JP5584656B2 - Method for determining mold resistance of building materials - Google Patents

Description

  The present invention relates to a method for determining mold resistance of building materials.

  In recent years, the living environment has become more sealed. For this reason, mild condensation occurs due to a slight temperature difference from the outside air temperature or water vapor generated by human life and the like, which may cause problems in terms of hygiene and comfort.

  As a method for mold prevention test of building materials, inoculate mold surface on the building material and incubate under the conditions close to the actual building environment, which is reproduced in a full-scale building and constant temperature / humidity chamber, It has been proposed to conduct a mold prevention test for building materials (see Non-Patent Document 1, for example). In addition, a method has been proposed in which mold is inoculated on a test piece of building material, cultured on a medium in a petri dish, and a mold prevention test is performed (see, for example, Non-Patent Documents 2 and 3).

  On the other hand, mold is known to hardly grow at high pH. For example, Patent Document 1 discloses 0.1 to 10 aluminosilicate mineral fine powders having a pH value of at least 11.0 or more, a base substitution capacity (meq / 100 g) of 80 mg or more, and a particle size of 2 μm or less. 0.0% by weight of alkaline ionized water is sprayed into the building space and volatilized organic compounds and odorous gases that are volatilized and retained are decomposed and erased. In addition, a method for purifying a building space characterized by drying is disclosed.

JP 2003-70889 A

Fumiharu Saito, Toshifumi Yoshikawa, Journal of Japan Society for Finishings Technology, FINEX, 2 (4), 70-77, 1990. Japanese Standards Association, JIS Z 2911 Mold Resistance Test Method Akira Oshima, Isamu Matsui, Summary of Academic Lectures of Architectural Institute of Japan, Materials and Construction Volume, p. 1173, 1992

  However, in the method described in Non-Patent Document 1, it takes time to determine the mold resistance of building materials, and it may take several tens of days. In addition, the method of Non-Patent Document 2 is a standard for a single building material, cannot be determined on site because it is necessary to prepare a sample, requires experimental equipment to handle mold spores, and increases the mold resistance of building materials. There were problems such as taking days to make a decision. Therefore, according to the present invention, it is not necessary to cut out the building material for the mold resistance of the building material regardless of whether the building material is a single material or a composite material. It is an object to provide a method for simple and easy determination.

  The present invention includes a pH measurement step for measuring the pH of the surface of the building material, and a determination step for determining that the mold material has high mold resistance when the pH measured in the pH measurement step is a predetermined value or more. A method for determining mold resistance is provided.

  According to the present invention, it is not necessary to cut out the building material regardless of whether the building material is a single material or a composite material. It can be easily determined by time.

  The building material may be a composite material. The composite material is a building material in which various types and materials of building materials are not formed as a single unit but are formed into a plurality of layers, and generally includes a base material and a finishing material. Composite materials are often used for the interior of buildings. As will be described later, according to the present invention, the mold resistance of building materials can be correctly determined not only for a single building material but also for such a composite material.

  The predetermined value is preferably pH 9. As will be described later, when the predetermined value is pH 9, the mold resistance of the building material can be determined more accurately.

  With the present invention, it is not necessary to cut out building materials regardless of whether the building material is a single material or a composite material. Can be provided.

1A and 1B are a top view and a cross-sectional view, respectively, of a jig according to an embodiment. 2A to 2D are graphs showing typical examples of changes with time of pH measured by an electrode method. 3A to 3D are graphs showing the results of Experimental Example 2. FIG. 4A and 4B are graphs showing the results of Experimental Example 5. FIG. FIG. 5 is a graph showing the results of Experimental Example 6.

  Hereinafter, preferred embodiments will be described with reference to the drawings as the case may be. In the description of the drawings, the same elements are denoted by the same reference numerals, and redundant description is omitted. In addition, the drawings are exaggerated for easy understanding, and the dimensional ratios do not necessarily match those described.

  The present invention includes a pH measurement step for measuring the pH of the surface of the building material, and a determination step for determining that the mold material has high mold resistance when the pH measured in the pH measurement step is equal to or higher than a predetermined value.

  First, the pH measurement step will be described. In one embodiment, the pH of the building material surface is measured with a pH electrode. While the pH is a value defined in the solution, the building material surface is usually dry. Therefore, a jig as shown in FIG. 1 is fixed to the surface of the building material, a predetermined amount of water is dropped into the jig to bring the surface of the building material into contact with water, and the pH of the water is regarded as the pH of the surface of the building material. taking measurement.

  Fig.1 (a) and (b) are one Embodiment of the jig | tool used when measuring the pH of the surface of building materials using a pH electrode. FIG. 1A shows a top view of the jig. FIG.1 (b) shows sectional drawing of the jig | tool in use. The jig 100 includes a main body 10 and an O-ring 20. The main body 10 is made of acrylic, for example, and a through hole is formed in the central portion. The jig 100 is fixed to the surface of the building material 200, and water 30 is dropped into the through hole of the jig 100. As water, for example, distilled water or ion exchange water can be used. The amount of water is preferably 0.5 to 2 mL, and more preferably 1 to 2 mL. If the amount of water is less than 0.5 mL, it may be difficult to immerse the pH electrode in water. Moreover, water may be absorbed from the building material surface in a short time, and it may be difficult to measure pH. On the other hand, if the amount of water is too large, the pH of the building material surface may not be accurately measured. The amount of water is preferably as small as possible within the range where pH measurement is possible. The pH electrode is immersed in the water 30 brought into contact with the building material, and the pH of the water is regarded as the pH of the building material surface and measured. As the pH electrode, since it is possible to measure pH even with a small amount of water, a plane glass composite glass electrode (plane electrode) is suitable.

  As will be described later, the inventors have found that when pH is measured by the above method, there is a time difference from the start of measurement until the pH value is stabilized. In most building materials, the pH value stabilizes in about 5 minutes after the pH measurement is started immediately after the water is dropped. Therefore, it is preferable that the measured value on the surface of the building material starts the pH measurement immediately after dropping water, and the value after 5 to 15 minutes from the start of the measurement is the measured value of pH. However, in the case of a building material with high water absorption, such as a calcium plate, water dripped inside the jig may be absorbed by the building material and pH measurement may not be possible within a few minutes from the start of measurement. In such a case, the final measured value may be the pH value of the building material surface.

  In one embodiment, the pH of the building material surface is measured based on a change in the color of the indicator by applying a pH indicator to the building material surface.

  As the pH indicator, those whose color changes around pH 9 are preferable. For example, thymol blue, phenolphthalein, thymolphthalein, or a mixture of two or more of these pH indicators can be used. As the pH indicator, a pen filled with a pH indicator which is commercially available as a tester pen may be used.

  In one embodiment, the pH of the building material surface is measured as follows. First, distilled water is dropped on the surface of the sample to wet the surface, and then wiped off with a wiper such as Kimwipe (trade name, manufactured by Nippon Paper Crecia). Subsequently, a pH indicator is applied to the wet part of the building material surface. After tens of seconds to 1 minute, the color of the indicator is converted to a pH value by checking with a color sample.

  Next, the determination step will be described. In the determination step, when the pH measured in the pH measurement step is equal to or higher than a predetermined value, it is determined that the mold resistance of the building material is high. The predetermined value is preferably pH 9, more preferably pH 10, and still more preferably pH 11. If the pH of the building material surface is 9 or more, it can be determined that the mold resistance of the building material is high.

  EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples of the present invention. However, the present invention is not limited to these examples, and various modifications can be made without departing from the technical idea of the present invention. Can be changed.

  The following experiments were performed on various building materials of Samples 1 to 24 shown in Table 1. Samples 1 to 16 were composite materials, and Samples 17 to 24 were single building materials. The composition of the composite material is as shown in Table 1. For example, Sample 1 was a composite material having a gypsum board as a base material and a cloth A containing no fungicide as a finishing material. In Table 1, “calcal plate” and “flexible plate” are abbreviations for calcium silicate plate and flexible plate, respectively. The details of each base material and finishing agent are shown in Table 2. When bonding the cloth A or the cloth B to the base material, the cloth adhesive shown in Table 2 was used.

(Experimental example 1)
(Measurement of pH on building material surface using pH electrode)
The pH of the surfaces of Samples 1 to 22 was measured using a pH electrode. First, the surface of the sample was cleaned with compressed air. Subsequently, an acrylic jig similar to that shown in FIG. 1 was fixed to the surface of the sample. In the case of a sheet-like sample having almost no thickness, an acrylic plate was applied to the back side of the sample. Subsequently, 1000 μL of distilled water was gently dropped from the gap above the jig using a micropipette. Immediately after the dropwise addition of distilled water, the pH electrode was brought into contact with distilled water, and the pH of the distilled water was measured every minute until 15 minutes later. Hereinafter, the pH measurement method by this method may be referred to as “electrode method”. About sample 23 and 24, after apply | coating on an acrylic board and making it dry, pH of the dried coating film was measured similarly to samples 1-22.

(Change in pH over time)
2A to 2D are graphs showing typical examples of changes with time of pH measured by an electrode method. 2 (a) to 2 (d) show the results when (a) sample 1, (b) sample 12, (c) sample 14 and (d) sample 19 are measured as building materials, respectively. Most building materials showed stable pH values in about 5 minutes. The measured value of pH 15 minutes after the start of measurement was defined as the pH of the sample surface. In some cases, the sample containing a calcium plate that easily absorbs water could not measure the pH until after 15 minutes. For samples whose pH could not be measured until after 15 minutes, the final value that could be measured was taken as the measured pH value. The measurement result of pH by the electrode method was used in Experimental Example 5.

(Experimental example 2)
(Examination of the effect of the base material on the pH of the composite surface)
The influence of the base material on the pH of the surface of the composite material was examined. 3A to 3D summarize the results of Experimental Example 1, and are graphs showing the influence of the base material on the pH of the surface of the composite material.

  Each of FIGS. 3A to 3D is a sample of only a plaster board, water-resistant gypsum, a calcium plate and a flexi plate, and these are used as a base material, and a cloth A (FIG. 3A) and cloth Measure the pH of composite samples having B (FIG. 3 (b)), paint A (FIG. 3 (c)) and paint B (FIG. 3 (d)) as finish materials, and samples of these finish materials only. It is the result. More specifically, the graph of FIG. 3A shows the measurement results of the pH of samples 17, 1, 18, 5, 19, 9, 20, 13 and 21 in order from the left. Moreover, the graph of FIG.3 (b) is a measurement result of pH of the sample 17, 2, 18, 6, 19, 10, 20, 14 and 22 in an order from the left. Moreover, the graph of FIG.3 (c) is a measurement result of pH of the samples 17, 3, 18, 7, 19, 11, 20, 15 and 23 in an order from the left. Moreover, the graph of FIG.3 (d) is the measurement result of pH of the sample 17, 4, 18, 8, 19, 12, 20, 16 and 24 in an order from the left.

  As a result, it has been clarified that the pH of the surface of the composite material is affected not only by the finishing material but also by the base material. Therefore, in order to accurately determine the mold resistance of the building material, it is considered necessary to consider the influence of the base material as well as the finishing material.

(Experimental example 3)
(Mold resistance test)
Samples 1 to 21 shown in Table 1 were tested for mold resistance. The test was performed according to “ISO 846: 1997, plastic product, method A” (hereinafter sometimes referred to as “ISO A method”). Specifically, samples 1 to 21 were placed on an inorganic agar medium in a petri dish, and bacteria (Aspergillus niger, Penicillium pinophyllum, Ketomium globosum, Trichoderma bilens, Cladosporium cladosporiides, Pesilomyces) A suspension of variot) (inorganic salt aqueous solution to which N-meryl taurine was added, spore concentration of 10 ⁶ CFU / mL) was dropped evenly over the sample and the medium with a total of 0.1 mL each using a syringe for 4 weeks or In some cases, the cells were cultured for 8 weeks, and the extent of mold growing on the sample was determined by 4 levels of determination values from 0 to 3. A judgment value of 0 has the highest mold resistance. The determination result was used in Experimental Example 5. The criteria for the judgment value were as follows.
0: No development of mycelia.
1: The growth of mycelia was confirmed under a microscope.
2: Mycelial growth was observed in less than 25% of the total area of the sample.
3: Mycelial growth was observed in 25% or more of the total area of the sample.

(Experimental example 4)
(Measurement of pH on building material surface using pH indicator)
The pH of the surfaces of Samples 1 to 22 was measured using a tester pen (Astro pH tester pen WS, trade name, Nikken Chemical Laboratory Co., Ltd.). First, a few drops of distilled water were dropped on the surface of the sample to wet the surface. Subsequently, water on the surface of the sample was wiped off with a wiper, and a tester pen reagent was applied to the wet part of the surface. After 30 to 60 seconds, the pH was measured by comparing with the color sample. Hereinafter, the pH measurement method by this method may be referred to as “indicator method”. The measurement result of the pH of the building material surface by the indicator method was used in Experimental Example 5. About sample 23 and 24, after apply | coating on an acrylic board and making it dry, pH of the dried coating film was measured similarly to samples 1-22.

(Experimental example 5)
(Comparison of measured values of pH on building material surfaces by electrode method and indicator method)
The measured value of the pH by the electrode method and the indicator method on the surface of the building materials of Samples 1 to 21 was compared with the result of the mold resistance test. 4A and 4B are graphs showing the results of Experimental Example 5. FIG. Whether measured by the electrode method or the indicator method, the building material has a high mold resistance when the building material surface has a pH of 9 or more, regardless of whether the building material contains a fungicide or not. It has been shown. Therefore, if the pH of the building material surface is 9 or more, it can be determined that the mold resistance of the building material is high.

(Experimental example 6)
(Measurement of pH of building materials by crushing method)
Each of the flexi plate (sample 20), flexi plate and cloth A composite material (sample 13), flexi plate and paint A composite material (sample 15), cloth A (sample 21) and paint A (sample 23) The pH was measured by a crushing method. The crushing method is a method in which building materials are crushed and suspended in water, and the pH of the water is measured with a pH electrode. Specifically, the measurement was performed as follows. First, the building material was pulverized with a pulverizer and a mortar, and 1 g of the obtained sample was put in a beaker. Next, 100 mL of distilled water was added to this beaker and gently stirred with a stirrer to obtain a suspension of building materials. Subsequently, the pH of the suspension was measured with a pH electrode while stirring with a stirrer. About the coating material A, after apply | coating on the board made from a polytetrafluoroethylene and making it dry, the dried coating film was peeled off and it was set as the sample.

  FIG. 5 is a graph showing the results of Experimental Example 6. Unlike the measured value of the surface pH of the composite material by the electrode method in Experimental Example 2, the measured value of the pH of the composite material by the crushing method was almost the same as that of the base material. This is presumed to be because the base material occupies a large volume of the sample in the measurement of the pH of the composite material by the crushing method. Therefore, in order to determine the mold resistance of a building material, an electrode method or an indicator method that is considered to more accurately reflect the pH of the surface of the building material is considered suitable.

DESCRIPTION OF SYMBOLS 10 ... Main body, 20 ... O-ring, 30 ... Water, 100 ... Jig, 200 ... Building material.

Claims (3)

Fixing a jig having a through hole to the building material surface, dropping water into the jig, bringing the building material surface into contact with water through the through hole, and measuring the pH of the water as the pH of the building material surface Measuring steps;
When the pH measured in the pH measurement step is a predetermined value or more, a determination step for determining that the mold material has high mold resistance;
A method for determining mold resistance of building materials.   The method of claim 1, wherein the building material is a composite material.   The method according to claim 1, wherein the predetermined value is pH 9.

Images