JPH0579698B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention relates to a vinylidene chloride/acrylonitrile-based polymer latex, and particularly to a polymer latex with excellent flame retardancy, light discoloration resistance, heat discoloration resistance, and film-forming properties. . More specifically, the polymer is made of the two specified resin components and is used as a material for flame-retardant binders and flame retardants for flame-retardant processing of industrial materials, compounds, films, films, sheets, flame-retardant paints, and processed products. It is related to latex. [Prior Art] Vinylidene chloride resin latex is known as a latex with excellent flame retardancy. The dry film of this latex is self-extinguishing, so it can be used for flame-retardant processing to pass flame-retardant regulations for various industrial materials such as fabrics, wallpapers, and foams.
It has been used as a flame retardant binder. In order for the dried film of the latex to exhibit sufficient flame retardant performance, it was necessary for the vinylidene chloride unit in the resin to exceed 60% by weight. However, there was a drawback of discoloration to yellowish brown, which is presumed to be caused by the polyene structure accompanying decomposition of the unit. In order to prevent discoloration, the content of this unit must be less than 40% by weight; otherwise, the oxygen index according to JIS K 7201 will be less than 23, and self-extinguishing properties will be lost. Therefore, vinylidene chloride-based resin latex containing 50 to 80% by weight of this unit has been used under the constraints of avoiding direct sunlight and high temperatures of 100°C or higher, but its poor light resistance and discoloration are particularly problematic under the conditions of use. The scope was extremely narrowed. The acrylonitrile unit itself as a component of vinylidene chloride resin latex is not new at all, and is disclosed in Japanese Patent Publication No. 13639/1983 and Japanese Patent Application Laid-open No. 115323/1983.
Numerous disclosures have been made in publications such as No. However, the invention disclosed in the publication discloses a latex for use in packaging materials, which is formed by forming a thin film on a plastic film to impart barrier properties.
Not only is the object different from that of the present invention, but also the structure of the present invention is different from the present invention in which the localized state of the acrylonitrile unit is specified as described later, and due to the significant discoloration, the field of application of the present invention is different. was not applicable at all. In addition, the technical idea of improving light discoloration resistance by dispersing particles with a high acrylonitrile content in agricultural and outdoor films such as polyvinyl chloride, and of using the particles as latex-like fine particles was disclosed in Japanese Patent Application Laid-Open No. 1983-1983. No. 19350, JP-A-59-
However, the purpose of these inventions is different from the purpose of the present invention, which is to provide a vinylidene chloride polymer latex for flame retardant use, and there are no application examples. Furthermore, the latex causes a decrease in heat discoloration resistance, whitening of the formed film, a decrease in colloid stability, and a decrease in resin solid content, so that the latex-like fine particles of the publication cannot be applied. On the other hand, as a composition containing vinylidene chloride/acrylonitrile units for the purpose of flame retardancy,
Flame retardant acrylic fibers are known. The fibers were produced by dissolving resin obtained by emulsion polymerization in an organic or inorganic solvent and spinning the resulting product. However, increasing the content of vinylidene chloride units not only significantly deteriorates both light and heat discoloration resistance, but also makes them poorly soluble in solvents. Currently, it has not been commercialized. Furthermore, the latex obtained by emulsion polymerization had poor film-forming properties due to its high glass transition point, and was completely unsuitable for practical use as a latex for flame retardant processing. As mentioned above, vinylidene chloride-acrylonitrile resin latex for imparting flame retardancy, vinylidene chloride-acrylonitrile-based resin latex for imparting barrier properties, and vinylidene chloride-acrylonitrile resin latex for flame-retardant fibers are well known. It is. However, none of the known latexes has a good balance of flame retardancy, light resistance, heat discoloration resistance, and film formability, and either they have problems and are subject to many restrictions in use, or they are not suitable for flame retardancy, which is the field of application of the present invention. It seemed that it could not be applied at all to processing binders, paints, etc. [Problem to be solved by the invention] In the field of binders and paints for flame retardant processing, color fastness, especially resistance to light discoloration, is important, so polymer latexes are used at the expense of flame retardant performance. Unavoidably, large amounts of expensive flame retardants are added, leading to increased costs, and problems such as decreased latex film strength and gloss.
A polymer latex with excellent flame retardancy, light and heat resistance, and film-forming properties has been desired. [Means and effects for solving the problem] The present inventors have conducted extensive studies in order to provide a polymer latex that satisfies both a high degree of flame retardancy, excellent light and heat discoloration resistance, and film formability. As a result of stacking, vinylidene chloride, which is made of two specified resin components, was
The present inventors have discovered that acrylonitrile polymer latex not only has outstanding flame retardancy, but also extremely excellent light and heat discoloration resistance and film-forming properties. That is, the present invention provides resin component (A) having the following composition: 65 to 95
% by weight and resin component (B) from 5 to 35% by weight, with a total vinylidene chloride unit content of 50 to 85% by weight, an acrylonitrile unit content of 4 to 25% by weight, and a vinyl monomer unit content of 7 to 40%. % by weight of a vinylidene chloride polymer latex. (A) Vinylidene chloride unit content 60-90% by weight, acrylonitrile unit content 8% by weight or less, vinyl monomer unit content 5-40% by weight, (B) Acrylonitrile unit content 30-70% by weight, vinylidene chloride unit Content 40% by weight or less, vinyl monomer unit content 10-50% by weight. The key points of the present invention are a resin component (A) containing vinylidene chloride structural units as a main component, and a resin component (B) containing 30 to 70% by weight of acrylonitrile units.
It is composed of two specified resin components. That is, a vinylidene chloride polymer latex having a molecular structure in which acrylonitrile units are localized exhibits excellent flame retardancy, light resistance, thermal discoloration resistance, and film formability. From the above-mentioned known techniques, it can be assumed that resin latexes containing units of vinylidene chloride, acrylonitrile, and vinyl monomers that are expected to have an effect on film-forming properties can be applied.However, resin latexes obtained by conventional techniques are The presence of vinylidene chloride and acrylonitrile units is completely different from that of the polymer latex of the present invention, and flame retardancy, light resistance, heat resistance, and film forming properties are not balanced, and in particular, light resistance is significantly inferior. The reason why the polymer latex of the present invention satisfies both high flame retardance and excellent light discoloration resistance is not clear, but it is presumed as follows. Oxygen index of polyacrylonitrile (JIS/K/
7201) 18, acrylonitrile units themselves do not have the effect of improving the flame retardancy of polymer latex, but when they coexist with vinylidene chloride units in the latex resin, they synergize the flame retardance of vinylidene chloride units. It is assumed that this will improve the results in a way that is close to the effectiveness. The present inventors set an upper limit on the acrylonitrile unit content for the resin component (A) with a vinylidene chloride unit content of 60% by weight or more, and set a large amount on the resin component (B) where the upper limit of the vinylidene chloride unit content is less than 40% by weight. By introducing acrylonitrile units,
As a total polymer latex, we were able to obtain a high degree of flame retardancy by incorporating a large amount of vinylidene chloride and acrylonitrile units without impairing the heat discoloration resistance of the dry film. Even more surprisingly, latex consisting of resin component (A) alone has a drawback in light discoloration resistance of the dry film due to the high content of vinylidene chloride units; however, when combined with resin component (B), The polymer latex of the present invention exhibits excellent light resistance to discoloration. This fact is due to the scattering of near-ultraviolet to ultraviolet light caused by the fact that the resin component (B), which has a moderately different refractive index from the resin component (A), is dispersed in units smaller than the average particle diameter of the polymer latex. It is assumed that Near-ultraviolet to ultraviolet light with high energy is scattered into the resin component (A).
This suggests that it may be difficult to reach. The resin component (B) may be introduced by the two-step polymerization method described below, or the polymer latex of the present invention may be obtained by blending latexes composed of each resin component (A) and (B). However, even if an acrylic ester latex with excellent light resistance is blended with a latex made of resin component (B), there will be no significant improvement in light resistance due to the dilution effect alone. Flame retardancy cannot be obtained either. The polymer latex described in the present invention is an aqueous dispersion of a copolymer resin with an average degree of polymerization of 100 or more obtained by emulsion polymerization, and can exist substantially stably at a resin solid content of 35% or more. say something The “resin latex” and “latex” used in the present invention are
Although it has the same meaning as "polymer latex," only the vinylidene chloride-based polymer latex of the present invention was distinguished by the term "polymer latex." The resin component (A) has a vinylidene chloride unit content of 60 to
90% by weight, acrylonitrile unit content 8% by weight
Below, the vinyl monomer unit content is 5 to 40% by weight. If the vinylidene chloride unit does not reach 60% by weight, the flame retardancy will be insufficient, and if it exceeds 90% by weight, the discoloration resistance will decrease due to the extreme localization of the vinylidene chloride unit.
In particular, it impairs light resistance to discoloration and significantly reduces film forming properties. Acrylonitrile units are preferable in terms of improving flame retardancy, but if they are contained in an amount exceeding 8% by weight, discoloration resistance, particularly heat discoloration resistance, will be significantly impaired. It is necessary to avoid having many acrylonitrile units adjacent to each other under a high vinylidene chloride unit content from the viewpoint of heat resistance and light discoloration resistance. The resin component (B) has an acrylonitrile unit content of 30
~70% by weight, vinylidene chloride unit content 40% by weight
Below, the vinyl monomer unit content is 10 to 50% by weight. If the acrylonitrile unit content does not reach 30% by weight, excellent light resistance to discoloration cannot be exhibited.
Even if it exceeds 70% by weight, the light discoloration resistance will not improve at all, and on the contrary, the heat discoloration resistance and film forming properties will be impaired, and the difference in refractive index with the resin component (A) will be too large and the film will turn white, making it impossible to put it into practical use. It disappears. Furthermore, the stability during emulsion polymerization and as a product latex is extremely reduced, making stable production impossible. The above-mentioned Japanese Patent Application Laid-open No. 59-124963 describes a method of improving the weather resistance of a water-based paint film by dispersing fine particles of acrylonitrile polymer with a particle size of less than 1 μm into a water-based paint whose main component is an acrylic acid ester. However, the acrylonitrile unit content of the acrylonitrile polymer fine particle dispersion in this publication is based on the description of low solid content and viscosity increase, as well as examples including related publications (Japanese Patent Laid-Open No. 106269/1983). clearly exceeds 70% by weight, which is not suitable for the purpose of the present invention. Vinylidene chloride units are preferable in terms of improving flame retardancy, but if they are contained in an amount exceeding 40% by weight, the discoloration resistance, particularly the light resistance, will be significantly impaired. The vinyl monomer unit is a vinyl monomer unit that can be copolymerized with vinylidene chloride and/or acrylonitrile, and includes (meth)acrylic acid alkyl esters such as methyl acrylate (or methacrylate), (meth)acrylic acid, etc. unsaturated carboxylic acids, hydroxyalkyl esters of unsaturated carboxylic acids such as hydroxyethyl (meth)acrylate, amide derivatives of unsaturated carboxylic acids such as (meth)acrylamide, unsaturated carboxylic acids such as N-methylol (meth)acrylamide, etc. N-alkylolamide derivatives of, esters of unsaturated carboxylic acids such as di(meth)acrylates and tri(meth)acrylates such as (mono, di, or tri) ethylene glycol di(meth)acrylate, and also methacrylonitrile. , styrene, vinyl chloride, divinylbenzene and the like. For the vinyl monomer unit, the following chlorine-containing or nitrogen-containing monomer components are preferred when cost performance or industrially usable monomer components are particularly required to have high flame retardancy. For example, vinyl monomers having a nitrogen content of 8% by weight or more, such as vinyl chloride, methacrylonitrile, acrylic amide, methacrylic amide, and N-phenylmaleimide, are preferred. Furthermore, 1-chloroacrylonitrile containing chlorine as well as an acid amide group or a nitrile group, and allyl cyanurate, a vinyl monomer having a melamine ring, can also be used. In addition, when film formability and yellowing resistance are required, methyl, ethyl, butyl,
2-ethylhexyl acrylate is preferred. Glycidyl (meth) as a vinyl monomer unit
It is preferable to introduce an oxirane oxygen-containing monomer such as acrylate or allyl glycidyl ether from the viewpoint of discoloration resistance, and especially in the resin component (B), the glass transition temperature of resins such as 2-ethylhexyl acrylate and butyl acrylate It is preferable to introduce a vinyl monomer that is extremely effective in reducing the viscosity. The polymer latex of the present invention has a resin component (A) of 60 to
95% by weight and resin component (B) 5 to 35% by weight, totaling 100% by weight. If the resin component (A) is less than 60% by weight (resin component (B) is more than 35% by weight), sufficient flame retardancy cannot be exhibited. Resin component (A) is 95% by weight
(Resin component (B) is less than 5% by weight)
and lacks color fastness, especially light fastness. In view of the balance between flame retardancy and discoloration resistance, the polymer latex of the present invention contains 70 to 90% by weight of resin component (A) and 10% by weight of resin component (B).
It is preferably composed of ~30% by weight, with a total of 50~85% by weight of vinylidene chloride units, 4~25% by weight of acrylonitrile units, and 7~7% by weight of vinyl monomer units.
More preferably, the content is 40% by weight. The following can be considered as a specific method for appropriately localizing each unit of vinylidene chloride and acrylonitrile by comprising two resin components (A) and (B). Two-step polymerization method: The first step is emulsion polymerization of the constituent monomer mixture of resin component (A), and the addition and emulsification of the constituent monomer mixture of resin component (B) in the presence of the latex produced in this step. A method of obtaining a desired polymer latex from a second step of polymerization. Latex bundling method: Two latexes each consisting of resin component (A) and resin component (B) are prepared separately by emulsion polymerization, and by blending these, the desired polymer is produced. How to get latex. In the two-step polymerization method, even if the second step polymerization is started either when the first step polymerization is completely completed or when unreacted monomers remain,
It is sufficient that the finally obtained polymer latex is composed of the two resin components (A) and (B) specified in the present invention. The latex particles obtained may be cap-polymerized to have a core/shell structure or a heterogeneous composition structure, or the two resin components may form separate particles. Furthermore, even if a seed polymerization recipe is used in which seed particles are formed in advance with a small amount of a monomer mixture, a small amount of monomer that is effective in lowering the glass transition point can be used as shown in JP-A-59-166517. Finally, the film-forming property may be improved by cap-polymerizing the mixture. In the polymer latex of the present invention prepared as described above, localization of resin components can be observed by electron microscopy, elemental analysis after solubility fractionation, infrared spectroscopy, NMR, etc. In order to further exhibit flame retardancy, light discoloration resistance, heat discoloration resistance, and film forming properties, various flame retardants, fillers, antiaging agents, plasticizers,
It is preferable to add a thickener or the like. It may be used in a blend with various resin latexes such as acrylic ester, ethylene/vinyl chloride, and styrene/butadiene. The flame retardance described in the present invention means that the polymer latex film itself has an oxygen index of 23 or higher and has excellent self-extinguishing properties, and has flame retardant properties that substantially impart flame retardancy to other materials. Say what you're doing. The polymer latex of the present invention can be used by itself as a flame-retardant binder, flame retardant, film, or sheet, or can be used as a base latex for a flame-retardant compound, or can be used as a flame-retardant paint by adding pigments, etc. It can be widely applied as processed products in the industrial materials field. [Example] The present invention will be explained in more detail with reference to Examples below, but it goes without saying that the present invention is not limited only to the Examples. Various preparation methods and evaluation methods in Examples,
The measurement method was as shown below. Polymer latex preparation method: Method: The pressure-resistant reactor of 3 was used. In the reactor, 95 parts by weight of water, 0.2 parts by weight of sodium persulfate,
Sodium alkyl diphenyl ether disulfonate (Sanyo Chemical, Eleminol MON-
2) 0.1 part by weight was added and the temperature was raised to 50°C. A total of 100 parts by weight of the monomer mixture was used.
Seed polymerization was carried out by adding 10% by weight of the predetermined parts by weight of the monomer mixture used in the first step into the reactor. Next, add 0.7 parts by weight of sodium alkyl diphenyl ether disulfonate.
After addition as a 25% aqueous solution, the remaining 90% by weight of the monomer mixture was continuously added quantitatively over 10 hours.
When the internal pressure decreased by 0.6 kg/cm ² from the highest pressure, a predetermined weight part of a monomer mixture for the second step having a composition different from that of the first step was added at once and polymerized. At the time when the reaction heat had almost disappeared, 0.04 parts by weight of sodium bisulfite was added as a 3% aqueous solution to complete the polymerization. The polymerization rate was over 99%. Method: A pressure-resistant reactor of No. 3 was used. 95 parts by weight of water, 0.15 parts by weight of sodium persulfate, and 0.1 parts by weight of sodium alkyl diphenyl ether disulfonate were charged into the reactor, and the temperature was raised to 50°C. A total of 100 parts by weight of the monomer mixture was used. Seed polymerization was carried out by adding 10% by weight of the monomer mixture all at once. Then sodium alkyl diphenyl ether disulfonate 0.7
After adding parts by weight as a 25% aqueous solution, the remaining 90% by weight of the monomer mixture was added all at once. At the time when the reaction heat had almost disappeared, 0.03 parts by weight of sodium bisulfite was added as a 3% aqueous solution to complete the polymerization. The polymerization rate was over 99%. Film-forming property evaluation method: A minimum film-forming temperature (MFT) measuring device with a temperature gradient on an aluminum flat plate was used. 20℃,
Polymer latex was coated on an aluminum flat plate in an atmosphere of 55% RH, and after standing to dry, the surface temperature of the low-temperature end of the transparent continuous film forming area of the polymer latex was measured and expressed as MFT (°C). It was determined that the lower the MFT, the better the film formability. Cast film preparation method: Polymer latex was cast on a flat glass plate set horizontally, and left standing in an atmosphere of 50℃ for 20 hours.
A film with a thickness of 350±15μ was prepared. Flame retardancy test method: Using a cast film of polymer latex, the oxygen index (LOI) was measured in accordance with JIS K 7201 (JIS D 1201). It was determined that the higher the oxygen index, the more flame retardant. Further, in Example 4, the following evaluation was added. Flame retardancy of mixed paper: Polymer latex containing 2 parts by weight of sodium alkyl diphenyl ether disulfonate per 100 parts by weight of resin solid content, wood pulp (NBKP), aluminum hydroxide (Showa Light Metal, Hygilite H- 31)
After fixing with an aluminum sulfate aqueous solution, papermaking and drying were carried out to produce mixed paper with a basis weight of 150 g/m ² and a paper composition of pulp/aluminum hydroxide/polymer latex resin content = 29/59/12 (weight ratio). Obtained. Width 15mm length 200mm from the mixed paper
A liquefied petroleum gas burner (JIS K 7201, diameter 3 mm) with a flame length of 1 inch was prepared.
The flame was repeatedly applied to the top for 0.5 seconds and the flame released for 0.5 seconds until the test piece, which was held vertically, burst into flame. The number of times of flame contact until the paper continues to burn without self-extinguishing even after flame retardation is displayed. Indicates that Flame retardancy of compound coated fabric: Polymer latex containing 3 parts by weight of polyoxyethylene nonyl phenol ether (Kao, Emulgen 920) per 100 parts by weight of resin solids and aluminum hydroxide (Showa Light Metal, Hygilite H- 42) and alkali thickener (Japan Acrylic Primal ASE-
60) to thicken the polymer latex resin/aluminum hydroxide = 60/40 (weight ratio)
compound was obtained. The compound is made of nylon plain weave fabric (basis weight 300g/
m ² ) Apply dry weight 90g/m ² to the back surface using Warner Matisse "Coating device LFT/SV type" (doctor knife method) and dry, JIS, D,
The burning rate was measured in accordance with 1201 (MVSS-302). The flame came into contact with the fabric surface, and among those exhibiting self-extinguishing properties, those that extinguished before reaching marked line A were designated as NB, and the flame retardant performance of the polymer latex was judged to be particularly excellent. Method for evaluating light resistance to discoloration: A cast film of polymer latex was fixed on blackboard paper, and irradiated with ultraviolet rays for 100 hours at a black panel temperature of 63°C using Suga Test Instruments "Ultraviolet Long Life Fade Meter FAL-3H." After irradiation, the cast film has yellowness,
Color fastness was determined based on whiteness. Heat discoloration resistance evaluation method: Polymer latex cast film was heated at 150°C using Sanei Seisakusho's Dalton Gear Oven.
Heat treatment was performed at ℃ for 3 hours. The cast film after the treatment turned dark and discolored, so heat resistance to discoloration was determined based on whiteness. Yellowness measurement method: In accordance with JIS K 7103, the yellowness of the cast film was measured by the reflection method using Suga Test Instruments "Color Computer SM-4-CH". The formula for calculating the degree of yellowness is as follows, and the smaller the value of the degree of yellowness, the better the color fastness. YI=100(1.28X-1.06Z)/Y YI: Yellowness X, Y, Z: 3 of test sample in standard light C
Stimulus value Whiteness measurement method: Suga Test Instruments “Color Computer SM-4-”
The whiteness of the cast film was measured by a reflection method using "CH". The whiteness was calculated using the Hunter method as follows. The larger the whiteness value, the better the color fastness. W=100−[(100−L) ² +a ² +b ² ) ^1/2 W: Whiteness L: 10Y ^1/2 a=17.5(1.02X−Y)/Y ^1/2 b=7.0(Y−0.847 Z)/Y ^1/2 X, Y, Z: 3 of the test sample in standard light C
Stimulus value Electron microscopy observation method: Polymer latex cast film is exposed to copper sulfate/hydroxylamine sulfate aqueous solution (approximately 90℃)
It was immersed in dyeing and dried. The cast film was freeze-cut using a microtome to prepare microscopic sections. Accelerating voltage using Hitachi “H500”
Observation was made using the transmission method at 100KV. In this method, AN
The units are stained and show a strong contrast. Method for calculating the content of each monomer unit: The content of each monomer in the tables of Examples was expressed according to the following rules. "Monomer charge composition" indicates the number of parts by weight of each monomer used during polymerization (total 100 parts by weight). "Polymer latex composition" refers to the measured value of each monomer unit content in the final form of the polymer latex used for evaluation, regardless of whether it is a one-step polymerization latex, a two-step polymerization latex, or a bundled latex. The calculated value was written after confirming that it was the same as the calculated value from . To measure the content of each monomer unit in polymer latex,
It was carried out by the following method using a salted-out dry resin, and if the difference from the calculated value was within ±1%, it was considered to be the same. Vinylidene chloride unit content: Determined from the amount of chlorine measured by Schoeniger's oxygen flask method. Acrylonitrile unit content: Determined from the amount of nitrogen measured by the Micro Kjeldahl method. In addition, each monomer or each monomer unit in the table of Examples is indicated by the following abbreviations. VDC: Vinylidene chloride AN: Acrylonitrile MA: Methyl acrylate BA: n-butyl acrylate 2EHA: 2-ethylhexyl acrylate HEA: 2-hydroxyethyl acrylate Example 1 First step monomer amount using the monomer charging composition shown in Table 1 Polymer latex A consisting of 80 parts by weight of monomer and 20 parts by weight of second step monomer was obtained by the method (second step polymerization method). For comparison, latex C having the same composition as polymer latex A was obtained using a method from a single monomer mixture. Furthermore, the first and second polymer latex A
Latexes D and E having the compositions of each step were prepared by each method, and a polymeric latex B was prepared by blending them at a dry resin weight ratio of latex D/latex E: 80/20. These latexes were evaluated for flame retardancy, resistance to light and heat discoloration, and film formability. Electron micrographs were taken of the cast films of Latex A, B, and C. Example 2 Each monomer was prepared using a method (two-step polymerization method) with the monomer charge composition shown in Table 2, the first step monomer being 85 parts by weight, and the second step monomer being 15 parts by weight. Latexes F to K and U to X were prepared and evaluated for flame retardancy, light resistance, heat resistance, and film formability. Example 3 2, each prepared by the method as shown in Table 3.
Latexes L to P were prepared by blending the seed latexes at various ratios, and their flame retardance, light resistance, heat resistance, and film forming properties were evaluated. Example 4 Polymer latex Q consisting of 85 parts by weight of the first step monomer and 15 parts by weight of the second step monomer with the monomer composition shown in Table 4 was prepared by the method (two-step polymerization method). Obtained. For comparison, latex R having the same composition as polymer latex Q, latex S having the same vinylidene chloride unit content, and latex T having the same level of light resistance to discoloration were each obtained by a method from a single monomer mixture. . These prepared latexes were evaluated for flame retardancy, light resistance, heat resistance, film forming properties, and flame retardancy of mixed paper and compound-coated fabric. The results of Example 1 are shown in Table 1. The polymer latexes A and B of the present invention have high flame retardancy, excellent light resistance and
Both heat discoloration resistance and film formability were satisfied. Latex C, which does not have two types of resin components, changed color to yellowish brown in a light discoloration test and was determined to be unusable for practical use, and it was also thought that there were problems with film-forming properties at room temperature in winter. Electron micrographs of cast films of latexes A, B, and C are shown in FIGS. 1, 2, and 3, respectively. It can be seen that in the films formed from the polymer latexes A and B of the present invention, acrylonitrile units are appropriately localized. In Latex C, acrylonitrile units are uniformly dispersed over the entire surface of the film, and due to the drift of the monomer composition in the latter half of polymerization, non-film-forming particles are formed, which are presumed to be formed from monomers mainly consisting of vinylidene chloride and not containing acrylonitrile. Observed (less than 20% by weight of the total). The results of Example 2 are shown in Table 2. While the polymer latexes F and J of the present invention exhibited excellent flame retardancy, light resistance and heat discoloration resistance, and film forming properties, the composition of resin component (A) or (B) was within the scope of the present invention. It was determined that unspecified latexes had extremely low light resistance, heat resistance to color change, film formability, and flame retardancy, and could not be put to practical use. Also, since Latex H gelled during polymerization due to the high acrylonitrile content in the second step, the amount of polymerization water was adjusted so that the resin solid content after polymerization was 25% to obtain a latex. The results of Example 3 are shown in Table 3. While the polymer latex L of the present invention showed excellent flame retardancy, light resistance, heat discoloration resistance, and film forming properties, the composition or blending ratio of the resin component (A) was not specified within the scope of the present invention. It was determined that the latex had extremely low flame retardancy, light resistance/thermal discoloration resistance, and film formability, making it unusable for practical use. The results of Example 4 are shown in Table 4. The polymer latex Q of the present invention exhibited excellent flame retardancy, light resistance, thermal discoloration resistance, and film forming properties, and processed products thereof also exhibited excellent flame retardancy. Latex R that does not have two resin components
Although it has excellent flame retardancy, its light resistance and heat resistance to discoloration are extremely poor, and the processed product was judged to be unsuitable for practical use. Latex S, obtained by removing the acrylonitrile component from Latex R, not only had insufficient light discoloration resistance but also had lower flame retardancy. In the latex T prepared so that the light discoloration resistance was comparable to that of the polymer latex of the present invention, the cast film of the latex itself had some self-extinguishing properties, but the processed product of this example was made flame retardant. I couldn't do that.

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〔Effect of the invention〕

The effects of the present invention are summarized as follows. (1) A polymer latex that satisfies high flame retardancy, excellent light and heat discoloration resistance, and film-forming properties. (2) It is a versatile polymer latex that can be used both indoors and outdoors. (3) It is a polymer latex with great cost advantages as it can reduce the need for expensive flame retardants and additives. (4) It is a high-quality polymer latex that can be used alone as a flame-retardant binder, flame retardant, flame-retardant film, or flame-retardant sheet. (5) It is a polymer latex that can be applied to a wide range of industrial materials such as flame retardant compounds, flame retardant paints, and processed products coated with these compounds and paints.

[Brief explanation of the drawing]

Figures 1A and B are electron micrographs showing the cross section of a cast film of polymer latex A of the present invention (Example 1), and Figures 2A and B are of the present invention (Example 2).
FIGS. 3A and 3B are electron micrographs showing a cross section of a cast film of latex C as a comparative example, which is not of the present invention. however,
In both cases, A has a magnification of 44,000 and B has a magnification of 15,600.

Claims (1)

[Scope of Claims] 1 Consists of 65 to 95% by weight of resin component (A) and 5 to 35% by weight of resin component (B) of the following composition, with a total vinylidene chloride unit content of 50 to 85% by weight and acrylonitrile unit content 4 to 25% by weight, and a vinylidene chloride polymer latex having a vinyl monomer unit content of 7 to 40% by weight. (A) Vinylidene chloride unit content 60-90% by weight, acrylonitrile unit content 8% by weight or less, vinyl monomer unit content 5-40% by weight, (B) Acrylonitrile unit content 30-70% by weight, vinylidene chloride unit Content, 40% by weight or less, vinyl monomer unit content 10-50% by weight. 2. In the presence of a vinylidene chloride resin latex consisting of 65 to 95 parts by weight of resin component (A) in terms of dry resin content, a monomer mixture of 5 to 35 parts by weight of resin component (B) is added.
The vinylidene chloride polymer latex according to claim 1, which is obtained by addition polymerization of parts by weight.