JP6937225B2 - Release agent for vulcanized rubber molding - Google Patents

Description

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

Vulcanized rubber is used in automobile parts, railway parts, construction machinery, and the like. These vulcanized rubbers can be obtained by putting unvulcanized rubber into a mold or the like, vulcanizing and molding the rubber, and then desorbing the unvulcanized rubber. At that time, a mold release agent is applied to the mold and the unvulcanized rubber in order to easily attach and detach the vulcanized rubber from the mold.

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

Japanese Unexamined Patent Publication No. 7-292236

An object of the present invention is to provide a mold release agent having excellent mold releasability and detergency.

The mold release agent for vulture rubber molding according to the embodiment of the present invention is an amine compound alkylene oxide adduct (A) obtained by adding an alkylene oxide to an amine compound having 4 to 8 active hydrogen atoms in the molecule. , And the surfactant (B).

The above-mentioned mold release agent for vulcanized rubber molding can reduce the contact angle with rubber to improve wettability, and is excellent in mold release and detergency.

The release agent for molding vulcanized rubber according to the present embodiment contains an alkylene oxide adduct (A) of an amine compound having 4 to 8 active hydrogen atoms in the molecule. The alkylene oxide adduct (A) of such an amine compound has a structure in which 4 to 8 polyoxyalkylene chains corresponding to the number of active hydrogen atoms are bonded to the residue of the amine compound. Here, the residue of the amine compound refers to a group obtained by removing the hydrogen atom of an active hydrogen group (amino group or the like) to which an alkylene oxide is added from the amine compound.

The amine compound is a compound having a primary amino group (-NH ₂ ) and / or a secondary amino group (-NH-), and in the present embodiment, various types having 4 to 8 active hydrogen atoms in the molecule. Amine compounds can be used. Examples of the amine compound include aliphatic groups such as ethylenediamine, propylenediamine, trimethylenediamine, tetramethylenediamine, pentamethylenediamine, hexamethylenediamine, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, pentaethylenehexamine, spermin and spermidin. Examples include aromatic polyamines such as polyamines, tolylenediamines, diaminoxylenes, phenylenediamines, naphthalenediamines, benzidines, 2,4'-diaminobiphenyls and 4,4'-diaminodiphenylmethanes. Further, the amine compound may have a hydroxyl group together with an amino group, and the total number of active hydrogen atoms may be 4 to 8. Examples of the compound having an amino group and a hydroxyl group include 2- (2-aminoethylamino) ethanol, N- (3-hydroxypropyl) ethylenediamine, N- (β-aminoethyl) isopropanolamine, and 1-aminopropanediol. 2-Amino-2-methyl-1,3-propanediol, 2-amino-2-ethyl-1,3-propanediol, 1,1-diaminoethanol, 1,3-diaminopropanol, diaminophenol, diaminobenzyl alcohol And so on. Each of these amine compounds may be used alone or in combination of two or more.

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

The alkylene oxide added to the amine compound may be ethylene oxide alone, but it is preferable to use ethylene oxide in combination with other alkylene oxides. As one embodiment, ethylene oxide and propylene oxide and / or butylene oxide may be used, and more specifically, ethylene oxide and propylene oxide are preferably used in combination because they are excellent in detergency.

When two or more kinds of alkylene oxides are added, the addition form may be block addition, random addition, or a combination thereof. That is, the polyoxyalkylene chain may be a block adduct of an oxyethylene group and another oxyalkylene group, a random adduct, or a combination of a block adduct and a random adduct. The order of addition of the oxyethylene group and the other oxyalkylene group may be any first. In one embodiment, the alkylene oxide adduct (A) of the amine compound is a random adduct of ethylene oxide and propylene oxide, that is, the polyoxyalkylene chain is a random adduct of oxyethylene groups and oxypropylene groups. This is preferable, and the releasability can be further improved.

In one embodiment, the amount of alkylene oxide added (average number of moles added) is preferably 100 to 600 mol, more preferably 120 to 450 mol, or even 150 to 300 mol, per mol of the amine compound. The amount of ethylene oxide added (average number of moles added) is preferably 80 to 570 mol, more preferably 100 to 400 mol, and may be 120 to 250 mol, per 1 mol of the amine compound. When ethylene oxide and propylene oxide are used in combination as the alkylene oxide, the ratio of the average number of moles added (ethylene oxide / propylene oxide) of both is preferably 3 to 15, and more preferably 4 to 10. Here, the average number of moles added can be determined by ¹ H-NMR (solvent: CDCl _3).

The method for adding the alkylene oxide is not particularly limited. For example, in the presence of the amine compound and the catalyst, the alkylene oxide is introduced into the reaction vessel at 70 to 120 ° C. and 0 to 0.3 MPa, and the amine compound is added. A known method such as a method of reacting with can be used. The catalyst is not particularly limited, and examples thereof include alkali metals such as potassium hydroxide and sodium hydroxide, and alkaline earth metals such as calcium hydroxide and magnesium hydroxide.

In one embodiment, the amine compound alkylene oxide adduct (A) preferably has a number average molecular weight (Mn) of 5,000 to 30,000. When the number average molecular weight is 5000 or more, it is possible to improve the releasability between the rubber and the mold after vulcanization, even though the amount used is small (for example, even when used at a low concentration). Further, when the number average molecular weight is 30,000 or less, it is possible to suppress an increase in the viscosity of the release agent and suppress a decrease in workability. The number average molecular weight is more preferably 6000 to 25000, still more preferably 7000 to 22000.

In one embodiment, the alkylene oxide adduct (A) of the amine compound preferably contains 50 to 95% by mass of an oxyethylene group. That is, the content of the oxyethylene group in the alkylene oxide adduct (A) of the amine compound is preferably 50 to 95% by mass. By increasing the content of the oxyethylene group in this way, it is possible to easily dissolve in water and improve the detergency, and in combination with the above setting of the molecular weight, the detergency and the releasability are further improved. Can be improved. The content of the oxyethylene group is more preferably 60 to 95% by mass, still more preferably 70 to 90% by mass. Here, the content of the oxyethylene group can be determined by ¹ H-NMR (solvent: CDCl _3).

The alkylene oxide adduct (A) of the amine compound according to a preferred embodiment has a number average molecular weight (Mn) of 5,000 to 30,000 and contains 50 to 95% by mass of an oxyethylene group. In a structure having a structure in which 4 to 8 polyoxyalkylene chains are bonded as described above, by setting the molecular weight to be high and the content of oxyethylene groups to be high in this way, excellent demolding can be performed even with a small amount of use. It can exhibit its properties and can be easily dissolved in water to improve its detergency. Moreover, since the detergency is excellent and the release agent can be removed in a short time, the productivity of the vulcanized rubber can be improved.

In one embodiment, the amine compound alkylene oxide adduct (A) preferably has an average hydroxyl value of 5 to 50 mgKOH / g. By setting it within such a range, the releasability and the detergency become more excellent. The average hydroxyl value is more preferably 8 to 40 mgKOH / g, still more preferably 10 to 35 mgKOH / g. Here, the average hydroxyl value can be measured according to JIS K0070.

The release agent for vulcanized rubber molding according to the present embodiment contains a surfactant (B) together with the alkylene oxide adduct (A) of the amine compound. By using the surfactant (B) in combination, the contact angle with the rubber can be reduced to improve the wettability, and the release agent can be adhered more uniformly, which leads to the improvement of the release property. ..

Examples of the surfactant (B) include a nonionic surfactant, an anionic surfactant, and an amphoteric surfactant, and any one or a combination of two or more of these can be used.

Examples of the nonionic surfactant include polyoxyalkylene alkyl ethers such as polyoxyalkylene octyl ether, polyoxyalkylene nonyl ether, polyoxyalkylene decyl ether, polyoxyalkylene dodecyl ether, and polyoxyalkylene tridecyl ether; Polyoxyalkylene phenols such as oxyalkylene alkyl phenyl ethers and polyoxyalkylene styrene phenyl ethers; Examples thereof include polyoxyalkylene fatty acid esters.

Examples of anionic surfactants include oil and fat fatty acid alkali metal salts such as potassium coconut oil, sodium coconut oil, potassium palm oil, and sodium palm oil; sodium lauryl sulfate, potassium lauryl sulfate, sodium decyl sulfate, and decyl. Examples thereof include alkyl sulfate alkali metal salts such as potassium sulfate, sodium dodecyl sulfate, and potassium dodecyl sulfate.

Examples of the amphoteric surfactant include coconut oil fatty acid amide propyl betaine, coconut oil fatty acid amide propyl dimethylamino acetate betaine, lauryl dimethyl amino acetate betaine, 2-alkyl-N-carboxymethyl-N-hydroxyethyl imidazolinium betaine, and the like. Betaine-type amphoteric surfactants such as laurylhydroxysulfobetaine and lauroylamide ethylhydroxyethylcarboxymethylbetaine hydroxypropyl phosphate; amino acid-type amphoteric surfactants such as β-sodium laurylaminopropionate; amines such as lauryldimethylamine oxide Oxide-type amphoteric surfactants and the like can be mentioned.

The surfactants listed above may be used alone or in combination of two or more. Preferred surfactants (B) include polyoxyalkylene alkyl ethers, polyoxyalkylene phenols, fat and oil fatty acid alkali metal salts, alkyl sulfate alkali metal salts, betaine-type amphoteric surfactants, and amine oxide-type amphoteric surfactants. At least one selected from the group of Further, since the contact angle with rubber is lower, an amphoteric surfactant is preferable as the surfactant (B).

The content of the surfactant (B) is not particularly limited, but is preferably 0.01 to 10 parts by mass with respect to 100 parts by mass of the alkylene oxide adduct (A) of the amine compound. With such a content, the contact angle with respect to the rubber becomes lower, and the releasability can be further improved. The content of the surfactant (B) is more preferably 0.03 part by mass or more, and further preferably 0.05 part by mass or more. The content of the surfactant (B) is more preferably 7 parts by mass or less, still more preferably 5 parts by mass or less.

The release agent for molding vulcanized rubber according to the present embodiment may be composed of the alkylene oxide adduct (A) of the amine compound and the surfactant (B), but is diluted with a solvent such as water. May be. It is preferably diluted with water, and the concentration of the alkylene oxide adduct (A) of the amine compound is preferably 5 to 70% by mass, more preferably 20 from the viewpoint of detergency and releasability. ~ 50% by mass.

The vulcanized rubber molding release agent according to the present embodiment may contain other components such as silicone as long as the effect is not impaired.

The mold release agent for molding vulcanized rubber according to the present embodiment can be used as a mold release agent for molding various vulcanized rubbers. For example, 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. It can be used for sulfide molding of known rubber such as rubber (FKM).

Vulcanization molding of rubber can be performed according to a conventional method. For example, by applying the mold release agent of the present embodiment to a mold and / or applying it to an unvulcanized rubber, the unvulcanized rubber and the mold can be formed. After applying the mold release agent to the contacted portion, the unvulcanized rubber may be attached to the mold and heated and vulcanized. After vulcanization, the vulcanized rubber is taken out from the mold, and the release agent adhering to the rubber surface is washed with water, warm water, or the like to obtain vulcanized rubber. The unvulcanized rubber includes, together with the above rubber, known additives such as a vulcanizing agent, a vulcanizing aid, a processing aid, a plasticizer, a process oil, carbon black, a white filler, and an antiaging agent. A rubber composition containing the above can be used.

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

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

(Number average molecular weight)
Measured by GPC method. The GPC apparatus and analytical conditions were as follows, and a standard sample calibrated with polyethylene glycol having a molecular weight of 327, 2000, 8250, and 19700 was used.
・ GPC device: System controller: SCL-10A (manufactured by Shimadzu Corporation)
・ Detector: RID-10A (manufactured by Shimadzu Corporation)
-Column: Shodex GPCKF-G, KF-803, KF802.5, KF-802, KF-801 connected (all manufactured by Showa Denko KK)
-Eluent: tetrahydrofuran-Sample injection: 0.5 wt% solution, 80 μL
・ Flow velocity: 0.8 mL / min
-Temperature: 25 ° C.

The raw materials used in the examples are as follows.

(A-1): Production Example 1
60 g (1 mol) of ethylenediamine and 3 g of potassium hydroxide were charged into a stainless steel autoclave, and the inside of the reactor was replaced 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 an internal pressure of 0.3 MPa or less. After completion of the introduction, the reaction was further carried out at 100 ° C. for 2 hours to obtain a propylene oxide (24 mol) / ethylene oxide (126 mol) random adduct (A-1) of ethylenediamine.

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, and EO (g) and EO (mol) indicate the amount of ethylene oxide used, both of which are amine compounds. (Ethylene oxide in A-1) The amount used per 1 mol. Further, EO (%) is the content (mass%) of the oxyethylene group in the obtained alkylene oxide adduct. Mn and OHV indicate the number average molecular weight and the average hydroxyl value (mgKOH / g) of the obtained alkylene oxide adduct, respectively. The same applies to the following (A-2) to (A-9).

(A-2) to (A-6): Production Examples 2 to 6
The same operations as in Production Example 1 were carried out except that ethylene oxide and propylene oxide were used in the amounts shown in Table 1, to obtain propylene oxide / ethylene oxide random adducts (A-2) to (A-6) of ethylenediamine. ..

(A-7): Production Example 7
60 g (1 mol) of ethylenediamine and 3 g of potassium hydroxide were charged into a stainless steel autoclave, and the inside of the reactor was replaced with nitrogen. The temperature was raised to 100 ° C., and 1798 g (31 mol) of propylene oxide was introduced while maintaining an internal pressure of 0.3 MPa or less. After the introduction was completed, the reaction was further carried out at 100 ° C. for 2 hours. Subsequently, 7172 g (163 mol) of ethylene oxide was introduced while maintaining an internal pressure of 0.3 MPa or less. After the introduction of ethylene oxide was completed, the reaction was carried out at 100 ° C. for 2 hours to obtain a propylene oxide (31 mol) -ethylene oxide (163 mol) block adduct (A-7) of ethylenediamine.

(A-8): Production Example 8
Using 103 g (1 mol) of diethylenetriamine instead of ethylenediamine, the same procedure as in Production Example 1 was carried out except that ethylene oxide and propylene oxide were used in the amounts shown in Table 1, and propylene oxide (31 mol) / ethylene oxide of diethylenetriamine was used. A (162 mol) random adduct (A-8) was obtained.

(A-9: Production Example 9)
The same procedure as in Production Example 1 was carried out except that propylene oxide and ethylene oxide were used in the amounts shown in Table 1, and propylene oxide (30 mol) / ethylene oxide (30 mol) random adduct (A-9) of ethylenediamine was added. Obtained.

(B-1): Polyoxyalkylene decyl ether (trade name: Neugen XL-1000, manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.)
(B-2): Polyoxyethylene styrenated phenyl ether (trade name: Neugen EA-167, manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.)
(B-3): Palm oil fatty acid potassium (B-4): Sodium lauryl sulfate (B-5): Lauryldimethylaminoacetic acid betaine (B-6): Palm oil fatty acid amide propyl betaine (B-7): Lauryldimethyl Amine oxide (C-1): Dimethylpolysiloxane (trade name: KF-96-20CS, manufactured by Shin-Etsu Chemical Co., Ltd.).

(Examples 1 to 19, Comparative Examples 1 and 2)
A mold release agent was obtained by mixing each raw material at the ratio (mass ratio) shown in Table 2 below. The following evaluation was performed using this release agent.

(Wetness)
Using ethylene propylene diene rubber (EPDM) or acrylonitrile-butadiene copolymer rubber (NBR), the contact angle was measured by the tangential method at 25 ° C. according to JIS R3257, and the wettability was evaluated according to the following criteria. The smaller the contact angle, the better the wettability.

A: Contact angle is less than 40 ° B: Contact angle is 40 ° or more and less than 50 ° C: Contact angle is 50 ° or more and less than 60 ° D: Contact angle is 60 ° or more.

(Removability)
An unvulcanized rubber (ethylene propylene diene rubber (EPDM) or acrylonitrile-butadiene copolymer rubber (NBR)) coated with a release agent was attached to a mold (120 mm × 120 mm × 2 mm). Subsequently, the vulcanization treatment was performed at 150 ° C. for 1 hour, and the vulcanized rubber was taken out from the mold. The workability at this time was defined as releasability, and Comparative Example 1 was used as a control for evaluation according to the following criteria. The results are shown in Table 2.

A: Workability is similar to that when dimethylpolysiloxane is used, and vulcanized rubber can be taken out from the mold. B: Workability is slightly inferior to that when dimethylpolysiloxane is used, but vulcanized rubber is removed from the mold. C: The workability is worse than when dimethylpolysiloxane is used, and the vulcanized rubber cannot be taken out from the mold.

(Cleanability)
The vulcanized rubber obtained in the evaluation of releasability was immersed in 2 L of water (temperature: 80 ° C.) for 30 seconds and taken out to confirm the sliminess of the surface of the vulcanized rubber. If there was slime, it was immersed in 2 L of newly prepared water (temperature: 80 ° C.) for 30 seconds, and the slime disappeared, or this operation was repeated up to a total of 3 times. Detergency was evaluated according to the following criteria. The results are shown in Table 2. If there is slime on the surface of the vulcanized rubber, the release agent remains, and if there is no slime, it indicates that no release agent remains.

A: No slime on the surface of the vulcanized rubber after the first immersion B: No slime on the surface of the vulcanized rubber after the second immersion C: No slime on the surface of the vulcanized rubber after the third immersion D: There is slime on the surface of the vulcanized rubber even after the third immersion.

As shown in Table 2, in Comparative Example 1 in which dimethylpolysiloxane was used as the release agent, the releasability was excellent, but the detergency was inferior. In Comparative Example 2, the alkylene oxide adduct of ethylenediamine was used alone, and it was inferior in wettability, releasability and detergency.

On the other hand, in Examples 1 to 19 in which the alkylene oxide adduct of ethylenediamine or diethylenetriamine and the surfactant are used in combination, the contact angle with the rubber is small and the wettability is excellent, and the wettability is as low as 10 to 30% by mass. Sufficient releasability could be exhibited even at the concentration used, and it was excellent in releasability and detergency. Further, from the comparison between Examples 1 to 4 and Examples 5 to 7, it was found that the amphoteric surfactant (B) is advantageous in terms of wettability. Further, from the comparison between Examples 18 and 5, 13 to 17 and 19, it was found that the random addition is more advantageous than the block addition in terms of releasability as the addition form of the alkylene oxide.

Claims (4)

Ri Na by adding an alkylene oxide to the amine compound having 4 to 8 active hydrogen atoms in the molecule, a number average molecular weight of Ru der 5,000 to 30,000, alkylene oxide adducts of the amine compound (A), and surfactant (B)
A mold release agent for vulcanized rubber molding containing. The vulture rubber molding according to claim 1, wherein the surfactant (B) is at least one selected from the group consisting of a nonionic surfactant, an anionic surfactant and an amphoteric surfactant. Release agent. The release for vulcanization rubber molding according to claim 1 or 2, wherein the surfactant (B) is contained in an amount of 0.01 to 10 parts by mass with respect to 100 parts by mass of the alkylene oxide adduct (A) of the amine compound. Molding agent. The release agent for vulcanized rubber molding according to any one of claims 1 to 3 , wherein the alkylene oxide adduct (A) of the amine compound contains 50 to 95% by mass of an oxyethylene group.