JPS60215041A - Vinyl chloride resin composition excellent in weather resistance and processability - Google Patents

Abstract

PURPOSE:A vinyl chloride resin composition excellent in weather resistance, processability, and tensile strength, containing a specified copolymer prepared by copolymerizing an acrylic monomer with a rubber-like polymer by two-step graft copolymerization. CONSTITUTION:A graft copolymer is obtained by successively graft-polymerizing 30-10pts.wt. first monomer mixture (consisting of 60-90wt% aromatic vinyl compound, 40-10wt% unsaturated nitrile and 0-20wt% alkyl acrylate wherein the alkyl has 2-8 carbon atoms) and 5-30wt% second monomer mixture (consisting of 50-95wt% methyl methacrylate and 50-5wt% alkyl acrylate wherein the alkyl has 2-8 carbon atoms) with 50-80pts.wt. rubber-like polymer (consisting of 99.5-95wt% alkyl acrylate units wherein the alkyl has 2-8 carbon atoms and 0.5-5wt% polyfunctional crosslinking monomer). 5-50pts.wt. above graft copolymer is mixed with 95-50pts.wt. vinyl chloride resin.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a vinyl chloride resin composition which is highly weather resistant and which simultaneously satisfies impact resistance and tensile strength even when molded under low kneading conditions.

(Prior Art) As is generally known, vinyl chloride resin has poor impact resistance. Many methods have been proposed to improve this impact resistance.

Among these, MBSaW, which is a butadiene-based rubbery polymer graft-polymerized with methacrylic acid methyl ester, styrene, or acrylonitrile, is currently widely used. However, when MBS resin is mixed with vinyl chloride resin, the impact resistance is improved, but the weather resistance is poor, and when the molded product is used outdoors, the impact strength is significantly reduced. Therefore, the use of MBS resin is currently limited.

The main cause of this decrease in weather resistance (hereinafter referred to as weather resistance deterioration) is thought to be based on ultraviolet deterioration of the butadiene unit contained in the MBS resin. A number of methods have been disclosed for improving the weather resistance and imparting impact-strengthening capabilities to MBS resins, such as those described below.

For example, one method that utilizes the grafting active sites of butadiene is to copolymerize an acrylic acid alkyl ester that does not have double viscosity with a small amount of butadiene and a crosslinking agent, and use this as a rubbery polymer.

Using a rubbery polymer produced by this method has improved weather resistance compared to M88 resin, making it possible to use it in fields where it will not be used outdoors for a long time, but the main cause of weather resistance deterioration is the butadiene unit. Because of this, the weather resistance is not sufficiently improved and its uses are substantially limited. In order to obtain a graft copolymer with excellent weather resistance and no double viscosity, a crosslinked acrylic ester rubbery polymer consisting of an acrylic alkyl ester and a crosslinking agent is combined with a methacrylic acid alkyl ester and an aromatic vinyl compound. , a method of grafting an unsaturated nitrile has been proposed (Japanese Patent Publication No. 51-28117).

When a graft copolymer produced by this method is used, the weather resistance of the molded product produced is excellent, and in recent years it has been used in earnest in fields that require long-term weather resistance, such as window frames. However, although the use of graft copolymers produced by this method is satisfactory in terms of weather resistance of the molded products produced, in general, it is difficult to develop strength unless sufficiently kneaded with vinyl chloride resin, so-called The disadvantage is that the area during processing is narrow.

[Structure of the invention]

In view of the above-mentioned circumstances, the present inventors have discovered that during processing there is a wide range of
In other words, sufficient toughness is developed even under low kneading conditions (hereinafter referred to as
As a result of intensive research to obtain a graft copolymer with excellent processability and weather resistance, the present invention was achieved.

That is, the present invention uses acrylic acid alkyl esters having an alkyl group of 2 to 8 carbon atoms in an amount of 99.5 to 95% (wt%).
, hereinafter the same), preferably 99 to 96%, and a polyfunctional crosslinking agent, preferably 0.5 to 5%, preferably a polyfunctional crosslinking agent in which at least one functional group has a different reactivity from other functional groups. First, 50 to 80 parts (by weight, the same shall apply hereinafter), preferably 60 to 75 parts, of a rubbery polymer consisting of 1 to 4%,
As a stage, 60 to 90%, preferably 60 to 80%, of an aromatic vinyl compound, 40 to 10%, preferably 40 to 20%, of an unsaturated nitrile, and an acrylic acid alkyl ester whose alkyl group has 2 to 8 carbon atoms. 30 to 10 parts, preferably 25 to 15 parts of a monomer mixture comprising ~20%, preferably 0 to 10%, are graft-polymerized, followed by a second stage of graft polymerization of 50 to 95 parts of methyl methacrylate.
%, preferably 80-9596 and the number of carbon atoms in the alkyl group is 2
5 to 30 parts of a monomer mixture consisting of 50 to 5%, preferably 20 to 5%, of an acrylic acid alkyl ester of
Preferably 5 to 20 parts are graft-polymerized, and the total! 10
5 to 50 parts of a graft copolymer made into 0 parts and vinyl chloride l1i11i95 to 5 containing 70% or more of vinyl chloride
It relates to a vinyl chloride resin composition having excellent weather resistance, processability, and tensile strength, characterized in that it contains 0 parts and 100 parts.

In graft polymerizing the crosslinked acrylic acid alkyl ester, the graft polymerization is carried out in two stages, and the graft component in the first stage is composed of an aromatic vinyl compound, an unsaturated nitrile, and an acrylic acid alkyl ester used as desired. We have also found that by constructing the second-stage graft component with methyl methacrylate and acrylic ester, the processability of a vinyl chloride resin composition using the obtained graft copolymer can be greatly improved. It was. In other words, it is essential that the first-stage graft component contains an aromatic vinyl compound and an unsaturated nitrile, and only when these monomer components are used in the first stage, processability and impact resistance can be improved. is greatly improved. When these monomer components are graft-polymerized in the second stage, or when all monolayer components are mixed and graft-polymerized without dividing into two stages, vinyl chloride resin using the resulting graft copolymer can be obtained. The processability and impact resistance of the composition are poor. In addition, as the second stage graft component, it has good compatibility with vinyl chloride resin,
It is essential to use methacrylic acid methyl ester which has excellent weather resistance. However, it was found that graft polymerization of methacrylic acid methyl ester alone resulted in poor processability and impact resistance, and copolymerization of methacrylic acid methyl ester and acrylic acid alkyl ester was essential for improving processability and impact resistance. It turned out to be.

Based on the above-mentioned findings, we have now developed a copolymer that has excellent weather resistance and processability, that is, the ability to develop strength even under low kneading conditions.

[Embodiments of the invention]

The rubbery polymer used in the present invention is produced from an acrylic acid alkyl ester and a polyfunctional crosslinking agent.

The acrylic acid alkyl ester which is the main component of the rubbery polymer is an acrylic acid alkyl ester in which the alkyl group has 2 to 8 carbon atoms, such as ethyl acrylate,
Representative examples include propyl acrylate, isobutyl acrylate, isobutyl acrylate, and 2-ethylhexyl acrylate. These may be used alone or in combination.

The polyfunctional crosslinking agent copolymerized with these acrylic acid alkyl esters is important because it functions to make the acrylic acid alkyl ester polymer into crosslinked particles. Examples of such polyfunctional crosslinking agents include those with the same reactivity as functional groups, such as divinylbenzene and polyethylene glycol dimethacrylate, as well as allyl methacrylate,
Examples include those in which the reactivity of the functional group differs by at least 1 m from other functional groups, as exemplified by acrylic acid allyl ester. Among these multifunctional crosslinking agents, those in which the reactivity of at least one of the functional groups is different from the reactivity of the other functional groups can crosslink the acrylic acid alkyl ester polymer with a small amount of the multifunctional crosslinking agent. Therefore, it is preferable.

100 parts of the rubbery polymer used in the present invention contains 99.5 to 95 parts, preferably 99.5 to 95 parts, of the alkyl acrylate ester.
~96 parts and 0.5 to 5 parts, preferably 1 to 4 parts, of the polyfunctional crosslinking agent, and is usually produced by emulsion polymerization. If the amount of the polyfunctional crosslinking agent is less than 0.5 parts, it becomes difficult to form crosslinked particles and the effect of imparting impact resistance is low, which is undesirable. On the other hand, if the amount exceeds 5 parts, the When a vinyl chloride resin composition blended with a graft copolymer produced from a rubbery polymer is molded, the impact resistance decreases, which is undesirable.

The average particle diameter of the rubbery polymer produced in this way is preferably larger from the viewpoint of improving impact resistance, and is practically 1,500 Å or more, preferably 1,500 Å or more.
The thickness is preferably 700 Å or more. There are various methods to obtain the average particle size of such rubbery polymers.
Although there is no particular limitation, particles having an average particle size of about 1,000 particles, which are usually easily produced, may be concentrated and enlarged by a conventional method before graft polymerization. However, it is more preferable to obtain a rubber-like polymer having an average particle diameter of 1500 Å or more by a conventional seed polymerization method, since this reduces the proportion of small particles that contribute little to impact resistance.

In the present invention, a monomer mixture is graft-polymerized to the rubbery polymer thus obtained in a two-stage reaction to obtain a graft copolymer used in the present invention.

The components grafted onto the rubbery polymer in the first stage are:
An aromatic vinyl compound and an unsaturated nitrile are essential, and if desired, an acrylic or acid alkyl ester having an alkyl group of 2 to 8 carbon atoms may be added. Only when the above-mentioned components are graft-polymerized in the first stage, the processability is specifically improved to a large extent for unknown reasons. Processability is not improved even if the components of the first stage are polymerized in the second stage or graft polymerization is performed without dividing into two stages.

It is preferable to configure the first-stage graft component to be a component that is compatible with the vinyl chloride resin because it improves processability and does not cause a decrease in tensile strength, which is a practically important property. From this point of view, the first stage graft component contains 60 to 90% aromatic vinyl compound, preferably 60 to 80%,
Unsaturated nitrile 40-10%, preferably 40-20%
, a component consisting of O to 20%, preferably 0 to 10%, more preferably 0 to 5%, of an acrylic acid alkyl ester having an alkyl group having 2 to 8 carbon atoms.

Examples of the unsaturated nitrile used in the first-stage grafting component include Ac9Q nitrile and methacrylonitrile, and examples of the aromatic vinyl compound include styrene, and other specific examples include vinyltoluene,
Examples of the acrylic acid alkyl ester having an alkyl group of 2 to 8 carbon atoms, which may be used as desired, include those similar to those used in the production of the rubbery polymer. It can be used without being

After the polymerization of the first-stage graft component is substantially completed, methacrylic acid methyl ester and an alkyl group having 2 carbon atoms are combined.
The second stage graft component consisting of the acrylic acid alkyl ester of 1 to 8 is graft-polymerized to produce the graft copolymer used in the present invention.

In order to improve impact resistance, it is essential that the second-stage graft component be a component in which the vinyl chloride resin and the graft copolymer are compatible. If the compatibility between the vinyl chloride resin and the second-stage graft component is insufficient, the impact resistance will be poor and the tensile strength, which is a practically important property, will be significantly reduced. Methyl methacrylate is optimal for imparting this compatibility; if other methacrylic acid alkyl esters are used, the tensile strength will drop significantly and the performance will be insufficient. However, when methacrylic acid methyl ester alone is graft-polymerized in the second stage, the vinyl chloride resin composition produced using the resulting graft copolymer will not be aromatic even in the first stage under low kneading conditions. Even if a group vinyl compound and an unsaturated nitrile are used for graft polymerization, the effect of imparting processability and impact resistance is reduced, which is not preferable.

Although the above reason is not certain, it is presumed to be as follows. That is, the time to reach the maximum torque of the Brabender Plastograph, which is a vinyl chloride resin composition containing a graft polymer obtained by graft polymerization of methyl methacrylate alone in the second stage, tends to be delayed; Even if the eye component is composed of a copolymer consisting of unsaturated nitrile and aromatic vinyl, it is presumed that it is difficult to develop strength under low kneading conditions. On the other hand, the time to reach the maximum torque tends to become faster when methacrylic acid methyl ester is copolymerized with a small amount of acrylic acid alkyl ester.

However, in order to control the time required to reach the maximum torque while maintaining the excellent compatibility of methacrylic acid methyl ester, it is necessary to carefully examine the amount and type of acrylic acid alkyl ester used.

For this reason, the graft component in the second stage is methacrylic acid methyl ester ζ~95%, preferably 80~95%.
5%, acrylic acid alkyl ester 50-5%, preferably 20-5%.

When the amount of acrylic acid alkyl ester exceeds 50%,
The compatibility of methacrylic acid methyl ester is impaired, resulting in a significant decrease in tensile strength.On the other hand, depending on the type of acrylic acid alkyl ester, the obtained graft copolymer may become lumpy during salting out or acid precipitation. There is also.

On the other hand, if it is less than 5%, the time to reach the maximum torque of the Brabender Plastograph will not be improved and is not practical. In order to efficiently express the effect with a small amount, acrylic ester copolymerized with methyl methacrylate is preferably acrylic ether, n-butyl acrylate, or 2-ethylhexyl acrylate. However, the present invention is not limited to these, and any acrylic acid alkyl ester in which the alkyl group has 2 to 8 carbon atoms may be used.

Next, the usage ratios of the rubbery polymer, the first-stage graft component, and the second-stage graft component will be explained.

In the first stage graft component, 30 to 10 parts, preferably 25 to 15 parts, are graft-polymerized to 50 to 80 parts, preferably 60 to 75 parts, of the rubbery polymer by a conventional method. The amount of rubbery polymer is 50 parts per 100 parts of the graft copolymer after the second stage graft polymerization.
If the amount is less than 1%, the impact resistance of molded products made from vinyl chloride resin compositions produced using the graft copolymer will be poor;
On the other hand, if the amount exceeds 80 parts, the mixture becomes late during salting out or acid precipitation or during drying after the second stage graft polymerization is completed, making it difficult to mix uniformly with the vinyl chloride resin.

In addition, the rubber-like polymer of the first stage graft component is 50 to 80%
If the proportion exceeds 30 parts, this is presumed to be due to an increase in the proportion of the aromatic vinyl compound in the graft copolymer after the second-stage graft polymerization. When molded products made from vinyl chloride resin compositions are left outdoors, they undergo significant discoloration, and in extreme cases, they turn black.

On the other hand, if the amount of the graft component is less than 10 parts, the effect of improving processability in a vinyl chloride resin composition will be reduced.

The graft component in the second stage is a total of 50 to 80 parts of the rubbery polymer graft-polymerized as described above, and the copolymer consisting of 30 to 10 parts of the graph 1 component in the first stage. 5 to 30 parts are grafted so that the amount becomes 100 parts. If the amount of the second-stage dalat component is less than 5 parts or more than 30 parts, the effect of improving processability in a vinyl chloride resin composition will be reduced, which is not preferable.

The graft copolymer latex thus obtained is coagulated by salting out or acid precipitation, filtered and washed, and then dried and recovered. During coagulation, a known anti-aging agent or ultraviolet absorber may be added.

The obtained graft copolymer is mixed with a vinyl chloride resin by a conventional method to produce a vinyl chloride resin composition. The vinyl chloride resin used in the present invention is a concept that includes vinyl chloride homopolymers, copolymers with a vinyl chloride content of 10% or more, and vinyl chloride resin derivatives such as chlorinated polyvinyl chloride.

The amount of graft copolymer mixed with vinyl chloride resin varies depending on the application, but generally vinyl chloride resin 97-5
0 parts and 3 to 50 parts of the graft copolymer are mixed to prepare 100 parts of a vinyl chloride resin composition.

Next, the composition of the present invention will be explained in more detail based on Examples.

Example 1 (A) Production of seeds used in the production of rubbery polymers A glass reactor equipped with a thermometer, a stirrer, a reflux condenser, a nitrogen inlet device, and a monomer addition device was as follows. I prepared Chino.

Distilled water 250 parts Rosin acid potassium 0.5 Sodium oleate 0.5! .

Demol N O12.

formaldehyde sulfoxy Sodium fluoride (SFS) 0.2.

Na3PO4・12H200,45nEDTA・2
Na O,008! I Ferrous sulfate heptahydrate 0.002+! Thereafter, it was heated to 40°C while stirring in a nitrogen stream,
100 parts of n-butyl acrylate, 2 parts of allyl methacrylate
．． 5% of a monomer mixed solution containing 0 part of coumaine hydroperoxide and 0.1 part of cumain hydroperoxide was charged. Then, the remaining 95% monomer mixed solution was added dropwise over a period of 4 hours. After addition 1
．． Polymerization was carried out after 5 hours to make the polymerization thick.

The yield of the obtained polymer was 97%, and the average particle diameter of the obtained latex was 900^.

The Demol N is a naphthalene sulfonic acid formalin composite manufactured by Kao Atlas ■.

(B) Production of rubber-like polymer Seed polymerization was carried out using the latex obtained in (A) as a seed.

Rubber latex obtained from 250 parts of distilled water (A) 10 Il (as solid content) SFS O
12.

EDTA-2Na O,008++ Ferrous sulfate heptahydrate 0.002. + A mixture of the above composition was charged into a glass reactor, heated to 40°C, and then a monomer mixture of 90 parts of n-butyl acrylate, 2 parts of allyl methacrylate, and 0.1 part of cumene hydroperoxide was added continuously for 4 hours. added. Simultaneously with the addition of the monomer mixture, 1 part of a 5% aqueous solution of sodium oleate was added continuously over a period of 4 hours. After the addition was completed, polymerization was further carried out for 2 hours to obtain a rubbery polymer latex.

The conversion rate of the monomer mixture was 96%, and the average particle size of the obtained latex was 2,000 particles.

(C) Production of graft polymer: Charge raw materials into a glass reactor to have the following composition.
It was heated at 0°C under a nitrogen stream.

Rubber-like product obtained from (B) Polymer latex 65 parts (as solid content) SFS O, 2, + EDTA-2Na 0.01 # Ferrous sulfate heptahydrate 0.005. + The monomer mixture described below was then added over a period of 2 hours.

Styrene 18 parts Acrylonitrile 6 parts Cumene hydroperoxide 0.2 After completion of addition,
When the reaction was continued for an additional hour, the conversion rate was 96%.

The monomer mixture described below was then added over a period of 1 hour.

Methyl methacrylate 9 parts Butyl acrylate 2 After addition of cumene hydroperoxide 0.1n,
When polymerization was continued for an additional hour, the conversion rate was 98%.

The obtained graft copolymer latex was salted out and dehydrated and dried to obtain the desired graft copolymer.

The obtained graft copolymer was blended according to the following formulation, and a 1-inch diameter vinyl chloride pipe was molded using an 80 mm diameter twin-screw extruder in different directions, and the falling weight impact strength and tensile strength were measured by the following method.

Compounding and disposal vinyl chloride resin < p -1ooo) 10 parts Graft copolymer 7 n Lead-based stabilizer 2 n Calcium stearate I n Wax-based lubricant 0.5 n In addition, using the above-mentioned formulation, the gelling properties of Brabender Plastograph was measured by the method below. The results obtained are shown in Table 1.

(Falling weight impact strength) Measurement was performed at 0° C. using 40 samples using a 20 kg flat bottom weight, and the half height of failure was determined by the Dixon mode method.

(Tensile strength) After measuring at 23℃, 20℃ according to JISK 6741
Convert to.

(Time to reach maximum torque of Brabender Plastograph) Using a composition with a predetermined composition, the chamber temperature was 190°C in Brabender Plastograph manufactured by Brabender.
, measured under the condition of 30 rotations.

Examples 2 to 4 and Comparative Examples 1 to 3 Graft copolymers were produced in the same manner as in Example 1, except that the graft monomer composition was changed as shown in Table 1, and a vinyl chloride resin composition was prepared. The physical properties of the molded article and the properties of the composition were measured.

The results are shown in Table 1.

Comparative Examples 4-5 Graft copolymers were produced in the same manner as Examples 1-2, except that the order of addition of the first-stage and second-stage graft monomers in Examples 1-2 was reversed. A vinyl chloride resin composition was prepared, and the physical properties of the molded article and the properties of the composition were measured.

The results are shown in Table 1.

Comparative Example 6 A graft copolymer was produced in the same manner as in Example 1, except that the graft monomer components were mixed without dividing into two stages, and were added in one stage for 3 hours, and a vinyl chloride resin composition was prepared. The molded product physical properties and composition characteristics were measured. The results are shown in Table 1.

As shown in Table 1, vinyl chloride resin compositions with excellent impact resistance, processability, and tensile strength are prepared by dividing the rubber-like polymer from graph 1 to monomer into two stages. A graft obtained by graft copolymerization of a component mainly consisting of an aromatic vinyl compound and an unsaturated nitrile as a body component, and a component consisting of a methyl methacrylate ester and an alkyl acrylate ester as a second monomer component. It can be obtained by using a copolymer.

Claims (1)

[Scope of Claims] 1 99.5 to 95% by weight of an acrylic acid alkyl ester whose alkyl group has 2 to 8 carbon atoms and 0 polyfunctional crosslinking agent
．． First, as a first stage, 60 to 80 parts by weight of a rubbery polymer consisting of 5 to 5% by weight of an aromatic vinyl compound is added.
Graft-polymerize 30 to 10 parts by weight of a monomer mixture consisting of 90% by weight, 40 to 10% by weight of unsaturated nitrile, and 0 to 20% by weight of an acrylic acid alkyl ester whose alkyl group has 2 to 8 carbon atoms, and then As the second step,
5 to 30 parts by weight of a monomer mixture consisting of 50 to 95% by weight of methyl methacrylate and 50 to 5% by weight of alkyl acrylate whose alkyl group has 2 to 8 carbon atoms is graft-polymerized to give a total of 100 parts by weight. 5 to 50!1 parts of a graft copolymer, and a vinyl chloride resin 9 containing 70% by weight or more of vinyl chloride.
A vinyl chloride resin composition having excellent weather resistance, processability, and tensile strength, characterized by blending 5 to 50 parts by weight to 100 parts by weight.