JP3153963B2 - Mold with two-layer plating film - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mold having two layers of plating films and having particularly excellent releasability. In this specification, “%” means “% by weight”.

[0002]

2. Description of the Related Art For molding dies such as plastics, hard chromium plating is applied to the surface of a metal mold such as steel, copper, etc. in order to improve mold releasability and wear resistance. And the formation of a coating such as nickel plating. However, in a mold having such a coating, the releasability of a molded product is insufficient,
There is a disadvantage that the molded product adheres to the surface and the defective product generation rate increases. In order to improve the releasability, a mold release agent is applied to a mold in advance and molded. However, it is very complicated to uniformly apply the release agent to the mold, and it is necessary to repeatedly apply the release agent within a short time depending on the type of the resin, the shape of the molded product, and the like.

[0003]

SUMMARY OF THE INVENTION The present inventor has conducted research in view of the above-mentioned problems of the prior art, and has found that self-lubrication, low friction, water repellency, oil repellency, non-adhesion, etc. It was conceived to improve the performance of a mold by applying a pitch fluoride having the unique property of (1) to the mold. As a result of the subsequent research, when sequentially forming a composite plating layer and a chromium plating layer in which the pitch fluoride particles are dispersed and eutectoid in the matrix metal on the mold surface, the problems of the prior art are greatly reduced or It was found that it was practically eliminated.

[0004] That is, the present invention provides the following mold: "Two layers formed by sequentially forming a composite plating layer and a chromium plating layer in which a pitch fluoride particle is codeposited on the surface of a molded article. A mold with a plated coating of "."

Hereinafter, pitch fluoride used in the present invention, a method of forming a two-layer plating film on a mold surface according to the present invention, and the like will be described in detail.

The pitch fluoride used in the present invention has a composition formula C
A compound having a composition represented by Fx (0.5 <x <1.8), in which one to three fluorine atoms are firmly bonded to each carbon atom by a covalent bond. It has a layered structure similar to fluorinated graphite, has a brown to yellowish white to white color, and has excellent self-lubricating properties, water resistance, chemical resistance, water repellency, oil repellency, non-adhesiveness, etc. It is a very stable compound in water, and can be obtained industrially by directly reacting pitch with fluorine gas at around normal temperature. The specific manufacturing method and structure thereof are described in JP-A-62-275190.
Issue.

In the present invention, the particle size of the pitch fluoride added to the plating solution for forming the composite plating layer (hereinafter, referred to as the composite plating solution) is not particularly limited.
When the thickness is larger than the entire thickness of the plating film formed of the layer, the pitch fluoride is dropped due to the friction of the plating surface. Therefore, it is desirable to use fine-particle pitch fluoride, usually about 10 μm or less, and 1 μm or less. Those having a degree or less are more preferable. The addition amount of the pitch fluoride in the composite plating solution is not particularly limited, and may be determined depending on the stirring state of the plating solution, a desired eutectoid amount described later, and the like.
1 or less, preferably about 1 to 100 g / l.
In general, in a composite plating layer composed of a metal and an eutectoid, the adhesion between the plating layer and the substrate decreases as the volume fraction of the eutectoid increases. Also in the present invention, considering the adhesion between the plating layer and the mold, the volume fraction of the eutectoid (fluoride pitch powder or a mixture of this and other powder components) in the composite plating layer is 80%. % Is the limit. In particular, when mechanical strength is required on the plated surface, the upper limit of the volume fraction of the eutectoid is preferably 5%. The lower limit amount of the eutectoid in the composite plating layer is not particularly limited, and may be appropriately set in consideration of the type of the molding resin, the shape of the molded product, the releasability of the molded product, and the like. In order to produce the effect of eutectoid pitch fluoride, the volume fraction is preferably about 1% or more.

In the present invention, the particles can be replaced by at least one kind of particles of another fluorine compound within a range not exceeding 95% of the weight of the fluorinated pitch particles. Examples of such a fluorine-based compound include tetrafluoroethylene resin, tetrafluoroethylene-6-vinylidene fluoride copolymer,
Examples thereof include trifluoroethylene chloride resin, vinyl fluoride resin, vinylidene fluoride resin, and graphite fluoride. Also,
In the present invention, particles of an inorganic compound and an organic polymer compound are blended as an auxiliary component with an upper limit of 95% of the weight of the fluorinated pitch or the fluorinated pitch and other fluorine-based compounds, and are co-deposited in the composite plating layer. be able to. Examples of such auxiliary components include boron nitride.
These auxiliary components improve the lubricity and peelability of the composite plating layer.

In the present invention, the type of the plating solution of the metal component for constituting the matrix of the composite plating layer is not particularly limited, and ordinary electroless plating solution and electrolytic plating solution capable of depositing a metal on the surface of a mold are used. Any of these may be used. For example, nickel, cobalt, copper, chromium, zinc,
Plating solutions that can form layers of cadmium, tin, iron, lead and their alloys can be mentioned. These plating solutions are known in various compositions, and any of these known plating solutions can be used in the present invention. Among these plating solutions, a plating solution capable of forming a nickel plating layer, a nickel-cobalt alloy plating layer, a nickel-phosphorus alloy plating layer, a nickel-boron alloy plating layer, and the like having excellent heat resistance and high hardness is more preferable.

[0010] In the plating solution for forming the composite plating layer of the present invention, a surfactant is used to uniformly disperse the pitch fluoride in the plating solution. As the surfactant, it is necessary to use a surfactant molecule exhibiting cationicity at the pH of the plating solution. For example, a water-soluble cationic type, a nonionic type, or a surfactant exhibiting cationicity at the pH of the plating solution is required. Any amphoteric surfactant can be used. In this case, examples of the cationic surfactant include quaternary ammonium salts, secondary and tertiary amines, and imidazolines, and examples of the nonionic surfactant include polyoxyethylene, polyethyleneimine, and ester. And amphoteric surfactants such as carboxylic acid-based and sulfone-based surfactants. In particular, it is preferable to use a fluorinated surfactant having a CF bond in the molecule. A nonionic surfactant having a CF bond in a molecule shows cationicity only in the case of an acidic plating solution. The amount of the surfactant to be added to the plating solution is generally about 1 to 100 mg, more preferably about 1 to 30 mg, per 1 g of the pitch fluoride. In the present invention, by using pitch fluoride as the substance to be dispersed, it is possible to uniformly disperse the surfactant in the plating solution even when the amount of the surfactant used is extremely small.
As a result, the amount of the surfactant attached to the fluorinated pitch decreases, and high water repellency can be exhibited even immediately after plating.

In the present invention, known additives such as a primary brightener and a secondary brightener can be further added to the above composite plating solution.

In forming a composite plating layer in the present invention, it is preferable to perform plating while stirring a plating solution in order to uniformly disperse the fluoride pitch. The stirring method is not particularly limited, and ordinary mechanical stirring means, for example, a method of screw stirring, a method of stirring with a magnetic stirrer, and the like can be adopted. The plating conditions may be appropriately determined according to the type of plating solution to be used, and generally, the same solution temperature, pH, current density, and the like as in the case of ordinary plating may be employed. The thickness of the composite plating layer according to the present invention varies depending on the type of the molding material, the type of the matrix metal, the shape of the mold, and the like, but is usually about 1 to 100 μm. Note that the composite plating layer in the present invention does not necessarily need to be directly formed on a mold, and may be formed on a mold after forming a known base plating layer (for example, copper plating) on the mold. .

In the mold of the present invention, a chromium plating layer is further provided on the composite plating layer. The type of the chromium plating solution is not particularly limited, and may be any of a normal electroless plating solution and an electrolytic plating solution capable of depositing chromium on the metal surface of the composite plating. Also, the plating conditions may be appropriately determined according to the type of plating solution to be used, and generally, the same solution temperature, pH, current density, etc. as in the case of ordinary chromium plating may be employed. The thickness of the chromium plating layer according to the present invention is not particularly limited, but is usually about 0.1 to 100 μm.

The two-layer plating film formed on the mold as described above may be subjected to surface finishing by polishing or the like, if necessary.

[0015]

In the mold having the two-layer plating film of the present invention, the chromium plating film is formed only on the matrix metal particles of the composite plating layer, and the chromium plating film is not formed on the eutectoid pitch fluoride particles. Since it has not been formed,
The pitch fluoride particles are in a state as if dispersed in the chromium plating layer, and most of the pitch fluoride particles are exposed on the surface of the two-layer plating film. Therefore, when the mold according to the present invention is used, the pitch fluoride particles give the mold excellent mold release properties. Also, when a release agent is used in combination, the release property is synergistically enhanced. Furthermore, the presence of the fluorinated pitch particles imparts good water repellency and oil repellency to the mold, and significantly reduces the adhesion of the molding object.
Further, since the chromium plating layer having high hardness present on the surface functions as a protective layer, wear of the mold is reduced and durability of the mold is improved. Furthermore, the two-layer plating film according to the present invention has excellent adhesion to a mold and excellent mechanical strength. Accordingly, the mold according to the present invention is a mold for molding resins such as polyethylene, polypropylene, polyvinyl chloride, polyvinyl acetate, ethylene-vinyl acetate copolymer, polyester, natural and synthetic rubbers, glass and ceramics. Is extremely useful.

[0016]

The present invention will be described in more detail with reference to the following examples.

Example 1 A coal tar pitch having a softening point of 100 ° C., a quinoline-insoluble matter (QI) of 0.2%, and a benzene-insoluble matter (BI) of 30% was used.
A double amount of hydrogenated anthracene oil was added, heated at 430 ° C. for 90 minutes, and then the reduced pitch was obtained by removing the hydrogenated anthracene oil at 300 ° C. under reduced pressure.

Next, nitrogen gas is introduced into the obtained reduced pitch to remove low molecular weight components, and then thermally polymerized at 400 ° C. for 5 hours to obtain a softening point of 300 ° C., a QI of 60% and a BI of 98.
%, And a mesophase pitch having a mesophase content of 90% or more was obtained.

After 50 g of the obtained pitch was charged into a nickel-made reaction vessel, the system was evacuated and then filled with argon gas. Then, at 70 ° C., a fluorine-containing gas (20
(vol.% fluorine, 80 vol.% argon mixed gas) was allowed to react for 20 hours while flowing at an average flow rate of 650 cc / min, and 144 g of pitch fluoride was obtained. Upon elemental analysis, the composition formula was CF _1.39 .

The powder of the pitch fluoride (? Μm) thus obtained was added in an amount of 1% to a nickel electrolytic plating solution having the following composition. At this time, a tertiary perfluoroammonium salt (C ₈ F ₁₇ SO ₂ NH) is used as the surfactant.
(CH ₂ ) ₃ N ⁺ (CH ₃ ) ₃ .Cl ⁻ ) was added so as to be 4.5 mg per 1 g of pitch fluoride.

Composition of nickel electroplating solution Nickel sulfate hexahydrate 280 g / l Nickel chloride hexahydrate 45 g / l Boric acid 40 g / l Primary brightener 2 g / l Secondary brightener 0.2 g / l Nickel plate and steel mold (For molding ethylene-vinyl acetate copolymer) as a positive electrode and a negative electrode, respectively.
The plating was carried out under the conditions of 5 ° C. ± 5 ° C., pH 4.2, and a cathode current density of 4 A / dm ² with an electric quantity of 1,000 coulombs while stirring the screw. Approximately 6% by volume of pitch fluoride powder was eutectoid in the obtained composite plating film.

Then, a chromium plating film having a thickness of 0.1 μm was formed on the composite plating film obtained above using a chromium plating solution having the following composition under the following conditions. Chromium plating solution composition CrO ₃ 250 g / l Cr- ⁶ 2.5 g / l H ₂ SO ₄ 2.0 g / l Chromium plating conditions Solution temperature 45 ° C. Cathode current density 15 A / dm ² Anode Lead time 3 minutes 2 layers obtained In plating, many of the fluoride pitch particles exposed on the surface of the lower composite plating film formed on the mold are slightly exposed from the surface of the upper chromium plating layer, The particles had such a form that the particles were also dispersed in the chromium plating layer.

Comparative Example 1 A nickel plating film and a chromium plating film were sequentially formed on a mold surface in the same manner as in Example 1 except that pitch fluoride was not added.

Reference Example 1 Using the molds obtained in Example 1 and Comparative Example 1, a polyurethane resin was molded. When the mold obtained in Example 1 was used, the molding operation could be smoothly performed 10 times continuously without using a release agent. On the other hand, when using the mold obtained in Comparative Example 1,
When the release agent was not used, the resin was immediately adhered and molding could not be performed.

Comparative Example 2 A two-layer plating film was formed on the surface of a mold in the same manner as in Example 1 except that polytetrafluoroethylene particles were used instead of pitch fluoride particles. The resulting mold was used to mold a polyurethane resin. If a mold release agent was not used, the resin would adhere after seven molding operations and the molding operation could not be performed thereafter. Did not.

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) B29C 33/00-33/76

Claims (1)

(57) [Claims] 1. A mold having a two-layer plating film in which a composite plating layer in which pitch fluoride particles are codeposited and a chromium plating layer are sequentially formed on a surface on which a molded article is formed.