MXPA99000236A - Anti-dew adhesive film - Google Patents

Abstract

An anti-dew article with an adhesive layer than results in improved durability to outdoor conditions is described. The anti-dew layer has a polymeric base layer and inorganic oxide particles surface layer. The adhesive that bonds the anti-dew film to a substrate is a cross-linked acrylate pressure sensitive adhesive with a low glass transition temperature and essentially no tackifiers. The adhesive is especially valuable for adhering an anti-dew film on a retroreflective traffic sign. The resulting sign exhibits excellent durability in a variety of weather conditions including cold weather.

Description

FILM RESISTANT TO HUMIDITY WITH DURABILITY ME JORADA Field of the invention This invention concerns articles that have an anti-humidity film bonded to a substrate using a layer of adhesive and methods for making these articles. Anti-humidity articles are particularly useful in retroreflective articles.

Introduction Retroreflective articles have the unique property that they are capable of returning a substantial part of the incident light to the light source over a wide range of incoming light angles. A main use of retroreflective articles is in traffic signals. At night, the light from the headlights of a motor vehicle turns on the traffic signal and is retroreflected back to the REF .: 29157 driver of the automotive vehicle. The bright image shown by the retroreflective signal makes the reading of the signal easier and gives the motorist more time to react.

The retroreflective signals commonly shown in the open air and therefore are frequently exposed to moisture droplets that form on its surface and weather conditions such as heat, cold, hail, etc. These environmental conditions can sometimes make it difficult for drivers of motor vehicles to read information about signals. Researchers in the retroreflective technique have recognized the existence of these problems for several years. For example, in 1946 Palmquist et al. in US Patent No. 2,407,680 showed the need for retroreflective signals to test for deterioration to the environment and retroreflective articles with water dispersing surfaces to minimize the effects of water droplets. Recently, traffic signs having an anti-humidity film (of the type described by Krautter et al., Comprised of inorganic oxides attached to a clean polymeric film by means of a layer holding the soluble functional organic) attached to the surface have been used. of a retroreflective traffic signal wherein the pressure sensitive adhesive (psa) is made of an acrylate / acrylic acid ester bonded with an adhesive tape. It has been found that in outdoor applications, the anti-humidity film is released from the signal, described above, but leaves the psa on the surface of the signal. This caused dirt buildup and reduced light transmission of the retro-reflective laminates. In addition, the psa turned yellow due to UV degradation, and blurred images appeared, with irregular shadows caused by the phase separation of the adhesive from the acrylic adhesive.

In this way, despite great and intense efforts in this area, there is a lag behind the need to make retroreflective articles with great durability in the open and an external antifog or anti-humidity surface.

Brief Description of the Invention The present invention provides an article with improved durability with an anti-humidity film on an outer surface. The inventive article comprises, at least, an anti-humidity film, and a layer of adhesive placed on the anti-humidity film. The adhesive comprises a pressure sensitive adhesive attached (psa). The psa is without an adhesive resin because it has been found that the presence of an adhesive in the adhesive layer causes undesirable properties. It is preferred that the adhesive layer have a glass transition temperature, Tg, less than about -15 ° C. The moisture film has an anisotropic structure with a polymeric base layer and a film with surface that disperses the water containing oxide particles. inorganic.

The inorganic particles in the layer that disperses the water have a lower coefficient of thermal expansion than the polymeric base layer; the anti-humidity film is anisotropic while the layer that disperses the water has a different coefficient of thermal expansion than the surface layer. As a result, changes in temperature cause the moisture film to coil. Thus, substrates such as retroreflective traffic signs tend to peel off in the anti-humidity film. The adhesive of the present invention has sufficient strength to counteract this tendency to wind, resulting in more durable moisture resistant articles.

The invention further provides a method for making an article with improved durability with an anti-humidity film in which an acrylate ester, a copolymerizable monoethylenic monomer and a binding agent combine to form a composition that is essentially free of adhesives, and the composition is cured to form a pressure sensitive adhesive. The pressure sensitive adhesive is placed between a substrate and an anti-moisture film, wherein the moisture film comprises a polymeric base layer and a surface layer where the inorganic oxide particles occupy at least a portion of the outer surface.

The present invention provides an excellent balance of properties and several advantages, even after exposure to the weather for several years, including: peel strength, cut resistance, clarity / no phase separation, yellowing, non-peeling, impact, economic and simplicity in the construction and preparation, durability to extremes of heat and cold, and resistance to enduring humidity.

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a sectional sectional view of a retroreflective signal according to a preferred embodiment of the invention.

Fig. 2 is a graph of data showing the increase in cut resistance with the increase in the concentration of the linking group.

DETAILED DESCRIPTION OF THE INVENTION The construction of a preferred embodiment of the invention is shown in the sectional sectional view in Fig. 1. The illustration in Fig. 1 shows the order of the layers in a preferred embodiment of the invention but they were not drawn to scale and they do not show exactly the relative thickness of each layer. In this embodiment, the retroreflective sheet 4 is mounted on a flat backing surface 2.

Typically the retroreflective sheet 4 is mounted on the flat back surface with a layer of pressure sensitive adhesive (not shown). The colored coating 6 with cut regions 7 is attached to a retroreflective layer by another pressure sensitive adhesive (not shown). The adhesive layer 8 bonds the moisture film 10 to the coating 6. In an alternative arrangement (not shown), where no coating is present, the adhesive layer 8 bonds the moisture film to the retroreflective layer. The surface of the moisture film 10 consists of the water dispersing layer 12 containing hydrophilic inorganic oxide particles 14.

In a preferred embodiment, the article of the present invention is a retroreflective traffic signal containing a layer of the retroreflective laminate. Examples of commercially available retroreflective laminates that can be used to make the graph include Scotchlite ™ High Grade Intensity Laminate Series 3870, Scotchlite1 Diamond Grade Refill Laminate Series 3990 Series, LDP Diamond Series 3970 Scotchlite ™ Reflector Laminate, available by 3M, St. Paul, Minnesota. The retroreflective laminate typically comprises a reflecting surface and optical elements. The reflecting surface serves to reflect the incident light towards the light source. The reflector material may comprise a metal reflector with mirror-like properties such as aluminum or silver (see, for example, US Patent No. ,283,101) or a diffuse reflector such as a pigment of a heavy metal or a polymeric material where the reflectance is caused by a difference in the refractive indexes in an interface (often a plastic-air interface). Optical elements typically come in one of two forms: composite lens elements and elements of cubic angles. Examples of retroreflective laminates employing elements of slow compounds have been described in U.S. Patent Nos. 2,407,680, 3,190,178, 4,025,159, 4,265,938, 4,664,966, 4,682,852, 4,767,659, 4,895, 428, 4,896,943, 4,897,136, 4,983,436, 5,064,272, and 5,066,099. Examples of retroreflective laminates employing cubic-corner elements have been disclosed in U.S. Patent Nos. 3,684,348, 4,618,518, 4,801,193, 4,895,428, 4,938,563, 5,264,063, and 5,272,562. The surface of the retroreflective laminate that coats the moisture film is a polymeric material, preferably an acrylate, more preferably polymethylmethacrylate. The surface may be impregnated with color pigments. A series of colored High Grade Intensity, VIP Diamond Grade, and LDP Scotchlite ™ Grade Diameters in colors such as yellow, orange, blue and green coffee are available from 3M, St. Paul, MN. The surface covering the opposite direction of the moisture film is typically covered with a layer of adhesive, preferably a pressure sensitive adhesive.

The flat back surface 2 is typically a metal, wood or polymeric material. Preferably, the flat back surface is a rigid material, with aluminum being the most common. The inventive article could also have a backing material of flexible polymeric material or a combination in which a flexible polymeric material is mounted on a rigid material such as aluminum or plywood. The flat back surface is preferred to be preferably opaque. Typical examples of commercially available flat backing plates include: an aluminum panel etched with "an acid and degreasing with a thickness of 2 mm (millimeters), a high density plywood with a thickness of 2 cm (centimeters), or a panel of glass fiber reinforced plastic with a thickness of 4 mm, all these flat backing surfaces are commonly used in traffic signal industries and are available from the Lyte Sign Company, Eden Prairie, MN.

The colored coating 6 is preferably a plastic sheet of about 25 μm to 125 μm, more preferably about 75 μm in thickness. The cuts are made in the coating layer. Typically the cuts are in the form of letters, numbers or other graphic information. The colored coating blocks the light of the selected wavelengths while the cuts do not allow the transmission of light impulse and from the retroreflective sheet. The uncolored regions can be replaced by cuts in the colored coating. The coating is usually adhered to the retroreflective sheet by an adhesive, preferably a pressure sensitive adhesive.

The adhesive used to bond the retroreflective sheet to the substrate or bond the colored coating to the retroreflective laminate may include the adhesives described herein or those otherwise known in the art. Colored coatings, written with adhesives of the type described herein with protective surfaces, are commercially available for application to retroreflective sheets on traffic signals. The adhesive layer placed between the retroreflective sheet and the colored coating is preferred to exhibit high clarity and at least moderately good adhesion and cut resistance.

The types of acrylate ester used to make the adhesive layer 8 include the C4-C10 alkyl acrylic and methyl acid esters. The acrylate ester preferably comprises acrylate or methacrylate ester monomers including ethyl acrylate, n-butylacrylate (BA), isobutyl acrylate, 2-methylbutylacrylate, 2-ethylhexyl acrylate, 2-ethylhexyl methacrylate, n-octyl acrylate, n-octyl methacrylate, isooctyl acrylate (IOA), isodecyl acrylate (IDA), isooctyl methacrylate, isononyl acrylate, isodecyl methacrylate, and mixtures thereof. The acrylate ester may also include hydroxyethyl methacrylate, hexylacrylate, hexylmethacrylate and may also include vinyl acetate and combinations of these with acrylates. The acrylate ester is more preferably isoocty lacrylate.

Preferably from about 85 to about 99, more preferably about 87 to about 98, and more preferably about 90 to about 97 weight percent of acrylate ester, based on the total weight of the resin precursors (e.g. initial materials do not include solvents) were used to form the adhesive layer.

Preferred copolymerizable monoethylene monomers include acrylic acid (AA), methacrylic acid, itaconic acid, ccrotonic acid, acrylamide, acrylonitrile, methacrylonitrile, maleic anhydride, fumaric acid and the like. The copolymerizable monoethylene monomers include N, N-dimethylacrylamide, N, N-dimethylmethacrylamide, N, N-diethylacrylamide, N, N-diethylmethacrylamide, N-vinylcaprolactam, and the like. The most preferred monoethylenically monomers are acrylic acid and methacrylic acid. Preferably from about 1 to about 15, more preferably from about 2 to about 12, and more preferably from about 3 to about 10 weight percent of copolymerizable monoethylene monomers based on the total weight of the resin precursors are used in the formation of the adhesive layer.

Examples of binding agents that may be used in the present invention include those described in U.S. Patent Nos. 3,440,242, 4,418,120 and 3,301,835. Preferred binding agents are di and tri functional aziridines such as trimethylolpropanetris- (B-N-aziridinyl) propionate. Most preferred are bis amides such as N, N-bis-propylenisophthalimide. As shown in Fig. 2, too small bonding agents result in an unacceptably low cutting resistance; On the other hand, too much binding agent causes a loss of adhesion due to interfacial failure.

Preferably the binding agent or agent is used at about 0.01 to about 0.1, more preferably about 0.02 to 0.08, and more preferably 0.03 to 0.06 percent solids.

The pressure sensitive adhesive bonded with acrylic can be formulated to bond with UV or electron beam radiation. Typically Psa joined by filiation are described by Martens in U.S. Patent No. 4,181,752.

Small amounts of UV light absorbers and light stabilizers of blocking amines can be incorporated into the pressure sensitive adhesive to prevent degradation in outdoor locations. Suitable UV light absorbers are benzotriazole compounds including Tinuvin ™ -328, Tinuvin ™ -P, and blocking amines include Tinuvin ™ -292, Tinuvin ™ -144, and Tinuvin ™ -622LD, available from Ciba-Geigy Co. Hawthorne NY. Other suitable UV light absorbers include benzophenone compounds such as Uvinul ™ -400, Uvinul ™ -490 and Uvinul ™ -N539, available from BASF Co. , Clifton NJ. Preferably, less than two weight percent of each UV light absorber and light stabilizers with blocking amines are incorporated into the pressure sensitive adhesive.

Kealy and Zen in U.S. Patent No. 4,418,120 show that the psa IOA / AA bound must contain an addition of rosin ester adhesion to achieve an excellent adhesion balance, adhesion detachment and cutting properties in an adhering psa. good to low energy surfaces. Surprisingly, and contrary to that shown by Kealy and Zenk, it is a discovery of the present invention that the presence of glues in the adhesive layer that binds the anti-humidity layer results in undesirable properties such as yellowing, peeling, phase separation between the adhesive and the glue, loss of transparency (e.g., hazy) with aging, and generally poor durability of the moisture-resistant retrsrreflector article. The failure of the bonded adhesive layer has been found to be more severe in regions where changes in seasonal temperature vary over a wide range such as from -40 ° C to 35 ° C. This may be due to the fact that the psa changes from an elastic phase to a vitreous phase at low temperatures, causing a reduction in the adhesion strength. Thus, the adhesive layer must be substantially free of glues; that is, the glue must not be present in sufficient quantities for the lowest durability of the moisture resistant article. Preferably, the glue should not be present in amounts sufficient to increase the Tg of the psa above about -15 ° C. The adhesive layer preferably has less than 5% by weight of glues. More preferably, the adhesive layer does not contain glues. The glues are typically naturally occurring materials, which are typically complex mixtures of high molecular weight organic acids and related neutral materials. The glues include wood resins, or modified forms of such resins that are found naturally, for example, hydrogenated or esterified resins, terpene polymers, pinene, etc. The glues include dark amber natural rubber resin (Nelio N available from Union Camp), pale thermoplastic resin derived from the polymerization of mixed olefins (Super Sta-Tac 80 available from Reichhold Chemicals, Inc.), synthetic polyterpene (Wingtack Plus available from Goodyear), medium soft R17 thermoplastic coumaron-indene resin supplied by Neville), terpen urethane resin (Iso-Terp, 95 available from Schenectady Chemicals Inc.), and pentaerythritol ester rosin (Foral 85 available from Hercules).

The moisture barrier layer comprises an organic polymeric base layer and a surface layer containing inorganic oxide particles. The inorganic oxide particles are hydrophilic and at least a part of these particles are exposed to the atmosphere. The base layer may contain some inorganic oxide particles but this has a lower low concentration than the surface layer. In a preferred embodiment, the base layer is a polymer, preferably a non-biaxially oriented flexible acrylate, this is essentially free of inorganic oxide particles, and the surface layer contains greater than 90% oxide particles, more preferably greater than 98% of oxide particles. The inorganic oxide particles are preferably silica, alumina, silicoaluminate or mixtures thereof. Examples of anti-humidity layers usable in the present invention include those described in U.S. Patent Nos. 4,755,425, 4,844,976, 5,073,404, 4,478,909 and 5,134,021; the water dispersing layers described in these patents could require a surface treatment to increase the concentration of the oxide particles on the surface. U.S. Patent No. 4,576,864 by Krautter et al discloses a particularly preferred anti-humidity layer. In a preferred embodiment, the silica particles in the surface layer are treated with an aluminate solution to improve the durability.

The retroreflective articles are made using assembly techniques known in the art. Typically, the retroreflective laminate with pressure sensitive adhesive and the protective layer are laminated on a flat backing surface by removing the protective layer and passing the laminate through a compression roller. A colored coating having cut regions is then applied on a retroreflective laminate. Typically, the colored coating has a layer of adhesive and a protective layer on the adhesive layer. The colored coating was cut smoothly using electronic cutters and the undesirable areas are removed. A removable pre-opaque adhesive tape is often applied to the removed colored coating to facilitate transfer to the signal surface. The protective layer is clamped and the coating is pressed onto the retroreflective laminate.

After lamination, the pre-plate tape (if present) is removed from the surface of the signal. The retroreflective signal at this stage is easy to apply the moisture resistant film with the pressure sensitive adhesive.

The adhesive used to apply the moisture film can be prepared by mixing the appropriate amounts of an acrylate ester (s) and polymerizable ethylenic monomer (s) in an organic solvent or mixtures of organic solvents. A linking group is added to the mixture. The resulting solution is then covered, preferably by roll coating in a paper-covered silicone protection layer. The solvent is removed by evaporation and the adhesive is cured. In a preferred embodiment, an IOA / AA adhesive with a bis amide bonding group is cured by heating at about 150 ° C for about 10 min. An anti-humidity layer is applied on the adhesive layer, for example when passing through a compression roller.

The anti-humidity film thus produced with adhesive and the removable protective layer can be stored for future use. The removable protective layer can be detached and the exposed adhesive pressed into the traffic signal.

The psa for the anti-humidity film preferably has strong adhesion over the temperature range from -40 ° C to 35 ° C. The retroreflective signal preferably does not exhibit visual yellowing after 10 years of exposure to the weather. the adhesive must retain good clarity. The acrylic copolymer in the psa is bonded to provide good peel strength and cut resistance over service temperatures of -40: C to 35 'C. The psa must have great transparency, preferably the psa layer is greater than 85% transparently, more preferably greater than 90% transparent to visible light. The psa preferably have a Tg, as measured by differential scanning calorimetry- ASTM E1356, of less than -15 DC, more preferably less than -20 ° C. Preferably, the psa has a peel strength such that an article with an adhesive layer with a thickness of 3 mil. it has a peel strength of 90 greater than 3, and more preferably greater than 4 lbs / inch at 0 ° C. Preferably the retroreflective signals resistant to moisture have an impact resistance such that 1.39 kg. Impact on the backing of the signal at -10 ° C does not cause delamination of the film resistant to moisture, more preferably 1.39 kg.m impact the signal backing at -22 ° C does not cause delamination of the moisture resistant film . Preferably the retroreflective signals have good adaptation to the environment such that the signal retains more than 90% retroreflectivity and has a yellowness index of less than 5 after exposure to 3000 hours of repeated cycles of 4 hours of UV light at 60 ° C and 4 hours of moisture condensation at 50 ° C according to ASTM G53.

EXAMPLES A rolling test of the film was conducted to determine the tendency to wind the moisture film caused by variations in temperature. An anti-humidity film (Folie farblos 99840, by Rhom Gmbh, Chemische Fabrik, Germany - the film is an approximately 50 μm thick acrylic film) was cut into circles with a diameter of 7.62 cm and placed on a flat plastic surface and held at a specified temperature for 30 minutes. As a result of the heat treatment, the sample wound with the surface of inorganic oxide in the internal diameter, and the rope or, if it was wound in a tube, the diameter of the sample was measured. Surprisingly, the thermally aged specimens remained coiled after returning to room temperature. The results are shown in Table 1. In comparison, the acrylic-based non-silica-coated film (Rhom No. 99845) remained flat at all temperatures. The colored coating film without PSA (Scotch ™ Series 1170 Electronically Screeable Coating film, available from 3M, St. Paul MN) also remained flat at all temperatures.

The winding character shown in Table 1 is caused by the difference in the * thermal expansion between the acrylic base layer and the surface layer with silica, and the internal stress created during the drying of the silica coating. The degree of winding can be used to calculate the winding force; see S. Wu, Polymer Interface and Adhesion, Marcel Dekker, Inc., NY, pp. 465-473 (1982). While the coating shrinks, the substrate is bent with the coating on the concave side. In preferred embodiments, the adhesive was designed with sufficient strength to counteract the winding force that can be caused by heating and cooling the retroreflective article.

To prepare a bonded pressure sensitive adhesive, a mixture containing 384.6 parts of the adhesive solution (93: 7 IOA / AA copolymer, 26% solids in a solvent mixture of about 46% ethyl acetate, 26% heptane and 2% cyclohexane) and 0.043 parts of N, N-bispropylene-phosphthalimide was coated with a knife on a protective layer of paper coated with silicone and heated in a forced oven with air at 170 ° F for 1.7 min., 270 ° F for 1.7 min., And 350 ° F for 1.7 min., To remove the solvents and produce a thickness of 2 mil (0.5 mm), dried, bonded the adhesive layer.

The anti-humidity film (Rohm GmbH No. 99841) was then laminated to the outer side coated with the bonded adhesive using a compression pressure of 60-70 psig using a group of compression rollers 36"wide with soft rubber coating. This produced a clean pressure sensitive coating film with moisture resistant coating on the exposed outer surface Samples prepared according to this procedure refer to example 1.

A comparative example was prepared using the psa shown by Kealy et al. Of U.S. Patent No. 4,418,120. For a solution of 100 parts by weight of I0A: AA (94: 6), 30 parts of rosin ester glue resin (Foral 85- a glycerol ester of stabilized rosin having a softening point of 82 ° C) were added. , available from Hercules, Inc.) to form approximately a 45% solids mixture in a mixture of acetone, toluene, and heptane. Prior to the coating, a binding group of 0.075 parts of N, N-bispropylenisophthalimide per 100 parts dry weight of the adhesive was added to the mixture and mixed well for 15-30 min. with a mixer with propellers. The resulting mixture was coated on the release liner and dried and cured as in Example 1.

Coated acrylic pressure sensitive adhesives containing various levels of bisamide bonding group from 0.025 to 0.060 parts per hundred parts of acrylic polymer were tested for adhesion cut (pull energy) by the following modified version of PSTC-7 Test of Cutting (Agreed Method for the Pressure Sensitive Tape): The adhesive was laminated to an acrylic coating film to make an adhesive tape. The tape was cut into 1.27-cm wide x 8 cm long strips and applied to the Scotchlite ™ (Diamond Grade ™ VIP 3990) Retrorreflector laminate which was mounted on a 70 mm x 70 mm x 1.0 mm aluminum panel thick. The length of the adhesive superimposed on the reflector laminate was 2.54 cm giving a superimposed area of 3.22 square cm. The final part of the tape without application was reinforced with Scotch ™ filament tape to prevent tearing under load. After conditioning the samples for 24 hr. of residence time at constant temperature and humidity, a load of 1 kg. it was suspended from the free end of the tape, with the test panel in vertical orientation. The time for the weight to fall (due to the sliding of the adhesive at room temperature) was recorded as the cut-off time to failure.

As Figure 2 indicates, the cut-off time to failure while increasing the load of the joint. Cutting rates (at room temperature) of approximately 5,000-15,000 min. were desired for good sliding and shrinkage resistance of the pressure sensitive coating film. This range of adhesion cut was obtained with preferred binding group levels from about 0.03 to 0.06 parts of bisamide per 100 parts of acrylic polymer.

Test specimens for measuring reverse impact at low temperature were prepared by laminating a psa moisture film on a VIP retro-reflective laminate (3990) (available from 3M, St. Paul, MN) on a 6-inch aluminum panel. 6 inches (15 cm x 15 cm), which has a thickness of 0.080 inches (0.023 cm). All specimens were conditioned at room temperature for at least 24 hours to allow adhesion for total development. Afterwards, the specimens were cooled in a cooler at -8 ° F (-22 ° C), 20 ° F (-7 ° C) and 40 ° F (4 ° C) for the entire night before the test. In the test, the specimens were placed on a steel metal ring that has a diameter of 3"with the anti-humidity film and the lower surface of the retroreflective laminate.A surrounding steel bar that weighed 1.98 kilograms was raised to 46.5 or 70 cm and it was dropped freely to hit the specimen backing surface to create an impact force of 0.92 or 1.39 kilogram-meters, respectively The results are shown in Table 3. This test method is similar to ASTM 0-2794 with only a slight modification of the serrated diameter.

The inventive films were subjected to a 90 ° peel test. In this test, the samples were prepared according to Example 1 but varying the thickness of the film. The anti-humidity films, 2.54 cm wide by 20 cm long, were laminated to the HIS 3870 laminate (available from 3M Corp., St Paul MN) by passing through a compression roller afterwards, the HIS 3870 laminate was laminated to a defatted aluminum plate. To ensure that the psa fault occurred instead of the anti-humidity film, the moisture film was reinforced with Scotch ™ filament packing tape before the test. The prepared specimens were allowed to sit for at least one day, then cooled to the test temperature for at least two hours before the test. The 90 ° peel strength was measured according to ASTM D3330-78. The cooling chamber was fixed to an Instron test apparatus and the Instron cross-pressure rate was monitored at 10 cm / min. Results are shown in table 2.

The weather resistance and clarity of the pressure sensitive adhesive were measured from the coefficient of retroreflection and the yellowness index before and after an exposure test of accelerated UV light in a meter of exposure to the environment. Scotchlite ™ Grade No. 3870 High Intensity retroreflective laminate was laminated on an aluminum test panel, 7 cm wide, 28 cm long and 1 mm thick. The coefficient of retroreflection of the laminate is 336 cdl / lux / mX measured at an angle of light input of 4 ° and an observation angle of 0.2 °, in accordance with ASTM E810. The acrylic film without the inorganic oxide layer (Rohm No. 99845) was laminated with the psa bond described above at a compression pressure of 60 psi. The yellowness index on the retroreflective panel was measured with a Hunter LabScan Spectrocolorimeter available from Hunterlab, Inc., Reston VA, in accordance with ASTM D1925. The environmental durability of the specimens was tested on an environmental exposure meter in accordance with ASTM G53. The light source in the environmental exposure meter was a UV light lamp with a maximum intensity at 313 cm-1. The test specimens were again measured after 3000 hours of repeated cycles of 4 hours of UV light at 60 ° C and 4 hours condensing the moisture at 50 ° C. The results are shown in Table 4.

Specimens from the film using the psa .inventivo (Exp. 1) and the comparative psa both retained more than 90% retroreflectivity. The retroreflective laminate without a coated psa or film exhibits an increase in the yellowness index of 4.9 units, the laminate with the psa of Exp. 1 was increased by approximately 10 units. Visually, the specimen with the comparative psa showed yellowing while the specimens with the inventive psa shown did not show yellowing. Thus the yellowing of the comparative example is mainly caused by the degradation of the UV light of the glue resin.

All patents mentioned herein are incorporated by reference as long as they are reproduced fully as before. While this invention has been described in connection with the specified embodiments, they are not limited to the specific embodiments and include equivalents to those described herein.

Table 1 PROOF OF ROLLING THE FILM Table 2 90 TEST DETACHMENT TEST 3 LOW TEMPERATURE IMPACT TEST TABLE 4 EXPOSURE TO THE ACCELERATED ENVIRONMENT It is noted that in relation to this date, the best method known to the applicant to carry out the aforementioned invention, is that which is clear from the present description of the invention.

Having described the invention as above, the content of the following is claimed as property.

Claims (5)

1. CLAIMS 1. An article with improved durability with anti-humidity film on an exterior surface, characterized in that it comprises: an anisotropic anti-humidity film comprising a polymeric base layer and a surface layer where the inorganic oxide particles occupy at least a portion of the outer surface; Y an adhesive layer placed on the surface of the polymeric base layer opposite the outer surface containing inorganic oxide particles; wherein the adhesive layer comprises an acrylate pressure sensitive adhesive for bonding, and wherein the adhesive layer is essentially without an adhesive.
2. 2. The article of claim 1, characterized in that the adhesive layer has a Tg between about -15 X and -50"C were measured by differential scanning calorimetry according to ASTM E1356.
3. 3. The article of claim 1-2, characterized in that the anti-humidity film comprises a non-bioaxial oriented acrylic film and a layer of inorganic oxide particles placed on a surface of the film.
4. 4. The article of claim 1-3, characterized in that the article is a retroreflective signal including a flat backing surface, the retroreflective laminate and a colored coating.
5. 5. The article of claims 1-5, characterized in that the anti-humidity film, before being bonded with an adhesive layer, has a tendency to latent coiling such that the film will exhibit a degree of curvature of at least 0.5 after heating at about 54; for an hour. 7. The article of claims 1-6, characterized in that the reactive materials used to make the adhesive layer consist essentially of about 90 to about 98 percent isooctyl acrylate, about 2 to about 10 weight percent acrylic acid and about 0.01 to about 0.05 weight percent of a bis-amide linking group. 8. The article of claims 1-7, characterized in that the surface layer of the moisture barrier layer is more than 90 weight percent oxide particles, and where in the base layer it is essentially free of oxide particles. 9. The article of claims 1-8, characterized in that it has a peel strength of at least 4 psi at 0 ° C and at least 2 psi at -10 ° C and that it has a cut resistance of at least 5000. minutes as measured by the modified version of the PSTC-7 cut test described here. 10. The article of claims 1-9, characterized in that it has a yellowness index of less than 5 after exposure to 3000 hours of repeated cycles of 4 hours of UV light at 60 ° C and 4 hours condensing moisture at 50 ° C. according to ASTM G53 and having reverse impact resistance such that the anti-humidity films do not exhibit delamination after an impact force of 1.3 (kg) (m) at -8 ° F. 11. A method for making an article resistant to moisture, characterized in that it comprises the steps of: combining an acrylate ester, a copolymerizable monoethylene monomer and a binding agent to form a composition; and where the composition is essentially without glues; rolling the composition to form a pressure sensitive adhesive; placing the pressure-sensitive adhesive on an anti-humidity film, wherein the moisture-proof film comprises a polymer-based layer and a surface layer wherein the inorganic oxide particles occupy at least a portion of the outer surface. 12. The method of claim 11, characterized in that the combining step consists essentially of combining 92 to 98 weight percent of isooctilacrylate, 2 to 8 weight percent of acrylic or methacrylic acid and a linking group selected from the group consisting of of bis amides and aziridines. 13. The method of claims 11-12, characterized in that the anti-humidity film is subsequently applied on a retroreflective traffic signal to form a moisture resistant traffic signal.