JPH05156055A - Method for forming silica coating film on polyolefin surface - Google Patents

Abstract

PURPOSE:To obtain the subject silica coating film having excellent hydrophilic property and adhesion, free from release by introducing a reactive substituent group to the surface of a polyolefin to form a coating film of a silane compound and then forming a coating film thereon by using e.g. a hydrolyzate of an alkoxy silane. CONSTITUTION:The primary coating film consisting of a silane compound expressed by formula I [R<1> is 1-6C hydrocarbon, (substituted) 1-6C organic group, H, etc.; R<2> is 1-6C hydrocarbon, 1-6C acyl or H; (n) is 0 or 1] is formed on the surface of a polyolefin in a solvent or without any solvent by partially introducing a reactive functional group to the surface of the polyolefin by radiation treatment, corona discharge treatment, etc. Then the secondary coating film is formed thereon by using either one or both of a partially hydrolyzed material of an alkoxy silane expressed by formula II (R<3> is 1-6C hydrocarbon; (n) is 0 or 1] and a silica sol to provide the objective silica coating film on the polyolefin surface having excellent hydrophilic property and adhesion and free from release of the surface-coated layer.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a surface treatment method for forming a silica coating on the surface of a polyolefin in order to improve hydrophilicity and adhesion to an inorganic material.

[0002]

2. Description of the Related Art Polyolefin moldings are used in large quantities because of their characteristics such as light weight, non-water absorption, high expansion / contraction rate, heat resistance and chemical resistance. In recent years, it has been drawing attention as a cement reinforcing material by taking advantage of the above characteristics of polyolefin. However, there are drawbacks such as poor hydrophilicity and adhesiveness, and there are methods such as radiation treatment and corona discharge treatment to improve the drawbacks of these surface characteristics, but these methods have sufficient hydrophilicity and adhesiveness. Has not been obtained. Further, a method of coating the surface of a synthetic resin molded body with a silane coupling agent has been proposed (Japanese Patent Publication No. 56-28930), however, this method has poor hydrophilicity and sufficient adhesiveness cannot be obtained. As a method for coating the surface of the synthetic resin with the metal oxide, vacuum deposition, sputtering, ion plating, plasma CVD
Methods such as are known. The synthetic resin coated with silicon dioxide by these methods exhibits high hydrophilicity and excellent adhesion between the metal oxide coating and the inorganic material. However, the synthetic resin coated with silicon dioxide by these methods does not have sufficient adhesion between the resin surface and the silicon dioxide coating layer. There has been proposed a method of forming a silicon dioxide film on the surface of a synthetic resin molded article by subjecting the surface of the synthetic resin to a primer treatment with a silane coupling agent (Japanese Patent Laid-Open No. 61-12734). If used, the adhesive strength between the polyolefin and the primer is not sufficient,
Interfacial peeling occurs from there. The reason for this is that there is no reactive functional group on the surface of the polyolefin molded body, so that no strong chemical bond is formed between the polyolefin and the primer.

A method of binding silane to polyolefin by coating the surface of the polyolefin with a silane compound and then carrying out graft polymerization by electron beam irradiation is disclosed in US Pat.
No. 803126. However, since this method uses a hydrolyzate of an organic silane, it is difficult to coat the silane layer thinly and uniformly, and the utilization efficiency of the organic silane deteriorates. In addition, JP-A-2-42328
However, a method of forming a silane layer using a hydrolyzate of an organic silane has been shown, but since this method also uses a hydrolyzate of an organic silane, a thin and uniform coating of the silane layer is achieved. It is difficult to do so, and the utilization efficiency of the organic silane deteriorates.

[0004]

Among the conventional polyolefin surface treatment methods, a modification method which is excellent in hydrophilicity and adhesiveness and does not cause peeling of the surface coating layer has not been developed yet.
The present invention is intended to solve this problem.

[0005]

Means for Solving the Problems As a result of repeated research to improve the problems of the above-mentioned prior art, the present inventors have partially introduced a reactive functional group into the surface of a polyolefin and A first coating composed of a silane compound represented by the following general formula (1) is formed without a solvent, and an alkoxysilane represented by the following general formula (2) is used in an amount of 0 to 100 parts by weight of a partial hydrolyzate, silica sol 0 to 100. By the method of forming the second coating using parts by weight, it shows high hydrophilicity,
We have established a surface treatment method for polyolefins that has excellent adhesion to inorganic materials and that does not cause peeling of the surface coating layer.

General formula (1) R ¹ _n Si (OR ² ) _(4-n) n = 0 to 2 (wherein R ¹ is a hydrocarbon group having 1 to 6 carbon atoms, or an amino group, a mercapto group, Epoxy group, methacryloxy group,
1 to 1 carbon atoms including substituents such as alkoxy groups and halogens
6 is an organic group, or one or more bonding groups selected from hydrogen, R ² is a hydrocarbon group having 1 to 6 carbon atoms,
Alternatively, it is an acyl group having 1 to 6 carbon atoms or hydrogen. )

For example, methyltrimethoxysilane, methyltriethoxysilane, ethyltrimethoxysilane, ethyltriethoxysilane, dimethyldimethoxysilane,
Dimethyldiethoxysilane, phenyltrimethoxysilane, phenyltriethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, vinyltris (2
-Methoxyethoxy) silane, vinyltriacetoxysilane, allyltrimethoxysilane, allyltriethoxysilane, methylvinyldimethoxysilane, methylvinyldiethoxysilane, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, N-
(2-aminoethyl) -3-aminopropyltrimethoxysilane, N- (2-aminoethyl) -3-aminopropylmethyldimethoxysilane, 3-mercaptopropyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-methacryloxymethyldimethoxysilane,
3-chloropropyltrimethoxysilane, 3-chloropropyltriethoxysilane, 3-chloropropylmethyldimethoxysilane, 3-chloropropylmethyldiethoxysilane, tetramethoxysilane, tetraethoxysilane, trimethoxysilane, triethoxysilane, etc. can give.

General formula (2) H _n Si (OR ³ ) _(4-n) n = 0,1 (wherein R ³ is a hydrocarbon group having 1 to 6 carbon atoms)

Examples thereof include tetramethoxysilane, tetraethoxysilane, tetrapropoxysilane, tetrabutoxysilane, tetraphenoxysilane, trimethoxysilane, triethoxysilane, tripropoxysilane, tributoxysilane and triphenoxysilane.

In the present invention, since the coating film is formed without hydrolyzing the silane compound, a thin and uniform coating film can be formed even on the polyolefin surface having a small critical surface tension. The structure of the present invention is as follows.

(A) A reactive functional group is partially introduced on the surface of the polyolefin. The method of introducing the reactive functional group includes, but is not limited to, irradiation treatment and corona discharge treatment. -When the electron beam irradiation treatment is performed, it is preferable to expose to a gas containing oxygen (air or the like) after the electron beam irradiation. -Electron beam is 0.1 to 30 Mrad, preferably 1 to 1
Irradiate with 5 Mrad.

When the solvent (b-1) is used, the silane compound represented by the general formula (1) is dissolved in the following solvent to prepare a silane compound solution having a concentration of 100 to 0.01 w%. Immerse the polyolefin into which the reactive substituent has been introduced. Taking out the polyolefin from the silane compound solution, at 0 to 200 ° C, preferably 20 to 150 ° C,
The first coating is formed by drying for 0.1 to 300 minutes, preferably 1 to 100 minutes. The solvent for preparing the silane compound solution is
A solvent having a surface tension smaller than the critical surface tension of the polyolefin partially introduced with a reactive substituent is preferable.
For example, hydrocarbons (hexane, toluene, etc.), ethers (diethyl ether, dioxane, dimethoxyethane, etc.), alcohols (methanol, ethanol, etc.),
Esters (ethyl acetate, etc.) are included, but not limited thereto. The temperature of the silane compound solution may be any temperature above the melting point and below the boiling point of the solvent used, but is preferably 0 to 80 ° C. The immersion time in the silane compound solution is 0.01 second to 24 hours, preferably 0.1 second to 1 hour.

(B-2) In the case of carrying out without solvent, the polyolefin partially introduced with the reactive substituent is immersed in the silane solution represented by the general formula (), or the polyolefin represented by the general formula () is used.
Leave in silane vapor. Take out the polyolefin from the reactor, 0-200 ℃, preferably 20-150 ℃
And then dried for 0.1 to 300 minutes, preferably 1 to 100 minutes,
Form a first coating. -The temperature of the method of immersing in a silane liquid is 0 to 200 ° C, preferably 0 to 80 ° C.・ The time of the method of immersing in silane liquid is from 0.01 second to 24
The time is preferably 0.1 second to 1 hour. -The temperature of the method of leaving it in silane vapor is 0 to 200.
C, preferably 0 to 100C. -The time of the method of leaving it in silane vapor is 0.01 second to 24 hours, preferably 0.1 second to 1 hour.

(C) Alcohol 10 having 6 or less carbon atoms below
One or both of 0 parts by weight, 0 to 100 parts by weight of water, 0.01 to 100 parts by weight of alkoxysilane represented by the general formula (2) or 0.01 to 100 parts by weight of silica sol,
Add acid or alkali to adjust pH to 4-12, preferably 6
The polyolefin having the first coating formed by the above method (b-1) or (b-2) is immersed in the silica solution prepared in 10 to 10 to form the second coating of SiO ₂ . -The temperature of immersion in the silica solution is 0 to 200 ° C, preferably 0 to 120 ° C. The immersion time in the silica solution is 0.01 second to 24 hours, preferably 0.1 second to 1 hour. -Examples of alcohols having 6 or less carbon atoms include methanol, ethanol, propanol, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, and diethylene glycol monoethyl ether. The SiO ₂ thin film may be formed by any of the above-mentioned dip coating method, wet method such as precipitation method using a saturated silicon dioxide solution, vacuum deposition, sputtering, ion plating, and dry method such as plasma CVD. The wet method is preferable in order to form a uniform film on a polyolefin having an arbitrary shape. Also, when used for applications such as cement reinforcement,
In order to prevent deterioration of the inorganic material due to acid, it is preferable to form the silica thin film under neutral or alkaline conditions.

[0015]

The present invention will be described in more detail with reference to the following examples and comparative examples. In carrying out the electron beam irradiation, an area beam type electron beam irradiation device (Curetron EBC-200-AA2 manufactured by Nisshin High Voltage Co., Ltd.) was used. The critical surface tension / peeling test / pull-out strength test in Examples and Comparative Examples was performed by the following methods.

Critical surface tension : Staining reagent (Wako Pure Chemical, 3
The critical surface tension was measured using 1 to 54 dyn / cm).

Peeling test : 1 mm long and 1 m wide on the surface of the thin film formation
100 grids of m were cut and peeled off with a cellophane adhesive tape, and the number of remaining grids was evaluated. A: Remaining number 100 B: Remaining number 90 to 99 C: Remaining number 1 to 89 D: Remaining number 0

Pull-out strength test : Adhesion test pieces were prepared using a cement mortar tensile test jig according to Japan Concrete Institute Fiber Adhesion Test Method (JCI-SF8) ASTM C190,
Then, it was measured by a tensile test. That is, a polypropylene plate is cut into a length of 35 mm (width 20 mm, thickness 1 m
m), penetrating a gap of about 1 mm Teflon plate, about 10 mm on one side (pull-out side), about 2 on the other side (fixed side)
Fix it to 5 mm. 2 for one test piece
Fix in the center of the form making mold, and continue to mix ordinary Portland cement (C), Toyoura standard sand (S), and water (W) at a mixing ratio of C: S: W = 1: 1.7: 0.5. The mortar paste kneaded in was poured into a mold, demolded the next day, and cured in a moist air for 6 days. On the 7th day from the date of preparation of the test piece, a tensile test was performed at a loading speed of 0.5 mm / min, and a pull-out strength test was performed.

(Example 1) Polypropylene flat plate (PP)
(75 mm × 70 mm × 1 mm) electron beam (accelerating voltage 1
Irradiation with 50 KeV, 10 Mrad). The polypropylene flat plate after the electron beam irradiation was left in the air and then heated in a 0.5 wt% dimethoxyethane solution of 3-aminopropyltriethoxysilane (AMS) at 60 ° C. for 30 minutes. After the reaction was completed, it was dried at 100 ° C. for 1 hour to form a first coating.
The polypropylene flat plate on which the first coating film was formed was placed in a solution prepared by dissolving 10 parts by weight of tetraethoxysilane and 2 parts by weight of 0.05N sodium hydroxide aqueous solution in 100 parts by weight of ethanol, and heated at 80 ° C. for 2 hours. 100 after the reaction
It dried at 4 degreeC for 4 hours, the 2nd film was formed, and the silica coating polypropylene slab was obtained.

(Examples 2 to 7) In addition to the silane of Example 1, 3
-Methacryloxypropyltrimethoxysilane (MA
S), 3-glycidoxypropyltrimethoxysilane (EPS), allyltriethoxysilane (ATES),
Vinyltriethoxysilane (VTES), methyltriethoxysilane (MTES), tetraethoxysilane (T
The same operation as in Example 1 was carried out except that EOS) was used to obtain a silica-coated polypropylene flat plate.

(Example 8) Polypropylene flat plate (PP)
(75 mm × 70 mm × 1 mm) electron beam (accelerating voltage 1
Irradiation with 50 KeV, 10 Mrad). The polypropylene flat plate after electron beam irradiation was left in the air, then left in 3-aminopropyltriethoxysilane (AMS) at 25 ° C. for 5 minutes, taken out from the reaction solution, and dried at 100 ° C. for 1 hour to form a first coating. .. The polypropylene flat plate having the first coating formed thereon is treated in the same manner as in Example 1 to form the second coating,
A silica-coated polypropylene plate was obtained.

Example 9 Polypropylene Flat Plate (PP)
(75 mm × 70 mm × 1 mm) electron beam (accelerating voltage 1
Irradiation with 50 KeV, 10 Mrad). After leaving the polypropylene plate exposed to the electron beam in the air, at 25 ° C for 3
After leaving it in the vapor of -aminopropyltriethoxysilane (AMS) for 5 minutes, it was taken out of the reactor and dried at 100 ° C for 1 hour to form a first film. The same treatment as in Example 1 was applied to the polypropylene flat plate on which the first coating was formed to form the second coating, and a silica-coated polypropylene flat plate was obtained.

Comparative Example 1 The pull-out strength of an untreated polypropylene flat plate was measured.

Comparative Example 2 A silica-coated polypropylene flat plate was obtained by performing the same operations as in Example 1 except that the polypropylene flat plate was not subjected to electron beam irradiation treatment.

(Comparative Example 3) Polypropylene flat plate (PP)
(75 mm × 70 mm × 1 mm) was heated in a 0.5 wt% dimethoxyethane solution of 3-aminopropyltriethoxysilane (AMS) at 60 ° C. for 30 minutes. After completion of the reaction, the product was dried at 100 ° C. for 1 hour and then electron beam (acceleration voltage 150
KeV, 10 Mrad) was irradiated to form the first coating. The same treatment as in Example 1 was applied to the polypropylene flat plate on which the first coating was formed to form the second coating, and a silica-coated polypropylene flat plate was obtained.

Table 1 shows the results of the critical surface tension / peel test and pull-out strength test of Examples 1 to 9 and Comparative Examples 1 to 3.

[0027]

[Table 1]

(Example 10) Polypropylene flat plate (PP) subjected to corona discharge treatment (75 mm x 70 mm x 1 m)
m) to 3-aminopropyltriethoxysilane (AM
3) in a 0.5 wt% solution of S) in dimethoxyethane at 60 ° C.
Heated for 0 minutes. After the reaction is completed, it is dried at 100 ° C. for 1 hour,
A first coating was formed. The same treatment as in Example 1 was applied to the polypropylene flat plate on which the first coating was formed to form the second coating, and a silica-coated polypropylene flat plate was obtained.

Example 11 Polyethylene flat plate (PE)
The same operation as in Example 1 was carried out except that (75 mm × 70 mm × 1 mm) was used to obtain a silica-coated polyethylene flat plate.

(Embodiment 12) A polyethylene flat plate (PE) subjected to corona discharge treatment (75 mm × 70 mm × 1 mm)
The same operation as in Example 10 was carried out except that was used to obtain a silica-coated polyethylene flat plate.

Comparative Example 4 The pull-out strength of an untreated polyethylene flat plate was measured.

Table 2 shows the results of the critical surface tension / peel test and pull-out strength test of Examples 10 to 12 and Comparative Example 4.

[0033]

[Table 2]

(Example 13) At the time of forming the second coating, 9.5 parts by weight of tetraethoxysilane and 0.
A silica-coated polypropylene flat plate was obtained in the same manner as in Example 1, except that a solution prepared by dissolving 5 parts by weight and 2 parts by weight of 0.05N sodium hydroxide aqueous solution in 100 parts by weight of ethanol was used.

Example 14 A silica-coated polypropylene flat plate was obtained in the same manner as in Example 1 except that a solution prepared from 30 parts by weight of silica sol and 100 parts by weight of ethanol was used in forming the second coating. ..

Example 15 The same operation as in Example 1 was carried out except that a solution prepared from 30 parts by weight of silica sol, 100 parts by weight of ethanol and 5 parts by weight of tetraethoxysilane was used at the time of forming the second coating. A silica-coated polypropylene plate was obtained.

Table 3 shows the results of the critical surface tension / peel test and pull-out strength test of Examples 13 to 15.

[0038]

[Table 3]

Example 16 Polypropylene 2D tow (37000D, 50 cm) was exposed to an electron beam (accelerating voltage 15
It was irradiated with 0 keV and 10 Mrad). After leaving the electron beam-irradiated polypropylene 2D tow in the air, it was heated in a 1 wt% 1,2-dimethoxyethane solution of 3-aminopropyltriethoxysilane at 60 ° C. for 30 minutes. After completion of the reaction, the reaction solution was taken out and dried at 100 ° C. for 1 hour to form a first coating. 10 parts by weight of tetraethoxysilane, 0.1 parts of polypropylene 2D tow on which the first coating was formed,
2 parts by weight of N sodium hydroxide aqueous solution was added to 100
The solution was dissolved in 1 part by weight and heated at 80 ° C. for 2 hours. After the reaction was completed, it was dried at 100 ° C. for 4 hours to form a second coating film, and a silica-coated polypropylene 2D tow was obtained. Silica-coated polypropylene 2D tow was cut to 5 mm.
The slurry was adjusted so that the solid content concentration was 10% at the compounding ratio shown in Table 4, and the paper was cut with a wire mesh of 50 mesh and then 5
It was pressed at 0 kg / cm 2. After the press, it was naturally cured for 1 day and then autoclaved at 170 ° C. for 5 hours.
A bending strength test was performed on the prepared plate according to JIS A 1408.

(Comparative Example 5) Untreated polypropylene 2D
The tow was cut into 5 mm, the slurry was adjusted to have a solid content concentration of 10% at the compounding ratio shown in Table 4, and the mixture was made with a 50-mesh wire net and then pressed at 50 kg / cm 2.
After the press, it was naturally cured for 1 day and then autoclaved at 170 ° C. for 5 hours. Created board is JIS A 14
Bending strength test was performed according to 08.

Table 4 shows the results of the bending strength tests of Example 16 and Comparative Example 5.

[0042]

[Table 4]

[0043]

[Effects of the Invention] Even if untreated polyolefin was coated with silica, the pull-out strength was hardly improved. However, when a polyolefin having a reactive functional group partially introduced on the surface is coated with silica, the pull-out strength is 1.6 to
It was 2.3 times, and the adhesiveness with inorganic materials was improved. The effect of the silane compound containing an amino group was particularly remarkable. When polypropylene fibers coated with silica were used, the bending strength was improved, and the dispersibility of the polypropylene fibers in the slurry was improved, improving workability. According to the present invention, a silica thin film having excellent adhesion to hydrophilic and inorganic materials can be formed on the surface of polyolefin. Therefore, when a polyolefin coated with a silica film is used as a cement reinforcing material, it has an improved workability and a cement reinforcing effect.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Internal reference number FI Technical display location D06M 13/517 D21H 13/14 7199-3B D21H 5/20 B (72) Inventor Masatoshi Horiguchi Kanagawa 5-1, Okawa-cho, Kawasaki-ku, Kawasaki-shi, Chemical Research Laboratory (72) Inventor, Toyoharu Matsunaga 5-1-1, Okawa-machi, Kawasaki-ku, Kawasaki, Kanagawa Prefecture (72) Inventor Teruyuki Sato 5-1 Okawa-cho, Kawasaki-ku, Kawasaki-shi, Kanagawa Akira Denko Chemicals Research Laboratory

Claims (4)

[Claims] 1. A reactive functional group is partially introduced into the surface of (a) a polyolefin by irradiation treatment, corona discharge treatment, etc., and (b) in a solvent or without a solvent, represented by the following general formula (1): Forming a first coating comprising a silane compound shown below, and (c) forming a second coating using one or both of a partial hydrolyzate of an alkoxysilane represented by the following general formula (2) or silica sol. A method for forming a silica coating on the surface of a polyolefin. Formula _{^{(1) R 1 n Si (}} OR 2) (4-n) n = 0~2 ( wherein R ¹ is a hydrocarbon group having 1 to 6 carbon atoms or an amino group, a mercapto group, an epoxy group, Methacryloxy group,
1 to 1 carbon atoms including substituents such as alkoxy groups and halogens
6 is an organic group, or one or more bonding groups selected from hydrogen, R ² is a hydrocarbon group having 1 to 6 carbon atoms,
Alternatively, it is an acyl group having 1 to 6 carbon atoms or hydrogen. ) General formula _{(2) H n Si (OR} 3) (4-n) n = 0,1 ( wherein R ³ is a hydrocarbon group having 1 to 6 carbon atoms) 2. The method for forming a silica coating on the surface of a polyolefin according to claim 1, wherein the method (b) for forming the first coating is a method using vapor of a silane compound represented by the general formula (1). 3. The silica on the polyolefin surface according to claim 1, wherein the solvent (b) is a solvent having a surface tension smaller than the critical surface tension of the polyolefin having a surface partially introduced with a reactive functional group. Film forming method. 4. The method of introducing a reactive functional group according to (a) above,
The method for forming a silica film on a polyolefin surface according to claim 1, which is a method of exposing to a gas containing oxygen after electron beam irradiation.