JPH0255848B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a magnetic recording medium such as a magnetic tape for magnetic recording, for example. Conventionally, magnetic recording media such as magnetic tapes contain mineral oil, silicone oil, metal soap, higher alcohol, fatty acid, etc. in the magnetic layer of the magnetic recording medium, which is made of magnetic powder, binder, etc., in order to improve its running properties. Generally, magnetic recording media containing lubricants such as silicon compounds, etc., are blended with lubricants such as silicon compounds, etc., but magnetic recording media containing this type of lubricant have no problems with runnability or steel durability at room temperature and humidity, but When used under high temperature and high humidity conditions, running friction increases, resulting in poor running performance, and still images lose sharpness after about 30 minutes, resulting in a lack of steel durability. The present invention solves the disadvantages of conventional magnetic recording media by using a new lubricant, and provides a magnetic recording medium that has excellent runnability and steel durability even under high temperature and high humidity conditions. The purpose is to have the following general formula in the magnetic layer:

[Formula] or

It is made by blending an acetylated monoglyceride which is 60-100% acetylated from the monoglyceride represented by the formula: (wherein R represents an alkyl group having 11 to 21 carbon atoms). The reason why R in the monoglyceride represented by this general formula is limited to an alkyl group having 11 to 21 carbon atoms is because when R is an alkyl group having 10 or less carbon atoms, the acetylated monoglyceride is bonded into the magnetic layer. This is because the acetylated monoglyceride acts as a plasticizer on the resin blended as an agent, reducing the mechanical strength of the resin, and if R is an alkyl group with more than 21 carbon atoms, the acetylated monoglyceride may not work with the resin. This is because they exist separately, increasing the adhesion of the magnetic layer surface, causing large friction, and impairing the durability of the steel. In addition, the acetylation rate of the acetylated monoglyceride obtained by acetylating such monoglyceride is 60 to 100%.
If the acetylation rate is ~100%, good runnability and steel durability under high temperature and high humidity conditions can be obtained, but if the acetylation rate is less than 60%, such good runnability and steel durability cannot be obtained. be. Here, the acetylation rate of the acetylated monoglyceride is indicated by what percentage of the hydroxyl groups of the monoglyceride are acetylated by acetic acid. The amount of acetylated monoglyceride to be incorporated into the magnetic layer is generally preferably about 0.4 to 5% by weight based on the weight of the magnetic powder in the magnetic layer. The magnetic recording medium is produced by applying a magnetic paint containing the acetylated monoglyceride together with magnetic powder, a binder, etc. to the surface of a non-magnetic substrate such as a base film made of polyethylene terephthalate, polyester, etc. to form a magnetic layer. Obtained by forming. Hereinafter, the present invention will be explained based on Examples and Comparative Examples. Example 1 Acetylated monoglyceride was obtained by 100% acetylation of monoglyceride obtained by monoesterifying glycerin with lauric acid (C ₁₁ H ₂₃ COOH),
Add this 2 parts by weight to 100 parts by weight of _C0 -containing γ-Fe ₂ O ₃ 3 parts by weight of Al ₂ O ₃ 11 parts by weight of salt-vinyl acetate copolymer (trade name: VAGH) 11 parts by weight of polyurethane 5 parts by weight of carbon Lecithin 1 part by weight 130 parts by weight of methyl ethyl ketone and 130 parts by weight of toluene were mixed to obtain a magnetic paint, and the magnetic paint was applied onto a long polyester film 12 cm wide and 14 μm thick to a width of 10 cm and a thickness of 4 μm after drying. orientation,
1/2 after drying, calendering, shredding, etc.
An inch-wide recording magnetic tape was obtained. sample this
It was ranked No.1. Example 2 A recording magnetic tape was obtained in the same manner as in Example 1, except that an acetylated monoglyceride obtained by 60% acetylation of the monoglyceride of Example 1 was used in place of the acetylated monoglyceride of Example 1, and this was used as a sample. It was set as No.2. Example 3 A recording magnetic tape was obtained in the same manner as in Example 1, except that an acetylated monoglyceride obtained by 70% acetylation of the monoglyceride in Example 1 was used in place of the acetylated monoglyceride in Example 1, and this was used as a sample. It was set as No.3. Example 4 In place of the acetylated monoglyceride in Example 1, monoglyceride obtained by monoesterifying glycerin with myristic acid (C ₁₃ H ₂₇ COOH) was used at 100%
A recording magnetic tape was obtained in the same manner as in Example 1, except that acetylated monoglyceride with % acetylation was used, and this was designated as Sample No. 4. Example 5 In place of the acetylated monoglyceride of Example 1, monoglyceride obtained by monoesterifying glycerin with palmitic acid (C ₁₅ H ₃₁ COOH) was used at 100%
A recording magnetic tape was obtained in the same manner as in Example 1, except that acetylated monoglyceride having % acetylation was used, and this was designated as Sample No. 5. Example 6 Same as Example 1 except that instead of the acetylated monoglyceride of Example 1, an acetylated monoglyceride obtained by monoesterifying glycerin with behenic acid (C ₂₁ H ₄₃ COOH) was used, which was 100% acetylated. A recording magnetic tape was obtained, which was designated as Sample No. 6. Comparative Example 1 A recording magnetic tape was obtained in the same manner as in Example 1, except that instead of the acetylated monoglyceride in Example 1, an acetylated monoglyceride obtained by 50% acetylation of the monoglyceride in Example 1 was used, and this was used as a sample. It was set as No.7. Comparative Example 2 Same as Example 1 except that in place of the acetylated monoglyceride of Example 1, an acetylated monoglyceride obtained by 100% acetylation of monoesterified monoglyceride of glycerin with capric acid (C ₉ H ₁₉ COOH) was used. A recording magnetic tape was obtained, which was designated as Sample No. 8. Comparative Example 3 In place of the acetylated monoglyceride of Example 1, monoglyceride obtained by monoesterifying glycerin with lignophosphoric acid (C ₂₃ H ₄₇ COOH) was used at 100%
A recording magnetic tape was obtained in the same manner as in Example 1, except that acetylated monoglyceride with % acetylation was used, and this was designated as Sample No. 9. For each of the samples No. 1 to 9 obtained in this way, 23℃-
The friction coefficient (μ) and steel durability (minutes) were measured under the conditions of 50%RH and 40°C-85%RH. The measurement results are shown in the table below.

[Table] The coefficient of friction was determined by running each sample tape at a speed of 3.34 cm/sec between a pull-out reel and a take-up reel while winding it around a cylinder interposed between them at a contact angle θ. Tape tension T ₁ on drawer side
and the tape tension T ₂ on the winding side were measured, respectively, and calculated using Euler's equation below. μ=1/θlogT ₂ /T _1Also , steel durability is VHS video tape recorder (manufactured by Matsushita Electric Industrial Co., Ltd., McLeod NV
A constant video signal was recorded on each sample tape using a video camera (Model -310), which was then played back as a still image, and the time taken until the played image lost its sharpness was defined as the steel durability. As is clear from the above table showing the measurement results of the friction coefficient and steel durability of each sample tape of the Examples and Comparative Examples, the magnetic recording medium of the present invention can be used under the normal conditions of 23°C and 50% RH. It was confirmed that the steel has excellent runnability and steel durability not only under low temperature conditions, but also under high temperature and high humidity conditions of 40℃-85%RH.

Claims (1)

[Claims] 1. A monoglyceride represented by the general formula [Formula] or [Formula] (wherein R represents an alkyl group having 11 to 21 carbon atoms) is acetylated by 60 to 100% in the magnetic layer. A magnetic recording medium containing acetylated monoglyceride.