JP3192722B2 - Resin composition for vacuum forming - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a resin composition having excellent low-temperature impact resistance and rigidity, low drawdown during vacuum forming and good vacuum moldability. By vacuum forming a sheet formed from the resin composition, it can be used in many industrial fields. Some examples are suitably used for components requiring high rigidity and low-temperature impact resistance, such as refrigerator door liners and inner boxes. Also, there may be mentioned molded products of automobile parts such as door liners and console boxes which require higher rigidity.

[0002]

2. Description of the Related Art As a method for imparting rigidity, it is known to add a nucleating agent to crystalline polypropylene or blend an inorganic filler. Regarding the nucleating agent, there is a problem in the effectiveness of the rigidity improving effect with respect to the ethylene-propylene copolymer among the crystalline polypropylenes. Although the rigidity is increased by blending the inorganic filler, impact resistance is reduced. Therefore, it is considered that high-density polyethylene is blended as the third component to cover the reduction in impact resistance.

[0003]

A resin composition satisfying both high rigidity and impact resistance and having further excellent vacuum moldability is a known composition of crystalline polypropylene, high-density polyethylene and an inorganic filler. You can't get it. That is,
If a large amount of high-density polyethylene is blended in order to improve vacuum formability, the rigidity will be significantly reduced. Therefore, when a large amount of the inorganic filler is blended, the impact resistance is reduced. As described above, the conventional resin composition has a drawback that it cannot simultaneously satisfy the three characteristics of high rigidity, good impact resistance, and excellent vacuum moldability.

[0004]

Means for Solving the Problems In order to simultaneously satisfy these three properties, the present inventors have found a composition which does not cause a decrease in vacuum moldability even if the amount of high-density polyethylene is reduced. I thought I had to. By blending two specific high-density polyethylenes, a resin composition having high rigidity, good impact resistance, and excellent vacuum moldability was found, and the present invention was completed.

That is, the present invention relates to (A) 40 to 60% by weight of crystalline polypropylene and (B) high density polyethylene having a melt flow rate of 0.1 to 1.0 g / 10 min (hereinafter referred to as high density polyethylene (I)). ) 10-30% by weight,
(C) a melt flow rate of 0.02 to 0.08 g / 10
Min high density polyethylene (hereinafter high density polyethylene (I
(I) 5-15% by weight, (D) inorganic filler 20
４０40% by weight of the resin composition.

The crystalline polypropylene may be a homopolymer or a block copolymer or a random copolymer with an olefin such as ethylene. This melt flow rate (hereinafter, referred to as MFR) is 0.1 to
3.0 g / 10 min (230 ° C.), preferably 0.3-2.
0 g / 10 min. High density polyethylene (I) is MFR
Is 0.1 to 1.0 g / 10 min (190 ° C.), preferably 0.2 to 0.5 g / 10 min. The weight average molecular weight of this polyethylene (I) is from 80,000 to 130,000, preferably from 90,000 to 110,000. If the MFR is less than 0.1 g / 10 minutes, the moldability will be poor, and if it exceeds 1.0 g / 10 minutes, the impact value of the molded article will decrease. As the inorganic filler, in addition to metal salts such as calcium carbonate and magnesium carbonate, talc, mica, clay and the like are used for the purpose of improving rigidity. The particle size is suitably 15 μm or less.

We have determined that the above composition has rigidity, impact resistance,
High density polyethylene (II) as the second component was blended in order to simultaneously satisfy three of the vacuum moldability. This high-density polyethylene (II) has an MFR of 0.02 to 0.08 g / 10 minutes (190 ° C.), preferably 0.03 to 0.06 g
/ 10 minutes (190 ° C.). Weight average molecular weight is 150,000 ~
350,000, preferably 200,000 to 300,000. This MFR
If it is less than 0.02, the MFR of the composition will be too small, and the extrudability of the sheet to be subjected to vacuum forming will be poor, and the appearance of the sheet will also be poor. On the other hand, if the MFR exceeds 0.08, the drawdown resistance during vacuum forming cannot be improved, resulting in poor moldability.

The resin composition of the present invention further comprises an antioxidant used for polypropylene, polyethylene and the like,
UV absorbers, lubricants, pigments and the like can be added. In the composition ratio of the composition of the present invention, the content of the crystalline polypropylene is 40 to 60% by weight. If the amount is less than 40% by weight, the rigidity and heat resistance are reduced when the amount of the inorganic filler is fixed. If the amount is more than 60% by weight, the impact resistance, particularly the low-temperature impact value, is not preferred.

For high density polyethylene (I), 1
If it is less than 0% by weight, the impact resistance is lowered, which is not preferable.
On the other hand, if it exceeds 30% by weight, the rigidity is reduced. If the component amount of the high-density polyethylene (II) is less than 5% by weight, the melt tension of the composition cannot be increased, so that the drawdown in vacuum molding becomes large, and a thin and uniform molded article can be obtained. I can't get it. On the other hand, when it is added in an amount exceeding 15% by weight, the MFR of the composition is greatly reduced and the formability of the sheet is deteriorated. When the amount of the inorganic filler is less than 20% by weight, a material having a high rigidity value cannot be obtained. If the content exceeds 40% by weight, the impact resistance is reduced and the vacuum formability is deteriorated, which is not preferable.

[0010]

EXAMPLES Examples and comparative examples according to the present invention are shown in Table 1.
In the table, the flexural modulus was measured by the ASTM D-790 method and used as an index of rigidity. Notch impact value is ASTM D
It is an Izod impact value measured by the -256 method. Vacuum formability is as follows: A 1.0 mm thick sheet is vacuum-formed at 180 ° C (sheet surface temperature) using a female mold with a bottom surface of 10 × 10 cm and a depth of 5 cm. It was visually determined. The sheet formability is 600mmT-
The appearance and the degree of thickness deviation of the sheet taken from the die were examined and judged.

Example 1 As a crystalline polypropylene, an ethylene propylene block copolymer having an MFR of 0.7 g / 10 min was used. High density polyethylene (I) has a MFR of 0.2 g / 10 min and a density of 0.9
Use 55 g / cm ³ of resin, high density polyethylene (I
I) has an MFR of 0.04 g / 10 min and a density of 0.940 g
/ Cm ³ resin was used. The inorganic filler has a central particle size of 1 to
Using a commercially available talc of 5 μm, the mixture was granulated at a resin temperature of 220 ° C. by a 30 mmφ twin screw extruder at a compounding ratio as shown in Example 1 of Table 1.

[0012] The granulated product was extruded into a 1.0 mm
The sheet was formed into a thick sheet, and the sheet was examined for formability. or,
The sheet was formed by a vacuum forming machine, and the vacuum formability was examined. On the other hand, the flexural modulus and the notched impact value were measured by preparing test pieces with an injection molding machine. As a result, the flexural modulus at 23 ° C. was 28,000 kgf / c.
m ² and a notched impact value at −20 ° C.
It was 1 kgf · cm / cm ² . Regarding the formability of the sheet, a sheet with less unevenness and a good appearance was obtained.
As for the vacuum formability, a good drawn product with less uneven thickness was obtained.

Example 2 The same molding and evaluation as in Example 1 were carried out except that the amounts of the high-density polyethylenes (I) and (II) were changed in Example 1. As a result, both vacuum moldability and sheet moldability were good.

Example 3 The same molding and evaluation were conducted as in Example 1 except that the component amounts of the high-density polyethylene (I) and (II) were changed. Was particularly good.

Example 4 In Example 1, the amounts of the components of the crystalline polypropylene, the high-density polyethylene (II) and the inorganic filler were changed. In particular, the amount of the inorganic filler was increased. As a result, the bending elastic modulus increased, but the notched impact value decreased. However, sheet formability and vacuum formability were good.

Comparative Example 1 As a result of performing molding and evaluation in the same manner as in Example 1 except that the component amount of the high-density polyethylene (II) was lower than the scope of the claims, a vacuum molded product was found to have a thin portion. And uneven wall thickness accuracy was poor.

Comparative Example 2 In Example 1, high-density polyethylene (II) was formulated and evaluated in the same manner as in Example 1 with a blending ratio larger than the claimed range. Only poor appearance was obtained. Also, the flexural modulus is low.

COMPARATIVE EXAMPLE 3 As a result of using a high-density polyethylene (II) having an MFR of 0.015 smaller than the claimed range, the sheet had poor workability due to sheet formability and had a problem in appearance. Therefore, the appearance of the vacuum formed product was also poor.

Comparative Example 4 As a result of molding evaluation using MFR of high-density polyethylene (II) of 0.1 which is larger than the claimed range, a thin-walled portion is formed in the vacuum-formed product and the uneven thickness is large. Was.

Comparative Example 5 As a result of molding and evaluation using an inorganic filler exceeding the scope of the claims in Example 1, not only the vacuum molded product was not good but also the notched impact value was low. It became.

[0021]

[Table 1]

[0022]

The resin composition according to the present invention not only has excellent vacuum moldability, but also has good rigidity and impact resistance, and can be formed into a thin molded product. It can be used for refrigerator interior parts and automobile interior parts that have been used. Considering the superior impact resistance and lower material cost of these ABS and polystyrene resins, it can be expected that applications in the fields of home appliances, industrial materials, and the like will be expanded.

Continuation of the front page (56) References JP-A-2-68015 (JP, A) JP-A-59-157136 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C08L 23 / 00-23/36 C08K 3/00-13/08

Claims (1)

(57) [Claims] (A) crystalline polypropylene 40 to 60
% By weight, (B) melt flow rate is 0.1 to 1.0 g
10 to 30% by weight of high-density polyethylene for 10 minutes, (C)
A vacuum molding resin composition comprising 5 to 15% by weight of high-density polyethylene having a melt flow rate of 0.02 to 0.08 g / 10 min and (D) 20 to 40% by weight of an inorganic filler.