Degradable boiling-water-resistant hot melt adhesive copolyester material as well as preparation method and application thereof

Abstract

The invention provides a degradable boiling-water-resistant hot melt adhesive copolyester material as well as a preparation method and application thereof, and belongs to the technical field of copolyester hot melt adhesives. The invention discloses a high-temperature-resistant flame-retardant polyester resin which is prepared from the following raw materials in parts by mole: 1 part of 1, 4-butanediol, 0.35 part of adipic acid, 0.35 part of terephthalic acid, 0.03 part of (R, S)-1, 2, 3, 4-butanetetraol, 0.012 part of tetrabutyl titanate and 0.001-0.005 part of montmorillonite. According to the hot melt adhesive, bio-based copolyester is used as a matrix, absolute ethyl alcohol is used for modifying the surface of montmorillonite, the surface of montmorillonite is coated with rich alcoholic hydroxyl groups, a main matrix copolyester material and the modified montmorillonite are fully blended at 170 DEG C, functional groups such as carboxyl and hydroxyl groups on the surface of the material form a hydrogen bond cross-linked network in the hot melt adhesive, and the hot melt adhesive is prepared. Meanwhile, the inorganic filler forms a hydrophobic layer on the surface of the adhesive, so that mechanical interlocking occurs on the wood surface, and permeation of water molecules is effectively isolated. Compared with other bio-based adhesives, the bio-based adhesive has the characteristics of high strength, good stability, excellent water resistance and the like.

Description

Technical Field

[0001] The invention relates to the field of polymer materials, and in particular to a degradable boiling water resistant hot melt adhesive copolyester material and a preparation method and application thereof. Background Art

[0002] Hot melt adhesive originally uses asphalt, rosin and paraffin as raw materials. It is solid at room temperature and becomes liquid through high-temperature melting. It is evenly applied to the bonding surface of plywood and can be used to bond different materials after pressing and cooling.

[0003] Hot melt adhesives can be divided into polyurethane, polyamide, EVA, polyester and block copolymer according to the base type. Among them, polyester has attracted attention due to its good weather resistance, thermal stability and bonding strength. The base of traditional polyester hot melt adhesives is mostly polylactide and polycaprolactone.

[0004] The vigorous development of industrialization and the continuous strengthening of environmental awareness have led to the transformation of traditional polyester hot melt adhesives to bio-based polyester hot melt adhesives, and further preparation of functional products. However, traditional bio-based polyester hot melt adhesives have defects such as high viscosity under melting conditions, too fast cooling time, and too fast viscosity drop under high temperature and humidity environments, which put forward higher requirements for hot melt adhesives in actual production. To this end, we have solved the problems of high viscosity and too fast cooling time of bio-based polyester hot melt adhesives during melting processing while ensuring its application in high temperature and humidity environments. Summary of the invention

[0005] The present invention provides a degradable boiling water resistant hot melt adhesive copolyester material to solve the technical problems of high viscosity and fast cooling time during the melt processing of bio-based polyester hot melt adhesive. The present invention introduces (R,S)-1,2,3,4-butanetetrol and adipic acid into the polyester chain, which effectively alleviates the problem of too fast cooling and solidification during the melt processing of the hot melt adhesive while enhancing the lap strength; the addition of an appropriate amount of inorganic filler improves the mechanical properties and bonding stability of the composite material.

[0006] In order to solve the above technical problems, the technical solution adopted by the present invention is: a degradable boiling water resistant hot melt adhesive copolyester material is prepared from the following raw materials in the following molar proportions: 1 part of 1,4-butanediol, 0.35 parts of adipic acid, 0.35 parts of terephthalic acid, 0.03 parts of (R,S)-1,2,3,4-butanetetrol, 0.012 parts of tetrabutyl titanate, and 0.001 to 0.005 parts of montmorillonite.

[0007] The present invention also provides a method for preparing the above-mentioned degradable boiling water resistant hot melt adhesive copolyester material, comprising the following steps:

[0008] A1. Add 1,4-butanediol, adipic acid and (R,S)-1,2,3,4-butanetetrol in a molar distribution ratio into a three-necked flask in sequence and heat to raise the temperature. Add tetrabutyl titanate as a catalyst dropwise into the three-necked flask, stir at a uniform speed and introduce nitrogen for protection. The polymerization reaction is carried out for 2-3 hours to obtain an oligomer polyester.

[0009] A2. Add terephthalic acid to a three-necked flask containing oligomer polyester, react for 1 hour, then drop tetrabutyl titanate as a catalyst, and polymerize for 2-3 hours to obtain a low molecular weight mixed polyester;

[0010] A3, adding low molecular weight mixed polyester and catalyst tetrabutyl titanate into a three-necked flask protected by nitrogen and stirring, heating the three-necked flask to raise the temperature, polycondensation reaction for 3-4 hours, evacuating the three-necked flask until the internal pressure is lower than 300 Pa, keeping the temperature for reaction for 1-2 hours, reducing the viscous copolyester to room temperature, filtering and purifying in tetrachloroethane to obtain the copolyester;

[0011] A4. The copolyester and nano-montmorillonite are fully blended and added into the extruder. The temperature of the extruder is increased to 225-230°C. The material is discharged through water cooling and traction. After being completely cooled, it is crushed and passed through a 100-mesh sieve to obtain the final product, a degradable boiling water-resistant hot melt adhesive copolyester material.

[0012] As a further limitation of the technical solution of the present invention, in step A1, the temperature is increased to 170-190° C. to carry out the polymerization reaction.

[0013] As a further limitation of the technical solution of the present invention, in step A3, the temperature is increased to 225-230° C. to carry out the polycondensation reaction.

[0014] As a further limitation of the technical solution of the present invention, the molar ratio of the added catalyst tetrabutyl titanate in steps A1, A2 and A3 is 2:2:1.

[0015] In addition, the present invention also provides a use of the above-mentioned degradable boiling water resistant hot melt adhesive copolyester material in bonding the surface of poplar wood boards.

[0016] Compared with the prior art, the present invention has the following beneficial effects:

[0017] The hot melt adhesive copolyester material of the present invention uses bio-based copolyester as the matrix, and uses anhydrous ethanol to modify the surface of montmorillonite so that its surface is coated with abundant alcohol hydroxyl groups. The main matrix copolyester material and the modified montmorillonite are fully blended at 170°C, and the functional groups such as carboxyl and hydroxyl groups on the surface of the material form a hydrogen bond cross-linking network in the hot melt adhesive. At the same time, the inorganic filler forms a hydrophobic layer on the surface of the adhesive, which effectively isolates the penetration of water molecules while mechanically interlocking on the wooden surface. Compared with other bio-based adhesives, it has the characteristics of high strength, good stability, and excellent waterproofness; all raw materials used in the present invention are non-toxic and harmless to the environment, and are degradable under the action of microorganisms, giving full play to the concept of green development.

[0018] The present invention prepares a composite copolyester through esterification reaction of adipic acid, (R, S)-1,2,3,4-butanetetrol, terephthalic acid and ethylene glycol, and cooperates with the copolyester through surface modification and coating of a nano-montmorillonite hydrophobic layer, thereby maintaining a certain tensile strength and melt viscosity, and improving its peel strength, boiling water peel strength and bonding strength.

[0019] The present invention ensures the bonding strength by introducing nano-powder montmorillonite to coat the copolyester, and improves the problem of too fast cooling and solidification during melt processing by introducing adipic acid and (R,S)-1,2,3,4-butanetetrol, while improving the boiling water washing resistance of the copolyester hot melt adhesive, which provides a new idea for improving the processing stability of bio-based copolyester, especially in a high humidity environment. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 This is a scanning electron microscope image of the surface of the poplar wood board after the hot melt adhesive was peeled off.

[0021] Figure 2 It is the contact angle of the surface of the hot melt adhesive after self-curing at room temperature. DETAILED DESCRIPTION

[0022] The present invention is further described below in conjunction with specific embodiments.

[0023] Example 1

[0024] 90.12 g of 1,4-butanediol, 51.14 g of adipic acid, 58.04 g of terephthalic acid, and 3.663 g of (R,S)-1,2,3,4-butanetetrol were added to a three-necked flask, and the temperature was raised to 180°C. 2.04 g of tetrabutyl titanate catalyst was slowly dripped into the three-necked flask. The entire experiment was carried out by stirring the three-necked flask at a uniform speed and passing nitrogen protection. The polymerization reaction was carried out for 2.5 hours to obtain an oligomer polyester. 58.04 g of terephthalic acid was added to the three-necked flask containing the oligomer polyester. After reacting for 1 hour, 2.04 g of the catalyst was slowly dripped into the three-necked flask. The polymerization reaction was carried out for 2.5 hours to obtain a low molecular weight mixed polyester. The copolyester and 1.02g of catalyst were added to a nitrogen-protected three-necked flask and stirred. The temperature of the three-necked flask was raised to 228°C, and the polycondensation reaction was carried out for 3.5h. The three-necked flask was evacuated to an internal pressure of less than 300pa, and the reaction was kept warm for 1.5h. The viscous copolyester was cooled to room temperature and filtered and purified in tetrachloroethane to obtain the copolyester. The copolyester was fully blended with 0.25g of montmorillonite and added to the extruder. The temperature of the extruder was raised to 228°C, and the material was pulled out by water cooling. After complete cooling, it was crushed and passed through a 100-mesh screen to obtain the final product, i.e., the target copolyester hot melt adhesive Example 1.

[0025] Example 2

[0026] 90.12 g of 1,4-butanediol, 51.14 g of adipic acid, 58.04 g of terephthalic acid, and 3.663 g of (R,S)-1,2,3,4-butanetetrol were added to a three-necked flask, and the temperature was raised to 180°C. 2.04 g of tetrabutyl titanate catalyst was slowly dripped into the three-necked flask. The entire experiment was carried out by stirring the three-necked flask at a uniform speed and passing nitrogen protection. The polymerization reaction was carried out for 2.5 hours to obtain an oligomer polyester. 58.04 g of terephthalic acid was added to the three-necked flask containing the oligomer polyester. After reacting for 1 hour, 2.04 g of the catalyst was slowly dripped into the three-necked flask. The polymerization reaction was carried out for 2.5 hours to obtain a low molecular weight mixed polyester. The copolyester and 1.02g of catalyst were added to a nitrogen-protected three-necked flask and stirred. The temperature of the three-necked flask was raised to 228°C. The polycondensation reaction was carried out for 3.5h. The three-necked flask was evacuated to an internal pressure of less than 300pa. The reaction was kept warm for 1.5h. The viscous copolyester was cooled to room temperature and filtered and purified in tetrachloroethane to obtain the copolyester. The copolyester was fully blended with 0.5g of montmorillonite and added to the extruder. The temperature of the extruder was raised to 228°C. The material was pulled out by water cooling, completely cooled, crushed, and passed through a 100-mesh sieve to obtain the final product, i.e., the target copolyester hot melt adhesive Example 2.

[0027] Example 3

[0028] 90.12 g of 1,4-butanediol, 51.14 g of adipic acid, 58.04 g of terephthalic acid, and 3.663 g of (R,S)-1,2,3,4-butanetetrol were added to a three-necked flask, and the temperature was raised to 180°C. 2.04 g of tetrabutyl titanate catalyst was slowly dripped into the three-necked flask. The entire experiment was carried out by stirring the three-necked flask at a uniform speed and passing nitrogen protection. The polymerization reaction was carried out for 2.5 hours to obtain an oligomer polyester. 58.04 g of terephthalic acid was added to the three-necked flask containing the oligomer polyester. After reacting for 1 hour, 2.04 g of the catalyst was slowly dripped into the three-necked flask. The polymerization reaction was carried out for 2.5 hours to obtain a low molecular weight mixed polyester. The copolyester and 1.02g of catalyst were added to a nitrogen-protected three-necked flask and stirred. The temperature of the three-necked flask was raised to 228°C. The polycondensation reaction was carried out for 3.5h. The three-necked flask was evacuated to an internal pressure of less than 300pa. The reaction was kept warm for 1.5h. The viscous copolyester was cooled to room temperature and filtered and purified in tetrachloroethane to obtain the copolyester. The copolyester was fully blended with 0.75g of montmorillonite and added to the extruder. The temperature of the extruder was raised to 228°C. The material was pulled out by water cooling, completely cooled, crushed, and passed through a 100-mesh sieve to obtain the final product, i.e., the target copolyester hot melt adhesive Example 3.

[0029] Example 4

[0030] 90.12 g of 1,4-butanediol, 51.14 g of adipic acid, 58.04 g of terephthalic acid, and 3.663 g of (R,S)-1,2,3,4-butanetetrol were added to a three-necked flask, and the temperature was raised to 180°C. 2.04 g of tetrabutyl titanate catalyst was slowly dripped into the three-necked flask. The entire experiment was carried out by stirring the three-necked flask at a uniform speed and passing nitrogen protection. The polymerization reaction was carried out for 2.5 hours to obtain an oligomer polyester. 58.04 g of terephthalic acid was added to the three-necked flask containing the oligomer polyester. After reacting for 1 hour, 2.04 g of the catalyst was slowly dripped into the three-necked flask. The polymerization reaction was carried out for 2.5 hours to obtain a low molecular weight mixed polyester. The copolyester and 1.02g of catalyst were added to a nitrogen-protected three-necked flask and stirred. The temperature of the three-necked flask was raised to 228°C, and the polycondensation reaction was carried out for 3.5h. The three-necked flask was evacuated to an internal pressure of less than 300pa, and the reaction was kept warm for 1.5h. The viscous copolyester was cooled to room temperature and filtered and purified in tetrachloroethane to obtain the copolyester. The copolyester was fully blended with 1g of montmorillonite and added to the extruder. The temperature of the extruder was raised to 228°C, and the material was pulled out by water cooling. After complete cooling, it was crushed and passed through a 100-mesh screen to obtain the final product, namely, the target copolyester hot melt adhesive Example 4.

[0031] Example 5

[0032] 90.12 g of 1,4-butanediol, 51.14 g of adipic acid, 58.04 g of terephthalic acid, and 3.663 g of (R,S)-1,2,3,4-butanetetrol were added to a three-necked flask, and the temperature was raised to 180°C. 2.04 g of tetrabutyl titanate catalyst was slowly dripped into the three-necked flask. The entire experiment was carried out by stirring the three-necked flask at a uniform speed and passing nitrogen protection. The polymerization reaction was carried out for 2.5 hours to obtain an oligomer polyester. 58.04 g of terephthalic acid was added to the three-necked flask containing the oligomer polyester. After reacting for 1 hour, 2.04 g of the catalyst was slowly dripped into the three-necked flask. The polymerization reaction was carried out for 2.5 hours to obtain a low molecular weight mixed polyester. The copolyester and 1.02g of catalyst were added to a nitrogen-protected three-necked flask and stirred. The temperature of the three-necked flask was raised to 228°C. The polycondensation reaction was carried out for 3.5h. The three-necked flask was evacuated to an internal pressure of less than 300pa. The reaction was kept warm for 1.5h. The viscous copolyester was cooled to room temperature and filtered and purified in tetrachloroethane to obtain the copolyester. The copolyester was fully blended with 1.25g of montmorillonite and added to the extruder. The temperature of the extruder was raised to 228°C. The material was pulled out by water cooling, completely cooled, crushed, and passed through a 100-mesh sieve to obtain the final product, i.e., the target copolyester hot melt adhesive Example 5.

[0033] Control group 1

[0034] 90.12 g of 1,4-butanediol, 51.14 g of adipic acid, 58.04 g of terephthalic acid, and 3.663 g of (R,S)-1,2,3,4-butanetetrol were added to a three-necked flask, and the temperature was raised to 180°C. 2.04 g of tetrabutyl titanate catalyst was slowly dripped into the three-necked flask. The entire experiment was carried out by stirring the three-necked flask at a uniform speed and passing nitrogen protection. The polymerization reaction was carried out for 2.5 hours to obtain an oligomer polyester. 58.04 g of terephthalic acid was added to the three-necked flask containing the oligomer polyester. After reacting for 1 hour, 2.04 g of the catalyst was slowly dripped into the three-necked flask. The polymerization reaction was carried out for 2.5 hours to obtain a low molecular weight mixed polyester. The copolyester and 1.02 g of catalyst were added into a three-necked flask protected by nitrogen and stirred. The temperature of the three-necked flask was raised to 228°C and the polycondensation reaction was carried out for 3.5 hours. The three-necked flask was evacuated to an internal pressure of less than 300 Pa and the reaction was kept warm for 1.5 hours. The viscous copolyester was cooled to room temperature and filtered and purified in tetrachloroethane to obtain the copolyester.

[0035] Performance Test:

[0036] Among them, according to "GB / T1040-2006 Determination of tensile properties of plastics", the tensile strength test of Examples 1-3 and Comparative Examples 1-3 was carried out, and the melt viscosity and softening temperature of the hot melt adhesives prepared in Examples 1-3 and Comparative Examples 1-3 were measured according to the standard GB / T16998-1997 "Determination of thermal stability of hot-melt adhesives", and the hot melt adhesives prepared in Examples 1-3 and Comparative Examples 1-3 were heated and melted using a hot melt device, and then evenly coated on the surface of transparent glass, and the transparent glass coated with the hot melt adhesive was placed in a room temperature environment with a humidity of 45% for curing and curing for 10 hours, forming a glue layer with a thickness of 0.2±0.02 mm on the glass surface, and the 180° peel strength of the glue layer was measured according to the standard GB / T2790-1995 "Adhesive 180° Peel Strength Test Method Flexible Material to Rigid Material", and the peel strength test standard is: GB / T11402-1989. Hydrolysis resistance test of hot melt adhesive products: dumbbell-shaped adhesive samples (consistent with tensile strength samples) are made, and the initial tensile strength is compared with the tensile strength of the adhesive sample after boiling in boiling water for 30 minutes and kept at 25°C for 2 months. Adhesion strength test: The adhesion performance of hot melt adhesive is tested in accordance with GB / T5210-2006 "Adhesion test of paint and varnish by pull-off method".

[0037] The relevant performance test results of the obtained samples are shown in the following table:

[0038] Table 1 Tensile strength and melt viscosity test results

[0039]

[0040] Table 2 Softening temperature measurement results

[0041]

[0042] Comparing and analyzing the data in the above table, the melt viscosity of the hot melt adhesive prepared in Example 3 of the present invention reaches 5100mPa / s, the softening temperature reaches 137°C, the 180° peel strength reaches 28.23N / 15mm, and the bonding strength reaches 10.25MPa. After being fully soaked in boiling water for 30min, the 180° peel strength remains at 23.12N / 15mm, the peel strength loss is 14.34%, and the bonding strength remains at 8.77MPa. The comprehensive test data of Example 3 show that The results are better than the comprehensive detection data structure of the control example, indicating that the present invention prepares a bio-based degradable boiling water resistant hot melt adhesive copolyester material suitable for the surface bonding of poplar wood boards, and the raw materials are esterified by adipic acid, (R, S)-1,2,3,4-butanetetrol with terephthalic acid and 1,4-butanediol to prepare a composite copolyester, and the surface is modified and coated with a nano-montmorillonite hydrophobic layer to cooperate with the copolyester, thereby maintaining a certain tensile strength and melt viscosity, and improving its peel strength, boiling water peel strength and bonding strength.

[0043] It can be seen that the present invention ensures the bonding strength by introducing nano-powders to coat the copolyester, and improves the problem of too fast cooling and solidification during melt processing by introducing adipic acid and (R,S)-1,2,3,4-butanetetrol, while improving the boiling water washing resistance of the copolyester hot melt adhesive. This provides a new idea for improving the processing stability of bio-based copolyesters, especially in high humidity environments.

Claims

1. A degradable boiling water resistant hot melt adhesive copolyester material, characterized in that: The invention is prepared from the following raw materials in the following molar proportions: 1 part of 1,4-butanediol, 0.35 parts of adipic acid, 0.35 parts of terephthalic acid, 0.03 parts of (R,S)-1,2,3,4-butanetetrol, 0.012 parts of tetrabutyl titanate, and 0.001 to 0.005 parts of montmorillonite.

2. The method for preparing a degradable boiling water resistant hot melt adhesive copolyester material according to claim 1, characterized in that: The following steps are involved: A1. Add 1,4-butanediol, adipic acid and (R,S)-1,2,3,4-butanetetrol in a molar distribution ratio into a three-necked flask in sequence and heat to raise the temperature. Add tetrabutyl titanate as a catalyst dropwise into the three-necked flask, stir at a uniform speed and introduce nitrogen for protection. The polymerization reaction is carried out for 2-3 hours to obtain an oligomer polyester. A2. Add terephthalic acid to a three-necked flask containing oligomer polyester, react for 1 hour, then drop tetrabutyl titanate as a catalyst, and polymerize for 2-3 hours to obtain a low molecular weight mixed polyester; A3, adding low molecular weight mixed polyester and catalyst tetrabutyl titanate into a three-necked flask protected by nitrogen and stirring, heating the three-necked flask to raise the temperature, polycondensation reaction for 3-4 hours, evacuating the three-necked flask until the internal pressure is lower than 300 Pa, keeping the temperature for reaction for 1-2 hours, reducing the viscous copolyester to room temperature, filtering and purifying in tetrachloroethane to obtain the copolyester; A4. The copolyester and nano-montmorillonite are fully blended and added into the extruder. The temperature of the extruder is increased to 225-230°C. The material is discharged through water cooling and traction. After being completely cooled, it is crushed and passed through a 100-mesh sieve to obtain the final product, a degradable boiling water-resistant hot melt adhesive copolyester material.

3. The method for preparing a degradable boiling water resistant hot melt adhesive copolyester material according to claim 2, characterized in that: In step A1, the temperature is raised to 170-190° C. to carry out polymerization reaction.

4. The method for preparing a degradable boiling water resistant hot melt adhesive copolyester material according to claim 2, characterized in that: In step A3, the temperature is raised to 225-230° C. to carry out polycondensation reaction.

5. The method for preparing a degradable boiling water resistant hot melt adhesive copolyester material according to claim 2, characterized in that: The molar ratio of tetrabutyl titanate as the catalyst added in steps A1, A2 and A3 is 2:2:

1.

6. Use of the degradable boiling water resistant hot melt adhesive copolyester material as claimed in claim 1 in bonding the surface of poplar wood boards.

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