CN110128989B

CN110128989B - Polyurethane reworking adhesive and preparation method thereof

Info

Publication number: CN110128989B
Application number: CN201910393261.7A
Authority: CN
Inventors: 黄雪冰; 柯明新
Original assignee: Jiangsu Csi Material Technology Co ltd
Current assignee: Jiangsu Silicon Age Material Technology Co., Ltd.
Priority date: 2019-05-10
Filing date: 2019-05-10
Publication date: 2021-06-22
Anticipated expiration: 2039-05-10
Also published as: CN110128989A

Abstract

The invention discloses a polyurethane reworking adhesive and a preparation method thereof, wherein the polyurethane reworking adhesive mainly comprises 100 parts of silanized polyurethane prepolymer, 10-26 parts of filler, 3-4.5 parts of cross-linking agent, 0.2-0.35 part of catalyst and 0.01-0.08 part of water removing agent. The main chain of the polyurethane reworking adhesive is of a polyurethane structure, the end group is a polyalkoxy group, the polyurethane reworking adhesive has high tensile strength, excellent elasticity, a room-temperature curing mechanism and good bonding strength, has good bonding property to LOCA residual adhesive, is rapidly cured at room temperature, can rapidly remove the LOCA residual adhesive on the surface of a reworked touch screen, and improves the reworking yield of the touch screen.

Description

Polyurethane reworking adhesive and preparation method thereof

Technical Field

The invention relates to the technical field of rework of touch screens, in particular to polyurethane rework glue and a preparation method thereof.

Background

With the rapid development of the electronic information industry and communication technology, electronic touch screens are more and more widely applied to the production and life of people. The touch screen is composed of an inner structure and an outer structure, wherein the inner structure and the outer structure are respectively a display screen, a touch screen and a protection panel, and the display screen, the touch screen and the protection panel are bonded and attached by liquid optical cement. Because the surface tension of the three materials is different, bubbles, foreign matters or offset phenomena often occur in the attaching process, so that the product is poor and needs to be reworked. In the rework treatment process, stripping each component and removing the LOCA residual glue are important, wherein the LOCA residual glue mainly comprises organic silicon, acrylate and polyurethane. There are very few reports in the literature on the removal of LOCA cull.

Disclosure of Invention

The invention aims to overcome the defects in the prior art and provide polyurethane reworking glue for removing LOCA (LOCA-like epoxy adhesive) residual glue and a preparation method thereof.

In order to achieve the purpose, the technical scheme adopted by the invention is that the polyurethane reworking glue comprises a silanized polyurethane prepolymer.

As a preferred embodiment of the polyurethane rework glue of the invention, the polyurethane rework glue further comprises a filler, a cross-linking agent, a catalyst and a water removal agent.

The room temperature cured polyurethane reworked adhesive realizes the adhesive performance by utilizing a three-dimensional network structure produced by hydrolysis and crosslinking of a silanized polyurethane prepolymer. The curing crosslinking structure system is composed of two bonds and chains (namely Si-O-Si bonds and polyurethane chains) with different chemical structures, so that the system is endowed with excellent tensile strength, excellent elasticity and tear strength, Si-OH generated after hydrolysis of Si-OR of a terminal group is easy to react with organic silicon, acrylate and polyurethane in LOCA optical residual glue to form effective bonding, the LOCA residual glue can be removed under the condition of not causing new residues, the curing mechanism is moisture curing, the defect of touch screen damage caused by overhigh rework temperature can be avoided, and the rework yield is improved.

As a preferred embodiment of the polyurethane heavy industry adhesive, the components are calculated according to the following parts by weight: 100 parts of silanized polyurethane prepolymer, 10-26 parts of filler, 3-4.5 parts of cross-linking agent, 0.2-0.35 part of catalyst and 0.01-0.08 part of water removing agent.

Through a large amount of experimental researches, the inventor of the application finds that when the components of the polyurethane reworking glue are selected according to the weight proportion, the polyurethane reworking glue has excellent tensile strength and tearing strength, high hardness and good bonding strength, and can remove LOCA adhesive residue by more than 96%.

As a preferred embodiment of the polyurethane reworking adhesive, the silylated polyurethane prepolymer is a compound represented by formula (I), and the compound represented by formula (I) has the following structural formula:

r in the formula (I) is one of methyl-end dialkoxy, methyl-end trialkoxy, phenyl-end dialkoxy and phenyl-end trialkoxy.

The silanized polyurethane prepolymer disclosed by the invention is composed of two bonds and chains (namely Si-O-Si bonds and polyurethane chains) with different chemical structures, so that the system is endowed with excellent tensile strength, excellent elasticity and tear strength, Si-OH generated after hydrolysis of Si-OR of a terminal group is easy to chemically react with organic silicon, acrylate and polyurethane in LOCA optical residual adhesive to form effective adhesion, the LOCA residual adhesive can be removed under the condition of not causing new residues, the curing mechanism is moisture curing, the defect of damage to a touch screen caused by overhigh rework temperature can be avoided, and the rework yield is improved.

As a preferred embodiment of the polyurethane reworking adhesive, the viscosity of the silanized polyurethane prepolymer is 3000-8000 cps.

As a preferred embodiment of the polyurethane rework glue of the invention, the filler is at least one of white carbon black, silica micropowder, aluminum hydroxide, titanium dioxide, nano calcium carbonate, mica powder and carbon black.

As a preferred embodiment of the polyurethane reworking glue of the present invention, the crosslinking agent is one of methyltrimethoxysilane, methyltriethoxysilane, vinyltrimethoxysilane and tetramethoxysilane.

As a preferred embodiment of the polyurethane rework adhesives of the invention, the catalyst is an organotin catalyst such as dibutyltin diacetate, dibutyltin dilaurate, dioctyltin dilaurate, stannous octoate, dialkyltin bis (beta-diketo esters); titanate and its coordination catalyst such as one of monoalkoxy titanate, polyalkoxy titanate, dialkoxy titanium bis (beta-diketo ester) coordination compound, and titanic acid glycol ester beta-diketone coordination compound.

As a preferred embodiment of the polyurethane rework adhesive of the present invention, the water scavenger is one of tosyl isocyanate, triethyl orthoformate, vinyl trimethoxy silane, vinyl triethoxy silane, 3-ethyl-2-methyl-2- (3-methylbutyl) -1, 3-oxazolidine, etc., preferably vinyl trimethoxy silane.

The invention provides a preparation method of polyurethane reworking glue, which comprises the following steps:

(1) uniformly mixing the silanized polyurethane prepolymer, a filler and a water removing agent by a kneading machine, and removing excessive water in the system by high-temperature vacuum dehydration treatment;

(2) transferring the mixture into a planetary reaction kettle, adding a cross-linking agent under the vacuum of-0.085 to-0.095 mpa, and stirring for 15-40 min; adding a catalyst and continuously stirring for 15-40 min; vacuumizing to remove bubbles, and packaging to obtain the polyurethane reworking adhesive.

The invention has the beneficial effects that:

the main chain of the polyurethane reworking adhesive is of a polyurethane structure, the end group is a polyalkoxy group, the polyurethane reworking adhesive has high tensile strength, excellent elasticity, a room-temperature curing mechanism and good bonding strength, has good bonding property to LOCA residual adhesive, is rapidly cured at room temperature, can rapidly remove the LOCA residual adhesive on the surface of a reworked touch screen, and improves the reworking yield of the touch screen.

Detailed Description

To better illustrate the objects, aspects and advantages of the present invention, the present invention will be further described with reference to specific examples.

The raw materials in the following examples are all commercially available general-purpose materials unless otherwise specified.

Examples 1 to 7 and comparative examples 1 to 2

The compositions of the polyurethane rework adhesives of examples 1-7 and comparative examples 1-2 are shown in Table 1. The preparation method of the polyurethane reworking glue in the embodiment 1-7 comprises the following steps:

(1) uniformly mixing the silanized polyurethane prepolymer, the pigment, the filler and the water removal agent by a kneading machine, and removing excessive water in the system by high-temperature vacuum dehydration treatment;

The structural formula of the silanized polyurethane prepolymer is shown as the following (I):

r in the formula can be 1 of methyl-terminated dialkoxy, methyl-terminated trialkoxy, phenyl-terminated dialkoxy and phenyl-terminated trialkoxy.

TABLE 1

The applicant further tested the performance of the polyurethane reworking adhesives of the above examples 1 to 7 and comparative examples 1 to 2. The test samples prepared in the above examples 1 to 7 and comparative examples 1 to 2 were subjected to surface curing time, hardness, shear strength, tensile strength, and elongation test, and the specific test methods were as follows:

the surface cure time of the material was tested according to WI-09-07; testing the hardness of the material according to GB/T531-08; testing the shear strength of the material according to GB/T7124-08; preparing the polyurethane reworked glue into a sample piece with the thickness of 2mm, and testing the tensile strength and the elongation of the material according to GB/T528-09 after the polyurethane reworked glue is completely cured; the tear strength of the material was tested according to GB/T529-2008; the testing method for removing the LOCA adhesive residues comprises the steps of coating the reworked adhesive provided by the invention on a reworked touch screen with the LOCA adhesive residues in a coating and scraping mode, standing for 1 day at room temperature until the adhesive is cured, slowly pulling up the adhesive along a coating route at the edge of the touch screen by using tweezers, quickly removing the LOCA adhesive residues on the touch screen, and observing the removal condition of the LOCA adhesive residues on the touch screen.

The performance test results of the polyurethane reworking adhesives of examples 1 to 7 and comparative examples 1 to 2 are shown in Table 2.

TABLE 2

As shown in table 1, the polyurethane reworked adhesive prepared in embodiments 1 to 7 of the present invention is rapidly cured at room temperature, has excellent tensile strength and tear strength, high hardness and good bonding strength, and can remove LOCA residual adhesive by more than 96%. In comparative examples 1 to 2, the content of the silylated polyurethane prepolymers is different from the range of the invention, and the performance of the silylated polyurethane prepolymers is reduced to a certain extent compared with the performance of the silylated polyurethane prepolymers, which shows that the effect of the silylated polyurethane prepolymers can be achieved only within a specific proportion range.

The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents, improvements and the like made within the spirit and principle of the present invention should be included in the scope of the present invention.

Claims

1. A polyurethane reworking adhesive is characterized by comprising a silanized polyurethane prepolymer, a filler, a cross-linking agent, a catalyst and a water removal agent; the components are calculated according to the following parts by weight: 100 parts of silanized polyurethane prepolymer, 10-26 parts of filler, 3-4.5 parts of cross-linking agent, 0.2-0.35 part of catalyst and 0.01-0.08 part of water removing agent; the terminal group of the silanized polyurethane prepolymer is a multi-alkoxy group, and the alkoxy group is connected with Si.

2. The polyurethane rework glue of claim 1, wherein the viscosity of the silylated polyurethane prepolymer is 3000-8000 cps.

3. The polyurethane rework glue of claim 1, wherein the filler is at least one of white carbon black, silica powder, aluminum hydroxide, titanium dioxide, nano calcium carbonate, mica powder and carbon black.

4. The polyurethane rework glue of claim 1, wherein the cross-linking agent is one of methyltrimethoxysilane, methyltriethoxysilane, vinyltrimethoxysilane, and tetramethoxysilane.

5. The polyurethane rework glue of claim 1, wherein the catalyst is an organotin catalyst or a titanate and its coordination catalyst.

6. The polyurethane rework glue of claim 5, wherein the organotin catalyst is dibutyltin diacetate, dibutyltin dilaurate, dioctyltin dilaurate, stannous octoate, dialkyltin bis (β -diketonate); the titanate and its coordination catalyst is monoalkoxy titanate, polyalkoxy titanate, dialkoxy titanium bis (beta-diketone ester) coordination compound, and titanic acid dihydric alcohol ester beta-diketone coordination compound.

7. The polyurethane rework glue of claim 1, wherein the water scavenger is one of tosyl isocyanate, triethyl orthoformate, vinyl trimethoxysilane, vinyl triethoxysilane, 3-ethyl-2-methyl-2- (3-methylbutyl) -1, 3-oxazolidine.

8. The polyurethane rework glue of claim 7, wherein the water scavenger is vinyltrimethoxysilane.

9. A method for preparing the polyurethane rework glue of any one of claims 1 to 8, characterized by comprising the steps of:

(2) transferring the mixture into a planetary reaction kettle, adding a cross-linking agent under the vacuum condition of-0.085 to-0.095 mpa, and stirring for 15 to 40 min; adding a catalyst and continuously stirring for 15-40 min; vacuumizing to remove bubbles, and packaging to obtain the polyurethane reworking adhesive.