FI68800C - CEMENTSAMMANSAETTNING INNEHAOLLANDE GLASFIBRER SAOSOM FOERSTAERKNINGSMATERIAL - Google Patents

Description

68800

Cement composition containing glass fibers as a reinforcing material

The invention relates to a cement composition containing glass fibers as a reinforcing material, wherein the glass fibers are coated with a composition containing a film-forming material intended to protect the glass fibers from degradation in an alkaline environment of a cement matrix.

10 The use of glass fibers as a cement reinforcement has become possible with the development of alkali-resistant glass fibers made from, for example, the glass compositions described in GB Patent 1,290,528, sold under the tradename "Cem-FIL" by Fiber-15 glass Limited. Depending on the glass composition, the durability of the base-resistant glass fibers may vary. The corrosive effect on the environment may also vary. For example, in dry conditions, durability is better than when glass-fiber-reinforced cement compositions are exposed to the outside weather. Sometimes it may be necessary to achieve better durability than that achievable by changes in glass composition or to improve the durability of glass without increasing the cost of the components of the charge. GB-A-1 465 059 describes coating compositions which can be used to protect glass fibers to reduce the degradation of glass fibers added to cement products when the preservative is formed from at least one monocyclic or polycyclic renomatic aromatic compound having at least three hydroxyl groups in at least one aromatic ring. It has been found that such preservatives improve the durability of glass fibers in an inorganic cement matrix. GB Patent 1,524,232 also describes coating compositions containing at least one dihydroxybenzoic acid as a preservative which has been found to improve the durability of glass fibers in an inorganic cement matrix. GB 1,519,041 describes a method for improving the effectiveness of the preservatives 5 described in the above-mentioned patent applications by incorporating them into a coating composition with a water-dilutable resolution-type, partially cured A-phase phenol-formaldehyde plastic which is then cured. This is believed to encapsulate the preservative, probably both chemically and physically, in the cured plastic matrix from which it is slowly released.

If the preservative, i.e. the hydroxy compound or compounds, only dispersed in the carrier and then coated with the fiber, have been found to be difficult to retain the substance on or near the surface of the fiber during the various stages of preparation of the cement composition. It is believed that to achieve durability that is better than simply dispersing the preservative in the carrier, it is necessary to chemically react the carrier with the preservative or physically keep the preservative in the vicinity of the fibrous surface so that the environmental effect on the coated fiber surface releases the preservative. .

The cement composition according to the invention is characterized in that the composition used for coating glass fibers also contains a water-soluble ester prepared by reacting a trihydroxy- or dihydroxy-substituted aromatic carboxylic acid with an alcohol having at least two hydroxyl groups. via hydroxyl groups so that a thermosetting film coating is formed on the glass fibers which also retains the ester.

The reaction to form the ester is preferably carried out so that the ester molecule has at least one 68,800 free (i.e., unreacted) aliphatic hydroxyl group because it promotes the dissolution of the ester in water. It is likely that in the drying and curing step, the crosslinking agent will generally also crosslink the aliphatic hydroxyl group or groups of the ester to the hydroxyl groups of the film-forming agent.

The ester has been found to significantly improve the protection of glass fibers in cement compositions. It is not clear whether this inhibition or significant reduction in corrosion of the glass fiber is due to the slow release of the preservative in the early stages of cement curing or its release over a relatively long period of time. However, it will be appreciated that the inclusion of a preservative (ester) in the coating composition 15 in accordance with the invention can better preserve the strength of the composition and significantly reduce the rate of strength degradation compared to the base-resistant fiber currently used without the coating or even the base-resistant fiber.

GB Patents 1,129,005, 1,103,325 and 1,057,292 describe compounds suitable for use as a film-forming agent.

Preferably, the film-forming agent is a product prepared by reacting an epoxy compound with a secondary amine to remove all of the original epoxy groups, although in some cases it may be advantageous to remove only a portion of the original epoxy groups that dissolve in water or dilute organic acids. e.g. acetic acid. In either case, the epoxide compound is preferably a product prepared by reacting bisphenol A with epichlorohydrin. The secondary amine may be diethanolamine, morpho-35, piperidine or pyrrole.

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Alternatively, the film-forming agent may be a product prepared by reacting an epichlorohydrin with a secondary amine and then reacting the product with a primary hydroxyamine such as ethanolamine.

Preferably, the ester is a gallic acid ester, although it may also be a dihydroxybenzoic acid ester. The esterification alcohol may be ethylene glycol, glycerol or polyethylene glycol having a molecular weight of less than 10,600.

The crosslinking agent is preferably an amino resin having one or more melamine rings and methylol and / or esterified methylol groups as substituents. Preferably, the esterified methylol groups are esterified with methanol-15a.

U.S. Patent No. 3,948,673 describes the use of water-soluble polymers in an adhesive for coating glass fibers to improve the processability and filamentability of the glass fibers. When these adhesive-coated glass fibers are added to an aqueous inorganic medium (e.g., a cement slurry), the polymer dissolves and therefore the polymer is no longer present on the surface of the glass fiber filaments in the final cured cement matrix. In contrast, according to the present invention, the thermosetting film coating remains on the surface of the glass fibers even when the glass fibers are added to the cement composition, i.e. in the final cement product.

SE Patent Publication No. 223175 discloses an adhesive composition for glass fibers comprising a water-soluble film-forming material and a water-soluble ester. However, the film-forming material and the water-soluble ester are different in nature from the composition of the present invention. These 5,688,800 do not contain hydroxyl groups in their molecule that could cause substantial crosslinking of the present composition. Ko. Furthermore, the SE publication is intended to eliminate the tacky nature of the composition 5 in order to facilitate the subsequent handling of the coated fibers.

The coating composition described above is preferably applied to the continuous glass filaments by drawing them from the molten glass through a plurality of holes or tips in the bottom 10 of the nozzles. The filaments are combined into bouquets or strands and immediately wound on a frame into a cake. The cakes are dried and a curing reaction takes place at the same time. Preferably the drying (and curing) is carried out at a temperature of at least 120 ° C, in particular 130 ° C, preferably for 6-12 hours. The exact choice of circumstances depends on the size of the cake.

The coating composition preferably also contains a silane which promotes the adhesion of the film-forming material to the surface of the glass, and may also contain a lubricating adhesive to reduce friction between the coated surfaces of adjacent filaments.

It is known to improve the retention of the strength of alkali-resistant glass fibers in an inorganic cement matrix by adding reactive silica in the form of potso-25. For example, British Patent 1,402,555 describes the use of Italian pozzolan in the form of ground fly ash (PFA). It has now been found that when reactive silica is added to the cement with the coated fiber described above, the strength is better preserved than is expected by combining the improvements alone.

It has been found that cement can generally be replaced by up to 40% active silica. The lower limit likely to be useful is about 35 10%, but both the upper and lower limits depend to some extent on the nature of the substance used. The upper limit is proportional to the water requirement of the active silica used and the strength of the matrix, and the lower limit to its reactivity.

The following examples illustrate the invention:

Example 1

Glass fiber reinforced cement sheets were prepared using a spray-dewatering method in which cement and fiberglass staple fibers were sprayed into a mold and water was removed by suction. The cement used was:

Ferrocrete, fast setting portland cement 30

Sand 10 15 Water 15

The final water to cement ratio of the finished sheet was adjusted to 0.3 and the glass content was 5% (weight of dry glass by weight of solids and water).

20 Fiber strands made of almost alkali-resistant, zirconium-containing glass were used as the glass fiber. The composition of the glass in mole% was:

SiO2 69

ZrO 2 9 25 Na 2 O 15.5

CaO 6.5

The fibers were glued with an adhesive having the following composition:

Weight-%

Film-forming plastic (reaction product of propylene glycol diglycidyl ether and ethanolamine) 5

Gallic acid ethylene glycol ester 10 35 "Silane A187" crosslinker (V'-glycidoxypropyltriethoxyethoxysilane, manufactured by Union Carbide) 0.5 7 68800 "Arquard 12/50" cationic wetting agent (alkyl quaternary ammonium chloride, manufactured by Union Carbide)

Armor Hess) 0.5 "Cymel 300" crosslinker 5 (melamine with all amino groups substituted with methyl esterified methylol groups, manufactured by Cyanamide on Great Britain Limited) 2.0

Acetic acid to adjust the pH to 4-4.5 2.0 10 Water to 100%.

Each cement board was cut into pieces of 150 x 50 x 8 mm and the pieces were cured for one day at 100% relative humidity and six days in water at 22 ° C. They were then stored in water at 50 ° C and the precipitate was tested periodically for three months. The modulus of fracture (MM) and the impact strength (IK) were determined as follows (MM as N / mmz and IK as Nnun / mm).

Driving Departure 14 days 28 days 56 days 3 months 20 _ ^ 2_

Test adhesive 1- MM 33.3 32.6 30.4 23.9 IK 28.3 15.4 12.7 9.9 2- m 36.4 32.5 28.8 23.0 19.1 IK 22, 0 14.8 10.8 7.7 6.0 25 Reference adhesive m 38.1 19.4 16.8 15.4 13.6 IK 28.5 5.6 3.3 2.0 2.0

The composition of the reference adhesive was otherwise similar to that of the 30 test adhesives, except that the ester and crosslinker were omitted and the reaction product of bisphenol A diglycyl ether and ethanolamine was used as the film-forming plastic.

It can be seen from the table that in the accelerated test 35, for a relatively long period of time corresponding to many years of use, both the fracture modulus and the impact resistance of the boards containing the fibers coated according to the invention were clearly better than in the control group.

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Example 2

Glass fiber reinforced cement sheets were prepared using a spray-dewatering method in which cement and fiberglass staple fibers were sprayed into a mold 5 and water was removed by suction. The cement used was: Supersulphated cement 30

Water 13.5

The final water to cement ratio of the finished sheet was 0.26 and the glass content was 5% (10 wt.% Of dry glass by weight of solids and water). As the glass fiber, a fiber of the composition described above glued with the glue of Example 1 was used. Each plate was cut into pieces of 150 x 50 x 3 mm and the pieces were cured for one day at 15% relative humidity and 28 days in water at 22 ° C. They were then stored in water at 50 ° C and tested periodically for up to three months. The fracture modulus (MM) and impact resistance (IK) were determined as follows (MM as N / mm 2 and IK as Nmm / mm).

20

Driving Departure 14 days 28 days 56 days 3 months _value___________

For comparison Lna KK 26f 7 21.1 24.6 19.7 19.7 25 (no preservative) IK 20.4 12.3 7.6 6.3 4.3

Test adhesive KK 36.1 39.7 41.3 42.0 42.2 IK 21.4 22.1 17.3 19.4 18.4 Again, a clear improvement can be observed in sheets containing glass fibers coated according to the invention.

Example 3

As mentioned above, it has been found that the durability of the glass fibers in the cement is further improved by incorporating reactive silica in the form of pot-solane into the cement. This example demonstrates the effect of using partially finely divided silica powder (Danish diatomaceous earth Damolin, which contains 81.5% by weight of silica, 50% of the 9,6800 particles of which are smaller than 30 μm and the largest size of 200 yarns determined by the Coulter Counter method ), as well as the same fast-setting Portland cement (Fer-rocrete) as in Example 1. Base-resistant fiberglass filaments were prepared from the above composition, some of which were coated with a standard polyvinyl acetate adhesive (PVA) and some with the adhesive described in Example 1. The middle portions of the strands were added to the cement mortar cubes. For each type of coated fiber, either 10 cubes containing 100% Ferrocrete Portland cement or cubes containing 80% Ferrocrete Portland cement and 20% Danish diatomaceous earth were used. The cubes were kept for two months in water at 50 ° C to accelerate aging and the tensile strength of the strands was determined. The results (N / mm) are shown below. Percentages in parentheses indicate superiority over PVA-bonded fiber filament in 100% Portland cement.

100% Ferro- 80% Perro- cretea cretea + 20% Danish diatomaceous earth PVA-glued fiber 460 640 (39.1%)

Fiber glued with test glue 570 (23.9%) 920 (100%) 25

The improvement obtained by using the adhesive of Example 1 in a cement containing 20% silica powder is thus greater than the sum of the improvements obtained by using the adhesive of Example 1 in 100% Portland cement or by using 20% silica powder in a cement with conventionally glued fiber, the reinforcing effect between the adhesive composition according to

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Example 4

Further studies were performed in the area treated in Example 5 using the same Ferrocrete-Portland cement and varying amounts of ground pozzolanic-5 ash (PFA), silica powder in the form of Danish diatomaceous earth (Damolin described above) and silica powder under the trade name Elkem containing 96.7% by weight silica. , of which 50% of the particles are smaller than 30 μm and a maximum size of 110 μm as determined by the Coulter Counter-10 method. The same fiberglass filaments were used as above glued with three different adhesives for comparison, namely 1) a conventional PVA adhesive, 2) an adhesive described in British Patent Specification 1,465,059 15 containing pyrogallol dispersed in a carrier as a preservative, and 3) an adhesive according to Example 1. The tensile strength of the filaments was determined at regular intervals and the results were: 20 Matrix Adhesive. , 7,,.

^. Gains tensile strength in cement

coating 5 J

(N / nxn)

Time in water at 50 ° C (months) __O_1_2_ 100% Ferrocrete- PVA 1200 530 460 25 cement Pyrogal- 1120 670 560 loli

Test adhesive 1190 750 570 60% Ferrocretea PVA 1290 670 530 40% Pozolane-Pyrogal 1210 840 780 PFA loli 30 Test adhesive 1350 980 840 90% Ferrocretea 10% Danish Test adhesive 1220 1070 720 diatomaceous earth 80% Ferrocretea PVA 1120 790 640 20% Danish Test glue 1230 1080 920 diatomaceous earth 68800 11 (Continued)

Matrix Adhesive- Thread in Cement Tensile Strength Main Adhesive {N / lnn2)

Time in water at 50 ° C (months) 5 _0_1_2_ 60% Ferrocretea PVA 1140 1060 830 40% Danish Test adhesive 1180 1240 1030 or diatomaceous earth 90% Ferrocretea Test adhesive 1420 920 730 2Q 10 S Elkem silica 80% Ferrocretea PVA 1160 720 560 20% Elkem Silicon Test Adhesive 1420 1010 850 Oxide 60% Ferrocretea PVA 1080 980 940 15 40% Elkem Silicon Test Adhesive 1330 1260 1230 Oxide These results show further improvement in durability when using the adhesive composition of the invention and 10-40% reactive silica. it-20 ment.

Claims (12)

A cement composition comprising glass fibers as a reinforcing agent, wherein the glass fibers are coated with a composition comprising a film-forming material intended to protect the glass fibers from degradation in an alkaline environment of a cement matrix, characterized in that the glass fiber coating composition also contains a water-soluble ester. is prepared by reacting a trihydroxy- or dihydroxy-substituted aromatic carboxylic acid with an alcohol having at least two hydroxyl groups in its molecule, wherein the film-forming material is crosslinked via hydroxyl groups in the molecule, so that a thermally curable film end is formed on the glass fibers. Cement composition according to Claim 1, characterized in that the ester is also crosslinked via the aliphatic hydroxyl group with the film-forming material. Cement composition according to Claim 1 or 2, characterized in that the film-forming agent is a product prepared by reacting an epoxide compound with a secondary amine so that all the original epoxy groups are removed. Cement composition according to Claim 1 or 2, characterized in that the film-forming agent is a product prepared by reacting an epoxy compound with a secondary amine so as to remove such a proportion of the original epoxy groups that the product is soluble in water or dilute organic compounds. acids such as acetic acid. Cement composition according to Claim 3 or 4, characterized in that the epoxide compound 68800 13 is a reaction product of bisphenol Δ and epichlorohydrin. Cement composition according to Claim 3, 4 or 5, characterized in that the secondary amine is diethanolamine, morpholine, piperidine 5 or pyrrole. 6 8 8 0 0 i ?. Cement composition according to Claim 1 or 2, characterized in that the film-forming agent is a reaction product of epichlorohydrin and a secondary amine, which is then reacted with a primary hydroxyamine, such as ethanolamine. Cement composition according to Claim 1 or 2, characterized in that the film-forming agent is a reaction product of diglycidyl ether of bisphenol A and ethanolamine, whereby a water-soluble resin is formed. Cement composition according to Claim 1 or 2, characterized in that the film-forming agent is a reaction product of propylene glycol diglycidyl ether and ethanolamine, whereby a water-soluble resin is formed. Cement composition according to one of the preceding claims, characterized in that the ester is a gallic acid ester. Cement composition according to one of Claims 1 to 9, characterized in that the ester is an ester of dihydroxybenzoic acid. Cement composition according to Claim 10 or 11, characterized in that the esterification alcohol is ethylene glycol, glycerol or polyethylene glycol having a molecular weight of less than 600. 14 68800