CS212212B2 - Cement product reinforced by glass fibres - Google Patents

Description

It is also known to increase the effect of the protective materials mentioned above by incorporating them into coating compositions with partially cured phenol-formaldehyde resins of the water-soluble resol type in the A state, which are then further cured. It is believed that the protective material is likely to be enclosed by both a chemical and a physical means in the cured resin matrix from which it may be slowly released.

If the protective material, i.e. the hydroxy compound or compounds, is only dispersed in the carrier and then applied to the fiber, it is difficult to ensure that the material remains on or near the fiber surface during various operations performed during the production of the cementitious compound.

It is believed that in order to obtain a further increase in durability beyond that obtained simply by dispersing the protective material in the carrier, it is necessary to ensure that the carrier reacts chemically with the protective material or that the protective material is physically maintained near the fiber surface in such a way that it could release the effect of the environment on the coated surface of the fiber.

Accordingly, the present invention provides a cementitious composite material comprising coating the fibers by drying and curing with crosslinking in an aqueous mixture of three components, namely a film-forming material having a free water-soluble aliphatic-hydroxy group formed by the trihydroxy ester reaction or a dihydroxy-substituted aromatic carbonic acid with an alcohol having at least two hydroxyl groups per molecule, and a crosslinking agent, wherein the hydroxyl groups of the film-forming material are crosslinked such that the glass fiber coating is a thermoset and also retains the ester.

According to a preferred embodiment of the invention, the ester is also crosslinked to the film-forming material by at least one aliphatic-hydroxyl group in its molecule.

According to a further preferred embodiment of the invention, the cementitious matrix comprises reactive silica.

According to a further preferred embodiment of the invention, the reactive silica is in the form of fine silica flour or pozzolanic material.

According to another preferred embodiment of the invention, the cementitious matrix comprises 10 to 40% by weight of reactive silica.

By these measures according to the invention, it is achieved that the ester constituting the protective material substantially increases the glass fiber protection effect when incorporated into the cementitious composite material. It is unclear whether the effect is achieved by inhibiting or significantly reducing the effect on the glass fiber during the initial solidification of the cement by slowly releasing the protective material during this period, or whether the protective material actually releases for a long time. However, it is apparent that retention of the protective material, i.e. ester, in the coating composition resulted in better retention of the strength of the composite material and a reduction in strength or loss of strength to a great extent compared to the reduction in strength using alkali resistant fibers without any protective coating or even alkali resistant fibers having a protective material dispersed in a carrier and coated thereon.

Specific embodiments of the invention will now be described in detail by way of example.

Various criteria must be observed when forming the coating compositions to be suitable for coating all kinds of glass fibers, in particular the type known as continuous filaments. Probably the most stringent requirements are those for coatings that can be applied as a lubrication to continuous glass fibers when they are drawn from the drawing matrix. In this case, it is necessary to obtain a film on the surface of the glass fibers which will protect the glass from physical damage during further processing, i.e. when the threads are joined into a strand that is wound into a strand or as a strand or strand is metered into the mower. The film must also help to adhere the individual fibers together to form a strand or bundle of fibers.

The fibers are formed mechanically by drawing glass jets flowing out of the holes at the bottom of the platinum vessel known as the spout, the fibers having a very high temperature and the lubrication must be applied to the glass fibers when drawn from the spout.

In order to achieve safe and suitable working conditions, it is advisable to avoid systems that use organic solvents of any kind as liquid carriers.

The invention is based on the development of an aqueous lubrication that adheres to various criteria dictated by operational requirements for lubricating continuous shaped glass fibers and also provides, after drying and heat treatment, a coating on fibers containing a material capable of increasing the durability of glass fibers in alkaline environments such as inorganic cement base mass.

The aqueous lubrication consists essentially of at least one water-soluble film-forming material having free hydroxyl groups, at least one water-soluble ester formed by reacting a trihydroxy-substituted or dihydroxy-substituted aromatic carboxylic acid with an alcohol having at least two hydroxyl groups, and a crosslinker a composition capable of crosslinking the hydroxyl groups of the film-forming material to cure it, and possibly also crosslinking the ester into the film-forming material.

Suitable water-soluble film-forming materials with free hydroxyl groups include materials formed by the reaction of epoxy resins with a secondary amine to remove either all or part of the epoxy groups present in the resin as needed to create solubility in water or in dilute organic acids, e.g. acetic. .

Epoxy resins are usually obtained by reacting bisphenol A with epichlorohydrin. By using different proportions of these materials with different amounts of alkali catalyst, it is possible to obtain polymers of different molecular weights. Suitable secondary amines include diethanolamine, morpholine, piperidine and pyrrole. Resins can also be prepared by reacting epichlorohydrin directly with a secondary amine, such as di-n-butylamine, and then reacting the product with a primary hydroxyamine, such as ethanolamine.

The formation of the solubility of epoxy resins is described in British Patent Nos. 1,129,005, 1,103,325 and 1,037,292. The materials described in these patents and produced by the reaction of an epoxy resin with an amine are suitable for use as the film-forming material of the invention . It is preferred to use a material formed by the reaction of epoxy compounds of the type described in the above patents and secondary amines, the reaction being carried out to ensure that the reaction is substantially complete and that no epoxy groups can be detected by standard analytical methods. progresses. Other film forming materials include polyhydric alcohols such as polyvinyl alcohols or partially hydrolyzed polyvinyl acetates.

In preferred embodiments of the invention, the hydroxy-substituted carbonic acid ester contains at least one free, i.e. unreacted, hydroxyl group in addition to the esterified group, thereby promoting the solubility of the ester in water. It is believed that the free hydroxyl group is also capable of reacting with the crosslinking agent, thereby binding the ester to the water-soluble film forming material and thereby increasing ester retention in the coating. The cross-linking agent is further selected to also act to cross-link the film-forming material with the hydroxyl groups in the film-forming material to form a partially or fully cured three-dimensional film with thermosetting properties.

Suitable acids are aromatic trihydroxycarboxylic acids, for example gallic acid and various dihydroxybenzoic acids.

As esterification alcohols, at least a dihydric alcohol and preferably a polyhydric alcohol are used in order to preferably form the ester with a free hydroxyl group and to allow reaction with the crosslinking agent. Typical esterification alcohols are alcohols having a molecular weight of at least 62, i.e. ethylene glycol or various polyethylene glycols, but it is advisable to avoid the use of relatively high molecular weight alcohols as the relative proportion of active crosslinking sites changes with increasing molecular weight. It is preferred to use polyethylene glycols with a molecular weight below 600. Other compounds such as pentaerythritol, sugars, starches, celluloses and polyvinyl alcohols may also be used.

In some cases, the film-forming material may be an alcohol which is esterified with an aromatic carbonic acid, so that the two components are combined. For example, this may be the case when the film-forming material is polyvinyl alcohol, which is esterified with trihydroxy or dihydroxy-substituted aromatic carbonic acid, for example gallic acid, to form a water-soluble ester.

With respect to the crosslinker, it is preferred to use an aminoplast, i.e. a material having one or more melamine rings substituted with either a methyl or esterified methylol group on the melamine ring or rings. In the case of esterified methylol groups, the reaction rate increases with the volatility of the alcohol used, so that the methanol esters will react faster than the n-butanol esters.

Since rapid curing is required in most cases, it is preferable to use methanol derivatives, and among the available commercially available materials is, for example, a structural formula:

Ih ₃ COOH ₂ OCH ₃

Another suitable crosslinker has a similar structure, but some of the amino groups in the molecule are unsubstituted and the proportion of methylol groups is not esterified, and thus the crosslinker is probably more reactive. It has been found that this difference in reactivity has no meaning for the purposes of the invention and that these compounds are interchangeable in the compositions of the invention.

It is understood that chemical reactions that take place to form a resin with thermoset properties and to chemically react the ester into the resin system may be illustrated by the following schemes in which the aminoplast crosslinker is represented by the formula MCCH 8 OCH 2.

When the hydroxy-substituted carboxylic acid is gallic acid, ester formation can be expressed as

HIM

wherein R is an alkyl chain, wherein the number of carbon atoms in the chain is any number from 2 to the upper limit, depending on the degree of polymerization. Possible reactions between gallic acid ester and aminoplast are

HIM

HIM

HO _ ^ A_C_ ₀ - (R) -CH ₂ + O] -N (CH ₂ OCH _{3) N}

OH |

HO <

-λν

HOCH ₂ -M (CH ₂ OCH ₃ ) _n .

HIM

STEED

CH ₉ µl

It is believed that treatment with an alkaline environment either induces the release of the ester from the film and then, after saponification, induces the liberation of the acid or liberates the free acid directly. By virtue of any theory, which is true, it will not be understood that retention of the ester of the coating upon crosslinking of the film-forming material will increase the overall effect of the ester on durability, probably by controlling or limiting its release into the aqueous cementitious matrix.

*

It has been found that using the same glass composition, the strength is first increased by simply applying the free acid to the fiber and further increased by using the same acid as the fiber applied to the fiber and even further by retaining the ester in the coating according to the process.

For application to continuous glass fibers, in addition to the essential ingredients described above, the lubricating composition may contain, if desired, other substances to form a suitable lubricant.

Other normally present components in the lubricant composition include silanes that help bind the film-forming material to the glass surface, and lubricating lubricants to lubricate the glass surface. British Patent Specification No. 1,057,292 at page 1 in line 23 to page 2 of line 20 discloses stringent conditions that lubricants of this kind must withstand, and it is clear that various additives are possible to prepare a suitable lubricant.

It has been found that there is no difficulty in designing the composition of a lubricating composition that can be put into operation to produce continuous fibers under safe conditions from a spout, using film forming materials, esters and crosslinking agents as described above. No attempt has been made to investigate the various permutations and combinations of other components that may be added.

The following specific examples illustrate the invention. Unless otherwise indicated, all percentages in the examples are by weight.

Example 1

In order to show that the improvement produced by the coating of the glass fibers according to the invention is due to the use of a combination of film-forming material, ester and crosslinking agent and not obtained with only one or two components, a series of comparative tests were performed as described below.

Eight lubricants were prepared based on the following general formula;

% film-forming resin 5 ester 10 silanes (as coupling agent) 0,5 quaternary ammonium chloride (as cationic surfactant) 0,5 crosslinking agent 2,0 acetic acid to adjust pH to 4 to 4,5

VOBa to be added up to 100%

Lubrication I (no ester ahi enhancer)

It was a known type of lubricant composition, with the ester and crosslinking agent omitted from the above prescription. The film-forming resin was formed by reacting the bisphenol A diglycidyl ether with ethanolamine to make it water-soluble.

Lubrication II (no enhancer)

The film-forming resin in this case was the same as for the lubrication I. The ester was ethylene glycol ester of gallic acid. Again, no crosslinking agent was incorporated.

The ester was made by mixing 1 mole of ethylene glycol and 0.5 mole of gallic acid, followed by a catalytic amount (0.008 mole) of toluene-4-sulfonic acid. The mixture was then slowly heated to 1 60 ° C and the reaction water was removed using a Dean and Stark trap. Heating was continued until the esterification was to the point where the product had a free acid content of 5 to 8% · The molar ratio of acid to alcohol was chosen so that the monosubstituted ester could primarily be formed.

Lubrication III (no ester)

This was the same as I, but in this case a crosslinking agent was added. It was an aminoplast according to the above structural formula.

Lubrication IV

This lubrication was the same as lubrication III, except that the same ester as incorporated in lubrication II was used again in this recipe. Thus, Lubrication IV agreed to carry out the invention.

Lubrication V (no ester)

This lubrication was the same as lubrication III, with the advantage that the crosslinker was an aminoplast according to the above formula, but with some unsubstituted amino groups.

Lubrication VI

This lubrication differed from V only in that the same ester was used as in Lubricants II and IV. Thus, lubrication VI was like lubrication IV, except for the use of a different crosslinking agent, and was in accordance with the invention.

Lubrication VII

This lubrication was the same as VI, except that the ester used was gallic acid glycerol ester, made by mixing 1 mole of glycerol and 3 moles of gallic acid. The preparation was carried out according to the same procedure as described for the ethylene glycol ester of gallic acid in lubrication II.

Lubrication VIII

This lubrication was the same as that of VI, except that the ester used was polyethylene glycol ester of gallic acid produced using polyethylene glycol. The ester had a molecular weight of 300 and the molar ratio of acid to alcohol was 1: 1. The ester preparation was carried out differently as described for Lubrication II.

Each lubrication was used to coat strands of fibers of essentially alkali resistant glass containing zirconia and having the following molar composition:

silicon dioxide SiO ₂ 69% zirconia ZrO ₂ 9% sodium oxide Na ₂ O 15,5% calcium oxide CaO 6,5%

The deposition of the lubrication on the springs was of the order of 2%. The differently coated strands were then dried at 130 ° C, thereby crosslinking in the film-forming material and between the ester and the film-forming material where a cross-linking agent was present. The middle portion of each coated strand was then sealed into a block of plain Portland cement in a pasty state, which was then allowed to cure for one day at 100% relative humidity and then held for 28 days in water at 50 ° C to produce the accelerated aging effect. The tensile strength of the strand immediately after luhrification and the tensile strength of the closed portion after storage were measured. The results of these strength measurements in MPa are shown in Table 1.

Due to the differences in the composition of the lubrication and the resulting different degree of mechanical damage induced during the preparation of the test strands, it is difficult to achieve the same baseline value for comparison purposes. In this test, it is tested that the final immersion value at 50 ° C is largely unaffected by the initial baseline. It is always important to rely on relative performance in a particular series of tests, rather than comparing the absolute values of one test to another.

Table I Tensile Strength (MPa) beginning after 28 days of immersion at 50 ° C

Lubrication AND 1 450 597 Lubrication II 1 400 655 Lubrication III 1 381 556 Lubrication IV 1 480 926 Lubrication in 1 546 474 Lubrication VI 1 540 785 Lubrication VII 1 474 867 Lubrication VIII 1 341 906

β

Obviously, the final values in the case of lubricants I, III and V which do not reach any ester in the formula are of the same order. The addition of the ester gives in all cases improved final values, as can be seen with lubricants II, IV, VII and VIII.

In the case of lubricants IV, VI, VII and VIII, the action of the crosslinking agent produced a further improvement with respect to the lubricants II. It is evident from a direct comparison by lubrication that differs only by the presence of the ester that the improvement is due to the ester, i.e. by comparing I with II, III with IV and V with VI.

Example 2

Tests were carried out in the same manner as in Example 1 to detect the effects of different film-forming resin and different amounts of lubrication retained on the fiber strands. For some sizing, such a curing or drying region has been found in terms of temperatures. Following lubrication were:

Lubrication IX

Resin as in lubrication I 5 ethylene glycol ester of gallic acid as in lubrication II 10 silane as coupling agent 0,5 cationic surfactant 0,5 crosslinking agent 2,0 acetic acid 2,0 water up to 100%

Lubrication X

This was the same as IX, except that the resin used was a reaction product of propylene glycol diglycidyl ether and ethanolamine, and the two compounds reacted to obtain a water-soluble resin.

Lubrication IV - is described in Example 1. The results obtained are as follows

Lubrication EXCESS NO. capture drying temperature (curing) tensile strength (MPa) beginning after 28 days at 50 ° C after 56 days at 50 ° C 1 3 120 1 070 889 2 1.5 130 1 071 866 1 0.8 130 904 647 2 0.8 drying the RF 760 588 3 0.8 drying the RF 827 556 4 - 2,0 130 1 071 866 742 1 2,0 120 1 141 747 2 1,8 160 1 171 628 3 2,0 130 1 000 808 4 3.3 120 1 193 731 5 9.3 120 1 345 927 6 1’P 120 1 571 873 7 1.9 105 1 071 682 8 2.2 130 1 156 864 9 1.4 190 932 589

The VK drying data indicates that the lubrication was dried and cured by high frequency heating, with an effective temperature of at least 120 ° C. Obviously, maintaining water strength at 50 ° C was affected by the amount of lubrication deposition. By continuously drawing the glass fibers, it is difficult to exceed the deposit of 3% with these lubricants. In order to achieve higher values using Lubrication IV, Tests 5 and 6, overlapping technology had to be used.

It is also evident that the strengths measured after 28 days at 50 ° C are of the same order as the strengths obtained after 28 days in Example 1 as opposed to the variations in the initial strengths.

Example 3

Glass fiber reinforced cement composite boards were produced by a spraying and dewatering process in which cement and chopped glass fibers were sprayed into a mold and this mass was dewatered by hay. The binder used was as follows:

Portland cement quick setting 30 sand 10 water 15

The final water to cement ratio in the finished slab was set to 0.3 and the glass content was 5%.

(based on dry glass weight \ fraction: -----------------.. ......- .........- 1 weight of solids t water /

The glass fibers used had the compositions described above and were lubricated by the X lubrication of Example 2. Each plate was cut into 150 x 50 mm and 8 mm thick sections and cured for 1 day at 100% relative humidity and then 6 days ve. water at 120 ° C. They were then stored in water at 150 ° C and tested at various intervals up to 3 months. The flexural strength (PO) and the impact strength (RH) were then measured (PO in MPa, RH in N.mm / mm).

Obviously, in accelerated testing over a comparatively long period of service corresponding to many years of service, the fiber-containing boards coated according to the invention showed a significant increase in both flexural strength and impact strength over control samples.

exam who. 1 4 days 28 days 56 days 3 months lubrik. X 1-PO 33.3 32.6 30.4 23.9 RH 28.3 15.4 12.7 9) 9 2-PO 36.4 32.5 28.8 23.0 19.1 RH 22.0 14.8 10.8 7.7 6.0 PO inspection 38.1 19.4 16.8 15.4 13.6 lubrik. I SH 28.5 5.6 3.3 2,0 2,0

Example 4

Glass fiber reinforced cement composite boards were produced by a spraying and dewatering method in which cement and chopped strands of fibers were sprayed into the mold and dewatered by suction, the cement used was supersulphated cement. The binder used was as follows:

13.5

Super sulphate cement water

The final water / cement ratio in the final plate was 0.26 and the glass content was 5% (based on the ratio of dry glass to solids and water). The glass strands used were of the above composition and were lubricated by the lubrication X of Example 2. Each plate was cut into 150 x 50 mm portions of 8 mm thickness and the portions were cured for one day at 100% relative humidity and then 28 days in water at 22 ° C. They were then stored in water at 50 ° C and tested at various intervals up to 3 months;

O

The flexural strength and impact strength were then measured (PO in MPa, RH in N.mm / mm).

Exam beginning 14 days 28 days 56 days 3 months Control (no protective) materiél) AFTER 26.7 26.1 24.6 19.7 19.7 RH 20.4 12.3 7.6 6.3 4.3 Lubrication X AFTER 36.1 39.7 41.3 42.0 42.2 RH 21, 4 22.1 7.3 19.4 18.4

Thus, an improvement was again noted in the glass fiber boards coated according to the invention.

Example 5

As mentioned above, a further improvement in the durability of glass cloths in cement has been found where the cement contains reactive silica in the form of a pozzolanic material. This example illustrates the effect of using a proportion of fine flour silica (Danish diatomite containing 81.5% silica of particle size such that 50% of the portion is less than 30 microns and none is greater than 200 microns as determined by the Coulter counting method), with the same rapid curing potland cement as used in Example 3.

The sliver strands were made of alkali-resistant glass of the above composition, some of which were coated with standard polyvinyl acetate lubrication and some of the X lubrication described in Example 2. The middle portions of the strands were incorporated into cement paste blocks. For each type of coated strand, some blocks were 100% fast setting Portland cement and some 80% fast setting Portland cement and 20% Danish diatomite. The blocks were kept in water at 50 ° C for 2 months to produce accelerated aging and the strands were then tested for tensile strength.

The following results were obtained in MPa. The percentages in brackets indicate an improvement over polyvinyl acetate-lubricated fibers in 100% Portland cement.

Portland Cement Quick-setting 100% Portland Cement Quick-setting 80% Danish diatomite Lubricated fiber polyvinyl acetate 460 640 (39.1%) Lubricated fiber lubrication X 570 (23.9%) 919 (100%)

Therefore, the improvement made using the use of a lubricant X in cement containing 20% silica meal is greater than the sum of the improvements found when using a lubricant X in 100% Portland cement or using 20% silica meal in cement on conventional lubricated glass slags, a synergistic effect between the lubricating composition of the invention and the silica flour.

Example 6

Further investigations in the same line as in Example 5 were carried out using the same fast-hardening Portland cement with different amounts of pozzolanic or fly ash and a Danish diatomite silica meal as described above and a silica meal consisting of 96.7% oxide. Silica having a particle size such that 50% of the particles are less than 30 microns and none are greater than 110 microns as determined by the Coulter counting method. The strands of the same glass fibers as before were lubricated for comparison with three different lubrications, namely the conventional polyvinyl acetate lubrication followed by the lubrication described in British Patent Specification No. 1,465,059 and containing pyrogallol as a dispersant in the carrier, and finally the lubrication X described above,

The tensile strength of the strands was measured after various times and with the following results:

Basic material liner lubr. tensile strength MPa time in water at 50 ° C months 0 1 2 100% fast polyvinylaoetét 1 200 530 460 hardening portlandský pyrogallol 1 120 670 560 cement lubrikace X 1 190 750 570 60% fast polyvinyl acetate 1 290 670 530 hardening portlandský pyrogallol 1 210 840 780 cement 40% downy ash lubrikace X 1 350 980 840 90% fast setting Portland cement 10% Danish diatomite lubrikace X 1 220 1 070 720 80% fast hardening portlandský polyvinyl acetate 1 120 790 640 cement 20% Danish diatomite lubrikace X 1 230 1 080 92B 60% fishy hardening porltandský polyvinyl acetate 1 140 1 060 830 cement 40% Danish diatomite lubrikace X 1 180 1 240 1 030 90% fast setting Portland cement 10% meal oxide silica lubrikace X 1 420 920 730 80% fast durable portlandský polyvinyl acetate 1 160 720 560 cement 20% meal oxide silica lubrikace X 1 420 1 010 850

Base material coating, lubricant. tensile strength MPA time in water at 50 ° C months% fast setting Portland cement% silica flour

0 1 980 2 940 polyvinyl acetate 1 080 lubrikace X 1 330 1 260 1 230

These results confirm a further increase in durability achieved by using the lubricant composition of the invention for cement containing 10 to 40% reactive silica

Claims (5)

Cement product reinforced with glass fibers, the cementitious material of which forms an alkaline environment on the surface of the glass fibers embedded in the cementitious product, and a protective coating is formed on the glass fibers against attack by said alkaline environment, characterized in that the protective coating comprises an ester having or a dihydroxy-substituted aromatic carbonic acid by hydrolysis on the surface of the glass fibers in contact with said alkaline environment and a thin-film crosslinked film-forming material reacted with the ester so as to retain the ester and the acid adjacent the surface of the glass fibers. Cement product according to claim 1, characterized in that the ester is also crosslinked with the film-forming material. Cement product according to claim 1 or 2, characterized in that the cementitious material comprises reactive silica. Cement product according to claim 3, characterized in that the reactive silica is in the form of a fine silica flour or a pozzolanic material. Cement product according to claim 3 or 4, characterized in that the reactive silica is present in the cementitious material in a concentration by weight of 10 to 40%.