KR102167584B1 - Phenolic Synthetic Resin and Rubber Composition for Tire Tread Comprising the Same - Google Patents

Abstract

The present invention relates to a phenol-based synthetic resin and a rubber composition for a tire tread containing the same, and more specifically, the phenol-based synthetic resin according to the present invention remarkably improves physical properties such as grip while maintaining mechanical properties as it is, It has an advantage that can be usefully used in manufacturing high-performance tires.

Description

Phenolic Synthetic Resin and Rubber Composition for Tire Tread Comprising the Same}

It relates to a phenolic synthetic resin and a rubber composition for a tire tread comprising the same.

In recent vehicle evaluations, the braking distance of the vehicle has emerged as a major performance evaluation item, and vehicle users are also frequently exposed to information on vehicle accidents. have.

There are various characteristics required for vehicle tires, including durability, wear resistance, rolling resistance, fuel economy, steering stability, ride comfort, braking, vibration, and noise. Recently, as vehicles have become more advanced and safety requirements are increasing, there is a need to develop high-performance tires capable of maintaining optimal performance in various road surfaces and climates.

The rubber constituting the tire is generally a'viscoelastic body' that has both elasticity and viscosity. As the tire rotates, it rubs against the road surface and periodically repeats deformation and recovery. At this time, the energy during deformation is not completely recovered due to the viscosity of the tire, and some of it is consumed as thermal energy. This thermal energy is called hysteresis loss, and when the loss is large,'hysteresis is High'. High hysteresis means that the Tanδ value of DMA data is high, so a method of predicting hysteresis characteristics of rubber compositions by measuring DMA is widely used in the tire industry.

The excellent grip means that the tire and the road surface have high adhesion, which means good braking performance when cornering or stopping. In the physical sense, the hysteresis of the tire composition is high, so it absorbs the deformation energy received from the outside and consumes a lot of heat energy. On the other hand, as the heat energy is consumed, the conversion rate to the driving force decreases, and the rolling resistance (R/R, rolling resistance) increases. In this way, the tire must satisfy the contradictory aspect of improving fuel economy by reducing R/R while securing braking by increasing grip.

However, in reality, the external conditions required for the expression of these characteristics in the tire, that is, the temperature range are different, and can be overcome to some extent through optimization of the rubber composition for each tire part. For example, the grip force is divided into the wet grip force and the dry grip force, and the wet grip force measures the grip force when wet by snow or rain. The dry grip force refers to the grip force in the general road surface condition.

Therefore, in order to develop a rubber composition for the tread part to improve grip, it maintains a balance between wet grip and dry grip, while minimizing the overall improvement effect and the expected increase in R/R. I need it.

There are various methods for developing a rubber composition for the tread part to improve grip, but it can be largely divided into the development of rubber (SBR), fillers (carbon black, silica, etc.), and other additives.

In general, when the content of carbon black in the rubber composition is increased or the styrene content of styrene-butadiene rubber (SBR) is increased, the glass transition temperature (Tg) of the composition is increased and the grip is improved, but the rolling resistance is increased, resulting in fuel economy. There is a drawback that is lowered and crack resistance deteriorates.

In addition, when silica is mixed with carbon black as a filler, it can be seen that the wet grip is improved, but abrasion resistance and dry grip are deteriorated. As such, it is essential to consider the balance of physical properties, as the improvement of the grip power can lead to the deterioration of the existing required properties, and there is a limit to controlling the rubber (SBR) and filler.

As a technology for improving the grip, Korean Patent Laid-Open No. 10-2011-0036495 "Tread rubber composition and pneumatic tire", Korean Patent Laid-Open No. 10-2012-0115227 "Rubber composition for tire and pneumatic tire"", Republic of Korea Patent Publication No. 10-1356565, "a rubber composition for a tire tread and a tire manufactured using the same", etc. are disclosed.

Korean Patent Application Publication No. 10-2011-0036495 Korean Patent Application Publication No. 10-2012-0115227 Republic of Korea Patent Publication No. 10-1356565

The main object of the present invention is to provide a method of manufacturing a phenolic synthetic resin capable of improving physical properties such as grip while maintaining the mechanical properties of a tire as it is.

Another object of the present invention is to provide a rubber composition for a tire tread capable of improving the grip of a tire while maintaining mechanical properties, including a phenolic synthetic resin prepared by the above manufacturing method.

Another object of the present invention is to provide a tire comprising rubber made of the rubber composition for a tire tread.

In order to achieve the above object, an embodiment of the present invention is to produce a phenol intermediate by reacting phenols and formaldehyde in the presence of a catalyst (P1); And it provides a method for producing a phenolic synthetic resin used in a rubber composition for a tire tread comprising the step (P2) of melting and mixing by adding a petroleum resin to the produced phenolic intermediate.

In a preferred embodiment of the present invention, the catalyst may be one or more selected from the group consisting of an organic acid catalyst and an inorganic acid catalyst.

In a preferred embodiment of the present invention, the organic acid catalyst is at least one selected from the group consisting of oxalic acid and acetic acid, and the inorganic acid catalyst is selected from the group consisting of trifluoromethane sulfonic acid, fluorosulfonic acid, sulfuric acid, hydrochloric acid and nitric acid. There may be more than one type.

In a preferred embodiment of the present invention, the phenols may be one or more selected from the group consisting of phenol and alkylphenol.

In a preferred embodiment of the present invention, the formaldehyde and phenols may be added in a ratio of 1 mol: 1.05 mol to 1 mol: 1.80 mol.

In a preferred embodiment of the present invention, the step of producing the phenol-based intermediate may include an unreacted phenol content of 3% or less.

In a preferred embodiment of the present invention, the phenolic intermediate may have a weight average molecular weight of 800 to 1500 g/mol and a softening point of 90 to 150°C.

In a preferred embodiment of the present invention, the petroleum resin may be one or more selected from the group consisting of C5 petroleum resin, C9 petroleum resin, and hydrogenated (hydrogenated) petroleum resin.

In a preferred embodiment of the present invention, the petroleum resin may have a weight average molecular weight of 800 to 1500 g/mol and a softening point of 90 to 150°C.

In a preferred embodiment of the present invention, the petroleum resin may be added in an amount of 20 to 80 parts by weight based on 100 parts by weight of the phenolic intermediate.

In a preferred embodiment of the present invention, the phenolic synthetic resin may have a weight average molecular weight of 829 to 2000 g/mol and a softening point of 90 to 150°C.

Another embodiment of the present invention provides a rubber composition for a tire tread comprising a phenolic synthetic resin prepared by the above manufacturing method.

In another preferred embodiment of the present invention, the phenolic synthetic resin may have a weight average molecular weight of 829 to 2000 g/mol and a softening point of 90 to 150°C.

In another preferred embodiment of the present invention, the rubber composition for a tire tread may include 3 to 30 parts by weight of a phenolic synthetic resin based on 100 parts by weight of rubber.

Another embodiment of the present invention provides a tire comprising a rubber made of the rubber composition for a tire tread.

The phenolic synthetic resin according to the present invention can be usefully used in manufacturing high-performance tires by remarkably improving physical properties such as grip while maintaining the mechanical properties of the tire as it is.

Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by an expert skilled in the art to which the present invention belongs. In general, the nomenclature used in this specification is well known and commonly used in the art.

Throughout the specification of the present application, when a certain part "includes" a certain component, it means that other components may be further included rather than excluding other components unless otherwise stated.

In one aspect, the present invention provides a step (P1) of reacting phenols with formaldehyde in the presence of a catalyst to produce a phenolic intermediate; And it relates to a method for producing a phenolic synthetic resin used in a rubber composition for a tire tread comprising the step (P2) of melting and mixing by adding a petroleum resin to the produced phenolic intermediate.

Hereinafter, the present invention will be described in detail.

First, in the method for producing a phenolic synthetic resin according to the present invention, a phenolic intermediate is produced by reacting phenols with formaldehyde in the presence of a catalyst (P1).

According to a preferred embodiment of the present invention, the phenols may be one or more selected from the group consisting of phenol and alkylphenol, and in particular, it is preferable to use PTOP (Para-Tertiary Octylphenol) and PTBP (Para-Tertiary Butylphenol). It is preferable in terms of improving the compatibility of rubber and resin and reactivity with formaldehyde.

The formaldehyde and phenols may be added in a ratio of 1 mol: 1.05 mol to 1 mol: 1.80 mol. If phenols are used in less than 1.05 moles relative to 1 mole of formaldehyde, the molecular weight and softening point are low, and when used in a rubber composition, desired physical properties such as improved grip cannot be expected, and phenols are 1.80 moles relative to 1 mole of formaldehyde. If it is exceeded, the molecular weight and softening point become unstable due to excessive reactivity, which may cause difficulty in quality control.

According to a preferred embodiment of the present invention, the catalyst used in the reaction of the phenols and formaldehyde may be one or more selected from the group consisting of an organic acid catalyst and an inorganic acid catalyst. The organic acid catalyst may be one or more selected from the group consisting of oxalic acid and acetic acid, and the inorganic acid catalyst may be one or more selected from the group consisting of trifluoromethane sulfonic acid, fluorosulfonic acid, sulfuric acid, hydrochloric acid and nitric acid. Among them, it is preferable to use oxalic acid from the viewpoint of reactivity between phenols and formaldehyde.

The content of the catalyst is preferably used in an amount of 0.5 to 1.5 parts by weight based on 100 parts by weight of phenols. When the content of the catalyst is used within the above range, it is easy to control the heat of reaction and has the advantage of realizing stable physical properties. In addition, when the amount is less than 0.5 parts by weight, the reactivity is significantly lowered, and it is difficult to obtain the desired molecular weight and softening point. When the amount exceeds 1.5 parts by weight, the reaction rate increases, making temperature control difficult.

The reaction between the phenols and formaldehyde may be performed at 95° C. to 120° C. for 4 to 8 hours, and then degassed at atmospheric pressure to remove moisture until the occurrence of bubbles disappears, thereby producing a phenolic intermediate. When the reaction between the phenols and formaldehyde is carried out under the above conditions, the reaction can be stably carried out while controlling the heat of reaction. In addition, the main reaction time is preferably carried out in 4 to 8 hours so as to be designed according to the desired final molecular weight.

According to a preferred embodiment of the present invention, the step of producing the phenolic intermediate satisfies that the content of unreacted phenols is 3% or less, so that the dispersion effect is excellent when the rubber composition is blended, and the physical properties of the rubber composition such as Tanδ are increased. It works. If the content of unreacted phenol is more than 3%, the amount of unreacted material volatilized during the manufacture of the rubber composition increases, so that the desired physical properties cannot be obtained, and workability is adversely affected.

In addition, the phenolic intermediate produced from the above has a weight average molecular weight of 800 to 1500 g/mol, a softening point of 80 to 150°C, and a weight average molecular weight and softening point satisfying the above ranges, so that the dispersion effect is excellent when compounding the rubber composition. , Tanδ, etc. have the effect of increasing the physical properties of the rubber composition.

When the reaction as described above is completed, petroleum resin is added to the resulting phenolic intermediate and then melt-mixed (P2). In this case, in the P2 step, the catalyst added in the P1 step is used as it is without a neutralization process or a recovery process, so that the reaction process time can be shortened and generation of by-products can be reduced.

According to a preferred embodiment of the present invention, the petroleum resin added to the phenol intermediate may be one or more selected from the group consisting of C5 petroleum resin, C9 petroleum resin, and hydrogenated (hydrogenated) petroleum resin, among which hydrogen The use of an additive (hydrogenated) petroleum resin is preferable in terms of improving the Tanδ of the rubber composition in a specific temperature range.

In addition, it is preferable to use the petroleum resin having a weight average molecular weight of 800 to 1500 g/mol and a softening point of 90 to 150° C. in terms of compatibility with an intermediate and satisfying the molecular weight and softening point range of the final resin.

In addition, the content of the petroleum resin may be added in an amount of 20 to 80 parts by weight based on 100 parts by weight of the phenolic intermediate produced in step P1. If less than 20 parts by weight or more than 80 parts by weight with respect to 100 parts by weight of the phenolic intermediate, there may be a problem that the effect of improving the grip power of the rubber composition is halved.

When the petroleum resin is added to the phenolic intermediate and melt-mixed, the reaction may be carried out at 160 to 170° C. for 1 to 2 hours. When the process of melt-mixing by adding petroleum resin to the phenolic intermediate is performed under the above conditions, the mixing time can be shortened while maintaining the efficiency of melt-mixing, and the final molecular weight can be easily realized.

When the reaction is completed, a process of removing unreacted monomers by degassing under reduced pressure may be performed to obtain a phenol-based resin satisfying the final desired weight average molecular weight and softening point.

The phenolic synthetic resin prepared in this way has a weight average molecular weight of 829 to 2000 g/mol, a softening point of 90 to 150°C, and a weight average molecular weight and softening point satisfying the above ranges, so that the dispersion effect is excellent when compounding the rubber composition. , Tanδ, etc. have the effect of increasing the physical properties of the rubber composition.

In another aspect, the present invention relates to a rubber composition for a tire tread comprising a phenolic synthetic resin prepared by the above manufacturing method.

When the phenolic synthetic resin prepared as described above is used by including it in a rubber composition for a tire tread, it is possible to obtain an effect of improving grip by increasing hysteresis of the rubber composition.

Specifically, the rubber composition for a tire tread is used in rubber for manufacturing a tire tread, and since the tread contacts the road surface due to the structure of the tire, it is important to improve grip above all as a requirement of the tread. Tires (rubber compositions) are repeatedly deformed and recovered, and some of the energy input is converted into heat. This energy loss per transformation recovery is called hysteresis. The phenolic synthetic resin prepared by the above-described manufacturing method increases the hysteresis of the rubber composition for tire tread, and converts and absorbs a large amount of external energy into thermal energy during tire braking. This effect improves the grip.

In particular, the phenolic synthetic resin has a weight average molecular weight of 829 to 2000 g/mol, a softening point of 90 to 150°C, and contains a rubber composition for tire tread to increase hysteresis at room temperature, thereby increasing the dry grip of the general road surface among the grip strength. Can be improved.

The rubber composition for tire tread may include 3 to 30 parts by weight of a phenolic synthetic resin based on 100 parts by weight of rubber. At this time, when less than 3 parts by weight of a phenolic synthetic resin is included with respect to 100 parts by weight of the rubber, it is difficult to expect a visible effect of improving the grip power, and when it exceeds 30 parts by weight, the dispersion efficiency is low and it is difficult to implement uniform physical properties.

The rubber may include styrene-butadiene rubber alone as a raw material rubber, or at least one selected from styrene-butadiene rubber, styrene rubber, and butadiene rubber.

The rubber composition for a tire tread may include other compounding agents added to a conventional rubber composition for a tire tread, such as carbon black and silica as reinforcing agents; As a crosslinking accelerator, TBBS (N-Tert-butylbenzothiazole-2-sulfenamide), Ntert-butyl-2-benzolsulfenamide, CBS (n-cyclohexyl benzothiazyl-2-sulfenamide), etc.; Bis[3-(triethoxysilyl)]tetrasulfide as a silane coupling agent, 6,Dipropylene glycol as an activator, sulfur as a crosslinking agent, stearic acid, zinc oxide, etc.; As an anti-aging agent, N-1,3-dimethylbutylpoly 2,2,4-trimethyl, 1,2-dihydroquinoline, waxyhydrocarbon, and the like can be used.

According to another embodiment of the present invention, it is to provide a tire including rubber made of the above-described rubber composition.

The tire may be manufactured by using the above-described rubber composition and by adopting a method for manufacturing a tire generally known in the field to which the present invention belongs.

Hereinafter, preferred examples and comparative examples of the present invention will be described. However, the following examples are only preferred examples of the present invention, and the present invention is not limited to the following examples.

<Production Example 1> Preparation of phenolic synthetic resin

2,500 g of PTBP (Para-Tertiarybutylphenol) (SI Group) and 1,013 g of 37% formaldehyde (Alpha Chemika) were added to a glass reactor equipped with a stirrer, condenser, and nitrogen inlet, and dissolved at 80°C, followed by a catalyst. 15 g of oxalic acid (Daemyung Chemical) was added and a reflux reaction was carried out over 4 hours while stirring. After the reflux reaction was completed, atmospheric pressure degassed to 160° C. to remove moisture until bubbles disappeared, thereby obtaining a phenolic intermediate.

Next, 30 parts by weight of a hydrogenated (hydrogenated) petroleum resin (KOLON INDUSTRIS, SU-120) with a softening point of 120°C was added to the phenolic intermediate obtained from the above, completely dissolved, and degassed under reduced pressure to 180°C to remove unreacted monomers. After removal, a phenolic synthetic resin having a softening point of 117°C was prepared.

<Production Example 2> Preparation of phenolic synthetic resin

It was prepared in the same manner as in Preparation Example 1, except that 10 parts by weight of petroleum resin relative to the phenolic intermediate was added.

<Production Example 3> Preparation of phenolic synthetic resin

It was prepared in the same manner as in Preparation Example 1, except that 50 parts by weight of petroleum resin relative to the phenolic intermediate was added.

<Production Example 4> Preparation of phenolic synthetic resin

It was prepared in the same manner as in Preparation Example 1, except that 70 parts by weight of petroleum resin relative to the phenolic intermediate were added.

<Production Example 5> Preparation of phenolic synthetic resin

It was prepared in the same manner as in Preparation Example 1, except that 90 parts by weight of petroleum resin relative to the phenolic intermediate was added.

The physical properties of the phenolic synthetic resins prepared according to Preparation Examples 1 to 5 were measured by the following method, and the results are shown in Table 1 below.

(1) Softening point measurement

It was measured using Mettler Toledo's FT900 and 83HT at a rate of 5℃/min.

(2) molecular weight measurement

The phenolic synthetic resin prepared according to Preparation Examples 1 to 5 was dissolved in Tetra Hydro Furan (THF) at a concentration of 4000 ppm, and a weight average molecular weight (Mw) was used using a gel permeation chromatography (manufactured by Waters). And the number average molecular weight (Mn) was measured.

(3) Molecular weight dispersion (PDI) measurement

The weight average molecular weight (Mw) and number average molecular weight (Mn) measured in (2) are added to the number average molecular weight. It was calculated as the weight average molecular weight ratio.

division Manufacturing Example 1 Manufacturing Example 2 Manufacturing Example 3 Manufacturing Example 4 Manufacturing Example 5 Phenolic
Synthetic resin
Properties Softening point (℃) 117.0 116.0 118.5 118.6 119.0 Number average molecular weight (Mn) 576g/mol 575/mol 576g/mol 580mol 588mol Weight average molecular weight (Mw) 829g/mol 823g/mol 835g/mol 841g/mol 847g/mol Molecular weight dispersion (PDI) 1.44 1.43 1.45 1.45 1.44

<Example 1> Preparation of rubber specimen

Based on 100 parts by weight of rubber (styrene-butadiene rubber 70 + natural rubber 30), 55 parts by weight of silica, 10 parts by weight of carbon black, 6 parts by weight of Bis[3-(triethoxysilyl)]tetrasulfide, 3 parts by weight of zinc oxide, 1 stearic acid By weight, dipropylene glycol 1 part by weight, sulfur 2 parts by weight CBS (n-cyclohexyl benzothiazyl-2-sulfenamide) 1.5 parts by weight and 5 parts by weight of the phenolic synthetic resin prepared according to Preparation Example 1 were added to The pounding operation was carried out and vulcanized at 160° C. for 20 minutes to prepare a test rubber specimen.

<Example 2> Preparation of rubber specimen

It was carried out in the same manner as in Example 1, except that the phenol-based synthetic resin prepared according to Preparation Example 2 was used as a resin type.

<Example 3> Preparation of rubber specimen

It was carried out in the same manner as in Example 1, except that the phenol-based synthetic resin prepared according to Preparation Example 3 was used as a resin type.

<Example 4> Preparation of rubber specimen

It was carried out in the same manner as in Example 1, except that the phenol-based synthetic resin prepared according to Preparation Example 4 was used as a resin type.

<Example 5> Preparation of rubber specimen

It was carried out in the same manner as in Example 1, except that the phenol-based synthetic resin prepared according to Preparation Example 5 was used as a resin type.

<Example 6> Preparation of rubber specimen

It was carried out in the same manner as in Example 1, except that 10 parts by weight of the phenol-based synthetic resin prepared according to Preparation Example 1 was used as the resin type.

<Example 7> Preparation of rubber specimen

It was carried out in the same manner as in Example 1, except that 10 parts by weight of the phenol-based synthetic resin prepared according to Preparation Example 3 was used as the resin type.

<Example 8> Preparation of rubber specimen

It was carried out in the same manner as in Example 1, except that 10 parts by weight of the phenolic synthetic resin prepared according to Preparation Example 4 was used as the resin type.

<Comparative Example 1> Preparation of rubber specimen

Except for using 5 parts by weight of a phenol resin (KPH-F2002, KOLON INDUSTRIS) (softening point: 100°C, weight average molecular weight: 1746 g/mol) instead of the phenol-based synthetic resin prepared according to Preparation Example 1, It was carried out in the same way.

<Comparative Example 2> Preparation of rubber specimen

Example 1, except that 5 parts by weight of an alkylphenol resin (KPT-S1503, KOLON INDUSTRIS) (softening point: 95°C, weight average molecular weight: 1724 g/mol) was used instead of the phenol-based synthetic resin prepared according to Preparation Example 1. It was carried out in the same way as.

<Comparative Example 3> Preparation of rubber specimen

Example 1, except that 5 parts by weight of an alkylphenol resin (KPA-1350K, KOLON INDUSTRIS) (softening point: 112°C, weight average molecular weight: 1245 g/mol) was used instead of the phenol-based synthetic resin prepared according to Preparation Example 1. It was carried out in the same way as.

<Comparative Example 4> Preparation of rubber specimen

Example 1, except that 5 parts by weight of an alkylphenol resin (KPA-F1360, KOLON INDUSTRIS) (softening point: 139°C, weight average molecular weight: 1790 g/mol) was used instead of the phenol-based synthetic resin prepared according to Preparation Example 1. It was carried out in the same way as.

<Comparative Example 5> Preparation of rubber specimen

Except for the use of 5 parts by weight of petroleum resin (A-1100, KOLON INDUSTRIS) (softening point: 100°C, weight average molecular weight: 1736 g/mol) instead of the phenolic synthetic resin prepared according to Preparation Example 1 It was carried out in the same way.

<Comparative Example 6> Preparation of rubber specimen

Except for using 5 parts by weight of petroleum resin (P-90, KOLON INDUSTRIS) (softening point: 95°C, weight average molecular weight: 942 g/mol) in place of the phenolic synthetic resin prepared according to Preparation Example 1, and Example 1 It was carried out in the same way.

The physical properties of the rubber specimens prepared according to Examples 1 to 6 and Comparative Examples 1 to 6 were measured by the following method, and the results are shown in Table 2 below.

(1) Tensile force measurement

Tensile strength, elongation, and tensile stress are included in the stress-strain properties during tension. ISO 37, ASTM D412, BS 903: Part A2, DIN 53504 specifies a standard method for determining these properties. There are dumbbell type No. 1 to No. 4 for test specimens, and No. 3 is mainly used. (Type 1 for low elongation, type 2 for low tensile strength, type 4 for pure rubber blended and latex products). The thickness should be 2 ~ 3mm. Tensile properties refer to tensile strength, elongation, and tensile stress. These properties are measured by pulling a standard specimen at a constant speed in a device called a tensile tester.

Tensile strength is the force or stress that is cut when a standard specimen is pulled at a constant speed, expressed in MPa, N/mm ² , kg/cm ² , and lb/cm ² . Each tensile strength of the rubbers are shown differently from below 7MPa (71kg / cm ²⁾ according to the used raw material rubber and compounding agents to more than 45MPa (451kg / cm ^2).

The definition of elongation or strain is the elongated length exhibited by the tensile force applied to a standard specimen, expressed as a percentage of the initial length. For example, 300% elongation means that the specimen has been stretched to four times its initial length. Elongation at break (Ultimate elongation or Elongation at break) represents the elongation at break, which is automatically obtained during tensile strength tests. The cutting elongation varies from 100% to 1000% depending on the rubber compound, but in rubber tests it usually means elongation or elongation.

Tensile modulus (tensile modulus) applied to rubber is defined as the force required to maintain a certain elongation and is expressed in MPa, N/mm ² , kg/cm ² , lb/cm ² , equal to tensile strength. Mainly measured tensile stress (modulus) is at 100% and 300% elongation. For example, if the force required to maintain 100% elongation is 5 MPa (51 kg·f/cm ² ), the 100% tensile stress is 5 MPa. Tensile stress represents the degree of stiffness and vulcanization of a rubber compound, usually obtained during tensile strength testing. The 100% tensile stress of other rubber compounds varies from 1 MPa (10.2 kg·f/cm ² ) or less to 13 MPa (133 kg·f/cm ² ) or more, depending on the chemical composition of the rubber compound.

The test temperature has a great influence on the results. Therefore, the temperature must be controlled and recorded in the measurement report. The standard laboratory temperatures specified in ISO 37 are [20(±2)°C, 23(±2)°C, 27(±2)°C]. The change in the elongation rate has a great influence on the tensile stress and elongation. As the elongation rate increases, the tensile stress increases, the elongation decreases, and the tensile strength may increase or decrease.

Tensile testing is useful for product management. In particular, the tensile strength changes very sensitively to any change in the rubber compound caused by manufacturing errors. Tensile testing is useful for measuring the resistance of rubber to aging caused by heat, liquids, gases, chemicals, ozone, and climate. For this purpose, the tensile strength, tensile stress, and elongation are measured before and after the exposure test. If these values are small, the service life is expected to be long.

-Device specifications and conditions

Model: U.T.M-Shimadzu AG-1S (Load cell: PFG-5kN)

Specimen Standard: Dumbbell No. 3

Test speed: 500mm/min

Measurement DATA: Load value (kgf), tensile force (kgf), elongation (%), modulus (kgf, 50%, 100%, 300%)

-Test order

① Psalm preparation

The specimen is cut according to the standard of Dumbbell No. 3 after relaxing the crosslinked rubber sheet by pressing for 24 hours or more. The point to note when cutting is that when pulling out a sheet with a certain thickness through open-roll work, it is necessary to mark the direction and cut it in a certain direction to reduce the deviation. Each cut specimen is recorded by measuring its thickness using a thickness meter.

② Program setting

Set the test type (for tensile measurement), test conditions (test speed, properties to be calculated), and calibrate the elongation and load values. In the case of an extensometer, calibration is required for every measurement.

In the case of flexible materials such as rubber, an elongation device is essential for measuring the elongation. If the load cell standard and program setting value do not match, the reliability of the data may be degraded, and caution must be exercised as the test equipment may be strained.

③ Specimen attachment and data processing

After entering the thickness value of each specimen measured with a thickness meter, the specimen is held in the grip of the U.T.M equipment. At this time, in consideration of the position of the extensor, the extensor is positioned so that it can fit within the measurement range of the specimen.

Basically, in the case of tensile force and modulus excluding the load value and elongation, the thickness of the specimen is reflected, so care must be taken when measuring the thickness.If the fracture surface exceeds the measurement method after the end of the test, mark it and compare it with the data to decide whether to process do.

(2) Measurement of hardness

The hardness of rubber is defined as the degree to which the surface resists indentor penetration of a specified size under a specified load. At the same time as the test, the hardness tester is classified into several types according to the indentation and loading method. It has a constant scale value that can be read right away, and the scale is randomly divided from 0 (for very flexible) to 100 (for hard), and the load is applied in the form of dead load and spring.

Hardness is expressed in IRHD (International Rubber Hardness Degrees) or Shore hardness degrees. The IRHD test is conducted based on the basic principle of measuring the degree of penetration of a ball of specified rigidity into a specimen under a constant specified static load. Shoa hardness testers, called Durometers, come in A and D types. The calibrated spring presses the prescribed pressure needle against the test piece. The Type A hardness tester has a blunt conical indenter and is used to measure the hardness of flexible rubber up to about 90 Shore A. The type A hardness tester and the type D hardness tester with other springs and pointed conical indentations are used to measure the hardness of hard materials over 90 Shore A.

The Shoa unit is almost the same as the IRHD unit, but it should not be converted directly because it can make a big difference. Most rubber products vary in hardness between 40 and 90 IRHD in practical use. Hardness of 40 or less can be obtained by adding a large amount of plasticizer when compounding rubber.

For thinner specimens, a micro IRHD instrument (a miniature version of the standard test) is used. The thickness of the standard specimen for micro test is 2.0(±0.2)mm. Thicknesses in this range are often consistent with the results of standard test methods using standard specimens. Thicker or silver specimens may be used, but in all cases they should be at least 1 mm thick. Measurements too close to the edge of the specimen may have a “edge effect.” In conclusion, the minimum distance from the edge by thickness is given in ISO 48, 1400, 1818. The hardness test is performed at standard laboratory temperatures [20 (±2). ℃, 23(±2)℃, 27(±2)℃] The test report includes (a) the size of the specimen, (b) the temperature, and (c) the type of surface to be measured (molding, polishing ( Buff), other), (d) The type of test equipment used shall be recorded.

All tests conducted on non-standard specimens are referred to as apparent hardness. Standard hardness refers to a test performed with a standard specimen [8-10mm for the standard test and 2.0(ㅁ0.2)mm for the micro test]. Elastic products made from the same material may have different apparent hardness depending on their shape and thickness. Test results obtained from curved surfaces (eg O-rings) are only arbitrary values applicable to a particular part and may show a difference of 10 or more in IRHD.

-Measuring equipment

Model: Shore Hardness Tester (Shore-A type)

Specimen standard: Vulcanized rubber sheet thickness 7mm±0.5mm

-Test order

① Psalm preparation

As for the specimen, the crosslinked rubber sheet is relaxed for more than 24 hours by pressing and then stacked in three layers to standardize the thickness. In the case of hardness, it is affected by the thickness of the specimen and should be at least 4mm, and it is recommended to be about 8mm to 10mm.

② Measurement of physical properties

Measure the crosslinked rubber sheet 5 times for each part and take the average value. Avoid measuring the edges of the crosslinked rubber sheet because there may be an edge effect when measuring physical properties.

(3) Measurement of abrasion

Abrasion resistance is defined as the resistance to abrasion by a moving rubber compound in contact with the wear surface. Wear is a very important property to consider when a rubber product is used in a dynamic state. Dynamic seals, for example, carry wear when moving on dry surfaces with relatively high friction.

The coefficient of friction of rubber is influenced by a number of factors such as the shape, composition, temperature, pressure, friction speed, and surface roughness of the rubber part and the mating material. Severe friction can be very bad as it generates heat that causes rubber deterioration. Such friction can also be significantly reduced with suitable lubricants or chemical treatment of the surface. Rubber compounds containing lubricants are sometimes used when minimal friction is required or when it is unclear whether the lubricant will continue to exist. The test methods are described in ISO 4649, ASTM D 2228 and D 1630, BS 903: Part A9, DIN 553516. In all of these test methods, a specimen of rubber compound is fixed against the wear surface under a specified load and speed. The volume loss of the rubber specimen is measured and the result is compared with the standard rubber and expressed as a percentage.

(4) Measurement of Dynamic Mechanical Analysis (DMA)

In Dynamic Mechanical Analysis, the mechanical analysis of a material is measured as a function of temperature, frequency, and vibration. When a periodic external force is applied to the sample, periodic stress is generated in the sample, and the sample reacts to this stress, resulting in a corresponding deformation. The mechanical modulus is determined from the stress and deformation at this time, and the Shear modulus (G) and Young's modulus (E) are measured according to the applied stress type. That is, a phase difference is generated according to a stress (usually sinusoidal stress) that changes periodically due to a time delay due to the viscoelastic properties of the material. The modulus dynamically measured in consideration of this phase difference is described as G'(Storage modulus) and G'' (Loss modulus). G'is the direct result of the DMA measurement, and is the in-phase response of the sample along with the periodic stress and corresponds to the reversible elasticity of the sample. The hypothetical component G'' is a phase shifted response of up to 90 ^O and corresponds to mechanical energy that is irreversibly lost as it is converted into heat. The tanδ of this phase difference is the Loss factor and is used to measure the damping behavior of the material. In the case of rubber, the higher Tanδ@0℃, Tanδ@25℃, and Tanδ@70℃, the better wet grip and dry grip, respectively, and the rolling resistance decreases.

-Device specifications and conditions

Model: TA-DMA Q800

Test Mode: Multi-Frequency-Strain

Clamp type: Tension-Film

Frequency: 11Hz

Preload force: 0.01N

Poisson's ratio: 0.44

Measurement range: -50℃ (hold for 5min) ~ 75℃, heating rate: 3℃/min

-Test order

① Psalm preparation

-The specimen is cut into 10±0.2(W, measured value)×12~13(L, automatic measurement)×2~2.5mm(measured value) after relaxing the crosslinked rubber sheet by pressing for 24 hours or more. Then enter the correct number.

-Basically, when cutting the specimen, the cut surface should be clean so that there is no significant difference in the dimensions of the specimen. When entering the dimension value, it is recommended to measure the dimension from several angles to enter the correct value.

② Calibration

-Calibration is basically divided into Position, Mass, and Compliance Calibration. Position with the clamp removed, the mass after installing the selected clamp, and the standard specimen, and finally the compliance calibration.

-Calibration is basically performed when the device is turned on for the first time, when liquid nitrogen is refilled and used, when the clamp is replaced and the test method is changed.

③ Specimen attachment

-Use a designated tool (small wrench) to attach the specimen to the clamp. The inside of the chamber is composed of various sensitive devices to drive the temperature sensor clamp, so be careful not to apply excessive force when using it.

④ Data processing

-All data is processed automatically, and after saving the file, G', G'' and Tanδ values according to the temperature change are obtained by the program. The Tg value of the rubber compound can be known through the maximum point of the Tanδ peak.

division Example Comparative example One 2 3 4 5 6 7 8 One 2 3 4 5 6 Mechanical properties Tensile strength at break (kgf) 208.82 205.32 207.89 206.84 202.21 205.57 205.70 208.01 204.55 204.59 205.66 203.12 202.71 202.85 Elongation at break (%) 310.99 307.10 308.29 312.50 310.53 306.71 308.52 307.21 310.28 310.12 311.52 308.56 309.33 309.45 Modulus (kgf) at 50% elongation 30.96 31.55 31.16 30.30 30.12 29.90 30.08 30.30 30.85 30.86 31.05 30.25 30.19 30.22 Modulus (kgf) at 100% elongation 59.48 59.32 59.15 57.96 57.25 56.11 60.77 62.50 57.84 57.85 58.12 57.12 57.01 57.85 Modulus (kgf) at 300% elongation 201.40 202.63 199.23 194.39 190.74 191.61 199.49 195.06 192.56 192.60 193.45 190.98 190.60 191.28 Hardness
(Shore A) 80 79 80 80 79 79 79 79 79 79 80 79 79 79 DIN Abrasion
(Loss weight) 0.358 0.395 0.355 0.351 0.388 0.370 0.383 0.382 0.395 0.385 0.378 0.387 0.389 0.381 DMA Tanδ
(0℃) 0.2505 0.2432 0.2636 0.2517 0.2421 0.2510 0.2644 0.2524 0.2427 0.2407 0.2386 0.2412 0.2417 0.2424 Tanδ
(25℃) 0.1952 0.1844 0.1983 0.1964 0.1582 0.1956 0.2089 0.2069 0.1862 0.1842 0.1821 0.1823 0.1543 0.1550 Tanδ
(70℃) 0.1892 0.1948 0.2023 0.1904 0.1433 0.1906 0.2040 0.1920 0.1961 0.1941 0.1920 0.1923 0.1431 0.1437 Tg(℃) -22.55 -22.98 -22.73 -22.12 -23.02 -21.15 -21.33 -21.02 -24.38 -24.52 -24.33 -24.26 -25.45 -25.89

As shown in Table 2, in Examples 1 to 8, the mechanical properties and abrasion are equal to or higher than those of Comparative Examples 1 to 6, while the Tan δ (0 °C) value and the Tan δ (25 °C) value It was confirmed that the glass transition temperature (Tg) was higher than that of Comparative Examples 1 to 6. Through this, it is expected to improve the wet grip and dry grip of the tire.

In addition, the Tandδ (70°C) values of Examples 1 to 8 are similar to those of Comparative Examples 1 to 4, and the characteristics of these rubber compositions can be expected to improve the grip of the tire without a significant decrease in rolling resistance characteristics.

All simple modifications or changes of the present invention can be easily implemented by those of ordinary skill in the art, and all such modifications or changes can be considered to be included in the scope of the present invention.

Claims (15)

Reacting phenols with formaldehyde in the presence of a catalyst to produce a phenolic intermediate (P1); And As a method for producing a phenolic synthetic resin for tire tread comprising the step (P2) of melting and mixing by adding a petroleum resin to the produced phenolic intermediate,
In the step (P1) of producing the phenol-based intermediate, the content of unreacted phenols is 3% or less.
The method of claim 1, wherein the catalyst is at least one selected from the group consisting of an organic acid catalyst and an inorganic acid catalyst.
The method of claim 2, wherein the organic acid catalyst is at least one selected from the group consisting of oxalic acid and acetic acid, and the inorganic acid catalyst is at least one selected from the group consisting of trifluoromethane sulfonic acid, fluorosulfonic acid, sulfuric acid, hydrochloric acid and nitric acid. A method for producing a phenolic synthetic resin, characterized in that.
The method of claim 1, wherein the phenols are at least one selected from the group consisting of phenol and alkylphenol.
The method of claim 1, wherein the formaldehyde and phenols are added in a ratio of 1 mol: 1.05 mol to 1 mol: 1.80 mol.
delete The method of claim 1, wherein the phenolic intermediate has a weight average molecular weight of 800 to 1500 g/mol and a softening point of 90 to 150°C.
The method of claim 1, wherein the petroleum resin is at least one selected from the group consisting of C5 petroleum resin, C9 petroleum resin, and hydrogenated (hydrogenated) petroleum resin.
The method of claim 1, wherein the petroleum resin has a weight average molecular weight of 800 to 1500 g/mol and a softening point of 90 to 150°C.
The method of claim 1, wherein the petroleum resin is added in an amount of 20 to 80 parts by weight based on 100 parts by weight of the phenolic intermediate.
The method of claim 1, wherein the phenolic synthetic resin has a weight average molecular weight of 829 to 2000 g/mol and a softening point of 90 to 150°C.
A rubber composition for a tire tread comprising a phenolic synthetic resin prepared by the manufacturing method of any one of claims 1 to 5 and 7 to 11.
The rubber composition for tire tread according to claim 12, wherein the phenolic synthetic resin has a weight average molecular weight of 829 to 2000 g/mol and a softening point of 90 to 150°C.
The rubber composition for tire treads according to claim 12, wherein the rubber composition for tire treads comprises 3 to 30 parts by weight of a phenolic synthetic resin based on 100 parts by weight of rubber.
A tire comprising a rubber made of the rubber composition for a tire tread of claim 12.