JPS63179953A - Polymer composition - Google Patents

Abstract

PURPOSE:To obtain the titled composition having excellent color tone, transparency and discoloration resistance and suitable for heat-shrinkable label, etc., by compounding a polymer composed of a conjugated diene and a vinyl aromatic hydrocarbon with specific amounts of an inorganic acid and/or organic acid and a phenolic compound. CONSTITUTION:A polymer having a weight-average molecular weight of 5,000-5,000,000 and produced by polymerizing a conjugated diene and/or a vinyl aromatic hydrocarbon in the presence of an organic lithium compound as an initiator is compounded with (A) 0.05-5 equivalent (based on the above organic lithium compound) of one or more kinds of inorganic acid (e.g. hydrochloric acid) and/or organic acid (e.g. octylic acid) and (B) 0.05-5pts.wt. (based on 100pts.wt. of the polymer) of one or more compounds selected from phenolic compounds expressed by formulas I-III (R1 is 1-4C alkyl; R2 is 2-4C alkenyl; R3 is tert-butyl, etc.; R4 is H, etc.).

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a polymer composition having excellent color tone, transparency and color fastness. [Prior Art] A composition comprising a conjugated diene and a vinyl aromatic hydrocarbon When a block copolymer has a relatively low vinyl aromatic hydrocarbon content, it has the same elasticity at room temperature as vulcanized natural rubber or synthetic rubber without vulcanization, and can be heated at high temperatures. Since it has processability similar to that of plastic resin, it is widely used in the fields of footwear, plastic modification, asphalt, adhesives, etc. In addition, when the vinyl aromatic hydrocarbon content is relatively high, a thermoplastic resin that is transparent and has excellent impact resistance can be obtained, so its usage has increased in recent years, mainly in the food packaging container field, and its applications have also expanded. It is becoming more diverse.

Such block copolymers are generally produced using an organolithium compound as an initiator, and a polymer with good color tone cannot be obtained unless an appropriate reaction termination method is applied after the polymerization reaction is completed. Therefore, several methods have been attempted to improve this drawback. For example, Tokuko Sho 54-267
No. 9 discloses that the hydrocarbon solvent of the active block copolymer is
After adding water/carbon dioxide/phenolic antioxidant
A method of directly desolventizing the solvent by treatment at a temperature in the range of 15G to 200°C is described, Japanese Patent Publication No. 55-7459.
The publication describes a method in which a hydrocarbon solvent for a block copolymer is heated or mixed with heated water and brought into contact with an aqueous solution of an organic acid compound before stripping the solvent. Furthermore, Japanese Patent Application Laid-open No. 168612/1983 describes a method in which boric acid is added to a polymer, and then a stabilizer is added to recover the polymer.

[Problem that the invention seeks to solve]

However, although these methods improve the color tone immediately after production, it is said that after long-term storage, especially in containers such as kraft paper bags or cardboard boxes, yellowing may occur, although the cause is not always clear. There are problems.

Under these circumstances, the present inventors have investigated the possibility of obtaining a polymer that has excellent color tone immediately after production and color fastness during long-term storage in containers such as paper bags or cardboard boxes. As a result of the process, one or two of the inorganic acids and/or organic acids
By combining more than one species with a specific phenolic compound, the objective was achieved and the present invention was completed.

[Means of problem solving]

That is, the present invention provides a polymer obtained by polymerizing a conjugated diene and/or a vinyl aromatic hydrocarbon using an organolithium compound as an initiator, (1) lli or two or more of an inorganic acid and/or an organic acid. 0.05 to 5 equivalents (I) of the following general formula CI), [II] and (III) to the organolithium compound used as a polymer initiator.
0.05 to 5 parts by weight per 100 parts by weight of the polymer of at least one selected from the phenolic compounds represented by (in the above formula, R□ is an alkyl group having 1 to 4 carbon atoms, R
2 is an alkenyl group having 2 to 4 carbon atoms, R3 is a tert-butyl group or a cyclohexyl group, and R4 is hydrogen or a carbon number 1
~18 alkyl groups.

) A total of polymer compositions are provided.

The present invention will be explained in detail below.

The polymer used in the present invention is produced by polymerizing a conjugated diene and/or a vinyl aromatic hydrocarbon in a hydrocarbon solvent using an organolithium compound as an initiator. Polymers of conjugated dienes or vinyl aromatic hydrocarbons can be produced by any known method, including anionic polymerization of conjugated dienes or vinyl aromatic hydrocarbons with an organolithium compound in an inert hydrocarbon solvent. It can be manufactured by

When a conjugated diene and a vinyl aromatic hydrocarbon are used as monomers, the composition ratio of the conjugated diene and the vinyl aromatic hydrocarbon in the resulting polymer is not particularly limited, but generally 1'l:
99.9:0.1-0.1:99.9, preferably 98=2 to 5:95. The polymer consisting of a conjugated diene and a vinyl aromatic hydrocarbon may be a random copolymer or a block copolymer, and can be prepared by any known method in an inert hydrocarbon solvent. It can be produced by p anion polymerization using a lithium compound.

For example, random copolymers can be made by feeding a mixture of a conjugated diene and a vinyl aromatic hydrocarbon to a polymerization vessel at a slower than normal polymerization rate, as described in U.S. Pat. No. 3,094,514. . Alternatively, as described in U.S. Pat. No. 3,451,988, a random copolymer is produced by copolymerizing a mixture of a conjugated diene and a vinyl aromatic hydrocarbon in the presence of a polar compound or a randomizing agent, which will be described later. be able to.

On the other hand, methods for producing block copolymers include, for example, Japanese Patent Publications No. 36-19286 and Japanese Patent Publication No. 43-17979.
Publication No. 46-32415, Special Publication No. 1973
Examples include the methods described in Japanese Patent Publication No. 36957, Japanese Patent Publication No. 48-2423, Japanese Patent Publication No. 4g-4106, Japanese Patent Publication No. 28925-1982, Japanese Patent Publication No. 49567-1987, and the like. By these methods, a one-block copolymer can be produced using the general formula: (A-B)n, A+B-A)n, B(-A-B)n (in the above formula, A is mainly a vinyl aromatic hydrocarbon). In the polymer block 17, B is a polymer block mainly containing a conjugated diene.The boundary between the A block and the B block does not necessarily have to be clearly distinguished.Also, n is an integer of 1 or more. ) or the general formula, ((B-A) total i■X, [: (A-B)n
:3. ,〒X((B-A) BtoX, [(A-B)
nAdn m+1 (In the above formula, A and B are the same as above, and X is a residue of a coupling agent such as silicon tetrachloride, tin tetrachloride, or epoxidized soybean oil, or an initiator such as a polyfunctional organolithium compound. It is obtained as a block copolymer represented by the following formula (where m and n are integers of 1 or more).

In the above formula, the polymer block mainly composed of vinyl aromatic hydrocarbons refers to a copolymer block of vinyl aromatic hydrocarbons and conjugated diene containing 50% by weight or more of vinyl aromatic hydrocarbons and/or vinyl It refers to an aromatic hydrocarbon homopolymer block, and a polymer block mainly composed of conjugated diene refers to a copolymer block of a conjugated diene and a vinyl aromatic hydrocarbon containing a conjugated diene in an amount exceeding 50% by weight. Or a conjugated diene homopolymer block.

The vinyl aromatic hydrocarbons in the copolymer block may be uniformly distributed or tapered. Further, the copolymer portion may include a plurality of portions in which vinyl aromatic hydrocarbons are uniformly distributed and/or a plurality of portions in which vinyl aromatic hydrocarbons are distributed in a tapered manner.

The block copolymer thus obtained exhibits properties as a thermoplastic elastomer when the content of vinyl aromatic hydrocarbon is 60% by weight or less, preferably 55% by weight or less,
When the vinyl aromatic hydrocarbon content exceeds 60% by weight, preferably 65% by weight or more, it exhibits properties as a thermoplastic resin.

In the present invention, vinyl aromatic hydrocarbons include styrene, 0-methylstyrene, p-methylstyrene, p-
Examples include tert-butylstyrene, 1,3-dimethylstyrene, α-methylstyrene, vinylnaphthalene, vinylanthracene, and styrene is particularly common. These may be used not only alone, but also as a mixture of two or more.

In the present invention, a conjugated diene is a diolefin having a pair of conjugated double bonds, such as 1,3-butadiene, 2-methyl-1,3-butadiene (isoprene),
Examples include 2,3-dimethyl-1,3-butadiene, 1,3-pentadiene, 1,3-hexadiene, and particularly common ones include 1,3-butadiene and isoprene. These may be used not only alone but also as a mixture of two or more. Hydrocarbon solvents include aliphatic hydrocarbons such as butane, pentane, hexane, impentane, heptane, octane, isooctane, cyclopentane, methyl cyclo Alicyclic hydrocarbons such as pentane, cyclohexane, methylcyclohexane, and ethylcyclohexane, or aromatic hydrocarbons such as benzene, toluene, ethylbenzene, and xylene can be used. These may be used not only alone, but also as a mixture of two or more. The organic lithium compound is an organic monolithium compound having one or more lithium atoms bonded in the molecule, such as ethyllithium, n-propyllithium, isopropyllithium, n-butyllithium, 8
Examples include ee-butyllithium, tert-butyllithium, hexamethylene dilithium, butadienyldilithium, and imprenyldilithium. These may be used not only in Otori type but also in combination of two or more types.

In the production of the polymer used in the present invention, the polymerization rate is adjusted, the microstructure (cis, trans, vinyl ratio) of the polymerized conjugated diene moiety is changed, and the reactivity ratio of the conjugated diene and the vinyl aromatic hydrocarbon is adjusted. Polar compounds and randomizing agents can be used for such purposes. Examples of polar compounds and randomizing agents include ethers, amines, thioethers, phosphoramides, alkylbenzene sulfonates, potassium or sodium alkoxides, and the like. Examples of suitable ethers are dimethyl ether, diethyl ether, diphenyl ether and tetrahydrofuran, diethylene glycol dimethyl ether, diethylene glycol dibutyl ether. As the amines, in addition to tertiary amines such as trimethylamine, triethylamine, and tetramethylethylenediamine, cyclic tertiary amines can also be used. Phosphines and phosphoramides include triphenylphosphine and hexamethylphosphoramide. Randomizing agents include potassium or sodium alkylbenzene sulfonate, potassium or sodium butoxide, and the like.

The polymerization temperature for producing the polymer used in the present invention is generally from -1θ°C to 150°C, preferably from 40°C to 1θ°C.
2 G, °C. The time required for polymerization varies depending on the conditions, but is usually within 48 hours, and is particularly preferably 10 to 10 hours. Further, it is desirable to replace the atmosphere of the polymerization system with an inert gas such as nitrogen gas.

The polymerization pressure is not particularly limited, as long as it is within a pressure range sufficient to maintain all of the monomer and solvent in a liquid phase within the above polymerization temperature range. Furthermore, care must be taken to avoid contamination of the polymerization system with impurities that would inactivate the catalyst and living polymer, such as water, oxygen, carbon dioxide, and the like.

The weight average molecular weight of the polymer thus obtained is generally between ooo and 5,000,000, preferably 10.0
00-1. The amount of hydrocarbons in the zero polymer solution, o o o, o o o, is generally from 50 parts by weight to 2000 parts by weight based on 100 parts by weight of the polymer. Depending on the properties of the ζ polymer, the polymer may be insoluble in the hydrocarbon solvent and may be obtained in a suspended state.

The polymer obtained above contains 0.05 to 5 equivalents, preferably 0.05 to 5 equivalents, based on the organolithium compound using one or more of inorganic acids and/or organic acids as an initiator for the polymer. Add 2 to 2 equivalents. If the blending amount of the inorganic acid and/or organic acid is less than the above range, the color tone improvement effect aimed at by the present invention will be insufficient; on the other hand, if it exceeds the above range, the improvement effect beyond the scope of the present invention will not be achieved. This is not preferable because it causes a problem of deterioration of whitening resistance when immersed in hot water.

Inorganic acids used in the present invention include acids formed by bonding hydrogen with acid groups containing nonmetals such as chlorine, sulfur, nitrogen, and phosphorus, such as hydrochloric acid, sulfuric acid, nitric acid, phosphoric acid, and carbonic acid. It will be done. Further, the organic acid used in the present invention is an organic compound having acidity in a broad sense, and includes compounds such as carboxylic acid, sulfonic acid, sulfinic acid, and phenol, but preferably an organic compound containing a carboxyl group. The following are preferred.

(1) Fatty acid having 8 or more carbon atoms (2) Rosin acid (3) Oxycarboxylic acid (4) Aromatic carboxylic acid Specific examples of fatty acids preferably used in the present invention include octylic acid, capric acid, lauric acid, and myristic acid. Acid, palmitic acid, stearic acid, oleic acid, linoleic acid, linoleic acid, ricinoleic acid, behenic acid, castor hydrogenated fatty acid,
Examples include beef tallow fatty acids and mixtures thereof. Rosin acid may also be a hydrogenated product thereof.

The oxycarboxylic acid is a compound having at least one hydroxy group and at least one carboxyl group in the molecule, such as glycolic acid, lactic acid, tartaric acid,
Examples include citric acid, malic acid, oxyvaleric acid, 2-hydroxystearic acid, salicylic acid, 0-oxycinnamic acid, and mixtures thereof. Aromatic carboxylic acids include benzoic acid, chlorobenzoic acid, aminobenzoic acid,
Examples include cinnamic acid, phenylacetic acid, and mixtures thereof.

In the present invention, organic acids are preferable to inorganic acids in terms of whitening resistance during immersion in hot water. In particular, it is recommended to blend one or more organic acids in the substantial absence of water in order to obtain a composition with excellent hot water whitening resistance. Here, blending in the substantial absence of water means that the organic acid is not dissolved in a large amount of water and added. Specifically, it is used as an initiator for the polymer. This means adding water in an amount of 10 equivalents or less, preferably 5 equivalents or less relative to the organic lithium compound. In addition, when the organic acid coexists with water in the form of water of crystallization, etc., the addition state is assumed to be carried out in the substantial absence of water.

In the present invention, a stopper may be added before or simultaneously with the inorganic acid and/or organic acid. As the terminator, known terminators capable of deactivating living polymers produced by organolithium compounds, such as compounds having active hydrogen, can be used, but suitable ones include water, alcohol (methanol, ethanol, gropanol). etc.), polyhydric alcohols (ethylene glycol,
propylene glycol, glycerin, etc.), primary amines, secondary amines, and mixtures thereof.

These are generally 0.01 parts by weight per 100 parts by weight of the polymer.
It is used in a range of 10 parts by weight.

Next, the phenolic compound used in the present invention is at least one selected from the phenolic compounds represented by the general formulas [E], [II], and [[].

Specific examples of the substituent R0 include a methyl group, an ethyl group, a propyl group, an isobutyl group, and a tert-butyl group, with a methyl group or a tert-'butyl group being particularly preferred. R2 is an alkenyl group having 2 to 4 carbon atoms, and specific examples thereof include an ethynyl group, an isopropenyl group, a propenyl group, an isobutenyl group, a butenyl group, and the like. Particularly preferred is an ethynyl group. Preferred R1 is a tert-butyl group. Specific examples of the substituent R4 include a hydrogen methyl group, an ethyl group, a propyl group, and a butyl group, with hydrogen or a methyl group being particularly preferred. The above phenolic compound is 0.05 to 5 parts by weight per 100 parts by weight of the polymer,
It is preferably used in an amount of 0.1 to 2 parts by weight. If the amount of the phenolic compound is less than 0.05 parts by weight, it is not preferable because stability during high-temperature processing is poor, gelation occurs, and color tone deteriorates. On the other hand, even if the amount exceeds 5 parts by weight, the improvement effect in terms of stability and color tone during high-temperature processing beyond the scope of the present invention will not be exhibited.

In the present invention, at least one kind selected from a phosphorus stabilizer and a sulfur stabilizer is added to the polymer 100 as required.
90.05 to 5 parts by weight, preferably 0.1 to 2 parts by weight
They may be mixed in weight parts. Specific examples of phosphorus stabilizers include tris(nonylphenyl)phosphite, cyclic neopentanetetrylbis(octadecylphosphite), tris(2,4-di-tert-butylphenyl)phosphite), 4.4- Butylidene bis(
3-Methyl-6-tert-butylphenylcytritecyl) phosphite, 4,4'-biphenylene diphosphinic acid tetrakis (2,4-di-tert-butylphenyl), cyclic neopentanetetryrubis (2,4- Examples include di-tert-butylphenyl)7 osphite.

Further, as a specific example of the sulfur stabilizer, dilauryl-3
, 3'-thiodipropionic acid ester, simiristyl-
3,3'-thiodipropionic acid ester, distearyl-3,3', thiodipropionic acid ester, laurylstearyl-3,3'-thiodipropionic acid ester, pentaerythritol-tetrakis-(β-lacryluthioglyceride) robionate), 3,9-bis-(2-dodecylthioethyl)-2,4°8, 1O-tetraoxaspiro(s #5) undecane, and the like.

A preferred method of obtaining the compositions of the invention is in a hydrocarbon solvent:
A polymer solution K obtained by polymerizing a conjugated diene and/or a vinyl aromatic hydrocarbon using an organolithium compound as an initiator. First, one or more inorganic acids and/or organic acids are added, and then in the present invention. A method in which the solvent is removed after adding at least one of the specified phenolic compounds, or a part or the entire amount of the solvent is removed after adding one or more inorganic acids and/or organic acids to the polymer solution. However, there is a method in which at least one of the phenolic compounds defined in the present invention is added thereafter. The solvent may be removed from the polymer solution by any known method, such as heating the solution to evaporate the solvent, dispersing the solution in water or hot water, and blowing water vapor to evaporate the solution (steam). stripping method), a method in which a large amount of a precipitant such as methanol is added to precipitate the polymer and separate it from the solvent;
A method of vacuum drying the solution, a method of evaporating a part of the solvent using a flash tower, etc., and then further removing the solvent using a vented extruder can be adopted.

Various additives can be added to the polymer composition of the present invention depending on the purpose. For example, softeners such as oil, plasticizers, antistatic agents, lubricants, ultraviolet absorbers, H fuels, pigments, inorganic fillers, organic fibers/inorganic fibers, reinforcing agents such as carbon black, and other thermoplastic resins. Can be used as an additive.

The polymer composition of the present invention can be used for various purposes as described below, but a particularly preferred use is to use the polymer composition for 1
Uses include heat-shrinkable films, sheets, etc. obtained by @stretching, biaxial stretching, or multiaxial stretching, and such films, sheets, etc. can be used for plastic molded products, metal products, etc. after printing characters and designs. It can be used as a so-called heat-shrinkable label material, which is used by being tightly attached to the surface of a packaged object such as a glass container or porcelain by heat-shrinking.

Polymers used for such purposes include (1)
It has at least one polymer block mainly composed of a vinyl aromatic hydrocarbon and at least one polymer block mainly composed of a conjugated diene, and the weight ratio of the vinyl aromatic conjugated hydrogen to the conjugated diene is 60. /40 to 9515 as a main component, and for the purpose of improving the impact resistance, rigidity, slipperiness, stretching characteristics, etc. of such block copolymer resin, (1) at least 1 a polymer block mainly composed of vinyl aromatic hydrocarbons and at least one polymer block mainly composed of conjugated diene, the weight ratio of the vinyl aromatic hydrocarbon to the conjugated diene is 10/90 or more, so
A block copolymer elastomer (Iii) having a molecular weight of less than 4o, a non-rubber-modified styrenic polymer (b), and a block copolymer composition in which at least Available.

Block copolymer resins generally have a number average molecular weight of 50.0.
00-500,000, preferably 80,000-35
0,000 can be used. Block copolymer elastomers can also be used as impact modifiers and generally have a number average molecular weight of 20,000 to 250,000. Preferably, 4,000 to 200,000 can be used.

The non-rubber-modified styrenic polymer is the vinyl-substituted aromatic hydrocarbon compound described above or a styrene polymer copolymerizable therewith.
It is obtained by polymerizing. Monomers copolymerizable with vinyl-substituted aromatic hydrocarbon compounds include α-methylstyrene, acrylonitrile, acrylic esters, methacrylic esters, maleic anhydride, etc.Particularly preferred non-rubber modified styrenic polymers include: Polystyrene, styrene-α-methylstyrene copolymer,
Examples include acrylonitrile-styrene copolymer, styrene-methacrylic acid ester copolymer, styrene-maleic anhydride copolymer, and the like, and these can be used alone or in a mixture of two or more.

Rubber-modified styrenic polymers are obtained by polymerizing a mixture of a vinyl-substituted aromatic hydrocarbon compound or a monomer copolymerizable therewith with an elastomer, and polymerization methods include suspension polymerization, emulsion polymerization, bulk polymerization, and bulk polymerization. -Suspension polymerization etc. are commonly carried out. Monomers copolymerizable with vinyl-substituted aromatic hydrocarbon compounds include α-methylstyrene, acrylonitrile, acrylic ester,
Examples include methacrylic acid ester and maleic anhydride. Moreover, natural rubber, synthetic isoprene rubber, butadiene rubber, styrene-butadiene rubber, high styrene rubber, etc. can be used as the nidistomer. These distomers are generally used in an amount of 2 parts by weight per 100 parts by weight of the vinyl-substituted aromatic hydrocarbon compound or the monomer copolymerizable therewith.
~70 parts by weight, more generally 3 to 50 parts by weight, dissolved in the monomer or in latex form for bulk polymerization, bulk-suspension polymerization, emulsion polymerization, etc. Particularly preferred rubber-modified styrenic polymers include high impact rubber-modified styrenic polymers (HIPS).

Non-rubber-modified styrenic polymers can be used as stiffness improvers, and rubber-modified styrenic polymers can be used as stiffness, impact resistance, and lubricity improvers.

The blending amounts of polymers (11) to OV) are as follows: polymer (1) 1
Generally not more than 100 parts by weight per 00 parts by weight,
Preferably it is 0.5 to 50 parts by weight.

To obtain a heat-shrinkable uniaxial, biaxial, or stretched film from the block copolymer resin or block copolymer composition described above, the block copolymer or block copolymer composition is processed by a conventional T-die or cyclic process. 150-250℃, preferably 170-250℃ from the die in 7 rat or tube shape.
Extrusion molding is carried out at 20° C., and the obtained unstretched product is substantially 1-axis stretched, biaxially or multiaxially stretched. For example, in the case of uniaxial stretching, in the case of a film or sheet, it is stretched in the extrusion direction with a calender roll, or in the direction perpendicular to the extrusion direction with a tenter, and in the case of a tube, in the extrusion direction of the tube or in the circumferential direction. Stretch.

In the case of biaxial stretching, in the case of a film or sheet, the extruded film or sheet is stretched in the longitudinal direction with a metal roll, etc., and then stretched in the transverse direction with a tenter, etc., and in the case of a tube, the extruded film or sheet is stretched in the longitudinal direction with a tenter, etc. The tubes are stretched simultaneously or separately in the circumferential direction of the tube, that is, in the direction perpendicular to the tube axis.

Stretching temperature is 60~110℃, preferably 80~Zoo℃
It is preferable to stretch the film in the longitudinal direction and/or the transverse direction at a stretching ratio of 1.5 to 8 times, preferably 2 to 6 times. If the stretching temperature is less than 60°C, breakage occurs during stretching, resulting in a desired heat-shrinkable film, etc., and if it exceeds 110°C, it is difficult to obtain a film with good shrinkage properties. The stretching ratio is selected within the above range to correspond to the shrinkage rate required depending on the application, but if the stretching ratio is less than 1.5 times, the heat shrinkage rate will be 1. , also 8
Stretching ratios exceeding 1:2 are unfavorable in view of stable production in the stretching process. In the case of biaxial stretching, the stretching ratios in the machine direction and the transverse direction may be the same or different. l
Heat-shrinkable films after axial stretching or biaxial stretching are
Then, if necessary, immediately after cooling, heat treatment is performed at 60 to 105°C, preferably 80 to 95°C, for a short time, for example, 3 to 60 seconds, preferably 10 to 40 seconds, to prevent natural shrinkage at room temperature. It is also possible.

In order to use the heat-shrinkable film etc. obtained in this way as a heat-shrinkable packaging material or a heat-shrinkable label material, the heat shrinkage rate at 80°C in the stretching direction is 15% or more, preferably 20%. It should be ~70%, more preferably 30-80%.

If the heat shrinkage rate at 80°C in the stretching direction is less than 15q6, the shrinkage characteristics are poor, so it is necessary to adjust the shrink packaging process to a high temperature and uniformity, or to heat it for a long time, resulting in deterioration or deformation at high temperatures. This is undesirable because it becomes impossible to package such items and shrink wrapping processing capacity decreases. Here, the heat shrinkage rate at 80°C refers to the value obtained by immersing an l-axis stretched or biaxially stretched film, etc., for 5 minutes in a heating medium such as 80°C hot water, silicone oil, or glycerin that does not inhibit the properties of the molded product. This is the heat shrinkage rate of the molded product in each stretching direction. Furthermore, heat-shrinkable films that are uniaxially or biaxially stretched have a tensile modulus of elasticity in the stretching direction of 5,000 Kg/a1 or more, preferably 7,000K.
f/- or more, more preferably 10.0001 Nd or more is suitable for the heat-shrinkable packaging material.

If the tensile modulus in the stretching direction is less than 5,000 V4/ad, it is not preferable because it causes sagging in the shrink wrapping process and normal packaging cannot be performed.

When using l-axis stretched or biaxially stretched film as a heat-shrinkable packaging material, it is necessary to
It can be heat-shrinked by heating at a temperature of 30 to 300°C, preferably 150 to 250°C, for several seconds to several minutes, preferably for 1 to 60 seconds, and more preferably for 2 to 30 seconds.

In addition, when using a heat-shrinkable film obtained by l-axis stretching a block copolymer resin or a block copolymer composition as a heat-shrinkable label material, heat at 80°C in a direction perpendicular to the stretching direction. The shrinkage rate is less than 5 cm, preferably 1
It is preferably 0% or less, more preferably 5% or less. Therefore, substantially l-axis stretching for heat-shrinkable labels means that the heat shrinkage rate at 80°C in the stretching direction is 15 inches or more, and the heat shrinkage rate at 80°C in the direction orthogonal to the stretching direction is less than 15%. It refers to applying a stretching process.

As the heat-shrinkable film, one whose thickness is generally adjusted to a range of 10 to 300 microns, preferably 30 to 100 microns is suitably used.

〔Example〕

EXAMPLES The present invention will be explained in more detail with reference to Examples below.

The block copolymers used in the examples were produced as follows. The weight ratio of polymer to solvent in each of the obtained polymer solutions was 1:4.

[Block copolymer (4)] In a nitrogen gas atmosphere, an n-hexane solution VC containing 15 parts by weight of l,3-butadiene and 20 parts by weight of styrene.
After adding 0.11 parts by weight of n-butyllithium and polymerizing at 70°C for 2 hours, an n-hexane solution containing 45 parts by weight of 1,3-butadiene and 20 parts by weight of styrene was further added and the polymerization was carried out at 70°C for 2 hours. Polymerized. The obtained polymer was a block copolymer having a B-A-B-A structure with a styrene content of 40% by weight.

[Block copolymer (B)]

In a nitrogen gas atmosphere, a cyclohexane solution containing 1 slii part of styrene < 0.11 part of n-butyllithium
Parts by weight were added and polymerized at 70°C for 1 hour, and then a cyclohexane solution containing 70 parts by weight of 1,3-butadiene was added and polymerized at 70°C for 2 hours.

Thereafter, a cyclohexane solution containing 15 parts by weight of styrene was further added, and polymerization was carried out at 70° C. for 1 hour. The obtained polymer was a block copolymer having an ABA structure with a styrene content of 30% by weight.

[Block copolymer (C)]

In a nitrogen gas atmosphere, 0.8 parts by weight of n-butyllithium'io was added to a cyclohexane solution containing 30 parts by weight of styrene and 0.3 parts by weight of tetrahydro-7,
After polymerizing at 70°C for 1 hour, 1,3-butadiene 2
A cyclohexane solution containing 0 parts by weight and 50 parts by weight of styrene was added and polymerized at 70°C for 2 hours. The obtained polymer was a block copolymer having an A-B-A structure with a styrene content of 80% by weight.0 [Block copolymer (b)] In a nitrogen gas atmosphere, 15% by weight of l,3-butadiene was added. n-hexane solution containing 20 parts by weight of styrene and 20 parts by weight of styrene.
- Add 0.07 parts by weight of butyllithium and
After polymerization for an hour, an n-hexane solution containing 15 parts by weight of 1.3-butadiene and 50 parts by weight of styrene and 0.02 part by weight of n-butyllithium were further added, followed by polymerization at 70° C. for 2 hours. The obtained polymer is a mixture consisting of a block copolymer with a B-A-B-A structure and a block copolymer with a B-A structure with a styrene content of 70% by weight. was in suspension.

[Block copolymer (g))]

In a nitrogen gas atmosphere, 0.15 parts by weight of a cyclohexane solution containing 75 parts by weight of styrene was added, and after polymerization at 70°C for 1 hour, a cyclohexane solution containing 25 parts by weight of l,3-butadiene was added. Te7
Polymerization was carried out at 0°C for 2 hours.

Thereafter, 5 parts by weight of epoxidized soybean oil was added to obtain a block copolymer with a radial structure having a styrene content of 75% by weight.

[Block copolymer (g)]

In a nitrogen gas atmosphere, n-hexane solution containing 80 parts by weight of 1,3-butadiene and 20 parts by weight of styrene was added with n-hexane.
- Add 0.08 parts by weight of butyllithium and
Polymerized for hours. The obtained polymer was a block copolymer having a styrene content of 20% by weight and a B-A structure.

Examples 1 to 10 and Comparative Examples 1 to 7 n-butyl in which the inorganic acid and/or organic acid shown in Table 1 was used as a polymer initiator in the solution of the block copolymer (C) produced above. After adding 1.0 equivalent to each lithium compound, the phenolic compounds shown in Table 1 were added, and then the solvent was removed by heating. Each of the obtained polymer compositions was extruded into pellets using a 30 Maφ extruder. The color tone, transparency, and
The color fastness and whitening fastness were measured and the results are shown in Table 1.

As is clear from Table 1, the polymer composition of the present invention has excellent color tone, transparency, color fastness, and whitening resistance.

A polymer composition similar to Example 1 was obtained except that in Example I, the amount of benzoic acid added was 10 equivalents relative to the n-butyllithium compound. The resulting polymer composition had the same performance as the composition of Example 1 in terms of color tone, transparency, and discoloration resistance, but was slightly inferior in whitening resistance with a difference in cloudiness of about IO. Further, a polymer composition similar to that in Example 1 was obtained except that the amount of AO-1 added in Example 1 was 10 parts by weight. The performance of the obtained polymer compositions was equivalent to that of the composition of Example 1.

The following margins (Note 1) The following phenolic compounds were used.

AO-1: In the general formula [E], R4 is a methyl group, R2 is an ethynyl group, R3 is a tert-butyl group, R
A phenolic compound AO-2 in which 4 is hydrogen; in the general formula CI), a phenolic compound AO-a in which R and R3 are a tert-butyl group, R2 is an ethynyl group, and R4 is a methyl group; the general formula [II: In l, R□ is a methyl group, R2 is an ethynyl group, R3 is a tert-butyl group, and R4 is hydrogen; phenolic compound A O"-a; In the general formula (III), R is methyl Phenolic compound AO-5: 2,6-tert-butyl-4-methylphenol AO-6: 2,2'-methylene-bis-(4-methyl-6-tert-butylphenol) AO-7 ; 4,
4'-thio-bis-(3-methyl-6-tert-butylphenol) AO-8: 4,4'-butylidene-bis-(3-methyl-6-tert-butylphenol) AO-9:) lisnonylphenyl Phosphite AO-10:) Squirrel (
2,4-di-tert-butylphenyl) phosphite AO-11: cyclic neopentanetetrylbis(2,4-di-tert-butylphenyl) phosphite AO-12 dilauryl-3,3'-thiodipropionic acid Ester AO-13: Pentaerythritol-tetrakis-(β
- lauryl thiogropionate) The blending amount indicates the amount added to 100 parts by weight of the polymer.

(Note 2) The color tone of the press-formed sheet having a thickness of 2u was examined using a ND-VaB type integrated visual measuring instrument manufactured by Nippon Denshoku Industries Co., Ltd. The larger the b value, the greater the apparent yellowness.

b value is less than 5 ◎ b value is 5 to I00 b value is greater than 10'i

6 degrees is less than 5 ◎ 6 degrees is 5 to 10 0 6 degrees is more than 10 death,
Thereafter, the package was opened and the color tone of each molded sheet was measured in the same manner as described above (Note 2).

(Note 5) After leaving the test piece in a desiccator filled with water for 7 days without direct contact with water, the 6 degrees of each test piece was measured in accordance with ASTM D-1003. The devitrification resistance was determined by determining the difference from 6 degrees of the test piece of each polymer obtained by adding only 10% of the polymer and removing the solvent. The larger this difference is, the worse the devitrification resistance is.

Difference in 6 degrees is less than +5 ◎ Difference in a degree is +5 to +15 0 Difference in 6 degrees is more than +15 could not.

Examples 11-20 After adding the inorganic acid and/or organic acid shown in Table 2 to the block copolymer shown in Table 2, block copolymer 1
0.5 parts by weight of AO-1 to 00 parts by weight, AO-9
1.0 part by weight of was added, and then the solvent was removed by heating.

Each of the obtained polymer compositions was extruded using a 30 mm diameter extruder to form pellets. The properties of the obtained pellets are shown in Table 2. In Examples 12 to 14, the amount of water contained in the inorganic acid was 10% based on the n-butyllithium used in the polymerization.
The amount exceeded the equivalent amount.

Example 21 In a nitrogen gas atmosphere, 0.07 parts by weight of n-butyllithium and 0.4 parts by weight of tetramethylethylenediamine were added to n-hexane containing 75 parts by weight of 1,3-butadiene and 25 parts by weight of styrene. and polymerized at 50°C for 6 hours. After adding stearic acid in an amount of 1.0 equivalent to n-butyllithium using stearic acid, AO- 4 to 1.0
After that, the polymer solution was heated to about 120° C. and the solvent was removed in a flash tower until the remaining solvent was 20 parts by weight or less (vc based on 100 parts by weight of the polymer).

Thereafter, this polymer was extruded using a vent extruder, and at the same time, the remaining solvent was removed from the vent section. The thus obtained polymer had good color tone, transparency, and discoloration resistance.

Example 22 In a nitrogen gas atmosphere, 1cn-butyllithium in n-hexane containing 100 parts by weight of 1,3-butadiene was mixed with 0.1 cn-butyllithium.
05 parts by weight was added and polymerized at 70°C for 4 hours. After adding 0.5 equivalent to n-butyllithium using behenic acid to the obtained polymer solution, 0.1 part by weight of AO-1 and 0 part by weight of AO-3 were added to 100 parts by weight of the polymer. .1 part by weight was added, and then the solvent was removed by heating. This polybutadiene was excellent in color tone, transparency, and color fastness.

Example 23 In a nitrogen gas atmosphere, n-butyllithium was added to a cyclohexane solution containing styrene and polymerized at 70°C for 2 hours to obtain polystyrene having a weight average molecular weight of about 200,000. After adding 0.8 vortex amount to n-butyllithium using benzoic acid to the obtained polymer solution, polymer 10
0.2 parts by weight of AO-2 was added to 0 parts by weight, and then the solvent was removed by heating. The obtained polystyrene was excellent in color tone, transparency, color fastness, and whitening resistance.

Example 24 and Comparative Example 8 50 parts by weight of the block copolymer composition of Example 5, Example 1
50 parts by weight of the block copolymer composition of Example 1, 10 parts by weight of the block copolymer composition of Example 18, polystyrene lO
Parts by weight, rubber-modified high-impact polystyrene (If (IPS)
40.) of a polymer mixture consisting of 2 parts by weight. Formed into a sheet with a thickness of o and 25 mm at 200'C using a φ extruder,
After that, it was stretched uniaxially on the horizontal axis using a tenter to a thickness of about 50 mm.
A heat-shrinkable film of μ was produced. At this time, the temperature inside the tenter was set at about 90°C. The tensile modulus of the obtained film in the stretching direction was txooo4/d, the heat shrinkage rate at 80°C in the stretching direction was 45 cm, and the heat shrinkage rate at 80°C in the direction perpendicular to the stretching direction was less than 5qlI. Ta.

Next, after printing letters and patterns on the heat-shrinkable film of the polymer mixture obtained as described above, a cylinder is formed with the stretched direction in the circumferential direction and the non-stretched direction in the longitudinal direction. A heat-shrinkable label with a shape of
The material was heat-shrinked by passing through a shrinkage tunnel whose temperature was controlled at 0°C. The passage time through the shrink tunnel was controlled so that each heat-shrinkable label was in tight contact with the glass bottle surface, and a good coated product was obtained.

The glass bottle-covered product barreled in this manner was stored in a commercially available cardboard box for about 3 months, but no yellowing was observed.

On the other hand, the block copolymer composition of Comparative Example 1 was used instead of the block copolymer composition of Example 5, and
The above except that in place of the block copolymer compositions Nos. 1 and 18, compositions in which block copolymers (E) and (3) were respectively subjected to the same treatment as the block copolymer composition of Comparative Example 1 were used. A similar polymer mixture was prepared, and a coated article using the heat-shrinkable film was obtained in the same manner as above. When the coated product was stored under the same conditions as above, it was observed that it had turned yellow.

〔Effect of the invention〕

The polymer composition of the present invention is transparent and has excellent color tone, 1liil discoloration resistance, and especially yellowing resistance when stored for a long period of time in containers such as kraft paper bags or cardboard boxes, so it can be used to take advantage of these characteristics. It can be used as a wide variety of molded products such as sheets, films, injection molded products of various shapes, blow molded products, pressure molded products, vacuum molded products, etc., as well as modification materials for various thermoplastic resins, materials for footwear, adhesives, etc. Can be used for adhesive materials, asphalt modification materials, electric wire and cable materials, vulcanized rubber materials, vulcanized rubber modification materials, materials for home appliances, automobile parts, industrial parts, household goods, toys, etc. . In particular, the polymer composition of the present invention containing an organic acid in the substantial absence of water,
Because it has excellent whitening resistance when immersed in hot water, it can be used in humid atmospheres and is suitable for applications that come into contact with water, such as food containers, food packaging materials, packaging materials for food containers, toys, medical supplies, etc. Can be used effectively. In particular, the polymer composition of the present invention is suitable for use in heat-shrinkable labels that require excellent color tone, color fastness, and whitening resistance.

Claims (1)

[Scope of Claims] A polymer obtained by polymerizing a conjugated diene and/or a vinyl aromatic hydrocarbon using an organolithium compound as an initiator, and (i) one or more inorganic acids and/or organic acids. 0.05 to 5 equivalents to the organolithium compound used as a polymer initiator (ii) At least one phenolic compound selected from the following general formulas [I], [II] and [III] 0.05 to 5 parts by weight per 100 parts by weight of the polymer ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ [I] ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ [II] ▲ There are mathematical formulas, chemical formulas, tables, etc. Yes▼[III] (In the above formula, R_1 is an alkyl group having 1 to 4 carbon atoms,
R_2 is an alkenyl group having 2 to 4 carbon atoms, R_3 is ter
t-butyl group or cyclohexyl group, R_4 represents hydrogen or an alkyl group having 1 to 18 carbon atoms. ) A polymer composition characterized by blending