Strength evaluation method of reinforced resin composite material

Abstract

To estimate strength of a reinforced resin composite material after moist heat treatment by a simple method without direct measurement.SOLUTION: A strength evaluation method of a reinforced resin composite material includes: a step S1 of calculating contribution strength B1' of a synthetic resin in a reinforced resin composite material after moist heat treatment, on the basis of strength A' of a synthetic resin simple substance after the moist heat treatment, and a mixing ratio V of a synthetic resin in a reinforced resin composite material; a step S2 of calculating contribution strength B2' of a glass composition in the reinforced resin composite material after the moist heat treatment, on the basis of contribution strength B2 of the glass composition in the reinforced resin composite material before the moist heat treatment, an adhesion rate r of the synthetic resin to the glass composition in the reinforced resin composite material before the moist heat treatment, and an adhesion rate r' of the synthetic resin to the glass composition in the reinforced resin composite material after the moist heat treatment; and a step S3 of estimating strength B' of the reinforced resin composite material after the moist heat treatment, on the basis of contribution strength B1' of the synthetic resin after the moist heat treatment, and contribution strength B2' of the glass composition after the moist heat treatment.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a method for evaluating the strength of a reinforced resin composite material. [Background technology]

[0002] Reinforced resin composites containing synthetic resins and glass compositions are widely used as materials for automobile structural parts, containers, etc. (see, for example, Patent Document 1).

[0003] Unlike metals, such reinforced resin composites do not rust, but they are subject to gradual deterioration due to hydrolysis caused by contact with water or moisture in the air, and their mechanical strength may decrease. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2023-074133 Summary of the Invention [Problem to be solved by the invention]

[0005] Incidentally, for the above-mentioned reinforced resin composite material, the mechanical strength may be measured after a wet heat treatment as an accelerated aging test in order to evaluate durability against degradation due to hydrolysis, etc. Examples of the measurement of mechanical strength include a tensile test for measuring tensile strength and a bending test for measuring bending strength.

[0006] However, when directly measuring the mechanical strength of a reinforced resin composite after the moist heat treatment, it is necessary to prepare a plurality of measurement samples that satisfy the dimensional conditions, etc., specified by the standard in advance, and then subject each measurement sample to the moist heat treatment and measure the mechanical strength by a tensile test, a bending test, etc. Therefore, when directly measuring the mechanical strength of a reinforced resin composite after the moist heat treatment, a very large number of steps are required. Furthermore, since the method for directly measuring the mechanical strength is basically a destructive test, if it is not possible to prepare a sufficient amount of glass composition, it may be difficult to directly measure the mechanical strength of a reinforced resin composite after the moist heat treatment.

[0007] An object of the present invention is to estimate the strength of a reinforced resin composite material after a heat-moisture treatment in a simple manner without directly measuring it. [Means for solving the problem]

[0008] (1) The present invention, which has been invented to solve the above-mentioned problems, is a strength evaluation method for estimating the strength of a reinforced resin composite containing a synthetic resin and a glass composition after moist heat treatment, and is characterized by comprising the steps of: calculating the contribution strength of the synthetic resin in the reinforced resin composite after moist heat treatment based on the strength of the synthetic resin alone after moist heat treatment and the mixing ratio of the synthetic resin in the reinforced resin composite; calculating the contribution strength of the glass composition in the reinforced resin composite after moist heat treatment based on the contribution strength of the glass composition in the reinforced resin composite before moist heat treatment, the adhesion rate of the synthetic resin to the glass composition in the reinforced resin composite before moist heat treatment, and the adhesion rate of the synthetic resin to the glass composition in the reinforced resin composite after moist heat treatment; and estimating the strength of the reinforced resin composite after moist heat treatment based on the contribution strength of the synthetic resin after moist heat treatment and the contribution strength of the glass composition after moist heat treatment.

[0009] As a result of extensive research, the present inventors have discovered that (a) the contribution strength of the synthetic resin after moist heat treatment is significantly affected by the mixing ratio of the synthetic resin in the reinforced resin composite, and (b) the contribution strength of the glass composition after moist heat treatment is significantly affected by the adhesion ratio (the rate of change in adhesion ratio) of the synthetic resin to the glass composition before and after the moist heat treatment. Specifically, they have discovered that (c) the contribution strength of the synthetic resin after moist heat treatment can be calculated based on the strength of the synthetic resin alone after moist heat treatment and the mixing ratio of the synthetic resin in the reinforced resin composite, and (d) the contribution strength of the glass composition after moist heat treatment can be calculated based on the contribution strength of the glass composition before moist heat treatment and the adhesion ratio of the synthetic resin to the glass composition before and after the moist heat treatment. Therefore, based on these findings, by calculating the contribution strength of the synthetic resin after moist heat treatment and the contribution strength of the glass composition after moist heat treatment, the strength of the reinforced resin composite after moist heat treatment can be estimated without directly measuring the strength of the reinforced resin composite after moist heat treatment.

[0010] (2) In the configuration of (1) above, it is preferable to further include the steps of: calculating the contribution strength of the synthetic resin in the reinforced resin composite before the moist heat treatment based on the strength of the synthetic resin alone before the moist heat treatment and the mixing ratio of the synthetic resin in the reinforced resin composite; and calculating the contribution strength of the glass composition before the moist heat treatment based on the strength of the reinforced resin composite before the moist heat treatment and the contribution strength of the synthetic resin before the moist heat treatment.

[0011] The contribution strength of the synthetic resin before the moist heat treatment, like the contribution strength of the synthetic resin after the moist heat treatment, is significantly affected by the mixing ratio of the synthetic resin in the reinforced resin composite. Therefore, the contribution strength of the synthetic resin before the moist heat treatment can be calculated based on the strength of the synthetic resin alone before the moist heat treatment and the mixing ratio of the synthetic resin in the reinforced resin composite. Furthermore, the contribution strength of the glass composition before the moist heat treatment can be calculated from the strength of the reinforced resin composite before the moist heat treatment and the contribution strength of the synthetic resin before the moist heat treatment, if these values ​​are known. Therefore, according to the above configuration, the contribution strength of the glass composition before the moist heat treatment can be easily calculated.

[0012] (3) In the above configuration (1) or (2), in the process of estimating the strength of the reinforced resin composite after the moist heat treatment, it is preferable to calculate the strength B' of the reinforced resin composite after the moist heat treatment using the following formula, where B1' [MPa] is the contribution strength of the synthetic resin after the moist heat treatment, B2' [MPa] is the contribution strength of the glass composition after the moist heat treatment, and α is the coefficient. B'=(B1'+B2')×α

[0013] The coefficient α is a coefficient for correcting the difference between the sum of the contribution strengths B1' and B2' and the strength B' of the reinforced resin composite material after the moist heat treatment. Therefore, with the above configuration, the strength of the reinforced resin composite material after the moist heat treatment can be accurately estimated.

[0014] (4) In any of the configurations (1) to (3) above, in the step of calculating the contribution strength of the synthetic resin after the moist heat treatment, it is preferable to calculate the contribution strength B1' [MPa] of the synthetic resin after the moist heat treatment using the following formula, where A' [MPa] is the strength of the synthetic resin alone after the moist heat treatment and V [%] is the mixing ratio of the synthetic resin in the reinforced resin composite. B1'=A'×(V / 100)

[0015] In this way, the contribution strength of the synthetic resin after the moist heat treatment can be calculated with high accuracy.

[0016] (5) In any of the above configurations (1) to (4), in the step of calculating the contributed strength of the glass composition after the moist heat treatment, it is preferable to calculate the contributed strength B2' [MPa] of the glass composition after the moist heat treatment by the following formula, where A [MPa] is the strength of the synthetic resin alone before the moist heat treatment, B [MPa] is the strength of the reinforced resin composite before the moist heat treatment, r [%] is the adhesion rate before the moist heat treatment, r' [%] is the adhesion rate after the moist heat treatment, and V [%] is the mixing rate of the synthetic resin in the reinforced resin composite. B2' = [B - {A × (V / 100)}] × (r' / r)

[0017] In this way, the contribution strength of the glass composition after the moist heat treatment can be calculated with high accuracy. In the formula, A×(V / 100) means the contribution strength of the synthetic resin before the moist heat treatment. In the formula, B-{A×(V / 100)} means the contribution strength of the glass composition before the moist heat treatment. In the formula, r' / r means the rate of change in the adhesion ratio before and after the moist heat treatment.

[0018] (6) In the configuration of (3) above, it is preferable to further include a step of calculating the coefficient α using a correction resin composite containing a correction glass composition and a correction synthetic resin, and in the step of calculating the coefficient α, it is preferable to measure the strength Bt' [MPa] of the correction resin composite after the moist heat treatment, and calculate the contribution strength Bt1' [MPa] of the correction synthetic resin and the contribution strength Bt2' [MPa] of the correction glass composition in the correction resin composite after the moist heat treatment, and to obtain the coefficient α using the following formula. α=Bt' / (Bt1'+Bt2')

[0019] In this way, the coefficient α can be calculated in advance with high accuracy, and therefore the strength of the reinforced resin composite material after the heat and humidity treatment can be estimated with high accuracy.

[0020] (7) In any of the above configurations (1) to (6), the adhesion rate is preferably determined by calculating the average ratio of the length of the adhesive portion between the glass composition and the synthetic resin to the contour length of the glass composition in a cross section including a plurality of glass compositions embedded in the synthetic resin.

[0021] In this way, the average value of the adhesion rates between the plurality of glass compositions and the synthetic resin is used as the adhesion rate for calculating the contributed strength of the glass composition after the moist heat treatment, and therefore, the adhesive states between the plurality of glass compositions and the synthetic resin are taken into consideration, so that the contributed strength of the glass composition after the moist heat treatment can be calculated more accurately.

[0022] (8) In any of the above configurations (1) to (7), the reinforced resin composite may contain, by mass %, 10 to 90% of a glass composition and 90 to 10% of a synthetic resin.

[0023] (9) In the above configuration (8), the glass composition is preferably glass fiber, and the glass composition preferably contains, by mass%, 50-80% SiO2, 30-30% Al2O, 30-30% B2O, 1-30% MgO+CaO+SrO+BaO, and 0-2% Li2O+Na2O+K2O. Note that "MgO+CaO+SrO+BaO" and "Li2O+Na2O+K2O" refer to the total amounts of the respective components.

[0024] (10) In the above configuration (8) or (9), the synthetic resin may include one or more resins selected from the group consisting of polyester resin, polyamide resin, polyolefin resin, styrene-based resin, polyacetal resin, polycarbonate resin, and polyphenylene sulfide resin.

[0025] (11) In any of the above (1) to (10), the step of estimating the strength of the reinforced resin composite material after the wet heat treatment may estimate the tensile strength measured in accordance with ASTM D638.

[0026] (12) In any of the above (1) to (10), the step of estimating the strength of the reinforced resin composite after the wet heat treatment may estimate the bending strength measured in accordance with ASTM D790.

[0027] (13) The present invention, which has been invented to solve the above-mentioned problems, is a strength evaluation method for estimating the strength of a reinforced resin composite containing a synthetic resin and a glass composition after moist heat treatment, characterized in that the strength of the reinforced resin composite after moist heat treatment is estimated based on the strength of the reinforced resin composite before moist heat treatment, the strength of the synthetic resin alone before moist heat treatment, the strength of the synthetic resin alone after moist heat treatment, the adhesion rate of the synthetic resin to the glass composition in the reinforced resin composite before moist heat treatment, and the adhesion rate of the synthetic resin to the glass composition in the reinforced resin composite after moist heat treatment.

[0028] In this way, the strength of the reinforced resin composite material after the moist heat treatment can be estimated without directly measuring the strength of the reinforced resin composite material after the moist heat treatment. [Effects of the Invention]

[0029] According to the present invention, the strength of a reinforced resin composite material after heat treatment can be estimated by a simple method without directly measuring it. [Brief explanation of the drawings]

[0030] [Figure 1] 1 is a flowchart showing a method for evaluating the strength of a reinforced resin composite material according to a first embodiment. [Figure 2] 1 is an example of an SEM image of a cross section of a reinforced resin composite material. [Figure 3] FIG. 3 is an enlarged view showing the periphery of one glass composition included in FIG. 2. [Figure 4] This is a binarized image obtained by processing the SEM image of FIG. 3 and displaying the glass composition separately from other components. [Figure 5] This is a binarized image obtained by processing the SEM image in Figure 3 and separating the peeled area from the rest. [Figure 6] 6 is an image of the overlapping portion when the glass composition of FIG. 4 and the peeled portion of FIG. 5 are overlapped after being subjected to expansion treatment. [Figure 7] 7 is an image showing the skeleton lines of the overlapping portion in FIG. 6. [Figure 8] 10 is a flowchart showing a method for evaluating the strength of a reinforced resin composite material according to a second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0031] Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings.

[0032] First Embodiment The method for evaluating the strength of a reinforced resin composite material according to the first embodiment is a method for estimating the strength of a reinforced resin composite material containing a synthetic resin and a glass composition after a moist heat treatment.

[0033] The reinforced resin composite material contains, for example, in mass %, 10 to 90% of a glass composition and 90 to 10% of a synthetic resin.

[0034] Examples of glass compositions include glass fibers. Examples of the shape of the glass fibers include chopped fibers having a longitudinal length (fiber length) of 1 to 50 mm and a transverse length (fiber width) of 3 to 40 μm, and milled fibers having a longitudinal length (fiber length) of 10 μm to 1 mm and a transverse length (fiber width) of 3 to 40 μm. The aspect ratio of the glass fibers (longitudinal length / transverse length) is preferably 25 to 1667 for chopped fibers and 0.25 to 333 for milled fibers.

[0035] The glass composition contains, for example, in mass %, 50 to 80% of SiO2, 30 to 30% of Al2O, 30 to 30% of B2O, 1 to 30% of MgO+CaO+SrO+BaO, and 0 to 2% of Li2O+Na2O+K2O.

[0036] The synthetic resin includes, for example, one or more resins selected from the group consisting of the following (a) to (g): These are usually used alone, but two or more types can be used in combination depending on the application. (a) Polyester resins such as polyethylene terephthalate (PET) resin and polybutylene terephthalate (PBT) resin (b) Polyamide resins such as 6-nylon resin and 6,6-nylon (c) Polyolefin resins such as polyethylene resins and polypropylene resins, (d) styrene resins such as AS resin and ABS resin; (e) polyacetal resin, (f) polycarbonate resin, (g) Polyphenylene sulfide resin

[0037] Reinforced resin composites can be formed, for example, by injection molding.

[0038] The conditions for the wet heat treatment of the reinforced resin composite material are, for example, in an autoclave at a temperature of 100 to 135°C, a humidity of 100%, and a treatment time of 1 to 300 hours.

[0039] As shown in Figure 1, the strength evaluation method for reinforced resin composites according to this embodiment includes step S1 of calculating the contribution strength B1' [MPa] of the synthetic resin in the reinforced resin composite after the moist heat treatment, step S2 of calculating the contribution strength B2' [MPa] of the glass composition in the reinforced resin composite after the moist heat treatment, and step S3 of estimating the strength B' [MPa] of the reinforced resin composite after the moist heat treatment.

[0040] Here, the contribution strength B1' of the synthetic resin in the reinforced resin composite after the moist heat treatment (hereinafter simply referred to as the "contribution strength of the synthetic resin after the moist heat treatment") refers to the strength of the reinforced resin composite after the moist heat treatment contributed by the synthetic resin contained in the reinforced resin composite (the strength increased by the synthetic resin). The contribution strength B2' of the glass composition in the reinforced resin composite after the moist heat treatment (hereinafter simply referred to as the "contribution strength of the glass composition after the moist heat treatment") refers to the strength of the reinforced resin composite after the moist heat treatment contributed by the glass composition contained in the reinforced resin composite (the strength increased by the glass composition). Similarly, the contribution strength B1 of the synthetic resin in the reinforced resin composite before the moist heat treatment (hereinafter simply referred to as the "contribution strength of the synthetic resin before the moist heat treatment"), which will be described later, refers to the strength of the reinforced resin composite before the moist heat treatment contributed by the synthetic resin contained in the reinforced resin composite. The contribution strength B2 of the glass composition in the reinforced resin composite before the moist heat treatment (hereinafter also referred to simply as the "contribution strength of the glass composition before the moist heat treatment"), which will be described later, means the strength of the reinforced resin composite before the moist heat treatment that is contributed by the glass composition contained in the reinforced resin composite.

[0041] In step S1, the contribution strength B1' [MPa] of the synthetic resin after the moist heat treatment is calculated based on the strength A' [MPa] of the synthetic resin alone after the moist heat treatment and the mixing ratio V [%] of the synthetic resin in the reinforced resin composite.

[0042] Specifically, in this embodiment, the contribution strength B1' [MPa] of the synthetic resin after the wet heat treatment is calculated by the following formula. (Formula 1) B1'=A'×(V / 100)

[0043] If the strength A' [MPa] of the synthetic resin alone after the moist heat treatment is not known, the method may further include a step of determining the strength A' [MPa] of the synthetic resin alone after the moist heat treatment before step S1.

[0044] The process of determining the strength A' [MPa] of the synthetic resin alone after moist heat treatment includes the steps of preparing a resin sample made of the same material as the synthetic resin contained in the reinforced resin composite, subjecting the resin sample to moist heat treatment under substantially the same conditions as for the reinforced resin composite, and measuring the strength A' [MPa] of the resin sample alone after moist heat treatment.

[0045] In step S3, when estimating the tensile strength measured in accordance with ASTM D638, the strength A' [MPa] of the resin sample alone after the moist heat treatment is measured as the tensile strength measured in accordance with the same standard. Similarly, in step S3, when estimating the flexural strength measured in accordance with ASTM D790, the strength A' [MPa] of the resin sample alone after the moist heat treatment is measured as the flexural strength measured in accordance with the same standard.

[0046] In step S2, the contribution strength B2' [MPa] of the glass composition in the reinforced resin composite after the moist heat treatment is calculated based on the contribution strength B2 [MPa] of the glass composition in the reinforced resin composite before the moist heat treatment, the adhesion rate r of the synthetic resin to the glass composition before the moist heat treatment, and the adhesion rate r' [%] of the synthetic resin to the glass composition after the moist heat treatment.

[0047] Specifically, in this embodiment, the contribution strength B2' [MPa] of the glass composition after the moist heat treatment is calculated by the following formula. (Formula 2) B2'=B2×(r' / r)

[0048] Furthermore, the contribution strength B2 [MPa] of the glass composition before the moist heat treatment is calculated by the following formula, where the strength of the reinforced resin composite before the moist heat treatment is B [MPa] and the contribution strength of the glass composition before the moist heat treatment is B1 [MPa]. (Formula 3) B2=B-B1

[0049] The contribution strength B1 [MPa] of the glass composition before the moist heat treatment is calculated by the following formula, where the strength of the synthetic resin alone before the moist heat treatment is A [MPa] and the volume mixing ratio of the synthetic resin in the reinforced resin composite is V [%]. (Formula 4) B1=A×(V / 100)

[0050] That is, the contribution strength B2 [MPa] of the glass composition before the moist heat treatment can be expressed as the following formula by modifying formula 3 using formula 4. (Formula 5) B2=B-{A×(V / 100)}

[0051] Therefore, the contribution strength B2′ [MPa] of the glass composition after the heat-and-moisture treatment can be expressed as follows by modifying Equation 2 using Equation 5: (Formula 6) B2' = [B - {A × (V / 100)}] × (r' / r)

[0052] When calculating the contributed strength B2' of the glass composition after the moist heat treatment from Equation 6, if the strength A [MPa] of the synthetic resin alone before the moist heat treatment is not known, the method may further include a step of determining the strength A [MPa] of the synthetic resin alone before the moist heat treatment before step S2.

[0053] The step of determining the strength A [MPa] of the synthetic resin alone before moist heat treatment includes the steps of preparing a resin sample made of the same material as the synthetic resin contained in the reinforced resin composite and measuring the strength A of the resin sample alone before moist heat treatment. When estimating the tensile strength measured in accordance with ASTM D638 in step S3, the strength A of the resin sample alone before moist heat treatment is measured in accordance with the same standard. Similarly, when estimating the flexural strength measured in accordance with ASTM D790 in step S3, the strength A of the resin sample alone before moist heat treatment is measured in accordance with the same standard.

[0054] When calculating the contribution strength B2' of the glass composition after the moist heat treatment from Equation 6, if the strength B [MPa] of the reinforced resin composite before the moist heat treatment is not known, the method may further include a step of determining the strength B [MPa] of the reinforced resin composite before the moist heat treatment before step S2.

[0055] The step of determining the strength B [MPa] of the reinforced resin composite before moist heat treatment includes the steps of preparing a composite sample made of the same material as the reinforced resin composite and measuring the strength B of the composite sample before moist heat treatment. In step S3, when estimating the tensile strength measured in accordance with ASTM D638, the tensile strength measured in accordance with the same standard is used as the strength B of the composite sample before moist heat treatment. Similarly, in step S3, when estimating the flexural strength measured in accordance with ASTM D790, the flexural strength measured in accordance with the same standard is used as the strength B of the composite sample before moist heat treatment.

[0056] When calculating the contribution strength B2' of the glass composition after the moist heat treatment from Equation 6, if the adhesion ratio r [%] before the moist heat treatment is not known, the method may further include a step of determining the adhesion ratio r [%] before the moist heat treatment before step S2. Similarly, if the adhesion ratio r' [%] after the moist heat treatment is not known, the method may further include a step of determining the adhesion ratio r' [%] after the moist heat treatment before step S2. Note that the step of determining the adhesion ratio r [%] before the moist heat treatment is substantially the same as the step of determining the adhesion ratio r' [%] after the moist heat treatment, except for whether or not the moist heat treatment is performed. Therefore, the step of determining the adhesion ratio r [%] before the moist heat treatment will be described below as an example.

[0057] The process of determining the adhesion rate r [%] before the moist heat treatment includes the steps of preparing an adhesion rate measurement sample made of the same material as the reinforced resin composite, and measuring the adhesion rate of the synthetic resin to the glass composition in the adhesion rate measurement sample.

[0058] In the step of preparing a sample for measuring the adhesion rate, the reinforced resin composite is cut to a predetermined size (for example, about 10 mm square) to prepare a sample for measuring the adhesion rate (cut sample). In this case, using water may cause hydrolysis, so it is preferable to use dry cutting with a saw or the like.

[0059] Next, the cross section of the adhesion test sample is polished with abrasive paper. Specifically, the cross section of the adhesion test sample is smoothed by gradually changing from abrasive paper with a smaller grit size to abrasive paper with a larger grit size. In this case, dry polishing is preferably used because the use of water may accelerate hydrolysis.

[0060] The polished cross section of the adhesion test sample is then ultra-smoothed by irradiating it with an ion beam such as a broad ion beam (BIB), focused ion beam (FIB), or plasma-focused ion beam (PFIB).

[0061] The step of calculating the adhesion rate includes a step of observing the ultra-smoothed cross section of the adhesion rate measurement sample, and a step of analyzing the observation results to calculate the adhesion rate.

[0062] The method for observing the cross section of the adhesion rate measurement sample is preferably a method that allows observation of the state of the interface between the glass composition and the synthetic resin, and in this embodiment, a scanning electron microscope (SEM) is used.

[0063] In order to prevent peeling at the interface between the glass composition and the synthetic resin due to electron beam damage during SEM observation, the acceleration voltage of the electron beam is preferably 10 kV or less, more preferably 7 kV or less, and even more preferably 3 kV or less.

[0064] Furthermore, by lowering the accelerating voltage of the electron beam in this manner, the range of internal scattering of electrons incident from the sample surface can be narrowed, making the interface between the glass composition and the synthetic resin clearer and enabling a more accurate evaluation of the adhesion rate.

[0065] In order to prevent peeling at the interface between the glass composition and the synthetic resin due to electron beam damage during SEM observation, or to suppress charging due to electron beam irradiation, it is preferable to form a conductive vapor-deposited film on the cross section of the adhesion rate measurement sample. Examples of the vapor-deposited film include a platinum (Pt) film and an osmium (Os) film. The thickness of the vapor-deposited film is preferably 10 nm or less, more preferably 5 nm or less, even more preferably 3 nm or less, and particularly preferably 1 nm or less.

[0066] The interface between the glass composition and the synthetic resin is preferably observed using a backscattered electron image (BSE) of an SEM. When the cross section of the adhesion test sample is processed using an ion beam, minute irregularities may be formed due to slight differences in the ion beam cutting ability of each component that makes up the adhesion test sample. However, observation using a backscattered electron image can suppress the contrast caused by minute irregularities on the cross section of the adhesion test sample, allowing for more accurate evaluation of the adhesion rate.

[0067] In the backscattered electron image, contrast is generated by the average atomic number of each component that makes up the adhesion rate measurement sample. Specifically, the glass composition is the brightest, the synthetic resin is the next brightest, and the peeled portion at the interface between the glass composition and the synthetic resin is the darkest. This brightness difference is used to quantitatively evaluate the adhesion rate.

[0068] From the observation results, the average value of the ratio of the length of the bonded portion between the glass composition and the synthetic resin to the contour length of the glass composition is calculated for a plurality of glass compositions, and this average value is taken as the adhesion ratio.

[0069] The adhesion rate is expressed as the ratio of the length of the bonded portion between the glass composition and the synthetic resin to the contour length of the glass composition. In other words, if the synthetic resin is bonded along the entire contour of the glass composition, the adhesion rate is 100%. On the other hand, if the synthetic resin is peeled off along the entire contour of the glass composition, the adhesion rate is 0%. The adhesion rates were calculated using the same procedure for 100 glass compositions included in the adhesion rate measurement sample, and the average value was taken as the adhesion rate r of the adhesion rate measurement sample.

[0070] 2 and 3, the adhesion ratio is calculated using an SEM image taken at a magnification that allows confirmation of a peeled portion 3 at the interface between a glass composition 1 and a synthetic resin 2. The obtained SEM image is analyzed using Image J, an image analysis software, to determine the adhesion ratio.

[0071] Specifically, as shown in FIG. 4, the glass composition 1 and the others are displayed separately from the contrast of the SEM image by image processing (binarization), and the contour length L1 of the glass composition 1 is determined.

[0072] Similarly, as shown in FIG. 5, based on the contrast of the SEM image, the peeled portion 3 at the interface between the glass composition and the synthetic resin and the other portions are displayed separately by image processing (binarization).

[0073] Next, using "Dilate" in Image J, an SEM image of the expanded glass composition 1 shown separately in Figure 4 and an SEM image of the expanded peeled portion 3 shown separately in Figure 5 are created. The two expanded SEM images are then superimposed, and the overlapping portion 4 between the glass composition 1 and the peeled portion 3 is extracted as shown in Figure 6. Thereafter, as shown in Figure 7, a skeleton line 5 of the overlapping portion 4 is extracted, and the skeleton line length L2 is determined. The adhesion rate r [%] is then calculated using the calculated outline length L1 and skeleton line length L2 of the glass composition using the following formula. (Formula 7) r={(L1-L2) / L1}×100

[0074] Using the same procedure, the adhesion rates are determined for each of a plurality of glass compositions (e.g., 100 pieces) included in the adhesion rate measurement sample, and the average value is used as the adhesion rate r in Equation 6. For the adhesion rate r' after moist heat treatment, using the same procedure, the adhesion rates are determined for each of a plurality of glass compositions (e.g., 100 pieces) included in the adhesion rate measurement sample after moist heat treatment, and the average value is used as the adhesion rate r' in Equation 6.

[0075] In step S3, the strength B' [MPa] of the reinforced resin composite after the moist heat treatment is calculated based on the contribution strength B1' [MPa] of the synthetic resin after the moist heat treatment calculated in step S1 and the contribution strength B2' [MPa] of the glass composition after the moist heat treatment calculated in step S2.

[0076] Specifically, the strength B' of the reinforced resin composite material after the wet heat treatment is calculated by the following formula. (Formula 8) B'=B1'+B2'

[0077] That is, the strength B' of the reinforced resin composite material after the heat and humidity treatment can be expressed as follows by modifying Equation 8 using Equations 1 and 6: (Formula 9) B'={V×(A'×rA×r')+100×B×r'} / (100×r)

[0078] In this way, the strength of the reinforced resin composite after the heat treatment can be estimated in a simple manner without directly measuring it. Note that, since Equation 9 includes information on the contribution strength B1' [MPa] of the synthetic resin after the moist heat treatment and information on the contribution strength B2' [MPa] of the glass composition after the moist heat treatment, calculating the strength B' of the reinforced resin composite after the moist heat treatment from Equation 9 can be equivalent to simultaneously performing steps S1 to S3.

[0079] Second Embodiment The difference between the second embodiment of the strength evaluation method for reinforced resin composites and the first embodiment is that in step S3 of estimating the strength B' [MPa] of the reinforced resin composite after moist heat treatment, the strength B' of the reinforced resin composite after moist heat treatment is calculated using the following formula. (Formula 10) B'=(B1'+B2')×α

[0080] That is, Equation 10 can be rewritten as follows: (Formula 11) B'=[{V×(A'×rA×r')+100×B×r'} / (100×r)]×α

[0081] Here, α in the formula is a coefficient used to correct the difference between the sum of the contribution strengths B1' and B2' and the strength B' of the reinforced resin composite after the moist heat treatment. Therefore, by using formula 11, the strength of the reinforced resin composite after the moist heat treatment can be accurately estimated.

[0082] As shown in FIG. 8, the strength evaluation method for a reinforced resin composite according to this embodiment further includes, before steps S1 to S3, step S4 of calculating a coefficient α using a correction resin composite.

[0083] The correction resin composite includes a correction synthetic resin and a correction glass composition. The correction synthetic resin is the same material as the synthetic resin contained in the reinforced resin composite (the object for calculating the strength B'). On the other hand, the correction glass composition is a different material from the glass composition contained in the reinforced resin composite. However, since the coefficient α is easily affected by the shape (aspect ratio) of the glass composition, it is preferable that the shape of the correction glass composition is substantially the same as the shape of the glass composition contained in the reinforced resin composite.

[0084] Process S4 for calculating coefficient α includes the steps of preparing a correction resin composite, measuring the strength Bt' [MPa] of the correction resin composite after the moist heat treatment, calculating the contribution strength Bt1' [MPa] of the correction synthetic resin in the correction resin composite after the moist heat treatment, and calculating the contribution strength Bt2' [MPa] of the correction glass composition in the correction resin composite after the moist heat treatment.

[0085] In the step of measuring the strength Bt' [MPa] of the compensation resin composite after the moist heat treatment, the strength Bt' [MPa] of the compensation resin composite after the moist heat treatment is actually measured by a destructive test or the like. Specifically, when estimating the tensile strength measured in accordance with ASTM D638 as the strength B' of the reinforced resin composite after the moist heat treatment, it is preferable to measure the tensile strength in accordance with the same standard as the strength Bt' of the compensation resin composite after the moist heat treatment. Similarly, when estimating the flexural strength measured in accordance with ASTM D790 as the strength B' of the reinforced resin composite after the moist heat treatment, it is preferable to measure the flexural strength in accordance with the same standard as the strength Bt' of the compensation resin composite after the moist heat treatment.

[0086] The contribution strength B1t' of the compensation synthetic resin after the moist heat treatment and the contribution strength Bt2' of the compensation glass composition after the moist heat treatment can be calculated by substantially the same method as the contribution strength B1' of the synthetic resin after the moist heat treatment and the contribution strength B2' of the glass composition after the moist heat treatment already described. Note that the moist heat treatment is carried out under substantially the same conditions as those for the reinforced resin composite (the object for which strength B' is to be determined).

[0087] In detail, in the process of calculating the contribution strength B1t' [MPa] of the correction synthetic resin after the moist heat treatment, if the strength of the correction synthetic resin alone after the moist heat treatment is At' [MPa] and the volume mixing ratio of the correction synthetic resin in the correction resin composite is Vt [%], the contribution strength B1t' [MPa] of the correction synthetic resin after the moist heat treatment is calculated using the following formula. (Formula 12) B1t' = At' × (Vt / 100)

[0088] When estimating the strength B' of the reinforced resin composite after moist heat treatment based on the tensile strength measured in accordance with ASTM D638, it is preferable to measure the strength At' of the compensation synthetic resin alone after moist heat treatment based on the same standard. Similarly, when estimating the bending strength measured in accordance with ASTM D790 as the strength B' of the reinforced resin composite after moist heat treatment, it is preferable to measure the bending strength At' of the compensation synthetic resin alone after moist heat treatment based on the same standard. In other words, the strength Bt' of the compensation resin composite after moist heat treatment and the strength At' of the compensation synthetic resin alone after moist heat treatment may be measured in accordance with a different standard from the strength B' of the reinforced resin composite after moist heat treatment to be estimated. However, the strengths Bt' and At' are measured in accordance with the same standard. It is also preferable that the strengths B', Bt', and At' all comply with the same standard. Since the compensation synthetic resin is the same material as the synthetic resin contained in the reinforced resin composite, the strength At' of the compensation synthetic resin alone after the moist heat treatment can also be used as the strength A' of the synthetic resin alone after the moist heat treatment. In other words, if the strength At' of the compensation synthetic resin alone after the moist heat treatment is measured, it is not necessary to measure the strength A' of the synthetic resin alone after the moist heat treatment.

[0089] In the process of calculating the contribution strength Bt2' [MPa] of the correction glass composition after moist heat treatment, the strength of the correction resin composite before moist heat treatment is Bt [MPa], the strength of the correction synthetic resin alone before moist heat treatment is At [MPa], the mixing ratio of the correction synthetic resin in the correction resin composite is Vt [%], the adhesion rate of the correction synthetic resin to the correction glass composition before moist heat treatment is rt [%], and the adhesion rate of the correction synthetic resin to the correction glass composition after moist heat treatment is rt' [%].The contribution strength B2t' [MPa] of the correction glass composition after moist heat treatment is calculated using the following formula. (Formula 13) B2t'=[Bt-{At×(Vt / 100)}]×(rt' / rt)

[0090] In addition, since the compensation synthetic resin is the same material as the synthetic resin contained in the reinforced resin composite, the strength At of the compensation synthetic resin alone before the moist heat treatment is the same as the strength A of the synthetic resin alone before the moist heat treatment. Therefore, the value of the strength At can be substituted for the value of the strength A. In other words, if the strength At of the compensation synthetic resin alone before the moist heat treatment is measured, it is not necessary to measure the strength A of the synthetic resin alone before the moist heat treatment.

[0091] Then, in the process of calculating the coefficient α, the coefficient α is calculated using the strength Bt' (actual measured value) [MPa] of the correction resin composite after the moist heat treatment, the contribution strength B1t' [MPa] of the correction synthetic resin after the moist heat treatment, and the contribution strength B2t' [MPa] of the correction glass composition after the moist heat treatment, according to the following formula. (Formula 14) α=Bt' / (Bt1'+Bt2')

[0092] That is, the coefficient α can be expressed as follows by transforming Equation 14 using Equations 12 and 13: (Formula 15) α=(100×Bt'×rt) / {Vt×(At'×rt-At×rt')+100×Bt×rt'}

[0093] In this way, the coefficient α can be calculated in advance with high accuracy, and therefore, the strength of the reinforced resin composite material after the heat-and-moisture treatment can be estimated with high accuracy using Equation 11.

[0094] The present invention is not limited to the configuration of the above-described embodiment, nor is it limited to the above-described effects. The present invention can be modified in various ways without departing from the spirit of the present invention.

[0095] In the above embodiment, the volumetric mixing ratio of the synthetic resin and the compensation synthetic resin is used to calculate the contribution strength B1' of the synthetic resin after the moist heat treatment and the contribution strength B1t' of the compensation synthetic resin after the moist heat treatment. However, the contribution strengths B1' and B1t' may be calculated using a mixing ratio other than the volumetric mixing ratio, such as a weight mixing ratio. Furthermore, if the contents of the glass composition (glass fiber) and resin are known in advance, it is preferable to calculate the mixing ratio of the synthetic resin and the compensation synthetic resin based on the contents. On the other hand, the mixing ratio of the synthetic resin and the compensation synthetic resin may be estimated based on cross-sectional images or analysis results of the target sample. Examples of methods for obtaining cross-sectional images and analysis results include methods using devices such as SEM and X-ray CT.

[0096] In the second embodiment, for example, α may be set to a predetermined constant (for example, α = 1), and the step of calculating α may be omitted. However, in order to accurately estimate the strength of the reinforced resin composite material after the moist heat treatment, it is preferable to perform the step of calculating α in advance. In particular, when the shape of the glass fiber is chopped, α tends to deviate significantly from 1, so it is preferable to perform the step of calculating α in advance.

[0097] The present invention further includes the following inventions.

[0098] (1) A strength evaluation method for estimating a strength of a first reinforced resin composite material containing a first synthetic resin and a first glass composition after a moist heat treatment, the method comprising: An estimation formula derivation step (step S4) of deriving an estimation formula to be used for the estimation based on predetermined characteristics before and after the moist heat treatment of a second reinforced resin composite (correction resin composite) including a second synthetic resin (correction synthetic resin) and a second glass composition (correction glass composition) and predetermined characteristics of the second synthetic resin before and after the moist heat treatment; A step of determining predetermined properties of the first reinforced resin composite before and after the wet heat treatment (steps S1 to S2); and a step (step S3) of estimating the strength of the first reinforced resin composite material based on the estimation formula and the characteristics of the first reinforced resin composite material.

[0099] (2) In the above configuration (1), it is preferable that the second synthetic resin is made of the same material as the first synthetic resin, and the second glass composition is made of a different material from the first glass composition. [Example]

[0100] The present invention will be described in detail below based on examples, but the present invention is not limited to these examples.

[0101] In Examples Nos. 1 to 3 of the present invention, after performing step S4 of calculating the coefficient α using a correction resin composite, steps S1 to S3 are performed to estimate the strength of the reinforced resin composite using the calculated coefficient α.

[0102] Step S4 of calculating the coefficient α is performed under the conditions shown in Table 1. Specifically, a compensation synthetic resin and a compensation resin composite were prepared. Then, using the prepared compensation synthetic resin and compensation resin composite, the measured strength Bt of the compensation resin composite before moist heat treatment, the measured strength Bt' of the compensation resin composite after moist heat treatment, the measured strength At of the compensation synthetic resin alone before moist heat treatment, the measured strength At' of the compensation synthetic resin alone after moist heat treatment, the adhesion ratio rt before moist heat treatment, and the adhesion ratio rt' after moist heat treatment were measured. These values ​​were then used to calculate the coefficient α from Equation 15.

[0103] In Examples 1 to 3, the compensation resin composite material contains a synthetic resin made of polybutylene terephthalate (PBT) and a glass composition (glass fiber) having a glass composition X shown in Table 2. In the table, "tensile test" is a tensile test conducted in accordance with ASTM D638, and "bending test" is a bending test conducted in accordance with ASTM D790.

[0104] [Table 1]

[0105] [Table 2]

[0106] Steps S1 to S3 for estimating the strength of the reinforced resin composite are performed under the conditions shown in Table 3 using the obtained coefficient α. Specifically, a synthetic resin and a reinforced resin composite are prepared. Using the prepared synthetic resin and reinforced resin composite, the measured strength B of the reinforced resin composite before moist heat treatment, the measured strength A of the synthetic resin alone before moist heat treatment, the measured strength A' of the synthetic resin alone after moist heat treatment, the adhesion ratio r (average value for 100 glass compositions) before moist heat treatment, and the adhesion ratio r' (average value for 100 glass compositions) after moist heat treatment are measured. These values ​​and the coefficient α are then used to calculate the estimated strength B' of the reinforced resin composite after moist heat treatment using Equation 11. Separately, the measured strength B' of the reinforced resin composite after moist heat treatment was measured, and the measured strength B was compared with the estimated strength B' calculated using Equation 11.

[0107] In Examples 1 to 3, the reinforced resin composite material contains a synthetic resin made of polybutylene terephthalate (PBT) and a glass composition (glass fiber) having a glass composition Y shown in Table 4. In the table, "tensile test" refers to a tensile test conducted in accordance with ASTM D638, and "bending test" refers to a bending test conducted in accordance with ASTM D790. Since the coefficient α varies depending on the aspect ratio of the glass composition and the method of measuring mechanical strength, the aspect ratio of the glass composition and the method of measuring mechanical strength are substantially the same for the corrective resin composite material and the reinforced resin composite material (the object of strength estimation).

[0108] [Table 3]

[0109] [Table 4]

[0110] Table 3 also shows that the estimated strength B' [MPa] of the reinforced resin composite after moist heat treatment using Equation 11 is very close to the actually measured strength B' [MPa] of the reinforced resin composite after moist heat treatment, demonstrating high estimation accuracy. [Explanation of symbols]

[0111] 1. Glass composition 2. Synthetic resin 3 Peeling part 4 Overlapped section 5 Skeleton line

Claims

1. A strength evaluation method for estimating the strength of a reinforced resin composite material containing a synthetic resin and a glass composition after a moist heat treatment, comprising: Calculating the contribution strength of the synthetic resin in the reinforced resin composite after the moist heat treatment based on the strength of the synthetic resin alone after the moist heat treatment and the mixing ratio of the synthetic resin in the reinforced resin composite; calculating a contribution strength of the glass composition in the reinforced resin composite after the moist heat treatment based on a contribution strength of the glass composition in the reinforced resin composite before the moist heat treatment, an adhesion rate of the synthetic resin to the glass composition in the reinforced resin composite before the moist heat treatment, and an adhesion rate of the synthetic resin to the glass composition in the reinforced resin composite after the moist heat treatment; and estimating the strength of the reinforced resin composite material after the moist heat treatment based on the contribution strength of the synthetic resin after the moist heat treatment and the contribution strength of the glass composition after the moist heat treatment.

2. Calculating the contribution strength of the synthetic resin in the reinforced resin composite before the moist heat treatment based on the strength of the synthetic resin alone before the moist heat treatment and the mixing ratio of the synthetic resin in the reinforced resin composite; 2. The strength evaluation method for a reinforced resin composite according to claim 1, further comprising a step of calculating a contribution strength of the glass composition before the moist heat treatment based on a strength of the reinforced resin composite before the moist heat treatment and a contribution strength of the synthetic resin before the moist heat treatment.

3. In the step of estimating the strength of the reinforced resin composite material after the moist heat treatment, The contribution strength of the synthetic resin after the wet heat treatment is B1' [MPa], The contribution strength of the glass composition after the moist heat treatment is B2′ [MPa], When the coefficient is α, 3. The strength evaluation method for a reinforced resin composite material according to claim 1, wherein a strength B' of the reinforced resin composite material after the wet heat treatment is calculated by the following formula: B'=(B1'+B2')×α

4. In the step of calculating the contribution strength of the synthetic resin after the moist heat treatment, The strength of the synthetic resin alone after the wet heat treatment is A' [MPa], When the mixing ratio of the synthetic resin in the reinforced resin composite material is V [%], 4. The strength evaluation method for a reinforced resin composite material according to claim 3, wherein the contribution strength B1′ [MPa] of the synthetic resin after the wet heat treatment is calculated by the following formula: B1'=A'×(V / 100)

5. In the step of calculating the contributed strength of the glass composition after the moist heat treatment, The strength of the synthetic resin alone before the wet heat treatment is A [MPa], The strength of the reinforced resin composite material before the wet heat treatment is B [MPa], The adhesion rate before the moist heat treatment is r [%], The adhesion rate after the moist heat treatment is r' [%], When the mixing ratio of the synthetic resin in the reinforced resin composite material is V [%], 5. The strength evaluation method for a reinforced resin composite material according to claim 3, wherein the contributed strength B2′ [MPa] of the glass composition after the moist heat treatment is calculated by the following formula: B2'=[B-{A×(V / 100)}]×(r' / r)

6. The method further includes a step of calculating the coefficient α using a correction resin composite material containing a correction glass composition and a correction synthetic resin, In the step of calculating the coefficient α, The strength Bt' [MPa] of the compensation resin composite material after the wet heat treatment is measured, and Calculate the contribution strength Bt1′ [MPa] of the compensation synthetic resin and the contribution strength Bt2′ [MPa] of the compensation glass composition in the compensation resin composite material after the moist heat treatment, 4. The strength evaluation method for a reinforced resin composite material according to claim 3, wherein the coefficient α is calculated by the following formula: α=Bt' / (Bt1'+Bt2')

7. 3. The strength evaluation method for a reinforced resin composite material according to claim 1, wherein the adhesion rate is determined by calculating an average value of a ratio of a length of an adhesive portion between the glass composition and the synthetic resin to a contour length of the glass composition in a cross section including a plurality of glass compositions embedded in the synthetic resin.

8. 3. The method for evaluating the strength of a reinforced resin composite material according to claim 1, wherein the reinforced resin composite material contains, in mass %, 10 to 90% of a glass composition and 90 to 10% of a synthetic resin.

9. The glass composition is a glass fiber, and the glass composition contains, in mass %, SiO ２ 50-80%, Al ２ O ３ 0-30%, B ２ O ３ 0-30%, MgO+CaO+SrO+BaO 1-30%, Li ２ O + Na ２ O+K ２ The strength evaluation method for a reinforced resin composite material according to claim 8, wherein the reinforced resin composite material contains 0 to 2% of O.

10. 9. The strength evaluation method for a reinforced resin composite material according to claim 8, wherein the synthetic resin comprises one or more resins selected from the group consisting of polyester resin, polyamide resin, polyolefin resin, styrene-based resin, polyacetal resin, polycarbonate resin, and polyphenylene sulfide resin.

11. 3. The strength evaluation method for a reinforced resin composite according to claim 1, wherein the step of estimating the strength of the reinforced resin composite after the wet heat treatment includes estimating a tensile strength measured in accordance with ASTM D638.

12. 3. The strength evaluation method for a reinforced resin composite according to claim 1, wherein the step of estimating the strength of the reinforced resin composite after the wet heat treatment includes estimating a bending strength measured in accordance with ASTM D790.

13. A strength evaluation method for estimating the strength of a reinforced resin composite material containing a synthetic resin and a glass composition after a moist heat treatment, comprising: The strength of the reinforced resin composite material before the wet heat treatment; and The strength of the synthetic resin alone before the wet heat treatment; The strength of the synthetic resin alone after the moist heat treatment; and an adhesion rate of the synthetic resin to the glass composition in the reinforced resin composite before the moist heat treatment; and Based on the adhesion rate of the synthetic resin to the glass composition in the reinforced resin composite material after the moist heat treatment, A method for evaluating the strength of a reinforced resin composite material, comprising estimating the strength of the reinforced resin composite material after the moist heat treatment.

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