JPH09278805A - Vapor deposition polymerization process - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a process for the vapor deposition polymerization capable of forming a polymer membrane even from a combination of starting monomers having a low reactivity. SOLUTION: Two or more starting monomer solutions 51 and 52 are vaporized in vacuum to form a polymer membrane 6 on the surface of a substrate 9 by polymerization. When the energy of the starting monomers adhering to the substrate is lowered before they meet each other by the migration and the total energy is lower than the activation energy necessary for the polymerization in the solution, an energy is supplied to the starting monomers on the substrate 9. The energy can be supplied by heating the substrate. A high- molecular aromatic polyurethane membrane and, a high-molecular aromatic polyester membrane which could not be obtained in the prior art are thus obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a technique for forming a polymer film, and more particularly to a technique for forming a polymer film, which has hitherto been difficult to form, by a vapor deposition polymerization method.

[0002]

2. Description of the Related Art The vapor deposition polymerization method is a technique in which a raw material monomer is evaporated in a vacuum chamber and a polymer film is formed by a polymerization reaction of the raw material monomer deposited on a substrate, which can be formed by the conventional vapor deposition polymerization method. As such polymer films, thin films of polyamic acid (polyimide precursor), polyamide, polyamideimide, polyurea, polyazomethine, etc. have been known to date.

Two kinds of raw material monomers are used in the vapor deposition polymerization method, one raw material monomer having a diamine as a functional group is used, and the other raw material monomer is acid dianhydride or acid dichloride. In many cases, monomers such as diisocyanate and dialdehyde are used. It is generally said that the combination of these raw material monomers has high reactivity, and in the solution, the polymerization reaction can proceed without the addition of a catalyst or heat treatment to form a polymer. Is.

On the other hand, from the report of observation of the behavior of organic molecules on the substrate, it is considered that the raw material monomer adhered to the substrate by the vapor deposition method also migrates on the surface of the substrate, and the behavior of the raw material monomer on the substrate is a solution. If the behavior is similar to that in, the polymerization reaction in the vapor deposition polymerization method is not the reaction in the solution, but the polymerization reaction on the surface of the substrate is the same as the polymerization reaction in the solution. The mechanism that functional groups of the monomers come close to each other has been advocated.

If the behavior of the raw material monomers on the substrate is similar to that in the solution, and if such a reaction mechanism is correct, the combination of the raw material monomers having originally low reactivity is
Depending on the vapor deposition polymerization method, the polymer film cannot be formed. This means that a polymer film of aromatic polyester and aromatic polyurethane has not been obtained, and even if these raw material monomers are co-deposited, the film obtained on the substrate is simply a mixture of the raw material monomers, It is considered to be supported by the fact that the raw material monomers for those polymer films have low reactivity.

[0006]

DISCLOSURE OF THE INVENTION The present invention is a vapor deposition polymerization technique that overturns the conventional wisdom of the prior art, and its purpose is to form a polymer film by vapor deposition polymerization even if a combination of raw material monomers having low reactivity is used. It is to provide the technology that can.

[0007]

In order to solve the above-mentioned problems, the invention according to claim 1 evaporates two or more kinds of raw material monomers in a vacuum and forms a polymer film on the surface of a substrate by a polymerization reaction. In the vapor deposition polymerization method, the value of the total energy of the raw material monomers when the raw material monomers adhere to the substrate and meet by migration on the substrate is such that the raw material monomers undergo a polymerization reaction in a solution. When the value of the activation energy at that time is less than the value, the energy is supplied to each of the raw material monomers adhered on the substrate so that the value of the activation energy is exceeded.

In this case, as in the invention described in claim 2,
The polymerization reaction occurring on the substrate is 42 kJ / in solution.
This is particularly effective in the case of a reaction that requires an activation energy exceeding mol, and replenishment of the energy can be performed by heating the substrate, as in the invention of claim 3.

According to the invention described in claim 4, it is possible to form a polymer film of polyurethane. In that case, a diol and a diisocyanate can be used as the raw material monomer as in the fifth aspect of the invention.
As the diisocyanate, a compound represented by the following formula (1) can be used.

[0010]

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On the other hand, according to the invention of claim 6, it becomes possible to form a polymer film of polyester. In that case, a diol and an acid dichloride can be used as the raw material monomer as in the invention of claim 7.
As the acid dichloride, a compound represented by the following formula (2) can be used.

[0012]

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By the way, it is generally considered that when the raw material monomer evaporated in the vacuum chamber adheres to the substrate, the raw material monomer migrates on the substrate and reacts by approaching other raw material monomers to be polymerized. In that respect, the behavior of the raw material monomer on the substrate is similar to that in the solution.

However, the energy that the raw material monomer has when reaching the substrate is only the heat of vaporization given when the raw material monomer evaporates, and the state of the raw material monomer is different from that in the solution. This means that heat loss occurs in the raw material monomers, such as radiating heat or applying heat to the substrate, before the monomers meet each other by migration.

When the total value of the heats of evaporation of the raw material monomers to be polymerized is larger than the activation energy required for the polymerization reaction on the substrate and the heat loss is negligible, a polymer film may be formed. It is possible.

On the other hand, when the sum of the heats of evaporation of both raw material monomers is slightly larger than the activation energy, the energy loss of the raw material monomers when they are encountered on the substrate is caused by heat loss. The total value falls below the activation energy required for the polymerization reaction, and the polymerization reaction does not occur. Further, when the total value of the heats of evaporation is originally lower than the activation energy of the polymerization reaction, the polymerization reaction cannot occur.

If the process in which the raw material monomers on the substrate approach each other behaves similarly to that in the solution, the polymerization reaction mechanism on the substrate is similar to that in the solution, It can be expected that the value of the activation energy on the substrate will be similar to the value of the activation energy in the solution.

If so, the value of the heat of vaporization of the raw material monomer and the value of the activation energy of the polymerization reaction in the solution are good indicators of whether or not a polymer film can be formed by the vapor deposition polymerization method. Conceivable. Therefore, the heat of vaporization of various raw material monomers was compared with the activation energy required for the polymerization reaction of various polymer compounds in solution.

The evaporation rate of the raw material monomer can be determined by performing thermogravimetric analysis in vacuum (YT
akahashi, K.Matsuzaki, M.Iijima, E.Fukuda, S.Tsukahar
a, Y.Muakami and A.Maesono, JJAppl.Phys, 32, Part 2,
L875 (1993)), the heat of evaporation can be calculated from the evaporation rate. According to the principle, the heat of vaporization ΔH of various raw material monomers was calculated to be 10 kcal / mol to 30
It was in the range of kcal / mol.

On the other hand, when the activation energy required for causing the raw material monomers to undergo a polymerization reaction in a solution was examined, it was 1 kcal / mol to 25 kcal / mol.

Analysis of the results revealed that, for a polymer film that could not be synthesized by the conventional vapor deposition polymerization method, the activation energy in the solution exceeded the sum of the heats of evaporation of the raw material monomers. It turns out that it is when it is, or when it is close.

On the contrary, if energy is supplied to the raw material monomer adhered on the substrate by taking measures such as heating the substrate to a high temperature, the energy of the raw material monomer at the time of encountering due to migration causes the polymerization reaction in the solution. Since it is possible to increase the activation energy to be equal to or higher than the value of the activation energy, it is expected that in that case, a polymer film that could not be formed by the conventional vapor deposition polymerization technique can be formed.

Actually, when vapor deposition polymerization was carried out by the method, a polymer film of aromatic polyurethane and aromatic polyester, which was conventionally impossible to form, could be formed. Therefore, it was proved that the above prediction was correct. It was

[0024]

BEST MODE FOR CARRYING OUT THE INVENTION First, calculation of heat of vaporization of raw material monomers will be described. The following chemical formula,

[0025]

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[0026]

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[0027]

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[0028]

[Chemical 6]

For the raw material monomers (PMDA, MDI, CPA, TPC) indicated by, a thermogravimetric analyzer (model: TGD7000) manufactured by Vacuum Riko Co., Ltd. was used to determine the saturated vapor pressure, and the pressure was 1.0 × 1.
Thermogravimetric analysis was performed at 0 ⁻⁴ Pa and a temperature rising rate of 1 ° C./min.
The result is the saturated vapor pressure on the vertical axis and 1000 / T on the horizontal axis.
Taking (K ^-1 ), the relationship between the saturated vapor pressure and the reciprocal of temperature is shown in the graph of FIG. In addition, the following chemical formula,

[0030]

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[0031]

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[0032]

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With respect to the raw material monomers (ODA, MDA, PPDA) represented by, thermogravimetric measurement was similarly performed in vacuum. Similarly, the relationship with the reciprocal of temperature is shown in the graph of FIG.

When the heat of vaporization (vaporization enthalpy) of each raw material monomer is obtained from the slopes of the graphs of FIGS. 2 and 3, the results shown in FIG. 4 are obtained. In FIG. 4, ◯ is a measured value, and ● is an estimated value from the evaporation temperature in vacuum. The value of this heat of vaporization is the energy received when each raw material monomer is vaporized.

From FIG. 4, among the bifunctional raw material monomers, in the aliphatic system, 10 kcal / mol to 20 kca.
1 / mol (42 kJ / mol to 84 kJ / mol), about 10 kcal / mol to 30 kcal in an aromatic system
It can be seen that it has a heat of vaporization of about / mol (42 kJ / mol to 126 kJ / mol).

Next, in the solution near room temperature, the following
The activation energy of the polymerization reaction represented by the formulas (11) to (16) was determined.

[0037]

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[0038]

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[0039]

[Chemical 12]

[0040]

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[0041]

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[0042]

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The polymer compounds synthesized by the above formulas (11) to (16) are polyamide,
Polyurethane, Polyeste
r), Polyurea, Polyamide,
It is a polyamic acid (polyamide precursor). Activation energy of each polymer compound (Activation en
energy) is shown in FIG. In FIG. 5, the polymers marked with a circle can measure the heat of vaporization of the raw material monomers, and the obtained thin film of the polymer compound can be formed by the conventional vapor deposition polymerization method.

Regarding the polymer compound plotted with (○), there is no report that a polymer film could be formed by vapor deposition polymerization with the combination of raw material monomers represented by the formula (20).
It is considered that the polymer can be formed by the conventional vapor deposition polymerization method. Regarding the polymer compounds indicated by Δ and ●, the polymer film cannot be formed by the conventional vapor deposition polymerization method.

As can be seen from FIG. 5, the activation energy of the polymerization reaction in the solution was 10 kcal / mol (4
With a combination of raw material monomers of 2 kJ / mol) or less, a polymer film can be formed by the conventional vapor deposition polymerization method, but with a combination exceeding 10 kcal / mol, the polymer film can be formed by the conventional vapor deposition polymerization method. Not formed. This time, using the vapor deposition polymerization apparatus indicated by reference numeral 2 in FIG. 1, the combination of raw material monomers in the plot of Δ in FIG.
A polymer film of polyurethane and polyester could be formed for the first time with ((12) and (13) formulas).

The vapor deposition polymerization apparatus 2 will be described together with the procedure for forming a polymer film. The vapor deposition polymerization device 2 is a vacuum chamber 3
The has an exhaust port 10 and the evaporator vessel 4 _1, 4 ₂ are found provided on the vacuum vessel 3. A vacuum pump (not shown) is connected to the exhaust port 10 so that the inside of the vacuum chamber 3 can be vacuum-exhausted, and the evaporation containers 4 ₁ , 4 ₂ can contain the raw material monomers 5 ₁ , 5 _2. Is configured.

Inside the vacuum chamber 3, a slide glass substrate having an aluminum thin film formed on the surface by vacuum vapor deposition is arranged as a substrate 9 to be film-formed, and the vacuum pump is started to activate the inside of the vacuum chamber 3. After the gas is exhausted and the substrate 9 is placed in a high vacuum atmosphere, the evaporation containers 4 ₁ , 4 ₂ are heated to generate vapors of the raw material monomers 5 ₁ , 5 ₂ . At this time,
In order for the pressure in the vacuum chamber 3 to stabilize at about 0.5 Pa,
Leave the vacuum pump running.

A heater (not shown) is provided around the vacuum chamber 3 so that the entire vacuum chamber 9 is uniformly heated and the substrate 9 is uniformly heated by the radiant heat from the vacuum chamber 9. ing. Therefore, when the vapor of the raw material monomers 5 ₁ and 5 ₂ diffuses into the vacuum chamber 3 and adheres to the surface of the substrate 9, heat energy is supplied to the raw material monomer migrating on the substrate 9. On the other hand, raw material monomer 5
Of the vapors ₁ , 5 ₂ that have been discharged from the exhaust port 10 are captured by the monomer trap 11.

Using this vapor deposition polymerization apparatus 2, the raw material monomers of the above combination were evaporated while heating the substrate 9 to form a polyurethane film and a polyester film. Even with the combination of the raw material monomers shown in Table 1 below, a polymer film of aromatic polyurethane and a polymer film of polyester could be formed on the surface of the substrate 9 under the film forming conditions.

[0050]

[Table 1]

The polymerization reaction of the polyurethane polymer film is represented by the following formula (21), and the polymerization reaction of the polyester polymer film is represented by (2)
It is shown in the equation (2).

[0052]

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[0053]

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FT-IR spectrum of the obtained polymer film was measured by a reflection method using a microscopic infrared spectrophotometer. FIG. 6 shows the measurement results of the polymer film of aromatic polyurethane. In FIG. 6, absorption at 3300 cm ⁻¹ is caused by N—H stretching vibration (stretch) of urethane bond. Also, the absorption at 1700 cm ^-1 is C of urethane bond.
= The O stretching vibration, the absorption of 1150 cm ^-1 is attributed respectively to C-O-C stretching vibration of a urethane bond. It was confirmed that polyurethane was synthesized by these absorptions.

FIG. 7 shows the FT-IR spectrum measurement result of the aromatic ester polymer film. In FIG. 7, the absorption at 1730 cm ⁻¹ is the C═O of the ester bond.
Due to stretching vibration, absorption at 1050-1275 cm ⁻¹ is due to ester-bonding C—O—C stretching vibration. By these absorptions, the synthesis of polyester was also confirmed.

Even if the same raw material monomer is co-deposited by the usual vapor deposition polymerization method, the polymerization reaction does not occur on the substrate. Even if the FT-IR spectrum of the substrate surface in that case is measured, the above-mentioned respective absorptions are It is confirmed because it cannot be observed.

In this example, as shown in Table 1, the substrate 9 was heated to replenish the raw material monomers on its surface with energy, so that aromatic polyurethane and aromatic polyester could be synthesized for the first time. .

The total value of the heats of evaporation of the raw material monomers for all polymer films is the above value in solution.
Although it is slightly larger than the activation energy of the polymerization reaction of the formulas (21) and (22), a polymer film cannot be obtained by the vapor deposition polymerization method of the prior art. Since the polymer film could be formed by applying heat energy to the raw material monomers on the base 9 this time, the cause is that when the raw material monomers meet each other due to heat loss during migration on the surface of the base 9. It was proved that it is because the energy of the energy is below the value of the activation energy.

The activation energy of the polymerization reaction in the solution of the raw material monomers described above is 10 kcal / mol.
~ 20 kcal / mol (42 kJ / mol ~ 84 kJ
/ Mol), it is possible to form a polymer film by the vapor deposition polymerization method of the present invention, even if other raw material monomers are combined, as long as the polymerization reaction falls within that range. Further, a polymer film other than the polymer film of polyurethane or polyester can be formed.

However, the activation energy of the polymerization reaction is 20
When kcal / mol (84 kJ / mol) or more,
It is necessary to keep the substrate temperature above the temperatures listed in Table 1. In that case, the raw material monomer deposited on the high temperature substrate has a shorter residence time than the case where it is deposited on the low temperature substrate, and therefore the polymer film formation rate is expected to be slow.

[0061]

[Effects of the Invention] Even when the raw material monomer attached to the substrate loses heat and the energy when it encounters due to migration falls below the value of the activation energy required for the polymerization reaction, Since energy is replenished to each raw material monomer adhered on the upper surface, it is possible to form a film of a polymer compound.

It was found that the activation energy of the polymerization reaction on the substrate was the same as the activation energy of the polymerization reaction in the solution, and it became possible to supply an appropriate amount of energy to the raw material monomers on the substrate surface. Therefore, the types of polymer membranes that can be applied are wide.

In particular, when the activation energy in the solution exceeds or is close to the total value of the heats of evaporation of the raw material monomers, conventionally, the polymerization reaction does not occur on the substrate and it cannot be formed. It has become possible to obtain the so-called polymer film. Such polymer films include a polymer film of aromatic polyurethane and a polymer film of aromatic polyester, which can be formed for the first time by the present invention.

[Brief description of drawings]

FIG. 1 is a diagram showing an example of a vapor deposition apparatus that can be used in the present invention.

[Fig. 2] Graph for obtaining heat of evaporation of raw material monomers (PMDA, MDI, CPA, TPC)

[Fig. 3] Graph for obtaining heat of vaporization of raw material monomers (ODA, MDA, PPDA)

FIG. 4 is a diagram showing heat of vaporization of each raw material monomer.

FIG. 5: Activation energy of each polymer compound

FIG. 6 FT-IR spectrum of aromatic polyurethane polymer film formed by vapor deposition polymerization

FIG. 7: FT-IR spectrum of aromatic ester polymer film formed by vapor deposition polymerization

[Explanation of symbols]

5 ₁ , 5 ₂ …… Raw material monomer 6 …… Polymer film 9 ・ ・ ・
... Base

Claims (7)

[Claims] 1. A vapor deposition polymerization method of evaporating two or more kinds of raw material monomers in a vacuum to form a polymer film on a surface of a substrate by a polymerization reaction, wherein each of the raw material monomers adheres to the substrate, When the value obtained by summing the energies of the raw material monomers when they are encountered by the above migration is lower than the activation energy value when the respective raw material monomers undergo a polymerization reaction in a solution, each of the above-mentioned each adhered on the substrate A vapor deposition polymerization method comprising supplying energy to a raw material monomer so that the activation energy exceeds the value. 2. The vapor deposition polymerization method according to claim 1, wherein the polymerization reaction occurring on the substrate is a reaction requiring an activation energy exceeding 42 kJ / mol in a solution. 3. The vapor deposition polymerization method according to claim 1, wherein the energy supply is performed by heating the substrate to a high temperature. 4. The vapor deposition polymerization method according to claim 1, wherein the polymer film is polyurethane. 5. The vapor deposition polymerization method according to claim 4, wherein diol and diisocyanate are used as the raw material monomers. 6. The vapor deposition polymerization method according to claim 1, wherein the polymer film is polyester. 7. The vapor deposition polymerization method according to claim 6, wherein diol and acid dichloride are used as the raw material monomers.