JPH0791407B2 - Method for producing flame-retardant expandable resin particles - Google Patents

Description

TECHNICAL FIELD The present invention relates to flame-retardant expandable resin particles. In particular,
It is used for producing a metal-foam resin laminate.

(B) Conventional Technology Conventionally, expandable resin particles made of a styrene-maleic anhydride copolymer are pre-expanded, and the pre-expanded particles are filled in a mold in which a metal body for lamination is previously placed and heated. There is known a method for producing a metal-foam resin laminate in which foamed resin particles are fused on the surface of the metal body for lamination to form a laminate (Japanese Patent Laid-Open No. 62-46343). Also,
As a method for producing the expandable resin particles, while suspending styrene-maleic anhydride copolymer resin particles in an aqueous medium, the maleic anhydride group is subjected to a reaction with a compound containing an active hydroxy group. Before the reaction, during the reaction or after the reaction, a method for producing expandable resin particles is known in which the resin particles are impregnated with a volatile foaming agent (Japanese Patent Publication No. 60-49217). .

(C) Problem to be Solved by the Invention The metal-foam resin laminate produced by the above method is composed of a foam resin layer having relatively high heat resistance. From the viewpoint of responding, higher flame retardancy is required. However, the flame-retardant expandable resin particles obtained by adding a flame retardant that is usually used to the expandable resin particles described above have a problem that the metal adhesion is extremely lowered.

The present invention has been made to solve the above problems, and an object of the present invention is to provide a method for producing flame-retardant expandable resin particles having good metal adhesion and excellent flame retardancy.

(D) Means for Solving the Problems According to the present invention, styrene-maleic anhydride copolymerized synthetic resin particles are suspended in an aqueous medium, with respect to the maleic anhydride groups, 2.5 to 150 mol%. Adhesion to metal by subjecting to reaction with a compound containing 2 to 4 active hydroxy groups and impregnating the resin particles with a volatile foaming agent and bromophenylallyl ether during or after the reaction. A flame-retardant expandable resin particle-producing method is provided. As the resin used in the present invention, maleic anhydride is 2 to
Styrene containing 25% by weight and having an average degree of polymerization of 500 to 4000
Maleic anhydride copolymer resin is preferred. The resin pellets are obtained, for example, by pelletizing a commercially available styrene-maleic anhydride copolymer with an extruder or the like.

When the content of maleic anhydride in the resin is 2% by weight or less, the heat resistance is not excellent and the adhesion with metal becomes insufficient.
Further, if it exceeds 25% by weight, impregnation of the foaming agent will be difficult. Further, when the average degree of polymerization of the resin is 500 or less, blocking occurs during impregnation of the foaming agent, and heat resistance becomes poor, and when it is 4000 or more, brittleness increases, which is not preferable as a foam-forming body.

Even more preferred as the copolymer resin particles of the present invention are those having a maleic anhydride content of 5 to 15% by weight and an average degree of polymerization of 900 to 2000.

In producing expandable resin particles using the styrene-maleic anhydride copolymer resin particles, the copolymer resin particles are usually suspended in an aqueous medium.

The aqueous medium consists of water and a suitable amount of dispersant. As the dispersant, partially saponified polyvinyl alcohol, polyacrylic acid salt, polyvinylpyrrolidone, carboxymethylcellulose, methylcellulose, calcium stearate, other organic compounds such as ethylene bis-stearamide, calcium pyrophosphate, calcium phosphate, calcium carbonate, carbonic acid. Inorganic compounds such as magnesium, magnesium phosphate, magnesium pyrophosphate, and magnesium oxide, which are fine powders which are hardly soluble in water, are used. In the present invention, when an inorganic compound is used as the dispersant, it is preferable to use a surfactant such as sodium dodecylbenzenesulfonate together. These dispersants are generally used by adding 0.01 to 5% by weight to water.

In the present invention, "a compound having at least two active hydroxy groups" (hereinafter referred to as a hydroxy compound) has two or more hydroxy groups capable of reacting with the maleic anhydride group of the styrene-maleic anhydride copolymer resin. Means a compound.

It is particularly preferred that the number of active hydroxy groups is 2. As the compound having two active hydroxy groups,
Examples thereof include an aliphatic dioxy compound, an aromatic dioxy compound, an aromatic dioxy compound containing an aromatic ring, and an aliphatic diethanolamide. This will be described in more detail below.

(1) Aliphatic dioxy compound: Here, the aliphatic residue includes various structures such as a structure containing a saturated or unsaturated linear, branched, cyclic or alicyclic residue. Specific examples include the following compounds.

(A) the general formula HO- (CH ₂₎ compounds wherein n 2-10 in -NOH, such as ethylene glycol, propylene glycol, and the like.

(B) In the general formula H- (OR) -nOH, n is 2 to 6
And compounds in which R is an alkene group, such as diethylene glycol, dipropylene glycol, tetraethylene glycol, tetrapropylene glycol and the like.

(C) In addition to the above, compounds represented by the following formulas can also be used.

(II) Aromatic dioxy compound (a) Polyhydric phenols: hydroquinone, disorcin,
Examples include catechol and lower alkyl- or chloro-substituted derivatives thereof, pyrogallol-1-methyl ether, pyrogallol-2-methyl ether and the like, and compounds having two hydroxy groups in the aromatic nucleus or substituted aromatic nucleus.

(B) a compound represented by the following general formula: In the formula, -R- is> CH ₂ ,> CHCH ₃ , -S-, -SO-, , X, Y, X ′, Y ′ are the same or different and are hydrogen atoms,
It means a halogen atom, a lower alkyl group or the like. Particularly preferred among this group of compounds is bisphenol A [2,
2-bis (4'-hydroxyphenyl) propane].

(III) an aliphatic dioxy compounds containing an aromatic ring: Examples of the compounds belonging to this range Chiyuu, for example the general formula HO- (CH ₂₎ -nR '- in (CH ₂₎ n in -nOH is 1 or 2, R 'Is a group such as: And a compound that is

(IV) Fatty acid diethanolamide: Here, the aliphatic residue of the fatty acid includes various structures such as a structure containing a linear, branched, cyclic or alicyclic residue. Further, in this case, the fatty acid may be a mixed fatty acid of various fatty acids having different numbers of carbon atoms. A preferred specific example is coconut oil fatty acid diethanolamide. Examples of the compound having 3 or more active hydroxy groups include glycerin and pentaerythritol.

The hydroxy compound is added in an amount of 2.5 mol% or more based on the total amount of maleic anhydride groups of the styrene-maleic anhydride copolymer resin. Generally, it may be added in an amount of up to 150%. With the addition amount less than 2.5 mol%,
If the pre-expanded particles from the obtained expandable particles are not overfilled, a good foam-formed product cannot be obtained, and the object of the invention cannot be achieved. Also, the use of a large excess of the hydroxy compound with respect to the content of the anhydrous substance will be meaningless from an economical or technical point of view. The reaction of the styrene-maleic anhydride copolymer resin particles with the hydroxy compound is carried out at a temperature of 80 ° C to 150 ° C, preferably 90 ° C to 110 ° C.
It is carried out by heating and stirring (depending on the reaction temperature and the size of the copolymer particles) for 3 to 60 hours.

It is considered that the hydroxy group of the hydroxy compound attacks the acid anhydride group in the molecular chain of the styrene-maleic anhydride copolymer to open the ring and form a half-ester bond. At this time, it is considered that the two hydroxy groups of the hydroxy compound react with the acid anhydride groups of different copolymers to form a half-ester bond and a kind of crosslinked structure. It is considered that, when the foaming agent is impregnated into the pre-expanded particles, the secondary foaming power is increased, and various effects such as the heat shrinkage ratio of the obtained foamed molded product can be reduced are exhibited. To be

Impregnation of the particles of the styrene-maleic anhydride copolymer resin with the volatile foaming agent and bromophenylallyl ether may be carried out during or after the reaction. However, it is most preferable in industrial practice to add the hydroxy compound, the volatile blowing agent and bromophenylallyl ether to the same reaction system, and carry out the esterification reaction and the impregnation of the blowing agent in the same treatment.

Examples of the volatile foaming agent in the present invention include aliphatic hydrocarbons such as propane, n-butane, i-butane, n-pentane, i-pentane and n-hexane, and cycloaliphatic hydrocarbons such as cyclopentane and cyclohexane. Examples thereof include halogenated hydrocarbons such as hydrogen, methyl chloride, ethyl chloride, dichlorodifluoromethane, chlorodifluoromethane and trichlorofluoromethane. Of these blowing agents, it is preferred to use propane or n-butane and mixtures thereof. These foaming agents are generally used in a proportion of 3 to 40% by weight based on the polymer resin particles.

Examples of the bromophenyl allyl ether in the present invention include 2,4,6-tribromophenyl allyl ether. Tetrabromobisphenol A (or S) allyl ether Pentabromophenyl allyl ether Etc. can be mentioned. The impregnation amount of this bromophenylallyl ether can be usually 0.5 to 5.0 parts by weight, preferably 1.5 to 3.0 parts by weight, based on 100 parts by weight of the styrene-maleic anhydride copolymer resin particles. If it exceeds 5.0 parts by weight, the metal adhesive is extremely deteriorated, which is not preferable. If it is less than 0.5 part by weight, the flame retardancy becomes insufficient, which is not preferable.

In the present invention, it is preferable that a solvent that dissolves the styrene-maleic anhydride copolymer resin particles is present when the foaming agent and bromophenylallyl ether are added. This solvent is preferably previously stirred and dispersed in an aqueous suspension, for example, so that the styrene-maleic anhydride copolymer resin particles are sufficiently impregnated.

Such solvents include aromatic hydrocarbons such as benzene, toluene, xylene and ethylbenzene, esters such as methyl acetate and ethyl acetate, halogenated hydrocarbons such as dichloroethane, trichloroethane, tetrachloroethane, trichloroethylene and tetrachloroethylene, sillohexane and cycloheptane. And cyclic hydrocarbons such as n-hexane and n-heptane.

The base resin of the expandable resin particles of the present invention may contain various additives such as a filler, a plasticizer, a lubricant, a colorant, an ultraviolet absorber and an antioxidant.

To manufacture a flame-retardant metal-foamed resin laminate having good adhesion to the laminating metal body by filling the pre-foamed resin particles in a mold in which the laminating metal body is arranged in advance and performing heat molding. You can The above-mentioned metal is, for example, aluminum, iron, stainless steel, copper, nickel or zinc-iron.

(E) Action The bromophenyl allyl ether contained in the flame-retardant foamable resin makes the foamable resin flame-retardant without lowering the adhesiveness to metal.

(F) Example Example 1 (simultaneous gas impregnation in the reaction) In an autoclave having an internal volume of 5, 2800 g of water, 12.4 g of metathesis magnesium pyrophosphate, 0.4 g of sodium dodecylbenzenesulfonate were added, and then styrene-
1600 g of particles of maleic anhydride copolymer [trade name Dailark 232 (manufactured by Arco Polise, USA) in which the content of maleic anhydride as a copolymerization component is 8.0% by weight average degree of polymerization: 1200;] After turbidity, 8 g of 1,4 butanediol, 64 g of toluene, 24 g of tribromophenyl allyl ether (trade name: Piroguard FR100, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.), and 4 g of dicumyl peroxide were added. Then, 176 g of butane as a foaming agent was press-fitted while stirring in a closed state. Then 100
The temperature was raised to ℃ and maintained at this temperature for 7 hours. After 30
After cooling to 0 ° C., the expandable particles impregnated with the foaming agent were taken out. The particles were washed, dehydrated and dried, then placed in a closed container and kept at a temperature of 15 ° C. for 72 hours to produce flame-retardant expandable resin particles. If you heat these particles with steam at 98 ℃ for 5 minutes,
Pre-expanded particles having a bulk specific gravity of 0.015 were obtained. The bulk specific gravity of the pre-expanded particles was adjusted to 0.033, the pre-expanded particles of 3000 CC were filled in a mold with a depth of 25 mm and an internal volume of 3000 cc, and 1.0 kg / cm ² (gauge pressure) of steam was applied for 40 seconds. When heated and foam-molded, a good foam-molded product with 90% fusion bonding was obtained.

The foamed molded product obtained here was annealed at 50 ° C for 24 hours and then left in an oven at 90 ° C for 7 days to give 2.5%.
Showed shrinkage of. In addition, infrared analysis of this foamed molded product revealed an absorption peak based on an ester bond. Further, when the expandable particles were dipped in toluene, a swollen insoluble material (about 15 W / W% of the expandable particles) which was close to a spherical shape remained. This insoluble material is considered to be a product of cross-linking. On the other hand, the average degree of polymerization of the toluene-dissolved component was 1500.
If the flame retardancy of the obtained foam is measured by the JIS A-9511 method,
It was 1.1 seconds, and the foam had sufficient flame retardancy.

Adjust the bulk specific gravity of the pre-expanded particles to 0.033, 300 at a depth of 25 mm
Put a 300 × 400 × 0.3t iron plate in a × 400 mold, fill 3200cc of pre-expanded particles on it, and place a 300 × 400 × 0.3t iron plate on the pre-expanded particles, 1.0kg / Foaming was performed by heating with steam of cm ² (gauge pressure) for 40 seconds. The metal-adhesive strength of the obtained metal-foam integrated product was measured and found to be 1.2 kg / cm ² .

Example 2 (Gas impregnation after reaction) In an autoclave having an internal volume of 5, 2800 g of water, 12.4 g of pyrolysis magnesium pyrophosphate, 0.4 g of sodium dodecylbenzenesulfonate were added, and then styrene-
1600 g of particles of a maleic anhydride copolymer [trade name Dailark 232 (manufactured by Arco Polymers, Inc., USA) having a content of maleic anhydride as a copolymerization component of 8.0% by weight and an average degree of polymerization of 1200] were added and suspended. After that, 8 g of 1,4-butanediol,
64 g of toluene, 24 g of tripromophenyl allyl ether (trade name: FR100), and 4 g of decyl peroxide were added. Then, the temperature was raised to 100 ° C. with stirring, and this temperature was maintained for 7 hours. Then, it cooled to 30 degreeC. (Some particles were taken out and the particles were immersed in toluene for 24 hours. As a result, a spherical swollen insoluble matter remained.) After that, 176 g of butane was pressed in in a sealed state. Then 100 ° C
The temperature was raised to and maintained at this temperature for 4 hours. After 30
The expandable particles impregnated with the foaming agent were taken out by cooling to ° C. The expandable particles obtained here showed the same expandability, moldability, flame retardancy and metal adhesion as the expandable particles obtained in Example 1.

Example 3 In Example 1, tribromophenyl allyl ether
Instead of using 24 g (1.5 parts by weight per 100 parts by weight of styrene-maleic anhydride copolymer particles), as shown in Table 1, tribromophenyl allyl ether, tetrabromobisphenol A allyl ether (trade name: Fire Guard 3200, manufactured by Teijin Chemicals Ltd.), 0.4 to 5.5 parts by weight of tetrabromobisphenol S allyl ether or pentabromophenyl allyl ether, and otherwise the same as in Example 1 to produce flame-retardant expandable resin particles.

Further, using the flame-retardant expandable resin particles, pre-expanded particles were prepared in the same manner as in Example 1 and then a foamed molded product was prepared, and the flame retardancy and the metal adhesive strength were measured. As a result, as shown in Table 1, both flame retardants were 1.5 and 3.0.
It was confirmed that the addition of parts by weight exhibits excellent flame retardancy while maintaining high metal adhesion strength.

Example 4 Molding was performed under the same conditions as in Example 1 except that another metal was used instead of the iron plate placed in the molding machine, and the metal adhesion strength of the obtained metal-foam integrated product was measured. The results are shown in the table below.

Comparative Example 1 Instead of tribromophenyl allyl ether, 0.4 to 5.5 parts by weight of known flame retardants (chlorinated paraffin, perchlorocyclopentadecane, tricresyl phosphate, trioctyl phosphate, cresyl phenyl phosphate and hexabromobenzene). Was used to produce flame-retardant expandable resin particles in the same manner as in Example 1 to prepare a foam molded article, and its flame retardancy and metal adhesive strength were measured. The results are shown in Table 3.

Comparing Table 3 above with Table 1 on page 20, when tribromophenyl allyl ether is used, both flame retardancy and metal adhesion strength are excellent, while conventional flame retardants are used. If the value is about 1.0Kg / cm
Below, the metal adhesive strength is considerably reduced.

In Table 3, the metal adhesion strength is 1.0 when the amount of cresyl phenyl phosphate is 3.0 parts by weight.
Some of them exceed Kg / cm, but in that case, the flame retardancy is inferior to the case where the same amount of tribromophenylallyl ether is used.

Therefore, it can be seen from the results of Tables 1 and 3 that the tribromophenyl allyl ether has an excellent effect of preventing a decrease in metal adhesion strength as compared with other known flame retardants.

(G) Effect of the Invention According to the present invention, it is possible to provide a method for producing a flame-retardant expandable resin particle capable of producing a foam-molded pair to which flame retardancy is imparted without lowering adhesion with a metal. it can. When the flame-retardant expandable resin particles are formed by filling the pre-expanded particles in a mold, it is possible to obtain a foam-molded article having a low specific gravity without overfilling. Further, the foamed molded product obtained at that time has a characteristic that shrinkage due to heat is very small even when it is left at a high temperature.

Claims (2)

[Claims] 1. A compound containing styrene-maleic anhydride copolymer resin particles suspended in an aqueous medium and containing 2.5 to 150 mol% of 2 to 4 active hydroxy groups based on the maleic anhydride groups. In addition to the reaction with the above-mentioned reaction, by impregnating the resin particles with a volatile foaming agent and bromophenylallyl ether during or after the reaction, it is possible to obtain flame-retardant foamable particles having adhesiveness with a metal. A method for producing flame-retardant expandable resin particles, which is characterized. 2. Bromophenyl allyl ether is 2,4,6
-The process according to claim 1, which is tribromophenyl allyl ether, tetrabromobisphenol A (or S) allyl ether or pentabromophenyl allyl ether.