A greasing process for furniture leather

Abstract

The present application relates to the field of furniture leather processing, and more particularly to a greasing process for furniture leather. The greasing process for furniture leather comprises, in sequence: rinsing → chrome retanning → water washing and neutralization → dyeing / greasing → water washing, drum drying. On the one hand, the preparation process of the present application utilizes a relatively stable greasing agent, which reduces volatilization and oxidation of the greasing agent during use, thereby reducing the VOC (Volatilization Oxide) value and atomization value released by the leather and improving the leather's oxidation resistance. On the other hand, during the dyeing / greasing step, the acrylate retanning agent, dicyandiamide, and melamine form a protective film on the surface of the leather embryo that has good adhesion to the leather embryo, filling small holes and defects on the leather surface and reducing the leather's contact with oxygen. Furthermore, the VOC value and atomization value of the prepared leather are reduced, and the oxidation resistance of the leather is improved.

Description

Technical Field

[0001] The present application relates to the field of furniture leather processing, and in particular to a greasing process for furniture leather. Background Art

[0002] With the improvement of people's living standards, furniture leather is growing in popularity. Fatliquor is an essential step in the leather processing process, which has a significant impact on the sensory properties of leather products, the VOC value, atomization value and mechanical properties of leather. However, the fatliquors used in the traditional fatliquor process are generally synthetic oils (mineral oil, paraffin oil, fatty acid esters), plant oils (palm oil, lecithin), animal oils (fish oil, neat's foot oil), etc., which are easy to obtain and cost-effective. However, these traditional leather fatliquors themselves have an unpleasant odor. For example, sulfited fish oil has a fishy smell. Moreover, they are easy to volatilize during the use of leather, causing the leather to harden during use and be easily oxidized, resulting in discoloration, cracking, and a poor feel. Summary of the Invention

[0003] The present application solves the problems that leather prepared by the traditional leather fatliquor process has an unfriendly odor, insufficient oxidation resistance, and a fatliquor that is easily volatile during use. The present application provides a fatliquor process for furniture leather.

[0004] The present application provides a greasing process for furniture leather.

[0005] A greasing process for furniture leather comprises the following steps in sequence:

[0006] Rinsing: The embryo skin is treated with a rinsing liquid at a temperature of 45-60° C. and a rotation speed of 2-12 r / min for 10-30 minutes to prepare a first preform, and then the liquid is drained; the rinsing liquid is composed of 0.3-1.5% fatty alcohol polyoxyethylene ether, 0.3-1.5% ethoxylated fatty alcohol, 0.2-1% oxalic acid and 300-500% water based on the mass of the embryo skin;

[0007] Chrome retanning: treating the first preform with a chrome retanning solution at a temperature of 40-60° C. and a rotation speed of 2-12 r / min for 10-60 minutes; then adding 0.2-1.5% sodium formate and 0.2-1.5% baking soda, and continuing the treatment for 5-30 minutes to prepare a second preform; the chrome retanning solution comprises 1-10% chrome powder, 0.5-4% protein filler, 0.2-2% polyurethane fatliquor, and 200-300% water;

[0008] Washing and neutralizing: placing the second preform in a mixture of 200-400% water, 0.5-2.5% neutralized tannin, and 0.2-1.5% sodium formate, at 35-55° C. and a rotation speed of 2-12 r / min for 5-20 minutes; then adding 0.2-1.8% baking soda and treating for 5-30 minutes; then adding 0.5-2.5% acrylate retanning agent and treating for 5-40 minutes to prepare a third preform, and then draining;

[0009] Dyeing / fatliquoring: placing the third preform in a mixture of 2-16% acrylic retanning agent and 100-200% water, treating at a temperature of 35-55° C. and a rotation speed of 2-12 r / min for 5-30 minutes, adding a dye retanning agent composition, and treating for 5-20 minutes; then adding a fatliquoring composition, treating for 10-80 minutes, to prepare a fourth preform, and then draining the preform; the dye retanning agent composition comprises 1-8% dicyandiamide, 1-8% melamine, 1-8% disperse tannin, 2-20% tannin extract, 1-8% white tannin, and 1-6% dye; the fatliquoring composition comprises 1-10% polyurethane acrylate fatliquoring agent;

[0010] Washing, drum-drying: The fourth preform is washed, drained, drum-dryed, and dried to obtain furniture leather.

[0011] By adopting the above technical solution, furniture leather with low VOC, low fogging value, good stability, environmental protection and no odor is prepared.

[0012] On the one hand, the preparation process of the present application uses a relatively stable fatliquor, which reduces the volatilization and oxidation of the fatliquor during the use of the leather, thereby reducing the VOC value and atomization value released by the leather and improving the oxidation resistance of the leather.

[0013] On the other hand, the acrylate retanning agent, dicyandiamide and melamine in the dyeing / fatting step form a protective film on the surface of the leather embryo that has good bonding with the leather embryo. The protective film can well cover the leather fibers, improve the toughness and stability of the leather, fill the small holes and defects on the leather surface, reduce the volatilization of small molecules in the leather embryo, reduce the VOC value and atomization value, reduce the contact of the leather with oxygen, and improve the gloss, flatness, strength, yellowing resistance, anti-fouling and waterproof functions of the leather surface, making the prepared furniture leather more stable. Furthermore, the VOC value and atomization value of the prepared household leather are reduced, and the oxidation resistance is improved.

[0014] Acrylate retanning agent, disperse tannin and white tannin (methylene bonded phenolsulfonic acid condensate) are used in combination. Dispersed tannin promotes the dispersion of dicyandiamide, melamine, tannin and dyes; white tannin slows down the combination of dicyandiamide, melamine, tannin and leather embryo, promoting penetration; acrylate retanning agent promotes the penetration of dicyandiamide, melamine and tannin into leather embryo. The combination of acrylate retanning agent, disperse tannin and white tannin improves the filling of dicyandiamide, melamine and tannin in leather embryo, improves the fullness and firmness of leather, reduces the VOC value and atomization value of leather, reduces the contact of leather with oxygen, and thus improves oxidation resistance; at the same time, disperse tannin, white tannin, acrylate retanning agent are used in combination with dicyandiamide and melamine to improve the uniformity of the protective film formed on the leather embryo surface and has better bonding with the leather embryo, thereby improving the wear resistance and rubbing color fastness of leather.

[0015] Preferably, in the rinsing step, after the rinsing liquid is treated, 0.3-1.2% of formic acid is added and then treated for 10-90 minutes.

[0016] By adopting the above technical scheme, formic acid works synergistically with fatty alcohol polyoxyethylene ether, ethoxylated fatty alcohol and oxalic acid to further deash and soften the leather embryo; at the same time, formic acid can easily penetrate into the leather embryo, causing the leather embryo to swell appropriately, promoting the subsequent chrome retanning step, so that chrome powder and protein fillers can better penetrate into the leather embryo, thereby improving the fullness, grain smoothness, softness, bendability, wear resistance and durability of the leather.

[0017] Preferably, in the chrome retanning step, after the addition of sodium formate and baking soda, 0.2-1.4% of baking soda is continued to be added for a second baking soda treatment for 5-30 minutes; then 0.2-1.3% of baking soda is added for a third baking soda treatment for 10-60 minutes.

[0018] By adopting the above technical solution, baking soda is added multiple times to promote the binding of chromium molecules with skin collagen without making the pH too high, thereby reducing the binding of chromium with the skin embryo.

[0019] Multiple treatments with baking soda are used in combination with acrylate retanning agents, dispersed tannins and white tannins to further improve the fullness, softness, flexibility, wear resistance and durability of the prepared household leather.

[0020] Preferably, in the chrome retanning step, after the third treatment with baking soda, the drum is stopped overnight, and the next day, the drum is treated for 5-10 minutes at a rotation speed of 2-12 r / min and the liquid is drained.

[0021] By adopting the above technical solution, the combination of chromium molecules and leather collagen is further promoted, thereby improving the fullness, softness, flexibility, wear resistance and durability of the leather.

[0022] Preferably, in the dyeing / fatliquoring step, the acrylic retanning agent consists of 1-8% of acrylic ester with an average molecular particle size of 50-100 nm and 1-8% of acrylic polymer retanning agent with an average molecular particle size of 100-400 nm.

[0023] By adopting the above technical solution, the acrylic acid retanning agent is used in combination with an acrylic acid polymer retanning agent with a larger average molecular particle size and an acrylic acid ester retanning agent with a smaller average molecular weight particle size. The small molecules can penetrate into the smaller gaps inside the leather embryo protein fibers, thereby improving the tanning effect on the leather embryo, and improving the bonding strength between the protective film formed on the surface of the leather embryo by the acrylic acid ester retanning agent, dicyandiamide and melamine and the leather embryo, thereby better filling the small holes and defects on the surface and inside of the leather; the acrylic acid ester retanning agent and the acrylic acid polymer retanning agent have greater compatibility, further reducing the volatilization of small molecular substances in the leather embryo, lowering the VOC value and the fogging value, and reducing the contact of the leather embryo with oxygen, thereby improving the glossiness, flatness, strength, yellowing resistance, stain resistance and waterproof function of the leather surface, and making the prepared furniture leather more stable.

[0024] Preferably, in the dyeing / fatting step, the fatliquor composition further comprises 1-10% polyurethane.

[0025] By adopting the above technical solution, a combination of 1-10% polyurethane and 1-10% polyurethane acrylate fatliquor is used to improve the fullness, firmness, and softness of the leather produced. If the polyurethane acrylate fatliquor content is too low, the fullness and firmness of the leather decrease, the bonding strength between the film layer on the leather surface and the leather embryo decreases, and the wear resistance and yellowing resistance decrease. If the polyurethane content is too low, the softness of the leather decreases, the bonding strength between the protective film on the leather embryo surface and the leather embryo decreases, and the wear resistance and oxidation resistance decrease.

[0026] Preferably, the greasing process for furniture leather further comprises an acid-adding and color-fixing step after the dyeing / greasing step and before the water-washing and drum-drying step. The treatment process of the acid-adding and color-fixing step is as follows: placing the fourth preform in a mixture of 100-200% water and 0.5-4% formic acid, treating it for 5-30 minutes at a temperature of 30-60°C and a rotation speed of 2-12 r / min; then adding 1-20% carboxyl silicone oil and treating it for 5-45 minutes; then adding 1-20% non-ionic silicone oil and treating it for 5-45 minutes, and draining the liquid.

[0027] By adopting the above technical solution, formic acid can help the dye penetrate into the leather and enhance the dyeing effect.

[0028] Carboxyl silicone oil and non-ionic silicone oil have a high bonding force with the protein fibers of leather, which reduces the atomization value of leather, reduces the friction between protein fibers, enhances the plump, round and soft feel of leather, and has a good filling effect.

[0029] Preferably, the molecular particle size of the carboxyl silicone oil is 150-300 nm; the molecular particle size of the nonionic silicone oil is 50-150 nm.

[0030] By adopting the above technical solution, carboxyl silicone oil with larger molecules can act on the inside and surface of protein fibers, and non-ionic silicone oil with smaller molecular weight can durably wrap the protein fibers, giving the leather an oily feel and a deeper and brighter mercerizing effect. The carboxyl silicone oil with larger molecules is used in combination with the non-ionic silicone oil with smaller molecular weight, which better protects the protein fibers of the leather, so that the prepared leather has better fullness and firmness while maintaining good softness; it better fills the small holes and defects on the leather surface, reduces the volatilization of small molecular substances in the leather embryo, and reduces the VOC value and atomization value. Part of the carboxyl silicone oil adheres to the surface of the leather, improves the density of the film layer formed on the leather surface, improves the color fastness and wash fastness, thereby achieving a color fixing effect, reduces the contact of the leather with oxygen, and improves the oxidation resistance and yellowing resistance.

[0031] Preferably, after the fourth preform is treated with non-ionic silicone oil, a color fixing composition is added and the treatment is continued for 5-30 minutes, wherein the color fixing composition comprises 0.2-1.5% formic acid and 0.2-5% chromium powder.

[0032] By adopting the above technical solution, formic acid promotes the penetration of chromium powder into the leather embryo, further improving the firmness of the leather and the bonding strength between the chromium powder and the leather; the carboxyl silicone oil with larger molecules and the non-ionic silicone oil with smaller molecular weight penetrate into the interior of the leather embryo, allowing more chromium powder to combine with the surface of the leather embryo, thereby improving the density of the film layer on the surface of the leather embryo, thereby reducing the VOC value and atomization value of the prepared leather, reducing the contact of the leather with oxygen, and improving the oxidation resistance and yellowing resistance.

[0033] Preferably, the color fixing composition further comprises 0.2-1% nano organic bentonite.

[0034] By adopting the above technical solution, nano-organic bentonite can not only promote the dispersion of chromium powder, but also enhance the bonding strength between the film layer on the leather surface and the leather embryo and the density of the film layer; the adsorption performance of nano-organic bentonite can adsorb some small molecules, slowly release and reduce the release of small molecule volatile substances; thereby reducing the VOC value and atomization value of the prepared leather, reducing the contact of leather with oxygen, and improving oxidation resistance and yellowing resistance.

[0035] In summary, this application has the following beneficial effects:

[0036] 1. The present application provides a greasing process for furniture leather, which comprises the following processes in sequence: rinsing → chrome retanning → water washing and neutralization → dyeing / greasing → water washing and drum drying; on the one hand, a relatively stable greasing agent is used in the preparation process of the present application, which reduces the volatilization and oxidation of the greasing agent during the use of the leather, thereby reducing the VOC value and atomization value released by the leather, and improving the oxidation resistance of the leather; on the other hand, the acrylate retanning agent, dicyandiamide and melamine in the dyeing / greasing step form a protective film with good bonding with the leather embryo on the surface of the leather embryo, filling the small holes and defects on the surface of the leather, reducing the contact of the leather with oxygen, further reducing the VOC value and atomization value of the prepared leather, and improving the light resistance and oxidation resistance.

[0037] 2. In the dyeing / fatting step, the combination of acrylate retanning agent, disperse tannin and white tannin improves the fullness and firmness of the leather, reduces the VOC value and atomization value of the leather, reduces the leather's contact with oxygen, and thus improves its oxidation resistance. At the same time, disperse tannin, white tannin, acrylate retanning agent are used in combination with dicyandiamide and melamine to improve the uniformity of the protective film formed and its bonding strength with the leather embryo, thereby improving the leather's oxidation resistance and color fastness to friction.

[0038] 3. In the acid-adding and color-fixing step, the combination of macromolecular carboxyl silicone oil, non-ionic silicone oil, chromium powder and nano-organic bentonite is used to further improve the firmness of the leather and the density of the surface film layer of the leather embryo, further reduce the VOC value and atomization value of the prepared leather, reduce the contact of leather with oxygen, and improve the oxidation resistance and yellowing resistance. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 This is a detection graph of the atomization value of Example 1 in this application.

[0040] Figure 2 This is the detection spectrum of VOC in Example 1 of this application.

[0041] Figure 3 This is a detection graph of the atomization value of Example 2 in this application.

[0042] Figure 4 This is the detection spectrum of VOC in Example 2 of this application.

[0043] Figure 5 It is the detection spectrum of the atomization value of the control sample in this application.

[0044] Figure 6 It is the detection spectrum of VOC of the control sample in this application.

[0045] Figure 7 It is a detection chart of the atomization value of conventional leather generally available on the market.

[0046] Figure 8 This is the VOC detection spectrum of conventional leather generally available on the market.

[0047] Figure 9 It is a detection chart of the atomization value of conventional leather embryos generally available on the market.

[0048] Figure 10 This is the VOC detection spectrum of conventional leather embryos generally available on the market. DETAILED DESCRIPTION

[0049] raw material

[0050] Non-ionic silicone oil (Silicone Oil 7232B, Guangdong Honghao Chemical Co., Ltd.), protein filler (Model: FILLER 532, pH: 4-6, Supplier: Jiaxing Honglin Leather Chemical Co., Ltd.), neutralized tannin (white powder, active ingredient: ≥98%, pH 6-7), white tannin (methylene-bonded phenolsulfonic acid condensate, pH (1:9) approximately 4, active ingredient ≥95%), tannin extract (powder, industrial grade, active ingredient 70%, pH: 4.3-4.8), Dye (Acid Blue 9, active ingredient 99%), acrylic polymer retanning agent (name: Acrylic Retanning Agent XF, main components: copolymer of acrylic acid and ethylene monomers, supplier: Yingshan County Changtai Chemical Co., Ltd.), dispersed tannin (active ingredient 98%, aromatic condensed tannin), polyurethane acrylate fatliquor (viscosity: 1500S), castor oil (water solubility <0.1g / 100mL, viscosity 25mPa·s), nano organic bentonite (specific gravity g / cm 3 31.85, XRDd0011.3nm).

[0051] Example

[0052] Example 1, a fatliquoring process for furniture leather, using raw materials in the amounts shown in Table 1, comprises the following steps in sequence: rinsing → chrome retanning → drum tanning overnight → water washing and neutralization → dyeing / fatting → acid addition and color fixation → water washing, drum drying.

[0053] The weight percentages of the following raw materials are based on the mass of the embryo skin.

[0054] Rinsing: Weigh the embryonic skin (use grease-free embryonic skin) and add it to a rotating drum, add rinsing liquid (1.5% fatty alcohol polyoxyethylene ether AEO-9, 0.3% ethoxylated fatty alcohol MOA-7, 1% oxalic acid and 300% water at 45°C), and treat it at a temperature of 45°C and a speed of 8r / min for 30 minutes; then add 0.3% formic acid and treat it for 10 minutes, then drain the liquid to prepare the first preform.

[0055] Chrome retanning: adding a chrome retanning treatment solution (1% chrome powder, 4% protein filler, 0.2% polyurethane fatliquor and 200% water) into a rotary drum, treating the first preform at a temperature of 40° C. and a rotation speed of 8 r / min for 60 min; then adding 1.5% sodium formate and 0.2% baking soda, and continuing to treat for 5 min; then adding 1.4% baking soda, and performing a second baking soda treatment for 5 min; then adding 0.2% baking soda, and performing a third baking soda treatment for 60 min to prepare a second preform.

[0056] Stop drumming overnight: After the second preform is treated with baking soda for the third time, stop drumming overnight. The next day, treat for 5 minutes at a rotation speed of 8 r / min and drain the liquid.

[0057] Washing and neutralization: add 200% water, 0.5% neutralized tannin, and 1.5% sodium formate to a rotary drum, and treat at 55°C and a rotation speed of 8 r / min for 5 minutes; then add 0.2% baking soda and treat for 30 minutes; then add 0.5% acrylate retanning agent (methyl acrylate with an average particle size of 83 nm) and treat for 5 minutes to prepare a third preform, and then drain.

[0058] Dyeing / fatliquoring: 200% water and 16% acrylic retanning agent (composed of 5% acrylic polymer retanning agent with an average particle size of 376 nm and 5% methyl acrylate with an average particle size of 83 nm) were added to a rotary drum, and the third preform was treated at 55° C. for 5 minutes. Then, a dye retanning agent composition (composed of 8% dicyandiamide, 1% melamine, 5% disperse tannins, 20% tannin extracts, 1% white tannins, and 6% dye) was added and treated for 5 minutes. Then, a fatliquoring composition (10% polyurethane and 1% polyurethane acrylate fatliquoring agent) was added, and the treatment was continued for 80 minutes. The liquid was drained to prepare a fourth preform.

[0059] Acid fixation: add 200% water and 4% formic acid to a rotary drum, pH 3.95±0.05, and treat at 60°C for 30 minutes; then add 20% carboxyl silicone oil with an average molecular particle size of 230nm and treat for 5 minutes; then add 1% non-ionic silicone oil with an average molecular particle size of 100nm and treat for 5 minutes; then add a fixing composition (0.2% formic acid and 0.2% chromium powder), treat for 5 minutes, and drain.

[0060] Washing and drum drying: the fourth preformed product after acid fixation is taken out of the drum, placed on a horse and allowed to stand for 8 hours, squeezed and stretched, dried on a shed, rehumidified and allowed to stand for 8 hours, shaken and softened, and the leather for furniture is prepared.

[0061] Example 2-3, a fatliquoring process for furniture leather, differs from Example 1 in that different raw materials and process parameters are used, as shown in Table 1.

[0062] Table 1. List of raw materials and process parameter settings used in the fatliquoring process for furniture leather in Examples 1-3

[0063]

[0064]

[0065]

[0066]

[0067] Example 4, a fatliquoring process for furniture leather, differs from Example 1 in that, in the acrylic retanning agent in the dyeing / fatliquoring step, an acrylic polymer retanning agent with an average particle size of 376 nm is used in equal amounts to replace methyl acrylate with an average particle size of 83 nm.

[0068] Example 5, a fatliquoring process for furniture leather, differs from Example 1 in that, in the acrylic retanning agent in the dyeing / fatliquoring step, methyl acrylate with an average particle size of 83 nm is used in equal amounts to replace the acrylic polymer retanning agent with an average particle size of 376 nm.

[0069] Example 6, a fatliquoring process for furniture leather, differs from Example 1 in that, in the acrylic retanning agent in the dyeing / fatliquoring step, castor oil is used in equal amounts to replace methyl acrylate with an average particle size of 83 nm.

[0070] Example 7, a fatliquoring process for furniture leather, differs from Example 1 in that formic acid is not used in the rinsing step; and in the chrome retanning step, the second and third baking soda treatments are not performed.

[0071] Example 8, a fatliquoring process for furniture leather, differs from Example 1 in that formic acid is not used in the rinsing step; in the chrome retanning step, the second and third baking soda treatments are not performed; and overnight drumming is not used.

[0072] Example 9, a fatliquoring process for furniture leather, differs from Example 1 in that, in the rinsing step, formic acid and oxalic acid are added simultaneously, and the rinsing step time is set to 40 minutes; in the chrome retanning step, in the second baking soda treatment, 3% baking soda is used for 65 minutes, and no baking soda is used for the third treatment.

[0073] Example 10, a fatliquoring process for furniture leather, differs from Example 1 in that 1.5% formic acid is used in the rinsing step; in the chrome retanning step, no third treatment with baking soda is used; and there is no overnight drum stop.

[0074] Examples 11-15, a fatliquor process for furniture leather, differ from Example 1 in that different amounts of polyurethane and polyurethane acrylate fatliquors are used in the fatliquor composition in the dyeing / fatliquor step, as shown in Table 2.

[0075] Table 2. Dosage setting list of polyurethane and polyurethane acrylate fatliquors used in the dyeing / fatting steps of Examples 11-15 and Example 1

[0076]

[0077] Example 16, a fatliquoring process for furniture leather, differs from Example 1 in that non-ionic silicone oil is not used.

[0078] Example 17, a fatliquoring process for furniture leather, differs from Example 1 in that carboxyl silicone oil is not used.

[0079] Example 18, a fatliquoring process for furniture leather, differs from Example 1 in that non-ionic silicone oil and carboxyl silicone oil are not used.

[0080] Example 19, a fatliquoring process for furniture leather, differs from Example 1 in that the formic acid fixing step is not adopted.

[0081] Example 20, a fatliquoring process for furniture leather, differs from Example 1 in that, in the rinsing step, the formic acid fixation step is not adopted; polyurethane is not used in the fatliquoring composition of the dyeing / fatting step; in the chrome retanning step, the second treatment with baking soda and the third treatment with baking soda are not adopted; the drum is not stopped overnight, and formic acid is not used in the rinsing step.

[0082] Example 21, a fatliquoring process for furniture leather, differs from Example 1 in that, in the acid-adding and color-fixing step, the color-fixing composition further comprises 1% nano-organic bentonite.

[0083] Example 22, a fatliquoring process for furniture leather, differs from Example 1 in that, in the acid-adding and color-fixing step, the color-fixing composition further comprises 0.2% nano-organic bentonite.

[0084] Example 23, a fatliquoring process for furniture leather, differs from Example 18 in that, in the acid-adding and color-fixing step, the color-fixing composition further comprises 1% nano-organic bentonite.

[0085] Comparative Example

[0086] Comparative Example 1 is a fatliquoring process for furniture leather, which differs from Example 20 in that no acrylic retanning agent is used in the dyeing / fatliquoring step; and an equal amount of white tannin is used to replace dispersed tannin.

[0087] Comparative Example 2 is a fatliquoring process for furniture leather, which differs from Example 20 in that, in the dyeing / fatting step, an equal amount of dicyandiamide is used to replace melamine; and an equal amount of white tannin is used to replace dispersed tannin.

[0088] Comparative Example 3, a fatliquoring process for furniture leather, differs from Example 20 in that, in the dyeing / fatting step, melamine is used in an equal amount to replace dicyandiamide; disperse tannin is used in an equal amount to replace white tannin; and in the chrome retanning step, turpentine is used in an equal amount to replace the polyurethane fatliquoring agent.

[0089] Performance testing

[0090] Test 1: Oxidation resistance

[0091] According to method A in HG / T3689-2014, a 300W sunlamp was used to irradiate the test sample at 40°C. After irradiation for 54 hours, a gray scale was used to evaluate the color difference of the test sample before and after irradiation. Level 5 indicates better oxidation resistance and level 1 indicates the worst oxidation resistance.

[0092] The grey scale evaluation is carried out in accordance with GB / T250-2008 / ISO105-A02:1993 “Textiles - Tests for Colour Fastness - Grey Scale for Assessment of Change in Colour”.

[0093] Test 2: Fogging value (FOG value)

[0094] The atomization value of the test sample was tested in accordance with VDA278:2016 using a gas chromatography-mass spectrometer and a thermal desorber / thermal desorber. The test result was taken as the highest value in the spectrum.

[0095] Test 3: VOC value

[0096] The VOC value of the test sample was tested in accordance with VDA278:2016 using a gas chromatography-mass spectrometer and a thermal desorber / thermal desorber. The test result was taken as the highest value in the spectrum.

[0097] Test 4: Color fastness to rubbing

[0098] The test samples were evaluated for color fastness to rubbing in accordance with GB / T39366-2020 "Leather Color Fastness Tests - Color Fastness to Rubbing", with 50 dry rubbing times and 20 wet rubbing times. The test samples before and after rubbing were evaluated and rated according to the grey scale. The grey scale evaluation was carried out in accordance with GB / T 250-2008 / ISO105-A02:1993 "Textiles - Color Fastness Tests - Grey Scale for Assessment of Color Change".

[0099] Test 5: Sensory evaluation

[0100] Five evaluators with at least 1.5 years of experience in leather sensory testing were invited to evaluate the feel, fullness, and softness of the test samples. Each evaluator evaluated two different locations on each sample, generating two values. The final score for fullness and softness of each sample was the average of the 10 scores generated by the evaluators. The rating scale is: Excellent (5 points); Good (4 points); Fair (3 points); Fair (2 points); and Poor (1 point).

[0101] Test samples: The furniture leathers prepared in Examples 1-23 were used as example samples; the furniture leathers prepared in Comparative Examples 1-3 were used as comparative example samples; and the grease-free leather blanks that had not been treated with the furniture leather greasing process were used as control samples.

[0102] Test results: The test results of oxidation resistance, fogging value, VOC value, color fastness to friction and sensory evaluation of the furniture leather prepared in Examples 1-23, Comparative Examples 1-3 and the control sample are shown in Table 3.

[0103] Table 3. Test results of oxidation resistance, fogging value, VOC value, color fastness to rubbing and sensory evaluation of furniture leather prepared by Examples 1-23, Comparative Examples 1-3 and control samples

[0104]

[0105]

[0106] Combining Examples 1-23 and Comparative Examples 1-3 and Table 3, it can be seen that:

[0107] The furniture leathers prepared in Examples 1-23 exhibited superior oxidation resistance, color fastness to friction, fullness, softness, fogging value, and VOC value to those of Comparative Examples 1-3, the control sample, and conventional leathers available on the market. This may be due to the following: Firstly, the use of a relatively stable fatliquor in the preparation process of the present application reduces volatilization and oxidation of the fatliquor during use, thereby reducing the VOC value and fogging value released by the leather and improving the oxidation resistance of the leather; secondly, the acrylate retanning agent, dicyandiamide, and melamine in the dyeing / fatting step form a protective film with good adhesion to the leather embryo, filling small holes and defects on the leather surface and reducing the leather's exposure to oxygen. This further reduces the VOC value and fogging value of the prepared leather and improves its light and oxidation resistance.

[0108] The results of Example 1 and Examples 4-6 show that the acrylic retanning agent composed of an acrylic ester with a smaller average molecular particle size and an acrylic polymer retanning agent with a larger average molecular particle size has a better compatibility effect, can improve the oxidation resistance, friction color fastness, fullness and softness of the prepared leather, and reduce the fogging value and VOC value.

[0109] The reasons may be that: on the one hand, small molecule acrylates can penetrate into the smaller gaps inside the leather embryo protein fibers, thereby improving the tanning effect and enhancing the bonding strength between the protective film formed by acrylate retanning agents, dicyandiamide and melamine on the surface of the leather embryo and the leather embryo, thereby improving the color fastness to friction and fullness of the prepared leather; on the other hand, the combination of the two can better fill the small holes and defects on the surface and inside of the leather, and the acrylate retanning agent has a high compatibility with the acrylic polymer retanning agent, which further reduces the volatilization and migration of small molecular substances in the leather embryo, reduces the VOC value and atomization value, reduces the contact of leather with oxygen, and improves the smoothness, strength, oxidation resistance and color fastness to friction of the leather.

[0110] The color fastness to friction, fullness and softness of the furniture leather prepared in Example 1 are better than those of Examples 7-10. The possible reasons are that formic acid is added separately in the rinsing step, and the formic acid added last can better open the pores of the leather and enhance the penetration-promoting effect. In addition, the appropriate amount of formic acid is set to reduce the VOC value and the atomization value. In the chrome retanning step, baking soda is added in batches and then the drum is stopped overnight, which promotes better combination of chrome with the leather embryo and enhances the tanning effect, thereby improving the color fastness to friction, fullness and softness of the prepared furniture leather.

[0111] The results of Examples 1 and 11-15 demonstrate that the combination of polyurethane and polyurethane acrylate fatliquors in the fatliquor composition during the dyeing / fatting step, with 3-8% polyurethane and 3-8% polyurethane acrylate fatliquors, produces leather with excellent oxidation resistance, color fastness to rubbing, fullness, and softness. This may be due to the fact that the combination of the soft fatliquor polyurethane and the firming polymer fatliquor polyurethane acrylate not only accelerates the penetration and fixation of chromium, improving retanning efficiency and enhancing the filling and fullness of the leather, but also increases the density of the protective film formed on the surface of the leather, imparting a waxy grain to the leather, improving oxidation resistance and color fastness to rubbing, and reducing fogging and VOC values.

[0112] The atomization value and VOC value of the furniture leather prepared by Example 1 are lower than those of Examples 16-18, and the oxidation resistance, color fastness to rubbing, fullness and softness are better than those of Examples 16-18. The test results show that the use of non-ionic silicone oil and carboxyl silicone oil in combination in the acid-adding and color-fixing step reduces the atomization value and VOC value of the prepared furniture leather, and improves the oxidation resistance, color fastness to rubbing, fullness and softness.

[0113] The reason may be that the carboxyl silicone oil with larger molecules can act on the inside and surface of protein fibers, and the non-ionic silicone oil with smaller molecular weight can durably wrap the protein fibers, giving the leather an oily feel and a deeper and brighter mercerizing effect. The carboxyl silicone oil with larger molecules is used in combination with the non-ionic silicone oil with small molecular weight, which better protects the protein fibers of the leather, so that the prepared leather has better fullness and firmness, while maintaining good softness; the carboxyl silicone oil with larger molecules is used in combination with the non-ionic silicone oil with small molecular weight, which better fills the small holes and defects on the surface of the leather, reduces the volatilization of small molecular substances in the leather embryo, and reduces the VOC value and atomization value. Part of the carboxyl silicone oil adheres to the surface of the leather, improves the density of the film layer formed on the surface of the leather, improves the color fastness and wash fastness, thereby achieving a color fixing effect, reduces the contact of leather with oxygen, and improves oxidation resistance and yellowing resistance.

[0114] The test results of Examples 1, 8, and 19-20 show that by optimizing the fatliquoring process for furniture leather, the formic acid fixation step, the rinsing step, the chrome retanning step, and the dyeing / fatting step are synergistically coordinated with each other, thereby further reducing the atomization value and VOC value of the prepared furniture leather, and improving the oxidation resistance, color fastness to friction, fullness, and softness.

[0115] The atomization value and VOC value of the furniture leather prepared in Example 21 are lower than those in Example 1, and the color fastness to rubbing and softness are better than those in Example 1; the atomization value and VOC value of the furniture leather prepared in Example 22 are lower than those in Example 2, and the color fastness to rubbing and softness are better than those in Example 2; this indicates that in the acid-adding and color-fixing step, the use of 0.2-1% nano-organic bentonite in the color-fixing composition reduces the atomization value and VOC value of the prepared leather, and improves the color fastness to rubbing and softness.

[0116] The reason may be that: nano-organic bentonite can not only promote the dispersion of chromium powder, but also enhance the bonding strength and density of the film layer between the leather surface and the leather embryo; the adsorption performance of nano-organic bentonite can adsorb some small molecules, slowly release and reduce the release of small molecule volatile substances; thereby reducing the VOC value and atomization value of the prepared leather, reducing the contact of leather with oxygen, and improving oxidation resistance.

[0117] It can be seen from the test results of Examples 21 and 23 that in the acid-adding and color-fixing step of Example 1, the color-fixing composition adopts nano-organic bentonite, and the degree of reduction in the atomization value and VOC value of the prepared leather is higher than that in Example 18, indicating that the nano-organic bentonite has a good synergistic effect with the non-ionic silicone oil and carboxyl silicone oil in the formic acid color-fixing step, which may be because the non-ionic silicone oil and carboxyl silicone oil can promote the dispersion of nano-organic bentonite and improve the uniformity of the film layer on the surface of the leather embryo.

[0118] This specific embodiment is merely an explanation of the present application and is not a limitation of the present application. After reading this specification, those skilled in the art may make non-creative modifications to the present embodiment as needed, but as long as they are within the scope of the claims of the present application, they are protected by the patent law.

Claims

1. A greasing process for furniture leather, characterized in that: The following steps are included in sequence: Rinsing: The embryo skin is treated with a rinsing liquid at a temperature of 45-60°C and a rotation speed of 2-12 r / min for 10-30 minutes to prepare a first preform, and then the liquid is drained; the rinsing liquid is composed of 0.3-1.5% fatty alcohol polyoxyethylene ether, 0.3-1.5% ethoxylated fatty alcohol, 0.2-1% oxalic acid and 300-500% water based on the mass of the embryo skin; Chrome retanning: Based on the mass of the leather, the first preform is treated with a chrome retanning solution at a temperature of 40-60°C and a rotation speed of 2-12 r / min for 10-60 minutes; then 0.2-1.5% sodium formate and 0.2-1.5% baking soda are added and the treatment is continued for 5-30 minutes to prepare a second preform; the chrome retanning solution is composed of 1-10% chrome powder, 0.5-4% protein filler, 0.2-2% polyurethane fatliquor and 200-300% water; Washing and neutralization: Based on the mass of the embryonic skin, place the second preformed product in a mixture of 200-400% water, 0.5-2.5% neutralized tannin, and 0.2-1.5% sodium formate, at 35-55°C and a rotation speed of 2-12 r / min for 5-20 minutes; Then, 0.2-1.8% of baking soda is added and the mixture is treated for 5-30 minutes; then 0.5-2.5% of acrylate retanning agent is added and the mixture is treated for 5-40 minutes to prepare a third preform, and the liquid is then drained; Dyeing / fatliquoring: Based on the mass of the leather, place the third preform in a mixture of 2-16% acrylic retanning agent and 100-200% water, and treat at a temperature of 35-55°C and a rotation speed of 2-12 rpm for 5-30 minutes, then add the dye retanning agent composition and continue treating for 5-20 minutes; Then, a fatliquor composition is added and treated for 10-80 minutes to prepare a fourth preform, and then the preform is drained; the dye retanning agent composition comprises 1-8% dicyandiamide, 1-8% melamine, 1-8% disperse tannin, 2-20% tannin extract, 1-8% white tannin and 1-6% dye; the fatliquor composition comprises 1-10% polyurethane acrylate fatliquor; Acid fixation: Based on the mass of the leather embryo, place the fourth preform in a mixture of 100-200% water and 0.5-4% formic acid at a temperature of 30-60°C and a rotation speed of 2-12 r / min for 5-30 minutes; then add 1-20% carboxyl silicone oil and treat for 5-45 minutes; then add 1-20% non-ionic silicone oil and treat for 5-45 minutes, and drain; wherein the average molecular particle size of the carboxyl silicone oil is 150-300nm; the average molecular particle size of the non-ionic silicone oil is 50-150nm; Washing, drum-drying: The fourth preformed product after acid fixation is washed, drained, drum-dryed, and dried to prepare furniture leather.

2. The greasing process for furniture leather according to claim 1, characterized in that: In the rinsing step, after the rinsing liquid is treated, 0.3-1.2% of formic acid is added and then treated for 10-90 minutes.

3. The greasing process for furniture leather according to claim 1, characterized in that: In the chrome retanning step, after adding sodium formate and baking soda, 0.2-1.4% of baking soda is continued to be added for a second baking soda treatment for 5-30 minutes; then 0.2-1.3% of baking soda is added for a third baking soda treatment for 10-60 minutes.

4. A fatliquoring process for furniture leather according to claim 3, characterized in that: In the chrome retanning step, after the third treatment with baking soda, the drum is stopped overnight, and the next day, the drum is treated at a rotation speed of 2-12 r / min for 5-10 minutes and the liquid is drained.

5. The greasing process for furniture leather according to claim 1, characterized in that: In the dyeing / fatliquoring step, the acrylic retanning agent consists of 1-8% of acrylic ester with an average molecular particle size of 50-100 nm and 1-8% of acrylic polymer retanning agent with an average molecular particle size of 100-400 nm.

6. The greasing process for furniture leather according to claim 1, characterized in that: In the dyeing / fatliquoring step, the fatliquoring composition further comprises 1-10% polyurethane.

7. The greasing process for furniture leather according to claim 1, characterized in that: After the fourth preform is treated with non-ionic silicone oil, a color fixing composition is added and the treatment is continued for 5-30 minutes. The color fixing composition includes 0.2-1.5% formic acid and 0.2-5% chromium powder.

8. The greasing process for furniture leather according to claim 7, characterized in that: The color fixing composition further comprises 0.2-1% nano organic bentonite.

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