JP2021066878A - Processing aid and resin composition - Google Patents

Abstract

To provide a processing aid that improves homogeneously the molten tension of a resin composition, to improve the moldability or improve the powder flowability of the processing aid, thereby achieving excellent blocking resistance.SOLUTION: A processing aid has a polymer A with a weight average molecular weight of 2000,000 or more and with a glass transition temperature of 50°C or lower and a polymer B with a weight average molecular weight of 1500,000 or less and with a glass transition temperature of 70°C or higher. The content of the polymer A is higher than the content of the polymer B.SELECTED DRAWING: None

Description

The present invention relates to a processing aid that improves processability during resin molding, and a resin composition containing the same.

The melt tension during the molding process of the resin is a key factor for the success of the molding process operation. For example, when the melt tension is high, in foam molding, the structure of the foam cell is fixed, and a homogeneous molded product having a high foaming ratio can be obtained. In deformed extrusion, it becomes easy to take out the molten resin through a die or sizing, which leads to an improvement in productivity. By increasing the melt tension of the resin in this way, many advantages can be obtained in the molding process.

As a method of increasing the melt tension of the resin composition, a method of using a matrix resin having a high molecular weight is known. However, when the molecular weight of the matrix resin is increased, the melt viscosity also increases with the melt tension, which may make processing difficult with a general molding apparatus. In addition, when the molecular weight of a resin such as a vinyl chloride resin that takes a long time to melt is increased, the melting becomes slower and the processability is significantly impaired.

In order to solve the above-mentioned problems, a method of adding a high molecular weight processing aid to a resin composition is widely known (Patent Documents 1 and 2).

Japanese Patent Application Laid-Open No. 2019-502804 U.S. Pat. No. 3,833,686

Patent Document 1 discloses a method of improving the dispersibility in a resin and improving the melt tension during processing by lowering the glass transition temperature of the processing aid. However, since the powder particles of the processing aid having a low glass transition temperature are easily fused, the powder fluidity of the processing aid is low, and the processing aid stays or blocks in the resin molding process. However, it becomes a factor that lowers the productivity of the resin molded product.

Patent Document 2 discloses that by covering a polymer having a low glass transition temperature with a polymer having a high glass transition temperature, it is possible to prevent powder fusion and improve the powder fluidity of the processing aid. There is. However, since a polymer having a high glass transition temperature has a low dispersibility in a resin, the tension of the molten resin is biased, which adversely affects homogeneous processing and does not provide sufficient performance as a processing aid. ..

The present invention solves the above problems, and uniformly improves the melt tension of the resin composition to improve the molding processability and the powder fluidity of the processing aid to improve the excellent blocking resistance. It is an object of the present invention to provide a processing aid capable of realizing the properties.

The present invention has the following aspects.
[1] Polymer A having a weight average molecular weight of 2 million or more and a glass transition temperature of 50 ° C. or less, and polymer B having a weight average molecular weight of 1.5 million or less and a glass transition temperature of 70 ° C. or more. A processing aid containing more of the polymer A than the polymer B.
[2] The processing aid according to [1], which contains at least one unit of an alkyl (meth) acrylate having an alkyl group having 2 or more carbon atoms as a constituent unit of the polymer A.
[3] As a constituent unit of the polymer B, one or more units selected from the group consisting of methyl (meth) acrylate, a copolymer of aromatic vinyl and vinyl nitrile, and a vinyl halide are included [1]. ] Or the processing aid according to [2].
[4] The ratio of the polymer A to 100% by mass of the total mass of the polymer A and the polymer B is 55% by mass or more and 99% by mass or less, and the ratio of the polymer B is 1% by mass or more and 45% by mass. The processing aid according to any one of [1] to [3], which is less than or equal to%.
[5] The ratio of one or more alkyl (meth) acrylate units having an alkyl group having two or more carbon atoms to all the structural units constituting the polymer A is 20% by mass or more and 100% by mass or less, and methyl. The method according to any one of [1] to [4], wherein the total ratio of the units of the (meth) acrylate, the copolymer of aromatic vinyl and vinyl nitrile, and the vinyl halide is 0% by mass or more and 80% by mass or less. Processing aid.
[6] The ratio of one or more alkyl (meth) acrylate units having an alkyl group having two or more carbon atoms to all the structural units constituting the polymer B is 0% by mass or more and 45% by mass or less, and methyl. The method according to any one of [1] to [5], wherein the total ratio of the units of the (meth) acrylate, the copolymer of aromatic vinyl and vinyl nitrile, and the vinyl halide is 55% by mass or more and 100% by mass or less. Processing aid.
[7] The processing aid according to any one of [1] to [6], wherein the ratio of the unit of methyl methacrylate to all the constituent units of the polymer A is 1% by mass or more and 80% by mass or less.
[8] The processing aid according to any one of [1] to [7], wherein the ratio of the unit of methyl methacrylate to all the constituent units of the polymer B is 65% by mass or more and 100% by mass or less.
[9] Polymer A having a weight average molecular weight of 2 million or more and a glass transition temperature of 50 ° C. or less, polymer B having a weight average molecular weight of 1.5 million or less and a glass transition temperature of 70 ° C. or more, and a matrix. A resin composition containing a resin and containing more of the polymer A than the polymer B.
[10] The resin composition according to [9], wherein the total ratio of the polymer A and the polymer B to 100 parts by mass of the matrix resin is 0.1 part by mass or more and 30 parts by mass or less.
[11] The resin composition according to [9] or [10], wherein the matrix resin is a vinyl chloride resin.

According to the present invention, a processing aid capable of uniformly improving the melt tension of the resin composition to improve molding processability, improving the powder fluidity of the processing aid, and achieving excellent blocking resistance. Can be provided.

The definitions of the following terms apply throughout the specification and claims.
"(Meta) acrylate" means "acrylate" or "methacrylate".

Hereinafter, the present invention will be described in detail.
<Processing aid>
The processing aid of the present invention contains polymer A and polymer B, and may contain a third component or the like in addition to these. Specifically, at least, the processing aids are polymer A having a weight average molecular weight of 2 million or more and a glass transition temperature of 50 ° C. or less, and a processing aid having a weight average molecular weight of 1.5 million or less and a glass transition. It contains a polymer B having a temperature of 70 ° C. or higher, and further contains a larger amount of the polymer A than the polymer B. When the resin composition contains the processing aid, the mechanism is not clear, but the melt tension of the resin composition is uniformly improved, and the molding processability and the powder fluidity of the processing aid are improved. Therefore, excellent blocking resistance can be realized.

The ratio of the polymer A to the polymer B contained in the processing aid of the present invention is such that the polymer A is contained in a larger amount than the polymer B as described above, that is, the total mass of the polymer A and the polymer B is 100 mass. If the ratio of the polymer A to% is larger than 50% by mass, there is no particular limitation, but from the viewpoint of obtaining good processability and powder handling, the total mass of the polymer A and the polymer B is 100% by mass. The polymer A is preferably 55% by mass or more and 99% by mass or less, the polymer B is preferably 1% by mass or more and 45% by mass or less, and the polymer A is 70% by mass or more and 99% by mass or less. It is more preferable that the polymer B is 1% by mass or more and 30% by mass or less, the polymer A is 75% by mass or more and 95% by mass or less, and the polymer B is 5% by mass or more and 25% by mass or less. Especially preferable.

The weight average molecular weight of the processing aid of the present invention is preferably 2 million or more, more preferably 3 million or more, and particularly preferably 4 million or more, from the viewpoint of obtaining good processability.

<Polymer A>
The weight average molecular weight of the polymer A of the present invention can be adjusted by changing the radical polymerization initiator, the polymerization temperature, and the polymerization time, and from the viewpoint of obtaining good processability, the lower limit side is preferably 2 million or more, preferably 3 million. The above is more preferable, 4 million or more is particularly preferable, 4.5 million or more is most preferable, while the upper limit side is preferably 10 million or less, more preferably 8 million or less, and particularly preferably 6 million or less. That is, it is preferable to select the upper and lower limits of the weight average molecular weight of the polymer A within the above range, but among them, 4 million or more and 10 million or less is preferable, 4.5 million or more and 10 million or less is particularly preferable, and 4.5 million or more. Most preferably 8 million or less.

The glass transition temperature of the polymer A of the present invention can be adjusted by changing the charge of the monomer, and is preferably 50 ° C. or lower, more preferably 0 ° C. or higher and 45 ° C. or lower, and 15 ° C. or higher from the viewpoint of obtaining good processability. 40 ° C. or lower is particularly preferable.

The structural unit of the polymer A of the present invention preferably contains a unit of an alkyl (meth) acrylate having an alkyl group having 2 or more carbon atoms, and includes a unit of an alkyl acrylate having an alkyl group having 2 or more carbon atoms. Is more preferable.

Examples of the alkyl (meth) acrylate having an alkyl group having 2 or more carbon atoms include ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, pentyl (meth) acrylate, and hexyl (meth) acrylate. Linear alkyl (meth) acrylate; isopropyl (meth) acrylate, isobutyl (meth) acrylate, s-butyl (meth) acrylate, t-butyl (meth) acrylate, isopentyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, Such as branched alkyl (meth) acrylates; cyclic alkyl (meth) acrylates such as cyclopropyl (meth) acrylate, cyclobutyl (meth) acrylate, cyclopentyl (meth) acrylate, cyclohexyl (meth) acrylate, and the like. These may be used alone or in combination of two or more.

Among them, the number of carbon atoms of the alkyl (meth) acrylate having an alkyl group having 2 or more carbon atoms is preferably 2 to 14 carbon atoms of the alkyl group from the viewpoint of obtaining good processability, and 2 to 14 carbon atoms of the alkyl group. 10 is more preferable.

The ratio of the unit of the alkyl (meth) acrylate having an alkyl group having 2 or more carbon atoms to all the structural units constituting the polymer A is not particularly limited, but is 20% by mass from the viewpoint of obtaining good processability. It is preferably 100% by mass or less, more preferably 25% by mass or more and 90% by mass or less, and particularly preferably 30% by mass or more and 80% by mass or less.

The constituent unit of the polymer A of the present invention may further contain one or more units selected from the group consisting of methyl (meth) acrylate, a copolymer of aromatic vinyl and vinylnitrile, and a vinyl halide. .. The ratio of these structural units to all the structural units constituting the polymer A is not particularly limited, but is preferably 0% by mass or more and 80% by mass or less from the viewpoint of obtaining good processability, and is preferably 10% by mass. It is more preferably% or more and 75% by mass or less, and particularly preferably 20% by mass or more and 70% by mass or less.

Examples of aromatic vinyl include styrene and α-methylstyrene, examples of vinylnitrile include acrylonitrile and metaclonitrile, and examples of vinyl halides include vinyl chloride.

When the constituent unit of the polymer A contains a methyl methacrylate unit, the ratio of the methyl methacrylate unit to all the constituent units constituting the polymer A is not particularly limited, but from the viewpoint of obtaining good processability, one mass is obtained. % Or more and 80% by mass or less, more preferably 50% by mass or more and 75% by mass or less, and more preferably 50% by mass or more and 70% by mass or less. In this case, the ratio of the alkyl (meth) acrylate unit having an alkyl group having 2 or more carbon atoms to all the structural units constituting the polymer A is preferably 20% by mass or more and 99% by mass or less, preferably 25% by mass. It is more preferably 50% by mass or less, and further preferably 30% by mass or more and 50% by mass or less.

As the polymer A, one kind of polymer may be used, or two or more kinds of polymers may be used.

<Polymer B>
The mass average molecular weight of the polymer B of the present invention can be adjusted by changing the radical polymerization initiator, the polymerization temperature, and the polymerization time, and is preferably 1.5 million or less, more preferably 1 million or less, from the viewpoint of obtaining good processability. Preferably, 500,000 or less is particularly preferable, while 50,000 or more is preferable, 100,000 or more is further preferable, and 120,000 or more is particularly preferable.

The glass transition temperature of the polymer B can be adjusted by changing the charge of the monomer, and is preferably 70 ° C. or higher, more preferably 80 ° C. or higher, and particularly preferably 90 ° C. or higher.

As a constituent unit of the polymer B, a unit of one or more alkyl (meth) acrylates having an alkyl group having two or more carbon atoms may be contained.

Examples of the alkyl (meth) acrylate having an alkyl group having 2 or more carbon atoms include ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, pentyl (meth) acrylate, and hexyl (meth) acrylate. Linear alkyl (meth) acrylate; isopropyl (meth) acrylate, isobutyl (meth) acrylate, s-butyl (meth) acrylate, t-butyl (meth) acrylate, isopentyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, Such as branched alkyl (meth) acrylates; cyclic alkyl (meth) acrylates such as cyclopropyl (meth) acrylate, cyclobutyl (meth) acrylate, cyclopentyl (meth) acrylate, cyclohexyl (meth) acrylate, and the like. These may be used alone or in combination of two or more.

Among them, the number of carbon atoms of the alkyl (meth) acrylate is preferably 2 to 14 from the viewpoint of obtaining good processability, and more preferably 2 to 10 carbon atoms.

The ratio of the unit of the alkyl (meth) acrylate having an alkyl group having 2 or more carbon atoms to all the structural units constituting the polymer B is not particularly limited, but is 0 from the viewpoint of obtaining good powder handling. It is preferably 0% by mass or more and 45% by mass or less, more preferably 0% by mass or more and 20% by mass or less, and particularly preferably 1% by mass or more and 20% by mass or less.

The constituent unit of the polymer B preferably contains one or more units selected from the group consisting of methyl (meth) acrylate, a copolymer of aromatic vinyl and vinyl nitrile, and a vinyl halide. The ratio of these structural units to all the structural units constituting the polymer B is not particularly limited, but is preferably 55% by mass or more and 100% by mass or less from the viewpoint of obtaining good powder handling. It is more preferably 80% by mass or more and 100% by mass or less, and can be set to 80% by mass or more and 95% by mass or less.

Examples of aromatic vinyl include styrene and α-methylstyrene, examples of vinylnitrile include acrylonitrile and metaclonitrile, and examples of vinyl halides include vinyl chloride. Since the homopolymers of aromatic vinyl and vinyl nitrile are incompatible with vinyl chloride resin and the like, it is necessary to use a copolymer of aromatic vinyl and vinyl nitrile when using it as a constituent component of polymer B. Is.

When the unit of methyl methacrylate is included as the structural unit of the polymer B, the ratio of the unit of methyl methacrylate to all the structural units constituting the polymer B is 65 mass from the viewpoint of obtaining good processability and powder handling. It is preferably% or more and 100% by mass or less, more preferably 80% by mass or more and 100% by mass or less, and can be set to 80% by mass or more and 95% by mass or less. In this case, the ratio of the unit of the alkyl (meth) acrylate having an alkyl group having 2 or more carbon atoms to all the structural units constituting the polymer B can be set in the range of 0% by mass or more and 35% by mass or less.

As the polymer B, one kind of polymer may be used, or two or more kinds of polymers may be used.

As described above, the processing aid may contain a third component. The third component is not particularly limited, and examples thereof include known silica, talc, calcium carbonate, hydrotalcite, and zeolite. The ratio of the third component to the total mass of the processing aid is not particularly limited, but is preferably 0% by mass or more and 3% by mass or less.

<Manufacturing method of processing aid>
The polymerization method for obtaining the processing aid of the present invention is, for example, an emulsion polymerization method, a soap-free polymerization method, a miniemulsion polymerization method, a suspension polymerization method, or the like, and is not particularly limited. A polymerization method and a soap-free polymerization method are preferable.

Examples of the polymerization initiator used in the production of the processing aid include water-soluble, oil-soluble single-based or redox-based polymerization initiators. Specifically, an ordinary inorganic polymerization initiator such as persulfate is used alone, or an inorganic polymerization initiator is combined with sulfite, hydrogen sulfite, thiosulfate, etc. as a redox-based initiator. It can also be used. Further, organic peroxides such as t-butyl hydroperoxide, cumene hydroperoxide, benzoyl peroxide, lauroyl peroxide, azo compounds and the like are used alone, or these are combined with sodium formaldehyde sulfoxylate and the like to redox. Although it can be used as a system initiator, the present invention is not limited to these specific examples.

For example, when a processing aid is produced by an emulsion polymerization method, the emulsifier used in the emulsion polymerization method is an anionic surfactant such as an alkyl sulfonate, an alkyl benzene sulfonate, an alkyl phosphate, or a dialkyl sulfosuccinate; Nonionic surfactants such as polyoxyethylene alkyl ethers, polyoxyethylene fatty acid esters, sorbitanic acid fatty esters, glycerin fatty acid esters, etc .; cationic surfactants such as alkylamine salts, etc., but not particularly limited, but sulfone. Acid-based anionic surfactants are preferred, and alkyldiphenyl ether disulfonates are more preferred. These emulsifiers may be used alone or in combination of two or more.

The method for recovering the processing aid in the form of powder is not particularly limited. For example, when the processing aid is produced by the emulsion polymerization method, the latex of the obtained copolymer is cooled, and then sulfuric acid and hydrochloric acid are used. The copolymer is precipitated by acid coagulation or salting out with an acid such as, or an electrolyte such as a salt of aluminum chloride, calcium chloride, magnesium sulfate, aluminum sulfate, calcium acetate, etc., and then further filtered and washed. It can be dried to obtain a processing aid. In addition, the processing aid can be recovered in powder form by various methods such as spray drying and freeze drying.

The powder of the processing aid may be a powder obtained by pulverizing the latex of the copolymer produced in one pot, or may be pulverized by blending different latex produced separately, or pulverized separately. It may be a blend of different polymers.

The processing aid preferably has appropriate blocking resistance, gelling properties and melt tension. Specifically, in order to uniformly improve the melt tension of the resin composition to improve the molding processability and improve the powder fluidity of the processing aid to realize excellent blocking resistance, which will be described later. It is preferable that the blocking resistance in the evaluation / measurement method in the above embodiment is "○", the gelling property value is 700 sec or less, and the melt tension is 0.22 N or more at the same time. ..

<Resin composition>
The resin composition contains at least a matrix resin and a processing aid. That is, the resin composition contains at least a matrix resin, a polymer A, and a polymer B, and contains more of the polymer A than the polymer B. The matrix resin may be a thermosetting resin or a thermoplastic resin, and is not particularly limited, but is preferably a thermoplastic resin, more preferably a vinyl halide resin, and particularly preferably a vinyl chloride resin.

The vinyl chloride resin is a homopolymer of a vinyl chloride monomer and a copolymer containing a unit of one or more monomers selected from a group of monomers copolymerizable with the vinyl chloride monomer and a unit of a vinyl chloride monomer. The content ratio of the unit of vinyl chloride monomer in the copolymer is preferably 50% by mass or more and 99% by mass or less.

The total ratio of the polymer A and the polymer B to 100 parts by mass of the matrix resin in the resin composition is not particularly limited, but is preferably 0.1 part by mass or more in order to improve the melt tension, and is preferably 0.5. It is more preferably parts by mass or more, particularly preferably 1 part by mass or more, while it is preferably 30 parts by mass or less, more preferably 15 parts by mass or less for improving workability. It is more preferably 10 parts by mass or less, and particularly preferably 8 parts by mass or less.

The resin composition of the present invention may contain other components such as an impact resistance improver, a stabilizer, a lubricant, a plasticizer, a colorant, a filler, a foaming agent, and the like, if necessary.

The ratio of other components to 100 parts by mass of the matrix resin in the resin composition is not particularly limited, but is preferably 0.1% by mass or more, more preferably 1% by mass or more, while the matrix. It is preferably 80% by mass or less, and more preferably 50% by mass or less so as not to impair the properties of the resin.

The resin composition can be kneaded at, for example, 100 ° C. or higher and 250 ° C. or lower by mixing various components and using a kneader such as a Banbury mixer, a kneader, a roll, a ribbon blender, or a Henschel mixer. Further, the kneaded resin composition may be formed into an appropriate shape by extrusion molding, blow molding, injection molding, calender molding, vacuum forming, or the like.

<Glass transition temperature>
"Glass transition temperature" (Tg) refers to the temperature at which the vitreous polymer begins (or stops) the local movement of the polymer chain. The glass transition temperature of the copolymer can be estimated as follows by the Fox formula (Bulletin of the American Physical Society, 1 (3) Page123 (1956)).
1 / Tg = w1 / Tg (1) + w2 / Tg (2)
For copolymers, w1 and w2 refer to the weight fractions of the two comonomeres, and Tg (1) and Tg (2) refer to the glass transition temperatures of the two corresponding homopolymers made from the monomers. For polymers containing 3 or more monomers, an additional term is added (wn / Tg (n)). The glass transition temperature of homopolymers is determined, for example, by "Polymer Handbook," edited by J. et al. Brandrup and E. H. It can be found in Immunology, Interscience Publishing.

<Analysis of processing aids>
The processing aid can be separated by Gradient Polymer Elution Chromatography (GPEC) under the conditions shown below, and the copolymerization composition and weight average molecular weight can be measured.
[GPEC condition]
Equipment: Agilent Technologies Infinity 1260
Detector: Thermo Fisher Scientific Corona VeoRS Column: TSKgel ODS-100V (4.6 x 150 mm, 5 μm)
Column temperature: 40 ° C
Mobile phase: ATN / THF = 100/0 → 0/100 (10 min) → 0/100 (15 min)
Flow rate: 1.0 ml / min
Concentration: 1000 ppm (containing THF BHT)
Injection volume: 1 μl

<Copolymerization composition measurement method>
The copolymer composition of the polymer is identified by Pyrorysis Gas Chromatography-Mass Spectrometry (PY-GC / MS) and Nuclear Magnetic Resonance ( ¹ H-NMR) under the following conditions.
[PY-GC / MS conditions]
Measuring device: GC-7890A, MSD-5975C, EGA / PY-2020D
Measurement conditions: PY / IF 600 ° C / 320 ° C
Column: UA-5 (30 m, 0.25 mm, 0.25 μm)
Carrier gas: helium (1 mL / min)
Detector: MAD (EI)
Oven temperature: 40 ° C (2 min) → temperature rise at 20 ° C / min → 320 ° C (5 min)
Injection port temperature: 320 ° C
Transfer temperature: 320 ° C
Mass spectrum range: 20-1000
Split ratio: 50/1

[ ^{1 1} H-NMR condition]
Equipment: JNM EX-270 manufactured by JEOL Ltd.
Solvent: Deuterated chloroform (7.26 ppm)
Concentration: 20 mg / 65 ml
Temperature: 23 ° C
Accumulation: 64 times

<Method of measuring weight average molecular weight>
The weight average molecular weight of the polymer is identified by Gel Permeation Chromatography (GPC) under the following conditions.
[GPC conditions]
Equipment: Tosoh HLC-8320
Separation column: TSK-guardcolumn HHR (30) (7.5 mmφ × 75 mm) and TSK-GEL GMHHR-H (20) (20 μm, 7.8 mmφ × 300 mm) are connected in series.
Column temperature: 40 ° C
Eluent: Special grade THF (containing stabilizer)
Concentration: 10 mg / 10 ml
Flow velocity: 0.600 ml / min
Injection volume: 10 μl
Detector: RI (Differential Refractometer)
Calibration curve: Monodisperse polystyrene Internal standard: Antage W400

<Evaluation method of blocking resistance of processing aids>
20 g of the processing aid is weighed, placed in a cylindrical mold having a diameter of 65 mm, and further heated at 60 ° C. for 2 hours with a weight of 5 kg placed on the mold as a weight. After heating, take out the test piece of the processing aid that has solidified into a columnar shape, place it on a 12-mesh sieve, and vibrate with the dial 10 of the micro-type electromagnetic vibration sieve (M-2, manufactured by Tsutsui Rikagaku Kikai) for 10 minutes. give away. The mass of the test piece remaining on the sieve after the test is measured, and the rate of decrease in mass with respect to the original test piece is determined. Based on the mass reduction rate of 20%, a sample having a reduction rate of 20% or more is evaluated as “◯” as having good blocking resistance, and a sample having a reduction rate of less than 20% is evaluated as “x” as having poor blocking resistance.

<Evaluation method of gelation characteristics of resin composition>
A plastic coder (manufactured by Brabender) heated to 160 ° C. is filled with 60 g of a vinyl chloride resin composition, held for 3 minutes, and then the gelling characteristics are observed under the conditions of a temperature of 160 ° C. and a rotation speed of 30 rpm. The time required for the torque to exceed 30 Nm after the start of kneading was read as the gelation time. The shorter the gelation time, the more uniformly the processing aid is dispersed and the better the processability. For example, in order to obtain a molded product having a uniform appearance by foam extrusion molding, the gelation time is obtained. Is preferably 700 sec or less, more preferably 680 sec or less, and further preferably gelling time of 675 sec or less.

<Evaluation method of melt tension of resin composition>
A roll sheet is prepared by kneading 250 g of a vinyl chloride resin composition for 3 minutes with a heat roll having a diameter of 8 inches heated to 185 ° C., and the roll sheet is cut into strips (5 mm × 80 mm × 0.5 mmt) for testing. Make a piece. The test piece was put into a twin capillary rheometer (RH-7 manufactured by ROSAND) set at 195 ° C., preheated for 5 minutes, extruded at a piston speed of 8.89 mm / min, and wound with a melt tension of 6 m / min. Was measured. When the melt tension is high, the structure of the foam cell is fixed in the foam molding, and a homogeneous molded product having a high foaming ratio can be obtained. However, in order to obtain a molded product having a good foaming ratio, the melt tension is 0. It is preferably .22N or more, more preferably 0.24N or more, and even more preferably 0.26N or more.

(Manufacturing Example 1)
(Manufacturing of resin composition)
100 parts by mass of vinyl chloride resin (manufactured by Shinetsu Chemical Industry Co., Ltd., "TK-1000") with an average polymerization degree of 1000, 4 parts by mass of Ca-Zn-based stabilizer (manufactured by Nitto Kasei Kogyo Co., Ltd., "HT-547A"), As a lubricant, 0.5 parts by mass of ester lubricant (manufactured by Emery Oleo Chemicals Japan Co., Ltd., "LOXIOL VPN963"), 0.5 parts by mass of ester lubricant (manufactured by Emery Oleo Chemicals Japan Co., Ltd., "LOXIOL G60"), filler 5 parts by mass of calcium carbonate (manufactured by Shiraishi Kogyo Co., Ltd., "μ-POWDER 3S") and 4.5 parts by mass of titanium oxide (manufactured by Ishihara Sangyo Co., Ltd., "R-830") were mixed with a Henschel mixer and 110. The temperature was raised to ° C. to obtain a vinyl chloride resin composition.

(Example 1)
(Manufacturing of processing aids)
115 parts by mass of ion-exchanged water was charged in a reaction vessel equipped with a stirrer and a recirculation cooler, and 0.1 part by mass of anhydrous sodium carbonate, 54.5 parts by mass of methyl methacrylate (MMA), and -n-butyl acrylate (BA) were charged therein. ) 30 parts by mass was added, and the inside of the reaction vessel was replaced with nitrogen. Then, 1.7 parts by mass of sodium alkyldiphenyl ether disulfonate (manufactured by Kao Co., Ltd., "Perex SS-L") was added as an emulsifier, the temperature of the reaction vessel was raised to 50 ° C. under stirring, and persulfate was used as a polymerization initiator. 0.13 parts by mass of potassium was charged, the polymerization reaction was started, and the mixture was heated and stirred for 4 hours to complete the polymerization, and an emulsion containing the polymer A was obtained.
The obtained emulsion was heated to 80 ° C., and 0.04 parts by mass of potassium persulfate was added. Then, a mixed solution of 15.5 parts by mass of methyl methacrylate (MMA) and 0.008 parts by mass of octyl mercaptan was added dropwise over 30 minutes, and after the addition, the mixture was held for 1 hour to form an emulsion containing polymer A and polymer B. Got
The obtained emulsion was spray-dried under the condition that the inlet temperature of hot air was 135 ° C. to obtain a powder of a processing aid.
When the obtained processing aid was separated and the copolymerization composition and weight average molecular weight (Mw) were measured, the polymer having Mw = 4.6 million, MMA / BA = 65% by mass / 35% by mass, and Mw = 49 It was a processing aid containing a polymer of MMA = 100% by mass in a ratio of 85% by mass: 15% by mass.

(Evaluation of processing aids and resin compositions)
The blocking resistance of the obtained processing aid powder was evaluated by the above-mentioned method for evaluating the blocking resistance of the processing aid. Further, 1 part by mass of the obtained processing aid was added to 114.5 parts by mass of the vinyl chloride resin composition obtained in Production Example 1 to evaluate the gelling characteristics. Further, 7 parts by mass of the obtained processing aid was added to 114.5 parts by mass of the vinyl chloride resin composition obtained in Production Example 1 to evaluate the melt tension. These results are shown in Table 1.

(Examples 2 to 12, Comparative Examples 1 to 4)
In the same manner as in Example 1, the processability was measured by measuring the gelling property and the melt tension, and the powder fluidity was measured by the blocking resistance test, except that the composition and molecular weight of the polymer were changed as shown in Table 1. Evaluation was performed. The results are shown in Table 1. In Table 1, "AN" is acrylonitrile, "St" are styrene, "BMA" represents butyl methacrylate, "k" a weight average molecular weight (Mw) shows the 10 ^3.

From the results in Table 1, the processing aids and resin compositions obtained in Examples 1 to 12 have a blocking resistance of "○" and a gelling property value of 700 sec or less, and further. Since the melt tension is 0.22 N or more, the melt tension is high, the gelation time is short, the workability is good, and the powder fluidity is good and the blocking resistance is excellent. Was shown to have.

Claims (11)

Processing assistance containing polymer A having a weight average molecular weight of 2 million or more and a glass transition temperature of 50 ° C. or lower, and polymer B having a weight average molecular weight of 1.5 million or less and a glass transition temperature of 70 ° C. or higher. A processing aid that contains more of the polymer A than the polymer B. The processing aid according to claim 1, wherein the polymer A contains at least one unit of an alkyl (meth) acrylate having an alkyl group having two or more carbon atoms as a constituent unit. Claim 1 or claim that the constituent unit of the polymer B includes one or more units selected from the group consisting of methyl (meth) acrylate, a copolymer of aromatic vinyl and vinyl nitrile, and a vinyl halide. Item 2. The processing aid according to Item 2. The ratio of the polymer A to 100% by mass of the total mass of the polymer A and the polymer B is 55% by mass or more and 99% by mass or less, and the ratio of the polymer B is 1% by mass or more and 45% by mass or less. The processing aid according to any one of claims 1 to 3. The ratio of one or more alkyl (meth) acrylate units having an alkyl group having two or more carbon atoms to all the constituent units constituting the polymer A is 20% by mass or more and 100% by mass or less, and methyl (meth). The processing aid according to any one of claims 1 to 4, wherein the total ratio of the units of the acrylate, the copolymer of aromatic vinyl and vinyl nitrile, and the vinyl halide is 0% by mass or more and 80% by mass or less. .. The ratio of one or more alkyl (meth) acrylate units having an alkyl group having two or more carbon atoms to all the constituent units constituting the polymer B is 0% by mass or more and 45% by mass or less, and methyl (meth). The processing aid according to any one of claims 1 to 5, wherein the total ratio of the units of the acrylate, the copolymer of aromatic vinyl and vinyl nitrile, and the vinyl halide is 55% by mass or more and 100% by mass or less. .. The processing aid according to any one of claims 1 to 6, wherein the ratio of the unit of methyl methacrylate to all the structural units of the polymer A is 1% by mass or more and 80% by mass or less. The processing aid according to any one of claims 1 to 7, wherein the ratio of the unit of methyl methacrylate to all the structural units of the polymer B is 65% by mass or more and 100% by mass or less. Polymer A having a weight average molecular weight of 2 million or more and a glass transition temperature of 50 ° C. or less, polymer B having a weight average molecular weight of 1.5 million or less and a glass transition temperature of 70 ° C. or more, a matrix resin, and the like. A resin composition containing the above polymer A in a larger amount than the polymer B. The resin composition according to claim 9, wherein the total ratio of the polymer A and the polymer B to 100 parts by mass of the matrix resin is 0.1 part by mass or more and 30 parts by mass or less. The resin composition according to claim 9 or 10, wherein the matrix resin is a vinyl chloride resin.