JP2000169657A - Emulsion for flame-retarded foam sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an emulsion for flame-retarded foam sheets that has the excellent flame retardancy that is friendly to the global environment and the work environment without emission of hazardous chlorine gas on incineration, given foamed product having excellent mechanical strengths, resistance to water, alkali, blocking and cracking and shows good embossing processability, when it is embossed. SOLUTION: In the presence of an emulsion comprising a vinyl alcohol polymer as a dispersant and a polymer from vinyl ester monomer as a dispersoid, (meth)acrylic ester monomer is emulsion-polymerized to give the objective emulsion that comprises (A) a polymer from vinyl ester monomer and (B) a polymer from (meth)acrylic ester monomer at a weight ratio (A)/(B) of 70/30-20/80 where the glass transition temperature of the component (A) is -15 to 30 deg.C, while that of the component (B) is -15 to 20 deg.C.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to an emulsion for a flame-retardant foam sheet, an emulsion composition for a flame-retardant foam sheet, and a flame-retardant foam sheet obtained from the emulsion composition for a flame-retardant foam sheet.

[0002]

2. Description of the Related Art Conventionally, emulsions containing a copolymer containing vinyl chloride as a polymer component have been used for wallpaper.
It was used as an emulsion for flame-retardant foam sheets. However, wallpaper using a copolymer containing vinyl chloride generates harmful chlorine gas and dioxin during incineration and has problems from the viewpoint of the global environment and work environment. An emulsion for a flammable foam sheet is desired.

[0003]

DISCLOSURE OF THE INVENTION The present invention solves the above-mentioned problems in the prior art, is environmentally friendly, has excellent flame retardancy, and further has mechanical strength, crack resistance, water resistance, alkali resistance, and blocking resistance. An object of the present invention is to provide an emulsion, a composition, and a flame-retardant foam sheet for a flame-retardant foam sheet which are excellent in foaming properties, and which are excellent in embossing properties when embossing.

[0004]

An object of the present invention is to provide a method for preparing a (meth) acrylic acid ester in the presence of an emulsion in which a vinyl alcohol polymer is used as a dispersant and a polymer comprising a vinyl ester monomer is used as a dispersoid. (A) consisting of a vinyl ester monomer obtained by emulsion polymerization of a monomer
Weight ratio of (A) / (B) = 70/30 to 20 (A) / (B)
/ 80, and the glass transition temperature of the component (A) is -1.
5 ° C to 30 ° C, glass transition temperature of component (B) is -15 ° C
Emulsion (C) for flame-retardant foamed sheet at -20 ° C
Is achieved by providing The above purpose is
Emulsion (C), thermally expandable hollow microsphere (D)
And an inorganic filler (E) having a solid content of 10
(D) 5 to 50 parts by weight, (E) 50 to 3 parts per 0 parts by weight
By providing an emulsion composition for a flame-retardant foam sheet which is 00 parts by weight, and further by applying the composition on a substrate, drying and heating and foaming to provide a flame-retardant foam sheet. Achieved.

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION

The vinyl ester monomers used in the first emulsion constituting the component (A) of the emulsion of the present invention include vinyl formate, vinyl acetate, vinyl propionate, vinyl versatate, vinyl pivalate and the like. And vinyl esters. Preferably,
Vinyl acetate alone or a combination of vinyl acetate and other vinyl esters. As the copolymerizable ethylenically unsaturated monomer, various types can be used, and specific examples of the ethylenically unsaturated monomer include ethylene, propylene, olefins such as isobutylene, acrylic acid, and methacrylic acid. Acids, acrylates such as methyl acrylate, ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, dodecyl acrylate, 2-hydroxyethyl acrylate, methyl methacrylate, ethyl methacrylate, butyl methacrylate, methacrylic acid 2-ethylhexyl, dodecyl methacrylate, methacrylic acid 2
-Hydroxyethyl and the like. Preferred examples include olefins such as ethylene, propylene, and isobutylene, with ethylene being more preferred.

[0007] The component (A) of the emulsion of the present invention is composed of 0 to 30% by weight of ethylene and 100% of a vinyl ester monomer.
-70% by weight of a vinyl ester-based emulsion, more preferably 5-30% by weight of ethylene and 95-70% by weight of an ethylene-vinyl ester copolymer emulsion comprising a vinyl ester-based monomer. The content of ethylene is preferably 5 to 30% by weight, more preferably 7 to 27% by weight, and particularly preferably 10 to 25% by weight. If the ethylene content is low, the emulsion may be poor in alkali resistance when blended for a flame-retardant foam sheet. When the ethylene content is more than 30% by weight, the mechanical strength and the blocking resistance are inferior and may not be preferable. The content of the vinyl ester monomer is preferably 95 to 70% by weight, more preferably 93 to 73% by weight, and particularly preferably 90 to 75% by weight. If the content is less than 75% by weight, the mechanical strength and the blocking resistance are inferior.
The glass transition temperature of the component (A) is preferably from -15C to 30C, more preferably from -15C to 25C.

The (meth) acrylate monomers used in the emulsion constituting the component (B) of the emulsion of the present invention include methyl acrylate, ethyl acrylate, n-propyl acrylate and i-acrylate acrylate. Propyl, n-butyl acrylate, i-butyl acrylate,
Acrylic esters such as t-butyl acrylate, 2-ethylhexyl acrylate, dodecyl acrylate, octadecyl acrylate, hydroxyethyl acrylate, hydroxypropyl acrylate, hydroxybutyl acrylate, methyl methacrylate, ethyl methacrylate, methacryl N-propyl acid, i-propyl methacrylate,
Methacrylic acid such as n-butyl methacrylate, i-butyl methacrylate, t-butyl methacrylate, 2-ethylhexyl methacrylate, dodecyl methacrylate, octadecyl methacrylate, hydroxyethyl methacrylate, hydroxypropyl methacrylate, hydroxybutyl methacrylate, etc. Esters and the like.

These may be used singly or as a mixture of two or more. The glass transition temperature of the polymer (B) comprising the monomer is from -15 ° C to 20 ° C. ° C
-15 ° C to 15 ° C is more preferable. When the glass transition temperature is lower than −20 ° C., the blocking resistance is poor, and when the glass transition temperature exceeds 20 ° C., the crack resistance is poor.

In the emulsion of the present invention, the weight ratio of the polymer (A) to the polymer (B) is (A) / (B) = 70/30.
It is important that it is ２０20/80. When the weight ratio is within this range, crack resistance, water resistance and durability can be improved.

The content of the (meth) acrylate constituting the component (B) is such that the weight ratio of the polymer (A) to the polymer (B) is (A) / (B) = 70/30 to 20 / 80, preferably 70/30 to 30/70. If the content is excessive, the blocking resistance is poor. On the other hand, when it is too small, the embossing property is inferior.

Further, the emulsion (C) of the present invention may contain a functional vinyl monomer in the range of 10% by weight or less. By containing this, it is possible to improve the dispersibility of the inorganic filler, improve the stability of the composition, and further improve the crack resistance and the blocking resistance.

Examples of the functional vinyl monomer include carboxyl group-containing monomers such as acrylic acid, methacrylic acid, crotonic acid, itaconic acid and maleic acid, and acrylamide, methacrylamide, N-methylolacrylamide, N, N-dimethylacrylamide, Amide group-containing monomers such as acrylamide of acrylamide-2-methylpropanesulfonic acid and its sodium salt, amino group-containing monomers, hydroxy group-containing monomers such as mono (meth) acrylate of polyhydric alcohol and monoallyl ether of polyhydric alcohol, Examples include epoxy group-containing monomers such as glycidyl (meth) acrylate, and sulfone group-containing monomers such as sodium methacrylsulfonate.

The emulsion (C) of the present invention may contain a copolymerizable crosslinking monomer having two or more polymerizable double bonds. Examples of the monomer having two or more polymerizable double bonds include ethylene glycol diacrylate, triallyl cyanurate, diallyl phthalate, allyl methacrylate, triallyl isocyanurate, and adipic diacrylate. Content is 3
% By weight or less is preferred.

The emulsion (C) of the present invention uses a vinyl alcohol-based polymer as a dispersant, and in the presence of an emulsion containing a vinyl ester-based monomer as a dispersoid,
It is obtained by emulsion polymerization of a (meth) acrylate monomer. The average degree of polymerization of the vinyl alcohol polymer as a dispersant is 200 to 4000, preferably 300 to 2600, and the degree of saponification is 70 to 100 mol%, preferably 75 to 99 mol%. Also, modified polyvinyl alcohol by a known technique such as copolymerization, post-reaction, and terminal modification can be used. By using such an emulsion (C) of the present invention, a flame-retardant foam sheet excellent in water resistance, alkali resistance, mechanical strength and the like can be obtained. In the emulsion polymerization of (meth) acrylic ester-based monomers, it is common to use an emulsifier as a dispersant, but a vinyl alcohol-based polymer is used as a dispersant,
When emulsion polymerization of a (meth) acrylate monomer is carried out in the presence of an emulsion containing a vinyl ester monomer as a dispersoid, it is used as a second stage dispersant and a first stage dispersant. It is possible to use a vinyl alcohol-based polymer obtained.

As a method for producing the emulsion (C) for a flame-retardant foamed sheet of the present invention by emulsion polymerization, a conventionally known emulsion polymerization method can be used. For example, the monomers constituting the polymer (A) are added at once or sequentially in the presence of the aqueous dispersant solution and the initiator to carry out polymerization, and then the monomers constituting the polymer (B) are added at once. Alternatively, a two-stage emulsion polymerization method in which emulsion polymerization is carried out intermittently or continuously by adding to the polymerization system, or a monomer constituting the polymer (A) or the polymer (B) is previously added to an aqueous dispersant solution. A method of sequentially adding the emulsified emulsion to the emulsion polymerization system is used as a suitable method. It is also possible to add an organic solvent such as various alcohols and alkanes and a chain transfer agent such as dodecyl mercaptan to the emulsion polymerization system as long as the performance of the flame-retardant foam sheet emulsion is not impaired.

In the emulsion polymerization of the emulsion (C) for a flame-retardant foamed sheet of the present invention, as the initiator, conventionally known initiators such as persulfate, hydrogen peroxide, tertiary butyl hydroperoxide and the like can be used. A water-soluble initiator, various azo-based initiators, and various peroxide-based initiators are used alone or in a redox system in combination with a reducing agent such as tartaric acid, L-ascorbic acid, Rongalit, and ferrous ion. Further, as a method of adding the initiator, usually, any of batch addition, intermittent addition, and continuous addition is used. It is preferable that the minimum film-forming temperature of the emulsion (C) thus obtained is 30 ° C. or lower in terms of cracking, water resistance and durability. Furthermore, the preferred minimum film forming temperature is
25 ° C. or less. Here, the minimum film forming temperature is a value measured by a thermal gradient test device.

The emulsion (C) for a flame-retardant foamed sheet of the present invention is blended with the heat-expandable hollow fine particles (D) and the inorganic filler (E) to obtain a suitable emulsion for a flame-retardant foamed sheet. A composition is obtained. This composition contains the components (C), (D) and (E), and the content of (D) is 5 to 50 parts by weight per 100 parts by weight of the solid content of (C). The amount is 50 to 300 parts by weight per 100 parts by weight of the solid content of (C).

The heat-expandable hollow microspheres (D) used in the present invention are foaming agents comprising microspheres which can be expanded and foamed by heating, for example, polyvinylidene chloride, a copolymer of vinylidene chloride and acrylonitrile. ,
Polyacrylonitrile, ethane inside a shell part composed of a copolymer of acrylonitrile and methyl acrylate,
It is a sphere having a particle size of 1 to 50 μ containing a low boiling point hydrocarbon such as propane, butane, heptane and the like. As the component (D), a commercial product (trade name “Microsphere” manufactured by Matsumoto Yushi Co., Ltd.) can be mentioned as a typical example. By blending the component (D) with the component (C), it is possible to obtain a flame-retardant foam sheet having excellent foaming properties and little deterioration in mechanical strength and the like.

Examples of the inorganic filler (E) constituting the emulsion composition for a flame-retardant foam sheet of the present invention include aluminum hydroxide, magnesium hydroxide, barium hydroxide, calcium carbonate, magnesium carbonate, calcium sulfate, and sulfuric acid. Examples include barium, silica sand, clay, talc, silicas, titanium dioxide, magnesium silicate, ferrous hydroxide, basic zinc carbonate, basic lead carbonate and the like.
Preferred are aluminum hydroxide, calcium carbonate, magnesium hydroxide, basic zinc carbonate, basic lead carbonate and the like. By blending the component (E), a flame-retardant sheet excellent in flame retardancy and excellent in foaming property, mechanical strength and crack resistance can be obtained.

The mixing ratio of the components (C), (D) and (E) in the present invention is as follows. The content of the component (D) is 5 to 50 parts by weight, preferably 10 to 40 parts by weight, per 100 parts by weight of the solid content of the component (C). When the amount of the component (D) is less than 5 parts by weight, the foaming property is poor. The content of the component (E) is 100% of the solid content of the component (C).
50 to 300 parts by weight per part by weight, preferably 100 to 300 parts by weight
250 parts by weight. When the amount of the component (E) is less than 50 parts by weight, the flame retardancy is poor. On the other hand, when the amount of the component (E) exceeds 250 parts by weight, the foaming properties, mechanical strength and crack resistance are poor.

Next, the flame-retardant foam sheet of the present invention will be described. The flame-retardant foamed sheet of the present invention is obtained by applying the above-described emulsion composition for a flame-retardant foamed sheet composed of (C), (D) and (E) onto a substrate, followed by drying and heating and foaming. Can be manufactured. Examples of the substrate include paper and cloth. Application of the composition to the substrate is a roll coater, a reverse roll coater, a coating method such as a doctor coater and screen printing, gravure printing,
A known method such as a concavo-convex printing method such as engraving roll printing or flexographic printing can be employed. Then, after drying, foaming treatment, embossing, and the like can be performed.

The flame-retardant foamed sheet thus obtained is suitably used as wallpaper. Other uses include
Used for wall coverings, decorative sheets, etc.

[0024]

The present invention will be described more specifically below with reference to examples and comparative examples. In Examples and Comparative Examples, “parts” and “%” are based on weight unless otherwise specified.

Example 1 4 parts of polyvinyl alcohol (polymerization degree: 500, saponification degree: 88.3 mol%) and 100 parts of ion-exchanged water were put into a glass polymerization vessel equipped with a stirrer, a nitrogen inlet, and a thermometer and dissolved by heating. After cooling, the pH was adjusted to 4.0 with sulfuric acid, and then transferred to a stainless steel polymerization vessel. After adding 40 parts of vinyl acetate and performing nitrogen bubbling, the temperature was raised to 60 ° C., 35 kg / cm ^{2 of} ethylene was added, 30 ml of a 2% aqueous Rongalite solution was added, and 0.4% aqueous hydrogen peroxide was successively added. To start the first stage polymerization. 30 minutes after the start of the polymerization, the sequential addition of an acrylic monomer (a mixture of 60 parts of methyl methacrylate, 40 parts of 2-ethylhexyl acrylate, and 4 parts of hydroxyethyl acrylate) was started, and the polymerization of the second-stage acrylic portion was started. did. Furthermore, the sequential addition of the post-addition dispersant (20 parts of a 10% aqueous solution of polyvinyl alcohol having a degree of polymerization of 300 and a saponification degree of 88.1 mol%) was started. Acrylic monomer added sequentially and stabilizer added after 2
Added uniformly over time. One hour after the end of the sequential addition, the polymerization was terminated, and ethylene-containing 15 wt% ethylene-
A two-stage polymerization emulsion (C) containing a vinyl acetate copolymer (A) and an acrylic polymer (B) and having a solid content of 50.1% was obtained. After adding 40 parts of water to 100 parts of the solid content of this emulsion, 20 parts of thermally expandable hollow microspheres ("Microsphere" manufactured by Matsumoto Yushi Co., Ltd.) and 150 parts of aluminum hydroxide are added to form a flame-retardant foam sheet. The composition was prepared. Using this, a test was performed under the following conditions.
The results are shown in Tables 1 and 2. [Test conditions] 1. Preparation of Foam Sheet The composition was applied to release paper so that the thickness after drying was 0.2 mm, dried at 100 ° C. for 10 minutes, and further dried at 180 ° C.
The foamed sheet was obtained by heating at 1 ° C. for 1 minute to foam. 2. Foaming ratio Foaming ratio = (thickness of sheet after heating at 180 ° C. for 1 minute / 100 ° C., thickness of sheet after drying for 10 minutes) was evaluated. 3. Water resistance The foamed sheet is immersed in water at 20 ° C. for 24 hours, and the appearance thereof is observed. evaluated. 4. Alkali resistance The foamed sheet is immersed in a 1N aqueous solution of sodium hydroxide at 20 ° C. for 24 hours, and the appearance is observed. (With dissolution). 5. Blocking resistance The application surfaces of the foamed sheets are overlapped with each other, 45 ° C, 90%
Under a condition of RH (relative humidity), a load of 5 kg / cm ² was applied and left for 24 hours. Thereafter, the coated surfaces of the foam sheet were peeled off by hand, and evaluated based on the criteria of ○ (no resistance), Δ (with resistance), and × (breakage of material). 6. Crack resistance The foamed sheet was bent at 180 degrees, and the appearance of the bent portion was observed. ○ (no abnormality), Δ (partially cracked) and ×
The evaluation was based on the criteria of (there was a crack on the entire surface). 7. Mechanical strength Rub the coated surface of the foam sheet with a finger, observe the appearance,
(No abnormality), Δ (partly scratched) and × (surface peeling of coating film) were evaluated. 8. Embossability After embossing the foamed sheet with an embossing roll (150 ° C.), the unevenness of the sheet surface is visually observed and evaluated as follows.
The evaluation was made based on the criterion of × (uneven pattern is unclear). 9. Flame retardancy A foam sheet having a length of 300 mm and a width of 30 mm was suspended vertically, and was blown for 5 seconds from below with a gas burner, and the burning distance (burning speed) per minute was measured.

Example 2 4 parts of polyvinyl alcohol (polymerization degree: 500, saponification degree: 88.3 mol%) and 100 parts of ion-exchanged water were put into a glass polymerization vessel equipped with a stirrer, a nitrogen inlet, and a thermometer and dissolved by heating. After cooling, the pH was adjusted to 4.0 with sulfuric acid, and then transferred to a stainless steel polymerization vessel. After adding 79 parts of vinyl acetate and performing nitrogen bubbling, the temperature was raised to 60 ° C., 15 kg / cm ^{2 of} ethylene was added, 30 ml of a 2% aqueous Rongalite solution was added, and 0.4% hydrogen peroxide was successively added. To start the first stage polymerization. Thirty minutes after the start of the polymerization, the sequential addition of an acrylic monomer (a mixture of 30 parts of methyl methacrylate and 37 parts of 2-ethylhexyl acrylate) was started, and the polymerization of the second-stage acrylic portion was started. Further, a post-added stabilizer (polymerization degree 300, saponification degree 8
8.1 mol% polyvinyl alcohol 10% aqueous solution 2
0 parts). The sequentially added acrylic monomer and post-added stabilizer were added uniformly over 2 hours.
One hour after the end of the sequential addition, the polymerization was completed and the ethylene content was 6
A two-stage polymerization emulsion (C) containing 5% by weight of a solid content containing an ethylene-vinyl acetate copolymer (A) and an acrylic polymer (B) in wt% was obtained. After adding 40 parts of water to 100 parts of the solid content of this emulsion, 20 parts of thermally expandable hollow microspheres ("Microsphere" manufactured by Matsumoto Yushi Co., Ltd.) and 150 parts of aluminum hydroxide are added to form a flame-retardant foam sheet. The composition was prepared. Using this, a test was performed under the following conditions. The results are shown in Tables 1 and 2.

Example 3 Polymerization was carried out in the same manner as in Example 1 except that vinyl acetate was 42 parts, ethylene pressure was 25 kg / cm 2, and hydroxyethyl methacrylate was used instead of hydroxyethyl acrylate. As a result, an emulsion having an ethylene content of 12% by weight and a solid content of 50.0% was obtained. Using this emulsion, a composition was prepared and evaluated in the same manner as in Example 1. The results are shown in Tables 1 and 2.

Example 4 Example 1 was repeated, except that hydroxyethyl acrylate was not used. Table 1 shows the results
~ 2.

Example 5 Example 2 was repeated except that vinyl acetate was 40.3 parts, ethylene pressure was 45 kg / cm ² , 65 parts of methyl methacrylate and 35 parts of 2-ethylhexyl acrylate were used. Polymerization was carried out in the same manner to obtain an emulsion having an ethylene content of 15% by weight and a solid content of 49.9%.
Using this emulsion, a composition was prepared and evaluated in the same manner as in Example 1. The results are shown in Tables 1 and 2.

Example 6 4 parts of polyvinyl alcohol (polymerization degree: 500, saponification degree: 88.3 mol%) and 100 parts of ion-exchanged water were put into a glass polymerization vessel equipped with a stirrer, a nitrogen inlet, and a thermometer and dissolved by heating. did. After cooling, the pH was adjusted to 4.0 with sulfuric acid, and the temperature was raised to 70 ° C. while performing nitrogen bubbling.
With stirring at 150 rpm, 84 parts of vinyl acetate were added,
Further, 30 parts of a 2% Rongalite aqueous solution was added, and the mixture was added to 0.1%.
The first stage polymerization was started by sequentially adding 4% aqueous hydrogen peroxide. One hour after the start of the polymerization, an acrylic monomer (40 parts of methyl methacrylate, 2-ethylhexyl acrylate 27)
Part) was added dropwise to initiate second stage polymerization. Furthermore, the sequential addition of the post-addition dispersant (20 parts of a 10% aqueous solution of polyvinyl alcohol having a degree of polymerization of 300 and a saponification degree of 88.1 mol%) was started. The sequentially added acrylic monomer and post-added stabilizer were added uniformly over 2 hours. 1 after the end of sequential addition
The polymerization was completed in a time, and a two-stage polymerization emulsion (C) containing a polyvinyl acetate polymer (A) and an acrylic polymer (B) and having a solid content concentration of 50.1% was obtained. Using the obtained emulsion, a composition was prepared and evaluated in the same manner as in Example 1. The results are shown in Tables 1 and 2.

Example 7 Using an emulsion polymerized in the same manner as in Example 1, 40 parts of water was added to 100 parts of the solid content of the emulsion, and then 10 parts of thermally expandable hollow fine particles and 200 parts of aluminum hydroxide were added. Thus, a composition for a flame-retardant foam sheet was prepared. This composition was evaluated in the same manner as in Example 1. The results are shown in Tables 1 and 2.

Example 8 Using an emulsion polymerized in the same manner as in Example 1, 40 parts of water was added to 100 parts of the solid content of the emulsion, and then 30 parts of thermally expandable hollow fine particles and 100 parts of aluminum hydroxide were added. Thus, a composition for a flame-retardant foam sheet was prepared. This composition was evaluated in the same manner as in Example 1. The results are shown in Tables 1 and 2.

Comparative Example 1 In Example 1, polyvinyl alcohol (degree of polymerization: 50
0, 2 parts of nonionic surfactant (polyoxynonylphenyl ether) and anionic surfactant (sodium alkylbenzenesulfonate) instead of the saponification degree of 88.3 mol%, the polymerization degree of 300 and the saponification degree of 88.1 mol% ) The procedure was performed in the same manner as in Example 1 except that 2 parts were used. The results are shown in Tables 3 and 4.

Comparative Example 2 14 parts of polyvinyl alcohol (polymerization degree: 500, saponification degree: 88.3 mol%) and 100 parts of ion-exchanged water were put into a glass polymerization vessel equipped with a stirrer, a nitrogen inlet, and a thermometer and dissolved by heating. did. After cooling, the pH was adjusted to 4.0 with sulfuric acid, and the temperature was increased to 70 ° C. while performing nitrogen bubbling. The stirring was set to 150 rpm, 28 parts of vinyl acetate was added, and 30 parts of a 2% Rongalite aqueous solution was further added.
Polymerization was started by successively adding 0.4% aqueous hydrogen peroxide.
Thirty minutes after the start of the polymerization, 112 parts of vinyl acetate were uniformly dropped over 2 hours. Using this emulsion, a composition was prepared and evaluated in the same manner as in Example 1. The results are shown in Tables 3 and 4.

Comparative Example 3 A nonionic surfactant (polyoxyethylene nonylphenyl ether) (2 parts) and an anionic surfactant (sodium alkylbenzene sulfonate) were placed in a glass polymerization vessel equipped with a stirrer, a nitrogen inlet, and a thermometer. 1.75 parts and 130 parts of ion-exchanged water were added and stirred and dissolved. After adjusting the pH to 4.0 with sulfuric acid, nitrogen bubbling was performed for 7 hours.
The temperature was raised to 5 ° C. The stirring was performed at 150 rpm, and 18 parts of methyl methacrylate and 12 parts of 2-ethylhexyl acrylate were added. Further, 20 parts of a 1% aqueous solution of potassium persulfate was added to initiate polymerization. One hour after the start of the polymerization, 72 parts of methyl methacrylate, 2-ethylhexyl acrylate 4
8 parts, 2 parts of a nonionic surfactant (polyoxyethylene nonylphenyl ether), and 1.75 parts of an anionic surfactant (sodium alkylbenzenesulfonate) were uniformly dropped over 2 hours. After completion of the dropwise addition, the temperature was raised to 80 ° C., and the polymerization was completed in one hour. Solids concentration 5
A 0.2% methyl methacrylate-2-ethylhexyl acrylate copolymer emulsion was obtained. Using this emulsion, a composition was prepared and evaluated in the same manner as in Example 1. The results are shown in Tables 3 and 4.

Comparative Example 4 In Example 1, the monomer composition was the same, and 5 parts of polyvinyl alcohol (degree of polymerization: 300, degree of saponification: 88.2 mol%) was used as a stabilizer to obtain ethylene / ethylene copolymer obtained by one-stage polymerization. The procedure was performed in the same manner as in Example 1 except that a terpolymer emulsion of vinyl acetate / acryl was used.
The results are shown in Tables 3 and 4.

Comparative Example 5 2 parts of polyvinyl alcohol (polymerization degree: 500, saponification degree: 88.3 mol%) and a nonionic surfactant (polyoxyethylene) were placed in a glass polymerization vessel equipped with a stirrer, a nitrogen inlet, and a thermometer. 2 parts of nonylphenyl ether) and 130 parts of ion-exchanged water were dissolved under heating, stirred, cooled, and then cooled.
After the pH was adjusted to 4.0 with sulfuric acid, the mixture was transferred to a stainless steel polymerization vessel. 68 parts of vinyl acetate, 10 parts of methyl methacrylate, 1 part of acrylic acid and 1 part of N-methylolacrylamide were added, and the temperature was raised to 60 ° C. while performing nitrogen bubbling.
Ethylene was charged at 50 Kg / cm ² , 30 ml of 2% Rongalite was added, and 0.4% hydrogen peroxide was sequentially added to initiate polymerization. Four hours after the start of the polymerization, an ethylene / vinyl acetate / methyl methacrylate / acrylic acid / N-methylolacrylamide copolymer emulsion having a solid content of 50.0% was obtained. Using this emulsion, a composition was prepared and evaluated in the same manner as in Example 1. The results are shown in Tables 3 and 4.

Comparative Example 6 The procedure of Example 1 was repeated except that the polymer (B) (Tg-64 ° C.) obtained using 10 parts of methyl methacrylate and 94 parts of 2-ethylhexyl acrylate as the acrylic monomer was used. It carried out similarly to Example 1. The results are shown in Tables 3 and 4.
Shown in

COMPARATIVE EXAMPLE 7 A polymer (A) obtained in Example 1 with 30.5 parts of vinyl acetate and 60 kg / cm ^{2 of} ethylene, and having an ethylene content of 35% by weight and a Tg of 25 ° C. The procedure was performed in the same manner as in Example 1 except that vinyl acetate copolymer) was used. The results are shown in Tables 3 and 4.

Comparative Example 8 In Example 1, (D) the amount of the heat-expandable hollow fine particles was changed to 3
The procedure was performed in the same manner as in Example 1 except that some parts were used. Table 3 shows the results
Are shown in FIGS.

Comparative Example 9 In Example 1, the amount of (D) the heat-expandable hollow fine particles was changed to 8
The operation was performed in the same manner as in Example 1 except that 0 part was used. The results are shown in Tables 3 and 4.

Comparative Example 10 The procedure of Example 1 was repeated, except that the amount of the inorganic filler (C) was 20 parts. The results are shown in Tables 3 and 4.

[0043]

[Table 1]

[0044]

[Table 2]

[0045]

[Table 3]

[0046]

[Table 4]

[0047]

According to the present invention, no harmful chlorine gas is generated at the time of incineration, excellent flame retardancy that is friendly to the global environment and work environment, mechanical strength, water resistance, alkali resistance, blocking resistance, The present invention can provide an emulsion and a composition for a flame-retardant foamed sheet which are excellent in cracking property and further excellent in embossing properties when embossing.

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification code FI Theme coat ゛ (Reference) C08L 31/02 C08L 31/02 D21H 27/20 D21H 27/20 A F term (Reference) 4F074 AA16 AA17 AA37 AA41 AA48 AA49 AA98 AB00 AC17 AC19 AC20 AC26 AC27 AC30 AC32. GL01 HA07 4L055 AG17 AG57 AG59 AG64 AG71 AG89 AG97 AH02 AH33 AH34 AH37 AH48 AJ04 AJ08 AJ10 BE08 BE20 EA20 EA32 FA13 FA19 FA30 GA23

Claims (4)

[Claims] An emulsion polymerization of a (meth) acrylate monomer in the presence of an emulsion containing a vinyl alcohol-based polymer as a dispersant and a polymer composed of a vinyl ester-based monomer as a dispersoid. The weight ratio of the polymer (A) composed of a vinyl ester monomer and the polymer (B) composed of a (meth) acrylate monomer obtained in (A) /
(B) = 70/30 to 20/80, and the (A) component has a glass transition temperature of -15C to 30C, and the (B) component has a glass transition temperature of -15C to 20C. Emulsion for flexible foam sheet. 2. The flame-retardant foam sheet emulsion according to claim 1, wherein the component (A) is an ethylene-vinyl acetate copolymer having an ethylene content of 5 to 30% by weight. 3. The emulsion (C) according to claim 1 or 2, comprising a heat-expandable hollow microsphere (D) and an inorganic filler (E), wherein (D) 5 per 100 parts by weight of a solid content of (C). (E) 50 to 300 parts by weight of the emulsion composition for a flame-retardant foamed sheet. 4. A flame-retardant foamed sheet obtained by applying the emulsion composition for a flame-retardant foamed sheet according to claim 3 on a substrate, drying and heating and foaming.