Preparation method and application of liquid acrylic hot melt adhesive with high drawing force

Abstract

The invention discloses a preparation method and application of a high-drawing-force liquid acrylic hot melt adhesive, and relates to the technical field of high polymer materials. Raw materials comprise 38 to 40 parts of 2-ethylhexyl acrylate, 20 to 25 parts of n-butyl acrylate, 30 to 35 parts of methyl methacrylate, 5 to 8 parts of acrylic acid and 0.4 part of a free radical initiator azodiisobutyronitrile, and 120 parts of an ethyl acetate solvent is additionally weighed for dilution. The liquid acrylic hot melt adhesive has the advantages of favorable flowability, favorable self-stability, convenience in use, high cohesiveness, favorable curing effect and resistance to 85 DEG C / 85% humidity, and obviously enhances the drawing force of the acrylic hot melt adhesive.

Description

Technical Field

[0001] The invention relates to the technical field of polymer materials, and in particular to a preparation method and application of a high-pull-out-force liquid acrylic hot-melt adhesive. Background Art

[0002] The existing hot melt adhesive market is dominated by solid hot melt adhesives, which are mostly solid at room temperature and need to be heated and melted into liquid to flow before they can be used. Within a certain temperature range, the physical state changes with temperature, which has certain limitations. There are still some technical drawbacks in application, such as poor anti-aging and weather resistance. When taping capacitors in the tape field, residual adhesive is likely to appear on the metal pins of the capacitors. The tape cannot withstand 85℃ / 85% humidity for 500 hours, and the taped capacitors are prone to warping and separation. These problems affect the application quality and use of hot melt adhesives.

[0003] In order to meet the higher requirements for hot melt adhesive performance in the high-end manufacturing field, the inventors have developed a high-pull-out force liquid acrylic hot melt adhesive that can withstand 85°C / 85% humidity for 500 hours, has excellent high pull-out force performance and anti-aging performance, is environmentally friendly, odorless, and low-cost, and can pass the ROHS environmental test, effectively solving the shortcomings of existing traditional solid hot melt adhesives. Summary of the invention

[0004] In order to solve the shortcomings of the current solid hot melt adhesive, the present invention provides a preparation method and application of a high pull-out force liquid acrylic hot melt adhesive. The liquid acrylic hot melt adhesive has good fluidity and good self-stability, and is easy to use. It significantly improves the pull-out force of the acrylic hot melt adhesive, has strong adhesion, good curing effect, and is resistant to 85°C / 85% humidity.

[0005] To achieve the above object, the present invention adopts the following technical solutions:

[0006] A method for preparing a high-pull-out force liquid acrylic hot melt adhesive, wherein the raw materials include 38-40 parts of 2-ethylhexyl acrylate, 20-25 parts of n-butyl acrylate, 30-35 parts of methyl methacrylate, 5-8 parts of acrylic acid and 0.4 parts of azobisisobutyronitrile as a free radical initiator, in parts by weight. The preparation method comprises the following steps:

[0007] Step 1: Weigh 2-ethylhexyl acrylate, n-butyl acrylate, methyl methacrylate, acrylic acid and azobisisobutyronitrile as a free radical initiator respectively according to the above weight parts, and additionally weigh 120 parts of ethyl acetate solvent for subsequent dilution;

[0008] Step 2: Mix 2-ethylhexyl acrylate, n-butyl acrylate, methyl methacrylate and acrylic acid, and stir evenly to obtain a mixed monomer;

[0009] Step 3: Take 20 parts of mixed monomers, 0.05 parts of azobisisobutyronitrile as a free radical initiator and 60 parts of ethyl acetate solvent, mix and stir evenly, heat to 71-72°C and react for 100-120 minutes;

[0010] Step 4: maintaining the reaction temperature at 71-72°C, taking the remaining mixed monomers, 0.3 parts of azobisisobutyronitrile as a free radical initiator and 40 parts of ethyl acetate solvent, stirring and mixing them evenly, placing them into a separating funnel and dropping them for 180-240 minutes for polymerization reaction;

[0011] Step 5: Dilute and dissolve 0.05 parts of azobisisobutyronitrile, a free radical initiator, in 5 parts of ethyl acetate solvent, and place in a separatory funnel and drip for 30 minutes;

[0012] Step 6: Keep the temperature at 71-72°C for 180 minutes, then add the remaining 15 parts of ethyl acetate solvent into a separatory funnel and dropwise add to cool the mixture to obtain a high pull-out force liquid acrylic hot melt adhesive.

[0013] Furthermore, in step 3, the stirring is carried out in a four-necked beaker, and the rotation speed of the stirring component is between 200 and 600 R / min.

[0014] Furthermore, N2 protection is used during the reaction process from step 3 to step 6 to isolate the air and avoid oxidation.

[0015] Furthermore, the temperature control during step 3 to step 6 is protected by a cooling circulation device.

[0016] The invention also discloses the application of the preparation method of the high-pull-out force liquid acrylic hot-melt adhesive, which is applied to the bonding material of braided capacitors.

[0017] Compared with the prior art, the beneficial effects of the present invention are as follows: the liquid acrylic hot melt adhesive of the present invention is a hot melt acrylic adhesive prepared by a special synthesis process mainly based on the polymerization of acrylic acid monomers, adding an initiator for free radical polymerization, and introducing active groups into the main chain of its copolymer molecule to significantly improve the pull-out force of the acrylic hot melt adhesive, with strong adhesion, good curing effect, and resistance to 85°C / 85% humidity. The liquid acrylic hot melt adhesive has good fluidity and good self-stability, is easy to use, and can be widely used in the heat sealing and bonding scenarios of braiding tapes in the production process of parts such as capacitors and resistors. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 is a flow chart of the preparation method of the present invention;

[0019] Figure 2 It is the viscosity value test data of the hot melt adhesive prepared by the three experimental groups in the embodiment;

[0020] Figure 3 It is the pull-out force test data of the hot melt adhesive prepared in Experimental Group 1 in the embodiment;

[0021] Figure 4 It is the pull-out force test data of the hot melt adhesive prepared in Experimental Group 2 in the embodiment;

[0022] Figure 5 It is the pull-out force test data of the hot melt adhesive prepared in Experimental Group 3 in the embodiment;

[0023] Figure 6 This is a diagram showing the use of the liquid acrylic hot melt adhesive prepared by the present invention for braided capacitors;

[0024] Figure 7 This is the ROHS test report of the liquid acrylic hot melt adhesive prepared by the present invention. DETAILED DESCRIPTION

[0025] The technical solution of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the invention, rather than 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] like Figure 1 As shown, a method for preparing a high pull-out force liquid acrylic hot melt adhesive, in parts by weight, the raw materials include 38-40 parts of 2-ethylhexyl acrylate, 20-25 parts of n-butyl acrylate, 30-35 parts of methyl methacrylate, 5-8 parts of acrylic acid and 0.4 parts of azobisisobutyronitrile as a free radical initiator, and the preparation method includes the following steps:

[0027] Step 1: Weigh 2-ethylhexyl acrylate, n-butyl acrylate, methyl methacrylate, acrylic acid and azobisisobutyronitrile as a free radical initiator respectively according to the above weight parts, and additionally weigh 120 parts of ethyl acetate solvent for subsequent dilution;

[0028] Step 2: Mix 2-ethylhexyl acrylate, n-butyl acrylate, methyl methacrylate and acrylic acid, and stir evenly using a magnetic stirrer to obtain a mixed monomer;

[0029] Step 3: Take 20 parts of the mixed monomer, 0.05 parts of azobisisobutyronitrile as a free radical initiator and 60 parts of ethyl acetate solvent and mix them in a beaker, stir them evenly with a magnetic stirrer, place them in a four-necked beaker and stir (the stirring component speed is 200-600R / min), and heat them to 71-72°C for reaction for 100-120min;

[0030] Step 4: maintaining the reaction temperature at 71-72° C., taking the remaining mixed monomers, 0.3 parts of azobisisobutyronitrile as a free radical initiator and 40 parts of ethyl acetate solvent, stirring and mixing them evenly, placing them into a separating funnel and dropping them for 180-240 minutes for polymerization reaction, and using N2 protection in the entire polymerization reaction process (steps 3 to 6) to effectively isolate the product from contact with air, avoid oxidation, and improve the quality purity and stability of the product. In addition, the entire polymerization reaction process (steps 3 to 6) is preferably protected by a cooling circulation device, which is also helpful for subsequent effective cooling;

[0031] Step 5: Dilute and dissolve 0.05 parts of azobisisobutyronitrile, a free radical initiator, in 5 parts of ethyl acetate solvent, and place in a separatory funnel and drip for 30 minutes;

[0032] Step 6: Keep the temperature at 71-72°C for 180 minutes, then add the remaining 15 parts of ethyl acetate solvent into a separatory funnel and dropwise add to cool the mixture to obtain a high pull-out force liquid acrylic hot melt adhesive.

[0033] Example:

[0034] Experimental Group 1

[0035] A1: Weigh 38 parts of 2-ethylhexyl acrylate, 20 parts of n-butyl acrylate, 30 parts of methyl methacrylate, 5 parts of acrylic acid and 0.4 parts of azobisisobutyronitrile as a free radical initiator respectively by weight, and additionally weigh 120 parts of ethyl acetate solvent;

[0036] A2: Mix 2-ethylhexyl acrylate, n-butyl acrylate, methyl methacrylate and acrylic acid, and stir them evenly using a magnetic stirrer to obtain a mixed monomer;

[0037] A3: Take 20 parts of mixed monomers, 0.05 parts of azobisisobutyronitrile as a free radical initiator and 60 parts of ethyl acetate solvent and mix them in a beaker, stir them evenly with a magnetic stirrer, place them in a four-necked beaker, stir, and heat to 71-72°C for reaction for 100-120 minutes;

[0038] A4: Maintaining the reaction temperature at 71-72°C, take the remaining mixed monomers, 0.3 parts of azobisisobutyronitrile as a free radical initiator and 40 parts of ethyl acetate solvent, stir and mix them evenly, then place them into a separating funnel and drip them for 180-240 minutes for polymerization reaction;

[0039] A5: Dilute and dissolve 0.05 parts of azobisisobutyronitrile, a free radical initiator, in 5 parts of ethyl acetate solvent, and place in a separatory funnel and drip for 30 minutes;

[0040] A6: Keep the temperature at 71-72°C for 180 minutes, then add the remaining 15 parts of ethyl acetate solvent into a separatory funnel and dropwise cool it to obtain a high pull-out force liquid acrylic hot melt adhesive.

[0041] Experimental Group 2

[0042] A1: Weigh 39 parts of 2-ethylhexyl acrylate, 23 parts of n-butyl acrylate, 32.5 parts of methyl methacrylate, 6 parts of acrylic acid and 0.4 parts of azobisisobutyronitrile as a free radical initiator respectively by weight, and additionally weigh 120 parts of ethyl acetate solvent;

[0043] A2: Mix 2-ethylhexyl acrylate, n-butyl acrylate, methyl methacrylate and acrylic acid, and stir them evenly using a magnetic stirrer to obtain a mixed monomer;

[0044] A3: Take 20 parts of mixed monomers, 0.05 parts of azobisisobutyronitrile as a free radical initiator and 60 parts of ethyl acetate solvent and mix them in a beaker, stir them evenly with a magnetic stirrer, place them in a four-necked beaker, stir, and heat to 71-72°C for reaction for 100-120 minutes;

[0045] A4: Maintaining the reaction temperature at 71-72°C, take the remaining mixed monomers, 0.3 parts of azobisisobutyronitrile as a free radical initiator and 40 parts of ethyl acetate solvent, stir and mix them evenly, then place them into a separating funnel and drip them for 180-240 minutes for polymerization reaction;

[0046] A5: Dilute and dissolve 0.05 parts of azobisisobutyronitrile, a free radical initiator, in 5 parts of ethyl acetate solvent, and place in a separatory funnel and drip for 30 minutes;

[0047] A6: Keep the temperature at 71-72°C for 180 minutes, then add the remaining 15 parts of ethyl acetate solvent into a separatory funnel and dropwise cool it to obtain a high pull-out force liquid acrylic hot melt adhesive.

[0048] Experimental Group 3

[0049] A1: Weigh 40 parts of 2-ethylhexyl acrylate, 25 parts of n-butyl acrylate, 35 parts of methyl methacrylate, 8 parts of acrylic acid and 0.4 parts of azobisisobutyronitrile as a free radical initiator respectively by weight, and additionally weigh 120 parts of ethyl acetate solvent;

[0050] A2: Mix 2-ethylhexyl acrylate, n-butyl acrylate, methyl methacrylate and acrylic acid, and stir them evenly using a magnetic stirrer to obtain a mixed monomer;

[0051] A3: Take 20 parts of mixed monomers, 0.05 parts of azobisisobutyronitrile as a free radical initiator and 60 parts of ethyl acetate solvent and mix them in a beaker, stir them evenly with a magnetic stirrer, place them in a four-necked beaker, stir, and heat to 71-72°C for reaction for 100-120 minutes;

[0052] A4: Maintaining the reaction temperature at 71-72°C, take the remaining mixed monomers, 0.3 parts of azobisisobutyronitrile as a free radical initiator and 40 parts of ethyl acetate solvent, stir and mix them evenly, then place them into a separating funnel and drip them for 180-240 minutes for polymerization reaction;

[0053] A5: Dilute and dissolve 0.05 parts of azobisisobutyronitrile, a free radical initiator, in 5 parts of ethyl acetate solvent, and place in a separatory funnel and drip for 30 minutes;

[0054] A6: Keep the temperature at 71-72°C for 180 minutes, then add the remaining 15 parts of ethyl acetate solvent into a separatory funnel and dropwise cool it to obtain a high pull-out force liquid acrylic hot melt adhesive.

[0055] The hot melt adhesives prepared in the above three experimental groups were tested for viscosity using a NDJ-5S rotary digital viscometer. Figure 2 As shown, it can be seen that the viscosity values ​​of the three experimental groups are gradually increasing. Then, the pull-out force test is carried out by the pointer-type NK-300N push-pull force gauge tester. The pull-out force test results of the hot melt adhesive prepared in experimental groups 1, 2, and 3 are combined with Figure 3 , Figure 4 , Figure 5 As shown, it can be seen that when the viscosity value increases significantly, the pull-out force of the liquid acrylic hot melt adhesive also increases.

[0056] In order to verify the superiority of the liquid acrylic hot melt adhesive prepared by the method of the present invention, it was made into a masking tape, and then the capacitor was taped and laminated with kraft paper. After being tested in a constant temperature and humidity chamber, it was found to be able to withstand 85°C / 85% humidity for 500 hours. The results are shown in Table 1. Figure 6 As shown in the figure, it can be seen that the liquid acrylic hot melt adhesive prepared by the method of the present invention has good adhesion, and the braided capacitor does not have the phenomenon of warping, separation or falling off.

[0057] In addition, the liquid acrylic hot melt adhesive prepared by the method of the present invention can pass the ROHS environmental protection test, and the test results are combined with Figure 7 As shown, it can also be seen from the figure that the liquid acrylic hot melt adhesive prepared by the method of the present invention has excellent environmental protection characteristics.

[0058] It will be apparent to those skilled in the art that the invention is not limited to the details of the exemplary embodiments described above and that the invention can be implemented in other forms of assembly without departing from the spirit or essential features of the invention. Therefore, the embodiments should be considered in all respects as exemplary and non-restrictive, and the scope of the invention is defined by the appended claims rather than the foregoing description, and it is intended that all variations within the meaning and range of equivalents of the claims be included in the invention. Any reference numeral in a claim should not be considered as limiting the claim to which it relates.

[0059] In addition, it should be understood that although the present specification is described according to implementation modes, not every implementation mode contains only one independent technical solution. This description of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment may also be appropriately combined to form other implementation modes that can be understood by those skilled in the art.

Claims

1. A method for preparing a high pull-out force liquid acrylic hot melt adhesive, characterized in that: In parts by weight, the raw materials include 38-40 parts of 2-ethylhexyl acrylate, 20-25 parts of n-butyl acrylate, 30-35 parts of methyl methacrylate, 5-8 parts of acrylic acid and 0.4 parts of azobisisobutyronitrile as a free radical initiator. The preparation method includes the following steps: Step 1: Weigh 2-ethylhexyl acrylate, n-butyl acrylate, methyl methacrylate, acrylic acid and azobisisobutyronitrile as a free radical initiator respectively according to the above weight parts, and additionally weigh 120 parts of ethyl acetate solvent for subsequent dilution; Step 2: Mix 2-ethylhexyl acrylate, n-butyl acrylate, methyl methacrylate and acrylic acid, and stir evenly to obtain a mixed monomer; Step 3: Take 20 parts of mixed monomers, 0.05 parts of azobisisobutyronitrile as a free radical initiator and 60 parts of ethyl acetate solvent, mix and stir evenly, heat to 71-72°C and react for 100-120 minutes; Step 4: maintaining the reaction temperature at 71-72°C, taking the remaining mixed monomers, 0.3 parts of azobisisobutyronitrile as a free radical initiator and 40 parts of ethyl acetate solvent, stirring and mixing them evenly, placing them into a separating funnel and dropping them for 180-240 minutes for polymerization reaction; Step 5: Dilute and dissolve 0.05 parts of azobisisobutyronitrile, a free radical initiator, in 5 parts of ethyl acetate solvent, and place in a separatory funnel and drip for 30 minutes; Step 6: Keep the temperature at 71-72°C for 180 minutes, then add the remaining 15 parts of ethyl acetate solvent into a separatory funnel and dropwise add to cool the mixture to obtain a high pull-out force liquid acrylic hot melt adhesive.

2. The method for preparing a high pull-out force liquid acrylic hot melt adhesive according to claim 1, characterized in that: In step 3, the stirring is carried out in a four-necked beaker, and the rotation speed of the stirring component is between 200 and 600 R / min.

3. The method for preparing a high pull-out force liquid acrylic hot melt adhesive according to claim 1, characterized in that: During the reaction process from step 3 to step 6, N2 protection is used to isolate the air and avoid oxidation.

4. The method for preparing a high pull-out force liquid acrylic hot melt adhesive according to claim 1, characterized in that: The temperature control during step 3 to step 6 is protected by a cooling circulation device.

5. Application of the method for preparing a high pull-out force liquid acrylic hot melt adhesive according to any one of claims 1 to 4, characterized in that: Adhesive material for tape capacitors.

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