JPS643215B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for producing a vinyl chloride copolymer solution containing vinyl chloride, vinyl carboxylic acid ester, unsaturated carboxylic acid, and unsaturated carboxylic acid anhydride in specific proportions, and more specifically, Production of a four-component vinyl chloride copolymer solution with an average degree of polymerization of 100 to 400, characterized in that an unsaturated carboxylic acid and an unsaturated carboxylic acid anhydride are fractionally added when producing a combined solution by solution polymerization. Regarding the law. Conventionally, vinyl chloride copolymer solutions have been made by dissolving vinyl chloride copolymer powder in an organic solvent, or made by solution polymerization. Known examples include vinyl-vinyl acetate copolymer, vinyl chloride-vinyl acetate-vinyl alcohol copolymer, and vinyl chloride-vinyl acetate-maleic acid copolymer. These are mixed directly with surface coating materials for metals and paper, magnetic powder, thermosetting resins such as urethane resin, etc. to make magnetic paints, and this is applied to the surface of polyester resin sheets to create magnetic tapes, magnetic cards, etc. Used in magnetic recording media, etc. However, when using a vinyl chloride copolymer as described above for magnetic recording media, for example, vinyl chloride-vinyl acetate copolymer has no reactivity with urethane resin, and magnetic paint using this copolymer cannot be used as a base material. If applied, the coating will peel off, so it is not practical. In addition, vinyl chloride-vinyl acetate-vinyl alcohol terpolymer is preferable as a magnetic paint because of its affinity with magnetic powder and good reactivity with urethane resin, but the paint itself is
Workability is poor due to the short pot life.
That is, when this paint is applied to a substrate, its viscosity increases over time, making it difficult to prepare a large amount of the paint. In addition, the vinyl chloride-vinyl acetate-maleic acid terpolymer has a low maleic acid content of 1%,
There are drawbacks such as poor dispersibility of magnetic powder and short pot life due to rapid reaction with urethane resin, so there is a demand for a vinyl chloride copolymer suitable for magnetic coatings. The present inventor conducted research on a copolymer that has a long pot life and has excellent properties as a magnetic paint, and found that vinyl chloride, vinyl carboxylate ester, unsaturated We have found that it is sufficient to copolymerize carboxylic acid and unsaturated carboxylic acid anhydride in a specific ratio. Furthermore, such a copolymer cannot be obtained by the solution polymerization method in which the entire amount of unsaturated carboxylic acid and unsaturated carboxylic acid anhydride is added from the beginning, and unsaturated carboxylic acid and unsaturated carboxylic acid anhydride are added in portions or The present invention was developed based on the knowledge that it is necessary to add the compound later and to finish the addition by the time the polymerization rate reaches 60%. That is, the present invention involves solution polymerizing vinyl chloride, vinyl carboxylic acid ester, unsaturated carboxylic acid, and unsaturated carboxylic acid anhydride in a specific ratio to produce a vinyl chloride copolymer solution. By adding or post-adding acid anhydride, the dispersibility of the magnetic powder is good, and the reactivity with thermosetting resins such as urethane resins is suitable for making magnetic paints. We would like to provide a method for producing an excellent quaternary vinyl chloride copolymer solution that, when coated on a substrate to form a magnetic recording medium, provides a smooth coating film without blocking even when left under high temperature and high humidity. That is. The present invention involves copolymerizing four components of (A) vinyl chloride, (B) carboxylic acid vinyl ester, (C) unsaturated carboxylic acid, and (D) unsaturated carboxylic acid anhydride in a specific ratio,
A method for producing a vinyl chloride copolymer solution suitable for magnetic recording media with an average degree of polymerization of 100 to 400 by a solution polymerization method, in which an unsaturated carboxylic acid and an unsaturated carboxylic acid anhydride are added by fractionation or post-addition. It is characterized by Specific examples of monomers to be copolymerized with vinyl chloride of the present invention include vinyl acetate, vinyl propionate, vinyl versatate (trade name of Ciel Co., Ltd.) and the like as vinyl carboxylate esters. Vinyl acetate is preferred. The unsaturated carboxylic acid is selected from maleic acid, itaconic acid, fumaric acid, acrylic acid, methacrylic acid, etc. Among these, maleic acid is preferred. As the unsaturated carboxylic anhydride, maleic anhydride and itaconic anhydride are preferably used. In the copolymer of the present invention, vinyl chloride is contained in an amount of 50 to 80% by weight of the sum of vinyl chloride and carboxylic acid vinyl ester. If vinyl chloride exceeds 80% by weight based on the sum of vinyl chloride and carboxylic acid vinyl ester, the viscosity of the solution will increase due to mixing with magnetic powder, so it is necessary to lower the paint viscosity when applying the magnetic paint to the substrate. Large amounts of solvent must be used. On the other hand, if the amount of carboxylic acid vinyl ester exceeds 50% by weight, the strength of the coating film surface will be weak, and the coating film may peel or block, which is undesirable. Further, the unsaturated carboxylic anhydride is contained in an amount of 60 to 90% by weight of the sum of the unsaturated carboxylic acid and the unsaturated carboxylic anhydride. When the unsaturated carboxylic anhydride exceeds 90% by weight of the sum of the unsaturated carboxylic anhydride and the unsaturated carboxylic acid, the dispersibility of the magnetic powder decreases. On the other hand, if the unsaturated carboxylic acid exceeds 40% by weight, the reaction with the thermosetting resin is too rapid and the pot life becomes short. In addition, if the total amount of unsaturated carboxylic acid and unsaturated carboxylic acid anhydride is less than 1 per 100 of the total amount of vinyl chloride and carboxylic acid vinyl ester by weight,
The reactivity with the thermosetting resin is weak, and on the other hand, if it exceeds 5, the reactivity with the thermosetting resin is rapid and the pot life of the paint is short, making it impossible to put it into practical use. In addition, the average degree of polymerization of vinyl chloride copolymer is 100~
400 was selected because when applied to a substrate as a magnetic paint, if the average degree of polymerization is less than 100, the coating surface will be weak and impractical, and if it exceeds 400, the viscosity of the paint will be high, making it difficult to use. Applying concentrated solutions is difficult. The average degree of polymerization of the vinyl chloride copolymer is
Particularly preferred are those between 200 and 400. The copolymerization method according to the present invention is solution polymerization, and the solvent is preferably the same type of solvent as the solvent used for the magnetic paint from the viewpoint of economy and labor saving. That is,
There is no need for the conventional operation of dissolving powdered resin in a solvent. Examples of such solvents include esters such as ethyl acetate and butyl acetate, ketones such as acetone, methyl ethyl ketone and methyl isobutyl ketone, and aromatics such as xylene and toluene. As for the polymerization procedure, vinyl chloride and carboxylic acid vinyl ester are charged into a polymerization can, a conventional oil-soluble initiator is charged, and the mixture is heated and polymerized under pressure. Since unsaturated carboxylic acids and unsaturated carboxylic acid anhydrides have a faster reaction rate than other copolymerizable monomers, in order to obtain the four-component copolymer according to the present invention, monomers are added at the beginning or before the start of polymerization. As the polymerization progresses, the remainder is added in portions until the polymerization rate reaches 60%. If the entire amount of unsaturated carboxylic acid and unsaturated carboxylic acid anhydride is added at the start of polymerization, the resulting polymerization solution will become cloudy, the dispersibility of magnetic powder will be poor during the production of magnetic paint, and the pot life will be shortened.
The same applies when the polymerization rate exceeds 60%. As the thermosetting resin used for the magnetic recording medium, urethane resin, epoxy resin, and phenol resin can be used, but when the substrate is a polyester resin, urethane resin is preferable. The present invention will be specifically explained below with reference to Examples. Example 1 130 parts by weight of vinyl chloride, 70 parts by weight of vinyl acetate,
105 parts by weight of methyl ethyl ketone, 45 parts by weight of toluene and 2 parts by weight of benzoyl peroxide were charged into an autoclave, and polymerization was started at 55°C. Vinyl chloride
When the polymerization rate of vinyl acetate reached 10%, 1/6 of a mixed solution consisting of 4.5 parts by weight of maleic anhydride, 1.5 parts by weight of maleic acid, and 30 parts by weight of methyl ethyl ketone was added. Remaining 5/6 until the above polymerization rate reaches 60%.
Added in portions. The mixture was polymerized to a polymerization rate of 90% and cooled, and the resulting resin solution having a resin content of about 50% by weight was taken out. As a result of analysis, this resin composition was a copolymer of 70 parts by weight of vinyl chloride, 30 parts by weight of vinyl acetate, 2.3 parts by weight of maleic anhydride, and 0.7 parts by weight of maleic acid with a degree of polymerization of 250. The results of testing this copolymer according to the measurement method and criteria described below showed that it has excellent compatibility, has a gloss of 93% when made into a magnetic paint, and has a pot life.
After 150 hours, there was no blocking property and the adhesion was good. Measurement method and criteria 1 Compatibility Copolymers obtained in Examples and Comparative Examples (solid content equivalent) 100 parts by weight Product name Coronate L (urethane resin)
A mixed solution consisting of 20 〃 methyl ethyl ketone and 300 〃 was prepared, and transparent products were marked as ○, translucent products as △, and opaque products as ×. 2 Copolymers obtained in gloss examples and comparative examples (solid content equivalent) 100 parts by weight Magnetic iron oxide powder 400 〃 Methyl ethyl ketone 300 〃 Methyl isobutyl ketone 300 〃 Toluene 300 〃 Product name Coronate L (urethane resin)
20 〃 Trade name: lecithin (soybean oil) 〃 A magnetic paint obtained by thoroughly kneading a mixture consisting of 2 〃 is applied to a polyester film base to a dry film thickness
Apply to a thickness of 10μ and dry. The reflectance of the magnetic coating film at a 60° reflection angle is measured using a gloss meter. 3 Pot life of magnetic paint The same magnetic paint used for the above gloss measurement was collected in a small bottle, and the time until the paint lost its fluidity (gelatinized) in a constant temperature bath at 25°C was measured to determine the pot life. 4 Blocking property The same magnetic paint used for the above gloss measurement was coated on a polyester film base, and then 2 layers were coated.
Apply a load of Kg/cm ² and leave the film at 60℃ and 90% humidity for 24 hours, then remove the film. Those that can be easily peeled off are marked as ○, those that are slightly sticky are marked as △, and those that are sticky are marked as ×. 5. Adhesion The same magnetic paint used in the above gloss measurement was applied to a polyester film substrate, dried, and Cellotape (trade name) was applied, rubbed strongly with a finger, and then peeled off. At this time, the adhesion was rated as 〇 if the magnetic coating film did not adhere to the cellophane tape, and the adhesiveness was rated as × if the coating film adhered and peeled off. In addition, the following examples and comparative examples were also tested according to the above method. Comparative Example 1 A copolymer solution was obtained in the same manner as in Example 1, except that the entire amount of maleic anhydride and maleic acid was charged before the start of polymerization. In this case, the polymerization solution was cloudy. When we produced magnetic paint using this, the magnetic powder was not sufficiently dispersed and the pot life was only 24 hours.
It was time. Example 2 and Comparative Example 2 A copolymer having the composition shown in Table 1 was obtained in the same manner as in Example 1 except that the types of monomers and the charging ratio were variously changed, and the physical properties thereof are also listed. Comparative Example 3 Copolymerization was carried out in the same manner as in Comparative Example 1 except that 135 parts by weight of methyl ethyl ketone was used. The obtained copolymer was cloudy. The magnetic paint using this material had the same dispersibility of magnetic powder and pot life as Comparative Example 1. Example 3 130 parts by weight of vinyl chloride, 70 parts by weight of vinyl acetate,
105 parts by weight of methyl ethyl ketone, 45 parts by weight of toluene, 2 parts by weight of benzoyl peroxide, maleic anhydride
1.13 parts by weight and 0.37 parts by weight of maleic acid were charged into an autoclave, and polymerization was started at 55°C. When the vinyl chloride-vinyl acetate polymerization rate reached 10%, 1/3 of a mixed solution consisting of 3.39 parts by weight of maleic anhydride, 1.11 parts by weight of maleic acid, and 30 parts by weight of methyl ethyl ketone was added. Until the remaining 2/3 reaches a polymerization rate of 30%,
Added in portions. The mixture was polymerized to a polymerization rate of 90% and cooled, and the resulting colorless and transparent resin solution was taken out. The resin composition and degree of polymerization were the same as in Example 1. The test results showed compatibility: 91% gloss when made into magnetic paint.
Pot life over 240 hours, blocking resistance 〇,
The adhesion was 0. Example 4 130 parts by weight of vinyl chloride, 70 parts by weight of vinyl acetate,
105 parts by weight of methyl ethyl ketone, 45 parts by weight of toluene, and 2 parts by weight of benzoyl peroxide were charged into an autoclave, and polymerization was started at 55°C. Vinyl chloride
When the polymerization rate of vinyl acetate reached 10%, 1/4 of a mixed solution consisting of 4.5 parts by weight of maleic anhydride, 1.5 parts by weight of maleic acid, and 30 parts by weight of methyl ethyl ketone was added. The remaining 3/4 was added in portions until the polymerization rate reached 40%. The mixture was polymerized to a polymerization rate of 90% and cooled, and the resulting colorless and transparent resin solution was taken out. The resin composition and degree of polymerization were the same as in Example 1. The test results were compatibility 〇, gloss when made into magnetic paint 93%,
Pot life over 240 hours, blocking resistance 〇,
The adhesion was 0. Example 5 The same procedure as Example 1 was carried out except that itaconic anhydride was used instead of maleic anhydride. The composition of the obtained resin was 70 parts by weight of vinyl chloride,
30 parts by weight of vinyl acetate, 4.0 parts by weight of itaconic anhydride,
The degree of polymerization was 220 at 0.7 parts by weight of maleic acid. The compatibility of this is 〇, and the gloss after making it into a magnetic paint is 95.
%, pot life 180 hours, blocking property and adhesion were both 0. Example 6 Example 5 was repeated except that itaconic acid was used instead of maleic acid. The composition of the obtained resin was 70 parts by weight of vinyl chloride,
30 parts by weight of vinyl acetate, 4.0 parts by weight of itaconic anhydride,
The degree of polymerization was 200 at 1.0 parts by weight of itaconic acid. The compatibility of this is 〇, and the gloss after making it into a magnetic paint is 92.
%, pot life 130 hours, blocking property and adhesion were both 0. Example 7 Polymerization was carried out in the same manner as in Example 1 until the polymerization rate reached 10%, and when the polymerization rate reached 10%, a solution of 1.0 parts by weight of maleic anhydride dissolved in 5 parts by weight of methyl ethyl ketone was added, Next, a solution of 3.5 parts by weight of maleic anhydride dissolved in 15 parts by weight of methyl ethyl ketone (hereinafter referred to as solution A) and a solution of 1.5 parts by weight of maleic acid dissolved in 10 parts by weight of methyl ethyl ketone (hereinafter referred to as solution B) were mixed at a polymerization rate of 60%. During this period, they were simultaneously added in portions and polymerized to a polymerization rate of 90% to obtain a polymer solution. Separately, the maleic anhydride solution was added at the above polymerization rate of 10%, and the A solution and B solution were added to the polymerization rate of 60%.
%, respectively, and a polymer solution was obtained in the same manner. The copolymer compositions of both solutions were substantially the same as in Example 1, and the various test results were also substantially the same.

【table】

【table】

[Table] (Note) The compound symbols in the table represent the following.
a: Vinyl acetate b: Vinyl propionate c
: Maleic acid d : Fumaric acid
e: itaconic acid f: acrylic acid g: vinyl alcohol

Claims (1)

[Scope of Claims] 1 A four-component polymer of (A) vinyl chloride (B) carboxylic acid vinyl ester (C) unsaturated carboxylic acid and (D) unsaturated carboxylic acid anhydride, wherein (A) is ( Contains 50-80% by weight of A) + (B), contains 60-90% by weight of (C) + (D), and (C) per 100 parts by weight of (A) + (B) When producing a resin solution for magnetic coatings whose main component is a copolymer with an average degree of polymerization of 100 to 400, which contains 1 to 5 parts by weight of +(D), vinyl chloride monomer and vinyl carboxylic acid ester are placed in a polymerization can in advance. Prepare the monomer, organic solvent and oil-soluble polymerization initiator, and add unsaturated carboxylic acid and unsaturated carboxylic acid anhydride in portions, or
Alternatively, a resin solution for magnetic coatings is characterized in that a part of the unsaturated carboxylic acid and the unsaturated carboxylic anhydride are added before the start of polymerization, the remaining part is added in portions, and the addition is completed by the time the polymerization rate reaches 60%. manufacturing method.