Preparation method of resin adhesive film with uniformly distributed resin content

Abstract

The invention relates to a preparation method of a resin adhesive film with uniform resin content distribution. According to the method, a hot melt adhesive film method is adopted for preparing a resin adhesive film, a first steel roller and a second steel roller of gluing equipment are controlled to rotate at the same time in opposite rotation directions, the two steel rollers extrude particles with large particle sizes in a resin matrix and take out the particles, and meanwhile release paper is coated with the resin matrix to form the resin adhesive film; the rotation direction of the first steel roller is the anticlockwise direction, and the rotation direction of the second steel roller is the clockwise direction. According to the preparation method, the technological process of preparing the resin adhesive film required by the prepreg by a hot melt adhesive film method is optimized, the problems of lack of adhesive lines and non-uniform resin content distribution in the film coating process of the resin matrix can be effectively solved, and the stability of the surface density of the resin adhesive film is greatly improved; and thus, the performance of the prepreg and subsequent composite material products thereof can be improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of fiber-reinforced resin materials, and specifically relates to a preparation method of a resin film and a fiber-reinforced prepreg. Background Art

[0002] Fiber resin prepregs are widely used in the fields of aerospace, automotive, shipbuilding, etc. due to their excellent mechanical properties, chemical corrosion resistance, and good heat resistance. During the preparation process of fiber resin prepregs, fiber reinforcement materials and matrix resins are usually pressed together at a certain temperature through processes such as mechanical pressing, and then through processes such as cloth cutting, layering, and curing, composite products with high strength, high stiffness, and low density are prepared.

[0003] The existing preparation methods of prepregs mainly include: solution impregnation method and hot melt adhesive film method. Among them, the solution impregnation method has gradually been replaced by the hot melt adhesive film method due to the difficulty in precisely controlling the resin content during the preparation process and problems such as environmental pollution. The hot melt adhesive film method is to first reduce the resin viscosity of the matrix resin at a certain temperature, prepare a resin film through a coating device, and then laminate and impregnate the reinforcing fiber with the film to prepare a composite prepreg. The prepreg prepared by this process has less volatile matter and no environmental pollution.

[0004] The existing resin film preparation equipment coats the resin by controlling the rotation of the coating steel roller, and prepares the resin film by setting an appropriate ratio of the steel roller gap and the rotation speed of the steel roller to the running speed of the release paper. There are two specific coating methods, as Figure 1 、 Figure 2 shown, where Figure 1 is the forward coating method, and Figure 2 is the reverse coating method. During the forward coating process shown in Figure 1 , the resin matrix 6 is added between the two steel rollers. The first steel roller 1 does not rotate, and through the rotation of the second steel roller 2 and the rubber roller 3, the resin is coated on the release paper 4 to form a resin film 5. During the reverse coating process shown in Figure 2 , both the first steel roller 1 and the second steel roller 2 rotate, and the rotation directions are the same (both clockwise). A rubber roller 3 is provided below each of the first steel roller 1 and the second steel roller 2. The first steel roller 1 and the second steel roller 2 jointly coat the resin on the release paper 4 to form a resin film 5. Among them, during the forward coating process, if the first steel roller also rotates, the resin will remain on the surface of the steel roller, causing resin waste and requiring additional scrubbing work. Moreover, the rotation mode of the first steel roller will have a certain impact on the areal density of the resin film. Therefore, the first steel roller does not rotate during the forward coating process.

[0005] The main deficiencies of the hot melt adhesive film method in the process of preparing the resin adhesive film required for prepreg are as follows: The existing preparation methods have high requirements for the performance of the matrix resin itself. When the particle size of the particulate matter (some solid particulate matter formed during the resin synthesis process) in the matrix resin is large and the resin viscosity is low, when using Figure 1 the coating equipment shown in the figure to prepare the adhesive film by the forward coating method, when the gap between the coating steel rollers (i.e., the gap between the first steel roller and the second steel roller) is small, it causes the particulate matter with a large particle size in the resin to get stuck in the gap between the steel rollers during the rotation of the steel rollers, resulting in the occasional appearance of a certain degree of glue shortage line in the resin adhesive film, and further causing uneven distribution of the resin in this part of the resin adhesive film, affecting the coating uniformity of the resin adhesive film, as well as the material properties of the subsequent prepreg product and the non-destructive and mechanical properties of its composite material. If the way of increasing the gap between the steel rollers is adopted, it is easy to cause excessive resin to flow out from the gap between the steel rollers, thus affecting the stability of the surface density of the resin adhesive film. Summary of the Invention

[0006] Aiming at the problem of uneven resin content distribution caused by the appearance of glue shortage lines in the resin adhesive film required for the existing prepreg, the present invention provides a process method for optimizing the preparation of the resin adhesive film.

[0007] The solution adopted by the present invention to solve this problem is as follows:

[0008] A method for preparing a resin adhesive film with uniform resin content distribution, which uses the hot melt adhesive film method to prepare the resin adhesive film. The method includes the following steps:

[0009] Add a resin matrix between the first steel roller and the second steel roller of the coating equipment;

[0010] Control the first steel roller and the second steel roller of the coating equipment to rotate simultaneously and in opposite directions. The two steel rollers squeeze the particulate matter with a large particle size in the resin matrix and take out the particulate matter, while the resin matrix is coated on the release paper to form a resin adhesive film.

[0011] Further, the rotation direction of the first steel roller is counterclockwise, and the rotation direction of the second steel roller is clockwise.

[0012] Further, the rotation speed of the first steel roller is ≤10 rpm, and the rotation speed of the second steel roller is 30 - 80 rpm.

[0013] Further, before adding the resin matrix between the two steel rollers of the coating equipment, it also includes: determining the production parameters of the glue melting equipment according to the rheological curve and gel time of the resin.

[0014] Further, before adding the resin matrix between the two steel rollers of the coating equipment, it also includes: determining the production parameters of the coating equipment according to the required surface density and width of the resin adhesive film.

[0015] Further, before adding the resin matrix between two steel rollers of the gluing device, it further includes threading the release paper and PE film through the gluing device and melting the matrix resin.

[0016] Further, wind up the resin film and take samples for the uniformity test of the resin film to ensure that the distribution of the resin in the resin film meets the production requirements.

[0017] Further, the uniformity test of the resin film includes: preparing a resin film with an appropriate length, taking samples at a fixed distance interval and testing its areal density, and using the coefficient of variation of all test samples to characterize the stability of the areal density of the resin film, thereby illustrating the uniformity of the resin film.

[0018] Further, the resin film prepared has a width of 350 mm and a length of 50 m. Samples are taken every 5 m, and the areal density of the resin film is tested by the weighing method. The sample size is 100 mm * 100 mm, and the areal density data is statistically analyzed and the corresponding coefficient of variation is calculated.

[0019] The present invention also provides a resin film with a uniform resin content distribution prepared according to the method of the present invention described above.

[0020] The beneficial effects of the present invention are as follows:

[0021] The present invention optimizes the process flow of the resin film required for preparing prepregs by the hot melt film method. Under the condition of keeping other conditions unchanged, by controlling the relative rotation of two gluing steel rollers, the situation of lack of glue line and the problem of uneven resin content distribution during the coating process of the resin matrix can be effectively solved, the stability of the areal density of the resin film is greatly improved, and further the performance of prepregs and their subsequent composite products can be improved. Description of the Drawings

[0022] Figure 1 It is a schematic diagram of the forward coating method of the resin film preparation device.

[0023] Figure 2 It is a schematic diagram of the reverse coating method of the resin film preparation device.

[0024] Figure 3 It is a schematic diagram of the rotation direction of the steel roller of the resin film preparation device of the present invention. Detailed Embodiments

[0025] In order to more clearly show the technical problems, technical solutions and beneficial effects solved by the present invention, the present invention will be further described in detail below in combination with examples and comparative examples.

[0026] The present invention provides an optimized process method for preparing a resin film, that is, a method for preparing a resin film with a uniform resin content distribution, including the following steps:

[0027] 1. Determine the parameters such as the temperature and time for melting the resin and the production speed of the coating equipment according to the rheological curve and gel time of the corresponding resin and other parameters.

[0028] 2. Determine the appropriate adjustment gap of the steel roller and the appropriate production parameters such as speed difference and width according to the requirements such as the surface density and width of the required resin film. The speed difference refers to the ratio of the running speed of the release paper to the rotation speed of the second steel roller during the production process and can be adjusted. The width refers to the width of the required resin film for production and can be freely adjusted.

[0029] 3. After determining the production parameters, thread the release paper and the PE film, start the production equipment, set the production parameters, and melt the matrix resin (i.e., heat and melt).

[0030] 4. After the parameters are stably operating, add the corresponding matrix resin between the coating steel rollers. After the resin is evenly distributed between the steel rollers, operate the coating equipment to prepare the resin film. The resin film is prepared on the release paper, and the PE film covers the resin film. The release paper and the PE film are used to separate different layers of the resin film when forming the resin film coil to prevent them from sticking to each other.

[0031] 5. During the rotation of the coating steel rollers, since the resin adding area is the area generated by the closing of two metal steel rollers, the resin film is formed by the rotation of the two metal steel rollers. Preferably, control the relative rotation speed of the two steel rollers to be constant, ensure the preparation parameters of the resin film, and adjust to the two steel rollers rotating simultaneously and in opposite directions. As Figure 3 shown, the rotation direction of the first steel roller 1 is counterclockwise, and the rotation direction of the second steel roller 2 is clockwise. Through the rotation of the second steel roller 2 and the rubber roller 3, the resin is coated on the release paper 4 to form the resin film 5. In this way, the first steel roller 1 and the second steel roller 2 can effectively carry out the larger particle size particles in the resin matrix in a squeezing form, thereby reducing the situation of lack of glue lines in the resin film caused by the particles, greatly improving the resin distribution uniformity of the resin film, and further improving the properties of the prepreg and its composite products.

[0032] Among them, the main influencing factor of the coating amount is not the rotation of the first steel roller. The main function of the rotation of the first steel roller is to drive the discharge of the particles, prevent the generation of lack of glue lines, and in order to reduce the waste of resin, it is necessary to adjust the first steel roller to rotate at a lower speed.

[0033] Preferably, the present invention controls Figure 1The rotation speed of the first steel roller is ≤10 rpm, and the rotation speed of the second steel roller is 30 - 80 rpm.

[0034] 6. Wind up the semi-finished resin film, and take samples for testing to ensure that the resin distribution of the film product meets the production requirements.

[0035] 7. Uniformity test of the resin film: Prepare a resin film of appropriate length, take samples at fixed intervals to test its areal density, and use the coefficient of variation of all test sample data to characterize the stability of the areal density of the resin film, thereby indicating the uniformity of the resin film. Preferably, the prepared resin film has a width of 350 mm and a length of 50 m, samples are taken every 5 m, the areal density of the resin film is tested by the weighing method, the sample size is 100 mm * 100 mm, the data is statistically analyzed and the corresponding coefficient of variation is calculated.

[0036] Example 1:

[0037] (1) Use epoxy resin as the resin matrix to prepare a resin film with a width of 300 - 500 mm and a target areal density of 30 - 60 g / m 2 ; (2) Determine the corresponding temperature during the preparation process according to the rheological curve and gel time and other performance parameters of the used epoxy resin, determine the corresponding production gap (the gap between the steel rollers), speed difference (the ratio of the running speed of the release paper to the rotation speed of the second steel roller), etc. according to the target areal density and width and other parameters, and keep them unchanged during the production process. The production parameters of this example are the same as those of Comparative Example 1; (3) Set the rotation speed of the second steel roller for coating to 70 rpm, and the rotation speed of the first steel roller for coating to 10 rpm. The inner and outer diameters of the two steel rollers are the same. (4) During the production process of the resin film, take samples of the areal density every 5 meters, statistically analyze the test data, and observe the product performance stability.

[0038] Example 2:

[0039] (1) Use bismaleimide resin as the resin matrix to prepare a resin film with a width of 300 - 500 mm and a target areal density of 30 - 60 g / m 2 ; (2) Determine the corresponding temperature during the preparation process according to the rheological curve and gel time and other performance parameters of the used epoxy resin, determine the corresponding production gap, speed, speed difference, etc. according to the target areal density and width and other parameters, and keep them unchanged during the production process. The production parameters of this example are the same as those of Comparative Example 2; (3) Set the rotation speed of the second steel roller for coating to 70 rpm, and the rotation speed of the first steel roller for coating to 10 rpm. The inner and outer diameters of the two steel rollers are the same. (4) During the production process of the resin film, take samples of the areal density every 5 meters, statistically analyze the test data, and observe the product performance stability.

[0040] Example 3:

[0041] (1) Use cyanate resin as the resin matrix to prepare a resin film with a width of 300 - 500 mm and a target areal density of 30 - 60 g / m 2 ; (2) Determine the corresponding temperature during the preparation process according to the rheological curve and gel time of the epoxy resin used, and determine the corresponding production gap, speed, speed difference, etc. according to parameters such as the target areal density and width, and keep them unchanged during the production process. The production parameters of this example are the same as those of Comparative Example 3; (3) Set the rotational speed of the second coating steel roller at 70 rpm and the rotational speed of the first coating steel roller at 10 rpm. The inner and outer diameters of the two steel rollers are the same. (4) During the production process of the resin film, take areal density samples for testing every 5 meters, and count the test data to observe the product performance stability.

[0042] Comparative Example 1:

[0043] (1) Use epoxy resin as the resin matrix to prepare a resin film with a width of 300 - 500 mm and a target areal density of 30 - 60 g / m 2 ; (2) Determine the corresponding temperature during the preparation process according to the rheological curve and gel time of the epoxy resin used, and determine the corresponding production gap, speed, speed difference, etc. according to parameters such as the target areal density and width, and keep them unchanged during the production process; (3) Set the rotational speed of the second coating steel roller at 60 rpm and the rotational speed of the first coating steel roller at 0 rpm. The inner and outer diameters of the two steel rollers are the same. (4) During the production process of the resin film, take areal density samples for testing every 5 meters, and count the test data to observe the product performance stability.

[0044] Comparative Example 2:

[0045] (1) Use bismaleimide resin as the resin matrix to prepare a resin film with a width of 300 - 500 mm and a target areal density of 30 - 60 g / m 2 ; (2) Determine the corresponding temperature during the preparation process according to the rheological curve and gel time of the epoxy resin used, and determine the corresponding production gap, speed, speed difference, etc. according to parameters such as the target areal density and width, and keep them unchanged during the production process; (3) Set the rotational speed of the second coating steel roller at 60 rpm and the rotational speed of the first coating steel roller at 0 rpm. The inner and outer diameters of the two steel rollers are the same. (4) During the production process of the resin film, take areal density samples for testing every 5 meters, and count the test data to observe the product performance stability.

[0046] Comparative Example 3:

[0047] (1) Use cyanate resin as the resin matrix to prepare a resin film with a width of 300 - 500 mm and a target areal density of 30 - 60 g / m 2The resin adhesive film; (2) Determine the corresponding temperature during the preparation process according to the rheological curve and gel time and other performance parameters of the epoxy resin used, and determine the corresponding production gap, speed, speed difference and other parameters according to the target areal density and width and other parameters, and keep them unchanged during the production process; (3) Set the rotation speed of the second coating steel roller to 60 rpm, and the rotation speed of the first coating steel roller to 0 rpm. The inner and outer diameters of the two steel rollers are the same. (4) During the production process of the resin adhesive film, take areal density samples every 5 meters for testing, and count the test data to observe the product performance stability.

[0048] For the resin adhesive film prepared above, conduct areal density testing and data statistics. The areal density data and the calculation results of the coefficient of variation are shown in Table 1.

[0049] Table 1 Test results of fiber areal density

[0050]

[0051] It can be seen from the test results in Table 1 that:

[0052] 1) Compared with the control example, the average value of the areal density of the resin adhesive film in the three groups of examples is higher. This is because when the two coating steel rollers rotate simultaneously, some particulate matters in the glue tank will be carried out, effectively reducing the obstructive effect of the particulate matters on the resin coating film.

[0053] 2) By comparing the coefficients of variation of the examples and the control example, it can be seen that the coefficients of variation of the three groups of data in the examples are smaller than those of the three groups of data in the control example. This is because the obstructive effect of the particulate matters on the resin coating film is reduced, and the resin matrix can be coated more stably. Especially in Control Example 1 and Control Example 3, visible glue shortage lines appeared on the resin adhesive film, resulting in large fluctuations in the areal density data and significantly larger coefficients of variation.

[0054] In summary, under the condition of keeping other conditions unchanged, by controlling the relative rotation of the two coating steel rollers, the situation of glue shortage lines appearing during the coating process of the resin matrix can be effectively solved, and the stability of the areal density of the resin adhesive film can be greatly improved.

[0055] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, and improvements made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for preparing a resin film with uniform resin content distribution, characterized in that, the hot melt film method is used to prepare the resin film, and this method includes the following steps: Add a resin matrix between the first steel roller and the second steel roller of the coating equipment; Control the first steel roller and the second steel roller of the coating equipment to rotate simultaneously and in opposite directions. The two steel rollers extrude the larger particles in the resin matrix and take out the particles, while the resin matrix is coated on the release paper to form a resin film.

2. The method according to claim 1, characterized in that, the rotation direction of the first steel roller is counterclockwise, and the rotation direction of the second steel roller is clockwise.

3. The method according to claim 2, characterized in that, the rotation speed of the first steel roller is ≤ 10 rpm, and the rotation speed of the second steel roller is 30 - 80 rpm.

4. The method according to claim 1, characterized in that, before adding the resin matrix between the two steel rollers of the coating equipment, it further includes: determining the melting temperature, time and the production speed of the coating equipment according to the rheological curve and gel time of the resin.

5. The method according to claim 1, characterized in that, before adding the resin matrix between the two steel rollers of the coating equipment, it further includes: determining the steel roller gap, speed difference and width of the coating equipment according to the required surface density and width of the resin film.

6. The method according to claim 1, characterized in that, before adding the resin matrix between the two steel rollers of the coating equipment, it further includes: threading the release paper and PE film through the coating equipment, and melting the matrix resin.

7. The method according to claim 1, characterized in that, wind up the resin film and take samples for the uniformity test of the resin film to ensure that the resin distribution in the resin film meets the production requirements.

8. The method according to claim 7, characterized in that, the uniformity test of the resin film includes: preparing a resin film with an appropriate length, sampling at a fixed distance at intervals and testing its surface density, and using the coefficient of variation of all test samples to characterize the stability of the surface density of the resin film, thereby indicating the uniformity of the resin film.

9. The method according to claim 8, characterized in that, the width of the prepared resin film is 350 mm, the length is 50 m, sampling is carried out every 5 m, the surface density of the resin film is tested by the weighing method, the sample size is 100 mm * 100 mm, and the surface density data is statistically analyzed and the corresponding coefficient of variation is calculated.

10. A resin film with uniform resin content distribution prepared by the method according to any one of claims 1 - 9.

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