DE2150089A1 - Process for the production of butadiene-styrene-methyl methacrylate graft polymers and their use in plastic mixtures containing polyvinyl chloride - Google Patents

Description

KUREHA KAGAKU KOGYO KABUSHIKI KAISHA,
Tokyo, Japan

¹¹ Process for the production of butadiene-styrene-methyl methacrylate graft polymers and their use in plastic mixtures containing polyvinyl chloride "

Priority: October 8, 1970 / Japan, No. 88 694/1970

The invention relates to a process for the production of butadiene-styrene-methyl methacrylate graft polymers with improved Properties which, in particular, have a high level of solvent resistance have and when processed together with polyvinyl chloride such plastic compositions an improved Give impact resistance and increased light transmission »

The process according to the invention for the production of butadiene-styrene-ethyl methacrylate graft polymers is characterized in that in a first process stage a polybutadiene rubber latex or a latex of a butadiene-styrene mixed polymer with a rubber content of 40 to 70 parts by weight, that is greater than 50 percent by weight, based on total latex weight, of particles 0.15 microns in size and above and less than 15 percent by weight, based on the

Total latex weight, containing particles 0.1 microns and below, with 15 to 45 parts by weight of a mixture of monomeric styrene and monomeric! Methyl methacrylate, in which the styrene content predominates, "is treated and that then in a second process stage an additional 11 to 45 parts by weight of monomeric methyl methacrylate are grafted onto the rubber particles in the latex . The invention also relates to the use of the graft polymers obtained in the above manner for the production of polyvinyl chloride containing plastic equipment with improved solvent resistance, in particular in amounts of 5 to 20 parts by weight to 95 to 80 parts by weight of polyvinyl chloride,

In the preparation of the butadiene-styrene-methyl methacrylate graft polymers according to the invention, hereinafter abbreviated as "MBS polymers", the usual conditions of the emulsion polymerization are carried out, the optimum conditions with regard to the Eraulga w tor during the preparation of the rubber latex and during the actual graft polymerization and the catalyst can be used. In addition, polymerization auxiliaries can also be used, for example regulating agents for the degree of polymerization and stabilizing agents for the rubber latex. These auxiliaries can be added at any point during the polymerization reaction. In particular, the transparency of the plastics can be improved by adding a small amount of a crosslinking agent such as divinylbenzene or ethylene glycol dimethacrylate. Such crosslinking agents expediently ground the hoop to be grafted onto the rubber latex

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added nomeren, for example the mixture of monomers! Styrene and monomeric methyl methacrylate. That way lets the quality of the end product improves significantly.

Due to its superior solvent resistance properties, the low gas permeability and the high light permeability, as well as the improvement of the Impact resistance through appropriate reinforcing agents has recently become more and more common for a wide variety of polyvinyl chloride Applications have been used, in particular for packaging for food and as a container for cosmetic Items.

Although containers made from polyvinyl chloride have excellent properties, it has been found that impact resistance is considerably reduced when such containers when filling or pressing in certain container contents be exposed to tensile stress. This reduced impact strength is attributed to so-called stress cracks, i.e. in a special way of cracking.

Although polyvinyl chloride per se is less resistant to such stress cracking is more susceptible than e.g. polystyrene and polymethyl methacrylate, but it has been shown that especially then both A large number of such cracks occur on the surface as well as inside the plastic when the polyvinyl chloride is only exposed to a low tensile stress that does not yet lead to a constriction, and v / when it is in Is immersed in solvents such as methanol, ethanol, acetic acid, edible oils, or soapy water. Such

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215Q089

Stress cracks affect in a remarkable amount of wetness the impact resistance of polyvinyl chloride. The impact or shock resistance of polyvinyl chloride depends on imperfections within the structure of the resin and therefore the occurrence of such stress cracks reduces the mechanical strength of the Polyvinyl chloride is significantly reduced.

The occurrence of such stress cracks at the time the polyvinyl chloride comes into contact with a wide variety of solvents, which are also referred to as active solvents, under an inherently low tensile stress, which does not yet give rise to the known phenomenon of constriction, can also be characterized as stress cracking caused by the environment. Unfortunately, there are not yet many systematic studies and observations of this particular phenomenon. In the given context, however, the work of Haslett and co-workers is of particular interest (SPEJ, 20 (3), 1964). These researchers conducted tests on high-impact polystyrene resin _etc. by butadiene-styrene acrylonitrile resin and reinforced polyvinyl chloride. According to the test results, it has been shown that all of these plastics have a significantly reduced impact strength after treatment with an active solvent, for example mixtures of cottonseed oil and oleic acid in a ratio of 50:50. In fact, serious problems have also arisen in practice from the fact that containers made of polyvinyl chloride filled with edible oil or a cosmetic liquid often break as a result of vibrations during transport.

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The inventors have now carried out further detailed studies on mixtures of polyvinyl chloride and graft polymers from butadiene-styrene-methacrylate line with respect to the occurrence such stress cracks carried out. It has surprisingly been shown that the impairment of the mechanical Strength of the polyvinyl chloride as a result of such stress cracking not only depends on the molecular weight of the Polyvinyl chloride and the type and amount of acidic auxiliaries added during its production, such as stabilizers, Plasticizers and lubricants, depends, but that also the type of graft polymer, v / which per se as a reinforcing agent is added for the purpose of improving the impact strength, has a very significant influence.

Surprisingly, in the course of these investigations shown that when using the graft polymers prepared according to the invention under special conditions for reinforcement of polyvinyl chloride the mechanical strength of the same to a far lesser extent due to the occurrence of by the Environment influenced stress cracks is impaired. The currently commercially available methyl methacrylate-butadiene-styrene graft polymers show with regard to the improvement in impact resistance when used in polyvinyl chloride an excellent effect in itself. But if such a thing modified polyvinyl chloride comes into contact with an active solvent and then only a slight tensile stress if exposed, the impact strength decreases quite considerably, and in some cases this strength drop is so extreme that practically no improvement

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The effect of the graft polymer can be observed more can.

From this fact the new knowledge must be gained, that the retention of the impact strength of polyvinyl chloride to which an HBS graft polymer has been added, under the tensile stress stresses influenced by the environment is practically unrelated to the improvement the impact strength, which under normal conditions

f can be achieved with such graft polymers. Therefore, if a PoDvviny.lchlorid available on the market is mixed with the usual MBS graft polymer, there is practically no difference compared to a polyvinyl chloride, which is produced according to the invention, by means of the usual test methods, which are carried out without the action of an active solvent Has added graft polymer. Under these test conditions, a polyvinyl chloride which contains a graft polymer produced according to the invention may even have a somewhat lower impact strength. If, however, such polyvinyl chloride mixtures are subjected to tensile stress in the presence of an active solvent, the strength properties of the polyvinyl chloride combined with commercially available graft polymer decrease extremely sharply, and in fact the original impact strength improved by this reinforcement can be completely lost under the conditions described. In contrast to this, a polyvinyl chloride which contains an HBS graft polymer prepared according to the invention retains even under such tensile stress conditions.

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gen its excellent properties in terms of impact strength at.

The following Table I shows the results of measurements of the impact strength to determine the brittleness of the relevant Plastic mixtures using the Dynstat method.

Table I.

Type of
sample
body Number of unbroken or partially opened
Test specimen (with a total of 10 samples examined
bodies) j Polyvinyl chloride
with a salary
of 10 ^L / o usual
MBS *) - graft
lymerisat
(Polymerization
degree: 600) Polyvinyl chloride
with a salary
of 10 <fo MBS-
Graft polymer
according to the example
the registration
(Polymerization
degree: 600) A.
B.
C. Polyvinyl chloride
(Polymerization
degree: 600) 10
10
0 10
10
7th I ζ od-
Impact
tenacious
ability 2
(cm-kg / cm 10
10
0 65 58 3
1

*) MBS = methyl methacrylate-butadiene-styrene graft polymer

(1) The test specimen types A, B and C are produced by mixing and Kneading a polyvinyl chloride which contains 5.0 parts by weight calcium zinc stearate as a stabilizer 10 percent of the graft polymer in question for 3 hours at 160 C and then pressing at 195 ° C

2
made into plates under a pressure of 100 kg / cm.

2 7/08 ^ 1

(2) The type A test specimens are produced from the pressed plates without any further changes to the same.

The test specimens of type B are produced according to FIG. 1, i.e., the plate P is placed on a curved surface with a radius of curvature of 7 cm and Leave on the curved surface for 2 hours. Then you take it off.

The test specimens of type C are first produced in the same manner as those of the type B and then 30 micro ψ nutes in an edible oil immersed.

(3) The impact strength is measured as follows: One sets first zv / ei specimens of types A, B and C of 150 mm Length, 2 mm thick and 8 mm wide. These test specimens are then each cut into pieces with a length of 20 mm cut up and every 10 of these specimens are after Dynstat method examined.

Those test specimens which are divided into two. Pieces break, are counted separately, and those specimens / which do not break or are only partially broken, whereby those breaking apart on the impact surface of the pendulum impact device Pieces still related are counted in a separate group. The impact strength of the examined Plastics containing polyvinyl chloride are determined by the number of unbroken or only partially cracked plastics Specimen. In the present pail the broken ones showed Test specimens have a strength of 50 cm kg / cm, while the non-broken or only partially opened test specimens

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body showed a strength of 100 to 120 cm kg / cm.

The Dynstat method used here corresponds to the DIN-IIorm. 53453, using a specimen P with a length of 20 cm, a thickness of 2 mm and a width of 8 mm and this specimen is not notched. The hammer of the pendulum impact device hits the surface in the Manner as shown in FIG.

(4) The measurement of the Izod impact strength is carried out according to the ASTM Standard D-256-56. There are molded bodies made of plates with a thickness of 6 mm used, which according to the process of footnote (1). In this case, however, the plastic mixture contains 15 percent by weight of the relevant MBS graft polymer.

From the numerical values in Table I above, it can be seen that the test specimens of type A, which are made of polyvinyl chloride with a degree of polymerization of 600 and 10 percent by weight MBS graft polymer exist, practically all not broken or just be broken into. In addition, no reduction in impact strength was observed in the case of the type B test specimens. In the case of the test specimens of type C, however, there is a very considerable difference with regard to the measured ones Impact resistance. After being immersed in the active liquid in question, the specimens are namely on the surface A variety of stress cracks were observed when the polyvinyl chloride in question was used alone or with a content of 10 percent a commercially available graft polymer is investigated. The measurement is carried out after the active liquid

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Could act for 30 minutes. Search out of the measurements with the Test specimens can be concluded that in this case the commercially available graft polymer is practically not used for improvement contributes to impact strength. In contrast, the graft polymers prepared using the invention show s test specimens produced that maintain favorable values for impact strength to a remarkable extent, although the Izod impact strength for the "using." the plastic mixtures produced according to the invention is somewhat lower than in the case of the plastic mixtures commercial graft polymer produced plastic mixtures. In spite of the somewhat lower absolute value of the impact strength, the environmental stress cracking is therefore suppressed to a very substantial extent by the graft polymers according to the invention.

Further in-depth studies of this phenomenon have confirmed the above facts and shown that mixtures of polyvinyl chloride and the MBS graft polymers prepared according to the invention under the environmental stress cracking phenomena suffer relatively little and therefore only a slight decrease in the strength properties is observed under these conditions.

From the above investigations by the inventors it follows that that of the measures used in the process according to the invention, the following are of particular importance and therefore represent essential features of the invention:

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- li -

a) The particle size of the diene rubber latex

b) The special conditions during the graft polymerization and

c) The concentration ratio of the monomers to be grafted on with each other during the post-polymerization together with the rubber latex.

The influence of these process parameters is described in detail below explained:

It has been found that the one used for the graft polymerization Rubber latex consist of more than 50 percent particles must be 0.15 microns and larger in size. In addition, the rubber latex must be less than 15 percent by weight of particles whose particle size is 0.1 microns and less.

In the usual production of a butadiene rubber latex or a butadiene-styrene mixed polymer in latex form by means of emulsion polymerization is the mean particle diameter in the range of 0.05 to 0.10 microns. In order to meet the above-mentioned conditions with regard to the particle size, Therefore, such a rubber latex must first be appropriate Wise coagulated or further polymerized, so that one obtains a latex in which more than 50 percent by weight of the latex is made up of rubber particles 0.15 microns or larger in size and less than 15 percent by weight of the latex Particles 0.1 microns and smaller exist. In Table II below, this relationship between the The size of the rubber particles and the oil resistance of polyvinyl

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nyl chloride-containing synthetic resin mixtures shown which MBS graft polyraerisate which have been obtained from rubber latex with different particle sizes.

Table II

Immersion
Time
in the
essba
ren oil,
Min. Number of unbroken or. opened
Test specimen (**) (in a total of 10 examined
Test specimens) 20 wt. - ^c / o der
Latex particles
have a
Size of
0.15 μ and
about that,
50 wt. 5 »ha
ben one
Size of
0.1 μ and
including *) 50 wt .- ^ the
Latex particles
have a
Size of
0.15 μ and
about that,
10 weight yes ha
ben a '·
Size of
0.1 μ and
including *) 80 wt .- ^ of,
Latex particles'
have a
Size of
0.15 μ and
about that,
5 wt. ~ $ Have
a big
of 0.1 μ and
underneath
*) 5
10
30th
60
120 All latex
particles
have a
Big in
Section
0.05 to
0.1 µ
*) 4th
1
0
0
0 10
10
10
8th
5 HHHH
00 OOOO 2
0
0
0
0

(*) The relevant MBS graft polymer is produced as follows been.

On 240 parts by weight of a rubber latex with a rubber content of 60 parts by weight, the rubber component being made up of butadiene in a weight ratio of 70:30 and styrene is a monomer mixture of 13 parts by weight Styrene, which also contains 0.1 part by weight of divinylbenzene, and 7 parts by weight of methy line thacrylate grafted on. 20 parts by weight of methyl methacrylate are then added to the latex modified in this way

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grafted, which contains 0.04 parts by weight of divinylbenzene en.

(**) The determination of the number of unbroken or partially opened Test specimen takes place, v / ie has been described in Pussnote (3) of Table I. In the present pail was however, the immersion time of the specimens in the edible oil varies.

From the numerical values in Table II it can be seen that using a latex made by conventional emulsion polymerization and in which the total latex particles fall in the range of 0.05 to 0.1 microns and also with the latex, v / Whichever contains 20 percent by weight of particles 0.15 and above but 50 percent by weight of 0.1 micron and below particles, a remarkable deterioration in strength properties is observed. In contrast, when using a graft polymer prepared according to the invention ^, at. that the rubber latex contains more than 50 percent by weight of particles 0.15 micron and above and less than 15 percent by weight of 0.1 micron and below particles, the desired high impact strength in. maintained to a remarkable extent.

The further process variable essential to the invention is the actual graft polymerization. This is carried out in two procedural steps in such a way that initially on the A monomer mixture is grafted onto rubber latex, v / elches consists of styrene and methyl methacrylate, but the sty-

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follows

rol makes up the majority. Then / then in a second Process stage a polymerisation with monomers! Methyl methacrylate alone. In this second stage of the procedure the amount of monomer em methyl methacrylate be more than 11 percent by weight, based on the total amount of the produced MBS graft polymer. However, if the amount of monomers Methyl methacrylate in this second process stage is more than 45 percent by weight, then the light transmission suffers and mechanical strength of polyvinyl chloride plastic compounds, to which such a graft polymer is added.

The following Table III explains the relationship between that used in the second process stage in the llachpolymeri sation Amount of monomers! Methyl methacrylate and oil resistance of polyvinyl chloride mixtures to which such graft polymers are added.

Table III

Immersion
time in
edible
Oil, min. Number of unbroken or unbroken
Test specimen (in a total of 10 investigated
Köriiern **) 10 15th 20th 10
30th
60
120 Amount of the up in the second process stage
grafted methyl methacrylate (wt .->) based on
the graft polymer obtained as the end product *) 2
0
0
0 10
10
5
4th 10
10
8th
5 0 O O O O

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(- *) The amount of ^ to be grafted in the second process stage monomeric methyline thacr ylate is accordingly modified or regulated that the weight ratio between styrene and methylniethacrylate in the monomer mixture modifies, which is grafted directly onto the rubber latex in the first process stage. In the present Case is a mixture of 20 parts by weight of styrene and 20 parts by weight of methyl methacrylate to 240 parts by weight a rubber latex with a rubber component of 60 parts by weight grafted on, with 80 percent of the rubber particles having a particle size of 0.15 microns and above and 5 percent have a particle size of 0.1 microns and below. The ratio of Butadiene and styrene in this rubber latex is 70:30.

(. **) The number of non-broken or opened specimens v / is determined in the same manner as described in note (3) to Table I. Also in this pail however, the exposure time of the edible oil is varied.

It can be seen from the numerical values in Table III that the retention of mechanical strength improves quite significantly will if during the second and final stage of the procedure more than 11 percent by weight and in particular more than 15 percent by weight of monomeric methyl methacrylate are grafted on.

The third working variable is also of particular importance, namely the ratio of the rubber component and the component to be grafted on Monomers. In the definition of the invention it is indicated

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denote that 40 to 70 percent by weight of the rubber component "are required. If the proportion of rubber components is less than 40 percent by weight, then it is difficult to obtain a graft polymer with the very good oil resistance desired and then there is also the effect of improving the impact strength of polyvinyl chloride plastic Mixtures not high enough. On the other hand, if the rubber component is more than 70 percent by weight, kick also difficulties, since the Pfropfpolyme- 'risat "agglomerates when this is in powder form from the latex wants to separate, i.e. during the salting out or drying, or such a graft polymer cannot be Work uniformly into the polyvinyl chloride using conventional energy-driven mixers, which in turn includes the impact strength and oil resistance suffer. This fact is explained in more detail in Table IY below.

Table IV

Dive time
in the essba
ren oil, number of
Specimen not broken or unbroken
(in a total of 10 Pro
embody **) 40 50 60 70 Min. Amount of rubber in the graft polymer, weight 10 10 10 5 30th 8th 10 10 2 10 1 6th 6th 7th 2 30th 0 2 3 5 0 60 0 120 0

ffussnote

A monomer mixture of styrene and methyl methacrylate is used

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on a rubber latex made from a butadiene-styrene mixed polymer grafted, which is 75 percent of particles 0.15 microns and above and 5 percent Contains particles 0.1 microns and below in size. The rubber content of the latex is 25 percent and the rubber consists of 70 percent butadiene units and 30 percent of styrene units, the ratio of styrene and methyl methacrylate in the monomer mixture is varied in the following manner depending on the amount of rubber;

Amount of rubber S t / MMA weight / weight ratio

30 wt .- $ 25/25

40 wt. J £ '20/20

50 wt. - $ 15/15

60 wt .- ^ 10/10

70 wt .- ^ '5/5

After completion of the first process stage, 20 parts by weight of monomeric methyl methacrylate are grafted on.

The invention is completed by the following embodiment explained in more detail.

Embodiment

An autoclave of 1 liter capacity is 200 parts by weight a rubber latex with a rubber content of percent, with the rubber made up to 70 percent butadiene consists. 75 percent of the rubber particles are 0.15 microns and above, while only 5 percent of the Particles are 0.10 microns and below in size. In addition, a monomer mixture is fed into the autoclave feeds, which consists of 13 parts by weight of styrene with a content

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of 0.2 part by weight of divinylbenzene and 0.02 part by weight Diisopropylbenzorhydroperoxide and 7 weight parts Fiethyliaethacrylat consists. In addition, 10 parts by weight of distilled water containing 0.01 parts by weight of formaldehyde sulf are used oxylate fed. This polymerization approach is allowed React for 5 hours at a temperature of 60 C. ·

Then 20 parts by weight of monomeric methyl methacrylate are added, which contains 0.2 parts by weight of diisopropylbenzoic hydroperoxide and 0.04 parts by weight of divinylbenzene oil. In this second process stage is carried out long fli ύ polymerization further 7 hours. In this way a latex is obtained with a concentration of the graft polymer of 34 percent,

1.0 part by weight of 2,5-di-tert-isobutyl-paracresol is then used as a stabilizing agent to the latex and then coagulates with the addition of acid. The coagulate is rinsed and dried. In this way, a total of 99 g of a butadiene-styrene-methyl methacrylate profppolymer is obtained.

A polyvinyl chloride with a degree of polymerization of 600, which is 10 percent by weight of the graft polymer prepared above and 5.0 parts by weight calcium or zinc stearate stabilizer contains, will be for 3 minutes at one temperature

kneaded at 160 C. The mixture is then at 195 ⁰ C

2
pressed under a pressure of 100 kg / cm to form sheets.

Test specimens produced from these plates become the following Subjected to tests;

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1) Solvent Resistance Test

The specimens are both in an edible oil and in one on the market at different times Dipped hair oil for gentleman. The test specimens are then cut into pieces 20 mm in length and each 10 of these small bodies are raised using the Dynstat method their impact resistance tested.

The number of unbroken or broken test specimens is determined in the manner described in the note (3) to the table I is described in more detail. The results obtained are summarized below in Tables V and VI:

Table V

Immersion time in edible oil,

Min.

Number of non-broken or opened test specimens (with a total of 10 test specimens examined)

10

Table VI

Dive time in
Hair oil for
Men's,
Mn. Number of not broken or partially cracked
test specimens (with a total of 10 test
th test specimens) Commercially available
Graft polymer IO
20th
30th Graft polymer
according to the invention 5
0
0 10
8th
5

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2) Izod impact strength

The test specimens are 6 mm thick and have a V-notch on. They are to be added with 15 percent by weight of the graft polymer. Polyvinyl chloride has been produced "« The Strength in this impact test is 58 cm-kg / cm.

3) Light permeability or transparency (TP ^c / o) and haze value

(H Iq) ; ;

In the manner described above, ground on a press ^ Plates made with a thickness of 3 mm and then according to the provisions of Japanese Industry Standard JIS-6714 examined for their light transmission and with regard to the haze value. The following results are achieved:

TP Ji. 78.0

H io 6.0

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Claims (2)

Patent claims / (1 /. Process for the preparation of butadiene-styrene-methyl methacrylate graft polymers, characterized in that, in a first process stage, a polybutadiene rubber latex or a latex of a butadiene-styrene mixed polymer with a rubber content of 40 to 70 parts by weight, which is more than 50 Weight percent, "based on total latex weight, of particles 0.15 microns and above and less than 15 percent by weight, based on total latex weight, of particles 0.1 microns and below, 15 to 45 parts by weight a mixture of monomeric styrene and monomeric methyl methacrylate, in which the styrene component predominates, is treated, and that subsequently in a second process stage 11 to 45 parts by weight of monomeric methyl methacrylate are grafted onto the rubber particles in the latex. 2. Use of the graft polymer obtained according to claim 1 for the production of plastic mixtures containing polyvinyl chloride with improved solvent resistance, especially in amounts of 5 to 20 parts by weight per 95 to 80 parts by weight of polyvinyl chloride. 209827/0841 Blank page