KR101338506B1 - Film for tire inner-liner and preparation method thereof - Google Patents

Abstract

The present invention, polyamide-based resin or a precursor thereof; And a copolymer including 5 to 50 wt% of a polyether-based segment based on the total weight of the film, having a thickness of 30 to 300 μm, and a load generated at 100% elongation after heat treatment at 180 ° C. for 10 minutes at room temperature. A film for a tire innerliner, which is not more than twice the load generated at 100% elongation, and a polyamide-based resin or a precursor thereof; And forming a copolymer by polymerizing 5 to 50 wt% of a polyether resin based on the total weight of the film; And a method of manufacturing the film for tire innerliner comprising the step of melting and extruding the copolymer to form a film.

Description

FILM FOR TIRE INNER-LINER AND PREPARATION METHOD THEREOF}

The present invention relates to a film for a tire inner liner and a method of manufacturing the same, and more particularly, to realize excellent airtightness even at a thin thickness, to enable the reduction of tire weight and the improvement of automobile fuel efficiency, and excellent moldability in the tire manufacturing process. It relates to the film for tire innerliner shown, and its manufacturing method.

The tires support the load of the vehicle, alleviate the impact from the road surface, and transmit the driving or braking force of the vehicle to the ground. In general, a tire is a composite of fiber / steel / rubber and generally has a structure as shown in FIG. 1.

Tread (1): It is a part that comes into contact with the road surface, it should provide friction force necessary for braking and driving, good abrasion resistance, able to withstand external impact, and low heat generation.

Body Ply (or Carcass) (6): A layer of cord inside the tire, which must support loads, withstand impacts, and be resistant to fatigue during rolling.

Belt (5): Located between the body plies, consisting of steel wires in most cases to mitigate external shocks and maintain a wide tread ground to provide excellent driving stability.

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

Inner Liner (7): Located on the inside of the tire instead of the tube, it prevents air leakage to enable pneumatic tires.

BEAD (9): A square or hexagonal wire bundle with rubber coating on the wire that rests and secures the tire to the rim.

CAP PLY (4): A special cord paper placed on the belt of some passenger radial tires that minimizes belt movement when driving.

APEX (8): A triangular rubber filler used to minimize the dispersion of beads, to mitigate external impacts, to protect the beads, and to prevent the ingress of air during molding.

Recently, tube-less tires in which high pressure air of about 30 to 40 psi is injected without the use of a tube are commonly used. To this end, a highly airtight inner liner is disposed in the carcass inner layer.

Previously, a tire inner liner having rubber components such as butyl rubber or halobutyl rubber, which is relatively low in air permeability, was used. In this inner liner, the rubber content or the thickness of the inner liner had to be increased in order to obtain sufficient airtightness . As a result, the total weight of the tire is increased, fuel consumption of the vehicle is lowered, air pockets are formed between the inner rubber of the carcass layer and the inner liner, or the shape and physical properties of the inner liner are changed appear.

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

However, any previously known method has had a limit in maintaining excellent air permeability and tire formability while sufficiently reducing the thickness and weight of the innerliner. In addition, the inner liner obtained by the previously known method has often failed to have sufficient fatigue resistance such as cracking due to repeated deformation in the manufacturing process or the running process of the tire.

Accordingly, there is a demand for development of a thinner inner liner capable of realizing properties such as excellent airtightness or formability while having a thinner thickness and making a tire lighter.

The present invention is to provide a film for a tire innerliner to realize excellent airtightness even at a thin thickness to enable the weight reduction of the tire and the improvement of automobile fuel economy, and excellent moldability in the tire manufacturing process.

The present invention also provides a method for producing the film for a tire innerliner.

The present invention is polyamide-based segment; And a copolymer including 5 to 50 wt% of a polyether-based segment based on the total weight of the film, having a thickness of 30 to 300 μm, and a load generated at 100% elongation after heat treatment at 180 ° C. for 10 minutes at room temperature. It provides a film for tire innerliner that is less than twice the load generated at 100% elongation.

In addition, the present invention is a polyamide-based resin or a precursor thereof; And forming a copolymer by polymerizing 5 to 50 wt% of a polyether resin based on the total weight of the film; And it provides a method for producing a film for the tire innerliner comprising the step of melting and extruding the copolymer to form a film.

BEST MODE FOR CARRYING OUT THE INVENTION A film for a tire inner liner according to a specific embodiment of the present invention and a method for producing the same will be described in detail.

According to one embodiment of the invention, the polyamide-based segment; And a copolymer including 5 to 50 wt% of a polyether-based segment based on the total weight of the film, having a thickness of 30 to 300 μm, and a load generated at 100% elongation after heat treatment at 180 ° C. for 10 minutes at room temperature. A film for tire innerliner that is not more than twice the load that occurs at 100% elongation can be provided.

The inventors of the present invention can realize the excellent airtightness and high air pressure retention performance even with a thin thickness of the film for tire innerliner produced by copolymerizing the polyamide-based segment and the polyether-based segment in a specific content. In the experiment, it was confirmed that the tire can be easily stretched or deformed even when a small force is applied, so that excellent molding characteristics can be exhibited and constant physical properties can be maintained even after the heat treatment step.

In addition, since the tire innerliner film does not require a large amount of additional additives or rubber components to improve physical properties, the manufacturing process can be simplified and the pneumatic holding performance can be realized even at a thin thickness. Accordingly, by using the tire innerliner film of the embodiment of the present invention, it is possible to reduce the weight of the tire to improve the fuel efficiency of the vehicle, and maintain the proper air pressure even after long-term use to reduce the overturn accident and fuel economy caused by low air pressure. It is possible to prevent it and to produce a tire having excellent performance even with a simple manufacturing process.

The tire innerliner film including the copolymer of the polyamide-based segment and the polyether-based segment may include only the copolymer as a substrate of the film. Accordingly, the film for inner liner can be distinguished from a film for a prior tire inner liner having a rubber component or a thermoplastic resin as a main component of the substrate, and does not require an additional vulcanizer . The term " substrate of the film " refers to a substrate of a resin or a rubber component that retains the shape of the film except for an additional dispersion component such as an additive in the film for a tire innerliner. The base material often contains various rubber components or resin components. However, the film for a tire innerliner according to an embodiment of the present invention may include a polyamide resin or the like together with the copolymer as the base material, but may include only the copolymer, and in this case, As shown in FIG.

The characteristics of the film for tire innerliner may be due to copolymerization of a polyether-based segment that provides elastomeric properties to the polyamide-based segment in a specific content range. That is, the polyamide-based segment exhibits excellent airtightness due to its inherent molecular chain properties, for example, about 10 to 20 times higher than that of butyl rubber generally used in tires at the same thickness, and is not so high compared to other resins. Not modulus properties. In addition, since the polyether-based segment is used at 5 to 50% by weight based on the total weight of the film and copolymerized together with the polyamide-based segment, the film for the tire inner liner has a relatively small load generated according to a specific elongation. It may have a low modulus or a low modulus, and may not have a significant change in physical properties of the film even after a specific heat treatment process.

Accordingly, the inner liner film may be stretched or deformed to conform to the shape of the tire even when a very small force is applied when forming the tire, and may prevent a sudden increase in load generated due to rigidity or stretching even after the heat treatment process. Can be. Accordingly, by using the inner liner film, the tire can be easily molded and processed, and the shape or quality of the green tire or the final tire to be molded can be improved.

Specifically, the inner liner film may have a load generated at 100% elongation (100%) after heat treatment at 180 ° C. for 10 minutes at less than twice the load generated at 100% elongation at room temperature. In the inner liner film, if the load generated at 100% elongation after heat treatment at 180 ° C. for 10 minutes exceeds 2 times the load generated at 100% elongation at room temperature, the inner liner is not sufficiently stretched even if an expansion pressure is applied. As a result, the shape of the green tire to be molded may be deteriorated, and the rigidity may increase rapidly after the heat treatment process, and thus the final tire molding may be difficult. The load generated in the film for the tire inner liner during the stretching may be measured as the Max load value in the 100% elongation section based on the MD (Machine Direction) direction of the film.

In addition, the load generated when 100% elongation after heat treatment of the tire inner liner at 180 ° C. for 10 minutes may be 6 kgf or less. That is, the tire inner liner maintains proper mechanical properties and elasticity even after heat treatment during tire molding, so that the tire inner liner can be easily elongated or deformed even when a small force is applied, and exhibits stable physical properties in the tire even after tire molding. It can have stable physical properties against external forces such as severe tensile and compressive deformation that may occur during the driving process of the car, thereby improving the durability of the tire.

In addition, polyamide-based resins are generally known to be easily crystallized by heat, but the film for tire innerliner includes the polyether-based segment in a specific content so that crystals grow according to heat or external deformation in the film. It can be suppressed. Accordingly, the inner liner film is not easily crystallized by the heat generated in the tire, and the modulus or rigidity is not greatly changed even by long-term operation, and cracks that may occur during operation can be minimized.

And, as shown in the method for manufacturing the tire inner liner film described below, the tire inner liner film is applied to a method of suppressing the orientation as much as possible, for example, viscosity adjustment through optimization of the melt extrusion temperature, the mold die specification Since it is made of an unoriented or unoriented film by changing or adjusting the winding speed, it can have excellent mechanical properties and moldability even if the content of the polyether-based segment in the film is not so high.

On the other hand, the tire innerliner film may have a thickness of 30 to 300 ㎛, preferably 40 to 250 ㎛, more preferably 40 to 200 ㎛. The tire inner liner film may have a thin thickness as compared to the previously known inner liner film and may have a low air permeability, for example, an oxygen permeability of 200 cc / (m 2 · 24 hr · atm) or less.

The polyamide-based segment means a repeating unit containing an amide group (-CONH-), and may be formed from a polyamide-based resin participating in the polymerization reaction or a precursor thereof.

Since the polyamide-based segment has sufficient heat resistance and chemical stability, it is possible to prevent the innerliner film from being deformed or modified when exposed to high temperature conditions or chemicals such as additives applied during tire manufacturing. In addition, the polyamide-based segment may have a relatively high reactivity with respect to an adhesive (for example, resorcinol-formalin-latex (RFL) -based adhesive) as the polyamide segment is copolymerized with the polyether segment. The adhesive film can be easily adhered to the carcass part.

Specifically, the polyamide segment may be 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, nylon 66 / PPS copolymer, 6-nylon methoxymethylate, 6-610-nylon methoxymethylate and 612- And the main repeating unit contained in one type of polyamide resin selected from the group consisting of methacrylic acid, For example, the main repeating unit of nylon 6 is known in the formula (1) R ₁ is alkylene having 6 carbon atoms, the main repeating unit of other polyamide-based resin is also known to those skilled in the art.

In addition, the polyamide-based segment may include a repeating unit of Formula 1 or Formula 2.

[Chemical Formula 1]

In Formula 1, R ₁ may be a linear or branched alkylene group having 1 to 20 carbon atoms or a linear or branched alkylene group having 7 to 20 carbon atoms.

(2)

R ₂ is a linear or branched alkylene group having 1 to 20 carbon atoms and R ₃ is a linear or branched alkylene group having 1 to 20 carbon atoms or a linear or branched alkylaryl group having 7 to 20 carbon atoms It can be a ring.

As used herein, an "alkylene group" means a divalent functional group derived from an alkyl group, and an "arylalkylene group" means a 2 derived from an alkyl group to which an aryl group is introduced. Means a functional group.

Meanwhile, the polyether segment refers to a repeating unit including an alkyl oxide ('-Akyl-O-' group), and may be formed from a polyether resin or a precursor thereof that participates in a polymerization reaction.

The polyether-based segment can suppress the growth of large crystals in the tire innerliner film or prevent the film from being easily broken during the tire manufacturing process or the vehicle driving process. In addition, the polyether-based segment can lower the load generated during the modulus or stretching of the tire inner liner film, and thus can be stretched or deformed to conform to the shape of the tire even when a very small force is applied during tire forming. So that the tire can be easily molded. In addition, the polyether-based segment can suppress the increase in the rigidity of the film at low temperatures and prevent crystallization at high temperatures, and can prevent damage or tearing of the inner liner film due to repeated deformation, etc. By improving the resilience to the deformation of the liner to suppress the occurrence of wrinkles of the film due to permanent deformation it can improve the durability of the tire or innerliner.

The polyether segment may be a main repeating unit that may be included in a polyalkylene glycol resin or a derivative thereof. In this case, the polyalkylene glycol derivative may have an amine group, a carboxyl group, an isocyanate group, and the like of the polyalkylene glycol resin. It may be a derivative substituted with, preferably substituted with an amine group. Preferably, the polyether segment is one selected from the group consisting of polyethylene glycol, polypropylene glycol, polytetramethylene glycol, polyoxyethylene diamine, polyoxypropylene diamine, polyoxytetramethylene diamine, and copolymers thereof. It may be a main repeating unit included in the polyether resin.

Specifically, the polyether-based segment may include a repeating unit represented by the following formula (5).

[Chemical Formula 5]

In Formula _5, R 5 may be an alkylene group of a straight-chain or branched-chain having 1 to 10, n can be an integer from 1 to 100. In addition, R ₆ and R ₇ may be the same as or different from each other, and may be a direct bond, -O-, -NH-, -COO- or -CONH-, and preferably -NH-.

As shown in the production method described below, the copolymer of the polyamide-based segment and the polyether-based segment may be obtained by polymerizing a polyamide-based resin or a precursor thereof and a polyether-based resin. At this time, the weight average molecular weight of the polyether resin used may be 500 to 10,000, preferably 1,000 to 3,000. When the weight average molecular weight is less than 500, the polyether resin may not adequately suppress the growth of large crystals in the film for a tire inner liner or lower the modulus. In addition, when the weight average molecular weight is more than 10,000, the airtightness of the inner liner may be deteriorated. Such weight average molecular weight can be measured through conventionally well-known apparatus and methods, for example, GC-MS or GPC (Gel Permeation Chromatography).

The polyether segment may be included in 5 to 50% by weight, preferably 10 to 30% by weight based on the total weight of the film. Accordingly, the tire innerliner film may include a component other than the polyether segment, for example, polyamide based component, other components or additives in an amount of 50 to 95% by weight.

When the polyether-based segment is included at less than 5% by weight based on the total weight of the film, the load generated during modulus or stretching of the tire innerliner film is greatly increased, resulting in deterioration of the formability of the tire or repeated deformation. This can lead to a significant decrease in physical properties. In addition, when the polyether-based segment is included in excess of 50% by weight based on the total weight of the film, the airtightness of the film for the tire innerliner may be lowered, and the reactivity to the adhesive is lowered so that the innerliner is carcass. It may be difficult to easily adhere to the layer, and the elasticity of the innerliner may be greatly increased so that it may not be easy to prepare a uniform film.

If the content of the polyamide-based segment is too small, the density or airtightness of the tire inner liner film may be lowered. If the polyamide segment is too large, the modulus of the tire inner liner film may be too high or the moldability of the tire may be reduced. In addition, the innerliner may be crystallized in a high temperature environment during the tire manufacturing process or the automobile driving process, and cracks may occur in the innerliner film by repeated deformation.

On the other hand, the tire inner layer film may be an unstretched film. When the film for tire inner liner is an unstretched film, it has a low modulus and a high strain rate and can be suitably applied to a tire forming process in which high expansion occurs. In addition, crystallization phenomenon hardly occurs in the unstretched film, and damage such as cracks can be prevented even by repeated deformation. In addition, since the unstretched film does not have large variation in orientation and physical properties in a specific direction, an inner liner having uniform physical properties can be obtained. When the film for the tire inner liner is an unstretched film, it can be applied to both the cylindrical or sheet-like in the tire manufacturing process. However, when the tire inner liner film is a sheet type, it is not necessary to separately build a film manufacturing facility for each tire size, and the impact and wrinkles applied to the film during the transport and storage process may be minimized. In addition, when manufacturing the inner liner film in a sheet form, it is possible to easily add an adhesive, it is possible to prevent damage or dents, etc. occurring during the manufacturing process due to the difference in the molding drum and specifications.

In addition, as shown in Figure 1, the tire inner liner film can implement excellent airtightness even at a lower thickness than the previous inner liner film. Specifically, the inner liner film may realize high airtightness even at the same thickness as the inner liner of halobutyl rubber, which is generally used, and may exhibit superior airtightness as compared to natural wool. In addition, although the general nylon 6 stretched film may exhibit high airtightness, physical properties may be degraded or deformed during tire manufacturing or automatic driving, whereas the film for tire innerliner has excellent airtightness but changes in physical properties or shape. It is insignificant and the moldability of a tire can be improved. In Figure 1, the horizontal axis is the thickness of the log scale film, the vertical axis is the oxygen permeability (OTR), NR is a natural ball, Nylon film is a general nylon 6 stretched film, Innerliner Rubber # 1 and # 2 is a tire inner using halobutyl rubber Liner, Innerliner Film means a film for tire innerliner of an example of the invention.

On the other hand, since the tire innerliner film includes a copolymer of a polyamide-based segment and a polyether-based segment, it may exhibit improved adhesion, so that an additional adhesive layer or rubber layer may be laminated for firm adhesion with the carcass layer. no need. Accordingly, the film for tire innerliner may be adhered to the inner surface of the carcass using a conventional adhesive known to be used in a tire manufacturing process, for resorcinol-formalin-latex (RFL) for more uniform and stable adhesion. It is preferable to use a system adhesive.

Accordingly, the tire innerliner film may further include an adhesive layer formed on at least one surface, and the adhesive layer may include the resorcinol-formalin-latex (RFL) adhesive. Such an adhesive layer can be formed by a conventional adhesive layer constitution or manufacturing method including a resorcinol-formalin-latex (RFL) adhesive, and a film for a tire innerliner including such an adhesive layer is also a It is needless to say that the properties according to the examples can be satisfied, for example, the property that the low air permeability and the load generated at the time of constant elongation are maintained at a low level. In addition, the adhesive layer may have a thickness of 20 μm or less, preferably 0.1 to 10 μm, and may be formed on one or both surfaces of the tire innerliner film.

On the other hand, the tire inner liner film may further include a polyamide-based resin in order to improve mechanical properties or airtightness. Such a polyamide-based resin may be present on the film in a mixed state or in a copolymerized state with the copolymer of the polyamide-based segment and the polyether-based segment described above. As shown in the manufacturing method described later, the polyamide based resin may be mixed with a copolymer of a polyamide-based segment and a polyether-based segment, and then may be contained in the film for a tire inner liner by being melted and extruded.

The polyamide-based resin that may be further included may be used to improve the mechanical properties of the film for the tire inner liner, for example, heat resistance or chemical stability, and airtightness, but the tire inner liner manufactured when the amount used is too large The characteristic of the film for resin can be reduced. In particular, even when the polyamide-based resin is additionally used, the content of the polyether-based segment in the film should be maintained at 5 to 50% by weight. Accordingly, the polyamide-based resin and the polyamide-based segment And the sum of the amounts of other additives and the like should be 50 to 95% by weight.

The additionally available polyamide-based resin is not particularly limited, and in order to increase the compatibility with the copolymer, it is preferable to use a polyamide-based resin including the same or similar repeating units as the polyamide-based segment. .

In addition, such polyamide-based resins may have a relative viscosity of 2.5 to 4.0. If the relative viscosity is less than 2.5, a sufficient elongation can not be secured due to a decrease in toughness, so that it may occur during tire production or automobile operation. When the relative viscosity is more than 4.0, the modulus or viscosity becomes unnecessarily high, And the like. As the viscosity of such polyamide-based resin, a solvent and a method commonly used with a previously known viscometer such as a microtubular viscometer or a vibratory viscometer can be used without great limitation. For example, polyamide-based resin can be dissolved in 96% sulfuric acid, and the relative viscosity can be measured from the ratio of the falling rate of sulfuric acid and the polyamide resin solution.

Examples of the polyamide based resin include polyamide based resins such as copolymers of nylon 6, nylon 66, nylon 46, nylon 11, nylon 12, nylon 610, nylon 612, nylon 6/66, nylon 6/66 / 610 copolymers, nylon MXD6, nylon 6T, nylon 6 / 6T copolymers, nylon 66 / PP copolymers and nylon 66 / PPS copolymers; Or their N-alkoxyalkylates, for example methoxymethylate of 6-nylon, methoxymethylate of 6-610-nylon or methoxymethylate of 612-nylon, nylon 6, nylon 66, nylon Preference is given to using 46, nylon 11, nylon 12, nylon 610 or nylon 612.

Meanwhile, the tire inner liner film may further include additives of a heat resistant antioxidant, a heat stabilizer, an adhesion promoter, or a mixture thereof. Specific examples of the heat resistant antioxidants include N, N'-Hexamethylene-bis- (3,5-di-tert-butyl-4-hydroxy-hydrocinnamamide) (for example, commercially available products such as Irganox 1098), tetrakis [ methylene (3,5-di-t-butyl-4-hydroxyhydrocinnamate)] methane (for example, commercially available products such as Irganox 1010) or 4,4'-di-cumyl-di-phenyl-amine (for example, Naugard 445). Specific examples of the thermal stabilizer include bezoic acid, triacetonediamine, or N, N'-Bis (2,2,6,6-tetramethyl-4-piperidyl) -1,3-benzenedicarboxamide. However, the additives are not limited to the above examples, and those known to be usable for the film for the tire inner liner may be used without any particular limitation.

Meanwhile, according to another embodiment of the present invention, a polyamide-based resin or a precursor thereof; And forming a copolymer by polymerizing 5 to 50 wt% of a polyether resin based on the total weight of the film; And melting and extruding the copolymer to form a film. A method of manufacturing the film for tire innerliner may be provided.

The present inventors melt-extruded a polyamide-based resin or a copolymer obtained by polymerizing a precursor thereof and a polyether-based resin in a specific content to produce a film for a tire inner liner. Not only can achieve excellent airtightness and high pneumatic pressure retention, but also it can be easily elongated or deformed even when a very small force is applied during tire molding, so that excellent molding characteristics can be exhibited and constant physical properties can be maintained even after the heat treatment step. It was confirmed through the experiment to complete the invention.

As described above, the film for tire innerliner provided by the manufacturing method is a load generated at 100% elongation after 100% elongation after heat treatment at 180 ° C. for 10 minutes. It can be up to twice the load.

The polyamide-based resin or a precursor thereof; And polymerizing 5 to 50% by weight of the polyether resin based on the weight of the film may be performed under acidic conditions and nitrogen atmosphere. In addition, the polymerization reaction may include heating or melting at a temperature of 50 ° C. or more, and may include increasing or reducing the pressure depending on the reaction step. In the polymerization reaction, a method and apparatus commonly known to be used for the synthesis of a polyamide-based resin may be used without particular limitation.

The polyamide-based resin or a precursor thereof may be appropriately selected depending on the specific type of the polyamide-based segment included in the copolymer. For example, when the polyamide-based segment has a repeating unit of nylon 6, ε-caprolactam and adipic acid may be used as precursors of the polyamide-based resin.

Specifically, the polyamide-based resin is nylon 6, nylon 66, nylon 46, nylon 11, nylon 12, nylon 610, nylon 612, nylon 6/66 copolymers, nylon 6/66/610 copolymer, nylon MXD6 , Nylon 6T, nylon 6 / 6T copolymer, nylon 66 / PP copolymer, nylon 66 / PPS copolymer, methoxymethylated 6-nylon, methoxymethylated 6-610-nylon and 612-nylon methoxy One or more polyamide-based resins selected from the group consisting of methoxymethylates can be used. In addition, as the precursor of the polyamide-based resin, one of the aforementioned polyamide-based resin may be used.

As a polyether resin used for the said manufacturing method, Polyalkylene glycol resin; Or a derivative in which the terminal of the polyalkylene glycol resin is substituted with an amine group, a hydroxyl group, a carboxyl group, an isocyanate group, or the like. Preferably, the polyether resin may be polyethylene glycol, polypropylene glycol, polytetramethylene glycol, polyoxyethylene diamine, polyoxypropylene diamine, polyoxytetramethylene diamine, or a copolymer thereof.

Specifically, the polyether resin may include a compound of Formula 6 below.

[Chemical Formula 6]

In Formula 6, R ₁₅ is an alkylene group having 1 to 10 carbon atoms, n may be an integer of 1 to 100. In addition, R ₁₆ and R ₁₇ may be the same as or different from each other, and each of hydrogen, a hydroxy group, an amine group, a carboxyl group or an isocyanate group, preferably an amine group.

Details of the copolymer obtained by the method for manufacturing the tire innerliner film, that is, the content of the polyamide-based segment, the polyether-based segment and the content thereof, the specific physical properties or the additional components, etc. of the copolymer are as described above. .

The tire inner liner film obtained by the manufacturing method may have a load generated at 100% elongation after heat treatment at 180 ° C. for 10 minutes at 6 kgf or less, and has an oxygen permeability of 200 cc / (m 2 · 24hr · atm) or less. Can be.

On the other hand, the temperature of melting the copolymer may be 230 to 300 ℃, preferably 240 to 280 ℃. The melting temperature should be higher than the melting point of the polyamide-based resin, but if too high, carbonization or decomposition may occur, which may impair the physical properties of the film. It may be disadvantageous for producing a film.

On the other hand, the tire inner liner film may be an unstretched film having a thickness of 30 to 200 ㎛. The thickness of the extrudate can be adjusted according to the specifications of the apparatus such as the extruder used. In order to form an unstretched film, a method of adjusting the melt viscosity of the melt by adjusting the melt extrusion temperature, adjusting the discharge amount of the melt, changing the specification of the die, or controlling the winding speed of the film have. For example, the Lip Opening of the retaining die can be set to around 1 mm, and the too narrowing of the Lip Opening may be undesirable because the pressure applied to the die shear may be too high. In addition, it is desirable that the winding speed of the film is maintained at a proper speed in order to prevent problems of poor cooling and increase in orientation. For example, it is preferable to set the speed at 100 m / min or less, preferably 50 m / min or less Can be applied.

In addition, the method for producing a film for tire innerliner may further include forming an adhesive layer on at least one surface of the film after forming the film step through the melt extrusion. The forming of the adhesive layer may be performed by coating a resorcinol-formalin-latex (RFL) -based adhesive on one or both surfaces of the film according to a conventional manufacturing method, followed by drying. This adhesive layer may have a thickness of 20 μm or less, preferably 0.1 to 10 μm, and may be formed on one or both surfaces of the film for tire innerliner.

The coating or coating method or apparatus commonly used for the application may be used without any limitation, but may be a knife coating method, a bar coating method, a gravure coating method or a spray method, or a dipping method. have. However, it is preferable to use a knife coating method, a gravure coating method, or a bar coating method in terms of uniform application and coating of the adhesive.

After the adhesive layer is formed on one surface or both surfaces of the base film layer, the drying and the adhesive reaction may be carried out at the same time. However, considering the reactivity of the adhesive, it may be divided into a drying step and a heat treatment reaction step , The adhesive layer formation, the drying and the reaction step may be applied several times in order to apply the thickness of the adhesive layer or the multi-stage adhesive. In addition, after the adhesive is applied to the base film layer, the heat treatment may be performed by solidifying and reacting at 100 to 150 ° C. under heat treatment conditions for about 30 seconds to 3 minutes.

As described above, the tire inner liner film may further include a polyamide-based resin in order to improve mechanical properties or airtightness. Specific details of the polyamide-based resin that may be further included as described above.

Accordingly, the method for manufacturing the tire innerliner film may include a polyamide resin or a precursor thereof; And it may further comprise the step of melting and extruding at 230 to 300 ℃ by mixing a copolymer obtained by polymerizing 5 to 50% by weight of polyether resin with respect to the film weight and polyamide-based resin. Details of the melting and extruding step are the same as described above, and the process steps subsequent to the melting and extrusion are also the same as described above.

Meanwhile, in the forming of the copolymer or melting and extruding the copolymer, additives such as a heat resistant antioxidant or a heat stabilizer may be further added. Details of the additives are as described above.

According to the present invention, it is possible to provide a film for a tire innerliner and a method of manufacturing the same, which can realize excellent airtightness even at a thin thickness, thereby making it possible to reduce the weight of a tire and improve automobile fuel economy, and show excellent moldability in a tire manufacturing process. .

1 schematically shows the structure of a tire.
2 schematically shows the air permeability according to the material and thickness of the inner liner.

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

< Example  And Comparative Example : tire For inner liner  Manufacturing of Film>

Example 1

To a mixture of 70 wt% of ε-caprolactam and 30 wt% of polyoxyethylene diamine (Mw.1000) for resin polymerization for the inner liner film, adipic acid having the same mole number as the polyoxyethylene diamine was mixed, and the nitrogen atmosphere was 100 ° C. Melt for 30 minutes under The melt was heated at 250 ° C. for 3 hours and elevated to 8 kg / cm 2 to maintain pressure. Then, the pressure was reduced to 1 kg / cm 2 for 1 hour.

After manufacturing the reduced melt in the shape of a chip, the resulting chip is extruded into an annular die at a temperature of 260 ° C. for an unstretched tire inner liner having a thickness of 100 μm without passing through a stretching and heat treatment section at a speed of 30 m / min. Got.

The resorcinol-formalin-latex (RFL) -based adhesive was coated on the innerliner film to a thickness of 15 μm using a gravure coater, dried and reacted at 150 ° C. for 1 minute to form an adhesive layer.

The thickness of the manufactured tire innerliner film was measured using a gauge tester. At this time, the thickness of the film means a thickness of only the film excluding the adhesive layer.

Example 2

A 100 탆 unstretched tire innerliner film was obtained in the same manner as in Example 1, except that 60 wt% of epsilon caprolactam and 40 wt% of polyoxyethylene diamine were mixed.

Example 3

A 100 µm unstretched tire innerliner film was obtained in the same manner as in Example 1 except that 80 wt% of epsilon caprolactam and 20 wt% of polyoxyethylene diamine were mixed.

Example 4

A tire inner liner film having a thickness of 100 µm was obtained in the same manner as in Example 1, except that 90 wt% of epsilon caprolactam and 10 wt% of polyoxyethylene diamine were mixed.

Example 5

A tire inner liner film was obtained in the same manner as in Example 1 except that the thickness of the film was 50 μm.

Comparative Example 1

A 100 탆 unstretched tire innerliner film was obtained in the same manner as in Example 1 except that 97 wt% of epsilon caprolactam and 3 wt% of polyoxyethylene diamine were mixed.

Comparative Example 2

A 100 µm unoriented tire inner liner film was obtained in the same manner as in Example 1, except that 30 wt% of epsilon caprolactam and 70 wt% of polyoxyethylene diamine were mixed.

Comparative Example 3

A 100 탆 unstretched tire innerliner film was obtained in the same manner as in Example 1 except that only nylon 6 resin having a relative viscosity of 3.4 was used.

< Experimental Example >

Experimental Example 1 . Oxygen permeability experiment

Oxygen permeability of the tire innerliner film obtained in the above Examples and Comparative Examples was measured by the following method.

(1) Measuring method and condition

By the method of ASTM D 3895, using an Oxygen Permeation Analyzer (Model 8000, manufactured by Illinois Instruments) was measured in a 25 degree 60RH% atmosphere.

Experimental Example 2 . Measurement of load that occurs during stretching

1. Measurement of the load generated at 100% elongation at room temperature

The maximum load (Load At Specific Elongation) generated by stretching the film for tire innerliner obtained in the above Examples and Comparative Examples in the direction of MD (Machine Direction) at room temperature at 100% was measured. The specific measurement method is as follows.

(1) Measuring instrument: Universal Testing Machine (Model 4204, Instron)

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

(3) It measured five times and calculated | required the average value.

2. Measurement of the load generated at 100% elongation after heat treatment at 180 ℃ for 10 minutes

The tire inner liner films of Examples and Comparative Examples were heat-treated at 180 ° C. for 10 minutes using a hot air oven and cooled at room temperature. In addition, the maximum load (Load At Specific Elongation) generated by stretching 100% in the direction of MD (Machine Direction) at room temperature was measured. The specific measuring method was the same as the above '1.'

The measurement results of Experimental Examples 1 to 2 are shown in Table 1 below.

Experimental Example 1 to  2, measurement results Air permeability
[cc / ㎡ * 24hr * atm] Inner Liner Thickness [㎛] Generated load at 100% elongation at room temperature (A)
[kgf] 180 ° C., 10 minutes
Load generated at 100% elongation after heat treatment (B) [kgf] Value of B / A Example 1 108 100 1.88 3.22 1.713 Example 2 142 100 1.84 2.85 1.549 Example 3 90 100 2.28 4.11 1.803 Example 4 85 100 2.45 4.85 1.980 Example 5 141 50 1.62 2.55 1.574 Comparative Example 1 57 100 3.80 7.85 2.066 Comparative Example 2 450 100 1.38 2.25 1.630 Comparative Example 3 35 100 3.60 9.08 2.522

As shown in Table 1, it was confirmed that the tire innerliner of the embodiment exhibits air permeability of 200 cc / (m 2 · 24hr · atm) or less even at a thickness of 150 μm or less, thereby achieving excellent airtightness.

In addition, the tire inner liner of the embodiment has a load of 3 kgf or less at 100% elongation at room temperature, a load of 6 kgf or less at 100% elongation after heat treatment at 180 ° C. for 10 minutes, and heat treatment at 180 ° C. for 10 minutes. The load generated at 100% elongation afterwards was less than twice the load generated at 100% elongation at room temperature. Accordingly, even when a small force is applied when the tire is molded, it may be easily elongated or deformed, and may maintain a constant physical property even after the heat treatment step, and thus may exhibit excellent molding characteristics, and may occur during tire molding or driving of a vehicle. Physical properties can be stably maintained even in severe deformation.

On the contrary, the tire innerliner film of the comparative example shows a considerably high air permeability when the thickness is the same as that of the example, or a considerably larger load is generated in the case of 100% elongation at room temperature or 100% elongation after the heat treatment. The load generated at 100% elongation after heat treatment at 180 ° C. for 10 minutes was found to exceed twice the load generated at 100% elongation at room temperature.

Experimental Example 3 . Ease of Molding Measurement

Tires were manufactured by applying tire inner liner films of Examples and Comparative Examples to 205R / 65R16. During the tire manufacturing process, the manufacturing ease and appearance were evaluated after the manufacturing of the green tire, and then the final appearance of the tire was examined at the time when the manufacturing process was completed.

At this time, the green tire or the tire in the final state is not crushed, and if the standard deviation of the diameter is within 5% was evaluated as 'good'. If the tire is not properly manufactured due to dents in the green tire or the tire in the final state, or the inner liner inside the tire is melted or torn and broken, or if the standard deviation of the diameter exceeds 5%, it is evaluated as 'poor shape'. It was.

Experimental Example 4 . Air pressure retention performance measurement

The tires produced in Experimental Example 3 were compared and evaluated by measuring the IPR internal pressure retention (IPR Internal Pressure Retention) at a temperature of 21 DEG C under a pressure of 101.3 kPa for 90 days using the ASTM F1112-06 method.

The measurement results of Experimental Examples 3 to 4 are shown in Table 2 below.

Experimental Example 3 to  4, measurement results Example 1 Example 2 Example 3 Example 4 Example 5 Comparative Example 1 Comparative Example 2 Example 3 Green Tire Manufacturing Status Good Good Good Good Good Bad shape Good Bad shape Final tire status Good Good Good Good Good - Good - Air Pressure Reduction Rate (%) 2.6 3.0 2.4 2.8 1.9 - 8.8 -

As shown in Table 2, when the tire innerliner film of the embodiment is applied, even if the expansion pressure is applied in the tire manufacturing process, sufficient stretching can be achieved, it was shown that the manufacturing state of the green tire is good. In addition, when the tire inner liner of the embodiment is applied, it has been confirmed that it is possible to provide a tire in a final product state of good quality without occurrence of defects.

On the contrary, when the film for tire innerliner of the comparative example is applied, the load generated during the initial stretching is too large, and even when the expansion pressure is applied, the drawing of the green tire is deteriorated due to insufficient stretching. In addition, it was confirmed that the load generated after the heat treatment process was greatly increased or the physical properties of the inner liner film were reduced, making the final tire difficult.

On the other hand, as shown in the results of Experimental Example 4, a tire manufactured using the tire innerliner film of the embodiment is a tire to which the tire innerliner film was applied at 21 ° C. and 101.3 kPa conditions according to ASTM F1112-06. When 90 days of internal pressure retention (IPR) is measured, the air pressure reduction rate is maintained at less than 5%, thereby preventing overturning accidents and fuel economy lowering caused by low air pressure.

Tread
2. shoulder
3. Side Wall
4. CAP PLY
5. Belt
6. Body Ply
7. Inner Liner
8. Apex
9. BEAD

Claims (16)

Copolymers including polyamide-based segments and 5-50% by weight of polyether-based segments based on the total weight of the film; And polyamide-based resins;
Having a thickness of 30 to 300 μm,
A film for tire innerliner wherein the load generated at 100% elongation after heat treatment at 180 ° C. for 10 minutes is not more than twice the load generated at 100% elongation at room temperature.
The method of claim 1,
A film for tire innerliner with a load generated at 100% elongation after heat treatment at 180 ° C for 10 minutes at 6 kgf or less.
delete The method of claim 1,
The polyamide-based segment,
Nylon 6, Nylon 66, Nylon 46, Nylon 11, Nylon 12, Nylon 610, Nylon 612, Copolymer of Nylon 6/66, Nylon 6/66/610 Copolymer, Nylon MXD6, Nylon 6T, Nylon 6 / 6T Copolymer 1 type selected from the group consisting of nylon 66 / PP copolymer, nylon 66 / PPS copolymer, methoxymethylate of 6-nylon, methoxymethylate of 6-610-nylon and methoxymethylate of 612-nylon The film for tire innerliners containing the repeating unit of polyamide-type resin of this.
The method of claim 1,
The polyamide-based segment is a film for tire innerliner comprising a repeating unit of the following formula (1) or (2):
[Chemical Formula 1]

In Formula 1,
R ₁ is a straight or branched chain alkylene group having 1 to 20 carbon atoms or a straight or branched chain arylalkylene group having 7 to 20 carbon atoms,
(2)

In Chemical Formula 2,
R ₂ is a linear or branched alkylene group having 1 to 20 carbon atoms,
R ₃ is a straight or branched chain alkylene group having 1 to 20 carbon atoms or a straight or branched chain arylalkylene group having 7 to 20 carbon atoms.
The method of claim 1,
The polyether-based segment is a tire innerliner film comprising a repeating unit of the following formula (5):
[Chemical Formula 5]

In Chemical Formula 5,
R ₅ is an 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 are a direct bond, -O-, -NH-, -COO- or -CONH-, respectively.
The method of claim 1,
The polyether segment,
It includes a repeating unit of one polyether resin selected from the group consisting of polyethylene glycol, polypropylene glycol, polytetramethylene glycol, polyoxyethylene diamine, polyoxypropylene diamine, polyoxytetramethylene diamine and copolymers thereof Film for tire inner liner.
The method of claim 1,
Film for tire inner liner which is an unstretched film.
The method of claim 1,
A film for tire innerliner having an oxygen permeability of 200 cc / (m 2 · 24hr · atm) or less.
The method of claim 1,
A film for tire innerliner, which is formed on at least one surface of the film and further comprises an adhesive layer comprising a resorcinol-formalin-latex (RFL) adhesive.
delete The method of claim 1,
Tire innerliner film further comprises at least one additive selected from the group consisting of a heat resistant antioxidant and a heat stabilizer.
Polyamide-based resins or precursors thereof; And forming a copolymer by polymerizing 5 to 50 wt% of a polyether resin based on the total weight of the film; And
Method for producing a film for tire innerliner of claim 1 comprising the step of mixing the copolymer and polyamide-based resin to melt and extrude at 230 ℃ to 300 ℃ to form a film.
The method of claim 13,
The film is a method for producing a film for tire innerliner is an unstretched film having a thickness of 30 to 300 ㎛.
The method of claim 13,
And forming an adhesive layer comprising a resorcinol-formalin-latex (RFL) -based adhesive on at least one surface of the film formed from the melt extrudate.


delete

Images