JPH08283771A - Water-dispersible release agent composition - Google Patents

Abstract

PURPOSE: To prepare a water-dispersible compsn. which can satisfy the releasability of a vulcanized molding and the deposition of contaminants onto the surface of a molding in a well-balanced manner by dispersing a silicone oil with the aid of a particular nonionic surfactant. CONSTITUTION: This compsn. comprises a water-dispersible release agent comprising a silicone oil dispersed with the aid of a nonionic surfactant, and a sorbitan mono-higher-alkyl ester and another nonionic surfactant are used in combination as the nonionic surfactant. The sorbitan mono-higher-alkyl ester is one having an 8-20C higher alkyl group. As another nonionic surfactant, one which is substantially completely decomposed or evaporated at the mold temperature during molding, is preferable. The amounts of the sorbitan mono-higher-alkyl ester and the surfactant used are such that the amount of the former is about 0.1 to 2 times (by weight) that of the latter. The silicone oil and the nonionic surfactant are each used in an amt. of 0.001 to 0.5wt.% with the balance of the compsn. consisting of an aq. dispersion medium.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a water-dispersed release agent composition. More specifically, it relates to a water-dispersed release agent composition that is preferably used during vulcanization molding of acrylic rubber.

[0002]

2. Description of the Related Art An external coating type mold release agent is generally used during vulcanization molding of rubber. As such an external coating type release agent, one containing silicone oil is widely used because of its excellent releasability. By the way, when an external release agent is applied to the mold surface, it is preferable to use water in order to eliminate the danger of the dispersion medium, such as the toxicity and the ignitability, but the silicone oil itself is compatible with water. Because there is no
A method of adding a surfactant at the same time to form a micelle state and dispersing it in water is adopted. As the surfactant used at this time, ionic compounds such as organic fatty acid salt-based compounds and phosphate-based compounds are used because of their price and availability.

By the way, the releasing action between the mold and the rubber is brought about only by the silicone oil, and it is desirable that the component has a long-lasting effect. It seems that it will not adhere to.
At this time, it was found that the acid component of the surfactant sometimes decomposes certain components in the acrylic rubber compounding agent to generate a contaminant containing a metal salt as a main component.

Such contaminants penetrate the silicone oil film to form a strong film on the surface of the mold, and the film once formed cannot be easily removed by cleaning under normal mold cleaning conditions. belongs to. In addition to this, when the mold release agent contains a reactive component such as a phosphoric acid ester, it may react with the other components contained in the acrylic rubber as described above depending on the formulation, thereby contaminating the mold. Or hinder the vulcanization and molding of the acrylic rubber, or cause problems such as surface hardening or softening of the vulcanized molded product and deterioration of rubber physical properties.

[0005]

The present applicant has previously found that when a mold release agent containing a silicone oil, a surfactant and an aqueous dispersion medium is used during vulcanization molding of acrylic rubber. Also proposes a composition containing silicone oil, a specific nonionic surfactant, and an aqueous dispersion medium as a water-dispersed release agent composition that leaves almost no residue such as contaminants on the mold surface. (Japanese Patent Application No. 5-294,494
issue).

The proposed water-dispersed release agent composition is
Even when this is used during the vulcanization molding of acrylic rubber, it achieves the intended purpose of leaving almost no residue such as contaminants on the mold surface, but the releasability indicated by the releasability is It was not good at all, and there was a problem that the vulcanized molded product was cracked or torn during release.

The object of the present invention is to improve the releasability of a vulcanized molded article even when a water-dispersed release agent in which silicone oil is dispersed with a nonionic surfactant is used for vulcanization molding of acrylic rubber. It is an object of the present invention to provide a water-dispersed release agent composition for mold application, which can satisfy both deposition of contaminants on the surface of the mold in a well-balanced manner and, as a result, can enhance the process yield.

[0008]

SUMMARY OF THE INVENTION The object of the present invention is as follows.
In a water-dispersed release agent in which silicone oil is dispersed with a nonionic surfactant, a water-dispersed release agent composition in which a sorbitan mono-higher alkyl ester as a nonionic surfactant and another nonionic surfactant are used in combination To be achieved.

As the silicone oil exhibiting a releasing action, any silicone oil having a function of forming a film on the surface of the die by coating, thereby preventing direct contact between the die and rubber, and improving the releasability, etc. Any can be used,
For example, various silicone oils such as a simple polydimethylsiloxane-based one, a polyether skeleton in the main chain for imparting flexibility, or an alkyl side chain can be used.

Sorbitan mono higher alkyl ester The higher alkyl group R has 8 to 20 carbon atoms, preferably 12 to 16 carbon atoms.

Nonionic surfactants other than sorbitan mono higher alkyl ester include (1) ether type or polyhydric alcohol ester type, (2) those which decompose or volatilize almost completely at the mold temperature during molding, or (3 ) Polymeric acrylics are used.

Nonionic surfactants of the type (1) above do not have a functional group (eg, --COOH, --POH, --NH etc.) that acts as a strong acid or alkaline in the molecule. , An ether type (for example, polyoxyethylene alkyl ether type, polyoxyethylene alkyl allyl ether type, etc.) having a structure that easily forms micelles with silicone oil in an aqueous dispersion medium and gives a good dispersion state, or A polyhydric alcohol ester type (polyoxyethylene sorbitan alkyl ester type or the like) is used, and it may be used in combination with other components such as a stabilizer.

Although these nonionic surfactants hardly react with the compounding ingredients of the acrylic rubber, thermal decomposition residues may remain as solids on the surface of the mold.
Unlike contaminants formed when other ionic surfactants are used, this type of solid matter can be easily removed under normal mold cleaning conditions, but the cleaning frequency is reduced. Since it is important in the process, it is desirable not to produce such solid matter.

From this point of view, the nonionic surfactant of the type (2), that is, the nonionic surfactant which is almost completely decomposed or volatilized at the mold temperature during molding, for example, the following ether type nonionic It is preferable to use a surfactant. Compound represented by general formula RO (C ₂ H ₄ O) 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 tetra ethylene glycol -n- decyl ether formula _{(ROCH 2) 2 CHO (C} 2 H 4 O) nH R: alkyl group having 6 to 12 carbon atoms n: 3 to 12 formula _{(ROCH 2) 3 CCH 2 O} (C ₂ H ₄ O) nHR: C4-12 alkyl group n: 3-20

Further, as the polymer acrylic nonionic surfactant of the type (3), an alkyl acrylate and a general formula CH ₂ ═CHCO (OCnH ₂ n) mOR R: an alkyl group having 1 to 12 carbon atoms n : 2 or 3 m: an alkylated polyalkylene glycol ester of acrylic acid represented by an integer of 2 to 30, for example, triethylene glycol-n-
Octyl ether, triethylene glycol-n-decyl ether, tetraethylene glycol-copolymer with acrylic ester such as n-decyl ether, a polymer having a degree of polymerization of about 10,000 to 100,000, preferably about 30,000 to 80,000. An acrylic nonionic surfactant is used. Regarding the copolymerization ratio between the two, although the HLB value increases as the latter acrylic acid ester copolymerization ratio increases, and more silicone oil can be solubilized, the copolymerization ratio is too high. If it is too much, the copolymer will be crystallized. Therefore, the proportion thereof is preferably about 80 mol% or less, preferably about 60 to 70 mol%.

The sorbitan mono-higher alkyl ester and the other nonionic surface active agent have about 0.2% of the former one.
It is used in a weight ratio of 1 to 2 times, preferably about 0.5 to 1 times. If the proportion of the former used is less than this, the intended effect aimed at by the present invention will not be exhibited, while if it is used in a proportion greater than this, the dispersion in water will be poor.

The silicone oil is prepared into a water-dispersible release agent composition by using these nonionic surfactants. As the aqueous dispersion medium used at that time, water is generally used, but it is added for the purpose of increasing the boiling point of the liquid, preventing the liquid from scattering on the mold due to bumping, or adjusting the viscosity of the liquid. It is also used as an aqueous solution to which alcohol such as butanol and glycol such as propylene glycol and polyethylene glycol are added.

Each of the above components is not particularly limited,
Generally, silicone oil and each nonionic surfactant are used in an amount of about 0.001 to 0.5% by weight, the balance being an aqueous dispersion medium to form an aqueous dispersion of a release agent. In addition, for convenience of storage and transportation, a concentrated solution in which the silicone oil and the nonionic surfactant account for about 0.1 to 50% by weight is prepared in advance, and the concentrated solution is prepared with an aqueous dispersion medium immediately before coating.
It is also possible to use it by diluting 50 to 800 times.

The release agent composition can be applied to the surface of the mold by any commonly used method such as brush coating, spraying, dipping, etc., and such a release agent composition is applied. The acrylic rubber is vulcanized and molded using the mold.

[0020]

EFFECTS OF THE INVENTION In a water-dispersed mold release agent for mold application, which uses silicone oil as an external mold release agent, although the accumulation of contaminants on the mold is reduced, only a difficulty in mold release property is observed. By using sorbitan mono-higher alkyl ester and other nonionic surfactants together as nonionic surfactants, both the releasability of vulcanized molded products and the accumulation of contaminants on the mold surface are well balanced. As a result, the yield of the process can be improved by reducing the cracks and tears of the vulcanized molded product, and at the same time, the work capacity can be improved by reducing the amount of contaminants deposited.

Therefore, the water-dispersed release agent composition according to the present invention is effectively applied to the molding die surface as a release agent for external application during vulcanization molding of rubber, particularly acrylic rubber.

[0022]

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

Example Polyether Silicone Oil (N-7 Unicar Product L-7001) 16% by weight Polyoxyethylene sorbitan alkyl ester 2.0 〃 Nonionic surfactant (Toho Chemicals Sorbon T-20; HLB = 16.7) Sorbitan Monolaur A mold release agent composition comprising a rate (Span 20) 2.0 〃 propylene glycol 60 〃 water 20 〃 was prepared.

Comparative Example 1 In the examples, only Sorbon T-20 was changed to 4.0% by weight as the nonionic surfactant.

Comparative Example 2 In the example, the surfactant component was changed to 4.0% by weight of dilaurate phosphate alone.

The release agent compositions prepared in the above Examples and Comparative Examples were each diluted 400 times with water, and the diluted solution was applied with an air gun for each vulcanization molding. Elastomer 100 parts by weight (Nippon Mektron product Knoxtite PA312) HAF carbon black 40 〃 Stearic acid 1 〃 Crosslinking agent (Nocceller PZ) 3 〃 Acrylic rubber composition compression vulcanization molding (vulcanization condition: 180 ℃, (30 minutes), measure the mold release force per die at each molding with a push-pull gauge, and measure the amount of contaminants per die attached on the die to 500.
It was measured after molding once. The results obtained are shown in the following table. The release force is the average value of 10 measurements. Table Examples release force (kg) contaminant content ([mu] g) Example 1.3 30 Comparative Example 1 2.2 25 〃 2 1.0 190

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI technical display location C10N 30:04 40:36

Claims (2)

[Claims] 1. A water-dispersed release agent in which silicone oil is dispersed in a nonionic surfactant, wherein a sorbitan mono-higher alkyl ester and another nonionic surfactant are used in combination as the nonionic surfactant. Mold composition. 2. The water-dispersed release agent composition according to claim 1, which is used during vulcanization molding of acrylic rubber.