JPS6164738A - Rubber composition - Google Patents

Abstract

PURPOSE:To provide a rubber compsn. having excellent resiliece, tensile stress and flex cracking resistance and suitable for use in the production of tire tread, by blending carbon black with a modified polyisoprene rubber or a rubber mixture thereof with other diene rubber. CONSTITUTION:100pts.wt. polyisoprene rubber (a) is reacted with 0.0001-20pts. wt. glyoxylate ester (h) (e.g., ethyl glyoxylate) in the presence of 0.01-5mol (per mol of component h) of a Lewis acid (e.g., SnCl4) at -20-100 deg.C for 10sec to 10hr. If desired, after the completion of the reaction, the reaction product is hydrolyzed with an acid or an alkali to convert part or the whole of ester groups introduced into component (a) into COOH group, thus obtaining a modi fied polyisoprene rubber (A). 10-150pts.wt. carbon black having an average particle size of 10-500mmu and optionally additives such as vulcanizing agent, vulcanization accelerator, softening agent, antioxidant, filler, etc. are blended with 100pts.wt. rubber (mixture) consisting of 5-100wt% component A and 95-0wt% other diene rubber.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a rubber composition suitable for tires and the like that has excellent green strength and properties after vulcanization.

(Prior art) Conventionally, in order to obtain a rubber composition with improved green strength and adhesion, rubber into which a polar group such as a carboxy group has been introduced, such as maleic anhydride or glyoxol, has been added to carboxy rubber. It is known that rubber is used. However, these rubbers have the disadvantage that their strength properties as a vulcanizate are insufficient because rigid reactions such as rubber gluing and molecular weight reduction are likely to occur during the modification reaction. In particular, even if polar groups such as carboxyl groups are introduced into synthetic I-lisodelene/rubber rubber, which has a structure closest to that of natural rubber, by conventionally known methods, due to the above-mentioned drawbacks, It was difficult to use it for applications such as tires.

(Problems to be Solved by the Invention) Therefore, the present inventor conducted various studies in order to develop a modified polyisoterene rubber composition with excellent green strength and properties when made into a vulcanized product, and as a result, the present invention was developed. reached.

(Means for solving the problem) That is, it can be obtained by reacting glyoxylate ester with glyoxylic acid ester in the presence of a Lewis acid, or by hydrolyzing it after this reaction. A rubber composition prepared by blending 1°0 to 150 parts by weight of Cargon Plastic to 100 parts by weight of a rubber or rubber mixture containing 5 to 100% by weight of the resulting modified IR and 95 to 0% by weight of other diene rubbers. An object is provided by the present invention.

In the present invention, IR is defined to include not only synthetic 4-lisoprene rubber (hereinafter sometimes referred to as synthetic IR), but also natural rubber (hepya) having a polyisogrene structure, guanyl rubber, and the like.

In the present invention, the glyoxylic acid ester used is a compound represented by the general formula % (R is an aliphatic group, an alicyclic group, or an aromatic group). Here, the number of carbon atoms in R is preferably about 1 to 20 (although not limited).Also, the aliphatic group may be a straight chain or a side chain. Representative examples of the compounds include methyl glyoxylate, ethyl glyoxylate, isozolobyl glyoxylate, tert-butyl glyoxylate, benzyl glyoxylate, phenyl glyoxylate, octyl glyoxylate, and stearyl glyoxylate.Glyoxylate The amount of acid ester used is not particularly limited, but is usually 0 per part by weight of IRZoo.
．． 0001 to 20 parts by weight, preferably 0.01 to 5 parts by weight.

Generally known Lewis acids can be used in the present invention. Typical examples thereof are metal or metalloid halides, such as Be, B, At.

Sl , PeS , Tl +V, Fe tZn eGa
#G@, As tse, Zr eNb zoo
red ean, 8b pT@, Ta, w#ag
, gt aU or POr S eOrso
, so□, vO and other oxygen-element bond halodides or organic halodides, or complexes thereof. More specifically, BF s r BF 5o (CzH
5) 2 e(CH,)2BF , BCl, eAtct
, ,juBr 3. (C2H5)AtCA2. P.O.
Cl2゜T i C10,VC24eMOct6,5n
C14, (CH,)SnC1s, SbC15mTeCt
4 +T@Br4 eFect5 and wct6.

Of these, 5nCL4. BF, 0(C2H5)2. P
OCl3. TlCA4 etc. have a high reaction rate and IR
It is particularly suitable because there are few side reactions such as ru-formation.

The amount of Lewis acid used is not particularly limited, but is usually 0.01 to 1 mole of glyoxylic acid ester.
5 mol, preferably 05 to 2-enyl.

The reaction in the present invention is usually carried out in the presence of a suitable solvent or in the absence of a solvent in a mucus kneader. Industrially, it is advantageous to carry out the reaction in the rR cement after the polymerization has ended. When using a solvent, use Penda/,
Arbitrary solvents such as aromatic solvents such as toluene, sulfuric solvents such as butane and hexane, and halodanized hydrocarbon solvents such as chloroform and dichloroethane may be used, but they are inert to the reaction and A suitable material is one that dissolves .

The glyoxylic acid ester may be added to the reaction system in its entirety at the beginning, or may be added in portions or continuously during the reaction. Further, the Lewis acid may be added at the same time as the glyoxylic acid ester or separately, or the two may be mixed in advance and then added. When performing a reaction,
It is necessary to maintain the reaction system in an anhydrous state or under a limited amount of water.

The reaction temperature is not particularly limited and is usually -20°C.
~100°C, preferably -10°C to 60°C. The reaction time is also not particularly limited, and is appropriately set between 10 seconds and 10 hours.

After performing the above reaction for IR, it is also possible to hydrolyze with acid, alkali, etc. to convert some or all of the ester groups introduced into IH into karuxyl groups. This secondary reaction can also be carried out in solution or in a kneader.

When the reaction of the present invention is carried out in a solvent, the reaction can be stopped and the IR can be coagulated by pouring the reaction solution into a large amount of alcohol or hot water while stirring. Next, residues in the IR are removed by washing as necessary, and then dried to form a modified IR.
is obtained.

In the present invention, other diene rubbers that may be mixed with modified IR include natural comb rubber (hepya), guanyl rubber, synthetic IR, polybutadiene rubber (hereinafter referred to as BR), and styrene-butadiene copolymer rubber (hereinafter referred to as BR). Below SBR
), butadiene-piperylene copolymer rubber, butadiene-acrylonitrile copolymer rubber, isoprene-acrylonitrile copolymer rubber, high styrene/gum, ethylene-propylene-diene copolymer rubber, and the like.

It is of course possible to use two or more of these in combination.

These diene rubbers are selected depending on the application, but for tires, BR, SBR, natural rubber, BR and S
BR, BR and natural rubber, and SBR and natural rubber have only a few typical properties, and their effects are also remarkable. BR is prepared by solution polymerization using a conventional catalyst such as a Ziegler type catalyst or an organic alkali metal catalyst, for example.
Vinyl bond amount is 0-98%, trans 1.4 bond amount is 0
~95%. Also, as SBR,
For example, examples include those prepared from K by ordinary emulsion polymerization or solution polymerization, with a styrene bond content of 5 to 40% by weight and a vinyl bond content of the butadiene moiety of 0 to 98%.

Caden black used in the present invention is not particularly limited, but preferably has an average particle size of 10 mμ to 500 mμ, and its common abbreviation is EPC1MPC.

Channel programs such as RPC, CC, etc., SAF, l
5AF.

HAF, MAF, FEF, HMF, SRF, SPF
, GPF, APF.

It is appropriately selected from Tournespla such as F'F1CF, Ri, FT, Samarutura, Ri such as Fu, and Acetylene Pla, Ri, etc. The amount of carbon black to be used is usually selected from the range of 10 to 150 parts by weight, preferably 20 to 120 parts by weight, per 100 parts by weight of the total amount of rubber, depending on the purpose.

The rubber composition of the present invention may contain vulcanizing agents, vulcanization accelerators, vulcanization aids, softeners, tackifiers, fillers, reinforcing agents other than carbon black, anti-aging agents, etc., as desired. It can contain conventional rubber compounding agents.

Typical vulcanizing agents include sulfur and sulfur donors such as thiuram and thiazole, but there are also other vulcanizing agents. -Oxides, polyamines, metal oxides, urethane vulcanizing agents, resin vulcanizing agents, etc. can also be used as desired.

Vulcanization accelerators include sul7enamides, thiurams, thiazoles, guanidines, mercagtotriazones, and aldehyde-amines, and vulcanization aids include carmenic acids such as stearic acid and oleic acid. Metal compounds such as , zinc stearate, zinc oxide, i-gnesium oxide, calcium hydroxide, and lead carbonate are used as softening agents.
/'? ? Process oils such as finic, naphthenic, and aromatic are used; tackifiers include rosin, petroleum hydrocarbon resins, coumaron resins, and phenol-terpene resins; fillers include calcium carbonate, Klee, Merck, etc. are car? Examples of reinforcing agents other than black include silicic acid and its salts, and examples of anti-aging agents include amines and phenols. Incidentally, the above-mentioned vulcanization accelerator and vulcanization aid are mainly used in the case of vulcanization using sulfur or a sulfur donor.

The method of mixing the components constituting the rubber composition of the present invention is not particularly limited, and various rubber kneading machines are usually used. It can also be mixed with rubber in a process or a modification process to produce Karn Master Patch and Oil Master Patch, respectively. Further, other diene rubbers may be allowed to coexist during IR modification.

(Effect of the invention) Among the rubber compositions of the present invention, especially modified lR75 to 100
BR and/or styrene bond amount of 15 to 35 weight percent and vinyl bond amount of butadiene moiety of O to 5% by weight and 5BR of 25 to O weight percent of 0 to 5% by weight, or Average particle size '1 per 100 parts by weight of rubber mixture
Furnace carden bra for rubber of 0 to 50 mμ, Ri45
A composition containing up to 70 parts by weight has a high rebound modulus, high tensile stress, and excellent flex cracking resistance, and is suitable for large-sized truck, road, and pass tire treads.

In addition, the modified IR is 5-35% by weight and the amount of styrene bond is 15-35% by weight.
At 35% by weight, the amount of vinyl bonds in the butadiene moiety is O~50
A composition in which 45 to 70 parts by weight of furnace carden plastic for Dem with an average particle size of 10 to 50 mμ is blended with 100 parts by weight of a rubber mixture containing 95 to 65% by weight of SBR of H has a high rebound modulus and tensile stress, It has excellent flex cracking resistance and is suitable for tire treads for passenger cars.

Also, modified lR 35-65% by weight and vinyl bond amount 0-50%.
%BR and/or styrene bond amount is 15-35% by weight
SBR with a vinyl bond amount of 0 to 50% in the butadiene moiety.
100 parts by weight of a rubber mixture with 65-35% by weight of a furnace car for fm with an average particle size of 25-70 mμ? A composition containing 40 to 50 parts by weight of black has a high rebound modulus, high tensile stress, excellent flex crack resistance, and is suitable for tire side falls.

In addition, the modified IR is 40-100% by weight and the amount of vinyl bond is 0-100% by weight.
50% BR and/or S with a styrene bond amount of 15 to 35% by weight and a vinyl bond amount of the butadiene moiety of θ to 50%
BR60-0% by weight and better rubber or rubber mixture 10
- Furnace car for rubber with an average particle size of 40 to 90 mμ in 0 parts by weight is used as an embla.

The composition containing 40 to 50 parts by weight of
It has high tensile stress, rebound modulus, and tear strength, and is suitable for tire carcass and the like.

In addition, modified lR80-100% by weight and vinyl bond amount 0-5
0% BR and/or SB with a styrene bond content of 15 to 35% by weight and a vinyl bond content of the butadiene moiety of 0 to 50%
R20~O wt% and better rubber or rubber mixture 100
By adding 70 to 100 parts by weight of a furnace cargo plastic for rubber having a diameter of 10 to 40 mμ, the product has high hardness and tensile stress, and is suitable for tire bead fillers, rim cushions, and the like.

Furthermore, BR and/or styrene having a modified IR of 75 to 25% by weight and a vinyl bond amount of 35 to 98%.

To 100 parts by weight of a rubber mixture with 25 to 75 weight % of 88R with a bonding amount of 5 to 35 weight tts and a vinyl bonding amount of the butadiene moiety of 30 to 85%, add furnace cargen plastic for rubber with an average particle size of 10 to 50 mμ. A composition containing 40 to 70 parts by weight has a high impact resilience and is suitable as a tread for a low fuel consumption tire.

The invention! In addition to the above, Group 5 acids are used in tire inner liners, belts, hoses, and anti-vibration combs.

It is also suitable for use in ordinary rubber products such as footwear and cloth.

(Example) Next, the present invention will be specifically explained using examples.

The method for analyzing the modified rubber, the method for preparing an unvulcanized compound of the modified rubber, and the method for testing their physical properties in each example are as follows. Moreover, the number of parts of the compounded components is based on weight.

[Amount of ester groups in rubber]

The infrared absorption spectrum of the modified rubber from which the remaining low molecular weight components have been purified and removed is jilt, 1720-1735 cIf.
Absorption by C=0 stretching vibration of 1″ ester and 166
The ester group introduced into the rubber was quantified from the ratio to the absorption due to the C=C stretching vibration of 0α-1.

[Carboxyl group t in Comb]

After purifying and removing the low-molecular components in the rubber, it was measured by neutralization titration.

[Amount of Dull] Place about 0.2 g of rubber sample as strips inside a basket of about 31 squares made of 80 mm wire mesh, and add 2 g of rubber sample to toluene.
After soaking for 4 hours, the amount of dullness (a) was determined from the dry weight of the rubber remaining inside the basket. It is said that when the amount of dull is 2 or less, there is no substantial gluing.

[Preparation of unvulcanized rubber compound]

The modified comb was cross-mixed in a small Banbury mixer with various ingredients other than sulfur and vulcanization accelerator in the formulation shown in the example, and sulfur and vulcanization accelerator were added to the resulting mixture on a small roll. , and kneaded to prepare an unvulcanized mixture.

[Wallace plasticity]

Measurements were made on rubber or unvulcanized rubber compounds at 100° C. using a Wallace Ravid Blastmeter.

[Green strength]

The unvulcanized rubber compound was press-molded at 100°C for 5 minutes to form an unvulcanized rubber sheet with a thickness of 2 nm, and a dumbbell-shaped JIS No.
It is shown as the value of tensile stress at an elongation of 500 inches when a tensile test is conducted at a tensile speed of n.

[Vulcanization speed]

Oscillating disc rheometer at 145℃
Alternatively, it is expressed as the time (T, 5) until the torque measured at 150° C. reaches the maximum torque of 951.

[Tensile test]

The unvulcanized mixture was press-cured at 145°C or 150°C for a predetermined time to form a 2cm thick sheet, and a dumbbell-shaped No. 3 test piece specified in JIS-6301 was punched out.
The tensile speed was 41 nm.

[Tear strength]

From 2 cabinet thick vulcanized sheet, width 1511I11 length 100
The tanzakuya test piece of ■ was punched out, and 6 incisions were made perpendicularly to the side edge with a safety razor blade in the center of one side edge in the length direction, and the test piece was tensile at 500 gin and 41 m at 25°C. The average value of six samples, three in the grain direction and three in the direction perpendicular to the grain, is shown.

[Repulsion elasticity]

23℃ according to the test method described in JI13 6301
Measured at

〔hardness〕

Measurement was performed at 23° C. according to the spring type hardness test (C type) described in JIS K6301.

[W groove bending fatigue]

W, Ksrn: Kautschuek
and GtlmmL 8 1 9 5 (1955
), the number of bends required for the total length of the crack to grow to 12.5 cm was measured.

[Pico wear]

It was measured using a Guttori-Chi type Pico abrasion tester in accordance with ASTM D-2228.

[Sea urchin, toss skid resistance]

ASTM E-303-74 road surface (
Measurement was carried out using a 3M outdoor type B black safety quark).

Example I IR (98% of cis 1.4 bonds) 16ON was dissolved in 4112) dehydrated n-hexane, and the amount of glyoxyl listed in Table 1 was dissolved in a sealed glass container (separable flask) at 25°C under a nitrogen atmosphere. After adding 5 nCt4 of acid ethyl chloride and reacting for 60 minutes, 10,017 ml of methyl alcohol was poured in (it is assumed that this K addition reaction had stopped).

Thereafter, the reaction solution was poured into 4 volumes of acetone to completely solidify the mixture, and the solidified material was washed as small pieces.

Next, the coagulated pieces were immersed in acetone 31 containing an anti-aging agent (2,6-di-tert-butyl-4-methylphenol) of about -21i, washed, and then dried in a vacuum dryer overnight. By this, sample B shown in Table 1
, C, D, and E were obtained.

It can be seen that the sample of the present invention, I, was modified (introduction of ester groups) with almost no dulling or molecular weight reduction (change in Fores plasticity).

Table 1 * All operations other than the addition of ethyl glyoxylate and 8nCJ4 were performed under the same conditions as the others.

Next, the physical properties of the unvulcanized compounds and vulcanized products of the samples shown in Table 1 were measured. The results are shown in Table 2, and the formulation is as follows.

Compounded prescription rubber
1oo (parts) le σ car is 7 (Gitos 3 manufactured by Tokai Carbon Co., Ltd.) 50 aromatic oil
Zinc pentoxide 5 Stearic acid Disulfur
2.5 Table 2 It can be seen from Table 2 that the samples of the present invention, E and E, are particularly excellent in green strength and tear strength.

Example 2 The same I R160,9 used in Example 1 was dissolved in 31I dehydrated toluene, and the amount of glyoxylic acid listed in Table 3 was dissolved in a closed glass container (seven-parameter flask) at 25°C under a nitrogen atmosphere. After adding tert-butyl and S-ct4 and reacting for 30 minutes, 5 t) L/m of methyl alcohol was poured in (it is assumed that the addition reaction had stopped).Then, the reaction solution was The rubber was poured into methyl alcohol to completely coagulate the rubber, and the coagulated material was washed in small pieces. This is followed by about 21 anti-aging agents (2,6
- ditertiary-butyl-4-methylphenol) by soaking the coagulated pieces in 3 ml of methyl alcohol, washing them, and then drying them in a vacuum dryer overnight.
Sample F e G was obtained.

Table 3 Sample F, with GJC, unvulcanized compound (
The formulation was the same as in Example 1) and the physical properties of the vulcanizate were measured. The results are shown in Table 4.

Table 4 Example 3 The same lR160II as used in Example 1 was dissolved in 31 dehydrated benzene, and the amount listed in Table 5 was dissolved in a sealed gas container (separable flask) at 25°C in a hydrogen atmosphere. adding tert-butyl glyoxylate and BaCl2;
After reacting for 30 minutes, 100 - of methyl alulur was poured into the mixture (it is assumed that this stopped the addition reaction). Next, the amount of aCt aqueous solution listed in Table 5 was added.
Stirring was continued for 1 hour.

Thereafter, the reaction solution was poured into 3 ml of methyl alcohol to completely coagulate the rubber, and the coagulated material was washed as fine pieces. After soaking the coagulated pieces in 3 parts of methyl alcohol containing (methylphenol) and washing,
Sample H1I shown in Table 5 was obtained by drying in a vacuum dryer all day and night.

Table 5 Next, for Samples H and I shown in Table 5, the physical properties of the unvulcanized compound (the compounding recipe was the same as in Example 1) and the vulcanized product were measured. The results are shown in Table 6.

Table 6 It can be seen that the green strength is further improved compared to the invention example shown in Table 4.

Example 4 Benzyl glyoxylate was added as a glyoxylic acid ester, and BP and 0(C2H5)2 (ether complex of BF3) as Lewis acids were added in the amounts listed in Table 7, and a modification reaction was carried out. The operating method was the same as in Example 3 except that the HC1 aqueous solution was not added. As a result, Sample J shown in Table 8 was obtained.

Table 7 Next, the physical properties of the unvulcanized compound (the compounding recipe is the same as in Example 1) and the vulcanized product of Sample J were measured. The results are shown in Table 8. Table 8 Example 5 2 kg of synthetic IR (98 cis-1,4 bonds) was dissolved in 40 kg of dehydrated toluene and heated at 25°C under a nitrogen atmosphere in a stainless steel sealed container. While stirring, 18.8 J' of tert-butyl glyoxylate was added. Next, 38.
0# 5nCt4 was diluted with 40 times the volume of dehydrated benzene and gradually added dropwise, and after continuing stirring for another 30 minutes, 1.2
5 liters of methyl alcohol was poured in (it is presumed that this stopped the addition and reaction). Then HC of 106I
2 aqueous solution (10 g) was added and stirring continued for 1 hour. The obtained reaction solution was poured into 1001 methyl alcohol,
The rubber was completely coagulated and the coagulum was washed in pieces. This is followed by about 20.9% anti-aging agent (2,6-di-
The rubber coagulate strips were dipped in methyl alcohol 101 containing tertiary-butyl-4-methylphenol (tert-butyl-4-methylphenol) in several portions, washed, and dried overnight in a vacuum dryer to obtain the modifications shown in Table 9. IR samples were obtained □ Table 9 Next, using this modified IR, a composition having the following formulation, which is an example of a formulation suitable for a tire carcass, was prepared, and the physical properties of this composition were evaluated. The results are shown in Table 10.

Rubber (see Table 10) 100 (parts) Zinc oxide 3 Aromatic oil
5GPF (Geest v manufactured by Tokai Cargan Co., Ltd.) 45 Stearic acid.
2 sulfur
3N-cyclohexyl-
2-benzothiazylsul7enamide 0.8 (vulcanization accelerator) 2. Polymer of 2.4-trimethyl-1,2-dihydroquinoline 1 Table 10, the modified IR compositions are the corresponding comparative examples It can be seen that the green strength, 300% tensile stress and tear strength are higher than that of the composition of Example 6.A rubber composition prepared according to the formulation shown in Table 11 (the rubber is the same as that used in Example 5). ) was evaluated for physical properties. The results are shown in Table 11.

Experiment No. 1, 2, 3, 4, 5, 9, 10, 11. 12 and 13 is an example of a compound suitable for the tire tread of Haoya Truck Pass.
．． 10, 11, 12, 13) has a high tensile stress 2 rebound modulus, a long W groove bending fatigue life, and a comparative example (experiment number 1.
2, 3, and 4.5).

Run numbers 6, 7.14 and 15 are examples of formulations suitable for tire sidewalls. Among these, the examples of the present invention (experiment numbers 14 and 15) have a high tensile stress 2 rebound modulus of <, we
It can be seen that the bending fatigue life is long and superior to the comparative examples (experiment numbers 6 and 7).

Run numbers 8 and 16 are examples of formulations suitable for passenger car tire treads. Among them, the present invention example (experiment number 16)
The comparative example (
It can be seen that this is superior to Experiment No. 8).

Example 7 A rubber composition prepared according to the formulation shown in Table 12 (the rubber was the same as that used in Example 5) was evaluated for its physical properties.Table 12 shows the results.

All of these are examples of formulations suitable for tire bead fillers. It can be seen that the composition of the present invention has high tensile stress and hardness and is superior to the comparative example.

Table 12 Example 8 Rubber compositions prepared according to the formulations shown in Table 13 (where 9mm is the same as that used in Example 5) were evaluated for their physical properties. The results are shown in Table 13.0 All are examples of formulations suitable for treads of low fuel consumption tires, etc., but it can be seen that the composition of the present invention has a high impact resilience and is superior to the comparative example.

Table 13 5) Vinyl bond amount 70

Claims (1)

[Claims] Modified polyisoprene rubbers 5 to 10 obtained by reacting polyisoprene rubber with glyoxylic acid ester in the presence of a Lewis acid, or obtained by hydrolyzing this reaction
1. A rubber composition comprising 10 to 150 parts by weight of carbon black per 100 parts by weight of a rubber or rubber mixture consisting of 0% by weight and 95 to 0% by weight of another diene rubber.