JP2006182840A - Styrene resin composition and molded product using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a styrene resin composition that can give molded products occurring an extremely reduced amount of VOC without large adverse effects to the excellent moldability, physical and mechanical properties characteristic in styrene resin. <P>SOLUTION: The styrene resin composition comprises (A) 100 pts.wt. of a styrene resin and (B) 0.1 to 10 pts.wt. of a hydrophobic zeolite. The resin composition is molded to give molded products. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a styrenic resin composition and a molded product formed by molding the same. More specifically, a volatile organic gas (hereinafter abbreviated as VOC (Volatile Organic Chemicals)) generated from a molded article made of the styrenic resin composition without significantly impairing the moldability, physical properties and mechanical properties of the styrene resin composition. Relates to a styrene-based resin composition having a very low value.

  Styrene resins are widely used in various fields such as automobiles, office equipment, and electrical / electronic equipment as general-purpose plastics because they are excellent in moldability, mechanical properties, thermal stability, and the like.

Particularly in the automotive field, styrene resins are often used in automobile interior parts, but VOCs (particularly compounds such as styrene, toluene, and benzene) emitted from the interior parts have an effect on the human body. It is pointed out that there is a possibility of giving a VOC, and various measures are being taken to reduce the VOC.

In the fields of office equipment, electrical / electronic equipment, etc., these styrene resins have been actively used in recent years as materials for housings and interior / exterior parts of computers, printers, copiers, fax machines and the like.

However, with the rapid spread of these office equipment, electrical / electronic equipment, etc., it is said that VOCs emitted from the plastic materials that make up these equipment may affect the human body, and countermeasures are suddenly taken. It is peeling.

On the other hand, zeolite is used as a deodorant from the viewpoint of removing odor components. (Patent Documents 1 and 2) However, there is no disclosure or suggestion about removal of VOCs (particularly compounds such as styrene, toluene, benzene) generated from molded articles in applications such as automobiles, office equipment, and electrical / electronic equipment. It is not.
Japanese Patent Application Laid-Open No. 07-227940 JP 07-316342 A

  The present invention provides a styrenic resin composition characterized in that the VOC generated from a molded product comprising the styrenic resin composition is extremely low without significantly degrading the moldability, physical properties, mechanical properties and the like that are characteristic of the styrenic resin composition. Is to provide.

  As a result of intensive research in order to solve such problems, the present inventor has formed a composition obtained by molding the composition by using a styrene resin composition in which a specific amount of a specific zeolite is blended with a styrene resin. It was found that VOC generated from the product was suppressed to a very low level, and the present invention was completed.

  That is, the present invention provides a styrene resin composition comprising 100 parts by weight of a styrene resin (A) and 0.1 to 10 parts by weight of a hydrophobic zeolite (B), and a molded product formed by molding the same. It is.

  The styrenic resin composition of the present invention generates very little VOC and has an excellent balance of moldability, mechanical properties, etc., and is suitable for interior and exterior parts of automobile interior parts, office equipment, electrical / electronic equipment, etc. It can be suitably used as a material of the present invention, and the industrial utility value is extremely high.

  The styrene resin (A) used in the present invention includes 20 to 100% by weight of a monovinyl aromatic monomer such as styrene and α-methylstyrene, and a vinyl cyanide monomer such as acrylonitrile and methacrylonitrile. A monomer or a monomer mixture comprising 0 to 60% by weight of a polymer, and 0 to 50% by weight of other vinyl monomers such as maleimide and methyl (meth) acrylate copolymerizable therewith. Examples of the resulting polymer are listed. Examples of these polymers include polystyrene (PS) and acrylonitrile / styrene copolymer (AS resin).

  The styrene resin (A) may be modified with rubber. Examples of the rubber-modified styrene resin include high impact polystyrene (HIPS) in which styrene is polymerized on rubber such as polybutadiene, ABS resin in which acrylonitrile and styrene are polymerized on polybutadiene, and methyl methacrylate and styrene are polymerized on polybutadiene. MBS resin etc. are mentioned. These can be used alone or in combination of two or more. Moreover, you may use it, mixing with the styrene resin which is the said rubber | gum unmodified | denatured.

  The rubber content in the rubber-modified styrenic resin is, for example, 2 to 50% by weight, preferably 5 to 30% by weight, and more preferably 5 to 15% by weight. If the rubber ratio is less than 2% by weight, the impact resistance becomes insufficient, and if it exceeds 50% by weight, problems such as a decrease in thermal stability, a decrease in melt fluidity, generation of gel, and coloring occur. There is a case.

Specific examples of the rubber include a rubbery polymer containing polybutadiene, acrylate and / or methacrylate, styrene / butadiene / styrene rubber (SBS), styrene / butadiene rubber (SBR), butadiene / acrylic rubber, isoprene rubber, isoprene. -Styrene rubber, isoprene / acrylic rubber, ethylene / propylene rubber and the like. Of these, polybutadiene can be suitably used. The polybutadiene is a low cis polybutadiene (for example, containing 1 to 30 mol% of 1,2-vinyl bonds and 30 to 42 mol% of 1,4-cis bonds), or high cis polybutadiene (for example, 1, 2 vinyl bonds). Any of those having a vinyl bond of 20 mol% or less and 1,4-cis bond of 78 mol% or more may be used, or a mixture thereof.

  The styrene resin (A) has a melt index (MI) measured in accordance with JIS K7210 under the conditions of a temperature of 200 ° C. and a load of 5 kg, usually from 1 to 40 g / 10 minutes, preferably from 2 to 20 g. / 10 minutes can be used.

  Further, in the styrene resin (A), it is also possible to use an alloy of a polycarbonate resin (PC) and the above-mentioned rubber unmodified and / or rubber modified styrene resin. Examples of such alloys include PC / PS, PC / AS, PC / ABS, and the like.

As the hydrophobic zeolite (B) used in the present invention, high silica zeolite having a SiO ₂ / Al ₂ O ₃ molar ratio of 40 or more is preferably used. A more preferred SiO ₂ / Al ₂ O ₃ molar ratio is in the range of 100 to 1000. This is different from the usual hydrophilic zeolite having a SiO ₂ / Al ₂ O ₃ molar ratio of around 1 to 10, and since it has a large amount of SiO ₂ component, it causes a slight change in the composition and structure of the crystal and becomes hydrophobic. . As a result, water molecules are less likely to be adsorbed, and conversely, the affinity with organic substances increases. Thus, the hydrophobic zeolite exhibits a selective adsorption power for the organic matter in the gas phase and the liquid phase in the mixed system of water and the organic matter. As the hydrophobic zeolite, “Absents” manufactured by UOP in the United States, “ZSM-5” manufactured by Eka Nobel Acteborag, Sweden, “HSZ series” manufactured by Tosoh Corporation, and the like are commercially available. The maximum pore diameter of the hydrophobic zeolite is preferably about 5 to 8 mm. If it is less than 5 mm, it is smaller than the molecular diameter of the target VOC, so that they are not effectively adsorbed, and if it exceeds 8 cm, these substances may be easily desorbed.

  The compounding quantity of hydrophobic zeolite (B) is 0.1-10 weight part with respect to 100 weight part of styrene resin (A). If the blending amount is less than 0.1 parts by weight, the VOC adsorption / removal effect is poor, which is not preferable. Moreover, when a compounding quantity exceeds 10 weight part, not only the impact strength of a styrene-type resin composition will fall, but it will become disadvantageous also in cost, and economical efficiency will be impaired significantly. More preferably, it is in the range of 0.5 to 7.0 parts by weight, and more preferably 1.0 to 3.0 parts by weight.

  The method for mixing the styrenic resin (A) and the hydrophobic zeolite (B) is not particularly limited, and is mixed with an optional mixer such as a tumbler, ribbon blender, high-speed mixer, etc. It can be easily melt-kneaded with a machine or the like.

  When mixing, known additives, such as mold release agents, heat stabilizers (antioxidants), light stabilizers, UV absorbers, spreading agents (epoxidized soybean oil, liquid paraffin, etc.) as necessary Flame retardants, flame retardant aids, various elastic elastomers, fillers, antistatic agents, dyes and pigments, other thermoplastic resins such as polyethylene terephthalate, polybutylene terephthalate, amorphous polyester, polyphenylene Resins such as ether and polymethyl methacrylate can be blended as necessary.

  Examples of the filler include glass fiber, glass bead, glass flake, carbon fiber, talc, clay, mica, potassium titanate whisker, aluminum borate whisker, wollastonite, silica and the like.

  EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples. Unless otherwise specified, “parts” and “%” are based on weight.

The details of the compounding components used are as follows.
(A) Rubber reinforced styrene resin
Santac AT07 (bulk polymerized product) manufactured by A & L Japan (hereinafter abbreviated as ABS)
(B) Hydrophobic zeolite Hydrophobic zeolite manufactured by UOP, Inc. 3000 (adsorption pore diameter: 6 mm)
(Hereafter abbreviated as ZEO)

  Further, two types of VOC reduction rates were obtained from the data on the amount of VOC released per unit time: a styrene gas reduction rate and a styrene equivalent total VOC reduction rate. The measuring method of the amount of VOC emission per unit time is as follows.

(VOC emission)
After 0.1 g of pellets of the resin composition were heated at 80 ° C. for 1 hour in an inert gas stream, the out gas generated from the pellet samples was collected and concentrated with an adsorbent, and then per hour by GC-MS. The amount of VOC released was determined.
The used heat introduction apparatus and GC-MS are as follows.
Heating introduction device:
TurboMatrix ATD made by Perkin Elmer
GC-MS:
Made by Agilent Technologies
HP5973N / GC6890
Adsorbent:
Tenax GR manufactured by Chromatography Research
Quantitation limit:
10ng / g · hr

The amount of VOC released per unit time was calculated by dividing into the following two types.
Styrene gas release (ng / g · hr):
From the obtained outgas data, paying attention only to styrene as VOC
The amount released.
Styrene conversion total VOC release (ng / g · hr):
From the obtained outgas data, the release amount of all components was converted to styrene.
More calculated amount of release.

(VOC reduction rate calculation method and evaluation criteria)
Styrene gas reduction rate:
In each of the resin compositions, when a hydrophobic zeolite is blended, and
Using the pellet sample when not blended, determine the amount of styrene gas released
The styrene gas reduction rate was obtained from the following formula. The styrene gas reduction rate is
20% or more was accepted.
Styrene gas reduction rate (%) = (STY2-STY1) × 100 / STY2
STY1: Amount of styrene gas released from a sample containing hydrophobic zeolite
STY2: Styrene gas release amount of sample not containing hydrophobic zeolite Reduction rate of total VOC in terms of styrene:
In each of the resin compositions, when a hydrophobic zeolite is blended, and
Styrene conversion total VOC release using pellet sample when not blended
The amount was determined, and the total VOC reduction rate in terms of styrene was determined by the following formula. Still
The total VOC reduction rate converted to 30% or more was regarded as acceptable.
Reduction rate of total VOC in styrene (%)
= (ALL2-ALL1) x100 / ALL2
ALL1:
Total VOC release from styrene in samples containing hydrophobic zeolite
ALL2:
Total amount of VOC emission in styrene conversion of samples not containing hydrophobic zeolite

(Izod impact strength with notch)
Using pellets of various resin compositions shown in Table 1, a 3.2 mm thick Izod impact strength test piece was prepared under the condition of a melting temperature of 230 ° C. using a J100E-C5 injection molding machine manufactured by Nippon Steel Works. The notched Izod impact strength was measured at a measurement temperature of 23 ° C. in accordance with ASTM D256. An impact value of 6 kg / cm / cm or more was considered acceptable. The results are shown in Table 1.

Example 1
100 parts of ABS and 2 parts of ZEO are put into a tumbler at once, dry mixed for 10 minutes, and then kneaded at a melting temperature of 210 ° C. using a twin screw extruder (Kobe Steel KTX37), and pellets of the resin composition (Example 1) was obtained. When the VOC emission amount was also determined using the obtained pellets, the styrene gas emission amount and the styrene equivalent total VOC emission amount were 210 ng / g · hr and 1300 ng / g · hr, respectively.

(Comparative Example 1)
A pellet sample (Comparative Example 1) was obtained in the same manner as in Example 1 except that ZEO was not blended. When the obtained pellets were used to determine the VOC release amount, the styrene gas release amount and the styrene equivalent total VOC release amount were 280 ng / g · hr and 2000 ng / g · hr, respectively. Using the data, VOC reduction rates (styrene gas reduction rate and styrene equivalent total VOC reduction rate) of various resin compositions of Examples 1 to 3 and Comparative Examples 2 and 3 were calculated. The results are shown in Table 1.

(Examples 2 and 3, Comparative Examples 2 and 3)
Except changing the compounding quantity of ZEO to the quantity shown in Table 1, all the same operations as Example 1 were performed, and various pellets were obtained. When the VOC emission amount was also determined using the obtained pellets, the styrene gas emission amount and the styrene equivalent total VOC emission amount were as follows.
Styrene gas release amount Total VOC release amount in terms of styrene Example 2: 140 ng / g · hr 780 ng / g · hr
Example 3: 98 ng / g · hr 500 ng / g · hr
Comparative Example 2: 276 ng / g · hr 1940 ng / g · hr
Comparative Example 3: 56 ng / g · hr 240 ng / g · hr
Using the above data, VOC reduction rates (styrene gas reduction rate and styrene equivalent total VOC reduction rate) of various resin compositions were calculated. The results are shown in Table 1.

Table 1 Composition ratios and evaluation results of various resin compositions

判定： ○ 合格 × 不合格

Judgment: ○ Pass × Fail

  As shown in Table 1, when the structural requirements of the present invention were satisfied (Examples 1 to 3), the standards were satisfied over all evaluation items.

On the other hand, in the case where the constituent requirements of the present invention are not satisfied, each case has some drawbacks.
In Comparative Example 2, since the hydrophobic zeolite (B) component of the present invention was further less than the lower limit of the specified range, the VOC reduction rate of either the styrene gas reduction rate or the styrene conversion total VOC reduction rate did not satisfy the standard. .
In Comparative Example 3, since the hydrophobic zeolite (B) component of the present invention exceeds the upper limit of the specified range, the styrene gas reduction rate and the styrene equivalent total VOC reduction rate satisfy the standard, but the impact strength is the standard. I was not satisfied.

Claims (4)

  A styrene resin composition comprising 100 parts by weight of a styrene resin (A) and 0.1 to 10 parts by weight of a hydrophobic zeolite (B). The styrene resin is one or more selected from acrylonitrile / butadiene / styrene copolymer (ABS resin), polystyrene (PS), and acrylonitrile / styrene copolymer (AS resin). Item 5. A styrene resin composition according to Item 1.   The styrene resin composition according to claim 1, wherein the amount of the hydrophobic zeolite (B) is 1.0 to 3.0 parts by weight per 100 parts by weight of the styrene resin (A). The molded article formed by shape | molding the styrenic resin composition as described in any one of Claims 1-3.