JP6420062B2 - Method for producing pressure-sensitive adhesive and adhesive - Google Patents

Description

The present invention relates to a pressure-sensitive adhesive and a method for producing an adhesive .

Cyanoacrylate-based instant adhesives and epoxy-based adhesives are widely known as general adhesives.
These adhesives are synthesized mainly from fossil fuel-derived raw materials, and resource depletion has become a problem in recent years. For this reason, a polymer composition using biomass abundant in nature has been studied.

The present inventors are also advancing various studies on bioplastic adhesives having both biodegradability, high heat resistance and high adhesiveness.
Among these, a copolymer obtained by subjecting a monomer constituting hydrocaffeic acid or a derivative thereof to a ester having a carboxyl group and a hydroxyl group capable of ester linkage in a solvent-free transesterification reaction under an esterification catalyst is a hot melt type. In the shear peeling test using glass, carbon, and iron, the adhesive strength when used in the above shows a value that surpasses the epoxy resin that is said to be the strongest industrial adhesive (see Patent Document 1).
On the other hand, the adhesive is used in a wide range of fields such as an adhesive tape, a protective film, and a semiconductor process, and rubber, acrylic resin, and the like are used as the base resin.
As for adhesives, as in the case of adhesives, studies on polymer compositions using biomass abundant in nature are in progress.
For example, pressure-sensitive adhesives using epoxidized soybean oil derived from plants as a main raw material have been studied (see Patent Document 2).

International Publication Number W02012 / 102174 JP2014-58629A

Custom-made osteosynthesis material development guidelines 2010, November 2010, Ministry of Economy, Trade and Industry

It is an object of the present invention to provide a pressure-sensitive adhesive and a method for producing the adhesive, which can easily produce an adhesive and a pressure-sensitive adhesive using raw materials having a single composition depending on polymerization conditions.

The production method of the pressure-sensitive adhesive and adhesive according to the present invention comprises a polymerization raw material in which a monomer comprising the following formula (1) and a monomer comprising the following formula (4) are blended at a blending ratio of 10:90 to 90:10, By changing the heating time at a temperature of 100 to 300 ° C. and performing ester copolymerization, an adhesive having a molecular weight of 7,000 to 8,500 g / mol and a molecular weight of 30,000 to 60, It is characterized in that an adhesive of 000 g / mol is prepared separately .

In the method for producing a pressure-sensitive adhesive and an adhesive according to the present invention, since two predetermined monomers are used as a polymerization raw material, the adhesive and the pressure-sensitive adhesive are adjusted using a single composition of the raw material by adjusting conditions such as polymerization time. Agents can be made easily.

FIG. 1 is a diagram showing an example of a reaction scheme for copolymerizing 3- (3-hydroxyphenyl) propionic acid and 3,4-dihydroxyphenylalanine. FIG. 2 is a diagram showing an example of a reaction scheme for copolymerizing 3,4-dihydroxycinnamic acid and 4-hydroxyphenylalanine. FIG. 3 is a graph showing the polymerization time dependency of the molecular weight of a polymer when 3,4-dihydroxycinnamic acid and 3- (3-hydroxyphenyl) propionic acid are polymerized. FIG. 4 is a phase diagram showing that an adhesive produced using the monomer for an adhesive raw material according to this embodiment behaves as an adhesive or an adhesive depending on the molecular weight. FIG. 5 is a diagram showing the molecular weight dependence of the shear strength of an adhesive produced using the monomer for an adhesive raw material according to this embodiment. FIG. 6 is a diagram showing the change over time in the adhesiveness of the adhesive and the adhesive. FIG. 7 is a diagram showing an example of a reaction scheme of a polymer obtained by reacting a long-chain alkyl group with an acetyl residue of a copolymer polymer. FIG. 8 is a diagram showing the results of simultaneously measuring the elasticity (G ′) and viscosity (G ″) of the adhesive while changing the frequency.

  An embodiment of the present invention (hereinafter referred to as this embodiment) will be described below.

  Adhesive according to the present embodiment (in this case, an adhesive in a broad sense including both adhesive and pressure-sensitive adhesive) The raw material monomer is selected from the group consisting of the following formulas (1) to (3). Any one or two or more monomers selected from the group consisting of the following formulas (4) to (6) are used as a polymerization raw material.

The monomer of Formula (1)-Formula (3) has a catechol group (o-dihydroxyphenyl group) which is an adhesive functional group.
The monomer represented by the formula (1) is 3,4-dihydroxyhydrocinnamic acid (abbreviation DHCHA). DHHCA can be extracted from cinnamon. In this embodiment, DHHCA as a raw material monomer can be obtained as a commercially available reagent.
The monomer represented by the formula (2) is 3,4-dihydroxycinnamic acid (abbreviation DHCA). DHCA can be extracted from coffee beans. In this embodiment, DHCA as a raw material monomer can be obtained as a commercially available reagent.
The monomer represented by the formula (3) is 3- (3 ′, 4′-dihydroxyphenyl) alanine (3- (3 ′, 4′-Dihydroxyphenyl) -L-alanine: abbreviated DOPA). DOPA is an adhesive amino acid contained in mussels and can be extracted. In this embodiment, DOPA as a raw material monomer can be obtained as a commercially available reagent.

The monomers of formula (4) to formula (6) have a linear chain portion, the monomer of formula (4) gives flexibility to the molecular chain, the monomer of formula (5) gives rigidity, and the formula (6 ) Monomers can be polar.
The monomer represented by the formula (4) is 3- (3-hydroxyphenyl) propionic acid (abbreviated as 3HPPA). 3HPPA is abundant in berries and can be extracted. In this embodiment, 3HPPA as a raw material monomer can be obtained as a commercially available reagent.
The monomer represented by the formula (5) is 3- (4-hydroxyphenyl) -2-propene acid (abbreviation 4HCA). 4HCA is abundant in sweet potato stems and can be extracted. In this embodiment, 3HCA as a raw material monomer can be obtained as a commercially available reagent.
The monomer represented by the formula (6) is Tyrosine (4-Hydroxyphenil alanine). Tyrosine (also called tyrosine) can be extracted from potatoes. In the present embodiment, Tyrosine as a raw material monomer can be obtained as a commercially available reagent.

  Among the monomers of formulas (1) to (6), when DOPA and Tyrosine are used, the cholerano monomer becomes a polar substance due to an amino group, and is therefore soluble in the least toxic ethanol among organic solvents. . Further, the molecular weight can be controlled by the polymerization time, and the solubility of the monomer ethanol can be controlled.

  The method for producing an adhesive using the monomer for an adhesive raw material according to this embodiment is preferably acetylated with acetic anhydride using a phosphate catalyst, preferably various apatites as a catalyst, Two groups of monomers are ester copolymerized.

Although any method can be adopted as the copolymerization method, a bulk polymerization method or a solution polymerization method is preferable, and among these, the bulk polymerization method is more preferable.
For example, in the case of a bulk polymerization method, the raw material monomer is acetylated as necessary and then esterified.
The reaction temperature is preferably 100 to 300 ° C, more preferably 150 to 200 ° C. The reaction time is preferably 3 to 30 hours, more preferably 12 to 24 hours.
An example of a reaction scheme for copolymerizing 3- (3-hydroxyphenyl) propionic acid and 3,4-dihydroxyphenylalanine is shown in FIG. 1, and a reaction for copolymerizing 3,4-dihydroxycinnamic acid and 4-hydroxyphenylalanine. Examples of schemes are illustrated in FIG.

The blending ratio of the monomer selected from the group of formulas (1) to (3) and the monomer selected from the group of formulas (4) to (6) at the time of producing the adhesive is 10:90 to 90:10.
The amount of acetic anhydride and apatite used as the esterification catalyst is preferably 0.01 to 10 parts by mass, more preferably 0.1 to 1 part by mass with respect to 100 parts by mass of the total amount of raw material monomers. The use of hydroxyapatite (Ca10 (PO4) 6 (OH) 2) as the apatite is a preferred embodiment.

In FIG. 3, 30 mol% of 3,4-dihydroxyhydrocinnamic acid, 70 mol% of 3- (3-hydroxyphenyl) propionic acid, 10 mL of acetic anhydride and 1 mol% of apatite are acetylated at 150 ° C., and unreacted acetic anhydride and by-products Acetic acid in the product was distilled off under reduced pressure, and an adhesive (hereinafter sometimes referred to as a polymer) was collected under the conditions of 190 ° C. and 50 to 100 Pa. The obtained polymer was dissolved in DMF to obtain a 1% by mass solution. The molecular weight of the polymer was measured under the conditions of 0.25 mL / min and 40 ° C. The polymerization time dependency is shown.
The molecular weight reaches 104 g / mol which is a so-called polymer region after 2 hours of polymerization, and then the molecular weight increases, but no further increase in molecular weight is observed after 6 hours.

  FIG. 4 shows the molecular weight dependence of the melting point (melting temperature) of a polymer obtained by copolymerizing 30 mol% of 3,4-dihydroxyhydrocinnamic acid and 70 mol% of 3- (3-hydroxyphenyl) propionic acid as measured by DSC. In the figure, the ● plot and the solid line connecting it indicate the relationship between the molecular weight and the melting point. In the figure, the ▪ plot and the dotted line connecting it indicate the relationship between the molecular weight and the glass transition temperature (Tg). The polymer can be used as an adhesive in a narrow sense below the melting point, and can be used as a pressure-sensitive adhesive above the melting point. Further, from the figure, it can be seen that, for example, when the usage environment is 45 ° C. or less, those having a molecular weight significantly lower than 104 g / mol can be used as an adhesive, and those having a molecular weight greatly exceeding 104 g / mol can be used as an adhesive at room temperature.

FIG. 5 shows the molecular weight dependence of the adhesive strength of the polymer. When the molecular weight is significantly below 104g / mol, the polymer becomes viscous at room temperature, and the adhesive strength becomes 1MPa or less and can be used as an adhesive. When the molecular weight exceeds 104g / mol, it becomes elastic at room temperature and the adhesive strength becomes 1MPa or higher. Can be used as an adhesive.
FIG. 6 shows an example of the results of measuring the change in adhesiveness over time for adhesives and adhesives from polymers having different molecular weights.
Poly (DHHCA-co-3HPPA) (mixing ratio 30 mol%: 70 mol%, molecular weight about 52,000) was used as the adhesive sample, and Poly (DHHCA-co-3HPPA) (blending ratio 30 mol%: 70 mol%, molecular weight of about 4800), and the change over time in the adhesive strength / adhesive strength between glass and glass was measured.
Although measured for 2 weeks, there was not much change. Since normal adhesives are bonded by the interaction between the polymer chain and the substrate (Van der Waals force), changes over time increase the opportunity for interaction between the polymer and the substrate, and the adhesive force becomes stronger. On the other hand, it is considered that the pressure-sensitive adhesive of the present embodiment originates from the interaction between the catechol group and the substrate, not the van der Waals force.

From the above knowledge, the method for producing an adhesive using the monomer for an adhesive raw material according to the present embodiment preferably has a molecular weight of 7,000, more preferably so that the molecular weight of the polymer is significantly lower than 104 g / mol. The pressure-sensitive adhesive can be obtained by polymerizing in a range of ˜8,500 g / mol. On the other hand, the molecular weight of the polymer is preferably 30,000 to 30,000, more preferably so that the molecular weight of the polymer greatly exceeds 104 g / mol. An adhesive can be obtained by polymerizing in a range of 60,000 g / mol.
An appropriate method can be adopted as a method for adjusting the molecular weight. For example, a pressure-sensitive adhesive can be obtained with a polymerization time of 1 hour or less, while an adhesive can be obtained with a polymerization time of 2 hours or more. In addition, the pressure-sensitive adhesive and the adhesive can be separately prepared by adjusting the molecular weight of the monomer obtained by changing the combination of the raw materials for the adhesive and the blending conditions instead of the polymerization time or with the polymerization time.

As described above, the monomer for an adhesive raw material according to the present embodiment is any monomer represented by formula (1) to formula (3) and any one represented by formula (4) to formula (6). It is a raw material for obtaining an adhesive by polymerizing such monomers. By adjusting the polymerization conditions of the monomer for the adhesive raw material, it is possible to make a pressure-sensitive adhesive and an adhesive (in this case, a narrowly defined adhesive that does not include a pressure-sensitive adhesive) using the same raw material monomer.
Moreover, since the monomer for adhesive raw materials which concerns on this Embodiment is a monomer which is a natural product origin component, it is preferable.
In addition, the adhesive obtained using the monomer for the adhesive raw material according to the present embodiment as a raw material contains an aromatic ring derived from a natural product in the main chain, and therefore is relatively stable chemically and physically.
In addition, in manufacture of an adhesive agent, it does not exclude using an appropriate amount of monomers other than the formula (1) to the formula (6), which are monomers for the adhesive raw material according to the present embodiment, as necessary.

In the method for producing an adhesive using the monomer for an adhesive raw material as a raw material according to this embodiment, it is a preferred embodiment to introduce a long chain alkyl group.
As the long-chain alkyl group raw material, natural long-chain carboxylic acids such as decanoic acid, lauric acid and stearic acid can be suitably used.
An example of a reaction scheme of a polymer in which a long chain alkyl group is reacted with an acetyl residue of a copolymer polymer is shown in FIG.

  Examples of the present invention will be described below. The present invention is not limited to this embodiment.

<Manufacture of Poly (DHHCA-co-3HPPA) polymerization adhesive and adhesive>
(material)
3,4 dihydroxy hydro cinnamate Mont acid (DHHCA) (Sigma Aldrich, Product Code: STBB8922V) 3.6g and 3- (3-hydroxyphenyl) propionic acid (AK Scientific Co., Ltd., product code: MFCD00002598) 6 0.5 g of the mixture was used as a polymerization raw material.
(Adhesive production example)
Add 10 mL of acetic anhydride and 0.6 g of hydroxyapatite (product code: 59272-1606) to the above polymerization raw material, and heat for 2 hours at atmospheric pressure and 150 ° C. to acetylate DHCCA and 3HPPA. did. Subsequently, ester copolymerization was performed by heating at 190 ° C. for 6 hours under a vacuuming condition of 200 Pa or less. The molecular weight of the obtained polymer was 56, 064 g / mol.
(Adhesive production example)
DHHCA and 3HPPA were acetylated under the same conditions using the same raw materials as in the adhesive preparation example. Subsequently, ester copolymerization was performed by heating at 190 ° C. for 2 hours under a vacuuming condition of 200 Pa or less. The molecular weight of the obtained polymer was 7,372 g / mol.
(Reference production example)
DHHCA and 3HPPA were acetylated under the same conditions using the same raw materials as in the adhesive preparation example. Subsequently, ester copolymerization was performed by heating at 190 ° C. for 4 hours under a vacuuming condition of 200 Pa or less. The molecular weight of the obtained polymer was 25,476 g / mol.

<Determination of adhesive or adhesive>
A dynamic viscoelasticity measurement was carried out using a rheometer (manufactured by HAAKE, model MARSII), and used as an index for determining whether it was an adhesive or an adhesive.
For example, iron feels firm when touched slowly or quickly (ideal elastic body). On the other hand, water and honey feel soft when touched slowly (stimulating slowly), and feel firm when touched quickly (viscoelastic body). Also, liquid helium and liquid nitrogen feel smooth even when touched quickly (ideal viscous material). While changing the touching speed gradually, that is, changing the frequency of the sine wave applied by the rheometer, the elastic modulus and the viscosity are measured simultaneously with the delayed phase to respond.
Measurements are made by placing a sample with a thickness of about 100 μm on a 10 mm diameter plate called a parallel plate that maintains the temperature at 25 ° C., applying a stress of about 10 to 100 MPa, and changing the frequency to change the elasticity (G ′) and viscosity. (G ") was measured at the same time.

The measurement results are shown in FIG. In FIG. 8, Fc represents a frequency (Cross Over Frequency) at which the elasticity (G ′) and the viscosity (G ″) intersect.
In FIG. 8, (1) a polymer having a molecular weight of 7,372 g / mol shows a value lower than the viscosity term G ″ in a wide frequency range (a wide range assumed as a touching speed) to which the elastic term G ′ is added. It can be seen that this polymer is sticky.Note that G ′ and G ″ intersect at a frequency of 20 Hz corresponding to the case where the touching speed is extremely increased.
In FIG. 8, (2) a polymer having a molecular weight of 25,476 g / mol has a dominant elastic term G ′ on the high frequency side, while a viscous term G ″ predominates on the low frequency side. It can be seen that depending on the speed, in other words, depending on the conditions of use, either stickiness or adhesiveness is exhibited.
In FIG. 8, (3) the polymer having a molecular weight of 56 and 064 g / mol has a value higher than the viscosity term G ″ in all the regions of the frequency added by the elastic term G ′, and this polymer has adhesiveness. In addition, Fc is not seen.

Claims (2)

The polymerization raw material which mix | blended the monomer which consists of following formula (1), and the monomer which consists of following formula (4) with the compounding ratio of 10: 90-90: 10 changes the heating time at the temperature of 100-300 degreeC, and is ester. By the copolymerization, an adhesive having a molecular weight of 7,000 to 8,500 g / mol and an adhesive having a molecular weight of 30,000 to 60,000 g / mol are separately formed. Agent and method for producing adhesive .

The pressure-sensitive adhesive and adhesive manufacturing method according to claim 1, wherein acetic anhydride and apatite are used as a catalyst for the ester copolymerization reaction.

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