JPH04246454A - Heat-stabilized block copolymer composition - Google Patents

Abstract

PURPOSE:To obtain the title composition of excellent heat stability by mixing a block copolymer comprising a monoalkenyl aromatic compound and a conjugated diene with a specified phenolic stabilizer. CONSTITUTION:100 pts.wt. block copolymer comprising at least one monoalkenyl aromatic compound, polymer segment and at least one conjugated diene polymer segment, and having a monoalkenyl aromatic compound content of 5-95wt.% or a mixture thereof, and a thermoplastic resin and/or a rubbery polymer is mixed with 0.005-0.05 pt.wt. stabilizer of a phenolic compound of the formula (wherein R1 and R3 are each CH2-S-R5, R5 is 1-18 C alkyl; R2 is hydrogen or methyl; and R4 is 1-8 C alkyl or 5-12 C cycloalkyl) and 0.1-2.0 pts.wt. at least one stabilizer selected between a phenolic compound other than the compound of the above formula and a phosphorus compound.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention relates to a block copolymer consisting of a monoalkenyl aromatic compound and a conjugated diene, or a mixture of the block copolymer and a thermoplastic resin and/or rubbery polymer, and a specific phenol. The present invention relates to a heat-stabilized block copolymer composition comprising a system stabilizer and having excellent heat stability.

0002

[Prior Art] Block copolymers consisting of monoalkenyl aromatic hydrocarbons and conjugated dienes can be used to produce vulcanized natural rubber or vulcanized natural rubber without vulcanization when the monoalkenyl aromatic hydrocarbon content is relatively small. It has the same elasticity as synthetic rubber at room temperature and the same processability as thermoplastic resin at high temperatures, so it is widely used in the fields of footwear, plastic modification, asphalt, adhesives, etc.

[0003] Furthermore, when the content of monoalkenyl aromatic hydrocarbons is relatively high, a thermoplastic resin that is transparent and has excellent impact resistance can be obtained. At the same time, the number of uses is also becoming more diverse. However, block copolymers consisting of monoalkenyl aromatic hydrocarbons and conjugated dienes have poor thermal stability because they have carbon-carbon double bonds in their molecules.
The problem is that the properties of the block copolymer itself, such as elastic properties, adhesion, and impact resistance, cannot be sufficiently improved. Therefore, in order to improve the thermal stability of such block copolymers, phenolic stabilizers, phosphorus stabilizers, sulfur stabilizers, etc. are used.

0004

[Problems to be Solved by the Invention] For example, BHT (2,6-
In the case of di-tert-butyl-4-methylphenol), although it has a relatively high antioxidant function and heat resistance, it easily volatilizes when the molding temperature is high or the molding time is long. It was necessary to use large quantities. On the other hand, when phosphorus-based stabilizers and sulfur-based stabilizers are used in combination as secondary stabilizers, the thermal stabilization effect is improved, but phosphorus-based stabilizers have problems with hydrolysis and sulfur-based stabilizers Under relatively harsh conditions such as high temperatures, the agent may easily become colored or emit an odor, making it difficult to obtain stable effects.

[0005] Other stabilizers also have similar problems such as being easily colored, and their thermal stabilizing effects have not yet been sufficient. As mentioned above, the thermal stabilizing effect of conventional stabilizers is limited, even when used alone or in combination of several kinds. Therefore, depending on the industrial field in which it is used, it is not possible to obtain a product that is satisfactory in this respect, and a block copolymer composition that has truly high thermal stability has been desired for a long time.

[0006]

[Means to solve the problem] In this current situation,
The present inventors have conducted intensive research on methods for obtaining block copolymer compositions that have excellent physical property stability under high-temperature heating and are highly effective in suppressing the generation of gel-like substances. We discovered that it is possible to obtain a block copolymer composition with excellent thermal stability by combining a small amount of a stabilizer, a specific phenolic compound, which has a surprisingly high synergistic effect that cannot be predicted from agent combination technology. , led to the present invention.

That is, the present invention has: (a) a polymer segment mainly composed of at least one monoalkenyl aromatic compound and at least one polymer segment mainly composed of a conjugated diene; A block copolymer having a compound content of 5 to 95% by weight, or the block copolymer and a thermoplastic resin and/or
or a mixture with a rubbery polymer,...100 parts by weight (b
) A stabilizer which is a phenolic compound represented by the following general formula [I]...0.005 to 0.052 parts by weight

00
09]

[Chemical formula 1]

(wherein R1 and R3 are -CH2-
S-R5, where R5 represents an alkyl group having 1 to 18 carbon atoms. R2 represents a hydrogen atom or a methyl group. R4 represents an alkyl group having 1 to 8 carbon atoms or a cycloalkyl group having 5 to 12 carbon atoms. ) (c) At least one stabilizer selected from phenolic compounds and/or phosphorus compounds other than the following general formula [I], characterized by consisting of 0.1 to 2.0 parts by weight. , relates to thermally stabilized block copolymer compositions. The present invention will be explained in detail below.

The block copolymer used in the present invention is
It has at least one polymer segment based on a monoalkenyl aromatic compound and at least one polymer segment based on a conjugated diene, and the monoalkenyl aromatic compound content is 5 to 95% by weight, preferably 10-90
% by weight of a block copolymer or a mixture of the block copolymer and a thermoplastic resin and/or rubbery polymer.

Such a block copolymer exhibits properties as a thermoplastic elastomer when the content of the monoalkenyl aromatic compound is 60% by weight or less, preferably 55% by weight or less; When the amount exceeds 60% by weight, preferably 65% by weight or more, it exhibits properties as a thermoplastic resin. If the monoalkenyl aromatic compound content is less than 5% by weight, the block copolymer will have poor mechanical properties such as tensile strength, which is a desirable property as a thermoplastic elastomer, and if the monoalkenyl aromatic compound content is 95% by weight or more, is inferior in mechanical strength such as impact resistance, which is a desirable property as a thermoplastic resin.

Examples of the monoalkenyl aromatic compound used here include monomers such as styrene, α-methylstyrene, p-methylstyrene, m-methylstyrene, o-methylstyrene, and p-tert-butylstyrene. Among them, styrene is preferred. These monomers may be used alone or in combination of two or more.

On the other hand, examples of conjugated dienes include 1,3
-butadiene, isoprene, 2,3-dimethyl-1,3
Examples include monomers such as -butadiene and 1,3-pentadiene, of which 1,3-butadiene and isoprene are preferred. These monomers may be used alone or in combination of two or more.

The block copolymer used in the present invention is
The following general formula: (A-B)n, (A-B)n A, (A-B)n X
(In the formula, A is a polymer block mainly composed of a monoalkenyl aromatic compound, B is a conjugated diene compound polymer or a polymer block mainly composed of a conjugated diene, and X is, for example, silicon tetrachloride, tetrachloride Represents residues of coupling agents such as tin, bisphenol-type epoxy compounds, epoxy soybean oil, polyhalogenated hydrocarbons, and carboxylic acid esters, or residues of polyfunctional organolithium compounds. n is an integer of 1 or more.) It is a block copolymer consisting of a monoalkenyl aromatic compound represented by the formula and a conjugated diene.

[0016] Furthermore, the polymer block mainly consisting of a monoalkenyl aromatic compound refers to a monopolymer block of a monoalkenyl aromatic compound or a monopolymer block mainly composed of a monoalkenyl aromatic compound.
A monoalkenyl aromatic compound-conjugated diene copolymer block containing more than 0% by weight is shown. The polymer block mainly containing conjugated diene refers to a conjugated diene homopolymer block or a conjugated diene-monoalkenyl aromatic compound copolymer block containing more than 50% by weight of conjugated diene.

Monoalkenyl aromatic hydrocarbons in the copolymer block may be distributed uniformly or non-uniformly (tapered).
may be distributed. A plurality of uniformly distributed portions and/or non-uniformly distributed portions may coexist in each block. Further, the block copolymer used in the present invention may be any mixture of block copolymers represented by the above general formula.

The number average molecular weight of the block copolymer used in the present invention is from 10,000 to 1,000,000, preferably from 20,000 to 800,000. If the number average molecular weight is less than 10,000, mechanical properties such as tensile strength etc. deteriorate, which is not preferable. In addition, if the number average molecular weight exceeds 1,000,000, the viscosity is too high, which is undesirable because it causes poor dispersion and poor processability when compounded for various uses, such as adhesives and materials for footwear. .

The above general formula (AB)n, (AB)n
The block copolymer represented by A, (A-B)n Alternatively, it can be obtained by a so-called anionic polymerization method using an organic lithium compound as an initiator as described in JP-A-58-136603.

For example, polystyrene-polybutadiene-
When obtaining a block copolymer with an A-B-A structure represented by polystyrene, a predetermined amount of n-butyllithium is added to the styrene monomer mixed in the above-mentioned inert solvent such as cyclohexane under an inert gas atmosphere such as nitrogen. An organolithium initiator such as the following is added to form a polystyrene block, and then a butadiene monomer mixed solvent is added to form a polystyrene-polybutadiene type 2 polymer. After that, styrene monomer is further added to achieve the desired A-
There is a method for obtaining a type 3 block copolymer having a B-A structure.

In addition, it is also possible to obtain a block copolymer having the (A-B)nX structure by adding a coupling agent such as silicon tetrachloride after forming the type 2 block polymer. In some cases, so-called polar compounds such as tetrahydrofuran, diethylene glycol dimethyl ether, and tetramethylethylene diamine may be added to the polymerization system. The method for producing the block copolymer is not particularly limited, and various methods may be used depending on the desired polymer.

The composition of the present invention is characterized in that 0.005 to 0.05 parts by weight of the phenolic compound represented by the general formula (I) is blended per 100 parts by weight of the block copolymer. The blending amount of general formula [I] is 0.00
If it is less than 5 parts by weight, the stabilizing effect will be small, and the effect of combined use with a phenol compound and/or a phosphorus compound other than the general formula [I] will also be reduced. Moreover, if the blending amount exceeds 0.05 parts by weight, the block copolymer composition will become intensely colored when heated at high temperature for a long time, which is not preferable. A more preferable amount is 0.02 to 0.05 parts by weight.

In the compound represented by the general formula [I] used in the present invention, the substituents R1 and R3 are:
It is represented by -CH2-S-R5, where R5 is an alkyl group having 1 to 18 carbon atoms, preferably an n-octyl group or an n-dodecyl group. The substituent R2 is a methyl group or a hydrogen atom, and when the substituent R4 is other than a methyl group, it represents a methyl group.

The substituent R4 as carbon atoms 1 to 8 is
Examples include methyl group, ethyl group, n-butyl group, sec-butyl group, tert-butyl group, etc., but preferably,
It is a methyl group or a tert-butyl group. carbon atom 5
Examples of the substituent R4 as a cycloalkyl group in 12 to 12 include a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, a cyclooxyl group, and preferably a cyclohexyl group.

Specific examples of the phenolic compound represented by the general formula [I] include 2,4-bis(n-octylthiomethyl)-6-methylphenol, 2,4-bis(n-
dodecylthiomethyl)-6-methylphenol, 2,4
-bis(phenylthiomethyl)-3-methyl-6-te
Examples include rt-butylphenol. Most preferably 2,4-bis(n-octylthiomethyl)-6-
It is methylphenol.

Furthermore, the composition of the present invention has the general formula [I
0.1 to 2.0 parts by weight of at least one type of stabilizer selected from phenolic compounds and/or phosphorus compounds other than the above are essential. The amount of phenolic compound and/or phosphorus compound other than the general formula [I] is 0
．． If the amount is less than 0.01 parts by weight, the stabilizing effect will be small, and the effect of combined use with the general formula [I] will also be small. Also, the blending amount is 2.0
Even if the amount exceeds 1 part by weight, there is no substantial effect on thermal stabilization, and unnecessary addition is economically disadvantageous. A more preferable amount is 0.2 to 1.5 parts by weight.

A particularly preferred composition of the present invention is a composition of the general formula [I] per 100 parts by weight of the block copolymer.
] and 0.02 to 0.05 parts by weight of a phenolic compound represented by the above general formula [I].
The best combination is 1 to 1.0 parts by weight of a phosphorus compound, 0.1 to 1.0 parts by weight of a phosphorus compound, and 0.1 to 1.0 parts by weight of a phosphorus compound. Examples of phenolic compounds other than the above general formula [I] include the following general formulas [II] and [II
I], [IV], [V], etc.

[0028]

[0029]

[Case 2] (In the above formula, R6 is

[0030]

[Formula 3] R7 is an alkyl group having 2 to 22 carbon atoms, R8 to R
12 is a hydrogen atom or an alkyl group having 1 to 6 carbon atoms. However, two or more of R8 to R12 are alkyl groups. )

Specific examples of the phenolic compounds of formulas [II] to [V] will be explained below. [II] As a compound represented by formula, n-octadecyl-3-(3',5'-di-tert-butyl-4'-
hydroxyphenyl) propionate. Specific examples of the compound represented by formula [III] include tetrakis-[methylene-3-(3',5'-di-tert
-butyl-4'-hydroxy-phenyl)propionate]-methane. [IV] Specific examples of compounds represented by formula include 1,3
,5-trimethyl-2,4,6-tris(3,5-di-
Examples include tert-butyl-4-hydroxybenzyl)benzene. Specific examples of the compound represented by [V] include 2,6-di-tert-butyl-4-methylphenol, 2,6-
Examples include di-tert-butyl-4-ethylphenol.

Specific examples of phosphorus compounds include tris(nonylphenyl)phosphite, cyclic neopentanetetrayl bis(octadecylphosphite), and tris(2,4-di-tert-butylphenyl)phosphite. Examples include.

The composition of the present invention comprises a phenolic compound represented by the general formula [I] and the general formulas [II] to [V
], etc., but in some cases,
Furthermore, at least one kind selected from stabilizers such as sulfur-based compounds, ultraviolet absorbers such as benzotriazole-based compounds, and light stabilizers such as hindered amine-based compounds may be blended.

Specific examples of such sulfur-based compounds include pentaerythol-tetrakis-(β-lauryl-thio-propionate), dilauryl-3,3'-thiodipropionate, and dimyristyl-3,3'- Examples include thiodipropionate and distearyl-3,3'-thiodipropionate. Thermal stability can also be improved by combining such sulfur-based compounds with the composition of the present invention.

Specific examples of penzotriazole compounds and hindered amine compounds include 2-(2'-hydroxy-5'-methylphenyl)benzotriazole, 2
-(2'-hydroxy-5'-tert-octylphenyl)benzotriazole, 2-(2'-hydroxy-
3',5'-di-tert-butylphenyl)benzotriazole, 2-(2'-hydroxy-3',5'-di-tert-butylphenyl)-5-chlorobenzotriazole, 2-(2'- Hydroxy-3'-tert-
benzotriazole compounds such as butyl-5'-methylphenyl)-5-chlorobenzotriazole;

00
33] Bis(2,2,6,6-tetramethyl-4-piperidyl)sebacate, dimethyl-1-(2-hydroxyethyl)-4-hydroxy-2,2,6,6-succinate
Tetramethylpiveridine polycondensate, poly[(6-(1,
1,3,3-tetramethylbutyl)imino-1,3,5
-triazine-2,4-diyl] [(2,2,6,6-
Examples include hindered amine compounds such as tetramethyl-4-piperidyl)imino]hexamethylene [[2,2,6,6-tetramethyl-4-piperidyl)imino].

By combining such benzotriazole compounds, hindered amine compounds, etc. with the composition of the present invention, its light resistance can be further improved. The composition of the present invention is prepared by deactivating the living block copolymer solution obtained by the method described above with a suitable deactivating agent such as water, alcohol, or acid, and then adding the compound represented by the general formula [I] and the After adding a predetermined amount of a phenolic compound and/or phosphorus compound such as general formulas [II] to [V], or directly adding the entire amount to the solution and uniformly dispersing it, steam stripping or heat treatment is performed. It can be obtained by removing the solvent with a roll or the like.

Alternatively, a part of the phenolic compound and/or phosphorus compound of general formulas [I], [II] to [V], etc. is added to the block copolymer solution, and a solid block is prepared by the above method. After obtaining the copolymer composition, it can also be obtained by adding and mixing the remaining amount using a kneading machine such as a roll, a Banbury mixer, a kneader, or an extruder. The method of blending these compounds (stabilizers) is not particularly limited, and methods other than those described above may be used, and an appropriate method may be used depending on the situation. phosphorus compounds,
The same applies to the method of blending the sulfur compound, ultraviolet absorber, and light stabilizer.

The block copolymer composition of the present invention can be used by blending it with polystyrene resins such as polystyrene, impact-resistant polystyrene, ABS resins, and other engineering resins, and can also be used with polystyrene, polypropylene, etc. It is also possible to use it by blending it with a polyolefin resin. The block copolymer composition can also be suitably used as a hot melt adhesive-like base material by blending it with a tackifier resin or oil, or by blending it with straight asphalt, blown asphalt, etc. I can do it.

The block copolymer composition of the present invention may contain softeners, reinforcing agents, flame retardants, blowing agents,
It is also possible to add additives such as plasticizers and colorants.

[0038]

[Example] In order to explain the present invention in more detail, reference examples, working examples, and comparative examples are shown below. This is not intended to limit the scope of the present invention.

[0039]

[Reference example] Production of block copolymer. The block copolymers used in the examples of the present invention were produced as follows. After thoroughly purging a 40L stainless steel reactor equipped with a jacket and a stirrer with nitrogen, cyclohexane 17.60
0 g of tetrahydrofuran, 5.3 g of tetrahydrofuran, and 480 g of styrene (referred to as primary styrene) were charged, warm water was passed through the jacket, and the temperature of the contents was set at about 70°C. After that, add an appropriate amount of n-butyllithium (cyclohexane solution),
Polymerization of the first styrene was started. Ten minutes after the primary styrene was almost completely polymerized, 2,240 g of butadiene (1,3-butadiene) was added to continue the polymerization, and after the butadiene was almost completely polymerized and the maximum temperature was reached, 1
After 5 minutes, 480 g of styrene (referred to as secondary styrene) was added again to continue the polymerization, and after the secondary styrene was almost completely polymerized, the polymerization was completed by holding for another 15 minutes. - The active species were completely deactivated by adding 3 moles of water per mole of butyllithium.

The following stabilizers were used. AO-I: 2,4-bis(n-octylthiomethyl)-6-methylphenol AO-II: n-octadecyl-3-(3',5'-di-tert-butyl-4'
-Hydroxyphenyl)propionate AO-III:
Tetrakis-[methylene-3-(3',5'-di-te
rt-Butyl-4'-hydroxy-phenyl)propionate-methane AO-IV: 1,3,5-trimethyl-
2,4,6-tris(3,5-di-tert-butyl-
4-hydroxybenzyl)benzene

AO-V: 2,6-di-tert-butyl-4-methylphenol AO-VI: Tris(nonylphenyl)phosphite

[0041]

[Example 1 and Comparative Example 1 to Example 4 and Comparative Example 4] The stabilizer shown in Table 1 (A
Predetermined amounts of each of O-I to AO-V were added, the solvent was removed by steam stripping, and after dehydration, the mixture was subsequently dried using a hot roll (110°C). After drying, the phosphorus compound AO-VI shown in Table 1 was added on a hot roll to produce block copolymer samples of the present invention and comparative examples.

The obtained polymer was a block copolymer with a styrene content of 30% by weight and an MI(G) of 6 g/10 min. Lab plastomill kneading tests were conducted on these samples. As a result, the gelation peak (torque peak) times obtained are shown in Table 1. In the Examples and Comparative Examples, it can be seen that block copolymers in which specific phenolic compounds defined in the present invention are combined have a high gelation suppressing effect. Similarly, for Example 2 and Comparative Example 2, Example 3 and Comparative Example 3, and Example 4 and Comparative Example 4, it can be seen that the block copolymer of the present invention has a high gelation suppressing effect.

[0043]

[Examples 5 and 6 and Comparative Examples 5 to 7] Using the same formulation as Examples 1 to 4 and Comparative Examples 1 to 4, predetermined amounts of the phenol stabilizer and phosphorus stabilizer shown in Table 2 were blended, A block copolymer of the present invention was produced. A heating test was also conducted on these samples and the sample of Example 1. A portion of the sample (5 parts) was packed in a cylindrical glass sample bottle with an internal volume of 30 cc, and the top was covered with aluminum foil, and then placed in a gear oven (GPHH-100 model manufactured by Tabai Espec) for 18 hours.
The sample was allowed to stand at 0° C., and the color change over time of the sample after heating was observed and the toluene insoluble content was measured.

[0044] As a result, it was found that the block copolymer combined with the specific phenolic compound specified in the present invention has a good balance between discoloration resistance upon heating and gel suppression.

[0045]

[Table 1]

(Note 1) The amount of each stabilizer is the proportion (parts by weight) based on 100 parts by weight of the block copolymer.
shows. (Note 2) Labo Plastomill Kneading Conditions Kneader: Toyo Seiki Co., Ltd. LPM-2500-200 (
Mixer-B-75) 1. Condition I Sample amount: 50g Kneading conditions: 19
After preheating and kneading at 0°C for 3 minutes at 10 rpm, increase the rotation speed to 120 rpm and measure 2. Condition II Kneading was carried out in the same manner as Condition I under a nitrogen atmosphere. Gas flow rate: Nitrogen 1L/min

[0047]

[Table 2]

(Note 3) 1. Judgment after heating: ◎...Black (white) or almost no change. ○...Pale yellow to yellow △...Light brown ×...Brown to dark brown 2. Toluene insoluble content (wt%) 1 g of the heated composition was dissolved in 100 g of toluene,
The residue on the wire mesh was dried and discharged as toluene-insoluble matter.

[0049]

Effects of the Invention The block copolymer composition of the present invention has improved physical properties at high temperatures by combining a small amount of a specific phenolic compound with a high synergistic effect that has not been seen before in the combination of stabilizers. It has excellent stability and is highly effective in suppressing the generation of gel-like substances. Therefore, by taking advantage of these characteristics, various applications such as thermoplastic resin modification materials, adhesive materials, asphalt modification materials, footwear materials, electric wire and cable materials, home appliances, industrial parts, and automobile parts. It can be used as a material for household items, toys, etc.

Claims (1)

[Claims] Claim 1: (a) has at least one polymer segment mainly composed of a monoalkenyl aromatic compound and at least one polymer segment mainly composed of a conjugated diene, and has a monoalkenyl aromatic compound content. 5-95% by weight
A block copolymer or a mixture of the block copolymer and a thermoplastic resin and/or rubbery polymer,

...100 parts by weight (b) A stabilizer which is a phenolic compound represented by the following general formula [I], ...0.005 to 0.05 parts by weight [Formula 1] (wherein, R1 and R3 are -CH2 -S-R5 where R5 represents an alkyl group having 1 to 18 carbon atoms. R2 represents a hydrogen atom or a methyl group. R4 represents an alkyl group having 1 to 8 carbon atoms or an alkyl group having 5 to 18 carbon atoms. 12 cycloalkyl group) (c) At least one stabilizer selected from phenolic compounds and/or phosphorus compounds other than the following general formula [I]...0.1 to 2.0 weight A thermostabilized block copolymer composition comprising: