JP3436783B2 - Mold release agent - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mold release agent. More specifically, the present invention relates to a mold release agent suitably used in vulcanization molding of acrylic rubber. [0002] In vulcanization molding of rubber, an external coating type release agent is generally used. As such externally applied release agents, those containing silicone oil are widely used because of their good release properties. By the way, when an external mold release agent is applied to the mold surface, it is preferable to use water to eliminate the dangers of the dispersion medium, such as harmfulness and ignition, but the silicone oil itself is compatible with water. Because there is no
A method of forming a micellar state by simultaneously adding a surfactant and dispersing the micelle in water is employed. As the surfactant used at this time, ionic ones such as organic fatty acids and phosphoric acids are used from the viewpoints of cost and availability. [0003] By the way, the releasing action between the mold and the rubber is caused only by the silicone oil, and it is desirable that the silicone oil has a long lasting action. It seems that it does not adhere to the surface.
At this time, it was found that the acid component of the surfactant may decompose certain components in the acrylic rubber compounding compound, thereby generating a pollutant mainly composed of a metal salt. [0004] Such contaminants penetrate the silicone oil film to form a strong film on the mold surface, and the film once formed is such that it cannot be easily washed and removed under normal mold washing conditions. belongs to. In addition, if the release agent contains a reactive component such as a phosphate ester, it reacts with other components in the acrylic rubber as described above depending on the compounding, and contaminates the mold. This may hinder vulcanization molding of the acrylic rubber or cause problems such as hardening and softening of the surface of the vulcanized molded product and deterioration of rubber physical properties. Therefore, a solution to such a problem
As a strong acid or alkali in the molecule as a surfactant
Having a structure without a functional group acting as
-Tel type (for example, polyoxyethylene alkyl ether
Based, polyoxyethylene alkyl allyl ether based
Etc.) or polyhydric alcohol ester type (polyoxyethylene
Non-ionic such as rensorbitan alkyl ester
A method using a system surfactant is exemplified. But general
These nonionic surfactants are blended with acrylic rubber
Almost no reaction with the components is observed,
It may remain on the mold surface as a solid. This kind of solid
Shapes are formed when using other ionic surfactants
Unlike conventional contaminants, they can be easily removed under normal mold cleaning conditions.
Can be removed, but less frequent cleaning
Is important in the process, so do not produce such solids.
Is desired. SUMMARY OF THE INVENTION An object of the present invention is to provide a mold release agent containing a silicone oil, a surfactant and an aqueous dispersion medium, which is used for vulcanization molding of acrylic rubber. Even in the case, it is used during vulcanization molding of acrylic rubber, leaving almost no residue such as contaminants on the mold surface .
It is to provide a mold for release agent. SUMMARY OF THE INVENTION The object of the present invention is as follows.
Silicone oil, having the general formula RO (C2H4O) nH (where R is an alkyl group having 8 to 12 carbon atoms, and n is 3 to 1
2), a general formula (ROCH2) 2CHO (C2H4O) nH (where R is an alkyl group having 6 to 12 carbon atoms, and n is 3 to 12).
) Or the general formula (ROCH2) 3CCH2O (C2H4O) nH (where R is an alkyl group having 4 to 12 carbon atoms, and n is 3 to 20).
And is almost completely decomposed at the mold temperature during molding.
This is achieved by a mold release agent containing an ether type nonionic surfactant which volatilizes or an aqueous dispersion medium. [0007] As the silicone oil exhibiting a mold releasing action, any silicone oil that forms a film on the surface of a mold by application, thereby preventing direct contact between the mold and rubber, improving peelability, etc. Any one can be used,
For example, various silicone oils such as a simple polydimethylsiloxane type, a type having a polyether skeleton in the main chain or a type having an alkyl side chain for imparting flexibility can be used. As the aqueous dispersion medium, water is generally used, but water is added for the purpose of raising the boiling point of the liquid, preventing the liquid from scattering on the mold due to bumping, and adjusting the viscosity of the liquid. It is also used as an aqueous solution to which alcohols such as butanol and glycols such as propylene glycol and polyethylene glycol are added. Nonionic surfactants include functional groups which act as strong acidic or alkaline compounds in the molecule.
(E.g., groups such as -COOH, -POH, -NH, etc.)
Molding with a structure that easily forms micelles with silicone oil in aqueous dispersion medium and gives good dispersion state
Non-ion that decomposes or volatilizes almost completely at the mold temperature at the time
Non-ionic surfactants such as the following ether type
A surfactant is used. Compound represented by the general formula RO (C2H4O) nH R: alkyl group having 8 to 12 carbon atoms n: 3 to 12 (example) triethylene glycol-n-octyl ether triethylene glycol-n-decyl ether tetraethylene glycol-n -Decyl ether general formula (ROCH2) 2CHO (C2H4O) nHR : alkyl group having 6 to 12 carbons n: 3 to 12 general formula (ROCH2) 3CCH2O (C2H4O) nHR : alkyl group having 4 to 12 carbons n: 3 to 20 The above components are not particularly limited,
In general, both the silicone oil and the nonionic surfactant are used in an amount of about 0.001 to 0.5% by weight, with the balance being an aqueous dispersion medium to form a release agent dispersion. In addition, for convenience in storage and transportation, a concentrated solution in which both the silicone oil and the nonionic surfactant occupy about 0.1 to 50% by weight is prepared in advance, and used by diluting with an aqueous dispersion medium immediately before application. It is also possible. The release agent is applied to the mold surface by brush coating,
It can be carried out by any commonly used method such as spraying and dipping, and vulcanization molding of acrylic rubber is performed using a mold coated with such a release agent. According to the present invention, when a specific nonionic surfactant is used as a surfactant in a mold release agent containing a silicone oil, a surfactant and an aqueous dispersion medium, a compounding agent for an acrylic rubber can be obtained. And the reactivity with
During the vulcanization molding of rubber, a mold release agent that hardly leaves residues such as contaminants on the mold surface is formed. Such a mold contamination preventing effect is remarkable when a nonionic surfactant which is almost completely decomposed or volatilized at the mold temperature during molding is used. Next, the present invention will be described by way of examples. Example 1 Polyether silicone oil (L-7001) 16% by weight of triethylene glycol A nonionic release agent dispersion comprising 4% by weight of n-octyl ether, 60% by weight of propylene glycol and 20% by weight of water was prepared. Example 2 In Example 1 , tetraethylene glycol-n-octyl ether was used instead of triethylene glycol-n-octyl ether.
Decyl ether was used in the same proportions. Example 3 In Example 1 , (C) was used as a nonionic surfactant in place of triethylene glycol-n-octyl ether.
6H13OCH2) 2CHO (C2H4O) nH (n: average 5.8) was used in the same ratio. Example 4 In Example 1 , a polyoxyethylene lauryl ether-based nonionic surfactant (Kao product Emulgen 108) was used in place of triethylene glycol-n-octyl ether.
Was used in the same proportion. Comparative Example 1 In Example 1 , dilauryl phosphate, which is a phosphoric acid surfactant, was used in the same ratio instead of triethylene glycol-n-octyl ether. About 20 mg of each of the surfactants used in Examples 1 to 4 and Comparative Example 1 was taken and a thermogravimetric analyzer was used.
When the amount of the residue after heating at 200 ° C. for 2 hours was measured by Max Science Co., Ltd., the results shown in the following Table 1 were obtained. Example 4 is a nonionic surfactant that does not almost completely decompose or volatilize at a heating temperature of 200 ° C. The release agent dispersions prepared in Examples 1 to 4 and Comparative Example 1 are used as a crosslinking agent.
Mixed with Kseller PZ (Ouchi Emerging Chemicals) in a 1: 1 weight ratio
And applied on a mold. Noxeller PZ used here
Is a sulfur-containing compound that reacts with acids and bases.
Decomposes and forms a strong film mainly composed of metal salts on the mold.
It has the property of forming. Gold coated with the mixture
The mold was heated at 220 ° C., 1 kgf / cm2 for 24 hours.
After that, wash with ultrasonic cleaning with tetrahydrofuran for 10 minutes
Measure the amount of unpurified contaminants and change in weight before and after the test
It was measured by the following method. The results obtained are shown in Table 2 below.
Is shown. Further, a continuous molding experiment of an acrylic rubber composition comprising the following components was carried out using a 100-fold water dilution of the release agent dispersion prepared in Example 1. (Acrylic rubber) Epoxy group-containing acrylic elastomer 100 parts by weight (Nippon Mektron product Knoxtite PA312) FEF carbon black 40 Stearic acid 1 Cross-linking agent (Noxeller PZ) 3 It was applied to the mold surface by an air gun. When the amount of contaminants (μg) per mold at that time was measured, the results shown in the following Table 3 were obtained. Comparative Example 2 Polyether-based silicone oil (Nippon Unicar L-7001) 5% by weight polyoxyethylene sorbitan alkyl ester-based 4% by weight nonionic surfactant (Toho Chemical Sorbon T-20; HLB = 16.7) polydiethylene oxide A nonionic release agent dispersion composed of 11% by weight of propylene glycol, 60% by weight, and 20% by weight of water was prepared. Comparative Example 3 In Comparative Example 2, the polyoxyethylene sorbitan
As a kill ester nonionic surfactant, Toho Chemical
Sorbon T-85 (HLB = 11.0) was used in the same ratio. Comparative Example 4 In Comparative Example 2, polyoxyethylene sorbitan al
Instead of a kill ester nonionic surfactant, polio
Xyethylene alkyl ether nonionic surfactant
(Kao product Emulgen 120P; HLB = 16.9) used at the same ratio
Was done. In the same manner as described above, the comparative examples 2 to 4 were adjusted.
Of a 1: 1 mixture of the release agent dispersion and Noxeller PZ
Contaminants that cannot be cleaned by applying and heating the mold
When the amount was measured, the result as shown in the following Table 4 was obtained.
Was. Further, similarly to the above, the release agent prepared in Comparative Examples 2 to 4
500 times of acrylic rubber composition with 100 times water dilution of dispersion
Table 5 shows the results of a continuous molding experiment.
Results were obtained.

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁷ , DB name) B29C 33/60 B29C 35/02

Claims (1)

(57) [Claims] [Claim 1] A silicone oil having a general formula of RO (C2H4O) nH (where R is an alkyl group having 8 to 12 carbon atoms, and n is 3 to 1 )
2), a general formula (ROCH2) 2CHO (C2H4O) nH (where R is an alkyl group having 6 to 12 carbon atoms, and n is 3 to 12).
) Or the general formula (ROCH2) 3CCH2O (C2H4O) nH (where R is an alkyl group having 4 to 12 carbon atoms, and n is 3 to 20).
And is almost completely decomposed at the mold temperature during molding.
A mold release agent for use in vulcanization molding of acrylic rubber, comprising a volatile non-ionic surfactant of an ether type and an aqueous dispersion medium.