JPH0976249A - Mold releasable aqueous dispersing liquid - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an aqueous dispersing liquid of silicone oil for forming a mold release film on a mold surface by thermally curing and having an excellent mold releasability. SOLUTION: The mold releasable aqueous dispersing liquid comprises methyl hydrogen silicone oil and organic tin compound. When a nonionic surfactant is further contained in the liquid, the mold releasing performance can remarkably be improved.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a releasable aqueous dispersion. More specifically, it relates to a silicone oil-based aqueous dispersion that forms a release film on the surface of a mold by heating and curing.

[0002]

2. Description of the Related Art When molding rubber, plastic, or the like with a mold, it is a common practice to apply a mold release agent to the mold surface for molding materials having poor releasability. There are two types of release agents: non-curing type and curing type.In the case of using non-curing type, depending on the shape of the mold, the release agent that is flushed to the molded product is inside the mold. Stay in certain parts,
It can affect the product.

In order to avoid such a situation, a curing type releasing agent is generally used. However, since the cured film that performs the releasing action is gradually scraped off by the molding material at the time of molding, the releasing agent is released. Curing has only about 10 to 20 times of molding, and the molding line is stopped each time, and the mold releasing agent is applied and used.

[0004] Curable release agents are often prepared using an organic solvent, and are used by spraying them onto a mold. In that case, however, deterioration of the working environment can be avoided. Absent.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to provide a silicone oil-based aqueous dispersion which forms a release film on the surface of a mold by being heat-cured and has excellent releasability. To provide.

[0006]

SUMMARY OF THE INVENTION The object of the present invention is as follows.
This can be achieved by a releasable aqueous dispersion containing methylhydrogen silicone oil and SiH group hydrolysis catalyst, but if a nonionic surfactant is further contained in the aqueous dispersion, the releasability is dramatically improved. Can be improved.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION Methylhydrogen silicone oil, which is a side chain SiH type silicone oil, has the general formula (Here, generally having values of about 100 <m + n <about 5000 and 0 <n / m <0.5), and a commercially available product is actually used as it is.

The side chain SiH group of such silicone oil is
In the presence of SiH group hydrolysis catalysts such as organotin compounds, inorganic acids, organic titanium compounds, organic amine compounds, platinum compounds, and alkali metal hydroxides, they are easily hydrolyzed even at room temperature to be converted to SiOH groups. It The degree of hydrolysis is
In the state where all SiH groups are hydrolyzed, the surface energy is too high, and the frictional force between the molded product and the release film becomes high, which is not desirable, and about 1 to 10% of SiH groups, preferably about 3%.
It is preferable that about 7% is hydrolyzed. Further, the degree of hydrolysis is adjusted by selecting the type and amount of the catalyst used.

The SiOH group thus formed does not easily react in water because of its low concentration, but it is applied to the mold as an aqueous dispersion diluted with the solid concentration to about 0.01 to 0.5% by weight. , When heated to about 150-250 ℃, Si
The OH groups are subjected to a condensation reaction to form a cured film having a -Si-O-Si- bond. That is, since such heat treatment is actually carried out by a method of spraying the aqueous dispersion on a hot mold, the water is instantaneously evaporated and the reaction product (S
Since the concentrations of the iOH group-containing silicone oil) and the catalyst (dibutyltin dilaurate, etc.) rapidly increase, the condensation reaction rapidly progresses, and the heat curing is performed in a short time.

The presence of silanol groups (SiOH groups) was confirmed in the infrared absorption spectrum of the solids obtained by drying the aqueous dispersion under reduced pressure at room temperature, while the infrared absorption spectrum of the heat-cured product showed the presence of silanol groups. It has been confirmed that it has disappeared.

The aqueous dispersion is generally about 100 parts by weight of water.
It is prepared using 0.1 to 5 parts by weight, preferably about 0.5 to 1 part by weight of methylhydrogen silicone oil and about 0.001 to 0.5 parts by weight, preferably about 0.05 to 0.1 parts by weight of the organotin compound. The aqueous dispersion can be prepared by a generally used method such as stirring and shaking.

When such an aqueous dispersion is added with a nonionic surfactant in an amount not exceeding the critical micelle concentration (CMC) of the surfactant when diluted, the releasability of the surfactant is remarkably improved.

As the nonionic surfactant, a functional group (COOH, P) having strong acidity or alkalinity in the molecule is used.
Those having an HLB value of 9 or more, preferably 10 to 12, which does not have (OH, NH groups, etc.) but easily forms micelles with silicone oil in an aqueous dispersion medium and gives a good dispersion state. Specifically, ether type ones such as polyoxyethylene alkyl ether type and polyoxyethylene alkylaryl ether type are also used, but preferably sorbitan type nonionic surfactants such as polyoxyethylene sorbitan alkyl ester type nonionic surfactants. Agent
(Alkyl groups having 8 to 12, preferably 12 to 16 carbon atoms), sorbitan fatty acid ester-based nonionic surfactants and the like are generally used.

The coating of the aqueous dispersion containing such a nonionic surfactant on the mold and the curing by heating are carried out in the same manner as in the case of the aqueous dispersion containing no nonionic surfactant.

[0015]

The releasable aqueous dispersion according to the present invention is symmetrical to the conventional aqueous dispersion containing a large amount of non-curable silicone oil and surfactant, which also causes mold contamination. In addition, since a curable silicone oil is used, a release film can be effectively formed without using a surfactant, and when a nonionic surfactant is added to this, an aqueous dispersion liquid is obtained. The storage stability, wettability to the applied mold, and releasability are significantly improved. Moreover, since the release film can be formed by heating and curing in a short time, the release film has a stable and long life,
Improvements in productivity will also be made.

[0016]

Next, the present invention will be described by way of examples.

Example 1 1 g of methylhydrogen silicone oil (KF-9901, Shin-Etsu Silicone Product) and 0.01 g of dibutyltin dilaurate
Was added to 100 ml of water, and stirred for 1 hour using a homogenizer. Then, 0.5 g of nonionic surfactant (Emulgen 106, Kao product, HLB = 10.5) manufactured by Kao Corporation was added, and the mixture was further stirred for 15 minutes. Aqueous dispersion prepared in this way with water
After diluting 10 times, it was applied on the heated mold surface with an air gun and heated at 200 ° C. for 15 minutes to form a cured film. Using this cured film forming mold, a fluororubber composition
Vulcanization molding of 100 parts by weight of Daikin Industrial Product Daniel G701 mixed with 3 parts by weight of magnesium oxide, 6 parts by weight of calcium hydroxide and 20 parts by weight of MT carbon black was performed.

In these series of operations, the following items were measured or observed. Surface tension: Measured with a surface tensiometer on an aqueous dispersion after dilution with water. Dispersion: Visually observing the degree of scattering when applying a mold. Mold conformability: Measures the mold release force during the first molding. Mold release: 10 Calculate the mold release force at the time of molding as the average mold release force Storage stability: The number of days when sedimentation of silicone oil begins to be confirmed in the aqueous dispersion before water dilution

Example 2 In Example 1, no nonionic surfactant was used.

The results obtained in each of the above examples are shown in the following table. Table Item Example 1 Example 2 Surface tension (dyne / cm) 32 54 Scatterability Small Large type Compatibility (kg) 0.8 2.6 Releasability (kg) 0.6 1.2 Storage stability (days) 30 7

Claims (2)

[Claims] 1. A releasable aqueous dispersion comprising methylhydrogen silicone oil and a SiH group hydrolysis catalyst. 2. A releasable aqueous dispersion containing methylhydrogen silicone oil, a SiH group hydrolysis catalyst and a nonionic surfactant.