JP2004210834A - Rubber-modified styrenic resin and its sheet - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To industrially favorably provide a rubber-modified styrenic resin which has a better balance between impact strength and transparency than before and gives a sheet with little soil, when molded and a sheet from the resin. <P>SOLUTION: The rubber-modified styrenic resin is a thermoplastic resin composition containing (X) a copolymer of a styrenic monomer unit and a (meth)acrylate monomer unit and (Y) a rubbery substance. The copolymer (X) forms a continuous phase and the rubbery substance forms a particle dispersed phase. The particle dispersed phase comprises (I) a dispersed particle with a number average particle diameter of 1.0-2.0 μm and (II) a dispersed particle with a number average particle diameter of 0.1-0.5 μm. The amount of the rubber component contained in the dispersed particle (I) is 0.2-3.5 mass% and in the dispersed particle (II) is 4-20 mass%. The rubber-modified styrenic resin which gives a sheet with little soil, when molded is constituted in a way that 4,000-8,000 ppm of a mercapto residue is contained in the rubber-modified styrenic resin in which the ratio of the weight average molecular weight to the number average molecular weight of the THF-soluble fraction of the thermoplastic resin is ≤ 2.5. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

【００３９】
【表２】

【００４０】
各物性値の測定方法は以下の通りである。
（１）全光線透過率、曇度：表１及び表２に示したものは、射出成形機（東芝機械社製ＩＳ−５０ＥＰＮ）を用いて、シリンダー温度２２０℃で厚さ１ｍｍ、２ｍｍ、３ｍｍの３段プレートを成形した。この３段プレートの厚さ２ｍｍ部を用いて、ＡＳＴＭ Ｄ−１００３に準じて、ＨＡＺＥメーター（日本電色工業社製ＮＤＨ−１００１ＤＰ）を用いて測定した。
また、表１及び表２のシート成形品物性に示したものは、得られたシートを用いて、ＡＳＴＭ Ｄ−１００３に準じて、ＨＡＺＥメーター（日本電色工業社製ＮＤＨ−１００１ＤＰ）を用いて測定した。
【００４１】
（２）シャルピー衝撃強度：東芝機械社製（ＩＳ−８０ＣＶＮ）を用いて、シリンダー温度２２０℃で、１２．７×６４×６．４ｍｍ寸法の試験片を成形した。この試験片を用いて、ＩＳＯ１７９−２に準じて測定した。
【００４２】
（３）折り曲げ試験：シート押出によって作成したサンプルシートを引き取り方向、反引き取り方向の２方向に折り曲げを行い、シートの割れの発生を目視観察した。
○：良好（割れなし）
×：不良（割れあり）
また、表１及び表２のシート加工時汚染開始時間とは、シート加工時でシートの汚染が始まる時間のことをいう。例えば、表１の実施例１のシート加工時汚染開始時間が１０時間とは、シート加工を始めてから１０時間後にシートの汚染が始まる意味である。シートの汚染とは、前述のように樹脂組成物を押出し機にてシート加工すると、押出し機のシリンダー内やダイス（吐出口）等に付着した樹脂が熱履歴を受け、シートが変色したり、シート表面を汚染してシートの商品価値を低下させることをいう。
【００４３】
【発明の効果】
本発明により、従来にない衝撃強度、及び透明性のバランスに優れた、シート加工時にシートの汚染が少ないゴム変性スチレン系樹脂及びそのシートを工業上極めて有利に提供することができる。本発明のゴム変性スチレン系樹脂及びそのシートは、衝撃強度、透明性に優れていることより、特にフレネルレンズやレンチキュラーレンズ等の光学用途に好適に用いることができる。[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a rubber-modified styrenic resin which causes less sheet contamination during sheet extrusion and a sheet thereof.
[0002]
[Prior art]
Conventionally, a copolymer comprising a copolymer of a styrene-based monomer and a (meth) acrylate-based monomer has been known. However, when a sheet is extruded by an extruder, a die of the extruder (a discharge port) is formed. ), Etc., the resin easily adheres, and the resin receives a heat history, and there is a problem that the sheet is discolored or the sheet surface is contaminated to lower the commercial value. Further, in order to solve this problem, it is necessary to appropriately clean the dice, which has a disadvantage that productivity is remarkably reduced and economic efficiency is poor.
[0003]
As a method for preventing the resin from adhering to the die, there is a report that sharpening of the edge by WC coating on the die is effective (see Non-Patent Document 1). However, there is a disadvantage that the resin adheres again due to abrasion of the edge portion after long use. Further, a technique for preventing the resin from adhering to a die by improving the resin has not been found yet.
[0004]
[Non-patent document 1]
Takeshi Kawabe, "Convertec" Published by Processing Technology Research Group, December 2001 issue, p. 24
[0005]
[Problems to be solved by the invention]
An object of the present invention is to provide a rubber-modified styrenic resin containing a styrene-methacrylic acid ester-based copolymer which has excellent transparency and causes less contamination of the sheet during sheet extrusion, and a sheet thereof.
[0006]
[Means for Solving the Problems]
The present inventors have conducted intensive studies to solve the above problems, and as a result, identified a mercapto residue in a copolymer containing styrene-based monomer units and (meth) acrylate-based monomer units as main components. It has been found that this problem is satisfied by the presence of a large amount, and the present invention has been completed.
[0007]
That is, the present invention provides (1) a thermoplastic resin containing a copolymer (X) comprising a styrene monomer unit and a (meth) acrylate monomer unit and a rubbery substance (Y). In the composition, the copolymer (X) forms a continuous phase, the rubber-like substance (Y) forms a particulate dispersed phase, and the particulate dispersed phase (hereinafter, referred to as dispersed particles) is a number. Dispersed particles (I) having an average particle diameter of 1.0 to 2.0 μm and dispersed particles (II) having a number average particle diameter of 0.1 to 0.5 μm are included in the dispersed particles (I). The rubber component amount is 0.2 to 3.5% by mass, the rubber component amount in the dispersed particles (II) is 4 to 20% by mass, and the weight-average molecular weight and the number of the THF-soluble components of the thermoplastic resin. In a rubber-modified styrenic copolymer having an average molecular weight ratio of 2.5 or less, a mercapto residue is added to the rubber in an amount of 4000 to 80. A rubber-modified styrene-based resin containing 00 ppm and having less sheet contamination during sheet extrusion, and a sheet made of the rubber-modified styrene-based resin described in (2) and (1), which has less sheet contamination during extrusion.
[0008]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, the present invention will be described in detail.
Examples of the styrene-based monomer used in the present invention include styrene, α-methylstyrene, p-methylstyrene, pt-butylstyrene, and the like, with styrene being preferred. These may be used alone or in combination of two or more.
[0009]
Examples of the (meth) acrylate monomer used in the present invention include methyl methacrylate, ethyl methacrylate, methyl acrylate, ethyl acrylate, n-butyl acrylate, 2-methylhexyl acrylate, 2-ethylhexyl acrylate, and octyl acrylate. No. These may be used alone or in combination of two or more. Preferably, it is methyl methacrylate, ethyl acrylate, n-butyl acrylate or a mixture thereof.
[0010]
Further, if necessary, other copolymerizable monomers such as acrylonitrile can be used.
[0011]
As the rubbery substance forming the dispersed phase, polybutadiene, styrene-butadiene random copolymer, styrene-butadiene block copolymer and the like can be used. A styrene-butadiene random copolymer and a styrene-butadiene block copolymer can be suitably used in the sense that the refractive index is easily matched with that of the continuous phase copolymer. These may be used alone or in combination of two or more.
[0012]
The dispersed particles contained in the thermoplastic resin composition of the present invention have a dispersed particle (I) having a number average particle size of 1.0 to 2.0 μm and a number average particle size of 0.1 to 0.5 μm. And dispersed particles (II).
[0013]
The number average particle diameter of the dispersed particles (I) is 1.0 to 2.0 μm. Preferably it is 1.2 to 1.8 μm. If it is less than 1.0 μm, the impact strength decreases. If it exceeds 2.0 μm, the total light transmittance is reduced and the light diffusivity is reduced.
[0014]
The number average particle diameter of the dispersed particles (II) is from 0.1 to 0.5 μm. Preferably it is 0.15 to 0.45 μm. If it is less than 0.1 μm, the impact strength will be reduced. If it exceeds 0.5 μm, the total light transmittance is reduced and the light diffusivity is reduced.
[0015]
The amount of the rubber component contained in the dispersed particles (I) in the thermoplastic resin composition of the present invention is 0.2 to 3.5% by mass. Preferably it is 0.3 to 3% by mass. If it is less than 0.2% by mass, the impact strength is reduced. If it exceeds 3.5% by mass, the total light transmittance is reduced and the light diffusivity is reduced.
[0016]
The amount of the rubber component contained in the dispersed particles (II) in the thermoplastic resin composition of the present invention is 4 to 20% by mass. Preferably it is 6 to 18% by mass. If it is less than 4% by mass, the impact strength is reduced. If it exceeds 18% by mass, the total light transmittance decreases and the light diffusivity decreases.
[0017]
The number average particle size of the dispersed particles was determined by using a solution obtained by stirring 1 g of the thermoplastic resin composition in 100 ml of N, N-dimethylformamide for 24 hours using a laser diffraction / scattering particle size distribution analyzer LS230 (Beckman Coulter, Inc.). Was used for the measurement. The rubber component amount indicates the polybutadiene amount measured by a halogen addition method.
[0018]
Further, as the compound having a mercapto group used in the present invention, n-butyl mercaptan, isobutyl mercaptan, n-hexyl mercaptan, n-octyl mercaptan, n-decyl mercaptan, n-dodecyl mercaptan, sec-dodecyl mercaptan, tert- Alkyl groups such as dodecyl mercaptan, primary, secondary and tertiary mercaptans having substituted alkyl groups, aromatic mercaptans such as phenylmercaptan, thiocresol, thioglycolic acid and its esters, and ethylenethioglycol. . These may be used alone or in combination of two or more.
Preferably, it is n-dodecyl mercaptan, t-dodecyl mercaptan, or a mixture thereof.
[0019]
The mercapto residue contained in the rubber-modified styrenic resin of the present invention is 10 to 8000 ppm, preferably 4000 to 8000 ppm, in the rubber-modified copolymer.
When the mercapto residue is 10 ppm or less, sheet contamination occurs during sheet extrusion, and when it exceeds 8000 ppm, sheet extrusion becomes unstable.
[0020]
The ratio (Mw / Mn) of the weight average molecular weight (Mw) to the number average molecular weight (Mn) of the THF-soluble component of the rubber-modified styrene resin of the present invention must be 2.5 or less. If it exceeds 2.5, the strength is reduced, and the sheet is broken at the time of winding the sheet. Both the weight average molecular weight Mw and the number average molecular weight Mn were measured by the following gel permeation chromatography (GPC) method.
Apparatus name: SYSTEM-21 Shodex (manufactured by Showa Denko KK)
Column: 3 pieces of PL gel MIXED-B Series temperature: 40 ° C
Detection: Differential refractive index solvent: THF (tetrahydrofuran)
Concentration: 2% by mass
Calibration curve: Prepared using standard polystyrene (PS) (manufactured by PL), and the weight average molecular weight Mw and the number average molecular weight Mn were expressed in terms of PS.
[0021]
Quantification of sulfur derived from a mercapto residue contained in the rubber-modified styrene resin of the present invention was performed by the following operation.
1 g of the rubber-modified styrene resin was dissolved in 100 ml of MEK at 25 ° C. for 24 hours, and centrifuged at a temperature of 10 ° C. and a rotation speed of 8,500 rpm for 15 minutes using a centrifuge CR26H manufactured by Hitachi Koki Co., Ltd.
Next, the insoluble matter was dried with a vacuum dryer at 60 ° C. for 24 hours.
Thereafter, 250 mg of the dried insoluble matter was taken out, burned under the following conditions, and the sulfate ion absorbed in the obtained absorbing solution was quantitatively analyzed by ion chromatography and converted to the amount of sulfur.
<Combustion conditions>
Apparatus name: Sample combustion apparatus QF-02 type (manufactured by Dia Instruments)
Carrier gas: Air / O ₂ 100 ml / min Switch from Air to O ₂ at 700 ° C., and burn the sample completely.
Absorbing liquid: 0.3% hydrogen peroxide burning time: 60 minutes
The method for producing the rubber-modified styrene-based resin of the present invention is not particularly limited, but a copolymer comprising a styrene-based monomer unit and a (meth) acrylate-based monomer unit and containing no dispersed particles [hereinafter referred to as “ , Copolymer (A)], a styrene-based monomer unit and a (meth) acrylate-based monomer unit, and having a number average particle diameter of 1.0 to 2.0 μm. A copolymer containing particles (I) [hereinafter referred to as a copolymer (B)], and a copolymer comprising a styrene-based monomer unit and a (meth) acrylate-based monomer unit, and A method containing separately preparing particles (hereinafter, referred to as a copolymer (C)) containing dispersed particles (II) having a diameter of 0.1 to 0.5 μm and mixing them to obtain a thermoplastic resin is disclosed in US Pat. Is advantageous in that it is easy to distribute You.
The compound having a mercapto group is preferably added at the time of polymerization of the copolymer (A), at the time of polymerization of the copolymer (B), or at the time of polymerization of the copolymer (C). May be added at the time of polymerization, or may be added at the time of polymerization of a plurality of copolymers.
[0023]
The production of the rubber-modified styrenic resin is not particularly limited, but a bulk polymerization method, a suspension polymerization method, a solution polymerization method, and an emulsion polymerization method can be suitably employed.
[0024]
The rubber-modified styrenic resin of the present invention may optionally contain additives. For example, a plasticizer, a lubricant, silicone oil, or the like can be blended in order to improve fluidity and mold release properties. Further, an antistatic agent can be blended for dust prevention of the molded product. In order to impart heat resistance, a heat stabilizer can be added. In order to impart light resistance, a light stabilizer or an ultraviolet absorber can be added. However, if an ultraviolet curing agent is applied to the surface of a molded article and then cured by ultraviolet light, care must be taken as this will affect the curing. is necessary. In addition, a coloring agent and the like can be blended.
[0025]
【Example】
Hereinafter, the present invention will be described specifically with reference to Examples, but the present invention is not limited to these Examples. In the examples, all parts and percentages are expressed on a mass basis.
[0026]
Production of copolymer (A) 42.5 parts of styrene and 57.5 parts of methyl methacrylate (MMA) in an autoclave equipped with a stirrer, 0.2 parts of benzoyl peroxide as a polymerization initiator, and t-dodecyl as a compound having a mercapto group 0.1 part of mercaptan, 0.001 part of sodium dodecylbenzenesulfonate and 0.5 part of tribasic calcium phosphate as a suspension stabilizer, and 200 parts of pure water were charged, and the mixture was heated at a temperature of 95 ° C for 6 hours and further at a temperature of 130 ° C. Polymerized for 2 hours. After completion of the reaction, washing, dehydration and drying were performed to obtain a bead-like copolymer (A1). The weight average molecular weight in terms of polystyrene of the copolymer (A1) measured by the GPC method was 145,000. The composition was styrene / MMA = 43.0 / 57.0.
[0027]
Polymerization was carried out in the same manner as in the production of the copolymer (A1), except that the compound having a mercapto group was not used, to obtain a copolymer (A2). The weight average molecular weight of the copolymer (A2) was 167,000.
[0028]
Polymerization was carried out in the same manner as in the preparation of the copolymer (A1), except that 0.5% of t-dodecylmercaptan was added as a compound having a mercapto group, to obtain a copolymer (A3). The weight average molecular weight of the copolymer (A3) was 127,000.
[0029]
Production of copolymer (B) In an autoclave equipped with a stirrer, 42.5 parts of styrene and 57.5 parts of methyl methacrylate, styrene-butadiene copolymer rubber (styrene content 25%, "Tuffden 2000" (trade name) manufactured by Asahi Kasei Kogyo Co., Ltd.) After adding 5 parts and stirring at room temperature for 3 hours, 0.04 part of benzoyl peroxide as a polymerization initiator and 0.2 part of t-dodecyl mercaptan as a compound having a mercapto group were added, and the mixture was stirred at a stirring speed of 200 rpm. At the same time, bulk polymerization was carried out at a temperature of 90 ° C. to a polymerization conversion rate of 30%. Then, 0.2 part of dicumyl peroxide as a polymerization initiator, 0.001 part of sodium dodecylbenzenesulfonate and 0.5 part of tribasic calcium phosphate as suspension stabilizers, and 200 parts of pure water were added. Polymerization was carried out at 115 ° C. for 1.5 hours and at 130 ° C. for 2.5 hours. After completion of the reaction, washing, dehydration and drying were performed to obtain a bead-like copolymer (B1). The rubber component amount of the copolymer (B1) was 3.7%. The rubber-like substance formed a particulate dispersed phase, and the number-average particle diameter of the dispersed particles was 1.4 μm. The weight average molecular weight was 129,000.
[0030]
In the same manner as in the production of the copolymer (B1), the copolymer (B2) having dispersed particles having a number average particle diameter of 0.8 μm and 2.5 μm (B3) having dispersed particles of the above was obtained.
[0031]
Polymerization was carried out in the same manner as described above except that the production of the copolymer (B1) and addition of 0.3 part of t-dodecylmercaptan as a compound having a mercapto group gave a copolymer (B4).
The weight average molecular weight of the copolymer (B4) was 103,000. The number average particle diameter of the dispersed particles was 1.4 μm.
[0032]
Polymerization was carried out in the same manner as in the production of the copolymer (B1), except that t-dodecylmercaptan was not added as the compound having a mercapto group, to obtain a copolymer (B5).
The weight average molecular weight of the copolymer (B5) was 153,000. The number average particle diameter of the dispersed particles was 1.4 μm.
[0033]
Production of copolymer (C) In an autoclave equipped with a stirrer, 49 parts of butadiene, 16 parts of styrene, 150 parts of pure water, 0.5 part of potassium oleate, 0.13 part of t-butyl hydroperoxide, 0.03 part of Rongalite , 0.002 part of ferrous sulfate, 0.003 part of ethylenediaminetetraacetic acid sodium salt, 0.1 part of sodium pyrophosphate, and 1.0 part of t-dodecylmercaptan, and polymerization was carried out at 45 ° C. for 17 hours. The number average particle diameter of the obtained styrene-butadiene rubber latex was 0.08 μm.
The latex was stabilized by adding 0.005 parts of sodium sulfosuccinate. By adding an aqueous solution of hydrogen chloride to this latex with stirring, the latex particles were coagulated and enlarged, and a rubber latex having a number average particle diameter of 0.2 μm was obtained. To this latex, 16 parts of styrene, 17 parts of MMA, 2 parts of n-butyl acrylate, 0.04 part of divinylbenzene, and 0.08 part of t-butyl hydroperoxide were added, and polymerized at a temperature of 60 ° C. for 6 hours. After adding 0.5 part of t-butylphenol and 0.5 part of dilauryl thiopropionate to this latex, a copolymer was precipitated with hydrochloric acid, neutralized, washed, dehydrated and dried to obtain a powdery copolymer. (C1) was obtained.
The rubber component amount of this copolymer (C1) was 48.0%.
[0034]
In the same manner as in the production of the copolymer (C1), by changing only the aggregation conditions of the rubber latex, the copolymer (C2) having dispersed particles having a number average particle diameter of 0.08 μm and 0.6 μm A copolymer (C3) having dispersed particles was obtained.
[0035]
Except that the addition amount of t-dodecyl mercaptan as a compound having a mercapto group is changed to 0.05%, dispersed particles having a number average particle diameter of 0.2 μm are produced in the same manner as in the production of the copolymer (C1). (C4) having the following formula:
[0036]
Except that the addition amount of t-dodecyl mercaptan as a compound having a mercapto group is changed to 0.01%, dispersed particles having a number average particle diameter of 0.2 μm are produced in the same manner as in the production of the copolymer (C1). (C5) having the following formula was obtained.
[0037]
Reference Examples 1-4, Examples 1-2, Comparative Examples 1-10
The copolymers (A), (B) and (C) were mixed at the mixing ratios shown in Tables 1 and 2 and kneaded in a 40 mm diameter single screw extruder at a temperature of 240 ° C. and a screw rotation speed of 100 rpm. Then, pelletization was performed to obtain pellets.
GPC of the composition was measured using the pellets. The pellets were injection molded at a temperature of 220 ° C. to obtain test pieces. Various physical properties were measured using this test piece.
Further, a sheet was formed at a cylinder temperature of 230 ° C. by a T-die type extruder. The measured physical properties are shown in Tables 1 and 2.
Tables 1 and 2 show the physical properties, transparency, and contamination start time of the obtained sheet during sheet processing.
[0038]
[Table 1]

[0039]
[Table 2]

[0040]
The measuring method of each physical property value is as follows.
(1) Total light transmittance and haze: those shown in Tables 1 and 2 were measured using an injection molding machine (IS-50 EPN manufactured by Toshiba Machine Co., Ltd.) at a cylinder temperature of 220 ° C. and a thickness of 1 mm, 2 mm, and 3 mm. Was molded. Using a 2-mm-thick portion of the three-stage plate, a measurement was performed using a Haze meter (NDH-1001DP manufactured by Nippon Denshoku Industries Co., Ltd.) according to ASTM D-1003.
Moreover, what was shown in the sheet | seat molded article physical property of Table 1 and Table 2 using the obtained sheet | seat and according to ASTM D-1003 using the Haze meter (Nippon Denshoku Industries Co., Ltd. NDH-1001DP). It was measured.
[0041]
(2) Charpy impact strength: A test piece having a size of 12.7 × 64 × 6.4 mm was formed at a cylinder temperature of 220 ° C. using Toshiba Machine Co., Ltd. (IS-80CVN). Using this test piece, measurement was performed according to ISO179-2.
[0042]
(3) Bending test: The sample sheet produced by sheet extrusion was bent in two directions, a take-off direction and a counter-take-off direction, and the occurrence of cracks in the sheet was visually observed.
：: good (no crack)
×: defective (with cracks)
Further, the contamination start time during sheet processing in Tables 1 and 2 refers to the time when sheet contamination starts during sheet processing. For example, the start time of sheet processing contamination of Example 1 in Table 1 of 10 hours means that sheet contamination starts 10 hours after the start of sheet processing. Sheet contamination means that when the resin composition is processed into a sheet by an extruder as described above, the resin adhering to the inside of the cylinder of the extruder or a die (discharge port) receives a heat history, and the sheet is discolored. It means that the sheet surface is contaminated and the commercial value of the sheet is reduced.
[0043]
【The invention's effect】
Industrial Applicability According to the present invention, a rubber-modified styrenic resin having excellent unprecedented balance of impact strength and transparency and less contamination of a sheet during sheet processing and a sheet thereof can be provided industrially extremely advantageously. The rubber-modified styrenic resin and sheet thereof of the present invention are excellent in impact strength and transparency, and thus can be suitably used particularly for optical applications such as Fresnel lenses and lenticular lenses.

Claims (2)

A thermoplastic resin composition comprising a copolymer (X) comprising a styrene-based monomer unit and a (meth) acrylate-based monomer unit and a rubbery substance (Y), wherein the copolymer (X) forms a continuous phase, the rubbery substance (Y) forms a particulate dispersed phase, and the particulate dispersed phase [hereinafter referred to as dispersed particles] has a number average particle diameter of 1.0 to 2; The dispersed particles (I) having a particle size of 0.1 μm and the dispersed particles (II) having a number average particle size of 0.1 to 0.5 μm, and the rubber component amount contained in the dispersed particles (I) is 0.2 to 3 0.5% by mass, the amount of the rubber component contained in the dispersed particles (II) is 4 to 20% by mass, and the ratio of the weight average molecular weight to the number average molecular weight of the THF-soluble portion of the thermoplastic resin is 2.5 or less. The rubber-modified styrenic copolymer having a mercapto residue content of 4000 to 8000 ppm. Rubber-modified styrenic resin that minimizes sheet contamination during extrusion. A sheet which is less contaminated when extruding a sheet comprising the rubber-modified styrene resin according to claim 1.