CN-121975479-A - High-transparency TPU hot melt adhesive film composition and production process thereof

Abstract

The invention discloses a high-transparency TPU hot melt adhesive film composition and a production process thereof, and belongs to the technical field of high polymer materials. The composition comprises a TPU matrix, a high polymer modifier and the like, and the production process comprises the steps of synthesis of a four-arm star-shaped high polymer modifier, vacuum dehydration of raw materials, high-speed mixing, gradient temperature control extrusion granulation, gradient melting-rapid cooling casting film formation under nitrogen protection. The invention provides a star topology modifier design and double covalent crosslinking synergistic scheme for solving the defects of insufficient transparency, poor bonding durability and easy migration of a modifier of the conventional TPU hot melt adhesive film, realizes molecular-level compatibility of the modifier and the TPU, finally obtains the hot melt adhesive film with high transparency, high bonding stability and excellent processing performance, and is suitable for high-end scenes such as optical device bonding.

Inventors

• ZHANG JINCONG
• CHEN SHAOPING
• WU YIJIAO
• Sun Yuankang
• ZHU QINGHUA

Assignees

• 华世（福建)科技有限公司

Dates

Publication Date

20260505

Application Date

20260408

Claims (5)

1. 1. The high-transparency TPU hot melt adhesive film composition is characterized by comprising the following components in parts by weight: 60-85 parts of TPU matrix; 5-20 parts of a high molecular modifier; 0.5-2 parts of antioxidant; 0.3-1.5 parts of reactive ultraviolet absorber; 3-10 parts of transparent tackifier; The TPU matrix is aliphatic polybutylene adipate type TPU with the Shore hardness of 85-95A, the number average molecular weight of 30000-80000 and the soft segment content of 40-60 percent; The macromolecular modifier is pentaerythritol-initiated polycaprolactone-polyethylene glycol-primary amino-containing acrylamide copolymer chain segment grafted maleic anhydride, the number average molecular weight of the macromolecular modifier is 10000-30000, the grafting rate of the maleic anhydride is 3.5-6.5%, the proportion of the primary amino-containing chain segment is 5-15%, the maleic anhydride group and the TPU terminal amino form amide bond crosslinking, and the amino group containing the primary amino chain segment and the carboxyl formed after the opening of the maleic anhydride form auxiliary crosslinking; the reaction type ultraviolet absorbent is 2-hydroxy-4- (2-hydroxyethyl) oxybenzophenone; The transparent tackifier is hydrogenated rosin glyceride, and the refractive index difference between the hydrogenated rosin glyceride and the refractive indexes of the TPU matrix and the macromolecular modifier is less than or equal to 0.005.
2. 2. The high-transparency TPU hot melt adhesive film composition according to claim 1, wherein the antioxidant is a compound system of hindered phenol antioxidants and phosphite antioxidants, and the mass ratio is 1:1-2:1.
3. 3. The high-transparency TPU hot melt adhesive film composition according to claim 1, wherein the high-molecular modifier is prepared by adopting a modularized step-by-step synthesis and in-situ grafting process, and specifically comprises the following steps: s1, synthesizing a polycaprolactone core: adding pentaerythritol, epsilon-caprolactone and stannous octoate with the mass ratio of 1:40:0.002 into a reaction kettle, reacting for 6 hours at 125 ℃ under the protection of nitrogen, washing and drying to obtain a polycaprolactone star-shaped core; s2, preparing star-type polycaprolactone-polyethylene glycol: Adding a polycaprolactone core, ethylene oxide and stannous octoate in a mass ratio of 1:1:0.001 into a reaction kettle, reacting for 7 hours at 140 ℃ under the protection of nitrogen and under the pressure of 0.8-1.5MPa in the autoclave, and obtaining star-shaped polycaprolactone-polyethylene glycol through precipitation, washing and drying; s3, double bond functionalization modification: Adding star polycaprolactone-polyethylene glycol, glycidyl methacrylate and triethylamine with the mass ratio of 3:1:0.003 into a reaction kettle, reacting for 4-6 hours at 110-120 ℃, and purifying to obtain double bond functionalized star copolymer; S4, in-situ grafting maleic anhydride: Adding a double bond functionalized star copolymer, N-acryloyloxy succinimide and an initiator azodiisobutyronitrile into toluene, reacting for 7 hours at 75 ℃ under the protection of nitrogen, cooling to 55 ℃, adding ethylenediamine for reacting for 2 hours, heating to 155 ℃ for reacting for 3.5 hours, dropwise adding maleic anhydride accounting for 18 percent of the total mass of the system and dicumyl peroxide accounting for 0.5 percent of the mass of the maleic anhydride, and finally precipitating, washing, drying and granulating to obtain the polymer modifier.
4. 4. A process for the production of a high transparency TPU hot melt adhesive film composition according to any one of claims 1 to 3 comprising the steps of: s1, pretreatment of raw materials: vacuum drying TPU matrix, polymer modifier and transparent tackifier at 80-100deg.C for 4-6 hr; S2, mixing ingredients: Weighing the components according to the parts by weight, putting the components into a high-speed mixer, and mixing for 5-10min at the rotating speed of 300-500r/min to obtain a mixed material; S3, extrusion granulation: Adding the mixed materials into a double-screw extruder, wherein the temperatures of all sections of the extruder are 140-160 ℃ in a feeding section, 170-190 ℃ in a compression section, 180-200 ℃ in a homogenizing section, 190-210 ℃ in a machine head, and the rotating speed of the screw is 150-250r/min, and performing water cooling and granulating after extrusion to obtain hot melt adhesive particles; S4, casting film formation: and adding the hot melt adhesive particles into a casting film machine, casting at a temperature of 180-200 ℃ for a charging barrel of the casting machine, 190-210 ℃ for a die head, 20-40 ℃ for a casting roller, casting and forming under the protection of nitrogen, and drawing and rolling to obtain the high-transparency TPU hot melt adhesive film with the thickness of 0.05-0.5 mm.
5. 5. The process for producing a high transparency TPU hot melt adhesive film composition according to claim 4, wherein the cooling temperature in casting is 30 ℃.

Description

High-transparency TPU hot melt adhesive film composition and production process thereof Technical Field The invention relates to the technical field of high polymer materials, in particular to a high-transparency TPU hot melt adhesive film composition and a production process thereof. Background The hot melt adhesive film has the advantages of environmental protection, no solvent, high bonding efficiency, convenient construction and the like, and is widely applied to the fields of optical device bonding, electronic element packaging, automobile interior bonding and the like. The Thermoplastic Polyurethane (TPU) hot melt adhesive film is a preferable material for high-end application scenes by virtue of excellent flexibility and low temperature resistance, but in practical application, the Thermoplastic Polyurethane (TPU) hot melt adhesive film needs to meet core requirements of high transparency, high bonding stability and excellent ageing resistance, and the existing product generally has the technical problems of insufficient transparency, poor bonding durability, easy occurrence of energy attenuation after long-term use and the like. In order to improve the performance defects, the prior art mainly adopts two solutions, namely, the film forming quality is improved by optimizing processing technological parameters, such as adjusting extrusion temperature, casting speed and the like, and the compatibility and the bonding performance are regulated and controlled by adding a plasticizer, a tackifier, an inorganic nano filler or a common linear modifier into a TPU matrix. However, the existing solution still has obvious defects that the process optimization can only improve the surface forming effect and can not fundamentally solve the problem of poor molecular-level compatibility of materials, inorganic fillers are easy to cause phase separation to increase haze and destroy transparency, common modifiers are mostly physically blended and are combined with a TPU matrix only by intermolecular force and are easy to migrate and separate out after long-term use to cause the attenuation of bonding strength, and the existing modifiers have single function and are difficult to simultaneously consider transparency, bonding stability and aging resistance. Therefore, a modification system which can realize molecular-level compatibility, form stable chemical connection with TPU and has multiple functions is developed, becomes a key for solving the problem of the short-term performance plate of the conventional TPU hot melt adhesive film, and is a technical bottleneck to be broken through in the field. Disclosure of Invention The invention aims to solve the defects in the prior art, and provides a high-transparency TPU hot melt adhesive film composition and a production process thereof. In order to achieve the above purpose, the present invention adopts the following technical scheme: a production process of a high-transparency TPU hot melt adhesive film composition comprises the following steps: s1, synthesizing a high-molecular modifier: adding pentaerythritol, epsilon-caprolactone and stannous octoate with the mass ratio of 1:40:0.002 into a reaction kettle, reacting for 6 hours at 125 ℃ under the protection of nitrogen, washing and drying to obtain a polycaprolactone star-shaped core; The method comprises the steps of respectively initiating 4 hydroxyl groups of pentaerythritol as initiation sites to carry out ring-opening polymerization of epsilon-caprolactone, wherein the polymerization degree of each branched chain is n, the product is of a symmetrical four-arm star structure, and the mechanism core of the reaction is coordination-insertion ring-opening polymerization, wherein Sn 4+ in stannous octoate and the hydroxyl groups of pentaerythritol form an Sn-O coordination intermediate to activate the nucleophilic activity of hydroxyl groups, then, the carbonyl groups of epsilon-caprolactone molecules and Sn 4+ generate electrophilic interaction to enable the polarization cleavage of lactone ring C-O bonds to complete ring opening, then, the activated hydroxyl oxygen attacks positively charged carbonyl carbon of ring-opening lactone to insert monomers between Sn-O bonds to realize chain growth, and finally, the chain termination is completed through proton transfer to ensure that the branching degree of the product is stable to be 4 and no obvious side reaction is generated; The core is used as a basic skeleton of the modifier, and the core functions are characterized in that 4 accurate reaction sites are provided for grafting of subsequent PEG, primary amino-containing chain segments and maleic anhydride, the design of the modifier with single molecule integrated multiple functions is guaranteed, the PCL chain segments are similar to the aliphatic polyester hard segment structure of the TPU matrix, molecular-level compatibility can be realized through crystallization synergism, the problem of phase separation is fun