JP2630955B2 - Butadiene-styrene block copolymer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention improves the impact resistance in addition to a resinous polymer such as a styrene resin or a polymethyl methacrylate resin, and forms a molded article itself. And a novel butadiene-styrene block copolymer.

[Prior art] Styrene resins are widely used in various applications because of their excellent rigidity, transparency, gloss, etc., and their excellent moldability, but their rubbery polymers have been modified due to their poor impact resistance. It is added to styrenic resins as filler. As a method,
There are a method of mechanically blending a rubber-like polymer with a polystyrene resin, and a method of bulk-polymerizing a styrene solution of the rubber-like polymer or a method of bulk-suspension polymerization.
Particularly, the addition by polymerization is widely practiced industrially as an impact-resistant styrenic resin and used as a household electrical product because the resulting polymer has excellent physical properties.

[Problems to be Solved by the Invention] However, the addition of the rubbery polymer to the above-mentioned impact-resistant styrenic resin necessitates a reduction in appearance properties such as gloss and transparency.

In recent years, impact-resistant styrene-based resins with gloss and transparency that can be used in a wide variety of applications, including food packaging such as frozen desserts and food containers such as beverage cups, have been strong due to the expansion of market applications. Requested.

One method for improving the appearance characteristics of impact-resistant styrenic resins is to add a block copolymer of a monovinyl aromatic hydrocarbon and a conjugated diolefin hydrocarbon to a rubbery polymer added as an impact modifier. A method using a polymer is known.

For example, British Patent No. 1045421 discloses that at least one of a monovinyl aromatic hydrocarbon polymer block (referred to as A) and a conjugated diolefin polymer block (referred to as B) are used as rubbery polymers. Using 1 to 20 parts by weight of a block copolymer composed of the above, for example, AB type or ABA type, and copolymerizing a mixture with 99 to 80 parts by weight of a monovinyl aromatic hydrocarbon monomer Discloses a method for producing an impact-resistant styrene polymer. An impact-resistant styrene polymer using such a block copolymer as a rubbery polymer has a better surface gloss and superior appearance characteristics compared to the case where polybutadiene is used, but its impact resistance is high. Is not always enough.

Japanese Patent Publication No. 48-18594 discloses a block copolymer of 30 to 45% by weight of a monovinyl aromatic hydrocarbon and 1,3-butadiene having an intrinsic viscosity and a weight-average molecular weight (hereinafter referred to as "weight average molecular weight").
Abbreviated as M _W), the number-average molecular weight (hereinafter abbreviated as M _N),
Although a method using Mooney viscosity and 1,2 vinyl content each limited to a specific range is shown, satisfactory results have not been obtained.

In addition to the above reforming method, Japanese Patent Publication No. 60-57443 discloses
The use of various rubbery polymers, particularly butadiene-styrene block copolymers or butadiene-styrene tapered block copolymers, in which the particle size of the dispersed soft component phase is limited to 1 μm or less, to improve the transparency of thin layers having improved transparency. Impact styrenic resins are disclosed. However, the rubber-like polymer used here is more likely to be powdery than the rubber-like polymer generally used, and it is difficult to form a veil. Therefore, when manufacturing on an industrial scale, techniques are required for the drying and packaging processes, and as a result, there remains a problem in terms of cost.

[Means and Actions for Solving the Problems] Under such circumstances, the present inventors can impart impact resistance without impairing the appearance characteristics of the styrenic resin, and hardly become powder at the time of production, A detailed study was conducted on rubbery polymers that are easy to package. As a result, it has been found that a very limited butadiene-styrene block copolymer can achieve this object, and the present invention has been completed.

That is, the present invention relates to (a) the molecular weight distribution curve of the block styrene moiety having a peak molecular weight of 30,000 or more, and
The content ratio of the molecular weight part of 1/3 or less is 25 to 50 mol% of the whole block styrene part. (B) The total styrene content in the copolymer is 15 to 50% by weight. 69-79% by weight of styrene content (d) The molecular weight at the peak of the molecular weight distribution curve of the copolymer is
Butadiene-styrene block copolymer characterized by having a molecular weight of 200,000 to 650,000.

 Hereinafter, the present invention will be described in detail.

The butadiene-styrene block copolymer (hereinafter, abbreviated as block copolymer) of the present invention is a rubbery polymer having a limited structure.

Block copolymers of the present invention is the molecular weight of the peak portion of the molecular weight distribution curve (hereinafter abbreviated as M _P) is 200,000～650,000,
Preferably it is 250,000-550,000. Further, the block copolymer The range of 1.1 to 2.0 is preferred.

When M _P of the block copolymer is less than 200,000, a sufficient impact resistance of the resin when added to high impact styrene resin, the M _P exceeds 650,000, the impact on an industrial scale When producing a styrenic resin, the dissolution step requires a long time, and the solution has high viscosity and high transfer energy, which is not preferable.

Further, (hereinafter abbreviated as SM _P) molecular weight of the peak portion of the molecular weight distribution curve of the block styrene portion of the block copolymer of the present invention is limited to 30,000. If SM _P is less than 30,000, during the production of the impact-resistant styrenic resin, any range of particle size of the block copolymer, in particular hardly controlled in a small area, the required impact resistant styrenic resin obtained Absent. When the block copolymer of the present invention is used as a rubbery polymer component of an impact-resistant styrenic resin, it is easy to control the rubber particles to a small particle size, and particularly a small rubber having a diameter of 0.1 to 1.0 μm. A resin having particles can be obtained.

Further, the content of molecular weight of less SM _P / 3 is a block copolymer of the present invention is limited to the range of 25~50mol%. If the amount is less than 25 mol%, the molded product of the block copolymer tends to be in a powder form, and the moldability is poor. This means that when the block copolymer is manufactured on an industrial scale, the scattering of the block copolymer powder in the drying step increases, the risk of static ignition at high temperatures increases, and the operation control of the device becomes difficult. It becomes a big problem such as difficulty. In addition, bale-like products obtained industrially are easily broken,
When handling products, the workability is poor, which is not preferable. Also
If it is more than 50 mol%, the gloss of the resin obtained when used as an impact-resistant polystyrene resin is reduced.

Next, the total styrene content in the block copolymer of the present invention is in the range of 15 to 50% by weight. When the total styrene content is less than 15% by weight, the appearance characteristics of the resulting impact-resistant styrenic resin are poor, and when it is more than 50% by weight, the impact resistance is poor.

The block styrene content of the block copolymer of the present invention is in the range of 65% by weight or more of the total styrene content, preferably 65% by weight to 90% by weight, more preferably 65% by weight to 80% by weight.
In the range. If the content is less than 65% by weight, the surface gloss of the resulting impact-resistant styrene resin is undesirably reduced. However, in the present invention, the range of 69 to 79% by weight is employed to avoid duplication with the prior application (Japanese Patent Application No. 61-191595).

As described so far, the block copolymer of the present invention is the molecular weight, has a styrene content or the like is limited structure, the value of M _P / SM _P is preferably in the range of 4-10.

The solution viscosity (5% by weight styrene solution viscosity at 25 ° C.) is preferably 15 to 60 centipoise (cps).

Next, a method for measuring the butadiene-styrene block copolymer of the present invention and the constituent components will be described.

The molecular weight is a value measured and calculated by GPC (gel permeation chromatography).

GPC measurement conditions Measurement model Waters M-6000 type Solvent THF (tetrahydrofuran) column DuPont Solvax (ZORBAX) PSM1000S 2 pieces Solvax (ZORBAX) PSM 60S 1 piece Column temperature 35 ° C Pumping rate 0.7ml / min Liquid sending pressure 800 psi Sample concentration 0.1 wt% Sample liquid volume 0.1 ml Detector Differential refractometer Standard polystyrene (Waters); monodisperse polystyrene molecular weight 1,140,470,110,35,000,
The GPC of 8500,2350) were measured to obtain the retention capacity of the peak position (hereinafter abbreviated as V _R), to construct a correlation curve between the molecular weight and V _R.

Measuring the GPC of M _P block copolymer, obtained from the correlation curve from V _R of the peak position.

M _W, in the same manner as M _N M _P was measured by GPC of the sample is calculated by dividing a standard method.

Dividing a standard method is a general method for determining the average molecular weight and a content thereof molecular weight by dividing the GPC chart for each unit V _R, for example, "gel chromatography <Fundamentals>" (Tsuguo Takeuchi,
(Sadao Mori, Kodansha) 117-123.
In this case, as the divided width of the V _R is narrow, since the accuracy is high,
11.67μ the V _R in the present invention (as retention time every 1 second)
It was divided and calculated.

SM _P block copolymer how oxidation decomposed by tert- butyl hydroperoxide osmium tetroxide as a catalyst (LMKOLTHOFF.etal., J.polym.Sci.1,429
(1946)) The styrene polymer block obtained by decomposition according to (1946) was measured in the same manner as by GPC. More specifically, about 0.05 g of a block copolymer sample was dissolved in 10 ml of carbon tetrachloride, and 16 ml of a 70% aqueous solution of tert-butyl hydroperoxide and 4 ml of a 0.05% chloroform solution of osmium tetroxide were added. Decompose under reflux for 15 minutes. After cooling, 200 ml of methanol was added to the solution under stirring to precipitate a polystyrene component, which was separated with a glass filter. The separated polystyrene component is dissolved in THF to obtain a GPC sample.

Content of SM _P / 3 Each V _R from GPC chart for which SM _P was determined
Find the area ratio of the unit. In the case of the present invention, V _R 11.67μ
Calculate the weight percentage of each (W _i), determine the molecular weight of each V _R from the correlation curve (M _i). Mol ratio of each of these _{V R (W i / M i} )
The _{calculated, (W i / M i)} / Σ (W i / M i) mol ratio of the number from the above equation for each V _R is obtained. From this data S
The content ratio of the molecular weight part of M _P / 3 or less is calculated.

Further, the total styrene content of the block copolymer of the present invention was measured by an ordinary method using an ultraviolet spectrophotometer. Similarly,
The block styrene content was determined by measuring the amount of polystyrene component obtained by the above-described decomposition method using tert-butyl hydroperoxide using an ultraviolet spectrophotometer, and expressed as a percentage by weight based on the block copolymer before decomposition.

The block copolymer of the present invention is usually produced in a hydrocarbon solvent using an organolithium catalyst. As the organic lithium metering catalyst, for example, n-propyl lithium, iso-propyl lithium, n-butyl lithium, sec
-Butyllithium, tert-butyllithium, benzyllithium and the like, preferably n-butyllithium,
For example, sec-butyllithium is used. As the hydrocarbon solvent, aliphatic hydrocarbons such as butane, pentane and hexane, alicyclic hydrocarbons such as cyclopentane and cyclohexane, and aromatic hydrocarbons such as benzene, toluene and xylene are used.

The block copolymer of the present invention is a method of polymerizing a monomer mixture of butadiene and styrene at a rate lower than the polymerization rate of the monomer at a set polymerization temperature in a hydrocarbon solvent in which an organolithium catalyst is present. (Special public akiaki
No. 38-2394). That is, polymerization is performed while supplying a monomer mixture having a desired butadiene / styrene composition ratio at a polymerization rate or lower, and then supplying a monomer mixture having a different butadiene / styrene composition ratio at a polymerization rate or lower. Is repeated once or more to produce the block copolymer of the present invention.

Further, a method of adding a polar substance such as triethylamine, tri-n-butylamine, hexamethylphosphoramide, diethyl ether, or THF to a polymerization system containing an organolithium catalyst (Japanese Patent Publication No. 36-15386) may be applied. it can. That is, an organic lithium catalyst and a polymerization system containing a polar substance are polymerized with a monomer mixture having a desired butadiene and styrene composition ratio, and then a monomer having a different butadiene and styrene composition ratio is added and polymerized. By repeating the operation once or more, the block copolymer of the present invention can be obtained. A method based on a combination of these methods is also possible.

As a production example of the block copolymer of the present invention, a mixture of about 15% by weight of butadiene and styrene (20% by weight of styrene) was prepared in cyclohexane using an autoclave,
F is added to cyclohexane at 50 to 1000 ppm. 60-80
After heating to ℃, n-butyllithium was added
0.10 g was added to start the reaction, and after completion of the monomer reaction,
Immediately add styrene and continue the reaction. At this time, the reaction is adjusted so that the maximum temperature of the reaction is 90 to 100 ° C. After the reaction,
The solvent is separated by adding a stabilizer to obtain a target block copolymer.

[Examples] Some examples will be shown below to show specific embodiments of the present invention. However, these are intended to more specifically explain the gist of the present invention and limit the present invention. is not.

Example 1 An autoclave having an internal volume of 10 was washed and dried, and after purging with nitrogen, 3300 g of previously purified and dried cyclohexane and 1.0 g of tetrahydrofuran were added, and then 290 g of dried butadiene was added.
And 105 g of dried styrene. Next, after raising the temperature of the monomer mixture to 77 ° C., n-butyllithium was added.
5.0 g of a 10% by weight cyclohexane solution was added to start the reaction. After the completion of the reaction, the reaction was restarted by adding 105 g of styrene, and the polymer solution obtained after the completion of the reaction was used as a stabilizer.
0.5 parts by weight of 2,6-di-tert-4-methylphenol (BHT) was added to 100 parts by weight of the polymer, and the solvent was removed by heating with a two-roll mill.

Hereinafter, block copolymers of Reference Example 2, Examples 3, 4 and Comparative Examples 1 to 4 were obtained in the same manner as in Example 1 under the conditions shown in Table 1.

Table 2 shows the analytical values of these block copolymers and the evaluation results of the moldability.

_{M P, SM P, M W} , M N, the content of SM _P / 3, analysis of total styrene content, and block styrene content was analyzed by the method described above.

The solution viscosity was measured by dissolving 5 parts by weight of the obtained block copolymer in 95 parts by weight of styrene and measuring the temperature at 25 ° C. using a Canon Fenske viscometer.

In addition, the evaluation of the moldability of the block copolymer into a solid form and the evaluation of powderization were performed under the following conditions.

[Measurement of apparent density of compression molded product and check of appearance] Mold for compression molding 10cm × 10cm × 2cm Compression pressure 150kg / cm ² Compression time 1min Compression temperature 50 ℃ Sample size 250g After pressure molding under the above conditions The sample protruding from the mold was removed, and the volume and weight of the molded product were measured to obtain a value of weight / volume, which was defined as an apparent density. The appearance of the molded product was checked visually and by touch, and evaluated according to the following criteria and evaluated in three stages.

Using each of the rubbery polymers obtained in Example 1, Reference Example 2, Examples 3 and 4, and Comparative Examples 1 to 4, an impact-resistant styrene resin was obtained by a bulk polymerization method described below.

9 to 15 parts by weight of rubbery polymer, 91 to 85 parts by weight of styrene,
2 parts by weight of mineral oil, stabilizer (Irganox 10
76) It was uniformly dissolved at a ratio of 0.3 parts by weight.

This was transferred to a reactor equipped with a stirrer and kept at 120 ° C for 3 hours.
Polymerization was performed at 35 ° C. for 2 hours, at 150 ° C. for 2 hours, and at 170 ° C. for 2 hours.

Thereafter, unreacted substances were removed at 230 ° C. under reduced pressure, and the obtained polymer was pelletized by an extruder.

Izod impact strength is the thickness created by compression molding
It measured according to JIS K-7110 using a 3.2 mm test piece.

The gloss was injection-molded using a 150 mm × 150 mm, 2 mm-thick mold with a single-pin gate, and the gloss of the gate portion and the opposite side of the gate were measured in accordance with JIS K-8741, and the average value was taken.

The obtained results are shown in Reference Examples 1 to 4 and Reference Comparative Examples 1 to 4. As is clear from the results of Example 1, Reference Example 2, Examples 3, 4, and Reference Examples 1 to 4, the block copolymer of the present invention has excellent moldability, and has an impact resistance using the polymer. It was found that when a polystyrene resin was polymerized, a resin having excellent gloss and improved impact resistance was obtained. The transparency was also good. In contrast, Comparative Examples 1 to 4,
As is clear from the results of Reference Comparative Examples 1 to 4, the block copolymers other than the present invention were inferior in either properties of gloss or impact resistance when a moldable or impact-resistant polystyrene resin was obtained. .

[Effect of the Invention] The block copolymer of the present invention is easy to handle and, when added to a styrene resin, can improve impact resistance without impairing the appearance of the styrene resin. It is also used to improve the impact resistance of other resins. In addition to these, if the asphalt is added to asphalt instead of rubber, which has been conventionally used to prevent cracking of asphalt for pavement at low temperature and flow prevention at high temperature, deterioration of workability due to increase in viscosity of asphalt mixture can also be prevented .

As described above, the block copolymer of the present invention exhibits excellent effects as a resin modifier and asphalt modifier.

Claims (1)

(57) [Claims] (1) The molecular weight distribution curve of the block styrene part has a peak molecular weight of 30,000 or more, and the content ratio of the molecular weight part of 1/3 or less of the peak molecular weight is 25 to 25 of the entire block styrene part. (B) The total styrene content in the copolymer is 15 to 50% by weight (c) The block styrene content is 69 to 79% by weight of the total styrene content in the copolymer (d) Molecular weight distribution curve of the copolymer The molecular weight at the peak of
A butadiene-styrene block copolymer having a molecular weight of 200,000 to 650,000.