JPH0132857B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a block copolymer resin of a styrene compound and a conjugated diene compound, and more specifically, two kinds of block copolymer resins having different weight average molecular chain lengths (hereinafter referred to as average molecular chain lengths) and ratios of styrene compounds and conjugated diene compounds. This invention relates to a block copolymer resin having excellent transparency, impact resistance, and thermal stability, the main component of which is a block copolymer of a styrene compound and a conjugated diene compound (hereinafter referred to as SB block copolymer). Conventionally, SB block copolymer resins have excellent transparency and impact resistance, are molded by molding methods such as injection and extrusion, and are widely used in various fields. Normally, SB block copolymer resins are produced by polymerizing 50% by weight or more of a styrene compound and a conjugated diene compound in the presence of an organolithium compound in a nonpolar solvent. The resulting SB block copolymer resin had insufficient thermal stability and impact resistance during molding.
Improvements in these physical properties have been desired. One way to improve the impact resistance of such SB block copolymer resins while maintaining their transparency is to increase the amount of conjugated diene compound when producing SB block copolymer resins. There are methods of increasing the ratio of conjugated diene compounds during coalescence. However, obtained by this method
During the molding process, the SB block copolymer
There was a problem that the conjugated diene compound became thermally unstable and caused a gelation phenomenon, resulting in low thermal stability. The present inventors conducted extensive research on improving the thermal stability and impact resistance of these SB block copolymers while maintaining their transparency.
If the content of the conjugated diene compound in the block copolymer is kept below 20%, the thermal stability will be improved, but this alone is not sufficient; , and if a lower molecular weight SB block copolymer is added,
The present invention was completed based on the knowledge that the impact resistance was improved and the problems of conventional SB block copolymers could be solved. That is, the present invention has an average molecular chain length of 600 to 1400.
Å, block copolymer (A) with a styrene compound ratio controlled to 50-70% by weight and an average molecular chain length of 3600-
6000 Å, and a block copolymer (B) with a styrene compound ratio controlled to 80 to 95% by weight, is mixed so that the weight ratio of (A)/(B) is 1 or less. In the present invention, styrene compounds include styrene, α-methylstyrene, vinyltoluene, tert
-Includes vinyl aromatic compounds such as butylstyrene and substituted products thereof. Moreover, butadiene, chloroprene, isoprene, etc. are mentioned as a conjugated diene compound. If the content of the styrene compound in the block copolymer (A) is less than 50% by weight, the transparency of the mixture of (A) and (B) will decrease significantly, and if it exceeds 70% by weight, the impact resistance will be improved. I can't. On the other hand, if the styrene compound content of the block copolymer (B) is less than 80% by weight, the thermal stability will be reduced, and if it exceeds 95% by weight, the transparency will be significantly reduced. In addition, the average molecular chain length of the block copolymer (A) is
Below 600Å, the impact resistance of the mixtures (A) and (B) decreases,
At 1400 Å or more, thermal stability decreases. On the other hand, if the average molecular chain length of the block copolymer (B) is less than 3,600 Å, the impact strength will not be improved, and if it exceeds 6,000 Å, molding becomes difficult. The average molecular chain length of the block copolymers (A) and (B) can be adjusted by a general method of adjusting the amount of the organolithium compound used as a polymerization initiator. The average molecular chain length was measured by gel permeation chromatography (hereinafter referred to as GPC). To explain this specifically, we created a calibration curve between the peak count number and the molecular chain length of monodisperse polystyrene using GPC of monodisperse polystyrene manufactured by Waters, and calculated the peak count number of the GPC pattern of the above sample. It is determined by the method of reading the corresponding molecular chain length from the calibration curve. When mixing block copolymers (A) and (B), the weight ratio of (A)/(B) is preferably 1 or less, preferably
It is 0.8 or less. When it exceeds 1, the transparency of the mixture of (A) and (B), that is, the SB block copolymer, decreases,
In addition, the rigidity decreases and the material becomes extremely soft, which is not preferable. The block copolymer according to the present invention has a general structural formula (A-B) _o or (A-B) _o -A (A is a block of a styrene compound polymer, and B is a conjugated diene polymer). (n represents a positive integer) or the general structural formula described in USP-3639517.

[Formula] or

It is a star-shaped block copolymer represented by the formula [Formula], and the block structure is completely block structure or
As seen in 48546, block A and block B
It may have any so-called tapered block structure containing an AB random copolymer portion in the transition region, but a tapered block structure is particularly advantageous. These block copolymers are generally prepared by using an organolithium compound as an initiator in a non-polar solvent.
Although it can be obtained by copolymerizing a dehydrated and purified styrene compound and a conjugated diene, polymers with various structures described above can be obtained by using different polymerization techniques. Examples of nonpolar solvents include aliphatic hydrocarbons such as pentane, hexane, and heptane, alicyclic hydrocarbons such as cyclohexane, methylcyclohexane, and cyclopentane, and aromatic hydrocarbons such as benzene, toluene, and xylene. Examples of organic lithium compounds used as organic lithium compounds include alkyllithiums such as n-butyllithium and sec-butyllithium, butadiene oligomer dilithium, α-methylstyrene tetramer dilithium, etc., but sec-butyllithium is particularly effective. It is. First, a polymer with a tapered block structure, which is considered to be the most preferable in the present invention, is prepared by adding a dehydrated nonpolar solvent and a predetermined amount of an organic lithium compound as an initiator to an autoclave, and then adding a predetermined amount of dehydrated styrene. It is produced by adding a compound to form a block of a styrene compound, and then simultaneously adding the remaining styrene compound and a conjugated diene to connect the tapered block of the conjugated diene and the styrene compound. Ru. Furthermore, a polymer having a completely block structure can be obtained by, for example, using the above production method, by first polymerizing only the conjugated diene without adding the styrene compound and the conjugated diene at the same time, and then polymerizing only the styrene compound. You can get it by twisting it. Furthermore, a polymer with a star-shaped block structure can be obtained by first forming a styrene compound block, then a conjugated diene block, and then adding a polyfunctional coupling agent (for example, CHBr ₃ , SiCl _{4 ,} etc.).
It can be produced by reaction. Although the method and order of mixing the block copolymers (A) and (B) within a limited range and removing the solvent may be carried out in any manner, it is important to uniformly mix the polymer solution of each polymer. The most preferred method is to remove the solvent after the reaction. The block copolymer resin composition thus obtained is processed into various molded products by injection molding, or into sheets or films by extrusion molding. In addition, since the impact resistance and thermal stability are significantly improved, it can be used as an impact modifier for polystyrene, and also in fields such as high-temperature, high-speed molding in harsh thermal environments. The present invention will be specifically explained below with reference to Examples. Example 1 Dehydrated and purified benzene 80 was placed in a 100 autoclave, and sec-butyl lithium 440 was added to it.
mmol was added and the temperature was kept at 40°C. Next, the styrene monomer for the first stage of the polymerization reaction (hereinafter referred to as SM-
1) was added to complete the polymerization.
Butadiene for the second stage of the polymerization reaction (hereinafter referred to as
Bd-2) and styrene monomer (hereinafter abbreviated as SM-2) were added at once in a mixed state of 9 kg and 6.6 kg, respectively, to complete the polymerization. Thereafter, a small amount of alcohol was added to the polymerization solution to stop the polymerization, and a polymerization solution of block copolymer (A) was obtained. This sample was designated as copolymer (A-1). The copolymer (A-1) has a structure AB/A (A is a styrene block, B is a butadiene block, and B/A indicates that the boundary between both blocks is a tapered structure). Furthermore, 110 mmol of sec-butyllithium, SM-1
A polymerization solution of block copolymer (B) was obtained in the same manner as the production method of block copolymer (A) except that Bd-2 was 6.8 kg, Bd-2 was 3 kg, and SM-2 was 10.2 kg. It was referred to as a polymer (B-1). Copolymer (B-1) has the same polymer structure as copolymer (A-1). After mixing and stirring 50% of the polymerization solution of copolymer (A-1) and 100% of the polymerization solution of copolymer (B-1), the mixture was separated into crumbs by steam stripping and dried in a hot air dryer. Dry. Next, 0.5 parts by weight of 2,6-di-tert-butyl-4-methylphenol, 0.3 parts by weight of trisnonyl phenyl phosphorite, and 0.2 parts by weight of stearic acid were added to the dried crumbs, and then pelletized using an extruder. did. The physical properties of this pellet were measured and the results are shown in Table 1. Examples 2, 3 and Comparative Examples 1 to 4 SM-1, Bd-2, SM-2 and initiators are shown in Table 1.
A block copolymer (A) was obtained in the same manner as in Example 1 except that the proportions shown in
-2) and (A-3). Separately, a block copolymer (A) was obtained in the same manner as in Example 1, except that SM-1, Bd-2, SM-2 and the initiator were used in the proportions shown in Table 1.
4) to (A-7). (A-2) and (A-3) are Examples 2 and 3, and (A-4) to (A-7) are sequentially Comparative Example 1.
to 4 were mixed with the block copolymer (B-1) in the proportions shown in Table 1, pellets were prepared in the same manner as in Example 1, and their physical properties were measured and shown in Table 1. In addition, in the table below, the physical properties were measured by the following methods. Haze: A 2 mm thick plate was molded at 200° C. using an injection molding machine and measured according to the method of ASTM-D-1003. Falling weight strength: 3mm thick at 200℃ using an injection molding machine, 4
A cm x 4 cm plate is formed, and in an atmosphere of 20°C, a weight with a radius of 5 m/mφ at the tip is dropped at different weights and heights, and the highest height without breakage is determined by weight x height. It was displayed in Thermal stability...Using an injection molding machine, plates with a thickness of 3 mm were continuously molded at 250℃, and the surface gloss of the 1st and 20th shots was measured, and the difference in gloss reduction (△
G) was measured.

[Table] Examples 4, 5 and Comparative Examples 5 to 8 SM-1, Bd-2, SM-2 and initiators are shown in Table 2.
A block copolymer (B) was obtained in the same manner as in Example 1 except that the proportions shown in
-2) and (B-3). Separately, a block copolymer (B) was obtained in the same manner as in Example 1, except that SM-1, Bd-2, SM-2 and the initiator were used in the proportions shown in Table 2.
4) to (B-7). (B-2) and (B-3) in Examples 4 and 5, respectively
(B-4) to (B-7) were sequentially used as Comparative Examples 5 to 8, mixed with the block copolymer (A-1) in the proportions shown in Table 2, and pelletized in the same manner as in Example 1. The physical properties were measured and shown in Table 2. Example 6 and Comparative Example 9 Pellets were prepared in the same manner as in Example 1, except that 30% of the polymerization liquid of block copolymer (A-1) and 90% of polymerization liquid of block copolymer (B-1) were mixed. was prepared, its physical properties were measured, and the results are shown in Table 2 as Example 6. Separately, the amount of polymerization liquid of block copolymer (A-1) is 90
Polymerization liquid volume of block copolymer (B-1) and block copolymer (B-1) 60
Pellets were made in the same manner as in Example 1 except that the following were mixed, and the physical properties of the pellets were measured and shown in Table 2 as Comparative Example 9. Example 7 In the polymerization apparatus of Example 1, dehydrated and purified benzene 80 was charged, and sec-80 was added as an initiator.
Added 120 mmol of butyllithium, then added 8.5 kg of purified styrene monomer, and heated to 40°C.
Polymerization was completed at . Then 3Kg of butadiene
After reacting at 60°C for 1 hour, the remaining styrene monomer (8.5 kg) was added and polymerized. A small amount of encore was added to the obtained polymerization solution to stop the polymerization, and a block copolymer (B) having a complete block structure was obtained. This polymerization solution was mixed with the polymerization solution of (A-1) in the proportions shown in Table 2, pellets were prepared in the same manner as in Example 1, and the physical properties of the pellets were measured and are shown in Table 2. Example 8 In the apparatus of Example 1, dehydrated and purified benzene 80 was charged, 360 mmol of sec-butyllithium was added as an initiator, and then 17 kg of purified styrene monomer was charged and polymerized. , 3 kg of butadiene was added, and the mixture was reacted at 60°C for 1 hour. Next, 500 cc of a benzene solution containing 100 mmol of silicon tetrachloride was added, and after stirring at 60°C for 1 hour, a small amount of alcohol was added to stop the polymerization, resulting in a copolymer with a star-shaped block structure.
I got (B). This polymerization solution was mixed with polymerization solution (A-1) in the proportions shown in Table 2, pellets were prepared in the same manner as in Example 1, and the physical properties of the pellets were measured and shown in Table 2.

【table】

Claims (1)

[Scope of Claims] 1 (A) A block copolymer of a styrene compound and a conjugated diene compound having a weight average molecular chain length of 600 to 1400 Å and a styrene compound content of 50 to 70% by weight;
and (B) a block copolymer of a styrene compound and a conjugated diene compound with a weight average molecular chain length of 3600 to 6000 Å and a styrene compound content of 80 to 95% by weight; A block copolymer resin of a styrene compound and a conjugated diene compound in which the weight ratio of B) is 1 or less.