Thermal tackifying pressure-sensitive adhesive composition and pressure-sensitive adhesive

Abstract

The invention provides a thermal tackifying pressure-sensitive adhesive composition. The thermal tackifying pressure-sensitive adhesive composition is prepared from the following components: an acrylate copolymer, double-end vinyl terminated isocyanate and a basic amine compound, wherein relative to 100 parts by weight of the acrylate copolymer, the content of the double-end vinyl terminated isocyanate is 0.5-3 parts by weight, and the content of the alkaline amine compound is 0.5-12 parts by weight. The pressure-sensitive adhesive prepared from the heat-tackifying pressure-sensitive adhesive composition disclosed by the invention is relatively low in initial stripping force, can be torn at will after being adhered, and has a positioning function; and after adhesion, through high temperature, the stripping force is improved, and the high adhesion performance required by a fixed part is achieved, so that the part loss caused by errors in the initial stage of adhesion is reduced, and the high-viscosity pressure-sensitive adhesive can be suitable for application occasions of conventional high-viscosity pressure-sensitive adhesives.

Description

Technical Field

[0001] The invention relates to the technical field of pressure-sensitive adhesives, and in particular to a heat-tackifying pressure-sensitive adhesive composition and a pressure-sensitive adhesive. Background Art

[0002] Pressure-sensitive adhesive is a kind of adhesive that is sensitive to pressure, also known as self-adhesive adhesive; it has the advantages of good temperature resistance, wide range of peel strength, strong cohesion, good chemical resistance and aging resistance, and wide range of applications. Therefore, it is often used in the bonding and protection of the industrial and electronic industries, such as: fixing and laminating electronic components, bonding batteries and their inner shells, etc. Moreover, this type of pressure-sensitive adhesive usually has high viscosity, and its peel force is generally around 15N. It is not convenient to reposition or adjust the position after a wrong lamination, and once lamination is completed, it is difficult to tear off the adhesive layer without damaging the components, thus causing component loss. Summary of the invention

[0003] Based on the above problems, the present invention provides a heat-tackifying pressure-sensitive adhesive composition and a pressure-sensitive adhesive prepared from the heat-tackifying pressure-sensitive adhesive composition. The pressure-sensitive adhesive prepared from the heat-tackifying pressure-sensitive adhesive composition of the present invention has a low peeling force in the initial stage of lamination, which can ensure that it can be torn off at will after lamination, and is convenient for positioning and adjustment; after lamination, the peeling force will be improved by high temperature to achieve the high adhesion performance required for component fixation, thereby reducing component loss caused by lamination errors in the initial stage of lamination, and can be applicable to conventional high-viscosity pressure-sensitive adhesive applications.

[0004] To achieve the above purpose, the technical solution adopted by the present invention is as follows:

[0005] The first aspect of the present invention provides a heat-tackifying pressure-sensitive adhesive composition, which comprises the following components: an acrylate copolymer, a double-end vinyl-terminated isocyanate, and a basic amine compound;

[0006] Wherein, relative to 100 parts by weight of the acrylic ester copolymer, the content of the double-end vinyl-terminated isocyanate is 0.5 to 3 parts by weight, and the content of the basic amine compound is 0.5 to 12 parts by weight.

[0007] The second aspect of the present invention provides a pressure-sensitive adhesive, which contains the heat-tackifying pressure-sensitive adhesive composition described in the first aspect of the present invention.

[0008] Through the above technical solution, the present invention has at least the following advantages compared with the prior art:

[0009] (1) A double-end vinyl-terminated isocyanate is added to the heat-tackifying pressure-sensitive adhesive composition provided by the present invention. This type of double-end vinyl-terminated isocyanate can be grafted onto the molecular chain of the acrylate copolymer through a UV free radical reaction, thereby increasing the crosslinking density of the pressure-sensitive adhesive in the initial stage of use, so that the modulus of the pressure-sensitive adhesive in the initial stage of use is high and the peel force is low, and it is convenient to tear off at any time after bonding, so that it is suitable for initial positioning.

[0010] (2) After the initial positioning and accurate bonding, the double-end vinyl-terminated isocyanate added to the heat-tackifying pressure-sensitive adhesive composition provided by the present invention is subjected to high-temperature treatment (110-150°C), which can break the molecular chains formed in the initial bonding stage, thereby reducing the cross-linking density and modulus of the pressure-sensitive adhesive, and its peel force can be increased to a high viscosity level, so that it can be suitable for all conventional high-viscosity pressure-sensitive adhesive applications.

[0011] The endpoints and any values ​​of the ranges disclosed in this article are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of each range, the endpoint values ​​of each range and the individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this article. DETAILED DESCRIPTION

[0012] The specific embodiments of the present invention are described in detail below. It should be understood that the specific embodiments described herein are only used to illustrate and explain the present invention, and are not used to limit the present invention.

[0013] The first aspect of the present invention provides a heat-tackifying pressure-sensitive adhesive composition, which comprises the following components: an acrylate copolymer, a double-end vinyl-terminated isocyanate and an alkaline amine compound; wherein, relative to 100 parts by weight of the acrylate copolymer, the content of the double-end vinyl-terminated isocyanate is 0.5 to 3 parts by weight, and the content of the alkaline amine compound is 0.5 to 12 parts by weight.

[0014] Current pressure-sensitive adhesives generally have high viscosity, and the peeling force at the initial stage of lamination is about 15N. When the lamination is wrong and you want to reposition it, it is difficult to tear it off without damaging the parts. Therefore, based on the above problems in the prior art, the present invention provides a heat-tackifying pressure-sensitive adhesive composition, which adds a double-end vinyl-terminated isocyanate to the components. The double-end vinyl-terminated isocyanate can be grafted onto the molecular chain of the acrylate copolymer through UV free radical reaction, thereby increasing the crosslinking density of the pressure-sensitive adhesive in the initial stage of use, so that the pressure-sensitive adhesive has a high modulus and a low peeling force in the initial stage of use, and can be torn off at will after lamination, so as to be suitable for initial positioning.

[0015] Furthermore, after the double-end vinyl-terminated isocyanate has completed the initial positioning and accurate bonding, it is subjected to high-temperature treatment (110-150°C), which can break the molecular chains formed in the initial bonding, thereby reducing the cross-linking density and modulus of the pressure-sensitive adhesive, and its peel force can be increased to a high viscosity level, making it suitable for all conventional high-viscosity pressure-sensitive adhesive applications.

[0016] In addition, during the high-temperature treatment process, the double-end vinyl-terminated isocyanate will cross-link with water in the air due to the relatively high activity of the isocyanate groups in the system, thereby resulting in an increase in the modulus and a decrease in the later viscosity. To avoid this situation, the present invention also adds an alkaline amine compound to the heat-tackifying pressure-sensitive adhesive composition. This compound has a high boiling point and can consume the isocyanate groups in the system to generate amino formic acid, thereby avoiding the cross-linking of the isocyanate groups in the system with water molecules, improving the later viscosity of the heat-tackifying pressure-sensitive adhesive, and making it more in line with the market demand for high viscosity performance.

[0017] Furthermore, in order to increase the initial crosslinking density between the double-end vinyl-blocked isocyanate and the acrylic ester copolymer, the content of the double-end vinyl-blocked isocyanate is 0.5 to 3 parts by weight relative to 100 parts by weight of the acrylic ester copolymer. Specifically, the content of the double-end vinyl-blocked isocyanate can be 0.5 parts by weight, 0.6 parts by weight, 0.7 parts by weight, 0.8 parts by weight, 0.9 parts by weight, 1 part by weight, 1.1 parts by weight, 1.2 parts by weight, 1.3 parts by weight, 1.4 parts by weight, 1.5 parts by weight, 1.6 parts by weight, 1.7 parts by weight, 1.8 parts by weight, 1.9 parts by weight, 2 parts by weight, 2.1 parts by weight, 2.2 parts by weight, 2.3 parts by weight, 2.4 parts by weight, 2.5 parts by weight, 2.6 parts by weight, 2.7 parts by weight, 2.8 parts by weight, 2.9 parts by weight, 3 parts by weight or any value between any two of the above values, preferably 1 to 2.5 parts by weight. When the content of double-end vinyl-blocked isocyanate and alkaline amine compound is excessive relative to the content of acrylate copolymer, the crosslinking density will be too high, but at the same time, too much alkaline amine will lead to too many small molecules in the system, making the colloid soft and easy to precipitate, thereby contaminating the adhered object; when the content of double-end vinyl-blocked isocyanate is too low relative to the content of acrylate copolymer, the amount of double-end vinyl-blocked isocyanate that can be grafted to the acrylate copolymer is too small, and the effect of improving the initial crosslinking density is not good, resulting in the pressure-sensitive adhesive still having a high peel force in the initial stage, which is difficult to tear off after adhesion and is not suitable for repositioning after bonding errors.

[0018] Furthermore, in order to improve the viscosity of the heat-tackified pressure-sensitive adhesive after high temperature treatment and make it have high viscosity, the content of the basic amine compound is 0.5 to 12 parts by weight relative to 100 parts by weight of the acrylate copolymer. Specifically, the content of the basic amine compound can be 0.5 parts by weight, 1 part by weight, 1.25 parts by weight, 2 parts by weight, 2.5 parts by weight, 3.5 parts by weight, 4 parts by weight, 5 parts by weight, 5.5 parts by weight, 6 parts by weight, 6.5 parts by weight, 7 parts by weight, 7.5 parts by weight, 8 parts by weight, 8.5 parts by weight, 9 parts by weight, 10 parts by weight, 12 parts by weight or any value between any two of the above value ranges, preferably 2.5 to 6 parts by weight. When the content of alkaline amine compounds is excessive, too many small molecules will affect the initial viscosity, resulting in high peel force, poor rework performance and die-cutting overflow; when the content of alkaline amine compounds is too low, the isocyanate groups in the system cannot be completely consumed, and the highly active isocyanate groups will cross-link with water in the air, resulting in increased modulus and reduced viscosity in the later stage, unstable product performance and poor practical performance.

[0019] In a specific embodiment, the weight ratio of the basic amine compound to the double-end vinyl-terminated isocyanate is (1-4):1. Specifically, the weight ratio of the basic amine compound to the double-end vinyl-terminated isocyanate can be 1:1, 1.5:1, 2:1, 2.5:1, 3:1, 3.5:1, 4:1 or any ratio between any two end values ​​of the above, preferably (2-3):1. Since the excess isocyanate group will continue to react with the amino formic acid generated by the basic amine compound to generate urea, the modulus of the pressure-sensitive adhesive will increase, resulting in a decrease in the later viscosity. Therefore, by further controlling the weight ratio of the basic amine compound to the double-end vinyl-terminated isocyanate, it is possible to ensure that the amount of the basic amine compound is slightly greater than the amount of the isocyanate group, thereby avoiding the reaction of the excess isocyanate group with the amino formic acid.

[0020] In a specific embodiment, the basic amine compound includes at least one of dipropylamine and cyclohexylamine. In a preferred embodiment, the basic amine compound is selected from dipropylamine.

[0021] The present invention also provides a method for preparing the double-end vinyl-terminated isocyanate, which is specifically as follows: adding compound 1 into a reaction container, then adding an antioxidant and a first catalyst and mixing them evenly, introducing an inert gas, and then adding compound 2 to react, thereby preparing the double-end vinyl-terminated isocyanate;

[0022] Wherein, the structural formula of compound 1 is shown in the following formula (1) or the following formula (2), and the structural formula of compound 2 is shown in the following formula (3):

[0023]

[0024] Wherein, n is an integer between 4 and 10. In a specific embodiment, n can be 4, 5, 6, 7, 8, 9 or 10, preferably 6;

[0025]

[0026] Wherein, p is an integer between 1 and 4. In a specific embodiment, p can be 1, 2, 3 or 4, preferably 2;

[0027]

[0028] Wherein, R1 is a hydrogen atom or a methyl group, and m is an integer between 1 and 4. In a specific embodiment, m can be 1, 2, 3 or 4, preferably 2 or 3.

[0029] In a preferred preparation method, the molar ratio of compound 1 to compound 2 is 1:1.

[0030] In a preferred preparation method, the mixing temperature of the compound 1, the antioxidant and the first catalyst is maintained at a constant temperature of 15°C.

[0031] In a preferred preparation method, the inert gas is nitrogen.

[0032] In a preferred preparation method, the reaction temperature for adding compound 2 for reaction is 15-20° C. Specifically, the reaction temperature is 15° C., 16° C., 17° C., 18° C., 19° C. or 20° C., or any value between the two end values.

[0033] In a preferred preparation method, the compound 2 is added dropwise at a uniform rate.

[0034] In a preferred preparation method, after the dropwise addition of compound 2 is completed, the reaction temperature is maintained at 20° C. and the reaction is continued for 12 hours.

[0035] In a preferred preparation method, the antioxidant is butylated hydroxytoluene, and its added amount is 0.01 to 0.1 g relative to 1 mol of compound 1. Specifically, its added amount can be 0.01 g, 0.02 g, 0.03 g, 0.04 g, 0.05 g, 0.06 g, 0.07 g, 0.08 g, 0.09 g, 0.1 g, or any value between the two end values, preferably 0.05 g.

[0036] In a preferred preparation method, the first catalyst is dibutyltin disilicate, and its addition amount is 0.05-0.2g relative to 1 mol of compound 1. Specifically, its addition amount can be 0.05g, 0.06g, 0.07g, 0.08g, 0.09g, 0.1g, 0.12g, 0.14g, 0.16g, 0.18g, 0.2g, or any value between the two end values, preferably 0.1g.

[0037] In a preferred preparation method, compound 1 adopts the structure of formula (1), and n=6; compound 2 adopts the structure of formula (3), and m=3, and R1 is methyl; the prepared double-end vinyl-terminated isocyanate is propyl methacrylate isocyanate (3-octenyl-phenol), and its structure is shown in the following formula (4):

[0038]

[0039] In a preferred preparation method, compound 1 adopts the structure of formula (1), and n=6; compound 2 adopts the structure of formula (3), and m=3, and R1 is a hydrogen atom; the prepared double-end vinyl-terminated isocyanate is propyl acrylate isocyanate (3-octenyl-phenol), and its structure is shown in the following formula (5):

[0040]

[0041] In a preferred preparation method, compound 1 adopts the structure of formula (2), and p=2; compound 2 adopts the structure of formula (3), and m=2, and R1 is a hydrogen atom; the prepared double-end vinyl-terminated isocyanate is (1-methyl-4-pentene) cyanoacrylate ethyl isocyanate, and its structure is shown in the following formula (6):

[0042]

[0043] In a preferred preparation method, compound 1 adopts the structure of formula (2), and p=2; compound 2 adopts the structure of formula (3), and m=2, and R1 is methyl; the prepared double-end vinyl-terminated isocyanate is (1-methyl-4-pentene) cyanated ethyl methacrylate isocyanate, and its structure is shown in the following formula (7):

[0044]

[0045] In the present invention, the above-mentioned double-end vinyl-blocked isocyanates are not limited thereto, and double-end vinyl-blocked isocyanates of different structures can be prepared according to compounds of different structures. The double bond groups at both ends of the double-end vinyl-blocked isocyanate include vinyl groups and / or isopropenyl groups, that is, both ends of the double-end vinyl-blocked isocyanate can be vinyl groups at the same time, or one end can be a vinyl group and the other end can be an isopropenyl group.

[0046] In a specific embodiment, based on 100 wt % of the total amount of constituent monomers of the acrylic ester copolymer, the acrylic ester copolymer includes the following monomer components: 5 to 15 wt % of hard monomers and 85 to 95 wt % of soft monomers.

[0047] In a specific embodiment, based on the total amount of constituent monomers of the acrylic ester copolymer as 100wt%, the hard monomer accounts for 5 to 15wt%, specifically 5wt%, 8wt%, 10wt%, 11wt%, 12wt%, 13wt%, 14wt% or 15wt%, or any value between the two end values, preferably 8 to 12wt%.

[0048] In a specific embodiment, the hard monomer includes at least one of methyl (meth)acrylate, styrene, acrylic acid, vinyl acetate, ethyl methacrylate, isobutyl methacrylate, acrylonitrile, cyclohexyl methacrylate, and isobornyl methacrylate.

[0049] In a specific embodiment, based on the total amount of monomers constituting the acrylic ester copolymer as 100wt%, the soft monomer accounts for 85-95wt%, specifically 85wt%, 88wt%, 90wt%, 92wt% or 95wt%, or any value between the two ends, preferably 88-92wt%.

[0050] In a specific embodiment, the soft monomer includes at least one of butyl acrylate, isooctyl acrylate, ethyl acrylate, n-octyl acrylate, and lauryl (meth)acrylate.

[0051] In a specific embodiment, the acrylate copolymer also includes a first initiator. Relative to 100 parts by weight of the total amount of monomers constituting the acrylate copolymer, the content of the first initiator is 0.1 to 0.5 parts by weight, specifically 0.1 parts by weight, 0.2 parts by weight, 0.3 parts by weight, 0.4 parts by weight or 0.5 parts by weight, or any value between the two end values, preferably 0.1 to 0.3 parts by weight.

[0052] In a specific embodiment, the first initiator includes at least one of benzoin and its derivatives, benzil derivatives, acetophenone derivatives, α-hydroxyalkyl phenones, α-amino ketone derivatives, and acylphosphine oxides. In a preferred embodiment, the first initiator is selected from α-hydroxyalkyl phenones. In a specific embodiment, the first initiator is selected from 1-hydroxycyclohexyl phenyl ketone (UV-184).

[0053] In a specific embodiment, the acrylic ester copolymer also includes a chain transfer agent. Relative to 100 parts by weight of the total amount of the acrylic ester copolymer constituent monomers, the content of the chain transfer agent is 0.01 to 0.3 parts by weight, specifically 0.01 parts by weight, 0.1 parts by weight, 0.15 parts by weight, 0.2 parts by weight or 0.3 parts by weight, or any value between the two end values, preferably 0.1 to 0.2 parts by weight.

[0054] In a specific embodiment, the chain transfer agent includes one or more of isooctyl 3-mercaptopropionate, n-dodecyl mercaptan, and tert-dodecyl mercaptan.

[0055] The present invention also provides a method for preparing an acrylate copolymer. Specifically, the method for preparing the acrylate copolymer can be carried out in the following manner: the soft monomer, hard monomer, first initiator and chain transfer agent are added into a reaction kettle, mixed evenly, and a UVLED light source is used to initiate the polymerization reaction of the monomers, and the acrylate copolymer can be obtained after the reaction is completed.

[0056] In a preferred preparation method, the irradiation distance of the UVLED light source is 20 to 30 cm.

[0057] In a preferred preparation method, the wavelength of the UVLED lamp can be 365nm and the light intensity can be 82mW / cm 2 .

[0058] In a preferred preparation method, the reaction temperature of the polymerization reaction is 5-15°C, specifically 5°C, 7°C, 10°C, 13°C or 15°C, or any value between the two end values.

[0059] In a preferred preparation method, the viscosity of the prepared acrylic ester copolymer is 3,000 to 6,000 cPs. In the present invention, the viscosity of the copolymer is controlled within this range for ease of coating.

[0060] In a specific embodiment, the heat-adhesive pressure-sensitive adhesive composition further includes a second initiator, and the content of the second initiator is 0.01 to 0.8 parts by weight relative to 100 parts by weight of the acrylate copolymer, and can be specifically 0.01 parts by weight, 0.1 parts by weight, 0.2 parts by weight, 0.3 parts by weight, 0.4 parts by weight, 0.5 parts by weight, 0.6 parts by weight, 0.7 parts by weight or 0.8 parts by weight, or any value between the two end values, preferably 0.1 to 0.3 parts by weight. The second initiator can induce the double-end vinyl-terminated isocyanate to undergo UV free radical reaction and be grafted onto the molecular chain of the acrylate copolymer, thereby increasing the initial crosslinking density of the pressure-sensitive adhesive and reducing the peeling force.

[0061] In one embodiment, the second initiator includes at least one of benzoin and its derivatives, benzil derivatives, acetophenone derivatives, α-hydroxyalkyl phenones, α-amino ketone derivatives, and acylphosphine oxides. In a preferred embodiment, the second initiator is selected from α-hydroxyalkyl phenones. In one embodiment, the first initiator is selected from 1-hydroxycyclohexyl phenyl ketone.

[0062] In a specific embodiment, the heat-adhesive pressure-sensitive adhesive composition further includes a second catalyst, and the content of the second catalyst is 0.1 to 1 part by weight relative to 100 parts by weight of the acrylate copolymer, and can be specifically 0.1 parts by weight, 0.2 parts by weight, 0.3 parts by weight, 0.4 parts by weight, 0.5 parts by weight, 0.6 parts by weight, 0.7 parts by weight, 0.8 parts by weight or 1 part by weight, or any value between the two end values, preferably 0.2 to 0.5 parts by weight. The second catalyst can be used to promote the unblocking of the double-end vinyl-terminated isocyanate at the high temperature stage, so that the double-end vinyl-terminated isocyanate breaks from the molecular chain of the acrylate copolymer, reduces the cross-linking density of the pressure-sensitive adhesive in the later stage, and improves the peeling force, thereby quickly improving the viscosity in the later stage of lamination.

[0063] In a specific embodiment, the second catalyst is a metal salt catalyst, and the metal salt catalyst may include at least one of dibutyltin dilaurate and dibutyltin diacetate. In a preferred embodiment, the second catalyst is selected from dibutyltin dilaurate.

[0064] In a specific embodiment, the heat-adhesive pressure-sensitive adhesive composition further includes a crosslinking monomer, and the content of the crosslinking monomer is 0 to 3 parts by weight relative to 100 parts by weight of the acrylate copolymer, and can be specifically 0 parts by weight, 0.1 parts by weight, 0.2 parts by weight, 0.3 parts by weight, 0.5 parts by weight, 1 parts by weight, 1.5 parts by weight, 2 parts by weight, 2.5 parts by weight or 3 parts by weight, or any value between the two end values, preferably 0.1 to 2 parts by weight. In the present invention, the crosslinking monomer may not be added, and the double-end vinyl-terminated isocyanate can play a crosslinking role; and after the crosslinking monomer is added, the acrylate copolymer is partially crosslinked with the crosslinking monomer and partially with the double-end vinyl-terminated isocyanate, and its crosslinking effect is stronger.

[0065] In a specific embodiment, the crosslinking monomer is selected from at least one of 1,6-hexanediol diacrylate (HDDA) and polyurethane acrylate. The polyurethane acrylate can be selected from difunctional and / or trifunctional polyurethane acrylate.

[0066] The second aspect of the present invention provides a pressure-sensitive adhesive, which comprises the heat-tackifying pressure-sensitive adhesive composition described in the first aspect of the present invention, or a pressure-sensitive adhesive prepared from the heat-tackifying pressure-sensitive adhesive composition.

[0067] The present invention further provides an adhesive sheet, which is prepared from the pressure-sensitive adhesive described in the second aspect of the present invention, or contains the heat-tackifying pressure-sensitive adhesive composition described in the first aspect of the present invention.

[0068] The present invention also provides a protective film, which comprises a substrate layer and an adhesive layer arranged on at least one surface of the substrate layer, wherein the adhesive layer is the above-mentioned adhesive sheet.

[0069] In the present invention, the product is limited to a protective film based on actual use. In fact, as long as it contains the heat-adhesive pressure-sensitive adhesive composition of the present invention, it can also be designed as other products. For example, the protective film can also be a heat-adhesive pressure-sensitive adhesive tape, a heat-adhesive pressure-sensitive adhesive label paper, a heat-adhesive pressure-sensitive adhesive sheet, a heat-adhesive pressure-sensitive adhesive film, etc.

[0070] In a specific embodiment, a release film layer is disposed on a surface of the adhesive layer facing away from the substrate layer.

[0071] In a specific embodiment, the thickness of the substrate layer is 12 to 100 μm, specifically 12 μm, 20 μm, 25 μm, 30 μm, 50 μm, 70 μm, 75 μm, 80 μm or 100 μm, preferably 25 to 75 μm.

[0072] In a specific embodiment, the thickness of the adhesive layer is 20 to 200 μm, specifically 20 μm, 25 μm, 30 μm, 50 μm, 70 μm, 75 μm, 80 μm, 100 μm or 200 μm, preferably 20 to 75 μm.

[0073] In a specific embodiment, the thickness of the release film layer is 25 to 75 μm, specifically 25 μm, 30 μm, 38 μm, 40 μm, 50 μm, 60 μm, 65 μm, 70 μm or 75 μm, preferably 38 to 50 μm.

[0074] In the present invention, the material of the substrate layer is not specifically limited, and materials commonly used as tape substrates in the art can be selected. For example, the substrate layer can be polyethylene terephthalate (PET), polyimide (PI), and the like.

[0075] In the present invention, the release film layer can be selected from one or more of PET (polyethylene terephthalate), PE (polyethylene), and OPP (bidirectional polypropylene). Since the release film layer only plays a release role, it is convenient for product packaging and transportation. When it is actually attached and used, the release layer will be torn off to make the adhesive layer attached to the surface of the attached object. Therefore, the thickness of the release film layer is not limited in the present invention, and a suitable thickness can be selected according to actual use requirements.

[0076] The present invention also provides a method for preparing a protective film, which specifically comprises the following steps: coating the pressure-sensitive adhesive on the surface of the substrate layer, drying and curing the substrate, and then laminating with a release film to obtain the protective film having the heat-adhesive pressure-sensitive adhesive layer.

[0077] In a preferred preparation method, the curing adopts UVLED light curing, the wavelength of the curing lamp light source adopted is 365nm, the light power is 18W, the curing time is 4 to 8min, and the lamp irradiation distance is 8 to 12cm.

[0078] The present invention will be described in further detail below in conjunction with specific embodiments. It should be understood that the following embodiments are only exemplary descriptions and explanations of the present invention and should not be construed as limiting the scope of protection of the present invention. All technologies implemented based on the above content of the present invention are included in the scope that the present invention is intended to protect.

[0079] Unless otherwise specified, the experimental methods used in the following examples are all conventional methods; the reagents, materials, etc. used in the following examples, unless otherwise specified, can be obtained from commercial channels.

[0080] In order to make the purpose, technical solutions and advantages of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in combination with the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0081] In the following examples, unless otherwise specified, all components used were commercially available analytically pure. 1 g represents 1 part by weight.

[0082] Preparation of Acrylate Copolymer

[0083] Preparation Example Group A

[0084] This preparation example is used to prepare an acrylic ester copolymer. Each group only differs in the content of the components, and the preparation method is the same. The content of the substances in each preparation example is shown in Table 1:

[0085] Table 1 Content of each component of acrylic ester copolymer (the unit of each component content is g)

[0086]

[0087] Preparation method: Weigh butyl acrylate, acrylic acid, methyl methacrylate, 1-hydroxycyclohexyl phenyl ketone (UV-184) and n-dodecyl mercaptan in parts by weight and add them into a reaction kettle, mix them evenly, introduce nitrogen gas for 30 minutes, and use a UVLED light source to initiate monomer polymerization. The distance between the UVLED light source and the bottom of the bottle is fixed at 25 cm, wherein the wavelength of the UVLED lamp is 365 nm, and the light intensity is 82 mW / cm 2 , the reaction temperature is controlled in the range of 5-15°C to obtain the acrylic ester copolymer.

[0088] Preparation of double-terminal vinyl-terminated isocyanate:

[0089] Preparation Example Group B

[0090] This group of preparation examples is used to prepare double-end vinyl-terminated isocyanate. In different preparation examples, only the specific substances and amounts of compound 1 and compound 2 are different, and other components and preparation methods are the same, as shown below:

[0091] Preparation method: Add 1 mol of compound 1, 0.05 g of butylated hydroxytoluene, and 0.1 g of dibutyltin dilaurate into a reaction container, stir at a constant temperature of 15°C, blow dry nitrogen, add 1 mol of compound 2 dropwise, maintain the reaction temperature in the range of 15-20°C, add dropwise at a uniform rate for 1 hour, maintain 20°C after the addition is completed, and react for 12 hours. After the reaction is completed, IR can be used to confirm whether the isocyanate group is completely consumed, and finally a double-end vinyl-terminated isocyanate compound is obtained, which has the appearance of a colorless transparent liquid.

[0092] Preparation Example B1: Compound 1 adopts the structure of formula (1), and n=6; Compound 2 adopts the structure of formula (3), and m=3, R1 is methyl; the structure of the prepared double-end vinyl-terminated isocyanate is:

[0093]

[0094] Preparation Example B2: Compound 1 adopts the structure of formula (1), and n=6; Compound 2 adopts the structure of formula (3), and m=3, R1 is a hydrogen atom; the structure of the prepared double-end vinyl-terminated isocyanate is:

[0095]

[0096] Preparation Example B3: Compound 1 adopts the structure of formula (2), and p=2; Compound 2 adopts the structure of formula (3), and m=2, R1 is a hydrogen atom; the structure of the prepared double-end vinyl-terminated isocyanate is:

[0097]

[0098] Preparation Example B4: Compound 1 adopts the structure of formula (2), and p=2; Compound 2 adopts the structure of formula (3), and m=2, R1 is methyl; the structure of the prepared double-end vinyl-terminated isocyanate is:

[0099]

[0100] Example 1

[0101] Preparation of pressure-sensitive adhesive: Weigh 100 g of the acrylate copolymer prepared in Preparation Example A1 and place it in a reaction kettle, add 2 g of the double-end vinyl-terminated isocyanate prepared in Preparation Example B1, 0.2 g of 1-hydroxycyclohexyl phenyl ketone, 5 g of dipropylamine, 0.3 g of dibutyltin dilaurate and 1.5 g of HDDA, stir evenly, and degas to obtain the heat-tackified pressure-sensitive adhesive.

[0102] Example 2

[0103] Example 2 was carried out with reference to Example 1, except that the raw material composition of the pressure-sensitive adhesive was different. The preparation method was the same as that of Example 1, and the specific differences were as follows:

[0104] 0.5 g of double-end vinyl-terminated isocyanate prepared in Preparation Example B1;

[0105] dipropylamine, 1.25 g;

[0106] 1-Hydroxycyclohexylphenyl ketone, 0.1 g;

[0107] Dibutyltin dilaurate, 0.1 g;

[0108] HDDA, 0.1 g.

[0109] Example 3

[0110] Example 3 was carried out with reference to Example 1, except that the raw material composition of the pressure-sensitive adhesive was different. The preparation method was the same as that of Example 1, and the specific differences were as follows:

[0111] 3 g of double-end vinyl-terminated isocyanate prepared in Preparation Example B1;

[0112] dipropylamine, 7.5 g;

[0113] 1-Hydroxycyclohexylphenyl ketone, 0.8 g;

[0114] Dibutyltin dilaurate, 1 g;

[0115] HDDA, 3g.

[0116] Example 4

[0117] Example 4 was carried out with reference to Example 1, except that the raw material composition of the pressure-sensitive adhesive was different. The preparation method was the same as that of Example 1, and the specific differences were as follows:

[0118] 1 g of double-end vinyl-terminated isocyanate prepared in Preparation Example B1;

[0119] dipropylamine, 2.5 g;

[0120] 1-Hydroxycyclohexylphenyl ketone, 0.1 g;

[0121] Dibutyltin dilaurate, 0.2 g;

[0122] HDDA, 1g.

[0123] Example 5

[0124] Example 5 was carried out with reference to Example 1, except that the raw material composition of the pressure-sensitive adhesive was different. The preparation method was the same as that of Example 1, and the specific differences were as follows:

[0125] 2.4 g of double-end vinyl-terminated isocyanate prepared in Preparation Example B1;

[0126] dipropylamine, 6 g;

[0127] 1-Hydroxycyclohexylphenyl ketone, 0.3 g;

[0128] Dibutyltin dilaurate, 0.5 g;

[0129] HDDA, 2g.

[0130] Example 6 Group

[0131] Example 6 was carried out in accordance with Example 1, except that a double-end vinyl-terminated isocyanate prepared in a different preparation example B was selected, and the preparation method and amount and other components thereof remained unchanged, as shown below:

[0132] Example 6-1: Using the double-end vinyl-terminated isocyanate prepared in Preparation Example B2;

[0133] Example 6-2: Using the double-end vinyl-terminated isocyanate prepared in Preparation Example B3;

[0134] Example 6-3: Using the double-end vinyl-terminated isocyanate prepared in Preparation Example B4.

[0135] Example 7 Group

[0136] Example 7 was carried out with reference to Example 1, except that the mass ratio of dipropylamine to double-end vinyl-terminated isocyanate was changed by adjusting the amount of dipropylamine added, and the other material compositions and preparation methods were the same as those in Example 1, with the specific differences as follows:

[0137] Example 7-1: dipropylamine, 2 g, the mass ratio of dipropylamine to double-terminated vinyl-terminated isocyanate is 1:1;

[0138] Example 7-2: dipropylamine, 8 g, the mass ratio of dipropylamine to double-terminated vinyl-terminated isocyanate is 4:1;

[0139] Example 7-3: dipropylamine, 4 g, the mass ratio of dipropylamine to double-terminated vinyl-terminated isocyanate is 2:1;

[0140] Example 7-4: dipropylamine, 6 g, the mass ratio of dipropylamine to double-terminated vinyl-terminated isocyanate is 3:1;

[0141] Example 7-5: dipropylamine, 10 g, the mass ratio of dipropylamine to double-terminated vinyl-terminated isocyanate is 5:1;

[0142] Example 7-6: dipropylamine, 1 g, the mass ratio of dipropylamine to double-terminated vinyl-terminated isocyanate is 0.5:1.

[0143] Example 8

[0144] Example 8 is carried out with reference to Example 1, except that the pressure-sensitive adhesive does not contain the cross-linking monomer HDDA. Other components and preparation methods are the same as those in Example 1.

[0145] Example 9 Group

[0146] Example 9 was carried out in accordance with Example 1, except that the acrylic acid ester copolymer prepared by the different preparation example A group was selected, and the preparation method and amount and other components thereof remained unchanged, as shown below:

[0147] Example 9-1: using the acrylic acid ester copolymer prepared in Preparation Example A2;

[0148] Example 9-2: using the acrylic acid ester copolymer prepared in Preparation Example A3;

[0149] Example 9-3: using the acrylic acid ester copolymer prepared in Preparation Example A4;

[0150] Example 9-4: The acrylic acid ester copolymer prepared in Preparation Example A5 was used.

[0151] Comparative Example 1

[0152] Comparative Example 1 was carried out with reference to Example 1, except that no double-end vinyl-terminated isocyanate was added to the pressure-sensitive adhesive.

[0153] Comparative Example 2

[0154] Comparative Example 2 was carried out with reference to Example 1, except that no dipropylamine was added to the pressure-sensitive adhesive.

[0155] Comparative Example 3

[0156] Comparative Example 3 was carried out with reference to Example 1, except that the raw material composition of the pressure-sensitive adhesive was different. The preparation method was the same as that of Example 1, and the specific differences are as follows:

[0157] 0.1 g of the double-end vinyl-terminated isocyanate prepared in Preparation Example B1; 0.25 g of dipropylamine, with the mass ratio of dipropylamine to double-end vinyl-terminated isocyanate maintained at 2.5:1.

[0158] Comparative Example 4

[0159] Comparative Example 4 was carried out with reference to Example 1, except that the raw material composition of the pressure-sensitive adhesive was different. The preparation method was the same as that of Example 1, and the specific differences are as follows:

[0160] 5 g of the double-end vinyl-terminated isocyanate prepared in Preparation Example B1; 12.5 g of dipropylamine, with the mass ratio of dipropylamine to double-end vinyl-terminated isocyanate maintained at 2.5:1.

[0161] Thermal tackifying pressure sensitive adhesive protective film test case

[0162] The pressure-sensitive adhesive prepared in the above embodiments and comparative examples was coated on a PET substrate with a thickness of 50 μm, and cured by irradiation with an ultraviolet lamp; irradiation conditions: the wavelength of the curing lamp light source was 365 nm, the light power was 18 W, the curing time was 6 min, and the distance from the lamp was 10 cm. After curing, a PET release film with a thickness of 50 μm was coated to obtain a heat-adhesive pressure-sensitive adhesive protective film with an adhesive layer thickness of 75 μm. The heat-adhesive pressure-sensitive adhesive protective films prepared in the above embodiments and comparative examples were subjected to the following tests:

[0163] (1) Initial / late peel force test

[0164] The peel strength test is carried out according to ASTM D3330 "Standard for Testing the Peel Strength of Pressure-Sensitive Tapes";

[0165] The above protective film was made into 25 mm wide strips, and the initial peeling force test was carried out according to the above test standard. The stripping force test was carried out on the steel plate at room temperature, and the data were recorded in Table 2;

[0166] The subsequent peel strength test was first subjected to high temperature treatment, and the adhesion increase operation steps were as follows: a 25 mm wide specimen made of the above protective film was placed in an environment of 140°C for high temperature treatment for 30 minutes, the wide specimen was taken out and allowed to stand at room temperature for 30 minutes, and then the steel plate was bonded for peel strength test, and the data were recorded in Table 2.

[0167] (2) Initial / late retention test

[0168] The holding force was tested according to ASTM D3330 "Standard for Testing the Peel Strength of Pressure-Sensitive Tapes". The specific operation was to cut a 25mm*10cm protective film strip, use a 2kg roller to stick it on a mirror steel plate at a speed of 300mm / min, let it stand for 20 minutes, and hang it in a holding force tester to observe the drop time (min).

[0169] Later retention test: Place the cut samples in an oven at 140°C for 30 minutes; take them out and place them at room temperature for two hours, then test the later retention in the same way as the initial method, and record the data in Table 2.

[0170] (3) Initial / late modulus test: room temperature rheological test

[0171] The pressure-sensitive adhesives prepared in each embodiment and comparative example were coated on a release film, and a 100 μm thick substrate-free adhesive layer was obtained after curing and drying. The adhesive layer was stacked to 900 μm, and the temperature sweep curve, i.e., the initial modulus, was tested using an Anton Paar rheometer. The adhesive layer was placed in an environment of 140° C. for high-temperature treatment for 30 min, and then taken out and allowed to stand at room temperature for 30 min before a rheological test was performed to obtain the later modulus. The scanning frequency of the rheometer test was 0.05 Hz, and the data were recorded in Table 2.

[0172] Table 2

[0173]

[0174]

[0175] It can be seen from the test results in Table 2 that the pressure-sensitive adhesive prepared in the present invention has a good tackifying effect, a high peeling force after heating, and good initial and later retention.

[0176] It can be seen from the test results of Example 6 that good pressure-sensitive adhesive tackifying performance can be obtained by using double-end vinyl-terminated isocyanates with different structures.

[0177] It can be seen from the test results of Example 7 that by controlling the mass ratio of the alkaline amine compound to the double-end vinyl-terminated isocyanate within a certain range, a pressure-sensitive adhesive with better tackification effect can be obtained. If it is lower than this ratio, the amount of double-end vinyl-terminated isocyanate is too large, resulting in low initial peeling force, poor initial bonding effect, and reduced practical performance; if it is higher than this ratio, the amount of alkaline amine is too large in the early stage, resulting in a soft colloid, high initial peeling force, poor rework performance, and poor retention and overflow of glue, resulting in poor practical performance.

[0178] It can be seen from the comparative examples that if the present invention does not contain double-end vinyl-blocked isocyanate, the initial peel force is high and the rework effect is not achieved; if the present invention does not contain alkaline amine compounds, the initial peel force is too low and normal bonding may not be possible; if the content of double-end vinyl-blocked isocyanate and alkaline amine compounds are both low, the low initial crosslinking degree will lead to a high initial peel force, which is not convenient for rework; if the content of double-end vinyl-blocked isocyanate and alkaline amine compounds are both high, the crosslinking density will be too high, and the increase in the small molecules of the alkaline amine compounds will cause the colloid to be soft, the overall modulus will be reduced, the initial peel force will be high, and excessive small molecules will migrate in actual use, resulting in contamination of the adhered object.

[0179] The preferred embodiments of the present invention are described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, the technical solution of the present invention can be subjected to a variety of simple modifications, including the combination of various technical features in any other suitable manner, and these simple modifications and combinations should also be regarded as the contents disclosed by the present invention and belong to the protection scope of the present invention.

Claims

1. A heat-tackifying pressure-sensitive adhesive composition, characterized in that: The heat-adhesive pressure-sensitive adhesive composition comprises the following components: an acrylate copolymer, a double-end vinyl-terminated isocyanate and a basic amine compound; Wherein, relative to 100 parts by weight of the acrylic ester copolymer, the content of the double-end vinyl-terminated isocyanate is 0.5 to 3 parts by weight, and the content of the basic amine compound is 0.5 to 12 parts by weight.

2. The heat-adhesive pressure-sensitive adhesive composition according to claim 1, wherein: The content of the double-end vinyl-terminated isocyanate is 1 to 2.5 parts by weight, and the content of the basic amine compound is 2.5 to 6 parts by weight, relative to 100 parts by weight of the acrylic ester copolymer.

3. The heat-adhesive pressure-sensitive adhesive composition according to claim 1, wherein: The weight ratio of the basic amine compound to the double-end vinyl-terminated isocyanate is (1-4):1, preferably (2-3):

1.

4. The heat-adhesive pressure-sensitive adhesive composition according to claim 1, wherein: The alkaline amine compound includes at least one of dipropylamine and cyclohexylamine.

5. The heat-adhesive pressure-sensitive adhesive composition according to claim 1, wherein: The preparation method of the double-end vinyl-terminated isocyanate is as follows: Compound 1 is added into a reaction container, an antioxidant and a first catalyst are added and mixed evenly, an inert gas is introduced, and Compound 2 is added to react, thereby obtaining the double-end vinyl-terminated isocyanate; Wherein, the structural formula of the compound 1 is shown in the following formula (1) or the following formula (2), and the structural formula of the compound 2 is shown in the following formula (3): Wherein, n is an integer between 4 and 10; Wherein, p is an integer between 1 and 4; Here, R1 is a hydrogen atom or a methyl group, and m is an integer between 1 and 4.

6. The heat-adhesive pressure-sensitive adhesive composition according to claim 5, wherein: The molar ratio of the compound 1 to the compound 2 is 1:

1.

7. The heat-adhesive pressure-sensitive adhesive composition according to claim 1, wherein: Taking the total amount of the constituent monomers of the acrylic ester copolymer as 100 wt %, the acrylic ester copolymer comprises the following monomer components: 5 to 15 wt % of hard monomers and 85 to 95 wt % of soft monomers; Wherein, the hard monomer includes at least one of methyl (meth)acrylate, styrene, acrylic acid, vinyl acetate, ethyl methacrylate, isobutyl methacrylate, acrylonitrile, cyclohexyl methacrylate, and isobornyl methacrylate; And / or, the soft monomer includes at least one of butyl acrylate, isooctyl acrylate, ethyl acrylate, n-octyl acrylate, and lauryl (meth)acrylate.

8. The heat-tackifying pressure-sensitive adhesive composition according to any one of claims 1 to 7, wherein: The heat-adhesive pressure-sensitive adhesive composition further includes a second initiator, a second catalyst and a cross-linking monomer; Preferably, relative to 100 parts by weight of the acrylic ester copolymer, the content of the second initiator is 0.01 to 0.8 parts by weight, the content of the second catalyst is 0.1 to 1 parts by weight, and the content of the cross-linking monomer is 0 to 3 parts by weight.

9. The heat-adhesive pressure-sensitive adhesive composition according to claim 8, wherein: The second initiator comprises at least one of benzoin and its derivatives, benzil derivatives, acetophenone derivatives, α-hydroxyalkyl phenones, α-amino ketone derivatives, and acylphosphine oxides; And / or, the second catalyst comprises at least one of dibutyltin dilaurate and dibutyltin diacetate; And / or, the cross-linking monomer includes at least one of 1,6-hexanediol diacrylate and polyurethane acrylate.

10. A pressure-sensitive adhesive, characterized in that: The pressure-sensitive adhesive comprises the heat-tackifying pressure-sensitive adhesive composition according to any one of claims 1 to 9.

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