Method for detecting curing of the binder in a mineral fiber product

Abstract

The present invention relates to a method for detecting curing and/or the local distribution of curing of the binder material, in particular for detection of anomalies of the cured binder, in a mineral fiber product. The present invention also relates to a reagent, in particular for use in such a method and the use of this reagent in the quality control of bonded mineral fiber products.

Claims

1. A method for detecting curing in a mineral fiber product which comprises mineral fibers bonded together with a cured or partly cured thermoset binder, wherein the method comprises bringing the mineral fiber product into contact with a liquid mixture comprising one or more fluorescent compounds and detecting an intensity of fluorescence and/or a pattern of fluorescence or absence of fluorescence on one or more surfaces of the mineral fiber product and/or detecting a color change on one or more surfaces of the mineral fiber product.

2. The method of claim 1, wherein the one or more fluorescent compounds are selected from one or more of xanthenes, acridines, quinine, quinine derivatives, coumarins, aryl sulfonates.

3. The method of claim 1, wherein the method for detecting curing comprises detection of binder distribution anomalies in the mineral fiber product.

4. The method of claim 3, wherein the binder distribution anomalies comprise agglomeration of binder.

5. The method of claim 1, wherein the liquid mixture comprises a fluorescent compound in a concentration of from 0.001 to 1 wt.-%.

6. The method of claim 1, wherein the liquid mixture comprises a fluorescent compound in the form of a solution of from 0.001 to 1 wt.-% of fluorescein sodium salt in one of (1) an aqueous solution of up to 30 wt.-% of one or more C.sub.1 to C.sub.4 alcohols, (2) an aqueous solution of a detergent, (3) water.

7. The method of claim 6, wherein the liquid mixture comprises from 0.01 to 1 wt.-% of fluorescein sodium salt.

8. The method of claim 6, wherein the one or more C.sub.1 to C.sub.4 alcohols comprise ethanol and/or isopropanol.

9. The method of claim 1, wherein the mineral fiber product comprises mineral fibers bonded together by a cured or partly cured thermoset binder, the non-cured binder comprising a phenol-formaldehyde based resol and optionally, a sugar component.

10. The method of claim 1, wherein the mineral fiber product comprises mineral fibers bonded together by a cured or partly cured thermoset binder, the non-cured binder comprising (1) a water-soluble binder component obtainable by reacting at least one alkanolamine with at least one polycarboxylic acid or anhydride and, optionally, treating the reaction product with a base; (2) a sugar component; and optionally, (3) urea.

11. The method of claim 1, wherein the mineral fiber product comprises mineral fibers bonded together by a cured or partly cured thermoset binder, the non-cured binder comprising (a) a sugar component, and one or both of (b) a polycarboxylic acid component, and (c) a component selected from amine compounds, ammonia, ammonium salts of a polycarboxylic acids.

12. The method of claim 11, wherein the sugar component is selected from sucrose, reducing sugars, poly-carbohydrates, and mixtures thereof.

13. The method of claim 1, wherein the mineral fiber product comprises man-made vitreous fibers selected from stone fibers, mineral fibers, slag fibers, basalt fibers, glass fibers.

14. The method of claim 1, wherein bringing the mineral fiber product into contact with a liquid mixture comprising a fluorescent compound and detecting the intensity of fluorescence and/or the pattern of fluorescence and/or the absence of fluorescence on one or more surfaces of the mineral fiber product and/or detecting a color change on one or more surfaces of the mineral fiber product are performed immediately after curing and cooling of the binder in the mineral fiber product.

15. The method of claim 1, wherein detecting the intensity of fluorescence and/or the pattern of fluorescence on one or ore surfaces of the mineral fiber product and/or detecting a color change on one or more surfaces of the mineral fiber product takes place by visual inspection.

16. The method of claim 1, wherein detecting the intensity of fluorescence and/or the pattern of fluorescence on one or more surfaces of the mineral fiber product takes place under irradiation with UV light.

17. The method of claim 1, wherein the mixture comprising one or more fluorescent compounds is brought into contact with the mineral fiber product by spraying the liquid mixture onto one or more surfaces of the mineral fiber product.

18. The method of claim 1, wherein the mixture comprising one or more fluorescent compounds is brought into contact with one or more of the outer surfaces of the mineral fiber product.

19. The method of claim 1, wherein the mixture comprising one or more fluorescent compounds is brought into contact with a split surface of the mineral fiber product, the one or more split surfaces resulting from cutting the mineral fiber product.

20. A reagent for the detection of curing and/or binder distribution anomalies in a mineral fiber product, wherein the reagent comprises a solution of from 0.001 to 1 wt.-% fluorescein sodium salt in (1) an aqueous solution of from 1 to 30 wt.-% of one or more C.sub.1 to C.sub.4 alcohols or (2) an aqueous solution comprising a detergent.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) In the accompanying drawings,

(2) FIGS. 1-1 to 1-36 are photographs of samples obtained by the procedure described in Example 1 below;

(3) FIGS. 2-1 to 2-4 are photographs of samples obtained by the procedure described in Example 2 below;

(4) FIGS. 3-1 to 3-2 are photographs of samples obtained by the procedure described in Example 3 below;

(5) FIGS. 4-1 to 4-3 are photographs of samples obtained by the procedure described in Example 4 below;

(6) FIGS. 5-1 to 5-9 are photographs of samples obtained by the procedure described in Example 5 below;

(7) FIGS. 5-10 to 5-12 are photographs of samples obtained by the procedure described in Example 6 below; and

(8) FIG. 6 is a schematic representation of an embodiment of the method of the present invention.

EXAMPLES

(9) Binders were made for the Examples below.

(10) Binder: PUF-sugar

(11) This binder is a PUF-resol with sugar.

(12) A phenol-formaldehyde resin is prepared by reacting 37% aq. formaldehyde (606 g) and phenol (189 g) in the presence of 46% aq. potassium hydroxide (25.5 g) at a reaction temperature of 84 C. The reaction is continued until the acid tolerance of the resin is 4 and most of the phenol is converted. Urea (241 g) is then added.

(13) Using the urea-modified phenol-formaldehyde resin obtained, a binder is made by addition of 25% aq. ammonia (90 mL) and ammonium sulphate (13.2 g) followed by either water (1.80 kg), dextrose syrup with a DE value of 90-95 (Cargill) (370 g), and 40% aq. silane (Momentive VS-142) (3.1 g) or water (2.48 kg), dextrose syrup with a DE value of 90-95 (909 g), and 40% aq. silane (Momentive VS-142) (4.3 g).

(14) Binder: B1 and B1-urea-sugar

(15) This binder is based on alkanolamine-polycarboxylic acid anhydride reaction products.

(16) B1:

(17) Diethanolamine (DEA, 280 g) is placed in a 1-liter glass reactor provided with a stirrer and a heating/cooling jacket. The temperature of the diethanolamine is raised to 60 C. where after tetrahydrophthalic anhydride (THPA, 156 g) is added. After raising the temperature and keeping it at 130 C., a second portion of tetrahydrophthalic anhydride (78 g) is added followed by trimellitic anhydride (TMA, 156 g). After reacting at 130 C. for 1 hour, the mixture is cooled to 95 C. Water (231 g) is added and stirring is continued for 1 hour. After cooling to ambient temperature, the mixture is poured into water (1.90 kg) and 50% aq. hypophosphorous acid (12 g), 25% aq. ammonia (131 g) and 50% aq. silane (Momentive VS-142) (2.9 g) are added under stirring.

(18) B1-Sugar-Urea:

(19) Diethanolamine (DEA, 157 g) is placed in a 5-liter glass reactor provided with a stirrer and a heating/cooling jacket. The temperature of the diethanolamine is raised to 60 C. where after tetrahydrophthalic anhydride (THPA, 87 g) is added. After raising the temperature and keeping it at 130 C., a second portion of tetrahydrophthalic anhydride (44 g) is added followed by trimellitic anhydride (TMA, 87 g). After reacting at 130 C. for 1 hour, the mixture is cooled to 95 C. Water (315 g) is added and stirring is continued for 1 hour. Urea (281 g) is then added and stirring is continued until all solids are dissolved. After cooling to ambient temperature, the mixture is poured into water (3.66 kg) and 50% aq. hypophosphorous acid (6 g) and 25% aq. ammonia (55 g) are added under stirring. Dextrose syrup with a DE value of 90-95 (Cargill) (1.54 kg) heated to 60 C. is then added under stirring followed by 50% aq. silane (Momentive VS-142) (6.2 g).

Example 1: Detecting Model B1 and B1-Sugar-Urea Wet Spots with Fluorescent Dyes in Demineralized Water, Absolute Ethanol or Mixtures Thereof

(20) A range of fluorescent dyes in different concentrations (0.01-1.0%) and solvents (demineralized water, absolute ethanol, or mixtures thereof) were tested for their response to model wet spots.

(21) Small disc-shaped stone wool samples (diameter: 5 cm; height 1 cm) were cut out of stone wool and heat-treated at 580 C. overnight to remove all organics. Three spots of 0.5 mL B1 (no dextrose) or B1-sugar-urea (with dextrose) were made on each disc which were then dried at 105 C. for 30 min. The fluorescent dyes would give the same response on fully cured stone wool as on the heat-treated background on the model wet spot discs.

(22) Solutions of fluorescein, fluorescein sodium salt, 2,7-dichlorofluorescein, rhodamine B, rhodamine 6G, eosin Y disodium salt (2,4,5,7,-tetrabromofluorescein disodium salt), eosin B (4,5-Dibromo-2,7-dinitrofluorescein disodium salt), sulforhodamine B, acridine orange (3,6 bis(dimethylamino)acridine), acridine yellow G (2,7-dimethylacridine-3,6-diamine hydrochloride); tonic water (containing quinine), quinine hydrochloride dihydrate, umbelliferone (7-hydroxycoumarin), pyranine (8-hydroxypyrene-1,3,6-trisulfonic acid trisodium salt), were sprayed onto the stone wool discs with model wet spots and investigated under 365 nm UV-light, 254 nm UV-light and daylight.

(23) The results are seen in table 1:

(24) TABLE-US-00001 TABLE 1 Conc. Dye (%) Solvent Binder Detection Wet spot Background Cand..sup.a FIG. Fluorescein 0.01 Water or 20% EtOH B1-sugar-urea 254 nm Black Bright green ++ 1-01 sodium salt 0.01 Water B1 Daylight Medium gray Light green + 1-02 0.1 Water B1 365 nm Weak green Bright green + 1-03 0.1 Water B1 254 nm Black Bright green ++ 1-04 0.1 Water B1 Daylight Medium gray Light green + 1-05 1.0 Water B1 365 nm Bright green Weak green + 1-06 1.0 Water B1 Daylight Medium gray-green Medium brown + 1-07 2,7- 0.01 EtOH B1-sugar-urea 254 nm Black Medium green + 1-08 Dichlorofluorescein Rhodamine B 0.1 Water B1 365 nm Bright orange Weak orange + 1-09 0.5 Water or 20% EtOH B1-sugar-urea 365 nm Orange Dark brown + 1-10 1.0 Water B1 365 nm Bright red-orange Black ++ 1-11 Rhodamine 6G 0.01 water, 20% EtOH or EtOH B1-sugar-urea 254 nm Black Weak yellow + 1-12 0.1 Water B1 365 nm Bright yellow Weak yellow + 1-13 0.1 Water B1 Daylight Light green Light pink + 1-14 1.0 Water B1 365 nm Bright yellow-orange Black ++ 1-15 Eosin Y disodium 0.01 10% EtOH B1-sugar-urea 254 nm Black Weak green + 1-16 salt 0.1 10% EtOH B1-sugar-urea 254 nm Faint green Medium green + 1-17 Sulforhodamine B 0.1 10% EtOH B1-sugar-urea 254 nm Black Medium orange + 1-18 1.0 10% EtOH B1-sugar-urea 365 nm Bright orange Weak orange + 1-19 Acridine Orange 0.01 10% EtOH B1-sugar-urea 254 nm Weak green Medium green + 1-20 0.1 40% EtOH B1-sugar-urea 365 nm Black Weak green + 1-21 0.1 40% EtOH B1-sugar-urea 254 nm Black Medium green ++ 1-22 0.1 40% EtOH B1-sugar-urea Daylight Brown-orange Yellow-orange + 1-23 Acridine Yellow G 0.01 10% EtOH B1-sugar-urea 365 nm Black Faint blue-green + 1-24 0.01 10% EtOH B1-sugar-urea 254 nm Black Weak blue-green + 1-25 0.1 10% EtOH B1-sugar-urea 365 nm Faint blue-green Weak blue-green + 1-26 0.1 10% EtOH B1-sugar-urea 254 nm Black Weak blue-green + 1-27 Tonic water.sup.b B1-sugar-urea 254 nm Black Medium blue + 1-28 Umbelliferone 0.01 10% EtOH B1-sugar-urea 365 nm Weak blue Medium blue + 1-29 0.01 10% EtOH B1-sugar-urea 254 nm Black Medium blue ++ 1-30 0.1 10% EtOH B1-sugar-urea 254 nm Black Bright blue ++ 1-31 Pyranine 0.01 10% EtOH B1-sugar-urea 365 nm Bright green Medium green + 1-32 0.01 10% EtOH B1-sugar-urea 254 nm Weak green Medium green + 1-33 0.01 10% EtOH B1-sugar-urea Daylight Gray-brown Bright green + 1-34 0.1 10% EtOH B1-sugar-urea 254 nm Weak green Bright green + 1-35 0.1 10% EtOH B1-sugar-urea Daylight Gray-brown Bright green + 1-36 None (comparative 0 none B1-sugar-urea 254 nm Black Black comparative example) Key: .sup.a++: very good candidate; +: good candidate. .sup.bSoaked instead of spraying. Fluorescein sodium salt represented the most promising candidate in these studies as a result of high level of contrast at low concentration (0.01-0.1%), possibility for detection at both 254 nm UV-light and daylight, no dependence on dextrose content in binder, high solubility in water, low toxicity and low price.

Example 2: Detecting Model B1-Sugar-Urea Wet Spots with 0.01% Fluorescein Sodium Salt in Alternative Solvents

(25) The sensitivity of 0.01% fluorescein sodium salt spray towards the nature of the water and alcohol used was investigated:

(26) Small disc-shaped stone wool samples with three B1-sugar-urea (with dextrose) wet spots were obtained as described in example 1. Solutions of 0.01% fluorescein sodium salt in all six possible combinations of 20% absolute ethanol, denatured ethanol or isopropanol in deionized water or cold tap water were sprayed onto the stone wool discs with model wet spots and investigated under 254 nm UV-light and daylight. Results identical to those obtained in Example 1 were obtained with all solvent mixtures (FIG. 2-1 and FIG. 2-2 at 254 nm and FIG. 2-3 and FIG. 2-4 at daylight). No difference between the use of absolute ethanol, denatured ethanol or isopropanol in deionized water or cold tap water in sprays based on 0.01% fluorescein sodium salt.

Example 3: Detecting Model B1-Sugar-Urea Wet Spots with 0.01% Fluorescein Sodium Salt Water with 1-5% Detergent

(27) The possibility of substituting the use of alcohols with detergents to lower the surface tension of the spray was investigated:

(28) Small disc-shaped stone wool samples with three B1-sugar-urea (with dextrose) wet spots were obtained as described in Example 1. Solutions of 0.01% fluorescein sodium salt in water with 1% or 5% detergent were sprayed onto the stone wool discs with model wet spots and investigated under 365 nm UV-light, 254 nm UV-light and daylight. As a detergent Suma Star Free, JohnsonDiversey, and Ecolab Assert Clean were used and gave the same results.

(29) FIGS. 3-1 and 3-2 show the examples where Suma Star Free, JohnsonDiversey were used. Results identical to those obtained in Example 1 were obtained (FIG. 3-1 at 254 nm and FIG. 3-2 at daylight). 1% or 5% detergent can be used instead of 10-20% alcohol to lower the surface tension in sprays based on 0.01% fluorescein sodium salt.

Example 4: Detecting Model PUF-Sugar Wet Spots with 0.01% Fluorescein Sodium Salt

(30) The feasibility of using the fluorescein sodium salt based spray on products containing the PUF binder was studied:

(31) Small disc-shaped stone wool samples with three 25% or 45% PUF-sugar (PUF-binder with 25% and 45% dextrose) model wet spots were obtained in a similar manner to the one described in Example 1, in this case by drying the stone wool discs with added binder at 80 C. for 1 h instead of at 105 C. for 30 min.

(32) Solutions of 0.01% fluorescein sodium salt in 20% absolute ethanol in deionized water or in 20% isopropanol in cold tap water were sprayed onto the stone wool discs with model wet spots and investigated under 365 nm UV-light, 254 nm UV-light and daylight. Results identical to those obtained in Example 1 were obtained (FIG. 4-1 with 25% dextrose left and 45% dextrose right at 365 nm, FIG. 4-2 at 254 nm and FIG. 4-3 in daylight). 0.01% fluorescein sodium salt can also be used to detect PUF-based wet spots and no sensitivity towards the nature of the solvent was observed.

Example 5: Detection of Curing on Outer Surface of Stone Wool Products with B1-Sugar-Urea Using 0.01% Fluorescein Sodium Salt

(33) 0.01% fluorescein sodium salt in 20% aqueous ethanol was tested on the outer surface of an acoustical ceiling product with regions of uncured binder, the binder being the B1-sugar-urea binder (after removing the fleece layer from the acoustical ceiling product). The areas with uncured regions appear as discrete soft bumps on the surface. A product not containing uncured regions produced a regular curing oven pattern of bright green fluorescence on a apparently black background. The areas with uncured regions gave irregularities in this pattern (FIGS. 5-1 and 5-2).

(34) 0.01% fluorescein sodium salt in 20% aqueous ethanol was likewise tested on the outer surface of the areas with uncured regions of products with B1-sugar-urea binder. A product not containing uncured regions, as above, produced a regular curing oven pattern of bright green fluorescence on an apparently black background. Areas with uncured regions (some of them visible to the naked eye as soft bumps) gave irregularities in this pattern (Low density products: FIG. 5-3 before sprayingFIG. 5-4 and FIG. 5-5 after; high-density products: FIG. 5-6 before sprayingFIG. 5-7 and FIG. 5-8 after). The spray can also be used in daylight (without UV): The areas with uncured regions gave non-colored irregularities on a light green background (FIG. 5-9).

Example 6: Detection of Degree of Curing on Split Surfaces of Stone Wool Products with B1-Sugar-Urea Using 0.01% Fluorescein Sodium Salt

(35) The Rockwool products with B1-sugar binder used in example 5 were split open with a saw and inspected on the split surfaces using 0.01% fluorescein sodium salt in 20% aqueous ethanol. A hardly visible wet spot was identified in the layer directly below an area with uncured regions area on the curing oven surface (FIG. 5-10 before spraying). When sprayed, the areas not containing uncured regions will fluoresce brightly green while the wet spot will appear black (FIG. 5-11). The spray can also be used in daylight (without UV): The wet spot and saw trail appear dark brown while the background appears light green (FIG. 5-12).