JP2014196487A - Production method of modified polymer and diene polymer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a production method of a modified polymer in which an alkoxysilyl group can be easily introduced in a polymer main chain structure.SOLUTION: A system that includes: a polymer in which the polymer having a carbon-carbon double bond in a main chain is decomposed to lower a molecular weight by that the carbon-carbon double bond is subjected to oxidation cleavage; and a 3 functionality molecule that has an alkoxysilyl group represented by the following formula (A) in a structure is subjected to acidity basicity change so as to be basicity when being acidity and to be acidity when being basicity, thereby the decomposed polymer and the 3 functionality molecule are coupled to obtain a modified polymer in which the alkoxysilyl group is introduced. In the formula (A), R, Rand Reach denote an aldehyde group or a carbonyl group, and Rdenotes an alkyl group with a carbon number of 1-10.

Description

  The present invention relates to a method for producing a modified polymer and a diene polymer.

  As a technology to change the properties of natural polymers such as natural rubber and synthesized polymers themselves, terminal structure modification, functional groups are added directly to the side chain, or functional groups are added by grafting polymers. A technique is used (for example, the following patent documents 1 to 5). However, a method for simply introducing a functional group into the main chain structure has not been obtained irrespective of solution polymerization or emulsion polymerization. Further, in the conventional technique, the molecular weight may be unintentionally lowered, and it is considered that there is an adverse effect on the physical properties depending on the object to be used.

  Patent Document 6 listed below relates to a depolymerized natural rubber useful as an adhesive, a pressure-sensitive adhesive, a sealing agent, a caulking agent, a plasticizer, and the like, and deproteinized natural rubber dissolved in an organic solvent in the presence of a metal catalyst. It is disclosed that a liquid depolymerized natural rubber having a number average molecular weight of 2000 to 50000 is produced by depolymerization by oxidation. This document discloses that the main chain is decomposed by air oxidation to form a molecular chain having a carbonyl group at one end and a formyl group at the other end, and then the formyl group is recombined by aldol condensation. However, it does not disclose the point of rebonding the other carbonyl group. Further, in this document, depolymerization is performed in a solution of an organic solvent, and there is no description of recombination by making a system containing a decomposed polymer acidic or basic. The production method is for obtaining a telechelic liquid rubber having carbonyl groups at both ends, and is intended only to obtain a liquid rubber obtained by reducing the molecular weight of natural rubber. The molecular weight is controlled. However, it is not intended to modify the polymer by rearranging the main chain structure.

JP 2006-152157 A JP 2008-184572 A WO2005 / 118704 JP 2011-225681 A JP 2012-121993 A Japanese Patent Laid-Open No. 08-081505

  The present invention has been made in view of the above, and an object thereof is to provide a novel method for modifying a polymer, and more specifically, a modification capable of easily introducing an alkoxysilyl group into the main chain structure of a polymer. It is an object of the present invention to provide a polymer production method and a novel diene polymer in which an alkoxysilyl group is introduced into the main chain structure.

In order to solve the above problems, the method for producing a modified polymer according to the present invention decomposes a polymer having a carbon-carbon double bond in the main chain by oxidative cleavage of the carbon-carbon double bond. A system including a polymer having a reduced molecular weight and a trifunctional molecule having an alkoxysilyl group represented by the following formula (A) in the structure is basic when acidic, and acidic when basic. In this way, the acid-basicity is changed to bond the decomposed polymer and the trifunctional molecule to obtain a modified polymer having an alkoxysilyl group introduced into the main chain.

However, in formula (A), R ¹ , R ² and R ³ each represent an aldehyde group or a carbonyl group, and R ⁴ represents an alkyl group having 1 to 10 carbon atoms.

In the method for producing a modified polymer of the present invention, the decomposed polymer preferably includes a structure represented by the following formula (1) at the end.

However, in the formula (1), ^{R 5} represents a hydrogen atom or a methyl group.

  The trifunctional molecule having an alkoxysilyl group represented by the above formula (A) in its structure can be obtained by oxidative cleavage of a carbon-carbon double bond of a trifunctional molecule having at least one vinyl group.

In the said manufacturing method, the modified polymer which has at least 1 sort (s) of bond structure in a molecule | numerator among the bond structures represented by following formula (2)-(5) can be obtained.

However, in the formula (2) ~ (5), R 4 represents an alkyl group having 1 to 10 carbon atoms.

  In the production method of the present invention, a carbon-carbon double bond can be oxidatively cleaved using periodic acid. The reaction system is preferably an aqueous emulsion.

  A diene rubber polymer can be used as the polymer having a carbon-carbon double bond in the main chain, and examples of the diene rubber polymer include natural rubber and synthetic isoprene rubber.

  In the production method of the present invention, it is preferable to introduce 1 to 5 mol% of alkoxysilyl groups into the polymer main chain.

The diene polymer of the present invention has a linking group containing at least one of the bonding structures represented by the following formulas (2) to (5) in the molecule, and the diene polymer chain is interposed via this linking group. Shall be connected.

However, in the formula (2) ~ (5), R 4 represents an alkyl group having 1 to 10 carbon atoms.

  The diene polymer chain may be a diene rubber polymer chain.

  According to the present invention, the polymer is decomposed by oxidative cleavage of the double bond of the main chain to reduce the molecular weight, and then the decomposed polymer and the alkoxysilyl group represented by the following formula (A) are formed into a structure. An alkoxysilyl group can be easily incorporated into the main chain structure of a polymer by bonding a system containing a trifunctional molecule having an acidic or basic system. Thus, since a crosslinking point is formed by incorporating an alkoxysilyl group into the main chain structure, it becomes possible to supplement the sulfur crosslinking of a polymer such as natural rubber and improve its physical properties.

  Hereinafter, matters related to the implementation of the present invention will be described in detail.

  In the present embodiment, the polymer to be modified is a polymer containing a carbon-carbon double bond in the main chain, preferably a diene polymer, more preferably a diene rubber polymer. The diene polymer is a conjugated diene compound such as butadiene, isoprene, chloroprene, 2,3-dimethyl-1,3-butadiene, 2-methyl-1,3-pentadiene, 1,3-hexadiene, etc. It is a polymer obtained by using. These conjugated diene compounds may be used alone or in combination of two or more.

  The diene polymer includes a copolymer of a conjugated diene compound and another monomer other than the conjugated diene compound. Examples of other monomers include various vinyl compounds such as acrylonitrile and acrylate esters. These vinyl compounds may be used alone or in combination of two or more.

  More specifically, as the diene rubber polymer, various rubber polymers having isoprene units and / or butadiene units in the molecule are preferable. For example, natural rubber (NR), synthetic isoprene rubber (IR), butadiene rubber (BR). Styrene butadiene rubber (SBR), nitrile rubber (NBR), butadiene-isoprene copolymer rubber, and the like. Of these, natural rubber and synthetic isoprene rubber are preferably used.

  The diene rubber polymer to be modified is preferably a solid at normal temperature (23 ° C.), and therefore preferably has a number average molecular weight of 60,000 or more. Here, the solid state means a state having no fluidity. For example, when a rubber polymer is processed as it is as a material, plastic deformation is prevented without applying force at room temperature. The number average molecular weight of the diene polymer is preferably 60,000 to 1,000,000, more preferably 80,000 to 800,000, still more preferably 100,000 to 600,000.

  As the polymer to be modified, a polymer dissolved in a solvent can be used, but it is preferable to use an aqueous emulsion, that is, a latex, which is in a micellar form in water, which is a protic solvent. By using an aqueous emulsion, after the polymer is decomposed, the acid-basicity of the reaction field can be changed in this state to cause a binding reaction with a trifunctional molecule. Although the density | concentration (solid content concentration of a polymer) of an aqueous emulsion is not specifically limited, It is preferable that it is 5-70 mass%, More preferably, it is 10-50 mass%. If the solid content concentration is too high, the emulsion stability is lowered, the micelles are easily broken against pH fluctuations in the reaction field, and are not suitable for the reaction. On the other hand, when the solid content concentration is too small, the reaction rate becomes slow and lacks practicality.

  In order to oxidatively cleave the carbon-carbon double bond of the polymer, an oxidant can be used. For example, the oxidative cleavage can be performed by adding an oxidant to the aqueous emulsion of the polymer and stirring. Examples of the oxidizing agent include manganese compounds such as potassium permanganate and manganese oxide, chromium compounds such as chromic acid and chromium trioxide, peroxides such as hydrogen peroxide, perhalogen acids such as periodic acid, ozone, Examples thereof include oxygens such as oxygen. Among these, it is preferable to use periodic acid. For oxidative cleavage, a metal-based oxidation catalyst such as a salt or complex with a metal chloride or organic compound such as cobalt, copper, or iron may be used in combination. For example, air oxidation in the presence of the metal-based oxidation catalyst. May be.

  When two or more kinds of diene polymers are oxidatively cleaved, each polymer may be oxidatively cleaved by adding an oxidizing agent in a separate system. Alternatively, two or more kinds of polymers may be premixed and then mixed. You may oxidatively cleave together by adding an oxidizing agent.

The polymer is decomposed by the oxidative cleavage, and a polymer having a carbonyl group (> C═O) or a formyl group (—CHO) at the terminal is obtained. For example, when the polymer to be modified has an isoprene unit or a butadiene unit, a polymer having a structure represented by the following formula (1) at the end is generated.

In the formula, R ⁵ is a hydrogen atom or a methyl group. When the isoprene unit is cleaved, R ¹ is a methyl group at one cleavage end, and R ⁵ is a hydrogen atom at the other cleavage end, and the butadiene unit is cleaved. In this case, R ⁵ is a hydrogen atom at both cleavage ends. More specifically, the decomposed polymer has a structure represented by the above formula (1) at at least one end of its molecular chain, that is, as shown in the following formulas (7) and (8), A polymer in which the group represented by the formula (1) is directly bonded to one or both ends of the polymer chain is produced.

In Formulas (7) and (8), R ⁵ is a hydrogen atom or a methyl group, and the portion represented by the wavy line is a diene polymer chain. For example, when natural rubber is decomposed, the portion represented by a wavy line is a polyisoprene chain composed of a repeating structure of isoprene units.

  By decomposing the polymer by the oxidative cleavage, the molecular weight is decreased. Although the number average molecular weight of the polymer after decomposition is not particularly limited, it is preferably 3 to 500,000, more preferably 5 to 100,000, and still more preferably 1,000 to 50,000. In addition, although the amount of alkoxysilyl groups after recombination can be adjusted by the magnitude | size of the molecular weight after decomposition | disassembly, when the molecular weight at the time of decomposition | disassembly is too small, it will become easy to produce the coupling reaction in the same molecule.

After decomposing the polymer as described above, a reaction system including the decomposed polymer and a trifunctional molecule having an alkoxysilyl group represented by the following formula (A) in the structure is made acidic in the case of basic. If it is acidic, it is recombined by making it basic.

In the above formula (A), R ¹ , R ² and R ³ each represents an aldehyde group or a carbonyl group, and R ⁴ represents an alkyl group having 1 to 10 carbon atoms. Examples of the carbonyl group include a carboxyl group, a keto group having an alkyl group having 1 to 5 carbon atoms (-C (= O) R ', carbon number of R': 1 to 5), and an alkyl group having 1 to 5 carbon atoms. And an ester group having a group (-C (= O) OR ", carbon number of R": 1 to 5).

  The trifunctional molecule having an alkoxysilyl group represented by the formula (A) in its structure can be obtained by oxidative cleavage of a carbon-carbon double bond of a trifunctional molecule having at least one vinyl group. This oxidative cleavage reaction can be carried out in accordance with the oxidative cleavage reaction of the above polymer, and can also be carried out simultaneously with the oxidative cleavage reaction of the polymer. Preferred examples of the trifunctional molecule having at least one vinyl group include trivinylethoxysilane, trivinylmethoxysilane, 2,4,6-trimethyl-2,4,6-trivinylcyclotrisilazane, and trivinylsilane. Or the aldehyde derivative which oxidized the vinyl group etc. are mentioned.

The structure of the above formula (1) has two types of tautomerism and forms a bond structure represented by the following formulas (2) to (5) and those bonded to the original carbon-carbon double bond structure. Divided into things. In this embodiment, by controlling the pH of the reaction field, it is possible to give priority to the aldol condensation reaction and produce a polymer containing a bond structure represented by the formulas (2) to (5). In detail, some reaction systems, especially aqueous emulsions, have pH adjusted for stabilization. Depending on the method used for decomposition and the type and concentration of the chemical, the pH during decomposition is either acidic or basic. Stop by either. Therefore, it is preferable to make the reaction system basic when the reaction system at the time of decomposition is acidic so that the binding reaction that is the reverse reaction to cleavage proceeds preferentially, and conversely, When the reaction system is basic, it is preferable to make the reaction system acidic.

In the above formula (2) ~ (5), R 4 represents an alkyl group having 1 to 10 carbon atoms derived from ^{R 4} in the formula (A). Carbon atoms derived from R ¹ , R ^2, and R ³ are bonded to the silicon atoms in these formulas, and each has a bonded structure represented by formulas (2) to (5). The three bonding structures represented by the above formulas (2) to (5) bonded to one silicon atom may be the same as or different from each other.

Here, when a polymer having a terminal structure in which R ⁵ is a hydrogen atom and a trifunctional molecule represented by the formula (A) having an aldehyde group are bonded, the polymer is represented by the formula (4) by an aldol condensation reaction. A bond structure is formed, and water is desorbed from this to form a bond structure represented by Formula (5). When a polymer having a terminal structure in which R ⁵ is a hydrogen atom and a trifunctional molecule represented by the formula (A) having a carbonyl group are bonded to each other, a bonded structure represented by the formula (3) is obtained by an aldol condensation reaction. From this, when water is desorbed, a bond structure represented by the formula (2) is obtained. When alkoxysilyl groups are bonded to each other, a bond structure represented by the following formula (6) is obtained, but the amount of formation is small, and bond structures of formulas (2) to (5) are mainly generated.

.

However, in the formula (6), ^{R 4} represents an alkyl group having 1 to 10 carbon atoms derived from ^{R 4} in the formula (A).

In addition, for example, when a polymer having a terminal structure in which R ⁵ is a methyl group and a trifunctional molecule represented by the formula (A) having a carbonyl group are bonded, other than the above formulas (2) to (6) In some cases, bond structures are produced, but such bond structures are insignificant.

  When the reaction system is made basic, the pH of the reaction system for the binding reaction is preferably 7.5 to 13, and more preferably 8 to 10. On the other hand, when making a reaction system acidic, it is preferable that it is 4-6.8, More preferably, it is 5-6. In addition, when making it into acidic conditions, there exists a possibility of destroying the micelle of latex if acidity is raised too much. The pH can be adjusted by adding an acid or base to the reaction system, and is not particularly limited. Examples of the acid include hydrochloric acid, sulfuric acid, nitric acid, phosphoric acid, and the base includes hydroxylated. Sodium, potassium hydroxide, sodium carbonate, sodium hydrogen carbonate, etc. are mentioned.

  In the binding reaction, an acid or a base used for adjusting the pH serves as a catalyst for the binding reaction, and pyrrolidine-2-carboxylic acid, for example, can be used as a catalyst for controlling the reaction.

  After the binding reaction as described above, the water-based emulsion is coagulated and dried to obtain a solid modified polymer at room temperature.

  According to this embodiment, the coupling reaction represented by the above formulas (2) to (5) is introduced into the main chain by the coupling reaction as described above, and the modification has an alkoxysilyl group in the main chain. A polymer is obtained. That is, the modified polymer according to the embodiment has in the molecule a linking group containing at least one of the bonding structures represented by the above formulas (2) to (5), and the diene polymer chain has these linking groups. Through a directly connected structure.

Here, the diene polymer chain is a part of the molecular chain of the diene polymer that is the modification target. For example, in the case of a homopolymer of a conjugated diene compound, the diene polymer chain is composed of the conjugated diene compound. a configuration unit as ^{a 1,} - ^(a _{1) n} - is a repeating structure of ^{a 1,} represented by (n is an integer of 1 or more, preferably 10 to 10000, more preferably 50 to 1,000) . Further, in the case of a binary copolymer, the diene polymer chain has each constituent unit as A ¹ and A ² (at least one of A ¹ and A ² is a unit composed of a conjugated diene compound, and other units include And a unit composed of the above vinyl compound.), A repeating structure of A ¹ and A ² represented _by- (A ¹ ) _n- (A ² ) _m- (these may be random type or block type). n and m are each an integer of 1 or more, preferably 10 to 10000, more preferably 50 to 1000). In the case of a terpolymer, the diene-based polymer chain is composed of A ¹ , A ² and A ³ as constituent units (at least one of A ¹ , A ² and A ³ is a unit composed of a conjugated diene compound. And other units include units composed of the above vinyl compounds.), A ¹ , A ² and A ³ represented _by- (A ¹ ) _n- (A ² ) _m- (A ³ ) _p- (These may be random type or block type. N, m, and p are each an integer of 1 or more, preferably 10 to 10,000, more preferably 50 to 1000). The same applies to quaternary copolymers or more.

More specifically, for example, when natural rubber or synthetic isoprene rubber is used as a modification target, the diene polymer chain is a polyisoprene chain represented by the following formula (9), which consists of a repeating structure of isoprene units. . The diene polymer chain is preferably a diene rubber polymer chain such as polyisoprene chain or polybutadiene chain. In addition, in Formula (9), n is an integer greater than or equal to 1, Preferably it is 10-10000, More preferably, it is 50-1000.

  One or more bond structures represented by the above formulas (2) to (5) are included in one molecule of the modified polymer, and usually a plurality of bond structures are included in one molecule. When two or more types are included, a plurality of any one of the bonding structures represented by the above formulas (2) to (5) may be included, or two or more types may be included. The introduction rate of the alkoxysilyl group, that is, the modification rate, is the total content of the bond structures of the formulas (2) to (5), preferably 0.1 to 20 mol%, more preferably 0.5. It is 10 mol%, More preferably, it is 1-5 mol%. If the introduction amount of the alkoxysilyl group is too small, the effect of improving the deterioration resistance of the rubber intended by the present invention cannot be obtained. On the other hand, if the amount is too large, the crosslinking points will increase so much that gelation may occur in the reaction. . Here, the content (modification rate) of the bond structure is the ratio of the number of moles of the bond structure to the number of moles of all the structural units constituting the modified polymer. For example, in the case of natural rubber, This is the ratio of the number of moles of bond structure to the total number of moles of bond structure.

  For example, in the case of natural rubber or synthetic isoprene rubber (that is, when the diene polymer chain has an isoprene unit), all of the bond structures represented by the formulas (2) to (5) are usually included. ) Is mainly included, and in that case, the content of the bond structure represented by the formula (2) is preferably 0.001 to 20 mol%, more preferably 0.05 to 10%. It is mol%, More preferably, it is 0.5-5 mol%.

  The number average molecular weight of the modified polymer is preferably 60,000 or more, more preferably 60,000 to 1,500,000, particularly preferably 100,000 to 1,200,000. As described above, the molecular weight of the modified polymer is preferably set to be equal to that of the original polymer by recombination via a trifunctional molecule as described above. While avoiding adverse effects, alkoxysilyl groups can be introduced into the main chain of the polymer. Of course, a polymer having a molecular weight smaller than that of the original polymer may be obtained. The weight average molecular weight of the modified polymer is not particularly limited, but is preferably 70,000 or more, more preferably 100,000 to 2,000,000, still more preferably 300,000 to 1,700,000.

  According to the present embodiment, as described above, the polymer is decomposed by oxidative cleavage of the double bond of the main chain to reduce the molecular weight, and then the decomposed polymer is represented by the following formula (A). By changing the acid basicity of a system containing a trifunctional molecule having an alkoxysilyl group in its structure, a modified polymer in which an alkoxysilyl group is introduced is produced by bonding the decomposed polymer and the trifunctional molecule. Therefore, it is possible to converge to a more uniform structure by monodispersing the polymer. That is, the molecular weight distribution of the modified polymer can be made smaller than the molecular weight distribution of the original polymer. This is because the shorter the polymer decomposed by oxidative cleavage, the higher the reactivity and the easier the bonding, so it is considered that the molecular weight is made uniform by decreasing the number of short polymers.

  Further, according to the present embodiment, the reaction for oxidative cleavage is controlled by adjusting the type and amount of the oxidizing agent that is a drug that dissociates the double bond, the reaction time, and the pH at the time of recombination. The coupling reaction can be controlled by adjusting the catalyst, reaction time, etc., and the molecular weight of the modified polymer can be controlled by these controls. Therefore, the number average molecular weight of the modified polymer can be set equal to that of the original polymer, and can be set lower than that of the original polymer.

  Further, when the polymer main chain is decomposed and re-bonded, the above-mentioned bonding structure is inserted as a structure different from the main chain, and the bonding point of the segment of the main chain structure is functionalized. That is, a highly reactive structure is introduced into the molecular main chain, and the characteristics of the original polymer can be changed. As described above, the method of the present embodiment changes the main chain structure itself of the polymer that is neither grafted nor directly added nor ring-opened, and is clearly different from the conventional modification method, and the main chain structure has an alkoxysilyl group. Groups can be introduced easily. In addition, a modified polymer having a novel structure can be produced by modifying the main chain structure of a natural polymer such as natural rubber, and the characteristics of the polymer can be changed.

  The modified polymer according to this embodiment can be used as a polymer component in various polymer compositions, and is not particularly limited. However, a modified diene rubber obtained by modifying a diene rubber is obtained, and the modified diene rubber is used in various ways. It is preferable to use it as a rubber component in the rubber composition. When used in a rubber composition, the modified diene rubber may be used alone or as a rubber component by blending with another diene rubber. In addition, the rubber composition can contain a filler such as silica and carbon black together with the rubber component, and as other additives, softeners, plasticizers, anti-aging agents, zinc white, stearic acid, and the like. Various additives generally used in rubber compositions such as a vulcanizing agent and a vulcanization accelerator can also be blended. The use of the rubber composition is not particularly limited, and the rubber composition can be used for various rubber members such as tires, anti-vibration rubbers, and conveyor belts.

  Examples of the present invention will be described below, but the present invention is not limited to these examples. The measurement methods used in the following examples and comparative examples are as follows.

[PH]
It was measured using a portable pH meter “HM-30P type” manufactured by Toa DK Corporation.

[Number average molecular weight (Mn), weight average molecular weight (Mw), molecular weight distribution (Mw / Mn)]
Mn, Mw and Mw / Mn in terms of polystyrene were determined by measurement with gel permeation chromatography (GPC). Specifically, the measurement sample used was 0.2 mg dissolved in 1 mL of THF. “LC-20DA” manufactured by Shimadzu Corporation was used, and the sample was filtered and passed through a column (“PL Gel 3 μm Guard” manufactured by Polymer Laboratories × 2) at a temperature of 40 ° C. and a flow rate of 0.7 mL / min. Detection was performed by “RI Detector” manufactured by System.

[Binder structure content]
The contents of the bonded structures (2) to (5) were measured by NMR. The NMR spectrum was measured by “400ULTRASHIELDTM PLUS” manufactured by BRUKER. 1 g of the polymer was dissolved in 5 mL of deuterated chloroform, 87 mg of acetylacetone chromium salt was added as a relaxation reagent, and the measurement was performed with an NMR 10 mm tube.

For the bond structure of formula (2), the carbon peak next to silicon in ¹³ C-NMR is at 130 ppm. For the bond structure of formula (3), the carbon peak next to silicon in ¹³ C-NMR is at 55 ppm. For the bond structure of formula (4), the carbon peak next to silicon in ¹³ C-NMR is at 204 ppm. For the bond structure of formula (5), the carbon peak next to silicon in ¹³ C-NMR is at 132 pm. Therefore, the structural amount (number of moles) of each peak was determined by the ratio with the base polymer component.

Regarding the number of moles of each unit in the base polymer component, in the isoprene unit, carbon on the opposite side of the methyl group across the double bond and the peak of hydrogen (= CH-) bonded thereto, that is, by ¹³ C-NMR. Calculations were based on the 122 ppm peak. Further, in each structural unit represented by the formulas (2) to (5), the peaks of each of the three carbons adjacent to the silyl group are detected. Therefore, 1/3 (3 of the amount derived from those peaks) 1) was defined as each bond structure content (mol%), and as the alkoxysilyl group content, the total amount of each bond structure content of formulas (2) to (5) was shown.

[Example 1: Synthesis of modified polymer A]
As a polymer to be modified, natural rubber latex (manufactured by Regex Corp., high ammonia-containing natural rubber “HA-NR”, DRC (Dry Rubber Content) = 60 mass%) was used. When the molecular weight of the unmodified natural rubber contained in the natural rubber latex was measured, the weight average molecular weight was 2.02 million, the number average molecular weight was 510,000, and the molecular weight distribution was 4.0.

The polymer mass 100g of the natural rubber latex was adjusted to DRC30 mass%, periodic acid _{(H 5} IO 6) 1.65g was added, and the mixture was stirred for 3 hours at 23 ° C.. Thus, by adding periodic acid to the polymer in the emulsion state and stirring, the double bond in the polymer chain was oxidatively decomposed, and a polymer having a structure represented by the above formula (1) was obtained. The obtained decomposition polymer had a weight average molecular weight of 13,500, a number average molecular weight of 5,300, a molecular weight distribution of 2.6, and the pH of the reaction solution after decomposition was 6.2.

A reaction product obtained by adding 0.01 g of periodic acid (H ₅ IO ₆ ) to 3.9 g of trivinylethoxysilane and stirring the mixture at 23 ° C. for 1 hour, and pyrrolidine-2-carboxylic acid 0 as a catalyst. 0.1 g was added and 1N sodium hydroxide was added so that the pH of the reaction solution became 10, and the mixture was reacted by stirring for 24 hours at 23 ° C., then reprecipitated in methanol, washed with water, The polymer was dried at 30 ° C. for 24 hours by a circulation dryer to obtain a modified polymer A solid at room temperature.

  By adding sodium hydroxide to the oxidatively decomposed reaction system and forcibly changing the reaction system to basic, the effect of periodic acid added during oxidative cleavage is neutralized. Thus, the recombination reaction could be prioritized, and a modified natural rubber (modified polymer A) containing a bonded structure represented by the above formulas (2) to (5) was obtained. In the above, pyrrolidine-2-carboxylic acid is used as a catalyst, but this is for accelerating the reaction, and the reaction proceeds even without it.

  As shown in Table 1 below, the obtained modified polymer A has a weight average molecular weight Mw of 1,220,000, a number average molecular weight Mn of 620,000, a molecular weight distribution Mw / Mn of 2.5, and the content of the above bonded structure is represented by the formula (2) is 1.0 mol%, formula (3) is 0.1 mol%, formula (4) is 0.1 mol%, and formula (5) is 0.3 mol%, for a total of 1.5 mol%. Mol%. Thus, the modified polymer A had a number average molecular weight substantially equal to that of the unmodified natural rubber. Further, the molecular weight distribution was smaller than that of the unmodified natural rubber, and the uniformity was excellent.

[Examples 2 and 3: Synthesis of modified polymers B and C]
The reaction time during oxidative decomposition, the amount of periodic acid added, the pH adjuster and pH added during the recombination reaction, and the amount of catalyst were changed as shown in Table 1 below, and the others were the same as in Example 1. Solid modified polymers B and C were synthesized. Table 1 shows the contents of Mw, Mn, Mw / Mn and each bond structure of the obtained modified polymers B and C. Also in the modified polymers B and C, the above bond structure having an alkoxysilyl group was introduced into the main chain, and the molecular weight distribution was smaller than that of the unmodified natural rubber and was excellent in uniformity. In addition, the molecular weight could be controlled by changing the above conditions.

  Comparative Example 1 in Table 1 was obtained by coagulating and drying the natural rubber latex (Regex Corp., high ammonia-containing natural rubber “HA-NR”, DRC = 60% by mass) without modification. Unmodified natural rubber. Comparative Example 2 is a decomposed polymer obtained by coagulating and drying the same natural rubber latex by only oxidative cleavage.

[Use Examples / Comparative Use Examples: Preparation and Evaluation of Rubber Composition]
Using a Banbury mixer, according to the formulation (parts by weight) shown in Table 2 below, first, in the first mixing stage, other compounding agents excluding sulfur and vulcanization accelerator are added and kneaded, and then kneaded. In the final mixing stage, sulfur and a vulcanization accelerator were added to the obtained kneaded product and kneaded to prepare a rubber composition. Details of each component in Table 2 excluding the rubber component are as follows.

・ Silica: “Nip Seal AQ” manufactured by Tosoh Silica Corporation
・ Carbon black: “Seast 3” manufactured by Tokai Carbon Co., Ltd.
Silane coupling agent: bis (3-triethoxysilylpropyl) tetrasulfide, “Si69” manufactured by Evonik Degussa
・ Zinc flower: “Zinc flower 1” manufactured by Mitsui Mining & Smelting Co., Ltd.
Anti-aging agent: “NOCRACK 6C” manufactured by Ouchi Shinsei Chemical Industry Co., Ltd.
・ Stearic acid: “Lunac S-20” manufactured by Kao Corporation
・ Process oil: “X-140” manufactured by Japan Energy Co., Ltd.
・ Sulfur: Hosoi Chemical Co., Ltd. “Powder sulfur for rubber 150 mesh”
・ Vulcanization accelerator: “Noxeller CZ” manufactured by Ouchi Shinsei Chemical Co., Ltd.

  About each obtained rubber composition, vulcanize | curing at 160 degreeC x 20 minutes, a test piece of a predetermined shape is produced, reversion resistance and deterioration resistance are evaluated using the obtained test piece, and A dynamic viscoelasticity test was performed to measure tan δ (0 ° C.) and tan δ (60 ° C.). Each measurement / evaluation method is as follows.

・ Reversion resistance: Measured vulcanization torque at 150 ° C for 90 minutes with “RHEOMETER MDR2000” manufactured by ALPHA TECHNOLOGIES, and calculated the change in the value after 30 minutes from the time when the maximum value of torque was shown. About the reciprocal number of each, it represented by the index | exponent which made the value of each control 100. The larger the index, the smaller the decrease in torque and the better the reversion resistance.

・ Deterioration resistance: Tensile tests were performed on each rubber sample after vulcanization and the sample deteriorated for 14 days in a hot-air circulating oven set at 100 ° C., and the 300% modulus value was measured. The reciprocal of the measured value was expressed as an index with the value of each control as 100. As a tensile test, a tensile test (dumbbell-shaped No. 3 type) based on JIS K6251 was performed. The larger the index, the smaller the decrease in M300 and the better the deterioration resistance.

Tan δ (0 ° C.): A loss factor tan δ was measured using a USM Rheospectrometer E4000 under conditions of a frequency of 50 Hz, a static strain of 10%, a dynamic strain of 2%, and a temperature of 0 ° C. Is expressed as an index with 100 being 100. Tan δ at 0 ° C. is generally used as an index of grip performance (wet performance) on wet road surfaces in tire rubber compositions. The larger the index, the larger tan δ and the better the wet performance. Show.

Tan δ (60 ° C.): tan δ was measured in the same manner as tan δ (0 ° C.) except that the temperature was changed to 60 ° C., and the reciprocal number was expressed as an index with the value of each comparative test example being 100. Tan δ at 60 ° C. is generally used as an index of low heat buildup in tire rubber compositions. The larger the index, the smaller tan δ, and thus the less heat is generated, resulting in low fuel consumption as a tire. It is excellent in.

  As shown in Table 2, the rubber compositions of Use Examples 1 to 3 using the modified polymers of the Examples are used in each comparative use example using unmodified natural rubber and rubber that has not been recombined with only the modified rubber. On the other hand, it was excellent in tan δ and the like.

  The modified polymer according to the present invention can be used as a polymer component blended in various polymer compositions including a rubber composition.

Claims (11)

A polymer having a carbon-carbon double bond as a main chain, decomposed by oxidative cleavage of the carbon-carbon double bond to reduce the molecular weight, and an alkoxysilyl group represented by the following formula (A) A system comprising a trifunctional molecule having a structure of a base, when the acid is basic, the acid basicity is changed so as to be acidic, and in the case of basic, the decomposed polymer and the trifunctional molecule are changed. To obtain a modified polymer having an alkoxysilyl group introduced into the main chain.

However, in formula (A), R ¹ , R ² and R ³ each represent an aldehyde group or a carbonyl group, and R ⁴ represents an alkyl group having 1 to 10 carbon atoms. The method for producing a modified polymer according to claim 1, wherein the decomposed polymer includes a structure represented by the following formula (1) at a terminal.

However, in the formula (1), ^{R 5} represents a hydrogen atom or a methyl group.   A trifunctional molecule having an alkoxysilyl group represented by the formula (A) in its structure is obtained by oxidative cleavage of a carbon-carbon double bond of a trifunctional molecule having at least one vinyl group. The method for producing a modified polymer according to claim 1 or 2. 4. The modified polymer according to claim 1, wherein the modified polymer has in the molecule at least one type of bond structure represented by the following formulas (2) to (5). A method for producing the modified polymer according to 1.

However, in the formula (2) ~ (5), R 4 represents an alkyl group having 1 to 10 carbon atoms.   The method for producing a modified polymer according to any one of claims 1 to 4, wherein the carbon-carbon double bond is oxidatively cleaved using periodic acid.   The method for producing a modified polymer according to any one of claims 1 to 5, wherein the reaction system is an aqueous emulsion.   The method for producing a modified polymer according to any one of claims 1 to 6, wherein the polymer having a carbon-carbon double bond in the main chain is a diene rubber polymer.   The method for producing a modified polymer according to claim 7, wherein the diene rubber polymer is natural rubber or synthetic isoprene rubber.   The method for producing a modified polymer according to any one of claims 1 to 8, wherein 1 to 5 mol% of an alkoxysilyl group is introduced into the polymer main chain. A diene polymer having a linking group containing at least one of the bonding structures represented by the following formulas (2) to (5) in the molecule, wherein diene polymer chains are linked via the linking group .

However, in the formula (2) ~ (5), R 4 represents an alkyl group having 1 to 10 carbon atoms.   The diene polymer according to claim 10, wherein the diene polymer chain is a diene rubber polymer chain.