JPH0641171B2 - Dimensional stability method for stretched polymer materials - Google Patents

Description

TECHNICAL FIELD The present invention relates to a heat treatment for the purpose of greatly enhancing the dimensional stability of a stretched polymer plate.

Conventional technology Polymer materials have advantages such as light weight, no rust, poor electrical and thermal conductors, resistance to acids and alkalis, and easy molding, but on the other hand, tensile strength, elastic modulus (Young's modulus) and hardness・ The heat resistance is inferior to that of metal. In particular, it is said that if strength and elastic modulus are improved, the use in various vehicles including automobiles, aircraft, industrial machines, electronics, information, chemical industry, etc. will be greatly increased.

Generally, when a crystalline polymer material is stretched in two directions near its melting point, the strength of the stretched material is strengthened in any direction, as shown in Japanese Patent Application No. 62-41419.

However, in these stretched materials, since the molecular chains are stretched by deformation at a temperature just below the melting point, the stretched molecular chains contract when the temperature rises. Therefore, when used at high temperature, a large dimensional change occurs, and the range of use is limited.

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention The present invention aims to solve these drawbacks of the prior art, and provides a heat treatment method for increasing the dimensional stability of a stretched polymer plate at high temperature. Is what you are trying to do.

Means for Solving the Problem A feature of the present invention is that a polymer material made of polyethylene or polyamide biaxially rolled between rolls is heated at 50 to 150 ° C.
In the temperature range of 30 ~ 240 minutes for a short time heat treatment.

Hereinafter, the present invention will be described in detail.

The starting material in the present invention is a polymer plate stretched in two directions near the melting point. Examples of materials that can be effectively subjected to heat treatment include reinforced and stretchable thermoplastic polymer materials such as polypropylene, polyamide and polyethylene.

The plate is heat treated in the temperature pattern shown in FIG. As the heating device, an appropriate thing such as a hot air stove or an infrared heater may be used, and a plate heater sandwiched by heating plates from above and below may be used. After being heated to a predetermined temperature, the temperature is maintained at a constant temperature thereafter until the dimensional change does not proceed any further.

The time depends on the type of resin, the degree of processing, and the temperature, so it can be confirmed in advance by preliminary experiments or the dimensions can be measured successively during heat treatment. Also, since the dimensional stability does not change even if the heating time becomes longer than necessary,
If the measurement is difficult, the heating time may be set longer.

Then, when the dimensional change converges or when more time elapses, it is taken out of the heating furnace and air-cooled. Due to this heat treatment, the stretched biaxial plate hardly undergoes dimensional change at least below the heat treated temperature.

That is, if a heat treatment suitable for the material is performed, a stretched polymer material having high dimensional stability can be obtained even when used at high temperature.

Examples Examples will be described below.

Example 1 Table 1 shows rolling conditions for a polypropylene (hereinafter abbreviated as PP) biaxially rolled plate. As a rolling procedure, first, rolling was carried out in one direction under the conditions shown in Table 1, and rolling was carried out in the second direction while changing the 90 ° direction. This rolled plate is a strength isotropic plate having a tensile strength of 10 kgf / mm ² in any direction.

Then, as a preliminary experiment, when the rolled material was loaded into a warm air heating furnace where the temperature was kept at 80 ° C and the dimensional change due to heating was observed in detail, the dimensional change converged at this temperature. It took 60 minutes.

Based on the above results, the above-mentioned PP heating plate was heat-treated in a heat treatment pattern (heating for 60 minutes) as shown in FIG. That is, the rolled material was loaded into a hot air heating furnace whose temperature was maintained at 80 ° C., heated for 60 minutes, taken out of the furnace, and air-cooled to room temperature. The above heat-treated material is referred to as Example 1.

For comparison, only the heating time at the same pattern and temperature is 20
Minutes, heat treated for 3 hours and 6 hours, and those not heat treated at all are shown.

FIG. 3 shows a comparison of the dimensional change rate in the atmosphere of 80 ° C. between Example 1 and the example for comparison. As a comparison method,
Cut a 50 mm x 50 mm test piece from each material and
After storing in an atmosphere of ℃ for 24 hours, L direction (second rolling direction) and C direction (direction forming 90 ° with the second rolling direction)
Was measured and examined by the rate of dimensional change (Δε = dimensional change / dimension before heating, the sign of Δε corresponds to the elongation and contraction of the material).

If the processing time was as short as 20 minutes, L direction: 2.1%, C
Direction: -2.3% dimensional change occurred, and in the untreated material, L direction: 4.8%, C direction: -5.2%. However, in Example 1, L direction: 0.4%, C direction:-
Only the dimensional change of 0.3% occurred, and it can be said that the dimensional stability was significantly improved by the heat treatment according to the present invention.

In addition, the dimensional changes of the ones having a longer heat treatment time of 3 hours and 6 hours were the same as in Example 1, L direction: 0.4%, C direction: -0.
It is 3%, and the effect does not change even if the processing time is unnecessarily lengthened.

Example 2 A PP rolled material similar to that of Example 1 was loaded into a hot air heating furnace whose temperature was maintained at 110 ° C., and when the successive changes in shrinkage were observed in detail, the dimensional changes converged at this temperature. It took 110 minutes.

Based on the above results, the above PP heating plate was heat-treated in a heat treatment pattern (heating for 110 minutes) as shown in FIG. That is, the rolled material was carried into a warm air heating furnace whose temperature was maintained at 110 ° C., heated for 110 minutes, taken out of the furnace, and air-cooled to room temperature. The above heat-treated material is referred to as Example 2.

For comparison, the heating time is 30 at the same pattern and temperature.
Minutes, heat treated for 3 hours and 6 hours, and those not heat treated at all are shown.

FIG. 5 shows a comparison of the dimensional change rate in the 110 ° C. atmosphere between Example 2 and the comparative example. The comparison method is the same as that in Example 1 except that the atmospheric temperature is set to 110 ° C.

If the processing time was as short as 30 minutes, L direction: -3.5%, C
Direction: -3.1% dimensional change occurred, and in the untreated material, L direction: -9.5%, C direction: -5.2%. However, in Example 2, slightly in the L direction: -0.4%, C
Direction: Only -0.3% dimensional change occurred, and it can be said that the dimensional stability was significantly improved in this case as well.

In addition, the dimensional changes of the ones having a longer heat treatment time of 3 hours and 6 hours are the same as in Example 2, L direction: -0.4%, C direction:-
It is 0.3%, and the effect does not change even if the processing time is unnecessarily lengthened.

Example 3 Table 2 shows rolling conditions of a polyamide (hereinafter abbreviated as PA) biaxially rolled plate. As the rolling procedure, first, rolling was carried out in one direction under the conditions shown in Table 2, and rolling was carried out in the second direction while changing the 90 ° direction.

As in Example 1, the above PA rolled material was loaded into a hot air heating furnace whose temperature was kept at 130 ° C., and when the successive changes in shrinkage were observed in detail, the dimensional changes converged at this temperature. It took 40 minutes.

Based on the above results, the above-mentioned PA heating plate was heat-treated in a heat treatment pattern (heating for 40 minutes) as shown in FIG. That is, the rolled material was carried into a warm air heating furnace whose temperature was kept at 130 ° C., heated for 40 minutes, taken out of the furnace, and air-cooled to room temperature. The above heat-treated material is referred to as Example 3.

For comparison, only 10 minutes of heating at the same pattern and temperature
Minutes, heat treated for 3 hours and 6 hours, and those not heat treated at all are shown.

FIG. 7 shows a comparison of the dimensional change rate in Example 3 and the comparative example in a 130 ° C. atmosphere. The comparison method is the same as that of the example 1 except that the atmospheric temperature is set to 130 ° C.

If the processing time was as short as 10 minutes, L direction: -1.8%, C
Direction: -2.1% dimensional change occurred, and in the untreated material, L direction: -4.5%, C direction: -3.8%. However, in Example 3, slightly in the L direction: -0.2%, C
Direction: Only -0.3% dimensional change occurred, and it can be said that the dimensional stability was significantly improved in this case as well.

In addition, the dimensional changes of the ones having a longer heat treatment time of 3 hours and 6 hours are the same as in Example 3, L direction: -0.2%, C direction:-
It is 0.3%, and the effect is the same even if the treatment time is unnecessarily lengthened.

EFFECTS OF THE INVENTION As described above, the present invention is a heat treatment method for a stretched polymer material, and has the effect of greatly improving the dimensional stability at high temperatures.

[Brief description of drawings]

FIG. 1 is a diagram showing a heat treatment pattern of the present invention. FIG. 2 is a diagram showing a heating pattern when a PP biaxially rolled plate is used at 80 ° C. Fig. 3 shows a PP biaxially rolled sheet with 24
It is a figure which compared the dimensional change of the heat processing material and the non-processing material after storing for a time. FIG. 4 is a diagram showing a heating pattern when a PP biaxially rolled plate is used at 110 ° C. Fig. 5 shows a PP biaxially rolled plate in an atmosphere of 110 ° C.
It is a figure comparing the dimensional change of a heat treatment material and a non-treatment material after storing for 4 hours. FIG. 6 is a diagram showing a heating pattern when a PA biaxially rolled plate is used at 130 ° C. Fig. 7 shows the results for a PA biaxially rolled plate in an atmosphere of 130 ° C.
It is a figure comparing the dimensional change of a heat treatment material and a non-treatment material after storing for 4 hours.

Continuation of the front page (72) Inventor Toshio Kikuma 1-1-1 Emitsu, Hachimanto-ku, Kitakyushu, Fukuoka Prefecture Inside the 3rd Technical Research Laboratories, Nippon Steel Co., Ltd. (56) Reference JP 54-148068 (JP, A) ) JP-A-60-99648 (JP, A) JP-B-49-14539 (JP, B2)

Claims (1)

[Claims] 1. A polymer material made of polyethylene or polyamide which is biaxially rolled and stretched between rolls at 50 ° C. to 150 ° C.
A dimensional stabilization method for a polymer material, which comprises heat-treating at a temperature range of ℃ or less for 30 to 240 minutes.