NO164215B - METHOD AND HAIR COLOR FOR DYING HER. - Google Patents

Description

Method of making a

copolymer consisting of butadiene-styrene-methyl methacrylate.

The present invention relates to a method for producing a copolymer consisting of butadiene-styrene-methyl methacrylate, to be mixed into polyvinyl chloride or polyvinylidene chloride in order to improve its properties, such as transparency, impact strength, bending properties, etc. Such graft copolymers are hereinafter referred to as "MBS- resins".

So-called graft copolymers are well known which are produced by post-polymerization (consecutive polymerization, hereinafter referred to simply as polymerization) of vinyl monomers such as styrene, acrylonitrile or methyl methacrylate either individually or as a mixture of several of these as follows that a rubber-like latex is produced.

These graft copolymers have excellent mechanical strength and have therefore been used alone for various shaped objects. They have also been mixed with other resins, such as polyvinyl chlorides, to increase the impact strength of shaped articles thereof.

However, many graft copolymers which have been produced according to previously known methods have the disadvantage that they lead to less transparent and poorly weather-resistant products, even though they

are able to improve the impact strength of polyvinyl chlorides with which they are mixed and crushed. Resin compositions containing acrylonitrile also have the disadvantage that they are not weather resistant.

From British patent document 830,785, a graft copolymer is known which is produced by graft polymerization of vinyl monomers whose main component is methyl methacrylate on butadiene-styrene copolymer latices, whereby the content of! styrene-butadiene is kept relatively low. The polymers themselves according to the aforementioned patent document are used as impact-resistant resins,

British patent document 840,153 relates to the composition obtained by mixing graft copolymers produced by grafting styrene monomer and a rubber component of butadiene styrene. The purpose of the composition is to improve the impact strength of a polymer resin of styrene or with styrene as the main component.

The purpose of the present invention is to specify a method for producing a copolymer which, when added to polyvinyl chloride or polyvinylidene chloride, improves its properties, such as transparency, impact strength, bending properties, etc.

The invention is characterized by; that an elastomer latex is first formed by copolymerizing jbutadiene and styrene, where butadiene preferably constitutes at least 60% by weight, in the presence of 0.05 - 5% by weight of a copolymerizable crosslinking agent consisting of dimethacrylate or divinylbenzene, and that then 40-75 parts by weight of to this elastomer is added 25 - 60 parts by weight of a mixture of styrene and methyl methacrylate containing 0.01 - 5 parts by weight of the above-mentioned cross-linking agent, after which it is stirred and heated to form a graft copolymer, and then cooled, and then, optionally after the addition of further methyl methacrylate acrylate, is reheated to polymerize further.

The MBS resin according to the invention can be assumed to work in the following way. When the MBS resin is mixed and crushed with a polyvinyl chloride, rubber component particles of constant size are dispersed in the polyvinyl chloride in such a way that they are protected by the surrounding layers against layers of styrene methyl methacrylate resin and methyl methacrylate resin. The styrene-methyl methacrylate layer and the rubber component thereby have a high mutual solubility, while the methyl methacrylate layer has a high mutual solubility towards the polyvinyl chloride. Since the cross-linking takes place by particle bonds, the adhesion between the MBS particles is also weak so that the particles are easily dispersed evenly in the dispersant. Thereby, the product's transparency is increased, while at the same time no separation of the rubber layer and the polyvinyl chloride layer occurs, whereby stress cracking is prevented.

An important point is that the MBS resins obtained by the present invention are evenly dispersible in solvents such as benzene, toluene and tetralin and that the specific viscosity gp/G (4-g/litre, benzene) of the solution lies within the range 0.01 to 0.06. The reduced specific viscosity of an MBS resin according to the invention decreases with increasing degree of crosslinking and increases with decreasing degree of crosslinking.

It has been found that a product with excellent

transparency by mixing and kneading an MBS resin with a ^ gp^ value lower than 0.01 and a polyvinyl chloride. In contrast, the effect on the impact strength is small, and the product does not achieve sufficient toughness without the addition of 20% by weight or more of the MBS resin.

When the /7 gp^ value exceeds 0.06, on the other hand, the impact strength will increase, but as particle dispersion becomes difficult, a sufficiently transparent product cannot be obtained. The product is also highly susceptible to stress cracking.

Many of the MBS or ABS resins (butadiene-styrene-acrylonitrile copolymers) produced by previously known methods are not uniformly dispersible in solvents such as benzene, and those that are uniformly dispersible have a reduced specific viscosity exceeding 0.1. Shaped objects produced from these by mixing with polyvinyl chlorides are also opaque.

During the study of these unfortunate aspects of previously known resins, it has been discovered that for the MBS resin there is a close connection between reduced specific viscosity, transparency and stress cracking, which will be explained in more detail in the

A further feature of the present invention is that the refractive index of MBS resins is simulated using

this, lies within the range 1.528 to 1.54-0. The refractive index for vinyl chloride and copolymers with polyvinyl chloride as the main component is namely 1.530 to 1-538 weighed at 20°C, and it is important that the refractive index of the MBS resin: which is to be mixed with

these, almost completely coincide with these values. If the refractive index lies outside it; above-mentioned area, the resulting shaped objects will become opaque or sometimes give strong purple light scattering.

The refractive index at 20°C, n^,i of polymers of butadiene, methyl methacrylate and styrene are respectively; 1.515, 1.494 and 1.590, and for the polymers according to the invention it thus appears that the addition condition (or the addition rule) due to the weight composition is almost realized.

The accompanying drawing shows a graphic representation in a triangular coordinate system which shows the quantity ratio between three monomer components of MBS resins according to the invention. If the entire resin composition lies within the area delimited by the figure ABCDEP, and the resin at the same time has a gp^ value within the above stated range, mixing with a polyvinyl chloride will lead to transparent objects.

More specifically, it is thus necessary that the composition of the three monomers be made up of 24 to 60$ butadiene, 22 to 43$ styrene and 5 to 46$ methyl methacrylate.

Another important feature of the MBS resins according to the invention is the compositional ratio between the rubber component and the plastic component. If only the impact strength was the problem, naturally the greatest possible rubber content would be desirable. However, if the rubber content is increased to an extreme, agglomeration or lump formation will occur during salting out or drying, or the mixing process with polyvinyl chloride will become difficult, with the result that even dispersion cannot be achieved.

On the other hand, a rubber content of less than 40% by weight will give little impact strength, while it is disadvantageous to add polyvinyl chloride to the impact strength by adding a

large amount of such a weak additive. Other physical properties such as heat and temperature resistance as well as gas permeability will also be unsatisfactory. The weight ratio between

lom the rubber component and the plastic material must therefore preferably lie within the range (40 to 75) : (60 to 25).

A cross-linked butadiene-styrene copolymer is used as the rubber component, whereby the butadiene content should preferably be at least 60% by weight.

By using cross-linked butadiene polymer of butadiene-styrene copolymer, the mixed composition of MBS resin,

which can be produced according to the present invention, and a polyvinyl chloride polymer provide excellent impact strength as well as high transparency compared to the use of non-crosslinked butadiene polymer or butadiene-styrene copolymer.

As a plastic component, a polymer is used which is produced by allowing a monomeric mixture of styrene and methyl methacrylate, which contains a cross-linking agent, to be absorbed and polymerized on the rubber latex particles. It has been shown that the styrene content in the monomer mixture should preferably lie within the range of 40 to 80 percent by weight.

In a few cases, the specific amount of the plastic component can be polymerized on the rubber component in one step. However, it has proven more advantageous to use a two-stage post-polymerization process. This consists of carrying out a first post-polymerisation step, and when this is almost complete, methyl methacrylate or a monomer mixture with styrene with methyl methacrylate as the main component, containing a cross-linking agent, is added, after which a new post-polymerisation step is carried out.

This method further facilitates the mixing of the MBS resin with polyvinyl chloride and increases the rate of dispersion in the vinyl chloride. The amounts of monomer polymerized in the second step should preferably amount to 30% by weight or less of the amounts in the first step. If the plastic component is post-polymerised on the rubber component in two stages, the addition of cross-linking agent in one of the stages can also be omitted.

The cross-linking agents added to the rubber component or the grafting component must be selected from those which readily copolymerize with styrene, butadiene and methyl methacrylate. Examples of such are divinylbenzene and dimethacrylates such as mono-, di-, tri- or tetra-ethylene glycol dimethacrylate and 1,3-butylene glycol dimethacrylate. The cross-linking agents are used in amounts of 0.01 to 5 percent by weight of the total amount of monomer, respectively

tively found in the copolymer.

Suitable polyvinyl chlorides for the present invention are those obtained by known methods such as emulsion polymerization and suspension polymerization. Besides independent polymers, it is also possible to use a copolymer of at least 70% vinyl chloride with other monomers that can be copolymerized with this, for example mono-olefin monomers or mixtures thereof. From 5 to 20 parts by weight of the resin according to the invention is mixed with 95 to 80 percent by weight of a polyvinyl chloride of the above-mentioned type.

The mixing, which can generally be done with powdered materials using equipment such as a roller mill or a Bambury mixer, can also be done by mixing the obtained latex with the polyvinyl chloride latex, after which the resulting mixture is subjected to salting out or spray drying, so that a mixed resin composition is obtained. ;

As mentioned above, MBS resins according to the invention cause the polyvinyl chloride with which these resins are mixed to have high transparency and high impact strength. However, the use of these resins is not limited only to mixing with polyvinyl chloride

in

rides. The MBS resins are therefore suitable for mixing with other resins such as chlorinated; polyvinyl chloride and vinylidene chloride copolymers, which thereby achieve greater impact strength.

The invention shall in it; the following<1> is described in more detail with the help of examples.

Example 1.

In a 10 liter stainless steel autoclave, equipped with a stirring device, a monomer mixture consisting of 1 g of cumene hydroperoxide (CHPi), 800 g of butadiene, 200 g of styrene, 5 g of triethylene glycol dimethacrylate (DMA) and 3000 ml of distilled water containing 10 g Na bisocjtyl sulfosuccinate, 0.05 g EDTA disodium monohydride, 0.5 g rongalite;, 0.03 g iron (II) sulfide °g 0.15 g sodium pyrophosphate. The mix! was brought to reaction at 40°C for approx. 17 hours. After this time, no further pressure drop could be registered.

To the resulting mixture was then added a monomer mixture of 300 g of styrene with a pt content of 0.5 g of CHP and 3 g of DMA, 200 g of methyl methacrylate, 0.3 g of rongalite and 1500 ml of distilled water. The mixture was stirred at high speed for 30 minutes and then heated to 60°C for 15 hours.

The latex thus obtained was cooled to 30°C and 200 g of methyl methacrylate containing 0.2 g of CHP and 1.0 g of DMA, 0.1 g of rongalite and 600 ml of distilled water were added. The mixture was stirred for 130 minutes and then heated to 60°C for 5 hours.

The resulting latex was salted out at 50°C with a 1 percent saline solution and filtered. The filtered off powder particles were washed with water and then dried, whereby an MBS resin with a ^gp^ value of 0.32 was obtained in a yield of 98.5$. 13 parts of this resin were mixed with 87 parts of a polyvinyl chloride having a degree of polymerization of 800, containing 2 parts of dibutyltin dilaurate. The mixture was then kneaded in a rolling mill for 4 minutes at 140°C and then at 180°C pressed out under a pressure of 100 kg/cm into a 33 mm thick plate.

The Charpy impact strength of this plate was determined to

85 kg.cm/cm . The light transmission according to Japan Industrial Standards Designation K 6714 was 81.5$ and the light diffusion (haze value) was 3.5$. Furthermore, practically no buckling was observed when a 1 mm thick plate of the same resin was bent through 180°.

By using a mixture of 0.1 part calcium stearate, 0.36 part zinc stearate and 6 parts of a soybean oil epoxy compound, instead of the above stabilizer, to extrude bottles with a volume of 530 ml and a weight of 25 g, a product with very good transparency was obtained. 50 bottles of this type were cooled to 50°C, filled with water and dropped repeatedly from a height of 1 meter until breakage occurred. The result of this test was an average of 29 falls before breakage. For comparison, the test was carried out with similar bottles of pure polyvinyl chloride. The average result in this case was 2 falls.

Example 2.

The same procedure as in example 1 was followed, except that the degree of cross-linking was changed and that the addition of methyl methacrylate in the second step was carried out in the first step. Representative data for the resulting products are given in Table 1.

Example 3«

The procedure described in example 1 was followed with the exception that divinylbenzene (DVB) was used as crosslinking agent instead of dimethacrylate. <!>

Typical resulting products are shown in table 1.

Claims (3)

1. Process for the production of a copolymer consisting of butadiene-styrene-methyl methacrylate, to be mixed into polyvinyl chloride or polyvinylidene chloride to improve its properties, such as transparency, impact strength, bending properties, etc., characterized in that an elastomer latex is first formed by copolymerizing butadiene and styrene, where butadiene preferably constitutes at least 60$, in the presence of 0.01 - 5% by weight of a copolymerizable crosslinking agent consisting of a dimethyl acrylate or divinylbenzene, and that then 40 - 75 parts by weight of this elastomer are added 25 - 60 parts by weight of a mixture of styrene and methyl methacrylate containing 0.01 - 5 parts by weight of the above crosslinking agent, after which it is stirred and heated to form a graft copolymer, and then cooled, and then, optionally after addition of further methyl methacrylate, reheated to to polymerize further. 2. Method in accordance with claim 1, characterized in that the quantitative ratio between styrene and methyl methacrylate which is subjected to post-polymerization is 40 to ■80 parts by weight to 60 to 20 parts by weight. 3. Method in accordance with claim 1, characterized in that 70 percent by weight or more of the styrene and methyl methacrylate to be post-polymerized in the first step together with the cross-linking agent are brought to polymerization with the elastomeric latex, after which methyl methacrylate and any remaining styrene are brought to polymerization together with the crosslinker after the first post-polymerization step is almost complete.