JPS59155410A - Thermoplastic resin and its production - Google Patents

Abstract

PURPOSE:A thermoplastic resin which, when mixed with an ABS resin, can form a resin composition excellent in heat stability and color, prepared by emulsion- polymerizing a monomer mixture containing alpha-methylstyrene and a vinyl cyanide by a specified method. CONSTITUTION:A copolymer is formed by copolymerizing a monomer mixture comprising 50-80wt% alpha-methylstyrene (which may contain a small amount of styrene), 15-35wt% vinyl cyanide monomer (e.g., acrylonitrile), and 0-30wt% different vinyl monomer (e.g., acrylate ester) by a specified method. Namely, 100pts.wt. above monomer mixture is emulsion-polymerized in water in the presence of 0.001-0.3pt.wt. persulfate (e.g., sodium persulfate) and 0.5-5pts.wt. emulsifier (e.g., sodium dodecylbenzenesulfonate). At a conversion of 50-98%, 0.01pt.wt. or more oil-soluble catalyst (e.g., octanoyl peroxide) is added to bring the polymerization reaction to completion.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a heat-resistant thermoplastic resin with excellent thermal stability and improved hue, and a method for producing the same.

Generally, in order to improve the heat resistance of ABS resin, A
A method is known in which a BS resin contains vinyl cyanide and α-methylstyrene as essential components, and if necessary, a copolymer of a copolymerizable vinyl monomer is blended.

Heat-resistant ABS obtained by blending a copolymer that was conventionally polymerized in an aqueous system using a persulfate as a polymerization initiator using a monomer mixture containing α-methylstyrene and vinyl cyanide as main components. The resin composition may have poor hue and may not be stored in a molding machine at a moldable temperature (270'C or higher) for a long time (1
If the solution is allowed to remain in the solution for more than 5 minutes, a significant decrease in hue occurs.

On the other hand, when polymerization is carried out using an oil-soluble catalyst as a polymerization initiator, the reaction progresses slowly and a high molecular weight copolymer cannot be obtained. It is.

As a result of intensive research to solve these drawbacks, the present inventors have developed a monomer mixture containing α-methylstyrene and vinyl cyanide as essential components within a certain composition range by adding persulfate to it. When performing aqueous emulsion polymerization in the presence of ABS, an oil-soluble catalyst is added in the late stage of polymerization to complete the reaction.
It was found that when blended with a resin, a thermoplastic resin with significantly superior thermal stability and hue could be obtained, and the present invention was completed.

That is, according to the pressure of the present invention, first, α-methylstyrene or α-methylsterene containing a small amount of styrene is
80% by weight and vinyl cyanide monomer 15-35% by weight
and 100 parts by weight of a monomer mixture containing 0 to 50% by weight of a vinyl monomer copolymerizable with these, persulfate o, oo
Aqueous emulsion polymerization is carried out in the presence of ~0.3 parts by weight of i and 0.5 to 5 parts by weight of an emulsifier, and further, at the stage of a polymerization rate of 50 to 98%, 10 to 201 parts by weight or more of an oil-soluble catalyst is added to complete the reaction. A method for producing a copolymer (A) is provided. This copolymer is a thermoplastic resin, -
Copolymer (A) 50-900-90% by weight Particle size 0.1-
Butadiene polymer having 0.5 μ or butadiene copolymer containing 50% by weight or more of butadiene 40 to 75
% by weight of a graft copolymer (B) obtained by graft copolymerizing 25 to 60% by weight of a monomer mixture of aromatic vinyl and vinyl cyanide in the presence of 10 to 50% by weight. The plastic resin has significantly better thermal stability and color than conventional AB and S resins.

The monomers used to produce the copolymer (4) will be explained below.

α-Methylstyrene contributes to improving the heat resistance of the copolymer, and in order to obtain sufficient heat resistance, it is necessary to
Must be at least % by weight. However, if the amount exceeds the sox percentage, not only the polymerization rate will be significantly lowered, but also the impact resistance will be lowered. Styrene can be added in several percent by weight in order to improve the polymerization rate and the effect of preventing coloration.

Since it is difficult to polymerize α-methylstyrene alone, vinyl cyanide is added to improve polymerizability.

Vinyl cyanide is required in an amount of 15% by weight or more in the monomer mixture in order to improve the impact resistance of the copolymer. However, if the vinyl cyanide content is more than 35% by weight, the latex becomes somewhat unstable, and the resulting copolymer is likely to be colored and its heat resistance is also reduced.

As the vinyl cyanide, acrylonitrile and methacrylonitrile are preferred, and acrylonitrile is particularly preferred.

Specific examples of vinyl monomers copolymerizable with α-methylstyrene and vinyl cyanide include various known acrylic esters, methacrylic esters, acrylic acid, methacrylic acid, maleimide, N-substituted maleimide, fumaronitrile, and acenaphthylene. One or more types of vinyl monomers may be used.

When polymerizing the copolymer (A), first, a monomer mixture is subjected to aqueous emulsion polymerization in the presence of a persulfate and an emulsifier, and an oil-soluble catalyst is added at a polymerization rate of 50 to 98%. Complete the polymerization reaction.

Representative examples of persulfate polymerization initiators used in the present invention are ammonium persulfate, sodium persulfate, and potassium persulfate. persulfate per 100 parts by weight of the monomer mixture
, o, o i ~0.3 parts by weight are used.

Examples of emulsifiers that can be used include alkali metal salts of alkylbenzenesulfonates such as sodium dodecylbenzenesulfonate and potassium dodecylbenzenesulfonate, and sodium alkylnaphthalenesulfonates. The emulsifier is used in an amount of 0.5 to 5 parts by weight per 100 parts by weight of the monomer mixture.

In the polymerization of copolymer (1), additives such as a molecular weight regulator, an emulsifying agent or a lubricant may be added to the heavy metal system.

In the polymerization of copolymer (A), the oil-soluble catalyst is added at a stage where the polymerization rate is 50 cm or higher.
As an oil-soluble catalyst, l? has an unbranched aliphatic side chain at the α-position. -oxide is preferred, and examples thereof include octanoyl peroxide, decanoyl peroxide, and rauyl zf-oxide. The amount of the oil-soluble catalyst added is 0.01% by weight or more per 100% by weight of the monomer mixture, particularly preferably ldO,01 to 0,3
It is 0 parts by weight.

If the oil-soluble catalyst is added when the polymerization rate has not reached 50%, it will be difficult to complete the polymerization, and if it is added when the polymerization rate has exceeded 98%, it will affect the thermal stability of the polymer. The improvement effect on hue is small.

The oil-soluble catalyst may be added directly or after being emulsified with an emulsifier.

In this way, by adding a small amount of an oil-soluble catalyst to complete the polymerization, a copolymer with significantly improved thermal stability and hue (5
) can be obtained.

The graft copolymer (B) is obtained by graft copolymerizing aromatic vinyl and vinyl cyanide onto a butadiene polymer or a butadiene copolymer containing 50 weight or more of butadiene.

The composition of the graft copolymer (B) is such that the total amount of aromatic vinyl and vinyl cyanide monomers is 25 to 75% by weight of the butadiene polymer or butadiene copolymer.
Weight with 60 weight section. When the total amount of monomers is less than 25% by weight, the compatibility between the rubber component and the resinous component in the graft copolymer decreases, resulting in a decrease in impact resistance.

Furthermore, when the total amount of monomers exceeds 60% by weight, rubber efficiency decreases.

The average particle diameter of the butadiene polymer and butadiene copolymer used to produce the graft copolymer (B) is
Finally obtained copolymer matrix and graft copolymer (B)
affects the physical properties of the blended resin. For example, if the average particle size is less than 0.1 μm, the blend resin cannot exhibit impact resistance, and if it exceeds 0.5 μm, the moldability of the blend resin will be significantly reduced and the gloss of the product will be reduced.

The grafted polymer of the graft copolymer (B) is a butadiene polymer or a butadiene copolymer, and the butadiene copolymer contains 50% by weight or more of butadiene, such as evastyrene-butadiene rubber, Examples include acrylonitrile-butatsuene rubber.

As the vinyl cyanide which is a polymerization component of the graft copolymer (B), acrylonitrile and methacrylonitrile are preferred, and acrylonitrile is particularly preferred.

Aromatic vinyl tosylate, styrene, vinyltoluene, divinylbenzene, and chlorostyrene, which are polymerization components of the graft copolymer (B), are used alone or in combination.

The proportion of the monomer mixture to be grafted onto the butadiene polymer or butadiene copolymer is 65 to 80%
20 to 35% by weight of vinyl cyanide is preferred based on weight. If the vinyl cyanide content is less than 20, the copolymer (A
) and the graft copolymer (B), the impact resistance of the blend resin decreases, and if it exceeds 35% by weight, the polymer emulsion becomes unstable and the polymer becomes more likely to be colored.

The method for producing the graft copolymer (B) usually uses 40 to 75% by weight of phtadiene polymer or butadiene copolymer.
Monophyllar mixture of aromatic vinyl and vinyl cyanide 25
~60 parts by weight are digraft copolymerized by a known method.

A thermoplastic resin made by blending 50 to 90 weight percent of copolymer (A) (10 to 50 weight percent of graft copolymer (B)) has thermal stability, which is a drawback of conventional heat-resistant ABS resins. The blending ratio of the graft copolymer (B) is less than 10 parts by weight, the impact strength of the blended resin is decreased, and when it exceeds 50 parts by weight, the blended resin is Heat resistance deteriorates, and the purpose of the present invention is not met.

Blending may be carried out according to a conventional method. Copolymer N and graft copolymer (B) may be mixed in a latex state, salted out, coagulated, and dried, or each may be salted out, coagulated, and dried individually. You may also blend powders. After these powders are mixed in a screw extruder or the like to form pellets, processing examples are presented. At this time, it may be considered to add stabilizers and processing aids.

The blended resin of the present invention is a resin composition with excellent heat resistance, impact resistance, and moldability, and its industrial utility value is extremely high, and it is widely used as a high-performance resin in home appliances, It has applications in automobile interior parts.

1. Manufacturing Example 1 of Copolymer (1) The substances shown in Table 1 were charged into a 11 glass autoclave equipped with a stirrer while blowing in nitrogen gas. After raising the temperature to 65°C, a 10% aqueous solution of potassium persulfate was added to initiate polymerization, and 4 hours after the start of polymerization, 0.15% of lauryl peroxide was added. p was added. The polymerization rate at this point was 63%. - The reaction was continued for a further 6 hours. The final polymerization rate was 99%.

Comparative Example 1 The same operation as in Example 1 was performed except that 4 hours after the start of polymerization, lauryl 4-oxide was not added and 75 ml of a 1% potassium persulfate aqueous solution was added.

Example 2 The same operation as in Example I was carried out except that lauryl peroxide was not added 4 hours after the start of polymerization, but was added 8 hours after the start of polymerization. The polymerization rate at this point was 98%.

Comparative Example 2 The same operation as in Example 1 was performed except that lauryl/('-oxide was not added 4 hours after the start of polymerization, but was added 3 hours after the start of polymerization.

The polymerization rate at this point was 45%. Although the reaction was continued for a further 6 hours, the polymerization rate did not progress beyond 92%.

Example 3 The same procedure as in Example IK was carried out except that the same amount of octanoyl peroxide was used in place of the lauryl peroxide used in Example IK.

Example 4 The same procedure as in Example 1 was carried out except that the same amount of t-butylno-9-oxyneodecanoate was used in place of the lauryl peroxide used in Example 1.

Example 5 The same operation as in Example 1 was carried out except that the same amount of benzoyl peroxide was used in place of the lauryl peroxide used in Example 1.

2. Production of graft copolymer (B) Into the reaction vessel in which copolymer (A) was produced, add 50%
The temperature was raised to ℃. When the internal temperature reached 50°C, continuous charging of the monomer mixture shown in Table 2 was started, and the charging was completed in 5 hours.

Table 2 After charging the above monomer mixture, the internal temperature of the reaction vessel was set to 7.
The temperature was raised to 0°C, and the polymerization reaction was continued for an additional 2 hours to complete the polymerization.

3. Blend of copolymer (4) and graft copolymer (B) 70 parts of the copolymer (A) produced in 1 above and the graft copolymer (B) produced in 2 were mixed in a latex state. An antioxidant was added to this mixture, and the mixture was precipitated, dehydrated, and dried in a conventional manner to obtain a powder. The obtained powder was cross-melted in an extruder to form belenium.

Thermal stability was evaluated by the following method.

That is, resin was allowed to stay in the cylinder of a 2-ounce injection molding machine with a cylinder temperature of 270°C for 15 minutes, and then injection molded.
Yellowness of 0x3mm plate YI! Measure s. Further, the yellowness YIO of a molded product injected without performing a residence operation using an injection molding machine under the same conditions is measured.

The change in yellowness (fit DYI-Y115 YIO) was determined and used as an index for evaluating the thermal stability of the resin. Yellow is the color and color made by Nippon Heavy Industries Co., Ltd.
difference meter model -1
Measured using 01DC. The results are shown in Table 3.

Claims (1)

[Claims] 1. 50 to 80% by weight of α-methylstyrene or α-methylstyrene containing a small amount of styrene, 15 to 35% by weight of vinyl cyanide monomer, and a vinyl monomer copolymerizable with these. Monomer mixture 100 containing 0 to 50 parts by weight
Part by weight is subjected to aqueous emulsion polymerization in the presence of 0.001 to 0.3 parts by weight of a persulfate and 0.5 to 5 parts by weight of an emulsifier, and further,
At the stage where the polymerization rate is 50-98%, oil-soluble catalyst 4! o, o1
A method for producing a thermoplastic resin, which comprises adding at least part by weight to complete the reaction. 2. 50 to 80% by weight of α-methylstyrene or α-methylstyrene containing a small amount of styrene, 15 to 35% by weight of vinyl cyanide monomer, and 0 to 30% by weight of vinyl monomer copolymerizable with these. Monomer mixture containing 100
Part by weight is subjected to aqueous emulsion polymerization in the presence of 0.001 to 0.3 parts by weight of a persulfate and 0.5 to 5 parts by weight of an emulsifier, and further, at a stage of a polymerization rate of 50 to 98 inches, an oil-soluble catalyst is added. 01
Copolymer obtained by adding more than part by weight and completing the reaction■
'aromatic vinyl and A method for producing a thermoplastic resin, which comprises blending 25 to 605 to 60 parts by weight of a vinyl cyanide monomer mixture and 10 to 50 parts by weight of a graft copolymer (B) obtained by copolymerizing. 3. 50-80% by weight of α-methylstyrene or α-methylstyrene containing a small amount of styrene, 15-35% by weight of vinyl cyanide monomer, and 0-50 parts by weight of vinyl monomer copolymerizable with these. A monomer mixture containing 10
0 parts by weight was subjected to aqueous emulsion polymerization in the presence of 0.001 to 0.3 parts by weight of persulfate and 0.5 to 5 parts by weight of emulsifier, and further, at the stage of a polymerization rate of 50% or more, an oil-soluble catalyst, lo, o1 Copolymer (A) obtained by adding at least part by weight and completing the reaction
Aromatic vinyl and cyanide are added in the presence of a butadiene polymer or butadiene copolymer containing 50 to 50% by weight or more of butadiene having a grain size of 50 to 90% by weight and an average particle size of O51 to 0.5μ. Vinyl monomer mixture 2
A thermoplastic resin which is obtained by graft copolymerizing 5 to 60% by weight and blending 10 to 50% by weight of a graft copolymer (B).