JP2847521B2 - Improved polybutadiene rubber - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a novel polybutadiene, and particularly to the improvement of properties such as impact resistance, gloss and rigidity of a resinous polymer such as a styrene resin and a polymethyl methacrylate resin. To a novel polybutadiene suitable for

[Conventional technology]

In recent years, rubber-modified styrenic resins, that is, impact-resistant styrenic resins, have been developed for use in housings and parts of home electrical appliances, office equipment parts, daily miscellaneous goods and toys with the development of their manufacturing technology. It has been spreading to various uses such as. Against this background, there has recently been a demand for better physical properties for impact-resistant styrenic resins, especially advanced balance that balances impact resistance, rigidity, and appearance such as gloss. It has become something.

As is well known, an improvement in impact resistance can be achieved by increasing the content of a rubbery polymer.However, a styrene-based resin having an increased amount of a rubbery polymer has an improved impact resistance, but has a higher rigidity. Significant reduction and gloss reduction. On the other hand, rigidity and gloss can be improved by reducing the content of the rubber-like polymer or by making the particles of the rubber-like polymer dispersed in the resin finer, but the impact resistance is reduced. Is remarkable.

Furthermore, in recent years, the impact-resistant styrene-based resin has been attracting attention in the application field of ABS resin (acrylonitrile-butadiene-styrene resin), but the biggest problem is that
This is inferior in glossiness of the impact-resistant styrenic resin.

Therefore, recently, in order to improve the gloss, a method of controlling the rubber particle diameter to a small value of, for example, 1.7 μm or less has been adopted, but at present, the impact strength is poor and it is difficult to withstand practical use.

As described above, since impact resistance, gloss, and rigidity are properties that are contradictory, it is difficult to maintain a high gloss and rigidity and obtain a styrene-based resin having excellent impact resistance.

Conventionally, as methods for improving impact-resistant styrenic resins, a solution viscosity is specified (JP-A-58-4934), and a relationship between solution viscosity and Mooney viscosity is specified (JP-A-53-44188).
Japanese Patent Application Laid-Open No. 60-250021), specification of the molecular weight distribution (Japanese Patent Application Laid-Open No. 54-15912), specification of the relationship between the solution viscosity and the tensile modulus and swelling degree of the crosslinked organic peroxide (Japanese Patent Application Laid-Open No. )
Such methods have been proposed.

In addition, the present inventors have defined butadiene monomer with an organolithium-based catalyst that specifies the specific relationship among Mooney viscosity (ML), solution viscosity (SV), vinyl content (1,4 cis content), and ML-SV. An impact-resistant styrenic resin using polybutadiene in which a terminal lithium active polymer obtained by polymerization is bonded with a polyfunctional coupling agent has been developed (JP-A-55-75413, JP-A-59-217712). JP-A-61-148213, JP-A-63-72711).

However, these polybutadienes are specifically obtained using an organic monolithium compound as an organolithium catalyst, and a polybutadiene rubber having a low elastic modulus as in the present invention has not been obtained.

[Problems to be solved by the invention]

However, in these methods, it is not always satisfactory to improve the balance among gloss, impact resistance and rigidity.

Further, in Japanese Patent Application Laid-Open No. 60-250021, an impact-resistant styrene resin having excellent impact resistance and rigidity is obtained by using a specific rubbery polymer having a low tensile modulus as a toughening agent. It is stated that it can be obtained.

[Means for solving the problem]

In order to develop a rubber-like polymer for obtaining an impact-resistant styrenic resin having an excellent balance of impact resistance, rigidity, and gloss, the present inventors have specifically developed the elastic modulus of the rubber-like polymer. The research was repeated about the rubber with low.

As a result, it has been found that a resin having excellent impact strength and rigidity and good gloss can be obtained in a region where the elastic modulus of the rubbery polymer is much lower than that of conventional rubber, and the present invention has been completed.

That is, the present invention provides an organic lithium catalyst comprising a reaction product containing a polyvinyl aromatic compound and an organic monolithium compound having a molar ratio of polyvinyl aromatic compound / organic monolithium compound in the range of 0.1 to 0.3, butadiene monomer. Is a polybutadiene obtained by polymerizing the obtained lithium-terminated active polymer with a polyfunctional treating agent, wherein (a) Mooney viscosity is 30 to 80, and (b) 5% by weight styrene measured at 25 ° C. Solution viscosity (SV)
Is 20 to 60 centipoise, (c) the 1,2-vinyl bond content is 10 to 40% by weight, (d) the organic peroxide crosslinked product of the polybutadiene crosslinked under the specific conditions described below, A polybutadiene having an elastic modulus (E) measured under conditions of 10 to 18 kg / cm ² is provided.

The polybutadiene of the present invention is a rubber polymer suitable for improving an impact-resistant styrene resin.

The polybutadiene of the present invention is characterized by having an extremely low elastic modulus as compared with polybutadiene using a commercially available organolithium catalyst.

 Hereinafter, the present invention will be described in more detail.

The specific polybutadiene of the present invention is a specific molar ratio using an organolithium catalyst consisting of a reaction product containing an organic monolithium compound and a polyvinyl aromatic compound.
It can be obtained by solution polymerization.

The polybutadiene of the present invention has a 1,2-vinyl bond content of 1
It is 0 to 40% by weight, preferably 10 to 25% by weight.
If it is out of this range, the resulting resin will have insufficient impact resistance when used for impact-resistant styrenic resins.

The method for producing the polybutadiene having such a specific microstructure may be any conventionally known method as long as the method has the above-mentioned structure, but specific methods include, for example, dimethyl ether, Examples of the method include polymerization in which a polar compound such as an ether such as diethyl ether or tetrahydrofuran; a thioether such as dimethyl sulfide or diethyl sulfide; or an amine such as dimethyl ethyl amine or triethyl amine is added.

The vinyl bond may be uniform in the molecular chain, may gradually decrease along the molecular chain as shown in JP-B-48-875, or may be bonded in a block form. It is sufficient if the content is 10 to 40% by weight as a whole.

The polybutadiene of the present invention has a 1,2-vinyl bond content of 10
-40% by weight, the content of cis-1,4-linkage is 20-40% by weight, and the content of trans-1,4-linkage is 30-60%.
% By weight.

The polybutadiene rubber of the present invention has a Mooney viscosity (ML
_{1 + 4} ) is 30 to 80, and the 5% by weight styrene solution viscosity (SV) measured at 25 ° C. needs to be 20 to 60 centipoise (cps).

If the Mooney viscosity is less than 30, when used for impact-resistant polystyrene resin, the resulting resin has poor impact resistance,
When it is higher than 80, the appearance characteristics are inferior.

Also, if the viscosity of the 5% by weight styrene solution is less than 20 cps,
When used as an impact-resistant polystyrene resin, the resulting resin has poor impact resistance. If it is higher than 60 cps, rigidity and appearance characteristics are reduced.

Further, the elastic modulus (E) of the organic peroxide crosslinked product of polybutadiene in the present invention needs to be 10 to 18 kg / cm ² .

When the elastic modulus is less than 10 kg / cm ² or more than 18 kg / cm ² , when used as an impact-resistant polystyrene resin, the resulting resin is inferior in impact resistance.

Next, a method for measuring characteristics of the polybutadiene used in the present invention will be described.

Mooney viscosity is ML _{1 + 4} (100 ° C).

The 5% by weight styrene solution viscosity was measured at 25 ° C. using a Cannon-Fenske viscometer.

The 1,2-vinyl bond content was determined using a Morero method [La chimica EL'industria, 41,758 (195) using an infrared spectrophotometer.
9)].

The elastic modulus in the present invention refers to a dynamic elastic modulus of a crosslinked organic peroxide prepared by crosslinking under a specific condition and measured under a specific condition using a viscoelasticity measuring device.

Specific conditions are described below; 1) First, preparation of a crosslinked product with an organic peroxide is performed by the following method.

55 g of polybutadiene rubber and 0.055 g (0.1 parts by weight per 100 parts by weight of rubber) of organic peroxide dicumyl peroxide are kneaded in the following apparatus.

Kneading device: Labo Plast Mill (Model LPM-2500-200) manufactured by Toyo Seiki Seisakusho Kneading conditions: Pre-mixing (sample input); 50 ° C, 10 rotations, 3
0 seconds, (b) kneading; 50 ° C., 50 rotations, 2 minutes, the kneaded material was compression molded at a temperature of 160 ° C. under a pressure of 200 kg / cm ² for 18 minutes to form a sheet of a crosslinked organic peroxide. obtain.

2) Next, a test piece is cut from the sheet molded product of the organic peroxide crosslinked product, and the dynamic elastic modulus is measured by a viscoelasticity measuring device.

(Measurement conditions) (a) Measurement model: VESF-III type manufactured by Iwamoto Seisakusho, Ltd. (b) Measurement method: elongation deformation (constant initial load), (c) Measurement frequency: 100 Hz, (d) Initial load: 200 g (E) Vibration amplitude: 300μ, (f) Measurement temperature: 25 ° C, (g) Sample dimensions: (width) 5mm x (thickness) 2mm x (length) 30mm, The polybutadiene rubber of the present invention is as described above. As described above, the organic peroxide crosslinked product has specificity in that its elastic modulus is lower than that of a conventional general rubber.

In order to produce such polybutadiene, some contrivance is required.

As a specific method, a reaction product containing at least a polyvinyl aromatic compound and an organic monolithium compound having a molar ratio of polyvinyl aromatic compound / organic monolithium compound in the range of 0.1 to 0.3 is used as an organolithium catalyst. , A butadiene monomer is polymerized, and after the polymerization is substantially completed, the resulting lithium-terminated active polymer is bound with a polyfunctional treating agent.

In addition, when the butadiene monomer is polymerized, it is preferable to carry out the reaction by a badge method, and furthermore, the above catalyst and butadiene are separately added and reacted.

The polyvinyl aromatic compound referred to herein includes, for example, divinylbenzene, 1,2,4-trivinylbenzene, 1,3-divinylnaphthalene, 1,3,5-trivinylnaphthalene, 2,4-
Examples thereof include divinylbiphenyl and 3,5,4-trivinylphenyl, and divinylbenzene is particularly preferred. This divinylbenzene has o-, m- and p- isomers,
Even if divinylbenzene as a mixture of these isomers is used, the effect is sufficiently exhibited.

On the other hand, examples of the polyfunctional treatment agent include silane compounds such as trichloromethylsilane, dimethyldichlorosilane, and silicon tetrachloride (J. polym.sci, A-1, 3, 9
3 (1965)], diester carbonates such as diethyl carbonate (JP-B-54-8716), divinyl aromatic compounds such as divinylbenzene (JP-A-51-34290), halogen compounds such as carbon tetrachloride, Known compounds such as a tin compound such as tetrachlorotin can be used. These may be used alone or in combination of two or more.

Further, triethylamine, tri-n-butylamine,
Polar substances such as hexamethylphosphoramide, diethyl ether and tetrahydrofuran may be added to the polymerization system.

The polybutadiene of the present invention is obtained by polymerizing a butadiene monomer with the above-mentioned specific organolithium catalyst, and binding the resulting terminal lithium active polymer with a polyfunctional treating agent. The content of the component is preferably 20% by weight or more in the whole polymer, and 50 to 95% by weight.
Is more preferable.

The amount of the binding polymer component is adjusted by the ratio of the amount of the polyfunctional treating agent to the amount of the organolithium catalyst.

Regarding the molecular weight distribution of the polybutadiene thus obtained, the ratio (Mw / Mn) of the weight average molecular weight (Mw) to the number average molecular weight (Mn) measured by GPC (gel permeation chromatography) is usually 2.2 to It is in the range of 4.2 and has a polymodal shape.

As an example of producing polybutadiene used in the present invention, cyclohexane is charged into an autoclave, and tetrahydrofuran is added in an amount of 50 ppm to 4000 ppm based on cyclohexane. Next, 30-70% of the total use amount of the butadiene monomer was added, and the temperature was raised to 60-80 ° C. Then, the total use amount of the reaction-producing catalyst separately prepared from n-butyllithium, butadiene monomer, and divinylbenzene (n -0.25 to 0.6 based on 100 parts of butadiene monomer used as butyllithium equivalent
(0 parts) is added to initiate the reaction. After the completion of the monomer reaction, the remaining monomer (70 to 30% of the total amount of butadiene monomer) and the remaining catalyst (90 to 50% of the total catalyst used) are added, and the reaction is continued.

After completion of the reaction, 0.05 to 0.15 parts of silicon tetrachloride was added as a polyfunctional treatment agent, and after coupling treatment,
A stabilizer is added and the solvent is separated to obtain the desired polybutadiene.

〔Example〕

Hereinafter, some examples will be described to show specific embodiments of the present invention. However, these examples are intended to more specifically explain the gist of the present invention and do not limit the present invention.

(Example 1) Polybutadiene was obtained by the method shown below under the charging amounts and conditions shown in Table 1.

After washing and drying the autoclave having an internal volume of 10 and purging with nitrogen, cyclohexane and tetrahydrofuran which had been purified and dried in advance were added, and then the dried initial butadiene monomer was added. Next, this solution was heated to the reaction start temperature, the initial catalyst was added, and the reaction was started. After completion of the reaction, subsequently, an added catalyst and an added butadiene monomer were added, and the reaction was restarted. After completion of the reaction, silicon tetrachloride was added and the reaction was carried out for 20 minutes. After the completion of the reaction, 2,6-di-t-4-methylphenol (BHT) as a stabilizer was added to the obtained polymer solution in an amount of 0.5 part by weight based on 100 parts by weight of the polymer, and the solvent was removed by heating using a two-roll mill.

(Examples 1 to 6 and Comparative Examples 1 to 6) In the same manner as in Example 1, polybutadienes of Examples 1 to 6 and Comparative Examples 1 to 6 were obtained under the conditions shown in Table 1.

Table-A shows a method for preparing the organolithium substrate catalyst used in the production of this polybutadiene.

The organolithium substrate catalysts A, B, and C were reacted and prepared under the preparation ratios and conditions shown in Table-A, respectively.

As divinylbenzene, commercially available divinylbenzene was used. This product was a mixture containing 57% of the divinylbenzene isomer, the balance being ethylvinylbenzene, diethylbenzene.

(Reference Example) <Production of Impact-Resistant Styrene-Based Resin> Using the respective polybutadienes obtained in Examples 1 to 6 and Comparative Examples 1 to 6, an impact-resistant styrene-based resin was prepared by a bulk polymerization method described below. Obtained.

28 to 42 g of polybutadiene, 672 to 658 g of styrene, 14 g of mineral oil, and 2.1 g of a stabilizer (Irganox 1076) were uniformly dissolved in respective proportions.

This was transferred to an 11-separable flask with a stirrer,
3 hours at 120 ° C, 2 hours at 135 ° C, 2 hours at 150 ° C, 170 ° C
For 2 hours. After further heating at 230 ° C. for 30 minutes, unreacted substances were removed under reduced pressure, and the obtained polymer was pelletized by an extruder.

Izod impact strength was measured according to JIS K-7110 using a 3.2 mm thick test piece prepared by compression molding.

Gloss was measured according to ASTM D-638 using dumbbell specimens injection-molded and according to ASTM D-523, and the gloss (incident angle 60 °) of the gate portion and the end gate portion was measured and averaged.

Flexural modulus is 3.2m thickness created by compression molding
It measured according to ASTM D-790 using the test piece of m.

The obtained results are referred to in Reference Examples 1 to 6 and Reference Comparative Examples 1 to
6 is shown.

As is clear from the results of Reference Examples 1 to 6, when the impact-resistant polystyrene resin is polymerized using the polybutadiene of the present invention, a resin having excellent gloss and rigidity and simultaneously improved impact resistance is obtained. I understood that.

On the other hand, as is clear from the results of Reference Comparative Examples 1 to 6, when an impact-resistant polystyrene resin was obtained using a polybutadiene other than the present invention, either the glossiness or the impact resistance was reduced. Is inferior.

[Effect of the Invention] When the specific polybutadiene of the present invention is used for producing a styrene resin, the impact resistance can be improved without impairing the appearance and rigidity of the styrene resin. It is also used to improve the impact resistance of acrylic resin.

Furthermore, if the polybutadiene of the present invention is used instead of the rubber conventionally used for tires, workability and bending resistance can be improved.

As described above, the polybutadiene of the present invention is excellent as a resin modifier and also exhibits excellent effects as a rubber for tires.

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Claims (1)

(57) [Claims] An organolithium catalyst comprising a reaction product containing a polyvinyl aromatic compound and an organic monolithium compound having a molar ratio of polyvinyl aromatic compound / organic monolithium compound in the range of 0.1 to 0.3. A polybutadiene obtained by polymerizing and binding the obtained terminal lithium active polymer with a polyfunctional treating agent, wherein (a) Mooney viscosity is 30 to 80, and (b) 5% by weight styrene solution measured at 25 ° C. Viscosity (SV)
Is 20 to 60 centipoise, (c) the content of 1,2-vinyl bond is 10 to 40% by weight, and (d) the elastic modulus of the organic peroxide crosslinked product is 10 to 18.
kg / cm ² , polybutadiene.