JP2018197292A - Polyvinyl chloride-based heat shrinkable tube, wire by coating tube, coil, and cable - Google Patents

Abstract

To provide a polyvinyl chloride-based heat shrinkable tube excellent in bloom resistance, bleeding resistance, heat stability, and flexibility.SOLUTION: There is provided a polyvinyl chloride-based heat shrinkable tube mainly containing a resin composition by blending 100 pts.mass of a polyvinyl chloride-based resin (A), 0.1 to 5.0 pts.mass of a methyl tin-based compound (B), and 20 to 70 pts.mass of a plasticizer (C) having solubility parameter in a range of 8.7 to 10.0 (cal/ml).SELECTED DRAWING: None

Description

  The present invention relates to a polyvinyl chloride heat-shrinkable tube excellent in bleed resistance, bloom resistance, thermal stability and flexibility.

  Polyvinyl chloride heat-shrinkable tubes are widely used for covering applications such as automobile harnesses, electric wires and cables, and electrical insulation applications such as capacitors and secondary batteries because of their excellent mechanical properties and economy.

  Polyvinyl chloride resin, on the other hand, decomposes and degrades mainly due to the dehydrochlorination reaction due to the effects of heat, light, oxygen, etc. during the production of polymers, the processing of molded products such as films and sheets, or during use. Cause coloration. Therefore, it is necessary to blend stabilizers such as lead compounds, tin compounds, fatty acid metal salts, or non-metallic compounds such as epoxy compounds, phenol compounds, and polyols.

  In order to impart flexibility to the polyvinyl chloride resin, a method of blending a plasticizer represented by di-2-ethylhexyl phthalate is generally used. However, when blending a large amount of plasticizer, stabilizer bloom and plasticizer bleed often become problems, and it is difficult to suppress both stabilizer bloom and plasticizer bleed in the prior art. Met. In order to solve such a problem, for example, Patent Document 1 discloses a resin composition using a plasticizer having a specific structure.

Japanese Unexamined Patent Publication No. 2016-44298

  Although the technique of Patent Document 1 has improved bloom resistance and bleed resistance at about 70 ° C., the heat-shrinkable tube has a quality that can withstand long-term use in an environment exceeding 100 ° C. Therefore, such a conventional technique provides a polyvinyl chloride heat-shrinkable tube excellent in both bleed resistance and bloom resistance when used at a high temperature level required for a heat-shrinkable tube. It was difficult.

  As a result of intensive studies to solve the above-mentioned problems, the present inventor blended a specific stabilizer and a specific plasticizer with respect to the polyvinyl chloride resin, thereby preventing bleeding resistance, bloom resistance, The present inventors have found that a polyvinyl chloride heat-shrinkable tube having excellent thermal stability can be realized, and have completed the present invention.

That is, the invention is based on 100 parts by mass of the polyvinyl chloride resin (A), 0.1 to 5.0 parts by mass of the methyltin compound (B), and a solubility parameter of 8.7 to 10.0 ( cal / ml) A polyvinyl chloride heat-shrinkable tube comprising a resin composition containing 20 to 70 parts by mass of a plasticizer (C) in a range of ^1/2 as a main component.

  According to the present invention, a polyvinyl chloride heat-shrinkable tube excellent in bloom resistance, bleed resistance, thermal stability, and flexibility can be obtained, so that it can be used for covering automobile harnesses, electric wires, windings, cables, etc. Alternatively, it is possible to provide a heat-shrinkable tube suitable for electrical insulation coating applications such as capacitors and secondary batteries.

  Embodiments of the polyvinyl chloride heat-shrinkable tube of the present invention (hereinafter referred to as “the tube of the present invention”) will be described below.

<Polyvinyl chloride resin (A)>
As the polyvinyl chloride resin (A) used in the present invention, a vinyl chloride resin having an arbitrary average degree of polymerization can be used. Preferably, the average degree of polymerization of the polyvinyl chloride resin (A) is 1300 to 4000. If the average degree of polymerization is 1300 or more, sufficient mechanical strength can be obtained. On the other hand, if the average degree of polymerization is 4000 or less, heat generation due to an increase in melt viscosity does not occur, and the occurrence of coloring due to decomposition can be eliminated.
Therefore, from such a viewpoint, the average degree of polymerization of the polyvinyl chloride resin (A) is more preferably 1500 or more, or 3800 or less, particularly within the above-mentioned range, and among these, 1700 or more or 3600 or less. More preferably.

  As the polyvinyl chloride resin (A), in addition to a homopolymer of vinyl chloride (referred to as “vinyl chloride homopolymer”), a copolymer with a monomer copolymerizable with vinyl chloride (hereinafter referred to as “vinyl chloride homopolymer”). , A “vinyl chloride copolymer”), a graft copolymer obtained by graft copolymerization of vinyl chloride with a polymer other than this vinyl chloride copolymer (hereinafter referred to as a vinyl chloride graft copolymer), etc. Can be mentioned.

The vinyl chloride copolymer has a mechanical property that decreases as the content of constituent units other than vinyl chloride in the copolymer increases. Therefore, the proportion of vinyl chloride in the vinyl chloride copolymer is 60 to 60%. It is preferable that it is 99 mass%.
The vinyl chloride homopolymer and the vinyl chloride copolymer can be polymerized by an arbitrary method such as an emulsion polymerization method or a suspension polymerization method.

  Here, the monomer copolymerizable with the polyvinyl chloride resin may be any monomer having a reactive double bond in the molecule. For example, α-olefins such as ethylene, propylene and butylene, vinyl esters such as vinyl acetate and vinyl propionate, vinyl ethers such as butyl vinyl ether and cetyl vinyl ether; unsaturated carboxylic acids such as acrylic acid and methacrylic acid, methyl acrylate , Esters of acrylic acid or methacrylic acid such as ethyl methacrylate and phenyl methacrylate, aromatic vinyls such as styrene and α-methylstyrene, vinyl halides such as vinylidene chloride and vinyl fluoride, N-phenylmaleimide, N-substituted maleimides such as N-cyclohexylmaleimide can be exemplified, and these can be used alone or in combination of two or more.

  As the polymer other than the vinyl chloride copolymer, any polymer that can graft-polymerize vinyl chloride may be used. For example, ethylene / vinyl acetate copolymer, ethylene / vinyl acetate / carbon monoxide copolymer, ethylene / ethyl acrylate copolymer, ethylene / ethyl acrylate / carbon monoxide copolymer, ethylene / methyl methacrylate copolymer, ethylene -A propylene copolymer, an acrylonitrile butadiene copolymer, a polyurethane, chlorinated polyethylene, a chlorinated polypropylene etc. can be mentioned, These can be used individually or in combination of 2 or more types.

<Methyltin compound (B)>
As the methyltin compound (B) used in the present invention, the following compounds can be used. For example, (mono or di) tin (tri or di) hexanoate, (mono or di) methyltin 2-ethylhexanoate, (mono or di) methyltin caprynoate, (mono or di) methyltin laurate, (mono or Fatty acid salt compounds such as di) methyl tin stearate, (mono or di) methyl tin palmitate, (mono or di) methyl tin ethyl maleate, (mono or di) methyl tin isopropyl maleate, (mono or di) methyl tin Butyl malate, (mono or di) methyl tin hexyl malate, (mono or di) methyl tin isooctyl malate, (mono or di) methyl tin 2-ethylhexyl malate, (mono or di) methyl tin tridecyl malate, ( Maleic acid derivatives such as mono or di) methyl tin stearyl malate and (mono or di) methyl tin dodecyl mel Peptide, (mono or di) methyl tin 2-ethylhexyl thioglycolate, and (mono- or di) sulfur-containing compounds such as methyl tin mercaptoethyl oleate and mercaptoethyl thioglycolates like. Among them, it is preferable to use (mono or di) methyl tin mercaptoester such as (mono or di) methyl tin 2-ethylhexyl thioglycolate, and monomethyl tin 2-ethylhexyl thioglycolate and dimethyl tin 2-ethylhexyl thioglycolate It is particularly preferable to use in combination.

<Plasticizer (C)>
The plasticizer used in the present invention preferably has a solubility parameter (SP value) calculated by the Small formula using the Hoy value in the range of 8.7 to 10.0 (cal / ml) ^1/2 . Those in the range of 8.8 to 9.8 (cal / ml) ^1/2 are more preferable, and those in the range of 8.9 to 9.6 (cal / ml) ^1/2 are more preferable. When the solubility parameter of the plasticizer (C) is within the above range, a heat-shrinkable tube having excellent compatibility with the polyvinyl chloride resin (A) and excellent bleed resistance can be obtained.

In the present invention, the “solubility parameter” or “SP value (δ)” is a parameter that determines the activity of each component in a multicomponent system, which is determined based on the theory of Hildebrand's regular solution. There are various calculation methods for the solubility parameter. In the present specification, unless otherwise specified, the solubility parameter is calculated by the Small method using Hoy's constant.
That is, the solubility parameter δ [(cal / ml) ^1/2 ] is calculated by the following equation 1.
δ = d * (ΣG) / M (Formula 1)
Here, d is a density [g / ml], G is a molecular attractive constant [(cal · ml) ^1/2 / mol] of each functional group of Hoy, and M is a molecular weight [g / mol].

Specific examples of the plasticizer (C) having a solubility parameter in the range of 8.7 to 10.0 (cal / ml) ^1/2 include dibutyl phthalate (9.4 (cal / ml) ^1/2 ). Di (2-ethylhexyl) phthalate (8.9 (cal / ml) ^1/2 ), butylbenzyl phthalate (9.9 (cal / ml) ^1/2 ), di (butoxyethyl) phthalate (9.2 ( cal / ml) ^1/2 ), dibutyl adipate (8.9 (cal / ml) ^1/2 ), di (2-ethylhexyl) adipate (8.5 (cal / ml) ^1/2 ), di (butoxyethyl) ) Adipate (8.8 (cal / ml) ^1/2 ), dibutyl sebacate (8.8 (cal / ml) ^1/2 ), tri (2-ethylhexyl) trimellitate (8.9 (cal / ml) ^{1 / 2} ), Epoxidized soybean oil (9.00 (cal / ml) ^1/2 ), tricresyl phosphate (9.7 (cal / ml) ^1/2 ), triethylene glycol di (2-ethyl) butyrate (8.7 (Cal / ml) ^1/2 ), dibutyl carbitol adipate (8.8 (cal / ml) ^1/2 ), methylene bisbutylthioglycolate (9.5 (cal / ml) ^1/2 ), acetyl And tributyl acid (9.0 (cal / ml) ^1/2 ).

  The molecular weight of the plasticizer (C) is preferably 400 or more and 2000 or less, more preferably 450 or more and 1800 or less, and further preferably 500 or more and 1600 or less. If the molecular weight of the plasticizer (C) is within such a range, the flexibility of the polyvinyl chloride resin (A) can be improved without causing excessive bleeding of the plasticizer.

<Combination ratio of each component>
It is preferable that the compounding quantity of the methyl tin-type compound (B) with respect to 100 mass parts of polyvinyl chloride-type resin (A) is 0.1-5.0 mass parts. The lower limit of the compounding amount of the methyltin compound (B) is preferably 0.5 parts by mass or more, and more preferably 1.0 part by mass or more. Moreover, as for the upper limit of the compounding quantity of a methyltin type compound (B), it is more preferable that it is 4.5 mass parts or less, and it is further more preferable that it is 4.0 mass parts or less. If the mixing ratio of the methyltin compound (B) is within such a range, the thermal stability can be improved without deteriorating the moldability of the polyvinyl chloride resin (A).

Moreover, the compounding quantity of the plasticizer (C) in which the solubility parameter with respect to the polyvinyl chloride resin (A) is in the range of 8.7 to 10.0 (cal / ml) ^1/2 is 20 to 70 parts by mass. Is preferred. As for the minimum of the compounding quantity of a plasticizer (C), it is more preferred that it is 30 mass parts or more, and it is still more preferred that it is 40 mass parts or more. Moreover, as for the upper limit of the compounding quantity of a plasticizer (C), it is more preferable that it is 60 mass parts or less, and it is further more preferable that it is 50 mass parts or less. When the blending amount of the plasticizer (C) is within such a range, flexibility can be imparted to the polyvinyl chloride resin (A) while maintaining dimensional stability that is not problematic in practice.

  The resin composition constituting the tube of the present invention includes a heat stabilizer, an antioxidant, an ultraviolet absorber, a light stabilizer, an antibacterial / antifungal agent, an antistatic agent, as long as the effects of the present invention are not impaired. Additives such as lubricants, pigments and dyes can also be blended.

<Flexibility>
As for the flexibility of the tube of the present invention, the storage elastic modulus was measured under the conditions of vibration frequency: 10 Hz, heating rate: 3 ° C./min, and strain: 0.1%. It can represent with the storage elastic modulus in 23 degreeC, and it is preferable that the said storage elastic modulus is 100 MPa-1000 MPa. When the storage elastic modulus is within the above range, it is preferable because secondary workability such as bending of the article after the tube coating of the present invention is excellent.

<Shrinkage rate>
The tube of the present invention preferably has a contraction rate in the length direction of 0 to 40% after being left in a hot air oven at 98 ± 2 ° C. for 5 minutes. As an upper limit, More preferably, it is 35% or less, More preferably, it is 30% or less. The shrinkage in the radial direction is preferably 20 to 70%. The lower limit is more preferably 25% or more, still more preferably 30% or more, and the upper limit is more preferably 60% or less, still more preferably 50% or less. If the shrinkage rate is within the above range, the appearance after coating can be good, and it can be sufficiently shrunk at a low temperature, which is preferable.

<Method for producing tube>
Although it does not specifically limit as a manufacturing method of the tube of this invention, For example, the mixture of a polyvinyl chloride resin (A), a methyltin type compound (B), a plasticizer (C), and other additives is uniaxial. A preferred method is to melt the raw material using an extruder, extrude an unstretched tube using a round die, and then stretch to obtain a seamless heat-shrinkable tube. In addition, a method in which a film extruded / stretched using a T die or an I die is bonded by fusion, welding, or bonding to form a tube, and further, the tube or film is bonded in a spiral to form a tube. Etc.

Here, the method of extruding an unstretched tube using a round die and then stretching to obtain a heat-shrinkable tube will be described in more detail.
A mixture of the polyvinyl chloride resin (A), the methyltin compound (B), the plasticizer (C), and other additives is melted and kneaded using a single screw extruder, and continuously from a round die. After extrusion, the tube is forcibly cooled to form a substantially unstretched tube. As a means for forced cooling, a method of immersing in low-temperature water, a method using cold air, or the like can be used. Of these, the method of immersing in low-temperature water is effective because of its high cooling efficiency. The substantially unstretched tube may be continuously supplied to the next stretching step, or may be used as a raw material for the next stretching step after being wound into a roll. Especially, the method of supplying a substantially unstretched tube to the next extending process continuously from the point of manufacturing efficiency or thermal efficiency is preferable.

The substantially unstretched tube obtained by the above method is heated to a temperature equal to or higher than the glass transition temperature, and then pressurized with a compressed gas from the inside of the tube and stretched. The stretching method is not particularly limited, but, for example, it is fed from one end of an unstretched tube at a constant speed while applying pressure by a compressed gas to the inside of the tube, and then heated by hot water or an infrared heater, etc. In order to regulate the draw ratio, drawing at a fixed ratio is performed through a cooled cylindrical tube. The temperature conditions and the like are adjusted so that the cylinder tube is stretched at an appropriate position.
The stretched tube cooled by the cylindrical tube is sandwiched by a pair of nip rolls and is taken up and wound as a stretched tube while maintaining the stretching tension. Stretching may be performed in any order in the length direction or the radial direction, but is preferably performed simultaneously.

The stretching conditions are adjusted by the blending ratio of the plasticizer and other additives, the target heat shrinkage rate, and the like.
The stretching ratio in the length direction is determined by the ratio of the feed speed of the unstretched tube and the nip roll speed after stretching, and the stretching ratio in the radial direction is determined by the ratio of the unstretched outer diameter to the stretched tube outer diameter. As another stretching and pressurizing method, a method of maintaining the internal pressure of the compressed gas in which both the unstretched tube feed side and the stretched tube take-up side are sandwiched and sealed between nip rolls can be employed.

  The tube of the present invention is produced by stretching a substantially unstretched tube in the radial direction and the length direction. At this time, the draw ratio in the radial direction is preferably 1.3 to 5.0 times, more preferably 1.4 to 4.8 times, and still more preferably 1.5 to 4.6 times. Although it may be unstretched in the length direction, it is preferably stretched at a magnification in the range of 1.02 times to 2.0 times, preferably 1.5 times or less, more preferably 1.3 times or less. What was obtained was preferable. Here, if the draw ratio in the radial direction of the heat-shrinkable tube is 1.3 times or more, an amount of shrinkage sufficient for coating can be obtained, and if it is 5.0 times or less, the tube breaks during drawing. And a heat-shrinkable tube with good appearance can be obtained.

  The use of the tube of the present invention is excellent in bloom resistance, bleed resistance, thermal stability, and flexibility, and is not particularly limited as long as these properties are required. It can be suitably used for coating applications such as harnesses, electric wires, windings and cables, and electrical insulation applications such as capacitors and secondary batteries.

  Hereinafter, the present invention will be described more specifically with reference to examples and comparative examples. However, the present invention is not limited to the examples and comparative examples. The numerical values in the following examples can be substituted for the numerical values (that is, the upper limit value or the lower limit value) described in the above embodiment.

<Polyvinyl chloride resin (A)>
(A) -1: Trade name TH-2500 (average polymerization degree 2400-2600) of Taiyo PVC Co., Ltd.

<Methyltin compound (B)>
(B) -1: Trade name TVS # AT-1500 of Nitto Kasei Co., Ltd. (monomethyltin 2-ethylhexylthioglycolate / dimethyltin 2-ethylhexylthioglycolate mixture)

<Plasticizer (C)>
(C) -1: Trade name TOTM (tri (2-ethylhexyl) trimellitate, SP value: 8.9 (cal / ml) ^1/2 , weight average molecular weight: 547) of JPLUS Co., Ltd.
(C) -2: Adeka Sizer PN-9302 (trade name of ADEKA) (adipic acid-based polyester compound, SP value: 9.1 (cal / ml) ^1/2 , weight average molecular weight: 1600)

<Lubricant (D)>
(D) -1: Kao Wax 230-2, trade name of Kao Corporation (mixture of oxidized polyethylene wax and citric acid diester compound)

(1) Bleed resistance After a tube having a thickness of 0.25 mm, an outer diameter of 6 mm, and a length of 200 mm was left in a hot air oven at 105 ° C. for 48 hours, the state of the tube surface was subjected to sensory evaluation based on the following criteria. The case where there was no change in the state of the tube surface was marked with ◯, and the case where there was a clear stickiness was marked with ×.

(2) Bloom resistance After a tube having a thickness of 0.25 mm, an outer diameter of 6 mm, and a length of 200 mm was left in a hot air oven at 40 ° C. for 480 hours, the state of the tube surface was subjected to sensory evaluation based on the following criteria. The case where there was no change in the state of the tube surface was indicated by ○, and the case where whitening was observed on the tube surface was indicated by ×.

(3) Thermal stability A 10 mm × 10 mm test piece was cut out from the tube, and the appearance after heating in a hot air oven at 200 ° C. for 60 minutes was visually observed.

(4) Flexibility Using a dynamic viscoelasticity measuring device (trade name of IT Measurement Co., Ltd .: Viscoelastic Spectrometer VA-200), vibration frequency: 10 Hz, heating rate: 3 ° C./min, strain: 0 The storage modulus was measured under the condition of 1%. A storage elastic modulus at 23 ° C. in the range of 100 MPa to 1000 MPa was regarded as acceptable.

Example 1
Using a single screw extruder, a mixture containing (A) -1 at 100 parts by mass, 3 parts of (B) -1, 30 parts of (C) -1 and 1 part of (D) -1 was used. After kneading at a resin temperature of 200 ° C., a tube having a thickness of 0.9 mm and an outer diameter of 4.0 mm was extruded from a round die. Next, the film was stretched at a stretching temperature of 90 ° C. and a stretching ratio of 2.0 times in the radial direction, cooled, folded, and wound into a roll. The obtained tube had a thickness of 0.25 mm and an outer diameter of 6 mm. The obtained tube was evaluated for bleed resistance, bloom resistance, thermal stability and flexibility. The results are shown in Table 1.

(Example 2)
A tube was produced and evaluated in the same manner as in Example 1 except that (A) -1 was changed to 100 parts by mass and (C) -1 was changed to 50 parts. The results are shown in Table 1.

Example 3
The tube was prepared and evaluated in the same manner as in Example 1, except that 40 parts of (C) -2 was blended in place of (C) -1 with respect to 100 parts by mass of (A) -1. . The results are shown in Table 1.

(Comparative Example 1)
In place of the methyltin compound (B), Nitto Kasei Co., Ltd. trade name: TVS # MP-300K (dibutyltin malate ester compound, hereinafter referred to as (M) -1) is used. The tube was prepared and evaluated in the same manner as in Example 1 except that -1 was 100 parts by mass, 3 parts for (M) -1 and 50 parts for (C) -1. The results are shown in Table 1.

(Comparative Example 2)
In place of the methyltin compound (B), a product name of Nitto Kasei Co., Ltd .: TVS # 8831 (dioctyltin mercaptoester compound, hereinafter referred to as (M) -2) is used, and (A) -1 is used. A tube was prepared and evaluated in the same manner as in Example 1 except that 3 parts of (M) -2 and 50 parts of (C) -1 were used with respect to 100 parts by mass. The results are shown in Table 1.

(Comparative Example 3)
In place of the plasticizer (C) having a solubility parameter in the range of 8.7 to 10.0 (cal / ml) ^1/2 , trade name DINA (diisononyl adipate, SP value: 8.5) of J-Plus Co., Ltd. (Cal / ml) ^1/2 , weight average molecular weight: 427, hereinafter referred to as (P) -1), and (A) -1 is 100 parts by mass and (P) -1 is 50 parts. A tube was prepared and evaluated in the same manner as in Example 1 except that. The results are shown in Table 1.

  The tubes obtained in Examples 1 to 3 were excellent in all of bloom resistance, bleed resistance, thermal stability, and flexibility. On the other hand, the tubes of Comparative Examples 1 to 3 that do not satisfy the requirements of the present invention cannot satisfy any quality.

  The polyvinyl chloride heat-shrinkable tube of the present invention is excellent in bloom resistance, bleed resistance, thermal stability and flexibility, and is used for coating harnesses for automobile harnesses, electric wires, windings, cables, capacitors, and the like. It can be suitably used for electrical insulation applications such as secondary batteries.

Claims (5)

0.1 to 5.0 parts by mass of a methyltin compound (B) and a solubility parameter of 8.7 to 10.0 (cal / ml) with respect to 100 parts by mass of the polyvinyl chloride resin (A) A polyvinyl chloride heat-shrinkable tube comprising a resin composition containing 20 to 70 parts by mass of a plasticizer (C) in a range of ^1/2 as a main component.   The polyvinyl chloride heat-shrinkable tube according to claim 1, wherein the (B) is (mono or di) methyltin mercaptoester.   The polyvinyl chloride heat-shrinkable tube according to claim 1 or 2, wherein the weight average molecular weight of (C) is 400 to 2000.   The polyvinyl chloride heat-shrinkable tube according to any one of claims 1 to 3, wherein (C) is tri (2-ethylhexyl) trimellitate.   An electric wire, a winding, and a cable formed by coating the polyvinyl chloride heat-shrinkable tube according to any one of claims 1 to 4.