ (at which point the water distillation rate is relatively stable), keep warm for 75 minutes, until the output water reaches more than 60% of the theoretical output water;

[0107] 3. Continue heating to 200℃, while increasing the stirring speed to 100 rpm, and keep warm for 60 minutes. At this time, the water distilled will reach more than 95% of the theoretical output water. Reduce the pressure to below 80 Pa to distill off the oligomers and excess alcohol (unreacted HES or its condensation polymers) and water generated by the reaction. Continue the condensation reaction until the polymer acid value is less than 2 mg KOH / g.

[0108] 4. Finally, under nitrogen protection, the vacuum is released, and the material is discharged to obtain product SPD01.

[0109] The product SPD01 was subjected to infrared spectroscopy, and the results are as follows: Figure 1 As shown, from Figure 1 It can be seen that SPD01 at 3430cm -1 The characteristic absorption peak of the -OH group of alcohols appeared at 1728 cm⁻¹. -1 The characteristic absorption peak of the ester at -C=O appeared at 1260m. -1The characteristic absorption peak of the ester's -COC- appeared nearby, and also at 540 cm⁻¹. -1 The presence of the characteristic absorption peak -SS- indicates that the prepared SPD01 is a polyester polyol containing disulfide bonds.

[0110] The disulfide bond content of the disulfide polyester polyol SPD01 was found to be 42.6 wt%. According to HG / T 2709-1995, the hydroxyl value of the disulfide polyester polyol SPD01 was 32.5 mg KOH / g; according to HG / T 2708-1995, the acid value was 0.06 mg KOH / g; and according to GB / T 10247-2008, the viscosity (80℃) was 550 mPa·s.

[0111] Example 2 Preparation of disulfide-containing polyester polyols

[0112] This embodiment provides a disulfide-containing polyester polyol SPD02, the preparation method of which includes the following steps:

[0113] 1. Add 3-hydroxypropyl disulfide (HPS), 2-carboxyethyl disulfide (CES), and 3-carboxypropyl disulfide (CPS) (molar ratio: 6.72:4:1) to a reactor and heat slowly under nitrogen protection. After most of the materials have melted, start the stirrer and set the stirring speed to 80 rpm. When the temperature reaches 155°C, water begins to distill out.

[0114] 2. Continue heating to 178℃ (at which point the water distillation rate is relatively stable), keep warm for 80 minutes, until the output water reaches more than 60% of the theoretical output water;

[0115] 3. Continue heating to 203℃, while increasing the stirring speed to 105 rpm. When the effluent reaches more than 95% of the theoretical effluent, reduce the pressure to below 80 Pa to distill off the oligomers and excess alcohols (unreacted HPS or its condensation polymers) and water generated by the reaction. Continue the condensation reaction until the polymer acid value is less than 2 mg KOH / g.

[0116] 4. Finally, under nitrogen protection, the vacuum is released, and the material is discharged to obtain the product SPD02.

[0117] SPD02 has the same Figure 1 Similar infrared spectra indicate that the prepared SPD02 is a disulfide-containing polyester polyol.

[0118] The disulfide bond content of the disulfide polyester polyol SPD02 was found to be 30.2 wt%. According to HG / T 2709-1995, the hydroxyl value of the disulfide polyester polyol SPD02 was 58.6 mg KOH / g; according to HG / T 2708-1995, the acid value was 0.08 mg KOH / g; and according to GB / T 10247-2008, the viscosity (80℃) was 1070 mPa·s.

[0119] Example 3 Preparation of disulfide-containing polyester polyols

[0120] This embodiment provides a disulfide-containing polyester polyol SPD03, the preparation method of which includes the following steps:

[0121] 1. Add 4-hydroxybutyl disulfide (HBS) and 3,3'-dicarboxylic diphenyl disulfide (CPHS) (molar ratio: 13.03:12) into the reactor and heat slowly under nitrogen protection. After most of the materials have melted, start the stirrer and set the stirring speed to 100 rpm. When the temperature reaches 265℃, water begins to distill out.

[0122] 2. Continue heating to 277℃ (at which point the water distillation rate is relatively stable), keep warm for 90 minutes, until the output water reaches more than 60% of the theoretical output water;

[0123] 3. Continue heating to 305℃, while increasing the stirring speed to 125 rpm. When the effluent reaches more than 95% of the theoretical effluent, reduce the pressure to below 80 Pa to distill off the oligomers and excess alcohol (unreacted HBS or its condensation polymers) and water generated by the reaction. Continue the condensation reaction until the polymer acid value is less than 2 mg KOH / g.

[0124] 4. Finally, under nitrogen protection, the vacuum is released, and the material is discharged to obtain the product SPD03.

[0125] SPD03 has the same Figure 1 Similar infrared spectra indicate that the prepared SPD03 is a disulfide-containing polyester polyol.

[0126] The disulfide bond content of the disulfide polyester polyol SPD03 was tested to be 26.8 wt%. The hydroxyl value of the disulfide polyester polyol SPD03, tested according to HG / T 2709-1995, was 18.8 mg KOH / g; the acid value, tested according to HG / T 2708-1995, was 0.16 mg KOH / g; and the viscosity (80℃), tested according to GB / T 10247-2008, was 4280 mPa·s.

[0127] Reactive polyurethane hot melt adhesives were prepared using the disulfide-containing polyester polyols prepared in Examples 1-3. The raw materials used in Examples 4-8 and Comparative Examples 1-2 are shown in Table 2.

[0128] Table 2. Raw material ratios (parts by weight) in each embodiment and comparative example.

[0129]

[0130] Examples 4-8 and Comparative Examples 1-2 were prepared using the following method, differing only in the raw materials and their amounts:

[0131] (1) Add crystalline polyester polyol, liquid polyester polyol, and disulfide-containing polyester polyol (or 2-hydroxyethyl disulfide HES) into a reaction vessel, heat to 125°C, and vacuum dehydrate for 120 minutes with stirring. The vacuum degree is -0.095 MPa.

[0132] (2) Add isocyanate and stir at 125°C for 100 minutes under N2 protection;

[0133] (3) Add the adhesion promoter and catalyst in sequence, and stir and mix at 125°C for 30 minutes under N2 protection;

[0134] (4) Maintain a constant temperature of 125℃, evacuate until no bubbles appear, and then discharge the material.

[0135] Effect test

[0136] Initial sample preparation: Two standard adhesive polycarbonate (PC) substrates were dusted and degreased, and then horizontally bonded with the reactive polyurethane hot melt adhesive prepared in Examples 4-8 and Comparative Examples 1-2. The bonding area was 12.5 mm × 25 mm, and the adhesive thickness was 4 mm. After bonding, the samples were tested at 25°C.

[0137] Curing was carried out at 50%RH, and the complete curing condition was 25℃@50%RH×7d.

[0138] Preparation of repair samples at different temperatures: Take the initial sample prepared above, cut the adhesive layer horizontally with a blade, and then attach it according to the direction of the cut. Repair at room temperature (25℃), 40℃, 50℃ and 60℃ for 24 h respectively.

[0139] First repair sample preparation: Take the initial sample prepared above, cut the adhesive layer horizontally with a blade, and then attach it according to the direction of the cut. Repair at 60℃ for 24 h.

[0140] Second repair sample preparation: The adhesive layer of the first repair sample was cut horizontally with a blade, and then the sample was bonded together in the direction of the cut marks and repaired at 60℃ for 24 h.

[0141] Preparation of the third repair sample: The adhesive layer of the second repair sample was cut horizontally with a blade, and then bonded together in the direction of the cut. The sample was repaired at 60℃ for 24 h.

[0142] The tensile shear strength of the initial specimen and the repaired specimen was tested according to GB / T 7124-2008. The ratio of the tensile shear strength of the repaired specimen to that of the initial specimen is taken as the bond strength retention rate (self-healing rate).

[0143] The test results are shown in Table 3.

[0144] Table 3. Test results of relevant performance of reactive polyurethane hot melt adhesives in Examples 4-8 and Comparative Examples 1-4

[0145]

[0146] As can be seen from the performance comparison of Examples 4-8 and Comparative Examples 1-2 in Table 3:

[0147] The reactive polyurethane hot melt adhesive prepared without the addition of disulfide polyester polyol (Comparative Example 1) has no self-healing function. The reactive polyurethane hot melt adhesive prepared with the addition of the disulfide polyester polyol of the present invention has a better self-healing function. After three repairs, the self-healing rate does not decrease much, and the self-healing rate can still be maintained at more than 80% after the third repair.

[0148] In addition, heating helps to improve the self-healing rate within the same repair time. When adding the same amount of disulfide-containing polyester polyol, the reactive polyurethane hot melt adhesive prepared with a high disulfide content is more helpful in improving the self-healing rate than the reactive polyurethane hot melt adhesive prepared with a low disulfide content. Overall, the reactive polyurethane hot melt adhesive prepared in Example 7 has the best self-healing performance.

[0149] Although the reactive polyurethane hot melt adhesive (Comparative Example 2) prepared by adding only 2-hydroxyethyl disulfide (HES) (with the same disulfide bond content as in Example 7) also has a certain self-healing effect, its self-healing rate is much lower than that of the reactive polyurethane hot melt adhesive in Example 7. The first self-healing rate is less than 45%, and the third self-healing rate is only 32%.

[0150] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0151] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.

Claims

1. A bis-thio-polyester polyol characterized in that, It has a structural formula as shown in formula (1): wherein R is selected from: C2-C 10 alkylene; R 1 is selected from: C1-C8 alkylene, phenylene, benzylidene; n is an integer from 1 to 26.

2. The bis-thiopolyester polyol of claim 1, wherein, In formula (1), R is selected from the group consisting of C2-C4alkylene, preferably ethylene; R 1 is selected from the group consisting of C1-C3alkylene, phenylene, preferably methylene.

3. The bis-thiopolyester polyol of claim 1, wherein, The viscosity of the double-sulfur-containing polyester polyol at 80℃ is 500 mPa·s~4500 mPa·s, preferably 500 mPa·s~1100 mPa·s, preferably 500 mPa·s~600 mPa·s, more preferably 540 mPa·s~560 mPa·s; And / or, the hydroxyl value of the double-sulfur-containing polyester polyol is 10 mgKOH / g~112 mgKOH / g, preferably 18 mgKOH / g~60 mgKOH / g, preferably 30 mgKOH / g~60 mgKOH / g, more preferably 32 mgKOH / g~33 mgKOH / g; And / or, the acid value of the double-sulfur-containing polyester polyol is 0.06 mgKOH / g~0.20 mgKOH / g, preferably 0.06 mgKOH / g~0.16 mgKOH / g, more preferably 0.06 mgKOH / g~0.08 mgKOH / g; And / or, the double-sulfur bond content of the double-sulfur-containing polyester polyol is 20 wt%~45 wt%, preferably 30 wt%~45 wt%, more preferably 41 wt%~43 wt%.

4. A bis-thio-polyester polyol characterized in that, It is obtained by reacting a dihydroxy disulfide represented by formula (2) and a dicarboxylic disulfide represented by formula (3) with a molar ratio of 1.03~2.01:1: wherein R in formula (2) is selected from: C2-C4alkylene; preferably, R is selected from: C2-C4alkylene; more preferably, ethylene; and wherein R in formula (3) is selected from: C2-C4alkylene; preferably, R is selected from: C2-C4alkylene; more preferably, ethylene. 10 wherein R in formula (2) is selected from: C2-C4alkylene; R in formula (3) 1 is selected from the group consisting of C1-C8 alkylene, phenylene, benzylidene; preferably, R 1 is selected from the group consisting of C1-C3 alkylene, phenylene; more preferably methylene.

5. The bis-thiopolyol of claim 4, wherein, The dihydroxy disulfide is at least one of 2-hydroxyethyl disulfide, 3-hydroxypropyl disulfide, 4-hydroxybutyl disulfide, preferably 2-hydroxyethyl disulfide; And / or, the dicarboxylic disulfide is at least one of carboxymethyl disulfide, 2-carboxyethyl disulfide, 3-carboxypropyl disulfide, 3,3'-dicarboxylic diphenyl disulfide, 3,3'-dicarboxylic dibenzyl disulfide, preferably carboxymethyl disulfide.

6. Use of the double-sulfur-containing polyester polyol according to any one of claims 1~5 in the preparation of a reactive polyurethane hot melt adhesive.

7. A process for the preparation of a bi-thiopolyester polyol according to claim 4 or 5, characterized in that, Comprising the following steps: (1) Put the dihydroxy disulfide and the dicarboxylic disulfide into a reaction kettle, heat under inert gas protection, start the stirrer when most of the materials are dissolved, heat to start water distillation; (2) Continue heating until the distillation rate of water is stable, heat preservation until the distillation water reaches more than 60% of the theoretical water; (3) Continue to heat to 180℃~310℃, while the stirring speed is 100~130 rpm, when the distillation water reaches more than 95% of the theoretical water, evaporate the generated oligomers and excess dihydroxy disulfide and water under reduced pressure, and reduce the pressure to below 80 Pa, and the condensation reaction until the polymer acid value is less than 2 mg KOH / g; (4) Under nitrogen protection, release the vacuum, discharge, and obtain.

8. A reactive polyurethane hot melt adhesive characterized in that, It is prepared from the following raw materials by weight: The double-sulfur-containing polyester polyol according to any one of claims 1~5 20~40 parts Crystalline polyester polyol 10~30 parts Liquid polyester polyol 10~50 parts Isocyanate 5~40 parts adhesion promoter 0.5 parts to 2 parts catalyst 0.01 parts to 0.2 parts Preferably, the reactive polyurethane hot melt adhesive is prepared from the following raw materials by weight: bisulfide-containing polyester polyol 30 parts to 40 parts crystalline polyester polyol 20 parts to 30 parts liquid polyester polyol 10 parts to 30 parts isocyanate 5 parts to 20 parts adhesion promoter 0.5 parts to 1.5 parts catalyst 0.08 parts to 0.12 parts.

9. The reactive polyurethane hot melt adhesive according to claim 8, characterized in that, The crystalline polyester polyol has a hydroxyl number of 10 mgKOH / g to 112 mgKOH / g, preferably 18 mgKOH / g to 60 mgKOH / g, more preferably a hydroxyl number of 27 mgKOH / g to 34 mgKOH / g of Dynacoll ® 7360 and a hydroxyl number of 27 mgKOH / g to 34 mgKOH / g of Dynacoll ® 7380; and / or the liquid polyester polyol has a hydroxyl number of 10 mgKOH / g to 112 mgKOH / g, preferably of 18 mgKOH / g to 60 mgKOH / g, more preferably of 27 mgKOH / g to 34 mgKOH / g, preferably of Dynacoll 7230 and / or of Dynacoll 7250 ® 7230 and / or of Dynacoll 7250 ® 7250; and / or the isocyanate is one or more of 4,4'-diphenylmethane diisocyanate, carbodiimide-modified MDI, MDI-50, preferably carbodiimide-modified MDI; and / or the adhesion promoter is one or more of 3-isocyanate propyl triethoxysilane, 3-isocyanate propyl trimethoxysilane, 3-mercaptopropyl trimethoxysilane, 3-mercaptopropyl triethoxysilane, preferably 3-isocyanate propyl trimethoxysilane; and / or the catalyst is one or more of dibutyltin dilaurate, triethylenediamine, dimorpholinyl diethyl ether, preferably dimorpholinyl diethyl ether.

10. A method for producing the reaction-type polyurethane hot melt adhesive according to claim 8 or 9, characterized by, comprising the following steps: (1) The bisulfide-containing polyester polyol, the crystalline polyester polyol, and the liquid polyester polyol are put into a reaction kettle, heated to 100°C to 130°C, and dehydrated under vacuum for 60 minutes to 180 minutes with stirring, with a vacuum degree of -0.095 MPa to 0.05 MPa; (2) The isocyanate is added, and stirred at 100°C to 130°C for 60 minutes to 120 minutes under inert gas protection; (3) The adhesion promoter and the catalyst are added in sequence, and mixed at 100°C to 130°C for 20 minutes to 40 minutes under inert gas protection; (4) The temperature is kept at 100°C to 130°C, vacuum is applied until no bubbles appear, and the product is discharged.

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