Polyester film for attaching rubber sheets

Abstract

To provide a polyester film for rubber sheet adhesion that is less prone to blocking and offers superior workability and transportability.SOLUTION: A polyester film for rubber sheet adhesion comprises a polyester film, and a primer layer provided on at least a part of one side or both sides of the polyester film. The primer layer at least comprises nitrile rubber. The nitrile rubber constitutes 50 mass% or more of the total solid of the primer layer.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a polyester film for attaching a rubber sheet.

Background Art

[0002] Since rubber sheets are excellent in elasticity, they are applied to sealing materials, cushioning materials, etc. in a wide range of industrial fields. However, when a rubber sheet is bonded to an adherend through an adhesive, the performance of the adhesive may be deteriorated by the components contained in the rubber. Therefore, conventionally, an adhesive for rubber has been used for rubber sheets. In addition, since rubber sheets have low rigidity, even when bonded to an adherend using an adhesive or the like, depending on the usage state, the rubber sheet may float or peel off. In Patent Document 1, in order to increase the rigidity of a rubber sheet, a laminate in which a rubber layer and a polyester film are firmly joined has been proposed.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] The polyester film described in Patent Document 1 has a polyurethane resin adhesive layer having an unsaturated hydrocarbon bond in the molecule. Then, after laminating an uncrosslinked rubber layer on the surface of the polyurethane resin adhesive layer, crosslinking treatment is performed by irradiating active energy rays. In this crosslinking treatment, as a result of the crosslinking reaction of the rubber layer itself and the crosslinking reaction at the interface between the polyurethane resin adhesive layer and the rubber layer proceeding simultaneously, the rubber layer and the polyester film are firmly joined. However, polyester films themselves, or polyester films coated with resin on at least one side, are prone to blocking. Furthermore, the crosslinking reaction of the rubber layer and integration with the polyester film occur simultaneously. Therefore, the polyester film described in Patent Document 1 is difficult to apply to various rubber sheets.

[0005] The inventors conceived of integrating a laminated sheet, which has a primer layer containing rubber components on a polyester sheet, with a rubber sheet by bonding the laminated sheet to the rubber sheet. Integrating the laminated sheet and the rubber sheet improves the rigidity of the rubber sheet. Furthermore, various rubber sheets can be attached to the polyester sheet used in the laminated sheet. However, when prototype laminated sheets with a primer layer containing rubber components were actually fabricated, the primer layer containing rubber components sometimes exhibited tackiness. As a result, blocking occurred between sheets when they were stacked or when they were wound up, leading to problems with workability and transportability. Therefore, the present invention provides a polyester film for attaching rubber sheets that is less prone to blocking and has excellent workability and transportability. [Means for solving the problem]

[0006] The present invention has the following aspects. [1] A polyester film for attaching rubber sheets, comprising: a polyester film; a primer layer provided on at least a portion of one or both sides of the polyester film; the primer layer containing at least nitrile rubber; and the proportion of nitrile rubber being 50% by mass or more of the total solid content of the primer layer. [2] The polyester film for attaching rubber sheets according to [1], wherein the primer layer further comprises at least one selected from the group consisting of chloroprene rubber and polyester resin. [3] The polyester film for attaching rubber sheets according to [1] or [2], wherein the surface of the polyester film that is in contact with the primer layer is treated with an easy-adhesion treatment. [Effects of the Invention]

[0007] According to the present invention, a polyester film for attaching rubber sheets is provided that is less prone to blocking and has excellent workability and transportability. [Modes for carrying out the invention]

[0008] In this specification, the "~" symbol indicating a numerical range means that the numbers before and after it are included as the lower and upper limits, respectively. The lower and upper limits of the numerical ranges disclosed herein can be combined in any way to create new numerical ranges.

[0009] <Polyester film for attaching rubber sheets> The polyester film for laminating rubber sheets of the present invention comprises a polyester film and a primer layer provided on at least a portion of one or both sides of the polyester film. The polyester film for laminating rubber sheets of the present invention is used by laminating it with a rubber sheet or an article having a rubber sheet. The term "rubber sheet" as used herein also includes elastomer sheets.

[0010] The primer layer may be provided on only one side of the polyester film, or on both sides. In either case, it is sufficient that the primer layer is provided on at least a portion of the area when viewed in plan. That is, the primer layer may be provided on a part of the surface of the polyester film, or it may be provided on the entire surface of the polyester film. In terms of adhesion to the rubber sheet and adhesive durability, it is preferable that the primer layer is provided on the entire surface of the polyester film.

[0011] The following describes an example of an embodiment of a polyester film for rubber sheet application. The following description is a disclosure of several embodiments and representative examples, and the present invention is not limited to the following description.

[0012] (Polyester film) Polyester films are not particularly limited as long as they contain polyester. Various polyester films can be used. Examples of polyesters include polyethylene terephthalate, polyethylene naphthalate, polybutylene terephthalate, polybutylene naphthalate, and polylactic acid. Polyester may be used alone or in combination of two or more types.

[0013] The polyester film may have other carboxylic acid units and other alcohol units, as long as they do not impair the effects of the invention. Other carboxylic acids include, for example, isophthalic acid, phthalic acid, 2,6-naphthalenedicarboxylic acid, 5-sodium sulfisoisophthalic acid, oxalic acid, succinic acid, adipic acid, sebacic acid, azelaic acid, dodecanedioic acid, dimer acid, maleic anhydride, maleic acid, fumaric acid, itaconic acid, citraconic acid, mesaconic acid, dicarboxylic acids such as cyclohexanedicarboxylic acid, 4-hydroxybenzoic acid, ε-caprolactone, and lactic acid. These other carboxylic acids may be used individually or in combination of two or more. Other alcohols include, for example, ethylene glycol, diethylene glycol, 1,3-propanediol, neopentyl glycol, 1,6-hexanediol, cyclohexanedimethanol, triethylene glycol, polyethylene glycol, polypropylene glycol, polytetramethylene glycol, ethylene oxide adducts of bisphenol A, and ethylene oxide adducts of bisphenol S. Other examples include trifunctional compounds such as trimellitic acid, trimesic acid, pyromellitic acid, trimethylolpropane, glycerin, and pentaerythritol. Other alcohols may be used individually or in combination of two or more.

[0014] The polyester film may contain inorganic fine particles and organic fine particles in order to improve the handling properties of the film. Further, the polyester film may contain various additives as required. Examples of the additives for the polyester film include wax, antioxidant, antistatic agent, plasticizer, crystal nucleating agent, viscosity reducer, heat stabilizer, pigment for coloring, anti-coloring agent, and ultraviolet absorber. The additives may be used singly or in combination of two or more.

[0015] The polyester film may be subjected to an easy adhesion treatment or may be an untreated one without an easy adhesion treatment. In terms of improving the adhesiveness with the primer layer, it is preferable that an easy adhesion treatment is applied to the surface in contact with the primer layer. The easy adhesion treatment is not particularly limited, and examples thereof include corona discharge treatment, plasma treatment, and anchor coat formation treatment.

[0016] The polyester film may be a stretched film or an unstretched film. In the case of a stretched film, the polyester film may be a uniaxially stretched film or a biaxially stretched film. Depending on the use of the polyester film for rubber sheet adhesion, an unstretched film, a uniaxially stretched film, or a biaxially stretched film may be appropriately selected and used.

[0017] The thickness of the polyester film is not particularly limited. The thickness of the polyester film may be appropriately changed or set according to the use of the polyester film for rubber sheet adhesion. When the polyester film for rubber sheet adhesion is applied to waterproof equipment, the thickness of the polyester film is preferably 9 to 75 μm, more preferably 12 to 50 μm, and even more preferably 16 to 38 μm. When the thickness of the polyester film is not less than the lower limit value within the above numerical range, the rigidity is likely to be improved. When the thickness of the polyester film is not more than the upper limit value within the above numerical range, the productivity is likely to be improved. The thickness of the polyester film can be measured using a thickness measuring instrument.

[0018] As the polyester film, commercially available products may be used. Examples of commercially available products of polyester films include "Emblet" manufactured by Unitika, "Ester Film" manufactured by Toyobo, "Cosmo Shine" manufactured by Toyobo, "Lumirror" manufactured by Toray, "Diafoil" manufactured by Mitsubishi Chemical, and "Polyester Film" by SKC.

[0019] (Primer layer) The primer layer is provided on one or both sides of the polyester film. The primer layer contains at least nitrile rubber. By containing nitrile rubber as a rubber component, blocking can be reduced while maintaining good adhesiveness with the rubber sheet.

[0020] Nitrile rubber is typically a copolymer of at least one α,β-unsaturated nitrile and at least one conjugated diene. Examples of α,β-unsaturated nitriles include acrylonitrile, methacrylonitrile, α-chloronitrile, and α-cyanoethyl acrylonitrile. One kind of α,β-unsaturated nitrile may be used alone, or two or more kinds may be used in combination. Examples of conjugated dienes include 1,3-butadiene, 2,3-dimethyl-1,3-butadiene, 2-ethyl-1,3-butadiene, and 1,3-pentadiene. One kind of conjugated diene may be used alone, or two or more kinds may be used in combination. The nitrile rubber may further have other monomer units copolymerizable with α,β-unsaturated nitrile and conjugated diene. One kind of other monomer may be used alone, or two or more kinds may be used in combination.

[0021] The primer layer may further contain other rubbers other than nitrile rubber. Examples of other rubbers include chloroprene rubber, natural rubber, silicone rubber, ethylene propylene diene rubber, acrylic rubber, and fluorine rubber. Among them, chloroprene rubber is preferable in terms of easily obtaining excellent adhesive durability even in an environment such as outdoors. One kind of other rubber may be used alone, or two or more kinds may be used in combination.

[0022] As the chloroprene rubber, commercially available chloroprene rubber adhesives may be used. Examples include Cemedyne's "575F," Mitsuboshi Belting's "Neo-Bond R," and Konishi's "Heat-Resistant Brush-On HG."

[0023] The primer layer may further contain other resins besides nitrile rubber and other rubbers. The other resins are not particularly limited as long as they are resins that can be used in combination with nitrile rubber and have low tackiness. Examples include polyester resins, acrylic resins, phenolic resins, and polyurethane resins. Among these, polyester resins are preferred in terms of improving adhesion with the polyester film. Other resins may be used individually or in combination of two or more.

[0024] Other commercially available resins may be used. Examples of other commercially available resins include Toyo Morton's "AD-76H5" (polyester resin) and Tosoh's "Nipporan 3228" (polyester-based polyurethane resin).

[0025] The primer layer may further contain other components as optional components besides nitrile rubber, other rubbers, and other resins. If the primer layer contains other components, these other components may be added insofar as they do not impair the effects of the present invention. Other components of the primer layer include various additives such as pigments, dyes, antioxidants, antistatic agents, and flame retardants. However, the other components are not limited to these examples. Each of the other components may be used individually or in combination of two or more.

[0026] The amount of primer layer applied is not particularly limited. It can be appropriately changed or set depending on the application of the polyester film for rubber sheet application. When the polyester film for rubber sheet application is used for outdoor waterproofing equipment, the amount of primer layer applied is 0.5 to 4.0 g / m². 2 Preferably, 0.5 to 2.0 g / m 2More preferably, 0.8~1.5g / m 2 This is even more preferable. If the amount of primer layer applied is above the lower limit of the aforementioned numerical range, adhesion to the rubber sheet tends to improve. If the amount of primer layer applied is below the upper limit of the aforementioned numerical range, it is advantageous in terms of cost reduction. The amount of primer applied is the amount after drying and can be determined by weight measurement.

[0027] The proportion of nitrile rubber is 50% by mass or more relative to the total solid content of the primer layer, preferably 50 to 100% by mass, more preferably 60 to 95% by mass, and even more preferably 70 to 95% by mass. If the proportion of nitrile rubber is above the lower limit of the above numerical range, blocking resistance is improved. If the proportion of nitrile rubber is below the upper limit of the above numerical range, the adhesive durability to the rubber sheet tends to improve. Here, the total solid content of the primer layer is the sum of nitrile rubber, other rubbers, other resins, and other components, and the same applies in the following explanation.

[0028] The proportion of other rubber is preferably 0 to 50% by mass, more preferably 5 to 40% by mass, and even more preferably 5 to 30% by mass, relative to the total solid content of the primer layer. When the proportion of other rubber is above the lower limit of the above numerical range, the adhesion to the adhesive used in the rubber sheet is excellent. When the proportion of other rubber is below the upper limit of the above numerical range, the occurrence of blocking in the primer layer is easily suppressed.

[0029] The proportion of other resins is preferably 0 to 20% by mass, more preferably 0 to 10% by mass, and even more preferably 0 to 5% by mass, relative to the total solid content of the primer layer. If the proportion of other resins is above the lower limit of the above numerical range, the properties of the other resins are more likely to be expressed in the primer layer. If the proportion of other resins is below the upper limit of the above numerical range, tackiness of the primer layer is less likely to occur.

[0030] In one preferred example, the primer layer further comprises at least one selected from the group consisting of chloroprene rubber and polyester resin. In yet another example, the primer layer may comprise both chloroprene rubber and polyester resin.

[0031] (Manufacturing method) The method for manufacturing a polyester film for attaching rubber sheets is not particularly limited. For example, one method involves applying a coating solution, in which a rubber component containing at least nitrile rubber is dissolved in a solvent, to one or both sides of a polyester film, and then removing the solvent. The rubber component may also contain other rubbers, resins, or other components as needed.

[0032] The solvent is not particularly limited as long as it can dissolve the rubber component. Examples include aliphatic hydrocarbons such as n-hexane and heptane; aromatic hydrocarbons such as toluene and xylene; alcohols such as methanol, ethanol, isopropyl alcohol, and butanol; ketones such as acetone and methyl ethyl ketone; esters such as ethyl acetate and butyl acetate; and ethers such as tetrahydrofuran and ethylene glycol monobutyl ether. However, the solvents are not limited to these examples. Furthermore, a single solvent may be used, or two or more solvents may be used in combination.

[0033] The method for removing the solvent after application of the coating solution is not particularly limited, but heat drying is preferred. Heating promotes crosslinking, further improving blocking resistance. By removing the solvent after application of the coating solution, a primer layer containing nitrile rubber is provided on at least a portion of one or both sides of the polyester film.

[0034] (Mechanism of action) The polyester film for attaching rubber sheets according to the present invention has a primer layer containing at least nitrile rubber, wherein the proportion of nitrile rubber is 50% by mass or more of the total solid content of the primer layer. Therefore, blocking can be reduced while maintaining good adhesion with the rubber sheet in the primer layer. As a result, the polyester film for attaching rubber sheets according to the present invention makes it less likely for blocking to occur when sheets are stacked or when sheets are wound up, resulting in excellent workability and transportability.

[0035] <Application> The polyester film for laminating rubber sheets of the present invention is used in combination with rubber sheets or articles having rubber sheets. The rubber sheet is not particularly limited, but for example, in the case of a waterproof sheet, a vulcanized rubber sheet mainly made of ethylene propylene rubber (EPDM) or butyl rubber as exemplified in JIS A6008 can be used. Rubber-based adhesives can be suitably used as the adhesive for bonding. For example, chloroprene-based rubber adhesives are available. A commercially available example of such adhesive is Neo-Bond R (manufactured by Mitsuboshi Belting Co., Ltd.). [Examples]

[0036] The present invention will be specifically described below with reference to examples, but the present invention is not limited to the following description.

[0037] <Raw materials> (Polyester film) • S-25: Corona-treated polyester film (Unitika Corporation product, 25 μm thickness) • V540: Easy-adhesion treated polyester film (SKC product, 23μm thickness)

[0038] (Rubber component) • Rubber 1: Acrylonitrile-butadiene copolymer composition (Tg=-10℃) • 575F: Chloroprene rubber adhesive (Cemedine Co., Ltd. product "575F") • Neo-Bond®: Chloroprene rubber-based adhesive (Mitsuboshi Belting Co., Ltd. product "Neo-Bond®")

[0039] (Other resins) • AD-76H5: Polyester resin (Toyo Morton Co., Ltd. product "AD-76H5") ·3228: A mixture obtained by adding 14 parts of Coronate L (a Tosoh product) in terms of solid content to 100 parts of polyester polyurethane resin (Tosoh product "Nipporan 3228").

[0040] (Other ingredients) • Nocrack 224: Anti-aging agent (Nocrack 224, a product of Ouchi Shinko Chemical Industry Co., Ltd.)

[0041] <Example 1> (Preparation of coating solution for the primer layer) A coating solution was prepared by diluting an acrylonitrile-butadiene copolymer composition (Tg=-10℃) with toluene to a solid content concentration of 10%. The prepared coating solution was applied to one side of the polyester film using a Meyer bar, dried at 100°C for 90 seconds, and the coating amount was 1.0 g / m². 2 A primer layer was then applied to obtain the polyester film for attaching rubber sheets as in Example 1.

[0042] <Examples 2-8, Comparative Examples 1-4> Polyester films for attaching rubber sheets were obtained in the same manner as in Example 1, except that the solid content composition of the coating solution was changed as shown in Table 1.

[0043] [Table 1]

[0044] <Evaluation of blocking resistance> (Measurement of peel-off adhesive strength) Two polyester films for attaching rubber sheets were prepared for each example. Using these pairs of polyester films for attaching rubber sheets, the surface of the primer layer and the surface of the polyester film were bonded together at a temperature of 40°C and a load of 0.3 kgf / cm². 2 The layers were then pressed and bonded for 24 hours. After that, the adhesive strength was measured according to the T-type release method specified in JIS K6854-3. Specifically, after bonding under the above conditions, the peel adhesive strength between the surface of the primer layer and the surface of the polyester film was measured at a tensile speed of 300 mm / min.

[0045] (Evaluation Criteria) The evaluation criteria for blocking resistance are as follows: A and B are considered compliant. A: The peel-off adhesive strength is less than 3 gf / 25 mm. It has particularly excellent blocking resistance. B: The peel-off adhesive strength is 3gf / 25mm or more and less than 5gf / 25mm. There is some blocking, but it does not pose a practical problem. C: The peel adhesive strength is 5gf / 25mm or more and less than 10gf / 25mm. This causes blocking, which presents some practical problems. D: The peeling adhesive strength is 10gf / 25mm or higher. Blocking is severe, which poses practical problems.

[0046] <Evaluation of adhesive durability> (Preparation of adhesive samples) For each example, apply 250g / m² of Neo-Bond R (manufactured by Mitsuboshi Belting Co., Ltd.), a rubber-based adhesive, evenly to the surface of the primer layer of the polyester film used for attaching the rubber sheet, using a brush. 2 It was applied, and then allowed to air dry for 60 minutes. On the other hand, apply 100g / m² of Neo-Bond R rubber adhesive evenly to one side of the Neo-Roofing E rubber sheet (manufactured by Mitsuboshi Belting Co., Ltd.) using a brush. 2 It was applied, and then allowed to air dry for 60 minutes. Next, the polyester film for attaching the rubber sheet and the rubber sheet, each coated with rubber-based adhesive, were laminated together, and a load was applied using a hand roller. After curing at room temperature for two days, the bonded rubber sheet was cut to a size of 25 mm x 100 mm to serve as a test sample. This test sample is a laminate in which the polyester film, primer layer, rubber-based adhesive layer, and rubber sheet are laminated in that order.

[0047] (Heat resistance test treatment) The above test samples were heated at 80°C for 30 or 60 days. Afterward, they were allowed to cool at room temperature for 2 hours to obtain heat-resistant test samples.

[0048] (Water resistance test treatment) The above test samples were placed in a sealed container with distilled water and stored in a 40°C constant temperature bath for 30 or 60 days. After that, the samples were removed from the container, wiped to remove moisture, and allowed to cool at room temperature for 2 hours to obtain the water resistance test treated samples.

[0049] (Measurement of adhesive strength) The above heat-resistant or water-resistant samples were subjected to adhesive strength tests in accordance with the T-peel test specified in JIS K6854-3. Specifically, the T-peel adhesive strength between the primer-coated film and the rubber sheet was measured at a tensile speed of 200 mm / min, and the peel location was also determined. The peel locations were classified as follows: X: Delamination occurred at the interface between the polyester film and the primer layer. Y: Delamination occurred at the interface between the primer layer and the rubber-based adhesive layer. Z: Delamination occurred at the interface between the rubber-based adhesive layer and the rubber sheet.

[0050] (Evaluation Criteria) The criteria for evaluating adhesive strength are as follows: ○: The adhesive strength is 10N / 25mm or higher. △: The adhesive strength is 6N / 25mm or more and less than 10N / 25mm. ×: The adhesive strength is less than 6N / 25mm.

[0051] <Judgment> The polyester film used for attaching rubber sheets in each example was evaluated according to the following criteria. A rating of ○ or △ was considered to be practically acceptable. Judgment ○: Blocking resistance evaluation is A or B, and all adhesive durability evaluations are ○. Judgment △: Blocking resistance evaluation is A or B, and there is a △ in the adhesive durability evaluation, but no ×. Judgment ×: The blocking resistance evaluation is C or D, or the adhesive durability evaluation is ×.

[0052] [Table 2]

[0053] The polyester films for rubber sheet application in Examples 1-8 did not exhibit tackiness. This result confirmed that polyester films for rubber sheet application were obtained that were less prone to blocking and possessed excellent workability and transportability. Furthermore, in Examples 2-8, where chloroprene rubber or polyester resin was incorporated into the coating solution, excellent adhesive durability was also confirmed. However, Examples 1, 3, and 5 are for reference only. [Industrial applicability]

[0054] According to the present invention, a polyester film for attaching rubber sheets is provided that is less prone to blocking and has excellent workability and transportability.

Claims

1. Polyester film and A primer layer provided on at least a portion of one or both sides of the polyester film, It has, The primer layer comprises at least nitrile rubber and chloroprene rubber. The proportion of the nitrile rubber is 50% by mass or more relative to the total solid content of the primer layer. A polyester film for attaching rubber sheets, wherein the proportion of chloroprene rubber is 5 to 30% by mass relative to the total solid content of the primer layer.

2. The polyester film for attaching rubber sheets according to claim 1, wherein the primer layer further comprises at least one selected from the group consisting of polyester resins.

3. The polyester film for attaching rubber sheets according to claim 1 or 2, wherein the surface of the polyester film that is in contact with the primer layer is subjected to an easy-adhesion treatment.

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