JPH03188114A - Hydrogenated block copolymer - Google Patents

Abstract

PURPOSE:To prepare the title copolymer which is soft and exhibits excellent low-temp. properties, a high impact resistance, a low compression set, and good mechanical strengths by hydrogenating a copolymer comprising a vinyl arom. polymer block and an isoprene-butadiene copolymer block. CONSTITUTION:The title copolymer, useful for daily-use goods, industrial goods, food containers, packaging materials, etc., comprises a polymer block (pref. having a mol.wt. of 4000-100000) consisting of a vinyl arom. compd., such as styrene, and a hydrogenated isoprene-butadiene copolymer block (having a 1,4-bond content of 65% or higher, a degree of hydrogenation of unsatd. bonds of 30%, and a heat of fusion of crystal of 8kcal/g or lower).

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a hydrogenated block copolymer that is flexible, has excellent low-temperature properties and impact resistance, has low permanent deformation, and has good mechanical strength.

(Prior art) A hydrogenated block copolymer consisting of a conjugated diene and a vinyl aromatic compound has good weather resistance, heat resistance, impact resistance,
It is a highly flexible thermoplastic rubber that exhibits the same strength and elasticity as vulcanized rubber without being vulcanized, so it is widely used in daily goods, automobile parts, light electrical parts, and various industrial products. It is being said.

Such a hydrogenated block copolymer can be obtained by hydrogenating a relufrock copolymer obtained by copolymerization of a conjugated diene and a vinyl aromatic compound. (G) Publication No. 42-4704 , Special Publication Showa 42-893
Publication No. 3, Special Publication No. 6636, Special Publication No. 43-6636, Special Publication No. 48-
3555, JP-A-46-7291, etc.) When using hydrogenated block copolymers for various purposes such as those mentioned above, a method has been proposed in which they are mixed with oil or various thermoplastic resins. has been done. Example Eva Special Public Service 1977
Japanese Patent Publication No. 18739 proposes to improve the low-temperature impact properties of polypropylene by mixing it with polypropylene, Japanese Patent Publication No. 57-56941 proposes to use noryl resin, and Japanese Patent Publication No. 57-56941 proposes to improve the low-temperature impact properties of polypropylene. It is proposed to improve the properties of various engineering plastics by mixing them with other engineering plastics. Conventionally used hydrogenated block copolymers use butadiene and isoprene as conjugated dienes, but when butadiene is used, the low-temperature properties are inferior, and when isoprene is used, the mechanical strength is somewhat low. At present, it has drawbacks and its practical use is extremely limited.

(Problems to be Solved by the Invention) An object of the present invention is to provide a hydrogenated block copolymer that is flexible, has excellent low-temperature properties and impact resistance, has low permanent deformation, and has good mechanical strength.

(Means for Solving the Problems) As a result of various studies, the present inventors have developed a copolymer consisting of a polymer block made of a vinyl aromatic compound and a polymer block made of a mixed monomer of isoprene and butadiene. It was discovered that the objective could be achieved by hydrogenation, and the present invention was completed.

That is, the present invention provides a polymer block (A) consisting of a vinyl aromatic compound and a polymer block (A) consisting of isoprene-butadiene.
, a polymer block (B) in which the amount of 4-bonds is 65% or more and 30% or more of the unsaturated bonds in the chain are hydrogenated, and the heat of crystal fusion of the polymer block (B) is 8ca.
1/g or less. The present invention will be explained in detail below.

Examples of the vinyl aromatic compound used in the present invention include styrene, α-methylstyrene, o-, m- or p-methylstyrene, 1,3-dimethylstyrene, vinylnaphthalene, vinylanthracene, etc.
Styrene or α-methylstyrene is preferably used for boat fishing. These compounds can be used alone or in combination of two or more.

The molecular weight of the polymer block (A) consisting of a vinyl aromatic compound is 4. It is preferable that it is OO0 or more.

If the molecular weight is smaller than this value, the glass transition temperature (Tg) of the aggregate (domain) consisting of this polymer block
(and mechanical properties are also poor, which is not preferable.) There is no upper limit in the strict sense of the molecular weight of the polymer block (A), but from the viewpoint of processability, it is preferably 100,000 or less.

In the present invention, the polymer block (B) consists of a mixed monomer of isoprene and butadiene, and these monomers can be used in the range of isoprene/butadiene = 99/1 to 1/99 (wt%), but the preferred range is is isoprene/butadiene = 90/10 to 65/35 (wt%)
It is.

The molecular weight of the polymer block (B) is 30,000 to 300
, 000 is preferable. If the molecular weight is lower than this range, the effect of improving impact resistance will be low, and if it is higher than this range, processability will deteriorate, which is not preferable.

When polymerization is carried out using a normal anionic polymerization method, 1
．． 4- The amount of bonding is ~90% and the amount of vinyl bonding is ~10
% of the microstructure is obtained. 1,
As a means of reducing the amount of 4-bonds, there is a method of adding a small amount of tetramethylethylene diamine, diethylene glycol dimethyl ether, etc., but in that case, it is necessary to adjust the amount added so that the amount of vinyl bonds is 35% or less.

The hydrogenated block copolymer of the present invention has a polymer block (B
) If the amount of vinyl bonds increases, its low-temperature properties will be impaired, so the amount of 1.4-bonds must be 65% or more.

Polymer block (B) also contains 30 of the unsaturated bonds in the chain.
% or more must be hydrogenated.

If the hydrogenation rate is less than 30%, there are disadvantages in that thermal deterioration tends to occur during melt mixing of the hydrogenated block copolymer and thermoplastic resin, and compatibility deteriorates, and furthermore, when used in various applications, the product It is undesirable because it has the disadvantage of poor weather resistance. The preferred range of hydrogenation rate is 50% or more. The hydrogenation rate referred to here can be calculated by an iodine value measurement method.

The polymer block (B) (hereinafter referred to as the lastomer block) has crystallinity due to hydrogenation of the unsaturated bonds, but the degree of crystallization is The heat of fusion (hereinafter abbreviated as ΔH) is 8 cal/
g or less. If ΔH exceeds this value, the flexibility and low-temperature properties of the obtained hydrogenated block polymer will be impaired, and permanent deformation will increase when deformed, which is not preferable. This heat of crystal fusion can be measured using differential scanning calorimetry.
ning calori-rnetry, D S
(abbreviated as C), and its measurement can be performed, for example, in accordance with the "R Polymer Analysis Handbook" (edited by the Japanese Society of Analytical Chemistry).

The ΔH of this elastomer block is influenced by the copolymerized amount of butadiene, the microstructure of these dienes, the randomness of the isoprene and butadiene chains, the microstructure of the diene, the hydrogenation rate, etc.

For example, completely 1,4-bonded polyisoprene becomes an ethylene-propylene alternating copolymer structure even after complete hydrogenation, resulting in poor quality, but on the other hand, completely 1,4-bonded polybutadiene is completely hydrogenated. Then, it has the same structure as polyethylene without branches, and has extremely high crystallinity. Moreover, crystallinity is generally expressed when about 12 methylenes (CHZ) are bonded in a linear chain. In other words, if three butadiene atoms are linked by 1,4-bonds and a completely hydrogenated chain exists, crystallinity will be observed. Therefore, the elastomer block has a copolymerized amount of butadiene,
By appropriately controlling the microstructure of these dienes, the randomness of the isoprene and butadiene chains, the microstructure of the diene, the hydrogenation rate, etc., ΔH can be reduced to 8 cal/
g or less.

The form of the hydrogenated block copolymer of the present invention is (AB),
A (BA) or (AB) kx, where n represents an integer of 1 to 5, k represents an integer of 2 to 4, and
represents a coupling agent residue.

The weight ratio of the vinyl aromatic compound, isoprene, and butadiene mixture in this hydrogenated block copolymer can be selected depending on the purpose, but is usually 5/95 to 80/2.
The preferable range from the viewpoint of improving flexibility and impact resistance is 10/90 to 70/30.

The unhydrogenated block copolymer of the present invention can be easily obtained by anionic polymerization. Synthesis examples include a method in which a vinyl aromatic compound and isoprene-butadiene are sequentially polymerized using an alkyllithium compound as an initiator, a method in which a vinyl aromatic compound and isoprene-butadiene are polymerized, and then coupled with a coupling agent, or a dilithium compound. Examples include a method in which isoprene-butadiene and a vinyl aromatic compound are sequentially polymerized using as an initiator. Examples of alkyllithium compounds include alkyl compounds in which the alkyl residue has a carbon atom number of 1 to 10, and in particular, ethyllithium, n-propyllithium, n-butyllithium, 5ec-butyllithium, and tert-butyllithium are mentioned. preferable.

As the coupling agent, dichloromethane, dibromomethane, dichloroethane, dibromoethane, etc. are used.

Examples of dilithium compounds include hexamethylene dilithium, naphthalene dilithium, oligostyldili dilithium,
Examples include dilithiohexylbenzene. The amount used is 0.01 to 0.2 parts by weight of each initiator and 0.04 to 0.04 parts by weight of the coupling agent per 100 parts by weight of Kaneko Zimmer used for polymerization.
0.8 parts by weight is suitable.

Examples of organic solvents that can be used during polymerization include aliphatic hydrocarbons such as butane, pentane, n-hexane, isopentane, heptane, and octane, alicyclic hydrocarbons such as cyclobencune, methylcyclobencune, cyclohexane, and methylcyclohexane; Aromatic hydrocarbons such as benzene, toluene, and xylene are exemplified.

Regardless of the polymerization method used, the polymerization is carried out at a temperature range of -20 to 80°C for a period of 1 to 50 hours.

Block copolymers are produced by adding the polymerization solution to a poor solvent such as methanol, coagulating it, and then drying it by heating or under reduced pressure, or by dropping the polymerization solution into boiling water to azeotrope the solvent.
Obtained by heating or drying under reduced pressure.

The obtained block copolymer is hydrogenated according to a known method. A recommended method includes a method in which the block copolymer is dissolved in a solvent that is inert to the hydrogenation reaction and the hydrogenation catalyst, and then reacted with molecular hydrogen. Examples of hydrogenation catalysts include noble metal catalysts such as platinum and palladium, Raney nickel, organic nickel compounds, organic cobalt compounds, and composite catalysts of these compounds and other organic metal compounds. In the hydrogenation reaction, the hydrogen pressure is normal pressure to 200 kg/c and the reaction temperature is room temperature to 250 kg/c.
The reaction time at °C is 0.1 to 100 hours. After the hydrogenation reaction, the block copolymer is produced by coagulating the reaction solution with methanol or the like, then drying it by heating or under reduced pressure, or by pouring the reaction solution into boiling water to remove the solvent by azeotropic distillation, and then drying it by heating or under reduced pressure. It can be obtained by

The hydrogenated block copolymer of the present invention thus obtained can be used by mixing with various thermoplastic resins. Thermoplastic resins that can be used include polyethylene, polypropylene, polyolefin resins made of copolymers of propylene and ethylene or α-olefins such as 1-butene, polystyrene, high impact polystyrene,
ABS.

Examples include styrene resins such as AS, polyester resins such as polyethylene terephthalate and polybutylene terephthalate, polyamide resins such as nylon-6, nylon-66° and nylon-12, polycarbonate resins, and polyphenylene ether resins. Particularly preferred are polypropylene and block copolymers of propylene and ethylene. In addition, the hydrogenated block copolymer of the present invention can be used in polymers for adhesives and adhesives, various molded products, and the like. When used for these purposes, it is possible to add a mineral oil softener called paraffin oil or naphthenic oil, if necessary. In addition, inorganic fillers such as calcium carbonate, talc, carbon black, titanium oxide, silica, clay, barium sulfate, and magnesium carbonate can be mixed for the purpose of improving the heat resistance and weather resistance of the composition or increasing the amount. . Furthermore, it is also possible to mix inorganic or organic fibrous materials such as glass fiber and carbon fiber depending on the purpose.

In addition, it is also possible to add heat stabilizers, antioxidants, light stabilizers, flame retardants, tackifiers, antistatic agents, foaming agents, and the like.

(Examples) In order to explain the present invention more specifically and in detail, Examples of the present invention are shown below, but the content of the present invention is not limited to these Examples.

The performance of the hydrogenated block copolymer obtained according to the present invention was evaluated by the method described below.

a) Glass transition temperature of elastomer block (
Tg) was measured and used as an index of low temperature characteristics.

b) Heat of crystal fusion (ΔH) The heat of crystal fusion of the elastomer block was measured by DSC.

C) Microstructure of elastomer block The conjugated diene The 1.4-bond amount of the polymer block consisting of the following was calculated.

d) A heat-resistant hydrogenated block copolymer was heat-pressed at 230°C to form a 2mm-thick sheet, and this sheet was heated to 150'
After being placed in an air oven (C) for 24 hours, the sheet was taken out and cooled to room temperature. The stickiness of the sheet surface was determined by touch with the finger, and this was used as an index for heat resistance evaluation. Displaying the results is ◎:
Good, ○: average, Δ: slightly poor, ×: poor.

e) Permanent set The sheet prepared in d) above was cut into 1 cm width x 10 cm length, and a marked line of 5CI11 (10) was placed in the center of the test side.
300% at 25°C1 relative humidity 65% atmosphere
(The distance between the gauge lines is 15 cm) After being left for 8 hours, the distance between the gauge lines after being removed from the test equipment for 30 minutes (42)
was measured and the permanent set was calculated using the following formula.

f) Mechanical strength JIS K-6301 using the sheet prepared in d) above
The breaking strength was measured by a method based on .

Example 1 3,000 g of cyclohexane in a pressure vessel with a stirrer
, 50 g of sufficiently dehydrated styrene and 0.7 g of n-butyllithium were added, polymerized at 60°C for 60 minutes, then a mixed monomer of 200 g of isoprene and 100 g of butadiene was added for 60 minutes, and then 50 g of styrene was added and polymerized for 60 minutes.
Polymerization was carried out for 0 minutes to synthesize a styrene-conjugated diene-styrene type triblock copolymer. The obtained block copolymer had a styrene content of 25% by weight, a number average molecular weight of 1,120,000, and a 1.4 bond amount of 88%. The number average molecular weight referred to here is a value measured by gel permutation chromatography (CPC).

Add cyclohexane so that the polymer concentration of this polymer solution is 10% by weight, degas under reduced pressure, replace with hydrogen, and then add 0.5% by weight/polymer of palladium catalyst to 10% by weight.
A hydrogenation reaction was carried out in a hydrogen atmosphere of kg/cnff to obtain a hydrogenated triblock copolymer with a hydrogenation rate of 97%. The physical properties of this hydrogenated block copolymer were evaluated by the method described above, and the results are shown in Table 1.

Comparative Example 1 Compared to Example 1, the mixture ratio of panerene/butadiene = O/1
Hydrogenated block copolymers differing only in that they were set to 00 were prepared, and the physical property evaluation results are shown in Table 1.

It can be seen that this copolymer has a high glass transition temperature (Tg) and large permanent deformation, which is not preferable.

Examples 2 to 4 Triblock copolymers with different hydrogenation rates and 1.4-bond amounts and isoprene/butadiene mixing ratios were prepared compared to those in Example 1, and the physical property evaluation results for each are shown in Table 1. Ta.

Comparative Example 2 A triblock copolymer similar to Example 1 was obtained except that the hydrogenation rate of the elastomer block was 25%. Various physical properties of this copolymer were evaluated and the results are shown in Table 1. From this result, it can be seen that when the hydrogenation rate is low, the heat resistance decreases, which is not preferable.

Furthermore, the compatibility with polypropylene was poor.

Comparative Example 3 A triblock copolymer similar to Example 1 was obtained except that the 1,4-bond content of the elastomer block was 55%, and various physical property evaluations were performed. The results are shown in Table 1. As a result,
The glass transition temperature of the elastomer block of this copolymer is as high as 17°C, indicating that low-temperature flexibility is impaired.

Comparative Example 4 A triblock copolymer similar to that of Example 1 was obtained except that the isoprene/butadiene mixing ratio was 20/80, and various physical property evaluations were performed. The results are shown in Table 1. From this result,
This block copolymer has a high glass transition temperature and large permanent deformation, which is undesirable.

Reference Example 1 Styrene content 25% by weight by the same method as Example 1
A hydrogenated block copolymer consisting of a styrene-isoprene-styrene type triblock with a number average molecular weight of 120,000 was prepared and its physical properties were evaluated.

The results are shown in Table 1. This copolymer has a slightly lower breaking strength than the copolymer obtained in Example I.

The following margin (effects of the invention) The present invention provides a block copolymer obtained by hydrogenating a polymer block consisting of a vinyl aromatic compound and a polymer block consisting of a mixed monomer of isoprene and butadiene. It is rich in flexibility and low-temperature properties, has excellent impact resistance, has low permanent distortion, and has excellent mechanical strength, so it is used in a variety of fields such as daily necessities, industrial goods, food containers, and packaging materials. be able to.

Claims (1)

[Claims] A polymer block (A) consisting of a vinyl aromatic compound,
The amount of 1,4-bonds consisting of isoprene-butadiene is 65
% or more, and consists of a polymer block (B) in which 30% or more of the unsaturated bonds in the chain are hydrogenated, and the heat of crystal fusion of the polymer block (B) is 8 cal/g or less. Block copolymer.