Low-melting point polyester having adhesiveness

Abstract

This invention discloses a low-melting-point polyester with adhesive properties, relating to the field of polymer materials technology. The low-melting-point polyester with adhesive properties is composed of the following components in parts by weight: 55-75 parts of base polyester, 15-30 parts of comonomer, 3-10 parts of adhesion promoter, 0.5-2 parts of tackifier, and 0.5-1.5 parts of antioxidant. This invention, by introducing comonomer, disrupts the regularity and crystallinity of the polyester molecular chain, resulting in a significant decrease in the melting point of the polyester material; by adding adhesion promoter and tackifier, the adhesive properties of the polyester are enhanced from both chemical and physical dimensions.

Description

Technical Field

[0001] This invention relates to the field of polymer materials technology, specifically to a low-melting-point polyester with adhesive properties. Background Technology

[0002] Polyester, as an important synthetic fiber in the textile industry, is widely used due to its high strength, abrasion resistance, and good chemical stability. However, existing polyester fibers have significant shortcomings in melting point and bonding properties. Ordinary polyester has a melting point exceeding 250℃, requiring high temperatures for processes such as hot-melt bonding and fiber lamination. This not only results in high energy consumption but also easily leads to a decline in localized material properties. Furthermore, its poor bonding properties often necessitate the addition of adhesives in fiber lamination and fabric bonding applications, increasing production costs and potentially affecting the final product's performance and texture.

[0003] With the development of the textile industry, the performance requirements for polyester are increasing. Low-melting-point, high-adhesion polyester materials offer significant advantages in many fields, including nonwoven fabric production, hot melt adhesive coating, and garment composite fabrics. A low melting point reduces processing temperature, decreasing energy consumption and the risk of material thermal degradation; excellent adhesion eliminates the need for additional adhesives, simplifying processes and improving product durability and environmental friendliness. However, current polyester products on the market are still not perfect in terms of melting point and adhesion performance optimization, making it difficult to meet the modern industrial demand for efficient, energy-saving, and multifunctional materials.

[0004] Therefore, developing polyester materials that combine low melting point and good adhesion properties has become a key issue that urgently needs to be addressed in the textile technology field. This will not only effectively improve the limitations of existing polyester in heat treatment and bonding applications and expand its application range, but also inject new impetus into the sustainable development of the textile industry, helping the industry break through performance bottlenecks and move towards a higher level of development. Summary of the Invention

[0005] The purpose of this invention is to address the problems of excessively high melting point and insufficient adhesive properties of polyester in existing technologies, and to provide a low-melting-point polyester with adhesive properties and its preparation method, aiming to reduce processing temperature, simplify the process flow, and improve the durability of the product.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0007] A low-melting-point polyester with adhesive properties, comprising the following components in parts by weight: 55-75 parts base polyester, 15-30 parts comonomer, 3-10 parts adhesion promoter, 0.5-2 parts tackifier, and 0.5-1.5 parts antioxidant.

[0008] The antioxidant is a compound represented by Formula 1:

[0009] Formula 1: ;

[0010] In Formula 1, R1 is selected from: methyl, methoxy, cyano, and amino.

[0011] Furthermore, the base polyester is polyethylene terephthalate, with an intrinsic viscosity of 0.55-0.75 dL / g and a terminal carboxyl group content of ≤30 mol / t.

[0012] Furthermore, the comonomer is prepared by reacting sodium dimethyl isophthalate-5-sulfonate with ethylene glycol in a molar ratio of 1.1:1.

[0013] Furthermore, the preparation method of the comonomer is as follows: under a nitrogen atmosphere, sodium dimethyl isophthalate-5-sulfonate and 10 times the mass of sodium dimethyl isophthalate-5-sulfonate organic solvent are added to a reaction vessel, stirred until uniformly dispersed, and then ethylene glycol, zinc acetate, and zinc oxide are added. The temperature is raised to 160-200℃, and the reaction is carried out for 8-12 hours. After the reaction is completed, the organic phase is dried by rotary evaporation to obtain the comonomer.

[0014] Furthermore, the molar ratio of sodium dimethyl isophthalate-5-sulfonate, ethylene glycol, zinc acetate, and zinc oxide is 1.1:1:0.5-0.7:0.5-0.7.

[0015] Furthermore, the adhesion promoter is an ethylene-methyl acrylate copolymer.

[0016] Furthermore, the thickener is rosin glycerol ester.

[0017] Furthermore, the antioxidant is any one of the compounds shown in the following structures:

[0018] ;

[0019] .

[0020] A method for preparing low-melting-point polyester with adhesive properties includes the following steps:

[0021] (1) Raw material drying: The base polyester is placed in a drying device and dried at 120-150℃ for 2-4 hours, and the moisture content of the base polyester after drying is controlled to be ≤0.05%;

[0022] (2) Component mixing: Add the dried base polyester, comonomer, adhesion promoter, tackifier and antioxidant to a high-speed mixer and mix for 20-30 minutes at 250-260℃ and 800-1200r / min to obtain a uniform premix.

[0023] (3) Melt extrusion: The premixed material is added to a twin-screw extruder, and the extruder temperature parameters are set as follows: Zone 1 275-285℃, Zone 2 275-285℃, Zone 3 280-290℃, Die head temperature 285-295℃, screw speed 30-50r / min, and melt blending extrusion is carried out to obtain molten material;

[0024] (4) Granulation: The molten material is extruded through the die head of an extruder, cooled and shaped by cooling water at 20-30℃, and then cut into granules with a particle size of 2-4mm by a pelletizer to obtain low melting point polyester with adhesive properties.

[0025] Furthermore, the drying equipment in (1) is a vacuum dryer, and the vacuum degree is controlled to be -0.08 to -0.09 MPa during the drying process.

[0026] Furthermore, the component mixing in (2) adopts a staged mixing method: first, the base polyester and comonomer are mixed in a high-speed mixer at a speed of 800-1000r / min for 5-10 minutes, then the adhesion promoter, tackifier and antioxidant are added, and the speed is adjusted to 1000-1200r / min and mixing is continued for 15-20 minutes.

[0027] Furthermore, the process of pelletizing in (4) also includes a hot air drying step: the pellets are placed in a hot air drying oven and dried at 80-100℃ for 2-3 hours, and then sealed and packaged after cooling to room temperature.

[0028] The core mechanism of action of the antioxidant described in this invention is to inhibit the oxidative degradation of polyester materials during processing and long-term use, specifically achieved through the following key pathways:

[0029] ① Capturing free radicals and blocking oxidation chain reactions: When polyester is processed at high temperatures or exposed to oxygen and light for a long time, the molecular chains are prone to breakage, generating active free radicals. These free radicals continuously attack adjacent molecular chains, triggering chain growth and leading to yellowing and a decrease in mechanical properties (such as strength and toughness). The antioxidant molecule structure described in this invention contains an active hydrogen donor group, which can actively provide hydrogen atoms to active free radicals, converting highly active free radicals into stable molecules. At the same time, it forms its own highly stable, non-initiating antioxidant free radicals, thus blocking the continuous progress of oxidation chain reactions from the source.

[0030] ② Decomposition of hydroperoxides to avoid secondary initiation: Hydroperoxides are produced as intermediate products in oxidation chain reactions. Under high temperatures or the action of trace metal ions, they easily decompose into more destructive new free radicals, initiating secondary oxidation and accelerating material degradation. The antioxidants described in this invention can promote the decomposition of hydroperoxides into stable, non-free radical products through intramolecular electron transfer or group interactions, rather than generating new free radicals, thus reducing the risk of secondary degradation.

[0031] ③ Withstands high processing temperatures and maintains long-term antioxidant activity: The melt extrusion temperature of low-melting-point polyester is 220-230℃. The antioxidant of this invention contains sterically hindered groups in its molecules, which can protect the active functional regions within the molecules through steric effects, preventing them from being prematurely oxidized and destroyed at high processing temperatures. At the same time, the electronic effects of the antioxidant can regulate the antioxidant activity of the molecules, enabling it to efficiently inhibit high-temperature oxidation during the processing stage, and still slowly release antioxidant capacity during subsequent material use, thus extending the product's service life.

[0032] The base polyester in this invention serves as the material matrix, providing the inherent high strength, abrasion resistance, and chemical stability of polyester, ensuring the basic mechanical properties of the final fiber. The comonomer is the most crucial component for achieving the low melting point property. The introduction of sodium dimethyl isophthalate-5-sulfonate introduces sulfonic acid groups and meta-structures into the macromolecular chain, severely disrupting the regularity and crystallinity of the PET molecular chain. This reduced crystallinity directly leads to a significant decrease in the material's melting point, achieving the goal of low-temperature processing. As a chemical adhesive, the adhesion promoter possesses excellent polarity and reactivity. The methyl acrylate segments can generate stronger van der Waals forces, dipole-dipole interactions, and even potentially hydrogen bonds with other material surfaces. In the molten state, EMA can migrate to the interface. Through these stronger chemical forces, the chemical affinity and adhesion strength between the molten polyester and other adherends are greatly enhanced. Tackifiers, acting as physical adhesives, are natural resin-based tackifiers with very high viscosity after melting. They possess excellent wettability and viscosity. In blend systems, they effectively reduce the surface tension of the melt, making it easier to spread and penetrate into the tiny gaps and pores of the bonded materials, forming a strong physical-mechanical anchoring effect. Antioxidants, acting as protective agents, are crucial during melt blending and extrusion. Materials are exposed to high temperatures and shear forces, making them highly susceptible to thermal oxidative degradation, leading to molecular chain breakage and performance decline. Antioxidants effectively capture free radicals, terminating oxidative chain reactions and protecting all components from damage during critical processing, ensuring their designed functions are realized and guaranteeing the performance stability and appearance of the final product.

[0033] Compared with the prior art, the beneficial effects of the present invention are:

[0034] 1. The melting point is significantly reduced, which can effectively reduce the temperature in processing scenarios such as hot melt bonding and fiber composite, reduce processing energy consumption, and at the same time reduce the risk of thermal degradation of materials due to high temperature, thus solving the problem of high processing temperature of existing ordinary polyester.

[0035] 2. Significantly improved bonding performance, eliminating the need for additional adhesives to meet the requirements of fiber composites, fabric bonding, and other scenarios. This simplifies the production process, avoids the impact of additional adhesives on product performance and texture, and enhances product durability.

[0036] 3. Enhanced performance stability: During long-term use, antioxidants can effectively inhibit the oxidative degradation of materials, allowing the product to retain its mechanical properties well even after aging. At the same time, basic mechanical properties (such as strength and toughness) can also be maintained stably, meeting the needs of modern industry for long-term material use. Attached Figure Description

[0037] Figure 1 This is the NMR spectrum of antioxidant 1 as described in this invention. Detailed Implementation

[0038] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are merely some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0039] Preparation Example 1

[0040] Preparation of antioxidant 1:

[0041] ;

[0042] Step 1: Under a nitrogen atmosphere, add 15.00 g of starting material 1, 11.41 g of starting material 2, 10.88 g of sodium tert-butoxide, 0.52 g of tris(dibenzylacetone)dipalladium, 0.57 g of tri-tert-butylphosphine, and 200 ml of toluene solution to the reaction system. Stir until homogeneous, heat to 120 °C, and reflux for 12 h. After the reaction is complete, lower the temperature slightly, filter with diatomaceous earth to remove salts and catalysts. After cooling the filtrate to room temperature, wash three times with water, retaining the organic phase. Then extract the aqueous phase with ethyl acetate. Combine the organic phases and dry with anhydrous magnesium sulfate, removing the solvent using a rotary evaporator. Rotate to dryness, perform column chromatography, eluent with a mixture of petroleum ether and ethyl acetate, and rotate to dryness to obtain 16.20 g of intermediate 1. MS[MS+1] of intermediate 1: 386.

[0043] ;

[0044] Step 2: Under a nitrogen atmosphere, add 16.20 g of intermediate 1, 6.28 g of starting material 3, 17.41 g of anhydrous potassium carbonate, 1.46 g of tetra(triphenylphosphine)palladium, and 200 ml of toluene to the reaction system. Heat to 95 °C and reflux for 10 hours. Turn off the heat, cool to room temperature, allow to stand, and separate the phases. Extract the aqueous phase twice with ethyl acetate, combine the organic phases, dry the organic phase with anhydrous magnesium sulfate, filter, evaporate to dryness, and perform silica gel column chromatography using a mixture of petroleum ether and ethyl acetate as eluent. Evaporate to dryness to obtain 14.07 g of antioxidant 1. Antioxidant 1 mass spectrometry (MS[MS+1]): 442; Antioxidant 1 NMR (see attached image). Figure 1 .

[0045] Preparation Examples 2-4

[0046] In Preparation Examples 2-4, antioxidants 2-4 were prepared sequentially, following the same preparation method as in Preparation Example 1, except that raw material 3 was replaced, while the rest remained the same as in Preparation Example 1. See Table 1 for details.

[0047] Table 1.

[0048] Example 1

[0049] Preparation of a low-melting-point polyester with adhesive properties:

[0050] 1. Raw material mass ratio:

[0051] 65 parts of basic polyester, selected from polyethylene terephthalate, purchased from Shanghai Yuanye Biotechnology Co., Ltd.;

[0052] 20 parts of comonomer were selected from the reaction of sodium dimethyl isophthalate-5-sulfonate and ethylene glycol in a molar ratio of 1.1:1. Sodium dimethyl isophthalate-5-sulfonate was purchased from Shanghai Yien Chemical Technology Co., Ltd., and ethylene glycol was purchased from Shanghai Maclean Biochemical Technology Co., Ltd.

[0053] Six parts of adhesive accelerator were selected from ethylene-methyl acrylate copolymer (melt index of 3g / 10min (190℃ / 2.16kg), methyl acrylate (MA) content of 25%), and purchased from Wuxi Yiyuan New Material Technology Co., Ltd.

[0054] 1.5 parts of tackifier, selected from rosin glycerol ester, purchased from Jiangsu Aofu Biotechnology Co., Ltd.;

[0055] One part of antioxidant, selected from antioxidant 1 prepared in Preparation Example 1.

[0056] 2. Preparation method:

[0057] 2.1 Preparation of comonomers:

[0058] Under a nitrogen atmosphere, 1.1 mol of sodium dimethyl isophthalate-5-sulfonate and 10 times the mass of sodium dimethyl isophthalate-5-sulfonate organic solvent were added to the reactor. After stirring until uniformly dispersed, 1 mol of ethylene glycol, 0.5 mol of zinc acetate, and 0.5 mol of zinc oxide were added. The temperature was raised to 160°C and the reaction was carried out for 10 hours. After the reaction was completed, the organic phase was dried by rotary evaporation to obtain the comonomer.

[0059] 2.2 Preparation of a low-melting-point polyester with adhesive properties:

[0060] (1) Raw material drying: The base polyester was placed in a vacuum dryer and dried at 135°C and -0.085MPa vacuum for 3 hours. The moisture content of the base polyester after drying was 0.03%.

[0061] (2) Component mixing: A staged mixing method is adopted. At 255°C, the dried base polyester and comonomer are first mixed in a high-speed mixer at 900 r / min for 8 minutes. Then, the adhesion promoter, tackifier and antioxidant are added, and the speed is adjusted to 1100 r / min and the mixing is continued for 18 minutes to obtain a uniform premix.

[0062] (3) Melt extrusion: The premixed material is added to a twin-screw extruder, and the extruder temperature parameters are set as follows: Zone 1 280℃, Zone 2 280℃, Zone 3 285℃, Die head temperature 290℃, and screw speed 40 r / min. Melt blending extrusion is carried out to obtain molten material.

[0063] (4) Granulation: The molten material is extruded through the die head of an extruder, cooled and shaped by cooling water at 25°C, and then cut into granules with a particle size of 3mm by a pelletizer. The cut granules are placed in a hot air drying oven and dried at 90°C for 2.5 hours. After cooling to room temperature, they are sealed and packaged to obtain the adhesive low melting point polyester.

[0064] Examples 2-4

[0065] The preparation of a low-melting-point polyester with adhesive properties is carried out by referring to the preparation method of Example 1, except that the antioxidants are replaced sequentially with antioxidants 2-4 prepared in Preparation Examples 2-4, and the rest is the same as in Example 1.

[0066] Comparative Example 1

[0067] The preparation of an adhesive low-melting-point polyester is carried out according to the preparation method of Example 1, except that the antioxidant is replaced with antioxidant 1010 (CAS: 6683-19-8), and the rest is the same as in Example 1.

[0068] Comparative Example 2

[0069] The preparation of a low-melting-point polyester with adhesive properties is carried out according to the preparation method of Example 1, except that the antioxidant is replaced with antioxidant 1076 (CAS: 2082-79-3), and the rest is the same as in Example 1.

[0070] Comparative Example 3

[0071] The preparation of a low-melting-point polyester with adhesive properties is carried out according to the preparation method of Example 1, except that the antioxidant is not added, and the rest is the same as in Example 1.

[0072] Comparative Example 4

[0073] The preparation of a low-melting-point polyester with adhesive properties is carried out according to the preparation method of Example 1, except that the comonomer is not added, and the rest is the same as in Example 1.

[0074] Comparative Example 5

[0075] The preparation of a low-melting-point polyester with adhesive properties is carried out according to the preparation method of Example 1, except that the adhesive accelerator is not added, and the rest is the same as in Example 1.

[0076] Performance testing

[0077] 1. Melting point test:

[0078] According to GB / T 19466.3-2004 standard, the polyester fibers prepared in the examples and comparative examples were used as samples. Differential scanning calorimetry was used under a nitrogen atmosphere (flow rate 50 mL / min), with a heating rate of 10℃ / min. The test temperature range was 50℃-300℃, and the peak temperature of the melting peak was recorded as the melting point (Tm). Five parallel tests were performed, and the average value was taken. The data are shown in Table 2.

[0079] 2. Mechanical property testing:

[0080] According to GB / T 1040.3-2006 standard, the polyester granules in the examples and comparative examples were extruded into films with a thickness of 0.2-0.3 mm using a single-screw extruder. After cooling, they were cut into Type I standard tensile test specimens (effective width 10 mm, effective length 25 mm). Five specimens were prepared for each example and comparative example. The tensile strength (unit: MPa) and elongation at break (unit: %) of each specimen were recorded. The tests were performed in parallel for five times, and the average value was taken. The data are shown in Table 2.

[0081] 3. Tensile strength retention rate after aging:

[0082] The polyester fibers prepared in the examples and comparative examples were placed in a xenon lamp aging test chamber and exposed for 2500 hours. Then, their tensile strength was tested according to GB / T 1040.3-2006, and the tensile strength retention rate (%) was calculated. The data are shown in Table 2.

[0083] Exposure conditions: Radiation intensity: 0.35 W / m 2 (At 340nm wavelength); Temperature cycling: 60℃ (light stage) to 40℃ (dark stage), 8 hours of light + 4 hours of condensation (simulated rain) per cycle; Relative humidity: 50%±5% (light stage), 95%±5% (condensation stage).

[0084] Table 2.

[0085] Melting point Tm (°C) Tensile strength (MPa) Elongation at break (%) Tensile strength retention rate after aging (%) Example 1 120 54.6 170.3 96.5 Example 2 122 54.8 168.6 97.7 Example 3 118 55.2 172.3 98.3 Example 4 121 55.3 165.6 98.8 Comparative Example 1 120 54.7 150.2 72.2 Comparative Example 2 119 54.2 145.1 68.5 Comparative Example 3 120 55.6 135.8 35.8 Comparative Example 4 258 44.8 80.9 89.1 Comparative Example 5 120 46.7 92.2 89.4

[0086] As shown in Table 2, the low-melting-point polyester using specific antioxidants in the examples exhibits excellent overall performance: a significantly reduced melting point, facilitating low-temperature processing; good mechanical properties such as tensile strength and elongation at break, demonstrating high strength and toughness; and, particularly, a high tensile strength retention rate after aging tests, indicating that the antioxidants effectively inhibit oxidative degradation and improve durability. In contrast, the samples in the comparative examples lacking key components such as antioxidants or comonomers showed a trend of higher melting points, decreased mechanical properties, and lower performance retention rates after aging. This demonstrates that the present invention optimizes mechanical properties and aging resistance while reducing the melting point, reflecting the synergistic effect of each component.

[0087] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A low-melting-point polyester with adhesive properties, characterized in that, It is composed of the following components in parts by weight: 55-75 parts base polyester, 15-30 parts comonomer, 3-10 parts adhesion accelerator, 0.5-2 parts tackifier, and 0.5-1.5 parts antioxidant; The antioxidant is a compound represented by Formula 1: Formula 1: ; In Formula 1, R1 is selected from: methyl, methoxy, cyano, and amino.

2. The adhesive low-melting-point polyester according to claim 1, characterized in that, The base polyester is polyethylene terephthalate, with an intrinsic viscosity of 0.55-0.75 dL / g and a terminal carboxyl group content of ≤30 mol / t.

3. The adhesive low-melting-point polyester according to claim 1, characterized in that, The comonomer is prepared by reacting sodium dimethyl isophthalate-5-sulfonate with ethylene glycol in a molar ratio of 1.1:

1.

4. The low-melting-point polyester with adhesive properties according to claim 1, characterized in that, The adhesion promoter is an ethylene-methyl acrylate copolymer.

5. A low-melting-point polyester with adhesive properties as described in claim 1, characterized in that, The thickener is rosin glycerol ester.

6. A method for preparing a low-melting-point polyester with adhesive properties as described in any one of claims 1-5, characterized in that, Includes the following steps: (1) Raw material drying: The base polyester is placed in a drying device and dried at 120-150℃ for 2-4 hours, and the moisture content of the base polyester after drying is controlled to be ≤0.05%; (2) Component mixing: Add the dried base polyester, comonomer, adhesion promoter, tackifier and antioxidant to a high-speed mixer and mix for 20-30 minutes at 250-260℃ and 800-1200r / min to obtain a uniform premix. (3) Melt extrusion: The premixed material is added to a twin-screw extruder, and the extruder temperature parameters are set as follows: Zone 1 275-285℃, Zone 2 275-285℃, Zone 3 280-290℃, Die head temperature 285-295℃, screw speed 30-50r / min, and melt blending extrusion is carried out to obtain molten material; (4) Granulation: The molten material is extruded through the die head of an extruder, cooled and shaped by cooling water at 20-30℃, and then cut into granules with a particle size of 2-4mm by a pelletizer to obtain low melting point polyester with adhesive properties.

7. The method for preparing a low-melting-point polyester with adhesive properties according to claim 6, characterized in that, The drying equipment in (1) is a vacuum dryer, and the vacuum degree is controlled to be -0.08 to -0.09 MPa during the drying process.

8. The method for preparing a low-melting-point polyester with adhesive properties according to claim 6, characterized in that, The component mixing in (2) adopts a staged mixing method: first, the base polyester and comonomer are mixed in a high-speed mixer at a speed of 800-1000r / min for 5-10 minutes, then the adhesion promoter, tackifier and antioxidant are added, and the speed is adjusted to 1000-1200r / min and the mixing is continued for 15-20 minutes.

9. A method for preparing a low-melting-point polyester with adhesive properties according to claim 6, characterized in that, The process in (4) includes a hot air drying step after pelleting: the pellets are placed in a hot air drying oven and dried at 80-100℃ for 2-3 hours, and then sealed and packaged after cooling to room temperature.

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