STRUCTURE OF LOCK CASE FOR DOOR FRAMES AND DOOR FRAMES WITH SUCH CASE

Field of the invention

The present invention finds application in the field of doors and window frames and relates to a structure of a lock case, or similar mechanisms, particularly in fire- resisting doors and window frames.

In another aspect, the invention relates to a door or window frame containing the case of the invention.

State of the art

According to the latest fire prevention criteria, buildings are divided into sections or compartments which are separated by fire retardant barriers having the dual purpose of preventing fire from spreading to unaffected places, and of extinguishing fire by removing the required combustion air.

Doors and windows may be of the glazed or solid type. In the former case, one or more flame-resistant glass panels are inserted in a fire-proof structure, generally made of metal. In the latter case, the door or window, generally made of metal, consists of a boxlike structure having a minimum width of 45 mm to a maximum width of 150 mm for REI 180 doors and windows, containing a heat insulation typically consisting of multiple layers of glass wool and/or rock wool and an intermediate plaster panel, which are bound together with resin and/or alkaline silicates.

In the customary process of fabrication of a solid door or window, a sheet is folded to form a container in which the insulating layers and the binder are introduced one after the other. Then, the container is closed with another sheet to form the door or window.

In a prior art solution, the lock is introduced through an aperture formed in the thickness of the sheet, between the insulation layers, with a portion of such layers being possibly removed manually to create a space therefor, after completion of the door. The handle is mounted at a later time, using the previously formed holes, orthogonally to the lock plane.

This prior art solution has drawbacks in that it requires the formation of a hollow in the plaster panel and the mineral wool layers, long mounting times and manual operations, and it generates insulation dust.

A further drawback is the difficulty of interposing the required amount of heat insulation material between the lock and the sheet wall of the door or window. This problem is particularly felt because the new European testing standards require a movable temperature sensing thermocouple to be mounted on the side opposite the fire, 50 mm from the lock, whereby insufficient insulation invalidates the test.

In another prior art solution, the lock is fitted during fabrication of the door or window, when the latter is still open, while the insulation is introduced in the boxlike structure.

A drawback of this solution is that the lock has to be protected from the liquid resin that binds the insulation layers, from the polyurethane foam sealant, and from the aqueous polysilicate solution. Furthermore, the front side of this protection has to be manually removed during the finishing step.

According to another prior art solution, thermal insulation is provided by attaching a layer of intumescent material, generally the same material as is used for the seals, by an adhesive, to all the surfaces of the lock body, including the front side thereof.

The term "intumescent" relates to the property of a material to expand under heat, and to form a porous, insulating and substantially incombustible structure.

A drawback of this solution is that, before mounting the lock as set forth in one of the above solutions, at least six different specially shaped pieces of an intumescent seal, generally obtained by blanking and shaping, have to be manually positioned, so that the lock structure is wholly covered thereby.

A further drawback of all the above solutions is that they require one or more metal reinforcement members to be placed transversely within the thickness of the door or window, and to be fastened to the outer sheets, to prevent any inward bending thereof during handle mounting and normal use of the door or window.

Even when these reinforcement members are of small size, they act as a further thermal bridge, which promotes heat transmission from the hot wall to the cold wall, in an area where one of the testing thermocouples are mounted during the validation test, and this affects the test results.

Summary of the invention

A main object of the present invention is to obviate the above drawbacks by providing a method and a structure of a lock case for insulating doors and window frames, that allows quick lock installation.

A particular object is to provide a structure of a lock case for doors and window frames, particularly for fire-resisting doors and window frames, that is made of an incombustible material, providing effective thermal insulation.

A further particular object is to provide a structure of a lock case for doors and window frames, particularly for fire-resisting doors and window frames, that avoids the provision of protective covers on the lock.

Another object is to provide a structure of a lock case for doors and window frames, particularly for fire-resisting doors and window frames, that exhibits high performance, simple construction and low cost properties.

A particular object is to provide a structure of a lock case for doors and window frames, particularly for fire-resisting doors and window frames, that prevents any penetration of resins, glues or aqueous solutions from the outside.

Yet another object of the invention is to provide a structure of a lock case for doors and window frames, particularly for fire-resisting doors and window frames, that has a minimized number of parts and may be assembled in a very short time.

These and other objects, which will appear more clearly hereafter, are fulfilled by a structure of a case lock for doors and window frames, particularly for fire-resisting doors and window frames which, according to claim 1 , comprises a boxlike container made of a heat resistant material, which is a tray having side walls, a bottom wall 4, an attachment portion to be anchored to the door or window frame by suitable fastening means, characterized in that said heat-resistant material is an incombustible and/or intumescent plastic material.

According to a further aspect of the invention, a heat-resisting, particularly fire- resisting door or window frame is provided which, according to claim 43, is characterized in that it comprises at least one lock case or the like of this invention.

Thanks to this structure, the lock case is particularly effective in protecting the lock against resins and liquid glues, as well as particularly inexpensive and easily mountable to fire-resisting doors and windows.

Brief description of the drawings

Further features and advantages of the invention will be more apparent from the detailed description of one preferred, non-exclusive embodiment of a case according to the invention, which is described as a non-limiting example with the help of the annexed drawings, in which: FIG. 1 is an axonometric top view of a case according to the invention;

FIG. 2 is an axonometric bottom view of the case structure of FIG. 1 ; FIG. 3 is a broken away side view of the case structure of FIG. 1 , as taken along a plane A-A;

FIG. 4 is a top plan view of the case structure of FIG. 1.

Detailed description of a preferred embodiment

Referring to the above figures, a structure of a lock case is shown, which can be mounted to doors, windows, door windows, roof windows, glazing panels, fan shutters, etc.

These doors and windows may be fitted with auxiliary elements, such as locks, handle or panic bolt mechanisms or the like.

The terms "case" and "lock case" as used herein are meant to indicate an element for containing such auxiliary mechanisms.

The case may be used preferably, but without limitation, in fire-resisting doors and window frames.

According to the invention, the case structure is wholly made of a heat resistant material.

The term heat resistant material is meant to indicate a material that essentially retains its shape and does not burn at temperatures up to 200 ⁰ C.

Therefore, the case of such material may be introduced in the door or window frame even during its fabrication, before the painting process, in which temperatures above 200 ⁰ C may be reached.

According to this invention, such heat resistant material is a plastic material selected from the group consisting of extrudable or injection moldable thermoplastic blends which essentially retain their shape and do not burn at temperatures up to 200 ⁰ C.

The term thermoplastic blends is meant to indicate extrudable and/or moldable masses comprising, for instance, one or more polymers, copolymers or alloys, generally in granular form, organic and/or inorganic components and/or additives, mineral fillers, any processing aids, antioxidants, UV protecting agents, etc.

The mass may be partly or wholly premixed in a step that is known in the art as "compounding".

The term blends that essentially retain their shape is meant to indicate thermoplastic blends (masses) which are extruded or molded into products that essentially retain their shape and are not excessively deformed by heat at temperatures up to 200°C.

According to the invention, this plastic material may be a blend comprising one or more polymers selected from the group consisting of polyamides, polycarbonates, polyethers, polyimides, polyurethanes, polyolefins, polyarylsulfides, polysulfones, vinyl polymers and copolymers, mixtures or alloys thereof.

Without limitation, vinyl polymers or copolymers may include polyethylene copolymers such as ethylene-vinyl acetate copolymers (EVA), ethylene-vinyl alcohol (EVAL), ethylene acrylate such as ethylene methyl acrylate, ethylene ethyl acrylate, ethylene butyl acrylate, ethylene methacrylate.

Without limitation, polyether alloys may include poly(methyl phenylene ether)- polyamine, poly(methyl phenylene ether)-polystyrene, poly(methyl phenylene ether)-polypropylene, poly(methyl phenylene ether)-polyimide.

According to one embodiment of the invention, the thermoplastic blend comprises a polyamide selected from the group consisting of nylon-6 (PA6, polycaprolactam), polyamide nylon-66 (PA66, poly 1 ,6-hexamethylene adipoamide), semiaromatic polyamide or copolymers or mixtures thereof.

The term semiaromatic polyamide as used hereafter is meant to indicate a polymer containing the aromatic ring in the polymer chain, which is formally obtained from a diamine and a dicarboxylic acid. Without limitation, such monomers may include hexamethylene diamine, diaminodicyclohexyl methane, terephthalic acid, isophthalic acid, lauryl lactam.

Some of these semiaromatic polyamides are known as PA 6-3-T, PA 6T, PA6I6T, PA12/MACMI, PA12/MACTM, PA6I/PACM/PACMT.

PA 6T may be preferably used.

Furthermore, polyamides may be mixed with other polymers such as ABS, EPDM, EVA, SBR, PPE (polyphenyl ethers also known as polyphenyl oxides, PPO).

Without limitation, polyethers and copolymers and mixtures thereof may include polyphenyl ether, PPE with polystyrene, PPE with polypropylene, PPe with a polyamide, polyether imides.

A peculiar feature according to another preferred embodiment is that such plastic material is also incolbustible.

Incombustible materials are substantially non-flammable materials. Depending on their fire-retarding properties and use, such materials are divided into classes by national and international standard.

The term incombustible as used hereafter is meant to indicate an A1 , A2, B1 or B2 material according to DIN 4102 or a VO material according to UL 94.

Such incombustible plastic material is a thermoplastic moldable or extrudable blend whose base is a polymer selected from among polycarbonates, polyamides, polyethers, polyimides, polyurethanes, polyolefins, polysulfides, polysulfones, vinyl polymers, copolymers and/or mixtures and/or alloys thereof, and at least one inorganic flame retardant compound selected from the group comprising hydrated aluminum oxide, hydrated magnesium oxide, zinc borate, boric acid, inorganic boron compounds and mixtures thereof in amounts of 1 % to 60% and preferably of 20% to 50% by weight with respect to the blend.

Without limitation, polyolefins may include polyethylene and polypropyl, polyolefin copolymers may include polyethylene copolymers such as EVA, EVAL, ethylene acrylate such as ethylene methyl acrylate, ethylene ethyl acrylate, ethylene butyl acrylate, ethylene methacrylate, polyamides may include PA6, PA66 polyamides and the above semiaromatic polyamides, polyethers may include polypheny! ether, possibly with at least one methyl group on the aromatic ring.

According to another preferred embodiment the heat-resistant and incombustible plastic material is also intumescent and consists of a blend having thermoplastic characteristics and comprising one or more thermoplastic polymers contained in said blend in an amount of 30% to 60% by weight and preferably of 35% to 45% by weight, and at least one precursor which is able to generate an acid when exposed to temperatures exceeding 25O ⁰ C.

According to the invention, the thermoplastic polymer is a polymer selected from the group consisting of polyamide, styrene-butadiene-styrene, styrene-isoprene-

styrene, polyether, polyether-polyester, polyether-polystyrene, polyether- polyolefins, polyether-polyamide, polyether-polyimide, polysulfide, polysulfone, polyurethane, ethylene polymer, vinyl polymer e/o copolymer, copolymers and/or mixtures and/or alloys thereof.

According to the invention, usable ethylene polymers include HDPE, LDPE, PE, vinyl polymers or copolymers include EVA, PVAC, PVAL, PAA, ethylene acrylate copolymers such as ethylene methyl acrylate, ethylene ethyl acrylate, ethylene butyl acrylate, ethylene methacrylate, polyamides include PA6, PA66 polyamides, the semiaromatic polyamides are the above described semiaromatic polyamides, polyethers include polyphenyl ethers, polyphenyl ethers with at least one methyl group on the aromatic ring, alone or in combination with polystyrene, polyamide, polypropylene or polyether imide.

Suitably, the vinyl polymer is polyethylene vinyl acetate (EVA) having an acetate content of 20% to 50% by weight, preferably of 25% to 40% by weight or ethylene methyl acrylate, having a methyl acrylate content of 20% to 50% by weight.

Several ethylene and/or vinyl polymers may be used at the same time, including PE (polyethylene) and PVA (polyvinyl acetate): in this case, the acetate content will be related to the total of vinyl polymers in use.

Up to 20% by weight of HDPE or LDPE or a mixture thereof may be added as an adjuvant to obtain a finished product with optimized mechanical properties.

At temperatures above 400 ⁰ C, the acetic group is expelled, thereby leaving an unsaturation, wherefrom cyclization reactions are initiated, which are catalyzed by the presence of mineral acid, and lead to the production of a carbon compound which is stable at high temperatures.

Polyamides also cyclize at temperatures from 300 ⁰ C to 500 ⁰ C, thereby forming a charred structure, and this cyclization reaction is promoted by the presence of strong mineral acid.

The formation of a compact charred structure by polyphenyl ethers, polypheny! ethers having short aliphatic chains on the aromatic ring, alone or in combination with polystyrene, polyamide, or polypropylene is promoted by the presence of a strong mineral acid.

The acid precursor or generating compound is a compound, generally a salt or an ester of a mineral acid, which can decompose at moderate temperatures, e.g. from 250 ⁰ C to 450 ⁰ C, thereby releasing the corresponding acid.

According to the invention, the acid generating compound is a boron compound selected from the group consisting of triisopropyl borate, tri-n-propyl borate, melamine borate, ammonium pentaborate or a phosphorous compound selected from the group consisting of red phosphorous, phosphoric acid esters, such as triaryl phosphates, nitrogenous phosphoric acid compounds or mixtures thereof.

Preferably, the nitrogenous phosphoric acid compounds are melamine phosphate and ammonium phosphate in the polymeric polyphosphate form.

Since ammonium phosphate decomposes at relatively low temperatures, about 100 ⁰ C, which are too low to initiate the cyclization process, a proper charred structure may be only formed by using ammonium polyphosphate, preferably with a chain having a molecular weight of more than 1000 units, which decomposes to phosphate ion and ammonia at temperatures above 350 ⁰ C.

Furthermore, polyphosphate chains, which are scarcely movable in the polymer and substantially insoluble in water, limit migration of the polyphosphate from the inside to the surface, as well as degradation of expansion properties.

Such degradation may be further limited by using ammonium polyphosphate particles pre-coated with a polymer compatible with the base polymers of the heat resistant thermoplastic blend.

An ammonium polyphosphate pre-coated with a formaldehyde melamine-based thermosetting resin is particularly suitable therefor.

Such coated ammonium polyphosphate, which decomposes at temperatures of about 300 ⁰ C, is particularly suitable with polyamides and polyphenyl ether containing blends.

In accordance with another preferred embodiment, the ammonium polyphosphate may be silanized to enhance compatibility with the polymer matrix, thereby promoting cyclization reactions.

The phosphoric acid esters are preferably selected from the group consisting of triphenyl phosphate, diphenyl cresyl phosphate, tricresyl phosphate, diphenyl octyl phosphate, trioctyl phosphate, triethyl phosphate, dimethyl propane phosphate and the same having an aliphatic chain CrC ₄ on the aromatic ring.

According to the invention, the boron compounds are contained in the thermoplastic blend in an amount of 1 % to 30% by weight and preferably of 2% to 15% by weight and the phosphorous compounds in an amount of 1% to 30% by weight.

According to another preferred embodiment, the intumescent thermoplastic blend further comprises at least one expandable inorganic compound, in an amount of 1 % to 50% by weight and preferably of 15% to 35% by weight.

The expandable inorganic compound is selected from the group consisting of expandable graphite, expandable vermiculite, expandable mica, alkaline polysilicate or mixtures thereof.

Expandable graphite is natural graphite, of which it retains the typical "flake" form, in whose lamellar structure an intercalant ion is introduced, by treatment with strong mineral acids in an oxidizing environment. At high temperatures, the intercalant ion reacts with carbon thereby generating a large amount of gas compounds, which open the graphite flakes apart, and produce the typical vermiform shape.

After treatment with acid, graphite may be washed to remove excess acid, which is possibly neutralized by alkalis. Depending on its treatment, graphite may be acid (with free, non intercalant, residual acid), neutral or basic, with alkalis remaining from the neutralization treatment. Once again, in the latter case, expansion is caused by the acid-derived intercalant anion.

Vermiculite and mica are phyllosilicates with water introduced in their lamellar structure as an intercalating compound. Here again, at high temperatures, large amounts of gas are generated, which open the sheets of the lamellar structure apart, thereby creating an expanded vermiform structure (giving the name to vermiculite).

Alkaline polysilicates have a rather complex structure, which is normally represented as xSiO ₂ -yMe ₂ O-zH ₂ O in which XSiO ₂ indicates the acid silica component, VMe ₂ O indicates the basic alkaline metal oxide component, generally lithium, sodium or potassium and zH ₂ O indicates the hydration water. The polysilicate type is defined by the molar or SiO ₂ / Me ₂ O weight ratio SiO ₂ / Me ₂ O, i.e. of the silica component to the alkaline metal oxide component.

The term alkaline polysilicate as used hereafter is meant to indicate a compound as set forth hereinbefore with a molar ratio SiO ₂ / Me ₂ O of 1.5 to 25, preferably of 3 to 6.

The intumescent thermoplastic blend of this invention may further contain hydrated aluminum oxide and/or hydrated magnesium oxide, in amounts of 1 % to 10% by weight and preferably of 1% to 6% by weight.

When heated, both substances release water of crystallization, thereby absorbing large amounts of heat.

Conveniently, all the above polymers and blends may further comprise an inorganic filler selected from the group consisting of long or short glass fibers, clay, kaolinite, feldspar, mica, talc, silica and mixtures thereof in amounts of 1 % to 35% and preferably of 5% to 20% by weight.

In addition to the above components other components may be obviously provided, which are ordinarily used in plastics industry and are known to those skilled in the art, such as UV stabilizers, e.g. carbon black, in amounts of 1 % to 3% by weight, antioxidants, e.g. IRGANOX 1010® (CIBA) in amounts of less than 1 %, crosslinking agents such as peroxides in amounts to 1 %, without departure from the scope of the invention.

According to the invention, the case structure essentially comprises a plastic boxlike container, designated by numeral 1 , which comprises a tray 2 and at least one attachment portion 3, 3', to be anchored to the door or window frame, not shown, by suitable fastening means.

In the embodiment of the figures, the tray 2 has an essentially prismatic shape, with a bottom wall 4 and side walls 5, 6, 7, 8, although many other different shapes may be used without departure from the scope of the invention.

The side walls 5, 6, 7, 8 have an edge 9, 10, 11 , 12 respectively.

Each attachment portion 3, 3' has a longitudinal tab 13, 14 which extends outside of the tray 3 from the edge 10, 12 of at least one of the side walls 5, 7,

substantially orthogonally to the side walls. This tab 13, 14 has means 15, 16 for fastening the case structure to the door or window frame on which it is mounted.

Suitably, the fastening means 15, 16 comprise receptacles 17, 18 for screw fasteners, not shown.

Preferably, for easier mounting, the receptacles 17, 18 include means for centering the case structure on the door or window frame, which comprise pins 19, 20 disposed along the edges of the receptacles 17, 18 and extending outside of the tray 2 from the surface of the tabs 13, 14.

For the lock to be accommodated in the tray 2, at least one of the side walls 5, 7 has fastening means which include a plurality of projections 21 extending from the side walls 5, 7 into the tray 2, each having end portions 22 conformed to hold fast the lock.

To prevent the outer sheets of the door or window frame from bending inwards during handle mounting, the bottom wall 4 of the tray 2 has a number of substantially tubular projections 23, 24, 25, which extend outwards from the tray 2 and define means 26, 27, 28 for locking spacer members D for the outer sheets of the door or window frame.

Suitably, the spacer members D have a prismatic, preferably cylindrical shape, and are made of a heat resistant plastic material as set forth above.

Therefore, no thermal bridges are generated, whereby the door or window complies with applicable standards.

For the case 1 to be stably accommodated within the door or window frame, the side walls 5, 7 have projections 29 extending outside the tray 2 from such side walls 5, 7, each consisting of a sheet wall 30 substantially perpendicular to the

side wall 5, 7, wherefrom it extends, and having an end portion 31 abutting against the inner surfaces of the door or window sheets.

To allow handle mounting, the two opposing side walls 5, 7 of the tray 2 have apertures 32, 33, in registered relationship, for the passage of the handle pin and all necessary fastener means.

The above case structure 1 may be suitably obtained by injection molding of the heat-resistant and/or intumescent thermoplastic material in a single molding step.

According to another aspect, the invention provides a door or window frame, particularly a fire-retardant metal door or window frame having the above lock case structure.

Example 1

A 16 mm, 25 diameters long, corotating twin-screw extruder with a die head (Thermo Prism / Haake), was fed by dosers (Brabender Twin-Screw) with 400 g/h of EVA, 3 melt index, with 40% acetate, 300 g/h of neutral expandable graphite, 300 g/h of melamine borate, 50 g/h of ammonium polyphosphate, 50 g/h of hydrated aluminum oxide, 1 g/h of carbon black. A solid continuous web was thus obtained, which was directly cut by a cutter to obtain 3 - 5 mm diameter granules, adapted for feeding an injection molding press (Negri Bossi).

Samples were die cut from the side wall of the tray so obtained, for testing intumescent properties.

Intumescent properties were determined by measuring the expansion ratio, i.e. the ratio between the final height and the initial height of a 50 mm diameter sample which was placed in a muffle furnace at 45O ⁰ C for 30 minutes.

In such measurements, the sample was placed on the bottom of a steel cylinder of identical diameter. Measurements were carried out both with the sample being

free to expand (free expansion), and with the sample expanding against a 100 g weight placed thereon (expansion under load). The results are reported in Table 1.

Table ϊ 1

Temperature Free expansion ratio Expansion ratio under load

45O ⁰ C 29 14

Examples 2 - 31

Using the extruder and the injection molding press of Example 1 , lock cases were prepared from the blends reported in Tables 2, 3 and 4, and were tested by the measurement system as set forth above. In these tables, the vinyl acetate- containing polymers are conveniently characterized by two numbers, the melt index (Ml), in accordance with ASTM, and the vinyl acetate content in percent. For example, 3/40 indicates a 3 Melt Index and 40 % vinyl acetate.

Table 2

Example 32

Two fire doors, with the intumescent lock case made from formulations 1 , 5, 15 applied thereon in distinct sections, were fire tested for validation according to the procedure of UNI EN 1634-1 standard.

For a predetermined time, depending on the desired classification (30, 60, 120, 180 minutes), the thermocouples on the door had to indicate a temperature increase of less than 180 ⁰ C on the door and of less than 360 ⁰ C on the frame.

Particularly, this had to occur at the thermocouple placed 100 mm from the lock, as required by the above standard.

The doors equipped with the above case lock have exceeded a fire resistance time of 120 minutes. Particularly, the lock case has completely sealed the voids around the lock, thereby effectively insulating the lock so that the thermocouple has sensed a temperature increase of less than 180 ⁰ C after 120 minutes.

The case lock structure of this invention is susceptible of a number of changes and variants, within the inventive concept disclosed in the appended claims. All the details thereof may be replaced by other technically equivalent parts, and the

materials may vary depending on different needs, without departure from the scope of the invention.

While the device and method for making it have been described with particular reference to the accompanying figures, the numerals referred to in the disclosure and claims are only used for the sake of a better intelligibility of the invention and shall not be intended to limit the claimed scope in any manner.