JPH02194033A - Production of polyolefin molding of improved adhesiveness - Google Patents

Abstract

PURPOSE:To obtain the title molding improved in adhesiveness to a polar material by oxygenating the surface of a molding without forming any irregularities thereon by subjecting the polyolefin molding to plasma discharge treatment in a gaseous atmosphere of vaporizable organic and/or inorganic compounds. CONSTITUTION:A highly oriented polyolefin molding obtained by molding a high-MW polyolefin (e.g. PE) of an intrinsic viscosity >=3dl/g in decalin at 135 deg.C under conditions to cause a decrease in intrinsic viscosity <=14% is subjected to plasma discharge treatment in a gaseous atmosphere of vaporizable organic and/or inorganic compounds (e.g. acrylic acid, allylamine or NH3), desirably a carboxy and/or amino monomer to oxygenate the surface of the molding to a degree of at least four oxygen atoms per 100 carbon atoms.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a method for producing a polyolefin molded article with improved adhesion, and more specifically, to a method for manufacturing a polyolefin molded article with improved adhesion. Polyolefin molding that uses plasma discharge treatment in a gas atmosphere of volatile organic and/or inorganic compounds to add oxygen without creating irregularities on the surface of the molded product and improves its adhesion to polar matrix materials. Concerning the manufacturing method of the product.

(Conventional technology and its problems) Fiber-reinforced plastics have excellent strength and rigidity, so they are used in automobile parts, electrical appliance parts and housings, industrial materials,
It is used in a wide range of applications, including small ships, sporting goods, medical materials, civil engineering materials, and building materials. However, since most of the birch fiber reinforcing agents used in it are glass fibers, the resulting composite material has the disadvantage of being heavier than unreinforced plastic. In the field where composite materials with physical strength are desired, sufficient measures have not yet been taken.

On the other hand, filaments, tapes and
Stretched molded bodies such as films have the characteristics of high elasticity, high strength, and light weight, and are therefore in the spotlight as reinforcing materials for composite materials that are desired to be lightweight.

However, although polyolefin has such excellent characteristics, it has a fatal drawback of poor adhesion with other polar materials, so it is naturally limited as a matrix material as a reinforcing material for composite materials. There is a problem that

Therefore, methods have been proposed for improving adhesive properties by subjecting the surface of polyolefin to various treatments.

For example, Japanese Patent Publication No. 53-794, and Japanese Patent Publication No. 57-
Publication No. 177032 discloses a method of forming a large number of fine irregularities of about 0.1 to 4μ on the surface of a polyolefin molded product by subjecting the polyolefin molded product to plasma discharge treatment to improve the adhesiveness with the matrix material. In addition, Japanese Patent Publication No. 58-53DL4 and Japanese Patent Application Laid-Open No. 60-146078 disclose a method of treating a polyolefin molded article with a corona discharge treatment to improve its adhesion with a matrix material. There is.

However, all of these methods improve the adhesion with polar materials by forming many fine irregularities on the surface of the polyolefin molded product, which improves the adhesion to polar materials by a large amount compared to untreated products. A decrease in tensile strength, etc. is unavoidable, and this tendency occurs, for example, when the total irradiation dose is 0.05 to 3
．． Even when applying a weak corona discharge treatment of 0 watts/min/m2, very fine haze (h
6 of the untreated product because it causes
There is a problem that the tensile strength decreases to about 0 to 70%, and it cannot be used for molded products such as composite materials that require high tensile strength.

(Problems to be Solved by the Invention) As described above, in order to improve the adhesion between a polyolefin molded product, especially a highly oriented polyolefin molded product, and a polar material, fine particles are applied to the entire surface of the molded product by plasma discharge treatment or the like. It is thought that creating irregularities to increase the adhesion specific surface area with polar materials or to exhibit an anchoring effect is an essential condition, and it is believed that it is an essential condition to improve the adhesion of thin filaments such as ultra-high molecular weight polyethylene filaments. teeth,
It was believed that a slight decrease in strength was unavoidable.

However, for molded products that do not require much strength, such as films, there is no problem even if unevenness is generated on the entire surface, but for ultra-high molecular weight polyolefin filaments, which are characterized by high elastic modulus and high tensile strength, even if adhesive Even if it is an improvement, a decrease in strength etc. means a loss of its characteristics, and this is something that must be avoided at all costs.

In view of this situation, the present inventors have conducted intensive studies on a method for improving the adhesion of oriented polyolefin molded products without generating minute irregularities on the entire surface thereof. As a result, the molecular weight of the raw material for polyolefin molded products has been Molded products that are manufactured with as little deterioration as possible do not generate minute irregularities on the entire surface even when subjected to surface treatments such as plasma discharge treatment, and moreover, they do not allow the addition of more than a certain amount of oxygen to the surface. They found that the adhesive properties were significantly improved and there was almost no decrease in strength, etc., leading to the completion of the present invention.

(Means for Solving the Problems) According to the present invention, a high molecular weight polyolefin having an intrinsic viscosity [η] of 3 dJ2/g or more measured in a decalin solvent at 135°C is reduced in its intrinsic viscosity [η]p. A highly oriented polyolefin molded product obtained by molding under conditions where the ratio is 14% or less is subjected to plasma discharge treatment in a gas atmosphere of a volatile organic compound and/or inorganic compound. A method for manufacturing a polyolefin molded article with improved adhesion is provided, and according to this method, a polyolefin molded article buried in plasma has at least 4 oxygen atoms per 100 carbon atoms on its surface. This method can improve the adhesion of polyolefin molded products without creating fine irregularities on the surface of the molded product, unlike conventional plasma discharge treatment or corona discharge treatment.

(Function) The present invention provides highly oriented high molecular weight polyolefin,
A polyolefin molded article molded with the rate of decrease in its intrinsic viscosity [η]p kept at 14% or less, preferably 10% or less, and more preferably 7% or less, is molded with a vaporizable organic compound and/or
Or, by plasma discharge treatment in an inorganic compound gas atmosphere, at least 4, preferably 6 or more, more preferably 8 or more oxygen atoms are added to the surface of the molded article per 100 carbon atoms, This improves the adhesion with polar materials, and since this plasma discharge treatment can be performed while keeping the surface of the polyolefin molded product smooth, it improves adhesion without reducing the tensile strength of the molded product. This was done based on the findings of the present inventors that the properties can be improved.

(Description of preferred embodiments) The high molecular weight polyolefin used in the present invention has an intrinsic viscosity [η] measured at 135°C in a decalin solvent.

is 3dA/g or more, preferably 5dJL/g or more,
More preferably, it is from 7 to 3 di/g, particularly from 1 to 15 di/g. Such high molecular weight polyolefins include, for example, ethylene, propylene,
Examples include homopolymers or copolymers of 1-butene, 1-pentene, 1-hexene, 1-octene, 1-decene, and 4-methyl-1-pentene; among these, ethylene homopolymers or ethylene A highly crystalline copolymer of acetic acid and a small amount of other α-olefin is preferred because it can achieve higher modulus of elasticity and higher tensile strength and is particularly suitable as a reinforcing material.

In the present invention, the term "smooth surface of a polyolefin molded product" means that the surface of a polyolefin molded product subjected to electrical discharge treatment is observed with an electron microscope using the following method, and the crack width in the orientation direction on the surface is 0.1 μm or more, preferably 0. .08μm or more unevenness is not generated. If the surface of the polyolefin molded product is not smooth, for example, 0.1
If fine irregularities of μm or more are formed over the entire surface, mechanical strength such as tensile strength is reduced.

The method for observing the surface condition of polyolefin molded products is divided into two steps: pretreatment and photography. That is, in the pretreatment, (1) A cover glass is fixed to the sample stage with double-sided tape, and a sample is fixed on top of it with double-sided tape.

(2) Conductive paint (silver paste, Sylvest P-225
) is applied between the sample stage and the sample, and between the cover glass and the sample stage.

(3) Using JEE 4B manufactured by JEOL, vacuum evaporate gold onto the sample surface. In addition, the photo was taken using JEOL JS
Performed at 3000x magnification with M25 SHI, at this time,
The acceleration voltage is 12.5KV.

Furthermore, if the amount of oxygen added to the surface of the polyolefin molded product is less than 4, the adhesion to polar materials will not be improved.

The amount of oxygen added to the surface of the polyolefin molded product was measured as follows. That is, using an X-ray photoelectron spectrometer (Shimadzu Corporation ESCA 750 model), a sample stage with a sample fixed with double-sided tape was introduced, and the degree of vacuum was increased to 10".
” After setting it to Torr, use it as a light source.
1488,6eV) is used for IteCI! and OIs were measured. After measurement, waveform processing was performed, and the area of each peak was calculated to determine the amount of oxygen relative to carbon.

The present invention provides high molecular weight polyolefins having an intrinsic viscosity [η] of 3 dfL/g or more measured in the above-mentioned decalin solvent at 135°C, with a reduction rate of the intrinsic viscosity [η]p of 14% or less, preferably 10% or less. More preferably, a highly oriented polyolefin molded article obtained by molding with a content of 7% or less is subjected to plasma discharge treatment in a gas atmosphere of a volatile organic compound and/or inorganic compound.

The rate of decrease in the intrinsic viscosity [η]p of polyolefin molded products is 1
If the content exceeds 4%, fine irregularities of 0.1 μm or more will be formed on the entire surface when subjected to discharge treatment, which will further reduce the mechanical strength.

Intrinsic viscosity [η
] The reduction rate (%) of p is a numerical value defined by the following formula.

In the formula, [η]m is the intrinsic viscosity (dfL) of the raw material polyolefin
/g), and [η]p represents the intrinsic viscosity (dIl/g) of the highly oriented polyolefin molded article.

The plasma discharge treatment of the olefin molded article can be carried out using, for example, a known discharge device such as a high frequency discharge, a microwave discharge, or a glow discharge.

Compounds that create the treatment atmosphere include all organic and inorganic compounds that can be vaporized. Among these, those that can be vaporized at room temperature and reduced pressure are preferred. More preferred are organic compounds having unsaturated bonds and polar groups, and inorganic compounds such as ammonia.

Preferred polar groups include carboxyl group,
Examples include an amino group and an epoxy group. Specifically, carboxyl group-containing monomers include acrylic acid, methacrylic acid, maleic acid, fumaric acid, tetrahydrophthalic acid, itaconic acid, citraconic acid, crotonic acid,
Unsaturated mono- and dicarboxylic acids such as isocrotonic acid and nadic acid (endocys-bicyclo[2,2°1]hept-1-ene-2,3-dicarboxylic acid) may be mentioned. Further examples include derivatives thereof, such as acid halides, amides, imides, anhydrides, esters, etc. Specifically, maleyl chloride, maleimide, maleic anhydride,
Similarly preferred are citraconic anhydride, monomethyl maleate, dimethyl maleate, glycidyl maleate, and the like.

Moreover, as the amino group-containing monomer, allylamine etc. are preferable.

Examples of epoxy group-containing monomers include aliphatic glycidyl esters or aliphatic glycidyl ethers such as glycidyl methacrylate, glycidyl acrylate, allyl glycidyl ether, vinyl glycidyl ether, glycidyl itaconate, and glycidyl maleate, and 2-cyclohexene-1-glycidyl ether. , cyclohexene-4,5-dicarboxylic acid diglycidyl ester, cyclohexene-4-carboxylic acid glycidyl ester, 5-
Norbornene-2-methyl-2-carboxylic acid glycidyl ester, endocis-bicyclo-[2,2,1]-5
Examples thereof include alicyclic glycidyl esters and alicyclic glycidyl ethers such as -hebutene-2,3-dicarboxylic acid diglycidyl ester.

Further, the electrode shape of the device may be either an internal electrode type or an external electrode type, and in the case of an external electrode type, either a capacitive type electrode or an inductive type electrode may be used.

Adding at least 4 or more oxygen atoms per 100 carbon atoms to the surface of a molded product can be achieved by appropriately selecting the treatment time and plasma irradiation amount depending on the compound and equipment used, but this can be done experimentally in advance. You can know.

A highly oriented polyolefin molded product is produced by reducing the rate of decrease in the intrinsic viscosity [η]p of a high molecular weight polyolefin having an intrinsic viscosity [η] of 3 dl/g or more as measured at 135°C in a decalin solvent to 14% or less. This is a method of manufacturing molded products by suppressing thermal degradation by heating the high molecular weight polyolefin during molding and heating time. After mixing the agent and an aliphatic hydrocarbon such as paraffin wax or a derivative thereof, an aliphatic hydrocarbon solvent, and a diluent such as liquid paraffin at a temperature below the melting point of the high molecular weight polyolefin, the mixture is heated to a temperature higher than the melting point of the high molecular weight polyolefin or above the melting point +100. If it is high molecular weight polyethylene, it is melt-kneaded at a temperature of 170 to 240 degrees Celsius, extruded from a die to extrude the undrawn yarn, preferably subjected to a draft of 10 to 30 degrees, then cooled and solidified, and then heated to a temperature near the melting point. It can be produced by stretching usually 10 times or more, preferably 15 to 30 times. The diluent can also be extracted from the molded article during or after stretching.

When melt-extruding high molecular weight polyolefin without using a diluent, especially when the intrinsic viscosity [η]m is 5 dIL/
When molding an ultra-high molecular weight polyolefin having a weight of 1.5 g or more, self-heating may occur and the intrinsic viscosity [η] may decrease. In addition, when mixing an ultra-high molecular weight polyolefin and a diluent, if the mixture is heated above the melting point of the ultra-high molecular weight polyolefin to form a mixed liquid with the diluent, even if a heat-resistant stabilizer is used in combination, the mixed liquid will deteriorate. This is not preferable since it may cause a decrease in molecular weight during storage.

The highly oriented polyolefin molded articles used in the method of the invention are, for example, in the form of filaments, tapes, nonwovens, and the like. Among these molded products, the elastic modulus is 2.
A stretched product of ultra-high molecular weight polyethylene with a tensile strength of 00 Pa or more, preferably 5° GPa or more, and a tensile strength of 1.2 GPa or more, preferably 1.5 GPa or more is lightweight, has high rigidity, high tensile strength, and has excellent weather resistance. Most suitable as a reinforcing material.

When using the plasma discharge treated highly oriented polyolefin molded product of the present invention as a composite material, if the drawn product is in the form of a filament, it can be processed into lobes, nets, cloth sheets, non-woven fabrics, and papers to achieve polarity as described below. If it is in the form of a tape, it can be processed into a cloth sheet, rope, etc. and used by being impregnated with or laminated with a polar material (described later), or by cutting the filament or tape as appropriate. A method of impregnating a polar material as a fibrous reinforcing material can be adopted.

Examples of polar materials to be bonded to the plasma discharge treated highly oriented polyolefin molded article of the present invention or impregnated with the molding material include cements such as Portland cement and alumina cement, A-203, Sin, 84C, T.
Inorganic polar materials such as ceramic materials such as iB2 and ZrBz, phenolic resins, epoxy resins, unsaturated polyester resins, diallyl phthalate resins, urethane resins,
Thermosetting resins such as melamine resin and urea resin, nylon, polyester, polycarbonate, polyacetal,
Examples include organic polar materials such as thermoplastic resins such as polyvinyl chloride, cellulose resins, polystyrene, and acrylonitrile-styrene copolymers. If it is below the softening point, the polyolefin molded product can be bonded by heating below the softening point. On the other hand, for polar materials exceeding the softening point of the polyolefin molded article, a method may be adopted in which the polyolefin molded article is impregnated with a solution in which the polar material is dissolved in an organic solvent or the like, and then the organic solvent is removed and dried.

(Effects of the Invention) The highly oriented polyolefin molded product of the present invention has significantly improved adhesion to polar materials compared to molded products subjected to conventional corona discharge treatment, etc., and the elasticity of the molded product is significantly improved. The retention rate of mechanical strength such as carbon fiber and tensile strength is usually 85% or higher, and in some cases it is 90% or higher, and there is almost no decrease in mechanical strength. If the product is combined into sports equipment such as rackets, skis, fishing rods, golf clubs, and bamboo swords, leisure equipment such as yachts, boats, and surfing boats, protective equipment such as helmets, and medical materials such as artificial joints and denture stands, etc. Mechanical strengths such as bending strength and bending elastic modulus are significantly improved.

In addition, in conventional methods, such as the method described in JP-A-60-146078, in order to obtain effective adhesion, one dose of irradiation is made weak so as not to cause a decrease in strength, and multiple irradiation doses (
In the examples, repeated irradiation was required (5 to 10 times), making the operation very complicated, whereas the method of the present invention has a sufficient effect of improving adhesion with just one irradiation. Even if the dose is large, there is no risk of a decrease in mechanical strength, so the tolerance range is wide and the operation is greatly simplified.

(Examples) Next, the present invention will be explained in more detail with reference to Examples, but the present invention is not limited to these Examples as long as the gist thereof is not exceeded.

Fire J mouth I± <Production of ultra-high molecular weight polyethylene multifilament> Intrinsic viscosity [η]: 8.20 dll/g, melting point = 1
Ultra-high molecular weight polyethylene powder (PE-I) 30 at 34°C
Weight % and paraffin wax (melting point = 69°C, molecular weight:
460) (7) Pulverized product (WAX-1) For 100 parts by weight of a mixture consisting of 70% by weight, heat stabilizer (3,5
-di-t-butyl-4-hydroxytoluene) 0.10
After adding parts by weight and mixing with a Henschel mixer, 20 m
Using a screw extruder with mφ and L/D: 20, the melt was melt-kneaded at a resin temperature of 190°C.
It was extruded from a die with an orifice diameter of 2 mm and solidified by air cooling. At this time, the diameter of the cooled and solidified fiber is 1.6 x 1
The debit was made so that the amount was 0-"m+a. That is,
Set the draft ratio to 3dl. It was set as 4. Subsequently, three Godetstrols were used in a stretching tank using n-decane as a heating medium (temperature inside the tank: 130°C) and stretching using triethylene glycol as a heating medium. (Tank temperature: 142°C) to produce a multifilament with a stretching ratio of 22 times. The physical properties of the obtained multifilament include the intrinsic viscosity [ηlp:
7.7dj! / g, reduction rate of intrinsic viscosity 6.1%
, a tensile modulus of elasticity of 85 GPa, a tensile strength of 2.30 Pa%, 1000 denier/100 fibers, and an added amount of oxygen atoms on the surface of 2.2/100 carbon atoms.

<Plasma discharge treatment of multifilament> ■ High-frequency plasma treatment equipment manufactured by Samco International Laboratories (
RFC-400), the ultra-high molecular weight polyethylene multifilament was heated to an output of too high and a degree of vacuum of 1.
The treatment was performed under OTorr and an acrylic acid gas atmosphere for a treatment time of 30 seconds. The tensile strength of the filament after treatment is
2.20Pa (retention rate 95.7%), tensile modulus 80
GPa (retention rate 94.0%), and the amount of oxygen atoms added on the surface was 16/100 carbon atoms.

(Manufacture of composite material) The above plasma discharge treated multifilament was mixed with two types of epoxy resins (tpoMtK@t:+oxMa).

and R-140, manufactured by Mitsui Petrochemical Industry Co., Ltd.), dicyanodiamide, 3-(p-chlorophenyl-1゜1-dimethylurea and dimethylformamide) at 57.4% each.
19. Impregnated with a resin mixed at a weight ratio of 6/3/3/17 and dried at 100°C for 10 minutes to prepare a prepreg, which was laminated and then press-molded at 100°C for 1 hour to form a unidirectional lamination. After producing the plate, the flexural strength and flexural modulus (JIS K 6911) of the laminate were measured. The results are shown in Table 1.

The ultra-high molecular weight polyethylene multifilament produced in Example 1 was subjected to plasma discharge treatment in the same manner as in Example 1 in an allylkaryamine gas atmosphere. The tensile strength of the filament after treatment is 2. IGPa (retention rate 91.3%), tensile modulus was 78GPa (retention rate 91.8%), and the amount of oxygen atoms added to the surface was 8/100 carbon atoms, and the amount of nitrogen atoms added was 5. carbon atoms/100 carbon atoms. Using this as a sample, a laminate was produced under the same conditions as in Example 1. The results are shown in Table 1.

Skin JL [Production of ultra-high molecular weight polyethylene multifilament] Intrinsic viscosity [ηIs: 17. Odx 7 g, melting point:
Ultra-high molecular weight polyethylene powder (P
E-II) 0.1 part by weight of a heat-resistant stabilizer (3,5-di-t-butyl-4-hydroxytoluene) was added to 100 parts by weight of a mixture consisting of 5% by weight and 95% by weight of decalin in a separator sealed with nitrogen. Pour into a bull flask and boil at 180 ml.
The mixture was stirred for 1 hour while heating at ℃ to obtain a homogeneous solution.

Next, the solution was put into a spinning tube and allowed to stand at a temperature of 180° C. for 2 hours under a nitrogen atmosphere to degas the solution. The solution was extruded into a coagulation tank (water bath) located 30 cm below a die plate having 100 capillaries with a diameter of 2 mm without applying a draft twice or more, to form a gel filament.

After this, the gel filament was continuously wound onto a 15 cm diameter bobbin at a speed of 1 m/min. The bobbin of the gel filament was immersed in n-hexane at room temperature to replace decalin, the liquid component of the gel, with n-hexane.

This gel fiber was returned to its original state and n-hexane was evaporated at 50°C to 60°C. The dry fiber was 1300±100 denier. Place 50cm of dry fiber in a heat tube sealed with nitrogen.
Three-stage stretching was performed using four Godets rolls at a speed of 1/min. The effective length of each heat tube is 50 cm, and the temperature inside the first heat tube is 110°C and the temperature inside the second heat pipe is 130°C.
The temperature inside the third heating tube was 140°C. The stretching ratio is the first
Determined by the rotation ratio of the Godet roll and the 4th Godet roll,
The stretching ratio at this time was 60 times. The rotational speeds of the second and third godet rolls were appropriately selected within a range that allowed stable operation.

The physical properties of the obtained multifilament are the intrinsic viscosity [ηlp
: 14.0dfL/g, rate of decrease in limiting viscosity 17
．． 6%, tensile modulus 80GPa, tensile strength 2.5GPa
The fibers were 2100 denier/100 fibers, and the amount of oxygen atoms added to the surface was 2.5/100 carbon atoms.

Production of composite agent> The ultra-high molecular weight polyethylene multifilament produced in Comparative Example 1 was subjected to plasma discharge treatment under the same conditions as in Example 1. The tensile strength of the filament after treatment is 1.5GP
a (retention rate 60%), and the tensile modulus was 65 GPa (retention rate 81%).

Also, the amount of oxygen atoms added to the surface is! The number of carbon atoms was 2/100 carbon atoms. Using this as a sample, a laminate was produced under the same conditions as in Example 1. The results are shown in Table 1.

Claims (3)

[Claims] (1) Intrinsic viscosity [η
]_m is 3 dl/g or more of high molecular weight polyolefin,
A highly oriented polyolefin molded product obtained by molding the product under conditions where the rate of decrease in its intrinsic viscosity [η]_p is 14% or less is placed in a gas atmosphere containing a volatile organic compound and/or inorganic compound. A method for producing a polyolefin molded article with improved adhesiveness, characterized by subjecting it to plasma discharge treatment. (2) A polyolefin molded product subjected to plasma discharge treatment has at least 4 oxygen per 100 carbon atoms on its surface.
The manufacturing method according to claim (1), wherein at least one is added. (3) The volatile organic compound and/or inorganic compound is
The method according to claim 1, wherein the monomer contains a carboxyl group and/or an amino group.