JPWO2020149388A1 - Crosslinkable block copolymer and hot melt adhesive - Google Patents

Abstract

The present invention provides a crosslinkable block copolymer having a low viscosity, excellent coatability, and excellent adhesive physical properties, particularly peeling resistance, and a hot melt adhesive using the same. The crosslinkable block copolymer of the present invention has a polymer block A containing a monomer unit having crosslinkability and a polymer block B, and after cross-linking, 1 H pulse NMR (20 MHz) at 40 ° C. When the decay curve obtained by the Solid echo method is fitted with a two-component relaxation curve using the nonlinear minimum square method, the shorter spin-spin relaxation time T2 (1) is 40 to 90 μsec, and the spin-spin is described above. It is characterized in that the component ratio A1 of the relaxation curve having the relaxation time T2 (1) is 10 to 35%.

Description

The present invention relates to crosslinkable block copolymers and hot melt adhesives.

Acrylic adhesives are used in adhesive tapes, product labels, and the like. Further, since acrylic adhesives are excellent in transparency, heat resistance and weather resistance, they are also used in optical displays of electronic devices such as personal computers, smartphones, televisions and digital cameras.

Further, from the viewpoint of improving the usage environment, it is recommended to make the adhesive solvent-free, and the acrylic adhesive is also becoming hot-melted. Since the hot melt adhesive does not require a drying process for removing the solvent in the coating process on the support, it does not require equipment for the drying process and greatly contributes to energy saving.

In order to develop hot melt coatability in an acrylic hot melt adhesive, it is necessary to design the acrylic polymer to have a small molecular weight. However, since the adhesive property cannot be obtained by reducing the molecular weight, it is necessary to carry out a cross-linking reaction or a chain extension reaction to increase the molecular weight by cross-linking (curing) after hot-melt coating.

In Patent Document 1, at least two blocks of the non-elastomeric polymer block A and the elastomeric polymer block B composed of the (meth) acrylate-based polymer are bonded to each other, and the non-elastomeric polymer block B is obtained by ¹ H pulse NMR at 30 ° C. The spin-spin relaxation time T _{2 of the} elastomeric polymer block A is 13 to 25 microseconds, its proton component ratio is 0.05 to 0.3, and the melting point or glass transition of the non-elastomeric polymer block A. A reactive hot that uses a block copolymer having a number average molecular weight of 15,000 to 200,000 as the main component and cross-links or increases the molecular weight by heating or irradiation with active energy rays. Melt pressure-sensitive adhesive compositions are disclosed.

JP-A-2002-69412

The reactive hot-melt adhesive composition of Patent Document 1 has a significantly increased viscosity depending on the type and content of the monomers constituting the non-elastomeric polymer block A, a decrease in coatability, and adhesiveness. Also has the problem of decreasing.

The present invention provides a crosslinkable block copolymer having a low melt viscosity, excellent coatability, and exhibiting excellent adhesive physical properties (particularly peeling resistance) by crosslinking, and a hot melt adhesive using the same. ..

Crosslinkable block copolymers
Polymer block A containing a crosslinkable monomer unit and
It has a polymer block B and
After cross-linking, when the decay curve obtained by the Solid echo method in ¹ H pulse NMR (20 MHz) at 40 ° C. is fitted with a two-component transition curve using the nonlinear least squares method, the shorter spin-spin relaxation is performed. The time T ₂ (1) is 40 to 90 μsec, and the component ratio A _{1 of the} transition curve having the spin-spin relaxation time T ₂ is 10 to 35%.

The crosslinkable block copolymer is a crosslinkable block copolymer having a polymer block A and a polymer block B.
The polymer block A contains a monomer unit having crosslinkability, and contains
After cross-linking the crosslinkable block copolymer, the decay curve obtained by the Solid echo method in ¹ H pulse NMR (20 MHz) at 40 ° C. is fitted with a two-component relaxation curve using the nonlinear least squares method. The shorter spin-spin relaxation time T ₂ (1) is 40 to 90 μsec, and the component ratio A _{1 of the} relaxation curve having the spin-spin relaxation time T ₂ (1) is 10 to 35%. It is characterized by.

[Crosslinkable block copolymer]
The crosslinkable block copolymer of the present invention has a polymer block A and a polymer block B. The crosslinkable block copolymer is preferably an ABA type triblock copolymer in which the polymer block A is bonded to each of both ends of the polymer block B.

The monomer constituting the polymer block A of the crosslinkable block copolymer is not particularly limited, and examples thereof include monomers capable of performing a polymerization reaction such as radical polymerization, cationic polymerization, and anion polymerization, and have an ethylenically unsaturated bond. The monomer having is preferable.

Among the monomers constituting the polymer block A, monomers other than the monomers having crosslinkability described later, that is, monomers having no crosslinkability (hereinafter, “monomers not containing crosslinkable groups” or “non-crosslinkable monomers” Examples thereof include vinyl-based monomers, (meth) acrylic-based monomers, (meth) acrylamide-based monomers, and the like, which are excellent in radical polymerization reactivity. Therefore, (meth) acrylic-based monomers and (Meta) acrylamide-based monomers are preferable. In addition, (meth) acrylic means acrylic or methacrylic.

Examples of vinyl-based monomers include styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, α-methylstyrene, o-ethylstyrene, m-ethylstyrene, p-ethylstyrene, and 2,4-dimethyl. Styrene, pn-butyl styrene, pt-butyl styrene, pn-hexyl styrene, pn-octyl styrene, pn-nonyl styrene, pn-decyl styrene, pn-dodecyl styrene , P-methoxystyrene, p-phenylstyrene, p-chlorostyrene, styrene-based monomers such as 3,4-dichlorostyrene and the like. The vinyl-based monomer may be used alone or in combination of two or more.

Examples of the (meth) acrylic monomer include methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, n-butyl (meth) acrylate, isobutyl (meth) acrylate, and sec-butyl (meth). ) Acrylate, n-hexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, n-octyl (meth) acrylate, isooctyl (meth) acrylate, n-nonyl (meth) acrylate, isononyl (meth) acrylate, n-decyl Alkyl acrylates such as (meth) acrylate, lauryl (meth) methacrylate, stearyl (meth) acrylate, isobornyl (meth) acrylate, cyclohexyl (meth) acrylate, t-butylcyclohexyl (meth) acrylate, 3,5,5-trimethylcyclohexyl (Meta) acrylate, benzyl (meth) acrylate, phenyl (meth) acrylate, dicyclopentenyl (meth) having a saturated aliphatic ring structure such as (meth) acrylate, dicyclopentanyl (meth) acrylate, and adamantyl (meth) acrylate. ) Examples include (meth) acrylates such as acrylates. Since the crosslinkable block copolymer has an appropriate melt viscosity, has excellent coatability, and has excellent adhesive properties such as peeling resistance after cross-linking, (meth) acrylate is preferable, and saturated aliphatic group. (Meta) acrylates having a ring structure are more preferable, isobornyl (meth) acrylates, cyclohexyl (meth) acrylates, t-butylcyclohexyl (meth) acrylates, 3,5,5-trimethylcyclohexyl (meth) acrylates, dicyclopentanyls. (Meta) acrylates and adamantyl (meth) acrylates are more preferred, and isobornyl (meth) acrylates, cyclohexyl (meth) acrylates and 4-t-butylcyclohexyl (meth) acrylates are particularly preferred. The (meth) acrylic monomer may be used alone or in combination of two or more. (Meta) acrylate means methacrylate or acrylate.

Examples of the (meth) acrylamide-based monomer include N, N-dimethyl (meth) acrylamide, N, N-diethyl (meth) acrylamide, N-isopropyl (meth) acrylamide, N-phenyl (meth) acrylamide, and N-benzyl. (Meta) acrylamide, N-isobornyl (meth) acrylamide, N-cyclohexyl (meth) acrylamide, N-3,5,5-trimethylcyclohexyl (meth) acrylamide, N-dicyclopentanyl (meth) acrylamide, N-di Cyclopentenyl (meth) acrylamide, N-adamantyl (meth) acrylamide, N, N-diphenyl (meth) acrylamide and the like can be mentioned. The (meth) acrylamide-based monomer may be used alone or in combination of two or more.

Among the monomer units constituting the polymer block A, the content of the monomer unit having no crosslinkability is preferably 60% by mass or more because the peeling resistance of the crosslinkable block copolymer after cross-linking is improved. , 90% by mass or more is more preferable, 95% by mass or more is more preferable, and 98% by mass or more is particularly preferable. Among the monomer units constituting the polymer block A, the content of the monomer unit having no crosslinkability is 99.9% by mass or less because the peeling resistance of the crosslinkable block copolymer after cross-linking is improved. Is preferable, 99.8% by mass or less is more preferable, and 99.7% by mass or less is particularly preferable.

The polymer block A contains a monomer unit having crosslinkability. Since the polymer block A contains a monomer unit having a crosslinkability, the polymer block A and the polymer block B have different polarities from each other to express a layer-separated structure, and the polymer block A is expressed. By actively introducing the crosslinked structure into the polymer, the crosslinkable block copolymer has excellent peeling resistance after crosslinking.

Crosslinkable monomers (hereinafter sometimes referred to as "crosslinkable monomers") include irradiation with radiation such as ultraviolet rays and electron beams, heating, reaction with moisture (water), acids, bases and / or crosslinkers, etc. A monomer having a crosslinkable group that can be crosslinked by forming a chemical bond by the crosslinking treatment of. As the crosslinkable monomer, a monomer having a crosslinkable group that forms a chemical bond by irradiation with radiation (hereinafter, may be referred to as “radiocrosslinkable monomer”) is preferable, and the chemical bond is formed by irradiation with ultraviolet rays. A monomer having a crosslinkable group capable of forming a crosslink (hereinafter, may be referred to as “ultraviolet crosslinkable monomer”) is more preferable. “Crosslinkability” means that a chemical bond can be formed and crosslinked by a crosslinking treatment such as irradiation with radiation such as ultraviolet rays and electron beams, heating, reaction with moisture (water), acid, base and / or a crosslinking agent. Say that.

The crosslinkable group is not particularly limited, and for example, a hydroxyl group, a thiol group, a carboxyl group, a glycidyl group, an oxetanyl group, a trimethoxysilyl group, an isocyanate group, an amino group, a vinyl group, a (meth) acryloyl group and a benzophenone group. , Benzoin group, thioxanthone group and the like, preferably a glycidyl group, a benzophenone group, a benzoin group and a thioxanthone group, and more preferably a glycidyl group and a benzophenone group. In addition, (meth) acryloyl means methacryloyl or acryloyl. (Meta) acryloxy means methacryloxy or acryloxy.

The crosslinkable monomer is not particularly limited, and is, for example, 4-hydroxybutyl acrylate glycidyl ether, 4- (meth) acryloyloxybenzophenone, 4- [2-((meth) acryloyloxy) ethoxy] benzophenone, 4-. (Meta) acryloyloxy-4'-methoxybenzophenone, 4- (meth) acryloyloxyethoxy-4'-methoxybenzophenone, 4- (meth) acryloyloxy-4'-bromobenzophenone, 4- (meth) acryloyloxyethoxy- Examples thereof include 4'-bromobenzophenone, and 4-hydroxybutylacrylate glycidyl ether, 4- (meth) acryloyloxybenzophenone, and 4- [2-((meth) acryloyloxy) ethoxy] benzophenone are preferable. The monomer having a crosslinkable group may be used alone or in combination of two or more. In addition, (meth) acryloyloxy means methacryloyloxy or acryloyloxy.

Among the monomer units constituting the polymer block A, the content of the monomer unit having crosslinkability is preferably 40% by mass or less because the peeling resistance of the crosslinkable block copolymer after cross-linking is improved. It is more preferably 10% by mass or less, more preferably 5% by mass or less, and particularly preferably 2% by mass or less. The content of the crosslinkable monomer unit in the monomers constituting the polymer block A is preferably 0.1% by mass or more because the peeling resistance of the crosslinkable block copolymer after crosslinking is improved. , 0.2% by mass or more is more preferable, and 0.3% by mass or more is particularly preferable. When the crosslinkable block copolymer has a plurality of polymer blocks A, the preferable content of the crosslinkable monomer unit is preferably satisfied by at least one polymer block A, and all the weights are preferable. It is more preferable that the coalescing block A is filled.

The polymer block A is bound to the polymer block B described later, and is preferably bonded to both ends of the polymer block B. The crosslinkable block copolymer may have a polymer block A and a polymer block B, and an ABA type triblock structure is preferable. When the crosslinkable block copolymer has an ABA type triblock structure, the two polymer blocks A bonded to both ends of the polymer block B do not have to be the same and are different. You may be. That is, the two polymer blocks A bonded to both ends of the polymer block B may have the same or different types and contents of the monomer units constituting the two polymer blocks A. The molecular weights may be the same or different.

The molecular weight of the polymer constituting the polymer block A is preferably 1000 or more, more preferably 3000 or more, more preferably 5000 or more, and even more preferably 5500 or more. The molecular weight of the polymer constituting the polymer block A is preferably 50,000 or less, more preferably 30,000 or less, more preferably 25,000 or less, and even more preferably 22,000 or less. When the molecular weight of the polymer constituting the polymer block A is 1000 or more, the peeling resistance of the crosslinkable block copolymer after cross-linking is improved. When the molecular weight of the polymer constituting the polymer block A is 50,000 or less, the crosslinkable block copolymer has an appropriate melt viscosity and has excellent coatability.

When the crosslinkable block copolymer has an ABA type triblock structure, the ratio of the molecular weights of the two polymer blocks A bonded to both ends of the polymer block B is 2.4 or less. Is preferable, 2.2 or less is more preferable, and 2.0 or less is particularly preferable. When the molecular weight ratio is within the above range, a layer-separated structure can be satisfactorily formed between the polymer block A and the polymer block B after the crosslinkable block copolymer is crosslinked, and the crosslinkable block can be formed. The peeling resistance of the copolymer after cross-linking is improved. The molecular weight ratio refers to a value obtained by dividing a large molecular weight by a small molecular weight among the molecular weights of the two polymer blocks A and A.

In the present invention, the molecular weight of the polymer constituting the polymer block A is determined from the peak top molecular weight of the polymer block A partial polymer and the peak top molecular weight of the crosslinkable block copolymer. Polymer block B The value obtained by subtracting the peak top molecular weight of the partial polymer.

The monomer constituting the polymer block B of the crosslinkable block copolymer preferably has no crosslinkability (non-crosslinkability). That is, the monomer constituting the polymer block B of the polymer block B is preferably a monomer having no crosslinkable group (non-crosslinkable monomer). If the monomer constituting the polymer block B does not have crosslinkability, the peeling resistance of the crosslinkable block copolymer after cross-linking is improved.

The monomer constituting the polymer block B of the crosslinkable block copolymer is not particularly limited, and examples thereof include monomers capable of performing a polymerization reaction such as radical polymerization, cationic polymerization, and anion polymerization, and have an ethylenically unsaturated bond. The monomer having is preferable.

Examples of the monomers constituting the polymer block B include vinyl-based monomers, (meth) acrylic-based monomers, and (meth) acrylamide-based monomers, which are excellent in radical polymerization reactivity, and thus (meth). Acrylic monomers and (meth) acrylamide monomers are preferred. In addition, (meth) acrylic means acrylic or methacrylic.

Examples of vinyl-based monomers include styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, α-methylstyrene, o-ethylstyrene, m-ethylstyrene, p-ethylstyrene, and 2,4-dimethyl. Styrene, pn-butyl styrene, pt-butyl styrene, pn-hexyl styrene, pn-octyl styrene, pn-nonyl styrene, pn-decyl styrene, pn-dodecyl styrene , P-methoxystyrene, p-phenylstyrene, p-chlorostyrene, styrene-based monomers such as 3,4-dichlorostyrene and the like. The vinyl-based monomer may be used alone or in combination of two or more.

Examples of the (meth) acrylic monomer include methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, n-butyl (meth) acrylate, isobutyl (meth) acrylate, and sec-butyl (meth). ) Acrylate, n-hexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, n-octyl (meth) acrylate, isooctyl (meth) acrylate, n-nonyl (meth) acrylate, isononyl (meth) acrylate, n-decyl (Meta) acrylate, lauryl (meth) methacrylate, stearyl (meth) acrylate, benzyl (meth) acrylate, isobornyl (meth) acrylate, cyclohexyl (meth) acrylate, 3,5,5-trimethylcyclohexyl (meth) acrylate, phenyl ( Examples thereof include (meth) acrylates such as meta) acrylates, dicyclopentanyl (meth) acrylates, dicyclopentenyl (meth) acrylates and adamantyl (meth) acrylates, and (meth) acrylic acids, with (meth) acrylates being preferred. Alkyl (meth) acrylates are more preferred. The (meth) acrylic monomer may be used alone or in combination of two or more. The alkyl group of the alkyl (meth) acrylate preferably has 2 or more carbon atoms, and more preferably 4 or more carbon atoms. The alkyl group of the alkyl (meth) acrylate preferably has 12 or less carbon atoms, more preferably 10 or less carbon atoms, and more preferably 8 or less carbon atoms. When the alkyl group has 2 or more carbon atoms, the crosslinkable block copolymer has an appropriate melt viscosity, excellent coatability, and excellent thermal stability, and further, after cross-linking. It has excellent adhesive properties such as peeling resistance. When the number of carbon atoms of the alkyl group is 12 or less, the crosslinkable block copolymer has an appropriate melt viscosity, excellent coatability, excellent thermal stability, and further, after cross-linking. It has excellent adhesive properties such as peeling resistance.

Examples of the (meth) acrylamide-based monomer include N, N-dimethyl (meth) acrylamide, N, N-diethyl (meth) acrylamide, N-isopropyl (meth) acrylamide, N-phenyl (meth) acrylamide, and N-benzyl. (Meta) acrylamide, N-isobornyl (meth) acrylamide, N-cyclohexyl (meth) acrylamide, N-3,5,5-trimethylcyclohexyl (meth) acrylamide, N-dicyclopentanyl (meth) acrylamide, N-di Cyclopentenyl (meth) acrylamide, N-adamantyl (meth) acrylamide, N, N-diphenyl (meth) acrylamide and the like can be mentioned. The (meth) acrylamide-based monomer may be used alone or in combination of two or more.

The monomer constituting the polymer block B and the monomer constituting the polymer block A having no crosslinkability may be the same or different.

In the crosslinkable block copolymer, the total content of the polymer block A is preferably 5% by mass or more, more preferably 10% by mass or more, and particularly preferably 15% by mass or more. When the total content of the polymer block A is 5% by mass or more, the crosslinkable block copolymer has an appropriate melt viscosity and excellent coatability, and the crosslinkable block copolymer has excellent coatability. Has excellent peeling resistance after cross-linking.

In the crosslinkable block copolymer, the total content of the polymer block A is preferably 39% by mass or less, more preferably 30% by mass or less, and more preferably 25% by mass or less. When the total content of the polymer block A is 39% by mass or less, the crosslinkable block copolymer has an appropriate melt viscosity and excellent coatability, and the crosslinkable block copolymer has excellent coatability. Has excellent peeling resistance after cross-linking.

In the crosslinkable block copolymer, the content of the polymer block B is preferably 61% by mass or more, more preferably 70% by mass or more, and more preferably 75% by mass or more. When the total content of the polymer block B is 61% by mass or more, the crosslinkable block copolymer has an appropriate melt viscosity and excellent coatability, and the crosslinkable block copolymer has excellent coatability. Has excellent peeling resistance after cross-linking.

In the crosslinkable block copolymer, the content of the polymer block B is preferably 95% by mass or less, more preferably 90% by mass or less, and more preferably 85% by mass or less. When the total content of the polymer block B is 95% by mass or less, the crosslinkable block copolymer has an appropriate melt viscosity and excellent coatability, and the crosslinkable block copolymer has excellent coatability. Has excellent peeling resistance after cross-linking.

The molecular weight of the polymer constituting the polymer block B is preferably 5000 or more, more preferably 40,000 or more, and more preferably 50,000 or more. The molecular weight of the polymer constituting the polymer block B is preferably 400,000 or less, more preferably 240000 or less, and particularly preferably 150,000 or less. When the weight average molecular weight of the polymers constituting the polymer block B is 5000 or more, the peeling resistance of the crosslinkable block copolymer after cross-linking is improved. When the molecular weight of the polymer constituting the polymer block B is 400,000 or less, the crosslinkable block copolymer has an appropriate melt viscosity and has excellent coatability.

In the present invention, the molecular weight of the polymer constituting the polymer block B refers to a value calculated as follows. In the case of a crosslinkable block copolymer polymerized using a compound having one structure (for example, an exchange chain reaction site) that can activate living polymerization per molecule, the polymer constituting the polymer block B The molecular weight of is from the peak top molecular weight of the polymer block A-polymer block B partial polymer or the crosslinkable block copolymer which is an AB type diblock copolymer to the peak of the polymer block A partial polymer. The value obtained by subtracting the top molecular weight. In the case of a crosslinkable block copolymer polymerized using a compound having two structures (for example, exchange chain reaction sites) that can activate living polymerization per molecule, the polymer constituting the polymer block B The molecular weight of is the value obtained by subtracting the peak top molecular weight of the polymer block A partial polymer from the peak top molecular weight of the crosslinkable block copolymer.

In the crosslinkable block copolymer, the ratio of the molecular weight of the polymer block A to the molecular weight of the polymer block B (molecular weight of the polymer block A / molecular weight of the polymer block B) is preferably 0.03 or more. 05 or more is more preferable, and 0.08 or more is more preferable. In the crosslinkable block copolymer, the ratio of the molecular weight of the polymer block A to the molecular weight of the polymer block B (molecular weight of the polymer block A / molecular weight of the polymer block B) is preferably 0.32 or less, and is 0. 22 or less is more preferable, and 0.17 or less is particularly preferable. When the ratio of the molecular weight of the polymer block A to the molecular weight of the polymer block B is 0.03 or more, the peeling resistance of the crosslinkable block copolymer after cross-linking is improved. When the ratio of the molecular weight of the polymer block A to the molecular weight of the polymer block B is 0.32 or less, the crosslinkable block copolymer has an appropriate melt viscosity and has excellent coatability. When a plurality of polymer blocks A are contained in the crosslinkable block copolymer, the molecular weight of the polymer block A refers to the arithmetic mean value of the molecular weights of the plurality of polymer blocks A. When a plurality of polymer blocks B are contained in the crosslinkable block copolymer, the molecular weight of the polymer block B refers to the arithmetic mean value of the molecular weights of the plurality of polymer blocks B.

The weight average molecular weight (Mw) of the crosslinkable block copolymer is preferably 10,000 or more, more preferably 50,000 or more, more preferably 70,000 or more, and particularly preferably 80,000 or more. The weight average molecular weight (Mw) of the crosslinkable block copolymer is preferably 500,000 or less, more preferably 300,000 or less, more preferably 250,000 or less, and particularly preferably 200,000 or less. When the weight average molecular weight (Mw) is 10,000 or more, the peeling resistance of the crosslinkable block copolymer after cross-linking is improved. When the weight average molecular weight (Mw) is 500,000 or less, the crosslinkable block copolymer has an appropriate melt viscosity and has excellent coatability.

The dispersity (weight average molecular weight Mw / number average molecular weight Mn) of the crosslinkable block copolymer is preferably 3.0 or less, more preferably 2.5 or less, and particularly preferably 2.0 or less. When the dispersity is 3.0 or less, the peeling resistance of the crosslinkable block copolymer after cross-linking is improved.

The molecular weight, weight average molecular weight, and number average molecular weight of the polymers constituting the polymer block of the crosslinkable block copolymer are polystyrene-equivalent values measured by the GPC (gel permeation chromatography) method. .. Specifically, 0.01 g of the crosslinkable block copolymer is collected, the collected crosslinkable block copolymer is supplied to a test tube, and THF (tetrahexyl) is added to the test tube to add the crosslinkable block copolymer weight. The coalescence is diluted 500-fold and filtered to prepare a measurement sample.

Using this measurement sample, the molecular weight of the polymer constituting the polymer block of the crosslinkable block copolymer, and the weight average molecular weight Mw and the number average molecular weight Mn of the crosslinkable block copolymer are measured by the GPC method. can do.

The molecular weight of the polymer constituting the polymer block of the crosslinkable block copolymer, and the weight average molecular weight Mw and the number average molecular weight Mn of the crosslinkable block copolymer are determined by, for example, the following measuring apparatus and measurement conditions. Can be measured.
Measuring device Waters ACQUITY APC system Measuring conditions Column: Waters HSPgel (TM) HR MB-M
Mobile phase: Tetrahydrofuran used 0.5 mL / min
Detector: RI detector
Standard substance: polystyrene
SEC temperature: 40 ° C

In a crosslinkable block copolymer, when the attenuation curve obtained by the Solid echo method by ¹ H pulse NMR (20 MHz) at 40 ° C. is fitted with a two-component relaxation curve using the nonlinear least squares method, the shorter one (the first). The spin-spin relaxation time T ₂ (1) of one component) (hereinafter, may be simply referred to as “relaxation time T ₂ (1)”) is preferably 35 μs or more, more preferably 40 μs or more, and 42 μs or more. Is more preferable, and 60 μsec or more is more preferable. In a crosslinkable block copolymer, when the attenuation curve obtained by the Solid echo method by ¹ H pulse NMR (20 MHz) at 40 ° C. is fitted with a two-component relaxation curve using the nonlinear least squares method, the shorter one (the first). The spin-spin relaxation time T ₂ (1) of one component) (hereinafter, may be simply referred to as “relaxation time T ₂ (1)”) is preferably 85 μsec or less, more preferably 83 μsec or less, and 81 μsec or less. Is more preferable, and 75 μsec or less is more preferable. When the spin-spin relaxation time T ₂ (1) is 35 μsec or more, the crosslinkable block copolymer has an appropriate melt viscosity and has excellent coatability. When the spin-spin relaxation time T ₂ (1) is 85 μsec or less, the peeling resistance of the crosslinkable block copolymer after cross-linking is improved.

In the crosslinkable block copolymer, the relaxation time T ₂ (2) of the longer one (second component) of the relaxation times of the above two relaxation curves (hereinafter, simply referred to as "relaxation time T ₂ (2)"). ) Is preferably 500 μs or more, more preferably 600 μs or more. In the crosslinkable block copolymer, the relaxation time T ₂ (2) of the longer one (second component) of the relaxation times of the above two relaxation curves is preferably 1000 μs or less, more preferably 800 μs or less. When the spin-spin relaxation time T ₂ (2) is 500 μsec or more, the crosslinkable block copolymer has an appropriate melt viscosity and has excellent coatability. When the spin-spin relaxation time T ₂ (2) is 1000 μsec or less, the peeling resistance of the crosslinkable block copolymer after cross-linking is improved.

In a block copolymer obtained by cross-linking a crosslinkable block copolymer, the attenuation curve obtained by the Solid echo method by ¹ H pulse NMR (20 MHz) at 40 ° C. is relaxed by two components using the nonlinear least squares method. When curve-fitted, the shorter spin-spin relaxation time T ₂ (1) is 40 μsec or more, preferably 60 μsec or more. In a block copolymer obtained by cross-linking a crosslinkable block copolymer, the attenuation curve obtained by the Solid echo method by ¹ H pulse NMR (20 MHz) at 40 ° C. is relaxed by two components using the nonlinear least squares method. When curve-fitted, the shorter spin-spin relaxation time T ₂ (1) is 90 μsec or less, preferably 75 μsec or less. When the spin-spin relaxation time T ₂ (1) is 40 μsec or more, the crosslinkable block copolymer has an appropriate melt viscosity and has excellent coatability. When the spin-spin relaxation time T ₂ (1) is 90 μsec or less, the peeling resistance of the crosslinkable block copolymer after cross-linking is improved.

In a block copolymer obtained by cross-linking a crosslinkable block copolymer, the spin-spin relaxation time of the longer (second component) of the spin-spin relaxation times of the above two relaxation curves T ₂ (2). ) Is preferably 500 μs or more, and more preferably 600 μs or more. In a block copolymer obtained by cross-linking a crosslinkable block copolymer, the spin-spin relaxation time of the longer (second component) of the spin-spin relaxation times of the above two relaxation curves T ₂ (2). ) Is preferably 1000 μsec or less, and more preferably 800 μsec or less. When the relaxation time T ₂ (2) is 500 μsec or more, the crosslinkable block copolymer has an appropriate melt viscosity and has excellent coatability. When the relaxation time T ₂ (2) is 1000 μsec or less, the peeling resistance of the crosslinkable block copolymer after cross-linking is improved.

In the crosslinkable block copolymer before and after cross-linking, the rate of change of the relaxation time T ₂ (2) is preferably 10% or less, more preferably 6.5% or less, and particularly preferably 5% or less. When the rate of change of the relaxation time T ₂ (2) is 10% or less, the polymer block A of the crosslinkable block copolymer is more selectively crosslinked, and the peeling resistance of the crosslinkable block copolymer after cross-linking is achieved. Is improved.

The rate of change in the relaxation time T ₂ (2) of the crosslinkable block copolymer before and after cross-linking (hereinafter, may be simply referred to as “rate of change in T ₂ (2)”) is calculated based on the following formula. Value.
Rate of change (%) of T ₂ (2)
= 100 × (Spin-spin relaxation time of crosslinkable block copolymer (before cross-linking) T ₂ (2) -Spin-spin relaxation time of block copolymer after cross-linking of cross-linkable block copolymer T ₂ (2)) / Cross-linking Spin-spin relaxation time of sex block copolymer (before cross-linking) T ₂ (2)

Further, in the crosslinkable block copolymer, the spin-spin of the two-component transition curve obtained by fitting the decay curve obtained by the Solid echo method in ¹ H pulse NMR (20 MHz) at 40 ° C. as described later. Of the relaxation times, the component ratio A ₁ of the transition curve having the shorter spin-spin relaxation time T ₂ (1) is preferably 6% or more, more preferably 10% or more, and 13% or more. Is more preferable. Spin-spin relaxation time of the two-component transition curve obtained by fitting the decay curve obtained by the Solid echo method in ¹ H pulse NMR (20 MHz) at 40 ° C. in the crosslinkable block copolymer as described later. Of these, the component ratio A ₁ of the transition curve having the shorter (first component) spin-spin relaxation time T ₂ (1) is preferably 30% or less, preferably 29% or less, and more preferably 28% or less. .. When the component ratio A ₁ is 6% or more, the peeling resistance of the crosslinkable block copolymer after cross-linking is improved. When the component ratio A ₁ is 30% or less, the crosslinkable block copolymer has an appropriate melt viscosity and has excellent coatability.

Spin-spin relaxation time of the two-component transition curve obtained by fitting the decay curve obtained by the Solid echo method in ¹ H pulse NMR (20 MHz) at 40 ° C. in the crosslinkable block copolymer as described later. Of these, the component ratio A ₂ of the transition curve having the longer (second component) spin-spin relaxation time T ₂ (2) is preferably 70% or more, more preferably 71% or more, and particularly 72% or more. preferable. Spin-spin relaxation time of the two-component transition curve obtained by fitting the decay curve obtained by the Solid echo method in ¹ H pulse NMR (20 MHz) at 40 ° C. in the crosslinkable block copolymer as described later. Of these, the component ratio A ₂ of the transition curve having the longer (second component) spin-spin relaxation time T ₂ (2) is preferably 94% or less, more preferably 90% or less, and particularly 87% or less. preferable. When the component ratio A ₂ is 70% or more, the crosslinkable block copolymer has an appropriate melt viscosity and has excellent coatability. When the component ratio A ₂ is 94% or less, the peeling resistance of the crosslinkable block copolymer after cross-linking is improved.

Further, in a block copolymer obtained by cross-linking a crosslinkable block copolymer, it is obtained by fitting the attenuation curve obtained by the Solid echo method in ¹ H pulse NMR (20 MHz) at 40 ° C. as described later. Of the spin-spin relaxation times of the _two- component relaxation curves, the component ratio A ₁ of the relaxation curve having the shorter (first component) spin-spin relaxation time T ₂ (1) is 10% or more. 12% or more is preferable, and 15% or more is more preferable. In a block copolymer obtained by cross-linking a crosslinkable block copolymer, the decay curve obtained by the Solid echo method in ¹ H pulse NMR (20 MHz) at 40 ° C. was fitted by fitting as described below. Of the spin-spin relaxation times of the component relaxation curves, the component ratio A ₁ of the relaxation curve having the shorter (first component) spin-spin relaxation time T ₂ (1) is 35% or less, 33%. The following is preferable, and 30% or less is more preferable. When the component ratio A ₁ is 10% or more, the peeling resistance of the crosslinkable block copolymer after cross-linking is improved. When the component ratio A ₁ is 35% or less, the crosslinkable block copolymer has an appropriate melt viscosity and has excellent coatability.

In a block copolymer obtained by cross-linking a crosslinkable block copolymer, the decay curve obtained by the Solid echo method in ¹ H pulse NMR (20 MHz) at 40 ° C. was fitted by fitting as described below. Of the spin-spin relaxation times of the component relaxation curves, the component ratio A ₂ of the relaxation curve having the longer (second component) spin-spin relaxation time T ₂ (2) is preferably 65% or more, preferably 67%. The above is more preferable, and 70% or more is particularly preferable. In a block copolymer obtained by cross-linking a crosslinkable block copolymer, the decay curve obtained by the Solid echo method in ¹ H pulse NMR (20 MHz) at 40 ° C. was fitted by fitting as described below. Of the spin-spin relaxation times of the component relaxation curves, the component ratio A ₂ of the relaxation curve having the longer (second component) spin-spin relaxation time T ₂ (2) is preferably 90% or less, preferably 88%. The following is more preferable, and 85% or less is particularly preferable. When the component ratio A ₂ is 65% or more, the crosslinkable block copolymer has an appropriate melt viscosity and has excellent coatability. When the component ratio A ₂ is 90% or less, the peeling resistance of the crosslinkable block copolymer after cross-linking is improved.

Block copolymer obtained by crosslinking a crosslinkable block copolymer, relaxation time T ₂ and (1), and the component ratio A ₁ of the relaxation curve with the relaxation time T ₂ (1) satisfies the above range As a result, the hard component and the soft component are present in a predetermined ratio, and the block copolymer obtained by cross-linking the crosslinkable block copolymer exhibits a good layer-separated structure and the above-mentioned hard component. Since the block copolymer has an appropriate hardness, the block copolymer obtained by cross-linking the cross-linkable block copolymer exhibits excellent peeling resistance, and further, the cross-linkable block copolymer is excellent. Has coating properties.

The crosslinkable block copolymer contains a polymer block A and a polymer B, preferably an ABA type triblock copolymer, and the hard component is a glass of the polymer blocks A and B. The soft component is mainly composed of the polymer blocks having a low glass transition temperature among the polymer blocks A and B, while the soft components are mainly composed of the polymer blocks having a high transition temperature.

The hard component is mainly composed of the polymer block A, the soft component is mainly composed of the polymer block B, and the crosslinked structure is positively introduced into the polymer block A to form a crosslinkable block copolymer. It is possible to satisfactorily form a layer-separated structure due to the polar difference between the polymer blocks A and B of the block copolymer obtained by cross-linking the cross-linkable block copolymer while imparting appropriate hardness. , It is preferable that the block copolymer obtained by cross-linking the cross-linkable block copolymer can be imparted with excellent peeling resistance.

As the non-crosslinkable monomer constituting the polymer block A, a monomer having a saturated aliphatic ring structure (preferably isobornyl (meth) acrylate, cyclohexyl (meth) acrylate, t-butylcyclohexyl (meth) acrylate, 3, 5,5-trimethylcyclohexyl (meth) acrylate, dicyclopentanyl (meth) acrylate and adamantyl (meth) acrylate, more preferably isobornyl (meth) acrylate, cyclohexyl (meth) acrylate and 4-t-butylcyclohexyl (meth). ) By containing (acrylate), the hard component can be composed of the polymer block A in a high ratio, and the block copolymer obtained by cross-linking the crosslinkable block copolymer has more excellent peeling resistance. Have.

A method for measuring the attenuation curve of a crosslinkable block copolymer at 40 ° C. by ¹ H pulse NMR (20 MHz), a method for fitting the obtained attenuation curve to a two-component relaxation curve using a nonlinear least squares method, and an relaxation curve. The method of determining the spin-spin relaxation time and the component ratio based on the above will be described.

^{1 Use an} H-pulse NMR measuring device. ^{1 The} H-pulse NMR measuring device irradiates all protons existing in the measurement sample with pulsed radio waves at a low frequency (several tens of MHz) by a permanent magnet to cause nuclear magnetic resonance, and the response (spin-spin relaxation time). ) Is a measuring device to observe.

Weigh about 0.2 g each of the crosslinkable block copolymer before cross-linking or the block copolymer after cross-linking on the bottom of the NMR tube, set it in a ¹ H pulse NMR measuring device, and measure under the following conditions. To obtain the decay curve. As the ¹ H pulse NMR measuring device, a measuring device commercially available from Bruker under the trade name “minispec mq20” can be used.

Frequency: 20MHz
Measurement temperature: 40 ° C
Measurement conditions: Solid-echo method scans: 64
Recycle delay: 1s
Detection Mode: Magnitude
acquisition scales: 3ms

The block copolymer after cross-linking is produced in the following manner. A crosslinkable block copolymer before cross-linking is coated on the release-treated polyethylene terephthalate sheet so as to have a thickness of 20 μm. Next, the crosslinkable block copolymer is crosslinked so that the gel fraction is 50 to 90% by mass to prepare a crosslinked block copolymer.

For example, the crosslinkable block copolymer is irradiated with ultraviolet rays under the conditions of a UV-C irradiation intensity of about 48 mW / cm ² and a UV-C integrated light amount of 100 mJ / cm ² using an ultraviolet irradiation device, and the crosslinkable block co-weight. The coalescence is crosslinked to produce a crosslinked block copolymer. As the ultraviolet irradiation device, for example, an ultraviolet irradiation device commercially available from Heleus (formerly Fusion UV Systems) under the trade name "Light Hammer 6" (using an H bulb) can be used. As the illuminometer, for example, an illuminometer commercially available from EIT Instrument Markets under the trade name "UV Power Pack II" can be used.

Next, the analysis software is used to decompose the decay curve of the pre-crosslinkable block copolymer or the post-crosslink block copolymer measured as described above into a two-component relaxation curve. The Weibull coefficient is set to 1 (exponential function) for both transition curves, and fitting is performed using the nonlinear least squares method. That is, the spin-spin relaxation time T ₂ and the component ratio A in the following formula are calculated. At that time, it is confirmed that the [err] of the [SSR / err] is 0 or 1 and that the data after the two-component fitting is sufficiently close to the measured attenuation curve. In addition, "^" means a power.
f (t) = A ₁ × exp {-1 / W (1) (t / T ₂ (1)) ^ W (1)} + A ₂ × exp {-1 / W (2) (t / T ₂ (t / T ₂ ) 2)) ^ W (2)}

The shorter spin-spin relaxation time of the spin-spin relaxation time is defined as the spin-spin relaxation time T ₂ (1), and the longer spin-spin relaxation time is defined as the spin-spin relaxation time T ₂ (2). Let A _{1 be} the component ratio of the transition curve having the spin-spin relaxation time T ₂ (1), and let A _{2 be} the component ratio of the transition curve having the spin-spin relaxation time T ₂ (2). Let W (1) and W (2) be the Weibull coefficients (both 1) of each transition curve. As the analysis software, analysis software commercially available from Bruker under the trade name "TD-NMR Analyzer" can be used.

The gel fraction of the block copolymer after cross-linking refers to the value measured according to the following procedure. 0.2 g of the crosslinked block copolymer is supplied to a glass bottle. 30 g of tetrahydrofuran was supplied to a glass bottle and left at room temperature for 24 hours to swell the block copolymer after cross-linking.

The swollen block copolymer after cross-linking was filtered through a 200-mesh wire mesh, and the block copolymer after cross-linking was dried together with the wire mesh in a constant temperature bath heated to 80 ° C. The mass Yg of the block copolymer after cross-linking after drying is measured, and the gel fraction is calculated according to the following procedure.
Gel fraction (mass%) = 100 x Y / 0.2

In a crosslinkable block copolymer and a block copolymer after cross-linking thereof, the higher the glass transition temperature of the monomer constituting the polymer block that mainly forms a hard component, the shorter the spin-spin relaxation time T ₂ . can do. The lower the glass transition temperature of the monomer constituting the polymer block that mainly forms the hard component, the longer the spin-spin relaxation time T ₂ can be. The spin-spin relaxation time T ₂ can be shortened as the glass transition temperature of the monomer constituting the polymer block that mainly forms the soft component is increased. The lower the glass transition temperature of the monomer constituting the polymer block that mainly forms the soft component, the longer the spin-spin relaxation time T ₂ can be.

In the crosslinkable block copolymer and the block copolymer after cross-linking thereof, the component ratio A ₁ can be increased as the content of the polymer block mainly forming a hard component is increased. Enough to increase the content of the polymer block mainly formed a soft component, it is possible to lower the component ratio A _1.

In the crosslinkable block copolymer, the content of the non-crosslinkable monomer in the polymer block that mainly forms a hard component is preferably 10.0% by mass or more, more preferably 14.0% by mass or more, and 16. More preferably, it is 0% by mass or more. In the crosslinkable block copolymer, the content of the non-crosslinkable monomer in the polymer block that mainly forms a hard component is preferably 29.6% by mass or less, more preferably 25.6% by mass or less, and 23. More preferably, it is 6% by mass or less. When the content of the non-crosslinkable monomer in the polymer block that mainly forms a hard component is 10.0% by mass or more, the crosslinkable block copolymer has improved peeling resistance after cross-linking. When the content of the non-crosslinkable monomer in the polymer block mainly forming the hard component is 29.6% by mass or less, the crosslinkable block copolymer has an appropriate melt viscosity and is excellently coated. Has sex.

In the crosslinkable block copolymer, the content of the non-crosslinkable monomer in the polymer block that mainly forms a soft component is preferably 70.1% by mass or more, more preferably 75.0% by mass or more, 76. More preferably, it is 0% by mass or more. In the crosslinkable block copolymer, the content of the non-crosslinkable monomer in the polymer block that mainly forms a soft component is preferably 89.9% by mass or less, more preferably 85.0% by mass or less, 84. More preferably, it is 0% by mass or less. When the content of the non-crosslinkable monomer in the polymer block that mainly forms the soft component is 70.1% by mass or more, the crosslinkable block copolymer has an appropriate melt viscosity and is excellently coated. Has sex. When the content of the non-crosslinkable monomer in the polymer block that mainly forms the soft component is 89.9% by mass or less, the crosslinkable block copolymer has improved peeling resistance after cross-linking.

Next, a method for producing a crosslinkable block copolymer will be described. The crosslinkable block copolymer can be produced by using a general-purpose polymerization method, but it is preferably produced by using living polymerization.

Examples of the living radical polymerization include living radical polymerization, living cationic polymerization, and living anionic polymerization, but living radical polymerization is preferable from the viewpoint of high versatility and safety of the polymerization reaction.

Examples of the living radical polymerization method include iniferter polymerization, nitroxide-mediated polymerization (NMP), atom transfer radical addition polymerization using a transition metal catalyst (ATRP), reversible chain transfer polymerization using a dithioester compound (RAFT), and an organic tellurium compound. Examples thereof include polymerization (TERP), reversible transfer catalyst polymerization (RTC) catalyzed by an organic compound, and reversible coordination-mediated polymerization (RCMP).

In particular, reversible chain transfer polymerization (RAFT) has (1) high monomer versatility, (2) does not cause an extreme decrease in reactivity with oxygen and light, and (3) at extremely low or high temperatures. Since the reaction proceeds without it, it can be carried out in a simple polymerization reaction environment and has high productivity, (4) no toxic substances such as metals and halogens are used, and (5) a crosslinkable block having a sufficient molecular weight. It is preferable because a copolymer can be produced.

The dithioester compound used for carrying out reversible chain transfer polymerization (RAFT) is not particularly limited as long as it is a dithioester compound having exchange chain reactivity, for example, a dithiobenzoate compound, a trithiocarbonate compound, and the like. Examples thereof include dithiocarbamate compounds and xanthate compounds, and trithiocarbonate compounds are preferable.

The trithiocarbonate compound is not particularly limited, and is, for example, 2-[(dodecylsulfanylthiocarbonyl) sulfanyl] propanoic acid, 4-{[(2-carboxyethyl) sulfanylthiocarbonyl] sulfanyl} propanoic acid, 4-cyano. A trithiocarbonate compound having only one exchange chain reaction site such as -4-[(dodecylsulfanylthiocarbonyl) sulfanyl] pentanic acid, 4-[(2-carboxyethylsulfanylthiocarbonyl) sulfanyl] -4-cyanopentanoic acid. , S, S-dibenzyltrithiocarbonate, bis {4- [ethyl- (2-hydroxyethyl) carbamoyl] benzyl} trithiocarbonate, and other trithiocarbonate compounds having two exchange chain reaction sites. A trithiocarbonate compound having only one chain reaction site is preferable, and 2-[(dodecylsulfanylthiocarbonyl) sulfanyl] propanoic acid is more preferable.

In the crosslinkable block copolymer produced by using the trithiocarbonate compound, the introduction position of the trithiocarbonate compound residue in the crosslinkable block copolymer is different due to the chemical structure of the trithiocarbonate compound. When the trithiocarbonate compound has only one exchange chain reaction site, the trithiocarbonate compound residue is introduced at the end of the polymer block constituting the crosslinkable block copolymer. On the other hand, when the trithiocarbonate compound has two exchange chain reaction sites, the trithiocarbonate compound residue is introduced into the polymer block constituting the crosslinkable block copolymer. Then, in the crosslinkable block copolymer produced by reversible chain transfer polymerization (RAFT) using a trithiocarbonate compound having only one exchange chain reaction site, the trithiocarbonate compound residue is decomposed by heat or light. Even so, since the crosslinkable block copolymer structure itself is not decomposed, it is further excellent in thermal stability and ultraviolet crosslink reactivity.

As described above, the crosslinkable block copolymer is preferably produced by reversible chain transfer polymerization (RAFT) with a dithioester compound. Examples of the polymerization form of reversible chain transfer polymerization (RAFT) include bulk polymerization, solution polymerization, suspension polymerization, emulsion polymerization and the like, and solution polymerization is preferable. When the crosslinkable block copolymer is produced by solution polymerization, it is necessary to detreat the solvent in the system in order to use the crosslinkable block copolymer as a hot melt adhesive.

Multi-step polymerization is performed to produce a crosslinkable block copolymer. For example, when reversible chain transfer polymerization (RAFT) is performed using a dithioester compound having only one exchange chain reaction site, first, the monomer constituting the polymer block A is used as a dithioester compound (dithioester). It is sufficiently polymerized (in the presence of the compound) to obtain a polymer block A partial polymer (first stage polymerization). Next, the monomer constituting the polymer block B is supplied into the polymerization reaction system and sufficiently polymerized to obtain a polymer block A-polymer block B partial polymer (second-stage polymerization). Further, a monomer constituting the polymer block A is supplied into the polymerization reaction system and sufficiently polymerized, and the polymer block A is bonded to both ends of the polymer block B to form an ABA type triblock. A crosslinkable block copolymer which is a copolymer can be obtained. In the case of producing a crosslinkable block copolymer which is an AB type diblock copolymer, the above-mentioned first-step polymerization and second-step polymerization may be carried out.

Further, when reversible chain transfer polymerization (RAFT) is performed using a dithioester compound having two exchange chain reaction sites, the monomer constituting the polymer block A is used as a dithioester compound (presence of the dithioester compound). Sufficiently polymerize (below) to give the polymer block A partial polymer (first step polymerization). Next, the monomer constituting the polymer block B is supplied into the polymerization reaction system and polymerized (second-stage polymerization) to form the polymer block B in the middle portion of the polymer block A partial polymer, and A A crosslinkable block copolymer, which is a −BA type triblock copolymer, can be obtained.

The content of the non-crosslinkable monomer in the monomer used as a raw material for producing the polymer block A is 60% by mass or more because the peeling resistance of the crosslinkable block copolymer after cross-linking is improved. Preferably, 90% by mass or more is more preferable, 95% by mass or more is more preferable, and 98% by mass or more is particularly preferable. The content of the non-crosslinkable monomer in the monomer used as a raw material for producing the polymer block A is 99.9% by mass because the peeling resistance of the crosslinkable block copolymer after cross-linking is improved. The following is preferable, 99.8% by mass or less is more preferable, and 99.7% by mass or less is particularly preferable.

The content of the crosslinkable monomer in the monomer used as a raw material for producing the polymer block A is preferably 40% by mass or less because the peeling resistance of the crosslinkable block copolymer after cross-linking is improved. It is more preferably 10% by mass or less, more preferably 5% by mass or less, and particularly preferably 2% by mass or less. The content of the crosslinkable monomer in the monomer used as the raw material for producing the polymer block A is 0.1% by mass or more because the peeling resistance of the crosslinkable block copolymer after crosslinkation is improved. Is preferable, 0.2% by mass or more is more preferable, and 0.3% by mass or more is particularly preferable.

Crosslinkable block copolymers produced using dithioester compounds may have a coloration derived from their chemical structure and a unique odor derived from sulfur atoms. For the purpose of reducing or removing such coloring and odor, reduction or removal treatment of dithioester compound residues in the crosslinkable block copolymer, and residual dithioester mixed in the crosslinkable block copolymer. It is preferable to carry out a reduction or removal treatment of the compound. Treatment methods for reducing or removing dithioester compound residues or residual dithioester compounds include, for example, treatment with heat, treatment with ultraviolet rays, treatment with excess radical initiator, treatment with a nucleophilic reagent or reducing agent, and treatment with an oxidizing agent. , Treatment with a metal catalyst, treatment with a hetero Diels-Alder reaction with a diene compound, and the like. Even if the dithioester compound residue or the residual dithioester compound is reduced or removed by the above treatment, there is no change in the action and effect of the crosslinkable block copolymer.

The crosslinkable block copolymer can be suitably used as a hot melt adhesive by adding an additive such as a tackifier and a photoacid generator, if necessary. The hot melt adhesive containing the crosslinkable block copolymer has an appropriate melt viscosity, and therefore has excellent coatability.

The crosslinkable block copolymer is a monomer unit having crosslinkability contained in the polymer block A by being coated on an adherend and then subjected to a crosslinking treatment on the crosslinkable block copolymer. The crosslinkable group forms a crosslinked structure, and the crosslinked structure is introduced into the polymer block A. The block copolymer in which the crosslinked structure is introduced exhibits excellent adhesiveness such as peeling resistance.

Even if the hot melt adhesive contains additives such as a tackifier, an ultraviolet polymerization initiator, a plasticizer, an antioxidant, a colorant, a flame retardant, and an antistatic agent within a range that does not impair its physical properties. Good.

The crosslinkable block copolymer of the present invention has a low viscosity and is excellent in coatability. The block copolymer obtained by cross-linking the cross-linkable block copolymer of the present invention is excellent in adhesive physical properties, particularly peeling resistance.

It is a graph which showed the attenuation curve of the crosslinkable block copolymer obtained in Example 1, and the relaxation curve obtained by fitting this attenuation curve into a two-component relaxation curve.

Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited thereto.

(Examples 1 to 12, Comparative Examples 1 to 3 and 6)
In a separable flask equipped with a stirrer, a cooling tube, a thermometer and a nitrogen gas inlet, isobornyl acrylate, cyclohexyl acrylate, 4-t-butylcyclohexyl acrylate and n-butyl acrylate as non-crosslinkable monomers and a crosslinkable monomer. 4-acryloyloxybenzophenone, 4- [2- (acryloyloxy) ethoxy] benzophenone and 4-hydroxybutyl acrylate glycidyl ether, and 2-[(dodecylsulfanylthiocarbonyl) sulfanyl] propanoic acid as a trithiocarbonate compound, and a solvent. And ethyl acetate was supplied in the amounts shown in Tables 1 and 2, respectively, and stirred to prepare a reaction solution.

After replacing the inside of the separable flask with nitrogen gas, the reaction solution was maintained at 60 ° C. using a water bath. Next, reversible chain transfer polymerization (RAFT) was started by supplying 2,2'-azobis (isobutyronitrile) as a polymerization initiator to the reaction solution in the separable flask in the amounts shown in Tables 1 and 2. did. The reaction solution was kept at 60 ° C. for 6 hours to obtain a polymer block A partial polymer. The peak top molecular weight and weight average molecular weight of the polymer block A partial polymer are shown in Tables 1 and 2.

In the reaction solution containing the polymer block A partial polymer, n-butyl acrylate and 2-ethylhexyl acrylate as the non-crosslinkable monomer, 4-acryloyloxybenzophenone as the cross-linkable monomer, and ethyl acetate as the solvent were added to Table 1 and respectively. The compounding amounts shown in 2 were supplied. The reaction solution was kept at 60 ° C. for 6 hours to perform reversible chain transfer polymerization (RAFT) to obtain a polymer block A-polymer block B partial polymer. The peak top molecular weight and weight average molecular weight of the polymer block A-polymer block B partial polymer are shown in Tables 1 and 2.

Polymer block A-polymer block B Partial polymer-containing reaction solution contains isobornyl acrylate, cyclohexyl acrylate, 4-t-butylcyclohexyl acrylate and n-butyl acrylate as non-crosslinkable monomers and 4 as cross-linkable monomers. -Acryloyloxybenzophenone, 4- [2- (acryloyloxy) ethoxy] benzophenone and 4-hydroxybutyl acrylate glycidyl ether, and ethyl acetate as a solvent were supplied in the amounts shown in Tables 1 and 2, respectively. The reaction mixture was kept at 60 ° C. for 6 hours to perform reversible chain transfer polymerization (RAFT), and then ethyl acetate was removed to obtain a crosslinkable block copolymer. The crosslinkable block copolymer was an ABA type triblock copolymer in which the polymer block A was bonded to both ends of the polymer block B. The peak top molecular weight, weight average molecular weight, and dispersity of the crosslinkable block copolymer are shown in Tables 1 and 2. The contents of polymer blocks A and B in the crosslinkable block copolymer are shown in Tables 1 and 2. Tables 1 and 2 show the total content of the polymer block A and the content of the polymer block B in the crosslinkable block copolymer.

(Comparative Examples 4 and 5)
In a separable flask equipped with a stirrer, a cooling tube, a thermometer and a nitrogen gas inlet, n-butyl acrylate, isobornyl acrylate, cyclohexyl acrylate and 4-t-butylcyclohexyl acrylate as non-crosslinkable monomers and crosslinkable monomers 4-Acryloyloxybenzophenone as a trithiocarbonate compound, 2-[(dodecylsulfanylthiocarbonyl) sulfanyl] propanoic acid as a trithiocarbonate compound, and ethyl acetate as a solvent were supplied in the amounts shown in Table 3 and stirred for reaction. A liquid was prepared.

After replacing the inside of the separable flask with nitrogen gas, the reaction solution was maintained at 60 ° C. using a water bath. Next, reversible chain transfer polymerization (RAFT) was started by supplying 2,2'-azobis (isobutyronitrile) as a polymerization initiator to the reaction solution in the separable flask in the amounts shown in Table 3. The reaction mixture was kept at 60 ° C. for 6 hours to perform reversible chain transfer polymerization (RAFT), and then ethyl acetate was removed to obtain a crosslinkable random copolymer. Table 3 shows the peak top molecular weight, weight average molecular weight, and dispersity of the crosslinkable random copolymer.

(Making hot melt adhesive)
The crosslinkable block copolymers of Examples 1 and 4 to 12, Comparative Examples 1 to 6 and 6 and the crosslinkable random copolymers of Comparative Examples 4 and 5 were used as hot melt adhesives without any treatment. ..

To 100 parts by mass of the crosslinkable block copolymer of Example 2, 10 parts by mass of a rosin ester-based tack fire (trade name "Foral 85-E" manufactured by Eastman Chemical Co., Ltd.) was added as a tackifier and uniformly at 130 ° C. Mixing gave a hot melt adhesive.

2 parts by mass of a triarylsulfonium salt-based photoacid generator (trade name "CPI-200K" manufactured by San-Apro) as a photoacid generator (UV cation generator) is added to 100 parts by mass of the crosslinkable block copolymer of Example 3. It was added and mixed uniformly at 130 ° C. to obtain a hot melt adhesive.

The crosslinkable block copolymers obtained in Examples and Comparative Examples, the block copolymers crosslinked with the crosslinkable block copolymers, the crosslinkable random copolymers, and the crosslinkable random copolymers were crosslinked. For the random copolymer, the decay curve was measured as described above, and based on this decay curve, spin-spin relaxation times T ₂ (1) and T ₂ (2), and component ratios A ₁ and A ₂ were obtained. .. The rate of change (%) of relaxation time T ₂ (2) was also calculated. The gel fractions of the block copolymer and the random copolymer after cross-linking are shown in Tables 3 to 5.

A graph showing the attenuation curve of the crosslinkable block copolymer obtained in Example 1 and the relaxation curve obtained by fitting the attenuation curve to the two-component relaxation curve is shown in FIG. The vertical axis is the "signal intensity ratio when the maximum intensity of the attenuation curve is 1." The component ratio A ₁ of the transition curve can be read from the value of the Y-axis intercept of the transition curve having the spin-spin relaxation time T ₂ (1). The component ratio A ₂ of the transition curve can be read from the value of the Y-axis intercept of the transition curve having the spin-spin relaxation time T ₂ (2).

The coatability and adhesiveness of the crosslinkable block copolymers and the crosslinkable random copolymers obtained in Examples and Comparative Examples were measured as follows.

(Paintability)
The measuring device shown below was prepared. 13 g of the hot melt adhesive was collected and put into an aluminum cylinder to be mounted in the Thermosel. The temperature was set to 130 ° C. to melt the hot melt adhesive. The melt viscosity was measured over 30 minutes using the spindle 4-29. The numerical value after the measurement for 30 minutes was read and used as the melt viscosity at 130 ° C.
Measuring instrument: DV-E Viscometer (manufactured by Brookfield)
Thermosel (manufactured by Brookfield)

Based on the obtained melt viscosity at 130 ° C., it was evaluated according to the following criteria.
A: The melt viscosity was less than 70 Pa · s.
B: The melt viscosity was 70 Pa · s or more and less than 150 Pa · s.
C: The melt viscosity was 150 Pa · s or more.

(Peeling resistance: constant load holding force vs. SUS)
A hot melt adhesive was applied onto a polyethylene terephthalate (PET) film to a thickness of 20 μm. Next, using an ultraviolet irradiation device (trade name "Light Hammer 6" (using H valve) manufactured by Heleus (formerly Fusion UV Systems)), UV-C irradiation intensity: about 48 mW / cm ² , UV-C integrated light amount: The hot melt adhesive was irradiated with ultraviolet rays (UV-C) at 60 mJ / cm ² to cure the hot melt adhesive. A test piece was prepared by laminating and integrating an adhesive layer having a thickness of 20 μm on a polyethylene terephthalate film.

A test piece was prepared by cutting the test film into a width of 15 mm and a length of 150 mm. On the other hand, a SUS plate was prepared, and the surface of the SUS plate was polished with # 240 water-resistant sandpaper and then wiped with a mixed solvent of hexane and acetone to degreas.

A test piece was attached to the surface of the SUS plate with an adhesive layer to a length of 75 mm from the end of the test piece, and then a 2 kg hand roller was reciprocated on the test piece. After a curing time of 30 minutes, the test piece was installed so that the bonding surface faced downward. A weight of 150 g was hung on the end of the test piece not attached to the SUS plate, and the measurement was started with a load applied so that the test piece was peeled off at an angle of 90 degrees with respect to the SUS surface. The measurement was completed when the bonded 75 mm was completely peeled off and the test piece fell, or when one hour had passed from the start of the measurement.

When 1 hour had passed from the start of the measurement, the distance (peeling distance) at which the test piece was peeled from the SUS plate was measured. When the test piece fell from the SUS plate within 1 hour, the peeling distance at 1 hour after the start of the test was proportionally calculated based on the time required for the test piece to fall from the start of the test. The shorter the peeling distance, the better the peeling resistance.

(Peeling resistance: constant load holding force vs. PET)
An amorphous polyethylene terephthalate (A-PET) plate was prepared, and the surface of the A-PET plate was wiped with a mixed solvent of hexane and acetone to degreas. The peeling distance was measured in the same manner as described above except that this A-PET plate was used instead of the SUS plate and the mass of the weight was 100 g.

According to the present invention, it is possible to provide a crosslinkable block copolymer having a low melt viscosity, excellent coatability, and excellent adhesive properties, particularly peeling resistance, and a hot melt adhesive using the same.

(Cross-reference of related applications)
This application claims priority based on Japanese Patent Application No. 2019-5256 filed on January 16, 2019 and Japanese Patent Application No. 2019-96487 filed on May 23, 2019. However, the disclosure of this application is incorporated herein by reference in its entirety.

C Relaxation curve with the shorter (first component) spin-spin relaxation time T ₂ (1) of the relaxation curves obtained by fitting the two-component relaxation curve using the non-linear least-square method. Of the relaxation curves obtained by fitting a two-component relaxation curve using the non-linear least-square method, the relaxation curve E decay curve having the longer (second component) spin-spin relaxation time T ₂ (2).

Claims (6)

Polymer block A containing a crosslinkable monomer unit and
It has a polymer block B and
After cross-linking, the shorter spin-spin relaxation when the attenuation curve obtained by the Solid echo method in ¹ H pulse NMR (20 MHz) at 40 ° C. is fitted to a two-component relaxation curve using the nonlinear least squares method. A crosslinkable block characterized in that the time T ₂ (1) is 40 to 90 μsec and the component ratio A _{1 of the} relaxation curve having the spin-spin relaxation time T ₂ (1) is 10 to 35%. Polymer. The crosslinkable block copolymer according to claim 1, wherein the polymer block A is bonded to both ends of the polymer block B to form an ABA type crosslinkable block copolymer. The crosslinkable block copolymer according to claim 1 or 2, wherein the polymer block A contains a monomer unit having a saturated aliphatic ring structure. The monomer unit having a saturated aliphatic ring structure is at least one (meth) selected from the group consisting of isobornyl (meth) acrylate units, cyclohexyl (meth) acrylate units and 4-t-butylcyclohexyl (meth) acrylate units. The crosslinkable block copolymer according to claim 3, which comprises an acrylate unit. The crosslinkable block copolymer according to any one of claims 1 to 4, wherein the crosslinkable monomer unit contains a radiation crosslinkable monomer unit. A hot melt adhesive comprising the crosslinkable block copolymer according to any one of claims 1 to 5.

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