JPH0562136B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention is a transparent hydrogenated block copolymer that has excellent moldability, flexibility, transparency, heat deformation resistance, compression set, mechanical strength, and sanitary safety. The present invention relates to a high modulus elastomer composition. [Prior Art] Various molding materials have been proposed to obtain transparent and flexible molded products in the fields of food packaging materials and medical instruments. Examples of these include ethylene-vinyl acetate copolymer, ethylene-acrylate copolymer, flexible polyvinyl chloride, ethylene-propylene copolymer, polyurethane elastomer, polyester elastomer, and the like. However, these molding materials currently have their own drawbacks in terms of mechanical strength, flexibility, transparency, economic efficiency, heat resistance, and hygiene. Although it has excellent flexibility, transparency, mechanical strength, and heat resistance, it usually contains a large amount of plasticizer, so it is predicted that plasticizer will migrate to the contents in food packaging, medical equipment, etc. It is well known that this is undesirable from a sanitary standpoint. Therefore, in these application fields such as food packaging and medical equipment, there is a strong need for molding materials that have excellent flexibility, mechanical strength, transparency, heat resistance, hygiene, and moldability. be. As one of the proposals for molding materials that take these characteristics into consideration,
Publication No. 74153 proposes a resin composition containing a hydrogenated block copolymer as a main component. [Problems to be solved by the invention] However, the resin composition proposed here has the following problems:
Although it is a molding material with good transparency and high-temperature strength, when used as molded products such as food packaging and medical instruments, it does not exhibit sufficient rubber elasticity during high-temperature heat sterilization operations of 120℃ or higher, and its rubber-like molding At present, the shape retention of products (eg tubes, medical bags, etc.) is still insufficient. [Means for Solving the Problems] The present invention was made to solve the problems that were difficult to solve with the conventional molding materials mentioned above.
This was created based on the need for a molding material that maintains transparency, exhibits sufficient rubber elasticity even during high-temperature heat sterilization, and has excellent heat-resistant shape retention for molded products. A composition consisting of a combination of a block copolymer and a specific resin exhibits a total light transmittance of 70% or more and a compression set (70℃
It has been found that the above-mentioned requirements can be achieved with a performance of 60% or less (22 hours), and the composition is also found to be a practically useful composition. The present invention provides (i) a polymer block A having a number average molecular weight consisting of a polymer block A mainly consisting of at least one vinyl aromatic compound and a polymer block B mainly consisting of at least one hydrogenated conjugated diene compound; Hydrogenated block copolymer with 100,000 to 400,000 40 to 85
(ii) 5 to 30% by weight of crystalline polypropylene or a copolymer containing it as a main component. (iii) 5-30% by weight of an ethylene-acrylate copolymer with an acrylate content of 5% or more; (iv) 5-30% by weight of a crystalline low-molecular-weight polypropylene with a number average molecular weight of 20,000 or less, with a total light transmittance of 70%. % or more and compression set (70°C x 22 hours) is 60% or less. The present invention will be described in detail below. The hydrogenated block copolymer used as component (i) in the present invention is composed mainly of a polymer block A mainly composed of at least one vinyl aromatic compound and at least one hydrogenated conjugated diene compound. It has a structure consisting of a polymer block B, for example, ABA, B-A-B-A, B-
A-B-A-B, (A-B) ₄ --Si(B-A-B) ₄
---
It is a hydrogenated block copolymer composed of Si, AB, a mixture thereof, etc. Furthermore, this hydrogenated block copolymer contains 5 to 60% by weight, preferably 10 to 40% by weight of a vinyl aromatic compound.Moreover, referring to the block structure, the polymer block A, which is mainly composed of a vinyl aromatic compound, contains a vinyl aromatic compound. , having a structure of a vinyl aromatic compound polymer block or a copolymer block of a vinyl aromatic compound containing more than 50% by weight and preferably 70% by weight or more and a hydrogenated conjugated diene compound. Further, preferably, the polymer block B mainly composed of a hydrogenated conjugated diene compound contains more than 50% by weight of the hydrogenated conjugated diene compound polymer block or the hydrogenated conjugated diene compound. has a structure of a copolymer block of a hydrogenated conjugated diene compound and a vinyl aromatic compound containing 70% by weight or more. In addition, polymer block A mainly composed of vinyl aromatic compounds and polymer block B mainly composed of hydrogenated conjugated diene compounds are composed of hydrogenated conjugated diene compounds in the molecular chains of each polymer block. Alternatively, the distribution of the vinyl aromatic compound may be random, tapered (monomer component increases or decreases along the molecular chain), partially block-like, or any combination of these. When there are two or more polymer blocks mainly composed of a polymer block and two or more polymer blocks mainly composed of a hydrogenated conjugated diene compound, each block may have the same structure or a different structure. . As the vinyl aromatic compound constituting the hydrogenated block copolymer, one or more kinds are selected from, for example, styrene, α-methylstyrene, vinyltoluene, p-tert-butylstyrene, etc. Among them, styrene is preferable. Further, examples of the conjugated diene compound before hydrogenation constituting the hydrogenated conjugated diene compound include butadiene, isoprene, 1,3-pentadiene, 2,3-dimethyl-
One or more types are selected from 1,3-butadiene and the like, and among them, butadiene, isoprene, and a combination thereof are preferred. The microstructure of a polymer block mainly composed of a conjugated diene compound before being hydrogenated can be arbitrarily selected; for example, in a polybutadiene block, the 1,2-microstructure is 20 to 50.
%, preferably 25-45%. Further, the number average molecular weight of the hydrogenated block copolymer used in the present invention having the above structure is 100,000 to 100,000.
400,000, and the specified essential structure for the composition of the present invention to have a compression set (70°C x 22 hours) of 60% or less and exhibit excellent high elasticity. be. Hydrogenated block copolymers with a number average molecular weight of less than 100,000 do not exhibit excellent high elasticity, with the compression set (70°C x 22 hours) of the resulting composition exceeding 60%. Also, the number average molecular weight is 400000
A hydrogenated block copolymer exceeding 100% of the total number of hydrogenated block copolymers exhibits excellent high elasticity, but has poor processability and is therefore undesirable. The molecular structure of the hydrogenated block copolymer provided in the present invention may be linear, branched, radial, or any combination thereof, and any molecular structure having the above-mentioned structure and essential structure may be used. It may be obtained by such a manufacturing method. For example, a vinyl aromatic compound-conjugated diene compound block copolymer is synthesized in an inert solvent using a lithium catalyst using the method described in Japanese Patent Publication No. 40-23798, and then
It can be synthesized by hydrogenation in an inert solvent in the presence of a hydrogenation catalyst according to the method described in Japanese Patent No. -8704. In this case, at least 80% of the aliphatic double bonds based on the conjugated diene compound of the vinyl aromatic compound-conjugated diene compound block copolymer are hydrogenated, and the polymer block mainly composed of the conjugated diene compound is morphologically olefinic. The compound can be converted into polymer block B. Also,
Regarding the hydrogenation rate of aromatic double bonds based on the vinyl aromatic compounds copolymerized into block A mainly composed of vinyl aromatic compounds and, if necessary, polymer block B mainly composed of conjugated diene compounds, Although there is no particular restriction, it is preferable that the hydrogenation rate is 20% or less. The amount of unhydrogenated aliphatic double bonds contained in the hydrogenated block copolymer can be easily determined using an infrared spectrophotometer, nuclear magnetic resonance apparatus, or the like. Next, the crystalline polypropylene used as component (ii) of the present invention or a copolymer mainly composed thereof has an MFI (230°C, 2.16 kg load) of 0.2 to 15, for example.
g/10 min, which is generally used for molding, improves the mechanical strength, heat deformation resistance, and hardness of the resulting composition, and further processes the hydrogenated block copolymer serving as component (i). It is an essential component to dramatically improve properties, and component (ii) includes polypropylene, propylene and ethylene, and
Examples include random copolymers and block copolymers with α-olefins such as -butene. Furthermore, ethylene used as component (iii) of the present invention
The acrylate copolymer improves the transparency and low-temperature flexibility of a composition consisting of two components, hydrogenated block copolymer (i) and polypropylene (ii). Processability of hydrogenated block copolymers can be improved. The ethylene-acrylate copolymer used as component (iii) must have an acrylate content of 5% or more,
If the acrylate content is less than 5%, the flexibility of the resulting composition will be poor and the transparency will be significantly reduced, which is not preferable. Examples of the acrylate include methyl acrylate, ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, and among them, ethyl acrylate is preferred. Furthermore, the crystalline low molecular weight polypropylene with a number average molecular weight of 20,000 or less used as component (iv) improves the transparency of the resulting composition, especially the total light transmittance, and furthermore, the hydrogenated polypropylene used as component (i) It is an essential component for dramatically improving the processability of block copolymers. The crystalline low-molecular-weight polypropylene that can be provided here is generally produced industrially by thermal decomposition of high-molecular-weight polypropylene, but it may also be one that is by-produced during the production of high-molecular-weight polypropylene. Average molecular weight less than 20000, softening point 145-155℃,
Crystalline low molecular weight polypropylene having a density of about 0.89 is useful. The composition of the present invention comprising the essential components (i), (ii), (iii), and (iv) described above contains the hydrogenated block copolymer (i).
The hydrogenated block copolymer contains 40 to 85% by weight.
flexibility of the resulting composition if less than 40% by weight;
Transparency is poor, compression set (70°C x 22 hours) is poor, and desirable rubber elasticity at high temperatures cannot be obtained. Moreover, if it exceeds 85% by weight, the effect of adding components (ii), (iii), and (iv) described below will be reduced, which is undesirable. Next, component (ii) polypropylene is 5% in the composition.
~30% by weight, and the polypropylene is 5% by weight
If it is less than 10%, the heat deformation resistance and moldability of the resulting composition will be poor, which is not preferable. If the amount exceeds 30% by weight, the flexibility and transparency of the resulting composition will deteriorate, compression set will worsen, and desirable rubber elasticity at high temperatures cannot be obtained. The ethylene-acrylate copolymer of component (iii) is contained in the composition in an amount of 5 to 30% by weight,
If the amount of the ethylene-acrylate copolymer is less than 5% by weight, it is not possible to maintain the low flexibility of the resulting composition, and in particular, it is not possible to achieve improvement in transparency, which is not preferable. Moreover, if it exceeds 30% by weight, heat deformation resistance and transparency will deteriorate, which is undesirable. In particular, compression set will deteriorate significantly, and rubber elasticity at high temperatures will be lost, which is undesirable. Component (iv), the crystalline low molecular weight polypropylene, is contained in the composition in an amount of 5 to 30% by weight; if it is less than 5%, the molding processability of the resulting composition is poor, particularly in terms of transparency, especially total light transmittance. Unfavorable as improvement cannot be achieved. If the amount exceeds 30% by weight, the flexibility and mechanical strength of the resulting composition will be poor, and the compression set will worsen, making it impossible to obtain desirable rubber elasticity at high temperatures. Note that the crystalline low molecular weight polypropylene used as component (iv) in the composition of the present invention can improve the total light transmittance of the composition obtained as described above and improve the transparency, but it can also be used in the composition other than the present invention. Even in compositions made of hydrogenated block copolymers with a number average molecular weight of less than 100,000 that have a total light transmittance of 70% or more and a compression set of more than 60%, the total light transmittance can be improved and the transparency can be improved and processed. Improved sexual performance can be achieved. The above-mentioned composition of the present invention may be used as necessary, as long as it does not adversely affect flexibility, transparency, rubber elasticity at high temperatures (compression set), heat deformation resistance, moldability, hygiene, and mechanical strength. , number average molecular weight
Hydrogenated block copolymers of less than 100,000, various plasticizers, antioxidants, heat stabilizers, ultraviolet absorbers, hindered amine light stabilizers, antiblocking agents, lubricants, sealing property improvers, crystal nucleating agents, It is also possible to add pigments, inorganic fillers, other polyolefin resins, etc. The composition of the present invention can be formed into a sheet by mixing the components (i) to (iv) in a Henschel mixer, blender, etc., kneading with heated rolls, and easily forming a sheet by hot pressing, or by uniaxial extrusion. It can be pelletized using a machine, twin-screw extruder, etc., and then extruded into tubes, nets, irregularly shaped products, sheets, blocks, etc. Furthermore, processing methods such as injection molding and blow molding can be applied to form various molded products. [Effects of the Invention] The composition obtained by the present invention has excellent transparency, flexibility, heat deformation resistance, mechanical strength, and rubber elasticity at high temperatures, as well as excellent molding processing methods and electrical insulation properties. It can be useful in fields such as various electric wire coatings, automobile parts, electrical products, and household goods, but it is particularly characterized by excellent transparency, rubber elasticity at high temperatures (compression set), heat deformation resistance, and sanitary safety. Because there is
It is useful in the fields of food packaging materials and medical equipment that require high temperature sterilization, such as artificial dialysate bags,
It can be molded into medical bags such as blood bags and infusion bags and used suitably. (Example) Examples are shown below, but these are intended to explain the present invention more specifically, and the present invention is not limited to these examples. The various physical properties measured in Examples and Comparative Examples were performed by compression molding a 0.5 mm thick sheet under conditions of 200° C. and 100 Kg/cm ² and using the following test method. (1) Tensile strength and tensile elongation: Measured according to JIS-K6301. (Sheet thickness: 2 mm) (2) Total light transmittance and haze: Measured according to ASTM-D1003. (3) Shore hardness: Measured according to ASTM-D-1706. (4) Compression set: JIS-K-6301, 70°C, 25% deformation, 22 hours storage Comparative example 1 Kraton G- as hydrogenated block copolymer
40% by weight and 20% by weight of 1650 and G-1657 (both manufactured by Ciel Chemical Co., Ltd.), polypropylene resin (MFI = 14, Asahi Polypro M-1600; manufactured by Asahi Kasei Co., Ltd.)
Ethylene-ethyl acrylate copolymer (NUC-
6220 (manufactured by Nippon Unicar Co., Ltd.) was kneaded and granulated using a twin-screw extruder, and a test piece was prepared using a prescribed method to measure the physical properties.The total light transmittance was 83%.
Haze is 11%: Compression set (70℃ x 22 hours) is 67
%; tensile strength was 310 Kg/cm ² , elongation was 580%, and hardness was 37. Examples 1, 2, Comparative Examples 2, 3 Polystyrene-hydrogenated polybutadiene-polystyrene structure, combined styrene amount 33
%, number average molecular weight 133000, molecular weight distribution 1.06, the amount of 1 and 2 bonds in the polybutadiene moiety before hydrogenation is 40%, and the hydrogenation rate is 94%. Hydrogenated block copolymer and polypropylene (Asahi Polypro M-1600; Asahi Kasei Co., Ltd.) Co., Ltd.), an ethylene-ethyl acrylate copolymer (containing 7% ethyl acrylate), and a crystalline low molecular weight polypropylene with a number average molecular weight of 4000 were blended in the composition shown in Table 5, and various physical properties were measured using prescribed methods. Table 5 shows the results.
Shown below. It should be noted that Example 1 shows an improvement in total light transmittance compared to Comparative Example 2, and the effect of adding crystalline low molecular weight polypropylene is exhibited. Similarly, in comparison with Comparative Example 3, it can be seen that in Example 2, the total light transmittance was greatly improved by adding crystalline low molecular weight polypropylene.

[Table] Comparative Examples 4 to 7 Polystyrene-hydrogenated polybutadiene-polystyrene structure, combined styrene amount 34
%, number average molecular weight 58000, molecular weight distribution 1.04, the amount of 1 and 2 bonds in the polybutadiene part before hydrogenation is 40%, and the same as Examples 1 and 2 except that a hydrogenated block copolymer with a hydrogenation rate of 96% is used. The compositions were mixed and various physical properties were measured using predetermined methods. The results are shown in Table 2. As can be seen from Table 2, when a hydrogenated block copolymer having a molecular weight outside the range specified by the present invention is used, it exhibits performance exceeding 60% compression set.
Further, when Comparative Examples 4 and 5 are compared, Comparative Example 5, in which crystalline low molecular weight polypropylene was added, shows an improvement in total light transmittance. Similarly, it can be seen that the effect of adding crystalline low molecular weight polypropylene was also expressed in Comparative Examples 6 and 7. Although Comparative Examples 4 to 7 listed here have a total light transmittance of 70% or more and are excellent in transparency, their compression set performance exceeds 60% and therefore cannot be used as the composition of the present invention.

【table】

[Table] Comparative Example 8 Hydrogenated polybutadiene-polystyrene-hydrogenated polybutadiene-polystyrene structure, amount of bound styrene 30%, number average molecular weight 163000, molecular weight distribution 1.07, 1 of the polybutadiene portion before hydrogenation , 45% by weight hydrogenated block copolymer with 2 bond content of 38%, hydrogenation rate of 97%, and ethylene content of 5%.
polypropylene random copolymer (MFI=8)
25 parts by weight and 30 parts by weight of ethylene-ethyl acrylate copolymer with 7% ethyl acrylate content were blended and granulated using a twin-screw extruder, test pieces were prepared, and various physical properties were measured using prescribed methods. 21%, total light transmittance 79%, compression set 60%, tensile strength 290 Kg/cm ² , elongation 710%, and hardness 44. Example 3 10wt of the PP random copolymer used in Comparative Example 8
%, ethylene-ethyl acrylate copolymer
Reduced to 15wt% and newly number average molecular weight of 15000
A composition containing 30% by weight of crystalline low molecular weight polypropylene and 45% by weight of the hydrogenated block copolymer used in Example 5 had a haze of 23% and a total light transmittance.
The physical properties were 88%, compression set 60%, tensile strength 250 Kg/cm ² , elongation 640%, and hardness 39. Examples 4 to 6 Hydrogenated polybutadiene-polystyrene-hydrogenated polybutadiene-polystyrene structure, amount of bound styrene 36%, number average molecular weight 108000, molecular weight distribution 1.04, 1, 2 of polybutadiene before hydrogenation Hydrogenated block copolymer () with a bond amount of 42% and a hydrogenation rate of 97%, (polystyrene-hydrogenated polybutadiene) ₄ ---Si structure, a bonded styrene content of 16%, and a number average molecular weight of 384,000 , molecular weight distribution 1.3, hydrogenated block copolymer () with a 1 and 2 bond content of polybutadiene before hydrogenation of 40% and a hydrogenation rate of 95%, polypropylene (Asahi Polypro M-1600; manufactured by Asahi Kasei Corporation) ethylene acrylate content 7%, 20%
Ethylene-ethyl acrylate copolymer (EEA) and crystalline low molecular weight polypropylene (number average molecular weight 15,000) were blended in the composition shown in Table 3, and various physical properties were measured using prescribed methods. The results are shown in Table 3.

【table】

Claims (1)

[Claims] 1(i) Consisting of a polymer block A mainly composed of at least one vinyl aromatic compound and a polymer block B mainly composed of at least one hydrogenated conjugated diene compound The number average molecular weight is
100000~400000 hydrogenated block copolymer 40~85
(ii) 5-30% by weight of crystalline polypropylene for general molding or a polymer mainly composed of it; (iii) 5-30% by weight of ethylene-acrylate copolymer with an acrylate content of 5% or more; (iv) ) Consisting of 5 to 30% by weight of crystalline low molecular weight polypropylene with a number average molecular weight of 20,000 or less, with a total light transmittance of 70% or more and a compression set (70℃ x 22
A transparent high modulus elastomer composition with a performance of 60% or less.