WO2002071056A1

WO2002071056A1 - Component comprising a humidity indicator

Info

Publication number: WO2002071056A1
Application number: PCT/DE2002/000726
Authority: WO
Inventors: Dirk Lukowsky; Ingo Hartung
Original assignee: Fraunhofer-Gesellschaft zur Förderung der angewandten Forschung e.V.
Priority date: 2001-03-03
Filing date: 2002-02-28
Publication date: 2002-09-12
Also published as: DE20103745U1; DE10290857D2

Abstract

The invention relates to a component, characterised by an optical humidity indicator that is fixed in or on a surface of said component. The indicator forms the closure for a tube that is introduced into the component, whereby the open internal end of said tube, opposite to the humidity indicator, projects into the area of the component that is to be monitored for humidity.

Description

COMPONENT WITH HUMIDITY INDICATOR

The invention relates to a component of a construction consisting at least partially of wood, wood-based materials, mineral building materials and / or insulating materials.

One of the most common causes of damage to building structures is excessive material moisture. In the case of wooden constructions, high levels of moisture in the wood cause the wood to swell and change its shape, which can lead to failure before the planned service life, particularly with dimensionally stable components such as windows and doors. At wood moisture levels above approx. 25%, an attack by wood-discoloring and wood-destroying fungi is also possible. Insulating materials lose their insulating effect due to excessive material moisture. Mineral building materials can also be damaged when exposed to moisture.

Inadmissibly high material moisture levels are often only recognized in the event of damage. If e.g. B. wood-destroying fungi on windows have already settled at this time, components such. B. Windows are often replaced within 5 years of installation.

Wood moisture is usually determined using electrical methods based on the resistance principle or using capacitive measuring devices. The moisture of mineral building materials can also be determined chemically. Other methods use microwaves, gamma rays or magnetic resonance imaging. The invention has for its object to provide an economically feasible way to monitor inner areas of components with respect to critical limits of relative humidity.

Starting from the component described at the outset, this object is achieved according to the invention by an optical moisture indicator attached in or on a component surface, which forms the end of a tube inserted into the component, the inner end of which is opposite the moisture indicator and which is to be monitored for its moisture content Component area protrudes.

The invention is characterized in particular by a moisture indicator which reacts with a color change from a certain relative air humidity.

The use of color indicators for moisture monitoring is already known when monitoring the water content of drying agents, e.g. As silica gel, for monitoring the moisture during transport and as a control of the water content in hydraulic oils. Cobalt salts or lead compounds are used as color indicators. However, these compounds already form a hydration shell in the presence of a relative air humidity <65%, change their color and are therefore not suitable for monitoring critical component moisture levels in the range from 85% to 100% relative air humidity.

The tube provided according to the invention ensures that only the relative humidity is monitored in the area into which the open inner tube end protrudes. To prevent moisture To prevent the outer tube end, but at the same time to ensure an unobstructed visual control of the moisture indicator, it is expedient if the outer end of the tube facing the viewer is sealed with a cover glass.

In a special embodiment, it is possible for the cover glass to be provided on its inside facing the open tube end with a coating which changes color at a certain relative atmospheric humidity.

A modified embodiment is characterized in that the moisture indicator contains salts or sugars that are transparent at a certain relative humidity by pulling water, e.g. B. become fluid.

Furthermore, it is possible for the moisture indicator to comprise a carrier material coated with hygroscopicity defined by salts.

In an expedient embodiment, the colored background can be formed by a colored elastic and porous material which is not or only slightly hygroscopic, but is capable of absorbing the foreground that has become fluid and z. B. can consist of a plastic foam or acetylated cellulose. The colored background formed in this way is preferably non-positively fixed in the tube and is clamped in the tube, for example, based on the inside diameter of the tube, and can at the same time thereby fix the salt plate forming the foreground in its position. The salt plate can basically consist of loose salt, which is held in position between the cover slip and the colored background. However, it is cheaper if the salt plate is made of pressed or melted material, since the foreground does not slip and the amount of salt can be selected very precisely.

The lower the amount of hygroscopic substance, the faster the colored background becomes visible. In order to cover the colored background completely while at the same time reacting at the highest possible speed, it is expedient if the salt plate comprises approximately 0.0007 to 0.0014 g / mm ^{2 of} the background to be covered.

The substance that forms the salt plate is said to have a steep course of the sorption isotherm. Only when the target moisture is present should the substance quickly draw water and lead to the dissolving of the foreground. Suitable substances for forming the foreground or the salt plate defining them are ammonium chloride, glucose, zinc sulfate, magnesium sulfate, sodium sulfate or oxalic acid, which dissolve at a relative humidity of 82% (ammonium chloride) to 96% (oxalic acid).

It can also be expedient if the salt plate has regions of salts with different sorption isotherms. This enables a rough differentiation of the actual moisture. It would be possible, for. B. an embodiment in which a small circle segment of the salt plate consists of ammonium chloride, which becomes liquid after about 15 days with a tube length of about 5 cm and a relative humidity of 82%, and in its loading makes the colored background visible. In this embodiment, the resulting wood moisture of about 15% would not be problematic; however, it is a first indication that this component, e.g. B. windows, may be exposed to increased moisture and therefore requires more frequent control. The remaining area of the salt plate could e.g. B. consist of sodium sulfate, which would only become liquid at an approximately 15-day exposure to 93% relative humidity. This would correspond to about 22% wood moisture and would therefore be a clear indication that an impermissible moisture penetration has taken place, which must be prevented.

In order to obtain a fast and exact moisture display, it is expedient if the optical moisture indicator has a control element which triggers a pushing, pulling or torsion movement when exposed to moisture, which is arranged in the tube in front of its rear end and mechanically changes the color of the moisture indicator under the influence of moisture triggers.

Further embodiments and features of the invention are the subject of the subclaims and are explained in more detail using exemplary embodiments.

Some exemplary embodiments of the invention are shown schematically in the drawing. Show it

1 shows a cross section through the lower wooden frame profile of a window frame with built-in moisture indicator; Figure 2 in cross section an insulating material including component with built-in moisture indicator;

Figures 3 to 7 on a greatly enlarged scale compared to Figures 1 and 2 five embodiments for a moisture indicator, each in longitudinal section;

FIG. 8 shows a longitudinal section through a moisture indicator, specifically in the illustration according to a) with a prestressed spring element which is in the rest position and which is shown in its active position in the illustration according to b);

Figures 9 to 1 1 modified embodiments in a representation according to Figure 8 a) and b);

Figure 12 shows a further modified embodiment in a representation according to Figure 8 a) and b), wherein the representations c) to f) show different displays of a colored display element, and

Figures 13 and 14 two further modified embodiments each in a representation according to Figure 8 a) and b). FIG. 1 shows as a component a window frame 1 made of wood, on the surface 1a of which preferably faces the inside of the room, an optical moisture indicator 2 is attached, which forms the end of a tube 3 inserted into the window frame 1. This tube 3, which can be made of plastic, cardboard, glass or metal (preferably aluminum or stainless steel), projects with its open inner end 3a opposite the moisture indicator 2 into the component area to be monitored with regard to its moisture.

FIG. 2 shows a component 5 including insulating material 4, on the surface 5a of which an optical moisture indicator 2 is fastened, the tube 3 of which projects with its open inner end into the insulating material 4 to be monitored with regard to its moisture.

Figure 3 shows in longitudinal section the outer portion of a tube 3, which is equipped with a moisture indicator 2. The outer end of the tube 3 is provided with a collar 6 which is thickened in the shape of a mushroom, with a cover glass 7 resting on the inwardly projecting ring flange-shaped edge 6a thereof, while the collar 6 lies with its outer edge on the component surface when the tube 3 is inserted into a component.

The cover glass 7 comprises two cover glasses 7a, 7b enclosing an air gap 8 between them, of which the inner cover glass 7b is provided on its inner side facing the open tube end 3a with a coating 9 which, at a certain relative air humidity, preferably from about 85% to 95% changes color. This coating 9 stands over the open end 3a of the tube with the component area to be monitored with regard to its moisture 3 in an air-exchange connection. The color change of the coating results, for. B. with certain chemicals due to a pH shift when exposed to moisture or the formation of a hydraulic envelope.

The diameter of the tube 3 can be between 3 mm and 25 mm, but preferably between 5 mm and 12 mm.

In the embodiment according to FIG. 4, instead of the coating 9 (FIG. 3) which changes its color under the influence of moisture, a salt plate 10 consisting of salts defined hygroscopicity is provided, the salts of which draw water at the atmospheric humidity to be displayed according to the invention and thereby become transparent or liquefy. A colored background 11 is provided behind this salt plate 10, which preferably consists of a plastic film provided with air exchange slits with UV-resistant coloring. The colored, preferably red, background 11 previously covered by the opaque dry salt of the salt plate 10 thus only becomes visible at a certain relative atmospheric humidity which leads to the transparency of the salts or to their dissolution.

FIG. 4 also shows that the salt plate 10, together with the colored background 11, is fixed in punctiform spacers 12, of which only three are preferably provided on the inner circumference of the tube in order to allow the air exchange between the open inner tube end 3a and the salt plate 10 as possible little to hinder. The sorption characteristics of numerous salts that are suitable for the salt plate 10 can be found in the relevant literature (for example, Kohlrausch "Practical Physics", Volume 3, BG Teubner Verlag, Stuttgart, 1986).

The embodiment according to FIG. 5 differs from that according to FIG. 4 only in that the cover glass 7 comprises a hollow chamber sealing ring 13, which seals the cover glasses 7a, 7b against the inner lateral surface of the tube 3.

In the embodiment according to FIG. 6, the moisture indicator comprises two transparent foils 14, 15 which are arranged one behind the other and are displaceable relative to one another and each provided with a stripe structure and which are acted upon by a control member 16 which has a moisture-dependent expansion. This control member 16 can, for. B. be a gel point with moisture-dependent swelling, which then causes the relative displacement mentioned. The control member can also be composed of a layer of swellable material and a layer of non-swellable material, so that the control member reacts to changes in moisture like a bimetallic strip to changes in temperature. In principle, such a relative shift could also be caused by a moisture-dependent elongation of horse tail hair. The relative displacement between the transparent films provided with stripe structure or comparable structures leads to the formation of characteristic optical structures. However, FIG. 6 also shows another possibility, namely the additional arrangement of a colored background 11, on which the view is only released when the relative shift has taken place.

The color change can also take place by releasing a salt plate of defined hygroscopicity or by moving a strip of two materials with very different sources that reacts to the change in moisture analogously to a bimetallic strip, triggering a color plate that is biased by a spring, which causes the color change.

In the exemplary embodiment shown in FIG. 7, a cover glass 7 covering the tube 3 on the outside is provided in the form of a cover plate. The colored background 11 is formed by a colored plastic sponge, which is clamped in the tube 3 and, together with the cover plate mentioned, fixes a salt plate 10 forming the foreground in its position.

Figure 8 a) shows in longitudinal section an optical moisture indicator 2 which has a plate 17 consisting of salt or sugar defined hygroscopicity, which is fixed in the tube 3 in front of its inner end 3a and forms an abutment for a prestressed element 18 which forms with its is supported at the rear end on an abutment 19 facing the inner tube end 3a and with its front end in its inactive position on the aforementioned plate 17 and upon its dissolution a cylindrical display element 20 which is axially displaceably mounted in the tube 3 through a film 21 into the Visible range of coverslip 7 closing the front end of tube 3 shifts. The front forehead area of the display element 20 z. B. be colored red and is applied by the biased element 18 by the z. B. pressed green colored film 21, so that the color visible through the cover glass 7 changes from green to red.

The modified embodiment shown in Figure 9 differs from that of Figure 8 only in that behind the cover glass 7 in the tube 3, a display element 22 is pivotally mounted, which on its top facing the cover glass 7 z. B. is provided with a hologram, the color of which is caused by a pressure element 23 caused by pivoting z. B. 20 ° for the viewer of z. B. changed green to red.

In the exemplary embodiment according to FIG. 10, the prestressed element 18 is supported with its front end on an abutment 24 of the tube 3 and with its rear end in its inactive position on the aforementioned plate 17. When the plate 17 dissolves, the prestressed element 18 can expand to the rear and thereby rotates a spherical colored display element 26 which is rotatably mounted behind the cover glass 7 and which thereby rotates by z. B. is rotated 180 °, so that instead of the initially visible, for. B. green colored page z. B. red colored side of the display element 26 is visible.

In the embodiment shown in FIG. 1 1, the arrangements of the plate 17 and the prestressed element 18 correspond to the embodiment according to FIGS. 8 a) and b). When the plate 17 is dissolved by the action of moisture, the front end of the prestressed element 18 now displaces a cylindrical one in the tube 3 axially displaceably mounted display element 27, which is thereby pressed out of the component surface 5a by 3 mm to 8 mm with its front end 27a, which is colored on its peripheral region. The signal color that becomes visible as a result, together with the suddenly protruding cover 28 covering the front end of the display element 27, signals a critical atmospheric humidity inside the component.

In the illustration according to FIG. 12 a), b), a torsion spring 29 is provided as the prestressed element, which is locked with its rear end on the rear abutment 19 and with its front end in its inactive position on the aforementioned plate 17 and upon its dissolution a colored circular disc-shaped display element 30 arranged behind the cover glass 7 in the tube 3 is rotated about its central axis in the sense of the arrows shown. The display element 30 can have certain colors on its upper side facing the cover glass 7, which colors become visible when the display element 30 is rotated through transparent fields of the cover glass 7. This can result in a color change of up to 50% of the

Guide the visible surface, the required twist angle is approximately 45 °. A color change of 100% can be achieved by the background being pushed completely in front of the foreground by a 360 ° torsion.

FIG. 13 shows a moisture indicator 2 which has neither a salt plate 10 which becomes transparent under the influence of moisture nor a plate 17 which dissolves under the influence of moisture, but is exclusively equipped with a torsion spring 29 which consists of spirally arranged swellable fibers 31 and with its rear end is locked to the abutment 19 of the tube 3 and its front end is connected to a disc-shaped colored display element 30 rotatably mounted behind the cover glass 7 in the tube 3. A typical example of this torsion spring is rotating wood, which causes torsion when the humidity changes. However, swellable fibers of z. B. hemp or flax can be used.

In the moisture indicator according to FIG. 14, a swelling body 32 which increases its volume under the influence of moisture is provided as a control element, which rests with its front end against the abutment 24 of the tube 3 and with its rear end via a pulling element 25 a spherical one, behind the cover glass 7 in Tubes 3 rotated colored display element 26 rotated. The source body 32 may e.g. B. consist of wood, bentonite or certain gels. Due to the expansion, the spherical display element 26 is successively rotated with the aid of a tensile stress, so that instead of the initially only visible, e.g. B. green colored side a red colored side of the ball gradually becomes increasingly visible.

Claims

claims

1 . Component of an at least partially made of wood, wood-based materials, mineral building materials and / or insulating materials (4), characterized by an optical moisture indicator (2) attached in or on a component surface (1 a, 5a), which indicates the completion of a Component (1) forms inserted tube (3) which, with its open inner end (3a) opposite the moisture indicator (2), projects into the component area to be monitored with regard to its moisture.

2. Component according to claim 1, characterized by a moisture indicator (2) which reacts with a color change from a certain relative humidity.

3. Component according to claim 1 or 2, characterized in that the outer end of the tube (3) facing the viewer is closed with a cover glass (7).

4. Component according to claim 3, characterized in that the cover glass (7) rests with its outside against an inwardly projecting flange edge (6a) of the tube (3).

Component according to claim 3 or 4, characterized in that the cover glass (7) comprises two cover glasses (7a, 7b) enclosing an air gap (8) between them.

6. Component according to claim 5, characterized in that the cover glass (7) comprises a hollow chamber sealing ring (13). (Figure 5)

7. Component according to one of claims 2 to 6, characterized in that the cover glass (7) on its inner side facing the open tube end (3a) is provided with a coating (9) which changes its color at a specific relative humidity. (Figure 3)

8. Component according to one of claims 2 to 6, characterized in that the moisture indicator (2) contains salts or sugars which are transparent at a certain relative humidity by pulling water, for. B. become fluid.

9. Component according to claim 8, characterized in that a colored background (1 1) is provided behind a layer facing the viewer from said salts or sugar which become transparent at a certain relative atmospheric humidity.

10. Component according to claim 9, characterized in that said layer is formed by a salt plate (10) consisting of salts of defined hygroscopicity.

1 1. Component according to claim 9 or 10, characterized in that the colored background (1 1) consists of a plastic film provided with air exchange slots.

12. Component according to claim 9, 10 or 1 1, characterized by a UV-resistant coloring of the background (1 1).

13. Component according to claim 10, 1 1 or 12, characterized in that the salt plate (10) together with the colored background (1 1) is fixed in punctiform spacers (12). (Figures 4 and 5)

14. Component according to one of claims 2 to 6, characterized in that the moisture indicator comprises two transparent foils (14, 15) which are arranged one behind the other and are displaceable relative to one another and each provided with a stripe structure, which for their relative displacement from a control member having a moisture-dependent expansion ( 16) are applied.

15. Component according to claim 14, characterized in that said control member (16) is a gel point with moisture-dependent swelling.

16. Component according to one of claims 2 to 6, characterized in that the moisture indicator (2) comprises a carrier material coated with salts defined hygroscopicity.

17. Component according to one of claims 10 to 13, characterized in that the colored background (1 1) is formed by a colored elastic or porous material which is not or only slightly hygroscopic.

18. Component according to claim 17, characterized in that the colored background (1 1) consists of a plastic foam or acetylated cellulose.

19. Component according to claim 17 or 18, characterized in that the colored background (1 1) is non-positively fixed in the tube (3).

20. Component according to claim 17, 18 or 19, characterized in that the colored background (1 1) fixes the salt plate (10) forming the foreground in its position.

21. Component according to one of claims 17 to 20, characterized in that the salt plate (10) consists of pressed or molten material.

22. Component according to one of claims 17 to 21, characterized in that the salt plate (10) has regions of salts with different sorption isotherms.

23. Component according to one of claims 17 to 22, characterized in that the salt plate (10) comprises approximately 0.0007 to 0.0014 g / mm ^{2 of} the background (11) to be covered.

24. Component according to one of claims 1 to 6, characterized in that the optical moisture indicator (2) has a defined by salt or sugar hygroscopicity existing plate (17) which is fixed in the tube (3) in front of its inner end (3a) and an abutment for a preloaded el ment (18), which mechanically triggers a color change of the moisture indicator (2) when the platelet (17) dissolves under the influence of moisture.

25. The component according to claim 24, characterized in that the prestressed element (18) with its rear end on an abutment (19) facing the inner tube end (3a) and with its front end in its inactive position on said plate (17 ) supports and when it dissolves, a colored display element (20) is moved through a film (21) into the visible area of the cover glass (7). (Figure 8)

26. Component according to claim 24, characterized in that the prestressed element (18) with its rear end on an abutment facing the inner tube end (3a)

(19) and with its front end in its inactive position on the said plate (17) and, when it is dissolved, a colored display element via a pressure element (23)

(20) pivoted, which is pivotally mounted behind the cover slip (7) in the tube (3). (Figure 9)

27. The component according to claim 24, characterized in that the prestressed element (18) is supported with its front end on an abutment (24) of the tube (3) and with its rear end in its inactive position on the said plate (17) and upon its dissolution, a spherical colored display element (26) rotatably mounted behind the cover glass (7) is rotated via a pulling element (25). (Figure 10)

28. Component according to claim 24, characterized in that the prestressed element (18) with its rear end on an abutment (19) facing the inner tube end (3a) and with its front end in its inactive position on said plate (17 ) supports and when it dissolves, it presses a cylindrical display element (27) axially displaceably mounted in the tube (3) with its front end (27a), which is colored on its circumferential area, out of the component surface (5a). (Figure 1 1)

29. Component according to claim 24, characterized in that the prestressed element is a torsion spring (29), the rear end of which rests on an abutment (19) facing the inner tube end (3a) and the front end thereof in its inactive position is locked on said plate (17) and when it is dissolved, a colored circular disk-shaped display element (30) arranged behind the cover glass (7) in the tube (3) is rotated about its central axis. (Figure 12)

30. The component according to one of claims 1 to 6, characterized in that the optical moisture indicator (2) has a control element which triggers a pressure, tensile or torsional movement when exposed to moisture and is arranged in the tube (3) in front of its rear end (3a) is and mechanically triggers a color change of the moisture indicator (2) under certain humidity.

31. Component according to claim 30, characterized in that said control element is a torsion spring (29) which consists of spi- rallell arranged swellable fibers (31) and locked with their rear end to an abutment (19) of the tube (3) and with its front end with a disc-shaped colored display element rotatably mounted behind the cover glass (7) in the tube (3) (30) communicates. (Figure 13)

32. Component according to claim 30, characterized in that said control element is a swelling body (32) which increases its volume under the influence of moisture and which bears with its front end against an abutment (24) of the tube (3) and with its rear end a pulling element (25) rotates a spherical colored display element (26) which is rotatably mounted in the tube (3) behind the cover glass (7).

(Figure 14)