JPH0446944A - Flame-retardant resin composition - Google Patents

Abstract

PURPOSE:To prepare the title compsn. excellent in impact strength, heat resistance, and moldability by compounding a specific copolymer of alpha-methylstyrene, a graft copolymer, and a vinyl chloride resin. CONSTITUTION:The title compsn. comprises 15-80pts.wt. copolymer obtd. by copolymerizing alpha-methylstyrene, vinyl cyanide, and a monomer boiling at 150 deg.C or lower and copolymerizable with the two foregoing monomers, 5-40pts.wt. graft copolymer obtd. by graft copolymerizing a monomer mixture shown by the formula onto a rubberlike polymer, and 15-80pts.wt. vinyl chloride resin having a degree of polymn. of 400-800, the sum of the three polymers being 100pts.wt.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a flame-retardant resin composition with excellent impact resistance and heat resistance, and more specifically, a flame-retardant resin composition that has a small amount of residual high-boiling monomer and is free from cyanide. The present invention relates to a flame-retardant resin composition particularly suitable for injection molding, comprising a low molecular weight styrene resin with a low vinyl-rich polymer component and a low polymerization degree vinyl chloride resin.

Styrene-based flame-retardant resins are increasingly being used in various fields because of their excellent balance of heat resistance, impact resistance, and processability.

Among styrene-based resins, ABS-based flame-retardant resin, which is a polymer alloy of vinyl chloride-based resin and ZABS-based resin, has a higher
In particular, it has the characteristics of excellent impact resistance, flame retardance, and appearance of molded products, and recently, these characteristics have been recognized mainly in housings in the 0AIlaH field, and demand has increased significantly.

[Conventional technology and problems]

However, in the field of 0AIl equipment, requirements for molded products are becoming stricter year by year, and in particular, due to the increased internal heat generation and thinner housings associated with the miniaturization of 0AIl equipment, more heat-resistant vinyl chloride/ ABS flame retardant resin is required.

As a method for improving heat resistance, α-
A common method is to use ABS resin using methylstyrene. However, if a large amount of α-methylstyrene is used to increase heat resistance, a considerable amount of α-methylstyrene remains as an unreacted monomer because of its low reactivity. The boiling point of the remaining α-methylstyrene is as high as 163°C.On the other hand, in the case of flame-retardant resins made of vinyl chloride resin/ABS resin, the processing temperature is limited due to the thermal decomposition of the vinyl chloride resin. - Methylstyrene hardly evaporates during processing. Therefore, α-methylstyrene remains in the final molded product and reduces heat deformation resistance, so the purpose of copolymerizing α-methylstyrene to improve heat resistance is sufficient. The problem is that it has not been achieved.

As a method for removing residual α-methylstyrene, AB
How to strip S resin at the end of polymerization and ABS
Although there is a method of drying the powder at high temperature for a long time, it is difficult to adopt it industrially due to efficiency and safety, and the most preferable method is to reduce residual α-methylstyrene in the polymerization recipe.

In order to reduce the amount of residual α-methylstyrene in the polymerization recipe, it is possible to use a large amount of acrylonitrile, which is highly reactive with α-methylstyrene, or to charge the entire amount of α-methylstyrene at the beginning and then add only acrylonitrile continuously. There is. However, with these methods, residual α-methylstyrene is reduced and heat resistance is improved, but a polymer with a high acrylonitrile content is partially produced, and when blended with vinyl chloride resin to make a flame-retardant resin, chloride This has the disadvantage that the compatibility between the vinyl resin and the ABS resin into which α-methylstyrene has been introduced is poor, and the impact strength of the flame-retardant resin is reduced.

[Means for Solving the Problems] In view of the above circumstances, the inventors of the present invention have intensively studied a method for solving the above problems when α-methylstyrene is used. It has been found that heat deformation resistance can be significantly improved by using a copolymer whose polymerization is completed so that the monomer content exceeding C is 2% by weight or less.

Furthermore, vinyl cyanide monomer is 50% of the unreacted monomers from the start of polymerization to the end of polymerization and at the end of polymerization.
It has been found that impact strength can be significantly improved by using a copolymer whose polymerization is completed while keeping the amount below % by weight.

That is, the present invention comprises 15 to 80 parts by weight of the following copolymer (A), 5 to 40 parts by weight of the graft copolymer (B), and 15 to 80 parts by weight of the vinyl chloride resin (C) [(A )+(B
) + (C) = 100 parts by weight].

(A) (a) α-methylstyrene monomer 60-8
5% by weight, (b) 15 to 35% by weight of a vinyl cyanide monomer, (c) 0.5 to 10% by weight of a monomer that can be copolymerized with the above monomers (a) and (b) and has a boiling point of 150°C or less, (d) 0 to 20% by weight of other vinyl monomers copolymerizable with the above monomers (a) and (b) [(a)+(b)+(c)+(d)=100% by weight]
When polymerizing a 7-mer consisting of Until the end of the polymerization and at the end of the polymerization, the unreacted vinyl cyanide monomer is kept in a birch so that the unreacted vinyl monomer is 50% by weight or less. , 0.20-0.50 at 30℃
Copolymer (B) (Bl) rubbery polymer having a range of dl/g from 40 to 90% by weight, (B
8) A graft copolymer obtained by polymerizing 60 to 10% by weight of a monomer mixture, where the monomer mixture has the following formula group; 10≦e+f/4≦40, h=100−e− r-g.

e≧0, f≧0. 0≦g≦90, and 0≦h≦20 [wherein e, f, g and h are respectively vinyl cyanide compound (e), alkyl methacrylate-4 (f),
It shows the weight ratio (%) of the aromatic vinyl compound (g) and other vinyl monomer (h) copolymerizable with these in the monomer mixture.] (C) The degree of polymerization is 400 to 800. Vinyl chloride resin.

The copolymer (A) used in the present invention is (a) α-methylstyrene monomer 60 to 85 ff%, (b) vinyl cyanide monomer 15 to 3511 t%, and (c) copolymerizable with these and having a boiling point. 0.5-1 below 150°C
0% by weight, and (d) 0 to 20% by weight of other vinyl monomers copolymerizable with these [(a) + (b) + (c) + (d
) = 100% by weight), among the unreacted monomers present at the end of polymerization, monomers with a boiling point exceeding 150 ° C, including α-methylstyrene monomer, are 2% by weight or less, and The polymerization is completed by holding the vinyl cyanide monomer in the unreacted monomers from the start of the polymerization to the end of the polymerization and at the end of the polymerization to 50% by weight or less, and the reduced viscosity of the methyl ethyl ketone soluble content is is in the range of 0.20 to 0.50 dl/g at 30°C in dimethylformamide solution.

The amount of α-methylstyrene monomer in (a) is 60 to 85
If it is less than 60% by weight, the heat resistance will decrease;
If it exceeds 5% by weight, the polymerization conversion rate will drop significantly. (b
) The amount of vinyl cyanide monomer is 15 to 35% by weight, and if it is less than 15% by weight, the polymerization conversion rate will decrease significantly;
Moreover, if it exceeds 35% by weight, the heat resistance and impact resistance will be greatly reduced.

The amount of (C) hexamer which can be copolymerized with α-methylstyrene monomer and vinyl cyanide monomer and has a boiling point of 150°C or less is 0.5 to 10% by weight, and less than 0.5% by weight. Heat resistance decreases, and if it exceeds 10% by weight, heat resistance decreases.

Examples of the vinyl cyanide monomer (b) in the copolymer (Δ) include acrylonitrile and methacrylonitrile, which may be used alone or in combination of two or more.

In addition, monomers that can be copolymerized with the α-methylstyrene monomer and vinyl cyanide monomer of (C) and have a boiling point of 150°C or less include styrene (I45°C), methyl acrylate (80°C), and methyl methafrylate. (10
(0°C), ethyl methacrylate (117°C), and isopropyl methacrylate (126°C), which may be used alone or in combination of two or more. Particularly preferred are alkyl (meth)acrylates such as methyl methacrylate.

In addition, other copolymerizable vinyl compounds (d) include:
Examples include butyl acrylate, ethyl acrylate, methacrylic acid, phenylmaleimide, etc., and these may be used alone or in combination of two or more.

The copolymer (A) has a content of 7% by weight or less, preferably 1.8% by weight, of the unreacted monomers present at the end of the polymerization, including α-methylstyrene monomer and having a boiling point of over 150°C. % to complete the polymerization. When the amount of the unreacted monomer exceeds 2% by weight, the heat resistance of the flame retardant resin decreases. As a means for maintaining the monomer amount at 2% by weight or less, for example, 90% by weight or more, preferably 95% by weight or more of the total amount of α-methylstyrene is added to the first stage all at once or continuously, and then, Methods include gradually and continuously adding the remaining monomers.

In addition, the copolymer (A) is maintained such that the amount of vinyl cyanide monomer among unreacted monomers from the start of polymerization to the end of polymerization and at the end of polymerization is 50% by weight or less, preferably 40% by weight or less. to complete the polymerization. If the amount of the unreacted vinyl cyanide monomer exceeds 50% by weight, the impact strength of the flame retardant resin will decrease. As means for maintaining the amount of vinyl cyanide monomer at 50% by weight or less,
Examples include methods such as adjusting the additional composition so that the monomers with a boiling point of 150°C or less, excluding the vinyl cyanide monomer, in the additional components of the monomers in the final stage are not at least 50% by weight, preferably at least 60% by weight. .

The reduced viscosity of the methyl ethyl ketone soluble portion of the copolymer (A) in a dimethyl formamide solution is 0°20 to 0.5.
0 dl/g, and further 0.20 to 0.40 dl/g
If the reduced viscosity is less than 0.20 dl/g, the impact strength will decrease, and if it exceeds 0.50 dl/g, the processability will decrease, which is not preferred.

The graft copolymer (B) used in the present invention is (B1
) A graft copolymer obtained by polymerizing 40 to 90% by weight of a rubber-like polymer with 60 to 10% by weight of a monomer mixture (B). The monomer mixture of (B□) includes (e) 10 to 90% by weight of vinyl cyanide monomer and/or alkyl (meth)acrylate monomer, (f) 10 to 90% by weight of aromatic vinyl monomer, and (g) It consists of 0 to 20% by weight of other vinyl monomers copolymerizable with these.

In the graft copolymer (B), the amount of the rubbery polymer (B1) is 40 to 90% by weight, and impact resistance decreases even if it is less than 40% by weight or exceeds 90% by weight. In the monomer mixture of (aX), vinyl cyanide monomer (e), alkyl methacrylate (f), aromatic vinyl compound (g), and other vinyl monomer copolymerizable with these (h) The weight ratio in the monomer mixture is within the range of the following formula group, and outside this range, impact resistance decreases and is not preferred.

lO≦e + r / 4≦40, h=100-e-f-g.

e≧0, f≧0. 0≦g≦90, and O≦h≦20 [wherein e, f, g, and h are respectively vinyl cyanide compound (e), alkyl methacrylate (f),
The weight ratio (%) of the aromatic vinyl compound (g) and other vinyl monomer (h) copolymerizable therewith in the monomer mixture is shown. ] Examples of the rubbery polymer (B1) in the graft copolymer (B) include polybutadiene rubber and styrene rubber.
Diene rubbers such as butadiene copolymer rubber (SBR), acrylonitrile-butadiene rubber (NBR), acrylic rubbers such as butyl polyacrylate, and polyolefin rubbers such as ethylene-propylene-diene terpolymer rubber (EPDM) Rubber is exemplified, and these may be used alone or in combination of two or more.

As the vinyl cyanide monomer (e) in the Ij monomer mixture (B2), acrylonitrile, methacrylonitrile, etc. are used alone or in a mixture of two or more, and (
As the alkyl (meth)acrylate monomer f), methyl methacrylate, ethyl methacrylate, ethyl acrylate, butyl acrylate, etc. are used alone or in combination of two or more. As the aromatic vinyl monomer (g), styrene, α-methylstyrene, methylstyrene, chlorostyrene, etc. can be used alone or in combination of two or more. Furthermore, as the copolymerizable vinyl monomer (h), acrylic acid, methacrylic acid, phenylmaleimide, etc. can be used alone or in combination of two or more.

For the polymerization of the copolymer (A) and the graft copolymer (B), known polymerization initiators and polymerization degree regulators can be used.
There are no particular restrictions on the type or amount used, however,
The copolymer (A) is polymerized by a monomer division polymerization method in three or more stages, and monomers with a boiling point of 150'C or less, excluding the vinyl cyanide monomer, account for 60% by weight or more in the monomer additional components in the final stage. After the polymerization is completed, the desired powder is obtained by coagulation by a known method.

The vinyl chloride resin (C) used in the present invention has a degree of polymerization of 400 to 800, preferably 400 to 700. If the degree of polymerization is less than 400, the impact strength decreases;
The vinyl chloride resin (C), which is undesirable because it significantly reduces processability if it exceeds 00, includes homopolymers and/or copolymers in which 80% by weight or more is vinyl chloride, and post-chlorinated polyvinyl chloride. It will be done. The copolymer contains a monovinylidene compound such as ethylene, 9-vinyl acetate, methyl methacrylate, butyl acrylate, etc. in an amount of 20% by weight or less as a copolymerization component.

In the flame retardant resin of the present invention, the amount of copolymer (A) is 15
The amount is 80 parts by weight, and if it is less than 15 parts by weight, the heat resistance will decrease, and if it exceeds 80 parts by weight, the flame retardance will decrease, which is not preferable.

The amount of graft copolymer (B) is 5 to 40 parts by weight,
If it is less than 5 parts by weight, impact resistance decreases, and if it exceeds 40 parts by weight, heat resistance decreases, which is not preferable.

The amount of the vinyl chloride resin (C) is from 15 to 80 parts by weight, and if it is less than 15 parts by weight, the flame retardancy will be lowered, and if it exceeds 80 parts by weight, the processability will be lowered, which is not preferred.

The copolymer (A) and the graft copolymer (B) may be blended in a latex state, or after coagulating, they may be used together with vinyl chloride resin, compounding agents, etc. when producing a flame-retardant resin in a powder state. May be blended.

As described above, the present invention provides special copolymers (A), graft copolymers (B), and vinyl chloride copolymers ( C) A flame retardant resin composition is provided.

The flame retardant resin composition of the present invention further contains commonly known antioxidants, heat stabilizers, and lubricants, as well as U.S.
One type or two or more types of V absorbers, pigments, antistatic agents, flame retardants, flame retardant aids, etc. can also be used in combination. Phenolic antioxidants, especially used in styrenic resins,
Phosphite stabilizers, tin stabilizers and lead stabilizers blended with vinyl chloride resins, internal and external lubricants such as various fatty acid esters, metal soaps, and waxes are molded into the flame retardant resin composition of the present invention. It can be used as a resin for higher performance. In the flame retardant resin composition of the present invention, the vinyl chloride resin works effectively and shows good flame retardancy, but depending on the degree of flame retardance required, a small amount of halogen-based N
A flame retardant aid such as a flame agent and an antimony compound can also be blended.

〔Example〕

Hereinafter, the present invention will be specifically explained in more detail based on Examples, but these Examples do not limit the present invention. Shows %.

Examples 1 to 12, Comparative Examples 1 to 22 (a) Synthesis of copolymer (A) The following materials were charged into a reaction vessel equipped with a stirrer and a cooler in a nitrogen stream.

water 25
0 parts Sodium formaldehyde sulfoxylate 0.4
Part ferrous sulfate 0.0025 parts Disodium ethylenediaminetetraacetate 0.01 parts Sodium palmitate 3 parts After heating and stirring at 60°C in a nitrogen stream, first stage of monomers in the proportions shown in Table 1, monomers The second stage of monomers and the third stage of monomers were added dropwise together with cumene hydroperoxide as an initiator and tertiary dodecyl mercaptan as a degree of polymerization regulator at the time shown in Table 1 as follows.

That is, first, the first stage of monomers was added all at once.

Subsequently, a second stage of monomer was continuously added dropwise over a period of 6 hours. Subsequently, a third stage of monomer was continuously added dropwise over 1 hour.

After the dropwise addition, the mixture was further stirred at 60° C. for 1 hour to complete the polymerization.

(B) Synthesis of Graft Copolymer (B) In a nitrogen stream, the following substances and the rubbery polymers shown in Table 2 were charged into a reaction vessel equipped with a stirrer and a cooler.

water 25
0 parts Sodium formaldehyde sulfoxylate 0.2
Part ferrous sulfate 0.0025 parts Disodium ethylenediaminetetraacetate 0. O1 part rubbery polymer After heating and stirring at 60°C in a nitrogen stream in the prescribed amount shown in Table 2, the monomer mixture in the proportions shown in Table 2 and the initiator cumene hydroperoxide were continuously added over 5 hours. After completion of the dropwise addition, stirring was further continued at 60° C. for 1 hour to complete the polymerization.

The copolymer (A) and graft copolymer (B) latexes obtained in (a) and (b) above were mixed uniformly in the proportions shown in Table 4, and a phenolic antioxidant was added. , after coagulating with calcium chloride aqueous solution, washing with water, dehydration, drying,
A powder was obtained by mixing the copolymer (A) and the graft copolymer (B).

(c) Production of flame-retardant resin composition The copolymer (A) and graft copolymer (B) produced as in (a) and (b) above and the vinyl chloride resin shown in Table 3 were mixed into a A tin stabilizer, a lubricant, and a flame retardant aid were further added in the proportions shown in the table and blended using a super mixer, and pellets were produced using a 40-kaku extruder. The tin stabilizer is 2 parts of dibutyltin malate, 1 part of dibutyltin mercapto,
As the lubricant, 1 part of glycerin tristearate and 1 part of polyethylene wax were used, and as the flame retardant aid, 2 parts of antimony trioxide were used.

A test piece was molded from this pellet using a 5-ounce injection molding machine under conditions of a screw rotation speed of 8 Orpm and a nozzle temperature setting of 190°C.

Impact resistance was evaluated by an Izot impact test based on the ASTM (D-648) standard.

Heat resistance is based on ASTM (D-25(i) standard)
B. Evaluation was made at the heat distortion temperature at a load of 6 kg/cd.

Processability was indicated by the flow length of the resin in a mosquito coil-shaped spiral flow mold with a thickness of 3 cm and a width of 10 cm.

Flame retardancy was evaluated based on the tJL-94 standard.

The residual monomer was measured and evaluated using a commercially available gas chromatography method.

The intermediate time of polymerization in Table 1 indicates the intermediate time of the total polymerization time (4 hours for copolymer A-1).

From the results in Table 4, it can be seen that the flame-retardant resin compositions of the present invention represented by Examples are particularly excellent in heat resistance and impact strength, and also have good fluidity and flame retardancy.

(Note) (Rubber-like polymer)...PBd used in latex state
: Polybutadiene rubber, average particle size 2,500 people PBA: Polybutyl acrylate rubber, average particle size 2,400 people (monomer) To N: Acrylonitrile MMA : Methyl methacrylate SL: Styrene αSt: Alpha methyl styrene [Action/Effect] On the ridge As described above, according to the present invention, a flame-retardant resin composition having excellent impact resistance, heat resistance, and processability is provided.

Claims (1)

[Scope of Claims] 1. 15 to 80 parts by weight of the following copolymer (A), 5 to 40 parts by weight of graft copolymer (B), and 15 to 80 parts by weight of vinyl chloride resin (C) [ (A)+(B)+(C)=1
00 parts by weight]; (A) (a) 60-8% by weight of α-methylstyrene monomer, (b) 15-35% by weight of vinyl cyanide monomer, (c ) 0.5 to 10% by weight of a monomer copolymerizable with the above monomers (a) and (b) and having a boiling point of 150°C or less; (d) other vinyl copolymerizable with the above monomers (a) and (b); When polymerizing monomers consisting of 0 to 20% by weight [(a) + (b) + (c) + (d) = 100% by weight], among the unreacted monomers present at the end of polymerization, α-methyl 2% by weight of unreacted monomers with a boiling point exceeding 150°C, including styrene monomers
and the unreacted vinyl cyanide monomer is kept at 50% by weight or less from the start of the polymerization to the end of the polymerization and at the end of the polymerization to complete the polymerization, and the methyl ethyl ketone soluble portion is Reduced viscosity is 0.20-0.50d at 30℃ in dimethylformamide solution
40 to 90% by weight of copolymer (B) (B_1) rubbery polymer in the range of l/g, (
B_2) A graft copolymer obtained by polymerizing 60 to 10% by weight of a monomer mixture, where the monomer mixture has the following formula group; 10≦e+f/4≦40, h=100-e-f- g, e≧0, f≧0, 0≦g≦90, and 0≦h≦20 [However, in the formula, e, f, g and h are vinyl cyanide compound (e), alkyl methacrylate (f ),
The weight ratio (%) of the aromatic vinyl compound (g) and other vinyl monomer (h) copolymerizable therewith in the monomer mixture is shown. ] (C) A vinyl chloride resin having a degree of polymerization of 400 to 800. 2. The copolymer (A) is polymerized by a monomer split polymerization method in three or more stages, and monomers with a boiling point of 150°C or less, excluding vinyl cyanide monomers, account for 60% by weight or more in the monomer additional components in the final stage. The flame retardant resin composition according to claim 1. 3. The flame-retardant resin composition according to claim 1 or 2, wherein the monomer (c) of the copolymer (A) is an alkyl (meth)acrylate.