KR102105471B1 - Acrylic processing aid and vinyl chloride resin composition containing thereof - Google Patents

Abstract

The present invention relates to an acrylic processing aid and a vinyl chloride-based resin composition comprising the same, and more specifically, to process a vinyl chloride-based resin composition using a phosphate-based emulsifier and a pH adjusting agent when preparing an acrylic processing aid having a core-shell structure. When used as a preparation, the present invention relates to an acrylic processing aid and a vinyl chloride-based resin composition comprising the same, which increases compatibility with a vinyl chloride-based resin and melt pressure to improve processability and improves foam formability.

Description

Acrylic processing aid and a vinyl chloride resin composition containing the same {Acrylic processing aid and vinyl chloride resin composition containing thereof}

The present invention relates to an acrylic processing aid for improving foamability and at the same time to increase the processability by improving the compatibility and thermal stability with the vinyl chloride-based resin and a vinyl chloride-based resin composition comprising the same.

The vinyl chloride-based resin is a homopolymer of vinyl chloride or a hybrid polymer containing 50% or more of vinyl chloride. The vinyl chloride-based resins range from electric wires, electrical machinery products, toys, films, sheets, artificial leather, tarpaulins, tapes, food packaging materials, medical supplies by various processing methods such as foam molding, extrusion molding, injection molding, and calendering. It is widely used as a material for various products.

The vinyl chloride resin has excellent hardness and tensile strength, and in addition to various additives, for example, plasticizers, stabilizers, fillers, pigments, and the like, in order to impart various physical properties and functions, its application fields can be further expanded.

In addition to the method of adding the additives, it is possible to expand the application field of the vinyl chloride-based resin through a change in the processing process. For example, when molding a vinyl chloride-based resin through foam molding, weight reduction of a molded article may be achieved, and a process cost may be reduced. However, during foam molding, when foaming is performed with only a vinyl chloride resin, sufficient elongation and melt strength cannot be obtained, resulting in poor appearance of the molded product, and a problem of low foaming magnification due to large and non-uniform foam cells. In order to solve this problem, a method of mixing a processing aid with a blowing agent and adding it to a vinyl chloride-based resin has been widely studied.

As a representative processing aid, a method was developed in which a high molecular weight acrylate-based processing aid containing methyl methacrylate as a main component is mixed with a blowing agent and added to a vinyl chloride resin.

As an example, US Patent Registration No. 6,391,976 discloses a technique of using an acrylate-based monomer as a methyl methacrylate as a comonomer, and US Patent Registration No. 6,221,966 discloses a latex polymerized using alkyl acrylate as the main monomer. Presented is a technique for producing methyl methacrylate by polymerization.

However, these processing aids have a low pH and the stability of the monomer itself is low, even after polymerization with latex, the pH is still 5 to 6, so the stability of the latex, especially the thermal stability is low. This low thermal stability causes a yellowing phenomenon of the final molded product, which causes a problem of deteriorating product quality.

In addition, the higher the compatibility between the processing aid and the vinyl chloride-based resin, the higher the melt pressure in the foam molding process and the processability can be improved, and the foaming specific gravity of the molded product obtained after foaming is low and the size of the foam cell becomes uniform. . Accordingly, in order to increase compatibility, various additives including a compatibilizer are added, but there are problems such as an increase in cost and a decrease in physical properties due to the addition of additives, and it is still insufficient to provide sufficient processability and moldability during foam molding without a compatibilizer.

U.S. Patent Registration No. 6,391,976, "Processing aid for foam molding use and vinyl chloride resin composition containing the same" U.S. Patent Registration No. 6,221,966, "Vinyl chloride resin composition"

Accordingly, the present inventors conducted various studies to solve the above problems, and when using a specific emulsifier in manufacturing a processing aid and adjusting the pH of the final processing aid to a certain level, compatibility with vinyl chloride-based resins and heat thereof It was confirmed that not only the stability was improved, but also the foamability and formability could be improved.

Accordingly, an object of the present invention is to provide an acrylic processing aid capable of improving compatibility with vinyl chloride resin and thermal stability thereof.

In addition, another object of the present invention is to provide a method for manufacturing the acrylic processing aid.

In addition, another object of the present invention is to provide a vinyl chloride-based resin composition containing the acrylic processing aid.

In order to achieve the above object, the present invention includes an acrylic latex having a core-shell structure,

The core and the shell are copolymerized by containing 0.5 to 3.0 parts by weight of a phosphate-based emulsifier represented by the following Chemical Formula 1 with respect to 100 parts by weight of the total of methyl methacrylate and C1 to C18 alkyl acrylate monomers,

To provide an acrylic processing aid having a pH of 8.0 to 9.0 of the acrylic latex:

(In the formula 1, R, m, and n are as described in the specification)

At this time, the acrylic latex is characterized in that the pH of the powder after drying is 7.0 to 8.0.

In addition, the present invention comprises the steps of preparing a core by mixing and polymerizing methyl methacrylate and C1 to C18 alkyl acrylate as a monomer;

Polymerizing methyl methacrylate and C1 to C18 alkyl acrylates with the obtained core and monomer to prepare an acrylic latex having a core-shell structure; And

Including; adding a pH adjusting agent to the obtained acrylic latex;

Provided is a method for preparing an acrylic processing aid, in which the phosphate-based emulsifier of Chemical Formula 1 is added in an amount of 0.5 to 3.0 parts by weight based on 100 parts by weight of the monomers during the core and shell polymerization.

In addition, the present invention provides a vinyl chloride-based resin composition containing the acrylic processing aid.

The acrylic processing aid according to the present invention not only solves the problem of low thermal stability according to the pH characteristics of the conventional acrylic processing aid, but also increases the compatibility with the vinyl chloride resin.

Accordingly, a certain amount is added as a processing aid in the foaming molding process of the vinyl chloride-based resin to increase the melt pressure and improve the processability while improving the foamability, thereby making it possible to manufacture a high-quality vinyl chloride-based resin molded product.

Hereinafter, the present invention will be described in more detail.

Foam molding is performed by adding a vinyl chloride-based resin and an acrylic processing aid into the mold and then using a foaming agent or applying pressure, and a process of applying temperature to melt the resin is performed in parallel. The acrylic processing aid lowers the thermal stability of the vinyl chloride-based resin due to its low pH property, and compatibility is also unsatisfactory, thereby reducing foamability and formability.

Accordingly, in the present invention, the pH of the acrylic processing aid is adjusted to increase the thermal stability of the vinyl chloride-based resin during foam molding, and by using a specific emulsifier to prepare the acrylic processing aid, the compatibility with the vinyl chloride-based resin is increased, and the foamability is improved. And improve moldability.

Acrylic processing aids are usually introduced into dry powder after latex production through emulsion polymerization such as SLS (sodium lauryl sulfate), where the pH is usually low to 5.0 to 6.0 immediately after latex production, and further lowered to 4.0 to 5.0 after drying. . This low pH causes yellowing of the final molded article after foam molding. Accordingly, in the present invention, the pH is adjusted to 8.0 to 9.0 due to the addition of the pH adjusting agent, and when drying, it is in the neutral range as 6.0 to 7.0. Looking at a preferred experimental example of the present invention, when using an acrylic processing aid having a pH of 6.0 or less, it was confirmed that yellowing (i.e., a high yellow index index) occurs in a molded product obtained after foam molding, and cell uniformity is also lowered. In addition, it was found that the same tendency was observed even at a high value of 10 or more by excessively adding a pH adjusting agent, so that the adjustment of the pH of the processing aid directly affected not only the foam molding process but also the quality of the final molded product.

The pH adjusting agent is not particularly limited in the present invention, and any one may be used as long as it is conventionally used in this field. For example, KOH, NaOH Ca (OH) ₂ , Na ₂ CO, and one selected from the group consisting of combinations of these are possible, and preferably KOH is used.

In addition to the pH adjustment, the present invention uses a phosphate-based emulsifier in the production of acrylic latex to increase compatibility with vinyl chloride-based resins.

The phosphate-based emulsifier uses polyoxyethylene alkylether phosphate sodium (PAP) represented by Formula 1 below:

[Formula 1]

(In the formula 1, R is a C12 to C14 alkyl group,

m is an integer of 1 or 2,

n is an integer from 4 to 8)

In Formula 1, when R is not alkyl having 12 to 14 carbons, the chain of the hydrophobic group is insufficient, and thus the emulsification function is weak, or when the number of carbons is high, the viscosity is high, and there are many difficulties in using it, and the number of n is also 4 to 8 If it escapes, the function as an emulsifier is deteriorated. m is an integer of 1,2, and more preferably 1.

More preferably, the phosphate-based emulsifier of Formula 1 is polyoxyethylene-9-lauryl ether, polyoxyethylene-9-stearyl ether, polyoxyethylene-8-stearyl ether, polyoxyethylene-4-lauryl A phosphate-based compound having one group selected from the group consisting of ether, polyoxyethylene-3,5-lauryl ether, polyoxyethylene-2,3-lauryl ether, and combinations thereof can be used.

The phosphate-based emulsifier of Chemical Formula 1 has a high hydrophobicity due to the presence of 12 to 14 alkyl groups having carbon number, and as it has flexibility, compatibility with a vinyl chloride-based resin is superior to an emulsifier such as SLS. . Due to such high compatibility, it is possible to process at a higher melt pressure during foam molding of the vinyl chloride-based resin and lower the specific gravity of foaming, resulting in improvement of processability and foam formability. According to a preferred experimental example of the present invention, despite having the same pH as the case of using the SLS-based emulsifier (Comparative Example 2) compared to the case of using the phosphate-based emulsifier of Formula 1 (Example 1), the melt pressure and the amount of extrusion As the foaming density is low and the specific gravity increases, a problem arises in that the cell non-uniformity increases.

The phosphate-based emulsifier is preferably used in a certain amount in the process of preparing the acrylic latex, and may be used in an amount of 0.5 to 3.0 parts by weight, more preferably 1.0 to 2.0 parts by weight, based on 100 parts by weight of the monomer. If the content of the phosphate-based emulsifier is less than the above range, sufficient emulsification function cannot be performed. On the contrary, when the above-mentioned range is exceeded, the stability of latex decreases (Comparative Example 4), so within the above range Use it properly.

The acrylic latex according to the present invention has a core-shell structure.

At this time, the core polymer and the shell polymer constituting the core and the shell include a material in which methyl methacrylate and an alkyl acrylate of C1 to C18, which are copolymerizable monomers, are copolymerized.

The phosphate-based emulsifier proposed in the present invention is applied to both the polymerization process of the core and the shell, and is used in an amount of 0.5 to 3.0 parts by weight based on 100 parts by weight of the total of methyl methacrylate and C1 to C18 alkyl acrylate monomers.

The alkyl acrylate of C1 to C18 may be one selected from the group consisting of methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, stearyl acrylate, and combinations thereof. Preferably it may be butyl acrylate.

The monomers represented by the alkyl acrylates of C1 to C18 may be used as the same monomer or different monomers when preparing the core and shell. As an example, according to an embodiment of the present invention, methyl methacrylate / butyl acrylate was mixed and introduced into the core and shell, respectively.

The core polymer and the shell polymer according to the present invention are polymerized in a content ratio of 75 to 95% by weight of methyl methacrylate and 5 to 25% by weight of alkyl acrylate of C1 to C18 so that the total content of monomers during polymerization is 100% by weight. .

If, when the content of the methyl methacrylate is out of the above range, the problem that the processability and moldability of the vinyl chloride resin is lowered through a decrease in overall physical properties occurs.

In addition, when the content of the alkyl acrylate of C1 to C18 is less than the above range, it is difficult to expect the effect of shortening the melting time and reducing the amount of generated hydrate through the use of a processing aid, and conversely, when it exceeds the above range, the melting pressure To reduce the processability, increase the specific gravity of the foam and decrease the uniformity of the cell may cause a problem of reducing the foam formability.

In the composition of the acrylic latex of the present invention, the core and the shell preferably have a weight average molecular weight (Mw) of 2 to 5 million g / mol, respectively. If the molecular weight is less than the above range, the specific gravity of foaming may increase and the foam formability may be poor. On the contrary, when the molecular weight exceeds the above range, a problem may arise in which a fine dispersion melt is generated and processability is poor.

In addition, the acrylic latex may have a core: shell weight ratio of 0.3 to 0.7: 0.3 to 0.7, and in one embodiment of the present invention, a weight ratio of 1: 1 was used. When the content ratio is substantially the same for the composition of the core and the shell, there is no large difference in physical properties, and when using different types of monomers, that is, C1 to C18 alkyl acrylates, properties such as compatibility, dispersibility, and processability are considered. It is the range obtained by.

Acrylic latex having a core-shell structure as described above can be prepared through polymerization in two stages.

Specifically, the acrylic processing aid is to prepare a core by mixing and polymerizing methyl methacrylate and C1 to C18 alkyl acrylate as monomers;

Polymerizing methyl methacrylate and C1 to C18 alkyl acrylates with the obtained core and monomer to prepare an acrylic latex having a core-shell structure; And

Adding a pH adjusting agent to the obtained acrylic latex; prepared through

When polymerizing the core and shell, a phosphate-based emulsifier of Chemical Formula 1 is added.

Hereinafter, each step will be described.

First, a mixture of methyl methacrylate and C1 to C18 alkyl acrylate together with a phosphate-based emulsifier of Chemical Formula 1 is prepared and then a core is prepared through emulsion polymerization.

Various compositions and reaction conditions that require an initiator required for emulsion polymerization are not particularly limited in the present invention and follow what is known in the art.

Water-soluble initiators may be used as the initiator, for example, inorganic peroxides such as sodium persulfate, potassium persulfate, ammonium persulfate, potassium perphosphate, and hydrogen peroxide; t-butyl peroxide, cumene hydroperoxide, p-mentane hydroperoxide, di-t-butyl peroxide, t-butylcumyl peroxide, acetyl peroxide, isobutyl peroxide, octanoyl peroxide, dibenzoyl per Organic peroxides such as oxide, 3,5,5-trimethylhexanol peroxide, and t-butyl peroxyisobutyrate; And nitrogen compounds such as azobisisobutyronitrile, azobis-2,4-dimethylvaleronitrile, azobiscyclohexanecarbonitrile, and azobisisobutyric acid (butyl acid) methyl. These initiators are used in an amount of 0.03 to 0.2 parts by weight based on 100 parts by weight of the total monomer.

The polymerization may be performed at 40 to 80 ° C for 2 to 12 hours.

According to one embodiment of the present invention, during the emulsion polymerization, additives such as redox catalysts, polymerization initiators, emulsifiers (or surfactants), molecular weight modifiers, activators, and ionic water, which are commonly known in the art, may be further included.

The molecular weight modifier is not particularly limited, and examples include mercaptans such as a-methylstyrene dimer, t-nodecyl mercaptan, n-dodecylmercaptan, and octyl mercaptan; Halogenated hydrocarbons such as carbon tetrachloride, methylene chloride and methylene bromide; Sulfur-containing compounds, such as tetraethyl diuram disulfide, dipentamethylene diuram disulfide, and diisopropylkisanthogen disulfide, may be used in an amount of 0.1 to 3 parts by weight based on 100 parts by weight of the monomer mixture.

The activator is not limited thereto, but one or more selected from sodium hydrosulfite, sodium formaldehyde sulfoxylate, sodium ethylenediamine tetraacetate, ferrous sulfate, lactose, dextrose, sodium linolenic acid, and sodium sulfate at each step The monomer may be added in a range of 0.01 to 0.15 parts by weight based on 100 parts by weight.

The redox catalyst is not particularly limited, and may be, for example, sodium formaldehyde sulfoxylate, ferrous sulfate, disodium ethylenediaminetetraacetate, cupric sulfate, etc., 0.01 parts by weight to 0.1 parts by weight based on 100 parts by weight of the monomer mixture It can be used in parts by weight.

Next, the core and methyl methacrylate, C1 to C18 alkyl acrylate, and a phosphate-based emulsifier of Formula 1 are added for emulsion production, followed by emulsion polymerization to prepare an acrylic latex having a core-shell structure.

At this time, emulsion polymerization for shell production is performed in the same manner as described above.

Next, an acrylic processing aid is prepared through a step of adding a pH adjusting agent to the acrylic latex.

As already mentioned, the pH adjusting agent may be one selected from the group consisting of KOH, NaOH Ca (OH) ₂ , NaCO and combinations thereof, wherein the content is not particularly limited in the present invention and the pH of the entire latex is 8.0 to To be 9.0, it can be appropriately added by those skilled in the art.

In addition, the acrylic processing aid can be used in foam molding processing of vinyl chloride-based resins by agglomeration using a conventional acid, salt or polymer flocculant, followed by dehydration and drying to obtain a powder. At this time, the acrylic processing aid in the powder state has a neutral range of pH 7.0 to 8.0.

These acrylic processing aids are used as processing aids in foam molding of vinyl chloride-based resins, and improve thermal stability to suppress yellowing of the final molded product and increase friction due to high compatibility with vinyl chloride-based resins. In addition to promoting processing, it is possible to increase the melt pressure of the vinyl chloride-based resin composition to improve processability. In addition, it can serve to lower the specific gravity of foaming and to make the cell size small and uniform.

Specifically, the acrylic processing aid according to the present invention is added to 0.1 to 30 parts by weight based on 100 parts by weight of the vinyl chloride resin to produce various molded products through foam molding.

When the content of the acrylic processing aid is less than the above range, the processability, moldability and thermal stability due to the use of the processing aid are lowered, thereby deteriorating the quality of the molded product, and conversely, when the content exceeds the above range, the processability is lowered and various mechanical And as the chemical properties rather deteriorate, it is appropriately used within the above range.

In this case, if necessary, various additives commonly used in this field may be further included. The additives include heat stabilizers, lubricants, impact modifiers, plasticizers, UV stabilizers, flame retardants, colorants, fillers, flame retardants, antibacterial agents, mold release agents, heat stabilizers, antioxidants, light stabilizers, compatibilizers, dyes, inorganic additives, surfactants, and nucleating agents. , Additives such as coupling agents, fillers, plasticizers, impact modifiers, admixtures, colorants, stabilizers, lubricants, antistatic agents, pigments, flame retardants can be added, and these can be applied alone or in combination of two or more.

Foam molding using a vinyl chloride-based resin composition is not particularly limited in the present invention, and follows a known method.

The molded article through foam molding has improved foaming magnification and stability of the foam cell during foaming, so that a low specific gravity foam of 0.4 to 0.5 g / cm 3 can be obtained and has a uniform foam cell.

Hereinafter, a preferred embodiment is provided to help the understanding of the present invention, but the following examples are merely illustrative of the present invention, and it is apparent to those skilled in the art that various changes and modifications are possible within the scope and technical scope of the present invention. It is no wonder that such variations and modifications fall within the scope of the appended claims.

Example 1: Preparation of acrylic processing aid

Prepare a 4-neck flask reactor equipped with a stirrer, thermometer, nitrogen inlet, and circulation condenser, 70 parts by weight of deionized water, 0.002 parts by weight of ferrous sulfate, disodium ethylenediamine tetraacetate 0.04 parts by weight was added and the internal temperature of the reactor was maintained at 40 ° C. under a nitrogen atmosphere.

Separated from the reactor, 60 parts by weight of ionic water, 1.0 parts by weight of PAP (sodium salt of polyoxyethylene alkyl ether phosphate), methyl methacrylate, and butyl acrylate were added to prepare a monomer pre-emulsion. At this time, the methyl methacrylate and butyl acrylate were used in an 85:15 weight ratio.

When the internal temperature of the reactor reaches 40 ° C, 50 parts by weight of the monomer pre-emulsion, 0.002 parts by weight of t-butyl hydroperoxide (TBHP) and 0.03 parts by weight of sodium formaldehyde sulfoxylate (SFS) are simultaneously added for primary polymerization for 3 hours. Proceed to prepare a core.

Methyl methacrylate and butyl acrylate were added to 50 parts by weight of the obtained core, and 0.001 parts by weight of t-butyl hydroperoxide and 0.02 parts by weight of sodium formaldehyde sulfoxylate were simultaneously added thereto to perform secondary polymerization. At this time, the methyl methacrylate and butyl acrylate were used in an 85:15 weight ratio.

After 120 minutes of completion of the core addition, 0.002 parts by weight of t-butyl hydroperoxide and 0.004 parts by weight of sodium formaldehyde sulfoxylate were further added and aged for 1 hour to prepare an acrylic latex.

KOH was added to the obtained acrylic latex to adjust the pH of the latex to 8.0.

Example 2

After KOH was added, an acrylic processing aid was prepared in the same manner as in Example 1, except that the pH of the acrylic latex was adjusted to 9.0.

Example 3

When preparing the core and the shell, PAP was added in 2.0 parts by weight, respectively, and after adding KOH, the pH of the acrylic latex was adjusted to 8.5, and the same procedure as in Example 1 was performed to prepare an acrylic processing aid.

Example 4

When preparing the core and the shell, PAP was added in 1.5 parts by weight, and after adding KOH, the pH of the acrylic latex was adjusted to 8.0, and the same procedure as in Example 1 was performed to prepare an acrylic processing aid.

Comparative Example 1

SLS was used instead of PAP, and KOH was not added, and the same procedure as in Example 1 was performed to prepare an acrylic processing aid.

Comparative Example 2

SLS was used instead of PAP, and after the addition of KOH, the pH was adjusted to 8.0, and the same procedure as in Example 1 was performed to prepare an acrylic processing aid.

Comparative Example 3

When preparing the core, 1.0 parts by weight of SLS was used as an emulsifier, and 1.0 parts by weight of PAP was used when producing a shell, and an acrylic processing aid was prepared in the same manner as in Example 1, except that KOH was not added.

Comparative Example 4

When preparing the core and shell, 4.0 parts by weight of PAP was used as an emulsifier, and the pH was adjusted to 8.0 by adding KOH to prepare an acrylic processing aid.

Comparative Example 5

When preparing the core and shell, an acrylic processing aid was prepared in the same manner as in Example 1, except that 1.0 weight part of PAP was used as an emulsifier, and pH was adjusted to 10.0 by adding KOH.

Experimental example

(1) Vinyl chloride resin production

After mixing the acrylic processing aid and the vinyl chloride-based resin prepared in Examples and Comparative Examples, specimens were prepared through foaming.

4 parts by weight of the calcium chloride solution was added to 100 parts by weight of each acrylic latex prepared in Examples and Comparative Examples to obtain a slurry, and the slurry was washed three times with ionic water to remove by-products. Thereafter, the ionic water was removed by filtration and dried at 80 ° C. for 3 hours using a small fluidized bed dryer to obtain an acrylic processing aid powder. At this time, the pH of the obtained acrylic processing aid powder was measured by a pH meter and is shown in Table 1 below.

100 parts by weight of vinyl chloride-based resin (LS 080, manufactured by LG Chemical) 1.5 parts by weight of heat stabilizer OT-700R (Songwon Industry, tin-based heat stabilizer), 0.8 parts by weight of lubricant G-16 (Loxiol), G-70S (Loxiol ) Add 0.5 parts by weight, add 5 parts by weight of the acrylic processing aid (powder) of the examples or comparative examples, and 0.8 parts by weight of the blowing agent azodicarbonamide and mix it while heating to 115 ° C using a Henschel mixer. ) To prepare a vinyl chloride-based resin composition.

(2) Measurement of physical properties

(2-1) Thermal stability (Yellow Index)

The vinyl chloride-based resin composition prepared in (1) was rolled (20 rpm / friction -15%) for 4 minutes at 195 ° C., and a sheet having a thickness of 0.5 mm for measuring thermal stability (yellowness) was prepared. The processed specimen was measured using a color computer (SUGA Color Computer), and the lower the value, the better the thermal stability.

(2-2) Foaming property analysis

The slit die size 2 mm (thickness) x 30 mm (at a cylinder temperature of 180 ° C. and a screw speed of 30 rpm) using the vinyl chloride-based resin composition prepared in Experimental Example (1) using a Haake twin extruder. Area), and then the extrusion amount was measured and the melt pressure value was also measured.

It was cut into lengths of 30 mm and the foam density was measured using a plastic specific gravity meter. At this time, the higher the foaming density, the lower the foaming magnification, indicating that the foaming properties were insufficient. In addition, by observing the cross section of the foamed molded body obtained above with an optical microscope, 5 points when the foamed cells are uniform, 3 points when the foamed cells are slightly uneven, and 1 point when most foamed cells are not uniformed Sex was evaluated. The results obtained at this time are shown in Table 1 below.

Acrylic processing aid pH Yellow Index Foam processing properties Latex powder Melt pressure
(bar) Extrusion amount
(g / min) Specific gravity
(g / cm3) Cell uniformity
(5pt) Example 1 8.0 7.0 9.5 142 196 0.43 4.5 Example 2 9.0 8.0 9.3 145 195 0.42 4.5 Example 3 8.5 7.5 9.7 141 194 0.44 4.5 Example 4 8.0 7.0 9.4 138 190 0.45 4.5 Comparative Example 1 6.0 5.0 21.7 125 175 0.58 2.5 Comparative Example 2 8.0 7.0 15.2 127 178 0.59 2.5 Comparative Example 3 6.0 5.0 17.4 135 184 0.52 3.0 Comparative Example 4 8.0 7.0 - - - - - Comparative Example 5 10.0 9.0 10.2 124 174 0.59 3.0 <Appropriate range of foam processing properties>
Melting pressure: 130 ~ 150 bar
Extrusion amount: 180 ~ 200 g / min
Foam specific gravity: 0.40 to 0.50 g / cm 3

Referring to Table 1, in the case of the vinyl chloride-based resin composition using an acrylic processing aid having a pH adjusted in the present invention, the yellow value of YI was less than 10, indicating that the thermal stability was excellent. have.

In comparison, when the processing aids of Comparative Examples 1, 3 (pH was 6.0) and 5 (pH was 10.0) were used, it was confirmed that a serious yellowing phenomenon occurred as the value of YI was up to 21.7.

In addition, when the foam molding properties are used, when the processing aids of Examples 1 to 4 according to the present invention are used, the melt pressure increases, the specific gravity of the foam decreases, and the cell uniformity improves to have excellent foamability and formability. Was confirmed.

In comparison, it was confirmed that in Comparative Examples 1 and 2 using SLS as the emulsifier, the melt pressure was lowered and the extrusion amount was lowered, as well as the foaming specific gravity increased and the cell uniformity was very low. This tendency was the same in the case of using the processing aid of Comparative Example 3 using a mixture of SLS and PAP.

In addition, in the case of Comparative Example 4 in which PAP was used in excess, it was impossible to obtain a dry sample by agglomeration in the latex state, which means that the stability of the latex was broken by the use of excess PAP.

In Comparative Example 5, even if PAP was used, it was confirmed that the overall foaming properties such as melt pressure, extrusion amount, specific gravity of foam, and cell uniformity were lowered even if the pH of the processing aid was adjusted to 9.0 (powder).

As shown in the results of the above experimental examples, the acrylic processing aid according to the present invention uses PAP as an emulsifier, and by adjusting the pH of the processing aid, ensures high thermal stability during foaming molding of the vinyl chloride-based resin and melt pressure. In addition to improving the foam processability by increasing to an appropriate range, it is possible to increase the foam formability by reducing the specific gravity of the foam and increasing the cell uniformity.

The acrylic processing aid of the present invention is used as a processing aid when manufacturing various molded articles using a vinyl chloride-based resin to enable the production of molded articles having excellent physical properties.

Claims (9)

Core-shell structured acrylic latex,
The core and the shell are copolymerized by containing 0.5 to 3.0 parts by weight of a phosphate-based emulsifier represented by the following Chemical Formula 1 with respect to 100 parts by weight of the total of methyl methacrylate and C1 to C18 alkyl acrylate monomers,
Acrylic processing aid for vinyl chloride resin having a pH of 8.0 to 9.0 of the acrylic latex:
[Formula 1]

(In the formula 1,
R is a C12 to C14 alkyl group,
m is an integer of 1 or 2,
n is an integer from 4 to 8) According to claim 1,
The acrylic latex is an acrylic processing aid for vinyl chloride resin, characterized in that the pH of the powder after drying is 7.0 to 8.0. According to claim 1,
The alkyl acrylates of C1 to C18 are methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, stearyl acrylate, and combinations thereof. Acrylic processing aid for vinyl chloride resin. According to claim 1,
The core and the shell is vinyl chloride, characterized in that the total content of each monomer is polymerized at a content ratio of 75 to 95% by weight of methyl methacrylate, and 5 to 25% by weight of alkyl acrylate of C1 to C18. Acrylic processing aid for resins. Preparing a core by mixing and polymerizing methyl methacrylate and C1 to C18 alkyl acrylate as a monomer;
Polymerizing methyl methacrylate and C1 to C18 alkyl acrylate with the obtained core and monomer to prepare an acrylic latex having a core-shell structure; And
Including; adding a pH adjusting agent to the obtained acrylic latex;
A method for preparing an acrylic processing aid for vinyl chloride-based resin, in which the phosphate-based emulsifier of Chemical Formula 1 is added in an amount of 0.5 to 3.0 parts by weight based on 100 parts by weight of the monomers when polymerizing the core and shell:
[Formula 1]

(In the formula 1,
R is a C12 to C14 alkyl group,
m is an integer of 1 or 2,
n is an integer from 4 to 8) The method of claim 5,
The alkyl acrylates of C1 to C18 are methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, stearyl acrylate, and combinations thereof. Manufacturing method of acrylic processing aid for vinyl chloride resin. The method of claim 5,
The core and shell are vinyl chloride characterized in that the total content of each monomer is used in the range of 75 to 95% by weight of methyl methacrylate, and 5 to 25% by weight of alkyl acrylate of C1 to C18. Method for manufacturing acrylic resin processing aids. The method of claim 5,
The pH adjusting agent is KOH, NaOH Ca (OH) ₂ , Na ₂ CO and a method for producing an acrylic processing aid for a vinyl chloride-based resin, characterized in that it comprises one selected from the group consisting of a combination thereof. With respect to 100 parts by weight of the vinyl chloride resin,
A vinyl chloride-based resin composition comprising 0.1 to 30 parts by weight of the acrylic processing aid of any one of claims 1 to 4.