High-washability hot-melt polyester as well as preparation method and application thereof

Abstract

The invention discloses a hot-melt polyester with high washing resistance, which is prepared from the following raw materials: a binary acid composition, a dihydric alcohol composition, an antioxidant and a catalyst, and the molar ratio of the binary acid composition to the dihydric alcohol composition is 1: (1.8-2.2). According to the invention, the hydrophobicity and structural stability of polyester can be obviously improved, so that the reflective layer is not easy to peel off in the washing process, and good bonding strength and retroreflection coefficient are maintained after washing. The retroreflection coefficient is 180-300 cd.lx <-1 >. M <-2 > and the bonding strength is 1.2-1.8 MPa after the reflective material is washed for 50 times by an ISO 15797-part4 method, so that the reflective material meets the requirements of keeping high washing resistance and high brightness from a common mark to a high-end protective reflective material, and has a wide application prospect.

Description

Technical Field

[0001] This invention relates to the field of adhesives, specifically to a highly washable hot-melt polyester, its preparation method, and its application. Background Technology

[0002] Reflective materials possess excellent retroreflective optical properties and are widely used in traffic signs, safety clothing, and other fields. Hot-melt polyester is a key component in reflective materials, and its performance significantly affects the overall performance of the material. Existing hot-melt polyester materials suffer from insufficient wash resistance; after repeated washing, the bonding strength decreases significantly, optical reflectivity is impaired, and the retroreflective coefficient of the reflective material decreases significantly, making it unsuitable for long-term outdoor use and frequent washing scenarios. Therefore, developing a hot-melt polyester with excellent wash resistance is crucial.

[0003] Chinese invention patent CN101724369B discloses a method for preparing a high-performance polyester hot melt adhesive. This method involves chemically grafting a synthesized copolyester hot melt adhesive with silane to obtain a hot melt adhesive product with high bonding strength and excellent resistance to washing and dry cleaning. However, the bonding performance significantly decreases after washing. Chinese invention patent application CN100439466C discloses a polyester hot melt adhesive and its preparation method. This method uses a metal salt of sorbic acid and an ethylene / acrylic acid copolymer to modify the copolymer. The resulting polyester hot melt adhesive exhibits high bonding strength and resistance to washing and dry cleaning, but its bonding performance with glass microspheres is poor, making it unsuitable for use in reflective materials. Summary of the Invention

[0004] In order to develop a hot-melt polyester with excellent water-wash resistance and good adhesion to glass microspheres, the first aspect of the present invention provides a hot-melt polyester with high water-wash resistance, wherein the raw materials include a combination of diacids, a combination of diols, an antioxidant, and a catalyst, wherein the molar ratio of the diacid combination and the diol combination is 1:(1.8-2.2).

[0005] Current hot-melt polyesters exhibit significantly reduced adhesion after washing, leading to microbead detachment and decreased reflectivity. In this invention, the diacid and diol combinations are used in a molar ratio of 1:(1.8-2.2), which significantly improves the hydrophobicity and structural stability of the polyester. This makes the reflective layer less prone to peeling during washing and maintains good adhesion strength and retroreflective coefficient after washing. The reason may be that the diacid combination synergistically optimizes the rigidity-flexibility balance of the polyester molecular chains, resulting in a more stable interfacial bond between the polyester and reflective microbeads. The diol combination synergistically allows the polyester to maintain sufficient flexibility while forming a dense molecular network structure, effectively resisting mechanical stress during washing. At a molar ratio of 1:(1.8-2.2), a cross-linked network structure with a balance of hydrophobicity, flexibility, and crystallinity is obtained, thus exhibiting excellent water resistance.

[0006] In one embodiment, the amount of antioxidant added is 0.001-0.005 wt% of the total amount of raw materials, the catalyst includes germanium oxide and zinc acetate, the amount of germanium oxide added is 1000-3000 ppm, and the amount of zinc acetate added is 3000-5000 ppm.

[0007] In one embodiment, the amount of germanium oxide added is 2000 ppm, and the amount of zinc acetate added is 4000 ppm.

[0008] In one embodiment, the dicarboxylic acid combination includes dimethyl terephthalate, isophthalic acid, and azelaic acid, wherein the weight ratio of dimethyl terephthalate, isophthalic acid, and azelaic acid is (330-380):(80-110):(18-28).

[0009] In one embodiment, the diol combination comprises neopentyl glycol, trimethylolpropane, and ethylene glycol, wherein the weight ratio of neopentyl glycol, trimethylolpropane, and ethylene glycol is (175-200):(14-22):(120-150).

[0010] As one embodiment, the high water-washable hot-melt polyester has a viscosity of 800-1100 mPa·s at 215°C, a viscosity of 1800-2500 mPa·s at 180°C, and a viscosity of 4200-6300 mPa·s at 150°C.

[0011] As one embodiment, the acid value of the high wash-resistant hot-melt polyester is <2mg KOH / g, and the hydroxyl value is 3-6mg KOH / g.

[0012] As one embodiment, the high wash-resistant hot-melt polyester has a retroreflective coefficient of 180-300 cd·lx after 50 washes using the ISO 15797-part 4 method. -1 ·m -2 The bonding strength is 1.2-1.8 MPa.

[0013] A second aspect of the present invention provides a method for preparing a highly washable hot-melt polyester, comprising the following steps: Preheat the mixture to 50-70℃, then introduce neopentyl glycol, ethylene glycol, antioxidant, and catalyst, and stir while heating. Add dimethyl terephthalate while stirring, and repeat the process three times by purging with nitrogen under vacuum. Distillation is carried out by heating up the temperature, and the temperature is lowered when the distillate decreases. After heating, add isophthalic acid, azelaic acid and trimethylolpropane, and purge with nitrogen under vacuum. Repeat three times. After a second distillation at elevated temperature, the acid value was found to be <5 mg KOH / g; Vacuuming to -830mbar to -110mbar and holding the pressure for 1-2 hours, followed by nitrogen pressurization, yields a highly washable hot-melt polyester.

[0014] In one embodiment, the jacket temperature of the single-stage distillation is 220-230°C, the top temperature is 60-70°C, and the kettle temperature is 190-200°C.

[0015] In one embodiment, the jacket temperature of the single-stage distillation is 225°C, the top temperature is 65°C, and the kettle temperature is 195°C.

[0016] In one embodiment, the jacket temperature of the secondary heating distillation is 250-270℃, the top temperature of the column is 90-100℃, and the kettle temperature is 220-240℃.

[0017] In one embodiment, the jacket temperature of the secondary heating distillation is 260°C, the top temperature of the column is 98°C, and the kettle temperature is 230°C.

[0018] As one embodiment, the preparation method of the high water-washable hot-melt polyester includes the following steps: Preheat the mixture to 60°C, then introduce neopentyl glycol, ethylene glycol, antioxidant, and catalyst. Heat the mixture to 80°C and stir at 15 rpm. Add dimethyl terephthalate while stirring at 50 rpm, and purge with nitrogen gas at -900 mbar under vacuum. Repeat three times. Distillation is carried out at a single temperature increase. When the distillate yield decreases, the temperature is lowered to 125°C. After heating to 150℃, add isophthalic acid, azelaic acid and trimethylolpropane, and repeat the process three times by purging with nitrogen under vacuum. After a second distillation at elevated temperature, the acid value was found to be <5 mg KOH / g; The high water-washable hot-melt polyester is obtained by evacuating to -830mbar to -110mbar, holding the pressure for 1-2 hours, and then pressurizing with nitrogen at 170-220℃.

[0019] A third aspect of the invention provides an application of a highly washable hot-melt polyester in reflective materials.

[0020] In one embodiment, the reflective material comprises, from top to bottom, glass microspheres, the aforementioned highly washable hot-melt polyester, and a base fabric.

[0021] Compared with the prior art, the present invention has the following beneficial effects: (1) The high water-washable hot melt polyester of the present invention adopts a molar ratio of 1: (1.8-2.2), which can significantly improve the hydrophobicity and structural stability of the polyester, making the reflective layer difficult to peel off during the water washing process, and maintaining good bonding strength and retroreflection coefficient after water washing.

[0022] (2) In the high water-washable hot melt polyester of the present invention, the dimethyl terephthalate, isophthalic acid and azelaic acid in the dicarboxylic acid combination adopt a weight ratio of (330-380): (80-110): (18-28), which can significantly improve the hydrophobicity and structural stability of the polyester, making the reflective layer less likely to peel off during the water washing process.

[0023] (3) In the high water-washable hot melt polyester of the present invention, the weight ratio of neopentyl glycol, trimethylolpropane and ethylene glycol in the diol combination is (175-200): (14-22): (120-150), which can control the degree of branching and crosslinking density, thereby improving the hydrolysis resistance and bonding strength of the polyester.

[0024] (4) The preparation method of the high water-washable hot melt polyester of the present invention controls the temperature of the transesterification stage reaction and the vacuum degree of the polycondensation stage, which can control the polyester to have a suitable molecular weight distribution and functional group content, so that the polyester has a narrow molecular weight distribution and a moderate end group content, forming a stable molecular network structure.

[0025] (5) The high wash-resistant hot-melt polyester of the present invention has a retroreflective coefficient of 180-300 cd·lx after being washed 50 times by the ISO 15797-part4 method. -1 ·m -2 With an adhesion strength of 1.2-1.8MPa, it meets the requirements of high water resistance and high brightness retention for everything from ordinary signs to high-end protective reflective materials, and has broad application prospects. Attached Figure Description

[0026] Figure 1 The surface condition of the high water-wash-resistant hot-melt polyester prepared in Example 1 after 50 water washes in reflective products.

[0027] Figure 2 The surface condition of the high water-wash-resistant hot-melt polyester prepared in Example 2 after 50 water washes in reflective products.

[0028] Figure 3 The surface condition of the high water-wash-resistant hot-melt polyester prepared in Example 3 after 50 water washes in reflective products.

[0029] Figure 4 A schematic diagram of the structure of the high water-washable hot-melt polyester prepared for the example, applied to reflective products.

[0030] Figure 4In the middle: 1. Glass microspheres; 2. Prepared high water-washable hot-melt polyester; 3. Base fabric. Detailed Implementation

[0031] Example 1 A highly washable hot-melt polyester is prepared from raw materials including 330 kg of dimethyl terephthalate, 110 kg of isophthalic acid, 28 kg of azelaic acid, 175 kg of neopentyl glycol, 14 kg of trimethylolpropane, 120 kg of ethylene glycol, 0.015 kg of antioxidant, and 0.0045 kg of catalyst.

[0032] The antioxidant is antioxidant 1010. The catalyst comprises 0.0015 kg of germanium oxide and 0.003 kg of zinc acetate.

[0033] A method for preparing a highly washable hot-melt polyester includes the following steps: Preheat the mixture to 60°C, then introduce neopentyl glycol, ethylene glycol, antioxidant, and catalyst. Heat the mixture to 80°C and stir at 15 rpm. Add dimethyl terephthalate while stirring at 50 rpm, and purge with nitrogen gas at -900 mbar under vacuum. Repeat three times. Distillation is carried out at a single temperature increase. When the distillate yield decreases, the temperature is lowered to 125°C. After heating to 150℃, add isophthalic acid, azelaic acid and trimethylolpropane, and repeat the process three times by purging with nitrogen under vacuum. After a second distillation at elevated temperature, the acid value was found to be <5 mg KOH / g; The high water-washable hot-melt polyester was obtained by evacuating to -110 mbar, holding the pressure for 1 hour, and then pressurizing with nitrogen at 195℃.

[0034] The jacket temperature for the first heating distillation is 225°C, the top temperature is 65°C, and the kettle temperature is 195°C.

[0035] The jacket temperature of the secondary heating distillation is 260°C, the top temperature of the column is 98°C, and the kettle temperature is 230°C.

[0036] An application of a highly washable, hot-melt polyester in reflective materials. (See structural schematic diagram.) Figure 4 .

[0037] The reflective material, from top to bottom, comprises glass microspheres 1, the aforementioned high water-washable hot-melt polyester 2, and a base fabric 3.

[0038] The reflective material was washed 50 times and the resulting photo shows its reflective properties. Figure 1 .

[0039] Example 2 A highly washable hot-melt polyester, the raw materials for which are prepared include 350 kg of dimethyl terephthalate, 95 kg of isophthalic acid, 22 kg of azelaic acid, 188 kg of neopentyl glycol, 18 kg of trimethylolpropane, 135 kg of ethylene glycol, 0.018 kg of antioxidant, and 0.0048 kg of catalyst.

[0040] The antioxidant is antioxidant 1010. The catalyst comprises 0.0016 kg of germanium oxide and 0.0032 kg of zinc acetate.

[0041] A method for preparing a highly washable hot-melt polyester includes the following steps: Preheat the mixture to 60°C, then introduce neopentyl glycol, ethylene glycol, antioxidant, and catalyst. Heat the mixture to 80°C and stir at 15 rpm. Add dimethyl terephthalate while stirring at 50 rpm, and purge with nitrogen gas at -900 mbar under vacuum. Repeat three times. Distillation is carried out at a single temperature increase. When the distillate yield decreases, the temperature is lowered to 125°C. After heating to 150℃, add isophthalic acid, azelaic acid and trimethylolpropane, and repeat the process three times by purging with nitrogen under vacuum. After a second distillation at elevated temperature, the acid value was found to be <5 mg KOH / g; The high water-washable hot-melt polyester was obtained by evacuating to -110 mbar, holding the pressure for 1 hour, and then pressurizing with nitrogen at 195℃.

[0042] The jacket temperature for the first heating distillation is 225°C, the top temperature is 65°C, and the kettle temperature is 195°C.

[0043] The jacket temperature of the secondary heating distillation is 260°C, the top temperature of the column is 98°C, and the kettle temperature is 230°C.

[0044] An application of a highly washable, hot-melt polyester in reflective materials. (See structural schematic diagram.) Figure 4 .

[0045] The reflective material, from top to bottom, comprises glass microspheres 1, the aforementioned high water-washable hot-melt polyester 2, and a base fabric 3.

[0046] The reflective material was washed 50 times and the resulting photo shows its reflective properties. Figure 2 .

[0047] Example 3 A highly washable hot-melt polyester, the raw materials for which are prepared include 380 kg of dimethyl terephthalate, 80 kg of isophthalic acid, 18 kg of azelaic acid, 200 kg of neopentyl glycol, 22 kg of trimethylolpropane, 150 kg of ethylene glycol, 0.020 kg of antioxidant, and 0.0048 kg of catalyst.

[0048] The antioxidant is antioxidant 1010. The catalyst comprises 0.0016 kg of germanium oxide and 0.0032 kg of zinc acetate.

[0049] A method for preparing a highly washable hot-melt polyester includes the following steps: Preheat the mixture to 60°C, then introduce neopentyl glycol, ethylene glycol, antioxidant, and catalyst. Heat the mixture to 80°C and stir at 15 rpm. Add dimethyl terephthalate while stirring at 50 rpm, and purge with nitrogen gas at -900 mbar under vacuum. Repeat three times. Distillation is carried out at a single temperature increase. When the distillate yield decreases, the temperature is lowered to 125°C. After heating to 150℃, add isophthalic acid, azelaic acid and trimethylolpropane, and repeat the process three times by purging with nitrogen under vacuum. After a second distillation at elevated temperature, the acid value was found to be <5 mg KOH / g; The high water-washable hot-melt polyester was obtained by evacuating to -110 mbar, holding the pressure for 1 hour, and then pressurizing with nitrogen at 195℃.

[0050] The jacket temperature for the first heating distillation is 225°C, the top temperature is 65°C, and the kettle temperature is 195°C.

[0051] The jacket temperature of the secondary heating distillation is 260°C, the top temperature of the column is 98°C, and the kettle temperature is 230°C.

[0052] An application of a highly washable, hot-melt polyester in reflective materials. (See structural schematic diagram.) Figure 4 .

[0053] The reflective material, from top to bottom, comprises glass microspheres 1, the aforementioned high water-washable hot-melt polyester 2, and a base fabric 3.

[0054] The reflective material was washed 50 times and the resulting photo shows its reflective properties. Figure 3 .

[0055] Performance testing 1. Viscosity: The viscosity of the high water-washable hot melt polyester prepared in Examples 1-3 was tested at 215℃, 180℃, and 150℃ using the HG / T 3660-1999 method.

[0056] 2. Water wash resistance: The reflective materials prepared in Examples 1-3 were washed 50 times with water using the method of ISO 15797-part 4, and then their performance was tested. The reflective materials prepared in Examples 1-3 showed the following performance after 50 washes: Figure 1-3 , Figure 1 The reflective material has a poor appearance after washing, with most of the glass microbeads falling off, making it suitable for general outdoor reflective signs. Figure 2The reflective material has a poor appearance after washing, with some glass microbeads falling off. It is suitable for high-visibility safety clothing and signage. Figure 3 The reflective material has a good appearance and high brightness after washing, making it suitable for professional protection and nautical and aviation markings that require ultra-high brightness and frequent washing.

[0057] The test results are shown in Table 1.

[0058] Table 1

Claims

1. A highly washable hot-melt polyester, characterized in that, The raw materials for preparation include a combination of diacids, a combination of diols, an antioxidant, and a catalyst, wherein the molar ratio of the diacid combination to the diol combination is 1:(1.8-2.2).

2. The high wash-resistant hot-melt polyester according to claim 1, characterized in that, The antioxidant is added at a rate of 0.001-0.005 wt% of the total raw materials. The catalyst includes germanium oxide and zinc acetate. The amount of germanium oxide added is 1000-3000 ppm, and the amount of zinc acetate added is 3000-5000 ppm.

3. The high wash-resistant hot-melt polyester according to claim 2, characterized in that, The dicarboxylic acid combination includes dimethyl terephthalate, isophthalic acid and azelaic acid, wherein the weight ratio of dimethyl terephthalate, isophthalic acid and azelaic acid is (330-380):(80-110):(18-28).

4. The high wash-resistant hot-melt polyester according to claim 3, characterized in that, The diol combination comprises neopentyl glycol, trimethylolpropane, and ethylene glycol, wherein the weight ratio of neopentyl glycol, trimethylolpropane, and ethylene glycol is (175-200):(14-22):(120-150).

5. The high wash-resistant hot-melt polyester according to claim 1, characterized in that, The high water-washable hot-melt polyester has a viscosity of 800-1100 mPa·s at 215°C, 1800-2500 mPa·s at 180°C, and 4200-6300 mPa·s at 150°C.

6. The high wash-resistant hot-melt polyester according to claim 1, characterized in that, The acid value of the high water-washable hot-melt polyester is <2 mg KOH / g, and the hydroxyl value is 3-6 mg KOH / g.

7. A method for preparing a high water-washable hot-melt polyester according to any one of claims 4-6, characterized in that, Includes the following steps: Preheat the mixture to 50-70℃, then introduce neopentyl glycol, ethylene glycol, antioxidant, and catalyst, and stir while heating. Add dimethyl terephthalate while stirring, and repeat the process three times by purging with nitrogen under vacuum. Distillation is carried out by heating up the temperature once, and the temperature is lowered when the distillate decreases. After heating, add isophthalic acid, azelaic acid and trimethylolpropane, and purge with nitrogen under vacuum. Repeat three times. After a second distillation at elevated temperature, the reaction continues once the acid value is found to be <5 mg KOH / g. Vacuuming to -830mbar to -110mbar and holding the pressure for 1-2 hours, followed by nitrogen pressurization, yields a highly washable hot-melt polyester.

8. The method for preparing the high wash-resistant hot-melt polyester according to claim 7, characterized in that, The jacket temperature for the first heating distillation is 220-230℃, the top temperature is 60-70℃, and the kettle temperature is 190-200℃.

9. The method for preparing the high wash-resistant hot-melt polyester according to claim 7, characterized in that, The jacket temperature of the secondary heating distillation is 250-270℃, the top temperature is 90-100℃, and the kettle temperature is 220-240℃.

10. An application of the high wash-resistant hot-melt polyester according to any one of claims 1-6, characterized in that, It is used in reflective materials.

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