Acrylic pressure-sensitive adhesive for TPU car cover film and preparation method thereof

Abstract

The present invention discloses an acrylate pressure-sensitive adhesive for TPU car cover film and a preparation method thereof in the field of pressure-sensitive adhesive technology. The acrylate pressure-sensitive adhesive for TPU car cover film includes the following raw materials in weight percentage: soft monomer: 20-25%, hard monomer: 8-12%, functional monomer: 2-4%, adhesion promoting monomer: 0.2-1%, reactive polycaprolactone: 0.5-2%, initiator: 0.05-0.2%, solvent: 55-68%, curing agent: 0.15-0.5%. The present invention introduces reactive polycaprolactone to improve the adhesive force of the acrylate pressure-sensitive adhesive and improve the mobility. Adhesion promoting monomers are introduced to improve the peeling force of the acrylate pressure-sensitive adhesive. At the same time, the synthesis method of the acrylate pressure-sensitive adhesive adopts a pure dropwise reaction method of dropping monomers at the solvent reflux temperature, the reaction temperature is easy to control, the upper kettle production is easier to implement, and there is no risk of temperature and material rushing.

Description

Technical Field

[0001] The invention relates to the technical field of pressure-sensitive adhesives, in particular to an acrylic pressure-sensitive adhesive for a TPU car cover film and a preparation method thereof. Background Art

[0002] TPU car cover film, also known as TPU paint protection film, is a high-performance thermoplastic polyurethane film that is widely used in the car film beauty and maintenance industry. It is also the preferred material for high-end paint protection films, which protects the paint surface and enhances the paint brightness. TPU car cover film materials are divided into aromatic TPU and aliphatic TPU. In order to prevent yellowing, TPU car cover films use aliphatic TPU. Aliphatic TPU is divided into polyester type, polyether type and polycaprolactone type. Among them, polycaprolactone TPU has better high temperature resistance and hydrolysis resistance, so it once surpassed several other materials and became the high-end and high-quality TPU car cover film material on the market.

[0003] TPU car cover film needs to be attached to the car paint surface by adhesive. Acrylic pressure-sensitive adhesive is widely used as glue for TPU car cover film due to its advantages such as low cost, easy bonding and convenient construction. However, the surface energy of TPU car cover film material is low, which places high requirements on the acrylic pressure-sensitive adhesive used for bonding. It is difficult to achieve good adhesion using conventional acrylic pressure-sensitive adhesive, which leads to poor removability of TPU car cover film, residual debonding and other problems. In severe cases, it will damage the surface of the car paint and greatly affect the use effect. At the same time, in order to meet the construction requirements of quick pasting of TPU car cover film and shorten the time of pasting, acrylic pressure-sensitive adhesive is required to have a high initial peeling force, while the conventional acrylic pressure-sensitive adhesive on the market has relatively low viscosity and is difficult to meet the requirements of quick pasting construction. Summary of the invention

[0004] The purpose of this section is to summarize some aspects of the embodiments of the present invention and briefly introduce some preferred embodiments. Some simplifications or omissions may be made in this section and the specification abstract and the invention title of this application to avoid blurring the purpose of this section, the specification abstract and the invention title, and such simplifications or omissions cannot be used to limit the scope of the present invention.

[0005] Therefore, the object of the present invention is to provide an acrylic pressure-sensitive adhesive for TPU car cover film and a preparation method thereof, so as to solve the problems raised in the above background technology.

[0006] To solve the above technical problems, according to one aspect of the present invention, the present invention provides the following technical solutions:

[0007] An acrylic pressure-sensitive adhesive for a TPU car cover film comprises the following raw materials in percentage by weight: soft monomer: 20-25%, hard monomer: 8-12%, functional monomer: 2-4%, adhesion promoting monomer: 0.2-1%, reactive polycaprolactone: 0.5-2%, initiator: 0.05-0.2%, solvent: 55-68%, and curing agent: 0.15-0.5%.

[0008] As a preferred embodiment of the acrylic pressure-sensitive adhesive for TPU car cover film described in the present invention, the soft monomer is one or more of isooctyl acrylate, butyl acrylate, ethyl acrylate, and lauryl methacrylate.

[0009] As a preferred embodiment of the acrylic pressure-sensitive adhesive for TPU car cover film described in the present invention, the hard monomer is one or more of methyl acrylate, methyl methacrylate, butyl methacrylate, isobornyl acrylate, and vinyl acetate.

[0010] As a preferred embodiment of the acrylic pressure-sensitive adhesive for TPU car cover film described in the present invention, the functional monomer is one or more of acrylic acid, methacrylic acid, hydroxyethyl acrylate, hydroxypropyl acrylate, and glycidyl methacrylate.

[0011] As a preferred embodiment of the acrylic pressure-sensitive adhesive for TPU car cover film described in the present invention, the adhesion-promoting monomer is one or more of β-acryloxypropionic acid, acrylonitrile, and acrylamide.

[0012] As a preferred embodiment of the acrylic pressure-sensitive adhesive for TPU car cover film of the present invention, the specific structural formula of the reactive polycaprolactone is as follows:

[0013] .

[0014] A method for preparing an acrylic pressure-sensitive adhesive for a TPU car cover film, the specific steps are as follows:

[0015] S1, mixing all soft monomers, hard monomers, functional monomers, adhesion promoting monomers, reactive polycaprolactone, and a portion of initiators to obtain a mixed monomer;

[0016] S2, adding a portion of the solvent into the reaction vessel, heating to a temperature of 75-85°C, allowing the solvent to reflux stably, and then dripping the mixed monomer into the reaction vessel at the solvent reflux temperature for 2-4 hours. After the dripping of the mixed monomer is completed, the reaction is kept at the solvent reflux temperature for 2-4 hours;

[0017] S3, adding the remaining initiator into the reaction vessel three times after dissolving it with a portion of the solvent, and keeping the reaction at the reflux temperature of the solvent for 1-3 hours after each addition;

[0018] S4. After the reaction is completed, the temperature is lowered to below 50° C., and the remaining solvent and curing agent are added and stirred evenly to obtain the acrylic pressure-sensitive adhesive for TPU car cover film.

[0019] As a preferred embodiment of the method for preparing an acrylic pressure-sensitive adhesive for TPU car cover film according to the present invention, the amount of the initiator in step S1 accounts for 15-25% of the total amount of the initiator.

[0020] As a preferred embodiment of the method for preparing an acrylic pressure-sensitive adhesive for TPU car cover film according to the present invention, the proportion of the solvent used in step S2 to the total amount of the solvent is 60-75%.

[0021] As a preferred embodiment of the method for preparing an acrylic pressure-sensitive adhesive for TPU car cover film according to the present invention, in step S3, the mass ratio of the solvent for dissolving the initiator to the initiator is 1:0.02-0.06.

[0022] Compared with the prior art, the present invention has the following beneficial effects: the present invention improves the adhesive force of the acrylic pressure-sensitive adhesive and improves the mobility by introducing reactive polycaprolactone. The adhesive force-promoting monomer is introduced to improve the peeling force of the acrylic pressure-sensitive adhesive. At the same time, the synthesis method of the acrylic pressure-sensitive adhesive adopts a pure dropwise reaction method of dropping the monomer at the reflux temperature of the solvent, the reaction temperature is easy to control, the upper kettle production is easier to implement, and there is no risk of temperature and material shock. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the present invention will be described in detail below in combination with the accompanying drawings and detailed embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative labor. Among them:

[0024] Figure 1 This is a flow chart of a method for preparing an acrylic pressure-sensitive adhesive for TPU car cover film according to the present invention;

[0025] Figure 2 Schematic diagram of performance parameters of the polyurethane pressure-sensitive adhesive protective films prepared in Examples 1-4 of the present invention. DETAILED DESCRIPTION

[0026] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the specific embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0027] In order to illustrate the above scheme, the following Examples 1-4 are provided for verification. Example 1

[0028] S1. Add 52.6 g of isooctyl acrylate, 59.8 g of butyl acrylate, 39.1 g of methyl methacrylate, 13.7 g of vinyl acetate, 11.9 g of methacrylic acid, 0.17 g of hydroxyethyl acrylate, 1.8 g of β-CEA, 3.7 g of FA2D, and 0.1 g of azobisisobutyl cyanide into a 250 mL beaker, stir and mix well to obtain a mixed monomer;

[0029] S2. Add 206.8 g of ethyl acetate into a 1L four-necked flask equipped with a stirring paddle, a thermometer, and a reflux condenser, and heat it in a constant temperature water bath until the solvent refluxes stably (temperature 78°C). Add the mixed monomers evenly to the reaction bottle using a constant pressure dropping funnel at the solvent reflux temperature. The addition takes 2 hours. After the addition is completed, keep the reaction at the solvent reflux temperature for 2 hours.

[0030] S3, add the first initiator, dissolve 0.1g of azobisisobutyl cyanide with 3.7g of ethyl acetate and add it to the reaction bottle, keep the temperature at the reflux temperature for 1h. Add the second initiator, dissolve 0.22g of azobisisobutyl cyanide with 5.8g of ethyl acetate and add it to the reaction bottle, keep the temperature at the reflux temperature for 1h, add the third initiator, dissolve 0.1g of azobisisobutyl cyanide with 2.2g of ethyl acetate and add it to the reaction bottle, keep the temperature at the reflux temperature for 2h.

[0031] S4. After the reaction is completed, the temperature is lowered to below 50°C, and 43.4 g of isopropanol, 53.1 g of toluene, 0.37 g of aluminum acetylacetonate, and 1.1 g of acetylacetone are added and stirred evenly. Example 2

[0032] S1. Add 62.6 g of isooctyl acrylate, 48.8 g of butyl acrylate, 41 g of methyl acrylate, 11.8 g of vinyl acetate, 10.9 g of acrylic acid, 0.17 g of hydroxypropyl acrylate, 2.8 g of β-CEA, 4.7 g of FA2D, and 0.15 g of azobisisovaleronitrile into a 250 mL beaker, stir and mix well to obtain a mixed monomer;

[0033] S2. In a 1L four-necked flask equipped with a stirring paddle, a thermometer, and a reflux condenser, 180.9g of ethyl acetate and 25.8g of toluene were added, and heated in a constant temperature water bath until the solvent was stably refluxed (temperature 80°C). At the solvent reflux temperature, the mixed monomers were evenly added dropwise to the reaction bottle using a constant pressure dropping funnel. The addition took 2h. After the addition was completed, the mixture was kept at the solvent reflux temperature for 2h.

[0034] S3, add the first initiator, dissolve 0.13g of azobisisopentyl cyanide with 3.7g of ethyl acetate and add it to the reaction bottle, keep the temperature at the reflux temperature for 1h. Add the second initiator, dissolve 0.25g of azobisisopentyl cyanide with 6.5g of ethyl acetate and add it to the reaction bottle, keep the temperature at the reflux temperature for 2h. Add the third initiator, dissolve 0.18g of azobisisopentyl cyanide with 3.2g of ethyl acetate and add it to the reaction bottle, keep the temperature at the reflux temperature for 3h.

[0035] S4. After the reaction is completed, the temperature is lowered to below 50°C, and 56.4 g of methanol, 45.1 g of toluene, 0.47 g of aluminum acetylacetonate, and 1.5 g of acetylacetone are added and stirred evenly. Example 3

[0036] S1, put 42.6 g of isooctyl acrylate, 68.8 g of lauryl methacrylate, 34.2 g of methyl acrylate, 16.8 g of vinyl acetate, 9.97 g of methacrylic acid, 0.28 g of hydroxypropyl acrylate, 3.8 g of acrylonitrile, 6.5 g of FA2D, and 0.19 g of azobisisoheptyl cyanide into a 250 mL beaker, stir and mix well to obtain a mixed monomer;

[0037] S2. Add 216.8 g of ethyl acetate into a 1L four-necked flask equipped with a stirring paddle, a thermometer, and a reflux condenser, and heat it in a constant temperature water bath until the solvent refluxes stably (temperature 78°C). Add the mixed monomers evenly to the reaction bottle using a constant pressure dropping funnel at the solvent reflux temperature. The addition takes 2 hours. After the addition is completed, keep the reaction at the solvent reflux temperature for 2 hours.

[0038] S3, add the first initiator, dissolve 0.19g of azobisisoheptanone cyanide with 6.7g of ethyl acetate and add it to the reaction bottle, keep the temperature at the reflux temperature for 1h, add the second initiator, dissolve 0.27g of azobisisoheptanone cyanide with 7.8g of ethyl acetate and add it to the reaction bottle, keep the temperature at the reflux temperature for 1h. Add the third initiator, dissolve 0.19g of azobisisoheptanone cyanide with 4.2g of ethyl acetate and add it to the reaction bottle, keep the temperature at the reflux temperature for 2h.

[0039] S4. After the reaction is completed, the temperature is lowered to below 50°C, and 64.3 g of isopropanol, 32.1 g of acetone, 0.35 g of aluminum acetylacetonate, and 1.8 g of acetylacetone are added and stirred evenly. Example 4

[0040] S1. Add 82.6 g of isooctyl acrylate, 28.8 g of ethyl acrylate, 40.2 g of isobornyl acrylate, 22.8 g of butyl methacrylate, 12.9 g of acrylic acid, 0.47 g of glycidyl methacrylate, 4.8 g of acrylamide, 6.5 g of FA2D, and 0.14 g of dibenzoyl peroxide into a 250 mL beaker and stir to mix uniformly to obtain a mixed monomer;

[0041] S2. In a 1L four-necked flask equipped with a stirring paddle, a thermometer, and a reflux condenser, 180.9g of ethyl acetate and 35.8g of toluene were added, and heated in a constant temperature water bath until the solvent was stably refluxed (temperature 82°C). The mixed monomers were evenly added dropwise to the reaction bottle using a constant pressure dropping funnel at the solvent reflux temperature. The addition took 2h. After the addition was completed, the mixture was kept at the solvent reflux temperature for 2h.

[0042] S3, add the first initiator, dissolve 0.17g of dibenzoyl peroxide in 6.7g of ethyl acetate and add it to the reaction bottle, keep the temperature at the reflux temperature for 1h. Add the second initiator, dissolve 0.27g of dibenzoyl peroxide in 7.8g of ethyl acetate and add it to the reaction bottle, keep the temperature at the reflux temperature for 2h. Add the third initiator, dissolve 0.23g of dibenzoyl peroxide in 5.2g of ethyl acetate and add it to the reaction bottle, keep the temperature at the reflux temperature for 3h.

[0043] S4. After the reaction is completed, the temperature is lowered to below 50°C, and 24.7 g of ethanol, 71.1 g of acetone, 0.84 g of aluminum acetylacetonate, and 1.3 g of acetylacetone are added and stirred evenly.

[0044] The TPU car cover film acrylate pressure-sensitive adhesive prepared in Example 1-4 was evenly coated on a 25 μm PET release film using a doctor blade, baked at 120° C. for 2 min, and then transferred to a 150 μm TPU substrate to obtain a TPU tape sample. Finally, the sample was aged at 40° C. for 3 days before performance testing. Figure 2 These are the performance parameters of the acrylic pressure-sensitive adhesive for TPU car cover film prepared in Examples 1-4.

[0045] from Figure 2 It can be seen from the test results that the acrylic pressure-sensitive adhesive for TPU car cover film prepared by the present invention has a high peeling force, which can meet the construction requirements of quick pasting, and at the same time has good adhesion and excellent removability.

[0046] Although the present invention has been described above with reference to the embodiments, various modifications may be made thereto and parts thereof may be replaced by equivalents without departing from the scope of the present invention. In particular, as long as there is no structural conflict, the various features in the embodiments disclosed in the present invention may be used in combination with each other in any manner, and the fact that these combinations are not exhaustively described in this specification is only for the sake of omitting space and saving resources. Therefore, the present invention is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

Claims

1. An acrylic pressure-sensitive adhesive for TPU car cover film, characterized in that: The raw materials include the following weight percentages: soft monomer: 20-25%, hard monomer: 8-12%, functional monomer: 2-4%, adhesion promoting monomer: 0.2-1%, reactive polycaprolactone: 0.5-2%, initiator: 0.05-0.2%, solvent: 55-68%, curing agent: 0.15-0.5%; The adhesion promoting monomer is one or more of β-acryloxypropionic acid, acrylonitrile, and acrylamide; The specific structural formula of the reactive polycaprolactone is as follows: 。 2. The acrylic pressure-sensitive adhesive for TPU car cover film according to claim 1, characterized in that: The soft monomer is one or more of isooctyl acrylate, butyl acrylate, ethyl acrylate and lauryl methacrylate.

3. The acrylic pressure-sensitive adhesive for TPU car cover film according to claim 1, characterized in that: The hard monomer is one or more of methyl acrylate, methyl methacrylate, butyl methacrylate, isobornyl acrylate and vinyl acetate.

4. The acrylic pressure-sensitive adhesive for TPU car cover film according to claim 1, characterized in that: The functional monomer is one or more of acrylic acid, methacrylic acid, hydroxyethyl acrylate, hydroxypropyl acrylate, and glycidyl methacrylate.

5. A method for preparing an acrylic pressure-sensitive adhesive for TPU car cover film as claimed in claim 1, characterized in that: The specific steps are as follows: S1, mixing all soft monomers, hard monomers, functional monomers, adhesion promoting monomers, reactive polycaprolactone, and a portion of initiators to obtain a mixed monomer; S2, adding a portion of the solvent into the reaction vessel, heating to a temperature of 75-85°C, allowing the solvent to reflux stably, and then dripping the mixed monomer into the reaction vessel at the solvent reflux temperature for 2-4 hours. After the dripping of the mixed monomer is completed, the reaction is kept at the solvent reflux temperature for 2-4 hours; S3, adding the remaining initiator into the reaction vessel three times after dissolving it with a portion of the solvent, and keeping the reaction at the reflux temperature of the solvent for 1-3 hours after each addition; S4. After the reaction is completed, the temperature is lowered to below 50° C., and the remaining solvent and curing agent are added and stirred evenly to obtain the acrylic pressure-sensitive adhesive for TPU car cover film.

6. The method for preparing an acrylic pressure-sensitive adhesive for TPU car cover film according to claim 5, characterized in that: The amount of the initiator used in step S1 accounts for 15-25% of the total amount of the initiator.

7. The method for preparing an acrylic pressure-sensitive adhesive for TPU car cover film according to claim 5, characterized in that: The proportion of the amount of solvent used in step S2 to the total amount of solvent is 60-75%.

8. The method for preparing an acrylic pressure-sensitive adhesive for TPU car cover film according to claim 5, characterized in that: In step S3, the mass ratio of the solvent for dissolving the initiator to the initiator is 1:0.02-0.06.

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