Adhesive for improving adhesion of non-woven cloth and epoxy primer and surface modification method

Abstract

The invention provides an adhesive for improving adhesion of a non-woven fabric and an epoxy primer and a surface modification method, and belongs to the technical field of high polymer materials, oligomer polyol, a hydrophilic chain extender and diisocyanate are subjected to a pre-reaction to prepare a prepolymer with a certain molecular weight, then the prepolymer is emulsified in water by a phase transfer method, and then chain extension is performed to prepare the non-woven fabric with the epoxy primer. The adhesive system simultaneously contains a polar functional group and a non-polar functional group; the non-polar non-woven cloth can be better combined with the polar epoxy primer, a surfactant is further added into the synthesized adhesive for modification, so that the adhesive can be better spread on the surface of the PE non-woven cloth, the adhesion between the non-woven cloth and the primer is improved, and by optimizing the operation process, the service life of the non-polar non-woven cloth is prolonged. And the efficient modification method which is more convenient, low in cost, capable of being industrially implemented and suitable for popularization and application is obtained.

Description

Technical Field

[0001] This invention belongs to the field of polymer materials technology, and in particular, it relates to an adhesive and surface modification method for improving the adhesion between nonwoven fabric and epoxy primer, which can effectively improve the adhesion effect between ultra-high molecular weight polyethylene fiber nonwoven fabric and epoxy primer. Background Technology

[0002] Ultra-high molecular weight polyethylene (UHMWPE) fiber is a man-made organic fiber that was successfully developed and prepared in the 1970s. It is the fourth high-performance fiber after carbon fiber, boron fiber and aramid fiber.

[0003] Because UHMWPE fiber is prepared through gel spinning-thermal stretching, its molecular chains are fully extended, with a crystallinity of over 85% and an orientation degree of nearly 100%, resulting in excellent mechanical properties. In addition, it combines low density, high strength, and high modulus, and its toughness is particularly outstanding. During plastic deformation, it absorbs 3 to 5 times more energy than polycarbonate, which is known for its impact resistance. Based on these superior properties, UHMWPE fiber composites are widely used in safety protection fields such as bulletproofing and explosion protection.

[0004] However, UHMWPE fiber (ultra-high molecular weight polyethylene fiber) is a non-polar material whose molecular chain consists only of methylene groups. Its surface energy is extremely low, making it difficult to form a good interfacial bond with the matrix material. This leads to interlaminar damage in UHMWPE fiber composites during use, and the fiber phase and matrix phase are prone to debonding and separation. Therefore, the poor surface adhesion of UHMWPE fiber limits its practical application in composite materials.

[0005] To overcome the above shortcomings, current methods involve modifying the surface of ultra-high molecular weight fibers to address the issue of poor adhesion. The main methods employed include:

[0006] Plasma modification, surface oxidation modification, corona discharge treatment, ultraviolet grafting modification, X-ray radiation grafting, and coating modification, etc.

[0007] Although the above modification methods can obtain UHMWPE fibers with enhanced surface adhesion, the post-processing is cumbersome, inefficient, and costly, which greatly limits its industrial application and cost control.

[0008] Therefore, it is necessary to study an efficient modification method that is stable on the fiber surface, easy to obtain, improves surface adhesion, and can be industrialized. Summary of the Invention

[0009] To address the aforementioned technical problems, this invention provides a surface modification method and adhesive for improving the adhesion between non-woven fabric and epoxy primer. By uniformly coating a layer of adhesive onto the surface of the non-woven fabric, the adhesive's molecular structure contains both polar and non-polar groups. The polar groups interact with the epoxy primer, while the non-polar groups are tightly bonded to the non-woven fabric, thereby achieving a strong bond between the PE non-woven fabric and the epoxy primer.

[0010] An adhesive and surface modification method for improving the adhesion between non-woven fabric and epoxy primer, wherein:

[0011] In the first aspect, an adhesive is prepared by pre-reacting oligomeric polyols, hydrophilic chain extenders and diisocyanates to form a prepolymer of a certain molecular weight, and then emulsifying the prepolymer in water and extending the chain thereafter by a phase transfer method, so that the adhesive system contains both polar and non-polar functional groups.

[0012] It includes: 50-200 parts of diol, 70-110 parts of diisocyanate, 15-25 parts of hydrophilic chain extender, 9-20 parts of neutralizer, 5-20 parts of post-chain extender, 1 part of catalyst, and 100 parts of water.

[0013] As an example, the diol is polypropylene glycol (PPG).

[0014] As an example, the diisocyanate is isophorone diisocyanate (IPDI).

[0015] As an example, the hydrophilic chain extender used is dimethylolpropionic acid (DMPA).

[0016] As an example, the chain extender is: ethylenediamine (EDA), a small molecule chain extender.

[0017] Secondly, a surface modification method for improving the adhesion of non-woven fabric to epoxy primer includes:

[0018] Step 1: Add one of surfactants A, a, b, and c to the prepared adhesive in the following mass ratio to obtain a modified adhesive;

[0019] As an example, surfactant A is a mixed solution of sodium fatty alcohol ether sulfate, sodium alkyl sulfonate, and water;

[0020] The surfactant a is: sodium fatty alcohol ether sulfate;

[0021] The surfactant b is: Tween 80;

[0022] The surfactant c is sodium dodecyl sulfate (SDS).

[0023] Step 2: Soak the laminate in ethanol for ultrasonic cleaning and then dry it.

[0024] As an example, ultrasonic cleaning with ethanol can effectively remove impurities from non-woven fabrics, preventing them from affecting subsequent adhesion.

[0025] As an example, ultrasonic cleaning is performed for 10 minutes, followed by drying at 60°C.

[0026] As an example, the laminate is a board made by pressing multiple layers of PE non-woven fabric.

[0027] Step 3: After uniformly coating the modified adhesive onto the surface of the laminate, apply a certain temperature to cure the modified adhesive at high temperature to obtain the modified laminate.

[0028] As an example, the coating refers to one or a combination of dropper coating, non-woven fabric wiping coating, or spray bottle spraying.

[0029] As an example, the "certain temperature" refers to a temperature between 150℃ and 160℃, and the high-temperature curing time is 10-30 seconds. Heating at high temperature for a certain time can cure the modified adhesive and effectively bond it to the polyolefin film on the surface of the laminate.

[0030] As an example, the high-temperature curing is performed using an electrically heated forced-air drying oven.

[0031] Step 4: Add a certain amount of graphene to the epoxy primer according to the mass ratio, stir with a high-speed homogenizer to mix the graphene and epoxy primer evenly, and obtain the modified epoxy primer.

[0032] As an example, the "certain mass of graphene" refers to graphene comprising 4% of the mass of the epoxy primer.

[0033] Step 5: Apply the modified epoxy primer evenly to the surface of the modified laminate to complete the bonding.

[0034] The beneficial effects of this invention are:

[0035] The waterborne polyurethane adhesive used in this invention has both polar and non-polar functional groups, which can interact with both non-polar PE nonwoven fabric and polar epoxy primer at the same time, thereby effectively improving the bonding force between the two.

[0036] This invention involves coating directly onto the surface of non-woven fabric materials, which simplifies the process and reduces implementation costs.

[0037] In this invention, graphene is added to the epoxy primer for modification, which can significantly improve the adhesion of the epoxy primer, resulting in a product with superior performance. Attached Figure Description

[0038] Figure 1 This is a hydrophilicity test diagram of a laminate coated with different modified adhesives, which is part of a surface modification method for improving the adhesion of non-woven fabric to epoxy primer according to the present invention.

[0039] in: Figure 1 'a' represents adhesive + surfactant A; Figure 1 b is the adhesive + surfactant a; Figure 1 c is adhesive + surfactant b; Figure 1 d represents adhesive + surfactant c; Figure 1 e represents the adhesive itself, without the addition of surfactants.

[0040] (The hydrophilicity test is to characterize whether the modified material surface can come into good contact with polar solvents. Epoxy primer itself is polar, and water is also a polar solution that is simple, readily available, and easy to operate. The first step in testing the affinity of the modified material for water is to make a preliminary judgment on the results of the modification.)

[0041] Figure 2 This is a comparison diagram showing the adhesion effects of laminates with different treatments to the primer in a surface modification method for improving the adhesion of non-woven fabric to epoxy primer according to the present invention.

[0042] in: Figure 2 a represents unmodified adhesive and epoxy primer without added graphene; Figure 2 b represents unmodified adhesive, with 4% graphene added to the epoxy primer by mass ratio; Figure 2 c represents adhesive modification; the epoxy primer did not contain graphene. Figure 2 d represents adhesive modification, with 4% graphene added to the epoxy primer by mass ratio. Detailed Implementation

[0043] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application. Figures 1 to 2 As shown:

[0044] An adhesive and surface modification method for improving the adhesion between non-woven fabric and epoxy primer, wherein:

[0045] In the first aspect, an adhesive is prepared by pre-reacting oligomeric polyols, hydrophilic chain extenders and diisocyanates to form a prepolymer of a certain molecular weight, and then emulsifying the prepolymer in water and extending the chain thereafter by a phase transfer method, so that the adhesive system contains both polar and non-polar functional groups.

[0046] It includes: 50-200 parts of diol, 70-110 parts of diisocyanate, 15-25 parts of hydrophilic chain extender, 9-20 parts of neutralizer, 5-20 parts of post-chain extender, 1 part of catalyst, and 100 parts of water.

[0047] As an example, the diol is polypropylene glycol (PPG).

[0048] As an example, the diisocyanate is isophorone diisocyanate (IPDI).

[0049] As an example, the hydrophilic chain extender used is dimethylolpropionic acid (DMPA).

[0050] As an example, the chain extender is: ethylenediamine (EDA), a small molecule chain extender.

[0051] Secondly, a surface modification method for improving the adhesion of non-woven fabric to epoxy primer includes:

[0052] Step 1: Add one of surfactants A, a, b, and c to the prepared adhesive in the following mass ratio to obtain a modified adhesive;

[0053] As an example, surfactant A is a mixed solution of sodium fatty alcohol ether sulfate, sodium alkyl sulfonate, and water;

[0054] The surfactant a is: sodium fatty alcohol ether sulfate;

[0055] The surfactant b is: Tween 80;

[0056] The surfactant c is sodium dodecyl sulfate (SDS).

[0057] Step 2: Soak the laminate in ethanol for ultrasonic cleaning and then dry it.

[0058] As an example, ultrasonic cleaning with ethanol can effectively remove impurities from non-woven fabrics, preventing them from affecting subsequent adhesion.

[0059] As an example, ultrasonic cleaning is performed for 10 minutes, followed by drying at 60°C.

[0060] As an example, the laminate is a board made by pressing multiple layers of PE non-woven fabric.

[0061] Step 3: After uniformly coating the modified adhesive onto the surface of the laminate, apply a certain temperature to cure the modified adhesive at high temperature to obtain the modified laminate.

[0062] As an example, the coating refers to one or a combination of dropper coating, non-woven fabric wiping coating, or spray bottle spraying.

[0063] As an example, the "certain temperature" refers to a temperature between 150℃ and 160℃, and the high-temperature curing time is 10-30 seconds. Heating at high temperature for a certain time can cure the modified adhesive and effectively bond it to the polyolefin film on the surface of the laminate.

[0064] As an example, the high-temperature curing is performed using an electrically heated forced-air drying oven.

[0065] Step 4: Add a certain amount of graphene to the epoxy primer according to the mass ratio, stir with a high-speed homogenizer to mix the graphene and epoxy primer evenly, and obtain the modified epoxy primer.

[0066] As an example, the "certain mass of graphene" refers to graphene comprising 4% of the mass of the epoxy primer.

[0067] Step 5: Apply the modified epoxy primer evenly to the surface of the modified laminate to complete the bonding.

[0068] To better illustrate the design principles of this invention, specific embodiments are provided below:

[0069] Example 1:

[0070] Modified adhesive: Synthetic adhesive 1 (i.e., pre-reacting oligomeric polyols, hydrophilic chain extenders and diisocyanates to prepare a prepolymer of a certain molecular weight, then emulsifying the prepolymer in water and extending the chain using a phase transfer method, so that the adhesive system contains both polar and non-polar functional groups); , surfactant A is added at a mass ratio of 5%, and the mixture is uniformly mixed to obtain modified adhesive 1-A.

[0071] Laminate modification includes the following steps:

[0072] The S1 laminate is immersed in an ethanol solution, ultrasonically treated for 10 minutes, and then dried at 60°C for later use.

[0073] S2 uses a dropper to draw modified adhesive 1-A and adds it to the laminate. Spread the liquid evenly to flatten the droplet, and stand the laminate upright to allow excess liquid to drip off and be removed.

[0074] S3 places the laminated board coated with adhesive into an electric heating drying oven and heats it at 150°C for 20 seconds to cure it.

[0075] After the laminate is cured at high temperature (S4) and cooled naturally, an epoxy primer containing 4% (by mass) graphene is applied to the surface. The primer is then allowed to air dry or heated at 80°C for 2 hours to dry.

[0076] Adhesion testing was conducted according to the standard GB / T 9286-1998 Paints and Varnishes - Cross-cut Test for Coatings.

[0077] The degree of primer peeling is less than 5%.

[0078] Examples 2-5:

[0079] Modified adhesive: Synthetic adhesive 1 was mixed with surfactant A at mass ratios of 4% (i.e., Example 2), 3% (i.e., Example 3), 2% (i.e., Example 4), and 1% (i.e., Example 5) to obtain modified adhesive 1-A.

[0080] The laminate modification process includes the same steps as in Example 1.

[0081] Examples 6-8:

[0082] Modified adhesives: Synthetic adhesive 1 is mixed with surfactant a (Example 6), or b (Example 7), or c (Example 8) at a mass ratio of 5%, and the mixture is uniformly mixed to obtain modified adhesives 1-a, 1-b, and 1-c respectively.

[0083] The laminate modification process includes the same steps as in Example 1.

[0084] Examples 9-11:

[0085] Modified adhesive: Synthetic adhesive 1 is mixed with surfactant A at a mass ratio of 5% to obtain modified adhesive 1-A.

[0086] The laminate modification was carried out using the steps S1 and S2 of Example 1. The high-temperature curing adhesive was applied at 150°C for 10 seconds (Example 9), 150°C for 30 seconds (Example 10), and 160°C for 20 seconds (Example 11). The epoxy primer was then applied, and the adhesion test was performed according to step S4 of Example 1.

[0087] Examples 12-13:

[0088] Modified adhesive: Synthetic adhesive 1 is mixed with surfactant A at a mass ratio of 5% to obtain modified adhesive 1-A.

[0089] Laminate modification: After ultrasonic cleaning of the laminate with ethanol, the modified adhesive 1-A is applied to the surface of the laminate using a non-woven fabric. Then, the adhesive is cured at high temperature according to steps S3 and S4 in Example 1 and an epoxy primer is applied.

[0090] The results of all the above embodiments are shown in Table 1.

[0091] Table 1. Statistical Table of Experimental Conditions and Adhesion Results for Each Example

[0092]

[0093]

[0094] To better illustrate the beneficial effects and advancements of this invention, comparative examples and case data are used to further verify the results. Adhesion tests were conducted according to the GB / T 9286-1998 standard for cross-cut adhesion tests of paints and varnishes.

[0095] Comparative Example 1:

[0096] After ultrasonic cleaning with ethanol, the laminate was coated directly with a graphene-free epoxy primer without any modification treatment, and the adhesion was tested.

[0097] At this point, 98% of the epoxy primer had peeled off.

[0098] Comparative Example 2:

[0099] After ultrasonic cleaning with ethanol, the laminate was coated with an epoxy primer containing 4% graphene without any modification treatment, and its adhesion was tested.

[0100] At this point, 96% of the epoxy primer had peeled off.

[0101] Comparative Example 3:

[0102] After ultrasonic cleaning with ethanol, the laminate was treated with modified adhesive 1-A, coated with a graphene-free epoxy primer, and its adhesion was tested.

[0103] At this point, 45% of the epoxy primer has peeled off.

[0104] Comparative Example 4:

[0105] After ultrasonic cleaning with ethanol, the laminate was treated with modified adhesive 1-A, coated with an epoxy primer containing 4% graphene, and its adhesion was tested.

[0106] At this point, the epoxy primer peeling rate is less than 5%.

[0107] It should be noted that, for the sake of simplicity, the method embodiments are all described as a series of actions. However, those skilled in the art should understand that this application is not limited to the described order of actions, because according to this application, some steps can be performed in other orders or simultaneously. Secondly, those skilled in the art should also understand that the embodiments described in the specification are all optional embodiments, and the actions involved are not necessarily required by this application.

[0108] The above description is only a preferred embodiment of the present invention. It should be understood that the above description of the embodiments is only for the purpose of helping to understand the method and core idea of ​​the present invention, and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, etc. made within the idea and principle of the present invention should be included within the scope of protection of the present invention.

Claims

1. An adhesive, characterized in that, A prepolymer of a certain molecular weight is prepared by pre-reacting oligomeric polyols, hydrophilic chain extenders and diisocyanates. The prepolymer is then emulsified in water and chain extended using a phase transfer method, so that the adhesive system contains both polar and non-polar functional groups. It includes: 50-200 parts of diol, 70-110 parts of diisocyanate, 15-25 parts of hydrophilic chain extender, 9-20 parts of neutralizer, 5-20 parts of post-chain extender, 1 part of catalyst, and 100 parts of water.

2. The adhesive according to claim 1, characterized in that, The diol is polypropylene glycol; the diisocyanate is isophorone diisocyanate; the hydrophilic chain extender is dimethylolpropionic acid; and the post-chain extender is ethylenediamine, a small molecule post-chain extender.

3. A surface modification method for improving the adhesion of non-woven fabric to epoxy primer, characterized in that, include: Step 1: Add one of surfactants A, a, b, and c to the prepared adhesive in the following mass ratio to obtain a modified adhesive; The surfactant A is a mixed solution of sodium fatty alcohol ether sulfate, sodium alkyl sulfonate, and water; The surfactant a is: sodium fatty alcohol ether sulfate; The surfactant b is: Tween 80; The surfactant c is sodium dodecyl sulfate; Step 2: Soak the laminate in ethanol for ultrasonic cleaning and then dry it. Step 3: After uniformly coating the modified adhesive onto the surface of the laminate, apply a certain temperature to cure the modified adhesive at high temperature to obtain the modified laminate. Step 4: Add a certain amount of graphene to the epoxy primer according to the mass ratio, stir with a high-speed homogenizer to mix the graphene and epoxy primer evenly, and obtain the modified epoxy primer. Step 5: Apply the modified epoxy primer evenly to the surface of the modified laminate to complete the bonding.

4. The surface modification method for improving the adhesion of non-woven fabric to epoxy primer according to claim 3, characterized in that, The sample was ultrasonically cleaned with ethanol for 10 minutes and then dried at 60°C.

5. The surface modification method for improving the adhesion of non-woven fabric to epoxy primer according to claim 3, characterized in that, The laminate is a board made of multiple layers of PE non-woven fabric.

6. The surface modification method for improving the adhesion of non-woven fabric to epoxy primer according to claim 3, characterized in that, The coating refers to one of the following: dropper coating, non-woven fabric wiping coating, or spray bottle spraying coating.

7. The surface modification method for improving the adhesion of non-woven fabric to epoxy primer according to claim 3, characterized in that, The specified temperature refers to a temperature between 150℃ and 160℃, and the high-temperature curing time is 10-30 seconds. Heating at high temperature for a certain time can cure the modified adhesive and effectively bond it to the polyolefin film on the surface of the laminate.

8. The surface modification method for improving the adhesion of non-woven fabric to epoxy primer according to claim 3, characterized in that, The high-temperature curing is performed using an electric heating forced-air drying oven.

9. The surface modification method for improving the adhesion of non-woven fabric to epoxy primer according to claim 3, characterized in that, The specified amount of graphene refers to graphene comprising 4% of the mass of the epoxy primer.

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