Flame retardant pressure-sensitive adhesive, preparation method thereof and pressure-sensitive adhesive tape

Abstract

The present invention relates to the technical field of pressure-sensitive adhesives, and in particular to a flame-retardant pressure-sensitive adhesive, a preparation method thereof, and a pressure-sensitive adhesive tape. The flame-retardant pressure-sensitive adhesive comprises 90 to 99 parts of a modified acrylic resin, 1 to 10 parts of a cross-linking agent, and 0.1 to 2 parts of a first photoinitiator; the modified acrylic resin comprises 80 to 95 parts of an acrylic monomer, 5 to 20 parts of a phosphorus-containing acrylate monomer, 0.01 to 2 parts of a chain transfer agent, and 0.1 to 2 parts of a second photoinitiator; in the acrylic monomer, long-chain acrylates with carbon numbers of 15 to 22 account for 2% to 10%; the phosphorus-containing acrylate monomer comprises at least one of diethyl methyl phosphonate of methacrylate, diethyl methyl phosphonate of acrylate, diethyl ethyl phosphonate of methacrylate, and diethyl ethyl phosphonate of acrylate. The present invention adopts a phosphorus-containing acrylate monomer to be grafted onto an acrylic resin, and regulates the main composition of the acrylic resin, thereby improving the flame retardant properties and the bonding properties of the pressure-sensitive adhesive.

Description

Technical Field

[0001] The invention relates to the technical field of pressure-sensitive adhesives, in particular to a flame-retardant pressure-sensitive adhesive and a preparation method thereof and a pressure-sensitive adhesive tape. Background Art

[0002] In recent years, pressure-sensitive adhesives have begun to be used in various fields. In the electrical field, pressure-sensitive tapes need to have flame retardant effects in addition to insulation. Traditional electrical tapes are flame-retardant PVC tapes. In order to ensure flame retardancy, sufficient flame retardant additives need to be added. However, the use of too many flame retardant additives will affect the electrical breakdown strength, and combustion will cause serious environmental pollution. In recent years, researchers have been committed to developing flame-retardant pressure-sensitive adhesives, mainly by adding flame retardants to the pressure-sensitive adhesive system without participating in the reaction. However, this method not only affects the performance of the pressure-sensitive adhesive, but also limits the amount of addition, resulting in insufficient flame retardancy, and precipitation problems will occur during use.

[0003] In view of this, the present invention is proposed. Summary of the invention

[0004] An object of the present invention is to provide a flame retardant pressure sensitive adhesive having excellent flame retardant properties and bonding properties.

[0005] Another object of the present invention is to provide a method for preparing a flame retardant pressure sensitive adhesive.

[0006] Another object of the present invention is to provide a pressure-sensitive adhesive tape.

[0007] In order to achieve the above-mentioned object of the present invention, the present invention provides a flame retardant pressure-sensitive adhesive, comprising the following components in parts by weight: 90 to 99 parts of a modified acrylic resin, 1 to 10 parts of a cross-linking agent, and 0.1 to 2 parts of a first photoinitiator;

[0008] The modified acrylic resin comprises the following components by weight: 80-95 parts of acrylic monomer, 5-20 parts of phosphorus-containing acrylate monomer, 0.01-2 parts of chain transfer agent and 0.1-2 parts of second photoinitiator;

[0009] In the acrylic monomer, the proportion of long-chain acrylic acid esters with carbon numbers of 15 to 22 is 2 wt% to 10 wt%;

[0010] The phosphorus-containing acrylate monomer includes at least one of diethyl methylphosphonate methacrylate, diethyl methylphosphonate acrylate, diethyl ethylphosphonate methacrylate, and diethyl ethylphosphonate acrylate.

[0011] In a specific embodiment of the present invention, the long-chain acrylate with a carbon number of 15 to 22 includes at least one of lauryl acrylate, tetradecyl acrylate, hexadecyl acrylate and octadecyl acrylate. Further, the long-chain acrylate with a carbon number of 15 to 22 is hexadecyl acrylate and / or octadecyl acrylate.

[0012] In a specific embodiment of the present invention, the acrylic monomer also includes at least one of isooctyl acrylate, ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, methyl methacrylate, methyl acrylate, acrylic acid, hydroxyethyl acrylate, hydroxypropyl acrylate, isobutyl acrylate and 2-phenoxyethyl acrylate.

[0013] In a specific embodiment of the present invention, the mass ratio of the long-chain acrylate to the phosphorus-containing acrylate monomer is 1:(2-5).

[0014] In a specific embodiment of the present invention, the preparation of the modified acrylic resin includes: after uniformly mixing acrylic monomer, phosphorus-containing acrylate monomer, chain transfer agent and second photoinitiator, reacting under ultraviolet light until the viscosity reaches 2000-3000 cps.

[0015] In a specific embodiment of the present invention, the crosslinking agent includes at least one of 1,6-hexanediol diacrylate, polyethylene glycol diacrylate, 1,4-cyclohexanedimethanol monoacrylate, ethylene glycol dimethacrylate, cyclohexanedimethanol diacrylate, pentaerythritol triacrylate, tris(2-hydroxyethyl)isocyanuric acid triacrylate, trimethylolpropane triacrylate, ditrimethylolpropane acrylate and dipentaerythritol hexaacrylate.

[0016] In a specific embodiment of the present invention, the first photoinitiator and the second photoinitiator are each independently selected from at least one of photoinitiator TPO, photoinitiator 184 and photoinitiator 1173.

[0017] In a specific embodiment of the present invention, the chain transfer agent includes at least one of ethyl mercaptan, butyl mercaptan, dodecyl mercaptan and benzene mercaptan.

[0018] Another aspect of the present invention provides a method for preparing any one of the flame retardant pressure sensitive adhesives described above, comprising the following steps: mixing the components in proportion, and then ultraviolet curing to form the mixture.

[0019] Another aspect of the present invention provides a pressure-sensitive adhesive tape, comprising any one of the flame-retardant pressure-sensitive adhesives described above.

[0020] Compared with the prior art, the present invention has the following beneficial effects:

[0021] (1) The present invention adopts phosphorus-containing acrylate monomers to be grafted onto acrylic resin, and at the same time, the main composition of the acrylate resin is adjusted to improve the flame retardant properties of the pressure-sensitive adhesive while improving the bonding properties of the pressure-sensitive adhesive and ensuring that no precipitation occurs during use;

[0022] (2) The flame retardant pressure-sensitive adhesive of the present invention can reach the UL94 V-0 level, while improving the initial adhesion, lasting adhesion and peel strength, thus meeting the use requirements of pressure-sensitive adhesives in the electrical engineering field. DETAILED DESCRIPTION

[0023] The technical scheme of the present invention will be clearly and completely described below in conjunction with specific embodiments, but it will be appreciated by those skilled in the art that the following described embodiments are part of embodiments of the present invention, rather than all embodiments, and are only used to illustrate the present invention, and should not be considered as limiting the scope of the present invention. Based on the embodiments in the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative work, all belong to the scope of protection of the present invention. If specific conditions are not indicated in the embodiments, they are carried out according to normal conditions or conditions recommended by the manufacturer. If the manufacturer is not indicated in the reagents or instruments used, they are all conventional products that can be purchased commercially.

[0024] By introducing the flame retardant into the acrylic resin by chemical grafting, the compatibility of the flame retardant and the acrylic resin can be improved, and the problems such as precipitation can be avoided. However, the inventors of the present invention have found in the study that although the flame retardant is chemically grafted to the acrylic resin, the compatibility of the flame retardant and the acrylic resin can be improved to a certain extent, if the required flame retardant level is to be achieved, a flame retardant with a high phosphorus content is required, or an additional compounded additive flame retardant is required. For high-phosphorus content flame retardants, the carbon chain length in the flame retardant is usually relatively short, and it contains a certain phosphate group. Excessive introduction will lead to insufficient initial adhesion of the pressure-sensitive adhesive; the method of compounding additive flame retardants cannot fundamentally solve the problem of precipitation. If a flame retardant with a low phosphorus content is used to replace a flame retardant with a high phosphorus content, a higher amount of addition is required to achieve the required flame retardant level, which will lead to insufficient cohesive strength of the pressure-sensitive adhesive. Therefore, it is of great significance to develop a flame-retardant pressure-sensitive adhesive that can ensure flame retardant properties and avoid precipitation, and has excellent initial adhesion, sustained adhesion and peel strength.

[0025] Based on this, the present invention provides a flame retardant pressure-sensitive adhesive, comprising the following components in parts by weight: 90 to 99 parts of a modified acrylic resin, 1 to 10 parts of a cross-linking agent, and 0.1 to 2 parts of a first photoinitiator;

[0026] The modified acrylic resin comprises the following components by weight: 80-95 parts of acrylic monomer, 5-20 parts of phosphorus-containing acrylate monomer, 0.01-2 parts of chain transfer agent and 0.1-2 parts of second photoinitiator;

[0027] Among acrylic monomers, long-chain acrylates with carbon numbers of 15 to 22 account for 2 wt% to 10 wt%;

[0028] The phosphorus-containing acrylate monomer includes at least one of diethyl methylphosphonate methacrylate, diethyl methylphosphonate acrylate, diethyl ethylphosphonate methacrylate, and diethyl ethylphosphonate acrylate.

[0029] The present invention uses a flame retardant with a relatively high phosphorus content to modify the acrylic resin, and within a certain range of addition, the V-0 level can be achieved. At the same time, the types of acrylic monomers in the acrylic resin are regulated so that the proportion of long-chain acrylates in the acrylic resin meets a preset range. On the one hand, the introduction of long side chains is used to improve the wetting and adhesion properties of the adhered surface. On the other hand, some long side chains are stacked and crystallized in the system, which can improve the cohesive force and effectively improve the initial adhesion, sustained adhesion and peel strength of the flame-retardant pressure-sensitive adhesive.

[0030] In the modified acrylic resin of the present invention, the amounts of the components in parts by weight can be as follows:

[0031] The amount of acrylic monomer can be 80 parts, 82 parts, 85 parts, 88 parts, 90 parts, 92 parts, 95 parts or a range consisting of any two of them;

[0032] The amount of the phosphorus-containing acrylate monomer can be 5 parts, 8 parts, 10 parts, 12 parts, 15 parts, 18 parts, 20 parts or a range consisting of any two of them;

[0033] The amount of the chain transfer agent can be 0.01 part, 0.1 part, 0.5 part, 1 part, 1.5 parts, 2 parts or any two thereof;

[0034] The amount of the second photoinitiator can be 0.1 parts, 0.5 parts, 1 parts, 1.5 parts, 2 parts or a range consisting of any two of them.

[0035] The phosphorus-containing acrylate monomer of the present invention comprises at least one of diethyl methylphosphonate of methacrylate, diethyl methylphosphonate of acrylate, diethyl ethylphosphonate of methacrylate and diethyl ethylphosphonate of acrylate, and the specific structures are as follows:

[0036]

[0037] The phosphorus content of each phosphorus-containing acrylate monomer is above 10%, and the side chain length is appropriate. By using these phosphorus-containing acrylate monomers, within the above-mentioned phosphorus-containing acrylate monomer dosage range, and combining with acrylic monomers to prepare modified acrylic resin, a flame-retardant pressure-sensitive adhesive that meets the V-0 level can be obtained.

[0038] While introducing the above-mentioned phosphorus-containing acrylate monomer, the type of acrylic monomer for preparing acrylic resin is regulated, and a certain amount of long-chain acrylate with a carbon number of 15 to 22 is introduced. The long side chain is used to improve the wetting and adhesion ability of the viscosity surface. At the same time, some long side chains are stacked and crystallized in the system to improve the cohesive force, thereby taking into account the improvement of the initial adhesion, sustained adhesion and peel strength of the pressure-sensitive adhesive. For example, in different embodiments, in the acrylic monomer, the proportion of long-chain acrylate with a carbon number of 15 to 22 can be 2wt%, 3wt%, 4wt%, 5wt%, 6wt%, 7wt%, 8wt%, 9wt%, 10wt% or any two thereof. It is found that in the pressure-sensitive adhesive system of the present invention, when the proportion of long-chain acrylate is too low, the improvement of initial adhesion and cohesive strength is not obvious; when the proportion of long-chain acrylate is too high, the proportion of stacking crystallization behavior of the long side chain is too high, resulting in a significant decrease in initial adhesion. By regulating the content of long-chain acrylate within the above range and introducing a certain amount of acrylate monomer, the flame retardant properties can be ensured while improving the initial adhesion, lasting adhesion and peel strength.

[0039] Furthermore, the carbon number of the long-chain acrylate can be 15, 16, 17, 18, 19, 20, 21, 22 or a combination of at least two thereof. Studies have found that when the carbon number of the long-chain acrylate is too low, that is, the chain length is short, the stacking crystallization of the side chain is not obvious, and the holding viscosity and peel strength cannot be effectively improved; when the carbon number of the long-chain acrylate is too high, the stacking crystallization of the side chain is too significant, the viscosity of the system is uncontrollable, and the initial adhesion cannot be improved. By using a long-chain acrylate with a carbon number that meets the above requirements and matching its dosage range, some of the long side chains in the system are stacked and crystallized to improve the cohesive strength, while the remaining long side chains fully wet the adhered surface to improve the initial adhesion.

[0040] In the flame retardant pressure sensitive adhesive of the present invention, the amounts of the components in parts by weight can be as follows:

[0041] The amount of the modified acrylic resin can be 90 parts, 92 parts, 95 parts, 98 parts, 99 parts or a range consisting of any two of them;

[0042] The amount of the cross-linking agent can be 1 part, 2 parts, 5 parts, 8 parts, 10 parts or a range consisting of any two of them;

[0043] The amount of the first photoinitiator can be 0.1 parts, 0.5 parts, 1 parts, 1.5 parts, 2 parts or a range consisting of any two of them.

[0044] In a specific embodiment of the present invention, the long-chain acrylate with a carbon number of 15 to 22 includes at least one of lauryl acrylate, tetradecyl acrylate, hexadecyl acrylate and octadecyl acrylate. Further, the long-chain acrylate with a carbon number of 15 to 22 is hexadecyl acrylate and / or octadecyl acrylate.

[0045] In a specific embodiment of the present invention, the acrylic monomer also includes at least one of isooctyl acrylate, ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, methyl methacrylate, methyl acrylate, acrylic acid, hydroxyethyl acrylate, hydroxypropyl acrylate, isobutyl acrylate and 2-phenoxyethyl acrylate.

[0046] In a specific embodiment of the present invention, the acrylic monomer further comprises isooctyl acrylate, hydroxyethyl acrylate and methyl acrylate. Further, the acrylic monomer comprises the following components by mass percentage: 2% to 10% long-chain acrylate, 35% to 60% isooctyl acrylate, 15% to 30% hydroxyethyl acrylate and 10% to 25% methyl acrylate.

[0047] For example, in different embodiments, in the acrylic monomer, the amount of some materials used can be as follows, calculated by mass percentage:

[0048] The amount of isooctyl acrylate can be 35%, 40%, 45%, 50%, 55%, 60% or a range consisting of any two thereof;

[0049] The amount of hydroxyethyl acrylate can be 15%, 18%, 20%, 22%, 25%, 28%, 30% or any two thereof; wherein hydroxyethyl acrylate can be partially or completely replaced by hydroxypropyl acrylate, etc.;

[0050] The amount of methyl acrylate can be 10%, 12%, 15%, 18%, 20%, 22%, 25% or a range consisting of any two thereof.

[0051] In a specific embodiment of the present invention, the mass ratio of the long-chain acrylate to the phosphorus-containing acrylate monomer is 1:(2-5), preferably 1:(2-3).

[0052] Phosphorus-containing acrylate monomers can cause the initial adhesion of pressure-sensitive adhesives to decrease, and long-chain acrylates can be compounded to improve initial adhesion and peel strength. The present invention further found that the ratio of the amount of long-chain acrylate to phosphorus-containing acrylate monomers within the above range is more conducive to giving full play to the improvement of the initial adhesion of the pressure-sensitive adhesive system by long-chain acrylates, and can also significantly improve the lasting adhesion and peel strength. For example, in different embodiments, the mass ratio of long-chain acrylate to phosphorus-containing acrylate monomers can be 1:2, 1:2.5, 1:3, 1:3.5, 1:4, 1:4.5, 1:5, or a range consisting of any two of them.

[0053] In a specific embodiment of the present invention, the preparation of the modified acrylic resin includes: mixing acrylic monomer, phosphorus-containing acrylate monomer, chain transfer agent and second photoinitiator uniformly, and reacting under ultraviolet light until the viscosity reaches 2000-3000 cps.

[0054] The viscosity of the modified acrylic resin is within the above range, which can ensure the uniformity of mixing with other components and ensure that the system has a certain fluidity; on the other hand, it can regulate the degree of reaction so that the system is fully cured when preparing the pressure-sensitive adhesive to ensure cohesive strength, etc.

[0055] In actual operation, the preparation of modified acrylic resin is carried out under a protective atmosphere. For example, the uniformly mixed materials can be filled with nitrogen and then subjected to ultraviolet irradiation reaction under a nitrogen protective atmosphere.

[0056] In a specific embodiment of the present invention, the crosslinking agent includes at least one of 1,6-hexanediol diacrylate, polyethylene glycol diacrylate, 1,4-cyclohexanedimethanol monoacrylate, ethylene glycol dimethacrylate, cyclohexanedimethanol diacrylate, pentaerythritol triacrylate, tris(2-hydroxyethyl)isocyanuric acid triacrylate, trimethylolpropane triacrylate, ditrimethylolpropane acrylate and dipentaerythritol hexaacrylate.

[0057] In a specific embodiment of the present invention, the first photoinitiator and the second photoinitiator are each independently selected from at least one of photoinitiator TPO, photoinitiator 184 and photoinitiator 1173.

[0058] In a specific embodiment of the present invention, the chain transfer agent includes at least one of ethyl mercaptan, butyl mercaptan, dodecyl mercaptan and benzene mercaptan.

[0059] In a specific embodiment of the present invention, the flame retardant pressure sensitive adhesive shows a V-0 grade in the UL-94 vertical flame retardancy test.

[0060] Another aspect of the present invention provides a method for preparing any one of the flame retardant pressure sensitive adhesives mentioned above, comprising the following steps: mixing the components in proportion, and then ultraviolet curing to form the mixture.

[0061] In actual operation, the preparation of the flame retardant pressure sensitive adhesive may include: coating the mixed materials into a film, and then UV curing. The flame retardant pressure sensitive adhesive is in the form of a film, and the thickness can be 25 to 100 μm, and the thickness can be adjusted according to actual needs.

[0062] In a specific embodiment of the present invention, during UV curing, the UV wavelength is 200-400 nm, and the UV energy is 600-1000 mj / cm 2 For example, a high pressure mercury lamp may be used, but is not limited thereto, as long as it can initiate polymerization.

[0063] Another aspect of the present invention provides a pressure-sensitive adhesive tape, comprising any one of the above-mentioned flame-retardant pressure-sensitive adhesives.

[0064] In the preparation of the pressure-sensitive adhesive tape, the flame-retardant pressure-sensitive adhesive (not UV-cured) can be coated on the surface of the substrate, then covered with a release film, and then UV-cured to obtain the tape.

[0065] Example 1

[0066] This embodiment provides a method for preparing a flame retardant pressure sensitive adhesive, comprising the following steps:

[0067] (1) Take 50 parts by weight of isooctyl acrylate, 20 parts by weight of hydroxyethyl acrylate, 15 parts by weight of methyl acrylate, 5 parts by weight of octadecyl acrylate, 15 parts by weight of diethyl methylphosphonate methacrylate, 0.1 parts by weight of dodecyl mercaptan and 1 part by weight of photoinitiator TPO, mix them evenly, fill with nitrogen for 20 minutes and start polymerization by irradiation with a mercury lamp under nitrogen protection. When the viscosity of the reaction system reaches about 2500 cps, terminate the reaction to obtain a modified acrylic resin.

[0068] (2) Take 98 parts of the modified acrylic resin prepared in step (1), 2 parts of 1,6-hexanediol diacrylate and 0.2 parts of photoinitiator TPO, and mix them evenly. Then, apply them on a PVC substrate to form a film, cover it with a PET release film, and cure it under a mercury lamp for 3 minutes to obtain a flame retardant pressure-sensitive adhesive tape with a pressure-sensitive adhesive thickness of 25 μm.

[0069] Example 2

[0070] This embodiment refers to the method for preparing the flame retardant pressure sensitive adhesive of Embodiment 1, with the only difference being that step (1) is different.

[0071] Step (1) of this embodiment comprises: taking 48 parts of isooctyl acrylate, 19 parts of hydroxyethyl acrylate, 14 parts of methyl acrylate, 9 parts of octadecyl acrylate, 15 parts of diethyl methylphosphonate methacrylate, 0.1 parts of dodecyl mercaptan and 1 part of photoinitiator TPO, by weight, mixing them evenly, filling with nitrogen for 20 minutes and irradiating with a mercury lamp under nitrogen protection to start polymerization. When the viscosity of the reaction system reaches about 2500 cps, the reaction is terminated to obtain a modified acrylic resin.

[0072] Example 3

[0073] This embodiment refers to the method for preparing the flame retardant pressure sensitive adhesive of Embodiment 1, with the only difference being that step (1) is different.

[0074] Step (1) of this embodiment comprises: taking 52 parts of isooctyl acrylate, 20.5 parts of hydroxyethyl acrylate, 15.5 parts of methyl acrylate, 2 parts of octadecyl acrylate, 15 parts of diethyl methylphosphonate methacrylate, 0.1 parts of dodecyl mercaptan and 1 part of photoinitiator TPO, by weight, mixing them evenly, filling with nitrogen for 20 minutes and irradiating with a mercury lamp under nitrogen protection to start polymerization. When the viscosity of the reaction system reaches about 2500 cps, the reaction is terminated to obtain a modified acrylic resin.

[0075] Example 4

[0076] This embodiment refers to the method for preparing the flame retardant pressure-sensitive adhesive of Embodiment 1, with the only difference being that in step (1), the amount of phosphorus-containing acrylate monomer used is different.

[0077] In this embodiment, the usage of diethyl methyl phosphonate of methacrylate is 5 parts.

[0078] Example 5

[0079] This embodiment refers to the method for preparing the flame retardant pressure-sensitive adhesive of Embodiment 1, with the only difference being that in step (1), the amount of phosphorus-containing acrylate monomer used is different.

[0080] In this embodiment, the usage of diethyl methyl phosphonate of methacrylate is 20 parts.

[0081] Example 6

[0082] This embodiment refers to the method for preparing the flame retardant pressure-sensitive adhesive of Embodiment 1, with the only difference being that in step (1), the amount of phosphorus-containing acrylate monomer used is different.

[0083] In this embodiment, the usage of diethyl methyl phosphonate of methacrylate is 10 parts.

[0084] Example 7

[0085] This embodiment refers to the method for preparing the flame retardant pressure-sensitive adhesive of Embodiment 1, with the only difference being that in step (1), the type of phosphorus-containing acrylate monomer is different.

[0086] In this embodiment, the phosphorus-containing acrylate monomer is diethyl ethyl phosphonate.

[0087] Example 8

[0088] This embodiment refers to the method for preparing the flame retardant pressure-sensitive adhesive of Embodiment 1, with the only difference being that in step (1), the type of long-chain acrylate is different.

[0089] In this embodiment, the long-chain acrylate is hexadecyl acrylate.

[0090] Example 9

[0091] This embodiment refers to the method for preparing the flame retardant pressure-sensitive adhesive of Embodiment 1, with the only difference being that in step (1), the type of long-chain acrylate is different.

[0092] In this embodiment, the long-chain acrylate is lauryl acrylate.

[0093] Comparative Example 1

[0094] Comparative Example 1 refers to the method for preparing the flame retardant pressure-sensitive adhesive of Example 1, except that: step (1) is different.

[0095] Step (1) of Comparative Example 1 comprises: taking 53 parts of isooctyl acrylate, 21 parts of hydroxyethyl acrylate, 16 parts of methyl acrylate, 15 parts of diethyl methylphosphonate methacrylate, 0.1 parts of dodecyl mercaptan and 1 part of photoinitiator TPO, by weight, mixing them evenly, filling with nitrogen for 20 minutes and irradiating with a mercury lamp under nitrogen protection to start polymerization, and terminating the reaction when the viscosity of the reaction system reaches about 2500 cps to obtain a modified acrylic resin.

[0096] Comparative Example 2

[0097] Comparative Example 2 refers to the method for preparing the flame retardant pressure sensitive adhesive of Example 1, except that: step (1) is different.

[0098] Step (1) of Comparative Example 2 comprises: taking 52 parts of isooctyl acrylate, 21 parts of hydroxyethyl acrylate, 16 parts of methyl acrylate, 1 part of octadecyl acrylate, 15 parts of diethyl methylphosphonate methacrylate, 0.1 parts of dodecyl mercaptan and 1 part of photoinitiator TPO, by weight, mixing them evenly, filling with nitrogen for 20 minutes and irradiating with a mercury lamp under nitrogen protection to start polymerization, and terminating the reaction when the viscosity of the reaction system reaches about 2500 cps to obtain a modified acrylic resin.

[0099] Comparative Example 3

[0100] Comparative Example 3 refers to the method for preparing the flame retardant pressure sensitive adhesive of Example 1, except that: step (1) is different.

[0101] Step (1) of Comparative Example 3 comprises: taking, by weight, 47 parts of isooctyl acrylate, 19 parts of hydroxyethyl acrylate, 14 parts of methyl acrylate, 10 parts of octadecyl acrylate, 15 parts of diethyl methylphosphonate methacrylate, 0.1 parts of dodecyl mercaptan and 1 part of photoinitiator TPO, mixing them evenly, filling with nitrogen for 20 minutes and irradiating with a mercury lamp under nitrogen protection to start polymerization, and terminating the reaction when the viscosity of the reaction system reaches about 2500 cps to obtain a modified acrylic resin.

[0102] Comparative Example 4

[0103] Comparative Example 4 refers to the method for preparing the flame retardant pressure-sensitive adhesive of Example 1, except that in step (1), the amount of phosphorus-containing acrylate monomer used is different.

[0104] In Comparative Example 4, the amount of diethyl methyl phosphonate of methacrylate was 3 parts.

[0105] Comparative Example 5

[0106] Comparative Example 5 refers to the method for preparing the flame retardant pressure-sensitive adhesive of Example 1, except that in step (1), the amount of phosphorus-containing acrylate monomer used is different.

[0107] In Comparative Example 5, the amount of diethyl methyl phosphonate of methacrylate was 25 parts.

[0108] Comparative Example 6

[0109] Comparative Example 6 refers to the method for preparing the flame retardant pressure-sensitive adhesive of Example 1, except that in step (1), the type of long-chain acrylate is different.

[0110] In Comparative Example 6, decyl acrylate was used in an equal weight amount to replace octadecyl acrylate.

[0111] Comparative Example 7

[0112] Comparative Example 7 refers to the method for preparing a flame retardant pressure-sensitive adhesive of Example 1, except that in step (1), the type of phosphorus-containing acrylate monomer is different.

[0113] In Comparative Example 7, an equal weight of dimethyl vinyl phosphate was used to replace diethyl methyl methacrylate.

[0114] Experimental example

[0115] In order to compare and illustrate the performance differences of the flame retardant pressure sensitive adhesives of different embodiments and comparative examples, the following tests were conducted respectively. The test results are shown in Table 1.

[0116] Initial adhesion: refer to GB / T 4852-2002, measuring angle is 30°;

[0117] Adhesion retention: refer to GB / T 4851-2014;

[0118] 180° peel strength: refer to GB / T 2792-2014, peel speed is 300mm / min;

[0119] Flame retardant grade: tested on a horizontal and vertical combustion apparatus in accordance with UL94-2023 standard.

[0120] Table 1 Performance test results of different pressure-sensitive adhesives

[0121]

[0122] From the above test results, it can be seen that the present invention adopts phosphorus-containing acrylate monomers to be grafted onto acrylic resin, and at the same time, the main composition of the acrylate resin is regulated, so as to improve the flame retardant properties of the pressure-sensitive adhesive while improving the bonding properties of the pressure-sensitive adhesive and ensuring that no precipitation occurs during use.

[0123] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein by equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. Flame retardant pressure sensitive adhesive, characterized in that: The invention comprises the following components in parts by weight: 90 to 99 parts of modified acrylic resin, 1 to 10 parts of crosslinking agent and 0.1 to 2 parts of first photoinitiator; The modified acrylic resin comprises the following components by weight: 80-95 parts of acrylic monomer, 5-20 parts of phosphorus-containing acrylate monomer, 0.01-2 parts of chain transfer agent and 0.1-2 parts of second photoinitiator; In the acrylic monomer, the proportion of long-chain acrylic acid esters with carbon numbers of 15 to 22 is 2 wt% to 10 wt%; The phosphorus-containing acrylate monomer includes at least one of diethyl methylphosphonate methacrylate, diethyl methylphosphonate acrylate, diethyl ethylphosphonate methacrylate, and diethyl ethylphosphonate acrylate.

2. The flame retardant pressure sensitive adhesive according to claim 1, characterized in that: The long-chain acrylic acid ester having a carbon number of 15 to 22 includes at least one of lauryl acrylate, tetradecyl acrylate, hexadecyl acrylate and octadecyl acrylate.

3. The flame retardant pressure sensitive adhesive according to claim 1, characterized in that: The acrylic monomer further includes at least one of isooctyl acrylate, ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, methyl methacrylate, methyl acrylate, acrylic acid, hydroxyethyl acrylate, hydroxypropyl acrylate, isobutyl acrylate and 2-phenoxyethyl acrylate.

4. The flame retardant pressure sensitive adhesive according to claim 1, characterized in that: The mass ratio of the long-chain acrylate to the phosphorus-containing acrylate monomer is 1:(2-5).

5. The flame retardant pressure sensitive adhesive according to claim 1, characterized in that: The preparation of the modified acrylic resin includes: uniformly mixing the acrylic monomer, the phosphorus-containing acrylate monomer, the chain transfer agent and the second photoinitiator, and reacting them under ultraviolet light until the viscosity reaches 2000-3000 cps.

6. The flame retardant pressure sensitive adhesive according to claim 1, characterized in that: The crosslinking agent includes at least one of 1,6-hexanediol diacrylate, polyethylene glycol diacrylate, ethylene glycol dimethacrylate, cyclohexanedimethanol diacrylate, pentaerythritol triacrylate, tris(2-hydroxyethyl)isocyanuric acid triacrylate, trimethylolpropane triacrylate, ditrimethylolpropane acrylate and dipentaerythritol hexaacrylate.

7. The flame retardant pressure sensitive adhesive according to claim 1, characterized in that: The first photoinitiator and the second photoinitiator are each independently selected from at least one of photoinitiator TPO, photoinitiator 184 and photoinitiator 1173.

8. The flame retardant pressure sensitive adhesive according to claim 1, characterized in that: The chain transfer agent includes at least one of ethyl mercaptan, butyl mercaptan, dodecyl mercaptan and benzene mercaptan.

9. The method for preparing the flame retardant pressure sensitive adhesive according to any one of claims 1 to 8, characterized in that: The method comprises the following steps: mixing the components in proportion and then subjecting the components to ultraviolet curing for forming.

10. A pressure-sensitive adhesive tape, characterized in that: The invention comprises the flame retardant pressure sensitive adhesive according to any one of claims 1 to 8 or the flame retardant pressure sensitive adhesive prepared by the preparation method according to claim 9.

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