JPS595535B2 - Method for manufacturing glass molded bodies - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a glass molded body, and more specifically, a method for manufacturing a glass molded body by pouring molten glass into a mold coated with a high-performance lubricating mold release agent and baked. Regarding.

Here, the term "glass molded object" refers to a molded object produced by a press-blow method or a blow-blow method using a set mold and a finishing mold such as a narrow-mouth bottle or a wide-mouth bottle, and a molded object manufactured using only a press mold such as a plate. The molded bodies manufactured by

Usually, a gob of glass melted at about 1,100 to 1,200°C is put into a mold and pressed or blown to form a glass molded object, and the friction between the inner surface of the mold and the molten glass Lubrication is applied to the inner surface of the mold to prevent defects such as wrinkles on the surface of the molded object by reducing the resistance, and to make it easier to separate the molded object from the mold after molding. The agent is being applied.

The lubricating mold release agent that has been widely used in the past is one in which powdered graphite is dispersed in an oil-based liquid.
This type of lubricating mold release agent is exposed to high temperatures during molding, so it is subject to significant wear and tear due to oxidation or adhesion to glass molded objects, and one application can only be used for around 50 to 100 molding operations. Ta.

In order to overcome the drawback of poor durability of oil-based lubricating mold release agents, one of the inventors of the present invention previously published a patent application in Japanese Patent Application Laid-open No.
No. 150,422 proposed a lubricating mold release agent containing graphite and a metal acid phosphate and an acidic aqueous solution.

This type of lubricating mold release agent has excellent durability and can be molded approximately 30,000 times (number of gob shots) with one application depending on the working conditions.

However, when this is applied to a mold with an O trowel at room temperature, it reacts with the mold material (often made of cast iron) after application because it is acidic and generates hydrogen gas, causing air bubbles between the coating film and the mold surface. Generate and
There was a problem with the paint film peeling off.

Furthermore, because it is acidic, it is difficult to select a container and handle it.

In order to prevent the former problem (in this case, the mold is approximately 80 to 20
It is best to preheat to 0°C before applying the coating, but in this case, the coating must be heated twice (including reheating to bake the coating) (to dry the coating before hydrogen gas is generated). Another problem arises in that heating is required, which increases the number of steps.

The present invention aims to solve the problems of the prior art described above.

In order to achieve the above object, the present invention provides a method of manufacturing a glass molded body by molding a lump of molten glass using a mold, wherein the molten glass is to be brought into contact with the mold during the molding. The surface is coated with a lubricating mold release agent whose main ingredients are powdered graphite, an acidic metal phosphate, an aliphatic amine, and a diluent made of water and/or a solvent, forming a baked film. The present invention provides a method for manufacturing a glass molded body.

The present invention will be explained in detail below.

The lubricating mold release agent used in the present invention includes powdered graphite that has a lubricating effect, an acidic metal phosphate that acts as a binder for the powdered graphite, and an acidic metal phosphate that increases the pH of the acidic metal phosphate.
Preferably, the main ingredients are an aliphatic amine to substantially neutralize the salt, and a diluent consisting of water and/or a solvent to improve coating properties.

The binder for the lubricating mold release agent used in the present invention is one that has adhesive properties in its aqueous solution, has high heat resistance (at least at about 400 to 600°C) strength of the baked solidified film, and is difficult to react with molten glass. Acidic metal phosphates are used.

Such acidic metal phosphates include monobasic aluminum phosphate, monobasic chromium phosphate, monobasic magnesium phosphate, monobasic nickel phosphate, monobasic zirconium phosphate, etc., singly or in mixtures thereof, or in combination with phosphoric acid (orthophosphoric acid, methacrylate). Examples include those to which phosphoric acid, pyrophosphoric acid, etc.) are added.

In particular, the addition of an appropriate amount of the latter phosphoric acid contributes to an increase in heat resistance strength.

The above acidic metal phosphate solution exhibits relatively strong acidity (pH about 15 to 2.0).

Therefore, if left as is, the above-mentioned problems will occur.

Therefore, it is necessary to raise the pH to a level that does not easily react with the mold, that is, to about pH 6 or higher.

The first possible means for this are KOH, NaO
However, according to research by the present inventors, when neutralized by such a method, the viscosity of the binder is lost and the dry film strength and heat resistance are reduced. It has been found that the strength is reduced and therefore the durability of lubricating mold release agents using such binders is also reduced and the number of shots possible with a single application is significantly reduced.

However, when neutralized with an aliphatic amine, the viscosity is not lost, and therefore high dry film strength and heat resistance can be maintained, and the durability of lubricating mold release agents using such a binder is significantly improved. It has been found that the present invention has achieved this goal.

Although the reason why the viscosity is not lost as described above is not necessarily clear, it is presumed that it is related to the phenomenon in which acidic phosphates and aliphatic amines tend to form chelates.

Examples of such aliphatic amines include butylamine, dipropylamine, triethylamine, ethylenediamine, monoethanolamine, jetanolamine, triethanolamine, propatoolamine, and the like.

The amount of aliphatic amine added is such that the pH of the acidic metal phosphate is approximately 6-6.
It is desirable to increase the number to 8.

When the pH is lower than about 6, hydrogen gas is generated due to the reaction between the lubricating mold release agent coating applied at room temperature and the mold surface, making it easy for the coating to peel off from the mold surface. On the other hand, adding an excess of aliphatic amine to raise the pH to about 8 or higher is meaningless from the standpoint of preventing peeling, and conversely, it causes baking (
(usually carried out at about 250 to 300°C), a large amount remains, which may lead to a decrease in the strength of the coating film.

Ordinary powdered graphite (0.5 to 3% by weight in terms of impurity content) may be used, but if particularly refined high-purity powdered graphite with an impurity content of 0.002% by weight or less is used, It has been found that the heat resistance of the lubricating mold release agent is further improved.

That is, when using a mold coated with the lubricating mold release agent of the present invention containing ordinary powdered graphite, the inside temperature of the mold is 5.
At temperatures below 00°C, the wear of the lubricating release film is extremely small, and the number of shots possible with one application is extremely large.

However, if the inner surface temperature is increased above 500°C (effective for smoothing the surface of the molded product), the wear and tear will rapidly increase, and the number of possible shots will also sharply decrease.

However, it has been found that when the above-mentioned high-purity powdered graphite is used, even if the inner surface temperature of the entire mold reaches 600°C, the possible number of shots is close to 0 at 500°C.

Although the reason for this is not necessarily clear, it is presumed that impurities (ash) contained in powdered graphite act as a catalyst that promotes oxidative consumption of graphite.

The blending weight ratio of powdered graphite and acidic metal phosphate in the lubricating mold release agent is preferably 1/6 to 6.

If the amount of powdered graphite is less than the lower limit of 1/6 above, the lubricating mold release property will be lost, wrinkles etc. will occur on the surface of the molded product, and the molded product will not adhere to the mold surface during mold release. This is because troubles such as difficulty in mold release are likely to occur.

On the other hand, if the amount exceeds the upper limit of 6, the bond between the powdered graphite will be lost, the strength of the coating will decrease, and the durability will be impaired.

The diluent is water alone, a solvent such as ethyl alcohol,
Alternatively, it is added in the form of a mixture of water and a solvent.

Depending on the type of aliphatic amine to be blended, a solvent is selected that has solubility for the aliphatic amine.

The amount of diluent to be blended is determined depending on the method of applying the lubricating mold release agent to the mold; for example, in the case of spray coating, a relatively large amount is blended, and in the case of brush coating, a relatively small amount is blended.

The present invention (the lubricating mold release agent used herein does not preclude the addition of a small amount of other ingredients, such as boric acid as a stabilizer, or sugar or starch that contributes to improving slipperiness, in addition to the above ingredients). .

Using the above lubricating mold release agent, the glass molded product is made as follows [
It is produced by straining.

First, glass molds at room temperature (set molds, baffles, U-types, bottom molds,
The above-mentioned lubricating mold release agent is sprayed onto at least the surface of the finishing mold, press mold, etc. that is to come into contact with the molten glass during molding.
Apply as evenly as possible using an appropriate method such as brushing or dipping.

The coating amount is preferably selected so that the solid film thickness after baking and drying is within the range of 5 to 60 μm, and more preferably 20 to 5 μm.
It is more desirable to select it within the range of 0 μm.

If it is thinner than 5 μm, the coating will wear quickly, and the number of shots per coating will be significantly reduced, requiring frequent mold replacement. On the other hand, if it is thicker than 60 μm, the coating will easily peel off, and Heat transfer becomes poor and the temperature of the inner surface of the coating film rises too much, causing problems such as slow cooling of the molded product after molding, lengthening the time to release from the mold, and resulting in a decrease in productivity. It is from.

The mold coated with the lubricating mold release agent as described above is preferably heated at about 250 to 350° C. for about 1 to 2 hours, for example, in an oven to bake and solidify the coating film.

At this time, it is assumed that most of the aliphatic amine evaporates together with the diluent.

A molten glass lump of, for example, 1100 to 1200° C., a so-called gob, is put into the mold prepared as described above and molded into a glass molded body.

When the glass molded object is a bottle, etc.
In the case of molding using a blow-finishing mold or a press-blowing mold, a parison formed by a set mold (with a molten state inside and a solid thin film formed on the surface) is placed in a blow-finishing mold.

According to the present invention, a coating film of a lubricating mold release agent using an acidic metal phosphate having excellent heat resistance and durability as a binder is formed on the mold surface for molding a glass molded object. It has the effect that the number of shots possible per application is much larger than when conventional oil-based lubricating mold release agents are used.

Furthermore, by blending high-purity powdered graphite, the above-mentioned high durability can be maintained even when the mold inner surface temperature is about 500 to 600°C.

In addition, an aliphatic amine is blended in the lubricating mold release agent, but
Due to the above formulation, tackiness is not lost and, therefore, coatability is not impaired.

Even if a lubricating mold release agent is applied to a mold at room temperature, the lubricating mold release agent can be applied to a mold at room temperature to the extent that no hydrogen gas is generated during the baking process.
By controlling H by adjusting the amount of aliphatic amine blended, it is possible to prevent the coating film from peeling off, and therefore the process of preheating the mold can be omitted, and furthermore, it has the advantage of being easier to handle.

The present invention will be explained below with reference to Examples.

Example 1 35 g of powdered graphite with an average particle size of 25 μm (impurity content 1.2% by weight), 25 g of primary aluminum phosphate, 30 g of orthophosphoric acid
A lubricating mold release agent was prepared by mixing and stirring 1 g, 32 g of monoethanolamine, 50 g of water, and 250 g of ethyl alcohol.

Its pH was 7.0.

This lubricating mold release agent was sprayed onto the inner surfaces of the body side mold, bottom mold, mouth mold and baffle of a room temperature cast iron assembly mold for press-blow molding so that the solid film thickness was approximately 30 μm. Thereafter, the coating was baked and solidified by heating in an oven at 300° C. for 80 minutes, but no peeling occurred.

A gob at about 1140° C. was put into this mold and a parison was press-molded.

The internal temperature of the mold at this time was approximately 450°C and 500°C.
, 550°C and 600°C.

The number of normal parisons produced without defects such as wrinkles, ie, the number of shots, was counted.

Note that the inner surface temperature was measured using a radiation thermometer.

The results are shown in Table 1.

It can be seen that excellent durability is exhibited at temperatures below 500°C.

Example 2 A parison was produced in the same manner as in Example 1, except that high-purity powdered graphite lead with an impurity content of 0.001% by weight was blended, and the number of shots to obtain a normal parison was counted.

The results are shown in Table 1. It can be seen that excellent durability is exhibited even at temperatures higher than 500°C.

Comparative Example 1 A lubricating mold release agent was prepared using the same formulation as in Example 1, except that monoethanolamine was not added.

Its pH was 2.0. This was coated on a mold and baked under the same conditions as in the example, but after baking the coating had peeled off and could not be used.

Claims (1)

[Claims] 1. In a method of manufacturing a glass molded body by molding a lump of molten glass using a mold, the surface of the mold with which the molten glass comes into contact during the molding includes: A glass molded article characterized in that a lubricating mold release agent containing powdered graphite, an acidic metal phosphate, an aliphatic amine, and a diluent consisting of water and/or a solvent as the main ingredients is coated and a baked film is formed. Production method. 2. The method for producing a glass molded body according to claim 1, wherein the content of impurities in powdered graphite is 0.002% by weight or less. 3. The glass forming according to claim 1, wherein the acidic metal phosphate is composed of monobasic aluminum phosphate, monobasic chromium phosphate, monobasic magnesium phosphate, monobasic nickel phosphate, or monobasic zirconium phosphate, and phosphoric acid. How the body is manufactured. 4. The lubricating mold release agent contains the aliphatic amine in an amount sufficient to substantially neutralize the acidic metal phosphate and bring the pH of the lubricating mold release agent to about 6 to 8. 2. A method for producing a glass molded article according to item 1. 5. The method for producing a glass molded body according to claim 1, wherein the blending weight ratio of the powdered graphite and the acidic metal phosphate in the lubricating mold release agent is within the range of 1/6 to 6. 6 Application of lubricating mold release agent, thickness of baked film is 5 to 60 μm
A method for manufacturing a glass molded body according to claim 1. 7. The method for producing a glass molded body according to claim 1, wherein the baking temperature of the lubricating mold release agent is 250 to 350°C.