JPH05125085A - Flame-resistant polyolefin foam crosslinked with phosphate ester - Google Patents

Abstract

PURPOSE:To obtain the subject foam not lowered in the formability, strength and elongation and useful for building materials, etc., by impregnating a polyolefin with a specific amount of specified phosphate esters and subsquently irradiating the impregnated foam with ionizing radiations to produce the polymer of the derivative on the surface, etc., of the foam. CONSTITUTION:(A) 100 pts. wt. of a polyolefin foam is impregnated with (B) 10-200 pts. wt. of one kind of more of new phosphate esters of formula I [R1, R3 are each H, methyl; R2 is (halogen-substituted)alkyleneoxy, etc.,], formulas II and III [R2, R3 are each (halogen-substituted) 1-5C alky, H; (n) is 0, 1], and formula IV [R2 is (halogen-substituted)alkyleneoxy, etc.; R3 is (halogen- substituted)alkyl, H; (m) is 1-3], and subsequently irradiated with ionizing radiations such as an alpha ray preferably in a dose of 1-10 Mrad to produce the polymer of the derivative on the surface of the foam and on the inner surfaces of the fine pores of the foam.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a flame-retardant polyolefin foam. More specifically, the present invention relates to a polyolefin foam imparted with flame retardancy by producing a flame retardant polymer on the surface and inside thereof.

[0002]

2. Description of the Related Art In recent years, polyolefin foam has been used for many purposes because of its heat insulating property and cushioning property.
However, polyolefin resins such as polyethylene have the drawback that they are extremely flammable and have a high heat of combustion, which may cause inconveniences when the polyolefin foam is used in the field of building materials and the like. For example, when polyolefin foam is laminated to a steel plate and used as a heat insulating steel plate, the thickness of the polyolefin foam is limited to be certified as a quasi-incombustible agent, so the polyolefin foam cannot be thickened to improve heat insulation. ..

Various methods have hitherto been carried out in order to improve this drawback. Generally, as a method for imparting flame retardancy to a polyolefin foam, a method in which a large amount of inorganic powder is added or an aromatic bromine-based flame retardant method is used. A method of adding a combustor is used. However, while the method of adding an inorganic powder provides excellent flame retardancy, it has drawbacks such as a reduction in foaming ratio and foam elongation.Therefore, the method of adding an aromatic bromine flame retardant is There is a problem with the toxicity of. Therefore, a method for imparting flame retardancy to a polyolefin foam by electron beam graft-polymerizing a vinylphosphonate-based oligomer inside and on the surface of the foamed polyolefin foam has been devised in recent years (Japanese Patent Laid-Open No. 22317/1990). However, in this method, the polymerization rate per unit electron dose of the oligomer (trade name: Phiroll 76; manufactured by Meisho Kagaku Co., Ltd.) is low, so that the unpolymerized oligomer is eluted in the washing step after electron beam irradiation, resulting in a relatively phosphorus content. There is a drawback that the content is reduced and the flame retardancy of the polyolefin foam is not sufficient.

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned drawbacks and to provide a polyolefin foam having excellent flame retardancy.

[0005]

The present invention includes chemical formulas 1 and 1
At least one phosphate ester of the phosphate ester represented by Chemical formula 4 is impregnated in an amount of 10 to 200 parts by weight with respect to 100 parts by weight of the polyolefin foam, followed by irradiation with ionizing radiation to obtain the surface of the polyolefin foam and the surface of the fine pores. A flame-retardant polyolefin foam characterized by producing a polymerized product of the phosphoric acid ester in, and a method for producing the same.

Examples of the material of the polyolefin foam which is the object of the present invention include polyethylene, ethylene vinyl acetate copolymer, polypropylene, polyvinyl chloride and polyvinylidene chloride.

The flame-retardant polyolefin foam of the present invention can be obtained as follows. As a method for incorporating the phosphoric acid ester into the present polyolefin foam, first, the phosphoric acid ester is dissolved in a solvent described below so as to be 10 to 100 wt%, and then the polyolefin foam is immersed in the solution.

Next, an extra solution is squeezed from the taken out polyolefin foam, and particularly when a solvent is added, it is sufficiently air-dried or dried under reduced pressure to evaporate the solvent.

Examples of the solvent used here include methanol, ethanol, acetone, tetrahydrofuran, ethyl acetate and water.

After drying, the polyolefin foam is irradiated with ionizing radiation in an inert gas atmosphere, a vacuum, or an air atmosphere. Gamma rays and electron beams are conveniently used as the ionizing radiation. For example, the foam is preferably 1. ~ 1.0X10 ⁷ rad /
Irradiating a dose of 1 to 10 Mrad at a dose rate of 2 seconds to form a flame-retardant polymer on the surface of the foam and the surface of the micropores, and then washing the uncured derivative with water if necessary. The present invention can be obtained by removing. If the content of the phosphoric acid ester is 10% or less, high flame retardancy cannot be obtained, and if it is 200% or more, there is a problem in the physical properties and profitability of the foam, which is not preferable. Further, when the amount of the crosslinking agent is 5 parts by weight or less with respect to 100 parts by weight of the phosphoric acid ester, high flame retardancy cannot be obtained, and when it is 300 parts by weight or more, there is a problem in the physical properties and profitability of the foam, which is preferable. Absent.

[0011]

The flame-retardant polyolefin foam of the present invention imparts flame-retardant properties by forming a flame-retardant polymer on the surface and on the surface inside the fine pores after foaming as described above. Flame retardancy can be obtained without causing a decrease in strength and elongation. Further, since the phosphorus-containing compound used is highly reactive, it is possible to efficiently incorporate a flame-retardant polymer into a polyolefin foam even with an electron beam irradiation device of a low acceleration voltage, and easily obtain a flame-retarded polyolefin foam. Obtainable.

Method for Measuring Remaining Rate of Flame Retardant Component The weight of the original foam measured before the start of the examples and the weight of the flame retardant polyolefin foam obtained in each example were measured. The rate of increase was measured.

[Equation 1]

The residual rate of the flame-retardant component was calculated from the equation 2.

[Equation 2]

Combustion test: According to JIS A9415. Starting specimen length 15 cm.

[0015]

Example 1 A sheet of ethylene vinyl acetate copolymer of 170 × 130 × 5 mm (manufactured by Sanwa Kako Co., Ltd., Obsel LC-300 ⁿ³ , apparent density 0.02)
7 g / cm ² ) was impregnated with N- (dimethylphosphonomethyl) acrylamide, and this was irradiated with an electron beam. Irradiation was performed at room temperature, and an electron beam of 175 KeV was applied for 10 Mrad. After irradiation, the foam was washed with water to remove unreacted substances and low molecular weight polymers. Various tests were performed below. The measuring method is to measure the residual rate of the flame retardant component, and then to JIS A
A flame test based on 9514 was performed to evaluate flame retardancy. The results are shown in Table 1.

[0016]

Example 2 A flame-retardant foam was obtained in the same manner as in Example 1 except that N, N bis (phosphonomethyl) acrylamide was used as the phosphorus-containing compound. Table 1 shows the residual ratio of the flame-retardant component after cleaning and the result of the combustion test based on JIS A9415.

[0017]

EXAMPLE 3 Mono (2-acryloyloxyethyl) acid phosphate and di (2-acryloyloxyethyl) acid phosphate were used as phosphorus-containing compounds in a ratio of 1:
A flame-retardant foam was obtained in the same manner as in Example 1 except that 1 mixture was used. The residual rate of flame retardant components after cleaning,
Table 1 shows the combustion test results based on JIS A9415.

[0018]

EXAMPLE 4 Mono (2-methacryloyloxyethyl) acid phosphate and di (2-
A flame-retardant foam was obtained in the same manner as in Example 1 except that a 1: 1 mixture of methacryloyloxyethyl) acid phosphate was used. Table 1 shows the residual rate of flame-retardant components after cleaning and the combustion test results based on JIS A9415.
Shown in.

[0019]

Example 5 A flame-retardant foam was obtained in the same manner as in Example 1 except that dimethyl (2-acryloyloxyethyl) phosphate was used as the phosphorus-containing compound.
Table 1 shows the residual rate of the flame-retardant component after cleaning and the result of the combustion test based on JIS A9415.

[0020]

Example 6 A flame-retardant foam was obtained in the same manner as in Example 1 except that N- (dihydroxyphosphonomethyl) acrylamide was used as the phosphorus-containing compound. Table 1 shows the residual ratio of the flame-retardant component after cleaning and the result of the combustion test based on JIS A9415.

[0021]

Example 7 A flame-retardant foam was obtained in the same manner as in Example 1 except that N- (diethylphosphonomethyl) acrylamide was used as the phosphorus-containing compound. Table 1 shows the residual ratio of the flame-retardant component after cleaning and the result of the combustion test based on JIS A9415.

[0022]

[Example 8] Flame retardant in the same manner as in Example 1 except that a 6: 4 mixture of N- (dimethylphosphonomethyl) acrylamide and a compound represented by the following chemical formula 6 was used as a phosphorus-containing compound. Got the form. Table 1 shows the residual ratio of the flame-retardant component after cleaning and the result of the combustion test based on JIS A9415.

[0023]

Example 9 Flame-retardant property in the same manner as in Example 1 except that an 8: 2 mixture of N- (dimethylphosphonomethyl) acrylamide and a compound represented by the following chemical formula 6 was used as a phosphorus-containing compound. Got the form. Table 1 shows the residual ratio of the flame-retardant component after cleaning and the result of the combustion test based on JIS A9415.

[0024]

[Example 10] Flame retardant in the same manner as in Example 1 except that an 8: 2 mixture of N- (diethylphosphonomethyl) acrylamide and a compound represented by the following chemical formula 6 was used as a phosphorus-containing compound. Got the form. Table 1 shows the residual rate of the flame-retardant component after cleaning and the result of the combustion test based on JIS A9415.

[0025]

EXAMPLE 11 Flame retardance was the same as in Example 1 except that a 9: 1 mixture of N- (dimethylphosphonomethyl) acrylamide and N, N-dimethylaminopropylacrylamide was used as the phosphorus-containing compound. Got the form. Flame retardant component residual rate after cleaning and JIS A9415
The results of the combustion test based on Table 1 are shown in Table 1.

[0026]

Example 12 A flame-retardant foam was obtained in the same manner as in Example 1 except that a 9: 1 mixture of N- (dimethylphosphonomethyl) acrylamide and tetraethylene glycol diacrylate was used as the phosphorus-containing compound. It was Table 1 shows the residual ratio of the flame-retardant component after cleaning and the result of the combustion test based on JIS A9415.

[0027]

Example 13 Flame-retardant property in the same manner as in Example 1 except that an 8: 2 mixture of N- (dimethylphosphonomethyl) acrylamide and 1,6-hexanediol diacrylate was used as a phosphorus-containing compound. Got the form. Table 1 shows the residual ratio of the flame-retardant component after cleaning and the result of the combustion test based on JIS A9415.

[0028]

Example 14 Mono (2-acryloyloxyethyl) acid phosphate as a phosphorus-containing compound and the following compound 7
A flame-retardant foam was obtained in the same manner as in Example 1 except that a 1: 1 mixture of compounds represented by Table 1 shows the residual rate of the flame-retardant component after cleaning and the result of the combustion test based on JIS A9415.

[0029]

Example 15 Flame retardant was carried out in the same manner as in Example 1 except that a 1: 1 mixture of mono (2-methacryloyloxyethyl) acid phosphate and a compound represented by the following chemical formula 8 was used as the phosphorus-containing compound. Got a sex foam. Table 1 shows the residual ratio of the flame-retardant component after cleaning and the result of the combustion test based on JIS A9415.

[0030]

Example 16 Mono (2-acryloyloxyethyl) acid phosphate as a phosphorus-containing compound and the following compound 7
9 of the compound represented by the following and the compound represented by the following chemical formula 6:
A flame-retardant foam was obtained in the same manner as in Example 1 except that the 9: 2 mixture was used. Table 1 shows the residual rate of flame-retardant components after cleaning and the combustion test results based on JIS A9415.
Shown in.

[0031]

Example 17 Mono (2-methacryloyloxyethyl) acid phosphate as a phosphorus-containing compound, a compound represented by the following chemical formula 8 and a compound represented by the following chemical formula 9:
A flame-retardant foam was obtained in the same manner as in Example 1 except that the 9: 2 mixture was used. Table 1 shows the residual rate of flame-retardant components after cleaning and the combustion test results based on JIS A9415.
Shown in.

[0032]

Example 18 As a phosphorus-containing compound, a mixture of mono (2-methacryloyloxyethyl) acid phosphate, a compound represented by the following chemical formula 8 and N, N-dimethylaminopropylacrylamide in a ratio of 9: 9: 2 was used. A flame-retardant foam was obtained in the same manner as in Example 1 except for the above. Table 1 shows the residual ratio of the flame-retardant component after cleaning and the result of the combustion test based on JIS A9415.

[0033]

Example 19: Except that a 9: 9: 2 mixture of mono (2-methacryloyloxyethyl) acid phosphate, a compound represented by the following chemical formula 8 and tetraethylene glycol diacrylate was used as the phosphorus-containing compound. A flame-retardant foam was obtained in the same manner as in Example 1. Table 1 shows the residual ratio of the flame-retardant component after cleaning and the result of the combustion test based on JIS A9415.

[0034]

Example 20 As a phosphorus-containing compound, a mixture of mono (2-methacryloyloxyethyl) acid phosphate, a compound represented by the following chemical formula 8 and 1,6-hexanediol diacrylate in a ratio of 9: 9: 2 was used. A flame-retardant foam was obtained in the same manner as in Example 1 except for the above. Table 1 shows the residual ratio of the flame-retardant component after cleaning and the result of the combustion test based on JIS A9415.

[0035]

Comparative Example 1 A flame-retardant foam was obtained in the same manner as in Example 1 except that Phylol 76 was used as the phosphorus-containing compound. Flame retardant component residual rate after cleaning and JIS A
The combustion test results based on 9415 are shown in Table 1.

As a result of the combustion test, Example 1 was compared with Comparative Example 1.
All of Nos. 20 to 20 had a high residual rate of the flame retardant component, and thus the flame retardancy of the treated foam was improved and the combustion length was shortened.

[Table 1]

[Chemical 6]

[Chemical 7]

[Chemical 8]

Continued Front Page (72) Inventor Taku Zama 1-1, Suzuki-cho, Kawasaki-ku, Kawasaki-shi, Kanagawa Ajinomoto Co., Inc. Central Research Laboratory

Claims (5)

[Claims] 1. An acidic phosphoric acid ester represented by Chemical Formula 1 [R1 and R3 may be hydrogen or a methyl group, R2 may be (a) an alkyleneoxy group which may be substituted with a halogen or an alkyl group, or (b) a halogen or an alkyl group may be substituted (CH ₂ CH ₂ O) _n Group (n is 2 to
4) or (c) an alkylene group which may be substituted with a halogen or an alkyl group, X is -O- or-
Represents NH-. ] 2. A flame-retardant polyolefin foam obtained by graft-polymerizing 10 to 200 parts by weight of the phosphoric acid ester represented by Chemical formula 1 to Chemical formula 4 on the surface of 100 parts by weight of the polyolefin foam and the surface of the fine pores thereof. 3. At least one of the phosphoric acid esters represented by Chemical formulas 1 to 4 is impregnated in an amount of 10 to 200 parts by weight with respect to 100 parts by weight of the polyolefin foam, and then the surface of the polyolefin foam is irradiated with ionizing radiation. A method for producing a flame-retardant polyolefin foam, characterized in that a polymerized product of the derivative is formed on the inner surface of fine pores. [Chemical 2] [However, R1 represents hydrogen or a methyl group, R2 and R3 represent (1) an alkyl group having 1 to 5 carbon atoms which may be substituted with halogen, or (2) hydrogen. n represents an integer of n = 0,1. ] [Chemical 3] [However, R1 represents hydrogen or a methyl group, R2 and R3 represent (1) an alkyl group having 1 to 5 carbon atoms which may be substituted with halogen, or (2) hydrogen. n is n = 0,1
Represents the integer. ] [Chemical 4] [However, m = 1 to 3 is an integer, R1 is hydrogen or a methyl group, R2 is (a) an alkyleneoxy group which may be substituted with a halogen or an alkyl group, or (b) is optionally substituted with a halogen or an alkyl group. (CH ₂ CH
₂ O) _n group (n is an integer of 2 to 4) or (c) an alkylene group which may be substituted with a halogen or an alkyl group, R3 is (1) an alkyl group which may be substituted with a halogen, or (2) Represents hydrogen. ] 4. At least one of the phosphoric acid esters represented by Chemical formulas 1 to 4 is polymerized on the surface of a polyolefin foam and the surface of micropores through at least one cross-linking agent represented by Chemical formula 5. A method for producing a flame-retardant polyolefin foam, which is characterized. [Chemical 5] [R1, R4 and R5 represent hydrogen or a methyl group, and R3 represents (1) an alkyl group which may be substituted with halogen or (2) hydrogen. R2 may be (a) an alkylene group that may be substituted with a halogen or an alkyl group or a hydroxyl group, or (b) may be substituted with a halogen or an alkyl group or a hydroxyl group (CH2CH2O) nCH2.
It represents a CH2 group (n is an integer of 1 to 3). X, Y, Z are
Represents -O- or -NH-. l, m, n are l,
It represents an integer of m, n ≧ 0 and l + m + n ≧ 1. ] 5. A mixture of 5 to 300 parts by weight of at least one crosslinking agent represented by Chemical formula 5 with respect to 100 parts by weight of at least one phosphoric ester of Chemical formulas 1 to 4 is added to 100 parts by weight of polyolefin foam. On the other hand, 10 to 200 parts by weight is impregnated and then irradiated with ionizing radiation, and the phosphoric acid ester is polymerized on the surface of the polyolefin foam and the inner surface of the fine pores through a cross-linking agent. Polyolefin foam. [Chemical 5] [R1, R4 and R5 represent hydrogen or a methyl group, and R3 represents (1) an alkyl group which may be substituted with halogen or (2) hydrogen. R2 may be (a) an alkylene group that may be substituted with a halogen or an alkyl group or a hydroxyl group, or (b) may be substituted with a halogen or an alkyl group or a hydroxyl group (CH2CH2O) nCH2.
It represents a CH2 group (n is an integer of 1 to 3). X, Y, Z are
Represents -O- or -NH-. l, m, n are l,
It represents an integer of m, n ≧ 0 and l + m + n ≧ 1. ]