JPS6390511A - Modified polypropylene - Google Patents

Abstract

PURPOSE:To obtain the titled modified polymer having improved adhesivity, by modifying a polypropylene with an unsaturated carboxylic acid, dissolving the modified polymer in a solvent and precipitating the modified polypropylene from the solution by the addition of a poor solvent, thereby removing a low- molecular weight polymer having an intrinsic viscosity of a specific range. CONSTITUTION:A modified polypropylene is produced by melting and kneading a polypropylene and an unsaturated carboxylic acid or its anhydride (e.g. maleic anhydride) in the presence of a radical generator [e.g. 2,5-dimethyl-2,5-di(t- butylperoxy)hexyne-3]. The modified polypropylene is dissolved in a solvent of polypropylene and added with a poor solvent of polypropylene to precipitate the modified polypropylene or the modified polypropylene is extracted with a solvent such as aliphatic, alicyclic, ester or ether solvent to remove 0.5-10wt% low-molecular weight polymer having an intrinsic viscosity [eta]of 0.1-1.0.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a novel modified polypropylene. Sara K
IF+ specifically relates to a modified polypropylene with improved adhesive strength due to the removal of low molecular weight substances as described below from the modified polypropylene produced during modification, and a method for producing the same.

[Conventional technology]

In order to improve the low adhesive strength of polypropylene modified with anhydrous unsaturated carboxylic acid produced by a melting method, research has been conducted into techniques for removing unreacted monomers in the modified polypropylene, which are thought to be the cause. For example,
No. 6-9925 discloses a technique in which a polyhydric amine or a polyhydric alcohol is reacted with unreacted hexamer to make it self-sufficient in the system. Furthermore, JP-A No. 54-99195 discloses a method of extracting manufactured pellets with a solvent, and JP-A No. 56-118411 discloses a method of extracting manufactured pellets by heating.
Techniques for treating with fi-air or warm/hot water have been disclosed.

[Problems to be solved by the present invention]

However, all of the above-mentioned prior art techniques focus on removing unreacted monomers, and although unreacted monomers are removed from the modified polypropylene obtained by implementing these techniques, further improvement in adhesive strength is desired. Ta. For example, JP-A No. 54-99193 discloses that as a condition for removing adhesion inhibiting substances from modified polyolefin, it is necessary to use a good solvent for polyolefin and unreacted monomers and to treat the modified polyolefin in a temperature range in which the modified polyolefin is not substantially dissolved. In the examples, 1) modified polypropylene pellets or powder were treated with xylene or toluene) (Examples 1 to 5), or 2) A method in which acetone etc. was further added after treatment with xylene (Examples 6 to 8). .12-13)
, ■ Method of treatment with a mixed solvent such as xylene and acetone (
Examples 9-11) are shown. In such a method, all of the substances that are removed from the modified polypropylene are the adhesion inhibitors described in the same publication, and even if there are other substances that are removed depending on the conditions, they are mainly relatively crystalline substances. It is a low molecular weight substance with high properties. However, according to the research conducted by the present inventors, it has been found that the conductivity inhibiting substances that should be extracted to improve the adhesion of melt-processed carboxylic acid-modified polypropylene are low molecular weight substances of acid-modified polypropylene. . Furthermore, it is known that low molecular weight carboxylic acid without grafting has almost no effect on the adhesive strength of acid-modified polypropylene, and low molecular weight materials with low crystallinity have a negative effect on the adhesive strength of polypropylene. It has been found that these adhesion-inhibiting low molecular weight substances are effectively removed from modified polypropylene.

[Means for solving problems]

Therefore, an object of the present invention is to provide a melt-processable polypropylene with improved adhesive strength.

That is, the present invention provides a modified polypropylene obtained by melt-kneading polypropylene and an unsaturated carboxylic acid or its acid anhydride in the presence of a radical generator. By adding a poor solvent for nuclear polypropylene to precipitate modified polypropylene, or (ii) Extracting the modified polypropylene with a solvent selected from aliphatic, alicyclic, ester, and ether. The gist is a modified polypropylene obtained by removing a low molecular weight polymer having an intrinsic viscosity in the range of 0.1 to 0.

Since the modified polypropylene of the present invention is characterized as described above, the adhesive strength of the melt-process modified polypropylene, which conventionally had insufficient adhesive strength, has been improved, and the adhesive strength of nylon, saponified ethylene-vinyl acetate copolymer (hereinafter abbreviated as KVAL) has been improved. ) or the adhesion to metal gins became good. Thereby, the modified polypropylene obtained according to the invention can be made from polypropylene and other resins (e.g. nylon, EVAL).
etc.) or when forming a laminate with metal.

The polypropylene used in the present invention is a polymer containing propylene as the main monomer, such as homopolypropylene, propylene-ethylene di-andum copolymer, propylene-ethylene block copolymer, propylene-α-olefin, etc. Examples include copolymers and mixtures thereof.

Unsaturated carboxylic acids and their acid anhydrides used in the practice of the present invention include acrylic acid, methacrylic acid, maleic acid, tetrahydrophthalic acid, citraconic acid, crotonic acid, nadic acid (endocys-bicyclo(2,2 ,1
3hezoto-5-2S-2,3 dicarboxylic acid, fumaric acid,
Examples include itaconic acid or citraconic acid, maleic anhydride or itaconic anhydride, and nadic anhydride, with maleic anhydride being preferred. The amount of unsaturated carboxylic acid or its acid anhydride added is usually 0.01 to 20 P.
hr is preferably α1-5 Phr.

As the radical generator used in carrying out the present invention, organic peroxides are usually preferably used. in particular,
Butyl peroxide, di-t-butyl peroxide, 2,5-dimethyl-2,5 (di-t-butyl peroxide,
[oxy]hexane, 2,5-dimethy/l/-2,5(di-
Examples include t-butylperoxy)hexyne-3 or dichloromethane. The amount added is usually 0.00
1 to 5 Phr, preferably 0.01 to I Phr
It is.

When using the modified polypropylene of the present invention, additives that are normally added to polymers can be used. Examples of such additives include heat resistant agents, weather resistant agents, stabilizers, lubricants, antistatic agents, nucleating agents, pigments, antiblocking agents, and dyes.

The addition may be carried out by melt-kneading the above-mentioned substance together with polypropylene, an unsaturated carboxylic acid or its acid anhydride, and a radical generator using an extruder, kneader, etc. However, it is possible to add the substance after producing the modified polypropylene of the present invention. It's good to do that.

In order to remove low molecular weight substances when obtaining the modified polypropylene of the present invention, the following solvent and operation are used. That is, by dissolving the mesocorrosive polyzolopylene in a solvent (a) for polypropylene under heating, and then cooling it usually, adding a poor solvent (b) for modified polypropylene, such as an aliphatic alcohol or ketone, to precipitate it. The method is to collect modified polypropylene that is oxidized, or to extract the egg nucleus modified polyolefin using a solvent selected from aliphatic, alicyclic, ester, and ether solvents. Of the two methods, the latter is preferred from the viewpoint of operational simplicity and economy. Further, the solvent (a) in the middle method must be capable of dissolving polypropylene under heating, but the solvent (c) in the method (ii) does not necessarily have to be a polypropylene solvent. The intrinsic viscosity (5) of the low molecular weight substance to be removed is as described below, but its adjustment depends on the milk of the solution, the cooling temperature, the addition ratio of the solvent to the solvent, etc. This can be done by changing the extraction temperature, extraction time, etc.

There is generally a close relationship between the amount of low molecular weight substances removed by these operations and its intrinsic viscosity ω], and (5) generally increases as the number of children increases. However, this varies depending on the properties of the raw material modified propylene and is not always constant. The intrinsic viscosity (5) of the low molecular weight substance is α1 to t OdVg
s is preferably in the range of 0.1 to 0.9 dl/g s, particularly preferably 0.2 to 0, s ayg. The limiting viscosity (5) of the low molecular weight substance is 0.1 dL/g
If the amount is less than that, the removal of the adhesion-inhibiting low molecular weight substance described above will not be sufficient and effective. In addition, when trying to remove those whose intrinsic viscosity (5) exceeds tOc11%g,
Not only is the yield of the modified polypropylene significantly reduced, but there is no further improvement in adhesive properties.
When the intrinsic viscosity of the low molecular weight substance that cannot be used is within the above-mentioned essential range, the amount to be removed varies depending on the properties of the above-mentioned modified polypropylene, but is usually about 0. 5 or 10! It needs to be in terms of quantity, preferably α6 to 83! :1
%.

Furthermore, the crystallinity of the low molecular weight substance as determined by X-ray diffraction is usually 2.
It is 0% or less, preferably 10% or less.

ζThe solvent used here is polypropylene 80
℃ to 150℃ with a heating element, such as aromatic seismic hydrogen such as toluene and xylene, or halogenated products thereof, as well as hexane, heptane,
Examples include saturated aliphatic hydrocarbons such as decane and their nologonated versions, alicyclic hydrocarbons such as cyclohexane, and their halides. 1
Exemplary alcohols include ketones such as acetone, methyl ethyl ketone, and methyl isobutyl ketone, and lower alcohols such as ethanol, methanol, and propatool. Examples of (c) include saturated aliphatic hydrocarbons such as hexane, heptane, and decane, alicyclic hydrocarbons such as cyclohexane, esters such as amyl acetate, and ethers such as diethyl ether, preferably saturated aliphatic hydrocarbons. An example is hydrogen. Polar viscosity ω of the modified polypropylene of the present invention obtained as above]
is preferably in the range of 1.1 to 4.0 from the viewpoint of the use of the modified polypropylene as an adhesive, and particularly preferably in the range of 12 to &8.

Hereinafter, the modified polypropylene of the present invention will be described in detail according to Examples, but the invention is not limited thereto.

〔Example〕

Examples 1 to 3, Comparative Examples 1 to 3 1) To 100 parts by weight of a propylene-ethylene random copolymer with an ethylene content of 5.3 mo/I/%, 3 parts by weight of maleic anhydride and α05 parts by weight of 2,5-dimethyl-2,5-di(t-butylperoxy)hexyne-3 was mixed and extruded at 200°C using an extruder with a diameter of 15 mm and a size of 28 mm, and after cooling with water, it was solidified. It became. The modified polypropylene thus obtained was grafted with α17% by weight of maleic anhydride.

11) After crushing the modified polypropylene obtained above,
Soxhlet extraction was performed using a hexane solvent for different times to obtain a modified polypropylene extraction residue.

In Example 1, ■ of the modified polypropylene remaining after extraction was
L 40 dl/gl/side 5 had t 45417g. A strawberry sample was prepared from the modified polypropylene remaining after the extraction by the method described below, and the adhesive strength was measured.

In addition, the intrinsic viscosity ω] and crystallinity of the low molecular weight polypropylene obtained from the extraction solvent Evabore K were measured. The results are shown in Table IK. Note that an unextracted example was designated as Comparative Example 1.

Sample preparation■Press conditions: 3 minutes of preheating, 3 minutes of pressure heating (60"j'/
1m2) Temperature 230℃ ■Modified polypropylene sheet J! ! X: α11■ Test piece: Obtained by cutting Sores sheet into 11@.

■Adhesion method: Heat seal method, pressure 1ky/ca2 temperature 1
2601:, 0 aircraft landed for 5 seconds: Nylon (sheet thickness α1) 0 aircraft ai:
Instron testing machine ■Tensile speed: 50 mi/minTable 1 Comparative example 10 0 0
0 Comparative example 20.05 0.2 0
50 Comparative Example 30.08 0.4
0 80 Example 1 α13 0.7
0 200 Example 2 α17
1.0 0 440 Example 30.21
t4 0 1200 Example 4
α32 2.4 0 2400
Example 5 α40 A8 0
Non-peelable practical side 6-9 Modified polypropylene 251 obtained by repeating 1) of Example 1 was dissolved in 500-g of toluene at 100°C. This solution was left to cool to precipitate modified polypropylene, and then acetone was added and filtered to obtain a modified polypropylene sample. - On the other hand, the (2) and crystallinity of the low molecular weight substance extracted with the solvent were measured. Table 2 shows the relationship between adhesive strength and (5).

Table 2 Example 6 ioo (N8 13 0
430 Example 7 too α22 16
0 1100 Example 8 α50 0.3
2 2゜8 0 2400 Example 9 α2
5 0.63 6.5 0 Unremovable 5
A Examples 10 to 16, Comparative Example 4 100 grams of hexane was added to pellets 101 of modified polyzolopyrene obtained by repeating the steps in Example 1 for a predetermined period of time under reflux. - The adhesive strength of the pellets obtained by stirring and then filtration was measured. In addition, the intrinsic viscosity (2) and crystallinity of the obtained low molecular weight polypropylene were measured using the evaporated extraction solvent. The results are shown in Table 3.

Table 3 Comparative Example 4 0.1 α08 α5 0
75 Example 10 0.5 0.12 0.7
0 250 example 1110 α23
1.7 0 1050 Example 122.
0 0.35 3.2 0 242
0 Example 13 5.0 0.46 4.5
0 Non-peelable comparative example 5.6 Xylene 100- was added to the modified polypropylene pellets 102 obtained by repeating the steps in Example 1:) at 80°C.
The pellets were stirred for a certain period of time and then filtered, and the adhesive strength of the pellets obtained was measured.

In addition, the intrinsic viscosity (■) and crystallinity of the low molecular weight polypropylene obtained by evaporating the extraction solvent were measured. The results are shown in Table 4.

Table 4 Comparative example 5 1 105 7 31
100 Comparative Example 6 2 120 12
33 52, Patent applicant: 1 person other than Mitsui Petrochemical Industries, Ltd.

Claims (1)

[Scope of Claims] 1) From a modified polypropylene obtained by melt-kneading polypropylene and an unsaturated carboxylic acid or its acid anhydride in the presence of a radical generator, (i) using the modified polypropylene as a solvent for polypropylene; By dissolving the modified polypropylene and then adding a poor solvent for the modified polypropylene to precipitate the modified polypropylene, or (ii) dissolving the modified polypropylene into aliphatic, alicyclic,
Obtained by removing 0.5 to 10% by weight of low molecular weight polymers having an intrinsic viscosity [η] of 0.1 to 1.0 by extraction with a solvent selected from ester and ether solvents. Modified polypropylene.