JPS61148249A - Rubber composition and additive therefor - Google Patents

Abstract

PURPOSE:To obtain a rubber composition having remarkably improved cut resistance and chipping resistance, by compounding a rubber with a thermally polymerized cyclopentadiene-type petroleum resin having specified concentration ratio of norbornene ring double bond to cyclopentene ring double bond. CONSTITUTION:100pts.(wt.) of a diene polymer (e.g. natural rubber, poly butadiene, etc.) is compounded with 5-40pts., preferably 5-20pts. of a thermally polymerized cyclopentadiene-type petroleum resin wherein the concentration ratio of the norbornene ring double bond to the cyclopentene ring double bond is <=0.4 and the ratio of the copolymerizable olefinic hydrocarbon to cyclopentadiene is <=10wt%.

Description

[Detailed description of the invention]

(Industrial Application Field) The present invention relates to rubber compounding materials made of thermally polymerized cyclopentadiene petroleum resins having a concentration ratio of norbornene ring double bonds to cyclopentene ring double bonds of 0.40 or less, and the use of the same. The present invention relates to a rubber composition blended with a diene polymer. The rubber composition has significantly improved cutting and chipping resistance. 0T for large tires such as highway buses and trucks, and for civil engineering construction.
Since R (Off The Road) tires are usually used under harsh conditions, these tires are constantly subjected to high loads, which often causes cutting or chipping of the tire tread due to collisions with rocks, etc. This is a safety issue. (Prior art) Improvements in cut resistance and chip resistance have been developed for a long time, and natural rubber, styrene-butadiene rubber (S
It has been proposed to select an optimal diene polymer such as BR) or to add a petroleum resin mainly composed of dicyclopentadiene as a reinforcing agent. Japanese Patent Publication No. 48-38615 uses a dicyclopentadiene resin, and Japanese Patent Publication No. 52-43664 uses a dicyclopentadiene resin modified with a phenol resin.
No. 18938 discloses that the cut resistance and chip resistance of a tire tread can be improved by blending a dicyclopentadiene-oxystyrene copolymer with SBR or natural rubber, respectively. However, none of these methods should be fully satisfied, and even higher tire performance is required, especially as today's traffic volume increases dramatically and vehicle usage conditions become more severe. (Problems to be Solved) An object of the present invention is to provide a rubber composition exhibiting even better cut resistance and chip resistance, and a compounding material used therein. To evaluate the degree of cutting or chipping caused by collision or friction between the tire tread rotating at high speeds or under high load and rocks, etc., complex tests such as actual driving tests, simulation tests using miniature tires, or impact cut tests are necessary. Practical performance tests are required, which requires a great deal of cost, effort, and time. However, the above-mentioned three patent publications teach a tensile test method as a laboratory evaluation method for this performance, and it has also been confirmed that this test method correlates well with practical performance. A tensile test is a method of showing the elastic energy properties of a rubber composition by measuring the elongation and stress of the rubber composition. This test method is a well-understood method considering that the degree of cutting and chipping in the tire tread depends on how much energy the tire tread absorbs due to collisions with rocks and the like. 1 Therefore, in other words, the object of the present invention is to have greater elastic energy properties, i.e., room temperature and high il! (100℃)
The object of the present invention is to provide a rubber composition that exhibits a larger stress value and elongation, particularly a rubber composition that exhibits excellent tensile stress, and a compounding material used therein. Such a rubber composition having excellent tensile stress at room temperature and high temperature is particularly effective for the tire tread portion, which is susceptible to constant high loads. (Means for Solving the Problem) The present inventors have conducted intensive studies on various petroleum resins for use in rubber compositions, and have developed and improved them. As a result, the concentration ratio of norbornene ring double bonds to cyclopentene ring double bonds is 0.
．． The present invention was completed by discovering that a cyclopentadiene petroleum resin adjusted to have a molecular weight of 40 or less exhibits even greater blending effects. That is, the gist of the present invention is to provide a rubber composition in which a diene polymer is blended with a thermally polymerized cyclopentadiene petroleum resin in which the concentration ratio of norbornene ring double bonds to cyclopentene ring double bonds is 0.40 or less. It consists in rubber compounding materials made of petroleum resins as well as petroleum resins mentioned above. The ratio of the norbornene ring double bond to the cyclopentene ring double bond is determined by the hydrogen nuclear magnetic resonance spectrum (NMR) of the sample.
Measure the area ratio (concentration ratio) of the peak based on the proton of the norbornene ring double bond near about 5.9 ppm (δ) to the peak based on the proton of the cyclopentene ring double bond near about 5.6 ppm (δ). required. That is, the above-mentioned cyclopentadiene-based petroleum resin used in the compounding material and composition of the present invention has the above-mentioned area ratio in the nuclear magnetic resonance spectrum of 0.40 or less. The cyclopentadiene petroleum resin having the above characteristics can be produced by a conventional method by appropriately selecting conditions without requiring any special treatment. That is, the cyclopentadiene petroleum resin used in the present invention is produced by a conventional method, and the concentration ratio of norbornene ring double bonds and cyclopentene ring double bonds is determined according to thermal polymerization conditions, solvent removal conditions, or as desired. It is mainly controlled by appropriately setting the polymerization conditions of each step. The details will be described below. The cyclopentadiene-based petroleum resin referred to in the present invention is a petroleum resin thermally polymerized with cyclopentadiene, dicyclopentadiene, alkyl substituted products thereof, or a mixture thereof as a main component. Copolymer resins with 1/fin hydrocarbon compounds are also included. The olefins copolymerizable with the cyclopentadiene mentioned here include aliphatic olefins such as isoprene, 1,3-pentadiene, butadiene, and butenes, alicyclic olefins such as cyclopentene, vinyl olefins such as oyohistyrene, and vinyltoluene. Examples include substituted aromatic hydrocarbons or mixtures thereof. In addition, considering the elastic energy characteristics, the number of copolymerizable olefin hydrocarbons is 1 per cyclopentadiene.
Less than 0% by weight is preferred. Furthermore, considering aspects such as ease of polymerization and polymer yield, it is preferable that the ratio of the above-mentioned copolymerizable olefins to cyclopentadiene in the raw material monomer mixture is less than 10% by weight. Such polymerization of cyclopentadines is carried out at 200 to 350°C, preferably 240 to 300°C, using a batch system or continuous system in the presence or absence of a solvent such as xylene, toluene, n-hexano, or kerosene. It is generally carried out at a temperature range of 0.1 to 10 hours. The range of polymerization temperature and polymerization time in which the concentration ratio of norbornene ring double bonds to cyclopentene ring double bonds is 0.40 or less varies greatly depending on the type of cyclopentadiene, concentration, type of solvent, etc. Although not set specifically, the concentration ratio generally decreases as the polymerization conditions become more severe. Generally speaking, 4°5 at relatively low temperatures.
A petroleum resin having a desired concentration ratio can be obtained with a polymerization time of about 1 to 2 hours when the temperature is relatively high. The same thing can be inferred when the second stage thermal polymerization is subsequently carried out at a low temperature in the presence of a solvent. The solvent removal conditions essentially do not affect the concentration ratio of norbornene ring double bonds to cyclopentene ring double bonds, but mainly contain dimers and trimers that are entrained during the removal of solvent and unreacted monomers. The amount of relatively low molecular weight oligomers varies depending on the removal conditions, and as a result, the concentration ratio of norbornene ring double bonds and cyclopentene ring double bonds varies. Therefore, it is possible to adjust the double bond concentration ratio of the product by setting the removal conditions. Furthermore, the concentration ratio of norbornene ring double bonds to cyclopentene ring double bonds can also be reduced by performing a second thermal polymerization after removing the solvent. That is, as the second stage thermal polymerization progresses, the concentration ratio of the double bonds decreases. In addition to setting these manufacturing conditions, the concentration ratio of norbornene ring double bonds to cyclopentene ring double bonds can also be controlled by using chemical species or masking agents that selectively react with the norbornene ring double bonds in the product. It can be adjusted to 0.40 or less. The cyclopentadiene petroleum resin is a diene polymer 1o
O! Generally 5 to 40 overlapped parts per it part, preferably 5 to 40 overlapped parts
20tlt part is blended. Further, the "diene thread polymer" of the present invention includes natural rubber, polybutadiene rubber, styrene-butadiene rubber, imprene rubber, etc., and mixtures thereof. (Effects of the Invention) Although the compounded material of the present invention is extremely easily manufactured and has a scaly substance, it has an excellent compounding effect, and has better cut resistance and chip resistance than the conventionally used cyclopentadiene petroleum resin compound. It can easily be improved by about 10% or more. (Examples) The present invention will be explained in more detail below with reference to Examples, but the present invention is not limited by these. The formulation is standard as shown in Table 1, and all proportions are in parts by weight. The vulcanization accelerators used in the formulation are also common. Mixing was carried out using a roll method using a normal method (JIS K6383), and physical properties such as tensile strength, 300% tensile stress, tensile elongation, and hard spring type JIS A type were all evaluated according to the method of Tl5K6301. Standard example 1 contains petroleum resin as a softener.

Comparative Example 1 is an example of a cyclopentadiene petroleum resin in which the concentration ratio of the norbornene ring double bond to the cyclopentene ring double bond is greater than 0.40, which was polymerized by a conventional method. Reference Example] is an example of a commercially available petroleum resin containing cyclopentadiene and methylcyclopentadiene as main components. Comparative Example 1 Dicyclopentadiene 6001I with a dicyclopentadiene concentration of 84% by weight obtained from steam cracking of naphtha and 400 g of xylene were charged into an autoclave with an internal volume of 3 mm, and heated to 250 g while stirring under a nitrogen atmosphere.
The mixture was held at ℃ for 3 hours to carry out polymerization. Immediately after the reaction was completed, the reaction system was cooled and the product was taken out. Xylene, unreacted cyclopentadiene, etc. were removed from the polymerization product by vacuum distillation at 190°C to obtain cyclopentadiene resin 307I having a softening point of 97°C. The concentration ratio of norbornene ring double bonds to cyclopentene ring double bonds in the resin was 0.62. Reference Example 1 Commercially available rubber compound made of petroleum resin (manufactured by Exxon)
was used. Analysis of the petroleum resin using an electrolytic desorption mass spectrometer revealed that its main components were cyclopentadiene and methylcyclopentadiene. The concentration ratio of norbornene ring double bonds to cyclopentene ring double bonds was 0.46. Example 11 Thermal polymerization was carried out at 270° C. for 2 hours in the same manner as in Comparative Example 1. After that, the solvent was removed at 160°C and the softening point was 96.
C. Petroleum resin 42011 was obtained. The concentration ratio of norbornene ring double bonds to cyclopentene ring double bonds in the petroleum resin was 0.33. Example 2 Thermal polymerization was carried out at 280° C. for 2 hours in the same manner as in Comparative Example 1. Thereafter, the solvent and the like were removed under mild conditions at 140°C to obtain a petroleum resin 480.9 having a softening point of 92°C. The concentration ratio of norbornene ring double bonds to cyclopentene ring double bonds was 0.38. Example 3 Thermal polymerization was carried out at 260° C. for 2 hours in the same manner as in Comparative Example 1. Thereafter, after removing the solvent and the like at 210°C, polymerization was further carried out at 240°C for 1 hour. 270g of petroleum resin with a softening point of 1140℃
I got it. The concentration ratio of norbornene ring double bonds to cyclopentene ring double bonds was 0.31. Tensile tests were conducted on rubbers blended with the cyclopentadiene resins obtained in Comparative Example 1 and Examples 1 to 3, and the commercially available cyclopentadiene resin of Reference Example 1, respectively. The compounding ratio of the rubber composition is shown in Table 1, and the physical properties of the rubber after vulcanization are shown in Table 2. It is understood that the petroleum resins of Examples 1 to 30 clearly have better elastic energy properties than the petroleum resins of Comparative Example 1 and Reference Example 1. 1 Table 5BR-1500100] i parts Zinc white No. 1 5.0 Stearic acid 3.01 Sulfur 2.01 Vulcanization accelerator MB
T8 1.0# 'D'PG O,5NHAF carbon black 50 1 Manufacturer name SBR1500: Japan Synthetic Rubber ■ Zinc white No. 1: Sakai Chemical Industry ■ Stearic acid: East Japan Chemical ■ Sulfur: Hosoi Chemical Industry ■ Vulcanization Accelerator MB
TS: Iriuchi Shinko Chemical Industry ■ DPG: HAF Carbon Black (Asahi 70): Asahi Carbon ■

Claims (4)

[Claims] (1) A rubber composition prepared by blending a thermally polymerized cyclopentadiene petroleum resin with a diene polymer in which the concentration ratio of norbornene ring double bonds to cyclopentene ring double bonds is 0.40 or less. (2) The composition according to claim 1, wherein the proportion of copolymerizable olefin hydrocarbons per cyclopentadiene in the cyclopentadiene petroleum resin is less than 10% by weight. (3) A compound material for rubber comprising a thermally polymerized cyclopentadiene petroleum resin in which the concentration ratio of norbornene ring double bonds to cyclopentene ring double bonds is 0.40 or less. (4) The rubber compound according to claim 3, wherein the proportion of copolymerizable olefin hydrocarbons per cyclopentadiene in the cyclopentadiene petroleum resin is less than 10% by weight.