Single-component primer for thermally activated polyurethane adhesive film and preparation method of single-component primer

Abstract

The invention relates to the technical field of pressure-sensitive adhesives, in particular to a single-component primer for a thermally activated polyurethane adhesive film and a preparation method of the single-component primer. The glue synthesized by using the method belongs to an acrylate prepolymer, the acrylate prepolymer is specially designed according to a product formula for improving the bonding strength of a thermally activated polyurethane adhesive film to a substrate of an electronic consumer product, the formula design is simple, the synthesis process is simple and convenient, and a specific coupling agent and a solvent are matched, so that the adhesive strength is greatly improved. The single-component primer for the thermally activated polyurethane adhesive film is prepared. The single-component primer is used in cooperation with a thermal activation polyurethane adhesive film, the adhesive applying process is simple, convenient and rapid, and the bonding strength of the thermal activation polyurethane adhesive film to SUS, 5-series aluminum, anode aluminum, nickel-plated aluminum and other base materials can be improved. The single-component primer has the advantages of good stability, volatile solvent, quick drying at normal temperature within 5-10 minutes, no benzene toxic solvent, low and adjustable solid content, and obvious effect of improving the bonding strength when being used as a special primer adhesion promoter for a thermal activation polyurethane adhesive film.

Description

Technical Field

[0001] The invention relates to the technical field of pressure-sensitive adhesives, in particular to a single-component primer for a heat-activated polyurethane adhesive film and a preparation method thereof. Background Art

[0002] In the process of assembling electronic consumer products, adhesives are needed to bond the electronic module units to the substrate of the electronic product motherboard. After the traditional polyurethane adhesive is applied, it takes a long time to cure to achieve the ideal bonding strength, which affects the production and assembly efficiency of electronic products. Heat-activated polyurethane film is more and more widely used in consumer electronic products because of its convenience in use, the ability to achieve the required bonding strength in a very short time, good shock and drop resistance, and chemical corrosion resistance. As electronic consumer products become lighter, thinner and smaller, the bonding area of ​​electronic adhesives is reduced, but the requirements for the bonding strength of electronic adhesives remain the same.

[0003] In order to meet the higher bonding strength requirements for electronic product assembly, it is necessary to develop a one-component primer to reinforce the heat-activated polyurethane film used for bonding electronic consumer products. The reinforced film has a higher bonding strength, which can effectively prevent the back panel substrate of electronic consumer products from debonding with the mainboard substrate, thereby improving the yield rate of electronic consumer products.

[0004] In order to solve the above problems, the present invention provides a one-component primer for a heat-activated polyurethane adhesive film and a preparation method thereof. Summary of the invention

[0005] The object of the present invention is to provide a one-component primer for heat-activated polyurethane adhesive film and a preparation method thereof, so as to solve the problems raised in the above-mentioned background technology.

[0006] In order to solve the above technical problems, the present invention provides the following technical solutions:

[0007] A one-component primer for a heat-activated polyurethane film comprises the following components by weight:

[0008]

[0009] The synthetic glue is an acrylate prepolymer.

[0010] More optimally, the first solvent is anhydrous ethanol and the second solvent is isopropyl acetate.

[0011] More optimally, acrylic monomers one to four are various combinations of methyl methacrylate, methyl acrylate, ethyl acrylate, ethyl methacrylate, butyl acrylate, butyl methacrylate, isooctyl acrylate, N-vinyl pyrrolidone, and 2-hydroxyethyl methacrylate.

[0012] More preferably, the initiator is an azo initiator or a peroxide initiator.

[0013] The present invention also provides a method for preparing a one-component primer for a heat-activated polyurethane film, which is used to prepare any one of the above-mentioned acrylate prepolymers, comprising the following steps:

[0014] S1, add 5 parts of acrylic acid monomer 1, 40 parts of acrylic acid monomer 2, 55 parts of acrylic acid monomer 3, 2 parts of acrylic acid monomer 4, 45 parts of solvent anhydrous ethanol, and 45 parts of isopropyl acetate into a dry four-necked reaction flask equipped with a serpentine condenser and a separatory funnel, and stir and heat to 65°C at a speed of 200r / min.

[0015] S2, dissolving 0.1 parts of azobisisobutyronitrile in 10 parts of isopropyl acetate and 10 parts of anhydrous ethanol and adding the mixture into a separatory funnel, adding the first batch of initiator dropwise within 30 minutes, and then keeping the mixture at 65°C for 30 minutes.

[0016] S3, dissolving 0.1 parts of azobisisobutyronitrile in 10 parts of isopropyl acetate and 10 parts of anhydrous ethanol and adding the mixture into a separatory funnel, then heating to 75°C, adding the second batch of initiator dropwise within 30 minutes, and reacting at 75°C for 4.5 hours.

[0017] S4, dissolving 0.3 parts of azobisisobutyronitrile in 10 parts of isopropyl acetate and adding the mixture into a separatory funnel, heating the mixture to 80° C., and then rapidly dropping the third batch of initiator.

[0018] S5, after reacting for 1 hour, 20 parts of isopropyl acetate were added and stirred for 20 minutes, and then the temperature was lowered and the material was discharged to prepare the acrylate prepolymer. Nitrogen was required to be passed for protection during the entire reaction process.

[0019] More optimally, the stirring rates in steps S1-S5 are all 200 r / min.

[0020] More optimally, in steps S1-S5, the initiator accounts for 1-3‰ of the amount of acrylic prepolymer.

[0021] Compared with the prior art, the beneficial effects achieved by the present invention are:

[0022] (1) The present invention aims to provide a preparation method of a one-component primer for a heat-activated polyurethane adhesive film, wherein the synthesized adhesive is an acrylate prepolymer.

[0023] (2) In the present invention, the prepared acrylate prepolymer is a product formula designed specifically for improving the bonding strength of the heat-activated polyurethane film to the substrate of electronic consumer products. The formula design is not complicated and the synthesis process is simple. This acrylate prepolymer is combined with a specific coupling agent and solvent to prepare a one-component primer for the heat-activated polyurethane film.

[0024] (3) In the present invention, the prepared one-component primer is used in combination with the heat-activated polyurethane film, and the gluing process is simple and quick, which can improve the bonding strength of the heat-activated polyurethane film to substrates such as SUS, ink glass, PC, and nickel-plated aluminum. The one-component primer has good stability, the solvent is easily volatile and dries quickly at room temperature within 5-10 minutes, does not contain benzene-based toxic solvents, has a low and adjustable solid content, and is used as a special primer adhesion promoter for the heat-activated polyurethane film, and has a significant effect of improving the bonding strength. DETAILED DESCRIPTION

[0025] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only 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 making creative work are within the scope of protection of the present invention.

[0026] The invention provides a method for preparing a single-component primer for a heat-activated polyurethane adhesive film, and provides several embodiments to detect the dynamic shear performance of the finished product before and after the substrate is coated.

[0027] The present invention first synthesizes an acrylate prepolymer, and then dissolves the synthesized acrylate prepolymer in a solvent containing a coupling agent in a certain proportion to obtain a single-component primer for a heat-activated polyurethane film. The specific method and formula for synthesizing the acrylate prepolymer in each embodiment are as follows.

[0028] Example 1

[0029] 5 parts of ethyl acrylate, 40 parts of butyl methacrylate, 50 parts of N-vinyl pyrrolidone, 3 parts of 2-hydroxyethyl methacrylate, 45 parts of anhydrous ethanol as solvent, and 45 parts of isopropyl acetate were added to a dry four-necked reaction flask equipped with a serpentine condenser and a separatory funnel, and heated to 65°C with stirring at a speed of 200 r / min. 0.1 parts of azobisisobutyronitrile were dissolved in 10 parts of isopropyl acetate and 10 parts of anhydrous ethanol and added to the separatory funnel. The first batch of initiators was added dropwise within 30 minutes, and then kept at 65°C for 30 minutes.

[0030] 0.1 parts of azobisisobutyronitrile were dissolved in 10 parts of isopropyl acetate and 10 parts of anhydrous ethanol and added to a separatory funnel, then heated to 75°C, the second batch of initiators were added dropwise within 30 minutes, and reacted at 75°C for 4.5 hours, 0.3 parts of azobisisobutyronitrile were dissolved in 10 parts of isopropyl acetate and added to a separatory funnel, heated to 80°C, the third batch of initiators were quickly added dropwise, and then reacted for 1 hour, 20 parts of isopropyl acetate were added, stirred for 20 minutes, cooled and discharged to prepare the acrylate prepolymer. Nitrogen was passed through the entire reaction process for protection.

[0031] Example 2

[0032] 5 parts of 2-ethylhexyl acrylate, 50 parts of butyl methacrylate, 55 parts of N-vinyl pyrrolidone, 2 parts of 2-hydroxyethyl methacrylate, 45 parts of anhydrous ethanol as solvent, and 45 parts of isopropyl acetate were added to a dry four-necked reaction flask equipped with a serpentine condenser and a separatory funnel, and heated to 65°C with stirring at a speed of 200 r / min. 0.1 parts of azobisisobutyronitrile were dissolved in 10 parts of isopropyl acetate and 10 parts of anhydrous ethanol and added to the separatory funnel. The first batch of initiators was added dropwise within 30 minutes, and then kept at 65°C for 30 minutes.

[0033] 0.1 parts of azobisisobutyronitrile were dissolved in 10 parts of isopropyl acetate and 10 parts of anhydrous ethanol and added to a separatory funnel, then heated to 75°C, the second batch of initiators were added dropwise within 30 minutes, and reacted at 75°C for 4.5 hours, 0.3 parts of azobisisobutyronitrile were dissolved in 10 parts of isopropyl acetate and added to a separatory funnel, heated to 80°C, the third batch of initiators were quickly added dropwise, and then reacted for 1 hour, 20 parts of isopropyl acetate were added, stirred for 20 minutes, cooled and discharged to prepare the acrylate prepolymer. Nitrogen was passed through the entire reaction process for protection.

[0034] Example 3

[0035] 40 parts of butyl acrylate, 55 parts of N-vinyl pyrrolidone, 2 parts of 2-hydroxyethyl methacrylate, 45 parts of solvent anhydrous ethanol, and 45 parts of isopropyl acetate were added to a dry four-necked reaction flask equipped with a serpentine condenser and a separatory funnel, and heated to 65°C with stirring at a speed of 200 r / min. 0.1 parts of azobisisobutyronitrile were dissolved in 10 parts of isopropyl acetate and 10 parts of anhydrous ethanol and added to the separatory funnel. The first batch of initiators was added dropwise within 30 minutes, and then kept at 65°C for 30 minutes.

[0036] 0.1 parts of azobisisobutyronitrile were dissolved in 10 parts of isopropyl acetate and 10 parts of anhydrous ethanol and added to a separatory funnel, then heated to 75°C, the second batch of initiators were added dropwise within 30 minutes, and reacted at 75°C for 4.5 hours, 0.3 parts of azobisisobutyronitrile were dissolved in 10 parts of isopropyl acetate and added to a separatory funnel, heated to 80°C, the third batch of initiators were quickly added dropwise, and then reacted for 1 hour, 20 parts of isopropyl acetate were added, stirred for 20 minutes, cooled and discharged to prepare the acrylate prepolymer. Nitrogen was passed through the entire reaction process for protection.

[0037] Example 4

[0038] 5 parts of methyl methacrylate, 40 parts of butyl acrylate, 55 parts of N-vinyl pyrrolidone, 2 parts of 2-hydroxyethyl methacrylate, 45 parts of anhydrous ethanol as solvent, and 45 parts of isopropyl acetate were added to a dry four-necked reaction flask equipped with a serpentine condenser and a separatory funnel, and heated to 65°C with stirring at a speed of 200 r / min. 0.1 parts of azobisisobutyronitrile were dissolved in 10 parts of isopropyl acetate and 10 parts of anhydrous ethanol and added to the separatory funnel. The first batch of initiators were added dropwise within 30 minutes, and then kept at 65°C for 30 minutes.

[0039] 0.1 parts of azobisisobutyronitrile were dissolved in 10 parts of isopropyl acetate and 10 parts of anhydrous ethanol and added to a separatory funnel, then heated to 75°C, the second batch of initiators were added dropwise within 30 minutes, and reacted at 75°C for 4.5 hours, 0.3 parts of azobisisobutyronitrile were dissolved in 10 parts of isopropyl acetate and added to a separatory funnel, heated to 80°C, the third batch of initiators were quickly added dropwise, and then reacted for 1 hour, 20 parts of isopropyl acetate were added, stirred for 20 minutes, cooled and discharged to prepare the acrylate prepolymer. Nitrogen was passed through the entire reaction process for protection.

[0040] Example 5

[0041] 5 parts of methyl methacrylate, 40 parts of butyl methacrylate, 55 parts of N-vinyl pyrrolidone, 2 parts of 2-hydroxyethyl methacrylate, 45 parts of solvent anhydrous ethanol, and 45 parts of isopropyl acetate were added to a dry four-necked reaction flask equipped with a serpentine condenser and a separatory funnel, and heated to 65°C with stirring at a speed of 200 r / min. 0.1 parts of azobisisobutyronitrile were dissolved in 10 parts of isopropyl acetate and 10 parts of anhydrous ethanol and added to the separatory funnel. The first batch of initiator was added dropwise within 30 minutes, and then kept at 65°C for 30 minutes;

[0042] 0.1 parts of azobisisobutyronitrile were dissolved in 10 parts of isopropyl acetate and 10 parts of anhydrous ethanol and added to a separatory funnel, then heated to 75°C, the second batch of initiators were added dropwise within 30 minutes, and reacted at 75°C for 4.5 hours, 0.3 parts of azobisisobutyronitrile were dissolved in 10 parts of isopropyl acetate and added to a separatory funnel, heated to 80°C, the third batch of initiators were quickly added dropwise, and then reacted for 1 hour, 20 parts of isopropyl acetate were added, stirred for 20 minutes, cooled and discharged to prepare the acrylate prepolymer. Nitrogen was passed through the entire reaction process for protection.

[0043] After the acrylate prepolymer is obtained, a one-component primer for heat-activated polyurethane film is prepared:

[0044] The acrylate prepolymers synthesized in Examples 1-5 were tested for their solid content and molecular weight.

[0045] The specific test method for solid content is to weigh W1 grams (about 1 gram) of acrylic prepolymer using an electronic balance with a precision of 1 part per ten thousand and place it in a W2 gram aluminum foil dish, bake it in an oven at 120°C for 2 hours, take out the aluminum foil dish with the prepolymer and weigh W3. Specific solid content = (W3-W2) / W1*100%.

[0046] The molecular weight of the acrylic acid prepolymer was tested by gel chromatography permeameter, with polystyrene as the standard sample and tetrahydrofuran as the mobile phase. The number average relative molecular weight of the synthesized acrylic acid prepolymers 1-5 was measured to be between 35000 and 45000.

[0047] The acrylate prepolymer synthesized in Examples 1-5 was dissolved in ethyl acetate or isopropanol solvent containing a coupling agent at a ratio of 4% to 8% by weight to prepare a single-component primer for a heat-activated polyurethane adhesive film.

[0048] After obtaining the finished product of the one-component primer for heat-activated polyurethane film, the shear strength test was performed on it. The specific method is as follows: the shear strength of the prepared sample is based on the test method for dynamic shear strength of adhesive tapes in GB / T33332-2016, and the dynamic shear strength test is performed using an Instron mechanical testing machine at 25±2°C and a speed of 10mm / min. The obtained performance test results are shown in Table 1.

[0049] Table 1 Dynamic shear strength performance of substrates treated with primers prepared in various embodiments (unit: MPa)

[0050]

[0051]

[0052] It can be concluded from the experimental results in Table 1 that after the substrate is treated with the one-component primer for polyurethane of the present invention, the dynamic shear bonding strength between the heat-activated polyurethane film and the stainless steel substrate, aluminum substrate, and nickel-plated aluminum substrate is increased by about 1.6 times, and the bonding performance is significantly improved. The bonding strength of the heat-activated polyurethane film to the metal substrate is significantly improved, which can greatly improve the yield of the film in the product application process.

[0053] The single-component primer for the heat-activated polyurethane adhesive film of the present invention has the advantages of simple preparation process, good storage stability of the components, simple sizing process, use of environmentally friendly solvents, and the like.

[0054] Table 2 Physical properties of one-component primer for heat-activated polyurethane film

[0055] Primer Type Example 1 Example 2 Example 3 Example 4 Example 5 Solid content (%) 6 6 6 6 6 Surface drying time (min) 5-10 5-10 5-10 5-10 5-10

[0056] From the data in Table 2, it can be concluded that the single-component primer for heat-activated polyurethane adhesive film prepared by the present invention has low solid content, is easy to dry on the surface, and can significantly reduce production costs. In addition, the primer can be applied by spraying or manual coating, and the sizing process is flexible and simple.

[0057] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device.

[0058] Finally, it should be noted that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art can still modify the technical solutions described in the aforementioned embodiments or replace some of the technical features therein by equivalents. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A one-component primer for a heat-activated polyurethane film, characterized in that: The composition includes the following components by weight: Acrylic acid monomer - 5-10 parts Acrylic acid monomer 2 30-50 parts Acrylic acid monomer 3 40-60 parts Acrylic acid monomer 1-5 parts Solvent 1 60-80 parts Solvent 2 80-100 parts Initiator 0.3-1 part; The synthetic glue is an acrylate prepolymer.

2. The one-component primer for heat-activated polyurethane film according to claim 1, characterized in that: The first solvent is anhydrous ethanol, and the second solvent is isopropyl acetate.

3. The one-component primer for heat-activated polyurethane film and the preparation method thereof according to claim 1, characterized in that: The acrylic monomers one to four are various combinations of methyl methacrylate, methyl acrylate, ethyl acrylate, ethyl methacrylate, butyl acrylate, butyl methacrylate, isooctyl acrylate, N-vinyl pyrrolidone, and 2-hydroxyethyl methacrylate.

4. The one-component primer for heat-activated polyurethane film according to claim 1, characterized in that: The initiator is an azo initiator and a peroxide initiator.

5. A method for preparing a one-component primer for a heat-activated polyurethane film, used for preparing any one of the acrylate prepolymers as claimed in claims 1 to 4, characterized in that: The steps include: S1, add 5 parts of acrylic acid monomer 1, 40 parts of acrylic acid monomer 2, 55 parts of acrylic acid monomer 3, 2 parts of acrylic acid monomer 4, 45 parts of solvent anhydrous ethanol, and 45 parts of isopropyl acetate into a dry four-necked reaction flask equipped with a serpentine condenser and a separatory funnel, and stir and heat to 65°C at a speed of 200r / min. S2, dissolving 0.1 parts of azobisisobutyronitrile in 10 parts of isopropyl acetate and 10 parts of anhydrous ethanol and adding the mixture into a separatory funnel, adding the first batch of initiator dropwise within 30 minutes, and then keeping the mixture at 65°C for 30 minutes. S3, dissolving 0.1 parts of azobisisobutyronitrile in 10 parts of isopropyl acetate and 10 parts of anhydrous ethanol and adding the mixture into a separatory funnel, then heating to 75°C, adding the second batch of initiator dropwise within 30 minutes, and reacting at 75°C for 4.5 hours. S4, dissolving 0.3 parts of azobisisobutyronitrile in 10 parts of isopropyl acetate and adding the mixture into a separatory funnel, heating the mixture to 80° C., and then rapidly dropping the third batch of initiator. S5, after reacting for 1 hour, 20 parts of isopropyl acetate were added and stirred for 20 minutes, and then the temperature was lowered and the material was discharged to prepare the acrylate prepolymer. Nitrogen was required to be passed for protection during the entire reaction process.

6. The method for preparing a one-component primer for a heat-activated polyurethane film according to claim 1, characterized in that: The stirring rates in steps S1-S5 are all 200 r / min.

7. The method for preparing a one-component primer for a heat-activated polyurethane film according to claim 1, characterized in that: In the steps S1-S5, the initiator accounts for 1-3‰ of the amount of acrylic acid prepolymer.

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