KR102123625B1 - Polymer film - Google Patents

Abstract

The present invention is a polyamide resin; A copolymer comprising a polyamide-based segment and a poly-ether-based segment; And olefin-based polymer compound; including a base film containing, relates to a polymer film for an inner liner.

Description

Polymer film {POLYMER FILM}

The present invention relates to a polymer film and a pneumatic tire, and more specifically, to realize an excellent airtightness even with a thin thickness, to reduce the weight of the tire and improve the fuel efficiency of the vehicle, and to improve the mechanical properties such as high durability and fatigue resistance with excellent formability. A polymer film for an inner liner having physical properties and a pneumatic tire including the polymer film for the inner liner.

The tire is responsible for supporting the load of the vehicle, alleviating the impact from the road surface, and transmitting the driving or braking force of the vehicle to the ground. Generally, a tire is a composite of fiber/steel/rubber, and generally has a structure as shown in FIG. 1.

Tread (1): It is the part that comes into contact with the road surface and must provide the frictional force necessary for braking and driving, must have good abrasion resistance, be able to withstand external shocks and have little heat generation.

Body Ply (or Carcass) (6): A layer of cord inside the tire that supports the load, withstands shock and must have strong fatigue resistance against rolling motions while driving.

Belt (5): It is located between the body plies, and is composed of steel wire in most cases. It not only relieves external shocks, but also maintains a wide ground surface of the tread to improve driving stability.

Side Wall (3): refers to the rubber layer between the bead (9) from the lower part of the shoulder (2) and serves to protect the body ply (6) inside.

Inner Liner (7): It is located inside the tire instead of the tube to prevent air leakage, allowing pneumatic tires.

BEAD (9): This is a square or hexagonal wire bundle with rubber coated on the wire, which serves to secure and secure the tire to the rim.

CAP PLY (4): This is a special cord paper located on the belt of a radial tire for some passenger cars, minimizing the movement of the belt when driving.

APEX (8): This is a triangular rubber filler used to minimize bead dispersion and to mitigate external impacts to protect beads and prevent air ingress during molding.

Recently, tube-less tires in which high-pressure air of about 30 to 40 psi is injected are usually used without using a tube, to prevent the inside air from leaking to the outside during vehicle driving. To this end, an inner liner having high airtightness is disposed on the inner layer of the carcass.

Previously, tire innerliners having rubber components such as butyl rubber or halobutyl rubber, which are relatively low in air permeability, were used. In these innerliners, the content of the rubber or the thickness of the innerliner had to be increased to obtain sufficient airtightness. . However, when the content of the rubber component and the tire thickness increase, the total weight of the tire increases and the fuel efficiency of the vehicle decreases.

In addition, the rubber components have a relatively low heat resistance, so that an air pocket is generated between the inner rubber and the inner liner of the carcass layer during the vulcanization process of the tire or the driving process of the car, which repeatedly undergoes deformation at high temperature conditions, or the inner liner There was a problem that the shape and physical properties are changed. In addition, in order to combine the rubber components with the curcus layer of the tire, a vulcanizing agent or a vulcanization process had to be applied, and it was difficult to secure sufficient adhesive force.

Accordingly, various methods have been proposed to reduce the fuel efficiency by reducing the thickness and weight of the inner liner, and to reduce changes in the shape or physical properties of the inner liner generated during the tire forming or driving process.

However, any previously known method has limitations in maintaining excellent air permeability and tire formability while sufficiently reducing the thickness and weight of the inner liner. In addition, the inner liner obtained by a method known in the prior art has its own physical properties deteriorated or cracks in the film, etc. This phenomenon appeared.

The present invention is to provide a polymer film for an inner liner that has excellent airtightness even with a thin thickness, thereby reducing the weight of a tire and improving the fuel efficiency of a vehicle, and having excellent moldability and mechanical properties such as high durability and fatigue resistance.

In addition, the present invention is to provide a pneumatic tire including the polymer film for the inner liner.

In this specification, a polyamide-based resin; A copolymer comprising a polyamide-based segment and a poly-ether-based segment; And an olefin-based polymer compound; including a base film, a polymer film for an inner liner is provided.

In addition, in this specification, a pneumatic tire including the polymer film for the inner liner is provided.

Hereinafter, a polymer film for an inner liner and a pneumatic tire according to a specific embodiment of the present invention will be described in more detail.

According to one embodiment of the invention, a polyamide-based resin; A copolymer comprising a polyamide-based segment and a poly-ether-based segment; And an olefin-based polymer compound; including a base film, a polymer film for an inner liner may be provided.

As a result of the research of the present inventors, when a base film containing the polyamide resin, the copolymer containing the specific segments, and the olefin-based polymer compound is used, light weight is achieved by realizing excellent airtightness even with a thin thickness and fuel economy of the vehicle. It can be improved, and it has been confirmed that a polymer film for an inner liner having high heat resistance and excellent mechanical properties such as high durability and fatigue resistance along with excellent moldability can be provided.

In particular, when a previously known polymer resin film or a film containing a polymer component is used as an inner liner, cracks in the inner liner itself may occur due to external shocks, deformations or high temperature effects that occur during tire manufacturing or automobile driving. Frequent occurrences or breakage of the inner liner occurred.

On the contrary, the base film uses the olefinic polymer compound together with a copolymer comprising the polyamide-based resin and a polyamide-based segment and a poly-ether-based segment, and the innerliner of the embodiment. It is possible to prevent the phenomenon that the polymer film for crystallization is caused by high temperature or external impact or deformation, and also maintain the other mechanical properties of the polymer film for the inner liner at an equal level or higher, while lowering the modulus properties or increasing the elasticity, thereby improving fatigue resistance. And durability.

Specifically, the olefin-based polymer compound serves to increase the softness of the base film and to improve the ability to absorb shock applied from the outside, and also to significantly lower the modulus of the base film while being able to significantly lower the base film It is possible to prevent the phenomenon of crystallization by changing the internal structure of the compound or polymer contained in.

The base film may include 1% to 40% by weight of the olefinic polymer compound, or 3% to 35% by weight. If the content of the olefin-based polymer compound is too small, the degree of action and effect according to the olefin-based polymer compound may be negligible. In addition, if the content of the olefin-based polymer compound is too large, physical properties or effects expressed from the polyamide-based resin and the copolymer may be reduced, and the polymer film for the inner liner of the one embodiment is applied to mold during tire production. Sex may degrade.

The olefin-based polymer compound may include an olefin-based polymer, an olefin-based copolymer, dicarboxylic acid or an olefin-based polymer or copolymer grafted with an acid anhydride, or a mixture of two or more thereof.

The olefin-based polymer may include polyethylene, polypropylene, polystyrene, or mixtures thereof.

The olefin-based copolymer may include ethylene-propylene copolymer or ethylene-styrene copolymer.

As described above, the olefin-based polymer compound may include an olefin-based polymer or copolymer grafted with dicarboxylic acid or an acid anhydride thereof, wherein the dicarboxylic acid is maleic acid, phthalic acid, itaconic acid, citraconic acid , Alkenylsuccinic acid, cis-1,2,3,6 tetrahydrophthalic acid, 4-methyl-1,2,3,6 tetrahydrophthalic acid or a mixture of two or more thereof, the dicarboxylic acid The dianhydride of may be the dicarboxylic acid dianhydride of the above-described example.

The content of the grafted dicarboxylic acid or its acid anhydride in the olefin-based polymer or copolymer in which the dicarboxylic acid or its acid anhydride is grafted may be 0.05% by weight or more, specifically 0.05% by weight to 5% by weight Or 0.1% to 3% by weight.

The grafting ratio of the dicarboxylic acid or its acid anhydride can be measured from the results obtained by acid-base titration of the olefinic polymer compound. For example, about 1 g of the olefinic polymer compound was added to 150 ml of xylene saturated with water, refluxed for about 2 hours, and then a small amount of 1% by weight thymol blue-dimethylformamide solution was added, and 0.05N sodium hydroxide-ethyl alcohol solution was added. After titration with a little excess to obtain an ultramarine blue solution, the solution was back-titrated until a yellowish color with 0.05N hydrochloric acid-isopropyl alcohol solution was obtained to obtain an acid value, from which dicarboxylic acid grafted to the olefinic polymer compound The amount of acid can be calculated.

The olefin-based polymer compound may have a density of 0.820 g/cm 3 to 0.960 g/cm 3, or 0.840 g/cm 3 to 0.900 g/cm 3.

On the other hand, the polymer film for the innerliner of the embodiment includes the polyamide-based resin and a copolymer comprising the polyamide-based segment and the polyether-based segment, and is relatively low with excellent airtightness. It can have a modulus. Specifically, due to the intrinsic molecular chain properties of the polyamide-based resin contained in the base film, the polymer film for the inner liner of the embodiment is 10 to 20 times the airtightness at about the same thickness compared to butyl rubber commonly used in tires. It may represent, the copolymer is present in a state of being bonded or dispersed between the polyamide-based resins, it is possible to further lower the modulus of the base film, it is possible to suppress the increase in the rigidity of the base film, It can prevent crystallization at high temperature.

When the polymer film for the inner liner is produced by using the polaramide-based resin alone, due to high modulus characteristics, it cannot be sufficiently expanded in the elongation process applied during tire production, and the film is continuously repetitively deformed during the vehicle driving process. As it is concentrated as a part of, crack or breakage may occur in the inner liner.

In addition, when a polymer film for an inner liner is produced by using a copolymer containing the polyamide-based segment and a polyether-based segment alone, the inner liner to be manufactured may not be able to secure sufficient heat resistance. It is easy to thermally decompose even at low temperatures or to easily break in the polymer chain, and the elasticity of the inner liner film produced by cutting of the polymer chain may decrease or crystallinity due to heat may increase significantly, thereby manufacturing tires. Cracks or fractures can be more noticeable in the process or in the process of driving a car.

The polyamide-based resin may have a relative viscosity (96% solution of sulfuric acid) of 3.0 to 4.0, preferably 3.2 to 3.6. When the viscosity of the polyamide-based resin is less than 3.0, sufficient elongation is not secured due to a decrease in toughness, and thus damage may occur during tire manufacturing or automobile operation, and the airtightness or molding that the base film should have as an innerliner polymer film. It may be difficult to secure properties such as a castle. In addition, when the viscosity of the polyamide-based resin exceeds 4.0, the modulus or viscosity of the base film to be produced may be unnecessarily high, and the tire innerliner may be difficult to have proper moldability or elasticity.

The relative viscosity of the polyamide resin refers to a relative viscosity measured using a 96% sulfuric acid solution at room temperature. Specifically, after preparing a measurement solution of two or more by dissolving a specimen of a certain polyamide-based resin (for example, a specimen of 0.025 g) in a 96% solution of sulfuric acid at different concentrations (for example, a polyamide-based resin specimen) Dissolve in 96% sulfuric acid to make concentrations of 0.25 g/dL, 0.10 g/dL and 0.05 g/dL in three measurement solutions), and the relative viscosity of the measurement solution using a viscosity tube at 25° C. (for example, , The ratio of the average passage time of the measurement solution to the passage time of the viscosity tube of the 96% solution of sulfuric acid) can be obtained.

As a polyamide-based resin that can be used for the base film, a polyamide-based resin, for example, a copolymer of nylon 6, nylon 66, nylon 46, nylon 11, nylon 12, nylon 610, nylon 612, nylon 6/66, Nylon 6/66/610 copolymer, nylon MXD6, nylon 6T, nylon 6/6T copolymer, nylon 66/PP copolymer and nylon 66/PPS copolymer; Or N-alkoxyalkylates thereof, for example 6-nylon methoxymethylate, 6-610-nylon methoxymethylate or 612-nylon methoxymethylate, nylon 6, nylon 66, nylon It is preferred to use 46, nylon 11, nylon 12, nylon 610 or nylon 612.

In addition, the polyamide-based resin may be included in the base film by preparing a base film using a monomer of the polyamide-based resin or a precursor of the polyamide-based resin, as well as a method using the resin itself.

Meanwhile, the weight average molecular weight based on Polystyrene may be 50,000 to 500,000, or 70,000 to 300,000, or 90,000 to 200,000, analyzed by GPC of the copolymer containing the polyamide-based segment and the polyether-based segment. If the weight average molecular weight of the copolymer is less than 50,000, the base film to be produced may not be able to secure sufficient mechanical properties for use in the polymer film for the inner liner, and the polymer film for the inner liner ensures a sufficient gas barrier. It can be difficult to do. In addition, when the absolute weight average molecular weight of the copolymer exceeds 500,000, the modulus or crystallinity of the base film increases excessively when heated to a high temperature, and thus it may be difficult to secure an elasticity or elastic recovery rate to have as a polymer film for an inner liner.

The content of the polyether-based segment in the base film may be 2% to 40% by weight, 3% to 35% by weight, or 4% to 30% by weight.

If the content of the polyether-based segment is less than 2% by weight of the entire base film, the modulus of the polymer film for the inner film or the inner liner may increase, thereby deteriorating the moldability of the tire or significantly deteriorating the physical properties due to repeated deformation. have. When the content of the polyether-based segment exceeds 40% by weight of the entire film, tire performance may be deteriorated due to poor gas barrier properties required for the tire inner liner. Since the reactivity to the adhesive is lowered, it may be difficult for the inner liner to easily adhere to the carcass layer, and the elasticity of the base film may increase, making it difficult to manufacture a uniform film.

The polyether-based segment may be combined with the polyamide-based segment or may exist in a dispersed state between the polyamide-based resins, which inhibits the growth of large crystals in the base film during tire manufacturing or automobile driving. Alternatively, it is possible to prevent the base film from being easily broken.

In addition, such a polyether-based segment can lower the modulus of the polymer film for the inner liner, so that even when a small force is applied during tire molding, the tire can be easily stretched or deformed according to the shape of the tire to facilitate the tire. Make it moldable. And, the polyether-based segment can suppress the rise of the rigidity of the film at low temperature and prevent crystallization at high temperature, and can prevent damage or tearing of the inner liner film due to repeated deformation, etc. By improving the resilience to deformation of the liner, it is possible to suppress the occurrence of wrinkles in the film due to permanent deformation, thereby improving the durability of the tire or inner liner.

The polyamide-based segment may allow the copolymer to have a mechanical property of a certain level or more, while preventing the modulus property from significantly increasing. In addition, as the polyamide-based segment is applied, the base film may have a thin thickness and have low air permeability, and ensure sufficient heat resistance and chemical stability.

The polyamide-based segment of the copolymer may include repeating units represented by the following Chemical Formula 1 or Chemical Formula 2.

[Formula 1]

In the above formula (1), R ₁ is a straight or branched alkylene group having 1 to 20 carbon atoms or a straight or branched arylalkylene group having 7 to 20 carbon atoms.

[Formula 2]

In Chemical Formula 2, R ₂ is a straight chain or branched alkylene group having 1 to 20 carbon atoms, and R ₃ is a straight chain or branched alkylene group having 1 to 20 carbon atoms or a straight chain or branched chain arylalkyl having 7 to 20 carbon atoms. It's Rengi.

In addition, the polyether-based segment of the copolymer may include repeating units represented by the following Chemical Formula 3.

[Formula 3]

In Chemical Formula 3, R ₅ is a straight or branched alkylene group having 1 to 10 carbon atoms, n is an integer from 1 to 100, R ₆ and R ₇ may be the same or different from each other, and each directly bond, -O- , -NH-, -COO- or -CONH-.

Further, in the base film, the polyamide-based resin and the above-described copolymer may be included in a weight ratio of 9:1 to 2:8, or 3:7: to 7:3. If the content of the polyamide-based resin is too small, the density or airtightness of the base film may deteriorate. In addition, if the content of the polyamide-based resin is too large, the modulus of the base film may be excessively high or the moldability of the tire may be deteriorated, and the polyamide-based resin crystallizes in a high-temperature environment that appears in the tire manufacturing process or the automobile driving process. It may be, and cracks may occur due to repeated deformation.

The base film may have a thickness of 30 to 300 μm, preferably 40 to 250 μm, and more preferably 40 to 200 μm. Accordingly, the polymer film for an inner liner of one embodiment of the present invention has a thinner thickness than the previously known, and has a low air permeability, for example, oxygen permeability of 200 cc/(m 2 ·24hr·atm) or less. have.

Since the previously known innerliner uses butyl rubber or a rubber-based copolymer, it is positioned relatively thick inside the carcass layer to secure a certain level of airtightness or higher. Accordingly, the previously known inner liner film has a weight of about 10% of the total weight of the tire, which has become an obstacle to improving the fuel efficiency of the automobile.

On the other hand, the polymer film for an inner liner of the above embodiment can realize an improved airtightness of 20% or more while having a weight of 30% or less compared to an inner liner using a copolymer of butyl rubber or a rubber component.

Meanwhile, the base film may further include a crosslinking agent. As the base film further contains a crosslinking agent, the crystallinity of the base film itself or the tendency to crystallize at a high temperature may be reduced. Specifically, according to the use of the crosslinking agent, a polymer that is used or synthesized in the manufacturing process of the base film, for example, a polyamide-based resin (a) and a polyamide-based segment and a polyether (poly-ether) ) Copolymer (b) comprising a segment or cross-linking reaction may occur between each other, and thus the crystallinity of the base film may be lowered.

The crosslinking agent may include a compound containing an oxazoline functional group. In particular, as the base film contains a compound containing an oxazoline functional group, the polymer film for the inner liner may have a low modulus characteristic with sufficient strength, and the base film may also be subjected to a high temperature molding process or stretching process of 100° C. or higher. The crystallinity of the is not so large, the modulus properties, elasticity or elastic recovery rate is not significantly reduced, such that excellent moldability can be secured.

Accordingly, the polymer film for the inner liner may have increased durability against external impact or self-deformation, and may prevent the film itself from being broken or torn during the storage process or the tire manufacturing process of the film. The orientation of the base film is lowered and the modulus is also optimized, thereby providing an inner liner film having high elasticity and durability. In addition, as the compound containing the oxazoline functional group is used, the physical and chemical properties of the base film may also be optimized for the innerliner film.

In addition, the base film may have a higher elasticity, including the polyamide-based resin and the compound containing the oxazoline functional group together with the above-described copolymer, and that the polymer chain is cut or the structure of the polymer is easily changed. By minimizing, it is possible to prevent an increase in the rigidity or crystallinity of the polymer film for the inner liner of the embodiment.

Due to the high elasticity of the base film, as the polymer structure is deformed or the polymer chain is cut in the process of elongating to a certain extent in a state where it is combined with the carcass rubber layer, the property or shape of the film is hardly changed. Therefore, there is little stress remaining on the base film after the elongation, so the stress measured in the contracted state after elongation may appear to be quite low. Accordingly, the polymer film for the inner liner of the embodiment including the base film can prevent a phenomenon in which stress is concentrated on a part in a tire manufacturing process or a vehicle driving process, and thus may have uniform physical properties as a whole and crack or fracture. Can be prevented.

The polyamide-based resin and the copolymer comprising the polyamide-based segment and the polyether-based segment may be bound through a compound containing the oxazoline-based functional group.

The compound containing the oxazoline functional group may include hydrogen, oxazoline substituted with one or more carbon atoms of 1 to 5 alkyl groups or 2 to 6 carbon atoms of an alkenyl group; (Meth)acrylate-based polymer in which one or more oxazolines are substituted; And it may include one or more selected from the group consisting of a styrene-based polymer substituted with one or more oxazolines.

The (meth)acrylate-based polymer or styrene-based polymer in which the oxazoline is substituted by one or more may have a weight average molecular weight of 1,000 to 300,000.

The base film may include 0.1% to 25% by weight of the compound containing the oxazoline functional group, or 1% to 20% by weight. If the content of the compound containing the oxazoline functional group is too small, the degree of crosslinking between the polymers contained in the base film is insufficient, so that crystallinity cannot be sufficiently lowered. If the content of the compound containing the oxazoline functional group is too high, the compatibility with other components included in the base film is lowered and the physical properties of the inner liner film are deteriorated, or crosslinking occurs unnecessarily in the base film, resulting in elasticity. It may degrade.

Meanwhile, the base film may further include a heat resistant agent. As the base film further contains a heat-resistant agent, the crystallinity of the polymer may be significantly lowered, so that even if it is left or exposed for a long time in a high-temperature environment, its physical properties are not significantly reduced. That is, as the heat-resistant agent is added to the base film, it is possible to significantly reduce the phenomenon that the base film is crystallized or hardened to a high level even during the molding process of the tire, and is also an inner part in the automobile driving process in which high temperature is generated by repeated deformation. It is possible to prevent the occurrence of cracks or breakage in the liner.

The base film may include 50 to 2,000 ppmw of heat resistance. If the content of the heat resistant agent is too small, the effect of improving the heat resistance may be negligible. In addition, if the content of the heat-resistant agent is too large, the physical properties of the base film may be deteriorated, and the effect of improving the heat-resistance according to the content of use may be substantially unnecessarily increasing the price of the final product.

As a specific example of such a heat resistant agent, an aromatic amine-based compound, a hindered phenol-based compound, a phosphorus-based compound, an inorganic compound, a polyamide-based compound, a polyether-based compound, or a mixture of two or more thereof can be used. The heat-resistant agent may be applied in the form of a powder or a liquid in a manufacturing method described later.

As a specific example of the hindered phenolic compound, N,N'-hexamethylenebis (3,5-ditertiary-4-hydroxy-hydrocinamide) or pentaerythritol tetrakis3-(3,5-di-t -Butyl-4-hydroxyphenyl)propionate (Pentaerythritol Tetrakis(3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate), Irganox 1010 as a commercial product), etc., but used as the heat-resistant agent Examples of possible hindered phenolic compounds are not limited thereto.

Specific examples of the aromatic amine-based compound, 2,2,4-trimethyl-1,2-dihydro quinoline or a polymer thereof, phenyl β-naphthyl amine, phenyl-α-naphthyl amine, aldol-α-naphthyl amine , N,N'-bis(1-methyl, heptyl)-p-phenylene diamine, N,N'-bis(1-ethyl-3-methylphenyl)-p-phenylene diamine, p-iso-propoxyl diamine Phenyl amine, 6-ethoxy-2,2,4-trimethyl 1,2-dihydro quinoline, N-phenyl-N'-isopropyl-para-phenylene diamine, di-beta-naphthyl-paraphenylene diamine , 4,4'-bis(α, α-dimethylbenzyl-diphenylamine), N'N'-nucleic acid-1,6-diyl bis(3-(3,5-di-tert-butyl)-4- Hydroxyphenyl-propionamide) or a mixture of two or more thereof, but examples of the aromatic amine-based compound usable as the heat resistant agent are not limited thereto.

Specific examples of the phosphorus-based compound, triphenyl phosphate (PPP), triaryl phosphate, aromatic phosphate ester, 2-ethylhexyl diphenyl phosphate, triethylene phosphate, tricresyl phosphate (TCP), cresyl phenyl phosphate, chlorethyl phosphate , Tris-β-chlorpropyl phosphate, trisdichlorpropyl phosphate, halogen-containing condensed phosphate esters, aromatic condensed phosphate esters, polyphosphates, red phosphorus, or mixtures of two or more thereof, but examples of phosphorus-based compounds that can be used as the heat resistant agent It is not limited to this.

Specific examples of the inorganic compound, iodide compounds such as Mg(OH) ₂ , Al(OH) ₂ , Sb ₂ O ₃ , guidine salt, Sb ₂ O ₅ , zinc borate, molybdenum compound, zinc stannate, CuI or KI, or And mixtures of two or more of these.

Even when a mixture of CuI and KI is used as the heat-resistant agent, the heat resistance of the base film can be greatly improved, and even when it is left or exposed for a long time in a high-temperature environment, the change in physical properties of the base film itself is not large.

When a mixture of CuI and KI is used as the heat-resistant agent, it can be used at 50ppmw to 1,000ppw compared to the paper film layer. And, the content of copper (Cu) in the mixture of CuI and KI may be 5 to 10% by weight.

Even when the mixture of CuI and KI is used, long-term heat resistance is greatly reduced without significantly affecting other physical properties of the base film by significantly reducing the content of the heat-resistant agent used (for example, 50ppmw to 1,000ppw in the base film) Can be improved.

Meanwhile, the base film may be an unstretched film. When the base film is in the form of an unstretched film, it has a low modulus and a high strain and can be suitably applied to a tire forming process in which high expansion occurs. In addition, since the crystallization phenomenon hardly occurs in the unstretched film, damage such as cracks can be prevented even by repeated deformation. In addition, since the unstretched film has little variation in orientation and physical properties in a specific direction, an inner liner having uniform physical properties can be obtained. As shown in the method of manufacturing a polymer film for an inner liner, which will be described later, a method of suppressing the orientation of the base film as much as possible, for example, viscosity adjustment through optimization of the melt extrusion temperature, changing the die specification, or adjusting the winding speed, etc. Through the method, the base film may be prepared as an unoriented or unstretched film.

When an unstretched film is applied as the base film, a polymer film for an inner liner can be easily manufactured in a cylindrical or sheet form in a tire manufacturing process. In particular, when the unstretched sheet-like film is applied to the base film, there is no need to separately build a film production facility for each tire size, and it is preferable because it is possible to minimize impact and wrinkles applied to the film during transport and storage. . In addition, in the case of manufacturing the base film in a sheet form, a process of adding an adhesive layer to be described later can be performed more easily, and damage or distortion caused during the manufacturing process due to a difference in specifications between the molding drum and the like can be prevented.

On the other hand, the polymer film for the inner liner of the embodiment may further include an adhesive layer formed on at least one surface of the base film and including a resorcinol-formalin-latex (RFL)-based adhesive.

The adhesive layer comprising the resorcinol-formalin-latex (RFL)-based adhesive has excellent adhesion and adhesion retention performance to the base film and the tire carcass layer, and accordingly heat generated in the tire manufacturing process or running process, etc. Or by preventing the breakage of the interface between the inner liner film and the carcass layer caused by repeated deformation, the polymer film for the inner liner can have sufficient fatigue resistance.

The main properties of the adhesive layer described above seem to be due to the inclusion of a specific resorcinol-formalin-latex (RFL) based adhesive with a specific composition. As the adhesive for the inner liner, a rubber-type tie gum or the like was used, and thus an additional vulcanization process was required. On the other hand, the adhesive layer includes a resorcinol-formalin-latex (RFL)-based adhesive of a specific composition, and not only has high reactivity and adhesion to the base film, but also compresses at high temperature heating conditions without increasing the thickness too much. The base film and the tire carcass layer may be firmly combined. Accordingly, it is possible to reduce the weight of the tire and improve the fuel efficiency of the tire, and to prevent a phenomenon in which the carcass layer, the inner liner layer, or the base film and the adhesive layer are separated even during repeated deformations in the tire manufacturing process or the vehicle driving process. Can be.

In addition, since the adhesive layer may exhibit high fatigue properties even for physical/chemical deformations that may be applied during the tire manufacturing process or the vehicle operation process, the adhesive layer may also be used during the manufacturing process under high temperature conditions or during the vehicle operation process subject to long-term mechanical deformation. It can minimize the deterioration of other physical properties.

In addition, the resorcinol-formalin-latex (RFL)-based adhesive is capable of cross-linking between latex and rubber, thereby exhibiting adhesive performance, and since it is a physically latex polymer, it has low curing and has flexible properties such as rubber. , Resorcinol-formalin is capable of chemical bonding between the methirol end group of the polymer and the base film. Accordingly, when the resorcinol-formalin-latex (RFL)-based adhesive is applied to the base film, sufficient adhesive performance can be realized.

The resorcinol-formalin-latex (RFL)-based adhesive is 2 to 32% by weight, preferably 10 to 20% by weight and preferably 68 to 98% by weight, preferably 80 to 80% by weight of a condensate of lesocinol and formaldehyde. 90% by weight.

The condensation product of lesocinol and formaldehyde may be obtained by mixing lesosinol and formaldehyde in a molar ratio of 1:0.3 to 1:3.0, and preferably 1:0.5 to 1:2.5, followed by condensation reaction. In addition, the condensate of lesocinol and formaldehyde may be included in an amount of 2% by weight or more based on the total amount of the entire adhesive layer in terms of chemical reaction for excellent adhesion, and may be included in an amount of 32% by weight or less to secure proper fatigue properties. have.

The latex may be one or a mixture of two or more selected from the group consisting of natural rubber latex, styrene/butadiene rubber latex, acrylonitrile/butadiene rubber latex, chloroprene rubber latex and styrene/butadiene/vinylpyridine rubber latex. The latex may be included in an amount of 68% by weight or more based on the total amount of the entire adhesive layer for flexibility of the material and effective crosslinking reaction with rubber, and in an amount of 98% by weight or less for chemical reaction with the base film and rigidity of the adhesive layer.

The adhesive layer may have a thickness of 0.1 to 20 μm, preferably 0.1 to 10 μm, more preferably 0.2 to 7 μm, even more preferably 0.3 to 5 μm, one surface of the polymer film for inner liner, or It can be formed on both surfaces.

If the thickness of the adhesive layer is too thin, the adhesive layer itself may become thinner when the tire is expanded, the crosslinking adhesive strength between the carcass layer and the base film may be lowered, and stress may be concentrated due to concentration of stress in a portion of the adhesive layer. In addition, if the adhesive layer is too thick, interfacial separation may occur in the adhesive layer, thereby deteriorating fatigue properties. In addition, it is common to form an adhesive layer on one surface of the base film in order to adhere the inner liner film to the carcass layer of the tire.However, when a multi-layered inner liner film is applied or the inner liner film wraps a bead, a tire forming method is used. And if it is necessary to adhere to the rubber on both sides according to the structural design, it is preferable to form an adhesive layer on both sides of the base film.

Meanwhile, according to another embodiment of the present invention, a pneumatic tire including the polymer film for the inner liner may be provided.

As described above, since the polymer film for the innerliner of the one embodiment can realize excellent airtightness even with a thin thickness, the pneumatic tire can be lighter than the previously known pneumatic tire to improve the fuel efficiency of the vehicle. . In addition, the film itself is crystallized or film during the tire manufacturing process in which the polymer film for the inner liner of the above-described embodiment exhibits low modulus and low crystallinity and a large deformation is performed under high temperature conditions or a vehicle driving process in which repeated deformation is continuously applied. It is possible to prevent the occurrence of damage such as cracks inside.

The pneumatic tire may have a structure of a commonly known pneumatic tire, except that the polymer film for a specific inner liner described above is included. For example, the pneumatic tire may include a tread portion; A pair of shoulder portions respectively continuous to both sides around the tread portion; A pair of side wall portions successive to each of the shoulder portions; A pair of bead portions successive to each of the side wall portions; A body fly portion formed inside the tread portion, the shoulder portion, the side wall portion and the bead portion; A belt portion and a cap fly portion sequentially stacked between the inner surface of the tread portion and the body fly portion; And it may include an inner liner film coupled to the inside of the body fly.

According to the present invention, even with a thin thickness, excellent airtightness and gas barrier properties (low oxygen permeability) can be realized to lighten the tire and improve the fuel efficiency of the vehicle, and have excellent mechanical properties such as high durability and fatigue resistance, along with excellent formability. A pneumatic tire comprising a polymer film for an inner liner having a small crack generation and a polymer film for the inner liner may be provided.

In addition, the polymer film for the inner liner provided above may have a low modulus property with sufficient strength, and the crystallinity of the base film is not so great even through a molding process or elongation process at a temperature of 100° C. or higher, so that the modulus property, elasticity or elasticity Since the recovery rate and the like are not significantly reduced, excellent moldability can be secured.

1 schematically shows the structure of a tire.

The invention is described in more detail in the following examples. However, the following examples are only illustrative of the present invention, and the contents of the present invention are not limited by the following examples.

[ Example : For inner liner Preparation of polymer film]

< Example 1 >

(1) Preparation of base film

Polyamide-based resin (nylon 6) having a relative viscosity (96% solution of sulfuric acid) 3.3 and copolymer resin having a weight average molecular weight of about 105,000 (20% by weight of a polyether-based segment having a polytetramethylene oxide at the terminal of the amine group as a main chain) Ethylene-propylene copolymer (density: 0.870 g/cm 3) grafted (0.7% by weight) with maleic anhydride (density: 0.870 g/cm 3) grafted with 80% by weight of polyamide-based segment of caprolactam was mixed in a weight ratio of 4:4.8:1.2 , By adding 0.0001 parts by weight of 1 part by weight of the oxazoline-based compound and heat-resisting agent (a mixture of copper iodide and potassium iodide-content of copper (Cu) in a mixture of 7% by weight) to 100 parts by weight of the mixture to prepare a base film preparation mixture .

Then, the mixture was extruded while maintaining a uniform flow of molten resin through a T-die (die gap [1.0 mm]-1.0 mm) at 260°C, and melted using an air knife on the surface of the cooling roll controlled at 25°C. The resin was cooled and solidified into a film of uniform thickness. Then, an unstretched base film having a thickness of 100 um below was obtained without going through a stretching and heat treatment section at a speed of 15 m/min.

(2) Application of adhesive

After mixing resorcinol and formaldehyde in a molar ratio of 1:2, condensation reaction was performed to obtain a condensate of lesocinol and formaldehyde. 12% by weight of the condensate of lesocinol and formaldehyde and 88% by weight of styrene/butadiene-1,3/vinylpyridine latex were mixed to obtain a resorcinol-formalin-latex (RFL) adhesive having a concentration of 20%.

Then, the resorcinol-formalin-latex (RFL)-based adhesive was coated on the base film to a thickness of 1 um using a gravure coater, dried and reacted at 150° C. for 1 minute to form an adhesive layer.

< Example 2 >

The same as in Example 1, except that the relative polyamide-based resin, the copolymer resin having a weight average molecular weight of about 105,000, and the ethylene-propylene copolymer grafted with maleic anhydride were mixed in a weight ratio of 4:4.2:1.8. A base film was prepared by a method, and an adhesive layer was formed on one surface of the base film in the same manner as in Example 1.

< Example 3 >

The same as in Example 1, except that a relative polyamide-based resin, a copolymer resin having a weight average molecular weight of about 105,000, and an ethylene-propylene copolymer grafted with maleic anhydride were mixed in a weight ratio of 4:5.4:0.6. A base film was prepared by a method, and an adhesive layer was formed on one surface of the base film in the same manner as in Example 1.

< Example 4 >

The same as in Example 1, except that a relative polyamide-based resin, a copolymer resin having a weight average molecular weight of about 105,000, and an ethylene-propylene copolymer grafted with maleic anhydride were mixed in a weight ratio of 4:3:3. A base film was prepared by a method, and an adhesive layer was formed on one surface of the base film in the same manner as in Example 1.

[ Comparative example : For inner liner Preparation of polymer film]

(1) Preparation of base film

85% by weight of a nylon 6 resin having a relative viscosity (96% solution of sulfuric acid) 3.3 and a copolymer resin having a weight average molecular weight of 45,000 [10% by weight of a polyether-based segment based on polytetramethylene oxide and 90% of a capamide of polyamide based on caprolactam] Synthesis using wt%] 15 wt% was mixed to obtain an unstretched base film (CE1) having a thickness of 100 um in the same manner as in Example 1.

(2) Application of adhesive

In the same manner as in Example 1, a resorcinol-formalin-latex (RFL)-based adhesive was coated on the base film CE1 to a thickness of 1 um using a gravure coater, dried and reacted at 150° C. for 1 minute to adhere the adhesive layer. Formed.

< Experimental Example : For inner liner Measurement of physical properties of polymer film>

Experimental Example 1 : Durability measurement experiment

(One) Pneumatic Tire manufacturing

Tires of the 205R/75R15 standard were manufactured and evaluated with the innerliner films of the above Examples and Comparative Examples. At this time, 1300De'/2ply HMLS tire cord was used as the cord included in the body ply, steel cord was used as the belt, and N66 840De'/2ply was applied as the cap ply.

Specifically, the prepared inner liner film was wrapped on a tire forming drum, and 3 cm length was superimposed to fix the inner liner film and the overlapping portion was fixed with a 1 mm thick tie gum. In addition, a 2 mm thick shoulder reinforced rubber sheet was attached to a portion of the inner liner corresponding to the position where the crimp was to be formed, 5 cm wide from 9 cm to 14 cm from the center of the drum.

In addition, a rubber for body ply is laminated on the inner liner film, and a bead wire; A belt part; Cap fly part; And a rubber layer for forming a tread portion, a shoulder portion, and a side wall portion sequentially to prepare a green tire.

The green tires thus manufactured were put into a mold, and tires were manufactured through vulcanization for 160 degrees and 30 minutes.

(2) Durability measurement experiment

The durability of the manufactured tire was experimentally evaluated using the American FMVSS139 tire durability measurement method. This durability measurement was carried out in two ways: Step Load Endurance Test to increase the load step by step and High Speed Test to increase the speed step by step.

The tire travels about 60 million cycles under actual use, and these 60 million cycles correspond to about 12 million cycles under the FMVSS139 standard. That is, it can be judged that tires capable of performing more than about 12 million cycles under the FMVSS139 Test show durability suitable for an actual use environment.

Results of Experimental Example 1 Example 1 Example 2 Example 3 Example 4 Comparative example Step Load Endurance Test About 14 million_ About 20 million About 15 million About 18 million About 12 million High Speed Endurance Test About 15 million About 21 million About 18 million About 19 million About 14 million

As shown in Table 1, it was confirmed that the tire to which the innerliner film of the example was applied has superior durability compared to the tire to which the polymer film for innerliner of the comparative example was applied.

As a result, the innerliner film of the embodiment may have lower modulus characteristics and higher elasticity or elastic recovery rate as the innerliner film of the embodiment has a relatively low crystallinity, so that the innerliner film can be used even in a vehicle driving process in which continuous deformation and external pressure are applied. It seems that this is due to securing a higher durability by preventing the phenomenon of breakage or tearing.

Experimental Example 2 : Tire manufacturing process

The tire innerliner films of the above Examples and Comparative Examples were applied to prepare 100 tires, respectively, and the inside of the manufactured tires was visually observed to measure the number of normal products without any film defects or internal defects such as cracks. The production yield of normal products was expressed by tire manufacturing processability.

At this time, the green tire or the tire after vulcanization was not crushed, and the standard deviation of the diameter was within 5%, which was evaluated as'good'. In addition, it was evaluated as'bad' when the tire was not manufactured properly or the inner liner inside the tire was melted or torn and damaged or the standard deviation of the diameter exceeded 5% due to crushing on the tire after vulcanization or green tire.

Results of Experimental Example 2 Example 1 Example 2 Example 3 Example 4 Comparative example Tire manufacturing process Good Good Good Good Bad

Experimental Example 3 : Air permeability

The oxygen permeability of the tire inner liner films obtained in the above Examples and Comparative Examples was measured. The specific measuring method is as follows.

(1) Oxygen permeability: Measured under an atmosphere of 25 degrees 60RH% using an Oxygen Permeation Analyzer (Model 8000, manufactured by Illinois Instruments) by the method of ASTM D 3895.

Experimental Example 4 : Durability measurement experiment

Modulus was measured at room temperature without stretching the polymer film for a tire inner liner obtained in Examples and Comparative Examples. Then, the modulus was measured by stretching 100% at room temperature based on the MD (Machine Direction) direction of the polymer film for the inner liner. The specific measuring method is as follows.

(1) Measuring equipment: Universal testing machine (Model 4204, Instron)

(2) Measurement conditions: 1) Head Speed 300mm/min, 2) Grip Distance 100mm, 3) Sample Width 10mm, 4) 25℃ and 60RH% atmosphere

(3) Each was measured 5 times, and the average value was obtained.

Experimental Example 5 : Measurement of air pressure maintenance performance

Tires were manufactured by applying the tire inner liner films of the above Examples and Comparative Examples to the 205R/65R16 standard. Then, the manufactured tire was compared and evaluated by measuring the air pressure retention rate (IPR Internal Pressure Retention) for 90 days according to the following general formula 2 under a pressure of 101.3 kPa at a temperature of 21° C. using the ASTM F1112-06 method.

[Formula 2]

Results of Experimental Examples 4 to 4 Load at 100% elongation at room temperature (kgf)
/
Load per unit thickness at 100% elongation at room temperature (gf/um) Oxygen permeability
cc/(㎡ㆍ24hrㆍatm) 90-day air pressure retention rate (%) Example 1 1.26/16.4 83 95.2 Example 2 1.12/14.2 95 93.4 Example 3 4.12/42 30.2 - Example 4 1.02/11.2 625 87

As shown in Table 3 above, in the embodiment, a base film layer having uniform physical properties may be formed in the entire film region, and the polymer film for tire innerliner of the embodiment using the base film layer has excellent moldability. In addition to having, it has high airtightness and air pressure retention performance.

Claims (17)

Polyamide resins;
A copolymer comprising a polyamide-based segment and a poly-ether-based segment; And
And a base film containing an olefinic polymer compound;
The olefin-based polymer compound includes at least one compound selected from the group consisting of an olefin-based polymer, an olefin-based copolymer and an olefin-based polymer or copolymer grafted with dicarboxylic acid or an acid anhydride thereof,
The base film contains 1 to 40% by weight of the olefin-based polymer compound,
The content weight ratio between the polyamide-based resin and the copolymer in the base film is 8:2 to 2:8,
The content of the polyether-based segment in the base film is 2% to 40% by weight,
Polymer film for inner liner.
delete According to claim 1,
The olefin polymer compound has a density of 0.820 g/cm 3 to 0.960 g/cm 3, a polymer film for an inner liner.
According to claim 1,
The olefin-based copolymer comprises at least one selected from the group consisting of ethylene-propylene copolymer and ethylene-styrene copolymer, polymer film for inner liner.
According to claim 1,
A polymer film for an inner liner having a content of grafted dicarboxylic acid or acid anhydride thereof in the olefin-based polymer or copolymer in which the dicarboxylic acid or acid anhydride thereof is grafted is 0.05% to 5% by weight.
According to claim 1,
The dicarboxylic acid is a group consisting of maleic acid, phthalic acid, itaconic acid, citraconic acid, alkenylsuccinic acid, cis-1,2,3,6 tetrahydrophthalic acid and 4-methyl-1,2,3,6 tetrahydrophthalic acid Polymer film for an inner liner, comprising at least one selected from.
delete According to claim 1,
The base film further includes a crosslinking agent, a polymer film for an inner liner.
The method of claim 8,
The crosslinking agent comprises a compound containing an oxazoline functional group, a polymer film for an inner liner.
According to claim 1,
The polymer film for an inner liner having a relative viscosity (96% solution of sulfuric acid) of the polyamide resin is 3.0 to 4.0.
According to claim 1,
A polymer film for an inner liner having a weight average molecular weight of 50,000 to 500,000 of the copolymer containing the polyamide-based segment and the polyether-based segment.
delete delete According to claim 1,
The base film further comprises a heat-resistant agent 50 to 2,000ppmw, a polymer film for an inner liner.
According to claim 1,
A polymer film for an inner liner formed on at least one surface of the base film and further comprising an adhesive layer comprising a resorcinol-formalin-latex (RFL)-based adhesive.
The method of claim 15,
The adhesive layer has a thickness of 0.1㎛ to 20㎛, polymer film for inner liner.
A pneumatic tire comprising the polymer film for the inner liner of claim 1.

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