JPS6364468B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a polyacetal resin molded article having novel surface properties particularly suitable for surface decoration by printing, painting, metal vapor deposition, etc., adhesion with adhesives, surface coating such as metal plating, etc. In general, plastics, especially polyacetal resins, are chemically stable and the surface of molded products made by injection molding etc. is smooth, so they have poor surface activity, and can be used for surface decoration by printing, painting, vapor deposition, adhesion with adhesives, metal plating, etc. surface coating is difficult to apply. Several attempts have been made to improve the surface coverage of these materials. For example, there is a method of treating the surface of the molded product with phosphoric acid, a method of treating it with chromium sulfuric acid, etc.
No. 19876, etc.). However, the surface properties of polyacetal resin molded products obtained by implementing these treatment methods also
It cannot be said that it is sufficiently suitable for the above-mentioned surface decoration and surface coating, and, for example, it has not been possible to provide a metal-plated product with a beautiful appearance and high plating peel strength. Subsequently, as an improved invention of the above-mentioned US Pat. No. 3,554,880, for the purpose of more uniform surface roughening, a method of immersing the molded product surface in an aqueous solution of pyridine, quinoline, γ-butyrolactone, etc. as a pre-process of treating the surface with phosphoric acid. has been found (U.S. Patent No.
3905877, 3963590). However, when surface roughening a polyacetal resin molded product, such as metal plating, it is still not possible to achieve a uniform surface roughness industrially that is sufficient for practical use using the above-mentioned conventional techniques. Non-uniform roughening phenomenon can be seen in each location of the product, which is thought to be mainly due to variations in wall thickness. This uneven roughening phenomenon is a problem that leads to "blistering" in areas where roughening is insufficient, for example, in heat cycle tests of plated products. Therefore, in order to obtain a good plated product, there is a need for a method that further improves the level of plating adhesion and its uniformity, and that can be easily implemented industrially. The present inventors have developed a molded product with excellent plating adhesion and uniformity without requiring a simpler process than the method disclosed in US Pat. No. 3,905,877 and US Pat. We have discovered a polyacetal resin composition that provides the following properties. That is, the present invention provides (a) polyacetal resin
100 parts by weight, (b) 0 to 35 parts by weight of carbonates, phosphates, acetates or mixtures thereof of metals of Group Group of the Periodic Table, (c) unsaturated polyesters, alkyl esters of acrylic acid or methacrylic acid, acrylics. 0.01 to 20 parts by weight of a polymer, copolymer or mixture thereof of a compound selected from the group of acids or amides of methacrylic acid, triallyl cyanurate, diallyl phthalate, vinyl acetate and divinylbenzene, and (d) as described in the specification. In the ¹³ CNMR of acetic acid measured by ^the method of
A nitrogen-containing heterocyclic compound that has the property of chemically shifting the spectral position of
The present invention relates to a polyacetal resin composition containing up to 0.5 parts by weight and having excellent surface decoration properties. In the present invention, it is more preferable for the polyacetal resin to contain various salts of group metals of the periodic table, and the purpose thereof is to more easily form a more complex roughened surface suitable for surface processing. In other words, when various salts of Group Group metals of the periodic table are dispersed and dotted in the polyacetal continuous phase, they are easily decomposed and removed by an appropriate acid, leaving traces as a roughened surface. Among the various salts of Group Group metals of the periodic table used in the present invention, examples of preferable carbonates include calcium carbonate, magnesium carbonate, zinc carbonate, barium carbonate, and the like, with calcium carbonate being the most preferable. In addition, when the above-mentioned various salts are included, the content should be 2 to 35 parts by weight based on 100 parts by weight of the polyacetal resin, taking into consideration the balance between the effect of improving roughening properties and the decrease in mechanical properties and thermal stability. It is preferable that there be. In the present invention, the above-mentioned polyester such as unsaturated polyester
The purpose of containing component (c) is to improve the thermal stability of the resin composition and to prevent cracking during surface roughening. The amount added is preferably 0.01 to 20 parts by weight based on 100 parts by weight of the polyacetal resin, considering the desired effect and the balance with the mechanical strength of the resin. In the present invention, the purpose of containing component (d) is to make the roughening state of each part of the molded product uniform. Whether or not a compound falls under component (d) having this effect can be determined by the following method. (1) Take the ¹³ C spectrum of acetic acid alone and measure the spectral position of ¹³ C in the carbonyl group. (2) Next, mix equimolar amounts of the compound and acetic acid (usually at nitrogen temperature, with heating for substances that are difficult to dissolve), take a ¹³ C NMR spectrum under the same conditions as in (1), and calculate the chemical shift amount ( Preferably, dioxane is used as the internal standard). (3) From the results of (1) and (2) above, the carbonyl group of acetic acid
When the spectral position of ¹³ C shifts to the lower magnetic field side in the presence of a compound, that compound is a nitrogen-containing heterocyclic compound that corresponds to the component (d) compound of the present invention. Examples of nitrogen-containing heterocyclic compounds corresponding to component (d) of the present invention include pyridine, quinoline, isoquinoline, 2-aminopyridine, 3-hydroxypyridine, 3-pyridinemethanol, pyridine-4-aldehyde, -Pyridine ethanol, nicotinic acid methyl ester, nicotinic acid ethyl ester, isonicotinic acid methyl ester, 4
- Phenylpyridine, etc. Particularly preferred among these are 3-hydroxypyridine, 3-pyridinemethanol, 2-pyridineethanol, and the like.
The measurement results for some examples are shown in Table A. The amount of these compounds added is 0.01 to 0.5 parts by weight, more preferably 0.02 to 0.2 parts by weight per 100 parts by weight of the polyacetal resin, considering the balance of effects and thermal stability.
Parts by weight.

[Table] The polyacetal resin used in the present invention may be a homopolymer, that is, a polymer obtained by polymerizing formaldehyde or trioxane (including those whose terminals have been stabilized), or a polymer obtained by polymerizing formaldehyde or trioxane, or a polymer obtained by polymerizing formaldehyde or trioxane. It may be a binary, ternary or more copolymer obtained by copolymerizing comonomers such as ether or cyclic acetal. The composition of the present invention includes various additives normally added to polyacetal resins, such as heat stabilizers, antioxidants, ultraviolet absorbers, antistatic agents, crystal nucleating agents,
There is no problem even if pigments are added. In order to obtain the composition of the present invention, it is preferable to mix the constituent components using a device, such as a kneader, roll mill, or extruder, which is normally used for kneading resin melts. An extruder is most preferable from the viewpoint of blocking oxygen and working environment. The mixing temperature is above the melting point of the polyacetal resin used. This is determined by the need to uniformly mix the polyacetal resin in its molten state. The upper temperature limit is generally limited by the thermal decomposition stability of the polyacetal resin used;
Mixing is usually carried out at a temperature below 250°C, preferably below 230°C. Polymers such as unsaturated polyesters for thermal stability and crack prevention may be mixed directly as polymers, or may be added in the form of monomers or prepolymers and polymerized in an extruder. In the case of thermosetting polymers, the latter is preferred. In addition, it is preferable to premix the constituent components in advance using a tumbler or Henschel mixer, etc. in order to make a homogeneous composition, and it is preferable to use the polyacetal resin in a powdered state for stable supply to the extruder. Although preferred, these are not required. In addition, in the case of the method of adding the above-mentioned monomer or prepolymer, it is preferable to maintain a temperature at which a polymerization reaction does not occur during premixing. In the case of the above method of adding monomers or prepolymers, the heating conditions for polymerizing them are, for example, 190°C x 1 to 10 minutes, depending on the type of monomer or prepolymer. It is.
This condition can be achieved in most cases by the typical temperature and time combinations (determined by the extrusion speed) used when mixing polyacetal resin compositions using conventional extruders, or by other auxiliary heating means. However, the present invention does not impose any limitations on the heating method itself. Further, a polymerization initiator may be added to the composition. There are various ways to confirm that the polymerization of the added monomer or prepolymer has been completed by the above heating and that no unreacted materials remain. In addition, there are methods to confirm by immersing pellets in a solvent and checking whether unreacted substances are extracted using infrared spectrophotometry. In addition, as for the mixing method of the above-mentioned (d) component, the above-mentioned (a),
It was confirmed that dry blending into pellets consisting only of components (b) and (c) had similar effects. From an industrial perspective, this means that, depending on the shape of the molded product, it is possible to dry blend the required amount immediately before injection molding. In the case of dry blending, it is preferable not only to mix the compounds alone, but also to blend them together with a volatile solvent and then volatilize only the solvent. In the case of solid compounds, it is also preferable to heat them to their melting point (heating the pellets as well) and dry blend them in the molten state. The polyacetal resin composition of the present invention produced by the above method is usually made into a molded product using an injection molding machine (an extruder or other machine may be used depending on the shape of the molded product), and then the molded product is further molded with an appropriate acid. and is etched. As a result, a polyacetal resin molded product having the desired excellent surface workability can be obtained. Suitable acids for use in etching the polyacetal resin composition of the present invention include any acidic or oxidizing liquid that can decompose the various salts of Group Group metals of the periodic table blended as described above. However, it is preferable to use less volatile acidic or oxidizing liquids, such as aqueous sulfuric acid solution, sulfuric acid-
A mixed aqueous solution of phosphoric acid, a mixed aqueous solution of sulfuric acid and chromic acid, an aqueous phosphoric acid solution, and the like are preferred from the viewpoint of workability. The thus etched polyacetal resin molded product with excellent surface workability has a peel strength (Kg/cm) of the plating layer of 1Kg/cm when plated with metal.
cm or more, usually 1.0 to 2.0 Kg/cm, and has a uniform adhesion force to each part of the molded product, and also shows surprising effects when bonding with paints other than metal plating and adhesives.
This shows how useful the polyacetal resin composition of the present invention is. The present invention will be explained in more detail below with reference to Examples. Examples 1 to 5 and Comparative Example 1 "Tenatsuku 5010" as polyacetal resin
(Manufactured by Asahi Kasei Corporation, acetal homopolymer,
General grade) 100 parts by weight, 8.7 parts by weight of finely powdered calcium carbonate (Whiten SSB Red, manufactured by Shiraishi Calcium Co., Ltd., average particle size 1.25 microns) and unsaturated polyester (Yupica CLC)
834 (manufactured by Toyobo Co., Ltd.) were mixed in a tumbler and kneaded in an extruder set at 190°C to form pellets. The pellets were dry-blended with the compounds shown in Table 1, and an inner handle for an automobile was made by injection molding, which was used as a test material. This flat plate was degreased at 60°C for 2 minutes using an ordinary alkaline degreaser, and the mixture was heated to 96% sulfuric acid / 85% phosphoric acid / water = 40 /
Etching was performed by immersing it in a solution consisting of 25/35 (weight ratio) at 40°C for 8 minutes. Next, the etched flat plate was plated using a conventional method. First, it is immersed in pre-treatment liquid for plastic plating (manufactured by Okuno Pharmaceutical Co., Ltd., Catalyst) and accelerator (10% hydrochloric acid aqueous solution) for a specified time, and then treated with a chemical plating liquid (manufactured by Okuno Pharmaceutical Co., Ltd., TMP chemical nickel plating liquid). It was chemically plated using the method described above and immediately subjected to electroplating. The average plating film thickness was 40μ for copper, 10μ for nickel, and 0.1μ for chrome. In this way, plating was applied. The performance of the plated material was as shown in Table 1. The plating performance was measured using the following method. (1) Peeling strength of plated products: Make parallel cuts of 10 mm width on the plated surface, pull the plated film between the cuts in a direction perpendicular to the flat plate surface, and calculate the stress required for peeling. A and B in Table 1 indicate the upper part of the rib (thick wall part) A○ and the part other than the rib (thin wall part) B○ of the automobile inner handle shown in the schematic perspective view of FIG. 1 (see Table 2). The same goes for A and B).

[Table] Examples 6 to 8 The compounds listed in Table 1 in Examples 1, 2, and 3 were kneaded together with other components in an extruder without dry blending to produce pellets. The same experiments as in Examples 1, 2 and 3 were carried out below, and the results shown in Table 2 were obtained.

【table】 [Brief explanation of drawings]

FIG. 1 shows a schematic perspective view of a plated inner handle for an automobile used in an example.

Claims (1)

[Scope of Claims] 1 (a) 100 parts by weight of polyacetal resin, (b) 0 to 35 parts by weight of carbonate, phosphate, acetate or a mixture thereof of a group metal of the periodic table, (c) unsaturated Polymers, copolymers or mixtures thereof of compounds selected from the group of polyesters, alkyl esters of acrylic acid or methacrylic acid, amides of acrylic acid or methacrylic acid, triallyl cyanurate, diallyl phthalate, vinyl acetate and divinylbenzene0.01 ~20 parts by weight, and (d) has the property of chemically shifting the spectral position of ¹³ C in the carbonyl group to the lower magnetic field side in ¹³ C nuclear magnetic resonance (NMR) of acetic acid, measured by the method described in the specification. , 0.01-0.5 nitrogen-containing heterocyclic compounds
A polyacetal resin composition with excellent surface decoration properties, consisting of parts by weight. 2 (d) component is kneaded and formed in advance (a), (b)
and the polyacetal resin composition according to claim 1, which is obtained by dry blending the pellets comprising component (c). 3. Claim 1 obtained by simultaneously kneading and molding components (a), (b), (c) and (d) into pellets.
The polyacetal resin composition described in .