JP2022093294A - Resin composition, sheet for mouth guard, and mouth guard - Google Patents

Abstract

To provide a sheet for mouth guards that has excellent separability in separation from a gypsum mold or the like after the production of a molding, and also has excellent chewability when bitten, and a resin composition that can be used in the production of a mouth guard.SOLUTION: A resin composition has a peak value of loss tangent (tanδ) of 0.40-1.27 by dynamic viscoelasticity measurement at 10 rad/s in frequency, the temperature of the peak value being 22°C or higher.SELECTED DRAWING: None

Description

The present disclosure relates to resin compositions, mouthguard sheets, and mouthguards.

In sports with intense movements such as boxing, rugby, and American football, protection commonly called a mouthguard (also called a mouthpiece) to protect the dentition and oral soft tissue and to reduce the impact on the brain. The ingredients are widely used.

Conventionally, mouthguards made of ethylene-vinyl acetate copolymer (EVA) have been known, but various mouthguards have problems such as low impact absorption and easy breakage due to the application of quotient force. Has been developed.

For example, in Patent Document 1, a composition containing a 4-methyl-1-pentene-propylene copolymer composed of a structural unit derived from 4-methyl-1-pentene and a thermoplastic resin is shock-absorbent. It is disclosed that it can be used for manufacturing a mouthguard sheet and a mouthguard (mainly a sports mouthguard) which are excellent in quality, thinner than conventional ones, lighter in weight, and comfortable to wear.

Japanese Unexamined Patent Publication No. 2012-40136

The mouth guard can be molded using a plaster mold or the like. At that time, the molded mouthguard is peeled off from a plaster mold or the like to separate it.
The mouthguard sheet and mouthguard of Patent Document 1 may require an excessive force to be separated from a plaster mold or the like after being molded.
Further, even when the separation from the plaster mold or the like does not require an excessive force, the rebound resilience when the mouth guard is bitten is high, so that the biting comfort may be deteriorated.

The problem to be solved by one embodiment of the present disclosure is a mouthguard sheet and a mouthguard which are excellent in separability when separated from a plaster mold or the like after manufacturing a molded product and have good chewing comfort when chewed. It is an object of the present invention to provide a resin composition that can be used for producing the above-mentioned resin composition, a mouthguard sheet made of a molded product of the above-mentioned resin composition, and a mouthguard including the above-mentioned mouthguard sheet.

The means for solving the above problems include the following embodiments.
<1> A resin composition having a peak value of loss tangent (tan δ) measured by dynamic viscoelasticity measurement at a frequency of 10 rad / s of 0.40 to 1.27 and a temperature of the peak value of 22 ° C. or higher.
<2> The resin composition according to <1>, which has a shore A hardness of 75 or less at 37 ° C.
<3> A structural unit (i) derived from 15 mol% to 80 mol% 4-methyl-1-pentene and a structural unit (ii) derived from 20 mol% to 85 mol% propylene (however, the above-mentioned structural unit). The total of the ratio of (i) and the ratio of the structural unit (ii) is 100 mol%), and the 4-methyl-1-pentene-propylene copolymer (A) and the 4-methyl-1. -The resin composition according to <1> or <2>, which comprises at least one polymer (B) selected from the group consisting of a thermoplastic resin other than the penten-propylene copolymer (A) and rubber. ..
<4> The polymer (B) is isotactic polypropylene, poly 1-butene, poly 4-methyl-1-pentene, ethylene / α-olefin copolymer, propylene / α-olefin copolymer and 1-. The resin composition according to <3>, which is at least one selected from the group consisting of a butene / α-olefin copolymer.
<5> The polymer (B) is at least one selected from the group consisting of an ethylene / α-olefin copolymer, a propylene / α-olefin copolymer and a 1-butene / α-olefin copolymer. The resin composition according to <3> or <4>.
<6> 30 parts by mass to 70 parts by mass of the 4-methyl-1-pentene / propylene copolymer (A) and 70 parts by mass to 30 parts by mass (however, both 4-methyl-1-pentene / propylene). The total amount of the polymer (A) and the polymer (B) is 100 parts by mass.) Described in any one of <3> to <5> containing the polymer (B). Resin composition <7> The resin composition according to any one of <1> to <6>, which is a resin composition for mouse guard.
<8> A mouthguard sheet made of a molded product of the resin composition according to any one of <1> to <7>.
<9> A mouth guard including the mouth guard sheet according to <8>.

According to one embodiment of the present disclosure, it is used for manufacturing a mouthguard sheet and a mouthguard which are excellent in separability when separated from a plaster mold or the like after manufacturing a molded product and have good chewing comfort when chewed. It is possible to provide a mouthguard including a resin composition that can be produced, a mouthguard sheet made of a molded product of the resin composition, and a mouthguard sheet.

In the present disclosure, the numerical range represented by using "-" means a range including the numerical values before and after "-" as the lower limit value and the upper limit value.
In the present disclosure, the amount of each component contained in the composition is the total amount of the plurality of substances present in the composition unless otherwise specified, when a plurality of substances corresponding to each component are present in the composition. Means.
In the numerical range described stepwise in the present disclosure, the upper limit value or the lower limit value described in one numerical range may be replaced with the upper limit value or the lower limit value of the numerical range described in another stepwise description. .. Further, in the numerical range described in the present disclosure, the upper limit value or the lower limit value of the numerical range may be replaced with the value shown in the examples.

≪Resin composition≫
In the resin composition of the present disclosure, the peak value of loss tangent (tan δ) by dynamic viscoelasticity measurement at a frequency of 10 rad / s is 0.40 to 1.27, and the temperature of the peak value is 22 ° C. or higher.
In the present disclosure, the "peak value of loss tangent (tan δ) by dynamic viscoelasticity measurement at a frequency of 10 rad / s" may be simply referred to as "peak value".

By including the above-mentioned constitution, the resin composition of the present disclosure has excellent separability when separated from a gypsum mold or the like after manufacturing a molded product, and a mouthguard sheet having good chewing comfort when chewed. Mouthguards can be manufactured.

<Peak value>
The peak value is preferably 1.20 or less, preferably 1.10 or less, and particularly preferably 1.05 or less, from the viewpoint of improving the separability at the time of molding.
On the other hand, from the viewpoint of improving the chewing comfort by improving the elastic modulus, 0.50 or more is preferable, 0.60 or more is more preferable, and 0.70 or more is particularly preferable.

The peak value in the present disclosure can be reduced, for example, by reducing the content of the copolymer (A) described later or increasing the content of the polymer (B) described later.
Further, the peak value can be increased by increasing the content of the copolymer (A) described later or decreasing the content of the polymer (B) described later.
Further, when the polymer (B) is a propylene / α-olefin copolymer, the peak value of Tan δ can be made larger.

<Peak temperature>
The temperature of the peak value is preferably 23 ° C. or higher, more preferably 24 ° C. or higher, still more preferably 25 ° C. or higher, from the viewpoint of improving separability during molding.
On the other hand, the temperature of the peak value is preferably 40 ° C. or lower, more preferably 35 ° C. or lower, still more preferably 30 ° C. or lower, from the viewpoint of operability.

The temperature of the peak value in the present disclosure can be lowered, for example, by reducing the composition ratio of 4-methyl-1-pentene of the copolymer (A) described later.

The method of measuring the peak value and the temperature of the peak value in the present disclosure is as described in Examples described later.

There is no particular limitation as a method for adjusting the above-mentioned peak value and the temperature of the above-mentioned peak value within the above-mentioned range.
For example, the resin compositions of the present disclosure are composed of a structural unit (i) derived from 15 mol% to 80 mol% 4-methyl-1-pentene and a structural unit (ii) derived from 20 mol% to 85 mol% propylene. ) (However, the total of the proportion of the constituent unit (i) and the proportion of the constituent unit (ii) is 100 mol%.) Together with the 4-methyl-1-pentene-propylene copolymer (A). It may contain at least one polymer (B) selected from the group consisting of a thermoplastic resin other than the polymer (A) and rubber.
By containing the above-mentioned constitution, the resin composition of the present disclosure facilitates adjusting the above-mentioned peak value and the temperature of the above-mentioned peak value within the above-mentioned range.

(4-Methyl-1-pentene-propylene copolymer (A))
The 4-methyl-1-pentene-propylene copolymer (A) (also simply referred to as the copolymer (A) in the present disclosure) is derived from 15 mol% to 80 mol% of 4-methyl-1-pentene. The derived structural unit (i) and the structural unit (ii) derived from 25 mol% to 85 mol% propylene (however, the total of the ratio of the structural unit (i) and the ratio of the structural unit (ii) is 100 mol. %.).

The proportion of the structural unit (i) derived from 4-methyl-1-pentene is preferably 40 mol% to 75 mol%, more preferably 50 mol% to 75 mol%, still more preferably 65 mol%. It is ~ 75 mol%.
The proportion of the structural unit (ii) derived from propylene is preferably 25 mol% to 60 mol%, more preferably 25 mol% to 50 mol%, still more preferably 25 mol% to 35 mol%. Is.

When the ratio of the structural unit (i) is 15 mol% or more, the impact absorption, flexibility, and lightness of the molded product can be improved.
When the ratio of the structural unit (i) is 80 mol% or less, the impact absorption and flexibility of the molded product can be improved.

The 4-methyl-1-pentene-propylene copolymer (A) is a structural unit derived from other monomers as long as it is in a small amount (for example, 10 mol% or less) that does not impair the object of the present disclosure. May include. As specific examples of other monomers, ethylene, 1-butene, 1-hexene, 1-octene and the like are preferable.

The ultimate viscosity [η] of the 4-methyl-1-pentene-propylene copolymer (A) in decalin at 135 ° C. is preferably 0.01 dL / g to 5.0 dL / g, more preferably 0. It is 0.05 dL / g to 4.0 dL / g, more preferably 0.1 dL / g to 3.0 dL / g, and particularly preferably 0.5 dL / g to 2.5 dL / g.
As will be described later, when hydrogen is used in combination during polymerization, the molecular weight can be controlled, and the ultimate viscosity [η] can be adjusted by freely obtaining from a low molecular weight body to a high molecular weight body.

The mass average molecular weight (Mw) of the 4-methyl-1-pentene-propylene copolymer (A) measured by gel permeation chromatography (GPC) is preferably 500 to 10,000 in terms of polystyrene. It is 000, more preferably 1,000 to 5,000,000, and even more preferably 1,000 to 2,500,000.

The ratio (molecular weight distribution) of the 4-methyl-1-pentene-propylene copolymer (A) to the mass average molecular weight (Mw) and the number average molecular weight (Mn) measured by gel permeation chromatography (GPC). Mw / Mn) is preferably 1.0 to 3.5, more preferably 1.2 to 3.0, and even more preferably 1.5 to 2.5.

The copolymer (A) having a value of Mw / Mn within the above range is advantageous in producing a molded product having excellent mechanical properties and wear resistance with excellent moldability, and has an industrial value. Is higher.
By using a catalyst described later, it is possible to obtain the copolymer (A) having a Mw / Mn value within the above range within the range of the above-mentioned ultimate viscosity [η] or mass average molecular weight (Mw). can.
The values of Mw / Mn and Mw are values measured by the method adopted in the examples described later.

The density of the 4-methyl-1-pentene-propylene copolymer (A) (measured by ASTM D 1505) is preferably 880 kg / m ³ to 810 kg / m ³ , more preferably 860 kg / m ³ to 820 kg /. It is m ³ , more preferably 855 kg / m ³ to 830 kg / m ³ .

The density can be changed by the comonomer composition ratio of the 4-methyl-1-pentene-propylene copolymer (A), and the copolymer (A) within the above range produces a lightweight molded product. It is advantageous on.

It is preferable that the melting point [Tm] of the 4-methyl-1-pentene-propylene copolymer (A) measured by a differential scanning calorimeter (DSC) is less than 110 ° C. or not recognized. The melting point can be changed by the comonomer composition ratio of the 4-methyl-1-pentene-propylene copolymer (A), and the copolymer (A) within the above range is flexible and can be separated at the time of molding. It is advantageous in producing a molded product having high properties.

The 4-methyl-1-pentene-propylene copolymer (A) has a peak value of tangent tan δ obtained by dynamic viscoelasticity measurement at a frequency of 10 rad / s in a temperature range of -40 ° C to 180 ° C. However, it is preferably 0.1 to 10, more preferably 0.4 to 8.0, still more preferably 0.6 to 6.0, particularly preferably 1.5 to 5.0, and particularly preferably 2.0 to 2.0. It is 4.0.
Regarding the dynamic viscoelasticity measurement at a frequency of 10 rad / s, the details of the measurement conditions and the like are as described in the column of Examples described later.

Further, the temperature at which the value of tan δ becomes maximum (that is, the temperature of the peak value of tan δ) may be −40 ° C. to 180 ° C., preferably −40 ° C. to 100 ° C., more preferably −30. The temperature is in the range of ° C. to 50 ° C., more preferably −10 ° C. to 40 ° C., and particularly preferably 0 ° C. to 40 ° C. The peak value of tan δ can be controlled by the comonomer composition ratio of the 4-methyl-1-pentene / propylene copolymer (A), for example, the content of 4-methyl-1-pentene in the copolymer (A). By setting the content to 20 mol% to 72 mol%, it becomes easy to keep the peak value of tan δ within the above range.

The 4-methyl-1-pentene-propylene copolymer (A) has a rebound resilience (%) defined by the following formula of 0% to 25% at 40 ° C., which is a temperature condition assuming the oral cavity. It may be 0% to 20%, more preferably 0% to 10%.
Repulsive modulus (%) = (rebound height) (mm) / 460 x 100

The elastic modulus can be controlled by the comonomer composition ratio of the 4-methyl-1-pentene / propylene copolymer (A), for example, the 4-methyl-1-pentene content should be 20 mol% to 65 mol%. It becomes easy to keep the elastic modulus within the above range.

The method for producing the 4-methyl-1-pentene-propylene copolymer (A) is not particularly limited.
For example, the 4-methyl-1-pentene-propylene copolymer (A) can be produced by using the production method described in JP2012-40136A.

(Polymer (B))
The polymer (B) is at least one selected from the group consisting of a thermoplastic resin other than the copolymer (A) and rubber.
The polymer (B) is not particularly limited, and examples thereof include the following thermoplastic resins and rubbers.

Examples of the thermoplastic resin include a thermoplastic polyolefin resin (excluding the copolymer (A)), a thermoplastic polyester resin, a thermoplastic vinyl aromatic resin, a thermoplastic polyurethane, an ionomer, a fluororesin, and a rosin resin. , Terpen resin, petroleum resin and the like, and thermoplastic polyolefin resin and thermoplastic vinyl aromatic resin are preferable.

Specific examples of the thermoplastic polyolefin resin (excluding the copolymer (A)) include low-density, medium-density, high-density polyethylene, high-pressure low-density polyethylene, isotactic polypropylene, and syndiotactic polypropylene. , Poly1-butene, poly4-methyl-1-pentene, poly3-methyl-1-butene, ethylene / α-olefin copolymer, propylene / α-olefin copolymer, 1-butene / α-olefin Examples thereof include polymers, ethylene / vinyl acetate copolymers, ethylene / methacrylate acrylate copolymers, cyclic olefin copolymers, and chlorinated polyolefins.
Among these, low density, medium density, high density polyethylene, high pressure method low density polyethylene, isotactic polypropylene, syndiotactic polypropylene, poly 1-butene, poly 4-methyl-1-pentene, poly 3-methyl-1 -Buten, ethylene / α-olefin copolymer, propylene / α-olefin copolymer, and 1-butene / α-olefin copolymer, ethylene / vinyl acetate copolymer, and ethylene / methacrylate acrylate copolymer. Is preferable.

Specific examples of the thermoplastic vinyl aromatic resin include polystyrene, ABS resin, AS resin, and styrene-based elastomer (styrene / butadiene / styrene block polymer, styrene / isoprene / styrene block polymer, styrene / isobutylene / styrene block polymer). , These hydrogen additives, etc.) and the like.
Among these, polystyrene and styrene-based elastomers are preferable.

Examples of the rubber include copolymer rubber.
Specific examples of the rubber include ethylene / α-olefin / diene copolymer, propylene / α-olefin / diene copolymer, 1-butene / α-olefin / diene copolymer, polybutadiene rubber, and polyisobutylene rubber. , Neoprene rubber, nitrile rubber, butyl rubber, polyisobutylene rubber, natural rubber, silicone rubber and the like.
Among these, ethylene / α-olefin / diene copolymer, propylene / α-olefin / diene copolymer, 1-butene / α-olefin / diene copolymer, polybutadiene rubber, polyisobutylene rubber, neoprene rubber, nitrile. Rubber, butyl rubber, polyisobutylene rubber, and silicone rubber are preferred.

Among these, the polymer (B) is isotactic polypropylene, poly 1-butene, poly 4-methyl-1-pentene, ethylene / α-olefin copolymer, propylene / α-olefin copolymer and 1-. It is preferably at least one selected from the group consisting of butene / α-olefin copolymers.
The polymer (B) is more than one selected from the group consisting of an ethylene / α-olefin copolymer, a propylene / α-olefin copolymer and a 1-butene / α-olefin copolymer. preferable.

In addition, when a transparent color is required for the color of the mouthpiece determined by the sports competition, an isotactic polypropylene, poly1-butene, poly4-methyl-1-pentene, or an ethylene / α-olefin copolymer (for example). , Toughmer manufactured by Mitsui Chemicals, Inc.), propylene / α-olefin copolymer (for example, Vistamaxx manufactured by Exxon Mobile Co., Ltd.), 1-butene / α-olefin copolymer is more preferable, and ethylene / α-olefin copolymer weight is more preferable. Combines, propylene / α-olefin copolymers, and 1-butene / α-olefin copolymers are particularly preferred, and propylene / α-olefin copolymers are even more preferred.

As the thermoplastic resin and rubber in the present disclosure, the thermoplastic resin and rubber described in JP-A-2012-40136 can be referred to.
The thermoplastic resin and rubber may be used alone or in combination of two or more.

(Other additives)
The resin composition of the present disclosure includes softeners, various weather-resistant stabilizers, heat-resistant stabilizers, antioxidants, ultraviolet absorbers, antistatic agents, anti-slip agents, and anti-blocking agents to the extent that the purposes of the present disclosure are not impaired. , Antifogging agents, nuclear agents, lubricants, pigments, dyes, antiaging agents, hydrochloric acid absorbers, inorganic or organic fillers, organic or inorganic foaming agents, cross-linking agents, co-cross-linking agents, cross-linking aids, pressure-sensitive agents. , Flame-retardant agent, mold release agent and other additives may be blended as needed.

Specific examples of the additive include a phenolic stabilizer, 2,6-di-t-butyl-p-cresol, and tetrakis [methylene-3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate. ] Methan, 4,4'-butylidenebis (6-t-butyl-m-cresol), tocopherols, ascorbic acid, dilaurylthiodipropionate, phosphate stabilizer, fatty acid monoglyceride, N, N- [bis- 2-Hydroxyethyl] alkylamine, 2- (2'-hydroxy-3', 5'-di-t-butylphenyl) -5-chlorobenzotriazole, calcium stearate, magnesium oxide, magnesium hydroxide, alumina, hydroxylated Examples thereof include aluminum, silica, clay, gypsum, glass fiber, titania, calcium carbonate, carbon black and the like.

The resin composition of the present disclosure preferably contains 30 parts by mass to 70 parts by mass of the polymer (A) and 70 parts by mass to 30 parts by mass of the polymer (B), preferably 35 parts by mass. It is more preferable to contain the copolymer (A) of 65 parts by mass to 65 parts by mass and the polymer (B) of 65 parts by mass to 35 parts by mass.
In particular, when the polymer (B) is a propylene / α-olefin copolymer, the resin composition of the present disclosure contains 30 parts by mass to 70 parts by mass of the copolymer (A) and 70 parts by mass to 30 parts by mass. It is preferable to contain a part of the polymer (B).
When the polymer (B) is an ethylene / α-olefin copolymer, the resin composition of the present disclosure contains 40 parts by mass to 70 parts by mass of the copolymer (A) and 60 parts by mass to 30 parts by mass. It is preferable to contain a part of the polymer (B).
However, the total amount of the copolymer (A) and the polymer (B) is 100 parts by mass.

From the viewpoint of shock absorption of the molded product, flexibility at room temperature, and releasability from the molding mold, the lower limit of the copolymer (A) is preferably 35 parts by mass, more preferably 40 parts by mass. From the viewpoint of shock absorption, light weight, and good chewing comfort of the molded product, the upper limit of the copolymer (A) is preferably 65 parts by mass, more preferably 60 parts by mass.

The resin composition of the present disclosure can be prepared by mixing the 4-methyl-1-pentene-propylene copolymer (A) and the polymer (B), and optionally the additive. As a manufacturing method, a conventionally known mixing method, for example, a method of mixing with a plast mill, a Henschel mixer, a V-blender, a ribbon blender, a tumbler blender, a kneader luder, or the like, or after mixing, a single-screw extruder, a twin-screw extruder, or a kneader. , It can be manufactured by adopting a method of granulating or crushing after melt-kneading with a Banbury mixer or the like.

The resin composition of the present disclosure preferably has a shore A hardness of 75 or less, more preferably 70 or less, and even more preferably 65 or less in the molded product of the resin composition at 37 ° C.
The resin composition of the present disclosure preferably has a shore A hardness of 5 or more, more preferably 10 or more, and even more preferably 15 or more in the molded product of the resin composition at 37 ° C.
From the viewpoint of improving processability and chewing comfort, the resin composition of the present disclosure preferably has a shore A hardness of 99 or less, preferably 95 or less, in a molded product of the resin composition at room temperature (23 ° C.). More preferably, it is more preferably 90 or less.
From the viewpoint of improving the strength of the resin composition of the present disclosure, the shore A hardness at room temperature (23 ° C.) is preferably 60 or more, more preferably 65 or more in the molded product of the resin composition. , 70 or more is more preferable.
Details of the shore A hardness at 37 ° C. and room temperature (23 ° C.), such as measurement conditions, are as described in the column of Examples described later.

The shore A hardness can be arbitrarily changed depending on the comonomer composition ratio of the 4-methyl-1-pentene / propylene copolymer (A), the mixing ratio of the components in the resin composition, and the like, and the shore A hardness is the above. Within the range, the molded product is excellent in flexibility.

In the resin composition of the present disclosure, the elastic modulus (%) defined by the following formula is preferably 0% to 30%, more preferably 0% at room temperature (23 ° C.) in the molded body of the resin composition. It is -20%, more preferably 0% -15%.
Further, the elastic modulus (%) is preferably 5% to 30%, more preferably 10% to 25%, still more preferably 15% to 20% at 40 ° C., which is a temperature condition assuming the oral cavity. ..
Repulsive modulus (%) = (rebound height) (mm) / 460 x 100
Details of the measurement conditions and the like for the elastic modulus (%) are as described in the column of Examples described later.

The elastic modulus is controlled by the comonomer composition ratio of the 4-methyl-1-pentene / propylene copolymer (A) or the mixing ratio of the copolymer (A) and the polymer (B) in the resin composition. For example, by setting the 4-methyl-1-pentene content to 20 mol% to 65 mol%, it becomes easy to keep the elastic modulus within the above range.

It is preferable that the resin composition of the present disclosure has a melting point Tm measured by a differential scanning calorimeter (DSC) of less than 110 ° C. or not observed.
Thereby, a resin composition having suppressed crystallinity can be obtained.
By controlling the comonomer composition ratio of the 4-methyl-1-pentene-propylene copolymer (A), it becomes easy to set the melting point Tm in the above range.

(Graft denaturation)
To the extent that the object of the present disclosure is not impaired, a part or all of the 4-methyl-1-pentene-propylene copolymer (A) may be graft-modified, and a part or all of the polymer (B) may be modified. May be graft-modified. Examples of the polar compound used for graft modification and the method for graft modification include conventionally known compounds and methods, and for example, the compounds and methods described in JP-A-2008-127440 can be adopted.

The graft amount of the modified graft is usually 0.1% by mass to 40% by mass, preferably 0.2% by mass to 30% by mass, and more preferably 0.2% by mass to 20% by mass.
When the 4-methyl-1-pentene-propylene copolymer (A) or the polymer (B) is graft-modified, it is superior in terms of compatibility or adhesiveness of the composition.

≪Mouthguard sheet≫
The mouthguard sheet of the present disclosure comprises a molded body of the resin composition of the present disclosure.
The resin composition of the present disclosure can be suitably used in producing a mouthguard.
That is, the resin composition of the present disclosure is suitable as a resin composition for a mouthguard.
The molded body constituting the mouse guard sheet of the present disclosure can be obtained by subjecting the resin composition of the present disclosure to any molding method such as extrusion molding, calendar molding, press molding, injection molding, vacuum molding, pressure molding, vacuum pressure molding and the like. It can be manufactured by molding into a sheet.

≪Mouthguard≫
The mouthguards of the present disclosure include the mouthguard sheets of the present disclosure.
The mouthguard of the present disclosure can be manufactured by using the mouthguard sheet of the present disclosure made of a molded product of the resin composition of the present disclosure.
The mouthguard of the present disclosure is, for example, International Publication No. 2002/98521, Japanese Patent Application Laid-Open No. 2010, by the same method as the conventional mouthguard except that the material is the resin composition of the present disclosure or the sheet for the mouthguard. It can be produced by the method described in -131181. More specifically, a method of heating the mouthguard sheet until it softens and manufacturing the mouthguard along the dentition model or the jaw model, and creating a concave mold using the dentition model or the jaw model. Then, the mouthguard can be manufactured by a method of injecting the resin composition into the mouthguard to manufacture the mouthguard or the like.

Since the mouthguard of the present disclosure contains the resin composition of the present disclosure excellent in various properties described above, it has the following advantages.
-Since the peak value is 0.40 or more, the impact absorption of the material at the operating speed at the time of biting can be increased, so that even if it is thin, not only the wearing feeling is excellent but also the impact absorption is enhanced. can.
-By having a peak value of 1.27 or less, the elastic modulus of the material at the operating speed at the time of biting can be lowered, so that the fit is excellent, especially when the mouth is strongly bitten, and the EVA mouthpiece is made of EVA. Compared to the guard, it has less rubbery feeling and can be excellent in chewing comfort.
-When the peak value is 1.27 or less, the shore A hardness of the material near the body temperature can be lowered, so that the shore A hardness of the material follows the unevenness of the teeth and the wearing feeling is excellent.
-When the peak value is 1.27 or less, the material does not feel sticky, and it is possible to facilitate grinding during mouthguard molding.
-Since the peak value is 0.40 or more, the wear resistance of the material is high and the durability can be excellent.
-When the resin composition of the present disclosure contains the copolymer (A), it has no odor and has less residual double bonds as compared with the styrene-based elastomer mouthguard, so that it is excellent in quality stability.

Hereinafter, the present disclosure will be described by way of examples, but the present disclosure is not limited to these examples.

[Measurement conditions, etc.]
The measurement conditions and the like of the physical properties in the examples are as follows.

<Manufacturing method of various measurement press sheets>
Each of the resin compositions of Examples and Comparative Examples was sheet-molded at a pressure of 10 MPa using a hydraulic heat press machine manufactured by Kondo Metal Industry Co., Ltd. set at 190 ° C. to prepare a press sheet. In the case of a sheet with a thickness of 1 mm to 3 mm (spacer shape; 80 x 80 x 0.5 to 3 mm on a plate with a thickness of 240 x 240 x 2 mm, 4 pieces), the residual heat is about 5 to 7 minutes, and 1 to 1 at 10 MPa. After pressurizing for 2 minutes, another hydraulic heat press machine manufactured by Kondo Metal Industry Co., Ltd., which was set at 20 ° C., was used to compress at 10 MPa and cooled for about 5 minutes to prepare a sample for measurement. A brass plate having a thickness of 5 mm was used as the hot plate.

<Manufacturing method of mouthpieces for various measurements>
After each 2 mm thick press sheet obtained above is softened by heating, the air between the press sheet and the tooth-shaped plaster model is used by a vacuum forming machine (airbag XQ, manufactured by Yamahachi Dental Industry Co., Ltd.). By inhaling and creating a vacuum, the press sheet was brought into close contact with the tooth-shaped gypsum model to prepare a mouthpiece that fits the tooth-shaped gypsum model.

〔composition〕
The 4-methyl-1-pentene and propylene contents in the copolymer (A) were measured by ¹³ C-NMR by the following equipment and conditions. Using ECP500 type nuclear magnetic resonance equipment manufactured by JEOL Ltd., ortho-dichlorobenzene / heavy benzene (80/20% by volume) mixed solvent, sample concentration 55 mg / 0.6 mL, measurement temperature 120 ° C., observation nucleus ¹³ C (125 MHz), sequence is single pulse proton decoupling, pulse width is 4.7 μs (45 ° pulse), repetition time is 5.5 seconds, integration frequency is 10,000 times or more, 27.50 ppm is the standard for chemical shift. Measured as a value.

〔density〕
The density of the copolymer (A) was calculated from the mass of each sample measured in water and air using an ALFA MIRAGE electronic hydrometer MD-300S according to ASTM D 1505 (underwater substitution method).

[Ultimate viscosity]
The ultimate viscosity [η] was measured at 135 ° C. using a decalin solvent.

[Molecular weight (Mw, Mn) / Molecular weight distribution (Mw / Mn)]
For the molecular weight of the copolymer (A), a liquid chromatograph: ALC / GPC 150-C plus type manufactured by Waters (integrated type with a suggested refractometer detector) was used, and GMH6-HT × 2 and GMH6 manufactured by Tosoh Corporation were used as columns. -HTL x 2 were connected in series, o-dichlorobenzene was used as a mobile phase medium, and the measurement was performed at a flow rate of 1.0 ml / min and 140 ° C.
The obtained chromatogram was analyzed by a known method using a calibration curve using a standard polystyrene sample to calculate Mw / Mn value, Mw value and Mn value. The measurement time per sample was 60 minutes.

[Shore A hardness]
In the measurement of Shore A hardness (based on JIS K6253), a press sheet having a thickness of 3 mm was used as a measurement sample, and the scale was read 15 seconds after the needle was contacted.
The measurement was performed at both 37 ° C. and room temperature (23 ° C.).

[Dynamic viscoelasticity]
A press sheet having a thickness of 3 mm was prepared, and a strip piece of 45 mm × 10 mm × 3 mm used for dynamic viscoelasticity measurement was cut out. Using MCR301 manufactured by ANTONPaar, the temperature dependence of dynamic viscoelasticity from -40 to 180 ° C. was measured at a frequency of 10 rad / s, and the loss tangent (tanδ) due to the glass transition temperature was the peak value (maximum value). ) (Hereinafter referred to as “peak temperature”) and the peak value of the loss tangent (tan δ) at that time were measured.

[Repulsive modulus]
A press sheet with a thickness of 6 mm was prepared, and in accordance with JIS K6400, the rebound height L (mm) when a 16.310 g rigid sphere was dropped from a height of 460 mm onto this press sheet at 37 ° C. The measurement was performed, and the rebound resilience defined by the following formula was obtained.
Repulsive modulus (%) = L (mm) / 460 × 100

[Mouthpiece separability]
When the mouthpiece after vacuum forming was peeled off from the tooth profile plaster model, whether or not the sheet had a large shrinkage and adhesiveness and it was necessary to apply an excessive force was evaluated according to the following criteria and used as an index of separability.
~ Evaluation criteria ~
A: When the mouthpiece was peeled off from the tooth profile plaster model, it could be peeled off without using a mold release agent (fluorine-based mold release agent, Daikin, manufactured by Daikin Industries, Ltd.) and pliers.
B: When peeling the mouthpiece from the tooth profile plaster model, a mold release agent (fluorine-based mold release agent, Die-free, Daikin Industries, Ltd.) was not used, but it was necessary to use pliers.
C: When peeling the mouthpiece from the tooth profile plaster model, it was necessary to use a mold release agent (fluorine-based mold release agent, Daikin, Daikin Industries, Ltd.) and pliers.

[Mouthpiece workability]
After the mouthpiece was peeled off from the tooth profile plaster model, the workability when molding it into the shape of the mouthpiece was evaluated according to the following criteria.
~ Evaluation criteria ~
A: No excessive force was required during processing, the amount of polishing was small because the end face of the mouthpiece was not rough, and the mouthpiece was not melted by the heat generated during polishing.
B: No excessive force was required during processing, and the end face of the mouthpiece was as rough as usual, but the heat generated during polishing melted the mouthpiece.
C: Excessive force was required during processing, and the amount of polishing was large because the end face of the mouthpiece was rough, and the heat generated during polishing melted the mouthpiece.

[Evaluation of mouthpiece fit]
The wearing feeling of each obtained mouthpiece was evaluated according to the following criteria.
It is determined that the following A and B have a good fit, and the following C and D have a poor fit.
~ Evaluation criteria ~
A: When bitten, the force to return to the original shape was small, and the feeling when chewed was good.
B: There was a force to return to the original shape when chewed, but the feeling of repulsion when chewed was weak.
C: When bitten, the force to return to the original shape was large, and the feeling of repulsion when chewed was strong.
D: When bitten, the force to return to the original shape was very large, and the feeling of repulsion when chewed was very strong.

[Evaluation of odor]
The manufactured mouthpiece was evaluated for odor.

[Crystallinity evaluation]
For the manufactured mouthpiece, the melting point Tm can be measured by a differential scanning calorimeter (DSC), or if it can be measured, the value of the melting point Tm is measured.

-Synthesis example 1-
An autoclave made of SUS with a stirring blade having a capacity of 1.5 liters sufficiently substituted with nitrogen was charged with 300 ml of normal hexane (dried on a dry nitrogen atmosphere, activated alumina) and 450 ml of 4-methyl-1-pentene at 23 ° C. .. 0.75 ml of a 1.0 mmol / ml toluene solution of triisobutylaluminum (TIBAL) was charged into this autoclave, and the stirrer was rotated.
Next, the autoclave was heated to an internal temperature of 60 ° C. and pressurized with propylene so that the total pressure became 0.40 MPa (gauge pressure). Subsequently, 1 mmol of methylaluminoxane prepared in advance in terms of Al, diphenylmethylene (1-ethyl-3-t-butyl-cyclopentadienyl) (2,7-di-t-butyl-fluorenyl) zirconium 0.34 ml of a toluene solution containing 0.01 mmol of dichloride was pressed into an autoclave with nitrogen to initiate polymerization. During the polymerization reaction, the temperature was adjusted so that the temperature inside the autoclave was 60 ° C. 60 minutes after the start of the polymerization, 5 ml of methanol was press-fitted into the autoclave with nitrogen to stop the polymerization, and the autoclave was depressurized to atmospheric pressure. Acetone was poured into the reaction solution with stirring.
The obtained powdery polymer containing the solvent was dried at 100 ° C. under reduced pressure for 12 hours to obtain a polymer (4-methyl-1-pentene-propylene copolymer (A)).
The obtained polymer weighed 36.9 g, and the 4-methyl-1-pentene content in the polymer was 72.5 mol% and the propylene content was 27.5 mol%. Table 1 shows the results of measurements for various physical properties.

[Example 1]
The polymer (copolymer (A)) and Vistamaxx (registered trademark) 6202 (polymer (B), propylene / α-olefin copolymer, manufactured by Exxon Mobile Co., Ltd.) obtained in Synthesis Example 1 are shown in Table 2. The mixture was mixed at the described mixing ratio to obtain a resin composition.
Using the obtained resin composition, a press sheet and a mouthpiece having a thickness of 1 mm to 3 mm were prepared.
The results for each evaluation are shown in Table 2.

[Examples 2 to 7 and Comparative Examples 1 to 4]
A resin composition was obtained in the same manner as in Example 1 except that the copolymer (A) shown in Table 2 and the polymer (B) shown in Table 2 were mixed at the mixing ratio shown in Table 2. rice field.
Using the obtained resin composition, a press sheet and a mouthpiece having a thickness of 1 mm to 3 mm were prepared.
The results for each evaluation are shown in Table 2.

In Table 2, the indication of "-" means that the corresponding component is not contained or the result of the corresponding item does not exist.
The details of the description in Table 2 are as follows.
-Toughmer (registered trademark) DF840: Ethylene / α-olefin copolymer (manufactured by Mitsui Chemicals, Inc.)
・ Hybler 5127: Hydrogenated styrene / isoprene / styrene copolymer (manufactured by Kuraray Co., Ltd.)
-GC Impact Guard: Mouth guard material using styrene / α-olefin block copolymer (manufactured by GC Corporation)

As shown in Table 2, the resin composition in which the peak value of loss tangent (tan δ) by dynamic viscoelasticity measurement at a frequency of 10 rad / s is 0.40 to 1.27, and the temperature of the peak value is 22 ° C. or higher. In the examples using the material, the separability when separated from the plaster mold or the like after manufacturing the molded body was excellent, and the chewing comfort when chewed was good.

The resin composition of the example was able to suppress the rebound resilience in the produced press sheet as compared with the resin composition of the comparative example. Therefore, when the prepared mouthpiece was attached, it did not feel like rubber and fits well to the dentition and the oral mucosa.

On the other hand, Comparative Example 1 in which the peak value of tan δ was 1.70 was inferior in separability and processability.
Comparative Example 2 in which the peak value of tan δ was 0.30 was inferior in workability and fit.
Comparative Example 3 in which the temperature of the peak value of tan δ was 20 ° C. was inferior in separability.
Comparative Example 4, in which the peak value of tan δ was 0.30 and the temperature of the peak value of tan δ could not be measured, was inferior in wearing comfort.

The resin composition of Comparative Example 1 could not suppress the rebound resilience in the produced press sheet. Therefore, when the prepared mouthpiece was attached, it felt like rubber and did not fit well to the dentition and the oral mucosa.

In the resin composition of Comparative Example 2, the prepared mouthpiece adhered to the gypsum mold, it was difficult to separate it from the gypsum mold, and excessive force was applied to damage the gypsum mold. Along with this, a part of the shape of the mouthpiece could not be retained, which made it unsuitable as a mouthpiece.

In the resin composition of Comparative Example 3, the prepared mouthpiece adhered to the gypsum mold, and it was difficult to separate it from the gypsum mold. Also, the mouthpiece had an odor.
Further, the high blur 5127 was inferior in lightness because the density was 940 kg / m ³ .

Among the above examples, Examples 2 to 7 having a peak value of tan δ of 1.2 or less were superior in separability as compared with Example 1 having a peak value of tan δ of 1.25. ..

Claims (9)

A resin composition in which the peak value of loss tangent (tan δ) by dynamic viscoelasticity measurement at a frequency of 10 rad / s is 0.40 to 1.27, and the temperature of the peak value is 22 ° C. or higher. The resin composition according to claim 1, wherein the Shore A hardness at 37 ° C. is 75 or less. A structural unit (i) derived from 15 mol% to 80 mol% 4-methyl-1-pentene and a structural unit (ii) derived from 20 mol% to 85 mol% propylene (provided that the structural unit (i) is used. The sum of the ratio of the above and the ratio of the constituent unit (ii) is 100 mol%.)
At least one polymer (B) selected from the group consisting of a thermoplastic resin other than the 4-methyl-1-pentene-propylene copolymer (A) and rubber, and the polymer (B).
The resin composition according to claim 1 or 2. The polymer (B) is isotactic polypropylene, poly 1-butene, poly 4-methyl-1-pentene, ethylene / α-olefin copolymer, propylene / α-olefin copolymer and 1-butene / α. -The resin composition according to claim 3, which is at least one selected from the group consisting of olefin polymers. The claim that the polymer (B) is at least one selected from the group consisting of an ethylene / α-olefin copolymer, a propylene / α-olefin copolymer and a 1-butene / α-olefin copolymer. 3 or the resin composition according to claim 4. 30 parts by mass to 70 parts by mass of the 4-methyl-1-pentene / propylene copolymer (A) and 70 parts by mass to 30 parts by mass (however, the 4-methyl-1-pentene / propylene copolymer (however, the 4-methyl-1-pentene / propylene copolymer) The resin composition according to any one of claims 3 to 5, which contains the polymer (B) of (A) and the polymer (B) in a total amount of 100 parts by mass. thing. The resin composition according to any one of claims 1 to 6, which is a resin composition for a mouthguard. A mouthguard sheet made of a molded product of the resin composition according to any one of claims 1 to 7. A mouthguard including the mouthguard sheet according to claim 8.