CA2330354A1 - Thermolaminate comprising at least one thermosensitive system - Google Patents

Abstract

Transparent laminates comprising at least one layer comprising: - one or more heat-sensitive systems, the components of which are preferably encapsulated; and - at least one layer substantially impermeable to UV light. thermochromic systems comprise at least one alcohol, one lactone and one ester derivative trapped inside a capsule based on a resin. Laminates have improved UV and oxygen stability. </ SDOAB>

Description

THERMOLAMINATED COMPRISING AT LEAST ONE SYSTEM
THERMOSENSITIVE
DESCRIPTION
Technical area The present invention relates to a transparent laminate comprising one or many heat-sensitive systems, preferably comprising one or more systems thermochromic, preferably with encapsulated components, and provided with preference of a UV light filter.
The present invention also relates to only objects, such as panels display, equipped with such a laminate.
The present invention also relates to new systems.
thermochromic comprising at least 3 components. the three components of said systems are preferably an alcohol, a lactone and an ester derivative; the 3 components being trapped inside a capsule, preferably based on a resin.
The object of the present invention is to improve the life of pigments thermochromic in order, first, to minimize the need for replacement and by the same, reducing costs for the maintenance of objects containing such pigments thermochromic.
In the context of the present invention, the term "laminate" is defined as a number of layer, either a number of different layers, glued or attached from another way to each other; layers, applied by evaporation of solvents, by crushing and by vapor evaporation or otherwise; or mixtures of sleeps and leaves.
In the context of the present invention the term "system" as opposed to term "materials" is defined as a product or composition that works so autonomous between several materials.
State of the art Reversible thermochromic materials are known (for example in the patent US-A-4,028,118) and printing inks prepared from these materials have been applied to different articles in order to build indicators of temperature, ornamental items and clothes and toys that change so reversible or which color development at well-defined temperatures. However, for these commercial products, there is a low demand for materials thermochromic durable with a long life expectancy in external conditions.
The materials discolor quickly due to exposure to light solar long periods of constant heating and repeated tilting. of the research have have been conducted within this technical area, as indicated in the patent US-A-4,425,161, in which an improvement in the speed of the light was achieved by adding chemical modifiers inside the material

-2-thermochromic. Furthermore, US patent US-A-5,281,570 discloses of the research leading to the improvement of long-term stability by a improvement chemical components and chemical composition of the material thermochromic.
Thermochromic pigments are pigments which pass from a state to a other when heated. So, they normally have a color to temperature room, and become transparent when heated, ie they become colorless.
This effect can be used in display panels where the screen shows ia text or other data at room temperature, while this text disappears when the screen is heated. This can be used at an ATM to tell to people that tickets are available when the display panel is heated and when the panel display is cooled, or off, it informs that there are no more tickets available.
Thermochromic pigments are present in the form of microcapsules in as long as coloring compound, and i1 is printed as a composition print on the display screen, preferably on a substrate such as a film polymer which is applied to the heatable back such as copper foil or something thing of similar.
Thermochromic pigments have the disadvantage of being sensitive to light UV and to be sensitive to oxidation in the presence of free oxygen. He was proposed (W0 94/27336) to protect a UV-sensitive material by applying a coat protectress UV protection at the top of the display screen to protect the material sensitive to temperature. In addition, the same document proposes the incorporation of an anti oxidizing with thermoschromic materials and / or with the encapsulating material containing the material thermo-chromic.
However, the addition of additives to the encapsulation material is negative in what concerns the effectiveness of thermochromic materials in expressing their shine, contrast and full color. Such encapsulation causes opacity to the colors and reduced their readability.
Using a UV shield forming part of the screen display, we increases the costs associated with the fact that the UV protective agent ages. So, a diaper UV protective of the laminate of the present invention minimizes costs and product for replacement in a simpler and more efficient way.
Furthermore, JP 7205545 discloses that the use of a material UV reflective on a reversible, heat sensitive screen, said reflective material having a thought less than 50% UV at a wavelength of 350 nm. This means that more 50% of UV light at 350 nm passes through and will cause destructive effects on the thermo layer Chromic.
Although many patents have been issued in connection with screens display thermochromic, such panels have not been obtained to date at a level commercial due to the sensitivity of thermo-chromic materials used and at the resolution of the adjoining technical problem.
Summary of the present invention It has now been surprisingly found that it is possible to solve this problem by means of the present invention, which is characterized in that the thermolaminé

-3-includes at least one layer comprising one or more systems thermosensitive (from preferably thermochromic) and preferably at least one layer substantially impervious to UV light.
It was found that exceptional performance was obtained for the thermolaminates comprising at least one of the new thermochromic systems developed by the Applicant. Thus, the invention applies to laminates transparent comprising one or more thermochromic materials. Another aspect of the present invention relates to heatable display screens comprising at least one of these transparent laminates, as well as in general, to other articles comprising such transparent laminates. Other characteristics of the invention will be obvious from claims accompanying this application.
The laminate of the invention firstly provides physical contact between the material thermosensitive and the protective layer (s).
By means of the present invention, it is possible to increase considerably the duration life of a thermochromic screen and thereby obtain a product acceptable from commercially, avoiding degradation by UV light and blue light visible at low wavelength, as well as degradation by oxidation, all in now the brightness and contrast of the thermochromic data presented on ie a display screen.
In the following, the present invention will be explained further with references to examples of implementation, some of these examples refer to drawings accompanying persons who are only illustrative and who however do not provide any restriction to the present invention.
Brief description of the drawings Figure 1 shows an illustrative example of a transparent laminate according to the present invention;
Figure 2 shows another embodiment of the present invention;
Figure 3 shows another additional embodiment of this invention;
Figure 4 shows a display screen using the present invention; and Figure 5 shows a heat-sensitive laminate according to the present invention.
detailed description In the drawings, the reference numbers used refer to the same type of layer than those used for the construction of the laminate. (I) means a basic substrate consisting for example of a polyester sheet (PET) having a thickness about 250 pm to which a thermochromic print has been applied. The substrate basic can be either transparent, or non-transparent, but is preferably not transparent to form a back layer of the thermochromic layer, and to hide, all optional equipment placed behind the substrate as part of a application. At top of the substrate, there is a layer (3) consisting of a protective material UV, one optical filter, applied. The filter prevents light having a length wave

-4-less than 420 nm to penetrate the layer, and thus reach the layer thermochromic. Said layer has a thickness of about 10 ~ m.
Figure 1 illustrates a basic drawing of a protected thermochromic layer.
In Figure 2, protection has been further improved by adding a movie (4) blocking oxygen, said film was applied on both sides to prevent oxygen to penetrate and reach the thermochromic layer on any side.
Figure 3 illustrates another embodiment in which the layer blocking oxygen has been added between the thermochromic layer (2) and the protective layer UV on the transparent side of the substrate.
Figure 4 shows a display screen (5) including a heating zone (6), on the screen a substrate according to the mode represented in Figure 3 was applied.
The panel display (5) comprises a surface-shaped heating layer (6) heated electrically for heating the thermochromic printing material (2).
Figure 5 is an overview of a thermolaminate according to the invention which comprises in its central part a photosensitive polymer (10) in which is incorporated a thermosensitive system (12), the photosensitive polymer (10) is surrounded by a middle inert (13), itself wrapped by a screen film (14). Said screen film being surrounded by a barrier film (15). The photosensitive polymer (10) is preferably weakly oxidizable and contains antioxidant and photostabilizing compounds as example one polyvinyl alcohol. The inert medium (13) is preferably made up by vacuum.
The film (14) shields from UVA-UVB radiation and can for example be a movie AWARENESS '''M marketed by 3M. The film (15) surrounding the movie screen (I4) forms a barrier to oxygen. It may for example be a CERAMIS'M film.
The thermo-laminate before rolling has an oval shape as shown in the figure 5.
After rolling the thermo-laminate has a flat shape similar to that like represented for example in Figure 4.
The UV protective layer consists of polymers having an agent absorbing them UV, such as the absorbent agent "COURTGUARD UV" and they are often of the type in use in protective sun lotions. Suitable UV screening agents are amines protected (HALS) from benzophenones, benzotriazoles, or combinations of these last.
Other light and UV protective agents are barriers corner, eg reflective barriers that allow the reflection of an angle and not of a other.
Other means are layers which only allow the passage of light polarized.
Photochromic material can also be used to provide bright light.
protection and / or to increase the readability of a display panel equipped with such a the mine.
The oxygen blocking barrier consists of one or more substances following, viz: polyamide resins (NYLON), polyvinylidiene chloride resins (PVDC), hydrolyzed ethylene acetate vinyl resins (EVOH), Si02, AL203, which function all like oxygen scoffers. Even polyester resins resist the permeability of oxygen to some extent. Another blocking material oxygen is metallic aluminum which preferably can be applied on the side back of the substrate when made from a non-material transparent.

- 5 -Other oxygen blocking materials, which are also called "oxygen scavengers "
are available, also in the form of thin films, or as granules which can be included and extruded together with all oxygen tight layers.
Si02, and AL203 can be obtained and used as thin glazed leaves and transparencies with a thickness between 0.5 and 10 pine preferably 1 and 5 pin, and will be laminated on the base substance with the thermochromic layer.
PVDC can be applied as a pure coating, while PET and polyamides are preferably applied as films, whereas a material adhesive is used to attach them to the backing layer. The adhesive used must not not affect a any of the layers, either directly or indirectly through transfer to across any layer.
Whether or not the layers are applied as a coating eg applied as solutions and then dried, or as films, the thinness of the layer resulting is about 0.5 to 10 pin. In addition, the coats can be applied over a side of substrate or both.
The printing mixture, normally a water dispersion of the coloring material thermochromic encapsulated, can be applied between two layers of substrate, such as layers comprising components impervious to UV light and / or materials protecting against oxidation, the aqueous dispersion being hardened between of them layers.
The adhesive agents used to fix the films on either of the substrates is a any adhesive agent which is compatible with a printing mixture, eg the thermochromic material and its encapsulation, which provide adhesion solid and who maintains its properties during heating and radiation of the light like when present in a display screen.
The adhesive agent is preferably selected from the group consisting of adhesives to polyurethane-based, silicone-based adhesives, silicone-based adhesives polyvinyl acetate, and acrylate adhesives, although the choice of adhesive can enormously vary depending on the thermoschromic material used and its encapsulation.
The oxygen permeability is as follows with regard to the above materials mentioned as preferred substances for forming an oxygen blocking layer, viz.
PET 80cm3 / (m2 x days x bar) PVDC - 8 cm3 / (m2 x days x bar), bedding EVOH - 2 cm3 / (m2 x days x bar), extruded in polyethylene Si02, A1Z03 - 0.2 cm '/ (m ~ x days x bar), bedding Polyamide - 8 cm3 / (m2 x days x bar) Al - 0.15 cm3 / mz x days x bar), metallic film

-6-Thermochromic materials can be materials which are optically controlled by heat and, in particular, liquid crystals microencapsulated, polymer dispersed liquid crystal (PDLC) and thermochromic inks based micro encapsulated leuco dyes that can change the absorption of light when heated. PDLC and thermochromic inks based on leuco microencapsulated dyes that can all change light absorption when become heated, are preferred, while leuco-based inks micro dyes encapsulated are the most preferred of all.
According to a particularly preferred embodiment of the invention, the laminated transparencies include one or more heat-sensitive systems, (of preferably one or several thermochromic systems) and also preferentially, a filter of the light UV, characterized in that it comprises at least one layer comprising one or more many heat-sensitive systems and at least one substantially impermeable layer to the UV light.
According to a preferred embodiment of the invention, the systems thermochromic present in the laminates of the invention comprise at least:
- a component A which is an alcohol or a substituted alcohol, preferably a cyclic alcohol or a substituted cyclic alcohol, more preferably an aliphatic alcohol, a phenol or a phenol substituted, more preferably still a biphenol A or a biphenol A
substituted, the substituent preferably being chosen from the group consisting by linear or branched alkyls, preferably lower alkyls linear or branched having del to 5 carbon atoms;
- a component B which is a lactone or a lactone derived from preferably a lactone chosen from the group consisting of spirolactones and by substituted spirolactones, more preferably another Crystal Violet lactone, the substituent being preferably chosen in the group consisting of linear or branched alyls, preferably in the group consisting of linear or branched lower alkyls having from 1 to 5 atoms; and - a component C which is an ester derivative, preferably an acetate of naphthyl or a substituted naphthyl acetate, the substituent being chosen from preferably in the group consisting of linear or branched alkyls, of preferably linear or branched lower alkyls having 1 to 5 atoms of carbon:
said components being placed inside a capsule based on a selected resin of preferably in the group consisting of aminoplast resins; more preferably still in the group of formaldehyde melamine resins.
Resins suitable for the constitution of capsules as well as the mode of preparation such resins are described in American patent US-A-4,888,269, the content is incorporated by reference into the present application.
According to a preferred embodiment of the invention, the system or systems thermochromic (s) include in said capsule:

- from 8 to 20% by weight of component A;
from 2 to 10% by weight of component B; and - from 70 to 90% by weight of component C.
According to a more preferential embodiment of the invention, the systems thermochromics include in said capsule:
- from 11 to 17% of component A;
- from 4 to 6% of component B; and - from 75 to 85% of component C.
Even more preferably, the thermochromic system or systems include in said capsule:
- about 15% of component A;
- about 5% of component B; and - approximately 80% of component C.
Encapsulation of the thermochromic system by a capsule preferably base of melamine is produced according to the procedure explained below.
The melamine-formaldehyde resins (MF) preferably used are base of melamine-formaldehyde are part of the aminoplast family. Those are Contents thermosets obtained by polycondensation of formaldehyde with urea or melamine resulting in the formation of a three-dimensional network. These polymers are very good chemical resistance, high hardness and resistance to light.
The microencapsulation process of the thermochromic components is carried out in oil-in-water emulsion. The hydrophobic base constitutes the internal phase thermochromic. The continuous aqueous phase consists of oligomers of Melamine-formaldehyde also called aminoplast prepolymers.
The reaction begins with a first phase of acid catalysis between the melamine and the formaldehyde. The next step is the crosslinking reaction of the the reaction catalysis at the interface of the aqueous continuous phase and the oily phase, forming a three-dimensional network. The preferential polymerization conditions are a pH
close to 4 and a medium temperature close to 60 degrees Celsius.
The invention will be described in more detail using the following examples.

A laminate with five (5) layers was prepared according to the mode explained below.
A
oxygen barrier is laid down on a white PET film establishing a rear white plan for printing. The oxygen barrier consists of Rayopp RXF films UCB.
It has a thickness of 25 µm and is a bi-oriented polypropylene film with sleeps PVDC on both sides. This film is laminated on PET film using a glue 2pm polyurethane. The white PET film is, as such, not good as oxygen barrier. The PET film has a thickness of 50 µm and, by example, a polyester film Melinex by Dupont.

_ $ _ PET film is printed using a technique printing technique "screen printing "to obtain the appropriate thickness of 20 to 30 ~ m of printing.
summit of printing, another oxygen barrier is laminated using the same glue polyurethane. Finally, on the top of the second oxygen barrier, a UV filter consisting of a 50 µm polyester base and a UV absorbing layer of 2 gym.
The UV absorbing film is sold under the trade name Tinuvin by Ciba-Geigy.
The coating consists of protected amines (HALS) which have the power absorb most of the UV light and convert it to heat.
Other laminated transparent films having UV absorbing properties and protective properties against oxygen have been studied in an accelerator solar Xenotest, 550W / mz, black body at a temperature 45 + 2 ° C, temperature 22 + dryer 2 ° C, having a simulated indoor exposure pre-filter. of the color measurements have were performed using a portable Minolta CM-503i spectrophotometer, measuring at the CIE Lab scale.
The laminate used is a COURTGUARD UV filter and the PET film has been coated on his side bitter using 9 ~ m aluminum foil and the front side of PET
12 pm was coated with 2 µm PVDC. The thermochromic print was a thermo ink chromic Reference SEX62 marketed by the Aimco Company from a acrylate type polymer from Dubois, UV treated and having a 25 thickness pm, at a tipping temperature of 62 ° C. The original color was blue; a comparison was made using only a printed PET film. Three laminated different have been produced, viz: oxygen barriers on both sides +
UV filter;
oxygen barrier only; UV filter only.
The following results reflecting the performance of the thermo-laminate have been obtained:
Durability Protection (hour) None 50 UV 300 filter oxygen barrier 300 UV filter + 800 barrier of oxygen Durability is defined when the thermochromic material reaches ~ E
'' = 15 (according to the CIE scale) A laminate of the type described in Example 1 was prepared, this laminate differs however in what thermochromic printing was a thermochromic ink created by the Aimco company with the following composition: 35% by weight of thermochromic slurry blue marketed by AIMCO WORLD ENTERPRISES Inc. corresponding to an emulsion aqueous containing melamine formaldehyde retaining a tripartite system composed of bisphenol A, Bristol Lactone bristol and 2-naphthyl acetate, in its form liquid in an aqueous base binder.
The thermochromic system having been previously encapsulated according to the method previously described.
The following results were obtained:
Durability Protection (hour) None 50 LTV 300 filter oxygen barrier 300 L1V filter + oxygen barrier 1500 hours In comparison with the thermolaminate of Example 1 in which an ink thermochromic was incorporated, the thermo-laminate of the example 2 who incorporates a thermochromic system according to the invention has stability UV and a barrier effect twice as high.

Claims (27)

1. Transparent laminate comprising one or more heat-sensitive systems (preferably comprising one or more thermochromic systems). 2. Transparent laminate comprising one or more heat-sensitive systems, comprising a UV light filter, characterized in that said laminate includes at least one layer comprising one or more systems thermosensitive (preferably one or more thermochromic systems) the components of which are preferably encapsulated and comprising (preferably) at least one layer substantially impermeable to the LTV light. 3. Transparent laminate according to claim 1 or 2, characterized in that the where the thermochromic systems include at least:
- a component A which is an alcohol or a substituted alcohol, preferably a cyclic alcohol or a cyclic alcohol substituted, more preferably an aliphatic alcohol, a phenol or a substituted phenol, more preferably still a biphenol A or a substituted biphenol A, the substituent being chosen from preferably in the group consisting of linear alkyls or branched, preferably from the group consisting of alkyls linear or branched lower having 1 to 5 carbon atoms;
- a component B which is a lactone or a lactone derived from preferably a lactone chosen from the group consisting of spirolactones and by substituted spirolactones, plus preferably still a Violet Crystal lactone, the substituent being preferably chosen from the group constituted by the akyls linear or branched, preferably in the group consisting of linear or branched lower alkyls having 1 to 5 atoms; and - a component C which is an ester derivative, preferably a naphthyl acetate or a substituted naphthyl acetate, the substituent being preferably chosen from the group consisting of linear or branched alkyls, preferably lower alkyls linear or branched having from 1 to 5 carbon atoms;
in a capsule based on a resin preferably chosen from the group consisting of aminoplast resins; more preferably still in the group consisting of formaldehyde melamine resins. 4 transparent laminate according to claim 3, characterized in that the or the thermochromic systems include in said capsule:
- from 8 to 20% by weight of component A;
- from 2 to 10% by weight of component B; and - from 70 to 90% by weight of component C. 5. Transparent laminate according to claim 4, characterized in that the or the thermochromic systems include in said capsule:

- from 11 to 17% of component A;
- from 4 to 6% of component B; and - from 75 to 85% of component C. 6. Transparent laminate according to claim 5, characterized in that the or the thermochromic systems include in said capsule:

- about 15% of component A;
- about 5% of component B; and about 80% of component C. 7. Transparent laminate according to any one of claims 1 to 6, characterized in that the layer substantially impermeable to UV light prevents the light having a wavelength less than 420 nm to penetrate the layer. 8. Transparent laminate according to claim 7, characterized in that the layer substantially impervious to UV light prevents light having a wavelength less than 410 nm to penetrate the layer. 9. Transparent laminate according to claim 8, characterized in that the layer substantially impervious to UV light prevents light having a wavelength less than 400 nm to penetrate the layer. 10. Transparent laminate according to any one of claims 1 to 9, characterized in that it additionally comprises at least one layer substantially impermeable to gas. 11. Transparent laminate according to one of claims 1 to 10, characterized in what the layer comprising the thermosensitive system (s) (preferably thermochromic), is provided on one side with a layer substantially impermeable to gas, and on its other side, with a substantially layer impervious to UV light as well as with a gas impermeable layer in an arbitrary order. 12. Transparent laminate according to claim 10 or 11, characterized in that the layer substantially impermeable to gas is substantially impermeable oxygen, ozone, carbon dioxide, water, alcohols lower than lower amines and lower amines in the aqueous phase. 13. Transparent laminate according to claim 12, characterized in that the layer substantially impermeable to gas is substantially impermeable to aqueous ammonia, including gaseous ammonia. 14. A transparent laminate according to any one of claims 1 to 13, characterized in that the different layers have substantially the same coefficient thermal expansion. 15. Laminate according to any one of claims 1 to 14, characterized in that the substantially protective layer of UV contains benzophenones, benzotriazones, protected amines, or combinations of these compounds. 16. Laminate according to any of claims 1 to 15, characterized in that that the substantially protective layer of gases includes resins polyprolyamides, polyvinyldiene chloride resins (PVDC), resins ethylene hydrolysed vinyl acetates (EVOH) Al2O3 and / or SiO2. 17. Laminate according to any one of claims 1 to 16, characterized in that that the substantially protective layer of gases includes scavenger oxygen. 18. Laminate according to claim 11, characterized in that the layer substantially protective of gases is placed closest to the layer including the thermosensitive system. 19. Laminate according to claim 11, characterized in that the layer substantially protective of gases includes a coated polymeric substrate with a gas-impermeable layer on one or two sides. 20. Object presenting thermovariable information characterized in that it comprises a substrate having applied to it a laminate according to one or more of the claims 1 to 19. 21. Object presenting thermovariable information characterized in that it comprises a substrate having applied to it a laminate according to one or more of the claims 1 to 19, as well as a heating source. 22. Display panel presenting thermovariable information, characterized in this that it comprises a substrate having applied to it a laminate according to one or more than one of claims 1 to 19. 23. Display panel presenting thermovariable information, characterized in this that it comprises a substrate having applied to it a laminate according to one or several of claims 1 to 19, as well as a heating source. 24. Thermochromic system comprising at least:
- a component A which is an alcohol or a substituted alcohol, preferably a cyclic alcohol or a cyclic alcohol substituted, more preferably an aliphatic alcohol, a phenol or a substituted phenol; more preferably still a biphenol A or a substituted biphenol A, the substituent being chosen from preferably in the group consisting of linear alkyls or branched, preferably from the group consisting of alkyls linear or branched lower having 1 to 5 carbon atoms;
- a component B which is a lactone or a lactone derived from preferably a lactone chosen from the group consisting of spirolactones and by substituted spirolactones, plus preferably still a Violet Crystal lactone, the substituent being preferably chosen from the group constituted by the akyls linear or branched, preferably in the group consisting of linear or branched lower alkyls having 1 to 5 atoms; and - a component C which is an ester derivative, preferably a naphthyl acetate or a substituted naphthyl acetate, the substituent being preferably chosen from the group consisting of linear or branched alkyls, preferably in the group consisting of linear or branched lower alkyls having from 1 to carbon atoms;

said components A, B and C being inside a capsule based on a resin preferably chosen from the group consisting of aminoplast resins;
more preferably still in the group consisting of melamine resins formaldehyde. 25. Thermochromic system according to claim 24 comprising in said capsule:
- from 8 to 20% by weight of component A;
- from 2 to 10% by weight of component B; and - from 70 to 90% by weight of component C. 26. Thermochromic system according to claim 25 comprising in said capsule:
- from 11 to 17% of component A;
- from 4 to 6% of component B; and - from 75 to 85% of component C. 27. A thermochromic system according to claim 26 comprising in said capsule:
- about 15% of component A;
- about 5% of component B; and - approximately 80% of component C.