JP2640004B2 - OA, molded products of home appliances - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial application field) The present invention relates to a molded article of a chassis for OA and home electric appliances,
More specifically, the present invention relates to a chassis molded article of OA and home electric appliances, which is excellent in chemical resistance, heat resistance, dimensional stability method, impact resistance, paintability, and the like.

(Prior Art) In recent years, chassis for OA equipment such as printers and facsimile machines have been transitioning from metal to plastic for the purpose of largely reducing costs and weight including assembly processing costs. At present, glass fiber (hereinafter referred to as GF) reinforced PC resin, GF reinforced modified PPO resin and the like are used as plastics for chassis.

When the chassis is made into plastic, the plastic chassis is reinforced with a number of ribs to compensate for the lack of strength of the plastic. The shape of the chassis itself has become more complicated as the functionality of products has increased. For this reason, the shape of the chassis is complicated and the number of thin portions is increasing. The glass fiber (GF) reinforced PC resin and the GF reinforced modified PPO resin have poor fluidity and have a problem in moldability. In addition, GF reinforced ABS resin is superior to GF reinforced PC resin and GF reinforced modified PPO resin in fluidity, but the strength of the thin part and the snap fitting nail part is weak, and the heat resistance temperature is PC There is a problem that the temperature is lower than that of the resin or the modified PPO resin (the temperature of the chassis also becomes considerably high in some places). For oil resistance to various greases and oils, use PC resin or modified PP.
Neither O resin nor ABS resin was sufficient.

(Problems to be Solved by the Invention) The required characteristics of the molded chassis are the moldability, chemical resistance (oil) resistance, heat resistance, strength of the thin portion as described in the preceding section, and dimensional stability and rigidity. , Impact resistance and the like. For moldability, especially fluidity, PC resin and modified PPO
Since resin has a higher glass transition temperature than ABS resin, ABS
Unless it is molded at a considerably higher temperature than resin, the fluidity will not be improved. ABS resin has better fluidity than PC resin, but has low heat resistance temperature (low glass transition temperature)
As described above, in an amorphous resin, heat resistance and fluidity are opposite to each other.

On the other hand, a crystalline resin such as a polyamide resin or a PBT resin has a low glass transition temperature but a high melting point. Therefore, when reinforced with glass fiber, the resin has both excellent fluidity and a high heat deformation temperature. In addition, these crystalline resins are excellent in chemical (oil) resistance, strength of a thin portion, strength of a claw portion for snap fitting, particularly, bending strength. Especially chemical resistant (oil)
In terms of properties, it is much better than the non-crystalline resins ABS resin, PC resin and modified PPO resin. However,
Since the crystalline resin has a large molding shrinkage, when glass fiber is reinforced, the anisotropy of the molding shrinkage becomes large, and warpage tends to occur, resulting in poor dimensional stability. In addition, polyamide resin or PBT
Since the resin is a crystalline resin, it can not be molded at a temperature below the melting point and sharply decreases in viscosity above the melting point, and burrs are easily formed during molding, so moldability is never good in the sense that the molding temperature range is narrow. Absent. In addition, polyamide resins and PBT resins are inferior in impact resistance and paintability as compared with ABS resins, PC resins or modified PPO resins. Rigidity is determined not by the properties of the resin itself, but by the glass fiber content. However, PC resins and modified PPO resins with poor fluidity have very poor fluidity when the glass fiber content exceeds 30%, and molding is almost impossible. Can not. Therefore, when very high rigidity (for example, 100,000 or more) is required, PC resin and modified PPO resin cannot cope. As noted above,
Conventionally, crystalline resins such as ABS resin, PC resin, modified PPO resin, or polyamide resin or PBT resin were not enough to satisfy the required characteristics as a chassis molded product.

(Means for Solving the Problems) That is, the present invention relates to (A) 5 to 70 parts by weight of a rubbery polymer and an aromatic vinyl monomer
A graft copolymer obtained by grafting 30 to 95 parts by weight of a monomer mixture consisting of 40 to 80% by weight, 20 to 40% by weight of a vinyl cyanide monomer and 0 to 40% by weight of a vinyl monomer copolymerizable therewith. Polymer 20 to 80 parts by weight (B) Polyamide resin 20 to 80 parts by weight (C) Block copolymer of vinyl aromatic compound modified by grafting unsaturated carboxylic acid or its anhydride with conjugated diene It is characterized by being formed from a resin composition comprising 5 to 30 parts by weight of a hydrogenated product (however, (A) + (B) + (C) = 100 parts by weight).
It is a molded chassis for OA and home appliances.

The graft copolymer used in the present invention generally means a conjugated diene rubber-aromatic vinyl-vinyl cyanide graft copolymer alone or an aromatic vinyl-vinyl cyanide copolymer of 90% by weight or less. It may be prepared by any polymerization method such as emulsification, bulk suspension or continuous bulk.

Here, the conjugated diene rubber-aromatic vinyl-vinyl cyanide graft copolymer is a graft polymer obtained by graft-polymerizing a rubbery polymer containing a conjugated diene as an essential component and an aromatic vinyl compound and vinyl cyanide as essential components. It is a polymer. The composition ratio of the rubbery polymer in the graft polymer and the monomer mixture for graft polymerization is 5 to 70 in the rubbery polymer.
% By weight and 30 to 95% by weight of a monomer mixture for graft polymerization
It is. When the content of the rubbery polymer component is less than 5 parts by weight, the impact resistance of the final blend composition becomes poor, and
If it exceeds 70 parts by weight, the heat resistance of the final composition does not increase.
Further, the graft polymerization monomer mixture may contain a vinyl monomer copolymerizable therewith in addition to the aromatic vinyl monomer vinyl cyanide monomer. The composition ratio of these monomers is 40 to 80% by weight of an aromatic vinyl monomer and 20 to 40% by weight of a vinyl cyanide monomer, and 0 to 40% by weight of a vinyl monomer copolymerizable therewith. is there. If the content of the vinyl cyanide monomer is less than 20% by weight, the impact resistance of the final blend composition is poor, and if it exceeds 40% by weight, the thermal stability of the graft copolymer is reduced.

The limiting viscosity of the aromatic vinyl-vinyl cyanide copolymer (measured in methyl ethyl ketone at 30 ° C.) is also 0.20 to less.
A range of 0.75 is preferred.

Examples of the graft copolymer or the conjugated diene rubber in the copolymer include butadiene rubber-like polymers such as polybutadiene, butadiene-acrylonitrile copolymer, and butadiene-acrylate copolymer. As aromatic vinyl, styrene,
Halogenated styrene, vinyltoluene, vinylnaphthalene, etc. are indicated, and styrene is particularly preferable. As vinyl cyanide, acrylonitrile, methacrylonitrile, α
-Halogenated acrylonitrile and the like, particularly,
Acrylonitrile is good. Examples of vinyl monomers copolymerizable with aromatic vinyl and vinyl cyanide include (meth) acrylic esters, vinyl acetate, vinyl chloride, and acrylamide, and particularly (meth) acrylic esters Are preferred.

The polyamide resin used in the present invention is a polycondensate of a diamine and a dibasic acid, a self-condensate of an ω-aminocarboxylic acid, a ring-opening polymer of a cyclic lactam, and the like. Specific examples include nylon-6, Fatty acids such as aliphatic polyamides such as 6, nylon-6, nylon-4,6, nylon 6,10, nylon-11, and nylon-12, polyhexamethylene terephthalamide, polyhexamethylene isophthalamide, and polytetramethylene isophthalamide Aromatic-aromatic polyamides and their copolymers and mixtures can be used. Of these, nylon-6, nylon-6,6 are preferably used, and nylon-6 is more preferably used.

The relative viscosity of the polyamide used (measured in 96% sulfuric acid at 25 ° C.) is preferably in the range of 1.8 to 6.8.

As the above-mentioned polyamide, those manufactured by a well-known manufacturing method are used. Usually, it can be produced by an equimolar polycondensation reaction of a diamine and a dicarboxylic acid, a self-condensation reaction of an aminocarboxylic acid, or a ring-opening polymerization of a lactam.

The hydrogenated product of the block copolymer of a vinyl aromatic compound and a conjugated diene modified by grafting an unsaturated carboxylic acid or an anhydride thereof used in the present invention is a vinyl aromatic compound polymer block A and an olefin compound. A copolymer comprising a polymer block B and an unsaturated degree
A hydrogenated block copolymer elastomer not exceeding 20%, which has a functional group obtained by a graft reaction with an α, β-unsaturated carboxylic acid compound having a carboxylic acid or an acid anhydride group in the presence of a radical initiator. It is a hydrogenated block copolymer contained.

The hydrogenated block copolymer component in the hydrogenated block copolymer modified by grafting an unsaturated carboxylic acid or its anhydride is composed of a vinyl aromatic compound polymer block and a conjugated diene compound polymer block. Obtained by selectively hydrogenating the conjugated diene portion of the resulting block copolymer.

The block copolymer comprising the vinyl aromatic compound polymer block and the conjugated diene compound polymer block is a vinyl aromatic compound polymer block (X) and (X ′) and a conjugated diene compound polymer block ( Y)
(However, X and X 'may be the same or different.)
A block copolymer consisting of (XY) _n , XYX ′,
X- (Y-XY) _n- X, X- (YX) _n- Y, where n
Is an integer of 1 to 10. ) Or a general formula [(YX) _n ] _{m + 2-} Z, [(XY) _n ] _{m + 2-} Z,
[(Y−X) _n −Y] _{m + 2} −Z, [(XY) _n −X] _{m + 2} −Z, where m is 1 to 4
And Z represents a residue of a coupling agent such as silicon tetrachloride or tin tetrachloride, or a residue of an initiator such as a polyfunctional organic lithium compound. )).

Typical examples of the vinyl aromatic compound used here include styrene, α-methylstyrene, vinylxylene, ethylvinylxylene, vinylnaphthalene and a mixture thereof, and a conjugated diene compound polymer includes , Butadiene, isoprene, 1,3-pentadiene or 2,3-dimethylbutadiene and mixtures thereof.

The terminal blocks of these block copolymers may be the same or different.

The number average molecular weight of these block copolymers is 10,000-
800,000, preferably 20,000-500,000.

The content of the vinyl aromatic compound in the block copolymer is preferably from 10 to 70% by weight, more preferably from 10 to 55% by weight.
% By weight. The hydrogenated block copolymer used in the present invention is obtained by selectively hydrogenating the conjugated diene portion of the block copolymer, for example,
By hydrogenating the block copolymer by the method described in JP-B-42-8704, a portion not exceeding 20% of the aromatic double bond of the vinyl aromatic compound block and the conjugated diene compound polymer block are obtained. Hydrogenated block copolymers in which at least 80% of the aliphatic double bonds have been hydrogenated have been synthesized.

The degree of unsaturation of the block (Y) in the present invention means the ratio of carbon-carbon double bonds contained in the block (Y), and is usually within a range not exceeding 20%. This is measured by instrumental analysis such as nuclear magnetic resonance spectrum (NMR) and infrared absorption spectrum (1R), and chemical analysis such as iodine titration.

These hydrogenated block copolymers can be used alone or in combination of two or more.

Specific examples of the α, β-unsaturated carboxylic acid compound having a carboxylic acid or acid anhydride group to be graft-reacted with the hydrogenated block copolymer include maleic anhydride, maleic acid, itaconic anhydride, fumaric acid, and methyl anhydride. Nadic acid, dichloromaleic anhydride, acrylic acid, methacrylic acid and the like.

The radical initiator used in the Kraft reaction represents a known organic peroxide or diazo compound, and specific examples include benzoyl peroxide, dicumyl peroxide, t-butyl hydroperoxide, cumene hydroperoxide, Azobisisobutyronitrile and the like can be mentioned. These radical initiators can be used in combination of two or more.

The method for producing the hydrogenated block copolymer modified by grafting the unsaturated carboxylic acid or anhydride thereof of the present invention is not particularly limited in the present invention, but the melt viscosity of the obtained copolymer is remarkable. A manufacturing method in which the workability increases and the workability deteriorates is not preferable. A preferred method is a method in which a hydrogenated block copolymer and an unsaturated carboxylic acid or its anhydride are subjected to a graft reaction in an extruder in the presence of a radical initiator.

The addition amount of the α, β-unsaturated carboxylic acid compound having a carboxylic acid or acid anhydride group to the hydrogenated block copolymer is preferably 0.05 to 10 parts by weight per 100 parts by weight of the hydrogenated block copolymer, and Is more preferably 0.1 to 5 parts by weight. When the addition amount is less than 0.05 part by weight, the effect is small as a hydrogenated block copolymer modified by grafting an unsaturated carboxylic acid or its anhydride, and when the composition is used, sufficient impact resistance is obtained. Absent. Further, even if the added amount exceeds 10 parts by weight, the effect of the modification is hardly increased as compared with the amount less than 10 parts by weight.

The molded article of the present invention is mainly formed from the following composition.

A resin composition comprising (A) a graft copolymer, (B) a polyamide and (C) a hydrogenated block copolymer modified by grafting an unsaturated carboxylic acid or an anhydride thereof. The mixing ratio of these components is (A)
(A) 20 to 80 parts by weight of graft copolymer (B) 20 to 80 parts by weight of polyamide resin (C) Modified hydrogenated block with respect to 100 parts by weight of total of component, component (B) and component (C) The copolymer is 5 to 30 parts by weight.

(A) If the amount of the graft copolymer is less than 20 parts by weight, the impact resistance, dimensional stability and paintability of the molded product are not sufficient, and the
Exceeding parts by weight, the chemical resistance and heat resistance of the molded product are poor,
(B) If the polyamide resin content is less than 20 parts by weight, the chemical resistance and heat resistance of the molded article are not sufficient, while if it exceeds 80 parts by weight, the dimensional stability of the molded article is poor. (C) If the modified hydrogenated block copolymer is less than 5 parts by weight, the impact resistance of the molded article is low.
If it exceeds 30 parts by weight, the heat resistance of the molded product is low and the cost is high.

The molded articles of the present invention include inorganic fillers, nucleating agents, flame retardants,
A release agent, a lubricant, an antistatic agent, a coloring agent, and the like may be included.

Among these additives, particularly as an inorganic filler,
Glass fiber, glass flake, glass beads, talc,
There are quartz, mica, calcium silicate, titanium dioxide and the like, and particularly preferred is glass fiber. The amount of the component added is a total of 100 components (A), (B) and (C).
If the amount exceeds 100 parts by weight with respect to the parts by weight, the fluidity at the time of molding is undesirably reduced.

The OA in the present invention is a typical home appliance such as a printer, a facsimile, a copier, a radio-cassette, a video tape recorder, a video camera, a video disc player, a compact disc player, a word processor, a calculator, a telephone, an electromagnetic cooker, and the like. Yes, these are chassis moldings of these devices.

(Examples) Hereinafter, the present invention will be described with reference to examples.

Example 1, Comparative Example 1 Graft copolymer (52.5% by weight of styrene, 17.5% by weight of acrylonitrile, 30% by weight of polybutadiene), polyamide resin (Nylon 6, A1030BRL manufactured by Unitika Ltd.), unsaturated carboxylic acid or anhydride thereof A hydrogenated block copolymer modified by grafting (styrene 28% by weight, rubber 72% by weight, maleic anhydride addition rate 2% by weight) and glass fiber were mixed at a ratio of 45: 45: 10: 25. And kneaded and extruded with a 40 mmφ extruder to form pellets. Using the pellets, molded pieces (5 ″ × 1/2 ″ × 1/8 ″) were prepared by an injection molding machine and evaluated for oil resistance, and the results are shown in Table 1.
The evaluation method is such that a test piece is given a strain amount corresponding to 30% of the maximum bending stress, a chemical is applied to the convex part of the test piece, left at 70 ° C. for 7 days, and the strength retention and appearance are evaluated. As a comparative example, the results of a modified PPO resin (GF 20%) are also shown.
It can be seen that the molded article of the present invention has excellent oil resistance.

Example 2, Comparative Example 2 Using the pellets produced in Example 1, a printer chassis having a shape as shown in FIG. 1 was molded. As Comparative Example 2, the printer chassis of FIG. 1 was molded from a polyamide (containing 20% GF) resin, and the molding shrinkage was similarly shown in Table 2.
In the product of the present invention, the variation in the molding shrinkage is significantly reduced as compared with the polyamide resin molded product.

Example 3 and Comparative Example 3 A test piece was prepared by injection molding using the pellets prepared in Example 1, and the coating property was evaluated. Table 3 shows the coating conditions.
Table 4 shows the evaluation method. The paint used was Planet SV and Planet PX-8 (both made by Origin Electric Co., Ltd.)
It is. Table 5 shows the evaluation results.

As Comparative Example 3, a polyamide (containing 20% GF) resin molded product was similarly evaluated, and the results are shown in Table 5.

(Effects of the Invention) The molded article of the present invention has much better chemical resistance (oil) resistance such as oil resistance, grease resistance and solvent resistance than molded articles made of amorphous resin, and has heat resistance and paintability. Also, it has excellent impact resistance and has greatly improved warpage, which is a disadvantage of crystalline resins, and exhibits excellent dimensional stability.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of a molded product of a printer chassis used in Example 2. FIG. 2A is a top view of the printer chassis. FIG. 2B is a side view of the printer chassis. The mold dimensions are A = 250mm, B = C = D = 110mm, E = 70mm

Claims (1)

(57) [Claims] 1. A rubber-based polymer (A) comprising 5-70 parts by weight of an aromatic vinyl monomer at 40-80% by weight and a vinyl cyanide monomer at 20-80% by weight.
40% by weight and a vinyl monomer copolymerizable therewith
Graft copolymer obtained by grafting 30 to 95 parts by weight of a monomer mixture consisting of 40% by weight 20 to 80 parts by weight (B) Polyamide resin 20 to 80 parts by weight (C) Unsaturated carboxylic acid or its anhydride is grafted 5 to 30 parts by weight of a hydrogenated product of a block copolymer of a vinyl aromatic compound and a conjugated diene modified by the above method (provided that (A) + (B) + (C) = 100 parts by weight) ) Characterized by being molded with a resin composition
OA, molded products for home appliances.