Low-flammability adhesive composition having a layered structure

Abstract

The present disclosure relates to a low-flammability film structure. The film structure includes a film layer, a first adhesive layer having at least 41% by weight of a flame-retardant additive, and a second adhesive layer. The total thickness of the adhesive layers ranges from 18.5 to 44.5 microns. The total thickness of the flame-retardant adhesive layers is 32% to 85% of the total adhesive thickness.

Description

[Technical Field]

[0001] The present disclosure relates to film articles having layered adhesive structures, where at least one adhesive layer includes a flame retardant additive. [Background technology]

[0002] Many countries have low flammability or low ignition requirements for film products applied to surfaces such as the interior or exterior of buildings such as hotels, schools, hospitals, or restaurants, or to vehicles such as trains, tractor-trailers, or personal vehicles or aircraft. Such requirements can help increase safety for individuals within the area by reducing the likelihood of explosion or fire spread in the event of a spark or ignition.

[0003] At the same time, many customers also have adhesive tack and release requirements when purchasing a film to ensure that the film will hold up well, remain adhered to the desired surface for the desired period of time, and can be removed when desired.

[0004] It can be difficult to create a product that simultaneously meets both low flammability and low flammability requirements and adhesive requirements. Summary of the Invention

[0005] The present invention provides a method for reducing the flammability or ignition potential of film structures while maintaining good adhesive tack and release. The present disclosure provides a solution for constructing films thin enough to meet Fire Growth Rate (FIGRA) and Total Heat Release (THR) requirements established by various jurisdictions or customers. In some jurisdictions, meeting FIGRA and THR while maintaining acceptable adhesive properties can be very challenging. Even if the film is thin, the layered adhesive structure of the present disclosure allows the film to also meet the adhesive requirements.

[0006] In one example, the present disclosure includes a low-flammability film structure. The film structure includes a film layer, a first adhesive layer having at least 41% by weight of a flame-retardant additive, and a second adhesive layer. The total thickness of the adhesive layers is in the range of 18.5 to 44.5 microns, and the total thickness of the flame-retardant adhesive layers is 32% to 85% of the total adhesive thickness.

[0007] In another example, the present disclosure includes a low-flammability film structure. The film structure includes a film layer, a first adhesive layer having at least 41% by weight of a flame-retardant additive, and a second adhesive layer. The total thickness of the flame-retardant adhesive layers is 32% to 85% of the total adhesive thickness, and the film has a peel adhesion strength of 20 N or greater under a 180° peel adhesion test.

[0008] In another example, the present disclosure includes a low-flammability film structure. The film structure includes a film layer, a first adhesive layer having at least 41% by weight of a flame retardant additive, and a second adhesive layer. The total thickness of the adhesive layers is in the range of 18.5 to 44.5 microns, and the film has a flame retardancy of 8 MJ / m under a flammability test. 2 The film structure has a total heat dissipation of 8KW / (m 2* s) or less fire growth rate (FIGRA).

[0009] In some examples, the film layer comprises at least one of polyvinyl chloride (PVC), polyester, polyethylene terephthalate, low density polyethylene, ethylene methacrylate copolymer, polypropylene, polyimide, polyurethane, polyvinylidene fluoride, polymethyl methacrylate, acrylic, silicone, and polyolefin films.

[0010] In some instances, the film is a graphic film and the ink layer is deposited on the film layer.

[0011] In some cases, the film layer has a thickness of 200 microns or less.

[0012] In some cases, the film layer has a thickness in the range of 125 to 145 microns.

[0013] In some cases, the first adhesive layer is adjacent to the film layer.

[0014] In some examples, the film structure further includes a third adhesive layer, the third adhesive layer having no flame retardant additive, the third adhesive layer being disposed between the film layer and the first adhesive layer.

[0015] In some examples, the first adhesive layer includes at least one of an acrylic adhesive, natural rubber, synthetic rubber, silicone, polyester, polyolefin, rosin, and epoxy adhesive resin, but is not limited to these common pressure-sensitive adhesive resins.

[0016] In some examples, the second adhesive layer comprises an acrylic adhesive.

[0017] In some examples, the film construction has a peel adhesion of 20 N or greater under a 180 peel adhesion test.

[0018] In some cases, the film structure has a flame resistance of 8MJ / m under flammability testing. 2 The total heat dissipation is as follows:

[0019] In some examples, the film structure has a power rating of 8KW / (m 2* s) or less fire growth rate (FIGRA).

[0020] In some examples, the flame retardant additive includes at least one of tris(tribromoneopentyl)phosphate (TTBP), antimony trioxide (ATO) flame retardant, ammonium polyphosphate (APP) flame retardant, alumina trihydrate (ATH) flame retardant, and antimony trioxide (SbO2) flame retardant.

[0021] In some examples, the film structure further includes a third adhesive layer, the third adhesive layer having no flame retardant additive, the third adhesive layer being disposed between the film layer and the first adhesive layer.

[0022] In some examples, the first adhesive layer includes at least one of an acrylic adhesive, natural rubber, synthetic rubber, silicone, polyester, polyolefin, rosin, and epoxy adhesive resin, but is not limited to these common pressure-sensitive adhesive resins.

[0023] In some examples, the flame retardant additive includes at least one of tris(tribromoneopentyl)phosphate (TTBP), antimony trioxide (ATO) flame retardant, ammonium polyphosphate (APP) flame retardant, alumina trihydrate (ATH) flame retardant, and antimony trioxide (SbO2) flame retardant. [Brief explanation of the drawings]

[0024] The present invention can be more fully understood from the following detailed description considered in conjunction with the accompanying drawings. [Figure 1] FIG. 1 shows a film structure having two adhesive layers. [Figure 2] FIG. 1 shows a film structure having three adhesive layers. [Figure 3] FIG. 1 shows a film structure with a liner.

[0025] Structural changes may be made and utilized in the embodiments shown and described herein without departing from the scope of the present invention. The figures are not necessarily to scale. Like numbers used in the figures refer to like components. However, the use of a number to refer to a component in a given figure is not intended to limit the component in another figure bearing the same number. DETAILED DESCRIPTION OF THE INVENTION

[0026] FIG. 1 shows a film structure 100 having two adhesive layers 104, 106 applied to a substrate 108. The film 102 may be any suitable film, such as a film comprising polyvinyl chloride (PVC), polyester, polyethylene terephthalate, low-density polyethylene, ethylene methacrylate copolymer, polypropylene, polyimide, polyurethane, polyvinylidene fluoride, polymethyl methacrylate, acrylic, silicone, and polyolefin films, or any combination thereof. The film 102 may be calendered or cased and may be made of any of the materials discussed herein (including the Examples). The thickness of the film 102 may vary. For example, it may range from about 20 μm to 300 μm. The thickness of the film 102 may be approximately 20 μm, 30 μm, 40 μm, 50 μm, 60 μm, 70 μm, 80 μm, 90 μm, 100 μm, 125 μm, 150 μm, 175 μm, 200 μm, 225 μm, 250 μm, 275 μm, and 300 μm, or any range between any of the foregoing values. The maximum thickness of a particular film will depend on various factors, including the relative flammability of the polymers in the film.

[0027] The film 102 may be a graphic film. It may have colors, patterns, textures, or images printed with various inks and methods. In some examples, the film 102 may be transparent or translucent. The film 102 may have various opacities and a wide variety of colors. In some examples, the film 102 may be a functional film that provides functions including abrasion resistance, easy cleaning, or surface protection from damage.

[0028] The adhesive layer 104 is disposed between the film layer 102 and the adhesive layer 106 and is adjacent to each of the film layer 102 and the adhesive layer 106. In some cases, a primer may be added between the film layer 102 and the adhesive layer 104 to increase adhesion between the two layers. If a primer layer is used to bond the film layer 102 and the adhesive layer 104, the film layer 102 and the adhesive layer 104 are considered adjacent. The adhesive layer 104 includes an adhesive and a flame retardant additive 105. Some examples of adhesives that may be used in the adhesive layer include acrylic adhesives, natural rubber, synthetic rubber, silicone, polyester, polyolefin, rosin, and epoxy adhesive resins (not limited to these common pressure-sensitive adhesive resins), as well as combinations thereof. The adhesive layer 104 may be the same adhesive as the adhesive layer 102 or a different adhesive. Factors contributing to the selection of the type of adhesive include the desire for the adhesive to adhere well to the film layer or for the adhesive layers to adhere well to each other. Some examples of suitable flame retardants include tris(tribromoneopentyl)phosphate (TTBP), antimony trioxide (ATO) flame retardant, ammonium polyphosphate (APP) flame retardant, alumina trihydrate (ATH) flame retardant, and antimony trioxide (SbO2) flame retardant. The flame retardant additive 105 may be added in an amount of, for example, 30 wt%, 35 wt%, 40 wt%, 45 wt%, 50 wt%, 55 wt%, 60 wt%, 65 wt%, 70 wt%, 75 wt%, or 80 wt%. The total thickness of adhesive layer 104 may be about 8 μm, 10 μm, 12 μm, 15 μm, 20 μm, 25 μm, 30 μm, 35 μm, 40 μm, 45 μm, 50 μm, 55 μm, 60 μm, 65 μm, 70 μm, 75 μm, or any range between any of these thicknesses. The total thickness of adhesive layer 106 may be about 3 μm, 5 μm, 6 μm, 8 μm, 10 μm, 12 μm, 15 μm, 20 μm, 25 μm, 30 μm, 35 μm, 40 μm, 45 μm, 50 μm, 55 μm, 60 μm, 65 μm, 70 μm, 75 μm, or any range between any of these thicknesses.The combined thickness of adhesive layers 104 and 106 may be in the range of 12 μm, 15 μm, 20 μm, 25 μm, 30 μm, 35 μm, 40 μm, 45 μm, 50 μm, 55 μm, 60 μm, 65 μm, 70 μm, 75 μm, 80 μm, 85 μm, 90 μm, 95 μm, 100 μm, 110 μm, 120 μm, 130 μm, 140 μm, or 150 μm, or any range between any of these thicknesses.

[0029] The adhesive layer 106 does not contain any significant amount of flame retardant. The adhesive layer 106 may include acrylic adhesives, natural rubber, synthetic rubber, silicone, polyester, polyolefin, rosin, and epoxy adhesive resins (without being limited to these common pressure-sensitive adhesive resins), as well as combinations thereof. Flame retardant additives can have the effect of reducing adhesion. However, this can be very important for meeting flammability requirements. By including an adhesive layer with a flame retardant additive (adhesive layer 104) and an adhesive layer without a flame retardant additive (layer 106), the present disclosure can meet flammability standards and maintain the required adhesive performance, including both peel and adhesion.

[0030] As shown in FIG. 1 , the film structure 100 is applied to a substrate 108. While the substrate 108 is shown as a horizontal substrate in FIG. 1 , the substrate 108 may be horizontal, vertical, at any angle, or curved. The substrate 108 may be, for example, an interior or exterior wall of a building or structure. The substrate 108 may also be a vehicle, such as a tractor trailer or a train or an airplane. In some cases, a primer may be used to increase adhesion between the film structure 100 and the substrate 108.

[0031] FIG. 2 shows a film structure 200 having three adhesive layers. In FIG. 2, film layer 202 may be made of the same material as film layer 102 in FIG. 1. Adhesive layer 203 is adjacent to film layer 202 and also adjacent to adhesive layer 204. Adhesive layer 206 is adjacent to the opposite side of adhesive layer 204 and contacts substrate 208 to which film structure 200 may be applied. In this case, adhesive layer 204 may be made of the same material as adhesive layer 104 in FIG. 1. Adhesive layers 203 and 206 may be made of the same material as adhesive layer 106. Flame retardant additive 205 may be of the same material as flame retardant additive 105. The thickness range of adhesive layer 204 may be 8 μm, 10 μm, 12 μm, 15 μm, 20 μm, 25 μm, 30 μm, 35 μm, 40 μm, 45 μm, 50 μm, 55 μm, 60 μm, 65 μm, 70 μm, 75 μm, or any range between any of these thicknesses. The thickness range of adhesive layer 203 may be 3 μm, 5 μm, 6 μm, 8 μm, 10 μm, 12 μm, 15 μm, 20 μm, 25 μm, 30 μm, 35 μm, 40 μm, 45 μm, 50 μm, 55 μm, 60 μm, 65 μm, 70 μm, and 75 μm, or any range between any of these thicknesses. The adhesive layer 206 may range in thickness from 3 μm, 5 μm, 6 μm, 8 μm, 10 μm, 12 μm, 15 μm, 20 μm, 25 μm, 30 μm, 35 μm, 40 μm, 45 μm, 50 μm, 55 μm, 60 μm, 65 μm, 70 μm, and 75 μm, or any range between any of these thicknesses. The total thickness range of all three adhesive layers may be 14 μm, 17 μm, 20 μm, 25 μm, 30 μm, 35 μm, 40 μm, 45 μm, 50 μm, 55 μm, 60 μm, 65 μm, 70 μm, 75 μm, 80 μm, 85 μm, 90 μm, 95 μm, 100 μm, 110 μm, 120 μm, 130 μm, 140 μm, or 150 μm, 175 μm, 200 μm, 225 μm, or any range between any of these thicknesses.

[0032] FIG. 3 shows a film structure 300 with a liner 307. The film structure, including film layer 302, adhesive layer 304, and adhesive layer 306, is very similar to the film structure of FIG. 1, except that FIG. 3 shows the liner adjacent to adhesive liner 307. Film structure 300 is typically sold attached to a liner, allowing customers to remove the liner before applying film structure 300 to a substrate. Liner 307 may have a release coating. In some cases, liner 307 may have a structure that creates posts in adhesive layer 306, allowing for improved sliding of the film structure to facilitate placement during application of film structure 300 to a substrate. Liner 307 may also have ridges that form channels in adhesive layer 306, allowing for easier release of air bubbles that might otherwise be trapped during installation. [Example]

[0033] Examples of film articles were prepared using layered pressure sensitive adhesives that provide good low flammability while also maintaining good adhesion to the substrate.

[0034] These examples are for illustrative purposes only and are not meant to limit the scope of the appended claims. All parts, percentages, ratios, etc. in the examples and elsewhere herein are by weight unless otherwise indicated. The following abbreviations: mm = millimeter, μm = micrometer, mm / min = millimeter / minute, N / in = Newtons per inch, g = gram, kg = kilogram, kgf = kilogram force, phr = percentage, MJ / m 2 = megajoules per square meter, kW / m 2 = kilowatts per square meter is used herein.

[0035] [Table 1]

[0036] Test Method Flammability Test Equipment: Cone calorimeter conforming to ISO5660-1. Substrate: 12.5 mm thick non-combustible plasterboard manufactured by American Gypsum (Dallas, TX). Sample Preparation: Plasterboard was primed using PRIMER at 10 g solids per square meter to promote adhesion and allowed to dry at room temperature. The polyester release liner was peeled from the adhesive side of the film article and the film article was adhered to the primed plasterboard using a flat plastic squeegee to remove air bubbles. Flammability acceptance criteria: THR = 8 MJ / m, measured over 20 minutes 2 The total heat loss is: FIGRA = Fire Growth Rate = 8KW / (m 2* s) or less. FIGRA is the peak heat release rate (KW / (m 2 )) divided by the time to peak.

[0037] 180 peel adhesion test Equipment: Tensilon RTG series tensile testing machine manufactured by A&D Co., Ltd. (Japan). Substrate: Bonded steel sheet manufactured by MSC Industrial Supply (Melville, NY). Temperature: 20℃, room temperature. Aging time: The film was laminated onto the substrate and then peeled off 48 hours later. Sample preparation: 25mm x 150mm film article samples were laminated to the substrate with a 1 kg weighted roller. The substrate was cleaned by wiping with isopropyl alcohol prior to lamination. Testing: After aging, the samples were peeled from the substrate at a 180 degree angle at a rate of 300 mm / min. Three samples were tested and averaged for each condition. Results are reported in N / in. Peel adhesion strength tolerance: 20N / in or more.

[0038] Loop tack adhesive strength test Equipment: Tensilon RTG series tensile testing machine manufactured by A&D Co., Ltd. (Japan). Base material: vinyl film, film 2. Temperature: 5℃ Sample Preparation: A 25 mm wide by 150 mm long film article sample was bent into a loop (no overlapping ends) with the adhesive on the outside of the loop. Testing: The sample was contacted with the substrate at a speed of 1000 mm / min until a 30 mm length of film was adhered to the substrate. The sample was then immediately peeled from the substrate at a speed of 100 mm / min. Three samples were tested and averaged for each condition. Results are reported in N / in. Loop tack tolerance: 15N / in or more.

[0039] Probe tack adhesion test Equipment: TE-6002 probe tack tester with chamber manufactured by Tester Sangyo Co., Ltd. (Japan) Chamber temperature: 5°C. Sample Preparation: The exposed adhesive side of the film article was tested. Testing: Low temperature tack was measured according to the instrument's instructions. Three samples were tested for each example and the results were averaged. Results are reported in kgf. Probe tack tolerance standard: 2.5 kgf or more.

[0040] Example 1: Two-layer adhesive The calendered PVC film was laminated with two layered adhesives, totaling 38 μm of combined adhesive layer. The inner adhesive layer, the adhesive layer between the film and the outer adhesive layer, was formulated with different percentages of flame-retardant filler, as listed in Table 1. The outer adhesive layer did not contain flame-retardant filler. Comparative examples were made, one without flame-retardant filler (CE1-1) and the other with flame-retardant filler throughout the adhesive (CE1-2).

[0041] CL was added to the acrylic adhesive RESIN at 2.17 phr to formulate each adhesive layer. Each adhesive layer was hand-coated onto the LINER using a notch bar coater, then dried at 65°C for 2 minutes, followed by drying at 95°C for 2 minutes.

[0042] Each adhesive layer was then laminated between rubber nip rollers to Film 1 for adhesion testing or Film 2 for flammability testing, and each liner was removed. Samples for flammability testing, 180° peel adhesion testing, and loop tack testing were prepared as described in the test methods. The results are shown in Table 1.

[0043] [Table 2]

[0044] Example E1-1 has a 65.5% filled inner layer adhesive with a 19 μm flame retardant and a 19 μm unfilled outer layer adhesive. E1-1 passed the total heat release criteria, the 180 peel adhesion test, and the loop tack adhesion test.

[0045] Example E1-2 has a 41.0% filled inner layer adhesive with a 30 μm flame retardant and an 8 μm unfilled outer layer adhesive. E1-2 passed the total heat release criteria, the 180 peel adhesion test, and the loop tack adhesion test.

[0046] Comparative Example CE1-1 has a standard single layer of 38 μm unfilled adhesive. CE1-1 failed the total heat dissipation criteria. However, CE1-1 passed the 180 peel adhesion test and the loop tack adhesion test.

[0047] Comparative Example CE1-2 has a single layer of 38 μm flame retardant-containing adhesive with a 32.8% fill rate. CE1-2 passed the total heat release criteria and the 180° peel adhesion test. However, CE1-2 failed the loop tack adhesion test.

[0048] Example 2: Various flame retardant fillers Calendered PVC film article samples with adhesive layers were prepared as described in Example 1, with the following modifications: different flame retardants were used, as well as thinner adhesive layers, as described in Table 2. Samples for flammability testing, 180-degree peel adhesion, and probe tack were prepared as indicated in the test methods. The results are shown in Table 2.

[0049] [Table 3]

[0050] Examples E2-1 through E2-6 have a 12-30 μm, 50% filled inner adhesive layer and an 8-26 μm unfilled outer adhesive layer with a variety of different flame retardants. Each of E2-1 through E2-6 passed both the THR and FIGRA standards for flammability testing, the 180 peel adhesion test, and the loop tack adhesion test.

[0051] Example 3: Three-layer adhesive Calendered PVC film article samples with adhesive layers were prepared as described in Example 1. As shown in Table 3, Example 3 had a three-layer adhesive consisting of a 25 micron highly 65% ​​filled middle layer adhesive, an additional 6.5 μm unfilled inner layer adhesive, and a 6.5 μm unfilled outer layer adhesive. The unfilled and filled adhesive layers had thicknesses that combined to give a total three-layer adhesive thickness of 38 μm. Samples for flammability testing, 180° peel adhesion, and probe tack were prepared as indicated in the test methods. The results are shown in Table 3.

[0052] [Table 4]

[0053] Example E3, which had three layers of adhesive, passed the THR and FIGRA standards for flammability testing, the 180 peel adhesion test, and the loop tack adhesion test.

[0054] Example 4: Adhesive Layers of Various Thicknesses Calendered PVC film article samples with adhesive layers were prepared as described in Example 1, with the following modifications. Various adhesive layer thicknesses were used, as listed in Table 4. Comparative examples (CE4-1, 2) were prepared as shown in Table 4. Samples for flammability testing and 180-degree peel adhesion were prepared as indicated in the test methods. The results are shown in Table 4.

[0055] [Table 5]

[0056] Examples E4-1, E4-2, and E4-3 had a 50% filled inner layer adhesive with flame retardant of 12-30 μm and an unfilled outer layer adhesive of 6.5-8 μm, for a total adhesive thickness range of 18.5-44.5 μm. Each of E4-1, E4-2, and E4-3 passed the THR standard flammability test and the 180 peel adhesion test.

[0057] Comparative Example CE4-1 has a 6.5 μm flame retardant, 50% filled inner layer adhesive and a 38 μm unfilled outer layer adhesive. CE4-1 failed the THR flammability test but passed the 180 peel adhesion test.

[0058] Comparative Example CE4-2 has a 50% filled inner layer adhesive with 8 μm of flame retardant and a 2 μm unfilled outer layer adhesive. CE4-2 failed the 180 peel adhesion test but passed the THR flammability test.

[0059] Example 5: Various Film Material Layers Film article samples with adhesive layers were prepared as described in Example 1, with the following modifications: Various film materials were used as listed in Table 5. Flammability test samples were prepared as indicated in the test methods. The results are shown in Table 5.

[0060] [Table 6]

[0061] Examples E5-1 through E5-7 have seven different typical film materials, with a 30-34 μm flame retardant-containing 50% filled inner adhesive layer and a 3-8 μm unfilled outer adhesive layer. Each of E5-1 through E5-7 passed the FIGRA and THR flammability tests.

Claims

[Claim 1] a film layer; a first adhesive layer having at least 41 wt. % of a flame retardant additive; a second adhesive layer that does not have a flame retardant additive; Liner and A low flammability film structure comprising, in this order: a total thickness of the first adhesive layer is 32% to 85% of a total thickness of the first adhesive layer and the second adhesive layer, and the film structure has a peel adhesion strength of 20 N or more under a 180° peel adhesion strength test; The total thickness of the first adhesive layer and the second adhesive layer is in the range of 18.5 to 44.5 microns, and the film structure has a flame resistance of 8 MJ / m ２ and the film structure has a total heat dissipation of 8 KW / (m ２＊ s) have a fire growth rate (FIGRA) of less than or equal to the liner is configured to improve sliding of the second adhesive layer against a substrate by forming posts in the second adhesive layer; A film structure wherein the film layer is a graphic film and an ink layer is deposited on the film layer.

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