JPS58154711A - Styrene/conjugated diene rubber - Google Patents

Abstract

PURPOSE:To titled rubber having a specified composition distribution width of reacted styrene, having excellent abrasion resistance, and skid wet resistance and low rolling resistance and suited for use in tires, etc., prepared by polymerizing styrene with a conjugated diene by a specified polymerization process. CONSTITUTION:The purpose styrene/conjugated diene rubber is prepared by emulsion-polymerizing 15-50wt% styrene with a conjugated diene (e.g., 1,3- butadiene, isoprene) in the presence of a radical initiator while adding the styrene monomer in portions in the course of the polymerization. The produced styrene/conjugated diene rubber has a composition distribution width of reacted styrene in the polymer of above 10%, a peak temperature width of a glass transition point as measured by a differential colorimeter of above 13 deg.C and a Mooney viscosity (ML1+4, 100 deg.C) in the range of 20-150 and has the three properties necessary for tires, i.e., abrasion resistance, wed skid resistance and low rolling resistance.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a novel styrene-conjugated diengo. * Concerning a new rubber suitable for tire treads.

Go▲Tojitesha is a manufacturer of automobile tire treads.

It is considered ideal to have good wear resistance for durability, wet skid resistance for driving safety, and low rolling resistance, which is a parameter for fuel efficiency.

However, each of the physical properties of the first element is said to be in an antinomic relationship with each other, and existing rubber materials
Simultaneous improvement was thought to be impossible.

The present inventors have conducted basic research on styrene-conjugated diengo▲ for many years, and as a result, for example, even if the same type of sterene-conjugated diengo▲ (hereinafter referred to as r B B RJ) is used, the reaction composition distribution of styrene differs. The physical properties of the rubber vary greatly depending on the type of rubber, and some types of styrene-conjugated dienego
Surprisingly, it was discovered that other knee properties were improved at the same time without sacrificing rolling resistance, and that the new rubber exhibited behavior completely different from conventional rubbers of this type. to the completion of.

In other words, the main feature of the present invention is a polymer consisting of styrene-conjugated diene, in which the reaction composition distribution width of styrene is 10.
The present invention is directed to a styrene-conjugated diene rubber which is characterized in that the peak temperature width of the glass transition point measured by a differential calorimeter is 11C or more.

The present invention will be explained in detail below.

As the conjugated diene component of the styrene-conjugated diene polymer of the present invention, for example, butadiene, isoprene, etc. can be used, but putadiene is usually used.

A feature of the polymer of the present invention is the reaction composition distribution of styrene defined by the peak temperature width of the glass transition point measured by the reaction composition distribution width pot differential calorific value needle.

First, the reaction composition distribution ll5K of styrene will be explained, which is a table concept as follows.

In other words, in a polymer formed by two or more types of polymers, the reaction composition of the monomers constituting each polymer molecule is generally different and not constant; It is a collection of various molecules that can be used to Such a composition distribution is called a reaction composition distribution, and the width of the distribution is called a reaction composition distribution width.

The polymer of the present invention has a reaction composition distribution width of 1091 or more when measured according to the following method,
It is preferably /r- or more.

(11 A polymer sample is extracted with a toluene-ethanol mixed solvent, and the emulsifier in the polymer sample is removed by isotube extraction.

(2) Approximately 0.11 l of the extracted polymer is accurately weighed and dissolved in tetrahydrofuran/00 Co.

(3) A suitable amount of polymer was precipitated by adding 9 ml of methanol to the obtained photosolution, and then treated in a centrifuge at 10,00 Or, p, m for 30 minutes,
Separate the precipitated polymer.

(4) When coco-methanol is further added to the solution from which the polymer has been separated, the polymer is precipitated from K and separated in the same manner as above.

By such methanol titration, the total amount of methanol added to the polymer fractionation operation tube was 1 liter.

oOK Repeat in Hikoru moat.

(5) Weigh the weight of the polymer sample separated in each operation,
The amount of bound methylene is determined by refractive index measurement or thermal separation gas chromatography measurement, and from this result, a reaction composition distribution curve for styrene is created, and from this, the width of the reaction composition distribution for styrene is determined.

FIG. 1 shows the reaction composition distribution of styrene determined according to the above method for 8BH described in Examples and Comparative Examples described later.

The horizontal axis shows the amount of reacted styrene (weight 9I) t, the vertical axis shows the cumulative percentage (-), and Δ'B in the figure shows the methylene O reaction composition distribution width.

In the present invention, the reaction composition distribution width of styrene is determined as described above, and a polymer with this value lower than tO% is not expected to sufficiently improve the ETS skid resistance.

Next, the peak temperature width of the glass transition point determined by the differential calorimeter (neo) ml will be explained. #Peak temperature width is
In DIlO@, it is the temperature range in the so-called transition region from the first inflection point of the endothermic peak caused by the glass transition to the final inflection point where it ends. Figure 1 shows the n of 8BR obtained in Examples and Comparative Examples described later.
s.

Measurement chart 1'! Toya what I stopped and showed.

The horizontal axis shows the temperature (C), and the vertical axis shows the amount of heat absorbed.12 In the figure, Δ
D indicates the peak temperature width of the glass transition point.

The peak temperature width (Δte) generally increases as the reaction composition distribution width of styrene becomes wider <t, b.

4 different depending on the shape of the reaction composition distribution of styrene.

In addition to cases where it can only be identified as a single beater, the reaction composition distribution is further polarized between low styrene content polymer molecules and high styrene content polymer molecules and exhibits multiple glass transition points. It becomes like this.

The polymer of the present invention has a peak temperature width of one or more glass transition points of /If or more, preferably 10
It is necessary for e1 to be 0 or more, and with respect to the measurement result of D80, the preferred amount of the polymer according to the present invention gives a glass transition point of 2 or more.

That is, the NGO chart of 411R obtained in Example I, which will be described later, is indicated by (&) in FIG.
()I).

Styrene, a typical methylene-conjugated diene rubber
Butadiene rubber is a general Kti, a required amount of styrene and butadiene monomer with a predetermined amount of water during the polymerization reaction! −
After charging and dispersing and emulsifying, the polymerization was started by adding the starting polymer, and when the reaction rate reached about 40, the reaction was stopped. The styrene reaction composition distribution width of the polymer thus obtained is about J-, and the peak temperature width of the glass transition point is 7C. This is a value close to the reactivity ratio Fi/ of styrene and butadiene,
Therefore.

It can be understood from the fact that these monomer polymerizations are close to ideal copolymerizations, and therefore the reaction composition distribution of styrene in the polymer is narrow.

As mentioned above, the novel styrene-conjugated diene rubber of the present invention has a reaction composition distribution width of stere/ of more than a specific value and l1l
OIIj! However, the beater temperature range is greater than a specific value of the glass transition point.

This makes it possible for the first time to create a rubber with improved wet skit resistance and abrasion resistance in a well-balanced manner without sacrificing rolling resistance.

Moreover, in the polymer of the present invention, the average amount of bound styrene is l! ~! Q weight-1 is preferably between /l and 30 weight, which is /! If the weight is too low, the wet squeezing resistance will not be sufficiently improved, and conversely, if the weight exceeds 10 weight, the rolling resistance will be large and the rubber-like elasticity will decrease. More Kf. Mooney viscosity (ML1+4.1oo
C) is 10~/jO,tFft or! considering dynamic properties such as tensile properties 1 heat generation and workability. 0~/J0
It is recommended that the range be within the range of .

Therefore, the styrene-conjugated diene rubber of the present invention can be produced by, for example, emulsion polymerization using a radical initiator, as shown in the examples below. Production is slow because it is produced by adding it in portions during polymerization.

In the case of the styrene-conjugated diene rubber of the present invention produced by the emulsion polymerization method as described above.

- According to an electron microscope with a magnification of 1,000 times, the presence of vertical domains was recognized, but the domain interfaces were not clear.

A characteristic state is observed in which the domain interface Z is also extremely small, at most /s.

The styrene-butadiene rubber obtained according to the present invention is compatible with other rubbers, such as high cis-polybutadiene.

It can be used by blending with natural rubber, polyisoprene, etc. Fillers such as carbon black or process oil, or sulfur.

It is used in combination with vulcanization accelerators, zinc white, etc.

The vulcanized rubber composition obtained by the present invention has excellent wet skid resistance and excellent abrasion resistance, and is therefore particularly suitable as a rubber for tire treads. The present invention will be described below with reference to examples, but the present invention goes beyond the gist of the present invention. The invention is not limited to this one embodiment.

In addition, "parts" in the following examples and ratio examples indicate parts by weight.

Example I According to the basic polymerization recipe shown in Table-1, the capacity was 100.
Into a polymerization reactor of 68%/0.0% t-dodecyl mercaptan, J-butadiene and a molecular weight regulator were added. / 9
1 part was added and emulsion polymerization was started under conditions of temperature IOC. When the reaction rate reached -, 1 part of styrene was added to continue the reaction, and when the total reaction rate reached 10, 0.0 part of styrene was added. The reaction was stopped by the addition of diethylhydroxyluacone.

Next, after recovering unreacted monomers according to a conventional method,
Highly aromatic polypropylene oil-part Q is emulsified and added, and the mixture is further co-coagulated to form a crumb, which is then dehydrated and dried to obtain oil-extended oil-11.

The reaction composition distribution width of styrene was measured for the obtained oil-extended #1R9lC, and the results are shown in Table 90 III.
The determination was carried out according to the method described in the main text of the specification, and the reaction composition distribution of styrene is shown as (&) in FIG.

In addition, according to the formulation shown in Table 1 of the oil-extended 81R1, MliL was added to Banbury-based kina, followed by /%IC1IO.
A vulcanized rubber compound (1) was obtained by vulcanization treatment for a minute. The peak temperature of the glass transition point of the wrinkled vulcanized rubber compound was determined by DIlO@determination, and the results are shown in Table-gXK. 1110 Char F is shown in FIG. The measurement conditions are as follows.

Equipment: PerkinElmer D80-1 Sensitivity: JN16 &l/sec Heating rate
: -0 portions 7 minutes Chart speed: Bait 0 ■/min Cooling hand IR: Use of liquid nitrogen Additionally, the above oil-extended six was treated with Banbury chlorine and 4 inch nitrogen according to the formulation shown in Table J. , then /bait IC, vulcanization for 40 minutes.

A vulcanized rubber compound (2) was obtained by processing. The rubber physical properties of the vulcanized rubber compound were measured and the results are shown in Table-! Shown below.

Example code According to the basic polymerization recipe shown in Table-1.

In the polymerization reaction S, 7 parts of /,! butadiene and 2
．． 1 part styrene and 0. / * 7 parts of a molecular weight regulator was added, and emulsion polymerization was started at a temperature of 10C. When the reaction rate reached 1/11, core and 7 parts of styrene were added to the polymerization reactor to continue the reaction t*, and added to the polymerization system, and when the reaction rate of 9 total 7 polymers reached 101Kfk, polymerization was started. Stop it, from now on.

An oil-extended aB formula was obtained in the same manner as in Example 1.

The styrene reaction composition distribution width of the obtained oil-extended BB'RK was measured in the same manner as in Example 1, and the results are shown in Table 1.

In addition, vulcanized rubber compounds (1) and (2) similar to those in Example 1 were obtained using 1 ml of the above oil-extended oil, and these were as follows:
The peak temperature of each positive transition point @ Comparative Example 1 Polymerization reaction 11 by adding 7 parts of /, J-butadiene and the knob part of styrene and the σ, l part of t-dodecyl mercaptan. Start.

Oil-extended flNRt was obtained according to the method.

Regarding the obtained oil-extended tlBRpc, the styrene reaction composition distribution width was measured in the same manner as in Example 1.

The results are shown in the table below, and the reaction composition distribution line is shown as the first line.
It is shown as Figure K (1)).

First, the same vulcanized rubber compounds (1) and (2) as in Example 1 were obtained using the oil-extended 8B trap, and the peak temperature width of the glass transition point and the rubber physical properties of these were measured in Example 1. Measured under the same conditions as I, and each result is Table-Quality, Table-! and shown in Figure 1.

Comparative Example According to the basic polymerization recipe shown in Table 1, 411 parts of J-butadiene and 0 and 4 parts of T were added to the polymerization reactor.
- Adding dodecyl mercaptan.

The reaction was started at a temperature of ioC. The reaction rate is /? %
When the reaction rate of all monomers reached to@yc, 0.01 part of diethylhydroxyl was added to continue the reaction. It was stopped. Thereafter, oil-extended BBB was obtained according to the method in Example.

The reaction composition distribution of styrene was measured in the same manner as in Example 1 for the nine oil-extended tlNRpc obtained, and similar vulcanized rubber compounds fi) and (2) were obtained, and the peak temperature of the j-las transition point was determined for each of these. The width and rubber physical properties were measured under the same conditions as in Example I, and the results are shown in Tables 1 and ! and shown in Figure J.

Table-1 (Part) Table-1
(Part) (11) i-7-1m Nyl-N'-4 Sobrovir paraphenylenedia ■) Table-J (Part) (1)) l-
tPururubenzotheazole sulfenide (2) Diablack 177de (3) Mu8〒MD4KOJ-7/Mu method (gutudrich flexometer) K compliant (4) Portapull wet skid tester used road surface: Sumitomo 3M Company Type B, Water Temperature -〇〇Tables -1 and -! As is clear from the above, the new rubber of the present invention, which has a styrene reaction composition distribution width of a specific value or more and a peak temperature width of a glass transition point measured by D80 of a specific value or more, has heat generation properties and rebound properties that are correlated with rolling resistance. Wet skid resistance and abrasion resistance are improved at the same time without sacrificing elasticity.

[Brief explanation of drawings]

Figure 1 shows the reaction composition distribution line of 8[t] styrene fractionated by methanol titration method, where the horizontal axis is the amount of reacted styrene (weight) tl-1 and the vertical axis is the cumulative percentage (li).
ΔB in Figure 1 represents the reaction composition distribution of styrene. Note that (color) is the BBN obtained in Example/2 and (1)) is the BBN obtained in Comparative Example 1. Figure 1 shows the measurement chart of the differential calorific value needle (DIIO) of the first oil expansion obtained in Example 2 and Comparative Example, with ★ marked, and the horizontal axis shows temperature change (C). The vertical axis represents the amount of heat absorbed, and Δte in Figure 1 represents the peak temperature width of the glass transition point. Note that (1) is Example/, tb) is Okako, and (Q) #i comparative example i 141 is the same and Toku9 oil dust BBR. Source: Mitsubishi Chemical Industries, Ltd. Kinsha Representative: Patent attorney: Mr. Hase 1 Figure: Reactive styrene 1 (z)

Claims (4)

[Claims] (1) A polymer consisting of styrene and a conjugated diene,
A styrene-conjugated diene rubber, characterized in that the reaction composition distribution width of styrene in the polymer is 10 or more, and the peak temperature width of the glass transition point measured by a differential calorimeter is tXC or more. (2) The conjugated diene is /,! The styrene-conjugated diene rubber according to claim 1, which is -butadiene. (3) Claim 1, characterized in that the average amount of bound styrene in the polymer is within the range of 1 to 6.
or the suderene-conjugated diene rubber described in item 1. (4) Mooney viscosity of polymer (ML144・1ooC'
) is Jθ~l! Styrene-conjugated diengo▲ described in Patent No. 1, characterized in that σ is within the range.