JPH11255827A - Polyvinyl acetal resin and laminate glass interlayer using same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide polyvinyl acetal resins with controlled molecular weight, molecular weight distribution and terminal groups and laminate glass interlayers using these resins with excellent sound insulating properties. SOLUTION: In a polyvinyl alcohol resin obtained by polymerizing a 3-20C vinyl ester monomer and saponifying the resulting vinyl ester polymer, this vinyl ester polymer is a polyvinyl acetal resin to be obtained by the radical polymerization of the vinyl ester monomer in the presence of an iodine compound. Laminate glass interlayers contain the polyvinyl acetal resin.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a polyvinyl acetal resin and an interlayer for laminated glass.

[0002]

2. Description of the Related Art Polyvinyl acetal resin is made of glass,
It has excellent adhesion to metal, high transparency, and excellent tensile strength.
It is used for binders, compatibilizers, varnishes for enameled wires, and the like.

If it is possible to control the molecular weight distribution of a polyvinyl acetal resin, the crystallinity, mechanical strength, flow characteristics, thermal stability, compatibility with other resins, plasticization efficiency,
It is possible to improve dispersion stability, adhesiveness, dynamic viscoelasticity and the like. In addition, if the terminal group can be controlled, the synthesis of a macromonomer utilizing the reactivity of the terminal, the use as a crosslinking point, and the synthesis of a block polymer become possible.

[0004] However, polyvinyl acetal resins are industrially obtained by saponification and acetalization of polyvinyl alcohol, and are particularly produced using vinyl acetate as a raw material. Polyvinyl acetate is industrially obtained by radical polymerization, but it is difficult to control the molecular weight, the molecular weight distribution, and the terminal group in a usual radical polymerization method because many side reactions occur.

Until now, attempts have been made to obtain a resin having a narrow molecular weight distribution by using preparative GPC of a polyvinyl acetal resin (Japanese Patent Application Laid-Open No. Hei 6-1994). Was difficult to implement.

Living radical polymerization is considered to obtain a polymer having a controlled molecular weight. In fact, various living radical polymerization methods for styrene and acrylate have been proposed (JP-A-7-126322, Macromol.
ecules 1995, 28, 8051-8056), however, in vinyl acetate, which is a raw material for polyvinyl acetal resin, chain transfer is likely to occur, and side reactions are likely to occur because the growing radical is unstable. I can't do that.

With respect to living radical polymerization of vinyl acetate monomers, Macromolecules 27,645-649 includes triisobutylaluminum, 2,2'-bipyridyl and 2,2,2-bipyridyl.
6,6-tetramethyl-1-piperidinyloxy (TEM
There is a description that living radical polymerization is possible with a catalyst system composed of three components (PO). However, it is necessary to use a metal complex unstable to air and moisture as a catalyst system, and this is not a method that can be industrially adopted.

In addition, interlayer films for laminated glass, which are useful applications of polyvinyl acetal resins, are required to have sound insulation properties in addition to the original function of preventing scattering at the time of breakage.
Japanese Unexamined Patent Publication (Kokai) No. 4-254444 proposes a device exhibiting sound insulation performance by lamination, but a satisfactory device has not yet been obtained.

[0009]

The present invention solves the above-mentioned conventional problems and provides a polyvinyl acetal resin having a controlled molecular weight, molecular weight distribution and terminal groups. Further, the present invention provides an interlayer film for laminated glass having high transparency and adhesion and excellent sound insulation at room temperature using the polyvinyl acetal resin.

[0010]

Means for Solving the Problems The present inventors have obtained a polyvinyl ester polymer having a narrow molecular weight distribution by adding a specific iodine compound to an ordinary radical polymerization system, and saponifying it. Polyvinyl alcohol resin, and, furthermore, it is found that the molecular weight distribution of the polyvinyl acetal resin obtained by acetalization is narrow, and that the degree of polymerization hardly decreases even after saponification and acetalization. It was completed.

The polyvinyl acetal resin of the present invention is a polyvinyl alcohol resin obtained by saponifying a vinyl ester polymer obtained by polymerizing a vinyl ester monomer having 3 to 20 carbon atoms. The polymer is obtained by radical polymerization of a vinyl ester monomer in the presence of an iodine compound.

Hereinafter, the present invention will be described. The vinyl ester polymer used in the present invention has 3 to 20 carbon atoms.
Obtained by polymerizing a vinyl ester monomer of the formula (1). When the number of carbon atoms of the vinyl ester monomer increases, the reactivity decreases, so that the number is limited to the above range.

Examples of the vinyl ester monomer having 3 to 20 carbon atoms include vinyl acetate, vinyl formate, vinyl propionate, vinyl butyrate, vinyl n-caproate, vinyl isocaproate, vinyl octanoate, and lauric acid. Vinyl acid, vinyl palmitate, vinyl stearate, vinyl trimethyl acetate, vinyl chloroacetate, vinyl trichloroacetate, vinyl trifluoroacetate, vinyl benzoate and the like, which may be used alone,
Two or more kinds may be used in combination. Among these, vinyl acetate is particularly preferable because it is widely used industrially.

By subjecting the vinyl ester monomer to radical polymerization by adding an iodine compound, a vinyl ester polymer having a precisely controlled molecular weight distribution (weight average molecular weight / number average molecular weight) can be obtained. . The molecular weight distribution of the vinyl ester polymer is preferably from 1.05 to 1.9. Such a vinyl ester polymer having a narrow molecular weight distribution can be obtained for the first time by the present invention. If the molecular weight distribution is less than 1.05, the synthesis is practically difficult and industrial production is impractical. If the molecular weight distribution exceeds 1.9, the high functionality and high performance aimed at by the present invention are not achieved. Achieved polyvinyl acetal resin cannot be obtained. More preferably 1.05-
1.8, more preferably 1.2 to 1.6.

As the above-mentioned iodine compound, it is preferable to use a compound having at least one bond selected from a carbon-iodine bond, a hydrogen-iodine bond and a halogen-iodine bond in a molecule.

Examples of the compound having a carbon-iodine bond in the molecule include alkyl iodide, perfluoroalkyl iodide, an adduct of hydrogen iodide with an alkene, and phenyl iodide. These iodine compounds may be used alone or in combination of two or more.

Examples of the alkyl iodide include iodomethane, iodoethane, iodopropane, iodobutane, diiodomethane, 1,2-diiodoethane, iodoform, chloroiodomethane, iodoacetonitrile, iodoacetic acid and the like. Examples of the above perfluoroalkyl iodide include iodoperfluoropropane, 1-iodoperfluorohexane, 1-iodoperfluorooctane, 1,2-diiodoperfluoroethane, 1,4-diiodoperfluorobutane, 1,6-
And diiodoperfluorohexane.

Examples of the alkene used in the adduct of hydrogen iodide and the alkene include vinyl ester monomers such as vinyl acetate, various vinyl ether monomers such as isobutyl vinyl ether, and styrene monomers. Examples of the synthesis of the adduct of hydrogen iodide and an alkene include a method of mixing anhydrous hydrogen iodide with an alkene at a low temperature.

The phenyl iodide includes, for example, iodobenzene, 2-iodoethylbenzene and the like.

The iodine compound having a hydrogen-iodine bond in the molecule includes, for example, hydrogen iodide. The iodine compound having a halogen-iodine bond in the molecule includes, for example, iodine monochloride. , Iodine trichloride, iodine monobromide and the like.

Preferred examples of the above iodine compound include:
Alkyl iodides such as iodoform, diiodomethane and iodoacetonitrile; perfluoroalkyl iodides such as 1-iodoperfluorohexane, 1,4-diiodoperfluorobutane and 1,6-diiodoperfluorohexane; hydrogen iodide and Adducts with alkenes; hydrogen iodide and the like. Further, compounds having two or more iodine atoms in one molecule, for example, iodoform, diiodomethane, 1,4-diiodoperfluorobutane, 1,6-
Diiodoperfluorohexane and the like are particularly preferred in terms of controlling the molecular weight.

The amount of the iodine compound to be used can be appropriately determined according to the molecular weight of the vinyl ester polymer to be obtained. If the amount is too small, the structure of the polymer cannot be controlled and the amount is too large. And a polymer cannot be obtained.
It is preferably 0.0001 to 0.2 mol, more preferably 0.0005 to 0.1 mol. The addition method is not particularly limited, but is preferably added before the start of polymerization from the viewpoint of control of molecular weight distribution and simplicity of operation.

Examples of the method for the radical polymerization reaction include use of a usual radical polymerization initiator; use of a photopolymerization initiator and irradiation of light; irradiation of radiation, laser light, light, and the like; heating, and the like. In particular, the use of a radical polymerization initiator is industrially preferable. As the radical polymerization initiator,
There is no particular limitation as long as it generates a radical and reacts with a vinyl ester monomer or an iodine compound to initiate polymerization, and the radical is generated by the action of heat, light, radiation, an oxidation-reduction chemical reaction, or the like. Selected from the following compounds:

Specifically, azo compounds such as azobisisobutyronitrile (AIBN), azobisisobutyrate, and hyponitrite; benzoyl peroxide (BPO);
Organic peroxides such as lauroyl peroxide, dicumyl peroxide, dibenzoyl peroxide; inorganic peroxides such as potassium persulfate and ammonium persulfate; hydrogen peroxide-ferrous iron-based, BPO-dimethylaniline-based, cerium ( IV) Redox polymerization initiators such as a salt-alcohol system and the like. Among these, AIBN, BPO
Are preferred. In the case of photopolymerization, an acetophenone-based, benzoin ether-based, ketal-based, or other photopolymerization initiator may be added.

Two or more radical polymerization initiators may be used in combination as long as they do not adversely affect the polymerization reaction by interaction. Further, a combination in which the polymerization is advanced to some extent by the action of heat and then the polymerization is completed by light can be used.

The amount of the radical polymerization initiator used is not particularly limited as long as the polymerization can be initiated, but is from 0.02 to 20 mol per 1 mol of the iodine compound used, and The amount is preferably 0.00005 to 0.5 mol per 1 mol of the body. If the amount of the radical polymerization initiator is too small, the polymerization reaction is slow and the polymerization rate is low. If the amount is too large, it is difficult to control the polymerization reaction. More preferably, it is 0.1 to 10 mol per 1 mol of the iodine compound, and 0.0001 to 0.2 mol per 1 mol of the vinyl ester monomer.

The polymerization temperature depends on the type of radical polymerization and is not particularly limited, but is preferably from -30 ° C to 120 ° C, more preferably from 0 ° C to 100 ° C. The polymerization pressure is usually carried out at normal pressure, but pressure can also be applied.

As the polymerization method, conventionally known methods such as bulk polymerization, solution polymerization, suspension polymerization and emulsion polymerization are used. In particular, bulk polymerization is preferable in order to suppress the chain transfer and obtain a better controlled polymer. Further, continuous polymerization using an extruder can also be used. In addition, alcohol, toluene, benzene, and the like can be used as a solvent for solution polymerization, but benzene is used because the chain transfer constant is relatively small during polymerization of a vinyl ester monomer and the solubility of the polymer is excellent. Is preferred.

The vinyl ester monomer may be added to the polymerization solution in its entirety from the beginning or may be added sequentially as the polymerization proceeds.

The molecular weight of the vinyl ester polymer obtained by the above radical polymerization can be adjusted by the concentration of the iodine compound, and is not particularly limited. However, when converted into a vinyl ester polymer, the number average molecular weight is 500. ~
Hundreds of thousands are preferred, more preferably a number average molecular weight of
0 to 200,000. In the present invention, it is possible to easily obtain a polymer having a narrow molecular weight distribution over a wide molecular weight distribution ranging from a low molecular weight to a high molecular weight, which is difficult with the conventional technology.

In order to improve the stability of the vinyl ester polymer, iodine existing at the growing terminal of the polymer is added by adding methanol, ammoniacal methanol, lithium borohydride or the like to the polymerization system at the time of stopping the polymerization. It may be desorbed. Irradiation with ultraviolet rays in the presence of isopentane or the like may stabilize iodine at the growth terminal of the vinyl ester polymer with hydrogen.

When the above-mentioned vinyl ester-based polymer is obtained, a block copolymer can be obtained by adding a monomer other than the vinyl ester-based monomer to the polymerization system and polymerizing it. Of course, it is also possible to block a plurality of types of vinyl ester monomers, and to block the vinyl ester monomers with styrene, acrylic or methacrylate monomers, ethylene, or the like. It is also possible.

A hyperbranched polymer can also be obtained by using an iodine compound containing a plurality of iodine which can participate in the polymerization, or by adding a small amount of divinyl monomer at the latter stage of the polymerization to carry out a crosslinking reaction. .

The vinyl ester-based polymer thus obtained is saponified to obtain a polyvinyl alcohol resin.
The saponification method is not particularly limited, and a conventional method can be used. The saponification method is roughly classified into an alkali saponification method and an acid saponification method, and any method can be used.However, preferably, a vinyl ester polymer is dissolved in an alcohol such as methanol, This is an alkali saponification method in which sodium hydroxide or sodium methylate is added. In some cases, the saponification and acetalization reactions can be performed simultaneously.

The above saponification proceeds to an appropriate degree depending on the application. Usually, the saponification degree is preferably 70 or more, more preferably 80 to 100%, further preferably 88 to 100%.

The polyvinyl alcohol resin thus obtained is acetalized to obtain the polyvinyl acetal resin of the present invention. The method for acetalization is not particularly limited, and a conventional method can be used. As a method for acetalization, a method is generally used in which an aldehyde and an acid catalyst are added to an aqueous polyvinyl alcohol solution to allow the reaction to proceed. The reaction temperature is not particularly limited, but is usually about 0 to 90 ° C. After the acetalization reaction, an acetalized resin can be obtained through steps such as neutralization, washing, and drying. These steps may be performed according to a general-purpose method, or these steps may be omitted and used in the form of an aqueous solution.

Examples of the aldehyde include n-butyraldehyde, isobutyraldehyde, n-valeraldehyde, 2-ethylbutyraldehyde, n-hexylaldehyde, n-octylaldehyde, n-nonylaldehyde, n-decylaldehyde, formaldehyde, and acetaldehyde. , Benzaldehyde and the like. These may be used alone or in combination of two or more, and may be used as a mixture with other components without departing from the spirit of the present invention.

Of the above aldehydes, it is preferable to use n-butyraldehyde, isobutyraldehyde, n-hexylaldehyde, n-octylaldehyde, formaldehyde, acetaldehyde and benzaldehyde, particularly preferably n-butyraldehyde, formaldehyde, acetaldehyde and benzaldehyde. It is.

Examples of the acid catalyst include hydrochloric acid, nitric acid, sulfuric acid and the like. Of these, hydrochloric acid is preferred.

The above acetalization proceeds to the required degree of acetalization. The required degree of acetalization varies depending on the application. For example, when used together with an aqueous solution, the degree of acetalization is preferably set low, and the degree of acetalization is preferably less than 30 mol%. When water resistance is required, the degree of acetalization is 3
It is good to be 0 mol% or more. In particular, when performing acetalization with n-butyraldehyde, the acetalization degree is set to 50.
It is good to be 90 mol%.

The degree of polymerization of the polyvinyl acetal resin can be set within a range required depending on the application. For applications such as paints, primers, adhesives and dispersants,
Those having a degree of polymerization of 100 to 3500 are preferred. In addition, for applications such as a printed circuit board in which mechanical strength and heat resistance are important, for example, those having a degree of polymerization of 800 to 5000 are suitable. In any case, if the degree of polymerization is too low, the required mechanical strength will not be exhibited, and if the degree of polymerization is too high, the viscosity will increase and the workability will deteriorate. The degree of polymerization of the polyvinyl acetal resin can be adjusted by the raw material vinyl ester polymer. In the present invention, as described above, the molecular weight (distribution) of the vinyl ester polymer can be precisely controlled, and the molecular weight (distribution) is maintained even after the above-mentioned saponification and acetalization. It is possible to obtain a polyvinyl acetal resin whose degree is narrow and whose distribution is narrow.

The molecular weight distribution (weight average molecular weight / number average molecular weight) of the polyvinyl acetal resin of the present invention is 1.05 to 1.05.
3, more preferably 1.05
3.

It has been confirmed that an alkyl group, a perfluoroalkyl group, a phenyl group or the like derived from an iodine compound is used as a starting terminal of the vinyl ester polymer which is a raw material of the vinyl acetal resin, and iodine is used as a growing terminal.
Therefore, by using an iodine compound having a functional group at the time of polymerization, a functional group can be introduced to the terminal of the polymer. Furthermore, it is possible to convert to another functional group by utilizing the reactivity of this terminal functional group or iodine, and after performing these conversions, saponification and acetalization are performed to form a vinyl acetal resin. You may.

Hereinafter, the interlayer film for laminated glass will be described. The interlayer for laminated glass is composed of a composition comprising a polyvinyl acetal resin and a plasticizer. The interlayer film obtained by using the polyvinyl acetal resin having a narrow molecular weight distribution of the present invention gives excellent results with respect to transmission loss, which is an index indicating sound insulation. This is presumably because the characteristics of the viscoelastic substance derived from the precisely controlled structure of the polyvinyl acetal resin are suitable for converting vibrational energy into other energy and suppressing sound propagation.

That is, the interlayer film for laminated glass of the present invention is obtained by saponifying or acetalizing a vinyl ester polymer having a molecular weight distribution (weight average molecular weight / number average molecular weight) of 1.05 to 1.9. It is characterized by containing an acetal resin.

If the molecular weight distribution is less than 1.05, it is practically difficult to synthesize and industrial production is impractical. If it is more than 1.9, an interlayer having excellent sound insulation properties is obtained. I can't do that. Preferably 1.05-1.
8, more preferably 1.2 to 1.6.

The sound insulation of the interlayer film is shown as a transmission loss with respect to the frequency, and the transmission loss is defined by JIS as a value corresponding to the sound insulation class. In recent years, not only large buildings but also relatively small products such as home appliances have been required to have vibration damping properties. It will improve if is improved. The interlayer film of the present invention is excellent not only in sound insulation performance but also in vibration damping properties.

The method of obtaining a polyvinyl acetal resin by saponifying and acetalizing the vinyl ester polymer having a molecular weight distribution of 1.05 to 1.9 is as described above. Hereinafter, particularly preferable ones for use in interlayer films will be described.

The aldehyde preferably used for the interlayer film for laminated glass is the aldehyde having 4 to 6 carbon atoms.
N-butyraldehyde, isobutyraldehyde,
n-Hexylaldehyde and the like are preferably used. n-
Butyraldehyde is particularly preferred.

The polyvinyl acetal resin used for the interlayer film for laminated glass is preferably made of a polyvinyl alcohol having a saponification degree of 60 to 100 mol%. If the saponification degree is less than 60 mol%, the mechanical strength is weak, which is not preferable. In particular, those having a saponification degree of 80 to 100% can be suitably used. More preferably, 85 to 10
0%.

The polyvinyl acetal resin used for the interlayer film for laminated glass preferably has an acetalization degree of 40 mol% or more. More preferably, it is 50 mol% or more, and in this range, it has a high loss coefficient, that is, a sound insulation performance.

Examples of the plasticizer constituting the interlayer film for laminated glass together with the polyvinyl acetal resin include triethylene glycol di-2-ethyl butyrate, triethylene glycol di-2-ethylhexoate, dibutyl sebacate, and the like. Di-butyl carbitol adipate and the like are used. The added amount of the plasticizer is preferably 20 to 60 parts by weight based on 100 parts by weight of the polyvinyl acetal.
If the amount of the plasticizer is less than 20 parts by weight, the penetration resistance is reduced. If the amount exceeds 60 parts by weight, the plasticizer bleeds out and impairs the transparency of the laminated glass and the adhesion to the glass plate or the like. It is.

In the present invention, it is possible to use a substance usually added for adjusting the adhesiveness between the interlayer and the glass plate, a stabilizer for preventing the deterioration of polyvinyl acetal, an ultraviolet absorber and the like. These can be used as needed when mixing polyvinyl acetal and a plasticizer, or in the process of producing polyvinyl acetal.

The intermediate film containing the polyvinyl acetal resin may be used alone or as a laminate with a film having other functions. Examples of the film include a heat ray reflection functionalized film made of polyethylene terephthalate coated with fine particles of silver or the like. A preferred combination is also a laminate of a polyvinyl butyral film that is frequently used as an intermediate film and an intermediate film containing the polyvinyl acetal resin of the present invention.

Particularly preferred examples of the laminate include the following. (1) The polyvinyl acetal resin having 5 carbon atoms
And a layer B containing a layer B containing a polyvinyl acetal resin obtained by acetalizing with butyl aldehyde, and a layer A containing a layer acetalized with aldehydes of Nos. .

(2) A layer C containing the polyvinyl acetal resin obtained by acetalizing a polyvinyl alcohol resin having a saponification degree of 80 to 96 mol% with an aldehyde having 4 to 6 carbon atoms; A layer D / layer C / layer D laminate comprising a layer D containing a polyvinyl acetal resin obtained by acetalizing at least mol% of a polyvinyl alcohol resin with butyraldehyde.

The thickness of the interlayer film of the present invention is preferably determined in consideration of the penetration resistance required as a laminated glass, and is 0.2 to 1.6 mm, which is the thickness of an ordinary interlayer film for laminated glass. Is preferred.

The method for forming the intermediate film is not particularly limited.
The usual extrusion molding is preferred. In addition, a multilayer molding machine is suitable for the production of the laminate.

In order to manufacture a laminated glass by laminating the above-mentioned intermediate film between glass plates, a method used for manufacturing a general laminated glass is employed. For example, a method of sandwiching the film from both sides thereof and manufacturing a laminated glass by a hot press is used. Further, a rigid body other than glass, for example, a metal, an inorganic material, a polycarbonate resin, or the like may be laminated.

[0060]

Next, embodiments of the present invention will be described. (Examples 1 to 3) An iodine compound,
The radical polymerization initiator and n-heptane were added so that the concentration of vinyl acetate was 9 mmol / l, and the concentrations of the iodine compound and the radical polymerization initiator were as shown in Table 1. After uniformly mixing this solution, polymerization was carried out in a separable flask while maintaining the predetermined temperature shown in Table 1. After polymerization for the time shown in Table 1, the remaining monomers were removed to obtain polyvinyl acetate. After dissolving the obtained polyvinyl acetate in methanol and adding a small amount of sodium hydroxide, alkali saponification was carried out by a conventional method to obtain a polyvinyl alcohol resin. The obtained polyvinyl alcohol resin was dissolved in pure water, the reaction system was adjusted to 3 ° C., and the amount of n-butyraldehyde shown in Table 1 and a small amount of a 35% hydrochloric acid aqueous solution were added. 4
The reaction was completed at 5 ° C. for 3 hours to obtain a white powder of polyvinyl acetal. Incidentally, the above monomers, solvents, etc.,
Unless otherwise noted, the polymerization inhibitor and impurities were removed by distillation purification, and then deoxygenated before use.

[0061]

[Table 1]

(Comparative Examples 1 to 3) Commercially available polyvinyl alcohol resins "PVA-103" and "PVA-10"
8 "and" PVA-117 "(all manufactured by Kuraray Co., Ltd.) were dissolved in pure water, and the reaction system was adjusted to 3 ° C. to adjust the amount of n shown in Table 1.
-Butyraldehyde and a small amount of a 35% aqueous hydrochloric acid solution were added. The reaction was completed at 45 ° C. for 3 hours to obtain a white powder of polyvinyl acetal.

(Examples 4 and 5) Preparation of laminated glass using the polyvinyl acetal resin of Examples 2 and 3 An amount corresponding to 40 parts by weight based on 100 parts by weight of the polyvinyl acetal resin of Examples 2 and 3. (Triethylene glycol-di-2-ethyl butyrate) is added and sufficiently kneaded with a mixing roll, and a predetermined amount thereof is kept at 150 ° C. for 30 minutes by a press molding machine to obtain a thickness of 0.38 mm. Was obtained. The above intermediate film was sandwiched between two float glass pieces of 30 cm square and 3 mm thickness from both sides, placed in a rubber bag, degassed under a vacuum of 20 torr for 20 minutes, and then kept 90% while maintaining the degassed state.
It moved to the oven of ° C, and performed the vacuum press for further 30 minutes. The laminated glass body temporarily bonded is pressed at a pressure of 12 kg /
cm ^2, and to create a laminated glass was transferred to a temperature 135 ° C. in an autoclave. Both are transparent and have a haze value of 0.4
It was below.

Comparative Examples 4 and 5 A laminated glass was produced in the same manner as in Example 4 except that the polyvinyl acetal resins of Comparative Examples 2 and 3 were used.

The following measurements were performed on the polyvinyl acetate and polyvinyl acetal resins obtained in the above Examples and Comparative Examples, and the measurement results are shown in Tables 2 and 3. (1) Polymerization ratio Measured by gas chromatography using n-heptane as an internal standard. Gas chromatography: Shimadzu "GC" Column: PEG 1500

(2) Molecular weight and molecular weight distribution of polyvinyl acetate The number average molecular weight (Mn) and weight average molecular weight (Mw)
It was measured in terms of polystyrene by gel permeation chromatography (GPC). The above Mn and Mw
The molecular weight distribution (Mw / Mn) was calculated from the measured value of. GPC: "LS8000 system" manufactured by Tosoh Corporation Column: Polystyrene gel "KF-80" manufactured by Showa Denko KK
2 "" KF-803 "" KF-804 "Solvent: chloroform, flow rate: 1 ml / min For commercial polyvinyl acetal resin of Comparative Example,
The polyvinyl acetate obtained by re-acetylation by a conventional method was measured by GPC in the same manner as in (2).

(3) Molecular weight and molecular weight distribution of polyvinyl acetal resin The number average molecular weight (Mn) and weight average molecular weight (Mw) were measured by GPC as in (2). GPC: Column manufactured by Shodex, Inc. Column: Polystyrene gel “KF-80” manufactured by Showa Denko KK
M ”× 2 Solvent: tetrahydrofuran, flow rate: 1 ml / min

(4) Degree of acetalization of polyvinyl acetal resin Measured according to JIS K6728.

(5) Tensile Strength of Polyvinyl Acetal Resin Polyvinyl acetal resin was dissolved in a mixed solvent of the same amount of ethanol and toluene to prepare a 20 to 30 wt% solution, and a film having a thickness of about 0.3 mm was formed by a casting method. After drying in an oven at 60 ° C. for 3 days, the solvent was completely removed to obtain a test piece. The obtained test piece was heated at 23 ° C., 1
A tensile test was performed under the condition of 0 mm / min, and Young's modulus was determined from the initial gradient.

(6) Thermogravimetric measurement of polyvinyl acetal resin The weight reduction starting temperature of thermogravimetric measurement was determined according to JIS K7120.
TG / DTA22 manufactured by Seiko Denshi Kogyo Co., Ltd.
0 ". Inflow gas: air, 100 ml / min, heating time: 10 ° C. /
Minute

(6) Sound Insulation Performance of Laminated Glass The prepared laminated glass (2.5 cm × 30.0 cm) was vibrated by a damping tester, and the loss coefficient obtained therefrom and the resonance frequency between the sample and the glass were measured. The transmission loss coefficient was calculated from the ratio of the resonance frequencies (measured temperature: 22).
° C). Based on this result, the TL value was defined as the minimum transmission loss amount near the frequency of 2000 Hz.

[0072]

[Table 2]

[0073]

[Table 3]

From the results shown in Table 2, it is understood that the polyvinyl acetal resin of the present invention has a narrow molecular weight distribution and is excellent in tensile strength and heat resistance. From the results in Table 3, it can be seen that the interlayer film for laminated glass of the present invention has excellent sound insulation performance.

According to the present invention, there is provided a polyvinyl acetal resin having the above-mentioned structure and having a primary structure precisely controlled. That is, a polyvinyl acetal resin having a narrow molecular weight distribution, a polyvinyl acetal resin having a controlled molecular end, a block copolymer of a polyvinyl acetal resin, and the like can be obtained by an industrially simple method. In addition, the interlayer film for laminated glass of the present invention has basic performances required for laminated glass, such as transparency, weather resistance, and adhesion to glass, and is excellent in sound insulation.

Claims (5)

[Claims] 1. A polyvinyl alcohol resin obtained by saponifying a vinyl ester polymer obtained by polymerizing a vinyl ester monomer having 3 to 20 carbon atoms, wherein the vinyl ester polymer is a vinyl alcohol resin. A polyvinyl acetal resin obtained by subjecting an ester monomer to radical polymerization in the presence of an iodine compound. 2. The vinyl ester polymer has a molecular weight distribution (weight average molecular weight / number average molecular weight) of 1.05 to 1.9.
The polyvinyl acetal resin according to claim 1, wherein 3. The compound according to claim 1, wherein the iodine compound has at least one bond selected from a carbon-iodine bond, a hydrogen-iodine bond, and a halogen-iodine bond in the molecule. 3. The polyvinyl acetal resin according to 2. 4. An interlayer film for laminated glass, comprising the polyvinyl acetal resin according to claim 1. 5. A vinyl ester polymer having a molecular weight distribution (weight average molecular weight / number average molecular weight) of 1.05 to 1.9 by polymerizing a vinyl ester monomer having 3 to 20 carbon atoms. The vinyl ester polymer is saponified to form a polyvinyl alcohol resin having a saponification degree of 80 to 100 mol%, and the polyvinyl alcohol resin has 4 to 4 carbon atoms.
6. An interlayer film for laminated glass, characterized by using a polyvinyl acetal resin having an acetalization degree of 40 mol% or more obtained by acetalization with the aldehyde of 6.