JPH02192012A - Magnetic recording medium - Google Patents

Abstract

PURPOSE:To improve electromagnetic conversion characteristics, the dispersibility of fine ferromagnetic powder and the storage stability of a magnetic coating compd. by incorporating a specific compd. as a binder into a magnetic layer and irradiating the layer with radiations. CONSTITUTION:The magnetic layer of the magnetic recording medium contains respectively >=1 kinds of the compds. among the groups indicated by the compds. obtd. by adding a polybasic unsatd. acid or unsatd. acid and polybasic acid to epoxy group-contg. vinyl chloride copolymers and polyurethane compds. contg. a CO2H group and carbon-carbon unsatd. bond as the binder. Further, the magnetic layer is irradiated with the radiations. The excellent dispersibility of the fine ferromagnetic powder and the good electromagnetic conversion characteristics are obtd. in this way; further, the magnetic coating compd. has the excellent storage stability.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to magnetic recording media such as video tapes, audio tapes, computer tapes, and floppy disks.

[Conventional technology]

Magnetic recording media that are currently widely used include thermoplastic binders such as vinyl chloride-vinyl acetate resin, vinyl chloride-vinylidene chloride resin, cellulose resin, acetal resin, urethane resin, and acrylonitrile butadiene resin. There is a method of using resins alone or in combination, but this method has the disadvantage that the abrasion resistance of the magnetic layer is poor and the running path of the magnetic tape is contaminated.

Also known are a method using a thermosetting resin such as a melamine resin or a urea resin, or a method in which a crosslinkable binder such as an isocyanate compound or a compound having an epoxy ring is added to the thermoplastic resin through a chemical reaction. However, when the above-mentioned crosslinking binder is used, (1) there is a problem in the storage stability of the liquid in which magnetic particles are dispersed, and the uniformity of the physical properties of the magnetic coating liquid and, by extension, the homogeneity of the magnetic recording medium cannot be maintained; 2) A heat treatment step is indispensable for curing the coating film after application and drying, and it also has disadvantages such as requiring a long time.

In order to prevent these drawbacks, methods for manufacturing magnetic recording media using acrylic ester oligomers and monomers as binders and curing them by irradiation with radiation after drying have been proposed in Japanese Patent Publication No. 47-12423 and Japanese Patent Application Laid-open No. 47-13639. , JP-A-47-15104, JP-A-50-77433
No., JP-A-5625231, JP-A-61-84207
No. 61-106605 and other publications. However, the manufacturing methods disclosed in the above-mentioned publications have not been able to produce magnetic recording media with advanced electromagnetic conversion characteristics and durability.

[Problem to be solved by the invention]

In recent years, there has been a demand for higher image quality in magnetic recording media.

This requires closer contact between the magnetic layer surface and the video head and audio head.
It is important to improve the surface smoothness of the magnetic recording medium and to further dramatically improve the dispersibility of the ferromagnetic fine powder. On the other hand, the smoother the surface of the magnetic layer, the greater the friction in the running system inside the video tape recorder.
As running tension increases, magnetic recording media are required to have increasingly severe running durability. For this reason,
Conventional manufacturing methods for magnetic recording media have not yielded magnetic recording media that have the smoothness of the surface of the magnetic layer, the dispersibility of the ferromagnetic fine powder, and the running durability.

The present inventors have developed conventional techniques such as a method using a thermoplastic resin or a thermosetting resin, a method of adding a crosslinkable binder by the above-mentioned chemical reaction, and a method of using a hardenable binder by radiation crosslinking. The present invention was achieved as a result of intensive research to improve the drawbacks.

Therefore, the objects of the present invention are to provide characteristics that could not be achieved with conventional magnetic recording media, namely: 1) excellent electromagnetic conversion characteristics; 2)
The object of the present invention is to provide a magnetic recording medium in which ferromagnetic fine powder has excellent dispersibility, 3) magnetic coating liquid has good storage stability and uniform performance, and 4) excellent running durability.

[Means and effects for solving the problem] The above problems can be solved by the method described below. That is, the present invention provides a magnetic recording medium mainly consisting of a non-magnetic support and a magnetic layer, wherein the magnetic layer contains one or more compounds each of the groups shown in (A) and (B) below, and is further resistant to radiation. The problem is solved by a magnetic recording medium characterized by being irradiated.

(A) A compound obtained by adding a polybasic unsaturated acid, or an unsaturated acid and a polybasic acid to an epoxy group-containing vinyl chloride copolymer.

(B) A polyurethane compound containing a CO2H group and a carbon-carbon unsaturated bond.

The epoxy group-containing vinyl chloride copolymer that is the base of the vinyl chloride compound (A) used in the present invention is glycidyl ethers of unsaturated alcohols such as acrylic glycidyl ether, methacryl glycidyl ether, and vinyl glycidyl ether, butadiene monoxide, etc. Copolymerize epoxy group-containing monomers such as epoxide olefins such as , vinylcyclohexene monooxide, and 2-methyl-56-nipoxyhexene with vinyl chloride and, if necessary, monomers such as vinyl acetate, vinyl propionate, maleic acid, and vinylidene chloride. It can be obtained by The synthesis method is disclosed, for example, in JP-A-61-106605.

The epoxy group content of the obtained pace polymer was 0.5w
t% or more is preferable. If it is less than 0.5 wt%, the amount of carbon-carbon double bonds introduced by the addition of an acid as described below will be small, resulting in insufficient radiation curability.

Examples of polybasic unsaturated acids used in the present invention include maleic acid, citraconic acid, fumaric acid, mesaconic acid, hymic acid, and itaconic acid, with maleic acid being particularly preferred.

If the unsaturated acid is monobasic, a polybasic acid must be used in combination to impart dispersibility to the ferromagnetic fine powder.

Monobasic unsaturated acids include halogen-substituted (meth)acrylic acids such as (meth)acrylic acid and chloroacrylic acid;
Vinyl sulfonic acid, methylvinyl sulfonic acid, (meth)
Acrylic sulfonic acid, styrene sulfonic acid, ethyl (meth)acrylic acid-2-sulfonate, 2-acrylamido-2-methylpropanesulfonic acid, 3-allyloxy-2
Unsaturated sulfonic acids such as hydroxypropenesulfonic acid; Unsaturated monoesters of sulfuric acid such as 2-ethyl (meth)acrylate sulfate and 3-allyloxy-2-hydroxypropane sulfate; di-2-(meth)acryloxyethyl Examples include unsaturated diesters of phosphoric acid such as acid phosphate.

Furthermore, examples of polybasic saturated acids among polybasic acids include polycarboxylic acids such as malonic acid, succinic acid, phthalic acid, and trimellitic acid; and sulfocarboxylic acids such as sulfobenzoic acid and sulfosalicylic acid. can give.

The thus obtained compound (8) preferably contains -COOH in an acid value of 1 to 100, more preferably 3 to 20, in order to improve the dispersibility of the ferromagnetic fine powder.

The number of carbon-carbon unsaturated bonds per molecule is preferably 1.5 to 20, more preferably 2 to 15. Outside this range, curing properties are poor and durability is poor. The number average molecular weight is preferably 5,000 to 100,000, more preferably 10,000 to 50,000.

Below this range, durability will be insufficient, and above this range, the viscosity will be high and the dispersibility of the ferromagnetic fine powder will deteriorate.

The urethane (meth)acrylates (B) containing a COz H group used in the present invention may have a main chain skeleton of polyester, polyether, or polyester ether (specific examples of dibasic acids used therein). Oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, sebacic acid, dodecanedioic acid, maleic acid, fumaric acid, itaconic acid, trimethyladipic acid, hexahydrophthalic acid, tetrahydrophthalic acid, phthalic acid, isophthalic acid. Acids, terephthalic acid, naphthalene dicarboxylic acid, etc. can be used.As dihydric alcohols, ethylene glycol, trimethylene glycol, tetramethylene glycol, pentamethylene glycol, hexamethylene glycol, octamethylene glycol, diethylene glycol, triethylene glycol, tetra Ethylene glycol, 2,2-dimethylpropane-1,3-diol, 2,2-diethylpropane-1,3-diol, cyclohexane-13-diol, cyclohexane-1,
4-diol, cyclohexane-1゜4-dimetatool, cyclohexane-13-dimetatool, 2,2-bis(4-hydroxyethoxy-cyclohexyl)propane, 2,2-bis(4-hydroxyethoxy-phenyl)
Propane, 2,2-bis(4-hydroxyethoxyethoxy-phenyl)propane, etc. can be used. Also γ−
It is also possible to use a lactone-based polyester skeleton made of butyrolactone, δ-valerolactone, ε-caprolactone, or the like. Isocyanates that form urethane bonds include 2,4-tolylene diisocyanate, 2
．． 6-1-lylene diisocyanate, 1.3-xylylene diisocyanate, 1. ．． 4-xylylene diisocyanate, 1゜5-naphthalene diisocyanate, m-phenylene diisocyanate, p-phenylene diisocyanate, 3,3-dimethylphenylene diisocyanate, 44-diphenylmethane diisocyanate, 3.3-
Polyvalent isocyanates such as methyl-4,4-diphenylmethane diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, dicyclohexylmethane diisocyanate, and tolylene diisocyanate triadduct of trimethylolpropane can be used. Further, a part of the dibasic acid and dihydric alcohol may be replaced with trivalent or higher acid and alcohol. The CO□H group and the acryloyl group may be located at the terminal or side chain of the polyurethane. The method for introducing these groups is as follows: 1) Incorporate one or more of trivalent or higher acid, alcohol, or isocyanate into the urethane skeleton, and add these to the urethane that has CO□H groups, OH groups, or NGO groups remaining in the side chains. 2) urethane having an isocyanate group at the end has at least one CO, H group, (meth)acryloyl group, and OH group. It can be obtained by reacting hydrogen compounds.

Examples of synthesis disclosures include JP-A-60-116316 and JP-A-61-222028. The compound (B) used in this patent is not limited to the range disclosed in this patent.

The preferred oxidation of the urethane (meth)acrylate used in the present invention is 1 to 100, more preferably 3 to 100.
20, more preferably 5-15. The number average molecular weight is i, ooo to 10o.

000, preferably 2,000 to 50,000, particularly preferably 3,000 to 30,000. If the acid value is out of this range, the dispersibility of the ferromagnetic fine powder will be poor, leading to a decrease in electromagnetic conversion characteristics and deterioration in durability.

Moreover, the average content of (meth)acryloyl groups is 1.5 to 10, preferably 2 to 8, per molecule.

When the molecular weight is less than 1000, the magnetic layer of the obtained magnetic recording medium becomes too strong, which tends to cause cracks when bent, and the magnetic recording medium tends to curl due to curing shrinkage after irradiation with radiation. . On the other hand, the molecular weight is 10
If it exceeds 0,000, the solubility of urethane (meth)acrylate in solvents tends to be poor, which not only makes handling inconvenient, but also deteriorates the dispersibility of the magnetic material and requires a large amount of energy for curing. Undesirable.

Furthermore, vinyl monomers can be added to the present invention. Vinyl monomers include compounds that can be polymerized by radiation irradiation and have one or more carbon-carbon unsaturated bonds in the molecule, such as (meth)acrylic esters, (meth)acrylamides, allyl Compound,
Examples include vinyl ethers, vinyl esters, vinyl joint compounds, N-vinyl compounds, styrenes, acrylic acid, methacrylic acid, crotonic acids, itaconic acids, and olefinic acids. Among these, preferred are the following compounds containing two or more methacryloyl groups. Specifically, diethylene glycol di(meth)acrylate, triethylene glycol di(meth)
(meth)acrylate neck of polyethylene glycol such as acrylate, tetraethylene glycol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, dipentaerythritol hexa(meth)acrylate , dipentaerythritol hexa(meth)acrylate, tris(β-(meth)acryloyloxyethyl)isocyanurate-1~, his(β-(meth)acryloyloxyethyl)isocyanurate, or polyisocyanate(2,4- Tolylene diisocyanate, 2゜6-tolylene diisocyanate, 1,3-xylylene diisocyanate 1-.1,4-xylylene diisocyanate, 1,5-naphthalene diisocyanate, m-phenylene diisocyanate, p-phenylene diisocyanate, 3, 3-dimethylphenylene diisocyanate 1-1
4.4-diphenylmethane diisocyanate, 3.3-
Dimethyl-4゜4-diphenylmethane diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, cyclohexylmethane diisocyanate-1
-, tolylene diisocyanate triadduct of trimethylolpropane) and hydroxy(meth)acrylate compound (2-hydroxyethyl(meth)acrylate, 2-
hydroxypropyl (meth)acrylate, etc.), or other difunctional or higher functional poly(meth)acrylate, etc.)
There are acrylates, etc. These monomers may be used alone or in combination of two or more.

The preferred composition ratio of the compound represented by (A) and the compound represented by (B) is 20 to 90 parts by weight/8.
0 to 10 parts by weight, particularly preferably 30 to 80 parts/70 to
There are 20 copies. If the ratio of the compound represented by (8) is less than this ratio or the ratio of the compound represented by (B) is less than this ratio, durability cannot be obtained. Further, the amount of the vinyl monomer added is preferably 50 parts by weight or less based on the total parts by weight of the compounds represented by (^) and (B). If the ratio is higher than this, the amount of radiation required for polymerization becomes undesirable, and the magnetic recording medium may curl or may not have sufficient durability.

As the ferromagnetic fine powder used in the present invention, ferromagnetic iron oxide fine powder, CO-doped ferromagnetic iron oxide fine powder, ferromagnetic chromium dioxide fine powder, ferromagnetic alloy powder, barium ferrite, etc. can be used. It is effective that the acicular ratio of ferromagnetic iron oxide and chromium dioxide is about 2/1 to 20/1, preferably 5/1 or more, and the average major axis diameter is about 0.2 to 2.0 μm.

The ferromagnetic alloy powder has a metal content of 75 wt% or more, and 80 wt% or more of the metal content is a ferromagnetic metal (i.e., Fe, Co,
These are particles of Ni, Fe-Ni, Co-NiFe-Co-N1) with an average major axis diameter of about 1.0 μm or less. What is particularly effective in the present invention is that it is difficult to disperse the ferromagnetic fine powder.
It is a fine particle ferromagnetic alloy powder with a specific surface area of 30, preferably 45 rrr/g or more.

Organic solvents used for dispersion and application of magnetic coating liquid include acetone, methyl ethyl ketone, methyl isobutyl ketone,
Ketones such as cyclohexanone; Nistyls such as methyl acetate, ethyl acetate, butyl acetate, ethyl lactate, glycol acetate monoethyl ether; ethyl ether, glycol dimethyl ether, glycol monoethyl ether,
Ethers such as dioxane and tetrahydrofuran; aromatic hydrocarbons such as henzene, toluene, and xylene; methylene chloride, ethylene chloride, carbon tetrachloride,
Chlorinated hydrocarbons such as chloroform, ethylene chlorohydrin, and dichlorobenzene can be selected and used.

Further, additives such as a lubricant, an abrasive, a dispersant, an antistatic agent, and a rust preventive may be added to the magnetic coating liquid of the present invention. In particular, lubricants include saturated and unsaturated higher fatty acids with 12 or more carbon atoms, fatty acid esters, higher fatty acid amides, higher alcohols, silicone oils, mineral oils, vegetable oils, fluorine compounds, etc., and these are used when preparing magnetic coating liquids. It may be added, or it may be dissolved in an organic solvent after drying or irradiation with radiation, or it may be directly applied to the surface of the magnetic layer.
May be sprayed.

Materials for the support to which the magnetic coating liquid is applied include polyesters such as polyethylene terephthalate 1-1 and polyethylene 2,6 naphthalate; polyolefins such as polyethylene and polypropylene, cellulose derivatives such as cellulose triacetate, polycarbonate 1, and polyimide. , plastics such as polyamideimide, non-magnetic metals such as aluminum, copper, tin, zinc or non-magnetic alloys containing these, and plastics with metals such as aluminum bonded thereto may also be used depending on the purpose.

In addition, the forms of non-magnetic supports include films, tapes, sheets,
It may be a disk, card, drum, etc., and various materials are selected depending on the form as necessary.

In addition, the support of the present invention can be used on the side on which a magnetic layer is provided for the purpose of preventing static electricity, preventing transfer of the surface roughness of the support to the magnetic layer, preventing wow-flush, improving the strength of magnetic recording media, and making the back surface matte. A so-called back coat may be applied to the opposite side (back side).In the present invention, it is preferable to irradiate radiation after applying magnetic paint and calendering. is also possible. Alternatively, it is also possible to irradiate one more time.

The radiation irradiated to the magnetic layer of the present invention includes electron beam, T
Although rays, β rays, ultraviolet rays, etc. can be used, electron beams are preferable. As the electron beam accelerator, a scanning method, double scanning method, curtain beam method, broad beam curtain method, etc. can be adopted.

As for the electron beam, the accelerating voltage is 100 to 1000 KV, preferably 150 to 300 KV, and the absorbed dose is 1
~20 Mr a d, preferably 3-15 Mr a d
It is. When the accelerating voltage is less than 100 KV, the amount of energy transmitted is insufficient, and when it exceeds 1000 KV, the efficiency of energy used in polymerization decreases, making it uneconomical. If the absorbed dose is less than IMrad, the curing reaction will be insufficient and the strength of the magnetic layer will not be obtained, and if it exceeds 20 Mrad, the energy efficiency used for curing will decrease, the irradiated object will generate heat, and especially the plastic support This is not desirable because it deforms the body.

〔Example〕

The present invention will be explained in more detail below using Examples and Comparative Examples. In the following Examples and Comparative Examples, all "parts" indicate "parts by weight."

Example-1 A magnetic coating liquid having the following composition was kneaded in a ball mill for 50 hours.

Fe alloy powder (15000e, BET surface area 50bo/
g, needle ratio 10/1) 400 parts Binder composition Resin with maleic acid added to a copolymer of allyl glycidyl ether and vinyl chloride (acid value 10, amount of unsaturated double bonds 2/molecule, number average Molecular weight 20,000) Urethane acrylate (acid value 1.8, number average molecular weight 10,000, average acryloyl group content 3 60 parts/molecule) 40 parts stearic acid 4 parts butyl stearate 4 parts A1□03
4 parts carbon black
10 parts medylethyl ketone
After dispersing 800 parts, it was coated on a polyethylene terephthalate support with a thickness of 10 μm using a doctor blade so that the dry film was 3 μm, and after orienting using a Konolt magnet, the solvent was dried (at 100°C for 1 minute). ) Post-calendering treatment was performed. Next, the tape was irradiated with an electron beam at an accelerating voltage of 165 KV and a beam current of 6 mA to give an absorbed dose of 7 Mrad, and then slit into 1/2 inch width to obtain video magnetic tape sample No. 1.

Magnetic tape samples were obtained in the same manner as in Example-1 except that the binder composition in Example-1 was changed as shown below. The evaluation results are summarized in Table 1.

Example-2... Sample No. A resin prepared by adding malonic acid and chloroacrylic acid to a copolymer of 2-allyl glycidyl ether and vinyl chloride (acid value 3, number average molecular weight 20,000, average acryloyl group content) Amount 3.4 pieces/molecule> 60 parts Urethane acrylate (acid value 3, number average molecular weight 10,000, average acryloyl group content 3 pieces/molecule) 40 parts Example-3...Sample N013 Butadiene monoxide and Resin made by adding citraconic acid to a vinyl chloride copolymer (acid value 10, number average molecular weight 15,000) 60 parts urethane acrylate (acid value 5, carbon-carbon unsaturated double bond content 2.7/molecule, Number average molecular weight 10,000, average acryloyl group content 5 pieces/molecule) 40 parts Example-4...Sample No. 4 Same vinyl chloride fruit resin as Example-1 6
0 parts Urethane acrylate (acid value 1.0, number average molecular weight 10,000, average acryloyl group content 3 pieces/molecule) 40 parts Example-5... Sample No. 5 Same vinyl chloride as Example-1 Fruit resin 60
40 parts of urethane acrylate (acid value: 100, number average molecular weight: 10,000, average content of acryloyl groups: 3 molecules, 7 molecules) Comparative Example-1: Sample No. 6: Same vinyl chloride fruit tree as Example-1: 60 parts Urethane acrylate (
Acid value O1 Number average molecular weight 10,000, average acryloyl group content 3 pieces/molecule) 40 parts Comparative example-2...Sample No. 7 Same PVC resin as Example-1 60 parts Urethane resin (acid value 3,
Thousands of average molecular weight 50,000, average acryloyl group content O/
molecule) 40 parts Comparative Example-3 Sample No. 8 Vinyl chloride, vinyl acetate copolymer Number average molecular weight 10,000 60 parts Urethane acrylate (acid value 3, number average molecule i 20,000, average acryloyl group content Comparative Example-4 Sample No. 9 Resin in which only malonic acid was added to a copolymer of allyl glycidyl ether and vinyl chloride (acid value 8, number average molecular weight 20,000) 60
40 parts of the same urethane acrylate as in Example-1 Comparative Example-5 Sample No. 60 parts of a resin prepared by adding only chloroacrylic acid to a copolymer of allyl glycidyl ether and vinyl chloride 60 parts 40 parts of the same urethane acrylate as in 1 (evaluation method) Measurement of acid value: 1 g of the material was dissolved in tetrahydrofuran and titrated with an ethyl alcohol-water (9515 V/Vχ) solution of potassium hydroxide using phenolphthalene as an indicator. The number of mg of potassium hydroxide was evaluated.

Still endurance time: Record a constant video signal on a videotape (each sample) using a VHS video tape recorder (manufactured by Matsushita Electric Industries (■), NV8200), and measure the time until the reproduced still image loses its clarity. (Experiments were conducted at 5°C and 80% RH).

Video S/N: Using the above video tape recorder,
Record the gray signal with 50% set-up and use Shibatsu 9
Measure the noise with a 25-inch S/N meter and check the sample no.
, expressed as a relative value when 1 is OdB.

Storage stability: After the magnetic coating liquid was stored for 24 hours at room temperature and stirred for 10 minutes, a magnetic tape was prepared by the method described in Example 1, and the video S/N was measured. Storage stability was evaluated using the video S/N of each sample when not stored as OdB.

Adhesion between support and magnetic layer Width: 1/2 inch, length: 5 cm
The adhesive force was defined as the force required for 180 degree peeling using sample tape.

Dynamic friction coefficient 2 Using the above video tape recorder, set the tape tension on the delivery side of the rotating cylinder to T11.
When the tape tension on the winding side is T2, the dynamic friction coefficient (μ) is defined by the following equation, and the running tension is evaluated using this μ.

T2 / T+ = e XP (μ*π) measurement is 40
°C165%RH Table 1 G [Effects of the Invention] As shown in Table 1, the magnetic layer of the magnetic recording medium of the present invention is made of an epoxy group-containing vinyl chloride copolymer with a polybasic unsaturated acid or an unsaturated acid. Containing as a binder one or more compounds from the group consisting of compounds obtained by adding saturated acids and polybasic acids, and polyurethane compounds containing C07H groups and carbon-carbon unsaturated bonds, and further irradiated with radiation. It can be seen that the magnetic recording medium characterized by this has excellent dispersibility of the ferromagnetic fine powder, exhibits good electromagnetic conversion characteristics, has a low coefficient of dynamic friction, and exhibits excellent still durability. Furthermore, in the method for manufacturing a magnetic recording medium of the present invention,
It was confirmed that the magnetic paint has excellent storage stability.

October 1, 1999 1 Temple and Month ° Nagakuden 1, Indication of the case Patent Application No. 93549 of 1988 2, Name of the invention Magnetic recording medium 3, Amendment 1 Relationship to the case: Patent applicant name: (520) Fuji Photo Film Co., Ltd. 4, Address: 14th floor 5, Toranomon Mitsui Building, 3-8-1 Kasumigaseki, Chiyoda-ku, Tokyo 100, Japan Date of the amended order: September 11, 1999 (Date of shipment:
(September 26, 1999) 6. Number of claims increased by amendment: 20 Agent: Patent Attorney (8107) Kiyoshi Sasaki 7;
Target of amendment: Specification (item “Detailed Description of the Invention”)
(3 others)

Claims (1)

[Claims] (1) A magnetic recording medium mainly consisting of a non-magnetic support and a magnetic layer, wherein the magnetic layer contains one or more compounds each of the groups shown in the following (A) and (B) as a binder, A magnetic recording medium characterized in that it is further irradiated with radiation. (A) A compound obtained by adding a polybasic unsaturated acid, or an unsaturated acid and a polybasic acid to an epoxy group-containing vinyl chloride copolymer. (B) A polyurethane compound containing a CO_2H group and a carbon-carbon unsaturated bond.