JPH042412B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Field of Application] The present invention relates to a two-color injection molded multilayer molded product in which the outer layer is made of a flexible and scratch-resistant elastomer, while the inner layer is made of a thermoplastic resin that is highly rigid and tough. More specifically, the present invention uses two or more injection molding machines, in which the hydrogenated block copolymer elastomer is charged into one or more injection molding machines, and the hydrogenated block copolymer elastomer is charged into one or more injection molding machines. For example, a thermoplastic resin such as polypropylene resin is put in, first a part of the polypropylene resin is molded, then this is inserted into a mold using a hydrogenated block copolymer elastomer, and the remaining part is molded. It is made by injecting and integrating a hydrogenated block copolymer elastomer. The obtained molded product is a multi-molded product in which the outer layer is flexible and scratch-resistant, and has a rubber-like or leather-like appearance, and the inner layer has sufficient rigidity and impact resistance. [Prior art] Conventionally, push buttons, various key tops,
Two-color molded products made by molding pellets of the same type of plastic, such as ABS resin, in different colors using a two-color injection molding method are used for knobs, automobile blinker lamp covers, and the like. Recently, two-color molded products using different resins have been made, but if the compatibility of both resins is not good, there are problems such as insufficient adhesion, peeling, and the inability to perform slap processing. Combinations are limited. [Problems to be Solved by the Invention] The present invention solves the problems of conventional two-color injection molded products using the same type of plastic in push buttons, key tops, knobs, etc., namely, the outer layer is easily damaged and lacks a soft feel. By making it into a hydrogenated block copolymer elastomer, it was possible to easily obtain a multilayer injection molded product, improve scratch resistance, and successfully impart a soft feel. In addition, by using a thermoplastic plastic, which has been used for the inner layer, there were no problems in terms of rigidity and impact resistance. In addition, in the case of the product of the present invention, the adhesion between the elastomer used for the outer layer and the thermoplastic plastic used for the inner layer is strong, so there is no possibility of peeling.
Since the compatibility between the two is good, it is also possible to mix scrap into the inner layer, which is extremely advantageous from an economic point of view. [Means for solving the problem] That is, the present invention consists of a polymer block A mainly composed of at least two vinyl aromatic compounds and a polymer block B mainly composed of at least one conjugated diene compound. Hydrogenated block copolymer elastomer obtained by hydrogenating block copolymer, polyolefin resin, polystyrene resin,
The present invention provides a multilayer molded product made by molding a resin selected from ABS resin using a two-color injection molding method. The resins used in the present invention have excellent moldability in injection molding, etc., and do not require any special vulcanization reaction.
Because it has excellent reworkability, it can be recycled and the resulting multilayer molded product has the following characteristics: (a) The outer layer is highly flexible, and the inner layer has excellent physical properties such as strength and impact resistance. (b) The outer elastomer layer has excellent scratch resistance,
It has a rubbery, leather-like appearance. (c) When an elastomer layer is used as the inner layer, it has appropriate loosening performance. (d) The outer elastomer layer and the inner thermoplastic plastic layer are strongly bonded. (e) Both the elastomer layer and the thermoplastic layer can be freely colored by mixing dyes and pigments. Among the polymer components of the multilayer molded product of the present invention, the hydrogenated block copolymer used as component (a) consists of at least two polymer blocks A mainly composed of vinyl aromatic compounds and at least one polymer block A mainly composed of vinyl aromatic compounds. It is obtained by hydrogenating a block copolymer consisting of a polymer block B mainly composed of a conjugated diene compound, for example, A-B-A, B-A-B-A,
(A-B) _-4Si , a hydrogenated vinyl aromatic compound-conjugated diene compound block copolymer having a structure such as A-B-A-B-A. This hydrogenated block copolymer contains 5 to 60% by weight, preferably 10 to 50% by weight of a vinyl aromatic compound.Moreover, referring to the block structure, the polymer block A mainly composed of a vinyl aromatic compound is It has 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. and furthermore, a polymer block B mainly composed of a hydrogenated conjugated diene compound.
is a hydrogenated conjugated diene compound polymer block or a hydrogenated conjugated diene compound
It has a structure of a copolymer block of a hydrogenated conjugated diene compound and a vinyl aromatic compound containing more than 50% by weight, preferably 70% by weight or more. In addition, the polymer block A mainly consists of these vinyl aromatic compounds, and the polymer block B mainly consists of hydrogenated conjugated diene compounds.
The distribution of the hydrogenated conjugated diene compound or vinyl aromatic compound in the molecular chain of each polymer block is random, tapered (in which the monomer component increases or decreases along the molecular chain), partially block-like, or They may be composed of any combination, and if there are two or more polymer blocks mainly composed of the vinyl aromatic compound and two or more polymer blocks mainly composed of the hydrogenated conjugated diene compound, each polymer block The combined blocks may each have the same structure or may have different structures. As the vinyl aromatic compound constituting the hydrogenated block copolymer, one or more kinds can be selected from, for example, styrene, α-methylstyrene, vinyltoluene, p-tertiary butylstyrene, etc. Among them, styrene is preferred. Further, as the conjugated diene compound before hydrogenation constituting the hydrogenated conjugated diene compound, for example, one type from butadiene, isoprene, 1,3-pentadiene, 2,3-dimethyl-1,3-butadiene, etc. Or two or more kinds are selected, and among them, butadiene, isoprene and a combination thereof are preferred. The microstructure of the polymer block mainly composed of a conjugated diene compound before hydrogenation can be arbitrarily selected. For example, in the case of a polybutadiene block, the 1,2-microstructure is 20 to 20%.
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 5000 to 5000.
1000000, preferably 10000 to 800000, more preferably 30000 to 500000, and the molecular weight distribution [weight average molecular weight () and number average molecular weight ()
The ratio (/)] is 10 or less. Furthermore, the molecular structure of the hydrogenated block copolymer may be linear, branched, radial, or any combination thereof. These block copolymers may be produced by any method as long as they have the above structure. For example, a vinyl aromatic compound-conjugated diene compound block copolymer is synthesized in an inert solvent using a lithium catalyst or the like by the method described in Japanese Patent Publication No. 40-23798, and then, for example,
By the method described in Japanese Patent Publication No. 8704, Japanese Patent Publication No. 43-6636, or Japanese Patent Application Publication No. 59-133203,
The hydrogenated block copolymer used in the present invention can be synthesized by hydrogenation in an inert solvent in the presence of a hydrogenation catalyst. At that time, the aliphatic double bond based on the conjugated diene compound of the vinyl aromatic compound-conjugated diene compound block copolymer is at least
By hydrogenating 80% of the polymer, a polymer block mainly composed of a conjugated diene compound can be morphologically converted into an olefinic compound polymer block.
In addition, hydrogenation of aromatic double bonds based on vinyl aromatic compounds copolymerized into polymer 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 on the hydrogenation rate, it is preferable that the hydrogenation rate is 20% or less. The amount of terminally hydrogenated aliphatic double bonds contained in the hydrogenated block copolymer can be easily determined using an infrared spectrophotometer, nuclear magnetic resonance apparatus, or the like. The polyolefin resins used as component (b) in the present invention are low density polyethylene resins, linear low density polyethylene resins, medium density polyethylene resins, high density polyethylene resins, polypropylene resins, ethylene-vinyl acetate resins, and ionomer resins. Polystyrene resin is a high impact polystyrene resin containing 2-15% rubber content. ABS resin uses emulsion polymerization method, mass suspension polymerization method,
Acrylonitrile 10-30 produced by mass polymerization method
%, butadiene 5 to 45%, and styrene 50 to 85%, including those using α-methylstyrene in place of styrene. The molded article of the present invention uses two or more injection molding machines, and the hydrogenated block copolymer elastomer is charged into one or more injection molding machines, and the hydrogenated block copolymer elastomer is charged into the other one or more injection molding machines, for example. A thermoplastic resin such as polypropylene resin is introduced, and a portion of the polypropylene resin is first molded, then this is inserted into a mold that uses hydrogenated block copolymer elastomer, and the remaining portion is hydrogenated. The block copolymer elastomer is integrally obtained by injection. The composition of the molded article is preferably (a) 10-90% hydrogenated block copolymer elastomer and 90-10% thermoplastic resin. If necessary, inorganic fillers and plasticizers can be added to the hydrogenated block copolymer to adjust hardness and plasticity. Inorganic fillers used include titanium oxide, calcium carbonate, clay, talc, mica, bentonite, and the like. Plasticizers used include paraffin oil, naphthenic oil, dibutyl phthalate,
Di(2-ethylhexyl) phthalate, di-(2-
Examples include ethylhexyl) adipate, diethylene glycol dibenzoate, butyl stearate, butyl epoxy stearate, tri(2-ethylhexyl) phosphate, and the like. Stabilizers, pigments, etc., which are general additives added to thermoplastic resin materials, can be appropriately added in the case of the present invention as well as conventional polymer resins. [Effects of the Invention] As detailed above, the multilayer molded product of the present invention has flexibility, scratch resistance, and
It has excellent cushioning properties, weather resistance, etc., and the thermoplastic inner layer provides high strength, high bending modulus, and excellent impact resistance, and both are bonded with high adhesive strength. Therefore, push buttons, various key tops and knobs of OA equipment,
It is extremely suitable for use in automobile turn signal lamp covers, etc. [Example] The present invention will be specifically explained with reference to Examples below, but the scope of the present invention is not limited thereto. The test method used in the examples is as shown below. Hardness (Shore D): ASTM D2240 Hardness (Rockwell R): ASTM D785 Tensile strength: JIS K6301 Elongation: Same as above Izotsu impact strength: ASTM D746 Vikatsu softening point: ASTM D1525 Example 1 Two-color injection made by Nissei resin A molding machine was used to mold pushbuttons and keys whose outer layer is a hydrogenated block copolymer and whose inner layer is an ABS layer. That is, first, a part of Stylac ABS183 manufactured by Asahi Kasei Industries, Ltd. was molded into a two-color mold, this was then molded into another mold, and the remaining part was bonded with styrene 30.
%, a vinyl content of 30%, a molecular weight of 50,000, and a hydrogenated block copolymer is formed and integrated. The product of the present invention has (1) a flexible outer layer and a soft feel;
(2) The inner layer was rigid, not easily deformed, and had heat resistance, and (3) the outer layer and inner layer were strongly bonded.

[Table] Example 2 The molding machine of Example 1 was used, and polypropylene resin was used instead of ABS resin. Also, instead of hydrogenated block copolymer, hydrogenated block copolymer
An elastomer consisting of 32% polypropylene resin, 45% paraffin oil, and 10% calcium carbide was used. The product of the present invention has (1) an outer layer that is flexible and has a soft feel;
(2) The inner layer is rigid, difficult to deform, and heat resistant. (3) The outer layer and inner layer are strongly bonded. Next, the physical properties of the product of the present invention are shown in Table-2.

【table】

Claims (1)

[Scope of Claims] 1(a) A block copolymer consisting of a polymer block A mainly composed of at least two vinyl aromatic compounds and a polymer block B mainly composed of at least one conjugated diene compound. Hydrogenated block copolymer elastomer obtained by hydrogenation and (b) polyolefin resin, polystyrene resin,
A multilayer injection molded product made using a two-color injection molding method with a resin selected from ABS resin.