JPH03137295A - Lubricant for pigment-coated paper - Google Patents

Abstract

PURPOSE:To provide the subject lubricant useful as lubricant, dusting preventing agent, mold-releasing agent, blocking-preventing agent, etc., by comprising the aqueous dispersion of a specific low molecular weight PE modified product. CONSTITUTION:The objective lubricant comprises the aqueous dispersion of a low molecular weight PE modified product having a penetration of >=20dmm, preferably >=60dmm, an acid value of 3-80mg KOH/g, preferably 6-20mg KOH/g, a density of <=0.99g/cc, preferably <=0.90g/cc, a molting point of preferably <=100 deg.C, a melt-viscosity of preferably <=100cPs at 150 deg.c and a mol. weight of preferably <=2000.

Description

Detailed Description of the Invention [Industrial Application Field] The present invention relates to a lubricant for pigment-coated paper, and more specifically to a lubricant for pigment-coated paper for lubrication and mold release in the production of pigment-coated paper. Regarding.

[Prior Art] Conventionally, higher fatty acid metal salts such as calcium stearate and those having a penetration of lodmm or less have been used as lubricants in the production of coated paper such as offset paper, gravure paper, paperboard or cast coated paper coated with pigments. , the acid value is about 12 to 30 mg KOf (/gr and the density is about 0.93
Aqueous dispersions of low molecular weight polyethylene modifications of ~0.99 gr/cc have primarily been used. It is also known to use paraffin wax, liquid hydrocarbon oil, higher fatty acids, higher alcohols, higher fatty acid metal salt oils, aliphatic phosphoric acid esters, polyalkylene glycols or derivatives thereof, or aqueous dispersions thereof.

[Problems to be Solved by the Invention] However, these lubricants still have a weak release effect and anti-dusting effect. Hang or coated paperboard 1
There was a problem in that dusting could not be completely suppressed during gloss calendering performed at a high temperature of 20 to 160°C. In addition, when manufacturing cast-coated paper using these lubricants, whether by direct casting, gelling casting, or wet casting, increasing the operating speed in order to improve productivity will improve the efficiency of the cast drum. This caused drum picks and even poor mold release.

When these calenders or drums become contaminated, there is a problem in that operations often have to be stopped and the calender rolls or drums must be cleaned. To deal with these problems, increasing the amount of lubricant added can improve the situation a little, but it is not satisfactory, and the paper may become too slippery.
This tends to cause deterioration in printability.

[Means for Solving the Problems] The present inventors have developed a lubricant that has superior mold release and dusting prevention effects in calenders or cast drums and enables long-term continuous operation compared to conventional lubricants. As a result of extensive research, we have arrived at the present invention.

That is, the present invention provides a lubricant for pigment-coated paper comprising an aqueous dispersion of a modified low-molecular-weight polyethylene having a penetration degree of 204 mm or more, an acid value of 3 to 80 mgK, and a density of 0.99 gr/cc or less. and a lubricant for pigment-coated paper comprising an aqueous dispersion of the modified low-molecular-weight polyethylene and polyether-modified silicone oil.

[Structure and operation of the invention] Low molecular weight polyethylene modified products (hereinafter referred to as low molecular weight polyethylene modified products) that can be used in the lubricant for pigment-coated paper of the present invention include low molecular weight polyethylene modified products produced by various manufacturing methods. Oxide obtained by oxidizing molecular weight polyethylene using various oxidation methods,
Thermal and oxidative decomposition products of medium to high molecular weight polyethylene, ethylenically unsaturated carboxylic acid graft polymers of low molecular weight polyethylene, or copolymers of ethylene and ethylenically unsaturated carboxylic acids and, if necessary, other unsaturated monomers. etc. can be used. The polyethylene used in the production of the low molecular weight polyethylene modified product may be either polyethylene obtained by polymerizing ethylene at high temperature and high pressure using a radical catalyst, or polyethylene obtained by polymerizing ethylene at low pressure using a Ziegler catalyst. The low molecular weight polyethylene modified product is
These polyethylenes are obtained by oxidizing or oxidatively decomposing them using air, oxygen, ozone, or other various oxidizing agents.

Ethylenically unsaturated carboxylic acids constituting unsaturated carboxylic acid graft polymers of low molecular weight polyethylene or copolymers of ethylene and ethylenically unsaturated carboxylic acids include (meth)acrylic acid (γ7-lyric acid and methacrylic acid), maleic acid, fumaric acid, itaconic acid, and ethylenically unsaturated mono- or polycarboxylic acids. In addition, unsaturated monomers having functional groups that can be derived into carboxyl groups by hydrolysis as ethylenically unsaturated carboxylic acids, such as unsaturated monomers containing carboxylic anhydride groups [maleic anhydride, itaconic anhydride, etc.] , alkyl ester of ethylenically unsaturated carboxylic acid [
Methyl (meth)acrylate, ethyl (meth)acrylate, etc.], nitrile group-containing unsaturated monomers ((meth)acrylonitrile, etc.), etc. can be polymerized and hydrolyzed and used. Among these, preferred ones are graft polymers or copolymers that can be easily obtained (
These are meth)acrylic acid, maleic acid, and maleic anhydride. Other unsaturated monomers that can be copolymerized if necessary include alkyl esters of ethylenically unsaturated carboxylic acids [propyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, stearyl (meth)acrylate, etc.]; Ethylenically unsaturated alcohol [
(meth)allyl alcohol, hydroxy (meth)acrylate, diethylene glycol mono (meth)acrylate, poly-oxyethylene-oxypropylene glycol mono (meth)acrylate, glycerin mono
(meth)acrylate, etc.], ether group-containing ethylenically unsaturated monomers [poly-oxyethylene-oxypropylene glycol mono (meth)allyl ether, etc.],
Ethylenically unsaturated monomers containing amide groups [acrylamide, N-methylacrylamide, etc.], esters of ethylenically unsaturated alcohols [vinyl acetate, (meth)allyl acetate, etc.], ethylenically unsaturated monomers containing aldehyde groups [
[acrylic aldehyde, etc.], or hydrocarbon-based ethylenically unsaturated monomers [styrene, propylene, butene, vinyl chloride, etc.].

The penetration degree of the modified low molecular weight polyethylene is 206 mm or more, preferably 4Qdmm or more, more preferably 6Qdmm.
mm or more. If the penetration is 20 dmm and no droplets are present, good mold release and dusting prevention effects cannot be obtained.

The acid value of the modified low molecular weight polyethylene is 3 to 80 mgK.
OH/g, preferably 5 to 30 mg KO-H/g, more preferably 6 to 20 mg KDH/g. Acid value is 3m
If it is less than gKOfl/8, a fine particle emulsion with good stability cannot be obtained, and if it exceeds 80mg/KOfl/g, the mold release and dusting prevention effects will be reduced.

The density of the modified low molecular weight polyethylene is usually 0°99g.
/cc or less, preferably 0.93 g/cc or less, more preferably 0.90 g/cc or less. Melting point is usually 14
The temperature is 0°C or lower, preferably 110°C or lower, and more preferably 100°C or lower. Melt viscosity is usually 4 at 150℃
000 cps or less, preferably 1000 cps or less, and more preferably 100 cps or less. The molecular weight is usually 10,000 or less, preferably 5,000 or less, and more preferably 2,000 or less. The lower the density, melting point, melt viscosity, and molecular weight of the modified low-molecular-weight polyethylene, the better the mold release and dusting prevention effects tend to be.

Examples of the salt or partial salt of the modified low molecular weight polyethylene include ammonia, alkylamine [monoethylamine,
monobutylamine, dibutylamine, tributylamine, etc.], alkanolamines [monoethanolamine,
Amine compounds such as ethylenediamine and polyethylene polyamine (diethylenetriamine, triethylenetetramine, etc.), group II metals of the periodic table (lithium, sodium, potassium, etc.), group II metals [magnesium, [calcium, zinc, etc.], group ■ metals [aluminum, etc.], or group ■ metals [iron, cobalt, nickel, etc.]
Salts such as

Preferred among these salts are ammonia, monoethanolamine, jetanolamine, triethanolamine, lithium, sodium, potassium, magnesium, calcium and zinc salts. As for these salts, a part of the acid value of the modified low molecular weight polyethylene may be a salt, or all of the acid value may be a salt.

Examples of the polyether-modified silicone oil that may be blended if necessary include the polyether-modified silicone oil represented by formula (1), which has water solubility, water dispersibility, or self-emulsifying property, and has an aqueous solution cloud point of usually 20. ℃ or higher, preferably 50℃ or higher. Ethylene oxide and propylene oxide may be a random copolymer or a block copolymer.

[However, xSy is an integer of 1 to 100, L is an integer of 5 to 100, m is an integer of 0 to 50, and R is a C1 to C22 alkyl group. ] As the emulsifying and dispersing agent for the low molecular weight polyethylene modified product,
Nonionic surfactant [polyoxyethylene alkyl phenyl ether (usually 4 to 70 mol of ethylene oxide,
(preferably 5 to 20 moles of adduct), polyoxyethylene alkyl ether (usually 4 to 70 moles of ethylene oxide, preferably 5 to 20 moles of adduct), polyoxyethylene alkyl ester (usually 4 to 7 moles of ethylene oxide)
0 mol, preferably 0 to 25 mol of polyethylene glycol (mono-, diester), polyhydric alcohol fatty acid ester ethylene oxide adduct (monostearylglyceride ethylene oxide adduct, etc.), fatty acid amide ethylene oxide adduct, higher alkylamine ethylene oxide adduct 7-4 surfactants; [Alkylbenzene sulfonates such as sodium dodecylbenzene sulfonate, α-olefin sulfonates such as sodium hexadecene sulfonate,
N-methyl N-oleyl taurine, dialkyl sulfosuccinates such as sodium di-2-ethylhexyl sulfosuccinate, alkyl sulfonates such as sodium tetradecyl sulfonate, sodium hexadecyl sulfonate, sodium petroleum sulfonate, α-sulfopalmitic acid α-Sulfo fatty acid salts such as sodium, sulfonate type anionic surfactants such as polyoxyethylene styrenated phenyl ether sulfonates and naphthalene sulfonate formalin condensates with a condensation degree of 2 to 12, potassium stearyl sulfate, etc. Sulfate type anionic surfactants such as alkyl sulfate salts of , sulfated oil salts such as sulfated castor oil, fatty acid sulfate salts such as polyoxyethylene alkyl ether sulfate salts and stearyl alcohol sulfate sodium salts, oleic acid Fatty acid salt type anionic surfactants such as potassium and sodium stearate, phosphate ester type anionic surfactants such as phosphate ester salts of higher alcohol ethylene oxide adducts], amphoteric surfactants [amino acid type amphoteric surfactants, etc. carboxylate type amphoteric surfactants, sulfate ester salt type amphoteric surfactants, sulfonate salt type amphoteric surfactants, phosphate ester salt type amphoteric surfactants, etc.] or water-soluble polymers [carboxymethyl cellulose, 1 -) polycarboxylic acid salts such as IJum salt, hydroxyethylcellulose, casein, sodium alginate, polyvinyl alcohol, and sodium polyacrylate]. Among these, preferred are polyoxyethylene alkyl phenyl ether (adduct of 5 to 20 moles of ethylene oxide), polyoxyethylene alkyl ether (adduct of 5 to 20 moles of ethylene oxide),
20 mole adduct), polyhydric alcohol fatty acid ester ethylene oxide adduct, sodium dodecylbenzene sulfonate, sulfosuccinic acid di-2-ethylhexyl ester sodium salt, sodium petroleum sulfonate, potassium oleate, sodium stearate, degree of condensation 2-12
sodium naphthalene sulfonate, phosphate ester salt of higher alcohol ethylene oxide adduct, and amino acid type amphoteric surfactant.

The proportion of the emulsifying and dispersing agent used is at least one selected from nonionic surfactants, gamma ion surfactants, amphoteric surfactants, and water-soluble high 6% per 100 parts by weight of the modified low molecular weight polyethylene. Emulsifying dispersant is 0.5-10
0 parts by weight, preferably 3 to 50 parts by weight, more preferably 6 to 30 parts by weight.

If it is less than 0.5 parts by weight, a stable emulsified dispersion cannot be obtained;
If the amount exceeds 0.00 parts by weight, mold release, anti-dusting effects, and water resistance will deteriorate.

The proportion of polyether-modified silicone oil used is 100 parts by weight per 100 parts by weight of the low molecular weight polyethylene modified product.
It is not more than 50 parts by weight, more preferably not more than 10 parts by weight. If it exceeds 100 parts by weight, foaming will increase and ink receptivity will decrease, which is not preferable.

The production of the aqueous dispersion of the modified low molecular weight polyethylene includes:
Either water, the modified low molecular weight polyethylene and the emulsifying dispersant are placed in a reaction vessel, heated above the melting point of the modified low molecular weight polyethylene, emulsified and dispersed by stirring, and then cooled. Add water or hot water to the molten mixture under stirring, emulsify and disperse, and then cool.
A molten mixture of the modified low molecular weight polyethylene and the emulsifying and dispersing agent is poured into water heated to a temperature above the melting point of the modified low molecular weight polyethylene, and the mixture is cooled after being emulsified and dispersed. This can be easily carried out by adding water to a highly concentrated (60% or more) aqueous dispersion of a molten mixture of a modified low-molecular-weight polyethylene and an emulsifying dispersant while stirring and cooling.

The polyether-modified silicone oil may be added before emulsifying and dispersing the low molecular weight modified polyethylene, or may be added after emulsifying and dispersing the low molecular weight modified polyethylene and uniformly dispersed.

In addition, the lubricant for pigment-coated paper of the present invention may contain or be mixed with an antioxidant, an ultraviolet absorber, a water-resistant agent, a preservative and fungicide, an insecticide, a fungicide, an antifoaming agent, a fragrance, a dye, or a pigment. May be used.

The physical properties of the modified low molecular weight polyethylene in the present invention were measured using the following method.

Penetration: According to the penetration test method specified in JIS K-2235-1980. However, the measurement temperature is 25℃, the needle,
The total weight of the holder and weight is 1. OOgr, entry time was measured at 5 seconds.

Acid value: Sample W gr was dissolved under the boiling point of toluene, and phenolphthalein water and methanol 1:
Using a 1% solution of 1, JIS K-2501-1980
Titrate with the specified N/10 potassium hydroxide standard isopropyl alcohol solution, and the N/1 when the pale pink color lasts for 30 seconds.
The titration amount A- of a standard isopropyl alcohol solution of potassium hydroxide was measured, and the acid value was determined from the following formula.

However, N: Normality of N/10 potassium hydroxide standard isopropyl alcohol solution B: Amount of N/10 potassium hydroxide standard isopropyl alcohol solution required for titration in blank test (7) Density: According to ASTM D-1505.

Melting point: According to JIS K-2523.

Melt viscosity Measured at 150°C using a Nibruck field viscometer.

Molecular weight: Displayed as number average molecular weight by GPC.

[Examples] The present invention will be further described below with reference to Examples, but the present invention is not limited thereto. In addition, % in the examples
indicates weight %.

Table 1 shows the contents of the modified low molecular weight polyethylene used in Examples 1 to 5 and Comparative Examples 1 to 4.

Table 1 Contents of modified low molecular weight polyethylene 7 8 Example 1 In a reaction vessel, 237 gr of the modified low molecular weight polyethylene described in Example 1 in Table 1 and 1°52 gr of sodium hydroxide were added.
, polyoxyethylene monooleate (adduct with 10 moles of ethylene oxide) 39, Igr, polyoxyethylene nonylphenyl ether sulfate sodium salt (adduct with 6 moles of ethylene oxide) 30% aqueous solution 9
．． 3 gr and water 472. Prepare Igr and heat to 120℃
After stirring for 2 hours, it was cooled to 40°C to form a pale yellowish white liquid.
An aqueous dispersion with a concentration of 40% was obtained.

Example 2 In a reaction vessel, 266, 6g of the low molecular weight polyethylene modified product described in Example 2 in Table 1, 2g of sodium hydroxide, and Ig
r, 1.8 g of a 25% aqueous solution of ammonium hydroxide, 41.3 gr of octahelyoxyethylene nonylphenyl ether (8.5 mole adduct of ethylene oxide), 13.5 gr of a 70% aqueous solution of sodium dodecylbenzenesulfonic acid salt, and 474 gr of water. ．． 7 gr was charged, heated to 100°C, stirred for 1 hour, and then cooled to 40°C to obtain a pale yellowish white aqueous dispersion with a concentration of 40%.

Example 3 In a reaction vessel, 260.8g of the low molecular weight polyethylene modified product described in Example 3 in Table 1 and 2.4g of sodium hydroxide were added.
r, zinc chloride 0.95 gr, sorbitan stearic acid monoester ethylene oxide 10 mole adduct 29.
5gr, N-methyl-N-oleyl taurine 11.8
gr and 478.5 gr of water, heated to 100°C, stirred for 1 hour, then cooled to 40°C to give a pale yellowish white color with a concentration of 40%.
An aqueous dispersion of was obtained.

Example 4 266, 9g of the low molecular weight polyethylene modified product described in Example 4 in Table 1 and 3.2g of potassium hydroxide were placed in a reaction vessel.
r, lithium chloride O, [igr, polyoxyethylene stearyl ether (ethylene oxide 10 mole adduct)
47.7 gr, petroleum sulfonic acid sodium salt (CI2
) 3.2 gr and water/478.5 gr, 1
After heating to 00°C and stirring for 1 hour, the mixture was cooled to 40°C to obtain a pale yellowish white aqueous dispersion with a concentration of 40%.

Example 5 In a reaction vessel, 253.2 gr of the low molecular weight polyethylene modified product described in Example 5 in Table 1 and 2.6 g of sodium hydroxide were added.
r, calcium hydroxide 0.87gr, polyoxyethylene nonylphenyl ether (6 moles of ethylene oxide adduct) 25JgrJ polyoxyethylene nonylphenyl ether (18 moles of ethylene oxide adduct) 25
．． 3 gr, 24 gr of 50% aqueous solution of sulfosuccinic acid di-2-ethylhexyl ester sodium salt.

The polyether-modified silicone oil represented by (Formula I) described on page 10 of the specification of this application (however, X-20, y=1
0, L=10, m=2, R-propyl group) and 487.0 gr of water were heated to 100°C and stirred for 1 hour, then cooled to 40°C to form a pale yellowish white aqueous dispersion with a concentration of 40%. I got it.

Example 6 In a reaction vessel, 281.6g of the low molecular weight polyethylene modified product described in Example 6 in Table 1, 15g of sodium hydroxide, and I
gr, polyoxyethylene stearyl ether (ethylene oxide 12 mole adduct>30.Igr and water 50
After charging 3gr and heating to 100℃ and stirring for 2 hours,
The mixture was cooled to 0.degree. C. to obtain a pale yellowish white liquid aqueous dispersion having a concentration of 40%.

Comparative Example 1 In a reaction vessel, 284.8 gr of the oxidized type low molecular weight polyethylene modified product described in Comparative Example 1 in Table 1, 3.25 gr of sodium hydroxide, and polyoxyethylene oleyl ester (
10 mole ethylene oxide adduct) 39.1. gr.

Polyoxyethylene nonylphenyl ether sulfate sodium salt (ethylene oxide 4 mole adduct) 30
% aqueous solution and 469.3 gr of water,
After heating to 120°C and stirring for 2 hours, the mixture was cooled to 40°C to obtain a pale yellowish white aqueous dispersion with a concentration of 40%.

Comparative Example 2 In a reaction vessel, 260.8 gr of the oxidized type low molecular weight polyethylene modified product described in Comparative Example 2 in Table 1, 17.3 gr of sodium hydroxide, and polyoxyethylene nonylphenyl ether (8.5 mol ethylene oxide adduct) were added. 5
gr, 7 of sodium dodecylbenzenesulfonate
13.3g of 0% aqueous solution and 468.3g of water were charged, heated to 120°C, stirred for 2 hours, and then cooled to 40°C to obtain a pale yellowish white aqueous dispersion with a concentration of 40%.

1 2 Comparative Example 3 In a reaction vessel, 268.8 gr of the oxidized low molecular weight polyethylene modified product described in Comparative Example 3 in Table 1, 0.29 gr of sodium hydroxide, and polyoxyethylene nonylphenyl ether (adduct of 8.5 moles of ethylene oxide) were added. 4.1.
6gr, sodium dodecylbenzenesulfonate 7
13.7g of 0% aqueous solution and 466.3g of water were charged, heated to 120°C, stirred for 2 hours, and then cooled, but an unstable dispersion of large particles was obtained. Although we conducted emulsification studies using various emulsifying dispersants, we were unable to create a stable aqueous dispersion.

Comparative Example 4 Comparative Example 4 was a commercially available aqueous calcium stearate dispersion.

Test Example 1 - Distribution The lubricants 1 to 6 for pigment-coated paper produced according to the present invention and those of Comparative Examples 1.2 and 4 were tested for dusting test, release test, physical properties of pigment coating liquid, and physical properties of coated paper. The results are shown in Tables 2 and 3.

(1) Dusting test, measurement of physical properties of coated paper Pigment coating liquid (J, solid content, No. in parts by weight, 1 pre-dispersed clay (8M0 company, IIW-90) 40 parts,
N.

2 Predispersed clay (8M0, 11T clay) 50 parts, light calcium carbonate (Okutama Kogyo ■, Tama Pearl TP-22211> 10 parts, polyacrylic acid dispersant (San Nopco ■, SN Dispersant 5040)
) 0.2 parts, sodium hydroxide 0.3 parts, carboxy-modified alkali thickened latex (Japan Synthetic Rubber ■, JS
R0628) 7 parts, 62% solids consisting of 0 or 1.2 parts of lubricant, color PII 9. This is a dispersion liquid of O for gravure coated paper.

The coated paper was prepared by coating medium-quality paper (64 gr/m2) with an edge coater at 600 m/min and drying at 150°C for 30 seconds. The coating amount is 13 gr/m2.

The dusting test was performed using the above coated paper at a temperature of 70℃ and a linear pressure of 1
The paper was passed through a 50 kg/cm super calender, and the dirt on the chilled roll surface was visually judged and evaluated on a 10-point scale (10 good to 1 bad).

The physical properties of the coated paper are as follows:
The evaluation was performed using paper that had been passed twice through a super calendar of /cm. The results are shown in Table 2.

(2) Release test, measurement of physical properties of coated paper The pigment coating liquid was based on the formulation for cast coated paper.
1 Pretice Hearst Clay (ull-90) 85 parts, heavy calcium carbonate (Sankyo Seifun ■, Niscalon #1
500) 15 parts, polyacrylic acid dispersant (SN Dispersant 5040) 0.2 parts, sodium hydroxide 0.05 parts, ammonium casein 6 parts, SBR latex (Japan Synthetic Rubber, JSR0696) 12 parts, and lubricant. It is a dispersion with a solids content of 45% and a color pH of 9.0, consisting of 0 or 1 part.

For the mold release test, the above pigment coating liquid was applied to foam paper (64gr/m2) using a No. 22 bar coater, and the temperature was 130°C.
After drying for 7 seconds at
The paper was passed through a chrome-plated, mirror-finished super calendar with a linear pressure of 100 kg/cm, and after 2 seconds of passing through the nip, the peel strength of the coated paper stuck to the delt roll from the chilled roll surface was measured using a tensile strength measuring machine. This was done by measuring. In addition, the stain on the chilled roll surface after peeling was visually evaluated.

The physical properties of the coated paper were also evaluated for the resulting highly glossy cast coated paper. The results are shown in Table 3.

5 6 [Effects of the Invention] As is clear from the above test examples, the lubricant for pigment-coated paper of the present invention is extremely excellent in preventing dusting in super calenders, gloss calenders, etc., and as a release agent for cast coated paper. This makes it possible to extend continuous operation time and speed up operation speed, improving productivity and reducing paper production costs. It also improves the quality of the paper, with the effect of improving gloss being observed.

Due to the above effects, the lubricant for pigment-coated paper of the present invention can be used as a lubrication, anti-dusting, mold release agent or anti-blocking agent for the coating liquid of pigment-coated paper. It is useful as a smoothing agent, water repellent, mold release agent for ceramics, cement, and building materials, and as a lubricant.

The amount of lubricant added in these applications is usually 0.01 to 10% by weight based on the solid content of the coating composition.

9

Claims (1)

[Claims] 1. Penetration is 20 dmm or more, and acid value is 3 to 80 mg KO.
H. A lubricant for pigment-coated paper comprising an aqueous dispersion of a modified low molecular weight polyethylene having a density of 0.99 gr/cc or less. 2. Penetration is 20dmm or more, acid value is 3-80mgKO
H. A lubricant for pigment-coated paper comprising an aqueous dispersion of a low molecular weight polyethylene modified product having a density of 0.99 gr/cc or less and a polyether modified silicone oil. 3. The low molecular weight polyethylene modified product is an oxide of low molecular weight polyethylene, an oxidative decomposition product of medium to high molecular weight polyethylene, a graft polymer of low molecular weight polyethylene with ethylenically unsaturated carboxylic acid, or ethylene and ethylenically unsaturated carboxylic acid. The lubricant according to claim 1 or 2, wherein the lubricant is one or more selected from copolymers with and optionally other unsaturated monomers. 4. The low molecular weight polyethylene modified product contains ammonia, an amine compound, Group I, Group II, Group III or Group III of the periodic table.
The lubricant according to any one of claims 1 to 3, which is a salt or partial salt of at least one group IV metal.