JPH0422927B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a composition containing an elastomeric copolymer having a novel structure, consisting of a conjugated diene and an aromatic vinyl compound, and a method for producing the same. More particularly, the present invention relates to compositions comprising styrene and butadiene, such as copolymers derived from styrene and 1,3-butadiene. These copolymers will be explained in particular detail below. The novel structure of the copolymers of the present invention can be defined by the distribution of styrene or other aromatic vinyl compounds in the copolymer molecules. for example,
When a molecule is grown continuously, the fraction of styrene in each increment of the molecule (differential styrene content,
styrene content) against total monomer conversion (expressed as a percentage of monomer reacted to form the copolymer), a curve showing the amount of styrene present in each increment along the length of the molecule is plotted. can get. For comparison, such a graph for a truly random copolymer with an average styrene content of 23% by weight, for example, would be a straight horizontal line. This indicates that the styrene content of successively increasing portions of the molecule is approximately 23% everywhere. The inventors have found that if a copolymer of a conjugated diene and an aromatic vinyl compound is used which has a significantly styrene-rich component or zone as shown in the accompanying drawings in the terminal portion of the copolymer molecule, the copolymer consists of a It has been discovered that the wet grip and/or rolling resistance properties of tires with tread can be significantly improved, leading to the completion of the present invention. The styrene-rich portion can be thought of as having two dimensions: length and height. That is, the length is its proportion of the total length or size of the copolymer molecule, and the height is the maximum differential styrene content in the terminal portion. In general, the more important feature is the maximum differential styrene content present in the terminal section, especially when the maximum value is in a narrow range that is much more limited than in a long range of the terminal section. Seem. Accordingly, a first object of the present invention is to provide an elastomeric copolymer composition of an aromatic vinyl compound and a conjugated diene suitable for use in the tread portion of a pneumatic tire. The copolymer has a vinyl content (as defined herein) of at least 30 wt%, and in the initiator portion of the copolymer molecule:
The differential aromatic vinyl compound content increases rapidly and significantly toward the outermost end of the terminal portion. A second object of the present invention is to provide an elastomeric copolymer composition suitable for use in the tread portion of a pneumatic tire, the differential styrene percentage content being less than 5% of the copolymer chain (monomer). (determined by the conversion rate) from the first value to the second value. The second value is at least 25% greater than the first value; the moiety is within 10% of the end of the copolymer chain (as determined by monomer conversion). Copolymers of particular interest are those in which the differential styrene percentage changes from a first value to a second value in an area (determined by monomer conversion) of 2.5% or less of the copolymer chain; 1; said zone is within 10% of the end of the copolymer chain (as determined by monomer conversion). For example, the 5% or 2.5% portion or such area may be the terminal portion of the copolymer chain. As is apparent from the accompanying drawings, the styrene tail in some of the copolymers of the present invention
is most pronounced in very small fractions (as determined by monomer conversion), such as 0.5%, 1.5% or 2%, of the copolymer chain. “Vinyl Content” as used throughout this document
The term refers to the weight proportion of 1,3-butadiene or isoprene in the copolymer polymerized in the 1, 2 or 3, 4 positions. When the diene is 1,3-butadiene, 1,2-polymerization produces pendant vinyl groups. When the diene is isoprene, the corresponding isopropyl group is produced by 3,4-polymerization. The aromatic vinyl compound may optionally include other monovinyl aromatic compounds, such as 1-vinylnaphthalene, 3,5-diethylstyrene, 4-n-propylstyrene, 2,4,-trimethylstyrene, 4
- phenylstyrene, 4-p-tristyrene,
3,5-diphenylstyrene, 3-ethyl-1-
Styrene mixed with vinylnaphthalene, 8-phenyl-1-vinylnaphthalene, etc. For example, if a branched or cross-linked structure is desired,
Polyfunctional vinyl compounds can also be used. For example, suitable polyfunctional vinyl compounds are divinyl compounds, such as divinylbenzene. Conjugated dienes are those which can be copolymerized with styrene in the 1 and 2 positions and which, when polymerized with styrene or other selected aromatic vinyl compounds or compounds, result in a copolymer with the desired elastic properties. It is something. For example, commonly used such dienes are 1,3-butadiene or isoprene. The styrene-butadiene copolymers of the present invention may, for example, contain at least 10% by weight of the copolymer.
(eg, 15, 20, 25, 30 or 40%). If polystyrene blocks are used to increase wet grip, the size of the blocks is preferably within the range of 20,000 to 40,000. Expressed as a percentage of the copolymer with a molecular weight of 300,000, it is 7 to
It is 13wt%. The copolymers of the present invention are produced by subjecting a mixture of an aromatic vinyl compound and a conjugated diene to solution polymerization conditions in the presence of an initiator, such that the proportion of the aromatic vinyl compound is increased or increased in the initiation stage of the copolymerization reaction. by means of a solution polymerization process comprising converting at least a portion of the living copolymer produced into a linear or branched copolymer by means of a polyfunctional coupling agent. be able to. For example, lithium hydrocarbon compounds are used as suitable initiators. Suitable monolithium initiators (leading to linear polymers) are, for example, methylthiium, ethyllithium, n-propyllithium, isopropyllithium, n-butyllithium, sec-butyllithium, t-butyllithium,
n-aminolithium, isoamyllithium, n-
These include hexyllithium, n-octyllithium, and phenyllithium. Suitable solvents (which may be binary or other multicomponent solvents) for use in this reaction include, for example, alkanes, alkenes, cycloalkanes and cycloalkenes, such as benzene, toluene, etc. , xylene, ethylbenzene, isobutane, n-pentane, isopentane, n-heptane, isooctane, n-decane, cyclopeptane, methylcyclopentane, dimethylcyclopentane, cyclohexane, methylcyclohexane,
These include dimethylcyclohexane, 1-butene, 2-butene, 1-pentene, 2-pentene, and cyclopentene. To increase the wet grip of the tire, it is preferred to use a structural modifier in the polymerization reaction. The use of structural modifiers increases the amount of butadiene polymerized at the 1 and 2 positions. Such polymerization results in the formation of vinyl groups (or corresponding groups when other conjugated dienes are used) that enhance the wet grip of tires with treads containing the polymer. occurs. Suitable modifiers include (1) ethers, thioethers, cyclic ethers,
t-amines, such as diethyl ether, dimethyl ether, tetrahydrofuran, dioxane, orthodimethoxybenzene, monoglyme, diglyme, triethylamine; (2) hexamethylphosphorotriamide; (3) difunctional Lewis bases, such as tetramethylethylenediamine (4) Organic potassium or sodium compounds, such as potassium t-butoxy. When structural modifiers such as those described above are used, 1,2-polymerization occurs in preference to 1,4-polymerization or other alpha-omega polymerizations. Furthermore, as the rate of copolymerization of styrene and butadiene increases, more random copolymerization occurs. For example, by appropriate selection of reaction conditions, copolymers can be produced with a butadiene content that approaches 100% conversion, or somewhat as close as possible to the butadiene content in the polymer at 100% conversion. With appropriate modifiers, usually no polystyrene blocks are formed at the ends of the molecule unless additional styrene is added. The solution polymerization in the presence of a copolymerization initiator of styrene and diene components according to the present invention is carried out such that (a) first, the aromatic vinyl compound/conjugated diene weight ratio is greater than the ratio contemplated for the resulting copolymer; (b) introducing into the reaction system a mixture of an aromatic vinyl compound and a conjugated diene, the ratio of which is equal to or less than the ratio contemplated for the resulting copolymer; (c) optionally further introducing into the reaction system only a conjugated diene or a mixture of an aromatic vinyl compound and a conjugated diene, the ratio of which is lower than the ratio intended for the resulting copolymer; and (d) converting at least a portion of the resulting living copolymer into a linear or branched copolymer with a multifunctional coupling agent, and optionally deactivating the living copolymer with a terminal capping agent. do. A suitable temperature for carrying out this reaction is, for example, 20
Within the range of ℃~70℃ or 80℃. Great care must be taken when using high temperatures to accelerate conversion rates. This is because high temperatures tend to cause 1,4-polymerization, and when 1,4-polymerization occurs, the vinyl content is reduced to below 30%. The copolymers of the present invention can be formed into composite molecules obtained by coupling together two or more small copolymer molecules. This coupling reaction can be easily carried out by using a coupling agent. Difunctional coupling agents such as dibromoethane lead to linearly linked copolymers, trifunctional or other multifunctional coupling agents such as silicon tetrachloride (SiCl ₄ ), diethyl adipate (DEAP),
Tetrafunctional compounds such as dimethyl adipate or stannic chloride (SnCl ₄ ) lead to nonlinear or branched copolymers. It must be noted that the styrene content shown in all the accompanying drawings is that of the unlinked copolymer. Coupling is usually preferably carried out so that the copolymer molecules are bonded together at one end of the molecule that does not have a tail. Coupling is usually carried out at the end of the copolymerization reaction. If the copolymer is such that it has a terminal tail, i.e. a styrene tail formed at the end of the styrene-butadiene copolymerization process, when it couples, the tail is no longer "free" and can be attached to other copolymer molecules. combine with If the coupling is only partially completed, such as when the coupling is completed to 50% of the theoretical amount, the products of the coupling reaction will consist of linked and unlinked copolymers. Therefore, when the products of such a coupling reaction are used in the tread portion of a tire, they provide, at least to some extent, a useful compromise between wet grip and rolling resistance. However, an increase in the degree of coupling at the end tail is detrimental to the balance between grip force and resistance. On the other hand, coupling copolymers with begin tails does not reduce the amount of free tails. As a result, the above-mentioned combination of grip force and resistance value is not compromised. Another method of producing branched polymers is to use initiators with three or more active functional groups. The polymerization reaction is carried out using an end-stopping agent (end-stopping agent).
agent). As end-stopping agents, for example water, alcohols or proton-releasing compounds such as amines can be used. The presence of a high proportion of styrene (as a mixture with butadiene) in the early stages of the reaction appears to be related to the superior properties exhibited by the product copolymers. In the description of the examples below, it will be understood that a literally complete conversion has taken place. This appears to be particularly important for terminating the reaction when high proportions of styrene are present. Test Example 1 (Production of copolymer) A stainless steel reactor with a capacity of 10 was charged with 2000 g of cyclohexane and 2000 g of isopentane. After that, 115g of styrene, 38.5g of butadiene
and 2.25 g of orthodimethoxybenzene. The temperature of the contents was 60°C. Impurities in the solvent/monomer blend that could react with sec-butyllithium were then deactivated by titration with a solution of sec-butyllithium in cyclohexane (concentration 100 mmol/l). After the temperature was observed to rise by 0.5 °C, sec-butyllithium solution (33.3 ml of 100 mmol/cyclohexane solution)
was added to initiate polymerization. An increase in temperature of 0.5° C. means that all impurities that could interfere with polymerization have been deactivated. Simultaneously with the addition of the polymerization initiator, the styrene/butadiene blend (styrene/butadiene polymerization ratio/
17.5/85.5) was charged into the reactor at a rate of 43.6 g/min. 60 by cooling the temperature of the reactor contents
It was maintained at ℃. Immediately after the monomer addition was complete, 192.5 g of butadiene was fed into the polymer solution at a rate of 2.00 g/min. After adding these monomers, the polymerization reaction was allowed to proceed for an additional 40 minutes, thus increasing the monomer conversion rate.
It was over 99.9%. Then 0.5g of methanol
was added to stop the polymerization reaction. Finally, 0.5 g of 2,6-di-t-butyl para-cresol was added as a stabilizer. The polymer was recovered from the polymerization solution by coagulating with steam. Test Example 2 A stainless steel reactor with a capacity of 10 was charged with 2000 g of cyclohexane and 2000 g of isopentane. After that, 115g of styrene, 38.5g of butadiene
and 2.25 g of orthodimethoxybenzene. The temperature of the contents was 60°C. Then, sec−
Impurities in the solvent/monomer blend that could react with butyllithium were deactivated by titration with a sec-butyllithium solution in cyclohexane (concentration 100 mmol/). After the temperature was observed to rise by 0.5 °C, the sec-butyllithium solution (66.6 mmol/100 mmol of cyclohexane solution)
ml) was added to initiate polymerization. Temperature is 0.5℃
An increase means that all impurities that could interfere with polymerization have been deactivated. Similar to the addition of a polymerization initiator, the styrene/butadiene blend (styrene/butadiene polymerization ratio:
17.5/82.5) were fed into the reactor at a rate of 81.7 g/min. By illustrating the temperature of the reactor contents 60℃
maintained. Immediately after the monomer addition was completed, 192.5 g of butadiene was pumped into the polymer solution at a rate of 1.9 g/min. After adding these monomers, the polymerization reaction was allowed to proceed for an additional 60 minutes, thus increasing the monomer conversion rate.
It was over 99.9%. After that, 0.33 g of diethyl adipate was added to couple the polymer chains, increasing the molecular weight by 4 times (coupling efficiency: approx.
50%) obtained a polymer with a branched structure. Next, 0.5 g of methanol was added to stop the polymerization reaction. Finally, 0.5 g of 2,6-di-t-butyl para-cresol was added as a stabilizer. The polymer was recovered from the polymerization solution by coagulating with steam. Test Example 3 A stainless steel reactor with a capacity of 10 was charged with 2000 g of cyclohexane and 2000 g of isopentane. After that, 115g of styrene and 28.5g of butadiene.
and 2.25 g of orthodimethoxybenzene. The temperature of the contents was 60°C. Then, sec−
Impurities in the solvent/monomer blend that could react with butyllithium were deactivated by titration with a sec-butyllithium solution in cyclohexane (concentration 100 mmol/). After the temperature was observed to rise by 0.5 °C, the sec-butyllithium solution (66.6 mmol/100 mmol of cyclohexane solution)
ml) was added to initiate polymerization. Temperature is 0.5℃
An increase means that all impurities that could interfere with polymerization have been deactivated. Simultaneously with the addition of the polymerization initiator, the styrene/butadiene blend (styrene/butadiene weight ratio:
17.5/82.5) were fed into the reactor at a rate of 81.7 g/min. 60 by cooling the temperature of the reactor contents
It was maintained at ℃. Immediately after completing the addition of monomers, add butadiene.
192.5 g was pumped into the polymer solution at a rate of 1.9 g/min. After adding these monomers, the polymerization reaction was allowed to proceed for an additional 40 minutes, thus increasing the monomer conversion rate.
It was over 99.9%. Then dibromoeta 0.66g
was added to couple the polymer chains to obtain a linear polymer whose molecular weight was doubled (coupling efficiency was about 50%). Next, 0.5 g of methanol was added to stop the polymerization reaction. Finally, 0.5 g of 2,6-di-t-butyl para-cresol was added as a stabilizer. The polymer was recovered from the polymerization solution by coagulating with steam. Each test example is accompanied by a graph plotting the differential percentage of styrene in the copolymer portion of the molecule against the total monomer conversion (corresponding to the percent molecular size of the copolymer molecule).
The styrene difference at various conversion rates was calculated from the copolymerization kinetics of styrene and butadiene using the following equation. S1/B1=S/B×R1S+B/R2B+S (1) where: S1=weight fraction of styrene moieties in the copolymer B1=weight fraction of butadiene moieties in the copolymer S=weight fraction of styrene moieties in the monomer blend Ratio B = weight fraction of butadiene moieties in the monomer blend R1 = reactivity ratio of styrene R2 = reactivity ratio of butadiene Weight fraction of styrene and butadiene moieties in the copolymer relative to weight fraction of styrene and butadiene moieties in the monomer blend The rates were determined by polymerizing styrene and butadiene feedstocks of various compositions to less than 5% conversion and infrared analysis of the styrene and butadiene content of the various copolymers produced. After determining this ratio, R1 and R2 are determined by Fineman
and Ross J. Polymer Science, 5 , (1950)
Calculated according to the method disclosed on page 259. For example, the polymerization conditions applied in the majority of the test examples mentioned above, i.e., polymerization carried out in a cyclohexane reaction solvent and at a temperature of 60°C using a modifier (ODMB) at a concentration of 450 ppm; R1 and R2 values of 0.73 and 1.40, respectively, were obtained for styrene and butadiene under the conditions. Therefore,
If a monomer feedstock of known composition is used as a starting material, the composition of the copolymer can be calculated at the beginning of the copolymerization reaction (conversion rate is almost 0 percent) by using equation (1). Then, as the polymerization time progresses further, i.e., when the softening rate increases, the composition of the polymer portion produced is determined by the formula (1 ) can be used for calculation. In the figure, the total monomer conversion rate is referred to as "monomer conversion rate" for convenience. The horizontal line in the figure indicates the average styrene content (%) of the polymer. Referring to Figure 1 of the accompanying drawings, the first endward portion of the molecule (herein referred to as the "begin tail")
There is a styrene-rich component in the tail),
The styrene content of the rear end portions is lower than the average styrene content of the polymer. The styrene content of the central portion is approximately the same as the average styrene content of the polymer. The differential styrene content of the copolymer of Test Example 1 ranges from the first value (threshold) (T) of 46% in the monomer conversion section between 0% and 5% conversion to the second value at 0% monomer conversion. Value (maximum value) (M)
It changes at 71%. In other words, the amount of variation (M-T) is 25%
It is. The differential styrene content in the 2.5% band at the end of the 5% portion is the first value (threshold value) (T').
It varies from 56% to a second value (maximum value) (M) of 71% at 0% monomer conversion. Therefore, the amount of variation (M-T') is 15%. The respective M, T, T', (M-T) and (M-
The values of T') are listed in Table B below. Table B
As is clearer, all values of (M-T) are 25
% or more, and all values of (M-T') are 14% or more. Figures 2 and 3 illustrate the polymers of Test Examples 2 and 3 produced by coupling polymers obtained in substantially the same manner as the Test Examples. Obviously, Figures 2 and 3
The graph in the figure is similar to the graph in FIG. Second
The illustrated polymer appears to be a branched polymer containing four polymer linear chains linked together. In contrast, the polymer shown in Figure 3 has two
It is thought to be a linear polymer consisting of linear polymer chains. As is clear from these figures, the specific percentages of "molecular length" mentioned above were derived from the corresponding values for monomer conversion, and all molecules of any polymer have the same length. should not be understood as such. As is clear from the attached drawing, the styrene differential is
It is a value converted to monomer conversion rate, which rapidly decreases from a high value corresponding to the length of the polymer molecule. For some polymers, this reduction value is particularly large in the first few percent (eg 1, 2 or 3%) of the length of the polymer. As is clear from Table A, the vinyl content (i.e.
The amount of butadiene component of the polymer polymerized in the 1st and 2nd positions) is in all cases greater than 30%, and the value is
In the range of 40% to 50%, especially 45% to 50%. The styrene content of each polymer is within the range of 20% to 30%.

【table】

TABLE The compositions of Examples 1-3 were tested to assess the wet grip and rolling resistance properties of the compositions on a road surface. All of these compositions were used as tread molding materials for model tires ranging in size from 5.7 to 20.3 centimeters. These model tires were subjected to the following two types of tests. On a wet Delugrip road surface (Delugrip is a trade name, details are given in British Patent No. 1393885), the grip force is
of the Institute of the Rubber Industry
“G.Less published in Vol.8, No.3 (June 1974)
and a variable speed internal drum machine (VSIDM) disclosed in the AR Williams paper. Wet grip force measurements were made on fixed wheel sliding friction. Rolling resistance is determined by Equations 3 and 1 below.Transaction of the Institute of Rubber Industry
Rotary power loss machine disclosed in Rubber Industry) 34 , No. 5 (October 1958)
machine). The results are shown in Table C below. Equation 3, 1 stated in Table C is: Rolling resistance = 8.75E″+0.83E″/(E*) ² +66
(3,1) where E″ and E″/(E*) ² have the following significance: E″ = loss modulus E in MPa ^* = multiple modulus E″ in MPa /(E ^* ) ² is expressed in GN/ ^m2 . This equation applies to Dunlop's SP4 steel radial tires.

Table C As is evident from Table C above, the tires tested have a very good compromise between wet grip and rolling resistance. Having a styrene-rich component at the end of the polymer molecule significantly improves wet grip, and having a high vinyl content and no styrene-rich component in the rest of the polymer molecule significantly improves rolling resistance. It seems likely that it will be done. The abbreviations used in the following description have the following meanings. S = Styrene B = Butadiene S/B = Mixture of styrene and butadiene SBR = Styrene-butadiene copolymer ODMB = o-dimethoxybenzene DEAP = Diethyl adipate DVB = Divinylbenzene S-BuLi = Secondary butyl lithium diglyme = Diethylene glycol dimethyl ether PS = Polystyrene MW = Molecular weight B = Branched molecule L = Linear molecule BC = Before coupling Unless otherwise stated, ratios and percentages stated in the test examples are by weight. Test Examples 4A and 4B Two branched styrene-butadiene copolymers were prepared using the components and conditions set forth in Table 1A below. The manufacturing method used was as follows. A stainless steel reactor with a capacity of 10 was charged with 4000 g of cyclohexane. Then Table 1A
The initial monomer batch charge and modifier shown in (1) were added. The temperature of the contents was 60°C. Then, a solvent/
Impurities in the monomer blend were removed using a cyclohexane solution of sec-butyllithium (concentration 100 mmol/
) was inactivated by titration. temperature
After a 0.5°C rise was observed, a sec-butylurium solution was added to initiate polymerization. temperature
An increase of 0.5°C means that all impurities that could interfere with polymerization have been deactivated. After 5 minutes, the first continuous monomer addition was made. The reactor contents were maintained at the stated temperature by cooling. Immediately after the first continuous monomer charge was completed, a second continuous monomer addition was made. Thereafter, polymerization was proceeded under the conditions shown in Table IA. Then the coupling agent (DEAP) listed in Table IA
was added to the reactor. The use of coupling agents produces partially coupled copolymer chains, resulting in branched copolymers, as shown in Table IB. Finally, 0.5 g of 2,6-di-t-butyl para-cresol was added as a stabilizer. The polymer was recovered from the polymerization solution by coagulating with steam. Test Example 5 Starting tail amount: 5% of total polymer Styrene/butadiene ratio: 90/10 Main chain amount: 95% of total polymer Styrene/butadiene ratio: 19.5/80.5 Total styrene content (IR analysis): 23.5% Capacity: 10 2340 g of cyclohexane, 49.5 g of styrene, and butadiene in a stainless steel reactor.
5.5 g and 2.6 g of ODMB were charged. The temperature of the reactor contents was brought to 50° C. by heating the reactor externally. Then a concentration of 100 mmol/
Polymerization of the monomers was initiated by adding 73.3 ml of S-BuLi cyclohexane solution. Within 30 minutes of starting the polymerization, virtually all monomers were converted to styrene-butadiene copolymer. After this, styrene in 2340g of cyclohexane
A blend of 200 g and 842 g of butadiene was added over 60 minutes. The temperature of the reactor contents was maintained at 50°C during this addition. After adding the monomers, the polymerization reaction was continued for an additional 60 min at 50 °C, followed by DEAP to couple the living linear polymer chains to produce a radial structured polymer.
0.30g of was added. Then 2,6 as a stabilizer
-Add 0.5g of di-t-butyl para-cresol,
The copolymer was then recovered from the polymerization solution by coagulating with steam and drying. The properties of the obtained polymer are shown in FIG. Test Example 6 Cyclohexane was added to the reactor used in Test Example 5.
2340 g, styrene 8.8 g, butadiene 13.2 g and ODMB 2.6 g were charged. Concentration 100 mmol/
The monomers were polymerized at 50° C. by adding 73.3 ml of S-BuLi cyclohexane solution.
After 30 minutes, 244 styrene in 2340 g of cyclohexane
847 g of butadiene was fed into the reactor over a period of 60 minutes. It was then processed in the same manner as described in Example 5. The properties of the obtained polymer are shown in FIG. Test Example 7 Cyclohexane 2340 was added to the reactor used in Test Example 5.
g, styrene 22g, butadiene 33g and
2.6g of ODMB was charged. Concentration 100 mmol/
Polymerization was initiated by adding 73.3 ml of S-BuLi cyclohexane solution. After 30 minutes, a formulation consisting of 244 g of styrene and 847 g of butadiene in 2340 g of cyclohexane was fed into the reactor over a period of 60 minutes. Thereafter, it was treated in the same manner as described in Test Example 5. The properties of the obtained polymer are shown in FIG. Total styrene content (IR analysis): 23.2% Data regarding the structure of the copolymers of Test Examples 5 to 7 are shown in Table B.

[Table] Polymerization data Solvent: cyclohexane 4000g; Final solid content: 20wt
%
Polymer weight: 1000g

TABLES Remarkable data regarding the structure of the copolymers obtained in each test example are shown in Tables B and B below. In the table, the value for Mooney year is ML1+4 100℃; the value for IR analysis is wt%; Q=w/n

[Front] Rim
4B WRC5802 ODMB B〓DEAP 183 432
278 1.55 63 47 17 36 24.8
47

【table】

[Table] By using the reaction kinetics of Test Example 4A and the following various methods, the differential styrene percentage (%) in the copolymer portion of the molecule can be calculated as monomer conversion (%) (molecular size of the polymer molecule ( %)
A graph plotted against (corresponding to) is obtained. Various values for the sizes of the various parts of the molecule and their styrene differences are obtained by reading the respective drawings (ie, graphs). For example, referring to FIG. 5 corresponding to Test Example 4B, the following will be understood. That is, the polymer of Test Example 4B can be considered to have a molecule composed of two types of parts. The first part, the main chain part, consists of about 5% of the molecule, in which the styrene content is reduced to one end of the molecule (i.e.
from 83% at the "starting" end to 29% at the end of the first section. The second portion, the phlegm portion, comprises the remaining 95% or so of the molecule. For each graph, the first value (threshold) (T) at one end of the portion of the graph corresponding to 5% monomer conversion and the second value (maximum) (M) within that 5% portion are It is shown with a mark. Figure 4,
In all other figures except Figures 5, 6, and 7, the 5% portion is 0% to 5% monomer conversion.
% range. In FIG. 4, the 5% portion ranges from 3% to 8% monomer conversion; in FIG. 5, the 5% portion ranges from 2.5% to 7.5% monomer conversion; in FIG. Conversion rate 0.5%~5.5
% range. In Figure 7, the monomer conversion rate
Injuries are shown in the 2.5% portion. In all other figures (i.e., graphs) other than FIG. 7, each 5% end of monomer conversion is bisected into two 2.5% bands of monomer conversion. Thus, the variation in styrene increments in these two zones is illustrated. In all examples (including Figure 7) the styrene content increases by more than 14%. It must be noted that each figure only shows the styrene increments of the copolymer. The polystyrene component is not shown in the figure. In Figure 4A, the horizontal line at 94% styrene content indicates the copolymer. As is clear from these figures, the specific percentages of "molecular length" mentioned above were derived from the corresponding values for monomer conversion, and all molecules of any polymer have the same length. should not be understood as such. As is clear from the table, the vinyl content (i.e. 1,
The amount of butadiene component of the polymer polymerized in the 2nd position) is in all cases more than 30%, and the vinyl content is mostly between 4% and 50%, especially between 45% and 50%.
is within the range of The styrene content of each polymer is 20
% to 30%, especially in the range of 25% to 30%. The copolymers of Examples 4A, 5, 6, and 7 were all dispensed into elastomeric compositions having the following composition in each example. Ingredient content (parts by weight) Copolymer 100 Sulfur 1.75 Accelerator - CBS (cyclohexylbenzthiazyl sulfenamide) 1 Carbon Black N375 50 Antioxidant BLE75 2 Zinc oxide 3 Stearic acid 1 This elastomer composition was heated for 15 minutes. Vulcanization was carried out at 140° C. for 60 minutes in a steam autoclave that reached the set temperature. These compositions were tested to assess their wet grip and rolling resistance properties on a road surface. All of these compositions were used as tread forming materials for model tires ranging in size from 5.7 to 20.3 centimeters. These model tires were subjected to the following two types of tests. The grip strength on wet Delugrip road surfaces (Delugrip is the product name) is ``Journal of
the Institute of the Rubber Industry”Vol.8,
Measurements were made using a variable speed internal drum machine (VSIDM) as disclosed in the article by G. Less and AR Williams, published in No. 3 (April 6, 1974). Wet grip force measurements were made on fixed wheel sliding friction. Rolling resistance was measured with a rotating power loss machine. The results obtained are shown in Table D below.

Calculated according to [Table].
As can be seen from Table D above, the tires tested had a very good compromise between wet grip and rolling resistance. Having a styrene-rich component at the starting end of the polymer molecule significantly improves wet grip, while the rest of the polymer molecule has a high vinyl content and no styrene-rich component, which significantly improves the resistance. It seems that this will be improved. Test Examples 8, 9 and 10 Several additional copolymers were prepared according to the conditions set forth in Table 17 below. These properties are shown in Table A below. Isoprene was used in tests 8 and 9. Isoprene was used in such a way that the isoprene was almost completely polymerized in the "tail" portion of the copolymer. This is an example of using a second conjugated diene hydrocarbon with butadiene. The copolymers of Test Examples 8 and 9 are begintail polymers, and the nature of the "tail" is determined primarily by the batch charge. In Test Example 8, the diene component in the batch charge is half butadiene and the other half isoprene, resulting in a "tail" with a high isoprene content. In Test Example 9, the batch-charged diene component is all isoprene, resulting in a "tail" containing almost no butadiene. In Test Example 10, as in Test Examples 8 and 9, monomer addition was carried out continuously after the reaction was initiated.

【table】

【table】

[Table] Test Examples 8 to 10 The tread portions of full-sized tires (155 SR13 SP4) were formed using the copolymers, and their wet grip strength and rolling resistance were measured as follows. Wet grip force: Measured at Karlsruhe University using an internal drum test device. Rolling resistance: Measured using the rotational power loss machine described above. The results obtained are shown in Table 19 below.

【table】

[Table] Calculated accordingly.

[Brief explanation of drawings]

FIGS. 1 to 10 are graphs showing the relationship between monomer conversion rate and styrene content.

Claims (1)

[Scope of Claims] 1. From a living copolymer of an aromatic vinyl compound and a conjugated diene and a linear or branched copolymer produced by converting at least a portion of the living copolymer with a polyfunctional coupling agent. an elastomeric copolymer composition, wherein the living copolymer is optionally deactivated with a terminal capper, the living copolymer having an average aromatic vinyl compound content of at least 10% by weight and a vinyl content of at least 30% by weight. and not more than 5% of the copolymer chain (as determined by monomer conversion)
, the percentage differential aromatic content changes from a first value to a second value, the second value being at least 25% greater than the first value; and the portion is 10% from the starting end of the copolymer chain. % (determined by monomer conversion)
A composition characterized by: 2. The composition according to claim 1, wherein the aromatic vinyl compound is styrene. 3. The composition according to claim 1 or 2, wherein the conjugated diene is butadiene or isoprene. 4. The composition of claim 1, wherein the copolymer is a styrene-butadiene copolymer. 5. The composition of claim 1, wherein the 5% portion is the starting end portion of a living copolymer chain. 6. The percentage differential aromatic vinyl compound content changes from a first value to a second value in a portion (determined by monomer conversion) of not more than 2 1/2% of the copolymer chain; is at least 14% greater than the first value; and this portion is within 10% of the starting end of the copolymer chain (as determined by monomer conversion). Compositions as described. 7. A composition according to claim 5 or 6, wherein the second value is at 0% monomer conversion. 8. A composition according to any of claims 1 to 7, wherein the vinyl content of the copolymer ranges from 30 to 60% by weight. 9. The composition according to any one of claims 1 to 8, wherein the copolymer is a linear compound. 10 Claim 1, in which the coupling is made by a tetrafunctional coupling agent
The composition according to any one of items 1 to 8. 11. An elastomeric copolymer composition in which a living copolymer of an aromatic vinyl compound and a conjugated diene is deactivated with a terminal capper,
the living copolymer has an average aromatic vinyl compound content of at least 10% by weight and a vinyl content of at least 30% by weight;
% (determined by monomer conversion), the percentage differential aromatic content changes from a first value to a second value, the second value being less than the first value.
and this portion is within 10% of the starting end of the copolymer chain (as determined by monomer conversion). A mixture of a group vinyl compound and a conjugated diene is prepared under solution polymerization conditions in the presence of an initiator using a means that allows the aromatic vinyl compound to rapidly increase toward the end in the initiation stage of the copolymerization reaction. and then converting at least a portion of the living copolymer formed into a linear or branched copolymer with a multifunctional coupling agent, and optionally deactivating the living copolymer with a terminal capping agent. How to characterize it. 12 The means performs 1,2-polymerization of a conjugated diene by 1,
12. A process according to claim 11, comprising the use of a structural modifier to give preference to 4- or other alpha-omega polymerization. 13. Claims 11 or 12, wherein said means comprises introducing an excess amount of the aromatic vinyl compound into the reaction zone prior to the initiation of the copolymerization reaction.
The method described in section. 14. The method according to claim 13, wherein the aromatic vinyl compound is introduced continuously. 15 (a) First, a mixture of an aromatic vinyl compound and a conjugated diene having a weight ratio of aromatic vinyl compound/conjugated diene that is higher than the ratio intended for the copolymer to be produced is introduced into the reaction system, (b) then, charging the reaction system with a mixture of an aromatic vinyl compound and a conjugated diene whose ratio is equal to or less than the ratio contemplated for the resulting copolymer; (c) optionally further containing only the conjugated diene or the ratio; (d) introducing into the reaction system a mixture of an aromatic vinyl compound and a conjugated diene in which the ratio is less than the ratio contemplated for the resulting living copolymer; 12. A process according to claim 11, comprising converting the living copolymer into a linear or branched copolymer and optionally deactivating the living copolymer by means of a terminal capper. 16. Claim 15, wherein step (c) comprises first charging a mixture of an aromatic vinyl compound and a conjugated diene, and then charging only the conjugated diene.
The method described in section. 17. The method according to any one of claims 11 to 16, wherein the terminal capping agent is water, alcohol, or amine.