JPH034569B2 - - Google Patents

Description

[Detailed description of the invention]

(a) Purpose of the invention (industrial application field) This invention relates to plastic molded products. More specifically, the present invention relates to a plastic molded product based on a resin that is flexible, has excellent transparency and high-temperature strength, and has low toxicity. (Prior Art) Various molding resin compositions have been proposed and put into practical use for producing transparent and flexible molded products in the fields of food packaging materials, medical instruments, and the like. Among these, resin compositions and molded products using soft polyvinyl chloride have excellent flexibility and transparency, and have a tensile strength of about 200 kg/ ^cm2 , and can maintain their shape even at high temperatures of about 120°C. Because it has sufficient strength, it can be sterilized at high temperatures, and is widely used not only in the general packaging industry but also in food packaging, medical instruments, etc. However, since soft polyvinyl chloride usually contains a large amount of plasticizer, the plasticizer gradually evaporates and hardens, and especially in packaging bags, tubes, etc., the plasticizer transfers to the contents, resulting in sanitary hygiene. This may cause problems. In addition, unless the amount of vinyl chloride monomer remaining in the molded product was extremely reduced, there was a risk of hygienic problems. In this regard, a block polymer such as a styrene-butadiene-styrene block copolymer or a styrene-isoprene-styrene block copolymer is further added to water to create a molding resin composition that does not contain a plasticizer and has various physical properties such as transparency and flexibility. A mixed resin based on a hydrogenated block copolymer obtained by addition treatment and mixed with polypropylene and an ethylene-vinyl acetate copolymer resin, and a mixed resin based on the above-mentioned hydrogenated block copolymers and mixed with polypropylene and ethylene acrylate. A mixed resin made by blending the
-88950, JP-A-59-74153). (Problems to be Solved by the Invention) As mentioned above, the mixed resin using the hydrogenated block copolymer, polypropylene, and ethylene-vinyl acetate copolymer or ethylene-acrylate copolymer is useful for various uses. be. However, for example, infusion bags, etc., are basically composed of a combination of molded parts consisting of a bag-shaped molded body and a tube-shaped molded body, so these parts need to be joined. Production is also carried out by joining and integrating these molded parts by physical means such as heat sealing, ultrasonic sealing, impulse sealing, etc., but there is a problem that the joining process itself is difficult. In order to perform the bonding process more easily, it is desirable to use an adhesive, but no suitable adhesive for the above mixed resin has been found, for example, rubber-based solution-type adhesives, vinyl acetate-based adhesives, and acrylic ester adhesives. emulsion and solution adhesives,
Even if a known adhesive such as a urethane solution type adhesive was used, a practically satisfactory bonding strength could not be obtained and the bonding could not be integrated. This invention has been made in view of the above problems, and it is an object of the present invention to provide a plastic molded product that can be easily joined and integrated. As a result of intensive research, the present inventors discovered that when joining molded parts made of the above mixed resin, an organic solvent solution of a hydrogenated block copolymer, which is one of the constituent resin components of the mixed resin, was used as an adhesive. We have discovered that by using this method, these molded parts can be joined together with excellent adhesive strength. (b) Structure of the invention Thus, according to this invention, the resin composition has the following range: a. Both ends of a block copolymer consisting of both end blocks made of a polymer of an aromatic vinyl compound and an intermediate block made of a conjugated diene polymer A block copolymer in which the block is 10 to 40% by weight of the copolymer, less than 10% of which is hydrogenated, and the intermediate block is 90% or more hydrogenated: 30% to 90% by weight
Weight%, b Isotactic polypropylene with a melting point of 150°C or higher or a copolymer mainly composed thereof: 5% to 40% by weight, and c Ethylene-acrylate copolymer with an acrylate content of 5% or higher, or vinyl ester Content 5
% or more of ethylene-vinyl ester copolymer:
5% to 40% by weight, and these molded parts are joined together using an organic solvent solution of the block copolymer a as an adhesive. provided. The plastic molded article of the present invention is composed of at least two or more molded article parts, and these parts are integrated. Specific molded product parts include sheet-like molded products, bag-like molded products, tube-like molded products, and various other irregularly shaped products. Of course, these molded parts may themselves have portions joined by heat sealing, ultrasonic sealing, or the like. A representative example of the plastic molded article to which the present invention is applied is a bag-shaped molded article in which a bag-shaped molded article and a tube-shaped molded article made of the above-mentioned mixed resin are joined and integrated. Such bag-shaped molded products have high transparency, excellent flexibility,
It has high strength at high temperatures and is non-toxic (contains no plasticizer), making it particularly useful as medical bags such as infusion bags and blood bags. An example of such a bag-shaped molded article of the present invention is shown in FIG. In the figure, reference numeral 1 shows the infusion bag of the present invention, in which the tips of three tube-shaped molded bodies 2 are respectively fitted into the holes 4 of the bag-shaped molded body 3, and the holes 4 and the tube-shaped molded bodies 2 are connected. It is obtained by applying an organic solvent solution of the block copolymer to the contact part (fitting part) and drying it, whereby the bag-shaped molded body 3 and the tube-shaped molded body 2 are joined and integrated. It is what it is. Component a in the mixed resin that serves as the base resin for the molded product parts of this invention consists of an intermediate block (90 to 60% by weight) made of a conjugated diene copolymer and both end blocks made of an aromatic vinyl compound polymer at both ends. This is a hydrogenated block copolymer obtained by hydrogenating a block copolymer consisting of (10 to 40% by weight). Polystyrene, poly-alpha
-methylstyrene, poly-p-methylstyrene,
There are styrenic polymers such as polychlorostyrene, but their number average molecular weight is 5,000 to 125,000.
Suitable materials are polystyrene, and polystyrene is most preferred. On the other hand, conjugated diene polymers constituting the intermediate block include polybutadiene, polyisoprene, polychloroprene, etc., but those having a number average molecular weight of 10,000 to 300,000 are suitable, and polybutadiene and polyisoprene are particularly preferred. It is. The block copolymer used in the present invention can be obtained by hydrogenating the above block copolymer. At that time, the hydrogenation ratio of both end blocks should be 10% or less.
The hydrogenation ratio of the intermediate block must be 90% or more. In particular, the hydrogenation ratio in the intermediate block is 95
% or more. This means that, for example, if the intermediate block is polybutadiene, the hydrogenated product will have an ethylene-butylene copolymer structure, and if the intermediate block is polyisoprene, the hydrogenated product will have an ethylene-propylene copolymer structure. This is because heat resistance and weather resistance are improved, and in particular, the molded article of the present invention has excellent heat resistance (high temperature strength). In addition, the blocks at both ends are 15~
Preferably it is 25% by weight. The block copolymers a used in the present invention are Kraton G-1650, Kraton G-1652, Kraton G
-1657, Kraton G-1658 (all manufactured by Shell Chemical), and other names. Also,
These block copolymers are not limited to one type, and may be used in combination of two or more types. Next, the polypropylene used as the component b used in the present invention is an isotactic polypropylene having a melting point of 150 DEG C. or higher, or a copolymer mainly composed of it, and those commonly used as molding materials can be used as they are. As the copolymer, block copolymers and random copolymers of propylene and α-olefins such as ethylene and 1-butene can be used, but in order to maintain the flexibility of the composition of the present invention, flexible copolymers are preferred, especially random copolymers. is suitable. Next, it is necessary that the ethylene-acrylate copolymer of component c used in the present invention has an acrylate content of 5% or more. Acrylate content is 5%
Below this, the transparency of the composition itself decreases and the flexibility of the composition is also insufficient. Ethylene used in the present invention
Acrylates used in the acrylate copolymer include methyl acrylate, ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, and methacrylic esters corresponding to these. Most preferred are methyl acrylate and ethyl acrylate. On the other hand, as component c, the vinyl ester content is 5
% or more of ethylene-vinyl ester copolymer can also be used. Vinyl esters in such ethylene-vinyl ester copolymers include vinyl formate, vinyl acetate, vinyl propionate,
Examples include vinyl butyrate and vinyl stearate, but the most preferred is vinyl acetate. The maximum content of these acrylates or vinyl esters in the copolymer is not particularly limited, but is suitably up to about 30%. In addition, it is preferable to use an ethylene-acrylate copolymer in terms of low-temperature flexibility, high-temperature strength, stability, and the like. This invention is most characterized in that a plurality of molded parts made of the above mixed resin are adhesively bonded using an organic solvent solution of the block copolymer a. As the organic solvent solution of block copolymer a, one containing 5 to 30% by weight of the block copolymer is suitable. If it is less than 5% by weight, the adhesive strength will be insufficient, which is undesirable, and if it exceeds 30% by weight, the viscosity of the solution will become too high, making it difficult to coat the surface uniformly, and making it easy for bubbles to be mixed in, which is not preferable. The most preferred concentration is 8-15% by weight.
Further, as the solvent for the organic solvent solution, aromatic solvents such as benzene, toluene, and xylene, hydrocarbon solvents such as hexane, chloroform, 1,2
- Halogenated hydrocarbon solvents such as dichloroethane, ketone solvents such as cyclohexanone, and ether solvents such as tetrahydrofuran are suitable. A desired molded product can be obtained by applying the organic solvent solution to the intended joint of a plurality of molded product parts and drying it. Application may be carried out by dipping or firming, but it is usually easier to apply by dropping the solution onto the joint area. In addition to the above-mentioned essential main resin components, the mixed resin used in the present invention may have flexibility, transparency,
Various plasticizers, anti-blocking agents, sealability improvers, heat stabilizers, antioxidants, ultraviolet absorbers, lubricants, crystal nucleating agents, colorants, etc. in amounts that do not impede high-temperature strength, moldability, and safety. It is also possible to contain. (Examples) Hereinafter, this invention will be explained in detail with reference to Examples, but this invention is not limited thereby. Example 1 Thickness of a blend with the following composition as an adherend
A 0.32mm sheet was used. a Block copolymer (i) Kraton G-1652 37% by weight (manufactured by Schiel Chemical) (ii) 〃 1657 20 〃 ( 〃 ) b Polypropylene 20 〃 (Random copolymer with a melting point of 165°C) c Ethylene-ethyl acrylate copolymer 23 〃 (NUC-6220 manufactured by Nippon Unicar, ethyl acrylate content 7%) In addition, Kraton G-1652 and Kraton G-
1657 is a block copolymer in which the blocks at both ends are polystyrene and the hydrogenated block in the middle is an ethylene-butylene copolymer.
The ratio of G-1652 to butylene copolymer is 28:72,
G-1657 is 14-86. Further, the viscosity (77〓) of a 20% by weight toluene solution of G-1652 is 550CP. There is no organic solvent that completely dissolves the above sheet at room temperature.
I also tested various commercially available adhesives, but they all gave T-
The peel strength was less than 1 kg/25 m/m, which was completely insufficient. On the other hand, Kraton G-1650 (manufactured by Shell Chemical; like Kraton G-1652, both end blocks are polystyrene and the central hydrogenated block is ethylene).
A solution of a block copolymer (a butylene copolymer) with a ratio of 28:72 and a 20% by weight toluene solution with a viscosity (77〓) of 1500CP) dissolved in the following solvent at the following concentration. was prepared and used to evaluate the adhesiveness of the sheet. The results are also shown in the table below.

[Table] Good results were obtained in all cases, but adhesive strength was particularly excellent at concentrations of 5% or higher. Comparative Example 1 As the resin used for the adhesive, Cauliflex TR- was used instead of Kraton G-1650 in Example-1.
1101 (manufactured by Ciel Chemical, a block copolymer in which both end blocks are polystyrene and the middle block is polybutadiene, the ratio of the former to the latter is 30/70).
% benzene and cyclohexanone solution was prepared and an adhesion test was conducted on the sheet of Example-1.
In either case, the adhesive surface was easily peeled off by hand and was completely unsatisfactory. Example 2 As an adherend, an ethylene-vinyl acetate copolymer (DQDJ-1830 manufactured by Nippon Unicar, vinyl acetate content 10%) was used instead of the ethylene-acrylate copolymer in c of Example-1. A sheet with a height of 0.32 m/m was produced. When this sheet was bonded using the adhesive of Example 1 (10% benzene solution of Kraton G-1650), the T-peel strength was 6.0 kg/25 m/
It was satisfactory. Example 3 Thickness of a blend with the following composition as an adherend
0.35m/m seat and outer diameter 8m/m, inner diameter 6
A m/m tube was used. a Block copolymer (i) Kraton G-1652 42% by weight (ii) 〃 1657 25 〃 b Polypropylene 15 〃 (Random copolymer with a melting point of 165°C) c Ethylene-ethyl acrylate copolymer 18 〃 (Nippon Unicar DPDJ-6182) , ethyl acrylate content 15%) d Lubricant 0.3 parts A bag was made from these two sheets by heat sealing. A thin Teflon film with a width of 12.5 m/m was sandwiched between the two exits, and these parts were left as openings without sealing. Insert the above tubes into the two outlets of this bag, use a dropper to suck up a 15% benzene solution of Kraton G-1650, and apply it to the joint to make a strong bond within a few minutes. done. (c) Effects of the Invention As stated above, the plastic molded product of the present invention is strongly integrated as a plurality of molded product parts are joined with a specific adhesive. Therefore, even in the place where the molded product is used, the molded product parts can be easily combined and configured. Such plastic molded articles are particularly suitable as molded articles in the field of medical devices because of their transparency, flexibility, high-temperature strength, non-toxicity, and the like.

[Brief explanation of drawings]

FIG. 1 is a perspective view showing a specific example of the plastic molded product of the present invention. 1... Infusion bag, 2... Tube-shaped molded body,
3... Bag-shaped molded body, 4... Hole.

Claims (1)

[Scope of Claims] 1. Resin composition within the following range: a. A block copolymer consisting of both end blocks made of a polymer of an aromatic vinyl compound and an intermediate block made of a conjugated diene polymer, in which both end blocks are in the copolymer. Block copolymer of 10 to 40% by weight, 10% or less of which is hydrogenated, and 90% or more of the intermediate block is hydrogenated: 30 to 90% by weight
Weight%, b Isotactic polypropylene with a melting point of 150°C or higher or a copolymer mainly composed thereof: 5% to 40% by weight, and c Ethylene-acrylate copolymer with an acrylate content of 5% or higher, or vinyl ester Content 5
% or more of ethylene-vinyl ester copolymer:
5% to 40% by weight, and these molded parts are joined together using an organic solvent solution of the block copolymer a as an adhesive. 2. The plastic molded article according to claim 1, wherein the plurality of molded article parts include a bag-shaped molded body and a tube-shaped molded body. 3 The organic solvent solution of block copolymer a is
The plastic molded article according to claim 1, which is an organic solvent solution having a concentration of 30% by weight.