DE2413965A1 - PROCEDURE FOR REPAIRING CRACKS IN GLASS OBJECTS - Google Patents

Description

MINNESOTA MINING AND MANUFACTURING COMPANY Saint Paul, Minnesota, V.St.A.

"Procedure for Repairing Cracks in Glass Objects" Priority: March 22, 1973, Great Britain, No. 13 958/73

The invention relates to a method for repairing jumps in glass objects, in particular glass panes. The invention also relates to masses used in carrying out these repairs be attached.

Glass windows and the like develop under shock and tensile loads often jumps. For example, this occurs when there is swelling on wooden frames or when there are signs of corrosion Metal frame on. The only way to repair this damage previously consisted of replacing the entire pane of glass. However, this type of repair is time consuming and costly. It also requires a certain skill, as the damaged disc is removed and replaced with a new disc with the correct one Tearing out must be replaced. This is generally done with putty or other fillers are used as a sealing material. This J

409840/0831

Seals are then, if necessary, with a coat of paint Mistake.

The object of the invention is to provide a method for repairing To provide cracks in glass objects where 'the glass objects can stay in place. The repaired Objects should have sufficient strength at the cracks.

In the method according to the invention for repairing cracks in glass objects, in particular glass panes, liquid, Mixtures containing at least two copolymerizable monomers are used which wet glass in cracks from upright Penetrate glass and fill it in faster than it runs down the vertical glass that is before entry a noticeable polymerization have a viscosity of at most 1000 Cp, which are free of volatile, non-copolymerizable Solvents are and those without substantial expansion or contraction, without development of gaseous products and without external heat exposure at normal temperatures in the presence of a

or under the action of active radiation hardener / polymerize to a transparent mass, which. the

binds both opposing surfaces of cracks in the glass with sufficient strength to prevent the enlargement of a normal crack in a pane of glass when a normal cleaning force is used, which prevents such a refractive crack
index show that the / oractically invisible that after

or another liquid in contact with water / have a low degree of swelling and the are essentially stable to atmospheric UV radiation.

409840/0831

The method according to the invention is in particular also applicable to glass panes applicable, which are essentially retained in their original form and arrangement, for example on glass panes in frame. The liquid, free of volatile solvents, is polymerizable on these panes Given monomer mixture. This mixture penetrates the crack fills it out and polymerizes in it under the action of a hardener at the normal temperature of the glass to a mass, whereby during the polymerization lcdne further magnification of the Jump occurs. The refractive index of the polymerized mass is in such a range that the crack after removal of excess mass from the glass surface for the eye noticeable

or is practically invisible. The mass binds the opposite Surfaces of the crack with sufficient strength so that no Enlargement of the jump is caused.

It has been found that cracks in glass objects after this procedure can be easily repaired without replacing or removing the glass. If the Refractive index of the polymerized mass is chosen so that it is comparable to that of the glass, so slit the repair

not on. In addition, this process makes it possible to restore the original strength of the glass to a substantial extent. With the preferred repair materials the original strength can be restored to at least 50 percent.

409840/0831

It has been found that cracks in glass plates, in particular.

or hairline cracks

if the hair is cracked / are very thin. Kick frequently Jumps of 1 u width. It is therefore necessary that the polymerizable materials used in the process according to the invention * mix penetrate into these cracks and fill them in. When it comes to restoring strength in the area of the jump arrives, no volatile solvents must be present in the polymerizable mixtures, which gradually evaporate and leave vacancies. Such vacancies would not only reduce the number of jobs Strength of the repaired glass object lead, but they

would also cause the repair site to be visible and thus noticeable.

The polymerized mass must be transparent, because when it is present

only

the repair area against a / translucent or opaque mass would be visible. Slight discolouration of the polymerized mass is permissible because the repair areas are thin and therefore the color is not particularly evident. However, the polymerized mass should not have a very strong color, when it is to be used to repair colorless glass. The polymerizable Mass may be colored, although this is not essential.

The refractive index of the polymerized hats should be close to the refractive index of the glass so that the repair area, for example on window panes, is inconspicuous. The refractive indices of different types of glass are different, so that the polymerizable mixtures are to be selected so that one

409840/0831

reasonable adjustment of the refractive indices of the polymerized Mass is achieved with the glass to be repaired.

The refractive indices of commercially available glasses that are used for normal glazing and decorative purposes as well as for optical purposes are in the range of about 1.48 to 2.18. The refractive index of the polymerized should also be in this range Mass lying. The values for the refractive indices depend slightly on the wavelength of the light used * For the sake of simplicity, the values given here all relate to measurements with yellow sodium light. Based on these Changing the refractive index as a function of the wavelength allows an exact match of the refractive indices of the glass and the polymerized mass can only be achieved at a certain wavelength. However, when using the in the method according to the invention preferred, curable epoxides-containing mixtures a good agreement over the whole Achieve wavelength range of visible light, as the change in the refractive index of the masses produced from it about shows the same wavelength dependence as the refractive index of glass. -

The refractive indices of different types of glass fall in relative terms narrow areas. Soda glasses for common uses, such as window glass and pane glass, have a refractive index. in the range of 1.513 to 1.527. Borosilicate glasses with good resistance against thermal shock, which are used, for example, as laboratory glasses, have a refractive index from 1.509 to. Lead crystal glasses, which are used in particular as jewelry j

409840/0831

Glasses used have a refractive index in the range from 1.53 to 1.57. The most important * purpose of the invention The procedure lies in the repair of window and pane glass. In this case, the polymerized mass should have a refractive index in the range from 1.513 to 1.527 or roughly speaking in the range from 1.51 to 1.53. The index of refraction of English window glass is around 1.517.

The success of the method according to the invention is of course greater, the more precisely the two refractive indices match. However, because of minor changes in the batches of glass, it is not practical in every case for an exact match of the refractive indices. However, in special cases it is possible to achieve a practically exact match.

If the repair site is to be virtually invisible, then it is desirable that the refractive index of the polymerized The mass that is in the glass crack is as close as possible to the refractive index of the glass. This index of refraction the polymerize mass should then be reached when the polymerization is essentially complete in the glass crack, since the refractive index of the polymerizable mixture during the Polymerization can change slightly, and the fourth achieved in the glass crack can differ from the value achieved at Polymerization of a larger amount is achieved.

Conveniently, the refractive index is measured before use to repair a particular glass by the fact that mixture according to the invention polymerized under such conditions, _j

409840/0831

which correspond as closely as possible to the conditions prevailing during the jump, and then measure the refractive index. For example the repair material can be placed between two transparent

or plates
Foils / (to exclude oxygen) or between two ent-.

or plates removable (e.g. by peeling off or peeling) foils / polymeric

man

were sated, whereupon / measures the refractive index. Because of the environmental influences the refractive index is often influenced during the polymerization, it is expedient to carry out this polymerization to be carried out under conditions that correspond as closely as possible to the conditions in the jump.

There are several methods of determining the refractive indices of polymerized masses. One method is to divide the mass into different colorless liquids one at a time to immerse, whose known refractive indices form an increasing series. The refractive index corresponds to that of the examined Hasse the refractive index of the liquid, making the mass almost completely invisible.

The most direct and easiest way to see if a specific Mixture is suitable, for example, for repairing window glass, is to jump directly into such a mixture To repair glass, and determine whether the repair point is visible. This method is very precise as the eye is very sensitive to local differences in the refractive index is. For this reason it is generally not necessary to make the jump completely invisible, it is sufficient to when he is no longer noticeable.

409840/0831

The polymerized mass must be relatively solid and form a strong chemical bond on both sides of the crack. In the case of narrow jumps, it is unlikely that the surfaces of the jump will get dirty. However, gases can be present on the surfaces be adsorbed. It is therefore necessary that a firm chemical bond be achieved even in the presence of these adsorbed molecules

Jumps
will. In the case of wider areas, any dirt that may be present will be removed before or during the repair. For example, prior to repair, such dirt can be removed by rinsing with a volatile solvent, such as alcohol, and then evaporating the solvent. Incorporation of a compound with silane functional groups into the solvent can improve the strength of the subsequent repair. sern. Preferably, the cracks are repaired immediately after they occur so that the problem of dirt removal does not arise.

Masses that remain sticky are useful in the process of the invention not suitable as they have a relative movement of the two

walls
Jump * would allow. When cleaning a repaired pane of glass or if wind occurs, the two sides could shift, which would lead to the absorption of dirt and the visibility of the crack and, more importantly, the further spread of the crack over the glass pane.

To check whether a certain polymerizable mixture is used Repair of cracks by binding the opposing jump surfaces with sufficient strength is suitable so that _j

409840/0831

If the crack is prevented from spreading, the mixture can be used to repair a standard crack in a pane of glass will. The repaired pane is then subjected to the usual cleaning loads.

To generate a standard jump, as understood here is, a pane of English window glass with the dimensions 165 χ 203 mm and a thickness of 2.4 mm in one length slightly scratched from 102 mm. At a distance of 51 mm from the longer edge, scratches are made parallel to the shorter edge. Then the disc is fixed with a solid counter

Beat v replaced./
stood a short, firm / the jump obtained is called

Called standard jump.

Then such a standard jump is made with the one to be examined The mixture was repaired and subjected to a normal cleaning load. The usual cleaning load here is as follows defined: A pane of glass with a standard jump is attached to the two shorter ones in the horizontal direction Pages supported. The center of the plate is carefully loaded with a 3 kg brass weight. If there is no noticeable expansion of the repaired crack in this stress test, then so has passed the test.

During the polymerization, the mass must not open up and widening the crack noticeably, nor is it allowed to contract noticeably, which would create cavities, through which the * repair point. would be easily visible. To the occurrence to avoid hollow spots in the repaired crack, dür-L

409840/0831

no gaseous products are released during the polymerization will.

The polymerizable mixture can be a monomer or a mixture of monomers contain, its polymerization by a cataly-t or by irradiation, for example with UV light, catalyzed will. Preferably, however, self-curing mixtures are used, i.e. mixtures which contain at least one polymerizable Contain monomer and a hardener. Since the cracks are generally narrow, it is important that most, if not all, the molecules present in the jump serve a specific purpose. So should practically all polymerizable molecules react with each other so that sufficient repair strength is achieved and an expansion of the crack is prevented. All other molecules present are said to have a special, necessary one Fulfill function. Examples are UV absorbers and non-volatile plasticizers. In general, in the invention. moderate mixtures contain at least two monomers. In general, no monomer alone exhibits the required properties in terms of viscosity and refractive index, while a mixture of monomers in the polymerization to the desired Properties leads.

The method according to the invention is particularly suitable for repair of cracks in glass sheets, e.g. window panes, where the cracked or broken glass is essentially in its original position and arrangement is retained. So is a sheet of glass attached to a window frame after a full jump into two or more parts in general

409840/0831

common by the framework essentially in its original Position held so that the crack can be repaired. In addition, the glass will hold in the event of a partial crack itself and, if necessary, the frame mechanically fasten the opposite sides of the jump to one another. In the latter The case can change the dimensions of the jump along its course change considerably, for example from a relative wide crack at its open end to a hairline crack or molecular crack at the closed end.

Although the method according to the invention is particularly useful for repair of cracks in glass objects, their use is to repair them completely in two or more parts broken glass objects not excluded. In any case, the mixtures used according to the invention must be in the Be able to penetrate cracks in glass objects.

The polymerizable mixture must be liquid and in a jump can penetrate and fill it out. A factor affecting penetration the ability to wet glass appears to be affected. To ensure effective penetration of the mixture and to achieve a strong bond, the mixture must be capable of wetting glass. Since the cracks are relatively thin, a strong capillary effect occurs, which pulls the mixture into the crack and causes it to fill up. This effect depends of course on the width of the jump. The widest jumps, which are expediently made according to the method according to the invention. Ren can be filled, have a width of about 500 u Surface tension of the used in the method according to the invention

409840/0831

ten mixtures that this capillary force affects does not seem particularly
/ to be critical, since capillary force is generally very high

is high and is only a limiting factor for very large jumps. A typical fourth for surface tension the mixture used in the process according to the invention is 38 dynes / cm.

The capillary action that draws the mixture into the crack is sufficient to displace the air from the crack by the mixture so that the crack is filled without leaving any visible air holes.

The capillary effect is counteracted by the viscosity of the mixtures used. The mixture must therefore be used in such a way that it penetrates the crack before substantial polymerization and a consequent increase in viscosity occurs. In addition, the viscosity of the mixture must be such that, when applied to an upright glass plate, it penetrates the crack before it completely drains off the surface and moves away from the crack. This is important for panes of glass that are to be repaired on the spot, as a large proportion of the panes of glass that are inserted are in the upright position.

The upper viscosity limit for a freshly made, in-process The mixture to be used according to the invention appears to be about 1000 cps. This fourth becomes when the Geaiischoc hardens exceeded. But it seems that he is the upper limit if the mixture penetrates into a jump and fills it out

409840/0831

len should. At values above this limit, the capillary forces generally appear to be insufficient to pull the mixture into leaps and bounds before it polymerizes. Apparently there is no significant lower limit to the viscosity. The only condition is that it must penetrate the crack faster than it runs off an upright glass plate; If a liquid mixture wets the glass, even if most of the liquid runs off a drop applied to the glass surface, the crack is nevertheless filled first. Investigations have been carried out with liquids of known surface tension and viscosity that are not suitable for repairing cracks. These liquids were applied to upright glass panes with a horizontal jump. It has been found that, for example toluene (surface tension 29 dyn / cm at 2Q ⁰ C and viscosity of 0.59 cp at 20 ° C) and benzene (surface tension '29 dynes / cm at 20 ° C and viscosity of 0.65 cp at 20 ⁰ C) penetrate in jumps. Even ether, the surface tension of 17 dyne / cm at 20 ° C and viscosity be 0.23 cp at 20 ⁰ C, penetrates halfway into cracks before it runs off the glass.

The rate of polymerization should not be too high, since otherwise the useful life of the mixture is too short. Likewise, the development of heat during the polymerization must not be too great, otherwise it will jump during the polymerization so much heat developed that further jumping or widening of the jump can occur. Commercially available, already

Common

mixed with a hardener / should remain usable for several hours. On the other hand, the polymerization should cease to be sufficiently rapid

409840/0 831

run to achieve a solid repair in a few days at normal temperature. The rate of polymerization of the mixture depends on the ambient temperature of the glass. Thus, in cold weather, for example at temperatures below ⁰ ° C., a faster rate of polymerization is required than in milder weather.

In the process according to the invention, many epoxides can be used together with suitable hardeners, such as amines, can be used. Appropriate mixing of the epoxides will cause the epoxides to polymerize Mass exactly the required refractive index and suitable properties in relation to the ability to penetrate into the Crack and have viscosity. Epoxides produce a firm bond to acidic glass surfaces and are therefore in the invention Method particularly preferred.

In general, it is preferred to use a mixture of at least two copolymerizable monomers which together contain the have physical parameters required in the method according to the invention.

It has been found that a greatly improved bond of the polymerized mass to the walls of the crack can be achieved can, if the inventive polymerizable mixtures contain a compound with active silane groups as these groups easily react with the surfaces of the glass crack and also facilitate the penetration of the mixtures into the jump. Apparently, allow mixtures according to the invention with a high proportion of active silane groups a greater strength

409840/0831

repaired crack. Among active silane groups are to understand such flu caused by water or other hydroxyl groups containing compounds are hydrolyzed to a silanol. This can be done with those on the glass surface OH groups form a chemical bond.

The active silane groups can be in one of the constituents of the polymerizable mixture or in a constituent of the polymerize mass incorporated during polymerization will be present. However, these groups are preferably present in one of the constituents of the polymerizable mixture, since the mixture, as already stated, preferably contains the smallest possible number of components.

In the case of polymerizable mixtures based on a Epoxide and a hardener, such as an amine, the active silane groups can be present on the hardener and / or on the epoxy monomer be.

For example, amines of the general formula can be used as hardeners

H ₂ N- (CH ₂ ) - / HN (CH ₂ J _n Z _1n - Si / OR / ^

in which R is an alkyl radical, preferably a lower alkyl radical, in particular the methyl or ethyl group, ρ an integer with a value from 1 to 10, η a small integer and m 0 or an integer with a fourth from J to 5 , y has the value 1, 2 or 3 and ζ the fouri / 1 or 2, where the sum of y and ζ · 3. Specific examples of these amines are H ₂ N- (CH ₂ ) ₃ -Si- (OCH ₃ ) ₃ and H ₂ N- (CH ₂ ) ₂ ~ NH- (CH ₂ ) ^ - Si- (OCH ₃ U

409840/0831

To the bonding of the glass surfaces and the penetration of the polymerizable To improve mixture in the jump, it is appropriate that the mixture has a relatively large number of active Contains silane groups. Accordingly, epoxy monomers containing active silane groups are preferably used. Examples therefor are compounds of the general formula

in which R, y and ζ have the above meaning and R is a divalent alkenyl chain whose carbon chain can be interrupted by ether oxygen atoms, s has the value 0 or 1 and R ^{2 is} an epoxy group, ie -CH-CH ₂ , or an alicyclic ring which is substituted by an epoxy group, e.g.

means. An example of these monomers is (CH ₃ O) ₃ Si (CH ₂ J ₃ OCH ₂ CH-CH ₂

Also suitable as polymerizable mixtures are those which contain an unsaturated polyester resin, for example a copolymer of polyethylene glycol maleate in a mixture with methyl methacrylate or some other diluent which achieves the desired viscosity and index of refraction will. These mixtures can also contain at least one component with active silane groups. The unsaturated polymerizable Monomer can therefore have the general formula

R ₃ (R ² ) _t Si / ÖR / _y R ₂

in which R, y and ζ have the above meaning, t has the value 0 or 1, R is a connecting carboxylic acid radical of the general j

A098A0 / 0831

my formula

-C (0) 0 (CH ₂ ) _s - or -OC (O) (CH ₂ ) _s -

denotes, s is a small integer, R ^ denotes a radical of the general formula -CR = CH ₂ and R denotes a hydrogen atom or a linear alkyl radical, for example the methyl group.

Examples of such monomers are vinyl trimethoxysilane and

Another compound that acts in a similar way is

CH ₂ = CH-Si / Co-OC (CH ₃ ) ₃ 7 ₃ .

These mixtures containing an unsaturated polyester can be activated by initiators which form free radicals or by UV light, i.e. in bright sunlight, can be polymerized.

The polymerized mass should have good weather resistance. In order to achieve this, stoichiometric ratios of the constituents of the polymerizable mixture are chosen, so that a practically complete polymerization is guaranteed. Furthermore, a reaction accelerator, e.g. triphenyl phosphite, can be added, which also improves the water resistance of the polymerized Mass is achieved.

Furthermore, it seems necessary that the polymerized masses in the cracked state in order to achieve good weather resistance a low degree of swelling after contact with water and other compounds, such as ammonia or alcohol, which are often found in,

409840/0831

Window cleaning agents are included, should have. This low degree of swelling is necessary for the strength not to be to adversely affect, to keep the changes in the refractive index minimal, to noticeable stresses at the repair point prevent and achieve that no stickiness occurs on the surfaces of the crack. The degree of swelling of the hardened Kass is related to its water absorption, which can easily be determined by taking samples of the hardened registers are immersed in water or other media for a certain period of time and their weight gain is determined. Preferred compositions show less than 1.5 percent weight gain in this test after being in water for a week have been immersed. After 1 month of immersion, the weight gain is preferably at most 2.5 percent. Similar values are obtained when the samples are immersed in 5% aqueous solutions of ammonia or alcohol.

Furthermore, the polymerized masses should essentially be affected by atmospheric UV radiation, i.e. UV radiation of the The wavelength and the intensity as it occurs when exposed to sunlight are essentially not affected. In this connection it is important that the polymerized mass does not degrade to such an extent upon exposure to light is that the bond between the surfaces of the crack

g © ^v caused /

seriously weakens or becomes noticeably yellow in color. To avoid this, the mixtures of the invention can be of a known type UV absorber included. Examples are 2,1-dihydroxybenzophenone, 2-hydroxy-1-methoxybenzophenone, 2,2'-dihydroxy-4,4 · - dimethoxybenzophenone, 2,2-dihydroxy-4-methoxybenzophenone,

409840/0831

2.2% 4,4'-tetrahydroxybenzophenone ,. Phenyl salicylate, 1-butylphenyl salicylate, S-chloro ^ -hydroxybenzophenone, dibenzoylresorcinol, 2,2 · -dihydroxy-5-diethylphenol-benzotriazole and 2,2'-dihydroxy-4-octyloxybenzophenone.

Since the polymerizable mixture must be polymerized at room temperature, i.e. at the temperature at which the glass to be repaired, it must be sold in a non-reactive form. For example, it can be in the form of two separate ones Components are sold that are mixed just before use. For example, one uses a common one Two-component pack in which the components can be kept separate until use, particularly suitable are individual plastic bags that are torn by a This membrane separates the two components from one another until they are used. When using the membrane is ruptured and the two components are mixed within the sachet. Then the Open the sachet and use the mixture. Another possibility is to use polymerizable mixtures, which do not react until they come into contact with moisture, air or other compounds, for example a. ■ Acid coating on the glass. In this case, the polymerizable Mixture can be sold in an airtight sealed single package.

The inventive method is particularly suitable for permanent repair of household window panes, but it can also be used for the "temporary or permanent repair of other

409840/0831

Ren glass objects are used, for example shop window glasses. It is also suitable for permanent Repair of antique glass objects and glass figurines.

The strength of a repaired by the method of the invention Crack can be detected after repairing a standard crack. The forces are measured that necessary to break the repaired glass. Then .will be compared with the corresponding forces that lead to the break a corresponding non-cracked glass plate are necessary. In detail, such a test runs, for example, as follows:

A glass plate measuring 165 χ 203 mm and a thickness of 2.4 mm is scored over a length of 102 mm. You scratch at a distance of 51 mm parallel to the long edge, Then the target is hit with a solid object, a short, firm blow,

which creates a standard jump. The pane is then repaired according to the method of the invention and then examined for their breaking strength. The board is clamped at the edges parallel to the score line. Then will on the parallel edge at a right angle to the disc, which is further away from the scoring line, a dosed and recorded Bending moment applied. '

The stated values are average values from several tests, i.e. 5 to 10. These values are given with average,

409840/0831

Comparative values obtained after testing several standard glass panes (i.e. 5 to 10) without a crack will.

The examples illustrate the invention. Unless otherwise stated, all parts of the data relate to weight.

example 1

A mixture with a refractive index of 1.517 is produced from diglycidyl phthalate and diglycidyl adipate. 2 g of this mixture are _{mixed with 2 ml (CH 3} O) ₃ Si (CHg) ₃ NH (CHg) ₃ NH ₂ (commercial product from Dow Corning with the designation Z6020). Drops of this mixture are applied to the crack in a pane of glass with the help of a glass rod. The crack is located in a pane of glass of the dimensions

Edge

152 χ 203 mm and was knocked on a / . generated. Within a few seconds, the liquid penetrates into the crack due to the capillary action, which is the result it can be seen that the damaged area becomes invisible. Within Polymerization occurs after 6 hours. The repaired glass withstands a moment of 25,000 cm / g without breaking. The corresponding value for the unrepaired glass is 3000 cm / g. At this stage the excess polymer becomes removed with a razor blade. The entire glass pane is then cleaned with a commercially available window cleaning agent. An acceptable crack repair is obtained, with strengthening

409840/0831

The disc's speed and clarity have been restored to a high degree.

Example 2

According to Example 1, a mixture of diglycidyl terephthalate and allyl glycidyl ether with a refractive index of 1.517 were used to repair a cracked glass. The optical Clarity and much of the physical strength restored.

Example 3

An epoxy mixture with a refractive index of 1.517 at 20 ° C. is produced from 50 parts of Epikote 828 and 50.8 parts of Epikote 871. Epikote 828 is an aliphatic polyepoxide from Shell. It has an epoxy equivalent weight of 190, an average molecular weight of 370 and a viscosity of 125P at 25 ⁰ C. Epikote 871 is also an aliphatic polyepoxide from Shell. Its epoxy equivalent weight is 390 to 470 and its viscosity at 25 ° C is 400 to 900 cps. 5 parts of this epoxy mixture are mixed with 1 part (CH ₃ O) ₃ Si (CH ₂ ) ^ NH (CH ₂ ) ₂ NH ₂ , which is used to harden the epoxy and to attach the mixture to the glass. After thorough mixing, samples of this mixture are applied in small quantities to 100 mm long cracks in glass panes measuring 165 × 205 mm. In order to obtain reliable test results, 100 panes of glass are repaired in this way. The penetration of the mixture into the cracks takes place quickly, which is indicated by the optical disappearance of the damaged area

will. After standing for one day at room temperature, the PoIy-L

409840/0831

degree of merization sufficient so that the excess polymer can be removed with a sharp blade. The damaged area is then polished with a cloth that is covered with is wetted with a standard window cleaner, smoothed. After that, the damaged area is almost invisible. By breaking tests it can be seen that the panes of glass after 7 days have an average of 45 percent of the average strength of a have undamaged disc. These tests are carried out with one edge of the glass pane clamped and the moment applied to the other edge is measured, which is necessary to break the glass plate.

Example Λ

From 52 parts of Epikote 816 and 48.3 parts of Epikote 871 a mixture having a refractive index of 1.515 is prepared at 20 ⁰ C. Epikote 816 (commercial product from Shell) is a liquid diglycidyl ether of bisphenol A with an epoxide equivalent weight of 200, an average molecular weight of 348 and a viscosity of 15 P at 25 ° C

18 parts of this mixture are _{mixed with 2 parts (CH 3} O) ₃ Si (CH ₂ J ₃ OCH ₂ CH-CH ₂ (commercial product from Dow Corning under the name Z6040) and 3 parts triethylenetetramine as hardener Mixture applied sparingly along cracks in 100 panes of glass according to Example 3. After 10 days at room temperature, the repaired panes have on average about 40 percent of the strength of the undamaged panes.

409840/0831

Example 5

From 52 parts of Epikote 815 and 48.2 parts of Epikote 871 a mixture having a refractive index of 1.517 is prepared at 20 ⁰ C. Epikote 815 is a liquid diglycidyl ether of bisphenol A diluted with butyl glycidyl ether (commercial product from Shell). The epoxy equivalent weight is 190, the average molecular weight 330 and the viscosity at 25 ⁰ C 9P. 36 parts of this epoxy mixture are mixed with 4 parts

/ Ox

.len (CH ₃ O) ₃ Si (CH ₂ J ₅ OCH ₂ CH-CH ₂ and then 1 part phenol and 8 parts diethylenetriamine are added the polymerisation is somewhat faster due to the addition of phenol. After 8 to 10 hours polymerisation at room temperature, the excess polymer is scraped off * Then it is polished with a cloth soaked with a window cleaning agent Repaired glass panes have an average of about 40 percent of the strength of the undamaged panes After the panes have been exposed to the weather for 30 days, the repaired areas do not show any damage.

Example 6

52 parts of Epikote 816 and 48.3 parts of Epikote 8 ¹⁷ I become one

at 20 ° c epoxy mixture with a refractive index of 1.515 / produced.

A hardener mixture is then prepared from 50 parts of (CH ₃ O) ₃ Si (CH ₂ ) ^ nHCH ₂ CH ₂ NH ₂ and 50 parts of triethylenetetrainin. 10 parts of the epoxy mixture are mixed with 2 parts of the hardener mixture. According to example 3, _j

409840/0831

repaired damaged glass panes. After one day of polymerization the excess polymer is removed. After a week you can see that the repaired panes are average Have regained 35 percent of their original strength.

B is ρ i e 1 7 parts of a resin mixture of the following components:

Epikote 828 9 parts

Epicote 871. 10 parts

Vinyl cyclohexane dioxide

(Commercial product from Union Carbide Company under the name ERL 4206 1 part

/ 0.
(CH ₃ O) ₃ Si (CH ₂ UOCH ₂ CH-CH ₂ 7 parts

Butyl glycidyl ether 1 part

are mixed with 1 part of a hardener of the following composition:

Diethylenetriamine 1 part

Synolide 96O

(Polyamide hardener for epoxy resins from Gray Valley Products Limited with a Amine value of 350 mg KOH / g and a viscosity at 25 ° C of 200 to 400 Cs), 18 parts

The mixture obtained has the following properties at room temperature on:

Viscosity 148 Cs

-1 surface tension 35.0 dyn. Cm

Refractive index 1.4970. . ;

Some of this material is then applied to the surface of Glass plates applied with standard cracks. The rest is poured into molds. After a few minutes the capillary _j

409840/0831

- 2 B -

effect, a sufficient amount of the material has penetrated the cracks to completely remove the air from them and reduce the visibility of the jumps considerably. The material has gelled 24 hours later. The excess Material is then removed from the glass surface with a razor blade removed. A weak but no longer clearly visible repair area remains. About 1 week later after the hardening is judged to be complete and the crack is only visible on very careful examination, the glass panes are broken in the manner described above. It can be seen that 50 percent of the average original strength have been restored. At the same time, the hardened samples are removed from the molds and roughly cut into cubes weighing 11 to 16 g. These cubes are placed in water, a 5 percent aqueous ethanol solution or a 5 percent aqueous ammonia solution soaked. The weight gain achieved is shown in the following table:

Table I.

liquid Weight ratio: axle (%) 1 month ! water
5 % ethanol
5 % ammonia 1 week 2.33
2.78
2.02 1.11
1.52
0.90

In addition, it is determined to what extent the strength of the repair points after immersing the repaired glass panes for 11 days subsides in water. It is found that the original strength of the repair sites increased by about 26 percent

jji lets go.

409840/0831

Example 8 A mixture of the following ingredients is prepared:

Styrene-modified, slightly stabilized unsaturated polyester resin
(Crystic 19IF, commercial product from Scot-Bader Limited) 34 parts

₃₃ Si CH = CH ₂

(Commercial product from Dow Corning under the trade name Z-6075) ■ 4 parts

Styrene 4 parts

Catalyst M

(Commercial product from Scot-Bader Limited for use with Crystic 191E) - 1 part

Accelerator E

(Commercial product from Scot-Bader Limited for use with Crystic. 191E) 0.5 parts

Immediately after mixing, the product has the following properties:

Viscosity at 20 ^° C. 40 cp

Surface tension at 20 ^° C. 36 dynes / cm

Refractive index 1.526

The mixture is applied to the surface of glass cracks. After hardening, the visibility of the cracks is considerable reduced. The panes regain 15 percent of the average strength of undamaged panes.

Example 9 2.75 parts of a resin mixture with the following ingredients:

409840/0831

- 28 - Epicote 828 2413965 Epicote 871 9 parts Vinylcyclohexane dioxide (ERL4206) 10 parts (CH ₃ O) ₃ Si (CH ₂ ) ₃ OCH ₂ ^ CH ₂ Part 1 . . Butyl glycidyl ether 7 parts are made with 1 part of a hardener mixture Part 1 Diethylenetriamine Synolid 960 Part 1 18 parts

mixed. This mixture has similar properties to the product obtained in Example 7.

With this mixture, as in Example 7, 6 panes of glass with standard cracks are repaired. After 7 days the firmness is of the repaired panes an average of 59 percent of the undamaged panes.

Samples of approximately 10 g each are hardened from this mixture to form blocks. Subsequently, the water absorption this shaped body measured. Over a period of 4 to 11 days, the water uptake remains constant at 0.93 percent.

Example 10 A mixture of the following ingredients is prepared:

Styrene modified, light stabilized

unsaturated polyester resin

(Crystic I9IE) 34 parts

Methyl methacrylate 4 parts

Catalyst M

(for use with Crystic 191E) 1 part

Accelerator E

(for use with Crystic 19IE) 0.5 parts

409840/0831

(CH ₃ O) ₅ Si (CH ₂ J ₃ OC (O) C (CH ₃ ) = CH ₂

(Trade product from Union Carbide under the trade name
Promoter A 174) 4 parts

In summary, it can be stated that the mixtures used in the process according to the invention have sufficient penetration capacity in which they must show jumps, i.e. they must be within a maximum of 30 seconds and preferably within Penetrate a standard jump for a maximum of 10 seconds. In addition, the mixtures are allowed to change in volume after polymerization of at most 20 percent and preferably at most 10 percent.

If solvents or additives are used in the mixtures, they may be used at the reaction temperature or at the Ambient temperature must not be volatile, otherwise bubbles would form in the repair area. If the addition of a solvent is desired, it is appropriate to use a solvent that is compatible with the copolymerizable monomers Mixture reacts.

409840/0831

Claims (12)

- 30 claims Method for repairing cracks in glass objects, in particular glass panes, characterized in that that one uses liquid mixtures consisting of at least two copolymerisable monomers which wet glass, in Penetrate cracks from upright glass and fill them in faster than they run down from upright glass, which have a viscosity of at most 1000 Cp before the start of a noticeable polymerization, which are free of volatile, non-copolymerizable solvents and which are without substantial expansion or contraction, without development gaseous products and without external heat exposure under at normal temperatures in the presence of a hardener or / iSin effect from active radiation to polymerize to transparent masses, which the two opposite surfaces of Bind cracks in the glass with sufficient strength to increase the size of a normal crack in a pane of glass To prevent the application of a load that is usual in cleaning, which have such a refractive index that the jump for the eye becomes inconspicuous, which show a low degree of swelling after contact with water or other liquids and which are essentially stable to atmospheric UV radiation. 2. The method according to claim 1, characterized in that a mixture is used which contains at least one compound with active Contains silane groups that can react with at least one other component of the mixture. 409840/0831 3. The method according to claim 1, characterized in that a mixture is used which consists of at least two monomers and a hardener. 4. The method according to claim 3, characterized in that a mixture of low molecular weight curable epoxy resins is used. 5. The method according to claim 3, characterized in that an amine of the general formula is used as the hardener: HM t / " ¹ U \ IxXVX { ΓΊΙ \ / GI / i \ O '/ D _O M-1 L> ii _n / _ - / XiWvLrJCl ₀ J _ / _ öx / Un. / Rt / ^ ^ p ^ IJT m "~ y ζ in which R is an alkyl radical, ρ is an integer with one Is a value from 1 to 10, η is a small integer, m has the fourth 0 or is an integer with a value from 1 to 5, y is 1, 2 or 3 and ζ is 0, 1 or 2, where the sum of y and ζ is 3. 6. The method according to claim 3, characterized in that the mixture is a curable, monomeric epoxide of the general formula contains: R ² - (R ¹ ) _s -Si / OR7 _y R ₂ in which R is an alkyl radical, y has the value 1, 2 or 3, ζ has the value 0, 1 or 2, where the sum of y and ζ is 3, s has the value 0 or 1, R is a divalent alkenyl chain or a divalent alkene interrupted by ether oxygen atoms nyl chain and R denotes an epoxy group or one through one Means epoxy group substituted alicyclic ring. 409840/0831 7 «The method according to claim 1, characterized in that a mixture is used which is at least one polymerizable Monomer of the general formula contains: R ⁵ (R ² ) _t Si / ÖR7yR _z
in which R is an alkyl radical, y has the fourth 1, 2 or 3, ζ has the value 0, 1 or 2, where the sum of y and ζ is 3, t has the value 0 or 1, R is a bonding radical having a carboxyl group of the general formula -C (0) 0 (CH ₀ ) _o - or -OC (O) (CH ₀ ) 6 ύ C. means s is a small integer, R a remainder of the general formula -CR ⁴ = CH ₂ and R is a hydrogen atom or a straight-chain alkyl radical means. 8. The method according to claim 7 »characterized in that one a monomer of the formula OrIp = Oil / _ "\)" \ j used. 9. The method according to claim 6, characterized in that a mixture is used which additionally contains a hardener of the general Formula contains: H ₂ N- (CH ₂ ) _p - / βN (CH ₂ ) _n 7 _m Si / OR / _y R ₂ in which R is an alkyl radical, ρ is an integer with one Is a value from 1 to 10, η is a small integer, m has the value O or is an integer with a value from 1 to 5, y has the value 1, 2 or 3 and ζ has the value 0, 1 or 2, where is the sum of y and ζ 3. 409840/0831 10. The method according to claim 1, characterized in that a mixture is used whose refractive index after polymerization in a standard step in a pane of glass is 1.48 to 2.18. 11. The method according to claim 1, characterized in that a mixture is used whose refractive index after polymerization in a standard jump in a pane of glass about 1.51 to 1.53. 12. The method according to claim 1, characterized in that glass panes are repaired that are in their original position and arrangement are fixed by applying the mixture over the crack of a pane of glass, penetrating it into the crack and then polymerized to a mass at room temperature, which is inconspicuous to the eye and binds the opposite sides of the crack with sufficient strength, so that the crack is prevented from widening during the cleaning of the glass pane, and afterwards the excess polymerized mass is removed from the glass surface. 409840Λ0831