JPS62240331A - Drawn styrene resin sheet - Google Patents

Abstract

PURPOSE:To obtain the titled drawn sheet having excellent transparency, uniform applicability of silicone oil, peelability of the sheet and releasability of stacked articles, by biaxially drawing a resin composition composed of a styrene resin having decreased rubber concentration and synthetic silicon dioxide. CONSTITUTION:The objective drawn sheet having improved applicability of a silicone oil by the minute irregularity formed on the surface of a styrene resin sheet and avoiding the defective appearance and rupture of the sheet is produced by biaxially drawing a resin composition composed of (A) a transparent styrene resin containing 0.01-0.05wt% styrene-grafted diene rubber (in terms of rubber concentration) having an average particle diameter of 1-5mum and (B) 30-300ppm of synthetic silicon dioxide having an average particle diameter of 1-5mum.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Application) This invention relates to a styrenic resin stretched sheet that has good peelability in one piece and in stacked molded products.

(Conventional technology) '2111! Stretched styrenic resin sheets are widely used in the food packaging field because of their transparency and warmth. However, this biaxially stretched sheet has a strong blocking property, and also has the disadvantage that containers obtained from the sheet are difficult to peel off during use when stacked.

A method to improve this drawback is to add rubber to the styrene resin and when the sheet metal is biaxially stretched, make the rubber protrude from the surface of the sheet to improve sheet peeling (especially (Japanese Patent Application Laid-Open No. 50-74649) and applying Clicquot/Oil T- to the surface of the sheet (Japanese Patent Application Laid-open No. 52-7464)
-8080) has been proposed.

However, when rubber-added resin is stretched biaxially, the im becomes flat, so it is difficult to maintain a constant proportion of the im to protrude from the sheet surface, and it is necessary to add a large amount of im to improve the sheet peeling. If too much rubber is used, foreign substances may be generated due to long-term operation and discoloration due to the addition of recycled products.
There are drawbacks that cause poor sheet appearance and sheet breakage.

It is also possible to further reduce the rubber mass and increase the particle size of the rubber, for example to about 6 to 10 μm, but this method causes roughening of the surface of the biaxially stretched sheet and a decrease in gloss.
O cannot be used in practice (Problems to be solved by the invention) In order to solve all of these drawbacks, the present invention provides a resin composition t-2 of styrene resin and synthetic silicon dioxide with a reduced rubber concentration. By stretching, the synthetic silicon dioxide is not stretched flat during stretching, so it uniformly creates fine irregularities on the surface of the styrene resin sheet, improving the performance of the silicone oil layer and minimizing the yellowing of the rubber due to thermal deterioration. To avoid poor appearance and sheet breakage, further weaken the blocking property between stretched sheets, and improve peeling of a molded product punched from a large number of sheets, thereby completing a stretched styrene resin sheet. A circle that leads to.

(Means for Solving the Problems) That is, the present invention provides a transparent styrenic resin containing 0.01 to 0.05% by weight of styrene-grafted zoencopies with an average particle size of 1 to 5 μm in rubber concentration; 30-300 pμm in resin
It is characterized in that it is formed by biaxially stretching a resin composition made of impregnated synthetic silicon dioxide having an average particle diameter of 1 to 5 μm.

Examples of the styrenic monomer of the transparent styrenic resin containing styrene rubber used in the present invention include styrene, aralkyl styrene (fc, 0-lm-
and p-methylstyrene, -ethylstyrene, -isopropylstyrene, -methylstyrene, -tertiary-butylstyrene), various alpha-alkylstyrenes (e.g. methylstyrene, ethylstyrene), various (in D'7) 10 styrene V7 (e.g., thao+, m-oyohyp-chlorostyrene, bromostyrene, fluorostyrene),
Various di-, tri-, tetra- and penta-substituted chlorostyrenes, bromostyrenes and fluorostyrenes 2 and various alpha- and beta-chlorostyrenes (e.g. alpha-chlorostyrene, alpha-bromostyrene, beta-chlorostyrene and beta-promosterene)'
j? and acrylonitrile 1 methyl methacrylate, etc., which can be copolymerized with the above monomers.

In addition, diene rubbers include, for example, conjugated 1,3-dienes, such as butadiene, imprene, 2-chloro-1,5-J''tasoene, 1-chloro-1
, 3-butadiene, piperylene, and the like.

The styrene graft-containing styrenic resin of the present invention can be obtained by, for example, polymerizing a diene rubber on a styrene monomer, and adding 2 to 1 ON of diene rubber f.
Either method may be used in which a graft-type rubber-modified styrene resin containing a certain amount of rubber and a transparent styrene resin are arbitrarily mixed.

Furthermore, the average particle diameter of the styrene-grafted diene rubber used in the present invention is preferably 1 to 5 μm; if it is less than 1 μm, the rubber protrusions that protrude from the sheet surface when the sheet is biaxially stretched are too small, weakening the blocking properties of the sheet. If it exceeds 5 .mu.m, the surface of the sheet will become rough and the gloss will deteriorate, which is not preferable.

Also, the rubber concentration in the transparent styrene resin is 0.01 to 0.
．． 05% by weight is preferable; if the o, oi is less than 100%, silicone oil will not be uniformly applied to the sheet, and it is necessary to increase the amount of synthetic silicon dioxide to 210t'.
The sheet surface deteriorates due to the increase of aggregates, and 0.05 weight f'
A If it exceeds 7c, the transparency will decrease, so it is not preferable or not.

Next, it is preferable that the silicon dioxide of the present invention is produced by reacting sodium silica with an acid.

The average particle diameter of the silicon is 1 to 5 μm in the form of secondary aggregates in which secondary particles are three-dimensionally bonded through siloxane bonds.
m is preferred. If it is less than 1 μm, poor dispersion will occur in the sheet due to re-agglomeration, or fish eyes will be formed, resulting in poor sheet surface appearance, and if it exceeds 5 μm, the sheet surface appearance will be impaired and fC will be impaired due to the large amount of coarse particles contained. ,
This is undesirable because it produces a sheet breaking sound during stretching.

Further, the proportion of M in the resin is preferably 30 to 600 pμm, and if it is less than 3 opμm, the protrusion ratio to the sheet surface is small, which weakens the sheet blocking property, and the peelability of molded products obtained from the sheet when stacked is poor. Moreover, it becomes necessary to increase the rubber content, and 300 pμm
If this value is exceeded, chances of reaggregation of silicon dioxide increase, resulting in deterioration of the transparency and appearance of the sheet, generation of sheet breakage noise during stretching, and the characteristics of use in combination with the rubber component are weakened.

Further, the resin composition of the present invention may contain additives such as a lubricant, a plasticizer, and a coloring agent, if necessary.

The resin composition for the stretched sheet of the present invention may be prepared by tri-blending the diene rubber-containing M transparent styrenic resin and synthetic silicon dioxide using a Henschel mixer, a blender, etc. Any method may be used, such as making a master pellet of the resin composition, or mixing it with a transparent styrene resin containing diene rubber as a resin binder.

Furthermore, the styrene resin stretched sheet of the present invention has an Ostwald viscoelasticity (20°C) of 100 to 200,000 on its surface.
The structural formula of centistokes is 8% Silicon oil alone or an emulsion containing an emulsifier can be used alone or as an anti-grooving agent or antistatic agent, and the range is 10-150σv/y12.

(Example) The present invention will be described in detail below with reference to Examples. The average particle diameter was measured using the Coulter counter method.
This is the volume average particle diameter.

Transparent styrene resin and graft mold mouth 9mm modified styrene resin (rubber concentration 6% by weight) as shown in Table 1.
), and further mixed with synthetic silicon dioxide (Fuji Davison ■, "trade name Thyroid") in the amount and average particle size shown in Table 1 into the mixed resin to form a resin composition. It was extruded into a sheet form from an extruder and stretched 2.5 times vertically and horizontally to obtain a 150 μm 2III stretched sheet 14-.

Next, apply 50I of silicone oil to the surface of the stretched sheet.
It was applied so that the ratio was n9/nL2.

The results of measuring the properties were good as shown in Table 1.

Comparative Example The same procedure as in Example was carried out, except that the rubber content and average particle size of the styrene graft rubber, as well as the amount of synthetic silicon dioxide and the average particle size were shown in the $2 table. % result of second
Shown in the table. As shown in the characteristics evaluation column, it is inferior.

The characteristics evaluation methods shown in Tables 1 and 2 are as follows.

1. Peelability of sheet, according to ASTM-D-1894 ◎ (Good): 0.35 or less ○ (Good): 0.35N to 0.40 Δ (Slightly Good'): Over 0.40 to 0.45 × (defective): over 0.45, 2. Transparency, No. made by Nippon Juishiki)! - The degree of haze was measured using a 2D turbidimeter based on a sheet thickness of 150 μm.

◎ (Good): O, S or less O (Good): Over 0.5 ~ 1.0 ~ △ (Slightly Good'): Over 1.0 ~ 1.5% × (Poor): 1.5% Super 3: The number of protrusions on the sheet surface: The number of protrusions of 0.1 to 1 μm in length of 20 cIIL was measured using a two-dimensional surface roughness meter manufactured by Tokyo Seimitsu.

◎ (Good'): 151 or more O (Good): 101 to 150 △ (Slightly Good): 51 to 100 × (Poor): 50 or less 4, Number of coarse particles, 25cIIL included in square sheet The number of fish eyes with a size of φ10 or more was visually measured.

◎ (Good) 2 0-1 pieces ○ (Good) = 2-4 pieces △ (Slightly good): 5-7 pieces x (Poor) = 8 or more pieces 5, Silicone oil mark, when two sheets are stacked The area of the resulting map pattern (100 sections) was visually measured.

◎ (Good): 5% or less O (Good): More than 5 to 25 △ (Slightly good): More than 25 to 50% × (Bad): More than 50% (Effect of the invention) The styrene of the present invention Stretched resin sheets have even minute irregularities on the surface of the sheet, so silicone oil can be applied evenly, and foreign matter contamination due to thermal deterioration of the rubber can be minimized to prevent appearance and sheet breakage. It has the characteristics of weakening the blocking property of molded products and having good peelability when stacking molded products.

Claims (1)

[Claims] Synthesis of a transparent styrenic resin containing 0.01 to 0.05% by weight of styrene grafted diene rubber with an average particle diameter of 1 to 5 μm and an average particle diameter of 1 to 5 μm containing 30 to 300 pμm in the resin A stretched styrenic resin sheet characterized by being formed by biaxially stretching a resin composition made of silicon dioxide.