JP4750375B2 - Chemical finishing film finishing agent and finishing treatment method - Google Patents

Description

  More particularly, the present invention relates to a finishing agent and a finishing method for fastening parts such as bolts, washers and nuts that have been subjected to a chemical coating treatment.

  The chemical film treatment is a surface treatment that combines functional effects such as rust prevention, decoration, and sliding. Mainly galvanized or zinc-based alloy plated (hereinafter referred to as galvanized) is applied on iron-based parts. Done later. Among the chemical conversion film treatments, chromate treatment using hexavalent chromium is generally widely used because it is inexpensive, excellent in functional effect, and easy to treat. Recently, however, we have developed chemical coatings (= trivalent chromium conversion coatings) whose valence has been changed from hexavalent chromium to trivalent chromium in consideration of the environment, and chemical coatings that do not use chromium elements (= chromium-free conversion coatings). It has been broken.

  Even after chemical conversion film treatment such as chromate treatment is applied on galvanizing, anti-corrosion effect, decoration effect, and the effect of preventing damage even if parts hit each other by working as protective film Often, these chemical conversion films are further covered with an organic film based on an acrylic resin or an epoxy resin, or an inorganic film based on a silicon compound typified by water glass. This treatment is commonly referred to as a topcoat or overcoat in the galvanizing industry. For example, Japanese Patent No. 3332373 describes a top coat treatment for a chemical conversion film using trivalent chromium.

Japanese Patent No. 3332373

  However, since the top coat naturally reflects the slipperiness of these top coats, the friction coefficient when bolts, washers, nuts, etc. are fastened cannot be adjusted to an appropriate value. Further, if the adhesion between the top coat and the chemical conversion film is not good, naturally, the effects of rust prevention and decoration cannot be obtained, so the concentration of the top coat agent needs to be increased. However, when the concentration is increased, there is a possibility that problems such as a longer drying time and a tendency to cause liquid pooling are caused.

  In addition, when the top coat treatment is usually introduced into the galvanizing process, the conversion coating treatment, water washing, top coat treatment, and drying are carried out in this order. A water draining process is provided between the top coats and a liquid draining process for removing excess top coat agent is provided between the top coat process and drying to make the top coat uniform and reduce the accumulation. Furthermore, the top coat treatment and the drying are performed a plurality of times, and there is a problem that it takes time and effort. In particular, when the top coat is dried, the top coat agent partially accumulates and may be dried or remain as traces of flow stains. Therefore, depending on the shape of the object, the overcoat process itself may be difficult.

  Therefore, an object of the present invention is to solve the above problems. In particular, a finishing agent and a finishing method that can adjust the coefficient of friction when fastening parts such as bolts, washers, and nuts are fastened, and prevent the parts from being damaged even if they hit each other. The purpose is to provide.

  In order to solve the above-mentioned problems, the present inventors have commonly adjusted the coefficient of friction when fastening parts such as bolts, washers and nuts, and also prevent parts from hitting each other and scratching each other. In view of the above, it was considered that even if a thick layer such as a top coat was not formed, the same effect could be obtained by fixing finely divided substances on the chemical conversion film.

  In order to immobilize the fine particulate material on the chemical conversion film, it is necessary that the fine particulate material is bonded to the chemical conversion film by a chemical reaction or physical strong adsorption occurs. As a result of intensive studies, the inventors have found that some types of polyolefin aggregate and float on the acidic side. Since the surface of the chemical conversion film produced from the acidic chemical conversion film treatment solution shows the acidic side even after washing with water, if the article subjected to the chemical conversion film treatment is immersed in an aqueous solution in which this polyolefin is dispersed, It was presumed that the agglomerated and fixed polyolefin could be fixed firmly by agglomerating and fixing, and the chemical conversion film being stabilized. The treatment according to the present invention is called a finishing treatment to distinguish it from the top coat treatment used in the prior art, and the treatment agent used in the present invention is called a finishing agent.

The present invention thus completed is an invention having the following features.
That is, the present invention is a finish for a chemical conversion film characterized by containing a polyolefin.

  In one embodiment of the present invention, the polyolefin is a polyolefin having a property of aggregating on the acidic side.

  In one embodiment of the invention, the polyolefin is finely divided.

  In one embodiment of the present invention, the finely divided polyolefin has an average particle size of 0.001 to 20 μm.

  In one embodiment, the finishing agent of the present invention includes at least one of polyethylene and polypropylene as the polyolefin.

  In one embodiment of the invention, the finish has a pH of 6-11.

In one embodiment, the finishing agent of the present invention is a low molecular weight polyethylene having a weight average molecular weight of 500 to 10,000, a low molecular weight polypropylene having a weight average molecular weight of 500 to 10,000, a low density polyolefin having a density of 800 to 1000 kg / m ³ , a heat At least one polyolefin selected from the group consisting of a plastic elastomer and a copolymer resin with vinyl acetate is included.

  One embodiment of the finish of the present invention comprises at least one of a modified polyolefin obtained by reacting a polyolefin with an unsaturated carboxylic acid or an anhydride thereof, and a polyolefin converted into an ionomer.

  In one embodiment of the present invention, the chemical conversion film is generated from a treatment liquid not containing hexavalent chromium having a pH of 0.1 to 6.5.

  In one embodiment of the invention, the concentration of the polyolefin is 0.001 to 50 g / L.

  In one embodiment, the finishing agent of the present invention is used for finishing processing of a fastening part, and a fastening part subjected to finishing processing using the finishing agent is also included in another embodiment of the present invention.

  In one embodiment of the present invention, the chemical conversion film is a chemical conversion film applied to the surface of an iron part that has been subjected to zinc or zinc alloy plating. It is included in the embodiment.

  In one embodiment, the present invention is a chemical conversion film finishing method comprising a step of agglomerating and fixing finely divided polyolefin on a chemical conversion film.

Since the present invention is as described above, the following effects can be obtained.
That is, by changing the concentration of polyolefin in the finishing agent according to the present invention, the amount of polyolefin aggregated on the chemical conversion film changes, and the coefficient of friction when fastening parts such as bolts, washers and nuts are fastened accordingly. Can be changed. Since the friction coefficient does not depend on its own slipperiness like a top coat, the friction coefficient can be easily adjusted to an appropriate value by changing the type and concentration of the polyolefin used. Further, even if the parts hit each other, they can be prevented from being damaged, and the corrosion resistance can be improved.
And since the concentration of the finely divided polyolefin used is generally lower than that of the overcoat agent, the finisher does not accumulate partially during drying and does not remain as traces of flow stains. The shape of the object is greatly expanded.
Furthermore, after the chemical conversion film treatment, it can be constituted by simple treatment steps of washing with water, finishing treatment, and drying, so that the treatment can be performed in a shorter time than the top coat treatment.

  Each configuration of the above means will be described in detail.

In the present invention, any polyolefin can be used, but a polyolefin having a property of aggregating on the acidic side is preferred. Polyethylene or polypropylene is used for such polyolefin. The types of polyolefin include, but are not limited to, those having a low molecular weight, those having a density of 800 to 1000 kg / m ³ , thermoplastic elastomers, and copolymers with vinyl acetate. As a low molecular weight polyethylene having a weight average molecular weight of 500 to 10000, preferably about 1000 to 6000, a low molecular weight polypropylene having a weight average molecular weight of 500 to 10000, preferably about 1000 to 6000, a density of about 850 to 1000 kg / m ³ Examples include density polyethylene, a thermoplastic elastomer that draws out the elastic force of polyethylene, and an ethylene vinyl acetate copolymer resin obtained by polymerizing a vinyl acetate group on polyethylene.

  There are sheets, pellets, fine particles and the like in the shape of polyolefin, but fine particles are preferable for aggregation and fixation on the chemical conversion film, and spherical shapes are more preferable. The particle size of the finely divided polyolefin is about 0.001 to 20 μm, and the particle size distribution is centered on a certain particle size, but the average particle size is preferably 0.001 to 20 μm, more preferably 0.005 to 15 μm. Preferably, 0.01-12 micrometers is the most preferable. The average particle diameter can be measured by a Coulter counter method.

Since finely divided polyolefin has a lower density than water, it floats even if mixed with water and is difficult to disperse. In order to disperse such a polyolefin in water, the polyolefin is modified by reacting with an unsaturated carboxylic acid or an anhydride thereof such as acrylic acid, methacrylic acid, maleic acid, fumaric acid, maleic anhydride, citraconic anhydride, etc. A method of making a polyolefin and adding a small amount to the polyolefin to be dispersed and mixing it, or a hydrophobic polymer polyolefin partially modified with an organic substance having a carboxyl group or a sulfone group, etc. There is a method in which an ionic polymer neutralized with ions or the like, so-called ionomer, can be dispersed in water by itself.
In addition to water, a water-soluble organic compound such as alcohol can be used as the solvent for dispersing the polyolefin, but it is preferable to use water in consideration of the influence on the environment.

  Commercially available fine-grained polyethylene includes Sumitomo Seika's Flowsen series, Nihon Unicar's PES series, Asahi Kasei's Sunfine LH and Sunfine SH, and Honeywell, USA ACumist series, and Chemipearl series manufactured by Mitsui Chemicals, Inc. Microparticulate polypropylene includes the Flowbren series manufactured by Sumitomo Seika Co., Ltd. and the Chemipearl series manufactured by Mitsui Chemicals, Inc. (named above). The polyolefin used in the present invention is preferably the aforementioned Chemipearl series manufactured by Mitsui Chemicals.

  The density | concentration of polyolefin is represented by solid content density | concentration, and is 0.001-50 g / L, Preferably it is 0.005-30 g / L, Most preferably, it is 0.01-20 g / L. If the concentration is too high, the polyolefin falls off from the surface of the chemical conversion film and powder is blown. Conversely, if the concentration is too low, the slippage becomes worse.

  The pH of the aqueous solution (finishing agent) in which the finely divided polyolefin is dispersed is 6 to 11, preferably 6.5 to 10.5, and most preferably 7 to 10. If the pH deviates from these ranges, it is not preferable because the polyolefins on the fine particles aggregate. In order to adjust the optimum pH, for example, caustic alkali such as lithium hydroxide, sodium hydroxide, potassium hydroxide, ammonia water, amine compound such as triethanolamine, tetramethylammonium hydroxide, triethanolamine, trisodium phosphate Inorganic acid salts such as sodium acetate, organic acid salts such as sodium acetate, inorganic acids such as sulfuric acid, nitric acid, hydrochloric acid and phosphoric acid, and organic acids such as acetic acid and tartaric acid can be used.

  The temperature of the finishing agent is preferably 0 to 60 ° C, more preferably 10 to 40 ° C, and most preferably 10 to 30 ° C. The treatment time is preferably 1 to 60 seconds, more preferably 2 to 30 seconds, and most preferably 5 to 20 seconds. There are dipping, coating, spraying, etc. as finishing methods, and these may be used alone or in combination depending on the shape of the object.

  Drying after taking out from the finishing agent is preferably carried out by centrifugal drying or blow drying from the viewpoint of mass production, and the drying time is preferably 1 to 20 minutes, more preferably 3 to 15 minutes. Even if the drying time is too long, there is no damage to the film, but the productivity is lowered. On the other hand, if it is too short, drying of the film will be insufficient, and the polyolefin will be insufficiently fixed and the slipperiness will not be stable. The drying temperature is 30 to 120 ° C., preferably 40 to 100 ° C. after the part is taken out from the finishing agent treatment liquid.

Although the chemical conversion film which can use this invention is not specifically limited, It can use preferably for the trivalent chromium chemical conversion film applied on zinc. The pH of the treatment liquid for forming the chemical conversion film is preferably 0.5 to 6.5, more preferably 1 to 6, and most preferably 1.4 to 5.0. For example, as the chemical conversion film, those described in Japanese Patent No. 3392008 and Japanese Patent No. 3332373 can be used, and as the chromium-free chemical conversion film, for example, those described in JP-A-9-53192 can be used. . The color tone of the chemical conversion film is generally classified into colorless, colored, black and the like, but is not particularly limited to this classification.
As means for performing the chemical conversion film treatment, for example, any one of dipping, coating, and spraying can be used alone or in combination.
The water washing after the chemical conversion film treatment can be performed by dipping or spraying.

  Objects to which the conversion coating capable of finishing according to the present invention is applied include, but are not limited to, zinc, copper, nickel, silver, iron, cadmium, aluminum, magnesium, and alloys thereof. These may be subjected to a plating treatment such as galvanization as necessary. Among these, the present invention is particularly suitably used for iron parts subjected to zinc plating or zinc alloy plating. The present invention can be used regardless of the shape of the object, and is not intended to be limited. For example, in addition to fastening parts such as bolts, washers, and nuts, flat plate pressed parts, parts to each other Naturally, it can also be used for brazed parts, straight pipe parts processed into a cylindrical shape, or parts formed with a straight pipe.

ここで、Ｐ：ネジのピッチ、ｄｅ：ネジの有効径、ｄＮ：座面等価直径、ｃｏｓα：リード角。 Examples carried out to confirm the effects of the present invention will be described. First, after performing appropriate pretreatments such as degreasing and acid soaking of the test piece, galvanization (Hyper Zincate; Nihon Surface Chemical Co., Ltd.), zinc iron alloy plating (Strong Zinc; Nihon Surface Chemistry Co., Ltd.), One of zinc-nickel alloy plating (Stron Ni zinc; Nippon Surface Chemical Co., Ltd.) was applied, and then nitric acid immersion was performed as necessary.
Next, a chemical conversion film treatment is performed by immersing the test piece in an aqueous solution having the composition described in Table 1 and Table 3 under the processing conditions described in the table, and then the test piece is taken out from the treatment liquid and washed with water by immersion. did. Then, the test piece is dipped in the aqueous solution having the composition described in the table (finishing agent of the present invention) under the processing conditions described in the table, and then the bolts are dried by centrifugal drying, and the iron plate is dried by blow drying. Went. For the test piece, iron M10 bolts, washers, nuts, and iron plates (50 mm × 100 mm, thickness 1 mm) were used. The plating film thickness was 8 to 10 μm in any plating. Bolts, washers, and nuts were used as test pieces for measuring the friction coefficient at the time of fastening. This friction coefficient (μ) is calculated by measuring torque (T) and axial force (Q) generated when fastening bolts, washers and nuts, and applying them to Equation 1.

Here, P: screw pitch, de: effective screw diameter, dN: bearing surface equivalent diameter, cos α: lead angle.

An iron plate was used as a test piece in a test in which parts hit each other and were damaged. In this test method, six steel plates are arranged in a row in a vertical and horizontal symmetry on the bottom of a plastic container (W200mm × D300mm × H100mm) and fixed with double-sided tape. The container was shaken at a frequency of 1 Hz for 1 minute with a moving width of 10 cm, and the damaged state was confirmed. The evaluation method evaluated the light condition of the surface of a test piece in three steps.
○: Same state as before test △: Part of the chemical conversion film is scratched and slightly shines in silver ×: The chemical conversion film is clearly peeled off and unevenness can be confirmed Further, the part is clearly clarified After performing a test where the two hit each other and scratch each other, a 168 hour salt spray test (JIS Z 2371) was performed to evaluate the corrosion resistance in order to confirm the degree of damage to the chemical conversion film.

  In Examples 1 to 18, the chemical conversion film treatment is performed on zinc plating, zinc iron alloy plating, and zinc nickel alloy plating, and then finish treatment is performed. In Comparative Examples 1 to 18, only the chemical conversion film treatment was performed. It turned out that a friction coefficient falls by finishing from Examples 1-10. Moreover, Examples 6-8 processed by changing the density | concentration of the same kind of finishing agent, and it turned out that it can adjust to an appropriate value easily by changing the density | concentration of polyolefin of a finishing agent. From Examples 11 to 18, it was confirmed that the appearance was hardly damaged and the results of the salt spray test were also good.

Claims (13)

Containing polyolefin, the sum concentration of Ri 0.001 to 50 g / L der, wherein the polyolefin is polyethylene, polypropylene, low density polyolefin having a density of 800~1000kg / m ^3, a thermoplastic elastomer, and co with vinyl acetate A finishing agent for a chemical conversion film, comprising at least one selected from the group consisting of polymerized resins and used for finishing treatment of fastening parts .   The finishing agent according to claim 1, wherein the polyolefin is a polyolefin having a property of aggregating on the acidic side.   The finishing agent according to claim 1 or 2, wherein the polyolefin is finely divided.   The finishing agent according to claim 3, wherein an average particle size of the finely divided polyolefin is 0.001 to 20 µm. The finishing agent according to any one of claims 1 to 4, wherein the finishing agent has a pH of 6 to 11. As the polyolefin, wherein the claim 1 having a weight average molecular weight which contain at least one polyolefin low molecular weight polyethylene of 500 to 10000, and the weight average molecular weight is selected from low molecular weight polypropylene emissions by Li Cheng group 500-10000 Item 6. The finish according to any one of Items 5 . The finish according to any one of claims 1 to 6, wherein the chemical conversion film is formed from a treatment liquid not containing hexavalent chromium having a pH of 0.1 to 6.5. The conversion coating, finish the conversion coating as claimed in any one claims 1 to 7, characterized in that it applied to the iron parts of the surface which has been subjected to zinc or zinc alloy plating. The finishing method of the said chemical conversion film using the finishing agent as described in any one of Claims 1-8 . The method according to claim 9 , wherein a part having the chemical conversion film is immersed in a finishing agent. The method of performing the finishing treatment according to claim 10 , wherein the chemical conversion film is not dried after the chemical film formation and water washing. Fastening part processed by the method according to any one of claims 9 to 11 . Treated zinc or iron component which has been subjected to zinc alloy plating by the method described in any one of claims 11 claim 9.