CN111443412A - High retro-reflection microprism reflective film and preparation method thereof - Google Patents
High retro-reflection microprism reflective film and preparation method thereof Download PDFInfo
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Abstract
The invention relates to the field of reflective films, in particular to a high retro-reflection microprism reflective film and a preparation method thereof. The invention provides a high retro-reflection microprism reflective film and a preparation method thereof, aiming at solving the problem that the brightness of the existing reflective film is obviously reduced after hot sewing is finished. The high retro-reflective micro-prism reflective membrane sequentially comprises a focusing reflective layer, a link transition layer, a reflective unit layer and a weather-resistant surface membrane layer from bottom to top. The highly retroreflective microprismatic reflective film does not include a heat seal layer. According to the high retro-reflection microprism reflective film provided by the invention, after the reflective unit layer is attached to the link transition layer, the brightness is reduced little, namely, the brightness loss is low, and after a high-temperature high-humidity test, the bonding strength of the reflective unit layer and the link transition layer is improved.
Description
Technical Field
The invention relates to the field of reflective films, in particular to a micro-prism retro-reflective product and a preparation method thereof, and particularly relates to a high retro-reflective micro-prism reflective film and a preparation method thereof.
Background
Retroreflection is the reflection of light back from the opposite direction near the incident light, which is maintained when the direction of the incident light is varied over a wide range. Retroreflective sheeting is a retroreflective material that has been made into films for direct application.
The reflective film can be classified into a glass bead type and a microprism type according to a retro-reflection principle. The theoretical reflecting rate of the glass bead type reflecting film can only reach about 30 percent due to the reasons of high reflecting loss, low utilization rate of effective reflecting areas, poor reflecting uniformity and the like. The microprism type reflective film adopts the design of densely arranged triangular pyramid microprisms, and has greatly improved light utilization rate, light reflecting performance, light reflecting uniformity and the like compared with a glass microsphere reflective film, and the theoretical light reflecting achievement rate can reach about 70%.
In the process of manufacturing the reflective film, the reflective semi-finished product is involved. The semi-finished product of the reflection of light that the glass microballon reflective membrane corresponds is called planting pearl semi-finished product, and the semi-finished product of reflection of light that the microprism reflective membrane corresponds is called microprism semi-finished product. After the two types of reflective films are manufactured into the reflective semi-finished product, a closed air layer is formed through a hot sewing process. In the hot sewing process, a hot-sewing film is required to be matched with a special-shaped embossing roller, and hot melt adhesive on the hot-sewing film is instantly melted into high molecular fluid to be adhered to a reflective semi-finished product through ultrasonic welding or a heat conduction technology to form the sewing reflective film.
Generally, in the process of welding or heat conduction stitching, different embossing roller designs are adopted, the shapes of sealed air layers obtained by welding are different, embossing rollers have a rhombic design, a curvilinear quadrilateral design, a hexagonal design and the like, however, no matter which embossing roller design is adopted, as long as the process of using a stitching film for heat stitching exists, in the stitching process, part of hot melt adhesive on the stitching film is melted into adhesive layer gaps between high polymer fluid and micro prisms or glass beads for filling and bonding, so that a certain part of micro prism reflecting units or glass bead reflecting units inevitably lose the reflecting property due to the filling of the hot melt adhesive, and generally, the reduction of the reflecting property can reach a difference of about 30% of the brightness before stitching, and finally, the brightness of a finished product of the reflecting film is reduced greatly. Generally speaking, before and after hot stitching, the semi-finished product of the glass beads and the microprism reflective film loses about 30% of reflective brightness.
Disclosure of Invention
The invention provides a high retro-reflection microprism reflective film and a preparation method thereof, aiming at solving the problem that the brightness of the existing reflective film is obviously reduced after hot sewing is finished.
In the production process of the existing reflective film, after the reflective semi-finished product is subjected to hot sewing treatment, due to the fact that the hot melt adhesive on the sewing film fills part of reflective units, the reflective brightness of the filled part is lost, and the brightness of the reflective film can be lost by about 30% before and after hot sewing. The high retro-reflection microprism reflective film provided by the invention is used for carrying out lamination replacement on the traditional hot sewing film process route, and is matched with the focusing reflective layer, so that the brightness loss of a semi-finished reflective product in the process of preparing a reflective film finished product is reduced, and the high retro-reflection characteristic is realized.
In order to solve the technical problems, the invention provides the following technical scheme:
the invention provides a high retro-reflection microprism reflective membrane which sequentially comprises a focusing reflective layer, a link transition layer, a reflective unit layer and a weather-resistant surface membrane layer from bottom to top.
The highly retroreflective microprismatic reflective film does not include a heat seal layer.
Further, the reflective membrane includes the four layers, and from the bottom up is in proper order for realizing the focus reflection stratum that stray transmission light cycle reflection utilized, realizes that focus reflection stratum and reflection of light unit layer adhesion become a whole, realizes the linking transition layer of stray transmission light cycle reflection smooth transition, realizes the retro-reflective reflection of light unit layer with most incident light, realizes the resistant time surface film layer of permanent weatherability.
Furthermore, the focusing reflection layer comprises a reflection substrate layer, a focusing layer is arranged on the upper surface of the reflection substrate layer, and a metal coating is arranged on the focusing layer; the focusing layer comprises a plurality of concave focusing reflecting lenses.
Further, the focusing layer is composed of a plurality of concave focusing reflecting lenses.
Further, the outer contour of the concave focusing reflection lens is a regular hexagon.
Furthermore, a metal coating is arranged on the focusing layer, and the metal coating is an aluminum coating. The aluminum plating may also be referred to as aluminized layer.
Furthermore, the concave focusing reflection lens is formed by coating and micro-copying the upper surface of the reflection substrate layer, the reflection substrate mainly plays a bearing role, so that the concave focusing reflection lens can be smoothly formed on the upper surface of the reflection substrate, and the concave focusing reflection lens is designed in a special structure so as to meet the requirement of cyclic reflection utilization of stray transmission light to the maximum extent.
Further, the thickness of the focusing reflection layer ranges from 5 to 125 μm.
Further, the thickness of the focusing reflection layer ranges from 10 to 75 μm.
Further, the thickness range of the focusing reflecting layer is 25-50 μm.
The thickness of the focusing reflecting layer is the sum of the heights of the reflecting base material layer, the focusing layer and the metal coating layer.
Further, the material of the reflective substrate layer is selected from one of polyethylene terephthalate (PET), polymethyl methacrylate (PMMA), Polycarbonate (PC), polyvinyl chloride (PVC), or polytriacetic acid fiber (TAC).
Furthermore, the reflective substrate layer (reflective substrate for short) is divided into an upper surface and a lower surface, the upper surface of the reflective substrate is a smooth surface layer, in order to improve the adhesion performance of the upper surface of the reflective substrate to the concave focusing reflective lens, corona treatment or off-line Primer coating (Primer) treatment is generally performed on the upper surface in advance, and the lower surface of the reflective substrate layer is a matte surface.
Further, in the preparation process, the concave focusing reflection lens is formed after the focusing coating liquid is solidified. The focusing coating liquid comprises 40% of oxygen-containing functional group acrylic oligomer, 30% of nitrogen-containing functional group acrylic oligomer, 29.49% of reactive diluent, 0.5% of photoinitiator and 0.01% of flatting agent. The acrylic oligomer containing oxygen functional groups is selected from epoxy acrylate oligomer, the acrylic oligomer containing nitrogen functional groups is selected from aliphatic urethane (methyl) acrylate, the reactive diluent is pentaerythritol tetraacrylate, the photoinitiator is 2-hydroxy-2-methyl-1-phenyl-1-acetone (1173 for short) and the leveling agent is selected from polyether modified polydimethylsiloxane. The concave focusing reflecting lens is prepared from the focusing coating liquid through UV coating, micro-replication and UV curing processes, and then vacuum aluminizing is carried out on the surface of the focusing layer on the concave focusing reflecting lens in a vacuum aluminizing mode to obtain an aluminum coating.
Furthermore, the depths of the concave cambered surfaces of the concave focusing reflecting lenses are the same or different.
Furthermore, the outer contour of the concave focusing reflection lens is a regular hexagon. The regular hexagonal profile is chosen because the concave lens of this design is the highest in void fill ratio, fully performs the role of structural reflection, and is supplemented by aluminized reflection for structural reflection deficiency.
Furthermore, the concave focusing reflection lens (concave focusing lens for short) is composed of a concave cambered surface with the top outline selected from a regular hexagon pattern with high gap filling rate and matched with different depths.
Furthermore, the side length of the regular hexagon outline at the top of the concave focusing lens is 2-50 μm.
Furthermore, the side length of the regular hexagon outline at the top of the concave focusing lens is 6-35 μm.
Furthermore, the side length of the regular hexagon outline at the top of the concave focusing lens is 12-25 μm.
Further, the width of the gap between the top regular hexagon outlines of the concave focusing lens (namely, the distance between the sides of the adjacent regular hexagons) is 0.2-5 μm.
Further, the width of the gap between the top regular hexagonal profiles of the concave focusing lens is 0.5-3 μm.
Further, the width of the gap between the top regular hexagonal profiles of the concave focusing lens is 0.8-1.5 μm.
Furthermore, the depth of the concave cambered surface of the concave focusing lens is 2-25 μm.
Furthermore, the depth of the concave cambered surface of the concave focusing lens is 8-20 μm.
Furthermore, the depth of the concave cambered surface of the concave focusing lens is 12-15 μm.
Further, the link transition layer sequentially comprises an upper adhesive layer, a supporting layer and a lower adhesive layer from top to bottom, and the upper adhesive layer and the lower adhesive layer are collectively called as an adhesive layer. The linking transition layer is also referred to as double-sided tape.
Further, the link transition layer is a prepared delayed acrylic transparent double-sided tape, the delayed acrylic double-sided tape is obtained by reacting acrylate, methacrylate and a delayed crosslinking agent through a UV curing process, and the refractive index of the link transition layer is n 1.
Further, the thickness of the link transition layer ranges from 2 to 20 μm.
Further, the thickness of the link transition layer ranges from 5 to 15 μm.
Further, the thickness of the link transition layer ranges from 8 to 12 μm.
Furthermore, the raw materials of the adhesive layer comprise acrylate, methacrylate and a delayed crosslinking agent.
Further, the acrylate accounts for 20-79% of the formula for preparing the double-sided tape, preferably 35-64% of the formula, and more preferably 39-55% of the formula.
Further, the methacrylate system accounts for 20-79% of the formula for preparing the double-sided tape, preferably 35-64% of the formula, and more preferably 44.5-60% of the formula.
Further, the mass percentage range of the delayed crosslinking agent in the formula for preparing the double-sided tape is 0.1-1.5%, preferably, the mass percentage range is 0.3-1.2%, and more preferably, the mass percentage range is 0.5-1%.
Further, in the preparation process, the raw materials of the adhesive layer are firstly prepared into glue, and the glue comprises 20-79% of acrylic ester, 20-79% of methacrylate and 0.1-1.5% of delayed crosslinking agent; the percentage is mass percentage.
Further, the glue comprises 35% -64% of acrylate, 35% -64% of methacrylate and 0.3% -1.2% of delayed cross-linking agent; the percentage is mass percentage.
Further, the glue comprises 39% -55% of acrylate, 44.5% -60% of methacrylate and 0.5% -1% of delayed cross-linking agent; the percentage is mass percentage.
Further, the acrylate is selected from one or a mixture of at least two of acrylate, hydroxyl acrylate, isobutyl acrylate, n-butyl acrylate, n-octyl acrylate or hydroxyethyl acrylate.
Further, the methacrylate is selected from one or a mixture of at least two of n-butyl methacrylate, allyl methacrylate, ureido methacrylate and benzyl methacrylate.
Furthermore, the delayed crosslinking agent has the function of continuously increasing the adhesive property with the continuous increase of time on the basis of ensuring the adhesive shaping of the double-sided adhesive tape after the double-sided adhesive tape is shaped. The purpose of doing so is that the integrality of upper strata reflection of light unit structure is guaranteed to furthest, avoids the sticky tape to lead to too yielding and make partial reflection of light unit fill and reflect light inefficacy for the too soft, and another is that promote the bonding fastness of linking transition layer with reflection of light unit layer and focus reflecting layer.
Further, the delayed crosslinking agent includes a photosensitive crosslinking agent and a thermosensitive crosslinking agent.
Furthermore, the photosensitive cross-linking agent immediately provides structural shaping for the adhesive tape during the molding of the adhesive tape, and the thermosensitive cross-linking agent continuously provides a cross-linking effect after the adhesive tape is shaped.
Further, the photosensitive cross-linking agent is selected from one of 4-phenylbenzophenone, methyl o-benzoylbenzoate, benzoin dimethyl ether, 1-hydroxy-cyclohexyl-phenyl ketone and ethyl 2,4, 6-trimethylbenzoylphosphonate.
Further, the thermosensitive cross-linking agent is selected from one of trimethylolpropane trimethacrylate, blocked isocyanate, aziridine modified isocyanate and water-based isocyanate.
Further, the mass ratio of the photosensitive cross-linking agent to the thermosensitive cross-linking agent is 0.1-1.5: 1. 0.1-1.5:1 can be abbreviated as 0.1-1.5.
Further, the mass ratio of the photosensitive cross-linking agent to the thermosensitive cross-linking agent ranges from 0.3 to 1: 1.
Further, the mass ratio of the photosensitive cross-linking agent to the thermosensitive cross-linking agent ranges from 0.5 to 0.8: 1.
Further, the reflecting unit layer comprises a substrate layer and a reflecting layer, and the reflecting layer is arranged on the lower surface of the substrate layer; the light reflecting layer comprises a plurality of triangular-cone micro prisms.
Further, the substrate layer and the reflective layer are integrally formed. The base material layer and the reflecting layer are made of the same material.
The thickness of the reflecting unit layer is 50-300 mu m. Further, the thickness of the reflecting unit layer is 190 μm.
The triangular pyramid microprism comprises three side surfaces and a bottom surface, wherein the three side surfaces are triangular, the three side surfaces are intersected to form the vertex of the triangular pyramid (also called the top of the microprism), and the bottom surface is triangular. The bottom surface is arranged on the lower surface of the base material layer. Further, the bottom surface is an equilateral triangle.
Further, the tops of the triangular pyramid microprisms are bonded with the upper surface of the link transition layer.
Furthermore, the reflecting unit layer is used for reflecting most of the incident light, the structure of the general reflecting unit layer is a triangular-cone microprism array structure, and the independent repeating unit is a triangular-cone microprism.
Further, the material of the reflective unit layer is selected from one of Polycarbonate (PC), polymethyl methacrylate (PMMA), polyvinyl chloride (PVC), and polyethylene terephthalate (PET). The refractive index of the light reflecting unit layer is n 2.
Further, the ratio N2/N1 of the refractive index N2 of the light reflecting unit layer and the refractive index N1 of the linking transition layer is N. The ratio N is 0.5-2.5.
Further, the ratio N is 0.8-2.
Further, the ratio N is 1-1.5.
Furthermore, the weather-resistant mask layer is used for providing reliable protection for the microprism reflective product against outdoor environmental damage, and the weather resistance requirement of the road traffic microprism reflective film is generally 7-10 years.
Further, the material of the weather-resistant mask layer is selected from one of Polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), polyvinyl monofluoride (PVF), PMMA, Polyimide (PI), and acrylonitrile-butadiene-styrene terpolymer (ABS).
The thickness of the weather-resistant mask layer is 50-100 mu m. Further, the thickness of the weather-resistant mask layer is 75 μm.
The thickness of the focusing reflection layer is 5-125 μm, the side length of the regular hexagon of the concave focusing reflection lens is 2-50 μm, the distance (also called gap) between the sides of the adjacent concave focusing reflection lenses is 0.2-5 μm, and the depth of the concave cambered surface of the concave focusing reflection lens is 2-25 μm. The thickness of the link transition layer is 2-20 μm. The chain transition layer sequentially comprises an upper adhesive layer, a supporting layer and a lower adhesive layer from top to bottom, the upper adhesive layer and the lower adhesive layer are collectively called as adhesive layers, in the preparation process, raw materials of the adhesive layers are firstly prepared into glue, and the glue comprises 20-79% of acrylic ester, 20-79% of methacrylate and 0.1-1.5% of delayed cross-linking agent; the percentage is mass percentage. The delayed crosslinking agent comprises a photosensitive crosslinking agent and a thermosensitive crosslinking agent, and the mass ratio of the photosensitive crosslinking agent to the thermosensitive crosslinking agent is 0.1-1.5. The refractive index N2 of the light reflecting unit layer and the refractive index N1 of the link transition layer have a ratio N2/N1 equal to N, and the ratio N is 0.5-2.5. The foregoing technical solutions include examples 1 to 13.
Furthermore, the thickness of the focusing reflecting layer is 10-75 μm, the side length of the regular hexagon of the concave focusing reflecting lens is 6-35 μm, the gap between the sides of the adjacent concave focusing reflecting lenses is 0.5-3 μm, and the depth of the concave cambered surface of the concave focusing reflecting lens is 8-20 μm. The thickness of the link transition layer is 5-15 μm. In the preparation process, raw materials of the adhesive layer are firstly prepared into glue, and the glue comprises 35-64% of acrylic ester, 35-64% of methacrylate and 0.3-1.2% of delayed crosslinking agent; the percentage is mass percentage. The delayed crosslinking agent comprises a photosensitive crosslinking agent and a thermosensitive crosslinking agent, and the mass ratio of the photosensitive crosslinking agent to the thermosensitive crosslinking agent is 0.3-1. The refractive index N2 of the light reflecting unit layer and the refractive index N1 of the link transition layer have a ratio N2/N1 equal to N, and the ratio N is 0.8-2. The foregoing technical solutions include examples 5 to 13.
Furthermore, the thickness of the focusing reflecting layer is 25-50 μm, the side length of the regular hexagon of the concave focusing reflecting lens is 12-25 μm, the gap between the sides of the adjacent concave focusing reflecting lenses is 0.8-1.5 μm, and the depth of the concave arc surface of the concave focusing reflecting lens is 12-15 μm. The thickness of the link transition layer is 8-12 μm. In the preparation process, raw materials of the adhesive layer are firstly prepared into glue, and the glue comprises 39-55% of acrylic ester, 44.5-60% of methacrylate and 0.5-1% of delayed crosslinking agent; the percentage is mass percentage. The delayed crosslinking agent comprises a photosensitive crosslinking agent and a thermosensitive crosslinking agent, and the mass ratio of the photosensitive crosslinking agent to the thermosensitive crosslinking agent is 0.5-0.8. The refractive index N2 of the light reflecting unit layer and the refractive index N1 of the link transition layer have a ratio N2/N1 equal to N, and the ratio N is 1-1.5. The foregoing technical solutions include examples 9-13.
The invention provides a preparation method of a high retro-reflection microprism reflective film, which comprises the following steps:
(1) preparing a semi-finished product of the weather-resistant mask layer and the reflective unit layer composite film;
(2) preparing a link transition layer;
(3) preparing a focusing reflecting layer;
(4) and (3) bonding the focusing reflecting layer obtained in the step (3) with the weather-resistant surface film layer obtained in the step (1) and the semi-finished product of the reflecting unit layer composite film obtained in the step (2) through the link transition layer to prepare the high retro-reflecting micro-prism reflecting film.
Further, the step (1) comprises a hot-bonding and hot-pressing micro-molding process.
Further, the step (2) comprises a coating and UV curing process.
Further, the step (3) comprises coating, micro-replication, UV curing and vacuum aluminum plating processes.
Further, the step (4) includes a laminating and curing process.
Further, the preparation method of the high retro-reflective micro-prism reflective film comprises the following steps:
(1) firstly, unreeling a weather-resistant surface film layer and a reflecting unit layer substrate together, thermally laminating the lower surface of the weather-resistant surface film layer and the upper surface of the reflecting unit layer substrate together through a thermal lamination process, matching with a metal microprism mold, and preparing a triangular-cone microprism on the lower surface of the reflecting unit layer substrate through a hot-pressing micro-forming process, so as to obtain a semi-finished product of the weather-resistant surface film layer/reflecting unit layer composite film, wherein the semi-finished product of the step is marked as a semi-finished product 1.
(2) And then, precisely coating glue on the surface of the supporting layer, forming an adhesive layer through a UV curing process, and preparing a link transition layer (double-sided tape) for rolling and standby.
(3) The method comprises the steps of obtaining a concave focusing reflecting lens on a reflecting substrate by a precise coating process, a precise micro-replication process and a UV curing process in cooperation with a coating liquid formula for forming the concave focusing reflecting lens, and then obtaining an aluminum coating on the formed concave reflecting lens by a vacuum aluminum plating process, so as to obtain a focusing reflecting layer semi-finished product, wherein the semi-finished product in the step is marked as a semi-finished product 2.
(4) Finally, the semi-finished product of the weather-resistant surface film layer/reflecting unit layer composite film and the focusing reflecting layer are pasted together through a surface pasting process, namely the reflecting unit layer of the semi-finished product 1 and the concave focusing reflecting lens of the semi-finished product 2 are pasted together through a linking transition layer, and finally the finished product of the high retro-reflection microprism reflecting film provided by the invention is formed.
On one hand, the high retro-reflection microprism reflective film provided by the invention removes a heat seaming layer in the traditional microprism reflective film, and a link transition layer (namely transparent double-sided adhesive tape) is introduced, so that the number of effective retro-reflection units is greatly increased. Meanwhile, the bonding mode is changed from the traditional partial region bonding to the bonding of the upper surface of the link transition layer with the tops of all the light reflecting units (microprisms), so that the bonding force is improved, and the use is more durable.
Furthermore, the invention realizes the reutilization of partial stray transmission light, firstly, the matching (N value) of the refractive indexes of the connecting transition layer and the reflecting unit layer is limited, when the stray transmission light is emitted from the top of the microprism of the reflecting unit layer, because the refractive indexes of the connecting transition layer and the reflecting unit layer are similar, the light can easily pass through the connecting transition layer, when the stray transmission light is emitted from the non-vertex position of the microprism of the reflecting unit layer, the stray transmission light firstly contacts with the light sparse medium (a small amount of air layer between the connecting transition layer and the side surface of the microprism) and then reaches the light dense medium of the connecting transition layer, and the partial light passes through the light dense medium from the light sparse medium and can also easily pass through. When the stray light reaches the focusing reflection layer, firstly, the curved surface of the concave focusing lens is used for realizing that a part of light is reflected on the concave surface for multiple times, turns around and enters the link transition layer again, and then enters the light reflection unit layer, and finally, a small amount of light is reflected back near the direction area of the original incident light, so that the retro-reflection coefficient is improved; and the other part of light can be reflected, refracted and re-reflected for multiple times among the concave focusing lens (the surface of which is provided with the aluminum coating), the linking transition layer and the reflecting unit micro-prism, and finally, part of light can be reflected back from the vicinity of the original incident light, so that the improvement of the reflection coefficient (the improvement of the brightness) is realized.
The high retro-reflection microprism reflective film provided by the invention has the following beneficial effects:
the focusing reflecting layer provided by the invention is matched with the link transition layer to adhere the reflecting unit layer, so that the top of the micro prism on the reflecting unit layer is firmly bonded with the upper surface of the link transition layer, and meanwhile, the lower surface of the link transition layer is firmly bonded with the focusing concave reflecting lens to form a closed air layer, thereby providing higher reflecting cyclic utilization rate of stray transmission light. Firstly, in the process of bonding the micro prisms on the link transition layer and the reflection unit layer, the contact between the upper surface of the link transition layer and the top of the micro prisms is a point-to-surface bonding contact mode, so that the minimum filling damage to the micro prisms on the reflection unit layer is ensured, and the effective surface of the micro prisms on the reflection unit layer for completing retroreflection is completely reserved. Secondly, the upper surface of the link unit layer is contacted with a reflecting unit layer microprism array, and the side length is calculated to be 1cm according to the fact that the bottom surface of a common triangular pyramid microprism is an equilateral triangle and the side length is 120 mu m2The area of the light reflecting film is provided with a microprism array consisting of about 16000 single microprisms, so that the invention provides a bonding acting force mode that the upper surface of a link transition layer is contacted with the top of each microprism array on a reflecting unit layer, the bonding acting force cannot be reached by the stitching force locally generated by locally stitching the reflecting unit layer by the traditional stitching film, and the link transition layer provided by the invention adopts a delayed crosslinking mode and is used for carrying out a high-temperature high-humidity reliability testAnd then, the thermosensitive cross-linking agent in the link transition layer can further perform cross-linking reaction with acrylic acid, so that the viscosity of the link transition layer is further improved, the upper surface of the link transition layer is more firmly bonded with the reflecting unit layer, and the lower surface of the link transition layer is more firmly bonded with the focusing reflecting layer.
In the process of matching the link transition layer with the reflecting unit layer, the invention has a selection limit relation to the refractive indexes of the link transition layer and the reflecting unit layer according to the material selection condition of the reflecting unit layer, and the selection limit relation can ensure that stray transmission light which is not utilized in the micro prism of the reflecting unit layer smoothly passes through the link transition layer so as to reach the focusing reflecting layer adhered to the lower surface of the link transition layer, and after the lower surface of the link transition layer is adhered to the upper surface of the focusing reflecting layer, the link transition layer and the concave reflecting lens on the upper surface of the focusing reflecting layer form a new closed air layer. The transmitted stray transmission light reaches an aluminum coating (also called an aluminum-plated reflecting layer) on the concave focusing reflecting lens, and after the stray transmission light is in virtue of the radian of the concave focusing reflecting lens, the reflection path of the stray transmission light can be changed again at once, and the stray transmission light penetrates through the link transition layer and the reflecting unit layer to improve the reflecting brightness. And the other part of the stray transmission light can be reflected for multiple times by virtue of the radian of the concave focusing lens, transmitted for multiple times, reflected for multiple times, adjusted in light-emitting angle, finally passes through the link transition layer and the reflecting unit layer to form a part of available reflecting light source, so that the reflecting brightness of the whole reflecting film is improved.
The reflection brightness of the high-retroreflection microprism reflecting film provided by the invention is reduced by about 3% -12% before and after the bonding of the link transition layer, the reflecting unit layer and the focusing reflecting layer, and after high temperature and high humidity, the bonding strength of the link transition layer and the reflecting unit layer is about 5-9 times higher than that of the traditional sewing film and the reflecting unit layer.
The traditional retroreflective reflective film reduces the retroreflective refractive index (brightness) by 25-30% after being thermally sewn, reduces the retroreflective refractive index (brightness) by 3-12% after being pasted on the link transition layer, reduces little retroreflective refractive index (brightness), and equivalently improves the retroreflective refractive index (brightness) of a finished product, so the retroreflective microprism reflective film provided by the invention is called as a high retroreflective microprism reflective film.
According to the high retro-reflection microprism reflective film provided by the invention, after the reflective unit layer is attached to the link transition layer, the brightness is reduced little, namely, the brightness loss is low (the brightness loss rate is low), and after a high-temperature high-humidity test, the bonding strength of the reflective unit layer and the link transition layer is improved.
The high retro-reflection microprism reflective membrane can further improve the reflective brightness, and can provide higher weather resistance in the aspect of the cohesiveness of the reflective unit layer and the transition link layer.
Drawings
FIG. 1 is a schematic cross-sectional view of a highly retroreflective microprism reflective film according to the present invention;
FIG. 2 is a schematic cross-sectional view of a conventional microprism reflective film;
FIG. 3 is a top view of a conventional microprism reflective film;
FIG. 4 is a top view of a focusing reflector layer provided in accordance with the present invention;
fig. 5 is a bottom view of a retroreflective layer provided by the present invention.
Detailed Description
The present invention will be described in further detail with reference to specific examples, which should be noted that the present invention is only illustrative and should not be construed as limiting the scope of the present invention. Those skilled in the art may make insubstantial modifications and adaptations to the invention described above.
The retroreflection coefficient of the high retroreflection microprism reflecting film and the peeling force between the reflecting unit layer and the link transition layer are detected by adopting the following instruments and methods:
(1) the retro-reflection coefficient (brightness) of the reflective film is tested by adopting a Roadvista 932 device, the reflective film is a white reflective film, the brightness test has directionality, and the brightness change is tested in the transverse (90 degrees) direction and the vertical (0 degrees) direction respectively under the condition of the same observation angle and incidence angle. The brightness was tested against the surface of the weatherable topcoat layer.
(2) The stripping force of the reflective film after being subjected to high temperature and high humidity (85 ℃, 85% RH) for 200h is tested by adopting an INSTRON 3344 universal experimental tensile machine. The peel force is the peel force between the layer of reflective cells and the layer of link transitions.
Fig. 1 is a schematic view of a cross-sectional structure of a high retro-reflective micro-prism reflective film provided by the present invention, the retro-reflective micro-prism reflective film includes a weather-resistant surface film layer 1, a reflective unit layer 2, a triangular pyramid micro-prism array 3 made of the same material as the reflective unit layer by a hot-press micro-molding process, a link transition layer 4, an aluminum plating layer 5 formed on a concave focusing reflective lens by aluminum plating, a gap 6 between the top of the concave lens and a regular hexagon profile, a closed air layer 7 formed by the lower surface of the link transition layer being attached to the focusing reflective layer, a concave focusing reflective lens 8, a reflective layer substrate 9 constituting the focusing reflective layer, a bonding contact point 10 between the upper surface of the link transition layer and the top of the micro-prism array, and a focusing. The focusing reflective layer 11 of the present invention is composed of the above 5, 6, 8 and 9, and the reflective unit layer is composed of 2 and 3.
Fig. 2 is a schematic cross-sectional structure diagram of a conventional microprism reflective film, which includes an upper protective layer 12, a reflective layer 13, and a heat-sealing film 15, wherein the heat-sealing film 15 has a hot-melt adhesive thereon, and after ultrasonic welding or heat conduction, the hot-melt adhesive on the heat-sealing film 15 is melt-welded with a part of the microprism array in the reflective layer 13 to form a reflective ineffective area 14 and a partially sealed air layer 16.
Fig. 3 is a top view of a conventional microprism reflective film, which comprises a reflective effective region 17, a reflective ineffective region 14 formed by fusion welding a heat-sealing film with a part of a microprism array in a reflective layer after ultrasonic welding or heat conduction, generally, the outline side of a quadrilateral block 18 enclosed by the reflective ineffective region 14 shown in the schematic view of fig. 3 has a width of 500 μm and a length of 5000 μm, and for a quadrilateral block 18 enclosed by the reflective ineffective region 14, the part of the reflective ineffective region 14 (i.e. the outline side of the quadrilateral block 18, the area of 500 μm × 5000 μm × 4) caused by welding a hot melt adhesive on the sealing film with the microprism array comprises a reflective region composed of about 1600 microprism units.
Fig. 4 is a top view of the focusing reflective layer in the retroreflective microprismatic retroreflective sheeting of the present invention comprising the sides 19 of a regular hexagon and the gaps (i.e., edge-to-edge distances) 6 between the contours of the regular hexagons on the tops of adjacent concave lenses.
Example 1
As shown in fig. 1 and 4, the present invention provides a highly retroreflective microprism reflective film, which sequentially comprises, from bottom to top, a focusing reflective layer 11, a linking transition layer 4, a reflective unit layer 2, and a weather-resistant surface film layer 1.
The focusing reflection layer comprises a reflection substrate layer 9, the upper surface of the reflection substrate layer is provided with a focusing layer, and the focusing layer comprises a plurality of concave focusing reflection lenses 8. And a metal coating 5 is arranged on the focusing layer. The metal coating is an aluminum coating.
The material of the reflecting substrate layer is PET.
In the preparation process, raw materials of the focusing layer are firstly prepared into focusing coating liquid, and the focusing coating liquid comprises 40% of oxygen-containing functional group acrylic oligomer, 30% of nitrogen-containing functional group acrylic oligomer, 29.49% of active diluent, 0.5% of photoinitiator and 0.01% of flatting agent; the acrylic oligomer containing oxygen functional groups is selected from epoxy acrylate oligomer, the acrylic oligomer containing nitrogen functional groups is selected from aliphatic urethane (methyl) acrylate, the reactive diluent is pentaerythritol tetraacrylate, the photoinitiator is 2-hydroxy-2-methyl-1-phenyl-1-acetone (1173 for short) and the leveling agent is selected from polyether modified polydimethylsiloxane.
The outer contour of the concave focusing reflection lens is in a regular hexagon shape.
The thickness of the focusing reflection layer 11 (shown in fig. 1) is 5 μm, the side length of the regular hexagon of the concave focusing reflection lens is 2 μm, the gap 6 (shown in fig. 1) between the sides of the adjacent concave focusing reflection lenses is 0.2 μm, and the depth of the concave arc surface of the concave focusing reflection lens is 2 μm.
The chain transition layer sequentially comprises an upper adhesive layer, a supporting layer and a lower adhesive layer from top to bottom, and the upper adhesive layer and the lower adhesive layer are collectively called as adhesive layers.
The thickness of the link transition layer was 2 μm.
In the preparation process, raw materials of the adhesive layer are firstly prepared into glue, and the glue comprises 20% of acrylic ester, 79% of methacrylic ester and 1% of delayed crosslinking agent; the percentage is mass percentage.
The acrylate is isobutyl acrylate, and the methacrylate is n-butyl methacrylate.
The delayed crosslinking agent comprises a photosensitive crosslinking agent and a thermosensitive crosslinking agent. The photosensitive cross-linking agent is 1-hydroxy-cyclohexyl-phenyl ketone, and the thermosensitive cross-linking agent is selected from water-based isocyanate. The mass ratio of the photosensitive crosslinking agent to the thermosensitive crosslinking agent is 0.1:1 (may be abbreviated as "mass ratio of 0.1").
The reflecting unit layer 2 comprises a substrate layer and a reflecting layer, and the lower surface of the substrate layer is provided with the reflecting layer. The substrate layer and the reflecting layer are integrally formed. The base material layer and the reflecting layer are made of the same material.
The thickness of the light reflecting unit layer 2 is 190 μm.
The light-reflecting layer comprises a plurality of triangular pyramid microprisms 3 (shown in figure 1).
As shown in fig. 5, the triangular pyramid microprisms 30 comprise three side surfaces and a bottom surface, the three side surfaces intersecting to form the top 10 of the microprisms. The bottom surface is arranged on the lower surface of the base material layer of the reflecting unit layer 2.
Further, the top 10 of the triangular pyramid microprisms 30 are bonded to the upper surface of the link transition layer 4.
The material of the reflecting unit layer is selected from Polycarbonate (PC). The refractive index of the light reflecting unit layer is n 2.
The refractive index N2 of the light reflecting unit layer and the refractive index N1 of the link transition layer have a ratio N2/N1 equal to N, and the ratio N is 0.5.
The material of the weather-resistant mask layer is selected from Polytetrafluoroethylene (PTFE). The thickness of the weather-resistant mask layer is 75 micrometers.
Example 2-example 13
The technical parameters of the highly retroreflective microprismatic retroreflective sheeting provided in example 1 are shown in tables 1 and 2.
The results of testing the primary properties of the highly retroreflective microprismatic retroreflective sheeting provided in examples 1-13 are shown in table 3.
Comparative example 1
Traditional microprism reflective film 1: manufactured by 3M company, model: white 3930.
Comparative example 2
Traditional microprism reflective film 2: manufactured by seifei corporation, model number: white 5900.
The results of testing the main properties of the conventional microprismatic retroreflective sheeting provided in comparative examples 1-2 are shown in table 4.
Table 1 technical solutions of a reflecting unit layer, a weather-resistant surface film layer and a focusing reflective layer of a highly retroreflective microprism reflective film provided in embodiments 1 to 13 of the present invention
Table 2 technical solutions of the link transition layer of the highly retroreflective microprism reflective film provided in embodiments 1 to 13 of the present invention
Table 3 test results of the main properties of highly retroreflective microprismatic reflective films provided in examples 1-13
Table 4 test results of main properties of conventional microprismatic reflective films provided in comparative examples 1-2
As can be seen from the results shown in tables 3 and 4, the retroreflective microprism retroreflective sheeting of the present invention has low luminance loss after sewing, and has high bonding strength (high peel strength) between the link transition layer and the reflective unit layer after high temperature and high humidity. In particular, examples 9-13 provide highly retroreflective microprismatic retroreflective sheeting having a combination of improved performance properties.
The above description is only a preferred embodiment of the present invention, and is not intended to limit the scope of the present invention. All equivalent changes and modifications made according to the disclosure of the present invention are covered by the scope of the claims of the present invention.
Claims (10)
1. The utility model provides a high retro-reflective microprism reflective membrane which characterized in that, high retro-reflective microprism reflective membrane from the bottom up include focus reflecting layer, link transition layer, reflection of light unit layer and resistant time rete in proper order.
2. The retroreflective microprism sheeting of claim 1 wherein the focusing reflective layer comprises a reflective substrate layer, the upper surface of the reflective substrate layer is provided with a focusing layer, and the focusing layer is provided with a metal coating; the focusing layer comprises a plurality of concave focusing reflecting lenses.
3. The retroreflective microprism sheeting of claim 2 wherein the concave focusing reflective lens is formed from a focusing coating that is cured during the fabrication process; the focusing coating liquid comprises 40% of oxygen-containing functional group acrylic oligomer, 30% of nitrogen-containing functional group acrylic oligomer, 29.49% of reactive diluent, 0.5% of photoinitiator and 0.01% of flatting agent; the depth of the concave cambered surface of the concave focusing reflection lens is 2-25 mu m.
4. The retroreflective microprismatic retroreflective sheeting of claim 1 wherein the link transition layer comprises an upper adhesive layer, a support layer, and a lower adhesive layer in sequence from top to bottom, the upper adhesive layer and the lower adhesive layer being collectively referred to as an adhesive layer.
5. The retroreflective microprismatic retroreflective sheeting of claim 4 wherein the adhesive layer comprises a material selected from the group consisting of acrylates, methacrylates, and delayed crosslinkers; in the preparation process, the raw materials of the adhesive layer are firstly prepared into glue, and the glue comprises 20-79% of acrylic ester, 20-79% of methacrylate and 0.1-1.5% of delayed crosslinking agent; the percentage is mass percentage.
6. The retroreflective microprismatic retroreflective sheeting of claim 5 wherein the delayed crosslinking agent comprises a photosensitive crosslinking agent and a heat-sensitive crosslinking agent, wherein the photosensitive crosslinking agent and the heat-sensitive crosslinking agent are present in a ratio of about 0.1 to about 1.5:1 by mass.
7. The retroreflective microprism retroreflective sheeting of claim 1, wherein the reflective unit layer comprises a substrate layer and a reflective layer, and the reflective layer is disposed on the lower surface of the substrate layer; the light reflecting layer comprises a plurality of triangular-cone micro prisms.
8. The retroreflective microprismatic retroreflective sheeting of claim 1 wherein the refractive index of the reflective cell layer N2 and the refractive index of the linking transition layer N1 has a ratio N2/N1N, wherein N is from 0.5 to 2.5.
9. The retroreflective microprism retroreflective sheeting of claim 2 wherein the thickness of the focusing reflective layer is 5-125 μm, the side length of the regular hexagon of the concave focusing reflective lens is 2-50 μm, the distance between the sides of the adjacent concave focusing reflective lenses is 0.2-5 μm, the depth of the concave surface of the concave focusing reflective lens is 2-25 μm, and the thickness of the link transition layer is 2-20 μm; the chain transition layer sequentially comprises an upper adhesive layer, a supporting layer and a lower adhesive layer from top to bottom, the upper adhesive layer and the lower adhesive layer are collectively called as adhesive layers, in the preparation process, raw materials of the adhesive layers are firstly prepared into glue, and the glue comprises 20-79% of acrylic ester, 20-79% of methacrylate and 0.1-1.5% of delayed cross-linking agent; the percentage is mass percentage; the delayed crosslinking agent comprises a photosensitive crosslinking agent and a thermosensitive crosslinking agent, and the mass ratio of the photosensitive crosslinking agent to the thermosensitive crosslinking agent is 0.1-1.5; the refractive index N2 of the light reflecting unit layer and the refractive index N1 of the link transition layer have a ratio N2/N1 equal to N, and the ratio N is 0.5-2.5.
10. A method of making the highly retroreflective microprismatic retroreflective sheeting of any of claims 1-9 comprising the steps of:
(1) preparing a semi-finished product of the weather-resistant mask layer and the reflective unit layer composite film;
(2) preparing a link transition layer;
(3) preparing a focusing reflecting layer;
(4) and (3) bonding the focusing reflecting layer obtained in the step (3) with the weather-resistant surface film layer obtained in the step (1) and the semi-finished product of the reflecting unit layer composite film obtained in the step (2) through the link transition layer to prepare the high retro-reflecting micro-prism reflecting film.
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