DE3112541A1 - METHOD FOR PRODUCING SAFETY GLASS WITH AN INTERLAYER OF POLYURETHANE - Google Patents

Description

The invention is directed generally to transparencies energy absorbing polyurethanes, especially those polyurethanes used in safety glass laminates are suitable and the glass composite material has a high impact resistance over wide temperature ranges to lend.

Safety glass is a well-known name for a glass plastic laminate that is constructed in such a way that that the severity of cuts caused by breaking glass is reduced. A polymer film is connected to a sheet of glass to form a laminate, so that when exposed to impact, the sufficient to break the glass, the broken glass to adhere to the film, and only to a minimal extent be scattered. A usable safety glass or glass composite material must firstly have a high level of energy absorption in order to minimize damage in the event of impact, and secondly, high tensile and tear strength in order to prevent the film from tearing open by fragments of glass; thirdly, a sufficient amount must be provided Adhesion of the layers should be present in order to largely avoid scattering of broken glass, so that the possibilities for cuts are reduced and fourthly, a high optical quality exhibit.

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The commercially available safety glass, particularly for automobile windshields, is common a three-layer laminate with two layers of glass and an intermediate layer of plasticized Polyvinyl butyral. However, a development can be observed, polyvinyl butyral through interlayers from other polymeric materials.

In U.S. Patent 3,509,015 there is a safety glass composite described with a cast and cured in place polyurethane interlayer, formed by reacting an organic diisocyanate and a curing agent with a prepolymer formed by reacting an organic diisocyanate and a Poly (oxypolymethylene) glycol. Suitable hardeners are polyols, especially those with at least three Hydroxyl groups per molecule and preferably used in conjunction with a diol, and polyamines, preferably used with a polyol. The reaction mixture is heated, degassed, introduced into a casting cell and hardened. The impact strength of the laminate formed is measured by the height from which a 227 g weight Steel ball can hit the laminate in free fall and this impact in a satisfactory manner survives.

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US Pat. No. 3,620,905 describes a colorless, optically clear thermoplastic polyurethane, that are used for security laminates can. This is made from diisocyanate-dicyclohexylmethane, a polyether or a polyester glycol and a diol with a molecular weight below 250. The polyurethane can be made in one step, as a quasi prepolymer, or with the known method for producing prepolymers. All of these ways of working are well known.

From US Pat. No. 3,764,457 a safety glass laminate is known with a thermoplastic polycarbonate urethane, which was formed from a cycloaliphatic diisocyanate to a monomeric aliphatic Diol and an aliphatic polycarbonate such as polyoxyethylene carbonate glycol.

U.S. Patent 3,900,446 describes a laminated glass composite material having a polyurethane interlayer contains, which was prepared from an isomeric mixture of 4,4'-methylene-bls- (cyclohexyl isocyanate), a polyester with a melting point above 42 ° C, which is a condensation product of a dicarboxylic acid and a divalent compound such as two active hydrogens (dihydric compound) and an alpha omega diol having 2 to 10 carbon atoms. The two-step process for making polyurethanes

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first includes the formation of a prepolymer and then the production of the polymer.

US Pat. No. 3,900,655 describes a safety glass laminate with a thermoplastic polyurethane intermediate layer, which is a reaction product of a cyclic nitrile carbonate and at least one Hydroxyl group is compound, for example a polyalkylene ether or a polyester glycol or a diol with primary or secondary hydroxyl groups and a molecular weight less than 250. Such polyurethane elastomers can be made by a variety of well known methods, for example the one-step method, the quasi prepolymer method or with full prior formation of a prepolymer.

U.S. Patent 3,931,113 describes polyester urethanes as having excellent properties for use in safety glass windshields. These polyester polyurethanes are formed from a cycloaliphatic diisocyanate, a diol having a low molecular weight and a hydroxyl end group comprising polyesters of polycaprolactone, poly (butylene adipate), poly (butylene acelate) or mixtures of that. These urethanes are preferably produced by a one-stage polymerization, with a flexible

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les polymer arises, which has a statistical distribution of the components.

From US Pat. No. 4,024,113 an energy absorbing safety glass laminate is known which is a polycarbonate urethane contains and this was formed from a cycloaliphatic ^! Diisocyanate, a diol with low molecular weight and a special polycarbonate diol made from a mixture of linear aliphatic and cycloaliphatic diols. The polycarbonate urethanes can be made either as single-stage block polymers or with prior formation of a prepolymer.

In U.S. Patent 4,035,548 there is a safety glass composite laminate described containing an energy absorbing interlayer that is fabricated made of a poly (lactone urethane), the molecular weight and structure of the lactone groups being carefully controlled to achieve maximum energy absorption and the best optical properties. That One pot method of polymerization is preferred versus the method of prior formation of prepolymers because of its simplicity and low Initial viscosity of the reactants.

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Numerous of the publications that deal with transparent energy-absorbing polyurethanes for interlayers deal with safety glass laminates, cite cycloaliphatic diisocyanates as preferred, in particular 4,4'-methylene-bis (cyclohexyl isocyanate) because of the combination of colorlessness, transparency and impact resistance. However, these diisocyanates are very expensive. Mixtures with small amounts of cheaper diisocyanates, for example toluene diisocyanate or Diphenylmethane diisocyanate or aromatic diisocyanates can only be used if the amount of aromatic diisocyanate is carefully controlled to avoid yellowing, cloudiness and reductions in the To avoid impact resistance.

It was an object of the present invention to provide a polyurethane composition which has low raw material cost, is easy to process and has a has better impact resistance than the typical commercial high-impact intermediate layers Polyvinyl butyral (vinyl interlayers).

This object is achieved by a method for producing a glass composite material according to claim 1.

Preferred embodiments of the invention are shown in Described subclaims.

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According to the invention, there is an intermediate layer for safety composite glass laminates created, wherein the polyurethane is a reaction product of toluene diisocyanate with a mixture of a polyalkylene ether glycol, a low molecular weight triol and an aliphatic diol.

The polyurethane interlayer of the present invention is made by one-step bulk polymerization the reaction mixture of tolylene diisocyanate, a polyalkylene ether glycol and a triol with low Molecular weight. It is produced by offset casting, i.e. the intermediate layer is formed by pouring the polymerization reaction mixture into a mold, forming a Polymer film, removal of the polymer film from the mold and subsequent lamination with a glass sheet. The offset casting technique is possible because the polyurethane composition according to the invention can easily be turned into a manageable film before it hardens completely. Partially hardened foils can be processed into laminate immediately after removal from the casting cell, but can also be temporarily stored for later processing.

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Detailed description of a preferred embodiment of the invention

A colorless liquid reaction mixture is produced from an aromatic diisocyanate, a polyalkylene ether glycol, a low molecular weight triol and a monomeric aliphatic diol. That Polyalkylene ether glycol has the following general formula:

(CH ₂ ) _n

OH

where η is preferably from about 3 to about 6, and m is preferably Assumes such a value that a molecular weight of the polyalkylene ether glycol of about 400 to about 2000 results. Polytetramethylene ether glycol with a molecular weight is very particularly preferred of about 1000.

The low molecular weight triol is incorporated to add side chains in the polyurethane structure produce. Preferred triols are monomeric aliphatic

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Triplet. The molecular weight and the ratio of triol in the reaction mixture are determined in accordance with the desired molecular weight between branch points in the polyurethane in order to achieve optimal To achieve properties. The most preferred triol is trimethylol propane. Other trifunctional Compounds such as triamines can also be used to create branches in the polyurethane chain to create.

Aliphatic monomeric diols are used as chain extenders for the polyurethane according to the invention. These have the general formula

HO ^ ^CH 2 * n ^0H

where η is about 2 to about 10. Other aliphatic diols, including substituted cycloaliphatic ones and secondary alcohols can also be used for the purposes of the invention, but are less so preferred as the functional chain extenders instead of the diols, as well as diamines. The preferred one Chain extender compound is 1,4-butanediol.

Aromatic diisocyanates for the production of polyurethanes are known prior art. A preferred one

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the aromatic diisocyanate for the production of the polyurethanes according to the invention is tolylene diisocyanate. A commercially available mixture of 65 % 2,4-toluene diisocyanate and 35% 2,6-toluene diisocyanate is preferred over an 80/20 isomer mixture because higher levels of 2,6-toluene diisocyanate appear to improve the resistance of polyurethanes at low temperatures. The proportion of diisocyanate in the reaction mixture is preferably approximately equivalent to the total amount of polyalkylene ether glycol, triol branching agent and diol chain extender. A stoichiometric imbalance of up to about 5 % excess of isocyanate groups does not yet impair the quality of the resulting polyurethane.

The substances described above are mixed together to form a colorless, transparent single-phase reaction mixture with low viscosity at room temperature. The polyalkylene ether glycol, polycaprolactone triol are preferred and monomeric aliphatic diol gently heated in vacuo and then placed in the reaction vessel introduced under nitrogen. Toluene diisocyanate is added to the mixture given above while stirring. The final blend preferably contains an adhesion control agent, as disclosed in U.S. Pat U.S. Patent 3,900,686. The mixture

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is degassed and placed in the film casting mold and the polyurethane interlayer films by polymerization educated. Preferably the degree of polymerization is at least about 50 before the intermediate layer is removed from the casting cell or mold.

The polyurethane intermediate layer, which preferably has a number average degree of polymerization between about 50 and about 125 are then laminated with glass sheets or panes of glass, preferably by the method described in U.S. Patent 3,808,077. The polyurethane fully cures in a conventional autoclave as a lamination step at a temperature of about 149 ° C. and at a pressure of about 13.8 bar for 45 minutes. It is however, it is also possible to cure the polyurethane essentially before lamination, because it has been found surprisingly was that a cross-linked fully cured polyurethane laminated as an intermediate layer with glass and a laminate with acceptable optical properties is obtained.

The invention will now be described in more detail using a specific example.

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example 1

Polytetramethylene ether glycol having a molecular weight of about 1000, which is semi-solid at room temperature, is heated. Polytetramethylenätherglykol, which is available under the name "Polymeg® 1000" by the Quaker Oats Company, is completely liquid at about 38 ⁰ C and then remains liquid at room temperature and desired for a long time long in a mixture with trimethylolpropane and butanediol. A mixture of 0.278 equivalents of polytetraraethylene ether glycol, 0.617 equivalents of 1,4-butanediol and 0.105 equivalents of trimethylolpropane are placed in a reaction vessel and stirred under vacuum from above. At a boiler temperature of about 30 ^° C., the vacuum is released and dry nitrogen is introduced and then 1000 equivalents of toluene diisocyanate are added. The toluene diisocyanate is preferably an isomer mixture of 65 % 2,4-toluene diisocyanate and 35 % 2,6-toluene diisocyanate and is available, for example, under the type designation "Hylene ™ 65" from duPont. The reaction vessel is then evacuated again in order to degas the reaction mixture. After releasing the vacuum and introducing dry nitrogen, the reaction mixture is poured as quickly as possible into a casting mold about 35.6 cm × 35.6 cm. The mold consists of poly

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tetrafluoroethylene-coated glass and the introduced layer of the reaction mixture is about 0.76 mm thick. After about Hours in the cell at a temperature of about 132 ° C, the polyurethane film has hardened to such an extent that that it is manageable and can be removed from the mold for the subsequent! ■ amination. The polymer has a urethane content of 23% and a Molecular weight between branch points of about 4850. The impact strength of this polyurethane in comparison Table I below shows the impact strength of polyvinyl butyral.

Table I.

Average penetration speed (m / h) (mph) temperature
-17.8oc 2I ₁ 49 ° C for safety glass laminate 23
17th 27
24 17th
12th Intermediate layer Polyurethane (example 1)
Polyvinyl butyral
(high impact vinal) , 1 ⁰ C , 6

The example described above serves to illustrate the present invention. The previously generally described Polyurethane essentially has a stoichiometric

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metric OH / NCO ratio, a urethane content between about 15 and 25% and a molecular weight between chain branch points in the range of 4000 to 8000. Other polyurethanes with the named Properties can also be used in the context of the present invention.

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Claims (9)

Dr. Michael Hann (1377) St / W Dr. H.-G. Sternagel Patentanwälte Marburger Strasse 38 6300 whose PPG Industries, Inc., Pittsburgh, Pennsylvania, USA METHOD FOR MANUFACTURING SECURITY GLASS WITH AN INTERLAYER OF POLYURETHANE Priority: April 30, 1980 / USA / Ser. No. 145,074 claims ί 1. A method for producing a glass composite material, characterized by a) pouring a one-part curable polyurethane reaction mixture into a film casting mold, wherein the reaction mixture contains 1) a polyalkylene ether glycol, 2) an organic compound with at least three active hydrogen atoms per molecule, 130064/0722 3) an organic compound with two active hydrogen atoms per molecule and 4) an aromatic diisocyanate b) polymerizing the reaction mixture and forming a self-supporting polyurethane film, c) removing the self-supporting polyurethane film from the mold, d) Laminating the polyurethane film with a glass sheet and e) thermal curing of the polyurethane. 2. The method according to claim 1, characterized in that the reaction mixture contains a) a polyalkylene ether glycol with 3 to 6 carbon atoms per alkylene group, b) a low molecular weight triol, c) an aliphatic diol
and d) toluene diisocyanate. 130064/0722 3. The method according to claim 2, characterized in that the reaction mixture contains a) a polytetramethylene ether glycol with a molecular weight of about 400 to about 2000, b) an aliphatic triol c) an aliphatic diol having 4 to 6 carbon atoms and d) an isomer mixture of 2,4-toluene diisocyanate and 2,6-toluene diisocyanate. 4. The method according to claim 3, characterized in that the reaction mixture contains a) a polytetramethylene ether glycol with a molecular weight of about 1000, b) trimethylolpropane, c) 1,4-butanediol and d) an isomer mixture of 2,4-toluene diisocyanate and 2,6-toluene diisocyanate, the Proportion of the latter is at least about 35%. 5. The method according to claim 1, characterized in that one is laminating the self-supporting poly 130064/0722 urethane sheeting with the glass panel before the polyurethane is thermally cured. 6. The method according to claim 1, characterized in that the lamination of the self-supporting polyurethane film with the glass sheet then performs the thermal hardening of the polyurethane. 7. The method according to claims 5 or 6, characterized in that that the polyurethane film at a temperature of about 149 ° C and with a pressure of about 13.8 bar (200 pounds per square inch) between two sheets of glass and forming larainate pressed. 8, method according to claim 7, characterized in that one has a polyurethane film with a thickness used from 0.5 to 1.5 mm. 9. Glass composite material produced by the method of claim 8. 130064/0722