JP2021091821A - Molding and screening method - Google Patents

Abstract

To provide a molding having excellent elongation properties, and a method for screening a composition that can suitably provide the molding, conveniently and without the influence of thickness of a sample.SOLUTION: A molding contains a polymer or a cured product thereof. An elongation crystallinity (X-Y) is 3 points or more and 99 points or less, which is obtained as the difference between a degree of crystallization at 900% elongation (X%) and a degree of crystallization at no elongation (Y%).SELECTED DRAWING: None

Description

The present invention relates to a molded product having rubber properties, a composition for producing the molded product, and a screening method for these. In particular, the present invention relates to a method for screening a molded product having excellent extensibility and a composition for producing the molded product.

Molds obtained from compositions containing latex have traditionally been widely used as exhibiting rubber properties. For example, a molded product obtained from a chloroprene rubber composition containing a chloroprene polymer latex is suitably used for dipping products such as gloves, sphygmomanometer bladder, and rubber thread, especially for medical gloves.

The chloroprene polymer is known as a synthetic rubber exhibiting crystallinity. Conventionally, materials using polymer latex such as chloroprene polymer latex have good properties such as general rubber physical properties, weather resistance, heat resistance, and chemical resistance, and are used for immersion products such as gloves, and for adhesives and adhesives. , Elastic asphalt (modified asphalt), elastic cement, etc. are widely used in civil engineering and construction applications. Of these, high softness and strength are important for immersion product applications. If it is too soft, the strength will be low and it will be easily torn off, and there will be a problem of durability. There is a trade-off between softness and strength, and it is strongly desired to establish a method for quickly screening a material that has both physical properties compatible with each other. Generally, softness (modulus) and strength (breaking strength Tb) are measured by a tensile test, but there is a problem that it is difficult to calculate accurate values because the thickness changes with elongation.

For example, Patent Document 1 contains a chloroprene-based polymer latex (A), a metal oxide (B), an antioxidant (C), a surfactant (D), and a pH adjuster (E), and promotes vulcanization. The composition does not contain an agent, and the amount of tetrahydrofuran insoluble in the solid content contained in (A) is 50 to 85% by mass, and (B) is based on 100 parts by mass of the solid content of (A). 1 to 10 parts by mass, (C) 0.1 to 5 parts by mass, (D) 0.1 to 10 parts by mass, and (E) 0.01 to 5 parts by mass. Is disclosed.

Further, Patent Document 2 describes a composition for producing an elastomer film, which contains a synthetic polymer, sulfur, and a metal oxide cross-linking agent, and the total solid concentration in the composition is 5 of the composition. Compositions of up to 20% by weight are disclosed. However, the modulus and breaking strength shown in Patent Document 1 and Patent Document 2 do not take into account the change in thickness due to elongation.

International Publication No. 2016/166998 Japanese Patent Application Laid-Open No. 2009-501833

The present invention has been made in view of the above problems, and provides a method for easily screening a molded product having excellent extensibility and a composition capable of suitably providing the molded product, without being affected by the thickness of the sample. To do.

As a result of diligent studies to solve the above problems, the present inventors have used a molded sample obtained from a composition containing chloroprene rubber or the like for wide-angle scattering (WAXD) measurement in an elongated state. When the elongation crystallinity determined based on the above is in a specific range, it has been found that the composition is suitable for dipping use, and the present invention has been reached.

The present invention relates to the following items [1] to [14].
[1] The elongation crystallinity (XY) obtained as the difference between the crystallinity X% at 900% elongation and the crystallinity Y% at no elongation, which contains a polymer or a cured product thereof, is 3. A molded product characterized by having points of 99 points or less.
[2] The polymer is at least one selected from the group consisting of chloroprene rubber, isoprene rubber, natural rubber, nitrile-butadiene rubber, styrene-butadiene rubber, butadiene rubber, urethane rubber, acrylic rubber, and soft polyvinyl chloride. The molded product according to the above [1], which comprises.

[3] The molded product according to [1], wherein the polymer is chloroprene rubber.
[4] The polymer is a copolymer of chloroprene and 2,3-dichloro-1,3-butadiene, or chloroprene, 2,3-dichloro-1,3-butadiene and another monomer. It is a copolymer obtained by copolymerizing a monomer containing 5.0 to 30.0% by mass of 2,3-dichloro-1,3-butadiene in 100% by mass of all the monomer components. 1] The molded product according to.
[5] The molded product according to any one of [1] to [3], which comprises a cured product of a polymer.
[6] The polymer is in a latex state, its tetrahydrofuran insoluble content is 0 to 95% by mass, and the Z average particle size of the polymer particles is 80 nm or more and 200 nm or less. [3] Or the molded product according to [4].

[7] A method for screening a molded product containing a polymer or a cured product thereof, or a composition for producing the molded product.
Molding in which the elongation crystallinity (XY) obtained as the difference between the crystallinity at 900% elongation (X%) and the crystallinity at no elongation (Y%) is 3 points or more and 99 points or less. A screening method characterized by selecting an object.

[8] The polymer is at least one selected from the group consisting of chloroprene rubber, isoprene rubber, natural rubber, nitrile-butadiene rubber, styrene-butadiene rubber, butadiene rubber, urethane rubber, acrylic rubber, and soft polyvinyl chloride. The screening method according to [7], which comprises.
[9] The screening method according to [7] or [8], wherein the polymer is chloroprene rubber.

[10] The polymer is a copolymer of chloroprene and 2,3-dichloro-1,3-butadiene, or chloroprene, 2,3-dichloro-1,3-butadiene and another monomer. It is a copolymer obtained by copolymerizing a monomer containing 5.0 to 30.0% by mass of 2,3-dichloro-1,3-butadiene in 100% by mass of all the monomer components. 7] The screening method according to.
[11] The screening method according to any one of [7] to [10], wherein the molded product is a cured product of a polymer.

[12] The screening according to any one of [7] to [10], wherein the molded product is a molded product obtained by dipping and shaping a latex composition containing polymer particles. Method.
[13] The polymer is in a latex state, its tetrahydrofuran insoluble content is 0 to 95%, and the Z average particle size of the polymer particles is 80 nm or more and 200 nm or less, [9] or The screening method according to [10].

[14] The degree of crystallization includes single crystal structure analysis, powder crystal structure analysis, high-energy X-ray structure diffraction, magnetic scattering, wide-angle scattering (WAXD), small-angle scattering (SAXS), and micro-wide-angle scattering (μ-WAXD). It is characterized in that it is measured by one selected from micro small angle scattering (μ-SAXS), ultra small angle X-ray scattering method (USAXS), and small angle incident X-ray diffraction / scattering (GISAXS). , The screening method according to any one of [7] to [13].

According to the present invention, it is possible to provide a composition that is used for manufacturing a molded product and exhibits good immersion characteristics, and a screening method for easily determining a molded product without being affected by the thickness of a molded product sample, and has elongation characteristics. It is possible to provide an excellent molded product and a composition for producing the molded product by immersion. Further, from the composition according to the present invention, the cross-linking property of the molded product which is an immersion product can be maintained, and a molded product having stable performance can be obtained.

Hereinafter, embodiments of the present invention will be described in detail.
In the screening method according to the present invention, when a molded product is produced by immersion molding using a composition containing a polymer, a composition suitable for immersion molding and a molded product having stable performance are screened by a simple method. .. In the present specification, a polymer means a polymer in which one or more kinds of monomers are polymerized or copolymerized, and includes both a homopolymer and a copolymer.

<Composition>
The composition according to the present invention is a composition that can be suitably used for immersion molding and contains a polymer. This composition is preferably a polymer latex composition containing polymer particles, and more preferably polymer particles are dispersed.
The polymer contained in the composition may be any polymer as long as the molded product exhibits elongation crystallization, and the molded product is preferably a polymer having rubber properties. Elongated crystallization means a property in which crystals are expressed or increased as the molded product is elongated.

The polymer latex composition according to the present invention is obtained by dispersing polymer particles such as various rubbers, and the tetrahydrofuran insoluble content of the polymer is usually 0 to 95% by mass, preferably 10 to 80% by mass. The Z average particle size of the polymer particles is 80 nm or more and 200 nm or less, preferably 100 nm or more and 180 nm or less. The polymer latex composition containing such polymer particles can be suitably applied to applications for producing a molded product by immersion molding. The method for measuring the Z average particle size and the like will be described later.

Examples of such a polymer include chloroprene rubber, isoprene rubber, natural rubber, nitrile-butadiene rubber, styrene-butadiene rubber, butadiene rubber, urethane rubber, acrylic rubber, soft polyvinyl chloride, and the like, and at least these. It is preferable to contain one kind, more preferably to contain chloroprene rubber, and most preferably to be chloroprene rubber.

In the present invention, the chloroprene rubber is a polymer obtained by polymerizing or copolymerizing a monomer containing chloroprene. Chloroprene is 2-chloro-1,3-butadiene.

Chloroprene polymer latex (A)
The composition according to the present invention preferably contains a chloroprene polymer latex (A). The chloroprene polymer latex (A) contains at least (1) chloroprene (A-1) as a monomer, and further (2) 2,3-dichloro-1,3-butadiene (A-2), (3). It means a copolymer latex that may contain another copolymerizable monomer component (A-3).

The ratio of 2,3-dichloro-1,3-butadiene (A-2) as the monomer component of the copolymer is preferably 0.0 to 15.0% by mass with respect to 100% by mass of the total monomer. %, More preferably 0.0 to 10.0% by mass, still more preferably 1.0 to 9.0% by mass. When the ratio of (A-2) is 0.0% by mass or more, the stability over time of flexibility is good, and when it is 15.0% by mass or less, the crystallization of the polymer is suppressed and the flexibility is good. Become.
Here, the total number of monomers means the total amount of all the monomers constituting the (co) polymer, and chloroprene (A-1), (2) 2,3-dichloro-1,3-butadiene ( A-2) and (3) Refers to the sum of other copolymerizable monomer components (A-3).

Other copolymerizable monomer components (A-3) include 1-chloro-1,3-butadiene, butadiene, isoprene, styrene, acrylonitrile, acrylic acid and its esters, methacrylic acid and its esters, and the like. Can be mentioned. The ratio is preferably 0.0 to 10.0% by mass, more preferably 0.0 to 5.0% by mass, and further preferably 0.0 with respect to 100% by mass of the total monomer. ~ 4.0% by mass. Two or more types may be used if necessary. By reducing the content of the other monomer component (A-3) copolymerizable to 100% by mass of the monomer to 10.0% by mass or less, in addition to the tensile strength of the immersed product and the elongation during cutting, it is flexible. It is possible to maintain good sexual stability over time.

Method for preparing chloroprene polymer latex (A) As a method for preparing chloroprene polymer latex (A), emulsion polymerization can be adopted, and emulsion polymerization is particularly preferable industrially.

Emulsifier used for polymerization of chloroprene polymer latex (A):
In emulsion polymerization, it is preferable to use an emulsifier. As the emulsifier, an anionic surfactant is preferable, and ordinary rosin acid soap is particularly preferable because of the ease of coagulation operation. Other specific examples of anionic surfactants include sodium salts of naphthalene sulfonic acid condensates, sodium salts of dodecylbenzene sulfonic acid, sodium salts of dodecyl sulfate and the like.

The amount of rosin soap used is preferably 1.5 to 8.0 parts by mass, preferably 1.6 to 6.0 parts by mass, with 100 parts by mass of the monomer constituting the chloroprene polymer in terms of rosin acid. Is more preferable, and 1.7 to 5.0 parts by mass is further preferable.
The amount of the surfactant other than the loginate soap is preferably 0.1 to 8.0 parts by mass, preferably 0.7 parts by mass, with the total amount of the monomers constituting the chloroprene polymer as 100 parts by mass. ~ 7.0 parts by mass is more preferable, and 0.9 to 6.0 parts by mass is further preferable. When it is 0.5 parts by mass or more, it can be emulsified well, good polymerization heat generation control can be obtained, the formation of agglomerates is suppressed, and a good product appearance can be obtained. By adding other surfactants such as sodium naphthalenesulfonate and formaldehyde condensate, the generation of the above-mentioned aggregates can be suppressed even in a system emulsified with 1.5 parts by mass or less of rosin acid. If it is 8.0 parts by mass or less, rosin acid does not remain and it is easy to remove from the mold (former) when molding parts and peel off when using parts, and good processing and operability can be obtained. The color tone of is also good.
Two or more types of emulsifiers may be used in combination.

Polymerization initiator used for polymerization of chloroprene polymer latex (A):
A general radical polymerization initiator can be used, and there is no particular limitation. Specific examples of the polymerization initiator used in emulsion polymerization are organic or inorganic peroxides such as benzoyl peroxide, potassium persulfate and ammonium persulfate, and azo compounds such as azobisisobutyronitrile. Co-catalysts such as anthraquinone sulfonate, potassium sulfite, and sodium sulfite can be used in combination in a timely manner. Two or more types of radical polymerization initiators and co-catalysts may be used in combination.

Polymerization terminator used for polymerization of chloroprene polymer latex (A):
The terminator used to terminate the polymerization of the chloroprene polymer latex (A) may be a general terminator and is not particularly limited. As specific examples, phenothiazine, para-t-butylcatechol, hydroquinone, hydroquinone monomethyl ether, diethylhydroxylamine and the like are preferable. Two or more kinds of polymerization inhibitors may be used in combination.

Polymerization conditions of chloroprene polymer latex (A):
The polymerization temperature is preferably 21 to 60 ° C., more preferably 30 to 50 ° C., and even more preferably 35 to 45 ° C. If the temperature is 21 ° C or higher, the formation of a 1,4-trans chloroprene structure showing crystallinity is suppressed and the flexibility is increased. If the temperature is 60 ° C or lower, the temperature is lower than the boiling point of chloroprene and the polymerization proceeds smoothly. To do.

Polymerization conversion rate:
The polymerization conversion rate is preferably 60 to 100%, more preferably 75 to 95%, and even more preferably 80 to 90%. If it is 60% or more, the breaking strength after cross-linking becomes high.

Characteristics of chloroprene polymer latex (A) -Tetrahydrofuran insoluble content The tetrahydrofuran insoluble content of chloroprene polymer latex (A) is preferably 0 to 95% by mass, more preferably 5 to 95% by mass, and 10 to 95% by mass. More preferred. When the tetrahydrofuran insoluble fraction is 5% by mass or more, the cross-linking speed and breaking strength are sufficient, and peeling from a dipping mold such as a hand mold at the time of molding is easy, which is preferable. Further, when it is 95% by mass or less, the obtained molded product exhibits good flexibility, breaking strength, and elongation at the time of cutting, which is preferable.

・ PH
The pH of the chloroprene polymer latex (A) is preferably 10.5 or more and 14.0 or less, more preferably 11.5 or more and 13.9 or less, and further preferably 12.5 or more and 13.8 or less at 25 ° C. is there. Within this range, the anionic surfactant as an emulsifier is stable, and the formation of agglomerates can be suppressed, which is preferable.

-Viscosity The Brookfield viscosity of the chloroprene polymer latex (A) is preferably 5.0 mPa · s or more and 90.0 mPa · s or less, more preferably 6.0 mPa · s or more and 60.0 mPa · s or less, and even more preferably 9. It is 0.0 mPa · s or more and 40.0 mPa · s or more. When the Brookfield viscosity of the chloroprene polymer latex (A) is 90.0 mPa · s or less, the viscosity is appropriate and the handling is easy, which is preferable. When the Brookfield viscosity of the chloroprene polymer latex (A) is 5.0 mPa · s or more, the diffusion rate of the compounding additives (crosslinking agent, crosslinking accelerator, preservative, etc.) in the latex is high, and the aging time is short, which is preferable.

-Z average particle size The chloroprene polymer latex (A) is a latex in which chloroprene polymer particles are emulsified and dispersed, and the Z average particle size of the polymer particles is 80 nm or more and 200 nm or less, preferably 100 nm or more and 180 nm or less. When the Z average particle size of the chloroprene polymer particles is in this range, when the Z average particle size is 100 nm or more, dehydrogenation from the chloroprene polymer particles is suppressed, the stability of the chloroprene polymer particles is obtained, and aggregates are formed. It is less likely to occur. Further, since the amount of rosin acid soap at the time of emulsification can be obtained at 180 nm or less, good emulsification can be obtained, good polymerization heat generation control, suppression of agglutination formation and good product appearance can be obtained. The Z average particle size can be measured by a known method, but can be preferably determined by a dynamic light scattering photometer.

Compositions Containing Chloroprene Polymer Latex (A) Chloroprene Polymer Latex (A) is generally susceptible to deterioration by oxygen. The chloroprene polymer latex (A) may be used as it is as a composition for producing a molded product by immersion molding, but in the present invention, an acid receiving agent or an antioxidant as long as the effect of the present invention is not impaired. It is preferable to prepare a composition containing a stabilizer such as.

In the present invention, by adding a metal oxide (B), a cross-linking accelerator (C), a cross-linking agent (D), and an antioxidant (E) to the chloroprene polymer latex (A), if necessary. , A composition capable of forming a dipping product having sufficient tensile strength and flexibility can be obtained. Among the raw materials used, those that are insoluble in water and those that destabilize the colloidal state of the chloroprene polymer latex are added to the chloroprene polymer latex after preparing an aqueous dispersion in advance.

Metal oxide (B)
Since the chloroprene polymer is generally susceptible to deterioration due to oxygen, it is preferable to add a metal oxide for the purpose of receiving acid and preventing oxidation. The metal oxide (B) is not particularly limited, and specific examples thereof include zinc oxide, lead dioxide, and trilead tetraoxide, and zinc oxide is particularly preferable. These can also be used in combination of two or more. Further, it is possible to carry out cross-linking more effectively by using it in combination with a cross-linking accelerator described later.

The amount of these metal oxides (B) added is preferably 0.1 to 20.0 parts by mass, more preferably 0.5 to 15.0 parts by mass, based on 100 parts by mass of the solid content of the chloroprene polymer latex. 1.0 to 10.0 parts by mass is further preferable, 2.0 to 9.0 parts by mass is even more preferable, and 3.0 to 8.0 parts by mass is particularly preferable. When the amount of the metal oxide (B) added is 0.1 parts by mass or more, a sufficient crosslinking rate can be obtained. At 20.0 parts by mass or less, the cross-linking rate becomes appropriate, scorch is suppressed, the colloidal stability of the chloroprene polymer latex (A) composition is good, and problems such as sedimentation are less likely to occur.

Crosslink accelerator (C)
As the cross-linking accelerator (C), thiuram-based, dithiocarbamate-based, thiourea-based, and guanidine-based, which have been generally used for cross-linking the chloroprene polymer latex (A), are used. Examples of the thiuram-based cross-linking accelerator include tetraethyl thiuram disulfide and tetrabutyl thiuram disulfide. Examples of the dithiocarbamate-based cross-linking accelerator include sodium dibutylthiodicarbamate, zinc dibutylthiodicarbamate, zinc diethylthiodicarbamate and the like. Examples of the thiourea-based cross-linking accelerator include ethylenethiourea, diethylthiourea, trimethylthiourea, N, N'-diphenylthiourea (DPTU) and the like. Examples of the guanidine-based cross-linking accelerator include 1,3-diphenylguanidine (DPG) and 1,3-di-o-tolylguanidine. Two or more kinds of cross-linking accelerators may be used in combination. The amount of these cross-linking accelerators (C) added is preferably 0.1 to 10.0 parts by mass, preferably 0.2 to 10.0 parts by mass, based on 100 parts by mass of the solid content of the chloroprene polymer latex (A). 7.0 parts by mass is more preferable, 0.3 to 5.0 parts by mass is further preferable, 0.3 to 3.0 parts by mass is even more preferable, and 0.5 to 1.5 parts by mass is particularly preferable. When the amount of the cross-linking accelerator (C) added is 0.1 parts by mass or more, a sufficient cross-linking rate can be obtained. Further, an appropriate cross-linking rate can be obtained at 10.0 parts by mass or less, scorch is suppressed, and agglomerates and the like are less likely to occur. Further, the crosslink density of the molded product becomes appropriate, and good flexibility can be obtained.

Crosslinking agent (D)
As the cross-linking agent (D), a general cross-linking agent can be used, and there is no particular limitation. As the cross-linking agent, sulfur, a sulfur compound, an organic peroxide and the like can be used. These can also be used in combination of two or more.

The cross-linking agent (D) does not necessarily have to be used, but when the cross-linking accelerator (C) alone is insufficient for cross-linking, the cross-linking agent (D) is usually used in combination. Examples of the cross-linking agent (D) include sulfur-based cross-linking agents (powdered sulfur, surface-treated sulfur, precipitated sulfur, colloidal sulfur, and insoluble sulfur) and organic peroxide-based cross-linking agents (di-t-butyl peroxide, cumene hydroperoxide, bis). (Α, α-Dimethylbenzyl) peroxide, benzoyl peroxide, t-butylperbenzoate, 2,2-dit-butylperoxybutane, azobisisobutyronitrile) are preferable, and sulfur is particularly preferable. The amount of the cross-linking agent (D) added is preferably 0.1 to 7.0 parts by mass, more preferably 0.2 to 5.0 parts by mass, based on 100 parts by mass of the solid content of the chloroprene polymer latex (A). It is preferable, and 0.3 to 3.0 parts by mass is more preferable. When it is 0.1 part by mass or more, a sufficient promoting effect is obtained, and conversely, when it is 7.0 parts by mass or less, a good cross-linking rate is obtained, it is difficult to scorch, it is easy to manage the cross-linking, and the heat resistance after cross-linking is good. Good product is obtained, and bleeding is unlikely to occur.

Antioxidant (E)
As the antioxidant (E), it is preferable to use an antioxidant (heat resistant old protection) for the purpose of imparting heat resistance, an ozone antioxidant (ozone old protection), and the like. It is preferable to use these in combination. As heat resistance, diphenylamines such as di (4-octylphenyl) amine, p- (p-toluene-sulfonylamide) diphenylamine and 4,4'-bis (α, α-dimethylbenzyl) diphenylamine are only heat resistant. However, it is preferable because it has less stain resistance (transition such as discoloration). As ozone protection, N, N'-diphenyl-p-phenylenediamine (DPPD) or N-isopropyl-N'-phenyl-p-phenylenediamine (IPPD) can also be used. However, in general, when appearance, particularly color tone and hygiene are important, such as medical gloves, hindered phenolic antioxidants are particularly preferable. The amount of the antioxidant (E) added is preferably 0.1 to 10.0 parts by mass, preferably 0.2 to 7.0 parts by mass (dry mass part) with respect to 100 parts by mass of the solid content of the chloroprene polymer latex (A). .0 parts by mass is more preferable, 0.3 to 5.0 parts by mass is further preferable, 0.5 to 4.0 parts by mass is even more preferable, and 1.0 to 3.0 parts by mass is particularly preferable. When the amount of the antioxidant (E) added is 0.1 parts by mass or more, a sufficient antioxidant effect can be obtained, and when it is 10.0 parts by mass or less, good cross-linking can be obtained or a desired color tone can be obtained. Therefore, it is preferable.

The composition containing the chloroprene polymer latex (A) and the chloroprene polymer latex (A) has been described in detail above, but in the present invention, other polymer latex is used instead of the chloroprene polymer latex (A). Even when it is used, it can be similarly used as a composition for producing a molded product by immersion molding.

Production of Molded Product The molded product of the present invention can be produced using a composition containing the above-mentioned polymer latex, which can be used for producing a molded product by immersion molding, and is preferably a chloroprene polymer latex (preferably a chloroprene polymer latex). It can be produced by using a composition containing A). The molded product of the present invention contains a polymer in a polymer latex composition or a cured product (crosslinked product) thereof.
In the present invention, a polymer latex composition such as a composition containing a chloroprene polymer latex (A) is used, and after immersion and solidification by a usual method, leaching (removal of water-soluble impurities), drying, and then cross-linking are performed. By proceeding the steps in this order, a film-shaped molded product can be obtained.

When a molded product such as gloves is obtained by such a step using a composition containing chloroprene polymer latex (A), the cross-linking temperature is particularly high as compared with natural rubber in order to obtain a desired degree of cross-linking. Therefore, it is necessary to be careful because high temperature is required. In order to avoid problems in product appearance, such as blisters and pinholes, it may be necessary to perform rough drying at a relatively low temperature in the range of 70 to 100 ° C. in advance before crosslinking. The cross-linking temperature is 120 to 140 ° C., and the cross-linking time is 15 minutes to 2 hours. By carrying out a tensile test on the crosslinked film, it is possible to measure a predetermined tensile tensile stress (also referred to as modulus or elastic modulus), tensile strength, and elongation at the time of cutting. When the desired degree of cross-linking is achieved, this chloroprene rubber molded product has a 300% elastic modulus (modulus) of 0.3 to 1.2 MPa, a tensile strength of 10 MPa or more, more preferably 12 MPa or more, and an elongation at cutting of 900. % Or more, preferably 1000% or more.

<Screening method>
The screening method of the present invention is a screening method applicable when a composition containing a polymer latex is dip-molded to produce a molded product having rubber properties, and is a composition suitable for dipping use and stable. It is suitable as a screening method for performance molded products.
The molded product according to the present invention exhibits elongated crystallization. In the screening according to the present invention, the degree of elongation crystallinity of the molded product sample is determined, thereby evaluating the molded product and the composition.
Here, elongation crystallization is a phenomenon in which molecules oriented in the elongation direction form crystals when rubber is stretched, and is observed in molded products having rubber properties such as natural rubber and chloroprene rubber.

Elongation Crystallinity In the present invention, the elongation crystallization degree of a molded product sample is the crystallinity X% at 900% elongation and the crystallization degree Y at no elongation of a molded product such as a film having rubber properties. It is calculated as the difference (XY) points from%. Therefore, the crystallization degree of the molded product sample in which the crystallization degree without elongation is 0% matches the crystallization degree at the time of 900% elongation. Here, the crystallinity at 900% elongation means that the molded product was stretched to a length (900%) 9 times in one direction with respect to the length (100%) in the non-stretched state (non-stretching). It means the value of crystallinity measured in the state.

That is, in the present invention, the degree of extended crystallinity of the molded product can be calculated by the following formula.
Elongated Crystallinity (Point) = 900% Crystallinity at Elongation (X%) -Crystallinity at No Elongation (Y%)
The degree of crystallization of the molded product at 900% elongation and no elongation can be measured by a known method, and preferably, the degree of crystallization is determined by single crystal structure analysis, powder crystal structure analysis, and high-energy X-ray structure. Diffractive, magnetic scattering, wide-angle scattering (WAXD), small-angle scattering (SAXS), micro-wide-angle scattering (μ-WAXD), micro-small-angle scattering (μ-SAXS), ultra-small-angle X-ray scattering method (USAXS), small-angle incident X-rays It can be measured by one selected from diffraction / scattering (GISAXS). Among these, it is preferable to measure by the wide-angle scattering (WAXD) method (also referred to as wide-angle X-ray diffraction method).

The molded product of the present invention preferably has an elongation crystallinity of 3 points or more and 99 points or less, preferably 5 points or more and 80 points or less, and more preferably 10 points or more and 40 points or less.
The degree of extended crystallization of a molded product can be determined by measuring using a molded product sample, but in the present invention, the shape of the molded product sample when determining the degree of extended crystallization is not limited. That is, it suffices if the crystallinity (Y%) of the molded product sample without elongation and the crystallinity (X%) of the molded product sample at 900% elongation can be measured, and what is the shape such as the thickness of the molded product sample? It may be about.

In the present invention, when a molded product such as a film is obtained from a composition containing polymer particles by a dipping method or the like, the composition can be obtained by confirming that the degree of extended crystallization of the molded product satisfies the above range. It is possible to easily determine whether or not the composition is suitable for the purpose of producing a stable molded product.

Hereinafter, the present invention will be described in more detail based on Examples, but the present invention is not limited to these Examples.
<Measurement / evaluation method>
In the following Examples and Comparative Examples, various physical properties related to the polymer latex and the crosslinked molded product were measured or evaluated as follows.

Evaluation of Polymer Latex / Polymerization Conversion Rate The polymerized latex after polymerization was collected, and the polymerization conversion rate was calculated from the solid content after drying at 141 ° C. for 30 minutes. The solid content and the polymerization conversion rate were calculated by the following formulas.
Solid content after polymerization (mass%)
= [(141 ° C., mass after drying for 30 minutes) / (mass of latex before drying)] × 100
Polymerization conversion rate [%] = [(polymer production amount / chloroprene monomer charge amount)] × 100
Here, the amount of polymer produced was determined by subtracting the solid content other than the polymer from the solid content after polymerization. The components other than the polymer that did not volatilize under the condition of 141 ° C. were calculated from the amount of the polymer charged.

• Place the Brookfield Viscosity Specimen in a 300 mL polypropylene beaker to ensure that there are no air bubbles inside. Using the B-type viscometer shown in JIS K7117-1: 1999, the second viscosity as a result of continuous measurement under the following conditions and the measured value is within 5% is defined as the recorded viscosity.
Equipment: BROOKFIELD Viscometer DV-E LVDVE115
Spindle: No. 1 Spindle rotation speed: 60 rpm
Temperature: 20 ° C

-Tetrahydrofuran insoluble fraction 1 g (water content; 35 to 65% by mass) of the polymer latex was added dropwise to 100 ml of tetrahydrofuran, shaken with a shaker (SA300) manufactured by Yamato Scientific Co., Ltd. for 10 hours, and then centrifuged (stock). Separate the dissolved phase of the supernatant at 14,000 rpm for 60 minutes at 14,000 rpm (H-9R) manufactured by Kokusan Co., Ltd., evaporate and dry tetrahydrofuran at 100 ° C. for 1 hour, calculate the dissolved content and subtract. , Tetrahydrofuran insoluble fraction (% by mass).
Tetrahydrofuran insoluble fraction (% by mass)
= [1-[(Mass of dry matter (g)) / (Amount of solids in 1 g of polymer latex (g))]} × 100

-Z average particle size (nm)
The Z average particle size of the polymer particles in the polymer latex is determined by using a solution obtained by diluting latex with pure water to 0.01 to 0.1% with a dynamic light scattering photometer (ZETASIER (registered trademark) manufactured by Malvern Panalytic Ltd.). Obtained by Nano-S).

Evaluation and mechanical properties of crosslinked molded product According to JIS-K6251-2017, the crosslinked sheet was cut with a No. 6 dumbbell to obtain a test piece. The thickness of the test piece was 0.15-0.25 mm.
Tensile tests were performed on the film test pieces according to JIS-K6251-2017, and 100% elongation modulus (M100, MPa), tensile strength (Tb, MPa), and cutting elongation (Eb, MPa) at 23 ° C. %) Was measured.

・ Wide-angle scattering (WAXD)
It was carried out in the BL03XU second experiment hatch of SPring-8 operated by the High Brightness Photon Science Research Center. A self-made uniaxial stretching machine is installed on the gantry of the experimental hatch, and the cross-linked film of chloroprene rubber is uniaxially stretched to 900% in the non-stretched state, and the film is irradiated with X-rays from the vertical direction to wide-angle Scattering (WAXD) was measured.
The camera length was 76 mm when stretched, the camera length was 77 mm when unstretched, and the X-ray wavelength was 0.1 nm, and Piratus 1M was used as the detector. Partial integration was performed for the region of 43 ° to 50 ° of the two-dimensional scattering image, and the scattering intensity (Ix) after subtracting the background scattering was plotted against the scattering vector q to obtain a scattering profile.

-Crystallity The crystallinity of chloroprene was calculated based on the measurement results of the strong peak derived from chloroprene (2θ [CuKα] = 19.83 °) using the WAXD data obtained above.
In the method of calculating the crystallinity, the crystallinity was obtained by separating the crystalline region and the amorphous region and measuring the integrated strength of each.
Crystallinity (%) = Crystalline peak area / (Crystalline peak area + Amorphous peak area) x 100
PDXL2 (manufactured by Rigaku Co., Ltd.) was used as the software used, and the peak fitting was manually performed so that the position of the strong peak was particularly fitted (see the analysis conditions below for the conditions).

[Data analysis conditions]
・ Smoothing: Smoothing by B-Spline (Χ threshold: 1.50)
-Background removal: Sonneveld-Visser method (peak width threshold 1.00, intensity threshold 10.00)
・ Kα2 removal: None ・ Peak search: Second-order differential method (σ cut value 6.00)
-Profile fitting: Fitting to measurement data (Peak shape: Divided pseudo Voigt function)
* For data in which only broad peaks are seen, manual processing was performed so that chloroprene-derived peaks (around 2θ = 19.83 °) and amorphous peaks (around 18.6-9 °) fit. ..

[Example 1]
-Preparation of Polymer Latex Composition Using a reactor with an internal volume of 5 liters, 1.4 kg of 2-chloro-1,3-butadiene (chloroprene) and 0.13 kg of 2,3-dichloro-1,3-butadiene And pure water 1.2 kg, disproportionate logonic acid (manufactured by Arakawa Chemical Industry Co., Ltd., R-600) 65 g, n-dodecyl mercaptan 0.91 g, sodium hydroxide 16 g, potassium hydroxide 86 g, β-naphthalene sulfonic acid 8.0 g of sodium salt of formalin condensate was charged, emulsified, disproportionated sulfonic acid was made into rosin soap, and then polymerization was carried out at 40 ° C. under a nitrogen atmosphere using potassium persulfate as an initiator. When the polymerization conversion rate reached 84%, an emulsion of phenothiazine was immediately added to terminate the polymerization. Then, the unreacted monomer was removed by steam distillation to obtain a chloroprene polymer latex (1), which is a polymer latex of the chloroprene polymer. The tetrahydrofuran insoluble content was 10.0%, the solid content ratio was 46.8%, and the Brookfield viscosity was 10.5 mPa · s.

-Preparation and Crosslinking of Immersion Film The chloroprene polymer latex (1) prepared as described above was placed in a stirring tank equipped with a three-one motor and stirred for 5 minutes to homogenize the mixture. The homogenized chloroprene polymer latex (1) was allowed to stand at room temperature (20 ° C.) for 24 hours for aging.
Zinc oxide dispersion, cross-linking accelerator and phenol in the formulation shown in Table 2 (parts by mass with respect to 100 parts by mass of dry solid content of the chloroprene polymer latex (1)) with respect to the aged chloroprene polymer latex (1). A system antioxidant dispersion was added and mixed to prepare a chloroprene polymer latex composition (1').
A ceramic plate having a length of 200 mm, a width of 100 mm, and a thickness of 5 mm was used as a mold for the dipping film, and the mold was immersed in a coagulating liquid consisting of a 30 mass% calcium nitrate aqueous solution and dried in an oven at 40 ° C. for 5 minutes. The dried mold was dipped in the chloroprene polymer latex composition (1'), pulled up to form a film, and dried in an oven at 70 ° C. for 30 minutes.
Then, it was heat-crosslinked at 130 ° C. for 20 minutes in a conventional oven, allowed to cool in the air, and then cut out from a mold to obtain a crosslinked film (crosslinked molded product).
The characteristics of the obtained crosslinked molded product were measured or evaluated as described above. The results are shown in Table 3.

[Example 2]
In the preparation of the chloroprene polymer latex (1) of Example 1, the same as in Example 1 except that when the polymerization conversion rate reached 88%, an emulsion of phenothiazine was immediately added to terminate the polymerization. The chloroprene polymer latex (2) was obtained. Table 1 shows the solid content, Brookfield viscosity, and tetrahydrofuran insoluble content of the obtained chloroprene polymer latex (2).
Next, the obtained chloroprene polymer latex (2) was used instead of the chloroprene polymer latex (1), and the amount of the additive compounded was as shown in Table 2 in the same manner as in Example 1. , Chloroprene polymer latex composition (2') was prepared, and a dipping film was prepared and crosslinked using this to obtain a crosslinked film (crosslinked molded product).
The characteristics of the obtained crosslinked molded product were measured or evaluated as described above. The results are shown in Table 3.

[Example 3, Comparative Example 1]
In the preparation of the chloroprene polymer latex (1) of Example 1, the amount of n-dodecyl mercaptan used as a chain transfer agent and the polymerization conversion rate at which polymerization was stopped were as shown in Table 1, except that Example 1 A chloroprene polymer latex was obtained in the same manner as above. Table 1 shows the solid content, Brookfield viscosity and tetrahydrofuran insoluble content of the obtained chloroprene polymer latex.
Next, instead of the chloroprene polymer latex (1), the obtained chloroprene polymer latex was used, and the amount of the additive compounded when the chloroprene polymer latex was 100 parts by mass was as shown in Table 2. Prepared a chloroprene polymer latex composition in the same manner as in Example 1, and used it to prepare a dipping film and crosslink it to obtain a crosslinked film (crosslinked molded product). The characteristics of the obtained crosslinked molded product were measured or evaluated as described above. The results are shown in Table 3.

From Table 2, in Comparative Example 1, the value of Tb / M100 was smaller than that of Examples 1 to 3, and the flexibility with respect to the breaking strength was lowered, and the balance between the breaking strength and the flexibility required for the immersed product was achieved. Can be seen to be impaired.

The composition of the present invention can be suitably used for producing a molded product which is an immersion product, and the molded product of the present invention is suitable for an immersion product such as a glove, a sphygmomanometer bladder, and a rubber thread, particularly for medical gloves and the like. Can be used. According to the screening method of the present invention, a composition suitable for producing a dipping product and a molded product having stable performance can be screened by a simple method.

Claims (14)

The elongation crystallinity (XY) obtained as the difference between the crystallinity X% at 900% elongation and the crystallinity Y% at no elongation, which contains a polymer or a cured product thereof, is 3 points or more and 99. A molded product characterized by being less than or equal to a point. The polymer contains at least one selected from the group consisting of chloroprene rubber, isoprene rubber, natural rubber, nitrile-butadiene rubber, styrene-butadiene rubber, butadiene rubber, urethane rubber, acrylic rubber, and soft polyvinyl chloride. The molded product according to claim 1, which is characteristic. The molded product according to claim 1, wherein the polymer is chloroprene rubber. The polymer is a copolymer of chloroprene and 2,3-dichloro-1,3-butadiene, or a copolymer of chloroprene and 2,3-dichloro-1,3-butadiene and another monomer. The first aspect of the present invention is a copolymerization of a monomer containing 5.0 to 30.0% by mass of 2,3-dichloro-1,3-butadiene in 100% by mass of all the monomer components. The molded product described. The molded product according to any one of claims 1 to 4, which comprises a cured product of a polymer. According to claim 3 or 4, the polymer is in a latex state, its tetrahydrofuran insoluble content is 0 to 95% by mass, and the Z average particle size of the polymer particles is 80 nm or more and 200 nm or less. The molded product described. A method for screening a molded product containing a polymer or a cured product thereof, or a composition for producing the molded product.
Molding in which the elongation crystallinity (XY) obtained as the difference between the crystallinity at 900% elongation (X%) and the crystallinity at no elongation (Y%) is 3 points or more and 99 points or less. A screening method characterized by selecting an object. The polymer contains at least one selected from the group consisting of chloroprene rubber, isoprene rubber, natural rubber, nitrile-butadiene rubber, styrene-butadiene rubber, butadiene rubber, urethane rubber, acrylic rubber, and soft polyvinyl chloride. The screening method according to claim 7, wherein the screening method is characterized. The screening method according to claim 7, wherein the polymer is chloroprene rubber. The polymer is a copolymer of chloroprene and 2,3-dichloro-1,3-butadiene, or a copolymer of chloroprene and 2,3-dichloro-1,3-butadiene and another monomer. The seventh aspect of the present invention is a copolymerization of a monomer containing 5.0 to 30.0% by mass of 2,3-dichloro-1,3-butadiene in 100% by mass of all the monomer components. The screening method described. The screening method according to any one of claims 7 to 10, wherein the molded product is a cured product of a polymer. The screening method according to any one of claims 7 to 10, wherein the molded product is a molded product obtained by dip-molding a latex composition containing polymer particles. The ninth or tenth aspect of the present invention, wherein the polymer is in a latex state, the tetrahydrofuran insoluble content thereof is 0 to 95%, and the Z average particle size of the polymer particles is 80 nm or more and 200 nm or less. Screening method. The degree of crystallization is single crystal structure analysis, powder crystal structure analysis, high-energy X-ray structure diffraction, magnetic scattering, wide-angle scattering (WAXD), small-angle scattering (SAXS), micro-wide-angle scattering (μ-WAXD), and micro-small-angle scattering. (Μ-SAXS), ultra-small angle X-ray scattering method (USAXS), and small angle incident X-ray diffraction / scattering (GISAXS). The screening method according to any one of 7 to 13.