JPH0570623A - Composition for flame-retardant resin foamed body, flame-retardant resin foamed body and its production - Google Patents

Abstract

PURPOSE:To obtain the title composition useful for building materials, having low smoking, hardly evolving harmful substances to cause an environmental pollution in combustion, having excellent heat insulating properties and soundproofing properties, comprising a specific flame-retardant and a specific low-density PE-based resin in a specific ratio. CONSTITUTION:The objective composition comprising (A) a halogenated phosphorus-containing compound-based flame-retardant containing 50-85wt.% phosphorus and halogen, having 150-250 deg.C melting point and 0.2-50mum particle diameter and (B) a low-density PE resin having 0.910-0.930g/cm<3> density and 0.5-50g/10 minutes melt flow rate in a weight ratio of the component A/B of 0.05-0.45. The composition is molded, heated and crosslinked and foamed to give flame-retardant resin foamed body.

Description

Detailed Description of the Invention

[0001]

The present invention relates to a resin foam composition,
TECHNICAL FIELD The present invention relates to a resin foam and a method for producing a resin foam, and particularly to a composition for a flame-retardant resin foam, a flame-retardant resin foam and a method for producing a flame-retardant resin foam.

[0002]

2. Description of the Related Art In general, polyolefin resin foams are lightweight and have excellent heat insulation and sound insulation properties, so that they are used in the fields of building materials, industrial materials, daily necessities and interior materials for vehicles. Widely used. However, since the polyolefin resin foam easily burns, various attempts have been made to make it flame-retardant. For example, as a flame-retardant polyolefin resin foam, a flame retardant containing a halogenated aromatic compound such as decabrom diphenyl ether or hexabromobenzene and a flame retardant auxiliary such as antimony trioxide, or tetrabromobisphenol A glycidyl ether. It is known that such an epoxy-based flame retardant is added.

[0003]

The conventional flame-retardant polyolefin resin foam to which a flame-retardant agent containing a halogenated aromatic compound and a flame-retardant aid is added produces toxic decomposition products during combustion. Therefore, there is a risk of environmental pollution. On the other hand, the resin foam to which the epoxy-based flame retardant is added generates a large amount of black smoke when burned when a large amount of the flame retardant is used to enhance flame retardancy.

It is an object of the first, second and third inventions that a flame-retardant resin having low smoke emission and capable of forming a flame-retardant resin foam which hardly produces harmful substances that cause environmental pollution during combustion. An object is to provide a composition for foam. A fourth object of the present invention is to provide a flame-retardant resin foam which has low smoke generation and hardly generates harmful substances that cause environmental pollution during combustion.

An object of the fifth invention is to provide a method for producing a flame-retardant resin foam according to the fourth invention.

[0006]

The composition for flame-retardant resin foam according to the first invention contains phosphorus and halogen in an amount of 50 to 85.
Halogenated phosphorus-containing compound-based flame retardant (A)
And a low density polyethylene resin (B) having a density of 0.910 to 0.930 g / cm ³ and a melt flow rate of 0.5 to 50 g / 10 min, and A / B is a weight ratio of 0. It is set to 05 to 0.45.

The flame-retardant resin foam composition according to the second aspect of the present invention is the flame-retardant resin foam composition according to the first aspect of the invention, which has a melting point of 150 to 250 ° C. as the flame retardant (A). And the particle size is 0.2 to 50 μm.
The composition for flame-retardant resin foam according to the third invention is a polyolefin resin different from the low-density polyethylene resin (B) in the composition for flame-retardant resin foam according to the first or second invention. Of less than 60% by weight based on the total resin components.

The flame-retardant resin foam according to the fourth invention comprises a halogenated phosphorus-containing compound flame retardant (A) containing phosphorus and halogen in an amount of 50 to 85% by weight and a density of 0.910 to 0.
930 g / cm ³ and a melt flow rate of 0.
A low-density polyethylene resin (B) for 5 to 50 g / 10 minutes, and a composition for flame-retardant resin foam, wherein A / B is set to a weight ratio of 0.05 to 0.45. 15 ~
It is 60% and the expansion ratio is set to 2 to 50 times.

The method for producing a flame-retardant resin foam according to the fifth aspect of the invention includes the following steps. A halogenated phosphorus-containing compound-based flame retardant (A) containing 50 to 85% by weight of phosphorus and halogen, and a density of 0.910.
A low-density polyethylene resin (B) having a melt flow rate of 0.530 g / cm ³ and a flow rate of 0.5 to 50 g / 10 min, wherein A / B is 0.05 to 0.45 by weight.
The step of molding the composition for a flame-retardant resin foam set in 1. ◎ A step of heating the molded composition for flame-retardant resin foam to crosslink and foam.

******** Flame Retardant (A) The flame retardant used in the present invention contains phosphorus and halogen simultaneously in the molecular skeleton. It is a halogenated phosphorus-containing compound. The effect of the present invention cannot be realized with a flame retardant containing only phosphorus or halogen or a mixture thereof.

In the above-mentioned halogenated phosphorus-containing compound, the total content of phosphorus and halogen is 50 to 85% by weight, preferably 60 to 80% by weight. When the content of phosphorus and halogen is less than 50% by weight, a large amount of flame retardant must be used in order to enhance flame retardancy, resulting in a decrease in mechanical strength of the foam. On the other hand, if the content exceeds 85% by weight, the stability of the flame retardant decreases, making it difficult to increase the flame retardancy.

The halogenated phosphorus-containing compound preferably has a melting point of 150 to 250 ° C. Especially, the melting point is 15
A halogen-containing phosphate ester flame retardant containing 0 to 250 ° C., a particle size of 0.2 to 50 μm, and chlorine or bromine as a halogen is preferable. When the melting point of this flame retardant is less than 150 ° C., void-like large bubbles are likely to be generated in the foam. On the other hand, when the temperature exceeds 250 ° C., the flame retardant is hard to be uniformly dispersed in the foam, so that the effect of the flame retardant is hard to be imparted to the entire foam. On the other hand, if the particle size is less than 0.2 μm, the bulk density of the flame retardant increases, so the dispersibility in the resin component decreases, and coarse bubbles may be generated in the foam. In addition, secondary aggregation is likely to occur to coarse particles, which may cause coarse bubbles in the foam. vice versa,
When it exceeds 50 μm, the cell strength of the foam is weakened and the mechanical strength of the foam is lowered. Further, since the foaming gas is likely to escape, it is difficult to obtain a foam having a high expansion ratio. The halogen component may be either chlorine or bromine, but bromine is particularly preferable. When a flame retardant containing bromine is used, high flame retardancy can be realized even with a small amount of addition. Examples of the halogen-containing phosphate ester flame retardant containing bromine include tris (tribromoneopentyl) phosphate and tris (tribromophenyl) phosphate.

As the flame retardant, in addition to the halogenated phosphorus-containing compound described above, another type of halogen-based flame retardant having a melting point of 150 ° C. or higher may be used in combination. However, the amount of various halogen-based flame retardants added is 25% of that of the above-mentioned halogenated phosphorus-containing compound.
It is preferably set to not more than weight%. Low Density Polyethylene Resin (B) The low density polyethylene resin (B) used in the present invention is
The density is 0.910 to 0.930 g / cm ³ , and preferably 0.920 to 0.925 g / cm ³ . The melt flow rate is 0.5 to 50 g / 10 minutes, preferably 3 to 10 g / 10 minutes. Density is 0.910g / cm
If it is less than ³ , the crystallinity of the resin will be low and the mechanical properties of the foam will be poor. In addition, the composition of the present invention is blocked and becomes difficult to handle in the process of producing a foam. On the other hand, if it exceeds 0.930 g / cm ³ , the crystallinity increases and it becomes difficult to crosslink. On the other hand, when the melt flow rate is less than 0.5 g / 10 minutes, the composition has poor melt flowability, and thus the foaming agent is decomposed by shearing heat generation in the step of introducing the composition into an extruder and molding the composition into a sheet. However, a sheet suitable for foaming cannot be obtained. On the contrary, 50g / 10
If the amount exceeds the limit, the flowability of the composition becomes too good, and it becomes difficult to maintain the sheet shape unless a special cooling device is used in the sheet process, and as a result, a sheet suitable for foaming cannot be obtained.

The flame-retardant resin foam composition of the present invention may contain, as a resin component, a polyolefin resin other than the above-mentioned low density polyethylene resin (B). However, the amount of the polyolefin resin mixed must be set to less than 60% by weight of the entire resin component. If the mixed amount exceeds 60% by weight, the flame retardant effect of the above flame retardant (A) will be reduced. Further, the resin component becomes difficult to crosslink.

As the polyolefin resin other than the low density polyethylene resin (B), ethylene-propylene copolymer, linear low density polyethylene, high density polyethylene, ethylene-vinyl acetate copolymer, ethylene-acrylic acid copolymer Examples thereof include a polymer, an ethylene- (meth) alkyl acrylate copolymer, or a terpolymer obtained by further copolymerizing these copolymers with maleic anhydride as a third component. Other Components The composition for flame-retardant resin foam according to the present invention may contain a decomposable foaming agent, if necessary, in addition to the above-mentioned essential components. As the decomposable foaming agent, either an organic foaming agent or an inorganic foaming agent may be used. Examples of the organic decomposition type foaming agent include azodicarbonamide, N, N'-dinitrosopentamethylenetetramine, p, p'-oxybenzenesulfonyl hydrazide and the like. As the inorganic decomposing type foaming agent, sodium carbonate, ammonium carbonate,
Examples include ammonium bicarbonate and calcium azide.

If necessary, a heat stabilizer, a weather resistance agent, a flame retardant aid (for example, an antimony compound), a dispersant, a cross-linking agent, and a cross-linking remover may be added to the composition of the present invention. .. These additives can be added within a range that does not impair the object of the present invention. Mixing ratio In the composition for a flame-retardant resin foam of the present invention, the flame retardant (A)
As for the component ratio of the low density polyethylene resin (B), the weight ratio A / B is 0.05 to 0.45, preferably 0.07 to.
It is set to 0.20. When A / B is less than 0.05, the amount of the flame retardant is insufficient, so that the flame retardancy of the foam decreases. On the other hand, when it exceeds 0.45, the flame retardant increases, so that the mechanical properties of the foam deteriorate. Further, when the foam is burned, harmful gas may be generated due to decomposition of the flame retardant. Method for producing flame-retardant resin foam Here, using the composition for flame-retardant resin foam described above,
A case of producing a continuous sheet-shaped flame-retardant resin foam will be described as an example.

First, a flame-retardant resin foam composition is produced. This composition can be produced by mixing the above-mentioned resin component, other components such as a flame retardant and a foaming agent using a Henschel mixer, for example. At this time, the resin components are not mixed together at the same time but only 200 to 30
It is preferable to mix at a relatively low speed of 0 times / minute, and after the resin components are sufficiently mixed, the flame retardant and other components are added and mixed at a high speed. The temperature at the time of mixing depends on the contents of the mixed components, but it is usually preferable to set the temperature at 70 ° C. or lower.

Next, the obtained composition for flame-retardant resin foam is supplied to a heated extruder with a vent and extruded from a T-die of the extruder to form a continuous sheet without air bubbles due to air entrainment. And then roll it up. Next, the obtained continuous sheet-shaped composition for resin foam is continuously introduced into a foaming furnace to foam. At this time, the polyethylene resin (B) and the polyethylene resin (C) simultaneously undergo a crosslinking reaction. As a result, a continuous sheet-shaped crosslinked resin foam is obtained. A known method can be adopted as the foaming method. Specifically, vertical hot air foaming method, horizontal hot air foaming method,
A horizontal chemical solution foaming method or the like can be adopted.

In the above-mentioned manufacturing method, the foaming agent is added to the foam composition, but a foaming method without using the foaming agent may be adopted. For example, an extrusion foaming method in which an evaporative foaming agent is dissolved in a composition under pressure during melt extrusion and foamed simultaneously during extrusion, and a block foaming method in which foaming is performed simultaneously with melt formation in a mold under pressure are adopted. obtain. Moreover, in the above-described manufacturing method, a peroxide-based crosslinking agent may be added to the flame-retardant resin foam composition in advance. Examples of the peroxide type crosslinking agent include dicumyl peroxide, tertiary butyl perbenzoate, ditertiary butyl peroxide and the like. These crosslinkers are
It is preferable to add 0.5 to 5 weight blades to the resin component.

In this manufacturing method, the crosslinking reaction between the resins is promoted by the action of the crosslinking agent in the foaming step of the flame-retardant resin foam composition. Furthermore, in the above-mentioned manufacturing method, after molding the flame-retardant resin foam composition into a predetermined shape,
The resin composition in the composition may be partially crosslinked by irradiating the formed composition with an electron beam. For example, when the composition is formed into a sheet, an electron beam is irradiated so that the degree of crosslinking gradually decreases from both sides of the sheet toward the center.
In this case, the crosslinking reaction of the central portion in the thickness direction proceeds during foaming. In this production method, the above-mentioned peroxide-based crosslinking agent may be added to the composition for flame-retardant resin foam. Flame-retardant resin foam The flame-retardant resin foam of the present invention obtained by the above-mentioned production method has a degree of crosslinking of 15 to 60%, preferably 20 to 50%.
Is. The expansion ratio is 2 to 50 times, preferably 5 to
It is 40 times. If the degree of cross-linking is less than 15%, the foaming gas is likely to escape during foaming, making it difficult to achieve high foaming.
Also, traces of gas escape remain on the surface of the foam, causing surface roughness. On the contrary, if it exceeds 60%, the bubble diameter becomes small,
Further, since the extension of the resin component is reduced, if the foaming is increased, the bubbles may be partially destroyed to generate coarse bubbles. on the other hand,
When the expansion ratio is less than 2 times, the cushioning property of the foam is poor. In addition, the heat insulating property, which is the main characteristic of the foam, decreases, and the flame retardancy, which is the effect of the present invention, also decreases. On the other hand, when it exceeds 50 times, the foam becomes too soft and the cushioning property is lowered.

In the present invention, the degree of crosslinking is a value measured as follows. First, shred the foam to 0.2
g Weigh accurately. Immerse this in 130 ° C. tetralin,
The mixture is heated for 3 hours while stirring and the molten residue is taken out. Then, tetralin is removed from this molten residue using acetone, and further acetone is removed using pure water. The molten residue after washing is dried using a hot air dryer at 120 ° C. and naturally cooled to room temperature. From the weight (W ₁ ) of the residue at that time, the degree of crosslinking can be calculated by the following formula (1).

[0022]

[Equation 1]

The expansion ratio is a value measured as follows. A 10 × 10 cm test piece is cut out from the foam, and its thickness t ₁ (cm) and weight W ₂ (g) are measured. Then, the expansion ratio is determined from the values of t ₁ and W _{2 by} the following equation (2).

[0024]

[Equation 2]

The foam of the present invention, when forcedly combusted,
Melt dripping phenomenon (drip) due to decomposition of resin components does not occur easily, and fire spread is difficult. In addition, the amount of smoke generated is small, and there is little risk of generation of decomposition products that cause environmental pollution. It is considered that the effect of such a foam is realized by the following action. (1) The phosphorus component in the flame retardant promotes carbonization of the foam,
The solidification of combustion residues is promoted and the calorific value of combustion is suppressed. (2) Halogen contained in the flame retardant dilutes a combustible component generated at the time of burning the foam to prevent the foam from spreading.

The foam of the present invention includes, for example, a pipe cover, an air conditioner panel lining material, a heat insulating folded plate which is formed into a mountain shape by bonding with an iron plate, a cushioning material for automobile interior materials, an engine room partition plate, an inorganic fiber mat. It can be used in various fields as a composite product such as a laminated non-combustible backing material for a board, a metal plate, a metal foil, a film, an inorganic fiber or the like.

[0027]

EXAMPLES Examples 1 to 5, Comparative Examples 1 to 5 Compositions for flame-retardant resin foams having the compositions shown in Table 1 (Examples) and Table 2 (Comparative Examples) were prepared and a heat stabilizer was added thereto. As I
0.5 parts by weight of rgnox1010 (manufactured by Ciba Geigy) and 0.3 parts by weight of a carbon block pigment for coloring were added and mixed by a Henschel mixer. This composition was fed to a vented 65 mmφ twin-screw extruder heated to 120 ° C. and extruded from a T-die attached to the extruder to produce a long sheet having a width of 400 mm and a thickness of 2.2 mm.

Next, the obtained long sheet was subjected to a crosslinking / foaming treatment by the crosslinking method and the foaming method shown in Tables 1 and 2. In the case of the electron beam cross-linking method, both sides of the sheet were irradiated with 2.0 Mrad electron beam. In the case of using the chemical crosslinking method, dicumyl peroxide was used as a crosslinking agent. Further, in the foaming method, in the case of the chemical solution foaming method, 2
It heated in order of 10 degreeC-> 220 degreeC-> 225 degreeC. On the other hand, in the case of the vertical hot air foaming method and the case of the horizontal hot air foaming method, 26
It was heated with hot air at 0 ° C.

[0029]

[Table 1]

[0030]

[Table 2]

Evaluation The continuous sheet-shaped flame-retardant resin foams obtained in each of the examples and comparative examples were evaluated as follows. Cellular state The foam was sliced into three equal parts in the thickness direction, and a 10 × 10 cm portion of the sliced surface was observed at 10 locations using a 10 × magnifying glass. Then, when the number of bubbles having a diameter or major axis of 1 mm or more was 5 or less, it was judged as good, and in other cases, it was judged as bad. Flame retardance Evaluation according to UL-94 combustion test method (method A) and MVS
Evaluation was performed according to the S302 combustion test method (method B). U
In the case of the L-94 combustion test method, the quality equivalent to HF-1 was judged to be acceptable. Further, in the case of the MVSS302 combustion test method, a quality equivalent to Class 1 flammability was judged to be acceptable. Moldability A foam molding is formed by a vacuum molding machine equipped with a cup-shaped molding die having a depth (L) with respect to a diameter (D), and the L / D ratio at which the foam can be molded into a cup without breaking. Examined. L
The case where / D was 0.5 or more was regarded as a pass.

The results are shown in Table 3.

[0033]

[Table 3]

[0034]

The composition for flame-retardant resin foam according to the first, second and third inventions contains the above-mentioned flame retardant and polyethylene resin, and the composition ratio thereof is set within a certain range. Therefore, it is possible to form a flame-retardant resin foam which has low smoke generation and hardly generates harmful substances which cause environmental pollution during combustion.

The flame-retardant resin foam according to the fourth aspect of the present invention is formed of the composition for flame-retardant resin foam according to the first aspect of the present invention, and therefore has low smoke emission and causes no environmental pollution during combustion. Less likely to generate harmful substances. According to the method for producing a flame-retardant resin foam according to the fifth invention, the flame-retardant resin foam according to the fourth invention can be efficiently produced.

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Claims (5)

[Claims] 1. A flame-retardant (A) of a halogenated phosphorus-containing compound system containing 50 to 85% by weight of phosphorus and halogen, having a density of 0.910 to 0.930 g / cm ³ and a melt flow rate of 0. A composition for a flame-retardant resin foam, which comprises 5 to 50 g / 10 min of a low-density polyethylene resin (B) and A / B is set to a weight ratio of 0.05 to 0.45. 2. The flame retardant (A) has a melting point of 150 to 25.
The flame-retardant resin foam composition according to claim 1, which has a temperature of 0 ° C. and a particle size of 0.2 to 50 μm. 3. The flame-retardant foam composition according to claim 1, which contains less than 60% by weight of the total resin component of a polyolefin resin different from the low-density polyethylene (B). object. 4. A halogenated phosphorus-containing compound flame retardant (A) containing 50 to 85% by weight of phosphorus and halogen, a density of 0.910 to 0.930 g / cm ³ and a melt flow rate of 0. A low-density polyethylene resin (B) of 5 to 50 g / 10 minutes is included, and A / B is 0.05 to 0.05 by weight ratio.
A flame-retardant resin foam comprising a flame-retardant resin foam composition set to 0.45, having a degree of crosslinking of 15 to 60% and an expansion ratio of 2 to 50. 5. A halogen-containing phosphorus compound-based flame retardant (A) containing 50 to 85% by weight of phosphorus and halogen, having a density of 0.910 to 0.930 g / cm ³ and a melt flow rate of 0. A low-density polyethylene resin (B) of 5 to 50 g / 10 minutes is included, and A / B is 0.05 to 0.05 by weight ratio.
Flame-retardant including a step of molding the composition for flame-retardant resin foam set to 0.45, and a step of heating and crosslinking and foaming the molded composition for flame-retardant resin foam. For producing a flexible resin foam.