JPH0341141A - Resin composition - Google Patents

Abstract

PURPOSE:To obtain the title composition excellent in stress relaxation properties and mechanical properties by mixing a specified MBS resin with a vinyl chloride resin. CONSTITUTION:A resin composition comprising an MBS resin having a butadiene content >=50wt.% and a mean particle diameter >=0.2mum and a vinyl chloride resin.

Description

Detailed Description of the Invention A00 Purpose of the Invention (Field of Industrial Application) The present invention relates to a PVC resin composition that has good creep properties at low temperatures and good mechanical properties even at room temperature, and is particularly useful in combination with different materials. We provide resin compositions that have good relaxation properties against internal stresses that occur due to differences in expansion and contraction due to temperature, molding distortion, etc., and external stresses that are constantly applied from the outside. It is widely used as a raw material.

(Prior art) PVC resins, especially hard PVC resins, have poor impact resistance at low temperatures, and have the problem of stress cracking if kept under stress for a long time. be.

In order to improve this point, measures have been taken to improve impact strength by adding MBS resin to PVC resin, but even with this method, if the material is left under stress for a long time, , stress cracking occurs, and in severe cases, the molded product will break apart. Therefore, as a general rule, PVC resin should not be used in areas where stress is applied, or plasticizers should be added to control the creep properties. , the resin was softened and used.

(Problems to be Solved by the Invention) The present invention was made to solve the above-mentioned drawbacks of PVC resin, to relieve stress inside the resin even under constant stress, and to obtain a hard PVC resin composition that does not crack. It is something.

8. Structure of the Invention (Means for Solving the Problems) As a result of intensive study on resin compositions having the above-mentioned functions, the present inventors have found that by using a specific MBS resin, the above-mentioned drawbacks can be eliminated and the constant stress can be reduced. They discovered that even under such conditions, stress can be relaxed inside the resin and a hard PVC resin composition that does not crack can be obtained, and the present invention has been completed.

That is, the present invention provides MB having a butadiene content of 50% by weight or more and an average particle diameter of primary particles of 0.2 μm or more.
The present invention relates to a resin composition characterized by comprising an S resin and a vinyl chloride resin.

The present invention will be explained in detail below.

○MBS resin MBS resin is a copolymer whose main components are methyl methacrylate/rubber (mainly butadiene rubber)/styrene.
It is usually produced by two-stage polymerization in which rubber is graft-polymerized with a monomer mainly composed of methyl methacrylate and styrene. That is, in the first stage polymerization step, a rubber polymer such as butadiene rubber is produced as a nucleating agent, and then styrene or methyl methacrylate, which has good compatibility with arsenic resin, is placed around this nucleating agent to form a core rubber polymer. It is produced by graft polymerization.

*Rubber polymer The most suitable rubber polymer is butadiene rubber.Other rubbers, such as those containing isoprene or chloroprene as main components, have stress relaxation performance at low temperatures of the present invention, but the glass transition point is lower than that of butadiene rubber. It is not preferable for the present invention because it is high.

The butadiene rubber serving as the nucleating agent is preferably a copolymer containing a small amount of monomers other than butadiene so as to facilitate graft polymerization with styrene or methyl methacrylate in the second stage.

Preferred copolymerization components include aromatic vinyl, unsaturated carboxylic acids, alkyl methacrylates, alkyl acrylates, vinyl cyanide, and the like.

On the other hand, if the copolymerization component in the butadiene rubber increases too much, the stress relaxation function of the butadiene rubber at low temperatures will deteriorate, so it is preferable to suppress the proportion of the copolymerization component to 20% by weight or less.

-C, butadiene rubber is produced by an emulsion polymerization method, and polymerization is carried out using an emulsifier, a polymerization modifier, an electrolyte, a polymerization initiator, and the like.

As the emulsifier, alkali metal salts of rosin acids, alkali metal salts of fatty acids, alkali metal salts of aliphatic alcohol sulfuric esters, etc. can be used.

As the electrolyte, alkali metal salts of sulfuric acid, phosphoric acid, hydrochloric acid, and carbonic acid can be used.

As the polymerization regulator, mercaptans, terpenes, halides, etc. can be used as required.

As the polymerization initiator, persulfates, organic hydroperoxides, or redox catalysts using a combination of organic hydroperoxide and a reducing agent can be suitably used.

Polymer production involves bulk polymerization of monomers, continuous addition polymerization,
It can be carried out by generally widely known emulsion polymerization methods such as multistage polymerization.

*Graft-polymerized MBS resin is produced by graft-polymerizing monomers such as styrene and methyl methacrylate that have good compatibility with PVC resin around the rubber polymer of the above-mentioned nucleating agent. As the vinyl monomer, aromatic vinyl and vinyl monomers mainly composed of alkyl methacrylates are preferably used. In particular, styrene as the aromatic vinyl, and methyl methacrylate as the methacrylic acid alkyl ester are preferably used. Polyfunctional monomers may also be used if necessary.

The preferable composition of these monomers to be graft-polymerized is 30 to 70% by weight of styrene, 7% by weight of methyl methacrylate,
Examples include 0 to 30% by weight. If the amount of methyl methacrylate in the monomer is less than 30% by weight, the compatibility with the vinyl chloride resin will deteriorate and it will be difficult to contribute to the improvement of impact strength.If it exceeds 70% by weight, methyl methacrylate The brittle nature of the material becomes more apparent, which may cause a decrease in impact strength.

As a graft copolymerization method, for example, the nucleating agent Go! A preferred method is to first add methyl methacrylate monomer in the presence of the polymer and carry out graft polymerization, and then add styrene and copolymerize.

In the case of ordinary MBS resin, the ratio of the rubber polymer serving as a nucleating agent to the monomer to be grafted is usually 40 to 60% by weight; If the rubber polymer is too large, it will lack compatibility with the PVC resin, and in order to suppress the occurrence of turbidity and fluorescence due to the difference in the refractive index between the rubber polymer composition and the PVC resin, the rubber polymer is made of, for example, butadiene. Since it is a copolymer such as a copolymer of 80:20 and styrene, the amount of butadiene in a typical MBS resin is 50% by weight or less.

The MBS resin used in the present invention has a butadiene content of 50% by weight by adjusting the amount of butadiene rubber polymer serving as a nucleating agent and the butadiene content in the butadiene rubber polymer.
As mentioned above, by using such MBS resin, it becomes possible to relax stress at low temperatures and prevent stress cracking, and the composition itself has good hardness and excellent mechanical strength. This results in a resin composition that has the following properties.

*Preparation of particle size The MBS resin used in the present invention needs to have an average particle size of secondary particles of 0.2 μm or more, and preferably has a particle size of 0.25 to 0.35 μm. belongs to.

Incidentally, secondary particles are particles formed during emulsion polymerization, and these particles are generally supplied as MBS resin powder after being aggregated by salting out or spray drying. When used as a mixture and dispersed in a PVC resin, the MBS resin is dispersed from an agglomerated state into individual particles, and most of the MBS resin exists in the form of primary particles in the PVC resin.

If the average particle diameter of the particles is less than 0.2 μm, it is difficult to maintain the amount of butadiene polymer in the MBS resin at 50% by weight or more, and even if the composition of the butadiene polymer is maintained at 50% by weight or more. Even so, the thickness of the polymer grafted in the second stage becomes thinner, the compatibility with the PVC resin decreases, and impact strength is not developed.

On the other hand, if the particle size is too large, particles will stick together during polymerization and agglomeration will occur, making it impossible to obtain uniform particles. In addition, if a large amount of emulsifier is used to prevent agglomeration, the diameter can be maintained large, but the amount of emulsifier incorporated into the polymer increases, and the emulsifier that cannot be removed even with water washing in the post-process remains in the MBS resin. When blended with resin, the blend may become colored or, in severe cases, may cause thermal decomposition, and the polymerization temperature may need to be raised and the polymerization time may need to be longer than usual, which is economically disadvantageous. So it's not desirable.

The rubber polymer polymerized as a nucleating agent is usually produced as particles of 0.1 μm or less. Therefore, the particle size of MBS resin can be adjusted by adding an acid such as hydrochloric acid or sulfuric acid to the rubber polymer emulsion, or by using these acids together with an electrolyte such as potassium chloride or potassium sulfate to raise the polymerization temperature to 80"C or higher. In general, the larger the amount of acid or electrolyte and the higher the temperature, the larger the particle size can be.

The MBS resin thus obtained is powdered through coagulation, water washing, and drying steps, melt-mixed with a vinyl chloride resin, pelletized, and then molded by conventional methods such as injection and extrusion molding.

○Resin composition The preferred blending ratio of MBS resin and PVC resin in the present invention is 15 to 15 parts by weight of MBS resin per 100 parts by weight of PVC resin.
It is 30 parts by weight.

If the proportion of MBS resin is less than 15 parts by weight, stress cannot be relaxed at low temperatures and stress resin cracking phenomenon cannot be prevented, which is undesirable.On the other hand, if it exceeds 30 parts by weight, the hardness of the composition itself decreases and mechanical This is not preferable because it causes problems such as a decrease in the strength of the target.

The present invention aims to improve the performance of PVC resins, and the PVC resins applicable to the present invention include widely commercially available PVC resins, but the ones that are particularly effective are those with an average degree of polymerization. is a vinyl chloride resin having a value of 600 to 800.

(Function) The resin composition according to the present invention can relieve the internal stress of the resin that occurs when stress is applied in a short time without significantly reducing the electrical and mechanical properties (hardness, strength, etc.) of the PVC resin itself. It is possible to prevent stress cracking of the resin due to stress, which has conventionally been a problem with resin products that are constantly exposed to stress, and exhibits an extremely excellent effect as a coating resin for metal products, for example.

(Example) Examples 1 to 4, Comparative Examples 1 to 2 Production of 0MB5 resin Production of nucleating agent rubber polymer ■ 1.37' height! 95 parts by weight of styrene, 5 parts by weight of styrene,
Potassium stearate 9.5 parts by weight, potassium sulfate 1.
0 parts by weight of potassium persulfate, 1.0 parts by weight of potassium persulfate, and 220 parts by weight of deionized water were charged into an autoclave purged with nitrogen and polymerized at 55°C with stirring at a pressure of 1 g/a1 at a polymerization conversion rate of 90%. Emulsion polymerization was carried out.

■80 parts by weight of 1,3 phthalene, 20 parts by weight of styrene,
Potassium stearate 9.5 parts by weight, potassium sulfate 1.
0 parts by weight, 1.0 parts by weight of potassium persulfate, and 220 parts by weight of deionized water were charged into an autoclave purged with nitrogen, and then polymerized at a pressure of 50 "C15.0 kg/cm" and emulsified with a polymerization conversion rate of 90%. Polymerized.

*Preparation of particles and graft polymerization■) 70 parts by weight of the rubber polymer prepared above as solid content, 0.4 parts by weight of potassium sulfate, and 150 parts by weight of deionized water (including water in the rubber polymer), After raising the internal temperature to 85°C to enlarge the particles, the first stage graft polymerization was carried out by adding a mixture of 0.2 parts by weight of cumene hydroperoxide and 15 parts by weight of methyl methacrylate to formaldehyde sulfoxy A solution of 0.05 parts by weight of sodium chlorate dissolved in 10 parts by weight of deionized water was simultaneously added dropwise continuously over a period of 4 hours from separate supply ports.
Graft copolymerization was carried out under a pressure of 0.2 Kg/cm2 by maintaining stirring for an additional hour.

Next, as a second stage copolymerization, a mixed solution of 0.2 parts by weight of cumene hydroperoxide and 15 parts by weight of styrene and 0.2 parts by weight of sodium formaldehyde sulfoxylate were added.
A solution of 05 parts by weight dissolved in 10 parts by weight of deionized water was
Continuously drip over time and hold for another 1 hour to obtain 0.2 Kg/
Graft copolymerization was carried out under a pressure of "cta".

The average particle diameter of the obtained polymer was 0.28 μm.

Next, 1 part by weight of butylated hydroxytoluene was added, followed by salting out with a 0.5% by weight aqueous sulfuric acid solution.

Subsequently, an aqueous potassium hydroxide solution was added to this salting-out slurry to adjust the pH to 8, and the slurry was separated using a centrifuge, washed with warm water, and dried to obtain an MBS resin as a white powder.

2) 60 parts by weight of the rubber polymer prepared above as a solid content, 0.4 parts by weight of potassium sulfate, and 150 parts by weight of deionized water (including water in the rubber polymer) were heated to bring the internal temperature to 70%. After increasing the temperature to °C to enlarge the particles, as the first stage graft polymerization, a mixture of 0.2 parts by weight of cumene hydroperoxide, 20 parts by weight of methyl methacrylate and 0.05 parts by weight of sodium formaldehyde sulfoxylate was carried out. and a solution prepared by dissolving 10 parts by weight of deionized water were simultaneously added dropwise from separate supply ports over a period of 4 hours,
Graft copolymerization was carried out under a pressure of 0.2 Kg7cm2 by maintaining stirring for an additional hour.

Next, as a second-stage copolymerization, a mixed solution of 0.2 parts by weight of cumene hydroperoxide and a heavy part of styrene 2O and 0.0 parts by weight of sodium formaldehyde sulfoxylate were added.
A solution of 5 parts by weight dissolved in 10 parts by weight of deionized water was continuously added dropwise over 4 hours and held for another 1 hour to yield 0.2 Kg/c.
Dalat copolymerization was carried out under a pressure of m''.

The average particle diameter of the obtained polymer was 0.18 μm.

Next, 1 part by weight of butylated hydroxytoluene was added, followed by salting out with a 0.5% by weight aqueous sulfuric acid solution.

Subsequently, an aqueous potassium hydroxide solution was added to this salting-out slurry to adjust f)H to 8, and the slurry was separated using a centrifuge, washed with warm water, and dried to obtain an MBS resin as a white powder.

3) Add 60 parts by weight of the rubber polymer prepared in step ① above, 0.4 parts by weight of potassium sulfate, and 150 parts by weight of deionized water (including the water content of the rubber polymer), and raise the temperature to bring the internal temperature down. After raising the temperature to 80°C to enlarge the particles, as the first stage graft polymerization, a mixture of 0.2 parts by weight of cumene hydroperoxide and 20 parts by weight of methyl methacrylate and 0.05 parts by weight of sodium formaldehyde sulfoxylate were added. 1 part dissolved in 10 parts by weight of deionized water were simultaneously added dropwise continuously over a period of 4 hours from separate supply ports.
Graft copolymerization was carried out under a pressure of 0.2 Kg/c- by maintaining stirring for an additional hour.

Next, in the second stage of copolymerization, a mixed solution of 0.2 parts by weight of cumene hydroperoxide and 20 parts by weight of styrene and 0.0 parts by weight of sodium formaldehyde sulfoxylate were added.
A solution of 5 parts by weight dissolved in 10 parts by weight of deionized water was continuously added dropwise over 4 hours and held for another 1 hour to yield 0.2 Kg/a.
Dalat copolymerization was carried out under a pressure of m2.

The average particle diameter of the obtained polymer was 0.26 μm.

Next, 1 part by weight of butylated hydroxytoluene was added, and then salting out was performed with a 0.5W aqueous sulfuric acid solution.

Subsequently, an aqueous potassium hydroxide solution was added to this salting-out slurry to adjust the pH to 8, and the slurry was separated using a centrifuge. After washing with warm water and drying, an MBS resin was obtained as a white powder.

○Manufacture of PVC resin/MBS resin composition Three types of MBS resins obtained by the above manufacturing method and polymerization degree of 72
A resin composition was prepared using a vinyl chloride resin of No. 0 (Aron TS-700/manufactured by Toagoi Kagaku Kogyo ■) in the proportions shown in Table 1 and the formulations shown in Table 2.

The resin composition was heated to 120% by heating using a conventional heating stirring mixer.
The mixture was heated and mixed until the temperature increased to 'C' to absorb the additives well, and then cooled to obtain a powdery composition.

Preparation of test pieces for performance evaluation Tensile test pieces and Charpy impact strength measurement test pieces having shapes conforming to JISK-6745 were prepared from the above-mentioned PVC resin/MBS resin composition by injection molding using a conventional method.

The test piece for Rockwell hardness measurement is a 2 mm plate with a diameter of 100 mm, which is also made by injection molding and conforms to JIS-7202.
I created something that complies with the .

○Evaluation method Ruby Measured in accordance with JIS-6745.

Mutual S and Gugu” d4 change Measured in accordance with JIS-7202.

300 dumbbells made in accordance with JIS-6745
Kg/cm2" tensile load was applied to the tensile tester and maintained at -20°C, and the decrease value of the load was shown after 100 hours. (For example, in Example 2, the initial load was 30Q Kg/cm2.
load decreased by 50 Kg/cm” and 250 Kg/cn
+", and this is a resin Mi bottom that is in line with the gist of the invention of a large crosspiece. After applying stress and holding at -20'C for 7 days, the occurrence of cracks in the dumbbells was visually evaluated.

Margin below - C1 Effects of the Invention As is clear from the above, the resin composition obtained by the present invention has excellent stress relaxation performance and moderate surf properties, so It is a useful resin Mi bottom that can be used under usage conditions where stress is constantly applied because it can also relieve stress, thereby preventing cracking of the resin due to stress, and has appropriate opening properties, especially hardness. This effect was not expected from conventional PVC resin/MBS resin compositions, and the synergistic effect of the butadiene content in the MBS resin and the particle size of the MBS resin in the composition improves mechanical properties. It is estimated that the composition was able to exhibit high stress relaxation performance without significantly reducing the stress, and it will be a very useful composition in fields where stress is constantly applied and mechanical strength is required, and it will be effectively utilized in the future. It is something.

Claims (1)

[Claims] 1. A resin composition comprising an MBS resin having a butadiene content of 50% by weight or more and an average particle size of primary particles of 0.2 μm or more and a vinyl chloride resin.