JPH06240018A - Shock-absorbing sheet and thermoformed article made therefrom - Google Patents

Abstract

PURPOSE:To develop an elastomer which can be formed into a thermoformable sheet having good shock-absorbing properties. CONSTITUTION:A block polyester consisting of a polyester part (A) composed mainly of an aromatic dicarboxylic acid and a 5C or higher glycol and having a melting point of at most 100 deg.C or comprising a noncrystalline polyester and a thermoplastic polyester part (B) having a melting point of at least 150 deg.C is formed into sheet to give the objective shock-absorbing sheet. If necessary, this sheet is thermoformed to give the objective thermoformed article.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sheet having an impact absorbing ability and a thermoformed article made of the sheet. More specifically, it is a shock-absorbing sheet made of a block polyester containing an amorphous or low crystalline aromatic soft polyester as a soft component and a high melting point polyester as a hard component, and a thermoformed product thereof.

[0002]

2. Description of the Related Art Regarding shock absorption, it is well known that various products using alpha gel have been recently manufactured. For example, there is one that uses a shock absorbing gel for the sole of the shoe to absorb the shock to the foot when jogging or the like.

However, this alpha gel is inferior in mechanical properties such as tensile strength and tear strength and cannot be used alone. Although there are rubber-based impact absorbing materials such as butyl rubber, it is difficult to form them into a thin sheet, and it is impossible to further thermoform the sheet.

On the other hand, as the impact absorbing polyester, the present inventors have already proposed low resilience polyester in Japanese Examined Patent Publication Sho 60.
-35365, etc. However, in this application, no consideration was given to sheet formation and thermoforming.

[0005]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a molded article in which a sheet having a shock-absorbing resin is formed into a sheet and, if necessary, the sheet is provided with irregularities by thermoforming. The reason for this is that shock absorption can be more effectively utilized by using a sheet or a thermoformed sheet.

[0006]

Therefore, as a result of repeated studies to solve this problem, the present inventors have made a material that can be formed into a sheet with a shock-absorbing resin and that can be thermoformed into a sheet. As a result of the search, the inventors have found that the polyester block copolymer is suitable for this purpose and arrived at the present invention.

That is, according to the present invention, a thermoplastic resin having an aromatic dicarboxylic acid and a glycol having a carbon number of 5 or more as a main constituent and a melting point of 100 ° C. or more or an amorphous polyester part (A) and a melting point of 150 ° C. or more is used. It is a shock-absorbing sheet obtained by molding a block polyester composed of a polyester portion (B) into a sheet shape, and is a thermoformed product obtained by further thermoforming this shock-absorbing sheet.

The aromatic dicarboxylic acid constituting the polyester portion (A) is a dicarboxylic acid in which a carboxyl group is directly bonded to an aromatic ring such as a benzene ring or a naphthalene ring, and examples thereof include isophthalic acid, terephthalic acid and phthalic acid. , Naphthalene dicarboxylic acids and the like. In particular, since the polyester portion (A) needs to have a low melting point or an amorphous property, a dicarboxylic acid having a low linearity when used as a polyester such as isophthalic acid and phthalic acid is preferably used.

Examples of glycols having 5 or more carbon atoms include hexamethylene glycol, decamethylene glycol, 3-methylpentamethylene glycol and 2-methyloctamethylene glycol, and those having 12 or less carbon atoms are common. is there.

The polyester part (A) is a polyester composed of the above-mentioned aromatic dicarboxylic acid and glycol. In addition to the above, for example, aliphatic or alicyclic dicarboxylic acids, aromatic or alicyclic dicarboxylic acids. A diol such as may be copolymerized.

The polyester composed of the component constituting the polyester part (A) must have a melting point of less than 100 ° C. or be amorphous. Preferably, the melting point is less than 50 ° C or amorphous. This is because when the melting point is a high melting point such as 100 ° C. or higher, the impact absorbency becomes poor. The glass transition temperature of the polyester is preferably changed depending on the temperature at which it is intended to be used as a shock absorbing material. For example, when it is desired to exhibit shock absorbing properties at room temperature, it is -50 to 0 ° C.
It is good to say

On the other hand, the polyester having a melting point of 150 ° C. or higher which constitutes the polyester portion (B) is generally terephthalic acid, 2,6-naphthalenedicarboxylic acid, 4,
A polyester mainly composed of a highly linear aromatic dicarboxylic acid such as 4'-diphenyldicarboxylic acid and a glycol having 2 to 4 carbon atoms or cyclohexanedimethanol is used. Of these, polybutylene terephthalate is most often used. The other copolymerization component is not particularly limited as long as it can be generally used as a copolymerization component of polyester.
At this time, the melting point may be 150 ° C. or higher.

The ratio of the polyester part (A) to the polyester part (B) is usually 50/50 to 80/20.
(Weight ratio) is used.

The block polyester of the present invention is a block copolymer comprising a polyester portion (A) and a polyester portion (B), and this block polyester is produced, for example, as follows. A high molecular weight polyester corresponding to the polyester portion (A) and a high molecular weight polyester corresponding to the polyester portion (B) are melt-reacted to have a melting point of 2 or more than the melting point of the high molecular weight polyester corresponding to the polyester portion (B). Manufactured to be -40 ° C lower. However, it goes without saying that it may be manufactured by a manufacturing method other than this. The block polyester usually has an intrinsic viscosity of 0.6 or more, preferably 1.0 or more, measured at 35 ° C. in orthochlorophenol.

In the present invention, the block polyester needs to be formed into a sheet. This sheet has a thickness of 10
~ 5000 μm, especially 50-2000 μm
Often used. This sheet can be formed into a sheet by the same method as that for forming a normal thermoplastic polyester sheet, but in some cases, the sheet has high tackiness, so that release paper or the like should be inserted or fine powder should be attached. May be required. In such a case as well, a commonly used method can be applied. For example, a method in which a die such as a T die or an I die is attached to the tip of a melt extruder, the block polyester is melt extruded, extruded into a sheet, and cooled with a cooling drum is common.

The sheet thus obtained is generally used as it is without being stretched, but it can be stretched and used when a thin sheet is required or when mechanical strength is desired.

The present invention includes an embodiment in which the sheet is thermoformed and used. The thermoforming refers to heating a sheet to perform processing such as vacuum forming, pressure forming, and press forming.

For this molding, it is important to set the temperature of the sheet to a temperature 5 to 40 ° C. lower than the melting point of the block polyester and perform the molding process. This is because when the sheet temperature is lower than this, the so-called springback phenomenon cannot be performed and the molding cannot be performed as it is, which is not preferable. Other conditions need to be appropriately determined, but may be performed in the same manner as in ordinary molding.

The thus-obtained sheet of the present invention and the thermoformed article thereof contain stabilizers, pigments, fillers, other resins, plasticizers and other various additives in addition to the block polyester described above. But it doesn't matter.

[0020]

EFFECTS OF THE INVENTION The block polyester of the present invention has a vibration absorbing property by itself, but the effect of the vibration absorbing property varies depending on the shape. In particular, since the block polyester used in the present invention is harder than the conventionally used alpha gel, it often does not always work well even if it is intended to have vibration absorption in bulk. This is considered to be because, when the object vibrates, the vibration is transmitted to the support as it is in a shape having high rigidity.

On the other hand, in the case of a sheet or its molded product, a force is applied in the bending direction of the sheet, and therefore, when the object vibrates, the sheet or its molded product is deformed, which is a characteristic of block polyester. It is thought that the vibration absorption is utilized. That is, according to the present invention, the vibration absorption characteristic of the block polyester used in the present invention can be effectively utilized for the first time.

The sheet of the present invention or a molded article thereof includes
For example, it is used as a shock absorbing material for sports shoes and the like, as a vibration absorbing material for machinery and the like, and as an absorbing material for various vibrations and shocks.

[0023]

The present invention will be described in detail with reference to the following examples. In the present invention, "part" means "part by weight".

[0024]

Example 1 After transesterification of 175 parts of dimethyl isophthalate, 23 parts of dimethyl sebacate and 140 parts of hexamethylene glycol with a dibutyltin diacetate catalyst,
Polycondensation was carried out under reduced pressure to obtain a starch syrup-like polyester having an intrinsic viscosity of 1.06 at room temperature. The amount of this polyester calculated from the amount of distillate was 252 g (polyester part A
Equivalent to).

A chip of polybutylene terephthalate (corresponding to polyester part B, melting point: 223 ° C.) having an intrinsic viscosity of 0.98, which was separately obtained by polycondensation in the same manner, was dried and 107 parts was added to 240 ° C. When the reaction was carried out for another 40 minutes, the inside became transparent. After reacting for another 5 minutes, 0.1 part of phenylphosphonic acid was added to stop the reaction. This block polyester was taken out and made into chips to be used as a raw material for sheet production. The melting point of this chip was 190 ° C. and the intrinsic viscosity was 1.03 (polyester A / polyester B = 70/30).

The obtained chips were extruded from a 40 mm extruder equipped with a T-die at 230 ° C., immediately cooled by a cooling drum having water on the surface thereof, and then a release paper was sandwiched and wound up. The thickness of this sheet was set to 100, 300, and 700 μm by changing the rotation speed of the cooling drum.

This sheet has a width of 2 mm, a depth of 2 mm and a length of 5
Sheets were formed using a die in which ten 0 mm grooves were engraved at intervals of 2 mm. This sheet was fitted in a frame, brought into contact with a mold when it became transparent by heating from above and below, and a vacuum was applied to bring it into close contact with the mold. At this time, the mold temperature was 40 ° C. The temperature of the sheet was 176 ° C. as a result of measurement with a non-contact thermometer. The obtained molded product was molded according to the mold. However, the one with a thickness of 100 μm was deformed and could not return even if a little force was applied.

The obtained molded product was placed on an iron plate with the convex surface facing upward, and the weight (length) was 1 cm in diameter from the height of 10 cm on the lower surface.
Table 1 shows the results of measuring the repulsion height by dropping a cylindrical object (made of iron) having a different shape so that the circular surface faces downward. The low repulsion height is considered to have absorbed the impact force.

[0029]

[Table 1]

[0030]

Examples 2-3, Comparative Example 1 In Example 1, as the polyester constituting the polyester part A, polyesters obtained from the raw materials shown in Table 2 were used, and the ratio of the polyester part A to the polyester part B was calculated. The repulsion height (weight 5
0 g) was measured. The results are shown in Table 2.

For comparison, an example in which an aliphatic polyester is used as polyester A is shown as a comparative example.

The reaction between the polyester constituting the polyester A and the polyester constituting the polyester B is a reaction in which the content becomes transparent and is further reacted for 3 minutes, and then the reaction is stopped by adding phenylphosphonic acid. Is.

[0033]

[Table 2]

Claims (2)

[Claims] 1. A polyester portion (A) having an aromatic dicarboxylic acid and a glycol having 5 or more carbon atoms as a main constituent and having a melting point of 100 ° C. or lower or an amorphous component, and a melting point of 150 ° C.
An impact absorbing sheet obtained by molding a block polyester comprising the above thermoplastic polyester portion (B) into a sheet shape. 2. A thermoformed product obtained by molding the block polyester into a sheet and then thermoforming it.