Method for producing thermal break profiles for doors and windows

Abstract

The present invention refers to a method for producing thermal break profiles for doors and windows, in foamed polyamide 66. Said foamed polymeric material is obtained by extrusion of polyamide 66 (PA66) granules mixed with at least one blowing agent and is characterized in that said blowing agent is selected from: - citric acid and / or citrates; - carbonic acid and / or carbonates; - pyrophosphoric acid and / or pyrophosphates; and in that said blowing agent is added to the polyamide 66 in a percentage comprised between 1 and 15% by weight with respect to the weight of the polyamide 66.

Description

[0001] METHOD FOR PRODUCING THERMAL BREAK PROFILES FOR

[0002] DOORS AND WINDOWS

[0003] DESCRIPTION

[0004] The present invention refers to a method for producing thermal break profiles for doors and windows, in foamed polyamide 66.

[0005] The assembly of aluminium bars with profiles in material of low thermal conductivity reduces the heat exchange between the outside and the inside of a door and window. Said coupling profile constitutes a thermally insulating barrier that allows optimal thermal efficiency of the housing envelope throughout the year, avoiding excessive use of energy to heat or cool the indoor environment.

[0006] The polyamide profiles inside the aluminium bars minimize the thermal conductivity by convection and / or irradiation, consequently increasing the thermal performance of the doors and windows, making them actually more insulating than in the past, achieving the goal of consistently reducing both energy consumption and CO2 emissions connected with said consumption. State of the art

[0007] Currently, the most widely used and widespread thermal break profiles in the door and window sector are mainly in compact polyamide 66 (PA66), thanks to both the excellent mechanical and physical elasticity characteristics of this polymer, and to the fact that it maintains its molecular characteristics over time, with a relatively long life cycle of substantially more than 10 years.

[0008] Thanks also to the use of glass fibre fillers, PA66 has excellent mechanical characteristics, which in fact make this polymer the most suitable plastic material for the assembly of aluminium bars. Research has led both to the definition of profiles with increasingly complex geometries and to the improvement of materials. This has greatly improved performance values over time in terms of thermal conductivity reduction. Over time, the geometries of these profiles for thermal break have evolved considerably: from relatively small and simple outlines to large outlines with tubular sections which, thanks to the presence of air pockets, make it possible to significantly increase the efficiency of the insulation . The evolution of the geometries was then followed by a research phase aimed at developing materials, such as PA66, which significantly improved the thermal performance of the extruded products and thus further reduced the thermal conductivity .

[0009] Material studies then led to the use of foamed materials. It was therefore thought to apply the expansion principles and themes to the PA66 with the aim of creating micro-gas cells internal to the extrudate during the processing phase.

[0010] There are numerous patent documents that describe procedures for carrying out the expansion of a thermoplastic polymer.

[0011] Patent application W02006077395A1 (Zotefoams PLC - Polyamide foams, process to make them and applications thereof) describes the formation of high density foams by impregnating polyamide resins or alloys with inert gas at high pressure and subseguently reducing the containment pressure to allow expansion of the material.

[0012] Patent application JP04356540 (Furukawa Electric Co. Ltd) describes a process for forming a cellular thermoplastic resin by adding an inert gas to the resin under high pressure, heating the resin to a temperature where its semi-crystallization time is 5 minutes or less, and then cooling the resin.

[0013] Patent application JP11080408 (Yamaha Corp.) describes a process in which a resin is expanded by heating in the presence of an inert gas, increasing the pressure until said gas is in a liquid or supercritical state, removing the resin from the pressurized container, heating the resin above the glass transition temperature to cause foaming, and then cooling the resin to stop cell growth.

[0014] Patent application EP0402883 (Du Pont) describes foaming a polyamide resin by extrusion with a blowing agent.

[0015] Patent application WO2011134996 (BASF SE) describes expandable granules, containing a polymer matrix consisting of at least 55% by weight of polyamide and by a blowing agent.

[0016] The journal article "Processing of Polyamide 11 with Supercritical Carbon Dioxide" (Martinache et al., Ind. Eng. Chem. Res. 2001, 40, 5570-5577) describes a method for expanding a polyamide resin using supercritical carbon dioxide as a blowing agent in a batch process in which the temperature is lowered before the pressure is released. Patent application CN1138851 describes flame retardants containing PA66, PA12, glass fibre, polyphenylene sulfide, ferrocene, barium sulphate and hydrazides.

[0017] Patent application CN107903620 describes a method for producing an insulating material comprising the extrusion of a composition comprising polyamide selected from PA6, PA66 and PA1010 and a blowing agent selected from a list comprising sodium carbonate and citric acid.

[0018] Aim of the invention

[0019] The aim of the invention is to obtain the best possible combination between the values of thermal transmittance [W / mK] and the mechanical performance of the products, in relation to the regulatory needs and the specific needs of the reference market.

[0020] In fact, not only do the mandatory values required by regulations at the individual national level vary in the event of renovations (and indeed, they are binding for entitlement to tax benefits and deductions provided), but also the technical needs of the individual customers may be different, based on the project and the specific work, during the evaluation and implementation phase. In other words, this line of research has been stimulated both by the presence of different regulations at the international level, and above all by the requests of the customers who, based on the specific project, need different performance values. Particular attention is paid to obtaining the best possible thermal insulation combined with the necessary mechanical performance of systems for doors and windows.

[0021] The rationale pursued by the legislator, which has now entered into contemporary economic and social paradigms, is to reduce CO2 emissions as much as possible, favouring greater environmental sustainability of the production activities. Furthermore, at an industrial and production level, the need to maintain high performance levels from a mechanical point of view cannot be neglected or considered as secondary, in order to guarantee the durability and safety over time of the installed products.

[0022] The aim of the present invention is therefore to further improve said profiles for thermal break, in order to obtain the best possible combination between thermal insulation and the mechanical resistance of the doors and windows. The aforementioned and other purposes, as will become clear hereinafter, are achieved at least in part by a method, according to claim 1, for producing thermal break profiles, in foamed polymeric material.

[0023] Said method provides for mixing granules of a thermoplastic polymer with granules of blowing agents, followed by melting said granules and by extruding said thermal break profiles, wherein said thermoplastic polymer is polyamide 66 (PA66), and is characterized in that said blowing agents comprise the following families of chemical compounds: citric acid and / or citrates; carbonic acid and / or carbonates; pyrophosphoric acid and / or pyrophosphates; said blowing agents being added to PA66 in a percentage comprised between 1 and 15% by weight with respect to the weight of the polymer.

[0024] Preferred embodiments and non-trivial variants of the present invention form the subject matter of the dependent claims.

[0025] One aspect of the invention is represented by the fact that the blowing agent is in granules.

[0026] One aspect of the invention is represented by the fact that the blowing agent is selected from sodium bicarbonate, disodium dihydrogen pyrophosphate and potassium pyrophosphate, preferably disodium dihydrogen pyrophosphate.

[0027] One aspect of the invention is represented by the fact that the disodium dihydrogen pyrophosphate is added to the polyamide 66 in a percentage comprised between 7 and 13% by weight with respect to the weight of the polyamide 66, preferably between 8 and 12%.

[0028] One aspect of the invention is represented by the fact that the extrusion is carried out at a temperature comprised between 240° and 280°C, preferably between 250 and 270°C; at a speed comprised between 0.8 and 1.2 m / min, preferably about 1 m / min; and at a pressure comprised between 9 and 11 bar, preferably about 10 bar.

[0029] One aspect of the invention is represented by the fact that the foamed polymeric material contains glass fibre and, in particular, by the fact that said glass fibre is present in an amount comprised between 22% and 28% by weight with respect to the weight of the foamed polymeric material, preferably of about 25%.

[0030] One aspect of the invention is represented by the fact that the foamed polymeric material does not contain sulphides and, preferably, does not contain polyphenylene sulphide.

[0031] One aspect of the invention is represented by the fact that the foamed polymeric material does not contain blowing agents and, preferably, does not contain ferrocene and / or barium sulphate.

[0032] One aspect of the invention is represented by the fact that said foamed polymeric material does not contain hydrazides.

[0033] One aspect of the invention is represented by the fact that said foamed polymeric material does not contain polyamide 12 (PA12).

[0034] One aspect of the invention is represented by the fact that said foamed polymeric material consists of polyamide 66, glass fibre and blowing agent, i.e. no other components are present.

[0035] A further aspect of the present invention is represented by the thermal break profiles for doors and windows obtainable by the method according to the present invention.

[0036] All appended claims form an integral part of the present disclosure.

[0037] Advantages

[0038] From an ecological point of view, the invention has the following advantages: better thermal insulation resulting in less energy use for heating and cooling; lower consumption of polymeric material for the production of the extrudates; lower weight of the doors and windows, therefore lower consumption for the transport of the same; less amount of polymer to be recycled at the end of the life of the door and window.

[0039] It will be immediately obvious that countless variations and modifications (for example relating to manufacturing procedures and process parameters with equivalent functions) can be made to what has been described without departing from the field of protection of the invention, as appears from the appended claims.

[0040] Detailed description of an exemplary preferred embodiment

[0041] The present invention will be better described by a preferred embodiment, provided by way of nonlimiting example, with reference to the accompanying drawings, in which:

[0042] Fig. 1 shows the diagram of an extrusion plant for the production of profiles according to the invention;

[0043] Fig. 2 shows the profiles obtained with the method according to the invention;

[0044] Figs. 3(a, b, c) show the structure formulas of expanders used to produce the profiles according to the invention.

[0045] With reference to Fig. 1, with (1) a production line is indicated, which comprises: a first extrusion zone (2); a second forming zone (3); a third cooling zone (4); an extractor (5); a cutter (6).

[0046] In said first extrusion zone (2) there is a heating cylinder (2a) inside which, depending on the models, there is: a single rotating screw (2b) (single-screw extruder); two interpenetrating screws (not depicted) (twin-screw extruder) that can rotate in a concordant or discordant direction.

[0047] The heating cylinder (2a) of the extruder is fed by a loading hopper (7) preceded by a dispenser (not depicted), into which the granules of the polymer and the expander with which a profile (8) is produced are poured.

[0048] Said profile (8), which is formed when passing through a die (9), is subseguently cooled in the third cooling zone (4), where it is remodelled by passing through special remodelling plates (4a).

[0049] The profile (8), completed and cooled, passes through the extractor (5) and is cut to size by the cutter (6).

[0050] Various endothermic chemical expanders have been used and tested in the research because, compared to the exothermic ones, they are easier to handle during processing, are better suited to production and commonly used extruders and, above all, because the decomposition of these agents produces gases that are neutral to health and the environment. In addition, they do not leave residues in the final product that would compromise its recycling or reuse.

[0051] The expansion process leads to the formation of gas bubbles between the polymer chains. Said gas is an excellent thermal insulator, which significantly increases the thermal insulation of the profile (8).

[0052] Research phases

[0053] The research has focused on identifying a blowing agent that allows, during the extrusion phase, an adequate expansion of the polymer with the objective of reducing the thermal transmittance values.

[0054] The results obtained made it possible to achieve an excellent thermal transmittance level between 0.130 and 0.140 W / mK, a value well below the table value (standard value for foamed polyamide) which stands at around 0.210 W / mK, as shown in the following Tab. 4.

[0055] In Fig. 2 profiles obtained with the described method are shown, in which the structure with microcavities formed by the expansion of the gas can be noted.

[0056] Tested blowing agents

[0057] Various endothermic blowing agents of different chemical nature were tested.

[0058] According to a preferred embodiment, said blowing agents comprise the following families, the structure formulas of which are shown in Fig. 3: citric acid and / or citrates (Fig. 3a); carbonic acid and / or carbonates (Fig. 3b); pyrophosphoric acid and / or pyrophosphates (Fig. 3c).

[0059] In a range of use varying from 1 to 15% by weight with respect to the weight of the polyamide used, said percentage being chosen, using known procedures, as a function of the degree of expansion desired.

[0060] During the extrusion phase, said blowing agents undergo a decomposition reaction releasing gases, such as carbon dioxide and water vapour, which cause the formation of empty microcells in the polymer, in this case PA66.

[0061] The polymer, by cooling at the exit of the die (9), maintains the cavities formed. This porous nature leads to a substantial increase in the insulating capacities of the polyamide 66 and therefore of the finished product, once installed in the fixture. The reduction in the density of the material also has the effect of reducing its weight.

[0062] The blowing agents tested are in granules and have been mixed, according to the instructions provided by the manufacturers, with the PA66 granules and then loaded into the extrusion hopper (7).

[0063] Single-screw extruders were used for the research. The material used has been predehumidified to avoid excessive production of water vapour during processing.

[0064] Several extrusion tests were carried out to identify the optimal machine parameters in order to have constant, stable and continuous processing, with the required dimensions and aesthetics, according to the company's quality standards.

[0065] The optimal temperatures of the extruder in order to have the best expansion of the agent were identified, concentrating the decomposition only in the last part of the extrusion zone (2), so as to avoid gas leaks, and thus compromise the stability of the extrusion.

[0066] The tests were carried out with multiple moulds on different extrusion lines available in the company. The important thing about this project / study was the use of existing matrices in the company without the need to modify or build new equipment.

[0067] The optimal blowing agent for the production line was identified and the process parameters listed above were optimized. The stability of the process was also evaluated by carrying out a production on several working shifts over 24 hours.

[0068] Different percentages (1-10%) of the various expanders were then tested, obtaining satisfactory results both in terms of density and weight decrease. The range of decrease in density, in the highest performing test, was 20^-25% while the decrease in weight was up to 20%.

[0069] Tests performed

[0070] First test - carried out with citric acid at 10% by weight with respect to the PA66 material, with the following parameters: extrusion temperature 250°C to 320°C; speed: 2.5 m / min; pressure: 15 bar.

[0071] A representative profile with a width of 24 mm was made. The test is not satisfactory because the machine does not have a continuous extrusion but there are pressure fluctuations that result in seizures and stops. Second test - carried out with sodium bicarbonate at 15% by weight with respect to the PA66 material, with the following parameters: extrusion temperature 260°C to 320°C; speed: 2.5 m / min; pressure: 15 bar.

[0072] A representative profile with a width of 24 mm was made. The test is not satisfactory because the machine does not have a continuous extrusion but there are pressure fluctuations that result in seizures and stops. Compared to the first test, however, there is an increased stability.

[0073] Third test - carried out with potassium pyrophosphate at 15% by weight with respect to the PA66 material, with the following parameters: extrusion temperature 260°C to 320°C; speed: 2.5 m / min; pressure: 15 bar.

[0074] A representative profile with a width of 24 mm was made. The test is satisfactory because the machine has a continuous extrusion, there are no pressure fluctuations or seizures and stops. However, an excessive expansion is noted, i.e. the weight loss compared to an unfoamed standard is higher than 35%.

[0075] Fourth test - carried out with potassium pyrophosphate at 10% by weight with respect to the PA66 material, with the following parameters: extrusion temperature 270°C to 325°C; speed: 2.5 m / min; pressure: 15 bar.

[0076] A representative profile with a width of 24 mm was made. The test is satisfactory because the machine has a continuous extrusion, there are no pressure fluctuations or seizures and stops. The expansion is acceptable, i.e. the weight loss compared to an unfoamed standard is 25%.

[0077] Fifth test - carried out with disodium dihydrogen pyrophosphate at 8% by weight with respect to the PA66 material, with the following parameters: extrusion temperature 250°C speed: 1 m / min pressure: 10 bar

[0078] A representative profile of 250 x 10 x 2 mm was made. The test is positive, one has an extruded sample with a final density of 1.10 g / cm3on average, compared to the unfoamed polyamide standard of 1.30 g / cm3.

[0079] Sixth test - carried out with disodium dihydrogen pyrophosphate at 10% by weight with respect to the PA66 material, with the following parameters: extrusion temperature 260°C speed: 1 m / min pressure: 10 bar

[0080] A representative profile of 250 x 10 x 2 mm was made. The test is positive, one has an extruded sample with a final density of 0.95 g / cm3on average, compared to the unfoamed polyamide standard of 1.30 g / cm3.

[0081] The samples of this test were analysed by the IFT Rosenheim laboratory with the result of a thermal transmittance of 0.21 W / mK. Seventh test - carried out with disodium dihydrogen pyrophosphate at 12% by weight with respect to the PA66 material, with the following parameters: extrusion temperature 270°C speed: 1 m / min pressure: 10 bar

[0082] A representative profile of 250 x 10 x 2 mm was made. The test is positive, one has an extruded sample with a final density of 0.85 g / cm3on average. Compared to the unfoamed polyamide standard of 1.30 g / cm3.

[0083] The samples of this test were analysed by the Certimac laboratory with the result of a thermal transmittance of 0.15 W / mK. Results

[0084] The thermal lambda was measured of the extruded profile with the best characteristics among the first four tests (i.e. that obtained during the fourth test) obtaining a decrease by more than 30% compared to that of the same profile, but made with more compact PA66. The following mechanical properties were also detected in order to check if the creation of cavities in the material weakened its structure: resilience; - hardness; tensile strength.

[0085] Table 1, below, reports the determination of the specific heat by MDSC measurement MDSC (Modulated Differential Scanning Calorimetry) and thermal conductivity by LFA (LASER Flash Analysis) in the temperature range [+10, +30] °C.

[0086] Table 2, below, reports the bending mechanical properties according to EN ISO 178:2019 Method A.

[0087] Table 3, below, reports the tensile mechanical properties according to EN ISO 527-4 / 1B / 2:2021.

[0088] Tables 1, 2 and 3

[0089]

[0090] Table 4, below, reports the comparison between standard PA66 (compact polymer), conventional foamed PA66 and foamed PA66 according to the fourth test. In all cases the polymer was reinforced with 25% glass fibre.

[0091] Mechanical and thermal characteristics

[0092] Physical characteristics ofthe polymer

[0093] Tab. 4

[0094] Table 5, below, reports the density and transmittance values of the foamed polymeric materials obtained in the sixth and seventh tests, as well as the tensile and flexural elastic modulus values of the polymeric material of the sixth test, compared with those known from the standard PA66. Table 5

[0095] Conclusions

[0096] The values obtained from the mechanical tests are comparable to those of the extruded profile in compact polyamide; the values are obviously lower but included in the tolerance range allowed.

[0097] The lower lambda value of the profile leads to an improvement in the thermal insulation of the door and window. The insulating bar therefore allows a reduced installation depth while maintaining the same Uf value (transmittance value) , or alternatively an improved Uf value with the same installation depth. From the tests carried out, it was possible to identify percentages and functional parameters that allow the production of polyamide profiles for thermal break with improved properties in terms of thermal profile and insulation of the fixture and, in particular, with a lower thermal transmittance value. Preferred embodiments of the invention have been described. Modifications and variants, functionally equivalent to the previous ones, which fall within the field of protection of the invention, as highlighted in the appended claims, will be evident to the person skilled in the art.

Claims

CLAIMS1. Method for producing thermal break profiles for doors and windows, in foamed polymeric material obtained by extrusion of polyamide 66 (PA66) granules mixed with at least one blowing agent, characterized in that said blowing agent is selected from: a.citric acid and / or citrates; b.carbonic acid and / or carbonates; c.pyrophosphoric acid and / or pyrophosphates . and in that said blowing agent is added to the polyamide 66 in a percentage comprised between 1 and 15% by weight with respect to the weight of the polyamide 66.

2. Method for producing thermal break profiles for doors and windows, according to claim 1, characterized in that said blowing agent is in granules.

3. Method for producing thermal break profiles for doors and windows, according to any one of the preceding claims, characterized in that said blowing agent is selected from sodium bicarbonate, disodium dihydrogen pyrophosphate and potassium pyrophosphate.

4. Method for producing thermal break profiles for doors and windows, according to any one of the preceding claims, characterized in that said blowing agent is disodium dihydrogen pyrophosphate.

5. Method for producing thermal break profiles for doors and windows, according to any one of the preceding claims, characterized in that said disodium dihydrogen pyrophosphate is added to the polyamide 66 in a percentage comprised between 7 and 13% by weight with respect to the weight of the polyamide 66, preferably between 8 and 12%.

6. Method for producing thermal break profiles for doors and windows, according to claim 4 or 5, characterized in that the extrusion is carried out at a temperature comprised between 240° and 280°C, preferably between 250 and 270°C; at a speed comprised between 0.8 and 1.2 m / min, preferably about 1 m / min; and at a pressure comprised between 9 and 11 bar, preferably about 10 bar.

7. Method for producing thermal break profiles for doors and windows, according to any one of the preceding claims, characterized in thatsaid foamed polymeric material contains glass fibre.

8. Method for producing thermal break profiles for doors and windows, according to claim 6, characterized in that said glass fibre is present in an amount comprised between 22% and 28% by weight with respect to the weight of the foamed polymeric material, preferably of about 25%.

9. Method for producing thermal break profiles for doors and windows, according to any one of the preceding claims, characterized in that said foamed polymeric material does not contain sulphides and, preferably, does not contain polyphenylene sulphide.

10. Method for producing thermal break profiles for doors and windows, according to any one of the preceding claims, characterized in that said foamed polymeric material does not contain blowing agents and, preferably, does not contain ferrocene and / or barium sulphate.

11. Method for producing thermal break profiles for doors and windows, according to any one of the preceding claims, characterized in that said foamed polymeric material does notcontain hydrazides.

12. Method for producing thermal break profiles for doors and windows, according to any one of the preceding claims, characterized in that said foamed polymeric material does not contain polyamide 12 (PA12).

13. Method for producing thermal break profiles for doors and windows, according to any one of the preceding claims, characterized in that said foamed polymeric material consists of polyamide 66, glass fibre and blowing agent.

14. Method for producing thermal break profiles for doors and windows, according to any one of the preceding claims, characterized in that it provides for a use of potassium pyrophosphate at 10% by weight with respect to polyamide 66, with the following extrusion parameters: temperature: 270°C to 325°C; speed: 2.5 m / min; pressure: 15 bar.

15. Method for producing thermal break profiles for doors and windows, according to any one of the preceding claims, characterized in that it provides for the use of potassium pyrophosphate at 15% by weight with respect topolyamide 66, with the following extrusion parameters : temperature: 260°C to 320°C; speed: 2.5 m / min; pressure: 15 bar.

16. Method for producing thermal break profiles for doors and windows, according to any one of the preceding claims, characterized in that it provides for the use of sodium bicarbonate at 15% by weight with respect to polyamide 66, with the following extrusion parameters : temperature: 260°C to 320°C; speed: 2.5 m / min; pressure: 15 bar.

17. Method for producing thermal break profiles for doors and windows, according to any one of the preceding claims, characterized in that it provides for the use of citric acid at 10% by weight with respect to polyamide 66, with the following extrusion parameters: temperature: 250°C to 320°C; speed: 2.5 m / min; pressure: 15 bar.

18. Method for producing thermal breakprofiles for doors and windows, according to any one of the preceding claims, characterized in that it provides for the use of disodium dihydrogen pyrophosphate at 8% by weight with respect to polyamide 66, with the following extrusion parameters: temperature 250°C; speed: 1 m / min; pressure: 10 bar.

19. Method for producing thermal break profiles for doors and windows, according to any one of the preceding claims, characterized in that it provides for the use of disodium dihydrogen pyrophosphate at 10% by weight with respect to polyamide 66, with the following extrusion parameters: temperature 260°C; speed: 1 m / min; pressure: 10 bar.

20. Method for producing thermal break profiles for doors and windows, according to any one of the preceding claims, characterized in that it provides for the use of disodium dihydrogen pyrophosphate at 12% by weight with respect to polyamide 66, with the followingextrusion parameters: temperature 270°C; speed: 1 m / min; pressure: 10 bar.

21. Thermal break profiles for doors and windows, obtainable by the method according to any one of the preceding claims.

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