JP6735500B2 - Evaluation method of resin impregnating ability of glass fiber for resin molding - Google Patents

Description

The present invention relates to a method for evaluating resin impregnating ability of glass fibers for resin molded products.

BACKGROUND ART It has been conventionally known to produce a resin molded product by using SMC (Sheet Molding Compounds) obtained by mixing a thermosetting resin composition and glass fiber and molding the mixture into a sheet. The resin molded product from SMC is widely used for bathtubs, washbasins, kitchen counters, etc. because it has both design and strength.

The SMC is produced, for example, as glass fibers by cutting a glass roving 41 into an appropriate length and mixing the chopped strands with a resin composition as shown in FIG. ing. Here, the glass roving 41 is made of a bundle of a plurality of glass fibers called a glass strand 42 having a certain length or more, and each glass strand 42 is a glass monofilament which is a minimum unit. 43 is formed by binding with a binder 44.

In the resin molded product from SMC containing such glass fiber, the strength as a composite material is obtained by the bonding of the cured resin composition and the glass fiber. However, in order for the resin molded product to have appropriate strength and to have an excellent surface appearance, the resin impregnation property of the glass fiber is excellent, and the glass fiber is impregnated with an appropriate amount of the resin composition. Is required.

It has been attempted to evaluate the impregnating ability of the glass fiber with the resin from various viewpoints and methods.

For example, for a prepreg in the area of a printed wiring board, a method of evaluating the resin impregnating ability of glass fibers by observing voids, which are areas in which the resin impregnating ability of glass fibers is lowered, has been proposed (Patent Reference 1).

In the evaluation method of resin impregnation property of glass fiber described in Patent Document 1, a prepreg is arranged between a light source and a camera, light is emitted from below the prepreg by the light source, and transmitted light transmitted through the prepreg is measured by the camera. Take an image with. It is said that the obtained image can be binarized to identify the presence or absence of a void and the position of the void based on the data indicating the bright and dark areas on the prepreg surface. That is, in the above evaluation method, in the void-free portion, or in the central portion of the cylindrical void, the light perpendicularly incident on the prepreg from the light source goes straight and is displayed brightly, but in the surface portion of the void, Light perpendicularly incident on the prepreg from the light source is refracted and scattered, and is displayed dark. Such an image is binarized to calculate the void area, and when the total area is smaller than a predetermined threshold value, it is determined that the resin impregnation property of the glass fiber is good.

However, the problem of voids in the above prepreg is that it causes a decrease in electrical insulation, and the detection of voids and the evaluation of the resin impregnation property into glass fibers are not always directly related. There wasn't. In the prepreg, the strength, which is important in the production of resin molded products using SMC, and the design characteristics such as the appearance of the surface after molding and curing are not considered at all.

JP, 2006-64531, A

The present invention has been made in view of the circumstances as described above, it is possible to obtain a resin molded product that exhibits appropriate strength and also has an excellent aesthetic appearance of the surface, and a glass fiber having excellent resin impregnation properties. An object of the present invention is to provide a selectable evaluation method of resin impregnating properties of glass fibers for resin molded products.

In order to solve the above problems, the present inventor has studied in detail the step of impregnating the glass fiber with the resin composition. Therefore, it should be noted that in order for the resin molded product to exhibit appropriate strength and also to have an excellent surface aesthetics, a binder that binds the glass monofilaments in the glass fiber to each other. It is required that the resin composition be appropriately impregnated into the glass monofilament by dissolving the resin. In the impregnation step, the glass fiber is impregnated with the resin composition, passing through the glass strands, and passing through the process of wet-through, the solvent component in the resin composition binds the monofilaments to each other. Melt, wet out happens. When glass fibers having a fast wet-out are used, a resin molded product having an excellent appearance can be obtained without leaving undispersed glass strands in the cured resin molded product. On the other hand, if the wet-out is too early, the glass fiber, by the time the resin composition reaches the center of the glass fiber mat, the solvent component is consumed, the glass fiber that has not been wet-out remains, and it is said that it is not impregnated. .. When the unimpregnated glass fiber remains, an unsatisfactory appearance in which undispersed glass strands are raised on the surface of the resin molded product is caused. Further, since a portion where the resin composition and the glass fiber are not in close contact with each other is generated, a problem such as a desired strength not being exhibited occurs.

It is considered that using such a wet-out ratio as an index is effective in evaluating the resin impregnation property of the glass fiber.

Therefore, the inventors of the present invention, the binder of the glass fiber, optically observe the change when dissolved by the solvent component in the resin composition, and quantitatively the area of the wet-out region relative to the area of the entire glass fiber. Focusing on the evaluation, the present invention has been completed.

The method for evaluating the resin impregnating property of the glass fiber for a resin molded article of the present invention is a method for evaluating a glass fiber in which a glass monofilament is adhered by a binder, which is used for a resin molded article obtained by molding a resin composition, A step of placing a glass fiber on a substrate having a lightness L value of 0 or more and 70 or less to image the glass fiber and the substrate, and the glass fiber in the image obtained by the imaging in the imaging step. And a step of calculating the area S _{0 of} the region corresponding to, and the glass fiber by supplying the resin composition or a partial component thereof to the glass fiber and supplying the resin composition at the same position as the step. Lightness L of the step of imaging with time, the area corresponding to the substrate in the image obtained by imaging in the step of imaging with time, and the area corresponding to the glass fiber after the resin composition is supplied. Comparing the values and calculating the area S ₁ of the wet-out area in which the difference in lightness L value is smaller than a predetermined value of 30 or less with time; and the area S ₀ of the area corresponding to the glass fiber. Calculating the area ratio of the area S ₁ of the wet-out region over time.

According to the method for evaluating the resin impregnating ability of the glass fiber for a resin molded product of the present invention, it is possible to select a glass fiber that can obtain a resin molded product that exhibits appropriate strength and has an excellent surface appearance.

It is the schematic which illustrated the embodiment of this invention. (A) (b) (c) (d) is a figure which showed the mode that the wet-out of glass fiber advances. It is a block diagram which shows the process of evaluating the resin impregnation property of glass fiber. It is the schematic which showed typically the structure of the glass fiber for resin moldings.

Hereinafter, a method for evaluating the resin impregnating ability of the glass fiber for resin molded product of the present invention will be described in detail.

FIG. 1 shows an example of an image measurement system used in the embodiment of the present invention. This image measuring system includes a camera 1 and an image processing device 2. As the camera 1, a camera using a semiconductor device such as a CCD camera can be used. A computer (electronic computer) can be used as the image processing apparatus 2.

The glass fiber 4 to be evaluated for the resin impregnating property is placed on the substrate 3 having a lightness L value of 0 or more and 70 or less.

The glass fiber 4 here is a glass fiber formed by bonding a glass monofilament 43 with a binder 44, as shown in FIG. In the glass fiber 4, a large number of colorless and transparent glass monofilaments 43 are bound by a binder 44 having low transparency. Therefore, the glass fiber 4 often has a milky white appearance until it is mixed with the resin composition 5 described later.

The binder 44 is not particularly limited as long as it is a resin that can be dissolved by the solvent component in the resin composition 5 used in the production of SMC and its molded article described below, and examples thereof include acrylic resin, epoxy resin, urethane resin and the like. It is illustrated. The resin used as the binder 44 may be the same as or different from the resin which is the main component of the resin composition 5 used in the production of SMC and its molded article, but it may be the same kind of resin. It is preferably considered to be a resin.

As the glass fibers 4, commercially available glass rovings for SMC molding, glass fiber mats, chop strands and the like can be preferably used. For example, SMC molding glass roving RS 480-550 (manufactured by Nitto Boseki), which is preferably used for manufacturing bathtubs, SMC molding glass roving RS 460 A-782 (manufactured by Nitto Boseki), which is preferably used for automobile bodies and the like. Etc. are illustrated.

The base 3 is a flat plate on which the glass fiber 4 to be evaluated is placed.

The color tone of the base body 3 is not particularly limited as long as the value of the lightness L value is within the above range. For example, in addition to black, the tone of the lightness L value is 0 to 70, such as gray, red and blue. A substrate exhibiting a color tone of can be used, and a black substrate can be preferably used.

The lightness L value as used herein is an index representing lightness in the L ^* a ^* b ^* color system, and can take a numerical value from 0 to 100. When the lightness L value approaches 0, the lightness decreases and the color tone darkens. When the lightness L value approaches 100, the lightness increases and the color tone brightens. When the lightness L value exceeds 70, the color tone of the substrate 3 is too bright, which makes it difficult to distinguish between the glass fibers 4 that have not been wet out and the substrate 3 during image analysis described later, which is not preferable.

The material of the substrate 3 is not particularly limited as long as the value of the lightness L value is within the above range. For example, a resin plate such as an acrylic plate or a vinyl chloride plate, a metal plate whose surface is coated to suppress the metallic luster, and the like. Can be used, and an acrylic plate can be particularly preferably used. When an acrylic plate is used as the substrate 3, it is easy to adjust the color tone as described above, and the substrate 3 having various color tones can be used.

The resin impregnating property can be evaluated, for example, according to the block diagrams in the procedure of FIGS. 2A, 2B, 2C and 2D and the procedure of FIG.

That is, first, as shown in FIG. 2A, the glass fiber 4 to be evaluated is placed on the surface of the substrate 3, and the surfaces of the substrate 3 and the glass fiber 4 are covered with a colorless and transparent resin film 6, 1 is used to image the glass fiber 4 and the substrate 3.

By covering with the resin film 6, it is possible to suppress the scattering of the glass fiber 4 in a dry state, and after supplying the resin composition 5 described later, suppress the volatilization of the solvent component in the resin composition, and It is possible to ensure the impregnation of the resin composition 5 into the resin 4 and efficiently perform wet-out.

The material of the resin film 6 is not particularly limited as long as it is a colorless and transparent resin, and examples thereof include polyethylene terephthalate (PET) resin and vinyl chloride resin.

Next, in the above imaging step, the area S ₀ of the region corresponding to the glass fiber in the image obtained by imaging is calculated.

That is, the image data of the substrate 3 and the glass fiber 4 is input to the image processing device 2 such as a computer, and image analysis is performed. Since the image data is obtained by arranging the milky white glass fiber 4 having a high lightness L value on the upper surface of the substrate 3 having a low lightness L value, the image data of the lightness L value of the base 3 and the glass fiber 4 is obtained. Since the difference is large, the bright image portion showing the glass fiber 4 and the dark image portion showing the substrate 3 can be clearly distinguished. The bright image portion and the dark image portion of such image data are distinguished by the image processing device, and the area of the bright image portion is calculated by the image processing device as the area S ₀ of the region corresponding to the glass fiber 4. To do.

After that, as in the state of FIG. 1, the resin composition 5 or a part of the resin composition 5 (for example, a solvent or the like) was supplied to the glass fiber 4 to supply the resin composition 5 at the same position as the above step. The glass fiber 4 and the substrate 3 are imaged with time. 2(b), (c), and (d) schematically show the imaging over time. The notations (a), (b), (c), and (d) in FIG. 3 correspond to the above steps.

The main component of the resin composition 5 is not particularly limited as long as it is a resin normally used in the production of SMC and its molded products, and examples thereof include thermosetting unsaturated polyester resins, acrylic resins, epoxy resins, phenol resins and the like. Examples of the resin include a single type or a combination of two or more types. A solvent, a sizing agent and the like can be added to the resin composition 5 as long as the evaluation of the resin impregnation property of the glass fiber 4 is not hindered.

When the resin composition 5 is a resin composition that is highly colored or lacks transparency and is cloudy, even if the binder 44 of the glass fiber 4 is dissolved by the solvent component, the glass fiber is wet out. Does not become transparent, which makes it difficult to evaluate the resin impregnation property. In this case, a colorless and transparent resin composition containing a resin of the same type as the resin composition actually used for the production of SMC or its molded article as a main component may be used as the evaluation resin composition.

Further, it is preferably considered that the resin composition 5 supplied to the glass fiber 4 contains styrene as a solvent component. By impregnating the glass fiber 4 with the resin composition 5, styrene in the resin composition 5 can dissolve the binder 44 contained in the glass fiber 4. In the glass fiber 4, in the wet-out region where the binder 44 is melted by styrene, the refractive index values are close to those of the resin composition 5 and styrene, so that the glass fiber 4 changes to be substantially transparent. For example, the glass fiber generally used in the production of resin molded products is e-glass, its refractive index is 1.55, and the unsaturated polyester resin has a refractive index of about 1.54 to 1.57. The refractive index of styrene as a solvent component is 1.5339. Therefore, the color of the substrate 3 arranged below the glass fibers 4 can be visually recognized from the glass fibers 4.

Such a wet-out process of the glass fiber 4 is performed when the glass fiber 4 in the initial state shown in FIG. 2A is imaged, as shown in FIGS. 2B, 2C, and 2D. Images are taken with time using the camera 1 at the same position.

In the step of imaging with time, the lightness L value of the area corresponding to the substrate 3 in the image obtained by imaging is compared with that of the area corresponding to the glass fiber 4 after the resin composition 5 is supplied. Then, the area S ₁ of the wet-out region in which the difference in the brightness L value is 20 or less is calculated with time.

That is, the image data of the substrate 3 and the glass fiber 4 in which wet-out is progressing is input to the image processing device 2 such as a computer and image analysis is performed. As described above, by impregnating the glass fiber 4 with the resin composition 5, in the glass fiber 4, the glass fiber 4 becomes transparent in the wet-out region where the binder 44 is melted by styrene, and the color of the substrate 3 changes to the glass fiber 4. It can be confirmed from above. At this time, the lightness L value of the area corresponding to the substrate 3 is compared with the lightness L value of the area corresponding to the glass fiber 4 after the resin composition 5 is supplied, and the difference in the lightness L value is 30 or less than a predetermined value or less. If it is preferably 20 or less, it can be determined that wet-out has occurred in the glass fiber 4. The smaller the difference in the lightness L value between the region corresponding to the substrate 3 and the region corresponding to the glass fiber 4 after the resin composition 5 is supplied, the more it is considered that the wet-out is surely occurring. It is preferably considered that the difference between the lightness L values is 5 or more and 15 or less. The image processing device 2 compares the difference in the brightness L values and calculates the area S ₁ of the wet-out region.

Finally, the area ratio of the area S ₁ of the wet-out area to the area S ₀ of the area corresponding to the glass fiber 4 is calculated over time.

The area ratio (%) of the area S ₁ of the wet-out area to the area S ₀ of the area corresponding to the glass fiber 4 is calculated by the following calculation formula.

Then, the time when the area ratio of the area S ₁ of the wet-out area to the area S ₀ of the area corresponding to the glass fiber 4 becomes a predetermined value, preferably a predetermined value of 75% or more and 100% or less is obtained. Here, the threshold value of the area ratio can be arbitrarily set within a range of 75% or more and 100% or less. Particularly, as shown in FIG. 2D, it is exemplified that the wet-out is determined to be completed when the area ratio reaches 95%. On the other hand, when the impregnation of the resin composition into the glass fiber is less than 75%, the unimpregnated glass fiber remains inside the molded product, impairing the aesthetic appearance of the molded product and obtaining the desired strength. There is a risk that you will not be able to.

In the method for evaluating the resin impregnating property of the glass fiber for resin molded product of the present invention, the area ratio is a predetermined value for each of the plurality of types of glass fibers 4 having different binders 44 attached to the surface of the glass monofilament 42, It is also preferably considered to measure the time to reach 95% and compare the resin impregnating properties of a plurality of types of glass fibers.

Here, as the time until the area ratio reaches 95%, it is usually considered preferably to be within the range of the curing time in the manufacturing process of the molded product using SMC. The curing time is, for example, in the range of 5 minutes to 30 minutes. When the impregnation of the glass fiber with the resin composition is completed within the above range, a molded product having a desired strength can be obtained without lowering the productivity of the molded product. On the other hand, if the time required for the area ratio to reach 95% exceeds 30 minutes, the productivity of the molded product may decrease.

In this way, by comparing the times until the area ratio reaches 95%, for example, glass fibers having a high resin impregnation property and glass fibers having a low resin impregnation property can be evaluated and separated. Then, when manufacturing a resin molded product having a high demand for strength or a resin molded product having an extremely good appearance, it is possible to select the glass fiber optimal for each performance.

FIG. 3 shows a block diagram of a method for evaluating the resin impregnating property of glass fiber. In the process of evaluating the resin impregnating property of glass fiber, not only the above area ratio (%) calculation but also the area ratio is calculated. It also calculates the time to reach 95%.

Since the solubility of the binder 44 of the glass fiber 4 depends on the temperature, the above method for evaluating the resin impregnating property of the glass fiber for resin molded product is preferably carried out at a constant temperature. The temperature in this case is, for example, in the range of 15° C. or higher and 40° C. or lower, and it is preferably considered to be performed under room temperature conditions of about 25° C.

Examples will be shown below, but the method for evaluating the resin impregnating ability of the glass fiber for a resin molded article of the present invention is not limited to the examples.
(Example)
An unsaturated polyester resin (M540 manufactured by Showa Denko) was used as the resin composition. As the glass fiber, (A) SMC molding glass roving RS 480-550 (manufactured by Nitto Boseki) which is preferably used in a bathtub or the like, and (B) SMC molding glass roving RS 460 A-782 (which is used in an automobile body or the like). Nitto Boseki) was used.

One piece of the SMC molding glass roving cut into 1 inch was placed on a black acrylic plate having an L value of 42, which was a base, and the base and the glass fiber were covered with a transparent PET resin film. It was A camera was installed vertically above the glass fiber so that the entire substrate and glass fiber could be photographed, the base and glass fiber covered with the transparent PET resin film were imaged, and the obtained image data was image-processed to the initial stage. The area S ₀ of the region corresponding to the glass fiber in the state was calculated by the computer. Then, the PET film was once removed, unsaturated polyester resin diluted with styrene was supplied on the glass fiber, and the substrate and the glass fiber were quickly covered again with the PET resin film, and the image was taken as the start time at that time. After that, imaging was continued over time. Such time-lapse photographing was performed at the same position without moving the positions of the camera, the substrate and the glass fiber from the initial positions. Image processing was performed on the obtained image data, and the area S ₁ of the wet-out region in which the glass fiber was impregnated with the resin composition and the binder of the glass fiber was dissolved was calculated by a computer.

Percent ratio of the area S ₁ of the wet-out area to the area S ₀ of the region corresponding to the glass fiber in the initial state was calculated by the computer, the area S of the region area S ₁ of the wet-out area corresponds to the glass fibers in the initial state _The time when 95% of ₀ was reached was the wet-out completion time.

Table 1 shows the measurement results at room temperature of 23°C and liquid temperature of the resin composition of 23°C.

From the results of Table 1, in the SMC molding glass roving (A) that is preferably used for manufacturing a bathtub or the like, the area S ₁ of the wet-out region corresponds to the glass fiber in the initial state 15 minutes after the supply of the resin composition. It was confirmed that the area reached 95% of the area S ₀ and the wet-out was completed. On the other hand, in the SMC molding glass roving (B) that is preferably used for automobile bodies, etc., the area S ₁ of the wet-out area reaches 95% of the area S ₀ of the area corresponding to the glass fiber in the initial state, and It was confirmed that the time required for completion was 100 minutes after the supply of the resin composition.

From the above results, it can be seen that glass fibers having a high resin impregnation property and glass fibers having a low resin impregnation property can be separated.

1 Camera 2 Image Processing Device 3 Base 4 Glass Fiber 41 Glass Roving 42 Glass Strand 43 Glass Monofilament 44 Binder 5 Resin Composition 6 Resin Film S ₀ Area of Area Corresponding to Glass Fiber S ₁ Area of Wetout Area

Claims (4)

Used in a resin molded article molded resin composition, a glass fiber evaluation method of glass monofilament adhered by a binder,
Placing the glass fiber on a substrate having a lightness L value of 0 or more and 70 or less, and imaging the glass fiber and the substrate;
Calculating an area S _{0 of} a region corresponding to the glass fiber in the image obtained by the imaging in the imaging step;
Supplying the resin composition or a partial component thereof to the glass fiber, and a step of imaging with time the glass fiber supplied with the resin composition at the same position as the step,
In the image obtained in the step of imaging with time, the lightness L value is compared by comparing the lightness L value of the area corresponding to the substrate with the area corresponding to the glass fiber after the resin composition is supplied. Calculating the area S ₁ of the wet-out region in which the difference in value is smaller than a predetermined value of 30 or less over time,
Calculating the area ratio of the area S ₁ of the wet-out area to the area S ₀ of the area corresponding to the glass fiber over time,
Including and
For each of a plurality of types of glass fibers each having a different binder attached to the surface of the glass monofilament, the time until the area ratio reaches a predetermined value was measured, and the resin impregnability of the plurality of types of glass fibers was compared. Do
A method for evaluating resin impregnating ability of glass fiber for resin molded article, which is characterized in that. The said area ratio is 75% or more and 100% or less, The resin impregnation evaluation method of the glass fiber for resin moldings of Claim 1 characterized by the above-mentioned. The difference in lightness L value between the region corresponding to the substrate and the region corresponding to the glass fiber after the resin composition is supplied is 5 or more and 15 or less . Evaluation method of resin impregnating property of glass fiber for resin molded product. The resin composition according to claim 1, wherein the resin composition contains styrene as a solvent component .

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