Release agent for vulcanized rubber molding

Abstract

To provide a mold release agent for vulcanized rubber molding that offers excellent release properties and cleanability. [Solution] The mold release agent for vulcanized rubber molding according to this embodiment is a mold release agent for vulcanized rubber molding that contains an alkylene oxide adduct of an amine compound having 4 to 8 active hydrogen atoms in its molecule, wherein the alkylene oxide is propylene oxide and ethylene oxide, and the number of moles of propylene oxide added per mole of amine compound is 10 moles or more and 55 moles or less, and the number of moles of ethylene oxide added is 10 moles or more and 200 moles or less.

Description

Technical Field

[0007] ,

[0001] The present invention relates to a mold release agent for vulcanized rubber molding.

Background Art

[0002] Vulcanized rubber is used in automotive parts, railway parts, construction machinery, etc. These vulcanized rubbers are obtained by injecting unvulcanized rubber into a mold, vulcanizing and molding it, and then detaching it. At that time, in order to easily detach the vulcanized rubber from the mold, a mold release agent is applied to the mold and the unvulcanized rubber.

[0003] As such a mold release agent, silicone is used, but in order to remove the mold release agent attached to the rubber hose after vulcanization, it is necessary to use a detergent or the like, and improvement in detergency is required. Therefore, a mold release agent that can be removed with water has been proposed. For example, Patent Document 1 discloses an alkylene oxide adduct of diamine.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, in order to obtain sufficient mold release properties, the mold release agent described in Patent Document 1 needs to be used in a large amount, for example, by increasing the use concentration. However, generally, when the amount used is increased, the detergency deteriorates.

[0006] An object of the present invention is to provide a mold release agent having excellent mold release properties and detergency.

Means for Solving the Problems

[0007] The present invention includes, for example, the embodiments shown below.

[0008] A mold release agent for vulcanized rubber molding according to an embodiment of the present invention is a mold release agent for vulcanized rubber molding that contains an alkylene oxide adduct of an amine compound having 4 to 8 active hydrogen atoms in its molecule, wherein the alkylene oxide is propylene oxide and ethylene oxide, and the number of moles of propylene oxide added per mole of amine compound is 10 moles or more and 55 moles or less, and the number of moles of ethylene oxide added is 10 moles or more and 200 moles or less. [Effects of the Invention]

[0009] The above-mentioned mold release agent for vulcanized rubber molding can improve wettability by reducing the contact angle with the rubber, and also has excellent mold release properties and cleanability. [Modes for carrying out the invention]

[0010] Preferred embodiments of the present invention will be described below.

[0011] The mold release agent for vulcanized rubber molding according to this embodiment contains an alkylene oxide adduct of an amine compound having 4 to 8 active hydrogen atoms in its molecule. Such an alkylene oxide adduct of an amine compound has a structure in which 4 to 8 polyoxyalkylene chains corresponding to the number of active hydrogen atoms are bonded to a residue of the amine compound. Here, the residue of the amine compound refers to the group obtained by removing the hydrogen atom from the active hydrogen group (such as an amino group) to which the alkylene oxide has been added from the amine compound.

[0012] The above amine compounds are compounds having a primary amino group (-NH2) and / or a secondary amino group (-NH-), and in this embodiment, various amine compounds having 4 to 8 active hydrogen atoms in the molecule can be used. Examples of amine compounds include aliphatic polyamines such as ethylenediamine, propylenediamine, trimethylenediamine, tetramethylenediamine, pentamethylenediamine, hexamethylenediamine, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, pentaethylenehexamine, spermine, and spermidine, as well as aromatic polyamines such as tolylenediamine, diaminoxylene, phenylenediamine, naphthalenediamine, benzidine, 2,4'-diaminobiphenyl, and 4,4'-diaminodiphenylmethane. Furthermore, the amine compounds may have hydroxyl groups in addition to amino groups, and the total number of active hydrogen atoms should be 4 to 8. Examples of compounds having an amino group and a hydroxyl group include 2-(2-aminoethylamino)ethanol, N-(3-hydroxypropyl)ethylenediamine, N-(β-aminoethyl)isopropanolamine, 1-aminopropanediol, 2-amino-2-methyl-1,3-propanediol, 2-amino-2-ethyl-1,3-propanediol, 1,1-diaminoethanol, 1,3-diaminopropanol, diaminophenol, and diaminobenzyl alcohol. These amine compounds may be used individually or in combination of two or more.

[0013] The amine compound is preferably a polyamine, and more preferably an aliphatic polyamine. In one embodiment, the amine compound may be an aliphatic polyamine having 2 to 10 carbon atoms and having 2 primary amino groups and 0 to 4 secondary amino groups, or an aliphatic polyamine having 2 to 6 carbon atoms and having 2 primary amino groups and a total of 4 active hydrogen atoms.

[0014] The alkylene oxides to be added to the above amine compound are propylene oxide and ethylene oxide, but other alkylene oxides may be used in combination as long as they do not interfere with the effects of the present invention. The addition of propylene oxide and ethylene oxide may be by block addition, random addition, or a combination thereof, and in the case of block addition, the order of addition of propylene oxide and ethylene oxide does not matter.

[0015] The number of moles of propylene oxide added per mole of the above amine compound is 10 moles or more and 55 moles or less, but preferably 20 moles or more and 40 moles or less. The number of moles of ethylene oxide added is 10 moles or more and 200 moles or less, but preferably 20 moles or more and 150 moles or less, and more preferably 50 moles or more and 100 moles or less. Here, the average number of moles added can be determined by 1H-NMR (solvent: CDCl3).

[0016] The method for adding the alkylene oxide is not particularly limited, and known methods can be used, such as introducing the alkylene oxide into a reaction vessel at 70-120°C and 0-0.3 MPa in the presence of the amine compound and catalyst, and reacting it with the amine compound. The catalyst is not particularly limited, but examples include alkali metals such as potassium hydroxide and sodium hydroxide, and alkaline earth metals such as calcium hydroxide and magnesium hydroxide.

[0017] The mold release agent for vulcanized rubber molding according to this embodiment may consist only of the alkylene oxide adduct of the amine compound, but may also be diluted with a solvent such as water. Preferably, it is diluted with water, and from the viewpoint of washability and mold release properties, the concentration of the alkylene oxide adduct of the amine compound is preferably 5 to 70% by mass, and more preferably 20 to 50% by mass.

[0018] The mold release agent for vulcanized rubber molding according to this embodiment may contain other components such as nonionic surfactants, anionic surfactants, and silicones, to the extent that they do not impair its effect.

[0019] The mold release agent for vulcanized rubber molding according to this embodiment can be used as a mold release agent when molding various vulcanized rubbers. For example, it can be used for the vulcanization molding of known rubbers such as acrylonitrile-butadiene copolymer rubber (NBR), ethylene-propylene-diene copolymer rubber (EPDM), rubber blended with NBR and polyvinyl chloride (PVC) (NBR / PVC), acrylic rubber (ACM), fluorine rubber (FKM), etc.

[0020] The vulcanization molding of rubber can be carried out according to a conventional method. For example, by applying the mold release agent of this embodiment to the mold and / or to the unvulcanized rubber, after applying the mold release agent to the part where the unvulcanized rubber contacts the mold, the unvulcanized rubber is mounted on the mold and heated and vulcanized. After vulcanization, the vulcanized rubber is taken out from the mold, and the mold release agent adhering to the rubber surface is washed with water or warm water, etc., whereby vulcanized rubber can be obtained. Note that as the unvulcanized rubber, together with the above rubbers, for example, a rubber composition blended with known additives such as vulcanizing agents, vulcanization aids, processing aids, plasticizers, process oils, carbon black, white fillers, antioxidants, etc. can be used.

Examples

[0021] Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited thereto.

[0022] The method for measuring the number average molecular weight is as follows.

[0023] (Number average molecular weight) Measured by the GPC method. The GPC apparatus and analysis conditions are as follows, and polyethylene glycols with molecular weights of 327, 2000, 8250, and 19700 were used as calibration standards. ·GPC apparatus: System controller: SCL-10A (manufactured by Shimadzu Corporation) ·Detector: RID-10A (manufactured by Shimadzu Corporation) · Column: Shodex GPC KF-G, KF-803, KF802.5, KF-802, KF-801 connected together (all manufactured by Showa Denko K.K.) · Eluent: Tetrahydrofuran · Sample injection: 0.5 wt% solution, 80 μL · Flow rate: 0.8 mL / min · Temperature: 25 °C

[0024] The raw materials used in the examples are as follows.

[0025] (Production Example 1) A stainless steel autoclave was charged with 60 g (1 mol) of ethylenediamine and 3 g of potassium hydroxide, and the inside of the reactor was purged with nitrogen. The temperature was raised to 100 °C, and a mixture of 5544 g (126 mol) of ethylene oxide and 1392 g (24 mol) of propylene oxide was introduced while maintaining the internal pressure below 0.3 MPa. After the introduction was completed, the reaction was further carried out at 100 °C for 2 hours to obtain a random adduct (A-1) of propylene oxide (24 mol) / ethylene oxide (126 mol) to ethylenediamine.

[0026] Details of the obtained alkylene oxide adduct (A-1) are shown in Table 1 below. In the table, PO (g) and PO (mol) in the type and amount of alkylene oxide used indicate the amount of propylene oxide used, EO (g) and EO (mol) indicate the amount of ethylene oxide used, and both are the amounts used per 1 mol of the amine compound (ethylenediamine in A-1). Mn indicates the number average molecular weight of the obtained alkylene oxide adduct. The same applies to (A-2) to (A-12) below.

[0027] (Production Examples 2, 3, 5 to 9) The same operations as in Production Example 1 were carried out except that the amounts of ethylene oxide and propylene oxide used were as shown in Table 1, to obtain random adducts (A-2), (A-3), (A-⑤) to (A-9) of propylene oxide / ethylene oxide to ethylenediamine.

[0028] (Production Example 4) 60 g (1 mole) of ethylenediamine and 3 g of potassium hydroxide were charged into a stainless steel autoclave, and the reactor was purged with nitrogen. The temperature was raised to 100°C, and 1392 g (24 moles) of propylene oxide was introduced while maintaining an internal pressure of 0.3 MPa or less. After the introduction was complete, the reaction was continued at 100°C for 2 hours. Subsequently, 2728 g (62 moles) of ethylene oxide was introduced while maintaining an internal pressure of 0.3 MPa or less. After the introduction of ethylene oxide was complete, the reaction was continued at 100°C for 2 hours to obtain the ethylenediamine propylene oxide (24 moles)-ethylene oxide (62 moles) block adduct (A-4).

[0029] (Manufacturing examples 10, 11) Except for using the amounts of ethylene oxide and propylene oxide listed in Table 1, the same procedure as in Production Example 4 was followed to obtain ethylenediamine propylene oxide-ethylene oxide block adducts (A-10) and (A-11).

[0030] (Manufacturing Example 12) Except for using 103 g (1 mole) of diethylenetriamine instead of ethylenediamine, and using the amounts of ethylene oxide and propylene oxide listed in Table 1, the same procedure as in Production Example 1 was carried out to obtain a random adduct of diethylenetriamine with propylene oxide (31 moles) / ethylene oxide (149 moles) (A-12).

[0031] (B-1) Dimethylpolysiloxane (product name: KF-96-20CS, manufactured by Shin-Etsu Chemical Co., Ltd.).

[0032] [Table 1]

[0033] (Examples 1-14) A mold release agent was obtained by mixing each raw material in the proportions (mass ratio) listed in Table 2 below. The following evaluations were performed using this mold release agent.

[0034] (Mold releasability) Unvulcanized rubber (ethylene-propylene-diene rubber (EPDM) or acrylonitrile-butadiene copolymer rubber (NBR)) coated with a release agent was placed in a mold (120 mm x 120 mm x 2 mm). Subsequently, vulcanization was performed at 150°C for 1 hour, and the vulcanized rubber was removed from the mold. The workability at this stage was defined as the release property, and Comparative Example 1 was used as a control to evaluate it according to the following criteria. The results are shown in Table 2. A: The workability is comparable to that when dimethylpolysiloxane is used, and the vulcanized rubber can be removed from the mold. B: Although the workability is slightly inferior to when using dimethylpolysiloxane, the vulcanized rubber can be removed from the mold. C: Workability is worse than when dimethylpolysiloxane is used, and it is difficult to remove the vulcanized rubber from the mold.

[0035] (cleanability) The vulcanized rubber obtained from the mold release evaluation was immersed in 2 L of water (temperature: 40°C) for 30 seconds, removed, and the sliminess of the vulcanized rubber surface was checked. If sliminess was present, it was immersed in a fresh 2 L of water (temperature: 40°C) for 30 seconds, and this operation was repeated until the sliminess disappeared or up to a total of three times. The cleanability was evaluated according to the following criteria. The results are shown in Table 2. Note that if sliminess is present on the vulcanized rubber surface, mold release agent remains, and if there is no sliminess, mold release agent does not remain. A: There is no slime on the surface of the vulcanized rubber after the first dipping. B: After the second dipping, there is no slime on the surface of the vulcanized rubber. C: After the third immersion, there is no slime on the surface of the vulcanized rubber. D: Even after the third dipping, the surface of the vulcanized rubber is still slimy.

[0036] [Table 2]

[0037] From each table, it can be seen that the mold release agent for vulcanized rubber molding of the present invention, i.e., the mold release agents for vulcanized rubber molding shown in each example, have excellent mold release properties and cleanability. [Industrial applicability]

[0038] The mold release agent for vulcanized rubber molding of the present invention can be used as a mold release agent to facilitate the removal of vulcanized rubber from a mold.

Claims

[Claim 1] A mold release agent for vulcanized rubber molding containing an alkylene oxide adduct of an amine compound having 4 to 8 active hydrogen atoms in its molecule, The alkylene oxides are propylene oxide and ethylene oxide. The number of moles of propylene oxide added per mole of amine compound is between 10 moles and 55 moles, and the number of moles of ethylene oxide added is between 10 moles and 200 moles. Release agent for vulcanized rubber molding.

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