KR100947707B1 - Composition for heat-shrink tubing with high strength and resistance against heat and oil and heat-shrink tubing using the same - Google Patents

Abstract

The present invention relates to a resin composition for high strength, high heat resistance and high oil resistance heat shrink tube. In the present invention, a resin composition for a heat shrinkable tube is added with a lead-free hydrolysis stabilizer, a halogen-based flame retardant, and a flame retardant aid to a polymer blend base resin composed of ethylene-vinyl acetate grafted thermoplastic polyester elastomer and maleic anhydride. And a heat shrink tube obtained using the same.

Heat Shrink Tubing, High Strength, Heat Resistant, Oil Resistant, Polyester Elastomer, Lead Free Hydrolysis Stabilizer

Description

Composition for heat-shrink tubing with high strength and resistance against heat and oil and heat-shrink tubing using the same}

The present invention relates to a composition for manufacturing a heat shrinkable tube having high heat resistance, high strength and excellent resistance to oil. More specifically, the present invention relates to a hydrolysis without a lead component using a polymer blend based on a thermoplastic polyester elastomer as a base resin. A composition for high strength, high heat resistance and high oil resistance heat shrinkable tubing using a stabilizer.

A heat shrink tube is a tube having a property of shrinking in diameter or length when cured after heating. The heat shrink tube is used for packaging by tightly covering a connection part such as a coated wire or a pipe or being fitted to the outer circumferential surface of a bottle or a battery. In a widely used method of manufacturing a heat shrink tube, the thermoplastic resin is first extruded, and then the thermoplastic resin is crosslinked using a method such as electron beam irradiation. The crosslinked resin is then heated to a temperature above its crystal melting temperature to expand and then cooled to prepare the final product.

Resin for the heat shrink tube of the prior art was mainly used polyethylene (PE), chlorinated polyethylene (CPE), ethylene-vinyl acetate copolymer resin and lead-based stabilizers containing a lot of lead components were used. However, the conventional heat shrink tube has a problem in that the tensile strength is low at room temperature and the continuous use temperature is less than 125 ° C. in terms of physical properties of the polymer resin used. The problem of low continuous use temperature is particularly pronounced in chlorinated polyethylene, which is inconvenient to use in the conventional heat-cooled manufacturing method described above, and also poor in processability due to properties such as tensile strength. Polyethylene resins also suffer from low oil resistance when exposed to oil.

In addition, the lead component, including the hydrolysis stabilizer used in the conventional heat shrink tube, is increasingly required to be replaced with other components as environmental regulations become increasingly strict. However, when lead-free stabilizers are used, there is a problem that the heat resistance is inferior to that of the conventional heat shrink tube, which does not meet the requirement of increasing the continuous use temperature of the manufacturing process as much as possible to improve the performance of the product.

Therefore, there is a need in the related art to develop a resin composition for heat shrinkable tubes having no heat content and improving heat resistance and mechanical properties and having oil resistance.

The technical problem of the present invention is to develop a composition having a high tensile strength and elongation at room temperature, a high temperature, and an oil exposure environment as a polymer resin composition for a heat shrinkable tube containing no lead component and having excellent flame retardancy.

In order to achieve the above object, the resin composition for heat shrinkable tube of the present invention is 5 to 20 parts by weight of lead-free hydrolysis stabilizer, 10 to 50 parts by weight of halogen-based flame retardant based on 100 parts by weight of the polyester-based base resin composed of a polymer blend And 10 to 50 parts by weight of antimony trioxide flame retardant aid.

The polyester base resin of the present invention is a polymer blend composed of 70 to 90 wt% of thermoplastic polyester elastomer (TPEE) and 10 to 30 wt% of ethylene-vinyl acetate copolymer resin grafted with maleic anhydride.

The resin composition for a heat shrinkable tube of the present invention may further include an antioxidant, a lubricant and a crosslinking aid in addition to the above components.

The present invention also provides a heat shrink tube produced using such a composition for heat shrink tubes.

The resin composition for heat shrinkable tubes of the present invention is superior in mechanical properties such as tensile strength and elongation rate and excellent in expansion workability than the resin composition of the prior art. It also has excellent durability and environmental friendliness because it has excellent resistance to heat and oil without using lead-based stabilizers. The resin composition for a heat shrinkable tube of the present invention is suitable as a material for dissipation of a heat shrinkable tube because the continuous use temperature is higher than that of the prior art, and has an advantageous feature in the manufacturing process than the prior art.

The high strength, high heat resistant, oil resistant resin composition for heat shrinkable tube of the present invention comprises a polyester polymer blend, a lead-free hydrolysis stabilizer, a halogen flame retardant and a flame retardant aid.

The polymer blend, which is referred to as a polyester base resin in the present invention, is 70 to 90 wt% of thermoplastic polyester elastomer (TPEE) and 10 to 30 wt% of ethylene-vinyl acetate copolymer resin grafted with maleic anhydride. Is made of.

Thermoplastic polyester elastomers are polymer materials that combine the strength of plastics, the flexibility of rubber and the processability of thermoplastics. Polyester resin is an environmentally friendly material that is harmless to the human body widely used in household goods such as food containers, and does not generate toxic gases even when incinerated.

By crosslinking the thermoplastic polyester elastomer, the physical properties of the polymer, in particular, the mechanical properties can be controlled. In the widely used method of producing a heat shrinkable tube, a resin composition for heat shrinkable tube is irradiated with an electron beam to form a crosslink. The crosslinked polymer resin has high mechanical strength such as tensile strength.

The present invention provides a resin composition for a heat shrinkable tube based on a thermoplastic polyester elastomer having such excellent mechanical properties and processability. In the present invention, ethylene-vinyl acetate resin grafted with maleic anhydride is mixed to increase the crosslinking rate when forming crosslinks in the polyester elastomer so as to obtain a high strength heat shrinkable tube resin composition. To produce a polymer blend. This polymer blend becomes the basic resin used for the resin composition of this invention.

The polyester base resin is a polymer blend of 70 to 90 wt% of thermoplastic polyester elastomer and 10 to 30 wt% of ethylene-vinyl acetate (EVA) resin incorporating maleic anhydride. . When the content of the EVA resin grafted maleic anhydride in the polyester base resin of the present invention is less than 10% by weight, the crosslinking formation rate is lowered, resulting in a decrease in the mechanical strength of the final resin composition, but exceeds the content of the EVA resin by 30% by weight. Even if it raises more, crosslinking formation rate does not become high and there also exists a problem that oil resistance becomes low.

In the present invention, 5 to 20 parts by weight of a lead-free hydrolysis stabilizer based on 100 parts by weight of the base resin in order to prevent the polyester base resin from absorbing water and hydrolysis. If the content of the lead-free stabilizer is less than 5 parts by weight, it is not preferable because the physical property is not inhibited due to the inhibition of hydrolysis, and if the content of the lead-free stabilizer exceeds 20 parts by weight, the physical properties are degraded by the hydrolysis stabilizer. As shown in the following example data, the resin composition for a heat shrinkable tube of the present invention has an advantage of excellent stability in high temperature conditions and excellent mechanical properties without the use of a lead-based stabilizer.

The resin composition of the present invention uses a halogen-based flame retardant and a flame retardant aid for flame retardancy. Halogen-based flame retardants may be widely used chlorine-based or bromine-based flame retardant, ethane-1,2-bis (pentabromophenyl) is suitable as a specific example. In the present invention, the halogen-based flame retardant is used 10 to 50 parts by weight based on 100 parts by weight of the polyester-based base resin. Outside the range of use, the flame retardant effect is insignificant (less than 10 parts by weight), or a decrease in physical properties of the resin composition (greater than 50 parts by weight) without increasing the flame retardant effect.

Antimony trioxide (Sb ₂ O ₃ ) is suitable as a flame retardant adjuvant paired with a halogen-based flame retardant. Antimony trioxide helps to form a solid film during combustion to improve the flame retardancy (char) well formed, and to promote high solubility to ensure high flame retardancy. In the present invention, 10 to 50 parts by weight of antimony trioxide is used based on 100 parts by weight of the polyester base resin. If the content of the antimony trioxide is less than the lower limit of the numerical limit, flame retardancy is lowered. If the antimony trioxide content exceeds the upper limit of the numerical limit, mechanical properties such as room temperature elongation are lowered, which is not preferable.

The composition for producing a flame-retardant heat-shrink tube according to the present invention may include any one material selected from an antioxidant, a crosslinking aid, and a lubricant, or two or more materials. Even when crosslinked polyester elastomer is used, the polymer may undergo oxidative degradation by oxygen in the air at the time of manufacture of the heat shrink tube or under the high temperature conditions to be used, which leads to deterioration of physical properties such as tensile strength. . Antioxidants protect these properties by preventing these air oxidations at high temperatures. As the antioxidant of the present invention, it is preferable to use a single substance selected from a group of thioester-based and phenolic substances or a mixture of two or more selected from them, and Irganox 1010 is suitable as a specific example. In the present invention, the antioxidant is included in an amount of 0.5 to 10 parts by weight based on 100 parts by weight of the base resin.

It is preferable to use a trimethacrylic acid substance as a crosslinking adjuvant of this invention. In the present invention, the crosslinking aid is included in an amount of 1 to 10 parts by weight based on 100 parts by weight of the polyester base resin.

In the present invention, it is possible to maintain the physical properties in the state of the product by using a lubricant and to improve processability. The lubricant is preferably included in an amount of 0.5 to 10 parts by weight based on 100 parts by weight of the base resin. With respect to the numerical range for the additive content, if the lower limit is not reached, the purpose of the addition can not be achieved, and if the upper limit is exceeded, unlike the purpose of the addition, it may inhibit the physical properties of the overall resin composition Not desirable

In addition, the composition for producing a heat shrinkable tube according to the present invention may further include various functional additives commonly used in the resin composition within a range that does not impair the effects of the present invention. Such additives include sunscreens, heat stabilizers, lubricants, antiblocking agents, antistatic agents, waxes, coupling agents, pigments, and the like, although not illustrated as necessary, various types of materials may be selected and used for purposes of addition. Can be.

In this invention, the heat shrink tube manufactured using the said resin composition for heat shrink tubes is also provided. The resin composition of the present invention can be used to prepare heat shrink tubes in various forms according to well known heat shrink tube manufacturing methods. That is, the resin composition of the present invention is extruded to produce a pipe having a desired diameter, and the pipe is chemically treated or crosslinked with an electron beam. This crosslinked pipe is heated to a temperature above the crystal melting temperature and then expanded and heated by expansion of the pipe by the shrinkage of the resin measured in advance. In addition, the expanded pipe is cooled and cut to size to obtain various heat shrink tubes.

<Example>

The present invention will be described in more detail with reference to the following Examples. The average person skilled in the art to which the present invention pertains may change the present invention in various other forms in addition to the embodiments described in the following examples, and the following examples merely illustrate the present invention, and the scope of the technical spirit of the present invention is given below. It is not to be construed as limiting the scope of the examples.

In order to compare the physical properties of the resin composition for heat shrinkable tubes of the present invention with the prior art, the flame retardant resin compositions of Comparative Examples and Examples were prepared with the compositions shown in Table 1 below. All units in Table 1 are parts by weight, and are calculated using 100 parts by weight of the polyester base resin used in the resin composition. As a thermoplastic polyester elastomer (denoted as TPEE in Table 1 below) used as part of the base resin of the embodiment according to the present invention, a polyester-polyether block copolymer, Hytrel 4056, manufactured by DuPont, USA, was used. (See http://plastics.dupont.com/plastics/dsheets/hytrel/HYTREL4056.pdf for physical properties of the corresponding polyester elastomers).

The composition for heat shrinkable tubes of the comparative example was prepared and used in a similar manner. The comparative composition used a polymer blend of chlorinated polyethylene (hereinafter referred to as "chlorinated PE") and low density polyethylene (hereinafter referred to as LDPE). The chlorinated polyethylene used in the comparative example had a chlorination rate of 32%. ₃ PbO · PbSO ₄ · H ₂ O (tribasic lead sulfate, TLS) was used as lead-based stabilizer, OW-36K was used as lead-free stabilizer, and ethane-1,2-bis (pentabromophenyl) was used as halogen-based flame retardant. ) (Ethane-1,2-bis (pentabromophenyl), Saytex 8010 of Albemarle, USA) was used.

Example 1 Example 2 Example 3 Comparative Example 1 Comparative Example 2 Comparative Example 3 Chlorination PE ― ― ― 70 70 ― LDPE ― ― ― 30 30 ― TPEE (Hytrel 4056) 70 80 90 ― ― 100 Maleic Anhydride Introduced EVA 30 20 10 ― ― ― Lead free hydrolysis stabilizer 10 10 10 - ― ― Lead Hydrolysis Stabilizer ― ― ― 10 - ― Lead-free stabilizer - - - ― 10 ― Halogen flame retardant 30 30 30 30 30 30 Antimony trioxide 15 15 15 15 15 15 Antioxidant 3 3 3 3 3 3 Crosslinking aid 3 3 3 3 3 3

In Table 1, Comparative Examples 1 and 2 are blends in which the resin composition of the present invention and other polymer resins are used as base resins, and Comparative Example 3 uses a base resin composed of only a polyester elastomer.

Property measurement and evaluation

Each test specimen was prepared by the following method using the composition according to Examples (1 to 3) and Comparative Examples (1 to 4) having the composition set separately according to Table 1 above.

Each composition according to Table 1 was kneaded at 150 ° C. for 10 minutes using a roll mill, and then pressed at 200 ° C. for 10 minutes and irradiated with an electron beam to crosslink.

In order to evaluate the mechanical properties at room temperature, high temperature, and oil, the tensile strength and elongation were measured by the method shown below, and the results are summarized in Table 2 below.

㉠ room temperature

Dissipation heat shrink tubing should have tensile strength of at least 1.19 kg / mm ² and elongation of 250% when measured according to the US Department of Defense MIL-23053 / 16.

열 heat resistance

Dissipation heat shrinkable tube is tensile strength and elongation rate of 1.05 kg / mm ² after heat resistance test for 160 ° C ± 2 ° C and 168 hours in convection oven according to MIL-23053 / 16 standard. The elongation rate must be at least 200%.

In Table 2, if the test specimen was not cracked at a high temperature during the heat resistance measurement, the test was not possible.

유 Oil resistance

Heat-shrink tubing for the defense is MIL-23053 / according to 16 standard 24 ℃ ± 3 ℃ a fixed five days 6 species, after immersing 24 hours as measured by tensile strength and elongation The tensile strength of 1.05 kg / mm ² or more, elongation It should be at least 200%.

The oils used in the oil resistance test are hydraulic oils according to standards developed by the US Department of Defense, which are widely used in the industry, such as MIL-H-5606, MIL-T-5624, MIL-L-7808, MIL-L-23699, AA-694. And six types of MIL-A-8243.

㉣ flame retardant

It was measured according to ASTM 2671, a US material standard.

Example 1 Example 2 Example 3 Comparative Example 1 Comparative Example 2 Comparative Example 3 Room temperature Tensile Strength (kg / mm ² ) 1.958 1.728 1.652 1.423 1.213 1.432 Elongation (%) 636.9 597.1 581.2 605.5 663.9 640.2 Heat resistance Tensile Strength (kg / mm ² ) 1.840 1.495 1.452 Not measurable Not measurable Not measurable Elongation (%) 544.2 490.6 470.8 Oil resistance Tensile Strength (kg / mm ² ) 1.469 1.427 1.455 1.03 0.95 0.943 Elongation (%) 505.3 541.6 550.7 650 681 280.3 Flame retardant ASTM 2671 pass pass pass pass pass pass

As a result of measuring the physical properties as summarized in Table 2, the Example composition satisfies the standard value of all the properties, heat resistance, and oil resistance at room temperature, and was excellent in appearance and extrudability. The example composition was superior to the comparative composition of the prior art in terms of tensile strength, and comparable to the prior art in terms of elongation and flame retardancy. Particularly, the composition of Example was greatly improved in tensile strength at room temperature and excellent in processability without sacrificing elongation rate in the process.

Heat resistance properties are the most improved field compared to the prior art. Example composition of the present invention is 160 ° C ± 2 ° C / 168 hours in heat resistance test for 1.05 kg / mm ² of the tensile strength is the reference value It was significantly higher than, and elongation was very good. Under the same heat resistance test conditions, the comparative composition of the prior art was not able to measure heat resistance characteristics due to cracking during the test.

Looking at the oil resistance, it can be seen that the Example composition showed superior residual strength in terms of tensile strength. Elongation values after the oil test were still significantly above the baseline, but decreased relatively more than at room temperature. Overall, in view of the wide residual elongation variation (280.3 to 650%) of the prior art, the elongation oil resistance of the example composition can be said to be comparable with the prior art. In particular, the resin composition of Comparative Example 3 can be seen that the residual tensile strength is greatly reduced after exposure to oil does not satisfy the predetermined residual strength value of MIL-23053 / 16. To explain this cause without being bound to any particular theory, it is judged that the phenomenon occurred as a result of lowering the crosslinking formation rate by irradiation because the EVA resin grafted with maleic anhydride was not blended in the basic resin of the composition of Comparative Example 3.

Example composition of the present invention, although the components of the base resin is different from the comparative composition, exhibited flame resistance satisfying the ASTM 2671 standard, it was also confirmed that the reduction of the internal combustion characteristics did not occur.

In general, in Examples 2 and 3, the specific gravity of the polyester elastomer in the base resin was higher than that of Example 1, and the tensile strength and elongation were lower in the room temperature and the high temperature environment than in Example 1. However, in an environment exposed to oil, there was a characteristic that the decrease in elongation occurred less than the composition of Example 1.

As seen from these results, the high-strength, high heat, and high oil resistance resin composition of the present invention has better physical strength, elongation, and heat resistance than the prior art, and has excellent oil resistance, so that the composition ratio of the basic resin polymer blend, flame retardant, stabilizer and others The ratio of additives is properly adjusted as necessary to obtain a heat shrinkable tube that is suitable for the end use and has excellent physical properties.

As described above, optimal embodiments of the present invention have been disclosed. Although specific terms have been used in the specification including this embodiment, it is used only for the purpose of describing the invention in detail to those skilled in the art and used to limit the meaning or limit the scope of the invention described in the claims. It is not.

Claims (5)

100 parts by weight of a polyester base resin; 5 to 20 parts by weight of lead-free hydrolysis stabilizer; 10 to 50 parts by weight of halogen flame retardant; And It comprises 10 to 50 parts by weight of antimony trioxide; The polyester base resin is a polymer blend of 70 to 90% by weight of a thermoplastic polyester elastomer and 10 to 30% by weight of an ethylene-vinyl acetate copolymer resin containing maleic anhydride. , Heat resistant, oil resistant resin composition. delete The method of claim 1, The rigidity, heat resistance, oil-resistant resin composition, Based on 100 parts by weight of the polyester base resin 0.5 to 10 parts by weight of antioxidant; 1 to 10 parts by weight of the crosslinking aid; And Stiffness, heat resistance, oil-resistant resin composition characterized in that it further comprises any one or two or more additives selected from the group consisting of 0.5 to 10 parts by weight of the lubricant. The method of claim 3, The antioxidant is a rigid, heat-resistant, oil-resistant resin composition, characterized in that any one selected from the thioester-based material and the phenol-based material or a mixture of two or more selected from these. A rigid, heat resistant and oil resistant heat shrink tube, which is prepared using the rigid, heat resistant and oil resistant resin composition according to any one of claims 1 and 3 to 4.