High-elasticity hot-melt spandex glue and preparation method thereof

Abstract

The invention relates to the technical field of adhesives, and discloses a high-elasticity hot-melt spandex adhesive and a preparation method thereof.The high-elasticity hot-melt spandex adhesive comprises a spandex layer and hot-melt adhesive layers arranged on the two sides of the spandex layer, a chain extender with a special structure is prepared and participates in chain extension polymerization of the polyurethane filaments, the chain extender can reduce interaction force between molecular chains of the polyurethane filaments and reduce formation of crystalline regions of hard segments, the existence of a methyl side chain can greatly reduce the reaction activity of secondary amino groups, the internal stress of the polyurethane filaments is reduced, the elasticity of the polyurethane filaments is effectively enhanced, and the service life of the polyurethane filaments is prolonged. The rigid spiral ring in the chain extender structure can improve the mechanical strength of the spandex. Spandex grey cloth formed by weft knitting of spandex filaments is used as a spandex core layer of the hot melt adhesive, thin TPU hot melt adhesive is thermally attached to the two sides of the spandex layer, and the hot melt spandex adhesive with the high-elasticity effect is prepared.

Description

Technical Field

[0001] The present invention relates to the technical field of adhesives, and particularly relates to a highly elastic hot-melt spandex adhesive and a preparation method thereof. Background Art

[0002] Today, in the pursuit of fashion and comfort, seamless clothing has won the favor of consumers with its high fitting degree, flat appearance, and comfortable wearing experience, and has gradually become the darling of the market. The core of seamless clothing lies in its "seamless" feature, which means that no obvious stitches or splicing marks should be left when the clothing is spliced and fixed. Traditional sewing techniques, although able to meet the basic clothing production requirements, are inadequate in the production of seamless clothing. Needles and stitches not only damage the overall aesthetic of the clothing but also may affect the wearing comfort. Therefore, seamless clothing requires a more advanced fixing technology, and hot-melt adhesives are the ideal choice to meet this need.

[0003] Hot-melt adhesives have excellent adhesiveness and softness, and can quickly melt and bond fabrics at high temperatures to form a seamless connection. In the production process of seamless clothing, dotting technology or adhesive application processes are usually adopted to splice different parts of the fabric through double-sided hot-melt adhesives or hot-melt adhesive films. This splicing method not only has a flat appearance but also is firm and durable, effectively avoiding problems such as thread breakage and thread loosening that may occur in traditional sewing techniques.

[0004] However, due to the high fitting degree of seamless clothing, it needs to meet the high elasticity required for frequent stretching movements during wearing. Although traditional hot-melt adhesives such as TPU have a certain degree of elasticity, the adhesive film is prone to losing elasticity and even experiencing adhesive failure during such continuous stretching processes, which greatly shortens the service life of seamless clothing. Based on this, developing a type of highly elastic hot-melt adhesive is of great significance for the further development of seamless clothing. Summary of the Invention

[0005] In order to solve the problems mentioned in the background art, the purpose of the present invention is to provide a highly elastic hot-melt spandex adhesive and a preparation method thereof.

[0006] The purpose of the present invention can be achieved through the following technical solutions:

[0007] A preparation method of a highly elastic hot-melt spandex adhesive, the hot-melt spandex adhesive comprising a spandex layer and hot-melt adhesive layers disposed on both sides of the spandex layer; the spandex layer is prepared by performing weft knitting on spandex filaments;

[0008] The spandex filaments are made from raw materials including the following parts by weight:

[0009] Polymeric diol 45 - 55 parts;

[0010] 20 - 30 parts of isocyanate monomer;

[0011] 1 - 3 parts of chain extender;

[0012] The preparation method of the hot - melt spandex adhesive comprises the following steps:

[0013] First step, perform weft knitting on spandex filaments to make a greige fabric, conduct high - temperature setting at 180 - 200 °C, then cut the greige fabric into long strips, and through the edge - trimming process, form a spandex layer;

[0014] Second step, thermally bond the TPU hot - melt adhesive film on both sides of the spandex layer to obtain the hot - melt spandex adhesive.

[0015] As a further scheme of the present invention, the specific preparation method of the spandex filaments comprises the following steps:

[0016] Step 1, by weight, vacuum - dry and dehydrate the polyol, then add it to N,N - dimethylacetamide, stir and mix evenly, continue to add the isocyanate monomer, after adding, raise the temperature to 80 - 100 °C, and stir and polymerize for 1 - 3 h to form a prepolymer mixture;

[0017] Step 2, lower the temperature to 10 - 30 °C, under stirring conditions, add the chain extender to the prepolymer mixture, then raise the temperature to 70 - 80 °C, stir and chain - extend for 6 - 12 h, then stop heating, cool down and discharge to form a spandex spinning solution;

[0018] Step 3, perform dry spinning on the spandex spinning solution to obtain spandex filaments.

[0019] As a further scheme of the present invention, the polyol is at least one of polypropylene glycol or polytetramethylene ether glycol.

[0020] As a further scheme of the present invention, the isocyanate monomer is at least one of isophorone diisocyanate, hexamethylene diisocyanate, 4,4 - diphenylmethane diisocyanate or 2,2 - diphenylmethane diisocyanate.

[0021] As a further scheme of the present invention, the specific preparation method of the chain extender is as follows:

[0022] Introduce high - purity nitrogen into the reaction kettle to discharge air, then add spirobisphenol and toluene to the reaction kettle, start stirring, add an aqueous solution of alkaline hydroxide, after mixing evenly, add 2 - chloro - N - methylethylamine hydrochloride to the reaction kettle, start heating, maintain the temperature in the reaction kettle at 60 - 70 °C, keep stirring for 4 - 6 h, then stop heating, adjust the pH to 6 - 7, filter out the solid product by reduced - pressure filtration, and then through the purification and post - treatment process, the chain extender can be obtained.

[0023] As a further solution of the present invention, the alkaline hydroxide is sodium hydroxide or potassium hydroxide.

[0024] As a further solution of the present invention, the mass fraction of the aqueous solution of the alkaline hydroxide is 20-30%.

[0025] As a further solution of the present invention, the molar ratio of the spirobiphenol to 2-chloro-N-methyl ethylamine hydrochloride is 1:2.

[0026] As a further solution of the present invention, the temperature of the thermal lamination is 100-120 °C.

[0027] A highly elastic hot-melt polyurethane elastic fiber adhesive is prepared by the above preparation method.

[0028] Advantages of the present invention:

[0029] In the present invention, a chain extender with a special structure is prepared and participates in the chain extension polymerization of polyurethane filaments. Compared with the traditional diamine chain extender, on the one hand, the chain extender prepared in the present invention has a methyl side chain. The existence of this side chain structure can reduce the intermolecular interaction force between the polyurethane molecular chains, thereby reducing the formation of the crystalline region of the hard segment. Moreover, the existence of the methyl side chain will greatly reduce the reaction activity of the secondary amino group, thereby reducing the generation of cross-linking reactions and reducing internal stress. In addition, the chain extender of the present invention is not a straight-chain structure. Therefore, during the chain extension polymerization process, the regularity of the polyurethane molecular chain will be greatly reduced, which can also play a role in reducing the internal stress of the polyurethane elastic fiber, thereby effectively enhancing the elasticity of the polyurethane elastic fiber. In addition, the chain extender contains a rigid spiro ring, which can make the polyurethane elastic fiber more rigid, thereby compensating for the loss of mechanical strength caused by the reduction of internal stress and achieving a dynamic balance effect, so that the prepared polyurethane elastic fiber not only has a high-elasticity effect but also has good mechanical strength.

[0030] In the present invention, the polyurethane elastic fiber fabric formed by weft knitting of polyurethane elastic fiber is used as the polyurethane elastic fiber core layer of the hot-melt adhesive, and a thin TPU hot-melt adhesive film is thermally laminated on both sides of the polyurethane elastic fiber layer to form a hot-melt polyurethane elastic fiber adhesive. Utilizing the high-elasticity effect of the polyurethane elastic fiber, the hot-melt polyurethane elastic fiber adhesive can still maintain a good bonding effect during high-frequency stretching processes, and can meet the usage requirements of seamless clothing.

[0031] Of course, it is not necessary for any product implementing the present invention to simultaneously achieve all the above-mentioned advantages. Description of the Drawings

[0032] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for describing the embodiments will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0033] Figure 1 Infrared test chart of the chain extender;

[0034] Figure 2 Schematic structural diagram of the hot-melt spandex adhesive, where (1) and (3) are hot-melt adhesive layers, and (2) is a spandex layer. Specific implementation manners

[0035] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative efforts belong to the scope of protection of the present invention.

[0036] Example 1

[0037] Preparation of spandex filaments:

[0038] Step 1: According to parts by weight, 45 parts of polyol are vacuum-dried and dehydrated, and then added to N,N-dimethylacetamide, stirred and mixed evenly. Then, 20 parts of 4,4-diphenylmethane diisocyanate are added. After adding, the temperature is raised to 80 °C, and stirring and polymerization are carried out for 3 h to form a prepolymer mixture.

[0039] Step 2: Lower the temperature to 20 °C. Under stirring conditions, 1 part of the chain extender is added to the prepolymer mixture, and then the temperature is raised to 70 °C. After stirring and chain extending for 12 h, heating is stopped, and the temperature is lowered and discharged to form a spandex spinning solution.

[0040] Step 3: Extrude the spandex spinning solution through a spinneret in a duct for dry spinning to obtain spandex filaments.

[0041] Among them, the polyol is polytetramethylene ether glycol with a number average molecular weight of 2000, and the same applies hereinafter.

[0042] Example 2

[0043] Preparation of spandex filaments:

[0044] Step 1: According to parts by weight, 48 parts of polyol are vacuum-dried and dehydrated, and then added to N,N-dimethylacetamide, stirred and mixed evenly. Then, 25 parts of 2,2-diphenylmethane diisocyanate are added. After adding, the temperature is raised to 90 °C, and stirring and polymerization are carried out for 2 h to form a prepolymer mixture.

[0045] Step 2: Lower the temperature to 20 °C. Under stirring conditions, 2.5 parts of the chain extender are added to the prepolymer mixture, and then the temperature is raised to 75 °C. After stirring and chain extending for 9 h, heating is stopped, and the temperature is lowered and discharged to form a spandex spinning solution.

[0046] Step 3: Extrude the spandex spinning solution through a spinneret in a duct for dry spinning to obtain spandex filaments.

[0047] Example 3

[0048] Preparation of spandex filaments:

[0049] Step 1: By weight, vacuum dry and dehydrate 55 parts of polyol, then add it to N,N-dimethylacetamide, stir and mix evenly. Then add 30 parts of 2,2-diphenylmethane diisocyanate. After adding, raise the temperature to 100 °C and stir and polymerize for 1 h to form a prepolymer mixture.

[0050] Step 2: Lower the temperature to 20 °C. Under stirring conditions, add 3 parts of chain extender to the prepolymer mixture, then raise the temperature to 80 °C, stir and chain extend for 6 h, stop heating, cool down and discharge to form a spandex spinning solution.

[0051] Step 3: Extrude the spandex spinning solution through a spinneret in a duct for dry spinning to obtain spandex filaments.

[0052] The chain extender in the above examples is prepared by the following method:

[0053] Introduce high-purity nitrogen into the reaction kettle to discharge air. Then add 0.4 g of spirobiphenol and toluene to the reaction kettle, start stirring, add 2 mL of 20% by mass aqueous sodium hydroxide solution, mix evenly, and then add 0.41 g of 2-chloro-N-methylethylamine hydrochloride to the reaction kettle. Start heating and maintain the temperature in the reaction kettle at 65 °C. After heat preservation and stirring for 6 h, stop heating, adjust the pH to 7, filter out the solid product by vacuum filtration, and then through the purification and post-treatment process, the chain extender can be obtained.

[0054] Figure 1 This is the infrared test chart of the chain extender. The characteristic absorption peak appearing at 3303 cm -1 is attributed to the characteristic absorption peak of secondary amine N-H. The characteristic absorption peaks appearing at 3000 cm -1 -3100 cm -1 are attributed to the C-H characteristic absorption peak of the benzene ring skeleton in the spiro structure. The characteristic absorption peak appearing at 1060 cm -1 is attributed to the C-O characteristic absorption peak of the ether bond. Obviously, this ether bond is formed by the substitution reaction of the phenolic hydroxyl group in the spirobiphenol structure with the halogen substituent in the 2-chloro-N-methylethylamine hydrochloride structure under the catalytic action of sodium hydroxide.

[0055] Comparative Example 1

[0056] Preparation of spandex filaments:

[0057] Step 1: Weigh 48 parts by weight of polyol, vacuum dry and dehydrate it, then add it to N,N-dimethylacetamide, stir and mix evenly. Then add 25 parts of 2,2-diphenylmethane diisocyanate. After adding, raise the temperature to 90 °C and stir and polymerize for 2 h to form a prepolymer mixture.

[0058] Step 2: Lower the temperature to 20 °C. Under stirring conditions, add 2.5 parts of chain extender ethylenediamine to the prepolymer mixture. Then raise the temperature to 75 °C and stir for chain extension for 9 h. After that, stop heating and cool down to discharge to form a polyurethane fiber spinning solution.

[0059] Step 3: Extrude the polyurethane fiber spinning solution through a spinneret into a duct for dry spinning to obtain polyurethane fibers.

[0060] Test Example

[0061] According to the standard FZ / T 54010-2014, various performance tests were carried out on the polyurethane fibers in the examples and comparative examples, and the results are recorded in Table 1:

[0062] Table 1 - Test Results

[0063] Breaking strength (cN / dtex) 300% Rebound rate (%) Example 1 2.1 96 Example 2 2.2 96 Example 3 2.1 95 Comparative Example 1 2.1 83

[0064] Analysis shows that the polyurethane fibers prepared by chain extension polymerization using the chain extender of the present invention have good mechanical strength and excellent elasticity, achieving a balance between mechanical strength and elasticity, meeting the usage requirements of seamless clothing.

[0065] The high-elastic hot-melt polyurethane adhesive is prepared by using the polyurethane fibers in the examples of the present invention. The specific method is as follows:

[0066] First step: Perform weft knitting process on the polyurethane fibers to make a greige fabric, subject it to high-temperature setting at 200 °C, then cut the greige fabric into long strips and perform trimming process to form a polyurethane layer.

[0067] Second step: Control the temperature at 120 °C and thermally bond the TPU hot-melt adhesive film on both sides of the polyurethane layer to obtain the hot-melt polyurethane adhesive.

[0068] Figure 2 Figure [ID] is a schematic structural diagram of the hot-melt polyurethane adhesive, where (1) and (3) are hot-melt adhesive layers, and (2) is the polyurethane layer.

[0069] In this article, specific examples are used to illustrate the principles and implementation manners of the present invention. The descriptions of the above embodiments are only for helping to understand the method of the present invention and its core ideas, including the best mode, and also enable any person skilled in the art to practice the present invention, including manufacturing and using any device or system, and implementing any combined method. It should be noted that for those of ordinary skill in the art in the technical field, without departing from the principle of the present invention, several improvements and modifications can be made to the present invention, and these improvements and modifications also fall within the protection scope of the claims of the present invention. The protection scope of the present invention patent is defined by the claims and may include other embodiments that can be conceived by those skilled in the art. If these other embodiments have structural elements similar to the literal description of the claims, or if they include equivalent structural elements that have no substantial difference from the literal description of the claims, then these other embodiments should also be included within the scope of the claims.

[0070] The above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions recorded in the foregoing embodiments or perform equivalent replacements for some of the technical features; and these modifications or replacements will not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the various embodiments of the present invention.

Claims

1. A preparation method of a highly elastic hot-melt spandex glue, characterized in that, The hot-melt spandex adhesive comprises a spandex layer and hot-melt adhesive layers arranged on both sides of the spandex layer; the spandex layer is obtained by performing weft knitting on spandex filaments; The spandex filaments are made of raw materials including the following parts by weight: 45-55 parts of polyol; 20-30 parts of isocyanate monomer; 1-3 parts of chain extender; The preparation method of the hot-melt spandex adhesive comprises the following steps: First step, perform weft knitting on spandex filaments to make a greige fabric, perform high-temperature setting at 180-200 °C, then cut the greige fabric into long strips, and form a spandex layer through a trimming process; Second step, thermally bond TPU hot-melt adhesive films on both sides of the spandex layer to obtain the hot-melt spandex adhesive.

2. The preparation method of a highly elastic hot-melt spandex adhesive according to claim 1, characterized in that, The specific preparation method of the spandex filaments comprises the following steps: Step 1, according to the parts by weight, vacuum-dry and dehydrate polyol, then add it to N,N-dimethylacetamide, stir and mix evenly, continue to add the isocyanate monomer, after adding, raise the temperature to 80-100 °C, and stir and polymerize for 1-3 h to form a prepolymer mixture; Step 2, lower the temperature to 10-30 °C, under stirring conditions, add the chain extender to the prepolymer mixture, then raise the temperature to 70-80 °C, stir and chain-extend for 6-12 h, then stop heating, cool down and discharge to form a spandex spinning solution; Step 3, perform dry spinning on the spandex spinning solution to obtain spandex filaments.

3. The preparation method of a highly elastic hot-melt spandex adhesive according to claim 1, characterized in that, The polyol is at least one of polypropylene glycol or polytetramethylene ether glycol.

4. The preparation method of a highly elastic hot-melt spandex adhesive according to claim 1, characterized in that, The isocyanate monomer is at least one of isophorone diisocyanate, hexamethylene diisocyanate, 4,4-diphenylmethane diisocyanate or 2,2-diphenylmethane diisocyanate.

5. The preparation method of a highly elastic hot-melt spandex adhesive according to claim 1, characterized in that, The specific preparation method of the chain extender is as follows: Introduce high-purity nitrogen into the reaction kettle to discharge air, then add spirobisphenol and toluene into the reaction kettle, start stirring, add an aqueous solution of alkaline hydroxide, mix evenly, then add 2-chloro-N-methylethylamine hydrochloride into the reaction kettle, start heating, maintain the temperature in the reaction kettle at 60-70 °C, keep stirring for 4-6 h, then stop heating, adjust the pH to 6-7, filter out the solid product by reduced-pressure filtration, and then perform a purification post-treatment process to obtain the chain extender.

6. The preparation method of a highly elastic hot-melt spandex adhesive according to claim 5, characterized in that, The alkaline hydroxide is sodium hydroxide or potassium hydroxide.

7. The preparation method of a highly elastic hot-melt polyurethane elastomer adhesive according to claim 5, characterized in that, The mass fraction of the aqueous solution of alkaline hydroxide is 20-30%.

8. The preparation method of a highly elastic hot-melt spandex adhesive according to claim 5, characterized in that The molar ratio of the spirobisphenol to 2-chloro-N-methylethylamine hydrochloride is 1:

2.

9. The preparation method of a highly elastic hot-melt spandex adhesive according to claim 1, characterized in that, The temperature of the thermal bonding is 100-120 °C.

10. A highly elastic hot-melt spandex adhesive, characterized in that, It is prepared by using the preparation method described in any one of claims 1-9.

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