JP2020196256A - Method of recovering shape of resin molded product - Google Patents

Abstract

To provide a method for recovering an original shape of a resin molded product containing a resin composition capable of maintaining a stretched state by using a simple method.SOLUTION: There is provided a method for recovering a shape of a resin molded product in a stretched state by heating the same to 35°C or higher and 150°C or lower to return the product into an original state before stretching, in which the resin molded product contains a conjugated diene unit, a non-conjugated olefin unit and an aromatic vinyl unit, and the resin molded product comprises a resin composition containing a copolymer having a butylene unit content of 0 mol%.SELECTED DRAWING: None

Description

The present invention relates to a method for recovering the shape of a resin molded product.

Conventionally, various resin molded products have been manufactured using polypropylene-based resins having excellent impact resistance, chemical resistance, and the like.
For example, from the viewpoint of obtaining a polypropylene-based resin composition suitable for use as an unpainted resin molding material by having scratch resistance compatible with impact resistance, the polypropylene resin has a styrene content of 75 to 90% by weight. 18-42% by weight of hydrogenated styrene / butadiene / styrene copolymer elastomer (A) 7 to 15% by weight and hydrogenated styrene / butadiene / styrene copolymer elastomer (B) having a styrene content of 12 to 15% by weight. ) 3 to 10% by weight of a polypropylene-based resin composition is disclosed (see, for example, Patent Document 1).
Further, from the viewpoint of obtaining a resin product having high impact resistance and transparency, it is a multi-component copolymer containing a conjugated diene unit, a non-conjugated olefin unit, and an aromatic vinyl unit, and is an aromatic vinyl unit. A resin composition containing a multi-component copolymer having a content of 50 mol% or more and less than 100 mol% of the total multi-dimensional copolymer is disclosed (see, for example, Patent Document 2).

Japanese Unexamined Patent Publication No. 2012-246366 International Publication No. 2017/065300

Once a thermoplastic resin such as a polypropylene resin is heat-molded, its shape is maintained. It can be deformed into another shape by reheating, but it does not return to the state before deformation. Similarly, when a thermosetting resin is heat-cured, its shape is maintained, and even after reheating, it does not return to the state before deformation. That is, these resins do not have shape reversibility. For example, if a resin molded product made of a thermoplastic resin or a thermosetting resin is deformed by an external impact during use, the entire molded product must be replaced, resulting in high replacement cost. There is also the problem of disposal of replacements.
On the other hand, the hydrogenated styrene-butadiene-styrene copolymer elastomer (hereinafter referred to as SEBS) has a property of returning to its original shape without maintaining its shape when released from the stretched state.

An object of the present invention is to provide a method for restoring a resin molded product containing a resin composition capable of maintaining a stretched state to its original shape by a simple method.

As a result of examination by the present inventors, a resin composition containing a copolymer containing a conjugated diene unit, a non-conjugated olefin unit, and an aromatic vinyl unit and having a butylene unit content of 0 mol% is thermally produced. Unlike elastomers such as thermoplastic resins, thermosetting resins, and SEBS, the stretched state is maintained, but the present invention has been found that the stretched state is restored by heating (that is, the shape is reversible). It was completed.

In order to solve the above problems, the present invention provides the following [1] to [4].
[1] A method for recovering the shape of a resin molded product in a stretched state by heating it to 35 ° C. or higher and 150 ° C. or lower to return it to the state before stretching. The resin molded product is a conjugated diene unit. A method for recovering the shape of a resin molded product comprising a resin composition containing a non-conjugated olefin unit and an aromatic vinyl unit and containing a copolymer having a butylene unit content of 0 mol%.
[2] The copolymer has a conjugated diene unit content of 2 to 90 mol%, a non-conjugated olefin unit content of 2 to 98 mol%, and an aromatic vinyl unit content of 0. The method for recovering the shape of the resin molded product according to [1], which is 1 to 50 mol%.
[3] The method for recovering the shape of a resin molded product according to [1] or [2], wherein the resin molded product is stretched to a stress of 4 MPa or more and 60 MPa or less and then heated.
[4] The method for recovering the shape of a resin molded product according to [1] or [2], wherein the resin molded product having a draw ratio of 300% or more and 700% or less is heated.

According to the present invention, it is possible to provide a method capable of easily restoring a stretched resin molded product to its original shape with respect to a resin molded product containing a specific resin composition.

It is a schematic diagram of the test piece used for the shape recovery evaluation.

The present invention is a method for recovering the shape of a resin molded product in a stretched state by heating it to 35 ° C. or higher and 150 ° C. or lower to return it to the state before stretching. The resin molded product is a conjugated diene. It comprises a resin composition containing a unit, a non-conjugated olefin unit, an aromatic vinyl unit, and a copolymer having a butylene unit content of 0 mol%.
In addition, the notation of the numerical range of "AA to BB" in this specification means "AA or more and BB or less".

[Resin molded product]
The resin molded product in the present invention is made by using a resin composition containing a copolymer. The copolymer will be described in detail later.

The resin composition in the present invention is molded into a desired shape according to the intended use.
The resin molded product in the present invention includes, for example, tires, automobile parts (automobile structures (bumpers, chassis, front grille, etc.), automobile seats, automobile batteries (lithium ion batteries, etc.), weather strips, hose tubes, etc. , Anti-vibration rubbers, cables, sealing materials, paint binders, etc.).
In addition, the resin molded products of the present invention include conveyor belts, crawlers, resin pipes, sound absorbing materials, bedding, precision parts for office equipment (OA rollers, etc.), bicycle frames, golf balls, tennis rackets, golf shafts, and the like.
Further, the resin molded product of the present invention includes filters, adhesives, adhesives, inks, medical instruments (medical tubes, bags, microneedles, rubber sleeves, artificial organs, caps, packings, injector gaskets, drug stoppers, artificial legs, etc. Prosthesis, etc.), cosmetics (UV powder, puffs, containers, wax, shampoo, conditioners, etc.), detergents, building materials (floor materials, seismic control rubber, seismic isolation rubber, building films, sound absorbing materials, waterproof sheets, etc.), packaging materials , Liquid crystal material, organic EL material, organic semiconductor material, electronic material, electronic device, communication equipment, aircraft parts, mechanical parts, electronic parts, agricultural materials, fibers (wearable base), resin piping, daily necessities (toothbrush, shoe sole, Glasses, artificial bait, binoculars, toys, dust masks, garden hoses, etc.), robot parts, optical parts, road materials (asphalt, guard rails, poles, signs, etc.), protective equipment (shoes, bulletproof waistcoats, etc.), electrical equipment exterior parts, It can be an OA exterior part, a sole, a sealing material, or the like.
In the above, OA means office automation, UV means ultraviolet, and EL means electro-luminescence.

The resin molded product applicable to the present invention is required to be in a stretched state when the above heating is performed, but it does not matter whether or not the resin molded product is stretched at the manufacturing stage. For example, the resin molded product may be a fiber or a film stretched at the manufacturing stage. Alternatively, a resin molded product formed by injection molding, extrusion molding, press molding or the like may be deformed and stretched by some external pressure (collision, load application, etc.) during use.

As a stretching method at the production stage (for example, a fiber stretching method or a film stretching method), a known method can be applied. Further, a known method can be applied to the production of resin molded products such as injection molding, extrusion molding, and press molding.

The resin molded product applicable to the present invention exhibits excellent mechanical properties such as high impact resistance and high tensile strength, and in a normal use environment such as about room temperature (for example, 5 to 30 ° C.) after stretching. , The stretched state can be maintained. "Maintaining the stretched state" means not only when the stretched length is maintained as it is when the resin is stretched and then released by grasping it with an instrument such as a chuck or by hand, but also while shrinking after the release. Also includes cases where the state before stretching is not completely restored and the stretched state is maintained to some extent.

The stretched state of the resin molded product is not particularly limited, but the resin molded product before heating is preferably stretched to a stress of 4 MPa or more and 60 MPa or less, and is stretched to a stress of 5 MPa or more and 50 MPa or less. It is more preferable to have.
Further, the resin molded product before heating is preferably stretched to a draw ratio of 300% or more and 700% or less, and more preferably 400% or more and 700% or less.

[Shape recovery of stretched resin molded products]
The resin molded product deformed by the stretching can be restored to a shape substantially equal to or close to the size before stretching by placing it in a heating environment. Specifically, the heating temperature is 35 ° C. or higher and 150 ° C. or lower. The heating temperature is 10 ° C. or higher higher than the melting point of the component having the highest melting point among the components contained in the resin molded product (copolymer described later and “other components” described later). It is preferable to do so. For example, the heating temperature is more preferably 50 ° C. or higher and 120 ° C. or lower, and further preferably 65 ° C. or higher and 95 ° C. or lower.
The stretched resin molded product may be heated by putting it in an oven or by blowing warm air, or by heating a liquid (for example, water) that does not dissolve the resin molded product. It may be immersed in and heated.
From the viewpoint of simply and evenly heating the molded product, the stretched resin molded product is preferably heated by immersing the stretched resin molded product in water adjusted to the above-mentioned temperature.
The heating time is not particularly limited, but it is preferable to recover in about 5 seconds to 20 minutes in consideration of the treatment efficiency.
The present invention has an advantage that it is very simple in that it can be restored to a shape close to the original state by heating at a relatively low temperature of 35 ° C. or higher and 150 ° C. or lower.

[Application example]
The shape recovery method of the present invention can be applied to, for example, the following applications.
(1) By heating guardrails, signs, etc. that have been deformed due to a collision with an automobile, etc., the shape before the collision is restored.
(2) By heating tires and automobile parts (for example, bumpers, chassis, etc.) that have been deformed by a collision, they are restored to their original state.
(3) The original state is restored by heating the bicycle frame, helmet, etc. that have been deformed due to the collision.
(4) Daily necessities (toothbrushes, eyeglasses, bathtubs, etc.) deformed by load application or impact are restored to their original state by heating.
(5) The stretched resin pipe is inserted into a metal pipe having a larger diameter and then heated. As a result, the inside of the metal pipe is lined.
(6) Wear shoes, artificial limbs, artificial legs, etc. in a deformed state and heat them to improve the fit.
(7) The original shape is restored by heating the paint that has been deformed by use.

[Copolymer]
The copolymer contains a conjugated diene unit, a non-conjugated olefin unit, and an aromatic vinyl unit, and the content of the butylene unit is 0 mol% (hereinafter, it may be referred to as "copolymer in the present invention"). is there).
As the hydrogenated styrene-butadiene-styrene copolymer elastomer used in Patent Document 1, a hydrogenated styrene-ethylene-butylene-styrene copolymer (SEBS) containing a butylene unit is used. The copolymer in the present invention has a butylene unit content of 0 mol%, and the copolymer in the present invention does not contain SEBS.

The copolymer in the present invention contains at least a conjugated diene unit, a non-conjugated olefin unit, and an aromatic vinyl unit, but is composed of only a conjugated diene unit, a non-conjugated olefin unit, and an aromatic vinyl unit. Alternatively, it may contain a monomer unit other than the butylene unit.

When the copolymer of the present invention contains only three units of a conjugated diene unit, a non-conjugated olefin unit, and an aromatic vinyl unit, the copolymer of the present invention is referred to as a "ternary copolymer". Sometimes referred to. "Three elements" means that the copolymer contains three different building blocks. If the copolymer contains three units, a conjugated diene unit, a non-conjugated olefin unit, and an aromatic vinyl unit, plus one or more other units, "quaternary", depending on the number of constituent units. , "Five yuan". Three or more elements are called multiple elements. Therefore, the copolymer of the present invention is a multi-dimensional copolymer containing at least 3 units of a conjugated diene unit, a non-conjugated olefin unit, and an aromatic vinyl unit.

(Conjugated diene unit)
The conjugated diene unit is a structural unit derived from the conjugated diene compound as a monomer.
Here, the conjugated diene compound refers to a conjugated diene compound. The conjugated diene compound preferably has 4 to 8 carbon atoms. Specific examples of such conjugated diene compounds include 1,3-butadiene, isoprene, 1,3-pentadiene, 2,3-dimethyl-1,3-butadiene and the like. The conjugated diene compound may be used alone or in combination of two or more.

The conjugated diene compound as the monomer of the copolymer preferably contains at least one selected from the group consisting of 1,3-butadiene and isoprene, and is selected from the group consisting of 1,3-butadiene and isoprene. It is more preferable that it is composed of at least one of them, and further preferably that it is composed of only 1,3-butadiene.
In other words, the conjugated diene unit in the copolymer preferably contains at least one selected from the group consisting of 1,3-butadiene units and isoprene units, from 1,3-butadiene units and isoprene units. It is more preferable that it consists of at least one selected from the group consisting of 1,3-butadiene units.

The content of the conjugated diene unit of the copolymer is preferably 2 mol% or more, more preferably 5 mol% or more, and further preferably 10 mol% or more. The content of the conjugated diene unit is preferably 90 mol% or less, preferably 85 mol% or less, more preferably 80 mol% or less, more preferably 70 mol% or less, and more preferably 60 mol%. It is more preferably less than or equal to, particularly preferably 50 mol% or less, and even more preferably 40 mol% or less.
When the content of the conjugated diene unit is in the above range, a high-strength copolymer can be obtained, the stretched state can be easily maintained when the resin molded product is stretched, and the recoverability to the shape before stretching after heating is achieved. Can be good.

(Non-conjugated olefin unit)
The non-conjugated olefin unit is a structural unit derived from the non-conjugated olefin compound as a monomer.
Here, the non-conjugated olefin compound refers to an aliphatic unsaturated hydrocarbon having one or more carbon-carbon double bonds. The non-conjugated olefin compound preferably has 2 to 10 carbon atoms. Specific examples of such non-conjugated olefin compounds include α-olefins such as ethylene, propylene, 1-butene, 1-pentene, 1-hexene, 1-heptene and 1-octene, vinyl pivalate and 1-phenylthioethane. , N-Vinylpyrrolidone and other heteroatomic substituted alkene compounds and the like. The non-conjugated olefin compound may be one kind alone or a combination of two or more kinds.

The non-conjugated olefin compound as a monomer of the copolymer is acyclic from the viewpoint of obtaining a high-strength resin molded product, maintaining the stretched state of the resin molded product, and improving the shape recovery after heating. The non-conjugated olefin compound of the above is preferable, and the acyclic non-conjugated olefin compound is more preferably α-olefin, further preferably α-olefin containing ethylene, and is composed of ethylene only. Is particularly preferable.
In other words, the non-conjugated olefin unit in the copolymer is preferably an acyclic non-conjugated olefin unit, and the acyclic non-conjugated olefin unit is preferably an α-olefin unit. It is more preferable that it is an α-olefin unit containing an ethylene unit, and particularly preferably it is composed of only an ethylene unit.

The content of the non-conjugated olefin unit of the copolymer is preferably 2 mol% or more, more preferably 5 mol% or more, more preferably 10 mol% or more, and 20 mol% or more. Is even more preferable, and 30 mol% or more is particularly preferable, and 40 mol% or more is even more preferable. The content of the non-conjugated olefin unit is preferably 98 mol% or less, more preferably 95 mol% or less, and further preferably 90 mol% or less.
When the content of the non-conjugated olefin unit is within the above range, a high-strength copolymer can be obtained, the shape retention when the resin molded product is stretched is good, and the shape recovery after heating is improved. To do.

(Aromatic vinyl unit)
The aromatic vinyl unit is a structural unit derived from an aromatic vinyl compound as a monomer.
By containing the aromatic vinyl unit in the copolymer, excessive crystallization derived from the non-conjugated olefin unit can be suppressed, and the rigidity of the resin molded product can be improved while the elasticity can be less likely to be impaired.
Here, the aromatic vinyl compound refers to an aromatic compound substituted with at least a vinyl group, and is not included in the conjugated diene compound. The aromatic vinyl compound preferably has 8 to 10 carbon atoms. Examples of such aromatic vinyl compounds include styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, o, p-dimethylstyrene, o-ethylstyrene, m-ethylstyrene, p-ethylstyrene and the like. .. The aromatic vinyl compound may be one kind alone or a combination of two or more kinds.

The aromatic vinyl compound as the monomer of the copolymer provides a high-strength copolymer, which improves the shape retention of the resin molded product during stretching and improves the shape recovery after heating. From the viewpoint, it is preferable to contain styrene, and it is more preferable to contain only styrene. In other words, the aromatic vinyl unit in the copolymer preferably contains styrene units, and more preferably consists of only styrene units.
The aromatic ring in the aromatic vinyl unit is not included in the main chain of the copolymer unless it is bonded to an adjacent unit.

The content of the aromatic vinyl unit of the copolymer is preferably 0.1 mol% or more, and more preferably 2 mol% or more. The content of the aromatic vinyl unit is preferably 50 mol% or less, more preferably 40 mol% or less, further preferably 30 mol% or less, and particularly preferably 20 mol% or less.

The number of types of monomers of the copolymer is particularly limited as long as the copolymer contains a conjugated diene unit, a non-conjugated olefin unit, and an aromatic vinyl unit and does not contain a butylene unit. There is no. The copolymer may have other structural units (excluding butylene units) other than the conjugated diene unit, the non-conjugated olefin unit, and the aromatic vinyl unit, but the content of the other structural units is From the viewpoint of obtaining a desired effect, it is preferably 30 mol% or less, more preferably 20 mol% or less, further preferably 10 mol% or less, and not contained, that is, the content of the total copolymer. Is particularly preferably 0 mol%.

The copolymer is a kind of monomer from the viewpoint of exhibiting high tensile strength, being able to maintain a good shape when it is made into a stretched resin molded product, and improving the recoverability of the shape by heating. It is preferably a polymer obtained by polymerizing only a conjugated diene compound, only one non-conjugated olefin compound, and at least one aromatic vinyl compound.
In other words, the copolymer is preferably a copolymer containing only one conjugated diene unit, only one non-conjugated olefin unit, and only one aromatic vinyl unit, preferably only one type of conjugated. More preferably, it is a ternary copolymer consisting of only a diene unit, only one non-conjugated olefin unit, and only one aromatic vinyl unit, and consists of only 1,3-butadiene units, ethylene units, and styrene units. It is more preferably a ternary copolymer. Here, "only one type of conjugated diene unit" includes conjugated diene units having different binding modes.

The copolymer has a conjugated diene unit content of 2 to 90 mol%, a non-conjugated olefin unit content of 2 to 98 mol%, and an aromatic vinyl unit content of 0.1 to 50 mol%. It is preferable to have.

The weight average molecular weight (Mw) of the copolymer in terms of polystyrene is preferably 100,000 to 1,000,000, more preferably 300,000 to 650,000, and 350,000 to 600,000. Is more preferable, and 370,000 to 550,000 is particularly preferable. When the Mw of the copolymer is 100,000 or more, good processability can be ensured, and when the Mw is 1,000,000 or less, the workability of the resin composition is not easily impaired. ..

The copolymer preferably has a polystyrene-equivalent number average molecular weight (Mn) of 50,000 to 800,000, more preferably 100,000 to 500,000, and 120,000 to 400,000. It is more preferable to have. When the Mn of the copolymer is 50,000 or more, the processability can be improved. Further, when Mn is 800,000 or less, the workability of the resin composition is not easily impaired.

The copolymer has a molecular weight distribution [Mw / Mn (weight average molecular weight / number average molecular weight)] of preferably 1.80 to 4.00, more preferably 2.00 to 3.70, and 2 It is more preferably .20 to 3.50. When the molecular weight distribution of the copolymer is 4.00 or less, sufficient homogeneity can be brought about in the physical properties of the copolymer.

The weight average molecular weight (Mw), number average molecular weight (Mn), and molecular weight distribution (Mw / Mn) of the copolymer are determined by gel permeation chromatography (GPC) using polystyrene as a standard substance.

It is preferable that the main chain of the copolymer has only an acyclic structure. As a result, it becomes easy to maintain the shape by stretching the resin molded product, and further, the recoverability of the shape after heating can be improved.
In addition, NMR is used as a main measuring means for confirming whether or not the main chain of the copolymer has a cyclic structure. Specifically, when a peak derived from the cyclic structure existing in the main chain (for example, a peak appearing at 10 to 24 ppm for a three-membered ring to a five-membered ring) is not observed, the main chain of the copolymer is determined. It is shown that it consists only of a non-cyclic structure.
In the present invention, the main chain of the polymer means a linear molecular chain in which all other molecular chains (long molecular chain, short molecular chain, or both) are connected like a pendant ["". See section 1.34 of Glossary of Basic Terms in Polymer Science IUPAC Recommendations 1996, Pure Appl. Chem., 68, 2287-2311 (1996)]
Further, the non-cyclic structure means a linear structure or a branched structure.

The copolymer preferably has a melting point. When the copolymer has a melting point, the melting point is preferably 30 ° C. or higher, more preferably 40 ° C. or higher. When the copolymer has a plurality of melting points, the highest melting point is preferably 30 ° C. or higher, more preferably 40 ° C. or higher. The upper limit of the melting point of the copolymer is not particularly limited, but from the viewpoint of processability, it is preferably 120 ° C. or lower, and preferably 110 ° C. or lower.

The copolymer is preferably excellent in tensile strength. Specifically, the copolymer preferably has a tensile strength of 3 MPa or more, more preferably 5 MPa or more, and even more preferably 10 MPa or more. For the tensile strength, a test piece for tensile test (test piece type 1B size described in JIS K 7127: 1999) is collected from the resin molded body, and the test piece is subjected to a tensile tester at a speed of 100 mm / min. When the test piece was pulled and the test piece broke, the measurement was interrupted, and the stress at that time was taken as the tensile strength.

The copolymer preferably has a crystalline component derived from a non-conjugated olefin unit. By having a crystal component derived from a non-conjugated olefin unit, it is possible to obtain a resin molded product having excellent fracture strength.

The copolymer can be produced through a polymerization step using a conjugated diene compound, a non-conjugated olefin compound, and an aromatic vinyl compound as a monomer, and if necessary, a coupling step, a washing step, and other steps. It may go through a process.
Here, in the production of the copolymer, it is preferable that only the non-conjugated olefin compound and the aromatic vinyl compound are added without adding the conjugated diene compound in the presence of the polymerization catalyst, and these are first polymerized. In particular, when the catalyst composition described below is used, the conjugated diene compound is more reactive than the non-conjugated olefin compound and the aromatic vinyl compound. Therefore, the non-conjugated olefin compound and the aromatic compound are present in the presence of the conjugated diene compound. It is difficult to polymerize either or both of the group vinyl compounds. Further, it is also liable to be difficult due to the characteristics of the catalyst to first polymerize the conjugated diene compound and then additionally polymerize the non-conjugated olefin compound and the aromatic vinyl compound.

As the polymerization method, any method such as a solution polymerization method, a suspension polymerization method, a liquid phase massive polymerization method, an emulsion polymerization method, a vapor phase polymerization method, and a solid phase polymerization method can be used. When a solvent is used in the polymerization reaction, the solvent may be any solvent inactive in the polymerization reaction, and examples thereof include toluene, cyclohexane, and normal hexane.

The polymerization step may be carried out in one step or in multiple steps of two or more steps.
The one-step polymerization step is all kinds of monomers to be polymerized, namely conjugated diene compounds, non-conjugated olefin compounds, aromatic vinyl compounds, and other monomers, preferably conjugated diene compounds, non-conjugated. This is a step of polymerizing an olefin compound and an aromatic vinyl compound by reacting them all at once.
In the multi-step polymerization step, a part or all of one or two kinds of monomers are first reacted to form a polymer (first polymerization step), and then added in the first polymerization step. It is a step of polymerizing by performing one or more steps (second polymerization step to final polymerization step) of adding and polymerizing the type of monomer that was not used, the remainder of the monomer added in the first polymerization step, and the like. .. In particular, in the production of a copolymer, it is preferable to carry out the polymerization step in multiple stages.

In the polymerization step, the polymerization reaction is preferably carried out in an atmosphere of an inert gas, preferably nitrogen gas or argon gas. The polymerization temperature of the polymerization reaction is not particularly limited, but is preferably in the range of -100 ° C to 200 ° C, and may be about room temperature. The pressure of the polymerization reaction is preferably in the range of 0.1 to 10.0 MPa in order to sufficiently incorporate the conjugated diene compound into the polymerization reaction system.
The reaction time of the polymerization reaction is also not particularly limited, and is preferably in the range of 1 second to 10 days, but can be appropriately selected depending on conditions such as the type of polymerization catalyst and the polymerization temperature.
Further, in the polymerization step of the conjugated diene compound, the polymerization may be stopped by using a polymerization terminator such as methanol, ethanol or isopropanol.

The polymerization step is preferably carried out in multiple steps. More preferably, the first step of mixing the first monomer raw material containing at least an aromatic vinyl compound with the polymerization catalyst to obtain a polymerization mixture, and the conjugated diene compound, the non-conjugated olefin compound and the polymerization mixture with respect to the polymerization mixture. It is preferable to carry out the second step of introducing the second monomer raw material containing at least one selected from the group consisting of aromatic vinyl compounds. Further, it is more preferable that the first monomer raw material does not contain the conjugated diene compound and the second monomer raw material contains the conjugated diene compound.

The first monomer raw material used in the first step may contain a non-conjugated olefin compound together with the aromatic vinyl compound. In addition, the first monomer raw material may contain the entire amount of the aromatic vinyl compound used, or may contain only a part of the aromatic vinyl compound. Further, the non-conjugated olefin compound is contained in at least one of the first monomer raw material and the second monomer raw material.

The first step is preferably carried out in the reactor in an atmosphere of an inert gas, preferably nitrogen gas or argon gas. The temperature (reaction temperature) in the first step is not particularly limited, but is preferably in the range of -100 ° C to 200 ° C, and may be about room temperature. The pressure in the first step is not particularly limited, but is preferably in the range of 0.1 to 10.0 MPa in order to sufficiently incorporate the aromatic vinyl compound into the polymerization reaction system. The time (reaction time) spent in the first step can be appropriately selected depending on the conditions such as the type of polymerization catalyst and the reaction temperature. For example, when the reaction temperature is 25 to 80 ° C., it is 5 minutes. The range of ~ 500 minutes is preferable.

In the first step, as the polymerization method for obtaining the polymerization mixture, any method such as a solution polymerization method, a suspension polymerization method, a liquid phase massive polymerization method, an emulsion polymerization method, a gas phase polymerization method, and a solid phase polymerization method can be used. Can be used. When a solvent is used in the polymerization reaction, the solvent may be any solvent inactive in the polymerization reaction, and examples thereof include toluene, cyclohexanone, and normal hexane.

The second monomer raw material used in the second step is only a conjugated diene compound, a conjugated diene compound and a non-conjugated olefin compound, a conjugated diene compound and an aromatic vinyl compound, or a conjugated diene compound and a non-conjugated olefin compound. And aromatic vinyl compounds are preferred.
When the second monomer raw material contains at least one selected from the group consisting of a non-conjugated olefin compound and an aromatic vinyl compound in addition to the conjugated diene compound, these monomer raw materials are used as a solvent or the like in advance. It may be introduced into the polymerization mixture after being mixed with, or each monomer raw material may be introduced from a single state. Further, each monomer raw material may be added at the same time or sequentially.
In the second step, the method of introducing the second monomer raw material into the polymerization mixture is not particularly limited, but the flow rate of each monomer raw material is controlled and continuously added to the polymerization mixture. It is preferable to do (so-called monomering). Here, when a monomer raw material that is a gas under the conditions of the polymerization reaction system (for example, ethylene as a non-conjugated olefin compound under the conditions of room temperature and normal pressure) is used, the polymerization reaction system is carried out at a predetermined pressure. Can be introduced in.

The second step is preferably carried out in the reactor in an atmosphere of an inert gas, preferably nitrogen gas or argon gas. The temperature (reaction temperature) in the second step is not particularly limited, but is preferably in the range of -100 ° C to 200 ° C, and may be about room temperature. When the reaction temperature is raised, the selectivity of cis-1,4 bond in the conjugated diene unit may decrease. The pressure in the second step is not particularly limited, but is preferably in the range of 0.1 to 10.0 MPa in order to sufficiently incorporate a monomer such as a conjugated diene compound into the polymerization reaction system. The time (reaction time) spent in the second step can be appropriately selected depending on the conditions such as the type of polymerization catalyst and the reaction temperature, but is preferably in the range of 0.1 hour to 10 days, for example.
Further, in the second step, the polymerization reaction may be stopped by using a polymerization terminator such as methanol, ethanol or isopropanol.

Here, in the polymerization step of the above-mentioned conjugated diene compound, non-conjugated olefin compound, and aromatic vinyl compound, various monomers are used as catalyst components in the presence of one or more of the following components (A) to (F). It is preferable to include a step of polymerizing. In the polymerization step, it is preferable to use one or more of the following components (A) to (F), but it is possible to combine two or more of the following components (A) to (F) and use them as a catalyst composition. More preferred.
(A) Component: Rare earth element compound or reaction product of the rare earth element compound and Lewis base (B) Component: Organic metal compound (C) Component: Aluminoxane (D) Component: Ionic compound (E) Component: Halogen compound ( F) Ingredients: substituted or unsubstituted cyclopentadiene (compound having a cyclopentadiene group), substituted or unsubstituted indene (compound having an indenyl group), and substituted or unsubstituted fluorene (compound having a fluorenyl group). ), The cyclopentadiene skeleton-containing compound (A) to (F) can be used in the polymerization step by referring to, for example, International Publication No. 2018/092733.

The coupling step is a step of carrying out a reaction (coupling reaction) for modifying at least a part (for example, a terminal) of the polymer chain of the copolymer obtained in the polymerization step.
In the coupling step, it is preferable to carry out the coupling reaction when the polymerization reaction reaches 100%.
The coupling agent used in the coupling reaction is not particularly limited and may be appropriately selected depending on the intended purpose. For example, a tin-containing compound such as bis (-1-octadecyl maleate) dioctyltin (IV); 4 , 4'-Isocyanate compounds such as diphenylmethane diisocyanate; alkoxysilane compounds such as glycidylpropyltrimethoxysilane, and the like. These may be used alone or in combination of two or more.
Among these, bis (-1-octadecyl maleate) dioctyltin (IV) is preferable in terms of reaction efficiency and low gel formation.
The number average molecular weight (Mn) of the copolymer can be increased by carrying out the coupling reaction.

The washing step is a step of washing the copolymer obtained in the polymerization step.
The medium used for cleaning is not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof include methanol, ethanol and isopropanol. When a catalyst derived from sulfuric acid is used as the polymerization catalyst. Can be used by adding an acid (for example, hydrochloric acid, sulfuric acid, nitric acid, etc.) to these solvents. The amount of acid to be added is preferably 15 mol% or less with respect to the solvent. When the addition amount is 15 mol% or less, the acid is less likely to remain in the copolymer and is less likely to adversely affect the reaction during kneading and vulcanization of the resin composition.
By this washing step, the amount of catalyst residue in the copolymer can be suitably reduced.

[Other ingredients]
The resin composition of the present invention contains other resins in addition to the above-mentioned copolymer as long as the shape is maintained in the stretched state and the shape is restored to the shape before stretching after heating. You can go out. For example, the resin composition of the present invention further comprises a polypropylene resin, a polyamide resin, a polyphenylene ether resin, a polyphenylene sulfide resin, an acrylonitrile-butadiene-styrene copolymer resin, a polyethylene resin, a polyethylene terephthalate resin, and a polybutylene in addition to the above copolymer. It can contain a terephthalate resin, a polycarbonate resin, a polycaprolactone resin, and a polystyrene resin.

The polypropylene-based resin means a polymer containing a propylene unit as a main component (for example, more than 50 mol%) in the main chain, and may further contain other units such as an ethylene unit. Further, the polypropylene-based resin may be thermosetting or thermoplastic. Examples thereof include polypropylene (homogeneous polymer) and ethylene-propylene copolymer.
The polypropylene-based resin preferably has a polystyrene-equivalent number average molecular weight (Mn) of 5,000 to 10,000,000, more preferably 7,000 to 1,000,000. It is more preferably ~ 1,000,000.

As the polypropylene-based resin as described above, for example, commercially available Prime PP (registered trademark) manufactured by Prime Polymer Co., Ltd., Novatec PP (registered trademark) manufactured by Nippon Polypropylene Co., Ltd., Wintech (registered trademark) and the like can be used. it can.

The polystyrene-equivalent number average molecular weight (Mn) of the polyamide resin is preferably 5,000 to 10,000,000, more preferably 7,000 to 1,000,000. It is more preferably ~ 1,000,000.

As the above-mentioned polyamide-based resin, for example, commercially available UBE nylon 1022B, UBESTA1024U, etc. manufactured by Ube Industries, Ltd. can be used.

The content of the copolymer in the resin composition has the property that the stretched state is maintained to some extent when the resin molded product is stretched, and that the shape before stretching is satisfactorily restored after heating at 35 ° C. or higher. The present invention is not particularly limited as long as it satisfies the above requirements that the above-mentioned copolymer can be compatible with other resins. That is, the content of the copolymer in the resin composition can be appropriately set according to the type of other resin to be mixed. For example, when the above-mentioned copolymer and polypropylene-based resin are mixed, the content of the copolymer is preferably 20% by mass or more, more preferably 23% by mass or more, and 27% by mass. More preferably, it is more preferably 80% by mass or less, more preferably 77% by mass or less, and further preferably 73% by mass or less.

[Other additives]
The resin composition of the present invention is a compounding agent usually used in the resin industry, for example, a cross-linking agent other than the copolymer in the present invention, an anti-aging agent, an ultraviolet absorber, a filler, a compatibilizer, a colorant and the like. May be appropriately selected and contained within a range that does not impair the object of the present invention.

[Manufacturing method of resin composition]
The resin composition is obtained by blending the copolymer of the present invention with other resins or additives as necessary, and using a Banbury mixer, a roll, an internal mixer, a single-screw extrusion kneader, a twin-screw extrusion kneader, or the like. It can be produced by kneading using a kneader.
It is preferable that each component to be blended in the production of the resin composition is blended in an amount indicated as the content of each component in the resin composition.
The kneading of each component may be carried out in one step or divided into two or more steps.

Hereinafter, the present invention will be described in more detail with reference to examples, but these examples are for the purpose of exemplifying the present invention and do not limit the present invention in any way.

[Method for producing copolymer]
52 g of styrene and 762 g of toluene were added to a fully dried 2000 mL pressure resistant stainless steel reactor.
In a glove box under a nitrogen atmosphere, a mono (bis (1,3-tert-butyldimethylsilyl) indenyl) bis (bis (dimethylsilyl) amide) gadolinium complex 1,3-[(t-Bu) is placed in a glass container. Me ₂ Si] ₂ C ₉ H ₅ Gd [N (SiHMe ₂ ) 2] 0.031 mmol, dimethylanilinium tetrakis (pentafluorophenyl) borate [Me ₂ NHPhB (C ₆ F ₅ ) ₄ ] 0.031 mmol was charged. 21 g of toluene was added to prepare a catalytic solution. The catalyst solution was added to the pressure resistant stainless steel reactor and heated to 60 ° C. In addition, "t-Bu" means a tert-butyl group, "Me" means a methyl group, and "Ph" means a phenyl group (the same in the synthesis method of polymers 2 and 3).
Next, ethylene was charged into the pressure-resistant stainless steel reactor at a pressure of 1.0 MPa, and copolymerization was carried out at 75 ° C. for a total of 9 hours. 1,3-Butadiene was continuously added at 0.6 mL / min. 108 g of a toluene solution containing 27 g of 1,3-butadiene was added at the rate of. ..
Then, 1 mL of a 5 mass% isopropanol solution of 2,2'-methylene-bis (4-ethyl-6-t-butylphenol) (NS-5) was added to the pressure resistant stainless steel reactor to terminate the reaction.
Then, the copolymer was separated using a large amount of methanol and vacuum dried at 50 ° C. to obtain a copolymer.

[Method for measuring physical properties of copolymer]
(1) Number average molecular weight (Mn), weight average molecular weight (Mw), peak top molecular weight (Mp) and molecular weight distribution (Mw / Mn)
Gel permeation chromatography [GPC: HLC-8121 GPC / HT manufactured by Toso Co., Ltd., column: GMH _HR- H (S) HT x 2, manufactured by Toso Co., Ltd., detector: differential refractometer (RI)] to obtain monodisperse polystyrene. As a reference, the polystyrene-equivalent number average molecular weight (Mn), weight average molecular weight (Mw), peak top molecular weight (Mp), and molecular weight distribution (Mw / Mn) of the copolymer were determined. The measurement temperature is 40 ° C. The results are shown in Table 1.

(2) Content of ethylene unit, butadiene unit, styrene unit, butylene unit The content (mol%) of ethylene unit, butadiene unit, styrene unit, and butylene unit in the copolymer is determined by ¹ H-NMR spectrum (100 ° C.). , D-Tetrachloroethane standard: 6 ppm) was determined from the integration ratio of each peak. The results are shown in Table 1.
The total content of each of the ethylene unit, the butadiene unit, and the styrene unit of the synthesized copolymer was 100 mol%, and the content of the butylene unit was 0 mol%.

(3) Melting Point The melting point of the copolymer was measured according to JIS K 7121: 1987 using a differential scanning calorimeter (DSC, manufactured by TA Instruments Japan, "DSCQ2000"). The results are shown in Table 1.

(4) Confirmation of main chain structure ¹³ C-NMR spectrum was measured for the synthesized copolymer.
Since no peak was observed at 10 to 24 ppm in the ¹³ C-NMR spectrum chart of the synthesized copolymer, it was confirmed that the main chain of the synthesized copolymer consisted only of acyclic structure.

[Manufacturing of resin molded products]
The synthesized copolymer (Example 1), polyethylene resin (Comparative Example 1), and hydrogenated styrene-based thermoplastic elastomer (SEBS, Comparative Example 2) are individually melt-kneaded and kneaded using a mold having a thickness of 2 mm. The resin molded products of Example 1 and Comparative Examples 1 and 2 were obtained by pressing at 150 ° C. for 5 minutes.
The following polyethylene resin and SEBS were used.
(1) Polyethylene resin (PE resin): Made by Ube-Maruzen Polyethylene Co., Ltd., trade name "Umerit (registered trademark) 1540F"
(2) Hydrogenated styrene-based thermoplastic elastomer (SEBS): manufactured by Asahi Kasei Corporation, trade name "Tough Tech (registered trademark) H1062"

[Tensile strength evaluation]
A test piece for tensile test (JIS K 7127: 1999 test piece type 1B size) was collected from the resin molded products of Example 1 and Comparative Examples 1 and 2.
The test piece was pulled at a speed of 100 mm / min with a tensile tester, the measurement was interrupted when the test piece broke, and the stress at that time was taken as the tensile strength. The results are shown in Table 2.

[Evaluation of shape recovery]
From the resin molded products of Example 1 and Comparative Examples 1 and 2, JIS-7 dumbbell-shaped test pieces were produced by punching.
FIG. 1 shows a schematic diagram of the test piece used for the shape recovery evaluation.
The test piece 10 shown in FIG. 1 has a JIS-7 dumbbell shape in which both ends of the shaft portion 12 are bulged. The test piece 10 was provided with a total of four reference points, 14b, 14a, 14a (second), and 14b (second), in a straight line in the major axis direction of the shaft portion 12. The reference point 14a and the reference point 14a (second); the reference point 14b and the reference point 14b (second) are respectively placed at positions symmetrical with respect to the center of the shaft portion 12.
The distance between the reference points 14a was set to 5 mm. That is, the two reference points 14a are separated from the center of the shaft portion 12 by 2.5 mm.
The two outer points (marking point 14b) were attached to the outside by 0.5 mm from each of the two inner points (marking point 14a). That is, the two reference points 14b are separated from the center of the shaft portion 12 by 3.0 mm.

Then, each test piece was stretched by a tensile tester (manufactured by Shimadzu Corporation, Autograph AG-X, a precision universal testing machine) until a stress of 20 MPa was generated. If the test piece broke, stretching was stopped at that point. The distance between the two inner gauge points (14a) was measured for the test piece before stretching.
The tensile setting conditions for the resin molded product using the tensile test device are as follows.
Maximum load cell stress: 5 kN
Displacement measurement: Displacement is measured by the distance between the two outer gauge points (14b) Chuck shape and tightening pressure: Tightening with a pressure of 0.5 MPa sandwiched between two plates Tensile speed: 100 mm / min
Atmospheric temperature: Room temperature (25 ° C)

The test piece in a creeped state after stretching was immersed in a water bath at 80 ° C. for 10 seconds to warm it. After heating, the distance between the two inner gauge points (14a) was measured.
The ratio of the distance between the reference points 14a before stretching and the distance between the reference points 14a after heating (the following formula (1)) was calculated and used as the shape recovery rate. Further, the shape recovery index of Examples and each Comparative Example was calculated by the formula (2) based on the shape recovery rate of Comparative Example 1.
Shape recovery rate = (distance between gauge points 14a after heating) / (distance between gauge points 14a before stretching) ... (1)
Shape recovery index = (shape recovery rate of Comparative Example 1) / (shape recovery rate of Example or Comparative Example) × 100 ... (2)
The results are shown in Table 2. The larger the index value, the more the resin molded product has returned to a length close to the initial length.

It was obtained that the resin molded product of Example 1 (the resin molded product made of the copolymer in the present invention) maintained its shape during stretching and was excellent in shape recovery by heating.
On the other hand, the resin molded product (polyethylene resin) of Comparative Example 1 was a resin having a higher tensile strength than that of Example 1, but the shape did not change even after heating and remained in a stretched state. Therefore, the shape recovery index was 100.
The resin molded product (SEBS) of Comparative Example 2 was broken at 3.1 MPa at the time of deformation, so that the shape recovery property could not be evaluated.
As described above, it has been proved that the resin molded product made of the copolymer in the present invention has a property that the shape is maintained by stretching but the shape is restored by heating.

10 Test piece 12 Shafts 14a, 14b Reference points

Claims (4)

A method for recovering the shape of a resin molded product in a stretched state by heating the resin molded product to 35 ° C. or higher and 150 ° C. or lower to return the resin molded product to the state before stretching.
The resin molded product is a resin molded product comprising a copolymer containing a conjugated diene unit, a non-conjugated olefin unit, and an aromatic vinyl unit and having a butylene unit content of 0 mol%. Shape recovery method. The copolymer has a conjugated diene unit content of 2 to 90 mol%, a non-conjugated olefin unit content of 2 to 98 mol%, and an aromatic vinyl unit content of 0.1 to 1. The method for recovering the shape of a resin molded product according to claim 1, which is 50 mol%. The method for recovering the shape of a resin molded product according to claim 1 or 2, wherein the resin molded product is stretched to a stress of 4 MPa or more and 60 MPa or less and then heated. The method for recovering the shape of a resin molded product according to claim 1 or 2, wherein the resin molded product having a draw ratio of 300% or more and 700% or less is heated.